Drive control method, drive control device, belt apparatus, image forming apparatus, image reading apparatus, computer product

• US 20050099153A1
• Filed: 09/10/2004
• Published: 05/12/2005
• Est. Priority Date: 09/10/2003
• Status: Active Grant

• Current Assignee: Ricoh Company Limited
• Original Assignee: Ricoh Company Limited
• Inventors: Komatsu, Makoto, Andoh, Toshiyuki, Sakai, Yoshihiro
• Granted Patent: US 7,576,509 B2
• Time in Patent Office: Days
• US Class Current: 318/807
• CPC Class Codes: H02P 6/15 Controlling commutation time

Abstract

Driving of a pulse motor is controlled in such a manner that a rotating body driven by the pulse motor rotates at a uniform angular velocity. Angular displacement of the rotating body is detected, a difference between a detection value of the angular displacement and a target value of angular displacement set in advance is calculated, and a drive pulse frequency of a drive pulse signal to be used for driving the pulse motor is calculated based on the difference and a reference drive pulse frequency. Whether the difference is added to the reference drive pulse can be selected.

Claims

1. A drive control method for controlling driving of a pulse motor such that a rotating body driven by the pulse motor rotates at uniform angular velocity, comprising:

detecting angular displacement of the rotating body;

calculating a difference between a detection value of the angular displacement and a target value of angular displacement set in advance; and

calculating a drive pulse frequency of a drive pulse signal to be used for driving for the pulse motor based on the difference and a reference drive pulse frequency to make it possible to select whether the difference is added to the reference drive pulse.

2. The drive control method according to claim 1, wherein, when there is abnormality in a result of the detection of angular displacement of the rotating body, the difference between a detected value of the angular displacement and a target value of angular displacement set in advance is not added to the reference drive pulse.

3. A drive control method for controlling driving of a pulse motor such that a moving body driven by the pulse motor moves at a uniform velocity, comprising:

detecting displacement of the moving body;

calculating a difference between a detection value of the displacement and a target value of displacement set in advance;

calculating a drive pulse frequency of a drive pulse signal to be used for driving for the pulse motor based on the difference and a reference drive pulse frequency, and

selecting whether the difference is added to the reference drive pulse.

4. The drive control method according to claim 3, wherein, when there is abnormality in a result of the detection of displacement of the moving body, the difference between a detected value of the displacement and a target value of displacement set in advance is not added to the reference drive pulse.

5. A drive control device that control driving of a pulse motor such that a rotating body driven by the pulse motor rotates at uniform angular velocity, comprising:

an angular displacement detecting unit that detects angular displacement of the rotating body;

a difference calculating unit that calculates a difference between a detection value of the angular displacement and a target value of angular displacement set in advance; and

a drive pulse frequency calculating unit that calculates a drive pulse frequency of a drive pulse signal to be used for driving for the pulse motor based on the difference and a reference drive pulse frequency to make it possible to select whether the difference is added to the reference drive pulse.

6. The drive control device according to claim 5, wherein, when there is abnormality in a result of the detection of angular displacement of the rotating body, the unit, which makes it possible to select whether the difference is added to the reference drive pulse, does not add the difference between a detection value of the angular displacement and a target value of angular displacement set in advance.

7. The drive control method according to claim 5, wherein,

the rotating body is a drive rotating body having a belt laid over between the drive rotating body and a driven rotating body, and

driving for the pulse motor is controlled such that the drive rotating body rotates at uniform angular velocity.

8. The drive control method according to claim 5, wherein

the rotating body is a driven rotating body having a belt laid over between the driven rotating body and a drive rotating body, and

driving for the pulse motor is controlled such that the driven rotating body rotates at uniform angular velocity.

9. The drive control method according to claim 5, wherein an integrating element is not present in the drive pulse frequency calculating unit.

10. A drive control device that controls driving of a pulse motor such that a moving body driven by the pulse motor moves at a uniform velocity, comprising:

a difference calculating unit that calculates a difference between a detection value of displacement of the moving body and a target value of displacement set in advance;

a drive pulse frequency calculating unit that calculates a drive pulse frequency of a drive pulse signal to be used for driving for the pulse motor based on the difference and a reference drive pulse frequency; and

a selecting unit that makes it possible to select whether the difference is added to the reference drive pulse.

11. The drive control device according to claim 10, wherein, when there is abnormality in a result of the detection of displacement of the moving body, the selecting unit selects that the difference between a detected value of the displacement and a target value of displacement set in advance is not added to the reference drive pulse.

12. The drive control device according to claim 10, wherein

the moving body is a belt laid over between a drive rotating body and a driven rotating body, and

driving of the pulse motor is controlled such that the belt moves at a uniform velocity.

13. The drive control device according to claim 12, further comprising

a displacement detection device that detects displacement of the moving body, the displacement detection device is a surface sensor has a joint for one round of a belt, and the surface sensor attached to a surface of the belt, wherein

abnormality in detection of displacement of the moving body is the joint.

14. A belt apparatus comprising:

a belt that is laid over plural support rotating bodies;

a drive control device that controls driving of the belt; and

a drive device that drives the belt based on a drive pulse frequency output from the drive control device, the drive control device includes

an angular displacement detecting unit that detects angular displacement of the rotating body;

a difference calculating unit that calculates a difference between a detection value of the angular displacement and a target value of angular displacement set in advance; and

a drive pulse frequency calculating unit that calculates a drive pulse frequency of a drive pulse signal to be used for driving for the pulse motor based on the difference and a reference drive pulse frequency to make it possible to select whether the difference is added to the reference drive pulse.

15. A belt apparatus comprising:

a belt that is laid over plural support rotating bodies;

a drive control device that controls driving of the belt; and

a drive device that drives the belt based on a drive pulse frequency output from the drive control device, the drive control device includes

a difference calculating unit that calculates a difference between a detection value of displacement of the moving body and a target value of displacement set in advance;

a drive pulse frequency calculating unit that calculates a drive pulse frequency of a drive pulse signal to be used for driving for the pulse motor based on the difference and a reference drive pulse frequency; and

a selecting unit that makes it possible to select whether the difference is added to the reference drive pulse.

16. An image forming apparatus comprising:

an image bearing member;

a drive control device that controls driving of the image bearing member; and

a drive device that drives the image bearing member based on a drive pulse frequency output from the drive control device, wherein the drive control device includes

an angular displacement detecting unit that detects angular displacement of the rotating body;

a difference calculating unit that calculates a difference between a detection value of the angular displacement and a target value of angular displacement set in advance; and

a drive pulse frequency calculating unit that calculates a drive pulse frequency of a drive pulse signal to be used for driving for the pulse motor based on the difference and a reference drive pulse frequency to make it possible to select whether the difference is added to the reference drive pulse.

17. The image forming apparatus according to claim 16, wherein the mage bearing member is a photosensitive drum.

18. The image forming apparatus according to claim 16, wherein the image bearing member is a photosensitive belt.

19. The image forming apparatus according to claim 17, wherein the image bearing member is a transfer drum.

20. The image forming apparatus according to claim 16, wherein the image bearing member is an intermediate transfer belt.

21. An image forming apparatus comprising:

an image bearing member;

a drive control device that controls driving of the image bearing member; and

a drive device that drives the image bearing member based on a drive pulse frequency output from the drive control device, wherein the drive control device includes

a difference calculating unit that calculates a difference between a detection value of displacement of the moving body and a target value of displacement set in advance;

a drive pulse frequency calculating unit that calculates a drive pulse frequency of a drive pulse signal to be used for driving for the pulse motor based on the difference and a reference drive pulse frequency; and

a selecting unit that makes it possible to select whether the difference is added to the reference drive pulse.

22. The image forming apparatus according to claim 21, wherein the mage bearing member is a photosensitive drum.

23. The image forming apparatus according to claim 21, wherein the image bearing member is a photosensitive belt.

24. The image forming apparatus according to claim 22, wherein the image bearing member is a transfer drum.

25. The image forming apparatus according to claim 21, wherein the image bearing member is an intermediate transfer belt.

26. An image forming apparatus comprising:

a plurality of image bearing members;

a drive control device that control driving for the image bearing members; and

a drive device that drives the image bearing members based on a drive pulse frequency output from the drive control device, wherein the drive control device includes

an angular displacement detecting unit that detects angular displacement of the rotating body;

a difference calculating unit that calculates a difference between a detection value of the angular displacement and a target value of angular displacement set in advance; and

a drive pulse frequency calculating unit that calculates a drive pulse frequency of a drive pulse signal to be used for driving for the pulse motor based on the difference and a reference drive pulse frequency to make it possible to select whether the difference is added to the reference drive pulse.

27. An image forming apparatus comprising:

a plurality of image bearing members;

a drive control device that controls driving of the image bearing members; and

a drive device that drives the image bearing members based on a drive pulse frequency output from the drive control device, wherein the drive control device includes

a difference calculating unit that calculates a difference between a detection value of displacement of the moving body and a target value of displacement set in advance;

a drive pulse frequency calculating unit that calculates a drive pulse frequency of a drive pulse signal to be used for driving for the pulse motor based on the difference and a reference drive pulse frequency; and

a selecting unit that makes it possible to select whether the difference is added to the reference drive pulse.

28. An image reading apparatus comprising:

a moving body that includes an optical system for image reading;

a drive control device that controls driving for the moving body; and

a drive device that drives the moving body based on a drive pulse frequency output from the drive control device, wherein

the image reading apparatus moves the moving body along a surface of an image reading object to read an image, wherein the drive control device includes

an angular displacement detecting unit that detects angular displacement of the rotating body;

a difference calculating unit that calculates a difference between a detection value of the angular displacement and a target value of angular displacement set in advance; and

a drive pulse frequency calculating unit that calculates a drive pulse frequency of a drive pulse signal to be used for driving for the pulse motor based on the difference and a reference drive pulse frequency to make it possible to select whether the difference is added to the reference drive pulse.

29. An image reading apparatus comprising:

a moving body that includes an optical system for image reading;

a drive control device that controls driving for the moving body; and

a drive device that drives the moving body based on a drive pulse frequency output from the drive control device, wherein

the image reading apparatus moves the moving body along a surface of an image reading object to read an image, wherein the drive control device includes

a difference calculating unit that calculates a difference between a detection value of displacement of the moving body and a target value of displacement set in advance;

a drive pulse frequency calculating unit that calculates a drive pulse frequency of a drive pulse signal to be used for driving for the pulse motor based on the difference and a reference drive pulse frequency; and

a selecting unit that makes it possible to select whether the difference is added to the reference drive pulse.

30. A computer program for realizing on a computer drive control of a pulse motor such that a rotating body driven by the pulse motor rotates at a uniform angular velocity, wherein

the computer program causes the computer to realize a function for calculating a difference between a detection value of angular displacement of the rotating body and a target value of angular displacement set in advance, a function for calculating a drive pulse frequency of a drive pulse signal used for driving for the pulse motor based on the difference and a reference drive pulse frequency, and a function for making it possible to select whether the difference is added to the reference drive pulse.

31. A computer program for realizing on a computer drive control of a pulse motor such that a moving body driven by the pulse motor rotates at a uniform velocity, wherein

the computer program causes the computer to realize a function for calculating a difference between a detection value of displacement of the moving body and a target value of displacement set in advance, a function for calculating a drive pulse frequency of a drive pulse signal used for driving for the pulse motor based on the difference and a reference drive pulse frequency, and a function for making it possible to select whether the difference is added to the reference drive pulse.

32. A recording medium having stored therein a computer program for drive control for drive control for realizing drive control, which controls driving of a pulse motor such that a rotating body driven by the pulse motor rotates at a uniform angular velocity, using a computer, wherein

the computer program causes the computer to realize a function for calculating a difference between a detection value of angular displacement of the rotating body and a target value of angular displacement set in advance, a function for calculating a drive pulse frequency of a drive pulse signal used for driving for the pulse motor based on the difference and a reference drive pulse frequency, and a function for making it possible to select whether the difference is added to the reference drive pulse.

33. A recording medium having stored therein a computer program for drive control for realizing drive control, which controls driving of a pulse motor such that a moving body driven by the pulse motor rotates at a uniform velocity, using a computer, wherein

the computer program causes the computer to realize a function for calculating a difference between a detection value of displacement of the moving body and a target value of displacement set in advance, a function for calculating a drive pulse frequency of a drive pulse signal used for driving for the pulse motor based on the difference and a reference drive pulse frequency, and a function for making it possible to select whether the difference is added to the reference drive pulse.

34. A position control method for feedback-controlling displacement in a rotating direction of a rotating body, which is driven to rotate by a drive source, by reading a signal generated according to rotation of the rotating body, wherein

when a signal amount read in sampling time is outside a range compared with a defined signal amount, correction processing for a feedback signal is performed.

35. The position control method according to claim 34, wherein the defined signal amount is set taking into account a variation width that could occur due to usual disturbance.

36. The position control method according to claim 34, wherein, as the correction processing, the defined signal amount is used instead of the signal amount read in sampling time.

37. The position control method according to claim 34, wherein, as the correction processing, a signal amount measured before present sampling time is used instead of the signal amount read in sampling time.

38. The position control method according to claim 34, wherein, as the correction processing, an average value of signal amounts measured before present sampling time is used instead of the signal amount read in sampling time.

39. The position control method according to claim 34, wherein, as the correction processing, a signal amount, which is measured in a time section before present sampling time and calculated from velocity of the rotating body, is used instead of the signal amount read in sampling time.

40. The position control method according to claim 34, wherein a value of deviation between a reference signal and a feedback signal in the feedback control is set to zero while the correction processing is performed.

41. A position control method for feedback-controlling displacement in a rotating direction of a rotating body, which is driven to rotate by a drive source, by reading a scale pulse generated based on a scale provided in the rotating body, wherein

when a scale pulse number read in sampling time is outside a range compared with a defined scale pulse number, correction processing for a feedback signal is performed.

42. The position control method according to claim 41, wherein the defined scale pulse number is set taking into account a variation width that could occur due to usual disturbance.

43. The position control method according to claim 41, wherein at least one discontinuous part is present in the scale.

44. The position control method according to claim 41, wherein, as the correction processing, the defined scale pulse number is used instead of the scale pulse number read in sampling time.

45. The position control method according to claim 41, wherein, as the correction processing, a scale pulse number measured before present sampling time is used instead of the scale pulse number read in sampling time.

46. The position control method according to claim 41, wherein, as the correction processing, an average value of scale pulse numbers measured before present sampling time is used instead of the scale pulse number read in sampling time.

47. The position control method according to claim 41, wherein, as the correction processing, a scale pulse number, which is measured in a time section before present sampling time and calculated from velocity of the rotating body, is used instead of the scale pulse number read in sampling time.

48. A position control device that controls position of a rotating body, comprising:

a signal generating unit that is provided in a rotating body driven to rotate by a drive source, which operates in response to a control signal, and generates a signal for detecting displacement in a rotating direction of the rotating body; and

a control unit that reads the signal generated by the signal generating unit, feedbacks the signal, calculates a deviation between present displacement and a target displacement, and outputs the control signal anew, wherein

when a signal amount read in sampling time is outside a range compared with a defined signal amount, the control unit performs correction processing for a feedback signal.

49. The position control device according to claim 48, wherein the defined signal amount is set taking into account a variation width that could occur due to usual disturbance.

50. The position control device according to claim 48, wherein, as the correction processing, the control unit uses the defined signal amount instead of the signal amount read in sampling time.

51. The position control device according to claim 48, wherein, as the correction processing, the control unit uses a signal amount measured before present sampling time instead of the signal amount read in sampling time.

52. The position control device according to claim 48, wherein, as the correction processing, the control unit uses an average value of signal amounts measured before present sampling time instead of the signal amount read in sampling time.

53. The position control device according to claim 48, wherein, as the correction processing, the control unit uses a signal amount, which is measured in a time section before present sampling time and calculated from velocity of the rotating body, instead of the signal amount read in sampling time.

54. The position control device according to claim 48, wherein the control unit sets a value of the deviation to zero while the control unit performs the correction processing.

55. A position control device that controls position of a rotating body, comprising:

a scale that is provided in a rotating body driven to rotate by a drive source, which operates in response to a control signal;

a scale pulse generating unit that generates a pulse for detecting displacement in a rotating direction of the rotating body based on the scale; and

a control unit that reads a scale pulse generated by the scale pulse generating unit, feedbacks the scale pulse, calculates a deviation between present displacement and target displacement, and outputs the control signal anew, wherein

when a scale pulse number read in sampling time is outside a range compared with a defined scale pulse number, the control unit performs correction processing for a feedback signal.

56. The position control device according to claim 55, wherein the defined scale pulse number is set taking into account a variation width that could occur due to usual disturbance.

57. The position control device according to claim 55, wherein at least one discontinuous part is present in the scale.

58. The position control device according to claim 55, wherein, as the correction processing, the control unit uses the defined scale pulse number instead of the scale pulse number read in sampling time.

59. The position control device according to claim 55, wherein, as the correction processing, the control unit uses a scale pulse number measured before present sampling time instead of the scale pulse number read in sampling time.

60. The position control device according to claim 55, wherein, as the correction processing, the control unit uses an average value of scale pulse numbers measured before present sampling time instead of the scale pulse number read in sampling time.

61. The position control device according to claim 55, wherein, as the correction processing, the control unit uses a scale pulse number, which is measured in a time section before present sampling time and calculated from velocity of the rotating body, instead of the scale pulse number read in sampling time.

62. An image forming apparatus comprising:

an image bearing member on which an image is formed; and

a position control device that controls position of a rotating body that drive controls the image bearing member and includes

a signal generating unit that is provided in a rotating body driven to rotate by a drive source, which operates in response to a control signal, and generates a signal for detecting displacement in a rotating direction of the rotating body; and

a control unit that reads the signal generated by the signal generating unit, feedbacks the signal, calculates a deviation between present displacement and a target displacement, and outputs the control signal anew, wherein

when a signal amount read in sampling time is outside a range compared with a defined signal amount, the control unit performs correction processing for a feedback signal.

63. The image forming apparatus according to claim 62, wherein the image bearing member is a photosensitive drum.

64. The image forming apparatus according to claim 62, wherein the image bearing member is a transfer drum.

65. The image forming apparatus according to claim 62, wherein the image bearing member is a photosensitive belt.

66. The image forming apparatus according to claim 62, wherein the image bearing member is an intermediate transfer belt.

67. The image forming apparatus according to claim 62, wherein the image bearing member is a direct transfer belt.

68. The image forming apparatus according to claim 62, further comprising a recording medium that is detachably connected to a control unit actuating the apparatus and in which a computer program for controlling a rotating body is recorded, wherein

position control for the image bearing member is performed by the computer program for a rotating body recorded in the recording medium.

69. The image forming apparatus according to claim 62,

wherein a control unit actuating the apparatus is provided to be connectable to a communication network, and

position control for the image bearing member is performed by the computer program for controlling a rotating body captured from a server on the communication network.

70. An image forming apparatus comprising:

an image bearing member on which an image is formed; and

a position control device that drive controls the image bearing member and includes

a scale that is provided in a rotating body driven to rotate by a drive source, which operates in response to a control signal;

a scale pulse generating unit that generates a pulse for detecting displacement in a rotating direction of the rotating body based on the scale; and

a control unit that reads a scale pulse generated by the scale pulse generating unit, feedbacks the scale pulse, calculates a deviation between present displacement and target displacement, and outputs the control signal anew, wherein

when a scale pulse number read in sampling time is outside a range compared with a defined scale pulse number, the control unit performs correction processing for a feedback signal.

71. The image forming apparatus according to claim 70, wherein the image bearing member is a photosensitive drum.

72. The image forming apparatus according to claim 70, wherein the image bearing member is a transfer drum.

73. The image forming apparatus according to claim 70, wherein the image bearing member is a photosensitive belt.

74. The image forming apparatus according to claim 70, wherein the image bearing member is an intermediate transfer belt.

75. The image forming apparatus according to claim 70, wherein the image bearing member is a direct transfer belt.

76. The image forming apparatus according to claim 70, further comprising a recording medium that is detachably connected to a control unit actuating the apparatus and in which a computer program for controlling a rotating body is recorded, wherein

position control for the image bearing member is performed by the computer program for a rotating body recorded in the recording medium.

77. The image forming apparatus according to claim 70,

wherein a control unit actuating the apparatus is provided to be connectable to a communication network, and

position control for the image bearing member is performed by the computer program for controlling a rotating body captured from a server on the communication network.

78. An image forming apparatus comprising:

a plurality of image bearing members on which a color image is formed; and

a position control device that controls position of a rotating body that drive controls at least one of the image bearing members and includes

a signal generating unit that is provided in a rotating body driven to rotate by a drive source, which operates in response to a control signal, and generates a signal for detecting displacement in a rotating direction of the rotating body; and

a control unit that reads the signal generated by the signal generating unit, feedbacks the signal, calculates a deviation between present displacement and a target displacement, and outputs the control signal anew, wherein

when a signal amount read in sampling time is outside a range compared with a defined signal amount, the control unit performs correction processing for a feedback signal.

79. The image forming apparatus according to claim 78, further comprising a recording medium that is detachably connected to a control unit actuating the apparatus and in which a computer program for controlling a rotating body is recorded, wherein

position control for the image bearing member is performed by the computer program for a rotating body recorded in the recording medium.

80. The image forming apparatus according to claim 78,

wherein a control unit actuating the apparatus is provided to be connectable to a communication network, and

position control for the image bearing member is performed by the computer program for controlling a rotating body captured from a server on the communication network.

81. An image forming apparatus comprising:

a plurality of image bearing members on which a color image is formed; and

a position control device that drive controls at least one of the image bearing members and includes

a scale that is provided in a rotating body driven to rotate by a drive source, which operates in response to a control signal;

a scale pulse generating unit that generates a pulse for detecting displacement in a rotating direction of the rotating body based on the scale; and

a control unit that reads a scale pulse generated by the scale pulse generating unit, feedbacks the scale pulse, calculates a deviation between present displacement and target displacement, and outputs the control signal anew, wherein

when a scale pulse number read in sampling time is outside a range compared with a defined scale pulse number, the control unit performs correction processing for a feedback signal.

82. The image forming apparatus according to claim 81, further comprising a recording medium that is detachably connected to a control unit actuating the apparatus and in which a computer program for controlling a rotating body is recorded, wherein

position control for the image bearing member is performed by the computer program for a rotating body recorded in the recording medium.

83. The image forming apparatus according to claim 81,

wherein a control unit actuating the apparatus is provided to be connectable to a communication network, and

position control for the image bearing member is performed by the computer program for controlling a rotating body captured from a server on the communication network.

84. An image reading apparatus comprising:

a traveling body drive device that reads an image; and

a position control device that controls position of a rotating body that drive controls the traveling body drive device and includes

a signal generating unit that is provided in a rotating body driven to rotate by a drive source, which operates in response to a control signal, and generates a signal for detecting displacement in a rotating direction of the rotating body; and

a control unit that reads the signal generated by the signal generating unit, feedbacks the signal, calculates a deviation between present displacement and a target displacement, and outputs the control signal anew, wherein

when a signal amount read in sampling time is outside a range compared with a defined signal amount, the control unit performs correction processing for a feedback signal.

85. An image reading apparatus comprising:

a traveling body drive device that reads an image; and

a position control device that drive controls the traveling body drive device and includes

a scale that is provided in a rotating body driven to rotate by a drive source, which operates in response to a control signal;

a scale pulse generating unit that generates a pulse for detecting displacement in a rotating direction of the rotating body based on the scale; and

a control unit that reads a scale pulse generated by the scale pulse generating unit, feedbacks the scale pulse, calculates a deviation between present displacement and target displacement, and outputs the control signal anew, wherein

when a scale pulse number read in sampling time is outside a range compared with a defined scale pulse number, the control unit performs correction processing for a feedback signal.

86. A computer readable recording medium with a computer program stored therein that causes a computer to perform a position control method for feedback-controlling displacement in a rotating direction of a rotating body, which is driven to rotate by a drive source, by reading a signal generated according to rotation of the rotating body, wherein

when a signal amount read in sampling time is outside a range compared with a defined signal amount, correction processing for a feedback signal is performed.

87. A computer readable recording medium with a computer program stored therein that causes a computer to perform a position control method for feedback-controlling displacement in a rotating direction of a rotating body, which is driven to rotate by a drive source, by reading a scale pulse generated based on a scale provided in the rotating body, wherein

when a scale pulse number read in sampling time is outside a range compared with a defined scale pulse number, correction processing for a feedback signal is performed.

88. A position control method for controlling displacement in a rotating direction of a rotating body, which is driven to rotate by a drive source, by reading signals generated according to rotation of the rotating body, wherein

the signals are two kinds of signals, namely, a first signal generated by rotation of the rotating body itself and a second signal generated by rotation of a shaft of the rotating body, and these two signals are used as a control signal selectively.

89. The position control method according to claim 88, wherein, when control is performed based on the second signal, in switching the control to control based on the first signal at arbitrary time, the control based on the second signal is continued when the first signal cannot be read.

90. The position control method according to claim 88, wherein the control based on the second signal is performed from a state in which the rotating body is stopped until the rotating body reaches steady drive, and the control is switched to control based on the first signal after the rotating body reaches the steady drive.

91. The position control method according to claim 88, wherein, when control is performed based on the first signal, the control is switched to control based on the second signal when the first signal cannot be read.

92. The position control method according to claim 88, wherein, when the first signal cannot be read and control is performed based on the second signal, the control is switched to control based on the first signal when it becomes possible to read the first signal.

93. The position control method according to claim 88, wherein, when a breaking part where the first signal breaks is present and control is performed based on the first signal, the control is switched to control based on the second signal in the breaking part, and the control is switched to the control based on the first signal again when the rotating body has passed the breaking part.

94. The position control method according to claim 89, wherein, when there is abnormality in a unit that reads the first signal, the unit outputs a signal informing the abnormality to a control side.

95. The position control method according to claim 91, wherein, when there is abnormality in a unit that reads the first signal, the unit outputs a signal informing the abnormality to a control side.

96. The position control method according to claim 92, wherein, when there is abnormality in a unit that reads the first signal, the unit outputs a signal informing the abnormality to a control side.

97. The position control method according to claim 89, wherein, when a normal signal is not recognized on a control side in an arbitrary time section with respect to a signal from a unit that reads the first signal, the control side outputs a control signal equivalent to the first signal.

98. The position control method according to claim 91, wherein, when a normal signal is not recognized on a control side in an arbitrary time section with respect to a signal from a unit that reads the first signal, the control side outputs a control signal equivalent to the first signal.

99. The position control method according to claim 92, wherein, when a normal signal is not recognized on a control side in an arbitrary time section with respect to a signal from a unit that reads the first signal;

the control side outputs a control signal equivalent to the first signal.

100. The position control method according to claim 88, wherein, in switching a control signal, the switching is performed after applying correction processing equivalent to a difference between a position, which is obtained from control signal to be used after the switching, and a target position to the control signal to be used after the switching.

101. The position control method according to claim 88, wherein, in switching a control signal, the switching is performed after applying correction processing equivalent to a difference between a position, which is obtained from control signal to be used after the switching, and a position, which is obtained from a control signal used before the switching, to the control signal to be used after the switching.

102. The position control method according to claim 88, wherein the first signal is a scale pulse based on a scale provided in the rotating body, and the second signal is a signal from an encoder provided in a shaft of the rotating body.

103. A position control device that controls position of a rotating body, comprising:

a first signal generating unit that is provided in a rotating body driven to rotate by a drive source and generates a first signal for detecting displacement in a rotating direction of the rotating body;

a second signal generating unit that is provided in a shaft of the rotating body and generates a second signal for detecting displacement in a rotating direction of the shaft; and

a control unit that controls the drive source based on the signal generated by the first signal generating unit or the second signal generating unit, wherein

the control unit uses the two signals as a control signal selectively.

104. The position control device according to claim 103, wherein, when control is performed based on the second signal, in switching the control to control based on the first signal at arbitrary time, the control unit continues the control based on the second signal when the first signal cannot be read.

105. The position control device according to claim 103, wherein the control based on the second signal is performed from a state in which the rotating body is stopped until the rotating body reaches steady drive, and the control is switched to control based on the first signal after the rotating body reaches the steady drive.

106. The position control device according to claim 103, wherein, when control is performed based on the first signal, the control is switched to control based on the second signal when the first signal cannot be read.

107. The position control device according to claim 103, wherein, when the first signal cannot be read and control is performed based on the second signal, the control is switched to control based on the first signal when it becomes possible to read the first signal.

108. The position control device according to claim 103, wherein, when a breaking part where the first signal breaks is present and control is performed based on the first signal, the control is switched to control based on the second signal in the breaking part, and the control is switched to the control based on the first signal again when the rotating body has passed the breaking part.

109. The position control device according to claim 104, wherein, when there is abnormality in a unit that reads the first signal, the unit outputs a signal informing the abnormality to a control side.

110. The position control device according to claim 106, wherein, when there is abnormality in a unit that reads the first signal, the unit outputs a signal informing the abnormality to a control side.

111. The position control device according to claim 107, wherein, when there is abnormality in a unit that reads the first signal, the unit outputs a signal informing the abnormality to a control side.

112. The position control device according to claim 104, wherein, when a normal signal is not recognized on a control side in an arbitrary time section with respect to a signal from a unit that reads the first signal, the control side outputs a control signal equivalent to the first signal.

113. The position control device according to claim 106, wherein, when a normal signal is not recognized on a control side in an arbitrary time section with respect to a signal from a unit that reads the first signal, the control side outputs a control signal equivalent to the first signal.

114. The position control device according to claim 107, wherein, when a normal signal is not recognized on a control side in an arbitrary time section with respect to a signal from a unit that reads the first signal, the control side outputs a control signal equivalent to the first signal.

115. The position control device according to claim 103, wherein, in switching a control signal, the switching is performed after applying correction processing equivalent to a difference between a position, which is obtained from control signal to be used after the switching, and a target position to the control signal to be used after the switching.

116. The position control device according to claim 103, wherein, in switching a control signal, the switching is performed after applying correction processing equivalent to a difference between a position, which is obtained from control signal to be used after the switching, and a position, which is obtained from a control signal used before the switching, to the control signal to be used after the switching.

117. The position control device according to claim 103, wherein

the first signal generating unit includes a scale provided in the rotating body and a reflective photo-sensor that reads the scale,

the first signal is a scale pulse,

the second signal generating unit includes an encoder provided in a shaft of the rotating body, and

the second signal is a signal from the encoder.

118. An image forming apparatus comprising:

an image bearing member on which an image is formed; and

a position control device that drive controls the image bearing member and includes

a first signal generating unit that is provided in a rotating body driven to rotate by a drive source and generates a first signal for detecting displacement in a rotating direction of the rotating body;

a second signal generating unit that is provided in a shaft of the rotating body and generates a second signal for detecting displacement in a rotating direction of the shaft; and

a control unit that controls the drive source based on the signal generated by the first signal generating unit or the second signal generating unit, wherein

the control unit uses the two signals as a control signal selectively.

119. The image forming apparatus according to claim 118, wherein the mage bearing member is a photosensitive drum.

120. The image forming apparatus according to claim 118, wherein the image bearing member is a photosensitive belt.

121. The image forming apparatus according to claim 118, wherein the image bearing member is a transfer drum.

122. The image forming apparatus according to claim 118, wherein the image bearing member is an intermediate transfer belt.

123. The image forming apparatus according to claim 118, wherein the image bearing member is a direct transfer belt.

124. The image forming apparatus according to claim 118, further comprising a recording medium that is detachably connected to a control unit actuating the apparatus and in which a computer program for controlling a rotating body is recorded, wherein

position control for the image bearing member is performed by the computer program for a rotating body recorded in the recording medium.

125. The image forming apparatus according to claim 118,

wherein a control unit actuating the apparatus is provided to be connectable to a communication network, and

position control for the image bearing member is performed by the computer program for controlling the rotating body captured from a server on the communication network.

126. The image forming apparatus according to claim 118, further comprising a display unit that, when the first signal generating unit breaks down, informs a user that the first signal generating unit has broken down.

127. The image forming apparatus according to claim 118, further comprising a display unit that, when the first signal generating unit breaks down and revives thereafter, informs a user that the first signal generating unit has revived.

128. An image forming apparatus comprising:

a plurality of image bearing members on which an image is formed respectively; and

a position control device that drive controls at least one of the image bearing members and includes

a first signal generating unit that is provided in a rotating body driven to rotate by a drive source and generates a first signal for detecting displacement in a rotating direction of the rotating body;

a second signal generating unit that is provided in a shaft of the rotating body and generates a second signal for detecting displacement in a rotating direction of the shaft; and

a control unit that controls the drive source based on the signal generated by the first signal generating unit or the second signal generating unit, wherein

the control unit uses the two signals as a control signal selectively.

129. The image forming apparatus according to claim 128, further comprising a recording medium that is detachably connected to a control unit actuating the apparatus and in which a computer program for controlling a rotating body is recorded, wherein

position control for the image bearing member is performed by the computer program for a rotating body recorded in the recording medium.

130. The image forming apparatus according to claim 128,

wherein a control unit actuating the apparatus is provided to be connectable to a communication network, and

position control for the image bearing member is performed by the computer program for controlling the rotating body captured from a server on the communication network.

131. The image forming apparatus according to claim 128, further comprising a display unit that, when the first signal generating unit breaks down, informs a user that the first signal generating unit has broken down.

132. The image forming apparatus according to claim 128, further comprising a display unit that, when the first signal generating unit breaks down and revives thereafter, informs a user that the first signal generating unit has revived.

133. An image reading apparatus comprising:

a traveling body drive device that reads an image; and

a position control device that drive controls the traveling body drive device and includes

a first signal generating unit that is provided in a rotating body driven to rotate by a drive source and generates a first signal for detecting displacement in a rotating direction of the rotating body;

a second signal generating unit that is provided in a shaft of the rotating body and generates a second signal for detecting displacement in a rotating direction of the shaft; and

a control unit that controls the drive source based on the signal generated by the first signal generating unit or the second signal generating unit, wherein

the control unit uses the two signals as a control signal selectively.

134. The image reading apparatus according to claim 133, further comprising a display unit that, when the first signal generating unit breaks down, informs a user that the first signal generating unit has broken down.

135. The image forming apparatus according to claim 133, further comprising a display unit that, when the first signal generating unit breaks down and revives thereafter, informs a user that the first signal generating unit has revived.

136. A computer readable recording medium with a computer program stored therein that causes a computer to realize a position control method for controlling displacement in a rotating direction of a rotating body, which is driven to rotate by a drive source, by reading signals generated according to rotation of the rotating body, wherein

the signals are two kinds of signals, namely, a first signal generated by rotation of the rotating body itself and a second signal generated by rotation of a shaft of the rotating body, and these two signals are used as a control signal selectively.

137. A drive control device comprising:

a mark detecting unit that detects plural marks that are provided on a drive control object member at predetermined interval along a direction of movement of the drive control object member, or that detects plural marks that are provided on an endless moving member at predetermined interval along a direction of movement of the endless moving member, wherein the drive control object member and the endless moving member move endlessly, wherein the mark detecting unit outputs a mark detection signal when a mark is detected;

a multiplying unit that generates a multiplied signal by increasing by a predetermined times a magnitude of the mark detection signal; and

a feedback control unit that performs feedback control using the multiplied signal when it is judged that a discontinuous part, where intervals of signal parts corresponding to the marks are outside a range decided in advance, is not present in the mark detection signal or the multiplied signal and performs the feedback control using an alternative signal instead of the multiplied signal when it is judged that the discontinuous part is present.

138. The drive control device according to claim 137, wherein a multiplying circuit, which compares phases of the feedbacked multiplied signal and the mark detection signal before multiplication and generates a multiplied signal using a result of the phase comparison, is used as the multiplying unit.

139. The drive control device according to claim 137, further comprising a control switching unit that performs switching processing for switching selection concerning whether to cause the feedback control unit to perform the feedback control using the multiplied signal or to perform the feedback control using the alternative signal, wherein

a period, in which the feedback control unit is caused to perform the feedback control using the alternative signal by the control switching unit, is set as a period obtained by adding an operation stable period, which is set to be equal to or longer than time necessary for a multiplying operation by the multiplying unit is made stable, to a period from the time when it is judged that the discontinuous part is present until the time when it is judged that the discontinuous part is not present.

140. The drive control device according to claim 139, wherein

the judgment on whether the discontinuous part is present is performed according to whether the number of signal parts corresponding to the marks in the mark detection signal or the multiplied signal obtained within predetermined sampling time is smaller than a defined number, and

the operation stable period is set to a period equivalent to a period integer times as long as the sampling time.

141. The drive control device according to claim 139, further comprising a program storing medium having stored therein a computer program for causing a computer, which functions as the feedback control unit, to function as the control switching unit, wherein

the computer performs the switching processing by executing the computer program.

142. The drive control device according to claim 139,

wherein the control switching unit performs the switching processing by sending a switching signal to the feedback control unit.

143. A drive control method comprising:

detecting plural marks that are provided on a drive control object member at predetermined interval along a direction of movement of the drive control object member, or that detects plural marks that are provided on an endless moving member at predetermined interval along a direction of movement of the endless moving member, wherein the drive control object member and the endless moving member move endlessly;

outputing a mark detection signal when a mark is detected and the mark detection signal

generating a multiplied signal by increasing by a predetermined times a magnitude of the mark detection signal; and

performing feedback control using the multiplied signal when it is judged that a discontinuous part, where intervals of signal parts corresponding to the marks are outside a range decided in advance, is not present in the mark detection signal or the multiplied signal and performs the feedback control using an alternative signal instead of the multiplied signal when it is judged that the discontinuous part is present.

144. An image forming apparatus comprising:

a drive control object member that moves endlessly; and

a drive control device that drive controls the drive control object member and includes

a mark detecting unit that detects plural marks that are provided on a drive control object member at predetermined interval along a direction of movement of the drive control object member, or that detects plural marks that are provided on an endless moving member at predetermined interval along a direction of movement of the endless moving member, wherein the drive control object member and the endless moving member move endlessly, wherein the mark detecting unit outputs a mark detection signal when a mark is detected;

a multiplying unit that generates a multiplied signal by increasing by a predetermined times a magnitude of the mark detection signal; and

a feedback control unit that performs feedback control using the multiplied signal when it is judged that a discontinuous part, where intervals of signal parts corresponding to the marks are outside a range decided in advance, is not present in the mark detection signal or the multiplied signal and performs the feedback control using an alternative signal instead of the multiplied signal when it is judged that the discontinuous part is present.

145. An image reading apparatus comprising:

a traveling body that irradiates light on an original surface or receives reflected light of light irradiated on the original surfaced;

a drive control object member, which moves endlessly, provided on a drive force transmission path for transmitting a drive force for causing the traveling member to travel along the original surface; and

a drive control device that drive controls the drive control object member and includes

a mark detecting unit that detects plural marks that are provided on a drive control object member at predetermined interval along a direction of movement of the drive control object member, or that detects plural marks that are provided on an endless moving member at predetermined interval along a direction of movement of the endless moving member, wherein the drive control object member and the endless moving member move endlessly, wherein the mark detecting unit outputs a mark detection signal when a mark is detected;

a multiplying unit that generates a multiplied signal by increasing by a predetermined times a magnitude of the mark detection signal; and

a feedback control unit that performs feedback control using the multiplied signal when it is judged that a discontinuous part, where intervals of signal parts corresponding to the marks are outside a range decided in advance, is not present in the mark detection signal or the multiplied signal and performs the feedback control using an alternative signal instead of the multiplied signal when it is judged that the discontinuous part is present.

146. A computer program that realizes a drive control method on a computer, wherein the drive control method includes

detecting plural marks that are provided on a drive control object member at predetermined interval along a direction of movement of the drive control object member, or that detects plural marks that are provided on an endless moving member at predetermined interval along a direction of movement of the endless moving member, wherein the drive control object member and the endless moving member move endlessly;

outputing a mark detection signal when a mark is detected and the mark detection signal;

generating a multiplied signal by increasing by a predetermined times a magnitude of the mark detection signal; and

performing feedback control using the multiplied signal when it is judged that a discontinuous part, where intervals of signal parts corresponding to the marks are outside a range decided in advance, is not present in the mark detection signal or the multiplied signal and performs the feedback control using an alternative signal instead of the multiplied signal when it is judged that the discontinuous part is present.

147. A drive control device comprising:

a mark detecting unit that detects plural marks that are provided on a drive control object member at predetermined interval along a direction of movement of the drive control object member, or that detects plural marks that are provided on an endless moving member at predetermined interval along a direction of movement of the endless moving member, wherein the drive control object member and the endless moving member move endlessly, wherein the mark detecting unit outputs a mark detection signal when a mark is detected;

a feedback control unit that performs feedback control using an alternative signal instead of the mark detection signal at least for one of a discontinuous part in the mark detection signal where intervals of signal parts corresponding to the respective marks are outside a range decided in advance and signal parts immediately before and after the discontinuous part.

148. The drive control device according to claim 147, wherein

the signal parts, for which the feedback control using the alternative signal is set such that all unstable signal parts present in at least one of a part immediately before and a part immediately after the discontinuous part are included in the signal parts.

149. The drive control device according to claim 147, further comprising a specific control signal output unit that outputs a specific control signal in a discontinuous period, in which the discontinuous part is present in the mark detection signal, and a fixed period decided in advance immediately after the period, wherein

the feedback control unit performs the feedback control using the alternative signal while the specific control signal is output.

150. The drive control device according to claim 147, further comprising a specific control signal output unit that outputs a specific control signal in a discontinuous period, in which the discontinuous part is present in the mark detection signal, and a fixed period decided in advance immediately before the period, wherein

the feedback control unit performs the feedback control using the alternative signal while the specific control signal is output.

151. The drive control device according to claim 147, further comprising a specific control signal output unit that outputs a specific control signal in a discontinuous period, in which the discontinuous part is present in the mark detection signal, a fixed period decided in advance immediately after the period, and a fixed period decided in advance immediately before the period, wherein

the feedback control unit performs the feedback control using the alternative signal while the specific control signal is output.

152. The drive control device according to claim 150, further comprising a storing unit that stores start time of the discontinuous part in the mark detection signal, wherein

when the discontinuous part appears in the mark detection signal next time or after the next time, the specific control signal output unit starts output of the specific control signal the fixed period before the start time stored in the storing unit.

153. The drive control device according to claim 149, further comprising a velocity detecting unit that detects endless moving velocity of the drive control object member or the endless moving member, wherein

whether the discontinuous part is present depends on whether the endless moving velocity detected by the velocity detecting unit is outside a defined range.

154. The drive control device according to claim 149, wherein

start time and end time of the discontinuous period are set to timing at which a signal, which is obtained by removing a frequency component equivalent to time intervals of signal parts corresponding to the respective mark from the mark detection signal, changes across a predetermined threshold value.

155. The drive control device according to claim 149, wherein

whether the discontinuous part is present depend on whether the number of signal parts corresponding to marks in the mark detection signal obtained within predetermined sampling time is smaller than a defined number, and

the fixed period is set to time equivalent to time integer times as long as the sampling time.

156. The drive control device according to claim 147, further comprising a multiplying unit that generates a multiplied signal obtained by multiplying the mark detection signal to be predetermined times as large, wherein

the feedback control unit performs the feedback control using the multiplied signal in periods other than the period in which the feedback control unit performs the feedback control using the alternative signal.

157. The drive control device according to claim 156, wherein

a multiplying circuit, which compares phases of the feedbacked multiplied signal and the mark detection signal before multiplication and generates a multiplied signal using a result of the phase comparison, is used as the multiplying unit.

158. A drive control method comprising:

detecting plural marks that are provided on a drive control object member at predetermined interval along a direction of movement of the drive control object member, or that detects plural marks that are provided on an endless moving member at predetermined interval along a direction of movement of the endless moving member, wherein the drive control object member and the endless moving member move endlessly;

outputing a mark detection signal when a mark is detected and the mark detection signal; and

performing feedback control using an alternative signal instead of the mark detection signal at least for one of a discontinuous part in the mark detection signal where intervals of signal parts corresponding to the respective marks are outside a range decided in advance and signal parts immediately before and after the discontinuous part.

159. An image forming apparatus comprising:

a drive control object member that moves endlessly; and

a drive control device that drive controls the drive control object member, wherein the drive control device includes

a mark detecting unit that detects plural marks that are provided on a drive control object member at predetermined interval along a direction of movement of the drive control object member, or that detects plural marks that are provided on an endless moving member at predetermined interval along a direction of movement of the endless moving member, wherein the drive control object member and the endless moving member move endlessly, wherein the mark detecting unit outputs a mark detection signal when a mark is detected;

a feedback control unit that performs feedback control using an alternative signal instead of the mark detection signal at least for one of a discontinuous part in the mark detection signal where intervals of signal parts corresponding to the respective marks are outside a range decided in advance and signal parts immediately before and after the discontinuous part.

160. An image reading apparatus comprising:

a traveling body that irradiates light on an original surface or receives reflected light of light irradiated on the original surfaced;

a drive control object member, which moves endlessly, provided on a drive force transmission path for transmitting a drive force for causing the traveling member to travel along the original surface; and

a drive control device that drive controls the drive control object member, wherein the drive control device includes

a mark detecting unit that detects plural marks that are provided on a drive control object member at predetermined interval along a direction of movement of the drive control object member, or that detects plural marks that are provided on an endless moving member at predetermined interval along a direction of movement of the endless moving member, wherein the drive control object member and the endless moving member move endlessly, wherein the mark detecting unit outputs a mark detection signal when a mark is detected;

a feedback control unit that performs feedback control using an alternative signal instead of the mark detection signal at least for one of a discontinuous part in the mark detection signal where intervals of signal parts corresponding to the respective marks are outside a range decided in advance and signal parts immediately before and after the discontinuous part.

161. A computer program that realizes a drive control method on a computer, the drive control method including

detecting plural marks that are provided on a drive control object member at predetermined interval along a direction of movement of the drive control object member, or that detects plural marks that are provided on an endless moving member at predetermined interval along a direction of movement of the endless moving member, wherein the drive control object member and the endless moving member move endlessly;

outputing a mark detection signal when a mark is detected and the mark detection signal; and

performing feedback control using an alternative signal instead of the mark detection signal at least for one of a discontinuous part in the mark detection signal where intervals of signal parts corresponding to the respective marks are outside a range decided in advance and signal parts immediately before and after the discontinuous part.