ELECTRONIC STYLUS, CAPACITIVE TOUCHPAD MODULE, AND APPARATUS FOR TOUCH INPUT

• US 20100170726A1
• Filed: 01/04/2010
• Published: 07/08/2010
• Est. Priority Date: 01/06/2009
• Status: Active Grant

• Current Assignee: Elan Microelectronics Corporation
• Original Assignee: Elan Microelectronics Corporation
• Inventors: WANG, TSUN-MIN, HUANG, HUNG-MING, CHENG, CHUNG-HAN, YEH, CHI-TEIN, HUANG, CHUN-CHUNG, YEH, I-HAU
• Granted Patent: US 8,564,553 B2
• Time in Patent Office: Days
• US Class Current: 178/19.30
• CPC Class Codes: G06F 3/03545 Pens or stylus
• CPC Class Codes: G06F 3/0441 using active external devices, e.g. active pens, for receiving changes in electrical potential transmitted by the digitiser, e.g. tablet driving signals
• CPC Class Codes: G06F 3/0442 using active external devices, e.g. active pens, for transmitting changes in electrical potential to be received by the digitiser
• CPC Class Codes: G06F 3/0446 using a grid-like structure of electrodes in at least two directions, e.g. using row and column electrodes

Abstract

An electronic stylus emits an excitation signal to apply to a trace of a capacitive touchpad module near a touch point when the electronic stylus touches the capacitive touchpad module, so as to change a waveform of a charging/discharging signal in the trace, and depending on the waveform variation, the capacitive touchpad module can identify the touch point.

Claims

1. An apparatus for touch input, comprising:

a capacitive touchpad module; and

an electronic stylus for emitting an excitation signal to apply to a trace of the capacitive touchpad module near a touch point when the electronic stylus touches the capacitive touchpad module, so as to change a waveform of a charging/discharging signal in the trace.

2. The apparatus of claim 1, wherein the excitation signal has a frequency which is an integral multiple of that of the charging/discharging signal.

3. The apparatus of claim 1, wherein the excitation signal has a constant phase difference from the charging/discharging signal.

4. The apparatus of claim 1, wherein the excitation signal has a frequency equal to that of the charging/discharging signal and a duty ratio of 50%.

5. The apparatus of claim 1, wherein the excitation signal has a frequency equal to one half of that of the charging/discharging signal and a duty ratio of 25%.

6. The apparatus of claim 1, wherein the excitation signal has a frequency equal to one third of that of the charging/discharging signal and a duty ratio of 16.7%.

7. The apparatus of claim 1, wherein the excitation signal has a frequency equal to one quarter of that of the charging/discharging signal and a duty ratio of 12.5%.

8. The apparatus of claim 1, wherein the electronic stylus comprises:

an oscillation circuit for generating the excitation signal;

a power circuit connected to the oscillation circuit, for providing a supply voltage for the oscillation circuit; and

a tip connected to the oscillation circuit for emitting the excitation signal.

9. The apparatus of claim 8, wherein the oscillation circuit comprises:

a quartz oscillator for generating the excitation signal; and

a boost circuit connected between the power circuit and the quartz oscillator, for boosting the supply voltage to be a boosted voltage applied to the quartz oscillator to drive the quartz oscillator.

10. The apparatus of claim 8, wherein the power circuit generates the supply voltage according to a radio frequency signal transmitted from the capacitive touchpad module.

11. The apparatus of claim 8, wherein the power circuit transforms a magnetic force into the supply voltage.

12. The apparatus of claim 8, wherein the power circuit comprises a battery for providing the supply voltage.

13. The apparatus of claim 8, wherein the electronic stylus further comprises a switch controlling whether or not to emit the excitation signal.

14. The apparatus of claim 8, wherein the tip comprises a metal.

15. The apparatus of claim 8, wherein the tip comprises a flexible conductor.

16. The apparatus of claim 8, wherein the tip comprises a metal wrapped by a nonconductor.

17. The apparatus of claim 8, wherein the electronic stylus further comprises:

a metal wrapping around the tip;

a first insulator wrapping around the metal for shielding against ambient interference; and

a second insulator between the tip and the metal for separating the tip from the metal.

18. The apparatus of claim 1, wherein the capacitive touchpad module comprises:

an output terminal; and

a detection circuit connected to the trace for detecting the charging/discharging signal from the trace to generate the excitation signal, which is related to a phase and a frequency of the charging/discharging signal, for being transmitted to the electronic stylus via the output terminal and a signal line.

19. The apparatus of claim 18, wherein the electronic stylus comprises:

an input terminal connected to the output terminal via the signal line; and

a tip connected to the input terminal for emitting the excitation signal.

20. The apparatus of claim 19, wherein the tip comprises a metal.

21. The apparatus of claim 19, wherein the tip comprises a flexible conductor.

22. The apparatus of claim 19, wherein the tip comprises a metal wrapped by a nonconductor.

23. The apparatus of claim 19, wherein the electronic stylus further comprises:

a metal wrapping around the tip and connected to a ground line of the capacitive touchpad module;

a first insulator wrapping around the metal for shielding against ambient interference; and

a second insulator between the tip and the metal for separating the tip from the metal.

24. The apparatus of claim 1, wherein the capacitive touchpad module comprises:

a detection circuit connected to the trace for detecting the charging/discharging signal from the trace to generate a detection signal which is related to a phase and a frequency of the charging/discharging signal;

an up-converter circuit connected to the detection circuit for up-converting the detection signal to generate a high-frequency signal; and

a transceiver system connected to the up-converter circuit for transmitting the high-frequency signal to the electronic stylus.

25. The apparatus of claim 24, wherein the electronic stylus comprises:

a down-converter circuit for receiving and down-converting the high-frequency signal to generate the excitation signal which is related to the phase and the frequency of the charging/discharging signal; and

a tip connected to the down-converter circuit for emitting the excitation signal.

26. The apparatus of claim 25, wherein the tip comprises a metal.

27. The apparatus of claim 25, wherein the tip comprises a flexible conductor.

28. The apparatus of claim 25, wherein the tip comprises a metal wrapped by a nonconductor.

29. The apparatus of claim 25, wherein the electronic stylus further comprises:

a metal wrapping around the tip;

a first insulator wrapping around the metal for shielding against ambient interference; and

a second insulator between the tip and the metal for separating the tip from the metal.

30. The apparatus of claim 1, wherein the capacitive touchpad module comprises:

a detection circuit connected to the trace for detecting the charging/discharging signal from the trace to generate a detection signal which is related to a phase and a frequency of the charging/discharging signal;

a modulation circuit connected to the detection circuit for modulating the detection signal to generate a carrier; and

a transceiver system connected to the modulation circuit for transmitting the carrier to the electronic stylus.

31. The apparatus of claim 30, wherein the electronic stylus comprises:

a demodulation circuit for receiving and demodulating the carrier to generate the excitation signal which is related to the phase and the frequency of the charging/discharging signal; and

a tip connected to the demodulation circuit for emitting the excitation signal to the capacitive touchpad module.

32. The apparatus of claim 31, wherein the tip comprises a metal.

33. The apparatus of claim 31, wherein the tip comprises a flexible conductor.

34. The apparatus of claim 31, wherein the tip comprises a metal wrapped by a nonconductor.

35. The apparatus of claim 31, wherein the electronic stylus further comprises:

a metal wrapping around the tip;

a first insulator wrapping around the metal for shielding against ambient interference; and

a second insulator between the tip and the metal for separating the tip from the metal.

36. The apparatus of claim 1, wherein the capacitive touchpad module comprises:

a detection circuit connected to the trace for detecting the charging/discharging signal from the trace to generate a detection signal which is related to a phase and a frequency of the charging/discharging signal;

a modulation circuit connected to the detection circuit for embedding data into a carrier according to the detection signal; and

a transceiver system connected to the modulation circuit for transmitting the carrier to the electronic stylus.

37. The apparatus of claim 36, wherein the electronic stylus comprises:

a demodulation circuit for receiving and demodulating the carrier to generate the excitation signal which is related to the phase and the frequency of the charging/discharging signal; and

a tip connected to the demodulation circuit for emitting the excitation signal.

38. The apparatus of claim 37, wherein the tip comprises a metal.

39. The apparatus of claim 37, wherein the tip comprises a flexible conductor.

40. The apparatus of claim 37, wherein the tip comprises a metal wrapped by a nonconductor.

41. The apparatus of claim 37, wherein the electronic stylus further comprises:

a metal wrapping around the tip;

a first insulator wrapping around the metal for shielding against ambient interference; and

a second insulator between the tip and the metal for separating the tip from the metal.

42. A control method for an apparatus including an electronic stylus and a capacitive touchpad module for touch input, the control method comprising:

providing an excitation signal for the electronic stylus;

emitting the excitation signal by the electronic stylus to apply to a trace of the capacitive touchpad module near a touch point when the electronic stylus touches the capacitive touchpad module, so as to change a waveform of a charging/discharging signal in the trace; and

sensing the touch point according to a variation of the waveform.

43. The control method of claim 42, wherein the excitation signal has a frequency equal to an integral multiple of that of the charging/discharging signal.

44. The control method of claim 42, wherein the excitation signal has a constant phase difference from the charging/discharging signal.

45. The control method of claim 42, wherein the excitation signal has a frequency equal to that of the charging/discharging signal and a duty ratio of 50%.

46. The control method of claim 42, wherein the excitation signal has a frequency equal to one half of that of the charging/discharging signal and a duty ratio of 25%.

47. The control method of claim 42, wherein the excitation signal has a frequency equal to one third of that of the charging/discharging signal and a duty ratio of 16.7%.

48. The control method of claim 42, wherein the excitation signal has a frequency equal to one quarter of that of the charging/discharging signal and a duty ratio of 12.5%.

49. The control method of claim 42, further comprising the step of generating the excitation signal by an oscillation circuit.

50. The control method of claim 42, wherein the step of providing an excitation signal for the electronic stylus comprises:

detecting the charging/discharging signal from the trace for generating a detection signal;

up-converting the detection signal for generating a high-frequency signal;

transmitting the high-frequency signal to the electronic stylus; and

receiving and down-converting the high-frequency signal for generating the excitation signal which is related to a phase and a frequency of the charging/discharging signal.

51. The control method of claim 42, wherein the step of providing an excitation signal for the electronic stylus comprises:

detecting the charging/discharging signal from the trace for generating a detection signal;

modulating the detection signal for generating a carrier;

transmitting the carrier to the electronic stylus; and

receiving and demodulating the carrier for generating the excitation signal which is related to a phase and a frequency of the charging/discharging signal.

52. The control method of claim 42, wherein the step of providing an excitation signal for the electronic stylus comprises:

detecting the charging/discharging signal from the trace for generating a detection signal which is related to a phase and a frequency of the charging/discharging signal;

embedding data into a carrier according to the detection signal;

transmitting the carrier to the electronic stylus;

extracting the data from the carrier; and

according to the data, generating the excitation signal which is related to the phase and the frequency of the charging/discharging signal.

53. An electronic stylus for touch input to a capacitive touchpad module, comprising:

an oscillation circuit for generating an excitation signal;

a power circuit connected to the oscillation circuit for providing a supply voltage for the oscillation circuit; and

a tip connected to the oscillation circuit for emitting the excitation signal to apply to a trace of the capacitive touchpad module near a touch point when the electronic stylus touches the capacitive touchpad module, so as to change a waveform of a charging/discharging signal in the trace.

54. The electronic stylus of claim 53, wherein the oscillation circuit comprises:

a boost circuit connected to the power circuit for boosting the supply voltage to generate a boosted voltage; and

a quartz oscillator connected to the boost circuit for being driven by the boosted voltage to generate the excitation signal.

55. The electronic stylus of claim 53, wherein the power circuit generates the supply voltage according to a radio frequency signal transmitted from the capacitive touchpad module.

56. The electronic stylus of claim 53, wherein the power circuit transforms a magnetic force into the supply voltage.

57. The electronic stylus of claim 53, wherein the power circuit comprises a battery for providing the supply voltage.

58. The electronic stylus of claim 53, further comprising a switch for controlling whether or not to emit the excitation signal.

59. The electronic stylus of claim 53, wherein the tip comprises a metal.

60. The electronic stylus of claim 53, wherein the tip comprises a flexible conductor.

61. The electronic stylus of claim 53, wherein the tip comprises a metal wrapped by a nonconductor.

62. The electronic stylus of claim 53, further comprising:

a metal wrapping around the tip;

a first insulator wrapping around the metal for shielding against ambient interference; and

a second insulator between the tip and the metal for separating the tip from the metal.

63. The electronic stylus of claim 53, wherein the excitation signal has a frequency equal to an integral multiple of that of the charging/discharging signal.

64. The electronic stylus of claim 53, wherein the excitation signal has a constant phase difference from the charging/discharging signal.

65. The electronic stylus of claim 53, wherein the excitation signal has a frequency equal to that of the charging/discharging signal and a duty ratio of 50%.

66. The electronic stylus of claim 53, wherein the excitation signal has a frequency equal to one half of that of the charging/discharging signal and a duty ratio of 25%.

67. The electronic stylus of claim 53, wherein the excitation signal has a frequency equal to one third of that of the charging/discharging signal and a duty ratio of 16.7%.

68. The electronic stylus of claim 53, wherein the excitation signal has a frequency equal to one quarter of that of the charging/discharging signal and a duty ratio of 12.5%.

69. An electronic stylus for touch input to a capacitive touchpad module, comprising:

an input terminal connected to the capacitive touchpad module via a signal line for receiving an excitation signal from the capacitive touchpad module; and

a tip connected to the input terminal for emitting the excitation signal to apply to a trace of the capacitive touchpad module near a touch point when the electronic stylus touches the capacitive touchpad module, so as to change a waveform of a charging/discharging signal in the trace.

70. The electronic stylus of claim 69, wherein the tip comprises a metal.

71. The electronic stylus of claim 69, wherein the tip comprises a flexible conductor.

72. The electronic stylus of claim 69, wherein the tip comprises a metal wrapped by a nonconductor.

73. The electronic stylus of claim 69, further comprising:

a metal wrapping around the tip and connected to a ground line of the capacitive touchpad module;

a first insulator wrapping around the metal for shielding against ambient interference; and

a second insulator between the tip and the metal for separating the tip from the metal.

74. The electronic stylus of claim 69, wherein the excitation signal has a frequency which is an integral multiple of that of the charging/discharging signal.

75. The electronic stylus of claim 69, wherein the excitation signal has a constant phase difference from the charging/discharging signal.

76. The electronic stylus of claim 69, wherein the excitation signal has a frequency equal to that of the charging/discharging signal and a duty ratio of 50%.

77. The electronic stylus of claim 69, wherein the excitation signal has a frequency equal to one half of that of the charging/discharging signal and a duty ratio of 25%.

78. The electronic stylus of claim 69, wherein the excitation signal has a frequency equal to one third of that of the charging/discharging signal and a duty ratio of 16.7%.

79. The electronic stylus of claim 69, wherein the excitation signal has a frequency equal to one quarter of that of the charging/discharging signal and a duty ratio of 12.5%.

80. An electronic stylus for touch input to a capacitive touchpad module, comprising:

a down-converter circuit for down-converting a signal transmitted from the capacitive touchpad module to generate an excitation signal; and

a tip connected to the down-converter circuit for emitting the excitation signal to apply to a trace of the capacitive touchpad module near a touch point when the electronic stylus touches the capacitive touchpad module, so as to change a waveform of a charging/discharging signal in the trace.

81. The electronic stylus of claim 80, wherein the tip comprises a metal.

82. The electronic stylus of claim 80, wherein the tip comprises a flexible conductor.

83. The electronic stylus of claim 80, wherein the tip comprises a metal wrapped by a nonconductor.

84. The electronic stylus of claim 80, further comprising:

a metal wrapping around the tip;

a first insulator wrapping around the metal for shielding against ambient interference; and

a second insulator between the tip and the metal for separating the tip from the metal.

85. The electronic stylus of claim 80, wherein the excitation signal has a frequency equal to an integral multiple of that of the charging/discharging signal.

86. The electronic stylus of claim 80, wherein the excitation signal has a constant phase difference from the charging/discharging signal.

87. The electronic stylus of claim 80, wherein the excitation signal has a frequency equal to that of the charging/discharging signal and a duty ratio of 50%.

88. The electronic stylus of claim 80, wherein the excitation signal has a frequency equal to one half of that of the charging/discharging signal and a duty ratio of 25%.

89. The electronic stylus of claim 80, wherein the excitation signal has a frequency equal to one third of that of the charging/discharging signal and a duty ratio of 16.7%.

90. The electronic stylus of claim 80, wherein the excitation signal has a frequency equal to one quarter of that of the charging/discharging signal and a duty ratio of 12.5%.

91. An electronic stylus for touch input to a capacitive touchpad module, comprising:

a demodulation circuit for demodulating a carrier transmitted from the capacitive touchpad module to generate an excitation signal; and

a tip connected to the demodulation circuit for emitting the excitation signal to apply to a trace of the capacitive touchpad module near a touch point when the electronic stylus touches the capacitive touchpad module, so as to change a waveform of a charging/discharging signal in the trace.

92. The electronic stylus of claim 91, wherein the tip comprises a metal.

93. The electronic stylus of claim 91, wherein the tip comprises a flexible conductor.

94. The electronic stylus of claim 91, wherein the tip comprises a metal wrapped by a nonconductor.

95. The electronic stylus of claim 91, further comprising:

a metal wrapping around the tip;

a first insulator wrapping around the metal for shielding against ambient interference; and

a second insulator between the tip and the metal for separating the tip from the metal.

96. The electronic stylus of claim 91, wherein the excitation signal has a frequency which is an integral multiple of that of the charging/discharging signal.

97. The electronic stylus of claim 91, wherein the excitation signal has a constant phase difference from the charging/discharging signal.

98. The electronic stylus of claim 91, wherein the excitation signal has a frequency equal to that of the charging/discharging signal and a duty ratio of 50%.

99. The electronic stylus of claim 91, wherein the excitation signal has a frequency equal to one half of that of the charging/discharging signal and a duty ratio of 25%.

100. The electronic stylus of claim 91, wherein the excitation signal has a frequency equal to one third of that of the charging/discharging signal and a duty ratio of 16.7%.

101. The electronic stylus of claim 91, wherein the excitation signal has a frequency equal to one quarter of that of the charging/discharging signal and a duty ratio of 12.5%.

102. The electronic stylus of claim 91, wherein the carrier comprises data related to the charging/discharging signal.

103. The electronic stylus of claim 91, wherein the carrier comprises a signal related to a frequency and a phase of the charging/discharging signal.

104. A method for an electronic stylus for touch input to a capacitive touchpad module, the method comprising:

applying the excitation signal to a tip of the electronic stylus; and

emitting the excitation signal from the tip to apply to a trace of the capacitive touchpad module near a touch point when the electronic stylus touches the capacitive touchpad module, so as to change a waveform of a charging/discharging signal in the trace.

105. The method of claim 104, wherein the excitation signal has a frequency which is an integral multiple of that of the charging/discharging signal.

106. The method of claim 104, wherein the excitation signal has a constant phase difference from the charging/discharging signal.

107. The method of claim 104, wherein the excitation signal has a frequency equal to that of the charging/discharging signal and a duty ratio of 50%.

108. The method of claim 104, wherein the excitation signal has a frequency equal to one half of that of the charging/discharging signal and a duty ratio of 25%.

109. The method of claim 104, wherein the excitation signal has a frequency equal to one third of that of the charging/discharging signal and a duty ratio of 16.7%.

110. The method of claim 104, wherein the excitation signal has a frequency equal to one quarter of that of the charging/discharging signal and a duty ratio of 12.5%.

111. The method of claim 104, further comprising the step of generating the excitation signal by an oscillation circuit.

112. The method of claim 104, further comprising:

from the capacitive touchpad module, receiving a high-frequency signal which is related to a phase and a frequency of the charging/discharging signal; and

generating the excitation signal according to the high-frequency signal.

113. The method of claim 104, further comprising:

from the capacitive touchpad module, receiving a carrier which is related to a phase and a frequency of the charging/discharging signal; and

demodulating the carrier for generating the excitation signal.

114. The method of claim 104, further comprising:

from the capacitive touchpad module, receiving a carrier which includes data related to a frequency and a phase of the charging/discharging signal;

extracting the data from the carrier; and

generating the excitation signal according to the data.

115. A capacitive touchpad module, comprising:

an output terminal;

a trace; and

a detection circuit connected to the trace for detecting a charging/discharging signal from the trace to generate an excitation signal, which is related to a phase and a frequency of the charging/discharging signal, to transmit to an electronic stylus via the output terminal.

116. The capacitive touchpad module of claim 115, wherein the excitation signal has a frequency which is an integral multiple of that of the charging/discharging signal.

117. The capacitive touchpad module of claim 115, wherein the excitation signal has a constant phase difference from the charging/discharging signal.

118. The capacitive touchpad module of claim 115, wherein the excitation signal has a frequency equal to that of the charging/discharging signal and a duty ratio of 50%.

119. The capacitive touchpad module of claim 115, wherein the excitation signal has a frequency equal to one half of that of the charging/discharging signal and a duty ratio of 25%.

120. The capacitive touchpad module of claim 115, wherein the excitation signal has a frequency equal to one third of that of the charging/discharging signal and a duty ratio of 16.7%.

121. The capacitive touchpad module of claim 115, wherein the excitation signal has a frequency equal to one quarter of that of the charging/discharging signal and a duty ratio of 12.5%.

122. A control method for a capacitive touchpad module, comprising:

detecting a charging/discharging signal from a trace of the capacitive touchpad module; and

generating an excitation signal, which is related to a phase and a frequency of the charging/discharging signal, for transmitting to an electronic stylus.

123. The control method of claim 122, wherein the excitation signal has a frequency which is an integral multiple of that of the charging/discharging signal.

124. The control method of claim 122, wherein the excitation signal has a constant phase difference from the charging/discharging signal.

125. The control method of claim 122, wherein the excitation signal has a frequency equal to that of the charging/discharging signal and a duty ratio of 50%.

126. The control method of claim 122, wherein the excitation signal has a frequency equal to one half of that of the charging/discharging signal and a duty ratio of 25%.

127. The control method of claim 122, wherein the excitation signal has a frequency equal to one third of that of the charging/discharging signal and a duty ratio of 16.7%.

128. The control method of claim 122, wherein the excitation signal has a frequency equal to one quarter of that of the charging/discharging signal and a duty ratio of 12.5%.

129. A capacitive touchpad module, comprising:

a trace;

a detection circuit connected to the trace for detecting a charging/discharging signal from the trace to generate a detection signal which is related to a frequency and a phase of the charging/discharging signal;

an up-converter circuit connected to the detection circuit for up-converting the detection signal to generate a high-frequency signal; and

a transceiver system connected to the up-converter circuit for transmitting the high-frequency signal to an electronic stylus.

130. A control method for a capacitive touchpad module, comprising:

detecting a charging/discharging signal from a trace of the capacitive touchpad module for generating a detection signal which is related to a frequency and a phase of the charging/discharging signal;

up-converting the detection signal for generating a high-frequency signal; and

transmitting the high-frequency signal to an electronic stylus.

131. A capacitive touchpad module, comprising:

a trace;

a detection circuit connected to the trace for detecting a charging/discharging signal from the trace to generate a detection signal which is related to a frequency and a phase of the charging/discharging signal;

a modulation circuit connected to the detection circuit for generating a carrier according to the detection signal; and

a transceiver system connected to the modulation circuit for transmitting the carrier to an electronic stylus.

132. The capacitive touchpad module of claim 131, wherein the modulation circuit modulates the detection signal for generating the carrier.

133. The capacitive touchpad module of claim 131, wherein the modulation circuit embeds data into the carrier according to the detection signal.

134. A control method for a capacitive touchpad module, comprising:

detecting a charging/discharging signal from a trace of the capacitive touchpad module for generating a detection signal which is related to a frequency and a phase of the charging/discharging signal;

modulating the detection signal for generating a carrier; and

transmitting the carrier to an electronic stylus.

135. A control method for a capacitive touchpad module, comprising:

detecting a charging/discharging signal from a trace of the capacitive touchpad module for generating a detection signal which is related to a frequency and a phase of the charging/discharging signal;

embedding data into a carrier according to the detection signal; and

transmitting the carrier to an electronic stylus.

136. A control method for a capacitive touchpad module, comprising:

detecting a charging/discharging signal from a trace of the capacitive touchpad module; and

determining either a finger or an electronic stylus touching the capacitive touchpad module, depending on an increase or a decrease of an analog-to-digital conversion value of the charging/discharging signal.

137. The control method of claim 136, wherein the step of determining either a finger or an electronic stylus touching the capacitive touchpad module comprises:

determining that, it is a finger touching the capacitive touchpad module if the analog-to-digital conversion value is increased; and

determining that it is an electronic stylus touching the capacitive touchpad module if the analog-to-digital conversion value is decreased.