Operator sensing circuit for disabling motor of power equipment

• US 20060273806A1
• Filed: 08/15/2006
• Published: 12/07/2006
• Est. Priority Date: 02/17/2004
• Status: Active Grant

• Current Assignee: Gustav Magenwirth GmbH & Co KG
• Original Assignee: Gustav Magenwirth GmbH & Co KG
• Inventors: Neidert, Markus, Kirchner, Markus, Sauter, Ralph, Mittmann, Bernhard
• Granted Patent: US 7,795,882 B2
• Time in Patent Office: Days
• US Class Current: 324/686
• CPC Class Codes: H03K 17/962 Capacitive touch switches
• CPC Class Codes: H03K 2217/960725 Charge-transfer

Abstract

An electrical characteristic in an operator-sensing circuit having a microcontroller that commands a charge sensor to send a sensor charge signal to a capacitive sensing element. The charge sensor outputs a corresponding raw data signal to the microcontroller that in turn sends a signal that disables the motor of a unit power equipment upon the absence of an operator'"'"'s hand on a hand-gripping surface of the equipment. Capacitive means for operating within a predetermined charge range that includes preselected values that designate hands-off and hands-on conditions on the hand-gripping surface. The capacitor charge range is effective to distinguish between the presence of an operator'"'"'s hand and foreign material on the gripping surface for avoiding a false hands-on-signal.

Claims

1. Operator sensing circuit for a hand-grip of a device comprising:

at least one capacitive sensing element incorporated in said hand-grip, having a capacity which is increased in a hands-on state of an operator'"'"'s hand on said hand-grip when compared with a hands-off state of said hand-grip,

a charge sensor detecting at least a capacity of said sensing element and generating a capacity signal value representing said detected capacity,

a controller connected to said charge sensor and receiving said capacity signal value,

said controller comparing said capacity signal value with a preselected hands-on threshold value in order to distinguish between a proper hands-on state which is present if the capacity signal value is below said hands-on threshold or a non-proper hands-on state, which is present if the capacity signal value is above said hands-on threshold.

2. Operator sensing circuit as defined in claim 1, wherein said controller when detecting the proper hands-on state enables full operation of said device.

3. Operator sensing circuit as defined in claim 1, wherein said controller when determining the presence of the non-proper hands-on state disables full operation of said device.

4. Operator sensing circuit as defined in claims 1, wherein said controller when determining the presence of the non-proper hands-on state reduces operation of said device to a safe operational state.

5. Operator sensing circuit as defined in claim 4, wherein said controller stops driving of a dangerous component of said device.

6. Operator sensing circuit as defined in claim 5, wherein said controller interrupts a drive train for said dangerous component of said device.

7. Operator sensing circuit as defined in claim 1, wherein in said controller a range of predefined operational values indicating proper operative conditions of said sensing element is stored and wherein said controller compares said capacity signal value with said range of predefined signal values in order to determine the presence of proper operative sensor conditions of said sensing element if said capacity signal value is within said range.

8. Operator sensing circuit as defined in claim 7, wherein said range of predefined signal values extends from a preselected stored upppermost limit value above said preselected hands-on threshold value and to a preselected stored lowermost limit value.

9. Operator sensing circuit as defined in claim 7, wherein said controller when determining the presence of proper operative sensor conditions enables full operation of said device.

10. Operator sensing circuit as defined in claim 7 wherein said controller when not determining the presence of proper operative sensor conditions disables full operation of said device.

11. Operator sensing circuit as defined in claim 7, wherein said controller when not determining proper operative sensor conditions reduces operation of said device to a safe operational state.

12. Operator sensing circuit as defined in claim 1, wherein said charge sensor detects a capacity of a capacitive reference simulator element and generates a reference signal value indicative of said capacity and wherein said controller receives said reference signal value and compares it with a preselected stored reference range in order to determine proper operative circuit conditions of said sensing circuit if said reference signal value is within said reference range.

13. Operator sensing circuit as defined in claim 12, wherein said controller when determining the presence of proper operative circuit conditions enables full operation of said device.

14. Operator sensing circuit as defined in claim 12, wherein said controller when not determining the presence of proper operative circuit conditions disables full operation of said device.

15. Operator sensing circuit as defined in claim 12, wherein said controller when not determining the presence of proper operative circuit conditions reduces operation of said device to a safe operational state.

16. Operator sensing circuit as defined in claim 1, wherein said charge sensor sequentially detects said capacity of said at least one sensing element and said reference simulator element.

17. Operator sensing circuit as defined in claim 16, wherein a first sensing element and a second sensing element are provided and wherein said charge sensor sequentially detects said capacity of said first sensing element and said second sensing element.

18. Operator sensing circuit as defined in claim 16, wherein said charge sensor is sequentially connected to said at least one sensing element and said reference simulator element by a multiplexer.

19. Operator sensing circuit as defined in claim 16, wherein said multiplexer is controlled by said microcontroller.

20. Operator sensing circuit as defined in claim 1 wherein said capacitive sensing element comprises a first electrode arranged on an inner dielectric member, said inner dielectric member being disposed on a second electrode, and said first electrode being covered by an outer dielectric member.

21. Operator sensing circuit as defined in claim 20, wherein said first electrode has tube-like structural configuration.

22. Operator sensing circuit as defined in claim 21, wherein said tube-like structural configuration extends between opposed edges in direction of its axis with an extension which is smaller than the extension of an operator'"'"'s hand in this direction when gripping said hand-grip.

23. Operator sensing circuit as defined in claim 20 wherein said first electrode comprises a conductive foil.

24. Operator sensing circuit as defined in claim 23, wherein said conduction foil is essentially free of perforations.

25. Operator sensing circuit as defined in claim 23, wherein said conductive foil is formed to a tube.

26. Operator sensing circuit as defined in claim 25, wherein said conductive foil has the form of a strip with opposed lateral edges forming said opposed edges of said first electrode when formed to said tube.

27. Operator sensing circuit as defined in claim 20 wherein said second electrode is formed by a handle gripping portion.

28. Operator sensing circuit as defined in claim 20 wherein said first and second electrodes together with said inner dielectric member therebetween establish a first capacity and said first electrode with said gripping surface and

said outer dielectric member therebetween establish a second capacity which in a hands-on state is in series with a third capacity formed by the human body and which together with said third capacity is arranged in parallel to said first capacity.

29. Operator sensing circuit as defined in claim 28, wherein said second capacity is greater than said first capacity.

30. Operator sensing circuit as defined in claim 1 wherein said charge sensor is provided with a receiving capacitor and wherein in a charge detection cycle said charge sensor performs a plurality of charge/discharge cycles within each of which the capacity in the element to be detected is charged and thereafter discharged into a receiving capacitor until said receiving capacitor is charged to a predefined level.

31. A method for operating an operator sensor circuit for a hand-grip of a device, comprising the following steps:

detecting a capacity of at least one capacitive sensing element incorporated in said hand-grip,

generating a capacity signal value representing said detected capacity,

comparing said capacity signal value with a hands-on threshold value in order to distinguish between a proper hands-on state which is present of the capacity signal value is below said hands-on threshold or a non-proper hands-on state, which is present if the capacity signal value is above said hands-on threshold.

32. A method as defined in claim 31, wherein when detecting the proper hands-on state full operation of said device is enabled.

33. A method as defined in claim 31, wherein when determining the presence of the non-proper hands-on state full operation of said device is disabled.

34. A method as defined in claim 31, wherein when determining the presence of the non-proper hands-on state operation of said device is reduced to a safe operational state.

35. A method as defined in claim 31, wherein in a range of predefined operational values indicating proper operative conditions of said sensing element is stored and wherein said capacity signal value is compared with said range of predefined signal values in order to determine the presence of proper operative sensor conditions of said sensing element if said capacity signal value is within said range.

36. A method as defined in claim 35, wherein said range of predefined signal values extends from a preselected stored uppermost limit value above said preselected hands-on threshold value and to a preselected stored lowermost limit value.

37. A method as defined in claim 35, wherein when determining the presence of proper operative sensor conditions full operation of said device is enabled.

38. A method as defined in claim 35, wherein when not determining the presence of proper operative sensor conditions full operation of said device is disabled.

39. A method as defined in claim 35, wherein when not determining proper operative sensor conditions operation of said device is reduced to a safe operational state.

40. A method as defined in claim 31, wherein a capacity of a capacitive reference simulator element is detected and a reference signal value indicative of said capacity is generated and wherein said reference signal value is compared with a preselected stored reference range in order to determine proper operative circuit conditions of said sensing circuit if said reference signal value is within said reference range.

41. A method as defined in claim 39, wherein when determining the presence of proper operative circuit conditions full operation of said device is enabled.

42. A method as defined in claim 39, wherein when not determining the presence of proper operative circuit conditions full operation of said device is disabled.

43. A method as defined in claim 39, wherein said controller when not determining the presence of proper operative circuit conditions reduces operation of said device to a safe operational state.

44. In an operator-sensing circuit having a charge-transfer sensor that sends a sensor charge signal to a capacitive sensing element and outputs a signal for disabling the motor of a unit of power equipment upon the absence of an operator'"'"'s hand on a hand-gripping surface of the equipment, the electrical characteristic comprising:

a) capacitive means for operating within a predetermined output range that includes preselected values that designate hands-off and hands-on conditions on the hand-gripping surface;

b) said range is effective to distinguish between the presence of an operator'"'"'s hand and foreign material on the gripping surface for avoiding a false hands-on signal.

45. A hand-grip for an operator sensing circuit, in particular an operator sensing circuit as defined in claim 44, wherein

said capacitive means includes operator-hand sensing electrode means having an inner dielectric material layer contiguously disposed on a metal handle portion of the power equipment, a metal conductor material layer contiguously disposed on the dielectric material, and an outer dielectric hand-grip material including said hand-gripping surface thereby producing a capacitance in a grasping operator'"'"'s hand, outer hand-grip material, and the metal conductor material layer;

said conductor layer includes metal foil wrapper around said inner dielectric material.

46. The hand-grip as defined in claim 45, wherein said metal conductor material comprises copper and the foil layer has a thickness of about 0.10 mm to about 0.15 mm.

47. The hand-grip as defined in claim 46, wherein said inner dielectric material layer has the structural configuration of a tube that extends along the length of the metal handle portion;

said metal foil has the structural configuration of a tube having a longitudinal axis and that extends along a delimited length of the inner dielectric material tube, and has opposed end edges that are each disposed in respective planes that traverse the longitudinal axis of the metal foil tube; and

said outer hand-grip material has a length sufficient to overlap the opposed end edges of the metal foil tube.

48. The hand-grip as defined in claim 47, wherein:

said metal foil tube has a length of from about 50 mm to about 60 mm, the opposed end edges are disposed about 30 mm from the ends of the hand-grip material, and the opposed respective transverse planes are perpendicular to the longitudinal axis of the foil tube.

49. A hand-grip for use with an operator sensing circuit comprising:

at least one capacitive sensing element incorporated in said hand-grip, having a capacity which is increased in a hands-on state of an operator'"'"'s hand on said hand-grip when compared with a hands-off state of said hand-grip, said capacitive sensing element comprising a first electrode arranged on an inner dielectric member said inner dielectric member being disposed on a second electrode and said first electrode being covered by an outer dielectric member.

50. Hand-grip as defined in claim 49, wherein said first electrode has tube-like structural configuration.

51. Hand-grip as defined in claim 50, wherein said tube-like structural configuration extends between opposed edges in direction of its axis with an extension which is smaller than the extension of an operator'"'"'s hand in this direction when gripping said hand-grip.

52. Hand-grip as defined in claim 49 wherein said first electrode comprises a conductive foil.

53. Hand-grip as defined in claim 52, wherein said conduction foil is essentially free of perforations.

54. Hand-grip as defined in claim 52, wherein said conductive foil is formed to a tube.

55. Hand-grip as defined in claim 54, wherein said conductive foil has the form of a strip with opposed lateral edges forming said opposed edges, of said first electrode when formed to said tube.

56. Hand-grip as defined in claim 49, wherein said second electrode is formed by a handle gripping portion.

57. Hand-grip as defined in claim 49, wherein said first and second electrodes together with said inner dielectric member therebetween establish a first capacity and said first electrode with said gripping surface and said outer dielectric member therebetween establish a second capacity which in a hands-on state is in series with a third capacity formed by the human body and which together with said third capacity is arranged in parallel to said first capacity.

58. Hand-grip as defined in claim 57, wherein said second capacity is greater than said first capacity.

59. In an operator-sensing circuit having a charge-transfer sensor that sends a sensor charge signal to a capacitive sensing element and in response outputs a signal for disabling the motor of a unit of power equipment upon the absence of an operator'"'"'s hand on a hand-gripping surface of the equipment, the combination comprising:

a) multiplexing means and capacitive means including operator-hand sensing element and reference simulator element receiving said sensor charge signal from the multiplexing means;

b) said simulator element being effective to send a reference signal having a designated standard value for determining a defect in the operator-sensing system;

c) microcontroller means electrically coupled to said multiplexing means including a series of switches for issuing switching signals to alternately turn said series of switches on and off to sequentially send said sensor charge signal to each sensing element and reference simulator element.

d) said microcontroller means electrically coupled for issuing command signals to said charge-transfer sensor to send said charge signal to the multiplexing means for distribution to said sensing and reference element;

e) said charge-transfer sensor being effective to send a raw data output signal corresponding to each said respective element charge to said microcontroller means for processing; and

f) said microcontroller means being effective to disable said engine upon determining that the reference charge signals does not conform to said designated standard value, and upon alternatively determining that the sensing element charge signal indicates the absence of the operator'"'"'s hand from the hand-gripping surface.

60. A method of sensing the presence of an operator'"'"'s hand on a gripping surface of a power equipment unit and causing cessation of operation of a component system of the equipment if the operator'"'"'s hand is removed from the gripping surface, the steps of the method comprising:

a) providing a sensing element affixed to said gripping surface that includes a capacitive means operating within a predetermined capacitor charge range including preselected values that designate hands-off and hands-on conditions on the hand-gripping surface;

b) said capacitor charge range is effective to distinguish between the presence of an operator'"'"'s hand and foreign material on said gripping surface for avoiding a false hands-on signal;

c) said capacitor charge range includes a hands-off section in which foreign materials add capacitance to the hand-gripping surface that may produce a false hands-on condition, and a true hands-on section in which the operator'"'"'s hand is grasping the hand-gripping surface and provides an accurate capacitor charge value that allows the power equipment continued operation;

d) providing a charge-transfer sensor electrically coupled to the sensing electrode;

e) providing microcontroller means electrically coupled to the charge-transfer sensor for periodically commanding the sensor to transfer charge to the sensing element that senses the quantity of charge on the sensing element and generates a raw data output signal to the microcontroller means when the quantity of charge on the sensing electrode is sensed;

f) processing the raw data output signal in said microcontroller means to determine if the quantity of charge on the sensing element is in said true hands-on section of the capacitor range;

g) said microcontroller means is electrically coupled to said component system of the equipment and causes cessation of operation of the component system when the raw data output signal of the charge-transfer sensor indicates that the quantity of charge is not within the true hands-on section of said capacitor discharge range.

61. A capacitive operator-sensing circuit in combination with a mobile power equipment unit, the combination comprising:

a) the mobile power equipment including an internal combustion engine, a magneto of the engine'"'"'s ignition system, and a hand-gripping surface for an operator to grip and control movement of the mobile power equipment unit;

b) the capacitive operator-sensing circuit being adapted to sense the presence of an operator'"'"'s hand on the gripping surface to shut off the engine if the operator'"'"'s hand is absent from the gripping surface;

c) the capacitive operator-sensing circuit including at least one sensing element affixed to said gripping surface that includes capacitive means for operating within a predetermined charge range that includes preselected standard values that designate hands-off and hands-on conditions on the hand-gripping surface;

d) said charge range including a hands-off section in which foreign materials add capacitance of the hand-gripping surface that may produce a false hands-on condition, and a true hands-on section which indicates that the operator'"'"'s hand is grasping the hand-gripping surface;

e) said sensing element is electrically coupled to charge-transfer sensor means for sensing any quantity of charge on the electrode means;

f) said charge-transfer sensor means is electrically coupled to the microcontroller means for periodically commanding the charge transfer sensor means to transfer charge to the sensing element, and to sense the quantity of charge on the sensing element;

g) said charge transfer sensor means being effective to generate raw data output signals for the microcontroller means to process when the quantity of charge on the sensing element is sensed;

h) said microcontroller means being effective to process a raw data output signal for determining if a corresponding quantity of charge on the sensing element is in said true hands-on section of the capacitor range,

i) said microcontroller means being electrically coupled to said magneto of the ignition system for causing cessation of the engine when the raw data output signal of the charge-transfer sensor means indicates that the sensed quantity of charge is not within the true hands-on section of said charge range.