ELECTRONIC DEVICE, ELECTROSTATIC CAPACITANCE SENSOR AND TOUCH PANEL

• US 20150286335A1
• Filed: 10/11/2013
• Published: 10/08/2015
• Est. Priority Date: 10/12/2012
• Status: Active Grant

• Current Assignee: Tianma Microelectronics Company Limited
• Original Assignee: NLT Technologies, Ltd. (Tianma Microelectronics Company Limited)
• Inventors: Haga, Hiroshi, Asada, Hideki, Sugimoto, Daisuke
• Granted Patent: US 9,529,473 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06F 3/04166 Details of scanning methods, e.g. sampling time, grouping of sub areas or time sharing with display driving Synchronisation with the driving of the display or the backlighting unit to avoid interferences generated internally G06F3/04184
• CPC Class Codes: G06F 3/0418 for error correction or compensation, e.g. based on parallax, calibration or alignment
• CPC Class Codes: G06F 3/04182 Filtering of noise external to the device and not generated by digitiser components
• CPC Class Codes: G06F 3/044 by capacitive means
• CPC Class Codes: G06F 3/0444 using a single conductive element covering the whole sensing surface, e.g. by sensing the electrical current flowing at the corners
• CPC Class Codes: H03K 17/962 Capacitive touch switches
• CPC Class Codes: H03K 2217/960705 Safety of capacitive touch and proximity switches, e.g. increasing reliability, fail-safe

Abstract

When an excitation frequency of a touch panel is coincident with or in the vicinity of a frequency of external noise, noise cannot be removed by a bandpass filter. Also when a touch detecting operation period is limited to a short period of time such as a non-address period, frequency resolution is reduced and a noise removal effect of averaging is reduced, so that an S/N ratio is decreased. The electronic apparatus of the present invention includes a sensor system 101, an excitation generating unit 102 which generates an intermittent sine wave signal and applies the same to the sensor system, and a demodulation unit 105 which demodulates an amplitude modulated signal which is an output of the sensor system, in which the demodulation unit generates a demodulated signal D(t) using both a response x1(t) of the sensor system in a period when the excitation generating unit outputs a sine wave and a response z1(t) of the sensor system in a period, at least either immediately before or immediately after the above-mentioned period, when the excitation generating unit does not output a sine wave.

Claims

1-11. -11. (canceled)

12. An electronic apparatus comprising:

a sensor system;

an excitation generating unit which generates an intermittent sine wave signal and applies the intermittent sine wave signal to the sensor system; and

a demodulating unit which demodulates an amplitude modulated signal which is an output of the sensor system,

wherein the demodulating unit generates a demodulated signal using both a response of the sensor system in a period when the excitation generating unit outputs a sine wave and a response of the sensor system in a period, at least either immediately before or immediately after the aforementioned period, when the excitation generating unit does not output a sine wave, and

wherein with a vector as X, which is obtained from an amplitude and a phase, the amplitude and the phase being calculated from the response of the sensor system in a period in which the excitation generating unit has output the sine wave, by extracting a frequency component of the sine wave from the response of the sensor system, and with vectors as Y and Z, which are obtained from an amplitude and a phase, the amplitude and the phase being respectively calculated from the response of the sensor system in periods, immediately before and immediately after the aforementioned period, when the excitation generating unit does not output the sine wave, by extracting a frequency component of the sine wave from the response of the sensor system, the demodulated signal corresponds to a constant multiplication of |X−

k·

M| in which M represents a mean vector of Y and Z, and k represents a coefficient whose value is determined using a response of the sensor system in a period when the excitation generating unit does not output the sine wave.

13. An electrostatic capacitance sensor including the electronic apparatus according to claim 12, comprising:

a resistive sheet; and

a sensor system including a driving and detecting circuit connected to the resistive sheet for applying a voltage to the resistive sheet to measure and output current flowing through the resistive sheet,

wherein a touching state or coordinates of an indicator are detected by detecting an electrostatic capacitance of a capacitor formed by the resistive sheet and the indicator.

14. An electrostatic capacitance sensor including the electronic apparatus according to claim 12, comprising:

an electrode; and

a sensor system including a driving and detecting circuit connected to the electrode for applying a voltage to the electrode to measure and output current flowing through the electrode,

wherein a touching state or coordinates of an indicator are detected by detecting an electrostatic capacitance of a capacitor formed by the electrode and the indicator.

15. An electrostatic capacitance sensor including the electronic apparatus according to claim 12, comprising:

a first electrode;

a second electrode; and

a sensor system including a driving circuit which applies a voltage to the first electrode and a detecting circuit which measures and outputs current flowing through the second electrode,

wherein a touching state or coordinates of an indicator are detected by detecting an electrostatic capacitance of a capacitor formed by the first electrode and the second electrode.

16. The electrostatic capacitance sensor according to claim 13, comprising a display device,

wherein a non-address period of the display device has a period when the excitation generating unit outputs a sine wave and a period when the unit does not output a sine wave, and

wherein the demodulated signal is generated using both a response of the sensor system in the period when a sine wave is output and a response of the sensor system in the period when the sine wave is not output.

17. The electrostatic capacitance sensor according to claim 14, comprising a display device,

wherein a non-address period of the display device has a period when the excitation generating unit outputs a sine wave and a period when the unit does not output a sine wave, and

wherein the demodulated signal is generated using both a response of the sensor system in the period when a sine wave is output and a response of the sensor system in the period when the sine wave is not output.

18. The electrostatic capacitance sensor according to claim 15, comprising a display device,

wherein a non-address period of the display device has a period when the excitation generating unit outputs a sine wave and a period when the unit does not output a sine wave, and

wherein the demodulated signal is generated using both a response of the sensor system in the period when a sine wave is output and a response of the sensor system in the period when the sine wave is not output.

19. The electrostatic capacitance sensor according to claim 13, wherein a value of the coefficient k is determined using both amplitudes:

an amplitude of a forward noise as a noise obtained at the time of non-output of a sine wave before the excitation generating unit outputs a sine wave; and

an amplitude of a backward noise as a noise obtained at the time of non-output of a sine wave after the excitation generating unit outputs a sine wave.

20. The electrostatic capacitance sensor according to claim 14, wherein a value of the coefficient k is determined using both amplitudes:

an amplitude of a forward noise as a noise obtained at the time of non-output of a sine wave before the excitation generating unit outputs a sine wave; and

an amplitude of a backward noise as a noise obtained at the time of non-output of a sine wave after the excitation generating unit outputs a sine wave.

21. The electrostatic capacitance sensor according to claim 15 wherein a value of the coefficient k is determined using both amplitudes:

an amplitude of a forward noise as a noise obtained at the time of non-output of a sine wave before the excitation generating unit outputs a sine wave; and

an amplitude of a backward noise as a noise obtained at the time of non-output of a sine wave after the excitation generating unit outputs a sine wave.

22. A touch panel including the electronic apparatus according to claim 12, comprising:

a resistive sheet; and

a sensor system including a driving and detecting circuit connected to the resistive sheet for applying a voltage to the resistive sheet to measure and output current flowing through the resistive sheet,

wherein a touching state or coordinates of an indicator are detected by detecting an electrostatic capacitance of a capacitor formed by the resistive sheet and the indicator.

23. A touch panel including the electronic apparatus according to claim 12, comprising:

an electrode; and

a sensor system including a driving and detecting circuit connected to the electrode for applying a voltage to the electrode to measure and output current flowing through the electrode,

wherein a touching state or coordinates of an indicator are detected by detecting an electrostatic capacitance of a capacitor formed by the electrode and the indicator.

24. A touch panel including the electronic apparatus according to claim 12, comprising:

a first electrode;

a second electrode; and

a sensor system including a driving circuit which applies a voltage to the first electrode and a detecting circuit which measures and outputs current flowing through the second electrode,

wherein a touching state or coordinates of an indicator are detected by detecting an electrostatic capacitance of a capacitor formed by the first electrode and the second electrode.

25. The electronic apparatus according to claim 12, comprising a display device, wherein

a non-address period of the display device has a period when the excitation generating unit outputs a sine wave and a period when the unit does not output a sine wave, and

a demodulated signal is generated using both a response of the sensor system in the period when the sine wave is output and a response of the sensor system in the period when the sine wave is not output.

26. The touch panel according to claim 22, comprising a display device, wherein

a non-address period of the display device has a period when the excitation generating unit outputs a sine wave and a period when the unit does not output a sine wave, and

a demodulated signal is generated using both a response of the sensor system in the period when the sine wave is output and a response of the sensor system in the period when the sine wave is not output.

27. The touch panel according to claim 23, comprising a display device, wherein

a non-address period of the display device has a period when the excitation generating unit outputs a sine wave and a period when the unit does not output a sine wave, and

a demodulated signal is generated using both a response of the sensor system in the period when the sine wave is output and a response of the sensor system in the period when the sine wave is not output.

28. The touch panel according to claim 24, comprising a display device, wherein

a non-address period of the display device has a period when the excitation generating unit outputs a sine wave and a period when the unit does not output a sine wave, and

a demodulated signal is generated using both a response of the sensor system in the period when the sine wave is output and a response of the sensor system in the period when the sine wave is not output.