Self-checking circuit, touch sensing device, and electronic device

Patent metadata

Field	Value
Publication number	US-11275465-B2
Application number	US-202017060554-A
Country	US
Kind code	B2
Filing date	Oct 1, 2020
Priority date	Feb 6, 2020
Publication date	Mar 15, 2022
Grant date	Mar 15, 2022

Abstract

A self-checking circuit includes: an edge detector configured to output an edge detection signal having a pulse generated during detection of an edge of a pulse signal having a pulse train; a charging and discharging circuit configured to perform a charging operation and a discharging operation based on the edge detection signal to generate a detection voltage; and a comparison circuit configured to check whether the pulse signal is normal, based on the detection voltage, to output a checking signal.

First claim

What is claimed is:

1. A self-checking circuit, comprising:
an edge detector configured to output an edge detection signal having a pulse generated during detection of an edge of a pulse signal having a pulse train;
a charging and discharging circuit configured to perform a charging operation and a discharging operation based on the edge detection signal to generate a detection voltage; and
a comparison circuit configured to check whether the pulse signal is normal, based on the detection voltage, to output a checking signal.

2. The self-checking circuit of claim 1 , wherein a pulse width of the pulse is shorter than a pulse width of the pulse signal.

3. The self-checking circuit of claim 1 , wherein the charging and discharging circuit comprises:
a switch connected between a power supply voltage terminal and a ground;
a capacitor connected between the switch and the ground, and configured to perform the charging operation when the switch is in an ON state; and
a resistor connected between a connection node of the switch and the capacitor and the ground, and configured to provide a discharging path between the capacitor and the ground when the switch is in an OFF state.

4. The self-checking circuit of claim 1 , wherein the comparison circuit comprises:
a window comparison circuit configured to compare the detection voltage with a first reference voltage and a second reference voltage to output the checking signal to have a high level when the detection voltage is higher than the first reference voltage and a low level when the detection voltage is lower than the second reference voltage; and
an output selector configured to perform a logical AND operation on an enable signal and the checking signal.

5. The self-checking circuit of claim 1 , wherein the charging and discharging circuit comprises:
a first current source connected between a power supply voltage terminal and a ground;
a second current source connected between the first current source and the ground, and configured to be turned off when the first current source is turned on and turned on when the first current source is turned off; and
a capacitor connected between an intermediate connection node between the first current source and the second current source and the ground, and configured to provide the detection voltage by performing a charging operation when the first current source is turned on and performing a discharging operation when the second current source is turned on.

6. A touch sensing device for an electronic device including a touch switching unit, the touch sensing device comprising:
a sensing inductor disposed inside of a touch member disposed in a housing;
a sensing capacitor electrically connected to the sensing inductor;
an oscillation circuit including the sensing inductor and the sensing capacitor, and configured to generate an oscillation signal having a frequency varying depending on a touch input, including a touch-contact or touch-force, through the touch switching unit;
a reference signal generation circuit configured to generate a reference signal corresponding to a reference clock;
a signal processor configured to receive the reference signal from the reference signal generation circuit and detect whether a touch input has occurred, using the oscillation signal and the reference signal, to output a touch detection signal; and
a self-checking circuit configured to check whether either one or both of the oscillation signal and the reference signal is normal, and provide a checking signal.

7. The touch sensing device of claim 6 , wherein the self-checking circuit comprises:
a first checking circuit configured to check whether the oscillation signal is normal and provide a first checking signal; and
a second checking circuit configured to check whether the reference signal is normal and provide a second checking signal.

8. The touch sensing device of claim 7 , wherein the first checking circuit comprises:
a first edge detector configured to output a first edge detection signal having a pulse generated during detection of an edge of the oscillation signal;
a first charging and discharging circuit configured to perform a charging operation and a discharging operation based on the first edge detection signal to generate a first detection voltage; and
a first comparison circuit configured to check whether the oscillation signal is normal, based on the first detection voltage, to output a first checking signal.

9. The touch sensing device of claim 8 , wherein the first comparison circuit comprises:
a window comparison circuit configured to compare the first detection voltage with a first reference voltage and a second reference voltage to output the first checking signal to have a high level when the first detection voltage is higher than the first reference voltage and a low level when the first detection voltage is lower than the second reference voltage; and
an output selector configured to perform a logical AND operation on an enable signal and the first checking signal.

10. The touch sensing device of claim 8 , wherein the first charging and discharging circuit comprises:
a first current source connected between a power supply voltage terminal and a ground;
a second current source connected between the first current source and the ground to be turned off when the first current source is turned on and be turned on when the first current source is turned off; and
a capacitor connected between an intermediate connection node between the first current source and the second current source and the ground to provide the first detection voltage by performing the charging operation when the first current source is turned on and performing the discharging operation when the second current source is turned on.

11. The touch sensing device of claim 8 , wherein the second checking circuit comprises:
a second edge detector configured to output a second edge detection signal having a pulse generated during detection of an edge of the reference signal;
a second charging and discharging circuit configured to perform a charging operation and a discharging operation based on the second edge detection signal to generate a second detection voltage; and
a second comparison circuit configured to check whether the reference signal is normal, based on the second detection voltage, to output a second checking signal.

12. The touch sensing device of claim 11 , wherein a pulse width of the pulse generated during the detection of the edge of the oscillation signal is shorter than a pulse width of the oscillation signal, and
a pulse width of the pulse generated during the detection of the edge of the reference signal is shorter than a pulse with of the reference signal.

13. The touch sensing device of claim 11 , wherein each of the first and second charging and discharging circuits comprises:
a switch connected between a power supply voltage terminal and a ground;
a capacitor connected between the switch and the ground to perform a charging operation when the switch enters an ON state; and
a resistor connected between a connection node of the switch and the capacitor and the ground to provide a discharging path between the capacitor and the ground when the switch enters an OFF state.

14. The touch sensing device of claim 11 , wherein the second comparison circuit comprises:
a window comparison circuit configured to compare the second detection voltage with a first reference voltage and a second reference voltage to output the second checking signal to have a high level when the second detection voltage is higher than the first refe

Assignees

• Samsung Electro Mech

Inventors

• Park Jung Eui
• Ko Joo Yul

Classifications

• G06F3/044 Primary

  by capacitive means · CPC title

• G01R19/16576

  comparing DC or AC voltage with one threshold (G01R19/16514, G01R19/16519, G01R19/16528, G01R19/16533 and G01R19/1659 take precedence) · CPC title

• G01R31/2829

  Testing of circuits in sensor or actuator systems (testing of apparatus for measuring electric or magnetic variables G01R35/00; testing of indicating or recording apparatus G01D; in airbag systems B60R21/0173; checking gas analysers G01N33/007; monitoring or fail-safe circuits for electromagnets H01F7/1844) · CPC title

• G06F3/0416 Primary

  Control or interface arrangements specially adapted for digitisers · CPC title

• G06F3/04182

  Filtering of noise external to the device and not generated by digitiser components · CPC title