TWI792766B - Self-capacitance sensing circuit, capacitive touch chip, capacitive touch display device and information processing device - Google Patents

Abstract

A self-capacitance sensing circuit has a switchable capacitance feedback amplifier circuit, the switchable capacitance feedback amplifier circuit has an input terminal, a sensing terminal and an output terminal, and the input terminal is used to couple a source The driving line and an excitation pulse signal, the sensing end is used to couple a sensing electrode, and the output end is used to provide an output voltage, characterized in that: the switching capacitance feedback amplifier circuit Sequentially perform a first reset operation and a first integration operation during the period from a low potential to a high potential, and sequentially perform a second reset operation during the period when the excitation pulse signal changes from the high potential to the low potential and a second integration operation; during the first integration operation, one of the amplifiers of the switched capacitive feedback amplifier circuit has a first offset voltage so that the output voltage presents a first level, during the second During the integration operation, the amplifier has a second offset voltage to make the output voltage exhibit a second level, the second offset voltage is the reverse equivalent voltage of the first offset voltage; and the switching A subtraction operation circuit of the capacitive feedback amplifier circuit generates a sensing voltage according to the difference between the second level and the first level.

Description

Self-capacitance sensing circuit, capacitive touch chip, capacitive touch display device and information processing device

The present invention relates to a self-capacitance detection circuit, in particular to a self-capacitance sensing circuit capable of compensating basic capacitance.

Common self-capacitive touch chips use capacitive amplifiers or charge-to-voltage circuits to detect touch operations on a capacitive touch screen.

However, because the basic capacitance of the capacitive touch screen is generally much larger than the feedback capacitance on the capacitor amplifier, the output voltage of the capacitor amplifier is saturated. Therefore, the existing capacitor amplifier will set a compensation capacitor equivalent to the basic capacitance at the input end. to avoid output voltage saturation.

However, the compensation capacitor occupies a relatively large chip area, which greatly increases the cost of the chip.

In order to solve the above problems, there is an urgent need in the art for a novel self-capacitance detection circuit to avoid compensation capacitors.

The main purpose of the present invention is to disclose a self-capacitance sensing circuit, which can prevent the output voltage of the internal amplifier from being saturated by changing the input offset voltage of its internal amplifier during the sensing operation of a sensing capacitance .

Another object of the present invention is to disclose a capacitive touch chip, which can use the self-capacitance sensing circuit above, so that the capacitive touch chip can avoid the internal amplifier without increasing the compensation capacitance of a large area. Output saturation due to the base capacitance of a capacitive touch screen.

Another object of the present invention is to disclose a capacitive touch display device, which can meet the touch driving requirements of touch screens with different capacitive specifications through the above-mentioned capacitive touch chip.

Another object of the present invention is to disclose an information processing device, which can easily meet various touch requirements by using the above-mentioned capacitive touch chip with touch screens with different capacitance specifications.

In order to achieve the aforementioned purpose, a self-capacitance sensing circuit is proposed, which has a switchable capacitance feedback amplifier circuit, the switchable capacitance feedback amplifier circuit has an input terminal, a sensing terminal and an output terminal, the input The terminal is used to couple a source driving line and an excitation pulse signal, the sensing terminal is used to couple a sensing electrode, and the output terminal is used to provide an output voltage, and is characterized in that:

The switched capacitive feedback amplifier circuit sequentially executes a first reset operation and a first integration operation during the period when the excitation pulse signal changes from a low potential to a high potential, and when the excitation pulse signal changes from the high potential to the Perform a second reset operation and a second integration operation in sequence during the period of low potential;

During the first integration operation, an amplifier of the switched capacitive feedback amplifier circuit has a first offset voltage so that the output voltage exhibits a first level, and during the second integration operation, the amplifier is enabled having a second offset voltage to cause the output voltage to exhibit a second level, the second offset voltage being an inverse equivalent voltage of the first offset voltage; and

A subtraction operation circuit of the switched capacitive feedback amplifier circuit generates a sensing voltage according to the difference between the second level and the first level.

In one embodiment, the amplifier has at least one active load with programmable channel width to set the first offset voltage and the second offset voltage.

In one embodiment, the active load with programmable channel width includes a group of multiple transistors that can be connected in parallel.

In one embodiment, the plurality of transistor systems that can be connected in parallel form an equivalent transistor under the control of a plurality of digital signals.

In one embodiment, the amplifier is a rail-to-rail amplifier.

To achieve the aforementioned purpose, the present invention further proposes a capacitive touch chip, which is used to couple a capacitive touch display to detect at least one touch operation on the capacitive touch display, and its characteristics It has the self-capacitance sensing circuit as mentioned above.

To achieve the aforementioned purpose, the present invention further proposes a capacitive touch display device, which has a capacitive touch chip and a capacitive touch display, and the capacitive touch chip is used to couple the capacitive touch The display screen is used to detect at least one touch operation on the capacitive touch display screen, and it is characterized in that the capacitive touch chip has a self-capacitance sensing circuit as described above.

In one embodiment, the capacitive touch display screen has a display module, and the display module can be a liquid crystal display module, a micro light emitting diode display module, a mini light emitting diode display module group, a quantum dot light emitting diode display module or an organic light emitting diode display module.

To achieve the aforementioned purpose, the present invention further proposes an information processing device, which has a central processing unit and a capacitive touch display device, wherein the central processing unit is used to communicate with the capacitive touch display device, and the capacitor The touch display device has a capacitive touch chip and a capacitive touch display, and the capacitive touch chip is used to couple the capacitive touch display to detect the capacitive touch display. At least one touch operation, and it is characterized in that the capacitive touch chip has the self-capacitance sensing circuit as mentioned above.

In one embodiment, the capacitive touch display screen has a display module, and the display module can be a liquid crystal display module, a micro light emitting diode display module, a mini light emitting diode display module group, a quantum dot light emitting diode display module or an organic light emitting diode display module.

In a possible embodiment, the information processing device may be a smart phone, a portable computer, a vehicle computer, a wearable electronic device or an access control device.

In order to enable your review committee members to further understand the structure, features and purpose of the present invention, drawings and detailed descriptions of preferred specific embodiments are hereby attached.

Please refer to FIG. 1 , which is a circuit diagram of an embodiment of the self-capacitance sensing circuit of the present invention. As shown in Figure 1, a self-capacitance sensing circuit 100 has a switchable capacitance feedback amplifier circuit 110 and a subtraction operation circuit 120, wherein the switchable capacitance feedback amplifier circuit 110 has an input terminal A and a sensing terminal B and an output terminal C, the input terminal A is used to couple a source drive line 11 and an excitation pulse signal V _STIM , the sensing terminal B is used to couple a sensing electrode 10, and the output terminal C is used to provide an output voltage V _OUT .

The switched capacitive feedback amplifying circuit 110 has an amplifier 111 , a feedback capacitor 112 , a first switch 113 a , a second switch 113 b , a third switch 113 c and a control circuit 114 .

The amplifier 111 has a positive input terminal, a negative input terminal, an output terminal and a plurality of offset voltage control terminals, wherein the positive input terminal is coupled to the input terminal A, and the negative input terminal is connected via the second switch 113b The control is coupled to the sensing terminal B, the output terminal is coupled to the output terminal C, and the plurality of offset voltage control terminals are coupled to a plurality of control signals CNTL. In addition, the amplifier 111 has at least one active load with a programmable channel width to change its input offset voltage, wherein the active load with a programmable channel width may include a group of multiple transistors that can be connected in parallel, and the group can be The plurality of transistor systems connected in parallel form an equivalent transistor according to the control of the plurality of control signals CNTL. In addition, preferably, the amplifier 111 is a rail-to-rail amplifier.

The feedback capacitor 112 is connected in parallel with the first switch 113a between the negative input terminal and the output terminal of the amplifier 111; the second switch 113b is coupled between the negative input terminal and the sensing terminal B; and The three switches 113c are coupled between the input terminal A and the sensing terminal B. In addition, the first switch 113a, the second switch 113b, and the third switch 113c are correspondingly controlled by a first switch signal S1, a second switch signal S2, and a third switch signal S3 to turn on or turn off their respective channels. .

The control circuit 114 is used to generate the excitation pulse signal V _STIM , the first switch signal S1 , the second switch signal S2 , the third switch signal S3 and the plurality of control signals CNTL, and execute A self-capacitance sensing operation, the self-capacitance sensing operation includes: (1) changing the first switch signal S1, _the second switch signal S2 and The state of the third switch signal S3 is to perform a first reset operation and a first integration operation in sequence, and change the first switch signal S1 during the period when the excitation pulse signal V _STIM changes from the high potential to the low potential , the state of the second switch signal S2 and the third switch signal S3 to perform a second reset operation and a second integration operation in sequence; (2) make the amplifier 111 have a first integration operation during the first integration operation an offset voltage so that the output voltage V _OUT presents a first level, during the second integration operation, the amplifier 111 has a second offset voltage so that the output voltage V _OUT presents a second level, the second offset voltage is the reverse equivalent voltage of the first offset voltage; and

(3) Driving the subtraction circuit 120 to generate a sensing voltage V _SENSE according to the difference between the second level and the first level of the output voltage V _OUT , wherein the subtraction circuit 120 can be a digital circuit or an analog circuit.

In detail, during the first reset operation, the states of the first switch signal S1, the second switch signal S2 and the third switch signal S3 present a combination of (active, inactive, active), And the amplifier 111 works with an initial offset voltage close to 0; during the first integration operation, the states of the first switch signal S1, the second switch signal S2 and the third switch signal S3 are present a combination of (inactive, active, inactive), and change the input offset voltage of the amplifier 111 to the first offset voltage; during the second reset operation, the first switch signal S1, the The state of the second switch signal S2 and the third switch signal S3 is a combination of (active, inactive, active), and the input offset voltage of the amplifier 111 is changed to the initial offset voltage close to 0; During the second integration operation, the states of the first switch signal S1, the second switch signal S2 and the third switch signal S3 present a combination of (non-active, active, non-active), and the amplifier 111 The input offset voltage is changed to the second offset voltage.

The principle of the present invention is: (1) the sensing electrode 10 itself has a basic capacitance C1, and there is a parasitic capacitance C2 between it and the source driving line 11; (2) the excitation pulse signal V _STIM is coupled to the source The pole driving line 11 is used to virtually eliminate the parasitic capacitance C2; and (3) utilize the first offset voltage and the second offset voltage to prevent the output voltage V _OUT of the amplifier 111 from being saturated (that is, maintain in the linear working region), and by making the first offset voltage and the second offset voltage inversely equivalent to make the sensing voltage V _SENSE when no touch event occurs on the sensing electrode 10 The level is equal to 0 (ie no response). Please refer to FIG. 2 , which shows a sensing waveform diagram of a no-touch event of the self-capacitance sensing circuit 100 . As shown in FIG. 2 , the level of the output voltage V _OUT at point A (about 3V) is the same as that at point B (about 3V), so that the level of the sensing voltage V _SENSE is equal to 0.

According to the above description, the self-capacitance sensing circuit 100 of the present invention can be applied in a capacitive touch chip to compensate the output saturation of the capacitive amplifier caused by the basic capacitance of a capacitive touch display. Please refer to FIG. 3 , which shows a block diagram of an embodiment of the capacitive touch display device of the present invention. As shown in FIG. 3 , a capacitive touch display device 200 has a capacitive touch chip 210 and a capacitive touch display 220, wherein the capacitive touch chip 210 is coupled to the capacitive touch display 220 for At least one touch operation on the capacitive touch display screen 220 is detected, and it has at least one self-capacitance sensing circuit 100 . In addition, the capacitive touch display screen 220 has a display module, and the display module can be a liquid crystal display module, a micro light emitting diode display module, a mini light emitting diode display module, a quantum A dot light emitting diode display module or an organic light emitting diode display module.

According to the above description, the present invention further provides an information processing device. Please refer to FIG. 4 , which shows a block diagram of an embodiment of an information processing device of the present invention. As shown in FIG. 4, an information processing device 300 has a central processing unit 310 and a capacitive touch display device 320, wherein the capacitive touch display device 320 is realized by the capacitive touch display device 200, and the central processing unit 310 The unit 310 is used for communicating with the capacitive touch display device 320 . In addition, the information processing device 300 can be a smart phone, a portable computer, a vehicle computer, a wearable electronic device or an access control device.

With the design disclosed above, the present invention has the following advantages:

1. The self-capacitance sensing circuit of the present invention can prevent the output voltage of the internal amplifier from being saturated by changing the input offset voltage of the internal amplifier during the sensing operation of a sensing capacitance.

2. The capacitive touch chip of the present invention can use the above-mentioned self-capacitance sensing circuit, so that the capacitive touch chip can prevent the internal amplifier from being affected by a capacitive touch without increasing the compensation capacitance of a large area. The basic capacitance of the display screen causes the output to saturate.

3. The capacitive touch display device of the present invention can meet the touch driving requirements of touch screens with different capacitive specifications by using the above-mentioned capacitive touch chip.

4. The information processing device of the present invention can use the above-mentioned capacitive touch chip to match touch screens with different capacitance specifications, so as to easily meet various touch requirements.

What is disclosed in this case is a preferred embodiment. For example, any partial changes or modifications derived from the technical ideas of this case and easily deduced by those who are familiar with the technology are within the scope of the patent right of this case.

To sum up, regardless of the purpose, means and efficacy of this case, it shows that it is very different from the conventional technology, and its first invention is practical, and it does meet the patent requirements of the invention. I implore your review committee to understand it clearly and grant a patent as soon as possible. Society is for the Most Prayer.

10: Sensing electrode 11: Source drive line 100: Self-capacitance sensing circuit 110: Switched capacitive feedback amplifier circuit 111: Amplifier 112: Feedback capacitor 113a: first switch 113b: second switch 113c: the third switch 114: control circuit 120: Subtraction operation circuit 200: capacitive touch display device 210: capacitive touch chip 220: capacitive touch screen 300: information processing device 310: central processing unit 320: capacitive touch display device

FIG. 1 is a circuit diagram of an embodiment of a self-capacitance sensing circuit of the present invention. FIG. 2 illustrates a sensing waveform diagram of a no-touch event in the self-capacitance sensing circuit of FIG. 1 . FIG. 3 is a block diagram of an embodiment of a capacitive touch display device of the present invention. FIG. 4 is a block diagram of an embodiment of an information processing device of the present invention.

10: Sensing electrode

11: Source drive line

100: Self-capacitance sensing circuit

110: Switched capacitive feedback amplifier circuit

111: Amplifier

112: Feedback capacitor

113a: first switch

113b: second switch

113c: the third switch

114: control circuit

120: Subtraction operation circuit

Claims (11)

A self-capacitance sensing circuit has a switchable capacitance feedback amplifier circuit, the switchable capacitance feedback amplifier circuit has an input terminal, a sensing terminal and an output terminal, and the input terminal is used to couple a source Drive line and an excitation pulse signal, the sensing end is used to couple a sensing electrode, and the output end is used to provide an output voltage, characterized in that: The switched capacitive feedback amplifier circuit sequentially executes a first reset operation and a first integration operation during the period when the excitation pulse signal changes from a low potential to a high potential, and when the excitation pulse signal changes from the high potential to the Perform a second reset operation and a second integration operation in sequence during the period of low potential; During the first integration operation, an amplifier of the switched capacitive feedback amplifier circuit has a first offset voltage so that the output voltage exhibits a first level, and during the second integration operation, the amplifier is enabled having a second offset voltage to cause the output voltage to exhibit a second level, the second offset voltage being an inverse equivalent voltage of the first offset voltage; and A subtraction operation circuit of the switched capacitive feedback amplifier circuit generates a sensing voltage according to the difference between the second level and the first level. The self-capacitance sensing circuit described in Claim 1 of the patent application, wherein the amplifier has at least one active load with programmable channel width to set the first offset voltage and the second offset voltage. The self-capacitance sensing circuit described in item 2 of the scope of the patent application, wherein the active load with programmable channel width includes a group of multiple transistors that can be connected in parallel. The self-capacitance sensing circuit as described in item 3 of the scope of the patent application, wherein the group of multiple transistor systems that can be connected in parallel forms an equivalent transistor according to the control of multiple digital signals. In the self-capacitance sensing circuit described in claim 1 of the patent application, the amplifier is a rail-to-rail amplifier. A capacitive touch chip, used for coupling a capacitive touch display to detect at least one touch operation on the capacitive touch display, characterized in that it has the characteristics of items 1 to 5 in the scope of the patent application The self-capacitance sensing circuit described in any one of the items. A capacitive touch display device has a capacitive touch chip and a capacitive touch display, and the capacitive touch chip is used to couple the capacitive touch display to detect the capacitive touch At least one touch operation on the display screen, and it is characterized in that the capacitive touch chip has a self-capacitance sensing circuit as described in any one of items 1 to 5 of the scope of application. The capacitive touch display device as described in item 7 of the scope of patent application, wherein the capacitive touch display has a display module, and the display module is composed of a liquid crystal display module, a micro light emitting diode A display module selected from the group consisting of a display module, a mini light emitting diode display module, a quantum dot light emitting diode display module and an organic light emitting diode display module. An information processing device, which has a central processing unit and a capacitive touch display device, wherein the central processing unit is used to communicate with the capacitive touch display device, and the capacitive touch display device has a capacitive touch display device A touch chip and a capacitive touch display, the capacitive touch chip is used to couple the capacitive touch display to detect at least one touch operation on the capacitive touch display, and its It is characterized in that the capacitive touch chip has a self-capacitance sensing circuit as described in any one of items 1 to 5 of the scope of the patent application. The information processing device as described in item 9 of the scope of the patent application, wherein the capacitive touch display screen has a display module, and the display module is composed of a liquid crystal display module and a micro light emitting diode display module. A display module selected from the group consisting of a mini light emitting diode display module, a quantum dot light emitting diode display module and an organic light emitting diode display module. The information processing device described in item 9 of the scope of the patent application is one selected from the group consisting of a smart phone, a portable computer, a vehicle-mounted computer, a wearable electronic device and an access control device device.

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