Sensing circuit with signal compensation

Abstract

The present invention relates to a sensing circuit with signal compensation, comprising a first sensing element, a second sensing element, and a differential amplifier circuit. The differential amplifier circuit generates an output signal based on a common-mode voltage, a first sensing signal, and a second sensing signal through differential compensation. This reduces noise in the sensing circuit and effectively improves interference with display drive signals.

Description

Technical Field

[0001] The present invention relates to a sensing circuit, and more particularly to a sensing circuit for signal compensation. Background Art

[0002] With the advancement of technology, modern mobile devices have increasingly thinner display screens to meet market trends and public demand. This has led to a significant increase in parasitic capacitance between display electrodes and touchscreen panel electrodes. This increased parasitic capacitance can easily lead to saturation issues in the touch sensor output.

[0003] See also Figure 1 It is known that in the prior art, in order to solve the problem of output saturation caused by excessive parasitic capacitance, a large compensation capacitor C is required. OFTV or extremely high voltage V OFTV For compensation, see Figure 2 , or use a current source DAC, but the current source DAC needs to increase the current I DAC , can provide a large amount of compensation charge to try to eliminate the offset voltage, but no matter whether the compensation capacitor C OFTV Alternatively, current source DACs may be used for compensation. However, these compensation methods not only have high noise levels but also fail to eliminate the interference of the display drive signal on the touch screen panel, thereby affecting touch performance.

[0004] In view of the above problems, the present invention provides a sensing circuit with signal compensation. Through a differential amplifier circuit, the sensing circuit can reduce noise and effectively improve the interference problem of the display driving signal. Summary of the Invention

[0005] An object of the present invention is to provide a sensing circuit with signal compensation, which utilizes a differential amplifier circuit and performs differential compensation to improve the problem of parasitic capacitance between display electrodes and touch screen panel electrodes.

[0006] An object of the present invention is to provide a sensing circuit with signal compensation, comprising a first sensing element, a second sensing element, and a differential amplifier circuit. The differential amplifier circuit generates an output signal based on a common-mode voltage, a first sensing signal, and a second sensing signal through differential compensation. This not only reduces noise in the sensing circuit but also effectively improves interference with display drive signals.

[0007] To achieve the above objectives, the present invention provides a sensing circuit with signal compensation. By coupling a first sensing element and a second sensing element to a differential amplifier circuit, noise in the sensing circuit is eliminated, while preventing the common-mode noise from affecting the operation of the touch screen panel, thereby improving the quality of the display panel. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 : It is a circuit diagram of a first embodiment of the prior art;

[0009] Figure 2 : It is a circuit diagram of a second embodiment of the prior art;

[0010] Figure 3 : It is a circuit diagram of a sensing circuit with signal compensation according to a first embodiment of the present invention;

[0011] Figure 4 : It is a waveform diagram of the sensing circuit with signal compensation according to the first embodiment of the present invention; and

[0012] Figure 5 : It is a circuit diagram of a sensing circuit with signal compensation according to a second embodiment of the present invention.

[0013]

Figure number comparison

[0014] 100 Signal compensation sensing circuit

[0015] 10 Differential Amplifier Circuit

[0016] 20 First switching circuit

[0017] 30 Second switching circuit

[0018] 40 Differential Amplifier C10 first matching capacitor C20 second matching capacitor

[0019] C FB1 First capacitor

[0020] C FB2 Second capacitor

[0021] C OFTV Compensation capacitor

[0022] C OFTV1 First capacitor bank

[0023] C OFTV2 Second capacitor bank

[0024] C RX1 First sensing element

[0025] C RX2 Second sensing element

[0026] DAC current source

[0027] GND1 First ground terminal

[0028] GND2 Second ground terminal

[0029] IC driver components

[0030] I DAC Current

[0031] Panel touch screen panel

[0032] SW1 first switch

[0033] SW2 Second switch

[0034] SW3 third switch

[0035] SW4 Fourth switch

[0036] SW5 fifth switch

[0037] SW6 Sixth switch

[0038] SW7 seventh switch

[0039] SW8 Eighth switch

[0040] S1 First sensing signal

[0041] S2 Second sensing signal

[0042] T1 First conduction time

[0043] T2 Second on-time

[0044] V CM Common-mode voltage

[0045] VDD1 first driving voltage VDD2 Second driving voltage V OFTV Voltage V OP / V ON Output signal DETAILED DESCRIPTION

[0046] In order to further understand and appreciate the structural features and effects achieved by the present invention, preferred embodiments and detailed descriptions are provided as follows:

[0047] Certain terms are used in the specification and claims to refer to specific components. However, those skilled in the art will understand that the same component may be referred to by different terms. Furthermore, the specification and claims do not distinguish components by name, but rather by overall technical differences. Throughout the specification and claims, the term "including" is an open-ended term and should be interpreted as meaning "including, but not limited to." Furthermore, the term "coupled" encompasses any direct and indirect means of connection. Therefore, if a first device is described as being coupled to a second device, this means that the first device can be directly connected to the second device or indirectly connected to the second device through other devices or other means of connection.

[0048] According to conventional technology, whether the capacitor C OFTV Or use a current source DAC, both require a very high voltage V OFTV Or increase the current I DAC , can provide a large amount of compensation charge to eliminate the offset voltage. However, in addition to being noisy, this method cannot eliminate the interference of the display drive signal on the touch screen panel. Therefore, the present invention proposes a sensing circuit with signal compensation to solve the problem of increased circuit noise caused by parasitic capacitance between the display electrodes of the driver component IC and the electrodes of the touch screen panel in the conventional technology.

[0049] First, see Figure 3 , which is a circuit diagram of a sensing circuit with signal compensation according to a first embodiment of the present invention. As shown in the figure, the sensing circuit 100 with signal compensation according to the present invention comprises a first sensing element C RX1 A second sensing element C RX2 and a differential amplifier circuit 10. The differential amplifier circuit 10 is coupled to the first sensing element C RX1 and a second sensing element C RX2 , and according to the first sensing element C RX1 A first sensing signal S1 generated by the second sensing element, a second sensing signal S2 generated by the second sensing element, and a common mode voltage V CM , and generates an output signal V through a differential compensation OP and V ON In one embodiment of the present invention, the first sensing element C RX1 Receives a first driving voltage VDD1 to generate a first sensing signal S1 and a second sensing element C RX2 Receive a second driving voltage VDD2 to generate a second sensing signal S2, and transmit the second sensing signal S2 to the first sensing element C RX1 The capacitance value of the second sensing element C RX2The electrical characteristics of the capacitance values ​​are similar, so that the differential amplifier circuit 10 can compensate the first sensing signal S1, the second sensing signal S2 and the common mode voltage V CM Generate output signal V OP and V ON , that is, the common-mode noise of the differential amplifier circuit 10 is eliminated, thereby solving the parasitic capacitance generated between the display electrodes and the touch screen panel electrodes, and improving the noise problem of the sensing circuit.

[0050] Continuing from the above, in this embodiment, the signal compensation sensing circuit 100 of the present invention further includes a first switching circuit 20, which includes a third switch SW3, a fourth switch SW4, and a fifth switch SW5. One end of the third switch SW3, the fourth switch SW4, and the fifth switch SW5 is coupled to the first sensing element C. RX1 In one embodiment of the present invention, the other end of the third switch SW3 is coupled to a first ground terminal GND1, the other end of the fourth switch SW4 is coupled to the first driving voltage VDD1, and the other end of the fifth switch SW5 is coupled to the differential amplifier circuit 10. When the first driving voltage VDD1 is input to the first sensing element C via the fourth switch SW4, RX1 , or the first ground terminal GND1 is input to the first sensing element C via the third switch SW3 RX1 , which is used to generate a first sensing signal S1.

[0051] Continuing from the above, in this embodiment, the signal compensation sensing circuit 100 of the present invention includes a second switching circuit 30, which includes a sixth switch SW6, a seventh switch SW7, and an eighth switch SW8. One end of the sixth switch SW6, the seventh switch SW7, and the eighth switch SW8 is coupled to the second sensing element C. RX2 In one embodiment of the present invention, the other end of the sixth switch SW6 is coupled to a second ground terminal GND2, the other end of the seventh switch SW7 is coupled to the second driving voltage VDD2, and the other end of the eighth switch SW8 is coupled to the differential amplifier circuit 10. When the second driving voltage VDD2 is input to the second sensing element C via the seventh switch SW7, RX2 , or the second ground terminal GND2 is input to the second sensing element C via the sixth switch SW RX2 , which is used to generate the second sensing signal S2, wherein the first ground terminal GND1 of the present invention is substantially the same as the second ground terminal GND2, and the first driving voltage VDD1 is substantially the same as the second driving voltage VDD2. Further, for example, the first sensing element C of the present invention may be used. RX1 The capacitance value of the second sensing element C RX2The capacitance value characteristics are combined with the differential amplifier circuit 10 and a simple compensation capacitor array is added to compensate for the mismatch between the two. The first sensing element C is eliminated at the input of the first stage. RX1 and a second sensing element C RX2 In another embodiment, the first ground terminal GND1 is different from the second ground terminal GND2, and / or the first driving voltage VDD1 is different from the second driving voltage VDD2, and a simple compensation capacitor array is added to compensate the first sensing element C RX1 and a second sensing element C RX2 The mismatch at the input of the first stage eliminates the first sensing element C RX1 and a second sensing element C RX2 The common mode signal generated.

[0052] Continuing from the above, in this embodiment, the differential amplifier circuit 10 of the present invention further includes a differential amplifier 40 having a first input terminal, a second input terminal, a third input terminal, a first output terminal, and a second output terminal. In one embodiment of the present invention, the first input terminal of the differential amplifier 40 is used to receive the first sensing element C RX1 The second input terminal of the differential amplifier 40 is used to receive the first sensing signal S1 of the second sensing element C. RX2 The third input terminal of the differential amplifier 40 is used to receive the common mode voltage V CM , wherein the first input terminal of the differential amplifier 40 of the present invention receives the first sensing signal S1, and the second input terminal receives the second sensing signal S2, and the first sensing element C of the adjacent channel is used. RX1 With the second sensing element C RX2 The close characteristics are used to eliminate the common-mode noise of the differential amplifier 40. This is different from the previous technology that uses a single-ended input amplifier, which cannot eliminate the common-mode noise. It also avoids the output sensing signal from reaching saturation when the capacitance value of the sensing element is large.

[0053] Continuing from the above, in this embodiment, the differential amplifier circuit 10 of the present invention further includes a first capacitor C FB1 A second capacitor C FB2 , a first switch SW1 and a second switch SW2. In one embodiment of the present invention, the first capacitor C of the differential amplifier circuit 10 FB1 The first switch SW1 is connected in parallel and coupled between the first input terminal and the first output terminal of the differential amplifier circuit 10, and the first capacitor C FB1 Corresponding to the first sensing element C RX1 The first sensing signal S1 and the second capacitor C of the differential amplifier circuit 10 FB2The second switch SW2 is connected in parallel and coupled between the second input terminal and the second output terminal of the differential amplifier circuit 10, and the second capacitor C FB1 Corresponding to the second sensing element C RX2 The second sensing signal S2 is obtained, wherein the differential amplifier circuit 10 is based on the common mode voltage V CM , the first sensing signal S1 and the second sensing signal S2 are used to generate an output signal V OP and V ON .

[0054] Continuing from above, please see Figure 4 , which is a waveform diagram of the sensing circuit with signal compensation according to the first embodiment of the present invention. In this embodiment, the differential amplifier circuit 10 of the present invention can be divided into a touch screen panel charge / discharge stage and a charge transfer stage. During the touch screen panel charge / discharge stage, the fifth switch SW5 of the first switching circuit 20 and the eighth switch SW8 of the second switching circuit 30 are in a closed state. At this time, the fourth switch SW4 (or the third switch SW3) and the seventh switch SW7 of the second switching circuit 30 (or the sixth switch SW6 of the second switching circuit 30) are in a conducting state, so that the first sensing element C RX1 Charged to the first driving voltage VDD1 (or the first sensing element C RX1 discharge to the first ground terminal GND1) and the second sensing element C RX2 Charged to the second driving voltage VDD2 (or the second sensing element C RX2 discharge to the second ground terminal GND2), and at the same time the differential amplifier 40 is reset, so that the output signal V OP and V ON Approximately the common mode voltage V CM .

[0055] Continuing from the above, in this embodiment, when the differential amplifier circuit 10 of the present invention is in the charge transfer stage, the fifth switch SW5 of the first switching circuit 20 and the eighth switch SW8 of the second switching circuit 30 are in the on state, and the fourth switch SW4 of the first switching circuit 20 (or the third switch SW3 of the first switching circuit 20) and the seventh switch SW7 of the second switching circuit 30 (or the sixth switch SW6 of the second switching circuit 30) are in the off state, and the first switch SW1 and the second switch SW2 of the differential amplifier circuit 10 are in the off state at the same time, at this time, the first sensing element C RX1 Discharge from the first driving voltage VDD1 to the common mode voltage V CM , or the first sensing element C RX1 Charged from the first ground terminal GND1 to the common mode voltage V CM , and the second sensing element C RX2Discharge from the second driving voltage VDD2 to the common mode voltage V CM , or the second sensing element C RX2 Charged from the second ground terminal GND2 to the common mode voltage V CM , and charge transfer is performed through the differential amplifier circuit 10, and the first sensing signal S1 and the second sensing signal S2 are input to the differential amplifier 40 during a first conduction time T1 or a second conduction time T2, thereby generating an output signal V OP and V ON , expressed as the following formula (1):

[0056]

[0057] like Figure 3 As shown, according to the first capacitor C FB1 Corresponding to the first sensing element C RX1 The first sensing signal S1 offsets the second capacitor C FB2 Corresponding to the second sensing element C RX2 The second sensing signal S2 makes the output signal V OP and V ON Approximately equal to or equal to the common mode voltage V CM , thereby improving the noise generated by the parasitic capacitance between the display electrodes and the touch screen panel electrodes, and reducing the circuit noise problem.

[0058] Continuing from above, please see Figure 5 , which is a circuit diagram of a sensing circuit with signal compensation according to a second embodiment of the present invention. The sensing circuit 100 with signal compensation according to the present invention further comprises a first capacitor bank C OFTV1 and a second capacitor bank C OFTV2 , the first capacitor bank C OFTV1 Coupled to the first sensing element C RX1 and the differential amplifier circuit 10, and the first capacitor bank C OFTV1 The first matching capacitor C10 is used to match and compensate the first sensing element C RX1 With the differential amplifier circuit 10, the second capacitor bank C OFTV2 Coupled to the second sensing element C RX2 and the differential amplifier circuit 10, and the second capacitor bank C OFTV2 The at least one second matching capacitor C20 is used to match and compensate the second sensing element C RX2 and the differential amplifier circuit 10. In one embodiment of the present invention, the first sensing element C of the adjacent channel is used. RX1 Close to the second sensing element C RX2 , and through the first capacitor bank C OFTV1At least one first matching capacitor C10 and a second capacitor bank C OFTV2 At least one second matching capacitor C20 is provided to eliminate the common mode signal input to the differential amplifier, so that the output signal V OP and V ON Approximately the common mode voltage V CM , and is used to solve the problem of output saturation, which is expressed as the following formula (2):

[0059]

[0060] like Figure 5 As shown, by the first capacitor bank C OFTV1 One end of the first sensing element C is coupled to RX1 , and the first capacitor bank C OFTV1 One end only needs to be grounded, and the second capacitor bank C OFTV2 One end of the sensor is coupled to the second sensing element C RX2 , and the second capacitor bank C OFTV2 One end of the touch screen panel only needs to be grounded, and there is no need to switch the capacitor. RX1 Different from the second sensing element C RX2 The present invention sets a first capacitor bank C OFTV1 and the second capacitor bank C OFTV2 , so that the first sensing element C RX1 +First capacitor bank C OFTV1 =Second sensing element C RX2 + Second capacitor bank C OFTV2 , to solve the original first sensing element C RX1 Different from the second sensing element C RX2 The mismatch problem is solved, so that the noise introduced by the compensation circuit is greatly reduced compared with the conventional technology.

[0061] In summary, the sensing circuit with signal compensation of the present invention includes a first sensing element, a second sensing element, and a differential amplifier circuit. The differential amplifier circuit generates an output signal based on a common-mode voltage, a first sensing signal, and a second sensing signal through differential compensation. This not only reduces noise in the sensing circuit but also effectively improves interference with display drive signals. Furthermore, the provision of a first capacitor bank and a second capacitor bank of the present invention effectively matches the first sensing element and the second sensing element and simultaneously compensates the differential amplifier circuit, thereby significantly reducing noise in the compensated differential amplifier circuit.

[0062] The above is only a preferred embodiment of the present invention and is not intended to limit the scope of the present invention. All equivalent changes and modifications in the shape, structure, characteristics and spirit described in the scope of the claims of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A sensing circuit with signal compensation, characterized in that: It includes: a first sensing element receiving a first driving voltage to generate a first sensing signal; a second sensing element receiving a second driving voltage to generate a second sensing signal; a differential amplifier circuit coupled to a common-mode voltage, the first sensing element, and the second sensing element, the differential amplifier circuit generating an output signal through differential compensation according to the common-mode voltage, the first sensing signal, and the second sensing signal; as well as a first switching circuit comprising: a third switch, one end of which is coupled to the first sensing element, and the other end of which is coupled to a first ground; a fourth switch, one end of which is coupled to the first sensing element, and the other end of which is coupled to a first driving voltage; as well as A fifth switch has one end coupled to the first sensing element, and the other end coupled to the differential amplifier circuit.

2. The sensing circuit with signal compensation as claimed in claim 1, wherein: Also includes: a first capacitor bank coupled between the first sensing element and the differential amplifier circuit, the first capacitor bank including at least one first matching capacitor; and A second capacitor bank is coupled between the second sensing element and the differential amplifier circuit, and the second capacitor bank includes at least one second matching capacitor.

3. The sensing circuit with signal compensation as claimed in claim 1, wherein: in, The differential amplifier circuit further comprises: a differential amplifier having a first input terminal, a second input terminal, a third input terminal, a first output terminal, and a second output terminal, wherein the first input terminal of the differential amplifier receives the first sensing signal of the first sensing element, the second input terminal of the differential amplifier receives the second sensing signal of the second sensing element, and the third input terminal of the differential amplifier receives the common-mode voltage; a first capacitor coupled between the first input terminal and the first output terminal of the differential amplifier, the first capacitor corresponding to the first sensing signal of the first sensing element; as well as a second capacitor coupled between the second input terminal and the second output terminal of the differential amplifier, the second capacitor corresponding to the second sensing signal of the second sensing element; The differential amplifier circuit generates the output signal according to the common mode voltage, the first sensing signal and the second sensing signal.

4. The sensing circuit with signal compensation as claimed in claim 3, wherein: Also includes: a first switch coupled to the first capacitor and coupled to the first input terminal and the first output terminal of the differential amplifier; and A second switch is coupled to the second capacitor and to the second input terminal and the second output terminal of the differential amplifier.

5. A sensing circuit with signal compensation, characterized in that: It includes: a first sensing element receiving a first driving voltage to generate a first sensing signal; a second sensing element receiving a second driving voltage to generate a second sensing signal; a differential amplifier circuit coupled to a common-mode voltage, the first sensing element, and the second sensing element, the differential amplifier circuit generating an output signal based on the common-mode voltage, the first sensing signal, and the second sensing signal through differential compensation, wherein the differential compensation cancels the second sensing signal by causing the first sensing signal to be offset; as well as a second switching circuit comprising: a sixth switch, one end of which is coupled to the second sensing element, and the other end of which is coupled to a second ground; a seventh switch, one end of which is coupled to the second sensing element, and the other end of which is coupled to a second driving voltage; as well as An eighth switch has one end coupled to the second sensing element, and the other end coupled to the differential amplifier circuit.

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