CN101833042B - Capacitance value measuring circuit and its integrated control circuit - Google Patents

Abstract

A capacitance measurement circuit is used for measuring capacitance of a capacitor to be measured, wherein the capacitor to be measured is coupled to an end point, and the end point is provided with an operation voltage signal. The capacitance measuring circuit comprises a multi-power supply circuit, a charging and discharging path and a comparator circuit. The multi-power supply circuit is used for responding to the control signal and selectively providing one of a plurality of power supply voltage signals as an output voltage signal output. The charging and discharging path is used for providing an output voltage signal with a first voltage level to perform charging operation on the capacitor to be tested and providing an output voltage signal with a second voltage level to perform discharging operation on the capacitor to be tested so as to control the level of the operating voltage signal. The comparator circuit receives and compares the operation voltage signal and the reference voltage signal to correspondingly generate a digital signal indicating the capacitance value of the capacitor to be measured. The invention also provides a comprehensive control circuit applying the capacitance value measuring circuit.

Description

Capacitance value measuring circuit and its integrated control circuit

technical field

The invention relates to a capacitance measuring circuit, and in particular to a capacitance measuring circuit which can be integrated with a display driver circuit.

Background technique

Traditionally, most of the user control interface devices are realized by mechanical switches. Because the traditional mechanical switch needs to be in direct contact with the user to operate in response to the user's control command, the traditional mechanical device has the disadvantage of being prone to structural damage during the user's operation.

In today's era of rapid technological development, tactile switches already exist. Traditionally, the touch switch is, for example, a capacitive switch, which is controlled by sensing the change of the capacitance value of the capacitor to be measured with the approach of the user. In the prior art, a capacitance measurement circuit is used to sense the capacitance change of the capacitance switch, so as to achieve corresponding control in response to user operations. However, how to design a low-cost capacitance measurement circuit has become one of the directions in this field.

Contents of the invention

The invention relates to a capacitance value measurement circuit, which performs capacitance value measurement operations on capacitances to be measured in different value ranges according to voltage signals of different levels provided by multiple power supply circuits. The multi-power supply circuit can be a Gamma voltage supply circuit in the display driver, and the capacitance measuring circuit related to the present invention can also be effectively integrated in the display driver. Therefore, compared with the traditional capacitance measuring circuit, the capacitance measuring circuit related to the present invention has the advantages of lower cost and capable of performing capacitance measuring operations on different values of the capacitance to be measured by receiving input voltages of different levels.

According to the present invention, a capacitance value measuring circuit is provided, which is used for measuring the capacitance value of a capacitor to be measured. The capacitor to be measured is coupled to an terminal, and the terminal has an operating voltage signal. The capacitance measurement circuit includes multiple power supply circuits, charging and discharging paths and a comparator circuit. The multiple power supply circuit is used for selectively providing one of multiple power supply voltage signals as an output voltage signal in response to the control signal. The charging and discharging path is used to provide an output voltage signal with a first voltage level to charge the capacitor to be measured, and provide an output voltage signal with a second voltage level to discharge the capacitor to be measured, so as to control the level of the operating voltage signal . The comparator circuit receives and compares the operating voltage signal and the reference voltage signal to correspondingly generate a digital signal indicating the capacitance value of the capacitor to be tested.

According to the capacitance measurement circuit of the present invention, it further includes a processing circuit, which is used to calculate and obtain the capacitance value of the capacitor to be measured in response to the digital signal.

According to the capacitance measurement circuit of the present invention, the multi-power supply circuit is a gamma voltage supply circuit for providing multiple gamma voltages as corresponding multiple power supply voltage signal outputs.

According to the capacitance measurement circuit of the present invention, the other terminal of the capacitance to be measured receives a ground voltage signal.

According to the capacitance measuring circuit of the present invention, the charging and discharging path includes a load circuit, and the load circuit is connected in series with the capacitance to be measured.

According to the present invention, an integrated control circuit is provided, which is applied in a touch display panel. The integrated control circuit includes a multi-power supply circuit, a capacitance value measurement circuit and a display driving circuit. The multi-power supply circuit is used for selectively providing one of the plurality of gamma voltage signals as an output voltage signal in response to the control signal. The capacitance value measuring circuit is used to measure the capacitance value of the capacitor to be measured, and the capacitor to be measured is coupled to an terminal, and the terminal has an operating voltage signal. The capacitance value measuring circuit includes a charging and discharging path and a comparator circuit. The charging and discharging path is used to provide an output voltage signal with a first voltage level to charge the capacitor to be measured, and provide an output voltage signal with a second voltage level to discharge the capacitor to be measured, so as to control the level of the operating voltage signal . The comparator circuit receives and compares the operating voltage signal and the reference voltage signal to correspondingly generate a digital signal indicating the capacitance value of the capacitor to be tested. The display driving circuit is used to provide a gamma voltage to drive the touch display panel to display a display image.

According to the integrated control circuit of the present invention, in one embodiment, it further includes a processing circuit, which is used to calculate and obtain the capacitance value of the capacitor to be measured in response to the digital signal.

According to the integrated control circuit of the present invention, in one embodiment, the multiple power supply circuits are gamma voltage supply circuits, and the multiple power supply circuits are integrated in the display driving circuit.

According to the integrated control circuit of the present invention, in one embodiment, the other terminal of the capacitor to be measured receives a ground voltage signal.

According to the integrated control circuit of the present invention, in one embodiment, the charging and discharging path includes a load circuit, and the load circuit is connected in series with the capacitor to be measured.

According to the integrated control circuit of the present invention, in one embodiment, the display driving circuit is a source driving circuit (Source Driver).

According to the integrated control circuit of the present invention, in one embodiment, the capacitance measuring circuit and the display driving circuit are realized by the same integrated circuit (IC).

In order to make the above content of the present invention more obvious and understandable, the preferred embodiments are specifically cited below, and in conjunction with the accompanying drawings, the detailed description is as follows:

Description of drawings

FIG. 1 shows a schematic diagram of a capacitance measurement circuit according to an embodiment of the present invention.

FIG. 2 shows a timing diagram of relevant signals of the capacitance measuring circuit 1 in FIG. 1 .

FIG. 3 shows a block diagram of an integrated control circuit according to an embodiment of the present invention.

FIG. 4 shows another block diagram of an integrated control circuit according to an embodiment of the present invention.

Detailed ways

The capacitance measurement circuit in the embodiment of the present invention responds to the power signal provided by the multi-power supply circuit to perform a capacitance measurement operation on the capacitance to be measured.

Please refer to FIG. 1 and FIG. 2 , FIG. 1 shows a schematic diagram of a capacitance measuring circuit according to an embodiment of the present invention, and FIG. 2 shows a timing diagram of relevant signals of the capacitance measuring circuit 1 in FIG. 1 . The capacitance measuring circuit 1 is used to measure the capacitance of the capacitance Cc to be measured. One end of the capacitor Cc to be tested receives the ground voltage, and the other end is coupled to the terminal Ed. The terminal Ed has an operating voltage signal SOP. The capacitance measurement circuit 1 includes a multi-power supply circuit 12 , a charging and discharging path 14 , a comparator circuit 16 and a processing circuit 18 .

The multi-power supply circuit 12 generates a plurality of fixed-voltage power signals, and is used to selectively provide a high-voltage power signal and a low-voltage power signal in these fixed-voltage power signals as an output voltage signal SVO, so that the output voltage signal SVO has High signal level and low signal level.

In the initial operating state, the processing circuit 18 provides an initial state control signal SC to the multi-power supply circuit 12 to control the multi-power supply circuit 12 to select a voltage power signal with a voltage level HV1 as its high-voltage power signal, and select a voltage with The voltage power signal of level LV is its low voltage power signal. In other words, in the initial operating state, the high voltage and low voltage levels of the output voltage signal SVO are equal to the voltage levels HV1 and LV respectively.

In one example of operation, the multi-power supply circuit 12 further provides an output voltage signal SVO having a high voltage level (voltage level HV1) in response to the first state of the control signal SC; and provides an output voltage signal SVO in response to the second state of the control signal SC. The output voltage signal SVO has a low voltage level (voltage level LV).

The charging and discharging path 14 includes, for example, a load circuit R coupled between the multi-power supply circuit 12 and the terminal Ed. The charging and discharging path 14 is used to provide the output voltage signal SVO with the voltage level HV1 to the terminal Ed for charging the capacitor Cc to be measured, so that the level of the operating voltage signal SOP is close to the voltage level HV1 .

The charge-discharge path 14 further provides an output voltage signal SVO with a voltage level LV to the terminal Ed for discharging the capacitor Cc to be measured so that the level of the operating voltage signal SOP is close to the voltage level LV.

The comparator circuit 16 receives and compares the operating voltage signal SOP and the reference voltage signal SRF to correspondingly generate a digital signal SDG indicating the capacitance value of the capacitor Cc to be measured. For example, the reference voltage signal SRF has a voltage level RV, which is between the voltage levels HV1 and LV. When the level of the operating voltage signal SOP is lower than the voltage level RV, the comparator circuit 16 provides a digital signal SDG of a low voltage level; when the level of the operating voltage signal SOP is higher than the voltage level RV, the comparator circuit 16 A digital signal SDG of a high voltage level is provided.

For example, the processing circuit 18 further calculates the capacitance value of the capacitor under test Cc according to the number of times the level of the digital signal SDG is switched between the high voltage level and the low voltage level in the operation unit time.

In one example, the processing circuit 18 generates and provides a control signal SC having a first state to the multi-power supply circuit 12 in response to the digital signal SDG having a low level, so as to control the multi-power supply circuit 12 to provide an output voltage having a high voltage level. Signal SVO. The processing circuit 18 further generates and provides a control signal SC having a second state to the multi-power supply circuit 12 in response to the digital signal SDG having a high level to control the multi-power supply circuit 12 to provide the output voltage signal SVO having a low voltage level.

In this embodiment, although only the multi-power supply circuit 12 responds to the first and second states indicated by the control signal SC to provide a high voltage level (for example, equal to the voltage level HV1) and a low voltage level (for example, The situation of the output voltage signal SVO equal to the voltage level LV) is taken as an example for illustration, however, the multi-power supply circuit 12 of the present embodiment is not limited thereto. In another example, the multi-power supply circuit 12 of this embodiment can also perform corresponding operations in response to other states indicated by the control signal SC.

For example, when the capacitance of the capacitor Cc to be tested is too high, the output voltage signal SVO provided by the multi-power supply circuit 12 cannot raise the voltage on the terminal Ed from a low level to exceed the voltage level RV within the operation unit time. voltage, or pull down the voltage on the terminal Ed from a high level to a voltage lower than the voltage level RV. In other words, at this moment, the output voltage signal SVO cannot provide sufficient driving capability to drive and change the voltage stored at both ends of the capacitor Cc to be measured during the operation unit time. In this way, the number of times the level of the digital signal SDG is switched between the high voltage level and the low voltage level is zero, and the processing circuit 18 cannot obtain the capacitance value of the capacitor under test Cc according to the digital signal SDG at this time.

In this case, the processing circuit 18 generates and provides a control signal SC indicating a measurement error state to the multi-power supply circuit 12 in response to the digital signal SDG having a high voltage level or a low voltage level. In response to the control signal of the measurement error state indicated by the control signal SC, the multi-power supply circuit 12 selects other high-voltage power supply voltage signals among these fixed-voltage power supply signals to output as the output voltage signal SVO. For example, the multi-power supply circuit 12 selects the power voltage signal with the voltage level HV2 among the power voltage signals to output as the output voltage signal SVO. The voltage level HV2 is greater than the voltage level HV1, so as to provide an output voltage signal SVO with better driving capability to drive the voltage Cc under test.

Next, the multi-power supply circuit 12 responds to the first state of the control signal SC to provide a voltage power signal with a voltage level HV2 as an output voltage signal SVO, and responds to the second state of the control signal SC to provide a voltage signal with a voltage level LV. The voltage supply signal is output as an output voltage signal.

If the multi-power supply circuit 12 continues to receive the control signal SC indicating the measurement error state, the multi-power supply circuit 12 repeats the above operations to select the voltage power signal with the voltage level HV3 as the output voltage signal SVO. The voltage level HV3 is higher than the voltage level HV2.

In this embodiment, although the operation of adjusting the high signal level of the multi-power supply circuit 12 to the voltage levels HV1-HV3 in response to the control signal SC is used as an example for illustration, however, the multi-power supply circuit 12 of this embodiment The adjustment is not limited to the high signal level of the control signal SC, but the low signal level of the control signal SC can also be adjusted. Therefore, the driving capability of the output voltage signal SVO can also be improved.

Please refer to FIG. 3 , which shows a block diagram of an integrated control circuit according to an embodiment of the present invention. In one example, the multi-power supply circuit 12 in the original capacitance measurement circuit 1 can be realized by the digital-to-analog converter DA in the display driving circuit 2, and the capacitance measurement circuit 1' and the display driving circuit 2 are integrated to form a Integrated control circuit 10.

The integrated control circuit 10 is applied in the touch display 200 , which includes the touch display panel 100 . The display driving circuit 2 includes, for example, a data driver (Data Driver), which is controlled by a timing controller (Timing Controller) TC to provide data to the touch-sensitive display panel 100 .

For example, the digital-to-analog converter DA includes a gamma voltage supply circuit, which is used to convert the digital signal generated by the shift register (Shift Register) SR and the data latch (Latch) DL in the display driving circuit 2 to An analog signal is obtained and output via the output buffer OB.

The capacitance measurement circuit 1' includes a measurement circuit 1a and a processing circuit 1b. The measurement circuit 1 a includes, for example, the charging and discharging paths and comparator circuits shown in FIG. 1 . The charging and discharging path is coupled to the comparator circuit and a touch switch in the touch panel 100 . The charging and discharging path further receives and performs charging and discharging operations on the touch switch according to the output voltage signal SVO′ provided by the digital-to-analog converter DA to generate a corresponding digital signal SDG′.

The processing circuit 1b performs operations similar to the processing circuit 18 in FIG. 1 to generate a control signal SC' to control the digital-to-analog converter DA. The integrated control circuit 10 of this embodiment can integrate the capacitance measurement circuit 1 ′ and the display driving circuit 2 by sharing the digital-to-analog converter DA including the gamma voltage supply circuit. In one example, the integrated control circuit 10 is realized by an integrated circuit, for example.

Please refer to FIG. 4 , which shows another block diagram of an integrated control circuit according to an embodiment of the present invention. In another example, the capacitance value measuring circuit 1 ″ integrated in the integrated control circuit 10 ′ is, for example, driven by the external multi-power supply circuit 12 ′ to measure the corresponding capacitance value of the touch-sensitive display 200 ′. Measurement operation: The display driver 2' is controlled by the timing controller TC' to drive the touch-sensitive display panel 100' to display image images.

The capacitance measurement circuit of the embodiment of the present invention performs capacitance measurement operations on the capacitances to be measured in different value ranges according to the voltage signals of different levels provided by the multi-power supply circuit. However, the capacitance value measurement circuit of the embodiment of the present invention further includes a multi-power supply circuit for adjusting the high signal or low signal level of the output voltage signal in response to the control signal indicating the measurement error state, so as to adjust the capacitance of the embodiment of the present invention. Capacitance value measurable range of the value measurement circuit. Therefore, compared with the traditional capacitance measurement circuit, the capacitance measurement circuit of the embodiment of the present invention has the advantages of adjustable capacitance measurement range, wider capacitance measurement range, and automatic adjustment of the capacitance value in response to the feedback control signal. Advantages of measuring range.

In addition, the capacitance measurement circuit in the embodiment of the present invention can also use the digital-to-analog converter in the display driving circuit as a multi-power supply circuit, and the capacitance measurement circuit in the embodiment of the present invention can also be effectively integrated in the display driving circuit . Therefore, compared with the traditional capacitance measurement circuit, the capacitance measurement circuit related to the present invention has the advantages of lower cost and can be integrated with the display driving circuit.

In summary, although the present invention has been disclosed as above with preferred embodiments, they are not intended to limit the present invention. Those skilled in the art to which the present invention belongs should be able to make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention should be determined by the scope defined by the appended claims.

Explanation of main component symbols

1, 1′, 1″: capacitance measurement circuit 12, 12′: multi-power supply circuit

14: Charge and discharge path 16: Comparator circuit

18. 1b: Processing circuit Cc: Capacitance to be tested

200, 200′: touch display TC, TC′: timing controller

100, 100': touch display panel 10, 10': integrated control circuit

2, 2': display drive circuit OB: output buffer

DA: Digital to Analog Converter DL: Data Latch

SR: shift register 1a: measurement circuit.

Claims (12)

1. A capacitance value measuring circuit, used for measuring the capacitance value of the capacitance to be measured, the capacitance to be measured is coupled to an end point, the end point has an operating voltage signal, and the capacitance value measurement circuit includes: A multi-power supply circuit, used for selectively providing one of a plurality of power supply voltage signals as an output voltage signal in response to a control signal; A charging and discharging path, configured to provide the output voltage signal with a first voltage level to charge the capacitor under test, and provide the output voltage signal with a second voltage level to charge the capacitor under test a discharge operation to control the level of the operation voltage signal; and The comparator circuit receives and compares the operating voltage signal and the reference voltage signal to correspondingly generate a digital signal indicating the capacitance value of the capacitor to be measured. 2. The capacitance measuring circuit according to claim 1, further comprising: The processing circuit is used to obtain the capacitance value of the capacitor to be measured through calculation in response to the digital signal. 3. The capacitance measurement circuit according to claim 1, wherein the multiple power supply circuit is a gamma voltage supply circuit, configured to provide multiple gamma voltages as the corresponding multiple power supply voltage signal outputs. 4. The capacitance measuring circuit according to claim 1, wherein the other terminal of the capacitance to be measured receives a ground voltage signal. 5. The capacitance measuring circuit according to claim 1, wherein the charging and discharging path comprises a load circuit, and the load circuit is connected in series with the capacitance to be measured. 6. An integrated control circuit applied in a touch display panel, the integrated control circuit comprising: A multiple power supply circuit is used to selectively provide one of multiple gamma voltage signals as an output voltage signal in response to a control signal; The capacitance value measuring circuit is used to measure the capacitance value of the capacitor to be measured, the capacitor to be measured is coupled to an terminal, and the terminal has an operating voltage signal, and the capacitance value measuring circuit includes: A charging and discharging path, configured to provide the output voltage signal with a first voltage level to charge the capacitor under test, and provide the output voltage signal with a second voltage level to charge the capacitor under test a discharge operation to control the level of the operating voltage signal; and a comparator circuit, receiving and comparing the operating voltage signal and the reference voltage signal to correspondingly generate a digital signal indicating the capacitance value of the capacitor to be measured; and The display driving circuit is used to provide the plurality of gamma voltages to drive the touch-sensitive display panel to display image images. 7. The integrated control circuit according to claim 6, further comprising: The processing circuit is used to obtain the capacitance value of the capacitor to be measured through calculation in response to the digital signal. 8. The integrated control circuit according to claim 6, wherein: The multi-power supply circuit is a gamma voltage supply circuit, and the multi-power supply circuit is integrated in the display driving circuit. 9. The integrated control circuit according to claim 6, wherein the other terminal of the capacitor under test receives a ground voltage signal. 10. The integrated control circuit according to claim 6, wherein the charging and discharging path comprises a load circuit, and the load circuit is connected in series with the capacitor under test. 11. The integrated control circuit according to claim 6, wherein the display driving circuit is a source driving circuit. 12. The integrated control circuit according to claim 6, wherein the capacitance measuring circuit and the display driving circuit are realized by the same integrated circuit.

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