TWI754821B - Common voltage decoupling circuit, touch display integrated driver using the same, and touch display device - Google Patents

Abstract

A common voltage decoupling circuit, applied in a touch display integrated driver, comprises: a hysteresis comparator, which has a positive input terminal, a negative input terminal, and a first output terminal for outputting a first comparison signal and a second output terminal for outputting a second comparison signal, wherein the positive input terminal and the negative input terminal are correspondingly coupled to a common voltage and a common reference voltage; a PMOS transistor, with its gate and source correspondingly coupled to the first output terminal of the hysteresis comparator and a DC supply voltage; and an NMOS transistor, the gate and source of which are correspondingly coupled to the second output terminal of the hysteresis comparator and a ground voltage; Wherein, the drain electrode of the PMOS transistor and the drain electrode of the NMOS transistor are coupled to a common contact to provide a common voltage output terminal.

Description

Common voltage decoupling circuit, touch display integrated driver using the same, and touch display device

The present invention relates to the technical field of integrated driving circuits for touch display, and more particularly, to a common voltage decoupling circuit disposed at a touch receiving end of a touch display panel.

With the vigorous development and popularization of mobile devices, touch display devices have become one of the indispensable components. In the system architecture of the conventional touch display device, the touch and display functions are independently controlled by a set of touch chips and a set of display chips. However, with the development of technology, the architecture of the touch display device applied to the mobile device is gradually developed into an in-cell architecture. Therefore, in order to simplify the circuit structure and design of the touch driving circuit and the display driving circuit, in recent years, a touch and display integrated circuit (Touch And Display Integrated Circuit) with both touch driving function and display driving function has been developed. Driver Integration, TDDI).

FIG. 1 shows a schematic diagram of a conventional touch panel. As shown in FIG. 1 , since there are path impedances 22 ′ of different sizes between each touch receiving point 21 ′ on a panel 20 ′ and a touch display integrated driving integrated circuit 10 ′ (consists of traces and switch channels) Therefore, the driving force of the common voltage VCOM output by the touch display integrated driving integrated circuit 10 ′ to the touch receiving points 21 ′ on the panel 20 ′ will be inconsistent. Please refer to FIG. 2 at the same time, which shows an equivalent circuit diagram of a common voltage driving when the touch display integrated driving IC 10' of FIG. 1 operates in a display mode. As shown in FIG. 1 and FIG. 2 , during the screen display period, a common voltage driver 11' provides a common voltage source to directly drive each touch receiving point 21'. However, since there are metal traces and switch connections inside the touch display integrated driver IC 10', there is a path impedance 12' formed by traces and switch channels between any two adjacent touch receiving points 21'.

When the pixel data (SD1, SD2, SD3) is changed, a pixel driving unit (not shown in the figure) corresponding to each pixel data will output a step voltage Vstep, and the step voltage Vstep will pass through a parasitic The capacitor 23' and a path impedance 22' are coupled to a touch receiving point 21'; at this time, the parasitic A surge voltage Vimp1 will be generated between the capacitor 23' and the path impedance 22', and another surge voltage Vimp will be generated at the touch receiving point 21'. However, affected by the path impedance 22 ′ and the surge voltage Vimp, some of the touch receiving points 21 ′ cannot be pulled to the level of the common voltage VCOM_REF within a limited charging time, resulting in horizontal stripes or horizontal stripes on the display screen of the panel 20 . Vertical stripes.

At present, manufacturers of integrated driving ICs for touch display have proposed a solution to the above problem. FIG. 3 shows an equivalent circuit diagram of a common voltage driving when the improved touch display integrated driving IC 10a operates in a display mode. Compared with the touch display integrated driving integrated circuit 10 ′ shown in FIG. 2 , the improved touch display integrated driving integrated circuit 10 a shown in FIG. 3 further includes a plurality of NMOS transistors 10N′ and a plurality of PMOS transistors 10P'; wherein, the drain, gate and source of each of the NMOS transistors 10N' are correspondingly coupled to a DC supply voltage IOVCC, a common voltage VCOM_REF and a touch receiving point 21'. Moreover, the drain, gate and source of each of the PMOS transistors 10P' are correspondingly coupled to a ground voltage VCL, the common voltage VCOM_REF and the touch receiving point 21'. It is worth noting that, during the display of a picture, the touch receiving point 21 ′ is driven by the common voltage driver 11 ′, so that a step voltage Vstep of a pixel driving unit (not shown in the figure) passes through a When the parasitic capacitance 23' is coupled to the touch receiving point 21' and a surge voltage Vimp is generated at the touch receiving point 21', if the surge voltage Vimp has an upward pulse sufficient to turn on the PMOS transistor 10P', Then the PMOS transistor 10P' will provide a fast discharge path to shorten the transient time of the surge voltage. Conversely, if the surge voltage Vimp has a downward pulse sufficient to turn on the NMOS transistor 10N', the NMOS transistor 10N' will provide a fast charging path to shorten the transient time of the surge voltage Vimp. Accordingly, the touch receiving point 21' can return to the level of the common voltage VCOM_REF in a short time.

As can be seen from the above description, in the improved touch display integrated driving IC 10a, each of the touch receiving points 21' is coupled to an NMOS transistor 10N' and a PMOS transistor that are cascaded to each other. 10P'; according to this design, the level of the touch receiving point 21' can be quickly pulled up to the common voltage VCOM_REF by turning on the NMOS transistor 10N', and it can be quickly pulled down by turning on the PMOS transistor 10P' The level of the touch receiving point 21' is equal to the common voltage VCOM_REF. However, when the voltage difference between the touch receiving point 21' and the common voltage VCOM_REF When the voltage is less than a threshold voltage (Vth), the pull-up and/or pull-down effects of the NMOS transistor 10N' and/or the PMOS transistor 10P' on the level of the touch receiving point 21' may become unsatisfactory. On the other hand, since the base (Body) of the NMOS transistor 10N' and the base of the PMOS transistor 10P' must be coupled to the low potential and the high potential correspondingly, the NMOS transistor 10N' and the PMOS transistor 10P' are connected in series The structure will lead to serious base effect (Body effect).

Therefore, there is an urgent need in the art for a novel common voltage decoupling circuit.

An object of the present invention is to provide a common voltage decoupling circuit, which can effectively reduce the amount of capacitive pulse interference coupled to each touch receiving point of a touch panel through a simple and reliable circuit design , in order to achieve the effect of quickly stabilizing the common voltage level.

Another object of the present invention is to provide a common voltage decoupling circuit, which can significantly shorten the settling time of a common voltage signal.

In order to achieve the above object, a common voltage decoupling circuit is proposed, which includes: a hysteresis comparator, which has a positive input terminal, a negative input terminal, a first output terminal for outputting a first comparison signal, and a A second output terminal for outputting a second comparison signal, wherein the positive input terminal and the negative input terminal are correspondingly coupled to a common voltage and a common reference voltage; a PMOS transistor, with its gate and source correspondingly coupled the first output terminal of the hysteresis comparator and the DC supply voltage; and an NMOS transistor, the gate and the source of which are correspondingly coupled to the second output terminal of the hysteresis comparator and a ground voltage; The drain electrode of the PMOS transistor and the drain electrode of the NMOS transistor are coupled to a common point, and the common point is used as a common voltage output terminal of the common voltage decoupling circuit.

In one embodiment, when the difference between the common voltage and the common reference voltage exceeds a first offset voltage, the first comparison signal output by the hysteresis comparator through the first output terminal is at a low level , to turn on the PMOS transistor to perform a level pull-up operation on an output voltage of the common voltage output terminal.

In one embodiment, when the difference between the common voltage and the common reference voltage exceeds one At the second offset voltage, the second comparison signal output by the hysteresis comparator through the second output terminal is at a high level, so as to turn on the NMOS transistor and perform a level on the output voltage of the common voltage output terminal Pull down action.

In one embodiment, the common voltage output terminal is coupled to an input terminal of a multiplexer, and an output terminal of the multiplexer is coupled to a touch receiving point of a touch panel.

In addition, the present invention also provides an integrated touch display driver, which has the common voltage decoupling circuit as described above.

In addition, the present invention further provides a touch display device, which includes a touch display panel and a touch display integrated driver coupled to the touch display panel, wherein the touch display integrated driver has the common voltage decoupling as described above. circuit.

In a possible embodiment, the touch display device may be a liquid crystal touch display device, an LED touch display device or an OLED touch display device.

<The present invention>

10: Touch display integrated driver

20: Panel

21: Touch receiving point

22: Path Impedance

1: Common voltage decoupling circuit

11: Hysteresis comparator

11P: PMOS transistor

11N: NMOS transistor

CP: Common Contact

3: Multiplexer module

31: Multiplexer

<Knowledge>

10': touch display integrated driver IC

20': Panel

21': touch receiving point

22': path impedance

23': Parasitic capacitance

11': Common voltage driver

12': path impedance

10a: Improved touch display integrated driver IC

10N': NMOS transistor

10P': PMOS transistor

FIG. 1 is a schematic diagram of a conventional touch panel; FIG. 2 is an equivalent circuit diagram of a common voltage driving when the integrated driving IC of FIG. 1 operates in a display mode; FIG. 3 is an improved touch display An equivalent circuit diagram of a common voltage driving when the integrated driving IC works in a display mode; FIG. 4 shows a schematic diagram of a touch display device including the common voltage decoupling circuit of the present invention; FIG. A circuit structure diagram of a common voltage decoupling circuit, a multiplexer module and a panel; FIG. 6 shows a signal waveform diagram of a common voltage VCOM output by the common voltage output terminal of the common voltage decoupling circuit of FIG. 5; And FIG. 7 shows a signal waveform diagram of the common voltage VCOM used to input each touch receiving point in the circuit of FIG. 5 .

In order to enable your examiners to further understand the structure, features, purposes, and Its advantages are attached with drawings and detailed descriptions of preferred embodiments as follows.

4 shows a schematic diagram of a touch display device including the common voltage decoupling circuit of the present invention, wherein the touch display device can be a liquid crystal touch display device, an LED (light emitting diode; light emitting diode) touch display Device and OLED (organic light emitting diode; organic light emitting diode) touch display device. As shown in FIG. 4 , between each touch receiving point 21 on a panel 20 of the touch display device and a touch display integrated driver 10, there are path impedances 22 of different sizes (composed of traces and switch channels) Therefore, the present invention integrates a plurality of the common voltage decoupling circuits 1 into the touch display integrated driver 10 , so that the touch display integrated driver 10 can be provided by each of the common voltage decoupling circuits 1 . A stable and consistent common voltage VCOM is applied to each touch receiving point 21 on the panel 20 .

Please refer to FIG. 5 at the same time, which shows a circuit structure diagram of a plurality of common voltage decoupling circuits 1 , a multiplexer module 3 and a panel 20 of FIG. 4 . As shown in FIG. 4 and FIG. 5 , the common voltage decoupling circuit 1 of the present invention includes: a hysteresis comparator 11 , a PMOS transistor 11P and an NMOS transistor 11N, wherein the hysteresis comparator 11 has a positive input terminal, a a negative input terminal, a first output terminal for outputting a first comparison signal PG, and a second output terminal for outputting a second comparison signal NG, and the positive input terminal and the negative input terminal are correspondingly coupled to a The common voltage VCOM and a common reference voltage VCOM_REF. On the other hand, the gate and source of the PMOS transistor 11P are correspondingly coupled to the first output terminal of the hysteresis comparator 11 and the DC supply voltage IOVCC, and the gate and source of the NMOS transistor 11N are correspondingly coupled The second output terminal of the hysteresis comparator 11 is correspondingly coupled to a ground voltage VCL.

In addition, the drain of the PMOS transistor 11P and the drain of the NMOS transistor 11N are coupled to a common contact CP, and the common contact CP serves as a common voltage output terminal of the common voltage decoupling circuit 1 . 4 and 5, a multiplexer module 3 including a plurality of multiplexers 31 is coupled between a touch receiving point of the panel 20 and the touch display integrated driver 10, so that each The common voltage output terminals (ie, the common contact point CP) are all coupled to an input terminal of a multiplexer 31 , and an output terminal of each multiplexer 31 is coupled to a touch receiving point of the touch panel 20 . twenty one.

Continue to refer to FIGS. 4 and 5 , and please refer to FIG. 6 at the same time, which illustrates a common voltage output from the common voltage output terminal (ie, the common contact CP) of the common voltage decoupling circuit 1 of FIG. 5 Signal waveform diagram of VCOM. It can be found from the signal waveform of the common voltage VCOM shown in FIG. 6 that when the difference between the biased common voltage VCOM and the common reference voltage VCOM_REF exceeds a first offset OS- voltage, the hysteresis comparator 11 The first comparison signal PG outputted through its first output terminal will go low, so that the PMOS transistor 11P is turned on to execute an output voltage of the common voltage output terminal (ie, the common voltage VCOM) A level pull-up accelerates the level of the common voltage VCOM output through the common voltage output terminal to rise to the level of the common reference voltage VCOM_REF; on the contrary, when a biased common voltage VCOM is higher than the common reference voltage When the difference of VCOM_REF exceeds a second offset OS+ voltage, the second comparison signal NG output by the hysteresis comparator 11 through its second output terminal will go high, so that the NMOS transistor 11N is turned on to perform a level pull-down on the output voltage of the common voltage output terminal.

FIG. 7 shows a signal waveform diagram of the common voltage VCOM used to input each touch receiving point 21 in the circuit of FIG. 5 . In FIG. 7 , the dark gray signal curve is used to represent the signal waveform of the common voltage VCOM in the prior art (as shown in FIG. 2 ), and the black signal curve is used to represent the common voltage decoupling circuit 1 of the present invention. Signal waveform of the output common voltage VCOM. Comparing the dark gray signal curve and the black signal curve, it can be easily found that the coupling amount of the common voltage VCOM output by the common voltage decoupling circuit 1 of the present invention is significantly reduced by the capacitive interference pulse, and its settling time is significantly reduced. (Settling time) is also shorter than the common voltage signal of the prior art (as shown in FIG. 2 ). Therefore, the common voltage decoupling circuit 1 of the present invention is very suitable for the existing touch display integrated driver (TDDI driver IC) and various circuits that are easy to be coupled but need to quickly restore the voltage regulation level.

Thus, according to the above description, the technical solution of the present invention can be applied to a touch display integrated driver, and can be further applied to a touch display device. Moreover, according to the related design of the common voltage decoupling circuit 1 of the present invention disclosed above, it can be known that the present invention has the following advantages:

(1) The common voltage decoupling circuit 1 of the present invention can effectively reduce the coupling amount of the common voltage signal input to each touch receiving point 21 by the capacitive interference pulse through a simple and reliable circuit design, so as to achieve fast The effect of stabilizing the voltage level of the common voltage signal.

(2) Meanwhile, the common voltage decoupling circuit 1 of the present invention can also significantly shorten the settling time of the common voltage signal.

It must be emphasized that the above-mentioned disclosure in this case is a preferred embodiment, and any partial changes or modifications originating from the technical ideas of this case and easily inferred by those who are familiar with the art are within the scope of the patent of this case. category of rights.

To sum up, regardless of the purpose, means and effect of this case, it shows that it is completely different from the conventional technology, and its first invention is suitable for practical use, and indeed meets the patent requirements of the invention. Society is to pray for the best.

1: Common voltage decoupling circuit

11: Hysteresis comparator

11P: PMOS transistor

11N: NMOS transistor

20: Panel

21: Touch receiving point

22: Path Impedance

3: Multiplexer module

31: Multiplexer

CP: Common Contact

Claims (7)

A common voltage decoupling circuit, comprising: a hysteresis comparator with a positive input end, a negative input end, a first output end for outputting a first comparison signal, and a hysteresis device for outputting a second comparison signal a second output terminal, wherein the positive input terminal and the negative input terminal are correspondingly coupled to a common voltage and a common reference voltage; a PMOS transistor, whose gate and source are correspondingly coupled to the hysteresis comparator a first output terminal and a DC supply voltage; and an NMOS transistor whose gate and source are correspondingly coupled to the second output terminal of the hysteresis comparator and a ground voltage; wherein, the drain of the PMOS transistor The electrode and the drain electrode of the NMOS transistor are coupled to a common contact, and the common contact serves as a common voltage output terminal of the common voltage decoupling circuit. The common voltage decoupling circuit as described in claim 1, wherein when the difference between the common voltage and the common reference voltage exceeds a first offset voltage, the hysteresis comparator passes through the first output terminal The outputted first comparison signal is at a low level, so as to turn on the PMOS transistor and perform a level pull-up operation on an output voltage of the common voltage output terminal. The common voltage decoupling circuit as described in claim 2, wherein when the difference between the common voltage and the common reference voltage exceeds a second offset voltage, the hysteresis comparator passes through the second output terminal The outputted second comparison signal is at a high level, so as to turn on the NMOS transistor and perform a level pull-down operation on the output voltage of the common voltage output terminal. The common voltage decoupling circuit as described in claim 1, wherein the common voltage output terminal is coupled to an input terminal of a multiplexer, and an output terminal of the multiplexer is coupled to an output terminal of a touch panel. One touch receiving point. A touch display integrated driver has the common voltage decoupling circuit described in any one of items 1 to 4 of the patent application scope. A touch display device comprising a touch display panel and a touch display integrated driver coupled to the touch display panel, wherein the touch display integrated driver has any of the items 1 to 4 of the patent application scope. A common voltage decoupling circuit as described in one item. The touch display device described in item 6 of the claimed scope is a touch display device selected from the group consisting of a liquid crystal touch display device, an LED touch display device and an OLED touch display device.

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