CN102541330B - Touch screen and touch display device - Google Patents

Abstract

The present invention provides a touch screen, comprising a first substrate, a touch structure layer, an insulating medium layer and a common electrode layer sequentially formed on the first substrate; the touch structure layer is a single-layer capacitive touch structure , including a plurality of driving electrodes and a plurality of sensing electrodes arranged at intervals in strips; the common electrode layer includes a plurality of first common electrodes disposed opposite to the driving electrodes and a plurality of first common electrodes disposed opposite to the sensing electrodes the second common electrodes; a first resistor is coupled between the plurality of first common electrodes and the ground terminal, and a second resistor is coupled between the plurality of second common electrodes and the ground terminal. In the touch screen of the present invention, the first resistor and the second resistor are respectively coupled between the driving ground, the sensing ground, and the ground terminal to realize the optimization of the touch signal.

Description

A kind of touch screen and touch display device

field of invention

The present invention relates to the field of touch technology, in particular to an embedded mutual capacitance sensing touch screen and a touch display device including the touch screen.

Background technique

At present, according to different combinations of the touch screen and the liquid crystal display device, the touch screen can be divided into two types, one is an external touch screen, and the other is an embedded touch screen.

The external touch screen and the display device are manufactured separately and then assembled together. This will inevitably increase the thickness of the display screen, and due to the addition of several layers of transparent glass or film, the display light transmittance and contrast will also decrease significantly. In addition, the cost of this approach is also higher.

In order to make LCD display devices with touch screens thinner, have better display effects and cost advantages, an in-cell touch panel (In-cell touch panel) was born. FIG. 1 is a schematic structural diagram of a touch display device using an embedded touch screen in the prior art.

As shown in FIG. 1 , the touch display device includes an in-cell touch screen 200, a lower substrate 27 disposed opposite to the in-cell touch screen 200; a liquid crystal layer 29 disposed between the in-cell touch screen 200 and the second substrate 27; The surface of the lower substrate 27 facing the liquid crystal layer 29 is provided with a thin film transistor (TFT) array layer 28 .

The in-cell touch screen 200 includes a first substrate 26, a touch structure layer 21, an insulating medium layer 22 and a common electrode layer 23 formed sequentially on the first substrate 26;

Wherein, the first substrate 26 and the second substrate 27 may be glass substrates, the common electrode layer 23 may be an ITO layer, and the insulating medium layer 22 may be a color filter film.

The touch structure layer 21 in the prior art may be a single-layer capacitive touch structure (as shown in FIG. 2 ). It can be seen from FIG. 2 that the touch structure layer 21 includes a plurality of driving electrodes and a plurality of sensing electrodes 2 a , 2 b , 2 c , and 2 d arranged at intervals in strips. Each driving electrode is composed of electrodes 1a', 1b', 1c', 1d', 1e' separated from each other; the electrode 1a' in each driving electrode is surrounded by a plurality of sensing electrodes 2a, 2b, 2c, 2d in the working area of the touch screen Separated and connected together in the peripheral area to form the driving line 1a; the same is true for the electrodes 1b', 1c', 1d', and 1e' in the driving electrodes, which respectively form the driving lines 1b, 1c, 1d, and 1e. In this way, the driving lines 1a, 1b, 1c, 1d, 1e still form a matrix structure with the sensing electrodes 2a, 2b, 2c, 2d. A mutual capacitance 12 is formed at the intersection of each driving line 1 and the sensing electrode 2 .

There is a problem with the in-cell touch screen 200 in the prior art: the distance between the touch structure layer 21 and the common electrode layer 23 is very short (only a few microns), so the capacitance between them will be large. The equivalent circuit at the intersection of each driving line 1 and sensing electrode 2 in the prior art in-cell touch screen 200 is shown in FIG. 3 . Each intersection is coupled with a mutual capacitance 12 . Both the driving line 1 and the sensing electrode 2 have a parasitic capacitance 13 to ground, and the driving signal source 3 provides a driving signal; the detection circuit 6 is a charge amplifier, which converts the current 14 on the sensing electrode into a voltage signal 15 for output. When a finger touches, the mutual capacitance 12 changes, which causes the output current 14 to change, thereby causing the output voltage 15 to change.

Because in the structure of the in-cell touch screen 200 , the parasitic capacitance 13 is often very large, which will generate an interference signal 18 , which is ineffective for touch detection. At this time, the resistance 16 and the inductance 17 of the common electrode layer 23 cannot be ignored. It has been proved by simulation that when the parasitic capacitance 13 reaches 500pF, only the resistance 16 of 2 ohms and the inductance of 50 nanohenries can have an extremely adverse effect on the touch signal, and such small resistance and inductance are basically unavoidable.

For the above problem, there is a solution, which is to divide the common electrode layer 23 into multiple strip electrodes (as shown in FIG. 4 ). The common electrode layer 23 includes a plurality of first common electrodes 24 and a plurality of second common electrodes 25 arranged at intervals in strips; the first common electrodes 24 include common electrodes 24a, 24b, 24c, and 24d; the first common electrodes 25 include common Electrodes 25a, 25b, 25c and 25d. A plurality of first common electrodes 24 are arranged opposite to a plurality of driving electrodes, and each driving electrode composed of electrodes 1a', 1b', 1c', 1d', 1e' is respectively connected to the common electrodes 24a, 24a, 24b, 24c, 24d are arranged facing each other in the direction of light transmission, preferably overlapped; the sensing electrodes 2a, 2b, 2c, 2d are respectively connected to the common electrodes 25a, 25b, 25c, 25d of the second common electrode 25 in the direction of light transmission. Upright setting, preferably overlapping setting. The common electrodes 24a, 24b, 24c, and 24d of the first common electrode 24 are coupled to the ground terminal after being connected in parallel in the peripheral area; to ground.

At this time, the equivalent circuit at the intersection of each driving line 1 and the sensing electrode 2 in the in-cell touch screen 200 is shown in FIG. 5 . In Fig. 5, the parasitic capacitance 13 between the drive line 1 and the first common electrode 24 is grounded through the resistance and inductance 19 of the first common electrode; the parasitic capacitance 13 between the sensing electrode 2 and the second common electrode 25 is grounded through the resistance and inductance of the second common electrode 20 to ground.

All the first common electrodes 24 corresponding to the driving electrodes can be defined as the driving ground, and all the second common electrodes 25 corresponding to the sensing electrodes can be defined as the sensing ground. The resistance and inductance 19 of the driving ground and the resistance and inductance 20 of the driving ground will still affect the detection signal, so that the detection signal cannot be optimized.

Contents of the invention

The technical problem to be solved by the present invention is that the resistance and inductance of the driving ground and the resistance and inductance of the sensing ground in the existing embedded touch screen affect the detection signal, so that the detection signal cannot be optimized.

In order to solve the above technical problems, the present invention provides a touch screen, including a first substrate, a touch structure layer formed on the first substrate in sequence, an insulating medium layer and a common electrode layer; the touch structure layer is a single A layer capacitive touch structure, including a plurality of driving electrodes and a plurality of sensing electrodes arranged at intervals in strips; the common electrode layer includes a plurality of first common electrodes facing the driving electrodes and a plurality of The sensing electrodes are opposite to the second common electrodes; a first resistor is coupled between the plurality of first common electrodes and the ground terminal, and a second resistor is coupled between the plurality of second common electrodes and the ground terminal.

Preferably, both the first resistor and the second resistor are resistance values corresponding to the maximum value of the signal change ratio at the driving frequency of the touch screen. The signal change ratio

Preferably, the driving frequency of the touch screen is 10MHz-20MHz, the sum of the resistance of the plurality of first common electrodes and the resistance of the first resistance is 100-200 ohms, and the plurality of second common electrodes The sum of the resistance of the first resistor and the resistance of the second resistor is 100-200 ohms.

Further, the driving frequency of the touch screen is 10 MHz, the sum of the resistance of the plurality of first common electrodes and the resistance of the first resistance is 100 ohms, and the resistance of the plurality of second common electrodes and the resistance of the first resistance are 100 ohms. The sum of the resistance values of the second resistors is 100 ohms.

Preferably, the plurality of first common electrodes and the plurality of second common electrodes are arranged in strips at intervals.

Preferably, the common electrode layer is an ITO layer.

Preferably, the touch screen further includes a flexible circuit board, and the first resistor and the second resistor are arranged on the flexible circuit board.

Preferably, a touch chip is arranged on the flexible circuit board, the plurality of first common electrodes are connected in parallel to the touch chip through the first resistor, and the plurality of second common electrodes are connected in parallel Afterwards, it is connected with the touch control chip through the second resistor.

The present invention also provides a touch display device, including the above-mentioned touch screen, and the touch display device further includes: a second substrate disposed opposite to the touch screen; disposed between the touch screen and the second substrate a liquid crystal layer; the surface of the second substrate facing the liquid crystal layer is provided with a thin film transistor array layer.

Preferably, the insulating medium layer in the touch screen is a color filter film.

With the above-mentioned technical solution, the advantages and beneficial effects of the touch screen of the present invention are: the first resistor and the second resistor are respectively coupled between the driving ground, the sensing ground and the ground terminal of the embedded touch screen, and the optimization of the touch signal is realized. .

Description of drawings

The drawings illustrate the embodiments of the invention and, together with the description, serve to explain the principles of the invention. Through the following detailed description in conjunction with the accompanying drawings, you can more clearly understand the purpose, advantages and features of the present invention, wherein:

FIG. 1 is a schematic structural diagram of a touch display device in the prior art;

FIG. 2 is a schematic diagram of a single-layer capacitive touch structure in the prior art;

Fig. 3 is an equivalent circuit diagram of the intersection of the driving line and the sensing electrode in the prior art embedded touch screen;

4 is a schematic diagram of a common electrode layer structure including a driving ground and an inductive ground;

Fig. 5 is an equivalent circuit diagram of the intersection of the driving line and the sensing electrode in the in-cell touch screen including the common electrode layer shown in Fig. 4;

FIG. 6 is a schematic diagram of a common electrode layer grounded through a resistor in Embodiment 1 of the present invention;

Fig. 7 is an equivalent circuit at the intersection of the driving line and the sensing electrode in Embodiment 1 of the present invention;

Fig. 8 is a simulation diagram of the signal change ratio of the present invention;

FIG. 9 is a schematic structural diagram of an in-cell touch screen including a flexible circuit board according to Embodiment 2 of the present invention.

Detailed ways

In order to describe the technical contents and structural features of the present invention in detail, the following will be described in detail in conjunction with the embodiments and accompanying drawings.

As mentioned above, the in-cell touch screen 200 in the prior art touch display device (as shown in FIG. 1 ) includes a first substrate 26, a touch structure layer 21 formed on the first substrate 26 in sequence, an insulating medium layer 22 and a common electrode layer 23; the touch structure layer 21 can be a single-layer capacitive touch structure (as shown in Figure 2); the common electrode layer 23 includes a plurality of first common electrodes 24 and a plurality of second electrodes arranged in strips at intervals The common electrode 25 (as shown in FIG. 4 ). However, in the prior art, the resistance and inductance 19 of the first common electrode 24 and the resistance and inductance 20 of the second common electrode 25 will affect the detection signal, so that the detection signal cannot be optimized.

Example 1

In order to reduce the resistance and inductance 19 of the first common electrode 24 and the resistance and inductance 20 of the second common electrode 25 will affect the detection signal, optimize the detection signal; as shown in Figure 6, the first common electrode 23 of the present invention The common electrodes 24a, 24b, 24c, 24d of the electrode 24 are connected together in parallel, and then a first resistor 32 is coupled between the first common electrode 24 and the ground terminal; the common electrode 25a of the second common electrode 25 in the common electrode 23 , 25b, 25c, 25d are connected together in parallel, and then a second resistor 31 is coupled between the second common electrode 25 and the ground terminal.

After the first resistor and the second resistor are respectively coupled between the first common electrode 24, the second common electrode 25 and the ground terminal, the equivalent circuit at the intersection of the driving line 1 and the sensing electrode 2 of the in-cell touch screen 200 is shown in the figure 7. As shown in FIG. 7 , there is a coupling capacitor 30 between the first common electrode 24 and the second common electrode 25; there is also a resistor 16' and an inductor 17' at the actual ground terminal. Carry on simulation to the model established according to Fig. 7, its result is shown in Fig. 8.

The resistance and inductance 19 of the first common electrode 24, and the resistance and inductance 20 of the second common electrode 25 are set as fixed values; change the values of the first resistor 31 and the second resistor 32 and the frequency of the driving voltage 3 to obtain the detection signal 15 for a ratio of 35 changes.

The ratio 35 of the detection signal 15 change is calculated as:

The relationship between the sum Rdg of the resistances of the first resistor 31 and the first common electrode 24 (or the sum Rsg of the resistances of the second resistor 32 and the second common electrode 25 ) and the signal change ratio 35 is shown in FIG. 8 . It can be seen that the signal change ratio 35 has a maximum value as the sum Rdg of the resistances of the first resistor 31 and the first common electrode 24 (or the sum Rsg of the resistances of the second resistor 32 and the second common electrode 25 ) increases. Corresponding to different driving frequencies, the sum Rdg of the resistances of the first resistance 31 and the first common electrode 24 corresponding to this maximum value and the sum Rsg) of the resistances of the second resistance 32 and the second common electrode 25 are different, and the first resistance 31 and the size of the second resistor 32 are also different. The higher the frequency, the larger the resistance value to obtain the maximum touch signal. Because the frequency cannot be increased infinitely, high frequency will generate greater power consumption, and the high frequency effect will also reduce the signal, so the first resistor 31 and the second resistor 32 cannot be infinitely large. Therefore, we choose a more suitable frequency range, such as 10MHz-20MHz, and the corresponding resistance sum Rdg of a resistor 31 and the first common electrode 24 and the sum Rsg of the resistance of the second resistor 32 and the second common electrode 25 are 100 ohms to 200 ohms.

It can be seen from the simulation results shown in FIG. 8 that after additionally adding the first resistor 31 and the second resistor 32, the resistance values of the resistors 31 and 32 are determined according to the driving frequency. For example, when the driving frequency is 10 MHz, the first resistor 31 and the The sum Rdg of the resistances of the first common electrode 24 is 100 ohms, and the sum Rsg of the resistances of the second resistor 32 and the second common electrode 25 is 100 ohms. In this way, the touch signal can be maximized.

For a built-in touch screen that has been prepared, in order to select the first resistor 31 and the second resistor 32 of appropriate size, it is necessary to adjust the size of the first resistor 31 and the second resistor 32 under the driving frequency of the built-in touch screen Obtain the change curves of the signal change ratio 35 and the first resistor 31 and the second resistor 32, and select the first resistor 31 and the second resistor 32 corresponding to the maximum value of the signal change ratio 35.

Example 2

As a preferred embodiment, the in-cell touch screen of the present invention can arrange the first resistor 31 and the second resistor 32 on the flexible circuit board. As shown in FIG. 9 , the first common electrode 24 and the second common electrode 25 of the in-cell touch screen 37 are drawn out through a flexible circuit board 38 . The flexible circuit board 38 has a touch control chip 39 , and the first common electrode 24 and the second common electrode 25 are connected to the touch control chip 39 for grounding.

The structure of the in-cell touch screen 37 is the same as that of the in-cell touch screen 200 in FIG. The electrode layer 23; the touch structure layer 21 is a single-layer capacitive touch structure (as shown in Figure 2); the common electrode layer 23 includes a plurality of first common electrodes 24 and a plurality of second common electrodes 25 ( As shown in Figure 4).

The touch display device provided by the present invention includes the in-cell touch screen shown in FIG. 9 , and further includes a second substrate opposite to the in-cell touch screen; Liquid crystal layer; the surface of the second substrate facing the liquid crystal layer is provided with a thin film transistor array layer.

The above are only preferred embodiments of the present invention, and are not intended to limit the present invention. In the above-described embodiments, various modifications and changes are possible to the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (10)

1. A touch screen, comprising a first substrate, characterized in that the touch screen further comprises a touch structure layer, an insulating medium layer and a common electrode layer sequentially formed on the first substrate; The touch structure layer is a single-layer capacitive touch structure, including a plurality of driving electrodes and a plurality of sensing electrodes arranged at intervals in strips; The common electrode layer includes a plurality of first common electrodes facing the driving electrodes and a plurality of second common electrodes facing the sensing electrodes; A first resistor is coupled between the plurality of first common electrodes and the ground terminal, and a second resistor is coupled between the plurality of second common electrodes and the ground terminal. 2. The touch screen according to claim 1, wherein both the first resistor and the second resistor are resistance values corresponding to the maximum value of the signal change ratio at the driving frequency of the touch screen, so described 3. The touch screen according to claim 2, wherein the driving frequency of the touch screen is 10MHz-20MHz, and the sum of the resistance of the plurality of first common electrodes and the resistance of the first resistor is 100-20MHz. 200 ohms, the sum of the resistances of the plurality of second common electrodes and the resistance of the second resistor is 100-200 ohms. 4. The touch screen according to claim 3, wherein the driving frequency of the touch screen is 10 MHz, the sum of the resistances of the plurality of first common electrodes and the resistance value of the first resistance is 100 ohms, so The sum of the resistances of the plurality of second common electrodes and the resistance of the second resistor is 100 ohms. 5 . The touch screen according to claim 1 , wherein the plurality of first common electrodes and the plurality of second common electrodes are arranged in strips at intervals. 6. The touch screen according to claim 1, wherein the common electrode layer is an ITO layer. 7. The touch screen according to any one of claims 1-6, wherein the touch screen further comprises a flexible circuit board, and the first resistor and the second resistor are arranged on the flexible circuit board. 8. The touch screen according to claim 7, wherein a touch chip is arranged on the flexible circuit board, and the plurality of first common electrodes are connected in parallel to the touch chip through the first resistor. connected, the plurality of second common electrodes are connected in parallel and then connected to the touch control chip through the second resistor. 9. A touch display device, comprising the touch screen according to any one of claims 1-8, It is characterized in that the touch display device also includes: a second substrate disposed opposite to the touch screen; a liquid crystal layer disposed between the touch screen and the second substrate; The surface of the second substrate facing the liquid crystal layer is provided with a thin film transistor array layer. 10. The touch screen according to claim 9, wherein the insulating medium layer in the touch screen is a color filter film.