CN102200867B - capacitive touch sensing device - Google Patents

Abstract

A capacitive touch sensing device comprises a plurality of driving lines, sensing lines and a detection circuit, wherein mutual capacitance is formed between the driving lines and the sensing lines, the detection circuit is used for detecting electric signals in the sensing lines, the sensing lines comprise first ends and second ends and extend along the direction from the first ends to the second ends, and the first ends and the second ends of the sensing lines are connected to the detection circuit together. The invention reduces the equivalent resistance of the induction line and improves the detection precision of the touch signal.

Description

capacitive touch sensing device

technical field

The invention relates to touch sensing technology, in particular to a capacitive touch sensing device.

Background technique

As a user interface for interactive operation, the touch screen includes resistive, capacitive, surface acoustic wave, infrared and so on. In the touch screen technology, compared with the resistive touch screen, the capacitive touch screen has the advantages of long life, high light transmittance, and can support multi-touch. It has a good suppression effect on noise and ground parasitic capacitance, and can realize multi-point Touch has therefore become a mainstream product in touch screens.

The structure of a capacitive touch sensing device is shown in Figure 1, Figure 2 and Figure 3, as shown in Figure 1, the structure of the capacitive touch sensing device shown in sequence from bottom to top includes: a driver formed on a glass substrate 9 An electrode layer 1, a dielectric layer 10, a sensing electrode layer 2 and a protective layer 11. Wherein, the driving electrode layer 1 and the sensing electrode layer 2 are working layers, and their pattern structures generally include diamond-shaped electrodes as shown in FIG. 2 and FIG. 3 , and the diamond-shaped electrodes of the two layers are interlaced with each other.

1 and 2, the driving electrode layer 1 is etched into a plurality of driving lines 5a, 5b, 5c, ..., 5h, and as shown in FIG. 1 and FIG. 3, the sensing electrode layer 2 is etched into a plurality of sensing lines 6a , 6b, 6c, ..., 6h, wherein the driving electrode layer 1 and the sensing electrode layer 2 are indium tin oxide (ITO) layers or indium zinc oxide (IZO) layers. 2 and 3, during operation, the drive lines 5a to 5h are sequentially applied with drive signals 3, usually tens of kilohertz (KHz) to hundreds of KHz of AC voltage, the rest of the drive lines are grounded, and the induction lines pass through the gate switch 17 is connected to a touch detection circuit 18 for detecting touch signals. For example, the driving line 5a is first scanned, that is, the driving signal 3 is applied to the driving line 5a, and the remaining driving lines 5b, 5c, ..., 5h are grounded 4. At this time, the gate switch 17 connects the sensing line 6a with the touch detection circuit 18 connected, that is, the detection is the driving line 5a and the sensing line 6a, when the finger touches the intersection of these two lines, the touch signal will be detected; then, the strobe switch 17 will turn the sensing lines 6b, 6c, ... , 6h are connected to the touch detection circuit 18 to detect the touch signals at the intersections of the driving line 5a and the sensing lines 6b, 6c, . . . , 6h respectively. After the scanning process of the driving line 5a is finished, the driving line 5b is scanned, that is, the driving line 5b is connected to the driving voltage 3, and the remaining driving lines 5a, 5c, ..., 5h are grounded 4, and the gate switch 17 sequentially connects the sensing lines 6a, 6b, 6c, . . . , 6h are connected to the touch detection circuit 18 . After scanning the driving lines 5a, 5b, 5c, .

The equivalent circuit at the intersection of each driving line and sensing line shown in Figure 2 and Figure 3 is shown in Figure 4: each intersection is equivalent to coupling a mutual capacitance 23, which is the opposite of the driving line and the sensing line The sum of the positive capacitance formed at the overlap and the fringe capacitance formed by the graphic edge on the driving line and the graphic edge on the sensing line; the resistor 22 is the equivalent resistance of the driving line, and the resistor 25 is the equivalent resistance of the sensing line; the driving line and The sensing lines respectively have parasitic capacitance 24 to ground; the excitation source 21 is used to generate the driving signal 3; the touch detection circuit 18 is an amplifier, which converts the electrical signal on the sensing line into a voltage signal Vout for output. When the finger touches, it can be understood that the finger builds a bridge between the driving line and the sensing line of the touch point, which is equivalent to connecting a capacitor in parallel on the mutual capacitance 23, so that the mutual capacitance 23 is equivalently increased, resulting in The electrical signal changes, thus changing the output voltage Vout.

In the equivalent circuit shown in FIG. 4 , the sensing line resistance 25 will affect the magnitude of the voltage signal Vout generated by the touch detection circuit 18. The smaller the resistance value of the resistance 25 is, the larger the obtained voltage signal Vout will be, and the corresponding touch signal will be larger. The larger the signal-to-noise ratio, the higher the detection accuracy of the touch signal. Although increasing the line width and film thickness of the sensing line can reduce the resistance, increasing the line width will also increase the parasitic capacitance and affect the signal-to-noise ratio; increasing the film thickness is limited by the technological level. The Chinese patent application with the application number 200710180736.1 discloses a capacitive touch panel with a low impedance structure. The sensing line is divided into two parts, and the equivalent resistance of each part is smaller than the resistance of the entire sensing line before cutting. In this way, the equivalent resistance of the sensing line is reduced. However, there is a gap at the cutout of the sensing line in this solution, and when the touch panel is used for a touch display, it will affect the uniformity of display brightness.

The prior art also includes another capacitive touch sensing device, its structure is shown in Figure 5, which is a single-layer structure, the driving lines and sensing lines are all in the same working layer, and the driving electrodes 20a, 20b, 20c, 20d, 20e , 20f and the mutual capacitance formed between the sensing lines 21a, 21b, 21c form a matrix structure. Specifically, the driving electrodes 20a, 20b, 20c, 20d, 20e, and 20f are arranged in a matrix, and the sensing lines 21a, 21b, and 21c are arranged between two rows of driving electrodes; They are respectively connected together in the peripheral area to form a driving line; one end of the sensing lines 21a, 21b, 21c is connected to the detection circuit 21 in the peripheral area. Wherein, each driving electrode and the sensing electrode form a mutual capacitance, and the equivalent circuit between each driving electrode and the sensing electrode shown in FIG. 5 is also shown in FIG. 4 . The touch sensing device shown in FIG. 5 also has the problem that the equivalent resistance of the sensing line is relatively large, which affects the detection accuracy of the touch signal.

Contents of the invention

The problem solved by the present invention is to provide a capacitive touch sensing device to reduce the equivalent resistance of the sensing line and improve the detection accuracy of touch signals.

In order to solve the above problems, the present invention provides a capacitive touch sensing device, which includes a plurality of driving lines, sensing lines and detection circuits, mutual capacitance is formed between the driving lines and sensing lines, and the detection circuit is used to detect the sensing lines The electrical signal in the induction line includes a first end and a second end and extends along the direction from the first end to the second end, and the first end and the second end of the induction line are commonly connected to the detection circuit .

Optionally, the extending direction of the driving lines and the extending direction of the sensing lines are perpendicular to each other.

Optionally, the driving lines and the sensing lines are respectively formed in the driving electrode layer and the sensing electrode layer, and a dielectric layer is formed between the driving electrode layer and the sensing electrode layer.

Optionally, the driving line includes a plurality of first patterns and a first connecting portion connecting the first patterns, and the sensing line includes a plurality of second patterns and a second connecting portion connecting the second patterns, The second connecting portion and the first connecting portion overlap each other, and the second pattern and the first pattern are staggered from each other.

Optionally, the dielectric layer includes a first dielectric layer, a second dielectric layer, and a shielding layer located between the first dielectric layer and the second dielectric layer.

Optionally, the driving lines and the sensing lines are formed on the same electrode layer.

Optionally, the driving line includes a plurality of driving electrodes, and the driving electrodes of the plurality of driving lines are arranged in a matrix, and the sensing line is arranged between two rows of driving electrodes.

Optionally, the driving electrodes in the same driving line are electrically connected to each other.

Optionally, shielding lines are formed between the driving electrodes and the sensing lines.

Optionally, the first end and the second end of the sensing line are connected to the detection circuit through a printed circuit board or a flexible circuit board.

Compared with the prior art, the above-mentioned technical solution has the following advantages:

The technical solution of the present invention connects the first end and the second end of the sensing line to the detection circuit, so that the touch signal can be transmitted to the detection circuit through the shortest path, thereby reducing the equivalent resistance of the sensing line and improving the touch signal. Detection accuracy.

Description of drawings

1 is a schematic cross-sectional structure diagram of a capacitive touch sensing device in the prior art;

2 and 3 are structural schematic diagrams of the driving lines and the sensing lines in the structure shown in FIG. 1;

4 is a schematic diagram of an equivalent circuit at the intersection of the driving line and the sensing line of the capacitive touch sensing device;

FIG. 5 is a structural schematic diagram of driving lines and sensing lines of another capacitive touch sensing device in the prior art;

6 is a schematic cross-sectional structure diagram of a capacitive touch sensing device according to an embodiment of the present invention;

FIG. 7 and FIG. 8 are partial structural schematic diagrams of the driving line and the sensing line in the structure shown in FIG. 6;

Fig. 9 is a schematic diagram of the connection structure between the induction line and the detection circuit in the structure shown in Fig. 6;

FIG. 10 is a schematic structural diagram of driving lines and sensing lines of another capacitive touch sensing device according to an embodiment of the present invention;

FIG. 11 is a schematic structural diagram of driving lines and sensing lines of another capacitive touch sensing device according to an embodiment of the present invention.

detailed description

In order to make the above objects, features and advantages of the present invention more comprehensible, specific implementations of the present invention will be described in detail below in conjunction with the accompanying drawings.

In the following description, specific details are set forth in order to provide a thorough understanding of the present invention. However, the present invention can be implemented in many other ways than those described here, and those skilled in the art can make similar extensions without departing from the connotation of the present invention. Accordingly, the present invention is not limited to the specific embodiments disclosed below.

In a capacitive touch sensing device, the equivalent resistance of the sensing line will affect the magnitude of the electrical signal transmitted to the detection circuit, thereby affecting the signal-to-noise ratio of the signal received by the detection circuit, thus affecting the detection accuracy of the touch signal. As the area of the touch display screen using the capacitive touch technology becomes larger and larger, the length of the sensing line is correspondingly longer, resulting in a larger equivalent resistance, which affects the detection accuracy of the touch signal. In the prior art, the sensing line is divided into two parts, and the two parts are respectively connected to the detection circuit, thereby reducing the independent equivalent resistance of each part of the sensing line. However, the gap formed after the sensing line is cut in this solution will affect the brightness uniformity of the touch display screen.

After research, the inventor found that in the prior art, only one end of the sensing line is connected to the detection circuit. As the length of the sensing line increases with the area of the touch screen, the equivalent resistance of the sensing line increases. The situation is that one end of the sensing line detects a touch signal, but the corresponding electrical signal needs to flow through the entire sensing line to be transmitted to the detection circuit at the opposite end of the sensing line for detection, so that the equivalent circuit shown in Figure 4 The resistance value of the sensing line resistance 25 is too large, which seriously affects the detection accuracy of the touch signal. The technical solution of the present invention connects both ends of the sensing line to the detection circuit, and the touch signal can be transmitted to the detection circuit through the shortest path (that is, through the end relatively close to the detection circuit), thereby reducing the equivalent of the sensing line. The resistor improves the detection accuracy of the touch signal.

FIG. 6 shows a schematic cross-sectional structure diagram of a capacitive touch sensing device according to an embodiment of the present invention. As shown in FIG. 32, the sensing electrode layer 33 and the protection layer 34. Wherein the driving electrode layer 31 and the sensing electrode layer 33 may be an ITO layer or an IZO layer; the dielectric layer 32 is a transparent dielectric layer.

In other embodiments of the present invention, the dielectric layer 32 can also be a composite multi-layer structure, including a first dielectric layer, a second dielectric layer and a shielding layer between the first dielectric layer and the second dielectric layer ( not shown in the figure). The first dielectric layer and the second dielectric layer are transparent dielectric layers, and the shielding layer can be an ITO layer or an IZO layer, which are used to reduce the driving electrodes and sensing electrodes in the driving electrode layer 31 and the sensing electrode layer 33. The mutual capacitance between them improves the touch signal detection accuracy.

Specifically, as shown in FIG. 7, a plurality of parallel driving lines (vertical direction in FIG. 7) are formed in the driving electrode layer 31, and the driving lines include a plurality of first patterns 31a and connecting the The first connecting portion 31b of the first figure 31a, the shape of the first figure 31a in this embodiment is a rhombus, and in other embodiments of the present invention can also be other polygons, such as a rectangle or a hexagon.

Specifically, as shown in FIG. 8 , a plurality of sensing lines (horizontal direction in FIG. 8 ) perpendicular to the driving lines are formed in the sensing electrode layer 32 , and the sensing lines are parallel to each other. The induction line includes a plurality of second graphics 32a and a second connecting portion 32b connecting the second graphics 32a. In this embodiment, the shape of the second graphics 32a is a rhombus. In other embodiments of the present invention, it is also Can be other polygons, such as rectangle or hexagon, etc. The second graphic 32a is staggered from the first graphic 31a, and the second connecting portion 32b is facing and overlapping the first connecting portion 31b.

Fig. 9 shows the connection structure of the sensing line and the detection circuit in this embodiment. As shown in Fig. 9, a plurality of sensing lines 8a, 8b, ..., 8h respectively include a first end and a second end, wherein each sensing line Extending along the direction from the first end to the second end, the first end and the second end are commonly connected to a detection circuit 35, wherein the detection circuit 35 includes a gate switch 35a and a touch detection circuit 35b. In a specific embodiment, the first end and the second end can be connected to the detection circuit 35 through a printed circuit board (PCB) or a flexible circuit board (FPC), that is, the wiring is routed in the peripheral area of the sensing line and connected to the PCB or FPC, and the first terminal and the second terminal are connected to the detection circuit 35 on the PCB or FPC.

In the specific touch signal detection process, a certain driving line is first scanned, and the gate switch 35a connects the first end and the second end of the sensing line 8a to the touch detection circuit 35b, that is, the driving line and the sensing line 8a are detected. Whether it is touched at the intersection; Afterwards, the strobe switch 35b once again connects the sensing lines 8b, 8c, ..., 8h to the touch detection circuit 35b, and respectively detects the driving lines and the sensing lines 8b, 8c, ..., The touch signal at the intersection of 8h, after the detection is completed, the above detection process is performed on the next driving line, so as to complete whether there is a touch action at the intersection of all driving lines and sensing lines.

Since the two ends (the first end and the second end) of the sensing line are commonly connected to the detection circuit 35 in the technical solution of this implementation, when there is a touch action, the corresponding electrical signal can be transmitted to the detection circuit 35 through the shortest path . The worst case is that there is a touch action at the midpoint of the sensing line, and the length of the transmission path of the corresponding electrical signal is half of the length of the sensing line, thus effectively reducing the equivalent resistance of the sensing line and improving the sensitivity of the touch signal. Detection accuracy. Moreover, compared with the technical solution mentioned in the background art, the sensing line of the present technical solution does not have a gap caused by cutting the sensing line, which will not affect the brightness uniformity of the touch display screen.

FIG. 10 shows a schematic structural diagram of driving lines and sensing lines of another capacitive touch sensing device according to an embodiment of the present invention. In this structure, the sensing lines and driving lines are formed in the same electrode layer. As shown in FIG. 10 , it includes drive lines 36a, 36b, ... , 36f, and induction lines 37a, 37b, 37c, wherein the drive lines include a plurality of drive electrodes. The shape of the drive electrodes in this embodiment is rectangular and is located at The driving electrodes in the same driving line are electrically connected to each other. Wherein, the driving electrodes of the plurality of driving lines are arranged in a matrix, and the sensing lines are arranged between two rows of driving electrodes. The touch signal detection process of the capacitive touch sensing device in this embodiment is similar to the above embodiment, and will not be repeated here. Since the first end and the second end of the sensing line in this technical solution are commonly connected to the detection circuit 37 , the equivalent resistance of the sensing line is small, which improves the detection accuracy of the touch signal.

It should be noted that in this embodiment, the driving lines are arranged in a vertical direction, and the induction lines are arranged in a horizontal direction. In the embodiment of the present invention, the driving lines can also be arranged in a horizontal direction, while the induction lines are arranged in a vertical direction In this case, the sensing line is arranged between two columns of driving electrodes. In addition, the driving lines and the sensing lines can also be arranged in other directions on the premise that they are perpendicular to each other.

FIG. 11 shows a schematic structural diagram of driving lines and sensing lines of another capacitive touch sensing device according to an embodiment of the present invention. The structure is basically the same as that shown in FIG. 10 , including a plurality of driving lines 38a, 38b, ..., 38f and a plurality of sensing lines 39a, 39b, 39c, the difference is that a plurality of shielding lines 40 are also included between the driving electrodes and the sensing lines of each row, so as to reduce the mutual capacitance between the driving lines and the sensing lines , improving the detection accuracy of the touch signal. Similar to the capacitive touch sensing device shown in FIG. 10 , both ends of the sensing line are commonly connected to the detection circuit 39 . In addition, similar to the structure in FIG. 9 , the sensing lines of the capacitive touch sensing devices shown in FIG. 10 and FIG. 11 can also connect both ends to the detection circuit through PCB or FPC.

It should be noted that the arrangement directions and numbers of the driving lines and the sensing lines shown in FIG. 9 , FIG. 10 and FIG. 11 are only examples, and can be adjusted according to requirements in practical applications. In addition, the capacitive touch sensing device described in the above embodiments can be used alone in a specific application, as a detection device for a touch action, or can be combined with a liquid crystal display panel (LCD), as a touch screen to perform a corresponding response according to a touch action. processing and display.

In summary, the capacitive touch sensing device in the technical solution of the present invention connects both ends of the sensing line to the detection circuit, thereby effectively reducing the equivalent resistance of the sensing line and improving the detection accuracy of the touch signal. At the same time, compared with the prior art, there is no gap caused by cutting the sensing line in this technical solution, which will not affect the uniformity of display brightness.

Although the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention, and any person skilled in the art can use the methods disclosed above and technical content to analyze the present invention without departing from the spirit and scope of the present invention. Possible changes and modifications are made in the technical solution. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention, which do not depart from the content of the technical solution of the present invention, all belong to the technical solution of the present invention. protected range.

Claims (5)

1. A capacitive touch sensing device, comprising a plurality of driving lines, sensing lines and detection circuits, mutual capacitance is formed between the driving lines and the sensing lines, and the detection circuit is used to detect electrical signals in the sensing lines, so The induction line includes a first end and a second end and extends along the direction from the first end to the second end, wherein the first end and the second end of the induction line are commonly connected to the detection circuit; Wherein, the first end and the second end of the sensing line are commonly connected to the detection circuit, including: After the first end and the second end of the induction line are connected, one end is drawn out and connected to the detection circuit; The driving line and the sensing line are respectively formed in the driving electrode layer and the sensing electrode layer, and a dielectric layer is formed between the driving electrode layer and the sensing electrode layer; The dielectric layer includes a first dielectric layer, a second dielectric layer and a shielding layer between the first dielectric layer and the second dielectric layer. 2 . The capacitive touch sensing device according to claim 1 , wherein the extending direction of the driving lines and the extending direction of the sensing lines are perpendicular to each other. 3. The capacitive touch sensing device according to claim 1, wherein the driving line comprises a plurality of first patterns and a first connecting portion connecting the first patterns, and the sensing line comprises a plurality of first patterns. The second figure and the second connection part connecting the second figure, the second connection part and the first connection part overlap each other, and the second figure and the first figure are staggered. 4. A capacitive touch sensing device, comprising a plurality of driving lines, sensing lines and detection circuits, mutual capacitance is formed between the driving lines and sensing lines, and the detection circuit is used to detect electrical signals in the sensing lines, so The induction line includes a first end and a second end and extends along the direction from the first end to the second end, wherein the first end and the second end of the induction line are commonly connected to the detection circuit; Wherein, the first end and the second end of the sensing line are commonly connected to the detection circuit, including: After the first end and the second end of the induction line are connected, one end is drawn out and connected to the detection circuit; The driving lines and the sensing lines are formed on the same electrode layer; the driving lines include a plurality of driving electrodes and the driving electrodes of the driving lines are arranged in a matrix, and the sensing lines are arranged between two rows of driving electrodes; The driving electrodes in the same driving line are electrically connected to each other; A shielding line is formed between the driving electrode and the sensing line. 5. The capacitive touch sensing device according to any one of claims 1 to 4, wherein the first end and the second end of the sensing line are connected to the detection device through a printed circuit board or a flexible circuit board. circuit.