JPH0820927B2 - Matrix switch circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention relates to a matrix switch circuit in which a drive line and a sense line are made of a conductor having a relatively high resistance value.

[Prior Art] Conventionally, in a matrix switch circuit used for a transparent touch panel, as shown in FIG. 6 (A), a transparent conductive portion a formed by indium oxide or the like is used.
Is known as a sense line or a drive line, which is arranged in a lattice pattern (matrix pattern) on the film. The matrix switch circuit as the transparent touch panel has an excellent effect that it is attached to the screen of a CRT display device or the like and can be associated with the data on the screen.

[Problems to be Solved by the Invention] However, the transparent conductive portion a of the matrix switch circuit has a considerably low conductivity, and the following problems have been considered.

That is, as shown in FIG. 6 (B), the electric resistance value of the transparent conductive portion a increases as the distance from the conductive pattern portion b (hatched portion) increases, and zero [Ω] at point A and point B
Is R / 2 [Ω], and point C is R [Ω]. Moreover, since the actual circuit has a matrix structure, the maximum difference in electric resistance value is 2R [Ω]. Therefore, the smaller the conductivity is, the larger the difference between the resistance values becomes, and the phenomenon that the input signal input to the sensor or the like for detecting the touch position on the matrix switch varies and the erroneous detection may occur is considered. Therefore, the problem of lack of reliability was considered. This problem is more remarkable in a circuit having a larger substrate such as a touch panel.

If the resistance value of the matrix switch circuit is large, the resistance value of the pull-up resistor must also be increased to increase the potential amplitude of the sense line. The constant (so-called CR time constant) becomes large. Therefore, there is a problem that the potential of the sense line connected to the closed contact does not immediately recover even after the scanning of the closed contact (touch position) is finished, which causes a problem that the scanning speed is significantly limited. Was there.

In order to solve the above problems, inventions and proposals such as "matrix switch sense method" disclosed in Japanese Patent Laid-Open No. 59-216234 have been made, but each pull-up resistor has a switching element. It was thought that there was a problem that the control circuit had to be provided, and that the control circuit was complicated.

The matrix switch circuit of the present invention has been made for the purpose of solving the above problems, and has the following configuration.

Configuration of the Invention [Means for Solving the Problems] In the matrix switch circuit of the present invention, a drive line and a sense line are formed from a conductor having a relatively high resistance value, and the drive line and the sense line are arranged in a matrix. In the matrix switch circuit as described above, both ends of the sense line and / or the drive line are short-circuited.

[Operation] The matrix switch circuit of the present invention having the above structure operates as follows.

The matrix switch circuit of the present invention serves to detect the touch position by scanning and scanning the drive lines and the sense lines arranged in a matrix, but both ends of the sense line and / or the drive line are short-circuited. As a result, a circuit in which the short-circuited sense line and / or the drive line is touched becomes a circuit connected in parallel and the electric resistance value is reduced. As a result, the matrix switch circuit of the present invention functions to reduce the electric resistance value of the circuit and the time constant of the circuit including the sense line.

[Embodiment] Next, a preferred embodiment will be described with reference to the drawings in order to further clarify the configuration of the matrix switch circuit of the present invention.

As shown in FIG. 1, the matrix switch circuit of this embodiment is configured by arranging a plurality of drive lines x1 to xn and sense lines y1 to yn each having a predetermined width in a matrix. Drive lines x1 to xn or sense lines y1 to yn
Are formed by vapor-depositing a transparent low antibody (indium oxide in this example) on each polyester film substrate by a known method. Both ends of each of the drive lines x1 to xn are short-circuited by conductive patterns lx1 to lxn, and similarly, both ends of each of the sense lines y1 to yn are short-circuited by conductive patterns ly1 to lyn. It should be noted that one end of each of the conductive patterns lx1 to lxn is grounded via a multiplexer (not shown), and each end of the conductive patterns ly1 to lyn is pulled up to a predetermined potential E (V) via resistors R1 to Rn. In addition, the potential is detected via a multiplexer (not shown).

The matrix switch circuit having the above configuration is scan-scanned, for example, the drive line x1 is selected and connected to the ground side, and the sense line y2 and the pull-up resistor R2 are connected.
When a potential (hereinafter, simply referred to as a divided potential) Vsp between and is detected, its equivalent circuit can be represented as the circuit shown in FIG. 2 (A). Here, FIG. 2 (B) schematically shows the case where the point P1 shown in FIG. 1 is touched. This allows drive line x1 and sense line
y2 is a circuit in which the touched point P1 and both ends thereof are connected in parallel, and the schematic diagram shown in FIG. 2 (B) can be represented as an equivalent circuit shown in FIG. 2 (C). . The change state of the resistance value of the drive line x1 or the sense line y2 connected in parallel in the equivalent circuit shown in FIG. 2 (C) will be described with reference to FIGS. 3 (A) to (C).

If a point P shown in FIG. 3A (distance from the ground pattern side is x: 0 ≦ x ≦ l) is touched, the point P is shown as an equivalent circuit shown in FIG. 3B. Rx is 1 / [1 / x + 1 / (l−x)] = R / 4− (x−R / 2) ² / R where R is the distance of the point P. The resistance value in the case of.

Is represented as The value of the combined resistor Rx is shown as a graph in FIG. 3 (C). As can be seen from this graph, the combined resistor Rx has a small value of R / 4 or less. The straight line g1 in the figure shows the resistance value of the drive line or the sense line whose both ends are not short-circuited with respect to the distance x. Therefore, in the equivalent circuit shown in FIG. 2 (C), the combined resistor Rxy represented as a series connection of the drive line x1 and the sense line y2 connected in parallel has a small value of R / 2 or less (however, The sense line y2 has the same conductivity and length as the drive line x1).

Accordingly, when the point P1 or the like is touched, the value of the pull-up resistor R2 for setting the detected divided potential Vsp to be equal to or lower than the predetermined threshold level can be designed to be small. That is, the divided potential Vsp is equal to the predetermined voltage E
(V) is shown as a voltage divided by the pull-up resistor R2 and the combined resistor Rxy, but in the present embodiment, the combined resistor Rxy of the drive line x1 and the sense line y2 is set to a small value. As a result, the pull-up resistor R2 can also be made smaller.

Here, the block diagram shown in FIG. 4 shows an example of a matrix switch input detection device using the matrix switch circuit of this embodiment, and both ends of each drive line and sense line are selectively switched. Switch through circuit
Shorted by SW1 or SW2.

According to the matrix switch circuit of the present embodiment described in detail above, the combined resistance value of the drive line and the sense line having a relatively large resistance value is set to a small value and the resistance value of the pull-up resistor is also set to a small value with a simple configuration. can do. As a result, it is possible to reduce variations in the detected divided voltage potential and eliminate erroneous detection to improve its accuracy. Also, reduce the resistance value of the circuit to reduce the time constant and improve the scanning speed of scan scanning. It has an excellent effect that it can be made.

Here, the equivalent circuit shown in FIG. 5 (A) is the pull-up resistor R2 and drive line x1 of the conventional matrix switch circuit.
And the sense line y2 are shown in FIG. 5 (B).
Is a schematic diagram showing a state when the point P1 is touched in the equivalent circuit, and FIG. 5C shows an equivalent circuit at that time. As shown in the equivalent circuit of FIG. 5C, in the conventional matrix switch circuit, the combined resistor Rxy of the drive line x1 and the sense line y2 has a resistance value in a wide range from 0 to 2R. I know that it takes a value.

EFFECTS OF THE INVENTION According to the matrix switch circuit of the present invention, the drive line formed of a material having a relatively large resistance value and the possible resistance value of the sense or the like are set to a small value by the simple configuration, and the pull-up resistor for pull-up is used. The resistance value of the vessel can also be reduced. As a result, it is possible to reduce variations in the detected divided voltage potential and eliminate erroneous detection to improve its accuracy, and at the same time, reduce the resistance value of the circuit including the sense line to reduce the time constant and scan scanning. It has an excellent effect that the speed can be improved.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a matrix switch circuit according to an embodiment of the present invention, FIG. 2 (A) is an equivalent circuit diagram thereof, and FIGS. 2 (B) and (C) are states when a point P1 is touched. 3A and 3C are schematic diagrams and an equivalent circuit diagram, and FIGS. 3A to 3C show an explanatory diagram and an equivalent circuit diagram when the point P of the drive line x1 is touched, and a value of the combined resistor Rx. The graph shown in FIG. 4 is a circuit diagram showing an example of a matrix switch input detection device constructed by using the matrix switch circuit of the present invention, and FIG. 5 (A) is an equivalent circuit diagram of a conventional matrix switch circuit. (B) and (C) are schematic diagrams and an equivalent circuit diagram showing a state when the point P1 is touched, and FIGS. 6 (A) and (B) are explanatory diagrams showing a conventional matrix switch circuit and its driving. Indicates a line or sense line Akirazu, it is. x1,…, xn …… Drive line y1,…, yn …… Sense line lx1,…, lxn …… Conductive pattern ly1,…, lyn …… Conductive pattern R1,…, Rn …… Pull-up resistor

Claims (1)

[Claims] 1. A matrix switch circuit in which a drive line and a sense line are composed of a conductor having a relatively high resistance value, and the drive line and the sense line are arranged in a matrix, wherein the sense line and / or the drive line are provided. A matrix switch circuit characterized by shorting both ends of the wire.