JPH0131251B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a transparent capacitively coupled display device that is mounted on a display panel of an electro-optical display device (CRT, PDP, EL, etc.) and used to select a desired item from information displayed on a light-emitting display. Regarding matrix switches.

Conventional capacitively coupled matrix switches of this type, such as transparent switches (simply referred to as switches)
The structure and operation of the device will be explained with reference to the sectional view of FIG.

The switch is made by depositing transparent electrodes, such as vapor-deposited thin films of tin oxide or indium oxide, on both the front and back surfaces of a transparent dielectric substrate 1 made of glass or plastic, forming capacitance electrodes 2 and 3, which are used as switch poles. It is something. When the switch is placed on the panel surface of the display device or attached to the front surface of the panel, the switch is configured so that the numbers, characters, etc. displayed on the panel can be seen through it.

A transparent dielectric protection layer 4 is provided above the switch pole 2, and a similar transparent insulating protection layer 5 is provided below the other pole 3.

A matrix switch in which switches with such a configuration are arranged in a matrix is placed on the display panel 6, and by operating the switch corresponding to a desired item among the many display items on the display panel surface with finger pressure, the capacitance between the switch poles can be increased. Changes during this time can be detected and display items can be selected.

However, in such a conventional capacitance variable switch, the electrodes 2 and 3 are formed overlappingly on the switch shaft 7, so that when the switch is operated, the signal input source side (electrode 2 side) and the signal detection circuit side (Electrode 3
As a result, the transfer cut-off ratio (output ratio when the switch is ON and when the switch is OFF) as a switch performance index is small, and the noise from the display panel surface cannot be blocked. Improvements were needed from the front.

An object of the present invention is to eliminate the above-mentioned problems, and to provide the following switch configuration with a high switch performance index.

The capacitively coupled matrix switch according to the present invention is characterized by having a first electrode as a common electrode connected to ground on one entire surface of the transparent dielectric substrate, and a first electrode as a common electrode connected to the ground on the other surface of the substrate. A third electrode is connected in a circuit pattern in the Y column direction to the switch position corresponding to the intersection of the X and Y matrices.
Second electrodes are connected to the electrodes in a circuit pattern in the X direction at the matrix switch position through another transparent dielectric substrate, and the second electrodes and the third electrodes are located so as not to overlap. A transparent dielectric protective layer is further provided on the second electrode, and each electrode is made of a transparent electrode. In order to create a large capacitance between the second electrode and the third electrode when the switch position where the electrodes do not overlap with each other is pressed down with a finger, Also, the first electrode, the second electrode, and the third electrode are arranged so as to constitute a capacitance electrode.

Embodiments of the switch of the present invention shown in FIGS. 2 to 4 will be explained below. FIG. 5 shows the electrical equivalent circuit of this switch.

In the embodiment shown in FIG. 2, A is a top view of the switch, and B is a sectional view taken along line A-A' of A.

In the figure, a transparent second electrode 2 and a transparent third electrode 3 are shown, which are formed by vapor-depositing indium oxide (In ₂ O ₃ ) or the like on both the front and back surfaces of a transparent dielectric substrate 1 such as glass. However, the transparent electrodes 2 and 3 are offset from each other with respect to the switch axis 7 shown in the figure, which is the switch pressing position, and the electrode surfaces do not overlap, for example, if electrode 2 is on the left, electrode 3 is on the right. It is in the form of an electrode pattern that forms a capacitance electrode at a related position. The electrode pattern is shown in Figure A.

Also, a transparent dielectric substrate 5 below the transparent dielectric substrate 1
A transparent first electrode 8 to which In ₂ O ₃ or the like is connected to the earth in the same manner as described above is provided on the lower surface of the electrode, and serves as a counter electrode for the second electrode 2 and the third electrode 3. .

This capacitive coupling type matrix switch is constructed by laminating the transparent dielectric substrate 1 and the transparent dielectric substrate 5 manufactured by the above method as shown in the figure. However, a transparent dielectric insulating layer 4 made of polyester or the like is added to the switch surface, which forms a switch pressing surface and also has the function of protecting the electrode 2 from external mechanical scratches.

FIG. 3 shows another embodiment of the invention.

That is, in the capacitively coupled matrix switch shown in FIG. 3, the transparent second electrode 2 is deposited on the lower surface of the transparent dielectric insulating layer 1', and the transparent third electrode 3 is deposited on the lower surface of the transparent dielectric substrate 1''. Further, a transparent first electrode 8 is laminated and bonded to a transparent dielectric substrate 5 provided on the lower surface as shown in the figure.

According to the arrangement of FIG. 3, the upper surface of the transparent dielectric insulation layer 1', on which the second electrode 2 is deposited, forms the switch pressing surface and constitutes a mechanical scratch protection layer.

FIG. 4 shows yet another embodiment, in which the transparent second electrode 2 and the transparent third electrode are arranged in a non-overlapping relationship. Figure A is a top view of the switch.
B is a sectional view taken along line A-A' in FIG.

The transparent second electrode is formed in a comb-like pattern on the surface of the transparent dielectric substrate 1, and the transparent third electrode 3 is formed on the back side of the transparent dielectric substrate 1, but the shapes of these electrodes 2 and 3 are as follows. As is clear from Figure A, the arrangement is such that there are no opposing areas that are offset from each other.

The laminated structure of the transparent dielectric substrate 5 and the transparent dielectric substrate 1 having the transparent first electrode 8 provided on the lower surface is the same as that shown in FIG. 2.

Note that 9 in the figure is a location where the circuit patterns of the second and third electrodes intersect via the substrate 1.

The electrical functions of the switches of the present invention shown in FIGS. 2 to 4 will be explained using the equivalent circuit shown in FIG. Numbers 2, 3 and 8 in the figure correspond to the aforementioned electrodes.

This switch has a ground 13 that blocks noise coming from the display panel surface; a transparent first electrode 8 that also serves as a conductor surface;
and different distances D ₃ and D ₂ (D ₃ corresponds to the thickness of the transparent dielectric substrate 5, and D ₂ corresponds to the thickness of the transparent dielectric substrate 5 and the transparent dielectric substrate 1. See FIG. 2) A transparent third electrode 3 and a transparent second electrode 2 are provided, and a capacitance is formed between the first electrode and the second electrode, and between the first electrode and the third electrode, while a capacitance is formed between the second electrode and the third electrode. The capacitance (10 shown in the figure) is minute.

On the other hand, the high frequency signal source 11 that drives this switch
is connected between the first electrode 8 and the second electrode 2, and a detection circuit 12 for detecting a switch operation is connected between the first electrode 8 and the third electrode 3. However, Figure 2~
When a finger touches the switch shown in FIG. 4, an illustrated coupling capacitance 10 between two capacitances is generated.
Along with this, the high frequency signal source 11 is switched and a large signal output is transmitted to the right detection circuit 12. In this way, a switch function is provided in which the output level changes significantly depending on the presence or absence of acupressure.

Figure 6 is a switch performance comparison graph, showing the transmission/cutoff ratio between this switch A and the conventional switch B.
This is a comparison of switch performance in terms of (ON/OFF ratio).

It is clear from the figure that this switch has significantly superior performance. The reason for this is that, as mentioned above, by adopting a laminated structure of electrodes that are unevenly distributed and do not overlap each other on the transparent first electrode 8 (conductive layer of the ground 13), the mutual coupling capacitance during cutoff (when OFF) is reduced. This is because it is considered small.

That is, according to the present invention, since the first electrode 8 is coated on the entire surface and connected to the ground, it is possible not only to block noise signals from the display panel surface, but also to block the second electrode 8.
The positions of the third electrodes are shifted from each other so that they do not overlap, and the positions are arranged so that when the switch position is pressed with a finger, the capacitance between the second and third electrodes becomes large. As the switch surface is made of a dielectric insulating layer, it can withstand mechanical scratches, and even when pressed with a finger, it does not come into direct contact with the high-frequency signal, and each Since the electrodes, substrate, etc. are all made of transparent materials, even when placed on the surface of the display panel, it is easy to see the display on the display panel and press the switch position corresponding to the required location.

FIGS. 7 and 8 show general views of a capacitively coupled matrix switch in which the switches of the present invention are arrayed in a grid array on the panel surface of an electro-optical display device. In the illustrated example, the devices are arranged in three rows each vertically and horizontally. Fig. 7 shows a matrix switch using the electrode shape pattern shown in Fig. 2, and Fig. 8 shows a matrix switch using the electrode shape pattern shown in Fig. 4. Fig. A is a perspective view, and Fig. A is a top view of the switch unit. It is.

A transparent first electrode 8 is deposited on the entire bottom surface of the matrix switch and connected to earth. Further, the transparent second electrode 2 is connected to a circuit pattern 14 for connecting X rows (horizontal rows). The other transparent third electrode 3
is circuit pattern 15 for Y column (vertical) connection
(circuit shown by dotted line).

However, at the intersections of the circuit patterns in the X and Y columns, in order to avoid the generation of capacitance that would reduce the change in coupling capacitance during switch ON and OFF operations, the circuit pattern intersections shown in the top view of Figure B are used. In section 9, a notch 16 is provided to reduce the opposing area and reduce the capacitance (commonly known as stray capacitance) between the circuit patterns.
is considered small.

Note that the circuit pattern 14 connected in the X column and the circuit pattern 15 connected in the Y column can be formed at the same time when the transparent second electrode and the transparent third electrode 3 are deposited.

The matrix switches in such an arrangement are operated by a gate circuit and an encoder circuit (not shown) in a switch detection circuit (12 in FIG. 5) which is connected to the circuit pattern 15 side when any switch in the plane is finger pressed. The shiatsu switch will be detected.

The capacitive coupling type matrix switch of the present invention has the following features: a high switch transmission cutoff ratio, a simple signal detection circuit related to this, a noise signal from the display panel surface being blocked, and a finger press. The reliability of the switch is also improved because it is located on the dielectric surface rather than directly on the electrode surface, so it does not come into direct contact with high-frequency signals, and has greater mechanical scratch resistance. From this point of view, this switch is expected to have a wide range of applications, and its industrial effects will be significant.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a conventional switch configuration, FIGS. 2 to 4 are top views and sectional views showing embodiments of the switch configuration of the present invention, and FIG. 5 is an equivalent circuit of the switch shown in FIGS. 2 to 4. 6 is a switch performance comparison graph, and FIGS. 7 and 8 are perspective views of an embodiment as an overall view of the capacitive coupling type matrix switch according to the present invention. In the figure, 1, 1'', 5 are transparent dielectric substrates, 1', 4
is a transparent dielectric protective layer, 2 is a transparent second electrode, 3 is a transparent third electrode, 7 is a switch axis, 8 is a transparent first electrode, 9 is a circuit pattern intersection, 10 is a coupling capacitance, and 14 is X Reference numeral 15 indicates a circuit pattern of column connection, 15 indicates a circuit pattern of Y column connection, and 16 indicates a notch.

Claims (1)

[Claims] 1. A first electrode as a common electrode connected to ground is provided on one entire surface of the transparent dielectric substrate, and switches are provided on the other surface of the substrate in the Y column direction at switch positions corresponding to the intersections of the X and Y matrices. a third electrode coupled with a circuit pattern; and a second electrode coupled with a circuit pattern in the X direction at the matrix switch position via another transparent dielectric substrate, and a second electrode coupled with the circuit pattern in the X direction, respectively; The second electrode and the third electrode are shifted in position so as not to overlap, and form a switch as a pair, and a transparent dielectric protective layer is further provided on the second electrode, and each electrode is made of a transparent electrode. Moreover, when a switch position on the dielectric protective layer where the second electrode and the third electrode do not overlap is pressed down with a finger, a large capacitance is formed between the second electrode and the third electrode.
In addition, the first electrode and the second electrode, and the first electrode and the third electrode also constitute a capacitance electrode.
A capacitive coupling type matrix switch characterized in that a third electrode is arranged.