JPH0629801B2 - Keystroke sensor- - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to a keying force sensor, and in particular, it has a novel structure, small variations in load and output voltage characteristics, excellent reproducibility, and reduced thickness. The present invention relates to a keying force sensor that can be integrated and has excellent mass productivity.

[Technical Background of the Invention] Various switches using a pressure-sensitive conductive rubber sheet as an input element are widely used for electronic parts. An example of an input switch using a pressure-sensitive conductive rubber sheet is generally ON-OFF.
In addition to switches, input elements of handwriting input position detection devices and the like are known.

Further, by applying the pressure-sensitive sensor property of pressure-sensitive conductive rubber, for electronic organ using a pressure-sensitive conductive rubber sheet (JP-A-53-79937 and JP-A-54-80350) The keystroke sensor has been put to practical use. This is a structure in which a ribbon of a pressure-sensitive conductive rubber sheet sandwiched between metal sheets for electrodes is placed in a shallow groove provided in a polyvinyl chloride resin extruded material and covered with a felt from above. After making a sound by pressing the keyboard, further pressure is applied to the keyboard to cause a resistance change of the sensor, which is signaled as a signal between terminals by a constant current and output as a specified control signal by an operational amplifier, and volume, tone color Alternatively, it controls the pitch.

However, the method using this pressure-sensitive conductive rubber sheet has the drawback that the load and output voltage characteristics vary and the reproducibility is not good, so it can only be used as a very inaccurate keystroke sensor. It has not been. Furthermore, when manufacturing this keying force sensor, an extremely long ribbon-shaped sheet is required, and the current molding method has the drawbacks of poor mass productivity, difficulty in setting with electrodes, and high cost. There is.

[Object of the Invention] The present invention has been made in order to solve the above-mentioned drawbacks, and has a novel structure, small variation in load and output voltage characteristics, excellent reproducibility, thinness, and integrated structure. It is intended to provide a keystroke force sensor that can be made into a product and is excellent in mass productivity.

[Structure of the Invention] That is, the present invention relates to an electric circuit which is formed on a first electrically insulating substrate and covered with a carbon electrode,
An electric circuit which is formed on a second electrically insulating substrate and which is covered with a carbon electrode and is arranged with a gap from the electric circuit of the first substrate; A keystroke force sensor, comprising a pressure-sensitive conductive layer deposited on at least one side of the pressure-sensitive conductive layer.

The electrically insulating substrate used in the present invention may be plate-shaped or film-shaped, and may be hard or flexible. Examples thereof include a phenol resin, an epoxy resin, a polyester resin, a silicone resin, a polyimide resin, a film of natural or synthetic rubber, a laminated product, a molded product, and the like. The thickness is suitably 0.015 mm to 2 mm, particularly preferably 0.1 to 0.5 mm. If it is less than 0.015 mm, screen printing is difficult and the strength is weak. If it exceeds 2 mm, moldability is poor and the cost is high.

Further, the electric circuit configured on the substrate is a method of attaching a conductive metal foil to the substrate and then etching, a method of forming a conductive metal by vapor deposition, and a screen printing of a conductive paste such as silver. Although it is formed by a forming method or the like, the screen printing method is suitable for accurately and economically forming a long ribbon-shaped pattern. Further, screen printing of a carbon paste is also suitable for covering the above-mentioned electric circuit with a carbon electrode.

Next, the pressure-sensitive conductive layer deposited on the circuit is preferably made of silicone rubber in which one or more kinds of metal particles such as silver, copper and nickel and carbon black are dispersed. In particular, when metal powder such as nickel powder used in JP-A-59-98164 is surface-treated with a platinum compound as the metal powder, variation in load and output voltage characteristics is small and reproducibility thereof is small. It is preferable because it is excellent. In addition, since this composition can have adhesiveness to a substrate and can be directly applied to an electrode by a method such as screen printing, it has a very long ribbon-like shape which is a drawback of the prior art. Can be easily molded,
It is possible to integrate them.

The thickness of the pressure-sensitive conductive layer is 10 μm or more from the viewpoint of pressure-sensitive conductivity.
Less than μm is suitable, preferably 25 μm to 50 μm. If it is less than 10 μm, the initial insulation is difficult to obtain, and 80 μm
When it is m or more, the output voltage is too low and the variation becomes large.

Further, it is preferable that the first and second electrically insulating substrates are bonded together by placing the electric circuit and the pressure-sensitive conductive layer in the middle so that they can be easily set on the mounting plate of the electronic organ. As a method of laminating, any method such as a method of forming an adhesive by screen printing and laminating, a method of laminating with a double-sided adhesive tape, a method of laminating with various other adhesives, etc. may be used. A suitable method is to form an adhesive and then bond them together.

Further, a felt may be attached to the keying force sensor to be integrated, or a double-sided adhesive tape may be attached to the lower part of the keying force sensor so as to be easily set on a mounting plate of an electronic organ.

As described above, the keystroke force sensor for an electronic organ is provided by combining the constituent elements according to the present invention.

[Examples of the Invention] The present invention will be described in detail below with reference to examples, but the present invention is not limited to the examples as long as the gist of the present invention is not impaired. In the reference examples, all parts are parts by weight.

Reference Example 1 (Production of Platinum Compound Treated Conductive Metal Powder) 100 parts of vinyl siloxane coordinated platinum complex 1% by weight xylene solution was added to 100 parts of nickel particles having an average particle size of 3 to 7 μm obtained from nickel carbonyl. Was stirred, heated and refluxed. After 4 hours, the complex-treated powder was separated by filtration, washed, and heated at 150 ° C. for 2 hours to obtain platinum-siloxane complex-treated nickel particles.

Reference Example 2 (Production of pressure-sensitive conductive silicone rubber paste) Addition type silicone rubber [TSE manufactured by Toshiba Silicone Co., Ltd.]
3221] To 100 parts, 300 parts of the platinum-siloxane complex-treated nickel particles of Reference Example 1 and 6 parts of acetylene black were premixed with a small blender and dispersed by a three-roll mill to prepare a pressure-sensitive conductive silicone rubber composition. Got Further, to 100 parts of this composition, 1.5 parts of a solvent [HYALOM 2S manufactured by Nisseki Co., Ltd.] was added for dilution to obtain a pressure-sensitive conductive silicone rubber paste.

Example 1 As shown in the sectional view of FIG. 1, the size is 20 × 1000 mm and the thickness is
A 188 μm polyester film 1 is provided with two parallel electrodes 2 made of a polyurethane resin containing silver particles, and the electrode 2 is further covered with a polyurethane resin containing carbon to provide an electrode 3, thereby forming a first substrate. An electric circuit was formed on the film.

Next, as shown in the cross-sectional view of FIG. 2, a polyester film 11 having the same size as the first substrate film is formed of a polyurethane resin containing silver particles, and one of them is used to correspond to the above two electrodes 3. An electrode 12 is provided, which is also covered with a carbon-containing polyurethane resin in the same manner as the electrode 2 described above.
By providing, an electric circuit was formed on the second substrate film.

Further, the pressure-sensitive conductive layer 4 of the pressure-sensitive conductive silicone rubber obtained in Reference Example 2 was provided on the electric circuit of the second substrate film shown in FIG. 2 with a thickness of 40 μm. A cross-sectional view of the pressure-sensitive conductive layer 4 formed is shown in FIG.

Next, as shown in FIG. 4, the electric circuit film having the pressure-sensitive conductive layer shown in FIG. 3 and the electric circuit film shown in FIG. 1 are adhered so that the electrodes 2 and 3 and the electrodes 12 and 13 correspond to each other. The keying force sensor 6 was constructed by bonding with the agent 5.

In the sensor shown in FIG.
The electrode 2 of the book is provided so that the electrode can be taken out from one of the substrates, which is excellent in mountability, and the two electrodes are arranged in parallel in each part of the keyboard in the longitudinal direction of the sensor. This is because the keystroke strength of is detected under the same conditions.

Comparative Example 1 Same as Example 1 except that the formation of the pressure-sensitive conductive layer of Example 1 was replaced with an assembly using a pressure-sensitive conductive rubber sheet having a thickness of 0.5 mm (manufactured by Yokohama Rubber Co., Ltd.). A keystroke force sensor was constructed.

[Effects of the Invention] In order to evaluate the keystroke force sensor of the present invention, as shown in FIG. 5, the keystroke force sensor 6 is attached to the upper surface thereof with the felt 8 by the double-sided adhesive tape 7, and further the keyboard 9 of the electronic organ. The lower mounting plate 10 was attached and set with a double-sided adhesive tape.

For the evaluation, DC5V was applied between the two parallel electrodes 2 in FIG. 1 and the relationship between the load and the output voltage when a load was applied to the keyboard and its variation were measured. Fig. 6 shows the results when 10 times measurements were made with the load position on the keyboard at the same place, and Fig. 7 shows the load position on the keyboard changed every 50 mm.
The results of 10 measurements are shown. In the graph, the solid line connects the average values and the broken line connects the maximum and minimum values. As can be seen from FIG. 6 and FIG. 7, the keying force sensor of the present invention has characteristics with excellent reproducibility with almost no variation.

On the other hand, the keying force sensor of Comparative Example 1 was also evaluated in the same manner. Fig. 8 shows that the load positions on the keyboard are the same.
The results of 10 times of measurement are shown in FIG. 9, and the results of the measurement of 10 times by changing the load position on the keyboard every 50 mm are shown. From FIGS. 8 and 9, the keystroke force sensor of Comparative Example 1 has different output voltage values each time it is measured, and it is difficult to obtain reproducibility.

As described above, according to the present invention, a keystroke force having a novel structure, small variations in load and output voltage characteristics, excellent reproducibility, thinness, and mass productivity capable of integration can be obtained. A sensor is provided.

[Brief description of drawings]

1 to 4 are views for explaining an embodiment of the present invention,
FIG. 1 is a schematic sectional view of a first substrate having an electric circuit, FIG. 2 is a schematic sectional view of a second substrate having an electric circuit, and FIG.
A schematic cross-sectional view of a second substrate provided with a pressure-sensitive conductive layer on the electric circuit of the figure, FIG. 4 is a schematic cross-sectional view of a keystroke force sensor, and FIG. 5 is an explanatory view of a test method for evaluating the keystroke force sensor. 9 to 9 are graphs for explaining the effect of the present invention. 1 ... 1st electrically insulating substrate (polyester film), 11 ... 2nd electrically insulating substrate (polyester film), 2, 12 ... silver electrode, 3, 13 ... carbon coated electrode, 4 ... Pressure-sensitive conductive layer, 5 ... Adhesive layer, 6 ...
Keystroke sensor, 7 ... double-sided adhesive tape, 8 ... felt, 9 ... keyboard, 10 ... sensor mounting plate.

Claims (5)

[Claims] 1. An electric circuit formed on a first electrically insulating substrate and covered with a carbon electrode; and a second electrically insulating substrate formed on a carbon electrode and covered by a carbon electrode. An electric circuit disposed with a gap from the electric circuit of the first substrate; and the first and second electric circuits.
Of the pressure sensitive conductive layer, which is deposited on at least one of the substrates and is disposed in the gap. 2. The first and second electrically insulating substrates are flexible insulating substrate films or resin plates having a thickness of 0.015 mm to 2 mm, respectively. Keystroke sensor. 3. The pressure-sensitive conductive layer is formed by a paste prepared by dispersing surface-treated conductive metal powder and carbon black in silicone rubber. Keystroke force sensor described in item. 4. The pressure-sensitive conductive layer has a thickness of 10 μm or more and 80 μm or more.
The keystroke force sensor according to claim 1, wherein the keystroke force sensor is less than m. 5. The first and second electrically insulative substrates are bonded together with an electric circuit and a pressure-sensitive conductive layer in the middle, and integrated. Keystroke sensor.