JPH0347527B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a plane coordinate input tablet for inputting two-dimensional patterns such as characters and images.
In detail, it is a pressure-type plane coordinate input tablet using a resistance sheet, and it is a plane coordinate input tablet that can stably detect the pressure input point with high precision even if pressure input is repeated over a long period of time. related to tablets. Planar coordinate input tablets are classified into resistance sheet type, conductive sheet type, optical scanning type, surface wave propagation time detection type, strain gauge type, etc. according to their operating principles. Among these, the resistance sheet type tablet detects the position coordinates of the input point on the resistance sheet from electrical signals such as the ratio of current and voltage, so it has a simple structure in principle, but it is not practical in practice. It is required that the resistance value of the resistance sheet used be uniform in each part on the sheet, and that the resistance value remains constant even after repeated use. However, conventionally known resistive sheet type tablets generally have a problem in that the resistance value of the resistive sheet increases with repeated use, causing distortion in reproduced images. In addition, the resistance sheet in the conventionally known input tablet is made by applying so-called carbon paste, in which conductive material such as carbon powder is dispersed in thermosetting synthetic resin, on one side of an insulating substrate made of a synthetic resin sheet. The resistive sheet is formed by drying and curing after applying it by screen printing, roller coating, etc., so the uniformity of the dispersion of the conductive particles in the paste and the uniformity of the coating thickness are not sufficient. , the input position coordinates do not exactly match the current or voltage ratio, and there is also the problem that the reproduced image is distorted. The present invention solves the above-mentioned problems and provides a tablet for plane coordinate input that has a constant sheet resistance even after repeated use over a long period of time, and therefore provides stable and accurate reproduced images over a long period of time. A further object of the present invention is to provide a tablet for plane coordinate input that can accurately detect input positions from electrical signals such as voltage or current ratios, and is inexpensive to manufacture. shall be. The tablet for plane coordinate input according to the present invention has a resistor layer on an insulating substrate, and a resistor sheet having band-shaped electrodes on two opposing edges is connected to the resistor layer through a pressure-sensitive conductive sheet. A tablet for plane coordinate input, in which layers are stacked so as to face each other, and detects the position coordinates of a pressure input point on a resistance sheet by an electrical signal,
Tensile modulus of elasticity 5×10 ³ to 15 on the insulating substrate on the input side
A protective sheet made of at least one kind of polymer selected from polyamide, polyamide copolymer, and fluororesin of x10 ³ Kg/cm ² is provided. The present invention will be described below based on drawings showing examples. In the tablet for plane coordinate input according to the present invention, the resistance sheet 10 includes an insulating substrate 4 and a resistor layer 9 formed thereon, as shown in FIG.
and a band-shaped electrode 6 provided on two opposing edges of the substrate. The tablet for plane coordinate input according to the present invention has an insulating substrate 4 as shown in FIG.
a lower resistance sheet 11 having a resistor layer on A;
An upper resistor sheet 13 having a resistor layer on an insulating substrate 4B is provided on opposite edges of the lower resistor sheet while these resistor layers face each other with a pressure-sensitive conductive sheet 12 in between. The strip-shaped electrode 6Y and the similar electrode 6X of the upper resistance sheet are stacked so as to be perpendicular to each other, and a protective sheet 14 is further stacked on the pressure input side, that is, on the insulating substrate 4B of the upper resistance sheet. The positional coordinates of the pressure input point applied to each resistive sheet through the protective sheet are detected by electrical signals. In the present invention, the resistance sheet may be a sheet formed by applying and curing a so-called conductive paste, which is made by dispersing conductive powder such as carbon powder or metal powder in a thermosetting resin, on an insulating substrate. However, preferably, as explained below, the resistor sheet includes a main resistor layer made of a metal thin film provided on an insulating substrate, and a protective resistor layer covering the surface of the main resistor layer. It has a double structure. To form a metal thin film as the main resistor layer on an insulating substrate, vacuum evaporation, cathode sputtering, electroless plating, CVD (chemical vapor deposition), etc.
It is possible to use any conventionally known technique such as ion plating or ion plating, but it is easier to make the metal thin film sheet resistance value uniform compared to the method of directly forming a metal thin film on an insulating substrate. Preferably, electroplating is used because it provides strong adhesion to the insulating substrate, and there is no need to expose the insulating substrate to high temperatures when forming the metal thin film. The above-described resistance sheet and a tablet for inputting plane coordinates using the same will be explained below with reference to the drawings. One side of the copper foil 1, which will become a conductive layer, is coated with a masking adhesive sheet 2, and then, as shown in FIG. A main resistor layer 3 made of a metal thin film is formed. As for the thickness of the main resistor layer 3 formed by electroplating, since the copper foil surface is highly smooth, a practical thin film of 200 mm can be obtained at its thinnest thickness. Next, as shown in FIG. 4, the adhesive sheet 2 is peeled off, and a flexible insulating substrate 4 is bonded to the surface of the main resistor layer 3. At the opposite edges of the three-layer laminate thus obtained, a fifth
Attach masking tape 5 as shown in the figure,
Next, when the exposed portion of the copper foil 1 is etched away using a copper etching solution, as shown in FIG.
A resistance sheet is obtained in which electrodes 6, 6 are formed on opposite edges of the main resistor layer 3. As shown in FIG. 7, on the main resistor layer 3,
A protective resistor layer 7 is formed. This protective resistor layer is a wear-resistant layer that is formed by applying a paste or ink containing a conductive material powder such as carbon or metal powder and a thermosetting synthetic resin onto the main resistor layer and curing it. It is a resistor layer rich in The sheet resistance value of this protective resistor layer is preferably 10 times or more the sheet resistance value of the main resistor layer. Also,
When applying the paste onto the main resistor layer, the paste is screen printed or the like so that the protective resistor layer 7 not only completely covers the entire surface of the main resistor layer 3 as shown in FIG. , 6 inner edge 8, 8
It is preferable to also cover the In such a resistor sheet, the resistance value is a parallel composite value of the resistance values of the main resistor layer 3 and the protective resistor layer 7, but the resistance value of the main resistor layer 3 dominates the composite value. Therefore, as long as the sheet resistance value of the main resistor layer 3 is uniform, even if the sheet resistance value of the protective resistor layer 7 is non-uniform, the effect on the composite value is small. Furthermore, the resistance value due to the protective resistor layer 7 is added in series at the input coordinate point, but the thickness of the protective resistor layer 7 is extremely small, for example, 10 μm, and the area related to conduction is, for example, 1 mm ² compared to the thickness. Since the resistance value is sufficiently large, the increase in resistance value can be practically ignored. As the insulating substrate, a relatively hard and thick sheet made of polyester (polyethylene terephthalate, hereinafter the same) is used so that it can withstand pressure from an input pen and has flexibility. In addition, polyamide, polyimide, polyethylene, polyvinyl chloride, polytrifluoroethylene, polytetrafluoroethylene,
A sheet made of a tetrafluoroethylene-hexafluoropropylene copolymer, an acrylic-epoxy copolymer, a copolymer thereof, or the like is used.
In addition to the tin-nickel alloy, nickel alloys such as nickel-chromium and nickel-phosphorus having a sheet resistance value of 20 to 2000 Ω/□, tantalum nitride, and the like are also used as the main resistor layer. In the tablet for plane coordinate input according to the present invention, the protective sheet has a tensile modulus of 5×
Comprising a polymer of 10 ³ to 15×10 ³ Kg/cm ² , relatively flexible and elastic, with a thickness of 80 to 500 μm,
Preferably, a sheet of 100 to 400 μm is used.
Such a protective sheet does not cause permanent deformation of itself or the insulating substrate even if pressure is repeatedly applied thereto, and also suppresses the increase in the resistance value of the resistive sheet over time, making it suitable for long-term use. The pressure input point can be detected with high accuracy even if the pressure input point is different. In particular, in the present invention, sheets made of polyamides having the above properties, copolymers thereof, fluororesins such as polytrifluoroethylene, polytetrafluoroethylene, and tetrafluoroethylene-hexafluoropropylene copolymers are preferably used. However, among them, so-called nylon 6, nylon 6
6. Nylon 610, Nylon 11, Nylon 1
A sheet made of a non-stretched polyamide or a copolymer thereof having these as main components is preferably used. In addition, such a polymer has a tensile modulus within the above-mentioned predetermined range and a yield point strength of 200 to 200.
Preferably it is in the range of 800Kg/cm ² . A particularly preferred polyamide is "Diamond 7000" (manufactured by Daicel Corporation) film or sheet. This film or sheet has a tensile modulus of 6×10 ³ to 12×10 ³ Kg/cm ² and a yield point strength of 330 to 450.
Kg/ ^cm2 . Unfortunately, polyester has a tensile modulus of 35.
×10 ³ ~50×10 ³ Kg/cm ² , yield point strength approximately 1200 Kg/cm ²
It is. In particular, in the present invention, when the resistance sheet is composed of a main resistor layer made of a metal thin film and a protective resistor layer on an insulating substrate, the sheet or film used on the insulating substrate is smaller than the protective sheet. The tensile modulus and yield point strength are preferably about 50% or less. Therefore, the above-mentioned "Diamide" can be used as a protective sheet.
When using "Diamide 7000", "Diamide 7000" can also be used as the insulating substrate, but it is more preferable to use "Diamide 3000". Here,
"Diamid 7000" film or sheet has a Young's modulus (100%) of 8000 Kg/cm ² and yield point strength of 450 Kg/cm ² , while "Diamid 3000" film or sheet has a Young's modulus (100%) of 1700 Kg/cm 2 ² , yield point strength is 150Kg/cm ² . In addition, instead of the above-mentioned "Diamide 3000", polymers having approximately the same tensile modulus and yield point strength as this, such as tetrafluoroethylene-hexafluoropropylene copolymer or acrylic acid ester-epoxy resin copolymer, may be used. Combination etc. can also be used. In the input tablet of the present invention, as described above, a sheet made of a polymer having the above-mentioned predetermined properties is used as a protective sheet for the insulating substrate on the pressure input side. This seems to be because it is flexible and has appropriate elasticity, but unlike the conventional protective sheet made of polyester, permanent deformation does not occur in the protective sheet and the resistor layer on the insulating substrate when pressure is applied. Moreover, the resistance value of the resistance sheet remains constant over time. Therefore, according to the tablet for plane coordinate input according to the present invention,
The pressure input point can be detected stably and with high precision over a long period of time. Further, according to a preferred embodiment of the present invention, since the main resistor layer is composed of a metal thin film having a uniform sheet resistance value, a high quality image signal can be obtained. When formed, the copper foil surface is a highly precise smooth surface, and an image signal of even higher quality can be obtained. According to the present invention, even if the main resistor layer is a thin film with a thickness of about 200 Å, its surface is covered with the protective resistor layer, and as described above, the protective sheet is used as the protective sheet. Since a sheet made of such a predetermined polymer is used, the pressure input point can be detected stably and with high precision over a long period of time. Example 1 One side of a copper foil with a thickness of 35 μm and an area of 35 cm x 35 cm was covered with a masking adhesive sheet, and a degreasing liquid and 20%
After dipping in hydrochloric acid and rinsing with water, the other side of the copper foil is electroplated to a thickness of approx.
A thin film of 500 Å of tin-nickel alloy (approximately 70% tin by weight, remainder nickel) was formed. For this three-layer structure, the adhesive sheet is peeled off from the copper foil, an acrylic resin adhesive is applied to the surface on which the tin-nickel alloy thin film is formed, and an insulating substrate is placed on this to a thickness of approximately 50 μm (2 mils). ) polyester films were stacked and bonded together by thermocompression, and then 2.5 cm of each of the four sides was cut and removed to obtain a square sheet of 30 cm on each side. Next, masking tape was applied to the 10 mm wide portions of the opposing sides, and the exposed copper was etched away using an ammonia-based copper etching solution, washed with water, and then dried. Next, the masking tape at both ends was peeled off to obtain a resistance sheet with 10 mm wide copper electrodes at both ends. The average sheet resistance value of this resistance sheet was 500Ω/□, and the variation in each part was within ±3%. Carbon paste (MCP-7002 manufactured by Mitsui Toatsu Co., Ltd.) with a resistance value of 10 kΩ/□ is applied to the surface of this resistor layer.
After screen printing using a 200 mesh polytetrafluoroethylene screen, it was cured. After curing, the sheet resistance was measured using a four-probe resistance measuring device and found to be an average of 480Ω/□, with variations within ±5% for each part. The two resistor sheets obtained in this way have a thickness of 0.5
mm pressure-sensitive conductive sheet (JSR manufactured by Japan Synthetic Rubber Co., Ltd.)
PCR 505-05) are laminated so that the resistor layers face each other, and then a film or sheet shown in Table 1 is layered as a protective sheet on the polyester insulating substrate of the upper resistance sheet. Using a regular commercially available pole pen, apply a load of 500g from above the protective sheet on a fixed line parallel to the opposing electrodes.
Writing was performed 1000 times, and the change in resistance value between the electrodes of the upper resistance sheet and the sensitivity of writing pressure were measured, and the deformation of the protective sheet was observed. The results are shown in Table 1. For the change in resistance value, the resistance value before the load test is R ₀ ,
When the resistance value after the test is R, it is given by (R-R ₀ )/R ₀ ×100 (%), and the pen pressure sensitivity is the load required to conduct current between the upper and lower resistance sheets ( (pen pressure). It is clear that in the tablet for plane coordinate input according to the present invention, the protective sheet is substantially free from permanent deformation and wear, and the resistance value of the resistance sheet remains constant at a high level. Example 2 In the same manner as in Example 1, a tin-nickel alloy thin film with a thickness of about 500 Å was plated on the surface of a 35 μm thick copper foil, and then on this plated metal thin film, as shown in Table 2, Resistance sheets were obtained by thermocompression bonding films made of various polymers as insulating substrates. These two resistance sheets were stacked together with a pressure-sensitive conductive sheet interposed therebetween in the same manner as in Example 1, and the upper resistance sheet was made of a polymer shown in Table 2 without laminating a protective sheet on the insulating substrate. Laminate the protective sheets, and apply 500g from above the protective sheet if the protective sheet is included, or from the top of the upper insulating substrate if the protective sheet is not included, in the same manner as in Example 1.
Write 1000 times with a normal commercially available pole pen under a load of
The resistance value between the electrodes of the upper resistance sheet was measured, and the deformation of the protective sheet was observed. The results are shown in Table 2. Example 3 As an insulating substrate, carbon paste (same as above) was applied using a roller coater to one side of a polyester film measuring 30 cm in length and width and having the thickness shown in Table 3.
was applied to a thickness of about 10 μm and cured by heating at 130° C. for 3 hours. The resistance value of the obtained resistance sheet is 490
Ω/□, and the variation in each part was ±10%.
Silver paste was printed to a width of about 5 mm on opposite edges of this resistor sheet to form counter electrodes. Next, attach these two resistor sheets to the thickness as described above.
The resistor layers were laminated so as to face each other with a 0.5 mm conductive sheet in between, and a protective sheet made of polyester or "Diamid 7000" was laminated on the insulating substrate of the upper resistor sheet, and in the same manner as in Example 1. Tested. The results are shown in Table 3. In this case as well, the protective sheet is substantially free from permanent deformation and abrasion, and the writing pressure may be small. Example 4 Carbon paste (same as above) was coated with a roll coater to a thickness of about 10 μm on a polyamide film “Diamid 7000” and a low melting point polyamide “Diamid 3000” having the thickness shown in Table 4 as an insulating substrate.
m, heat cured at a temperature of 110℃ for 1 hour,
Furthermore, a counter electrode is formed using silver paste, and the average sheet resistance value is 510Ω/□, and the variation in each part is ±10%.
A sheet was prepared and compared with a resistance sheet using the same 125 μm thick polyester film used in Example 3 as an insulating substrate. The results are shown in Table 4. According to the tablet for plane coordinate input of the present invention,
Permanent deformation of both protective sheet and insulating substrate

[Table] (Note) (1) Evaluation criteria are as follows. ○ means no permanent deformation, △ means permanent deformation is observed, and × means permanent deformation and significant wear. same as below.
(2) Lamination with 25 μm thick aluminum foil.

【table】

【table】

[Table] It is clear that there is no wear and tear, and the sheet resistance value remains constant at a high level.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an example of a resistance sheet.
FIG. 2 is an exploded perspective view showing an embodiment of the tablet for inputting planar coordinates according to the present invention, and FIGS. 3 to 7 are process diagrams showing the manufacturing process of the tablet for inputting planar coordinates shown in FIG. FIG. 7 is a sectional view showing a preferred embodiment of the resistance sheet according to the present invention. 3... Main resistor layer, 4, 4A, 4B... Insulating substrate, 6, 6X, 6Y... Electrode, 7... Protective resistor layer, 9... Resistor layer, 10... Resistance sheet, 1
1...lower resistance sheet, 13...upper resistance sheet.

Claims (1)

[Scope of Claims] 1. A resistor sheet having a resistor layer on an insulating substrate and having strip-shaped electrodes on two opposite edges, the resistor layer being opposite to each other through a pressure-sensitive conductive sheet. In a plane coordinate input tablet that is stacked so as to face each other and detects the position coordinates of a pressure input point on a resistance sheet using an electrical signal, a tensile modulus of elasticity of 5× is placed on an insulating substrate on the input side.
10 ³ ~15×10 ³ Kg/cm ² , yield point strength 200 ~ 800 Kg/cm ²
A tablet for inputting planar coordinates, characterized in that it is provided with a protective sheet having a thickness of 100 to 400 μm and made of at least one kind of polymer selected from polyamide, polyamide copolymer, and fluororesin. 2. Claim 1, characterized in that the resistance sheet consists of a main resistor layer made of a metal thin film provided on an insulating substrate, and a protective resistor layer covering the surface of the main resistor layer. A tablet for inputting plane coordinates as described in Section 1. 3. The tablet for plane coordinate input according to claim 1, wherein the main resistor layer is made of a metal thin film formed by electroplating. 4. The tablet for plane coordinate input according to claim 1, wherein the protective resistor layer is a mixture of carbon or metal powder and total resin. 5. Planar coordinate input device according to claim 2, 3, or 4, characterized in that the sheet resistance value of the protective resistor layer is 10 times or more the sheet resistance value of the main resistor layer. Tablet.