KR100989979B1 - Pressure sensitive conductive sheet and touch panel using the same - Google Patents

Abstract

While forming a 1st resistor layer on the lower surface of a film-form base material, the 2nd resistor layer in which particle | grains from which a particle diameter differs is superimposed, and is formed in this lower surface, and comprises a pressure-sensitive conductive sheet. With this configuration, since the second resistor layer formed into the uneven shape is in contact with the fixed contact according to the pressing force, and the electrical connection is made through the second resistor layer and the first resistor layer, the variation of the resistance value due to the repeated operation is changed. This small and thin panel switch capable of obtaining a stable resistance value can be realized.

Description

PRESSURE SENSITIVE CONDUCTIVE SHEET AND TOUCH PANEL USING THE SAME}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention mainly relates to a pressure sensitive conductive sheet used for the operation of various electronic devices and a panel switch using the same.

In recent years, with the advancement and diversification of various electronic devices such as mobile phones and car navigation systems, various and reliable operations are also required for panel switches used for these operations.

Such a conventional panel switch will be described with reference to FIGS. 8 and 9. In addition, sectional drawing in these drawings has expanded and showed the dimension of the thickness direction in order to make a structure clear.

8 is a cross-sectional view of a conventional panel switch. In FIG. 8, the pressure reduction conductive sheet 1 is comprised from the base material 2, such as insulating silicone rubber. The base material 2 is an amorphous shape which disperse | distributed carbon etc. to silicon etc., and the electroconductive particle 3 of size 20-200 micrometers is disperse | distributed in it. The board | substrate 4 is arrange | positioned at the lower surface of the pressure sensitive conductive sheet 1, and the several fixed contact points 5A and 5B, such as silver and carbon, are formed in the upper surface. In addition, a spacer 6 is formed between the pressure-sensitive conductive sheet 1 and the substrate 4 by insulating resin so as to surround the fixed contacts 5A and 5B. And the lower surface of the pressure-sensitive conductive sheet 1 and the fixed contacts 5A, 5B face each other to form a panel switch.

The panel switch comprised in this way is attached to the operation part of an electronic device, and the some fixed contact 5A, 5B is connected to the electronic circuit (not shown) of a device via a lead wire (not shown) etc.

In the above configuration, when the upper surface of the pressure-sensitive conductive sheet 1 is pressurized, the pressure-sensitive conductive sheet 1 is bent downward, and the lower surface contacts the fixed contacts 5A and 5B. The compressed contact 5A and the fixed contact 5B are electrically connected to each other via the conductive particles 3 by compressing by the pressing force and bringing the conductive particles 3 in the base material 2 into close contact with each other.

9 is a resistance characteristic diagram of a conventional panel switch. In FIG. 9, as shown by the curve A, when a pressing force is further applied, the number or contact area of the conductive particles 3 in contact with the substrate 2 increases, resulting in a small resistance value. The electronic circuit detects these electrical connections and changes in the resistance value, and is configured to operate various functions of the device.

The pressure-sensitive conductive sheet 1 used for such a panel switch elastically deforms the substrate 2 by pressing as described above, so as to obtain a predetermined resistance value by contacting the conductive particles 3 in the substrate 2. Since it is comprised, the variation of the resistance value by repeat operation is large. As shown in Fig. 9, a change in resistance value may change from curve A to curve B by thousands of pressurization operations.

For example, initially, the resistance value R1 was several tens of kΩ at the pressing force P of 2 to 10 N. After the repeated pressing operation, the resistance value R2 was several kΩ at the same pressing force P, and the resistance was close to one digit depending on the pressing force. Value fluctuations may occur. Therefore, it is necessary to set the electronic circuit which detects a change of resistance value in anticipation of such a fluctuation.

In addition, the pressure-sensitive conductive sheet 1 is formed by dispersing the conductive particles 3 in the base material 2 such as silicone rubber, which is easily deformed, and requires a certain thickness. Usually, the thing of about 0.3-1 mm in thickness is used. In addition, Japanese Patent Laid-Open No. 2006-236988 is known as prior art document information concerning the invention of this application.

However, in the conventional panel switch, since the variation of the resistance value due to the repeated operation of the pressure-sensitive conductive sheet 1 is large, detection of the resistance value according to this variation is necessary. In addition, since a certain thickness is required, it is also difficult to reduce the overall thickness.

The present invention provides a pressure-sensitive conductive sheet having a small variation in resistance value, which can perform reliable operation, and which can be made thin, and a panel switch using the same.

The pressure-sensitive conductive sheet of the present invention is formed by forming a first resistor layer on the lower surface of the film-like base material and forming a second resistor layer on which the particles having different particle diameters are dispersed. Then, the second resistor layer formed into the uneven shape by the particles having different particle diameters contacts the fixed contact or the like according to the pressing force, and electrical connection such as the fixed contact is performed through the second resistor layer and the first resistor layer. . With such a configuration, the variation in the resistance value due to the repeated operation is small, and a stable resistance value change can be obtained, and the thickness can be reduced by forming two resistor layers on the lower surface of the substrate.

The panel switch of this invention is comprised by arrange | positioning the board | substrate with which the some fixed contact was formed in the lower surface of the said pressure sensitive conductive sheet. By such a configuration, a small change in the resistance value, reliable operation can be performed, and a panel switch that can be made thin can be realized.

According to the present invention as described above, it is possible to realize a pressure-sensitive conductive sheet and a panel switch using the same, which can be reliably operated and thin.

EMBODIMENT OF THE INVENTION Hereinafter, the Example of this invention is described using FIGS.

In addition, sectional drawing in these drawings has expanded and displayed the dimension of the thickness direction in order to make a structure clear.

(Example 1)

BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing of the panel switch in Example 1 of this invention. In FIG. 1, the base material 11 is a film shape with a thickness of 25-200 micrometers comprised from polyethylene terephthalate, a polycarbonate, a polyimide, etc. FIG. The lower surface of this base material 11 is formed with synthetic resins, such as phenol, epoxy, phenoxy, and fluororubber, in which the first resistor layer 12 having a sheet resistance value of 0.5 k? It is.

The second resistor layer is formed of a sheet resistance value of 50 kΩ to 5 MΩ / □ and a thickness of 1 to 50 µm by a synthetic resin in which carbon powder is dispersed, and is superposed on the lower surface of the first resistor layer 12. Further, in the second resistor layer 13, particles 14 having different particle diameters in a spherical shape having a particle diameter of 5 to 100 µm, such as urethane or glass, are dispersed in an amount of 10 to 80% by weight so that the pressure-sensitive conductive sheet 15 is Consists of.

The pressure-sensitive conductive sheet 15 is formed of the first resistor layer 12 on the substrate 11 by screen printing, and thereafter, the particles 14 are formed by screen printing using a plate of SUS300-100 mesh. It is produced by forming the dispersed second resistor layer 13. The board | substrate 16 is a film form, such as polyethylene terephthalate and polycarbonate, or plate shape, such as paper phenol and glass containing epoxy. The substrate 16 is disposed on the bottom surface of the pressure sensitive conductive sheet 15. Moreover, the some fixed contact 17A, 17B, such as silver, carbon, and copper foil, is formed in the upper surface of the board | substrate 16 at intervals of 0.2 mm back and forth.

The spacer 18 is formed between the pressure-sensitive conductive sheet 15 and the substrate 16 by insulating resin such as polyester or epoxy so as to surround the fixed contacts 17A and 17B. And the panel switch is comprised so that the 2nd resistor layer 13 and the fixed contact 17A, 17B may oppose the space around 10-100 micrometers.

The panel switch configured in this manner is attached to an operation unit of the electronic device. The fixed contacts 17A and 17B are connected to an electronic circuit (not shown) of the device through a lead wire (not shown) or the like.

It is sectional drawing at the time of the pressurization operation of the panel switch in Example 1 of this invention. In FIG. 2, when the upper surface of the pressure-sensitive conductive sheet 15 is pressurized, the pressure-sensitive conductive sheet 15 is bent downward, and the second resistor layer 13 at the location where the particles 14A and 14B having large particle diameters are dispersed. ) Contacts the fixed contacts 17A, 17B. Then, the fixed contact 17A and the fixed contact 17B are electrically connected through the second resistor layer 13 and the first resistor layer 12. At this time, the part which contacts the fixed contact 17A, 17B is the particle | grains 14A, 14B of large particle diameter currently disperse | distributed in the 2nd resistor layer 13. As shown in FIG.

3 is an enlarged cross-sectional view of a panel switch in Embodiment 1 of the present invention. In FIG. 3, when the pressing force is applied, the portion in which the particles 14C or 14D having a smaller particle size than the particles 14A or 14B in the second resistor layer 13 is dispersed also contacts the fixed contacts 17A and 17B. As a result, the resistance value between the fixed contact 17A and the fixed contact 17B is changed.

4 is a resistance characteristic diagram of a panel switch according to the first embodiment of the present invention. In FIG. 4, when only a portion where the particles 14A and 14B having the large particle diameters are dispersed in the second resistor layer is in contact with each other by being pressed by a small pressing force P1, the contact between the fixed contact 17A and the fixed contact 17B is prevented. The resistance value is represented by R3. The resistance value R3 is the contact resistances r1 and r2 of the second resistor layer 13 and the fixed contacts 17A and 17B of this portion in FIG. 3, and the first resistor layer between the particles 14A and 14B. (12) and the conductor resistance r3 of the 2nd resistor layer 13 are summed.

On the other hand, the part where the particle | grains 14C, 14D with small particle diameters in the 2nd resistor layer 13 are disperse | distributed by the pressing force P2 larger than P1 also contacted the fixed contact 17A and the fixed contact 17B. The resistance value of the state is represented by R4. The resistance value R4 is obtained by applying the contact resistances r4 and r5 of this part and the conductor resistance r6 in parallel with the resistance value R3 in FIG. Therefore, the resistance value R4 becomes smaller than the resistance value R3.

In this way, as the pressing force increases, the contact points to the fixed contacts 17A and 17B of the second resistor layer 13 formed in the uneven shape by the particles 14 having different particle diameters increase. Then, as the conductor resistances of the second resistor layer 13 and the first resistor layer 12 having different sheet resistance values are applied to the contact resistance, the resistance value changes as shown by the curve C. FIG. In addition, the electronic circuit detects an electrical connection between the fixed contact 17A and the fixed contact 17B and a change in the resistance value, and the operation of various functions of the device is performed.

Even when the above pressurization operation is repeated, the variation of the resistance value is small. For example, as shown in FIG. 4, even if it fluctuates from the curve C to the curve D by 1 million press operations, the difference between the resistance values R3 and R5 in the pressing force P1 is configured to be around several kΩ. That is, the second resistor layer 13 formed in the concave-convex shape by the particles 14 having different particle diameters contacts the fixed contacts 17A and 17B according to the pressing force, and the second resistor layer (with different sheet resistance values) Since electrical connection is made through 13) and the first resistor layer 12, it is possible to obtain a stable resistance value change with small variation in resistance value due to repetitive operation.

In the above description, the sheet resistance of the first resistor layer 12 is set to 0.5 k? -30 k? /? And the sheet resistance of the second resistor layer 13 is set to 50 k? -5 M? / ?. However, the first resistor layer 12 preferably has a sheet resistance of 2 kΩ to 10 kΩ / □ and the second resistor layer 13 has a sheet resistance of 100 kΩ to 1 MΩ / □, and is dispersed in the second resistor layer 13. It is preferable to also make the ratio of the particle | grains 14 into 50-70 weight%.

Fig. 5 is an actual view of the resistance characteristics of the panel switch in the first embodiment of the present invention. In FIG. 5, when the sheet resistance values of the first resistor layer 12 and the second resistor layer 13 are too small, the resistance value immediately decreases with a small pressing force as shown by the curve E. FIG. When the sheet resistance value is too large, the resistance value change is small with respect to the change in the pressing force as shown by the curve F. However, by setting the sheet resistance value as described above, a smooth resistance value change according to the pressing force such as curve C can be obtained.

Moreover, since the 1st resistive layer 12 and the 2nd resistive layer 13 are overlappingly printed and formed in the film-form base material 11, the pressure sensitive conductive sheet 15 is pressure-sensitive-conductive with thickness of 0.3 mm or less. The sheet 15 can be formed, and it is possible to easily thin.

As described above, according to the first embodiment, the first resistor layer 12 is formed on the lower surface of the film-shaped base material 11, and the second resistor layer in which particles 14 having different particle diameters are dispersed on this lower surface ( By overlapping 13), the 2nd resistor layer 13 formed in the uneven | corrugated shape contacts the fixed contacts 17A and 17B according to a pressing force. And since electrical connection is made through the 2nd resistor layer 13 and the 1st resistor layer 12 from which sheet resistance value differs, the fluctuation | variation of a resistance value by repetitive operation is small and a stable resistance value change can be obtained. In addition, the pressure-sensitive conductive sheet 15 capable of reducing the thickness can be obtained. In addition, by disposing the substrate 16 on which the plurality of fixed contacts 17A and 17B are formed on the lower surface of the pressure-sensitive conductive sheet 15, the variation in the resistance value is small and reliable operation can be performed, and the panel can be made thin. Switch can be realized.

(Example 2)

Example 2 will be described. In addition, the same code | symbol is attached | subjected to the part of the structure same as the structure of Example 1, and detailed description is abbreviate | omitted.

6 is a cross-sectional view of a panel switch in Embodiment 2 of the present invention. In FIG. 6, the 1st resistor layer 12 of sheet resistance value 0.5k (ohm)-30k (ohm) / square is formed in the lower surface of the film-form base material 11, similarly to the case of Example 1. FIG. However, in the second embodiment, the spacer 20 is formed on the outer periphery of the central portion of the lower surface of the first resistor layer 12 by insulating resin such as polyester or epoxy.

The second resistor layer 13 having the particles 14 dispersed therein is formed on the lower surface of the central portion of the first resistor layer 12 and the lower surface of the spacer 20 with sheet resistance values of 50 k? 5 M? / ?. The board | substrate 16 is a film form or plate-shaped board | substrate, The center fixed contact 22, such as circular silver, carbon, copper foil, is formed in the upper surface of the center part. Moreover, the outer periphery fixed contact 23 of ring shape or horseshoe shape is formed in the outer periphery.

On the outer circumferential fixed contact 23, a second resistor layer 13 on the lower surface of the spacer 20 is mounted. In addition, this contact part is adhesively connected by anisotropically conductive adhesive agent (not shown) or thermocompression bonding. And the panel switch is comprised so that the lower surface of the center part of the 2nd resistor layer 13 and the center fixed contact 22 may oppose at intervals of 10-100 micrometers.

In addition, a panel switch configured as described above is mounted to an operation unit of an electronic device, and the central fixed contact 22 and the outer fixed contact 23 are connected to an electronic circuit (not shown) of the device via a lead wire (not shown) or the like. The same thing as the case of Example 1.

In the above structure, when the upper surface of the pressure-sensitive conductive sheet 21 is pressed, the central portion of the pressure-sensitive conductive sheet 21 is bent downward. Then, the portion in which the particles 14 having the large particle diameter are dispersed in the second resistor layer 13 contacts the central fixed contact 22, and the second resistor layer 13 and the first resistor layer 12 therebetween. Through this, the center fixed contact 22 and the outer circumferential fixed contact 23 are electrically connected.

In addition, when the pressing force is applied, the portion where the particles 14 having small particle diameters are dispersed in the second resistor layer 13 also contacts the center fixed contact 22, thereby providing a gap between the center fixed contact 22 and the outer fixed contact 23. The resistance value is changed. That is, in the second embodiment, as the pressing force increases, the contact portion to the central fixed contact 22 in the center of the second resistor layer 13 formed in the uneven shape by the particles 14 having different particle diameters increases. Then, as the conductor resistance of the second resistor layer 13 and the first resistor layer 12 having different sheet resistance values is applied, a change in resistance value is applied between the central fixed contact 22 and the outer fixed contact 23. You can get it.

Fig. 7A is a partial plan view showing an arrangement state of fixed contacts constituting the panel switch in the second embodiment of the present invention. In Fig. 7A, a substantially circular central fixed contact 22 is formed on the upper surface of the substrate 16, and a ring-shaped or horseshoe-shaped outer peripheral fixed contact 23 is formed on the outer circumference thereof.

Fig. 7B is a partial plan view showing an arrangement state of fixed contacts constituting another panel switch in the second embodiment of the present invention. In FIG. 7 (b), by providing the semi-circular center fixed contacts 22A and 22B in the outer fixed contact 23, between the center fixed contact 22A and the outer fixed contact 23 and the center fixed contact 22B. ) And the outer circumferential fixed contact 23 may be configured to output two resistance values.

FIG.7 (c) is a partial top view which shows the arrangement state of the fixed contact which comprises the other panel switch in Example 2 of this invention. In FIG.7 (c), you may form the two center stationary contacts 22C and 22D in the shape of the comb tooth which mutually engages between two arcuate outer periphery fixed contacts 23A and 23B. With such a configuration, even when some center shift occurs between the second resistor layer 13 and the first resistor layer 12, a stable resistance value change can be obtained.

As described above, according to the second embodiment, the second resistor layer 13 in which the spacers 20 are formed on the outer periphery of the central portion of the lower surface of the first resistor layer 12 and the particles 14 having different particle diameters are dispersed on the lower surface thereof. ), The second resistor layer 13 on the bottom surface of the spacer 20 is mounted on the outer fixed contact 23 so that the change in resistance value is small and reliable operation can be performed, and the panel switch can be made thin. Can be realized. In addition, by changing the shape of the center fixed contact 22, the output of two resistance values or the output of a stable resistance value can be obtained.

The pressure-sensitive conductive sheet and the panel switch using the same according to the present invention have a favorable effect that the variation in the resistance value is small, reliable operation can be performed, and that a thinning can be obtained, and is useful for operation of various electronic devices.

1 is a cross-sectional view of a panel switch in Embodiment 1 of the present invention;

Fig. 2 is a sectional view of the panel switch in pressurization operation according to the first embodiment of the present invention;

3 is an enlarged cross-sectional view of a panel switch in Embodiment 1 of the present invention;

4 is a resistance characteristic diagram of a panel switch according to the first embodiment of the present invention;

5 is a measurement diagram of resistance characteristics of the panel switch according to the first embodiment of the present invention;

6 is a cross-sectional view of a panel switch in Embodiment 2 of the present invention;

7 (a) is a partial plan view showing an arrangement state of fixed contacts constituting a panel switch in Embodiment 2 of the present invention;

7 (b) is a partial plan view showing an arrangement state of fixed contacts constituting another panel switch in Embodiment 2 of the present invention;

Fig. 7 (c) is a partial plan view showing an arrangement state of fixed contacts constituting still another panel switch in Embodiment 2 of the present invention;

8 is a cross-sectional view of a conventional panel switch,

9 is a resistance characteristic diagram of a conventional panel switch.

Explanation of symbols for the main parts of the drawings

11: Base material 12: First resistor layer

13 second resistive layer 14 particle

15: reduced pressure conductive sheet 16: substrate

17A, 17B: fixed contact 18: spacer

20: spacer 21: pressure-sensitive conductive sheet

22, 22A, 22B, 22C, 22D: Center Fixed Contacts

23, 23A, 23B: outer fixed contact

Claims (4)

A film-shaped base material, A first resistor layer formed on the lower surface of the substrate, A second resistor layer formed on the lower surface of the first resistor layer Provided with Particles having different particle diameters are dispersed in the second resistor layer, The lower surface of the second resistor layer is formed in an uneven shape, The resistance value of the first resistor layer and the second resistor layer are different A reduced pressure conductive sheet characterized by the above-mentioned. A pressure-sensitive conductive sheet having a film-shaped substrate, a first resistor layer formed on the bottom surface of the substrate, and a second resistor layer formed on the bottom surface of the first resistor layer; A substrate disposed on a lower surface of the pressure-sensitive conductive sheet And, A plurality of fixed contacts are formed on the upper surface of the substrate, Particles having different particle diameters are dispersed in the second resistor layer, The lower surface of the second resistor layer is formed in an uneven shape, The resistance value of the first resistor layer and the second resistor layer are different Panel switch characterized in that. The method of claim 1, The said 2nd resistor layer is formed of the synthetic resin which disperse | distributed carbon powder, The pressure-sensitive conductive sheet characterized by the above-mentioned. The method of claim 2, And the second resistor layer is formed of a synthetic resin in which carbon powder is dispersed.

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