JPH05326217A - Pressure-sensitive variable resistor - Google Patents

Abstract

PURPOSE:To obtain a variable resistor which can be applied easily to a keyboard switch or the like. CONSTITUTION:Carbon powder such as carbon black or graphite is admixed with a silicon rubber material and molded integrally to produce a pressure- sensitive variable resistor 1. When the pressure-sensitive resistor 1 is applied to a switch 5, for example, the pressure-sensitive variable resistor 1 is applied through a conductive layer 7 to the bottom surface of a key top 6. The pressure- sensitive variable resistor 1 contacts with fixed contacts 9, 10 upon depression of the key top 6. The pressing force increases contacting pressure of the carbon powder and anisotropic conducting function takes place between the fixed contacts 9, 10 and the conductive layer 7. Resistance of the pressure-sensitive variable resistor 1 varies depending on the pressing force and the voltage between the fixed contacts 9, 10 can be varied arbitrarily through manual operation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable resistor, and more particularly to a solid structure variable resistor.

[0002]

2. Description of the Related Art Conventionally, a variable resistor composed of a resistor and a sliding contact has been used for adjusting a circuit voltage. Further, a sensor such as a strain gauge utilizing the characteristics of a semiconductor pressure sensitive element whose electric resistance changes with stress is widely known.

[0003]

For example, a cursor movement key and a scroll key of a computer, a power window switch of an automobile, etc. are simply switches for turning on and off. If a function capable of analogly adjusting the operation amount according to the operator's intention is added to these keys or switches, the performance improvement as a so-called man-machine interface can be expected.

In order to realize this analog operation,
Needless to say that the hardware and software have to be changed, it is necessary to use a variable resistor as the electric quantity operating means for the key or the switch. However, applying the conventional variable resistor to these keys and switches has problems in volume, weight, durability and cost. For example, using a conventional mechanical variable resistor for a key of a keyboard causes problems in space, durability, and operability.

Therefore, the present invention provides a variable resistor which has a simple structure and high durability, can obtain a resistance change corresponding to the operation feeling, and is low in cost to improve the function of electronic equipment. The purpose is to contribute.

[0006]

In order to achieve the above object, the present invention is a pressure-sensitive variable resistor in which a conductive substance such as carbon powder is mixed with an elastic rubber material and integrally molded to give anisotropic conductivity. Is proposed.

[0007]

The conductive material such as carbon powder mixed in the elastic rubber material has a low contact pressure between the conductive materials in a normal state, and has an electrically high resistance. When pressure is applied to both sides of this elastic rubber material, the elastic rubber material is deformed by the stress, the contact pressure between the conductive materials in the stress direction increases, the resistance value decreases, and anisotropy that allows conductivity in the stress direction is obtained. The conductive action of appears. Since the resistance value changes almost proportionally to the stress,
The change in load stress can be easily grasped as the change in resistance value.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 1 shows a pressure-sensitive variable resistor 1 formed by mixing an elastic rubber material such as silicon rubber with carbon powder such as carbon black or graphite to form a rubber plate having an appropriate thickness.
As shown in FIG. 2, when the electrodes 3 and 4 of the power supply 2 are connected to both sides of the pressure sensitive variable resistor 1 and stress is applied to both sides of the pressure sensitive variable resistor 1, contact between carbon powders in the stress direction is generated. The state changes, and the anisotropic conductive action shown by the arrow appears.

FIG. 3 shows the relationship between the stress F and the resistance value R, which is a high resistance in the stress-free state, and the contact state of the carbon powder in the stress direction becomes dense and changes to a low resistance as the pressure increases. To do. Therefore, by measuring the voltage between the electrodes 3 and 4, the stress can be converted into an electric quantity and expressed, and can be used for a load meter or the like. Incidentally, it is possible to provide resistors having various resistance value ranges and load powers depending on the volume and cross-sectional aspect ratio of the pressure-sensitive variable resistor 1, hardness, and mixing ratio of carbon-based powder.

FIG. 4 shows an example in which the pressure sensitive variable resistor 1 is applied to the switch 5, and the pressure sensitive variable resistor 1 is used for the movable contact of the rubber key top 6. A conductive layer 7 is provided between the pressure sensitive variable resistor 1 and the rubber key top 6.
The conductive layer 7 is formed on one surface of the pressure-sensitive variable resistor 1 by printing or integral molding. When the rubber key top 6 is pushed down, the pressure sensitive variable resistor 1 comes into contact with the two fixed contacts 9 and 10 arranged on the circuit board 8 as shown in FIG. A circuit is formed between the two fixed contacts 9 and 10 via the anisotropic conductive paths a and b and the conductive layer 7 thereabove, but when the contact pressure is low, the resistance value of the pressure sensitive variable resistor 1 is increased. Is high, the resistance value decreases as the contact pressure is increased by further pressing the rubber key top 6.

For example, if the switch 5 is used as a constituent element of an oscillation circuit, the oscillation frequency can be arbitrarily controlled by the pressing force. Therefore, if the switch 5 is used for a scroll key and a cursor movement key of a computer keyboard and the hardware and software are made to correspond so that the scroll speed and the cursor movement speed change depending on the resistance value, It is possible to freely control the scroll speed, the cursor movement speed, the reaction speed of the character in the computer game, etc. according to the intention.

The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention, and it goes without saying that the present invention extends to those modifications. Is.

[0013]

As described in detail in the above-mentioned embodiment, the pressure-sensitive variable resistor of the present invention is a solid resistor whose resistance value can be varied by the pressing force, so that almost no failure such as disconnection occurs. It has excellent productivity and can be mass-produced at low cost. Further, since it is a solid type without a slider, it can be easily applied to a keyboard, a controller, etc., and the application range of the variable resistor can be expanded to contribute to the function improvement of various electronic devices.

[Brief description of drawings]

FIG. 1 is a front view of a pressure-sensitive variable resistor according to the present invention.

FIG. 2 is an explanatory diagram showing the operation of a pressure sensitive variable resistor.

FIG. 3 is an explanatory graph showing the relationship between stress and the resistance value of the pressure-sensitive variable resistor of the present invention.

FIG. 4 is a cross-sectional view of a switch using a pressure sensitive variable resistor.

5 is an explanatory diagram showing a current path when the switch of FIG. 4 is in an ON state.

[Explanation of symbols]

 1 Pressure Sensitive Variable Resistor 2 Power Supply 3, 4 Electrode 5 Switch 6 Rubber Key Top 7 Conductive Layer 8 Circuit Board 9, 10 Fixed Contact

Claims (1)

[Claims] 1. A pressure-sensitive variable resistor in which a conductive material is mixed with an elastic rubber material and integrally molded to impart anisotropic conductivity.