JPH02100220A - Touch sensor - Google Patents

Abstract

PURPOSE:To detect a touch independent of hum by installing a light source and a light receiving element so that they face the prism face where total reflection condition is satisfied. CONSTITUTION:Light emitted from an LED 2 into a prism 1 is totally reflected on its total reflection face 1a, and the reflected light is received by a phototransistor 3. If the total reflection face 1a of the prism 1 is touched with a hand or similar means, the total reflection conditions are lost so that the light is made exit outside the prism 1 to have output of the phototransistor 3 deteriorated, and a touch is detected. This enables a touch switch independent of hum to be constituted with a relatively simple structure of a light detecting element.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to touch sensors.

[Conventional technology]

Conventionally, this type of touch sensor generally detects hum when touched electrically.

[Problem to be solved by the invention]

The above-mentioned conventional touch sensors generally have complicated input circuits, and have the disadvantage that they cannot be detected in areas where there is little hum.

The object of the present invention is the above-mentioned w! The objective is to provide a touch sensor that solves the problem.

(Means for Solving the Problems) In order to achieve the above object, a touch sensor according to the present invention includes a combination of a prism, a light source and a light receiving element that receives light emitted from the light source, and includes a combination of a prism, a light source, and a light receiving element that receives light emitted from the light source. The light-receiving elements are placed facing each prism surface where the total internal reflection condition is met.

〔Example〕

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the present invention.

In the figure, 1 is a prism whose cross section is an isosceles right triangle. In the present invention, an LED (light source) 2 is disposed on one prism surface 1b adjacent to the prism 1 across the total reflection surface 1a, and the reflected light reflected at the total reflection surface 1a is placed on the other prism surface 1c. A phototransistor (photodetection element) 3 that receives light is arranged.

In the embodiment, the light incident on the prism 1 from the LED 2 is totally reflected on its total reflection surface 1a, and the reflected light is received by the phototransistor 3. Here, if the total reflection surface 1a of the prism 1 is touched with a hand or an equivalent means, the total reflection condition is broken and the light is emitted outside the prism 1. Therefore, the output of the phototransistor 3 decreases, and this causes the tentacle to Detected.

In the embodiment, the prism 1 whose cross section is an isosceles right triangle is used, but the cross-sectional shape of the prism 1 may be other than this. A similar effect can be obtained by placing them facing each other on the prism surface.

〔Effect of the invention〕

As explained above, one aspect of the present invention has the effect that a touch switch that does not depend on hum can be constructed by using a relatively simple configuration of a prism, a light source, and a photodetecting element.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention. 1... Prism 1a... Total reflection surface lb
, lc...prism surface 3...phototransistor

Claims (1)

[Claims] (1) It consists of a combination of a prism, a light source, and a light-receiving element that receives light emitted from the light source, and is characterized in that the light source and the light-receiving element are placed facing respective prism surfaces where total reflection conditions are satisfied. touch sensor.