JPH05149816A - Detecting device of pressure - Google Patents

Abstract

PURPOSE:To make it easy to manufacture a device which may be used without being restricted by the kind of fluid or the like and being small in size and light in weight, by disposing a reflecting plate at a position at which an output current of a light- sensing element changes according to a change in the distance of the plate to a light- emitting element or the light-sensing element. CONSTITUTION:A light of a light-emitting diode 5 is reflected on a reflecting plate 4 and enters a phototransistor 6 and an output current IO flows therethrough. On the occasion, the current IO changes according to a distance alpha of the reflecting plate 4 to the diode 5 or the transistor 6 even when the quantity of light of the diode 5, i.e., a current IF thereof, is fixed. In a region wherein the distance alpha is small, the current IO becomes large with an increase of the distance, and when the distance exceeds a certain limit, the current IO becomes small gradually. By providing the reflecting plate 4 at the position where this current IO increases, a large change of the current IO is obtained for a small change in the distance alpha. Accordingly, even a very small change in the shape of the reflecting plate 4 due to a pressure can be known from the change of the current IO, and by measuring the correlation between the amount of this change of the current IO and the pressure beforehand, an absolute value of the pressure can be known directly from the current IO.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compact and lightweight pressure detecting device.

[0002]

2. Description of the Related Art Although various types of devices have been used for a long time for detecting and measuring pressure, as a small and lightweight device, a pressure sensor using a piezoresistive effect using a silicon semiconductor has recently been used. Has become widely used. Further, various ultra-compact pressure sensors to which microfabrication technology for LSI manufacturing is applied have also been proposed. FIG. 5 is a sectional view showing an example of a conventional pressure sensor utilizing the piezoresistive effect of a silicon semiconductor. The silicon semiconductor 10 is processed to form a thin diaphragm portion 11, and a diffusion resistance portion 12 is formed on the surface of the diaphragm portion 11 by diffusion or ion implantation.

[0003]

In a pressure sensor utilizing the piezoresistive effect of a silicon semiconductor, which has been widely used as a small and light pressure detecting device in the past, a diaphragm which deforms in response to a pressure is a thin film of the silicon semiconductor. so,
There is a problem that it is difficult to control the film thickness of this film, the manufacturing yield is poor, and the film becomes expensive. Further, the one to which the microfabrication technique of LSI manufacturing is applied requires expensive equipment and a special working environment, and there is a problem that the process becomes complicated. Also,
In these pressure sensors, there is a problem in that the material of the constituent elements is limited due to processing technology limitations, and therefore the environment in which the pressure sensor is used or the fluid in contact with the diaphragm is limited, so that the pressure sensor cannot be used. The present invention aims to solve the above problems.

[0004]

A pressure detecting device of the present invention comprises a light emitting element, a reflector for reflecting the light of the light emitting element,
The light receiving element receives the light reflected by the reflecting plate and outputs an electric current, and the pressure receiving part which is coupled to the reflecting plate and whose distance from the light receiving element changes with the change in pressure. When the distance to the light emitting element or the light receiving element changes, the output current of the light receiving element changes,
It is characterized in that a change in the output current of the light receiving element is detected as a change in pressure.

[0005]

FIG. 1 is a front view showing an embodiment of the present invention, and FIG.
FIG. 3 is an explanatory diagram schematically showing the configuration of an embodiment of the present invention. In the figure, 1 is a reflection type optical sensor body, 2 is leads of a light emitting element and a light receiving element of the reflection type optical sensor, 3 is a transparent and flexible polyethylene film, and 4 is formed on the surface of the polyethylene film 3 by vapor deposition. A reflector made of a metal layer of gold, silver, aluminum or the like, 5 is a light emitting diode, and 6 is a phototransistor.

FIG. 3 shows the distance d between the reflection type optical sensor and the reflection plate.
FIG. 6 is a graph showing an example of an output current I _O characteristic (detection sensitivity of reflected light) with the parameter as a parameter. When the light emitting diode 5 emits light, the light is reflected by the reflector 4 is incident on the phototransistor 6, flows an output current I _O to phototransistor 6. At this time, the output current I _O is the distance between the reflection plate 4 and the reflection plate 4 facing the reflection type photosensor, as shown in FIG. 3, even if the light amount of the light emitting diode 5, that is, the current I _F of the light emitting diode 5 is constant. It changes with d. In a region where the distance d is small, I _o increases as d increases, and
I _O As it exceeds the certain size, d is greater
Is getting smaller and smaller. Reflective optical sensor and reflector 4
If the reflection plate 4 is provided at a position where the output current I _O increases as the distance between and increases, a large change in the output current I _O can be obtained for a small change in the distance d. Therefore, even a slight deformation due to the pressure on the reflection plate 4 can be captured by the change in the output current I _O. If the correlation between the change amount of the output current I _o and the pressure is measured in advance, the absolute value of the pressure can be known directly from the output current I _o .

The output current I _O of the phototransistor 6 changes depending on the current I _F of the light emitting diode 5 and the bias voltage V _{CE of the} phototransistor 6. In a region where the distance d is small, I _o increases as d increases, and when d exceeds a certain size, I _o gradually decreases as d increases. This reflective optical sensor and reflector 4
If the reflection plate 4 is provided at a position where the output current I _o increases as the distance between and increases, a large change in the output current I _o can be obtained for a small change in the distance d. Therefore, even a slight deformation due to the pressure on the reflection plate 4 can be captured by the change in the output current I _O. If the correlation between the change amount of the output current I _O and the pressure is measured in advance, the absolute value of the pressure can be known directly from the output current I _O.

Since the output current I _O of the phototransistor 6 also changes depending on the current I _F of the light emitting diode 5 and the bias voltage V _CE of the phototransistor 6, the output current I _{O of the} phototransistor 6 is the current I _O of the light emitting diode 5. _F
The sensitivity can be easily adjusted by using the fact that the bias voltage V _CE of the phototransistor 6 itself changes. In addition, the current I of the light emitting diode is changed so that the light emission amount changes in a constant cycle or a constant regular waveform.
By controlling _F and processing the output current I _O according to its cycle or rule, it is possible to construct a system that can reduce noise or detect a specific signal.

Further, in the construction of the apparatus, the condition of the reflecting plate which is displaced by pressure is mainly pressure-displacement relationship, and there are almost no restrictions on materials and materials. Therefore, the environment to be used and the magnitude of pressure to be detected are large. The degree of freedom can be selected according to the degree. FIG. 4 is an explanatory diagram showing the configuration of another embodiment of the present invention for achieving high linearity of pressure vs. output current.
4 is the same or corresponding to the same reference numeral in FIG.
Reference numeral 7 is a housing, 8 is a reflection type optical sensor mount, and 9 is a pressure receiving cone. With such a structure, the sensitivity to pressure is improved.

[0010]

As described above, according to the present invention, the condition of the reflector is mainly pressure-displacement relationship, and the degree of freedom can be selected depending on the environment used and the magnitude of pressure to be detected. There is an effect that the pressure detecting device can be used without being restricted by the environment in which it is used and the kind of fluid in contact with the diaphragm, and that a small and lightweight pressure detecting device can be easily manufactured.

[Brief description of drawings]

FIG. 1 is a front view showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram schematically showing the configuration of an embodiment of the present invention.

FIG. 3 is a graph showing an example of an output current I _O characteristic (reflection light detection sensitivity) with a distance d between a reflection type optical sensor and a reflection plate as a parameter.

FIG. 4 is an explanatory diagram showing the configuration of another embodiment of the present invention in which the linearity of pressure vs. output current is measured.

FIG. 5 is a sectional view showing an example of a conventional pressure sensor utilizing the piezoresistive effect of a silicon semiconductor.

[Explanation of symbols]

 1 Reflective Optical Sensor Main Body 2 Lead 3 Polyethylene Film 4 Reflector 5 Light Emitting Diode 6 Phototransistor

Claims (1)

[Claims] 1. A light emitting device, a reflector for reflecting the light of the light emitting device, a light receiving device for receiving the light reflected by the reflector and outputting an electric current, and a light receiving device coupled with the reflector for changing the pressure. The reflector is arranged at a position where the output current of the light receiving element changes when the distance to the light emitting element or the light receiving element changes, and the light receiving element A pressure detection device, which detects a change in output current of the device as a change in pressure.