JPS60177216A - Device transducing mechanical displacement to electrical signal - Google Patents

Abstract

PURPOSE:To detect fine displacement under non-contacting state by generating constant photoelectromotive force at the photodetecting element of a photocoupler provided near a photointerrupter which converts two photodetection signals into electrical signals differentially. CONSTITUTION:When a difference in detected pressure is applied to pressure introduction ports 10 and 11, a diaphragm 3 is in a stationary state as long as the sum of force generated at the diaphragm 3 and the elastic force of a spring 6 is equal to the elastic force of a spring 7. The displacement quantity of a light shield plate 13 coupled with the diaphragm 3 is in specific proportional relation with its variation quantity of detected pressure. The photointerrupter 18 and photocoupler 19 are installed closely and thus placed under the same temperature condition, thereby correcting the temperature dependency of the light emitting element 14 and photodetecting elements 15a or 15b of the photointerrupter 18. Consequently, when the mechanical displacement quantity of the light shield plate is constant, the light output voltage e0 of the photodetecting element is a stable output after variation with temperature is compensated completely.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a displacement detector that converts minute mechanical displacements into electrical signals without contact.

Conventionally, sliding resistors, differential transformers, magnetoresistive elements, capacitance types, etc. have been used to convert mechanical displacement into electrical signals, but sliding types reduce accuracy due to frictional resistance, so other methods have been used. However, if electronic circuits were included, the cost would be high.

SUMMARY OF THE INVENTION In order to solve these problems, it is an object of the present invention to provide a displacement sensor that uses an optical system to detect small mechanical displacements without contact and with an inexpensive structure.

Embodiments of the present invention will be described below with reference to FIG.

FIG. 1 is a longitudinal side view of a pressure sensor that uses a displacement sensor, and shows a mechanism for guiding pressure or pressure difference using a diaphragm and converting minute displacement of the diaphragm membrane into an electrical signal.

Symbols (1) and (2) are diaphragm-cases, and (3) is a flexible diaphragm. A rigid thin plate-shaped center disk (4) and Q (51) are fixed to the center of the diaphragm (3) from both sides.

There is an adjustment screw (9) inside the diaphragm case (2).
There is a spring (6) whose elastic force is adjusted via a spring holder (8) by the rotation of the spring (6), and a spring (7) whose elastic force is constant is fixed inside the diaphragm case (1). .

IJO and 0.1) is the pressure inlet and the diaphragm (
3), pressure chambers (12a) and (12b) are formed.

1ifH1031 is attached to the central part of the flat plate of the center disk (4) in a direction perpendicular to the flat plate and interlocks with the diaphragm (3).

α chrysanthemums are elements (15B) and (15b) that emit parallel or nearly parallel infrared beams that are focused by a lens.
) has a light shielding plate 03 on the side opposite to the beam emitted from Q4).
The light-emitting element 04, the light-receiving elements (15a) and (15b) are fixed to the diaphragm case (1), and together with the light-shielding plate 3, form a photoincluster. do.

(g) and qη are electric wires leading to the light emitting element Q4) and the light receiving elements (15a) and (i5b), respectively.

FIG. 2 shows an electronic circuit using the detector according to the present invention, and the photointerrupter is shown in FIG.
).

Next, the operation of the above structure will be explained with reference to the embodiments shown in FIGS. 1 and 2.

In Figure 1, the detected pressure difference is expressed as pressure inlet 0 [and α
When applied to υ, the force generated on the diaphragm (3) due to the pressure difference between the pressure chambers (12a) and (12b) is
) is equal to the elastic force of the spring (7), the diaphragm (3) is at rest.

If the detected pressure changes from this state, the diaphragm (3)
The diaphragm (3) is displaced by an amount obtained by dividing the amount of change in the generated force by the sum of the spring constants of the spring (6) and the spring (7).

Therefore, in the structure shown in Figure 1, the diaphragm (3)
A certain proportional relationship can be obtained between the displacement amount of the light shielding plate 03 and the detected pressure change amount which are interlocked with each other.

Next, the operating principle of the photointerrupter described above will be explained in detail.

A light emitting element 0 station and light receiving elements (+5a) and (15b) are fixed facing each other in the center of the diaphragm case (1), and a center disk (4) is located at the center position to block the light beam from the light emitting element a chrysanthemum. Interlocking light shielding plates α3 are arranged to form a photointerrupter.

FIG. 5 and FIG. 6 illustrate the principle mechanism of the photointerrupter section. In Fig. 6a, the light shielding plate a3 is placed at approximately half the center of the light receiving elements (15a) and (15b), whereas in Fig.
This is an example in which the light beam passes through approximately half of the center of the light receiving elements (1sa) and (15b), and the light shielding plate 03 is placed on both sides of the light beam. The same effect can be obtained with respect to the relationship between the amount of light received by the elements (15a) and (15b).

The light shielding plate 03 connects the light emitting element a station and the light receiving element (15a), (1
When the light receiving elements (15a) and (15b) are located at the center position of the light beam (5b), the amount of light received by each of the light receiving elements (15a) and (15b) is equal.When the light receiving element (15a) and (15b) are displaced from the center position to the left or right, one of the light receiving elements receives the same amount of light. The amount of light received increases, and the amount of light received by the other light receiving element decreases.

Figure 4a shows the light receiving element (15) with respect to the displacement of the light shielding plate (c).
It is a characteristic diagram showing the relationship between the amount of light received in a) and (15b), where C is the amount of displacement of the light shielding plate (2), and QL is the amount of displacement of the light receiving element (15b).
5a) and (15b), light shielding plate (6)
When the displacement C of is zero, that is, at the neutral position, the amount of light received by the light receiving elements (15a) and (15b) is strong, and when the displacement of the light shielding plate (to) is at the lowest value εl, the amount of light received by the light receiving element (15a) is The amount of light received by the light receiving element (15b) is the maximum value, and the amount of light received by the light receiving element (15b) is the minimum value.

The displacement of the light shielding plate @ reaches the maximum value t in the opposite direction from the neutral position! The amount of light received by the light receiving element (+5a) is the minimum value when the displacement is
The amount of light received by the light receiving element (15b) shows the maximum value, and the light shielding plate (
6) When the difference between the electrical signals generated in the light receiving elements (15a) and (15b) due to the displacement is extracted as an output, the output ΔQL is the difference between the displacement ε of the light shielding plate α and A proportional relationship can be obtained.

FIG. 2 shows an embodiment of an electronic circuit according to the present invention, which will be described in detail below.

Terminal (a) and terminal wire are stabilized power supplies and indicate positive voltage and negative voltage terminals, respectively.The gradient is an operational amplifier, and @ is a direct current amplifier.(2), 9. (c), (c), and (e) indicate resistance. 0 is a transistor, O is a mechanical part of the photo ink converter, and a light emitting element and a light receiving element (
15a) and (15b) are also light emitting elements (19
It is a signal detector, that is, a photocoupler, which integrates a) and a light receiving element (19b) and has the same function and characteristics as the light emitting element and light receiving element of the photointerrupter (to).Hereinafter, αI will be referred to as a photocoupler. Name and explain.

The resistor (A) and the resistor (A) are connected in series, and their connection point is connected to the non-inverting input terminal of the operational amplifier wire.
One end of the terminal (E) is connected to the positive voltage terminal of the terminal (E), and the resistor (
The other end of the terminal wire is connected to the negative voltage terminal of the terminal wire.

A light receiving element (15a) of a photointerrupter (to).

(15b) has an anode terminal and a cathode terminal connected in parallel in opposite directions, one end of which is connected to the negative voltage terminal of terminal (E), and the other end connected to the input terminal of the amplifier (A). . Note that the resistance (c) is the light receiving element (15a), (1
5b) is a load resistor connected to both ends of the resistor.

The light receiving element (t9b) of the photocoupler DI has its cathode terminal connected to the negative voltage terminal of the terminal wire, and its anode terminal connected to the inverting input terminal of the operational amplifier (e). The resistor (c) is connected in parallel with the load resistor of the light receiving element (19b).

The output terminal of the arithmetic intensifier is connected to the base of the transistor via the resistor (c), the collector of the transistor (b) is connected to the positive voltage terminal of the terminal (c), and the emitter is connected to the light emitting element (19a). ) and the light emitting element Q→ are connected in series and connected to the negative voltage terminal of the terminal (E), so
The same current flows through the light emitting element (19a) and θ→.

In the above circuit, if the power supply voltage is V, the non-inverting input of the operational amplifier is possible, and the voltage is V+, then V s = -V is applied to the emitter of the transistor R+
+R2 By controlling the current, the current is changed to the light emitting element (19a), and the optical output voltage Vp of the light receiving element (19b) is applied to the inverting input terminal of the operational amplifier (e), so negative feedback is applied. By this, control is made so that Vp=Vs.

This is because semiconductors are used for the light-emitting element and the light-receiving element, so the intensity of the light beam and the electromotive force of the light-receiving element usually fluctuate due to changes in ambient temperature, so a control circuit is formed to compensate for temperature dependence. This is hk.

Therefore, the photo ink club [phase] side and 7 Oto coupler 09
The temperature dependence of the light-emitting element 041 and the light-receiving element (+5a) i or (15b) of the photointerrupter 0 Enoki can also be corrected by placing them nearby and under the same temperature conditions. When the amount of displacement is at a constant position, the optical output of the light receiving element is +y
hi 1 weight 1 mu yen - present ≧ no 1/r yi -4 It becomes possible to obtain a stable output.

The optical output voltage eo is amplified by an amplifier ■ and the output is converted into a voltage output vI or a current output 1. If the signal is stopped and transmitted, a pressure sensor is obtained in which 'A (If) CcEψ (pressure difference Δp) is obtained.

Of course, in order to reverse the output VIcr)% due to the displacement of the light shielding plate, the light receiving element (15a) across the photointerrupter 0,
It goes without saying that the structure in which the polarity of both terminals in (15b) is 1 (inverted, but the photointerceptor is 2-pole) may be used by reversing the systems a and b in FIG.

FIG. 5 is an electric circuit diagram b based on another embodiment in which the photocoupler 09 and photointerrupter (19a) in the electric circuit of FIG. 2 are also used as light emitting elements α and (19a). show.

That is, the light-receiving element (19b) is placed within the light beam so that the light beam from the light-emitting element 0→ of the photo interrogator Q41 does not interfere with the light reception by the light-receiving element (tsa), (15b). iJ
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When the -y-Jk coupler is configured, the light emitting element (19a) in FIG. 2 becomes unnecessary, and the light emitting element α can also be used, and the electric circuit in FIG. 5 is eliminated.

Although the structure of the photointerrupter does not necessarily have to be differential, a differential type is more advantageous in consideration of the stability of the zero point at the neutral point in the displacement detection system. In other words, even if the photointeracitor (g) and the photocoupler α are installed close together, it is difficult to achieve completely equal temperature conditions either transiently or steadily. The main objective of the present invention is that even if the voltage is distorted, the output signal at the neutral point can maintain zero voltage.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal cross-sectional side view of a photointerrupter used in the device according to the present invention, Fig. 2 is an electrical circuit diagram of the device according to the invention for converting mechanical displacement into frost and air, and Figs. 3a and 3b are FIGS. 4a and 4b, which are schematic enlarged side views of the photointerrupter portion, are characteristic diagrams when the displacement by the photointerrupter is converted into an electrical signal. In the drawing, symbol (t), (2) is a diaphragm case, (3) is a diaphragm, (to) is a light shielding plate, a< is a light emitting element, (15)
a). (15b) is a light receiving element, (g) is a photo interrogator,
(The lamp is a photocoupler, (1) is a calculation tank middle device, and the spade is a widening device. Patent applicant: Seiryu Kogyo Co., Ltd. Figure 4b

Claims (1)

[Claims] A light-emitting element that emits parallel or nearly parallel infrared beams, two light-receiving elements installed close to each other on the side opposite to the optical axis, and a light-emitting element located at an intermediate position between the light-emitting element and the light-receiving element perpendicular to the optical axis. A light-shielding plate that is mechanically displaced in the direction of A photointerrupter mechanism for differentially converting the received light signals of 22 into electrical signals is provided, and a photocube 2 formed of a light emitting element and a light receiving element is provided near the photointerrupter. The light-emitting elements of Otokazura are connected in series or used in combination, so that the photovoltaic force generated in the light-receiving element of the photocoupler is constant.
A device that converts mechanical displacement into an electrical signal and includes an electronic circuit that controls the current flowing to the light-emitting element of a photointerrupter and photocoupler.