JPS6070326A - Pressure sensor - Google Patents

Abstract

PURPOSE:To facilitate design and to obtain high detection accuracy, by providing a diaphragm, which converts the change in pressure into mechanical displacement, and a light shielding plate, which is provided between a light emitting element and a light receiving element and is associatively linked with the operation of said diaphragm. CONSTITUTION:A diaphragm 111 can convert the change in pressure into mechanical displacement. A sealing projection part 112 is provided at the outer phriphery of the diaphragm 111. A diaphram plate 123 comprises a light shielding plate 121 having an opening hole 119 and a spring receiver part 120 and a diaphragm reinforcing plate 122 as a unitary body. The plate 123 is fixed to the diaphragm 111 vertically. One end of a spring 124 is fixed to the spring receiver part 120 of the diaphragm plate 123. In this case, the factor, which determines the operation of the diaphragm 111 with respect to the pressure change, is the rigidity of the spring 124. Therefore, designing work becomes easy and the high detection accuracy is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a pressure sensor that electrically detects changes in pressure.

2. Description of the Related Art Conventional Structures and Problems With the recent electronicization of various devices, there is an increasing need for electronic pressure sensors that can extract pressure as an electrical signal. In particular, it has become easy to perform high-performance signal processing using microcomputers, and low-cost and highly reliable pressure sensors are required for both industrial measurement and general use such as household appliances.

A conventional pressure sensor that converts the water level of a washing machine into pressure and electrically detects the change in pressure will be described below with reference to the drawings.

In Fig. 1, 1 is a spin-drying tank/washing tank, 2 is a water receiver, and 3 is a dehydration hole, and the water supplied to the spin-drying tank/washing tub 1 is passed through the dehydration hole 3.
It passes through and stays in water tray 2.

4 is an air trap chamber provided on the side of the water receiver 2; 6 is an air hose connected to the air trap chamber 4; 6 is a pressure sensor connected to the air hose 6; 7 is a motor; The pulsator 10 or the dehydration tub/washing tub 1 is rotated via a speed reduction mechanism or the like.

This pressure sensor 6 will be explained using FIG. 2, FIG. 3, and FIG. 4.

Reference numeral 11 denotes a diaphragm that converts pressure changes into mechanical displacement. Its outer periphery 12 is sealed by a lid 13 and a case 14, and an air chamber 16 is formed between the diaphragm 11 and the lid 13. Air inlet 1 in the lid 13
6 and a stopper 17 for the diaphragm 11 are provided, and an air hose shown in FIG. 1 is connected to the air inlet 16. Inside the case 14 is a pair of normally open contacts 18. A normally closed contact 19 is arranged and electrically connected to a normally open terminal 18a and a normally closed terminal 19a fixed to the case 14. The common contact 21 provided at the tip of the contact spring 20 is the normally open contact 18. The normally closed contacts 19 are disposed between the normally open contacts 18. It is cantilevered and fixed to the case 14 so as to be able to reciprocate between the normally closed contacts 19, and at the same time is electrically connected to the common terminal 21a. As shown in FIG. 4, the contact spring 20 is provided with a U-shaped hole 22, and an inner plate 24 having a long hole 23 located inside the U-shaped hole 22.
It consists of an outer plate 25 having a common contact point 21 located on the outside, and a quick-acting toggle spring 26 is installed between the inner plate 24 and the outer plate 25. On the diaphragm 11, there is a long hole 23 provided in the inner plate 24 of the contact spring 2o.
A diaphragm plate 29 is provided which has a drive groove 27 and a spring receiver part 28 which are fitted in the inner plate 24 to interlock the vertical movement of the diaphragm 11 and the inner plate 24. The spring receiver of the diaphragm plate 29 is provided with a spring 3o on the portion 28 that determines the operating ratio of the diaphragm 11 with respect to pressure, and is restricted in the rotational direction with respect to the case 14 and is slidable in the vertical direction. It is fixed with a cam 32 via. The cam 32 rotates around a shaft 33 fixed to the case 14, and the distance from the shaft 33 to the outer circumference of the cam 32 is set at 11, 12, 13, .
! 4 are different. By rotating the cam 32, the distance from the shaft 33 to the spring receiver 31-1 can be changed, and the amount of deflection of the spring 30 can be changed.
Compared to the force f1 generated on the diaphragm 11, if the force pressing the spring 3o toward the stopper 17 and the toggle spring 26 is large, the diaphragm plate 29 is stopped at the stopper 17 via the diaphragm 11. ,
The force f1 generated in the pressure P and the diaphragm 11 is
When the force of pressing the spring 3o and the toggle spring 26 toward the stopper 17 becomes greater, the diamond slam plate 2
9 starts moving. After that, since the moving distance of the diaphragm plate 29 is proportional to the pressure P, the pressure P at which the diaphragm plate 29 starts moving can be detected in multiple stages by manually operating the cam 32.

In addition, pressure sensors used in washing machines etc. have a pressure of 600ttaH2.
In order to detect low pressures below 0, the diaphragm 11 is made of a material such as rubber and has a thin plate, and is configured to operate sensitively even to slight pressure changes.

Next, a water level detection operation of a washing machine using the conventional pressure sensor configured as described above will be explained.

The overall outline will be explained using Figure 1. Before washing, the water level of the pressure sensor 6 is set in advance according to the amount of laundry. Then, when water is supplied to the water receiver 2 of the washer a', the air trap chamber 4. The air within the air hose 5 is compressed according to the water level. A pressure sensor 6 detects this air pressure.

Next, the operation of this pressure sensor 6 will be explained. First, if the pressure is atmospheric pressure, as shown in Figure 2, the diaphragm plate 29
The spring 30 is connected to the stopper 17 via the diaphragm 11.
．． It is pressed by the toggle spring 26, and the contact spring 20
The common contact 21 provided on the external plate 26 is the normally closed contact 19
is in contact with and is off. Threading contact spring 2o
The inner plate 24 is pressed by the spring 30 and is located closer to the diaphragm 11 than the outer plate 25, so that the toggle 0 bit 6
Therefore, the common contact 21 of the outer plate 26 presses against the normally closed contact 19.

Thereafter, when the water level increases and reaches a certain pressure P1, the diaphragm plate 29 starts moving. As the water level further increases, the outer plate 25 of the contact spring 2o. Toggle spring 26. Internal plate 24
becomes horizontal, and when the pressure finally reaches P2, the inner plate 24 of the contact spring 20 is moved from the outer plate 25 of the contact spring 20 as shown in FIG.
is located on the cam 32 side, the toggle spring 26 rapidly presses the outer plate 25 toward the diaphragm 11 side, and the outer plate 25
The common contact 21 provided at the tip of the contact 18 contacts the normally open contact 18 and turns on. Even if the water level is further increased, it will remain in this on state.

Next, to explain the case of drainage, when the water level is above the pressure 22, the normally open contact 18 and the common contact 21 are in contact and remain in the on state, as in the case of water supply, and further water is drained, and the pressure is reduced to P2. Maintain this state even if it becomes less than 171
When the water pressure reaches Pl, the inner plate 24 of the contact spring 2o
is located closer to the diaphragm 11 than the outer plate 25, so
The toggle spring 26 rapidly presses the outer plate 25 toward the cam 32, and the common contact 21 contacts the normally closed contact 19 to turn off, and maintains this off state even when water is drained. .

FIG. 6 shows an exit view obtained by this pressure sensor. The A line is an output diagram for increasing pressure, and the open line is an output diagram for decreasing pressure. The pressure sensor 6 of the washing machine is configured to detect point P2 and stop water supply. P2 is determined by the user according to the amount of laundry, and the detected pressure P2 can be changed by rotating the cam 32.

In addition, the difference between Pl and P2 is largely influenced by the toggle spring 26, and when water is supplied at a constant rate, the diaphragm plate 29 is moved to the stopper 1.
This is because the force that presses the diaphragm plate 29 toward the cam 32 side acts when draining water.

However, such a configuration has the following problems.

(1) Since the toggle spring 26 is used for quick-acting detection, the pressure sensor obtains information as to whether the maximum value of the measured pressure has reached the set pressure or higher. As shown in Figure 6, detection point P2 during water supply and detection point P1 during drainage
Since the difference in P1 is large, once it is turned on, the P1
Even if the pressure decreases between P2 and P2, it remains on, making it unsuitable for use as a pressure sensor 6 that detects pressure that changes up and down every moment. In addition, if such a contact type pressure sensor 6 is configured without the l/gle spring 26, the contact state of the common contact 21 with the normally open contact 18° and the normally closed contact 19 will become unstable due to external vibration, etc. There was a problem of false detection.

(2) The factors that determine the operating ratio of the diaphragm 11 with respect to the change in pressure to be detected are multiple points such as the rigidity of the spring 3o, the rigidity of the toggle spring 26, the rigidity of the internal plate 24 of the contact spring 2o, and the rigidity of the diaphragm 11. In addition to making the design complicated and difficult, the variation in rigidity between each component accumulates, which increases the variation in characteristics between pressure sensors and deteriorates detection accuracy.

(3) In a configuration in which the pressure sensor 6 is connected to a microcomputer, the common contact 21. Normally open contact 18. When the normally closed contact 19 was oxidized, a stable connection state could not be obtained. Therefore, each of the contact points requires gold or silver plating with good oxidation resistance, resulting in high costs.

(4) Common contact 21 is normally closed contact 19. Since it is configured to move between normally open contacts 18, a space is always required between each contact, so water droplets, steam, etc. can easily enter, and false detection may occur if water droplets or foreign objects come into contact with each contact. Yes, the usage environment range was limited.

Purpose of the Invention The present invention was developed in view of the above-mentioned drawbacks of the conventional technology, and has a function that can automatically detect multiple levels of pressure and pressure range information as electrical signals, has good followability to pressure fluctuations, and has high detection accuracy. The present invention provides a pressure sensor that has high resistance to water and can be used even in a water-resistant environment. .

Structure of the Invention The present invention includes a light-emitting element, a light-receiving element that receives light from the light-emitting element, a diaphragm that converts a change in pressure into mechanical displacement, and a diaphragm that operates in conjunction with the operation of the diaphragm to connect the light-emitting element and the light-receiving element. A light shielding plate provided between the light shielding plate and a spring that determines a mechanical displacement ratio of the diaphragm with respect to a change in the pressure, the light emitted from the light emitting element is directed to a position of the light shielding plate that is linked to the movement of the diaphragm. It is configured to pass or block light from the light emitting element toward the light receiving element, and the pressure value is determined based on whether or not the light receiving element receives a certain amount or more of the light emitted from the light emitting element.

DESCRIPTION OF EMBODIMENTS A case where a pressure sensor according to an embodiment of the present invention is used to detect the water level of a washing machine will be described below with reference to the drawings.

FIG. 6 is a sectional view of a main part of a washing machine using a pressure sensor according to a first embodiment of the present invention. Note that the same numbers are given to the same members as in the conventional example. 1 is a dehydration tank and washing tank, 2 is a water receiver, and 3 is a dehydration hole.

4 is an air trap chamber, 6 is an air hose, 7 is a motor, 8 is a belt, 9 is a mechanical case with a built-in deceleration mechanism, etc., a pulsator, and 1oo is a pressure sensor according to the first embodiment of the present invention.

Next, this pressure sensor ioo will be explained using FIGS. 7, 8, and 9.

In Figures 7 and 8, 111 is a diaphragm that converts pressure changes into mechanical displacement.It is made of a material such as rubber and has a thin plate thickness in order to operate sensitively even with slight pressure changes. I am using it. A convex portion 112 for sealing is provided on the outer periphery of the diaphragm 111, and the lid 113 and the case 114 are caulked and sealed with a caulking ring 115.
6 is formed. The lid 113 has an air inlet 117
A stopper 118 is provided to limit the downward movement of the diaphragm 111. The diaphragm 111 has a light shielding plate 12 having an opening hole 119 and a spring receiver part 120.
1 and a diaphragm reinforcing plate 122 are fixed vertically. The spring bearing of this diaphragm plate 123 is a part 12oKJj: The spring 12 determines the operating ratio of the diaphragm plate 123 with respect to pressure.
4 is installed, and the other end is fixed by a cam 126 via a spring receiver 126 that is slidable in the direction of expansion and contraction of this spring 124. The cam 126 rotates around a shaft 127 fixed to the case 114, and the diaphragm plate 1 responds to pressure.
In order to switch the operating ratio of 23 into four stages, the distance from the shaft 127 to the outer periphery is set to tl +t2 +'31t4.

Further, a pair of light emitting element 128 and light receiving element 129 are fixed facing each other with the light shielding plate 121 in between. Case 11
Opening portions 130 and 131 are provided on the front surfaces of the light emitting element 128 and the light receiving element 129 of No. 4, respectively. The terminal portions (not shown) of the light emitting element 128 and the light receiving element 129 can be electrically insulated by resin molding or the like after connecting lead wires or the like. The diaphragm plate 123 is the case 1
It is slidably provided on a bearing part 132 provided in 14. A hole 133 is provided in the case 114 so that the back side of the diaphragm 111 is always at atmospheric pressure. Therefore, the operating ratio of the diaphragm plate 123 with respect to pressure changes is determined by the rigidity of the spring 124, the rigidity of the diaphragm 111, and the sliding frictional resistance of the diaphragm plate 123. However, since the rigidity and sliding frictional resistance of the diaphragm 111 are very small, the spring 124 stiffness.

Next, a water level detection operation of a washing machine using the pressure sensor 100, which is the first embodiment of the present invention configured as described above, will be described.

Before washing, the water level of the pressure sensor 100 is set in advance according to the amount of laundry. When water is supplied to the water receiver 2 of the washing machine, air trap chamber 4. The air in the air hose 5 and the air chamber 116 of the pressure sensor 100 is compressed according to the water level. This air pressure change is converted into a mechanical displacement by the diaphragm 111, and this mechanical displacement is further converted into an electrical signal to detect whether the set water level has been reached or whether it is within the set water level range.

Next, the operation of the pressure sensor 10Q at this time will be explained in detail.

First, when the water level in the water tray 2 is zero, as shown in Figure 7,
The diaphragm plate 123 is pressed against the stopper 118 via the diaphragm 111 by a spring 124. In this state, the light from the light emitting element 128 is transmitted to the light shielding plate 12.
1, the light does not reach the light receiving element 129, and the off state is detected.

As shown in FIG. 8, the height in the axial direction of the light shielding plate 121 of the opening 131 provided on the front surface of the light receiving element 129 is h, and the end face A of the diaphragm plate 123 is set as a reference. The distance from the end surface B of the opening hole 119 provided in the light shielding plate 121 to the end surface B is set as xl, the distance from the end surface A to the end surface C of the opening hole 119 is set as x2, and the bent end surface B
When the distance from to the end surface C is d, the displacement
The amount of light received at No. 9 is as shown by line A in FIG. 9A. In other words, when water is supplied and the pressure exceeds Pl, the diaphragm plate 12
3 begins to rise. When the elbow pressure reaches P2, the opening hole 119 of the light shielding plate 121 and the opening 131 on the front surface of the light receiving element 129 begin to overlap, and the light emitted from the light emitting element 129 passes through the opening 130.
It passes through the opening hole 119 and the opening 131, and the light receiving element 129
starts receiving light.

When water is further supplied and the pressure exceeds P3, the overlapping area of the opening hole 119 of the light shielding plate 121 and the opening 131 on the front surface of the light receiving element 129 (hereinafter referred to as the light passing area) increases.
When the amount of light received in No. 29 exceeds the threshold value, it is determined that the light is on. By associating this pressure P3 with a water level determined in advance by the user according to the amount of laundry, it becomes possible to detect the water level desired by the user.

Furthermore, when water is further supplied and the pressure increases from P3, the light passage area increases until pressure P4, and from pressure P4 to pressure P5.
Up to this point, the light passing area is at its maximum value, and when the pressure reaches 26 or more, the light passing area begins to decrease, and when the pressure exceeds P6, it becomes below the threshold value, and an OFF determination is made. In this way, the pressure P0 to P3 is judged to be off, and the pressure P3 to P4 is determined to be off.
Until then, it is determined to be on, and when the pressure exceeds P6, it is determined to be off.

Tsu1suP. It is possible to detect pressures P3 and P4 in the process in which the pressure increases from the point of , or in the process in which the pressure decreases from pressure 26 or higher, and it is also possible to detect whether the pressure is within P3 to P6. be.

Furthermore, if you want to detect multiple levels of pressure, rotate the cam 126 and adjust 11, 12, 13, and 14.
By changing the amount of deflection of the spring 124 and adjusting the force that presses the diaphragm 111 against the stopper 118,
It is possible to change the value of the pressure P2 at which the diaphragm plate 123 starts moving, and it becomes possible to move the γ-rays and the a-rays in FIGS. 9A and 9B in parallel.

Moreover, by changing the position of the opening hole 119 of the light shielding plate 121, the pressure can be reduced to P. -P3 always receives the light from the light emitting element 128 to the -'N- youngest child 129 described in 1. It is also possible to detect the pressure P3 by arranging the sensor to receive light above a threshold value, so that when the pressure becomes 23 or above, the pressure becomes below the threshold value.

As described above, according to this embodiment, the following effects can be obtained.

(1) Unlike conventional contact contact methods, all electrical contact parts can be electrically insulated by resin molding, etc., and have good water and moisture resistance, expanding the range of environments in which they can be used.

(2) Since the element that determines the operating ratio of the diaphragm 111 with respect to pressure changes is mostly the stiffness of the spring 124, the design is easy, the variation in characteristics between pressure sensors can be reduced, and high precision can be achieved. Detection accuracy can be obtained.

(3) Hysteresis of conventional pressure sensor is 100mmH
2O, whereas in this example the hysteresis was 2O.
It can be used in environments where the pressure fluctuates rapidly as it can hold down to about mmH2O.

(4) There are fewer components than before, so the cost is lower than before.

The number of assembly steps is reduced, resulting in an inexpensive pressure sensor.

Next, a pressure cell according to a second embodiment of the present invention will be described with reference to FIGS. 10, 11, and 12.

In FIGS. 10 and 11, 211 is a diaphragm that converts pressure changes into mechanical displacement.
A convex portion 212 for sealing is provided on the outer periphery of the lid 213.
and the case 214 are crimped and sealed by a crimping ring 215, and the diaphragm 211 and the lid 213
An air chamber 216 is formed between them. The lid 213 is provided with an air inlet 217 and a stopper 218 for regulating the lowering limit of the diaphragm 211.

This diaphragm 211 has an opening hole 219a.

A diaphragm plate 223, which is formed by integrating a light shielding plate 221 having spring receivers 219b, 219c, and 219d and a diaphragm reinforcing plate 222, is fixed vertically. One end of a spring 224 that determines the operating ratio of the diaphragm plate 223 with respect to pressure is installed in the spring bearing part 220 of this diaphragm plate 223, and the other end is installed in the case 214.
The spring 224 is attached to the
It is fixed by an adjustment screw 226 that adjusts the amount of deflection.

Further, the three pairs of light emitting elements 228a and the light receiving element 229a are fixed to the case 214 at intervals greater than the maximum movement distance of the diaphragm 211.

Light emitting elements 228a and 228b of the case 214.

228C has openings 230a and 230b on the front side, respectively.
.

The front surfaces of the 230C input light receiving elements 229a, 229b, and 229c have openings 231a, 231b, respectively.
231c is provided. A hole 23 is provided in the case 214 so that the back side of the diaphragm 211 is always at atmospheric pressure.
3 is provided.

Next, the operation of the pressure sensor according to the second embodiment of the present invention constructed as above will be explained in detail.

First, when the air chamber 216 is at atmospheric pressure, the diaphragm plate 223 is pressed against the stopper 218 by the spring 224 via the diaphragm 211, as shown in FIG. In this state, the light emitting elements 228a, 228b,
The light from 228c is blocked by the light shielding plate 221, and the light from the light receiving elements 229a and 229b.

229C is not reached and the off state is detected.

As shown in FIG. 11, light receiving elements 229a, 229b
.

Openings 231a provided on the front surface of 229C
.

The height of the light shielding plates 221 of 231b and 231c in the axial direction is h, and the end face A1.
A2. Spring 224 of opening holes 219a, 219b, 219c provided in light shielding plate 221 based on A3
The side end faces are B1. B2. B3. B4, the lower end surface is C1, C2, C3, C4 and the waist A1 to B1 is Xl
.

A2 to B2 x2. A1 to C1 x3. A3 to B
3 x4. A1 to B4 x5. A2 to C2 x6.
A1 to C4 x7. Assuming that A3 to C3 is x8, the moving distance of the diaphragm plate 223 relative to the pressure is the pressure P as in the first embodiment.

It remains in a stopped state from P1 to P1, and when the pressure exceeds P1, it moves in proportion to the increase in pressure.

When the pressure changes from Po to Pl 1, the diaphragm plate 223 is stopped, and the light emitted from the light emitting elements 228a, 228b, and 228c is blocked by the light shielding plate 221, and the light emitted from the light receiving element 229
A, 229b, and 229c do not receive light and are in an off state.

When the pressure is between B2 and B3, only the light emitted from the light emitting element 228a passes through the opening hole 219a of the light shielding plate 221.
The light receiving element 229a receives light and turns on. If the pressure is further increased and the diaphragm plate 223 moves, the output waveform of the light receiving element 229a becomes the line of force in FIG. 12A, the output waveform of the light receiving element 229b becomes the line of force in FIG. The output waveform becomes the horizontal line C in Fig. 13, and the on state is 1 and the off state is O, and the signal codes at the pressures P0 to P9 of the light receiving elements 229a, 229b, 229c are as shown in Fig. 12, and there are 3 pairs. light reception.

In the case of a light emitting element, it is possible to detect eight levels of pressure based on the square of 3. In addition, in FIG. 12, the threshold value of the light-receiving element is assumed to be ◯. In this embodiment, there are three pairs of light receiving units 2.
Although the explanation has been made using light emitting elements, it goes without saying that the optimum number may be one depending on the application, whether it is two pairs or four pairs.

As described above, this embodiment has the following effects.

(1) It is possible to detect absolute pressures equal to the square of the number of light emitting and light receiving element pairs, and multiple levels of pressure can be automatically detected. It's 0. Since the pressure is sent out as a single digital signal, microcomputer processing becomes easier.

(2) Connect the light shielding plate 221 and spring 224 to the diaphragm 2
11, so the up and down reciprocating movement of the light shielding plate is smooth.

(3) By installing the light shielding plate 221 and the spring 224 in series, the outer diameter size can be made extremely small, the degree of freedom in the installation location is increased, and the material cost can be reduced.

Next, regarding the pressure sensor which is the third embodiment of the present invention,
This will be explained using FIGS. 13, 14, and 15.

In FIGS. 13, 14, and 16, 311 is a diaphragm that converts changes in pressure into mechanical displacement, and a convex portion 312 for sealing is provided on the outer periphery of this diaphragm 311. It is caulked and sealed by a caulking ring 315, and the diaphragm 311
An air chamber 316 is formed between the lids 313. Lid 3
13 is provided with an air inlet 317 and a stopper 318 for regulating the lowering limit of the diaphragm 311. The diaphragm 311 has opening holes 319a, 3
A light shielding plate 321 having 19b, 3190, and 319d;
A diaphragm plate 323 is fixed to the spring receiver, which is integrated with a diaphragm reinforcing plate 322 having a recess 320 in the center thereof. The light shielding plate 321 is the diaphragm reinforcing plate 32
It is fixed vertically at a position offset from the center of 2.

The spring receiver of this diaphragm reinforcing plate 322 has a recess 320.
One end of a spring 324 that determines the operating ratio of the diaphragm plate 323 with respect to pressure is fixed to the case 31, and the other end is fixed to the case 31.
It is fixed by an adjustment screw 326 that adjusts the amount of deflection of the spring 324 via a spring receiver 325 provided at the spring 324.

In addition, three pairs of light emitting elements 328a, light receiving elements 329a and light emitting elements 328b, light receiving elements 329b and light emitting elements 3280
The position of the light receiving element 329C is regulated on a plane parallel to the diaphragm 311 by a light emitting element holder 334 and a light receiving element holder 335 provided with an elongated opening 331, facing each other with the light shielding plate 45 interposed therebetween.

Note that holes 333 are formed in the printed circuit board 336 and the case 314 so that the back side of the diaphragm 311 is always at atmospheric pressure.
is provided.

FIG. 16 is a side view of the light shielding plate 321 in front of the light receiving elements 329a, 329b, and 329c when the air pressure in the air chamber 316 is atmospheric pressure. x up to the upper end of 319a
l, X2 up to the upper end surface of opening hole 319b, opening hole 3
X3 up to the lower end surface of 19a, x4 up to the upper end surface of opening hole 319C + X5 up to the upper end surface of opening hole 319d
, up to the lower end surface of the opening hole 319b x6° opening hole 319d
Assuming that the distance to the lower end surface is X-r, and the distance to the lower end surface of the opening hole 319C is x8, the output for each pressure of this pressure sensor is as shown in FIG. 12 a, b, c, as in the case of the second embodiment.
It becomes like d.

As described above, according to this embodiment, the following effects can be obtained.

(1) Since the spring 324 and the two light-receiving and light-emitting element groups are arranged in parallel, the device can be made thinner, easier to install in a space-limited location, and material costs can be reduced.

(2) In the second embodiment, there are multiple openings on the front surface of the light-receiving element group, so there are multiple criteria for determining the distance to the opening in the light-shielding plate, but in this embodiment, there is only one criteria. That's all,
Dimensional accuracy is improved and dimensional control is also easy.

(3) The shape of the mold for forming the opening is simplified,
Man-hours for manufacturing can be reduced.

Next, regarding the pressure cell which is the fourth embodiment of the present invention,
This will be explained using FIGS. 16 and 17.

The configuration is almost the same as the third embodiment shown in FIGS. 13, 14, and 15. The difference from the third embodiment is as follows:
Three light emitting elements 428a are placed at the focal point of the three light receiving elements 429.
, 428b, 428c are oriented on the same plane parallel to the darf yaphram 411,
Accordingly, the light shielding plate 421 and the opening 431 have an arc shape.

With this configuration, in the third embodiment, the light emitting element can detect multiple levels of absolute pressure even when the light emitting element is constantly lit or pulsed; however, in this embodiment, the light emitting element 428a,
428b and 428c are turned on with a pulse, and the light receiving element 429
By scanning which light emitting element receives the light, multiple levels of absolute pressure can be detected.

Furthermore, it goes without saying that the number of light emitting elements may be one and the number of light receiving elements may be plural.

As described above, according to this embodiment, the number of light-receiving elements or light-emitting elements used can be reduced, making it possible to significantly reduce costs.

In addition, 1. Second. Third. Although positive pressure was explained in the fourth embodiment, it goes without saying that similar results can be obtained with negative pressure.

Effects of the Invention As is clear from the description of the above embodiments, the present invention has good ability to follow up and down fluctuations in pressure, can detect multiple pressure ranges and absolute pressure, and has excellent environmental resistance. It is possible to provide a good and inexpensive pressure sensor.

[Brief explanation of the drawing]

Figure 1 is a side sectional view of the main parts of a washing machine using a conventional pressure sensor, Figure 2 is a sectional view showing the normally open contact of the conventional pressure sensor in an open state, and Figure 3 is a normally open contact. 4 is an enlarged plan view of the same main part, FIG. 6 is a diagram showing the relationship between pressure and output of the same pressure sensor, and FIG. 6 is a pressure sensor that is an embodiment of the present invention. FIG. 7 is a cross-sectional view of the pressure sensor according to the first embodiment of the present invention; FIG. 8 is an enlarged cross-sectional view of the main part of the light-receiving element of the pressure sensor; Figure 9A is a diagram showing the relationship between the displacement of the light shielding plate and the output of the same pressure sensor, Figure 9B is a diagram showing the relationship between the pressure of the same pressure sensor and the displacement of the light shielding plate, and Figure 10 is a diagram showing the relationship between the displacement of the light shielding plate and the output of the same pressure sensor. A cross-sectional view of a certain pressure sensor, Fig. 11 is an enlarged cross-sectional view of the main part of the light-receiving element of the same pressure sensor, Fig. 12 A, B, C, 'D is an output diagram of each light-receiving element in response to pressure changes, and Fig. 13 14 is a cross-sectional view of a pressure sensor according to a third embodiment of the present invention, FIG. 14 is a C-B-C cross-sectional view of FIG. 13, and FIG. 15 is an enlarged side view of a main part of the light receiving element of the pressure sensor , FIG. 16 is a sectional view of a pressure sensor according to a fourth embodiment of the present invention, and FIG. 17 is a cross-sectional view of a pressure sensor according to a fourth embodiment of the present invention.
FIG. 6 is a sectional view taken along line C-B-C in FIG. 6; 111, 211. 311. 411...Da/1 Yafram, 121,221,321,421...
... Light shielding plate, 124, 224, 324, 424...
...Spring, 128.228,328,428...-Light emitting element, 129.229,329,429... Light receiving element. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 4
Figure 5 P Figure 7 Figure 8 f') f (14 Figure 9 p6 p7 P6
PrFigure 13Figure 14Figure 15

Claims (1)

[Scope of Claims] (1) A light-emitting element, a light-receiving element that receives light from the light-emitting element, a diaphragm that converts changes in pressure into mechanical displacement, and a light-emitting element provided between the light-emitting element and the light-receiving element. A pressure sensor comprising: a light shielding plate interlocked with the movement of the diaphragm; and a spring determining a mechanical displacement ratio of the diaphragm with respect to a change in the pressure. (2) The pressure sensor according to claim 1, wherein there are a plurality of pairs of light receiving elements and light emitting elements. (3) The pressure sensor according to claim 2, wherein the light receiving element and the light emitting element are arranged in parallel in the axial direction of the diaphragm. (4) The pressure sensor according to claim 2, wherein the light receiving element and the light emitting element are arranged in parallel perpendicularly to the axial direction of the diaphragm. (6) The pressure sensor according to claim 1, wherein the optical axes of the plurality of light emitting elements are directed toward one light receiving element.