JP2884793B2 - Light switch - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical switch for transmitting a signal via an optical fiber, such as a push button switch and a limit switch.

[0002]

2. Description of the Related Art An optical switch has noise resistance, environmental resistance,
In recent years, they have been widely used for signal transmission, sensing, measurement, and the like in the so-called FA field because of their excellent insulation resistance and the like. Some conventional optical switches have a light emitting function in the optical switch body and some do not. Of these, those that do not have a light emitting function usually have two optical fibers for transmitting and receiving optical signals, and one optical fiber receives light from the outside, and this light is detected by the switch body. The light signal is light-blocked or modulated according to the above, and is sent out from the other one. On the other hand, a switch having a light emitting function has a built-in battery in the switch, and the light emitting element is caused to emit light by the battery in response to an operation input or a detection input signal, and is transmitted to an optical fiber. Here, a lithium battery is generally used as the battery, but a solar cell and a capacitor may be used in combination.

[0003]

Incidentally, among the above-mentioned conventional optical switches which do not have a light-emitting function, they always have to have two optical fibers, which makes wiring complicated and costly. Also increase. In the case of a device having a light emitting function, only one optical fiber is required to be connected. However, there is a trouble that a spent battery must be replaced each time or periodically.
Similarly, even when using solar cells that do not need to be replaced,
There is a problem that it is not always sufficient in terms of securing sunlight, deteriorating power generation capacity, and lack of capacity when operating frequently. SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to reduce the number of optical fibers to be connected to one.
Another object of the present invention is to provide an optical switch that is inexpensive and easy to maintain without requiring replacement of batteries.

[0004]

In order to achieve the above-mentioned object, the invention according to claim 1 includes a piezoelectric element and a leaf spring.
A pressurizer that operates by the external pressure applied to press the piezoelectric element while resisting the spring force of the coil spring, and a light emitting element that is connected to the piezoelectric element and emits light by the voltage generated by the piezoelectric element and sends out an optical signal to the optical fiber And a leaf spring.
When the magnitude of the external pressure applied to the plate exceeds a certain value, the leaf spring
When the direction of force is reversed, the pressurizer
The element is pressurized, and the pressurizing element repelled by the coil spring is
And the piezoelectric element is reciprocated a plurality of times between the piezoelectric element side and the piezoelectric element side to press the piezoelectric element a plurality of times. According to a second aspect of the present invention, in the first aspect, a capacitor is connected in parallel to the piezoelectric element and the light emitting element. According to a third aspect of the present invention, in the second aspect of the present invention, a switch circuit that closes when the charging voltage of the capacitor rises to a predetermined value is connected in series to the light emitting element.

[0005]

According to the first aspect of the present invention, the push button
By pressing the leaf spring more, the leaf spring is reversed
The pressurizing element is driven (struck) toward the piezoelectric element, and the pressure from the pressure receiving plate is reduced.
The pressurizing element is returned by the force to invert the leaf spring again.
After that, the restoring force of the coil spring and the reaction from the leaf spring and the pressure receiving plate
Pressing the piezoelectric element multiple times by reciprocating the pressurizer with force
Then, a pulse-like voltage is generated. The light-emitting element emits light by this voltage and sends an optical signal to the optical fiber. Claim
In the invention described in 2 , the piezoelectric element and the light emitting element
Generated from the piezoelectric element to the capacitor connected in parallel
Is charged, and then the light-emitting element is discharged by discharging the electric charge.
Emits light. According to the third aspect of the present invention, a capacitor is provided.
When the charging voltage of the LED rises to a predetermined value,
The switch circuit connected to the row closes, and the light emitting element emits light
I do.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing a part of an embodiment in which the invention described in claim 1 is applied to a push button switch. FIG. 2 is an operation explanatory view of the embodiment according to the first aspect of the present invention.

In FIG. 1, a push button 2 is inserted into an opening 1a at the top of a housing 1. A coil spring 3 is mounted on the large diameter portion formed in the middle of the opening 1a, and urges the push button 2 upward through the flange 2a. A leaf spring 4 having a convex upper part and curved and fixed is fixed above the inside of the housing 1. The upper surface of the central part of the leaf spring 4 is arranged in contact with the lower end surface of the push button 2 or with a slight gap therebetween. A pressurizing element 5 is provided below the leaf spring 4.
Is disposed, and a piezoelectric element 7 is disposed below the pressure receiving plate 6 via a pressure receiving plate 6. A coil spring 8 is mounted between the upper surface of the pressure receiving plate 6 and the flange portion 5a of the pressure
Is pressed upward to keep the upper end of the pressure element 5 pressed against the lower surface of the leaf spring 4. The elastic force of the coil spring 8 is set relatively weak, and the leaf spring 4 is not excessively pressed. In addition, as the piezoelectric element 7, a piezoelectric element having a multilayer structure in which several tens of elements are stacked can be used.

In this state, when the push button 2 is pressed by a finger or the like with an external pressure from above, the push button 2 moves downward while compressing the coil spring 3 and presses the leaf spring 4 downward. When pressed, the leaf spring 4 descends while resisting the spring force, and curves downward while pressing the lower pressurizer 5. When the leaf spring 4 descends by a predetermined amount and passes through the reversing position, the direction of the spring force is reversed, and the pressing force of the pressurizer 5 is suddenly started by the spring force generated in the leaf spring 4 itself. As a result, the pressurizing element 5 is rapidly pressurized, and the lower end portion of the pressurizing element 5 strikes the upper surface of the pressure receiving plate 6 vigorously. At this time, the coil spring 8 is also compressed. However, since the spring pressure is weak, the resistance when the pressurizer 5 descends hardly occurs. After hitting the pressure receiving plate 6, the pressurizing element 5 is repelled and rebounds upward.
Further, the pressure receiving plate 6 is pushed downward and hits the pressure receiving plate 6. Since what
After being bounced once, the momentum stops and the upper surface of the pressure receiving plate 6
Settles in a state pressed by. With these operations, the pressure
The electric element 7 is intermittently impacted from the pressurizer 5 via the pressure receiving plate 6.
And a voltage is generated at both ends .

The voltage generated across the piezoelectric element 7 is shown in FIG.
Is applied to the light emitting diode 9 which is a light emitting element as shown in FIG. When the light emitting diode 9 emits light, the light enters the optical fiber 11 and is sent as an optical signal to a light receiving element 12 such as a distant photodiode. Light receiving element 1
2 is amplified by an amplifier 13 and sent to an operation detection circuit 14 such as a so-called transceiver. When the operation detection circuit 14 receives the detection signal,
The signal state is held until the next return signal is input, and the signal is appropriately amplified and output to the terminal 15. That is,
The piezoelectric element 7 outputs an optical signal only when the push button 2 is pressed, and thereafter, no optical signal is output while the push button 2 is kept pressed. Therefore, the operation detection circuit 14 keeps the state of the detected signal and continues the output. Although a load or the like operated by an optical switch is connected to the terminal 15, the state of the optical switch may be transmitted to a higher-order system via the terminal 15. Further, a pilot lamp indicating the state of the optical switch may be added to the operation detection circuit 14 as needed. This type of push button switch is used for an emergency stop button or the like that needs to hold a detected value. Similarly, limit switches have a purpose of holding a detection value, and this type of switch can be used for them.

In FIG. 1, the leaf spring 4 is bent downward and inverted when the push button 2 is pressed, but keeps the inverted state even after the push button 2 is raised and returned. Therefore, although not shown, the push button 2
A mechanism is provided for forcibly restoring the curvature of the leaf spring 4 when is pressed again. Further, as another mechanism, a mechanism that returns the leaf spring 4 by another return operation other than the operation of pressing the push button 2 again may be used. Further, the light emitting diode 9 shown in FIG. 2 may be attached to the housing 1 of FIG. 1 or may be provided separately from the housing 1.

FIG. 3 is a graph showing the relationship between the amount of movement of the push button 2 when the push button 2 is depressed in FIG.
7 is a graph showing a stroke of the piezoelectric element 7 and a change in stress applied to the piezoelectric element 7. Push button 2 as shown
Is pressed, the pressure element 5 also starts to move, but before the push button 2 reaches the final position, the pressure element 5 is accelerated and reaches the final position. Thereafter, the pressurizing element 5 repeats bouncing, and finally settles at the lower end position of the stroke. Further, stress is generated only when the pressurizer 5 is located at the lower end of the stroke, and while the presser 5 repeats bouncing, the generated stress is intermittent, and as a result, pulse-like stresses a to d are generated. Occur. The magnitude of the generated stress is maximum at the beginning and then gradually decreases thereafter.
Becomes constant after the stop of. As described above, when the push button 2 is pressed, the external force applied to the push button 2 is not directly applied to the piezoelectric element 7, but the shock is repeatedly applied to the piezoelectric element 7 after the snap action of the leaf spring 4. With this configuration, a substantially constant pattern of pulse-like stress is always applied to the piezoelectric element 7 from the pressurizer 5 without being significantly affected by the pressing speed or pressing force of the push button 2.

Further, since an impact is intermittently applied to the piezoelectric element 7 from the pressurizing element 5, the pressure from the piezoelectric element 7 is reduced compared with the case where a load is gradually applied from the pressing element 5 to the piezoelectric element 7 with the same force. Conversion to voltage is performed efficiently. Further, since the light emission signal is sent as an intermittent pulse-like intermittent pattern, the signal detection in the operation detection circuit 14 is further ensured.

FIG. 4 is a circuit diagram showing an embodiment according to the second and third aspects of the present invention. Figure 5 is likewise claim 2
4 is a graph illustrating the operation of the embodiment of the invention described in FIGS.

In FIG. 4, a capacitor 16 is connected in parallel to the piezoelectric element 7, and the charge generated from the piezoelectric element 7 is charged into the capacitor 16 via the diode 17. Here, the diode 17 may be omitted. Further, a series circuit including a light emitting diode 9 and a switch circuit 18 such as a varistor is connected in parallel to the capacitor 16, and when a charge is accumulated in the capacitor 16 and its terminal voltage rises to a predetermined level, the switch circuit 18 is turned on. The electric charge which is closed and stored in the capacitor 16 is supplied to the light emitting diode 9. When the energized light emitting diode 9 emits light, the emitted light enters the optical fiber 11 and is sent out as an optical signal. The charge Q stored in the capacitor 16
And the capacitance C and the voltage V of the capacitor 16 are:
As is well known, it is expressed as Q = C × V. The capacitance C includes the internal capacitance of the piezoelectric element 7 itself.

The specific operation of this embodiment is as shown in FIG. The fluctuation of the capacitor voltage V in FIG. 5 corresponds to the case where the pulsed stresses a to d shown in FIG. The voltage V gradually increases due to the generation of the pulse-like stresses a and b. When the voltage V reaches the voltage Va, the switch circuit 18 is closed, and the electric charge stored in the capacitor 16 is discharged. Thus, the current I is supplied to the light emitting diode 9. As a result of the discharge, when the voltage of the capacitor 16 falls to Vb, the switch circuit 18 recovers and opens, stops discharging, and returns to a standby state for charging. Next, the voltage V rises again due to the generation of the pulse-like stresses c and d, and the discharge is started again when the voltage V reaches the voltage Va.
In the embodiment, the discharge is performed twice by the operation of pressing the push button 2 once. As described above, since the generated charge from the piezoelectric element 7 is sequentially accumulated and then the discharge, that is, light emission is performed, even if the amount of charge generated from one pulse-like stress is small, the charge reaches the operating voltage of the switch circuit 18. By accumulating the electric charge, the peak current Ic supplied to the light emitting diode 9 can be increased. By changing the setting of the operating voltage Va of the switch circuit 18, the peak current Ic can be changed to a desired value.

When the optical switch sends an optical pulse to the optical fiber 11, the intensity of the optical pulse is more important than the length of the optical pulse, that is, the light emission time. It is. Therefore, as shown in the embodiment, by accumulating the generated charges in the capacitor 16 and increasing the voltage to discharge instantaneously, the peak current Ic is increased to increase the light emission amount of the light emitting diode 9, and the high quality light pulse Can be generated and sent. Also,
When the generated charge of the piezoelectric element 7 is small, the voltage V and the capacitance C of the capacitor 16 are inversely proportional to each other, as described above. It is possible to increase V so that the time required for the switch circuit 18 to reach a predetermined voltage for turning on does not become long.

As described above, according to this embodiment, the piezoelectric element 7
, An external switch is applied to the piezoelectric element 7 as an intermittent impact load, and the generated charges are accumulated in the capacitor 16 and then discharged collectively.
Since the light pulse is generated by causing the light emitting diode 9 to emit light, it is possible to reliably convert the detection signal into an optical pulse and send it to the optical fiber 11 even though it is small.

Although each of the above-described embodiments is an example of a push button switch, the present invention can be applied to a limit switch with a similar configuration.

[0019]

As described above, according to the first aspect of the present invention,
If only one optical fiber is used, wiring is cumbersome.
And the problem of cost increase can be solved. Also,
Eliminates the need for power sources such as batteries, making maintenance and handling easy and
A safe, small and inexpensive optical switch can be obtained
You. Furthermore, the pressurizer reciprocates multiple times each time external pressure is applied.
External force given by moving the piezoelectric element
Switch that efficiently converts power into power is selected and intermittent
Such a pulsed light signal also facilitates its detection.
According to the second aspect of the present invention, the piezoelectric element and the light emitting device
The output from the piezoelectric element is connected to the capacitor connected in parallel with the element.
By sequentially charging the raw charge, the generated charge is effective and
A large amount can be stored and sufficient after discharge.
It is possible to obtain sufficient light emission luminance. And claim 3
In the described invention, the voltage of the capacitor has reached a predetermined value
Sometimes the switch circuit is closed to make the light emitting element emit light.
With this, the light emitting element intermittently emits a high-intensity optical signal.
Send to fiber for reliable and efficient signal transmission
Become.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a part of an embodiment of the invention described in claim 1 ;

FIG. 2 is a diagram for explaining the operation of the embodiment of the invention described in claim 1 ;

FIG. 3 is a graph for explaining the operation of the embodiment of the invention described in claim 1 ;

FIG. 4 is a circuit diagram of an embodiment of the invention described in claims 2 and 3 ;

FIG. 5 is a graph for explaining the operation of the embodiment of the invention described in claims 2 and 3 ;

[Explanation of symbols]

 2 push button 4 leaf spring 5 pressurizer 6 pressure receiving plate 7 piezoelectric element 8 coil spring

Claims (3)

(57) [Claims] 1. Applied through a piezoelectric element and a leaf spring
A pressurizer that operates by external pressure and presses the piezoelectric element against the spring force of the coil spring, and a light emitting element that is connected to the piezoelectric element and emits an optical signal to the optical fiber by emitting light by the voltage generated by the piezoelectric element. When the magnitude of the external pressure applied to the leaf spring exceeds a certain value,
Activates the pressurizer by reversing the direction of the spring force of the spring
And pressurize the piezoelectric element.
An optical switch characterized in that an indenter is reciprocated a plurality of times between a leaf spring and a piezoelectric element side to press the piezoelectric element a plurality of times. 2. The optical switch according to claim 1, wherein a capacitor is connected in parallel to the piezoelectric element and the light emitting element. 3. The optical switch according to claim 2, wherein a switch circuit that closes when the charging voltage of the capacitor rises to a predetermined value is connected in series to the light emitting element.