JPH029130Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to an optical actuator that has a simplified structure and improves light absorption efficiency.

[Prior art]

Recently, research has been carried out to irradiate light onto a substance that has the property of absorbing light energy and to examine the thermal changes in the substance that absorbed the light energy. Furthermore, for process control and the like, a light-pneumatic exchanger that converts light energy into output air pressure has been proposed.
Compared to so-called electro-pneumatic converters that convert electrical signals into air pressure proportional to the electrical signals, this has the advantage of not being susceptible to electrical noise and being superior in explosion-proof properties.One example of this is the structure shown in Figure 1. things are known. In other words, 1 is the fulcrum 2
The flats are swingably supported around the
3 and 4 are containers and nozzles disposed on both sides of one end of the flapper 1 in close opposition to each other; 5 is a bellows disposed on the other end of the flapper 1;
6 is a control relay. The end face of the container 3 facing the flapper 1 is open, and this opening is closed by an elastic membrane 7 that contacts the flapper 1. A photoresponsive substance 8 made of gas, liquid, or solid having a high coefficient of thermal expansion is sealed inside the container 3, and the optical signal is guided by an optical transmission member 9 such as an optical fiber. .

Reference numeral 10 denotes an input pipe for supplying a constant supply air pressure P ₀ , and this input pipe 10 is connected to the output side of the control relay 6, and a branch pipe 10a branched from this input pipe 10 has a throttle 11 in the middle. and is connected to the nozzle 4 and another branch pipe 1
0b is connected to the input side of the control relay 6. The control relay 6 is
It consists of a diaphragm 12 that is pressed by air pressure from the branch pipe 10b, and a relay valve 14 that closes the outlet 13 of the relay 6 by the operation of the diaphragm 12.

Reference numeral 15 denotes an output tube whose one end is connected to the bellows 5, and this output tube 15 is connected to the discharge port 13 of the control relay 6.

In such a configuration, when an optical signal is irradiated into the container 3 from the tip of the optical transmitter 9, the photoresponsive substance 8 absorbs the optical energy and expands, thereby stretching the elastic film 7. Then, the flapper 1 is rotated counterclockwise about the fulcrum 2 to narrow the distance between it and the nozzle 4, so the nozzle back pressure increases.
The diaphragm 12 of the control relay 6 is pressed and displaced to the right. Therefore, the relay valve 14 opens the discharge port 13, and the output air pressure P discharged from the output pipe 15 increases. This output air pressure P is supplied to a control valve (not shown), etc., and at the same time is guided to a feedback bellows 5 to apply a clockwise torque to the flapper 1. Therefore, the elastic membrane 7 that acts on the flapper 1 balance with the counterclockwise force of the flapper 1, and stop the movement of the flapper 1. As a result, an output air pressure proportional to the input optical signal is obtained.

By the way, in such a light-air pressure converter, the container 3 that encloses the photoresponsive substance 8 is formed into a cylindrical body, so when light is diffused within the container 3, the light directly or reflected on the inner surface of the container expands and contracts. When it hits the elastic membrane 7, it is absorbed (generally, it is not reflected because it is a soft elastic material), resulting in poor efficiency.

[Summary of the idea]

This was developed in view of the drawbacks of the conventional art, and its purpose is to provide an optical actuator that reduces absorption of light by a photoresponsive container and improves conversion efficiency.

〔Example〕

Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.

The second is a configuration diagram showing an embodiment in which the optical actuator according to the present invention is applied to an optical-pneumatic converter. In the figure, reference numeral 20 denotes a base formed in a substantially U-shape, and a flapper 22 is supported at the center of the base 20 so as to be tiltable in the left-right direction about a fulcrum 21.

Reference numeral 23 denotes a bellows as a photoresponsive container, and the inner surface of the bellows 23 is coated with aluminum or the like to form a reflective surface with high reflectance or a completely diffused reflective surface 24 coated with barium sulfide or powdered sulfur. , one end is fixed to one surface of the free end side of the flapper 22, and the other end is fixed to the base 20.
is fixed to the inner surface of one side. A photoresponsive gas 25 is sealed inside the bellows 23, and an optical signal 26 is transmitted to the optical fiber 25.
7. The photoresponsive gas 25 is chemically stable and has a large coefficient of expansion (α) and a large pressure coefficient (β).
It is desirable that the material be available at a low cost, and furthermore, be able to utilize light effectively and reduce loss. Therefore, in this example, carbon dioxide gas (CO2), which has a light absorption wavelength of 4 to 5 μm, is used. ₂ ) is used as the principal component. For this reason, infrared rays of 4 to 5 μm are used as the optical signal 26, for example, as shown in FIG.
The signal is pulse train modulated as shown in Figure 1, or pulse width modulated as shown in Figure b.

Furthermore, when comparing carbon dioxide gas and methane gas as photoactive substances, the chemical stability and body expansion coefficient (0.37×
10 ^-3 /℃), and it can be said that carbon dioxide gas is cheaper in terms of price. The coefficient of body expansion is large compared to other gases.

28 is a temperature compensation bellows, and this bellows 2
8 has the same shape and size as the bellows 23 and faces the bellows 23 with the flapper 22 in between, and contains the same gas 2 as the photoresponsive gas 25 inside.
9 is included.

At the tip of the flapper 22, a nozzle 30 is disposed on the surface facing the temperature compensating bellows 28 in close proximity to each other, and a constant pressure (for example, 1.4
Kg/cm ² ) of supply air P ₀ is supplied through the throttle 31. Reference numeral 32 denotes a control relay to which nozzle back pressure is transmitted, which has the same configuration as shown in FIG. It is configured to be guided to a feedback bellows 34 disposed on the side.

In such a configuration, the optical signal 26 guided by the optical fiber 27 connects the bellows 2.
When the carbon dioxide gas 25 in 3 is irradiated, the carbon dioxide gas 25
absorbs light energy and expands thermally, causing the bellows 23
Stretch. In this case, the inner surface of the bellows has a high reflectance, so light energy (including reflected energy)
This allows direct thermal expansion of carbon dioxide gas, which has better conversion efficiency than thermal expansion due to temperature rise of bellows. In addition, since the optical signal 26 uses infrared rays having the same wavelength as the absorption wavelength of the carbon dioxide gas 25, the absorption efficiency is high, and the optical signal 26 guided into the bellows 23 is multiple-reflected on the reflective surface 24. Therefore, the absorption of light by the bellows 23 is small, and the optical signal 26 can be efficiently absorbed by the carbon dioxide gas 25. Further, although the bellows 23 thermally expands depending on the ambient temperature, since the bellows 28 for temperature compensation is provided, this does not appear as a displacement of the flapper 22, and therefore there is no effect due to changes in the ambient temperature. .

When the bellows 23 expands due to the absorption of the optical signal 26 by the carbon dioxide gas 25, the balance with the temperature compensation bellows 28 is lost and the flapper 22 is tilted to the right, which increases the nozzle back pressure and causes the output from the pilot relay 32 to increase. Increase air pressure P. This output air pressure P is supplied to the pneumatic control valve 33 to operate the valve, and at the same time is led to the feedback bellows 34, causing the bellows 34 to expand. As a result, the flapper 22 stops at a position where the clockwise torque by the bellows 23 and the counterclockwise torque by the bellows 34 are balanced.

Although the above embodiment has been described with reference to the case where the entire inner surface of the bellows 23 is used as a reflective surface, the present invention is not limited to this, and only the portion most irradiated by the optical signal 26 may be used as a reflective surface.

Furthermore, the present invention is not limited to the above embodiments, and can be modified in various ways. For example, if the converter is placed in a constant temperature bath,
No bellows 28 for temperature compensation is required.

[Effect of idea]

As explained above, in the optical actuator according to the present invention, the light-responsive container is made of a bellows, and at least a part of the inner circumferential surface of the bellows is made a reflective surface, so that light hits the inner circumferential surface of the bellows and undergoes multiple reflections. , light absorption by the bellows can be reduced. Therefore, the light absorption efficiency of the photoresponsive gas is improved, and a highly efficient optical actuator can be provided. Further, it is more effective if the entire inner circumferential surface of the bellows is made of a reflective surface with high reflectance. In addition, it has a simple structure and is inexpensive, and has great practical effects.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an example of a conventional optical-pneumatic converter, Fig. 2 is a block diagram showing an embodiment of the optical actuator according to the present invention applied to the optical-pneumatic converter, and Fig. 3 is a block diagram showing an example of a conventional optical-pneumatic converter. Figures a and b are diagrams showing modulation of an optical signal. 22... flapper, 23... bellows (photoresponsive container), 24... reflective surface, 25... carbon dioxide gas (photoresponsive gas), 26... optical signal, 27... optical fiber, 28... temperature compensation bellows, 30... nozzle,
32...Pilot relay, 34...Feedback bellows.

Claims (1)

[Scope of utility model registration request] In the optical actuator, the optical actuator guides an optical signal into a photoresponsive container formed by enclosing a photoresponsive gas that absorbs light energy, and converts thermal expansion or thermal contraction change of the photoresponsive gas due to the light energy into displacement or force. An optical actuator characterized in that the response container is constructed of a bellows that can be expanded and contracted in the axial direction, and at least a portion of the inner circumferential surface of the response container is made into a reflective surface with high reflectance.