JPS6132335Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a light detection device using a pyroelectric polymer film.

Piezoelectric polymer materials such as polyvinylidene fluoride are known to have pyroelectric properties. By utilizing the pyroelectricity of such a polymer material and using it as a photoelectric conversion element, a photodetecting device can be constructed. That is, the pyroelectric polymer film can be used to configure detection devices such as fire alarms and intrusion detectors, as well as detection elements of optical calorimeters for measuring the output of laser light.
A photoelectric conversion element made of such a polymer material is
For example, it can be obtained by polarizing a polar material such as polyvinylidene fluoride under DC voltage. A photoelectric conversion element made of a polymer film is stretched and attached to a frame to constitute a photodetector. When light enters such a device, the photoelectric conversion element outputs an electrical output corresponding to the incident light.
A light measurement or light sensing operation will be performed. However, the structure in which the photoelectric conversion element is stretched around a frame alone is susceptible to the influence of electrical noise from a commercial AC power source and other external sources, resulting in malfunctions. Furthermore, when measuring the intensity of laser light using such a device, it is affected by electrical noise from the laser oscillator and the amplifier, making it impossible to make accurate measurements.

The present invention was developed in view of these problems, and consists of a light-receiving element made of a pyroelectric polymer film with electrodes on both sides, and a structure in which the light-receiving element is stretched around its periphery. a conductive frame for holding the light-receiving element, and a back plate that faces the surface of the light-receiving element opposite to the incident side with a predetermined gap and is attached to the frame;
The back plate is formed of a conductive material or a conductive layer is formed on the back plate, and the electrode on the incident side of the light receiving element, the frame, and the back plate or the conductive layer thereof. The present invention relates to a photodetecting device characterized in that a shielding case is formed by electrically connecting the above and the above to each other to form a shield case. Therefore, the device will not malfunction due to external electrical noise, and no errors will occur in the measured values.

The present invention will be described below with reference to the drawings, with reference to the illustrated embodiments. In this embodiment, the present invention is applied to an optical calorimeter for laser light. This calorimeter, as shown in Figures 1 and 2,
Pyroelectric polymer film 1 constituting a photoelectric conversion element
A pair of rings 2 and 3 clamp the peripheral edge of the film 1 from the front and back to hold it in a stretched state, and a transparent protection plate 4 is attached to the front side of the ring 2 to protect the polymer film 1. and a back plate 5 attached to the back side of the ring 3.

The pyroelectric polymer film 1 used in this example is, for example, a polymer containing a highly polar monomer such as vinyl fluoride, vinylidene fluoride, tolufluoroethylene, or fluorochlorovinylidene, or a copolymer. It may be a polarized polymer or a composition mainly composed of these polymers or copolymers. Among these, monopolymers or copolymers containing 40 mol % or more of vinylidene fluoride are particularly preferred because they have extremely high pyroelectricity. Furthermore, polymer films consisting of compositions containing vinylidene fluoride polymers or copolymers as a main component, mixed with PZT or other inorganic ferroelectric materials can also be used because they have high pyroelectric properties. becomes.

When such a pyroelectric polymer film 1 is used as a photoelectric conversion element of a detection device, electrodes 6 and 7 are attached to both sides of the film. The electrode 6 on the light incident side may be an infrared absorbing electrode made by coating the surface of a metal conductor electrode with a highly light absorbing film such as gold black or carbon paint, or an infrared absorbing electrode made of a metal conductor electrode coated with a film of good light absorption such as gold black or carbon paint, or a material such as tin oxide, indium oxide, etc. A transparent electrode made of a transparent conductor or an extremely thin film of gold, nickel, etc. that can transmit light is used. Furthermore, the electrode 6 on the incident side is formed over the entire surface of the polymer film 1. In other words, it should extend to its periphery. This electrode 6 is electrically connected to a conductive ring 2, which will be described later, and constitutes a part of the shield case.

The electrode 7 formed on the surface of the polymer film 1 opposite to the incident side may be an extremely thin film of nickel, aluminum, or the like. Further, this electrode 7 is not formed on the entire surface of the film 1, but a predetermined gap is formed between it and the ring 3. Therefore, this electrode 7 is not electrically connected to the ring 3, but instead is connected to the input terminal of the voltmeter 11 via the lead wire 8, the connector 9, and the shield wire 10.

The pair of rings 2 and 3 have a size of, for example, 100 mm, and are made of conductive metal. Steps 12 and 13 are formed on the opposing surfaces of these rings 2 and 3, respectively, and the peripheral edge of the polymer film 1 is clamped at these steps 12 and 13. ing. Instead of the step, the ring may have a slight inclination that becomes thinner toward the inside, or there may be no step or inclination. In this way, the film 1 is held stretched by the frame 14 formed by the rings 2 and 3. A transparent protection plate 4 attached to the front surface of the frame 14 allows laser light to pass through, protects the film 1, and prevents noise caused by air vibration. , sapphire, polyvinylidene fluoride, or the like. Note that this protection plate 4 is not necessarily necessary and may be omitted.

The back plate 5 attached to the back side of the frame body 14 is made of conductive metal, contacts the back side of the ring 3, and is connected to the ring 3 by screws.
Therefore, the back plate 5 is electrically connected to the electrode 6 on the incident side of the polymer film 1 via the rings 2 and 3. Furthermore, a small hole 15 is formed in the back plate 5, and the lead wire 8 is inserted through this small hole 15.
is penetrated. A connector 9 is attached to the outer surface of the back plate 5 around the small hole 15, and its negative terminal is directly electrically connected to the back plate 5. Therefore, this negative terminal constitutes a ground line. The back plate 5 faces the back surface of the film 1 with a predetermined distance therebetween. Note that this back plate 5 may be formed integrally with the ring 3.

In such a configuration, when a laser beam is incident on the polymer film 1 from the outside through the transparent protection plate 4, the pair of electrodes 6, 7 of the film 1 is caused by the pyroelectricity of the polymer film 1. A voltage corresponding to the intensity of the laser beam is generated between the two. Since electrode 6 is held at ground potential, this output voltage is taken out by electrode 7 and supplied to voltmeter 11 via lead wire 8, connector 9 and shielded wire 10, where the output voltage is Measurements are taken.

Moreover, according to the calorimeter of this embodiment, the electrode 6 on the incident side of the polymer film 1, the frame body 14 consisting of a pair of rings 2 and 3, and the back plate 5 are electrically connected to each other, and A shield case is formed. Therefore, even if electrical noise is generated from, for example, an external commercial AC power source, a laser oscillator, an amplifier, etc., this noise is blocked by the shield case and will not enter the inside of the calorimeter. Therefore, highly reliable and accurate measurements are possible without affecting the measured values due to these electrical noises. In addition, since this shield case is composed of the electrode 6 of the polymer film 1, the frame 14, and the back plate 5, there is no need to provide a separate case, making the meter with a shield function compact. Can be provided.

Although the present invention has been described above with reference to embodiments, the present invention is not limited to the above-mentioned embodiments, and various modifications can be made based on the technical idea of the present invention.

For example, the above embodiment relates to a laser beam calorimeter, but the present invention is applicable to a fire alarm,
It is also possible to apply it to a light detection device such as an intrusion detector.

Further, in the above embodiments, the back plate is made of a conductive metal, but a non-conductive back plate may be used and a conductive layer may be formed on the surface thereof.

As is clear from the above, according to the present invention, since the detection device using a pyroelectric polymer film is provided with a shield case, the device does not malfunction and the measured values do not change. It becomes possible to provide a highly reliable detection device without causing errors. Moreover, since the shield case consists of the electrode on the incident side of the pyroelectric polymer film, the frame that stretches this film, and the back plate, even if the shield case is installed, the The sensor does not become large, making it a compact detection device.

[Brief explanation of the drawing]

FIG. 1 is an exploded perspective view of a laser beam calorimeter according to an embodiment of the present invention, and FIG. 2 is a longitudinal sectional view of the same meter. In addition, in the symbols used in the drawings, 1...polymer film, 2, 3... ring, 5
. . . back plate, 6, 7 . . . electrodes, 14 . . . frame body.

Claims (1)

[Scope of utility model registration request] A light-receiving element made of a pyroelectric polymer film and provided with electrodes on both sides; a conductive frame for holding the light-receiving element by stretching it around its periphery; and a surface on the incident side of the light-receiving element. and a back plate that faces the opposite side with a predetermined gap and is attached to the frame, and the back plate is formed of a conductive material or the back plate is made of a conductive material. A conductive layer is formed, and the electrode on the incident side surface of the light receiving element, the frame, and the back plate or its conductive layer are electrically connected to each other to form a shield case. A light detection device characterized by: