JP2522509Y2 - Infrared detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an infrared detector using a pyroelectric infrared element.

[Conventional technology]

An infrared detector using a pyroelectric infrared element has a characteristic that charges are generated based on the amount of change in incident infrared light.
Therefore, it is necessary to periodically intermittently change the amount of incident infrared rays. Therefore, in the conventional infrared detector, the ninth
As shown in the figure, a motor mechanism 3 rotating at a low speed is provided in front of a pyroelectric infrared element 2 for receiving infrared light from an object 1 to be detected.
In addition, a disk 4 having windows at predetermined angles as shown in FIG. 10 is provided as a light shielding means on the front surface thereof. A mechanical chopper type that interrupts light is used. According to such a method, the motor itself has a large shape, and it is necessary to provide a speed reduction mechanism in the motor in order to rotate the disk 4 at a low speed to interrupt the infrared rays. Further, there is a disadvantage that the detector itself becomes large because a disk having a large diameter is required.

Therefore, as shown in FIG. 11, a pair of slit plates 5a and 5b, which are light shielding means having slits at predetermined intervals, are intermittently vibrated by bimorph vibrators 6a and 6b, and a pyroelectric infrared ray held on a base 7 is provided. There has been proposed an infrared detector in which infrared light applied to the element 8 is intermittent (see Japanese Patent Application Laid-Open No.
-129226).

[Problems to be solved by the invention]

However, in such an infrared detector using a conventional bimorph vibrator, it is necessary to apply a high voltage, for example, a voltage of several tens to several hundreds of volts, to drive the bimorph vibrators 6a and 6b. Therefore, there is a disadvantage that a booster is required in the drive circuit and the circuit becomes complicated. Also, since the displacement of the bimorph vibrator is as small as about 1 mm, for example,
A plurality of slit plates 5a and 5b are provided so that infrared rays enter when the slits overlap. Accordingly, the amount of light received by the pyroelectric infrared element 8 is always less than half the amount of incident light, and there is a disadvantage that the sensitivity of the infrared detector is reduced as compared with the mechanical chopper method shown in FIG.

The invention of claims 1 and 2 of the present application has been made in view of such a problem of the conventional infrared detector, and does not require a high pressure for the infrared detector and can be downsized without lowering the sensitivity. It is a technical task to do so. In addition, the invention of claim 1 of the present application has, in addition to this problem, a special technical problem that the heat from the light shielding means of the infrared element is not applied so that infrared rays can be detected accurately.

[Structure and Effect of the Invention] (Means for Solving the Problems) The invention of claim 1 of the present application is a device in which a magnet is mounted and is rotatably held, and is located at a position separated from a rotation axis of the rotor. A fixed pyroelectric infrared device, a flat plate-shaped wing plate whose one end is integrally attached to the rotating shaft of the rotor, and an infrared emissivity mounted on the surface of the wing plate facing the pyroelectric infrared device Low metal flakes, electromagnets arranged on both sides of the rotor magnet, and power supply means for supplying an alternating voltage to the electromagnet, the energizing direction of which changes at predetermined time intervals. The device is characterized in that the incident surface of the pyroelectric infrared element is opened and closed by rotating in a pendulum shape.

The invention of claim 2 of the present application is directed to a rotor having a magnet mounted thereon and rotatably held, a pyroelectric infrared element fixed at a position separated from a rotation axis of the rotor, and a flat plate-shaped one end. A wing plate integrally mounted on the rotating shaft of the rotor, a coil, and mounted toward the rotor from both ends of the coil,
An electromagnet including a pair of stators each having a notch at a position facing the rotor, and a power supply unit for supplying an alternating voltage whose energizing direction changes to a coil of the electromagnet every predetermined time,
And the rotor magnet is mounted such that the magnetic poles are located along a plane including the rotation axis and the center line of the blade, and the notch of the stator is provided with the center line of the rotation shaft and the blade. It is notched in a direction perpendicular to the plane including the opening, and the opening position of the pyroelectric infrared element by the blade is periodically rotated between the closing position and the closing position. It is assumed that.

(Operation) According to the invention of claim 1 of the present application having such characteristics, a rotor having a magnet and rotatably held is provided with a vane plate for opening and closing the incident surface of the pyroelectric infrared device. The polarity of the electromagnets provided on both sides of the rotor is periodically switched. In this case, since the blade plate makes a pendulum motion at a predetermined period, the incident surface of the pyroelectric infrared device is opened and closed at predetermined time intervals.

In addition, since a thin metal flake with low infrared emissivity is provided on the surface of the wing plate facing the infrared element, even when heat is transmitted when the wing plate is pendulum-moved, infrared rays generated from the wing plate are used for the pyroelectric infrared device. I can hardly tell.

In the invention of claim 2 of the present application, the magnet of the rotor is configured such that the magnetic poles are located along a plane including the rotation axis and the center line of the blade, and a notch is formed in the pair of stators. At the open position and the closed position of the pyroelectric infrared device by the blades, the magnetic poles are set to the stop positions corresponding to the protrusions of the stator. In this way, the pyroelectric element can be opened at the open position for a certain period of time.

(Effects of the Invention) Therefore, according to the invention of claims 1 and 2 of the present application, the electromagnet is driven by a low-voltage AC power supply without requiring a high voltage as compared with a conventional infrared detector using a bimorph vibrator. ,
By rotating the rotor, the front surface of the infrared detector can be opened and closed by the pendulum motion of the blade plate. Therefore, when the blade plate moves and the front surface of the infrared element is opened, the light receiving surface is completely opened, so that the sensitivity can be prevented from lowering. Further, as compared with the chopper method using a disk, a motor and a speed reduction mechanism are not required, and further, since a disk having a large diameter is not required, an effect that the size can be reduced can be obtained.

Further, in addition to this effect, the invention of claim 1 of the present application has the advantage that even when the temperature of the blade plate itself rises due to heat generated by energizing the electromagnet and friction between the rotating shaft and its holding portion, infrared rays are focused by the metal flakes on the front surface. Almost no transmission to the electronic infrared device. Therefore, the effect of eliminating the influence of the temperature change of the blade plate and accurately detecting the infrared ray of the object can be obtained.

According to the invention of claim 2 of the present application, in addition to the above-mentioned effects, the magnetic pole is stopped corresponding to the protrusion of the stator between the pyroelectric infrared device by the blade plate and the open position and the closed position of the device. Position. For this reason, an effect is obtained that the opening and closing of the infrared element can be reliably performed.

[Explanation of Example]

FIG. 1 is an assembly configuration diagram of an infrared detector according to an embodiment of the invention of claims 1 and 2, FIG. 2 is an elevation view, FIG. 3 is a front view, and FIG. 4 is a side view. is there. In the infrared detector according to the present invention, a cylindrical rotor 11 including permanent magnets magnetized to be magnetic poles S and N on both sides is fixed on a rotating shaft 12, and is used for a bearing provided on an upper portion of a fixed base 13. It is rotatably held by a rotor bearing 14 formed in a U shape with a groove. The fixed base 13 has a shallow circular concave part on the rotor 11 side, a bearing groove is provided at the center thereof, and a notch is provided on the side. Further, a circular through hole 13a is provided below it at a position separated from the rotation axis. And this rotor 1
A pair of stators 15 and 16 formed in a U-shape from both sides of 1 are attached from the side of the fixed base 13. Stator 15, 16 is rotor 1
The top and bottom of the portion facing 1 are cut out in a C shape, and the center is cut out in a U shape. A core 17 is connected between the stators 15 and 16 and a coil 18 serving as an electromagnet is wound therebetween. One end of a substantially oval blade plate 19 is attached to the rotation shaft 12 of the rotor 11. As shown in FIGS. 1 and 3, a pyroelectric infrared element 20 is fixed to a through hole 13a provided below the rotating shaft 12 below the fixing base 13. As shown in FIGS. 5 (a) and 5 (b), the magnet of the rotor 11 has magnetic poles on the surface along the rotation axis and the center line of the blade plate 19, and the stators 15, 16 It is configured to have a notch in a vertical direction.

FIGS. 5 (a) and 5 (b) are schematic views of the pyroelectric infrared detector constructed as described above, and an AC power supply 21 serving as a power supply means is connected to the coil 18. FIG. When a square wave as shown in FIG. 6 (a) is applied from the AC power supply 21 to the coil 18, for example, the polarity of the stators 15 and 16 is changed at predetermined intervals as shown in FIGS. 5 (a) and 5 (b). To change. Therefore, the rotor 11 rotates accordingly, and the blade plate 19 performs a pendulum motion. Here, the voltage applied to the coil 18 may be, for example, a sinusoidal AC voltage as shown in FIG. 6B, or a pulse waveform having a different direction at regular intervals as shown in FIG. 6C. You may make it. And this voltage is, for example, 5V to 12V, so that the period of the pendulum motion,
For example, it is assumed that a signal having a frequency of 2 to 10 Hz is applied.
In this way, the wing plate 19 pendulums at regular intervals, and the incident surface of the pyroelectric infrared element 20 is shielded and opened. Accordingly, the infrared light from the detected object is intermittent, and the charge of the pyroelectric element is discharged, so that the amount of change in the infrared can be detected.

In this embodiment, the rotor is rotated by changing the polarity of the stator at predetermined time intervals. However, as shown in FIG. Stop plates 22 and 23 are provided to prevent
May be rotated.

FIG. 8 (a) is a diagram showing a main part of an infrared detector according to a second embodiment of the present invention of claim 1, and FIG. 8 (b) is a side view thereof. In the present embodiment, in addition to the first embodiment, a metal flake 30 is provided on the back surface of the blade 19 facing the pyroelectric infrared device 20. The metal flake 30 is, for example, a circular flake corresponding to the shape of the pyroelectric infrared device 20 as shown in the figure, and a metal flake having a low infrared emissivity, such as an aluminum foil, is used. Other configurations are the same as those of the first embodiment. When the infrared detector is operated in this manner, the infrared rays to the pyroelectric infrared element 20 are intermittently connected with the rotation of the blade 19 as shown in FIG. 8 (b). At this time, heat generated by energization of the coil 18 or friction between the fixed base 13 and the rotating shaft 12 is transmitted to the blade plate 19, and the temperature of the blade plate 19 rises slightly. However, even with such a rise in temperature, the blades 19
Infrared rays from are blocked by the metal flake 30 and do not reach the pyroelectric infrared element. Therefore, the amount of change in infrared rays can be accurately detected by the pendulum movement of the slats 19.

[Brief description of the drawings]

FIG. 1 is an assembly configuration diagram of an infrared detector according to a first embodiment of the present invention, FIG. 2 is an elevation view thereof, FIG. 3 is a front view thereof, FIG. 4 is a side view thereof, and FIG. FIGS. 5 (b) and 5 (b) are diagrams showing the rotating state of the rotor when voltages are applied to the coil of the infrared detector of the present embodiment in different directions, respectively. FIG. 6 is a diagram showing various voltages applied to the coil. FIG. 7 shows waveforms, FIG. 7 is a front view of another embodiment in which the rotation of the rotor is restricted,
FIG. 8 (a) is a diagram showing a main part of an infrared detector according to a second embodiment of the present invention, FIG. 8 (b) is a diagram showing a positional relationship between a thin metal piece provided on a blade and an infrared element, FIG. 9 is a schematic view showing a conventional chopper type infrared detector, FIG. 10 is a view showing a slit disk thereof, and FIG. 11 is a perspective view showing a conventional infrared detector using a bimorph vibrator. 11 ... rotor, 12 ... rotating shaft, 13 ... fixed base, 14 ... rotor bearing, 15, 16 ... stator, 18 ... coil, 19 ...
Blades, 20 ... pyroelectric infrared device, 21 ... AC power supply, 2
2,23 ... stop plate, 30 ... metal flake

Claims (2)

(57) [Scope of request for utility model registration] 1. A rotor having a magnet mounted thereon and rotatably held, a pyroelectric infrared device fixed at a position separated from a rotation axis of the rotor, and a flat plate-shaped one end of the rotor. A vane plate integrally attached to a rotating shaft; a thin metal sheet having a low infrared emissivity attached to a surface of the vane plate facing the pyroelectric infrared element; and a metal plate disposed on both sides of the magnet of the rotor. An electromagnet; and a power supply means for supplying an alternating voltage to the electromagnet, the energizing direction of which changes at predetermined time intervals. An infrared detector configured to open and close a surface. 2. A rotator to which a magnet is attached and which is rotatably held; a pyroelectric infrared element fixed at a position separated from a rotation axis of the rotator; An electromagnet including a blade plate integrally mounted on the rotating shaft, a coil, and a pair of stators mounted toward the rotor from both ends of the coil and each having a notch at a position facing the rotor. Power supply means for supplying an alternating voltage whose energizing direction changes to the coil of the electromagnet at predetermined time intervals, wherein the magnet of the rotor extends along a plane including a rotation axis and a center line of the blade plate. The notch of the stator is cut out in a direction perpendicular to a plane including a rotation axis and a center line of the blade plate, and the stator is provided with a notch. The open position of the electronic infrared device Infrared detector, characterized by being configured the vane so as to cyclically pivot between a position.