JPH08201874A - Light blocking device - Google Patents

Abstract

(57) [Summary] [Objective] To provide a light blocking device that is small in size, has a small temperature rise, and can stop incident light in a blocked state. A light blocking device comprising: a light detecting section for detecting the incident light H; a light blocking means for blocking the incident light H; and a drive section for driving the light blocking means, in a traveling direction of the incident light H. On the other hand, a rotary shaft 51 extending in the vertical direction, a transmission hole 6 as a light blocking means provided on the rotary shaft 51, and a rotary motor 5 for driving the rotary shaft 51 are provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light blocking device that blocks a light beam at an arbitrary time cycle.

[0002]

2. Description of the Related Art Conventionally, an apparatus for blocking a light beam at an arbitrary time cycle is shown in FIG. 7, for example. In the figure, L is a light source that generates incident light H, S is a shutter that blocks the incident light H, SL is a slit provided in the shutter S, and M is
Is a piezoelectric bimorph that opens and closes the shutter S, and K is a photodetector that detects incident light H. When the voltage is not applied to the piezoelectric bimorph M, the shutter S is in the open state, and the incident light H generated from the light source L is the shutter S.
After passing through the slit SL, the photodetector K detects the incident light H. When a voltage is applied to the piezoelectric bimorph M, the piezoelectric bimorph M is displaced and the shutter S is closed to block the incident light H. The applied voltage is repeatedly turned on / off to periodically block the incident light H (for example, refer to S:
ANYO TECHNICAL REVIEW VO
L. 21 No. 2 JUN. 1989). Also, FIG.
As shown in, a shutter S'where a plurality of fan-shaped blades are arranged in a disk shape is rotated by a rotation motor M ', and the incident light H incident on the slit SL provided in the photodetector K is interrupted intermittently. There are things (for example, the actual development Sho 60-1144
74).

[0003]

However, in the former prior art, since the piezoelectric bimorph is used for driving the shutter, only a small amount of incident light can be blocked. That is, when the length of the piezoelectric bimorph is 9 mm, only a displacement amount of about 2.4 μm can be obtained with respect to the applied voltage V, the shutter displacement amount is small, and the detection light amount is small, so that the detection error is large. was there. Therefore, in order to increase the amount of displacement of the shutter, a method of increasing the length of the piezoelectric bimorph or operating the piezoelectric bimorph at the resonance frequency can be considered. However, if the length of the piezoelectric bimorph is increased, the structure of the light blocking device becomes large, and if it is operated at the resonance frequency, there is a problem that the incident light cannot be stopped in a blocked state. Further, in the latter conventional example, since a disk-shaped shutter having a diameter that is at least twice the length of the slit is required, the overall size of the light blocking device becomes large and the drive motor becomes large. There is a problem in that the temperature of the photodetector is increased. SUMMARY OF THE INVENTION It is an object of the present invention to provide a light blocking device that is small in size, has a small temperature rise, and can stop incident light in a blocked state.

[0004]

In order to solve the above problems, the present invention provides a photodetector for detecting incident light, a light interceptor for intercepting the incident light, and a driver for driving the light interceptor. In the light blocking device including the light blocking means, the light blocking means is provided on a rotary shaft extending in a direction perpendicular to the traveling direction of the incident light, and a drive unit for driving the light blocking means drives the rotary shaft. It consists of a rotary motor. Further, the light blocking means comprises a transmission hole having a diameter substantially the same as the size of the light detection portion and penetrating perpendicularly to the axial direction of the rotating shaft. The light blocking means is fixed to the outer circumference of the rotating shaft having a diameter substantially the same as the distance between the two light detecting units, and extends in the axial direction of the rotating shaft and in the radial direction. And a light blocking plate in the shape of a flat plate having a size that covers the photodetector. Furthermore, the light shielding plate is surrounded with a gap,
And an air guide made of a translucent material having an exhaust port provided in a portion facing the photodetection section and an air inlet port communicating with the periphery of the rotary motor provided around the rotation shaft. Is.

[0005]

With the above-mentioned means, the light-blocking means consisting of the light-transmitting hole or the light-blocking plate having substantially the same size as the light-detecting portion is provided on the rotary shaft, and the rotary shaft is rotated to intermittently block the incident light. Since the shutter operation for the incident light is performed, it is possible to obtain an arbitrary amount of light and to provide an extremely small light blocking device. Further, since an air guide surrounding the light blocking plate is provided so that the cooling air generated by the fan action of the light blocking plate is applied to the light detecting unit and the rotary motor, the temperature rise of the light detecting unit and the rotary motor is suppressed to a low level. be able to

[0006]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1A is a perspective view showing a first embodiment of the present invention, a part of which is cut away. In the figure, 1 is a flat base, 2 is a photodetector provided on the base 1, 3 is a light source that emits incident light H toward the photodetector 2, and 4 is on the base 1 that covers the photodetector 2. In the box-shaped case provided in the above, an incident window 41 that transmits the incident light H from the light source 3 is provided above the case 4. Reference numeral 5 denotes a rotary motor fixed inside the case 4, reference numeral 51 denotes a rotary shaft of the rotary motor 5, and the diameter of the rotary shaft 51 is larger than the size (width and length) of the photodetector 2, The axis 51 is arranged so as to intersect perpendicularly with the incident light H. Reference numeral 6 denotes a transmission hole penetrating at a position intersecting with the incident light H of the rotating shaft 51 in a direction perpendicular to the axial direction of the rotating shaft 51, and has a size substantially the same as the size of the light detecting section 2 and a light blocking means. To form. When the rotary shaft 5 is rotated by the rotary motor 5 in a state where the incident light H is emitted from the light source 3 toward the photodetector 4, as shown in FIG. 2, every time the rotary shaft 51 rotates 90 degrees, ( The state in which the incident light H passes through the transmission hole 6 and is detected by the photodetector 2 as shown in a) and the state in which the incident light H is blocked by the rotating shaft 51 as shown in FIG. Repeat.
In this way, a transmission hole having substantially the same size as that of the light detection unit is provided on the rotating shaft, and by rotating the rotating shaft, incident light passing through the transmitting hole is intermittently blocked to perform a shutter operation of the incident light. Therefore, the light blocking device can be formed in an extremely small size. Also, by controlling the rotation angle of the rotary motor, the amount of incident light can be changed arbitrarily. To stop the incident light in the cutoff state, stop the rotating shaft in the state shown in Fig. 2 (b). Good.

FIG. 3 is a perspective view showing a second embodiment of the present invention, which has almost the same structure as that of the first embodiment, except that a rotary shaft is used instead of the transmission hole 6 provided as the light blocking means. 51 '
Has a diameter substantially equal to the distance between the two light detecting portions 2, and is a flat light blocking plate 6 that is slightly larger than the size of the light detecting portions 2 extending along the axial direction of the rotating shaft 51 ′ and extending in the radial direction. 'Is provided on the outer circumference of the rotary shaft 51'. Light source 3
In a state in which the incident light H is emitted from the
When the rotary shaft 51 ′ is rotated by the rotary motor 5, as shown in FIG. 4, every time the rotary shaft 51 ′ rotates by 90 degrees, the incident light H causes the rotary shaft 51 ′ to block the light as shown in (a). The state of passing the both sides of the plate 6'and being detected by the photodetector 2 and the state of blocking the incident light H by the light blocking plate 6'as shown in (b) are repeated. in this way,
Since the shutter operation of the incident light is performed by rotating the light blocking plate having substantially the same size as the light detecting portion provided on the rotation shaft, the light blocking device can be formed in an extremely small size.

FIG. 5 is a side sectional view showing a third embodiment of the present invention, and FIG. 6 is a front sectional view thereof. In the configuration of the second embodiment, an air guide 7 is provided around the light blocking plate 6'and the rotary motor 5. The air guide 7 is made of quartz glass, Pyrex glass, light-transmissive plastic or the like that transmits the incident light from the light source, and the light-shielding plate 6 '.
It is provided with a gap around it so as to surround the. An exhaust port 71 is provided in a portion of the air guide 7 that faces the light detection unit 2, and an intake port 72 that communicates with the periphery of the rotary motor 5 is provided around the rotary shaft 51 ′. When the rotating shaft 51 ′ is rotated, a fan action is generated in the light blocking plate 6 ′, and ambient air is sent as cooling air in the outer peripheral direction and is discharged from the exhaust port 71 toward the light detection unit 2. The discharged cooling air removes heat from the light detecting portion 2, passes between the air guide 7 and the case 4, passes through the side surface of the rotary motor 5, enters the air inlet 72, and returns to the light blocking plate 6 ′. Circulate. During this circulation, the heat generated by the rotary motor 5 is also absorbed by the cooling air, the heat absorbed by the cooling air is transmitted to the case 4, and is further radiated from the case 4 to the outside air. In this way, the cooling air generated by the rotation of the light blocking plate cools the photodetector and the rotary motor, so that the temperature rise of the photodetector can be suppressed to a small level and the error due to the temperature can be reduced. .

[0009]

As described above, according to the present invention, the light-blocking means including the light-transmitting hole or the light-blocking plate having substantially the same size as the light-detecting portion is provided on the rotary shaft, and the rotary shaft is rotated. Since the incident light is intermittently interrupted to perform the shutter operation of the incident light, there is an effect that an extremely small light interrupting device capable of obtaining an arbitrary light amount can be provided. Further, since an air guide surrounding the light blocking plate is provided so that the cooling air generated by the fan action of the light blocking plate is applied to the light detecting unit and the rotary motor, the temperature rise of the light detecting unit and the rotary motor is suppressed to a low level. There is an effect that can be.

[Brief description of drawings]

FIG. 1 is a perspective view showing a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a state of operation of the first embodiment of the present invention.

FIG. 3 is a perspective view showing a second embodiment of the present invention.

FIG. 4 is an explanatory diagram showing the operation of the second exemplary embodiment of the present invention.

FIG. 5 is a side sectional view showing a third embodiment of the present invention.

FIG. 6 is a front sectional view showing a third embodiment of the present invention.

FIG. 7 is a perspective view showing a conventional example.

FIG. 8 is a perspective view showing a conventional example.

[Explanation of symbols]

1 base, 2 light detectors, 3 light sources, 4 cases, 41
Entrance window, 5 rotation type motor, 51, 51 'rotation axis,
6 transmission holes, 6'light blocking plate, 7 air guide, 71 exhaust port, 72 intake port

Claims (4)

[Claims] 1. A light blocking device comprising a light detection unit for detecting incident light, a light blocking unit for blocking the incident light, and a drive unit for driving the light blocking unit, wherein the light blocking unit comprises: The light blocking device, characterized in that the driving unit provided on a rotary shaft extending in a direction perpendicular to the traveling direction of the incident light and driving the light blocking means is a rotary motor driving the rotary shaft. 2. The light blocking unit according to claim 1, wherein the light blocking unit comprises a transmission hole having a diameter substantially the same as the size of the light detection unit and penetrating perpendicularly to the axial direction of the rotating shaft. apparatus. 3. The light blocking means is fixed to an outer circumference of the rotary shaft having a diameter substantially the same as a distance between the two light detecting portions, and is arranged along the axial direction of the rotary shaft and has a diameter. The light blocking device according to claim 1, comprising a flat light blocking plate having a size that extends in a direction and covers the light detection unit. 4. An exhaust port, which surrounds the light blocking plate with a gap, and which is provided in a portion facing the photodetector, and communicates with the rotary motor provided around the rotary shaft. The light blocking device according to claim 3, further comprising an air guide made of a translucent material having an air inlet.