JPH0672808B2 - Radiation thermometer - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiation thermometer for measuring the temperature of a measurement target by using infrared rays from the measurement target, and more particularly to an optical system thereof.

Conventional technology Conventionally, there are refraction type and reflection type in the optical system of the radiation thermometer for low temperature range using infrared rays of 10 μm band, but the cost is low,
Since there is no problem of dispersion, which is a problem in refractive optics,
Reflective optical systems are often used.

Among them, the Cassegrain type shown in FIG. 6 is generally used.
Since there is a convex mirror (4) in the light beam to the convex mirror (4), a part of the light beam traveling from the measurement object to the concave mirror (2) is blocked by the convex mirror (4), and it is difficult to obtain a bright optical system. In FIG. 6, (6) is a detector that receives infrared rays from the measurement object, (8) is a pinhole plate having a pinhole (8a) that limits the measurement area, and (10) is a detector (8).
The chopper is driven by a motor (M) so as to intermittently control the incidence of light on it, and (12) is a temperature sensitive element that measures the temperature of the detector (8) itself, which serves as a reference for measurement.

FIG. 7 shows another example of a conventional reflection type optical system. In this case, unlike the Cassegrain type optical system, there is no convex mirror for blocking the light flux from the measurement object, but a concave mirror (1
The chopper (16) placed in the light flux to 4) intercepts the light flux largely in place of the concave mirror, darkens the optical system, and drives the chopper (16) and the motor (18).
Has to be supported in the light flux, which has the disadvantage of being structurally complicated.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention The present invention has been made to improve the drawbacks of the conventional optical system as described above, and an object thereof is to use a chopper for controlling the incident light to the detector while having a structure. It is an object to provide a radiation thermometer that is simple and can obtain a bright optical system.

Means for Achieving the Object In order to achieve the above object, the present invention applies an AC voltage instead of a chopper and a motor for driving the chopper, which are conventionally used to control incident light on a detector. As a result, a bimorph type piezoelectric vibrating plate is used which generates bending vibration in the thickness direction. The bimorph diaphragm is composed of a shim electrode made of a thin metal plate having elasticity and a pair of external electrodes that support the shim electrode so as to sandwich it from both sides.
A shutter spring made by processing the shim electrode is provided at one end. Further, the bimorph diaphragm is arranged such that the length direction is perpendicular to the optical axis and the width direction is parallel to the optical axis, and the end opposite to the shutter spring is supported outside the measurement light beam of the optical system.

Therefore, according to the present invention, the bimorph diaphragm that constitutes the chopper only exposes its thickness to the light flux from the measurement target to the concave mirror, and only the detector blocks the light flux to the concave mirror. The optical system can be made significantly brighter and the configuration can be simplified.

Embodiment An embodiment of the present invention is shown in FIGS. here,
2 is a view seen from A in FIG. 1, and FIG. 3 is a view seen from B. In FIG. 1, reference numeral (20) is a concave mirror which reflects and focuses infrared rays from the object to be measured. Reference numeral (22) is a pinhole plate placed at the focusing position, and infrared rays that have passed through the pinhole (22a) that limits the measurement area are detected by the detector (24).

Both the detector (24) and the pinhole plate (22) are assembled in the detector holder (26), and the detector holder (26) is connected to the window (28
It is held by a support member (28) having a). (3
Reference numeral 0) is a temperature sensitive element for measuring the self temperature.

The chopper is composed of a bimorph diaphragm (34) having a shutter spring (32) fixed to one end thereof, and the shutter spring (3
2) is located close to the pinhole (22a). Here, the bimorph diaphragm (34) is arranged so that the width direction is located in the optical axis direction of the optical system and the length direction is located in a direction perpendicular to the optical axis. The other end of the bimorph diaphragm (34) has two fixing members (36) and (3
It is fixed to the outside of the measurement light flux by sandwiching it with two screws (40) between it and 8). Here, the displacement amount of the bimorph diaphragm (34) depends on the length of the diaphragm (34), and the length of the diaphragm (34) corresponding to the sufficient displacement amount for opening and closing the pinhole (22a) is also this. It is easily obtained and reasonable by the arrangement.

Further, the fixing member (36) is fixed to the supporting member (28) with two screws (42). Then, the AC signal supplied to the bimorph diaphragm (34) is applied to the electrode (34a) via the fixing members (36) (38) contacting the electrode (34a).
It is directly applied to the b) from the AC electrode (E).

Here, in order to keep the voltage applied to the bimorph diaphragm (34) low, it is desirable that the vibration required for the bimorph diaphragm (34) is small. Therefore, it is preferable that the shutter spring (32) vibrates symmetrically with respect to the center of the pinhole (22a), and it is necessary that the shutter spring (32) is arranged close to the pinhole (22a). Adjustment for that purpose can be performed by loosening the four screws (40) (42) and adjusting the relative position of the shutter spring (32) with respect to the pinhole (22a).

For the adjustment of such a chopper, it is configured as shown in FIGS. 4 and 5. FIG. 5 is a view of FIG. 4 viewed from C. In FIGS. 4 and 5, the shutter spring (32) is made of a metal thin plate having a spring property. As a result, the shim material of the bimorph diaphragm (34) can be directly processed on the thin metal plate. Also,
On top of the pinhole plate (22) is a plastic thin plate (44) made of polyethylene, Teflon, etc. with self-lubricating properties that has an opening (44a) larger than the pinhole (22a).
However, the openings (44a) are overlapped and fixed so that they are concentric with the pinhole (22a). Then, the position of the shutter spring (32) is adjusted so that the shutter spring (32) is lightly touched with the plastic plate (44).

This adjustment is performed by sandwiching the bimorph diaphragm (34) between the fixing members (36) and (38), and after completing the adjustment, screw (4
Fix it by tightening (0). With this structure, the distance between the shutter spring (32) and the pinhole (22a) is kept constant by the thickness of the plastic plate (44) interposed therebetween. Further, since the shutter spring (32) has a very weak spring property and the plastic plate (44) is self-lubricating, the pressure generated by the contact does not matter. The fixing member (36) is fixed to the support base (50) by screws (46) and (48), and adjustment of the shutter spring (32) in the XY directions perpendicular to the optical axis is performed by these two screws (46). )(Four
8).

Further, according to the present embodiment, the fixed end support portion having a mechanism for adjusting the shutter spring (32) to the pinhole (22a) in a fixed positional relationship, and the drive signal application portion for the bimorph diaphragm. Since they are located outside the optical system, they do not block the light flux, so a bright optical system can be obtained, and the relative position of the shutter spring (32) with respect to the pinhole (22a) is easy to adjust. Has an advantage.

EFFECTS OF THE INVENTION As described in detail above, according to the present invention, a detector arranged on the image plane of a reflective optical system composed of a concave mirror for detecting infrared rays that has passed through a transmission region that limits a measurement range, and a transmission region at one end. A shutter spring is formed close to the optical axis, the length direction of which is perpendicular to the optical axis, and the width direction of which is parallel to the optical axis. And a chopper composed of a bimorph diaphragm fixed by the above, and is configured to intermittently control the incident light to the detector by driving the shutter spring by applying an AC signal to the bimorph diaphragm. With this configuration, as a chopper, only the thickness of the bimorph diaphragm is exposed to the light flux traveling from the object to be measured toward the concave mirror, and the chopper interrupts the light flux. Since only the blur detector is used, it is possible to obtain a bright optical system which has a simpler structure than the conventional device and has a small number of obstructions to the measurement light beam.

[Brief description of drawings]

FIG. 1 is a sectional view showing an optical system of a radiation thermometer according to an embodiment of the present invention, FIG. 2 is a front view showing a state in which FIG. 1 is seen from A, and FIG. 3 is seen from B in FIG. FIG. 4 is a front view showing a state in which FIG. 4 is viewed from C, and FIGS. 6 and 7 are conventional radiation thermometers, respectively. It is sectional drawing which shows the optical system for use. (22a); transmission region, (24); detector, (32); shutter spring, (34); bimorph diaphragm.

Claims (1)

[Claims] 1. A reflection optical system including a concave mirror, a detection unit arranged on an image forming surface of the reflection optical system, for detecting infrared rays that have passed through a pass band that limits a measurement range, and one end of the detection unit. It has a shutter spring for blocking light, and is arranged so that its length direction is perpendicular to the optical axis and its width direction is parallel to the optical axis. A chopper composed of a fixed bimorph diaphragm, and by applying an AC signal to the bimorph diaphragm, drives the shutter spring so as to fully open / close the infrared pass band, and intermittently emits light to the detection means. The bimorph diaphragm includes a shim electrode made of a thin metal plate having elasticity and a pair of external electrodes supporting the shim electrode so as to sandwich the shim electrode from both sides. Jitter spring radiation thermometer, characterized in that, is formed by processing the shim electrodes by removing the external electrodes on both sides of the bimorph diaphragm.