JPH05833Y2 - - Google Patents

Description

[Detailed explanation of the idea] (b) Industrial application fields The present invention relates to an infrared detector.

(b) Conventional technology At present, there is no U.S. patent for infrared detectors.
As disclosed in No. 4,485,305, there is a device in which the chopper mechanism is made smaller by forming it with a piezoelectric body and a pair of opposing bodies.

8 to 10 show such an infrared detector, 1 is a sensor case consisting of a metal header 2 and a cap 4 having a circular opening 3, and 5 is a sensor case that is attached to the cap 4 so as to cover the opening 3. The fixed infrared transmitting filter 6 is a pyroelectric infrared detector disposed inside the sensor case 1 facing the window 3, and the detector is made of tantalum which generates an electric charge based on the amount of change in incident infrared rays. Consists of lithium oxide (LiTaO ₃ ) single crystal. Reference numeral 7 denotes a chopper mechanism that changes the infrared rays incident on the detection body, and the chopper mechanism includes a pair of piezoelectric vibrators 8, 9 and the vibrators 8, 9.
A pair of opposing bodies 10, 1 fixed to each end of
It starts from 1. Further, a plurality of slits 12, 12, . . . of the same shape and size are formed in the opposing bodies 10, 11, respectively, to allow infrared rays to pass therethrough.
Reference numeral 13 denotes a shield body that covers the infrared detecting body 6, and a small hole 14 is bored in the shield body at a position facing the opposing bodies 10 and 11.

Thus, the vibrating bodies 8 and 9 periodically vibrate in opposite directions (directions A or B in FIG. 9), and as a result, the relative positional relationship of the opposing bodies 10 and 11 changes periodically. A state in which the slits 12, 12, . Then, in the above-mentioned superimposed state, infrared rays from the temperature-measuring part are transmitted through the infrared transmission filter 5 of the sensor case 1, the slits 12, 12 of both opposing bodies 10, 11, and the small hole 1.
On the other hand, in the non-overlapping state, only the infrared rays from the opposing bodies 10 and 11 enter the infrared detecting body 6 through the small hole 14, so that the infrared detecting body 6 The amount of incident infrared rays changes periodically, and a signal corresponding to the temperature difference between the temperature of the temperature-measuring section and the temperature of the opposing bodies 10 and 11 is output.

Further, the field of view of such a device is determined by the small hole 14 of the shield body 13, as shown by diagonal lines in FIG. 10, and it is possible to detect only infrared rays emitted from the temperature-measuring portion located within this field of view.

(c) Problems to be solved by the invention However, in such a device, as shown by the solid line in FIG.
11 and reaches the infrared detector 6, resulting in a problem that accurate measurements cannot be made.

(d) Means to solve the problem This invention was made in view of the problem.
Its structural features include an infrared detector, a case that houses the infrared detector and has an opening at a position facing the surface of the infrared detector, and a case that is arranged between the infrared detector and the opening and is non-transparent. In the infrared detector, the infrared detector includes a pair of opposing bodies having a transparent part and a translucent part, and a vibrating body that vibrates to periodically change the opening/closing degree of the transparent part of the pair of opposing bodies, wherein the aperture width A of the aperture is , the opening width B of the transparent part and the distance C between the opening and the opposing body are (A+B)/2C<1
The reason is that

(e) Effects With such a configuration, the viewing range is defined by the opening formed in the case, and it is possible to prevent infrared rays incident from outside the viewing range from being diffracted by the opposing body and reaching the infrared detecting body.

(F) Embodiment FIG. 1 shows an embodiment of the present invention. The differences between this embodiment and the conventional example shown in FIG.
(See FIG. 9) and that the distance C between the opening 3 and the opposing body 11 is set to (A+B)/2C<1.

Note that in FIG. 1, the same parts as in FIG. 10 are denoted by the same numbers, and explanations thereof will be omitted.

FIGS. 2a and 2b show the sensitivity distribution characteristics in the direction parallel to the extending direction of the slit 12 and the sensitivity distribution characteristic in the direction perpendicular to the extending direction of the slit 12 in the infrared detector of this embodiment, respectively. Also, Figure 3a,
b is in the direction parallel to the extending direction of the slit 12 of a conventional device in which the opening width A, the light-transmitting part width B, and the distance C between the opening and the opposing body do not satisfy the condition of (A+B)/2C<1. The sensitivity distribution characteristics and the sensitivity distribution characteristics in a direction perpendicular to the above-mentioned extension direction are shown. Note that the viewing range (viewing angle) of the apparatus used for such measurements was set to 10° in half value angle.

As is clear from FIGS. 2 and 3, the conventional device detects infrared rays incident from outside the visual field by diffraction at the opposing bodies 10 and 11 as described above (the shaded area in FIG. 3). On the other hand, in the device of this embodiment, infrared rays incident from outside the visual field are not detected.

4 and 5 show a second embodiment of the invention. The difference from the first embodiment is that in the first embodiment, the height of the cap 4 is increased, and (A+B)/2C
<1, but in this embodiment, an aperture 21 is attached to the conventional device so as to cover at least the cap 4 of the sensor case 1. 2 and the second opening 2.
The width A' of the second opening 22, the width B of the transparent portion of the opposing bodies 10 and 11, and the distance C' between the second opening 22 and the opposing body 11 are (A'+B)/2C'<1. Note that in FIGS. 4 and 5, the same parts as in FIGS. 1 and 8 are denoted by the same numbers, and explanations thereof will be omitted. Further, the aperture 21 is fixed to the end of the header 2 by caulking.

6 and 7 show a third embodiment of the present invention, which differs from the second embodiment in the method of mounting the aperture 21. Specifically, in this embodiment, the second
In this embodiment, one end of the aperture 21 is extended to cover the bottom surface of the header 2, and one end of the aperture 21 is secured to one end of the header 2, and the other end of the aperture 21 is brought into contact with the top surface of the cap 4 to form a sensor case. 1 is fixed so as to be sandwiched between both ends of the aperture 21. Note that in FIGS. 6 and 7, the same parts as in FIGS. 4 and 5 are denoted by the same numbers, and explanations thereof will be omitted.

Also in the second and third embodiments (A′+
B) When the condition of /2C'<1 is satisfied, as in the first embodiment, the infrared rays incident from outside the visual field can be prevented from entering the infrared detector 6 by diffraction at the opposing bodies 10 and 11. .

(g) Effects of the invention The infrared detector of the invention can prevent infrared rays incident from outside the field of view from being diffracted by the opposing body and entering the infrared detecting body, making accurate measurement possible.

[Brief explanation of the drawing]

Fig. 1 is a front sectional view showing the first embodiment of the present invention, Fig. 2 is a characteristic diagram showing the sensitivity distribution characteristics of the device of the first embodiment of the invention, and Fig. 3 is the sensitivity distribution characteristic of the conventional device. 4 and 6 are side sectional views showing the second and third embodiments of the present invention,
Figures 5 and 7 are - of Figures 4 and 6, respectively.
8 and 10 are a side sectional view and a front sectional view showing a conventional example, and FIG. 9 is a top view showing a chopper mechanism. DESCRIPTION OF SYMBOLS 1...Case, 3...Aperture, 6...Infrared detector, 7...Chopper mechanism, 8, 9...Vibrating body, 1
0,11...Opposing body.

Claims (1)

[Scope of utility model registration request] an infrared detector; a case in which the infrared detector is housed and has an opening at a position facing the surface of the infrared detector; a case disposed between the infrared detector and the opening, a non-transparent part and a transparent part; an infrared detector comprising: a pair of opposing bodies having a vibrating body that vibrates to periodically change the opening/closing degree of the light-transmitting portion of the pair of opposing bodies; An infrared detector characterized in that an aperture width B and a distance C between the aperture and the opposing body are (A+B)/2C<1.