JPH0228467Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a detection range adjustment mechanism in a moving object detector.

In a thermal type moving object detector, radiant energy such as far infrared rays emitted by moving objects etc.
Detection is performed by an array of mirrors (preferably parabolic mirrors) each with its reflection optical axis facing one heat-sensitive detection element. That is, each mirror has a detection pattern that radiates out, and the detection range of a moving object is restricted by the total angular range of these patterns. Therefore, a known and common method for adjusting such a detection range is to narrow the detection angle range by successively shielding the mirrors at the ends of the mirror array, and conversely by removing these shields. It is something that expands.

However, in this method, when the detection angle range is narrowed, a portion of the mirror originally included within the effective directivity angle of the detection element is erased, resulting in poor usage efficiency of the detection element and a loss in optical gain.

In order to overcome the above-mentioned drawbacks of the detection range adjustment mechanism, the present invention uses a movable mirror that can be moved in and out from outside the mirror array so as to cover the front of the mirror part located in a part of the mirror array. and the movable mirror covers the front face of the mirror portion, so that the incident axis of the radiant energy set by the movable mirror in place of the mirror portion occupies an angular position inside the incident axis of the mirror portion. be.

Therefore, the mechanism of the present invention not only eliminates the incident axis of the mirror portion forming the outermost detection pattern (which usually corresponds to the limit of the effective directivity angle of the detection element), but also blocks it. A new incident axis located inside this incident axis is set using a movable mirror, the detection density is increased, and the usage efficiency of the detection element is maintained.

Embodiments of the present invention will be described below with reference to the drawings.

In the figure, 1 is a fixed mirror consisting of partial mirrors 1a, 1b, 1c, 1d and 1e arranged substantially in an arc shape, and 2a and 2b are movable mirrors. 3 and 4 are stop plates for the movable mirrors 2a and 2b, and 5 is a radiant energy detector consisting of a pyroelectric element or other heat-sensitive element.

Mirror portions 1a, 1b, 1c of fixed mirror 1,
The front faces facing the detectors 5 of 1d and 1e are paraboloids, and, for example, detection patterns A to E projected on a line 6 shown at the bottom of the figure along the moving direction of the object to be monitored, respectively. The incident radiant energy is reflected toward the detection surface of the detection element 5. The reflected radiation is detected by the detection element 5
The light is focused on the detection surface of the light, and its strength can be effectively detected.

The movable mirrors 2a and 2b are also parabolic mirrors, and in the open position shown by the solid line in the figure,
They are supported by stop plates 3 and 4, respectively, to open the outer end mirror portions 1a and 1e of the fixed mirror, which are themselves blocked from the detection element 5 by the stop plates 3 and 4.

Now, when the movable mirrors 2a and 2b are driven so as to occupy the positions shown by the imaginary lines, these mirrors 2a and 2b move toward the mirror portions 1 at both ends of the fixed mirror 1.
a, 1e are covered and hidden from the detector 5, and the radiant energy is incident from the projection patterns F and G formed between the projection patterns B and C and between C and D, respectively. The angle is maintained at such an angle that it has a reflection axis for making the light incident on the sensing surface of the sensing element 5 in a focused manner.

Therefore, the monitoring range when movable mirrors 2a and 2b are open is a wide range 7 covering detection patterns A to E, and the monitoring range when movable mirrors 2a and 2b are blocked is B, C, and D.
The range is narrowed to 8. Since the detection patterns F and G are added to this range 8, it is possible to substantially reduce the non-detection space and have a dense detection range, thereby lowering the electrical gain. Therefore, it has advantages such as a high signal-to-noise ratio.

As described above, the present invention provides a preferred detection range adjustment mechanism for crime prevention and other moving object detectors.

[Brief explanation of drawings]

The figure is a diagram showing an embodiment of the present invention. 1... Fixed mirror, 2a, 2b... Movable mirror, 3, 4... Stop plate, 5... Detection element.

Claims (1)

[Scope of utility model registration request] By arranging a plurality of parabolic mirror parts in a substantially circular arc shape, energy radiation that enters each mirror part at different angles from a position sufficiently distant compared to the radius of curvature of this mirror arrangement can be In a moving object detector in which the radiant energy is reflected and focused on approximately one point, and a radiant energy detection element is aligned with the focused point, the mirror array is arranged so as to cover the front surface of at least one mirror portion of the mirror array. A movable parabolic mirror that can be freely entered and exited from the outside is provided, and the movable parabolic mirror covers the front surface of at least one mirror portion, so that the incident axis of the radiation set in place of the mirror portion can be set at that mirror portion. A detection range adjustment mechanism for a detector, characterized in that the angle is located inside the incident axis of a mirror portion.