JPH0525032Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a heat ray sensor that can be used, for example, in a security device that detects heat rays emitted from a human body and issues an alarm, or in a device that automatically opens and closes a door using the heat rays.

In such a device, it is necessary to confirm the angular range in which hot rays are detected, that is, the field of view of the device, when manufacturing, installing, and maintaining the device. Therefore, conventionally, when performing this work, a light emitting element such as a small light bulb or a light emitting diode was placed at the position of the pyroelectric heat ray detection element to convert the heat rays focused by the lens into electrical signals and detect them. The area where the rays of light could be seen through the lens was detected. However, for this purpose, the heat ray detection element must be removed from the device and the light emitting element described above must be placed in its place.However, since the detection element is often built into a large printed wiring board, it is necessary to remove and attach only the element. Alternatively, it is extremely difficult to attach and detach the entire wiring board. Therefore, the present invention provides a heat ray sensor that can easily and accurately detect the field of view of the device without requiring such difficult attachment/detachment operations.

The present invention includes an appropriate heat ray focusing lens such as a synthetic resin Fresnel lens or a concave reflector, and an elliptical reflector whose one focus is the focal point of the lens, and the other focus of the elliptical reflector or this focus. A heat ray detection element is disposed at a position where the passing heat rays are further focused, that is, substantially at the above focal point position, and a light emitting element for visual field detection is detachably disposed at the focal point. Therefore, when detecting the field of view, etc., by moving a printed wiring board etc. that is difficult to attach or remove, there is no need for difficult work such as placing a light emitting element in that position, and an appropriate light emitting element, such as a small and lightweight light emitting element, can be used. By installing a diode or the like so that it can be moved between the focal point and the side outside the optical path, the field of view can be detected very easily and accurately. In addition, since the elliptical reflecting mirror can effectively expand the viewing angle of the heat ray detection element itself, the optical path length inside the device can be shortened and the heat ray detector can be made smaller. It has the function and effect of

The drawing shows an optical system showing an embodiment of the present invention, and the heat ray converging lens 1 may be constructed of a synthetic resin Fresnel lens or a concave reflecting mirror. A light emitting element 2 such as a diode is arranged. This element is mounted on a shaft 3 so that it can be rotated as shown by the chain line and moved out of the optical path. Further, an elliptical reflecting mirror 4 through which the heat rays are incident through the focal point P is provided, and this reflecting mirror is fixed so that one of the pair of focal points coincides with the focal point P. A suitable heat ray detection element 5, such as a pyroelectric type, is arranged so that the heat rays focused by the reflector 4 are incident on the other focal point Q of the reflector 4.
Although this device is formed so that the straight line PQ is perpendicular to the axis of the lens 1, this angle can be selected arbitrarily.

In the above device, when the light emitting element 2 is placed at the focal point P as shown by the solid line, the light ray of this element travels in the opposite direction along the same optical path as the incident light ray and is projected in front of the lens 1. Therefore, when the lens is observed from the projection range of the light beam, the lens appears to shine with the color of the light generated by the light emitting diode, but when the lens is outside the above range, the lens appears dark. That is, by this observation, the field of view of the heat ray sensor can be easily confirmed and the device settings can be made. Next, when the light emitting element 2 is moved to the position indicated by the chain line, the heat rays passing through the lens 1 are detected by the element 5, so when a person or the like enters the range, that is, the field of view, an output is sent from this element and an alarm is sent out. etc. are issued. In addition, since an elliptical reflecting mirror is used as the reflecting mirror 4, and the focal point of the lens 1 and the heat ray detection element 5 are arranged at both focal points, by arranging this at an appropriate angle with respect to the axis of the lens 1, the element 5 The convergence angle α of the heat rays incident on the lens 1 can be made smaller than the convergence angle β of the lens 1. Therefore, the convergence angle β of the lens 1 can be increased without being limited by the viewing angle of the heat ray detection element 5, and the device can be made smaller.

[Brief explanation of drawings]

The drawings are diagrams showing the configuration of an embodiment of the present invention.
In the figure, 1 is a heat ray focusing lens, 2 is a light emitting element, 3 is a rotation axis of element 2, 4 is an inertial reflector, and 5
is a heat ray detection element.

Claims (1)

[Scope of utility model registration request] A heat ray lens that focuses heat rays on one point, an elliptical reflector that has the above point as one focus, and a heat ray lens that is arranged at the other focus of the ellipse reflector so that the heat rays that are focused at the focal point are reflected by the ellipse reflector. A heat ray sensor comprising an incident heat ray detection element and a light emitting element which is detachably arranged at the focal point of the heat ray lens and projects visible light forward in the opposite direction to the heat rays through the lens.