JPH049558Y2 - - Google Patents

Description

[Detailed Description of the Invention] "Field of Industrial Application" The present invention relates to the structure of a dual-type passive infrared detection device used for intrusion alarms and the like.

``Prior Art'' FIG. 2 is a plan view of essential parts of a conventional dual-type passive infrared detection device, and FIG. 3 is a view showing the field of view of a concave mirror.

1 is a dual-type infrared detector, 2 is a composite concave mirror, and multiple concave mirrors A, B, C, D,
It is composed of E.

Concave mirrors A to E have respective concave mirror fields of view SA,
They are arranged so that the infrared rays from SB, SC, SD, and SE are reflected and focused on the detection elements a and b of the infrared detector 1.

The outputs of the sensing elements a and b are differentially combined with each other, and are output when there is a difference in the incidence of infrared rays on the sensing elements a and b.

The concave mirror visual fields SA to SE shown in FIG. 3 each consist of a pair of visual fields starting from the sensing elements a and b, and this visual field is the sensitive zone.

4 is an infrared detection device including an infrared detector 1 and a compound concave mirror 2. When an infrared source such as a human crosses the concave mirror field of view SA to SE, the infrared detection device 4 detects and outputs infrared rays to detect an object such as a human. .

The infrared rays reflected by the concave mirrors A to E enter the detection elements a and b through a window 3 provided in the infrared detector 1. Therefore, the range of infrared rays that can be incident on both the detection elements a and b is limited by the line connecting the edge of the window 3 and the detection elements a and b.

The effective detection angle of the infrared detector 1 is the angle range formed by the straight line Aa from the sensing element a to the left end of the concave mirror A and the straight line Eb from the sensing element b to the right end of the concave mirror E in FIG.

In order to increase the size of the concave mirror within the above-mentioned limited angle, the infrared detector 1 may be moved away from the concave mirrors A to E, that is, L in FIG. 2 may be increased, but this has the disadvantage that the entire device becomes large.

"Problem that the invention attempts to solve" The entire device, especially the distance L between the concave mirror and the infrared detector 1
This is intended to increase the infrared detection ability by increasing the size of the concave mirrors A to E without increasing the size of the infrared rays.

"Means for Solving the Problems" In order to solve these problems, the present invention divides a concave mirror in a specific direction (for example, concave mirror C) into two parts and places them on the outside of the effective detection angle. By configuring the sensing zone, the concave mirror can be made larger without increasing the size of the device, thereby increasing the infrared detection ability.

The drawings will be explained in detail below.

"Embodiment" FIG. 1 is a plan view of the main part showing an embodiment of the present invention.

1 is the aforementioned dual-type infrared detector having two detection elements a and b. 2' is a composite concave mirror, which is composed of concave mirrors C1, A', B', D', E', and C2. A'a, E'b, I, m are straight lines connecting the detection elements a, b and the edge of the window 3 of the infrared detector 1, and between the straight lines A'a, E'b, the detection elements a, b This is the range where infrared rays can commonly be incident, and is the effective detection angle described above. Concave mirror C1 between straight lines A'a and I
The range between the straight line E'b and m is a range in which infrared rays can be incident only on the sensing element b on the opposite side from the concave mirror C2, and has not been used in the past.

Here, the concave mirrors C1 and C2 are adjusted so that they both have a pair of identical fields of view, for example the field of view in Figure 3.
Almost the same as SC. Also, concave mirrors A', B', D', and E' are the fields of view SA, SB, SD, and SE of concave mirrors A, B, D, and E.
have the same perspective.

The angle formed by the straight line A'a and the straight line E'b is the effective detection angle for the infrared detector 1. In contrast to the five concave mirrors arranged in FIG. The concave mirror of is getting larger. Although the concave mirrors C1 and C2 are arranged outside the above-mentioned effective detection angle, by focusing each on the detection element on the opposite side, a pair of identical fields of view can be created and used effectively.

The distance L between the concave mirror and the infrared detector 1 is the same as in the case of FIG. 2, and the concave mirror can be made larger without increasing the size of the device.

"Operation" Even if the compound concave mirror 2 included in the infrared detecting device 4 in FIG. 3 is replaced with the compound concave mirror 2' in FIG. 1, a similar field of view is produced.

That is, if an infrared source such as a human body enters the concave mirror field of view SA to SE, the amount of infrared rays on detection elements a and b will change, and infrared detector 1 will generate an output according to the difference to detect the presence or movement of a human body. Can be detected.

"Effect of the invention" As explained above, according to the invention, by dividing the concave mirror in a specific direction into two and placing them at both ends of the compound concave mirror, the concave mirror can be made larger without increasing the size of the device, increasing infrared detection capability. can do. As a result, it is possible to make the infrared detection device highly sensitive.

[Brief explanation of the drawing]

FIG. 1 is a plan view of essential parts showing an embodiment of the present invention, FIG. 2 is a conventional dual-type passive infrared detection device, and FIG. 3 is a view showing the field of view of a concave mirror. 1...Infrared detector, 2,2'...Compound concave mirror,
A, B, C, D, E, A', B', D', E', C1,
C2...Concave mirror, 3...Window, 4...Infrared detection device, SA, SB, SC, SD, SE...Concave mirror field of view,
Aa, Eb, A'a, E'b, I, m...straight line.

Claims (1)

[Scope of utility model registration request] In an apparatus in which a plurality of concave mirrors with different viewing directions are provided and infrared rays in a direction corresponding to each concave mirror are detected by a dual-type infrared detector placed at a substantially common focal position of each concave mirror, two concave mirrors corresponding to a specific direction are detected. A passive infrared detection device characterized in that the concave mirrors are divided and each concave mirror is placed outside the effective detection angle of the infrared detector, and both constitute a pair of sensitive areas.