JPH0633385Y2 - Pyroelectric heat source detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a pyroelectric heat source detector used for human body detection for lighting control, fire alarm, and the like.

[Prior Art] Conventionally, there has been proposed a pyroelectric heat source detector in which a pyroelectric infrared detector in which a plurality of pyroelectric elements are arranged in parallel is arranged at the center of a dome-shaped Fresnel lens having a compound eye configuration. .

First, the pyroelectric infrared detector 1 is shown in FIGS. 4 (a) and 4 (b).
As shown in, for example, four pyroelectric elements are provided in the package 10.
1a, 1b, 1c, 1d are arranged in parallel, adjacent elements are connected in opposite polarities, and the combined output is output from the terminal 11. That is, the outputs of the pyroelectric elements 1a and 1d are positive and the outputs of the pyroelectric elements 1b and 1c are negative. The size of each element 1a-1d is 1.
It has a square shape of 1 mm x 1.1 mm, and the element spacing is 1.5 mm. Therefore, the center interval of each element is (1.1 / 2) +1.5
(1.1 / 2) = 2.6 mm.

Next, the dome-shaped Fresnel lens 2 is shown in FIG.
As shown in (b), it is divided into 12 to form a compound eye structure, and is supported by the lens frame 20. The optical axes of the four central lenses 2a are θ ₁ = 15 °, and the optical axes of the eight peripheral lenses 2b are inclined at an angle of θ ₂ = 32 ° with respect to the visual field center.
The viewing angle θ ₃ is set to 115 to 120 °.

The pyroelectric infrared detector 1 is arranged in the central portion C of the Fresnel lens 2 to form a pyroelectric heat source detector. When this heat source detector is arranged on the ceiling surface, a horizontal plane 2 m directly below it A detection area as shown in FIG. 6 is obtained. In the figure, the blackened portions indicate the locations where the detection beams exist, and 48 detection beams are arranged in a circle with a diameter of 3000 mm. To illustrate the length of one side of the detection beam, b ₁ = 156m
m, b ₂ = 178 mm. Further, exemplifying the intervals of the detection beams, c ₁ = 209 mm, c ₂ = 213 mm, c ₃ = 242 mm, c ₄ = 243 mm,
c ₅ = 358 mm. The length from the center of the detection area to the farthest detection beam is a ₁ = 1454 mm.

[Problems to be Solved by the Invention] FIGS. 7 (a) and 7 (b) show a case where two pyroelectric heat source detectors S are arranged on the ceiling surface for human body detection in a conference room. It is the top view and front view which show arrangement | positioning of a detection beam. A standard room in an office such as a building has a rectangular shape with a width W = 3200 mm and a depth L = 6400 mm, and the shape of each room is determined by this unit. The standard height H ₁ from the floor to the ceiling is 2700 mm, and the standard height H ₂ from the floor to the desk top is 700 mm. As is clear from FIG. 7 (a), a dead zone is generated at the corner portion of the detection area by each pyroelectric heat source detector. In order to eliminate this dead zone, it is necessary to arrange more pyroelectric heat source detectors.

The present invention has been made in view of such a point, and an object thereof is to provide a pyroelectric heat source detector that can be efficiently arranged so as not to generate a dead zone.

[Means for Solving the Problems] In the present invention, in order to solve the above problems, a pyroelectric infrared detector having a plurality of pyroelectric elements arranged in parallel is provided with a plurality of lenses. In a pyroelectric heat source detector arranged in the center of a dome-shaped Fresnel lens having a compound eye, the detection area is divided into approximately equal grids so as to form a square detection area on the object surface. The optical axes of a plurality of lenses are arranged on a line connecting each lattice point and the detector.

Further, a pyroelectric element is arranged on each vertex of a square on the element surface whose sides are parallel to the square-shaped detection area, and the center distance of each pyroelectric element is the lattice point of the object surface. By setting the distance to about half of the distance projected on the element surface by the projection magnification of the lens, the detection beams in the detection area are arranged substantially in a grid pattern at equal intervals.

[Operation] According to the present invention, since the detection area is square, the dead zone is unlikely to occur when it is installed on the ceiling surface of a rectangular conference room, etc. It can be performed. Further, since the detection beams are arranged in a grid pattern at equal intervals, uniform detection sensitivity can be obtained in the detection area.

[Embodiment] The configuration of an embodiment of the present invention will be described below. 2 (a) and 2 (b) are a front view and a sectional view of the Fresnel lens 2 used in the present invention. Domed Fresnel lens 2
Is composed of 16 divided lenses, and the periphery thereof is supported by the lens frame 20. Lens divided into 16 parts, lens 2a is 4
1 lens, 8 lenses 2b, and 4 lenses 2c. The center position of each lens determines the shape of the detection area and the arrangement of the detection beam. The configuration of the pyroelectric infrared detector 1 is the same as that of the conventional example shown in FIGS. 4 (a) and 4 (b), and is arranged in the central portion C of the dome-shaped Fresnel lens 2. The central axis z of the field of view of the Fresnel lens 2 is located at the center of the element surface of the pyroelectric infrared detector 1 and is perpendicular to the element surface. Angles θa, θb, formed between the center axis z of the visual field and the optical axes of the lenses 2a, 2b, 2c,
θc is 15.5 °, 32.5 °, and 40.6 °, respectively. The lenses 2a and 2c are arranged such that the centers of the lenses are arranged at intervals of 90 ° around the field center axis z. This state is shown in FIG. Also, the lens 2b is paired with two lenses each,
The centers of the respective lenses are arranged at intervals of 45 ° around the visual field center axis z. Then, this lens pair is moved around the central axis z of the visual field.
Eight lenses 2b are arranged by arranging them at intervals of 90 °. This is shown in FIG. 3 (b). With the lens having the above structure, as shown in FIG. 1, a square detection area is obtained, and the respective detection beams are substantially lattice-shaped and have equal intervals. By using the central portion C of the dome-shaped Fresnel lens 2 as a light receiving surface, the incident light from the object surface is efficiently condensed, but the distance r from the dome surface to the central portion C is the distance of each lens. It becomes the focal length, which is an important factor in determining the size of the detection beam. In this embodiment, taking the shape of the pyroelectric element into consideration, the distance from the dome surface to the center is r = 14.5 mm so that the size of the detection beam 2 m directly below the heat source detector is 200 mm or less on one side. And The lens area is determined so that the incident power from the target in each detection beam becomes equal on the object surface immediately below the heat source detector. That is, assuming that the angle formed by the visual field center axis z and the optical axis of the lens is θ, when the target is larger than the detection beam, A / cos ^{2 with} respect to a predetermined reference area A.
The area may be determined so as to be θ, or A / cos ³ θ when the target is smaller than the detection beam. Strictly speaking, it is necessary to consider the optical loss due to the keratera peculiar to the Fresnel lens.

When the above heat source detector is arranged on the ceiling surface, a detection area as shown in FIG. 1 can be obtained on a horizontal plane 2 m directly below it. Here, the horizontal surface 2 m directly below the heat source detector is assumed to be the tabletop of the conference room in consideration of the ceiling height. This detection area has a square shape with one side of 3000 mm. As a result, even in a rectangular conference room of 3200 mm × 6400 mm as shown in FIG. 7A, the dead zone does not occur if two heat source detectors are attached. Further, even in a larger conference room, the pyroelectric heat source detector can be efficiently arranged without providing a dead zone. In the figure, the blackened portions show the locations where the detection beam exists. In this embodiment, since the four pyroelectric elements 1a to 1d shown in FIG. 4 are projected on the object surface by the Fresnel lens 2 divided into 16, a total of 64 detection beams are arranged. The length from the center of the detection area to the farthest detection beam is a ₂ = 1513 mm. As an example of the length of one side of the detection beam, b ₃ = 156 mm, b ₄ = 179 mm, b ₅
= 199 mm. Further, exemplifying the intervals of the detection beams, d ₁ = 271 mm, d ₂ = 213 mm, d ₃ = 186 mm, d ₄ = 244 mm, d ₅
= 256 mm, d ₆ = 258 mm, d ₇ = 182 mm. In other words, the distance between the detection beams is approximately 200 mm, and since adjacent detection beams generate detection outputs of different polarities with respect to the heat source, it is possible to detect even a slight movement of the human body very efficiently. .

Since the length of one side (= 1.1 mm) of the pyroelectric element shown in FIG. 4 is projected about 160 times as the length b ₄ of one side of the average detection beam, the center interval of each element (= 2.6mm) is calculated to be about 410mm on the object surface. This interval pyroelectric infrared detector 1 is projected onto the object plane _{(d 2/2 + b 3} + d 5 + b 4
+ A d _4/2 ≒ 820mm) about half. With this configuration, the detection beams in the detection area are arranged in a grid pattern at equal intervals.

[Effect of the Invention] The present invention is a pyroelectric heat source detector in which a pyroelectric infrared detector having a plurality of pyroelectric elements arranged side by side is arranged in the center of a dome-shaped Fresnel lens having a compound eye. Since it has a striped detection area, it has an effect that the dead zone is unlikely to occur when it is installed on the ceiling surface of a rectangular conference room or the like, and the heat source can be detected with a minimum number.

If the detection beams are arranged in a grid pattern at equal intervals, there is an advantage that uniform detection sensitivity can be obtained in the detection area.

[Brief description of drawings]

FIG. 1 is a plan view showing a detection area of a heat source detector of the present invention, FIGS. 2 (a) and 2 (b) are front views and sectional views of a Fresnel lens used in the present invention, and FIGS. FIG. 4B is an explanatory view showing the arrangement of lenses in the above, FIG.
(B) is a front view and a sectional view of an infrared detector used in the present invention, FIGS. 5 (a) and (b) are a front view and a sectional view of a Fresnel lens used in a conventional example, and FIG. 6 is a heat source of the conventional example. FIGS. 7A and 7B are a plan view showing a detection area of the detector, and FIGS. 7A and 7B are a plan view and a front view showing an example of installation in the conference room. Reference numeral 1 is an infrared detector, 1a, 1b, 1c and 1d are pyroelectric elements, 2 is a Fresnel lens, and 2a, 2b and 2c are lenses.

Claims (2)

[Scope of utility model registration request] 1. A pyroelectric heat source in which a pyroelectric infrared detector having a plurality of pyroelectric elements arranged in parallel is arranged at the center of a dome-shaped Fresnel lens having a compound eye structure in which a plurality of lenses are arranged in parallel. In the detector, each optical axis of a plurality of lenses is arranged on a line connecting each of the lattice points obtained by substantially equally dividing the detection area into a lattice shape and the detector so as to form a square detection area on the object surface. A pyroelectric heat source detector characterized in that 2. Pyroelectric elements are respectively arranged on respective vertices of a square on an element surface whose sides are parallel to the square-shaped detection area, and the center intervals of the respective pyroelectric elements are the same as those on the object surface. 2. The pyroelectric heat source detector according to claim 1, wherein the distance between the lattice points is set to about half of the distance projected on the element surface by the projection magnification of the lens.