JPH1172386A - Human-body detecting sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a human-body detecting sensor by which the movement of a human body can be detected quickly by providing a logical sum circuit which outputs a detection signal on the basis of the logical sum of a plurality of judgment signals. SOLUTION: A logical sum circuit 5c computes a logical sum. When a first judgment part 5a outputs a first judgment signal or a second judgment part 5b outputs a second judgment signal, a judgment part 5 judges that a human body is detected, and it outputs a detection signal. The detection signal which is output from the judgment part 5 is held by a delay circuit 6 for a specific time. An output circuit 7 outputs an output signal to an external load 8 during a period in which the detection signal is input from the delay circuit 6. Thereby, even if the human body intrudes slowly into a detection area, the second judgment part 5b detects the very small movement of infrared rays generated due to the transverse shake of the human body or due to the fine movement of a foot, and it outputs the second judgment signal. As a result, the movement of the human body can be detected more quickly than in conventional cases.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an infrared type human body detection sensor that detects infrared rays emitted from a human body by an infrared detection element and controls an external load such as lighting based on the detection signal.

[0002]

2. Description of the Related Art Conventionally, a method of detecting a human body by an amount of change in infrared light includes a method of projecting infrared light and detecting a change amount of reflected light, and a method of directly detecting a change amount of infrared light emitted by a human body. There is. Among them, the method of detecting the amount of change in the infrared ray emitted by the human body does not require a light projector, and the setting of the detection area can be easily changed by changing the condition of the optical system of the light collector 1. In addition to the detection device for the lighting, it is also widely used for on / off control of the external load 8 such as lighting.

In a human body detecting sensor for directly detecting the amount of change in infrared rays generated by a human body, an infrared detecting element 2
Pyroelectric elements are often used. Then, the output of the pyroelectric element due to the infrared light condensed by the condenser 1 is amplified by the amplifying unit 3, and the waveform of the unnecessary frequency component is removed by the bandpass filter 4. When the output is larger than a preset threshold value, the output circuit 7 outputs a detection signal (see FIG. 5).

As shown in FIG. 6, this human body detection sensor is mounted on the ceiling of a long corridor or the like to detect the movement of a person who is far away from the mounting position of the human body detection sensor (about 15 m away). Think.

[0005] The detection area of the human body detection sensor is divided into a plurality of areas by lenses and mirrors of the human body detection sensor. (Hereinafter, this divided detection area is referred to as a detection beam.) The operation direction of the human body to be detected by the human body detection sensor is substantially perpendicular to the detection beam emitted from the human body detection sensor (FIG. 7). (See FIG. 8) and a direction toward the detection beam emitted from the human body detection sensor (see FIG. 8).

In the conventional human body detection sensor, the size of the detection beam and the frequency characteristics of the amplifier 3 are set so that the signal when the human body moves within the detection beam at the speed of normal movement increases. Therefore, when the human body moves in such a direction that a plurality of detection beams can move in a relatively short time as shown in FIG. 7, the human body can be immediately detected.

On the other hand, when the human body moves in a direction toward the detection beam from a place far away from the human body detection sensor, the human moves within one detection beam for a relatively long time. The infrared power incident on the infrared detecting element 2 of the human body detecting sensor gradually changes (see FIG. 9).

Normally, an infrared detecting element 2 accompanying a rise in temperature or the like
The change in the infrared power input to the device becomes gradual. For this reason, in the conventional human body detection sensor of this type, the amplifying unit 3 does not amplify the slowly changing infrared power in order to distinguish a change in infrared power due to a rise in temperature or the like from a change in infrared power due to invasion of the human body. Or removed by the bandpass filter 4. That is, as compared with the case where a plurality of detection beams are moved in a relatively short time, the input to the comparison circuit 9 when the human body moves in a direction toward the detection beam from a place far from the human body detection sensor. Becomes small. Therefore, if you are moving slowly within the same detection beam,
Since it does not easily exceed the preset threshold value, it takes more time to judge that the human body has entered than when moving multiple detection beams in a relatively short time, and the detection beam The invading human body cannot be detected immediately.

[0009]

In order to solve this problem, by increasing the focal length of the optical system and reducing the size of each detection beam, the incident infrared power accompanying the invasion of the human body is reduced as much as possible. There is a way to change over time. However, when the focal length is increased, the size of the optical system increases, and as a result, there is a problem that the size of the entire human body detection sensor increases.

By changing the characteristics of the amplifying unit 3 and the bandpass filter 4 of the human body detecting sensor, it is possible to increase the signal when moving slowly in the detection beam, as described above. Since it is not possible to distinguish between a case in which the floor or walls in the detection beam have changed in temperature due to sunlight or the like and a case in which a human body has entered the detection beam, the frequency of erroneous signal output increases. There is a problem that it will.

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above problems, and has as its object to quickly detect the movement of a human body when the human body moves slowly within one detection beam. It is an object of the present invention to provide a human body detection sensor capable of performing the following.

[0012]

According to the first aspect of the present invention,
A detection unit that outputs a voltage value corresponding to the amount of change in infrared light, and a first unit that has a first threshold and outputs a first determination signal when the output of the detection unit exceeds the first threshold. And a second threshold which is lower than the first threshold, and outputs a second determination signal when the output of the detector exceeds the second threshold a predetermined number of times within a predetermined period. And a logical sum circuit that outputs a detection signal based on a logical sum of the first determination signal and the second determination signal.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail with reference to FIGS. FIG. 1 is a schematic configuration diagram of the detection sensor. FIG. 2 is a diagram showing a detection beam arrangement of the detection sensor, and FIG.
(B) shows a view from above. FIG. 3 is an output waveform when the detection beam is crossed. FIG. 4 shows an output waveform when a human body moves from a distance to immediately below the detection sensor.

The human body detection sensor comprises a condenser 1, an infrared detecting element 2, an amplifying section 3, a bandpass filter 4, a first judging section 5a, a second judging section 5b, and an OR circuit 5c. And a delay circuit 6 and an output circuit 7. The external load 8 is turned on / off by a signal output from a human body detection sensor.

The light collector 1 is a multi-segment lens for condensing infrared rays generated from the human body. For example, a multi-segment Fresnel lens or the like capable of reducing the thickness of the lens to reduce the attenuation of incident light is used. .

The infrared detecting element 2 is constituted by a pyroelectric element or the like for converting a change in the collected infrared light into an electric signal.

The amplifying unit 3 amplifies the output of the infrared detecting element of about several hundred μV output in response to the change of the infrared ray, and outputs an amplified signal. Here, in consideration of the human body detection in particular, the amplification factor in the band is set to be high so that the output of the infrared detecting element 2 accompanying the moving speed of the human body is most amplified.

The bandpass filter 4 outputs a signal in a band which is considered to be generated due to a normal movement of the human body among the amplified signals, and removes the amplified signals in other bands.

The judging section 5 performs a detection judgment of a human body, and outputs a detection signal when judging that a human body is detected. The first judging section 5a, the second judging section 5b, and a logical sum circuit 5c.

The first judging unit 5a includes a first judging unit
And outputs the first determination signal when the amplified signal exceeds the first threshold.

The second judging section 5b compares the amplified signal with a second threshold set lower than the first threshold and determines the number of times that the amplified signal exceeds the second threshold (hereinafter referred to as pulse count). Value) and outputs a second determination signal when a pulse count value equal to or more than a predetermined number is obtained within a predetermined time. If the pulse count value is appropriately set (usually two or more times), the second determination signal will not be output erroneously when there is a temperature change caused by the incidence of sunlight or the like.

The first judging section 5a and the second judging section 5b are connected in parallel, and the output of each
c. The logical sum circuit 5c calculates a logical sum, and determines whether the first determination unit 5a outputs a first determination signal,
Alternatively, when the second determination unit 5b outputs a second determination signal, the determination unit 5 determines that a human body has been detected,
It outputs a detection signal.

The delay circuit 6 holds the detection signal output from the determination unit 5 for a predetermined time. During the period from when the detection signal is output by the determination unit 5 until a predetermined time elapses, the delay circuit 6 holds the detection signal. The detection signal is continuously output even when the detection signal is not output from the determination unit 5. In addition,
The time for holding the detection signal may be arbitrarily set. As a result, despite the existence of the human body,
When it is determined that the human body is not detected by the determination unit 5 due to various factors, it is possible to prevent the output of the detection signal from being stopped immediately.

The output circuit 7 outputs an output signal to the external load 8 while the detection signal is input from the delay circuit 6. The output signal to the external load 8 may be stopped while the detection signal is being input from the delay circuit 6. Further, a timer may be provided so that the time during which the output signal is continuously output to the external load 8 can be arbitrarily set.

The external load 8 is a lighting or the like installed on the ceiling, and is turned on when an output signal from the output circuit 7 is received, and turned off when the output signal is stopped. In addition,
The light may be turned on when an output signal from the output circuit 7 is received, and may be turned off after a predetermined drive time has elapsed.

Next, the operation of the human body detection sensor will be described. The infrared detection type human body detection sensor of the present embodiment, that is, the human body detection sensor of the type that directly detects the amount of change in infrared rays emitted by the human body, has a temperature difference between the background in the detection beam and the human body passing through the detection beam. Is detected as a change in the infrared power incident on the optical system.

Assume that this human body detection sensor is installed on the ceiling of a long corridor to detect a human body (see FIG. 2). The human body detection sensor used here uses a four-element type element in which the infrared detection element 2 includes four pyroelectric elements. 4
The element type element arranges four pyroelectric elements at four corners and connects adjacent elements with opposite polarities,
When infrared rays are simultaneously incident on the four pyroelectric elements, they cancel each other out and cancel the output. This prevents the generation of an erroneous signal due to a temperature change on the floor or the like. Also, the number of detection beams is 92
It is a beam (23 divided lenses x 4 elements).

The height at which the human body detection sensor is mounted is 2.5 m from the floor, and the detection range in the longitudinal direction of the corridor is 30 m. That is, the detection beam is provided 15 m before and after the human body detection sensor. Further, a plurality of detection beams are provided in a corridor of 30 m × 2 m.

Consider a case where a human body having a size of 170 cm in height, 40 cm in width and 20 cm in depth enters the space in which the human body detection sensor is installed at a low speed of about 0.5 m per second. FIGS. 3 and 4 show the amplified signal output from the bandpass filter 4 of the human body detection sensor at that time. In each figure, the solid line represents the first threshold value, the dashed line represents the second threshold value, and the second threshold value is about one third of the first threshold value.

FIG. 3 shows an amplified signal when the detection beam crosses a detection beam at a distance of 15 m from the human body detection sensor. The first signal is detected at a detection point a (a point at which the amplified signal exceeds a first threshold value) shown in FIG. The first determination signal is output assuming that the human body has been detected by the determination unit 5a. In this case, the human body is detected almost simultaneously when the human body enters the detection beam of the human body detection sensor.

Next, FIG. 4 shows an amplified signal when the vehicle enters the direction of the human body detection sensor from a point 15 m away from the human body detection sensor. In the conventional human body detection sensor, the conventional detection point exceeding the first threshold value is used. At c, the first judgment signal is output. However, in the human body detection sensor according to the present embodiment, when the pulse count value is set to three times, the second determination signal is output at the detection point b.
That is, if the pulse count value is set to an appropriate value, the presence of a human body can be detected more quickly than in the conventional method, even if the detection beam enters the detection beam slowly from a distance toward the human body detection sensor.

[0032]

As described above, according to the first aspect of the present invention, there is provided a detecting section for outputting a voltage value corresponding to the amount of change in infrared rays, and a first threshold value. A first determination unit that outputs a first determination signal when the first threshold value is exceeded, and a second threshold value that is lower than the first threshold value, and the output of the detection unit sets the second threshold value to a predetermined value. A second determination unit that outputs a second determination signal when a predetermined number of times is exceeded during a period, and a logical sum circuit that outputs a detection signal based on a logical sum of the first determination signal and the second determination signal Even if a human body slowly enters the detection area so as to head toward the detection beam from a distant place, the second determination unit may detect minute infrared rays generated due to the lateral movement of the human body or fine movement of the foot. Detects movement and outputs the second judgment signal, thus detecting the movement of the human body faster than before. It is advantageously possible to provide a human body detecting sensor becomes possible.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a detection sensor.

FIG. 2 is a diagram showing a detection beam arrangement of a detection sensor, and FIG.
Represents a view from the side, and (b) represents a view from the top.

FIG. 3 is an output waveform when a detection beam is crossed.

FIG. 4 is an output waveform when a human body moves from a distant position directly below a detection sensor.

FIG. 5 is a schematic configuration diagram of a conventional human body detection sensor.

FIG. 6 is a diagram illustrating a moving direction of a human body with respect to a human body detection sensor.

FIG. 7 is a top view illustrating a state where a human body crosses a detection beam.

FIG. 8 is a side view illustrating a state where a human body is directed to a detection beam.

9A and 9B are diagrams illustrating a relationship between a moving direction of a human body and an output of an infrared detection element, wherein FIG. 9A illustrates a direction crossing a detection beam, and FIG. 9B illustrates a direction toward the detection beam.

[Explanation of symbols]

 2 Infrared detector 5 Judgment unit 5a First judgment unit 5b Second judgment unit 5c OR circuit

Claims (1)

[Claims] A detection unit that outputs a voltage value corresponding to a change amount of an infrared ray; and a first determination signal when an output of the detection unit exceeds the first threshold value. And a second threshold value lower than the first threshold value, and a second threshold value when the output of the detection unit exceeds the second threshold value a predetermined number of times within a predetermined period. And a second OR circuit for outputting a detection signal based on a logical sum of the first determination signal and the second determination signal. Sensor.