JPH07104415B2 - Human body detection device - Google Patents

Description

TECHNICAL FIELD The present invention relates to an infrared ray receiving type human body detecting device for detecting a human body by infrared rays emitted from the human body.

[Prior Art] An infrared ray receiving type human body detecting device detects a difference in infrared energy amount between a human body and a background (that is, a temperature difference between the human body and the background) by using an infrared detecting element such as a pyroelectric element. Then, the human body is detected, which has been widely spread in recent years, and along with this, improvement in reliability has been demanded. Possible causes of malfunction of the infrared ray detection type human body detection device are a temperature change in the background in the detection area, internal noise, and influence of disturbance light having large energy such as headlights and sunlight. Therefore, in order to eliminate these malfunction factors, various proposals have been conventionally made. As one of them, there has been proposed a method for detecting a human body by obtaining two sets of differential outputs by using four infrared detecting elements (JP-A-58-213396 or JP-A-59-94094). Gazette). An example of the detection operation of this human body detection device will be described with reference to FIGS. 3 and 4. In this human body detection device, four detection areas 1 to IV are set on the background, and infrared detection elements A ⁺ , A ⁻ , B ⁺ , B ^{− which} receive infrared rays from these detection areas I to IV, respectively.
Comprising a detection region I, IV and detection area II, each differential output Va for each III ^{- +} and Vb (infrared detection element B (infrared detection element A ^+, A output difference between), B ^- the output difference between ) Get. Fig. 3 (a)
As shown in, the human body M is detected from detection areas I and III to detection areas II and IV.
4A, the differential outputs Va and Vb shown in FIG. 4A are obtained, and the human body M is detected in the detection area as shown in FIG. 3B.
When moving from I and II to the detection regions III and IV, the differential outputs Va and Vb shown in FIG. 4B are obtained.

By the way, in this human body detecting device, for example, when the human body M diagonally crosses the four detection regions I to IV as shown in FIG. 3C, the differential output Va is obtained as shown in FIG. 4C. However, in the detection areas II and III, since the human body M crosses at the same time, the output is canceled and the differential output Vb does not occur. Therefore, in order to reliably detect the movement of the human body M with this human body detection device,
It is necessary to determine that the human body exists when either of the differential outputs Va and Vb produces an output. However, when the human body M is detected in this way, one of the differential outputs Va and Vb produces an output due to a temperature change occurring in one detection area, internal noise produced in one infrared detection element, or the like, and a malfunction occurs. There was a problem that caused.

Therefore, in order to solve the above-mentioned problems, the present inventors have proposed a human body detection device that detects the human body by comparing the outputs of a plurality of infrared detection elements (Japanese Patent Application No. 62-242090).
issue). FIG. 5 shows the overall structure of this human body detecting apparatus. This human body detecting device includes a plurality of infrared rays, each of which is made up of a plurality of detection areas A'to D ', and receives infrared rays from an area sufficiently smaller than the human body M through an optical system 1 for condensing each of the detection areas. Infrared detection unit 2 including detection elements A to D, amplification unit 3 that independently amplifies each output of each infrared detection element A to D, and signal processing unit 4 that converts the amplified output into a signal suitable for human body detection. And a determination unit 5 that detects the peak value and the output time of the converted signal and compares them with each other to determine the presence or absence of a human body, and an output unit 6 that outputs the determination result.

The operation of the human body detecting device will be described with reference to FIGS. 6 and 7. In this human body detection device, the human body M passing through this area is irrelevant in the moving direction by narrowing the area composed of the plurality of detection areas A'to D'to a sufficiently smaller area than the human body M as described above. However, when the human body M passes through the detection areas A'-D ', the peak values V _A -V of the respective outputs of the infrared detecting elements A-D are passed. _D is almost the same value. Therefore, the fact that the peak values V _{A to} V _{D of the} outputs of the infrared detection elements A to _D show almost the same value can be the first determination condition for the presence determination of the human body M. However, in reality, there are some variations in the peak value of each output of the infrared detecting elements A to D due to the temperature distribution on the surface of the human body M, and the peak value V _{A to} V _D of each output is affected by the ambient temperature. Therefore, regarding the presence determination, the presence determination of the human body M is performed by relatively comparing the outputs of the infrared detection elements A to D. Now, assuming that the maximum value of the peak values V _{A to} V _D of each output of the infrared detection elements A to _D is Vmax and the minimum value is Vmin, the ratio between Vmax and Vmin is less than a predetermined value S (0 <S <1). If larger, each peak value V _A ~
It is determined that the variation in V _D is small and the human body M exists.
That is, the first determination condition for determining the presence of the human body M is expressed as follows.

Vmin / Vmax> S (1) However, 0 <S <1 Further, when the human body M passes through the detection areas A'to D ', all the detection areas A'to D'regardless of the moving direction. There is no possibility of intruding at the same time. That is, there is a time difference between the times at which the output signals of the infrared detection elements A to D rise (hereinafter, this time is referred to as the output time) t _{A to} t _D. Therefore, the presence of a time difference between the output times t _{A to} t _D can be the second determination condition for determining the presence of the human body M. The time difference is limited to a certain range in consideration of the size of the detection areas A ′ to D ′ and the moving speed of the human body M. Therefore, if the time difference between the output times t _{A to} t _D is Δt,
The second determination condition for determining the presence of the human body M shown by the following equation is obtained.

Tmin <Δt <Tmax (2) where Tmin and Tmax are the lower limit value and the upper limit value of the time difference, respectively. For example, when the outputs of the infrared detecting elements A to D shown in FIGS. 7A to 7C are obtained, the time difference Δt = t _D −t _A can be obtained in any case.

That is, in this human body detecting device, the infrared detecting element A
It is determined that the human body M exists when the peak values V _{A to} V _D of each output of _D to _D are substantially constant and the output times t _{A to} t _D of each output have a variation in a predetermined range. When the presence / absence of the human body M is determined in this manner, malfunction due to the influence of general temperature change, ambient light such as sunlight, or local temperature change or internal noise can be prevented, and a highly reliable human body detection device Becomes

[Problems to be Solved by the Invention] By the way, in this human body detection device, each infrared detection element A to
The output time of D was detected by the determination unit 5 as the time when those output levels exceeded a predetermined determination value. Here, the time required for the human body M to pass through the detection areas A ′ to D ′ is inversely proportional to the moving speed of the human body M, and the second time of the presence determination of the human body M is determined.
The lower limit value Tmin of the determination condition (equation (2)) is set based on the output time difference of the infrared detecting elements A to D obtained by the human body M moving at the maximum speed. Therefore, in such an output time detection method, it is necessary to set the determination value low in order to accurately detect the human body M moving at high speed. In this human body detection device, for example, 360 m / h
The human body M moving from 0.1 m) to 36 km / h (10 m / s) is detected.

However, when the determination value for detecting the output time is set low as described above, for example, noise having different output times and different peak values (for example, element noise such as popcorn noise or electrical noise such as relay noise) is generated. ) Is input to the determination unit 5, the first and second determination conditions may both be satisfied, which may cause malfunction due to noise. In other words, if the judgment value is set low,
It reacts to noise.

The present invention has been made in view of the above points, and an object of the present invention is to provide a human body detection device that is less likely to malfunction due to noise.

[Means for Solving the Problems] In order to achieve the above object, the present invention is such that the peak value of each output of the infrared detection element is substantially constant, and the difference in the output time of each output is within a predetermined range, A determination unit that determines that a human body exists when the duration of each output is equal to or greater than a predetermined value is provided.

[Operation] According to the present invention, as described above, the determination unit determines whether or not the peak value of each output of the plurality of infrared detection elements is substantially constant and the output time of the output has a variation in a predetermined range. In addition, by determining whether the duration of each output of the infrared detection element is equal to or more than a predetermined value, the noise of which the duration is narrower than the output of the infrared detection element is the output of the infrared detection element. Do not judge, output time is different,
Moreover, it is designed so as to prevent malfunction due to noise having different peak values.

[Embodiment] The human body detecting apparatus of the present embodiment is structurally the same as the conventional human body detecting apparatus shown in FIG. 5, and in the case of the present embodiment, the determination unit 5 is used.
The method is characterized by the method of determining the presence of the human body M by. In the following description, the case where four infrared detecting elements are used will be described, but the present invention can be applied even when the number of infrared detecting elements is other than four.

First, a description will be added regarding the specific configuration of the present embodiment. In this embodiment, an inexpensive pyroelectric element that can operate at room temperature is used as the infrared detecting element. A thermopile may be used instead of the pyroelectric element. As the optical system 1, a mirror or a lens is used, and more specifically, a multi-division mirror or a multi-division lens is used. The infrared detection elements A to D are arranged on the focal plane of the optical system 1, and four detection areas A ′ to D ′ are arranged on the background through the optical system 1 in the same arrangement as the infrared detection elements A to D. Will be formed in. Here, when the human body M passes through the detection areas A'to D ', the infrared detection elements A to D produce outputs corresponding to changes in the temperature difference between the human body M and the background. The signal processing unit 4 is composed of a bandpass filter, a multiplexer and an A / D converter. The bandpass filter extracts only necessary frequency components in the outputs of the infrared detection elements A to D, and the bandpass filter is used by the multiplexer and the A / D converter. The outputs of the infrared detection elements A to D that have passed through the filter are sequentially A / D converted.

By the way, also in the determination unit 5 of the present embodiment, the output times t _{A to} t _D and the peak values V _{A to} V _D are calculated from the outputs of the infrared detection elements A to D processed by the signal processing unit 4, and It is determined whether or not the determination conditions of the expressions (1) and (2) are satisfied. In the case of the present embodiment, in addition to this, the duration of the output of the infrared detection elements A to D is predetermined. It is determined whether or not there is a value or more. That is, the human body M is detected in the detection areas A ′ to D ′.
When it passes through, it always enters first and then exits, so that the outputs of the infrared detection elements A to D have positive and negative polar points as shown in FIG. 2 and pass through the detection areas A'to D '. The output waveform has a duration that is only the time required for and the convergence time. Therefore, the outputs of the infrared detecting elements A to D and the noise such as popcorn noise can be discriminated from the duration of the input signal of the judging section 5. Therefore, in the present embodiment, the determination of the duration is the third determination condition for determining the presence of the human body M. This can be expressed as

W _A −W _D > Wth However, Wth is a determination value or less. A method of determining the presence of the human body M by the determination unit 5 of the present embodiment will be described below. The determination unit 5 of this embodiment detects the output times of the outputs of the infrared detection elements A to D from the time when their output levels exceed a predetermined determination value. However, this determination value is set to a value that can reliably detect the human body M moving at high speed. Then, it is determined whether or not the output times of the outputs of the infrared detection elements A to D satisfy the second determination condition (equation (2)). Here, when the above determination condition is not satisfied, it is determined that the human body M does not exist. When the second determination condition is satisfied, the peak value of the output of each infrared detection element A to D is obtained, and it is determined whether or not the first determination condition (equation (1)) is satisfied. Also in this case, if the above determination condition is not satisfied, it is determined that the human body M does not exist. Then, when the first determination condition is satisfied, it is determined whether or not the third determination condition is satisfied. That is, it is detected whether or not the durations W _{A to} W _D of the outputs of the infrared detection elements A to _D exceed the predetermined value Wth, and if it exceeds the predetermined value Vth, it is determined that the human body M exists. That is, in the present embodiment, the first
When all the third determination conditions are satisfied, it is determined that the human body M exists, and the output unit 6 outputs a human body detection output (for example, an alarm) as a determination result.

EFFECTS OF THE INVENTION As described above, in the present invention, the determination unit determines whether or not the peak value of each output of the plurality of infrared detection elements is substantially constant and the output time of the output has a variation in a predetermined range. In addition to that, since it is determined whether or not the duration of each output of the infrared detection element is a predetermined value or more, noise of the infrared detection element whose duration is narrower than the output of the infrared detection element is detected. It is not judged to be output, and it does not malfunction even if the output time is different and the peak value is substantially constant.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of one determination condition for determining the presence of a human body according to an embodiment of the present invention, FIG. 2 is an output waveform diagram of an infrared detection element, and FIG. 3 is an explanatory diagram of a conventional human body detection method. FIG. 5 is an output waveform diagram of the same as above, FIG. 5 is a block diagram showing the configuration of another conventional example, FIG. 6 is an explanatory diagram of the human body detecting method of the same as above, and FIG. Reference numeral 5 is a determination unit, and A to D are infrared detection elements.

Claims (1)

[Claims] 1. A plurality of infrared detecting elements, each of which detects infrared rays from an area which is composed of a plurality of detecting areas and is sufficiently smaller than a human body, for each detecting area, and a peak value of each output of these infrared detecting elements. A human body detection device including a determination unit that determines that a human body is present when the output time difference of each output is substantially constant and within a predetermined range, and the duration of each output is a predetermined value or more. .