JPH07334765A - Light beam type body detecting device - Google Patents

Abstract

PURPOSE:To eliminate a disturbance factor and improve the detection precision by photodetecting reflected light from plural areas and outputting a detection signal when the arithmetic value based upon the quantity of reflected light and the reference quantity of reflected light is larger than a specific value in any one area. CONSTITUTION:This device is equipped with a light projecting means 1 which projects light on plural areas and a photodetecting means 2 which photodetects the reflected light from the respective areas. Then an arithmetic means 3 calculates the differences between the quantities of reflected light in the respective areas at a specific time and the reference quantities of reflected light determined by the areas from the output results of the quantities of reflected light of the photodetecting means 2, finds the mean value of the differences, and calculates the sums of the mean value and the reference quantities of reflected light of the respective areas and the differences between or the ratios of the mean value and the quantities of reflected light of the areas at specific intervals of time. When the difference or ratio exceeds the specific value in any one area, a decision means 4 outputs a detection signal. Consequently, even if the quantity of reflected light varies, the entry of a human body, etc., can surely be detected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light beam type object detecting device for detecting a moving object (such as a person) in a detection area in order to open and close an automatic door.

[0002]

2. Description of the Related Art Generally, in a light ray type object detecting device, a light ray is projected toward a plurality of areas, the reflected light is received for each area, and the amount of received light varies with a reference amount of light. It is configured to detect the entry of a human body or the like into the detection area when the threshold level is exceeded. With this configuration, the human body shown in FIG. 3 and the snowstorm shown in FIG. 4 are output without distinction, resulting in many malfunctions.

Therefore, for example, as in the case of PIR, a method of canceling a disturbance factor by looking at the difference between the outputs of a pair of areas is also used. When this method is adopted, for example, as shown in FIG.
When there is a large difference between the peak levels a1 and a2 shown in (1), the output exceeds the threshold level.

[0004]

However, in any of the above-mentioned conventional techniques, there is a problem that the difference in the waveform of the reflected light amount when the human body or the like enters and the disturbance cannot be detected, and the detection accuracy is unstable. there were.

The present invention has been made in order to solve these problems, and it is possible to cancel the fluctuation of the reflected light quantity due to the disturbance and detect only the fluctuation due to the movement of the human body. The purpose is to provide.

[0006]

In order to achieve the object of the present invention, the light beam type moving object detecting device of the present invention is directed to a plurality of areas as shown in the basic conceptual diagram of the present invention shown in FIG. A light projecting means 1 for projecting light and a light receiving means 2 for receiving the reflected light from each of the areas are provided. The difference between the amount of reflected light and the reference reflection amount determined for each area is calculated, and the average value of these differences is determined, and at each of the predetermined times, the average value and the reference reflection amount of each area. Calculation means 3 for calculating the difference or ratio between the respective sums and the amount of reflected light in the area, and a detection signal is output when the difference or ratio exceeds a predetermined value in any of the areas. Discrimination It is characterized by comprising comprises a stage 4.

[0007]

[Function] For a plurality of areas, the average value of the difference between the reflected light amount of each area and the reference reflection amount of each area at the same time is obtained, and the average value of the difference and the reference reflection amount of each area The detection signal is output only when the difference or ratio between the respective sums of the above and the amount of reflected light in that area is equal to or larger than a predetermined value in any of the areas.

[0008] Here, when a person advances toward the door,
As shown in FIG. 3, the waveform showing the change over time of the reflected light amount is different for each area, and the peaks appear with a time-series deviation. On the other hand, as shown in FIG. 4, the waveforms generated by disturbance factors such as snowstorms appear to have substantially the same shape at substantially the same time.

Therefore, in the waveform generated by the disturbance factor, there is almost no difference between the sum of the average value of the above-mentioned differences in each area and the reference reflection amount in each area and the reflected light amount in each area. When the object moves, a large difference occurs, so that it is possible to determine that the object is caused by a disturbance, and the movement of the person can be reliably detected.

[0010]

FIG. 2 is a diagram showing a state in which an embodiment of the present invention is installed. The light beam type moving object detection device 21 of the embodiment of the present invention is
It is provided above the door 22, and the device 21 is provided with a light projector (not shown) and a light receiver (not shown). The projector includes light emitting elements corresponding to the detection areas arranged in front of and behind the door 22, and the light receiver also includes light receiving elements corresponding to the detection areas. Reflected light is received by the light receiving element, and a processing unit for determining calculation and detection described below for the amount of reflected light is provided. The processing unit corresponds to a microcomputer or the like as the hardware configuration of the device.

The configuration of this processing unit will be described below. First, a case where a human body moves will be described with reference to FIGS. 5 and 6.

The sensitivities of the respective detection areas are substantially the same. FIGS. 5A, 5B, and 5C show changes with time of the reflected light amounts of the detection areas C, B, and A, respectively. Therefore, the change amount of the reflected light amount from the reference reflection amount at the predetermined time t ₁ is obtained, and the average value thereof is obtained. In addition, when calculating the variation | change_quantity in each area here, the reason that the reference reflection amount of each area is used is because the angle which sees an area differs for every area.

As shown in the figure, the reflected light amount and the threshold level at the time t ₁ of the detection areas C, B, A are (a1, s1), (a2, s2), (a3, respectively).
s3). From these, the result of obtaining the average value of the change amount of each area by the equation (1) is shown in FIG.

[0014]

[Equation 1]

Next, the average values thus obtained are respectively
When added to the reference reflection amount of each area, as shown in FIG.
In addition, the shape is indicated by a broken line. And the value shown by this dashed line
And the amount of reflected light corresponding to each area (d _c，
d_b,d_a) Is calculated. In this case, the difference is limited to
Alternatively, the ratio may be calculated.

As a result of obtaining the value of this difference or ratio, when this difference becomes large in any one of the detection areas C, B, A, or the value of this ratio exceeds a predetermined value, the human body The detection signal is output, and if not, the human body detection signal is not output because of disturbance. In the case of this embodiment, the difference (d _c , d _b, d _a ) is judged to be large in any area, and the human body detection signal is output.

Next, a case where the amount of reflected light changes with respect to the threshold level due to a disturbance such as snowstorm will be described with reference to FIGS. 7 and 8. 7A, 7B, and 7C show changes with time of the reflected light amounts of the detection areas C, B, and A, respectively.

By a calculation similar to the above, a predetermined time t ₁
Find the amount of change in the amount of reflected light from the reference amount of reflection at
Calculate the average value. As shown in the figure, the detection area C,
The amounts of reflected light and threshold levels of B and A at time t ₁ are (a1, s1), (a2, s2),
(A3, s3). From these, the result of obtaining the average value of the amount of change in each area by equation (1) is shown in FIG.

Further, when the average value thus obtained is added to the reference reflection amount of each area, the shape shown by the broken line is obtained as shown in FIG. Then, the difference between the value indicated by the broken line and the corresponding reflected light amount in each area is calculated. In this case, the ratio may be calculated without being limited to the difference.

As is clear from these figures, when the amount of reflected light exceeds the reference amount of reflection due to disturbance, the waveform showing the change in the amount of reflected light over time has substantially the same shape, and There is almost no difference between the amount of reflected light and the sum of the average value of the amounts of change and the reference amount of reflection. Therefore, the detection signal is not output.

As described above, in the embodiment of the present invention,
A predetermined time (t1) was selected, and calculation and determination were performed for that moment. However, as a method of storing each signal for a certain time in a memory, sampling a waveform with the data, and determining passage of a human body, for example, , 0.5 seconds or the like, and if the time exceeding the threshold level exceeds 80% within that time, it may be determined that the human body has passed. In this case, malfunction is further reduced.

[0022]

As described above, according to the light ray type object detection apparatus of the present invention, the light projecting means for projecting light toward a plurality of areas and the light reflected from each area are received. A light receiving unit is provided, and the difference between the reflected light amount of each area and the reference reflection amount of each area at a predetermined time is calculated to obtain an average value of these differences, and the average value and each Calculation means for calculating the difference or ratio between the sum of the reference reflection amount of each area and the reflected light amount of the area, and detection when the difference or ratio exceeds a predetermined value in any area Since the configuration is provided with a determination unit that outputs a signal, even if there is a change in the amount of reflected light, it is possible to eliminate the case where the disturbance is the cause, and it is possible to reliably detect the entry of the human body, etc. To improve It can be.

[Brief description of drawings]

FIG. 1 is a basic conceptual diagram showing the configuration of the present invention.

FIG. 2 is a diagram for explaining the installation situation of the embodiment of the present invention.

FIG. 3 is an operation explanatory diagram when a person moves in a detection area according to the embodiment of the present invention.

FIG. 4 is an operation explanatory diagram when a disturbance occurs in the detection area according to the embodiment of the present invention.

FIG. 5 is a diagram for explaining the operation when a person moves within the detection area according to the embodiment of the present invention.

FIG. 6 is a diagram for explaining an operation when a person moves in the detection area according to the embodiment of the present invention.

FIG. 7 is a diagram for explaining the operation when a disturbance occurs in the detection area in the embodiment of the present invention.

FIG. 8 is a diagram for explaining the operation when a disturbance occurs in the detection area in the embodiment of the present invention.

[Explanation of symbols]

 1 ... ・ Light emitting means 2 ... Light receiving means 3 ... Calculation means 4 ... Discrimination means 21 ... Light beam type moving object detection device

Claims (1)

[Claims] 1. A light projecting means for projecting light toward a plurality of areas and a light receiving means for receiving reflected light from each of the areas, and based on an output result of the reflected light amount by the light receiving means, The difference between the reflected light amount of each area in a predetermined time and the reference reflection amount determined for each area is calculated respectively, and the average value of these differences is obtained, and at each predetermined time, the average value and each area are calculated. And a calculation means for calculating a difference or a ratio between each of the reference reflection amount and the reflected light amount of the area, and when the difference or the ratio becomes a predetermined value or more in any of the areas. A light beam type object detection device comprising a determination means for outputting a detection signal.