JPS6316283A - Human body detecting device - Google Patents

Abstract

PURPOSE:To discriminate the entry direction and distance of a human body through simple constitution by regarding a distance value as a background value and storing another area of a storage circuit when the distance value is unchanged for longer than a certain time. CONSTITUTION:An optical system 18 converges an infrared ray from an infrared-ray projector 11 in a beam shape by a lens 12 and projects it, and the reflected infrared ray from a body is converged again by a lens 14 and detected by an infrared-ray photodetector 15. A distance measuring circuit 19 consists of the optical system 18, a driving circuit 13 which drives the projector 11, an amplifying circuit 16, and an A/D converting circuit 17 and measures the distance to the body. A scanning part 20 can scan at least the optical system 18 within a constant angle range at intervals of a unit angle and distance values obtained at the intervals of the unit angle are stored in a storage circuit 21. Then, a CPU 22 regards the distance value as the background value when the distance value is kept unchanged for longer than the constant time and stored it in another area of the storage circuit 21, and the background value is subtracted from distance values which are obtained one after another to detect the entry direction and distance of the person.

Description

[Detailed Description of the Invention] Industrial Application Field The present invention detects the direction and distance of a person and controls the air blowing direction and air volume of a blower, and the human body used to determine the monitoring direction of a surveillance camera. The present invention relates to a detection device.

2. Description of the Related Art Conventionally, this type of human body detection device has a configuration as shown in FIG. In FIG. 4, reference numeral 1 denotes a pyroelectric detector whose electrical output changes in response to changes in the amount of infrared rays caused by the movement of a person. Infrared rays within a certain solid angle are focused and imaged onto the pyroelectric detector array 1 by the lens 2, so if there is a change in the amount of infrared rays due to the movement of a person within a certain small solid angle, the pyroelectric detector array 1 An electrical signal appears on a specific pyroelectric detector corresponding to that tiny solid angle above. 3 is an amplifier circuit for amplifying this weak electric signal. In other words, if a person moves within the solid angle determined by the optical constants of the lens 2, the output signal of the amplifier circuit 3 corresponding to that position changes moment by moment. 4 is a central control circuit for identifying which channel's output signal of the amplifier circuit 3 is changing, and a microprocessor or the like is used. The central control circuit 4 switches the multiplexer 5 at a fixed timing, sends the output signal of each channel of the amplifier circuit 3 to the A/D conversion circuit 6, issues a command to convert it into a digital value, and performs an operation to take in the converted value. . Newly collected amplifier 3
If the output signal value of a certain channel is above a certain level, the central control circuit 4 determines that there is a person in the minute solid angle direction corresponding to that channel.

Problems to be Solved by the Invention In such a conventional configuration, the pyroelectric detector array 1 is a sensor that applies the pyroelectric effect, so as long as there is a large change in the amount of incident infrared rays, it can be detected regardless of the distance from the person. Since it has the property of causing an output signal to appear, there is a problem in that although the direction in which a person is present can be detected, it is difficult to detect the person's position.

That is, the output signal level of the pyroelectric detector array 1 may be about the same when a person makes a slow movement at a short distance and when a person makes a sudden movement at a long distance.

The present invention is intended to solve these problems, and aims to provide a human body detection device that can identify the direction in which a person is located as well as the distance.

Means for Solving the Problem In order to solve this problem, the present invention provides an optical system for refocusing and capturing the reflected rays of infrared rays from an object that have been focused and projected into a beam; A distance measuring circuit that includes the system and measures the distance to the object, a scanning section that can scan at least the optical system at every unit angle within a certain angle, and a distance value that is stored at every unit angle. A storage circuit is provided, and when this distance value holds the same value for a certain period of time or more, it is regarded as a background value and stored in another area of the storage circuit, and this background value is subtracted from the distance value obtained every moment. The system is configured to detect the direction and distance of a person.

Effect With this configuration, objects whose direction and distance do not change for a certain period of time are considered stationary objects rather than people, so as time passes, the background, which is a collection of stationary objects, becomes clearer, This means that the direction and distance can be determined.

EXAMPLE An example of the present invention will be described below with reference to FIGS. 1 to 3. In FIG. 1, reference numeral 11 denotes an infrared projector, and the infrared rays projected by the infrared projector 11 are focused into a beam by a lens 12 and impinge on an object. 13
is a drive circuit for pulse-driving the infrared projector 11, and pulse-drives the infrared projector 11 using a modulated signal to eliminate the influence of ambient light. The infrared rays reflected by the object are refocused by the selenium lens 14 and enter the infrared receiver 16 .

Since the electrical signal converted by the infrared receiver 15 is weak, it is amplified by the amplifier circuit 16, and then
/D conversion circuit 17 converts it into a digital value.

Here, the infrared projector 11, lens 12, lens 14, and infrared receiver 15 are collectively referred to as an optical system 18, and the optical system 1
8. Drive circuit 13, amplifier circuit 16 and A/D conversion circuit 17
Since it collectively outputs distance information, it will be referred to as the distance measuring circuit 19. 2o is the minimum optical system 1
8 or the distance measuring circuit 19 at unit angle intervals within the angle to be measured, and can be realized by, for example, a motor and its drive circuit. 21 is a storage circuit 617 for storing digitalized distance information. 22 is a central control circuit that oversees a series of human body detection operations described below.

The central control circuit 22 first issues a command to the scanning section 2Q to cause the optical system 18 or distance measuring circuit 19 to scan by a unit angle. When the scanning is completed and the position of the optical system 18 or distance measuring circuit 19 is stabilized, a command is then issued to the infrared projector 13,
Projects infrared light onto an object. Thereafter, the amount of reflected infrared rays obtained through the lens 14, infrared receiver 15, amplifier circuit 16, and A/D conversion circuit 17 is input. In this embodiment, a distance measurement method is used in which the amount of reflected infrared rays is directly used as a distance value, but a distance measurement method using the principle of triangulation may also be used. The central control circuit 22 further compares the amount of reflected infrared rays, that is, the distance value, which has just been taken in, with the previously measured distance in the same direction, and if they are different, replaces the contents of the storage circuit 21 with a new distance value. If the distance value is the same as the previous time, the duration is updated. When this duration reaches a certain time, the distance value is determined to be the distance value to the stationary object due to reflection from the stationary object, and the background value is stored in a separate area from the current distance in the memory circuit 21. Store it as. Identification of whether there is a person in the direction currently being measured can be done by subtracting the background value from the collected distance value, and if there is a difference between the two, it can be determined that there is a person in the collected distance value. Shi, if it is the same, we can judge that there is no person, and we can get seven.

This is based on the fact that if the object is a person, it is extremely rare for an object to remain in the same place for a certain period of time, which is considered as a background value. When the human body detection operation in that direction is completed, the central control circuit 22 issues a command to the scanning section 20 again to start the distance measurement to the object in the next direction, that is, the human body detection operation.

In order to clarify the human body detection operation as described above, the second
This will be explained using the diagram and FIG. FIG. 2 is a timing diagram. In FIG. 2, a period T1 represents a period during which the human body detection operation in a certain direction is completed and the optical system 18 or distance measuring circuit 19 is scanned to the next direction. The signal S1 is a drive signal for the infrared projector, and the signal S2 is a drive signal for the infrared projector.
It is a reflected infrared signal that passes through the The amplitude of the reflected infrared signal, that is, the signal S2 changes depending on the distance from the object. Period T is a sampling period in which the maximum value of signal S2 is observed, and period T3 is a sampling period in which the distance value collected in period T2 is determined to determine whether the value is a background value that has continued for a certain period of time or more, and then the distance to the person is determined. This is the period for which .

FIG. 3 shows a specific example of human body detection, where the circle indicates a person and the hatched area indicates a stationary object. Note that human body detection is performed by determining where the human body is in six areas r and -r5 with respect to eight directions 01 to θ8. Also, each figure is a state diagram when the same value has passed for a certain time α or more, that is, from the top, time t1 time t+α, time t+2α, time t
Let us show a situation diagram of +2α. Area τ1 (i=1~
5) Assuming that the distance value is digitized with a value of 1 if there is a K object, and 0 if there is no object, the collected distance values, background values, and human body detection results for all directions of the entire situation map are summarized in the table below. It becomes like this.

The x indicates that the area is indeterminate because there is an object in the previous area.

Incidentally, in the above embodiments, infrared rays are used as the distance measuring medium, but the same operation can be performed using ultrasonic waves.

Effects of the Invention As described above, according to the present invention, the direction in which a person is located and the distance thereof can be identified with a simple configuration, although it requires the passage of a certain amount of time, and this has a great practical effect.

[Brief explanation of the drawing]

FIG. 1 is a circuit configuration diagram of a human body detection device according to an embodiment of the present invention, FIG. 2 is a timing diagram of the same, FIG. 3 is a diagram of the same specific situation, and FIG. 4 is a circuit configuration diagram of a conventional human body detection device. It is. 18...Optical system, 19...Distance measurement circuit,
20...Scanning unit, 21...Storage circuit.

Claims (2)

[Claims] (1) An optical system that refocuses and captures the reflected infrared rays from an object that are focused and projected into a beam, a distance measuring circuit that includes this optical system and measures the distance to the object, and a minimum of Only the optical system is equipped with a scanning unit that can scan every unit angle within a certain angle, and a memory circuit that stores distance values obtained at every unit angle, and this distance value remains the same for a certain period of time or more. When the human body detecting device detects a person, the human body detecting device is configured to treat this as a background value and store it in another area of the memory circuit, and to detect the direction and distance in which the person is present by subtracting this background value from the distance value obtained every moment. (2) The human body detection device according to claim 1, which uses ultrasonic waves instead of infrared rays and has an optical system as an ultrasonic wave transmitting/receiving system.