JPH0651073A - Infrared object sensing device - Google Patents

Abstract

PURPOSE:To eliminate malfunction due to external turbulence and provide possibility of sensing of a stationary object by using polarized infrared rays to a source for infrared rays to be projected, and sensing the difference between reflected polarized infrared rays and a natural infrared beam when any object exists. CONSTITUTION:Infrared ray polarizing pieces 3, 5 and other ones 9, 7 transmit polarized infrared rays in respective identical polarization planes, while the polarizing pieces 3, 9 and the ones 5, 7 transmit polarized infrared rays whose polarization planes are different in 90 deg. Infrared projecting elements 2, 8 make light emission alternately with an oscillator 11 and inverter 12, and polarized infrared rays which the polarizing pieces 3, 9 have transmitted are reflected by an object to be sensed 1, and the resultant beam is sensed by either of the infrared sensing elements 4, 6 solely which thereupon give output signals alternately. If there is no object and a natural infrared beam is incident, sensing takes place with both elements 4. 6, which however are in such a connection that their outputs set off one another and do not emit any output signals. The reflected beam from the object 1, on the other hand, is emitted as a signal having an amplitude twice as large as the output of each element 4, 6. The output signal therefrom is wave detected 17 to form a signal corresponding to the object 1. Accordingly there is no malfunction due to external turbulence any more.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an object detection device for operating an automatic door opening / closing device, an in-room confirmation device, an automatic faucet device and the like.

[0002]

2. Description of the Related Art Conventionally, as a method of detecting an object using infrared rays, a method of detecting an object by projecting infrared rays on the object and detecting infrared rays reflected from the object (hereinafter referred to as AIR) And a method of detecting an object (hereinafter referred to as PIR) by detecting infrared rays (hereinafter referred to as heat rays) corresponding to the temperature of the object emitted from the object. Has been done. The former is able to detect stationary objects, but light with strong energy such as sunlight has large energy even in the infrared region, so when these lights enter the detector, There are drawbacks such that the presence of an object cannot be detected (hereinafter, referred to as false alarm), or a detection signal is output even when there is no object (hereinafter, referred to as false alarm). On the other hand, the latter includes a pyroelectric type heat ray detection element as an element for detecting heat rays emitted from an object (hereinafter referred to as a heat ray detection element), but in that case, detection of a stationary object is difficult. ,Sun light,
False alarms can be avoided if the temperature of the environmental background becomes similar to the temperature of the sensing object due to the effect of wind, etc., or if light with strong energy such as sunlight enters the detector. It has the drawback of not having it.

As a method which has been carried out in order to improve the above-mentioned drawbacks, an AIR utilizing a trigonometric method as disclosed in JP-A-62-204113 and JP-B-02-45238.
There is a method that uses both the PIR and the object detection method using ultrasonic waves. However, the former has a very narrow detection area and is limited in its intended use. The latter has a PIR.
However, both of the object detection methods using ultrasonic waves have a problem that malfunctions are caused by wind.

[0004]

As described above, there is provided an infrared type object detection device capable of detecting a stationary object without a malfunction such as a false alarm or a false alarm due to a disturbance such as sunlight or wind and having a wide range of use. This is the problem to be solved by the present invention.

[0005]

The present invention has been made to solve the above problems. The means is to use artificially polarized infrared rays (hereinafter referred to as polarized infrared rays) as a projection infrared source in AIR, and to exist in the natural world with the polarized infrared rays reflected when an object exists. It is configured to detect a difference from random infrared rays (hereinafter, referred to as natural infrared rays) (hereinafter, referred to as polarization AIR). Furthermore, it is necessary to perform arithmetic processing to perform more advanced object detection, and to add PIR to obtain a wide variety of signals for use in the arithmetic processing.

[0006]

1 is a schematic diagram showing the principle of the present invention configured as described above. In this figure, the directions of the arrows in the infrared polarizers (3), (5) and (7) represent the polarization directions of the infrared polarizers. First, consider the case where there is a detection target (1) as shown in FIG. The infrared projection element (2) and the infrared polarizer (3) project polarized infrared light onto the detection target (1). Since the infrared rays reflected from the detection target (1) are polarized infrared rays having the same polarization plane as the projected polarized infrared rays, the infrared polarizer (3)
Infrared polarizer with the same polarization direction (5)
Can be transmitted, but the infrared polarizer (7) whose polarization directions are different by 90 ° cannot be transmitted. Therefore, the infrared detection element (4) detects a signal, but the infrared detection element (6) does not detect a signal. Next, consider the case where natural infrared rays are incident as shown in FIG.
Infrared polarizer (3) because natural infrared rays are not polarized
Both of (5) have different polarization plane directions, but the same amount of polarized infrared light can be transmitted. Therefore, the infrared detection elements (4) and (6) both detect signals of the same magnitude.
Here, the infrared detection elements (4) and (6) are configured to compensate each other to remove the influence of natural infrared rays and detect only the polarized infrared signals reflected by the detection target (1). It is possible. Further, by using a plurality of infrared projection elements and a plurality of infrared polarizers, it is possible to project polarized infrared light having a polarized plane by projecting the polarized infrared light having a polarizing plane with a temporal shift. . Since polarized infrared rays whose polarization planes change cannot exist in nature, by configuring a means for detecting only polarized infrared rays whose polarization planes change, the S /
N can theoretically be infinite. Furthermore, by using the heat ray detecting means as in the second aspect and using the electric circuit or the electronic circuit as in the third aspect, the signal processing is performed in time series, and the accuracy of the automatic sensitivity adjustment of the polarization AIR is further improved. It is possible to perform object detection with improved performance.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An infrared object detecting apparatus according to the present invention will be described in detail below with reference to the drawings. FIG. 2 is a block diagram of an infrared type object detection device showing an embodiment of the present invention, and FIG. 3 is a time chart based on FIG. The infrared polarizers (3), (9), (5) and (7) are respectively provided on the front surfaces of the infrared projection elements (2) and (8) having the same characteristics and the infrared detection elements (4) and (6) having the same characteristics. Is installed. In this case, the infrared polarizer (3) (5) and the infrared polarizer (9)
With respect to (7), polarized infrared rays in the same plane direction are transmitted, and polarized infrared rays whose polarization plane directions are different from each other by 90 ° are transmitted. Infrared projection element (2) (8)
By the oscillator (11) and the inverter (12)
Light is emitted alternately as shown in FIGS. 3C and 3D, and the light emission intensity is controlled by the arithmetic circuit 18, the light emission output control circuit 13, and the drive circuit 10. The alternately output infrared rays are respectively polarized by the infrared polarizers (3) and (9). Therefore, the polarization plane is 90 at the oscillation frequency of the oscillator (11) toward the detection target (1).
° Changing polarized infrared rays will be projected. Since such polarized infrared rays do not exist in nature, the S / N ratio is theoretically infinite with respect to various disturbances by configuring a means for detecting only the polarized infrared rays.

Here, consider the case where there is a detection target (1). When infrared rays are projected from the infrared projection element (2), the polarized infrared rays that have passed through the infrared polarizer (3) are reflected by the detection target (1). Since this reflected infrared ray is also a polarized infrared ray having the same plane of polarization as the projected polarized infrared ray, it is detected only by the infrared detecting element (4). On the other hand, when projected from the infrared projection element (8), it is detected only from the infrared detection element (6). Therefore, the infrared detecting elements (4) and (6) alternately output signals as shown in (A) of FIGS. Moreover, the detection target (1)
If there is no light and natural infrared rays enter the infrared detector,
It is detected by both the infrared detection elements (4) and (6) as shown in (B) of FIGS. Here, since the infrared detection elements (4) and (6) are connected so as to cancel their outputs, no signal is output in the latter case as in (b) of FIG. 3 (G), but in the former case. As shown in (a) of FIG. 3 (G), a signal having the same frequency as the oscillation frequency of the oscillator (11) and having an amplitude twice that of the output of each infrared detection element is output. This is the same even when the detection target (1) and natural infrared rays are mixed, and only the polarized infrared light reflected from the target is output as shown in (c) of FIG. The DC component of this signal is completely removed by using the circuit using the operational amplifier (14) and the inductor (15). Next, a frequency component other than the same frequency component as the oscillation frequency of the oscillator (11) is removed through a bandpass filter (hereinafter referred to as BPF) (16) and passed through a detection circuit (17). It is possible to obtain a signal corresponding to the presence of the detection target (1) as shown in FIG. Further, a signal obtained by the heat ray detecting element (20), an amplifier (21) that amplifies and processes the signal, and a signal obtained by the comparator (22) and the above-mentioned signal are calculated by an arithmetic circuit (18). This utilizes the feature of the heat ray detecting element (20) that there is almost no false alarm, and automatically controls the light emission output when there is no detection target (1) so that the detection ability is always optimized. As described above, by processing each signal in time series, more advanced functions can be realized. The calculation circuit (18) outputs the calculation result as a signal corresponding to the presence of the detection target (1) in the alarm circuit (19). Here, the infrared rays to be projected are polarized using the infrared polarizers (3) and (9), but may be polarized by another method. Although the number of infrared projection elements is two here, it may be one or three or more, and the infrared polarizer for polarizing the projected infrared rays in that case may be one or plural. Here, the infrared rays projected from the infrared ray projection elements (2) and (8) have a pulse waveform, but other waveforms may be projected. In addition, the infrared projection element and the infrared detection element may perform modulation and demodulation.
The means is not particularly limited. Although the method described above is used here as the signal processing method, another method, for example, a method using a computer may be used.

[0009]

As described above, the present invention is
It is industrially valuable in that it is possible to provide an infrared object detection device that can detect a stationary object and has a wide range of use, without malfunctions such as false alarms and false alarms due to disturbances such as wind.

[0010]

[Brief description of drawings]

FIG. 1 is a schematic diagram showing the principle of the present invention.

FIG. 2 is a block diagram of an infrared type object detection device showing an embodiment of the present invention.

FIG. 3 is a time chart based on FIG.

[Explanation of sign]

 1 Detection Target 2 Infrared Projection Element 3 Infrared Polarizer 4 Infrared Detector 5 Infrared Polarizer 6 Infrared Detector 7 Infrared Polarizer 8 Infrared Projector 9 Infrared Polarizer 10 Drive Circuit 11 Oscillator 12 Inverter 13 Light Emission Control Circuit 14 Operational Amplifier 15 inductor 16 band pass filter (BPF) 17 detection circuit 18 arithmetic circuit 19 reporting circuit 20 heat ray detection element 21 amplifier 22 comparator

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Masato Arioka 4 372 Unoyama, Tottori-shi, Tottori Japan Ceramics Co., Ltd.

Claims (3)

[Claims] 1. An infrared projection means for projecting polarized infrared light onto an object, an infrared detection means for detecting infrared light having the same polarization plane as the polarized infrared light reflected by the object, and the infrared detection means. And an infrared detecting means for detecting an infrared ray having a polarization plane different from the polarized infrared ray detected by the infrared type object detecting device. 2. The infrared object detection device according to claim 1, further comprising infrared detection means for detecting infrared light emitted from the object and corresponding to the temperature of the object. 3. The infrared type object detection device according to claim 1, further comprising an electric circuit or an electronic circuit that individually or compositely processes the signal from the detection means.