JPH03289582A - Detecting apparatus for object - Google Patents

Abstract

PURPOSE:To detect an object without imparting the impression monitored by a camera by intermittently irradiating the object to be detected with far infrared rays and detecting the reflected infrared rays from the object to confirm the presence of the object. CONSTITUTION:A lens 24 formed from material quality opaque in a visible region permitting far infrared rays to pass is fitted to the entire surface of a case 20 and acts so as to condense the far infrared rays from a light emitting element 21 in a beam like form to project the same in the direction of an object (e.g., person) 25 to be detected. Further, the lens 24 acts so as to condense the reflected infrared rays from the object to be detected to project the same on a photodetector 22. Therefore, material quality opaque in a visible region can be used as that of the lens or window plate covering the light emitting element and the photodetector and the impression monitored by a camera is not imparted.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an object detection device, and in particular, it emits a pulsed far-infrared beam toward an object, and detects the infrared rays reflected by the object to be detected. is received by a pyroelectric element,
The present invention relates to an object detection device that detects the presence of an object.

[Conventional technology]

Generally, methods for detecting the presence of an object include, for example, emitting near-infrared rays close to the visible range from a light-emitting element such as an LED onto the object and monitoring the reflected light, or detecting infrared rays emitted from the object itself. Detection means using a light receiving element, etc. have been proposed and put into practical use.

FIG. 5 illustrates a conventional example of the former. That is, 1 is a light emitting element such as an LED that emits near-infrared light close to the visible region, and 2 is a light projection control circuit that controls the light emission of this LED 2. Further, 3 is a transparent projection lens attached to the entire surface of the case 4 in which the LED 1 is arranged.

On the other hand, 5 is an infrared light receiving element placed inside the case 6, and 7 is a transparent condenser lens attached to the entire surface of the case 4. Reference numeral 8 denotes a light reception processing circuit that amplifies the electric signal from the infrared light receiving element 5 and generates a detection output.

In the configuration of FIG. 5 described above, when a control signal is generated from the light projection control circuit 2, the light emitting element 1 emits near infrared rays close to the visible region.

This near-infrared rays are transmitted through the projection lens 3 to the detected object 9 (
For example, the beam is projected onto the human body.

The infrared rays reflected by the object 9 are condensed by the condensing lens 7 and photoelectrically converted by the infrared receiving element 5. The electrical output is amplified by the light reception processing circuit 8, and a detection output is generated from the output terminal 10.

Next, FIG. 6 illustrates an example of the latter conventional method.

In other words, 11 is the case of the device, and on its entire surface,
An opaque window plate 12 is attached.

In addition, inside the case 11, a parabolic reflector] 3
is arranged, and a pyroelectric element 14 is arranged roughly at the focal point of the reflecting plate 13.

The pyroelectric element 14 is connected to a light reception processing circuit 15 that amplifies the electrical output obtained from the pyroelectric element 14.

In the configuration of FIG. 6 described above, the detected object 16 (
Infrared rays emitted from, for example, a human body pass through a window plate 12, are focused by a reflector plate 13, and are received by a pyroelectric element 14.

The electrical output from the pyroelectric element 14 is transmitted to the light receiving processing circuit 1.
5 and a detection output is generated from the output terminal 17.

[Problem to be solved by the invention]

According to the conventional object detection device shown in FIG. 5, it is possible to detect both stationary objects and moving objects. However, since LEDI emits near-infrared rays close to the visible range, each lens 3 and 7 can only be made of a transparent material, giving the impression that they are being monitored by a camera.

Furthermore, according to the conventional object detection device shown in FIG.
In order to detect far-infrared rays emitted from the human body, the window plate 12 can be made of an opaque material, but since the light-receiving element is a pyroelectric element, only the differential amount of infrared rays emitted from the human body can be detected. It is impossible to detect the presence of a human body in such a state. The object of the present invention is to provide an object detection device that can detect the presence of both moving and stationary objects.

[Means to solve the problem]

The object detection device of the present invention, which has been achieved to achieve the above object, includes a light-emitting element drive circuit that generates an intermittent drive output, and a far-field sensor that is driven by the light-emitting element drive circuit and generates far-infrared rays intermittently. an infrared light emitting element, a far infrared light receiving element that generates an electrical signal by receiving reflected light of the far infrared light generated by the far infrared light emitting element, and an amplification that amplifies the electrical signal obtained by the far infrared light receiving element. The present invention is characterized in that it includes a circuit and a level detection circuit that generates an output according to the output level from the amplifier circuit.

[Effect]

According to the object detection device configured as described above, the presence of the object is detected by intermittently irradiating the object to be detected with a far-infrared beam and detecting the infrared rays reflected by the object.

For this reason, the window plate or lens that covers the light-emitting element and the light-receiving element can be made of a material that is opaque in the visible range, so it does not give the impression that it is being monitored by a camera, etc., and it can be It is also possible to detect objects that are

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing the configuration of a light emitting element and a light receiving element unit in an object detection device of the present invention.

In the figure, 20 is a box-shaped case, and inside this case 1, a far-infrared light emitting element 21 and a light receiving element 22 are installed on a partition wall 2.
They are separated from each other by 3. As the far-infrared light emitting element 21, for example, a thermal head used in a thermal printer or the like can be used.

A lens 24 made of a material that is opaque in the visible range through which far infrared rays pass is attached to the entire surface of the case 20, and this lens 24 is attached to the light emitting element 21.
The far infrared rays emitted from the sensor are focused into a beam and projected in the direction of an object (for example, a human body) 25 to be detected. Roughly speaking, the lens 24 functions to condense infrared rays reflected by the object to be detected and project the collected infrared rays onto the light receiving element 22.

FIG. 2 is a sectional view showing another example of the light emitting element and light receiving element unit in the object detection device of the present invention.

In the example shown in FIG. 2, a reflective mirror is used instead of a condensing lens to condense infrared rays, and the same functional parts as in FIG. 1 are designated by the same reference numerals.

That is, 26 is a reflecting mirror placed on the rear surface of the light emitting element 21 and the light receiving element 22, which has two parabolic curved surfaces, and the light emitting element 21 and the light receiving element 22 are placed at the respective focal positions. There is.

Further, a cover 27 is made of a material that is opaque in the visible range, and is attached to the front surface of the case 20 to protect the light emitting element 21, the light receiving element 22, and the reflecting mirror 26.

FIG. 3 is a block diagram showing a drive and signal processing unit connected to the light emitting element and light receiving element units shown in FIGS. 1 and 2.

In FIG. 3, 28 is an oscillation circuit, and this oscillation circuit 28 can generate intermittent pulses.

The pulse output from the oscillation circuit 28 is transmitted to the light emitting element drive circuit 2.
9, the far infrared light emitting element 21 is driven by the output of this drive circuit 29, and from the light emitting element 21,
Far infrared rays are emitted intermittently.

On the other hand, infrared rays reflected by an object to be detected 25 such as a human body are converted into an electrical signal by the light receiving element 22 and amplified by the amplifier 30.

The output amplified by the amplifier 30 is integrated by an integration circuit 31, and the output integrated by the integration circuit 31 is applied to a level detection circuit 32, which generates an output above a predetermined threshold level. .

The output from the level detection circuit 32 is amplified by the output circuit 33 and output from the output terminal 34.

With the above configuration, far infrared rays driven by pulse output from the oscillation circuit 28 and intermittently emitted from the light emitting element 21 are reflected by the object to be detected 2S and received by the light receiving element 22. The level of the electrical signal converted by the light receiving element 22 is detected by a level detection circuit 32, and an output is generated when the electrical signal is at a predetermined level or higher.

FIG. 4 shows another embodiment of the invention.

In FIG. 4, the same reference numerals as those in FIG. 3 above indicate the same parts, and the explanation thereof will be omitted for the sake of convenience.

In this FIG. 4, a sample-and-hold circuit 35 is used up instead of the integrating circuit 31 in FIG. 3.

This sample-and-hold circuit 35 operates to introduce the pulse output from the oscillation circuit 28 as a sampling pulse, and sequentially hold the output of the amplifier 30 that amplifies the electrical signal from the light receiving element 22 at the generation timing of the sampling pulse. .

Therefore, the bold outputs are sequentially applied to the level detection circuit 32, which generates an output above a predetermined threshold level.

According to the configuration shown in FIG. 4 described above, since the light reception output is held in synchronization with the lighting of the light emitting element 21, it is possible to provide an object detection device having a stronger detection ability against disturbances.

〔Effect of the invention〕

As is clear from the above description, according to the object detection device of the present invention, far infrared rays are intermittently projected by the pulse output obtained by the oscillation circuit, and the infrared rays reflected from the object are detected and the level detection circuit detects the infrared rays. The presence of an object is confirmed by detecting a reflection state higher than the level.

For this reason, the lens or window plate that covers the light emitting element and the light receiving element can be made of a material that is opaque in the visible range, and therefore does not give the impression that it is being monitored by a camera or the like.

Furthermore, since it utilizes the reflection of infrared rays that can be pulsed, it is possible to detect stationary objects, and the above-mentioned problems of the conventional devices can be eliminated.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing one embodiment of the light receiving and light emitting element unit used in the object detection device of the present invention, FIG. 2 is a sectional view similarly showing another embodiment, and FIG. FIG. 4 is a block diagram showing another embodiment of the driving and signal processing unit connected to the light emitting element unit, and FIG. 5 is a block diagram showing another embodiment of the same, and FIG. The block diagram shown in FIG. 6 is a block diagram showing another conventional example. 21... Light emitting element, 22... Light receiving element, 25...
Object to be detected, 28...Oscillation circuit, 29...Drive circuit, 30...Amplifier, 31...Integrator circuit, 32...
Level detection circuit, 33...output circuit, 34...-output end, 35...-sample/hold circuit.

Claims (1)

[Claims] a light emitting element drive circuit that generates intermittent drive output;
A far-infrared light-emitting element that is driven by the light-emitting element drive circuit and intermittently generates far-infrared rays, and a far-infrared light-receiving element that generates an electrical signal by receiving reflected light of the far-infrared rays generated by the far-infrared light-emitting element. An object detection device comprising: an amplifier circuit that amplifies the electrical signal obtained by the far-infrared light receiving element; and a level detection circuit that generates an output depending on the output level from the amplifier circuit. .