JPH11240452A - Photo detection unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photo detection, allowing installation with a short cable and easy adjustment of optic axis, and with a wide detection area. SOLUTION: In this photo detection unit, detection areas 31, 32 configure an area for a detected object. A light transmitter 11 and a light receiver 12 are placed at one side of the detection area 31. Reflectors 131 to 133 are placed at the other side of the detection area 31, and a plurality thereof are provided for the pair of light transmitter 11 and light receiver 12. The reflectors 131 to 133 are placed at a distance from each other. A detecting part 1 configures light routes 141 to 143 along which light transmitted from the light transmitter 11 travels through the detection area 31, one of the reflectors 131 to 133, and the detection area 31 in order, and enters the light receiver 12. A detection portion 2 is configured similarly as the detection part 1. A signal processing part 4 detects if an object is detected in the detection areas 31, 32 by encoding a signal supplied from the light receivers 12, 22.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an optical sensing device.

[0002]

BACKGROUND OF THE INVENTION Optical sensing devices are used in various technical fields. For example, on a railroad crossing, a pedestrian, a car, and the like meet a train, so that it is used as a railroad crossing obstacle detecting means for preventing an accident.

[0003] When an optical detection device is used as a level crossing obstacle detecting means, conventionally, a light transmitter is arranged on one side of a level crossing, and a light receiver is arranged opposite to the other side of the level crossing. An optical sensing device of the form was used. In the transmission type optical detection device, if there is no obstacle between the light transmitter and the light receiver, the light transmitted from the light transmitter is received by the light receiver, but if there is an obstacle, The light transmitted from the light transmitter is not received by the light receiver, or the light reception level decreases. The signal processing unit detects the presence or absence of an obstacle in the level crossing by decoding the signal supplied from the light receiver.

One of the problems of the above-mentioned conventional optical detection device is that the transmitter and the receiver are arranged on different sides of the crossing, so that the cable wiring must be laid on both sides of the crossing. However, the cable length is increased, and the number of cables is increased.

[0005] Another problem of the conventional optical detection device is that the optical axis adjustment operation is troublesome. That is, in order for this type of optical detection device to operate normally, it is necessary to make adjustments so that both the optical axis of the light transmitter and the optical axis of the light receiver coincide. However, since the transmitter and receiver are located on different sides of the railroad crossing, it is not possible to perform optical axis adjustment work on only one side of the railroad crossing. It is necessary to adjust the optical axis of the light transmitter and the optical axis of the light receiver by reciprocating the optical axis.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an optical sensing device which can be installed with a small number of cables.

Another object of the present invention is to provide an optical detection device that can easily adjust the optical axis.

Yet another object of the present invention is to provide an optical sensing device having a large sensing area.

[0009]

In order to solve the above-mentioned problems, an optical detection device according to the present invention includes a detection area, a detection unit, and a signal processing unit. The detection area forms an area for a detected object.

[0010] The detection section includes a light transmitter, a light receiver, and a reflector. The light transmitter and the light receiver are arranged on one side of the detection area. The reflector is disposed on the other side of the detection area, a plurality of reflectors are provided for a set of the light transmitter and the light receiver, each of the reflectors,
They are spaced apart from each other.

[0011] The detection unit may be configured to detect an optical path through which the light transmitted from the light transmitter is sequentially incident on the light receiver through one of the detection area, the reflector, and the detection area. Is configured.

The signal processing unit detects the presence or absence of the detected object in the detection area by decoding a signal supplied from the light receiver.

In the above-described optical detecting device according to the present invention, an operation when there is no detected object in the detection area will be described first. In this case, the optical path is not blocked by the detected object. Therefore, the optical path in which the light transmitted from the light transmitter sequentially enters one of the detection area, the reflector, and the detection area and enters the light receiver is maintained.
For this reason, a certain amount of light corresponding to the optical path is received by the light receiver, and the signal processing unit detects “no detected object” by decoding the signal supplied from the light receiver.

Next, the operation when the detected object enters the detection area will be described. In this case, since the optical path is blocked by the detected object, the light transmitted from the light transmitter enters the light receiver via one of the detection area, the reflector, and the detection area in order. No light path is configured. At this time, the signal processing unit detects "there is an object to be detected".

The light transmitted from the light transmitter is transmitted to a detection area,
The optical path incident on the light receiver via one of the reflectors and the detection area sequentially and the optical path when the optical path is interrupted by the object to be detected are different in the optical path length and the amount of received light. Therefore, the signal processing device detects the presence or absence of the detected object from the optical path length difference or the received light amount difference or a combination of both.

Here, in the optical detection device according to the present invention, the light transmitter and the light receiver are arranged on the same side of the detection area. Therefore, the cable wiring may be laid only on one side of the detection area. Further, it becomes possible to use a multi-core cable and share the cable wiring between the transmitter and the receiver.
Therefore, the cable length can be shortened and the number of cables can be reduced.

Further, since the light transmitter and the light receiver are arranged on the same side of the detection area, the optical axis adjustment of the light transmitter and the light axis adjustment of the light receiver can be performed on the same side of the detection area. it can. Therefore, it is possible to obtain an optical detection device whose optical axis can be easily adjusted.

When the transmitter and the receiver are integrated,
The optical axis adjustment of the light transmitter and the optical axis adjustment of the light receiver can be performed at the same position. Therefore, it is possible to obtain an optical detection device with easier optical axis adjustment.

Further, the light transmitter and the light receiver are arranged on one side of the detection area. The reflector is arranged on the other side of the detection area, and a plurality of reflectors are provided for one set of the light transmitter and the light receiver, and each of the reflectors is arranged at a distance from each other. Therefore, by changing the directivity of a set of light transmitter and light receiver and scanning a plurality of reflectors, the detection area can be enlarged and the object to be detected can be detected in a wide range.

It is preferable that the light transmitter and the light receiver have a function of sequentially scanning the reflector. As the scanning function,
In particular, a rotation scanning function is suitable. When a scanning function is provided, it is desirable that the light transmitter and the light receiver be integrated. When the light transmitter and the light receiver are integrated, both can be simultaneously rotated to perform rotational scanning.

Other objects, configurations and advantages of the present invention will be described in more detail with reference to the accompanying drawings. The drawings are merely examples.

[0022]

FIG. 1 is a diagram showing the configuration of an embodiment of an optical detection device according to the present invention. This embodiment shows an example in which the optical detection device according to the present invention is applied to level crossing obstacle detection. However, the present invention is not limited to railroad crossing obstacle detection, and can be applied to other uses, for example, train detection at a branch portion in a station yard or the like. Further, the present invention can be applied to train position detection in a station yard, a garage, and the like.

As shown in FIG. 1, the optical detection device according to the present invention comprises detection areas 31 and 32, detection sections 1 and 2,
And a signal processing unit 4. In the embodiment, the detection units 1 and 2
The detection units 1 and 2 are provided corresponding to the detection areas 31 and 32, respectively, and detect the detected objects in the detection areas 31 and 32, respectively. In the embodiment, two detectors 1 and 2 are provided, but one may be provided. Detection area 31, 3
2 constitutes an area for the detected object. In the embodiment, the detection areas 31 and 32 are set so as to cover the entire railroad crossing 71 with both. Railroad crossing 71
Crosses the track 72 on which the train runs.

The detector 1 includes a light transmitter 11 and a light receiver 12
And reflectors 131, 132, and 133. Transmitter 1
1 and the light receiver 12 are arranged on one side of the detection area 31. The reflectors 131, 132, and 133 are provided in the detection area 3
1 and a set of a light transmitter 11 and a light receiver 1
A plurality is provided for two. Each of the reflectors 131 to 133 is arranged at a distance from one side where the light transmitter 11 and the light receiver 12 are arranged, in a direction intersecting the direction in which the other side is seen.

The detector 1 transmits the light transmitted from the light transmitter 11 to the light receiver 12 via the detection area 31, one of the reflectors 131, 132, 133 and the detection area 31 in order. The incident optical paths 141, 142, and 143 are configured. The optical paths 141, 142, and 143 are optical paths through which light passes through the reflectors 131, 132, and 133, respectively. As the light, infrared light, semiconductor laser light, or the like is used.

The detector 2 also includes a light transmitter 21 and a light receiver 22
And reflectors 231, 232, and 233. Transmitter 2
1 and the light receiver 22 are arranged on one side of the detection area 32. The reflectors 231, 232, and 233 are connected to the detection area 3
2 and one set of the light transmitter 21 and the light receiver 2
A plurality is provided for two. . Each of the reflectors 231 to 233 is arranged at an interval from one side where the light transmitter 21 and the light receiver 22 are arranged in a direction intersecting the direction in which the other side is seen.

The detector 1 sends the light transmitted from the light transmitter 21 to the light receiver 22 via the detection area 32, one of the reflectors 231, 232, and 233 and the detection area 32 sequentially. The incident optical paths 241, 242, and 243 are configured. The optical paths 241, 242, and 243 are optical paths through which light passes through the reflectors 231, 232, and 233, respectively.

The signal processing section 4 decodes the signal supplied from the photodetector 12 or 22 so that the detection area 3
The presence or absence of the detected object in 1 or 32 is detected.

Next, the operation of the optical detection device according to the present invention will be described. An operation of detecting an object to be detected in the detection area 31 by the detection unit 1;
The operation of detecting the object to be detected is the same,
Hereinafter, for simplicity, only the operation of the detection unit 1 will be described, and the description of the operation of the detection unit 2 will be omitted.

First, the operation when there is no detected object in the detection area 31 will be described. In this case, the optical paths 141, 1
Neither of 42 nor 143 is blocked by the detected object. Accordingly, the optical path 141 in which the light transmitted from the light transmitter 11 sequentially enters the light receiver 12 via the detection area 31, the reflector 131, and the detection area 31 is maintained, and similarly, the optical paths 142 and 143 are provided. Is also maintained. For this reason, constant light corresponding to the optical paths 141, 142, and 143 is received by the light receiver 12. The signal processing unit 4 detects that there is no detected object in the detection area 31 by decoding the signal supplied from the light receiver 12.

Next, the operation when the detected object 8 enters the detection area 31 will be described. In this case, the optical path 14
At least one of 1, 142, and 143 is blocked by the detected object 8. For example, assuming that the optical path 141 is blocked, the light transmitted from the light transmitter 11 is transmitted to the detection area 31,
An optical path 141 that is sequentially incident on the light receiver 12 via the reflector 131 and the detection area 31 is not formed. At this time, the signal processing unit 4 detects that “the detected object is present in the detection area 31”.

The light transmitted from the light transmitter 11 is cut off by the light path 141 which enters the light receiver 12 through the detection area 31, the reflector 131, and the detection area 31 sequentially, and the object to be detected. The light path length and the amount of received light are different from those at the time. The same applies to the optical paths 142 and 143.
Therefore, the signal processing unit 4 detects the presence or absence of the detected object in the detection area 31 from the difference in the optical path length or the difference in the amount of received light or a combination of both.

Here, in the detection unit 1, the light transmitter 11 and the light receiver 12 are arranged on the same side of the detection area 31. For this reason, the cable wiring 51 may be laid only on one side of the detection area 31. Further, using a multi-core cable,
1 and the light receiver 12 can share the cable wiring 51. Therefore, the cable length can be shortened and the number of cables can be reduced.

Further, since the light transmitter 11 and the light receiver 12 are arranged on the same side of the detection area 31, the adjustment of the optical axis of the light transmitter 11 and the adjustment of the optical axis of the light receiver 12 are performed in the same manner. Can be performed on the side. Therefore, it is possible to obtain an optical detection device whose optical axis can be easily adjusted.

The light transmitter 11 and the light receiver 12 may be integrated. In the case of such a configuration, adjustment of the optical axis of the light transmitter 11 and
The optical axis adjustment of the light receiver 12 can be executed at the same position. Therefore, it is possible to obtain an optical detection device with easier optical axis adjustment.

The detector 1 is configured so that the light transmitted from the light transmitter 11 is reflected by any one of the reflectors 131, 132, and 133 and is incident on the light receiver 113. The optical paths 141, 142, 143 are respectively
It is bent at 1, 132, 133. Therefore, it becomes possible to arrange the light transmitter 11 and the light receiver 12 on the same side of the detection area 31.

Further, the light transmitter 11 and the light receiver 12 are arranged on one side of the detection area 31. Reflectors 131, 13
2 and 133 are arranged on the other side of the detection area 31,
A plurality of transmitters 11 and a plurality of light receivers 12 are provided. Each of the reflectors 131, 132, and 133 is spaced apart from each other. Therefore, one set of light transmitters 11
And the direction of the light receiver 12 is changed, and a plurality of reflectors 13
By scanning 1, 132 and 133, the detection area 31 can be enlarged, and the object to be detected can be detected in a wide range.

In the detecting section 1, although only one light transmitter and one light receiver are provided, one set of the light transmitter 11 and the light receiver 12 includes a plurality of reflectors 131, 1
32, 133, the detection area 31
Can be detected, and the object to be detected can be detected in a wide range. Thus, it is sufficient to provide only one light transmitter and one light receiver while covering a wide detection area.

The light transmitter 11 and the light receiver 12 include a reflector 13
It is preferable to have a function of sequentially scanning 1, 132, and 133. For example, according to the time chart shown in FIG.
32 and 133 are scanned. As the scanning function, a rotary scanning function is particularly suitable.

When a scanning function is provided, it is desirable that the light transmitter 11 and the light receiver 12 are integrated. When the light transmitter 11 and the light receiver 12 are integrated, both can be simultaneously rotated to perform rotational scanning.

Since the detecting section 2 has the same configuration, arrangement and the like as the detecting section 1, the same operation and effect as the detecting section 1 can be obtained.

Incidentally, as described above, the signal processing unit 4
Detects the presence or absence of the detected object in the detection area 31 from the difference in the optical path length or the difference in the amount of received light or a combination of both. The detection method focusing on the optical path length difference includes phase difference detection. Next, the detection operation based on the phase difference will be described with reference to FIGS.
This will be described with reference to FIG. When the phase difference is detected, a pulse modulation signal such as infrared light or semiconductor laser light is used as the optical signal.

First, as shown in FIG.
When there is no object to be detected, the optical path 141 is not blocked by the object to be detected, and the optical path length of light along the optical path 141 is kept constant. Therefore, as shown in FIGS. 3A and 3B, the phase difference D between the light transmission and the light reception shows a certain constant value D0. The same applies to the optical paths 142 and 143. Therefore, the signal processing unit 4 detects that "there is no object to be detected in the detection area 31".

Next, the detected object 8 enters the detection area 31, for example, the optical path 141 may be blocked by the detected object 8, and the light from the optical path 141 may not enter the light receiver 113. FIG. 4 shows such a state.
In the state shown in FIG. 4, the signal processing unit 4
1, there is an object to be detected ". Optical path 142, 1
The same applies when 43 is blocked.

The detected object 8 enters the detection area 31 and, for example, the light sent from the light transmitter 11 is transmitted by the detected object 8 even though the optical path 141 is blocked by the detected object 8. The light may be reflected and incident on the light receiver 12. FIG. 5 is a diagram showing the above case. However, in this case, since the light does not travel along the optical path 141 and the optical path length of the light is different from the state without the detected object, the position is not changed as shown in FIGS. The phase difference D indicates a value D1 different from the value D0 in a state where there is no detected object. Therefore, the signal processing unit 4 can detect that “the detected object is present in the detection area 31”. Optical path 14
The same applies to the case where light is incident on the light receiver 12 despite the fact that the light beams 2 and 143 are blocked.

An optical disturbance may occur in the environment of the detection unit 1. For example, the brightness of the light environment changes according to day or night. However, as described above, the signal processing unit 4
The presence or absence of the detected object in the detection area 31 is determined by decoding the phase difference between the light transmission and the light reception. For this reason, even if optical disturbance occurs in the environment, the signal processing unit 4 can reliably detect the presence or absence of the detected object in the detection area 31 without being affected by the optical disturbance.

Consider a case where a failure occurs such that the phase difference D between light transmission and light reception in the optical path 141 deviates from the original value D0. At this time, since the phase difference D indicates a value different from the value D0 in a state where there is no detected object, the signal processing unit 4 determines that “the detected object is present in the detection area 31”.
Is detected. This means that the optical detection device of the phase difference detection type operates on the safe side.

As another embodiment, the signal processing unit 4 decodes the amount of light received by the light receiver 12 in addition to the phase difference D between the time when light is transmitted and the time when light is received, so that The presence or absence of the detected object can also be detected. When the signal processing unit 4 is configured in this manner, the signal processing unit 4 decodes two different elements, that is, the phase difference of light and the amount of received light, so that the presence or absence of the detected object can be detected more reliably.

[0049]

As described above, according to the present invention, the following effects can be obtained. (A) An optical detection device that can be installed with a small number of cables can be provided. (B) It is possible to provide an optical detection device that can easily adjust the optical axis. (C) To provide an optical detection device having a wide detection area.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration in an embodiment of an optical detection device according to the present invention.

FIG. 2 is a time chart showing a function in which a light transmitter and a light receiver scan a reflector.

FIG. 3 is a diagram showing a comparison between values of a phase difference between light transmission and light reception.

FIG. 4 is a diagram illustrating a case where a detected object enters a detection area and an optical path is blocked by the detected object;

FIG. 5 is a diagram illustrating a case where light emitted from a light transmitter is reflected by a detected object and enters a light receiver, even though the detected object has entered a detection area.

[Explanation of symbols]

 REFERENCE SIGNS LIST 31 detection area 32 detection area 1 detector 11 light transmitter 12 light receiver 131, 132, 133 reflector 141, 142, 143 optical path 2 detector 21 light transmitter 22 light receiver 231, 232, 233 reflector 241, 242 243 optical path 4 signal processing unit

Claims (6)

[Claims] 1. An optical detection device including a detection area, a detection unit, and a signal processing unit, wherein the detection area constitutes an area for an object to be detected, A light transmitter, a light receiver, and a reflector, wherein the light transmitter and the light receiver are arranged on one side of the detection area, and the reflector is another side of the detection area. Placed in the 1
A plurality of sets are provided for the transmitter and the receiver.
Each of the reflectors is arranged at an interval from each other, the detection unit, the light transmitted from the light transmitter, the detection area, any one of the reflector and the detection area Constitutes an optical path that is sequentially incident on the light receiver, the signal processing unit decodes a signal supplied from the light receiver, thereby detecting the object to be detected in the detection area. Optical detection device that detects the presence or absence. 2. The optical detection device according to claim 1, wherein the light transmitter and the light receiver have a function of scanning the reflector. 3. The optical detection device according to claim 2, wherein the light transmitter and the light receiver have a rotation scanning function. 4. The optical detection device according to claim 1, wherein the light transmitter and the light receiver are integrated. 5. The optical detecting device according to claim 1, wherein the detecting device detects an obstacle to a train at a railroad crossing. 6. The optical detecting device according to claim 1, wherein the signal processing unit transmits light when the light transmitter transmits light, and An optical detection device for detecting the presence or absence of an object to be detected in the detection area by decoding a phase difference from when light is received by a light receiver.