JP3866604B2 - Optical curtain type safety sensor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a light curtain type safety sensor for detecting an intrusion into a dangerous area and stopping a machine or the like disposed in the dangerous area, for example.
[0002]
[Prior art]
For example, since it is dangerous if an operator inadvertently approaches an area where a machine that operates in a factory is installed, an intrusion into the dangerous area where the machine is installed is detected and placed in the dangerous area. There is a light curtain type safety sensor for stopping the machine.
[0003]
In this type of safety sensor, a plurality of sets of light projecting / receiving units A and B are arranged at a necessary interval with their optical axes aligned as shown in FIG. 4, and synchronization is sequentially performed between the light projecting / receiving units A and B. The scanning is electrically performed by switching by the light projection switching unit C and the light reception switching unit D. In this safety sensor, when an operator or the like enters the detection area L between the light projecting / receiving units A and B, light traveling from the light projectors 1a to Na to the light receivers 1b to Nb is blocked by the intruder. It is possible to detect the intrusion into the dangerous area by the light shielding by the intruder, and the machine is automatically stopped based on the detection signal.
[0004]
[Problems to be solved by the invention]
By the way, the above-described safety sensor has the following problems because it has a structure for detecting the presence or absence of light shielding between the light projecting and receiving units A and B.
[0005]
For on-site workers, working efficiency is poor if the machine is stopped intentionally for maintenance or parts loading. In such a case, if the work can be done without the safety sensor being activated, the working efficiency will be improved. be able to. Therefore, as shown in FIG. 5, there may be provided a passage m through which the position of the light projecting unit A or the light receiving unit B is intentionally shifted to narrow the interval between the light projecting / receiving units A and B and can enter the dangerous area X. Since there is a risk that accidents occur frequently due to such invalidation of the safety sensor by the worker, there is a demand that the worker on site cannot easily remodel the safety sensor.
[0006]
In addition, there is a restriction that the spread of light from the light projecting unit A is not more than 2 degrees in order to prevent light from wrapping around due to reflection of peripheral devices. Therefore, the light projecting unit A that emits directional light must be used, and as a result, it is difficult to align the optical axes of the light projecting and receiving units A and B. Also, even when the installation position of the device is high or when the interval between the light emitting / receiving units A and B is increased, it is very difficult to align the optical axes of the light emitting / receiving units A and B, and it takes a lot of time for installation adjustment and maintenance. There was also a problem.
[0007]
Therefore, the present invention has been proposed in view of the above problems, and the purpose of the present invention is that an on-site worker cannot be easily remodeled, and the optical axis alignment of the light projecting / receiving unit is easy and can be installed. The object is to provide a light curtain type safety sensor that takes less time for adjustment and maintenance.
[0008]
[Means for Solving the Problems]
As technical means for achieving the above object, the present invention has the following features.
[0009]
According to the first aspect of the present invention, a light projecting / receiving unit comprising a light projector and a light receiver and a reflecting plate for reflecting the light emitted from the light projector and making it incident on the light receiver are arranged facing each other at a predetermined interval, By monitoring the distance between the light emitting / receiving unit and the reflecting plate, the presence or absence of intrusion into the detection area set between the light emitting / receiving unit and the reflecting plate is monitored. It is characterized by that.
[0010]
The invention according to claim 2 is characterized in that a plurality of sets of light projecting / receiving devices are arranged in parallel on a straight line, and light projecting / receiving between the light projecting / receiving device and the reflecting plate is electrically scanned by the light projecting / receiving device.
[0011]
According to a third aspect of the present invention, a pair of projector / receiver and a reflector are arranged opposite to each other, and the projector / receiver / reflector is mechanically scanned by a mirror arranged in front of the projector / receiver. It is characterized by.
[0012]
According to a fourth aspect of the present invention, a deflector plate is disposed in front of the projector, a deflector plate is disposed in front of the light receiver so as to be orthogonal to a deflection direction of the deflector of the projector, and the reflector plate is disposed from the projector. The retroreflector is provided with a function of deflecting the deflection direction of the emitted light by 90 °.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows a first embodiment of a light curtain type safety sensor according to the present invention.
[0014]
In the safety sensor of this embodiment, the light projecting / receiving units E accommodating a plurality of sets of light projecting / receiving devices 1a, 1b to Na, Nb are arranged in a straight line and reflected with a predetermined interval from the light projecting / receiving unit E. The plates M are arranged opposite to each other, and are electrically scanned by switching between the light projecting switch C and the light receiving switch D while sequentially synchronizing the light projecting / receiving units E. In the light projecting / receiving unit E, the light emitted from the light projectors 1a to Na is reflected by the reflector M, and the reflected light is incident on the light receivers 1b to Nb. The distance between the light projecting / receiving unit E and the reflecting plate M is measured by monitoring the phase difference between the light emitted from the light projecting devices 1a to Na and the light incident on the light receiving devices 1b to Nb reflected by the reflecting plate M. Like to do. In this safety sensor, it is only necessary to set the arrangement pitch of the light projectors / receivers 1a, 1b to Na, Nb, so that it is not necessary to align the optical axes of the light projectors 1a to Na and the light receivers 1b to Nb.
[0015]
In this safety sensor, when an operator or the like enters between the light projecting / receiving unit E and the reflecting plate M, the distance from the light projecting / receiving unit E to the reflecting plate M can be changed to detect the intrusion into the dangerous area. The machine is automatically stopped based on the detection signal. Further, even if the position of the light projecting / receiving unit E or the reflecting plate M is intentionally shifted to reduce the distance between the light projecting / receiving unit E and the reflecting plate M and provide a path that can enter the dangerous area, the light projecting / receiving unit E to the reflecting plate M The distance to the vehicle will change and can be detected, so it cannot be easily modified by field workers.
[0016]
FIG. 2 shows a second embodiment of the present invention. In the safety sensor of this embodiment, a deflection plate F is disposed in front of the projectors 1a to Na, and the deflection direction is perpendicular to the deflection plates F of the projectors 1a to Na in front of the light receivers 1b to Nb. A deflecting plate G is arranged. On the other hand, the retroreflective plate M ′ is disposed opposite to the light projecting / receiving unit E at a predetermined interval. The return reflection plate M ′ has a function of reflecting incident light with its deflection direction bent by 90 °.
[0017]
In this safety sensor, when an operator or the like enters between the light projecting / receiving unit E and the return reflection plate M ′, the distance from the light projecting / receiving unit E to the return reflection plate M ′ changes to detect entry into the dangerous area. The machine is automatically stopped based on this detection signal. At this time, since the light emitted from the projectors 1a to Na through the deflecting plate F is deflected by 90 ° by the return reflection plate M ′, the reflected light deflected by 90 ° is received through the deflecting plate G. Are incident on and received by the devices 1b to Nb. On the other hand, if the light is reflected by an object other than the regressive reflection plate M ′, the light from the projectors 1a to Na is incident on the deflection plate G without being deflected and is not received by the light receivers 1b to Nb. Even if the position of the light projecting / receiving unit E or the return reflection plate M ′ is intentionally shifted to narrow the distance between the light projecting / receiving unit E and the return reflection plate M ′ to provide a path that can enter the dangerous area, the light projecting / receiving unit E Since the distance from the reflex reflector M ′ to the reflex reflector M ′ can be detected and detected, it cannot be easily remodeled by a field worker.
[0018]
FIG. 3 shows a third embodiment of the present invention. The safety sensor of this embodiment is different from the above-described embodiment in which a plurality of sets of light emitters / receivers are arranged side by side, with respect to a set of light emitters / receivers 1a and 1b (first light emitter / receiver unit E ₁ ). The first reflector M ₁ is arranged opposite to each other with a predetermined distance, and in the opposite direction, a predetermined amount is set with respect to the other set of light emitters / receivers 2a, 2b (second light emitter / receiver unit E ₂ ). a second reflector M ₂ opposite spaced. In each of the light projecting / receiving units E ₁ and E ₂ , the detection area L is set not by electrical scanning but by mechanical scanning by using a mirror (not shown).
[0019]
Also in the safety sensor of this embodiment, when such worker from entering between the light emitting and receiving unit E _1, E ₂ and the reflector M _1, M _2, reflector M ₁ from the light emitting and receiving unit E _1, E _2, M ₂ The intrusion into the dangerous area can be detected by changing the distance to the machine, and the machine is automatically stopped based on the detection signal. Further, the positions of the light projecting / receiving units E ₁ , E ₂ or the reflecting plates M ₁ , M ₂ are deliberately shifted to narrow the distance between the light projecting / receiving units E ₁ , E ₂ and the reflecting plates M ₁ , M ₂ to enter the dangerous area. Even if an attempt is made to provide a path that can be used, the distance from the light projecting / receiving units E ₁ and E ₂ to the reflectors M ₁ and M ₂ will change and can be detected. Can not do it.
[0020]
Although not shown, in the configuration of the third embodiment as well, in the same way as in the second embodiment, a deflector plate F is disposed in front of the projectors 1a and 2a and in front of the light receivers 1b and 2b. The deflecting plate G is arranged so that the deflecting direction is perpendicular to the deflecting plate F of the projectors 1a and 2a. On the other hand, the return reflection plate M ′ may be disposed opposite to the light projecting / receiving units E ₁ and E _{2 at} a predetermined interval.
[0021]
【The invention's effect】
According to the present invention, even if an attempt is made to intentionally shift the position of the light projecting / receiving unit or the reflecting plate to narrow the distance between the light projecting / receiving unit and the reflecting plate to enter the dangerous area, the light emitting / receiving unit to the reflecting plate can be provided. Because the distance will change and can be detected, it cannot be easily modified by field workers, the light axis of the light emitting / receiving unit is easy to adjust, and light that does not take time for installation adjustment and maintenance A curtain-type safety sensor can be provided.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing a first embodiment of a light curtain type safety sensor according to the present invention.
FIG. 2 is a schematic configuration diagram showing a second embodiment of the light curtain type safety sensor according to the present invention.
FIG. 3 is a schematic configuration diagram showing a third embodiment of the light curtain type safety sensor according to the present invention.
FIG. 4 is a schematic configuration diagram showing a conventional example of a light curtain type safety sensor.
FIG. 5 is a schematic configuration diagram for explaining a problem in a conventional light curtain type safety sensor.
[Explanation of symbols]
1a to Na Emitter 1b to Nb Receiver E Emitter / Receiver Unit M Reflector L Detection Area

Claims (4)

A light projecting / receiving unit composed of a light projector and a light receiver and a reflecting plate that reflects the light emitted from the light projector and enters the light receiving device are arranged opposite to each other with a predetermined distance therebetween, and the light projecting unit between the light projecting / receiving unit and the light reflecting plate is disposed. Light curtain characterized by monitoring the presence or absence of intrusion into the detection area set between the light projecting / receiving unit and the reflecting plate by scanning the received light and measuring the separation distance from the light projecting / receiving unit to the reflecting plate Safety sensor. The light curtain type according to claim 1, wherein a plurality of sets of light emitters / receivers are arranged in parallel on a straight line, and light projection / reception between the light emitter / receiver and the reflector is electrically scanned by a light emitter / receiver switch. Safety sensor. 2. A pair of light emitters / receivers and a reflector are arranged opposite to each other, and light projection / reception between the light emitter / receiver and the reflector is mechanically scanned by a mirror disposed in front of the light emitter / receiver. Light curtain type safety sensor as described in 1. A deflector plate is arranged in front of the projector, and a deflector plate is arranged in front of the light receiver so as to be orthogonal to the deflecting direction of the deflector of the projector, and the deflecting direction of the outgoing light from the projector is changed. The light curtain type safety sensor according to any one of claims 1 to 3, wherein the retroreflective plate has a function of deflecting by 90 °.

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