JPH07122989A - Multi-optical axis photoelectric switch - Google Patents

Abstract

PURPOSE:To quickly and exactly detect a light shielding state even when intensive diffused external light due to welding spatter light, etc., is made incident. CONSTITUTION:A projector 1 and a light receiver 2 are connected by a synchronizing line 3 for delivering and receiving a synchronizing reference signal and a projecting light control signal. Each LFED 8a to 8d of the projector 1 successively outputs pulse light by the synchronizing signal according to the synchronizing reference signal. The corresponded photodiodes 16a to 16d of the light receiver 2 receives pulse light by a synchronized timing. A light reception control circuit 11 outputs a projecting light control signal when the data imparting a light reception state is not inputted, makes the LED and the photodiode of the same optical axis perform projecting and receiving light operations again and inputs a light reception signal. Thus, the fact that the state is not the light shielding state by a light shielding object can be quickly detected because the imparting of continuous light shielding states is extremely rare when the light reception signal where temporary diffused external light such as spatter light, etc., is made incident and the light shielding state is imparted is made.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has a plurality of optical axes formed by a pair of a light emitting element and a light receiving element, and when any one of these optical axes is shielded, it is judged as a light shielding state. The present invention relates to an optical axis photoelectric switch.

[0002]

2. Description of the Related Art Conventionally, a multi-optical axis photoelectric switch has been used as a safety device of a press machine or an intrusion warning device in a dangerous area. In this device, a light projector having a plurality of light emitting elements and a light receiver having a plurality of light receiving elements corresponding to each of the plurality of light emitting elements are arranged so as to face each other, and a detection area is set between them. , Is configured to sequentially emit light from a plurality of light projecting elements and to perform a light receiving operation by a light receiving element corresponding to each light projecting element in a state synchronized with the light projecting timing, and a light shielding object exists in the detection area. In some cases, the light receiving signal from the light receiving element disappears, and it is possible to determine the light blocking state of the optical axis based on this and output the object detection signal.

Then, based on the object detection signal, the press device is stopped or an alarm is issued by detecting an intrusion of a person into a dangerous area in a factory to prevent an accident. It was done.

[0004]

In the above-described multi-optical axis photoelectric switch, when strong disturbance light such as welding sputter light is incident on the light receiving element, the original signal light from the light emitting element changes. It may be buried in the ambient light and the light reception signal may not be obtained. This is, for example, when pulsed light from the corresponding light projecting element enters at the timing when strong sputtered light enters the light receiving element of a certain optical axis and the received light signal largely changes from positive to negative. This is because the amplitude of the received light signal corresponding to the light becomes smaller than the amplitude when the sputtered light changes to a negative value, and thus does not reach the level for detecting the light receiving state.

If such a situation occurs, there is a possibility that the light-shielding state is erroneously determined because the light-receiving element cannot obtain a light-receiving signal even though the light-shielding object does not exist in the detection area. Therefore, as a result, there is a problem that the device is inadvertently stopped, an alarm is issued, or a malfunction occurs.

Therefore, in order to eliminate such a problem, for example, as disclosed in Japanese Utility Model Laid-Open No. 2-108441, the light blocking state is determined based on a plurality of light receiving signals, so that the light blocking state is surely achieved. Is output and an object detection signal is output.

That is, in this device, the detection signal from the light receiving element is stored for at least one scanning or more, and the determination means sequentially compares the stored content of the light receiving signal from the light receiving element with each optical axis. However, at that time, the light-shielding state is determined on the condition that one of the light-receiving element groups repeats the light-shielding detection a predetermined number of times. As a result, while preventing erroneous detection due to transient ambient light, the light-shielding state is determined by sequentially comparing each optical axis in the scanning state, and the corresponding light is emitted each time scanning is completed. The detection response time can be shortened as compared with the case where it is determined whether or not the light receiving signal in which the shaft is in the light-shielded state is detected a predetermined number of times.

However, even with such a configuration, the light blocking state is determined for each optical axis because one scanning is completed at least when the light blocking state of the optical axis is detected and the light receiving of the same optical axis is performed again. Since the light-shielding state is detected by the element, the larger the number of set scans for determining the detection of the light-shielding state is, the more scanning is completed from the time when the light-shielding state is first detected, and the light-shielding state is changed. Since it takes time to detect, increasing the number of scans for light-blocking determination to reliably detect results in a longer detection response time, and when a quick detection operation is required. There is a problem that becomes inappropriate.

The present invention has been made in view of the above circumstances, and an object thereof is to prevent an erroneous detection due to ambient light such as sputtered light as much as possible, and at the time when the optical axis is actually shielded. Therefore, it is possible to quickly detect the light blocking state of the optical axis without waiting for a predetermined number of scans to be performed, and thus to shorten the detection response time regardless of the number of optical axes. An optical axis photoelectric switch is provided.

[0010]

A multi-optical axis photoelectric switch of the present invention is provided with a light projecting section having a plurality of light projecting elements and a one-to-one opposition to each light projecting element of the light projecting section. The light receiving section having a plurality of light receiving elements and each light projecting element of the light projecting section are sequentially caused to perform a light projecting operation at a predetermined light projecting timing, and when a light projecting control signal is given, the light projecting operation is carried out at that time. The light emitting control means for controlling the light emitting element to continuously perform the light emitting operation a plurality of times, and the light receiving signals of the respective light receiving elements of the light receiving section are effective in synchronization with the light emitting timing of the corresponding light emitting element. Light-receiving control means that outputs a light-emission control signal when a light-receiving signal indicating a light-shielded state is input, and controls the light-receiving element that has received light at that time to continuously perform light-receiving operation, Output from the light receiving control means The signal transmitting means for transmitting the light control signal to the light projecting control means and the light receiving control means judge the light blocking state when the light receiving signal indicating the light blocking state is output from the same light receiving element a plurality of times. It is characterized in that it is provided with a determining means for outputting an object detection signal.

[0011]

According to the multi-optical axis photoelectric switch of the present invention, the light projecting control means causes each light projecting element of the light projecting section to sequentially carry out the light projecting operation at a predetermined light projecting timing, and the light receiving control means receives the light received. The light receiving signals of the respective light receiving elements of the unit are activated and input in a state of being synchronized with the corresponding light emitting elements. Then, the light receiving control means, when the light receiving signal exhibiting the light blocking state is inputted from any one of the light receiving elements, gives the light emitting control signal to the light emitting control means via the signal transmitting means, and continuously transmits to the light receiving element a plurality of times. Then, the light projecting control means causes the light projecting element, which has performed the light projecting operation at that time, to carry out the light projecting operation a plurality of times in response to the applied light projecting control signal. Like

Accordingly, when the optical axis corresponding to the light receiving element that outputs the light receiving signal exhibiting the light shielding state is actually shielded by the object, the light receiving element outputs the light receiving signal exhibiting the light shielding state again. However, if a strong disturbance light such as welding spattering light is incident on the light receiving element and the light emitting signal from the light emitting element is buried and the light receiving signal indicating the light blocking state is output, the light receiving element outputs It is expected that a light receiving signal indicating the light receiving state will be output.

Then, when the light receiving signal exhibiting the light blocking state is output from the same light receiving element a plurality of times, the determining means judges that the light receiving state is in the light blocking state and outputs the object detection signal. As described above, when the received light signal that is in the light-shielded state due to the ambient light is output, it is not determined that the ambient light is the light-shielded state based on the fact that the ambient light is transient. It becomes possible to detect the light-shielded state quickly without waiting until one scan is completed while preventing.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1 showing an electrical configuration, a light emitter 1 and a light receiver 2 are arranged so as to face each other with a detection area in between, and a synchronization line 3 which also functions as a signal transmission means is connected between them. Has been done.

In the projector 1, the projection control circuit 4 as a projection control means is composed of a microcomputer or the like, and a program for projection control is stored in advance to perform a projection operation. The light emitting signal is output based on a frequency signal generated by an internal oscillation function. In this case, the light emitting signal generates a synchronization reference signal indicating the beginning of one scanning to synchronize with the light receiver 2 side described later, and a synchronization generated at a predetermined timing based on the synchronization reference signal. It is designed to be output according to the signal.

The shift register 5 is adapted to be supplied with a light projecting signal from the light projecting control circuit 4, and each time the light projecting signal is supplied from the reset state, its four output terminals Q are provided.
Signals of "H" level are sequentially output from 1, Q2, Q3, and Q4 to shift the output state.

Output terminals Q1 to Q1 of the shift register 5
Q4 is connected to one input terminal of each of the AND circuits 6a, 6b, 6c, 6d. AND circuits 6a-6
The other input terminal of d is connected to the output terminal A of the light projection control circuit 4. Each output terminal of the AND circuits 6a to 6d is a plurality of light emitting elements, for example, four LEDs 8a, 8b, 8 via the drive circuits 7a, 7b, 7c, 7d.
It is connected to c and 8d.

The output terminal B of the projection control circuit 4 is an output circuit 9
Is connected to the synchronizing line 3 via the input terminal C, and the input terminal C is connected to the synchronizing line 3 via the input circuit 10. The light emission control circuit 4 outputs the above-mentioned synchronization reference signal via the output circuit 9, and this synchronization reference signal is transmitted to the light receiver 2 side via the synchronization line 3. .
A signal transmitted from the light receiver 2 side via the synchronizing line 3 is applied to the input terminal C of the light projecting control circuit 4 via the input circuit 10.

Next, in the photodetector 2, the photodetection control circuit 1 having the functions of the photodetection control means and the determination means.
Reference numeral 1 denotes a microcomputer or the like, which stores in advance a light receiving determination control program for light receiving control and light blocking determination. Shift register 1
The light receiving control circuit 11 is provided with a shift signal 2 which is synchronized with the above-mentioned light emitting signal, and sequentially outputs "H" level signals from its four output terminals P1, P2, P3 and P4. Then, the output state is shifted.

Each output terminal P1 of this shift register 12
To P4 are analog switches 13a, 13b, 1 respectively.
It is connected to the gate terminals of 3c and 13d. The output terminal of the comparator 14 is connected to the input terminal D of the light receiving control circuit 11, and the input terminal of the comparator 14 is connected to the output terminal sides of the analog switches 13a to 13d. The input terminals of the analog switches 13a to 13d are connected to the light receiving circuits 15a, 15b, 15c and 15 respectively.
For example, four photodiodes 16a, 16b, 16c, 16d, which are a plurality of light receiving elements, are connected via d.

In this case, the photodiodes 16a to 16a
d is arranged at a position facing each of the LEDs 8a to 8d of the projector 1 with a detection area sandwiched therebetween to form four optical axes, and when pulsed light is incident from the corresponding LEDs 8a to 8d, this is photoelectrically converted. The light receiving signal is sent to the light receiving circuit 1
5a to 15d, and a light receiving signal corresponding to the presence or absence of an object existing in the detection area is output.

The analog switches 13a to 13d are also provided.
Is enabled by the shift register 12 in a state of being synchronized with the light emitting signal by the synchronization signal output from the light receiving control circuit 11, and the light receiving circuits 15a to 15d.
The received light signal amplified by is output to the comparator 14. When the level of the received light receiving signal is equal to or higher than the reference level for detecting the light receiving state, the comparator 14 outputs an “H” level signal to the light receiving control circuit 1
No. 1 input terminal D is applied.

The input terminal E of the light receiving control circuit 11 is connected to the synchronizing line 3 via the input circuit 17, and the output terminal F is connected to the synchronizing line 3 via the output circuit 18.
The light-receiving control circuit 11 is adapted to input the synchronization reference signal from the light-emission control circuit 4 via the input circuit 17 and the synchronization line 3. Further, the light reception control circuit 11 is configured to transmit a light emission control signal, which will be described later, to the light projector 1 side via the output circuit 18 and the synchronization line 3.

The detection output circuit 19 for outputting the object detection signal to the outside is connected to the output terminal G of the light reception control circuit 11, and when the output signal is given from the light reception control circuit 11, the object is output to the external terminal H. It is designed to output a detection signal.

Next, the operation of this embodiment will be described with reference to FIGS. The light projecting control circuit 4 and the light receiving control circuit 11 are adapted to execute the detecting operation in accordance with the light projecting control program and the light receiving determination control program shown in FIGS. 2 and 3, respectively. Then, in the following, the signal output states of the respective parts will be shown according to the time chart of FIG. 4, and will be described separately for the following three detection operation modes. That is, there are (1) a light-shielding operation by a light-shielding object and a detection operation when no sputter light is incident, (2) a detection operation when a sputter light is incident, and (3) a light-shielding detection operation by a light-shielding object.

(1) Detection operation when there is no light blocking by a light blocking object and incidence of sputtered light This is because there is no light blocking object in the detection area, and disturbance light such as spattering light does not enter and light is continuously received. In this case, all the light emitted from the LEDs 8a to 8d of the light projector 1 are received by the corresponding photodiodes 16a to 16d of the light receiver 2. In the following description, the initial operation when the power is turned on is included. To describe.

First, the light-emission control circuit 4 starts the light-emission control program when power is supplied, and the synchronization reference signal S14 (see FIG. 4) is generated based on the internally generated frequency signal.
Is output (step R1). The synchronization reference signal S14 is a signal indicating the start of one scan of the light projecting and light receiving operations, and is the output terminal B of the light projecting control circuit 4, the synchronizing line 3, and the like.
The signal is supplied to the light receiving control circuit 11 via the input circuit 17 and the input terminal E of the light receiving control circuit 11.

Next, the light emission control circuit 4 resets the shift register 5 (step R2), and then shifts the shift register 5 by "1" (step R3).
The first light projection signal S1 (see FIG. 4) is output from the output terminal A (step R4). As a result, the "H" level signal S2 (see FIG. 4) is output from only Q1 of the output terminals Q1 to Q4 of the shift register 5, so that A
Only the ND circuit 6a outputs the “H” level signal S6 (see FIG. 4) only during the period when the light projecting signal S1 is applied, and the pulsed light is generated by energizing the LED 8a through the drive circuit 7a. Outputs toward the detection area.

The light emission control circuit 4 then carries out step R5.
It is determined whether or not the light emission control signal S15 (see FIG. 4) is given from the light receiving control circuit 11 side, and when "NO" is determined, the process proceeds to step R6 and ends for all optical axes. If it is not completed, the process returns to step R3 to repeat the above steps R3 to R6 to perform the light projecting operation on the remaining optical axes,
When one scan is completed, the process returns to step R1.

When the light projecting control circuit 4 starts the light projecting operation as described above, the light receiving control circuit 11 responds to this.
It operates as follows according to the light reception determination control program shown in FIG. That is, when the program is started, the light receiving control circuit 11 is in a state of waiting for the synchronization reference signal S14 to be input in step T1, and the light emission control circuit 4 outputs the output circuit 9, the synchronization line 3, and the like. Input circuit 17
When the synchronization reference signal S14 is applied to the input terminal E via the, the determination is "YES" here, and the process proceeds to step T2.

Next, the light receiving control circuit 11 clears the value of the internal counter C (C ← 0) and shift register 1
2 is reset, and then the value of the counter C is incremented by "1" (C ← C + 1) and the shift register 1
A signal is given to shift 2 by "1" (step T
3) Then, in the next step T4, the value of the internal counter N is cleared to "0", and the process proceeds to step T5.

As a result, only the P1 of the output terminals P1 to P4 of the shift register 12 outputs the "H" level signal S2 (see FIG. 4), and the analog switch 13a.
The signal input to is validated and input to the comparator 14. At this time, since it is considered that there is no object that blocks the light in the detection area, the photodiode 1
6a is in a state in which the pulsed light from the LED 8a is incident, and the received light signal S10 amplified through the light receiving circuit 15a is received.
(See FIG. 4) is input to the analog switch 13a. Therefore, the received light signal S10 is transmitted to the comparator 1
4 to the input terminal D of the light receiving control circuit 11.

Then, the light receiving control circuit 11 inputs the light receiving signal given from the comparator 14 to the input terminal D as the light receiving signal data D (step T5). In this case, the light reception control circuit 11 inputs the light reception signal data D as data of "1" when it is a signal exhibiting a light entering state and "0" when it is a signal exhibiting a light shielding state. There is.

Subsequently, the light-receiving control circuit 11 initializes the internal data K (C) (C = 1, 2, 3, 4) to a value which is initially set in a state of being cleared to "0" and the first time. It is determined whether or not the received light signal data D corresponding to the C-th optical axis in scanning is equal (step T6). In this case, since the received light signal data D is assumed to be the signal "1" indicating the received light state, it is not equal to the value of K (C) "0", and the received light control circuit 11 judges "NO". In step T7, the value of N is incremented by "1" (N ← N + 1) to be "1".

In the next step T8, the light receiving control circuit 11
Is "NO" because the value of N at that time is "1".
Then, the process proceeds to step T9, where the light emission control signal S15 is output from the output terminal F and step T5 is executed.
Will come back to. As a result, the light receiving control circuit 11
When the next light projecting timing comes, the light receiving signal from the same photodiode 16a is validated again without shifting the output state of the shift register 12.

Further, in the light projecting control circuit 4, the light projecting control signal S15 is inputted to the input terminal C through the output circuit 18, the synchronizing line 3 and the input circuit 10 on the side of the light receiver 2, as described above. When the process moves from step R4 to step R5, the judgment is "YES". This allows
The light projecting control circuit 4 returns to step R4 and outputs the pulsed light from the LED 8a in the same state again. In other words, the output state of the shift register 5 is not shifted at the next light projecting timing, and the LED 8a that is the same as the previous projecting light is projected again.

Since the light receiving control circuit 11 validates the light receiving signal of the same photodiode 16a for the light projecting operation from the light projector 1 side as described above, the light receiving signal data D is input again ( At step T5), since the data "1" indicating the light receiving state is input at this time, if "NO" is judged again at step T6 and the process proceeds to step T8 through step T7, the value of N is "2" here. Therefore, it is determined to be "YES" and the process proceeds to step T10.

The light receiving control circuit 11 executes this step T10.
, The value of the received light signal data D at that time is set to K (1)
Substituting it as the value of and proceeding to step T11, all K
It is determined whether or not the value of (C) (C = 1, 2, 3, 4) is substituted as the light reception signal data “1” indicating the light reception state. In this case, only the value of K (1) is determined. Is "1" and K
Since the values of (2) to K (4) are still "0", the determination is "NO" and the process proceeds to step T12.

In this initial state, K as described above.
Since all the values in (C) are not the light-reception signal data "1" indicating the light-reception state, the light-reception control circuit 11 outputs the object detection signal from the output terminal G and outputs it to the detection output circuit 19 in step T12. After the turning-on operation is performed, the process returns to step T3 via step T13, and thereafter, steps T3 to T13 described above are repeatedly executed for all optical axes. Then, the light receiving control circuit 11 makes all K
When (C) (C = 1, 2, 3, 4) becomes “1”, it is determined “YES” in step T11, the process proceeds to step T14, the output is turned off, and the process proceeds to step T13. If YES is determined, the process returns to step T1.

Now, as described above, when the initial state is completed, it is considered that there is no light-shielding object in the detection area and no sputtered light enters in this state. When T1 to T5 have passed and the process proceeds to step T6, all Ks are set in the initial state.
Since (C) is "1" and each received light signal data D has the value "1" which indicates the light receiving state, it is determined to be "YES" and the process jumps to step T13. , The process returns to step T3 and is repeated until the process is completed for all the optical axes, and then the process returns to step T1 and the state in which the object detection signal is not output continues.

(2) Detection operation when sputtered light is incident Next, the sputtered light as ambient light is the photodiode 1
The detection operation will be described by taking the case of incidence on 6b as an example. When the light emission control circuit 4 performs the light emission operation according to the light emission control program in the same manner as described above, the light reception control circuit 11 also performs the light reception determination operation according to the light reception determination control program in the same manner as described above.

At this time, for example, strong sputtered light is generated immediately before the LED 8b outputs pulsed light.
6b, when the LED 8b outputs pulsed light by the light projecting signal S7a, the photodiode 16
Even if the light receiving signal of b is validated, the negatively inverted level of the light receiving signal due to the sputtered light at that time is larger than the level of the light receiving signal from the LED 8b, so that the light receiving signal at that time is buried as a whole. It becomes like the light reception signal S11a (the light reception signal of only the sputter light at this time is S in FIG. 4).
11a by a broken line).

As a result, the level of the light receiving signal becomes lower than the determination level in the comparator 14 even though there is no light-shielding object in the detection area. Therefore, the light receiving control circuit 11 performs the step T5. At this time, the light-reception signal data "0" which indicates the light-shielded state is input, and at step T6, "NO" is determined and steps T7 and T8 are entered.
After that, the projection control signal S15 is output in step T9, and the process returns to step T5 again.

As a result, the light projecting control circuit 4 outputs the light projecting signal S7b so that the same LED 8b again outputs the pulsed light in the same manner as described above, and the light receiving control circuit 11 receives the light from the same photodiode 16b. The output signal S3 is output from the shift register 12 so as to validate the signal, and the light reception signal S11b is input.

In this case, since the light-shielding object does not exist, when the transient sputtered light disappears, the pulsed light from the LED 8b is received by the photodiode 16b as the received light signal data "1" indicating the normal light receiving state, and the light receiving control is performed. Circuit 1
It will be input to 1. Then, the light receiving control circuit 11
Is judged to be "YES" because the data K (2) when C = 2 at step T6 is "1" and jumps to step T13. As a result, the optical axis is blocked. It is determined that the object was not in a light-shielded state.

(3) Detecting operation by light-shielding object during light-shielding Next, the case where the optical axis formed by the LED 8b and the photodiode 16b is shielded in the state where the light-shielding object is actually present in the detection area will be described as an example. The detection operation will be described. The light reception control circuit 11 receives the light reception signal S11 when the pulsed light output from the LED 8b by the light projection pulse S7c does not enter the photodiode 16b in the same manner as described above.
Since c becomes the light reception signal data "0" which indicates the light shielding state, the light emission control signal S15 is output.

Then, even when the light emitting signal S7d is given to output the pulsed light from the same LED 8b again,
Since the light reception signal S11d becomes the light reception signal data “0” which indicates the light shielding state due to the light shielding, the light reception control circuit 11 determines “NO” in step T6, and further,
Even in step T8, it is determined to be “YES” and step T10
, And the value of the data D at that time is substituted into K (2).
It will move to 12.

As a result, the light-reception control circuit 11 outputs the object detection signal S16 from the output terminal G to output the detection output circuit 19
To perform output operation. It should be noted that after this, similar detection operations are performed for other optical axes.

According to this embodiment as described above, when the light receiving control circuit 11 receives the light receiving signal exhibiting the light blocking state, the light projecting control signal is given to the light projecting control circuit 4 side through the synchronizing line to obtain the same light. Since the axis light-projecting and light-receiving operations are performed and it is determined that a light-shielding object is present in the detection area when a light-reception signal that repeatedly exhibits a light-shielding state is input, it is possible to avoid a transient light such as sputtered light. Even when a received light signal exhibiting a light blocking state is detected by the disturbance light entering the photodiodes 16a to 16d, the detection operation is immediately repeated for the optical axis to wait until the next scanning timing. Without this, it is possible to quickly determine the light blocking state while preventing erroneous detection due to ambient light.

Further, with such a structure, even if the number of optical axes set by the light projector 1 and the light receiver 2 is increased, there is detection of a light blocking state and incidence of disturbance light such as sputtered light. Even in such a case, the light-shielded state can always be detected quickly regardless of the number of optical axes.

In the above embodiment, the synchronizing line 3 for synchronizing the light transmitter 1 and the light receiver 2 is used as the signal transmitting means. However, the present invention is not limited to this, and the synchronizing line 3 may be used. A signal transmission line may be provided separately from.

In the above embodiment, the case where the synchronizing line 3 is provided as the signal transmitting means has been described, but the present invention is not limited to this. For example, an LED for transmitting a light projecting control signal to the light receiver 2 side is provided. Alternatively, a configuration may be employed in which a light receiving element such as a photodiode is provided on the side of the projector 1 for transmitting and receiving a signal by an optical signal. In this case,
By applying it to an area sensor of the type that does not use a synchronization line, it becomes possible to completely eliminate the wiring between the light emitter and the light receiver.

In the above embodiment, the case of applying to a multi-optical axis photoelectric switch having four optical axes has been described. However, the present invention is not limited to this, and it is also possible to apply to an optical switch having more optical axes. However, similar to the above, it is possible to perform a quick object detection operation while preventing erroneous detection.

Further, in the above embodiment, when the light receiving signal exhibiting the light blocking state is input, the light emitting control signal is output only once and the light receiving operation is repeatedly performed on the same optical axis. However, the present invention is not limited to this. Instead, for example, a configuration may be adopted in which the detection of the object is determined by performing the light receiving operation repeated twice or more.

In addition, in the above embodiment, the case where the synchronization reference signal for performing the light projecting operation is generated on the light projecting control circuit 4 side has been described, but the present invention is not limited to this.
The light receiving control circuit 11 side may generate the synchronization reference signal.

Further, in the above-described embodiment, when the light receiving signal exhibiting the light blocking state is detected, the light projecting / receiving operation is repeatedly performed with the same optical axis, and the same optical axis is repeated when the light blocking state is changed to the light receiving state. Although the light emitting / receiving operation is carried out in the above, the purpose is to prevent the adverse effect of the sputtered light. Therefore, the present invention is not limited to this. It may be configured such that the light incident state is determined based on

[0057]

According to the multi-optical axis photoelectric switch of the present invention,
The light projecting control means sequentially performs light projecting operation on each light projecting element of the light projecting section at a predetermined light projecting timing, and the light receiving control means responds to the light receiving signal of each light receiving element of the light receiving section. Input in a state of being synchronized with, and when any of the light receiving elements receives a light receiving signal exhibiting a light blocking state, the light emitting control signal is given to the light emitting control means through the signal transmitting means and the light receiving is performed. The element is made to carry out the light receiving operation a plurality of times in succession, and the light emitting control means is made to make the same light emitting element to carry out the light emitting operation a plurality of times in succession. Since the object detection signal is output when the light-receiving signal indicating the state is output, it is determined that the light-shielding state is present.Therefore, by receiving ambient light such as welding spatter light from the light-receiving element, Is it receiving light However, if a received light signal that is in the light-shielded state is output, it is not necessary to determine this as the light-shielded state based on the fact that the ambient light is transient. It is possible to detect the light blocking state quickly without waiting until one scan is completed.
Further, by performing the detection operation in this way, there is an excellent effect that the quick detection operation can always be performed regardless of the number of optical axes.

[Brief description of drawings]

FIG. 1 is an electrical configuration diagram showing an embodiment of the present invention.

FIG. 2 is a flowchart of a light emission control program.

FIG. 3 is a flowchart of a light reception detection control program

FIG. 4 is a time chart showing a signal output state of each part.

[Explanation of symbols]

1 is a light emitter, 2 is a light receiver, 3 is a synchronization line (signal transmission means), 4 is a light emission control circuit (light emission control means), 5 is a shift register, 6a to 6d are AND circuits, and 8a to 8b are LE.
D (projection element), 9 is an output circuit, 10 is an input circuit, 11
Is a light receiving control circuit (light receiving control means, determination means), 12 is a shift register, 13a to 13d are analog switches, 1
4 is a comparator, 15a to 15d are light receiving circuits, 16a
16d is a photodiode (light receiving element), 17 is an input circuit, and 18 is an output circuit.

Claims (1)

[Claims] 1. A light projecting section having a plurality of light projecting elements, a light receiving section having a plurality of light receiving elements provided in a one-to-one opposed relationship with each light projecting element of the light projecting section, and the light projecting section. Each of the light projecting elements is sequentially projected at a predetermined light projecting timing, and when a light projecting control signal is given, the light projecting element operated at that time is continuously projected several times. And a light receiving signal indicating a light blocking state is input by synchronizing the light receiving signals of the respective light receiving elements of the light receiving unit with the light projecting timing of the corresponding light projecting elements and enabling the light receiving signals. Sometimes the light emission control signal is output, and at the same time, the light reception control means for controlling the light receiving element that has received the light to perform the light reception operation a plurality of times continuously, and the light emission control signal output from the light reception control means. The signal transmitted to the emission control means The light receiving control means includes a transmitting means and a determining means for determining a light blocking state and outputting an object detection signal when a light receiving signal indicating a light blocking state is output from the same light receiving element a plurality of times. A multi-optical axis photoelectric switch.