JPH11112318A - Detection device and its output setting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize automatic teaching including output setting by deciding an output state according to the passing times of an object of detection of a maximum and a minimum range. SOLUTION: A photodetection part 3 receives reflected light from a body detection area and outputs it to a control part 4A. At the control part 4A, a received light quantity measurement part 12 measures received light quantity data in the maximum range(MAX range) an minimum range(MIN range) and a staying time data measurement part 13 measures the times of the MAX range and MIN range. Only when the received light level is in the MAX range and MIN range, the mean value of the received light quantity and the stay time are measured and when the received light level becomes larger than a threshold value, a body detection signal is turned on. When the time when the level is less than the MAX value is long, the output is so set that the time zone of the low received light quantity level is placed in a detection state for a work. Consequently, a body detection signal that a user desires can be outputted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a detection device having a feature in output setting of a photoelectric sensor, a proximity sensor, and the like, and to an output setting method thereof.

[0002]

2. Description of the Related Art Conventionally, when an object to be detected (hereinafter also referred to as a work) passing through a transport line or the like is detected using a photoelectric sensor, it is necessary to set a threshold value for the photoelectric sensor or the like. When setting the threshold value, a method of sampling the light reception level in a state where the work is arranged at a predetermined position, sampling the light reception amount in a background state after removing the work, and setting the threshold value based on each light reception amount ( Two-point teaching). Further, a method of setting a threshold value only in a state where a work is arranged at a predetermined position (one-point teaching) is also used.

[0003] As a method for teaching without such manual intervention, auto-teaching is used. When a work is sequentially conveyed on a conveyance line or the like, a teaching signal is input to the photoelectric sensor for a certain period of time as shown in FIG. In this method, while the teaching signal is being input, the photoelectric sensor performs sampling at regular intervals, and sets a threshold based on the maximum and minimum values of the amount of received light during this period.

[0004]

However, after setting the threshold value in this way, it is necessary to set whether the output is turned on when the detection signal exceeds the threshold value or when the detection signal is lower than the threshold value. For example, in a photoelectric sensor, it is necessary to set an object detection state (dark on) when the light reception level is low or an object detection state (light on) when the light reception level is high by using an output switch or the like. is there. Therefore, the conventional auto-teaching method has a drawback that complete auto-teaching including output setting cannot be realized.

The present invention has been made in view of such a conventional problem, and has as its object to automatically set an output based on a passing time of a workpiece and a background.

[0006]

According to a first aspect of the present invention, there is provided a detecting unit for outputting a detection signal according to an external physical state, a measuring unit for discriminating an output obtained from the detecting unit,
A maximum value detection unit that detects a maximum value of a detection signal obtained from the detection unit during teaching, a minimum value detection unit that detects a minimum value of a detection signal obtained from the detection unit during teaching, and the maximum value and the minimum value A predetermined time range including the maximum value and the minimum value detected by the detection unit as a maximum value range and a minimum value range, and a stay time data measurement unit that holds stay time information passing through the maximum value range and the minimum value range; An output setting unit that sets an output ON state for a shorter one of the maximum value stay time and the minimum value stay time measured by the stay time data measuring unit.

The invention according to claim 2 of the present application is an output setting method in a detection device for detecting detection targets sequentially passing by comparing a detection signal according to an external physical state with a threshold value and outputting a detection result signal. The maximum value of the detection signal is determined at the time of teaching, the minimum value of the detection signal is determined at the time of teaching, and a predetermined range including the determined maximum value and the minimum value is defined as a maximum value range and a minimum value range, respectively. It is characterized in that the stay time data in the range and the minimum value range are measured, the stay time data in the maximum value range and the stay time data in the minimum value range are compared, and a short time is set to be in the output ON state.

[0008]

FIG. 1 is a block diagram showing a configuration of a photoelectric sensor according to a first embodiment of the present invention. In the photoelectric sensor 1A according to the present embodiment, the light projecting unit 2 drives a light projecting element that emits light at a single cycle or a plurality of wavelengths at a fixed cycle, and the light receiving unit 3 emits light reflected from the object detection area. The light is received, converted into an electric signal, and output to the control unit 4A. The control unit 4A is constituted by, for example, a microcomputer and has the following functions. The measuring unit 5 in the control unit 4A generates a light emitting pulse at regular intervals, drives the light emitting unit 2, determines a light receiving level from the light receiving unit 3, and outputs an object detection signal. In addition to the measuring unit 5, the control unit 4A detects a maximum value and a minimum value and detects and holds a maximum value, a minimum value detecting unit 7, and sets a threshold value based on the held maximum value and minimum value of the received light level. A threshold setting processing unit 8, a sampling processing unit 9 for emitting and receiving light to sample the amount of received light, and a memory unit 1 for holding data of the amount of received light.
It has a cycle determination unit 11 that determines whether 0 and a predetermined number of cycles have been completed. Furthermore, the maximum value range (MA
X-range), light-receiving-amount data measuring unit 12 for measuring light-receiving amount data in a minimum value range (MIN range), MAX range, MIN
A stay time data measurement unit 13 and an output setting unit 14 that stay in the range are provided. The received light amount data measuring unit 12 is MAX
The average value of the data of the received light amount in the range and the MIN range is measured. The stay time data measuring unit 13 measures the time in the MAX range and the MIN range. The output level is identified and set at each output level.
The external input unit 21 outputs a teaching input directly input from another device or a user to the control unit 4A as described later, and the external output unit 22 outputs an answerback signal at the end of the teaching and a measurement unit 5 from the measuring unit 5. Is output to the outside.

FIGS. 2A and 2B are diagrams showing a configuration of an external device connected to the photoelectric sensor. As shown in the figure, a programmable controller 30 or a manual input switch means or the like is alternatively connected to the photoelectric sensor. FIG.
When the programmable controller 30 is connected as shown in FIG.
1 is an external input unit 2 on the photoelectric sensor side via the output unit 32
1 is input with a trigger signal for starting teaching. When the photoelectric sensor 1 has successfully completed the teaching,
An answerback signal is output from the external output unit 22.
The input unit 33 of the programmable controller 30 is connected to the external output unit 22 of the photoelectric sensor 1, and upon receiving this signal, the programmable controller 30 can determine that the threshold has been updated. Further, the presence or absence of an object can be identified on the programmable controller side by the object detection signal transmitted thereafter. After outputting the teaching signal, the programmable controller determines that the measurement information from the photoelectric sensor is invalid until the answerback signal is detected, and that the measurement output after outputting the answerback signal is valid.

In the photoelectric sensor 1A, a manual input switch 34 is connected to the external input section 21 as shown in FIG.
A display 35 for confirmation may be connected to the external output unit 22. When a trigger signal for starting the teaching is input from the manual input switch 34 after connecting in this manner, an answer back signal after the end of the teaching is input to the display 35 for confirmation, and the end of the teaching can be confirmed.

Next, a threshold and output setting process according to the first embodiment of the present invention will be described with reference to flowcharts and time charts. As shown in FIG. 3A, the photoelectric sensor 1A according to the present embodiment is used for detecting the work 36 by transferring the work 36 at a substantially constant interval on a transfer line such as a conveyor. I do. When detecting such a work, the photoelectric sensor 1
When a threshold value is set for A, a trigger signal for starting teaching is input to the photoelectric sensor 1A from the programmable controller 30 or the manual input switch 34 as described above.

Next, the operation of this embodiment will be described with reference to FIGS.
This will be described with reference to the flowchart of FIG. In this embodiment, when the teaching process is started, first, in step S
In step S1, a sampling process is performed, and in step S2, the first received light amount is stored in the MIN buffer and the MAX buffer of the memory. Next, in step S3, a sampling process is performed, and it is determined whether the obtained amount of received light exceeds the value of the MAX buffer and whether it is less than the value of the MIN buffer (steps S4, S5). If the value exceeds the MAX value, the process proceeds to step S6, where the MAX buffer is updated, and the MAX counter flag and the MAX counter are cleared (step S7). If the value is less than the value in the MIN buffer, the process proceeds to step S8 to update the MIN buffer, and proceeds to step S9 to clear the MIN flag and the MIN counter. Then, returning to step S3, the sampling process is performed, and the same process is repeated.

If the amount of received light is a value between the MAX and MIN buffers, the process proceeds from steps S4 and S5 to step S10 to check whether the value of the MAX buffer was updated last time. If it has been updated, the process proceeds to step S11 and M
The AX counter flag is set, and the process returns to the loop of step 3. If the MAX value has not been updated last time in step S10, the process proceeds to step S12 to check whether the value of the MIN buffer has been updated last time. MI
If the N buffer has been updated, the process proceeds to step S13 to set the MIN counter flag, and returns to step S3. In steps S10 and S12, the MAX buffer
If the MIN buffer has not been updated, the process proceeds to step S14 in FIG. 5 to check whether the MAX counter flag has been set. If the counter flag has been set, the process proceeds to step S15, where MA
The X counter is incremented, and if this flag has not been set, the process proceeds to step S16 without performing the process of step S15, and it is determined whether or not the MIN counter flag has been set. If the flag is set, the process proceeds to step S17 to increment the MIN counter. If the flag is not set, the process proceeds to step S18 without performing this process, and whether the MAX counter and the MIN counter have reached predetermined values. Check. This predetermined value is set to an appropriate value that can detect that there is no change because the light reception level continuously changes before and after the work detection, and then stops changing multiple times based on the sampling timing and the moving speed of the work. Shall be kept.

In this way, when both counter values reach the specified values, the maximum value and the minimum value include both the light receiving levels of the presence or absence of the object, and one work has passed (one cycle). I understand. Therefore, the process proceeds to step S19 to determine whether or not a predetermined number of cycles has been reached. If the number of cycles has not reached the predetermined number, the process returns to step S3 to repeat the same processing. If the number of cycles reaches the predetermined number, a threshold setting process is performed in step S20. The threshold value setting process is set based on the maximum value and the minimum value held in the MAX buffer and the MIN buffer that have already been obtained. For example, the threshold value is set to an intermediate value between them. In this way, the threshold can be automatically set using the teaching input as a trigger.

Here, the control section 1A executes step S
The functions of the sampling processor 9 are achieved in steps S1 and S3, and the functions of the maximum detector 6 for detecting the maximum in steps S4 and S6 and the minimum detector 7 for detecting the minimum in steps S5 and S8. Have achieved. In steps S7 and S9 and steps S10 to S18, it is determined whether or not the detection signal continuously updates the maximum value and the minimum value. If the detection signal is not continuously updated a predetermined number of times, one cycle of passing the detection target is determined. The function of the determination unit 11 is achieved. Further, the function of the threshold value setting processing unit 8 for setting the threshold value based on the maximum value and the minimum value obtained during at least one cycle in steps S19 and S20 is achieved.

Next, the output setting process will be described with reference to the flowchart of FIG. 6 and the time chart of FIG. After setting the threshold value as described above, in step S31, the MAX range and the MIN range are obtained from the maximum value stored in the MAX buffer and the minimum value stored in the MIN buffer. The MAX range and the MIN range are predetermined ranges including the maximum value and the minimum value as shown in FIG. 7, and are set so as not to overlap each other. Then, the process proceeds to step S32 to perform a sampling process to obtain the amount of received light. Then, in a step S33, it is determined whether or not the light receiving amount is within the MAX range and the MIN range. If within the MAX range, step S3
5, In S36, the received light amount data and stay time data in the MAX range are accumulated. Similarly, if the received light amount is within the MIN range, the received light amount data and stay time data of the MIN range are accumulated in steps S37 and S38. At this time, the stay time data holds the integrated value, and the received light amount data holds the average value within the stay time of the MAX range and the MIN range, respectively. If it is not the MAX range or the MIN range, the process proceeds to step 39 without performing these processes, and it is determined whether or not the change from the MAX range to the MIN range has reached the set number of times. If the number has not been reached, the process returns to step S32 and the same processing is repeated. In this case, as shown in FIG.
Only when it is within the range, the average value of the received light amount and the stay time can be measured, and the data as shown in FIGS. 8A and 8B is held. For example, when data in the MAX range and the MIN range is obtained five times, the data is totaled. On the maximum value side shown in FIG. 8A, the minimum value of V _{MAX and} the minimum value of T _MAX are finally determined. Determined data. Similarly, on the minimum value side shown in FIG. 8B, the maximum value of V _MIN of the received light amount and the minimum value of V _MIN as the stay time are determined as the final decision data.

Next, it is determined which of the T _MAX minimum value and the T _MIN minimum value is shorter. For example the smaller the time T _MAX, a high light receiving level as shown in FIG. 7 (a) M
The AX side can be determined to be in the work detection state, and the MIN side with a low light receiving level can be determined to be the background. Accordingly, the output is such that the object detection signal is turned on when the light receiving level becomes higher than the threshold value. If the time during which the MAX value has been entered is long as shown in FIG. 7B, the output is set so that the workpiece is detected in the time zone where the light reception level is low.

This eliminates the need for the user to select either dark-on or light-on again, allows the user to output an object detection signal desired by the user, and enables complete auto-teaching. The above-mentioned threshold value may be corrected based on the minimum value of V _{MAX and} the maximum value of V _MIN obtained at this time, and the output is set by merely measuring the stay time without accumulating the received light amount. You may make it. When the output setting process is completed, an answerback signal is output to the programmable controller 30 and the process proceeds to the measurement process.

FIG. 9 is a flowchart showing the measuring process. When the measuring process is started, first, in step S51, an external input is monitored to determine whether or not there is a teaching input. If there is a teaching input, the process proceeds from step S52 to step S1 to perform the above-described teaching process. If no teaching input is detected, step S
At 53, the light is projected from the light projecting unit 2 to the object detection area,
The light receiving level from the light receiving unit 3 is detected. Then, in step S55, the presence or absence of the work is determined based on whether or not the light receiving level is exceeded. Then, the process proceeds to step S56, in which the determination result is output from the external output unit 22 to the outside. This allows the programmable controller 30 to recognize the signal output from the external output unit 22 as an object detection signal.

Next, a photoelectric sensor according to a second embodiment of the present invention will be described. FIG. 10 is a block diagram of a photoelectric sensor according to the second embodiment. The same parts as those in the above-described first embodiment are denoted by the same reference numerals, and detailed description is omitted. The photoelectric sensor 1B according to the present embodiment is different from the photoelectric sensor 1B in part of the configuration of the control unit 4B. That is, the control unit 4B obtains an initial light receiving amount necessary for recognizing a passing cycle of the work, and compares the received light amount of the initial value with the obtained light receiving amount as described later, and And a data comparing unit 42 for detecting the maximum value and the minimum value.
Other configurations are the same as those of the above-described embodiment.

FIG. 11 is a flowchart showing a teaching process after a teaching signal is input. When teaching is started, first, a sampling process is performed in step S1, and in step S62, the light receiving amount at that time is fixed. The width range is set up and down to be the initial range. For example, when a teaching input is given at time t ₁ in the background state as shown in FIG.
2 when the teaching input is given from the background as shown in (b) at time t ₂ of the intermediate state of the work detected, and teaching input at time t ₃ of the detection state of the workpiece, as shown in FIG. 12 (c) When given, the areas indicated by hatching in the figures are set as initial ranges. Then, in steps S63 and S64, the sampling process is repeated until the current value falls outside the initial range.
5, the program returns to the initial range by proceeding to S66, and thereafter, it is determined whether or not the initial range is deviated. For example, FIG.
In the state shown in (a), when the workpiece detection state is reached, the initial range is deviated, and the state returns to the background state. When the time t ₅ the next work close to the light receiving level rises, the flow proceeds to step S67 for deviating the initial range. FIG. 12 (b)
As shown in (2), even when teaching is started from a state intermediate between the background and the work, the light reception level is reduced again after the work reaches the work detection state once. Therefore, at the time t ₄ , the control returns to the initial range and is again out of the initial range.
Go to 7. Further, when teaching is started in the work detection state, as shown in FIG. 12C, the state once detects the background, and then the next work is detected again, so that the signal from the work decreases. out of the initial range to the time t _7, the process proceeds to step S67. Step S67
Then, when it is out of the initial range, it is determined whether or not the light receiving level has changed across the initial range. If it does not change across the initial range, it is determined that the teaching input has been made on the work or the background as shown in FIG. 12A or 12C, and one cycle has been recognized so far (step S68). . On the other hand, in step S67, if the initial range is crossed and deviated from the initial range (time t ₄ ), it is determined that the teaching input has been made at the light receiving level intermediate between the background and the work as shown in FIG. A determination is made (step S69). In this case, steps S70 and S7 are performed again.
After returning to 1 and returning to the initial range, it is determined whether or not the initial range has been exceeded. After returning to the initial range again at time t ₆ in the case of FIG. 12 (b), since the outside of the initial range, it is determined that one cycle has elapsed at this time.

When it is determined that the cycle is one cycle, the process proceeds to step S72 from step S68 or S70, and it is determined whether or not a predetermined number of cycles has been reached.
Returning to the loop of S66, the same processing is repeated. After the sampling processing in steps S64, S66, and S71, the maximum and minimum values of the light reception level obtained at that time are updated and held. And step S72
When the number of set cycles has been reached, the process proceeds to step S73, and the threshold setting process is performed by the threshold setting unit 8. In the threshold setting process, for example, the median of the maximum value and the minimum value during the sampling process is set as the threshold. After ending the threshold setting process, the output setting process is performed using the maximum value and the minimum value, as in the first embodiment shown in FIG. When the output setting is completed, an answer back signal is output to the programmable controller 30 or the like. This allows the programmable controller to recognize that the teaching process has been completed normally. After setting the threshold value and the output, the process proceeds to the measurement processing routine.

In the flowchart shown in FIG. 11, steps S61, S64, S66 and S71 achieve the function of the sampling processing section 9, and
62 achieves the function of the initial value acquisition unit 41, and steps S63 to S70 determine data of one cycle of passage of the detection target based on the state of change from the initial range and data for determining the maximum value and the minimum value. The function of the comparison unit 42 is achieved, and steps S72 and S73 achieve the function of the threshold setting processing unit 8 that sets the threshold based on the maximum value and the minimum value obtained when the detection target passes at least one cycle. I have.

Next, a photoelectric sensor according to a third embodiment of the present invention will be described. FIG. 13 is a block diagram of a photoelectric sensor according to the third embodiment. The same parts as those in the above-described first embodiment are denoted by the same reference numerals, and detailed description is omitted. The photoelectric sensor 1C according to this embodiment differs from the control unit 4C in part of the configuration. That is, the control unit 4C calculates the difference between the light receiving levels by two consecutive samplings, and determines one cycle of the work passage and the maximum value and the minimum value during the work passage based on the level of the difference value. The light receiving cycle determining unit 52 is provided. The threshold setting unit 8 sets a threshold based on the light receiving level held during at least one cycle of the light receiving state.

Next, a teaching process according to the third embodiment will be described with reference to a flowchart of FIG. 14 and a time chart of FIG. In this embodiment, when the teaching process is started, the sampling process is first performed in step S81, and the first received light amount is stored in the area of the previous sampling value in the memory unit 10 in step S82. Then, the process proceeds to steps S83 and S84 to perform sampling processing at a fixed period, and stores the next received light amount obtained by the sampling processing in the current sampling value area. Next, in step S85, a difference value (= current sampling value−previous sampling value) is calculated from the previous and current sampling values. And step S
Proceeding to 86, the current sampling value is moved to the area of the previous sampling value. Next, the routine proceeds to step S87, where it is determined whether or not the difference value is within a predetermined range ± α. FIG. 15 is a time chart showing a light receiving level, a difference value, and a state determination result. Since the change in the threshold value is small within the range of ± α, the work can be determined to be state 1, that is, the state where the work is detected in this time and the state where the work is detected in the previous time or the light reception in the background state. Therefore, the received light amount is held as threshold setting data. If the difference value does not fall within this range in step S87, it is determined that the state 2 is a change state between the workpiece and the background, and is not stored as threshold setting data (step S89). Then, in step S90, it is determined whether or not the number of transitions from state 1 to state 2 has reached the set value, and if not, the process returns to step S83 to repeat the same processing. This set number must be two or more. When the transition from the state 1 to the state 2 has reached the set number of times, the process proceeds to step S91, and the threshold is set using the threshold setting data. For example, the threshold value is set to an intermediate value between the maximum value and the minimum value of the threshold value setting data. And step S92
To perform the same output setting processing as in FIG. After the output is set in this way, an answer back signal is output to the controller 30 side, and the flow proceeds to the measurement processing in FIG. In this way, teaching can be easily performed, and the threshold setting process can be performed even while the workpiece is passing.

Here, the control section 4C determines in step S8
1, the function of the sampling processing unit 9 is achieved in S83, and in steps S82, S84, S86, the function of the difference value calculating unit 51 for calculating the difference value between the detection signals is achieved. Further, in steps S87 to S89, the function of the light receiving cycle determining unit 52 for determining one cycle of the passage of the detection object based on the state of the change of the absolute value of the difference value and determining the maximum value and the minimum value therebetween is achieved. Steps S90 and S91 achieve the function of the threshold value setting processing unit 8 that sets a threshold value based on the maximum value and the minimum value of the detection signal obtained while the passage of the detection target in at least one cycle is determined.

Next, a fourth embodiment of the present invention will be described with reference to the block diagram of FIG. In the present embodiment, the third embodiment can be applied to a photoelectric sensor in which the sampling period is randomized in order to prevent disturbance light and to prevent mutual interference. This embodiment is different from the above-described third embodiment in that the difference value calculating unit 5
The only difference is that a differential value calculation unit 61 for calculating a differential value is provided instead of 1, and the other points are the same as in the third embodiment. In this embodiment, when the sampling interval is T in step S85 of the flowchart shown in FIG. 14, a differential value is calculated by the following equation instead of the difference value between the previous and current sampling. Differential value = |
The previous sampling value | − | the current sampling value | ÷ T The differential value is obtained as described above. In step S87, states 1 and 2 are determined based on the differential value, and a threshold value is set as in FIG.

In this way, for a photoelectric sensor whose sampling interval is not constant, the teaching input is triggered in the same manner as in the third embodiment by using the differential value instead of the difference value according to the third embodiment. The threshold setting and the output setting can be automatically performed.

In each of the embodiments, a photoelectric sensor for determining the presence / absence of a normal object is described. However, the present invention is not limited to a sensor for detecting a normal object, and the present invention is not limited to FIG.
Mark 3 attached to the object on the line as shown in (b)
Needless to say, the present invention can be applied to a mark sensor that detects 7 as a workpiece. In each of the embodiments described above, the photoelectric sensor is described. However, the present invention is not limited to the photoelectric sensor, but may include various other types of detectors for detecting a physical state, such as a proximity sensor, a pressure sensor, an ultrasonic sensor, and the like. Can be applied to In the case of a photoelectric sensor, a light receiving signal is used as a detection signal. However, in a proximity sensor, a signal indicating a change in the oscillation state, for example, an oscillation amplitude signal is used as a detection signal. In the mark sensor, a detection signal is a light reception signal of reflected light from the mark, in the pressure sensor, a pressure signal introduced into the sensor, and in an ultrasonic sensor, an ultrasonic reception signal is a detection signal. In each embodiment, the threshold value is set based on the maximum value and the minimum value. However, a representative value near the maximum value may be used instead of the strict maximum value, or a margin level is subtracted from the maximum value. The maximum value may be determined using a value obtained by multiplying the maximum value by a constant slightly smaller than 1. Similarly, the minimum value may be a representative value near the minimum value, a value obtained by adding a margin level to the minimum value, or a value obtained by multiplying the minimum value by a constant slightly larger than 1. Further, the threshold value is set at the median of the maximum value and the minimum value in each of the above-described embodiments, but is not limited to the median value, and a value between them can be set as appropriate.

If the detection signal does not show the expected change when setting the threshold value, for example, if the MAX range and the MIN range are not appropriate and the normal operation cannot be performed in the first embodiment, the second operation is performed. In the above embodiment, a threshold setting error may be notified when there is no change from the initial range within the predetermined time or when the threshold does not return to the initial range within the predetermined time. Error processing is performed as a threshold setting error when the state determination cannot be performed accurately, such as when the difference value is not appropriate in the third embodiment, and when the differential value is not appropriate in the fourth embodiment. Is also good.

In each of the embodiments described above, the output ON state is set based on the maximum value and the minimum value obtained at the time of setting the threshold value. However, the maximum of the detection signal is set independently of the threshold value setting. Needless to say, a value and a minimum value may be obtained, and the output state may be set based on this.

[0032]

As described above in detail, according to the present invention, since the output state can be determined based on the passage time of the maximum value range and the minimum value range of the detection object, the automatic teaching including the output setting can be realized. The effect is obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a photoelectric sensor according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a photoelectric sensor according to the first embodiment of the present invention and a controller connected to the photoelectric sensor.

FIG. 3 is a schematic diagram showing a usage state of the photoelectric sensor according to the first embodiment of the present invention.

FIG. 4 is a flowchart (part 1) illustrating a threshold setting process of the photoelectric sensor according to the first embodiment of the present invention.

FIG. 5 is a flowchart (part 2) illustrating a threshold setting process of the photoelectric sensor according to the first embodiment of the present invention.

FIG. 6 is a flowchart illustrating an operation of an output setting process according to the first embodiment of the present invention.

FIG. 7 is a time chart showing changes in the light receiving level and stay time of the photoelectric sensor according to the first embodiment of the present invention.

FIG. 8 is a diagram illustrating an average light reception amount and a stay time in a MAX range and a MIN range of the photoelectric sensor according to the first embodiment of the present invention.

FIG. 9 is a flowchart illustrating measurement processing of the photoelectric sensor according to the first embodiment of the present invention.

FIG. 10 is a block diagram of a photoelectric sensor according to a second embodiment of the present invention.

FIG. 11 is a flowchart illustrating a threshold setting method according to a second embodiment of the present invention.

FIG. 12 is a graph showing a change in a light receiving level in a threshold value setting process of the photoelectric sensor according to the second embodiment of the present invention.

FIG. 13 is a block diagram illustrating a configuration of a photoelectric sensor according to a third embodiment of the present invention.

FIG. 14 is a flowchart illustrating a threshold setting method according to a third embodiment of the present invention.

FIG. 15 is a time chart showing a change in a light receiving level in a threshold value setting process according to the third embodiment of the present invention.

FIG. 16 is a block diagram illustrating a configuration of a photoelectric sensor according to a fourth embodiment of the present invention.

FIG. 17 is a diagram showing a light receiving level and a teaching input obtained by a conventional photoelectric sensor.

[Explanation of symbols]

 1A, 1B, 1C, 1D photoelectric sensor 2 light emitting unit 3 light receiving unit 4A, 4B, 4C, 4D control unit 5 measuring unit 6 maximum value detecting unit 7 minimum value detecting unit 8 threshold setting processing unit 9 sampling processing unit 10 memory unit DESCRIPTION OF SYMBOLS 11 Cycle discriminating part 12 Light reception amount data measuring part 13 Stay time data measuring part 14 Output setting part 21 External input part 22 External output part 30 Programmable controller 31 Programmable controller main body 32 Output part 33 Input part 34 Manual input switch 35 Display 41 Initial Value acquisition unit 42 Data comparison unit 51 Difference value calculation unit 52 Light receiving cycle determination unit 61 Differential value calculation unit

Continued on the front page (51) Int.Cl. ⁶ Identification code FI H01H 35/00 G01V 9/04 J

Claims (2)

[Claims] 1. A detecting unit that outputs a detection signal according to an external physical state, a measuring unit that discriminates an output obtained from the detecting unit, and detects a maximum value of a detection signal obtained from the detecting unit during teaching. A maximum value detection unit, a minimum value detection unit that detects a minimum value of a detection signal obtained from the detection unit during teaching, and a predetermined range including the maximum value and the minimum value detected by the maximum value and the minimum value detection unit. Is a maximum value range and a minimum value range, and a stay time data measurement unit that holds stay time information passing through the maximum value range and the minimum value range; and a maximum value stay time and a minimum value measured by the stay time data measurement unit. An output setting unit that sets any one of the value staying times to the output ON state. 2. An output setting method in a detection device for detecting a detection object sequentially passing by comparing a detection signal according to an external physical state with a threshold value and outputting a detection result signal, wherein the detection signal is provided during teaching. The maximum value of the detection signal is determined at the time of teaching, and the predetermined range including the determined maximum value and the minimum value is defined as the maximum value range and the minimum value range, respectively. An output setting method, comprising measuring time data, comparing the stay time data in the maximum value range and the stay time data in the minimum value range, and setting a short time to be in an output ON state.