JP2007121182A - Detection sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a detection sensor which measures a moving object with a relatively simple constitution. <P>SOLUTION: A photoelectric sensor 30 comprises a light projecting section 31, a light receiving section 33, a data processing section 40, an output circuit 51, an output circuit control section 55, and the like, and detects the position of a workpiece W by performing a light projecting operation and light receiving operation toward the moving workpiece W. In this case, a light receiving signal Cn output from the light receiving section 33 is inputted into a data processing section 40. Next, the data processing section 40 comprises a first data processing section 45, a second data processing section 47, and the like. When the workpiece does not exist in a measuring area and measurement is not performed correctly, the variation of the light receiving signal Cn appears large. But, this variation is monitored by the second data processing section 47, and the output operation of the output circuit 51 is stopped when the workpiece W is out of the measuring area. Thus, the result of measurement in a state where the workpiece W is out of the measuring area is not outputted to the outside. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a detection sensor.

Conventionally, sensors that detect the position, displacement, presence, etc. of an object are widely known. These include magnetic proximity sensors, ultrasonic sensors, photoelectric sensors, and the like. For example, in the case of a photoelectric sensor, the configuration includes a light projecting unit that projects light toward an object to be measured such as a workpiece, and a detection unit that includes reflected light reflected by the object to be measured and a light receiving unit. The position and displacement amount of the measurement object in the optical axis direction can be known based on the magnitude of the received light amount (Patent Document 1 and the like).
FIG. 9 shows an example in which measurement (detection operation) is performed on the position of a workpiece conveyed on a conveyance line using a photoelectric sensor, where 1 is a light projecting unit, 2 is a light receiving unit, Reference numeral 3 denotes a transfer line on which the workpiece W is transferred. In this apparatus, the light emitted from the light projecting unit 1 and reflected by the work W is received by the light receiving unit 2, and the position shift of the work W on the transport line 3 is detected based on the level of the amount of received light.

  That is, in the case where the workpiece W is transported on substantially the center Lc, which is the normal position of the transport line 3 (work W1), and in the case where the end of the transport line 3 is transported (work W2), the light receiving unit 2 and the work W1. Since the distance D between the detection surface P and W2 varies, the amount of received light changes accordingly. For example, in the workpiece W2 located far from the workpiece W1 when viewed from the light receiving unit 2, the reflected light spreads, and as a result, the amount of received light is reduced as compared with the case where the measurement is performed on the workpiece W1. In this way, by detecting the change in the amount of received light, it is possible to detect the displacement of the workpiece W in the optical axis direction (the vertical direction in FIG. 9).

Moreover, since this object is a moving object, the position detection sensor 5 is provided exclusively. The position detection sensor 5 detects whether or not the workpiece W is located in the measurement area, and when the workpiece W is within the measurement area, the position detection sensor 5 sets the measurement timing to perform measurement (light projection / light reception). To decide. If the position detection sensor 5 is not provided and the measurement is performed at random, even if the workpiece W is substantially at the center of the transfer line 3 as shown in FIG. 10, a part of the workpiece W is out of the measurement area. In some cases, the light from the light projecting unit 1 may be applied to the corners of the detection surface P. In such a case, regardless of the distance D between the two, the amount of reflected light itself reflected by the work W is reduced, so that the measurement cannot be performed correctly.
JP 56-71330 A

In the above structure, the position detection sensor 5 is provided to determine the measurement timing. However, providing such a sensor exclusively increases the number of parts and hinders cost reduction.
The present invention has been completed based on the above situation, and an object thereof is to provide a detection sensor capable of measuring a moving object with a relatively simple configuration.

As means for achieving the above object, the invention of claim 1 is characterized in that a physical quantity detection means for performing a detection operation on an object to be detected and outputting a detection signal corresponding to the level of the physical quantity obtained as a result, and the physical quantity detection. A sampling means for obtaining sampling data by sampling a detection signal output from the means at a predetermined timing, and detection by the physical quantity detection means based on a plurality of the sampling data obtained from the sampling means within a predetermined period. A detection sensor comprising a measurement means for measuring a measurement value as a result, and an output means for outputting in accordance with the measurement value measured by the measurement means, for the sampling data output from the sampling means, The amount of change in sampling data within the predetermined period is compared with a predetermined level, A discriminating means for discriminating whether the intelligence signal is in a stable state or an unstable state and outputting a discrimination signal according to the discrimination result; and a discrimination signal output from the discrimination means. It is characterized in that it comprises output control means for causing the output means to perform a preset output corresponding to the unstable state when the result is in an unstable state.
The “preset output” mentioned here includes stopping the output as one aspect.

  According to a second aspect of the present invention, a physical quantity detection unit that performs a detection operation on an object to be detected and outputs a detection signal corresponding to the level of the physical quantity obtained as a result, and a detection signal output from the physical quantity detection unit are set at a predetermined timing. Sampling means for sampling each time to obtain sampling data, measurement means for measuring a measurement value as a detection result by the physical quantity detection means based on a plurality of the sampling data obtained from the sampling means within a predetermined period, and An output means for outputting in accordance with the measurement value measured by the measurement means, wherein the sampling data output from the sampling means has a predetermined amount of change in the sampling data within a predetermined period. Based on the comparison with the level, whether the detection signal is stable or unstable A discriminating means for discriminating and outputting a discriminating signal according to the discriminating result, and a discriminating signal output from the discriminating means, and when the discriminating result is in an unstable state, the instability And a notification means for performing a predetermined notification operation corresponding to the state.

  According to a third aspect of the present invention, in the first or second aspect, the determination unit includes an extraction function unit that extracts a maximum value and a minimum value from a plurality of sampling data within the predetermined period, and an extraction function unit. A calculation function unit for calculating a difference between the maximum value and the minimum value, and a difference as the amount of change calculated by the calculation function unit is compared with the predetermined level to determine whether the detection signal is in a stable state or unstable. And a discrimination function unit for discriminating whether the state is present or not, and is characterized in that the discrimination signal corresponding to the discrimination result is output.

  According to a fourth aspect of the present invention, in the method according to the first or second aspect, the determination unit targets each divided period obtained by equally dividing the predetermined period so that at least two or more sampling data are acquired. An average value calculation function unit for calculating an average value of sampling data within the same divided period; and when the divided period is obtained by dividing the predetermined period into two, the two calculated by the average value calculating means When the difference between the average values is calculated and the divided period is obtained by dividing the period into three or more, the maximum value and the minimum value are selected from among the three or more average values calculated by the average value calculating means. And the difference between the amount of change calculated by the calculation function unit is compared with the predetermined level to determine whether the detection signal is in a stable state or an unstable state. To determine And a function unit has a feature where the output of the discrimination signal corresponding to the determination result.

  According to a fifth aspect of the present invention, in the method according to any one of the first to fourth aspects, the measuring means calculates an average value from the sampling data within the predetermined period, and calculates the average value as the measured value. The detection sensor according to any one of claims 1 to 4, wherein:

<Invention of Claims 1 and 2>
According to the present invention, based on the amount of change in the sampling data, it is determined whether the detection signal is in a stable state or an unstable state, and with this, the quality of the detection operation for the detected object is determined. did. In other words, if the detection signal is stable, the detection operation is good. Conversely, if the detection signal is unstable, the detection operation is bad. With such a configuration, the detection sensor itself can determine whether the detection operation is good or bad.

  According to the first aspect of the invention, when the detection signal is in an unstable state, the output means causes the output means to output according to the unstable state through the output control means. As a result, the content of the output can be made different depending on whether the detection operation is good or bad. On the other hand, in the invention of claim 2, when the detection signal is in an unstable state, a notification operation according to the unstable state is performed. As a result, the operator can be notified that the detection operation is defective.

<Invention of Claim 3>
According to the third aspect of the present invention, the difference between the maximum value and the minimum value of the sampling data is set as the change amount of the sampling data. With such a configuration, the amount of change can be obtained by a relatively simple subtraction process.

<Invention of Claim 4>
According to the fourth aspect of the present invention, the average value of the sampling data is calculated for each of the divided periods, and the difference between the maximum value and the minimum value of these average values is obtained, and this is used as the change amount of the sampling data. With such a configuration, it is possible to suppress the error compared to the case where the amount of change is simply determined based on the signal level difference, that is, even if there is an abnormal value in the data due to the influence of noise, This is because it is averaged.

<Invention of Claim 5>
The measurement value can be measured by picking up a specific value such as the maximum value, minimum value, or intermediate value from the sampling data, but if the average value of the sampling data is the measurement value, Errors can be suppressed. That is, even if there is an abnormal value in the data due to the influence of noise or the like, this is averaged.

<Embodiment 1>
A first embodiment of the present invention will be described with reference to FIGS.
In the present embodiment, the position of the workpiece W as an object to be detected conveyed on the conveyance line 20, specifically, the positional deviation of the workpiece W in the left-right direction in FIG. The detection is based on the signal level of the received light signal output from the detection sensor 30 (corresponding to the detection sensor of the present invention).

  In general, the photoelectric sensor 30 includes a light projecting unit (corresponding to the physical quantity detecting means of the present invention) 31, a light receiving part (corresponding to the physical quantity detecting means of the present invention) 33, a data processing unit 40, an output circuit (output of the present invention). 51, an output circuit control unit (corresponding to the output control means of the present invention) 55, and a memory 57.

Both the light projecting unit 31 and the light receiving unit 33 are arranged side by side on the conveyance line 20. The light projecting unit 31 includes a light projecting element such as an LED, and emits light toward the light projecting operation, that is, the transport line 20 based on a light projecting command from the data processing unit 40. And when the workpiece | work W which is a measuring object is located in a measurement area, the emitted light will be reflected by the side surface P, and this will be received by the light-receiving part 33. FIG. The light receiving unit 33 includes a light receiving element such as a photodiode, and outputs a light receiving signal having a level corresponding to the amount of received light.
The light projecting / receiving operation by the light projecting unit 31 and the light receiving unit 33 is “corresponding to the detection operation of the present invention”, and the light reception amount obtained as a result is “corresponding to the physical quantity of the present invention”. The light-receiving signal converted into is equivalent to the “detection signal of the present invention”.

  The light projecting and receiving operations by the light projecting unit 31 and the light receiving unit 33 are performed randomly regardless of whether or not the workpiece W is located in the measurement area. A light reception signal is output over time.

  FIG. 2 is a diagram illustrating a transition of a light reception signal output from the light receiving unit 33 when the workpiece W is correctly conveyed on the center Lc of the conveyance line 20, and FIG. 3 is a diagram in which a stable period is extracted. It is. As shown in FIG. 2, the signal level of the received light signal rises, stabilizes for a certain period, and then decreases (change period 1 → stable period → change period 2). This is because the moving workpiece W is measured, and the variable period 1, the stable period, and the variable period 2 correspond to the states (a), (b), and (c) in FIG. 2, respectively.

  That is, when the workpiece W is in the measurement area, the light emitted from the light projecting unit 31 is irradiated on the substantially central portion of the side surface P of the workpiece W, so that the level of the received light signal is also stabilized. On the other hand, in a state before the work W is accommodated in the measurement area (state (a) shown in the figure) and a state where the work W is being retreated from the measurement area (state (c) shown in the figure). Since a part of the light emitted from the light projecting unit 31 is applied to the corner portion of the workpiece W, the light irradiation area on the side surface P is not constant, and the level of the light reception signal also changes accordingly. . The stable period corresponds to the stable state of the detection signal of the present invention, and the fluctuation period corresponds to the unstable state of the detection signal.

  Then, the light reception signal described above is input to the data processing unit 40. The data processing unit 40 includes a sampling processing unit (corresponding to sampling means of the present invention) 41, a first data processing unit (corresponding to measuring means of the present invention) 45, and a second data processing unit (corresponding to discriminating means of the present invention). Equivalent) 47.

  The sampling processing unit 41 samples the light reception signal Cn output at a timing synchronized with the light projection timing of the light projection unit 31 from the light reception signals output from the light reception unit 33. In this way, by extracting only the light reception signal Cn synchronized with the light projection timing, even if disturbance light enters the light receiving unit 33 during measurement, the influence can be suppressed. The light reception signal Cn extracted by the sampling processing unit 41 corresponds to the sampling data of the present invention.

  Then, the light reception signal Cn extracted regardless of the fluctuation period and the stable period is output from the sampling processing unit 41, and this is input to the first data processing unit 45 and the second data processing unit 47, respectively.

  When a signal is input, the first data processing unit 45 performs a process of calculating an average value of the light reception signal Cn for each predetermined measurement cycle (corresponding to a predetermined period of the present invention) T. More specifically, the measurement cycle T is set in advance so as to have a time width in which eight light reception signals Cn are extracted by the sampling processing unit 41.

  Therefore, as shown in FIG. 3, eight received light signals Cn are input from the sampling processing unit 41 to the first data processing unit 45 for each measurement period T. As a result, the first data processing unit 45 performs an operation on all eight received light signals Cn input within the measurement period T, and calculates an average value of the signal levels. Then, the calculated average value is output to the output circuit 51 as a measured value. Note that the output of the measurement value from the first data processing unit 45 to the output circuit 51 is random regardless of the fluctuation period or the stable period.

  Next, the second data processing unit 47 is synchronized with the first data processing unit 41, and each measurement cycle T in which the first data processing unit 45 calculates a measurement value is a variable period, Determine the type of stable period. If it is determined that the period is a fluctuation period, the measurement value of the same measurement period T is not output from the output circuit 51 to the outside. That is, the output is controlled through the output circuit control unit 55 so as to stop the output. It should be noted that the measurement value measured in the fluctuation period is not output from the output circuit 51 to the outside so that “the output means performs a preset output corresponding to the unstable state” of the present invention. One embodiment is embodied.

  Hereinafter, a series of processes for discriminating between the stable period and the variable period for each measurement period T will be described with reference to FIGS. 4 and 5. Here, the measurement period Ta will be described as an example. 4 is a flowchart showing the flow of processing executed in the second data processing unit 47, and FIG. 5 is an enlarged view of a portion of the received light signal that shifts from the fluctuation period to the stable period.

  First, in step 10, the counter value M is set to 1 and then the process proceeds to step 20. In step 20, a standby state is waited for the input of the light reception signal Cn from the sampling processing unit 41.

  When the light receiving signal is sampled and the light receiving signal Cn is input from the sampling processing unit 41, the process proceeds to step 30. In step 30, a process of storing the received light reception signal Cn (here, C 1) in the memory 57 is performed by the second data processing unit 47, and then the process proceeds to step 40.

  In step 40, whether or not the counter value M is 4 is determined by the second data processing unit 47. Here, since the value M of the counter is 1, No is determined, and the process proceeds to Step 70. In step 70, the second data processing unit 47 performs a process for determining whether or not the counter value M is 8 or more again. Here, since the value of the counter is 1, as a result of No determination, the routine proceeds to step 80. In step 80, processing for updating the value M of the counter is performed. That is, since the value M of the original counter is 1, it is updated to 2.

  When the value M of the counter is updated, the process proceeds to step 20 again to enter a standby state waiting for the input of the light reception signal Cn from the sampling processing unit 41.

  Thereafter, when sampling is performed by the sampling processing unit 41 and the received light reception signal Cn is input, it is stored in the memory 57, and then the process of updating the value M of the counter is repeated (steps 40 and 70). In both cases, the process of determining No is repeated).

  When the value M of the counter becomes 4, as a result of the Yes determination in Step 40, the process proceeds to Step 50. In step 50, the second data processing unit 47 executes a process of reading the light reception signals C1 to C4 from the memory 57, and the second data processing unit 47 sets the signal level of the read light reception signals C1 to C4. Processing for calculating the average value X1 is performed (average value calculation 1). By this average value calculation 1, as shown in FIG. 5, the average level of the light reception signal C is calculated for the first half of the measurement period Ta.

  When the average value calculation 1 is completed, the process proceeds to step 60. In step 60, the calculated average value X1 is stored in the memory 57, and then the process proceeds to step 70. In step 70, the determination is again made on the value M of the counter. Here, since the value M of the counter is 4, No is determined in Step 70 and the process proceeds to Step 80. In step 80, the value M of the counter is updated from 4 to 5, and thereafter, the process proceeds to step 20 to wait for an input from the sampling processing unit 41.

  In the subsequent processing, when the light receiving signal Cn is input from the sampling processing unit 41, the received light signal Cn is stored in the memory 57, and then the process of updating the counter value M is repeatedly performed. When the value M of the counter reaches 8, as a result of the Yes determination in Step 70, the process proceeds to Step 90.

In step 90, the process of reading the light reception signals C5 to C8 from the memory 57 is executed by the second data processing unit 47, and the second data processing unit 47 sets the signal level of the read light reception signals C5 to C8. Processing for calculating the average value X2 is performed (average value calculation 2). By this average value calculation 2, the average level of the received light signal C is calculated for the latter half of the measurement cycle Ta (see FIG. 5).
The processing function performed by the average value calculation function unit of the present invention is realized by the processing executed in step 50 and step 90.

  When the average value calculation 2 is completed, the process proceeds to step 100 thereafter. In step 100, the second data processing unit 47 performs processing for reading the average value X1 calculated in the previous step 50 from the memory 57, and the read average value X1 and the average calculated in step 90. After the value X2 is compared in magnitude, the process of subtracting the average value on the smaller side from the average value on the larger side and calculating the difference Z (corresponding to the amount of change in the sampling signal of the present invention) is the second data processing. This is performed by the unit 47. The processing function performed by the arithmetic function unit of the present invention is realized by the processing executed in step 100.

  Thereafter, in step 110, the second data processing unit 47 performs a process of comparing the threshold value Y (corresponding to a predetermined level of the present invention) Y and the difference Z between the average values X1 and X2 calculated in step 110. Here, the threshold value Y is set to a value such that the amount of change in the level of the received light signal does not exceed that if the measurement is performed normally. For example, the maximum variation of the light reception signal Cn obtained as a result of the preliminary test performed with the workpiece W stationary is set.

  On the other hand, as described above, the average value X1 is the average level of the signal in the first half portion of the measurement period T, whereas the average value X2 is the average level of the signal in the second half portion. In the Ta period, the difference Z between the average values X1a and X2a is large, and the value exceeds the threshold Y. As a result, it is determined as Yes in Step 110 (that is, it is determined that the signal level is an unstable fluctuation period), and the process proceeds to Step 120. Note that the processing performed by the determination function unit of the present invention is realized by the determination processing in step 110.

  In step 120, the determination signal Sa is output from the second data processing unit 47 to the output circuit control unit 55. When the determination signal Sa is input, the output circuit control unit 55 outputs an output stop signal Sb to the output circuit 51 (see FIG. 1). Thereby, in the measurement period Ta in the fluctuation period, the measurement value is input from the first data processing unit 45 to the output circuit 51, but this is not output to the outside as the measurement result (stop of output). . As a specific configuration for stopping the output of the output circuit 51, for example, the output line of the output circuit 51 may be opened by the output circuit control unit 55.

  Thereafter, the process proceeds to step 130, and after the counter value M is reset, the process proceeds to step 10 again. As a result, the series of processing from step 20 to step 130 described above is performed for the next measurement cycle Tb, and processing for determining the amount of change in the signal level of the light reception signal Cn for the measurement cycle Tb, that is, the measurement cycle Tb. Average values X1 and X2 are calculated for the first half and the second half, respectively (step 100). Thereafter, a process for comparing the difference Z between the threshold value Y and the average values X1 and X2 is performed (step 110). Also in this case, the difference Z is larger than the threshold value Y, and as a result, it is determined that the period is a fluctuation period.

  Thereafter, the measurement period Tc is followed by the measurement period Tc. The measurement period Tc is in a stable period, and both average values X1c and X2c are substantially equal as shown in FIG. Therefore, No is determined in step 110. As a result, the process skips step 120 and proceeds to step 130, so that the output regulation of the output circuit 51 by the second data processing unit 47 and the output circuit control unit 55 does not work.

  Therefore, the output circuit 51 outputs according to the measurement result. For example, the measurement signal Sr is output to an external device in order to display the measurement result on a monitor (not shown). As a result, display control of the monitor is performed through the external device that has received the measurement signal Sr, and the measurement value is displayed. As a result, based on the magnitude of the displayed measurement value, the operator can know whether or not the workpiece W is correctly conveyed in the center of the conveyance line 20.

That is, when the workpiece W is conveyed at the end of the line (when it is displaced in the + direction in FIG. 3), since the distance D shown in FIG. 3 is shortened, the signal level of the light reception signal Cn is increased. The level of the measurement value output through the output circuit 51 increases.
On the other hand, when the workpiece W is transported on the line in a state shifted to the opposite side (in the case of being shifted in the-direction in FIG. 3), the distance D becomes longer, resulting in the signal level of the light reception signal Cn. Becomes lower. Therefore, at this time, the level of the measurement value output through the output circuit 51 is lowered. In this way, it is possible to know the positional deviation of the workpiece W on the transfer line 20 from the level of the measured value in the stable period.

  According to this embodiment, the second data processing unit 47 is provided in the data processing unit 40 to monitor the transition of the signal level of the light reception signal Cn. That is, for each measurement period T, the magnitude of the change amount of the signal level was calculated. Then, the variation period and the stable period are discriminated based on the magnitude of the change amount, and the measurement result is output from the output circuit 51 only in the stable period when a highly reliable measurement result is obtained. With such a configuration, it is possible to measure a moving object with a relatively simple configuration (the position detection sensor 5 described in the conventional example can be eliminated).

  Further, in the present embodiment, with respect to the measurement period T, the average value of the signal levels of the light reception signal Cn in the first half part and the second half part is calculated, and the difference between the two average values is used as the signal level change amount. With such a configuration, it is possible to suppress the error compared to the case where the amount of change is simply determined based on the signal level difference, that is, even if there is an abnormal value in the data due to the influence of noise, This is because it is averaged.

<Embodiment 2>
Next, Embodiment 2 of the present invention will be described with reference to FIG.
The second embodiment is obtained by partially changing the configuration of the data processing unit 40 with respect to the configuration of the first embodiment. The other components are the same as those of the first embodiment, and thus the same components are denoted by the same reference numerals. The description is omitted.

  In the first embodiment, the second data processing unit 47 monitors the transition of the signal level of the light reception signal Cn, and discriminates between the fluctuation period and the stable period based on the amount of change in the signal level. In the fluctuation period, the output stop signal Sb is output to the output circuit 51 through the output circuit control unit 55, and the output operation of the output circuit 51 is stopped.

  In the second embodiment, the second data processing unit 47 monitors the signal level transition of the light reception signal Cn and distinguishes between the fluctuation period and the stable period based on the change amount of the signal level. The subsequent processing has been changed. That is, in the second embodiment, a notification unit 65 is provided instead of the output circuit control unit 55 of the first embodiment, and a predetermined notification operation is performed in advance. The notification means 65 is, for example, an indicator lamp, a buzzer, etc., and the predetermined notification operation is blinking if the indicator lamp is used, and if the buzzer is used, a warning sound is sounded several times. When the second data processing unit 47 determines that the period is a fluctuation period and the determination signal Sa is input, the predetermined notification operation is performed by the notification unit 65. This makes it possible for the operator to be informed during the fluctuation period when the signal level is unstable.

<Embodiment 3>
Next, Embodiment 3 of the present invention will be described with reference to FIGS. In the first embodiment, the amount of change in the light reception signal Cn is calculated based on the average value. That is, in average value calculation 1, the average value X1 is obtained for the first half received light signals C1 to C4 in the measurement period T, and in average value calculation 2, the second half received light signals C5 to C8 in the measurement period T An average value X2 was determined. The difference Z between the two average values X1 and X2 is used as the amount of change in the light reception signal Cn. In the third embodiment, the average value calculation is not performed, and the light reception signal Cn is calculated based on the level of the light reception signal Cn. The amount of change in Cn is obtained.

  Specifically, the second data processing unit 67 sequentially performs the following extraction processing (corresponding to the processing content performed by the extraction function unit of the present invention) and arithmetic processing (corresponding to the processing content performed by the calculation function of the present invention) in order. After that, determination processing (corresponding to the processing content performed by the determination function unit of the present invention) is performed.

Hereinafter, the Ta period shown in FIG. 8 will be described as an example.
(1) Extraction Processing The second data processing unit 67 compares the signal levels of the eight light receiving signals Cn C1 to C8. Then, the signal with the minimum signal level (here, C1) and the signal with the maximum signal level (here, C8) are extracted.
(2) Arithmetic processing The second data processing unit 67 performs a subtraction process on the signal levels of both the received light signals C1 and C8 extracted in the extraction processing to calculate a level difference Z ′. That is, Z ′ = H8−H1, and this is the amount of change in the light reception signal Cn.
(3) Discrimination process The second data processing unit 67 performs a process of comparing the difference Z ′ and the threshold Y ′ following the calculation process, and whether or not the difference Z ′ exceeds the threshold Y ′. Determine.

  Thus, if the amount of change is calculated only by comparing the signal level and the simple subtraction process, the processing load of the second data processing unit 47 can be greatly reduced, and the processing speed of the sensor can be increased. Contribute.

<Other embodiments>
The present invention is not limited to the embodiments described with reference to the above description and drawings. For example, the following embodiments are also included in the technical scope of the present invention.

  (1) In the first to third embodiments, a photoelectric sensor that detects the position / displacement of a workpiece by using light projection / light reception is taken as an example of the detection sensor. Any sensor can be used as long as it detects a sensor such as a magnetic proximity sensor and an ultrasonic sensor.

  (2) In the first to third embodiments, the example of detecting the position of the workpiece W flowing on the transport line is illustrated as an example of measurement. However, the application is not limited to this. For example, on the transport line What detects the difference in the color of the flowing workpiece | work W etc. may be sufficient.

  (3) In the first to third embodiments, the average value of the eight light reception signals Cn is the measurement value. However, the measurement value is not limited to the average value, and a specific light reception signal Cn is extracted, The signal level may be a measured value.

  (3) In the first embodiment, the measurement cycle T is divided into two sections, the first half and the second half, and the average value of the signal level of the light reception signal Cn is calculated for each period, and the difference between them is used as the signal level change amount. However, the calculation method of the amount of change is not limited to this, and various methods can be applied. For example, the measurement period is equally divided into three or more sections, and an average value is calculated for each of the divided sections. Then, the maximum value and the minimum value are extracted from the average value, and the difference is used as the change amount.

1 is a block diagram showing an electrical configuration of a photoelectric sensor applied to Embodiment 1. FIG. The figure which shows transition of the light reception signal which is output from the light receiving section Similarly, the figure which shows transition of the light reception signal which is output from the light receiving section Flowchart diagram showing the flow of processing executed by the second data processing unit An enlarged view of the transition from the fluctuation period to the stable period The block diagram which shows the electrical constitution of the photoelectric sensor applied to Embodiment 2. FIG. The block diagram which shows the electrical constitution of the photoelectric sensor applied to Embodiment 3. The figure which shows transition of the light reception signal Cn in Embodiment 3. FIG. Figure showing a conventional example Figure showing a conventional example

Explanation of symbols

30 ... Photoelectric sensor (detection sensor)
31 ... Projection unit (physical quantity detection means)
33. Light receiving part (physical quantity detection means)
40: Data processing unit 41 ... Sampling processing unit (sampling means)
45 ... First data processing unit (measuring means)
47. Second data processing unit (discriminating means)
51. Output circuit (output means)
55. Output circuit control section (output control means)

Claims (5)

A physical quantity detection means for performing a detection operation on the detected object and outputting a detection signal corresponding to the level of the physical quantity obtained as a result;
Sampling means for obtaining the sampling data by sampling the detection signal output from the physical quantity detection means at every predetermined timing;
Measurement means for measuring a measurement value as a detection result by the physical quantity detection means based on a plurality of the sampling data obtained from the sampling means within a predetermined period;
Output means for outputting according to the measurement value measured by the measurement means, and a detection sensor comprising:
For the sampling data output from the sampling means, the amount of change in the sampling data within the predetermined period is compared with a predetermined level to determine whether the detection signal is in a stable state or an unstable state, and according to the determination result Discrimination means for outputting a discrimination signal;
A determination signal output from the determination means is input, and when the determination result is in an unstable state, a preset output corresponding to the unstable state is performed to the output means. And an output control means. A physical quantity detection means for performing a detection operation on the detected object and outputting a detection signal corresponding to the level of the physical quantity obtained as a result;
Sampling means for obtaining the sampling data by sampling the detection signal output from the physical quantity detection means at every predetermined timing;
Measurement means for measuring a measurement value as a detection result by the physical quantity detection means based on a plurality of the sampling data obtained from the sampling means within a predetermined period;
An output means for outputting according to the measurement value measured by the measurement means, a detection sensor comprising:
For the sampling data output from the sampling means, it is determined whether the detection signal is in a stable state or an unstable state based on a comparison between a change amount of the sampling data within the predetermined period and a predetermined level, and the determination result A discrimination means for outputting a corresponding discrimination signal;
A notification unit configured to receive a determination signal output from the determination unit, and performing a predetermined notification operation corresponding to the unstable state when the determination result is an unstable state; A detection sensor comprising: The determination means includes an extraction function unit that extracts a maximum value and a minimum value from a plurality of sampling data within the predetermined period, and
An arithmetic function unit for calculating a difference between the extracted maximum value and the minimum value;
A determination function unit configured to determine whether the detection signal is in a stable state or an unstable state by comparing a difference as the amount of change calculated by the calculation function unit with the predetermined level, and determining according to a determination result The detection sensor according to claim 1 or 2, wherein a signal is output. The determination means includes, for each divided period obtained by equally dividing the predetermined period so that at least two or more sampling data is acquired, an average value calculation function unit that calculates an average value of the sampling data within the divided period; ,
When the divided period is obtained by dividing the predetermined period into two, the difference between the two average values calculated by the average value calculating means is calculated,
In the case where the divided period is obtained by dividing the period into three or more, the one having the maximum value and the minimum value is extracted from the three or more average values calculated by the average value calculating means, A calculation function unit for calculating the difference;
A determination function unit configured to determine whether the detection signal is in a stable state or an unstable state by comparing a difference as the amount of change calculated by the calculation function unit with the predetermined level, and determining according to a determination result The detection sensor according to claim 1 or 2, wherein a signal is output. 5. The detection sensor according to claim 1, wherein the measurement unit calculates an average value from the sampling data within the predetermined period and uses the average value as the measurement value. 6.

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