JP5152397B1 - PHOTOELECTRIC SENSOR AND METHOD FOR SUPPORTING WORK CHECKING LIGHT EMITTING STATUS OF PHOTOELECTRIC SENSOR - Google Patents

Abstract

Information suitable for determining a threshold value suitable for detection is displayed.
The light projecting unit 103 and the light receiving unit 104 determine whether the light incident state or the non-light incident state by comparing the amount of received light obtained by the light receiving process with a preset threshold value. In the photoelectric sensor including the control unit 105 that functions as a detection unit that outputs the determination result and the display unit 100 that can display the received light amount, the photoelectric sensor is determined based on the currently set threshold value. For a plurality of light receiving periods and a plurality of light receiving periods, a light receiving amount in a period in which the light receiving amount is relatively lowest in each light receiving period and a light receiving amount in each light receiving period are relatively The received light amount in the highest period is specified, and the two specified representative received light amounts are displayed on the display unit 100.
[Selection] Figure 4

Description

  The present invention projects light for detection, receives the projected light or reflected light for the projected light, and detects an object by comparing the amount of received light with a predetermined threshold value. The present invention relates to a photoelectric sensor.

  In the amount of light received by the photoelectric sensor that detects a moving object, a portion that changes in a mountain shape exceeding a set threshold value and a portion that changes in a valley shape from below the threshold value are alternately generated (hereinafter referred to as the following). , Each fluctuation part is called "mountain" "valley"). The transmission type sensor outputs a detection signal indicating “object present” when a change from a mountain to a valley occurs. On the other hand, the reflection type sensor outputs a detection signal indicating “there is an object” when the change from the valley to the mountain occurs.

  Regardless of the type of sensor, to ensure the accuracy of detection, adjust the sensitivity so that there is a sufficient difference between the peaks and valleys, and adjust both the peak value of the peaks and the bottom value of the valleys. Therefore, it is necessary to set a threshold value with a margin. In addition, it is necessary to be able to confirm the actual light reception state to help the user manually set the threshold and to check whether the threshold suitable for detection is set. is there.

  In view of the above necessity, there is a photoelectric sensor having a function of extracting the maximum value and the minimum value of the amount of received light in a period of a certain length and displaying each extracted value (see Patent Document 1). ).

Japanese Patent No. 4023621

  In a photoelectric sensor, a small object or an object that moves at high speed is often used as a detection target, and a plurality of types of objects may be the detection target, so the reflection state (reflectance, reflection direction) depends on the detection target object. Etc.) may fluctuate. If the fluctuation of the reflection state is large, the variation of the received light peaks and troughs also increases.

  According to the invention described in Patent Document 1, the peak value of the peak having the largest amplitude among the peaks included in the period of a certain length and the peak value of the valley having the largest amplitude among the valleys included in the same period. Since the bottom value is extracted and displayed, a value having a sufficient margin for these values is set as the threshold value. For this reason, if there is a large variation in the peaks and valleys of the amount of received light, the margin with respect to the threshold is small in the peaks and valleys with small amplitudes, and the detection operation may become unstable.

  The present invention has been made paying attention to the above problem, and an object thereof is to display information suitable for determining a threshold suitable for detection.

The photoelectric sensor to which the present invention is applied includes a light projecting unit that projects light for detection, a light receiving unit that performs light reception processing according to the light projecting operation and outputs received light amount data, and light reception from the light receiving unit. The process of acquiring the amount data and the process of determining whether the light incident state or the non-light incident state by comparing the received light amount indicated by the acquired received light amount data with a threshold value are repeated. A detection means for switching the output indicating the discrimination result on condition that the received light amount data for obtaining the same discrimination result as after switching is acquired P times (P ≧ 2) when the result is switched ; Furthermore, the following first and second representative received light amount specifying means and output means are provided.

First representative light amount specifying means, the light incident period received light amount data indicating the amount of received light is judged that receiving light by the threshold that is currently set is obtained P or more as a plurality subject, the subject input For each light period, the minimum value among the light reception amounts indicated by the P light reception amount data acquired during that period is specified as the representative light reception amount in the light incident period, and no light is incident according to the currently set threshold value. For a plurality of non-light incident periods in which P or more received light quantity data indicating the amount of received light that is determined to be in a state are obtained , light reception indicated by P received light quantity data acquired during each target non-light incident period The maximum value among the amounts is specified as the representative received light amount in the non-light incident period.
The second representative received light amount specifying means specifies a minimum value among the representative received light amounts specified by the first representative received light amount specifying means for each of the plurality of light incident periods as a representative received light amount representing a light incident state, The maximum value among the representative received light amounts specified by the first representative received light amount specifying means for each of the plurality of non-incident periods is specified as the representative received light amount representing the non-incident state.
The output means outputs information indicating the two representative received light amounts specified by the second representative received light amount specifying means for displaying each representative received light amount. In the display process performed in accordance with this output, for example, the representative received light amounts can be displayed side by side, or both can be alternately displayed according to the switching operation.

In the above, the light incident period corresponds to a period in which a peak of received light amount occurs, and the non-light incident period corresponds to a period in which a valley of received light amount occurs. Even if the light incident state and the non-light incident state are switched, the output is not switched immediately, but the sensor that inverts the output after the state after the switching continues P times, If the threshold value is not set so that P received light amounts can be secured, erroneous detection occurs. Even when P received light amounts are obtained, it is difficult to perform stable detection with respect to variations in the received light amount if the margin of the received light amount with respect to the threshold is small.
In consideration of the above-described problems, the present invention specifies the minimum value among the P received light amounts included in the peak of the received light amount as the representative received light amount, and the valley of the received light amount in the valley. the maximum value of P number of light receiving quantity contained identified as the representative light receiving quantity, the least value is less representative light receiving quantity in the plurality of peaks as the representative light receiving quantity representing the light incident state, among the plurality of valleys The representative received light amount having the highest value is displayed as the representative received light amount indicating the non-light incident state. Since the peak and the valley are distinguished based on the currently set threshold value, the user is based on the relationship between the two representative received light amounts displayed (such as the difference between the representative received light amounts) A threshold value suitable for detection can be determined.

Note that the threshold value for dividing the light incident period and the non-light incident period to be processed by the representative received light amount specifying unit is not limited to the threshold value set for the determination process of the detection unit, but the determination process. It may be a threshold value temporarily set as a candidate value for changing the threshold value for.
The first representative received light amount specifying means according to the first embodiment of the photoelectric sensor described above receives, for each of a plurality of light incident periods, the light received quantities indicated by the received light quantity data acquired in the light incident periods in descending order of size. When arranged, the Pth received light amount is specified as the representative received light amount in the light incident period, and the received light amount indicated by the received light amount data acquired in the non-light incident period is determined for each of the plurality of light incident periods. The P-th received light amount when arranged in ascending order of size is specified as the representative received light amount in the non-light incident period. According to this embodiment, since the minimum value in the P-th highest received light amount of each peak and the maximum value in the P-th lowest received light amount of each valley are displayed, the user can set both values. Therefore, it is possible to easily determine a threshold value suitable for detection processing.

In the second embodiment of the photoelectric sensor described above, the second representative received light amount specifying means includes the first representative received light amount specifying means for each of a plurality of light incident periods occurring within a predetermined time. The minimum value among the identified representative received light amounts is specified as the representative received light amount representing the incident light state. Also identified as the representative light receiving quantity representing the non-light incidence state the maximum value among the representative light receiving quantity is first representative light receiving quantity specifying means specified for each of a plurality of non-light incident period occurring within a predetermined time .
According to this embodiment, for example, the time required for a sufficient number of objects to pass through is determined based on the moving speed of the detection object, and this time is set as the processing time by the representative received light amount specifying means. It is possible to obtain peaks and valleys of received light amounts that vary in various values, and to display the representative received light amounts of peaks and valleys having the smallest margin with respect to the threshold value obtained by dividing the peaks and valleys.

In the photoelectric sensor according to the third embodiment, the first representative light reception amount specifying means switches the light reception period and the non-light reception period by comparing the light reception amount indicated by the light reception amount data from the light receiving unit with a threshold value. And determining the representative amount of received light in each period. Second representative light amount specifying means, each time the switch from the light incident period to the non-light incident period occurs, first representative light receiving quantity specified for a plurality of past light incident period dating back from the light incident period immediately before The minimum value of the representative received light quantity specified by the means is specified as the representative received light quantity that represents the incident light state, and every time a transition from the non-light incident period to the light incident period occurs , the past goes back from the previous non-light incident period. The maximum value among the representative received light amounts specified by the first representative received light amount specifying means for the plurality of non-incidence periods is specified as the representative received light amount representing the non-incident state . According to this embodiment, for example, by acquiring the amount of light received while a plurality of objects are moving and performing processing, the threshold is finally determined from the mountains and valleys corresponding to each object. can margin against the value to display the representative light receiving quantity of the smallest peaks and valleys.

The photoelectric sensor according to the fourth embodiment further accepts an operation of selecting one of a plurality of detection modes having different values of P, and sets the value of P according to the selected detection mode in the detection means. Setting means is provided.

In the photoelectric sensor according to the fifth embodiment, the output unit includes a display unit for displaying the two representative received light amounts specified by the second representative received light amount specifying unit. That is, the detection sensor itself has a function of displaying two types of representative received light amounts.
Even when the output means does not include a display unit, information indicating each representative received light amount can be given to an external display device for display.

The photoelectric sensor according to the sixth embodiment includes an operation unit for performing an operation of changing a threshold value, and detection means in conjunction with display of two representative received light amounts specified by the second representative received light amount specifying means. The threshold value is output so that the threshold value set for the discrimination process is displayed, and the threshold value is set according to the operation by the operation unit under the display state by this output. And a threshold value changing means for changing. According to this configuration, for example, the current threshold value is displayed in response to an operation for calling the threshold value for each representative received light amount display, and the user can display the threshold value and the representative received light amount. When it is determined that the relationship with is not appropriate, the threshold value can be changed by an operation.

  The display of the threshold value may be switched to the display of the representative received light amount, or a method of adding the threshold value display to the display of the representative received light amount may be used. In addition, each representative light reception amount and threshold value may be displayed from the beginning in a manner that allows comparison between the three without performing a threshold value calling operation by the user.

The present invention can be applied to a method for supporting the work of confirming the light receiving state of a photoelectric sensor. In this way, the light incident period received light amount data indicating the amount of received light is determined from the threshold to the photoelectric sensor is currently set to light incident state is obtained P or more as a plurality interest, each light incident period of interest The minimum value of the received light amount indicated by the P received light amount data acquired during that period is specified as the representative received light amount in the light incident period, and is determined as a non-light incident state based on the currently set threshold value. the non light incident period received light amount data are obtained P or more indicating the received light amount of a plurality of objects, in the obtained P number of received light amount data indicating received light amount during that period for each non-light incident period of interest Is specified as the representative received light amount in the non-light-incidence period. Further, the minimum value of the representative received light amounts in each of the plurality of light incident periods is specified and displayed as the representative received light amount representing the light incident state, and the maximum of the representative received light amounts in each of the plurality of non-light incident periods is displayed. The value is specified and displayed as a representative received light amount representing a non-light incident state .

  The above method can be implemented by the control unit of the photoelectric sensor, but is not limited to this. The amount of received light acquired from the light receiving unit of the photoelectric sensor is transmitted to an external device, and the representative amount of received light is specified or displayed by the external device. May be performed. Alternatively, the process of specifying the representative received light amount may be performed by a photoelectric sensor, and the specified representative received light amount may be transmitted to an external device to display the representative received light amount outside the sensor.

  According to the present invention, even when the variation in the amount of received light varies depending on the object to be detected, the representative amount of received light in the period with the smallest margin with respect to the threshold value is displayed for each of the light incident period and the non-light incident period. Therefore, the user can determine that the received light amount that provides a sufficient margin for both representative received light amounts is an appropriate value of the threshold value. Therefore, when the current threshold value is far from the appropriate value, stable detection processing can be performed by changing the threshold value.

It is a perspective view which shows the external appearance of an optical fiber type photoelectric sensor. It is a perspective view which shows the state which opened the upper surface cover of the photoelectric sensor of FIG. It is the figure which looked at the upper surface containing the operation part and display part of the said photoelectric sensor from the front. It is a block diagram which shows the electric constitution of the said photoelectric sensor. It is a figure which shows the example of the display expand | deployed on a display part, when performing the process which changes a threshold value with reference to the peak value and bottom value of light reception amount. It is a table which shows the pulse count number used for a detection process according to mode. It is a figure which shows the specific example of the detection process of a pulse count system with the problem. It is a flowchart which shows the procedure regarding the process which displays the peak value and bottom value of received light quantity. It is a flowchart which shows the detailed procedure of the process at the time of incident light, and the process at the time of non-incident light. It is a table which shows the example of the change of the value of the buffer which stores the light reception amount in a light-incidence period. It is a flowchart which shows the 2nd example of the procedure regarding the process which displays the peak value and bottom value of light reception amount. It is a flowchart which shows the 3rd example of the procedure regarding the process which displays the peak value and bottom value of light reception amount.

1 and 2 show the appearance of an optical fiber photoelectric sensor to which the present invention is applied.
The photoelectric sensor 1 includes a main body 10 and a pair of optical fibers 11 and 12 attached to the front surface of the main body 10. The optical fiber 11 is for light projection, and the other optical fiber 12 is for light reception. Head portions 11A and 12A each including a lens or the like are attached to the tip portions of the optical fibers 11 and 12, respectively. The actual optical fibers 11 and 12 can be longer than the illustrated state.

  The optical fibers 11 and 12 are inserted into the insertion ports 11B and 12B on the front surface of the main body 10, respectively. A light projecting portion is provided in the vicinity of the insertion port 11B of the light projecting optical fiber 11, and a light receiving unit is provided in the vicinity of the insertion port 12B of the light receiving optical fiber 12. A connection cable 14 is drawn from the back surface of the main body 10.

  The photoelectric sensor 1 functions as a transmissive sensor that receives light projected from the light projecting unit by the light receiving unit and discriminates that the optical path is shielded from being “object present”. It can also function as a reflective photoelectric sensor that receives reflected light and discriminates that there is an object. When used as a reflective photoelectric sensor, a common head portion is attached to the tip of each of the optical fibers 11 and 12, and this head portion is arranged toward the detection area.

  The received light amount data generated by the light receiving unit is input to the control unit (CPU), and it is determined whether it is in the light incident state by comparison with a threshold value registered in advance, and the determination result is output. The

  A display unit 100 and a plurality of push button switches SW <b> 1 to SW <b> 5 are provided on the upper surface of the main body unit 10. The cover 13 is put on the upper surface when in use, but the cover 13 is opened at the time of setting or the like, and the operation of the pushbutton switches SW1 to SW5 becomes possible. FIG. 2 is a perspective view of the main body 10 with the cover 13 opened, and FIG. 3 is a front view of the upper surface. Since the cover 13 is transparent, the display on the display unit 100 can be confirmed via the cover 13 even when the cover 13 is attached.

The configuration of the upper surface will be described with reference to FIGS.
In this embodiment, a push button switch SW1 is provided at a position closer to the front surface of the main body, a display unit 100 is provided behind the push button switch SW1, and four push button switches SW2, SW3, SW4 are provided behind the display unit 100. , SW5 is deployed. In addition, although the button part of pushbutton switch SW2, SW3 is united, the switch main body (not shown) in the housing | casing 10 is each independent.

  The display unit 100 is provided with a pair of indicators 101 and 102 and five indicator lights 111 to 115. The display devices 101 and 102 are a combination of four 7-segment LEDs, and display numbers and alphabetic character strings of up to 4 digits, respectively.

Since the front pushbutton switch SW1 is used for a tuning process to be described later, the switch SW1 is hereinafter referred to as “tuning switch SW1”.
A pair of push button switches SW2 and SW3 on the rear side of the display unit 100 are used to change numerical values and submenus displayed on the display devices 101 and 102. Hereinafter, the switch SW2 with the + mark on the button portion is referred to as “up switch SW2”, and the switch SW3 with the − mark on the button portion is referred to as “down switch SW3”.

The push button switch SW4 is used for switching between the measurement mode and the setting mode, and for selecting and determining the main menu of the setting mode. Hereinafter, this switch SW4 is referred to as “mode switch SW4”.
When any setting is made in the setting mode, the set content is confirmed. When the mode is switched to the measurement mode by the mode switch SW4, the measurement is started with the set contents.

  The push button switch SW5 is for switching the output format of the sensor 1. Specifically, the “light on mode” that turns the output on when the amount of received light exceeds a threshold value or the “dark on” state that turns the output on when the amount of received light falls below the threshold value. Mode "is selected.

The indicator lamp 111 is lit when the detection signal from the sensor 1 is turned on in the detection process. The indicator lamp 112 is lit when the light-on mode is selected, and the indicator lamp 113 is lit when the dark-on mode is selected.
The indicator lamp 114 is lit when the process for automatically adjusting the amount of received light on the display is set to be effective. The indicator lamp 115 is lit while the tuning process is being performed and after the end of tuning.

FIG. 4 shows the electrical configuration of the photoelectric sensor 1.
In this sensor 1, in addition to the light projecting unit 103 and the light receiving unit 104, a memory 106 storing a program, a display unit 100, an operation unit 110, an external device interface 107, an output unit 108, a power source, in addition to the light projecting unit 103 and the light receiving unit 104 The unit 109 and the like are connected.

  The display unit 100 includes the above-described indicators 101 and 102 and indicator lamps 111 to 115, and the operation unit 110 includes push button switches SW1 to SW5. The light projecting unit 103 includes an LED 131 and an LED drive circuit 132, and the light receiving unit 104 includes an amplifying circuit 142 and an A / D conversion circuit 143 in addition to a photodiode (PD) 141. In the light projecting unit 103, a driving current flows from the LED drive circuit 132 to the LED 131, and a light projecting process is performed. In the light receiving unit 104, the output from the photodiode 141 is processed by the amplification circuit 142 and the A / D conversion circuit 143, thereby generating digital data representing the amount of received light (hereinafter referred to as “light reception amount data”). .

  The CPU 105 inputs the received light amount data from the light receiving unit 104 and executes detection processing while controlling the operations of the light projecting unit 103 and the light receiving unit 104 according to the program stored in the memory 106. The detection result is output via the output unit 108 and the external device interface 107.

  When the tuning switch SW1 is operated in the measurement mode, a setting process called “tuning” is performed. In the tuning, threshold setting processing and sensitivity adjustment processing, which are indispensable settings for detection processing, are performed collectively. Briefly, when a moving workpiece is to be detected, the tuning switch SW1 is continuously pressed for a predetermined time or more while moving the workpiece under the same conditions as at the time of detection. Specify the minimum value. Then, the sensitivity is adjusted so that the maximum value becomes a predetermined target value, the minimum value is corrected in accordance with this adjustment, and an intermediate value between the maximum value and the minimum value is set as a threshold value. The sensitivity is adjusted by adjusting the drive current flowing through the light projecting unit 103 and the magnification of the amplifier circuit 142 of the light receiving unit 104.

  In addition, the tuning process may be performed in accordance with an operation of pressing the tuning switch SW1 twice at a relatively short interval. In this case, one operation is performed in a state where the work is placed in the detection area, and the other operation is performed in a state where the work is not in the detection area. Then, the sensitivity is adjusted so that the higher value of the received light amount captured in accordance with each operation becomes the target value, and the other received light amount is corrected in accordance with this adjustment. Set the intermediate value to the threshold value.

  When the setting mode is selected by the mode switch SW4, a setting menu is displayed on each of the displays 101 and 102 of the display unit 100. The user performs a desired setting while switching the menu display using the up switch SW2 or the down switch SW3.

  The setting mode includes a process of checking the light receiving state of the sensor and manually changing the threshold set by the tuning process as necessary. FIG. 5 shows a display example developed on the display unit 100 for the work of confirming the amount of received light and the work of changing the threshold value.

  First, as shown in FIG. 5A, the user selects and displays a character string “disp” (abbreviation of “display”) as shown in FIG. The character string “Pb” is displayed on the device 102. When the user operates the mode switch SW4 in this display state, as shown in FIG. 5B, the display device 101 enters a state of displaying the character string “PEAK”, and the display device 102 displays “botn (n is A character string “with bar” (which means “BOTTOM”) is displayed.

  Further, when a predetermined time elapses, numerical values as shown in FIG. In this embodiment, a state where a received light amount equal to or greater than the threshold value is set as a light incident state, and a state where a received light amount smaller than the threshold value is set as a non-light incident state, a numerical value displayed on the display 101 ( 3185) is a representative received light amount in a period (light incident period) in which the light incident state continues, and a numerical value (1467) displayed on the display unit 102 is a representative in a period (non light incident period) in which the non-light incident state continues. This is the amount of light received.

  The display in FIG. 5C and the display in FIG. 5B are alternately switched after a predetermined time. Thereby, the representative received light amount displayed on the display device 101 is presented to the user as the peak value of the received light amount, and the representative received light amount displayed on the display device 102 is presented to the user as the bottom value of the received light amount.

  In accordance with this situation, in the following description, the representative received light amount displayed on the display unit 101 is referred to as a peak value, and the representative received light amount displayed on the display unit 102 is referred to as a bottom value. However, as described in detail below, each representative received light amount is not the maximum value or the minimum value of the received light amount.

  When the user operates the up switch SW2 or the down switch SW3 at a predetermined time with respect to the display of the peak value and the bottom value, the display ends, and “th” is displayed on the display 102 as shown in FIG. And a numerical value indicating the current threshold value is displayed on the display unit 101.

  In the above display state, the user can freely change the numerical value of the display 101 as shown in FIG. 5E by operating the up switch SW2 and the down switch SW3. When the mode switch SW4 is operated after this change, the measurement mode is returned to and detection processing using the changed numerical value as a threshold value is started.

  In addition, the display form of the peak value and the bottom value and the display of the threshold value are not limited to the example of FIG. 5, but, for example, three kinds of values are switched one by one together with a character string indicating the meaning of each value. May be displayed. Alternatively, the display unit 100 may be configured by a liquid crystal panel or the like to display three types of values in parallel. In this case, each numerical value may be displayed in a form that visually represents the size, such as a bar graph.

  Next, in the detection process of this embodiment, the amount of received light is sampled according to the clock pulse for control, and the sampled received light amount is compared with a threshold value to determine whether the light incident state or the non-light incident state. The output is controlled while discriminating. However, even if the determination result is switched, the output is not switched immediately, but the output is switched after confirming that the same result as that after the switching is obtained a certain number P times continuously.

  Specifically, when changing from a state where the amount of received light indicating non-incident light (smaller than the threshold) is obtained to a state where the amount of received light indicating incident light (greater than or equal to the threshold) is obtained, the CPU 105 After confirming that the incident light P continues for the first time, the light output is switched from an output indicating non-incident light to an output indicating light incident. Similarly, when changing from a state where the amount of received light indicating the incident light is obtained to a state where the amount of received light indicating the non-incident light is obtained, confirm that the non-incident light continues P times for the first time. Then, the output indicating incident light is switched to the output indicating non-incident light. Therefore, when the time when the light receiving state changes is the first time, the output is switched in accordance with the timing of the P + 1th light receiving.

The detection process by the above method is hereinafter referred to as “pulse count type detection process”.
In the detection process of the pulse count method, the accuracy and speed of detection can be changed by changing the value of P. In this embodiment, four types of detection modes as shown in FIG. 6 are prepared, and any one of them can be selected in the setting mode.

FIG. 7 shows a specific example of the detection process of the pulse count method together with the problem.
In this example, it is assumed that the output format is set to the light-on mode and the fastest mode (P = 2) is selected as the detection mode. FIG. 7 shows a change curve of the amount of received light. On this curve, the sampling points by the CPU 105 are indicated by dots, and each sampling point and a change in output from the sensor are shown in correspondence with each other.

  Assuming that the received light amount curve during the light incident period corresponds to the peak of the received light amount, and the received light amount curve during the non-light incident period corresponds to the trough of the received light amount, the detection processing of the pulse count method without error is set to P = 2 To do so, every mountain and every valley needs to contain two or more sampling points each.

The change curve of the amount of received light in the example of FIG. 7 is generated while two workpieces pass through the detection area, and one peak and valley are generated for each workpiece. Due to the large difference, the amplitudes of the peaks and valleys vary considerably. Also, the amplitude and width of the peaks and valleys vary depending on the set threshold value.
Even when the variation in the amount of received light is large, as shown in FIG. 7A, if the threshold is set in a state where each peak and each valley include two or more sampling points, the workpiece The output can be switched on / off each time. On the other hand, when the threshold value is set to a value lower than that in FIG. 7 (1) as in the example of FIG. 7 (2), and there is only one sampling point for a valley, an output is output to this valley. It becomes impossible to switch. As a result, in the example of FIG. 7B, two workpieces are erroneously detected as one workpiece.

  Similarly, when the threshold value is too high and two or more sampling points cannot be secured at a peak, it becomes impossible to switch the output for each workpiece, and erroneous detection occurs.

  In the tuning process described above, the received light amount when the workpiece is in the detection area and the received light amount when the workpiece is not in the detection area are acquired, and the threshold value is automatically set based on each received light amount. When threshold values are set based on the amount of light received from peaks and valleys with large variations in amplitude and large amplitudes, the threshold values are biased to either one of peaks or valleys with small amplitudes. . As a result, there is a possibility that erroneous detection as shown in FIG.

Focusing on the above problems, in this embodiment, one representative received light amount is extracted from each of the light incident period and the non-light incident period, and the minimum value (hereinafter referred to as MT) of the representative light received amount in each light incident period is extracted. _(Min .) is a peak value, and the maximum value (hereinafter referred to as VY _max ) of the representative received light amount in the non-light-incidence period is a bottom value. The display example shown in FIG. 5C displays MT _min and VY _max specified by this method.

  The representative received light amount is extracted based on the pulse count number P set in the detection process. Specifically, for the light incident period, when the light reception amounts during the period are arranged in descending order from the maximum value, the Pth received light amount is extracted as the representative light reception amount. When the received light amounts are arranged in ascending order from the minimum value, the received light amount located at the Pth is extracted as the representative received light amount.

  FIG. 8 shows a processing procedure for performing the display shown in FIG. 9A shows the detailed procedure of the light incident process (step S111) in FIG. 8, and FIG. 9B shows the detailed procedure of the non-light incident process (step S121) in FIG. Indicates. FIG. 10 shows an example in which the value of the buffer that stores the received light amount related to the specification of the representative received light amount during the light incident period changes.

  Hereinafter, the display processing of each representative received light amount will be described in detail with reference to these drawings. In this embodiment, a predetermined processing time is set to T seconds, and the passage of time is checked by a timer in the control unit 105.

In FIG. 8, in the first step S101, initialization processing is performed. In this initialization process, initial values are set for the peak value MT _min displayed on the display device 101, the bottom value VY _max displayed on the display device 102, and the two types of buffers mt (i) and vy (j). Processing is included.

In MT _min , the maximum value 9999 that can be displayed on the display unit 101 is stored as an initial value, and in VY _max , the minimum value 0 displayed on the display unit 102 is stored as an initial value.
The buffer mt (i) (i = 1 to P) stores the received light amount during the light incident period from the maximum value to the Pth in descending order, and 0 is stored as an initial value. vy (j) (j = 1 to P) is for storing the received light amount during the non-incident period from the minimum value to the Pth in ascending order, and 9999 is stored as an initial value.

After the initialization process, the timer is reset (step S102). Thereafter, the received light amount D is acquired at a timing according to the clock pulse (step S103), and the acquired received light amount D is compared with a threshold value to determine whether the light is incident or not (step S104).
Although details are omitted in FIG. 8, in step S <b> 104, switching between incident light and non-incident light is determined according to the same pulse count method as in the detection process. That is, if the received light amount D acquired in step S103 is equal to or greater than the threshold value, it is further determined that the received light amount that is equal to or greater than the threshold value is received P-1 times in succession and is in the incident light state. . Similarly, when the received light amount D acquired in step S103 is smaller than the threshold value, it is determined that the received light amount is smaller than the threshold value P-1 times continuously, and it is determined that the light is not incident.

  In the case where both the incident light and the non-incident light are changed to another state without continuing the same state P times (from the incident state where the received light amount D is equal to or greater than the threshold value to the non-incident state smaller than the threshold value). Or a change from a non-light incident state to a light incident state) is further determined by whether or not the state after the variation continues P times. The P received light amounts used for the determination are temporarily stored in the work buffer.

  If it is determined in step S104 that the light is incident, the process proceeds to the light incident process in step S111. If it is determined that the light is not incident, the process proceeds to the non-light incident process in step S121. Transition.

Here, assuming that the light incident state is determined in the first step S104 after the start of the process, details of the light incident process will be described with reference to FIG. 9A and FIG.
This process compares the received light amount D acquired immediately before with the value stored in the buffer mt (i), and when D is larger than the buffer mt (i), the buffer mt (i) is rewritten. Is what you do.

First, i = P is set in step S11, and the immediately preceding acquired received light amount D is compared with mt (i) in step S12.
If D> mt (i) when i = P, step S12 becomes “YES”, step S13 becomes “NO”, and the process proceeds to step S15. In step S15, the current value of mt (i) is discarded and the received light amount D is stored in mt (i).

  Thereafter, the process proceeds from step S16 to step S17, i is decremented (i = P-1), and in step S12, the value stored in the buffer mt (i) specified by the updated i is The acquired received light amount D is compared. At this stage, if D> mt (i), both step S12 and subsequent step S13 are “YES”, and the process proceeds to step S14.

  In step S14, the current value of the buffer mt (i + 1) is discarded, and the value of mt (i) is stored in this buffer mt (i + 1). In step S15, the received light amount D is stored in mt (i).

  Thereafter, until i becomes 1 (“YES” in step S16), the same processing as described above is repeatedly executed. However, when the received light amount D becomes mt (i) or less in the middle (step S12 is “NO”). ) Terminates the process.

FIG. 10 shows changes in values generated in the buffers mt (1), mt (2), and mt (3) when P = 3 and the light reception process is performed for three times of light reception.
In the buffers mt (1), mt (2), and mt (3), 0 is set as an initial value. Assuming that the initial received light amount D after initialization is 100, mt (1), mt (2), and mt (3) are all smaller than D, so the loop of steps S12 to S17 is repeated three times. .

  In the first loop, 100 is stored in mt (3) in step S15. In the second loop, 0 of mt (2) is moved to mt (3) by step S14, and 100 is stored in mt (2) by step S15. Further, in the third loop, 0 in mt (1) is moved to mt (2) in step S14, and 100 is stored in mt (1) in step S15.

  Assuming that the second received light amount D is 150, similarly to the above, the loop of steps S12 to S17 is repeated three times, and 150 is stored in mt (3) in the first loop. In the second loop, 0 of mt (2) moves to mt (3), and 150 is stored in mt (2). Further, in the third loop, 100 of mt (1) moves to mt (2), and 150 is stored in mt (1).

  If the amount of received light D for the third time is 80, a value 0 smaller than D is stored in mt (3) focused on in the first loop, so 80 is stored in mt (3) in step S15. Is done. However, in the second loop, since a value (100) greater than D is stored in mt (2) of interest, the determination in step S12 is “NO”, and the process ends. Thereby, the values of mt (2) and mt (1) are maintained.

  As described above, by performing the light reception process for each light reception amount during the light reception period, the maximum value of the light reception amount is stored in the buffer mt (1), and from the second highest light reception amount below. The received light amounts up to the P-th highest received light amount are sequentially stored in mt (2)... Mt (P).

The non-light incident process shown in FIG. 9B also proceeds in the same flow as the light incident process of FIG. 9A.
Briefly, processing is started with j = P (step S21), the value of the buffer vy (j) is compared with the acquired received light amount D (step S22), and the buffer vy (j) is smaller than the acquired received light amount. In the case (“YES” in step S22), the buffer vy (j) is rewritten to the acquired received light amount D (step S25). If j is smaller than P, the value of the buffer vy (j) is moved to vy (j + 1) before executing step S25 (steps S23 and S24).
The above process is continued by decrementing the value of j (step S27), when j becomes 1 (“YES” at step S26), or when vy (j) becomes less than or equal to the acquired received light amount D (Step S22 is “NO”), the process is terminated.

  As described above, by performing the non-incidence process for each received light amount during the non-incident period, the minimum value of the received light amount is stored in the buffer vy (1). Each received light amount from the amount to the Pth lowest received light amount is sequentially stored in the buffers vy (2)... Vy (P).

Returning to FIG.
In the light incident process according to the light incident determination in step S104 (step S111), the P received light amounts used for the above determination are sequentially set to D, and the process of FIG. 9A is executed. . Thereafter, on the condition that T seconds have not elapsed ("NO" in step S112), the amount of received light is acquired again (step S113), and it is determined whether or not the light reception amount D has switched to the non-incident state. To do.

  Even in this determination, it is determined that the light receiving amount smaller than the threshold value is obtained P times, and it is determined that the light receiving state is changed, and the loop of steps S111 to S114 is performed until it is determined that the light receiving state is not reached. repeat. As a result, the processing shown in FIG. 9A is executed for each light reception amount during the light incident period, and corresponds to the Pth counting from the light reception amount (maximum light reception amount) at the peak of the light reception amount in descending order. The received light amount is stored in the buffer mt (P).

When the light incident state is switched to the non-light incident state, the loop of steps S111 to S114 is terminated and the process proceeds to step S115, where the value of the buffer mt (P) is compared with MT _min . If mt (P) <MT _min (step S115 is “YES”), mt (P) is set to MT _min (step S116). If mt (P) is equal to or greater than MT _min (step S115 is “NO”), step S116 is skipped and the current value of MT _min is maintained.
Thereafter, the buffer mt (i) (i = 1 to P) is returned to the initial value 0 (step S117), and the process proceeds to the non-light incident process of step S121.

  Even in the non-light incident process of step S121, the P received light amounts used in the determination of step S104 or step S114 are sequentially set to D, and the process of FIG. 9B is executed. Thereafter, on condition that T seconds have not elapsed ("NO" in step S122), the amount of received light is acquired again (step S123), and it is determined whether or not the light reception state is switched by the acquired amount of received light D (step S123). Step S124).

  Even in this step S124, the determination is “NO” until the amount of received light equal to or greater than the threshold value D is received P times consecutively. By repeating the loop of steps S121 to S124 until it is determined that the light enters, the processing shown in FIG. 9B is executed for each received light amount during the non-light incident period. Thus, the Pth received light amount counted in ascending order from the bottom of the received light amount (minimum received light amount) is stored in the buffer vy (P).

When the non-light incident state is switched to the light incident state (“YES” in step S124), vy (P) is compared with VY _max in step S125. If vy (P)> VY _max (step S125 is “YES”), vy (P) is set to VY _max (step S126). On the other hand, when vy (P) is equal to or less than VY _max (step S125 is “NO”), step S126 is skipped.
Thereafter, the buffer vy (j) (j = 1 to P) is returned to the initial value of 9999, and the process proceeds to the light incident process in step S111. In step S111 as well, the process shown in FIG. 9A is executed for the P received light amounts used for the determination for the transition in order.

As described above, while determining the switching timing between the light incident state and the non-light incident state based on the amount of light received each time, the loop including the light incident time process (S101 to 104) and the loop including the non light incident time process (S111 to S111). 114). As a result, the P-th highest received light amount from the maximum value is extracted as the representative received light amount for each received light amount group (crest of received light amount) during the light incident period, and the minimum value among these representative received light amounts is MT _min. Stored in In addition, the P-th lowest received light amount counted from the minimum value is extracted as the representative received light amount for each received light amount group (received light valley) during the non-incident period, and the maximum value among the representative received light amounts is VY _max. Stored in

Finally, when the time measured by the timer reaches T seconds, step S112 or step S122 becomes “YES” and the process proceeds to step S105, where MT _min at that time is displayed as a peak value on the display 101, and VY _Max is displayed on the display 102 as a bottom value.

In FIG. 8, the process ends with the above display. Thereafter, the process waits for a user operation while appropriately switching between the state of displaying MT _min and VY _max and the display shown in FIG. When the user operates the up switch SW2 or the down switch SW3, the process ends, and the state shifts to a state in which a threshold value is displayed ((d) in FIG. 5).

In the above processing, these values can be output to an external device in accordance with the display of the peak value MT _min and the bottom value VY _max . Even when the sensor main body does not have a display unit, it is possible to output the specified MT _min and VY _max to an external device and display each value on an external monitor.

In the example of FIG. 8, the processing for specifying the peak value MT _min and the bottom value VY _max is performed once. However, the processing is not limited to this, and the processing illustrated in FIG. 8 is performed until an operation for setting a threshold value is performed. By repeating the above, the display of the peak value and the bottom value may be periodically updated. Further, the length of the processing cycle (T for T seconds) may be changed according to the user's setting operation. Furthermore, each value may be output to the outside or stored in the memory 106 in accordance with the display update.
In this way, even if it is difficult to directly recognize the change in the amount of received light due to the movement of the workpiece at a high speed, the workpiece can be detected based on the degree of variation in the displayed peak and bottom values. It is possible to know an approximate change in the amount of received light that accompanies the movement.

  According to the processing shown in FIGS. 8 and 9, the representative received light amount extracted from the peaks and valleys having the smallest margin with respect to the current threshold value among the peaks and valleys of the received light amount generated during T seconds. Are displayed as a peak value and a bottom value. In addition, when detection is actually performed based on each sampled received light amount, the value closest to the threshold value among the received light amount data necessary for determining the switching between the light incident state and the non-light incident state is , Specified as a peak value and a bottom value.

  Therefore, the user determines that a value having a margin with respect to both the displayed peak value and bottom value (for example, an intermediate value between the peak value and the bottom value) is an appropriate value of the threshold value, and switches the value. If the threshold value displayed according to the operation (see FIG. 5D) is a value close to the appropriate value, it is interpreted that the detection process can be stably executed. On the other hand, if there is a large difference between the appropriate threshold value and the displayed threshold value, the threshold value is biased and it may be necessary to change the threshold value. Recognize.

According to the processing shown in FIG. 8 and FIG. 9, when the threshold value is too high and the amount of received light exceeding the threshold value cannot be continuously received P times, The process is never performed, and as a result, MT _min becomes zero. Further, when the threshold value is too low and the received light amount smaller than the threshold value cannot be continuously received P times, the non-light incident process is not performed at all, and as a result, VY _max is 9999. In step S 105 when such a result is obtained, it is desirable to prompt an error display by displaying an error after displaying MT _min and VY _max or alternately with this display.

  On the other hand, when the value of the pulse count number P is relatively small (for example, P = 2 in the case of the fastest mode in FIG. 6) or when the detection process of the pulse count method is not performed, the maximum of each light incident period The smallest value in the amount of received light may be displayed as the peak value, and the largest value in the minimum amount of received light in each non-light incident period may be displayed as the bottom value.

  Further, in the above embodiment, the representative received light amount in each light incident period and each non-light incident period is compared for each type of period, the minimum value in the representative light received amount in the light incident period is a peak, and the non-light incident period Although the maximum value and the bottom value in the representative received light amount are set, the method for specifying the peak value and the bottom value is not limited to this. For example, for the light incident period, the average value of each received light amount from the maximum received light amount to the Pth highest received light amount is calculated, and the representative received light amount of the light incident period in which this average value is minimum is specified as the peak value. Also good. For the non-light-incident period, the average value of each received light quantity from the minimum received light quantity to the Pth lowest received light quantity is calculated, and the representative received light quantity of the non-light-incident period in which this average value is maximum is specified as the bottom value. May be.

Further, in the above embodiment, the peak value and the bottom value of the display target are specified from the predetermined amount of light received for T seconds. However, without specifying the processing period, MT _min and VY _max are set after the processing is started. These may be displayed in response to the first specification of values, and thereafter the display may be updated accordingly whenever the value of MT _min or VY _max is updated.
In this case, the user can determine the appropriate threshold value based on the stable display of the peak value and the bottom value.

  Further, in order to emphasize the accuracy of the detection processing of the pulse count method, when it is desired to grasp the variation in the amount of received light, the switching is performed every time the light incident period and the non-light incident period are switched by the process shown in FIG. The display may be updated with the representative light reception amount in the period immediately before.

The process of FIG. 11 will be described. In this embodiment, the peak value is MT and the bottom value is VY.
In the initialization process of the first step S201, 0 is stored in the buffer mt (i) (i = 1 to P) for storing the received light amount during the light incident period, and the received light amount during the non-light incident period is stored. 9999 is stored in the buffer vy (j) (j = 1 to P).

  Next, the received light amount D is acquired (step S202), and it is determined whether the light is incident or not. Also in this embodiment, the determination is confirmed when the same light receiving state continues P times, and when it is determined that the light is incident, the P received light amounts used for the determination are sequentially targeted. In step S211, the incident light process is executed. Similarly, when it is determined that the light is not incident, the P light reception amount used in the determination is sequentially processed, and the non-light incident process in step S221 is executed. The specific procedure of step S211 is the same as that shown in FIG. 9A, and the specific procedure of step S221 is the same as that shown in FIG. 9B.

  After the light incident process (step S211), the received light amount D is acquired again (step S212), and when it is determined that the light incident state continues with the received light amount D (step S213 is “NO”). Then, the light reception process (step S211) is executed again for the newly received light reception amount D as a target. Hereinafter, similarly, the acquisition of the received light amount D and the process during incident light are repeated until it is determined that the light incident state has been switched (“YES” in step S213).

  The buffer mt (P) when switched from the light incident state to the non-light incident state by the above-described series of processing (step S213: “YES”) is Pth higher than the maximum received light amount during the light incident period. The amount of received light is stored. In step S214, the value of mt (P) is set to MT, and in step S215, the buffer mt (i) is returned to the initial value of zero. Further, in step S216, MT is displayed on the display unit 101 as a peak value.

Even in the case where it is determined that light is not incident in step S203 and the non-light incident process (step S221) is performed, similarly, the process of acquiring the received light amount D until it is determined that the light incident state is switched (step S222). ) And non-light incident processing (step S221) are repeated. By this series of processing, when it is determined that the light incident state is switched to the light incident state (step S223 is “YES”), the light reception amount in the non-light incident period is Pth lower than the maximum value. The amount of received light is stored in the buffer vy (P). In step S224, the value of vy (P) is set to VY, and in step S225, the buffer vy (j) is returned to the initial value 9999. In step S226, VY is displayed on the display unit 102 as a bottom value.

Hereinafter, similarly, until an operation for switching the display of the display unit 100 is performed (“YES” in step S217), steps S211 to 216 or steps S221 to S226 are performed while discriminating switching between incident light and non-incident light. Run. If a switching operation is performed by the user at a predetermined timing, step S217 is “YES”, and the process is terminated.
In steps S211, S223, the determination of “YES” is made when the non-light incident state and the light incident state have continued P times. In steps S211 and S221 that have received the respective determinations, the P number used for the determination is determined. Are sequentially processed.

  According to the processing shown in FIG. 11, for each peak of received light amount, a value (P-th highest received light amount) closest to the current threshold value among the minimum received light amount for detecting the peak. ) Are extracted and displayed as peak values. In addition, for each valley of the amount of received light, a value closest to the current threshold value (Pth lowest received amount) is extracted from the minimum amount of received light that should be secured in order to detect the valley, and is used as the bottom value. Is displayed. Therefore, the user can grasp the variation between the peaks and valleys of the received light amount by displaying each time, and can determine whether the current threshold value is appropriate based on the margin of each value with respect to the threshold value.

  When the peak value MT and the bottom value VY are specified by the method shown in FIG. 11, the values of MT and VY for each time are stored in the memory 106 instead of or together with the process of displaying them. Each accumulated value may be output to an external device at a predetermined timing. Alternatively, every time a new peak value MT or a new bottom value VY is obtained, the value may be immediately output to an external device. In this way, it is possible to perform processing suitable for detailed analysis of the degree of variation of each value and the relationship with the threshold, such as displaying the peak value MT and the bottom value VY in each time series. Become.

  Further, the threshold value set prior to the processing of FIGS. 8 and 11 is not limited to that set by the tuning process, and a threshold value registered in the memory 106 by default may be used.

  Next, in the embodiments shown so far, on the assumption that a threshold value has been set in advance, the peak value is determined while determining the switching between the light incident period and the non-light incident period based on the threshold value. Although the threshold value and bottom value are specified, it is possible to extract the representative received light amount that will be the peak value and bottom value from the received light amount obtained within a certain time without setting the threshold value in advance. is there. Processing in that case will be described with reference to FIG.

  Also in this processing, P received light amounts are stored by two types of buffers mt (i) and vy (j), respectively. In the initialization process in step S301, 0 is stored in the buffer mt (i) and 9999 is stored in the buffer vy (j), as in the previous examples.

  Next, the internal timer is reset (step S302), the amount of received light is acquired in accordance with the clock pulse (step S303), and light incident processing (step S304) and non-light incident processing (step S304). Step S305) is executed in order. Detailed procedures of each process are the same as those shown in FIGS. 9A and 9B, respectively.

  Thereafter, on the condition that the predetermined T1 seconds have not elapsed (“NO” in step S306), a new received light amount is acquired (step S303), and the received light amount is set as the target at the time of light incident. Processing (step S304) and non-light incident processing (step S305) are executed. Thereby, in the buffer mt (i), the P received light amounts are arranged in descending order with the maximum value at the top, and in the buffer mt (j), the P received light amounts are arranged in ascending order with the minimum value at the top. .

  When T1 seconds have elapsed ("YES" in step S306), the process proceeds to step S307, where the value of the buffer mt (P) is displayed on the display unit 101 as a peak value, and the value of the buffer vy (P) is displayed as a bottom value. 102.

  According to the embodiment of FIG. 8, by determining the value of T1 according to the time taken to pass one workpiece, one peak and one valley of the received light amount are generated, and the maximum value in the peak is obtained. The Pth highest received light amount can be displayed as a peak value, and the Pth lowest received light amount counted from the minimum value in the valley can be displayed as a bottom value. Therefore, an appropriate value can be set as the threshold based on the relationship between these values.

  In the embodiment of FIG. 8 as well, if the procedure of steps S301 to S307 is repeated according to the passage of the workpiece without displaying the peak value and the bottom value only once, the workpiece is similar to the example of FIG. The variation between the peak value and the bottom value can be confirmed. Also in this embodiment, it is possible to accumulate the peak value and the bottom value every time in the memory 106 or output them to an external device. In addition, when considering changing the threshold value set for detection processing, switching between the light incident state and the non-light incident state is performed depending on the threshold value temporarily set as the changed value. While determining, the peak value and the bottom value can be obtained and displayed or output.

DESCRIPTION OF SYMBOLS 1 Photoelectric sensor 100 Display part 101,102 Display device 110 Operation part 103 Light projection part 104 Light reception part 105 Control part (CPU)
106 memory

Claims (8)

A light projecting unit that projects light for detection;
A light receiving unit that performs light reception processing according to the light projecting operation and outputs received light amount data ;
The process of acquiring the received light amount data from the light receiving unit and the process of determining whether the light incident state or the non-light incident state by comparing the received light amount indicated by the acquired received light amount data with a threshold value are repeated. In addition, when the result of this determination is switched, detection means for switching the output indicating the determination result on condition that the received light amount data for obtaining the same determination result as after the switching is acquired P times (P ≧ 2),
A plurality of incident periods in which P or more received light amount data indicating the amount of received light that is determined to be the incident light state by the currently set threshold value are obtained are obtained during each incident period of the object. The minimum value among the received light amounts indicated by the P received light amount data is specified as the representative received light amount in the light incident period, and indicates the received light amount that is determined as the non-light incident state by the currently set threshold value. For a plurality of non-light incident periods in which P or more received light quantity data are obtained , the maximum value among the received light quantities indicated by the P received light quantity data acquired during each target non-light incident period First representative received light amount specifying means for specifying the representative received light amount in the light incident period;
For each of the plurality of light incident periods, a minimum value among the representative light reception amounts specified by the first representative light reception amount specifying means is specified as a representative light reception amount representing a light incident state, and each of the plurality of non-light incident periods is specified. Second representative received light amount specifying means for specifying a maximum value among the representative received light amounts specified by the first representative received light amount specifying means as a representative received light amount representing a non-light incident state;
Output means for outputting information indicating the two representative received light amounts specified by the second representative received light amount specifying means for displaying each representative received light amount;
Photoelectric sensor provided . The first representative received light amount specifying means is positioned at the Pth when the received light amounts indicated by the received light amount data acquired during the light incident period are arranged in descending order of the size for each of the plurality of light incident periods. When the received light amount is specified as the representative received light amount in the light incident period, and the received light amount indicated by the received light amount data acquired in the non-light incident period is arranged in ascending order of size for each of the plurality of light incident periods The photoelectric sensor according to claim 1, wherein the Pth received light amount is specified as a representative received light amount in the non-light incident period . The second representative received light amount specifying means calculates a minimum value among the representative received light amounts specified by the first representative received light amount specifying means for each of a plurality of light incident periods that occur within a predetermined time period. The maximum value among the representative received light amounts specified by the first representative received light amount specifying means for each of a plurality of non-incident periods that occur within the predetermined time, specified as the representative received light amount representing the light incident state The photoelectric sensor according to claim 1 , wherein the light receiving amount is specified as a representative light receiving amount representing the non-light incident state. The first representative received light amount specifying means compares the received light amount indicated by the received light amount data from the light receiving unit with the threshold value, and determines the switching between the light incident period and the non-light incident period. Identify the amount of representative light received at
The second representative light amount specifying means, input each time the light period to the non-light incident period switching occurs, the first representative light receiving quantity with respect to a plurality of past light incident period dating back from the light incident period immediately before identify minimum value of the representative light receiving quantity that certain means identified as the representative light receiving quantity representing the entering-light state, the each time switched from the non-light incident period to the light entry period occurs, the non-light incident period immediately before identifying a maximum value in the first representative light receiving quantity specifying means has specified the representative light receiving quantity with respect to a plurality of non-light incident period in the past as the representative light receiving quantity representing the non-light incidence state dating back from claim 1 Or the photoelectric sensor described in 2 . The photoelectric sensor according to claim 1,
A photoelectric sensor further comprising setting means for accepting an operation of selecting one of a plurality of detection modes having different values of P and setting the value of P according to the selected detection mode in the detection means . 2. The photoelectric sensor according to claim 1, wherein the output unit includes a display unit for displaying two representative received light amounts specified by the second representative received light amount specifying unit. The photoelectric sensor according to claim 1,
An operation unit for performing an operation of changing the threshold;
The threshold value is set so that the threshold value set for the discrimination process of the detection means is displayed in conjunction with the display of the two representative light reception quantities specified by the second representative received light quantity specifying means. And a threshold value changing means for changing the threshold value according to an operation by the operation unit in a state where display is performed by this output. A light projecting unit that emits light for detection, a light receiving unit that performs light reception processing according to the light projecting operation and outputs light reception amount data, a process for obtaining light reception amount data from the light receiving unit, and the received light reception When the result of this determination is switched, the process is the same as after switching, while repeating the process of determining whether the light incident state or non-light incident state by comparing the amount of light received indicated by the amount data with a threshold value. Confirming the light reception state of the sensor for a photoelectric sensor having detection means for switching the output indicating the discrimination result on condition that the received light amount data for obtaining the discrimination result is acquired P times (P ≧ 2) continuously. A method for supporting the work to be performed,
A plurality of incident periods in which P or more received light amount data indicating the amount of received light that is determined to be an incident state based on a threshold value currently set in the photoelectric sensor are obtained , and the period for each incident period of light. The minimum value among the received light amounts indicated by the P received light amount data acquired therein is specified as the representative received light amount in the light incident period, and is determined as a non-light incident state based on the currently set threshold value. For a plurality of non-light incident periods in which P or more received light quantity data indicating the received light quantity are obtained, the maximum of the received light quantities indicated by the P received light quantity data acquired during each target non-light incident period Specify the value as the representative received light amount in the non-light-incidence period,
The minimum value among the representative received light amounts in each of the plurality of light incident periods is specified and displayed as the representative received light amount representing the light incident state, and the maximum of the representative received light amounts in each of the plurality of non-light incident periods is displayed. A method for supporting a work for confirming a light receiving state of a photoelectric sensor, characterized in that a value is specified and displayed as a representative light receiving amount representing a non-light incident state.

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