JP5034511B2 - Photoelectric sensor - Google Patents

Description

  The present invention relates to a fiber-type photoelectric sensor that detects a feature amount of a detection target by receiving reflected light or transmitted light of light projected on the detection target in a detection target region.

  The photoelectric sensor projects light such as visible light and infrared light as signal light from the light projecting unit, detects light reflected by the detection target object or light transmitted through the detection target by the light receiving unit, and detects the detection target object. An output signal indicating the feature amount is obtained. In this respect, the photoelectric sensor is used in various fields because it can detect an object in a non-contact manner and can also determine a color. For example, Patent Document 1 discloses a color identification device for projecting light of three colors onto a detection object and detecting the detection object based on color by receiving the reflected light or transmitted light. Yes. In recent years, a fiber type photoelectric sensor capable of detecting an object with a minute spot is known (Patent Document 2).

In these devices for detecting an object, a photodiode (PD) is generally used as a light receiving element. For example, in Patent Document 3 and Patent Document 4, a light receiving element that is a photodiode is set on a surface of a light receiving region. A method of designing so as to obtain a desired spectral sensitivity (for example, red, green, and blue) for each region is disclosed.
JP 2005-291748 A JP 2004-101445 A JP 09-210793 A JP 2004-214341 A

  However, there is a possibility that the designed spectral sensitivity cannot be sufficiently obtained by the conventional arrangement method of the light receiving elements.

FIG. 16 is a diagram for explaining the arrangement and amount of received light of a conventional light receiving element.
Referring to FIG. 16A, here, the light receiving elements for receiving red (R), green (G), and blue (B) are each 1/3 (for example, 120 degrees) in the circular area. The case where the light-receiving surface is formed by dividing the region into the regions of) is shown. Then, it is designed so that the reflected light or transmitted light of the detection target is irradiated near the center point (center), that is, a spot region is formed.

  The table of FIG. 16B shows the amount of light received by the light receiving element corresponding to each color when a spot region is formed near the center point. For example, when a spot region is formed near the center point (center), the received light amount can be detected equally for red (R), green (G), and blue (B). In the table, as an example, a case where red (R), green (G), and blue (B) are measured as received light amounts of 1000 each is shown.

  However, in the case of a fiber-type photoelectric sensor, the spot region moves greatly due to a slight angle shift. For example, consider a case where the spot region is shifted to the left as shown by the dotted line in FIG.

  In this case, as shown in FIG. 16B, only the received light amount of green (G) is measured as 3000, and the received light amounts of other red (R) and blue (B) are 0. Yes.

  That is, in such a case, there is a problem that red (R) and blue (B) cannot be measured, and the feature quantity of the measurement target cannot be stably detected.

  On the other hand, if the spot area is made sufficiently large with respect to the light receiving surface, it is possible to prevent a problem from occurring even when a positional deviation occurs. It is necessary to increase the distance, and it is difficult to reduce the size of the photoelectric sensor.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a photoelectric sensor that can stably detect a feature amount of a detection target.

  The photoelectric sensor according to the present invention is a photoelectric sensor that detects a feature amount of a detection target by receiving light of the detection target region, and receives light that is transmitted or reflected by the detection target of the detection target region. And a detection unit that detects a feature amount of the detection target based on a light reception result of the light receiving unit. The light receiving unit is provided in correspondence with each of the fibers for guiding the light transmitted or reflected through the detection target in the detection target region and the plurality of different wavelengths included in the light propagating through the fiber. A plurality of light receiving element groups that receive light of a corresponding wavelength. Each light receiving element group has a plurality of light receiving elements that receive light of a corresponding wavelength. The plurality of light receiving element groups are provided to face the fiber so as to form a light receiving surface. Each of the plurality of light receiving elements included in each light receiving element group is dispersedly arranged in accordance with a predetermined rule in the light receiving surface.

  Preferably, the plurality of light receiving element groups correspond to first to third light receiving element groups respectively provided to receive the wavelengths of red, green, and blue light included in the light propagating through the fiber. The plurality of light receiving elements included in the first to third light receiving element groups are arranged in a distributed manner to form an arrayed light receiving surface.

  In particular, the light receiving surface is formed based on a combination of 3 × 3 minimum units in which the first to third light receiving elements are arranged in a uniform number. Based on the shape and size of the output end face of the fiber and the distance between the output end face and the light receiving surface, a spot region of the fiber is formed on the arrayed light receiving surface. The distance between the output end face of the fiber and the arrayed light receiving surface is set so that the spot area of the fiber formed on the arrayed light receiving surface can surround at least one 3 × 3 minimum unit. The

  In particular, the fiber has a plurality of fiber cores. The spot region of the fiber includes the spot region of each fiber core formed on the arrayed light receiving surface based on the shape of the output end surface of each fiber core and the distance between the output end surface and the arrayed light receiving surface. The distance between the emission end face of the fiber core and the arrayed light receiving surface is such that the spot area of the fiber core formed on the arrayed light receiving surface can surround at least one 3 × 3 minimum unit. Is set.

In particular, the distance is set to less than 9 mm.
Preferably, the spectral sensitivities of the plurality of light receiving element groups are adjusted such that they overlap each other within a predetermined wavelength band, and the spectral sensitivities are maximized in the corresponding wavelength regions of light.

  A photoelectric sensor according to the present invention is a photoelectric sensor that detects a feature amount of a detection target by receiving light of a detection target in a detection target region, and includes a plurality of light receiving elements included in a plurality of light receiving pattern units. Is distributed and arranged according to a predetermined rule so as to face the fiber, so even if the position of the irradiation spot is shifted, it is possible to maintain the balance of the amount of light received by each light receiving element. Stable measurement of an object is possible.

  Embodiments of the present invention will be described in detail with reference to the drawings. Note that the same or corresponding parts in the drawings are denoted by the same reference numerals and description thereof will not be repeated.

  FIG. 1 is an external perspective view of the photoelectric sensor according to the embodiment of the present invention with the upper cover opened.

  Referring to FIG. 1, photoelectric sensor 1 according to the embodiment of the present invention has a multi-package plastic casing 101. The light projecting fiber 2 and the light receiving fiber 3 are inserted into the front portion of the housing 101 and are fixed to be detached by operating the clamp lever 103. The electric cord 4 is drawn out from the rear part of the casing 101.

  The illustrated electrical cord 4 includes a grounding (GND) core wire 41, a power source (Vcc) core wire 42, a detection output core wire 43, an auxiliary output core wire 44, and a remote input core wire 45. Have

  The casing 101 is fixed to a mounting surface such as a control panel via a DIN rail (not shown). What is indicated by reference numeral 104 is a DIN rail fitting groove. A transparent upper cover 102 is attached to the top of the housing 101 so as to be openable and closable. A first display 105, a second display 106, a first operation button (UP) 107, and a second operation button are provided on the upper surface of the casing 101 exposed when the upper cover 102 is opened. A (DOWN) 108, a third operation button (MODE) 109, a first slide operator (SET / RUN) 110, and a second slide operator (L / D) 111 are provided.

  FIG. 2 is a diagram illustrating an enlarged view of the operation / display unit of the photoelectric sensor according to the embodiment of the present invention.

  1 and 2, each of the first display 105 and the second display 106 is composed of a 4-digit 7-segment digital display, each of which includes a 4-digit number, an alphabet, The combination can be arbitrarily displayed.

  The first operation button 107, the second operation button 108, and the third operation button 109 all constitute a momentary type push button switch. As shown in FIG. 2, the first operation button Reference numeral 107 denotes an “UP key”, the second operation button 108 functions as a “DOWN key”, and the third operation button 109 functions as a “MODE key”.

  Each of the first slide operator 110 and the second slide operator 111 constitutes a slide switch. As shown in FIG. 2, the first slide operator 110 is a “SET / RUN changeover switch”. As described above, the second slide operator 111 is configured to function as an “L / D switch”.

  Referring again to FIG. 1, the housing 101 includes a light emitting element for detecting an object and a light receiving element for detecting the object, which are not shown. When the light projecting fiber 2 is firmly inserted into the fiber insertion hole, the end face of the light projecting fiber 2 and the light emitting part of the light emitting element for detection are firmly optically coupled, so that the light generated from the light emitting element for detection is Then, the light is projected from the fiber head (not shown) at the tip thereof to the detection target region via the light projecting fiber 2. Similarly, when the light-receiving fiber 3 is firmly inserted into the fiber insertion hole, the end face of the light-receiving fiber 3 and the light-receiving element for detection are optically coupled, and thereby introduced into the fiber from the fiber head of the light-receiving fiber 3 (not shown). The emitted light is guided to the light receiving fiber 3 and reaches the light receiving element for detection. The arrangement of the light emitting element for detection and the light receiving element for detection described above is the same as that employed in the conventional fiber type photoelectric switch of this type.

  Next, the electrical hardware configuration of the photoelectric sensor according to the embodiment of the present invention will be described.

FIG. 3 is a schematic block diagram of the photoelectric sensor according to the embodiment of the present invention.
Referring to FIG. 3, this circuit is mainly composed of a signal processing unit 200 mainly composed of a microprocessor. The signal processing unit 200 includes a microprocessor (not shown), a ROM storing a system program, a working RAM necessary for executing the program, and an EEPROM for storing various setting data. . The EEPROM stores data set by the manufacturer before shipment from the factory and various data set by the user after shipment from the factory. Such a configuration of the signal processing unit 200 is well known in various documents, and thus detailed description thereof will be omitted.

  On the left side of FIG. 3, a light projecting unit 202 having a light emitting element and a light receiving unit 203 having a light receiving element, which will be described in detail later, are illustrated. The light projecting unit 202 includes a light emitting diode (hereinafter referred to as an LED) 202a which is a light emitting element for detection, and an LED driving unit 202b for driving the LED 202a. On the other hand, the light receiving unit 203 includes a photodiode (hereinafter referred to as PD) 203a which is a light receiving element for detection, and an amplifier unit 203c for amplifying the output of the PD 203a. Note that light projecting unit 202 according to the embodiment of the present invention emits white light. In this example, the detection light-receiving element PD 203a is composed of three types of light-receiving elements that can receive red light, green light, and blue light, respectively.

  Then, the pulsed light generated from the LED 202a which is a light emitting element for detection by the action of the LED driving unit 202b is guided to the detection target region via the light projecting fiber 2. The light introduced into the light receiving fiber 3 by being transmitted or reflected in the detection target region reaches the PD 203a which is a light receiving element for detection via the light receiving fiber 3. The detection light receiving element PD203a receives light by three types of light receiving elements that can receive red light, green light, and blue light, respectively, and photoelectrically converts each color.

  An output signal generated by photoelectric conversion by the PD 203a is amplified by the amplifier unit 203c and then taken into the signal processing unit 200 via an A / D converter (not shown). In addition, since the basic structure of these light projection / reception is also well-known in various literature, the detailed description about this point is abbreviate | omitted.

  The display unit 204 is configured by a display for displaying data generated by various operations in the signal processing unit 200. More specifically, the display unit 204 is more specifically illustrated in FIGS. The first display 105 and the second display 106 described with reference to FIG. 2 are included. Various information is displayed on the first and second indicators 105 and 106 by numerical values, alphabets, combinations thereof, and the like.

  The input unit 205 is for inputting various types of information to the signal processing unit 200. The input unit 205 includes a key input unit 205a and a signal input unit 205b. The key input unit 205a is used by an operator to manually input various data. As described above with reference to FIGS. 1 and 2, the input unit 205a includes a first operation button. 107, a second operation button 108, a third operation button 109, a first slide operator 110, and a second slide operator 111 are included.

  On the other hand, the signal input unit 205b is for inputting a remote input signal via the core wire 45 of the electric cord 4 described above with reference to FIG. 1, and through this signal input unit 205b. A control signal input from the outside coming from the core wire 45 is taken into the signal processing unit 200.

  In this example, only one line is provided for the signal input unit 205b. However, it is naturally possible to input two or more lines, that is, a plurality of lines.

  The output unit 206 is for outputting various output signals generated by the signal processing unit 200 to the core wires 43 and 44 included in the electric cord 4. The output unit 206 includes an output unit 206a for outputting an object detection signal and an output unit 206b for an optional auxiliary output signal. That is, the detection signal for object detection generated by the signal processing unit 200 is sent to the core wire 43 in the electric cord 4 via the output unit 206a.

  Similarly, an arbitrary auxiliary output signal generated by the signal processing unit 200 is sent to the core wire 44 included in the electrical cord 4 via the output unit 206b. The core wires 43 and 44 included in these electric cords 4 are generally connected to an external host device such as a PLC or a PC. Similarly, the core wire 45 included in the electric cord 4 is also connected to an external host device such as a PLC or PC.

  The power supply unit 201 includes a power stabilization device that supplies power to each of the light projecting unit 202, the light receiving unit 203, the display unit 204, the input unit 205, and the output unit 206 shown in FIG. The power supply to the power supply unit 201 is performed through core wires 41 and 42 included in the electric cord 4. In this example, the core wire 41 is connected to GND, and the core wire 42 is connected to Vcc.

  Next, on the premise of the mechanical structure and electrical hardware configuration described above, various functions provided in this photoelectric sensor and the configuration of a system program executed by the signal processing unit 200 to realize them. explain.

  Generally, a photoelectric sensor has a plurality of functions that can be selectively executed (ON / OFF). Various options are available for each of these functions. Selection of these functions (ON / OFF) and selection of options can be performed by setting the photoelectric sensor to the SET mode. The operation of realizing the function set to ON according to a specific option can be performed by setting the photoelectric sensor to the RUN mode.

  The designation of whether the operation mode is the SET mode or the RUN mode is determined by whether the first slide operator 110 is set to the “SET” side or the “RUN” side, as shown in FIG. can do. The second slide operator 111 is for setting the logical polarity of the detection output signal of the photoelectric sensor. If the second slide operator 111 is set to the “L” side, the so-called light-on state is set. When the mode is set to “D”, the dark on mode is set.

  FIG. 4 is a diagram illustrating details of light projecting unit 202 and light receiving unit 203 according to the embodiment of the present invention.

  Referring to FIG. 4, light projecting unit 202 according to the embodiment of the present invention includes LED 202 a and LED driving unit 202 b as described above, and further controls LED driving unit 202 b to control the emission power of the LED. An LED drive adjustment unit 202bg for adjustment is included. The LED drive adjustment unit 202bg receives the monitoring result of the output power from the LED 202a from the signal processing unit 200 by an auto power control process described later, instructs the LED drive unit 202b, and supplies the LED drive unit 202b to the LED 202a. It is assumed that power control of the light emission current is performed.

  Light receiving unit 203 according to the embodiment of the present invention includes PD 203a and amplifier unit 203c as described above. The amplifier unit 203c is configured to amplify an electric signal obtained by photoelectrically converting the received signal light in the red, green, and blue wavelength regions output from the PD 203a, and an amplification adjustment that adjusts an amplification factor of the amplification unit. Part.

  In this example, as an example, the amplifier unit 203c includes an amplification unit 203r (also referred to as an R amplification unit) for amplifying an electric signal obtained by photoelectric conversion with respect to signal light in the red wavelength region, and an amplification unit 203c in the green wavelength region. An amplifying unit 203g (also referred to as a G amplifying unit) for amplifying an electric signal photoelectrically converted with respect to the signal light, and an amplifying unit 203b for amplifying the electric signal photoelectrically converted with respect to the signal light in the blue wavelength region. (Also referred to as a B amplification unit) is provided corresponding to each of the amplification units 203r, 203g, and 203b, and an amplification adjustment unit 203rg (also referred to as an R amplification adjustment unit) for adjusting the amplification factor of the corresponding amplification unit. , An amplification adjustment unit 203gg (also referred to as a G amplification adjustment unit) and an amplification adjustment unit 203bg (also referred to as a B amplification adjustment unit).

  The amplification adjustment unit 203rg, the amplification adjustment unit 203gg, and the amplification adjustment unit 203bg each adjust the amplification factor of the corresponding amplification unit in response to an instruction from the signal processing unit 200.

  FIG. 5 is a general flowchart schematically showing the entire system program executed by the CPU of the signal processing unit 200.

Referring to FIG. 5, the execution of this system program is started when the power is turned on.
In the figure, when the process is started, an initial setting process (step 401) is first executed. In this initial setting process (step 401), various initial setting processes necessary before starting a routine process to be described later are executed. In this initial setting process, initialization of various memories, indicator lamps, and control outputs, processing for reading necessary items from the EEPROM included in the signal processing unit 200, data checking, and the like are executed.

  When the execution of the initial setting process (step 401) is completed, the routine is shifted to a routine process. First, the setting state of the first slide operator 110 is referred to (step 402). If the first slide operator 110 is set to the “SET” side (step 402 SET), then the SET mode initial setting process (step 403) is executed. In the SET mode initial setting process (step 403), initialization of the measurement values for the SET mode, initialization of the function number (F) (F = 0), and the like are performed.

  When the execution of the SET mode initial setting process (step 403) is completed, as long as the first slide operator 110 is set to the “SET” side (step 405 YES), the SET for various functions (F) is performed. Mode processing (step 404) is executed. In this state, by appropriately operating the first operation button 107, the second operation button 108, and the third operation button 109, the user turns on various functions (F) prepared for the photoelectric sensor. / OFF setting, and further, individual setting processing for each function (F) can be executed.

  On the other hand, as a result of referring to the setting state of the first slide operator 110, if it is determined that the setting is set to the “RUN” side (step 402RUN), then the RUN mode initial setting process (step 406) is executed. The In this RUN mode initial setting process (step 406), initialization of indicator lamps, control output, threshold values and various RUN mode setting values, and the like are performed.

  When the RUN mode initial setting process (step 406) is completed, the RUN mode process (step 407) is executed as long as the first slide operator 110 is set to the “RUN” side (YES in step 408). In the RUN mode process (step 407), various functions selectively set by the user are realized in addition to the basic operation necessary for the photoelectric sensor. The specific contents of the RUN mode processing will be described later in detail as necessary.

  As described above, the system program executed by the signal processing unit 200 includes an initial setting process (step 401) that is an initial process performed immediately after power-on, and two processes that are routine processes, that is, a SET mode process ( Step 404) and RUN mode processing (Step 407).

FIG. 6 is a flowchart showing the entire SET mode processing.
Referring to FIG. 6, when the process is started, a function-specific display process (step 501) is first executed. In this function-specific display process (step 501), various display processes corresponding to the function number F are executed.

  Subsequently, a key input detection process is executed (step 502), and a wait state is made for the presence or absence of a key input operation on the operation buttons 107 to 109 and the slide operators 110 and 111 shown in FIGS. 1 and 2 (NO in step 503). ).

  In this state, it is determined that there is a key input (step 503 YES), and if a key input sequence corresponding to function switching is confirmed (YES in step 504), each time a function switching command is confirmed, the function number (F) The value is incremented by +1 until the total number of functions is reached (steps 505 and 506 NO), reaches the total number of functions (YES in step 506), is reset again to zero (step 507), and the function (F) is cyclically switched. The

  In this state, when selection regarding function F set at that time is instructed (steps 504 NO, 508 YES), the function-specific execution process is executed, and the process corresponding to function number F is performed (step 509). In the function-specific execution process, for example, the function F is switched according to the key operation of the operation button 107 or 108, and the corresponding process corresponding to the function number F is executed according to the switch.

  In addition, since the function number or the code corresponding to the function F is displayed on the above-described display unit 204 according to the switching of the function F, the user can select what function to the sensor according to the contents displayed by the guidance. It is possible to easily visually check whether the realization means is provided.

An example of a function provided as the SET mode process will be described.
FIG. 7 is a flowchart for explaining the setting of the teaching process provided as the SET mode process.

  Referring to FIG. 7, when processing is started, when the function designated by the user's key operation or an external signal is a one-point teaching function, for example, when the one-point teaching function is selected in step 901 ( In the case of YES), a one-point teaching process is executed (step 902). On the other hand, when the two-point teaching function is selected in step 903 (in the case of YES), a two-point teaching process is executed (step 904).

  Here, “one-point teaching process” means sampling the amount of received light of a reference object (also referred to as a reference object), and setting a threshold value to a lower or higher value by a certain value from the received light amount. It is a function. “Two-point teaching process” means sampling the received light amount of one of the two detection objects, sampling the acquired sampling value and the received light amount of the other detection object, and acquiring the acquired sampling value. This is a function for setting a threshold value in the middle of the value. That is, according to the two-point teaching function, the threshold value = (first sampling value + second sampling value) / 2.

  After these teaching processes are completed, it is determined whether or not a teaching error has occurred (step 905). For example, when there is a teaching error, it can be determined by determining a flag by setting a flag or the like.

  If there is a teaching error (in the case of YES), a message to that effect is displayed to the user, or a teaching error process for adjusting the parameters and executing the teaching again is executed (step 906).

  When there is no teaching error (in the case of NO), data such as a threshold value obtained by teaching processing is written to the EEPROM (step 907). The data written in the EEPROM is read out in the later RUN mode and used to calculate the feature quantity of the detection target.

Next, returning to FIG. 5 again, the RUN mode processing will be described.
Prior to introduction into the RUN mode, first, an RUN mode initial setting process is executed (step 406). In this RUN mode initial setting process (step 406), initial setting processes of various flags, counters, registers, and the like necessary for executing the RUN mode are performed. Subsequently, when the RUN mode initial setting process (step 406) is completed, the RUN mode process (step 407) is repeatedly executed as long as the first slide operator 110 is set to the “RUN” side (YES in step 408). Is done.

FIG. 8 is a flowchart for explaining the RUN mode processing.
The entire RUN mode process is roughly divided into a normal process and an interrupt process.

  FIG. 8A is a flowchart for explaining a normal process in the RUN mode process, and FIG. 8B is a flowchart for explaining an interrupt process in the RUN mode process.

  The interrupt process (steps 806 to 808) is executed by timer interrupt every time Tsec (for example, every 100 μsec).

  First, the normal process (steps 801 to 805) will be described with reference to FIG.

  When the process is started, an indicator light control process (step 801) is executed. In the indicator light control process (step 801), lighting control of the first and second indicators 105 and 106, which are 7-segment digital indicators, is performed according to the designated display contents.

  Subsequently, an auto power control (hereinafter referred to as APC) process (step 802) is executed. In this APC process (step 802), the monitor light reception amount acquired in a measurement light projecting / receiving process (step 806) described later is monitored, and APC correction is performed at regular intervals. In this example, the APC correction is performed by the power control of the projection current as described above.

  Subsequently, key input detection processing (step 803) is executed. In this key input detection process (step 803), a key input is detected at regular intervals. If an input is detected, a setting is made so that the corresponding process can be executed. Subsequently, an input key corresponding process (step 804) is executed, and various processes corresponding to the detected key input are executed.

  When the input key handling process (step 804) is completed, an external input process (step 805) is executed. Note that these RUN mode processes are processes provided in a general photoelectric sensor, and thus detailed description thereof is omitted.

  Next, with reference to FIG. 8B, interrupt processing executed every time Tsec will be described.

  When the interruption process is started, a light projecting / receiving process (step 806) is first executed. In this light projecting / receiving process (step 806), the LED 201a shown in FIG. 3 is pulse-driven through the light projecting drive unit 201b to generate white light, which is then projected through the light projecting fiber 2. (Not shown) and emitted from the projection head to the detection target area. At the same time, the reflected light from the detection target in the detection target region is introduced into the light receiving fiber 3 from the light receiving head provided at the tip of the light receiving fiber 3, and this is introduced to the PD 202b via the light receiving fiber 3. The signal obtained by photoelectric conversion by the PD 202b is amplified by the amplifier unit 203c, and then the amplified output is taken into the signal processing unit 200 via the A / D converter 202c. Thereby, the received light amount including the feature amount corresponding to the state of the detection target region is acquired by the signal processing unit 200.

  Subsequently, an ON / OFF determination process (step 807) is executed. In this ON / OFF determination process (step 807), a so-called coincidence value calculated based on the amount of light received by the detection target is discriminated based on a preset ON / OFF determination light amount threshold value. By determining the value, the presence / absence of an object in the detection target region is determined. That is, if the target object exists in the detection target region, the determination result is ON, and if it does not exist, the determination result is OFF.

  When the execution of the ON / OFF determination process (step 807) is completed in this way, the output control process (step 808) is subsequently executed, and the detection output signal generated by the signal processing unit 200 is electrically connected via the output unit 209. It is sent out to an object detection signal output core wire 43 included in the code 4. The detection output signal thus output to the core wire 43 is sent to a host device such as a PLC or a PC.

  FIG. 9 is a diagram illustrating the structure of the front region of housing 101 of photoelectric sensor 1 according to the embodiment of the present invention.

  Referring to FIG. 9, here, a cross-sectional view of the side surface portion of the entire region of the housing 101 of the photoelectric sensor 1 is shown. Holder elements 10 and 11 into which the light projecting fiber 2 and the light receiving fiber 3 can be respectively inserted are provided, and the light projecting fiber 2 and the light receiving fiber 3 are fixed by being inserted into the holder elements 10 and 11.

  Further, the LED chip 13 and the PD chip 14 are provided on the printed circuit board (PWB), and white light is introduced from the LED 16 provided in the LED chip 13 into the light projecting fiber 2 inserted into the holder element 10. . Further, the light reflected from the detection object is irradiated from the light receiving fiber inserted into the holder element 11 onto the photodiode (PD) that forms the light receiving surface which is the light receiving area of the PD chip 14. The light receiving fiber 3 inserted into the holder element 11 is provided to face a photodiode (PD) that forms a light receiving surface that is a light receiving region. A predetermined distance is set between the output end face of the fiber. This distance will be described later.

FIG. 10 is a diagram illustrating the shape of the PD chip 14 according to the embodiment of the present invention.
Referring to FIG. 10A, here, the height of the side surface portion of the PD chip 14 is shown, and as an example, the case of a chip having a height of 0.75 mm is shown.

  With reference to FIG. 10B, a view of the PD chip 14 as viewed from above is shown. Four lead terminals are provided around the chip, and a light receiving region is provided at the center. As an example, a chip size of 5 mm × 5 mm is shown.

  FIG. 11 is a diagram illustrating a part of the layout of the light receiving elements provided in the light receiving region of PD chip 14 according to the embodiment of the present invention.

  Referring to FIG. 11, the vertical and horizontal sizes of one light receiving element shown here are designed to be about 66 μm and about 71 μm, respectively. And in order to form a light-receiving surface, it arrange | positions at the 12x12 array form arrange | positioned 12 pieces each in the X direction and the Y direction. The vertical and horizontal sizes of the light receiving surface formed by the light receiving elements arranged in a 12 × 12 array are designed to be about 0.89 mm and about 0.91 mm, respectively, taking into account the spacing between the light receiving elements. Has been.

  FIG. 12 is a diagram for explaining a pattern of light receiving elements arranged in an array forming a light receiving surface.

  Referring to FIG. 12, here, as an example of the pattern of a 12 × 12 array of light receiving elements, a light receiving pattern unit configured in units of 3 × 3 is formed in combination.

  Specifically, focusing on the upper left 3 × 3 light receiving pattern unit, three light receiving elements for receiving red light, three light receiving elements for receiving green light, and three blue lights The light receiving element for receiving light is uniformly included in the 3 × 3 light receiving pattern unit. As shown in an enlarged view on the right side, as an example, the first row is red (R), green (G), and blue (B) from the left, and the second row is green (G), blue ( B) and red (R), and the third row is arranged in the order of blue (B), red (R), and green (G) from the left.

  The pattern of the 12 × 12 array of light receiving elements in this example is such that each 3 × 3 light receiving pattern unit adjacent in the X direction is symmetrical with respect to the Y axis, and each light receiving pattern unit is provided. It has been. Each of the 3 × 3 light receiving pattern units adjacent along the Y direction is provided with a light receiving pattern unit in an array that is symmetric with respect to the X axis.

  The light receiving elements for receiving red (R), green (G), and blue (B) light are distributed and arranged according to the arrangement pattern of the 12 × 12 array of light receiving elements in this example. .

  For example, as shown in FIG. 12, consider a case where light emitted from the end face of the fiber is irradiated onto the light receiving surface and a circular spot region is formed in the vicinity of the central region.

  Here, looking at the number of light receiving elements generally included in the circular spot region, it is about six red (R), eight green (G), and seven blue (B). Therefore, it is possible to detect the received light amount almost uniformly with no significant difference between the colors.

  Next, for example, consider a case where a circular spot region is shifted near the lower region. Here, looking at the number of light receiving elements generally included in the circular spot region, there are about 10 red (R), 8 green (G), and 8 blue (B). Therefore, the number of light receiving elements for receiving red (R), green (G), and blue (R) light in the spot region does not change significantly by arranging the light receiving elements in a dispersed manner. .

  Therefore, even if the spot area is shifted, the light receiving element pattern arranged in the array form the light receiving surface according to the embodiment of the present invention can sufficiently detect the received light amount with no difference in variation for each color. It is possible. Therefore, it is possible to detect the feature amount of the detection target stably.

FIG. 13 is a diagram illustrating the configuration of a multi-core fiber.
As shown in FIG. 13, the multi-core fiber has a double structure of a plurality of fiber cores (cores) and a clad covering the plurality of fiber cores.

  Here, as an example, the shape of the end face of the fiber core is formed in a hexagonal shape, and has a honeycomb structure.

  In the case of a multi-core fiber, the light receiving surface can be irradiated with reflected light guided from each of the plurality of fiber cores. That is, in the case of a multi-core fiber, since the positions of the plurality of fiber cores covered with the cladding are different, the emission positions from the respective fiber cores are also different.

  Therefore, the positions of the spot regions of the fiber cores formed on the light receiving surface are also different. Therefore, in the arrangement configuration of the conventional light receiving element described in FIG. 16, even if the positional deviation of the entire fiber does not occur, if the position of the fiber core that forms the spot region on the light receiving surface is close to the cladding, The spot area will deviate from the central area. That is, since the positions of the spot regions are different between the side closer to the clad and the side far from the clad, the amount of received light cannot be detected uniformly for each of the three colors, and there is a possibility that the bias of any color becomes large.

  On the other hand, as shown in FIG. 12, the positions of the fiber cores of the multi-core fibers forming the spot regions are different by forming a pattern in which light receiving elements of three colors are dispersedly arranged in an array. However, it is possible to detect the amount of light received evenly for each of the three colors, and to suppress color deviation.

FIG. 14 is a diagram illustrating a spot area according to the embodiment of the present invention.
Referring to FIG. 14A, here, a diagram is shown in the case where the light receiving surface on which arrayed light receiving elements are arranged is irradiated from the fiber end surface (output end surface) of the fiber having a core diameter of Dmm. .

  The distance from the fiber end surface to the light receiving surface (the light receiving surface distance is Lmm). This distance indicates the length from the center point of the fiber end surface to the center axis of the fiber contacting the light receiving surface. To do. In addition, the vertical and horizontal lengths of the light receiving elements forming the light receiving surface will be described as Xamm and Yamm, respectively.

  Referring to FIG. 14B, here, it is a diagram for explaining the irradiation spot diameter of a fiber having a core diameter Dmm.

  Referring to FIG. 14B, if irradiation is performed from the output end face of the fiber with a general spread angle of about 30 °, for example, the irradiation spot diameter is expressed by the following equation.

  Referring to FIG. 14C, here, a 3 × 3 light receiving pattern unit is shown. As described above, the spot area of the fiber is formed on the light receiving surface based on the shape and size of the output end face of the fiber and the distance between the output end face and the light receiving surface. The fiber spot area is set so that it can surround at least one 3 × 3 minimum unit. It is estimated that the balance of the received light amounts of red (R), green (G), and blue (B) can be maintained if at least a spot region surrounding the 3 × 3 minimum unit is obtained.

For example, where, when calculating the matrix area S surrounded by a circle when the spot diameter is Ar, matrix area surrounded by the spot diameter Ar is represented as Ar ^2/2 = S. In the case of the single light receiving element of this embodiment, the matrix area is about 0.042 mm ² because the vertical and horizontal sizes are designed to be about 66 μm and about 71 μm, respectively. Here, assuming that the matrix area is a square, if the spot diameter Ar is set to 0.289 mm or more, a minimum unit of 3 × 3 minimum units can be enclosed.

  Therefore, by calculating the minimum spot diameter from the matrix area constituting the 3 × 3 minimum unit, it is necessary to surround the 3 × 3 minimum unit using the value of the core diameter D using the above equation. It is possible to calculate the minimum distance L between the fiber end surface and the light receiving surface.

  FIG. 14D is a diagram for explaining the spot diameter and distance when an actual standard fiber and a multi-core fiber are used. Here, for simplification of explanation, it is assumed that the fiber end face is circular and a circular spot region is formed.

  For example, as shown in FIG. 14D, a case of a φ1 mm standard fiber will be described. Here, D = 1 mm. As an example, the distance L is set to 0.8 mm.

Then, the spot diameter is about 1.95 mm based on the above formula. When a matrix area that can be surrounded by a circular region having a spot diameter of 1.95 mm is calculated, S = 1.95 mm ² is obtained. Therefore, a 3 × 3 light receiving pattern unit that is a sufficiently large spot area with respect to the minimum matrix area S # calculated above and uniformly receives red (R), green (G), and blue (B) light. Thus, it is possible to detect the received light amount evenly for each of the three colors without color deviation.

Similarly, when the φ0.5 mm thin fiber is calculated under the same conditions, the spot diameter is 1.38 mm, and the matrix area that can be surrounded by a circular region with a spot diameter of 1.38 mm is S = becomes 0.95 mm ² approximately, likewise will contain a large number of light receiving patterns unit of 3 × 3 also in this case, it is possible to detect the color bias without three colors evenly amount of received.

  Next, consider a φ0.07 mm multi-core fiber. Consider a single fiber core. Here, D = 0.075 mm. The distance L is set to 0.29 mm.

Then, the spot diameter is about 0.38 mm based on the above formula. When a matrix area that can be surrounded by a circular region having a spot diameter of 0.38 mm is calculated, S = about 0.072 mm ² . Therefore, it is possible to enclose a minimum unit of 3 × 3 that is larger than the minimum matrix area S # calculated above.

  Because the spot area is very small, the spot area of a specific fiber core may be biased due to the different number of light receiving elements arranged for each of the three colors. In this case, since the spot area of each fiber core includes the minimum unit in which the light receiving elements are uniformly arranged 3 × 3, the light reception amount is detected uniformly for each of the three colors as a whole. Can be suppressed.

  Next, the case where the distance L is set to 0.2 mm for a φ0.07 mm multi-core fiber will be described.

Then, the spot diameter is about 0.30 mm based on the above formula. When a matrix area that can be surrounded by a circular region having a spot diameter of 0.30 mm is calculated, S = about 0.045 mm ² . Therefore, it is considered to be equal to or larger than the minimum matrix area S # calculated above and can surround a 3 × 3 minimum unit.

  In addition, when the spot region is made minute by reducing the distance in this way, as described above, the number of light receiving elements arranged for each of the three colors is different for the spot region of a specific fiber core, resulting in a color bias. There is a possibility, but when considered as a plurality of fiber cores as a whole, since the spot area of each fiber core includes a minimum unit in which light receiving elements are uniformly arranged in 3 × 3, The amount of received light is detected uniformly for each of the three colors, and it is possible to suppress color deviation.

  Further, as shown in the table of FIG. 14D, the 3 × 3 minimum unit light receiving pattern unit is sufficiently surrounded by the distance L of less than 1 mm, and stable detection is possible. That is, the distance L between the fiber end surface and the light receiving surface can be shortened by the method according to the present embodiment, and the photoelectric sensor can be secured while sufficiently securing the amount of light emitted from the output end surface of the fiber core. It is also possible to reduce the size.

  Here, the point that stable detection is possible even when the distance L is shortened has been described. However, in the case of a multi-core fiber, the distance L is preferably about 1 mm. The distance L can be set to less than 9 mm, which is shorter than the distance L, because the photoelectric sensor is molded with an outer width of about 10 mm.

  In this example, the case where a single light receiving element is designed with vertical and horizontal sizes of about 66 μm and about 71 μm, respectively, has been described as an example. However, the present invention is not limited to this size and can be freely designed. It is possible to calculate and set the optimum distance based on the same idea as described in the above.

  Further, the shape of the light receiving element is not limited to the rectangular shape as described in this example, and may be a square shape, a substantially circular shape, a honeycomb shape, or a substantially polygonal shape.

  In this example, the rectangular light receiving surface in which the light receiving elements are dispersedly arranged in an array has been described. However, the present invention is not limited to this, and may have any shape, for example, the circular shape described in FIG. A substantially polygonal shape may be used. In any case, the same effect can be expected if light receiving elements for receiving three colors of red, green, and blue light are dispersedly arranged in the light receiving surface.

  Further, in this example, the case where the light receiving surface is provided using the light receiving pattern unit in which the light receiving elements corresponding to 3 × 3 colors are uniformly provided has been described. However, the light receiving elements corresponding to the respective colors are substantially uniform. It is possible to provide a light receiving surface by using the provided 4 × 4 light receiving pattern unit, and it is also possible to provide a light receiving surface using an n × n light receiving pattern unit according to a similar method.

  Further, in this example, the configuration in which the light receiving elements constituting each light receiving element group are dispersedly arranged on the light receiving surface has been described for three types of light receiving element groups for receiving red, green, and blue light. However, the present invention is not limited to this, and it is also possible to provide a plurality of types of light receiving elements for receiving light of other colors, that is, to disperse the light receiving elements of the plurality of types of light receiving element groups. is there.

FIG. 15 is a diagram illustrating the spectral sensitivity of the light receiving element according to the embodiment of the present invention.
Referring to FIG. 15, here, spectral sensitivities of three types of light receiving elements provided for detecting red light, green light, and blue light are shown.

  The spectral sensitivities of these three types of light receiving elements are adjusted so that they overlap each other within a predetermined wavelength band and the spectral sensitivities are maximized in the corresponding wavelength regions of light.

  As shown in FIG. 15, the spectral sensitivity is designed to react not only in the target wavelength region but also in other wavelength regions, so that it is possible to cope with the reflectance characteristics of all detection objects. ing.

  In this example, the reflective photoelectric sensor, that is, the photoelectric sensor that receives the reflected light reflected by the detection target in the detection target region and detects the feature amount of the detection target has been described. However, the present invention is not limited to this, and can also be applied to a transmissive photoelectric sensor, that is, a photoelectric sensor that detects transmitted light that has passed through a detection target having a detection target force and detects a feature amount of the detection target. That is, in this case, the light guided to the light receiving fiber is not reflected light but transmitted light, and the other systems are the same.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is an external appearance perspective view in the state where the upper cover of the photoelectric sensor according to the embodiment of the present invention was opened. It is a figure explaining the enlarged view of the operation and the display part of the photoelectric sensor according to embodiment of this invention. 1 is a schematic block diagram of a photoelectric sensor according to an embodiment of the present invention. It is a figure explaining the detail of the light projection part 202 and the light-receiving part 203 according to embodiment of this invention. 3 is a general flowchart schematically showing an entire system program executed by a CPU of a signal processing unit 200. It is a flowchart figure which shows the whole SET mode process. It is a flowchart explaining the flow of teaching processing. It is a flowchart figure explaining a RUN mode process. It is a figure explaining the structure of the front area | region of the housing | casing 101 of the photoelectric sensor 1 according to embodiment of this invention. It is a figure explaining the shape of PD chip | tip 14 according to embodiment of this invention. It is a figure explaining a part of layout of the light receiving element provided in the light receiving region of PD chip 14 according to the embodiment of the present invention. It is a figure explaining the pattern of the light receiving element arrange | positioned at the array form which forms a light-receiving surface. It is a figure explaining the structure of a multi-core fiber. It is a figure explaining the spot area | region according to embodiment of this invention. It is a figure explaining the spectral sensitivity of the light receiving element according to embodiment of this invention. It is a figure explaining arrangement | positioning and the amount of light reception of the conventional light receiving element.

Explanation of symbols

  1 photoelectric sensor, 2 light emitting fiber, 3 light receiving fiber, 4 electric cord, 41 GND core wire, 42 Vcc core wire, 43 detection output signal core wire, 44 auxiliary output signal core wire, 45 for control signal Core wire, 101 housing, 102 transparent cover, 103 clamp lever, 104 DIN rail fitting groove, 105 first indicator, 106 second indicator, 107 first operation button, 108 second operation button, 109 3rd operation button, 110 1st slide operation element, 111 2nd slide operation element, 200 Signal processing part, 201 Power supply part, 202 Light projection part, 202a LED, 202b Light projection drive part, 203 Light reception part, 203a PD, 203c amplifier unit, 204 display unit, 205 input unit, 205a key input unit, 205b signal input unit, 206 Power unit, an output unit for 206a detection signal, an output unit for 206b auxiliary output signal.

Claims (5)

A photoelectric sensor that detects a feature amount of a detection target by receiving light of a detection target region,
A light receiving unit that receives light transmitted or reflected from the detection target in the detection target region;
A detection unit that detects a feature amount of the detection object based on a light reception result of the light receiving unit;
The light receiving unit is
A fiber for guiding the light transmitted through or reflected by the detection target in the detection target region;
Including first to third light receiving element groups provided correspondingly to receive the wavelengths of red, green and blue light contained in the light propagating through the fiber ,
Each of the light receiving element groups has a plurality of light receiving elements that receive light of a corresponding wavelength,
The first to third light receiving element groups are provided to face the fiber so as to form a light receiving surface,
The light receiving surface is formed on the basis of a combination of a plurality of 3 × 3 unit units arranged so that the light receiving elements of the first to third light receiving element groups have a uniform number. Is a photoelectric sensor provided symmetrically with adjacent unit units . Based on the shape and size of the exit end face of the fiber and the distance between the exit end face and the light receiving face, a spot region of the fiber is formed on the arrayed light receiving face,
The distance between the emission end face of the fiber and the arrayed light receiving surface is such that the spot area of the fiber formed on the arrayed light receiving surface can surround at least one 3 × 3 minimum unit. The photoelectric sensor according to claim 1, which is set as follows. The fiber has a plurality of fiber cores;
The spot region of the fiber is formed by the shape of the emission end face of each fiber core and the distance between the emission end face and the array-like light receiving face of each fiber core formed on the array-like light receiving face. Including spot areas,
The distance between the emission end face of the fiber core and the arrayed light receiving surface is such that the spot region of the fiber core formed on the arrayed light receiving surface surrounds at least one 3 × 3 minimum unit. The photoelectric sensor according to claim 2, wherein the photoelectric sensor is set so that The photoelectric sensor according to claim 2, wherein the distance is set to be less than 9 mm . 2. The photoelectric sensor according to claim 1, wherein spectral sensitivities of the plurality of light receiving element groups are adjusted so that the spectral sensitivities overlap each other within a predetermined wavelength band and the spectral sensitivities become maximum in the corresponding wavelength regions of light.

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