JP2017110926A - Photoelectric switch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photoelectric switch for suppressing a decrease in discrimination sensitivity of color.SOLUTION: A photoelectric switch comprises: light projection means for projecting detection light DL toward a detection area; light reception means for receiving reflection light RL from the detection area and converting the light to a light reception signal; correction instruction reception means for receiving a correction instruction; amount-of-return-light acquisition means for acquiring a reception light signal according to a correction instruction and designating the amount of reception light for each specific wavelength as the amount of return light; return light correction means for correcting a reception light signal based on the amount of return light; color information acquisition means for acquiring color information by comparing the amount of reception light of at least two specific wavelengths, based on a light reception signal after correction by the return light correction means; reference color intake instruction reception means for receiving a reference light intake instruction; reference color acquisition means for designating color information acquired according to the reference color intake instruction as a reference color; degree-of-coincidence calculation means for obtaining a degree of coincidence by comparing successively acquired color information with a reference color; and detection signal output means for performing work determination by comparing the degree of coincidence with a determination threshold and outputting a detection signal.SELECTED DRAWING: Figure 14

Description

  The present invention relates to a photoelectric switch, and more particularly, to an improvement in a photoelectric switch that receives a reflected light from a detection region and determines a workpiece.

  A photoelectric switch is a detection device that detects light using light, projects detection light, receives reflected light or transmitted light from the work, etc., makes a work determination, and detects a signal based on the result of the work determination. Is generated. The photoelectric switch includes a received light amount type photoelectric switch that performs workpiece determination based on the amount of reflected or transmitted light received from a detection area including the workpiece, and a distance measurement type photoelectric switch that measures the distance to the workpiece and performs workpiece determination. There are a switch and a color discrimination type photoelectric switch that discriminates the color of the workpiece surface and discriminates the workpiece.

  Light-receiving-type photoelectric switches use the fact that the amount of received light varies due to differences in the reflectance or color of the workpiece surface, differences in the distance to the workpiece, differences in the tilt (tilt angle) of the workpiece surface, etc. This is a general-purpose photoelectric switch that can be applied to many purposes. On the other hand, the distance measurement type photoelectric switch measures a feature by measuring the feature depending on the shape of the workpiece as the distance to the workpiece, and changes the reflectance and color of the workpiece surface, and the tilt (tilt angle) of the workpiece surface. It is hard to be affected by fluctuations. In addition, the color discrimination type photoelectric switch determines the workpiece based on the color of the workpiece surface, and is affected by variations in the reflectance of the workpiece surface, variations in the distance to the workpiece, and variations in the workpiece surface tilt (tilt angle). It is difficult to receive.

A conventional photoelectric switch of a color discrimination system includes three light emitting elements that respectively generate red, green, and blue detection lights, and one light receiving element that receives reflected light and generates a light reception signal (for example, a patent). Literatures 1-4). In this type of photoelectric switch, for example, the ratio r _k of the light reception amount levels of the three colors based on the light reception amount levels R _k , G _k , and B _k of the three colors obtained by sequentially lighting the light emitting elements in time division. _{= R k / M k, g} k = G k / M k, represents a color by bk ₌ B _k / _M k (OR _{M k = R k + G k} + B k of the light-receiving amount), receiving acquired during the work determination It is determined whether or not the quantity level ratios r ₁ , g ₁ , b ₁ match the pre-registered received light quantity level ratios r ₀ , g ₀ , b ₀ . Specifically, by comparing the ratio of the received light amount level of each color with the ratio of the received light amount level of the reference color, the degree of coincidence of the two color information is obtained, and by comparing this degree of coincidence with the determination threshold value, the work determination is performed. Done.

  The received light level of the reference color is determined based on the received light level of each color acquired at the timing designated by the user. For example, a maximum value and a minimum value are obtained for each color component based on a plurality of received light amount levels or a ratio of received light amount levels acquired within a predetermined period, and an intermediate value between the maximum value and the minimum value is the received light of the reference color It is specified as the ratio of the light level or the light receiving level.

JP 2000-112440 A Japanese Patent Laid-Open No. 2000-121441 JP 2005-127869 A JP 2005-291748 A

  The conventional photoelectric switch described above uses color matching to determine color information, which is usually represented by three parameters, using a single parameter called matching, and therefore discriminates based on the amount of received light and a threshold value. It can be handled in the same way as a light receiving type photoelectric switch, and is easy to set. On the other hand, when detecting a label affixed to a workpiece or a component assembled to a workpiece, a conventional photoelectric switch obtains a color difference from a reference color. Determine that it exists. Also, when detecting a registration mark indicating a cutting position of a sheet-like member, a label applying position, etc., if the color difference from the reference color is equal to or higher than a certain level, it is determined that the registration mark exists. The color difference is obtained from the degree of coincidence and the upper limit value, and the color difference is 0 when the color information completely matches the reference color.

  In a photoelectric switch having an objective lens for condensing detection light in a detection region, a part of the detection light may be reflected by the objective lens and received as return light by the light receiving element without being emitted from the objective lens. . Also, photoelectric switches equipped with an optical fiber cable that transmits detection light from the main body to the head while transmitting reflected light from the detection area from the head to the main body are detected due to defects in the optical fiber such as flaws. There is a case where part of the light is mixed into the optical fiber for reflected light transmission and is received as return light by the light receiving element without being emitted from the head portion.

  In the conventional photoelectric switch of the color discrimination method, the color information is acquired by comparing the amount of received light of each color. For this reason, there is a problem that the received light amount ratio changes due to the influence of the return light, and the color of the workpiece cannot be correctly identified. In particular, when a workpiece having a low reflectance is a detection target, the amount of light reflected from the workpiece is small, and thus the ratio of the amount of received light greatly changes due to the return light.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a photoelectric switch that can suppress a decrease in color discrimination sensitivity. In particular, it is an object of the present invention to provide a photoelectric switch that can suppress a decrease in color discrimination sensitivity due to return light even when a workpiece with low reflectance is a detection target.

  The photoelectric switch according to the first aspect of the present invention includes a light projecting unit that projects detection light corresponding to two or more specific wavelengths toward a detection region, and receives reflected light from the detection region as a light reception signal. A light receiving means for converting, a correction instruction receiving means for receiving a correction instruction, a light receiving signal in accordance with the correction instruction, a return light quantity acquiring means for specifying a received light quantity for each specific wavelength as a return light quantity, and a return light quantity Based on the return light correction unit that corrects the light reception signal and the light reception signal corrected by the return light correction unit, the color information is obtained by comparing the light reception amounts of at least two specific wavelengths. Information acquisition means, reference color acquisition instruction reception means for receiving a reference color acquisition instruction, and a reference color that designates the color information acquired by the color information acquisition means according to the reference color acquisition instruction as a reference color A matching degree calculating means for comparing the color information sequentially obtained by the color information obtaining means with the reference color to obtain a matching degree, and comparing the matching degree with a predetermined determination threshold value. Detection signal output means for performing workpiece determination and outputting a detection signal based on the result of the workpiece determination.

  According to such a configuration, since the light reception signal is corrected based on the return light amount acquired in accordance with the correction instruction, a change in the light reception amount due to the return light can be suppressed. Therefore, when detecting a label, an assembly part, a registration mark, or the like on the workpiece, the color of the workpiece can be correctly identified, and a decrease in color discrimination sensitivity due to return light can be suppressed. In particular, since the color of the workpiece is correctly determined regardless of the amount of reflected light from the workpiece, even when a workpiece with low reflectance is targeted for detection, it is possible to suppress a decrease in color discrimination sensitivity due to return light. it can.

  A photoelectric switch according to a second aspect of the present invention, in addition to the above configuration, emits the detection light toward a detection region, and a main body having a light emitting diode that generates the detection light and a photodiode that generates the light reception signal. On the other hand, a head part to which the reflected light from the detection area is incident and an optical fiber cable for transmitting the detection light and the reflected light between the main body part and the head part are provided to transmit the detection light. An end portion of the optical fiber and an end portion of the optical fiber that transmits the reflected light are arranged adjacent to each other in the head portion.

  According to such a configuration, due to the malfunction of the optical fiber, a part of the detection light is mixed in the reflected-light transmission optical fiber in the head portion, and is received as return light by the photodiode without being emitted from the head portion. Even in this case, it is possible to suppress a decrease in color discrimination sensitivity due to return light.

  In addition to the above configuration, the photoelectric switch according to the third aspect of the present invention is an objective lens that is detachably attached to the head unit and condenses the detection light emitted from the end face of the optical fiber cable on the detection region. It is configured with.

  According to such a configuration, even when a part of the detection light is reflected by the objective lens and is received as return light by the photodiode without being emitted from the objective lens, the color discrimination sensitivity by the return light. Can be suppressed. Further, even if the optical characteristics change by replacing the objective lens, it is possible to suppress a decrease in color discrimination sensitivity due to the return light by acquiring the return light amount and correcting the light reception signal.

  A photoelectric switch according to a fourth aspect of the present invention includes, in addition to the above configuration, the main body portion having a fiber connection portion to which the optical fiber cable is detachably connected, and an end of an optical fiber that transmits the detection light. And an end portion of the optical fiber that transmits the reflected light are arranged in parallel in the fiber connection portion.

  According to such a configuration, even if the optical characteristics are changed by replacing the head unit or the optical fiber cable, the color discrimination by the return light is performed by acquiring the return light amount and correcting the light reception signal. A decrease in sensitivity can be suppressed.

  A photoelectric switch according to a fifth aspect of the present invention includes, in addition to the above configuration, a light projection amount control unit that controls a light projection amount of the detection light based on the light reception signal, and the return light correction unit includes the light projection amount. The return light amount is adjusted in accordance with the received light amount, and the received light signal is corrected based on the adjusted return light amount. According to such a configuration, since the return light amount is adjusted according to the light projection amount, erroneous detection due to the return light can be reduced even when the light projection amount of the detection light changes.

  A photoelectric switch according to a sixth aspect of the present invention includes, in addition to the above configuration, gain control means for controlling the gain of an amplifier that amplifies the light reception signal based on the light reception signal, and the return light correction means includes The return light amount is adjusted according to the gain, and the received light signal is corrected based on the adjusted return light amount. According to such a configuration, since the amount of return light is adjusted according to the gain, erroneous detection due to the return light can be reduced even when the gain of the amplifier changes.

  In the photoelectric switch according to the seventh aspect of the present invention, in addition to the above-described configuration, the color information acquisition unit is configured to determine a received light amount of each color component with respect to a sum of a received light amount of a red component, a received light amount of a green component, and a received light amount of a blue component. It is configured to obtain color information including a ratio. According to such a configuration, the change in the amount of received light is suppressed for each color component, so that erroneous detection due to return light can be reduced.

  In the photoelectric switch according to the eighth aspect of the present invention, in addition to the above configuration, the return light correction unit corrects the light reception signal by subtracting the return light amount from the light reception amount for each specific wavelength. Composed. According to such a configuration, it is possible to reduce erroneous detection due to return light without complicating calculation processing for correction.

  The photoelectric switch according to the ninth aspect of the present invention includes a coincidence degree display means for displaying the coincidence degree in addition to the above structure. According to such a configuration, since the workpiece is determined by comparing the degree of coincidence with the determination threshold, the workpiece determination parameter is only the determination threshold, and the specification of the parameter can be simplified.

  A photoelectric switch according to a tenth aspect of the present invention includes a determination threshold value input unit that receives an input of the determination threshold value in addition to the above configuration. According to such a configuration, the determination threshold can be arbitrarily designated.

  In the photoelectric switch according to the present invention, since the change in the amount of received light due to the return light is suppressed, it is possible to suppress a decrease in color discrimination sensitivity. In particular, since the color of the workpiece is correctly determined regardless of the amount of reflected light from the workpiece, even when a workpiece with low reflectance is targeted for detection, it is possible to suppress a decrease in color discrimination sensitivity due to return light. it can.

It is the perspective view which showed one structural example of the photoelectric switch 1 by embodiment of this invention. It is sectional drawing by the vertical surface of the head part 3 of FIG. It is sectional drawing by the AA cutting line of the head part 3 of FIG. It is the top view which showed the main-body part 10 of FIG. It is sectional drawing by the B1-B1 cutting line of the main-body part 10 of FIG. It is sectional drawing by the B2-B2 cutting line of the main-body part 10 of FIG. It is the perspective view which expanded and showed the main-body part 10 of FIG. It is the perspective view which expanded and showed the optical module 42 of FIG. It is the perspective view which expanded and showed the light projection module 50 of FIG. It is the figure which showed the structural example of the fiber connection part 18 of the main-body part 10 of FIG. It is the perspective view which expanded and showed the clamp module 70 of FIG. It is the figure which showed the operation example of the clamp module 70 of FIG. FIG. 5 is a block diagram illustrating an example of a functional configuration in the main body unit 10 of FIG. 4. FIG. 14 is a block diagram illustrating a configuration example of a main control unit 100 in FIG. 13. It is the figure which showed the other structural example of the head part 3 and the optical fiber cable.

  Embodiments of the present invention will be described below with reference to the drawings. In this specification, for the sake of convenience, the direction of the light projecting / receiving axis of the head portion is assumed to be the vertical direction (vertical direction), and the direction of the light projecting / receiving axis of the main body portion is assumed to be the front-rear direction. It is not intended to limit.

<Photoelectric switch 1>
FIG. 1 is a perspective view showing a configuration example of a photoelectric switch 1 according to an embodiment of the present invention, and shows a color discrimination type photoelectric switch 1. The photoelectric switch 1 is a detection device that projects detection light DL, receives reflected light from a detection region including the workpiece W, performs workpiece determination, and generates a detection signal based on the result of workpiece determination. The workpiece determination is performed by determining the color of the workpiece surface, and a detection signal indicating whether the workpiece W is acceptable or not, the presence / absence of the workpiece W, etc. is output.

  The photoelectric switch 1 includes a main body 10 having a light source for light projection, a light receiving circuit, and the like, an optical fiber cable 2 that transmits the detection light DL and reflected light from the detection region, and emits the detection light DL toward the detection region. On the other hand, the head unit 3 is configured to receive the reflected light from the detection region. The head unit 3 can be installed at a position separated from the main body unit 10. The head unit 3 and the optical fiber cable 2 are detachable from the main body unit 10.

  The main body 10 includes an indicator lamp 11, operation keys 12, and a wiring cable 14. The indicator lamp 11 is an LED (Light Emitting Diode) indicator that is turned on according to the result of the work determination, and is disposed on the upper surface of the casing of the main body 10. The operation key 12 is a push-type set key used when designating a reference color for workpiece determination, and is disposed on the upper surface of the casing of the main body unit 10.

  The wiring cable 14 includes a power cable for supplying power to the circuit elements in the main body 10 and a signal cable for transmitting control signals and detection signals. The lead-out portion of the wiring cable 14 is arranged at the corner portion (corner) of the three surfaces of the housing rear surface, bottom surface (lower surface), and left side surface of the main body unit 10. A mounting hole 13 provided on the side surface of the housing of the main body 10 is a screw hole for fixing the main body 10 to factory equipment or a building.

  The optical fiber cable 2 is a transmission line that transmits the detection light DL and the reflected light between the main body unit 10 and the head unit 3, and an optical fiber 2a for transmitting the detection light DL from the main body unit 10 to the head unit 3. It consists of an optical fiber 2 b for transmitting reflected light from the head unit 3 to the main body unit 10. The optical fiber cable 2 is a parallel type optical fiber cable in which an optical fiber 2a and an optical fiber 2b are arranged side by side.

  A connector portion 21 is provided at the end of the optical fiber cable 2 on the main body side. The connector part 21 is a connection part for detachably connecting the optical fiber cable 2 to the main body part 10, and is made of a member common to the optical fiber 2a and the optical fiber 2b. The connector portion 21 is mounted so as to protrude forward from the front surface of the housing of the main body portion 10. The end of the optical fiber cable 2 on the main body side is fixed to the main body 10 with the optical fiber 2a and the optical fiber 2b being arranged in the vertical direction in this order.

  The outer diameters of the optical fiber 2a and the optical fiber 2b are set to any of Φ1.3 mm to Φ1.0 mm, and the apparent outer diameter of the optical fiber 2a and the optical fiber 2b is Φ2.2 mm by the connector unit 21. It has become. When the outer diameters of the optical fiber 2a and the optical fiber 2b of the optical fiber cable 2 are set to Φ2.2 mm, the ends of the optical fiber 2a and the optical fiber 2b of the optical fiber cable 2 are not provided without providing the connector portion 21. The part can be detachably connected to the main body part 10.

  The head unit 3 is a light projecting / receiving unit, and an end of the optical fiber cable 2 is disposed in the head unit 3 and emits the detection light DL transmitted through the optical fiber 2a downward. The head portion 3 has a bolt shape, is disposed with the cylindrical barrel portion 32 facing downward, and the optical fiber cable 2 is pulled out horizontally from the fiber cable holding portion 31. The end of the optical fiber cable 2 on the head part side is fixed to the head part 3 with the optical fiber 2a and the optical fiber 2b adjacent to each other in the horizontal direction.

  A lens unit 33 is detachably attached to the head unit 3. The lens unit 33 is composed of a cylindrical member having an objective lens for condensing the detection light DL emitted from the end face of the optical fiber 2 a in the detection region, and is attached to the lens barrel portion 32. By replacing the lens unit 33, the measurement range, focal length, projection spot size (spot diameter), and the like can be changed.

<Head 3>
FIG. 2 is a cross-sectional view showing a cut surface when the head unit 3 of FIG. 1 is cut along a vertical plane including the optical axis of the objective lens 34. FIG. 3 is a cross-sectional view showing a cut surface when the head portion 3 of FIG. 2 is cut along an AA cutting line. FIG. 3 shows a case where the cut surface is viewed from the direction indicated by the arrow.

  The head housing 30 of the head unit 3 includes a fiber cable holding unit 31 and a lens barrel unit 32. The optical fiber 2 a is held horizontally in the fiber cable holding unit 31. The end portion 22 on the head portion side of the optical fiber cable 2 is held in the lens barrel portion 32 with the end face of the optical fiber 2a facing downward. The end 22 is fixed in the lens barrel 32 via a holding member 321. That is, the optical fibers 2 a and 2 b of the optical fiber cable 2 are bent at right angles in the head portion 3.

  The end portion 22 on the head portion side of the optical fiber cable 2 is composed of an end portion of the optical fiber 2a and an end portion of the optical fiber 2b, and the end portion of the optical fiber 2a and the end portion of the optical fiber 2b are adjacent to each other. It is arranged in the lens barrel part 32 of the housing 30. The end 22 includes a core 221 that propagates light and a clad 222 that surrounds the core 221.

  As described above, the optical fiber 2 a and the optical fiber 2 b are arranged in the head housing 30 with the clads 222 being circumscribed. For this reason, if there is a defect such as a flaw, a part of the detection light DL is mixed from the optical fiber 2a to the optical fiber 2b side and is received as return light by the light receiving element without being emitted from the head unit 3. There is.

  The objective lens 34 of the lens unit 33 is disposed so as to face the end face of the optical fiber 2a. By moving the lens unit 33 with respect to the head housing 30, the focal length, the spot diameter, and the like can be adjusted.

  In the photoelectric switch 1 having such an objective lens 34, a part of the detection light DL is reflected by the inner surface of the objective lens 34 and may be received as return light by the light receiving element without being emitted from the objective lens 34. is there. In the photoelectric switch 1 according to the present embodiment, in order to suppress the erroneous detection due to the return light described above, the received light amount of each color is acquired at the timing when the user instructs correction, and the received light amount at the time of normal detection is obtained using the received light amount. Processing for correcting the amount is performed.

<Main body 10>
FIG. 4 is a plan view showing the main body 10 of FIG. In the figure, (a) shows the front surface of the main body 10 and (b) shows the right side of the main body 10. FIG. 5 is a cross-sectional view showing a cut surface when the main body 10 of FIG. 4 is cut along a B1-B1 cutting line. FIG. 6 is a cross-sectional view showing a cut surface when the main body 10 of FIG. 4 is cut along a B2-B2 cutting line. 5 and 6 show the case where the cut surface is viewed from the direction indicated by the arrow. FIG. 7 is an exploded perspective view of the main body 10 of FIG. FIG. 8 is an exploded perspective view of the optical module 42 of FIG. FIG. 9 is an exploded perspective view of the light projecting module 50 of FIG.

  The photoelectric switch 1 includes a main body casing 15, operation keys 16, an insulating film 41, an optical module 42, a main substrate 43, and a shield sheet 44. The body housing 15 is a rectangular parallelepiped casing for housing circuit elements, optical components, and the like, and includes a housing portion 15a and a body cover 15b.

  The accommodating portion 15a is a box having an opening on the right side, and the insulating film 41, the optical module 42, the main substrate 43, and the shield sheet 44 are accommodated in this order. The main body cover 15b is a side plate that closes the opening of the housing portion 15a, and is attached to the housing portion 15a. The accommodating portion 15a and the main body cover 15b are formed of a high thermal conductivity material. The high thermal conductivity material is a material having high thermal conductivity and is excellent in heat dissipation.

  For example, the accommodating portion 15a and the main body cover 15b are formed using a metal having a higher thermal conductivity than a resin or the like. In the photoelectric switch 1, a main body housing 15 made of zinc die casting is used. The indicator lamp 11, the operation keys 12 and 16, the mounting hole 13, the display panel 17, the fiber connection portion 18, and a clamp module 70 described later are provided in the housing portion 15 a of the main body portion 10.

  The operation key 16 is a push-type direction key used when designating a threshold value for workpiece determination, and includes an up key and a down key. The numerical value can be incremented by operating the up key, and the numerical value can be decremented by operating the down key. The operation key 16 is disposed on the back surface of the housing portion 15a.

  The display panel 17 is a display device that displays a threshold value and a degree of coincidence for workpiece determination, and is disposed on the back surface of the housing portion 15a. For example, the display panel 17 is a 7-segment display. The display panel 17 may be an active matrix drive type display device such as an LCD (Liquid Crystal Display).

  The fiber connection portion 18 is a fiber cable attachment / detachment portion to which the optical fiber cable 2 is detachably connected, and is disposed in the clamp module 70. The end portion of the optical fiber 2a and the end portion of the optical fiber 2b are arranged in parallel in the fiber connection portion 18 and are separated from each other in the vertical direction.

  The insulating film 41 is a sheet-like member that has electrical insulation and is disposed along the side wall of the housing portion 15a. The insulating film 41 is a resin film that electrically insulates the circuit element from the main body casing 15 and is disposed in close contact with the left side wall.

  The insulating film 41 preferably has a high thermal conductivity, but if the thickness is less than about 0.5 mm, the thermal resistance is low even if the thermal conductivity is not particularly considered, and more preferably the thickness is about 0.1 mm. If there is, heat can be radiated to the main body casing 15 via the insulating film 41. In addition, it can replace with the insulating film 41 and can interpose an insulator with high heat conductivity and insulation, and can also make heat dissipation and electrical insulation compatible.

<Optical module 42>
The optical module 42 includes an optical base frame 420, a light projecting module 50, a light receiving substrate 60, a PD unit 61, and a glass plate 62. The optical base frame 420 is a support member that supports the optical component and the circuit board.

<Light Emitting Module 50>
The light projecting module 50 includes a light projecting substrate 51, a light emitting element 52, a light projecting substrate holder 53, a heat dissipation sheet 54, an adjustment spacer 55, a fiber holder 56, a glass fiber 57, a cushion material 58, and a fiber presser 59.

  The light emitting element 52 is a light source for projection that generates the detection light DL. The light emitting element 52 is an LED (Light Emitting Diode) that generates white light including two or more color components having different hues as the detection light DL. The light emitting element 52 includes a rectangular semiconductor chip, and is disposed on the light projecting substrate 51. Surface mounted. The light projecting board 51 is a circuit board provided with circuit elements for light projection. The light projecting substrate 51 is arranged with the light emitting surface of the light emitting element 52 facing forward.

  The light emitting element 52 is a white LED that generates white light by mixing light of two or more colors having a complementary color relationship. For example, the light emitting element 52 includes a stacked body in which a semiconductor element layer that emits blue light and a phosphor layer having a phosphor are stacked. The phosphor layer is fixed with a translucent resin or glass, and the phosphor is excited by the radiation of the semiconductor element layer and emits light having a longer wavelength than blue light, for example, yellow light. .

  The light projecting substrate holder 53 is a heat sink member for holding the light projecting substrate 51 and dissipating heat generated in the circuit elements such as the light emitting elements 52, and is made of a highly thermally conductive material. For example, it is formed of a metal material such as zinc die casting. The light projecting substrate holder 53 is disposed so as to face the front surface of the light projecting substrate 51.

  The heat radiating sheet 54 is a plate-like member made of a highly heat conductive resin, and is disposed between the side wall of the housing portion 15 a and the light projecting substrate holder 53. For example, the heat dissipation sheet 54 is formed of silicone rubber. When the light projecting substrate holder 53 is made of metal, the heat dissipation sheet 54 preferably has electrical insulation. In addition, when not providing the insulating film 41, it is preferable that the thermal radiation sheet 54 has electrical insulation.

  The heat radiating sheet 54 is preferably formed of a member having high adhesion followability to uneven surfaces and curved surfaces such as rubber, elastomer, and gel-like body, and the insulating film 41 and the light projecting substrate holder disposed on the side wall of the housing portion 15a. Adheres to 53 and realizes high heat dissipation. For example, the heat radiating sheet 54 is made of electrically insulating and thermally conductive silicone or acrylic resin rubber, elastomer, or gel. When the insulating film 41 is not provided, the heat dissipation sheet 54 is in close contact with the side wall of the housing portion 15 a and the light projecting substrate holder 53.

  The glass fiber 57 is a light guiding optical component that guides the detection light DL emitted from the light emitting element 52 to the end of the optical fiber cable 2 on the main body side, and is made of a glass optical fiber. The glass fiber 57 has a cylindrical shape extending in the front-rear direction, and is disposed in a state where the rear end surface is opposed to the light emitting surface of the light emitting element 52 and the front end surface is opposed to the end surface of the optical fiber 2a. Moreover, the glass fiber 57 is arrange | positioned coaxially with the optical fiber 2a.

  The fiber holder 56 is a holding member that holds the glass fiber 57 and is fixed to the light projecting substrate holder 53. The fiber retainer 59 is attached to the fiber holder 56 with a cushion material 58 sandwiched between the fiber retainer 59 and the glass fiber 57. The adjustment spacer 55 is a sheet-like member disposed between the light projecting substrate holder 53 and the fiber holder 56.

<Light receiving module>
The PD unit 61 is a light receiving element unit that selectively receives reflected light from the detection region corresponding to two or more specific wavelengths and generates two or more received light signals respectively corresponding to the received light amounts for the specific wavelengths. It is composed of two or more PDs (Photo Diodes). The PD unit 61 is a multi-division PD unit in which PDs are two-dimensionally arranged on the light receiving substrate 60. For example, each PD is arranged in a 12 × 24 matrix.

  The light receiving substrate 60 is a circuit substrate provided with a light receiving circuit element. The light receiving substrate 60 is fixed to the optical base frame 420 with the light receiving surface of the PD unit 61 facing forward.

  The glass plate 62 is a butting protection member for preventing a collision between the end of the optical fiber cable 2 and the light receiving surface of the PD unit 61, and is a transparent plate member made of glass that transmits reflected light from the detection region. Consists of. The glass plate 62 is arranged in a state where the back surface is opposed to the light receiving surface of the PD unit 61 and the front surface is opposed to the end surface of the optical fiber 2b. The optical components and circuit elements for receiving light are arranged below the optical components and circuit elements for projecting light.

  The main board 43 is a circuit board provided with circuit elements such as an arithmetic circuit. The main board 43 is attached to the optical base frame 420 with the circuit forming surface facing the main body cover 15b. Only one surface of the main substrate 43 may be a circuit formation surface, or both surfaces may be circuit formation surfaces.

  The shield sheet 44 is a sheet-like shield member having electrostatic, magnetic or electromagnetic shielding performance. The shield sheet 44 is a sheet that electrostatically, magnetically, or electromagnetically insulates circuit elements in the main body casing 15 and is disposed between the main board 43 and the main body cover 15b. The shield sheet 44 may be covered with a resinous film having electrical insulation.

<Fiber connection 18>
FIG. 10 is a diagram illustrating a configuration example of the fiber connection unit 18 of the main body unit 10 of FIG. (A) in the figure shows the front surface of the main body 10 to which the connector portion 21 of the optical fiber cable 2 is connected, and (b) shows the case where the main body 10 is cut along a CC cutting line. A cut surface is shown.

  The connector unit 21 includes a fiber holder unit 211 that holds the optical fibers 2 a and 2 b, and a guide unit 212 that guides the end 23 on the main body side of the optical fiber cable 2 into the main body housing 15. The optical fibers 2a and 2b both extend in a straight line in the front-rear direction, are spaced apart from each other in the vertical direction, and are held by the connector portion 21 in a parallel state.

  The guide part 212 includes a light projection guide part 212 a extending in the front-rear direction along the optical fiber 2 a and a light-receiving guide part 212 b extending in the front-rear direction along the optical fiber 2 b, and is attached to the fiber holder part 211. .

  Such a connector portion 21 is attached to and detached from the fiber connection portion 18 in the front-rear direction. The clamp module 70 is a slide type locking mechanism for fixing the connector portion 21 so that the connector portion 21 does not fall off the main body portion 10, and is attached to the main body housing 15.

  The glass fiber 57 of the light projecting module 50 is disposed between the light emitting element 52 and the end 23 of the optical fiber 2a. The rear end surface of the glass fiber 57 is slightly separated from the light emitting surface of the light emitting element 52. The front end face of the glass fiber 57 is also slightly separated from the end face of the optical fiber 2a. In addition, you may comprise so that the front-end surface of the glass fiber 57 and the end surface of the optical fiber 2a may contact | abut.

  By using such a glass fiber 57 to guide the detection light DL to the optical fiber 2a, transmission loss can be reduced as compared with the case of using an optical lens. In addition, by using a glass optical fiber, it is possible to suppress deformation due to heat from the light emitting element 52 as compared to the case of using a resin optical fiber.

  The glass plate 62 of the light receiving module is disposed between the PD unit 61 and the end 23 of the optical fiber 2b. The back surface of the glass plate 62 is slightly separated from the light receiving surface of the PD unit 61. The front surface of the glass plate 62 is also slightly separated from the end surface of the optical fiber 2b.

<Clamp module 70>
FIG. 11 is an exploded perspective view of the clamp module 70 of FIG. FIG. 12 is a diagram illustrating an operation example of the clamp module 70 of FIG. (A) in the drawing shows a case where the clamp module 70 is in a locked state, and (b) shows a case where the clamp module 70 is in an open state.

  The clamp module 70 includes a clamp case 71, a slide case 72, a seal holder 73, a front packing 74, a clamp case packing 75, a fiber holder 76, a holder holder 77, a holder guide 78, a gear lever 79, a bush packing 80, a gear 81, and a cam gear. 82.

  The clamp case 71 is a member that accommodates the fiber holder 76, the holder retainer 77, the holder guide 78, the gear 81, and the cam gear 82. The two through holes in which the guide portions 212 of the connector portion 21 are disposed and the seal retainer 73 are disposed. A seal-pressing arrangement portion, a gear lever accommodating portion for accommodating the gear lever 79 rotatably, and the like are formed.

  The slide case 72 is attached to the clamp case 71 so as to be movable in the vertical direction, and rotates the gear lever 79 around the rotation axis extending in the horizontal direction so as to be interlocked with the movement in the vertical direction. The gear lever 79 passes through the gear 81 and rotates the gear 81 around a rotation axis extending in the left-right direction. An annular bush packing 80 is disposed between the gear lever 79 and the clamp case 71.

  The fiber holder 76 is a member that holds the distal end portion of the guide portion 212. The holder guide 78 is a plate-like member that guides the movable part of the fiber holder 76 in the vertical direction. The holder presser 77 comes into contact with the cam gear 82 and pushes up the movable portion of the fiber holder 76 so as to interlock with the rotation of the cam gear 82. The cam gear 82 meshes with the gear 81 and moves the holder presser 77 in the vertical direction so as to interlock with the rotation of the gear 81.

  The seal retainer 73 is a plate-like member for fixing the front packing 74 to the clamp case 71, and has two through holes in which the guide portion 212 is disposed. The seal retainer 73 is attached to the front side of the clamp case 71 with the front packing 74 sandwiched therebetween.

  In the clamp case 71, a fiber holder 76, a holder presser 77, a holder guide 78, a gear 81 and a cam gear 82 are accommodated from the back side. The clamp case 71 is fixed to the accommodating portion 15a of the main body housing 15 via the clamp case packing 75 in a state where these members are accommodated.

  The locked state of the clamp module 70 is a state in which the guide portion 212 is fixed to the fiber holder 76 by moving the slide case 72 to the lower locked position. In this locked state, the holder presser 77 is pushed upward by the cam gear 82, whereby the tip end portion of the guide portion 212 is fastened by the fiber holder 76 and fixed to the fiber holder 76.

  On the other hand, the open state of the clamp module 70 is a state in which the guide portion 212 can be removed from the fiber holder 76 by moving the slide case 72 to the upper open position. In this open state, the holder presser 77 is lowered downward in conjunction with the rotation of the cam gear 82, whereby the fiber holder 76 is loosely tightened with respect to the distal end portion of the guide portion 212, and the distal end portion of the guide portion 212 is removed from the fiber holder 76. Is possible.

  By providing such a clamp module 70, the head unit 3 or the optical fiber cable 2 can be easily replaced. Further, since seal members such as the front packing 74, the clamp case packing 75, and the bush packing 80 are disposed in the clamp module 70, it is possible to prevent water and dust from entering the clamp case 71.

  FIG. 13 is a block diagram showing an example of a functional configuration in the main body 10 of FIG. The main unit 10 includes a main control unit 100, a light projecting drive unit 101, a light emitting element 52, a color filter 102, a PD unit 61, an amplifier unit 103, a memory 104, a power supply unit 105, an input / output unit 106, a display unit 107, and an operation. The unit 108 is configured.

  The main control unit 100 controls light projection and reception, and performs workpiece determination based on the light reception signal. The light projecting drive unit 101 drives the light emitting element 52 based on an instruction from the main control unit 100. For example, the main control unit 100 controls the light projection amount instructed to the light projection drive unit 101. The light projection amount is controlled based on the amount of light received from the light receiving element of the PD unit 61 so that the amount of received light is within a certain range.

  In the case of a workpiece having a high reflectance, the amount of received light is relatively large. Therefore, the main control unit 100 instructs the light projecting drive unit 101 on the basis of the amount of received light. On the other hand, since the received light amount is relatively small in the case of a work having a low reflectance, the main control unit 100 instructs the light projecting drive unit 101 on the basis of the received light amount. Further, the light projecting drive unit 101 performs pulse driving of the light emitting element 52 based on the light projection amount instruction and the light projection timing instruction from the main control unit 100. When the light emitting element 52 is pulse-driven, the pulse light emission amount of the light emitting element 52 is measured by a monitor PD (not shown), and the light projecting drive unit 101 is controlled so that the measured pulse light emission amount matches a predetermined target value. May be. In this case, the main control unit 100 can adjust the light emission amount of the light emitting element 52 by adjusting the target value.

  The detection light DL is emitted from the head unit 3 toward the detection region. The reflected light RL from the detection region is incident on the PD unit 61 via the color filter 102. The color filter 102 is an optical component that selectively transmits light of a color component having a specific wavelength according to a two-dimensional position, and is disposed on the light receiving surface of the PD unit 61. In the color filter 102, an R filter region, a G filter region, and a B filter region that selectively transmit any of red light, green light, and blue light are arranged in a matrix. Each of the R filter region, the G filter region, and the B filter region is formed of a minute rectangular region, and is formed in association with a large number of light receiving elements (PD).

  The PD unit 61 receives the reflected light RL and generates a light reception signal. The amplifier unit 103 is an amplifier unit that amplifies a light reception signal input from each light receiving element of the PD unit 61 and outputs the amplified signal to the main control unit 100. The amplifier unit 103 can switch the gain. The light reception signal is amplified for each color component of a specific wavelength and output to the main control unit 100. Similarly to the adjustment of the light emission amount of the light emitting element 52 by the main control unit 100, the gain of the amplifier unit 103 is based on the light reception signal indicating the light reception amount from the light receiving element so that the light reception amount is within a certain range. It is controlled by the control unit 100. The main control unit 100 may control both the gain of the amplifier unit 103 and the light emission amount of the light emitting element 52 based on the light reception signal.

  The memory 104 holds a work determination threshold value, reference color information, and the like. The power supply unit 105 is connected to an external device such as a controller via the wiring cable 14 and supplies DC power to the main control unit 100 and the light projecting drive unit 101 based on the control of the main control unit 100. The input / output unit 106 is connected to an external device such as a controller via the wiring cable 14, receives a control signal, outputs the control signal to the main control unit 100, and outputs a detection signal input from the main control unit 100 to the external device. Send.

  Based on the control of the main control unit 100, the display unit 107 displays a threshold value for work determination, a matching degree, a color difference, and the like on the display panel 17. The operation unit 108 generates an operation signal based on the pressing operation of the operation keys 12 and 16 and outputs the operation signal to the main control unit 100.

<Main control unit 100>
FIG. 14 is a block diagram illustrating a configuration example of the main control unit 100 of FIG. The main control unit 100 includes a light projection amount control unit 110, a gain control unit 111, a color information acquisition unit 112, a reference color acquisition unit 113, a coincidence degree calculation unit 114, a detection signal output unit 115, a correction instruction reception unit 116, and a return light amount. The acquisition unit 117, the return light amount storage unit 118, the return light correction unit 119, the parameter specification unit 120, the determination threshold storage unit 121, and the reference color capture instruction reception unit 122 are configured.

  The light projection amount control unit 110 controls the light projection drive unit 101 based on the light reception signal input from the amplifier unit 103 and adjusts the light projection amount of the detection light DL. For example, when the amount of reflected light RL received exceeds a certain level, the amount of light emitted is reduced. On the other hand, when the amount of reflected light RL received below the certain level, the amount of emitted light is increased to return to the original state. Is done.

  The gain control unit 111 adjusts the gain of the amplifier unit 103 based on the light reception signal input from the amplifier unit 103. For example, when the amount of reflected light RL received exceeds a certain level, the gain of the amplifier unit 103 is decreased. On the other hand, when the amount of reflected light RL received below the certain level, the gain of the amplifier 103 is increased. Control to return to the original state is performed. Such control of the light projection amount and the gain is performed based on the received light amount of RGB. Alternatively, it is performed based on parameters obtained by combining the received light amounts of RGB.

The color information acquisition unit 112 acquires color information based on two or more received light signals respectively corresponding to two or more specific wavelengths, and outputs the color information to the reference color acquisition unit 113 and the matching degree calculation unit 114. The acquired color information is acquired by comparing the received light amounts of at least two specific wavelengths. For example, the color information acquisition unit 112 acquires color information including the ratio of the received light amount of each color component to the sum of the received light amount of the red component, the received light amount of the green component, and the received light amount of the blue component. Specifically, the received light amount level of red light is R ₁ , the received light amount level of green light is G ₁ , the received light amount level of blue light is B _1, and the sum of received light amounts is M _k = R _k + G _k + B _k. Then, a set (r ₁ , g ₁ , b) using the ratios r _k = R _k / M _k , g _k = G _k / M _k , and b _k = B _k / M _k of the three light reception levels. _The color is expressed by ₁ ). The color information (r ₁ , g ₁ , b ₁ ) is periodically and repeatedly acquired.

The reference color capture instruction receiving unit 122 receives a reference color capture instruction based on an operation signal from the operation unit 108 and instructs the color information acquisition unit 112 to capture color information. For example, when a label or registration mark is detected, the reference color is instructed in the absence of the label or registration mark. The reference color acquisition unit 113 specifies the color information (r ₀ , g ₀ , b ₀ ) acquired by the color information acquisition unit 112 in accordance with the reference color acquisition instruction as a reference color.

The coincidence degree calculation unit 114 uses the color information (r ₁ , g ₁ , b ₁ ) acquired by the color information acquisition unit 112 as the color information (r ₀ , g ₀ , b ₀ ), the degree of coincidence C between the two color information is calculated and output to the detection signal output unit 115. The degree of coincidence C is a parameter indicating the degree of color coincidence, and it is quantitatively evaluated how much the color to be compared is similar to the color registered as a reference for work determination.

  For example, the degree of coincidence C is expressed using an integer of 0 or more and 999 or less. In this case, the upper limit of the matching degree C is 999, and the matching degree C is 999 if the color to be compared completely matches the reference color. The degree of coincidence C may be expressed using an integer of 1 to 1000. In this case, the upper limit of the matching degree C is 1000, and the matching degree C is 1000 if the color to be compared completely matches the reference color.

The display unit 107 displays the matching degree C calculated by the matching degree calculation unit 114 on the display panel 17. In addition, as the color information, a set of r _k , g _k , and b _k (r _k , g _k , b _k ), which is the ratio of the received light amount level of each color, has been illustrated. Not limited to. For example, a combination (R _k , G _k , B _k ) of a received light level of red light, a received light level of green light, and a received light level of blue light may be used as color information. Further, the color information is not limited to the RGB color system, and a set of color component values based on the color system such as Lab may be used as the color information.

  The detection signal output unit 115 compares the degree of coincidence C calculated by the degree of coincidence calculation unit 114 with a predetermined determination threshold Cd to perform work determination, and outputs a detection signal based on the result of the work determination. The detection signal is transmitted to an external device via the input / output unit 106. In the operation mode, every time color information is newly acquired, the degree of coincidence C is calculated, and the work determination is performed. For example, when the degree of coincidence C falls below the determination threshold Cd, the detection signal of the photoelectric switch 1 transitions to an on state. On the other hand, when the degree of coincidence C is equal to or higher than the determination threshold Cd, the detection signal of the photoelectric switch 1 transitions to an off state.

  The correction instruction receiving unit 116 receives a correction instruction based on the operation signal from the operation unit 108 and instructs the return light amount acquisition unit 117 to capture the received light signal. For example, the correction instruction accepting unit 116 instructs the capture time of the received light signal by the return light quantity acquisition unit 117, and instructs the capture timing and the capture period as the capture time, for example. If the detection light DL is being projected from the light projecting module 50 and there is no object on the workpiece W or the background, the reflected light RL from the detection area is not received by the PD unit 61 and is not emitted from the detection area. The received light amount level of the reflected light RL is ideally 0. However, in the state where the detection light DL is projected from the light projecting module 50, the received light level in the PD unit 61 returns due to the influence of the return light even though there is no object on the workpiece W or the background. The level corresponds to the amount of light.

  Therefore, for example, the correction instruction is accepted and the received light signal is taken in the absence of the workpiece W such as changing the orientation of the head unit 3. The light projection amount of the detection light DL is adjusted based on the light reception signal by the light projection amount control unit 110. Typically, if there is no object on the workpiece W or the background, detection from the light projection module 50 is typically performed. The light emission amount of the light DL is adjusted to the maximum light emission amount within the range adjustable by the light emission amount control unit 110. However, in the case of an optical system with a large return light amount, the light projection amount of the detection light DL is not necessarily adjusted to the maximum light projection amount by the light projection amount control unit 110. Further, the gain of the amplifier unit 103 is adjusted based on the light reception signal by the gain control unit 111. Typically, if there is no object on the workpiece W or the background, the gain of the amplifier unit 103 is typically The gain is adjusted to the maximum gain within the adjustable range. However, in the case of an optical system with a large amount of return light, the gain of the amplifier unit 103 is not necessarily adjusted to the maximum gain by the gain control unit 111.

  The return light quantity acquisition unit 117 acquires a light reception signal in accordance with the correction instruction from the correction instruction reception unit 116, and designates the light reception quantity for each specific wavelength as the return light quantity. The return light quantity storage unit 118 holds the return light quantity for each specific wavelength.

  The light projection amount of the detection light DL when the return light amount acquisition unit 117 acquires the received light signal in accordance with the correction instruction of the correction instruction reception unit 116 is, for example, the maximum light emission amount within a range adjustable by the light emission amount control unit 110. The light projection amount may be adjusted to a predetermined amount. Alternatively, the light projection amount of the detection light DL when the return light amount acquisition unit 117 acquires the light reception signal in accordance with the correction instruction of the correction instruction reception unit 116 is adjusted by the light emission amount control unit 110 based on the light reception signal. There may be. In this case, for example, the return light amount storage unit 118 holds information related to the received light amount of the detection light DL adjusted by the light projection amount control unit 110 and the return light amount for each specific wavelength. Further, the return light amount may be normalized based on the received light amount of the detection light DL adjusted by the light projection amount control unit 110, and the normalized return light amount may be used as the return light amount in the subsequent processing. In addition, when the return light amount acquisition unit 117 acquires the light reception signal in accordance with the correction instruction from the correction instruction reception unit 116, the light emission amount of the detection light DL is adjusted to the first light emission amount in the first period, In the period, the projection light quantity of the detection light DL is adjusted to the second projection light quantity, the first return light quantity is acquired in the first period, and the second return light quantity is acquired in the second period. . In this case, the return light amount storage unit 118 holds the return light amount for each specific wavelength for each projection light amount of the detection light DL.

  The gain of the amplifier unit 103 when the return light amount acquisition unit 117 acquires the received light signal in accordance with the correction instruction from the correction instruction reception unit 116 is determined in advance, for example, as the maximum gain within the range adjustable by the gain control unit 111. The gain may be adjusted. Alternatively, the gain of the amplifier unit 103 when the return light quantity acquisition unit 117 acquires the light reception signal in accordance with the correction instruction of the correction instruction reception unit 116 is adjusted by the gain control unit 111 based on the light reception signal. Also good. In this case, for example, the return light amount storage unit 118 holds information related to the gain adjusted by the gain control unit 111 and the return light amount for each specific wavelength. Further, when the return light quantity acquisition unit 117 acquires the light reception signal in accordance with the correction instruction from the correction instruction reception unit 116, the gain of the amplifier unit 103 is adjusted to the first gain in the first period, and in the second period. The gain of the amplifier unit 103 may be adjusted to the second gain, and the first return light amount may be acquired in the first period, and the second return light amount may be acquired in the second period. In this case, the return light amount storage unit 118 holds the return light amount for each specific wavelength for each gain of the amplifier unit 103.

  Based on the return light amount stored in the return light amount storage unit 118, the return light correction unit 119 corrects the light reception signal that is sequentially generated according to the current light reception amount. Further, it may be configured to correct the light reception signal sequentially generated according to the current light reception amount based on the return light amount stored in the return light amount storage unit 118 and the information regarding the light reception amount of the detection light DL. Good. For example, the return light correction unit 119 corrects the received light signal by subtracting the returned light amount from the received light amount for each specific wavelength. The color information acquisition unit 112 periodically and repeatedly acquires color information based on the light reception signal corrected by the return light correction unit 119.

If the return light amounts of the three colors are R ₂ , G ₂ , and B ₂ , the corrected received light amount levels are (R ₁ -R ₂ ), (G ₁ -G ₂ ), and (B ₁ -B ₂ ). is there. The received light level of the reference color is (R ₀ -R ₂ ), (G ₀ -G ₂ ), (B ₀ -B ₂ ).

  The return light correction unit 119 adjusts the return light amount according to the projection light amount of the detection light DL adjusted by the projection light amount control unit 110, and corrects the received light signal based on the adjusted return light amount. According to such a configuration, since the return light amount is adjusted according to the light projection amount, erroneous detection due to the return light can be reduced even when the light projection amount of the detection light DL changes.

  The return light correction unit 119 adjusts the return light amount according to the gain of the amplifier unit 103 adjusted by the gain control unit 111, and corrects the received light signal based on the adjusted return light amount. According to such a configuration, since the amount of return light is adjusted according to the gain, erroneous detection due to the return light can be reduced even when the gain of the amplifier unit 103 changes.

  The parameter specifying unit 120 receives input of various parameters including the determination threshold Cd based on the operation signal from the operation unit 108. The determination threshold storage unit 121 holds the determination threshold Cd specified by the parameter specifying unit 120. The user can arbitrarily specify the determination threshold Cd. The detection signal output unit 115 compares the degree of coincidence C with the determination threshold Cd registered in the determination threshold storage unit 121 to perform work determination.

  According to the present embodiment, since the light reception signal is corrected based on the return light amount acquired in accordance with the correction instruction, a change in the light reception amount due to the return light can be suppressed. Accordingly, when detecting a label, an assembly part, a registration mark, or the like on the workpiece W, the color of the workpiece W can be correctly identified, and a decrease in color discrimination sensitivity due to return light can be suppressed. In particular, since the color of the workpiece W is correctly determined regardless of the amount of light reflected from the workpiece W, even when the workpiece W having a low reflectance is targeted for detection, a reduction in color discrimination sensitivity due to return light is suppressed. can do.

  In particular, due to a defect in the optical fiber, a part of the detection light DL is mixed in the reflected light transmission optical fiber 2b in the head unit 3, and is returned to the light receiving element of the PD unit 61 without being emitted from the head unit 3. Even when the light is received as light, it is possible to suppress a decrease in color discrimination sensitivity due to return light. Further, even when a part of the detection light DL is reflected by the objective lens 34 and is received as return light by the light receiving element of the PD unit 61 without being emitted from the objective lens 34, the color discrimination by the return light is performed. A decrease in sensitivity can be suppressed. In addition, even if the optical characteristics change by replacing the objective lens 34, a decrease in color discrimination sensitivity due to the return light can be suppressed by acquiring the return light amount and correcting the light reception signal. .

  Furthermore, even if the optical characteristics are changed by replacing the head unit 3 or the optical fiber cable 2, the return light quantity is acquired and the received light signal is corrected, thereby reducing the color discrimination sensitivity due to the return light. Can be suppressed.

  In the present embodiment, the example in which the optical fiber cable 2 is a parallel cable and is bent at a right angle in the head portion 3 has been described. However, the present invention is not limited to the optical fiber cable 2 or the head portion 3. The configuration is not limited to this. For example, the optical fiber cable 2 may be a coaxial cable in which the optical fibers 2a and 2b are coaxially arranged. Further, the head portion 3 may have a cylindrical shape in which the optical fiber cable 2 is linearly arranged.

  FIG. 15 is a diagram illustrating another configuration example of the head unit 3 and the optical fiber cable 2. (A) in the figure shows a cylindrical head portion 3 extending in the front-rear direction, and (b) shows a cut when the head portion 3 is cut by a vertical plane intersecting with the light projecting / receiving axis in the front-rear direction. A face is shown.

  The optical fiber cable 2 is a coaxial optical fiber cable. The eight optical fibers 2b are arranged so as to surround the optical fiber 2a with the single optical fiber 2a as the center. The head housing 30 of the head unit 3 has a cylindrical shape extending in the front-rear direction. The strand diameter of the optical fiber 2a is about 0.5 mm. On the other hand, the strand diameter of the optical fiber 2b is about 0.265 mm.

In the present embodiment, an example in which the degree of coincidence C is calculated based on the ratios r _k , g _k , and b _k of the received light amount levels of the three colors has been described. The calculation method is not limited to this. The configuration may be such that the degree of coincidence C is obtained based on the ratios r _k , g _k , b _k of the received light amount levels of the three colors and the sum M _{k of the} received light amounts. By using such a degree of coincidence C, not only chromatic work, but also work in which the hue and saturation are similar and only lightness changes greatly, especially achromatic colors having black and white shades. Can be detected correctly.

  Further, in the present embodiment, an example has been described in which the reference color is instructed or the correction color information is instructed based on the pressing operation of the operation key 12. However, the method for instructing the capture of color information is not limited to this. For example, the configuration may be such that the reference color is instructed or the correction color information is instructed based on a trigger signal or a timing signal input from an external device such as a controller. .

  In the present embodiment, an example in which white light including two or more color components having different hues is used as the detection light DL has been described. However, the present invention is not limited to this. . For example, a configuration in which three light emitting elements that respectively generate red, green, and blue detection lights are provided as light sources for light projection, and the respective light emitting elements are sequentially turned on in a time-sharing manner. Moreover, the structure which lights up three light emitting elements of red, green, and blue simultaneously and obtains the white detection light DL may be sufficient.

  In the present embodiment, the example in which the reflected light RL is received using the PD unit 61 has been described, but the present invention does not limit the configuration of the light receiving means. For example, a configuration in which a spectroscope that splits the reflected light RL into three color components and three light receiving elements that receive each color component as light receiving means may be used. Alternatively, when red, green, and blue detection lights are sequentially projected in a time division manner, a configuration in which one light receiving element is provided as a light receiving unit may be used.

DESCRIPTION OF SYMBOLS 1 Photoelectric switch 10 Main body part 11 Indicator lamp 12, 16 Operation key 13 Mounting hole 14 Wiring cable 15 Main body housing | casing 15a Housing | casing part 15b Main body cover 17 Display panel 18 Fiber connection part 2 Optical fiber cable 2a, 2b Optical fiber 21 Connector part 22 End portion 23 on the head portion side of the optical fiber cable 3 End portion on the main body side of the optical fiber cable 3 Head portion 30 Head housing 31 Fiber cable holding portion 32 Lens barrel portion 33 Lens unit 34 Objective lens 41 Insulating film 42 Optical module 43 Main board 44 Shield sheet 420 Optical base frame 50 Light projecting module 51 Light projecting board 52 Light emitting element 53 Light projecting board holder 54 Heat radiating sheet 55 Adjustment spacer 56 Fiber holder 57 Glass fiber 58 Cushion material 59 Fiber retainer 60 Light receiving board 61 P Unit 62 Glass plate 70 Clamp module 100 Main control unit 101 Light projection drive unit 102 Color filter 103 Amplifier unit 104 Memory 105 Power source unit 106 Input / output unit 107 Display unit 108 Operation unit 110 Light emission amount control unit 111 Gain control unit 112 Color information acquisition Unit 113 reference color acquisition unit 114 coincidence calculation unit 115 detection signal output unit 116 correction instruction reception unit 117 return light amount acquisition unit 118 return light amount storage unit 119 return light correction unit 120 parameter specification unit 121 determination threshold storage unit 122 reference color capture Instruction reception part

Claims (10)

A light projecting means for projecting detection light corresponding to two or more specific wavelengths toward the detection region;
A light receiving means for receiving reflected light from the detection region and converting it into a light reception signal;
Correction instruction receiving means for receiving a correction instruction;
Return light quantity acquisition means for acquiring the received light signal according to the correction instruction and designating the received light quantity for each specific wavelength as a return light quantity;
Return light correction means for correcting the light reception signal based on the return light amount;
Based on the light reception signal after correction by the return light correction means, color information acquisition means for acquiring color information by comparing light reception amounts of at least two specific wavelengths;
A reference color capture instruction receiving means for receiving a reference color capture instruction;
Reference color acquisition means for designating the color information acquired by the color information acquisition means in accordance with the reference color capture instruction as a reference color;
A degree of coincidence calculating means for comparing the color information sequentially obtained by the color information obtaining means with the reference color to obtain a degree of coincidence;
A photoelectric switch comprising: a detection signal output unit configured to perform workpiece determination by comparing the degree of coincidence with a predetermined determination threshold value and to output a detection signal based on the result of the workpiece determination. A main body having a light emitting diode for generating the detection light and a photodiode for generating the light reception signal;
A head unit that emits the detection light toward the detection region, and on which reflected light from the detection region is incident;
An optical fiber cable for transmitting the detection light and the reflected light between the main body and the head,
2. The photoelectric switch according to claim 1, wherein an end portion of the optical fiber that transmits the detection light and an end portion of the optical fiber that transmits the reflected light are disposed adjacent to each other in the head portion.   The photoelectric switch according to claim 2, further comprising an objective lens that is detachably attached to the head portion and condenses the detection light emitted from an end face of the optical fiber cable in the detection region.   The main body portion has a fiber connection portion to which the optical fiber cable is detachably connected, and an end portion of the optical fiber that transmits the detection light and an end portion of the optical fiber that transmits the reflected light are the fiber The photoelectric switch according to claim 2, wherein the photoelectric switch is arranged in parallel in the connection portion. Based on the light reception signal, provided with a light projection amount control means for controlling the light projection amount of the detection light,
5. The return light correction unit adjusts the return light amount according to the projected light amount, and corrects the received light signal based on the adjusted return light amount. 6. Photoelectric switch. Gain control means for controlling the gain of an amplifier that amplifies the light reception signal based on the light reception signal,
6. The return light correcting unit adjusts the return light amount according to the gain, and corrects the light reception signal based on the adjusted return light amount. Photoelectric switch.   The color information acquisition unit acquires color information including a ratio of a received light amount of each color component to a sum of a received light amount of a red component, a received light amount of a green component, and a received light amount of a blue component. The photoelectric switch according to any one of 6.   The photoelectric switch according to claim 1, wherein the return light correction unit corrects the light reception signal by subtracting the return light amount from a light reception amount for each specific wavelength. .   9. The photoelectric switch according to claim 1, further comprising a coincidence degree display means for displaying the coincidence degree.   The photoelectric switch according to claim 1, further comprising a determination threshold value input unit that receives an input of the determination threshold value.

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