JP2007033103A - Photoelectric sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photoelectric sensor capable of precisely detecting the glossiness of a target without using a beam splitter. <P>SOLUTION: The photoelectric sensor is equipped with one floodlight projecting region 11 for irradiating the target with light and three light detecting regions 14 for detecting the reflected light from the target. Three light detecting regions 14 are arranged on one straight line at an almost equal interval so as to be adjacent to the floodlight projecting region 11 so that the arranging direction of the central light detecting region 14 and the floodlight projecting region 11 crosses the arranging direction of three light detecting regions 14 at an almost right angle. The floodlight projecting region 11 and the central light detecting region 14 transmit only P polarized light and both left and right light detecting regions 14 transmit only S polarized light. The quantity of the diffused reflected light among light detection quantities is removed by subtracting the light detecting quantities in two left and right light detecting regions 14 from the light detecting quantity in the central light detecting region 14 to detect the quantity of regular reflected light and the glossiness of the target can be detected on the basis of the quantity of regular reflected light. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a photoelectric sensor, and more particularly to an improvement of a photoelectric sensor for detecting the glossiness of an object.

  A photoelectric sensor that is applied to a production line in a factory and detects the glossiness of an object based on the amount of received light by receiving reflected light of the irradiated light is known (for example, Patent Document 1). In this type of photoelectric sensor, for example, when light from a light emitting element passes through a polarizing filter, light having a predetermined polarization plane (for example, S-polarized light) is irradiated as irradiation light, and reflected light from an object is The light (for example, P-polarized light and S-polarized light) dispersed by the beam splitter is received by the light receiving element.

  When the irradiation light from the photoelectric sensor is reflected by the object, regular reflection light that is reflected at a reflection angle equal to the incident angle with respect to the object and diffusion that is reflected so as to be diffused at an arbitrary reflection angle different from the incident angle Reflected light is generated. When S-polarized light is irradiated as irradiation light, specular reflection light composed of S-polarization having the same polarization plane as the irradiation light and diffuse reflection light including both P-polarization and S-polarization are generated. The ratio of specular reflection light and diffuse reflection light generated from the irradiation light depends on the glossiness of the object. The higher the glossiness, the higher the proportion of specular reflection light, and the lower the glossiness, the lower the proportion of specular reflection light. Become. Therefore, the glossiness of the object can be detected based on the difference between the light amounts of the P-polarized light and the S-polarized light that are separated by the beam splitter and received by the light receiving element.

That is, in the above example, the S-polarized light received by the light receiving element is composed of regular reflection light and diffuse reflection light, whereas the P-polarized light received by the light receiving element is composed only of diffuse reflection light. Since the diffusely reflected light is generated by changing the polarization plane at random when the irradiated light is reflected by the object, the ratio of the P-polarized light and the S-polarized light in the diffusely reflected light is substantially the same. Therefore, the amount of specularly reflected light can be detected by subtracting the amount of P-polarized light from the amount of received S-polarized light, and the glossiness of the object is detected based on the detected amount of specularly reflected light. be able to.
Japanese Patent No. 3264143

  However, in the configuration in which the reflected light is dispersed using the beam splitter, there is a problem that it is difficult to reduce the size of the sensor body because a space for arranging the beam splitter must be provided in the sensor body. It was.

  In addition, when the reflection surface of the irradiated light on the object is inclined with respect to the surface substantially orthogonal to the irradiated light, the incident angle of the reflected light from the object incident on the beam splitter is shifted, and the incident light The spectral characteristics of the beam splitter with respect to the reflected light may change. In this case, the light incident on the beam splitter cannot be dispersed well, and light having a polarization plane different from the light that should pass through the beam splitter (for example, P-polarized light) passes through the beam splitter or the beam splitter. The light having a polarization plane different from the light to be reflected (for example, S-polarized light) may be reflected by the beam splitter, and the glossiness of the object may not be detected well. Therefore, conventionally, in order to allow only light having a predetermined polarization plane to enter the light receiving element, in addition to the beam splitter, a polarizing filter for passing light that has passed through the beam splitter and light reflected by the beam splitter, respectively. This was also a factor in increasing the size of the sensor body.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a photoelectric sensor that can accurately detect the glossiness of an object without using a beam splitter. Another object of the present invention is to further reduce the size of a photoelectric sensor for detecting the glossiness of an object.

  The photoelectric sensor according to the present invention is a photoelectric sensor for detecting the glossiness of an object. The photoelectric sensor irradiates the object with light, and is directly adjacent to the light projecting part at substantially equal intervals. Three light-receiving portions that are arranged on a line and receive reflected light from the object, respectively, and the direction in which the central light-receiving portion and the light-projecting portion among the three light-receiving portions are arranged, and the three light-receiving portions. The light projecting unit and the central light receiving unit include a first filter that allows light having a predetermined first polarization plane to pass through, and receive light other than the central light receiving unit. The unit includes a second filter that allows light having a second polarization plane different from the first polarization plane to pass therethrough.

  According to such a structure, light can be irradiated from a light projection part, and the reflected light in the target object of the irradiation light can be received by three light-receiving parts. Since the central light receiving unit includes a first filter that allows only light having the same first polarization plane as the light projecting unit to pass therethrough, specular reflection light on the object and diffuse reflection light having the first polarization plane are generated. The light is received by the central light receiving unit. On the other hand, since the other two light receiving parts are provided with a second filter that allows only light having a second polarization plane different from that of the light projecting part to pass therethrough, only diffuse reflection light having the second polarization plane can be used. Light is received by the two light receiving units.

  Since the diffuse reflection light is generated by randomly changing the polarization plane when the irradiation light is reflected by the object, the ratio of the diffuse reflection light having the first polarization plane and the diffuse reflection light having the second polarization plane is It is almost the same. Therefore, if a coefficient for matching the amount of diffuse reflected light received by the central light receiving unit with the sum of the amount of diffuse reflected light received by the other two light receiving units is set in advance, After performing gain adjustment based on the coefficient, the amount of diffusely reflected light in the received light amount is removed by subtracting the received light amount in the other two light receiving units from the received light amount in the central light receiving unit, and regular reflection The amount of light can be detected. Therefore, if the glossiness of the object is detected based on the detected amount of specularly reflected light, the glossiness of the object can be detected without using a beam splitter, and the photoelectric sensor can be further miniaturized.

  In addition, since the direction in which the center light receiving unit and the light projecting unit are arranged is substantially orthogonal to the direction in which the three light receiving units are arranged, even if the distance between the sensor main body and the object changes, The ratio of the amount of received light hardly changes. That is, the position where the light incident on the target object from the light projecting unit at a predetermined incident angle and reflected at the target object at the predetermined reflection angle reaches the sensor main body according to the change in the distance between the sensor main body and the target object. The light projecting unit and the light receiving unit will be displaced along the direction in which the light receiving unit and the light projecting unit are arranged in a direction that is substantially orthogonal to the direction in which the three light receiving units are arranged. Even when the distance between the sensor body and the object changes, the amount of light received at each light receiving portion changes at substantially the same rate, so the ratio of the amount of light received at each light receiving portion hardly changes. Therefore, even when the distance between the sensor main body and the object changes, the glossiness of the object can be accurately detected by performing gain adjustment based on the same preset coefficient.

  Furthermore, even when the angle of the reflection surface of the object changes due to the configuration in which the light having the second polarization plane is received by the two light receiving units disposed symmetrically with respect to the central light receiving unit, The sum of the amounts of light received by these two light receiving portions hardly changes. That is, when the angle of the reflection surface of the object changes, the distance between one of the two light receiving parts and the object becomes closer and the amount of received light increases, but the distance between the other light receiving part and the object increases. However, since the amount of light received decreases and the amount of received light decreases, the sum of the amounts of light received by the two light receiving portions hardly changes. Therefore, even when the angle of the reflecting surface of the object changes, the glossiness of the object can be detected with high accuracy by performing gain adjustment based on the same preset coefficient.

  The photoelectric sensor according to the present invention includes a light projecting / receiving surface through which the irradiation light from the light projecting unit and the reflected light from the object pass, and the light projecting / receiving surface through which the irradiation light from the light projecting unit passes. A light region and three light receiving regions through which reflected light from the object toward the three light receiving units respectively pass are formed, and the first filter is a light receiving region corresponding to the light projecting region and the central light receiving unit. The second filter is disposed in a light receiving region corresponding to a light receiving unit other than the central light receiving unit.

  According to such a configuration, it is possible to irradiate light from the light projecting unit through the light projecting region, and to receive the reflected light of the irradiated light on the object through the three light receiving regions. In this case, if the light projecting area and the central light receiving area are configured by one filter (first filter), the structure can be simplified and the manufacturing cost can be reduced.

  The photoelectric sensor according to the present invention includes three light receiving slits that allow at least a part of reflected light from the object to the three light receiving units to pass therethrough. According to such a configuration, the amount of light received by each light receiving unit can be limited to a necessary and sufficient fixed amount or less.

  In the photoelectric sensor according to the present invention, each of the three light receiving slits is formed in an elongated shape, and the longitudinal direction of each light receiving slit is arranged along the direction in which the corresponding light receiving unit and the light projecting unit are aligned. ing.

  According to such a configuration, even when the distance between the sensor main body and the target object changes, the position where the light reflected at the predetermined reflection angle at the target object reaches each light receiving unit is between the sensor main body and the target object. By merely shifting along the longitudinal direction of each light receiving slit according to the change in distance, it is possible to prevent variations in the amount of light passing through each light receiving slit due to the change in the distance between the sensor body and the object. Therefore, even when the distance between the sensor body and the object changes, the glossiness of the object can be detected with higher accuracy.

  In the photoelectric sensor according to the present invention, the three light receiving portions can receive the reflected light from the object only when the distance from the object is within a predetermined range, and the three light receiving slits are arranged in the short direction. The length is formed to be shorter than the diameter of the reflected light from the object in the state where the object is closest within the predetermined range.

  According to such a configuration, when the distance between the sensor main body and the object is close and the diameter of the reflected light from the object is large, only a part of the reflected light passes through the light receiving slit. The amount of received light in can be limited to a necessary and sufficient fixed amount or less.

  The photoelectric sensor according to the present invention is slidably arranged, and passes through the light projection slit by sliding the slit plate and a slit plate formed with a light projection slit that allows at least part of the irradiation light to pass therethrough. And an operation unit for adjusting the amount of irradiation light.

  According to such a configuration, the irradiation area of the irradiation light on the object is changed by sliding the slit plate and adjusting the amount of irradiation light passing through the light projection slit according to the size of the object. Can be made. Therefore, the glossiness can be detected with higher accuracy by the irradiation light according to the size of the object.

  A photoelectric sensor according to the present invention includes an optical fiber that supplies light to the light projecting unit, and the light receiving unit includes a photoelectric conversion element that outputs an electrical signal corresponding to the amount of light received from an object. Is done.

  According to such a configuration, the light emitted from the light projecting unit can be supplied from the outside of the sensor body to the light projecting unit via the optical fiber, and the light received by the light receiving unit can be converted into an electrical signal and output. it can. If light is supplied to the light projecting unit through an optical fiber that is not easily affected by disturbance, more uniform irradiation light can be obtained, and thus the glossiness can be detected with high accuracy. On the other hand, if the light received by the light receiving unit is output to the outside through an optical fiber, and the optical fiber is used for both the light projecting and light receiving paths, the attenuation of the light carried by the optical fiber increases. By adopting a configuration in which the light received by the light receiving unit is converted into an electric signal and output, it is possible to prevent a decrease in detection accuracy due to light attenuation.

  A mounting mechanism for a photoelectric sensor according to the present invention includes a support member that supports the photoelectric sensor, and a mounting member that is connected to the support member and mounts the photoelectric sensor at a predetermined position, and the mounting member is attached to the support member. Thus, the support member can be pivotably connected within a predetermined angle range (for example, 90 °), and the support member can be held at an arbitrary angle within the predetermined angle range.

  In addition, the photoelectric sensor mounting mechanism according to the present invention is applied to a photoelectric sensor that transports light through an optical fiber, the mounting mechanism is disposed facing a surface of the photoelectric sensor to which the optical fiber is mounted, and the support member. At least one of the attachment members is formed with a hole or a recess for allowing the optical fiber to pass therethrough.

  According to the present invention, the amount of specular reflected light can be detected by subtracting the amount of received light at the other two light receiving units from the amount of received light at the central light receiving unit. If the glossiness of the object is detected based on this, the glossiness of the object can be detected without using a beam splitter, and the photoelectric sensor can be further downsized. In addition, since the direction in which the center light receiving unit and the light projecting unit are arranged is substantially orthogonal to the direction in which the three light receiving units are arranged, even if the distance between the sensor main body and the object changes, The ratio of the amount of received light hardly changes, and the glossiness of the object can be detected with high accuracy. Furthermore, even when the angle of the reflection surface of the object changes due to the configuration in which the light having the second polarization plane is received by the two light receiving units disposed symmetrically with respect to the central light receiving unit, The sum of the amounts of light received by these two light receiving portions hardly changes, and the glossiness of the object can be detected with high accuracy.

  According to the present invention, the amount of light received by the three light receiving portions can be limited to a necessary and sufficient fixed amount or less by the light receiving slit. If the longitudinal direction of each light receiving slit is arranged along the direction in which the corresponding light receiving part and light projecting part are aligned, the variation in the amount of light passing through each light receiving slit due to the change in the distance between the sensor body and the object Therefore, the glossiness of the object can be detected with higher accuracy.

  According to the present invention, the irradiation area of the irradiation light on the object is changed by sliding the slit plate and adjusting the amount of irradiation light passing through the light projection slit according to the size of the object. Therefore, the glossiness can be detected with higher accuracy with the irradiation light according to the size of the object.

  According to the present invention, more uniform irradiation light can be obtained by supplying light to the light projecting unit via an optical fiber that is not easily affected by disturbances, so that the glossiness can be detected more accurately. In addition, by converting the light received by the light receiving unit into an electrical signal and outputting it, it is possible to prevent a decrease in detection accuracy due to light attenuation.

  FIG. 1 is a conceptual diagram showing a configuration example of a photoelectric sensor 1 according to an embodiment of the present invention. As shown in FIG. 1, the photoelectric sensor 1 irradiates light on the object 4 and receives a reflected light from the object 4, and a controller 3 connected to the sensor body 2. It has. This photoelectric sensor 1 is applied to a production line of a factory, etc., and irradiates light on an article (object 4) conveyed on the production line, so that the object 4 is based on the amount of received reflected light. Can be detected. Thereby, for example, it is possible to determine whether or not the article is covered with a film-like protective sheet having high glossiness.

  The sensor body 2 includes one light projecting unit 5 for irradiating light toward the object 4 and three light receiving units 6 for receiving reflected light from the object 4. The sensor body 2 is formed with a light projecting / receiving surface 7 through which irradiation light from the light projecting unit 5 and reflected light from the object 4 pass. Light is supplied to the light projecting unit 5 from the controller 3 through the optical fiber 8, and the light from the optical fiber 8 is formed on the light projecting / receiving surface 7 through the light projecting slit 9 and the light projecting lens 10. The target 4 is projected through the projected region 11. The light projecting area 11 includes a first filter 12 that allows only light having a predetermined polarization plane to pass. In this example, only so-called P-polarized light passes through the light projecting area 11 and is projected onto the object 4. It has come to be.

  When the irradiation light from the sensor body 2 is reflected by the reflection surface 4A of the object 4, the regular reflection light reflected at a reflection angle equal to the incident angle with respect to the reflection surface 4A and an arbitrary reflection angle different from the incident angle. Diffuse reflected light is reflected so as to diffuse. The regular reflection light consists only of P-polarized light having the same polarization plane as the irradiation light. On the other hand, the diffusely reflected light is generated by randomly changing the polarization plane when the irradiated light is reflected by the object 4, so that not only the P-polarized light but also the S-polarized light whose polarization plane is inclined by 90 ° with respect to the P-polarized light. Are included at approximately the same rate. The ratio between the specular reflection light and the diffuse reflection light generated from the irradiation light depends on the glossiness of the object 4. The higher the glossiness, the higher the ratio of the specular reflection light, and the lower the glossiness, the higher the ratio of the specular reflection light. Lower.

  Each light receiving unit 6 is provided with a light receiving element (photoelectric conversion element) 13 constituted by, for example, a photodiode. On the light projecting / receiving surface 7, light receiving areas 14 respectively facing the three light receiving elements 13 are formed, and reflected light from the object 4 enters these light receiving areas 14. One of the three light receiving regions 14 is configured by the first filter 12 that passes only P-polarized light having the same polarization plane as the irradiation light, and the other two light receiving regions 14 are different from the irradiation light. The second filter 15 transmits only light having a polarization plane (for example, S-polarized light).

  The P-polarized light incident from the light receiving region 14 constituted by the first filter 12 is received by the light receiving element 13 connected to the P polarized light receiving circuit 18 through the light receiving lens 16 and the light receiving slit 17. S-polarized light incident from the light receiving region 14 constituted by the second filter 15 is received by the light receiving element 13 connected to the S polarized light receiving circuit 19 through the light receiving lens 16 and the light receiving slit 17. The P-polarized light receiving circuit 18 and the two S-polarized light receiving circuits 19 are formed on the mounting surface of the common circuit board 20, and the three light receiving elements 13 are mounted on the circuit board 20.

  The controller 3 includes a control unit 21 including a CPU, a light emitting circuit 22 electrically connected to the control unit 21, and a light emitting element 23 mounted on the light emitting circuit 22. The light emitting element 23 is configured by, for example, a light emitting diode (LED), and light emitted from the light emitting element 23 is supplied to the light projecting unit 5 of the sensor main body 2 through the optical fiber 8. The control unit 21 is electrically connected to the P-polarized light receiving circuit 18 and the two S-polarized light receiving circuits 19 via the electric wiring 24. The control unit 21 can control the amount of light emitted from the light emitting element 23 by controlling the voltage supplied to the light emitting circuit 22, and the P-polarized light receiving circuit 18 and S according to the amount of light received by each light receiving element 13. The glossiness of the object 4 can be detected by performing a predetermined calculation based on the electrical signal output from the polarized light receiving circuit 19.

  FIG. 2 is a perspective view of the sensor body 2 of FIG. FIG. 3 is a longitudinal sectional view of the sensor main body 2 of FIG. In the following, for convenience, the right side in FIG. 3 will be described as the front, the left side as the rear, the upper side as the upper side, and the lower side as the lower side.

  The sensor body 2 has an outer shape defined by a resin casing 30 formed in a substantially hollow rectangular parallelepiped shape. The light projecting unit 5 and the light receiving unit 6 are accommodated in the casing 30. Through holes 31 penetrating the casing 30 in the left-right direction are formed in the upper and lower ends of the rear surface of the casing 30, and a fixing tool such as a bolt is passed through these through holes 31 to an attachment mechanism 70 described later. The sensor body 2 can be installed at a desired position by fixing the casing 30 and attaching the attachment mechanism 70 to a predetermined attachment position.

  The tip of the optical fiber 8 is fixed in a straight line in the casing 30 so as to incline downward as it goes forward. The light projecting unit 5 is disposed in the upper portion of the casing 30 and irradiates light obliquely downward toward the front along the direction in which the tip of the optical fiber 8 extends. On the other hand, the light receiving unit 6 is disposed at a lower portion in the casing 30 and receives light incident obliquely downward toward the rear. That is, the optical axis L1 of the light emitted from the light projecting unit 5 and the optical axis L2 of the light received by the light receiving unit 6 intersect each other. A substantially rectangular opening 32 is formed in the front surface of the casing 30, and a transparent plate 33 made of glass or plastic is fitted into the opening 32. Irradiation light from the light projecting unit 5 travels forward through the upper part of the transparent plate 33, and reflected light traveling rearward from the object 4 enters the casing 30 through the lower part of the transparent plate 33.

  The light projecting lens 10, the light receiving lens 16, the light receiving element 13, and the circuit board 20 are integrally held by a holding member 34. FIG. 4 is a perspective view of the holding member 34 of FIG. As shown in FIGS. 3 and 4, the light projecting lens 10 includes a substantially rectangular plate-shaped portion 10 </ b> A, an incident surface 10 </ b> B formed so as to be convexly curved backward from the rear surface of the plate-shaped portion 10 </ b> A, It is configured by integrally forming an exit surface 10C formed so as to be convexly curved with a smaller curvature than the entrance surface 10B from the front surface of the shaped portion 10A toward the front. The light projecting lens 10 is arranged such that a straight line connecting the apex of the incident surface 10B and the apex of the output surface 10C is along the optical axis L1 of the light from the optical fiber 8.

  The holding member 34 is formed in a substantially U-shape when viewed from the front by forming a substantially rectangular recess 35 that is recessed downward on the upper surface of the substantially rectangular resin material when viewed from the front (see FIG. 4). That is, the holding member 34 is configured by integrally forming a lower holding portion 36 extending in the left-right direction and side plate portions 37 extending upward from both left and right end portions of the lower holding portion 36. The opposing surfaces of the side plate portions 37 are each formed with a receiving groove 38 that extends in a straight line and is inclined so that the upper end portion is positioned forward of the lower end portion with respect to the vertical direction. The light projecting lens 10 is press-fitted from above so that the left and right side edges of the plate-like portion 10A are housed in the housing groove 38, so that the lower edge of the plate-like portion 10A is placed on the upper surface of the lower holding portion 36. It arrange | positions in the recessed part 35 in the state contact | abutted.

  A slit plate 40 in which a light projection slit 9 is formed is disposed behind the light projection lens 10 so as to be substantially orthogonal to the optical axis L1 (see FIG. 3). The light projecting slit 9 is configured by forming a substantially circular through hole at a position where the optical axis L1 passes through the slit plate 40. At least a part of the light emitted from the optical fiber 8 enters the incident surface 10B of the projection lens 10 through the projection slit 9, and is projected as parallel light from the exit surface 10C of the projection lens 10. The The slit plate 40 is attached to the casing 30 so as to be slidable in the left-right direction. The upper end portion of the slit plate 40 projects outward through an opening 41 formed on the upper surface of the casing 30, and the projecting portion constitutes an operation unit 42 for sliding the slit plate 40 in the left-right direction. is doing.

  On the front surface of the lower holding portion 36 of the holding member 34, three concave portions 43 having a substantially rectangular shape in front view that are recessed rearward are formed side by side in the left-right direction, and the light receiving lens 16 is accommodated in each internal space. Yes. The three recesses 43 are arranged on a straight line at substantially equal intervals in the left-right direction. On the other hand, on the rear surface of the lower holding portion 36 of the holding member 34, three concave portions 44 having a substantially rectangular shape in rear view that are recessed forward are arranged in the left-right direction. These recesses 44 are opposed to the rear of each recess 43 in which the light receiving lens 16 is accommodated with a partition wall 45 therebetween, and the light receiving element 13 is accommodated in each internal space.

  Each light receiving lens 16 is integrally formed with a substantially rectangular plate-like portion 16A constituting an incident surface 16B having a flat front surface and an exit surface 16C formed so as to be convexly curved rearward from the rear surface of the plate-like portion 16A. It is comprised by forming. Each light receiving lens 16 is housed in a state where the peripheral edge of the plate-like portion 16 </ b> A is in contact with the inner surface of the concave portion 43 by being press-fitted into the concave portion 43 of the holding member 34. Each light receiving lens 16 is arranged such that the incident surface 16B is orthogonal to the optical axis L2 of the reflected light from the object 4, and the vertex of the output surface 16C passes through the optical axis L2. Reflected light from the object 4 that has entered the casing 30 is collected by passing through the light receiving lens 16, and at least part of the light is received by the light receiving element 13 through the light receiving slit 17 formed in the partition wall 45. Is done.

  FIG. 5 is a front view of the sensor body 2 of FIG. On the rear surface of the transparent plate 33, there are one first polarizing film 51 that integrally constitutes the two first filters 12, and two second polarizing films 52 that respectively constitute the two second filters 15. The light projecting / receiving surface 7 is composed of the entire front surface of each of the polarizing films 51 and 52. A region facing the light projecting lens 10 on the front surface of the first polarizing film 51 constitutes a light projecting region 11, and a region facing the central light receiving lens 16 constitutes a central light receiving region 14. The front surface of each second polarizing film 52 constitutes a light receiving region 14 that faces the light receiving lenses 16 on both the left and right sides. By constructing the light projecting region 11 and the central light receiving region 14 with a single polarizing film 51, the structure can be simplified and the manufacturing cost can be reduced.

  Each of the polarizing films 51 and 52 is made of one substantially rectangular film member that can pass only light having a predetermined polarization plane. That is, the film member is composed of a substantially T-shaped portion (first polarizing film 51) that integrally configures the light projecting region 11 and the central light receiving region 14, and the two approximately constituting the left and right light receiving regions 14. In a state where the first polarizing film 51 is aligned with the polarization plane of the P-polarized light and the second polarizing film 52 is rotated by 90 ° with respect to the first polarizing film 51. Each is pasted on the rear surface of the transparent plate 33. Thereby, only the P polarized light can be passed through the first polarizing film 51 and only the S polarized light can be passed through the second polarizing film 52.

  The three light receiving areas 14 are arranged on a straight line at almost equal intervals adjacent to the lower side of the light projecting area 11. More specifically, the direction in which the central light receiving region 14 and the light projecting region 11 are arranged, that is, the optical axis L1 of the light emitted from the light projecting region 11 and the optical axis of the light received by the central light receiving region 14. The direction connecting L2 (up and down direction) and the direction in which the three light receiving regions 14 are arranged, that is, the direction connecting the optical axes L2 of the light received by the three light receiving regions 14 (right and left directions) are almost orthogonal to each other. Yes.

  In the present embodiment, light is irradiated through the light projecting area 11 of the light projecting / receiving surface 7 formed on the sensor main body 2, and the reflected light of the irradiated light on the object 4 is transmitted from the three light receiving areas 14 to the sensor main body 2. Can be made incident. Since the central light receiving region 14 passes only P-polarized light having the same polarization plane as that of the light projecting region 11, specularly reflected light from the object 4 and diffusely reflected light composed of P-polarized light are transmitted from the central light receiving region 14. The light enters the sensor body 2. On the other hand, the other two left and right light receiving regions 14 pass only S-polarized light having a polarization plane different from that of the light projecting region 11, so that only diffusely reflected light composed of S-polarized light is detected from these two light receiving regions 14. Incident on the main body 2.

  As described above, the diffusely reflected light is generated by randomly changing the polarization plane when the irradiated light is reflected by the object 4, so the ratio of the diffusely reflected light composed of P-polarized light and the diffusely reflected light composed of S-polarized light is It is almost the same. Therefore, a coefficient for matching the light amount of the diffuse reflected light passing through the central light receiving region 14 with the sum of the light amounts of the diffuse reflected light passing through the other two light receiving regions 14 is set in advance. If stored in a memory (not shown), the control unit 21 adjusts the gain based on the coefficient, and then calculates the received light amount in the other two light receiving regions 14 from the received light amount in the central light receiving region 14. By subtracting, the amount of diffusely reflected light in the amount of received light can be removed, and the amount of specularly reflected light can be detected. Therefore, if the glossiness of the object 4 is detected based on the detected amount of specularly reflected light, the glossiness of the object 4 can be detected without using a beam splitter, and the photoelectric sensor 1 can be further downsized.

  Further, since the direction in which the central light receiving region 14 and the light projecting region 11 are arranged and the direction in which the three light receiving regions 14 are arranged are substantially orthogonal, even when the distance between the sensor body 2 and the object 4 changes. The ratio of the amount of light received in each light receiving region 14 hardly changes. FIG. 6 is a schematic diagram illustrating an example of a change in the optical path according to the distance between the sensor body 2 and the object 4. As shown in FIG. 6, the light incident on the reflecting surface 4 </ b> A of the object 4 from the light projecting region 11 at a predetermined incident angle θ <b> 1 and reflected by the reflecting surface 4 </ b> A at the predetermined reflecting angle θ <b> 2 The position reaching 7 is shifted along the direction (vertical direction) in which the light projecting region 11 and the light receiving region 14 are arranged in accordance with the change in the distance between the sensor body 2 and the object 4.

  That is, as shown by the solid line in FIG. 6, when the distance between the sensor body 2 and the object 4 is short, the reflected light from the object 4 reaches the upper side of the light projecting / receiving surface 7, whereas FIG. As indicated by a broken line in FIG. 6, when the distance between the sensor body 2 and the object 4 is long, the reflected light from the object 4 reaches the lower side of the light projecting / receiving surface 7. If the direction in which the center light receiving region 14 and the light projecting region 11 are arranged and the direction in which the three light receiving regions 14 are arranged are almost orthogonal, even if the distance between the sensor body 2 and the object 4 changes, Since the amount of light received in the light receiving region 14 changes at substantially the same rate, the ratio of the amount of light received in each light receiving region 14 hardly changes. Therefore, even when the distance between the sensor main body 2 and the object 4 changes, the glossiness of the object can be accurately detected by performing gain adjustment based on the same preset coefficient.

  FIG. 7 is a front view of the holding member 34 of FIG. In FIG. 7, the light projecting lens 10, the light receiving lens 16, the light receiving element 13, and the circuit board 20 are omitted. Each light receiving slit 17 is formed in a substantially rectangular shape with respect to the partition wall 45. The central light receiving slit 17 is arranged such that its longitudinal direction extends in the vertical direction. On the other hand, the left and right light receiving slits 17 are arranged in an inclined state so that the upper end portion is positioned inside the lower end portion with respect to the vertical direction.

  More specifically, the longitudinal direction of each light receiving slit 17 is the direction in which the corresponding light receiving region 14 and the light projecting region 11 are arranged, that is, the optical axis L2 of the light received by the corresponding light receiving region 14, and the light projecting region. It arrange | positions so that the direction which connects the optical axis L1 of the light irradiated from the optical area | region 11 may be followed. In FIG. 7, the optical axis L2 of the light received by the light receiving areas 14 on both the left and right sides is not located in the corresponding light receiving slits 17, but this corresponds to the positions of the light projecting area 11 and the light receiving areas 14 on both the left and right sides. This is because light is incident on the light receiving regions 14 while being inclined in the left and right directions based on the fact that they are displaced in the left and right directions. Although not shown in FIG. When viewed along the optical axis L2 of light, each optical axis L2 passes through the corresponding light receiving slit 17.

  FIG. 8 is a schematic diagram illustrating an example of a change in the amount of light passing through the light receiving slit 17 according to the distance between the sensor body 2 and the target object 4, and (a) illustrates the relationship between the sensor body 2 and the target object 4. When the distance is relatively long, (b) indicates that the distance between the sensor body 2 and the object 4 is shorter than (a), and (c) indicates that the sensor body 2 and the object 4 are further The case where the distance of is near is shown. When the distance between the sensor body 2 and the object 4 is relatively long, as shown in FIG. 8A, the reflected light from the object 4 has a small irradiation area, and all of the reflected light passes through the light receiving slit 17. pass.

  When the distance between the sensor main body 2 and the object 4 is shorter than in the case of FIG. 8A, the reflected light from the object 4 is along the longitudinal direction of the light receiving slit 17 as shown in FIG. 8B. Transitions downward and the irradiation area increases. At this time, the ratio that the reflected light spreads in the short direction is larger than the ratio that spreads in the longitudinal direction of the light receiving slit 17, and the light at both ends along the short direction of the light receiving slit 17 passes through the light receiving slit 17. Blocked.

  When the distance between the sensor body 2 and the object 4 is further reduced than in the case of FIG. 8B, the reflected light from the object 4 is transmitted in the longitudinal direction of the light receiving slit 17 as shown in FIG. Further, the irradiation area further increases, and light at both ends along the short side of the light receiving slit 17 and light at the lower end along the longitudinal direction are blocked from passing through the light receiving slit 17. In this way, by providing the light receiving slits 17 in association with the respective light receiving regions 14, when the distance between the sensor body 2 and the object 4 is short and the diameter of the reflected light from the object 4 is large, the reflected light Since only a part of the light passes through the light receiving slit 17, the amount of light received by each light receiving unit 6 can be limited to a necessary and sufficient fixed amount or less.

  In the present embodiment, as shown in FIG. 7, since the longitudinal direction of each light receiving slit 17 is arranged along the direction in which the corresponding light receiving region 14 and the light projecting region 11 are arranged, the sensor body 2 The change in the amount of light passing through each light receiving slit 17 in accordance with the change in the distance between the object 4 and the object 4 is as shown in FIG. Therefore, even when the distance between the sensor body 2 and the object 4 changes, the position at which the light reflected by the object 4 at a predetermined reflection angle reaches each light receiving region 14 is between the sensor body 2 and the object 4. By merely shifting along the longitudinal direction of each light receiving slit 17 according to the change in distance, it is possible to prevent variation in the amount of light passing through each light receiving slit 17 due to the change in the distance between the sensor body 2 and the object 4. Therefore, even when the distance between the sensor body 2 and the object 4 changes, the glossiness of the object 4 can be detected with higher accuracy.

  In addition, since the S-polarized light included in the reflected light from the object 4 passes through the two light receiving regions 14 arranged symmetrically with respect to the central light receiving region 14, the angle of the reflecting surface 4A of the object 4 is Even if it changes, the sum of the received light amounts in these two light receiving regions 14 is unlikely to change. That is, when the angle of the reflecting surface 4A in the object 4 changes, the distance between one of the two light receiving areas 14 and the object 4 becomes shorter, and for example, as shown in FIG. The amount of light increases, but the distance between the other light receiving region 14 and the object 4 increases accordingly, and the amount of received light decreases, for example, as shown in FIG. The sum of is difficult to change. Therefore, even when the angle of the reflecting surface 4A in the object 4 changes, the glossiness of the object can be detected with high accuracy by performing gain adjustment based on the same preset coefficient.

  FIG. 9 is a perspective view showing an attachment mode of the slit plate 40 of FIG. A positioning member 60 for positioning the distal end portion at a predetermined position in the casing 30 is attached to the distal end portion of the optical fiber 8. The slit plate 40 is attached to the positioning member 60 so as to be slidable in the left-right direction.

  The tip of the optical fiber 8 is attached to the rear surface of the positioning member 60. A recess 61 that is recessed rearward is formed on the front surface of the positioning member 60, and a guide member 62 that extends in the left-right direction is disposed at a predetermined interval forward from the bottom surface of the recess 61. . Both left and right ends of the guide member 62 are coupled to the front surface of the positioning member 60.

  The slit plate 40 includes a main body portion 63 disposed along the front surface of the positioning member 60, an engagement portion 64 having a substantially U-shaped cross section coupled to the upper end portion of the main body portion 63, and an upper end portion of the engagement portion 64. And a connecting portion 65 that connects the operating portion 42 and the operating portion 42 are integrally formed. The light projection slit 9 is formed so as to penetrate the main body 63 in the front-rear direction. The engaging portion 64 is disposed in a space between the concave portion 61 of the positioning member 60 and the guide member 62 and engages with the guide member 62 so as to be slidable in the left-right direction.

  The operation portion 42 is integrally formed with a main body portion 66 having a substantially rectangular shape in plan view extending in the left-right direction and a protrusion 67 formed so as to extend in the front-rear direction at the center portion in the left-right direction of the main body portion 66. It is constituted by. The connecting portion 65 of the slit plate 40 is connected to the central portion in the left-right direction of the main body portion 66 of the operation portion 42. Therefore, the slit plate 40 can be slid in the left-right direction by operating the left-right direction by placing a finger on the operation unit 42 from above. The protrusion 67 of the operation unit 42 functions as a slip stopper when operating the operation unit 42 in the left-right direction.

  A through hole (not shown) for passing light from the optical fiber 8 is formed in the positioning member 60 so as to penetrate the positioning member 60 in the front-rear direction, and a slit plate is disposed in front of the through hole. The light projection slits 9 formed in the 40 main body parts 63 are opposed to each other. When the slit plate 40 is slid in the left-right direction, the area in which the through hole and the light projecting slit 9 overlap in the front-rear direction is changed, thereby changing the amount of irradiation light passing through the light projecting slit 9. According to such a configuration, the slit plate 40 is slid to adjust the amount of irradiation light that passes through the light projection slit 9 according to the size of the object 4, so that the irradiation light of the object 4 can be adjusted. The irradiation area can be changed. Therefore, the glossiness can be detected with higher accuracy by the irradiation light corresponding to the size of the object 4.

  In the present embodiment, the light emitted from the light projecting unit 5 is supplied from the outside of the sensor body 2 to the light projecting unit 5 through the optical fiber 8, and the light received by the light receiving unit 6 is electrically received by the light receiving element 13. It can be converted into a signal and output. If light is supplied to the light projecting unit 5 through the optical fiber 8 which is less susceptible to disturbance compared to an LED or the like, more uniform irradiation light can be obtained, so that the glossiness can be detected with high accuracy. . On the other hand, if the light received by the light receiving unit 6 is configured to be output to the outside through an optical fiber, and the optical fiber is used for both the light projecting and light receiving paths, the attenuation of the light carried by the optical fiber increases. Therefore, the configuration in which the light received by the light receiving unit 6 is converted into an electrical signal and output as in the present embodiment can prevent a decrease in detection accuracy due to light attenuation.

  FIG. 10 is an exploded perspective view showing one configuration example of the attachment mechanism 70 of the sensor body 2. FIG. 11 is a rear view showing a state in which the attachment mechanism 70 of FIG. 10 is attached to the sensor main body 2. The attachment mechanism 70 includes a support member 71 that supports the sensor body 2 and an attachment member 72 that is connected to the support member 71 and attaches the sensor body 2 to a predetermined position.

  The support member 71 is bent by a single metal plate and extends forward from the main plate portion 73 facing the back surface of the sensor main body 2 and the upper end portion and the lower end portion at one end edge in the left-right direction of the main plate portion 73. , And two fixing plate portions 74 for fixing the support member 71 to the sensor main body 2. Each fixed plate portion 74 is formed with a long hole 75 extending in the front-rear direction, and the through-hole 31 (see FIG. 2) of the sensor main body 2 is connected to the through-hole 31 (see FIG. 2) of the sensor body 2 from the left and right end surfaces. The sensor main body 2 can be fixed to the support member 71 by passing through a fixture 76 such as a bolt and connecting to a connecting plate 77 disposed on the other end surface side of the sensor main body 2 in the left-right direction.

  The mounting member 72 is bent by a single metal plate, extends to the rear from the main plate portion 78 that contacts the main plate portion 73 of the support member 71, and the lower end edge of the main plate portion 78, and moves the mounting member 72 to a predetermined position. And a mounting plate portion 79 for mounting. A long hole 80 extending in the left-right direction and a long hole 81 extending in the front-rear direction are formed in the mounting plate portion 79, and each of the long holes 80, 81 is fixed through a fixture (not shown). Thus, the sensor body 2 can be fixed while adjusting the position in the front-rear and left-right directions.

  An insertion hole 82 is formed in the main plate portion 78 of the mounting member 72 at a position facing the center position of the back surface of the sensor body 2, and a shaft member 83 such as a bolt is passed through the insertion hole 82, and the support member 71. The attachment member 72 and the support member 71 are connected by being fixed to the screw hole 84 formed in the main plate portion 73. At this time, the shaft member 83 is fixed to the screw hole 84 with such a tightening force that the mounting member 72 can rotate around the shaft member 83 with respect to the support member 71 and can be held at an arbitrary angle. Is done.

  An arcuate guide hole 85 is formed in the main plate portion 78 of the mounting member 72 in an angular range of about 90 ° in the circumferential direction around the insertion hole 82. A guide member 86 such as a bolt is passed through the guide hole 85 and is fixed to a screw hole 87 formed in the main plate portion 73 of the support member 71, so that the guide member 86 can slide along the guide hole 85. . Thereby, the attachment member 72 and the support member 71 are between the state in which the guide member 86 is in contact with one end of the guide hole 85 and the state in which the other end of the guide hole 85 is in contact with the shaft member 83 as the center. Are connected to each other so as to be rotatable.

  FIG. 12 is a rear view showing an aspect when the support member 71 is rotated with respect to the mounting member 72, and (a) is a state in which the guide member 86 is in contact with one end (lower end) of the guide hole 85, (B) shows a state in which the guide member 86 is in contact with the other end (upper end) of the guide hole 85.

  As shown in FIG. 11, when the sensor body 2 is rotated counterclockwise in the drawing from the state where the guide member 86 is in the center of the guide hole 85, the guide member 86 slides downward along the guide hole 85. Then, the guide member 86 comes into contact with the lower end of the guide hole 85 when rotated by about 45 ° (see FIG. 12A). On the other hand, when the sensor body 2 is rotated clockwise in the drawing from the state shown in FIG. 11, the guide member 86 slides upward along the guide hole 85 and the guide member 86 is guided by about 45 °. It contacts the upper end of the hole 85 (see FIG. 12B). Therefore, the sensor main body 2 is attached by the attachment mechanism 70 so as to be rotatable within an angle range of about 90 °.

  The protective sheet placed on the article whose gloss level can be detected by the photoelectric sensor 1 is usually a so-called stretched film, and has a characteristic that the refractive index of light partially varies depending on the stretching direction at the time of film formation. have. Such a refractive index characteristic has a peak every 90 ° when the protective sheet is rotated in its plane.

  In the present embodiment, by rotating the support member 71 with respect to the mounting member 72 in a state where the sensor main body 2 is mounted at a predetermined mounting position by the mounting mechanism 70, the sensor body 2 is rotated at an angle range of about 90 °. Can be held at any angle within. Therefore, by adjusting the angle of the sensor body 2 in accordance with the refractive index characteristic according to the stretch direction of the stretched film, the regular reflection light of the light emitted from the light projecting area 11 of the sensor body 2 is received at the center light receiving area 14. Can be finely adjusted to be incident on the light. In particular, since the sensor body 2 can be rotated within an angle range of about 90 ° where a peak of characteristics corresponding to the stretch direction of the stretched film appears, it is possible to detect glossiness satisfactorily according to the characteristics of the object. .

  Although not shown in FIGS. 10-12, since the optical fiber 8 (refer FIG. 3) is attached to the back surface of the sensor main body 2, it opposes the back surface of the sensor main body 2 like this Embodiment. In the configuration in which the attachment mechanism 70 is arranged, it is necessary to devise the routing of the optical fiber 8. That is, when the optical fiber 8 comes into contact with the attachment mechanism 70 and is bent or bent, the light transported by the optical fiber 8 is attenuated, so that the optical fiber 8 comes into contact with the attachment mechanism 70 and is bent or bent. A configuration that can prevent this is preferable.

  Therefore, in the present embodiment, the main plate portion 73 of the support member 71 is formed with a recess 88 at a position facing the mounting position of the optical fiber 8 on the back surface of the sensor body 2, and the main plate portion 78 of the mounting member 72. In this case, a recess 89 is formed over the entire range where the recess 88 of the support member 71 faces when the support member 71 rotates within an angle range of about 90 ° about the shaft member 83. Accordingly, the guide member 86 is not only in the center portion of the guide hole 85 as shown in FIG. 11 but also in the state where the guide member 86 is in contact with the lower end of the guide hole 85 as shown in FIG. And in any state where the guide member 86 is in contact with the upper end of the guide hole 85 as shown in FIG. 12B, the recess 88 of the support member 71 and the recess 89 of the mounting member 72 are opposed to each other. The optical fiber 8 can be passed through these recesses 88 and 89 without being bent or bent.

  However, in the present embodiment, the configuration in which the support member 71 and the mounting member 72 can rotate within an angle range of about 90 ° has been described, but the angle range in which the support member 71 and the attachment member 72 can rotate is not limited to about 90 °. For example, it may be about 180 °. Further, the mounting mechanism 70 is not limited to the photoelectric sensor 1 having the configuration as in the present embodiment, but is configured to separate the reflected light from the object using another type of photoelectric sensor, for example, a beam splitter. It is applicable also to the photoelectric sensor which has this.

  In the present embodiment, the configuration in which the P-polarized light is emitted from the light projecting unit 5 has been described. However, the configuration is not limited to this configuration, and for example, a configuration in which the S-polarized light is irradiated may be used. In this case, a configuration in which the central light receiving region 14 of the three light receiving regions 14 transmits S-polarized light and the left and right light receiving regions 14 transmit P-polarized light may be employed.

  In addition, the light projecting area 11 and the light receiving area 14 are not limited to the configuration formed on the same light projecting / receiving surface 7, but are formed on the light projecting surface and the light receiving surface having the same or different distance from the object. Such a configuration may be adopted.

  The present invention is not limited to the contents of the above-described embodiment, and various modifications can be made within the scope of the claims.

It is a conceptual diagram which shows the example of 1 structure of the photoelectric sensor by embodiment of this invention. It is a perspective view of the sensor main body of FIG. It is a longitudinal cross-sectional view of the sensor main body of FIG. It is a perspective view of the holding member of FIG. It is a front view of the sensor main body of FIG. It is the schematic which shows an example of the change of the optical path according to the distance of a sensor main body and a target object. It is a front view of the holding member of FIG. It is the schematic which shows an example of the change of the light quantity which passes a light-receiving slit according to the distance of a sensor main body and a target object, Comprising: (a) is a case where the distance between a sensor main body and a target object is comparatively far (b ) Shows the case where the distance between the sensor body and the object is shorter than that in (a), and (c) shows the case where the distance between the sensor body and the object is further closer than in (b). It is a perspective view which shows the attachment aspect of the slit board of FIG. It is a disassembled perspective view which shows one structural example of the attachment mechanism of a sensor main body. It is a rear view which shows the state in which the attachment mechanism of FIG. 10 was attached to the sensor main body. It is a rear view which shows the aspect at the time of rotating a supporting member with respect to an attachment member, (a) is the state which the guide member contact | abutted to the end (lower end) of a guide hole, (b) is a guide member The state which contact | abutted at the other end (upper end) of the guide hole is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Photoelectric sensor 2 Sensor main body 3 Controller 4 Object 5 Light projection part 6 Light reception part 7 Light projection / reception surface 8 Optical fiber 9 Light projection slit 11 Light projection area | region 12 1st filter 13 Light reception element 14 Light reception area 15 2nd filter 17 Light reception slit 40 Slit Plate 42 Operation Unit 51 First Polarizing Film 52 Second Polarizing Film 70 Mounting Mechanism 71 Support Member 72 Mounting Member

Claims (7)

In a photoelectric sensor for detecting the glossiness of an object,
One light projecting unit for irradiating the object with light;
Three light receiving parts that are arranged on a straight line at substantially equal intervals adjacent to the light projecting part and receive reflected light from the object, respectively.
The direction in which the center light receiving part and the light projecting part of the three light receiving parts are arranged is substantially perpendicular to the direction in which the three light receiving parts are arranged,
The light projecting unit and the central light receiving unit include a first filter that transmits light having a predetermined first polarization plane,
The photoelectric sensor, wherein a light receiving unit other than the central light receiving unit includes a second filter that transmits light having a second polarization plane different from the first polarization plane. Comprising a light projecting / receiving surface through which the irradiation light from the light projecting unit and the reflected light from the object pass,
On the light projecting / receiving surface, there are formed a light projecting region through which irradiation light from the light projecting unit passes and three light receiving regions through which reflected light directed from the object toward the three light receiving units respectively pass.
The first filter is disposed in a light receiving region corresponding to the light projecting region and the central light receiving unit,
The photoelectric sensor according to claim 1, wherein the second filter is arranged in a light receiving region corresponding to a light receiving unit other than the central light receiving unit.   3. The photoelectric sensor according to claim 1, further comprising: three light receiving slits that allow at least a part of reflected light from the object to travel toward the three light receiving units.   Each of the three light receiving slits is formed in an elongated shape, and the longitudinal direction of each light receiving slit is arranged so as to be along the direction in which the corresponding light receiving unit and the light projecting unit are aligned. The photoelectric sensor according to claim 3. The three light receiving parts can receive reflected light from the object only when the distance from the object is within a predetermined range,
5. The length of the three light receiving slits in the short direction is shorter than the diameter of the reflected light from the object in the state where the object is closest to within the predetermined range. The photoelectric sensor described in 1. A slit plate that is slidably arranged and formed with a light projection slit that allows at least part of the irradiation light to pass through;
6. The photoelectric sensor according to claim 1, further comprising an operation unit configured to adjust a light amount of the irradiation light passing through the light projection slit by sliding the slit plate. . An optical fiber for supplying light to the light projecting unit;
The photoelectric sensor according to claim 1, wherein the light receiving unit includes a photoelectric conversion element that outputs an electrical signal corresponding to a received light amount of reflected light from an object.

Images