JP2018066573A - Gap sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect a gap amount of a measurement target without being affected by interference of light.SOLUTION: A gap sensor includes: a light projector for radiating light to a gap of a measurement target 100; a lens 2; an optical receiver 3; and a gap detection section 4. The lens 2 and the optical receiver 3 are arranged to allow an optical axis when receiving reflection light from an edge 106 of the measurement target 100 by the optical receiver 3 to be crossed with an optical axis of light from the light projector, and also are arranged to allow a plain surface 20 including a light receiving surface of the optical receiver 3 and a main surface 21 of the lens 2 to cross with each other at a point of one straight line 22, to allow an in-focus object surface 23 to cross with the straight line 22, and to allow whole of the edge 106 to be included in the object surface 23. The gap detection section 4 detects a position of an incident point of reflection light 25 reflected against the edge 106 and made incident to a light receiving surface of the optical receiver 3 after passing the neighborhood of an edge 105 on the basis of a light receiving distribution on the light receiving surface of the optical receiver 3, so as to calculate a gap amount d of the measurement target 100.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a gap sensor that detects a gap amount of a measurement object.

  In recent years, an edge sensor that detects the position of an edge of an article such as a film or sheet has been put into practical use (for example, see Patent Document 1). As shown in FIG. 5, the edge sensor irradiates parallel light from a projector 1002 composed of a laser 1000 and a collimator lens 1001 toward the article 1005 and confronts the projector 1002 with the parallel light not blocked by the article 1005. The edge detector 1004 receives the light from a linear image sensor or the like arranged in such a manner that the boundary between the parallel light receiving area and the non-light receiving area (light-blocking area) in the light receiver 1003 is set as the edge position of the article 1005. It is intended to be detected.

  If such an edge sensor is applied, it is possible to realize a gap sensor that measures the amount of gap between two rollers, for example.

JP 2004-177335 A

  As described above, a gap sensor can be realized by applying the edge sensor technology. However, the transmission type gap sensor has a problem that when the gap becomes narrow, it is difficult to accurately measure the gap amount due to light interference and reflection.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide a gap sensor that can detect the gap amount of a measurement object without being affected by light interference.

  The gap sensor of the present invention includes a projector that irradiates light to a gap between measurement objects, a lens that collects the reflected light from the measurement object, and light that is collected by the lens to receive an electrical signal. A light receiving device for converting, and a gap detecting means for analyzing the output of the light receiving device to detect a gap amount of the measuring object, wherein the lens and the light receiving device are provided between the measuring object and the gap. Arranged so that the optical axis of the reflected light from the first edge far from the lens among the two opposing edges that are the boundary intersects the optical axis of the light from the projector The plane including the light receiving surface of the light receiver and the main surface of the lens intersect with one straight line, the object surface in focus intersects with the same straight line, and all the first edges are included in the object surface. The gap detecting means is arranged in front of From the distribution of light received on the light receiving surface of the light receiver, the light is reflected by the first edge farther from the lens among the two edges, and passes through the vicinity of the second edge closer to the lens. The position of the incident point of the reflected light incident on the light receiving surface is detected, and the gap amount of the measurement object is calculated from the position of the incident point.

Further, in one configuration example of the gap sensor of the present invention, the gap detection means sets the position where the received light amount is ½ with respect to the peak received light amount on the light receiving surface of the light receiver. It is detected as the position of the incident point of the reflected light that is reflected at the edge and passes through the vicinity of the second edge and enters the light receiving surface of the light receiver.
Further, in one configuration example of the gap sensor of the present invention, the measurement object is a transport mechanism that transports an object to be transported by upper and lower cylindrical rollers arranged in parallel so that the curved surfaces thereof face each other. And the projector projects light onto the curved surfaces of the two rollers, and the lens and the light receiver are a first roller farther from the lens and a second roller closer to the lens. Of the first roller, the optical axis when the reflected light from the first edge, which is a curved surface portion that is the shortest distance from the second roller, is received by the light receiver is the conveyance target. The gap detecting means is arranged so as to intersect with the flow direction of the object, the second edge of the second roller being a curved surface portion having the shortest distance from the first roller, and the first roller The amount of gap between the edges of And it is characterized in and.

  According to the present invention, since the gap amount of the measurement object can be clearly reflected in the light reception distribution on the light receiving surface of the light receiver, the gap amount of the measurement object can be detected without being affected by light interference. And high-accuracy gap detection can be realized.

It is a figure which shows the structure of the clearance gap sensor which concerns on embodiment of this invention. It is a perspective view explaining the light projector and measurement object of a gap sensor concerning an embodiment of the invention. It is a figure which shows typically the light reception amount on the light-receiving surface of the light receiver of the clearance gap sensor which concerns on embodiment of this invention. It is a figure explaining the detection method of the amount of gaps by the gap sensor concerning an embodiment of the invention. It is a block diagram which shows the structure of the conventional edge sensor.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram illustrating a configuration of a gap sensor according to an embodiment of the present invention, and FIG. 2 is a perspective view illustrating a projector and a measurement object of the gap sensor. The gap sensor is a projector 1 that irradiates light to the measurement object 100, a lens 2 that collects the reflected light from the measurement object 100, and the light collected by the lens 2 and converts it into an electrical signal. For example, it includes a light receiver 3 composed of a CCD (Charge-Coupled Device) sensor and a gap detector 4 that analyzes the output of the light receiver 3 and detects the gap amount d of the measurement object 100. In FIG. 2, the description of the lens 2 and the light receiver 3 is omitted for ease of description.

  The measurement object 100 is a transport mechanism that transports an object 10 such as a film, for example, and sandwiches the object 10 between two upper and lower cylindrical rollers 101 and 102 arranged in parallel so that their curved surfaces face each other. Thus, it is a mechanism that sends out the object 10 by the rotation of the rollers 101 and 102. The rollers 101 and 102 are arranged so that the rotation shafts 103 and 104 are parallel to each other. It is important for the transport mechanism to set the gap amount d between the two rollers 101 and 102 appropriately.

In the present embodiment, the flow direction of the object 10 to be conveyed such as a film conveyed by the measurement object 100 is MD (Machine Direction), the direction of the gap to be measured is TD (Transverse Direction), and the rollers 101 and 102 Let the direction of the rotating shafts 103 and 104 and the width direction of the object 10 to be conveyed be CD (Crcss Machine Direction).
FIG. 1 shows an optical system of a gap sensor viewed from a direction parallel to the flow direction MD of the object 10 to be conveyed. The projector 1 irradiates the curved surfaces of the two rollers 101 and 102 with light. The irradiation direction may not be parallel to the flow direction MD of the object 10 to be transported, and light may be irradiated from a direction inclined with respect to the flow direction MD. In particular, it is preferable that the rollers 101 and 102 are irradiated with light from obliquely above.

  According to the Scheimpflug principle, when the plane 20 including the light receiving surface 30 of the light receiver 3 and the main surface 21 of the lens 2 intersect with one straight line 22 (a straight line perpendicular to the paper surface of FIG. 1), the focus is achieved. It is known that the object planes 23 that meet each other also intersect on the same straight line 22. In the present embodiment, among the roller 102 farther from the lens 2 and the roller 101 closer to the lens 2, the curved surface portion of the roller 102 that is the shortest distance from the roller 101 is referred to as an edge 106, A curved surface located at the shortest distance from the roller 102 is called an edge 105. In the present embodiment, the light receiving system (lens 2 and light receiver 3) of the gap sensor is installed so that the entire upper edge 106 of the roller 102 is included in the object surface 23. Thereby, it is possible to focus on all the edges 106.

  In addition, the light receiving system of the gap sensor is arranged in an oblique direction with respect to the object surface 23 including the edge 106, and the optical axis of the light received by the light receiver 3 out of the reflected light from the edge 106 is the projector. The light receiving system is arranged so as to intersect the direction of the optical axis 24 of the light source light from 1. In the example of FIG. 2, the direction of the optical axis 24 of the light source light is made parallel to the flow direction MD of the object 10 to be transported for the sake of simplicity, but as described above, the direction of the optical axis 24 is the flow direction. The direction may not be parallel to the MD.

  When the gap sensor according to the present embodiment is always installed in the transport mechanism including the two rollers 101 and 102, it is necessary to set the positions of the projector 1, the lens 2, and the light receiver 3 so as not to interfere with the object 10 to be transported. It goes without saying that there is.

  In addition, as described above, the light receiver 3 is disposed so that the light receiving surface 30 is included in the plane 20, but it is only necessary to detect the position of the incident point where the specific reflected light is incident as described later. May be a two-dimensionally arranged light receiver, or a light receiving element along the RD direction in FIG. 1 (a direction parallel to the plane 20 and perpendicular to the flow direction MD of the object 10 to be conveyed). May be a light receiver (line sensor) arranged one-dimensionally.

  When light emitted from the projector 1 isotropically diffuses at the upper edge 106 of the roller 102, it is reflected by the edge 106, passes through the vicinity of the lower edge 105 of the roller 101, and enters the light receiving surface 30 of the light receiver 3. The light quantity of the reflected light 25 is ½ of the peak light quantity of the reflected light that passes through the part away from the edge 105 and enters the light receiving surface 30.

  FIG. 3 is a diagram schematically showing the amount of light received on the light receiving surface 30 of the light receiver 3 as viewed from the lens 2 side. Here, an example of the light receiver 3 in which the light receiving elements are two-dimensionally arranged is shown. On the light receiving surface 30 of the light receiver 3, a high light receiving amount region 31 and a low light receiving amount region 32 due to reflected light that passes through a portion away from the edge 105 and enters the light receiving surface 30 appear. The low light reception amount region 32 includes a semi-light reception amount region 33 in which the light reception amount is ½ with respect to the peak light reception amount of the high light reception amount region 31.

  FIG. 4 is a diagram for explaining a method of detecting the gap amount d according to the present embodiment. In the present embodiment, the angle θ1 formed by the plane 20 including the light receiving surface 30 of the light receiver 3 and the object surface 23 and the angle θ2 formed by the plane 20 and the main surface 21 of the lens 2 are known values. Accordingly, if the angle θ3 formed by the reflected light 25 reflected by the upper edge 106 of the roller 102, passing through the vicinity of the lower edge 105 of the roller 101 and entering the light receiving surface 30 and the plane 20 is known, the reflected light 25 is obtained. The angle θ4 formed by the object surface 23 can be calculated.

  As described above, the amount of the reflected light 25 (the amount of light received by the semi-light-receiving amount region 33) that passes through the vicinity of the edge 105 at the lower end of the roller 101 and enters the light-receiving surface 30 of the light receiver 3 Is half of the peak light amount of the reflected light that passes through the light-receiving surface 30 and enters the light-receiving surface 30 (the peak light-receiving amount of the high light-receiving amount region 31).

  Therefore, by analyzing the output of the light receiver 3 and detecting the semi-light-receiving amount region 33, the position in the RD direction of the incident point 26 on the light receiving surface 30 on which the reflected light 25 is incident can be detected. The distance L1 from the line 26 to the straight line 22 and the distance L2 from the incident point 26 to the center of the lens 2 can be calculated. From these distances L1 and L2 and the known angle θ2, the plane 20 including the light receiving surface 30 can be calculated. And the angle θ3 formed by the reflected light 25 can be calculated.

  As described above, since the angle θ1 formed by the plane 20 including the light receiving surface 30 and the object surface 23 is known, the angle θ4 formed by the reflected light 25 and the object surface 23 is calculated from the calculated angle θ3 and the known angle θ1. In addition, the distance L3 from the reflection point 27 of the reflected light 25 on the edge 106 at the upper end of the roller 102 to the straight line 22 and the incident point 26 on the light receiving surface 30 where the reflected light 25 enters from the reflective point 27. Can be calculated.

  In the present embodiment, since the distance L5 from the straight line 22 to the end face in the CD direction of the roller 102 is a known value, if the distance L3 from the reflection point 27 of the reflected light 25 on the edge 106 to the straight line 22 can be calculated, the roller L The distance L6 from the end face in the CD direction of 102 to the reflection point 27 can be calculated. From the distance L6 and the angle θ4, the gap amount d between the rollers 101 and 102 can be calculated.

  The gap detection unit 4 analyzes the output of the light receiver 3, and based on the light reception distribution on the light receiving surface 30 of the light receiver 3, the RD direction of the incident point 26 on the light receiving surface 30 on which the reflected light 25 is incident as described above. And the gap amount d between the rollers 101 and 102 may be calculated.

  In this way, in the present embodiment, the gap amount d between the rollers 101 and 102 can be clearly reflected in the light reception distribution on the light receiving surface 30 of the light receiver 3, so that measurement is not affected by light interference. The gap amount d of the object can be detected, and high-accuracy gap detection can be realized.

  The gap detection unit 4 can be realized by a computer having a CPU (Central Processing Unit), a storage device, and an interface, and a program for controlling these hardware resources. The CPU performs the processing described in this embodiment in accordance with a program stored in the storage device.

  The calculation method of the present embodiment uses the principle of triangulation, but there are various methods for calculating the gap amount d from the position of the incident point 26 on the light receiving surface where the reflected light 25 is incident. Can be considered. The present invention can be applied to these various calculation methods.

  For example, the angle θ4 formed by the reflected light 25 and the object surface 23 and the distance from the reflection point 27 to the straight line 22 for each distance L1 from the incident point 26 to the straight line 22 by setting the optical system of the rollers 101 and 102 and the gap sensor. It is possible to register the value of L3 in advance. Thus, when the gap detector 4 analyzes the output of the light receiver 3 and calculates the distance L1 from the incident point 26 to the straight line 22, the gap θ4 and the distance L3 corresponding to the distance L1 are acquired. be able to. As described above, since the distance L5 from the straight line 22 to the end surface of the roller 102 in the CD direction is a known value, if the distance L3 can be calculated, the distance L6 from the end surface of the roller 102 in the CD direction to the reflection point 27 can be calculated. The gap amount d between the rollers 101 and 102 can be calculated from the distance L6 and the angle θ4.

  The present invention can be applied to a gap sensor.

  DESCRIPTION OF SYMBOLS 1 ... Light projector, 2 ... Lens, 3 ... Light receiver, 4 ... Gap detection part, 10 ... Object of conveyance object, 100 ... Measurement object, 101, 102 ... Roller.

Claims (3)

A projector that irradiates light into the gap of the measurement object;
A lens for collecting the reflected light from the measurement object;
A light receiver that receives the light collected by the lens and converts it into an electrical signal;
A gap detecting means for analyzing the output of the light receiver and detecting the gap amount of the measurement object;
The lens and the light receiver receive reflected light from the first edge farther from the lens among the two opposing edges that are the boundary between the measurement object and the gap between the lens and the light receiver. Is arranged so that the optical axis of the light beam intersects with the optical axis of the light from the projector, and the plane including the light receiving surface of the light receiver and the main surface of the lens intersect with one straight line, and the object surface in focus is Intersecting in the same straight line, arranged so that all of the first edge is included in the object surface,
The gap detection means reflects from the light reception distribution on the light receiving surface of the light receiver at the first edge farther from the lens among the two edges, and in the vicinity of the second edge closer to the lens A gap sensor characterized by detecting the position of an incident point of reflected light that passes through the light receiving surface of the light receiver and calculates the gap amount of the measurement object from the position of the incident point. The gap sensor according to claim 1,
The gap detecting means reflects the position where the received light amount becomes ½ with respect to the peak received light amount on the light receiving surface of the light receiver by the first edge, and the vicinity of the second edge. A gap sensor, wherein the gap sensor detects a position of an incident point of reflected light that passes through and is incident on a light receiving surface of the light receiver. The gap sensor according to claim 1 or 2,
The measurement object is a transport mechanism that transports an object to be transported by two upper and lower cylindrical rollers arranged in parallel so that their curved surfaces face each other.
The projector irradiates light onto the curved surface of the two rollers,
The lens and the light receiver are at a shortest distance from the second roller of the first roller of the first roller farther from the lens and the second roller closer to the lens. The optical axis when the reflected light from the first edge that is a curved portion is received by the light receiver is arranged so as to intersect the flow direction of the object to be transported,
The gap detection means detects a gap amount between the second edge of the second roller, which is a curved surface portion having the shortest distance from the first roller, and the first edge. A gap sensor.

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