JP2006162465A - Optical sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical sensor having a simple constitution, capable of fully suppressing unevenness of light collection on its light-receiving surface, regardless of the surface conditions of the object to be measured, when using a light-receiving means having a plurality of pixels on the light-receiving surface. <P>SOLUTION: In the optical sensor, a diffusion sheet 7 is disposed between a light-receiving lens 2 and the light-receiving means 1, and light from the light-receiving lens 2 is made to diffuse and receive by the light-receiving surface 1a of the light-receiving means 1, thereby making the optical distribution of the light-receiving surface 1a uniform and making the unevenness in light collection small. Accordingly, the unevenness of light-collection on the light-receiving surface 1a can be fully suppressed, by using a simple structure, regardless of the surface conditions of the object to be measured M. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical sensor for measuring the displacement or presence of a measurement object.

  Conventionally, it has a light receiving lens and a light receiving means such as a CCD image sensor having a light receiving surface composed of a plurality of pixels, and the light received by the light receiving means is reflected by the light receiving lens by the light receiving lens. An optical displacement sensor that receives light on a surface and measures the displacement of a measurement object by a triangulation method is known.

In this way, when the light receiving means has a plurality of pixels, as shown in FIG. 4, when reflected light from the measurement object is received, depending on the surface state of the measurement object, the light receiving surface of the light receiving means Condensation unevenness (spot pattern) occurs. When this unevenness in light collection occurs, it becomes difficult to detect and discriminate the measurement object with high accuracy. As a conventional apparatus, the light receiving surface of the CCD image sensor is arranged along the displacement direction of the measurement object. It is known that each pixel is given a specific width, and a specific calculation for averaging the variation in light intensity is performed to remove the influence of light collection unevenness (for example, Patent Document 1). ).
JP-A-10-332335

  However, the conventional apparatus requires a specific operation and thus the configuration is complicated. Also, depending on the object to be measured, the unevenness of light collection cannot be sufficiently suppressed due to the surface state, and it is difficult to detect and discriminate with high accuracy. There was a case. The distance setting type photoelectric sensor for measuring the presence or absence of the measurement object has the same problem.

  The present invention solves the above-mentioned problems, and when using a light receiving means having a plurality of pixels on the light receiving surface, the light receiving surface has a simple configuration, and the light collecting surface has uneven light collection regardless of the surface state of the measurement object. An object is to provide an optical sensor that can be sufficiently suppressed.

  In order to achieve the above object, an optical sensor according to one configuration of the present invention includes a light receiving lens and a light receiving means having a light receiving surface composed of a plurality of pixels, and receives reflected light from a measurement object by the light receiving lens. The light is received on the light receiving surface of the means to measure the displacement or presence of the measurement object, and is provided between the light receiving lens and the light receiving means, and diffuses the light from the light receiving lens on the light receiving surface of the light receiving means. A diffusion sheet for receiving light is provided.

  According to this configuration, the light from the light receiving lens is diffused and received by the light receiving surface of the light receiving means by the diffusion sheet provided between the light receiving lens and the light receiving means, so that the light distribution on the light receiving surface is made uniform and condensed. Since the unevenness is reduced, it is possible to sufficiently suppress the uneven light collection on the light receiving surface with a simple configuration regardless of the surface state of the measurement object.

  Preferably, there is provided diffusion sheet position adjusting means for arranging the diffusion sheet at an arbitrary position in the optical axis direction between the light receiving lens and the light receiving means. In this case, an optimal amount of received light can be obtained by adjusting the position of the diffusion sheet according to the surface state of the measurement object.

  An optical sensor according to another configuration of the present invention includes a light-receiving lens and a light-receiving unit having a light-receiving surface including a plurality of pixels, and causes the light-receiving surface of the light-receiving unit to receive reflected light from the measurement object. A ground glass provided between the light receiving lens and the light receiving means for diffusing the light from the light receiving lens to receive light on the light receiving surface of the light receiving means. A dual glass is formed and formed with a filter coating on the other side.

  According to this configuration, the light from the lens is diffused by the ground glass on one side of the dual glass provided between the light receiving lens and the light receiving means and received on the light receiving surface of the light receiving means, and the light distribution on the light receiving surface is made uniform. Condensation unevenness is reduced, so that it is possible to sufficiently suppress light collection unevenness on the light receiving surface regardless of the surface state of the measurement object, and it is possible to filter light of any wavelength by the filter coating on the other surface. Therefore, it can be prevented from being affected by disturbance light. Further, since the dual glass in which the ground glass and the optical filter are integrated is used, the size of the sensor can be reduced.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram showing an optical displacement sensor according to the first embodiment of the present invention. This sensor has a light projecting lens 3, a light projecting element (not shown), a light receiving lens 2, and a light receiving means (image sensor) 1 having a light receiving surface composed of a plurality of pixels, and each part is housed in a holder 6. Has been. This sensor irradiates the measuring object M with a light projection beam from the light projecting element through the light projection lens 3, and receives the reflected light from the measurement object M on the light receiving surface 1 a of the light receiving means 1 with the light receiving lens 2. Thus, the displacement of the measuring object M, for example, the height shape is measured.

  The light receiving means (image sensor) 1 of this sensor is, for example, a one-dimensionally arranged linear image sensor mounted on a substrate 4 and having a surface shielded by an image sensor shield 5. The light projecting element is, for example, a laser diode (LD).

  This sensor is provided between the light receiving lens 2 and the image sensor 1, and includes a diffusion sheet 7 that diffuses light from the light receiving lens 2 and causes the light receiving surface 1 a of the image sensor 1 to receive the light. The diffusion sheet 7 is made of, for example, resin and has a fine halftone dot (concave / convex) surface, and the light receiving surface 1a receives light in a state where light from the light receiving lens 2 is scattered. Thus, since the light distribution on the light receiving surface 1a is made uniform by making the light diffused by the diffusion sheet 7, the light collection unevenness on the light receiving surface 1a becomes sufficiently small as shown in FIG.

  In this example, the diffusion sheet 7 of FIG. 1 is provided between the light receiving lens 2 and the image sensor shield 5, but may be provided between the image sensor shield 5 and the image sensor 1.

  The sensor further includes a diffusion sheet position adjusting means 8 for disposing the diffusion sheet 7 at an arbitrary position in the optical axis direction between the light receiving lens 2 and the light receiving means (image sensor) 1. The amount of received light is physically controlled by adjusting the position of the diffusion sheet 7. This position adjustment is performed mainly at the time of installation of the present sensor, depending on the surface state of the measurement object M, the installation status of the present sensor, and the like. In this example, the diffusion sheet position adjusting means 8 is composed of a spacer having a predetermined thickness provided between the diffusion sheet 7 and the image sensor shield 5. This spacer may be provided between the image sensor shield 5 and the light receiving surface 1a. Further, the position of the diffusion sheet 7 may be adjusted by changing the thickness of the diffusion sheet 7 itself.

  Thus, in the present invention, the light from the light receiving lens 2 is diffused by the diffusion sheet 7 provided between the light receiving lens 2 and the image sensor 1 and is received by the light receiving surface 1a of the image sensor 1, so that the light receiving surface 1a. The light distribution of the light receiving surface 1a is made uniform to reduce the light collection unevenness, and therefore the light collection unevenness of the light receiving surface 1a can be sufficiently suppressed with a simple configuration regardless of the surface state of the measurement object M. Thereby, an optical displacement sensor capable of highly accurate detection and discrimination can be obtained. Conventionally, diffusing on the light-projecting side is known as, for example, providing a diffuser on the light-emitting side of a liquid crystal surface light source device to emit scattered light, but sufficiently suppresses unevenness in light collection Therefore, it is not known at all to diffuse light on the light receiving side.

  Further, since the diffusion sheet 7 is arranged at an arbitrary position by the diffusion sheet position adjusting means 8, the optimum amount of received light can be obtained by adjusting the position of the diffusion sheet 7 according to the surface state of the measurement object M or the like. Obtainable.

Next, a second embodiment will be described.
FIG. 3 shows a configuration of an optical displacement sensor according to the second embodiment. In the second embodiment, a dual glass 17 is provided instead of the diffusion sheet 7 of the first embodiment. The dual glass 17 has a ground glass 14 formed on one surface for diffusing light from the light receiving lens 2 to receive light on the light receiving surface 1a of the light receiving means 1, and a filter coating 15 formed on the other surface. The frosted glass 14 makes the light distribution on the light receiving surface 1a uniform by making light scatter in the same manner as the diffusion sheet 7 of the first embodiment. The filter coating 15 is, for example, a band pass filter (BPF) that passes only light of an arbitrary wavelength. Other configurations are the same as those of the first embodiment.

  In the second embodiment, light from the light receiving lens 2 is diffused by the ground glass 14 on one surface of the dual glass 17 provided between the light receiving lens 2 and the image sensor 1 to be received by the light receiving surface 1a of the image sensor 1. Since the light distribution on the light receiving surface 1a is made uniform and the light collection unevenness is reduced, the light collection unevenness on the light receiving surface 1 can be sufficiently suppressed regardless of the surface state of the measurement object M, and the filter coating on the other surface. 15 enables filtering such as passing only light of an arbitrary wavelength, so that it is not affected by disturbance light or the like. Thereby, an optical displacement sensor capable of highly accurate detection and discrimination can be obtained. In addition, since the dual glass 17 in which the ground glass and the optical filter are integrated is used, the size of the sensor can be reduced.

  In each embodiment, a linear image sensor arranged one-dimensionally in the light receiving means 1 is used, but a CCD image sensor arranged in two dimensions may be used.

  In each embodiment, a diffusion sheet or dual glass is used for the optical displacement sensor. However, the diffusion sheet or dual glass may be used for a distance setting type photoelectric sensor that measures the presence / absence of a measurement object.

It is a disassembled perspective view which shows the optical displacement sensor which concerns on 1st Embodiment of this invention. It is a side view which shows a part of optical displacement sensor of FIG. It is a side view which shows the optical displacement sensor which concerns on 2nd Embodiment. It is a side view which shows the conventional optical displacement sensor.

Explanation of symbols

1: Light receiving means (image sensor)
1a: Light receiving surface 2: Light receiving lens 7: Diffusion sheet 8: Diffusion sheet position adjusting means 14: Ground glass 15: Filter coating 17: Dual glass M: Object to be measured

Claims (3)

A light receiving unit having a light receiving lens and a light receiving surface composed of a plurality of pixels, the reflected light from the measurement object is received by the light receiving surface of the light receiving unit by the light receiving lens, and the displacement or presence of the measurement object is measured; An optical sensor,
An optical sensor provided with a diffusion sheet that is provided between the light receiving lens and the light receiving means and diffuses the light from the light receiving lens and receives it on the light receiving surface of the light receiving means. The claim 1, further comprising:
An optical sensor comprising diffusion sheet position adjusting means for arranging the diffusion sheet at an arbitrary position in the optical axis direction between the light receiving lens and the light receiving means. A light receiving unit having a light receiving lens and a light receiving surface composed of a plurality of pixels, the reflected light from the measurement object is received by the light receiving surface of the light receiving unit by the light receiving lens, and the displacement or presence of the measurement object is measured; An optical sensor,
It is provided between the light receiving lens and the light receiving means, and is provided with a dual glass having a ground glass formed on one surface for diffusing light from the light receiving lens and receiving light on the light receiving surface of the light receiving means, and a filter coating on the other surface. Optical sensor.

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