JP2005311680A - Visual sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a visual sensor having no risk of generating a ghost image. <P>SOLUTION: An optical member 11 includes a translucent material having an incident plane 11a into which surrounding light L is incident, and a reflector 15 for reflecting the surrounding light L. An imaging means 13 images the surrounding light L reflected by the reflector 15. The optical member 11 has a concave 11b. The reflector 15 is a reflection layer formed on the concave 11b. The reflector 15 is of hyperboloid shape. The incident plane 11a of the optical member 11 is a spherical surface of which center is the focus f of the hyperboloid shape. The optical member 11 has a hole 11d disposed at the vertex of the rotational symmetry form of the reflector 15. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a visual sensor in which a wide range of ambient light is reflected by a reflecting portion and is imaged by an imaging means such as a CCD (Charge Coupled Device).

Conventionally, various omnidirectional vision sensors have been proposed, and for example, disclosed in Patent Document 1 and Patent Document 2. Such an omnidirectional visual sensor 1 reflects ambient light with a hyperboloidal reflection mirror 2 and images the surroundings with an imaging camera 3 (see FIG. 4).
JP-A-10-160463 JP 2000-128031 A

  The imaging camera 3 is disposed on the bottom wall portion 5 a of the case body 5. A cylindrical tube 6 made of a translucent material is provided on the side wall 5 b of the case body 5, and the reflection mirror 2 is disposed inside the tube 6. A lid body 7 is disposed in the upper opening 6 a of the cylindrical body 6, and the reflection mirror 2 is fixed to the lid body 7. The reflection mirror 2 has a hyperboloid shape, and is arranged so as to hang from the lid body 7 with the top of the hyperboloid shape facing downward.

  However, the omnidirectional visual sensor 1 has a problem that it cannot be provided at low cost because of the large number of parts. In particular, the cylindrical body 6 made of a translucent material does not have any action optically. Therefore, if the cylindrical body 6 can be eliminated, the number of parts can be reduced. Therefore, the applicant of the present application, as Japanese Patent Application No. 2003-339306, discloses an optical member 11 having an incident surface 11a on which ambient light L is incident and a reflective layer 15 that reflects ambient light L, and the ambient light reflected by the reflective layer 15. The visual sensor 10 having the imaging means 13 for imaging the light L has been proposed (see FIG. 5). The optical member 11 is made of a solid translucent material, and the reflective layer 15 of the optical member 11 has a hyperboloid shape. The incident surface 11 a of the optical member 11 is a spherical surface centered on the hyperboloid focus f of the reflective layer 15.

However, not only the ambient light L incident from the incident surface 11 a and reflected by the reflective layer 15 but also the ambient light M internally reflected by the incident surface 11 a of the optical member 11 and reflected by the reflective layer 15 is reflected by the imaging element 13. Since the image is captured, the ambient light M may become an unnecessary image (so-called ghost image).
The present invention further improves a visual sensor using an optical member made of a solid translucent material, and provides a visual sensor that does not cause a ghost image.

  According to the first aspect of the present invention, an optical member made of a solid translucent material having an incident surface on which ambient light is incident and a rotationally symmetric reflecting portion that reflects the ambient light, and An imaging means for imaging the ambient light reflected by the reflecting portion, wherein the optical member has a hole provided at the top of the rotationally symmetric shape of the reflecting portion. .

  In the present invention, as described in claim 2, the hole has an elongated shape along the axis of the rotationally symmetric body shape.

  According to a third aspect of the present invention, the optical member has a concave portion, and the reflective portion is a reflective layer formed in the concave portion.

  According to a fourth aspect of the present invention, a light shielding member is provided on at least a part of the outer peripheral surface of the optical member.

  It is possible to provide a visual sensor that has a small number of parts, is inexpensive, and is less likely to generate a ghost image.

Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. 1 and 2 show a first embodiment.
The visual sensor 10 includes an optical member 11, a case body 12, an image sensor 13 (imaging means), and a circuit board 14.

  The optical member 11 is made of a solid translucent resin (for example, polycarbonate), and includes a spherical incident surface 11a on which the ambient light L is incident and a hyperboloid-shaped concave portion 11b. The hyperboloid shape of the recess 11b is a rotationally symmetric body about the axis X. The incident surface 11a of the optical member 11 is a spherical surface centered on the hyperboloid focus f. The focal point f of the hyperboloid is located on the axis X. In this specification, the “spherical surface” is at least a part of the surface of the sphere, not the entire surface of the sphere.

  A reflective layer 15 (reflective portion) made of a metal film such as aluminum (Al) or chromium (Cr) is formed in the concave portion 11b of the optical member 11 by a method such as vapor deposition. A hole 11d is formed at the top of the hyperboloid shape of the recess 11b. The hole 11d has an elongated shape along the axis X of the hyperboloid shape. Since the ambient light M that causes the ghost image is reflected by the peripheral surface of the hole 11d, it does not reach the image sensor 13. The case body 12 includes a bottom wall portion 12a and a cylindrical side wall portion 12b, and the optical member 11 is fixed to the side wall portion 12b. The image sensor 13 is mounted on the circuit board 14 and is fixed to the bottom wall portion 12 b of the case body 12.

  The ambient light L enters the optical member 11 from the incident surface 11a, and is reflected by the reflective layer 15 (see FIG. 2). Since the ambient light L toward the hyperboloid-shaped focal point f is incident perpendicularly to the incident surface 11a, it is not refracted by the incident surface 11a. The ambient light L reflected downward by the reflective layer 15 exits from the emission surface 11 c and is imaged by the image sensor 13. The visual sensor 10 has a visual field C1 from 0 ° to an elevation angle of about 30 ° and a visual field C2 from 0 ° to a depression angle of 30 °. The image data output from the image sensor 13 is output to an image processing unit (not shown) and is used for recognition of obstacles around the visual sensor 10.

  FIG. 3 shows a second embodiment. In the second embodiment, only the shape of the optical member 31 and the position of the image sensor 13 are different, and the other configurations are the same as those of the first embodiment.

  The optical member 31 has a shape obtained by obliquely cutting the optical member 11 of the first embodiment, and includes a spherical incident surface 31a on which ambient light is incident, a hyperboloid concave portion 31b, and a planar inclined surface. 31e. The incident surface 31a of the optical member 31 is a spherical surface centered on the hyperboloid focus f. A hole 31d is formed at the top of the hyperboloid shape of the recess 31b. The hole 31d has an elongated shape along the axis X of the hyperboloid shape. A reflective layer 35 (reflective portion) is formed in the concave portion 31 b of the optical member 31. A light shielding layer 36 (light shielding member) made of black paint is formed on the planar inclined surface 31e. The image sensor 13 is arranged offset from the hyperboloid axis X by a predetermined distance d.

  According to the first and second embodiments, since there is no cylindrical body 6 that is conventionally necessary and the number of parts is small, assembly is simplified and the visual sensor 10 can be manufactured at low cost. In addition, since the holes 11d and 31d are provided, there is no possibility that a ghost image is generated. The reason why the holes 11d and 31d are elongated along the axis X is that the ambient light M causing the ghost image passes through the hyperboloid axis X. Further, by providing the light shielding layer 36 on the inclined surface 31e as in the second embodiment, ambient light that hits the inclined surface 31e and causes a ghost image can be blocked.

  Although the incident surfaces 11a and 31a of the optical members 11 and 31 of the first and second embodiments are spherical surfaces, they may be aspherical surfaces. Further, the reflection layers 15 and 35 are not limited to the hyperboloid shape, and may be a rotation target shape such as a conical shape, for example.

  Moreover, although the reflective part of each embodiment was the reflective layers 15 and 35 coated to the recessed parts 11b and 31b, you may insert-mold the reflective part which consists of a metal thin plate in the optical members 11 and 31, for example. Further, the imaging means may be, for example, a CMOS type imaging device. Further, a light shielding layer may be formed on the peripheral surfaces of the holes 11d and 31d, or the holes 11d and 31d may be filled with a light shielding resin.

Sectional drawing which shows 1st embodiment of this invention. Optical path explanatory drawing which shows 1st embodiment same as the above. Sectional drawing which shows 2nd embodiment of this invention. Sectional drawing which shows a prior art example. Sectional drawing which shows another prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Optical member 11a Incident surface 11b Recessed part 11d Hole part 13 Image pick-up element 15 Reflective layer (reflective part)
31 Optical member 31a Incident surface 31b Recessed part 31d Hole part 35 Reflective layer (reflective part)
36 Light-shielding layer (light-shielding member)

Claims (4)

An optical member made of a solid translucent material having an incident surface on which ambient light is incident and a rotationally symmetric reflecting portion that reflects the ambient light, and imaging that captures the ambient light reflected by the reflective portion A visual sensor having means,
The optical member has a hole provided at a top of the rotationally symmetric shape of the reflecting portion.   The visual sensor according to claim 1, wherein the hole has an elongated shape along an axis of the rotationally symmetric body shape.   The visual sensor according to claim 1, wherein the optical member has a concave portion, and the reflective portion is a reflective layer formed in the concave portion.   The visual sensor according to claim 1, wherein a light shielding member is provided on at least a part of an outer peripheral surface of the optical member.

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