JP2007049489A - Imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an imaging apparatus which can be made compact and is used for a detector. <P>SOLUTION: The imaging apparatus is provided with: a light source apparatus 41 for illuminating an imaging target T; an imaging device 21 for converting an image formed on a light reception surface into an electric signal; an optical means for forming the image of the target T on the light reception surface of the imaging device 21; and a housing 1 for holding the light source apparatus 41 and housing the imaging device 21 and the optical means. The optical means comprises an incidence side reflecting mirror 33, an objective lens 30a arranged at a back stage of the incidence side reflecting mirror 33, an imaging lens 30b, and an outgoing side reflecting mirror 36 arranged at the back stage of the imaging lens 30b. Light made incident on the incidence side reflecting mirror 33 is emitted in a reverse direction to the time when it is incident. As the light on the side of the target T to the incidence side reflecting mirror 33 becomes reverse to the side of the imaging device 21 to the outgoing side reflecting mirror 36, the apparatus does not have a long shape only in one direction but can be made compact. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an imaging apparatus used in a detection apparatus that detects a state of an imaging target by image processing.

2. Description of the Related Art Conventionally, there has been provided an imaging device that is used for imaging an imaging target in a detection device that detects the state of the imaging target by performing image processing on an image obtained by imaging the imaging target (for example, Patent Document 1). reference). The imaging object is, for example, a jig such as an end mill in a machine tool such as a milling machine for precision machining or a workpiece, or a scanning probe in a three-dimensional measuring machine. Further, the state to be detected is a defect of the imaging target such as a position of the imaging target, a chip or a foreign matter attached to the surface.
JP 2001-269844 A

  Here, when the imaging target is small, it is necessary to arrange an optical system with high magnification and low distortion between the imaging target and the imaging device. However, such an optical system generally requires a long optical path length. Conventionally, due to the optical system as described above, the imaging device has a shape that is long in one direction, and the height and length of the installation location of the imaging device are required.

  The present invention has been made in view of the above-described reasons, and an object thereof is to provide an imaging apparatus that can be made compact.

  The first aspect of the present invention is an imaging device that is provided in a detection device that detects a state of an imaging target by performing image processing on an image obtained by imaging the imaging target and illuminates the imaging target. An imaging element that converts an image formed on the light receiving surface into an electric signal, an objective lens that receives light from the imaging target, and an imaging lens that passes light passing through the objective lens. Optical means for forming an image on the light receiving surface, and a housing for holding the illuminating means and housing the image pickup element and the optical means, and the optical means includes a plurality of optical elements each changing the direction of the optical axis. It includes a reversing unit that emits incident light in a reverse direction from a position different from the incident position, and the reversing unit includes a reflecting mirror that reflects the light that has passed through the imaging lens.

  According to the present invention, since the lights are opposite to each other on both sides of the reversing part, the shape is not long in one direction and can be made compact.

  According to a second aspect of the present invention, in the first aspect of the present invention, the optical means constitutes an object side telecentric optical system.

  According to the present invention, even if the distance between the optical means and the imaging target changes, the size of the image formed on the imaging element does not change, so the state of the imaging target can be detected accurately.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, the housing has two entrances that are directed toward the object to be imaged from different directions, and each of the light enters, and the optical means is incident. A semi-transparent element that transmits a part of light and reflects a part of the light, and two light guide paths that allow light incident from one incident port to enter the semi-transparent element from different directions, The semi-transparent element is a positional relationship in which the light that has passed through one light guide path and transmitted through the semi-mirror element and the light that has passed through the other light guide path and reflected by the half mirror element are incident on the imaging element. It is arranged.

  According to the present invention, an imaging target can be imaged from two directions with one image sensor. Therefore, the manufacturing cost can be reduced and the size can be reduced as compared with the case where two image sensors are provided.

  According to a fourth aspect of the present invention, in any one of the first to third aspects, the illuminating means illuminates a surface imaged by the imaging element in the imaging target.

  According to the present invention, it is possible to capture an image suitable for detecting a defect on the surface of the imaging target.

  According to a fifth aspect of the present invention, in any of the first to fourth aspects of the present invention, the housing is made of a conductive material, and is made of an insulating material. The holding body that supports the image sensor is interposed between the image sensor and the housing. It is characterized by providing.

  According to this invention, the arrival of radiation noise from the outside of the housing to the image sensor is suppressed by the housing. Further, since the housing and the image sensor are electrically insulated by the holding body, conduction of electromagnetic noise through the housing to the image sensor is also suppressed. Therefore, the influence of noise on the output of the image sensor is reduced.

  According to the present invention, the optical means for connecting the image to be imaged to the image sensor includes a plurality of optical elements each changing the direction of the optical axis and emits the incident light in a reverse direction from a position different from the incident position. By including the inversion part, the light is opposite to each other on both sides of the inversion part, so that it is not long in one direction and can be made compact.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  In the present embodiment, as shown in FIG. 1, for example, a light source device 41 made of a light emitting diode and holding a light source (not shown) for illuminating the imaging target T and housing a drive circuit (not shown) for driving the light source For example, a camera 2 including an imaging device 21 such as a charge coupled device (CCD), an objective lens 30a included in an optical unit that forms an image of the imaging target T on a light receiving surface of the imaging device 21, and imaging The lens 30b, the light source device 11, the camera 2, the objective lens 30a, and the housing 1 in which the imaging lens 30b is accommodated are provided. Hereinafter, the upper, lower, left, and right will be described with reference to FIG. 1A and the lower side of FIG.

  The objective lens 30a and the imaging lens 30b are respectively held by cylindrical lens holders 31 made of, for example, synthetic resin with the optical axes aligned.

  The housing 1 includes a light guide holder 32 that holds the lens holder 31, three light source holders 42 (only one is shown) that are provided on both the front and rear sides and the right side of the light guide holder 32, respectively, and hold the light source device 41. A base body 11 having a housing recess 11a in which the camera 2 is housed is provided on the upper surface, a light guide hole 12a in which the light guide holder 32 is held in a form in which the lens holder 31 is inserted, and a light source holder 42, respectively. The three light source holes 12b (only one is shown) are provided vertically, and are coupled to the base body 11 by, for example, screwing, and include the light guide holder 32 and the light source holder 42 and the base cover 12 that closes the housing recess 11a. . The base body 11, the base cover 12, the light guide holder 32, and the light source holder 42 are each made of metal.

  Each of the light source holders 42 protrudes from the outer peripheral surface of the lower end portion of the cylindrical main body portion 42a and the main body portion 42a that are held by, for example, screwing in a direction in which the light source device 41 emits light upward. 12 and a reflector 42c provided on the upper side of the main body 42a and a reflector holding part 42c that holds a light source side reflector 43 that reflects the light emitted from the light source device 41 toward the imaging target T. Become. An exit port 42d through which light from the light source device 41 reflected by the light source side reflecting mirror 43 exits is formed in a surface of the reflector holding unit 42c that is directed to the imaging target T. The exit port 42d is, for example, glass. It is closed by a window body 44 made of a transparent material. Each light source holder 42 has a bottomed cylindrical shape with an open bottom surface, and cover holes 45 and 55 having window holes 45a and 55a for emitting light that has passed through the window body 43 penetrated in the circumferential direction at the upper end. Is deposited. The light source holder 42 on the right side of the light guide holder 22 constitutes the backlight unit 4 together with the light source device 41, the light source side reflecting mirror 43, and the window body 44. The light source holders before and after the light guide holder 22 are the light source device and the light source. A front light unit 5 (see FIG. 2C) is configured together with the side reflecting mirror and the window. The front light unit 5 has a smaller projecting dimension from the upper surface of the base cover 12 than the backlight unit 4, and the window hole 55a of the cover 55 attached to the front light unit 5 is directed obliquely upward.

  The light guide holder 32 protrudes on the outer peripheral surface of the cylindrical main body portion 32a that is held by fitting the lens holder 31 with the inner surface of the main body portion 32a, for example, with the optical axis oriented in the vertical direction. A flange portion 32b that contacts the upper surface of the base cover 12 and an incident port 32d through which light enters at a position on the right surface that faces the emission port 42d of the light source holder 42 of the backlight unit 4 are provided. The reflecting mirror holding portion 32c. The reflecting mirror holding portion 32c holds an incident side reflecting mirror 33 that reflects light incident from the incident port 32d downward. The entrance 32d is closed by a window 34 made of a transparent material, like the exit 42d of the light source holder 42. Further, the light guide holder 32 is covered with a cover 35 having a bottomed cylindrical shape with an open bottom surface and a window hole 35a through which light passing through the window 33 is emitted in the circumferential direction. Is done. The light guide holder 32 and the light source holder 42 are coupled to the base cover 12 by, for example, screwing the flange portions 32b and 42b to the base cover 12, respectively.

  In addition, a reflector holder 37 that holds an exit-side reflecting mirror 36 that reflects downward light that has passed through the imaging lens 30b toward the right is attached to the lower side of the lens holder 31 by, for example, fitting. The optical axes of the objective lens 30 a and the imaging lens 30 b are in the vertical direction between the incident-side reflecting mirror 33 and the emitting-side reflecting mirror 36, and from the imaging target T side and the emitting-side reflecting mirror 36 relative to the incident-side reflecting mirror 33. Are also in the horizontal direction on the image sensor 21 side. That is, the leftward light incident on the incident-side reflecting mirror 33 above the lens holder 31 is reflected by the emission-side reflecting mirror 35 below the lens holder 31 and emitted rightward. The side reflecting mirror 36 constitutes a reversing unit in the claims. The incident-side reflecting mirror 33, the objective lens 30a, the imaging lens 30b, and the emitting-side reflecting mirror 36 constitute optical means in the claims. A set of the objective lens 30a, the imaging lens 30b, the lens holder 31, the light guide holder 32, the incident side reflection mirror 33, the window body 34, the emission side reflection mirror 36, and the reflection mirror holder 37 is hereinafter referred to as a light guide unit 3. .

  The camera 2 is placed on the right side of the reflecting mirror holder 37 with the light receiving surface of the image sensor 21 facing the left side, that is, the emitting side reflecting mirror 33, from the base cover 12 via the holding body 6 made of an insulating material such as synthetic resin. It is held in a suspended form, and there is a gap between the camera 2 and the base body 11. The holding body 6 is coupled to the base cover 12 and the camera 2 by, for example, screwing.

  The operation of this embodiment will be described. When the imaging target T is illuminated by at least one light source device 41 of the backlight unit 4 and the front light unit 5, the objective lens 30a and the imaging lens are incident through the window 34 of the light guide holder 32 and reflected by the incident-side reflecting mirror 33. An image of the imaging target T is formed on the imaging element 21 by the light that has passed through 30b and is reflected by the exit-side reflecting mirror 36. The image sensor 21 converts the formed image into an electric signal. The camera 2 is provided with an image signal generation circuit (not shown) that converts an electrical signal generated by the image sensor 21 into image data of a predetermined format, and the image data output from the image signal generation circuit is The image is transmitted to the image processing apparatus through the cable C connected to the camera. The base body 11 is provided with a cable insertion hole 11b through which the cable is drawn out, inside and outside the housing recess 11a.

  By the way, the light of the light source device 41 of the backlight unit 4 illuminates the imaging target T from the opposite side of the surface imaged by the imaging element 21, so that the outline of the imaging target T is clear in the image formed on the imaging element 21. Therefore, it is suitable for detecting the position of the imaging target T. Further, the light of the light source device of the front light unit 5 illuminates the surface of the imaging target T that is imaged by the imaging device 21, and therefore is suitable for detecting defects such as foreign matter adhesion and scratches on the surface of the imaging target T.

  Here, the inner diameter of the lens holder 31 is located at a position surrounding the lower focal point of the objective lens 30a, that is, the image-side focal point in a plane orthogonal to the optical axes of the objective lens 30a and the imaging lens 30b on the inner peripheral surface of the lens holder 31. An annular throttle protrusion 31a is formed inwardly so as to be smaller than other portions. Thus, an image side telecentric optical system is configured. Therefore, even if the position of the imaging target T is shifted in the direction in which the distance from the entrance 32d is changed (the left-right direction in FIG. 1), the size of the image formed on the imaging element 21 does not change. The state can be detected accurately.

  According to the above configuration, as shown in FIG. 2C, by providing the reversing unit composed of the incident side reflecting mirror 33 and the emitting side reflecting mirror 36, the incident side reflecting mirror 33 and the imaging target T side are arranged. The light is directed in the opposite direction from the image pickup device 21 side of the exit side reflecting mirror 36. Therefore, as shown in FIG. 2A, neither the incident-side reflecting mirror 33 nor the exit-side reflecting mirror 35 is provided, or as shown in FIG. 2B, only the incident-side reflecting mirror 33 is provided. In contrast, since it does not have a long shape in one direction, it can be made compact. In particular, when the magnification is increased, the distance from the imaging lens 30b to the image point becomes longer. Therefore, it is effective to dispose the emission-side reflecting mirror 35 at the subsequent stage of the imaging lens 30b as in the present embodiment.

  By the way, this embodiment is also used for detecting the position of a jig such as an end mill as an imaging target T in a machine tool such as a precision machining milling machine. In a machine tool, a high-power motor with power consumption of 100 kW may be used. In this case, the imaging device is exposed to strong radiation noise radiated from the motor. However, in the present embodiment, the housing 1 is made of metal to prevent the radiation noise from reaching the camera 2, and the camera 2 is supported on the housing 1 via the holding body 6 made of an insulating material. And the housing 1 are electrically insulated from each other to prevent conduction of electromagnetic noise from the housing 1 to the camera 2, so that the image sensor 21 and the image signal generation circuit of the camera 2 are not easily affected by noise.

  The optical element constituting the reversing unit is not limited to a mirror such as the incident-side reflecting mirror 33 and the emitting-side reflecting mirror 36 as long as the direction of the optical axis can be changed. For example, the imaging target T is illuminated. When monochromatic light is used as the light to be used, a prism may be used.

  In addition, two sets of light guide units 3 having different entrance directions 32d are provided, and a semi-transparent element that transmits a part of incident light and reflects a part thereof is added. Arranged in such a positional relationship that light passing through one light guide unit 3 and passing through the half mirror element and light reflected through the other light guide unit 3 and reflected by the half mirror element are incident on the image sensor 21. May be. Specifically, for example, as shown in FIG. 3, two sets of light guide units 3 are arranged in a direction in which the optical axes in the rear stage of the output side reflecting mirror 35 are orthogonal to each other, and the output side of one light guide unit 3 The camera 2 is arranged so that the imaging device 21 is positioned on the optical axis in the subsequent stage of the reflecting mirror 36. Also, the light-emitting units 3 are arranged in different directions with respect to the output-side reflecting mirrors 36 of the light guide units 3 and inclined at 45 degrees with respect to the optical axis at the rear stage of the output-side reflective mirrors 36 of the light guide units 3. A half mirror 38 is provided in the housing 1. The light emitted from the exit-side reflecting mirror 36 of one light guide unit 3 passes through the half mirror 38 and enters the image sensor 21 as indicated by an arrow A1, and from the exit-side reflector 36 of the other light guide unit 3. The emitted light is reflected by the half mirror 38 and is incident on the image sensor 21 of the camera 2 as indicated by an arrow A2. Further, in the example of FIG. 3, two sets of backlight units 4 that illuminate the imaging target T from the side opposite to the entrance 32 d are provided corresponding to each light guide unit 3 as indicated by arrows A 3 and A 4. If the said structure is employ | adopted, since the imaging target T can be imaged from two directions with the one camera 2, it will become possible to detect the position of the imaging target T three-dimensionally. Further, the manufacturing cost can be reduced and the size can be reduced as compared with the case where two cameras 2 are provided. The half mirror element is not limited to the half mirror 38, and for example, a half prism may be used.

  Furthermore, it is good also as a structure which irradiates the imaging object T directly with the light of the light source device 41 instead of providing the light source side reflective mirror 43. FIG.

It is a figure which shows embodiment of this invention, (a) is front sectional drawing, (b) is a top view, (c) is a left view. It is a figure which shows an effect same as the above, (a) (b) is a schematic block diagram which shows a mutually different comparative example, (c) is a schematic block diagram which shows embodiment of this invention. It is a perspective view which shows the principal part of another form same as the above.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Housing 4 Backlight unit 5 Front light unit 6 Holder 21 Image pick-up element 30a Objective lens 30b Imaging lens 33 Incident side reflecting mirror 36 Outgoing side reflecting mirror 38 Half mirror 41 Light source device T Imaging object

Claims (5)

An imaging device that is provided in a detection device that detects a state of an imaging target by performing image processing on an image obtained by imaging the imaging target, and images the imaging target,
Illuminating means for illuminating an imaging target, an imaging element for converting an image formed on a light receiving surface into an electrical signal, an objective lens for receiving light from the imaging target, and an imaging lens for passing light passing through the objective lens Optical means for forming an image to be imaged on the light receiving surface of the image sensor, and a housing for holding the illumination means and housing the image sensor and the optical means,
The optical means includes a plurality of optical elements that change the direction of the optical axis, respectively, and includes a reversing unit that emits incident light in a reverse direction from a position different from the incident position,
The inversion unit includes a reflecting mirror that reflects light that has passed through the imaging lens.   The imaging apparatus according to claim 1, wherein the optical means constitutes an object side telecentric optical system.   The housing has two entrances that are directed toward the object to be imaged from different directions, and each receives light, and the optical means includes a semi-transparent element that transmits a part of the incident light and reflects a part thereof, and And two light guide paths that allow light incident from one incident port to enter the semi-transparent element from different directions. The imaging element and the semi-transparent element pass through one light guide path and pass the semi-transparent element. 3. The light transmission device according to claim 1, wherein the transmitted light and the light that has passed through the other light guide path and reflected by the semi-transparent mirror element are both placed in a positional relationship to be incident on the imaging device. Imaging device.   The imaging device according to claim 1, wherein the illumination unit illuminates a surface of the imaging target imaged by the imaging device.   The imaging apparatus according to claim 1, wherein the housing is made of a conductive material, and includes a holding body that is made of an insulating material and is interposed between the imaging element and the housing to support the imaging element.

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