JP4588525B2 - Imaging probe - Google Patents

Description

  The present invention relates to an image probe used in an image measuring machine that measures surface properties from image data obtained by imaging a workpiece, and in particular, the measurement of a three-dimensional measuring machine to make the three-dimensional measuring machine function as the image measuring machine. The present invention relates to an image probe used as a probe.

  In an image measuring machine that measures the dimensions of each part of the workpiece by directly imaging the workpiece with a CCD camera or by enlarging the image with a microscope and performing image processing and arithmetic processing on the obtained image data, an illumination light source that illuminates the workpiece The quality of the collected image data depends on the quality of the image, and the measurement accuracy is affected. For this reason, the light source that illuminates the workpiece is required to have the directionality and uniformity of the illumination light that can accurately capture the features of the workpiece.

  Currently, the illumination of image measuring machines is known as epi-illumination that irradiates light to the workpiece via the imaging optical system and ring illumination that irradiates light to the workpiece from the periphery of the imaging optical system. In the machine, these are often used together. In any system, a halogen lamp is used as a light source for illumination.

  By the way, in order to use a three-dimensional measuring machine as an image measuring machine, an image probe is conventionally used as a measuring probe of the three-dimensional measuring machine. However, many conventional image probes are fixed to the Z-axis (vertical axis), and replacement with other touch signal probes or the like is not easy. The reason is that the size of an image probe using a halogen lamp as illumination becomes large. Furthermore, in order to avoid the influence of heat from the light source, an optical fiber that guides light from the light source to the vicinity of the workpiece may be used. Therefore, the size of the light source, the heat generation of the light source, and the illumination light introduction path are obstacles to realizing an image probe that can be easily attached and detached. In addition, in order to enable imaging of an object to be measured from an arbitrary direction, an image probe swinging mechanism is required, but in addition to the above-mentioned illumination problems (light source and illumination light introduction path) There was a problem with the load resistance of the mechanism, and it was difficult to swing the image probe. Therefore, it has been difficult to realize an image probe that satisfies the probe change possibility (easy to attach and detach) and the arbitrary setting of the imaging direction.

  The present invention has been made in view of the above points, and an object thereof is to provide an image probe that is small, lightweight, easy to attach and detach, and capable of arbitrarily setting an imaging direction.

An image probe according to the present invention includes a solid-state imaging device that images a workpiece and outputs the image data, an imaging optical system that forms an image of the workpiece on the solid-state imaging device, and an incident illumination for the workpiece An epi-illumination light source composed of a semiconductor light-emitting element that generates illumination light, an illumination optical system that joins the illumination light from the epi-illumination light source to the imaging optical system and guides it to the workpiece via the imaging optical system, and these solids The imaging device, the imaging optical system, the epi-illumination light source and the illumination optical system are supported while maintaining a predetermined positional relationship, and the chassis is in close contact with the epi-illumination light source and the illumination optical system. And the chassis and / or the cover is formed of a magnesium alloy and has an overall weight of 500 grams or less, Movable three-dimensional original measuring any rotational angle operation and any angle of inclination operation are possible removably mounted via a mount portion as the tip above the measurement probe of the rotary joint of the probe head as possible, the mounting portion Has a connector function to connect / disconnect input / output signals and power to / from the epi-illumination light source and the solid-state imaging device by attaching / detaching to / from the probe head.

  The imaging optical system includes, for example, an objective lens arranged in the vicinity of the workpiece, an imaging lens arranged in the vicinity of the solid-state imaging device, and an optical axis between the objective lens and the imaging lens. The illumination optical system is configured to guide the illumination light from the epi-illumination light source to the half mirror and merge it with the imaging optical system.

  In a preferred embodiment of the present invention, there is further provided a ring illumination light source that is arranged so as to surround the image pickup optical system and that irradiates the work from the periphery of the image pickup optical system, and the epi-illumination light source and the ring The illumination light source is configured to be able to illuminate selectively or simultaneously. The epi-illumination light source and / or the ring illumination light source is preferably turned on only during imaging of the solid-state imaging device.

  Moreover, the illumination light from the epi-illumination light source and / or the ring illumination light source preferably illuminates the workpiece via a diffusion plate. The epi-illumination light source and / or the ring illumination light source is constituted by a plurality of semiconductor light emitting elements, for example. In this case, it is preferable that the plurality of semiconductor light emitting elements are turned on / off or controlled in brightness at once or for each block or independently. The epi-illumination light source and / or the ring illumination light source is, for example, a cartridge.

  According to the present invention, the solid-state imaging device, the imaging optical system, the epi-illumination light source, and the epi-illumination optical system are supported by the chassis while maintaining a predetermined positional relationship, and these are accommodated inside the cover. . In particular, in the present invention, since the epi-illumination light source is composed of a semiconductor light emitting element, the light source can be reduced in weight, and the amount of generated heat can be much smaller than when a halogen lamp is used. The chassis and / or the cover is made of a magnesium alloy that is lightweight and has a high heat dissipation effect. Therefore, according to the present invention, there is no big problem even if the epi-illumination light source is arranged close to other members, and the image probe of the present invention is reduced in size and weight (500 grams) by reducing the arrangement space of components. The following is possible:

  Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. 1A and 1B are views showing the appearance of an image probe according to one embodiment of the present invention, in which FIG. 1A is a front view and FIG. 1B is a side view. FIG. 2 is a cross-sectional view taken along line AA in FIG. The image probe 1 includes a main body 11 composed of optical parts and the like which will be described later, and a mount 12 that is provided at the upper end of the main body 11 and is detachably attached to a probe head of a coordinate measuring machine (not shown). And a ring illumination light source 13 attached to the lower end of the main body 11.

  The main body 11 is configured as follows. A chassis 23 extending in the vertical direction is accommodated in a cylindrical space formed by the front cover 21 and the rear cover 22, and various optical components and the like maintain the positional relationship in a predetermined positional relationship in the chassis 23. It is fixed in this way. An objective lens 24 that catches a workpiece (not shown) is disposed at the lower end of the chassis 23. Reflected light from the workpiece introduced into the main body 11 through the objective lens 24 passes through a half mirror 25 arranged to be inclined with respect to the optical axis, and is condensed by the imaging lens 26 to be CCD camera (solid state). An image is formed on the light receiving surface of the image pickup device 27. The objective lens 24, the half mirror 25, and the imaging lens 26 constitute an imaging optical system.

  On the other hand, an epi-illumination optical unit 28 is provided behind the CCD camera 27 so as to irradiate illumination light downward. The epi-illumination optical unit 28 includes an epi-illumination light source 31 composed of a plurality of semiconductor light-emitting elements, a condenser lens 32 mounted on the illumination light emission side of the epi-illumination light source 31, a diffuser plate 33, and a cylindrical shape that holds them. The illumination optical unit 35 is composed of the body portion 34 of the light source. The illumination light emitted downward from the epi-illumination optical unit 28 is introduced into the coupling optical unit 29. The coupling optical unit 29 holds a mirror 42 that converts the traveling direction of the diffused illumination light from the illumination optical unit 35 into a horizontal direction, a lens 43 that collects the illumination light via the mirror 42, and these. It is comprised from the cylindrical trunk | drum 44. FIG. The illumination light whose path has been converted in the horizontal direction by the coupling optical unit 29 is guided to the half mirror 25 of the imaging optical system, reflected by the half mirror 25, and the path is changed downward, and the work is passed through the objective lens 24. Incident lighting. The illumination optical system is configured by the illumination optical unit 35 and the coupling optical unit 29.

  FIG. 3 is a side sectional view of the chassis 23. The chassis 23 forms a space extending in the vertical direction for accommodating the imaging optical system. This space is divided into three in the vertical direction. The uppermost part is the accommodating part 51 of the CCD camera 27, the next is the accommodating part 52 of the imaging lens 26, and the lower end part is the accommodating part 53 of the half mirror 25. An annular support portion 54 that holds the epi-illumination optical unit 28 is provided on the back side at a position between the housing portions 52 and 53. In addition, a hole portion 55 to which the coupling optical unit 29 is coupled is formed on the back side of the housing portion 53.

  4A and 4B are diagrams showing details of the epi-illumination light source 31. FIG. 4A is a plan view seen from below, FIG. 4B is a side sectional view, and FIG. 4C is seen from the top. The top view and the same figure (d) are side views. As shown in the figure, the epi-illumination light source 31 includes a plurality of LEDs (light-emitting diodes) 62 that are semiconductor light-emitting elements that are two-dimensionally arranged on the bottom surface of a disk-shaped frame 61 whose edges rise downward. It is configured. Two disc-shaped printed circuit boards 64 and 65 are supported on the back side of the frame 61, that is, on the upper surface side, with a support 63. An LED 62 is mounted on the substrate 64, and an electronic component 66 constituting a drive circuit of the LED 62 is mounted on the substrate 65. The plurality of LEDs 62 are grouped into five as shown in FIG. A number written on each LED 62 indicates a group number. The LEDs 62 are configured to be independently drivable in units of groups.

  5A and 5B are views showing the ring illumination light source 13, wherein FIG. 5A is a partial cross-sectional view seen from the side, and FIG. 5B is a plan view seen from below. The ring illumination light source 13 includes an annular frame 71 that rises downward from the edge and has an inner bottom portion inclined in a mortar shape, and a plurality of LEDs 72 that are semiconductor light emitting elements disposed on the inner bottom portion of the frame 71. It is composed of As shown in FIG. 2, the ring illumination light source 13 surrounds the objective lens 24, and illuminates the workpiece with an appropriate illumination range and working distance from the periphery of the objective lens 24, so that the back surface thereof passes through a cylindrical attachment 73. The chassis 23 is detachably attached to the lower end portion. The attachment 73 may include a known telescopic lens barrel structure used for a zoom lens, and may automatically or manually move the ring illumination light source 13 to the optimum illumination position with respect to the workpiece.

  According to the image probe 1 configured in this way, the illumination light from the epi-illumination light source 31 passes through the diffusion plate 33 to become illumination light with uniform brightness, and is mixed with the imaging optical system by the coupling optical unit 29. The workpiece is irradiated as vertical incident illumination light through the objective lens 24. An image of the work is picked up by the CCD camera 27 and output to the outside as image data via the connector of the mount unit 12.

  The epi-illumination light source 35 of the epi-illumination optical unit 28 is made into a cartridge, and can be attached and replaced in a lump. For example, the epi-illumination light source 35 can be easily removed by configuring the epi-illumination optical unit 28 to be slidable downward with respect to the support portion 54 of the chassis 23. Moreover, the epi-illumination optical unit 28 itself has a structure in close contact with the chassis 23, and heat generated by the light source can be efficiently released to the chassis 23. For this reason, the chassis 23 and the covers 21 and 22 are good to use the magnesium alloy whose heat dissipation effect is higher than a plastic, for example. The magnesium alloy can be molded by a thixomolding method. The characteristics of magnesium alloy and other typical die casting materials are shown below.

[Table 1]
Magnesium alloy Aluminum alloy Zinc alloy Specific gravity 1.81 2.68 6.6
Tensile strength (Mpa) 240 331 283
Thermal conductivity (W / m * k) 51 96 113

  The magnesium alloy can be thinned to 0.6 to 1.2 mm, and has an electromagnetic shielding property as it is. Thermal conductivity is higher than plastic. By molding the chassis 23 and the covers 21 and 22 from a magnesium alloy, the weight can be reduced to a total weight of 500 grams or less (400 grams or less by further thinning), and at the same time, electromagnetic shielding and heat dissipation. Can also be increased.

  Thus, since the image probe 1 of this embodiment is lightweight, as shown in FIG. 6, it can be attached to the tip of the rotary joint 82 at the tip of the probe head 81 of the coordinate measuring machine via the mount portion 12. it can. The mount unit 12 holds the image probe 1 and supplies a video signal of a CCD camera, a power source of an illumination light source, and the like. The image probe 1 is held by the probe head 81 via the mount portion 12, and given an arbitrary angle of rotation and inclination. The probe head 81 is held on, for example, the Z axis of the coordinate measuring machine. Accordingly, by attaching the image probe 1 to the probe head 81 via the mount portion 12, various electrical signals are connected at the same time. When the ring illumination light source 13 is additionally used, the power supply voltage of the ring illumination light source 13 may be supplied via the connector 14 as shown in FIG.

  The two illumination light sources of the image probe 1, that is, the epi-illumination light source 31 and the ring illumination light source 13, are respectively dimmed and controlled by an illumination control device 91 as shown in FIG. The illumination control device 91 controls which one of the epi-illumination light source 31 and the ring illumination light source 13 is turned on / off, and both are turned on / off, and all the LEDs 62 and 72 constituting them are turned on / off / dimming control. Whether to turn on / off / dim control the LEDs 62 and 72 independently or to turn on / off / dim control for each block is determined, and each control is executed. For example, the epi-illumination light source 31 is divided into five blocks as shown in FIG. 4, and lighting / extinguishing / brightness adjustment is performed for each block. The ring illumination light source 13 can be similarly controlled. As the semiconductor light emitting element, an LD (laser diode) can be used in addition to the LED. The light-emitting colors of the semiconductor light-emitting elements can be used by aligning any color such as red, green, and white with the same color, or combining each color. A plurality of colors can be emitted, and an emission color suitable for the color of the work may be selected.

  The CCD camera 27 is controlled by a camera control device 92 shown in FIG. The illumination control device 91 controls the lighting of the illumination light sources 31 and 13 only during imaging by introducing an imaging signal from the camera control device 92. Thereby, the emitted-heat amount of the illumination light sources 31 and 13 can be suppressed to the minimum. The illumination control device 91 and the camera control device 92 can be controlled by a three-dimensional control device (not shown).

  The mount 12 is automatically attached / detached by the probe head 81 (auto probe change). However, when this automatic attachment / detachment function is not used, instead of the mount 12, for example, as shown in FIG. You may make it provide. When the shank unit 15 is provided, the image signal of the CCD camera 27, the power source of the illumination light sources 31 and 13, and the like may be input / output by a separately provided connector 16. In this case, the shank portion 15 of the image probe 1 is manually attached to the Z-axis of the coordinate measuring machine, and then the connector 16 is connected to connect various electrical signals. These operations are performed with one touch. The operability when attaching and detaching is excellent.

The following effects can be obtained by the image probe described above.
(1) It is possible to realize a small and lightweight image probe capable of auto probe change with the same operability as a conventional touch probe, so that contact / non-contact measurement with a CMM etc. can be performed continuously and automatically. become.
(2) Since it can be attached to the probe head with the same operability as a conventional touch probe, it is possible to operate the image probe at any rotation angle and tilt angle, and to measure the workpiece from any direction. The flexibility of workpiece measurement can be dramatically improved.
(3) In addition to these effects, the epi-illumination light source and the ring illumination light source can be arbitrarily switched, so that a high-quality image can be taken and the measurement accuracy can be improved.
(4) Since the illumination light source only needs to be turned on during imaging, heat generation can be suppressed, accuracy deterioration due to heat to the imaging system can be prevented, and measurement accuracy can be improved.
(5) The illumination light source is composed of a plurality of semiconductor light emitting elements, and each semiconductor light emitting element can be turned on / off and brightness controlled independently or for each block, so that illumination from any direction is possible. As a result, a high-quality image can be captured.
(6) Since the illumination light source can be integrated (made into a cartridge), maintenance and replacement work is facilitated.
(7) Since the chassis and the cover are made of a magnesium alloy, an exchangeable image probe having a weight of 500 grams or less can be realized, and measurement with the same operability as a conventional touch probe can be realized.

It is the front view (a) and side view (b) which show the external appearance of the image probe which concerns on one Example of this invention. It is AA sectional drawing in Fig.1 (a) of the image probe. It is sectional drawing of the chassis used for the image probe. It is a figure which shows the epi-illumination light source used for the image probe. They are a side fragmentary sectional view (a) and a lower plan view (b) showing a ring illumination light source used for the image probe. It is a perspective view which shows the probe head with which the image probe is mounted | worn. It is a block diagram which shows the control circuit of the image probe. It is the front view (a) and side view (b) which show the external appearance of the image probe which concerns on the other Example of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Image probe, 11 ... Main-body part, 12 ... Mount part, 13 ... Ring illumination light source, 14, 16 ... Connector, 15 ... Shank part, 21 ... Front cover, 22 ... Rear cover, 23 ... Chassis, 24 ... Objective lens , 25 ... half mirror, 26 ... imaging lens, 27 ... CCD camera, 28 ... epi-illumination optical unit, 29 ... coupling optical unit, 31 ... epi-illumination light source.

Claims (8)

A solid-state imaging device for imaging a workpiece and outputting the image data;
An imaging optical system for forming an image of the workpiece on the solid-state imaging device;
An epi-illumination light source comprising a semiconductor light-emitting element that generates illumination light for epi-illuminating the workpiece;
An illumination optical system that joins the illumination light from the epi-illumination light source to the imaging optical system and guides it to the workpiece via the imaging optical system;
The solid-state imaging device, the imaging optical system, the epi-illumination light source and the illumination optical system are supported while maintaining a predetermined positional relationship, and the chassis is in close contact with the epi-illumination light source and the illumination optical system. ,
And a cover for accommodating these,
The chassis and / or the cover is formed of a magnesium alloy,
With the total weight is less than 500 grams, via the mounting portion as a measurement probe tip above the rotary joint of the three-dimensionally movable arbitrary rotation angle operation and any inclination angle which can operate the probe head of the coordinate measuring machine Can be attached detachably,
The image probe according to claim 1, wherein the mount unit has a connector function for connecting / disconnecting an input / output signal and a power source to / from the epi-illumination light source and the solid-state imaging device by being attached to and detached from the probe head. The imaging optical system includes an objective lens arranged in the vicinity of the workpiece, an imaging lens arranged in the vicinity of the solid-state imaging device, and an inclination between the objective lens and the imaging lens with respect to the optical axis. With a half mirror,
The image probe according to claim 1, wherein the illumination optical system guides illumination light from the epi-illumination light source to a half mirror of the imaging optical system so as to join the imaging optical system. A ring illumination light source composed of a semiconductor light emitting element that is disposed so as to surround the imaging optical system and irradiates the workpiece from the periphery of the imaging optical system;
The image probe according to claim 1, wherein the incident illumination light source and the ring illumination light source are configured to be able to illuminate selectively or simultaneously.   The image probe according to claim 3, wherein the epi-illumination light source and / or the ring illumination light source is turned on only during imaging of the solid-state imaging device.   The image probe according to any one of claims 1 to 4, wherein illumination light from the epi-illumination light source and / or ring illumination light source illuminates the workpiece through a diffusion plate.   The image probe according to claim 1, wherein the epi-illumination light source and / or the ring illumination light source includes a plurality of semiconductor light-emitting elements.   The image probe according to claim 6, wherein the plurality of semiconductor light emitting elements are turned on / off or brightness controlled at a time, block by block, or independently.   The image probe according to claim 1, wherein the epi-illumination light source and / or the ring illumination light source is a cartridge.

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