JP2007155600A - Projector for measuring three-dimensional shape, and instrument for measuring three-dimensional shape - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a projector for measuring a three-dimensional shape that can project an optical pattern in a large light amount without changing the position of the optical pattern even when performing changeover of the optical pattern. <P>SOLUTION: The projector for measuring the three-dimensional shape comprises: a light source 12 for emitting light; a projection lens 56 for projecting the optical pattern toward a measuring object; and an optical path branching/changeover optical system for changing an optical path of light emitted from the light source 12 between the light source 12 and the projection lens 56 into either optical path out of two branched optical paths. The optical path branching/changeover optical system can change the optical path by moving a movable mirror 46. One optical path is provided with a pattern generation element for generating the optical pattern of a stripe pattern, and light passing through the optical path is the optical pattern of the stripe pattern to be projected from the projection lens 56. The other optical path is not provided with the pattern generation element, and light passing through the other optical path is projected from the projection lens 56 as the uniform optical pattern of illumination distribution. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a three-dimensional shape measuring apparatus for measuring a three-dimensional shape of a measurement target by analyzing a light pattern projected on the measurement target, and a three-dimensional shape for projecting a light pattern on the measurement target The present invention relates to a light projecting device for measurement.

  As a method of obtaining the three-dimensional shape of the measurement object by image analysis, a light pattern is projected onto the measurement object existing within a predetermined imaging field of view, and the deformation amount of the deformed light pattern according to the three-dimensional shape of the measurement object There is a method to analyze. Typical examples of this method include a phase shift method and a fringe analysis method.

  In the phase shift method, for example, a light pattern whose brightness changes in a sine wave shape is projected onto a measurement object, the phase of this light pattern is shifted by a certain angle and photographed three times or more, and the obtained images are compared with each other. By acquiring the deformation amount (phase shift) of the optical pattern, the three-dimensional shape of the measurement object is measured. Therefore, in the phase shift method, since light patterns having different phases must be projected onto the measurement object, it is necessary to switch between three or more light patterns.

  In the fringe analysis method (spatial fringe analysis method), as in the phase shift method, for example, a light pattern (striped light pattern) whose brightness changes in a sine wave shape is projected onto the measurement object, and the planar portion of the measurement object The three-dimensional shape of the measurement object is measured by acquiring the deformation amount (phase shift) of the light pattern as compared to when it is projected onto the object. In this method, since it is theoretically possible to measure a three-dimensional shape by projecting a striped light pattern once, it is not necessary to switch light patterns. However, in practice, measurement errors occur due to the color of the measurement object itself, shadows due to the unevenness of the measurement object, and the like, and it is necessary to reduce the influence of such factors. At this time, an image of the measurement object when a uniform light pattern (that is, light without a stripe pattern) is projected is acquired in advance, and the image of the measurement object when the stripe light pattern is projected is obtained mutually. A technique of suppressing the influence of the color of the measurement object by comparison is often used. For this reason, even when the fringe analysis method is used, it is necessary to switch the light pattern. Moreover, when the optical system state such as the angle at which the light pattern is projected changes between when the striped light pattern is projected and when the uniform light pattern is projected, the color of the measurement object or the Since the shadows and the like are different, the background cannot be removed. For this reason, it is necessary to use an optical system having the same relationship with the measurement object or the imaging unit as the light projecting unit.

  The light pattern used in the phase shift method and the light pattern used in the fringe analysis method include a method of generating a light pattern by transmitting light to a pattern generation element, a liquid crystal panel, etc. There is a method of generating a light pattern by controlling reflected light using a mirror device.

  The pattern generating element is formed by forming a light shielding part on a surface of a glass substrate or the like by a metal vapor deposition film and forming a light shielding part and a light projecting part at a constant pitch, and the pattern generating element shields a part of incident light. Thus, an optical pattern can be obtained. Therefore, in the case of using a pattern generation element in the phase shift method, in order to shift the phase of the optical pattern, it is necessary to move the pattern generation element precisely in accordance with it or replace it with a pattern generation element whose phase is shifted. Further, when using a pattern generation element in the fringe analysis method, the pattern generation element must be inserted into or extracted from the optical path.

  However, since the pattern pitch of the pattern generation element is generally several tens of μm, if the pattern generation element is moved in order to change the light pattern, the position of the pattern generation element is slightly changed each time the pattern generation element is moved. There is a risk of slipping. For this reason, when the light pattern transmitted through the pattern generating element is enlarged and projected onto the measurement object, there is a problem that the position reproducibility of the light pattern is lowered and the measurement accuracy of the measurement object is lowered.

  On the other hand, in the method using the liquid crystal panel, the light pattern can be switched by electrically controlling each pixel of the liquid crystal panel, so that no mechanical moving part is required. However, in order to obtain a practical three-dimensional shape measuring device, high-speed shooting is premised. However, the higher the shooting speed, the more light is required for the light pattern projected onto the measurement object. The liquid crystal panel is irradiated with a large amount of light. Therefore, when a liquid crystal panel is used, there is a problem that the liquid crystal panel deteriorates in a short period due to a large amount of light from the light source. In addition, in the liquid crystal panel, it has been difficult to obtain a resolution required in a desired area.

  DMD controls the reflection direction of incident light by moving micromirrors arranged for each pixel, thereby changing the light pattern. In the case of using the DMD, it is necessary to move each micromirror, but it is not necessary to move the entire DMD. However, in the case of using the DMD, the influence of the movement of the micromirror at the time of high-speed shooting becomes so large that it cannot be ignored, which causes noise. Further, even with DMD, it is difficult to obtain a resolution required in a desired area.

  The present invention has been made in view of the technical problems as described above, and the object of the present invention is that the position of the light pattern does not change even when the light pattern is switched, and the light is emitted with a large amount of light. The object is to provide a three-dimensional shape measuring light projecting device and a three-dimensional shape measuring device capable of projecting a pattern.

  A three-dimensional shape measurement light projecting device according to the present invention includes a light source that emits light, a projection lens that projects a light pattern toward a measurement object, and the light source between the light source and the projection lens. An optical path branching / switching optical system for switching an optical path of emitted light to one of a plurality of branched optical paths, and one of the optical paths passes through the optical path from the projection lens. The projected light pattern is light having a uniform illuminance distribution, and a pattern generating element for generating a striped light pattern is provided in another light path of the light paths to provide a striped light from the projection lens. It is characterized by projecting a pattern. In this specification, light having a uniform illuminance distribution and no pattern is also referred to as a (uniform) light pattern.

  In the three-dimensional shape measuring light projecting apparatus according to the present invention, the optical path is branched, a pattern generating element is provided on one optical path so that a striped light pattern can be projected, and the other optical path is projected. Light with a uniform illuminance distribution without providing a pattern generation element (so that a uniform light pattern can be projected and the light path can be switched to one of the light paths. Therefore, the pattern generation element can be moved or replaced. The light pattern to be projected can be switched between a striped light pattern and a uniform light pattern without shifting the position of the striped light pattern due to the position shift of the pattern generating element. The measurement accuracy of the original shape measurement can be improved.Because the pattern generation element is used, it is difficult to deteriorate even if a large amount of light is irradiated by the light source, Durability of the light projecting device becomes high in comparison with the case of using the LCD panel or DMD.

  In an embodiment of the three-dimensional shape measurement light projecting device of the present invention, the optical path branching / switching optical system is movable, and an optical path through which incident light passes is set to one of two optical paths. A movable mirror that can be switched, and a semi-transmissive semi-reflective element that transmits a part of the light passing through each light path and reflects a part of the light. The light transmitted through the semi-reflective element and the light reflected by the semi-transmissive semi-reflective element out of the light passing through the other optical path pass through the projection lens. As the transflective element, for example, there is a half mirror.

  In such an embodiment, since only one transflective element is required, it is emitted from the light projecting device as compared with the case where the movable part (movable mirror) is eliminated using two transflective elements. The decrease in the amount of light emitted can be reduced, and a light pattern with a large amount of light can be projected. In addition, since light that has passed through different optical paths passes through the same projection lens, it is possible to project a striped light pattern and a uniform light pattern using the same optical system, and to measure three-dimensional shape measurement. The accuracy is further improved.

  In another embodiment of the light projecting device for three-dimensional shape measurement of the present invention, the optical path branching / switching optical system is movable, and the optical path through which incident light passes is one of two optical paths. A first movable mirror that can be switched to a second movable mirror, and a second movable mirror that is incident on the projection lens so that the direction of light that has passed through one optical path and the direction of light that has passed through the other optical path are the same. And a movable mirror.

  In such an embodiment, a semi-transmissive / semi-reflective element is not required, so that a light amount loss due to the semi-transmissive / semi-reflective element can be eliminated, and a decrease in the amount of light emitted from the light projecting device can be extremely reduced. Therefore, it is possible to project a light pattern with a larger amount of light. In addition, since light that has passed through different optical paths passes through the same projection lens, it is possible to project a striped light pattern and a uniform light pattern using the same optical system, and to measure three-dimensional shape measurement. The accuracy is further improved.

  In each of the above embodiments, if a fixed mirror for bending the optical path is used, the optical path in the optical path branching / switching optical system can be bent easily and freely.

  Still another embodiment of the first three-dimensional shape measurement light projecting device of the present invention is such that the movable mirror switches the optical path by being inserted into or removed from the optical path from the light source. When the mirror is inserted in the optical path, it is switched to an optical path that does not pass through the pattern generation element, and when the movable mirror is removed from the optical path, it is switched to an optical path that passes through the pattern element. . According to this embodiment, when projecting a striped light pattern, the light does not pass through the movable member (that is, the movable mirror), so that the projection position accuracy of the striped light pattern is improved.

  Still another embodiment of the second three-dimensional shape measurement light projecting device of the present invention is such that the first movable mirror switches the optical path by being inserted into or removed from the optical path from the light source. When the first movable mirror is inserted into the optical path, the optical path is switched to not pass through the pattern generation element, and when the first movable mirror is removed from the optical path, the optical path is switched through the pattern element. The second movable mirror switches the optical path by being inserted into or removed from the optical path from the pattern generation element toward the projection lens, and when the second movable mirror is inserted into the optical path. When the light that has passed through the optical path that does not pass through the pattern generating element is directed to the projection lens, and the second movable mirror is removed from the optical path, the pattern It is characterized in that the light passing through the child is directed to the projection lens. According to such an embodiment, when projecting a striped light pattern, the light does not pass through the movable member (that is, the first movable mirror and the second movable mirror), so that the striped light pattern is projected. Position accuracy is improved.

  The three-dimensional shape measurement apparatus according to the present invention compares a light pattern projected on a measurement object, the illuminance of which changes periodically depending on the position, and a light pattern of uniform illuminance, thereby analyzing the measurement object. A three-dimensional shape measuring apparatus for measuring the three-dimensional shape of the light projecting apparatus according to the present invention, a line sensor for reading the two light patterns projected on the measurement object as an image, and the line sensor An image analysis unit that calculates height information of the measurement object based on the read images of the both light patterns.

  In the three-dimensional shape measuring apparatus according to the present invention, since the light projecting apparatus according to the present invention is used, the position of the striped light pattern projected from the light projecting apparatus is not easily shifted, and the three-dimensional shape is measured. The measurement accuracy of the measurement device can be improved. In addition, since a pattern generation element is used, the three-dimensional shape measuring device is more durable than a case where a liquid crystal panel or DMD is used in a light projecting device, even when a large amount of light is irradiated by a light source. Become.

  In addition, the component demonstrated above of this invention can be combined arbitrarily as much as possible.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the following examples.

  FIG. 1 is an external perspective view of a three-dimensional shape measuring apparatus 11 according to Embodiment 1 of the present invention. The three-dimensional shape measuring device 11 is a projection unit 12 (projection device) that projects a striped light pattern and a uniform light pattern, an imaging unit 13, and an image captured by the imaging unit 13 based on the image captured by the imaging unit 13. The image analysis / drive control unit 14 measures a three-dimensional shape. The light projecting unit 12 and the imaging unit 13 are installed above the transport unit 15 for placing and moving the measurement object 16.

  The three-dimensional shape measurement apparatus 11 projects a light pattern onto the measurement object 16 and analyzes the shape of the light pattern projected onto the measurement object 16, whereby the three-dimensional shape of the measurement object 16, for example, the measurement object. The depth of the recessed part provided in the surface of 16 and the height of a convex part, and those positions can be measured. The application of the three-dimensional shape measuring apparatus 11 is not particularly limited, but can be applied to an apparatus for inspecting a mounting board, for example.

  FIG. 2 is a block diagram showing the configuration of the three-dimensional shape measuring apparatus 11 according to the present invention. The imaging unit 13 reads the measurement object 16 onto which the light pattern is projected and acquires an image thereof, and includes one line sensor 26 and an optical system 25 such as a macro lens. The line sensor 26 of the imaging unit 13 is installed so that the axis in the main scanning direction is parallel to the placement surface of the transport stage 27 and perpendicular to the transport direction. By making the axis of the line sensor 26 in the main scanning direction and the mounting surface of the transport stage 27 parallel, the upper surface of the measurement object 16 can be imaged at a uniform magnification. Further, by making the axis of the main scanning direction of the line sensor 26 perpendicular to the conveyance direction, a right-angle portion is imaged as a right-angle portion in a two-dimensional image composed of a plurality of line images photographed while being conveyed.

  As shown in FIG. 2, the image analysis / drive control unit 14 is a computer including a CPU 33 and a RAM 34, a capture board 31 that captures an image from the imaging unit 13 as digital data, a controller 32 that controls the movement of the transport unit 15, and the like. is there. The image analysis / drive control unit 14 has a function of an image analysis unit that analyzes a light pattern included in an image captured by the imaging unit 13 by a fringe analysis method and calculates a three-dimensional shape of the measurement target 16. On the other hand, the image analysis / drive control unit 14 also has a function as a drive control unit that controls driving of the transport unit 15. Of course, the image analysis unit and the drive control unit may be configured by separate computers.

  The light projecting unit 12 is for projecting a light pattern onto the surface of the measurement object 16, and the detailed structure will be described later. The light pattern to be projected is switched between a striped light pattern 17 and a uniform light pattern (that is, uniform light without a striped pattern) 18. The striped light pattern 17 may be any pattern, such as a sine wave, a triangular wave, or a rectangular wave, as long as it has a periodicity according to the position and can specify the phase. It is assumed that a sinusoidal light pattern that contributes to improvement of the above is used. Here, the striped light pattern 17 and the uniform light pattern 18 are projected toward substantially the same area. For example, the light projecting unit 12 is installed at a distance of 460 mm from the upper surface of the transport stage 27, and the striped light pattern 17 and the uniform light pattern 18 have a rectangular shape (line L) having a length L of 140 mm or more and a width W of 2 mm or more. Is projected onto the area. Further, the striped light pattern 17 includes 2.5 black and white striped patterns per 1 mm length, and the striped pattern is in the width direction of the striped light pattern 17 for easy focusing. Is tilted about 6.7 °. Further, in the three-dimensional shape measuring apparatus 11, since it is necessary to photograph the measurement object 16 at a high speed, the light projecting unit 12 is required to have a large amount of light, and 10 in a bright portion of the uniform light pattern 18 or the striped light pattern 17. The illuminance is 10,000 lux.

  As shown in FIG. 3, the light projecting unit 12 is installed so that the optical axis thereof has a predetermined angle with respect to the optical axis of the imaging unit 13 installed perpendicularly to the upper surface of the transport stage 27. Yes. 3 is a perspective view of the light projecting unit 13, FIG. 4A is a perspective view in the X direction of FIG. 3, and FIG. 4B is a perspective view in the Y direction of FIG. As shown in FIGS. 3 and 4A and 4B, the optical axis of the light projecting unit 12 is α = 30 ° with respect to the direction perpendicular to the transport stage 27 when viewed from the front in the transport direction (X direction). When viewed from the side surface direction (Y direction), an angle of β = 45 ° with respect to a direction perpendicular to the transfer stage 27 is formed.

  As shown in FIG. 5, the striped light pattern 17 and the uniform light pattern 18 are alternately projected onto the measurement object 16. For example, a uniform light pattern 18 is projected while the measurement object 16 is stationary and photographed by the imaging unit 13, and then the light pattern is switched to project the striped light pattern 17 on the same portion of the measurement object 16. Then, the imaging unit 13 takes a picture. Then, the three-dimensional shape measuring apparatus 11 moves only the measurement object 16 while keeping it stationary, and projects a uniform light pattern 18 on the measurement object 16 that is stationary after moving the micro distance. The image is taken by the unit 13, then the light pattern is switched, and the striped light pattern 17 is projected onto the measurement object 16 and is taken by the imaging unit 13. As a result, a uniform light pattern irradiation image and a striped light pattern irradiation image on the measurement object 16 at a position slightly shifted from the previous photographing are acquired. By taking a large number of images by repeating such operations, the height and shape of the measurement object 16 are calculated based on the deviation of the light pattern projected onto the measurement object 16.

  The transport unit 15 is for horizontally moving the measurement object 16 in a direction perpendicular to the main scanning direction (longitudinal direction) of the line sensor 26 (hereinafter referred to as “sub-scanning direction”). For example, a servo stage 28 for driving the transfer stage 27, a linear scaler 29 for detecting the position of the transfer stage 27, and the like. The conveyance unit 15 can measure the three-dimensional shape of the entire measurement object 16.

  The operation of the three-dimensional shape measuring apparatus 11 will be described as follows. First, in accordance with a command from the image analysis / drive control unit 14, the servo motor 28 of the transport unit 15 sets the transport stage 27 to the initial setting position. This initial setting position determines the imaging start position in the sub-scanning direction when the imaging unit 13 images the measurement object 16, and the imaging area of the imaging unit 13 is placed on the conveyance stage 27 of the conveyance unit 15. It is preferable that the measured object 16 is positioned at the end in the sub-scanning direction.

  Then, the light projecting unit 12 projects a uniform light pattern 18 onto the measurement object 16. The imaging unit 13 scans a region on the surface of the measurement target 16 where the uniform light pattern 18 is projected, and acquires an image of the measurement target 16. The image acquired by the imaging unit 13 is transmitted to the image analysis / drive control unit 14 and converted into digital data by the capture board 31 of the image analysis / drive control unit 14. Next, the light projecting unit 12 is switched to the striped light pattern 17, and the light projecting unit 12 projects the striped light pattern 17 on the same position of the measurement object 16. The imaging unit 13 scans a region on the surface of the measurement target 16 where the striped light pattern 17 is projected, and acquires an image of the measurement target 16. The image acquired by the imaging unit 13 is transmitted to the image analysis / drive control unit 14 and converted into digital data by the capture board 31 of the image analysis / drive control unit 14. Then, the CPU 33 of the image analysis / drive control unit 14 erases the background information from the irradiation image of the striped light pattern 17 based on the irradiation image of the uniform light pattern 18, and the striped light pattern 17 from which the background information has been deleted. The height information of the measurement object 16 is calculated by analyzing the irradiation image.

  Here, the three-dimensional shape measuring apparatus 11 of the present embodiment is configured to use the spatial fringe analysis method when analyzing the striped light pattern 17 in the image. Thereby, each position in the scanning area (imaging area) of the measurement object 16 from one line image acquired by one line sensor 26 provided in the imaging section 13 once scanned. The height at can be determined.

  Then, the transport unit 15 moves the measurement object 16 by a predetermined distance in the sub-scanning direction under the control of the image analysis / drive control unit 14. As a result, the imaging region of the imaging unit 13 in the measurement object 16 and the positions of the uniform light pattern 18 and the striped light pattern 17 projected by the light projecting unit 12 are shifted in the sub-scanning direction by a predetermined distance. Become. Thereafter, the imaging unit 13 scans the measurement object 16 in a state where the uniform light pattern 18 is projected again and a state where the striped light pattern 17 is projected, and a line image is acquired. The line image obtained here includes an area of the measurement object 16 that is shifted in the sub-scanning direction by a predetermined distance from the previous scanning area. The obtained image is similarly transmitted to the image analysis / drive control unit 14, and three-dimensional information at each position in the new scanning area is obtained.

  Thus, the conveyance unit 15 moves the measurement object 16 again by a predetermined distance, the imaging unit 13 images the measurement object 16, and the image analysis / drive control unit 14 repeats the process of analyzing the line image. Thus, the three-dimensional shape of the entire measurement object 16 is measured.

  In the description of the above embodiment, the measurement object 16 is moved. On the contrary, the measurement object 16 is kept stationary, and the three-dimensional shape measurement apparatus 11 is moved intermittently to obtain a uniform light pattern 18. The measurement object 16 may be photographed by projecting the striped light pattern 17.

  Another imaging method may be as follows. While the uniform light pattern 18 is projected, the measurement object 16 is intermittently moved while the measurement object 16 is moved forward, and an irradiation image of the uniform light pattern 18 is photographed. Next, the measurement object 16 is moved backward. Then, the measurement object 16 may be stopped at the same position as the position where the measurement object 16 is stationary when moving forward, and an irradiation image of the striped light pattern 17 may be captured at each stationary position.

  Next, the structure of the light projecting unit 12 used in the above three-dimensional shape measuring apparatus 11 will be described in detail. FIG. 6 is a perspective view showing a specific structure of the light projecting unit 12, and FIG. 7 is a plan view thereof. Each component constituting the light projecting unit 12 is mounted on the base plate 40. A high-intensity light source 41 made of a metal halide lamp is installed at one end on the base plate 40. A collimating lens 42 for condensing the light emitted from the light source 41 and converting it into parallel light is provided in front of the light emission direction of the light source 41. Further, two integrator lenses 43 and 44 and a field lens 45 are provided in front of the collimating lens 42 on the optical path of parallel light collimated by the collimating lens 42. The integrator lenses 43 and 44 and the field lens 45 are installed in parallel to each other so as to be perpendicular to the light beam direction.

  The optical path branching / switching optical system includes a movable mirror 46, two fixed mirrors 48 and 51, and a half mirror 55. These mirrors 46, 48, 51, and 55 are positioned at the vertices of a rectangle. Has been placed. Of these mirrors 46, 48, 51, 55, the movable mirror 46 and the half mirror 55 are positioned in one diagonal direction, and the fixed mirror 48 and the fixed mirror 51 are positioned in the other diagonal direction. In addition, when the mirrors 46, 48, 51, and 55 are connected to each other in a rectangular shape, the mirror surfaces of the mirrors 46, 48, 51, and 55 are in the direction in which they are connected to each other. At an angle of 45 ° with respect to each other and are arranged parallel to each other.

  This optical path branching / switching optical system is arranged so that the light transmitted through the field lens 45 is incident on the movable mirror 46 at an angle of 45 °, and is fixed on a line extending straightly from the light incident on the movable mirror 46. One of the mirrors 51 and 48 is disposed, and the other of the fixed mirrors 51 and 48 is disposed in a direction in which light incident on the movable mirror 46 is reflected.

  The movable mirror 46 is rotated by a drive mechanism 47. By rotating the movable mirror 46, the movable mirror 46 is inserted into the optical path of the light transmitted through the field lens 45, or the optical path. Can be extracted from. The arrangement of the optical path branching / switching optical system is in a state where the movable mirror 46 is inserted in the optical path.

  The drive mechanism 47 for rotating the movable mirror 46 has the following structure. The movable mirror 46 is attached to the opening portion of the movable plate 60, and the outer peripheral portion is fixed to the movable plate 60. A shaft rod 61 is provided on both side surfaces of the base of the movable plate 60, and the shaft rod 61 is rotatably supported by a support frame 62 fixed on the base plate 40. Therefore, the movable plate 47 can rotate around the shaft rod 61. A motor 64 such as a pulse step motor or a servo motor is attached to the support frame 62, and a pinion 65 of the motor 64 is engaged with a gear 63 fixed to one shaft rod 61. Therefore, when the motor 64 is driven, the movable mirror 46 rotates around the shaft bar 61 together with the movable plate 47. In the projector 12, the movable mirror 46 can be rotated together with the movable plate 47 by driving the motor 64. Then, the drive mechanism 47 inserts the movable mirror 46 into the optical path between the field lens 45 and the fixed mirror 51 so as to form an angle of 45 ° with respect to the optical path, or in front of the field lens 45. It can be extracted from the optical path. In order to insert the movable mirror 46 at an accurate angle of 45 °, for example, a stopper that contacts the movable plate 60 may be provided when the movable mirror 46 has an angle of 45 °.

  As shown in FIG. 9B, the integrator lenses 43 and 44 are collective lenses in which a plurality of lens cells are arranged vertically and horizontally, and work to spread and superimpose the light beams that have passed through the lens cells in the same region. do. FIG. 10 is a principle diagram illustrating the function of the integrator lenses 43 and 44, and the light flux that has passed through each lens cell of the integrator lens 43 is spread and superimposed on the entire integrator lens 44. Further, the light flux that has passed through each lens cell of the integrator lens 44 is spread and superimposed on the entire pattern generation element 54. Therefore, the pattern generating element 54 is irradiated with extremely uniform light, and the light transmitted through the pattern generating element 54 becomes a uniform striped light pattern 17. The striped light pattern 17 generated by the pattern generation element 54 is incident on the half mirror 55, and a part thereof is reflected by the half mirror 55, and then enlarged and projected onto the measurement object 16 by the projection lens 56. Therefore, when the movable mirror 46 is extracted from the optical path, uniform light of the striped light pattern 17 is emitted from the light projecting unit 12.

  FIG. 8B is a schematic diagram showing the path of light when the movable mirror 46 is inserted in the optical path. As shown in FIGS. 7 and 8B, when the movable mirror 46 is inserted in the optical path, the light that has passed through the field lens 45 and entered the movable mirror 46 is reflected by the movable mirror 46. The light path is bent by 90 ° and enters the fixed mirror 48. Since the field lens 49 is disposed between the fixed mirror 48 and the half mirror 55, the light incident on the fixed mirror 48 is bent 90 ° in the direction of the light by the fixed mirror 48 and transmitted through the field lens 49. Incident on the half mirror 55. A part of the light incident on the half mirror 55 is reflected by the half mirror 55, and a part of the light passes through the half mirror 55 and is emitted from the projection lens 56 to the outside. Therefore, when the movable mirror 46 is inserted in the optical path, the light of the uniform light pattern 18 having no pattern is emitted from the light projecting unit 12.

  A field lens 52 is disposed between the fixed mirror 51 and the half mirror 55, and a pattern generation element 54 is disposed in front of the field lens 52 and is held by the pattern generation element support 53. The pattern generation element 54 is a glass plate or a heat-resistant transparent resin film provided with a light-shielding portion made of a metal vapor-deposited film and a slit-like light-transmitting portion therebetween.

  FIG. 8A is a schematic diagram showing the path of light when the movable mirror 46 is extracted from the optical path. When the movable mirror 46 is extracted from the optical path, the light transmitted through the field lens 45 enters the fixed mirror 51 and is reflected by the fixed mirror 51, so that the optical path is bent by 90 °. The light reflected by the fixed mirror 51 passes through the field lens 52 and is applied to the pattern generation element 54.

  According to such a light projecting unit 12, it is possible to switch between the striped light pattern 17 and the uniform light pattern 18 by moving the movable mirror 46 and switching the light path through which the light passes. That is, it is not necessary to move or replace the pattern generation element 54. Therefore, even if the light projected from the light projecting unit 12 is switched between the striped light pattern 17 and the uniform light pattern 18 many times, the position of the striped light pattern 17 is not shifted, and precise three-dimensional shape measurement is performed. Can be performed. Moreover, since the pattern generating element 54 used here is resistant to heat, it is not easily damaged even when irradiated with a large amount of light and has high durability.

  FIGS. 11A and 11B show a comparative example in which a movable part is eliminated by using a half mirror 91 instead of the movable mirror 46 in the optical path branching / switching optical system. In such a comparative example, one optical path is blocked by the shutter 92 or 93, and the optical path is switched as shown in FIG. 11 (a) or FIG. 11 (b). That is, as shown in FIG. 11B, when the optical path between the half mirror 91 and the fixed mirror 51 is blocked by the shutter 92, a part of the light incident on the half mirror 91 is reflected by the half mirror 91 and fixed. The light enters the mirror 48. The light incident on the fixed mirror 48 is reflected by the fixed mirror 48 and enters the half mirror 55, and a part of the incident light passes through the half mirror 55. 11A, when the optical path between the half mirror 91 and the fixed mirror 48 is blocked by the shutter 93, a part of the light incident on the half mirror 91 is transmitted through the half mirror 91 and fixed. Incident on the mirror 51. The light incident on the fixed mirror 51 is reflected by the fixed mirror 51, further passes through the pattern generation element 54 and enters the half mirror 55, and part of the incident light is reflected by the half mirror 55.

  Considering the case where light having a light intensity of 100 is incident in the comparative example, the amount of incident light is reduced by half by passing through the two half mirrors 91 and 55. The intensity decreases to 25 (25% of the amount of incident light). However, when the light passes through the optical path provided with the pattern generating element 54, the light intensity in the bright part of the striped light pattern 17 is considered.

  On the other hand, since only one half mirror 55 is used in the present embodiment, the light of the emitted light is passed through any of the optical paths as shown in FIGS. 8 (a) and 8 (b). The intensity is 50 (50% of the amount of incident light). However, when the light passes through the optical path provided with the pattern generating element 54, the light intensity in the bright portion of the striped light pattern 17 is considered. Therefore, according to the present embodiment, the striped light pattern 17 and the uniform light pattern 18 can be projected with high illuminance.

  Furthermore, in this embodiment, since the optical path length does not change even when the optical path is switched, the field lens 49 and the field lens 52 having the same curvature can be used, and the design is facilitated. Further, in this embodiment, when the striped light pattern 17 is projected, the light passes through the movable mirror 46, so that the shading when moving the movable mirror 46 and the aging of the drive mechanism unit 30 are achieved. Even if the movable mirror 46 is displaced due to excessive wear or the like, the projection position of the striped light pattern 17 is not affected, and the projection position accuracy of the striped light pattern 17 is increased.

  FIG. 9A shows the shape of an integrator lens 94 generally used in a data projector, and FIG. 9B shows the shape of the integrator lenses 43 and 44 used in this embodiment. Yes. In an integrator lens 94 generally used in a data projector, the aspect ratio of each lens cell is H: D = 3: 4. However, in the integrator lenses 43 and 44 used in the present embodiment, the aspect ratio of the lens cell. The ratio is H: D = 1: 3, which is horizontally long. In applications such as the present embodiment, by making the lens cell use such a horizontally long shape, the loss due to the boundary portion between the lens cells can be reduced, and the efficiency can be improved.

  In the first embodiment, the drive mechanism 47 is inserted into and removed from the optical path by rotating the movable mirror 46. However, the drive mechanism 47 may be removed from the optical path by moving the movable mirror 46 in parallel. Further, the actuator of the drive mechanism unit 47 is not limited to a motor, and a piezoelectric element or the like may be used.

  12A and 12B are schematic views showing an optical path branching / switching optical system of the light projecting unit 12 used in the second embodiment of the present invention. Since the other points are the same as those of the three-dimensional shape measuring apparatus according to the first embodiment, description thereof is omitted.

  In the second embodiment, a movable mirror 66 is used instead of the half mirror 55 of the first embodiment. Similarly to the movable mirror 46, the movable mirror 66 is inserted into or removed from the optical path by rotating or translating using the drive mechanism.

  In the case of the second embodiment, as shown in FIG. 12A, if the movable mirror 46 is removed from the optical path and the movable mirror 66 is inserted in the optical path, the optical path on which the pattern generation element 54 is arranged is changed. Since the light passes, the light projecting unit 12 projects a striped light pattern 17.

  Further, as shown in FIG. 12B, if the movable mirror 66 is removed from the optical path and the movable mirror 46 is inserted into the optical path, the light passes through the optical path where the pattern generating element 54 is not disposed. A uniform light pattern 18 is projected from the light projecting unit 12.

  Also in this embodiment, since the striped light pattern 17 and the uniform light pattern 18 can be switched without moving the pattern generation element 54, the position of the striped light pattern 17 is not shifted, and the striped light pattern is precisely set. 17 can be projected.

  Further, in the case of Example 2, since the half mirror is not used, the light intensity of the emitted light is 100 (100% of the incident light amount) when passing through any of the optical paths, and the striped light pattern with high illuminance. 17 or a uniform light pattern 18 can be projected.

  In the second embodiment, the moving direction of the movable mirror 46 and the movable mirror 66 is not particularly limited. For example, the movable mirrors 46 and 66 may be translated in a direction perpendicular to the paper surface of FIG. However, if they are moved in the same direction, the movable mirror 46 and the movable mirror 66 can be moved simultaneously by one drive mechanism 47, and the structure is simplified. Further, the movement of the movable mirror 66 is changed from the illustrated example of the second embodiment, and the movable mirrors 46 and 66 are removed from the optical path when the striped light pattern 17 is projected, and the movable mirror 66 is projected when the uniform light pattern 18 is projected. 46 and 66 are inserted into the optical path, and the striped light pattern 17 and the uniform light pattern 18 are directed upward in FIGS. 12A and 12B (the direction in which the light transmitted through the pattern generating element 54 goes straight). May be projected. According to such a modification, since the movable mirrors 46 and 66 are removed from the optical path when the striped light pattern 17 is projected, the projection position accuracy of the striped light pattern 17 is increased.

  FIGS. 13A and 13B are schematic views showing an optical path branching / switching optical system of the light projecting unit 12 used in Embodiment 3 of the present invention. Since the other points are the same as those of the three-dimensional shape measuring apparatus according to the first embodiment, description thereof is omitted.

  In the third embodiment, a fixed mirror 67 is used instead of the half mirror 55 of the first embodiment, and the fixed mirror 67 is disposed at a position close to the pattern generation element 54 (may be a position far from the pattern generation element 54). . Then, by using the fixed mirror 68 and the movable mirror 69, the light reflected by the fixed mirror 48 through the optical path where the pattern generating element 54 is not disposed passes through the pattern generating element 54 and is reflected by the fixed mirror 67. Thus, the light is incident on the projection lens 56 in the same manner as the light.

  In the case of the third embodiment, as shown in FIG. 13A, if the movable mirrors 46 and 69 are removed from the optical path, the light passes through the optical path where the pattern generating element 54 is arranged. A striped light pattern 17 is projected from the portion 12.

  Further, as shown in FIG. 13B, if the movable mirrors 46 and 69 are inserted in the optical path, the light passes through the optical path where the pattern generating element 54 is not arranged. A uniform light pattern 18 is projected.

  Also in this embodiment, since the striped light pattern 17 and the uniform light pattern 18 can be switched without moving the pattern generation element 54, the position of the striped light pattern 17 is not shifted, and the striped light pattern is precisely set. 17 can be projected.

  Further, in the case of Example 3, since a half mirror is not used, the light intensity of the emitted light is 100 (100% of the incident light amount) when passing through any optical path, and the striped light pattern with high illuminance. 17 and a uniform light pattern 18 can be projected, and a large amount of light can be maintained.

  In the case of the third embodiment, when a striped light pattern is projected, the movable mirrors 46 and 69 are out of the optical path and light does not pass through the movable parts (movable mirrors 46 and 66) (in particular, the pattern). Since the light after passing through the generation element 54 does not pass through the movable part), the striped light pattern is not affected by the movable part, and there is an advantage that the projection position accuracy of the striped light pattern is maintained.

  However, in the arrangement shown in FIG. 13, the optical path length differs between the optical path that passes through the pattern generation element 54 and the optical path that does not pass through the pattern generation element 54. In this case, the focal length of the field lens 49 and the field lens 52 is different. The design becomes complicated, such as the need to use different lenses.

  In each of the above embodiments, the optical path is switched by moving the movable mirror 46 in and out of the optical path, but the optical path is changed by changing the direction of light reflection by the movable mirror 46 by rotating the movable mirror 46. You may make it switch.

FIG. 1 is an external perspective view of a three-dimensional shape measuring apparatus according to Embodiment 1 of the present invention. FIG. 2 is a block diagram showing a configuration of the same three-dimensional shape measuring apparatus. FIG. 3 is a schematic perspective view showing the arrangement of the light projecting units. 4A is a view in the X direction of FIG. 3, and FIG. 4B is a view in the Y direction of FIG. FIG. 5 is a schematic diagram illustrating a state in which the light pattern projected from the light projecting unit is alternately switched between a striped light pattern and a uniform light pattern. FIG. 6 is a perspective view illustrating a specific structure of a light projecting unit used in the three-dimensional shape measuring apparatus according to the first embodiment. FIG. 7 is a plan view of the light projecting unit shown in FIG. FIG. 8A is a schematic diagram showing a state of the optical path branching / switching optical system when a striped light pattern is emitted from the light projecting unit. FIG. 8B is a schematic diagram illustrating a state of the optical path branching / switching optical system when a uniform light pattern is emitted from the light projecting unit. FIG. 9A is a front view showing an integrator lens for a data projector, and FIG. 9B is a front view showing an integrator lens used in the light projecting unit of the first embodiment. FIG. 10 is a principle diagram illustrating the function of the integrator lens used in the light projecting unit of the first embodiment. It is a schematic diagram which shows the optical path branching / switching optical system in a comparative example. FIG. 12A is a schematic diagram illustrating a state of the optical path branching / switching optical system when a striped light pattern is emitted from the light projecting unit in the second embodiment. FIG. 12B is a schematic diagram illustrating a state of the optical path branching / switching optical system when a uniform light pattern is emitted from the light projecting unit in the second embodiment. FIG. 13A is a schematic diagram illustrating a state of the optical path branching / switching optical system when a striped light pattern is emitted from the light projecting unit in the third embodiment. FIG. 13B is a schematic diagram illustrating a state of the optical path branching / switching optical system when a uniform light pattern is emitted from the light projecting unit in the third embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Three-dimensional shape measuring device 12 Light projection part 13 Imaging part 14 Image analysis and drive control part 15 Conveyance part 16 Measurement object 17 Stripe pattern light pattern 18 Uniform light pattern 27 Conveyance stage 41 Light source 42 Collimating lens 43, 44 Integrator lens 45 field lens 46 movable mirror 47 drive mechanism 48 fixed mirror 49 field lens 51 fixed mirror 52 field lens 54 pattern generation element 55 half mirror 56 projection lens 60 movable plate 66 movable mirror 67 fixed mirror 68 fixed mirror 69 movable mirror 91 half mirror 92, 93 Shutter 94 Integrator lens

Claims (7)

A light source that emits light, a projection lens that projects a light pattern toward a measurement object, and any of a plurality of branched light paths of light emitted from the light source between the light source and the projection lens With an optical path branching / switching optical system for switching to the optical path,
One of the optical paths is such that a light pattern that passes through the optical path and is projected from the projection lens becomes light with a uniform illuminance distribution,
A pattern generating element for generating a striped optical pattern is provided in another optical path of the optical paths, and the striped optical pattern is projected from the projection lens. Floodlight device. The optical path branching / switching optical system includes a movable mirror that is movable and can switch an optical path through which incident light passes to one of two optical paths, and one of the light that has passed through each optical path. A transflective element that transmits part and reflects part thereof,
Of the light that has passed through one of the optical paths, the light that has passed through the semi-transmissive and semi-reflective element and the light that has passed through the other optical path and has been reflected by the semi-transmissive and semi-reflective element pass through the projection lens. The three-dimensional shape measuring light projecting device according to claim 1, characterized in that it is configured as described above.   The optical path branching / switching optical system passes through one optical path and a first movable mirror that is movable and can switch an optical path through which incident light passes to one of two optical paths. The tertiary according to claim 1, further comprising a second movable mirror for making the light incident on the projection lens so that the direction of the light and the direction of the light passing through the other optical path are the same. Light source for original shape measurement.   The three-dimensional shape measurement light projecting device according to claim 2, wherein the optical path branching / switching optical system includes a fixed mirror for bending the optical path.   The movable mirror switches the optical path by being inserted or removed from the light path from the light source, and is switched to an optical path that does not pass through the pattern generating element when the movable mirror is inserted into the optical path. The three-dimensional shape measurement light projecting device according to claim 2, wherein when the movable mirror is removed from the optical path, the movable mirror is switched to an optical path that passes through the pattern element. The first movable mirror switches an optical path by being inserted into or removed from the optical path from the light source, and does not pass through the pattern generation element when the first movable mirror is inserted into the optical path. Switched to an optical path and switched to an optical path through the pattern element when the first movable mirror is removed from the optical path;
The second movable mirror switches an optical path by being inserted into or removed from the optical path from the pattern generation element toward the projection lens, and when the second movable mirror is inserted into the optical path, Light that has passed through an optical path that does not pass through the pattern generation element is directed to the projection lens, and light that has passed through the pattern element when the second movable mirror is removed from the optical path is directed to the projection lens. The three-dimensional shape measuring light projecting device according to claim 3, wherein the light projecting device is provided. Three-dimensional shape measurement that measures the three-dimensional shape of a measurement object by comparing and analyzing a light pattern whose illuminance periodically changes according to the position and a light pattern with uniform illuminance projected onto the measurement object A device,
The light projecting device according to claim 1;
A line sensor for reading the two light patterns projected onto the measurement object as an image;
A three-dimensional shape measurement apparatus comprising: an image analysis unit that calculates height information of a measurement object based on images of the both light patterns read by the line sensor.

Images