JP2004257940A - Location detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a location detector capable of detecting height of an object to be measured in wide measuring range and with a high resolution using a simple constitution. <P>SOLUTION: A slit plate having a plurality of slits is provided so that the normal of the slit plate is inclined to an optical axis from a light source to the object to be measured, and the light emitted from the light source is cast onto the slit by an illumination lens. An imaging optical system focuses each image of a plurality of slits irradiated with the light from the light source, on different positions on a straight line which is perpendicular to the reflection surface of the incidence light of the object to be measured and passing the object to be measured. The image of the slits is photographed with a camera, a slit image which is most sharp is selected, and the height of the object to be measured is measured from the location of display of the slit image indicated on the display. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a position detection device that makes light incident on an object and detects the position of the object from a change in a reflection position at which the incident light is reflected.
[0002]
[Prior art]
Conventionally, light emitted from a light source is incident on a measurement target through a slit, and an optical height for detecting the height of the measurement target from a position where the incident light is reflected on the measurement target. Detection devices are known.
[0003]
For example, an apparatus disclosed in Japanese Patent Application Laid-Open No. 7-332929 forms an image of a slit on a measurement object, and further forms the image on a photoelectric conversion element to detect the height of the measurement object. Was something.
[0004]
[Patent Document 1]
JP-A-7-332929
[Problems to be solved by the invention]
In such a conventional apparatus, when the height of the measurement target is a predetermined height, the image of the slit is formed on the measurement target, and a clear image can be obtained. However, when the height of the object to be measured is shifted from the above-described predetermined height, the image of the slit gradually becomes an unclear image as it shifts, so-called blurred image, and the height of the object to be measured is reduced. Did not get clear. For this reason, the conventional apparatus has a disadvantage that the range of the measurable height must be extremely narrow.
[0006]
The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a position detection device that can detect the height of a measurement target with a simple configuration, in a wide measurement range, and with high resolution. To provide.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the position detecting device according to the present invention is configured such that a perpendicular line of a slit plate having a plurality of slits is inclined with respect to an optical axis from a light source to an object to be measured. Is provided.
[0008]
More specifically, the present invention provides the following position detecting device.
[0009]
(1) A position detection device that irradiates a target object with light emitted from a light source via a slit plate and detects a position of the target object from a change in a reflection position at which the incident light is reflected on the target object. And
In the slit plate, a plurality of slits through which light from the light source can pass, and,
An angle formed by a vertical line perpendicular to the plate surface of the slit plate and an optical axis from the light source to the target object is larger than 0 degree and smaller than 90 degrees. Detection device.
[0010]
(2) An imaging optical system is positioned on the optical axis between the slit plate and the object, and
The imaging optical system forms an image of each of the plurality of slits at a different position on a straight line passing through the object perpendicular to the reflection surface of the incident light on the object. (1) The position detecting device according to (1).
[0011]
In the above-described invention (1), the angle between the perpendicular to the plate surface of the slit plate and the optical axis from the light source to the object is greater than 0 degrees and smaller than 90 degrees. In the invention of the above (2), the images of the plurality of slits are formed at different positions on a straight line passing through the target object perpendicularly to the reflection surface of the incident light on the target object. did. According to the invention of (1) or (2), even when the height of the object is changed, any one of the plurality of slits can be imaged on the object. The height of the object can be accurately obtained with a simple configuration.
[0012]
In this specification, the term “slit” means an opening having a smaller width than a length, a narrow gap or a narrow gap for limiting the width of a light beam or a particle beam. Further, the “imaging optical system” means an optical system that forms an image on a slit, and for example, there is an optical system that uses a lens. The number of optical elements such as lenses is not limited, and may be any element that adjusts the direction of light passing through the slit and forms an image.
[0013]
(3) The position detecting device according to (1), wherein each of the plurality of slits has a longitudinal direction oriented in one predetermined direction, and the positions of the plurality of slits are different in the one direction.
[0014]
According to the above-described invention (3), since the longitudinal direction of each of the plurality of slits is oriented in one predetermined direction and the positions of the plurality of slits are different in one direction, a large number of slits are formed in the slit plate. Can be formed, and images of each of the multiple slits can be clearly formed, so that the resolution of position detection can be increased.
[0015]
In the present specification, the “position of the plurality of slits” may be the position of the center of gravity of the slit, the position of an end such as a predetermined corner, or any position that can be specified from the geometrical shape of the slit.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0017]
FIG. 1 shows a position detecting device 10 according to an embodiment of the present invention. FIG. 1 is a diagram when the position detection device 10 is viewed from the side.
[0018]
A stage 12 that can move in the vertical direction is provided substantially below the center of the position detecting device 10 as indicated by the white arrow shown in FIG. The stage 12 incorporates an electric motor (not shown), and by controlling the driving of the electric motor, the stage 12 can be moved up and down. On the upper surface of the stage 12, an object to be measured 14, for example, a substrate for printed wiring or a silicon substrate is mounted.
[0019]
A light source 16, for example, a light-emitting diode is provided on a support member (not shown) diagonally above the stage 12, that is, in the example shown in FIG. The positioning and the direction of the light source 16 are adjusted so as to irradiate the measurement object 14 with light.
[0020]
An illumination lens 18 is provided on a support member (not shown) in front of the traveling direction of light emitted from the light source 16 (hereinafter, referred to as front). The illumination lens 18 is positioned so that its center is located on the optical axis A1 of the light emitted from the light source 16. The surface including the diameter of the illumination lens 18 is adjusted so as to be perpendicular to the optical axis A1.
[0021]
A slit plate 20 is provided on a support member (not shown) in front of the illumination lens 18. As shown in FIG. 2 described later, a plurality of through holes, for example, three through holes are formed in the slit plate 20 in the direction perpendicular to the slit plate surface 22 as a plurality of slits. The slit plate surface 22 is a surface that spreads in the direction in which the slit plate 20 extends. Here, “extend” means that the object is present in a range defining the object without changing the size of the object itself.
[0022]
The slit plate 20 is positioned on a support member (not shown) such that the slit plate surface 22 is inclined with respect to the optical axis A1. For example, in the example shown in FIG. 1, the vertical line n of the slit plate surface 22 of the slit plate 20 is positioned so as to be inclined by an angle θ with respect to the optical axis A1. The direction of the inclination of the perpendicular line n is preferably a downward direction D. Further, it is more preferable that the angle θ of the inclination of the perpendicular line n is larger than 0 degree and smaller than 90 degrees. Furthermore, as will be described later, images of the plurality of slits are formed at different positions on a straight line L that is perpendicular to the reflection surface of the incident light on the measurement object 14 and passes through the measurement object 14. As described above, it is more preferable that the slit plate 20 is provided so as to be aligned.
[0023]
An imaging lens 24 is provided on a support member (not shown) in front of the slit plate 20. The imaging lens 24 is positioned such that its center is located on the optical axis A1 and an image of a slit (not shown) formed in the slit plate 20 can be formed on the upper surface of the measurement object 14. Have been. The plane P2 including the diameter of the imaging lens 24 is adjusted so as to be perpendicular to the optical axis A1.
[0024]
With the above configuration and arrangement, the light emitted from the light source 16 is incident on the illumination lens 18, and the light incident on the illumination lens 18 is spread by the illumination lens 18 and applied to the slit plate 20. Only the light that reaches the slit formed in the slit plate 20 out of the irradiated light passes through the slit.
[0025]
The light that has passed through the slit has its traveling direction adjusted by the imaging lens 24 and is irradiated on the measurement object 14. Thereby, any one of a plurality of slits (not shown) formed in the slit plate 20 can be formed on the upper surface of the measurement target 14.
[0026]
Further, the conditions of the position and the orientation of the slit plate 20 and the imaging lens 24 are not limited to those described above, and the images of the plurality of slits are perpendicular to the reflecting surface of the measurement object 14 of the incident light. Further, it is more preferable that the slit plate 20 and the imaging lens 24 are provided so as to form an image at different positions on the straight line L passing through the measurement object 14.
[0027]
An imaging lens 26 is provided on a support member (not shown) diagonally above the stage 12, in the example shown in FIG. 1, above the left side of the stage 12. The imaging lens 26 is adjusted so that its center is located on the optical axis A2 and a plane including the diameter of the imaging lens 26 is perpendicular to the optical axis A2.
[0028]
A CCD camera 28 is provided on a support member (not shown) in front of the light traveling direction of the imaging lens 26. The above-described imaging lens 26 is positioned by the CCD camera 28 so that the upper surface of the measurement object 14 forms an image. The focus and magnification of the CCD camera 28 are adjusted in advance so that the entire surface of the upper surface of the measurement object 14 or a predetermined range can be photographed. The CCD camera 28 is oriented and positioned so that the center of the upper surface of the measuring object 14 is projected substantially at the center of the display unit of the display device 29 connected to the CCD camera 28.
[0029]
FIG. 2 schematically shows the slit plate 20 described above.
[0030]
The slit plate 20 has a flat and circular shape, and is formed of a material that does not allow light emitted from the light source 16 to pass therethrough, for example, chrome. The slit plate 20 has three slits 30, 32 and 34 formed therein. The three slits 30, 32, and 34 are through holes having long rectangular openings. Each of the three slits 30, 32, and 34 is formed so that the longitudinal direction thereof is oriented in one predetermined direction, that is, in the example shown in FIG. Further, the three slits 30, 32 and 34 are arranged such that the positions in the longitudinal direction are all different. In the example shown in FIG. 2, the slit 32 is disposed substantially at the center of the slit plate 20, the slit 30 is disposed on the upper right with respect to the slit 32, and the slit 34 is disposed on the lower left with respect to the slit 32. Have been.
[0031]
In addition, in the example shown in FIG. 2, the case where the number of slits is three is shown, but more slits may be formed. Further, although the shape of the slit is made long, any other shape may be used, as long as the feature of the shape can be specified from the geometrical shape of the slit. Furthermore, although the positions of the three slits 30, 32 and 34 are all different in the longitudinal direction, they may be formed so as to be at the same position in the longitudinal direction.
[0032]
When the slit plate 20 is provided in the position detecting device 10 shown in FIG. 1, the slit plate 20 is arranged so that the direction perpendicular to the longitudinal direction of the slit is directed to the straight line L shown in FIG. For example, in the case of the slit plate 20 shown in FIG. 2, the slit plate 20 is arranged such that the upper direction of the slit plate 20 (the direction of the arrow Y shown in FIG. 2) faces the straight line L.
[0033]
FIG. 3 shows how the images of the three slits 30, 32, and 34 are formed on the upper surface of the measurement target 14 when the slit plate 20 is arranged as described above. FIG. 3 is an enlarged view of the slit plate 20, the imaging lens 24, and the measurement object 14 shown in FIG.
[0034]
The light that has passed through the slit 32 formed substantially at the center of the slit plate 20 travels along the optical axis A1. In this case, as shown in the lower left of FIG. 3, when the upper surface of the measuring object 14 is located at the height of z1, the image of the slit 32 is formed on the upper surface. At this time, the remaining images of the slits 30 and 34 do not form an image on the upper surface of the measurement target 14. When this state is photographed by the CCD camera 28, an image as shown in FIG. 4A is obtained. 4A to 4C show images displayed on a display device 29 connected to the CCD camera 28 when the upper surface of the measurement object 14 is photographed by the CCD camera 28. The solid square lines outside of (a) to (c) are lines indicating the outline of the display unit of the display device 29. 4A to 4C is a line indicating the center position of the display unit in the left-right direction. When the upper surface of the measuring object 14 is photographed by the CCD camera 28, the image is inverted by the imaging lens 26, so that the left and right relationship is reversed.
[0035]
When the upper surface of the measurement object 14 is located at the height of z1, the image of the slit 32 is located at the center in the left-right direction of the display unit of the display device 29, has a clear image, and has the remaining slits 30 and The image 34 is an image whose outline is unclear, and is a so-called blurred image.
[0036]
The light passing through the slit 30 travels along the line A1 '. In this case, as shown in FIG. 3, when the upper surface of the measurement object 14 is located at the height of z2, an image of the slit 30 is formed on the upper surface. When this state is photographed by the CCD camera 28, an image as shown in FIG. 4B is obtained. That is, the image of the slit 30 is located at the center in the left-right direction of the display unit and has a clear contour, and the images of the remaining slits 32 and 34 have an indistinct contour.
[0037]
Further, the light passing through the slit 34 travels along the line A1 ″. In this case, as shown in FIG. 3, when the upper surface of the measurement target 14 is located at the height of z3, the upper surface 4 (c) is obtained by photographing this state with the CCD camera 28. That is, the image of the slit 34 is located at the center in the left-right direction, The image has a sharp outline, and the images of the remaining slits 30 and 32 have an indistinct outline.
[0038]
With the above-described configuration, when an image of any one of the three slits is captured as a clear image, the position of the upper surface of the measurement target 14 in the height direction z can be determined. Thereby, the relationship between the state of the captured image of the slit and the position of the upper surface of the measurement target 14 in the height direction z can be obtained.
[0039]
Further, even when none of the captured images of the slit is clear, the measurement target is determined from the positional relationship in the height direction z of the upper surface of the measurement target 14 when the image of the slit is captured as a clear image. The height position of the upper surface of the object 14 can be obtained. That is, when an image of any one of the three slits is captured as a clear image, the image of the slit is always centered in the left-right direction of the display unit of the display device 29 as described above. Is displayed. On the other hand, when the image of the slit is captured as an unclear image, the image of the slit is displayed at a position other than the center in the left-right direction of the display unit. When the stage 12 is moved downward with the state shown in FIG. 4A as the reference position in the height direction z of the upper surface of the measurement object 14, the images of the three slits gradually move to the right on the display unit. When the stage 12 is moved upward, the images of the three slits gradually move leftward on the display unit.
[0040]
Thus, by measuring the position of the slit image displayed on the display unit of the display device 29 on the display unit, the position of the upper surface of the measurement target 14 in the height direction z can be calculated. Specifically, as shown in FIG. 5, a photographed image that is the most clear image, for example, an image of the slit 32 is selected, and the image from the left end of the display unit to the image of the slit 32 is selected. By measuring the distance x1 and the distance x2 from the center of the display unit to the image of the slit 32, the distance x1 can be converted into the height direction z of the upper surface of the measurement object 14.
[0041]
In the above-described embodiment, the case where the slit plate 20 is tilted in the downward D direction is shown. However, the slit plate 20 is tilted in the depth direction with respect to the plane of FIG. It may be provided.
In the above-described embodiment, the case where the position in the height direction is detected has been described. However, by setting the optical axes A1 and A2 so as to be included in the horizontal plane, the position in the horizontal direction can be detected.
[0042]
【The invention's effect】
With a simple configuration, it is possible to detect the height of the measurement target in a wide measurement range and with high resolution.
[Brief description of the drawings]
FIG. 1 is a side view schematically showing a position detection device 10 according to an embodiment of the present invention.
FIG. 2 is a front view schematically showing a slit plate 20;
FIG. 3 is a schematic diagram showing a state in which images of three slits 30, 32, and 34 are formed on an upper surface of a measurement target 14;
FIG. 4 is a view showing an image displayed on a display unit of a display device 29 connected to the CCD camera 28 when the upper surface of the measurement object 14 is photographed by the CCD camera 28.
FIG. 5 is a diagram showing images of the slits when all the images of the three slits 30, 32, and 34 are shifted from the center of the display unit of the display device 29.
[Explanation of symbols]
10 Position detection device 14 Measurement object (object)
Reference Signs List 16 light source 20 slit plate 22 slit plate surface 24 imaging lenses 30, 32, 34 slits (plural slits)
A1 Optical axis

Claims (4)

A position detection device that irradiates light emitted from a light source to an object through a slit plate as incident light, and detects a position of the object from a change in a reflection position at which the incident light is reflected on the object. ,
The slit plate is provided with a plurality of slits through which light from the light source can pass, and
An angle formed by a perpendicular line perpendicular to the plate surface of the slit plate and an optical axis from the light source to the target object is greater than 0 degree and smaller than 90 degrees. Detection device. An imaging optical system is positioned on the optical axis between the slit plate and the object, and
The image forming optical system forms an image of each of the plurality of slits at a different position on a straight line passing through the object perpendicular to a reflection surface of the incident light on the object. Item 4. The position detecting device according to Item 1. The position detecting device according to claim 1, wherein a longitudinal direction of each of the plurality of slits is oriented in a predetermined one direction, and positions of the plurality of slits are different in the one direction. The position detection device according to claim 1, wherein the change in the reflection position is a change in a position in a direction perpendicular to the reflection surface.

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