JP2535735B2 - Non-contact type position signal automatic generation method for three-dimensional coordinate detection - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention is a non-contact type in which three-dimensional coordinates representing the shape and size of an object are optically measured in a non-contact manner by a distance-measuring position movement of a pair of microscopes. The present invention relates to a three-dimensional coordinate detection method, in particular, an optical system of a microscope which is downsized and improved so that a position signal of a measurement result is automatically generated.

(Prior Art) A three-dimensional coordinate measuring device is usually used for measuring the shape and dimension of an object having a three-dimensional curved surface of a minute part or an easily deformable object.
That is, as the filler, conventionally, a contact-type filler in which microspheres are attached to the tip of the filler has been used. However, if you try to measure the contour of a three-dimensional curved surface by touching the feeler with an object, it is necessary to correct the influence of the size of the sphere on the measurement result, so not only precise measurement is difficult but also the lead for IC. With a soft and minute object such as a frame, there is a risk of deformation due to the contact of the filler, and accurate shape measurement cannot be expected, so the development of a new non-contact type filler has been desired.

Therefore, one of the inventors of the present invention is an apparatus for performing optically non-contact three-dimensional coordinate detection by combining a pair of microscopes and a pair of television cameras, which perform a distance-measuring position movement by intersecting optical axes with each other. Was developed and disclosed by Japanese Patent Application Laid-Open No. 59-171806.

(Problems to be solved by the invention) However, the feeler of this non-contact type three-dimensional coordinate detection device is quite large, and the weight is about 2.5 kg, which is not easy to handle, and it is troublesome to read the coordinates visually by the scale. However, there was a practical inconvenience.

(Means for Solving Problems) An object of the present invention is to solve the above-mentioned conventional problems, downsize the non-contact feeler to facilitate handling, and automatically generate a position signal representing three-dimensional coordinates. Therefore, it is intended to provide a non-contact type three-dimensional coordinate detection device which facilitates coordinate reading and is suitable for practical use.

That is, the non-contact type three-dimensional coordinate detection device according to the present invention improves the optical system of a pair of microscopes that perform distance-measuring position movement, and configures a television camera using a CCD image pickup device to form a non-contact filler. The size of the object is further reduced, and the image sensor output signal of the television camera is digitized to automatically generate the position signal to automatically move the position of the filler, and the three-dimensional coordinates can be automatically read and recorded. Z perpendicular to the mounting surface with respect to a frame provided so as to be movable in the directions of X-axis and Y-axis parallel to the mounting surface of the table on which
A pair of microscopes each having a support shaft movably in the axial direction and having optical axes that are symmetrically spaced from each other in the direction of the X-axis or the Y-axis with respect to the Z-axis and are inclined at equal angles. An optical system is attached to the support shaft, a pair of television cameras is coupled to the pair of microscopic optical systems, respectively, and an output image taken at a predetermined portion of the subject by the pair of television cameras is synchronously displayed on the same television monitor. A non-contact device for detecting three-dimensional coordinates of the X-axis, the Y-axis, and the Z-axis of the predetermined portion of the subject based on the amount of movement of the frame and the support shaft when they are matched with each other. A first deflecting optical element for advancing the light beam introduced through the optical axis along the optical axis, and transmitting and transmitting the light beam from the first deflecting optical element. A second deflecting optical element for advancing a light beam reflected by the subject in a direction intersecting the optical axis and a reflected light beam traveling from the second deflecting optical element in a direction intersecting the optical axis are limited. The microscopic optical system is configured using a third deflecting optical element that is reflected by a plurality of reflections in the same space and is incident on the image pickup surface of the television camera, and the image pickup outputs of the pair of television cameras are provided. The frame and the support shaft are respectively driven and moved to the positions where the mutual correlations obtained by binarizing the image in the vicinity of the predetermined portion of the subject and binarizing the images are moved, and X, It is characterized in that electric signals respectively representing Y, Z triaxial coordinate values are generated by respective driving means.

(Operation) Therefore, according to the present invention, the practicality of the non-contact type three-dimensional coordinate detecting device using the distance-measuring position movement of the pair of microscopes is remarkably improved, and this kind of three-dimensional coordinate detecting device is required. For example, it is extremely useful for press die compounders, IC lead frame manufacturers, and the like.

(Example) Hereinafter, the present invention will be described in detail with reference to the drawings.

First, a first example of a schematic configuration of the entire non-contact type three-dimensional coordinate detecting device including a three-dimensional coordinate measuring machine equipped with a non-contact filler and an accessory for processing measurement data according to the present invention will be described.
Shown in the figure. The schematic configuration shown in the figure is almost the same as the conventional device disclosed in the above-mentioned publication, and is combined on both side rails of the bridge type fixed base 1 so as to be movable in the X-axis direction parallel to the subject mounting table 4. The horizontal / vertical frame 2 is installed movably in the Y-axis direction, the support shaft 3 movable in the vertical Z-axis direction is attached to the table 4, and the support shaft 3 is expanded to the lower end of the support shaft 3. The illustrated filler portion is attached. That is, with respect to the Z-axis direction formed by the support shaft 3, for example, a pair of microscope optical systems 5, which are symmetrically separated from each other in the X-axis direction and inclined at the same angle, for example, 45 °, and whose optical axes intersect with each other on the Z-axis. 6 is attached, and a pair of CCD camera heads 7 and 8 are combined with the pair of microscope optical systems 5 and 6, respectively. A light beam from a light source 9 separated from the subject is introduced into the microscope optical systems 5 and 6 through a pair of optical fibers 10 and 11, respectively, to illuminate the subject, and an optical image of the subject by a reflected light flux from the subject. To form an image on the image pickup surface of the CCD cameras 7 and 8 and guide the image pickup output image signal to the image processing device 15 through the camera controllers 12 and 13 under the control of the synchronization signal generator 14 and process it. The resulting double image is displayed on the television monitor 16.

The output image of the subject captured by the CCD cameras 7 and 8 is generally a double image on the screen of the monitor 16, but the crossing point on the Z axis of the optical axes of the pair of microscopes 5 and 6 is moved up and down by moving the support shaft 3. Then, when the intersection coincides with a predetermined portion of the subject, the double images coincide with each other to form a single image, so that the Z-axis coordinate of the predetermined portion of the subject can be measured by such an operation. Regarding both the X-axis and Y-axis coordinates, a cross line indicating the intersection of the optical axes of the microscope on the Z-axis is superimposed and displayed on the screen of the monitor 16, and the cross point of the cross line and the measurement point of the subject match. Move the frame 2 like this, and
Both X and Y axis coordinates can be detected.

The reading of each X, Y, Z coordinate value is performed by reading the amount of rotation of each gear system that drives and moves the frame 2 and the support shaft 3 as a digital signal by, for example, an absolute encoder, and is shown in FIG. As described above, the stop switch 18 is used to stop the digital coordinate signal that changes momentarily according to the movement of the frame 2 and the support shaft 3 when the cross line intersection point on the screen of the monitor 16 coincides with the object measurement point. The data is displayed on the coordinate display unit 17, processed by, for example, the desktop computer 19, and recorded on the plotter 20.

In the present invention, in order to reduce the size and weight of the optical non-contact filler used as described above in an enlarged manner in FIG. It is configured as shown in the figure. In the illustrated optical system, the luminous flux from the light source 21 that is separated while avoiding the measurement accuracy deterioration due to the deformation of the optical system due to the generation of heat is made incident on the right-angle prism 25 through the optical fiber, and is incident on the optical axes of the microscopes 5 and 6. Deflect along. The subject 25 is illuminated by the incident light flux that has passed through the beam splitter 23 and travels straight along the optical axis, and the reflected light flux from the measurement point of the subject 25 is measured by a CCD camera.
When guiding to the image pickup device 27 of 7, 8, even if the whole non-contact feeler is configured compactly, the working distance of the optical system in the microscope 5, 6, that is, the distance between the non-specimen 25 and the objective lens 24 should be sufficiently long. In order to allow a measurable height for the subject, the focal length of the lens system is set to be sufficiently long so that the optical path length between the objective lens 24 and the image sensor 27 on which the non-analyte optical image is formed is sufficiently long. As a means for setting, the reflected light flux along the optical axis of the microscope 5, 6 is intersected with the optical axis by the beam splitter 23, is preferably deflected in a direction orthogonal to the optical axis, and further is folded back by the Porro prism 26 to the image pickup element 27. The optical system is configured to make the light incident. In order to reduce the size of the non-contact feeler, only the image pickup device 27 of the CCD cameras 7 and 8 is separately mounted in the feeler main body, and the drive control circuit system is installed outside the feeler main body. As a result of such a configuration, each size and weight of the non-contact feeler main body according to the present invention are about half that of the conventional one. That is, the weight of the non-contact feeler body was about 800 grams, and the outline dimensions were as shown in FIG.

Therefore, in the optical non-contact type three-dimensional coordinate detection device developed by the present inventors, the Z-axis coordinate of the measurement point of the object is detected by matching the double images by the pair of microscopes. Conventionally, the matching was performed visually, so not only the measurement took time, but also the measurement error was large. Therefore, in the present invention, the coincidence detection of the double images is automatically performed by the image processing device having the structure shown in FIG. 4, for example. In the illustrated configuration, the left and right imaging output signals of a pair of CCD cameras combined with a pair of microscopic optical systems are binarized through a screen cutout circuit 28 into a binarization circuit 29.
To the correlation circuit 30, and then to the correlation circuit 30 to obtain the maximum point of the cross-correlation by digital processing of the left and right image signals and obtain the maximum value of the cross-correlation. The Z-axis coordinate detection of the sample measurement point is automatically performed in real time. That is, the output correlation value of the correlation circuit 30 is led to the integral counting circuit 31, and the change of the correlation value due to the movement of the feeler in the Z-axis direction is counted under the control of the 10 MHz clock generation circuit 32, and the counting result is obtained. Matching degree display device 33
To be displayed. In addition, in the illustrated image processing apparatus,
The logical product of the digital image signal representing the vicinity of the object measurement point from the binarization circuit 29 and the crosshair signal from the crosshair generation circuit 34 that has supplied both vertical and horizontal synchronization signals is taken out from the AND circuit 35 and displayed as an LED. Guide to the device 36, display the match / mismatch between the subject measurement point and the center point of the crosshair as described below,
Both X-axis and Y-axis coordinates can be detected.

Therefore, each optical axis of the pair of microscopes in the present invention is Z
Since it is oblique to the axis, it is often not perpendicular to the measurement surface of the subject, for example, a flat plate. Therefore, the microscopic optical system is focused only in the area near the measurement point. For example, as shown in FIG. 5, three point images of the same size that are equally spaced across the center of the measurement surface are displayed on the monitor.
It is not displayed on the 16 screen as it is on the measurement surface. Therefore, it is necessary to limit the image pickup area only in the vicinity of the center where the image is in focus and to provide a window for cutting out the screen so as to correlate the left and right image pickup output image signals, and the screen cutout circuit in the image processing apparatus shown in FIG. 28 is provided for that purpose.

The above-described screen cutout state is shown in FIG. 6 (A), and an example of the detailed configuration of the screen cutout circuit 28 is shown in FIG. 6 (B).
That is, as shown in FIG. 6A, in the vertical scanning of the screen, the section from the upper end to the scanning line at time t _{1 to} the scanning line at time t ₂ and the time t ₃ from the left end to time t ₄ As shown in FIG. 6 (B), assuming that only the central area surrounded by the section up to the point is cut out, the vertical synchronizing signal is delayed by time t ₁ and time t ₂ respectively and horizontal and horizontal. Sync signal at time t ₃ and
The delayed output from the multivibrators 39 and 40, which delays by t _4, is led to the AND circuit 41, and the on / off switch 42 is driven by the AND output, and only the image signal corresponding to the central region of the screen is cut out and taken out. It is preferable that the peripheral images outside the central region are simultaneously displayed with reduced contrast in order to easily find the measurement point of the subject.

On the other hand, the X-axis and Y-axis position coordinate detection is performed by the crosshair generation circuit as described above with respect to the image processing apparatus shown in FIG.
The crosshair signal from 34 is projected on the screen of the monitor 16, and the match between the intersection of the crosshair and the measurement point of the subject is conventionally detected visually, but in the present invention, the image processing apparatus For example, an X-axis / Y-axis coordinate detection circuit having a structure as shown in FIG. 7B is provided in the LED display device 36 having the structure shown in FIG. That is, as shown in the upper part of FIG. 7 (A), for example, a binarized captured output image of the right camera 7 displayed at the position of the reference point formed by the intersection of the crosshairs displayed in the center of the screen of the monitor 16. If the signal is at H level, that is, white level, the lower G _L (green) LED, that is, the light emitting diode is turned on as shown in the lower stage (a), and if at L level, that is, the black level, the lower stage (c).
The right G _L · (green) LED, that is, the light emitting diode is lit as shown in, and if it is L level, that is, the black level, the right G _R · LED is lit as shown in the lower row (c), and the position of the reference point When the binarized image signal rises or falls at, the central R (red) LED is turned on as shown in the lower part (b), and the X-axis
The Y-axis coordinate detection circuit is configured, and each of the detection output signals
The LEDs are turned on and the frame 2 is appropriately driven and moved so that both X-axis and Y-axis coordinates can be automatically detected. An example of the configuration of such an X-axis / Y-axis coordinate detection circuit is shown in FIG. In the configuration shown in the figure, the vertical line signal and the horizontal line signal of the cross line are guided to the AND circuit 46, and the cross line intersection signal which is the logical product thereof is supplied to the AND circuits 43 and 45, and the right camera binarization described above is performed. Gate the image output signal and its inverted signal by the inverter 44,
The monostable multivibrators 47 and 48 are driven by the respective gate output signals obtained when the binarized image signal is at the H level and the L level, and FIG.
Therefore, the signals respectively representing the states of (a) and (c) of FIG. 1 are formed, and the corresponding G-LEDs 50, 52, 50, 52 are turned on by the signals.

Furthermore, when the boundary portion between the H level and the L level of the binarized image signal coincides with the intersection of the cross lines and becomes the state of FIG. 7B, the signal level is near the threshold level of the binarized image signal. Becomes unstable and the AND circuits 43 and 45 become unstable and alternate to the logic 1 state. Therefore, the width of the output pulse of the monostable multivibrators 47 and 48 is made slightly wider than the frame period of the television image signal. However, if you set it to 1/30 seconds or more, for example, monostable multivibrators 47 and 48
And the output signals of and become logic 1 at the same time, and the gate output signal of the AND circuit 49 that guides these signals represents the matching state between the reference point and the object measurement point shown in FIG.
Turn on LED51.

The result of measuring the repeatability of the coordinate detection by the three-dimensional coordinate detecting apparatus of the present invention configured and operated as described above for each axis individually is represented by the standard deviation of the X, Y, Z axis coordinates, and σ _x
= 0.4 μm, σ _y = 0.0 μm, σ _z = 0.6 μm.

Also, the triaxial coordinates in a state where the width of the binarized threshold value of the imaging output image signal is finely changed as shown in FIG. Repeatability of simultaneous automatic detection is standard deviation σ _x = 1.1μ
m, σ _y = 0.6 μm, σ _z = 1.4 μm, and standard deviation σ _x = 1.2 μm, σ _y = 0.9 μm, σ in the same visual measurement.
Repeatability higher than _z = 1.4 μm was obtained.

Further, FIG. 10 (A) shows the result of the coordinate measurement showing the lead interval in the Y-axis direction in the lead frame for IC as shown in FIG. 9, and for comparison, the same result is obtained by the conventional universal projector. The measurement result of is shown in FIG. 10 (B). In addition,
IC to measure the same point on each measuring device
It is extremely difficult to mount the lead frame for use in the non-contact feeler of the present invention, although the measurement results of both are not the same for the same subject. Has a standard deviation of 0.3 μm, which is higher than that of the universal projector with a standard deviation of 0.5 μm.

Further, in the IC lead frame as shown in FIG. 11, FIG. 12 shows the measurement result of the Z-axis coordinate representing the depth from the upper surface of the frame which is the reference surface of the pad surface for mounting the IC chip. In this measurement, X'Y 'of the reference plane
A three-dimensional coordinate measuring program for converting the Z ′ axis coordinate system into the XYZ axis coordinate system of the pad surface to be measured was used. Therefore, if the coordinate values of the points P _i on the pad surface are input after the coordinate values of the three points C _{1 to} C ₃ on the upper surface of the frame are input, the coordinate values of the coordinate-converted points P _i are obtained. The Z-axis coordinate value indicates the pad surface depth. FIG. 12 shows the result of repeating such measurement three times, and the repeatability thereof was standard deviation σ _z ′ = 2.7 μm. It should be noted that the repeatability when simply measuring the pad surface depth from the top surface of the frame 20 times is a standard deviation of 0.6 μm.
_{It is considered that z} ′ is deteriorated due to the shape deviation of the frame outer frame surface.

(Effects of the Invention) As is clear from the above description, by using the optical non-contact filler according to the present invention, it is possible to study a lead frame for an IC and a plastic working which cannot be measured by the conventional contact-type filler and are easily deformed. It is possible to automatically and easily detect the three-dimensional coordinates of the grid line or the like on the three-dimensional object for use with high precision. That is,
According to the present invention, the non-contact filler is significantly smaller and lighter than the conventional one, and the coordinate detection output signal is automatically obtained. Therefore, the accuracy of three-dimensional coordinate detection is improved, and the repeatability is represented by the standard deviation. 0.4 for a reference sphere with a diameter of 0.5 mm
~ 1.1 μm, and 2.5 μm for IC lead frame
The degree of accuracy can be easily and reliably obtained.

[Brief description of drawings]

FIG. 1 is a structural layout view showing an example of a schematic structure of a non-contact type three-dimensional coordinate detecting device according to the present invention, and FIG. 2 is a perspective view schematically showing a structural example of a microscopic optical system in the non-contact filler. FIG. 3 is a front view showing an example of schematic dimensions of the non-contact filler, and FIG. 4 is a block diagram showing an example of a circuit configuration of an image pickup output image processing device in the three-dimensional coordinate detecting device, and FIG. Is also a diagram schematically showing an example of a mode of imaging an object of a microscopic optical system in the non-contact filler, and FIGS. 6 (A) and 6 (B) are also mode of screen cutout and screen cutout in the image processing apparatus. A diagram and a block diagram respectively showing an example of the circuit configuration are shown in FIGS. 7A and 7B, which show a mode of X-axis / Y-axis coordinate detection by the optical non-contact filler and an X-axis Y-axis coordinate detection circuit. Structure FIG. 8 is a diagram showing a mode of binarization of the imaged output image signal, and FIG. 9 is a diagram showing a mode of Y-axis coordinate detection experiment of the IC lead frame. A diagram showing an example, FIGS. 10 (A) and 10 (B) are also characteristic curve diagrams showing an example of the measurement result of the Y-axis coordinate of the lead frame for the IC and a conventional measurement result, respectively, and FIG. 11 is the same IC. FIG. 12 is a characteristic curve diagram showing an example of the measurement result of the Z-axis coordinate of the lead frame for the IC, which is an example of an embodiment of the Z-axis coordinate detection experiment of the lead frame for IC. 1 …… Bridge type fixed base 2 …… Vertical / horizontal frame 3 …… Support shaft 4 …… Table for placing specimen 5,6 …… Microscope optical system 7,8 …… CCD camera / head 9 …… Illumination Light source, 10,11 ...... Optical fiber 12,13 ...... Camera controller, 14 ...... Synchronization signal generator 15 ...... Image processing device, 16 ...... Television monitor 17 ...... Coordinate display unit, 18 ...... Stop Switch 19 …… Desktop computer 20 …… Plotter, 21 …… Illumination light source 22 …… Right angle prism, 23 …… Beam splitter 24 …… Objective lens, 25 …… Subject 26 …… Porro prism, 27 …… Image sensor 28 …… Screen cut-out circuit, 29 …… Binarization circuit 30 …… Correlation circuit, 31 …… Integration (counting) circuit 32 …… Clock generation circuit, 33 …… Match degree display device 34 …… Cross line generation circuit, 35 …… AND circuit 36 …… LED display 37,38,39,40,47,48 …… Monostable multivibrator 41,43,4 5,46,49 …… AND circuit 42 …… ON / OFF switch 44 …… Inverter 50,51,52 …… LED

Claims (2)

(57) [Claims] 1. A frame, which is provided so as to be movable in directions of an X axis and a Y axis parallel to a mounting surface of a table on which a subject is mounted, moves in a direction of a Z axis perpendicular to the mounting surface. A support shaft is attached so as to be possible, and a pair of microscopic optical systems are provided which are symmetrical with respect to the Z axis and are separated from each other in the direction of the X axis or the Y axis and have optical axes inclined at equal angles. Mounted on a shaft, coupled with a pair of television cameras to the pair of microscopic optical systems,
The captured output image of a predetermined portion of the subject by the pair of television cameras is synchronously displayed on the same television monitor, and the frame and the supporting shaft are moved by the moving amount when they are matched with each other. In a method for non-contact detection of three-dimensional coordinates with respect to the X axis, the Y axis, and the Z axis, the output images captured by the pair of television cameras are localized in the vicinity of the predetermined portion of the non-specimen and then binarized. The frame and the support shaft are respectively driven and moved to a position where the mutual correlation obtained by the above is maximized, and electric signals respectively representing the X, Y and Z triaxial coordinate values of the position are respectively driven by respective driving means. A method for automatically generating a position signal for non-contact type three-dimensional coordinate detection, which is characterized by being generated. 2. A cross representing the binarized image pickup output image signal, an inversion signal of the binarized image pickup output image signal, and a position on the display screen of the television monitor where the predetermined portion of the subject should be displayed. The non-contact type three-dimensional coordinate detecting device according to claim 1, wherein the frame is driven in accordance with a logical product of each of the line signals and moved in the directions of the X-axis and the Y-axis. Position signal automatic generation method.