JPH02278111A - Measuring apparatus of position of light point - Google Patents

Abstract

PURPOSE:To enable measurement of the position of a light point relating to the first reflection by intercepting an image light from a light point relating to the second reflection. CONSTITUTION:A light-position detector (PSD) 1 outputs a pair of signals corresponding to a position of a light on a light-sensing surface and the intensity of a sensed light. Next, an image-forming optical means 2 forms an image of a light point on a surface 3 to be inspected, on a light-sensing surface of the PSD 1. A light-intercepting means 4 constructed of a light-intercepting plate and a mechanism for sliding the light- intercepting plate, or of a liquid-crystal shutter, is disposed on the light-sensing surface of the PSD 1 and intercepts a part of an image light. Moreover, a light-interception control means 5 controls the light-intercepting means 4 for intercepting the image light from a virtual light point L'2 outside a prescribed area, adjusting the sphere of interception. Even when an incident light flux is reflected twice on the surface 3 to be inspected and two light points L1 and L2 are formed, the image light from the light point L2 relating to the second reflection, e.g. the virtual light point L'2 located below a point of the lower limit of the surface 3 and not existing actually, is intercepted according to this constitution. On the light-sensing surface of the PSD 1, therefore, only an image of the light point L1 relating to the first reflection is formed.

Description

[Detailed description of the invention] [Summary] This invention relates to a light spot position measuring device that is used in a visual inspection device, etc. and measures the position of a light spot formed by irradiating light onto an inspection surface. In order to be able to measure the position of a light spot, there is provided an optical position detector, an imaging optical means for forming an image of the light spot on the inspection surface on the light receiving surface of the light position detector, and a light spot on the light receiving surface. a light blocking means arranged to block a part of the imaged light; a light blocking control means controlling the light blocking means to adjust the light blocking range in order to block the imaged light from the virtual light point outside the specified range; First with
The invention comprises a first optical position detector, a first imaging optical means for forming an image of a light spot on the inspection surface onto a light receiving body of the first optical position detector, and a second optical position detector; The light spot on the inspection surface is imaged on the light-receiving surface of the second optical position detector, and the light spot by one reflection [ ] behind the light spot is imaged at a specific position on the light-receiving surface. a light shielding member disposed at the specific position on the light-receiving surface of the second optical position detector to block imaging light to the specific position, and the first optical position detector. a light spot position calculation means for calculating a light spot position related to the first reflection by removing a component related to the second reflection included in the output of the second optical position detector using the output of the second optical position detector; , constitutes the second invention.

U Field of Industrial Application] The present invention relates to a light spot position measuring device that is used in a visual inspection device or the like and measures the position of a light spot formed by irradiating light onto an inspection surface.

U Prior Art] FIG. 6 shows a conventional light spot height position measuring device used in an appearance inspection device for a printed wiring board on which chip components are mounted.

The incident light beam is convergently irradiated from directly above the inspection surface 10 (the top surface of the terminal of the chip component in FIG. 6), and the light spot formed on the inspection surface 10-A is detected by the imaging lens I2. vessel(
PSD) l 4 is imaged on the light receiving surface to form a light spot image Sl. From a pair of terminals of PSDI4, due to the photoelectric effect, a current of 1. , l, is retrieved. Current summer, 1. are the voltages v1 and ■! due to the current/mm pressure transformers 16 and 1B, respectively. is converted into and supplied to the arithmetic circuit 2o, and the arithmetic circuit 20t
j: X = (V, -L)/(V, , +-v,)
Calculate. This position This is the position of the light spot image S, of L, and corresponds to the height of the light spot image S, on the inspection surface 10. Inspection surface 1
Height defects are detected by scanning over 0, writing height data into memory, and processing the data.

1. Problems to be Solved and Attempted by the Invention] Only (, 5, As shown in FIG. 6, the incident light beam is
is reflected twice to form a light spot L, ,[,t,
Light spot 1. The image is formed on the light-receiving surface of PSD 14, and the 2p
! When the light spot images S1 and S are formed, the light spot position X obtained from the arithmetic circuit 20+ indicates the intermediate position between the light spot images S and It is not possible to measure height.

SUMMARY OF THE INVENTION In view of the above-mentioned problems, an object of the present invention is to provide a light spot position measuring device that can measure the light spot position related to the reflection of [J] once.

[Means for Solving the Problems 1 (1) First Invention FIG. 1 is a block diagram showing the principle configuration of the first invention.

In the figure, ■ is a front-end (n detector) (PSD), which outputs a pair of signals corresponding to the light position and received light intensity on its light-receiving surface 1.

Reference numeral 2 denotes an imaging optical means, which forms an image of a light spot on the inspection surface 31- on the light-receiving device of the optical position detector 1.

4 is a light shielding means, for example, it is composed of a light shielding plate and a mechanism for sliding it, or a liquid crystal shutter;
It is placed on the light-receiving surface of the SD1 to block a portion of the imaging light.

Reference numeral 5 denotes a light-shielding control means, which controls the light-shielding means 4 to adjust the light-shielding range in order to shield the imaging light from the virtual light spot outside the specified range.

(2) Second invention FIG. 2 is a block diagram showing the principle configuration of the second invention.

In the figure, 1A and 1B are the first and second optical position detectors (P
SD), and each outputs a pair of signals corresponding to the light position on the light receiving surface and the received light intensity.

2Δ and 2B are first and second imaging optical means, which direct the light spot on the inspection surface 3 to the first and second PSDs 1A and 2B, respectively.
The image is formed on the 2A light receiving surface. This second imaging optical means 2B
Further, the light spot L43, L, which is caused by the first reflection, is imaged at a specific position on the light receiving surface of the PSD 1B.

Reference numeral 6 denotes a light shielding member, which is disposed on this specific position on the light receiving surface of the second PSD, and blocks the imaging light directed to the specific position.

7 is a light position calculation means, which calculates the component related to the second reflection included in the output of the first PSD 1A,
By removing the output using the output of , the light spot position related to the first reflection is determined.

[Function] The incident light beam is reflected twice on the inspection surface 3, resulting in two light spots,
, L, is formed, in the first invention, the light spot related to the second reflection is not actually present, which is outside the specified range, for example, below the lower limit point of the inspection surface 3. Imaginary light point I4. Since the imaging light from ′ is blocked, PSD I
Only the image S of the light spot L1 related to the first reflection is formed on the light receiving surface of the light receiving surface.

Further, in the second invention, these light spots: 1. , 1 of
The light spot L1 due to the second reflection is not formed on the light receiving surface of the second PSD 1B, and the output of the second PSD 1B includes only information about the light spot due to the second reflection.

The component related to the second reflection included in the output of the first PSD 1A is removed using the output of the second PSD 1B.

Therefore, in any of these inventions, it is possible to measure the light spot position related to only the first reflection, which could not be measured conventionally.

[Example] Hereinafter, the present invention will be described in detail based on the drawings.

(1) First example FIG. 3 shows the optical system of the light spot height position measuring device.

The inspection surface IO includes the surface of the printed wiring board 10a placed on the X-Y stage 22, and the surface of the printed wiring board 10a placed on the XY stage 22.
The surface of a large number of chip components 10b is mounted on the surface of the chip component 10b.

The laser beam emitted from the laser 24 is transmitted through a galvano mirror.
26, and is irradiated onto the inspection surface 1O through the fθ lens 28 substantially perpendicularly to the printed wiring board 10a, thereby forming a light spot. When the galvanometer mirror 26 is angularly vibrated within a certain angle range by a current force meter type angular vibrator 30, the tip of the galvanometer mirror 26 scans over the inspection surface 10 to form a light cutting line 32.

The light spot is imaged on the light receiving surface of the PSDI 4 by the imaging lens 12. PSDI4 corresponding to the height direction of the light spot
If the direction on the light-receiving surface of PSDI4 is the X-axis direction,
On the axial end side, there is a light shielding plate 34 facing the light receiving surface.
A and 34B are arranged.

Arms 36Δ are provided at the base ends of the light shielding plates 34A and 34B, respectively.
, 36B are protruded, and the racks 38A, 38B formed on these are connected to pulse motors 40A, 40, respectively.
It meshes with the binions 42A and 42B attached to the rotating shaft of B. Therefore, the pulse motors 40A, 40
By driving the light shielding plates 34A, 34B
Move parallel to the receiving surface of IJ (PSDI 4,
The area of the light receiving surface of No. 4 changes.

As shown in FIG. 4, the incident light beam is reflected twice on the inspection surface 10, resulting in a light spot, I7. is formed, the light shielding plate 34
If there is no A, the light receiving surface of PSDI4 will have a light spot 146, L,
An image S,, S, is formed. The position of this light spot image S is the virtual light spot 14. which does not actually exist directly below the light spot S.
.

It corresponds to the height position. The imaginary light point L2° is located below the point L3 on the printed wiring board +Oa, and there is no problem even if the light spot formed by the imaging lens 12 is blocked by the light shielding plate 34A.

Therefore, in consideration of the height fluctuation within a small area of the printed wiring board 10a, the tip of the light shielding plate 34A is positioned slightly on the positive side of the X axis from the point S3 on the light receiving surface of the PSDI 4 corresponding to the point S3. A light-shielding plate 34A is placed there.

Here, the height of the surface of the printed wiring board 10a changes by about 2 mm at most due to its warpage. On the other hand, chip part 1
The height of 0b is about [1.4 to 2 ma+]. Therefore, it is necessary to slide the light shielding plate 34A depending on the height of the printed wiring board 10a at the optical scanning position. Therefore, the 1<)less motor 40A is controlled as follows.

That is, the current signal 18, l output from a pair of terminals of the PSDI 4 is supplied to the height position calculation circuit 44 to calculate the PS
The light spot image position X on the light receiving surface of DI4 is determined.

This position X is the same as the position X explained in FIG. 6, and the height position calculation circuit 44 is not shown in FIG. . Image position of the light spot on the inspection surface lO x 1 Height position of the light spot
is stored in the height memory 46 in accordance with the optical scanning position on the printed wiring fc1Oa. Printed wiring board 10
Since the change in the surface height due to the warpage of a is gradual, for example, the height of the end of the printed wiring board 10a where the chip component 10b is not strongly mounted (the starting end of each scanning line) is set as the reference height data. Height memory 46 by selection circuit 48
, and set this as the reference height X of this scanning line. It is then supplied to the light shielding plate control circuit 50.

The light shielding plate control circuit 50 drives the pulse motor 40A to slide the light shielding plate 34A, so that the tip of the light shielding plate 34A is
This reference height X above the photosensitive surface of PSDI 4.

It is located slightly closer to the X-axis stop direction than the position corresponding to .

On the other hand, the component maximum height setting device 52 has a chip Fl (product 1
A maximum height of 0b is set, and this set value is supplied to the light shielding plate control circuit 50. Since a light spot located at a position higher than Xo+hm is not formed by the first reflection, the light shielding plate control circuit 50 drives the pulse motor 40B to slide the light shielding plate 34B, and similarly to the above, the light spot is moved to (xo+ha). It is located slightly on the negative side of the X-axis from the corresponding position.

Note that the present invention may be configured without providing the light shielding plate 34B, the pinion 42B, and the component maximum height setting device 52.

Also, instead of the above-mentioned light-shielding mechanism, a liquid crystal display is used and the voltage application range is changed to change the light-shielding range to a! It may be a configuration in which all the components are adjusted.

(2) Second embodiment FIG. 5 shows a light spot height position measuring device according to a second embodiment.

The incident light beam passes through the half mirror 12C and reaches the inspection surface 10F.
is irradiated, is reflected twice and becomes a light spot on the inspection surface 105,
L, are formed, and these are converted into PS by the imaging lens +2A.
The light is focused on the light receiving surface of DI4A to form light spot images Sll and SIN. Also, light spots, I5. The reflected light is reflected by the half mirror 12G, passes through the imaging lens 12B, and is imaged on the PSDI 4r3.

PSD! A light shielding piece 54 is arranged at the center of the light receiving surface of 4B. No matter where the light spot L1 is located on the inspection surface +01, the light spot 15. The image Sy+ is always formed on the light shielding piece 54. That is, the imaging light of the light spot does not reach the light receiving surface of the PSD 14B. On the other hand, the light spot I1. Statue Set
is formed on this light-receiving surface.

The current signals taken out from the pair of output terminals of the PSD 14Δ are supplied to I/V converters +6A and +8A, respectively, and converted into voltages VI and L, which are supplied to an adder 56A and a subtracter 58A to obtain (V++V* ) and (v,
−v, ) is obtained.

Here, the light receiving intensities at the position of the light spot image S 11% 5its S1F are respectively Pl and PltSpat, and PS
D14A.

Similarly to the first embodiment, the light spot images S1.5lffi and Sx*(') positions are Xl on the light receiving surface of 14B,
, Xt.

When x3, the following equation holds true according to the principle of superposition.

L+ Vt= a (P+++ P+t)
' ” ” (1) L V*= a(P++
X++ P+tXt) ” ” ' (2
) Vs+ V4= b Ptt
・' (3) Vs-Va= b' Pt2X
* ・ ・ ・ (4) Here, 3
, b are constants. Also, ht and Pt.

are almost proportional, and X and X are almost proportional. Therefore, by appropriately setting 1 and K as constants, the following equation holds true.

L+L K+(Vs+Va)=aP++”
(5) V, -LL(X, -V,)-a P,,X,
---(6) Therefore, the position xI of the image Sl+ of the light spot due to one reflection of the inspection surface 10-1: is expressed by the following equation.

L = [L + Vt-L(Vs +V4))/(V
+ −Vt−Kt(V, +V4)) Then, the adder 56
B, the output value of the subtracter 58B is converted to a constant multiplier 60.6, respectively.
The output values of the adder 56A and the constant multiplier 60 are supplied to the subtracter 64 to obtain the value of the above equation (5), The output value of is supplied to the subtracter 66 to obtain the value of the above equation (6). Further, the output value of the subtraction 'a64.66 is supplied to the divider 68 to obtain the light spot height position x expressed by the above equation (7).

In particular, the device of the second embodiment has a light spot related to the first reflection and a light spot related to the second reflection to such an extent that it is difficult to limit the measurement area with a light shielding plate in the device of the first embodiment. This is effective when they appear close together.

It goes without saying that the above calculations may be executed by a software configuration using a microcomputer.

Furthermore, even if the positions x and Xs do not have a proportional relationship due to the arrangement of the optical system, it is sufficient if they have a constant relationship.

[Effects of the Invention] As explained above, even if the incident light beam is reflected twice on the inspection surface and two light spots are formed, the light spot position measuring device according to the first invention Since the imaging light from the light spot related to the reflection is blocked, only the image of the light spot related to the first reflection is formed on the light receiving surface of the PSD, and the light spot position measuring device according to the second invention , the output of the second PSD includes only the information of the light spot due to the second reflection, and the component related to the second reflection included in the output of the first PSD is from this second reflection.
Since it is removed using the output of the PSD, both inventions have the excellent effect of being able to measure the position of the light spot related to only the first reflection, which could not be measured conventionally. It greatly contributes to the accuracy of surface height measurement.

[Brief explanation of drawings]

FIG. 1 is a diagram of the principle of the first invention, and FIG. 2 is a diagram of the principle of the second invention. 3 and 4 relate to the first embodiment of the present invention, FIG. 3 is an optical system configuration diagram of a light spot height position measuring device, and FIG. 4 is an overall configuration of this light spot height position measuring device. It is a diagram. FIG. 5 is a configuration diagram of a light spot height position measuring device according to a second embodiment of the present invention. FIG. 6 is a configuration diagram of a conventional light spot height position measuring device. 6A, 56B are adders 8A, 58B, 64.66 are subtractors 0.62 is constant multiplier 8 is divider In the diagram, 10 is inspection surface 12. 12B is imaging lens 14, +4A, 14B is PSD 34A, 34B are light shielding plates 38A, 38B are rack 40A, 40B is pulse motor 42A, 42B is binion 50, light shielding plate control circuit 54 is light shielding piece L2 Principle of the first invention l! L/Figure Figure 1 Corner 30 t, φ, bird,! A diagram of the optical rod structure of the Shun 1 footing boat 1 (1st example) Figure 3 A diagram of the principle of the height measuring device 1 Figure 2 A diagram of the configuration of the height measuring device (prior art) Figure 6

Claims (1)

[Claims] 1) An optical position detector (1), and an imaging optical means (2) that images a light spot on the inspection surface (3) onto the light receiving surface of the optical position detector (1). and a light shielding means (4) disposed on the light receiving surface to shield a part of the imaged light, and the light shielding means to shield the imaged light from the virtual light point (L_2') outside the specified range. A light spot position measuring device comprising: (4) a light shielding control means (5) for controlling the light shielding range and adjusting the light shielding range. 2), a first optical position detector (1A), and a first imaging optical means (2A) that images a light spot on the inspection surface (3) onto the light receiving surface of the first optical position detector (1A). and the second
an optical position detector (1B), and a second optical position detector (1B) that detects the light spot on the inspection surface (3);
), and a second imaging optical means (2B) that forms an image on a light receiving surface of the light receiving surface, and a light spot (L_1) resulting from the first reflection among the light spots, on a specific position of the light receiving surface; a light shielding member (6) disposed on the specific position of the light receiving surface of the two-light position detector (1B) and blocking imaging light to the specific position; By removing the component related to the second reflection included in the output using the output of the second optical position detector (1B), the light spot position related to the first reflection is determined. A light spot position measuring device comprising: a position calculation means (7);