JPH0377005A - Device for measuring shape of object - Google Patents

Abstract

PURPOSE:To eliminate a dead angle and to accurately measure the external size of an object by arranging semiconductor position detectors in plural directions around the optical axis of a laser light beam which scans the object in plural directions by setting the optical axis thereof as center. CONSTITUTION:A stage 12 placed just under a laser light scanning part 11 can be moved in an X and Y directions by a driving device. An object placing part 12a is provided on the stage 12 and four sensor parts 13a-13d functioning as the semiconductor position detector are provided between the placing part 12a and a scanning part 11. As for the arrangement thereof, the four sensor parts 13a-13d are arranged on the diagonal lines 15a-15d of four imaginary planes 14a-14d in parallel with the optical axis (the optical axis at the time when a scanning quantity is zero) of the laser light beam from the scanning part 11. When the object is irradiated with the laser light beam, the reflected light therefrom is received by one or more of the sensor parts 13a-13d arranged around the optical axis of the laser light beam, so that the dead angle is not left and the accurate measurement is performed.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an object shape measuring device, and particularly to an object shape measuring device that uses a semiconductor device detector (PSD) to measure the shape of an object in a non-contact manner. Regarding.

In the past, there were basic ways to optically measure objects, such as electronic scanning using image devices such as television image pickup tubes and solid-state image sensors, and mechanical scanning using mirrors and reticles. Most of the methods were based on image scanning technology. When using such a scanning method, there is a drawback that the measurement sampling rate is determined by the scanning speed.

On the other hand, the position sensor head is an element that detects the device in the form of a light spot in a two-dimensional manner without using the above-mentioned scanning method.It has a fast response speed, and since it is not divided, it can detect the device continuously and can move at high speed. It has the advantage of being able to detect the movement of light spots at high speed.

A semiconductor device detector (PSD) used as a detector for a position sensor head has a uniform resistance layer on one or both sides of a high-resistance semiconductor surface, and a pair of electrodes for signal extraction at both ends of the resistance layer. configured. When light is applied to the resistive layer, the photogenerated current generated in the light incident device is split and extracted from a pair of electrodes, and the magnitude of the extracted current is opposite to the resistance value between each electrode and the incident device. Proportional.

That is, when a light spot is irradiated on the surface of the resistive layer (light receiving surface), a pair of currents (hereinafter referred to as r+, ig) having a current difference depending on the spot irradiation device can be extracted, and as a non-contact device sensor, For example, it is used in an object shape measuring device that inspects the mounting status and external appearance of surface-mounted components.

[Prior Art] As a conventional object shape measuring device of this type, as shown in a conceptual diagram in FIG.
age) and Q F P (Quad Flat Pac
A laser beam P+ is irradiated from directly above onto a surface mount component 2 such as a
It is known that the light is guided to the light receiving surface 4a of the D4 to form an image. According to this, since the height from the surface of the stage 1 to the reflection point A of the laser beam corresponds to the imaging device A' on the light receiving surface 4a, the two output currents 1+ and iz taken out from the PSD 4 can be calculated using the following formula The height ho can be determined by signal processing according to the following.

Furthermore, if the laser beam is scanned in a straight line, the height cross-sectional shape of the scanning section can be obtained. Furthermore, by moving the object in a direction perpendicular to the optical scanning, a three-dimensional shape of the optical scanning area can be obtained.

[Problem to be solved by the invention]

However, since such conventional object shape measuring devices are configured with only one PSD4, so-called blind spots are likely to occur in which reflected laser light cannot be received, making it difficult to determine the shape of the object to be measured. There was a problem in that it was not possible to perform a proper inspection.

[Purpose of the invention]

Therefore, an object of the present invention is to eliminate blind spots and accurately measure the external shape of an object by arranging PSDs in multiple directions.

[Means to solve the problem]

In order to achieve the above object, an object shape measuring device according to the present invention processes an output signal of a semiconductor device detector (PSD) that irradiates a laser beam onto an object and receives reflected laser beam from the object. In an object shape measuring device that measures the shape of an object by scanning the object, the semiconductor device detectors are arranged in a plurality of directions around the optical axis of a laser beam that scans the object in a plurality of directions. , is configured to measure the shape of an object based on output signals from a plurality of semiconductor device detectors.

(Function) In the present invention, when a laser beam is irradiated onto an object, the reflected light is received by one or more of a plurality of semiconductor device detectors arranged around the optical axis of the laser beam. It is possible to accurately measure the shape of the object to be measured without causing such problems.

(Example〕 Hereinafter, the present invention will be explained based on the drawings.

1 to 9 are diagrams showing an embodiment of an object shape measuring device according to the present invention.

In FIG. 1, 10 is a laser light source unit, 1 is a laser beam scanning section, and the laser beam scanning section 11 includes an X-direction galvano mirror 11x, a Y-direction galvano mirror 11f, and a scanning lens lla. X direction galvano mirror 1
The 1x and Y direction galvano mirrors 11 are each driven by a driving source M.
x and My, rotate independently, and direct the laser beam in the X direction and Y
Scan in the direction. On the other hand, 12 is a stage placed directly below the laser beam scanning section 11, and the stage 12 is movable in the X direction and the Y direction by a drive device (not shown). Measurement object placement sections 12 and 3 are provided on the stage 12, and four sensor sections 13a to 13d are provided between the measurement object placement section 12a and the light scanning section 11 indicated by L. There is. Here, the desirable ti'B of these four sensor parts 13a to 13d are as follows.

That is, in a fund assuming four planes 14a to 14d parallel to the optical axis of the laser beam from the laser beam scanning unit 11 (optical axis when the scanning amount is zero), diagonals 15a to 15d of each of these planes are assumed. On the top, four sensor parts 13a ~
13d are respectively arranged.

FIG. 12 is a conceptual diagram showing one sensor section (for example, 13a), and the sensor section 13a has an optical lens L1 and a PSD similar to the conventional example.

FIG. 3 is a system diagram of the signal processing system, which includes four sensor sections 13a.
Each output current from ~13d, Iz(IX4,1.
four selectors 16a to 16d that select X4) in combination according to command signals S and -s4, and selector 16
Combination signal and brightness N3 from a”-・16d
(P=1.+Iz) four height calculation circuits 17a-17cl and four height calculation circuits 17a"17
Three synthesis circuits 1.8 which combine the calculation results of d, output height data l)h, and synthesized brightness data Dp.
a to 18c, an image memory 19 that stores composite product quality data Dh and composite brightness data Dp as image data.
and a CPU 20 that processes the image data in the image memory 19 and measures the shape of the object to be measured, and controls each part of the system. In addition, CPU20
From then on, the X-Y drive command signals 5x-y are applied to the drive and moving parts of the X-Y stage, and the X-galvano mirror X direction scanning 0N10FF 9/.41, direction command signal X.

75, Scanning axis/offset signal WXL10□, , Y direction scanning ON10 F F
Signal YON10FF, direction command signal Y. /-2 scan width・
Outputs an offset signal YL10FFSET. FIG. 3 is a diagram without showing the configuration of the synthesis circuits 18a to 18c.
1 to 3 are comparators that output H level when 10 inputs are larger than the input, SEL 1 to 5 EL4 are selectors that select 6 inputs if the S input is I (level), vl is a standard corresponding to the required light amount The voltage V2 is a reference voltage corresponding to the maximum amount of light.
The two brightnesses Pa and Pb are compared, and the darker one (height signal) is selected and output as a selected height signal. For example, Pa>P
When h (Pb is dark), select 1, hb. Carrier 7,
When either Pa or Pb is less than V (required light amount), one of Pa or Pb is ignored and the height of the other side (the side exceeding V) is selected.

In such a configuration, for example, a QFP is placed on the stage 12 as an object to be measured, and its lead shape in four directions is inspected. First, the stage 12 is moved to place the lead on the predetermined side of the package directly F of the laser beam scanning section 11, and the laser beam scanning section 11 scans the laser beam from the laser light source unit 10. When the scanning of the laser beam is detected by each PSD of the sensor sections 13a to 13b, the output currents 11.12 from each of the sensor sections 13a to 13b are appropriately combined, then subjected to signal processing, and the results are combined. The image is stored in the image memory 19.

Here, for example, a sensor section 13 is attached to one side of the package.
If b is the device, the opposite side of the package becomes a blind spot when viewed from the sensor section 13b. That is, when an attempt is made to inspect the lead shape on the opposite side, the sensor section 13b cannot receive the reflected laser light, and the inspection cannot be performed. However, in this embodiment, since sensors are provided in multiple directions, even if a blind spot occurs when viewed from one sensor,
The reflected laser light can be received by other sensors without any trouble, and the above-mentioned problem can be eliminated.

Further, in this embodiment, measurement can be performed using sensors in each direction alone or in combination. 5th to 9th
The figure is for explaining measurements from various directions.
In the figure, the scanning direction is the X direction (Oo), and unidirectional measurement from the front side (a), unidirectional measurement from the back side (b),
In Figure 6, the scanning direction is the Y direction (90°), and the one-way measurement from the right side (a), the one-way measurement from the left side (b), and the one-way measurement from both sides are shown in Figure 6. Measurement and synthesis (C), Figure 7 shows the scanning direction (45
°), one that measures and synthesizes from the front side and right side, respectively (a), and one that measures and synthesizes from the back side and left side (b)
), one that measures from all four directions and selects and synthesizes them (C), Figure 8 shows the scanning direction set to (135°), and examples of Figure 7 (a), (b), and (c). is rotated by 90 degrees.

In addition, in Fig. 9, the scanning direction is (30°), and in this case, even if the object is horizontal, (a) and (b)
As shown in FIG. 2, when only one side is measured, the height is gradually measured higher in case (a) and gradually lower in case (b). Therefore, as shown in (C), by measuring from both sides and adding and combining the two measured values, the correct height can be obtained.

In addition, in the synthesis circuit of the above embodiment, conditional selection is performed such as selecting the darker one (below VZ) among the brightnesses exceeding 1, but in addition to this, various synthesis methods such as those listed below are performed. There are possible ways. In other words, ■ Simply select the brighter one, ■ Simply select the darker one, ■ Conditionally select the brighter one (below VZ), ■
Conditionally selecting the darker one (method of the above embodiment), etc.

Incidentally, each of the above methods (1) to (2) has the following advantages.

Method ① is effective for eliminating shadows.

Method (1)9 is preferably used in special cases where the target is metal, etc., and the accuracy is better in the dark.

Method ■ is effective for eliminating shadows, and basically choose the brighter side. However, if the signal strength exceeds a certain value, the darker one is selected. This has the advantage that the processing circuit's power range (the range of signal strengths that can be processed) is small. ■
This method selects the darker one if the signal strength is greater than the required signal strength.

These additions (1) to (2) or two height data are added to form one height data.

Note that it goes without saying that the above synthesis methods can be used depending on the detection method, the conditions of the measurement target, etc.

(Effects of the Invention) According to the present invention, since the PSDs are arranged in multiple directions, blind spots can be eliminated and the appearance inspection of the object to be measured, for example, height measurement, can be performed correctly.

[Brief explanation of drawings]

1 to 9 are diagrams showing an embodiment of the object shape measuring device according to the present invention, FIG. 1 is a configuration diagram of its optical system, FIG. 2 is a configuration diagram of one of its sensors, and FIG. 3 is a block diagram of the signal processing system, Figure 4 is a block diagram of one of the synthesis circuits, Figures 5 to 9 are diagrams showing the various measurement patterns, and Figure 10 is the concept of the optical system showing a conventional example. FIG. 13a-13d...Sensor section, PSD...
...Semiconductor device detector. Configuration diagram of an optical system in one embodiment Figure 1 Configuration diagram of two sensors Configuration diagram of one synthesis circuit Figure 3 Configuration diagram of a signal processing system Figure 3 (a) (b) (C) (d) (b) (C) (d) (b) (C) (6) (,b) (C)

Claims (1)

[Claims] An object shape measuring device that measures the shape of an object by irradiating a laser beam onto the object and processing the output signal of a semiconductor device detector (PSD) that receives reflected laser light from the object. In the method, the semiconductor device detectors are arranged in a plurality of directions around the optical axis of a laser beam that scans the object in a plurality of directions, and the semiconductor device detectors are arranged based on the output signals of the plurality of semiconductor device detectors. An object shape measuring device characterized in that it is configured to measure the shape of an object.