JPH01308905A - Measurement of shape and apparatus for shape recognition at high speed using semiconductor position detector - Google Patents

Abstract

PURPOSE:To shorten a measuring time and to perform highly accurate measurement by moving a beam spot applied to an object to be measured on the surface of the object to be measured through a luminous flux position altering means to scan the surface of said object. CONSTITUTION:The projected beam from a semiconductor laser 1 is condensed by projection lens groups 2, 3 to be applied to an object (a) to be measured as a small beam spot and the reflected beam f1 from the object (a) to be measured is condensed to one point on the beam receiving surface of a two-dimensional semiconductor position detector (PSD) 7 through a beam receiving lens 6 and a luminous flux position altering means 4 is constituted on the optical axis in the vicinity of the projection lens groups 2, 3. When the object (a) to be measured is displaced to the position a1 shown by a broken line, the angle of the incident beam f2 to the beam receiving lens 6 is changed and, therefore, the condensed beam spot on the PSD 7 is moved in proportion to the displacement (L1-L2) of the object (a) to be measured. As a result, when the position of the condensed beam spot on the PSD 7 is clarified, the distance L up to the object (a) to be measured can be calculated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a non-contact inspection technique for a measurement object, and relates to a high-speed shape measurement method using a semiconductor device detector and a high-speed shape recognition device.

[Conventional technology] Non-contact technology has traditionally been used in many industrial fields, such as shape recognition of high-temperature, high-speed moving objects in steel plants, and measurement of the dimensions or displacement of fragile objects in the mechanical and electrical industries. Therefore, there is a need for a distance sensor that is highly accurate and capable of high-speed response. Therefore, as this type of non-contact distance sensor, a triangulation type laser distance sensor using laser light has been put into practical use as an optical distance sensor, especially due to the rapid progress of optical devices. Various measurement devices using a triangulation method using sensors have been developed.

As shown in FIG. 7, the laser distance sensor is as follows:
A small, high-output semiconductor laser 50 and a semiconductor device detector 51 (Po5itio
A device in which the projection light from the semiconductor laser 50, which is focused by the projection lens 53, is irradiated onto the measurement target a as a small spot light f1 is known. The structure is such that the reflected light f2 from a is focused on one point on the light-receiving surface of the semiconductor device detector 51 by the light-receiving lens 54. In this way, the distance to the object to be measured a can be determined by the displacement of the focused spot on the semiconductor device detector 51.

[Problems to be Solved by the Invention] However, with the above-mentioned conventional technology, it is possible to detect points with high accuracy by narrowing the light spot as narrowly as possible, but when detecting a point with a relatively large area, There is a problem in that the smaller the light spot is, the longer it takes to scan a surface with the light spot in order to measure it.

For example, when drawing a pattern on an electrical board, the unevenness of the board is measured in advance, and at the same time the results are fed back to the drawing head, and the distance between the board and the drawing nozzle is maintained constant by driving the drawing head up and down. However, in this case, the height measurement point measured using a single light spot as described above does not have to be scanned by moving the board on the side to be measured using a moving table (X-Y table) each time the measurement is performed. However, when a 5C11 square substrate was scanned and measured with a 100 μm light spot without any gaps, it took about 4 minutes to measure.

The present invention has been made in view of the above-mentioned pressure, and provides a high-speed shape measurement method using a semiconductor device detector, which can shorten measurement time and perform highly accurate measurements in surface inspection of objects to be measured. The purpose is to advocate the
It is an object of the present invention to provide a high-speed shape recognition device for carrying out the measurement method.

[Means for Solving the Problems] A method for high-speed shape measurement using a semiconductor device detector according to the present invention focuses the reflected light of a light spot irradiated onto a measurement object on the light receiving surface of the semiconductor device detector to form a triangular shape. In the method of measuring the height of the irradiation surface of the object to be measured by surveying calculations, the light spot irradiating the object to be measured is scanned and moved on the surface of the object to be measured via a beam position changing means; The gist of this method is to read the output values from the semiconductor device detector at each scanning movement step, and to obtain a group of output values obtained by adding a predetermined calculation to the output values as measured values.

Further, as a structure embodying the above method, a light beam position changing means for scanning and moving a light spot irradiated onto the surface of the object to be measured is inserted on the light beam between the light source and the object to be measured, and A synchronous arithmetic circuit can be configured downstream of the semiconductor device detector to read the output value for each scanning movement step and perform a predetermined arithmetic operation on the output value.

[Operation] As shown in FIG. 1, the principle of the present invention is that the projection light from the semiconductor laser 1 is focused by the projection lens group 2.3 and irradiated onto the measurement object a as a small light spot f1. The reflected light f2 from the measurement object a is condensed to one point on the light receiving surface of the two-dimensional PSD 7 (hereinafter referred to as PSD 7) by the light receiving lens 6, and the light emitting lens groups 2 and 3 are A beam position changing means 4 is constructed on the nearby optical axis. Here, when the measurement object a is displaced to the a1 position shown by the broken line, the angle f2 of the incident light to the light receiving lens 6 changes, so the focused spot on the PSDT is proportional to the displacement (LI L2) of the object a. Since it is moving, PSD7
If the position of the upper focal spot is known, the distance to the object to be measured a can be determined.

As shown in Fig. 1, the distance is 8D = Distance between light emitting and receiving parts F: Distance between light receiving lens 6 and PSD 7. Fig. 2 is a cross-sectional explanatory diagram of a semiconductor device detector (-dimensional PSD). Both sides are formed by a uniform resistance layer, and a pair of electrodes A for signal extraction are provided at both ends of the resistance layer.
B is provided to generate a photocurrent due to the photoelectric effect. Let the distance between the picture electrodes A and B be j, the resistance be the distance, the distance from the electrode A to the light incident position be X, and the resistance of that portion be Rx.

The photogenerated current IO generated at the light incident position is divided inversely proportional to the resistance value up to each electrode, and the extracted currents Ia and Ib are calculated as follows: The resistance layer is uniform, and the length and resistance value are proportional to each other. Then, (Equation 21 becomes as follows.

(From type 31 , and L is determined by equation (1).

According to the above method and structure, the beam position changing means scans and displaces the light spot from the light source irradiating the object to be measured in one direction, moves the movable table in parallel from the other direction, and further scans in one direction. It can be displaced and irradiated sequentially in this way, and the P
By reading the output of the SD in correspondence with scanning, the measurement speed can be increased.

[Embodiment] Hereinafter, a preferred embodiment of a high-speed shape recognition apparatus that implements a high-speed shape measurement method using a semiconductor device detector according to the present invention will be described with reference to the drawings.

FIG. 1 shows a first embodiment of an optical system of an apparatus showing the principle of the present invention. On the optical axis between the laser 1 and the object to be measured 8, two sets of projection lens groups 2.3 are provided for controlling the irradiation of the light beam onto the object to be measured a. A beam position changing means 4 which is orthogonal to the optical axis is inserted between . The structure is such that the light beam f1 focused on the object 8 is scanned over the surface of the object to be measured. Reference numeral 6 denotes a light-receiving lens that receives a reflected light flux f2 of the light flux f1 irradiated onto the measurement object a;
As shown in FIG. 3(a), the optical system having the above structure in which the PSD 7 is fixed as a position detection device at the rear focal position of the semiconductor laser 1 electrically converts the beam projected from the semiconductor laser 1 by the beam position changing means A spot light flux f s (CHl, CH2・
...CHn) and (first scanning position b)
, move the moving table A on which the measurement target is placed in the -X direction,
Set the second scanning position C to the first scanning position (Fig. 3(b)), then scan in the Y direction, and then perform the same scanning to obtain the position shown in Fig. 3(e). Scanned as shown. In addition, in FIG. 3(c), if it is necessary to measure downward from the W line, the same method as above may be repeated.

In this way, the position of the reflected light beam f2 of the spot light beam f.1 is detected by the PSD 7 via the light receiving lens 6, and the height position of the surface a of the object to be measured can be measured by arithmetic processing using the method described later.

Here, in addition to the scanning method using the luminous flux changing means 4 shown in FIG. 3, the scanning method is changed to a spot luminous flux f1 that scans in the X direction, and the movable table A is moved in the -Y force direction to sequentially irradiate in the same manner. You can.

FIGS. 4(a) and 4(b) show a configuration in which a large number of liquid crystal shutter portions 9 arranged in matrix are sequentially scanned and opened by an electronic drive control circuit 5, as the light beam position changing means 4 of the optical system. It shows an embodiment in which a liquid crystal shutter shutter 8 is provided, (a> figure is a partial perspective view, (b) is a partial perspective view).
) is a cross-sectional explanatory diagram of the figure.

FIG. 5 shows a first embodiment of the present invention, in which the semiconductor laser 1 is connected to a light emission signal output port 11 configured in a central control unit CPU via a semiconductor laser drive circuit 12, Laser light is irradiated at predetermined timing. Further, the liquid crystal shutter 8 is connected to an output port 14 of a central control unit CPU via a liquid crystal control circuit (liquid crystal shutter controller) 13. The PSD 7 outputs, for example, output currents Ia and Ib by switching them with an analog switch 17 via a preamplifier 15.16, and
It is connected to the input port 20 of the central control unit 'II CPU through a sample and hold circuit 18 and one analog/digital conversion circuit.

Reference numeral 21 is an input/output port 22 of the central control unit 1fcPU.
This is an output display unit for inputting/outputting mode settings or status display connected to the unit, as well as displaying measured values.

In the high-speed shape recognition device having the above configuration, the shutter part 9 of the liquid crystal shutter 8 is connected to the light beam f1 as shown in FIG. 4(b).
Since the structure is such that the irradiation position of the light beam f on the measurement target a is changed by scanning so that a part of the light beam f passes through, the numerical data < D, F) can be used for processing calculations to obtain respective position measurements.

That is, the scanning speed is determined by the response speed of the liquid crystal shutter 8, but since it does not have a mechanical drive mechanism, it is possible to measure the luminous flux.

Furthermore, since the processing circuit described above has a structure in which the output from the PSD 7 is routed through the same analog circuit by switching the analog switch, variations in signal values can be prevented. The output signal is A/D converted from the analog section and calculated by the central control unit ZCPU of the digital section according to the triangulation method, so that distance information can be obtained.

In addition, in the two-dimensional PSD, in addition to XI and X2, yt
, Y2, the same type of preamplifier 15°16, analog switch 17. Sample hold circuit 18. The circuit configuration connected to the input port 20 of the central control unit CPU via the analog/digital conversion circuit 19 is omitted.

Next, FIG. 6 shows a second embodiment of the beam position changing means 4 of the optical system.

In place of the liquid crystal shutter 8, a voice coil 25 having a reflecting mirror 23 for the light flux f1 is arranged in the vibrating section, and the voice coil 25 is a voice coil drive connected to the output port 27 of the central control unit CPU. The light flux f connected through the circuit 29 and reflected by the reflecting mirror 23
One light spot is driven to scan the surface of the object to be measured. Furthermore, the coil current of the voice coil 25 is output to the central controller & cPU via the position detector 31 and the input boat 30, and at the same time, the result is sent to the voice coil 25.
5 to enable highly accurate luminous flux measurement. In addition, it is also possible to use a linear scale to detect the amount of movement and control it to a predetermined amount of movement. The other configurations are the same as those of the first embodiment. In the first and second embodiments, the output terminal Xr X2 of the PSD 7, the preamplifier after Y+-Y2, the analog switch, the sample hold circuit, the analog/digital conversion circuit input port, the central control unit CPU, etc. These components form a synchronous arithmetic circuit.

Furthermore, as described above, the light beam position changing means 4 for carrying out the present invention is not limited to one having a structure in which the liquid crystal shutter 8 or a reflecting mirror is disposed in the vibrating part of the voice coil 25, but also a plurality of light beams emitting spot-like light beams. A scanning structure is created by arranging multiple semiconductor lasers in parallel, a scanning structure is created by arranging the light emitting ends of many optical fiber cables led out from a light emitting part, and a device such as a rotating polygon mirror is used to change the angle of the light beam and displace it. It can also be a structure.

In the above embodiment, the semiconductor laser 1 is used as a light source to obtain a light spot for irradiating the PSD 7, but in the present invention, an LE is used instead of the semiconductor laser.
A light emitting element such as D can also be used. Furthermore, by using the distance sensor of the present invention, the shape of the object to be measured can be recognized at high speed by moving the sensor in the axial direction of the object to be measured, which rotates around the axis, and measuring the distance.

[Effects of the Invention] As described above, according to the high-speed shape measurement method and high-speed shape recognition device using a semiconductor device detector according to the present invention, the light beam position changing means scans the light spot irradiated onto the measurement target. This makes it possible to accurately obtain the height position information of the shape without having to move and scan the measurement object each time it is measured, which is a feature that greatly improves the measurement speed. It is particularly useful in detecting the height of printed circuit boards, recognizing shapes, etc., and the practical effects after implementation of the present invention are extremely large.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of an optical system showing the principle of a high-speed shape measurement method using a semiconductor device detector according to the present invention, Fig. 2 is a cross-sectional explanatory diagram showing the principle of a semiconductor device detector, Fig. 3(a),
(b) and (c) are explanatory diagrams showing the scanning method using the beam position changing means, and FIGS. 4 (a) and (b) are perspective views and cross-sectional explanations of the liquid crystal shutter showing the beam position 1 changing means of the same optical system. 5 is a block diagram of the arrangement of the optical system and the control system showing the first embodiment of the device of the present invention, and FIG. 6 is the arrangement diagram of the optical system showing the beam position changing means of the second embodiment. and a block diagram of the control system, and FIG. 7 is a layout diagram of the optical system using the conventional triangulation method. 1... Semiconductor laser 2. 3... Projection lens group 4... Luminous flux position changing means (liquid crystal shutter 8° reflector 23. voice coil 25) 5... Electronic drive control means (liquid crystal control circuit 13)゜Voice coil drive circuit 29) 6... Light receiving lens 7... PSD 12... Semiconductor laser drive circuit 17... Analog switch 18... Sample hold circuit 19... Analog/digital conversion circuit 21. ...Output display unit CPU...Central control unit a...Measurement object Name of applicant Tokyo Heavy Equipment Industry Co., Ltd. Figure 1 Figure 2

Claims (2)

[Claims] (1) The reflected light of the light spot irradiated on the object to be detected is focused on the light receiving surface of the semiconductor device detector, and the relative height of the light spot irradiated surface of the object to be measured is determined by the triangulation method based on the displacement of the light receiving position. In the method of measuring the surface of the object, the light spot irradiated onto the object to be measured is scanned and moved on the surface of the object to be measured via a beam position changing means;
A high-speed shape measurement method using a semiconductor device detector, in which output values from the semiconductor device detector are read at each scanning movement step, and a group of output values obtained by adding a predetermined calculation to the output values is used as a measurement value. (2) The reflected light of the light spot irradiated on the measurement target is focused on the light receiving surface of the semiconductor device detector, and the relative height of the light spot irradiation surface of the measurement target is determined by triangulation based on the displacement of the light receiving position. In the device for measuring the surface area, a light flux position changing means for scanning and moving a light spot irradiated onto the surface of the measurement object is inserted on the optical axis between the light source and the measurement object, and the semiconductor device detector A high-speed shape recognition device using a semiconductor device detector comprising a synchronous arithmetic circuit that reads an output value at each scanning movement step and adds a predetermined arithmetic operation to the output value at a subsequent stage.