JPS60225002A - Measuring method of position - Google Patents

Abstract

PURPOSE:To contrive the measurement of X-Y coordinates, i.e. a two-dimentional position, with simple signal processing and with only one measuring operation, by combining a one-dimentional image sensor with a triangular position detecting mark. CONSTITUTION:A triangular position detecting mark 2 provided so that the perpendicular line connecting one vertex, as a reference point, with one side is made parallel to the direction of one axis of a work piece 1 to be measured, and a one-dimentional image sensor 4 disposed around the reference point of said mark 2 as the center and in the direction of the other axis of the work piece 1, are provided in a part on the work piece 1. When the work piece 1 is displaced from a reference position 0 to an arbitrary position of X-Y coordinates, the sensor 4 photographs the mark 2 of an equilateral triangle on the work piece 1. On the occasion when this sensor 4 is scanned from a zero bit sequentially, cross pulses corresponding to the number of bits from said zero bit to the detection of the mark 2 are computed, while the pulses corresponding to the distance of the mark 2 detected by the sensor 4 are computed. Based on the results of these computations, the two-dimentional position of the work piece 1 is measured.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method for measuring the position of a workpiece relative to the machine in an automatic machine, etc., and in particular to a method for measuring the two-dimensional position of a workpiece, so-called XY coordinates, using a one-dimensional image sensor. It relates to a position measurement method for measuring .

[Prior art]

Conventionally, in automatic machines, etc., the XY of the workpiece relative to the machine
Image pickup tubes such as vidicon and two-dimensional image sensors are used to measure coordinate positions, but when these sensors are used, the control circuits and signal processing tend to be complicated, and they are also costly. There was a problem. 7, a position measurement method using a one-dimensional image sensor using a solid-state element such as a MOS type or COD has also been adopted. This method has the advantage that a one-dimensional image sensor can be used easily and is faster, but due to the structure of the one-dimensional image sensor, it can only detect signals in the direction in which the sensor elements are arranged. This method had the disadvantage that it could only measure .

[Summary of the invention]

The present invention has been made in view of these circumstances, and its purpose is to provide a position measuring method that makes it possible to measure two-dimensional positions using a one-dimensional image sensor.

In order to achieve such an object, the position measuring method of the present invention places a perpendicular line connecting one vertex and one side of a part of the workpiece to be measured in one axial direction of the workpiece with one vertex as the base point. Triangular position detection marks provided in parallel,
With respect to this position detection mark, a mark 1 is disposed in a direction perpendicular to the other axis of the workpiece with the base point of the cough mark as the center.
a dimensional image sensor, the image sensor is
When sequentially scanning from a bit, clock pulses corresponding to the number of bits from the 0 bit to detecting the mark are counted, and pulses corresponding to the number of bits corresponding to the distance of the mark detected by the image sensor are counted. By counting, two parts of the workpiece are calculated based on these counting results.
It is designed to measure dimensional position. Hereinafter, the present invention will be explained in detail based on the drawings.

〔Example〕

1 and 2 respectively show a schematic configuration of a measurement system and the relationship between its one-dimensional image sensor and position detection marks in order to explain the principle of the position measurement method according to the present invention. In these figures, 1 is a workpiece for positioning to be measured, 2 is a triangular position detection mark provided on a part of this workpiece 1, and this mark 2 is as shown in FIG. , the length of one side is A, and the length on the perpendicular line connecting one vertex and one side is B, then these ^ and B are 1=12.
An equilateral triangle is formed, and this mark serves as a reference for positioning. In this case, when the reference position at which the workpiece 1 is to be positioned is O, the position detection mark 2 has one vertex on one axis of this reference position 0, that is, the Y axis, as the base point F, and the position detection mark 2 A perpendicular line connecting the sides is parallel to the other axis of reference position 0, that is, the x-axis. In the example shown in FIG. 2, the position detection mark 2 is a white background, and the surrounding area is a black background (shaded area).

Further, 3 is a measurement optical lens, and 4 is a 512-bit one-dimensional image sensor made of a solid-state device such as a MOS type or CCD, which detects the position detection mark 2 imaged on the light receiving surface 5 through this lens 3. Yes, this image sensor 4 is located at the base point F of the position detection mark 2.
The sensor element is arranged in parallel with the Y-axis direction, and the O-th bit of the sensor element corresponds to the reference position on the OOX axis. Note that in FIG. 2, reference numerals indicate the field of view of the one-dimensional image sensor 4.

In such a measurement system, when the workpiece 1 is displaced from the reference position 0 to an arbitrary XY coordinate position as shown in FIG. The detection mark 2 is imaged through the optical lens 3, and only the area between the two points α and β of the mark is brightly imaged on the light receiving surface. At this time, the one-dimensional image sensor 4 is
When scanning bits sequentially, this image sensor 4
As shown in FIG. 3, the signal is at a low level from the O-th bit until point α of the position detection mark 2 is detected.
From point α to point β, a high level signal corresponding to the bit of each sensor element is detected as an image signal. Therefore, if we define the number of bits until the one-dimensional image sensor 4 detects a high level signal from 0 bit as C2 and the number of bits only at high level as D, then we can know the position on the X axis from the reference position O. can be calculated if the number of bits mentioned above is known.

In other words, the position on the X axis (deviation from the reference position 0) is
, where n is the magnification of the measurement optical lens 3 and P is the element pitch of the one-dimensional image sensor 4, this position X can be determined by the following equation.

x = DX - However, this ratio does not have to be 1:1.
:2 or 1:4 may be used. However, at this time (coefficient n
= ) It is necessary to multiply the above equation (1) by B/A. Also, to know the position on the Y-axis from the reference position 0, the value of the bit number C and the value of the bit number must be 1/l! It can be calculated if you know what is added. That is, assuming that the position on the Y axis (deviation from the reference position O) is y, this position y can be determined by the following equation.

y=('c+D/2)x-XP (2) FIG. 4 is a block diagram of a measuring circuit for explaining an embodiment of the position measuring method according to the present invention. Here, as mentioned above, 7'
5(a) and (b) from the drive circuit 11 to the start terminal S and clock terminal CL of the one-dimensional image sensor 4.
When a start pulse SP and a clock pulse φ shown in FIG. At this time, workpiece 1 to be measured
As shown in FIG. 2, when the reference position O is also displaced to an arbitrary XY coordinate position, the one-dimensional image sensor 4
High-level signals corresponding to the bits of each element corresponding to the isosceles triangular position detection mark 2 on the workpiece 1, that is, its two points α and β, are serially detected as image signals.

Then, when this image signal is amplified by the amplifier circuit 12 and inputted to the comparison circuit 13, the fifth image signal amplified by the amplifier circuit 12 is
The image signal Va shown in Figure (e) is compared with the reference voltage Er of the comparison circuit 13 and converted into a binary signal. This results in
As shown in FIG. 5(d), the comparison circuit 13 outputs a pulse Vd corresponding to each bit corresponding to the distance rc between the two points α1β of the position detection mark 2.

On the other hand, the set terminal S of the R8 type flip-flop 14 is input with the start pulse SP from the drive circuit 11, and the reset terminal R thereof is input with the output pulse Vd of the comparator circuit 13. ) is applied to SP"t'-, and comparison circuit 1
A reset is applied with the output pulse Vd of 3. Therefore, the output Q of the 7-lip flop 14 becomes a pulse corresponding to the time width from the start pulse SP for starting the image sensor 4 until the point α of the position detection mark 2 is detected. As a result, the output pulse Q of the 7-rip 70-tube 14 and the clock pulse φ of the drive circuit 11 are logically ANDed in the AND circuit 15, and the output from the AND circuit 15 is as shown in FIG. 5(e). As shown, the point α at which the position detection mark 2 is detected from the θ-th bit of the image sensor 4
Clock pulses vc corresponding to the bits up to are taken out.

Each output pulse Vd extracted in this way,
The clock pulse Vc is passed through the selector 16 to the counter 1.
When input to T, this counter 17 sequentially counts the clock pulses Vd shown in FIG. The number of pulses is 20 points α for position detection marks from the start pulse sp.
The number of bits C of the one-dimensional image sensor 4 until it detects
(See Figure 3). Further, when the selector 16 is in the select state of the terminal sb, the counter 17 sequentially counts the output pulses Vd shown in FIG. For position detection detected by -ri2 points α and β
This corresponds to (g) (see Figure 3). Therefore, based on each pulse IC, D counted by this counter 17, (1)
By calculating the equation and equation (2), the XY coordinate position x+y of the workpiece 1 displaced from the reference position O can be measured.

Note that the counter 1T has a reset terminal (RESET).
The one-dimensional image sensor 4 described above may be of a type other than 512 bits as long as it is reset by the start pulse SP of the drive circuit 11 that is input to the 1-dimensional image sensor 4.

〔Effect of the invention〕

As explained above, according to the present invention, the combination of a one-dimensional image sensor and a triangular position detection mark enables XY coordinate position detection with simple signal processing and only one measurement, resulting in low cost. It is possible to perform high-accuracy and high-speed position measurement, and therefore has excellent effects when applied to positioning mechanisms of various automatic machines, robots, inspection devices, etc.

[Brief explanation of the drawing]

1 and 2 are a schematic configuration diagram of a measurement system for explaining the principle of the position measurement method according to the present invention, and a diagram showing the relationship between its one-dimensional image sensor and position detection marks;
The figure shows signals corresponding to each bit when a position detection mark is detected by the one-dimensional image sensor, and FIG. 4 is a block diagram of a measurement circuit for explaining an embodiment of the position measurement method according to the present invention. 5(a) to 5(e) are time charts of the main parts in FIG. 4. 1. Ken, work to be measured, 2. @fist@triangular position detection mark, 3... optical lens for measurement, 4e...
- One-dimensional image sensor, 11... Drive circuit, 12
...Amplification circuit, 13...- Comparison port m, Book 14...
Fist flip-flop, 15... logical product circuit, 16...
...Selector, 17...Threat/Counter. Patent Applicant Ise Electronics Co., Ltd. Agent Masaki Yamakawa (and 2 others) Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] A triangular position detection mark is provided on a part of the workpiece to be measured with one vertex as the base point and a perpendicular line connecting the vertex and one side parallel to one axial direction of the workpiece, and this position. A one-dimensional image sensor is provided that is arranged in a direction perpendicular to the other axial direction of the workpiece with the reference point of the mark as the center for the detection mark, and when the image sensor is sequentially scanned from the O bit, Counting clock pulses corresponding to the number of bits from the O bit to detecting the position detection mark, and counting pulses corresponding to the number of pits corresponding to the distance of the position detection mark detected by the image sensor. A position measuring method characterized by measuring the two-dimensional position of the workpiece based on these counting results.