JP2007205807A - Detection sensor and shape measuring method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a detection sensor and a shape measuring method allowing to eliminate alignment of a two-dimensional imaging device or the like in shape measurement. <P>SOLUTION: The area of an imaging area 13A of a CMOS image sensor 13 is set to be larger than an irradiatable area in which reflected light from an object under measurement W can be irradiated on the imaging area 13A when performing the measurement of the object under measurement W. A measurement use pixel to be used in the measurement is selected on the basis of the light receiving position of the reflected light, out of light emitted from a light emitting section 11 prior to the measurement by a CPU 14, from the object under measurement W on the imaging area 13A. The measurement of the object under measurement W is performed on the basis of the level of a light receiving signal Sb of the measurement use pixel. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a detection sensor and a shape measuring method.

For example, as shown in FIG. 2, the detection sensor irradiates the surface of the measurement object with light emitted through a slit plate and receives the reflected light with a two-dimensional image sensor. There is. The irradiation image formed by the reflected light on the two-dimensional imaging device has the same shape (for example, a straight line shape) as the opening shape of the slit as long as the surface of the measurement object (irradiated surface) is flat. On the other hand, when the surface of the measurement object has irregularities, it has a shape corresponding to the irregularities. Therefore, the surface shape of the measurement object can be detected (measured) based on the irradiation image on the two-dimensional image sensor (see Patent Document 1).
JP 2002-286425 A

  By the way, as described above, when detecting (measuring) the surface shape of an object to be measured based on an irradiation image by a two-dimensional imaging device, generally, the object to be measured is detected prior to the detection (measurement) of the surface shape. Therefore, complicated adjustment work such as positioning of the two-dimensional image sensor or the like is required so that the reflected light from the light is irradiated onto the two-dimensional image sensor.

  The present invention has been completed based on the above circumstances, and an object of the present invention is to provide a detection sensor capable of omitting an alignment operation of a two-dimensional imaging device or the like in the shape measurement. .

As means for achieving the above object, the detection sensor of the invention of claim 1 is a light projecting means for projecting light,
Two-dimensional imaging means having an imaging surface capable of receiving reflected light from the measurement object among the light projected from the light projecting means;
In a detection sensor comprising: a measuring unit that measures the measurement object based on a level of a light reception signal of light received by each pixel of the imaging surface of the two-dimensional imaging unit;
The area of the imaging surface of the two-dimensional imaging means is larger than the irradiable area where the reflected light from the measurement object in the measurement range can be irradiated to the imaging surface when the measurement object is measured. Configured,
Prior to measurement by the measurement unit, of the reference light projected from the light projection unit, measurement by the measurement unit based on a light receiving position received by the imaging surface of reflected light from the measurement object Pixel selection means for selecting a measurement use pixel to be used at the time of,
Storage means for storing information about the measurement use pixel selected by the pixel selection means,
The measurement means is characterized in that the measurement object is measured based on the level of the light reception signal of the measurement use pixel stored in the storage means.

According to a second aspect of the present invention, in the first aspect, the pixel selection unit includes:
Prior to measurement by the measurement means, the measurement use pixel is based on the light receiving position of the reflected light received by the imaging surface when the measurement object is moved to the upper limit position and the lower limit position of the measurement range. It has a feature in selecting.

According to a third aspect of the present invention, in the first aspect, the light projecting unit projects linear light onto the measurement object, and the measurement surface of the two-dimensional image capturing unit includes the measurement. The linear reflected light from the object is received,
The pixel in the region between the light receiving position of the imaging surface when the measurement object is at the upper limit position and the light receiving position of the imaging surface when the measurement object is at the lower limit position is used for the measurement. It is characterized in that it is selected as a pixel.
Note that the “region between the light receiving position of the imaging surface when the measurement object is at the upper limit position and the light receiving position of the imaging surface when the measurement object is at the lower limit position” includes both on the imaging surface. The light receiving position itself, that is, a linear portion is included.

  According to the shape measuring method of the invention of claim 4, prior to measurement of the measurement object, the reflected light is received by the reflected light from the measurement object in the measurement range among the light projected from the light projecting means. Information is received by the imaging surface of the two-dimensional imaging means having an imaging surface having a larger area than the range to be measured, and a measurement pixel to be used for measurement is selected based on the light receiving position on the imaging surface. Is stored in the storage means, and the measurement object is measured based on the level of the light reception signal of the measurement use pixel stored in the storage means.

<Invention of Claims 1 and 4>
When the reflected light from the measurement object is received by the pixels in a predetermined range, complicated work such as alignment of the two-dimensional imaging means is required.
On the other hand, according to this configuration, the measurement use pixel used in the measurement by the measurement unit is selected based on the actual light receiving position. Therefore, alignment work such as a two-dimensional imaging unit in the shape measurement can be omitted.

<Invention of Claim 2>
According to this configuration, prior to the measurement by the measurement means, the measurement use pixel is selected by actually irradiating the imaging surface with the reflected light from the measurement object. Can do.

<Invention of Claim 3>
According to this configuration, since the pixel in the region between the two light receiving positions of the linear reflected light received by the imaging surface is selected as the measurement use pixel, the measurement use pixel can be reliably selected with a simple configuration. Can do.

An embodiment of the present invention will be described with reference to FIGS.
1. 1 is a schematic configuration of a shape measuring apparatus 1 that can use the shape measuring method according to the present invention.
The shape measuring apparatus 1 includes a detection sensor 10 that detects the surface shape of the measurement target W, and a stage drive unit 30 that can move (lift up and down) a stage 31 on which the measurement target W is placed. It is configured.

  The detection sensor 10 passed through a light projecting section 11 (light projecting means) that projects laser light, a slit plate 12 that converts the laser light from the light projecting section 11 into a slit-shaped laser light L1, and a slit plate 12. A CMOS image sensor 13 (corresponding to the “two-dimensional imaging means” of the present invention) that receives the reflected light L2 reflected by the surface of the measurement object W placed on the stage 31 among the laser light L1; The control circuit 15 includes a CPU 14 (Central Processing Unit) and the like, and the storage unit 17 includes a RAM (Random Access Memory) in which information from the control circuit 15 is stored.

  The light projecting unit 11 includes a laser light source 11 </ b> A that emits laser light, and a light source driving circuit 11 </ b> B that causes the laser light source 11 </ b> A to perform a light projecting operation based on a light projection timing signal from the CPU 14 of the control circuit 15.

  The slit plate 12 has a slit (cut) extending long in the depth direction of FIG. 1 (Y-axis direction in FIG. 2), and a thin plate-like laser beam L1 that has passed through the slit of the slit plate 12 is a measurement object. Irradiation is directed toward the surface of W. Of the light irradiated to the measuring object W from the light projecting unit 11 via the slit plate 12, the reflected light L <b> 2 reflected by the surface of the measuring object W is received by the imaging surface 13 </ b> A of the CMOS image sensor 13. It has become so.

  That is, the irradiation image 16 formed on the imaging surface 13A of the two-dimensional CMOS image sensor 13 by the reflected light L2 is aligned with the slit shape of the slit plate 12 if the surface of the measuring object W is flat. Shape. On the other hand, as shown in FIG. 2, when the convex part is formed in the surface of the measuring object W, for example, it becomes the convex irradiation image 16 according to this convex part shape. Therefore, the surface shape of the measurement object W can be detected by capturing the irradiation image 16 on the imaging surface 13A of the two-dimensional CMOS image sensor 13.

  The CMOS image sensor 13 includes a large number of pixels 20, a vertical scanning shift register 25, and a horizontal scanning shift register 26 that form the imaging surface 13 </ b> A arranged in a matrix. The area of the imaging surface 13A of the CMOS image sensor 13 is such that the reflected light from the measuring object W is within the range of the imaging surface 13A even if the measuring object W is moved to the upper limit position and the lower limit position by the stage driving unit 30. It is supposed to fit in the area. In the following description, as briefly shown in FIG. 4, an example including three pixels 20 in total in the row direction and three in the column direction will be described.

  As shown in FIG. 4, the pixel 20 includes a photodiode 21 and an amplifier circuit 22 that amplifies the output from the photodiode 21. The amplifier circuit 22 is connected to MOS switches 23 (23A to 23I) and 24 (24A to 24C) for controlling on / off of the output from the amplifier circuit 22.

  For example, when a pulse signal is given in a predetermined cycle from the CPU 14 of the control circuit 15 to the vertical scanning shift register 25 when the MOS switch 24A is in the ON state, the vertical MOS switch 23A of the pixel 20 on one end side. To the vertical MOS switch 23C of the pixel 20 on the other end side in turn (ON / OFF is switched). When the vertical MOS switch 23 (vertical MOS switch 23C) for the pixels 20 in one column is turned on (when the pulse signals for the number of pixels in one column are supplied to the vertical scanning shift register 25), the pulse signal from the control circuit 15 is This is given to the horizontal scanning shift register 26, and this time, the horizontal MOS switch 24B of the pixel 20 at one end of the next column (next to one row) is turned on (turned on and off). The above operation is repeated until the output from all the pixels 20 is completed. Thus, the light reception signals Sa from all the pixels of the CMOS image sensor 13 are sequentially output to the control circuit 15 at a predetermined timing.

  As a result, each time a pulse signal is output from the CPU 14 to the vertical scanning shift register 25, the light receiving signal Sa of a level corresponding to the amount of received light is sequentially output from each pixel 20, so that the vertical scanning shift register 25 (and horizontal Depending on the timing of the pulse signal output to the scanning shift register 26) and the order of the light reception signal Sa for each pixel input to the control circuit 15, the CPU 14 receives the received light reception signal Sa from any pixel 20. Whether it is the light reception signal Sa is detected.

When the light projecting / receiving operation described above is performed before the shape measurement operation, the CPU 14 (shape measurement) outputs a pixel to which the light reception signal Sa (or a light reception signal having a light reception amount level equal to or greater than a predetermined threshold) is output. Information (position information) for specifying this pixel (measurement use pixel) is stored in the storage unit 17. Therefore, the CPU 14 corresponds to the “pixel selection unit” of the present invention.
When the light projecting / receiving operation described above is performed during the shape measuring operation, the CPU 14 receives the received light signal Sb from the pixel (measurement use pixel) selected before the shape measuring operation. In this case, the received light amount level (or whether a received light amount equal to or greater than a predetermined threshold value) is stored in the storage unit 17, and the CPU 14 measures the measurement object based on the received light amount level stored in the storage unit 17. The surface shape of W is measured. Therefore, the CPU 14 corresponds to the “measuring means” of the present invention.

  As shown in FIG. 1, the stage drive unit 30 is connected to the control circuit 15 of the detection sensor 10 via a communication means 35 such as a cable, and outputs from the control circuit 15. In response, the measuring object W can be moved to a desired height.

  Here, the stage drive unit 30 can move the measurement object W placed on the stage 31 between a predetermined upper limit position and a lower limit position. Then, when specifying (selecting) the measurement use pixel to be performed before the shape measurement, when the measurement target W is at the upper limit position, the light receiving position of the light received on the imaging surface 13A (the irradiation image in FIG. 3). 16A position) and the light receiving position (position of irradiated image 16B) of light received by imaging surface 13A when measurement object W is at the lower limit position. Based on the lower end position (lower end portion, dotted line B in the figure) and the widthwise ends of the irradiation image 16 (dotted lines C and D in the figure), the regions (between each end portion) surrounded by these regions Pixels within the range sandwiched between the pixels) is a measurement use pixel (measurement use range) used in the shape measurement on the imaging surface 13A.

  The “measurement range” of the measurement object W in the present invention is determined by the range in which the measurement object W is movable between the upper limit position and the lower limit position (the movable range of the stage drive unit 30). The “measurement range” is predetermined by the specification of the detection sensor. The position of the measurement object W between the upper limit position and the lower limit position can be set by the user via an operation unit (not shown).

2. Process Performed by CPU of Control Circuit (1) Process Performed Prior to Shape Measurement The following process is performed prior to the shape measurement of the measurement object W.
<Measurement use range identification process>
As shown in FIG. 5, the CPU 14 gives a drive signal to the stage drive unit 30 to drive it, and moves the stage 31 to the upper limit position (S11).
Then, a pixel selection process for selecting a pixel to be used for measurement is executed (S12).

(Pixel selection processing)
In the pixel selection process, as shown in FIG. 6, the CPU 14 outputs a light projection timing signal for causing the light source drive circuit 11B to project the light projecting unit 11 (S21). As a result, laser light (reference light) is emitted from the light projecting unit 11. When the laser light L2 reflected by the measurement object W is received by the CMOS image sensor 13, a light reception signal Sa corresponding to the amount of light received is output to the CPU.

When the CPU 14 detects that the light reception signal Sa has been received (“Y” in S22), the timing of the light projection timing signal (or the timing of the pulse signal output to the shift register) and the timing (or order) of the light reception signal Sa. Then, a pixel that outputs the light reception signal Sa is obtained (S23).
Information (position information, for example, coordinate data, light reception timing, etc.) specifying the obtained pixel is stored in the storage unit 17 (S24).

Next, in S <b> 13 of FIG. 5, the CPU 14 gives a drive signal to the stage drive unit 30 to drive it, and moves the stage 31 to the lower limit position.
Then, a pixel selection process for selecting a pixel to be used for measurement is executed (S14).

(Pixel selection processing)
In the pixel selection process, as shown in FIG. 6, the CPU 14 outputs a light projection timing signal for causing the light source drive circuit 11B to project the light projecting unit 11 (S21). As a result, laser light (reference light) is emitted from the light projecting unit 11. When the laser light L2 reflected by the measurement object W is received by the CMOS image sensor 13, a light reception signal Sa corresponding to the amount of light received is output to the CPU.

When the CPU 14 detects that the light reception signal Sa has been received (“Y” in S22), the timing of the light projection timing signal (or the timing of the pulse signal output to the shift register) and the timing (or order) of the light reception signal Sa. Then, a pixel that outputs the light reception signal Sa is obtained (S23).
Information (position information, for example, coordinate data, light reception timing, etc.) specifying the obtained pixel is stored in the storage unit 17 (S24).

  Next, in S15 of FIG. 5, the CPU 14 sets the upper end portion (dotted line A in FIG. 3) of the light receiving portion of the imaging surface 13A when the measurement target W is at the upper limit position and the measurement target W at the lower limit position. At the lower end of the light receiving portion of the imaging surface 13A at that time (dotted line B in the figure) and both side ends of the light receiving portion of the imaging surface 13A (dotted lines C and D in the figure, the width of the measuring object W). The enclosed area (including the boundary portion) is set as a measurement use range (measurement use pixel) used in the surface shape measurement (S15), and information on the measurement use range (measurement use pixel) is stored in the storage unit 17. (S16).

(2) Processing performed at the time of shape measurement The following processing is performed at the time of measuring the surface shape of the measurement object W.
As shown in FIG. 7, the CPU 14 outputs a light projection timing signal for causing the light source drive circuit 11B to project the light projecting unit 11 (S31). Thus, when the laser light is emitted from the light projecting unit 11 and the laser light reflected by the measurement object W is received by the CMOS image sensor 13, a light reception signal Sb corresponding to the amount of received light is output to the CPU 14.

  Next, when the CPU 14 detects that the light reception signal Sb is received from the CMOS image sensor 13 (“Y” in S32), information on the position of the measurement use pixel stored in the storage unit 17 (measurement use range of the measurement use range). Information) is read (S33), and it is determined whether or not the obtained light reception signal Sb is the light reception signal Sb from the measurement use pixel (measurement use range) (S34).

When the light reception signal Sb is the light reception signal Sb from the measurement use pixel (measurement use range) (“Y” in S34), the light reception signal Sb is stored in the storage unit 17.
On the other hand, when the light reception signal Sb is not the light reception signal Sb from the measurement use pixel (measurement use range) (“N” in S32), the obtained light reception signal Sb is deleted (deleted).
Then, the CPU 14 measures the surface shape of the measurement object W based on the light reception signal Sb stored in the storage unit 17.

3. Effects of the present embodiment (1) When the reflected light from the measurement object W is received by the pixels 20 in a predetermined range, complicated operations such as alignment of the CMOS image sensor (two-dimensional imaging means) are performed. I need it. Further, in the case where the positioning is not required by simply increasing the size of the CMOS image sensor, the control circuit 15 receives light reception signals from all the pixels of the CMOS image sensor during the shape measurement. Is remembered. Therefore, in order to store such a large amount of information, it is necessary to increase the capacity of the storage unit 17, which is not desirable from the viewpoint of manufacturing cost and the like. Furthermore, when light reception signals from all pixels (the entire imaging surface 13A) are received (light reception signals from pixels not required for measurement are also received), accurate shape measurement is not performed due to noise such as ambient light. There is a fear.

  On the other hand, according to the present embodiment, the area of the imaging surface 13A of the CMOS image sensor 13 (two-dimensional imaging means) is reflected from the measurement object W in the measurement range when the measurement object W is measured. It is configured to be larger than the irradiable area (region surrounded by dotted lines A, B, C, and D in FIG. 3) where light can be irradiated onto the imaging surface 13A, and is projected prior to measurement by the CPU 14 (measurement means). In the measurement by the CPU 14 (measurement means) based on the light receiving position where the reflected light from the measurement object W is received by the imaging surface 13A among the reference light projected from the means (light projection unit 11). The measurement use pixel 20 to be used is selected and stored in the storage unit 17 (storage means). At the time of measurement by the CPU 14 (measuring means), the level of the light reception signal Sa of the measurement use pixel 20 selected based on the light reception position confirmed by actually performing the light projecting / receiving operation as described above is set. Based on this, the measurement object W is measured. Thereby, work such as alignment of the CMOS image sensor 13 (two-dimensional imaging means) can be omitted, and workability can be improved.

  (2) The light reception position of the imaging surface 13A when the measurement object W is at the upper limit position, the light reception position of the imaging surface 13A when the measurement object W is at the lower limit position, and the range in the width direction of the irradiation image 16 Based on the above, the area surrounded by these areas (pixels in the range between these upper, lower, left and right positions) is the measurement use pixel (measurement use range) used in the shape measurement on the imaging surface 13A. ). Therefore, it is possible to reliably select the measurement use pixel with a simple configuration in which the measurement object W is moved to the movable upper limit position and the lower limit position.

<Other embodiments>
The present invention is not limited to the embodiments described with reference to the above description and drawings. For example, the following embodiments are also included in the technical scope of the present invention, and further, within the scope not departing from the gist of the invention other than the following. Various modifications can be made.

(1) In the above embodiment, the two-dimensional imaging unit of the present invention is configured by the CMOS image sensor 13, but the two-dimensional imaging unit may be configured by a CCD (Charge Coupled Devices). In addition, the CCD transmits the signal of each pixel sequentially next to each other and is amplified at the end of each column (bucket relay system), so that noise is not easily generated during signal transmission, and at the end of each column. Since it is amplified, there is an advantage that there is little variation due to the amplifier circuit.
On the other hand, if a CMOS image sensor is used as in this embodiment, power consumption can be reduced compared to a CCD. Furthermore, since the CMOS process is applied, it becomes easy to integrate other circuits (A-D converter, etc.).

  (2) In the above embodiment, among the imaging surface 13A, the light receiving position of the imaging surface when the measurement object W is at the upper limit position, and the light reception position of the imaging surface when the measurement object W is at the lower limit position; The pixels in the area between are used as the measurement use pixel range (measurement use range), but it is not always necessary to set only the pixels within such a range as the measurement use pixel (measurement use range). If it is in the vicinity, a pixel outside the boundary of the light receiving position (external region) may be used as a measurement use pixel (measurement use range).

The figure which shows the structure of the shape measuring apparatus 1 schematically The figure which shows a mode that the laser beam reflected by the measuring object W is irradiated to a CMOS image sensor The figure which shows the irradiation image of the imaging surface of a CMOS image sensor The figure explaining the structure of a CMOS image sensor Flowchart of CPU processing performed before shape measurement Pixel selection process flowchart Flowchart of CPU processing during shape measurement

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Shape measuring apparatus 10 ... Detection sensor 11 ... Light projection part (light projection means)
13 ... CMOS image sensor (two-dimensional imaging means)
13A ... Imaging surface 14 ... CPU (measuring means, pixel selecting means)
15 ... Control circuit 17 ... Storage section (storage means)
20 ... Pixel 30 ... Stage driver L1 ... Laser light L2 ... Reflected light W ... Measurement object

Claims (4)

A light projecting means for projecting light;
Two-dimensional imaging means having an imaging surface capable of receiving reflected light from the measurement object among the light projected from the light projecting means;
In a detection sensor comprising: a measuring unit that measures the measurement object based on a level of a light reception signal of light received by each pixel of the imaging surface of the two-dimensional imaging unit;
The area of the imaging surface of the two-dimensional imaging means is larger than the irradiable area where the reflected light from the measurement object in the measurement range can be irradiated to the imaging surface when the measurement object is measured. Configured,
Prior to measurement by the measurement unit, of the reference light projected from the light projection unit, measurement by the measurement unit based on a light receiving position received by the imaging surface of reflected light from the measurement object Pixel selection means for selecting a measurement use pixel to be used at the time of,
Storage means for storing information about the measurement use pixel selected by the pixel selection means,
The measurement means measures the measurement object based on a level of a light reception signal of the measurement use pixel stored in the storage means. The pixel selection means includes
Prior to measurement by the measurement means, the measurement use pixel is based on the light receiving position of the reflected light received by the imaging surface when the measurement object is moved to the upper limit position and the lower limit position of the measurement range. The detection sensor according to claim 1, wherein the detection sensor is selected. The light projecting means projects linear light onto the measurement object, and linear reflected light from the measurement object is received on the imaging surface of the two-dimensional imaging means. ,
The pixel in the region between the light receiving position of the imaging surface when the measurement object is at the upper limit position and the light receiving position of the imaging surface when the measurement object is at the lower limit position is used for the measurement. The detection sensor according to claim 2, wherein the detection sensor is selected as a pixel. Prior to the measurement of the measurement object, the reflected light from the measurement object in the measurement range out of the light projected from the light projecting means has an imaging surface with a larger area than the range in which the reflected light is received. The two-dimensional imaging unit having the imaging surface receives light, selects a measurement use pixel to be used for measurement based on the light receiving position on the imaging surface, stores information on the measurement use pixel in the storage unit, and stores the information in the storage unit. A shape measuring method, comprising: measuring the measurement object based on a stored light reception signal level of the pixel to be used for measurement.

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