KR100728483B1 - Displacement measuring method and displacement sensor - Google Patents

Abstract

The present invention is to provide a displacement sensor capable of always measuring the surface of the transparent body, regardless of the difference between the reflectance between the surface and the back surface of the transparent body, and in a solution for achieving the above object, a line toward a predetermined measurement target area. A projection means for irradiating a beam, a two-dimensional imaging device for imaging the measurement target area from an angle different from the irradiation angle of a line beam, and a displacement of an object in the measurement target area based on an output of the two-dimensional imaging device 1 or 2 included in the measurement target area based on the measurement means, the measurement target area setting means capable of setting two or more measurement target areas in the field of view of the two-dimensional imaging element, and the image photographed by the two-dimensional imaging element. Measurement point coordinate determining means for determining the measurement point coordinates described above, and the variation of the measurement displacement with respect to the reference plane of the measurement object. Disclosed is a displacement sensor provided with a zone automatic tracking means for following the same and moving at least one measurement target region end in the displacement measurement direction.

Displacement measurement method, displacement sensor

Description

Displacement measurement method and displacement sensor {DISPLACEMENT MEASURING METHOD AND DISPLACEMENT SENSOR}

1 is an external perspective view of a signal processor;

2 is an external perspective view of the signal processor in a continuous mounting state.

3 is an external perspective view of a sensor head.

4 is a block diagram showing the electrical hardware configuration of the signal processing unit.

5 is a block diagram showing the electrical hardware configuration of the sensor head portion.

6 shows a gap measurement between a photomask and a glass substrate.

7 is an example of a gap measurement by a displacement sensor to which the present invention is applied.

8 is an example of a gap measurement by a conventional displacement sensor.

9 is a general flow chart showing a procedure for determining a measurement area in a displacement sensor to which the present invention is applied.

FIG. 10 is a flowchart showing in detail the step 905 area provisional processing of FIG. 9; FIG.

FIG. 11 is a flowchart showing details of the step 908 area reset process of FIG. 9; FIG.

12 is an explanatory diagram of an area setting processing procedure;

13 is a timing chart showing a sensitivity adjustment process for each region.

Fig. 14 is a timing chart showing a process of following a set area with the up and down variation of a measurement point.

15 is a block diagram schematically showing an internal configuration of a controller of a displacement sensor to which the present invention is applied.

16 is an example of screen display (part 1) when setting the thickness of a glass substrate.

17 is an example of screen display at the time of setting the thickness of the glass substrate (No. 2).

18 is an example of screen display when setting the thickness of a glass substrate (No. 3).

19 is an example of a screen configuration of a displacement sensor to which the present invention is applied.

<Description of the code>

1: signal processing unit

2: sensor head

3: relay connector

4: D1N rail

5: Object to be detected

10: outer case

11: external connection cord

12: USB connector

13: RS-232C connector

14: control panel cover

15: display unit

16: connector cover between signal processing unit

17: connector for connecting the sensor head

20: sensor head body

21: cable

27: connector for signal processing unit

101: control unit

102: memory

102a: nonvolatile memory

102b: Picture memory

103: display unit

103a: liquid crystal display

103b: Indicator LED

104: communication unit with the sensor head

105: communication unit with an external device

105a: USB communication unit

105b: serial communication unit

105c: communication unit between signal processing units

106: key input unit

107: external input unit

108: output unit

109: power supply

110: external personal computer

201: control unit

202: floodlight

203: light receiver

204: Indicator LED

205: memory

206: communication unit

61: sensor head

62: photo mask

63: glass substrate

63a: expected movement position of the glass substrate

71: The image behind the photo mask

72: deposit on the surface of the glass substrate

73: deposit on the back of the glass substrate

81: The image behind the photo mask

82: deposit on the surface of the glass substrate

83: A deposit on the back surface of the glass substrate

1501: sensor head

1502: controller

1503: A / D Converter

1504: region determination unit

1505: picture memory

1506: display synthesis unit

1507: D / A Converter

1508: displacement, concentration extraction unit

1509: console interface

1510: External I / O Interface

1511: memory

1512: CPU

1513: area setting unit

1514: calculating unit

1515: sensitivity determination unit

1601: deposits on the surface of the transparent body

1602: the deposit on the back of the transparent body

603: cursor

1901: Area (0)

1902: Area (1)

1903: The image behind the photo mask

1904: deposits on the surface of the glass substrate

1905: Line bright display behind the photo mask

1906: Line bright display of the glass substrate surface

1907: light-receiving sensitivity of the area (0) and the peak value of the optical image in the area (0)

1908: light reception sensitivity of the area 1 and the peak value of the light image in the area 1

LI: irradiation deposit

L2: reflected light

L3: Reflected light from behind the photo mask

L4: reflected light from the glass substrate surface

P1: peak of reflected light on the glass substrate surface

P2: Peak of reflected light behind a glass substrate

Field of technology

BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a displacement sensor, and in particular, a displacement sensor suitable for gap measurement between a glass substrate used for a flat panel display (hereinafter referred to as FPD) and a photo mask used for exposure processing on the glass substrate. It is about.

Prior art

The displacement sensor is roughly divided into a one-dimensional displacement sensor and a two-dimensional displacement sensor. The former uses the spot beam as the measurement medium, and the latter uses the line beam as the measurement medium. Only the latter is mainstream these days.

More specifically, in the two-dimensional displacement sensor, light emitted from a light source such as a laser diode is used as a line beam by using a slit, and this is irradiated to the measurement object. Thereby, the irradiation light image according to the surface shape or a characteristic is projected on the measurement object object (regardless of visibility). That is, for example, when the surface of the measurement object (the transparent surface is also included in the case of the transparent object) is a flat surface without irregularities, a straight irradiation light image corresponding to the line beam appears on the surface of the measurement object. On the other hand, when unevenness | corrugation etc. exist in the irradiation area of a line beam, a nonlinear irradiation light image appears. Therefore, the irradiation light image appearing on the surface of the object to be measured is imaged by a two-dimensional imaging device, and the light receiving area (coordinate) of the two-dimensional imaging device is detected, thereby the distance from the light source to the measurement object and the surface of the measurement object. It is possible to measure various values such as the properties, the amount of displacement, or the thickness.

One use of such a two-dimensional displacement sensor includes gap measurement between a glass substrate used for FPD and a photomask made of glass used when performing exposure treatment on the glass substrate. In performing the exposure treatment, a plurality of displacement sensors are arranged on the same plane so that the glass substrate and the photo mask are parallel, and at a plurality of points so that the gap between the photo mask and the glass substrate is settled in a predetermined numerical range. Gap measurement is performed. The glass substrate to which an exposure process is performed differs for each board | substrate, such as the thickness of a board | substrate and the kind of resist liquid apply | coated to the surface, and the intensity | strength of the reflected light also differs for every board | substrate. Therefore, in the two-dimensional displacement sensor used for the gap measurement of the glass substrate used for FPD and the glass photomask used at the time of performing an exposure process to a glass substrate, the light reception sensitivity adjustment of the measurement area | region has acquired the optical image. It is usually done automatically for each area so that it can be measured with an appropriate sensitivity. When automatic sensitivity adjustment is performed, the sensitivity is adjusted so as to be suitable for measuring the optical image in the case where there is only one optical image in the area, and the optical image having the largest amount of received light when the plurality of optical images are in the area, or the image that satisfies any condition. The light receiving sensitivity is adjusted on the basis of.

As a displacement sensor used for this kind of use, the applicant proposes the displacement sensor described previously in International Publication No. 01/57471 (Patent Document 1). The displacement sensor described in Patent Document 1 is characterized in that the user can arbitrarily designate a light-receiving presence / absence detection subject region (actual measurement region) in the two-dimensional imaging element. In this displacement sensor, the approximate light receiving area is predicted in advance to limit the actual measurement area in the two-dimensional imaging device, thereby eliminating the need for detection processing for areas other than the actual measurement area. The remarkable effect that the response speed is greatly improved is obtained.

Patent Document 1: International Publication No. 01/57471 Pamphlet

However, even in the above-mentioned displacement sensor, the light receiving sensitivity adjustment of each measurement area is generally performed automatically for each area. When a plurality of light images are detected in one area, the light receiving sensitivity is adjusted based on the light image having the largest light receiving amount. There is a fear that the desired optical image may not be detected.

For example, when both the light image (small light receiving amount) on the glass substrate surface and the light image (large light receiving amount) on the back surface of the glass substrate are included in the area for measuring the light image of the glass substrate, the light receiving sensitivity of this area is the light receiving amount on the back surface of the glass substrate. It is usually adjusted on the basis of. If there is a large difference between the light-receiving amount of the glass substrate surface optical image and the light-receiving amount of the glass substrate backside optical image here, the light-receiving amount of the glass substrate surface optical image may be too small to be detectable as a result of sensitivity adjustment based on the glass substrate backside optical image. In this case, the glass substrate surface optical image required for gap measurement is not measured, and instead, the optical image on the back surface of the glass substrate in the area is mistakenly recognized as a surface optical image. Since the thickness of the glass substrate is much larger than the gap (ΔG) between the photomask and the glass substrate during the exposure treatment, if the glass substrate surface image and the back image are taken incorrectly, the glass substrate may approach the photomask. The accident of contact can happen.

As a solution to such a problem, in a region for measuring an optical image of a glass substrate, a method of recognizing the optical image closest to the photomask among the optical images included in the region as a measurement target and setting the other optical image so as not to be a detection target is considered. do. However, in such a case, in the case of the substrate in which the optical image under the photomask is not detected, it is impossible to specify the optical image "closest to the photomask", which causes a problem in measurement.

Moreover, although the said patent document 1 has described the displacement sensor which follows the image of the reflecting surface and moves the measurement object area | region itself, when the 2 or more measurement object area | region is provided, the area | region which does not move and the area | region which move are mixed If they do, the above-mentioned problems arise when these areas overlap each other.

This invention is made | formed in view of the said problem, The objective is to provide the displacement sensor which can always measure the surface of a transparent body, regardless of the difference of the reflectance of the surface of a transparent body and the back surface.

Still other objects and effects of the present invention will be readily understood by those skilled in the art from the following description of the specification.

In order to achieve the above object,

According to the displacement measuring method of the present invention, one surface of the first transparent plate is fixed and arranged to be included in the measurement target area, and the second transparent plate is approached from a position away from the predetermined distance by opposing the surface. And a reflection surface for irradiating a beam toward the measurement target region, imaging the measurement target region with an imaging device from an angle different from the irradiation angle of the beam, and reflecting the beam of the first transparent plate and the second transparency. A method of measuring a displacement based on an optical image of a reflecting surface that reflects the beam of a plate, wherein, prior to measurement of the displacement, one surface of the first transparent plate is placed in the field of view of the imaging device in the first measurement target region. Is set in a range in which the optical image of the reflective surface can be picked up, and the second measurement target region is located at a position away from the predetermined distance at which the second transparent plate is opposed to the one surface described above. In a state, it does not contain the optical image of the reflecting surface by the surface of the side which is far from the 1st transparent plate of a 2nd transparent plate, and it sets in the range which does not overlap with a 1st measurement object area | region, In the measurement, the second transparent plate is irradiated toward the measurement target area while the second transparent plate is approached from a position separated by a distance or more away from the reflective surface of the first transparent plate, and the image is repeatedly imaged by the imaging device. With respect to the second measurement target area, the position of the end on the side opposite to the first measurement target area with respect to the alignment direction of the optical image of the reflective surfaces in the first and second measurement target areas, Based on the optical image of the reflecting surface existing in the second measurement target area, the following is performed so as to be within a predetermined range, and the sensitivity of the first and second measurement target areas is the most received amount in each measurement target area. The measurement point coordinates are respectively determined from the light image of the reflecting surface of the object present in each measurement target region obtained by automatic adjustment based on the amount of light received on the reflecting surface or on the reflecting surface selected under predetermined conditions. Based on the determined measurement point coordinates, the displacement of the reflection surface in the first measurement object region and the displacement of the reflection surface of the second measurement object region are measured.

The predetermined condition refers to a predetermined condition for selecting a reflection surface existing in the measurement target region, which is commonly used for displacement measurement performed during the operation of bringing the second reflection plate close to the first reflection plate once.

Further, a gap for calculating the distance between the first transparent plate and the second transparent plate can be measured from the displacement of the reflective surface in the first measurement target region and the displacement of the reflective surface of the second measurement target region. Can be.

According to such a method, it is possible to measure the displacement of the reflecting surface of the transparent plate or the gap between the transparent plates to approach the fixed transparent plate, regardless of the difference in reflectance between the front and rear surfaces of the transparent body.

Preferably, the alignment direction of the optical image of the reflective surface in the first and second measurement target regions is within a constant range based on the optical image of the reflective surface existing in the region, which follows the end of the second measurement target region. Regarding this, it is larger than the width of the optical image of the reflection surface and smaller than the interval in the field of view of the imaging device corresponding to the thickness of the second transparent plate.

According to this method, the displacement can be measured stably with respect to one surface of the moving second transparent body.

Preferably, the second transparent plate is brought out of the field of view of the imaging device.

According to this method, since two surfaces of the second transparent plate do not exist from the beginning in the second measurement target area, there is a risk that the measurement target area is wrongly set on the side of the second transparent plate. Disappear.

Preferably, the beam is a line beam. The second transparent plate is a glass substrate used for an FPD (flat panel display), and the first transparent plate is a mask glass used for an exposure process.

The displacement sensor of the present invention is based on projection means for irradiating a beam toward a predetermined measurement target region, an imaging element for imaging the measurement target region from an angle different from the irradiation angle of the beam, and measurement based on the output of the imaging element. Measurement means for measuring the displacement of an object in the target area, measurement target area setting means capable of setting two or more measurement target areas in the field of view of the imaging device, and a set measurement target area based on an image captured by the imaging device. Measurement point coordinate determining means for determining one or two or more measurement point coordinates to be included, and a measurement including a reflection surface of the measurement object in which the measurement displacement fluctuates following a change in measurement displacement with respect to the reflection surface of the measurement object. Automatically adds an area to move one end of the measurement target area in the target area in the direction of change of the measurement displacement. A measuring means region having at least a first measuring object region and a second measuring object interpreter, and setting the first measuring object region with respect to a reflecting surface which is fixed and exists in the field of view of the imaging device; For the reflective surface of the measurement target object in which the measurement displacement fluctuates, the second measurement target curve is set in a range other than the first measurement target region so as to include the reflection surface, and the area automatic tracking means is the first. And the end of the second measurement target region on the side opposite to the first measurement target region with respect to the alignment direction of the optical image of the reflecting surface in the second measurement target region.

According to such a structure, it is possible to provide the displacement sensor which can measure the reflecting surface of the transparent plate which approaches a fixed transparent plate, regardless of the difference of the reflectance between the front surface and the back surface of a transparent body.

Preferably, the 2nd measurement object area | region sets one edge part of the direction of the measurement displacement in the visual field of an imaging element as an end.

Moreover, Preferably, the coordinate of the edge part on the side of a 1st measurement object area | region in the direction of the measurement displacement in the visual field of the imaging element of a 2nd measurement object area | region is made into the measurement point coordinate of the image contained in a 1st measurement object area | region. When setting based on it, and the coordinate of the edge part on the opposite side to the 1st measuring object area | region in the direction of the measurement displacement in the visual field of the imaging element of a 2nd measuring object area | region is not included in a 2nd measuring object area | region In this case, one end in the direction of the measurement displacement in the field of view of the imaging element is set as the terminal, and when the image is included in the second measurement target region, the measurement point coordinates of the image included in the second measurement target region. Set the termination according to.

According to such a configuration, by configuring the first measurement target region for the image included in the initial state, it is possible to automatically generate the first measurement region even if the operator does not perform any special operation, and the operation is simpler. Done. Moreover, when measuring a transparent body in a 2nd measurement object area | region, it becomes possible to reliably put in single side | surface one side to a measurement area | region.

According to such a structure, even if a reflective surface is not contained in a 2nd measurement area, it becomes possible to temporarily set a 2nd measurement area based on the image in a 1st measurement area. In addition, when the reflecting surface is included in the second measurement area, the end point coordinates are set based on the image in the second measurement area, so that the coordinates based on the state can be set more.

Preferably, when the displacement of the reflecting surface contained in the 2nd measurement object area | region is measured, the coordinate of the end point of a 2nd measurement object area | region is based on the measurement point coordinate of the reflecting surface contained in a 2nd measurement object area | region. Reset.

According to such a structure, since the 2nd measurement area | region end coordinate is changed suitably according to the displacement of the image in a 2nd measurement area | region, it becomes possible to set the area according to a situation even when a reflective surface moves.

Preferably, when the image is included in the second measurement target region, the image is set based on the coordinates of the measurement point of the image included in the second measurement target region, or the image included in the second measurement target region. The distance from the measurement point coordinates of the 2nd measurement object area | region which resets the coordinates of a 2nd measurement object area | region end point based on a measurement point coordinate to a terminal is smaller than the thickness of a glass substrate.

By this method, only a glass substrate surface can be measured always, and the abnormality by measuring a glass substrate back surface does not arise.

Preferably, it can utilize suitably for the measurement of the gap of the glass substrate used for FPD (flat panel display), and the mask glass used for the exposure process with respect to a glass substrate. The beam may be a line beam.

As is apparent from the above configuration, according to the present invention, since the end point of the measurement target region is determined by the measurement point coordinates in the measurement target region, the displacement sensor capable of always measuring the surface of the transparent body regardless of the difference in reflectance between the front surface and the rear surface of the transparent body It is possible to provide.

EMBODIMENT OF THE INVENTION Below, preferred embodiment of the displacement sensor of this invention is described in detail, referring an accompanying drawing. In addition, embodiment described below is only an example of this invention, The point made into the summary of this invention is prescribed only by description of a claim.

The displacement sensor of the present embodiment is a so-called amplifier-displacement type displacement sensor in which a signal processing unit and a sensor head unit are separated in order to enable compact accommodation in a control panel or the like and to facilitate installation in a narrow measurement environment.

The external perspective view of the signal processing part of the displacement sensor of this embodiment is shown in FIG. The outer case 10 of the signal processing unit 1 has a form of a slightly elongated rectangular parallelepiped. The external connection cord 11 is pulled out from the front surface of the outer case 10. The external connection cord 11 includes an external input line, an external output line, a power supply line, and the like. The external input line is for externally giving various commands to the signal processing unit 1 from, for example, a programmable logic controller (PLC) as the host device, and the external output line is a switching generated inside the signal processing unit 1. The output line or analogue output is for outputting to a PLC or the like, and the power supply line is for supplying power to the internal circuit of the signal processing section. In addition, the front surface of the outer case 10 is provided with a USB connector 12 and an RS-232C connector 13.

The operation part cover 14 which can be opened and closed is provided in the upper surface of the outer case 10. Although not shown, an operation unit for performing various command operations and the like in the signal processing unit 1 is provided under the operation unit cover 14. Moreover, the display part 15 for performing operation display etc. is arrange | positioned at the upper surface of the outer case 10. As shown in FIG.

Connector covers 16 are provided between the signal processing sections on the left and right sides of the outer case 10. Inside the connector cover 16 between the signal processing sections, a connector (relay connector 3) between the signal processing sections for connecting the other signal processing section 1 is provided.

The external perspective which shows the continuous mounting state of several signal processing part 1 is shown in FIG. As shown in the figure, the plurality of signal processing units 1 are continuously mounted in one row in the adjacent coupling state using the DL rail 4 in this example. On the rear surface of the outer case 10 of the signal processing unit 1, a connector 17 for connecting a sensor head portion is provided. The signal processing section 1 is connected to the sensor head section 2 described later through this sensor head section connecting connector 17.

An external perspective view of the sensor head is shown in FIG. 3. The sensor head portion 2 includes a signal processing portion connection connector 27 corresponding to the sensor head connection connector 17, a cable 21, and a sensor head main body portion 20. The pulsed laser light emitted from the light transmitting element (laser diode in this example) built into the main body 20 is slit light L1 on the surface of the measurement target object 5 through a light transmitting lens (not shown). Is investigated. As a result, the irradiation light image LI of the slit light is formed on the surface of the measurement object 5. The reflected light L2 of the slit light reflected by the measurement target object 5 is received by a two-dimensional imaging device (CCD type, CMOS type, etc.) through a light receiving lens (not shown) in the sensor head portion 2. That is, the image signal containing the irradiation light image LI of slit light is acquired by image | photographing the surface of the measurement object 5 by a 2D imaging element. Based on this video signal, a predetermined feature amount is extracted and a target displacement amount (in this example, the distance between the sensor head portion 2 and the measurement target object 5) is obtained.

A block diagram showing the entire electrical hardware configuration of the signal processing section 1 of the displacement sensor is shown in FIG. As shown in the figure, the signal processing unit 1 includes a control unit 101, a storage unit 102, a display unit 103, a communication unit 104 with a sensor head unit, and a communication unit with an external device. 105, a key input unit 106, an external input unit 107, an output unit 108, and a power supply unit 109 are provided.

The control unit 101 is constituted by a central processing unit (CPU) and a field programmable gate array (FPGA), and is responsible for overall control of the signal processing unit 1 as a whole. The control unit 101 realizes various functions to be described later, binarizes the received signal on the basis of a predetermined threshold value, and then outputs it as output data from the output unit 108 to the outside. The storage unit 102 includes a nonvolatile memory (EEPROM) 102a and an image memory 102b that stores image data displayed on the display unit 103. The display unit 103 displays a liquid crystal display 103a in which various values such as a threshold value and a distance to the measurement object are displayed, and an indicator LED 103b indicating an output state (on / off state) or the like corresponding to the measured value. Equipped. The communication unit 104 is in charge of communication with the sensor head unit 2. The external communication unit 105 includes a USB communication unit l05a for connecting to an external personal computer (PC) 110, a serial communication unit 105b for transmitting and receiving various commands and program data, a predetermined protocol and A signal processing unit 105c is provided between the signal processing units for performing data communication between adjacent left and right signal processing units in accordance with the transmission and reception format. The key input unit 106 is composed of switches, operation buttons, and the like for various settings (not shown). The external input unit 107 is for receiving various commands to the signal processing unit 1 from, for example, a host device such as a PLC. The output unit 108 is used to output the on / off output to a host device such as a PLC. The power supply unit 109 supplies power to the control unit 101 and external hardware circuits.

A block diagram showing the electrical hardware configuration of the sensor head 2 is shown in FIG. As shown in the figure, the sensor head unit 2 includes a control unit 201, a light projecting unit 202 for irradiating slit light toward the measurement target object 5, and a measurement target object 5. The light receiving unit 203, the indicator LED 204, the storage unit 205, and the communication unit 206 are provided for receiving the reflected light reflected by the light.

The control unit 201 is constituted by a central processing unit (CPU) and a programmable logic device (PLD), and serves to collectively control the respective components 202 to 206 of the sensor head unit.

In this example, the light projecting section 202 includes a laser diode as a light transmitting element and a light transmitting circuit, and emits slit light toward the detection target region. The light receiving unit 203 amplifies a light receiving signal obtained from the two-dimensional imaging device in synchronization with a two-dimensional imaging device (CCD type, CMOS type, etc.) that receives the reflected light of the slit light, and a timing control signal from the control unit 201. It has a light reception signal processing part output to the control part 201. The indicator LED 204 is turned on in response to various operation states of the sensor head 2. The storage unit 205 is constituted of, for example, a nonvolatile memory (EEPROM). In this example, an ID (identification information) or the like for classifying the sensor head unit 2 is recorded. The communication unit 206 is in charge of communication with the signal processing unit 1 in response to a command from the control unit 201. The sensor head 2 of the present embodiment has the circuit configuration as described above, and performs the appropriate light-receiving processing in response to the command of the signal processing section 1.

An example schematically showing the gap measurement between the photomask and the glass substrate in the displacement sensor to which the present invention is applied is shown in FIG. 6. In the figure, 61 is the sensor head portion of the displacement sensor, 62 is the photo mask, 63 is the glass substrate, 63a is the position to be moved of the glass substrate, L3 is the reflected light from the back side of the photo mask 62, and L4 is from the surface of the glass substrate. Reflected light, ΔG is a gap between the photomask 62 and the glass substrate 63. The photomask 62 has an exposure pattern drawn on the rear surface (surface on the side opposite to the glass substrate 63), and the photomask 62 is exposed to the glass substrate 63 from the photomask 62 surface side by an exposure apparatus (not shown). When not shown) When an exposure process is performed, the exposure pattern corresponding to each glass substrate is used. On the other hand, the resist liquid is apply | coated to the surface (surface of the side which opposes a photomask), and the exposure process is performed over the photomask 62, and according to the pattern on the back surface of the photomask 62, The glass substrate 63 is exposed. In this example, a plurality of displacement sensors may be used depending on the size of the glass substrate 63 or the like, so that the gap between the photomask 62 and the glass substrate 63 may be measured at a plurality of locations. In this case, what is necessary is just to set so that the exposure process may be performed, when the gap of all locations is settled in a predetermined range so that the glass substrate 63 and the photomask 62 may approach at regular intervals.

In this example, in the initial state before the measurement started, the photomask 62 enters the measurement area of the displacement sensor, but the glass substrate 63 is outside the measurement area of the displacement sensor. If the measurement starts, the glass substrate 63 moves in a direction approaching the photo mask 62 from outside the measurement area of the displacement sensor, approaches a distance of a predetermined gap ΔG, and the glass over the photo mask 62. An exposure treatment is performed on the substrate 63.

An example of the case where the gap between the photomask and the glass substrate is measured by a conventional displacement sensor is shown in FIG. 8. In the figure, area 0 is the area for measuring the photomask, area 1 is the area for measuring the glass substrate, 81 is the light image on the back of the photo mask, 82 is the light image on the surface of the glass substrate, and 83 is the A light image, P1, is a peak of reflected light on the glass substrate surface, and P2 is a peak of reflected light on the glass substrate back surface. In addition, the height of P1 and P2 has shown the intensity of each reflected light. In this example, the two optical images of the glass substrate surface optical image 82 and the glass substrate back surface optical image 83 enter the area 1, and the glass substrate back surface reflected light is higher in intensity than the glass substrate surface reflected light. As described above, in the case of a plurality of optical images in the area, it is common to automatically adjust the sensitivity based on the optical image having the highest intensity in the area. Therefore, in this example, since P1 < P2, the light receiving sensitivity of the area 1 is automatically adjusted based on the optical image 83 on the back surface of the glass substrate. In the case where a plurality of peaks are included in one area as described above, if there is a large difference in the intensity of the plurality of peaks, if the reception sensitivity is determined based on one peak, another peak may not be detected or may be saturated. . That is, in such a conventional displacement sensor, in the gap measurement between a photomask and a glass substrate, when the peak of a glass substrate surface << peak of the back surface of a glass substrate, the peak of a glass substrate surface is not detected, As a result, a photo Trouble may occur that the mask and the glass substrate are brought into close contact with each other.

Explanatory drawing of the detection area terminal automatic tracking in the case of performing the gap measurement of a photomask and a glass substrate with the displacement sensor to which this invention was applied is shown in FIG. In the figure, area 0 is an area for measuring a photomask, area 1 is an area for measuring a glass substrate, 71 is an image on the back of the photo mask, 72 is an image on the glass substrate surface, 73 is an image on the back of the glass substrate. , ΔG1 to ΔG3 are the distance between the photomask back surface and the glass substrate surface, ΔE is the distance from the glass substrate surface to the end of the area 1, ΔD is the thickness of the glass substrate, ΔZ is from the glass substrate surface It is a value smaller than ΔD as a predetermined distance. In this example, the position of the photomask of the area 0 does not move in any of FIGS. 7A to 7C, and the optical image 71 behind the photomask does not move. On the other hand, the position of the glass substrate of the area | region 1 is moving in the direction approaching a photomask in order with (a), (b), (c), and the distance between photomask and a glass substrate ((triangle | delta) G1-(triangle | delta) G3 ) Is a relationship of? G1>? G2>? G3.

First, in FIG. 7A, the glass substrate surface optical image 72 is immediately after entering the area 1 from the end side (in the figure, the right end side of the area 1). It is preferable to set the area 1 to some extent in an initial state so that it may be easy to catch a glass substrate surface optical image. The area width of the area 1 may be appropriately set in consideration of the thickness of the glass substrate and the like, but it is necessary that the area of the glass substrate surface optical image 72 does not enter the area 1 in the initial state. The glass substrate surface is outside the area of the area 1 at the start point of measurement and enters the area 1 from the end side. At this time, the distance ΔE between the glass substrate surface optical image 72 and the end point of the area 1 is smaller than the predetermined value ΔZ, that is, ΔE <ΔZ. In a step where the distance ΔE between the glass substrate surface optical image 72 and the end point of the area 1 is smaller than the predetermined value ΔZ, the end point may not be adjusted, and the area ( 1) may be widened. In the state immediately after the glass substrate surface optical image 72 entered the area 1, the glass substrate back surface optical image 73 is outside the area 1 of the area 1.

Subsequently, in FIG. 7B, the glass substrate is closer to the photomask than the viewpoint of FIG. 7A, and the distance ΔE between the glass substrate surface optical image 72 and the end point of the area 1 is ΔZ. It is. At the point of time DELTA E≥ΔZ, the end point E of the area 1 moves following the glass substrate surface optical image 72 such that DELTA E = ΔZ. Since ΔZ is a fixed value smaller than the thickness ΔD of the glass substrate, as long as the distance ΔE between the glass substrate surface optical image 72 and the area end point is smaller than ΔZ (that is, ΔE ≦ ΔZ) In the case of ΔD> ΔZ and ΔZ≥ΔE, the relationship of ΔD> ΔZ≥ΔE is always established, and the distance between the glass substrate surface optical image 72 and the end point of the area 1 (Δ). E) is always smaller than the thickness ΔD of the glass substrate, and the optical image 73 on the back surface of the glass substrate is outside the area of the area 1.

In Fig. 7 (c), the glass substrate is closer to the photo mask side than the viewpoint of Fig. 7 (b), but the end point E is glass so as to be a point away from the glass substrate surface optical image 72 by a fixed value? Z. Since following the substrate backside optical image 72, ΔE = ΔZ is always maintained, and the glass substrate backside image 73 always goes out of the area 1 and is not measured (ΔE = ΔZ). Recalculation is performed so that the endpoint is reset). As described above, in the displacement sensor to which the present invention is applied, the end point E follows the glass substrate surface optical image 72 at a predetermined distance ΔZ (the thickness ΔD> ΔZ of the glass substrate). The glass substrate back surface image 73 does not enter the area 1, and the nonconformity that may occur when the glass substrate back surface image 73 is measured to enter the area 1 does not occur.

In the displacement sensor to which the present invention is applied, a general flow chart showing a procedure for determining a measurement area is shown in FIG. 9 and an explanatory diagram corresponding to the flow in FIG. 9, respectively. In the figure, A, B, Z (x), P (z), ΔZ1, ΔZ2, ΔZ, ΔG, and ΔdAB are as follows.

A: CCD light receiving position behind photo mask, unit (pix)

B: CCD light receiving position on the surface of the glass substrate, unit (pix)

Z (x): Conversion formula from CCD light receiving position (pix) to distance value (mm) (mm)

P (z): Conversion formula from distance value (mm) to CCD light receiving position (pix)

ΔZ1: Offset value up to the start point of the area 1 with respect to the measured value of the area 0.

ΔZ2: Offset value to the end point of area 1 relative to the measured value of area 0.

ΔZ: Fixed value to the end point of area 1 relative to the measured value of area 1

ΔG: Distance between the light receiving position A on the back side of the photomask and the light receiving position B on the surface of the glass substrate when performing exposure processing

ΔdAB: Distance between the light receiving position A on the back side of the photomask and the light receiving position B on the glass substrate surface

Waiting is continued until the setting process start signal of a measurement area is received (step 901, step 902 NO), and when the start signal for effecting measurement area determination processing is received (step 902 YES), the image of the area 0 is received. Is obtained and the area provisional setting processing of the area 1 is performed based on the positional information of the light receiving position A (step 903 YES, step 905). In this example, the position of the photo mask measured in the area 0 is fixed. If no image is detected in the area 0 in step 903 (step 903 NO), it is determined as an error and error processing is performed (step 904). As the error processing, for example, steps 901 to 903 may be repeated until an image is detected in the area 0, and the user is notified that the image is not detected in the area 0. The guide text may be set to display the guide text.

The area provisional setting process in step 905 will be described with reference to FIG. 10. If an image is detected in the area 0 (step 903 YES in FIG. 9), the light receiving position A of the acquired image is detected (step 9051), and the measurement area of the area 1 is determined based on the information of the light receiving position A. FIG. It temporarily decides (step 9052). Here, the start position and the end position of the area 1 as the measurement area are determined by the following formulas, respectively, based on the position information of the light receiving position A and the predetermined offset values? Z1 and? Z2.

Start position: P (Z (A) + △ Z1)

End position: P (Z (A) + △ Z2)

(DELTA) Z1 and (DELTA) Z2 which determine the starting position, the ending position, and the area | region area of the area 1 are determined suitably in consideration of the thickness of a glass substrate, etc.

When the start position and the end position of the area 1 are determined by the above formula (step 9052), the area provisional setting process is performed based on the information to set the start position and the end position of the area 1 ( Step 9053).

9, when the provisional setting process of the area 1 is complete | finished (step 905), it waits until the image is detected in the area 1 (step 906, step 907 NO). If an image is detected in the area 1 (step 907 YES), the processing proceeds to the reset process of the area 1 (step 908).

The area resetting process of step 908 is demonstrated with reference to FIG. When an image is detected in the area 1 (step 907 YES in FIG. 9), the light receiving position B of the acquired image is detected (step 9081), and the measurement area of the area 1 is based on the information of the light receiving position B. Is determined again (step 9082). Here, the start position and the end position of the area 1 as the measurement area include the position information of the light receiving position A, the position information of the light receiving position B, predetermined offset values ΔZ1 and ΔZ2, and fixed values Δ It is calculated | required by the following formula, respectively, by Z).

Start position: P (Z (A) + △ Z1)

End position: P (Z (B) + △ Z)

(DELTA) Z1, (DELTA) Z2, (DELTA) Z which determines the starting position, the ending position, and the area | region of the area | region 1 are determined suitably in consideration of the thickness of a glass substrate, etc.

When the start position and end position of the area 1 are re-determined by the above formula (step 9082), the area provisional setting processing of the area 1 is performed based on the information (step 9083).

Returning to FIG. 9, when the resetting process of the area 1 is complete | finished (step 908), it is determined whether the gap between the light receiving position A and the light receiving position B reached the prescribed value (DELTA G) (step) 909). When the prescribed value DELTA G has not been reached (step 909 NO), the work B is repositioned (step 910), and the gap between the light receiving position A and the light receiving position B is defined. Steps 908 to 910 are repeated until When the gap between the light receiving position A and the light receiving position B reaches the prescribed value DELTA G (step 909 YES), the exposure process is performed on the glass substrate and the processing is terminated (step 911).

A timing chart showing the sensitivity adjustment processing for each region is shown in FIG. As shown in the figure, in the displacement sensor of this embodiment, when one or two or more measurement target regions are set within the field of view of the two-dimensional CCD, the density of the beam irradiation point in each measurement target region is reduced. It is always automatically adjusted to the correct concentration for the measurement.

That is, in Fig. 13, as shown by contrasting the column of the VD signal shown in (a) and the column of the region setting shown in (b), the regions 1 are alternately arranged in a vertical period in which phases are continuous. ) And region 0, and control of light reception sensitivity is performed time-divisionally. As a result, when two image peaks exist in the field of view of the two-dimensional CCD, and one of them is extremely large or small compared to the other, the automatic sensitivity adjustment function by this time division switching is activated, so that any peak The determination process of the measurement point coordinates can be performed at an appropriate concentration.

That is, in the example of FIG. 13, the image included in the region 0 is insufficient in concentration, but as a result of the automatic adjustment of the concentration sequentially, the measurement point coordinates are extracted by using a feature calculation at the time when the concentration is increased to the appropriate concentration. This is done. On the other hand, since the video included in the area 1 has an appropriate density from the beginning, the measurement point coordinates are determined as it is based on this. In the displacement sensor of the present application, the automatic concentration measurement is performed for each region as described above. Therefore, the measurement point coordinates are determined at the appropriate concentration in any image, and the target measurement (for example, the thickness of the transparent body) is performed. Measurement, etc.) becomes possible.

14 is a timing chart showing a process of following the set area with the up and down variation of the measurement point. In this invention, the measured value of a glass substrate surface is always monitored, and when a fluctuation arises in this, it controls so that the end point of a measurement area may follow the distance of (DELTA) Z according to the fluctuation amount. That is, as shown in FIG. 13, in this embodiment, the range of the area | region 1 is recalculated based on the positional information of the glass substrate surface optical image in the area | region 1, and the area range is changed by the result. do. Since the range of the area | region 1 also changes in accordance with the position of a glass substrate, the reflected light on the back surface of a glass substrate always exists outside the area | region 1, and the inadequate measurement by the image on the back surface of a glass substrate can be avoided.

Next, a block diagram schematically showing the internal configuration of the controller of the displacement sensor to which the present invention is applied is shown in FIG. In the figure, 1501 is a sensor head, 1502 is a controller, 1503 is an A / D converter, 1504 is an area determining unit, 1505 is an image memory, 1506 is a display synthesizing unit, 1507 is a D / A converter, 1508 is displacement, concentration extraction. 1509 is a console interface, 1510 is an external I / O interface, 1511 is a memory, 1512 is a CPU, 1513 is an area setting unit, 1514 is an arithmetic unit, and 1515 is a sensitivity determination unit. The calculation unit 1514 incorporates various arithmetic functions such as pixel / mm conversion arithmetic, measurement processing arithmetic, affirmative determination arithmetic, and display arithmetic.

The CPU 1512 is mainly composed of a microprocessor. In this example, three functions of the area setting unit 1513, the calculation unit 1514, and the sensitivity determination unit 1515 are realized in software. The area setting unit 1513 has a function of setting a measurement target area in the field of view of the two-dimensional CCD constituting the sensor head unit 1501 in response to a predetermined operation of the console interface 1509. This measurement object area limits the image of the area | region which is to be measured among all the images picked up by a 2D CCD. The measurement target area set by this area setting unit 1513 is notified to the area determination unit 1504, where it is used as a reference for the area determination processing.

On the other hand, the area determining unit 1504 selectively gates the digital video signal sent from the sensor head 1501 through the A / D converter 1503 corresponding to the area set by the area setting unit 1513. That is, when the set measurement object area | region exists 1 or 2 or more in a list, only the pixel output string of a measurement object area | region is extracted and extracted by passing a digital video signal at the timing of those measurement object area | regions. Create an image. The extracted image thus obtained is sent from the area determining unit 1504 to the image memory 1505 and temporarily stored in the image memory 1505.

The extracted image stored in the image memory 1505 is synthesized by the display image synthesizer 1506 and the graphic image representing the boundary line of the measurement target region and the like sent from the area setting unit 1513, and the synthesized image obtained in this manner is D Raw image data sent to the image monitor via the / A converter 1507 and captured by a two-dimensional CCD on a screen not shown by the image monitor and masked by the area determination unit 1504, or each It is displayed with the line bright waveform etc. which show the density distribution (luminance distribution) of a display line. In addition, this display aspect is demonstrated in detail, referring a screen explanatory drawing later.

As described above, in the displacement sensor in this embodiment, the projection means including the laser diode for forming the optical spot for measurement on the measurement target object and the measurement target object on which the optical spot is formed are photographed from a predetermined angle. It has a light receiving means including a two-dimensional CCD and an arithmetic means for calculating the target displacement based on one information of the light spot image in the image obtained from the light receiving means.

Further, feature extraction means for extracting an image characteristic correlated with the magnitude of a video signal on a light spot from an image obtained from the light receiving means, and comparing the extracted image feature with a predetermined reference value And control means for controlling the magnitude of the video signal on the light spot used for the displacement calculation operation by operating the light transmitting gain adjusting element of the light transmitting means and / or the light receiving gain adjusting element of the light receiving means. .

With the displacement sensor to which the present invention is applied, an example of the screen display when setting the thickness of the glass substrate is shown in Figs. 16 to 18 will be described in detail the setting procedure.

First, Fig. 16A shows a menu screen at the start of setting. In this example, as the application branch, "surface displacement", "spot displacement", "maximum height", "groove, dent", "step", "transparent body thickness", "step difference (2 sensors)", "thickness" (2 sensors) ”is displayed, and in Fig. 16A," transparent body thickness "is selected from these items, and a corresponding display is displayed on the right side of the screen.

When "transparent body thickness" is selected, the screen of FIG. 16 (b) is displayed. In the upper half of the screen, an optical image 1601 on the surface of the transparent body and an optical image 1602 on the rear surface of the transparent body are displayed, and "the measurement area designation of the surface" and a guide sentence are displayed. First, in order to designate the measurement area of the surface optical image of the transparent body, the cursor 1603 is set in accordance with the surface optical image 1601 for designation processing. When the measurement area designation of the surface is performed, the screen of Fig. 17A is displayed in order to continue to designate the measurement area on the back side, and the guide sentence is displayed, "Please make only two surfaces into the measurement area." Similarly to the case of the surface, the cursor 1603 is aligned with the optical image 1602 on the back surface of the transparent body, and designation processing is performed.

When the measurement area designation of the front surface and the back surface of the transparent body is finished, the screen of Fig. 17B is displayed, and the processing procedure for correcting the refractive index is shown. In the figure, the guide sentence "Please input the measurement value of point 1" is displayed. When the measured value of point 1 is input as specified, the screen of FIG. 18 (a) is displayed next, and the guide sentence "Please input the distance between two points" is displayed. Also in this case, enter the distance between two points as in the previous case, and proceed to the next step.

Finally, the screen of Fig. 18B is displayed for confirmation, and an item name and a selection branch of whether or not to register this setting are presented. In this case, "registration" is selected for registration, "return" for correction, and "cancellation" for canceling the setting itself.

An example of the screen configuration of the displacement sensor to which the present invention is applied is shown in FIG. 19. In the figure, 1901 denotes an area (0) in which an optical image on the back side of the photomask is displayed, 1902 denotes an area (1) in which an optical image on the surface of the glass substrate is displayed, 1903 denotes an image on the back surface of the photomask, 1904 an image on the surface of the glass substrate, Is the line bright display on the back of the photomask, 1906 is the line bright display on the surface of the glass substrate, 1907 is the light receiving sensitivity of the area (0) and the peak value of the light image in the area (0), 1908 is the light receiving sensitivity and area of the area (1) The peak value of the optical image in (1) is shown, respectively.

As described above with respect to one embodiment of the present invention, according to the displacement sensor of the present invention, it is possible to completely exclude the influence of the optical image on the back surface of the transparent body by simple operation, and can be applied to various applications. For example, in the embodiment, when the line beam is irradiated, but when the spot beam is irradiated instead of the line beam, the displacement is similarly maintained by using the one-dimensional imaging element with the other parts having the same configuration or by replacing the two-dimensional imaging element. Measurement is possible.

As is apparent from the above configuration, according to the present invention, since the end point of the measurement target region is determined by the measurement point coordinates in the measurement target region, the displacement sensor capable of always measuring the surface of the transparent body regardless of the difference in reflectance between the front surface and the rear surface of the transparent body It is possible to provide.

Claims (14)

One surface of the first transparent plate is fixed and disposed so as to be included in the measurement target area, and the beam is directed toward the measurement target area while approaching the second transparent plate from a position apart from a predetermined distance by facing the surface. Irradiates the image to be measured by the imaging element from an angle different from the irradiation angle of the beam, and reflects the reflective surface reflecting the beam of the first transparent plate and the beam of the second transparent plate. As a method of measuring the displacement based on the optical image of the reflecting surface, Before measuring the displacement, The 1st measurement object area | region is set in the visual field of the said imaging element in the range which the optical image of the reflective surface by one surface of the said 1st transparent plate can be imaged, In a state in which the second measurement target region is located at a position away from the predetermined distance opposite to the one surface by the second transparent plate, the surface far from the first transparent plate of the second transparent plate. It is set in the range which does not include the optical image of the reflecting surface by and does not overlap with the said 1st measurement object area | region, In the measurement of the displacement, Irradiating a beam toward the measurement target area while repeatedly approaching the second transparent plate from a position at least a predetermined distance facing the reflective surface of the first transparent plate, and repeatedly photographing by the imaging device, For each imaging, the position of the end portion on the side opposite to the first measurement target region with respect to the alignment direction of the optical image of the reflecting surfaces in the first and second measurement target regions with respect to the second measurement target region, Based on the optical image of the reflecting surface existing in the measurement target region of 2 to be within a predetermined range, The sensitivity of the first and second measurement target areas is automatically adjusted based on the light reception amount on the reflective surface having the largest amount of light received in each measurement target area or on the reflection surface selected by a predetermined condition, and each obtained by sensitivity adjustment. The measurement point coordinates are respectively determined from the optical image of the reflecting surface of the object existing in the measurement target region of H, and the displacement of the reflection surface in the first measurement target region and half of the second measurement target region based on the determined measurement point coordinates. Displacement measuring method characterized by measuring the displacement of the slope. The distance between a 1st transparent plate and a 2nd transparent plate from the displacement of the reflection surface in the 1st measurement object area | region obtained by the method of Claim 1, and the displacement of the reflection surface of the said 2nd measurement object area | region. The gap measurement method characterized by calculating the. The method of claim 1, Regarding the alignment direction of the optical images of the reflective surfaces in the first and second measurement target regions within a predetermined range based on the optical image of the reflective surfaces existing in the region, which follows the end of the second measurement target region, A displacement measuring method characterized by being larger than the width of the optical image of the reflective surface and smaller than an interval in the field of view of the imaging device corresponding to the thickness of the second transparent plate. The method of claim 1, A displacement measuring method, characterized in that the second transparent plate is approached from outside the field of view of the imaging device. The method of claim 1, And the beam is a line beam. The method of claim 2, The second transparent plate is a glass substrate used for an FPD (flat panel display), and the first transparent plate is a mask glass used for an exposure process. Light transmitting means for irradiating a beam toward a predetermined measurement target area; An imaging device for imaging the measurement target area from an angle different from the irradiation angle of the beam; Measuring means for measuring the displacement of the object in the measurement target region based on the output of the imaging element; Measurement subject region setting means capable of setting two or more measurement subject regions within the field of view of the imaging device; Measurement point coordinate determination means for determining one or two or more measurement point coordinates included in a set measurement target area based on an image picked up by an imaging element; Following the variation of the measurement displacement with respect to the reflecting surface of the measurement object, one end of the measurement object region of the measurement object region including the reflection surface of the measurement object with which the measurement displacement is varied in the direction of the variation of the measurement displacement. It is provided with the area | region automatic tracking means to move, The measurement target region has at least a first measurement target region and a second measurement target region, and sets the first measurement target region with respect to the reflective surface which is fixed and exists in the field of view of the imaging device, and the measurement displacement varies. As for the reflective surface of the object, a second measurement target region is set in a range other than the first measurement target region so as to include the reflection surface. The area automatic tracking means moves the end of the second measurement target area on the side opposite to the first measurement target area with respect to the alignment direction of the optical image of the reflecting surfaces in the first and second measurement target areas. Displacement sensor. The method of claim 7, wherein The second measurement target region sets one end portion in the direction of the measurement displacement in the field of view of the imaging device as a terminal. The method of claim 8, The coordinate of the edge part of the side of a 1st measurement object area | region in the direction of the measurement displacement in the visual field of the imaging element of a 2nd measurement object area | region is set based on the measurement point coordinate of the image contained in the 1st measurement object area | region, The coordinates of the edge part on the opposite side to the 1st measurement object area | region in the direction of the measurement displacement in the visual field of the imaging element of a 2nd measurement object area | region, When the image is not included in the second measurement target region, one end in the direction of the measurement displacement in the field of view of the imaging device is set as the terminal, When an image is contained in a 2nd measurement object area | region, a displacement sensor is set based on the measurement point coordinate of the image contained in a 2nd measurement object area | region. The method of claim 9, In the case where the displacement of the image included in the second measurement target region is measured, the coordinates of the second measurement target region end point are reset based on the measurement point coordinates of the image included in the second measurement target region. Displacement sensor. The method of claim 7, wherein A target displacement measurement object is a gap between a glass substrate used for an FPD (flat panel display) and a mask glass used for an exposure process on a glass substrate. The method of claim 9, When an image is contained in a said 2nd measurement object area | region, it is set based on the measurement point coordinate of the image contained in a 2nd measurement object area | region, The distance from the measurement point coordinate of a 2nd measurement object area | region to a terminal is glass Displacement sensor, characterized in that less than the thickness of the substrate. The method of claim 10, The distance from the measurement point coordinates of the 2nd measurement object area | region to the terminal which resets the coordinate of a 2nd measurement object area | region end point based on the measurement point coordinate of the image contained in the said 2nd measurement object area | region is smaller than the thickness of a glass substrate. Displacement sensor, characterized in that. The method of claim 7, wherein Displacement sensor, characterized in that the beam is a line beam.

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