JP2004264082A - Thickness measuring instrument - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To surely notify the propriety of a measuring position, in constitution for measuring a dimension between prescribed planes of a measured object having light transparency, by a distance measurement. <P>SOLUTION: A distance up to the interplanar center position of the measuring object is measured to control a display mode for a display lamp in response to the distance. That is, the display lamp is turned on when the measured distance is positioned in the optimum position in the vicinity of the center position of a measurable range, the display lamp is flickered when positioned in other measurable range, and the display lamp is turned off when positioned outside the measurable ranges. The center between the prescribed planes of the measured object is thereby aligned in the optimum position in the vicinity of the center position of the measurable range. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a thickness measuring device for measuring a thickness dimension of an object to be measured.
[0002]
[Prior art]
[0003]
[Patent Document 1] JP-A-6-74760
[Problems to be solved by the invention]
For example, a displacement sensor measures a distance to an object to be measured, and changes the measured distance to specify an uneven portion or to confirm a surface state. When using such a displacement sensor, it is desirable to position the displacement sensor so that the object to be measured is arranged at the center of the measurable range of the displacement sensor.
[0005]
In Japanese Patent Application Laid-Open No. H6-74760, in order to meet such a demand, the display mode of the indicator light is changed according to the measurement result of the distance to the object to be measured, so that the operator can easily use the displacement sensor. A configuration in which the distance relationship with the object to be measured is grasped and the object to be measured can be positioned at an optimum position near the center of the measurable range is presented.
[0006]
By the way, in recent years, a displacement sensor capable of detecting the thickness of a glass substrate has been provided. This is because, as reflected light on the glass substrate, there are two kinds of reflected light, a surface reflected light reflected on the surface of the glass substrate and a back surface reflected light transmitted through the glass and reflected on the back surface. When the light is received on the CCD, the light receiving distribution on the CCD has two light receiving peaks, front surface reflected light and back surface reflected light. Therefore, the thickness of the glass substrate is measured from the bit position on the CCD corresponding to each light receiving peak. It is to do.
[0007]
However, when the thickness is measured in this way, even if the measured value is the thickness, the display lamp changes the display mode based on the measurement distance, so that the display corresponding to the thickness of the measured object cannot be performed, and the display is not performed. Not only the merit of providing the lamp is not exhibited, but if the measurement is performed according to the display of the indicator lamp, the measurement accuracy may be reduced.
[0008]
The present invention has been made in view of the above circumstances, and an object of the present invention is to surely notify the appropriateness of a measurement position in a configuration for measuring a dimension between predetermined surfaces of an object having light transmittance by distance measurement. It is an object of the present invention to provide a thickness measuring device capable of performing the above-mentioned steps.
[0009]
[Means for Solving the Problems]
The present invention is directed to a light projecting means for irradiating a light-transmitting object with light, a CCD for receiving reflected light from the object, and a light-receiving means for detecting the light-receiving distribution from a plurality of peak positions on the CCD. A measuring device for measuring a dimension between predetermined surfaces of a measurement object, wherein a distance from predetermined two peak positions of a plurality of peak positions of a light reception distribution on the CCD to a center position thereof is determined. Is provided, and a determination unit is provided for determining whether the measurement is suitable for measurement by comparing the measurement distance measured by the distance measurement unit with a preset distance range, and reports a determination result by the determination unit. A notification means is provided (claim 1).
[0010]
According to such a configuration, when light is irradiated from the irradiating means to the object having light transmittance, the light is reflected on the front surface and the back surface of the object to be measured. Two peak values of the light reception distribution are formed. Here, since the distance measuring means measures the distance from those peak positions to their center position, the determining means is suitable for measurement by comparing the distance measured by the distance measuring means with a preset distance range. To determine Since the notifying unit notifies the result of the judgment by the judging unit, the measurement accuracy can be improved by performing the positioning based on the notification by the notifying unit.
[0011]
In the above configuration, the determination unit determines whether the distance measurement by the distance measurement unit is located at an optimum position of the measurable range, a measurable range other than the optimum position, or outside the measurable range. (Claim 2).
According to such a configuration, the center between the predetermined surfaces of the measurement target can be easily adjusted to the optimum position by the notification of the notification unit.
[0012]
A switching unit for switching a measurement mode; and a second distance measurement unit for measuring a distance to a predetermined peak position of a light reception distribution on the CCD when the switching unit is switched to a distance measurement mode. In addition, the determining unit may determine whether the measurement is suitable for the measurement by comparing the distance measured by the second distance measuring unit with a predetermined distance range (claim 3). ).
[0013]
According to such a configuration, when measuring the distance to the measured object, the switching unit is switched to the distance measurement mode. Then, the second distance measuring means measures the distance to a predetermined peak position of the light receiving distribution on the CCD, and the determining means compares the measured distance of the second distance measuring means with a preset distance range. Thus, it is determined whether or not the measurement is suitable. Therefore, by performing positioning based on the notification by the notification unit, the measurement accuracy can be improved.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described below with reference to the drawings.
FIG. 2 is a perspective view of the thickness measuring device. In FIG. 2, the thickness measuring device 1 includes a sensor head 2 and a controller 4 having a display 3.
[0015]
FIG. 1 is a block diagram illustrating an electrical configuration of the thickness measuring device 1. In FIG. 1, the sensor head 2 includes a light emitting element 5 composed of, for example, a red semiconductor laser diode as a light emitting means, a light emitting element driving circuit 6 for supplying a driving current to the light emitting element 5, a CCD 7 for receiving reflected light, It is provided with a CCD drive circuit 8 for driving the CCD 7 and an indicator light (corresponding to a notifying means) 9 for notifying the appropriateness of the measurement position.
[0016]
The controller 4 includes, in addition to the display 3, an A / D converter 10 for A / D converting an output signal of the CCD 7, a comparator 11 for comparing the output signal of the CCD 7 with a predetermined slice level, a CPU 12, a memory 13, and the like. It is configured.
[0017]
The display 3 is configured to include a touch panel (not shown) as a switching unit, and corresponds to a CPU (corresponding to a measuring unit, a distance measuring unit, a determining unit, a notifying unit, and a second distance measuring unit) in response to a touch operation by an operator. 12) various setting signals are transmitted.
[0018]
FIG. 3 is a schematic diagram illustrating the configuration of the CCD 7. In FIG. 3, the CCD 7 includes a photodiode array unit 7a, a CCD unit 7b, and a charge-voltage converter 7c. The photodiode array unit 7a has a plurality of pixels (light receiving units) arranged in a line. The CCD unit 7b has a plurality of charge holding units corresponding to a plurality of pixels of the photodiode array unit 7a.
[0019]
FIG. 4 is a timing chart showing the operation of the CCD 7. In FIG. 4, charges accumulated in each pixel of the photodiode array unit 7a are simultaneously transferred to the CCD unit 7b in response to a trigger signal TR. The charges transferred to the CCD unit 7b are sequentially shifted by one pixel in the CCD unit 7b in response to the shift pulse SH and output from one end. The charge output from the CCD unit 7b is converted into a voltage by the charge-voltage converter 7c. Thus, an output signal CD corresponding to the amount of received light of each pixel is obtained from the charge-voltage converter 7c.
[0020]
In the controller 4, the output signal CD from the CCD 7 is compared with a predetermined slice level in the comparator 11, and the result is taken into the CPU 12. This is for distinguishing the noise included in the output signal CD from the peak level of the light reception distribution on the CCD 7, and in the CPU 12, when the output from the comparator 11 is at a high level (that is, when the light reception level of the CCD 7 is higher than a predetermined level). Only the output of the A / D converter 10 is taken in as reflected light from the device under test, and a discrimination processing operation described later is performed.
[0021]
Next, the operation of the above configuration will be described.
<Measurement mode setting>
The operator needs to set the measurement mode in advance. That is, any one of the distance to the front surface, the distance to the back surface, the thickness of the measured object, and the gap between the two measured objects is selected as the measurement target.
[0022]
In the present embodiment, four surfaces (the surface of the first glass substrate A) are provided for the two transparent first glass substrates A and the second glass substrates B which are stacked with a gap as shown in FIG. (1), its back surface (2), the front surface (3) of the second glass substrate B, and its back surface (4)), and detects the respective peaks of the reflected light. Based on this, it is possible to measure the distance to the predetermined surfaces of the glass substrates A and B or the dimension between the predetermined surfaces.
[0023]
For example, when measuring the distance to the front surface of the first glass substrate A, the surface (1), when measuring the distance to the back surface, the surface (2), and measuring the distance to the front surface of the second glass substrate B are desired. In this case, the surface (3) is selected, and when it is desired to measure the distance to the back surface, the surface (4) is selected. Separately, the thickness (1)-(2) when measuring the thickness of the first glass substrate A, and the thickness (3)-(4) when measuring the thickness of the second glass substrate B, the first glass When it is desired to measure the gap between the substrate A and the second glass substrate B, each of the thicknesses (2)-(3) is selected.
[0024]
The above selection operation of the measurement mode can be set and operated on the display 3 on the controller 4. The display 3 is a touch panel, and the above-described setting items of the measurement mode are displayed on the screen. Therefore, the operator simply selects a desired measurement item on the screen and performs a touch operation. A setting signal is transmitted to the device, whereby the setting operation of the measurement mode can be performed.
[0025]
<Light receiving sampling>
When the sensor head 2 of the thickness measuring device 1 is driven with a predetermined distance opposed to the glass substrates A and B as objects to be measured, a beam-like laser beam is emitted from the light projecting element 5 to the glass substrates A and B. Is irradiated obliquely. In this case, the CPU 12 is in a state of always outputting a drive signal to the light emitting element drive circuit 6, and the light emitting element 5 is so-called DC light that constantly lights. Therefore, since the laser light is always emitted from the light projecting element 5 to the glass substrates A and B and reflected, the reflected light is received on the CCD 7.
[0026]
In the example shown in FIG. 5, the surface reflected light reflected on the surfaces of the first glass substrate A and the second glass substrate B and the back surface reflected light reflected on the back surfaces thereof are irradiated on the CCD 7, so that the CCD 7 A light receiving distribution is formed by the reflected light. This light receiving distribution has a peak corresponding to the light receiving position of the reflected light from the glass substrates A and B. That is, the light receiving center position of the front surface reflected light and the back surface reflected light from the glass substrates A and B is the peak position.
The CPU 12 outputs a trigger signal TR to the CCD drive circuit 8 when receiving the light receiving signal. The CCD drive circuit 8 is constituted by a shift register, and when receiving the trigger signal TR, sequentially supplies a shift pulse SH to the CCD 7.
Upon receiving the trigger signal TR and the shift pulse SH, the CCD 7 sequentially outputs an output signal CD of a level corresponding to the amount of received light for each bit (see FIG. 6).
[0027]
The CPU 12 refers to the output level of the comparator 11 at each timing of the shift pulse SH, and indicates the number of bits when changing from the low level to the high level (corresponding to the number of times the output of the comparator 11 is referred to). First, the peak measurement start bit S1a is stored.
[0028]
When the output of the comparator 11 changes to a high level, the output signal of the A / D converter 10 is fetched until the next change to a low level, and the bit number S1P corresponding to the peak value is stored. That is, each time the output signal of the A / D converter 10 is captured, the peak level can be determined by updating and storing the higher one as the peak level as compared with the stored peak level. At this time, by simultaneously storing the number of bits corresponding to the peak level, the number of bits corresponding to the peak level can be determined and stored.
[0029]
Next, when the output of the comparator 11 changes from the high level to the low level, the peak measurement end bit number S1b, which is the bit number at that time, is stored.
The CPU 12 repeats the above operation until the last bit, and when there are four peaks as shown in FIG. 6, the peak measurement start bit numbers S1a, S2a, S3a, S4a and the peak measurement end bits correspond to the peaks. The numbers S1b, S2b, S3b, S4b and the peak position bit numbers S1P, S2P, S3P, S4P are stored.
[0030]
<Distance (thickness) measurement>
The CPU 12 first calculates S1c = (S1a + S1b) / 2 to measure the first peak position in the light reception distribution. In this method, a position of the center of gravity is calculated by a calculation method called a centroid method, and the calculated position is calculated as the number of bits at the peak position.
[0031]
In the present embodiment, S1 obtained by the calculation of S1 = (S1c + S1P) / 2 is used as the bit number of the final peak position (see FIG. 6). This is because the peak position of the received light waveform is simply S1P, but S1P may be shifted due to the influence of noise. Therefore, the accuracy is improved by obtaining the average of S1c and S1P obtained by the centroid method. Is to try.
Similarly, the number of peak position bits S2, S3, and S4 corresponding to the second, third, and fourth peak positions in the light reception distribution are calculated.
[0032]
In the distance measurement, the CPU 12 obtains the distance from these bit numbers S1, S2, S3, and S4. Specifically, by storing data in which the number of bits and the distance are associated in advance in the memory 13, the corresponding distance can be read from the number of bits at the time of distance measurement. That is, at the time of setting, when the plane (1) is set as the measurement plane, the distance L1 corresponding to the bit number of S1 is set, and when the plane (2) is set, the distance L2 corresponding to the bit number of S2 is set. However, when plane (3) is set, distance L3 corresponding to the number of bits of S3 is obtained as a measured value, and when plane (4) is set, distance L4 corresponding to the number of bits of S4 is obtained as a measured value. be able to.
[0033]
On the other hand, in the case of thickness measurement, for example, taking the surface (1)-(2) as an example, the distance L1 to the surface (1) and the distance L2 to the surface (2) are determined in the same manner as in the above distance measurement. As a result of calculating the difference L12 = L2-L1, L12 is obtained as the thickness of the surface (1)-(2) of the first glass substrate A. Similarly, L23 = L3-L2 is a gap between the surfaces (2)-(3) of the first glass substrate A and the second glass substrate B, and L34 = L4-L3 is a surface (3)-of the second glass substrate B. It is obtained as the thickness of (4).
[0034]
A display signal is output from the CPU 12 to the display 3 and displayed on the display 3 for each of the above measurement results. Therefore, the operator can check any one of the distance to the front surface, the distance to the back surface, the thickness of the measured object, and the gap between the two measured objects set in the setting mode.
[0035]
<Indicator light control>
When the measurement mode is the distance measurement, the CPU 12 controls the indicator lamp 9 based on the distance measurement result. FIG. 7 shows the correspondence between the distance measurement result and the indicator light control. In FIG. 7, for example, when the measurement surface is the distance measurement of the surface (1) of the first glass substrate A, the distance measurement result L1 of the surface (1), the measurable range M1 to M2, and the center position of the measurable range The display mode of the indicator light 9 is controlled by comparing with the optimum positions M2 to M3 and the measurable ranges M3 to M4. That is, in the case of M2 <L1 <M3, a DC signal is given to the indicator lamp 9 in order to turn on the indicator lamp 9 to notify that it is the optimum position of the measurable range. When M1 <L1 ≦ M2 or M3 ≦ L1 <M4, a pulse signal of a predetermined cycle is given to the display lamp 9 so as to blink the display lamp 9 to notify that it is within the measurable range. In the case of L1 ≦ M1 or M4 ≦ L1, the signal stop state to the indicator lamp 9 is maintained so as to turn off the indicator lamp 9 to notify that it is out of the measurable range.
[0036]
Similarly, L2 is measured when measuring the back surface (2) of the first glass substrate A, L3 is measured when measuring the front surface (3) of the second glass substrate B, and L4 and M1, M2, when measuring the back surface (4). The display mode of the indicator lamp 9 is controlled by comparison with M3 and M4.
Therefore, the operator performs the positioning of the sensor head 2 so that the display mode of the indicator lamp 9 is turned on.
[0037]
On the other hand, when the measurement mode is the thickness measurement, the measurement is performed as follows.
When measuring the thickness of the first glass substrate A, the CPU 12 calculates the distance L12 between the center positions of the thicknesses {1}-{2} of the first glass substrate A by an arithmetic expression L12 = L1 + (L2-L1) / 2. The L12 is obtained and compared with M1, M2, M3, and M4 in the same manner as in the above distance measurement to control the display mode of the indicator lamp 9.
[0038]
Similarly, when measuring the gap (2)-(3) between the first glass substrate A and the second glass substrate B, the arithmetic expression L23 = L2 + (L3-L2) / 2, and the thickness {3} of the second glass substrate B At the time of measurement of (4)-(4), control of the display mode of the indicator lamp 9 is performed by comparing the value obtained by the calculation formula with M1, M2, M3, M4 using the calculation formula L34 = L3 + (L4-L3) / 2. I do.
Therefore, the operator performs the positioning of the sensor head 2 so that the display mode of the display lamp 9 is turned on.
[0039]
According to such an embodiment, at the time of measuring the thickness, the indicator lamp 9 is set according to the distance to the center of the thickness of the glass substrates A and B or the distance to the center of the gap between the glass substrates A and B. Is performed, the display control corresponding to the center position between the predetermined surfaces of the glass substrates A and B can be performed. Therefore, the control of the display mode of the indicator light 9 can be effectively exerted even at the time of thickness measurement, and high measurement accuracy is ensured by positioning the display device 9 based on the display mode of the indicator light 9. be able to.
[0040]
(Modification)
The present invention is not limited to the above embodiment, but can be modified or expanded as follows.
As a method of obtaining the center distance at the time of measuring the thickness, for example, when the number of peak bits S1 and S2 is obtained at the time of measuring the thickness of the surface (1)-(2) of the first glass substrate A, the operation S12 = The center bit number may be obtained by (S1 + S) / 2, and the distance corresponding to the center bit S12 may be read from the memory to obtain the center distance L12.
[0041]
The size between the front surfaces of two glass substrates or the size between the back surfaces of the glass substrates may be measured.
The dimension between predetermined surfaces of three or more glass substrates may be measured.
As the control of the display mode of the indicator lamp 9, it may be turned on in a measurable range and turned off outside the measurable range, or may be turned on at an optimum position and turned off at other positions.
[0042]
【The invention's effect】
As is apparent from the above description, according to the thickness measuring apparatus of the present invention, the distance from the predetermined two peak positions of the plurality of peak positions of the light reception distribution on the CCD to the center position thereof is measured. Since the distance is compared with a preset distance range to notify whether or not the measurement is appropriate, it is possible to provide an excellent effect that the appropriateness of the measurement position can be reliably notified.
[Brief description of the drawings]
FIG. 1 is a block diagram schematically showing an overall electrical configuration according to an embodiment of the present invention. FIG. 2 is an overall perspective view. FIG. 3 is a schematic diagram showing a configuration of a CCD. FIG. 5 is a side view showing a measurement state of two glass substrates. FIG. 6 is a view showing a light reception distribution on a CCD. FIG. 7 is a view showing a relationship between a measurement distance and an indicator light control. Explanation of code]
1 is a thickness measuring device, 2 is a sensor head, 3 is a display (switching means), 5 is a light emitting element (light emitting means), 7 is a CCD, 9 is an indicator light (notifying means), and 12 is a CPU (measuring means). , Distance measuring means, determining means, notifying means, and second distance measuring means).

Claims (3)

Light projecting means for irradiating the object to be measured with light transmittance with light,
A CCD for receiving reflected light from the object to be measured;
Measuring means for measuring a dimension between predetermined surfaces of the object from a plurality of peak positions of the light reception distribution on the CCD,
Distance measuring means for measuring a distance from predetermined two peak positions of a plurality of peak positions of the light reception distribution on the CCD to a center position thereof;
Determining means for determining whether or not the distance measured by the distance measuring means is suitable for measurement by comparing the distance with a predetermined distance range;
A notifying means for notifying a result of the judgment by the judging means. The determination means determines whether the distance measurement by the distance measurement means is located at an optimum position of a measurable range, a measurable range other than the optimum position, or a position outside the measurable range. Item 3. The thickness measuring device according to Item 1. Switching means for switching the measurement mode;
When the switching unit is switched to the distance measurement mode, the switching unit includes a second distance measurement unit that measures a distance to a predetermined peak position of a light reception distribution on the CCD.
The thickness measuring device according to claim 1, wherein the determining unit determines whether the measurement is suitable for the measurement by comparing a distance measured by the second distance measuring unit with a predetermined distance range. apparatus.

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