JP2004119835A - Device for detecting thin substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a small-size device for stably detecting thin substrates. <P>SOLUTION: The device for detecting thin substrates is arranged such that the thin substrates 1 accommodated in a cassette 2 are detected by means of a photoelectric sensor which is disposed adjacent to the cassette 2 and can be moved in one direction by a driving means 5, and that the conditions of the thin substrates 1 are judged by a judging means 6 based on the signals outputted from the photoelectric sensor. The photoelectric sensor is provided with an optical condenser 4 for condensing light that has been scattered around the thin substrates 1, and a light receiving element 3 for receiving the light that has been condensed by the condenser 4 for conversion into electric signals. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a thin substrate detecting device for detecting a thin substrate such as a glass substrate housed in a cassette.
[0002]
[Prior art]
FIG. 7 is an explanatory diagram of a conventional thin substrate detection device. As shown in FIG. 7, a reflection type sensor 20 is conventionally used to detect a thin substrate accommodated in a cassette. The reflection type sensor 20 irradiates a thin beam light 21 such as a laser beam or an LED light to an end surface of the thin substrate 1 and detects the reflected light to determine the presence or absence of the thin substrate 1. In order to detect all the thin substrates 1 in a cassette (not shown), the reflection sensor 20 is moved in the direction of arrow 22 using a driving device (not shown).
In addition, there is one using a transmission type sensor in which a light projecting element and a light receiving element are arranged with a cassette interposed therebetween (for example, see Patent Document 1).
Further, there is an image sensor type that detects an end face of the thin substrate 1 using a CCD camera, performs image processing such as binarization processing and edge processing on the taken image, and detects the thin substrate.
[0003]
[Patent Document 1]
JP-A-9-148403 (page 2-8, FIG. 3)
[0004]
[Problems to be solved by the invention]
However, in the conventional reflection-type thin substrate detection method, the reflected light does not return depending on the shape of the end surface of the thin substrate 1 because it depends on the presence or absence of the reflected light of the light beam 21 or the intensity of the reflected light. The reflected light is weakened by the reflectivity of the film formed on the surface of the thin substrate 1, so that there is a problem that it is erroneously determined that the thin substrate 1 actually does not exist.
[0005]
Further, in the transmission type sensor, since the light projecting element and the light receiving element are arranged with the cassette interposed therebetween, there is a problem that the apparatus is enlarged.
In addition, when the image sensor is used, if the subject and the image sensor are continuously moved relative to each other, the image is blurred.
[0006]
Therefore, an object of the present invention is to provide a small thin substrate detecting device capable of stably detecting a thin substrate.
[0007]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, a thin substrate detection device of the present invention detects a thin substrate housed in a cassette by using a photoelectric sensor that is disposed adjacent to the cassette and can be moved in one direction by a driving unit. A thin substrate detecting device that determines a state of the thin substrate from an output signal of the photoelectric sensor by a determination unit, wherein the photoelectric sensor includes an optical condensing unit that condenses scattered light around the thin substrate; A light-receiving element for receiving the light condensed by the light condensing means and converting the light into an electric signal.
[0008]
The photoelectric sensor capable of detecting scattered light (natural light) is driven by a driving unit and receives peripheral scattered light due to indoor lighting or the like. This scattered light is light emitted from indoor lighting or the like, and thus usually has a small amount of light. However, since the optical condensing means is provided, the scattered light enters the light receiving surface of the light receiving element after being condensed. On the other hand, when the photoelectric sensor approaches the thin substrate, the thin substrate blocks the scattered light, so that the amount of light received by the photoelectric sensor decreases. The light receiving element converts the received light into an electric signal, and transmits the electric signal to the judging means. The judging means judges a state such as the presence or absence of the thin substrate based on whether the electric signal exceeds a threshold value.
[0009]
When a plurality of the photoelectric sensors are arranged in a line along the moving direction, a differential value can be calculated from a difference or a sum between outputs of the respective light receiving elements.
[0010]
If the photoelectric sensor is provided with a divided light receiving element in which one light receiving surface is divided into a plurality of parts, the distance between adjacent sensor portions is reduced, so that the measurement accuracy is improved and the device can be downsized.
[0011]
The determination means is provided with a circuit for determining a state of the thin substrate by binarization processing, primary differentiation processing or secondary differentiation processing from output values of the plurality of photoelectric sensors or the photoelectric sensors having the divided light receiving elements. Thus, a device having a simple configuration can be formed without using a CPU.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(First Embodiment)
FIG. 1 is a configuration diagram of a thin substrate detection device according to a first embodiment of the present invention. As shown in FIG. 1, the thin substrate detecting apparatus according to the first embodiment of the present invention is arranged such that a thin substrate 1 accommodated in a cassette 2 is disposed adjacent to the cassette 2, This is a device that detects using a photoelectric sensor that can move in the direction (1) and determines the state of the thin substrate 1 from the output signal of the photoelectric sensor by the determination unit 6.
[0013]
The cassette 2 has front and rear openings, and a guide groove for horizontally arranging the thin substrate 1 is formed inside the side wall. The thin substrate 1 is formed in a flat plate shape, and is accommodated in a cassette 2 in multiple stages. The driving means 5 which supports the photoelectric sensor from below and can move up and down moves at a constant speed, but is provided so as to be movable by a small distance according to an input pulse, or a linear scale (not shown) capable of measuring the current position. ) May be provided to obtain the current position.
[0014]
The photoelectric sensor includes an optical condensing unit 4 including a lens and a prism, and a light receiving element 3 including a photodiode and a phototransistor and performing photoelectric conversion at high speed. , Are arranged at positions facing the end face of the thin substrate 1.
[0015]
The optical condensing means 4 is arranged on the light receiving surface of the light receiving element 3 and can condense surrounding scattered light. Further, the light receiving element 3 can receive the light condensed by the optical condensing means 4 and convert it into an electric signal.
[0016]
By mounting the photoelectric sensor on the driving means 5 and moving it up and down as shown by the arrow 10, the brightness information near the end faces of all the thin substrates 1 in the cassette 2 can be detected.
[0017]
Here, the principle of thin substrate detection will be described. FIG. 2 is a front view of a cassette storing a plurality of thin substrates. As shown in FIG. 2, the end face of the thin substrate 1 stored in the cassette 2 is shown in black, because the surrounding environment is bright and the end face looks darker than the surroundings. A portion indicated by a dotted line of the third slot 1 ′ from the top in the cassette 2 indicates that the thin substrate 1 is not stored.
[0018]
FIG. 3 is a graph showing the relationship between the position of the light receiving element and the received light intensity. The vertical axis indicates light intensity, and the brighter the value, the larger the value. The horizontal axis indicates the position of the light receiving element on the broken line A in the height direction.
[0019]
When a light-receiving element such as a photodiode capable of converting light to electricity is moved vertically along a broken line A in FIG. 2, an output signal as shown in FIG. 3 is obtained. The dotted line B shows the case where the thin substrate 1 is present in the slot 1 'of FIG. 2, but in practice, since the slot 1' does not have the thin substrate 1, the light intensity remains strong as shown by the solid line. It has become.
The thin substrate 1 is detected by processing this signal by the determination means 6.
[0020]
The determination means 6 has an AD converter 11 for converting an output signal from the light receiving element 3 into a digital signal, and a CPU 12 for processing the converted digital signal.
[0021]
Several processes for detecting the presence or absence of the thin substrate 1 performed by the CPU unit 12 are conceivable. Generally, a threshold value as shown by a broken line C in FIG. 3 is provided, and the presence or absence of the thin substrate 1 can be detected by comparing the threshold value (this process is referred to as a binarization process).
[0022]
First, values obtained by sampling the output from the AD conversion unit 11 at regular time intervals T are denoted by D ₁ , D ₂ ,..., D _i , D _{i + 1} ,. Here, the subscript i is an integer, and Di is a sampling value at time T × i. In this case, the drive unit 5 performs sampling on the basis of time on the assumption that the drive unit 5 is moving at a constant speed. It is desirable to do.
[0023]
For example, when the surroundings become dark due to the presence of the thin substrate 1, the value of the output signal becomes lower than the threshold value. Further, when there is no thin substrate 1, the value of the output signal remains higher than the threshold value. That is, in the binarization process, it is determined that there is no substrate when D _i > C, and it is determined that there is a substrate when D _i <C from the magnitude relationship of the preset threshold value C.
[0024]
It is also conceivable that two or more thin substrates 1 are stored in one slot in an overlapping manner. In this case, a threshold value is set for the time during which the presence of the substrate is continuous, and when the measured value is larger than the threshold value, it is determined that a plurality of thin substrates 1 are overlapped.
[0025]
It is also conceivable that one thin substrate 1 is inserted astride two slots and arranged obliquely. In this case, the direction of reflection of the ambient light by the end surface of the thin substrate 1 shifts upward or downward, and the light reflected by the upper or lower surface of the thin substrate 1 is recognized by the optical condensing means. The thin substrate 1 is recognized at a position different from the above. In the binarization process, the position range of the slot is set in advance, and when the value of the output signal becomes smaller than the threshold value at a position outside this position, it is determined that oblique insertion is performed.
[0026]
The situation such as the presence or absence of the thin substrate 1, the overlapping of two substrates, and the oblique insertion results in the same appearance regardless of the end face shape of the thin substrate 1 and the state of the film on the substrate surface, and the same light intensity is obtained. Therefore, even in the case where it is difficult to use the conventional reflection-type sensor as described above, it is possible to stably detect the thin substrate 1 with this method.
[0027]
In addition to the binarization processing, a method of calculating the first derivative to obtain the falling D and the rising E corresponding to the boundary of the end face of the substrate, or calculating the second differential to obtain the center F of the end face may be considered. .
[0028]
In first derivative, for example, calculates the _{D i} + 1 -D _i. A point at which the calculated value becomes negative is defined as falling D, and a point at which the calculated value is positive is defined as rising E, and it is determined that there is a substrate between D and E, and that there is no substrate between E and D.
[0029]
In the second derivative, for example, calculates the _{D i-1 + D i +} 1 -2 · D i. The maximum of the calculated value is at the center F of the end face in FIG. 3, and the center F is compared with the sampling position to determine the presence or absence of the board or the oblique insertion. The detection accuracy can be improved by performing a combination of two or more of the binarization processing, the primary differentiation processing, and the secondary differentiation processing.
[0030]
(Second embodiment)
FIG. 4 is a configuration diagram of a thin substrate detection device according to a second embodiment of the present invention. The thin substrate detecting apparatus according to the second embodiment has a configuration in which two photoelectric sensors used in the thin substrate detecting apparatus according to the first embodiment described above are arranged in the vertical direction. 14 is used. That is, two sets of light receiving elements (3 and 3 ') and optical means (4 and 4') are vertically arranged. Then, in the determination means 6 'for processing each signal, the difference between the two signals is calculated by the arithmetic unit 13 constituted by hardware. That is, when the outputs of the light receiving elements 3 and 3 ′ are P ₁ and P ₂ , P ₂ −P ₁ is calculated, and this value is compared with a threshold value Q given in advance by the comparing unit 14 to obtain P ₂ When −P ₁ <−Q, the falling D is determined, and when P ₂ −P ₁ > Q, the rising E is determined. This processing has the same contents as the first-order differentiation processing of the first embodiment.
[0031]
As described above, in the present embodiment, two light receiving elements are used. However, by arranging three or more light receiving elements, it is possible to configure the operation of the second derivative with a simple circuit (hardware). .
[0032]
As a method of realizing the determination means 6 ', the same processing may be A / D-converted to two signals and may be operated by the CPU as described in the first embodiment. However, by using hardware as in the present embodiment, higher speed, smaller size, and lower price can be realized as compared with using a CPU.
[0033]
(Third embodiment)
FIG. 5 is a configuration diagram illustrating a connection state between the determination unit of the thin substrate detection device according to the third embodiment and the photoelectric sensor. The thin substrate detection device according to the third embodiment uses a multi-segmented light receiving element having a divided light receiving element obtained by dividing one light receiving surface into a plurality as a photoelectric sensor. The multi-segment light receiving element is one in which a plurality of light receiving sections are integrated on one chip. Note that the configuration of the other parts is the same as that of the thin substrate detection device of the first embodiment, and a description thereof will be omitted.
[0034]
FIG. 6 is a configuration diagram of a two-part optical element. As an example of such a two-part light receiving element, for example, there is a two-part photodiode (S2721-02) manufactured by Hamamatsu Photonics. As shown in FIG. 6, in the two-divided light receiving element, two light receiving sections 8 are arranged on the element 7. In this element, the size of the light receiving section 8 is about 3 mm × 0.5 mm. The generated current changes depending on the amount of light incident on the light receiving unit 8. By detecting this current, the amount of received light can be estimated.
[0035]
As shown in FIG. 5, an output signal from each light receiving section 8 of the three-division light receiving element 9 is processed by the judging means 6 ″. In the judging means 6 ″ of the present embodiment, an arithmetic unit 15 configured by hardware Performs addition and subtraction between signals. Specifically, assuming that the outputs of the light receiving units are P ₁ , P ₂ , and P ₃ from the top of the figure, P ₁ + P ₃ -2 · P ₂ is calculated, and this value is compared with the threshold given in advance by the comparison unit 14. When the calculated value is larger than the threshold value, it is determined that there is a substrate, and when the calculated value is smaller, it is determined that there is no substrate. This process has the same content as the second derivative process of the first embodiment.
[0036]
In the present embodiment, the determination means 6 ″ is constituted by the hardware of the calculation unit 15 and the comparison unit 14. However, as in the embodiment of FIG. May go.
[0037]
Although a three-divided light receiving element is used here, for example, a five-divided light receiving element is used, and the outputs of the light receiving units are set to P ₁ , P ₂ , P ₃ , P ₄ , and P _{5 to} be 16 · P ₂ +16. By calculating P ₄ −P ₁ −P ₅ −30 × P ₃ , the accuracy of the second derivative can be improved.
[0038]
By using a multi-divided light receiving element as in the present embodiment, the size of the sensor unit can be reduced as compared with arranging the light receiving elements as in the second embodiment.
[0039]
【The invention's effect】
According to the present invention, the following effects can be obtained.
(1) The thin substrate detecting device of the present invention is configured such that an optical condensing unit that condenses scattered light around the thin substrate on a photoelectric sensor, and receives the light condensed by the optical condensing unit and converts the light into an electric signal. Light receiving element that collects light around the end face of the thin substrate before receiving it.The signal of the light receiving element is not affected by the shape or reflectivity of the end face of the thin substrate. It is possible to detect a thin substrate more stably as compared with the above, and it is not necessary to provide a light emitting portion unlike the reflection type sensor, so that it can be formed in a small size.
(2) Further, by arranging a plurality of light receiving elements, a differential value can be calculated based on a difference or a sum between outputs of the respective light receiving elements.
(3) By using a multi-divided light receiving element, the size of the sensor unit can be reduced.
(4) A circuit (hardware) for judging the state of the thin substrate by binarization processing, primary differentiation processing or secondary differentiation processing from output values of a plurality of photoelectric sensors is inexpensive without a CPU. And a high-speed detection device can be realized.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a thin substrate detection device according to a first embodiment of the present invention.
FIG. 2 is a front view of a cassette containing a plurality of thin substrates.
FIG. 3 is a graph showing a relationship between a position of a light receiving element and a received light intensity.
FIG. 4 is a configuration diagram of a thin substrate detection device according to a second embodiment of the present invention.
FIG. 5 is a configuration diagram illustrating a connection state of a determination unit of the thin substrate detection device according to the third embodiment and a photoelectric sensor.
FIG. 6 is a configuration diagram of a two-piece optical element.
FIG. 7 is an explanatory diagram of a conventional substrate detection device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Thin substrate 2 Cassette 3 Light receiving element 4 Optical condensing means 5 Driving means 6 Judgment means 7 Element 8 Light receiving section 9 3 divided optical element 10 Arrow 11 AD conversion section 12 CPU section 13 Operation section 14 Comparison section 15 Operation section

Claims (4)

The thin substrate accommodated in the cassette is detected using a photoelectric sensor that is disposed adjacent to the cassette and is movable in one direction by a driving unit, and the state of the thin substrate is determined from an output signal of the photoelectric sensor by a determining unit. In the thin substrate detection device to be determined,
The photoelectric sensor includes an optical condensing unit that condenses scattered light around the thin substrate, and a light receiving element that receives the light condensed by the optical condensing unit and converts the light into an electric signal. A thin substrate detection device characterized by the above-mentioned. 2. The thin substrate detecting device according to claim 1, wherein the plurality of photoelectric sensors are provided in a line along a moving direction. 2. The thin substrate detecting device according to claim 1, wherein the photoelectric sensor has a divided light receiving element obtained by dividing one light receiving surface into a plurality. The determination means includes a circuit for performing a binarization process, a primary differentiation process, or a secondary differentiation process to determine a state of the thin substrate from output values of the plurality of photoelectric sensors or the photoelectric sensors having the divided light receiving elements. The thin substrate detection device according to claim 2, wherein:

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