JPH10318736A - Automatic gap control head for detection of foreign matter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an automatic gap control head which can enhance the detecting accuracy of a foreign matter without lowering the detecting efficiency of the foreign matter by a method wherein a ring-shaped back pressure face is formed around an air blowoff port and a pressure release groove by which the blown-off air is set free is formed in the outer circumference of the back pressure face. SOLUTION: While the air is being blown off onto a glass substrate (w) from an air blowoff port 3, an automatic gap control head 10 used to detect a foreign body is scanned on the glass substrate (w). The air is reflected by the surface of the glass substrate (w), and a back pressure is generated on a back pressure face 6. The area of the back pressure face 6 is small, and the very small pressure of the air is detected. The blown-off air is received by a pressure release groove 8 so as to be released, and it is set free to the outside of a gap from an air relief groove 7. Therefore, the detecting accuracy of the back pressure is enhanced, the position of a detecting head 1 is controlled by a gap servo control part, and a foreign matter on the glass substrate (w) can be detected precisely. When a foreign matter having a size of 15 μm or higher exists on the substrate (w), the foreign mater is guided by an introduction groove 1e so as to creep into the lower part of the head 1, the gap between the substrate (w) and the head 1 is expanded, and the foreign matter is detected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic gap control head for detecting foreign matter on a glass substrate for non-contact detection of foreign matter attached to the surface of a glass substrate used for a display.

[0002]

2. Description of the Related Art In general, a liquid crystal display has an electrode substrate on which a transparent electrode and a transistor are formed on one side of a glass substrate, and then forms a liquid crystal layer thereon, and further forms a color on one side of the glass substrate from above. It is manufactured by sandwiching it between panel substrates on which filters are formed, and after the manufacture, a final inspection is performed to ensure that all transistors operate correctly.

[0003] This electrode substrate is formed by sputtering a metal material such as a conductive layer, an insulating layer and a Si thin film on the surface of a glass substrate. (Sputtering material) may adhere to generate projection-like foreign matter.

If the projection-like foreign matter adheres to the glass substrate, a defect occurs in the electrical contact and the transparent electrode does not work as an electrode. Not only eventually becomes a defective product, but also when the height of the projecting foreign matter is, for example, 15 μm or more in the operation inspection (final inspection) of the transistor, the foreign matter is present in the inspection section of the final inspection device. There is a possibility that damage such as damage to the inspection apparatus itself due to contact may occur.
Therefore, in order to prevent such damage beforehand, the entire surface of the glass substrate is inspected at high speed and in a non-contact manner,
It is necessary to prevent the glass substrate to which the foreign matter has adhered from being passed to the processes after the sputtering.

Accordingly, the present inventors have previously invented a foreign substance inspection apparatus for a glass substrate and filed an application as Japanese Patent Application No. 9-27779.

This foreign substance inspection apparatus for a glass substrate is provided so as to be capable of moving forward and backward with respect to the surface of the glass substrate, and has an automatic gap control head for foreign substance detection in which an air sensor and a gap servo control means are provided in a detection head. Projection detecting means for detecting that the automatic gap control head has climbed onto the projection and judging the projection.

[0007] When detecting foreign matter, air is injected to the surface of the glass substrate by an air sensor to detect back pressure, and the gap servo control means uses the detected value to determine the gap between the detection head and the surface of the glass substrate. Is scanned over the glass substrate by the detection head while the gap servo control unit generates a control error during scanning, and the projection detection unit determines the projection on the glass substrate.

[0008]

By the way, in order to improve the detection accuracy of foreign substances in this foreign substance inspection apparatus, it is necessary to accurately detect a pressure change due to a change in the gap between the detection head and the glass substrate. It is conceivable to increase the sensitivity of the air sensor by forming the detection head small.

However, if the detection head is made small, the area for scanning on the glass substrate also becomes small at the same time, so that the problem that the detection efficiency of foreign matter is reduced and the inspection cost is increased is expected. You.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an automatic gap control head for foreign substance inspection which can improve the foreign substance detection accuracy without lowering the foreign substance detection efficiency.

[0011]

According to a first aspect of the present invention, air is jetted from an air outlet formed in a detection head to the surface of a glass substrate, and the surface of the glass substrate is subjected to back pressure. In the automatic gap control head for detecting foreign matter, an annular back pressure surface is formed around the air outlet, and a pressure release groove for releasing the blown air is formed on the outer periphery of the back pressure surface. is there.

According to a second aspect of the present invention, the detection head includes:
An air escape groove for allowing air to escape from the pressure release groove other than the surface of the detection head is formed.

According to the above configuration, the air jetted from the air outlet is received by the back pressure surface having an area sufficiently smaller than the surface of the detection head, so that the sensitivity of the air sensor is improved.
Further, the air jetted onto the glass substrate is released outside the gap by the air escape groove, so that the air does not affect the back pressure. As a result, a minute pressure change can be accurately detected, and the detection accuracy of foreign matter is improved.

[0014]

Next, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 2 is a schematic view of an automatic gap control head for detecting foreign matter according to the present invention.

As shown in FIG. 2, an automatic gap control head 10 for detecting foreign matter is a detection head 1 which is scanned while maintaining a predetermined gap with respect to a glass substrate w as a work.
A proper gap detecting means 30 for detecting a gap between the detection head 1 and the glass substrate w by a change in air pressure, and a gap servo control unit 20 for controlling the gap by moving the detection head 1 from the detected value of the gap. It is mainly composed.

The gap servo control unit 20 includes a linear actuator 12 for moving the detection head 1 in a direction perpendicular to the glass substrate w. The linear actuator 12 moves the detection head 1 to a desired position. Has become.

The linear actuator 12 includes a cover 1
The housing 14 is housed in a housing 14 so as to be retractable upward by a pressing spring 17, and presses the detection head 1 downward by a linear shaft 13. The detection head 1 is guided by a linear guide 16 formed on a housing 14 to move in a direction perpendicular to the glass substrate w, and the upper surface of the detection head 1 is pulled from the housing 14 via a pull spring 15 to the lower end of the linear shaft 13. It is supported so that it always comes into contact with.

The linear actuator 12 is composed of an AC servomotor having a home sensor (not shown) and an encoder 11, and the linear shaft 13 moves forward and backward by the forward and reverse rotation of the AC servomotor. Position of tip of linear shaft 13 (position of detection head 1)
Is detected by the encoder 11, and the detected value is input to the counter 25 of the gap servo control unit 20, the port 22 for detecting the origin position and the upper and lower limit positions, and the D / A conversion circuit of the gap servo control unit 20 The linear actuator 12 is controlled via 23.

The gap servo control unit 20 includes a CPU (central processing unit) 29 for controlling the linear actuator 12 and detecting protrusions based on the control result. The above-described A / D conversion circuit 21, port 22, D / A The conversion circuit 23 and the counter 25 are connected to the CPU 2 via the bus 27.
9 is connected. The bus 27 receives a command of a reference value such as a set gap from the outside and receives a command from the CPU.
A port 24 for transmitting the control result at 29 to the outside is connected.

The gap servo controller 20 has a port 24
, The linear shaft 13 of the linear actuator 12 is pushed down via the D / A converter 23, and the position of the detection head 1 is controlled based on the count value from the encoder 11 to the counter 25. Detection head 1
However, until the gap with the glass substrate w becomes appropriate, the pressure of the supply line 37 is low. In this state, the gap servo control unit 20 operates until the air sensor signal reaches the set value.
Push down the detection head 1 and set the appropriate gap (about 15μm)
Is reached, the linear actuator 12 is driven to maintain the state.

The appropriate gap detecting means 30 for detecting the gap between the detection head 1 and the glass substrate w
An air outlet 3 provided to face the glass substrate w from the lower surface of the detection head 1 through the inside thereof to inject air toward the glass substrate w, and a back pressure of the air injected toward the glass substrate w is converted into a pressure transformer. It is mainly composed of an air sensor 4 which detects a voltage value with a transducer 5.

The air outlet 3 has a diameter determined by the air pressure set according to the height of the foreign matter to be detected. The air outlet 3 has a CD (clean & dry) air supply line Al. Is supplied to the surge tank 35, and the filter 3
3. Air at the set pressure is supplied from a supply line 37 to which the regulator 31 is connected. Further, the above-mentioned pressure transducer 5 is connected to the supply line 37, and the pressure transducer 5 detects a pressure change of the supply line 37 as a gap. The signal detected by the pressure transducer 5 is transmitted to the gap servo controller 2
0 is input to the A / D conversion circuit 21.

Next, the detection head 1 will be described in detail with reference to FIG.

FIG. 1 shows a detailed view of the detection head according to the present invention. 1A is a front view, FIG. 1B is a bottom view, FIG.
(C) shows a side view.

As shown in FIG. 1A, the detection head 1
Is formed in a rectangular parallelepiped shape, and the size is small enough to be pushed up by the projection on the glass substrate w.
It is formed as large as possible so as to enhance the foreign substance detection efficiency. In addition, when scanning the glass substrate w with the detection head 1, the outer periphery of the lower surface 1f is obliquely attached to the lower surface 1f of the detection head facing the glass substrate w so that the corner of the detection head 1 is not caught by the foreign matter. And a projection introduction groove 1e is formed.

As shown in FIG. 1B, the above-described air outlet 3 is formed in the center of the lower surface 1f of the detection head 1 through the inside of the detection head 1, and around the air outlet 3 , An annular back pressure surface 6 is formed. The back pressure surface 6 is formed so as to be surrounded by a pressure release groove 8 cut out in an annular shape at a predetermined distance from the outer periphery of the air outlet 3, and the pressure release groove 8 extends from the air outlet 3 to the glass substrate w. The pressure of the air jetted to the outside can be released outside the back pressure surface 6. An air escape groove 7 having a predetermined width and depth is formed on the lower surface 1f of the detection head 1 so as to allow air to escape from the pressure release groove 8 to a portion other than the lower surface 1f of the detection head 1.

As shown in FIG. 1 (c), the air escape groove 7 is formed to have a small width so as to increase the area of the lower surface 1f of the detection head 1 to enhance the efficiency of detecting foreign substances, and to be sufficiently formed. It is formed deep so that air can escape outside the gap. The air escape groove 7 is provided with a pressure release groove 8.
And is formed diagonally along the diagonal line of the lower surface 1f.

FIG. 3 is an enlarged view of the air outlet 3, the back pressure surface 6, and the pressure release groove 8.

As shown in FIG. 3, the pressure release groove 8 is formed to have a narrow width and a deep cutout so as to enhance the foreign substance detection efficiency, and has a capacity capable of sufficiently taking in air and releasing pressure. Have been. Specifically, the capacity of the pressure release groove 8 is formed to be about ten times the cylindrical portion (nozzle) on which the back pressure surface 6 is formed. In terms of diameter, the outer diameter H of the pressure release groove 8 is about (10) ^1/2 times the inner diameter D.

The diameter d of the air outlet 3 is determined from the relationship with the pressure of the air to be jetted, according to the height of the foreign matter to be detected.

FIG. 4 shows the diameter d (d = 0.
5, d = 1) are shown.

As shown in FIG. 4, in order to increase the sensitivity of the air sensor, when the air pressure is set to 1.0 kg / cm ² , the diameter d of the air outlet is formed to be about 0.3 to 0.7 mm. It turns out that it is good.

From the above, the height of the foreign matter to be detected is 1
When the diameter is set to 5 μm or more, the diameter d of the air outlet 3 is set to 0.
Formed to about 3 to 0.7 mm, and set the air pressure to 1.0 k
g / cm ² and the inner diameter D of the pressure release groove 8 is 2.5 to 4 m.
m.

Next, the operation of the foreign matter detection automatic gap control head 10 according to the present invention will be described.

The height of the foreign matter to be detected is about 15 μm or more.

When detecting the projections on the glass substrate w, the automatic gap control head 10 for foreign matter detection scans the glass substrate w while jetting air onto the glass substrate w from the air outlet 3 shown in FIG. I do. The air injected from the air outlet 3 is reflected on the surface of the glass substrate w,
It is received by the back pressure surface 6 and a back pressure is generated. At this time, since the area of the back pressure surface 3 receiving the air is small, a minute pressure change of the air can be detected. After the injected air is received by the pressure release groove 8 and the pressure is released, it is released from the air release groove 7 to the outside of the gap. Thereby, since the air injected to the glass substrate w is not affected by the air after the injection, the detection accuracy of the back pressure is improved. The position of the detection head 1 is controlled by the gap servo control unit 20 based on the detected value thus accurately detected, and the foreign matter on the glass substrate w is accurately inspected.

In this inspection, in the case of a non-defective product having no projection on the glass substrate w, the gap servo control section 20 performs good gap control, and the gap between the detection head 1 and the glass substrate w is maintained properly. Since the pressure of the transducer 5 does not suddenly drop, the CPU 29 regards the glass substrate w as a non-defective product and outputs a non-defective signal from the port 24. In this case, the glass substrate w is not kept strictly flat, has warpage and undulation, and the pressure of the pressure transducer 5 changes according to these undulations. The position of the detection head 1 is controlled so as to maintain the gap appropriately.

On the other hand, 15 μm
When the above foreign matter is present, the foreign matter is guided by the introduction groove 1e of the detection head 1 and enters under the detection head 1. At this time, since the linear actuator 12 in the foreign matter detection automatic gap control head 10 is supported by the push spring 17 so as to be able to retreat, the detection head 1 rides on the protrusion during scanning. This widens the gap between the glass substrate w and the detection head 1, and the air sensor 4 detects a sudden pressure drop.

At this time, in response to a sudden decrease in the pressure of the pressure transducer 5, the gap servo control unit 20 pushes the detection head 1 down to the glass substrate w by projecting the linear shaft 13 of the linear actuator 12 to reduce the gap. Although the control is performed so as to be appropriate, even if the detection head 1 is controlled to be lowered, the detection head 1 is not obstructed by the protrusion and does not fall down. Therefore, there is no position change signal from the encoder 11 and a servo deviation error occurs.

When a servo deviation error occurs, the CPU 29 determines that the servo substrate has climbed onto a projection when a servo deviation error occurs even if the linear actuator 12 is controlled several times even if the linear actuator 12 is controlled several times. A defective signal is output from the port 24.

As described above, according to the present invention, the injected air is received by the pressure release groove 8 and the back pressure is received by the back pressure surface 6 having a small area, so that the sensitivity of the air sensor 4 is improved and the back pressure is reduced. The detection accuracy is improved.

As a result, the detection omission of the foreign substance is reduced, and the detection accuracy of the foreign substance is improved, so that the foreign substance having a desired height can be detected more accurately.

In the present embodiment, the air escape groove 7 is formed on the lower surface 1f of the detection head 1 for ease of manufacture. May be formed. Accordingly, when a plurality of the detection heads 1 are arranged in parallel, the air escape grooves 7 of the respective detection heads 1 do not interfere with each other, so that the air can be more effectively released out of the gap.

The shape of the back pressure surface 6 can be detected most accurately by forming it in an annular shape. However, the shape of the back pressure surface 6 is not limited to an annular shape, but can be changed as appropriate.

[0046]

In summary, according to the present invention, the sensitivity of foreign matter detection can be improved by forming the back pressure surface optimally according to the height of the foreign matter to be detected, and the air escape groove and the pressure release groove can be used. Back pressure detection accuracy can be improved. Thereby, the gap can be controlled more accurately, and the detection accuracy of the foreign matter can be improved.

[Brief description of the drawings]

FIG. 1 is a diagram showing a detection head of an automatic gap control head for foreign matter inspection according to the present invention, wherein (a) is a front view,
(B) is a bottom view and (c) is a side view.

FIG. 2 is a schematic view of an automatic gap control head for foreign substance inspection according to the present invention.

FIG. 3 is a partially enlarged view of a back pressure surface and a pressure release groove formed on the detection head of FIG. 1;

FIG. 4 is a diagram showing air pressure-gap characteristics depending on the diameter of an air outlet.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 detection head 3 air outlet 6 back pressure surface 7 air escape groove 8 pressure release groove 10 automatic gap control head for foreign matter detection 20 gap servo control unit w glass substrate

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Masaru Morita Inside Ishikawajima System Technology Co., Ltd. 1-1-17 Kamiosaki, Shinagawa-ku, Tokyo

Claims (2)

[Claims] 1. An automatic gap control head for detecting foreign matter on a surface of a glass substrate by back-pressure by injecting air from an air outlet formed in a detection head to a surface of the glass substrate. An automatic gap control head for detecting foreign matter, characterized in that an annular back pressure surface is formed around the periphery and a pressure release groove is formed in the outer periphery of the back pressure surface to release the blown air. 2. The automatic gap control head for foreign matter detection according to claim 1, wherein an air escape groove for allowing air to escape from the pressure release groove to a surface other than the surface of the detection head is formed in the detection head.