JPH10128201A - Hard substrate coating device and its control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify work and to improve the operation rate of a coating device by circulating a coating liquid supplied to a froth removing level lower than a reference level at the time of coating application to a coating liquid tank between this tank and a circulating pump to completely replace the air in a piping with the coating liquid, then additionally supplying the coating liquid to the coating liquid tank. SOLUTION: The liquid level of the coating liquid vessel 12 is monitored by level sensors 50, 52. When the one level sensor 52 detects the froth removal level L1 , a supply system 30 stops the supply of the liquid and starts a circulation system 34. When the circulating pump 70 starts, the liquid in the coating liquid vessel 12 circulates from a suction port 66 to a discharge port 48. At this time, the liquid passes a filter 72 where air bubbles are captured. This circulation system 34 stops after continuing the operation for the prescribed set time. A control section 78 starts the supply system 30 again and sends the liquid from a coating liquid tank 38 to the coating liquid vessel 12. The supply is stopped when the liquid level attains the reference level L0 . After the liquid is supplied up to the reference level L0 in such a manner, the coating of hard substrates is started.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hard substrate coating apparatus used for manufacturing a liquid crystal display panel or the like using a glass substrate, and a thin substrate coating apparatus for applying a coating liquid such as a photoresist to a hard substrate uniformly. Method and.

[0002]

2. Description of the Related Art In a manufacturing process of a liquid crystal plate, there is a process of applying a coating liquid such as a photoresist to a thin and uniform thickness on a hard substrate such as a glass substrate. For example, in the production of a color liquid crystal plate, a transparent electrode is formed on a glass substrate in advance,
After uniformly applying a red color mosaic liquid having the function of a photoresist, the color mosaic corresponding to the red color is cured by exposure, and an excess liquid is removed to form a red color mosaic. . The same processing is repeated for other colors such as green, blue, black, and transparent. When a coating liquid to be a photoresist is applied as described above, the liquid needs to be strictly controlled to have a uniform thickness (for example, about 1 μ ± 3%) and to be applied thinly. This is because if the thickness of the coating is non-uniform, the light transmittance becomes uneven, which leads to a deterioration in quality.

Conventionally, a spin coater has been used for this coating. In this spin coater, a coating liquid is dropped near a rotation center of a rotated substrate, and the liquid is applied by scattering using a centrifugal force. However, in the method using the spin coater, not only the time and labor efficiency for replacing the substrate are deteriorated, but also the amount of the liquid scattered and discarded increases. For this reason, there was a problem that the cost was increased.

In view of this, it has been considered to use an apparatus for coating a substrate between a pair of upper and lower rollers disposed horizontally. In this device, the lower part of the micro rod bar, which is the lower roller, is immersed in the coating solution, and the substrate is sandwiched between the micro rod bar and the nip roller located above the micro rod bar. It is to be applied.

Here, the micro rod bar is formed by winding a thin metal wire in close contact with the surface of a metal rod having a circular cross section, and applies a liquid by utilizing a capillary phenomenon caused by a groove between the metal wires.

[0006]

This apparatus has a supply system for feeding a coating solution from a tank to a coating solution tank and a circulation system for generating a steady flow in order to prevent the solution in the coating solution tank from stagnating. However, there is a problem that air in the liquid supply pipe and the circulation pipe is mixed with the liquid and bubbles are mixed into the coating liquid supplied to the coating liquid tank. If these bubbles adhere to the coating surface of the hard substrate, they cause coating defects. Therefore, conventionally, when liquid supply and circulation start, the pipe is removed immediately before the coating liquid tank, the coating liquid is discarded in another container until the air bubbles disappear, and the pipe is connected to the coating liquid tank when the air bubbles disappear. Was out. Thus, there is a problem that the operation of removing the pipe and discarding the liquid containing bubbles is complicated, takes time, and lowers the operation rate. There is also a problem that the amount of the coating liquid wasted increases.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has been made in consideration of the above circumstances. The present invention has been made in consideration of the above circumstances, and has been made in consideration of the above circumstances. A first object is to provide a control method of the device.

It is a second object of the present invention to provide a hard substrate coating apparatus used directly for carrying out this method.

[0009]

According to the present invention, a first object is to provide a hard substrate between a micro rod bar whose lower part is immersed in a coating solution tank and a nip roller facing above the micro rod bar. In the control method of the hard substrate coating apparatus that applies the coating liquid to the lower surface of the hard substrate by sandwiching and sending,
The coating solution is supplied to the coating solution tank from a discharge port slightly higher than the bubble removal level up to the bubble removal level lower than the reference level at the time of application, and the air in the pipe of the coating solution supply system is replaced with the coating solution. The coating liquid in the coating liquid tank is circulated between the circulating pump and the air in the piping of the circulation system is completely replaced with the coating liquid, and then the coating liquid is additionally supplied to the coating liquid tank to reach the reference level. And a method for controlling a hard substrate coating apparatus.

In this case, since the liquid level in the coating liquid tank is at a position lower than the discharge port, the air in the pipe is mixed with the liquid in the coating liquid tank and easily diffused into the air without generating bubbles. Only the coating liquid is discharged into the coating liquid tank.

A second object of the present invention is to feed a hard substrate between a micro rod bar whose lower part is immersed in a coating solution tank and a nip roller facing above the micro rod bar. In a hard substrate coating apparatus that applies a coating liquid to the lower surface of a hard substrate, a supply system that supplies the coating liquid to the coating liquid tank, and the coating liquid in the coating liquid tank is foamed at a reference level at the time of application and lower than this A level sensor for detecting that the liquid is at the draining level, a circulation system for circulating the coating liquid in the coating liquid tank while supplying the coating liquid from the discharge port slightly higher than the bubble releasing level to the coating liquid tank, While replacing the air in the piping of the system with the coating liquid, the coating liquid is supplied to the bubble removal level, the coating liquid is circulated while the air in the piping of the circulating system is replaced with the coating liquid, and the bubble is removed before coating. Reference level when applying liquid In hard substrate coating apparatus, characterized in that it comprises an additional supply control unit is achieved by.

Here, two level sensors can be provided, each of which detects a reference level at the time of application and a bubble removal level. In this case, the detection of the liquid level becomes very accurate. However, since it is not necessary to manage the bubble removal level with high accuracy, the bubble removal level sensor may also be used as a level sensor for detecting the reference level at the time of application.

It is desirable to provide an antifoaming means for capturing and eliminating air bubbles in the circulation system. For example, it is possible to provide a filter for the coating liquid in the circulation system, and to capture and eliminate bubbles in the filter.

[0014]

FIG. 1 is an overall layout view of an embodiment of the present invention, FIG. 2 is a perspective view of a main part thereof, FIG. 3 is a control system diagram, and FIG. 4 is a flow chart of operation.

In FIGS. 1 and 2, reference numeral 10 denotes a glass substrate used for a color filter of a liquid crystal plate, which serves as a hard substrate. The glass substrate 10 has a width of, for example, 300 to 7
It is 00 mm, 400-900 mm in length and 0.7 mm in thickness.

Reference numeral 12 denotes a coating solution tank, and 14 denotes a micro rod bar. The micro rod bar 14 is formed by winding a thin metal wire tightly around the surface of a rod having a circular cross section, and applies a liquid by utilizing the capillary phenomenon caused by a groove between the metal wires. The micro rod bar 14 is driven by a motor while being mounted on a backup material 16 provided in the coating liquid tank 12.

The liquid surface of the coating liquid 18 is controlled to be constant so that the lower part of the micro rod bar 14 is sufficiently immersed. The outer diameter (diameter) of the micro rod bar 14 is about 6
１２12 mm. A nip roller 20 is rotatably held above the micro rod bar 14 while maintaining a predetermined gap.

The glass substrate 10 is conveyed from the left side in FIG. 8 with both left and right edges placed on conveyance rollers, and its front edge enters between the micro rod bar 14 and the nip roller 20. Thereafter, the liquid is fed to the right side at a constant speed by the rotation of the nip roller 20 and the micro rod bar 14, and the liquid is applied to the lower surface of the glass substrate 10 by the micro rod bar 14 during that time.

In FIGS. 1 and 2, reference numeral 22 denotes a conveying roller, which contacts only the lower surfaces of the left and right edges of the glass substrate 10. The transport roller 22 is driven by a drive mechanism housed in a case 24 shown in FIG. 2, and transports the glass substrate 10 at a constant speed.

The micro rod bar 14 is held horizontally so that its upper part is exposed from the liquid. The intermediate portion of the micro rod bar 14 is supported from below by the backup member 16 shown in FIG. The backup member 16 is made of a hard synthetic resin having excellent slidability, and a semicircular groove formed on the upper surface thereof along the longitudinal direction abuts against the micro rod bar 14 from below, and the micro rod bar 14 To prevent deflection.

One end (the end on the rear side in FIG. 1) of the micro rod bar 14 projects rearward from the coating solution tank 12, and this projecting end is connected to an electric motor (not shown) by a detachable joint. The rotation of the electric motor is also transmitted to the transport roller 22 so that the feed speed of the glass substrate 10 is equal to the transport speed of the transport roller 22.
The surface of the nip roller 20 is made of conductive rubber, and is held so as to apply a predetermined clamping force to the glass substrate 10 with the glass substrate 10 sandwiched between the nip roller 20 and the micro rod bar 14.

Next, a supply system 30 for supplying the coating liquid to the coating liquid tank 12, a drainage type 32, a circulation system 34, and a solvent supply system 3
6 will be described. The supply system 30 sends the coating liquid adjusted to a predetermined concentration from the coating liquid tank 38 to the coating liquid tank 12. That is, the coating liquid tank 38 is made airtight, and the inside thereof is pressurized to a constant pressure by the air pump 40 to pump the coating liquid.

Reference numeral 42 denotes a liquid sending valve, 44 denotes a filter, 46
Is a ball valve. The supply system 30 includes a valve 42,
By opening 46, the coating liquid is guided from the tank 38 to the coating liquid tank 12. Here, the discharge port 48 in the coating liquid tank 12 of the supply system 30 is horizontally opened from one end of the coating liquid tank 12 toward the other end.

The height of the discharge port 48 is located near a lower defoaming levels L ₁ than the reference level L ₀ at the time of application. These reference level L ₀ and bubble removal level L ₁ are detected by optical level sensors 50 and 52, respectively.

The drainage system 32 has an overflow tube 56 for guiding the application overflowing the reference level L ₀ to the drainage tank 54, and a drainage for draining the liquid in the coating solution tank 12 from the bottom by the valve 58 to the drainage tank 54. And a liquid tube 60. The supply system 30 is provided with a drain tube 64 for guiding the liquid from the filter 44 to the drain tank 54 via a valve 62.

The circulation system 34 is provided with a discharge port 48 of the coating solution tank 12.
A tube 68 that connects between the suction port 66 and the discharge port 48 located near the other end far from the outside of the coating liquid tank 12, a circulation pump 70 and a filter 7 provided in the tube 68.
Have two. The pump 70 allows the liquid to flow gently from the discharge port 48 to the suction port 66, and efficiently removes bubbles contained in the liquid by passing through the filter 72.

Although the filter 72 originally removes fine dust in the liquid, it is desirable that the filter 72 also captures bubbles in the liquid. A normal filter or straight filter has such a function. Therefore, it is desirable that the filter 72 be as fine as possible. The circulating system 34 is also operated during the coating operation to generate a quiet steady flow in the coating liquid tank 12,
It may be possible to prevent the concentration of the liquid from becoming uneven at some places due to the stagnant liquid.

The solvent supply system 36 has a solvent tank 74 and a solvent replenishment pump 76, and replenishes the solvent in the coating solution tank 12. That is, since the concentration of the coating solution increases due to evaporation of the solvent during circulation or application in the circulation system 34, the concentration is kept constant by replenishing the solvent from the solvent supply system 36 in a timely manner.

Reference numeral 78 denotes a control unit, and the level sensor 50,
52 and all valves and pumps are connected, and are controlled according to a predetermined operation program.
Next, an operation example of the control unit 78 will be described with reference to FIG.

First, the control unit 78 supplies the coating liquid to the coating liquid tank 12 by the supply system 30 (step 10 in FIG. 4).
0). That is, the inside of the coating liquid tank 38 is pressurized by the air pump 40, the valves 42 and 46 are opened, and the liquid is sent to the coating liquid tank 12.

The liquid level of the coating liquid tank 12 is monitored by the level sensor 50, 52 (step 102), the supply system 30 and its one level sensor 52 of detecting a defoaming level L ₁ stops the supply of the liquid (Step 104). Then, the circulation system 34 is activated (step 106).

When the circulation pump 70 is started, the coating liquid tank 1
The liquid in 2 circulates from suction port 66 to discharge port 48 via tube 68. At this time, the liquid passes through the filter 72, where air bubbles are captured. For this reason, bubbles contained in the liquid flowing out from the discharge port 48 almost disappear or are significantly reduced.

The circulating system 34 stops operating after continuing to operate for a predetermined set time T ₀ (step 108). This set time T ₀ is determined by experiment and stored in memory.

Next, the control unit 78 activates the supply system 30 again, and sends the liquid from the coating liquid tank 38 to the coating liquid tank 12 (step 110). The liquid level to stop the supply and the reference level L ₀ (Sutepu 112). At this time, it is detected by the reference level sensor 50. After the liquid is supplied to the reference level L ₀ in this manner, the application of the hard substrate 10 is started (Step 114).

[0035]

[Other Embodiments] In this embodiment, a filter 72 is interposed in the circulating system 34 and used as a means for capturing air bubbles. However, the present invention may incorporate capture means using another air trap or the like. Further, even if the filter 72 or the capturing means is omitted, the effect of the present invention can be obtained. Therefore, the present invention includes those without these.

The liquid level is determined by two level sensors 50, 5
If the reference level L ₀ and the bubble removal level L ₁ are separately detected in 2, it is desirable that the detection accuracy is high. But since the detection of the bubble removal level L ₁ need not be highly accurate, the bubble removing level using the sensor 50 of the reference level L ₀ L ₁
May also be detected.

[0037]

FIG. 5 is a conceptual diagram of another embodiment, and FIG. 6 is a flowchart showing the operation thereof. In FIG. 5, for simplification of the drawing, a part such as a drainage system is omitted. The same parts as those in the above-mentioned figures are denoted by the same reference numerals, and therefore, description thereof will not be repeated.

The liquid level sensor 50A used here can detect, for example, four liquid level levels L _L , L _H , L ₀ ′, and L ₀ .
L ₀ is a reference level at the time of application, L ₀ ′ is a slightly lower level, L _H is a bubble removal upper limit level, and _LL is a lower bubble removal lower level.

[0039] First feed from the tank 38 by opening the supply system of the valve 46 to the coating liquid in the coating liquid tank 12 (step 200 in FIG. 6), to defoaming upper limit level L _H (step 202). At this time, the air in the pipe of the supply system 30 is completely discharged and replaced with the coating liquid. When this level L _H stopping the supply of the liquid (step 204), starting the circulation pump 70 (Step 206). By starting the pump 70, the air in the piping in the circulation system 34 is discharged.

As the air in the coating liquid is discharged, the liquid level decreases. Once the liquid level within defoaming lower limit level L _L (step 208), the supply system is again activated (step 200), the liquid level to defoaming upper limit level L _H (step 202).

If such operations are repeated and the air contained in the circulation system is reduced, the decrease in the liquid level during circulation is reduced. Therefore predetermined time (30 minutes or more is preferable) without liquid level drops to defoaming lower limit level L _L When elapsed (step 210), debubbling is assumed ended.
Then, the supply system 30 is activated to add the coating liquid (step 212). When the liquid level reaches the level L ₀ ′ (step 214), the supply of liquid is switched to intermittent supply (step 216).

The intermittent supply is performed by, for example, 1 to prevent the liquid level from becoming higher than the reference level L ₀ by continuously supplying the liquid.
Stop supplying for 2 seconds after supplying liquid for 2 seconds. The liquid level in the coating liquid tank 12 is made uniform while the supply is stopped, so that the liquid level sensor 50A can detect the liquid level correctly. Once this way in the intermittent supply is liquid level during coating reference level L ₀ (step 208), it stops the supply of the liquid, for starting the application to the glass substrate 10 (step 220). Note how this intermittent supply, the liquid to can be employed in process of supplying step 200 and 202 until the debubbling upper limit level L _H.

[0043]

According to the first aspect of the present invention, as described above, since the coating liquid filled to the bubble removal level lower than the reference level is circulated by the circulation pump to automatically remove bubbles, the work efficiency is good and the work can be carried out. Extremely simple. For this reason, the operation rate of the device is improved. Further, since it is not necessary to discard the liquid containing bubbles, the liquid is not wasted.

According to the second aspect of the present invention, there is provided a hard substrate coating apparatus directly used for carrying out this method. Here, if the level sensor for detecting the reference level also functions as the level sensor for detecting the bubble removal level, the number of components is desirably reduced. It is desirable to provide a trapping means for removing air bubbles in the circulation system (claim 4). This capturing means can be, for example, a filter for removing minute dust in the liquid.

[Brief description of the drawings]

FIG. 1 is an overall layout view of an embodiment of the present invention.

FIG. 2 is an enlarged perspective view of the application section.

FIG. 3 is a control system diagram

FIG. 4 is a flowchart of the operation.

FIG. 5 is a conceptual diagram of another embodiment.

FIG. 6 is a flowchart of the operation.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 Glass substrate (hard board) 12 Coating liquid tank 14 Micro rod bar 20 Nip roller 30 Supply system 32 Drainage system 34 Circulation system 36 Solvent supply system 50, 50A, 52 Level sensor 70 Circulation pump 72 Filter 78 as a capture means 78 Control unit L ₀ reference level L ₁ bubble removal level L _H bubble removal upper limit level L _L bubble removal lower limit level

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masafumi Ozaki 1005 Koizono, Ayase City, Kanagawa Prefecture Inside Fuji Mike Logigraphics Corporation (72) Inventor Toshiyuki Fujikura 1005 Koizono, Ayase City, Kanagawa Prefecture Fuji Mike Logigraphics Corporation (72) Inventor Masao Otsu 1005 Kozono, Ayase City, Kanagawa Prefecture Fuji Micrographix Co., Ltd.

Claims (4)

[Claims] 1. A hard substrate is sandwiched between a micro rod bar whose lower part is immersed in a coating solution tank and a nip roller opposed to and disposed above the micro rod bar, and is sent to the lower surface of the hard substrate. In the method for controlling a hard substrate coating apparatus for applying a coating liquid, a coating liquid is supplied to the coating liquid tank from a discharge port slightly higher than the bubble removal level to a bubble removal level lower than a reference level at the time of coating. After replacing the air in the piping with the coating liquid, the coating liquid in the coating liquid tank is circulated between the circulating pump and the air in the piping of the circulation system is completely replaced with the coating liquid. A method for controlling a hard substrate coating apparatus, characterized in that a coating liquid is additionally supplied to a liquid tank to make the reference level. 2. A hard substrate is sandwiched between a micro-rod bar whose lower part is immersed in a coating liquid tank and a nip roller facing above the micro-rod bar, and is sent to the lower surface of the hard substrate. In a hard substrate coating apparatus for applying a coating liquid, a supply system for supplying the coating liquid to the coating liquid tank, and detecting that the coating liquid in the coating liquid tank is at a reference level at the time of coating and a bubble removal level lower than this. A level sensor, a circulating system for circulating the coating liquid in the coating liquid tank while supplying the coating liquid into the coating liquid tank from a discharge port slightly higher than the bubble removal level, and an air in the pipe of the supply system. Supplying the coating liquid up to the bubble removing level while replacing the coating liquid, circulating the coating liquid while replacing the air in the circulating system piping with the coating liquid and removing bubbles, and then applying the coating liquid to the reference level at the time of coating. Additional supply control unit And a hard substrate coating apparatus. 3. A level sensor for detecting a reference level at the time of application also serves as a level sensor for detecting a bubble removal level.
Hard substrate coating equipment. 4. The hard substrate coating apparatus according to claim 2, wherein the circulating system has defoaming means for capturing bubbles contained in the coating liquid.