JP2003303666A - Heating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To aim at lowering of cost, thinning and energy saving of a heater by accurately controlling heating temperature by restraining heating from above a heated object in heating the heated object by radiation heat between heaters arrayed in parallel top to bottom. <P>SOLUTION: A plurality of panel heaters 3 are provided arrayed in parallel with each other with an interval along a vertical direction. Each heater is provided with a heat-radiating body 10a, a top cover 10b covering a top face of the heat-radiating body 10a and a bottom cover 10c covering a bottom face of the heat-radiating body 10a. Heated objects 4 placed between the heaters 3 are heated with heat radiated from the top face side and that radiated from the bottom face side of each heater 3. Emissivity of the bottom cover 10c is set lower than that of the top cover 10b, so that heat radiant quantities from the bottom face side of each heater 3 per unit of time is suppressed than that from the top face side. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating device suitable for heating a flat heating object such as a flat panel display substrate by a plurality of panel-shaped heaters which are arranged in parallel in the vertical direction at intervals. Regarding the device.

[0002]

2. Description of the Related Art In order to efficiently heat an organic thin film formed on a glass substrate, it is effective to heat the film from the inside by infrared heating. In order to perform such infrared heating, a plurality of panel-shaped heaters arranged in parallel with each other at intervals in the vertical direction are provided, and each heater has a heating element and an upper cover that covers the upper surface of the heating element.
A heating target having a lower cover that covers the lower surface of the heating element and disposed between the heaters adjacent to each other is heated by heat radiated from the upper surface side of each heater and heat radiated from the lower surface side. Possible heating devices have been used in the past.

Due to the characteristics of the object to be heated, it may be possible to efficiently heat by suppressing the heating from the upper side and promoting the heating from the lower side. For example, when the thin film on the substrate is heated from above, the surface of the thin film is dried first, and volatilization of the solvent and the like from the inside of the thin film is hindered, which causes deterioration of the film quality and defects. In such a case, the heating target heated by the heating device is heated by the heat radiated from the lower surface side of the heater located above and the heat radiated from the upper surface side of the heater located below. Therefore, it is necessary to suppress the heat radiation from the lower surface side of each heater more than the heat radiation from the upper surface side. Therefore, conventionally, a function of cooling or insulating the lower surface side of each heater has been added.

[0004]

When the cooling function and the heat insulating function are added to each heater, not only the heater becomes expensive, but also the vertical dimension of the heater becomes large. Further, when the object to be heated is large, the heat radiation area of the heater also becomes large, so that the vertical dimension of the heater also becomes large in order to prevent the heater from bending due to its own weight. However, when the vertical dimension of the heater becomes large, the heating device becomes large and energy saving is hindered. Further, when the heater is bent due to its own weight, the distance between the heat radiating surface and the object to be heated becomes non-uniform, which hinders uniform heating. Furthermore, in the heating region between the heaters adjacent to each other, heat is less likely to escape in the vicinity of the center of the heater than in the vicinity of the periphery, and the uniformity of the temperature distribution deteriorates. An object of the present invention is to provide a heating device that can solve the above problems.

[0005]

SUMMARY OF THE INVENTION The present invention comprises a plurality of panel-shaped heaters arranged in parallel in the vertical direction at intervals, each heater being a heating element and an upper cover for covering the upper surface of the heating element. And a lower cover that covers the lower surface of the heating element, the heating target disposed between the heaters adjacent to each other, the heat radiated from the upper surface side of each heater and the heat radiated from the lower surface side. It is applied to a heating device that can be heated by.

A first feature of the present invention is that the emissivity of the lower cover is made smaller than the emissivity of the upper cover, so that the heat radiation amount from the lower surface side per unit time in each heater is the upper surface side. It is in the point that it is suppressed more than the heat radiation amount from. In this case, it is preferable that the emissivity of the lower cover is smaller than the emissivity of the upper cover due to the difference in surface texture between the lower cover and the upper cover. A second feature of the present invention is that the thermal conductivity of the lower cover is made smaller than the thermal conductivity of the upper cover, so that the heat radiation amount from the lower surface side per unit time in each heater is from the upper surface side. It is in the point that it is suppressed more than the heat radiation amount of. In this case, it is preferable that the thermal conductivity of the lower cover is smaller than the thermal conductivity of the upper cover due to the difference between the material of the lower cover and the material of the upper cover. According to the present invention, without adding a cooling function or a heat insulating function to the lower surface side of each heater, suppress the heat radiation from the lower surface side of each heater than the heat radiation from the upper surface side, lower the cost of the heater, Thinning and energy saving can be achieved.

It is preferable that the heater is supported at both ends by a furnace body, and the coefficient of thermal expansion of the lower cover is smaller than that of the upper cover. This offsets the bending of the heater due to its own weight and the bending of the heater due to the difference in thermal expansion between the upper cover and the lower cover, reducing the bending of the heater without increasing the vertical dimension of the heater and making the heating uniform. Can be achieved.

A space is preferably formed inside the lower cover. As a result, a heat insulating function is added to the lower surface side of the heater without requiring a special component, and the heat radiation amount from the lower surface side per unit time in each heater can be suppressed more than the heat radiation amount from the upper surface side. in this case,
A gas introduction means for introducing a gas having a temperature lower than the set temperature of the heater is provided in the space, and the gas introduced into the space flows from the vicinity of the center of the heater toward the periphery so that the gas of the heater It is preferably introduced near the center. As a result, the temperature distribution in the heater can be made uniform with high accuracy in a short time, and the heating target can be uniformly heated. Further, each heater is provided with a partition wall that divides the space into a chamber near the center and a chamber closer to the periphery than the chamber near the center, and the partition has gas flow holes that connect the adjacent chambers. Is preferably provided, and gas is introduced into the chamber near the center thereof by the gas introduction means. This ensures that the gas flows from the center toward the periphery.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION A heating device 1 shown in FIGS.
The furnace body 2 and a plurality of panel-shaped heaters 3 arranged inside the furnace body 2 are provided. As shown in FIG. 3, the heaters 3 are arranged in parallel with each other at intervals in the vertical direction with the thickness direction as the vertical direction. The flat plate-shaped heating target 4 is supported with the thickness direction being the vertical direction by the support pieces 6 projecting upward from each heater 3. The upper and lower surfaces of each heater 3 and the upper and lower surfaces of the heating target 4 are arranged horizontally.
The heating target 4 is efficiently heated by forming an organic thin film on a glass substrate, such as a flat panel display substrate, suppressing heating from the upper side and promoting heating from the lower side. It is something. In the present embodiment, the heating target 4 is put into and taken out from the entrances that are opened and closed by the opening and closing doors 2a and 2b on both sides of the furnace body 2.

As shown in FIGS. 3 and 4, each heater 3 is mounted on a bracket 5 so that both ends thereof are supported by the furnace body 2. It should be noted that each heater 3 may be fixed to the bracket 5 only at one place so that the deformation due to thermal expansion can be released by a bolt or the like. Each heater 3 includes a thin heating element 10a made of metal foil, mica or the like that generates heat when energized, a plate-shaped upper cover 10b that covers the upper surface of the heating element 10a, and a lower cover that covers the lower surface of the heating element 10a. 10c and. The upper cover 10b, the lower cover 10c, and the heating element 10a are connected by, for example, bolts, and the heating element 10a is connected to the upper cover 10a.
It is sandwiched between b and the lower cover 10c. With this, the heating device 1 can heat the heating target 4 arranged between the heaters 3 adjacent to each other by the heat radiated from the upper surface side and the heat radiated from the lower surface side of each heater 3.

By making the emissivity of the lower cover 10c smaller than that of the upper cover 10b, the heat radiation amount from the lower surface side of each heater 3 per unit time is smaller than the heat radiation amount from the upper surface side. It is suppressed. In the present embodiment, the surface texture of the lower cover 10c and the upper cover 10
Due to the difference from the surface texture of b, that is, the lower cover 10
The emissivity of the lower cover 10c is changed by the difference in properties between the lower surface 10c 'of c and the upper surface 10b' of the upper cover.
It is smaller than the emissivity of. Specifically, the upper surface 10b 'of the upper cover 10b is sandblasted, and the lower surface 10c' of the lower cover 10c is mirror-finished so that the surface area of the upper surface 10b 'is larger than the surface area of the lower surface 10c'. In addition, the upper surface 10 of the upper cover 10b
b'is covered with a coating of high emissivity. The film is formed by, for example, a secondary electrolytic coloring alumite treatment. Further, the emissivity of the lower cover 10c is made smaller than that of the upper cover 10b by forming the space 20 functioning as a heat insulating layer inside the lower cover 10c.
In the illustrated example, the lower cover 10c has upper and lower plate-shaped members 10ca and 10cb which are opposed to each other at a vertical interval, and a peripheral wall extending downward from the peripheral edge of the upper plate-shaped member 10ca and the lower plate-shaped member 10c.
Peripheral walls extending upward from the peripheral edge of cb are fitted together and connected by bolts or the like. The vertical distance between the upper and lower plate-shaped members 10ca and 10cb is, for example, 10 to 14 mm.
It is said that

Further, since the thermal conductivity of the lower cover 10c is made smaller than that of the upper cover 10b, the amount of heat radiated from the lower surface side of each heater 3 per unit time is lower than that of the upper surface. It is suppressed more than the radiation dose. Further, the thermal expansion coefficient of the lower cover 10c is smaller than that of the upper cover 10b. In the present embodiment, due to the difference between the material of the lower cover 10c and the material of the upper cover 10b, the thermal conductivity of the lower cover 10c is made smaller than that of the upper cover 10b, and the thermal expansion coefficient of the lower cover 10c. Is smaller than the coefficient of thermal expansion of the upper cover 10b. Specifically, the upper cover 10b
Is made of aluminum, and the material of the lower cover 10c is made of stainless steel. Note that it is not necessary to make the thermal conductivity of the entire lower cover 10c uniform, and for example, the upper plate-shaped material 10ca
Is made of the same material as the upper cover 10b, and the upper plate member 10c
Lower plate-shaped material 10cb that has a greater effect on the amount of heat radiation than a
The thermal conductivity of may be smaller than that of the upper cover 10b.

As shown in FIG. 5, the space 20 formed inside each lower cover 10c includes a chamber 20a near the center of the heater 3 and a chamber 20b closer to the periphery than the chamber 20a near the center. It is divided by the partition wall 21.
The gas flow hole 2 that connects the adjacent chambers to the partition wall 21
1a is provided.

A gas introduction pipe 22 is provided as a gas introduction means for introducing a gas into each space 20. One end of the gas introduction pipe 22 is connected to a gas supply source (not shown) outside the furnace body 2. The gas introduction pipe 22
The other end of the is branched so as to be inserted into each heater 3,
Each space 20 is arranged in a chamber 20a near the center. As a result, the other end of the gas introduction pipe 22 has a blowout port 22 that blows out gas from near the center of the space 20.
It is a. The gas blown out from the blowout port 22a is introduced into the chamber 20a near the center and then flows through the gas circulation hole 21a as shown by an arrow in FIG. 5 to the chamber 20b adjacent to the periphery. That is, the gas introduced into the space 20 flows from the center toward the periphery. In order to preheat the gas introduced into the space 20, a heater 26 for preheating the gas flowing through the gas introduction pipe 22 is attached to the furnace body 2 as shown in FIG.

In order to discharge the gas introduced into the space 20, the lower plate member 1 of the lower cover 10c of each heater 3 is discharged.
A plurality of outlets 23 are provided at 0cb. Each outlet 23 is close to the periphery of the heater 3. Each exhaust port 23 is arranged at a position closer to the periphery of the heater 3 than the arrangement region of the heating target 4 so that the gas exhausted from each exhaust port 23 is not directly blown to the heating target 4. The number and arrangement of the outlets 23 are not particularly limited as long as the gas introduced into the space 20 can flow from the center of the heater 3 toward the periphery.

In order to guide the gas discharged from the discharge port 23 to the outside of the furnace body 2, exhaust pipes 27 having a plurality of gas inlet holes 27a formed on the outer circumference are provided on both sides of each heater 3. . One end of each exhaust pipe 27 is closed and the other ends are connected to each other and open outside the furnace body 2.
The gas inflow hole 27a of each exhaust pipe 27 is formed at a position facing the outlet / inlet of the furnace body 2, whereby the gas discharged from the outlet 23 is guided toward the outlet / inlet of the furnace body 2. Therefore, when the entrance / exit of the furnace body 2 which is closed by the opening / closing doors 2a and 2b is opened, the outside air is prevented from entering the furnace body 2 through the entrance / exit door by the gas, and the temperature inside the furnace body 2 is controlled. The decrease can be reduced.

The type of gas is not particularly limited as long as it does not affect the object to be heated 4, and for example, nitrogen gas or dry air can be used. The gas flow rate may be appropriately determined according to the scale of the heating device 1 and the set temperature of the heater 3. For example, the size of each heater 3 is 950 mm ×
1140 mm x 38 mm with a parallel pitch of 75 mm-9
When processing 5 heating objects 4 with 0 mm, the gas flow rate is 20 to 100 liters per minute for each heater.
As for the temperature of the gas, for example, the set temperature of the heater 3 is 100 ° C.
If the temperature is set to 180 ° C, the temperature is lowered by about 20 ° C, and if the set temperature of the heater 3 is 180 ° C to 250 ° C, it is preferable that the temperature is lowered by about 30 ° C. No need to preheat.

According to the above embodiment, the heat radiation from the lower surface side of each heater 3 is suppressed more than the heat radiation from the upper surface side without adding the cooling function and the heat insulating function to the lower surface side of each heater 3. It is possible to reduce the cost of the heater 3, reduce its thickness, and save energy. Further, the bending of each heater 3 due to its own weight and the bending of the heater 3 due to the difference in thermal expansion between the upper cover 10b and the lower cover 10c are offset to reduce the bending of the heater 3 without increasing the vertical dimension of the heater 3. However, the heating can be made uniform. Furthermore, a space 20 is provided inside the lower cover 10c of each heater 3.
Therefore, a heat insulating function is added to the lower surface side of the heater 3 without requiring a special component, and the heat radiation amount from the lower surface side per unit time in each heater 3 can be changed from the upper surface side. Can be more suppressed. By introducing a gas having a temperature lower than the set temperature of the heater 3 into the space 20 and causing the gas introduced into the space 20 to flow from the center toward the periphery, heat is dissipated in the vicinity of the center of the arrangement region of the heating object 4. Can be promoted. Therefore, the temperature distribution on the heating surface of the heater 3 can be made uniform with high accuracy in a short time, and the heating target 4 can be heated uniformly. By providing the space 20 in each heater 3, the weight can be reduced as compared with a solid heater. Further, since it is only necessary to provide the gas outlet 22a in the vicinity of the center of the heater 3 and to provide the gas outlet 23 in the vicinity of the periphery, it is possible to implement at low cost without requiring a complicated configuration. In the space 20, the gas flows from the chamber 20a in the vicinity of the center to the chamber 20b in the vicinity of the periphery through the gas flow holes 21a, so that the gas can surely flow from the center to the periphery. further,
Since the gas discharged from the discharge port 23 is not directly blown to the heating target 4, the heating target 4 is heated by the gas.
The temperature fluctuation can be prevented.

The present invention is not limited to the above embodiment. The material of the upper cover 10b and the lower cover 10c is not limited to the above-described embodiment. For example, the upper cover 10b is made of brass (JIS-2801), aluminum nitride or silicon carbide, and the lower cover 10c is plated with stainless steel or mild steel plate. It may be done. Further, the upper cover 10b and the lower cover 10c may be made of the same metal material. For example, the upper cover 10b is made of stainless steel (JI) whose upper surface is covered with an oxide film in order to increase emissivity and thermal expansion coefficient.
S-SUS304) and the lower cover 10c may be made of stainless steel (JIS-SUS304) whose lower surface is mirror-finished to reduce emissivity and thermal expansion coefficient. Further, if the heat radiation amount from the lower surface side per unit time in each heater 3 is suppressed more than the heat radiation amount from the upper surface side, the coefficient of thermal expansion of the upper lower cover and the lower cover may be the same,
In addition, the lower cover does not have to have a space, and the gas introduction means to the space may not be provided.

[0020]

According to the heating device of the present invention, when the object to be heated is heated by radiant heat between the heaters arranged in parallel vertically, the heating of the object to be heated from above is suppressed more than from below. The heating temperature can be controlled accurately,
The cost of the heater can be reduced, the thickness can be reduced, and the energy can be saved. Further, the temperature distribution in the heating region can be made uniform in a short time, and the heating target can be uniformly heated with high accuracy.

[Brief description of drawings]

FIG. 1 is a side view of a heating device according to an embodiment of the present invention.

FIG. 2 is a plan view of the heating device according to the embodiment of the present invention.

FIG. 3 is a side sectional view of a main part of the heating device according to the embodiment of the present invention.

FIG. 4 is a perspective view showing a supported state of a panel heater in the heating device according to the embodiment of the present invention.

FIG. 5 is a plan sectional view of a main part of the heating device according to the embodiment of the present invention.

[Explanation of symbols]

1 heating device 2 furnace body 3 heater 4 heating target 10a heating element 10b Top cover 10c lower cover 20 spaces 20a Room near the center 20b Room closer to the periphery than room near the center 21 partition

Claims (9)

[Claims] 1. A plurality of panel-shaped heaters arranged in parallel in the vertical direction at intervals from each other, each heater including a heating element, an upper cover covering the upper surface of the heating element, and a lower surface of the heating element. In a heating device having a lower cover for covering, a heating object arranged between the heaters adjacent to each other can be heated by heat radiated from the upper surface side and heat radiated from the lower surface side of each heater, By making the emissivity of the lower cover smaller than the emissivity of the upper cover, the heat radiation amount from the lower surface side per unit time in each heater is suppressed more than the heat radiation amount from the upper surface side. A heating device characterized by. 2. The heating device according to claim 1, wherein the emissivity of the lower cover is smaller than the emissivity of the upper cover due to a difference in surface texture between the lower cover and the upper cover. . 3. The thermal conductivity of the lower cover is made smaller than the thermal conductivity of the upper cover, so that the heat radiation amount from the lower surface side per unit time in each heater is the heat radiation amount from the upper surface side. 1 or 2 which is suppressed more than
The heating device according to. 4. A plurality of panel-shaped heaters arranged in parallel in the vertical direction at intervals, each heater comprising a heating element, an upper cover covering the upper surface of the heating element, and a lower surface of the heating element. In a heating device having a lower cover for covering, a heating object arranged between the heaters adjacent to each other can be heated by heat radiated from the upper surface side and heat radiated from the lower surface side of each heater, By making the thermal conductivity of the lower cover smaller than that of the upper cover, the heat radiation amount from the lower surface side per unit time in each heater is suppressed more than the heat radiation amount from the upper surface side. A heating device characterized in that 5. The thermal conductivity of the lower cover is smaller than the thermal conductivity of the upper cover due to the difference between the material of the lower cover and the material of the upper cover.
Or the heating device according to 4. 6. The heater according to claim 1, wherein the heater is supported at both ends by a furnace body, and the coefficient of thermal expansion of the lower cover is smaller than that of the upper cover. The heating device described. 7. The heating device according to claim 1, wherein a space is formed inside the lower cover. 8. A gas introducing means for introducing a gas having a temperature lower than a preset temperature of the heater is provided in the space, and the gas introduced into the space flows from the vicinity of the center of the heater toward the periphery thereof, The heating device according to claim 7, wherein the gas is introduced near the center of the heater. 9. Each heater is provided with a partition wall that divides the space into a chamber near the center of the heater and a chamber closer to the periphery than the chamber near the center, and the partition walls are provided with adjacent chambers. 9. A gas flow hole communicating with the gas flow hole is provided, and gas is introduced into the chamber near the center thereof by the gas introducing means.
The heating device according to.