JPH02160336A - Fluorescent lamp manufacturing device - Google Patents

Abstract

PURPOSE:To intend stabilized quality and enhanced yield in manufacturing fluorescent lamps by previously drying coating liquid on the inner face of a glass tube with hot air at a low temperature into a good condition without spots before proper dry efficiently with hot air at a high temperature. CONSTITUTION:A low-temperature drying furnace 10 previously dries coating liquid on the inner face of a glass tube 3 little by little by giving downflow of hot air at 30-40 deg.C. A high-temperature drying furnace 11 properly dries the coating liquid by blowing hot air at 40 deg.C or more against the glass tube 3 in a tray 4 delivered from the low-temperature drying furnace 10. At this time, as the high-temperature drying furnace 11 is at a separated position from the low-temperature drying furnace 10, the glass tube 3 in which the coating liquid is previously well dried in a dry condition of being stable all times is delivered together with the tray 4 from the low-temperature drying furnace 10 to the high-temperature drying furnace 11. It is thus possible to dry the coating liquid uniformly over the total length of the glass tube and stabilize the quality of a fluorescent film which is formed later.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a manufacturing process in which a coating liquid of a phosphor suspension applied to the inner surface of a glass tube of a fluorescent lamp is forcedly dried by blowing hot air. Regarding equipment.

[Conventional technology]

The formation of a fluorescent film in a fluorescent lamp involves a process of applying a coating liquid of a phosphor suspension to the inner surface of a straight glass tube held approximately vertically, a process of drying the coating liquid on the inner surface of the glass tube, and a process of drying the coating liquid on the inner surface of the glass tube. This is performed in the process of baking the dried coating film, and the work efficiency of this fluorescent film forming process and the quality of the formed fluorescent film, such as the thickness, are greatly influenced by the coating liquid drying process.

In other words, if the coating liquid applied to the inner surface of the glass tube is naturally dried at room temperature, the drying time will be long and it will be difficult to dry the coating liquid sufficiently, resulting in poor quality of the fluorescent film. To dry the coating solution, place it in a glass tube for 3 minutes.
The process uses a hot air drying method that blows hot air at temperatures above 0°C. In this hot air drying method, a straight glass tube with a coating liquid applied to its inner surface is held approximately vertically and sent into a drying oven.
This method blows hot air downflowing inside the drying oven into the glass tube.This type of drying equipment consistently blows hot air at a low temperature of 30° to 40°C into the glass tube inside the drying oven. The drying oven is divided into multiple drying zones, and the temperature of the hot air blown onto the glass tube is increased in stages. In the former type of drying equipment, the coating liquid on the inner surface of the glass tube is gradually dried with low-temperature warm air, leaving the entire surface in good condition, but it takes a long time to completely dry, making it difficult to mass-produce. The furnace requires a long overall length and a large floor area, which increases equipment costs. In this drying device, the temperature of the warm air blown into the glass tube is 60℃.
If the temperature is set as high as 70℃, the drying time will be shortened and the total length of the drying oven can be shortened, but if high-temperature air is blown onto the coating solution on the inside of the glass tube from the beginning, only the surface layer of the coating solution will dry. Poor drying occurs, such as things inside remaining semi-dry. Therefore, in recent years, the latter drying device, which increases the temperature of the warm air blown into the glass tube in stages from 30°C to suppress drying defects caused by rapid drying of the coating solution and shorten the drying time, has received awards. A conventional example thereof will be explained with reference to FIGS. 4 to 6.

In the drying device shown in the figure, (1) is a drying oven, and (2) is a conveyor that passes through the drying oven (1), and a plurality of glass tubes (3) are held approximately vertically on the conveyor (2). A tray (4) is placed. The inner surfaces of the plurality of glass tubes (3) - inserted into the tray (4) are coated with the coating liquid (5) in advance, and the glass tubes (3) ... - are conveyed together with the tray (4). (2) into the drying oven (1).
) Glass tube (3) with warm air downflowing inside
The coating liquid (5)-- is forcedly dried in stages as described below.

The interior of the drying oven (1) is divided into a plurality of drying zones AI, A2, ... along the glass tube conveyance path, and the first drying zone 8L is the longest in the low temperature drying zone, and in this low temperature drying zone A1, the ceiling Air is blown by the blower (6) from the heater (
7) The warm air heated to about 30℃ is downflowed,
This hot air flows through a glass tube (3) held in a tray (4).
- passes directly below the inside and outside of the room and is sucked out from the floor by the exhaust fan (8). While the glass tube (3) passes through the low-temperature drying zone A, warm air at about 30° C. is blown into the glass tube (3) from top to bottom to pre-dry the coating liquid (5). This pre-drying is the drying that most affects the quality of the fluorescent film that will be formed later, so we gradually heat it at a low temperature for a long time so that the coating solution (5) dries to the extent that it does not flow down the inner surface of the glass tube (3). It is carried out by the wind.

The low-temperature drying zone A of the drying oven (1), the subsequent drying i-zones A2, A3, etc. are high-temperature drying zones, for example, divided into three zones, and the first high-temperature drying zone Δ2 has a
℃ warm air is heated to about 50'C in the second high temperature drying zone A3.
In the third high-temperature drying zone A4, warm air of approximately 60°C is downflowed and sucked from the floor. Persons 2 to A4 in this high temperature dry zone are in the low temperature dry zone A.

This zone is for main drying the coating solution (5) of the glass tube (3) whose quality such as narrow thickness has been determined by pre-drying in a shorter time. %
While passing through A4, the coating liquid (5) was first forcedly dried in stages with warm air of about 40°C, then with warm air of about 50°C, and finally main drying with warm air of about 60°C. Ru.

A specific example will be explained. If the glass tube (3) is a 40 watt straight fluorescent lamp, preliminary drying is performed in the low temperature drying zone A of the drying oven (1) for about 20 minutes, and then in the high temperature drying zone A2-84 for about 20 minutes. Main drying was performed for 15 minutes, giving a total drying time of about 35 minutes. On the other hand, if the same glass tube (3) is sent to a drying oven (not shown) with only a low-temperature drying zone of about 30'C warm air and subjected to preliminary drying and main drying, the drying time will be about 60 minutes. Therefore, by providing a high-temperature drying zone after one drying oven, the drying time can be significantly shortened, and the overall length of the drying oven can be shortened accordingly, resulting in lower equipment costs.

[Problem to be solved by the invention]

However, if the inside of the drying oven is divided into a low-temperature drying zone and a high-temperature drying zone, and the coating solution on the inner surface of the glass tube is dried in stages with low-temperature hot air and then high-temperature hot air, dry spots occur and the glass deteriorates. It was difficult to dry the coating solution uniformly over the entire length of the tube, and the quality of the fluorescent film formed later was unstable. The inventor investigated the cause of this problem through various experiments and found that the cause was disturbance of warm air generated between the low temperature drying zone and the high temperature drying zone of the drying oven. That is, for example, in the drying oven (1) in FIG. 4, warm air flows down from top to bottom in a laminar flow in each drying zone 81 to A4, and is held approximately vertically in the tray (4). The glass tube (3) - is controlled so that it flows parallel to the axial direction inside and outside the glass tube (3).However, the higher the temperature, the more the hot air expands during the downflow and the amount of horizontal flow increases, resulting in laminar flow. is disturbed. This turbulence does not adversely affect the film quality etc. in the high temperature drying zones A and -A since the coating liquid (5) has already been pre-dried. Between zones A2, the approximately 40°C hot air from the first high-temperature drying zone A2 flows horizontally as shown by the broken line arrow in Figure 5, and the 30°C warm air flows down in the low-temperature drying zone A. The flow of hot air is disturbed, so that the glass tube (3) in the final pre-drying stage is in the first high-temperature drying zone A.
The tube wall in the direction of , was heated to a higher temperature, and the drying conditions of the coating liquid (5) in the glass tube (3) became non-uniform, and drying spots occurred at this final pre-drying stage.

In addition, in each drying zone A1 to A4 of the drying oven (1), the hot air is made to flow down in a laminar flow with less turbulence, but as the temperature increases, the hot air expands and flows sideways. In the third high-temperature drying zone A4, where the warm air with the highest temperature of about 60° C. flows down,
By the time the hot air at about 60°C reaches the glass tubes (3), it is greatly disturbed, and the temperature has dropped several 10 degrees, causing the coating liquid (5) in the glass tubes (3).・Thermal efficiency in the main drying of
In 4, the hot air blowing power from the ceiling and the suction power from the floor are higher than others, but this is an effective groove, and a large blower with high capacity must be used. There were some inconveniences with the equipment.

The present invention has been made in view of such problems, and includes a coating liquid drying process in which the coating liquid on the inner surface of the glass tube is pre-dried with low-temperature warm air without any unevenness, and then main-drying is carried out efficiently with high-temperature warm air. The purpose is to provide manufacturing equipment for.

[Means to solve the problem]

The present invention is separated into a low temperature drying oven and a low temperature drying oven that pre-dries the coating liquid in the glass tube by blowing warm air at 30'' to 40℃ into the glass tube to the extent that it does not flow down along the inner surface of the glass tube. 40 in the glass tube transported from the drying oven.
The above object is achieved by a manufacturing apparatus equipped with a high-temperature drying oven that blows hot air at a temperature of .degree. C. or higher to dry the coating solution on the inner surface of a glass tube.

In addition, in order to increase the thermal efficiency of hot air in the high-temperature drying oven, the inside of the high-temperature drying oven is divided into multiple drying zones along the glass tube conveyance path. It is desirable to blow high-temperature warm air into the glass tube from the bottom to the top.

[Effect]

By separating the drying oven into a low-temperature drying oven and a high-temperature drying oven, the coating liquid on the inner surface of the glass tube is not affected by the hot air from the high-temperature drying zone of the high-temperature drying oven, and can therefore be pre-dried better. Then, it is main-dried in a high-temperature drying oven.

In addition, if the inside of the high-temperature drying oven is divided into multiple drying zones and the temperature of the hot air in each zone is raised in stages, the hot air in the subsequent drying zone is blown up from the bottom to the top. Due to its high temperature, it naturally expands even if the capacity of the blower is small, and rises along the inside and outside of the glass tube, and there is little temperature drop until it reaches the glass tube, allowing the coating liquid to be dried with high thermal efficiency.

〔Example〕

Examples will be described below with reference to FIGS. 1 to 3.

In the illustrated embodiment, a plurality of glass tubes (3), which are stored approximately vertically in a tray (4), are pre-dried with hot air and then subjected to main drying. The equipment includes a separate low-temperature drying oven (lO) for pre-drying, a high-temperature drying oven (11) for main drying, and both drying ovens (10) (11) together with the tray (4). 3) It is composed of a conveyor (12) that conveys.

The low-temperature drying oven (10) is used to gradually pre-dry the coating liquid (5) on the inner surface of the glass tube (3) by downflowing hot air at 30° to 40°C. ) is equipped with the same equipment as the low temperature drying zone A. In the drawing, the hot air from the low-temperature drying oven (10) is set at 30°C, but depending on the size of the glass tube, hot air slightly raised to 40°C may be used. In addition, this warm air is blown ta as before.
The air from (6) is heated by the heater (7).
It is sucked from the floor of the low temperature drying oven (10) by an exhaust fan (8).

The high-temperature drying oven (11) blows warm air of 40°C or higher onto the glass tubes (3) of the tray (4) transported from the low-temperature drying oven (10) to dry the coating liquid (5). Let the book dry. Since the high-temperature drying oven (11) is located separately from the low-temperature drying oven (10), the high-temperature warm air from the high-temperature drying oven (11) does not affect the drying zone of the low-temperature drying oven (10). From the low-temperature drying oven (10), the glass tube (3), which has been well pre-dried with the coating liquid under always stable drying conditions, is carried into the high-temperature drying oven (11) together with the tray (4).

The specific structure of the high-temperature drying oven (11) is shown in Figs. 2 and 3. The interior is divided into first to third high-temperature drying zones B, CSD along the glass tube conveyance path, and In the first high-temperature drying zone B, warm air of about 40°C is downflowed, in the second high-temperature drying zone C of the middle stage, warm air of about 50°C is downflowed, and then in the first and third high-temperature drying zone The high temperature drying zone D is modified so that warm air at about 60°C flows from the bottom to the top.

To explain in detail, the coating liquid (5) in the glass tube (3) is pre-dried when it is carried into the first high-temperature drying zone B of the high-temperature drying oven (11). The lower part of the tube (3) is in a semi-dry state, and drying it by blowing warm air at about 40° C. from below is premature, which may cause poor drying. Therefore, the first
In the high-temperature drying zone B and the second high-temperature drying zone C, warm air is downflowed to dry the coating liquid (5) at the bottom of the glass tube (3) to about 90%. It is sent to a high-temperature drying zone D, where warm air at about 60° C. is blown from below along the inside and outside of the glass tube (3).

In this way, even if the blowing force from the floor or the suction force at the ceiling is reduced, the 60°C high-temperature warm air will rise through the third high-temperature drying zone D with its natural upward force without disturbing it. , the coating liquid (5) is passed through the inside and outside of the glass tube (3) to dry it. This main drying is carried out quickly and with good thermal efficiency, since hot air with a temperature h close to 60° C. is blown onto the coating liquid (5) at the bottom of the glass tube (3), where drying is delayed the most.

〔Effect of the invention〕

The present invention has the following effects with the above configuration.

1? ? According to the manufacturing apparatus described in claim 1, 2. Because the low-temperature drying oven and the high-temperature drying oven are separated, the preliminary drying of the coating liquid on the inner surface of the glass tube in the low-temperature drying oven is affected by the high-temperature hot air from the high-temperature drying oven. It is always carried out under stable conditions without being exposed to
Therefore, after this pre-drying, the coating solution is dried and baked at °C, and the quality of the fluorescent film is stabilized, which improves the yield of fluorescent lamp manufacturing.

In the manufacturing apparatus according to claim 2, by blowing high-temperature warm air from the bottom to the top of the glass tube in the last drying zone among the plurality of drying zones in the high-temperature drying oven, the lower part of the glass tube is The coating liquid is dried intensively and with high thermal efficiency, which shortens the main drying time.Also, blowing up high-temperature warm air can be easily done even if the suction force of the air blower is reduced, so the blowing mechanical system is Equipment can be made smaller.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing an embodiment of the present invention, FIG. 2 is a longitudinal sectional view of a drying oven for explaining the drying operation sequence in the device shown in FIG. 1, and FIG. FIG. 3 is a side view with a partial cross section of the glass tube in the drying zone; FIG. 4 is a plan view of a conventional fluorescent lamp manufacturing apparatus. , FIG. 5 is a partially enlarged cross-sectional view of the drying oven in the apparatus of FIG. 4, and FIG. 6 is a side view including a partial cross-section of the glass tube in each drying zone of the apparatus of FIG. 4. (3)--Glass tube, (5)--Coating liquid,
(1O)--Low temperature drying oven, (11)--High temperature drying oven, BSC, Il-Drying zone. Figure 1 Figure 2 Figure 4 Figure 5

Claims (2)

[Claims] (1) A manufacturing device that dries the coating liquid by blowing hot air into a straight glass tube that is held approximately vertically and whose inner surface is coated with a coating liquid containing a phosphor, and which is heated at a angle of 30° to 40°. It is separated into a low-temperature drying oven and a low-temperature drying oven, which pre-dries the coating liquid in the glass tube by blowing warm air at ℃ to the extent that it does not flow down along the inner surface of the glass tube.
A fluorescent lamp manufacturing apparatus comprising a high-temperature drying furnace that blows hot air of 40° C. or higher into a glass tube transported from a low-temperature drying furnace to dry the coating liquid on the inner surface of the glass tube. (2) The inside of the high-temperature drying oven is divided into multiple drying zones along the glass tube conveyance path, and at least in the final drying zone of the glass tube conveyance path, high-temperature warm air is directed into the glass tube from bottom to top. Claim 1 characterized in that:
The fluorescent lamp manufacturing apparatus described.