JPH07120507B2 - Fluorescent film dryer - Google Patents

Description

The present invention relates to a drying device used in a step of forming a fluorescent film of a color picture tube.

[Conventional technology]

In a color picture tube, each color such as blue, green,
Each red fluorescent film pattern is painted with a predetermined positional relationship, and a predetermined space is provided from this fluorescent film,
A color selection electrode such as a shadow mask or an aperture grill is attached so that the electron beams corresponding to blue, green and red are projected onto the fluorescent film patterns of the corresponding colors on the fluorescent film.

As a general method of forming a fluorescent film pattern of such a color picture tube, after cleaning the inner surface of the panel, usually, undercoating, polyvinyl alcohol is used as a main component in order to have adhesive strength between the panel and the phosphor. After applying the above liquid, it is dried and polyvinyl alcohol and a dichromate that imparts photosensitivity to it and causes a crosslinking reaction by exposure, for example, ammonium dichromate, and a blue phosphor powder. Apply phosphor slurry mixed with
Dry to make a uniform film. This film is exposed through a shadow mask to cause a crosslinking reaction at a position corresponding to the blue electron beam, and a blue fluorescent film pattern is formed at the exposed position by development. By repeating such operations, green and red phosphor film patterns are sequentially formed in a predetermined arrangement.

When the phosphor film is formed by the above method, it is important that the phosphor layer is uniformly dried in the drying step after coating. For example, if the dryness becomes too strong, the development process in the next step cannot be performed well, the dots or stripes forming the fluorescent film pattern are not separated, and so-called fog development occurs. Alternatively, there is a problem that development occurs in which stripes fall and a part of the fluorescent film pattern is lost. In order not to cause such a problem, it is necessary to keep the drying constant after applying the phosphor slurry.

Conventionally, as a heat source for drying after applying such a phosphor slurry, a far infrared heater 9 is used as shown in the block system diagram of FIG. 4, arranged in a plurality of positions for each color, and at each position. By setting the percentage timer 15 to 100% for a fixed period of time, for example, 15 seconds, the magnet switch 14 is controlled, the far infrared heater 9 is energized and heated for a set percentage of time, and this is repeated. The above settings were made so that the panel was dried by continuously passing through these drying sections.

[Problems to be Solved by the Invention]

The conventional drying device described above controls the degree of heat generation by repeating the energization and cutoff signals from the control power source, and the performance deviation of one or one far-infrared heater element installed at each position, That is, a difference occurs in the surface temperature due to the deviation of the electric resistance value of the element. As a result, the radiant energy from the heater applied to the panel becomes unstable.

[Means for Solving the Problems]

The present invention against the above problems, such as to eliminate the disadvantage of instability of drying, in order to give a uniform radiant energy to the panel coated with the phosphor slurry passing through the drying device, For the far-infrared heater elements distributed and installed at multiple positions, a temperature detector is provided in contact with the surface of each heater element.
and a control unit for controlling the surface temperature of the heater element to a constant value.

The relationship between infrared radiation intensity, spectral distribution and temperature is Pl
It is expressed by the law of ank. That is, Where W _λ is per unit area, per unit wavelength interval,
Is the radiation dose emitted (W / cm ² ), T is the absolute temperature of the radiator (° K), λ is the wavelength of the emitted radiation (cm),
C ₁ and C ₂ are constants.

As a result, by keeping the surface temperature T of each heater element at a desired constant value, W _λ and the radiation dose become constant, and stable drying is performed.

〔Example〕

 Next, the present invention will be described with reference to the drawings.

FIG. 1 shows a fluorescent film coating apparatus 1 according to an embodiment of the present invention.
It is a perspective view of a part. In FIG. 1, a carrier 6 that is suspended by an upper rail 1, a lower rail 2, and a thrust rail 3 and that mounts a panel on a continuous chain 4 is rotatable and runs along a lead rail 8 around an inclined fulcrum 7. hand,
It is installed so as to incline and intermittently moves under a certain cycle time.

FIG. 2 shows a heater unit installed opposite to the stop position of the carrier 6 of the coating apparatus, which has a plurality of far-infrared heater elements 9 and a surface temperature detector 10 attached to each element. There is.

FIG. 3 is a block system diagram of the controller, in which the PID control unit 12 operates due to the difference between the reference temperature set by the heater element surface temperature setting device 11 and the surface temperature detector 10 of the heater element, and the power supply is turned on. Send a signal to unit 13,
The heater element is energized so that the difference between the detected temperature and the set temperature of the setter becomes zero, and the surface temperature of the heater element is controlled so as to maintain the set temperature of the setter.

〔The invention's effect〕

As described above, the present invention makes the surface temperature of the heater element that generates far infrared rays for drying the photosensitive fluorescent film made of the photosensitive phosphor slurry applied to the inner surface of the panel constant, thereby A certain amount of radiation is given to the photosensitive phosphor film of the panel, the difference in drying of the phosphor film between panels can be reduced, a high quality phosphor film can be formed, and the stabilization of the process can be achieved. The effect of improving the yield and yield is great.

[Brief description of drawings]

FIG. 1 is a partial perspective view of an example of a fluorescent film coating apparatus according to an embodiment of the present invention, FIG. 2 is a perspective view of a heater unit of an embodiment of the present invention, and FIG. 3 is an embodiment of the present invention. FIG. 4 is a block system diagram showing the control system of FIG. 4, and FIG. 4 is a block system diagram of a conventional drying device. 1 ... Top rail, 2 ... Bottom rail, 3 ... Thrust rail, 4 ... Chain, 5 ... Panel, 6 ... Carrier, 7 ... Inclination fulcrum, 8 ... Lead rail, 9 ... Heater element , 10 …… Surface temperature detector, 11 …… Surface temperature setter, 12 …… PID control unit, 13 …… Power supply unit.

Claims (1)

[Claims] 1. A heater which is stopped at a predetermined position to dry a photosensitive fluorescent film made of a photosensitive phosphor slurry applied to the inner surface of a panel mounted on a carrier which moves intermittently, and which faces the predetermined position. In a drying device for a color picture tube fluorescent film in which a unit is fixedly arranged, the heater unit includes a plurality of far-infrared heater elements for irradiating a drying far-infrared ray on a coating phosphor surface of the panel moved to the predetermined position, A detector that detects the surface temperature of each heater element, a reference temperature setter, and a control unit that compares the temperature detected by the detector with the reference temperature to keep the surface temperature of the heater element constant. And a heater element surface temperature control device including the same.