JPS6355181B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a reflective television image projection tube, and is particularly designed to significantly reduce the temperature rise of a fluorescent target portion at high output.

In recent years, with the diversification of demands for television receivers, there has been a growing trend toward larger screens. As a means of achieving this increase in size, the cathode ray tube method is considered difficult to increase in size over 30 inches due to cost and weight, whereas the projection tube method overcomes these drawbacks, making it ideal for increasing size. Many methods have been proposed and put into practical use so far. There are two methods for this: the refractive method, in which one or more images are enlarged and projected onto the screen using a refractive lens, and the refractive method, in which the image on the phosphor screen of the projection tube is reflected by a concave mirror, and the spherical aberration of the concave mirror is absorbed by a Schmitt lens or meniscus lens. There are two reflective types that are corrected with a correction lens such as, but recently there has been a tendency to adopt the reflective type because the optical system can have a large F-number.

The size of the fluorescent target surface of this reflective projection tube is extremely small at 2 to 3 inches, while the projection screen surface is large at over 50 inches, which is 20 to 30 in linear magnification. It will be doubled. Therefore, even taking into account the screen gain of the projection screen, the brightness is required to be more than 10 times higher than that of a normal television picture tube. This means that the load on the phosphor screen per unit area due to the electron beam is more than 10 times that of a conventional television picture tube.
In addition to problems such as ion burnout of the phosphor, another problem was the rise in temperature of the phosphor screen. This temperature rise is one of the causes of shortening the lifespan of the phosphor and causing thermal deformation inside the projection tube, limiting the beam current to below a certain value and, as a result, also suppressing the brightness below a certain value. Further, since the use of phosphors is limited to those with good temperature characteristics, it is not always possible to use phosphors with good characteristics such as luminous efficiency.

In addition, with the recent spread of projection television receivers in homes, the current weight and size are too large and undesirable, so there is a growing demand for smaller and lighter devices. A smaller projection tube, that is, a smaller fluorescent target is required, and current heat dissipation means have their limits in order to obtain the same brightness, so measures to prevent the temperature rise of the fluorescent screen are becoming more important.

Conventionally, as a countermeasure against this problem, heat dissipation measures have been put into practical use, such as by coating a phosphor on an aluminum block with good thermal conductivity or by blackening the surface of the surrounding support part. In addition, a method has been proposed in which a heat pipe is used as the support rod of the phosphor screen block to release heat to the outside, but this method only has the effect of lowering the thermal resistance between the support part of the phosphor screen block and the external heat sink, so it has no cooling effect. There are few, and it has not been put into practical use.

In the present invention, the fluorescent target section is made hollow to form a sealed container, which has a heat pipe structure, and by extending this sealed container to the heat sink outside the vacuum tube, the thermal resistance between the phosphor and the external heat sink can be ignored. The purpose of the present invention is to provide a television image projection tube in which the temperature of the phosphor is reduced to a relatively low level and there is almost no rise in temperature of the phosphor.

Hereinafter, the present invention will be explained based on illustrated embodiments.

FIG. 1 is a cross-sectional view of an embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along the line A-O-A' in FIG. In those drawings, the fluorescent target part 1 has cooling support parts 2, 3 and support parts 4, 5, and the cooling support parts 2, 3 have metal body parts 2a, 2b, 3a, 3b and insulator parts 2c, 3c. It consists of Further, the outer wall of the fluorescent target section 1 is coated with a fluorescent substance 6. Here, the interiors of the fluorescent target section 1 and the cooling support sections 2 and 3 are connected to form a sealed chamber 7 that is isolated from the outside, and their inner walls are made of glass fiber or inner wall surfaces as shown by dotted lines. A capillary structure 8 such as a provided slit is attached.

Here, heat sinks 9a and 9b are attached to one ends of the cooling support parts 2 and 3, respectively. 10 is a sealing part 1 for sealing provided at the tip of the cooling support part 2
It is 0. In this embodiment, a concave mirror fixed to the cooling supports 2, 3 and the supports 4, 5 is mounted inside the glass tube 13 via a holder 11, and the cooling supports 2, 3 are connected to the glass tube 13. The portion passing through is sealed with a sealing material 14. Thereafter, a front glass 15 is fitted and its periphery is fixed with a cylindrical band 16, and a Schmitt lens 18 is attached to the front part via a mounting fitting 17.

19 is a deflection yoke, 20 is an electron gun, and 21 is a connecting terminal portion.

In the above configuration, the electron beam emitted from the electron gun 20 collides with the phosphor 6 coated on the outer wall surface of the fluorescent target section 1 to generate fluorescence, thereby forming an image. The light from this image is corrected by a concave mirror 12 and then magnified to form an image on a projection screen (not shown). In this process, part of the energy of the electron beam increases the temperature of the phosphor 6. Next, the fluorescent target section 1
will be explained in more detail.

After the sealed chamber 7, which is the interior of the fluorescent target section 1 and the cooling support sections 2 and 3, is once evacuated,
After a certain amount of a working fluid such as water or chlorofluorocarbon at room temperature is sealed, a sealing portion 10 is used to seal it. Further, since the inner wall surface of the sealed chamber 7 is covered with the capillary structure section 8, the working fluid wets the entire inner wall surface. The pressure in the sealed chamber 7 at this time is the vapor pressure of the working fluid.

Therefore, as the temperature of the phosphor 6 increases, the working fluid in the capillary structure 8 in the sealed chamber 7 is heated through the outer wall of the phosphor target part 1 and begins to evaporate, taking away the heat of vaporization. Therefore, the phosphor 6 is cooled through the outer wall of the phosphor target section 1, and as a result, temperature rise is suppressed. This generated steam spreads into the sealed chamber 7 by diffusion, but since the temperature near the heat sinks 9a and 9b is closest to the outside air temperature, the temperature is the closest during operation, and the steam is condensed in this area. , the working fluid changes from the gas phase to the liquid phase and releases heat of condensation,
This heat is quickly radiated to the outside by the heat sinks 9a and 9b.

On the other hand, the working fluid that has returned to the liquid phase is carried throughout the inner wall of the sealed chamber 7 by the capillary action of the capillary structure section 8.
Naturally, due to evaporation, the working fluid is carried to the inner wall of the back surface of the phosphor 6 where it has been consumed, and evaporates again as the phosphor 6 generates heat, and the phosphor 6 is cooled by the latent heat of vaporization.

By repeating the above cooling cycle, the heat generated by the phosphor 6 is continuously transferred to the heat sinks 9a and 9b, and the temperature of the phosphor 6 is prevented from rising. Thermal resistance can be considered to be almost zero like a general heat pipe, so by making the outer wall of the phosphor coating part thinner and making the heat sink substantially larger, the final thermal resistance can be reduced. can be made very low, the phosphor is sufficiently cooled even with large beam currents, and the temperature rise can be suppressed to a low level.

Further, a high voltage is applied to the electron gun 20 in the fluorescent target section 1, and it is not preferable that the voltage leak to the outside. Therefore, it is necessary to take insulation measures between the fluorescent target section 1 and the heat sinks 9a and 9b, but in this embodiment, insulator sections 2c and 3c made of an airtight insulator such as ceramic are provided, and The insulating structure is achieved by using an insulating material such as glass fiber for the capillary structure 8 on the inner wall of the insulator parts 2c, 3c, or by providing slits in the inner wall of the insulator part 2c, 3c. In addition, since an insulating liquid such as Freon is used as the working fluid, the insulation between the sealed chamber 7 and the heat sinks 9a and 9b is maintained even during the cooling cycle, and high voltage is maintained. It will not leak outside.

As described above, in the television image projection tube of the present invention, since the fluorescent target portion is efficiently cooled, the beam current can be increased compared to the conventional case. Further, since it is possible to use a phosphor that has good characteristics such as luminous efficiency and is resistant to temperature rise, the range of phosphors that can be used is expanded. For the above-mentioned reasons, the brightness can finally be increased, so a conventional large screen can be used even if the screen is downsized, and the projection television image device can be easily made smaller and lighter. In addition, the heat generated inside the glass tube 13 is released to the outside by the fluorescent target section 1 and the cooling support sections 2 and 3, and the heat generated inside the glass tube 13
3, which is advantageous in preventing thermal deformation and the like. Furthermore, by providing a heat sink on the outside of the main body of the projection television image device, heat will not be trapped inside the miniaturized chassis, etc., and the reliability of the components can be improved.

Furthermore, by employing a variable conductance heat pipe structure filled with a working fluid and an inert gas, the temperature of the phosphor screen may be kept constant and the influence of the temperature characteristics of the phosphor may be reduced. In addition, in the previous embodiment, the cooling supports 2 and 3 were provided with dedicated external heat sinks 9a and 9b, but instead, the cooling supports 2 and 3 were connected to a portion with low thermal resistance, for example, a chassis. However, it may also be possible to allow heat to escape.

In order to maintain a high vacuum inside the glass tube 13, the outer wall of the fluorescent target section 1 must be evacuated and a metal that does not easily emit gas must be used. In this case, getter portions may be provided on the fluorescent block portion 1 and the support portions 2, 3, 4, and 5.

Furthermore, it is easy to apply the present invention to a reflection type projection television receiver that does not use a Schmitt lens.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of an embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along the line A-O-A' in FIG. 1... Fluorescent target part, 2, 3... Cooling support part, 2a, 2b, 3a, 3b... Metal body part, 2
c, 3c...Insulator part, 4, 5... Support part, 6...
...phosphor section, 7... sealed chamber, 8... capillary structure section,
9a, 9b...heat sink, 12...concave mirror, 13,
15...Glass tube.

Claims (1)

[Claims] 1 Install an electron gun, fluorescent screen, and reflector inside the vacuum tube,
It is a television image projection tube that is equipped with an aspherical lens such as a Schmitt lens to project an enlarged screen onto an external projection surface, and is isolated from the vacuum tube and the outside air, has a capillary structure inside, and has an internal electrical connection. By coating a part of the outside of a sealed container with a heat pipe structure filled with an insulating working fluid with a phosphor that can be irradiated with an electron beam from an electron gun, a fluorescent target part is formed, and the inside of the sealed container is Another heat radiating part of the outer wall is provided outside and outside the vacuum tube, and a part of the container wall of the sealed container between the fluorescent target part and the heat radiating part is made of an insulator. Television image projection tube.