JPH0139632B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cathode ray tube for a light source suitable for a display device, particularly a giant display device.

Conventionally, huge display devices used for example, electronic display boards at baseball stadiums, advertising images and messages on the roofs or walls of buildings, and information displays on highways, etc., have been made by arranging a large number of light bulbs and selecting them. Since the image was created by blinking, there were many problems.

To give some examples of these, for example, in the case of a light bulb, the light is obtained by the red heat of the filament, so the emitted light is mainly orange or white-orange. For this reason, it has been quite difficult to emit a large amount of blue or green color light from these light bulbs.

In addition, in the case of such a light bulb method, in order to modulate the brightness of each pixel, it is necessary to turn the applied current to the filament on and off or change the applied current, but these methods Light bulbs have an extremely low frequency response of 10 Hz or less, and the problem is that the color of the light emitted changes depending on the applied current, making it difficult to display half-tones or color displays that combine light of any color. It was clear.

Furthermore, with such a huge display device,
Generally, there are many cases in which thousands to tens of thousands of 20 to 40W light bulbs are lined up in a row, and there are many problems such as power consumption and heat generation.

Therefore, it has already been proposed to use a cathode ray tube as a light source for the above-mentioned display device, which can solve these problems.

FIG. 1 is a diagram showing an example of the structure of a conventional cathode ray tube for use as a light source for a large display device. Reference numeral 1 denotes a cylindrical portion constituting a vacuum envelope for maintaining a vacuum inside the tube. This vacuum envelope has a hemispherical face plate portion 3 provided at one end of the cylindrical portion 1. A fluorescent surface 2 is formed on the inner surface of the face plate portion 3. An electron gun 4 is provided within the other end of the cylindrical portion 1 for irradiating the entire surface of the fluorescent surface 2 with an unfocused electron beam 12 emitted at a predetermined divergence angle. The other end of the cylindrical portion 1 is closed by a stem portion 5.
has a stem pin 14 and an inner lead 13 for applying a predetermined voltage to each part of the electron gun 4. 6,
Reference numerals 7, 8 and 9 are a heater, a cathode, a grid and an anode, respectively, constituting the electron gun 4. From this anode 9, a conductive spring 10 and a conductive duct 1
1, a predetermined high voltage is supplied to the luminescent surface 2.

The operation of this cathode ray tube will be explained. first,
A negative potential is applied to the grid 8 with respect to the cathode 7, and a predetermined current is also passed through the heater 6 to heat the cathode 7. After the cathode 7 is sufficiently heated in this state, when the potential of the grid 8 is brought close to the potential of the cathode 7, an electron beam is emitted from the cathode 7 toward the fluorescent surface 2. This electron beam becomes an unfocused electron beam 12 with a predetermined divergence angle (θ) depending on various conditions such as the voltage and relative positions of the cathode 7, grid 8, and anode 9, and irradiates the entire surface of the fluorescent surface 2. and causes the phosphor surface 2 to emit light in a color corresponding to the phosphor.

These cathode ray tubes are used, for example, as shown in FIG. 2, by regularly arranging them with the side with the fluorescent surface facing toward you. Generally, the cathode ray tubes are arranged in such a manner that for every 212 cathode ray tubes that emit green light, there is one cathode ray tube 22 that emits red light and one cathode ray tube 23 that emits blue light. This is because the resolution that governs the clarity of images made up of a collection of light sources made up of these cathode ray tubes is determined by the number of green pixels, and red and blue serve to color this. The inventors quickly confirmed that this theory was correct by creating a giant display with the arrangement shown in Figure 2.

For example, in a system in which a large number of small cathode ray tubes 21, 22, and 23 having monochromatic fluorescent surfaces such as green, red, and blue are lined up to display a desired image, electrical energy is converted into light energy. Not only is the energy conversion efficiency significantly improved compared to light bulbs, but it also has many advantages, such as the ability to emit light of any color by selecting the phosphor used. When cathode ray tubes are used as light sources for large display devices, they have lower performance, reliability, maintenance costs, and
It is clear that this method is advantageous in terms of power consumption and other aspects.

By the way, when a cathode ray tube is used as a light source in such a display device, it has various advantages as mentioned above, but it also has the advantage of increasing light output without increasing the effective diameter of the cathode ray tube itself. If this can be achieved, the above advantages can be more effectively exhibited.

This invention was made in view of the above points,
It is an object of the present invention to provide a cathode ray tube for a light source that can maximize the light output without increasing the effective outer diameter of the cathode ray tube by making the face plate part conical.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A cathode ray tube for a light source according to an embodiment of the present invention will be described below with reference to the drawings.

In FIG. 3, the same reference numerals as in FIG. 1 indicate the same or corresponding parts, and the difference from FIG. 1 is that the face plate portion 3 is configured to have a conical surface. In this embodiment, both the inner and outer surfaces are formed into a substantially truncated conical shape, but they may also be formed into a conical shape.

Further, the object of the present invention can be achieved by forming at least the inner surface into a conical surface.

To explain this point, the present invention attempts to maximize the light output without increasing the outer diameter of the cathode ray tube, as described above. In other words,
When the unfocused electron beam 12 having a size that covers the effective diameter of the fluorescent surface 2 illuminates the fluorescent surface 2, the surface area of the fluorescent surface 2 should be made larger without increasing the effective diameter of the cathode ray tube. Assuming that the electron beam irradiation density per unit area of the fluorescent surface 2 is the same, the larger the surface area of the fluorescent surface 2, the more light output can be obtained as a cathode ray tube.

That is, in this type of cathode ray tube, unlike the direct-view type for general television, there is no need to form the fluorescent surface 2 into a flat surface or a curved surface similar to this, but simply by increasing the surface area of the fluorescent surface 2. By making it as large as possible and irradiating it with as many unfocused electron beams 12 as possible, the maximum optical output can be obtained.

Therefore, if the inner surface of the face plate portion 3 is made into a conical surface and the fluorescent surface 2 is formed thereon as in the embodiment shown in FIG. By increasing the length of the plate portion 3, the surface area of the fluorescent surface 2 can be increased.

That is, by setting the length of the face plate part 3 so that it is larger than the inner surface area of the face plate part 3 in the case of the hemispherical surface shown in FIG.
The surface area of the fluorescent surface 2 can be made larger than in the case of FIG. The length of the face plate portion 3 can be set, for example, as follows.

Now, if the diameter of the cylindrical part 1 is l and the radius is r, then
In the case of the hemispherical surface shown in FIG. 1, the inner surface area of the face plate portion 3 is 2πr ² .

On the other hand, if the face plate portion 3 is made into a conical shape, for example, according to the present invention, and if the generatrix of this conical face plate is S, then its inner surface area is πrS
becomes.

Therefore, in order ^to make the inner surface area larger than in the case of FIG.

As explained above, according to the present invention, it is possible to maximize the light output without increasing the effective outer diameter of the cathode ray tube itself, making the cathode ray tube particularly suitable as a light source for large display devices. can be provided.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway view showing a conventional light source cathode ray tube, FIG. 2 is a layout diagram of a light source cathode ray tube used in constructing a display device, and FIG. 3 is a partial view showing an embodiment of the present invention. It is a cutaway view. In the figure, 1... cylindrical part, 2... fluorescent surface, 3...
Face plate section, 4...electron gun, 12...unfocused electron beam. In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1 A vacuum envelope having a cylindrical part and a face plate part provided at one end of the cylindrical part, a fluorescent surface formed on the inner surface of the face plate part, and a fluorescent surface provided in the other end of the cylindrical part. , in a cathode ray tube for a light source equipped with an electron gun that emits an unfocused electron beam at a predetermined divergence angle toward the fluorescent surface, at least an inner surface of the face plate portion is a conical surface; cathode ray tube.