JPS58223253A - Cathode-ray tube for light source - Google Patents

Abstract

PURPOSE:To enhance the luminance of a cathode-ray tube for a light source by insulating in a vacuum encircling case both an electron gun and a cylindrical metallic structure the inner surface of which is coated with a fluorescent film, and irradiating a non-focusing electron beam discharged from the electron gun upon the fluorescent film. CONSTITUTION:An electron gun 4 which is constituted of a cathode 7, a grid 8 and an accelerating electrode 11 and produces flood beams, is installed inside a vacuum encircling case 1. At the same time, a cylindrical metallic structure 12 the inner surface of which is coated with a fluorescent film 20 and in which the diameter of its opening located distant from the electron gun 4 is larger than the diameter of its opening located nearer the electron gun 4, is installed in front of the electron gun 4, thereby constituting a cathode-ray tube which emits monochromatic light of red, green, blue or the like used as a picture element of a giant color display device. Owing to such constitution, the surface area of the fluorescent screen working as an emissional part, can be increased. Consequently, the luminance of the cathode-ray tube can be greatly enhanced by taking out much light.

Description

[Detailed description of the invention]

The present invention relates to a light source cathode ray tube that constitutes a pixel of a huge color display device used mainly outdoors. Conventionally, huge display devices used for example, electric display boards at baseball stadiums, advertising images and messages on the rooftops or walls of buildings, and information displays on expressways, etc., are arranged with a large number of light bulbs and selected. Since the image was created by blinking, there were many problems. To give some examples, for example, in the case of a light bulb, the light is obtained from the red heat of the filament, so
Its luminescence is mainly orange or white-orange. For this reason, it has been quite difficult to produce colored light, such as blue or green, on a platter from these 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 off the applied current to the filament or change the applied current by a certain amount. The frequency response of these light bulbs is extremely low, less than 1QBia, and there is a problem that the emitted light color itself changes to 0 depending on the applied current, making it difficult to use for halftone display or color display that synthesizes arbitrary colored light. It followed me. Furthermore, in such a huge display device, there are many cases in which several thousand to tens of thousands or more of 20 to 40 W bulbs are lined up, and their dissipation %R[, power, heat generation, etc. It also had many problems. Therefore, the inventor proposed using a cathode ray tube as a light source for the above-described display device. In other words, a large number of small cathode ray tubes that emit monochromatic fluorescent light such as red, green, and blue are lined up to display a desired image.

[Accordingly, the energy conversion efficiency of converting electrical energy into light energy is not only greatly improved compared to the light bulb, but also a light source that can emit light of any color by selecting the phosphor used. There were many advantages such as the ability to obtain It is clear that when cathode ray tubes are used as the light source for giant display devices, they can be constructed with advantages over conventional light bulb type devices in terms of performance, reliability, maintenance costs, power consumption, etc. It is. FIG. 1 is a diagram showing an example of a light source cathode ray tube used as a light source for such a huge display, and (1) is, for example, a cylindrical vacuum envelope for maintaining a vacuum inside the tube. This vacuum envelope (1) has a fluorescent surface (
2), and an electron gun (4) for irradiating the entire surface of the fluorescent surface (2) with an unfocused electron beam (10), and an electron gun (4) at the other end. ) has a terminal for applying the required 'KIEk to each part of the vacuum envelope (1), and a stem part (5) for closing the vacuum envelope (1). (ill
). (7) and (8) are a heater, a cathode, and a grid, respectively, constituting the electron gun (4). To explain the operation of this cathode ray tube, first, a negative bow pressure is applied to the grid (8) with respect to the negative (7), and a predetermined current is applied to the heater (6) to heat one cathode (7). When the field of the grid (8) is brought close to the potential of the cathode (7), the electron beam (10) is emitted from the cathode (7) onto the fluorescent surface (
2) is fired towards. This electron beam uO) is generated by the diameter of the hole (9) provided in the center of the grid (8), the distance between the grid (8) and the cathode (7), and li! The polar voltage becomes an unfocused beam with a predetermined divergence angle θ depending on the voltage conditions.
) All phosphors emit light in a color that corresponds to the phosphor. However, in such a cathode ray tube, the applied current is limited due to the temperature rise of the fluorescent surface due to the irradiation energy of the electron beam, which is one of the factors that hinders the increase in brightness. SUMMARY OF THE INVENTION An object of the present invention is to provide a cathode ray tube for a light source that can eliminate such drawbacks, greatly improve brightness, and construct a bright display. FIG. 2 shows an embodiment of the present invention. Vacuum envelope (1)
There is a cathode (γ), a grid (8), and an accelerating electrode inside the
An electron gun that generates a flood beam composed of
4) '! A cylindrical metal structure [12] with a fluorescent film formed on the inner surface is provided in front of the electron gun (4), and an electron beam (]0 emitted from the cathode (7) is provided in front of the electron gun (4). ) is efficiently irradiated onto a fluorescent film to generate light. Here, the fluorescent surface formed by the fluorescent film (a) is the first
Compared to the fluorescent surface (2) in the figure, the surface area can be much larger. The fact that the surface area of this light-emitting part is large means that a large amount of light can be extracted, and the brightness can be greatly improved. Additionally, since the metal structure that holds the fluorescent surface can be made of a metal with good thermal conductivity, it is less affected by temperature quenching, which also helps to significantly improve brightness. . In addition, as shown in Figure 2, this metal structure trunk can be coated with a fluorescent film by making the aperture diameter on the side opposite to the electron gun (4) larger than the aperture diameter on the electron gun (4) side. It is possible to easily lead out the luminous energy of the tl-tube to the outside of the tube. In addition, as shown in Fig. 5, the inner surface of the accelerating electrode (11) disposed between the metal structure (b) and the cathode (7) is mirror-treated to make it easier to reflect light. If we form a country... For example, if we trace the light emission at point P, light a will directly go outside the tube, part of it will be reflected by the phosphor on the opposite side, and part of it will be lost. The light emitted toward the cathode (7) such as c, kai, . . .
0 each. →0. →03→04→05→Q6 →07
r (11 → 6 goose → dl + 1111 → J * f
It is guided out of the tube while repeating reflections as shown in 1. Such multiple reflection allows light to be extracted more effectively for use as a light source. Furthermore, on the inner surface of the vacuum envelope (1) opposite to the electron gun (4) in FIG.
By providing this transparent conductive film (10) with a discharge potential higher than that of the fluorescent film (10), the fluorescent film (10) can be efficiently irradiated with the electron beam (10). It becomes possible to obtain higher brightness. As described above, according to the present invention, the surface M of the fluorescent surface
This has the effect of providing a cathode ray tube for use as a vertical light source, which can be used as a highly efficient light source and further improve the performance of display images.

[Brief explanation of drawings]

FIG. 3 is a diagram showing the main parts. (1)...Vacuum envelope, (4)...Electron gun, aO)
...electron beam, (b)...metal structure, (company)...
- Fluorescent film. Note that the same reference numerals in the figures indicate the same or corresponding parts. Agent Makoto Kuzuno (1 other person) 5-28C.

Claims (1)

[Scope of Claims] A cathode ray tube for a light source, comprising a cylindrical metal structure on which a film is formed, and the fluorescent film is irradiated with an unfocused electron beam generated from the electron gun. (2) The above-mentioned cathode ray tube. A cathode ray tube for a light source according to claim 1, characterized in that the aperture diameter on the side opposite to the electron gun of the metal structure is larger than the aperture diameter on the electron gun side. (3) The Joki Seiko gun has a cathode and The cathode ray for a light source according to claim 1, further comprising an accelerating electrode disposed between the cathode and the metal structure, the accelerating electrode having an inner surface mirror-finished. (4) A transparent groove 1JL film is provided on the inner surface of the vacuum envelope on the side opposite to the electron gun, and a lower potential than the fluorescent film is applied to the transparent conductive film. The cathode ray tube for light source according to item 1.