JPS6353667B2 - - Google Patents

Description

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

Conventionally, giant display devices, such as electronic display boards at baseball stadiums or devices that display advertising images on the rooftops or walls of buildings, have been made by arranging a large number of colored light bulbs and selectively blinking them. I was creating an image using this technique, and I encountered a number of problems.

To give a few examples, for example, in the case of a light bulb, the light is obtained by the red heat of the filament, so the color is mainly red or white light. For this reason, when extracting green or blue light from the above-mentioned light bulb, green or blue colored glass is used, and it is quite difficult to extract a large amount of these colored lights. 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 of the filament on and off or to vary the applied current, and the frequency response is Ten
It was extremely low, below Hz, and in addition, there was a problem that the applied current and light emission were not linear, the color development itself changed depending on the applied current, and it was difficult to display halftones. Furthermore, the light bulbs used in these giant display devices are generally 10W or more, so the power consumption and heat generated by the light bulbs in giant display devices, where tens of thousands or more can be lined up, are large. There were some problems.

Therefore, the inventors of the present invention came up with the idea of 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 in a single color such as red, green, or blue are lined up to display a desired image.According to this, the efficiency of converting electrical energy into light energy is higher than that of a light bulb. Ten
In terms of m/W, cathode ray tubes are said to be approximately 100 m/W, which is about an order of magnitude better than light bulbs. In addition, when using a cathode ray tube, the phosphors available in various colors such as red, green, and blue make it possible not only to create a light source with any color, but also with frequency response. Since you can easily obtain a good quality one, you can display videos without any problems.
Furthermore, since the luminance can be changed faithfully in response to the input electrical signal, it is ideal for reproducing halftones. In addition, in terms of lifespan, cathode ray tubes have a considerable advantage over bulb-type devices in which the filament current is varied, since the heater wears out much less.

As described above, when a cathode ray tube is used as a light source, especially in the case of a large display device, it is extremely superior in various respects such as performance, reliability, maintenance costs, and power consumption.

By the way, there are various advantages when using a cathode ray tube as a light source for a display device, but it would also be possible to maximize the light output without increasing the effective diameter of the cathode ray tube itself. The above advantages can be effectively demonstrated.

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 display device that can maximize light output without increasing the effective diameter (diameter) itself.

Embodiments of the present invention will be described below with reference to the drawings. The figure is a side sectional view showing one embodiment of a cathode ray tube for a display device according to the present invention, and in the figure, numeral 1 denotes, for example, a cylindrical vacuum envelope for maintaining a vacuum inside the tube. One end of the vacuum envelope 1 has a face plate 3 having a fluorescent screen 2 adhered to its inner surface. In this case, the face plate 3 is formed into a spherical or parabolic surface shape with a radius of curvature smaller than the maximum outer diameter of the face plate 3. The other end of the vacuum envelope 1 holds an electron gun 4 that generates a flat electron beam (described later) and a terminal for applying a required voltage to each part of the electron gun 4, and also closes the vacuum envelope 1. It has a stem portion 5. Reference numerals 6, 7 and 8 are a heater, a cathode and a grid, respectively, constituting the electron gun 4. In addition, 9 is a hole provided in the center of grid 8, and 10
is a flat electron beam emitted from the electron gun 4 (cathode 7).

Next, the operation of the above-mentioned invention device will be explained.
First, a negative voltage is applied to the grid 8 with respect to the cathode 7, and a predetermined current is applied to the heater 6.
When the grid 8 voltage is brought close to the cathode 7 potential by heating, an electron beam 10 is emitted from the cathode 7. This electron beam 10 becomes an unfocused beam with a predetermined spread θ depending on various conditions such as 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 the anode voltage. 2, and the color develops in accordance with the phosphor.

In this case, the device of the present invention attempts to maximize the light output without increasing the diameter of the cathode ray tube. In other words, when the electron beam 10 having a size that covers the effective diameter of the phosphor screen 2 illuminates the phosphor screen 2, an attempt is made to maximize the surface area of the phosphor screen 2 without increasing the effective diameter of the cathode ray tube. Assuming that the irradiation density of the electron beam 10 per unit area of the phosphor screen 2 is the same, the larger the surface area of the phosphor screen 2, the greater the light output can be obtained as a cathode ray tube.

That is, unlike direct-view type cathode ray tubes for general televisions, there is no need for the phosphor screen 2 to be formed into a flat surface or a curved surface similar to this, and the surface area of the phosphor screen 2 is simply made as large as possible. By irradiating this with as many electron beams 10 as possible, the maximum light output is obtained.For this purpose, the face plate 3 having the phosphor screen 2 is formed with a radius of curvature smaller than the maximum outer diameter of the face surface. It is formed into a surface shape such as a spherical shape or a parabolic shape.

Here, we have described a huge display device in which a large number of cathode ray tubes are lined up, each having a face plate formed into a planar shape with a radius of curvature smaller than the maximum outer diameter of the face surface, but the cathode ray tube of the present invention can be Needless to say, it is suitable even when used alone in lighting, traffic lights, etc.

Therefore, according to the present invention, it is possible to obtain the maximum light output without increasing the effective diameter (diameter) itself, and it is possible to provide a cathode ray tube that is particularly suitable as a light source for a huge display device.

[Brief explanation of the drawing]

The figure is a side sectional view showing an embodiment of a cathode ray tube for a display device according to the present invention. 2... Fluorescent screen, 3... Face plate, 4...
...Electron gun. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A cylindrical vacuum envelope, a face plate provided at one end of the vacuum envelope and having a monochromatic luminescent phosphor screen adhered to the inner surface, and disposed within the other end of the vacuum envelope, an electron gun that emits an unfocused electron beam having a size that covers the effective diameter of the phosphor screen; 1. A cathode ray tube for a display device comprising a cathode ray tube constituting a light source of the display device, wherein the face plate is formed into a planar shape with a radius of curvature smaller than the maximum outer diameter of the face.