JPS6357910B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cathode ray tube for a light source, and more particularly to a cathode ray tube for a light source suitable for a large-screen image device constructed outdoors or the like.

We have seen cases where large image display devices are installed on back screens of baseball stadiums, and, for example, moving images praising batters who hit home runs are displayed. This image display device requires a high-brightness light source as an element that becomes a pixel so that it can be seen from a long distance, and for this reason, high-power, high-brightness incandescent light bulbs are often used, and thousands to tens of thousands of light bulbs are installed on a flat surface. It is configured to display an image by arranging them and blinking them using a relay switch or the like. However, such an image display device has the following drawbacks.

That is, in order to make a high-power light bulb blink, it is necessary to turn it on and off with a switch, and this operation requires a considerable amount of power. It is extremely difficult to turn on and off such a large amount of power using electronic circuits.
It costs a lot of money to make the device circuit. Furthermore, because of the time delay in the temperature rise of the filament of the light bulb, it is not possible to display television images by switching at high speed. Furthermore, because incandescent light bulbs require a large amount of power and there is a time delay in changing the temperature of the filament, it is extremely difficult to perform brightness modulation as quickly as in television images. In order to construct a multicolor image such as that used in commercial color television broadcasting, it is found that it is extremely difficult to use incandescent light bulbs for the three primary colors of blue, red, and green, and to modulate their brightness. Furthermore, incandescent light bulbs have a short lifespan, usually around 1,000 to 3,000 hours, which is inferior to the long lifespan of cathode ray tubes, which can last more than 10,000 hours, so maintenance and replacement requires a great deal of effort and expense.

The present invention was made in order to eliminate such drawbacks, and an object of the present invention is to provide a cathode ray tube for a light source that can be advantageously used in place of a conventional incandescent light bulb for constructing an image display device. By using a cathode ray tube, high-speed switching and high-speed brightness modulation are possible with low power consumption using electronic circuits.
Furthermore, it is possible to construct an image display device that has a long life and reduces maintenance costs.

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is an external view showing a schematic structure for explaining the overall structure of an embodiment of the present invention. Referring to FIG. 1, a tube body 1 is composed of an upper case 2 and a lower case 3, both of which are joined by a frit seal 4. As shown in FIG. The upper case 2 includes a window 5 for passing light emitted from a phosphor screen, which will be described later, and is therefore made of glass, but the lower case 3 is made of glass.
It may be constructed of ceramic or metal. It goes without saying that the upper case 2 does not need to be entirely made of glass, and the parts other than the window 5 may be made of ceramic or metal. With this configuration, the cathode 6 and the control electrode 7 can be visually observed through the window 5 of the upper case 2. The cathode 6 is placed approximately in the center of the window 5. Details of the configuration of the cathode 6, control electrode 7, etc. will be described later with reference to FIG. 2. A plurality of terminals 8 for applying an operating voltage to the cathode 6, the control electrode 7, the acceleration electrode 12 (FIGS. 2 and 3), etc. are installed around the periphery of the upper case 2. At the periphery of the lower case 3, there is a fluorescent screen 17.
An anode button 9 for applying a high voltage is embedded in (FIGS. 2 and 3). Details of the above configuration will become clear from the following description with reference to FIG.

FIG. 2 is a schematic structural cross-sectional partial view for explaining the internal structure of the light source cathode ray tube shown in FIG. Second
Referring to the figure, a cathode 6 is placed under the window 5 of the upper case 2. The cathode 6 consists of a heater 10 and an electron emissive material layer 11 coated around the periphery. Although the cathode 6 illustrated here is a directly heated cathode, it may be an indirectly heated cathode. A control electrode 7 made of a mesh-shaped plane electrode is arranged in front of the cathode 6 and at a predetermined distance from the front surface thereof. In front of the control electrode 7 and at a predetermined distance from the front surface thereof, an accelerating electrode 12 made of a mesh-shaped plane electrode is arranged parallel to the control electrode 7 .
Accelerating electrode 12 may be composed of a plurality of electrodes. Control electrode 7 and acceleration electrode 12 are held by support frame 13 . The bottom surface 14 of the lower case 3 is formed into a concave shape having a center of curvature in the light emission direction of the phosphor screen 17. However, it is essentially necessary to form the fluorescent screen 17 in a concave shape, and the lower case 3
It is not necessarily necessary to form a concave shape by itself, and it may be replaced with a plate-like one formed in a concave shape. A metal back 15 is applied to the concave bottom surface 14,
A phosphor layer 16 is applied thereon to form a phosphor screen 17. The fluorescent screen 17 extends substantially parallel to the accelerating electrode 12. The metal back 15 is connected to the anode button 9 and functions both as an electrode for applying a phosphor screen voltage and as a film for reflecting light emitted from the phosphor layer 16.

FIG. 3 is a schematic cross-sectional view of the structure for explaining the operational functions of the cathode ray tube for light source shown in FIG. Referring to FIG. 3, with respect to cathode 6, a negative voltage is applied to control electrode 7, a positive voltage is applied to accelerating electrode 12, and a high voltage higher than the accelerating electrode voltage is applied to fluorescent screen 17.
These voltages are equal to the electron current 1 emitted from the cathode 6.
8 (shown as a dotted line in FIG. 3) is adjusted to form a flat beam that illuminates the entire phosphor screen 17. Then, light emission 19 from the entire fluorescent screen 17
(indicated by an arrow in FIG. 3) passes through the mesh of the accelerating electrode 12 and the control electrode 7, and passes through the window 5 of the upper case 2.
is emitted from the tube body 1. Since the fluorescent screen 17 is formed into a concave shape as described above, the emitted light 19 is converged and does not diverge. It goes without saying that it is particularly desirable to select the center of curvature of a concave surface as the viewing point.

A plurality of such light source cathode ray tubes are arranged in a plane to constitute an image display device. Image projection is achieved by using individual light source cathode ray tubes as pixel components and sequentially modulating the brightness. Note that when viewing individual light source cathode ray tubes from a close distance, the cathode 6 may be visible, but when constructed as an image display device, the cathode 6 will be viewed from a long distance, so the cathode 6 may not be visible. Instead, the entire light source cathode ray tube can be regarded as one bright spot, and it does not interfere with the field of view.

The light source cathode ray tube thus obtained has the following characteristics. That is, unlike an incandescent light bulb, brightness can be modulated by changing the potential of the control electrode 7 in the same way as a normal cathode ray tube.
Pixels can be switched at high speed using electronic circuits, and if an image display device is built using this, it will be possible to display television broadcasts on a huge screen.
Further, the power required for switching is extremely small. In addition, by regularly arranging three color light source cathode ray tubes coated with phosphors of the three primary colors of red, green, and blue, and using one set of three colors as one pixel, color synthesis can be performed by modulating the brightness of each color. , it is possible to project color images. Further, the cathode 6 has a band-like shape,
Therefore, it is possible to have a large electron emission area, and since it is controlled and accelerated by a mesh-like electrode, a large current can be extracted, and the current density that serves as the cathode load can be small, making it easy to have a long life. It is possible to reduce maintenance costs such as replacement. Furthermore, since the fluorescent screen 17 is formed in a concave shape, the light emitted 19 does not diverge and is focused in the direction of the viewer, making it possible to obtain an efficient and bright screen. Furthermore, since the outer shape of the phosphor screen 17 can be arbitrarily and efficiently made to have a large area, the efficiency of the light emitting area can be made much larger than that of an incandescent lamp, and a bright image can therefore be obtained. In addition, since the luminous area efficiency is excellent, the screen is fine and smooth, and does not give a rough feeling like a screen made with an incandescent light bulb. In addition, since the bottom surface 14 of the lower case 3 can be made smooth, the metal back 15 can be made a mirror surface to improve the reflection performance, and thereby the light emission 19 of the phosphor layer 16 can be made smooth.
is efficiently reflected by the metal back 15, resulting in a bright light source cathode ray tube.
In addition, the mesh of the control electrode 7 or the accelerating electrode 12 can transmit a large current of emitted electrons from the cathode 6, so a large current can be passed through the phosphor screen, resulting in high brightness. It has the effect of preventing the phosphor from deteriorating due to light rays.
In addition, since the phosphor layer 16 is directly irradiated with electrons by a flat beam, there is no energy loss of the electron beam due to the metal back, unlike the threshold loss caused by the metal back of ordinary cathode ray tubes, and therefore the threshold voltage of the phosphor screen is reduced. It can be lowered by the value of the value. This value is usually a high voltage of about 5KV,
This effect is extremely large. Furthermore, since the phosphor screen 17 is formed on the back of the light source cathode ray tube, it is easy to cool it and is suitable for a large screen image display device built outdoors.

As described above, the cathode ray tube for a light source according to the present invention can be said to have many advantages, and is particularly excellent in its ability to be used outdoors under harsh natural conditions such as sunlight and temperature.

It goes without saying that the shapes of the tube body, electrode mesh, etc. are not limited to those shown in the drawings.

[Brief explanation of the drawing]

FIG. 1 is an external view showing a schematic structure for explaining the overall structure of an embodiment of the present invention. Second
This figure is a partial cross-sectional view of a schematic structure for explaining the internal structure of the cathode ray tube for light source shown in FIG. FIG. 3 is a schematic cross-sectional view of the structure for explaining the operational functions of the cathode ray tube for light source shown in FIG. In the figure, 1 is a tube body, 6 is a cathode, 7 is a control electrode, 12 is an acceleration electrode, 15 is a metal bag, and 16
is a phosphor layer, and 17 is a phosphor screen. In the drawings, the same or corresponding parts are given the same reference numerals.

Claims (1)

[Claims] 1. (a) A tube having a phosphor screen forming surface and a window portion located opposite to the phosphor screen forming surface and allowing light emitted from the phosphor screen to pass through; (b) the phosphor screen forming surface within this tube. (c) a phosphor screen formed in a concave shape with a center of curvature in the direction of the window of the tube; , a mesh-shaped accelerating electrode that is disposed opposite to the phosphor layer of the phosphor screen, and whose external shape when viewed from the window of the tube is almost the same as the external shape when viewed from the window of the phosphor screen; (d) disposed in the tubular body, located closer to the window of the tubular body than the accelerating electrode, and facing the accelerating electrode; (e) a mesh-shaped control electrode having an external shape that is almost the same as seen from the window of the tube; The cathode is provided with a strip-shaped cathode whose external shape when viewed from the window of the body is smaller than the external shape when viewed from the window of the tube body of the control electrode, and which emits an electron flow in the direction of the control electrode, The voltages applied to the control electrode, accelerating electrode, and metal back of the phosphor screen are set so that the electron flow emitted from the cathode forms a flat beam that irradiates the entire surface of the phosphor screen, and the flat beam from the cathode illuminates the entire surface of the phosphor screen. A cathode ray tube for a light source, characterized in that light emitted from the tube passes through the acceleration electrode and the control electrode and is radiated out of the tube from a window portion of the tube.