JPH0660833A - Color cathode-ray tube - Google Patents

Abstract

PURPOSE:To sharply eliminate difficulty to apply a fluorescent film narrow in stripe width, by adopting a face plate having constitution, in which a broad- width fluorescent film is applied to the inner surface of the face plate of an index color CRT and a stripe-like optical filter, composed of three colors and black, is stuck to the outer surface of the face plate. CONSTITUTION:A narrow-width three-color fluorescent screen stripe, applied to a color index fluorescent film, is substituted with a broad-width fluorescent lamp stripe luminous in white. In this CRT, when a stripe-like optical filter of red, green, and blue and a black filter, transmitting no light, are stuck between various-color filters corresponding to the area of the fluorescent screen decided by the modulation of respective colors of the color modulation signal of an electron beam from an electron gun, to the outside a face plate to which a fluorescent screen is applied; only each color light, synchronized with the three-color video signal of red, green, and blue is transmitted through the filters to appear on an observance side. Consequently a color picture image can be displayed by using a former electron circuit.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an index type color cathode ray tube.

[0002]

2. Description of the Related Art An ordinary color cathode ray tube (hereinafter abbreviated as CRT) uses a combination of a three-electron gun and a shadow mask to emit fluorescent films respectively coated in three colors,
I got a sharp color image. The biggest drawback of the shadow mask system is that about 70% of the electron beam from the electron gun can be stopped by the shadow mask. Not only the mechanical deformation by heating the shadow mask metal by the electron beam, but also the reduction of the power consumed by the CRT,
Various new CRTs capable of displaying a color image by a method different from the conventional CRT have been considered. From these considerations, the index color CRT has been attracting attention because it can project color images with a single electron gun without using a shadow mask. Index color C
The RT has a built-in single-electron gun and a fluorescent film in which an index fluorescent film is added to the conventional fluorescent film.
Is different from. In order to display a color image on a fluorescent film with an index color CRT, the entire surface of the fluorescent film is scanned at high speed with an electron beam from one electron gun, and the time during which the electron beam is applied to each color fluorescent film stripe During that, the electron beam is modulated with a video color image signal. A color image is obtained by sequentially performing color modulation of the electron beam. Due to the high speed of the scanning electron beam and the very narrow width of the fluorescent film stripe, the time for which the scanning electron beam irradiates one fluorescent film stripe is very short. Therefore, in order to accurately color-modulate the electron beam on the phosphor screen, it is necessary to accurately align the electron beam in the phosphor film. For the purpose of electron beam alignment, index fluorescent film stripes are provided in the fluorescent film at appropriate intervals. When the scanning electron beam illuminates the index phosphor, the index phosphor film emits light. The light emission of this index fluorescent film is detected, the scanning position of the electron beam on the fluorescent film surface is specified, the modulation time of the electron beam is corrected at any time, and each color fluorescent film stripe forming the three-color fluorescent film surface is converted into an electron beam. Emits light without error and displays a color image.

The index color CRT is a shadow
Since no mask is used, there is an advantage that the utilization efficiency of the electron beam is high. From this, the index color CRT is
In recent years, attention has been given to obtaining a bright fluorescent film. By the way, the three-color fluorescent film of the currently manufactured index color CRT has the same structure as the fluorescent film for a color CRT using an ordinary shadow mask. Since the three-color fluorescent film is manufactured by sequentially coating the three-color fluorescent substances, the manufacturing process becomes complicated and the manufacturing becomes difficult. In particular, the miniaturized index color CRT phosphor film has a stripe width extremely narrow, which makes it difficult to form the phosphor film.

In recent years, there has been an increasing tendency to use index color CRTs for display devices of portable equipment. Portable devices are required to be downsized so that they are convenient to carry. There are several difficulties encountered in miniaturizing index color CRTs. The first is to minimize the width of the fluorescent film stripe. Miniaturized index color CRT
The fluorescent film stripe width is, for example, 1.3 inch CRT
In order to make, the width of the stripe should be less than one tenth of the stripe width of the 13-inch color CRT. Since the 13-inch color CRT has a stripe width of 0.14 mm, the 1.3-inch CRT requires a tenth of the stripe width, that is, 14 μm or less. In order to form a fluorescent film having such a narrow stripe width, a printing method using photosensitivity is generally used. Regardless of which coating method is used, in order to form a fluorescent film having a narrow stripe width, the particle diameter of the phosphor used must be considerably smaller than the stripe width. Ideally, good results are obtained when the width is one fifth of the stripe width, that is, 3 μm or less. As described above, even if a phosphor having a small particle size is used, it is difficult to form a small-sized color CRT phosphor stripe having few defects with a high yield.

[0005]

The problem to be solved is to provide a new face plate for an index color CRT which solves the difficulty of applying a phosphor film having a narrow stripe width to the face plate of a CRT.

[0006]

SUMMARY OF THE INVENTION The present invention replaces all of the narrow three-color phosphor screen stripes applied to a color index phosphor screen with a wide white phosphor screen. When this fluorescent film is operated under the same scanning conditions as for a normal index color CRT, white light emission is obtained. On the outside of the face plate coated with a fluorescent film by this CRT, stripe-shaped red, green, corresponding to the area of the fluorescent film determined by the modulation of each color of the color modulation signal of the electron beam from the electron gun, If a blue optical filter and a black filter that does not transmit light are pasted between the filters of each color, only the light of each color synchronized with the three-color video signals of red, green, and blue will pass through the filter and will be transmitted to the observation side. Come out. Therefore, the electronic circuit that scans the electron beam is
By replacing the face plate with the fluorescent film that emits light in three colors as it is, with a face plate that is a combination of a fluorescent film that emits white light and a color filter,
Obtain an index color CRT that can project a color image on the face plate of the CRT.

The fluorescent film that emits white light must contain light in the entire visible region under the irradiation of an electron beam. Preferably,
It is desired that the light emission of the phosphor constituting the fluorescent film is linear light emission, and the intensity of the linear light emission line is color balanced. Europium (Eu) for such phosphors
And yttrium sulfate phosphors activated with terbium (Tb). This phosphor has a terbium concentration of 3 × 1.
0 ⁴ in 5 × 10- ³ mol, concentration of europium 3 ×
When in the range of 10 ⁴ 3 × 10 ³ mol, showing the preferred white. As shown in FIG. 1, the phosphor activated with the optimum europium and terbium concentrations has a linear emission spectrum in the entire visible light range. This phosphor is evenly applied to the inner surface of the face plate of the index CRT between the applied index phosphor films, as illustrated in FIG. This fluorescent film emits white light under the irradiation of an electron beam.

Stripe-shaped red, green, blue and black color filters are attached to the outer surface of the face plate of the index CRT at suitable intervals according to a predetermined order. FIG. 2 illustrates an example of an array of color filters in a sectional view. When irradiated with an electron beam scanned under normal color TV conditions, the face plate to which a color filter is attached selectively transmits light from the fluorescent film that emits white light through the filter. The image above emits black and white light and cannot display a color image. In order to display a color image on the face plate, the scanning electron beam irradiating the fluorescent film must be modulated under the scanning conditions of the index color CRT. An example of the modulated electron beam is illustrated in the upper part of FIG. The electron beam is scanning from left to right. When the electron beam is modulated as shown, a color image is obtained from the face plate.

Color to be attached to the face plate
As the filter, a film-like filter in which a color pigment is dispersed in an organic substance may be attached. Alternatively, a photosensitive solution in which a color pigment is dispersed may be applied onto a face plate substrate and then applied to a filter of a prescribed size by a photolithography technique. Further, the glass substrate itself may be configured as each component of the color filter by diffusing the element ions serving as a coloring material inside the glass substrate. Whichever method you use, you can
The size of the color filters and the modulation of the scanning electron beam must be synchronized for projection onto the plate.

The white light emitting phosphor film may be applied uniformly on the entire surface of the CRT face plate, and an index phosphor film stripe may be applied on the CRT face plate in a specified width at a specified position. In addition, a stripe of a carbon film that becomes a light absorber or a metal thin film (hereinafter referred to as a carbon film) that is a light shield is applied on the face plate in advance to the width of the index fluorescent film, and the index fluorescent film is formed. The film may be applied on a carbon film or the like. In these cases, the fluorescent film emits light even at an anode voltage of 2 kV or less. Therefore, for a display device with low power consumption, it is preferable to form the fluorescent film by the above method. In order to obtain a high-luminance light emitting surface, it is preferable to increase the energy of the electron beam, but in that case, the light emission of the fluorescent film is deteriorated by the remaining trace amount of ionized gas. To prevent deterioration,
An aluminum thin film, which is commonly called an aluminum bag, may be arranged on the white light emitting fluorescent film on the electron gun side of the fluorescent film. In this case, the emission of the index fluorescent film stripe cannot be detected unless the index fluorescent film stripe is applied on the aluminum back.

The face plate to which the fluorescent film is applied is
You may use the transparent glass plate normally used for CRT. When a glass plate made by bundling light and fibers is used for the glass plate, blurring of the image due to internal scattering of the glass plate is eliminated, and the effect of using the optical filter is emphasized. The result is a clear color image on the face plate.

[0012]

As described above, a wide fluorescent film is applied to the inner surface of the face plate of the index color CRT, and a striped optical filter consisting of three colors and black is attached to the outer surface of the face plate. By adopting a face plate having a different structure, the difficulty of applying a fluorescent film having a narrow stripe width is significantly reduced. Furthermore, by using an optical fiber substrate for the face plate, an index color CRT that projects an image with good resolution on the face plate can be obtained.

[Brief description of drawings]

Figure 1 shows the emission spectrum of the white phosphor. FIG. 2 shows a white light emitting fluorescent film applied between index fluorescent films, and a blue film attached to the opposite side of the substrate corresponding to the white light emitting fluorescent film,
Sectional drawing which shows arrangement | positioning of green, red, and a black filter, and the schematic diagram which shows the time modulation of the electron beam with which a white fluorescent film is irradiated.

Claims (3)

[Claims] 1. A uniformly coated white light emitting phosphor film having a striped index phosphor film applied at a predetermined interval on an inner surface of a glass substrate which is a face plate of a cathode ray tube. Alternatively, a white light emitting fluorescent film coated with wide stripes coated at a predetermined interval and a visible light absorber such as a carbon film between the striped fluorescent films or a light shielding material such as a metal film. The white fluorescent film, which is isolated by a barrier consisting of, and is formed by applying an index fluorescent film on the above-mentioned light absorbent film, or
A single electron gun index color cathode ray tube with a built-in white light emitting fluorescent film in which a metal back is attached to the white fluorescent film and an index fluorescent film is coated on the metal back, and the outer surface of the face plate of the cathode ray tube. In addition, an electron beam for adhering the white fluorescent film corresponding to the color of the color filter on the outside of the face plate by attaching a color filter consisting of blue, green, red and black stripes to the above white light emitting fluorescent film. An index color cathode ray tube characterized by displaying a color image on a cathode ray tube surface by sequentially modulating a beam according to a color signal. 2. The index color cathode ray tube according to claim 1, wherein the face plate to which the fluorescent film is applied is made of an optical fiber. 3. The white light emitting phosphor film is terbium (Tb).
Yttrium sulphate phosphor (Y ₂ O ₂ S: T), characterized in that it contains two compounds, co-activator and europium (Eu)
The index color cathode ray tube according to claim 1, characterized in that it is composed of b: Eu).