JPH05205659A - Image receiving tube - Google Patents

Abstract

PURPOSE:To manufacture an image receiving tube at a comparactively low cost which is equipped with as well the function to prevent electrostatic charge as the function to reduce photo-reflection due to multifold interfering action. CONSTITUTION:A first composite layer 2 is provided on the outer surface of a glass base board 1 constituting a face panel while a second composite layer 3 is formed over the inner surface of the glass board 1. The two composite layers 2, 3 are furnished with the first photo-transmissive films 4, 6 having a higher refractive index than the glass board 1 and the second photo- transmissive films 5, 7 provided thereover and having a lower refractive index than the glass board 1. The first photo-transmissive film 4 of the first composite layer 2 has electroconductiveness. This permits yielding an image receiving tube exerting good photo-reflex reducing effect with good producibility. Also the effect of preventing electrostatic charge can be obtained, and if the case is a color image receiving tube such can be equipped with an improved white balance amperage ratio.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a picture tube having both antistatic and light reflection reducing functions.

[0002]

2. Description of the Related Art When static electricity is accumulated on the outer surface of a face panel of a picture tube, there is a risk of electric shock and fine dust tends to adhere. Further, when so-called extraneous light from an indoor lighting lamp or the like is specularly reflected on the outer surface of the face panel, the lighting lamp is reflected and the image becomes difficult to see. Therefore, it is generally practiced to chemically or mechanically process the outer surface of the face panel or to coat it with silica to obtain a roughened outer surface, which is used as a measure for preventing specular reflection. Further, an antireflection measure using a multiple interference film is also known. Furthermore, a conductive thin film made of tin oxide doped with antimony, indium oxide doped with tin, or the like is provided on the outer surface of the face panel as a measure for preventing static electricity.

[0003]

However, if the above-mentioned light reflection reducing measures are taken, a large number of fine irregularities formed on the outer surface of the face panel diffusely reflect the external light, but are generated in the phosphor film. Since it also diffuses the reflected image light,
The resolution is reduced and the glossiness is lost. Moreover, since vacuum deposition is required to obtain a conventional multiple interference film, the productivity is low and the cost is high. Further, since the conductive thin film made of the above-mentioned material has a higher light refractive index than the face panel, the light reflection on the outer surface of the panel is further increased, and the illumination lamp or the like is more easily displayed.

[0004]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and includes a first composite layer provided on the outer surface of a glass substrate forming a face panel, and the glass substrate. A second composite layer provided on the inner surface of the first transparent film having a higher optical refractive index than the glass substrate, and a second composite layer provided on the first transparent film. And a second light-transmitting film having a light-refractive index lower than that of the glass substrate, and at least the first light-transmitting film of the first composite layer has conductivity.

[0005]

According to this structure, the optical multiple interference effect is obtained by the glass substrate of the face panel and the first and second composite layers provided on the front and back surfaces of the face panel, so that productivity can be improved without the need for vacuum deposition. A good and good light reflection reducing effect can be obtained. Further, since the first layer of the first composite layer has conductivity, it is possible to obtain the antistatic effect together.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the embodiments shown in the drawings.

A glass substrate 1 shown in FIG. 1 is a so-called front plate portion of a commercially available super dark type face panel which is glass-molded for a 14-inch type color picture tube, and has a light transmittance of 46.5% and a plate thickness. About 10 mm, the optical refractive index is 1.
54. The first and second composite layers 2 and 3 are provided on both front and back surfaces of the glass substrate 1, respectively.
The composite layer 2 is composed of a first transparent film 4 and a second transparent film 5 laminated on the outer surface of the film 4. The second composite layer 3 is composed of the first transparent film 6 and the second transparent film 7 laminated on the outer surface of the film 6.

The thickness of each of the first light-transmitting films 4 and 6 of both composite layers 2 and 3 is 60 nm to 100 nm, and the light refractive index thereof is larger than the light refractive index (1.54) of the glass substrate 1. .64-1.
68, the resistance value is 90,000 MΩ or less. The thickness of each of the second translucent films 5 and 7 of both composite layers 2 and 3 is 68 nm or less.
At 115 nm, its optical refractive index is 1.44 to 1.48, which is smaller than that of the glass substrate 1, and such a film is formed by the following procedure.

The face panel, which has been subjected to the washing and drying treatments, is rotated about 40 rpm at a rotation speed of about 100 rpm.
On the inner surface of the glass substrate 1 kept at a temperature of ° C, the first light-transmitting film 6 containing silica as a main component is uniformly applied and formed.
The coating material used in this film formation was obtained by adding antimony-doped tin oxide, titanium oxide, and silica to an alcohol-based volatile solvent, and the solid content concentration of this solution was about 1.1%. ..

The solution is evenly sprayed through a nozzle for 120 seconds onto the glass substrate 1 of the face panel which is rotating. The coating film thus obtained is heated and dried until the glass substrate 1 reaches a temperature of about 50 ° C.

After lowering the temperature of the glass substrate 1 to about 40 ° C., a second light transmissive film 7 is formed on the first light transmissive film 6 by coating. The spin coating conditions at this stage may be the same as the coating conditions for the first translucent film, and a silica solution is used as the coating material. This solution was obtained by adding silica to an alcoholic volatile solvent, and the solid content concentration of this solution was about 0.75%.

On the outer surface of the glass substrate 1, the first light-transmitting film 4 and the second light-transmitting film 5 are sequentially formed by coating in the same manner as described above. These coatings are applied to the face panel at about 450 ° C.
It is heated to increase its mechanical strength.
Thus, since the first and second composite layers 2 and 3 having a two-layer structure are laminated on both front and back surfaces of the glass substrate 1, a color picture tube is manufactured in the usual manner by using the composite face panel.

The light reflection on the outer surface of the face panel of the obtained cathode ray tube has a spectrum as shown by the curve a in FIG. 2, which is much larger than that of the conventional light reflection shown by the curve b in FIG. It turns out to be very low.

Generally, when considering the light reflection in a picture tube, it is necessary to consider it as the sum of the light reflection on the outer surface and the light reflection on the inner surface of the face panel. When the light reflectance on the outer surface of the face panel is reduced, the light reflection from the inner surface of the face panel becomes noticeable. Therefore, in the present invention, as described above, the second composite layer is provided to reduce the light reflectance on the inner surface side of the face panel.

Incidentally, the light reflection on the outer surface of the picture tube face panel is determined by the light refractive index of the glass substrate 1, and the light reflectance R on the outer surface when a super dark type face panel having a light refractive index of 1.54 is used. _o is 4.5%.
Further, the total light reflectance on both the front and back surfaces is R _s × when the light reflectance of the fluorescent surface is R _s and the light transmittance of the panel glass is T _g.
Since it is _{calculated by} the square of (1-R _o ) × T _g square, in this example, it is 11.8%, which is 4.5% of the external reflectance.
The light reflectance on the inner surface is 7.3% after subtracting. Total light reflectance of the face panel molded using each glass material of Taint type with 57% light transmittance, Gray type with 73.5% light transmittance, and Clear type with 85.5% light transmittance. Are 17.8%, 29.6%, and 40%, respectively.

In the gray type and the clear type, in which the reflection on the inner surface is remarkably larger than the reflection on the outer surface, there is less adverse effect that an illumination lamp is reflected due to the outer surface reflection, and the contrast is improved by reducing the outer surface reflection. Less effective. Therefore, the present invention can be applied particularly to a picture tube using a super dark type and a taint type face panel to obtain a remarkable effect.

A decrease in light reflectance corresponds to an increase in light transmittance. When the bottom wavelength of the external reflection spectrum indicated by the curve a in FIG. 2 is matched with the peak value of the phosphor emission spectrum, the substantial emission brightness of the phosphor is relatively increased as compared with the phosphors of other colors. It is possible to improve the 3-current ratio when obtaining white balance in the picture tube. That is, red to obtain white balance in a color picture tube,
The current ratio R: G: B of green and blue is, for example, 38.7: 3.
If it was 2.0: 29.3, change this to 37.7: 3.
The current ratio can be improved to 2.5: 29.8 or the like.
The bottom wavelength is four times the product of the film thickness and the photorefractive index, and the bottom wavelength can be moved within the visible range (390 nm to 680 nm) by changing the film thickness. However,
Since the reflection color due to the interference of the film changes due to the movement of the bottom wavelength, it is preferable to carry out in the wavelength range of 490 nm to 630 nm. Therefore, the allowable range of the film thickness is 75 nm to 94 nm for the first transparent film and 8 for the second transparent film.
Each should be selected in the range of 5 nm to 106 nm.

In the above-described embodiment, the first and second composite layers each have two layers, but they may have three or more layers. Also, the first of the second composite layer
The translucent film 6 may not have conductivity.

[0019]

As described above, according to the present invention, not only a picture tube having a good light reflection reducing effect can be obtained with good productivity, but also an antistatic effect can be obtained. In a color picture tube, it is possible to improve the current ratio when obtaining white balance.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part of a composite face panel of a picture tube embodying the present invention.

FIG. 2 is a spectrum diagram of light reflection on the outer surface of the face panel of the same picture tube.

[Explanation of symbols]

 1 Glass substrate 2 1st composite layer 3 2nd composite layer 4,6 1st translucent film 5,7 2nd translucent film

Claims (1)

[Claims] 1. A first composite layer provided on the outer surface of a glass substrate forming a face panel, and a second composite layer provided on the inner surface of the glass substrate, each of which comprises a light source of the glass substrate. A first translucent film having a light refractive index higher than the refractive index, and a second light transmissive film provided on the first translucent film and having a light refractive index lower than the light refractive index of the glass substrate. Have
At least the first light-transmitting film of the first composite layer has conductivity, and the picture tube is characterized in that.