KR0150507B1 - Cathode ray tube with glare reducing, neutral density faceplate coating and process - Google Patents

Abstract

The cathode ray tube 21 has a face plate panel 27 having a surface reflection reducing neutral density coating film on its outer surface. The coating film contains a lithium silicide material, at least two light attenuating materials and an appropriate amount of abrasion resistance material, wherein the abrasion resistance material is added as a separate component or mixed with the light attenuation material. The light attenuating material is selected from the group consisting of carbon black slurry, black ink, blue ink, black dye and blue dye. Also described is a method of forming a coating film.

Description

Method of forming such a coating on a cathode ray tube and faceplate panel having an anti-glare neutral density coating

1 is a partial longitudinal sectional view of a cathode ray tube according to the present invention;

FIG. 2 is an enlarged cross sectional view of a cathode ray tube face plate along line 2-2 of FIG.

3 is a graph of spectral reflectance versus wavelength for multiple faceplate panels with uncoated control panels and many other panels with new coatings at different mixture levels.

4A-4C are spectral reflectance graphs for each wavelength of 440 nm, 550 nm and 600 nm as a function of reflection angle.

* Explanation of symbols for main parts of the drawings

21 cathode ray tube 27 glass faceplate panel

31 fluorescent screen 37 glare reduction neutral density coating film

39: outer surface of the faceplate panel

The present invention relates to a cathode ray tube having a neutral density coating film for reducing glare on the outer surface of a cathode ray tube (CRT) faceplate panel, and more particularly to a method of forming such a coating film.

The neutral density coating on the outer surface of the cathode ray tube (CRT) faceplate panel is a low cost component that can replace dark glass faceplates and is effective in increasing the contrast of the image displayed on the cathode ray tube. Methods for imparting antiglare properties to neutral faceplate coatings are well known in the art and are disclosed, for example, in US Pat. No. 3,898,509 to Brown et al., 1975.8.5. In this patent, a coating liquid consisting of india ink containing about 4% by weight (wt.%) Carbon and lithium polysilicate is sprayed onto the outer surface of the CRT face plate, so that the whole of the face plate The light transmittance is reduced to 69% (42% in uncoated) to provide glare reduction. The light transmittance reduction effect varies with the amount of light attenuating material of the coating compound.

As used herein, the term glare reduction refers to a reduction in luminance and resolution for a reflected image of an ambient light source. The glare from the ambient light source disturbs the viewing of the image on the cathode ray faceplate, which is offensive to the viewer.

U. S. Patent No. 3,940, 511 to Deal et al., 1976.2.24, discloses a coating compound similar to that described in U. S. Patent No. 3,898, 509, cited above, which compensates for the undesirable color tone of the coating by the carbon particles of the coating. Or by adding a color correction dye to provide the desired color tone to the coating.

A drawback for each neutral density coating film disclosed in the above cited patent is that the coating film contains pigments that reduce mechanical and chemical strength. Therefore, the coating film has a low abrasion resistance and is easily damaged by surrounding elements.

The task of the present invention regarding a method of forming a neutral density coating film by forming a coating liquid with a minimum of organic additives and a binder in addition to a wear resistant material is to reduce the likelihood of the coating film being easily affected by surrounding damage factors, and to reduce the spectral reflectance within a range. It is easy to get.

The cathode ray tube according to the present invention includes a face plate panel having an outer surface having an anti-glare neutral density coating film. The coating film contains a lithium silicate material, at least two light attenuating materials and a saving abrasion resistant material, wherein the abrasion resistant material is mixed with the light attenuating material or provided as a separate component. The light attenuable material is selected from the group consisting of carbon black slurry, black ink, blue ink, black dye and blue dye. The present invention also includes a method of applying the coating liquid to the faceplate panel.

The present invention is explained in more detail with reference to the accompanying drawings.

The cathode ray tube 21 shown in FIG. 1 has a vacuum glass envelope having a funnel portion 25 and an integral neck portion 23. The glass faceplate panel 27 is coupled to the funnel portion 25 through an opaque glass seal 29. A fluorescent screen 31 formed of fluorescent inferiority is provided on the inner surface of the face plate panel 27. As shown in detail in FIG. 2, for example, a light reflective metal film 33 such as aluminum is deposited on the fluorescent screen 31. The shape screen 31 may generate a fluorescent image that can be viewed through the faceplate panel 27 when scanned by the electron beam of the electron gun 35. A new glare reduction neutral density coating 37 is provided on the outer surface 39 of the faceplate panel 27 to improve the contrast of the image viewed through the faceplate panel 27.

The anti-glare neutral density coating 37 is similar to the anti-glare coating disclosed in US Pat. No. 4,965,096, issued to Deal on October 23, 1990, but the new coating is more wear resistant than prior art coatings without colloidal silica. It differs in that it contains an appropriate amount of colloidal silica that develops resistance.

The outer surface 39 of the faceplate panel 27 of the sealed vacuum cathode ray tube 21 is first. One of the well-known scouring and cleaning methods used to remove lint, oil, debris and the like is carefully cleaned to avoid scratching the outer surface of the faceplate panel. It is preferable to scrub the outer surface of the faceplate panel with an industrial scouring mixture and then rinse with water. The outer surface is etched by swabbing with 2-8 wt.% Ammonium bifluoride solution and then rinsed with deionized water and dried using an air curtain to prevent water marks. The faceplate panel is heated at about 30-80 ° C. by an oven or other suitable means and coated with an aqueous solution of lithium polysilicate and an appropriate amount of wear-resistant material and at least two light-damping materials, the wear-resistant material being light It is provided as a constituent of the damping material or as a separate component of the coating film and the light dampening material is selected from the group consisting of carbon black slurry, black ink, blue ink, black dye and blue dye. Lithium polysilicate is a lithium-stabilized silica sol having a SiO ₂ to LiO ₂ ratio between about 4: 1 to 25: 1. The sol is substantially free of ions other than hydroxyl. The lithium stabilized silica sol is substantially different from lithium silicate solution, which is a solvent dissolved compound. The lithium-sol coating solution is dried after secondary heating to form a lithium silicate coating film. The coating film may be provided in one layer or several layers by a conventional process such as spraying. The coating film is dried in air and then heated to a temperature of 15 to 60 ° C. higher than the ambient temperature (about 22 ° C.). The coating film is washed again for 15 to 60 seconds with warm water at about 50 to 60 ℃. The coating is carefully dried in the atmosphere by preventing lint or other foreign particle deposition on the coating.

The coating film has a property of reducing glare, that is, a property of scattering reflected light, and at the same time improves image contrast and abrasion resistance of a coating film containing no wear-resistant material.

Example 1

In order to remove dust, oil, debris and the like, the outer surface 39 of the vacuum CRT 21 face plate panel 27 is cleaned by a conventional scouring method and a cleaning method. The outer surface is slightly etched with 5 wt.% Ammonium difluoride solution and washed with deionized water. The faceplate of the CRT is then heated in the range of 30-80 ° C. and spraying a fresh liquid coating mixture on the warm glass faceplate surface. The coating mixture is formed by mixing the following components.

: 28.4 g (10.4 wt.%) Of lithium polysilicate 48 and 0.6 g (0.2 wt.%) Of black dye, available from EI DuPont Company, Wilmington DE., CDI Dispersions, Newark, 29 g (10.6 wt.%) Of colored mixture sold by N. J

15 g (5.5 wt.%) Of carbon slurry to be described later

228.5 g (83.9 wt.%) Of water

The carbon slurry used to form the coating described above contains the following materials.

: 0.3 wt.% Surfactant, such as Brij 35 SP available from ICI America Inc., Wilmington, DE,

: Ligno Tech. 1.2 wt.% Dispersion medium such as Marasperse CBA-1 or CBOS-3, available from USA, Greenwich, CT,

1.5 wt.% Basic solution such as: 30 wt.% Ammonium hydroxide

4.4 wt.% Carbon, such as BP-1300, available from Cabot Corp., Waltham, MA.

7.5 wt.% Colloidal silica, such as Ludox, AM, available from E. I. DuPont Company, Wilmington DE, for increasing wear resistance.

Remaining amount of deionized water

The coating solution is dried in the air and then heated to further cure. If an infrared heater element such as a Calrod heater is used, the glass surface is heated for 2-4 minutes at a temperature of 15-60 ° C. above ambient temperature. However, when an oven is used to heat the glass surface, the cathode ray tube is placed in the oven for 15-30 minutes or until the oven temperature reaches 85 °. The cathode ray tube is then washed with warm deionized water (50-60 ° C.) for about 15-60 seconds and then dried.

Example 2

The first coating mixture is formed by mixing the following components.

29 g (10.6 wt.%) Of polysilicate 48 and black dye mixture sold as CDI BS15188 described in Example 1.

24.5 g (9 wt.%) Of carbon slurry as described in Example 1

219 g (80.4 wt.%) Of water

The coating solution was applied and dried in the manner described in Example 1 to provide a DARK 70 GLOSS coating film on the outer surface of the face plate.

Example 3

The third mixture is formed by mixing the following components.

29 g (10.6 wt.%) Of CDI BS15188 as described in Example 1

39.5 g (14.5 wt.%)) Carbon slurry as described above

204 g (74.9 wt.%) Of water

The coating solution was applied and dried in the manner described in Example 1 to provide a DARK 70 GLOSS HC (High Contrast) coating film.

Example 4

A control coating that does not contain any dark pigments but provides a standard Aniti-Glare (STD AG70 GLOSS) coating film is provided by mixing the following ingredients.

: E. 28.4 g (10.4 wt.%) Polysilicate 48, available from I. DuPont Company, Wilmington, DE.

244.1 g (89.6 wt.%) Of water

In the coating liquid according to the present invention, the concentration of lithium lollysilicate 48 can vary from 1 to 20 wt.% But preferably from 8.86 to 10.5 wt.%, While the concentration of black slurry can vary from 1 to 30 wt.%. It is desirable to vary from 5.5 to 14.5 wt.%. In addition to the black dye, which can vary from 0.1 to 0.4 wt.%), About 0.03 wt.% Of the blue dye can be added to the mixture to remove the brown tint caused by carbon. This blue dye is blue methylene that is readily available from many sources.

In FIG. 3, the spectral reflectances for the selected coatings among the new coatings are shown as a group of curves, and the uncoated faceplate representing the reference value is shown as curve 1. Curve 2 shows a standard anti-glare coating that does not contain a dark dye, formed according to the treatments described in the above cited US Pat. No. 4,965,096 and Example 4. Curves 3 and 4 represent the coating films made according to the new coating film formation methods of Examples 3 and 2 described above, and differ only in the content of the carbon black slurry. Curve 3 with higher reflectivity in the wavelength range of about 400-625 nm includes about 14.5 wt.% Of carbon black slurry, while curve 4 with lower reflectance in the same wavelength range shows 9.0 wt.% Of carbon slurry. Has content. From this curve, the percentage of spectral reflectance includes the carbon slurry content contained in forming the coating film.

Example 5

In order to increase the abrasion resistance, a coating film using a black ink mixed with other inks or dyes other than the carbon black slurries of Examples 1 to 3 and an appropriate amount of colloidal silica was also evaluated. The method of providing and applying the faceplate panel outer surface 39 for coating is the same as that described with respect to Example 1. An example for the fifth coating is made by mixing the following ingredients.

40.7 g (12.8 wt.%) Polysilicate 48

: 22.8 g (7.2 wt.%) Of super black ink sold by Hunt Manufacturing, Statesville, NC

: 3.2 g (1 wt.%) Blue ink available from Pelikan AG, Hanover, Germany.

64 g (2 wt.%) Colloidal silica (Ludos AM)

244 g (remaining amount) of deionized water

Example 6

The sixth coating compound is formed by mixing the following components.

4.07 g (13.7 wt.%) Of CDI BS 15188 containing 38.9 g (13.4 wt.%) Of polysilicate 48 and 0.8 g (0.3 wt.%) Of black dye (CDI BS15188).

6.0 g (2 wt.%) Of super black ink

: 6.4 g (2.1 wt.%)) Colloidal silica (Ludox AM)

245 g (remaining amount) of deionized water

Example 7

The following coating solution is a control for the black ink composition and does not contain any colloidal silica. The ink coating liquid contains the following components.

4.07 g (13.6 wt.%)) Of polysilicate 48

11.4 g (3.8 wt.%) Super black ink

4.0 g (1.3 wt.%) Of black ink

: 244 g (rest of water)

The ink coating liquids of Examples 5 to 7 are dried and cured by heating the glass surface containing the coating liquid to about 100 ° C. instead of 15 to 60 ° higher than the ambient temperature as in the case of the coating liquid of Example 1. The washing and drying steps are the same as described in Example 1.

4A to 4C show the coating film based on the ink of Example 5, the carbon black slurry coating film of Example 1, and each of the uncoated faceplates provided as a reference, for 440 nm, 550 nm and 600 nm wavelengths, respectively. A comparison of the spectral reflectances is shown as a reflection angle function. The vertical axis of each figure is an arbitrary parameter but represents the relative reflectance for each coating film and the reference plate panel.

The test results comparing the conventional anti-glare coating films as in Example 4 without the coloring step to provide a neutral density distribution with the coating films of Examples 1 and 5 are shown in the following table. In the table, the Glossiness item is a measure of glare at 60 ° from the vertical using gloss. Values in the range 0-100 represent the percentage (%) of unscattered reflected light. Buff is a polycarbonate test block with an increase in visible light during surface reflectance, i.e. Al ₂ O ₃ glare applied to the coated faceplate of the cathode ray tube, with a load of 10 g / cm2 (front and back) Glossy spots that occur when rubbing around the same area. Each front and back motion, i.e. each cycle is defined as 1X. Scuff is a visible wear line. The coating surface to be worn is inspected for evidence of wear during the: muff: test. The light output in footlamberts / milliampere (FL / mA) is white light output at an equivalent color temperature of 6500 ° Kelvin (K). TFR is cathode ray tube surface reflectance and is measured with a spectroradiometer which compares the spectral reflectance of the cathode ray tube under test with the calibration standard. Contrast Ratio The ratio of the maximum value to the minimum luminance value at 25 footcandles (fc). The R / B and R / G current ratios are the ratio of the relative amounts to the current of each of the incident primary color components to obtain a selective white point on the CIE diagram at a color temperature of 6500K. SR is a specular reflectance representing the value of reflectance measured at an angle of incidence of 13.5 ° using a gonioreflectometer. This value represents the percentage of incident light that is specularly reflected.

While the change in measurement parameters between the sample coatings is evident in the table, the buff and scuff tests demonstrate that the conventional uncolored anti-glare coating of Example 4 is the most resistant to abrasion. However, the carbon slurry coating liquid of Example 1 having a colloidal silica concentration of 7.5 wt.% Has better abrasion resistance than the black ink coating liquid of Example 5, and the black ink coating liquid of Example 5 has a lower colloid concentration than other coating liquids. Silica and a higher concentration of coloring mixture than Example 1.

Claims (9)

A cathode ray tube having a face plate panel (37) having an outer surface having an anti-glare neutral density coating film, the coating film (37) comprising: a lithium silicate material; At least two light-damping materials selected from the group consisting of carbon black slurries, black inks, blue inks, black dyes and blue dyes, and wear-resistant materials added as a separate component or as a component of the light-damping material. Cathode ray tube, characterized in that it contains 0.07 to 2.4wt% colloidal silica. In a cathode ray tube having a face plate panel having an outer surface having an anti-glare neutral density coating, the coating film 37 includes 1 to 20 wt.% Of lithium polysilicate, 1 to 30 wt.% Of carbon black slurry, and 0.1 to 0.4 wt. A cathode ray tube, characterized in that it contains.% Of black dye and the remaining amount of water. The cathode ray tube according to claim 2, wherein the coating film (37) further contains about 0.2 to 0.4 wt.% Of blue dye. 3. The carbon black slurry according to claim 2, wherein the carbon black slurry is 7 to 8 wt.% Colloidal silica, 4 to 5 wt.% Carbon, 1 to 1.5 wt.% Dispersion medium, 1.4 to 1.6 wt.% Basic solution as a wear resistant material. And 0.2 to 0.4 wt.% Of a surfactant and a residual amount of deionized water. The cathode ray tube according to claim 4, wherein the basic solution is a 30% aqueous solution of ammonium hydroxide. A cathode ray tube having a face plate panel having an outer surface having a neutral surface coating film, the coating film 37 comprising: a lithium polysilicate material; 1 to 2.1 wt.% Colloidal silica as an abrasion resistant material; A cathode ray tube, characterized in that it contains at least two light attenuating materials selected from the group consisting of black ink, blue ink and black dye. 7. The coating film (37) according to claim 6, wherein the coating film (37) is made of 0.2 to 1.5 wt.% Of the agent selected from the group consisting of 8 to 15 wt.% Of lithium polysilicate 1 to 8 wt.% Of black ink, blue ink and black dye. A cathode ray tube, characterized in that it further contains a coloring agent and a residual amount of water. CLAIMS 1. A method for forming an anti-glare neutral density coating film on an outer surface of a cathode ray tube faceplate panel, the method comprising: a) cleaning the outer surface (39); b) etching with the outer surface 2-8% NH ₂ F ₂ H solution for 10-80 seconds; c) heating the outer surface to a temperature in the range of 30 to 80 ° C. and d) coating the outer surface with an anti-glare neutral density coating film containing abrasion resistant material (37); e) drying the coating film; f) heating said outer surface with said coating film to a temperature of about 15-100 ° C. above ambient temperature for a time sufficient to cure the coating film as a whole; g) washing the coating film with 50 to 60 ° C. water for about 15 to 60 seconds; h) glare reduction neutral density coating film forming method comprising the step of drying the coating film. 10. The method of claim 8, wherein the temperature in said heating step f) is between 15 and 60 < 0 > C.