KR20000050778A - fluorescent screen strueture of cathode ray tube - Google Patents

Abstract

PURPOSE: A fluorescent screen of a color cathode ray tube is provided to improve contrast and brightness. CONSTITUTION: A fluorescent screen of a color cathode ray tube includes a glass panel(1) on which a black matrix layer(2) is formed. In addition, three fluorescent layers, namely, double red layers(13a,13b), double blue layers(14a,14b), and a single green layer(15) are formed on the glass panel(1). In particular, a lower red layer(13a) and a lower blue layer(14a) have a smaller reflexibility than an upper red layer(13b) and an upper blue layer(14b), respectively. The lower layers(13a,14a) with low reflexibility have a high contrast, whereas the upper layers(13b,14b) with high reflexibility have a high brightness. Furthermore, there is a thirty percent or more difference between the lower layers(13a,14a) and the upper layers(13b,14b) in 500nm wavelength range in the case of the red layers(13a,13b) or in 600nm wavelength range in the case of the blue layers(14a,14b).

Description

Fluorescent film structure of color cathode ray tube {fluorescent screen strueture of cathode ray tube}

The present invention relates to a fluorescent film structure of a color cathode ray tube, and in particular, a low reflection fluorescent film with many pigments is formed as a lower layer, and a fluorescent film having high reflectance is formed as an upper layer due to large particles and little or no pigment adhesion, thereby forming contrast and luminance. The present invention relates to a fluorescent film suitable for simultaneously improving.

The fluorescent film formed on the inner surface of the panel of the conventional image display device is a red phosphor 4 (red phosphor-pigment amount) having a small amount of pigment 3 attached to the inner surface of the panel 1 on which the black matrix film 2 is formed as shown in FIG. : 0.05 to 0.1 wt% pigment / phosphor, reflectance: reflectance is about 80% at 620 nm, the wavelength range of red color of visible region, 50 to 60% at 500 nm, and blue phosphor 5 (blue phosphor-pigment amount: 0.8 ~ 1.2wt% pigment / phosphor, reflectance: reflectance is about 80% at 450nm, the wavelength range of blue color in the visible region, 45 ~ 50% at 600nm) and green phosphor which does not adhere pigment in consideration of luminance loss ( 6) (Reflectivity: 90% or more at the line wavelength) to apply a certain thickness to form a red fluorescent film, blue fluorescent film, green fluorescent film.

In the above structure, the green phosphor generally does not have a pigment to prevent luminance and loss. However, since the green phosphor exhibits high reflectance in the full-wavelength region of visible light as shown in FIG. Due to the high reflectance at, the contrast decreases due to external light.

In order to compensate for this, the transmittance of the panel is adjusted, but the adjustment of the transmittance of the panel uniformly lowers the overall transmittance in the electric field, thereby improving the contrast, but causing a large decrease in the characteristics of the luminance.

Since the pigment has a high transmittance in the wavelength region and a low transmittance in the other region, it is possible to prevent a decrease in contrast due to external light while maintaining a high brightness of about 90% rather than adjusting the transmittance of the panel.

However, the red and blue phosphors using a small amount of pigment as described above cannot sufficiently prevent external light reflection, so the effect of improving contrast is reduced.

As shown in Figs. 4B and 4A, the reflectance is about 30 to 40% lower than that of the other wavelength bands except for the wavelength bands of red (Fig. 4B) and blue (Fig. 4A).

However, since the reflectance of 15 to 25% is lowered in the wavelength range of emitting color, the lowering of luminance occurs.

In particular, the red phosphor and the blue phosphor to which the pigment is attached as in the conventional art are in a state in which the pigment is attached to the phosphor and dispersed in the phosphor layer as a whole, so that not only the lower portion of the phosphor layer but also the phosphor of the upper portion 3a (5a) Also lowers the luminance.

Therefore, in order to improve the contrast by lowering the reflectance of external light entering through the panel, the pigment is concentrated in the lowermost part (3b) (5b) of the phosphor layer, which is the innermost part of the panel, and evenly positioned inside the panel to reflect the external light. Should be lowered.

However, in the conventional fluorescent surface, the lower part of the phosphor layer is insufficient in the amount of pigment, so that the external light reflectance is not sufficiently lowered, and the contrast effect is lowered. The phosphor having a small amount of pigment is scattered throughout the phosphor layer, so the luminance of the upper phosphor Decreases.

Pigments attached to the phosphor in the upper portion of the phosphor layer lower the luminance of the phosphor, but because the phosphor in the lower layer in between the panel and the external light coming in contact with the external light, it cannot play a role in reducing the reflection of the external light. Can't improve contrast

As such, when the pigment is added to improve the contrast and the transmittance of the panel is adjusted, the luminance is lowered, so it is difficult to satisfy both of these characteristics.

An ideal fluorescent surface is advantageous in screen characteristics in that the lower phosphor should have a large amount of pigment attached thereto, and in the upper layer, the lower phosphor should not have a pigment that lowers the brightness.

In the US patent of this concept (No: 3,886,394 / RCA / 1975), a green phosphor layer is formed as a single coating as shown in Fig. 2, and the red phosphor layer 8 and the blue phosphor layer 9 are applied in two layers. At this time, (7a) and (7b) is a lower layer of the red phosphor layer and the blue phosphor layer, respectively, and a color filter corresponding to each color is attached to cover about 20 to 80% of the surface of the phosphor.

At this time, red and blue phosphors of 7 to 12 µm are attached to the surface of the phosphor using a color filter of 0.1 to 0.5 µm.

In the above-mentioned US patent, the red and blue phosphors formed in the upper layer of the claim are fixed without a filter attached, and therefore, do not expect a case where a small amount of pigment is attached. It only specifies the presence and degree of pigmentation of the lower and upper layers of red and blue, but the double coating is applied without revealing the degree and exact value of reflectance according to the wavelength band affecting the characteristics. And the surface structure of the phosphor is not secured.

Therefore, the difference in reflectance in the areas of the upper and lower layers of red and blue (red: 610-630 nm, and the blue: 430-470 nm) is important, and the areas of no color (red: 500). Nm, blue: 600 nm), the U.S. Patent does not distinguish this and does not specify the reflectance according to the wavelength of the pigment, and only specifies the degree of adhesion to the surface at the surface of the phosphor, It does not have the effect of patent because it is not an optimal partner to improve the characteristics without specifying the characteristics of reflectance.

Meanwhile, in the European Patent Publication (EPO742575A, Toshiba), color filter layers 10a, 11a, and 12a, which are fine particles in units of 40 to 70 nanometers (nm), are first formed on an inner surface of a panel in order to increase the contrast effect as shown in FIG. Red (10), blue (11), and green phosphor (12) are applied thereon to form a fluorescent surface.

At this time, the component of the color filter layer, red is iron oxide (F _e2 O ₃ ) -based, green is cobalt green (TiO ₂ -nIo-CoO-ZnO) system, blue is composed of cobalt blue (Al ₂ O ₃ -CoO) system do.

FIG. 3 shows that when the transmittance of the panel is adjusted to improve contrast, the transmittance at all wavelengths is lowered, thereby lowering the luminance. Therefore, the transmittance is increased in the wavelength region where a specific color is used to act as a pigment, and low transmittance in other regions. It is a method of forming a color filter layer having a first on the inner surface and a phosphor layer thereon

However, in the European patent as shown in FIG. 3, the particles of the color filter are very fine in units of 40 to 70 nanometers, so that the dispersion of the color filter is difficult, so that uniform coating on the panel is difficult.

Therefore, a difference in luminance may occur due to a difference in transmittance at each local place in the panel, thereby reducing brightness uniformity.

In addition, since the color filter layer is a color filter controlling only the transmittance, if only the color filter layer is applied without the phosphor, there is no light emission by the energy layers, and thus the luminance cannot be increased.

And even if a color filter is used as shown in Figs. 5A to 5C, the transmittance decreases by 30 to 40% even in the region of the wavelength of the designated color, so that the luminance decreases in parallel.

In addition, the color filter is expensive, and in addition to the facility for applying the phosphor, there should be a facility for applying the color filter separately, which is a factor in lowering productivity and increasing equipment-related costs.

The color filter is a material having a completely different physical properties and constituents than the phosphor, and thus, the color filter has a problem due to difficulty in process control and material control, which causes a defect and lowers the production yield.

In addition, since the color filter has 40 to 70 nanometers of particles, it is very fine and difficult to disperse, and thus cannot reproduce what is left after one use.

The present invention is to solve the above-mentioned conventional problems, when forming a red and blue fluorescence surface in a multi-layer lower layer of a low reflection phosphor attached to the pigment than a general phosphor, and a small amount of pigment attached or not attached The purpose of this is to obtain a suitable fluorescent film which can produce high contrast and high brightness by using a phosphor as an upper layer.

1 is a conventional fluorescent surface structure diagram

2 is another conventional fluorescent surface structure diagram

Figure 3 is another conventional fluorescent surface structure diagram

4A is a graph showing the spectral reflectance of a blue phosphor

4b is a graph showing the spectral reflectance of a red phosphor;

4E is a graph showing the spectral reflectance of a green phosphor

5A is a graph showing the transmittance of a red color filter

5B is a graph showing the transmittance of the green color filter

5C is a graph showing the transmittance of a blue color filter

5C is a graph showing the transmittance of a blue color filter

6 is a fluorescent surface structure diagram of the present invention

Figure 7 is a fluorescent surface forming process chart of the present invention

Explanation of symbols for the main parts of the drawings

13a: primary red phosphor layer 13b: secondary red phosphor layer

14a: primary blue phosphor layer 14b: secondary blue phosphor layer

15: green phosphor layer

According to the present invention for achieving the above object, in the fluorescent film of a color cathode ray tube using red, blue, and green phosphors, the red phosphor layer and the blue phosphor layer are each made of multiple layers, and the lower layer has a lower reflectance than the upper layer, and the red phosphor. In the case of 500 nm and the blue phosphor, the reflectance of the phosphor formed in the lower layer and the upper layer in the wavelength band of 600 nm is composed of the fluorescent film of the color cathode ray tube, characterized in that the difference is more than 30%.

FIG. 6 is a diagram illustrating a structure of forming a fluorescent film according to the present invention, in which a single phosphor layer is formed by multi-coating with phosphors having different structures when forming a fluorescent surface to simultaneously improve luminance and contrast.

In more detail, the present invention relates to a low-reflective phosphor (a red phosphor-pigment: 0.2 to 0.5 wt% pigment / phosphor, reflectance: visible wavelengths in which the visible region emits red light) to which 4 to 5 times more pigments are attached than a general phosphor. Reflectance is about 70-90% at 620nm, 15-10% at 500nm) (Blue phosphor-pigmentation: 3-6wt% pigment / phosphor, reflectance: Reflectance 70 at 450nm, the wavelength band of blue color in the visible region It is about 90%, and at 600 nm, (15 to 40%) is applied to the inner surface of the panel with phosphors having a constant thickness (lower layer: thickness of 1 to 1.5 times the average particle size of phosphor) on the lower layer of the phosphor layer. This ensures high contrast.

As such, the average particle size is 3 to 15% larger than the primary coated phosphor of the lower layer on the lower layer forming the primary red phosphor layer 13a and the primary blue phosphor layer 14a. A second phosphor having a high luminance (reflectance: 75 to 95% or more at full wavelength) is applied at a predetermined thickness (upper layer: 1 to 2.5 times the thickness of the average particle size of the phosphor) and the upper secondary red phosphor layer 13b. The secondary blue phosphor layer 14b is formed to have high brightness.

In this case, each lower layer of the red phosphor layer and the blue phosphor layer has a lower reflectance than the upper layer, and the lower layer and the lower layer in the wavelength band of 500 nm for red and 600 nm for blue, respectively, which are wavelength bands other than the wavelength range of the corresponding color. The reflectance of the phosphor forming the upper layer is characterized by having a difference of 30% or more.

In the phosphor forming the lower layer, the red phosphor may attach 0.1 wt% or less of the pigment, and the blue phosphor may attach 2 wt% or less of the pigment.

In forming the above-described fluorescent film, as shown in FIGS. 6 and 7, after forming the black matrix film 2 on the panel 1 and forming the phosphor layer of three colors (red, green, blue), the pigment is not attached first. The green phosphor (reflectance: 85% or more in the electric field) is made into a slurry by adding other chemicals to form a green phosphor layer 15.

Subsequently, red and blue phosphor layers are formed. First, low-reflective phosphors to which 4 to 5 times more pigments are attached than ordinary phosphors (pigment amount: red phosphor 0.2 to 0.5 wt% pigment / phosphor, blue phosphor 3 to 6 wt% pigment) / Phosphor) was prepared by adding a photosensitive agent, a surfactant and other additives to prepare a phosphor slurry, and applied to a constant thickness (1 to 1.5 times the thickness of the average phosphor size), the primary red phosphor layer (13a) which is the lower layer of the phosphor layer ) And the primary blue phosphor layer 11a are formed.

In this way, a lower layer forming a low reflection phosphor layer is formed on the inner surface of the panel at a constant thickness.

On top of that, the average particle size is 3-15% larger than the phosphor applied on the lower layer, and red or blue phosphors with little or no pigment (reflectance: 80-95% or more in full-wave) are used as photosensitive agents and surfactants. To prepare a phosphor slurry to form a secondary red phosphor layer 13b and a secondary blue phosphor layer 14b, which are upper layers of the phosphor layer, with a predetermined thickness (thickness of 1 to 2.5 times the average particle size of the phosphor). .

The following is described according to the embodiment.

① First, form a black matrix film on the panel.

② A green phosphor layer is formed by preparing a slurry with little or no pigment (reflectance: 80% or more at full wavelength, 6.5㎛ particle average size) by adding other chemicals.

(3) Blue low-reflective phosphor (blue phosphor-pigment amount: 4 to 5 wt% pigment / fluorescent agent, reflectance: reflectance is about 75 to 85% at 450 nm, which is the blue band in the visible region, and 30 to 35% at 600 nm. The average particle size of 6.5 μm was added to the other chemicals to form a slurry to form a lower layer of the blue phosphor layer at a constant thickness (thickness of 1 to 1.5 times the average particle size of the phosphor).

④ Red low reflection phosphor (red phosphor pigment amount: 0.3 to 0.4 wt% pigment / phosphor, reflectance: reflectance is about 75 to 85% at 620 nm, which is the wavelength band of red in the visible region, and 25 to 40% at 500 nm) To the other drugs are added to prepare a slurry to form a lower layer of the red phosphor layer to a certain thickness (1 to 1.5 times the thickness of the average phosphor size).

⑤ A blue phosphor having no pigment attached (emissivity: 90-95% or more at full-wavelength, average particle size of 702㎛) was added to other chemicals and prepared as a slurry to obtain a certain thickness (1 to 2.5 times the thickness of the average phosphor size). ) To form an upper layer of the blue phosphor layer.

⑥ Red phosphor with no pigment (reflectance: 90 ~ 95% at full wavelength, average particle size of 702㎛) was added to other chemicals to make a slurry and thickness of 1 ~ 2.5 times the average particle size of phosphor ) Forms an upper layer of the red phosphor layer.

<Table 1> SLURRY composition

Phosphor Underlayer Slurry Phosphor upper layer slurry medicine Amount medicine Amount Pure water (including additional pure water) 340ml Pure water (including additional pure water) 340ml 10% PVA solution 90 ml 10% PVA solution 100 ml 5% SDC solution 15 ml 5% SDC solution 16 ml Other additives (dispersant, defoamer, sensitizer) 15 ml Other additives (dispersant, defoamer, sensitizer) 15 ml Fluorescent agent (low reflection phosphor) 250 g Fluorescent material (Phosphor without pigment) 260 g Total 710 ml Total 731 ml

<Example: fluorescence measurement applied tube measurement data of the present invention>

comparison target :

-Fig. 6 of the present invention: lower layer (primary coating): red, blue 6.5 µm low reflection phosphor

(Red phosphor 0.4wt% pigment / phosphor, blue phosphor 5wt pigment / phosphor)

Rust 6.5㎛ unattached phosphor

Upper layer (secondary coating): Red, green, blue 7.2 μm phosphor without pigment

Conventional fluorescent surface, <FIG. 1>: red, blue 6.5 micrometer fluorescent substance with pigment

(0.05 to 0.1 wt% red phosphor, fluorescent agent 0.8 to 1.2 wt% pigment / fluorescent agent)

Rust Phosphor 6.5㎛ Unattached Phosphor

Color filter application <Figure 3>: formation of red, blue and green color filter layers

Red, Blue, Green 6.5㎛ Pigment with no pigment

Panel condition: same panel transmittance

1) luminance comparison

Condition: Measurement point-Center, White (color coordinates 0.281, 0.311) relative

Current applied This invention <FIG. 6> Conventional fluorescent surface <FIG. 1> Color filter application <Fig. 3> 200㎂ 105.8% 100.0% 91.2% 400 yen 105.9% 100.0% 90.9% 600㎂ 106.1% 100.0% 60.8% 800㎂ 106.0% 100.0% 90.6%

2) Contrast Comparison

Outside light intensity (Lux) The invention (Fig. 6) Conventional fluorescent surface (Fig. 1) Application of color filter (Fig. 8) 0 113.8% 100.0% 115.2% 100 113.9% 100.0% 115.9% 300 114.1% 100.0% 115.8% 500 114.0% 100.0% 115.6%

As described above, the present invention is to form a fluorescent surface of the multiple phosphor layer in order to improve the brightness and contrast, a low-reflective phosphor is attached to the inner surface of the panel with a low-reflective phosphor attached to 4 to 5 times more pigment than a general phosphor. By forming the film, the contrast enhancement effect of the pigment is 15% higher than that of the related art, and a small amount or no adhesion of the pigment causing the deterioration of the brightness is formed so that the upper layer of the phosphor layer is formed as a phosphor having high brightness. It can improve 5 to 10%.

In addition, the fluorescent surface of the present invention forms a lower layer as a low-reflective phosphor that plays a role as a contrast enhancement instead of the color filter layer compared to the conventional fluorescent surface to which the color filter of FIG. 3 is applied, thereby achieving a high luminance of 10 to 15% in characteristics of equivalent contrast. In addition, the particles are large and the dispersion is better than the color filter, and the coating properties are excellent.

In terms of price, it is advantageous over color filters, and both upper and lower layers of the phosphor layer are advantageous in terms of production, process, equipment, and material management.

At this time, since the size of the particles coated on the upper layer is larger than the size of the phosphor applied on the lower layer, mixing and mixing of other colors are reduced, and energy lost without emitting light is reduced, thereby improving the luminance.

And since the particles are large and well dispersed, the remaining phosphors can be regenerated, thus greatly reducing the production cost.

Claims (5)

In the fluorescent film of a color cathode ray tube using red, blue, and green phosphors, the red layer and the blue phosphor layer each have multiple layers, and the lower layer has a lower reflectance than the upper layer, and the red phosphor has a wavelength range of 500 nm and a blue phosphor. The fluorescent film structure of the color cathode ray tube, characterized in that the reflectance of the phosphor formed in the lower layer and the upper layer in the wavelength band of 600nm is more than 30%. The method of claim 1, A fluorescent film structure of a color cathode ray tube, characterized in that the phosphor forming the lower layer and the upper layer has a reflectance of 70% or more in the wavelength region showing the emission peak of the corresponding color. The method of claim 1, The pigment adhesion amount of the fluorescent substance which forms the lower layer of a red fluorescent substance layer is 0.2-0.5 wt% of phosphor inside ratios, The fluorescent film structure of the color cathode ray tube characterized by the above-mentioned. The method of claim 1, Pigment adhesion amount of the phosphor forming the lower layer of the blue phosphor layer is 36wt% compared to the phosphor, the fluorescent film structure of the color cathode ray tube. The method of claim 1, The red phosphor, which forms the upper layer of the red and blue phosphor layers, has a pigment of 0.1 wt% or less attached, and the blue phosphor has a pigment of 2 wt% or less.