JPS6047583A - Color projection type video device - Google Patents

Abstract

PURPOSE:To eliminate trouble in the process of painting a fluorescent screen and improve the precision by using one of fluorescent materials shown by a general formula LnOCl:xA for the green luminous component of a color projection type video device, and covering this fluorescent material with one of zinc silicate and aluminum silicate. CONSTITUTION:Lenses 4R, 4G, and 4B for adjustment are arranged in front of the surfaces of cathode-ray tubes 1R, 1G, and 1B which have fluorescent screens luminescing in red, green, and blue respectively, and light corresponding to each luminescence color is adjusted and projected on a screen 5, thus constituting the color projection type video device. The green luminous component of this device is made of fluorescent material shown by the general formula LnOCl:xA (where Ln is one among La, Y, and Gd, and A and (x) are numbers satisfying 0.5- 10wt% to Tb and LnOCl respectively), and this fluorescent material is formed by sedimentation. The fluorescent material uses one of zinc silicate and aluminum silicate. Thus, the painting operation of the fluorescent screen is facilitated and the precision of the image on the screen 5 is improved.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention provides a projection type video device that magnifies images from three high-intensity cathode ray tubes that emit red, blue, and green light and projects them onto a large screen to reproduce a color image. and a method for manufacturing a green-emitting cathode ray tube used in the device.

[Technical background of the invention and its problems]

Currently, there is a projection-type video device on the market that uses three high-intensity cathode ray tubes that emit blue, green, and red light, and uses an optical lens to magnify the image and project it onto a large screen to reproduce a color image.

This video device has conventionally played TV images and has been widely used for educational and entertainment purposes, but in the future, the range of applications will expand as TV broadcasting and video systems become more sophisticated. It is expected. In order to make the brightness on the large screen as high as possible with this projection video device, it is necessary to apply approximately 10 times more electronic energy to the fluorescent surface of the queen cathode ray tube than with a normal direct-view color cathode ray tube. . For this reason, the temperature of the fluorescent surface rises to over 60"C during normal operation. It is generally known that the brightness of the fluorescent surface decreases as the temperature rises. Therefore, the projection type image device It is common knowledge that for commercial cathode ray tubes, different consideration is given to the structure of the fluorescent surface and the phosphors that make up the fluorescent surface than for direct-view color cathode ray tubes.

For example, a cathode ray tube is known which uses a structure that allows a layer of water to be retained on the outside of the phosphor surface of the cathode ray tube and uses means for suppressing the rise in temperature of the phosphor. It is also known to use a fan to blow air onto the outside of the fluorescent surface of a cathode ray tube for forced air cooling. However, these methods have the drawbacks of complicating the structure of the cathode ray tube and increasing manufacturing costs, so it is possible to produce efficient fluorescent lamps in operating conditions (without using special equipment as described above). It is required to use a light body.

By the way, the red phosphor, which is the phosphor that makes up one fluorescent surface, is made of yttrium oxysulfide, which is often used in direct-view color cathode ray tubes, and because the luminous efficiency decreases markedly due to temperature rise, it is made of europium. Activated yttrium oxide is used.

Furthermore, silver-activated zinc sulfide, which has high luminous efficiency, is used as the blue phosphor. Furthermore, the green phosphor is a zinc sulfide-based phosphor that is often used in direct-view color cathode ray tubes, and its luminous efficiency decreases significantly under high electron beam energy density. is used.

Now, when a white screen is regenerated on a projection screen, about 70% of its brightness is obtained from green, so of the red, blue, and green light emitting phosphors mentioned above, the luminous efficiency of the green light emitting phosphor is particularly improved. This results in a high-brightness projection-type video device. However, the manganese-activated zinc silicate conventionally used in this green-emitting phosphor has a low energy emission efficiency of about 7 times when stimulated with electron beams, and suffers from deterioration of the phosphor screen called burnout under high electron energy stimulation. There are drawbacks that can easily occur. Furthermore, terbium-activated gadolinium oxysulfide is preferable to the above-mentioned phosphors in terms of luminous efficiency of 10 or more, but it has the drawback that the efficiency decreases markedly due to temperature rise. Therefore, in the conventional projection image device, under normal operating conditions, only the same brightness can be obtained even if manganese-activated zinc silicate is used or terbium-activated gaddonium oxysulfide is used. Furthermore, due to the decrease in efficiency due to the temperature increase mentioned above, when using terbium-activated gadolinium oxysulfide, the color image becomes reddish due to the initial change over time within 10 minutes after starting projection of one image, and readjustment is necessary. This is extremely troublesome and tends to reduce the product value.

In addition to these reductions in luminous efficiency and efficiency due to temperature rise, the following conditions are required from the perspective of color image reproduction, which is the same as with direct-view color cathode ray tubes.

On the CIB chromaticity diagram, the colored light emitted by a green phosphor shows that the larger the value of X and the smaller the value of y, that is, the more yellowish the light, the more blue and green the white screen will be.

The sum of the electron beam energy applied to the red cathode ray tube becomes smaller, and the luminous efficiency of the entire imaging device increases. On the other hand, in order to widen the gamut of image reproduction, it is desirable to have the color as close to the edge of the chromaticity diagram (higher color saturation) as possible. From the above point of view, in a direct-view color cathode ray tube, the green component emission is usually 0.30 < x < 0.340.
57 < Selected to produce a chromaticity of Y. By the way, in the projection type, the luminous color of the green phosphor made of manganese-activated zinc silicate is X: 0.23 y = Q, 69, and the luminous efficiency of the entire imaging device when forming a white image has a strong green tinge. becomes lower.

Further, a phosphor made of terbium-activated gadolinium oxysulfide also has a drawback in that its emission color is x=0.3257=0.543, and its color saturation (purity) is low.

Furthermore, the manganese-activated zinc silicate phosphor has a long afterglow after the electron beam stimulation ends, and moving images tend to have tails, making them less practical.

In addition to the above-mentioned green phosphors, terbium-activated rare earth oxyhalide phosphors are known as phosphors that exhibit high efficiency when excited by electron beams. This phosphor was disclosed in an article published in 1967 in Philips Research Report, Volume 22, page 481.

This involves adding terbium as an activator to lanthanum oxybromide, lanthanum oxychloride, lanthanum oxyfluoride, yttrium oxyfluoride, yttrium oxychloride, and yttrium oxybromide to emit light by electron beam excitation. .

Based on the above considerations, the inventors applied lanthanum oxybromide from among the above to a color display projection type image device based on the consideration that it is advantageous as a substance that can emit light by electron beam excitation, but it was not possible to achieve the intended purpose. I could not do it. In other words, the luminescent color is x = 0.35 on the CIE chromaticity diagram,
y=0.57, and the color display in the above case becomes yellow, which is inappropriate for the green color required by the present invention. Furthermore, in the case of a projection type, if the fluorescent surface becomes overheated (approximately 80° C. or higher), the luminous efficiency will drop sharply. Furthermore, it has been found that the substance constituting the phosphor is chemically unstable, and the process of applying it to the phosphor surface tends to cause undesired flow, making it difficult to form a uniform film. .

In addition, among the above-mentioned fluorescent materials, especially lanthanum and gadolinium oxyhalide, Mr. J. G. Labatin took advantage of their high efficiency in X-ray and electron beam excitation and applied them to the fluorescent surface of an X-ray image converter. Tokuko (1977-1989) was issued to ensure that good results were obtained.
It is disclosed in No. 310. In particular, lanthanum oxybromide phosphors are said to have the highest luminous efficiency when excited by X-rays, and
It is said to be suitable for line intensifying screens. Furthermore, it has been disclosed that the bromide phosphor is effective in terms of luminous efficiency, high-temperature properties, etc. even in electronic excitation (American Electrochemical Society 1979).
Fall 2019 Extempuitive Abstract N13
06) Yes. It is also disclosed that good results were obtained when used in a black-and-white projection image device (emission color is white at low terbium concentration).

(American Electrochemical Society Spring 1981 Extemporan Abstract No. 153) However, as is clear from the above, it was found that the intended purpose could not be achieved in a color display projection image device using a lanthanum oxybromide phosphor. did.

Based on the above findings, the inventor of the present invention found that bromide phosphors cannot be used in color display projection video devices due to the above points, so he conducted further research and investigated rare earth oxyhalide phosphors. It has been found that a phosphor made of activated lanthanum oxybromide can be applied to a color projection image device.

Here, in order to construct a color projection type image device, it is necessary to fully satisfy the following severe conditions. In other words ■
Good color reproducibility of green from the perspective of color display (from the perspective of color composition with red and blue); ■No reduction in luminous efficiency at high temperatures (60°C or higher); ■High brightness characteristics. , ■ Little change over time, ■ High chemical stability, ■ Excellent manufacturability, and ■ Excellent afterglow properties.

[Purpose of the invention]

An object of the present invention is to provide a novel color projection type image device that satisfies the above-mentioned manufacturability and also improves brightness, and a method for manufacturing the same.

[Summary of the invention]

The color projection type image device of the present invention has the general formula LnOC1:T
b (However, Ln = La, Y, Gd) The surface of the phosphor is coated with silicates of zinc and aluminum, and water glass and barium nitrate in an appropriate ratio. using the sedimentation solution.

This method consists of forming a precipitated film of the phosphor on the inner surface of the face of the cathode ray tube. That is, lanthanum oxide (La2h
s), yttrium sources and oxygen sources such as yttrium oxide (Y20s), gadolinium sources and oxygen sources such as gadolinium oxide (Gd20+), terbicum sources such as terbium oxide (Tb20m) and Oxygen sources and ammonium chloride (NH, C
After weighing each predetermined amount of each chlorine source such as l) and thoroughly mixing them in a ball mill, the obtained mixed powder is placed in a quartz crucible, and an appropriate amount of carbon, for example, is placed therein. Bake at 1300°C for 30 minutes to 3 hours. When no carbon is added, the whole is fired in a reducing atmosphere (for example, nitrogen gas containing 2 to 5q6 hydrogen).

After the obtained fired product is cooled, it is placed in a nylon mesh bag, sieved with water, thoroughly washed with water, the surface of the phosphor is coated with, for example, zinc silicate, and after washing with water, it is filtered with, for example, alcohol. Then, after drying, the phosphor was passed through a 630 mesh through a stainless steel sieve, for example, and used as a phosphor film for a cathode ray tube. In addition, the Th concentration was set to 0.5
The reason why it is limited to the range of ~10% by weight is that if it is less than 0.5, the emitted light color becomes bluish, which not only causes a decrease in brightness, but also red,
It also results in a degradation of the white image in combination with blue-emitting cathode ray tubes. On the other hand, if it exceeds 10% by weight, the granularity of the phosphor changes, making it difficult to form a phosphor film by the sedimentation method, and causing the phosphor film to flow. The formation of the fluorescent film is based on the general formula LnOC1
l: 'rb (Ln = La - Y, Gd)
Water glass (K, 0.3SiO2
) and barium nitrate (Ba (NOs) t ) in an appropriate ratio. That is, as shown in FIG. 1, a green-emitting fluorescent film (3) is formed on the inner surface of the face (2) of a cathode ray tube (1) by a sedimentation method.

Next, using europium-activated yttrium oxide (Y, 03: Eu ) as a red-emitting phosphor, a red-emitting phosphor film (3 ) to form.

Furthermore, silver-activated zinc sulfide (ZnS:
A blue light-emitting film (3) is formed using Ag) in the same way as the red light-emitting fluorescent film.

The thus formed cathode ray tubes IJIG and IB having fluorescent films that emit green, red and blue light are arranged in parallel as shown in FIG. 4B is attached to adjust the light according to each luminescent color emitted from each fluorescent surface, and the light is focused on a screen (5) attached at a predetermined interval to produce a color projection type. The video device is configured.

〔Effect of the invention〕

An operating voltage of approximately 28 KV is applied to the anodes of each of the cathode ray tubes IR, IG, and IB, thereby causing electron beams to impinge on the fluorescent surfaces to emit light. In this case, even when the high electron beam characteristic of the projection type was bombarded, the phosphor film (3) emitting the recorded color rose to about 80 degrees Celsius, but there was almost no deterioration and the luminance remained the same as before. The efficiency was improved by about 10 times compared to (the phosphor without zinc silicate coating), and there was also almost no decrease in efficiency. In addition, there is almost no deterioration of the red-emitting phosphor film and the blue-emitting phosphor film, and the phosphor film is red.

Since it is possible to approximate the emission brightness of each color of green and blue, and there is almost no change over time, the color reproducibility is comparable to that of a conventional green-emitting cathode ray tube using a phosphor without zinc silicate coating. degrees (x = 0.329
, y = 0.589) is the same name (x = 0.589).
332, Y = o,! ')s! 5), and has the characteristic that color reproducibility can be greatly expanded.

Red-emitting phosphor is Y, O, :Eu, blue-emitting phosphor is Z
n8: Each light emitting cathode ray tube is formed using Ag. The green-emitting phosphors are Examples 1 to 4 in Table 1 above.
As shown in La20. , Y, 0. ,Gd,O,,NH
, CIl.

Tb, 0. Weigh each of the raw materials and mix them well. This mixture is placed in a quartz crucible, an appropriate amount of carbon is placed on top, the lid is closed, and the crucible is fired at 1200°C for 2 hours.

When carbon is not added, it is fired in a reducing atmosphere.

Place the fired product in a nylon mesh bag, rinse thoroughly with water, filter, and weigh the phosphor.

After that, add 500 g of pure water to 100 g of phosphor weight.
Add 1 ml of ZnSO4.
Stir for a minute.

After washing with pure water, it is filtered with ethanol to complete the coating with zinc silicate. This zinc silicate phosphor is
The green-emitting phosphors of Examples 1 to 4 in Table 1 are prepared and used.

Next, a phosphor suspension was prepared by preparing an aqueous solution of 1.0 g of the phosphor emitting the above recording color in pure water and water glass with a concentration of 25% to a total volume of 200 ml. This was transferred to a Finch cathode ray tube with a total of 400 barium nitrate solution and pure water at a concentration of 2.
Add to ml and let stand.

The above suspension was poured into this and left to stand for 30 minutes. After the phosphor settles to form a film, the supernatant liquid is poured off to obtain a phosphor surface. The amount of water glass with a concentration of 25% added in Examples 1 to 4 was 30 m/the amount of barium nitrate with a -2% concentration was 20 m1. This green-emitting phosphor coated with zinc silicate has better dispersibility in the sediment than the conventional phosphor without zinc silicate coating, which has the same composition formula, and has the same particle size. If so, a cleaner fluorescent film could be obtained. This probably led to the establishment of reproducibility of green-emitting cathode ray tube brightness and improved brightness.

An organic film was formed on the resulting fluorescent surface by lacquer filming, and an aluminum film was then vapor-deposited on top of it. After painting, an electron gun was attached to complete the cathode ray tube. 28 KV.

Table 1 shows the relative values of 1 cathode ray tube brightness at 1200/jA, 130 x 100 mm' raster size.

The brightness obtained when the cathode ray tube of Example 3 is caused to emit light at room temperature at an accelerating voltage of 28 KV is expressed as a function of the applied current, and is shown as a curve a in FIG. Even when the electron beam current is 600 IiA or more, the luminance increases in proportion to the electron beam current,
It is clear that the present invention is extremely suitable for use in a color projection type image device. For comparison, the light emission characteristic curve of a cathode ray tube whose phosphor film is a conventional phosphor without zinc silicate coating is shown.

FIG. 4 shows the relationship between the emission brightness and the temperature rise on the face of the green, blue, and red light-emitting cathode ray tubes, where the first curve A is green and the second curve is blue.

C represents the relative brightness of each red luminescent color. As is clear from this brightness characteristic, the green light emitting phosphor is almost aligned with the center, and the temperature rise on the face surface is 70%.
Extremely stable brightness can be obtained even at temperatures above ℃. This is advantageous in adjusting the accelerating voltage applied to each cathode ray tube. The luminance of the green-emitting cathode ray tube with respect to rising humidity was good, as shown by curve A in FIG. 4, regardless of the presence or absence of the zinc silicate coating. Furthermore, since the relative brightness is the same as above, even if the phosphor surface increases during operation, there will be very little change in the color of each emitted light emitted from each cathode ray tube, so stable color images will be maintained over time. There are characteristics that can be obtained without any physical change.

Note that since the luminance of each of the above-mentioned phosphors is relatively uniform, even if the respective acceleration voltages are lowered to some extent, the luminance color hardly changes and the luminance decreases only slightly. In this way, stability can be improved and the speed at which the electron beam impinges on the fluorescent film can be reduced, so that the life can be extended by that amount.

In addition to the red light-emitting phosphor described above, the following can be used. Ca8: Eu, YVO,: Eu
, La0C1:Eu Furthermore, the following blue-emitting phosphors can also be used. Ca8: Bl-8rSa (
hp8. :Ce, La0CA: Tm Table 2 28 shows 'v12ooμA (raster size 1
Our catalog 111k with input conditions of 3x1.0CR)
The brightness of a green-emitting cathode ray tube obtained when an lE2884 Nofinch cathode ray tube is operated for 60 minutes is shown in comparison with two comparative examples. Comparative Example 1 is a cathode ray tube with a terbium-activated gadolinium oxysulfide phosphor.

Comparative Example 2 is a conventional terbium-activated lanthanum oxychloride phosphor cathode ray tube without a zinc silicate coating.

Table 2 (Footlambert) As is clear from this table, the brightness of the green-emitting cathode ray tube used in the device of the present invention is 198 times brighter than that of Comparative Example 1, and 111 times brighter than that of the cathode ray tube without zinc-silicate coating. I love bright things.

On the chromaticity diagram in Figure 5, the luminous chromaticity point of the cathode ray tube of Example 3 when measured under the conditions of 28 KV and 1200 μA is marked G.

(x = 0.3327 = 0.585)
. For comparison, G, + niterbium-activated gadolinium oxysulfide (x = Q, 325.

y = 0.543), chromaticity point of manganese-activated zinc silicate on Ga (x = 0.212, y = 0.
701). From this figure, it can be seen that 01 is close to the green area of a direct-view color cathode ray tube and is advantageous for producing a white screen, and has a wider color re-viewing range than Gt.

When this cathode ray tube was installed in a projection video device and the visibility was evaluated, the focus on the projection screen was good, and the color image was brighter than the conventional one without zinc silicate coating, proving its beautiful green color. In addition, there was little deterioration of the green light emitting component due to fading of the cathode ray tube or temperature rise, so color images did not change over time. In addition, the reproduction of cathode ray tube brightness is also good and manufacturability has become easier.

[Brief explanation of the drawing]

The figures are for explaining the color projection type image device of the present invention, and FIG. 1 is a side view of a cathode ray tube, FIG. 2 is a schematic diagram of the device, FIGS. 3 and 4 are characteristic diagrams, and FIG. 5 is a light emission diagram. It is a CIE chromaticity characteristic diagram showing a chromaticity region. Representative Patent Attorney Kensuke Chika (and 1 other person) No. 1
Figure 2 Figure 8 Figure 4 Brown layer Noboru Kayama Figure 5

Claims (1)

[Claims] (1) In a color projection video device consisting of a set of three cathode ray tubes with three primary color luminescent screens, the green luminescent component is expressed by the general formula LnOC/:xA (where Ln is La, Y
and at least one of the mountains A represents Tb and X represents a number satisfying a weight ratio of 0.5 to 10 with respect to LnOCl. A color projection type image device characterized in that it is coated with 11N of at least one of zinc silicate, aluminum silicate, and nium silicate. (2. A color projection type image device according to claim 1, characterized in that the phosphor is formed by a sedimentation method.