JPS6011580A - Green color cathode ray tube and its use for projection type image forming device - Google Patents

Abstract

PURPOSE:To provide a cathode ray tube which phosphoresces in green color with an improved efficiency of phosphorescence without causing the lowering of luminance due to an increase in surface temp., by forming a phosphorescent surface by use of a specified terbium-activated lanthanum oxychloride phosphor. CONSTITUTION:A phosphorescent surface for a projection type green color cathode ray tube is formed by use of a terbium-activated lanthanum oxychloride phosphor having a terbium concn. of 0.5-10/LaOCl wt%. The cathode ray tube shows minimized lowering of luminance due to the temp. rise on the surface and has a construction as shown by the figure, with the phosphorescent surface kept at an angle of 60 deg.C. The phosphorescent surface is formed by combined use of blue and red color phosphors having the same levels of emission efficiency as luminance of the cathode ray tube at a temp. of the face in operation. A silver-activated zinc sulfide phosphor is used for blue color and a europium- activated yttrium phosphor, for red color. These colors have well-balanced luminance and cause little aberration of color image even when the temp. rises.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a projection system that reproduces a color image by enlarging the images of three high f4 degree cathode ray tubes emitting red, blue, and green light and projecting them onto one large screen. The green-emitting cathode ray tube C2 is used in a type of image display device C2.

[Technical background of the invention and its problems] Generally, this type of video device reproduces television images and is widely used for education and entertainment, but in the future, high-definition screens ( It is expected that the range of applications will expand as a result. In order to maximize the brightness on the large screen, this projection type image device applies more than 10 times more electron beam energy than the fluorescent surface C of the cathode ray tube (-) of a normal direct-view color cathode ray tube.For this reason, The temperature of the fluorescent surface is high during normal operation, up to about 150℃ (it rises to 150℃).
2 The brightness of the fluorescent surface decreases as the temperature increases.

(2) When a white screen is reproduced on a projection screen, approximately 70% of its brightness is obtained from green. The green-emitting cathode ray tube used in the conventional projection type image device C2 uses a manganese-activated zinc silicate phosphor or a terbium-activated gadolinium oxysulfide phosphor as a phosphor. The former type of phosphor has a low energy emission efficiency when stimulated with an electron beam, and has the disadvantage that under high electron energy stimulation, it tends to cause deterioration in the phosphorescence called burnout. Furthermore, although the latter has a relatively high efficiency of emitting energy under electron beam stimulation, it has the disadvantage of a significant drop in efficiency due to temperature rise. For this reason, a method was used to cool the front surface of the cathode ray tube by forcibly blowing air from the fan C. There were drawbacks such as a reddish tint that required readjustment.

In addition to the above-mentioned green phosphor, a terbium-activated rare earth oxyhalide phosphor is known as a phosphor that exhibits high efficiency upon C''-electron beam excitation. Philips Research Report Volume 22 481
Disclosed by the paper on page.

The contents are lanthanum oxybromide, lanthanum oxychloride, lanthanum oxyfluoride, yttrium oxyfluoride, yttrium oxychloride, and yttrium oxybromide C: Terbium is added as an activator and emitted by electron beam excitation. be.

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. That is, in the case of a projection type, when the fluorescent surface of the C2 becomes overheated (approximately 80° C. or higher), the luminous efficiency decreases rapidly. Furthermore, the substance constituting the above-mentioned phosphor is chemically unstable, and in the process of applying it to the phosphor surface C2, an undesirable flow occurs, making it difficult to form a uniform film and easily becoming abrasive. There was found.

Yttrium oxychloride, which is said to have high brightness and high efficiency, is chemically unstable and difficult to form a fluorescent surface, making it impractical. It has been confirmed that a reaction occurs with the sintering container, resulting in a decrease in C2 purity and inability to perform sintering, making it impractical.

[Object of the Invention] The present invention has been made in view of the above-mentioned drawback C.It is an object of the present invention to provide a CRT for a projection type image device that emits green light and is free from a decrease in brightness due to face temperature rise [2] and has improved luminous efficiency. It is something to do.

[Summary of the Invention] In order to achieve the above object, a projection type cathode ray tube that emits C-green light is provided with a phosphor S-terbium concentration of 0.5 to lo
This is accomplished by forming a fluorescent surface using a terbium-activated lanthanum oxychloride phosphor in the range f2/La0cj wt%.

[Effects of the Invention] According to the present invention [2], when the outer surface of the face of a green-emitting projection cathode ray tube rises to about 150 degrees Celsius, the luminance is 60 degrees higher than that of the outer surface of the face of a conventional green-emitting phosphor. The luminance is more efficient than the luminance when the temperature rises to 0.degree. C., and luminance characteristics with high luminous efficiency can be obtained over an extremely wide range of temperatures. This increases the degree of freedom in selecting the phosphor used in the other two red and blue-emitting cathode ray tubes (:, the cooling means for the outer surface of the cathode ray tube face is extremely simplified by increasing the luminous efficiency of the green component. It has the effect of being able to.

[Embodiments of the Invention] Examples of the present invention will be described in detail below with reference to the drawings.

The inner surface C2 of the projection type cathode ray tube of the present invention is a fluorescent surface of a terbium-activated lanthanum oxychloride phosphor formed by the following method.

That is, the present inventors investigated the concentration of water glass and barium nitrate in the sedimentation solution using the precipitation method C: the process of forming a fluorescent surface in a water glass aqueous solution conventionally used in industrial or black-and-white cathode ray tubes. Ratio (WG/Ba) is 20-3
5, it was found that a C-2 fluorescent surface was easily formed.

In addition, the present inventors have found that even if a cathode ray tube is formed by forming a phosphor surface by a precipitation method and then forming a cathode ray tube through the usual lacquer filming, aluminum film forming process, and paking process, the deterioration of the phosphor is small. I found it. First, for the phosphor, 100 g of lanthanum oxide, 58 g of ammonium chloride, and 14 g of terbium oxide were weighed and mixed well. This mixture is placed in a quartz crucible, topped with an appropriate amount of carbon, covered with a lid, and fired at 1200°C for 2 hours. If no carbon is placed, fired in a reducing atmosphere. Store the fired product in a nylon mesh bag. - Pour into a sieve of water, rinse thoroughly with water, soak with alcohol and dry to make a terbium-activated lanthanum oxychloride phosphor and use it.

Next, a phosphor suspension was prepared by adding 1.0 g of the above green-emitting phosphor to 200 m/l of a mixture of pure water and 25% water glass. On the other hand, add a total of 400 g of barium nitrate solution with a concentration of 2 and pure water to a Finch cathode ray tube and leave it to stand. Pour the above suspension into the tube and let it stand for 30 minutes. Fluorescence After the bodies settle and form a film, the supernatant liquid is poured off to obtain a fluorescent surface.

An organic film was formed on the resulting phosphor surface by Nirakker Filming C2, and then a NiAluminum film was deposited on it, and after painting, an electron gun was attached to complete a cathode ray tube. FIG. 1 shows a comparison of the luminance of the fluorescent material of the present invention and the conventional fluorescent material C28KV when the fluorescent material emits light at room temperature with an applied voltage of 28 KV. The curve (a) in FIG. 1 shows the luminance of the cathode ray tube of the present invention.
b) shows the luminance of the conventional cathode ray tube [2] As is clear from this figure, the cathode ray tube of the present invention is brighter than the conventional cathode ray tube.

In normal operation, the outer surface of the face of C-projection CRTs has a certain temperature, and this temperature is not necessarily the same depending on the model used, and the temperature range varies from 40℃ to 150℃.Direct-view CRT C: Comparison The range of variation is wide and high. Therefore, the present inventors have developed a cathode ray tube (
In addition, for cathode ray tubes with different terbium concentrations while heating the cathode ray tube face temperature to 200° C. at 28 KV and 900 μA, the relationship between the change in terbium concentration i2 and the brightness is shown in Fig. 2 for each heating temperature.

The face is heated with a heater and eaten. Curve (1) is 25℃,
Curve (2) is 60℃, curve (81 is 100℃, curve (4)
) is a relative brightness characteristic curve with respect to terbium concentration when the face surface is heated to 150°C and curve (6) is heated to 200°C. Here, the relative brightness is a comparison with the brightness of a conventional cathode ray tube using a terbium-activated gadolinium oxysulfide phosphor at 28 KV, 900 μm, and a face temperature of 60° C. as 100. Further I
: There are two cathode ray tubes C of the present invention, which use a conventional terbium-activated gadolinium oxysulfide phosphor, and the C2 is adjusted so that the brightness of both C2 is almost the same when the face surface of each is around θ°C. Set the brightness to 100 and set the face surface to 2.
Figure 3 shows the change in luminance of each sample when heated to around 00°C. Curve (a) shows the cathode ray tube of the present invention, and curve (b) shows the characteristics of the conventional cathode ray tube.

According to Figure 2, the terbium concentration is 0.5 to 10/La0.
It can be seen that within the range of cj weight %, light is emitted with extremely high efficiency even when the face temperature rises to about 150°C. Furthermore, it can be seen that if the niterbicum concentration is narrowed down to a range of 3 to 8/La0c2% by weight, the brightness will be sufficient for practical use even if the face surface rises to about 200°C. Also, according to FIGS. 2 and 3, the green-emitting cathode ray tube of the present invention has 6
The light emission peaks at a face temperature of around 0°C, which is a new characteristic not found in conventional cathode ray tubes.

Therefore, the present inventors adopted the cathode ray tube of the present invention, which exhibits less reduction in brightness as the temperature rises on the face surface, and adopted a cathode ray tube structure that maintains the face surface at 60° C. in FIG. This is the structure of the Catalog N0B28840 Finch cathode ray tube product listed in our product catalog. Then, blue and red phosphors having luminous efficiency equivalent to the brightness of the cathode ray tube of the present invention are selected with respect to the surface temperature C2 created by this face surface during operation, and the fluorescent surface of the cathode ray tube is changed. Formed. The temperature characteristics of a cathode ray tube ((a
); green, (b); blue, (C); red) Figure 5 C: Shown. As is clear from this figure, the brightness of these three colors is well balanced, and it can be seen that there is little color shift in the color image even when the temperature rises.

In the cathode ray tube shown in Fig. 4, 41 is the tube body, and on the inside of the outer face 42 of the tube body 41, there is a color of green, tone, or red that is emitted by an electron beam from an electron gun (not shown). A phosphor surface 43 that emits light is formed. A front glass 45 is provided on the outside of the face outer surface 42 with a metal mesh plate 44 interposed therebetween, and a metal support is provided around the C2 front glass 45 and the tube 41 so that the plate 44 is in close contact with the face outer surface 42. The front surface of the lath 45 and the plate 44 are fixed to the tube body 41 by a presser metal fitting 46 which also serves as a tool.

The plate 44 receives the heat generated on the outer surface 42 of the face and transfers it to the holding metal fitting 46 (Y) by conduction.
It has the function of emitting two.

According to this 1W cathode ray tube, cooling is achieved with a single component structure of the cathode ray tube, and its structure is extremely reliable without requiring a fan for cooling as in the past. 1 single C'i:ru.

Table 1 g-28KV900μ people (raster size 13
×10-) Input conditions of our catalog No. F, 28
When operated for 60 minutes on an 84 Finch cathode ray tube.
2. The brightness of the obtained cathode ray tube emitting green light is compared with that of conventional example 2. Conventional Example 1 is a cathode ray tube made of terbium-activated gadolinium oxysulfide, and Conventional Example 2 is a cathode ray tube having a structure in which the fluorescent surface of the cathode ray tube of Conventional Example 1 is forcibly cooled by a fan.

Table 1 From this table, the brightness of the green-emitting cathode ray tube included in the device of the present invention after 60 minutes is 59.5% brighter than the conventional example 1 in which the cathode ray tube is not cooled, and 41.2 inches brighter than the conventional example 2. I understand.

The emission chromaticity point of a cathode ray tube at C2 28 KV and 1200 μAI on the chromaticity diagram in Figure 6 is shown in (a) (x =
0.329.

7=0.589). For comparison (b) I uterbium activated gadolinium oxysulfide (X = 0.339, y =
0.560 ), (c) Color point of I-nimanganese activated zinc silicate (X=0.212.

7=0.701). From this figure, it can be seen that (a) is advantageous in producing a near-white screen in the green region of a direct-view color cathode ray tube, and has a wide brown color reproduction range.

When the visual perception was evaluated using a projection video device, it was found that the focus on the projection screen was good, the color image was brighter than before, and the advantage of beautiful green color was demonstrated. Further, since there was little decrease in the green light emitting component due to burnout of the cathode ray tube or temperature rise C2, no change in color images occurred over time.

[Brief explanation of the drawing]

The drawings provide a detailed explanation of the present invention, in which Figure 1 is a characteristic diagram showing the brightness and stimulation of the green-emitting cathode ray tube of the present invention, and Figure 2 is a characteristic diagram showing the brightness and stimulation of the green-emitting cathode ray tube of the present invention. FIG. 3 is a characteristic diagram showing the relationship between the brightness of the lanthanum oxychloride phosphor and the terbium concentration; FIG. The figure is a partially cutaway perspective view showing a specific example of the green-emitting cathode ray tube of the present invention, and FIG. FIG. 6 is a CIE chromaticity characteristic diagram showing the emission chromaticity region of a projection type image device using the green-emitting cathode ray tube of the present invention. 41...Tube body 42...Face outer surface 43
...Fluorescent surface 44...Gold mesh plate 45...
Front glass 46... Presser metal agent Patent attorney Noriyuki Chika (and 1 other person) No. 1 Fig. 2 Fig. 3 Brows゛Manufacturer 1 [Izumi Fig. 4 a Otsu 5 Fig. 6 Figure ρl-f e-t a3 ao tysρ67270.
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Claims (1)

[Claims] (1) Terbium concentration is 0.5 to 10/La0cJ
A green-emitting cathode ray tube characterized in that a fluorescent surface is formed of a terbium-activated lanthanum oxychloride phosphor having an M t % in the range C2. (2) The above terbium concentration is 3 to 8/La0c2% by weight
A green-emitting cathode ray tube according to claim 1, characterized in that the green light emitting cathode ray tube has a range of . (8) Terbium concentration is 0.5-10/Laoc
a green-emitting cathode ray tube having a fluorescent surface formed with a terbium-activated lanthanum oxychloride phosphor in the range of j% by weight;
A blue-emitting cathode ray tube with a fluorescent surface made of a silver-activated zinc sulfide phosphor, a red-emitting cathode ray tube with a fluorescent surface made of a europium-activated yttrium oxide phosphor, and each of these tubes that emit green, blue, and red light. 1. A projection-type video device characterized by comprising: a power r1) for enlarging an image of a cathode ray tube and projecting it onto a screen.