JP2601857B2 - Projection type color television equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a projection type color television apparatus,
In particular, the present invention relates to a projection type color television apparatus for increasing the brightness of a projected image on a screen.

(Prior Art) A projection type color television apparatus for displaying a color image on a screen is provided with a single-color cathode ray tube having a phosphor screen that emits red, green, and blue light, and a plurality of cathode ray tubes are provided on a front portion of each of the cathode ray tubes. An optical lens having a combination of two lenses is arranged, and the image obtained on the phosphor screen is enlarged and projected on a screen.

This projection type color television device is used for displaying video images, video signals, personal computer signals, computer graphics, etc., and it is required to increase the brightness of images on large screens. ing.

In order to increase the brightness of the image on the screen, it is necessary to apply electron beam energy 10 times or more to the phosphor screen as compared with a normal direct-view type color cathode ray tube. In response to such demands, phosphors generally used in direct-view color cathode ray tubes have a so-called luminance saturation in which light emission characteristics deteriorate as electron beam energy increases in a low current range. Is not suitable.

In particular, when a white screen is reproduced on a screen, about 70% of the luminance is occupied by green luminance. Therefore, in a projection type color television apparatus, a green phosphor having high luminous efficiency and high luminance saturation is used. This is very important.

As a green phosphor that satisfies the luminous efficiency and luminance saturation of the cathode ray tube in the above-mentioned projection type color television apparatus, a rare earth phosphor activated with a teletemium, that is, a lanthanum oxychloride phosphor (LaOCl: Tb) with a teletemium or a teletemium is attached. Active yttrium silicate oxide phosphor (Y ₂ SiO ₅ : Tb) and the like. In particular, JP-A-59-93784
The publication discloses that LaOCl: Tb phosphor is effective as a green phosphor having high luminous efficiency.

(Problems to be Solved by the Invention) As described above, there are LaOCl: Tb phosphor and Y ₂ SiO ₅ : Tb phosphor as green phosphors suitable for increasing the brightness of an image of a projection type color television apparatus. Is known. However, recent projection type color television apparatuses tend to greatly increase a peak current for forming an image on a phosphor screen of a cathode ray tube in order to increase the brightness of an image on a screen. On the other hand, the LaOCl: Tb phosphor has a luminance saturation characteristic in a high current region where the anode current is 2 to 3 mA or more, which is Y ₂ SiO _2.
5 : Inferior to Tb phosphor. On the other hand, Y ₂ Si
O ₅ : Tb phosphor has excellent luminance saturation characteristics from low current region to high current region, but the luminous efficiency in low current region is LaOCl: Tb
There is a problem that it is lower than the phosphor.

That is, as a green phosphor of a cathode ray tube of a projection type color television device, it is required that the emission luminance is high from a low current region to a high current region, and that the luminance saturation in the high current region is excellent. Conventional phosphors, even those with excellent emission luminance and luminance saturation characteristics, have luminance saturation in high current range,
Alternatively, there is a problem in light emission luminance in a low current region.

The present invention has been made in view of the above problems, and a cathode ray tube having a phosphor screen having high emission luminance over all current ranges from a low current range to a high current range and having excellent luminance saturation in a high current range. And a projection type color television apparatus comprising:

[Constitution of the Invention] (Means for Solving the Problems) A projection type color television apparatus for enlarging an image on a fluorescent screen of each monochromatic cathode ray tube emitting red, green and blue light with an optical lens and projecting the image on a screen. In, the phosphor screen of the cathode ray tube emitting green light was changed to LaOCl: Tb phosphor and Y ₂ SiO ₅ : T
b composed of a mixed phosphor mixed in a weight ratio of 1/1 to 1/4, preferably, titanium oxide (TiO ₂ ) is added to LaOCl: Tb phosphor, and preferably, LaOCl: The average particle size of the Tb phosphor is 10 to 13 μm, and the average particle size of the Y ₂ SiO ₅ : Tb phosphor is 4
６6 μm.

(Function) As described above, the fluorescent screen of the cathode ray tube emitting green light is
l: Tb phosphor and Y ₂ SiO ₅ : When composed by mixing Tb phosphor, the emission luminance is high over the entire current range from the low current region to the high current region, taking advantage of the characteristics of each single phosphor, In addition, a cathode ray tube having a phosphor screen with excellent luminance saturation in a high current region can be obtained.

Hereinafter, the present invention will be described based on embodiments with reference to the drawings.

Since the configuration of the projection type color television apparatus has been described above, a description thereof will be omitted, and the phosphor screen made of a green phosphor of a cathode ray tube used in the apparatus will be described below.

The phosphor screen of the cathode ray tube in this example is composed of LaOCl: Tb phosphor and Y ₂ Si
It is composed of a mixed phosphor with an O ₅ : Tb phosphor, and the mixing ratio thereof can be in the range of LaOCl: Tb / Y ₂ SiO ₅ : Tb = 1/1 to 1/4 by weight. Also, preferably, LaOCl: Tb phosphor
TiO ₂ added, more preferably, average particle size 10-13μm
LaOCl: Tb phosphor and Y ₂ SiO ₅ : Tb having an average particle size of 4 to 6 μm
It is composed of a phosphor mixed with a phosphor.

Table 1 shows the mixed phosphors, in particular, a mixed phosphor of a TiO ₂ added LaOCl: Tb phosphor and a Y ₂ SiO ₅ : Tb phosphor, and LaOCl: Tb.
The luminance characteristics of the phosphor screen formed using a mixed phosphor obtained by mixing a small-diameter Y ₂ SiO ₅ : Tb phosphor with respect to the phosphor, LaOCl: Tb
The phosphor and the Y ₂ SiO ₅ : Tb phosphor were used alone and
iO ₂ added LaOCl: in comparison with that of the fluorescent surface formed by Tb phosphor only.

Each of the phosphor screens shown in Table 1 is a 390 cc pure water, 2% by weight pure water for a cathode ray tube for a 7-inch projection type color television.
10cc of barium nitrate solution, 400cc in total, and add pure water
A liquid in which a predetermined amount of a phosphor is suspended in a water glass solution of a total of 200 cc, a water glass solution of 180 cc and 25% by weight and a total of 200 cc, is left to stand for about 30 minutes, and the supernatant is settled after the phosphor has settled. It was formed by pouring out and drying at room temperature. This phosphor screen was used to measure brightness, after which an organic film was formed thereon by filming treatment, and an aluminum film was further deposited thereon to form a metal back phosphor screen, and after baking, the electron gun was used. It was sealed, evacuated and sealed in a cathode ray tube.

Then, the luminance measurement was performed with a raster size of 122 × 91 mm, an anode voltage of 29 KV, and an anode current of 200 μA, 1600 μA, and 3500 μm.
A.

As can be seen from Table 1, the LaOCl: Tb phosphor and Y ₂ Si
The phosphor screen composed of a mixed phosphor with O ₃ : Tb phosphor is all LaO
Compared with a phosphor screen composed of a Cl: Tb phosphor or a Y ₂ SiO ₅ : Tb phosphor alone, a higher emission luminance is obtained in each current region.
When TiO is added to the LaOCl: Tb phosphor, T
iO ₂ without addition of LaOCl: emission brightness than the phosphor screen consisting of Tb phosphor is increased, in particular TiO ₂ added LaOCl: Tb phosphor and its
The phosphor screen formed of the mixed phosphor obtained by mixing the LaOCl: Tb phosphor with the Y ₂ SiO ₅ : Tb phosphor having a small diameter exhibited the highest emission luminance in each current region.

In particular, FIG. 1 shows a phosphor screen composed of a TiO ₂ -added LaOCl: Tb phosphor shown in Table 1 and a mixed phosphor obtained by mixing the LaOCl: Tb phosphor with a small-diameter Y ₂ SiO ₅ : Tb phosphor. The luminance characteristics from low current range to high current range of LaOCl: Tb phosphor and Y ₂ Si
The results are shown in comparison with those of a phosphor screen composed of O ₅ : Tb phosphor alone. Curve (1) shows the luminance characteristics of the phosphor screen made of the mixed phosphor, and curves (2) and (3) show those of the phosphor screen consisting of the LaOCl: Tb phosphor and the Y ₂ SiO ₅ : Tb phosphor alone.

As can be seen from this figure, the phosphor screen composed of the mixed phosphor of this example of the curve (1) is different from the phosphor screen composed of the component phosphor alone of the curves (2) and (3) in the low current region and the high current region. In other words, to improve the low emission luminance of the Y ₂ SiO ₅ : Tb phosphor in the low current region, and to improve the luminance saturation characteristics of the LaOCl: Tb phosphor in the high current region, High emission brightness in low current range and excellent saturation in high current range, high emission brightness in all current ranges from low current range to high current range, and excellent brightness saturation in high current range Has become a phosphor screen.

The LaOCl: Tb phosphor used for the phosphor screen of the cathode ray tube of the projection type color television set includes 10 to 13
An average particle diameter of 4 μm is required for the Y ₂ SiO ₅ : Tb phosphor mixed with the LaOCl: Tb phosphor.
Is good. As an example, FIG. 2 shows that the average particle diameter of the LaOCl: Tb phosphor is 11 μm, which is 2 μm to 12 μm.
₅ shows a change in emission luminance when an equal amount of μm Y ₂ SiO ₅ : Tb phosphor is mixed.

[Effects of the Invention] When the phosphor screen of the cathode ray tube of the projection type color television apparatus that emits green light is composed of a phosphor mixture of LaOCl: Tb phosphor and Y ₂ SiO ₅ : Tb phosphor, the phosphor of each single phosphor is By taking advantage of the features, a cathode ray tube having a fluorescent screen having high emission luminance over all current ranges from a low current range to a high current range and having excellent luminance saturation in a high current range can be obtained. Therefore,
By using such a cathode ray tube, it is possible to display a bright image on the screen without raising the anode voltage more than necessary, causing unwanted discharge in the tube, or increasing the current to deteriorate the phosphor screen or cathode. Projection type color television apparatus.

[Brief description of the drawings]

FIG. 1 shows a phosphor composed of a TiO ₂ -doped LaOCl: Tb phosphor according to one embodiment of the present invention and a mixed phosphor obtained by mixing the LaOCl: Tb phosphor with a small-diameter Y ₂ SiO ₅ : Tb phosphor. FIG. 2 is a diagram showing the luminance characteristics of the surface in comparison with those of the phosphor screen composed of the LaOCl: Tb phosphor and the Y ₂ SiO ₅ : Tb phosphor alone. FIG. 2 shows Y ₂ SiO ₅ mixed with the LaOCl: Tb phosphor. FIG. 4 is a diagram illustrating a relationship between the particle size of a Tb phosphor and emission luminance.

Claims (3)

(57) [Claims] 1. A projection type color television for displaying an image on a phosphor screen of each of the monochromatic cathode ray tubes emitting red, green and blue light, enlarging the image on the phosphor screen by an optical lens, and projecting the image on a screen. in the device, a phosphor screen of a cathode ray tube which emits the green LaOCl: Tb phosphor and Y ₂ SiO _5: Tb and a phosphor in a weight ratio of 1 / 1-1 / 4 to consist of mixed mixed phosphor A projection type color television device characterized by the above-mentioned. 2. The projection type color television device according to claim 1, wherein TiO ₂ is added to the LaOCl: Tb phosphor. 3. The LaOCl: Tb phosphor has an average particle size of 10 to 13 μm, and the Y ₂ SiO ₅ : Tb phosphor has an average particle size of 4 to 6 μm. 2. The projection type color television apparatus according to 2.