JPS6041640Y2 - Color image projection device - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a color image projection device that uses a cathode ray tube and is capable of producing a color image on a screen larger than the reproduction screen of the cathode ray tube.

Conventionally, this type of color image projection device uses a single color cathode ray tube 1 capable of obtaining a normal color reproduction image, as shown in FIG. 1, and reflects the reproduced color reproduction image 2 on its phosphor screen. Although not shown, a mirror 3 and a projection lens system 4 are configured to project onto a projection screen.

However, a color image projection device having such a single-tube configuration has a drawback in that a sufficiently bright projected image cannot be obtained.

In addition, as another color image projection device, as shown in FIG.
Three monochrome cathode ray tubes IR, IG and I, each reproducing
The red, green, and blue images 2R, 2G, and 2B from each cathode ray tube IR, IG, and IB are projected using the projection lens system 4R.
, 4G and 4B, and are superimposed on each other on a projection screen (not shown), thus obtaining a color projected image in which images of each color are projected.

In principle, a color image projection device with such a three-tube structure can obtain a projected image several times brighter than the color image projection device with a single-tube structure explained in Fig. 1. However, on the other hand, the disadvantage is that the device becomes significantly larger and more expensive.

The present invention provides a color image projection system that can provide a brighter projected image than the single-tube color image projection device described above, and can be configured to be smaller and cheaper than the three-tube color image projection device. It provides equipment.

That is, in the present invention, a two-tube structure is adopted, consisting of a first cathode ray tube that produces a monochromatic reproduced image and a second cathode ray tube that produces a reproduced image in which the other two colors are threatened. However, in particular, the present invention aims to improve the image quality of the projected image in a video projection device with this two-tube configuration, so that a brighter image can be obtained.

That is, in the present invention, we focused on the fact that when it comes to human visibility when it comes to blue and green, even if the blue has a slight edge or the green has a slight edge, it is not noticeable, and the red image is A two-color image of blue and green is obtained as a particularly bright image by a second color cathode ray tube.

An example of the present invention will be explained with reference to FIG. 3. In the figure,
Reference numeral 5 indicates the color image projection apparatus according to the present invention as a whole, and reference numeral 6 indicates its housing.

In the present invention, among the color images to be reproduced, the first cathode ray tube IR is monochromatic red, which reproduces only the red component image 2R, and the second cathode ray tube IR reproduces only the red component image 2R of the color image to be reproduced. A second cathode ray tube IBG that reproduces an image 28G in primary colors is provided, and a gicroic mirror 7 reflects, for example, a red reproduced image 2R obtained by the first cathode ray tube 1R, and the second cathode ray tube IBG By transmitting the obtained blue and green reproduced images 28G, both images 2R and 2
The images 2R and 2G are magnified by the projection lens system 4 and projected onto a screen (not shown).

In this way, a color projection image is obtained on the screen in which both images 2R and 28G are superimposed.

The first cathode ray tube IR has a monochromatic cathode ray tube configuration, and its phosphor screen is made of a red phosphor such as a rare earth phosphor such as Y2O2.
S:Eu1 or YVO4:Eu is coated on one surface, and a reproduced image 2R is obtained by scanning, for example, a single beam on the phosphor screen with density modulation.

The second cathode ray tube 1BG has a two-beam single electron gun as shown in FIG. 4, for example, and scans the phosphor screen S with two electron beams BB and Bc for blue and green emitted from the gun.

And an aperture grill A having a slit SL for the phosphor screen S.

Electrodes for determining the electron beam arrival position are arranged.

In the electron gun, for example, two cathodes KB and Kc corresponding to front and green are arranged in a horizontal plane, and a common first grid G (control electrode) and a second grid G2 are connected to the cathodes KB and Kc. (accelerating electrode) and a third grid G3 that constitutes a common unipotential electron lens, for example.
(first anode), fourth grid G4 (focusing electrode), fifth grid
Grids G (second anodes) are arranged in sequence, and convergence means C is arranged after the fifth grid G.

Thus, electron beams B8 and B are emitted from cathodes KB and KC, respectively.

are made to intersect approximately at the center of the unipotential type main electron lens constituted by the third to fifth grids, and at a position where they intersect with each other and are further apart, convergence is performed again by the convergence means C. and reaches the top of the phosphor screen S.

The convergence means C includes, for example, a deflection electrode plate C1 at the center and deflection electrode plates C2 and C3 on both sides.A deflection electrode plate C1 at the center of the waist and deflection electrode plates C2 and C on both sides.
A convergence voltage is applied between the two beams BB and C to convergently deflect the beams BB and C.

Also, an aperture grill A for use as an electrode for determining the arrival position of the electronic beam.

For example, as shown in FIG. 4, the electron beams BB and .

A large number of slits SL extending in the vertical direction, that is, the direction substantially orthogonal to the horizontal direction, are arranged.

For example, as shown in FIG. 5, the phosphor screen S has blue and green phosphor stripes B and G in a direction approximately perpendicular to the arrangement direction of the two beams, that is, in the extending direction of the slit of the aperture grille AG. They extend along the line and are arranged alternately.

In this way, the two electron beams BB and C emitted from the electron gun enter the slit SL of the aperture grill AC at the required angle of incidence and pass through the slit SL of the aperture grill AC, thereby causing the phosphor screen S.
The phosphor stripes B and G of corresponding colors are selectively lined.

The example shown in FIG. 5 is a case where the widths of the phosphor stripes B and G of the phosphor screen S are made approximately equal to each other, and in this case,
The width Wsp of the spots SPB and SPo of each beam that lines the phosphor screen S through the slit SL of the aperture grille AG can be selected to be smaller than or equal to the width Wp of each phosphor stripe B and G. For example, as shown in FIG.
The aperture ratio of the slit SL is selected to be, for example, more than 1 and less than 2 C of the total effective area.

For example, when 1 pitch (distance between the centers of adjacent slits SL) is 100%, the aperture ratio of the slit SL is 62.5%.
and thus the width Wsp of each spot SPB and SPc
is larger than the width of the phosphor stripe 100% Wp (2 = 50%), and when the spot 5PcSPc of each beam is at its normal position, the corresponding blue and green phosphor stripes B and G are located on both sides of the spot 5PcSPc. Each stripe G and B is made to land so as to overlap each other over a width (area) of, for example, 12.5% of (Wsp-Wp) as a whole.

In this case, each part of each phosphor B and G is hit twice by the beam corresponding to the other color, so the brightness here can be increased, resulting in a bright image 28G as a whole.
is obtained.

Further, as another example, as shown in FIG. 7, the aperture ratio of the slit SL of the aperture grille AG is selected to be, for example, 50%, and each width WP8 of each phosphor stripe B and G of the phosphor screen S is set.
and WPc may be unequal to each other such that Wp B <W2o.

In this case, WPB is, for example, 37.5% and Wp c is 62%.
．． Selected as 5%.

According to the device of the present invention described above, the image 2R of the red component is the first
With the cathode ray tube IR, the blue and green components of the image 2B
and 2G are obtained by the second cathode ray tube IBG, so a brighter projected image can be obtained compared to the single tube type projection device shown in FIG.

That is, in a normal three-color cathode ray tube, the aperture ratio of the slit SL of the aperture grill AC is at most 20%,
The remaining 80% of the electrons impact the aperture grille AG itself, and their energy is converted into heat and lost.

In comparison, according to the two-color color cathode ray tube IBG, the opening ratio of its aperture grille is 20% when the three colors are used.
Even if you simply convert it into the aperture ratio for two colors,
The brightness is about 30% of 1.5@ for three colors, and the brightness can be improved accordingly, but especially in this invention, these two color cathode rays It is characterized in that the tube is a two-color cathode ray tube IBG with a combination of blue and green, and by doing so, it is possible to further improve the brightness.

That is, in this invention, as mentioned at the beginning, we take advantage of the fact that the human visual sensitivity is not so noticeable even when blue and green colors are mixed with each other. As shown in FIG. and SPB, so to speak, double irradiation is performed.

Therefore, although color mixture will occur in this area, the brightness will be approximately twice as bright.

In this example, the reason why the aperture ratio of the electrode for determining the electron beam arrival position, such as the slit SL of the aperture grille AC, is selected to be 9 or less is because if it exceeds this, the mixture of both colors becomes an eyesore. Due to this.

Furthermore, as in the example shown in FIG. 7 above, the widths of the blue and green phosphor stripes B and G are made different, for example,
The width of the green phosphor stripe G with high luminous efficiency is made larger than the width of the blue phosphor stripe B with low luminous efficiency,
It is also possible to make the beam spot corresponding to blue straddle and impact the green phosphor stripe G, and in this case as well, there is a wide green phosphor stripe G with high luminous efficiency. Since the beam is made to impact this, the blue and green images will be greenish, but the brightness can be improved.

Even in this case, the color mixture of green and blue does not cause much of an eyesore, so there is no substantial problem with the color mixture.

In particular, since color images projected by a color image projection device such as the device of the present invention are generally projected over a large area in a dark place, color fidelity is not so required. What is required is a bright image, and considering this point, by configuring a two-color tube with a combination of green and blue, even if there is a mixture of colors between the two, it will not be an eyesore to the viewer as a whole. This makes it possible to obtain images of excellent quality.

In addition, Fig. 8 shows a chromaticity diagram, and the solid line a in the figure shows the reproduction range of a three-tube color image projection device that obtains red, green, and blue images using independent color cathode ray tubes. , the dashed line in the same figure indicates the color cathode ray tube I, which consists of the blue and green two-color tube IBG and the red one color tube according to the present invention explained in FIGS. 3 to 5.
This shows the reproduction range when R is used.

Further, according to the above-described apparatus of the present invention, the optical image of the red image 2R from the first cathode ray tube IR and the blue and green images 28G of the second cathode ray tube IBG are converted into a red image by the dichroic mirror 7. The optical image regarding IR reflects this,
The blue and green images 28G are transmitted through this to combine the two, but according to the above-described configuration of the present invention, the characteristics of the dichroic mirror 7 can be easily selected.

In other words, both high-quality images 2R and 28G can be effectively reflected and transmitted to obtain a high-quality projected image.

That is, when a rare earth phosphor is used as a red phosphor, the emission spectra of the red, green, and blue phosphors are distributed as shown by curves 10R, 10G, and IOB in FIG. Since the emission wavelengths of red and green exhibit adjacent distributions as shown in the same figure, the characteristics of the dichroic mirror 7 are as shown in the broken line C in FIG. In the wavelength range,
The selection of the material for the dichroic mirror 7 was based on the fact that it would be sufficient to use a material that has a filter effect that exhibits reflection characteristics in the right side of the broken line C, that is, in the direction of large wavelengths, and that exhibits transmission characteristics in the region of small wavelengths. becomes easier.

Moreover, when a rare earth phosphor is used as the red phosphor and its wavelength distribution curve 10R is steep, that is, narrow, as shown in FIG. 9, the green wavelength distribution curve 10R is
Since the interval between the G and red wavelength distribution curves 10R can be increased, the characteristics of the dichroic mirror are such that it has a boundary wavelength between transmission and reflection in the wide wavelength range of both. It is easy to select the characteristics, and conversely, it is possible to reliably reflect the red image and transmit the blue and green images without waste, so it is possible to obtain a high-quality color projection image. It's something that can be done easily.

In the above example, a second color cathode ray tube with blue and green dichroic tubes is used as a two-beam single electron gun, but the configuration is not limited to this, and a two-beam two-electron gun structure is also applicable. 1. For blue and green, multiple beams are superimposed and landed on the phosphor screen. It will be obvious that various changes can be made without being limited to the above-mentioned example, such as a different configuration.

[Brief explanation of drawings]

1 and 2 are route maps of conventional color image projection devices, FIG. 3 is a route map of an example of the color image projection device according to the present invention, and FIG. 4 shows the constituent countries of the two-color cathode ray tube. 5 is an explanatory diagram of a two-color cathode ray tube, FIGS. 6 and 7 are diagrams showing the relationship between the phosphor screen, the aperture grille, and the beam landing spot on each side of the two-color cathode ray tube of the apparatus of the present invention, and FIG. The figure is a chromaticity diagram used to explain the device of the present invention, and Figure 9 is red.
FIG. 3 is an emission spectrum diagram of green and blue phosphors. 1R is the first cathode ray tube that reproduces the single primary color of red, 2R is its reproduced image, IBG is the second cathode ray tube that reproduces the two primary colors of blue and green, AC is the aperture grill that becomes the electrode for determining the electron beam arrival position, and SL is the slit of aperture grill AG, S
is a phosphor, B and G are blue and green phosphor stripes,
SPB and SPc are the landing spots of the electron beam corresponding to front and green, respectively.

Claims (1)

[Scope of utility model registration request] A first cathode ray tube that reproduces images using a single primary color of red, an electron gun that emits electron beams corresponding to blue and green, and a phosphor screen in which blue phosphors and green phosphors are alternately arranged. a convergence means for deflecting each of the electron beams so as to coincide with each other on the phosphor screen; a second cathode ray tube for obtaining a reproduced image in two primary colors of blue and green, which has an electrode for determining the electron beam arrival position in which a plurality of through holes are formed for the electron beam to reach the center; and an image produced by the first cathode ray tube. and the second above
and a projection means for projecting images from a cathode ray tube so as to overlap each other on a screen, and the width of the through hole of the electrode for determining the electron beam arrival position is wider than the width of at least one of the phosphors. A color image projection device featuring: