JPS6222511B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a multi-tube projection type color television receiver using a plurality of color projection tubes.

The conventional projection color television receiver became the first
As shown in the figure. The most common one is a monochromatic projection tube 1R, which has phosphors in each of the primary colors of red, green, and blue.
This is a device that projects and enlarges images of 1G and 1B onto a screen 3 using lenses 2R, 2G, and 2B, respectively. In order to obtain brightness on the screen image in this projection device, high gain (high directivity) is applied to screen 3.
When using a screen, three projection tubes 1R, 1
Due to the difference in the angle of incidence of G and 1B on the screen 3,
The angle of the image projected on the screen 3 changes depending on the viewing position. For example, if the viewing position is 4, the image will appear red, and if viewed from 5, it will appear blue.

As the arrangement of the three projection tubes, an in-line arrangement as shown in FIGS. 2a and 2b and a delta arrangement as shown in FIG. 2c have been proposed and put into practical use when viewed from the screen side. However, both have the disadvantage that chromaticity changes depending on the viewing position for the reason mentioned above.

On the other hand, the brightness on the screen is approximately given by the following equation.

Bs=Bc・Gs・η/4F ² (1+m ² ) (Bc: Projection tube brightness, Gs: Screen gain, η:
Efficiency of the optical system, F: lens brightness, m: image magnification) From the above formula, in order to increase the brightness of the projection section, either increase the size of each projection tube to decrease the image magnification, or increase the lens aperture. It is necessary to increase the brightness F of the lens by increasing it, or to increase the brightness of the projection tube. As can be seen from Figure 1, when the former projection tube and lens aperture are increased, the difference in the angle of incidence between the projection tubes 1R, 1B and 1G becomes even larger due to their mechanical configuration, and the chromaticity changes depending on the viewing position become larger. Occur.

On the other hand, an increase in the brightness of the projection tube affects the lifespan of the phosphor, and it is generally said that the lifespan of the phosphor is determined by the amount of charge applied to the phosphor. The main phosphors used in recent projection tubes are RMA numbers such as P ₂₂ (R) for red, P ₁ or P ₄₃ for green, and P ₂₂ (B) for blue. And the brightness of these phosphors is 1/2
The amount of charge required to drop to P ₁ : >100C/
cm ² , P ₄₃ :>50C/cm ² , P ₂₂ (B): 20 to 30C/cm ² . As described above, the life span differs depending on the projection tube, and when used for a long time, the white balance of the screen image changes. Therefore, if a high amount of charge is applied to increase brightness, the lifetime will be shortened.

The present invention is to provide a projection type color television receiver which reduces the above-mentioned drawbacks, has a long lifespan, has a high luminous flux, and further reduces color change depending on the viewing position.

Figure 3 shows an embodiment of the present invention, in which figure a shows the arrangement of the projection tube as seen from the screen side, and figure b shows the arrangement of the projection tube as seen from the screen side.
shows a side view of this embodiment. Red as shown in Figure 3,
a projection tube 1R having phosphors of each primary color of green and blue;
Lenses 2R, 2G, corresponding to 1G, 1B, 1B'
2B and 2B' are arranged, and the projected images are superimposed on the screen 3, and the screen 3 is a high gain (high directivity) screen. In this embodiment, a total of two blue tubes 1B and 1B' are used, and these blue tubes are vertically arranged symmetrically with respect to the midpoint O of the four projection tubes. When the viewing position on the screen 3 side is at the center 6, drive circuits for the projection tubes 1R, 1G, 1B, and 1B' are determined so that the white balance is appropriate. Here, the brightness of the blue tubes 1B and 1B' is approximately the same, and is approximately half that of the conventional blue tube used in FIG. 2c, for example. With the above configuration, when the viewing position changes to 5, the white balance of the screen image is such that the light from blue tube 1B feels stronger than when viewed from 6, but the light from blue tube 1B' is reflected in 4 directions by screen 3. It is felt to be very weak, and as a result, the blue component of the image hardly changes.

On the other hand, the light from the red tube 1R and the green tube 1G seems weaker than when viewed at 6, and therefore the white balance when viewed at 5 is a little bluer than the white balance when viewed at 6, but it is sufficient for practical use. Note that the white balance seen in 4 is simply the relationship in which 1B and 1B' of the blue tube are swapped, so the result is the same as in the case seen in 5 above.

In this embodiment, color changes depending on the viewing position can be greatly reduced. In other words, in the conventional delta layout as shown in Figure 2c, the white balance changes to blue-white-yellow when viewed while standing or sitting.
In this embodiment, it is possible to suppress a slight change in chromaticity around white. Furthermore, when considering the lifespan of each tube, even blue tubes, which have a much shorter lifespan than red tubes when driven at the same brightness as in the past, can be used at approximately half the brightness as in this example. This makes it possible to significantly extend the lifespan of each tube, making it easier to balance the lifespan of each tube, and extending the overall lifespan compared to the past, where the lifespan of the entire device was almost determined by the blue tube. It became possible. On the other hand, if the device is designed to have the same lifespan as conventional devices, each tube can be driven to even higher brightness, making the image on the screen even brighter.

FIG. 4 shows the arrangement of the projection tubes as seen from the screen side in another embodiment using four tubes. Similar to Figure 3,
Two blue tubes 1B and 1B' are used and are arranged symmetrically about the midpoint O. The brightness of the blue tubes 1B and 1B' is driven to be half of that of the conventional one shown in FIG. 2a, for example. When the viewing position of the screen changes to the left or right, the changes in the light from the blue tubes 1B and 1B' cancel each other out, and the white balance remains slightly reddish and greenish compared to the white at the center. Note that if you change the viewing position above or below the screen, the chromaticity of the screen image will not change.

This embodiment improves the change in white balance depending on the viewing position in the conventional inline arrangement shown in FIG. 2a, and is similar to the embodiment shown in FIG. The lifespan of the tubes can be balanced, and it is also possible to extend the lifespan or provide a higher amount of charge to each projection tube.

Figure 5 shows an example in which five monochrome projection tubes are used: red tube 1R, green tube 1G, 1G', blue tube 1B,
Consists of 1B'. This is because, as mentioned in the conventional example, the phosphor of recent projection tubes is P ₂₂ as a red phosphor.
(R), P ₁ or P ₄₃ is used as the green phosphor, and P ₂₂ (B) is used as the blue phosphor. In order to obtain a white screen image with a color temperature of around 9300°, the driving current for each projection tube is , red tube 1
If so, approximately 1.4 is required for green tubes and 2 for blue tubes. In this embodiment, two green tubes and two blue tubes each having insufficient luminance ratio are used. The configuration of the projection tube as seen from the screen side is that the red tube 1R is placed in the center, the green tubes 1G and 1G' are placed symmetrically, and the blue tubes 1B and 1B' are placed symmetrically with respect to the midpoint O of the 5 tube configuration. Now, if we make the brightness of green tubes 1G and 1G' the same, and the brightness of blue tubes 1B and 1B' the same, the color change of the screen image depending on the viewing position will be as follows: Changes in reflected light from 1B and 1G and 1G' and 1B' cancel each other out, and 1B and 1G in the left and right directions cancel each other.
The changes in the reflected light of B, 1G' and 1G, 1B' are canceled out. Therefore, the chromaticity change in the white balance of the screen image in the vertical and horizontal directions is even smaller than in the embodiments described above. Further, the drive currents of each projection tube are almost balanced, and it is also possible to provide a higher amount of charge to each projection tube, resulting in a projection section with high optical output.

In the above embodiments, a lens-type projection tube has been described, but similar effects can be obtained with Schmidt optical projection tubes, projection tube light valves with built-in reflection mirrors, and the like.

It is clear that the chromaticity difference and luminance difference between projection tubes of the same color can be used within the scope of the idea of the present application.

As is clear from the above embodiments, the present invention provides a multi-tube type receiver with four or more tubes compared to the conventional three-tube type projection color television receiver, thereby increasing the light output or life span of the conventional three-tube projection color television receiver. To provide an excellent multi-tube projection type color television receiver which reduces the color change of a screen image depending on the viewing position, which is a drawback of the three-tube type.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the main parts of a conventional projection type color television receiver, FIG. 2 is a block diagram of the arrangement of a conventional projection tube, FIG. 3 is a block diagram of an embodiment of the present invention, and FIG.
5 and 5 are arrangement diagrams of a projection tube according to another embodiment. 1R...Red tube, 1G, 1G'...Green tube, 1B,
1B'...Blue tube, 3...Screen.

Claims (1)

[Scope of Claims] 1. A projection type color television receiver that projects and superimposes images from projection tubes projecting different colored lights onto a screen, including a plurality of projection tubes projecting at least one colored light, And the total number of projection tubes is 3+n (n>1, n≠3m and n, m
is an integer), and causes the plurality of projection tubes of the same color to emit light with approximately the same brightness, and when viewed from the screen side, is symmetrical with respect to the midpoint of the 3+n projection tubes. A multi-tube projection type color television receiver characterized by the following: 2. The multi-tube projection type according to claim 1, which is equipped with projection tubes that project red, green, and blue colored light, of which two projection tubes project blue colored light. Color television receiver.