JPS5928785A - Video projector - Google Patents

Abstract

PURPOSE:To attain the simplicity of a circuit and rational adjustment, by making the optical axes of monochromatic light from each monochromatic cathode ray tube coincident with an optical means and setting vertically each optical axsis on a screen. CONSTITUTION:Blue light from a blue cathode ray tube 1 and red light from a red cathode ray tube 3 are made respectively incident to triangle prisms 11, 13, and green light from a green cathode ray tube 2 is made incident to a trapezoidal prism 12. A prism device comprising the prisms 11-13 makes the light axes of each monochromatic light from the cathode ray tubes 1-3 coincident, the blue, the green and the red light whose optical axes are made coincident are irradiated from the prism 11 and projected vertically on the screen 7. An optical path length in the prism of each monochromatic color is equal and the raster of the cathode ray tubes 1-3 is projected on the screen 7 in the same size. Thus, the raster of each color light on the screen 7 is placed within distances W1, W2 equal from a center point C, no deformation exists horizontally and vertically and a square raster having a specified rate is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is an image that displays an enlarged color image by enlarging and combining different monochrome images projected on a projection type cathode ray tube onto a screen and projecting the same. This invention relates to a projection device.

As the demand for increasing the size of the 114Ii image reproduction surface of television receivers to obtain more powerful images that cannot be obtained with smaller screens has increased, the image reproduced on the fluorescent surface of a cathode ray tube is projected onto a lens, etc. Video projection devices that use optical systems to project onto a screen to obtain large-sized television images have become widely used.In order to obtain large-sized color television images, a single color By enlarging and projecting a color television image projected on a cathode ray tube onto a screen, it is difficult to obtain a large color television image with sufficiently high brightness and low resolution. Project the image 3
These monochromatic cathode ray tubes are used, and these monochromatic images are respectively enlarged and displayed on the screen in combination.

Figure 1 shows a plane 1"41 showing an example of a conventional image projection device.
1 is a blue emission projection type cathode ray tube 2 is a green emission projection type cathode ray tube 5 is a red emission projection type cathode ray tube,
4.5 and 6 are projection HL lenses, and 7 is a screen.

-[hj In the diagram, the blue image projected on the blue emission projection type cathode ray tube (hereinafter referred to as blue cathode ray tube) 1 is
The green image is enlarged by a projection lens 4 and projected onto a screen Z, and projected onto a green emission projection type cathode ray tube (hereinafter referred to as a green cathode ray tube) 2. The green image is enlarged by a projection lens 5 and projected onto a screen Z. Further, the red l[iII image projected on a red emitting projection type cathode ray tube (hereinafter referred to as a red cathode ray tube) is magnified by a projection lens 6 and projected onto a screen Z. The blue, green, and red images are projected onto the screen 7 in a superimposed manner, so that the screen 7 displays an enlarged color preview image. Note that the screen 7 may be of either a reflective type or a transmissive type.

In such an image projection device, each cathode ray tube 1, 2 .
The arrangement of No. 3 is a typical arrangement, but in consideration of human visibility, the green cathode ray tube 2 is placed in the center, and the blue cathode ray tubes 1 are placed on both sides of it. It is common to arrange a red cathode ray tube 6.

-Also, the projection optical axes of each monochrome cathode ray tube 1, 2.3 are arranged in the same plane, and each projection optical axis is aligned with the screen 7.
The blue cathode ray tubes 1. The projection optical axes of the red cathode ray tubes B are tilted in opposite directions by a predetermined angle α, and furthermore, the distances from the screen 7 to each monochromatic cathode ray tube B are selected to be equal to
The moon lenses 4, 5.6 are arranged at predetermined positions on the projection optical axis in order to obtain the necessary projection magnification.

As described above, in the conventional video projection device, the green image from the green cathode ray tube 2 is projected vertically onto the screen 7, whereas the blue image from the blue cathode ray tube 1 and the red image from the red cathode ray tube 3 are projected vertically onto the screen 7.
The red image is projected diagonally onto the screen 4.

Therefore, if the raster formed on each monochromatic cathode ray tube 1, 2.3 is a rectangle with exactly the specified ratio, then the raster projected on the screen 7-H by the green cathode ray tube 2 will be a rectangle with exactly the specified ratio. , monochrome cathode ray tube 1,6
Therefore, the raster on the screen Z will not be a rectangle with a specified ratio. In other words, if we look at horizontal scanning now,
The light beams on the projection optical axes of the monochromatic cathode ray tubes 1, 2.3 intersect at the center point C of the screen 7, and the light beams at the raster ends are projected at a deflection angle θ with respect to the projection optical axis and are completely imaged on the screen Z.

Since the projection optical axis of the green cathode ray tube 2 is perpendicular to the screen 7, the raster edge on the screen Z is aligned with the screen 7.
A position G+ at an equal distance in the horizontal direction from the center point C of
G2, but in the case of the blue cathode ray tube 1, the projection optical axis is tilted at an angle α with respect to the line perpendicular to the screen 7, so there is a difference between one raster edge and the other raster edge from the screen of the cathode ray tube 1 to the screen. The optical path length at 71 is different,
Therefore, one raster edge on screen 7 is at position G1
The innermost position is B1, and the other raster end is at position G2.
This is the outer position B2. For the same reason, in the case of the red cathode ray tube B, one raster end on the screen 7 is at position R1 outside position G1, and the other raster end is inside position G2 (at position R2 of 111).

However, the raster produced by the blue cathode ray tube 1 on the screen 7 is at a distance CB on the right side when viewed from the blue cathode ray tube 1 side.
+, and the left side is expanded to a distance CB2. On the contrary, the raster produced by the red cathode ray tube 3 on the screen 7 is expanded to the distance CR+ on the right side and compressed to the distance CR2 on the left side when viewed from the red cathode ray tube 30Ill.
Although we have invented horizontal raster scanning, for the same reason, raster compression and expansion also occur in vertical scanning, and as a result, as shown in Figure 2, the green color on the screen 7 is The raster 9 created by the cathode ray tube 2 becomes a rectangle with a specified ratio, but the raster 8 created by the blue cathode ray tube 1 becomes a trapezoidal raster that narrows by 111 degrees to the right, and the raster 1 [] created by the red brown negative becomes a trapezoidal raster that is the opposite of that. . The shapes of these rasters are when the screen 7 is a reflective type and is viewed from the 1°2.3 side of a monochrome cathode ray tube.If the screen 7 is a transmissive type, 8 is a red cathode ray tube in FIG. 10 is a raster generated by the blue cathode ray tube 1.

Shape distortion due to such expansion and contraction of the raster causes color shift on the screen 7'', that is, misconvergence. In order to correct this misconvergence, conventionally, a convergence yoke was installed at the neck of each single-color cathode ray tube (1.2.3), and a drive circuit applied a correction current to the convergence yoke to correct the screen of each color. The raster shape distortion on Z is eliminated and the rasters of each color are made to match. However, such correction means requires a large-scale and complicated circuit configuration;
The drawback was that adjustment was complicated and difficult.

In addition, in the conventional image projection device described above, the blue cathode ray tube 1
Since the projection optical axis of is set obliquely to the screen 7, for example, if the screen 7 is a reflective type,
When the color television image on the screen Z is observed from the direction of the reflection extension line of the projection optical axis by the screen 7, the blue color is emphasized and the entire image becomes bluish. Further, when the screen 7 is of a transmission type, the image similarly becomes bluish when observed from an extension of the projection optical axis of the blue cathode ray tube 1. Similarly, since the projection optical axis of the red cathode ray tube filter is also set diagonally to the screen 7, a floating-floor image is observed depending on the observation position, and the color television image on the screen 7 depending on the observation position. Another drawback is that the so-called color ft phenomenon occurs, in which the color tone changes.

An object of the present invention is to eliminate the drawbacks of the prior art described above, and to be able to project each monochrome cathode ray tube raster onto a screen without causing shape distortion. i, 'fI Image projection device HH1 that does not cause color shift due to M position 1.
3. In order to achieve this object, the present invention makes the optical axis of the valley monochromatic cathode ray tube -H by optical means, and the optical path length from the screen to the valley monochromatic cathode ray tube 1. It is characterized by the fact that they are made equal.

Hereinafter, embodiments of the present invention will be explained with reference to the drawings. 1. Figure 1 shows a flat surface 1 showing an embodiment of the image projection device according to the present invention, -11 is a triangular frame for blue light;
2 is a trapezoidal prism for green light, 16 is a triangular prism for red light, and 14 is a projection lens, and parts corresponding to those in FIG. 1 are given the same reference numerals.

In FIG. 6, blue light from a blue cathode ray tube 1 enters a triangular prism for blue light (hereinafter referred to as a triangular prism) 11, and green light from a green cathode ray tube 2 enters a trapezoidal prism for green light (hereinafter referred to as a trapezoidal prism). The red light from the red cathode ray tube is input to a triangular prism for red light (hereinafter referred to as a triangular prism) 10.

A prism device consisting of triangular prisms 11 and 1 and a trapezoidal prism 12 is a blue cathode ray tube 1. green cathode ray tube 2
The optical axes of the monochromatic lights from the red and red cathode ray tubes are aligned, and the blue, green, and red lights whose optical axes are aligned are emitted from the triangular prism 11, pass through the projection lens 14, and are projected vertically onto the screen Z. Projected. Each monochrome cathode ray tube 1,
The optical path length of each monochromatic light beam from 2.5 degrees within the prism is equal, so the rasters of each monochromatic cathode ray tube 1 degree 2.3 are magnified to the same size by the projection lens 14 and projected onto the screen Z. Therefore, the rask of each color light on the screen Z is located within the positions W+ and w2, which are the same distance from the center point C, and there is no shape distortion in the horizontal direction, and similarly there is no shape distortion in the vertical IM direction. As shown in FIG. 4, a rectangular raster 15 of a prescribed ratio is obtained.

FIG. 5 is a block diagram showing a specific example of the prism device shown in FIG. 5, and parts corresponding to those in FIG. 6 are given the same reference numerals.

In FIG. 5, the triangular prism il, 13 and the trapezoidal prism 12 have shapes when glass with a refractive index of 17 is used. The angle with the axis is 1
Selected at 22 degrees 1. I'm here.

1. The blue light on the projection optical axis from the blue cathode ray tube 1 is
The light enters the triangular prism 11 from point a at point L2.

At point l), the blue light is totally reflected, reaches point C, is reflected again at point C, and is emitted from the point to the outside of the prism. Next, the red light on the projection optical axis from the red cathode ray tube passes through the triangular prism 1.
3, is reflected at point g+e, travels straight through the triangular prism 11 from point C, and exits the prism from the point. Here, the optical path length fg of the red light inside the triangular prism 13
+ge+ec is the optical path length a of the blue light inside the triangular prism 11
equal to b+bc, and the reflection angle IBj' in the prism
By setting the shapes of the triangular prisms 11 and 13 in consideration of the above, blue light and red light are emitted along the same optical axis.

Light with a projection optical axis F from the green cathode ray tube 2 enters the trapezoidal prism 12 at point d, and enters the triangular prism 1' from points e and c.
r, 11, and is ejected from the point to the outside of the prism. Here, the optical path length de of the green light within the trapezoidal prism 12 is
Blue light, green light by setting equal to the optical path length fg+ge.

The optical path lengths of the red lights are all equal, and the optical axes within the prism 11 are all coincident.

As shown below, the blue light, green light, and
Each image of red light is magnified by a common projection lens and projected onto the screen 7 (Fig. 6), but since the magnification of all color light images is equal and the optical path length of each colored light is equal, The rasters of each color light on the screen 7 match and shift in color,
That is, no misconvergence occurs. Since the projection optical axis of each color light emitted from the prism device is perpendicular to the screen 7, the shape of the raster on the screen 7 becomes a rectangle with a specified ratio without distortion. Therefore, −
Raster distortion 1 for g color cathode ray tube 1° and red cathode ray tube 3
It does not require any other complicated comparability means.

In addition, since the optical axes of blue light, red light, and green light are aligned, it is suitable for vertical observation. No color shift of the color television image on the screen Z occurs.

Note that the refractive index, shape, etc. of the prism shown in FIG. 5 are merely shown as an example, and are not limited thereto.

As explained above, according to the present invention, the monochromatic light beams 44+ from the valley monochromatic cathode ray tubes are made to coincide with each other, and the optical axis is set perpendicular to the screen, so that one monochromatic image of each monochromatic cathode ray tube is Since the image is enlarged and projected onto a two-screen screen, there is no need for complicated and difficult-to-adjust convergence adjustment means for each single-color cathode ray tube, and the circuit can be simplified and adjustments can be streamlined. To provide an image projection device which can obtain a high quality enlarged cuff television image without causing a color shift in the color television image, and which has excellent functions by eliminating the drawbacks of the prior art. can.

[Brief explanation of drawings]

Figure 1 is a plan view showing an example of a conventional video projection device;
The figure is a schematic diagram showing the shape of a raster formed by each monochrome cathode ray tube projected onto the screen in Figure 1, Figure 3 is a plan view showing an embodiment of the video projection device according to the present invention, and Figure 4 is the diagram shown in Figure 5. FIG. 5 is a schematic diagram showing the shape of a raster formed by each monochromatic cathode ray tube projected onto the screen of FIG. 1.2. Monochromatic cathode ray tube 7...Screen 1
1.13...Triangular prism 12 Trapezoidal prism 1
4. Projection lens 2 Figure 3 Figure 4

Claims (1)

[Scope of Claims] Monochrome images projected on each of a blue emission projection type CRT, a green emission projection type CRT, and a red emission projection type CRT are enlarged and composited and projected onto a screen by a projection/lens. In a video projection device for displaying a color image, a prism device is provided that receives monochromatic light from each of the projection type cathode ray tubes and makes the optical axes of the monochromatic lights coincide, and the optical axes that are coincident are aligned with the surface of the screen. An image projection device characterized in that the image projection device is configured to be perpendicular to the direction of the image projection device. (2) In claim (1), the prism device includes a trapezoidal prism through which green light from the green light emitting projection cathode ray tube passes straight through, and a trapezoidal prism that passes the green light passing through the trapezoidal prism and the red light emitting projection. a triangular prism that receives red light from a projection type cathode ray tube and reflects the red light so that its optical axis coincides with the optical axis of the green light; and a green light whose optical axis coincides with the blue light from the blue light emitting projection type cathode ray tube. and red light are incident thereon, and the blue light is reflected so that its optical axis is aligned with the optical axis of green light and red light.