JPS62194788A - Projector - Google Patents

Abstract

PURPOSE:To improve the unnatural video image like a mosaic by shifting sequentially and relatively red/green/blue video images in horizontal or vertical direction so as to increase apparent number of picture elements. CONSTITUTION:Picture elements DR1-1-DR2-2 produced by a liquid crystal cell of a crystal board for red color corresponding with reference to picture elements DB1-1-DB2-2 produced by a liquid crystal cell of a blue liquid crystal board 101 on a screen 14 and displayed at a position deviated horizontally by 2/3 picture element. In addition, picture elements DG1-1-DG2-2 produced by a liquid crystal cell for the blue liquid crystal board 10 are displayed at a position deviated horizontally by 1/3 picture element. Thus, the video image on the screen 14 in its picture element number in the horizontal direction is increased by nearly 3 times apparently.

Description

[Detailed Description of the Invention] A. Industrial Application Field The present invention relates to a projector, and is particularly suitable for application to a projector that uses a transmissive liquid crystal panel to display color images on a screen. .

B Summary of the Invention The present invention forms red, green and blue image light by using transmission type liquid crystal panels for red, green and blue.
In a projector designed to display a color image by projecting this image light onto a screen, an attempt was made to improve the image quality of the projected image, which looked rough like a mosaic, by sequentially shifting the projected images of each color on the screen. It is something to do.

C. Conventional technology Conventionally, this type of projector has used three transmissive liquid crystal panels for red, green, and blue to form red, green, and blue image light, and to project this image light onto a screen. A device configured to display a color image by projecting it onto the screen is used.

That is, as shown in FIG. 4, a white light source 2 is arranged in front of the optical axis A red dichroic mirror 3, a green dichroic mirror 4, and a reflecting mirror 5 are arranged in this order.

The dichroic mirror 3 for red color transmits light rays other than the red light range among the light incident from the condensing lens 1, and separates the light ray LR in the red light range, and sends it to the red color liquid crystal via the reflecting mirror 6. A light beam LR in the red light range is supplied to the plate 8.

Similarly, the dichroic mirror 4 for green transmits the light rays other than the green light range out of the light transmitted by the dichroic mirror 3 for red, and also separates the light ray LG in the green light range and passes it through the reflecting mirror 7 to the green light. A light beam LG in the green light range is supplied to the liquid crystal plate 9 for use.

Reflection w#, 5 transmits the so-called blue light ray LB from which the red light range and green light range light rays LR and LG are removed from the white light by passing through the red and green dichroic mirrors 3 and 4. By bending it, this light beam LB in the blue light range is supplied to the transmission type liquid crystal plate IO for blue color.

The liquid crystal plates 8.9 and 10 are formed by arranging liquid crystal cells of the same shape in a matrix whose transmittance changes depending on the applied voltage, and each liquid crystal cell serves as one pixel for image light LRo, LGO.
, LBo are formed.

On the optical path of the image light LB of the liquid crystal plate 10 for blue color, a dichroic mirror 11 for green color is arranged in parallel with the reflecting mirror 7 on the intersection with the image light LG of the liquid crystal plate 9 for green color. Further, a dichroic mirror 12 for red is arranged parallel to the reflecting mirror 6 on the intersection of the liquid crystal plate 8 for red with the image light LR.

Thus, the image light LR0 obtained from the liquid crystal plate 8.9.10
, LGo, and LBo are combined and projected onto the screen 14 via the field lens 13.

In the above configuration, the voltage applied to the liquid crystal cells of each liquid crystal plate 8, 9 and 10 is changed by, for example, the red, green, and blue color signals of the television video signal. As a result, the liquid crystal plates 8.9 and IO will generate red, green, and blue images, respectively.

Here, the optical path lengths of the light rays in the red, green, and blue light regions from the white light source 2 to the screen 14 are selected to be equal, and the light rays in each light region from the liquid crystal plates 8.9 and 10 to the screen 14 are selected to be equal. If the optical path lengths are selected to be equal, red, green, and blue images of equal size can be obtained on the screen 14.

Therefore, for example, can the liquid crystal plates 8 and 9 be moved vertically? By adjusting the angle XX and adjusting the inclinations of the reflecting mirrors 5.6 and 7, the red and green images can be superimposed on the blue image on the screen 14 with sufficient accuracy for practical use. That is, as shown in FIG. 5, pixels D B on the screen 14 generated by the liquid crystal cells of the blue liquid crystal plate 10
, -, ~DBz-z, the corresponding pixel D R+-+ "" is generated by the liquid crystal cell of the red liquid crystal plate 8.
When adjusting so that the pixels DG + -+ to DG t-2 generated by the liquid crystal cells of the liquid crystal plate 9 and the green liquid crystal plate 9 are completely overlapped, one blue pixel area becomes one color display pixel area. can be obtained as

Thus, the red, green, and blue image lights LR, t, co, and L formed based on the red, green, and blue color signals
A color display image obtained by subtracting and mixing the Bo images can be projected onto the screen 14.

D Problems to be Solved by the Invention However, in a CRT (cathode ray tube) display for normal television reception, images are constructed using approximately several hundred thousand pixels.

Therefore, in order to realize images with the same resolution, it is necessary to provide the same number of liquid crystal cells on each liquid crystal board as the number of pixels, but in practice this number of liquid crystal cells must be placed on one board. It is extremely difficult to create a In general, the number of liquid crystal cells that can be created as a single liquid crystal plate is limited to tens of thousands of cells, and therefore the display images of liquid crystal projectors constructed using these cells have an extremely small number of pixels. , it is inevitable that the image will be grainy.

In particular, in a liquid crystal projector that projects an enlarged image onto a screen, the lack of pixels mentioned above not only reduces the resolution of the displayed image, but also causes the image to look unnatural to the viewer.

In other words, for example, a CRT display can display an image that gradually changes from bright to dark from left to right, but a projector using this liquid crystal display can display an unnatural image that changes from bright to dark in a stepwise manner. It will be displayed as a video.

Furthermore, an outline that can be displayed as a diagonal straight line on a CRT display is now displayed as an unnatural outline that changes stepwise in a mosaic manner with each liquid crystal cell as a unit.

The present invention has been made in consideration of the above points, and is a liquid crystal panel that improves the appearance of displayed images by increasing the number of pixels on the top, thereby improving the unnatural appearance of conventional images. This paper attempts to propose a color projector that was used in this project.

E Means for Solving the Problem In order to solve the problem, in the present invention, the red, green and blue lights LRXLG, LB are transmissive liquid crystal plates 8.9 for red, green and blue. By transmitting it through lO, red, green and n-color image lights LR0, LGo
, LBo, and the image light LRo, L, Go,
In a projector that obtains a color display image by projecting LB6 onto the screen 14,
The screen 1 is arranged so that the positions of the red, green and blue images by the red, green and blue image lights LR0, LGo and LBo are sequentially and relatively shifted in the horizontal and/or vertical direction.
Red, green, and blue image lights are projected onto 4.

When the red, green, and blue images produced by the F-effect red, green, and blue image lights LR6, LG, and LBo are sequentially and relatively shifted in the horizontal or vertical direction, the number of pixels above appears to be tripled. Produces an increased visual effect.

Furthermore, when the pixels are shifted in the horizontal and vertical directions, a visual effect is produced in which the number of pixels on the top appears to have increased by nine times.

In this way, the number of pixels on the top appears to increase, so it is possible to obtain a more natural-looking image, which is an improvement over the conventional unnatural mosaic-like image.

Embodiment G An embodiment of the present invention will be described in detail below with reference to the drawings.

In the projector in the first embodiment, as shown in FIG. 4, the position of the image displayed on the screen 14 by the red, green, and blue liquid crystal plates 8, 9, and 10 is sequentially 1/3 pixel in the horizontal direction. The other parts are constructed in the same manner as in FIG. 4, except for the flames, which are constructed to be shifted by a certain amount.

That is, as shown in FIG. 1 corresponding to FIG. 5, pixels D B 1- + to DI3z-t generated by the liquid crystal cells of the liquid crystal plate 10 for blue on the screen 14
The pixel D R+-+ "' D Rt-t generated by the liquid crystal cell of the corresponding red liquid crystal plate 8 is displayed at a position horizontally shifted by 2/3 pixel with reference to .

In addition to this, the pixel DB+-+-DB! generated by the liquid crystal cell of the blue liquid crystal plate IO! −, and the pixel D generated by the liquid crystal cell of the corresponding green liquid crystal plate 9
Ct-+ to DGz-t are displayed at positions shifted by 1/3 pixel in the horizontal direction.

In practice, such a positional shift can be realized by relatively shifting the positions of the liquid crystal plates 8.9 and 10 with respect to the optical axis.

In the configuration shown in FIG. 1, the image obtained on the screen 14 has a configuration in which red, green, and blue images are sequentially shifted by 1/3 pixel in the horizontal direction and superimposed.

In this way, the image on the screen 14 appears to have a visual effect as if the number of pixels in the horizontal direction has increased by approximately three times.

That is, as described above with reference to FIG. 5, when the red and green images are superimposed on the blue image without any deviation, the area corresponding to one pixel of the image on the screen 14 contains the red, green, and blue images. Information for one pixel is displayed by overlapping green and blue pixels. In contrast, the first
As shown in the figure, the area of one pixel on the screen 14 is divided into three small areas in the horizontal direction, and the content of red, green, and blue information differs for each small area, resulting in visually This produces an effect as if the number of pixels had tripled.

Therefore, according to the first embodiment, an image that appears to change smoothly in the horizontal direction can be displayed on the screen 14, compared to the conventional image that appears rough and unnatural like a mosaic.

FIG. 2 shows a second embodiment of the invention.

In the case of the first embodiment, a case has been described in which the red, green, and blue images are sequentially shifted in the horizontal direction, but in this case, they are shifted in the vertical direction by 1/3 pixel.

That is, on the screen 14, the blue liquid crystal plate 1
Pixel D B l- produced by a liquid crystal cell of 0.

Based on ~DBz-z, pixels DG + -+~DGz-z (
The D position is shifted upward by 1/3 pixel, and is a pixel D R+- generated by the liquid crystal cell of the liquid crystal plate 8 for red color.
+""D Rz-z is further shifted upward by 1/3 pixel.

In the configuration of FIG. 2, the image obtained on the screen 14 is a superimposition of red, green, and blue images vertically shifted by 1/3 pixel, and is therefore similar to that described above with respect to FIG. In this way, it is possible to obtain a visual effect as if the number of pixels in the vertical direction had increased by approximately three times.

Therefore, according to the configuration shown in FIG. 2, the same effect of image quality improvement as that obtained in the embodiment shown in FIG. 1 can be achieved on the screen 14.
It can be obtained in the vertical direction of the image displayed above.

FIG. 3 shows a third embodiment of the present invention, and in this embodiment, red, green, and blue images are shifted diagonally.

That is, based on the pixels D B + -r to DBz-t generated by the liquid crystal cells of the liquid crystal plate 10 for blue, the pixels DC, - generated by the liquid crystal cells of the liquid crystal plate 9 for green
, -DG2-2 are shifted by 1/3 pixels in the horizontal and vertical directions (that is, diagonally), and the pixels DR, , -DG2-2 are shifted by 1/3 pixels in the horizontal and vertical directions (that is, in the diagonal direction), and the pixels DR, , -DG2-2 are shifted by 1/3 pixels in the horizontal and vertical directions (that is, in the diagonal direction).
The position of DR2L2 is further shifted in the diagonal direction by 1/3 pixel.

Therefore, in the case of FIG. 3, as in the case of FIGS. 1 and 2, it is possible to obtain the same visual effect as if the number of upper pixels were tripled in the horizontal and vertical directions.

In addition, in the above-mentioned embodiment, the positions of the red and green images are made even by adjusting the position of the liquid crystal plate 8.9 relative to the blue image as a reference, but the present invention is not limited to this. In short, it is sufficient to relatively adjust the positions of the liquid crystal plates 9, 10, and 11.

In addition, instead of adjusting the positions of the liquid crystal plates 8, 9, and 10, for example, reflecting mirrors 5 placed on the optical path before and after each liquid crystal plate may be used.
7 and dichroic mirrors 3, 4, 11, and 12, the image may be shifted by changing the position or inclination of the optical system.

Furthermore, in the above embodiment, the image on the screen 14 is shifted in the order of red, green, and blue.
The order of shifting is not limited to this, but the same effect can be obtained by shifting, for example, red-blue-green or blue-green-red.

Similarly, in this embodiment, the light rays in the red light range are first separated, and then the light rays in the green light range are separated, but the separation of light rays is not limited to this. For example, the light rays in the blue light range are first separated. After separation, it can be widely applied to various projectors that separate light beams in the green light range.

Furthermore, although a case has been described in which a reflective dichroic mirror is used to separate red, green, and blue light rays, instead of this, for example, a filter that transmits only light rays in a specific light range may be used.

In the embodiments shown in FIGS. 1 to 3, the case where the red, green, and blue images are sequentially shifted by 1/3 pixel has been described, but apparently increasing the number of pixels does not necessarily require shifting by 1/3 pixel. It is not necessary to shift by /3 pixels, and the same visual effect can be obtained by selecting values around this.

Also, from this, on the screen 14, red,
The adjustment work to shift the positions of the green and blue images is much easier than the conventional adjustment work for superimposing them, and as a result, the adjustment mechanism for position adjustment has a simple structure. Therefore, it is possible to obtain a projector with a simple structure as a whole.

H Effects of the Invention As described above, according to the present invention, it is possible to obtain the same visual effect as by increasing the apparent number of pixels by using a conventionally used liquid crystal panel, and thereby A color display projector that can display images with improved image quality more naturally and smoothly can be easily realized.

[Brief explanation of drawings]

FIG. 1 is a partially enlarged view showing an image obtained on a screen in a first embodiment of a projector according to the present invention, and FIG. 2 is a partially enlarged view showing an image obtained on a screen in a second embodiment of a projector according to the present invention. FIG. 3 is a partially enlarged view showing the image obtained on the screen in the third embodiment of the projector according to the present invention, and FIG. 4 is a linear cross-sectional view showing the overall configuration of the projector. FIG. 5 is a partially enlarged view showing an image obtained on a screen in a conventional projector. l... Condensing lens, 2... White light source,
3.4, l0111...Dichroic mirror, 5-7...Reflector, 8-10...Liquid crystal plate, 13...Field lens, 14.・・・
···screen.

Claims (1)

[Claims] By transmitting red, green, and blue light through red, green, and blue transmissive liquid crystal panels, red, green, and blue image light is formed, and by projecting the image light onto a screen. In the projector configured to obtain a color display image, the position of the red, green, and blue images formed by the red, green, and blue image lights may be sequentially and relatively shifted in the horizontal direction and/or the vertical direction. A projector that projects the red, green, and blue image light onto a screen.