JPH04366828A - Projection image display device - Google Patents

Abstract

PURPOSE:To prevent the sticking of a CRT fluorescent surface and the deterioration of a liquid crystal display panel, etc., by displaying an image on the entire surface of a screen while properly converting its original aspect ratio, and projecting the image by an optical means so that the original aspect ratio is obtained. CONSTITUTION:An image display means 3 and a video output means 5 display the image with its original aspect ratio and also displays it over the entire surface of the screen while converting the image into an image having the same aspect ratio with the screen. The optical means 4 projects the image having the same aspect ratio with the display screen 2 and also projects the image with its original aspect ratio on the screen 2. A projection light shield means 6 cuts off the projection light of a blank part 7 where the image is not displayed originally to display the projection image with a clear contour. Consequently, even when an image which is different in aspect ratio from the screen characteristic to the device is displayed for a long time, the entire surface of the screen of the display means 3 is used for the display at all times and no partial deterioration is caused.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection type image display device capable of displaying images having different aspect ratios between a display screen and a screen.

0002

2. Description of the Related Art Image display devices used in conventional television receivers and the like have a screen with a standard aspect ratio of 3:4. In recent years, in order to display high-definition, realistic images, image display devices have appeared that have screens that are wider than standard screens (for example, a wide aspect ratio of 9:16). Along with this, there are increasing opportunities to display a standard aspect ratio video on a wide aspect ratio screen, or, conversely, to display a wide aspect ratio video on a standard aspect ratio screen. When displaying an image having an aspect ratio different from that of the screen unique to the image display device as described above, it is common for blank areas where no image is displayed to appear at the top and bottom or left and right of the screen. If this display continues for a long time,
For example, between the part where the video is displayed and the blank part,
The degree of deterioration such as burn-in of the fluorescent surface of the cathode ray tube (CRT) and fading of the color filter of the liquid crystal display panel varies.
This causes uneven brightness and color when displaying the entire screen.

An example of a conventional solution to this problem is shown in FIG.
Shown below. FIG. 5(a) is disclosed in Japanese Unexamined Patent Publication No. 2-179085, in which a movable panel 11 provided in front of a screen 10 is opened and closed according to the aspect ratio of the image to be displayed, and a blank area where no image is displayed is shown. This is a conventional example configured to shield the Moreover, FIG. 5(b) is
It was disclosed in the publication No. 233078, and the screen 1
This is a conventional example in which a polarizing plate made of liquid crystal or the like is provided on the front surface of 0 to form an optical shielding portion 12. These conventional solutions are characterized by displaying an appropriate pseudo image in a blank area where no video is normally displayed, and shielding the pseudo image from the front side of the screen so that it cannot be seen.

0004

[Problems to be Solved by the Invention] In the conventional solutions as described above, the shielding means is exposed from the front side of the screen, causing discomfort to the viewer, or the screen is covered with a polarizing plate. In addition to creating a new problem of reduced screen brightness, in order to even out the deterioration of the screen, which is the original problem, it is necessary to display a suitable pseudo image in the blank area where no image is displayed and then cover it up. You have to make unnecessary displays.

An object of the present invention is to improve the reduction in device life caused by burn-in on the fluorescent surface of a CRT and deterioration of the liquid crystal display panel, even when displaying images with a different aspect ratio from the screen unique to the image display device for a long time. To provide a projection type image display device capable of displaying images that do not cause discomfort to viewers.

[0006]

[Means for Solving the Problems] In order to achieve the above object, the projection type image display device of the present invention uses an image display means using a CRT or a liquid crystal display panel, etc., and converts the original aspect ratio of the image to produce an image. An image output means capable of displaying an image on the entire screen of the display means, and an optical means capable of projecting an image at the original aspect ratio on the display screen, and the optical means and the display screen are connected together. A means for blocking part of the projected light is provided between the two.

[0007]

[Operation] The image display means and the video output means not only display the video with its original aspect ratio, but also convert it into a video with the same aspect ratio as the screen of the image display means and display it on the entire screen. The optical means can project an image with the same aspect ratio as the display screen, and also functions to project an image with the original aspect ratio on the display screen. The means for blocking the projection light functions to block the projection light in the blank area where no image is originally displayed, so that the outline of the projected image is clearly displayed. Due to these functions, even when displaying a video having a different aspect ratio from the screen unique to the image display device for a long time, the entire screen of the image display means is always used for display, and no partial deterioration occurs.

[0008]

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows the basic configuration of a rear projection type image display device which is an embodiment of the present invention. A screen 2 is provided on one side of the cabinet 1 to project a wide aspect ratio image from inside. Inside the screen 2, movable shielding means 6 for shielding a part of the projection light are arranged on both sides of the screen 2. Inside cabinet 1, there is a projection type CR with the same aspect ratio as screen 2.
T3 and optical means 4 for projecting the image displayed on the projection type CRT 3 onto the screen 2 are provided. Further, a video output circuit 5 for driving the projection type CRT 3 and other electric circuit means are provided. In the embodiment shown in FIG. 1, three projection type CRTs are actually used to display the three primary colors of red, green, and blue, but one of them is shown in the figure for simplicity.

In FIG. 1, the video output circuit 5 has the function of converting the original aspect ratio of the video to the same aspect ratio as the screen of the projection CRT 3 and displaying it on the entire screen of the projection CRT 3. Further, the optical means 4 includes a video output circuit 5
It has a function of converting the aspect ratio and projecting the image displayed on the projection type CRT 3 onto the screen 2 so that it has the original aspect ratio of the image. The projection light shielding means 6 is
When displaying an image having a different aspect ratio from that of the screen 2, blank parts 7 that occur on the left and right sides of the screen are blocked, and the outline of the projected image is clearly displayed. By using these functions in combination, an image having a different aspect ratio from that of the screen 2 can be displayed on a portion of the screen 2.

FIG. 2 shows an example of image display in the embodiment shown in FIG. Figure 2(a) shows a display method when the image to be displayed has the same aspect ratio as screen 2, in which a wide aspect ratio image is displayed on the entire screen 8 of the projection type CRT, and screen 2 is projects the image of the projection type CRT with the same aspect ratio. Figure 2(b) shows the case where the aspect ratio of the video to be displayed is smaller than that of screen 2 (
For example, an example of a method for displaying a standard aspect ratio video is shown. On the screen 8 of the projection CRT, the original aspect ratio of the image is converted to an image with the same aspect ratio as the screen 2, and the image is displayed on the entire screen, and the image is projected onto the screen 2 so that the image has the original aspect ratio. . At this time, the projection light shielding means 6 is moved in accordance with the aspect ratio of the image to be displayed to shield the projection light from the outline of the projected image. FIG. 2C shows another method when the aspect ratio of the video to be displayed is smaller than that of the screen 2. On the screen 8 of the projection type CRT, the image is displayed with its original aspect ratio as it is, and furthermore, appropriate pseudo images 9 are displayed in the blank areas appearing on the left and right sides of the image. The image of the projection type CRT is projected onto the screen 2 with the same aspect ratio, and the projection light of the portion where the pseudo image 9 is displayed is blocked by the blocking means 6.

As described above, in the embodiment shown in FIG. 1, even when an image with a smaller aspect ratio is displayed for a long time on the wide aspect ratio screen peculiar to the image display device, the screen of the projection type CRT is always made to emit light. CRT
The deterioration of the fluorescent surface becomes uniform. In particular, since the projection light shielding means is provided inside the cabinet, an image with clear outlines can be displayed without making the viewer aware of the existence of the shielding means. In addition, when displaying by converting the screen aspect ratio, the luminescent image displayed on the entire screen of the projection CRT is reduced and projected onto the screen and focused, so the screen brightness of the projection CRT is reduced. It is possible to display higher brightness than usual without particularly increasing the brightness. That is, even if the screen brightness of the projection type CRT is slightly lowered, the image can be displayed at normal brightness, so there is an advantage that deterioration of the fluorescent surface can be alleviated. Although FIG. 1 shows an embodiment in which, for example, a standard aspect ratio image is displayed on a wide aspect ratio screen, the present invention can also be implemented in a rear projection type image display device having a standard aspect ratio screen. The point is the same when doing so.

Next, a method for switching image display in one embodiment of the present invention will be explained using FIGS. 3 and 4.

FIG. 3 is a cross-sectional view showing the configuration of a rear projection type image display device which is an embodiment of the present invention. A projection type CRT 3, a projection lens 40, a lens slide 41, a reduction projection lens 42, mirrors 43 and 44, a projection light shielding means 6, etc. are arranged inside a cabinet 1 provided with a screen 2 having a wide aspect ratio. In particular, the reduction projection lens 42 is made movable via the lens slide 41. This reduction projection lens 42 functions to reduce the aspect ratio of the image displayed on the screen of the projection type CRT 3 and project it onto the screen 2. That is, when displaying a wide aspect ratio image in this embodiment, the reduction projection lens 42 is moved and the image displayed on the projection CRT 3 is projected onto the screen 2 using only the projection lens 40 and mirrors 43 and 44. Project. On the other hand, when displaying an image whose aspect ratio differs from that of the screen, the aspect ratio is converted, the image is displayed on the entire screen of the projection type CRT 3, and is projected using both the projection lens 40 and the reduction projection lens 42. As a result, an image with the original aspect ratio is displayed on the screen 2.

In this way, the embodiment shown in FIG. 3 shows a method in which a part of the projection lens system is made movable and used by moving it according to the aspect ratio of the image to be displayed. It is also possible to prepare a plurality of types of lenses and projection lenses dedicated to images with different aspect ratios, and to switch between them for use. The same effect can also be obtained by using, for example, a concave mirror as a reflection mirror for the projection light so that the projection light is projected onto the screen at the original aspect ratio.

FIG. 4 is an image display control system diagram in the embodiment of FIG. The video signal input to the terminal 50 passes through the detection circuit 51 and enters the video output circuit 5. Detection circuit 51
Then, the video system of the video signal (for example, the current television system, etc.) is detected, and a control signal indicating the image aspect ratio, number of scanning lines, etc. is generated. This control signal is sent to the video output circuit 5, the lens drive section 52, and the projection light shielding means 6. The video output circuit 5 processes the video signal based on the control signal from the detection circuit 51 and generates a drive signal for the projection CRT 3. In particular, when a video signal with a different screen aspect ratio is input, the video signal is processed so that the image is displayed on the entire screen of the projection type CRT 3, and a drive signal is generated based on the video signal. The lens drive unit 52 moves the reduction projection lens 42 based on the control signal from the detection circuit 51. Further, the projection light shielding means 6 is opened and closed by a control signal from the detection circuit 51, and the left and right outlines of the displayed image are clearly projected.

As described above, in the embodiment shown in FIG. 3, when an image with a smaller aspect ratio is displayed on the wide aspect ratio screen unique to the image display device, the image display can be automatically switched. . This switch is
Of course, it is also possible to do it manually. As a result, even when displaying images with different aspect ratios, the images can be displayed without causing the viewer to experience any troublesome operations.

As described above, regarding the embodiments of the present invention, the projection type CR
Although an example of a rear projection type using a T is shown, a liquid crystal display panel or other display device may be used instead of a projection type CRT. In particular, using a thin display device such as a liquid crystal display panel is advantageous in reducing the depth of the device. Furthermore, when applied to a front projection type image display device that projects an image from the front side of a display screen, the same principle can be applied.

[0019]

Effects of the Invention According to the present invention, even when displaying an image having a different aspect ratio from the screen unique to the image display device for a long period of time, burn-in of the fluorescent surface of the CRT used as the image display means and deterioration of the liquid crystal display panel can be prevented. In addition, it is possible to display an image that does not cause discomfort to the viewer. In particular, since images with sufficient brightness can be displayed even if the screen brightness of the image display means is lowered, the life of the device can be further improved.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the basic configuration of a rear projection type image display device that is an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an example of image display in the embodiment of FIG. 1;

FIG. 3 is a sectional view showing the configuration of a rear projection type image display device that is an embodiment of the present invention.

FIG. 4 is a block diagram of image display control in the embodiment of FIG. 3;

FIG. 5 is an explanatory diagram showing an example of a conventional solution.

[Explanation of symbols]

1...cabinet, 2...screen, 3...projection type CRT
, 4... Projection optical system, 5... Video output circuit, 6... Shielding means,
7...Blank part of the image.

Claims (5)

[Claims] Claims: 1. A projection type image display device comprising an image display means and an optical means for projecting an image onto a display screen, wherein an image having a different aspect ratio between the display screen and the screen is converted to the aspect ratio of the screen and displayed. What is claimed is: 1. A projection type image display device comprising: a display means for displaying images, and an optical means for projecting images in the form of a display spectrum. 2. The projection type image display device according to claim 1, further comprising means for blocking a part of projection light between the display screen and the optical means as the display means. 3. The projection type image display device according to claim 2, further comprising means for detecting an aspect ratio of an image to be displayed and blocking a part of the projection light as the shielding means. 4. In claim 1, the display means includes:
A projection type image display device that includes a display screen with a wide aspect ratio, a means for expanding an image having a smaller aspect ratio than the display screen in the horizontal direction of the screen, and a reduction in the horizontal direction by the optical means. 5. An image having a different aspect ratio from the display screen to the screen is displayed on a part of the screen of the image display means, and an arbitrary image is added to the blank part of the image that occurs in the remaining part of the screen. 1. A projection type image display device configured to project onto a display screen, and comprising means for blocking projection light of an image in the blank area on the back side of the display screen.