JP2001203955A - Method and device for dual-screen display - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for displaying two pictures on a display screen without any deterioration in picture quality. SOLUTION: In dual-screen display mode, a selector switch 12 is controlled to select the signal from a reception device 11 for an output terminal O1 and an external video signal for an output terminal O2. Data of an effective picture of a video source outputted to the terminal O1 are put in a memory 13a in specific sampling cycles from the switch S1 and image data of 480 lines of the video source supplied to the terminal O2 are put in a 2nd memory 13b through a switch S2. A memory controller 16 reads image data out of the memories 13a and 13b in specific timing cycles and writes them in a given addresses of a field memory 15, sets readout addresses in such timing that one picture is composed of 768 scanning lines as many as those of a display device side, and displays images without changing the number of scanning lines of the inputted video source.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a television device, and more particularly to a liquid crystal display device that projects an image on a screen or the like using a liquid crystal as an optical modulation element.

[0002]

2. Description of the Related Art A liquid crystal projector that modulates light emitted from a halogen lamp or the like by a liquid crystal plate driven by a video signal and projects the transmitted light or reflected light on a screen or the like by an optical lens has become widespread. Such a liquid crystal projector has a feature that a large screen display image of, for example, about 40 inches or 50 inches can be displayed on a television apparatus using a cathode ray tube.

However, if the display image becomes large, the display image becomes rough unless the density of the pixels forming the image is increased, and the image quality appears to be rather deteriorated. For example, when an image signal of a normal NTSC system is projected on a display screen of 40 inches or more, when viewed near the screen, scanning lines are conspicuous, and the resolution appears to be reduced.

Therefore, in general, when the display screen becomes large, the number of scanning lines constituting one screen is increased to compensate for flicker and image roughness. In the processing of such an image signal, for example, as shown in FIG. 3, normally, a scanning line interpolation process of interpolating the scanning lines of the signal with respect to the number n of the scanning lines of the video screen p constituting one field is performed. This is achieved by increasing the number of scanning lines to N (n <N) on the screen Q. In addition, during the scanning line interpolation processing, the pixel density in the horizontal direction can be simultaneously increased by the interpolation processing to increase the number of pixels, and the aspect ratio can be changed.

[0005]

As described above, when the number of scanning lines is interpolated in order to project a single image for a large screen, the roughness of the screen can be reduced by the effect of the interpolation processing. However, in the case of a two-screen display mode in which two types of video sources are displayed in one screen as shown in FIG. 4, for example, interpolation processing of the respective scanning lines of the video source A and the video source B is performed. The image processing apparatus adjusts the aspect ratio and the like of each input video source and synthesizes them so that they are displayed on the same screen. In this case, although the number of scanning lines in each of the video screens A and B is increased by the interpolation process, since the video screens A and B are displayed in a reduced form on the screen, the effect of interpolating the scanning lines is lost. There is a problem that the image quality is degraded by the processing.

[0006]

SUMMARY OF THE INVENTION The display device of the present invention provides a display device and a two-screen display method which can solve the above-mentioned problems. In order to prevent the image quality from deteriorating when performing screen display, for example, a first signal processing unit that converts a first video source composed of n scanning lines into a digital signal and stores the digital signal, Second scan line
A second signal processing means for converting the video source into a digital signal and storing the digital signal, and a scanning chain line for converting the first and second video signals output from the first and second signal processing means to n While two screens are displayed in the book state, the scanning lines are N (N> N).
and a third signal processing means formed on the display screen described as n).

According to the present invention, since the conversion of the number of scanning lines n is not performed on the composite screen for both the signal of the first video source and the signal of the second video source, the deterioration of the image quality at the signal processing stage is prevented. Can be prevented. Therefore, particularly when performing two-screen display on a display device having a large screen, deterioration in image quality can be reduced.

[0008]

FIG. 1 is a block diagram showing an outline of a signal processing section of a liquid crystal projector when the present invention is applied. In this figure, reference numeral 11 denotes a receiving apparatus for selecting and demodulating a desired channel from a received signal of a parabolic antenna or a received signal of a television antenna, and includes, for example, a tuner and a demodulator. And the demodulated VH
When an F television signal, a BS broadcast signal, or a mouse decoder is provided, an HDTV broadcast signal or the like is supplied to a selection switch 12 constituted by a demultiplexer. A video signal VS1,
VS2 and VS3 are also supplied, and the video signal is a DVD playback signal, digital BS signal, VTR playback signal, or the like. An arbitrary video source is selected by selecting a display mode of the system controller 18, and two output signals are output. Output can be made to terminals O1 and O2.

In a two-screen display mode, a selection switch is controlled. When a BS broadcast is received by the receiving device 11, the signal is selected and output to an output terminal O1 and supplied from the outside. Video signal output terminal O
2 can be selected. When a two-screen display is performed, the data of the effective screen of the video source output to the output terminal O1 is fetched from the switch S1 into the memory 13a at a predetermined sampling cycle, and the video source supplied to the output terminal O2 also receives the effective screen. The minute data is read into the second memory 13b via the switch S2. In the case of normal one-screen display, the image source selected at the output terminal O1 is supplied to the scanning line interpolation processing unit 13c, and the image of the number of scanning lines n is converted into, for example, the image of the number of scanning lines N (n <N). It can be converted into a signal and supplied to the field memory 15. At this time, the aspect ratio of the display screen can be converted.

Reference numeral 14 denotes a timing generation circuit for generating write address data and / or read address data in the memories 13a and 13b. The timing generation circuit converts the digital data into digital signals at a predetermined sampling period and writes the image data into the memories line by line. . In this case, assuming that the number of scanning lines of the effective image screen is 480 by detecting the synchronization signal of the input video signal, each memory 13a, 1a
In 3b, 480 pieces of image data are stored. At the time of reading the data, by performing address control such that the time axis is read in a shortened manner, two screens can be displayed on one display screen as shown in FIG. The image data read from each of the memories 13a and 13b is then supplied to the field memory 15, and the write address signal and the read address signal of the field memory 15 are designated from the memory controller 16 in accordance with the display format. I have.

For example, as shown in FIG. 2, the first image data A stored in the memory 13a is read out by the memory controller 16 at a predetermined timing cycle and written into a predetermined address of the field memory 15 at the same time as the memory. By reading out the second image data B stored in the memory 13b at a predetermined timing and a predetermined cycle,
The signal (A + B) constituting the composite screen is recorded on the field memory 15. Then, by reading the data recorded in the field memory 15 in units of a predetermined one field, a video signal is output so as to be a display image of two screens as shown in FIG. 4, for example. Although the above-described signal processing is described as being configured by a plurality of circuits, such circuit functions are performed by an IC circuit and a one-chip DSP (digital signal processor) controlled by a built-in microcomputer. It can also be formed.

Image data read out from the field memory 15 corresponding to the number of scanning lines of the liquid crystal projector is
It is converted into an analog signal by a D / A converter (not shown) or converted into R, G, B video signals in the form of digital data and supplied to the drive circuit of the liquid crystal projector. Display can be performed.

In this case, if the number of scanning lines of the input video sources A and B to be displayed on two screens are both 480 standard television signals, for example, the scanning of a liquid crystal projector is performed without performing the interpolation of the scanning lines. The read address is set at a timing such that one screen is composed of 768 lines, which is the number of lines. Then, an image is displayed while the number of scanning lines of the input video source is kept as it is, and the problem that the image quality is reduced by the signal processing for interpolating the scanning lines can be solved.

For example, when the display screen of the liquid crystal projector is a display screen of the landscape television system (16: 9) and the number of scanning lines is 768, sampling is performed so that the image data in the horizontal direction becomes 1368. If the number of scanning lines on the effective screen is 480 when the video source read and input is a 4: 3 standard television signal, the display screen has (768-480) / 2 vertical lines. Scan lines in background color (gray or black)
By reading the data as follows, two screens having an aspect ratio of 4: 3 can be displayed without changing the number of scanning lines. In this case, since no interpolation processing is performed on the input screen having the two-screen configuration, it is possible to solve the problem that the image quality is reduced by the signal processing.

[0015]

As described above, according to the two-screen display method of the present invention, for example, when standard video sources are connected and displayed on one screen, the number of scanning lines of the original video source is output and displayed as it is. Therefore, it is possible to solve the problem that the image quality of the display image is deteriorated by the interpolation processing as in the related art. In particular, by applying the two-screen display method of the present invention to a liquid crystal projector that is a large display device,
There is an effect that two screens can be viewed simultaneously on one television.

[Brief description of the drawings]

FIG. 1 shows a block diagram of image processing applied to a two-screen display method of the present invention.

FIG. 2 is a waveform diagram for explaining writing and reading of two video signals.

FIG. 3 is an explanatory screen diagram when a scanning line is interpolated.

FIG. 4 shows a two-screen front screen.

[Description of Signs] 11 receiving device, 12 selection switch, 13a, 13b
Memory, 14 timing generation circuit, 15 field memory, 17 signal processing circuit

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) H04N 5/66

Claims (4)

[Claims] A first video signal having n scanning lines is converted into a digital signal and stored; a second video signal having n scanning lines is converted into a digital signal and stored; The stored first video signal and second video signal are read out so as to be connected in the horizontal direction on the screen and written in the field memory, and the image data written in the field memory is composed of N scanning lines. A two-screen display method, wherein two-screen video signals are synthesized and displayed by reading the data so that (n <N). 2. An image according to claim 1, wherein said first and second video signals have an aspect ratio of 4: 3 and said composite screen has an aspect ratio of 16: 9. Two-screen display method described 3. A first signal processing means for converting a first video source consisting of n scanning lines into a digital signal and storing it, and converting a second video source consisting of n scanning lines into a digital signal. A second signal processing means for storing and storing the first and second video signals output from the first and second signal processing means on two screens with n scanning chain lines; A display device comprising: a third signal processing unit that forms a display screen where the number of scanning lines is N (N> n). 4. The display device according to claim 3, wherein said display device is constituted by a projector that projects light transmitted through a liquid crystal plate.