Computer graphics processing and selective visual display system – Plural physical display element control system – Display elements arranged in matrix
Reexamination Certificate
1995-07-13
2003-04-08
Faile, Andrew (Department: 2711)
Computer graphics processing and selective visual display system
Plural physical display element control system
Display elements arranged in matrix
C345S090000, C345S100000, C345S103000, C348S446000, C348S448000, C348S793000, C348S453000
Reexamination Certificate
active
06545653
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method for displaying an image signal that is suited for such matrix type display devices in which pixels are arranged into a matrix form in lines and columns. The present invention further relates to a display device for magnifying and projecting onto a screen, an image that has been displayed on a small-size liquid crystal display device, to a display device to be used as a monitor for a video camera, and to a display device to be used as a light valve of the aforementioned various display devices.
2. Description of the Prior Art
LCDs (Liquid Crystal Displays) have been aggressively researched and developed because of their many features such as being light weight and having a small thickness. However, they have a few drawbacks including a difficulty in increasing their size into large screens. Therefore, in recent years, much attention has been rapidly and increasingly focused on projection type display devices which magnify and project an image displayed by a small LCD by means of a projection lens or the like to obtain a large-screen display image. A display device for magnifying and projecting onto a screen an image that has been displayed on a small-size liquid crystal display device (hereinafter, referred to as projection type display device) commercially available at present uses a twist nematic (hereinafter, referred to as TN) LCD that takes advantage of the rotary polarization characteristic of liquid crystals.
Active-matrix type LCDs have been advanced to higher densities and increased numbers of pixels so that they are utilized as data display use displays for personal computers and workstations, and also as audio-visual displays of the standard system (NTSC) and HDTV system. Further, as the active-matrix type LCD has been increased in the number of pixels, a demand has also grown for higher speeds of the operating clock of source drive (data line drive) ICs. As a result, source drive ICs of high-speed operating clocks are under development, while proposed are methods in which a plurality of source drive ICs are operated in parallel and source lines of plurally divided screen areas are driven at the same time.
Twisted nematic liquid crystal devices are known as one of such display devices. Thin film transistors as active elements are driven by a source driver IC and a gate driver IC. If necessary, a plurality of source driver ICs are used. However, at joints of adjacent source driver ICs there occurs brightness differences due to variations in components for signal processing, resulting in deterioration of the image quality. In order to solve the above problem, a correction circuit may be added for correcting the brightness differences, or the source driver ICs have digital inputs. However, such measures would involve increases in cost, circuit scale, and mounting area around the LCD panel.
Recently, high temperature polysilicon techniques and low temperature polysilicon techniques have been developed, and by using such techniques, the gate driver IC and the source driver ICs can be formed at the same time as the TFTs. An LCD panel involves high cost and difficulties to have a large-area display area, and it is put into practical use as display devices to be used as an image pickup monitor for video cameras (hereinafter, referred to as viewfinder) and the like. A common feature of LCD panels fabricated by the high-temperature polysilicon technique and the low-temperature polysilicon technique is that the gate driver IC and the source driver ICs can be formed on the same substrate as well as the TFTs simultaneously. Therefore, there is no need of mounting the gate driver IC and the source driver IC on the LCD panel after the LCD panel is fabricated. It is also unnecessary to additionally fabricate the source driver IC or the like. Thus, the cost of the LCD panel can be reduced.
However, there still remains a problem of low upper-limit operating speed of the source driver circuit and the like formed directly on the LCD panel. The range of operating frequency in which the source driver circuit and the like operate stably is generally from 1 to 3 MHz. This requires a shift register and the like in the source driver circuit to be provided in a multi-stage arrangement. If the operating frequency of the shift register is 2 MHz while the LCD panel needs to be operated at 40 MHz, then a frequency division by 40/2=20 is required. This means that the shift register needs to be provided in 20 lines. The larger the number of shift registers, the larger the area occupied by the shift registers and the larger the number of defects that occur in the fabricating process. Therefore, this is not favorable.
As described above, LCD panels fabricated by the polysilicon technique, particularly by the low-temperature polysilicon technique, have an advantage of high feasibility of low prices, thus promising as display monitors for future personal computers and workstations. On the contrary, they are difficult to realize higher-speed driving (higher data rate or wider band). Therefore, it is desirable that wideband (high data rate) progressive scanning image signals of personal computers, workstations, and the like, can be displayed onto a display such as matrix type LCD panels which is poor at high-speed scanning, as mentioned above, but has advantages of simplicity and a low price, without causing any deterioration of image quality.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a method for displaying image signals and a device therefor, which method and device can display wideband (high data rate) progressive scanning image signals onto a display which is poor at high-speed scanning, such as matrix type LCD panels, without causing any deterioration of image quality.
Another object of the present invention is to provide a projection type display apparatus or the like using the above-mentioned method and device.
In one aspect of the invention, first, odd-line signals are extracted from progressive scanning image signals in a first frame, and the extracted,signals are displayed onto odd lines in a display panel with a dot matrix. Subsequently, even-line signals are extracted from progressive scanning image signals in a second frame consecutive to the foregoing first frame, and the extracted signals are displayed onto even lines in the display panel. Thus, an image of one frame is displayed in the display panel in two frame periods. If one frame is provided each {fraction (1/60)} second, an image is displayed each {fraction (1/30)} second.
In a second aspect of the invention, first, odd-line signals are extracted from progressive scanning image signals in a first frame, and each of the extracted signals are displayed onto an odd line and an even, line adjacent to the odd line in the display panel at the same time. Thus, an odd-line signal is displayed along two adjacent lines. Subsequently, even-line signals are extracted from progressive scanning image signals in the second frame consecutive to the foregoing first frame, and each of the extracted signals are displayed onto an even line and an odd lines adjacent to the even line in the display panel at the same time. Thus, an odd-line signal is also displayed along two adjacent lines. Then, for example, first and second line signals are displayed in a second line in the display panel, and second and third line signals are displayed in a third line in the display panel. Thus, an image of one frame is displayed in the display panel in two frame periods.
In a third aspect of the invention, signals of odd-lines (2n−1) are extracted from progressive scanning image signals in a first frame, and pixels in lines (4n−3) of a display panel hold the image signals of a first polarity with, respect to a potential of a counter electrode in a display panel, while pixels in lines (4n−1) hold the image signals of a second polarity, where “n” denotes an integer and the first polarity is positive polarity or negative p
Muraji Tsutomu
Takahara Hiroshi
Matsushita Electric - Industrial Co., Ltd.
Srivastava Vivek
Wenderoth , Lind & Ponack, L.L.P.
LandOfFree
Method and device for displaying image signals and viewfinder does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and device for displaying image signals and viewfinder, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and device for displaying image signals and viewfinder will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3005933