Computer graphics processing and selective visual display system – Plural physical display element control system – Display elements arranged in matrix
Reexamination Certificate
2000-03-09
2003-04-08
Chow, Dennis-Doon (Department: 2675)
Computer graphics processing and selective visual display system
Plural physical display element control system
Display elements arranged in matrix
C345S103000, C345S698000
Reexamination Certificate
active
06545655
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a Liquid-Crystal Display (LCD) device and more particularly, to an LCD device of the active-matrix addressing type that are capable of simultaneously displaying a television (TV) image and a car navigation image on the same screen at unequal resolutions, and a driving method of the device.
2. Description of the Prior Art
In general, on-vehicle LCD devices are used for displaying a car navigation image or a TV image. The vertical resolution of the on-vehicle LCD devices is typically set as approximately 240 scanning lines, which is optimum for displaying TV images.
FIG. 1
schematically shows the configuration of a prior-art LCD module as an example of LCD devices of this sort.
The prior-art LCD module of
FIG. 1
comprises an LCD panel
310
, two horizontal drivers
301
and
302
serving as data drivers, and a vertical driver
305
serving as a scanning driver.
The LCD panel
310
has scanning lines
311
extending along the rows of a matrix and arranged along the columns thereof at equal intervals, and data lines
312
extending along the columns of the matrix and arranged along the rows thereof at equal intervals. The panel
310
further has display elements (not shown) located at the respective intersections P of the scanning and data lines
311
and
312
. The display elements constitute the respective pixels of the LCD device and therefore, these pixels are arranged in the matrix array. Each of the pixels arranged along any one of the data lines
312
corresponds to each of the rows of the matrix. Each of the pixels corresponding to the rows of the matrix is selected by scanning signals supplied through the scanning lines
311
and are driven by data signals supplied through the data lines
312
.
The horizontal driver
301
receives a horizontal start signal HST, a horizontally-shifting clock signal HCK, and a video data signal VD. The driver
301
drives the pixels located on the left-hand side with respect to the panel
310
in FIG.
1
.
The horizontal driver
302
receives the video data signal VD. Also, the driver
302
receives a horizontal start signal HST′ and a horizontally-shifting clock signal HCK′ supplied from the driver
301
. The signal HST′ has a specific temporal delay with respect to the horizontal start signal HST. Similarly, the signal HCK′ has a specific temporal delay with respect to the horizontally-shifting clock signal HCK. The driver
302
drives the pixels located on the right-hand side with respect to the panel
310
in FIG.
1
.
The vertical driver
305
receives a vertical start signal VST and a vertically-shifting clock signal VCK.
The panel
310
is driven by the horizontal drivers
301
and
302
, which is due to the fact that the total number of the data lines
312
is greater than the output terminals of each of the drivers
301
and
302
.
In recent years, there has been a tendency that the amount of information contained in the navigation images increases according to the ongoing functional expansion of car navigation systems. Under such tendency, there has been the growing need to enlarge the screen size and to raise the resolution in the on-vehicle LCD devices. Furthermore, there has been the need to make it possible to display different images on the two horizontally-divided display areas of the screen, which is termed the “dual-image displaying function”.
It is comparatively easy to display two different images on the horizontally-divided display areas of the screen at an equal vertical resolution. For example, it can be realized by applying different video data VD to the horizontal drivers
301
and
302
in the module of FIG.
1
.
However, it is not easy to display two different images on the horizontally-divided display areas of the screen at unequal vertical resolutions. For example, it is not easy to display a high-resolution navigation image and a normal-resolution TV image on the divided display areas. This is because the displayable resolution is determined by a lower one of the resolutions. As a result, there arises a problem that the resolution of the navigation image is degraded.
On the other hand, to realize high-quality images, there has been known a technique that an interlace signal is converted to a non-interlace signal by double-scanning conversion and then, the non-interlace signal thus produced is used for displaying high-quality images. This is termed the “double-scanning technique”. If this technique is used, the vertical resolution can be improved.
A prior-art LCD device of this sort is disclosed in the Japanese Non-Examined Patent Publication No. 5-64108 published in December 1993. The LCD panel of this prior-art device is comprised of an odd-numbered row data driver for driving the pixels in the odd-numbered rows of the matrix, an odd-numbered row scanning driver for scanning the same pixels, an even-numbered row data driver for driving the pixels in the even-numbered rows of the matrix, and an odd-numbered row scanning driver for scanning the same pixels. These four drivers are operable independently. Each of the odd- and even-numbered row data drivers receives alternately an actual signal generated by a double-scanning converter circuit and an interpolating signal at each vertical scanning period (1V). Each of the odd- and even-numbered row scanning drivers drives simultaneously the pixels in the odd-numbered or even-numbered rows.
Thus, the prior-art LCD device disclosed in the Publication No. 5-64108 provides high-quality TV images without raising the operating frequency of the data and scanning drivers.
Another prior-art LCD device of this sort is disclosed in the Japanese Non-Examined Patent Publication No. 10-62811 published in March 1998. The LCD panel of this device is comprised of a first plurality of scanning lines and a second plurality of scanning lines, and a first plurality of data lines and a second plurality of data lines. The first plurality of scanning lines are driven by a scanning driver and the second plurality of scanning lines are driven by another scanning driver. The first plurality of data lines are connected to the pixels in the odd-numbered rows of a matrix. The second plurality of data lines are connected to the pixels in the even-numbered rows of the same matrix. The first plurality of scanning lines receive writing or resetting pulses. The second plurality of scanning lines receive writing or resetting pulses. The first and second pluralities of scanning lines are simultaneously driven by their corresponding scanning drivers. The pixels in the odd-numbered rows receive one of the writing and resetting pulses and at the same time, those in the even-numbered rows of the same matrix receive the other.
Thus, the prior-art LCD device disclosed in the Publication No. 10-62811 improves the contrast while the driving voltage is kept low, thereby providing high-quality images.
However, the prior-art LCD devices disclosed in the Publication Nos. 5-64108 and 10-62811 were developed in order to improve the quality of image displayed as a single image on the screen. As a result, similar to the prior-art LCD module shown in
FIG. 1
, it is difficult for these prior-art LCD devices to display two different images on the horizontally-divided display areas of the screen at unequal vertical resolutions.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide an LCD device and its driving method that make it possible to simultaneously display two images on a screen at unequal resolutions.
Another object of the present invention is to provide an LCD device and its driving method that make it possible to simultaneously display a high-resolution car navigation image and a normal-resolution TV image on a screen.
The above objects together with others not specifically mentioned will become clear to those skilled in the art from the following description.
According to a first aspect of the present invention, an LCD device is provided, which is comprised of:
(a)
Chow Dennis-Doon
Foley & Lardner
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