Computer graphics processing and selective visual display system – Plural physical display element control system – Display elements arranged in matrix
Reexamination Certificate
1998-09-16
2001-04-10
Hjerpe, Richard (Department: 2674)
Computer graphics processing and selective visual display system
Plural physical display element control system
Display elements arranged in matrix
C345S090000, C345S096000
Reexamination Certificate
active
06215465
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a liquid crystal displaying apparatus for televisions, projectors and the like. Particularly, this invention relates to a displaying apparatus using an active matrix transmission- or reflection-type liquid crystal display device, and a method of displaying an image by the display device.
Recently, a color liquid crystal displaying apparatus has widely been used as a display for televisions, personal computers, projectors with a large screen for projecting moving pictures, and so on. Particularly, a transmission-type liquid crystal display device is applied to the televisions and personal computers. On the other hand, a reflection-type liquid crystal display device is applied to the projectors. The liquid crystal display devices are combined with a color filter to achieve a precise and distortion-free image.
Generally, the active matrix driving method is employed for a liquid crystal displaying apparatus as shown in FIG.
1
. The apparatus shown in
FIG. 1
includes a signal processor
1
, a digital-to-analog (D/A) converter
2
, an amplifier (AMP)
3
, an inverter
4
, an analog switch
5
, a switch controller
6
, an offset voltage applier
7
and a liquid crystal display device (LCD)
8
.
A video signal supplied to the apparatus is subjected to digital processing by the signal processor
1
and converted into an analog signal by the D/A converter
2
. The analog video signal is amplified by the amplifier
3
and inverted by the inverter
4
. Either the amplified signal “a” or inverted signal “b” is selected for each field period by the switch
5
under the control of the switch controller
6
. The selected signal “c” is clamped at a level by the offset voltage applier
7
and supplied to the liquid crystal display device
8
.
In the apparatus shown in
FIG. 1
, the amplifier
3
, inverter
4
, switch
5
and offset voltage applier
7
are constituted by complex analog circuitry. Particularly, the offset voltage applier
7
is constituted by a damper and a complex buffer with high input impedance.
Concerning symmetry in the non-inverted video signal “a” and the inverted signal “b” in
FIG. 1
, highly precise gain, frequency characteristic, phase characteristic, and an offset amount are required. Those requirements are however difficult to meet by the complex circuitry, and an unevenness often occurs in the characteristics of the liquid crystal displaying apparatuses.
Furthermore, transfer of a polyphase video signal requires signal processing circuitry for each phase signal. A vertical stripe pattern noise would occur if the polyphase signal exhibits uneven characteristics. This results in an image of extremely low quality.
Accordingly, the conventional apparatus requires highly precise circuit components for securing the display precision and quality of the image. And, the analog circuit components must be adjusted accurately. These requirements results in a high manufacturing cost.
Particularly, for high-vision, the liquid crystal displaying apparatus must process the polyphase signal of eight or more phases. This results in a bulk analog circuitry.
SUMMARY OF THE INVENTION
A purpose of the present invention is to provide a liquid crystal displaying apparatus to display an image of high quality with a simple circuit configuration and a method thereof.
The present invention provides a liquid crystal displaying apparatus comprising: a first converter to convert an input analog video signal into digital video data; an inverter to invert the digital video data to inverted digital video data; a first selector to selectively output the digital video data and the inverted digital video data at most for each specific period of time; a second converter to convert the selectively output digital video data and the inverted digital video data into a first and a second analog video signal; means for adjusting the first and second analog video signals at different first and second bias voltage levels, respectively; a second selector to selectively output the adjusted first and second analog video signals at most for each of the specific period of time; and a liquid crystal display device to display an image in response to the selectively output first and second analog video signals.
Furthermore, the present invention provides a liquid crystal image displaying apparatus for displaying an image carried by a polyphase video signal including the first to N-th phase video signals (N being an integer of two or more), the apparatus comprising: a converter to convert the first to N-th phase video signals into first to N-th digital video data, respectively; an inverter to invert each digital video data to inverted video data corresponding to each digital video data; a first selector to selectively output each digital video data and the inverted data corresponding to each digital video data for each specific period of time; a second converter to convert the selectively output each digital video data into first analog signals and the inverted video data corresponding to each digital video data into second analog video signals; means for adjusting the first and second analog video signals at different first and second bias voltage levels, respectively; a second selectors to selectively output the adjusted first and second analog video signals for each of the specific period of time; and a liquid crystal display device to display the image in response to the selectively output first and second analog video signals.
Furthermore, the present invention provides a method of supplying a video signal to a liquid crystal displaying apparatus, comprising the steps of: converting an input analog video signal into digital video data; inverting the digital video data to inverted digital video data; selectively outputting the digital video data and the inverted digital video data at most for each specific period of time; converting the selectively output digital video data and the inverted digital video data into a first and a second analog video signal; adjusting the first and second analog video signals at different first and second bias voltage levels, respectively; selectively outputting the adjusted first and second analog video signals at most for each of the specific period of time to the liquid crystal display device.
REFERENCES:
patent: 5844538 (1998-12-01), Shiraki et al.
patent: 5907314 (1999-05-01), Negishi et al.
Asakura Tsutou
Furuya Masato
Dinh Duc
Hjerpe Richard
Jacobson Price Holman & Stern PLLC
Victor Company of Japan Ltd.
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