Computer graphics processing and selective visual display system – Display driving control circuitry – Display power source
Reexamination Certificate
2001-08-29
2004-02-10
Chow, Dennis-Doon (Department: 2675)
Computer graphics processing and selective visual display system
Display driving control circuitry
Display power source
C345S087000, C345S095000, C345S098000
Reexamination Certificate
active
06690367
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an image display panel and an image viewer of an image display apparatus which uses liquid crystals or organic light-emitting diodes and which can be manufactured at low cost.
The conventional art will be described hereafter with reference to FIG.
7
.
FIG. 7
is a schematic diagram of an image display panel
150
using, for example, a low-temperature polycrystalline Si-TFT liquid crystal in accordance with a conventional example. In an image region
105
, pixels
100
each having a liquid crystal capacitance
102
and a pixel switch
101
constituted by a low-temperature polycrystalline Si-TFT are arranged in matrix form, and the gate of the pixel switch
101
is connected to a gate-line shift register
106
via a gate line
103
. In addition, the drain of the pixel switch
101
is connected to a D/A converter
107
via a signal line
104
. An output signal from a latch circuit
108
is inputted to the D/A converter
107
, and an output signal from a horizontal shift register
109
is inputted to the latch circuit
108
. Signals from a gate-line shift register input terminal
121
, a latch circuit input terminal
122
, and a horizontal shift register input terminal
123
are inputted to the gate-line shift register
106
, the latch circuit
108
, and the horixontal shift register
109
via level shift circuits
111
, respectively. In addition, high voltages supplied from a high-voltage input terminal
124
are applied to the respective level shift circuits
111
. The level shift circuits
111
are circuits for boosting a low-voltage signal of, for example, 5 V or less inputted to the input terminals
121
to
123
to a high voltage of, for example, 13 V necessary for the operation of the registers
106
and
109
and the latch circuit
108
. In addition, a signal line from an image signal data input terminal
125
is connected to the latch circuit
108
. The aforementioned elements are configured on an insulating substrate such as a glass substrate. It should be noted that a description will be omitted here of general arrangements necessary for an image display apparatus other than the image display panel
150
, such as color filters, peripheral drive circuits, and the like.
Hereafter, a description will be given of the operation of the above-described conventional example. A horizontal shift signal, inputted from the horizontal shift register input terminal
123
and converted by the level shift circuit
111
to a high-voltage amplitude signal corresponding to a high voltage supplied from the high-voltage input terminal
124
, drives the horizontal shift register
109
. The horizontal shift register
109
drives the latch circuit
108
at a predetermined timing so as to allow a first latch circuit in the latch circuit
108
to consecutively latch image signals inputted from the image signal data input terminal
125
. When the image signals corresponding to the number of pixels of one horizontal line are latched by the first latch circuit in the latch circuit
108
, a latch signal inputted from the latch circuit input terminal
122
and converted to a high-voltage amplitude signal by the level shift circuit
111
is inputted to the latch circuit
108
so as to allow the image signals in the aforementioned first latch circuit to be latched by a second latch circuit in the latch circuit
108
. Subsequently, the image signals corresponding to the number of pixels of one horizontal line and latched by the second latch circuit are inputted in parallel to the D/A converter
107
and subjected to digital-to-analog conversion, and analog image signal voltages are outputted to the signal line
104
. At this time, a gate line drive signal inputted from the gate-line shift register input terminal
121
and converted to a high-voltage amplitude signal by the level shift circuit
111
drives the gate-line shift register
106
at a predetermined timing so as to turn on the pixel switches
101
of the pixels of a predetermined row through the gate line
103
. As a result, the analog image signal voltages outputted to the signal line
104
is written in the liquid crystal capacitances
102
of the pixels of the predetermined row. The liquid crystal capacitances
102
are respectively provided with counter electrodes, thereby making it possible to display an image corresponding to analog image signal voltages which are applied to the liquid crystals of the respective pixels
100
.
It should be noted that, concerning the above-described conventional art, a detailed description is given in, for example, ISSCC 2000, Digest of Technical Papers, pp. 188-189.
SUMMARY OF THE INVENTION
According to the above-described conventional art, by providing the level shift circuits
111
on the insulating substrate, signals which are inputted to the respective terminals of the gate-line shift register input terminal
121
, the latch circuit input terminal
122
, the horizontal shift register input terminal
123
, and the image signal data input terminal
125
can be set to low-voltage amplitude signals of 5 V or thereabouts.
However, with the above-described conventional art, it has been impossible to configure all the circuits for driving the image display panel
150
by only low-voltage circuits of 5 V or less which can be coped with by a general LSI. The reason for this is that to apply a high voltage of 13 V to the level shift circuits
111
, it is necessary to supply a high voltage of 13 V to the high-voltage input terminal
124
from an external circuit, so that it has been inevitable to provide a high-voltage power supply circuit in a peripheral device which is different from the image display panel
150
and which is provided in the image display apparatus to drive the image display panel
150
. Since a high-withstand-voltage component other than a general LSI needs to be adopted for this high-voltage power supply circuit, it is difficult to configure the entire above-mentioned peripheral device by a general low-withstand-voltage LSI, which has resulted in an increase of the manufacturing cost of the image display apparatus.
An object of the present invention is to lower the cost of the image display apparatus by realizing all the circuits such as drive circuits and the like in the peripheral device by a general LSI having a low withstand voltage of 5 V or less.
The following means is adopted in the present invention to overcome the above-described problem.
An image display panel comprising an image region
105
in which pixels are arranged in matrix form, a gate-line shift register
106
, a D/a converter
107
, a latch circuit
108
, a horixontal shift register
109
, and a plurality of level shift circuits
111
, wherein signals are inputted to said shift registers
106
,
109
and said latch circuit
108
from a gate-line shift register input terminal
121
, a latch circuit input terminal
122
, and a horizontal shift register input terminal
123
through said level shift circuits
111
, respectively, and a signal from an image signal data input terminal
125
is inputted to said latch circuit
108
, all the elements mentioned being configured on an insulating substrate, characterized in that a high-voltage generating circuit
212
including a capacitance and a diode is provided on said insulating substrate, and that clocks having an amplitude of a low voltage and a predetermined frequency are inputted to said high-voltage generating circuit
212
from said high-voltage-generating-circuit input terminals
213
,
214
, while a low constant voltage is inputted to said high-voltage generating circuit
212
from a constant-voltage input terminal
215
, so as to supply a high voltage to each of said level shift circuits
111
from an output terminal
216
of said high-voltage generating circuit
212
.
REFERENCES:
patent: 4384287 (1983-05-01), Sakuma
patent: 5426447 (1995-06-01), Lee
patent: 5995072 (1999-11-01), Nakajima
Antonelli Terry Stout & Kraus LLP
Chow Dennis-Doon
Hitachi , Ltd.
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