Computer graphics processing and selective visual display system – Plural physical display element control system – Display elements arranged in matrix
Reexamination Certificate
1999-10-07
2003-02-18
Mengistu, Amare (Department: 2673)
Computer graphics processing and selective visual display system
Plural physical display element control system
Display elements arranged in matrix
C345S094000
Reexamination Certificate
active
06522319
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an electrooptical apparatus having a function causing a part of a display screen to be in a display state and causing the other to be in a non-display state and a driving method therefor. Furthermore, the invention, using a liquid crystal display apparatus as the electrooptical apparatus, relates to the driving method for the liquid crystal display apparatus, which allows a partial display state without providing an incompatibility and with less power consumption, and it also relates to the liquid crystal display apparatus performing display operation according to the above. The present invention also relates to a driving circuit suitable for driving the electrooptical apparatus of the invention.
Furthermore, this invention relates to an electronic equipment to be used for the electrooptical apparatus and the display apparatus described above.
2. Description of Related Art
With display apparatuses being used for portable electronic equipments such as portable telephones, the number of display dots is increasing year by year so that increasing amounts of information can be displayed. Accordingly, power consumption by the display apparatus is also increasing. Generally, the portable type electronic equipment uses battery as a power source; therefore, reduced power consumption with the display apparatus is strongly demanded so that battery service life can be extended. That is why, a study has begun for development such that with a display apparatus having a larger number of the display dots, a full screen is displayed when it is necessary; however, in normal use, only a partial region of a display panel is allowed to be in a display state and the other is left in a non-display state so that power consumption can be reduced. Furthermore, in response to the demand for power-consumption reduction, as display apparatuses of portable type electronic equipment, liquid crystal display panels of a reflective type or a transflective type designed by placing importance on appearance in a reflection mode is used.
In conventional liquid crystal display apparatuses, they have, in most cases, a function allowing control of display
on-display operations on a full-screen basis; however, a display apparatus having a function that allows only part of a full screen to be in a display state and allows the other to be in a non-display state has not been realized to date. A method to realize a function that allows only partial lines of a liquid crystal display panel to be in a display state and the other to be in a non-display state has been proposed with Japanese Unexamined Patent Publication Nos. 6-95621 and 7-281632. Both of these two proposals disclose a method in which display duties are varied according to the case of a partial display and the case of a full-screen display so as to obtain driving voltages and bias ratios which are suitable to the individual duties.
The method proposed in Japanese Unexamined Patent Publication No. 6-95621 will be described below with reference to
FIGS. 19
to
21
.
FIG. 19
is a block diagram showing an example of conventional liquid crystal display apparatuses. A block
51
represents a liquid crystal display panel (LCD panel) in which a substrate on which plural scanning electrodes are formed and a substrate on which plural signal electrodes are formed are arranged to oppose each other with a several-&mgr;m gap, and a liquid crystal is enclosed in the gap. By the liquid crystal at cross sections of the scanning electrodes arranged in the line direction and the signal electrodes arranged in the column direction, pixels (dots) are to be formed in a matrix. A block
52
represents a scanning-electrode driving circuit (Y driver) that drives the scanning electrodes, and a block
53
represents a signal-electrode driving circuit (X driver) that drives the signal electrodes. Plural voltage levels necessary for driving the liquid crystal are formed in a driving-voltage forming circuit represented by a block
54
and are applied to the liquid crystal display panel
51
through the X driver
53
and the Y driver
52
. A block
57
represents a scanning control circuit that controls the number of the scanning electrodes to be scanned. A block
55
represents a controller that supplies signals necessary for these circuits, FRM denotes a frame start signal, CLY denotes a scanning-signal transfer clock, CLX denotes a data transfer clock, Data denotes display data, LP denotes a data latch signal, and PD denotes a partial display control signal. A block
56
represents a power source for the circuits described above.
In this conventional example, a case in which the partial display appears on the left-half screen and on the upper-half screen is described; however, hereinbelow, a description will be given of the latter case in which lines for the upper-half screen are arranged in the display state and lines for the lower-half are arranged in the non-display state. The number of the scanning electrodes is assumed to be 400. The controller
55
turns the partial display control signal PD to an H level to allow the lower-half screen to be in the display state. When the partial display control signal PD is at an L level, all the scanning electrodes are scanned at a 1/400 duty, by which the full-screen is turned to the display state. When the partial display control signal PD is at the H level, only the scanning electrodes for the upper-half screen are scanned at a 1/200 duty, by which the upper-half screen is turned to the display state and the remaining lower-half screen is turned to the non-display state. Switching to the 1/200 duty is performed by switching to the duplicated cycle of the scanning-signal transfer clock CLY to reduce the number of clocks in one frame period. A scanning-stopping manner for the scanning electrodes for the lower-half screen in the partial display state is not described in detail. From the internal circuit diagram of the scanning control circuit block
57
, however, the manner is considered to be such that as follows. That is, when the control signal PD is turned to the H level, data to be transferred from the 200th stage to the 201st stage of a shift register in the Y driver is fixed at the L level, resulting in that outputs of the 201st to the 400th from the Y driver, which are fed to the scanning electrodes of the 200th to the 400th, are maintained at a non-selection voltage level.
FIG. 20
shows an example of driving voltage waveforms indicating a horizontal line at every other scanning-electrode line in the partial display state of this conventional example. A represents waveforms of voltages applied to one pixel on the upper-half screen, and B represents waveforms of voltages applied to all the pixels on the lower-half screen. In the figure, bold lines in the waveforms A and B indicate scanning electrode driving waveforms, and thin lines indicate signal electrode driving waveforms.
A selection signal V
0
(or V
5
) is sequentially applied to each line of the scanning electrodes for the upper-half screen in every selection period (one horizontal scanning period: 1 H), and a non-selection voltage V
4
(or V
1
) is applied to other lines of the scanning electrodes. ON/OFF information regarding individual pixels on selected lines is sequentially applied to the signal electrodes synchronously with the horizontal scanning period. More particularly, in a period when application voltages for selected lines of the scanning electrodes are V
0
, V
5
is applied to the signal electrodes of ON-pixels on selected lines and V
3
is applied to the signal electrodes of OFF-pixels; in a period when application voltages are V
5
, V
0
is applied to the signal electrodes of ON-pixels, and V
2
is applied to the signal electrodes of OFF-pixels. The voltage applied to the liquid crystal for individual pixels is the differential voltage between the scanning voltage applied to the scanning electrode (the selection voltage and the non-selection voltage) and the signal voltage app
Mengistu Amare
Oliff & Berridg,e PLC
LandOfFree
Electro-optical device and method for driving the same,... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Electro-optical device and method for driving the same,..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Electro-optical device and method for driving the same,... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3123106