Computer graphics processing and selective visual display system – Plural physical display element control system – Display elements arranged in matrix
Reexamination Certificate
1999-01-25
2001-08-28
Shalwala, Bipin (Department: 2673)
Computer graphics processing and selective visual display system
Plural physical display element control system
Display elements arranged in matrix
C385S129000, C310S328000
Reexamination Certificate
active
06281868
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a display apparatus of small electric energy consumption and high raster luminance, and more particularly to a display apparatus which controls the displacement of actuators in directions into and out of contact with a light guide plate depending on an attribute of an image signal that is inputted, to control leakage light in given areas of the light guide plate for thereby displaying an image depending on the image signal on the light guide plate.
BACKGROUND ART
There have heretofore been known display apparatus including cathode-ray tubes (CRT), liquid crystal display panels, plasma display panels, etc.
Cathode-ray tubes include ordinary television receivers and monitors for use with computers. While the cathode-ray tubes can produce bright rasters, they consume large electric energy and have a depth that increases in proportion to the raster size. The cathode-ray tubes are also disadvantageous in that the resolution is lowered at peripheral edges of displayed images, resulting in distortions of displayed images or figures, there is no storage capability, and no large-size display is available.
The reasons for these shortcomings are that since the electron beam radiated from the electron gun is largely deflected, the beam spot is spread in areas where the electron beam arrives obliquely at the phosphor surface of the cathode-ray tube, displaying an image obliquely and distorting the displayed image, and that there is a limitation on efforts to keep the large space in a vacuum within the cathode-ray tube.
Liquid crystal display panels can be reduced in overall size and consume small electric energy, but are low in raster luminance and provide a limited angle of view. The liquid crystal display panels also suffer difficulty in that their drive circuit is very complex because image gradations are expressed by way of voltage levels.
For example, in the case where digital data lines are employed, the drive circuit therefor comprises a latch circuit for holding component RGB data (each of 8 bits) for a given period of time, a voltage selector, a multiplexer for switching between as many voltage levels as the number of gradations, and an output circuit for applying output data from the multiplexer to the digital data lines. As the number of gradations increases, the multiplexer needs to switch between many voltage levels and hence requires a complex circuit arrangement.
In the case where analog data lines are employed, the drive circuit therefor comprises a shift register for arraying successively inputted component RGB data (each of 8 bits) in a horizontal direction, a latch circuit for holding parallel data from the shift register for a given period of time, a level shifter for regulating a voltage level, a D/A converter for converting output data from the level shifter to an analog signal, and an output circuit for applying an output signal from the D/A converter to the analog data lines. The D/A converter comprises an operational amplifier to produce voltages depending on gradations. If the range of gradations increases, then the D/A converter needs to employ an operational amplifier capable of outputting highly accurate voltages, and hence is complex in arrangement and highly costly.
As with the liquid crystal display panels, plasma display panels can be reduced in size because the display unit itself does not take up a volume, and can easily be viewed because the display surface is flat. Particularly, AC plasma display panels are advantageous in that they require no refresh memory on account of the storage capability of cells.
In order to give a storage capability to the cells of the plasma display panels, it is necessary to alternately switch the polarity of the applied voltage to sustain an electric discharge. To meet this requirement, the drive circuit needs to have a first pulse generator for generating sustaining pulses in an X-direction and a second pulse generator for generating sustaining pulses in a Y-direction. Accordingly, the drive circuit is necessarily complex in arrangement.
The applicant of the present application has proposed a novel display apparatus in efforts to solve the problems of the CRTs, the liquid crystal display panels, and the plasma display panels (see, for example, Japanese laid-open patent publication No. 7-287176). As shown in
FIG. 39
of the accompanying drawings, the proposed display apparatus has actuators
200
arrayed in association with respective pixels. Each of the actuators
200
has an actuator unit
208
comprising a piezoelectric/electrostrictive layer
202
and upper and lower electrodes
204
,
206
disposed respectively on upper and lower surfaces of the piezoelectric/electrostrictive layer
202
, and a base
214
comprising a vibrator
210
disposed underneath the actuator unit
208
and a mount member
212
. The lower electrode
206
of the actuator unit
208
is held in contact with the vibrator
210
, which supports the actuator unit
208
.
The base
214
, which comprises an integral combination of the vibrator
210
and the mount member
212
, is made of ceramics. The base
214
has a cavity
216
where the vibrator
210
is of a reduced thickness.
To the upper electrode
204
of the actuator unit
208
, there is connected a displacement transfer member
220
for allowing the actuator
200
to contact a light guide plate
218
through an area of a predetermined size. In the example shown in
FIG. 39
, the displacement transfer member
220
is disposed closely to the light guide plate
218
when the actuator
200
is stationary, and contacts the light guide plate
218
at a distance which is equal to or shorter than the wavelength of light when the actuator
200
is energized.
Light
222
is introduced into the light guide plate
218
from an end thereof, for example. With the refractive index of the light guide plate
218
being adjusted, the light
222
is totally reflected in its entirety without passing through front and rear surfaces of the light guide plate
218
. Then, a voltage signal depending on an attribute of an image signal is applied to the actuators
200
through the upper and lower electrodes
204
,
206
to keep the actuators
200
stationary in a normal state and displace the actuators
200
in an energized state for thereby controlling the actuators
200
to move into and out of contact with the light guide plate
218
. Diffused light (leakage light)
224
in given areas of the light guide plate
218
is thus controlled to display an image depending on the image signal on the light guide plate
218
.
The display apparatus offers advantageous in that (1) the electric energy consumption can be reduced, (2) the raster luminance can be increased, and (3) the number of pixels for displaying color images does not need to be increased as compared with the number of pixels for displaying black-and-white images.
A peripheral circuit for the above display apparatus comprises, as shown in
FIG. 40
of the accompanying drawings, a display area
230
composed of a matrix of pixels, a vertical shifting circuit
234
from which extend as many vertical selection lines
232
as the number of rows, each vertical selection line
232
being common to a number of pixels (a group of pixels) of one row, and a horizontal shifting circuit
238
from which extend as many horizontal selection lines
236
as the number of columns, each horizontal selection line
236
being common to a number of pixels (a group of pixels) of one column.
Display information (output voltage) outputted from the horizontal shifting circuit
238
to the group of pixels of a selected row is also applied to the groups of pixels of unselected rows, thus necessarily energizing unnecessary pixels (actuators). Therefore, unwanted electric energy is consumed, posing disadvantages in relation to efforts to design the display apparatus for lower electric energy consumption.
In order to select all rows in a vertical scanning period, the pixels can emit light only in a period of time represented by (the vertical scan
Akao Takayoshi
Nanataki Tsutomu
Ohwada Iwao
Takeuchi Yukihisa
Burr & Brown
NGK Insulators Ltd.
Osorio Ricardo
Shalwala Bipin
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