U.S. patent application number 11/944521 was filed with the patent office on 2008-05-29 for transflective liquid crystal display panel, liquid crystal display module and liquid crystal display thereof.
This patent application is currently assigned to CHI MEI OPTOELECTRONICS CORP.. Invention is credited to Yi-Chin Lee, Chao-Lien Lin, Ting-Yi Wu.
Application Number | 20080123000 11/944521 |
Document ID | / |
Family ID | 39463299 |
Filed Date | 2008-05-29 |
United States Patent
Application |
20080123000 |
Kind Code |
A1 |
Lin; Chao-Lien ; et
al. |
May 29, 2008 |
TRANSFLECTIVE LIQUID CRYSTAL DISPLAY PANEL, LIQUID CRYSTAL DISPLAY
MODULE AND LIQUID CRYSTAL DISPLAY THEREOF
Abstract
A transflective LCD panel includes scan lines, data lines,
transmissive pixels and reflective pixels. Each transmissive pixel
is configured to receive a transmissive pixel voltage transmitted
from one of the data lines and displays a first gray level related
to the transmissive pixel voltage. Each reflective pixel receives a
reflective pixel voltage transmitted from one of the data lines and
displays a second gray level related to the reflective pixel
voltage. When the transmissive pixel and the reflective pixel are
used to display a same gray level, the transmissive pixel voltage
and the reflective pixel voltage are predetermined such that
corresponding first and second gray levels substantially equal each
other.
Inventors: |
Lin; Chao-Lien; (Tainan,
TW) ; Wu; Ting-Yi; (Tainan, TW) ; Lee;
Yi-Chin; (Tainan, TW) |
Correspondence
Address: |
LOWE HAUPTMAN HAM & BERNER, LLP
1700 DIAGONAL ROAD, SUITE 300
ALEXANDRIA
VA
22314
US
|
Assignee: |
CHI MEI OPTOELECTRONICS
CORP.
Tainan County
TW
|
Family ID: |
39463299 |
Appl. No.: |
11/944521 |
Filed: |
November 23, 2007 |
Current U.S.
Class: |
349/33 ; 345/102;
349/114 |
Current CPC
Class: |
G09G 2300/0465 20130101;
G09G 2320/0626 20130101; G09G 2300/0456 20130101; G09G 2360/144
20130101; G09G 2310/0235 20130101; G09G 3/3611 20130101; G02F
1/133555 20130101 |
Class at
Publication: |
349/33 ; 349/114;
345/102 |
International
Class: |
G02F 1/133 20060101
G02F001/133; G02F 1/1335 20060101 G02F001/1335 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 24, 2006 |
TW |
95143644 |
Claims
1. A transflective liquid crystal display (LCD) device, comprising:
a liquid crystal layer; a plurality of scan lines; a plurality of
data lines; a plurality of transmissive pixels including a first
transmissive pixel controlled by one of the scan lines and
configured to receive a transmissive pixel voltage transmitted from
one of the data lines to drive a first portion of the liquid
crystal layer and display a first gray level related to the
transmissive pixel voltage; and a plurality of reflective pixels
including a first reflective pixel controlled by one of the scan
lines and configured to receive a reflective pixel voltage
transmitted from one of the data lines to drive a second portion of
the liquid crystal layer and display a second gray level related to
the reflective pixel voltage; wherein the transflective LCD panel
has a single cell gap.
2. The transflective LCD panel according to claim 1, wherein when
the first transmissive pixel and the first reflective pixel are
used to display a same gray level, the transmissive pixel voltage
and the reflective pixel voltage, respectively received by the
first transmissive pixel and the first reflective pixel, are
predetermined to make the first gray level and the second gray
level substantially equal to each other.
3. A transflective liquid crystal display (LCD) device, comprising:
a liquid crystal layer; a plurality of scan lines; a plurality of
data lines; at least one driving circuit configured to drive the
scan lines and the data lines; a plurality of transmissive pixels
including a first transmissive pixel controlled by one of the scan
lines and configured to receive a transmissive pixel voltage
transmitted from one of the data lines to drive a first portion of
the liquid crystal layer, wherein backlight, emitted from a
backlight source, passes through the first transmissive pixel at a
first transmittance rate related to the transmissive pixel voltage;
a plurality of reflective pixels including a first reflective pixel
controlled by one of the scan lines and configured to receive a
reflective pixel voltage transmitted from one of the data lines to
drive a second portion of the liquid crystal layer, wherein
environmental light is incident to and reflected by the first
reflective pixel at a second transmittance rate related to the
reflective pixel voltage; and a photosensor unit, configured to
sense a spectrum of the environmental light, and is electrically
connected to the driving circuit; wherein when the first
transmissive pixel and the first reflective pixel are used to
display a same gray level, the driving circuit is configured to
adjust the gray level into an adjusted gray level according to the
spectrum sensed by the photosensor unit and generate the reflective
pixel voltage according to the adjusted gray level such that the
first transmissive pixel and the first reflective pixel
respectively generate a first brightness and a second
brightness.
4. The transflective LCD module according to claim 3, wherein the
first brightness and the second brightness are substantially equal
to each other.
5. The transflective LCD module according to claim 3, wherein the
transflective LCD module has a single cell gap.
6. A transflective liquid crystal display (LCD) device, comprising:
a liquid crystal layer; a plurality of scan lines; a plurality of
data lines; a plurality of transmissive pixels including a first
transmissive pixel controlled by one of the scan lines and
configured to receive a transmissive pixel voltage transmitted from
one of the data lines to drive a first portion of the liquid
crystal layer, wherein backlight emitted from a backlight source
passes through the first transmissive pixel at a first
transmittance rate related to the transmissive pixel voltage; and a
plurality of reflective pixels including a first reflective pixel
controlled by one of the scan lines and configured to receive a
reflective pixel voltage transmitted from one of the data lines to
drive a second portion of the liquid crystal layer, wherein
environmental light is incident to and reflected by the first
reflective pixel at a second transmittance rate related to the
reflective pixel voltage; wherein a resolution of the transmissive
pixels is unequal to a resolution of the reflective pixels.
7. The transflective LCD panel according to claim 6, wherein the
plurality of transmissive pixels form a plurality of transmissive
pixel rows, the plurality of reflective pixels form a plurality of
reflective pixel rows, and the number of reflective pixel rows is
smaller than the number of transmissive pixel rows.
8. The transflective LCD panel according to claim 6, the number of
the reflective pixels is smaller than the number of the
transmissive pixels.
9. The transflective LCD panel according to claim 6, wherein the
transflective LCD panel has a single cell gap.
10. A transflective liquid crystal display (LCD) device,
comprising: a plurality of scan lines; a plurality of data lines; a
first liquid crystal layer; a second liquid crystal layer; a
plurality of transmissive pixels including a first transmissive
pixel, which is controlled by one of the scan lines and is
configured to receive a transmissive pixel voltage transmitted from
one of the data lines to drive the first liquid crystal layer; and
a plurality of reflective pixels including a first reflective
pixel, which is controlled by one of the scan lines and is
configured to receive a reflective pixel voltage transmitted from
one of the data lines to drive the second liquid crystal layer;
wherein a first align mode is associated with the first liquid
crystal layer and a second align mode is associated with the second
liquid crystal layer.
11. The transflective LCD panel according to claim 10, wherein the
aligned mode associated with the first liquid crystal layer is a
low twist TN mode, and the aligned mode associated with the second
liquid crystal layer is a hybrid aligned nematic (HAN) mode.
12. The transflective LCD panel according to claim 10, wherein the
transflective LCD panel has a single cell gap.
13. A transflective liquid crystal display (LCD) device configured
to generate a frame in a frame time, the LCD panel comprising: a
plurality of scan lines; a plurality of data lines; a first
transmissive pixel controlled by one of the scan lines and
configured to receive a plurality of transmissive pixel voltages
sequentially transmitted from one of the data lines in the frame
time, wherein a plurality of backlight colors, sequentially emitted
from a backlight source, sequentially passes through each of the
transmissive pixels in the frame time so that the transmissive
pixel sequentially displays a plurality of colors in the frame
time, and each of the plurality of colors is related to
corresponding one of the plurality of transmissive pixel voltages
respectively; and a plurality of reflective pixels, each of which
is controlled by one of the scan lines and configured to receive a
reflective pixel voltage transmitted from one of the data lines in
the frame time, wherein environmental light is reflected by each of
the plurality of reflective pixels.
14. The transflective LCD panel according to claim 13, wherein the
backlight colors are red, green and blue.
15. The transflective LCD panel according to claim 13, wherein the
plurality of reflective pixels include a red reflective pixel
having a red color filter, a green reflective pixel having a green
color filter, and a blue reflective pixel having a blue color
filter.
16. The transflective LCD panel according to claim 14, wherein the
first transmissive pixel having a first size three times a second
size of each of the plurality of reflective pixels.
17. The transflective LCD panel according to claim 13, wherein the
transflective LCD panel has a single cell gap.
Description
[0001] This application claims the benefit of Taiwan application
Serial No. 95143644, filed Nov. 24, 2006, the subject matter of
which is incorporated herein by reference in its entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The invention relates in general to a transflective liquid
crystal display (LCD), and more particularly to a transflective LCD
having a transmissive pixel and a reflective pixel, which are
respectively controlled by different pixel voltages.
[0004] 2. Description of the Related Art
[0005] In a conventional transflective liquid crystal display
(LCD), such as a vertically-aligned (VA) mode transflective LCD,
each pixel has a pixel electrode and a reflective electrode
electrically connected to each other. The pixel electrode and the
reflective electrode respectively form a transmissive region and a
reflective region, and the pixel electrode and the reflective
electrode are driven by the same pixel voltage. As for the
transmissive region, the pixel voltage influences the transmittance
rate of backlight passing through a liquid crystal layer in the
transmissive region. As for the reflective region, the pixel
voltage influences the transmittance rate of environmental light
passing through the liquid crystal layer in the reflective region,
it is emitted from an environment light source, incident to the
liquid crystal layer and then reflected outward by a reflective
layer.
[0006] The relationship between the pixel voltage and the
transmittance rate in the transmissive region, and the relationship
between the pixel voltage and the transmittance rate in the
reflective region respectively form different voltage-transmission
(V-T) curves. Usually, both of the maximum transmittance rates of
the V-T curve of the transmissive/reflective region are defined as
100%. FIG. 1 depicts V-T curves of a transmissive region and a
reflective region in a conventional transflective LCD.
[0007] As shown in FIG. 1, curve 101 is the V-T curve in the
transmissive region and curve 102 is the V-T curve in the
reflective region. When the pixel voltage is higher than a
threshold voltage|, the transmissive region and the reflective
region start to respectively generate transmittance rate
variations. At the same pixel voltage V, the transmittance rate Lt
and the transmittance rate Lr, respectively corresponding to the
transmissive region and the reflective region are not the same,
such that the gray levels of the transmissive region and the
reflective region are different from each other and the trends of
the two curves are also different from each other. Therefore, in
the pixel structure of the conventional transflective LCD, it is
difficult for one pixel voltage V to make the transmissive region
and the reflective region display the same gray level. Therefore,
the transmissive region and the reflective region in one pixel
cannot simultaneously reach the desired displaying effect.
[0008] For example, one image has to be displayed by four pixels A,
B, C and D having different gray levels. However, the same set of
pixel voltages are used, so it is impossible to make the
transmissive region and the reflective region simultaneously
display the four same gray levels. The above-mentioned problem may
be solved in the conventional transflective LCD by designing the
transmissive region and the reflective region to have different
cell gaps (also referred to as a "dual cell gaps"), for example,
the cell gap of the reflective region is about one half that of the
transmissive region. However, the manufacturing processes are
complicated and expensive.
[0009] Operationally, the light source of the reflective region
comes from the outside environment. When the environmental light
source changes, for example, when the light source changes from the
outdoor sunlight to the indoor daylight lamp, or when the sunlight
changes with time, the brightness and the color presented by the
reflective region also change. The color is the result obtained
after the light passes through the color filter. However, the light
of the transmissive region only comes from the backlight source,
and its brightness and color cannot change with the change of the
environmental light. Therefore, if the transmissive region and the
reflective region are driven by the same pixel voltage, the
brightness or colors co-presented by the transmissive region and
the reflective region often deviate from the optimum settings,
which are set when the product is finished and ready to be shipped
out, so that the incongruent condition is obtained when the
environmental light changes with the changes of the time and the
environment.
[0010] Therefore, it is an important subject in the industry to
make the displayed gray level generated by the transmissive light
the same as the displayed gray level generated by the reflective
light inan LCD. It is further important that the brightness and the
color representation of the reflective region are not changed with
the variation of the environmental light so that the image
displaying quality can be enhanced.
SUMMARY OF THE INVENTION
[0011] The invention is directed to a transflective LCD having a
transmissive pixel and a reflective pixel respectively driven by a
transmissive pixel voltage and a reflective pixel voltage.
Independently controlling the transmissive pixel and the reflective
pixel allows the brightness or the gray level displayed by the
transmissive pixel and the reflective pixel to achieve a desired
effect, thereby enhancing the image displaying quality.
[0012] According to a first aspect of the present invention, a
transflective LCD panel including a liquid crystal layer, scan
lines, data lines, transmissive pixels and reflective pixels is
provided. The data lines are disposed substantially perpendicular
to the scan lines. The transmissive pixels include a first
transmissive pixel. The first transmissive pixel is controlled by
one of the scan lines, receives a transmissive pixel voltage
transmitted from one of the data lines to drive a first portion of
liquid crystal layer, and displays a first gray level related to
the transmissive pixel voltage. The reflective pixels include a
first reflective pixel. The first reflective pixel is controlled by
one of the scan lines, receives a reflective pixel voltage
transmitted from one of the data lines to drive a second portion of
liquid crystal layer, and displays a second gray level related to
the reflective pixel voltage. When the first transmissive pixel and
the first reflective pixel are used to display the same gray level,
the received transmissive pixel voltage and the reflective pixel
voltage are such that the corresponding first and second gray
levels are substantially equal to each other.
[0013] According to a second aspect of the present invention, a
transflective LCD, including a backlight element, a liquid crystal
layer, scan lines, data lines, transmissive pixels and reflective
pixels is provided. The backlight element provides a backlight
source. The data lines are disposed substantially perpendicular to
the scan lines. The transmissive pixels include a first
transmissive pixel. The first transmissive pixel is controlled by
one of the scan lines, receives a transmissive pixel voltage
transmitted from one of the data lines to drive a first portion of
liquid crystal layer, and displays a first gray level related to
the transmissive pixel voltage. The reflective pixels include a
first reflective pixel. The first reflective pixel is controlled by
one of the scan lines, receives a reflective pixel voltage
transmitted from one of the data lines to drive a second portion of
liquid crystal layer, and displays a second gray level related to
the reflective pixel voltage. When the first transmissive pixel and
the first reflective pixel are used to display the same gray level,
the received transmissive pixel voltage and the reflective pixel
voltage are such that the corresponding first and second gray
levels are substantially equal to each other.
[0014] According to a third aspect of the present invention, a
transflective LCD module including a liquid crystal layer, scan
lines, data lines, at least one driving circuit, a photosensor
unit, transmissive pixels and reflective pixels is provided. The
driving circuit drives the scan lines and the data lines. The
transmissive pixels include a first transmissive pixel. The first
transmissive pixel is controlled by one of the scan lines and
receives a transmissive pixel voltage transmitted from one of the
data lines to drive a first portion of liquid crystal layer.
Backlight emitted from a backlight source passes through the first
transmissive pixel at a first transmittance rate related to the
transmissive pixel voltage. The reflective pixels include a first
reflective pixel. The first reflective pixel is controlled by one
of the scan lines and receives a reflective pixel voltage
transmitted from one of the data lines to drive a second portion of
liquid crystal layer. Environmental light is incident to and
reflected by the first reflective pixel at a second transmittance
rate related to the reflective pixel voltage. The photosensor unit
senses a spectrum of the environmental light and is electrically
connected to the driving circuit. When the first transmissive pixel
and the first reflective pixel are used to display the same
original gray level, the driving circuit adjusts the original gray
level into an adjusted gray level according to the spectrum sensed
by the photosensor unit, and generates the reflective pixel voltage
according to the adjusted gray level, such that the first
transmissive pixel and the first reflective pixel respectively
generate the same brightness.
[0015] According to a fourth aspect of the present invention, a
transflective LCD includes a backlight element, a liquid crystal
layer, scan lines, data lines, at least one driving circuit, a
photosensor unit, transmissive pixels and reflective pixels. The
backlight element is for providing a backlight source. The driving
circuit is for driving the scan lines and the data lines. The
transmissive pixels include a first transmissive pixel. The first
transmissive pixel is controlled by one of the scan lines, and
receives a transmissive pixel voltage transmitted from one of the
data lines to drive a first portion of liquid crystal layer.
Backlight emitted from the backlight source passes through the
first transmissive pixel at a first transmittance rate related to
the transmissive pixel voltage. The reflective pixels include a
first reflective pixel. The first reflective pixel is controlled by
one of the scan lines, and receives a reflective pixel voltage
transmitted from one of the data lines to drive a second portion of
liquid crystal layer. Environmental light is incident to and
reflected by the first reflective pixel at a second transmittance
rate related to the reflective pixel voltage. The photosensor unit
senses a spectrum of the environmental light, and is electrically
connected to the driving circuit. When the first transmissive pixel
and the first reflective pixel are used to display the same
original gray level, the driving circuit adjusts the original gray
level into an adjusted gray level according to the spectrum sensed
by the photosensor unit, and generates the reflective pixel voltage
according to the adjusted gray level such that the first
transmissive pixel and the first reflective pixel respectively
generate the same brightness.
[0016] According to a fifth aspect of the present invention, a
transflective LCD panel includes a liquid crystal layer, scan
lines, data lines, transmissive pixels and reflective pixels. The
transmissive pixels include a first transmissive pixel. The first
transmissive pixel is controlled by one of the scan lines and
receives a transmissive pixel voltage transmitted from one of the
data lines to drive a first portion of liquid crystal layer.
Backlight emitted from a backlight source passes through the first
transmissive pixel at a first transmittance rate related to the
transmissive pixel voltage. The reflective pixels include a first
reflective pixel. The first reflective pixel is controlled by one
of the scan lines and receives a reflective pixel voltage
transmitted from one of the data lines to drive a second portion of
liquid crystal layer. Environmental light is incident to and
reflected by the first reflective pixel at a second transmittance
rate related to the reflective pixel voltage. A resolution of the
transmissive pixels is unequal to a resolution of the reflective
pixels.
[0017] According to a sixth aspect of the present invention, a
transflective LCD includes at least one backlight element, a liquid
crystal layer, scan lines, data lines, transmissive pixels and
reflective pixels. The backlight element provides a backlight
source. The transmissive pixels include a first transmissive pixel.
The first transmissive pixel is controlled by one of the scan lines
and receives a transmissive pixel voltage transmitted from one of
the data lines to drive a first portion of liquid crystal layer.
Backlight emitted from the backlight source passes through the
first transmissive pixel at a first transmittance rate related to
the transmissive pixel voltage. The reflective pixels include a
first reflective pixel. The first reflective pixel is controlled by
one of the scan lines and receives a reflective pixel voltage
transmitted from one of the data lines to drive a second portion of
liquid crystal layer. Environmental light is incident to and
reflected by the first reflective pixel at a second transmittance
rate related to the reflective pixel voltage. A resolution of the
transmissive pixels is unequal to a resolution of the reflective
pixels.
[0018] According to a seventh aspect of the present invention, a
transflective LCD panel includes scan lines, data lines, a first
liquid crystal layer, a second liquid crystal layer, transmissive
pixels and reflective pixels. The transmissive pixels include a
first transmissive pixel. The first transmissive pixel is
controlled by one of the scan lines and receives a transmissive
pixel voltage transmitted from one of the data lines to drive the
first liquid crystal layer. The reflective pixels include a first
reflective pixel. The first reflective pixel is controlled by one
of the scan lines and receives a reflective pixel voltage
transmitted from one of the data lines to drive the second liquid
crystal layer. The liquid crystal molecules of the first liquid
crystal layer and the liquid crystal molecules of the second liquid
crystal layer pertain to different aligned modes.
[0019] According to an eighth aspect of the present invention, a
transflective LCD includes a backlight element, scan lines, data
lines, a first liquid crystal layer, a second liquid crystal layer,
transmissive pixels and reflective pixels. The backlight element
provides a backlight source. The transmissive pixels include a
first transmissive pixel. The first transmissive pixel is
controlled by one of the scan lines and receives a transmissive
pixel voltage transmitted from one of the data lines to drive the
first liquid crystal layer. The reflective pixels include a first
reflective pixel. The first reflective pixel is controlled by one
of the scan lines and receives a reflective pixel voltage
transmitted from one of the data lines to drive the second liquid
crystal layer. The liquid crystal molecules of the first liquid
crystal layer and the liquid crystal molecules of the second liquid
crystal layer pertain to different aligned modes.
[0020] According to a ninth aspect of the present invention, a
transflective LCD panel for generating a frame in a frame time is
provided. The transflective LCD panel includes scan lines, data
lines, transmissive pixels and reflective pixels. Each transmissive
pixel is controlled by one of the scan lines and receives
transmissive pixel voltages transmitted from one of the data lines.
Several colors of backlight, sequentially emitted from a backlight
source, sequentially pass through each transmissive pixel to make
each transmissive pixel sequentially display several colors in the
frame time. Each reflective pixel is controlled by one of the scan
lines and receives a reflective pixel voltage transmitted from one
of the data lines. Environmental light is reflected by a first
reflective pixel.
[0021] According to a tenth aspect of the present invention, a
transflective LCD for generating a frame in a frame time is
provided. The transflective LCD includes a backlight element, scan
lines, data lines, transmissive pixels and reflective pixels. The
backlight element provides a backlight source. Each transmissive
pixel is controlled by one of the scan lines and receives
transmissive pixel voltages transmitted from one of the data lines.
Several colors of backlight, sequentially emitted from the
backlight source, sequentially pass through each transmissive pixel
to make each transmissive pixel sequentially display several colors
in the frame time. Each reflective pixel is controlled by one of
the scan lines, and receives a reflective pixel voltage transmitted
from one of the data lines. Environmental light is reflected by a
first reflective pixel.
[0022] The invention will become apparent from the following
detailed description of the preferred but non-limiting embodiments.
The following description is made with reference to the
accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] FIG. 1 depicts V-T curves of a transmissive region and a
reflective region in a conventional transflective LCD.
[0024] FIG. 2 is a partial schematic depicting a transflective LCD
panel according to a first embodiment of the invention.
[0025] FIG. 3 depicts V-T curves of a transmissive pixel and a
reflective pixel in the transflective LCD panel according to the
first embodiment of the invention.
[0026] FIG. 4 is a side view depicting structures of the
transmissive pixel and the reflective pixel in the transflective
LCD of the transflective LCD panel of FIG. 2.
[0027] FIG. 5 depicts spectrums of environmental light and
backlight.
[0028] FIG. 6 depicts a block diagram of a transflective LCD module
according to a second embodiment of the invention.
[0029] FIG. 7 depicts a transflective LCD panel according to a
third embodiment of the invention.
[0030] FIG. 8 depicts V-T curves of a transmissive pixel and a
reflective pixel in a transflective LCD panel according to a fourth
embodiment of the invention.
[0031] FIGS. 9A and 9B depict processes for different aligned modes
of liquid crystal layers.
[0032] FIG. 10 depicts an arrangement of pixels in the
transflective LCD panel according to a fifth embodiment of the
invention.
DETAILED DESCRIPTION OF THE INVENTION
[0033] In a transflective LCD panel and the display thereof, a
transmissive pixel and a reflective pixel are respectively driven
by a transmissive pixel voltage and a reflective pixel voltage so
that the transmissive pixel and the reflective pixel are controlled
independently, attaining simultaneously, the desired effect of
brightness displayed by the transmissive pixel and the brightness
displayed by the reflective pixel, thereby enhancing the image
displaying quality. Thus, the problems of conventional
transflective LCD panels, in which the transmissive region and the
reflective region of the same pixel are only controlled by the same
pixel voltage, such that the transmissive region and the reflective
region cannot simultaneously provide a quality display effect, may
be solved.
First Embodiment
[0034] FIG. 2 is a partial schematic illustrating transflective LCD
panel 200 according to a first embodiment of the invention.
Transflective LCD panel 200 includes a plurality of scan lines, a
plurality of data lines, a plurality of transmissive pixels 201
(represented by "T"), and a plurality of reflective pixels 202
(represented by "R"). Referring to FIG. 2, it shows scan lines SC1
and SC2, a data line DT1, a transmissive pixel 201 and a reflective
pixel 202 of the transflective LCD panel 200. The transmissive
pixel 201 is controlled by the scan line SC1 and receives the
transmissive pixel voltage transmitted from the data line DT1. The
backlight emitted from a backlight source passes through the
transmissive pixel 201 at a transmittance rate related to the
transmissive pixel voltage. The reflective pixel 202 is controlled
by the scan line SC2, and receives the reflective pixel voltage
transmitted from the data line DT1. The input timings and sequence
of the transmissive pixel voltage of the transmissive pixel 201 and
the reflective pixel voltage of the reflective pixel 202 are
controlled by the switching timings of the scan lines SC1 and SC2.
The environmental light emitted from an environmental light source
passes through the reflective pixel 202 at a transmittance rate
related to the reflective pixel voltage. The transmissive pixel 201
and the reflective pixel 202 are respectively driven by the
transmissive pixel voltage and the reflective pixel voltage.
Accordingly, when the transmissive pixel 201 and the reflective
pixel 202 are used to display the same gray level, the proper
transmissive pixel voltage and the proper reflective pixel voltage
are respectively inputted such that the transmittance rate of the
transmissive pixel 201 and the transmittance rate of the reflective
pixel 202 are substantially equal to each other.
[0035] FIG. 3 shows V-T curves of the transmissive pixel 201 and
the reflective pixel 202 in the transflective LCD panel of FIG. 2.
In detail, the curve 301 is a V-T curve of the transmissive pixel
201, the curve 302 is a V-T curve of the reflective pixel 202. When
the transmissive pixel voltage or the reflective pixel voltage is
greater than a threshold voltage, not shown, the transmissive pixel
201 or the reflective pixel 202 starts to generate a transmittance
rate variation. When the transmissive pixel 201 and the reflective
pixel 202 are used to display the same gray level, the transmissive
pixel voltage Vt and the reflective pixel voltage Vr are
respectively inputted such that the transmittance rate of the
transmissive pixel 201 and the transmittance rate of the reflective
pixel 202 are equal to transmittance rate L, corresponding to the
same gray level, that is, the transmissive pixel 201 and the
reflective pixel 202 can display the same gray level L. In general,
the gray level corresponds to the transmittance rate, that is, the
maximum gray level (i.e., 255) corresponds to the maximum
transmittance rate 100% and vice versa for the minimum gray
level.
[0036] In addition, the transflective LCD panel 200 of this
embodiment has a single cell gap.
[0037] In the transmissive pixel 201 and the reflective pixel 202
of the transflective LCD panel 200 according to the first
embodiment of FIG. 2, the transmissive pixel 201 and the reflective
pixel 202 respectively receive the transmissive pixel voltage and
the reflective pixel voltage through the same data line DT1, and
the transmissive pixel 201 and the reflective pixel 202 are driven
by different scan lines SC1 and SC2. Non-limiting, the transmissive
pixel 201 and the reflective pixel 202 may also receive the
transmissive pixel voltage and the reflective pixel voltage through
different data lines, and the transmissive pixel 201 and the
reflective pixel 202 may also be controlled by the same scan line|.
Any transflective LCD panel having the transmissive pixel and the
reflective pixel, which are driven by the independently generated
transmissive pixel voltage and reflective pixel voltage, is deemed
as falling within the scope of this embodiment.
[0038] FIG. 4 is a side view illustrating structures of the
transmissive pixel 201 and the reflective pixel 202 in the
transflective LCD of the transflective LCD panel of FIG. 2. A
single cell gap G exists between an upper substrate 406 and a lower
substrate 409 of the transflective LCD. A liquid crystal layer 403
is disposed between the upper substrate 406 and the lower substrate
409. The transmissive pixel voltage received by the transmissive
pixel 201 is transmitted to a pixel electrode 410 to change the
orientation of the liquid crystal molecules of the liquid crystal
layer 403 of the transmissive pixel 201. Thus, the transmissive
pixel 201 displays a first gray level after a backlight beam 407,
emitted from a backlight element 404, passes through the liquid
crystal layer 403.
[0039] Regarding reflective pixel 202, the reflective pixel voltage
received by the reflective pixel 202 is transmitted to a reflective
electrode 405 to change the orientation of the liquid crystal
molecules of the liquid crystal layer 403 of the reflective pixel
202. An environmental light beam 408 emitted from an environmental
light source is reflected by the reflective electrode 405 such that
the reflective pixel 202 displays a second gray level, which is
substantially equal to the first gray level.
[0040] When the transmissive pixel and the reflective pixel are
desired to display a specific gray-scale distribution (e.g., four
transmissive pixels and four reflective pixels are to display four
gray levels A>B>C>D), the four transmissive pixels and the
four reflective pixels will not display different sets of four gray
levels, such as A>B>C>D and E<F>G>H, which would
make the frame data disordered and deteriorates the displaying
quality. In addition, this embodiment is distinguished from the
prior art,| it uses a single cell gap instead of a dual cell gap.
Furthermore, this embodiment requires simpler manufacturing
processes enabling a reduction in manufacturing costs.
Second Embodiment
[0041] The light for the reflective pixel comes from the
environmental light and the light for the transmissive pixel comes
from the backlight, so the spectrums of the environmental light and
the backlight are usually different, as illustrated in the
spectrums of FIG. 5. A spectrum 501 is a backlight spectrum and a
spectrum 502 is an environmental light spectrum wherein spectrum
502 changes with a change of the spatiotemporal environment.
[0042] With regard to the transmissive pixel and the reflective
pixel needing to simultaneously display the same gray level, the
displayed brightness of the transmissive pixel is substantially
different from the displayed brightness of the reflective pixel
because the light source spectrums of the transmissive pixel and
the reflective pixel are different from each other. Consequently,
some specific black-and-white brightness or color, which is to be
displayed in the frame, is influenced by the environmental light of
the reflective pixel and is thus distorted. Further, the spectrum
of the environmental light changes with the spatiotemporal
environment, making the problem of color or brightness distortion
more serious.
[0043] FIG. 6 is a block diagram illustrating a transflective LCD
module according to a second embodiment of the invention, wherein a
transmissive pixel 603 receives a transmissive pixel voltage Vt
outputted from a driving circuit 602, and the backlight, emitted
from a backlight source, passes through the transmissive pixel 603
at a transmittance rate related to the transmissive pixel voltage
Vt. A reflective pixel 604 receives the reflective pixel voltage Vr
outputted from the driving circuit 602, and the environmental light
emitted from the environmental light source passes through the
reflective pixel 604 at a transmittance rate related to the
reflective pixel voltage Vr.
[0044] This embodiment is distinguished from the first embodiment
in that the transflective LCD module of the second embodiment has a
photosensor unit 601, which is electrically connected to a driving
circuit 602. This driving circuit includes a data driver, a scan
driver and a timing controller. The photosensor unit 601 senses a
spectrum of the environmental light emitted from the environmental
light source. The driving circuit 602 adjusts the original gray
level corresponding to the reflective pixel 604 into a corrected
gray level according to a compared result between the spectrum
sensed by photosensor unit 601 and the spectrum of the backlight
source so that a same brightness as that of the transmissive pixel
603 can be displayed, and the voltage for controlling the
reflective pixel can be generated according to the adjusted gray
level. Consequently, when the transmissive pixel 603 and the
reflective pixel 604 simultaneously display the brightness
corresponding to the original gray level, the displayed brightness
of the transmissive pixel 603 and the displayed brightness of the
reflective pixel 604 can be made substantially equal to each other
by generating the transmissive pixel voltage Vt corresponding to
the original gray level and by generating the reflective pixel
voltage Vr corresponding to the adjusted gray level.
[0045] In the transflective LCD module according to the second
embodiment of the embodiment, the photosensor unit 601 senses the
spectrum of the environmental light to adjust the gray level
displayed by the reflective pixel 604. Thus, not only can the
transmissive pixel and the reflective pixel display the same gray
level in a manner similar to that of the first embodiment, but
further the substantially same brightness can also be displayed.
For example, when the environmental light spectrum of the
environment of the transflective LCD module changes, e.g., when the
environmental light changes from indoor light to sunlight, the
transflective LCD module of this embodiment still can reduce the
difference between the images displayed by the reflective pixel and
the transmissive pixel and particularly improve elimination of
differences between the colors displayed by the two pixels.
[0046] A transflective LCD is further provided that includes a
backlight element and the transflective LCD module of the second
embodiment. The backlight element provides the backlight and is
disposed in a same manner as that of the transflective LCD
according to the first embodiment illustrated in FIG. 4.
Third Embodiment
[0047] FIG. 7 illustrates a transflective LCD panel according to a
third embodiment of the invention. The LCD panel illustrated in
FIG. 7 is distinguished from that of the first embodiment in that
the LCD panel of the third embodiment has a number of transmissive
pixels T and a number of reflective pixels R, and the resolution of
the transmissive pixels is unequal to the resolution of the
reflective pixels. The transmissive pixels form a number of
transmissive pixel rows including, for example, transmissive pixel
rows 701 and 703. The reflective pixels form reflective pixel rows
including, for example, reflective pixel row 702.
[0048] The transmissive pixel T receives the transmissive pixel
voltage transmitted from the data line. The backlight emitted from
a backlight source passes through the transmissive pixel at a
transmittance rate related to the transmissive pixel voltage. The
reflective pixel R receives the reflective pixel voltage
transmitted from the data line. The environmental light emitted
from an environmental light source passes through the reflective
pixel at a transmittance rate related to the reflective pixel
voltage. The number of the transmissive pixels of this embodiment
is preferably greater than that of the reflective pixels, and the
number of the transmissive pixel rows is preferably greater than
that of the reflective pixel rows. The ratio of the number of the
transmissive pixel rows to the number of the reflective pixel rows
in FIG. 7 is 2:1. Consequently, the scan signals scan the
transmissive pixels and the reflective pixel rows at a scan
frequency ratio of 2:1.
[0049] Such a design enables the reflective pixels to be applied to
applications, such as time annunciation, ticker annunciation, and
the like, in which a mobile telephone or other types of displays
can display frames |simply|, and the display resolution needs not
to be too high. At this time, it is capable to skip scanning the
transmissive pixel rows, and only scan the reflective pixel rows.
Furthermore, this kind of display mode has a lower demand on
brightness or color, so the requirement can be fulfilled by
designing the reflective pixel rows, which use the environmental
light source as the light source, to be the pixel rows with the
lower resolution. Compared with the first embodiment, this
embodiment can decrease power consumption and achieve a
power-saving effect by greatly reducing the times of scanning the
transmissive pixel rows|.
[0050] In this embodiment, the ratio of the number of the
transmissive pixel rows to the number of the reflective pixel rows
is approximately 2:1. In practice, a different ratio can be
adopted, and the resolutions of the transmissive pixels and the
reflective pixels can be adjusted by any other method. For example,
the number of the reflective pixel rows can be decreased to achieve
a power-saving effect. Any transflective LCD panel capable of
achieving the power-saving effect by adjusting the resolution of
the transmissive pixels and the resolution of the reflective pixels
falls within the scope of this embodiment.
[0051] The invention further provides a transflective LCD that
includes a backlight element and the transflective LCD panel of the
third embodiment. The backlight element provides the backlight, and
the backlight element is disposed in a manner similar to that of
the transflective LCD, according to the first embodiment
illustrated in FIG. 4.
Fourth Embodiment
[0052] FIG. 8 shows V-T curves of a transmissive pixel and a
reflective pixel in a transflective LCD panel according to a fourth
embodiment of the invention. As shown in FIG. 8, curve 801 is a V-T
curve for the transmissive pixel, and curve 802 is a V-T curve for
the reflective pixel. What is different from the first embodiment
is that the fourth embodiment is applied to a multi-mode LCD panel
having a plurality of modes, such as a dual-mode display, in which
the aligned mode of the liquid crystal layer of the transmissive
pixel is a low twist TN mode, and the aligned mode of the liquid
crystal layer of the reflective pixel is a hybrid aligned nematic
(HAN) mode. The transmissive pixel and the reflective pixel in this
dual-mode LCD panel use different liquid crystal aligned modes and
thus respectively have different V-T curves, as shown in FIG. 8.
Thus, similar to a conventional VA mode transflective LCD panel,
this embodiment still has the problem that the display control of
both of the transmissive pixel and the reflective pixel cannot be
optimized when the pixels are driven by the same pixel voltage.
[0053] FIGS. 9A and 9B illustrate processes for different aligned
modes of liquid crystal layers. In order to obtain the liquid
crystal layer of the transmissive pixels and the liquid crystal
layer of the reflective pixels, which have different aligned modes,
two substrates of the transflective LCD of this embodiment are
covered by a vertically aligned film (polyimide, AL-00010). The
vertically aligned film of the upper substrate (not shown) is
illuminated by an argon ion light beam with 200 electron volts (eV)
for 40 seconds. In FIG. 9A, a vertically aligned film 905 of the
lower substrate in a transmissive pixel 901 is illuminated by an
Argon ion light beam 906 with 200 eV for 40 seconds. In a
reflective pixel 902, the vertically aligned film 905 of the lower
substrate is covered by a protective film 904 to isolate the argon
ion light beam 906. In FIG. 9B, the vertically aligned film 905 of
the transmissive pixel 901 is illuminated by the Argon ion light
beam 906, and then the aligned mode of the liquid crystal layer of
the transmissive pixel 901 becomes the low twist TN mode, while the
aligned mode of the liquid crystal layer of the reflective pixel
902 becomes the HAN mode.
[0054] This embodiment adopts the pixel design similar to the first
embodiment such that the transmissive pixel and the reflective
pixel are driven by different pixel voltages to display the same
gray level, and therefore, the display control can be
optimized.
[0055] A transflective LCD is further provided that includes a
backlight element and the transflective LCD panel of the fourth
embodiment. The backlight element provides the backlight and is
disposed in a manner similar to that of the transflective LCD
according to the first embodiment of FIG. 4.
Fifth Embodiment
[0056] FIG. 10 illustrates an arrangement of pixels in the
transflective LCD panel according to a fifth embodiment, wherein
three transmissive pixels, each of which having a size the same as
that of the reflective pixel and controlled by an individual thin
film transistor, are replaced with a transmissive pixel, which has
a size three times that of the reflective pixel and is controlled
by one thin film transistor so that the aperture rate can be
enhanced.
[0057] A transmissive pixel 111 sequentially receives a plurality
of transmissive pixel voltages, and the backlight emitted from the
backlight source passes through the transmissive pixel 111 at a
transmittance rates related to the transmissive pixel voltages.
Each of reflective pixels 112, 113, and 114 receives one reflective
pixel voltage individually, and the environmental light emitted
from the environmental light source passes through reflective
pixels 112, 113, and 114 at transmittance rates related to the
receive reflective pixel voltages.
[0058] What is different from the first embodiment is that the
transmissive pixel 111 is driven by field sequential color (FSC)
technology. In a frame time of generating a frame, the backlight,
which is emitted from the backlight source, has several colors
sequentially passing through the transmissive pixel 111 without the
use of a color filter, so that transmissive pixel 111 sequentially
displays several transmissive colors, such as red, green and blue
colors, in one frame time. The backlight source includes red, green
and blue light emitting diodes (LEDs), which are energized
according to a timing sequence. The transmissive pixel voltages are
sequentially adjusted |in one frame time |to adjust the
transmittance rates when the transmissive pixel is displaying red,
green, or blue colors respectively, to generate a desired color
according to the persistence of vision of the human eyes, the
desired color is same as the mixture of colors co-presented by
three smaller transmissive pixels (those are red, green and blue
pixels) each having the size as the reflective pixel.
[0059] Each of the reflective pixels 112, 113, and 114 has red,
blue and green color filters because the environmental light
required by the reflective pixel cannot emit the above-mentioned
three-color light individually, the reflected environmental light
need to passes through the red color filter, the blue color filter,
and the green color filter such that reflective pixels 112, 113,
and 114 respectively generate red, green and blue colors, and the
desired color for the reflective pixel is generated by way of
mixing.
[0060] The field sequential color technology originally applied to
the transmissive LCD is restricted by the conventional problem that
the transmissive region and the reflective region of the
transflective LCD are driven by the same pixel voltage, so that the
prior art method cannot be easily implemented in the transflective
LCD.
[0061] Still referring to the pixel of the transflective display
panel of FIG. 10, a frame scanning frequency of 60 Hz results in a
scanning period of 16.67 ms for each frame. Therefore, when the
transmissive pixel 111 and the reflective pixels 112, 113, and 114
display the same color, the transmissive pixel 111 sequentially
finishes displaying the red, green and blue colors within 16.67 ms,
and the displaying time of each color is only 5.56 ms (16.67/3).
The reflective pixels 112, 113, and 114 respectively display the
red, green and blue colors within the same 16.67 ms, so that the
desired color can be generated by way of mixing. Because the
transmissive pixel and the reflective pixel are independently
driven by different pixel voltages, the field sequential color
technology can be applied to the transflective LCD.
[0062] For example, a certain color is decomposed into three
primary colors, respectively having gray levels of 30 for red, 50
for green and 100 for blue. The transmissive pixel 111 respectively
displays the red, green and blue colors at a brightness
corresponding to the gray levels of 30, 50, and 100 within |5|.56
ms, and the reflective pixels 112, 113 and 114 individually display
a brightness corresponding to gray levels of 30, 50 and 100 within
16.67 ms.
[0063] In the transflective LCD panel of the illustrative
embodiment, the transmissive pixel sequentially displays the red,
green and blue colors in one frame time, and the three reflective
pixels respectively display the red, green and blue colors in one
frame time. Non-limiting, the transmissive pixel can display other
colors, and the reflective pixel may also display other colors. Any
transflective LCD panel having the transmissive pixel using field
sequential color technology falls within the scope of this
embodiment.
[0064] The invention further provides a transflective LCD that
includes a backlight element and the transflective LCD panel of the
fifth embodiment. The backlight element provides the backlight and
is disposed in a manner similar to that of the transflective LCD
according to the first embodiment of FIG. 4.
[0065] The transflective LCD panel according to this embodiment
uses field sequential color technology in the transmissive pixels
to increase the aperture rate of the liquid crystal panel and
decrease the high cost of the color filter disposed in the
transmissive pixel. Thus, it is possible to prevent the retained
image generated when the frame changes severely, thus enhancing the
display quality of the motion picture.
[0066] In the transflective LCD, the LCD module, and the LCD
thereof, the transmissive pixel and the reflective pixel are
respectively driven by the transmissive pixel voltage and the
reflective pixel voltage. Independent control of the transmissive
pixel and the reflective pixel enables the individual brightness or
gray level of both pixels to attain a desired same level so that
the image displaying quality can be enhanced. Furthermore,
manufacturing costs may be reduced.
[0067] While the invention has been described by way of examples
and in terms of preferred embodiments, it is to be understood that
the invention is not limited thereto. On the contrary, it is
intended to cover various modifications and similar arrangements
and procedures, and the scope of the appended claims therefore
should be accorded the broadest interpretation so as to encompass
all such modifications and similar arrangements and procedures.
* * * * *