Liquid crystal cells – elements and systems – Particular structure – Having significant detail of cell structure only
Reexamination Certificate
2002-08-20
2003-06-17
Chowdhury, Tarifur R. (Department: 2871)
Liquid crystal cells, elements and systems
Particular structure
Having significant detail of cell structure only
C349S016000, C349S096000, C349S113000, C455S575100
Reexamination Certificate
active
06580488
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a double-faced liquid crystal display device and a mobile telecommunication terminal using the same.
2. Description of the Related Art
A related art liquid crystal display device will be described with reference to the accompanying drawings.
FIG. 1
is a sectional view showing a related art liquid crystal display device, and
FIG. 2
is a schematic view showing a double-faced display device based on the related art liquid crystal display device.
As shown in
FIG. 1
, the related art liquid crystal display device includes a lower substrate
13
, an upper substrate
12
, and a liquid crystal
14
. The lower substrate
13
includes a scan electrode pattern, a signal electrode pattern, and a pixel electrode pattern. The upper substrate
12
includes a common electrode pattern, a black matrix, and a color filter layer. The liquid crystal
14
is implanted between the upper substrate
12
and the lower substrate
13
.
Polarizers
11
and
15
are respectively disposed on the upper substrate
12
and below the lower substrate
13
to compensate a phase difference due to refraction of light when characters, numbers or figures are displayed. A reflector
16
is disposed on the bottom of the polarizer
15
to reflect light.
The upper substrate
12
and the lower substrate
13
between which the liquid crystal
14
is implanted are formed of glasses or films having excellent transmittivity of light. The electrode patterns formed in the upper substrate
12
and the lower substrate
13
may be of dot matrix types, segment types, or a mix of dot matrix and segment types.
In some applications, it is desirable to provide a double-faced display; that is, a display that can be viewed from two faces, or surfaces. One example of such an application is a folding cover type mobile telecommunicative terminal such as a cellular telephone. In this type of application, it is desirable to have a double-faced display with one display viewable on the inside of the folding cover for displaying information when the phone is in use by a user, and a second display viewable on the outside of the cover, which allows information such as caller identification information to be displayed to a user without requiring the user to open the phone.
The construction of a related art double-faced display device for displaying characters, numbers and/or figures on two faces using two conventional liquid crystal display devices of the type discussed above will now be described.
As shown in
FIG. 2
, the related art double-faced display device includes first and second liquid crystal display devices
26
a
and
26
b
having respectively, signal electrodes and scan electrodes, a controller
21
for analyzing an input video signal and outputting a control signal for displaying characters, numbers or figures, a first memory
22
comprising a volatile memory device, for temporarily storing an input signal and storing booted data to promptly process the operation of the controller
21
, a second memory
23
comprising a nonvolatile memory device, for storing an operational algorithm of the controller
21
, a first driver
24
a
for driving the signal electrodes and the scan electrodes of the first liquid crystal display device
26
a
in accordance with a control signal of the controller
21
to display a video signal, a second driver
24
b
for driving the signal electrodes and the scan electrodes of the second liquid crystal display device
26
b
in accordance with the control signal of the controller
21
to display a video signal, and first and second frame memories
25
a
and
25
b
for storing signals for displaying characters, numbers or figures, applied from the first and second drivers
24
a
and
24
b.
In other words, in a conventional double-faced display, there are provided two liquid crystal display devices having separate signal electrodes and scan electrodes, and two drivers for, respectively, the two liquid crystal display devices.
The operation of the conventional double-faced display device, in which one liquid crystal display device is attached on a front face and a second liquid crystal display device is attached on a rear face, will now be described.
When power is supplied to the system, the controller
21
accesses an operation program stored in the second memory
23
and detects the signals for displaying externally input characters, numbers or figures in a state that the system is initially booted.
At this time, if the externally input signals are detected, the controller
21
analyzes the input signals through the operational algorithm and analysis program set in the first and second memories
22
and
23
and applies the control signal for displaying characters, numbers or figures to the first and second drivers
24
a
and
24
b.
The first and second drivers
24
a
and
24
b
apply a driving signal for displaying corresponding characters, numbers or figures to the scan electrodes and the signal electrodes of the first and second liquid crystal display devices
26
a
and
26
b
attached on inner and outer surfaces of the system for double-faced display, so that the same characters, number or figures can respectively be displayed on the first and second liquid crystal display devices
26
a
and
26
b.
At this time, the first and second frame memories
25
a
and
25
b
process and store the control signal applied from the controller
21
for a frame. Then, the first and second frame memories
25
a
and
25
b
output the frame signal stored in corresponding memory areas in accordance with access signals of the first and second drivers
24
a
and
24
b
, so that corresponding characters, numbers or figures can stably be displayed on the first and second liquid crystal display devices
26
a
and
26
b.
However, the related art double-faced display device has several drawbacks.
First, to display characters, numbers or figures on two faces, two liquid crystal display devices must separately be provided. To drive the two liquid crystal display devices, two drivers corresponding to the two liquid crystal display devices must be provided. To simultaneously display two faces, a duplicated control algorithm is used. This increases power consumption and thus increases the production cost.
Furthermore, since the two drivers are provided to drive the two liquid crystal display devices, a large area is required in the system. This makes it difficult to produce a light-weight and slim-sized product. For example, in a folding cover type mobile telecommunication terminal, in order to display identification information for a calling party without opening the folding cover, two liquid crystal display devices must be provided, one attached on an inner face of the cover and the other on the outer face of the cover. This makes a light-weight and slim-sized folding cover type mobile telecommunication terminal difficult. Also, since the expensive liquid crystal display devices and drivers are additionally provided, the cost of the terminal increases.
SUMMARY OF THE INVENTION
Accordingly, the present invention is directed to a liquid crystal display device and a mobile telecommunication terminal using the same that substantially obviates one or more of the limitations and disadvantages of the related art.
An object of the present invention is to provide a double faced liquid crystal display device and a mobile telecommunication terminal using the same, in which one liquid crystal display device displays information on two faces so that messages such as caller identification information, a received message, and temporal (e.g., time and date) information can be displayed even when a folding cover is not open.
Another object of the present invention is to provide a liquid crystal display device and a mobile telecommunication terminal using the same, in which production costs can be saved and a slim-sized and light-weight mobile telecommunication terminal can be achieved.
Additional features and advantages of the invention will be set forth in th
Chowdhury Tarifur R.
LG Electronics Inc.
McKenna Long & Aldridge LLP
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