Decoder system capable of performing a plural-stage process

Details Decoder system capable of performing a plural-stage process Decoder system capable of performing a plural-stage process

1999-09-13

2004-02-24

Luu, Matthew (Department: 2672)

Computer graphics processing and selective visual display system

Computer graphics display memory system

Addressing

C345S084000, C345S564000, C345S565000, C345S566000, C345S568000, C345S468000, C358S539000, C365S230010, C365S230040, C365S230060

Reexamination Certificate

active

06697075

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to decoder systems and to methods of manufacture of such systems.
The decoder system may be used with an electrode arrangement for an array of electrically-controllable elements, comprising a series of generally parallel electrodes each for extending along a respective line of the electrically-controllable elements, and a series of driver lines for receiving driving signals and supplying them to the electrodes. An electrically-controllable array device may be provided, comprising: first and second such electrode arrangements having their electrodes crossing each other, and an array of electrically-controllable elements each disposed at a crossing of a respective one of the electrodes of the first arrangement and a respective one of the electrodes of the second arrangement. The electrically-controllable elements may, for example, be provided by respective portions of a layer of material sandwiched between the electrodes of the first and second electrode arrangements. The electrically-controllable elements may have a plurality of stable states, and they may be formed by, for example, a bistable ferroelectric liquid crystal material, with the device forming a liquid crystal display panel.
2. Description of Related Art
Such an electrode arrangement is well known, and a conventional ferroelectric liquid crystal display panel having a pair of such electrode arrangements is illustrated in FIG.
1
. The display panel
10
comprises lower and upper sheets of glass
12
,
14
, which sandwich between them a layer of ferroelectric liquid crystal material. At least one of the sheets
12
,
14
acts as a plane polarising filter, or has a polarising layer applied to it. The upper surface of the lower sheet
12
is formed with a series of elongate row electrodes
16
oriented in the left-right direction, and the lower surface of the upper sheet
14
is formed with a series of elongate column electrodes
18
oriented in the up-down direction. The electrodes are transparent and formed of, for example, indium-tin-oxide (ITO). The surfaces in contact with the liquid crystal material are treated so as to align the molecules of the liquid crystal material. The portion of the liquid crystal material at each crossing point of a row electrode
16
and a column electrode
18
provides a respective pixel of the display. The ferroelectric liquid crystal material is such that, at each crossing point, if a potential difference having a value greater than a threshold level V
T+
is applied for a sufficient time between the electrodes
16
,
18
at that crossing point, the material will change to a first state, if it is not already in that state, and if an electric field having a value in excess of a threshold level V
T−
, of opposite polarity, is applied for a sufficient time between the electrodes
16
,
18
, the material will change to a second state, if it is not already in that state. The polarising effect of the crystal on light is different in the first and second states, and in combination with the polarising effect of the sheet(s)
12
,
14
, causes the pixel to appear black in one of the states and transparent (hereinafter called “white”) in the other state.
The row electrodes
16
are each connected to a respective output of a row driver
20
, and the column electrodes
18
are each connected to a respective output of a column driver
22
. The row and column drivers
20
,
22
are controlled by a controller
24
, such as a microprocessor. The row and column drivers
20
,
22
are each operable to apply voltages to the respective electrodes
16
,
18
to cause the pixels to switch to required states so as to form an image on the display panel
10
and to change the image as required. Various driving schemes are known in the art. For example, in one scheme, a voltage V
C1
is applied by the column driver
22
to all of the column electrodes
18
, and a voltage V
R1
is sequentially applied by the row driver
20
to each of the row electrodes
16
, where V
C1
−V
R1
<V
T−
, so as to clear the display
10
row-by-row to white. Then, a voltage V
R2
is sequentially applied by the row driver
20
to the row electrodes
16
, and whilst that voltage is being applied to a particular row electrode, a voltage V
C2
is applied by the column driver
20
to one or more selected column electrodes
18
, where V
C2
−V
R2
>V
T+
, so as to write black to the pixels at the intersections of that row electrode
16
and the or each selected column electrode
18
. In another scheme, rather than clearing the whole display to white and then writing selected pixels to black, the rows are addressed sequentially and all of the pixels in the selected row are cleared to white and immediately afterwards selected pixels in that row are written to black. In a modification to this scheme, rather than addressing the rows sequentially, they are addressed as and when required. In another modification, rather than clearing a whole row of pixels to white and then writing selected pixels to black, pixels which are to be changed from black to white are written to white, and pixels which are to be changed from white to black are written to black.
There is a desire to manufacture such liquid crystal display panels with ever increasing sizes and ever increasing resolutions (decreasing row and column electrodes pitches). In the arrangement shown in
FIG. 1
, the row and column drivers
20
,
22
are fabricated in silicon, and there is a problem in providing proper interconnections between the drivers
20
,
22
and the electrodes
16
,
18
on the glass sheets
12
,
14
. It will be appreciated that with increasing sizes and increasing resolutions, the interconnection problem also increases, because the interconnections are greater in number and more closely spaced.
To tackle this problem, each electrode may be connected to a plurality of the driver lines each via a respective impedance, such as a resistor. Such an arrangement is known from patent document U.S. Pat. No. 5,034,736 which describes a driving scheme which is illustrated in
FIG. 2
of the accompanying drawings and which will now be briefly described.
In
FIG. 2
, there are two row drivers
20
L,
20
R, each of which has three outputs
1
,
2
,
3
and
4
,
5
,
6
. Output
1
of the left row driver
20
L is connected by respective resistors
26
to the left hand ends of row electrodes
16
numbered
1
,
4
,
7
. Output
2
of the left row driver
20
L is connected by respective resistors
26
to the left hand ends of row electrodes
2
,
5
,
8
. Output
3
of the left row driver
20
L is connected by respective resistors
26
to the left hand ends of row electrodes
3
,
6
,
9
. Output
4
of the right row driver
20
R is connected by respective resistors
26
to the right hand ends of row electrodes
1
,
5
,
9
. Output
5
of the right row driver
20
R is connected by respective resistors
26
to the right hand ends of row electrodes
2
,
6
,
7
. Output
6
of the right row driver
20
R is connected by respective resistors
26
to the right hand ends of row electrodes
3
,
4
,
8
. Furthermore, there are two column drivers
22
T,
22
B, each of which has three outputs
1
,
2
,
3
and
4
,
5
,
6
. The top column driver
22
T is connected to the upper ends of the column electrodes
18
by respective resistors
26
in a similar fashion to the connection of the left row driver
20
L to the left hand ends of the row electrodes
16
. Also, the bottom column driver
22
B is connected to the lower ends of the column electrodes
18
by respective resistors
26
in a similar fashion to the connection of the right row driver
20
R to the right hand ends of the row electrodes
16
.
In the example given in U.S. Pat. No. 5,034,736, all of the resistors
26
are of the same value, the drivers
20
L,
20
R,
22
T,
22
B can set their output voltages at particular levels, and the liquid crystal material has particular particular positive and negative threshold voltage

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