Electric lamp and discharge devices: systems – Plural power supplies – Plural cathode and/or anode load device
Reexamination Certificate
2003-03-19
2004-12-07
Wong, Don (Department: 2821)
Electric lamp and discharge devices: systems
Plural power supplies
Plural cathode and/or anode load device
C315S169300, C349S149000
Reexamination Certificate
active
06828734
ABSTRACT:
BACKGROUND OF INVENTION
1. Field of the Invention
This invention relates to a display device, especially to a technology for reducing display device size by improving layout flexibility of peripheral driving circuits.
2. Description of the Related Art
A flat panel display device including a reflection type active matrix liquid crystal display device (referred to as LCD hereinafter) can be thin, small and light, and it operates with low-power consumption. The LCD has been used as a display part in various devices such as mobile information device. The LCD, whose pixel has a switching element and a thin film transistor, is known as an active matrix type. The panel of the active matrix display device is highly reliable for maintaining displayed contents of the pixels, which provides the active matrix display device with high display quality.
FIG. 3
shows an equivalent circuit of a pixel in the active matrix LCD. Each pixel has a thin film transistor (TFT)
11
connected to a gate line and a data line. When the TFT
11
is turned on by a selection signal outputted to the gate line, the data corresponding to the display content is supplied to a liquid crystal capacitance (Clc)
15
from the data line through the TFT
11
. It is necessary to accurately keep the display data from the time when the TFT
11
is first selected for writing to the time when the TFT
11
is selected again in the next sequence. Therefore, a storage capacitance (Csc)
13
is connected to the TFT
11
in series with the liquid crystal capacitance Clc
15
.
FIG. 4
is a plan view showing the configuration of a LCD panel
300
as a whole. A display region
100
is disposed in the middle of the LCD panel
300
. The display pixels are disposed in a matrix configuration on the display region
100
. And peripheral driving circuits including an H scanner (a horizontal driving circuit)
101
, a HSW circuit
102
, a PSW circuit
103
, a V scanner (a vertical driving circuit)
104
and a group of input terminals
105
are disposed near the inside wall of the display region
100
.
The H scanner
101
generates a horizontal scanning signal. The HSW circuit
102
is a switching circuit for supplying a video signal to the data line based on the horizontal scanning signal. The PSW circuit
103
is a switching circuit, which is connected to all the data lines and turns them on and off simultaneously. When the PSW circuit
103
is on, it supplies a pre-charge data (pre-charge signal) from a pre-charge bus line to all the data lines.
The V scanner
104
is a circuit for outputting a vertical scanning signal, which becomes high for each of the horizontal period, as the selection signal described above is applied to the gate line.
An HVDD (a source voltage for the H scanner), a VSS (an earth voltage), the pre-charge data, a VVDD (a source voltage for the V scanner) and a VCOM (a common voltage) are inputted from the group of input terminals
105
, and an HVDD bus line
110
, a VSS bus line
111
, the pre-charge data bus line
112
, a VVDD bus line
113
, and a COM bus line
114
corresponding to the above mentioned voltages are disposed around the display region
100
. These bus lines
110
-
114
supply the data and the voltages necessary for peripheral driving circuits.
However, since various bus lines
110
-
114
are formed as a part of the wiring layer that is made of poly-silicon or an aluminum and is also used for the peripheral driving circuit, there is a certain restriction in terms of the circuit layout. Additionally, it is necessary to reduce the time constant of these bus lines
110
-
114
. Therefore, for a larger LCD panel, a wider wiring area is required, enlarging the framing area of the LCD panel
300
.
SUMMARY OF THE INVENTION
The invention provides a display device having a plurality of wiring layers. The display device includes a display region having a plurality of display pixels and a peripheral driving circuit that supplies a driving signal to each of the display pixels and is disposed outside the display region. The display device also includes a bus line that supplies a voltage to the peripheral driving circuit and a pixel electrode disposed for each of the display pixels. The bus line and the pixel electrodes are disposed in one of the wiring layers, and at least a portion of the peripheral driving circuit is disposed in a wiring layer that is disposed below the wiring layer of the bus line and the pixel electrodes.
The invention also provides a reflection-type display device having a plurality of wiring layers. The display device includes a display region having a plurality of display pixels and a peripheral driving circuit that supplies a driving signal to each of the display pixels and is disposed outside the display region. The display device also includes a bus line that supplies a voltage to the peripheral driving circuit and a reflection pixel electrode disposed for each of the display pixels. A wiring layer of the reflection pixel electrode includes a portion of the peripheral driving circuit or a portion of the bus line.
REFERENCES:
patent: 5751381 (1998-05-01), Ono et al.
patent: 6239779 (2001-05-01), Furuya et al.
Miyajima Yasushi
Yokoyama Ryoichi
Dinh Trinh Vo
Morrison & Foerster / LLP
Sanyo Electric Company Ltd.
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