Computer graphics processing and selective visual display system – Plural physical display element control system – Display elements arranged in matrix
Reexamination Certificate
1998-08-31
2002-01-01
Shalwala, Bipin (Department: 2673)
Computer graphics processing and selective visual display system
Plural physical display element control system
Display elements arranged in matrix
C345S098000, C257S059000
Reexamination Certificate
active
06335716
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a semiconductor device and a semiconductor display device correcting system. Particularly, the present invention relates to a semiconductor display device in which a pixel, a driving circuit, and a peripheral circuit such as a nonvolatile memory are integrally formed on an insulating substrate by using an SOI (Silicon On Insulator) technique. Moreover, the present invention relates to a correcting method of a semiconductor display device. Silicon set forth in the present specification indicates single crystal or substantially single crystal.
2. Description of the Related Art
In recent years, a technique for manufacturing a semiconductor device, such as a thin film transistor (TFT), in which a semiconductor thin film is formed on an inexpensive glass substrate has been rapidly developed. The reason is that the demand for an active matrix type liquid crystal display device (liquid crystal panel) has increased.
The active matrix type liquid crystal panel is constructed such that a TFT is disposed for each of several tens to several millions of pixel regions arranged in matrix, and an electric charge going in and out of each pixel electrode is controlled by the switching function of the TFT.
FIG. 23
shows a conventional active matrix type liquid crystal display device. As shown in
FIG. 23
, the conventional active matrix type liquid crystal display device includes a source line side driver
2301
, a gate line side driver
2302
, a plurality of pixel TFTs
2303
arranged in matrix, and a picture signal line
2304
.
The source line side driver and the gate line side driver include a shift register, a buffer circuit, and the like, and are integrally formed on the same substrate as an active matrix circuit in recent years.
Thin film transistors using amorphous silicon formed on a glass substrate are disposed in the active matrix circuit.
There is also known a structure in which quartz is used for a substrate and a thin film transistor is formed of a polycrystalline silicon film. In this case, both a peripheral driving circuit and an active matrix circuit are constituted by thin film transistors formed on the quartz substrate.
There is also known a technique in which a thin film transistor using a crystalline silicon film is formed on a glass substrate by using a technique such as laser annealing. When this technique is used, an active matrix circuit and a peripheral driving circuit can be integrated on a glass substrate.
In the structure as shown in
FIG. 23
, a picture signal supplied to the picture signal line
2304
is selected by a signal from a shift register circuit of the source line side driver (shift register for horizontal scanning). Then the designated picture signal is supplied to the corresponding source signal line.
The picture signal supplied to the source signal line is selected by a thin film transistor of a pixel and is written into the designated pixel electrode.
The thin film transistor of the pixel is operated by a selection signal supplied from a shift register of the gate line side driver (shift register for vertical scanning) through a gate signal line.
This operation is sequentially repeated at suitable timing by signals from the shift register of the source line side driver and signals from the shift register of the gate line side driver, so that information is sequentially written into the respective pixels arranged in matrix.
In recent years, an active matrix type liquid crystal display device has been often used for a note-sized personal computer. In the personal computer, a liquid crystal display device is required to realize such functions that a plurality of application programs are concurrently started up or a picture from a digital camera is taken in and is processed, that is, a liquid crystal display device capable of realizing large screen, high resolution, and multi-gradation display is required.
Moreover, the demand for a liquid crystal projector which can project a television signal such as a high-definition television signal and can realize a large screen, has increased. In this case as well, the quality of a provided picture depends on the degree of fineness of gradation display.
As described above, for the purpose of providing a high quality picture, it is important to what degree the gradation display can be made fine. As a system of gradation display, there are a system (analog gradation) of supplying an analog signal such as a video signal or a television signal to a source line and a system (digital gradation) of supplying a digital signal from a personal computer or the like to a picture signal line.
In the analog gradation, as described above, analog picture signals to be supplied to the picture signal line are sequentially selected by signals from the source driver, and the designated picture signal is supplied to the corresponding source line.
In the digital gradation, digital signals to be supplied to the picture signal line are sequentially selected, and after D/A conversion, the designated picture signal is supplied to the corresponding source line.
In the case of the liquid crystal display device, even when any gradation display of the digital gradation and the analog gradation is used, the gradation display is realized by controlling the strength of transmitted light transmitting through the respective pixels of the liquid crystal panel by a voltage applied to the pixel. There is a relation between the voltage (V) applied to the pixel of the liquid crystal panel and the strength of transmitted light transmitting through the pixel as indicated by a dotted line in FIG.
24
. However, it should be noted that in this place, there is shown an example in which the liquid crystal display device is in a TN (twisted nematic) mode and uses a normally white mode in which the device becomes in a light state when a voltage is not applied.
As is understood from
FIG. 23
as well, there is a nonlinear relation between the voltage applied to the pixel of the liquid crystal panel and the strength of the transmitted light transmitting through the pixel. In other words, there is no linear relation between the voltage applied to the pixel and the strength of the transmitted light, so that it is difficult to control the strength of the transmitted light according to the applied voltage. Thus, it is difficult to realize desired gradation display.
In order to correct the above defect of the liquid crystal panel, a means called gamma correction is adopted. In the gamma correction, a voltage is corrected with respect to a supplied picture signal so that the strength of transmitted light is linearly changed according to an applied voltage. According to this gamma correction, excellent gradation display can be obtained. The relation between the applied voltage and the strength of the transmitted light in the case where the gamma correction is carried out is indicated by a solid line in FIG.
24
. As shown by the solid line in
FIG. 24
, when the gamma correction is applied to the picture signal, the relation between the applied voltage and the strength of the transmitted light becomes almost linear, so that it becomes possible to control the strength of the transmitted light according to the applied voltage, and excellent gradation display can be made.
However, conventionally, in order to apply the gamma correction to a picture signal, an IC circuit is additionally required, that is, a substrate having an IC circuit must be additionally provided on the outside of the liquid crystal panel. Thus, although excellent gradation display can be realized, increase of the number of parts is caused and it is actually impossible to miniaturize a product.
Moreover, in the active matrix type liquid crystal display device, from the nature of the device, its display characteristics become slightly different from every liquid crystal panel produced. However, conventionally, the same IC chip used for gamma correction and the same data stored in the IC chip have been used for all liquid
Koyama Jun
Yamazaki Shunpei
Nixon & Peabody LLP
Piziali Jeff
Robinson Eric J.
Semiconductor Energy Laboratory Co,. Ltd.
Shalwala Bipin
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