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US 5,650,636 AGranted
Active matrix display and electrooptical device
AssigneeSemiconductor Energy Laboratory Co., Ltd.
InventorsYasuhiko Takemura, Toshiji Hamatani, Toshimitsu Konuma, Jun Koyama, Yuji Kawasaki, Hongyong Zhang, Shunpei Yamazaki
Life of this patent
Estimating the term…
Abstract
A structure for reducing the OFF current of an active matrix display. In the active matrix display, plural TFTs are connected in series with each one pixel electrode. Of these TFTs connected in series, at least one TFT excluding the TFTs located at opposite ends is maintained in conduction. Alternatively, at least one capacitor is connected between the junction of the drain and source of each TFT connected in series and an AC grounded point. Thus, the amount of electric charge released from auxiliary capacitors during cutoff of the TFTs is reduced.
Claims28
An active matrix display comprising:
- pixel electrodes arranged in rows and columns;
- semiconductor film islands, each one of said islands being provided for each one of said pixel electrodes, said islands having N- or P-type regions;
- and
- at least three gate electrodes provided on each one of said semiconductor film islands and coated with an anodic oxide film to provide at least three thin film transistors on said each one of said semiconductor film islands, said three thin film transistors having three gate electrodes respectively, said three thin film transistors being connected in series with each other with gates of two of said three thin film transistors being connected with a gate signal line, and a gate of the other of said three thin film transistors being connected with a capacitor line,
- wherein one of source and drain of the other of said three thin film transistors is connected with one of source and drain of one of said two of said three thin film transistors, and the other of the source and drain of the other of said three thin film transistors is connected with one of source and drain of the other of said two of said three thin film transistors, and the other of the source and drain of said one of said two of said three thin film transistors is connected with an image signal line, and the other of the source and drain of the other of said two of said three thin film transistors is connected with the corresponding one of said pixel electrodes, and
- wherein said gate connected with said capacitor line is applied with a signal which activates said gate connected with said capacitor line at least for a major portion of a time during which a select signal is not applied to the gate signal line.
3 more elements
An active matrix display comprising:
- at least one pixel region arranged in a matrix form, said pixel region including a pixel electrode;
- a first line arranged in a substantially horizontal direction;
- at least two of first thin-film transistors provided in said pixel region, said at least two of first transistors having at least two gate electrodes respectively, said two gate electrodes being connected to said first line;
- a second line arranged in parallel to said first line;
- and
- at least one of second thin-film transistor provided in said pixel region, a gate electrode of said second transistor being connected to said second line,
- wherein one of source and drain of said second thin-film transistor is connected with one of source and drain of one of said first thin-film transistors, and the other of the source and drain of said second thin-film transistor is connected with one of source and drain of the other of said first thin-film transistors, and the other of the source and drain of said one of said first thin-film transistors is connected with said pixel electrode, and the other of the source and drain of the other of said first thin-film transistors is connected with an image signal line.
4 more elements
An active matrix display comprising:
- at least one pixel region arranged in a matrix form, said pixel region including a pixel electrode;
- a first line arranged in a substantially horizontal direction;
- at least two of first thin-film transistors provided in said pixel region, said at least two of first transistors having at least two gate electrodes respectively,, said two gate electrodes being connected to said first line;
- a second line arranged in parallel to said first line;
- and
- at least one of second thin-film transistor provided in said pixel region, a gate electrode of said second transistor being connected to said second line,
- wherein said second transistor has an offset gate structure that said gate electrode of said second transistor aparts from source and drain regions of said second transistor,
- wherein one of source and drain of said second thin-film transistor is connected with one of source and drain of one of said first thin-film transistors, and the other of the source and drain of said second thin-film transistor is connected with one of source and drain of the other of said first think-film transistors, and the other of the source and drain of said one of said first thin-film transistors is connected with said pixel electrode, and the other of the source and drain of the other of said first thin-film transistors is connected with an image signal line.
5 more elements
An active matrix display comprising:
- at least one pixel region arranged in a matrix form, said pixel region including a pixel electrode;
- a first line arranged in a substantially horizontal direction;
- at least two of first thin-film transistors provided in said pixel region, said at least two of first transistor having at least two gate electrodes respectively, said two gate electrodes being connected to said first line;
- a second line arranged in parallel to said first line;
- and
- at least one of second thin-film transistor provided in said pixel region, a gate electrode of said second transistor being connected to said second line,
- wherein ions are lightly doped into at least one portion of a channel region of said second transistor,
- wherein one of source and drain of said second thin-film transistor is connected with one of source and drain of one of said first thin-film transistors, and the other of the source and drain of said second thin-film transistor is connected with one of source and drain of the other of said first thin-film transistors, and the other of the source and drain of said one of said first thin-film transistors is connected with said pixel electrode, and the other of the source and drain of the other of said first thin-film transistors is connected with an image signal line.
5 more elements
An active matrix display comprising:
- at least one pixel region arranged in a matrix form, said pixel region including a pixel electrode;
- gate signal lines arranged in columns;
- image signal lines arranged in rows;
- capacitor lines arranged in parallel to said gate signal lines;
- at least two of first thin-film transistors provided in said pixel region and having at least two gate electrodes respectively, said two gate electrodes being connected to said gate signal line;
- and
- a capacitor connected between said two first transistors, said capacitor being constituted of a second thin-film transistor having a gate electrode connected with said capacitor line,
- wherein one of source and drain of said second thin-film transistor is connected with one of source and drain of one of said first thin-film transistors, and the other of the source and drain of said second thin-film transistor is connected with one of source and drain of the other of said first thin-film transistors, and the other of the source and drain of said one of said first thin-film transistors is connected with said pixel electrode, and the other of the source and drain of the other of said first thin-film transistors is connected with said image signal line.
5 more elements
An active matrix display comprising:
- at least one pixel region arranged in a matrix form, said pixel region including a pixel electrode;
- gate signal lines arranged in columns;
- image signal lines arranged in rows;
- capacitor lines arranged in parallel to said gate signal lines;
- at least two of first thin-film transistors provided in said pixel region and having at least two gate electrodes respectively, said two gate electrodes being connected to said gate signal line;
- a first capacitor connected between said two first transistors;
- said capacitor being constituted of a second thin-film transistor having a gate electrode connected with said capacitor line;
- and
- a second capacitor connected to said pixel electrode,
- wherein one of source and drain of said second thin-film transistor is connected with one of source and drain of one of said first thin-film transistors, and the other of the source and drain of said second thin-film transistor is connected with one of source and drain of the other of said first thin-film transistors, and the other of the source and drain of said one of said first thin-film transistors is connected with said pixel electrode, and the other of the source and drain of the other of said first thin-film transistors is connected with said image signal line.
7 more elements
An active matrix display comprising:
- pixel electrodes arranged in a matrix form;
- gate signal lines arranged in columns;
- image signal lines arranged in rows;
- capacitor lines arranged in parallel to said gate signal lines;
- a plurality of first thin-film transistors formed between said capacitor line and gate line, each of said first thin-film transistors having a gate electrode connected with said gate signal line;
- a capacitor formed with said capacitor line, said capacitor being constituted of a second thin-film transistor having a gate electrode connected with said capacitor line,
- wherein one of source and drain of said second thin-film transistor is connected with one of source and drain of one of said first thin-film transistors connected with said image signal line, and the other of the source and drain of said second thin-film transistor is connected with one of source and drain of another of said first thin-film transistors connected with said pixel electrode.
4 more elements
An active matrix display comprising:
- at least one pixel region arranged in a matrix form, said pixel region including a pixel electrode;
- a first line arranged in a substantially horizontal direction;
- at least two of first thin-film transistors each including a source region, a drain region and a channel region and provided in said pixel region, said at least two of first transistors having at least two gate electrodes respectively, said two gate electrodes being connected to said first line;
- a second line arranged in parallel to said first line;
- and
- an image signal line arranged in a substantially vertical direction;
- at least one of second thin-film transistor provided in said pixel region, a gate electrode of said second transistor being connected to said second line;
- wherein one of source and drain of said second thin-film transistor is connected with one of source and drain of one of said first thin-film transistors, and the other of the source and drain of said second thin-film transistor is connected with one of source and drain of the other of said first thin-film transistors, and the other of the source and drain of the other of said first thin-film transistors is connected with an image signal line, and
- wherein said channel region is extended in parallel to said image signal line and positioned below said image signal line.
6 more elements
Dependencies are inferred from the claim text.