Display device and driving method thereof

Patent metadata

Field	Value
Publication number	US-9443471-B2
Application number	US-201314411374-A
Country	US
Kind code	B2
Filing date	Jul 24, 2013
Priority date	Jul 31, 2012
Publication date	Sep 13, 2016
Grant date	Sep 13, 2016

Abstract

A gate driver divides n scanning lines (G 1 to Gn) into p blocks (BL 1 to BLp), and provides for each block, a common selection period for selecting a whole or a part of k scanning lines included in the block, and a scanning period for sequentially selecting k scanning lines included in the block. A source driver ( 30 ) detects a characteristic of a driving transistor via a data line from a pixel circuit ( 11 ) corresponding to a scanning line that is being selected in the common selection period, and supplies to the data line a corrected data voltage that has been obtained by correcting the data voltage based on the detected characteristic of the driving transistor. Accordingly, there is provided a display device that can compensate for a characteristic variation of the driving transistor while solving a shortage of writing time.

First claim

The invention claimed is:

1. An active matrix-type display device comprising:
a display unit including a plurality of data lines, a plurality of scanning lines, and a plurality of pixel circuits disposed corresponding to the plurality of data lines and the plurality of scanning lines;
a data driving unit connected to the plurality of data lines; and
a scanning driving unit connected to the plurality of scanning lines,
wherein the pixel circuit includes:
an electro-optic element driven by a current; and
a driving transistor that is provided in series with the electro-optic element and that controls a driving current to be supplied to the electro-optic element, in accordance with a voltage supplied via the data line,

the scanning driving unit makes each of the scanning lines correspond to any one of one or more blocks, and provides, for each block, a common selection period for selecting a whole or a part of scanning lines corresponding to the block, and a scanning period for sequentially selecting the scanning lines corresponding to the block,
the data driving unit includes:
a detecting unit that detects a characteristic of the driving transistor via the data line from a pixel circuit corresponding to a scanning line which is being selected in the common selection period; and
a correction output unit that supplies to the data line a voltage obtained by correcting a data voltage indicating gradation data, based on a characteristic of the driving transistor detected by the detecting unit in the common selection period immediately before the scanning period, and

the scanning driving unit sequentially shifts each block in a unit of scanning lines whose number is smaller than a maximum number of scanning lines corresponding to each block, in each period of a length not smaller than one frame period as a length approximately equal to a sum of the common selection period and the scanning period that are provided in each block.

2. The display device according to claim 1 , wherein
the scanning driving unit makes each of the scanning lines correspond to any one of a plurality of blocks, and
the scanning lines corresponding to each block are sequentially arranged in an extending direction of the data line.

3. The display device according to claim 1 , wherein
the scanning driving unit sequentially shifts, in the each one frame period, each block in a unit of scanning lines whose number is obtained by dividing a maximum number of scanning lines corresponding to each block by N, using N frame periods (N is an integer not smaller than two and smaller than a maximum number of scanning lines corresponding to each block) as one cycle.

4. The display device according to claim 1 , wherein
each of the detecting unit and the correction output unit is provided for each of the data lines.

5. The display device according to claim 1 , wherein
each of the detecting unit and the correction output unit is provided for each predetermined number of two or more data lines, and
the display device further comprises a selector for connecting each of the detecting unit and the correction output unit to the predetermined number of data lines.

6. The display device according to claim 1 , wherein
the driving transistor is a thin-film transistor having a channel layer formed of an oxide semiconductor.

7. The display device according to claim 1 , wherein
an annealing process using laser light is performed to the driving transistor at a time of forming the driving transistor, and
the extending direction of the data line is along a direction of each scanning of the laser light in the annealing process.

8. The display device according to claim 1 , wherein
the pixel circuit further includes:
an input transistor that has a control terminal connected to the scanning line, and that becomes in an on state when the scanning line is being selected; and
a driving capacitor element that holds a voltage corresponding to a voltage supplied via the data line; and
a light emission control transistor that is provided in series with the electro-optic element, and that becomes in an off state at least when a scanning line corresponding to the pixel circuit is being selected,

the driving transistor controls the driving current corresponding to a voltage held by the driving capacitor element,
the detecting unit includes a correction capacitor element charged to a correction voltage corresponding to a characteristic of the driving transistor in the common selection period, and
the correction output unit supplies to the data line a voltage that is obtained by adding to the data voltage or by subtracting from the data voltage the correction voltage held by the correction capacitor element in the scanning period.

9. The display device according to claim 8 , wherein
a pixel circuit corresponding to a scanning line selected in the common selection period supplies a voltage corresponding to a threshold voltage of the driving transistor, from the input transistor in an on state to the detecting unit via the data line, and
the detecting unit gives, to one end of the correction capacitor element, a voltage supplied from the pixel circuit corresponding to the scanning line selected in the common selection period, and gives a first fixed voltage to the other end of the correction capacitor element.

10. The display device according to claim 9 , wherein
the detecting unit further includes a detection switch unit that connects the one end of the correction capacitor element to the data line and that gives the first fixed voltage to the other end of the correction capacitor element, in a detection period within the common selection period, and
the correction output unit includes:
a buffer amplifier having an input terminal connected to the one end of the correction capacitor element; and
a correction output switch unit that gives the data voltage to the other end of the correction capacitor element of the detecting unit, and that connects an output terminal of the buffer amplifier to the data line, in the scanning period.

11. The display device according to claim 10 , wherein
the data driving unit further includes a fixed voltage supply unit that is provided in each of the data lines, and that supplies a second fixed voltage to the data line in the common selection period and before the detection period.

12. The display device according to claim 8 , wherein
a pixel circuit corresponding to a scanning line selected in the common selection period supplies a driving current that flows to the driving transistor, from the input transistor in an on state to the detecting unit via the data line, and
the detecting unit gives, to one end of the correction capacitor element, a voltage corresponding to a threshold voltage of the driving transistor obtained based on the driving current supplied from the pixel circuit corresponding to the scanning line selected in the common selection period, and gives a first fixed voltage to the other end of the correction capacitor element.

13. The display device according to claim 12 , wherein
the detecting unit and the correction output unit include in common:
an operational amplifier having a inverting input terminal connected to the data line; and
a control switch that is provided between the inverting input terminal and an output terminal of the operational amplifier, and that is opened in the common selection period and is closed in the scanning period,

the detecting unit further includes:
a diode element that is provided in parallel with the control switch between the inverting input terminal and the output terminal of the operational ampl

Assignees

• Sharp Kk

Inventors

• Kishi Noritaka
• Ohara Masanori
• Noguchi Noboru

Classifications

• G09G3/3233

  with pixel circuitry controlling the current through the light-emitting element · CPC title

• G09G2320/043

  Preventing or counteracting the effects of ageing · CPC title

• G09G2310/0291

  Details of output amplifiers or buffers arranged for use in a driving circuit · CPC title

• G09G3/3291

  in which the data driver supplies a variable data voltage for setting the current through, or the voltage across, the light-emitting elements · CPC title

• G09G2310/0218

  with collection of electrodes in groups for n-dimensional addressing · CPC title