Display device and method for driving display device

Patent metadata

Field	Value
Publication number	US-2016012774-A1
Application number	US-201414771533-A
Country	US
Kind code	A1
Filing date	Feb 20, 2014
Priority date	Apr 2, 2013
Publication date	Jan 14, 2016
Grant date	—

Abstract

In a display device that has self light-emitting type display elements and that adopts time-division driving, power consumption is reduced over the conventional one. Each of emission lines is connected to the gate terminals of light-emission control transistors provided for organic EL elements of different light-emitting colors in three pixel circuits arranged side by side in an extension direction of scanning signal lines. When there is no change in image content throughout a period longer than or equal to a predetermined period during a time-division driving mode, an operating mode is switched to a pause driving mode. During the pause driving mode, emission drivers bring only first emission lines into a selected state, by which a still image with a ⅓ resolution of an image displayed during the time-division driving mode is displayed on a display unit. During a pause period, peripheral drivers go into a pause state.

First claim

1 . A display device comprising a display unit that includes pixel circuits arranged in a matrix form so as to form a plurality of rows and a plurality of columns, wherein
each of the pixel circuits includes j electro-optical elements of different light-emitting colors (j is an integer greater than or equal to 3), an operating mode is switchable between a time-division driving mode in which image display on the display unit is performed by dividing one frame period into j subframes and performing writing of image data to the pixel circuits on a subframe-by-subframe basis, and bringing, in each of the pixel circuits, electro-optical elements of different light-emitting colors into a light-emitting state on a subframe-by-subframe basis; and a pause driving mode in which still image display on the display unit is performed at a lower refresh rate than that for when in the time-division driving mode, by repeating a refresh period during which writing of image data to the pixel circuits is performed and a pause period during which the writing of image data to the pixel circuits is brought into a pause state, and when the operating mode is the pause driving mode, j pixel circuits are considered one group and electro-optical elements of different light-emitting colors in j pixel circuits included in each group are brought into a light-emitting state, by which a still image with a resolution not more than 1/j of a resolution of an image, that is displayed on the display unit when the operating mode is the time-division driving mode, is displayed on the display unit.

2 . The display device according to claim 1 , wherein
each of the pixel circuits further includes: j light-emission control transistors provided to have a one-to-one correspondence with the j electro-optical elements; and a drive current control unit configured to control a drive current for bringing the j electro-optical elements into a light-emitting state, the display unit includes j light-emission control lines for each row, in each of the pixel circuits, control terminals of the j light-emission control transistors are connected to different light-emission control lines, first conduction terminals of the j light-emission control transistors are connected to the drive current control unit, and second conduction terminals of the j light-emission control transistors are connected to corresponding electro-optical elements, when focusing on j pixel circuits included in each group and j light-emission control lines corresponding to the j pixel circuits, each of the focused j light-emission control lines is connected to control terminals of light-emission control transistors corresponding to electro-optical elements of different light-emitting colors in the focused j pixel circuits, when the operating mode is the time-division driving mode, for each row, the j light-emission control lines are sequentially brought into a selected state on a subframe-by-subframe basis, and when the operating mode is the pause driving mode, for each row, only one of the j light-emission control lines is brought into a selected state.

3 . The display device according to claim 2 , further comprising:
scanning signal lines disposed in the display unit so as to correspond to the respective rows; data lines disposed in the display unit so as to correspond to the respective columns; a first power supply line disposed in the display unit and configured to supply a high-level constant voltage to the pixel circuits; a second power supply line disposed in the display unit and configured to supply a low-level constant voltage to the pixel circuits; a scanning signal line drive circuit configured to drive the scanning signal lines; a data line drive circuit configured to drive the data lines; and a light-emission control line drive circuit configured to drive the light-emission control lines, wherein the drive current control unit includes: a drive transistor provided between the first power supply line and the second power supply line so as to be in series with each of the j light-emission control transistors, and configured to control the drive current; an input transistor provided between a control terminal of the drive transistor and a corresponding one of the data lines, and configured to electrically connect the control terminal of the drive transistor to the corresponding one of the data lines when a corresponding one of the scanning signal lines is brought into a selected state by the scanning signal line drive circuit; and a capacitor provided between the control terminal of the drive transistor and one conduction terminal of the drive transistor, during the refresh period, the light-emission control line drive circuit brings, for each row, only one of the j light-emission control lines into a selected state, the scanning signal line drive circuit sequentially brings the scanning signal lines disposed in the display unit into a selected state, and the data line drive circuit applies data voltages according to a still image to be displayed on the display unit during the pause driving mode, to the data lines, according to each of the scanning signal lines going into a selected state, and during the pause period, the light-emission control line drive circuit keeps the light-emission control line brought into the selected state during the refresh period, in the selected state and keeps other light-emission control lines in a non-selected state, and the scanning signal line drive circuit and the data line drive circuit go into a pause state.

4 . The display device according to claim 2 , further comprising:
scanning signal lines disposed in the display unit so as to correspond to the respective rows; data lines disposed in the display unit so as to correspond to the respective columns; a first power supply line disposed in the display unit and configured to supply a high-level constant voltage to the pixel circuits; a second power supply line disposed in the display unit and configured to supply a low-level constant voltage to the pixel circuits; a reference voltage line disposed in the display unit and configured to supply a predetermined reference voltage to the pixel circuits; a scanning signal line drive circuit configured to drive the scanning signal lines; a data line drive circuit configured to drive the data lines; and a light-emission control line drive circuit configured to drive the light-emission control lines, wherein the drive current control unit includes: a drive transistor provided between the first power supply line and the second power supply line so as to be in series with each of the j light-emission control transistors, and configured to control the drive current; a reference voltage supply control transistor provided between a control terminal of the drive transistor and the reference voltage line, and configured to electrically connect the control terminal of the drive transistor to the reference voltage line when a corresponding one of the scanning signal lines is brought into a selected state by the scanning signal line drive circuit; an input transistor provided between one conduction terminal of the drive transistor and a corresponding one of the data lines, and configured to electrically connect the one conduction terminal of the drive transistor to the corresponding one of the data lines when the corresponding one of the scanning signal lines is brought into a selected state by the scanning signal line drive circuit; and a capacitor provided between the control terminal of the drive transistor and the one conduction terminal of the drive transistor, during the refresh period, the light-emission control line drive circuit brings, for each row, only one of the j light-emission control lines into a selected state, the scanning signal

Assignees

• Sharp Kk

Inventors

• Ohara Masanori
• Noguchi Noboru
• Kishi Noritaka

Classifications

• H10D30/6755

  Oxide semiconductors, e.g. zinc oxide, copper aluminium oxide or cadmium stannate · CPC title

• G09G3/3258

  with pixel circuitry controlling the voltage across the light-emitting element · CPC title

• G09G2300/0842

  forming a memory circuit, e.g. a dynamic memory with one capacitor · CPC title

• G09G2300/0814

  used for selection purposes, e.g. logical AND for partial update · CPC title

• G09G3/2025

  the sub-frames having all the same time duration · CPC title