Drive method of display device

• US 20100309186A1
• Filed: 05/12/2010
• Published: 12/09/2010
• Est. Priority Date: 06/03/2009
• Status: Abandoned Application

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Uchino, Katsuhide, Minami, Tetsuo
• Application Number:
  US12/662,924
• Publication Number:
  US 20100309186A1
• Time in Patent Office: Days
• US Class Current: 345/211
• CPC Class Codes: G09G 2300/0426 Layout of electrodes and connections
• CPC Class Codes: G09G 2300/0439 Pixel structures
• CPC Class Codes: G09G 2300/0819 used for counteracting undesired variations, e.g. feedback or autozeroing
• CPC Class Codes: G09G 2300/0842 forming a memory circuit, e.g. a dynamic memory with one capacitor
• CPC Class Codes: G09G 2300/0866 by means of changes in the pixel supply voltage
• CPC Class Codes: G09G 2310/0251 Precharge or discharge of pixel before applying new pixel voltage
• CPC Class Codes: G09G 2310/0256 with the purpose of reversing the voltage across a light emitting or modulating element within a pixel
• CPC Class Codes: G09G 2310/0291 Details of output amplifiers or buffers arranged for use in a driving circuit
• CPC Class Codes: G09G 2320/043 Preventing or counteracting the effects of ageing
• CPC Class Codes: G09G 2330/028 Generation of voltages supplied to electrode drivers in a matrix display other than LCD
• CPC Class Codes: G09G 3/3233 with pixel circuitry controlling the current through the light-emitting element
• CPC Class Codes: G09G 3/3266 Details of drivers for scan electrodes

Abstract

A drive method of a display device includes the steps of: performing threshold voltage cancel processing at least once, which changes a potential of a second node of a display device toward a potential obtained by subtracting a threshold voltage of a drive transistor from a potential of a first node by applying a given drive voltage to one source/drain region of the drive transistor from a feeding line while maintaining the potential of the first node; and then, performing writing processing which applies a video signal to the first node from a data line through a write transistor, wherein the sum of lengths of periods in which the threshold voltage cancel processing is performed is so set as to be shorter as a frame frequency becomes higher.

Claims

1. A drive method of a display device, which uses the display device including

(1) the total N×

M pieces of display elements in which N-pieces in a first direction and M-pieces in a second direction different from the first direction are arranged in a two-dimensional matrix state, each having a current-drive type light emitting portion and a drive circuit,

(2) M-pieces of scanning lines extending in the first direction,

(3) N-pieces of data lines extending in the second direction and

(4) M-pieces of feeding lines extending in the first direction,

in which the drive circuit includes a write transistor, a drive transistor and a capacitor unit,

in the display element of the m-th row (m=1, 2 . . . , M) and the n-th column (n=1, 2 . . . , N)

in the drive transistor,

(A-1) one source/drain region is connected to the m-th feeding line,

(A-2) the other source/drain region is connected to one end of the light emitting portion as well as connected to one electrode of the capacitor unit, which configures a second node, and

(A-3) a gate electrode is connected to the other source/drain region of the write transistor as well as connected to the other electrode of the capacitor unit, which configures a first node,

in the write transistor,

(B-1) one source/drain region is connected to the n-th data line, and

(B-2) the gate electrode is connected to the m-th scanning line, the drive method comprising the steps of;

(a) performing threshold voltage cancel processing at least once, which changes a potential of the second node toward a potential obtained by subtracting a threshold voltage of the drive transistor from a potential of the first node by applying a given drive voltage to one source/drain region of the drive transistor from the feeding line while maintaining the potential of the first node; and

then,

(b) performing writing processing which applies a video signal to the first node from the data line through the write transistor,

wherein the sum of lengths of periods in which the threshold voltage cancel processing is performed is so set as to be shorter as a frame frequency becomes higher.

2. The drive method of the display device according to claim 1,

wherein TU(FR₁)·

P(FR₁)>

TU(FR₂)·

P(FR₂) is satisfied,

in the case where the display device is driven by a given frame frequency FR, when the number of times the threshold voltage cancel processing is performed is represented as P(FR), a length of a period during which one threshold voltage cancel processing is performed is represented as TU(FR), and a first frame frequency is represented as FR₁ and a second frame frequency which is higher than the first frame frequency is FR₁ is represented as FR₂.

3. The drive method of the display device according to claim 1,

wherein pre-processing initializing the potential of the first node and the potential of the second node is performed,

subsequently, the step (a) and the step (b) are performed,

after that, the write transistor is turned off by a scanning signal from the scanning line to thereby allow the first node to be in a floating state, and electric current corresponding to a value of voltage difference between the first node and the second node is allowed to flow into the light emitting portion through the drive transistor in a state in which the given drive voltage is applied to one source/drain region of the drive transistor from the feeding line to thereby drive the light emitting portion.

4. The drive method of the display device according to claim 3,

wherein the light emitting portion includes an anode electrode and a cathode electrode,

the pre-processing is the step of setting the potential of the first node and the potential of the second node so that potential difference between the gate electrode and the other source/drain region of the drive transistor exceeds the threshold of the drive transistor as well as potential difference between the anode electrode and the cathode electrode of the light emitting portion does not exceed a threshold voltage of the light emitting portion.

5. The drive method of the display device according to claims 1,

wherein the light emitting portion is made of an organic electroluminescence light emitting portion.

6. The drive method of the display device according to claim 2,

wherein pre-processing initializing the potential of the first node and the potential of the second node is performed,

subsequently, the step (a) and the step (b) are performed,

after that, the write transistor is turned off by a scanning signal from the scanning line to thereby allow the first node to be in a floating state, and electric current corresponding to a value of voltage difference between the first node and the second node is allowed to flow into the light emitting portion through the drive transistor in a state in which the given drive voltage is applied to one source/drain region of the drive transistor from the feeding line to thereby drive the light emitting portion.