EL display apparatus

• US 10,198,992 B2
• Filed: 12/29/2017
• Issued: 02/05/2019
• Est. Priority Date: 09/07/2001
• Status: Expired due to Term

• Current Assignee: JOLED Inc.
• Original Assignee: JOLED Inc.
• Inventors: Takahara, Hiroshi, Tsuge, Hitoshi
• Primary Examiner(s): Patel, Kumar
• Assistant Examiner(s): Bogale, Amen
• Application Number:
  US15/858,692
• Publication Number:
  US 20180144686A1
• Time in Patent Office: 403 Days
• CPC Class Codes: G09G 2300/0404 Matrix technologies
• CPC Class Codes: G09G 2300/0413 Details of dummy pixels or dummy lines in flat panels
• CPC Class Codes: G09G 2300/0809 Several active elements per pixel in active matrix panels
• CPC Class Codes: G09G 2300/0814 used for selection purposes, e.g. logical AND for partial update
• 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 2300/0852 being a dynamic memory with more than one capacitor
• CPC Class Codes: G09G 2300/0861 with additional control of the display period without amending the charge stored in a pixel memory, e.g. by means of additional select electrodes
• CPC Class Codes: G09G 2310/0205 Simultaneous scanning of several lines in flat panels
• CPC Class Codes: G09G 2310/0218 with collection of electrodes in groups for n-dimensional addressing
• CPC Class Codes: G09G 2310/0248 Precharge or discharge of column electrodes before or after applying exact column voltages
• 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 2310/027 Details of drivers for data electrodes, the drivers handling digital grey scale data, e.g. use of D/A converters
• CPC Class Codes: G09G 2310/0289 Details of voltage level shifters arranged for use in a driving circuit
• CPC Class Codes: G09G 2310/08 Details of timing specific for flat panels, other than clock recovery
• CPC Class Codes: G09G 2320/0247 Flicker reduction other than flicker reduction circuits used for single beam cathode-ray tubes
• CPC Class Codes: G09G 2320/0257 Reduction of after-image effects
• CPC Class Codes: G09G 2320/0261 in the context of movement of objects on the screen or movement of the observer relative to the screen
• CPC Class Codes: G09G 2320/043 Preventing or counteracting the effects of ageing
• CPC Class Codes: G09G 2320/06 : Adjustment of display parameters
• CPC Class Codes: G09G 2320/0606 : Manual adjustment
• CPC Class Codes: G09G 2320/0626 : for control of overall brightness
• CPC Class Codes: G09G 2320/0646 : Modulation of illumination source brightness and image signal correlated to each other
• CPC Class Codes: G09G 2320/0653 : Controlling or limiting the speed of brightness adjustment of the illumination source
• CPC Class Codes: G09G 3/2003 : Display of colours specific for liquid crystal displays G09G3/3607
• CPC Class Codes: G09G 3/2007 : Display of intermediate tones
• CPC Class Codes: G09G 3/32 : semiconductive, e.g. using light-emitting diodes [LED]
• CPC Class Codes: G09G 3/3233 : with pixel circuitry controlling the current through the light-emitting element
• CPC Class Codes: G09G 3/3241 : the current through the light-emitting element being set using a data current provided by the data driver, e.g. by using a two-transistor current mirror
• CPC Class Codes: G09G 3/325 : the data current flowing through the driving transistor during a setting phase, e.g. by using a switch for connecting the driving transistor to the data driver
• CPC Class Codes: G09G 3/3258 : with pixel circuitry controlling the voltage across the light-emitting element
• CPC Class Codes: G09G 3/3266 : Details of drivers for scan electrodes
• CPC Class Codes: G09G 3/3275 : Details of drivers for data electrodes
• CPC Class Codes: G09G 5/02 : characterised by the way in which colour is displayed details of colour display specific for CRTs G09G1/28; specific for flat matrix panels other than liquid crystal displays G09G3/2003; specific for liquid crystal displays G09G3/3607
• CPC Class Codes: H01L 27/124 : with a particular composition, shape or layout of the wiring layers specially adapted to the circuit arrangement, e.g. scanning lines in LCD pixel circuits wiring structures per se H01L23/52
• CPC Class Codes: H01L 27/1251 : comprising TFTs having a different architecture, e.g. top- and bottom gate TFTs
• CPC Class Codes: H01L 27/1255 : integrated with passive devices, e.g. auxiliary capacitors
• CPC Class Codes: H01L 27/127 : with a particular formation, treatment or patterning of the active layer specially adapted to the circuit arrangement
• CPC Class Codes: H01L 27/156 : two-dimensional arrays
• CPC Class Codes: H01L 29/78645 : with multiple gate
• CPC Class Codes: H01L 29/78672 : Polycrystalline or microcrystalline silicon transistor
• CPC Class Codes: H01L 33/56 : Materials, e.g. epoxy or silicone resin
• CPC Class Codes: H01L 33/58 : Optical field-shaping elements
• CPC Class Codes: H05K 999/99 : dummy group
• CPC Class Codes: H10K 50/8428 : Vertical spacers, e.g. arranged between the sealing arrangement and the OLED
• CPC Class Codes: H10K 50/844 : Encapsulations
• CPC Class Codes: H10K 50/846 : comprising getter material or desiccants
• CPC Class Codes: H10K 50/86 : Arrangements for improving contrast, e.g. preventing reflection of ambient light
• CPC Class Codes: H10K 59/12 : Active-matrix OLED [AMOLED] displays
• CPC Class Codes: H10K 59/1213 : the pixel elements being TFTs
• CPC Class Codes: H10K 59/1216 : the pixel elements being capacitors
• CPC Class Codes: H10K 59/126 : Shielding, e.g. light-blocking means over the TFTs
• CPC Class Codes: H10K 59/35 : comprising red-green-blue [RGB] subpixels
• CPC Class Codes: H10K 59/352 : the areas of the RGB subpixels being different

Abstract

An electroluminescent (EL) display apparatus and method of controlling are provided. A display screen includes gate signal lines and source signal lines. A pixel corresponds to each intersection of the gate and source signal lines. Each pixel includes: an EL device including an anode and cathode terminals; a driving transistor to flow a current to the EL device; a first switch transistor provided on a current path through which the current flows from a power line through the driving transistor to the EL device; a second switch transistor to supply, to the driving transistor, an image signal from one of the source signal lines; and a third switch transistor provided between the anode terminal of the EL device and a voltage line. The voltage line is configured to supply a reverse bias voltage for reverse biasing the anode terminal of the EL device.

Claims

1. An electroluminescent (EL) display apparatus, comprising:

a display screen including;

a plurality of first gate signal lines;

a plurality of second gate signal lines;

a plurality of source signal lines; and

a plurality of pixels arranged in a matrix, each pixel corresponding to an intersection of the plurality of first gate signal lines and the plurality of source signal lines; and

a gate driver circuit including a first gate driver circuit connected to the plurality of first gate signal lines and a second gate driver circuit connected to the plurality of second gate signal lines,

wherein each pixel includes;

an EL device including an anode terminal and a cathode terminal;

a driving transistor to flow a current to the EL device;

a first switch transistor provided on a current path through which the current flows from a power line through the driving transistor to the EL device, the first switch transistor being controlled by the first gate driver circuit;

a second switch transistor to supply, to the driving transistor, an image signal supplied from one of the plurality of source signal lines; and

a third switch transistor provided between the anode terminal of the EL device and a voltage line, the third switch transistor being controlled by the second gate driver circuit, the voltage line being configured to supply a reverse bias voltage for reverse biasing the anode terminal of the EL device,

the first switch transistor is configured to be controlled in an OFF state by the first gate driver circuit, when the second gate driver circuit controls the third switch transistor in a state for reverse biasing the anode terminal of the EL device, and

the first gate driver circuit is configured to turn the first switch transistor from an ON state to the OFF state, and, after a lapse of time, the second gate driver circuit is configured to turn the third switch transistor from an OFF state to an ON state for reverse biasing the anode terminal of the EL device.

2. The EL display apparatus according to claim 1, further comprising:

a source driver circuit connected to the plurality of source signal lines,

wherein the source driver circuit is configured to supply a signal voltage to a gate of the driving transistor to flow a current which is N times as large as a predetermined value to the EL device to achieve a gray scale display indicated by the image signal, and

N is greater than one.

3. The EL display apparatus according to claim 1, further comprising:

a precharge circuit or a discharge circuit which forcibly charges or discharges the one of the plurality of source signal lines.

4. The EL display apparatus according to claim 1,

wherein the second gate driver circuit is configured to turn the third switch transistor from the ON state for reverse biasing the anode terminal of the EL device to the OFF state, and, after a second lapse of time, the first gate driver circuit is configured to turn the first switch transistor from the OFF state to the ON state.

5. The EL display apparatus according to claim 1,

wherein the first gate driver circuit is configured to select a plurality of the first gate signal lines simultaneously.

6. The EL display apparatus according to claim 1,

wherein the first gate signal lines are divided into a plurality of blocks,

a plurality of first gate signal lines in one block are connected as one control line, and

the first gate driver circuit is configured to select the plurality of first gate signal lines as a block simultaneously.

7. An electronic device, comprising:

the EL display apparatus according to claim 1.

8. A method of controlling an electroluminescent (EL) display apparatus,

the EL display apparatus including:

a display screen including;

first gate signal lines, the first gate signal lines being divided into a plurality of blocks, a plurality of the first gate signal lines in one block being connected as one control line;

second gate signal lines;

a plurality of source signal lines; and

a plurality of pixels arranged in a matrix, each pixel corresponding to an intersection of the first gate signal lines and the plurality of source signal lines; and

a gate driver circuit including a first gate driver circuit connected to the first gate signal lines and a second gate driver circuit connected to the second gate signal lines,

wherein each pixel includes;

an EL device including an anode terminal and a cathode terminal;

a driving transistor to flow a current to the EL device;

a first switch transistor provided on a current path through which the current flows from a power line through the driving transistor to the EL device;

a second switch transistor to supply, to the driving transistor, an image signal supplied from one of the plurality of source signal lines; and

a third switch transistor provided between the anode terminal of the EL device and a voltage line, the voltage line configured to supply a reverse bias voltage for reverse biasing the anode terminal of the EL device;

the method comprising;

controlling the first switch transistor via the first gate driver circuit;

selecting the plurality of first gate signal lines via the first gate driver circuit as a block simultaneously; and

controlling, via the second gate driver circuit, the third switch transistor to be in an ON state for reverse biasing the anode terminal of the EL device.

9. The method according to claim 8, further comprising:

controlling the first switch transistor to be in an OFF state via the first gate driver circuit, when the second gate driver circuit controls the third switch transistor to be in the ON state for reverse biasing the anode terminal of the EL device.

10. An electroluminescent (EL) display apparatus, comprising:

a display screen including;

a plurality of first gate signal lines;

a plurality of second gate signal lines;

a plurality of source signal lines; and

a plurality of pixels arranged in a matrix, each pixel corresponding to an intersection of the plurality of first gate signal lines and the plurality of source signal lines; and

a gate driver circuit including a first gate driver circuit connected to the plurality of first gate signal lines and a second gate driver circuit connected to the plurality of second gate signal lines,

wherein each pixel includes;

an EL device including an anode terminal and a cathode terminal;

a driving transistor to flow a current to the EL device;

a first switch transistor provided on a current path through which the current flows from a power line through the driving transistor to the EL device, the first switch transistor being controlled by the first gate driver circuit;

a second switch transistor to supply, to the driving transistor, an image signal supplied from one of the plurality of source signal lines; and

a third switch transistor provided between the anode terminal of the EL device and a voltage line, the third switch transistor being controlled by the second gate driver circuit, the voltage line being configured to supply a reverse bias voltage for reverse biasing the anode terminal of the EL device,

the first switch transistor is configured to be controlled in an OFF state by the first gate driver circuit, when the second gate driver circuit controls the third switch transistor in a state for reverse biasing the anode terminal of the EL device, and

the second gate driver circuit is configured to turn the third switch transistor from an ON state for reverse biasing the anode terminal of the EL device to an OFF state, and, after a lapse of time, the first gate driver circuit is configured to turn the first switch transistor from the OFF state to an ON state.

11. The EL display apparatus according to claim 10, further comprising:

a source driver circuit connected to the plurality of source signal lines,

wherein the source driver circuit is configured to supply a signal voltage to a gate of the driving transistor to flow a current which is N times as large as a predetermined value to the EL device to achieve a gray scale display indicated by the image signal, and

N is greater than one.

12. The EL display apparatus according to claim 10, further comprising:

a precharge circuit or a discharge circuit which forcibly charges or discharges the one of the plurality of source signal lines.

13. The EL display apparatus according to claim 10,

wherein the first gate driver circuit is configured to select a plurality of the first gate signal lines simultaneously.

14. The EL display apparatus according to claim 10,

wherein the first gate signal lines are divided into a plurality of blocks,

a plurality of first gate signal lines in one block are connected as one control line, and

the first gate driver circuit is configured to select the plurality of first gate signal lines as a block simultaneously.

15. An electronic device, comprising:

the EL display apparatus according to claim 10.