Voltage programmed pixel circuit, display system and driving method thereof

• US 9,373,645 B2
• Filed: 01/17/2014
• Issued: 06/21/2016
• Est. Priority Date: 01/28/2005
• Status: Active Grant

• Current Assignee: IGNIS Innovation Incorporated
• Original Assignee: IGNIS Innovation Incorporated
• Inventors: Nathan, Arokia, Chaji, Gholamreza, Servati, Peyman
• Primary Examiner(s): ABDIN, SHAHEDA A
• Application Number:
  US14/157,699
• Publication Number:
  US 20140132581A1
• Time in Patent Office: 886 Days
• Field of Search: 345 76- 82, 345/90, 345/92, 345/93, 345/99, 345/100, 345/204, 345/206, 345/214, 345 42- 43
• US Class Current: 1/1
• CPC Class Codes: G09G 2300/0465 Improved aperture ratio, e.g. by size reduction of the pixel circuit, e.g. for improving the pixel density or the maximum displayable luminance or brightness
• 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 2300/0866 by means of changes in the pixel supply voltage
• CPC Class Codes: G09G 2310/08 Details of timing specific for flat panels, other than clock recovery
• CPC Class Codes: G09G 2320/043 Preventing or counteracting the effects of ageing
• CPC Class Codes: G09G 3/3233 with pixel circuitry controlling the current through the light-emitting element
• 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 5/00 Control arrangements or circuits for visual indicators common to cathode-ray tube indicators and other visual indicators image data processing or generation, in general G06T
• 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: H10K 59/131 Interconnections, e.g. wiring lines or terminals

Abstract

A voltage programmed pixel circuit, display system having the pixel circuit and driving method thereof is provided. The pixel circuit includes a light emitting device, a driving transistor connected to the light emitting device and a programming circuit. The programming circuit adjusts a pixel current during a programming cycle of the pixel circuit.

Claims

1. A method of programming a pixel circuit including a driving section having a drive transistor and an emissive device and a programming section having a programming transistor, the method comprising:

the programming transistor converting its gate-source voltage to a programming current, the programming transistor operating as a stable local reference transistor to supply the programming current as a local current source to the drive transistor;

the programming current adjusting a gate-source voltage of the drive transistor; and

the driving section driving the emissive device with a drive current related to the programming current and causing the emissive device to emit light according to at least the programming current while the programming transistor remains off, such that the drive current is independent of aging effects of the drive transistor and of the emissive device,

wherein the programming transistor is on for a small fraction of time during a frame and is off during the rest of the frame including the entire time the driving section is driving the emissive device, and wherein the emissive device is off during a programming cycle of the pixel circuit.

2. The method of claim 1, wherein during the programming cycle in which programming information is transferred to the programming section for causing the emissive device to emit light according to at least the programming information, a bias voltage is provided to a node in the programming section to cause a voltage at a node in the driving section to be related to the bias voltage, the programming information, a threshold voltage of the programming transistor, and a threshold voltage of the drive transistor.

3. The method of claim 2, wherein during a driving cycle in which the driving section drives the emissive device immediately following the programming cycle, a voltage at the node in the driving section goes to a voltage of the emissive device while the gate-source voltage of the drive transistor is adjusted by the programming current.