Method and system for driving an active matrix display circuit

• US 9,058,775 B2
• Filed: 12/03/2013
• Issued: 06/16/2015
• Est. Priority Date: 01/09/2006
• Status: Active Grant

• Current Assignee: IGNIS Innovation Incorporated
• Original Assignee: IGNIS Innovation Incorporated
• Inventors: Nathan, Arokia, Chaji, Gholamreza
• Primary Examiner(s): Boddie, William
• Assistant Examiner(s): ELNAFIA, SAIFELDIN E
• Application Number:
  US14/095,583
• Publication Number:
  US 20140085168A1
• Time in Patent Office: 560 Days
• Field of Search: 345/76, 345/82
• US Class Current: 1/1
• CPC Class Codes: G09G 2300/0417 Special arrangements specific to the use of low carrier mobility technology
• CPC Class Codes: G09G 2300/0426 Layout of electrodes and connections
• CPC Class Codes: G09G 2300/043 Compensation electrodes or other additional electrodes in matrix displays related to distortions or compensation signals, e.g. for modifying TFT threshold voltage in column driver
• CPC Class Codes: G09G 2300/0809 Several active elements per pixel in active matrix panels
• 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 2300/0861 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 2310/0251 Precharge or discharge of pixel before applying new pixel voltage
• CPC Class Codes: G09G 2310/0254 Control of polarity reversal in general, other than for liquid crystal displays
• CPC Class Codes: G09G 2310/0262 The addressing of the pixel, in a display other than an active matrix LCD, involving the control of two or more scan electrodes or two or more data electrodes, e.g. pixel voltage dependent on signals of two data electrodes
• CPC Class Codes: G09G 2310/061 for resetting or blanking
• CPC Class Codes: G09G 2310/066 Waveforms comprising a gently increasing or decreasing portion, e.g. ramp
• CPC Class Codes: G09G 2320/029 by monitoring one or more pixels in the display panel, e.g. by monitoring a fixed reference pixel
• CPC Class Codes: G09G 2320/043 Preventing or counteracting the effects of ageing
• CPC Class Codes: G09G 2320/045 Compensation of drifts in the characteristics of light emitting or modulating elements
• 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 method and system for driving an active matrix display is provided. The system includes a drive circuit for a pixel having a light emitting device. The drive circuit includes a drive transistor for driving the light emitting device. The system includes a mechanism for adjusting the gate voltage of the drive transistor.

Claims

1. A display system, comprising:

a pixel circuit for operating a light emitting device to emit light according to programming information, the pixel circuit including;

a drive transistor connected in series to the light emitting device, the drive transistor including a gate terminal, a first terminal and a second terminal,

a first switch transistor including a gate terminal, a first terminal and a second terminal, the gate terminal of the first switch transistor being connected to a select line for operating the first switch transistor, the first terminal of the first switch transistor being connected to a data line providing a programming voltage according to the programming information during a programming cycle, the second terminal of the first switch transistor being connected to the gate terminal of the drive transistor, and

a circuit for adjusting the gate voltage of the drive transistor by at least partially discharging the voltage on the gate terminal of the drive transistor through a discharge component having a resistance that varies as the pixel circuit ages, and

a controller for operating the data line and the select line to drive the pixel circuit such that;

the programming voltage is provided on the data line during the programming cycle to thereby charge the gate terminal of the drive transistor with the programming voltage via the first switch transistor, and

the programming voltage is at least partially discharged through the discharge component during a frame that includes a compensation cycle following the programming cycle while the first switch transistor is turned off, and

the pixel circuit is driven to emit light during a driving cycle according to the voltage remaining on the gate terminal of the drive transistor following the at least partial discharge.

2. A display system, comprising:

a pixel circuit for operating a light emitting device to emit light according to programming information, the pixel circuit including;

a drive transistor connected in series to the light emitting device, the drive transistor including a gate terminal, a first terminal and a second terminal,

a first switch transistor including a gate terminal, a first terminal and a second terminal, the gate terminal of the first switch transistor being connected to a select line for operating the first switch transistor, the first terminal of the first switch transistor being connected to a data line providing a programming voltage according to the programming information during a programming cycle, the second terminal of the first switch transistor being connected to the gate terminal of the drive transistor, and

a circuit for adjusting the gate voltage of the drive transistor by at least partially discharging the voltage on the gate terminal of the drive transistor through a discharge component having a resistance that varies as the pixel circuit ages, and

a controller for operating the data line and the select line to drive the pixel circuit such that;

the programming voltage is provided on the data line during the programming cycle to thereby charge the gate terminal of the drive transistor with the programming voltage via the first switch transistor,

the pixel circuit is driven during a frame that includes the programming cycle to emit light during a driving cycle according to the current through the drive transistor,

a characteristic of the discharge component is extracted during an extraction cycle following the programming cycle during the frame, and

a luminance degradation of the pixel is compensated, using the extracted characteristic, by calibrating a programming voltage that is applied in another frame.