Display with current controlled light-emitting device

• US 20050269960A1
• Filed: 06/06/2005
• Published: 12/08/2005
• Est. Priority Date: 06/07/2004
• Status: Abandoned Application

• Current Assignee: InnoLux Corporation, Kyocera Corporation
• Original Assignee: Chi Mei Optoelectronics (InnoLux Corporation), Kyocera Corporation
• Inventors: Ono, Shinya, Kobayashi, Yoshinao, Miwa, Koichi
• Application Number:
  US11/144,662
• Publication Number:
  US 20050269960A1
• Time in Patent Office: Days
• US Class Current: 315/169.300
• 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 2310/08 Details of timing specific for flat panels, other than clock recovery
• CPC Class Codes: G09G 3/2011 by amplitude modulation
• CPC Class Codes: G09G 3/3233 with pixel circuitry controlling the current through the light-emitting element
• CPC Class Codes: G09G 3/3291 in which the data driver supplies a variable data voltage for setting the current through, or the voltage across, the light-emitting elements

Abstract

A display includes an electric current controlled light-emitting device that emits light with a luminance depending on an electric current flowing therethrough. The display also includes a transistor that has a gate electrode, a source electrode, and a drain electrode, and controls the electric current based on a data voltage between one of the source and drain electrodes and the gate electrode; and a controller that controls a gate-to-source voltage and a gate-to-drain voltage of the transistor based on a change in the luminance of the electric current controlled light-emitting device while maintaining the transistor element in a saturation region.

Claims

1. A display comprising:

an electric current controlled light-emitting device that emits light with a luminance depending on an electric current flowing therethrough;

a transistor that has a gate electrode, a source electrode, and a drain electrode, and controls the electric current based on a data voltage between one of the source and drain electrodes and the gate electrode; and

a controller that controls a voltage between the gate electrode and the source electrode and a voltage between the gate electrode and the drain electrode based on a change in the luminance of the electric current controlled light-emitting device while maintaining the transistor element in a saturation region.

2. The display according to claim 1, wherein

the controller controls the voltage between the gate electrode and the source electrode and the voltage between the gate electrode and the drain electrode so that a difference between the voltage between the gate electrode and the source electrode and a driving threshold voltage of the transistor is not more than a voltage between the drain electrode and the source electrode.

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

an electric current source that outputs a predetermined level of electric current source voltage to supply the electric current to the electric current controlled light-emitting device;

a data voltage supplying unit that generates the data voltage corresponding to a gradation level based on a predetermined reference voltage; and

a reference voltage generating unit that generates a reference voltage corresponding to the luminance;

wherein the controller controls the electric current source voltage and the reference voltage to control the voltage between the gate electrode and the source electrode and the voltage between the gate electrode and the drain electrode.

4. The display according to claim 3, wherein

the controller controls the electric current source voltage and the reference voltage based on a standard electric current source voltage and a standard reference voltage, the standard electric current source voltage indicating the electric current source voltage where the transistor is in the saturation region with the electric current controlled light-emitting device emitting light with a predetermined standard display luminance, the standard reference voltage indicating a reference voltage where the transistor is in the saturation region with the electric current controlled light-emitting device emitting light with the predetermined standard display luminance.

5. The display according to claim 4, wherein

the electric current controlled light-emitting device has an anode electrically connected to the electric current source, and a cathode electrically connected to the drain of the transistor, and

the standard electric current source voltage and the standard reference voltage are determined so that a difference between the standard electric currents source voltage and a maximum voltage applied between the anode and the cathode is not less than the standard reference voltage.

6. The display according to claim 5, wherein

the controller derives the electric current source voltage as a sum of the standard electric current source voltage and a differential voltage according to the luminance, and derives the reference voltage as a sum of the standard reference voltage and a voltage obtained by division of the differential voltage by a circuit parameter determined based on a circuit structure around the transistor.

7. The display according to claim 1, further comprising:

a threshold voltage detecting unit that detects a driving threshold voltage of the transistor;

wherein

a voltage corresponding to a sum of the data voltage and the driving threshold voltage is applied between the gate electrode and the source electrode of the transistor.