DISPLAY DRIVE APPARATUS AND DISPLAY APPARATUS

• US 20110134166A1
• Filed: 02/15/2011
• Published: 06/09/2011
• Est. Priority Date: 08/01/2006
• Status: Active Grant

• Current Assignee: Solas OLED Limited (Atlantic IP Services Limited)
• Original Assignee: Casio Computer Company Limited
• Inventors: SHIRASAKI, Tomoyuki, Ogura, Jun
• Granted Patent: US 8,339,427 B2
• Time in Patent Office: Days
• US Class Current: 345/690
• CPC Class Codes: G09G 2300/0842 forming a memory circuit, e.g. a dynamic memory with one capacitor
• CPC Class Codes: G09G 2300/0847 being a dynamic memory without any storage capacitor, i.e. with use of parasitic capacitances as storage elements
• CPC Class Codes: G09G 2300/0866 by means of changes in the pixel supply voltage
• CPC Class Codes: G09G 2320/0295 by monitoring each display pixel
• 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 3/3291 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 pixel including a light-emitting element and a drive element for supplying current flowing in a current path to the light-emitting element is applied with a detection voltage based on a predetermined unit voltage. Based on a value of current flowing in the current path of the drive element, a specific value corresponding to an element characteristic of the drive element is detected. A gradation voltage corresponding to a luminance gradation of display data is generated. Based on the specific value and the unit voltage, a compensated voltage is generated. By compensating the gradation voltage based on the compensated voltage, a compensated gradation voltage is generated. And the compensated gradation voltage is supplied to the display pixel.

Claims

1. A display apparatus for displaying image information in accordance with display data, comprising:

a display panel in which a plurality of display pixels are arranged, each of the display pixels having a light-emitting element and a pixel drive circuit for controlling a light-emitting status of the light-emitting element,

wherein the pixel drive circuit comprises at least;

a first switching element which includes a control terminal and a current path, wherein a first end of the current path is applied with a power source voltage of one of a first power source voltage and a second power source voltage set to different potentials, a second end of the current path is connected to a connection contact point to a first end of the light-emitting element, and the connection contact point is applied with a data voltage based on the display data;

a second switching element which includes a control terminal and a current path, wherein a first end of the current path is applied with the power source voltage and a second end of the current path is connected to the control terminal of the first switching element; and

a voltage holding element connected between the control terminal of the first switching element and the connection contact point, and

wherein;

the first power source voltage has a potential higher than a potential of the data voltage corresponding to the display data and has a voltage value such that a potential difference between the first end of the current path of the first switching element and a second end of the light-emitting element is equal to or lower than a summed voltage as a sum of a voltage for starting light-emitting of the light-emitting element and a threshold voltage of the first switching element,

the second power source voltage has a voltage value for causing the light-emitting element to be in a light-emitting status,

when the data voltage is applied to the second end of the current path of the first switching element, the power source voltage is set to the first power source voltage, and the first end of the current path of the first switching element is connected to the control terminal of the first switching element through the second switching element, and

when a drive current based on a voltage held by the voltage holding element flows in the light-emitting element, the power source voltage is set to the second power source voltage, and the first end of the current path of the first switching element is disconnected from the control terminal of the first switching element.

2. The display apparatus according to claim 1, wherein:

the plurality of display pixels are arranged in a vicinity of respective intersection points of a plurality of selection lines and data lines arranged in a row direction and a column direction in the display panel,

the display apparatus comprises;

a selection driving section which sequentially applies, with a predetermined timing, a selection signal to the respective plurality of selection lines to sequentially set the display pixels in the respective rows to a selected status;

a data driving section which generates a gradation signal in accordance with the display data to supply the gradation signal to the respective display pixels in a row set to the selected status via the respective data lines; and

a power source driving section which supplies the power source voltage, and

the second end of the current path of the first switching element is electrically connected to the data line.

3. The display apparatus according to claim 2, wherein the display pixel further comprises a third switching element which includes a control terminal and a current path, wherein a first end of the current path is connected to the data line and a second end of the current path is connected to the connection contact point.

4. The display apparatus according to claim 1, further comprising a connection status control section which controls a conduction status of the current path of the second switching element,

wherein the connection status control section provides a control by which:

when the first power source voltage is supplied to the first end of the current path of the first switching element to set the light-emitting element to a no-light-emitting status, the current path of the second switching element is conductive so that the first end of the current path of the first switching element is connected to the control terminal of the first switching element, and

when the second power source voltage is supplied to the first end of the current path of the first switching element to set the light-emitting element to a light-emitting status, the current path of the second switching element is not conductive so that the first end of the current path of the first switching element is electrically blocked from the control terminal of the first switching element.

5. A drive method of a display apparatus for displaying image information in accordance with display data, wherein:

the display apparatus includes a display panel in which a plurality of display pixels are arranged, each of the display pixels having a light-emitting element and a pixel drive circuit for controlling a light-emitting status of the light-emitting element,

the pixel drive circuit includes at least;

a first switching element which includes a control terminal and a current path, wherein a first end of the current path is applied with a power source voltage, a second end of the current path is connected to a connection contact point to a first end of the light-emitting element, and the connection contact point is applied with a data voltage based on the display data;

a second switching element which includes a control terminal and a current path, wherein a first end of the current path is applied with the power source voltage and a second end of the current path is connected to the control terminal of the first switching element; and

a voltage holding element connected between the control terminal of the first switching element and the connection contact point, and

the drive method includes;

a writing operation for electrically connecting the control terminal of the first switching element to the first end of the current path of the first switching element through the second switching element, applying the data voltage in accordance with the display data to the second end of the current path of the first switching element, and applying a first power source voltage as the power source voltage to the first end of the current path of the first switching element, wherein the first power source voltage has a potential higher than a potential of the data voltage corresponding to the display data and has a voltage value such that a potential difference between the first end of the current path of the first switching element and the second end of the light-emitting element is equal to or lower than a summed voltage as a sum of a voltage for starting light-emitting of the light-emitting element and a threshold voltage of the first switching element; and

a light-emitting operation for electrically blocking the control terminal of the first switching element from the first end of the current path of the first switching element, and applying a second power source voltage as the power source voltage to the first end of the current path of the first switching element to flow a drive current based on a voltage component held by the voltage holding element in the light-emitting element, wherein the second power source voltage has a voltage value for causing the light-emitting element to be in a light-emitting status and is set to a potential different from the first power source voltage.

6. The drive method according to claim 5, further including a holding operation performed at a timing after the writing operation, for causing the current path of the second switching element to be not conductive to electrically block the control terminal of the first switching element from the first end of the current path of the first switching element and setting the power source voltage to the first power source voltage to allow the voltage holding element to hold a voltage component corresponding to a difference between potentials applied to both ends of the current path of the first switching element.

7. The drive method according to claim 5, wherein the light-emitting operation includes an operation for dividing the plurality of display pixels into a plurality of groups each of which includes a plurality of rows and setting the power source voltage applied to the first end of the current path of the first switching element of each of the display pixels in the plurality of rows of the respective groups as the second power source voltage to simultaneously set light-emitting elements of the display pixels in the plurality of rows of the respective groups to a light-emitting status.

8. The drive method according to claim 5, wherein:

the writing operation includes an operation for causing the current path of the second switching element to be conductive to electrically connect the control terminal of the first switching element to the first end of the current path of the first switching element through the current path of the second switching element, and

the light-emitting operation includes an operation for causing the current path of the second switching element to be not conductive to cause a status between the control terminal of the first switching element and the first end of the current path of the first switching element to be in a nonconductive status.