LIGHT-EMITTING APPARATUS AND DRIVE CONTROL METHOD THEREOF AS WELL AS ELECTRONIC DEVICE

• US 20110074762A1
• Filed: 09/28/2010
• Published: 03/31/2011
• Est. Priority Date: 09/30/2009
• Status: Abandoned Application

• Current Assignee: Casio Computer Company Limited
• Original Assignee: Casio Computer Company Limited
• Inventors: Shimoda, Satoru, SHIRASAKI, Tomoyuki, Kashiyama, Shunji
• Application Number:
  US12/892,172
• Publication Number:
  US 20110074762A1
• Time in Patent Office: Days
• US Class Current: 345/211
• 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 2310/0216 Interleaved control phases for different scan lines in the same sub-field, e.g. initialization, addressing and sustaining in plasma displays that are not simultaneous for all scan lines
• CPC Class Codes: G09G 2320/0233 Improving the luminance or brightness uniformity across the screen
• CPC Class Codes: G09G 2320/0285 using tables for spatial correction of display data
• 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 2320/0295 by monitoring each display pixel
• CPC Class Codes: G09G 2320/045 Compensation of drifts in the characteristics of light emitting or modulating elements
• CPC Class Codes: G09G 2330/02 Details of power systems and of start or stop of display operation
• CPC Class Codes: G09G 2330/12 Test circuits or failure detection circuits included in a display system, as permanent part thereof
• CPC Class Codes: G09G 3/3225 using an active matrix
• 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 light-emitting apparatus includes a light-emitting panel provided with at least one pixel and a data line connected to the pixel, and a drive circuit connected to the light-emitting panel. The pixel includes a light-emitting element, a drive transistor, and a switching element. The drive transistor includes a current path having a first end side connected to the light-emitting element and a second end side to be supplied with a power supply voltage. The switching element is provided between the first end side of the current path and the data line. The drive circuit includes a measurement circuit, which connects the data line and light-emitting element through the switching element after no current is set to run through the current path, to acquire an electric characteristic of the light-emitting element through the data line and first switching element.

Claims

1. A light-emitting apparatus comprising:

a light-emitting panel provided with at least one pixel and a data line connected to the pixel; and

a drive circuit connected to the light-emitting panel,

wherein the pixel includes a light-emitting element, a drive transistor, and a first switching element,

the drive transistor includes a current path having a first end side connected to the light-emitting element and a second end side to be supplied with a power supply voltage,

the first switching element is provided between the first end side of the current path of the drive transistor and the data line, and

the drive circuit includes a measurement circuit to connect the data line and the light-emitting element through the first switching element after no current is set to run through the current path of the drive transistor, acquiring an electric characteristic of the light-emitting element through the data line and the first switching element, the electric characteristic comprising a relation between a voltage applied to the light-emitting element and a current running through the light-emitting element.

2. The light-emitting apparatus according to claim 1, further comprising:

power supply circuit to supply the power supply voltage,

wherein the drive circuit cuts the connection between the power supply circuit and the second end side of the current path of the drive transistor to set no current to run through the current path of the drive transistor.

3. The light-emitting apparatus according to claim 1, wherein the drive circuit sets the power supply voltage to a voltage value at which no current runs through the current path of the drive transistor, and the drive circuit also applies a predetermined off-voltage to turn off the drive transistor to a control terminal of the drive transistor, so that no current runs through the current path of the drive transistor.

4. The light-emitting apparatus according to claim 3, wherein

the pixel includes a second switching element provided between the control terminal of the drive transistor and the data line, and a storage capacitance provided between the control terminal of the drive transistor and the first end side of the current path of the drive transistor, and

the drive circuit brings both ends of the storage capacitance close to the same potential through the data line, the first switching element, and the second switching element to discharge a charge accumulated in the storage capacitance before the application of the off-voltage.

5. The light-emitting apparatus according to claim 1, wherein

the drive circuit includes

a voltage applying circuit, to apply a measurement voltage to the data line,

a current measurement circuit to acquire a value of a current running through the light-emitting element in response to the application of the measurement voltage through the data line and the first switching element.

6. The light-emitting apparatus according to claim 5, wherein the voltage applying circuit applies, as the measurement voltage, a voltage to be a forward bias to the light-emitting element.

7. The light-emitting apparatus according to claim 5, wherein the voltage applying circuit applies, as the measurement voltage, a voltage to be a reverse bias to the light-emitting element.

8. The light-emitting apparatus according to claim 1, wherein the drive circuit includes

a storage circuit to store, as luminance compensation data, at least one of a voltage value and a current value in the electric characteristic of the light-emitting element acquired by the measurement circuit, and

a correction operating circuit to extract a correction amount based on a comparison of the luminance compensation data stored in the storage circuit with a predetermined reference value, correcting externally supplied image data in accordance with the correction amount.

9. The light-emitting apparatus according to claim 1, wherein the light-emitting element comprises an organic electroluminescent element.

10. An electronic device comprising:

an electronic device main unit; and

a light-emitting apparatus to be supplied with image data from the electronic device main unit and driven in accordance with the image data,

the light-emitting apparatus including

a light-emitting panel provided with at least one pixel and a data line connected to the pixel; and

a drive circuit connected to the light-emitting panel,

wherein the pixel includes a light-emitting element, a drive transistor, and a first switching element,

the drive transistor includes a current path having a first end side connected to the light-emitting element and a second end side to be supplied with a power supply voltage,

the first switching element is provided between the first end side of the current path of the drive transistor and the data line, and

the drive circuit includes a measurement circuit to connect the data line and the light-emitting element through the first switching element after no current is set to run through the current path of the drive transistor, acquiring an electric characteristic of the light-emitting element through the data line and the first switching element, the electric characteristic comprising a relation between a voltage applied to the light-emitting element and a current running through the light-emitting element.

11. A drive control, method of a light-emitting apparatus, the method comprising:

a preparation step of preparing the light-emitting apparatus comprising a data line and at least one pixel, the pixel including a light-emitting element, a drive transistor provided with a current path having a first end side connected to the light-emitting element and a second end side to be supplied with a power supply voltage, and a first switching element provided between the first end side of the current path of the drive transistor and the data line;

a cutting step of setting no current to run through the current path of the drive transistor;

a connecting step of connecting the data line and the light-emitting element through the first switching element after the cutting step is executed; and

a characteristic measuring step of acquiring an electric characteristic of the light-emitting element through the data line and the first switching element with the data line and the light-emitting element being connected through the first switching element by the connecting step, the electric characteristic comprising a relation between a voltage applied to the light-emitting element and a current running through the light-emitting element.

12. The drive control method according to claim 11, wherein the cutting step includes a connection cutting step of cutting the connection between the power supply circuit to supply the power supply voltage and the second end side of the current path of the drive transistor, setting no current to run through the current path of the drive transistor.

13. The drive control method according to claim 11, wherein the cutting step includes

a power supply voltage setting step of setting the power supply voltage to a voltage value at which no current runs through the current path of the drive transistor, and

an off-voltage applying step of applying a predetermined off-voltage to turn off the drive transistor to a control terminal of the drive transistor, so that no current runs through the current path of the drive transistor.

15. The drive control method according to claim 11, further comprising:

a compensation data storing step of storing, in a storage circuit as luminance compensation data, at least one of a voltage value and a current value in the electric characteristic of the light-emitting element acquired by the characteristic measuring step;

a correction amount extracting step of extracting correction amount based on a comparison of the luminance compensation data stored in the storage circuit with a predetermined reference value; and

a correcting step of correcting externally supplied image data in accordance with the correction amount.

16. The drive control method according to claim 11, wherein the characteristic measuring step includes

a voltage applying step of applying a measurement voltage to the data line, and

a current measuring step of measuring a value of current running through the light-emitting element in response to the application of the measurement voltage through the data line and the first switching element.

17. The drive control method according to claim 16, wherein the voltage applying step includes applying, as the measurement voltage, a voltage to be a forward bias to the light-emitting element.

18. The drive control method according to claim 16, wherein the voltage applying step includes applying, as the measurement voltage, a voltage to be a reverse bias to the light-emitting element.

19. The drive control method according to claim 18, wherein the characteristic measuring step further includes a pixel defect judging step of judging whether the pixel provided with the light-emitting element is a defective pixel in accordance with the current value measured by the current measuring step when the voltage to be the reverse bias is applied to the light-emitting element as the measurement voltage by the voltage applying step.

14. The drive control method according to claim wherein

the pixel includes a second switching element provided between the control terminal of the drive transistor and the data line, and a storage capacitance provided between the control terminal of the drive transistor and the first end side of the current path of the drive transistor,

the method further comprising an initialization step, executed before the off-voltage applying step, to bring both ends of the storage capacitance close to the same potential through the data line, the first switching element, and the second switching element to discharge a charge accumulated in the storage capacitance.