CN-116343678-B - Electroluminescent display device

Abstract

The application discloses an electroluminescent display device. The electroluminescent display device includes a plurality of pixels. Each of the plurality of pixels includes a driving element including a first gate electrode connected to a first gate node, a second gate electrode facing the first gate electrode, a source electrode connected to a source node, and a drain electrode supplied with a high-level driving voltage, a light emitting device connected between the source node and an input terminal of a low-level driving voltage and configured to emit light in response to a driving current applied from the driving element during a light emission period, and an internal compensation circuit including a first capacitor connected to the first gate node and the source node and configured to sample a threshold voltage of the driving element during a sampling period before the light emission period to reflect the sampled threshold voltage in a gate-source voltage of the driving element. During the sampling period, a sampling boost voltage that increases a sampling current flowing in the driving element is applied to the second gate electrode of the driving element.

Inventors

• XU ZHEN
• ZHENG XUN
• Shen Chexiang

Assignees

• 乐金显示有限公司

Dates

Publication Date

20260512

Application Date

20221017

Priority Date

20211216

Claims (19)

1. 1. An electroluminescent display device comprising: A plurality of pixels, each of the plurality of pixels comprising: A driving element including a first gate electrode connected to a first gate node, a second gate electrode facing the first gate electrode, a source electrode connected to a source node, and a drain electrode supplied with a high-level driving voltage; A light emitting device connected between the source node and an input terminal of a low level driving voltage, the light emitting device configured to emit light in response to a driving current applied from the driving element during a light emitting period, and An internal compensation circuit including a first capacitor connected to the first gate node and the source node, the internal compensation circuit configured to sample a threshold voltage of the driving element during a sampling period prior to the light emission period to reflect the sampled threshold voltage in a gate-source voltage of the driving element, Wherein, during the sampling period, a sampling enhancement voltage that increases a sampling current flowing in the driving element is applied to the second gate electrode of the driving element, and Wherein the internal compensation circuit applies a data voltage to the driving element for a programming period between the sampling period and the light emitting period to program the gate-source voltage of the driving element based on the driving current.
2. 2. The electroluminescent display device according to claim 1 wherein the internal compensation circuit further comprises: A first switching element configured to apply an initial voltage to the first gate node from an initial period before the sampling period until the sampling period in response to a first gate signal; a second switching element configured to apply a reference voltage smaller than the initial voltage to the source node during the initial period in response to a second gate signal, and A third switching element configured to apply the data voltage corresponding to image data to the first gate node during the programming period in response to a third gate signal.
3. 3. The electroluminescent display device according to claim 2, wherein the second gate electrode of the driving element is connected to an external power supply, and the sampling boost voltage is supplied from the external power supply during the sampling period.
4. 4. The electroluminescent display device according to claim 3, wherein the sampling boost voltage has the same voltage level as the initial voltage, and the first and second gate electrodes of the driving element have the same voltage during the sampling period.
5. 5. The electroluminescent display device according to claim 2, wherein the second gate electrode of the driving element is connected to a source electrode of the driving element, and the sampling boost voltage is supplied from the source electrode during the sampling period.
6. 6. The electroluminescent display device according to claim 5 wherein during the sampling period the sampling boost voltage is increased from the reference voltage to a saturation voltage, and the saturation voltage is less than the initial voltage by a threshold voltage of the drive element.
7. 7. The electroluminescent display device according to claim 2, wherein the second gate electrode of the driving element is connected to the first gate electrode of the driving element, and the sampling boost voltage is supplied from the first gate electrode during the sampling period.
8. 8. The electroluminescent display device according to claim 7, wherein the sampling-enhancing voltage is the initial voltage, and during the sampling period, the first gate electrode and the second gate electrode of the driving element have the same voltage as the initial voltage.
9. 9. The electroluminescent display device according to claim 2, wherein the internal compensation circuit further comprises: A second capacitor connected to the source node of the driving element and a second gate node connected to the second gate electrode of the driving element, and A fourth switching element configured to apply the initial voltage to the second gate node from the initial period until the sampling period in response to the first gate signal, Wherein the second gate electrode of the driving element is supplied with the initial voltage as the sampling boost voltage through the fourth switching element during the sampling period.
10. 10. The electroluminescent display device according to claim 9, wherein during the sampling period, the first gate electrode and the second gate electrode of the driving element have the same voltage as the initial voltage.
11. 11. An electroluminescent display device comprising: A plurality of pixels, each of the plurality of pixels comprising: A driving element including a first gate electrode connected to a first gate node, a second gate electrode facing the first gate electrode, a source electrode connected to a source node, and a drain electrode supplied with a high-level driving voltage; A light emitting device connected between the source node and an input terminal of a low level driving voltage, the light emitting device configured to emit light in response to a driving current applied from the driving element during a light emitting period, and An internal compensation circuit including a first capacitor connected to the first gate node and the source node, the internal compensation circuit configured to sample a threshold voltage of the driving element during a sampling period prior to the light emission period to reflect the sampled threshold voltage in a gate-source voltage of the driving element, Wherein a sampling enhancing voltage that increases a sampling current flowing in the driving element is applied to a second gate electrode of the driving element during the sampling period before the light emission period, Wherein, during a programming period between the sampling period and the light emission period, an image quality compensation voltage smaller than the sampling enhancement voltage is applied to a second gate electrode of the driving element, and Wherein the internal compensation circuit applies a data voltage to the driving element during the programming period to program the gate-source voltage of the driving element based on the driving current.
12. 12. The electroluminescent display device according to claim 11, wherein the first and second gate electrodes of the driving element are shorted with each other during the sampling period, and the first and second gate electrodes of the driving element are electrically disconnected from each other from the programming period until the light emission period.
13. 13. The electroluminescent display device according to claim 12, wherein the sampling-enhancing voltage is an initial voltage, and during the sampling period, the first gate electrode and the second gate electrode of the driving element have the same voltage as the initial voltage.
14. 14. The electroluminescent display device according to claim 13, wherein during the programming period, a data voltage greater than the initial voltage is applied to a first gate electrode of the driving element, and an image quality compensation voltage less than the initial voltage is applied to a second gate electrode of the driving element.
15. 15. The electroluminescent display device according to claim 13 wherein the internal compensation circuit comprises: A first switching element configured to apply a reference voltage smaller than the initial voltage to the source node during an initial period before the sampling period in response to a first gate signal; a second switching element configured to apply the initial voltage to the first gate node from the initial period up to the sampling period in response to a second gate signal, and to apply a data voltage greater than the initial voltage to the first gate node during the programming period; A third switching element configured to electrically short-circuit the first gate electrode and the second gate electrode of the driving element from the initial period up to the sampling period and electrically disconnect the first gate electrode of the driving element from the second gate electrode of the driving element from the programming period up to the light emission period in response to a third gate signal; A fourth switching element configured to apply the image quality compensation voltage smaller than the initial voltage to a second gate electrode of the driving element during the programming period in response to a fourth gate signal; A fifth switching element configured to electrically disconnect a drain electrode of the driving element from an input terminal of the high-level driving voltage during the initial period in response to a fifth gate signal and apply the high-level driving voltage to the drain electrode of the driving element from the sampling period up to the light emitting period, and A second capacitor connected to a second gate node connected to the second gate electrode and the source node.
16. 16. An electroluminescent display device comprising: a display panel including a plurality of pixels; a data driver configured to supply data voltages to the plurality of pixels; A gate driver configured to supply gate signals to the plurality of pixels; A timing controller configured to generate a timing control signal for controlling operation timings of the data driver and the gate driver, and A power supply circuit configured to generate voltage signals required for operation of the data driver and the gate driver and for pixel driving, Wherein each of the plurality of pixels includes: A driving element including a first gate electrode connected to a first gate node, a second gate electrode facing the first gate electrode, a source electrode connected to a source node, and a drain electrode supplied with a high-level driving voltage; A light emitting device connected between the source node and an input terminal of a low level driving voltage, the light emitting device configured to emit light in response to a driving current applied from the driving element during a light emitting period, and An internal compensation circuit including a first capacitor connected to the first gate node and the source node, the internal compensation circuit configured to sample a threshold voltage of the driving element during a sampling period prior to the light emission period to reflect the sampled threshold voltage in a gate-source voltage of the driving element, Wherein, during the sampling period, a sampling enhancement voltage that increases a sampling current flowing in the driving element is applied to the second gate electrode of the driving element, and Wherein the internal compensation circuit applies a data voltage to the driving element for a programming period between the sampling period and the light emitting period to program the gate-source voltage of the driving element based on the driving current.
17. 17. A pixel, comprising: A driving element including a first gate electrode connected to a first gate node, a second gate electrode facing the first gate electrode, a source electrode connected to a source node, and a drain electrode supplied with a high-level driving voltage; A light emitting device connected between the source node and an input terminal of a low level driving voltage, the light emitting device configured to emit light in response to a driving current applied from the driving element during a light emitting period, and An internal compensation circuit including a first capacitor connected to the first gate node and the source node, the internal compensation circuit configured to sample a threshold voltage of the driving element during a sampling period prior to the light emission period to reflect the sampled threshold voltage in a gate-source voltage of the driving element, Wherein, during the sampling period, a sampling enhancement voltage that increases a sampling current flowing in the driving element is applied to the second gate electrode of the driving element, and Wherein the internal compensation circuit applies a data voltage to the driving element for a programming period between the sampling period and the light emitting period to program the gate-source voltage of the driving element based on the driving current.
18. 18. An electroluminescent display device comprising: a display panel including a plurality of pixels; a data driver configured to supply data voltages to the plurality of pixels; A gate driver configured to supply gate signals to the plurality of pixels; A timing controller configured to generate a timing control signal for controlling operation timings of the data driver and the gate driver, and A power supply circuit configured to generate voltage signals required for operation of the data driver and the gate driver and for pixel driving, Wherein each of the plurality of pixels includes: A driving element including a first gate electrode connected to a first gate node, a second gate electrode facing the first gate electrode, a source electrode connected to a source node, and a drain electrode supplied with a high-level driving voltage; A light emitting device connected between the source node and an input terminal of a low level driving voltage, the light emitting device configured to emit light in response to a driving current applied from the driving element during a light emitting period, and An internal compensation circuit including a first capacitor connected to the first gate node and the source node, the internal compensation circuit configured to sample a threshold voltage of the driving element during a sampling period prior to the light emission period to reflect the sampled threshold voltage in a gate-source voltage of the driving element, Wherein a sampling enhancing voltage that increases a sampling current flowing in the driving element is applied to a second gate electrode of the driving element during the sampling period before the light emission period, Wherein, during a programming period between the sampling period and the light emission period, an image quality compensation voltage smaller than the sampling enhancement voltage is applied to a second gate electrode of the driving element, and Wherein the internal compensation circuit applies a data voltage to the driving element during the programming period to program the gate-source voltage of the driving element based on the driving current.
19. 19. A pixel, comprising: A driving element including a first gate electrode connected to a first gate node, a second gate electrode facing the first gate electrode, a source electrode connected to a source node, and a drain electrode supplied with a high-level driving voltage; A light emitting device connected between the source node and an input terminal of a low level driving voltage, the light emitting device configured to emit light in response to a driving current applied from the driving element during a light emitting period, and An internal compensation circuit including a first capacitor connected to the first gate node and the source node, the internal compensation circuit configured to sample a threshold voltage of the driving element during a sampling period prior to the light emission period to reflect the sampled threshold voltage in a gate-source voltage of the driving element, Wherein a sampling enhancing voltage that increases a sampling current flowing in the driving element is applied to a second gate electrode of the driving element during the sampling period before the light emission period, Wherein, during a programming period between the sampling period and the light emission period, an image quality compensation voltage smaller than the sampling enhancement voltage is applied to a second gate electrode of the driving element, and Wherein the internal compensation circuit applies a data voltage to the driving element during the programming period to program the gate-source voltage of the driving element based on the driving current.

Description

Electroluminescent display device Cross Reference to Related Applications The present application claims the benefit of korean patent application No. 10-2021-0180763, filed on 12 months 16 of 2021, which is incorporated herein by reference as if fully set forth herein. Technical Field The present disclosure relates to electroluminescent display devices. Background The electroluminescent display device includes a plurality of pixels arranged in a matrix type, and supplies image data synchronized with a scan signal to the pixels, and thus, the pixels realize brightness corresponding to the image data. Each of the plurality of pixels includes a driving element generating a driving current corresponding to image data and a light emitting device emitting light having a luminance proportional to a level of the driving current. The level of the drive current is determined based on the gate-source voltage of the drive element and the threshold voltage of the drive element. However, in the pixel, the threshold voltage of the driving element may be shifted due to pixel process deviation and degradation deviation of the driving element caused by an increase in the use time. The brightness achieved in the pixel is proportional to the level of the drive current. Therefore, when the threshold voltage of the driving element is different between pixels, a luminance deviation may occur in the pixels that have received the same image data. Such a luminance deviation deteriorates display quality. Disclosure of Invention In order to overcome the foregoing problems of the related art, the present disclosure may provide an electroluminescent display device in which a threshold voltage of a driving element is sampled and compensated during operation of a pixel, and thus brightness achieved in the pixel is independent of a variation in the threshold voltage. The present disclosure may provide an electroluminescent display device capable of accurately sampling a threshold voltage of a driving element during operation of a pixel. To achieve these objects and other advantages and in accordance with the purpose of the disclosure, as embodied and broadly described herein, an electroluminescent display device includes a plurality of pixels, each of the plurality of pixels including a driving element including a first gate electrode connected to a first gate node, a second gate electrode facing the first gate electrode, a source electrode connected to a source node, and a drain electrode supplied with a high-level driving voltage, a light emitting device connected between the source node and an input terminal of the low-level driving voltage, the light emitting device configured to emit light in response to a driving current applied from the driving element during a light emission period, and an internal compensation circuit including a first capacitor connected to the first gate node and the source node, the internal compensation circuit configured to sample a threshold voltage of the driving element during a sampling period before the light emission period to reflect the sampled threshold voltage in a gate-source voltage of the driving element, wherein an enhanced voltage that increases a sampling current flowing in the driving element during the sampling period is applied to the second gate electrode of the driving element. In another aspect of the present disclosure, an electroluminescent display device includes a plurality of pixels, wherein each of the plurality of pixels includes a driving element including a first gate electrode connected to a first gate node, a second gate electrode facing the first gate electrode, a source electrode connected to a source node, and a drain electrode supplied with a high-level driving voltage, a light emitting device connected between the source node and an input of the low-level driving voltage, the light emitting device configured to emit light in response to a driving current applied from the driving element during a light emission period, and an internal compensation circuit including a first capacitor connected to the first gate node and the source node, the internal compensation circuit configured to sample a threshold voltage of the driving element during a sampling period before the light emission period to reflect the sampled threshold voltage in the gate-source voltage of the driving element, wherein a sampling enhancement voltage that increases a sampling current flowing in the driving element during the sampling period before the light emission period is applied to the second gate electrode of the driving element, and a quality of an image of the driving element is applied to the second gate electrode during the programming period, the sampling period being smaller than the sampling voltage of the driving electrode. Drawings The accompanying drawings, which are included to provide a further understanding of the disclosure and are incorporated in and constitute a part of this disclosur