Display device and method of driving display device

• US 9,786,220 B2
• Filed: 12/17/2014
• Issued: 10/10/2017
• Est. Priority Date: 06/13/2014
• Status: Active Grant

• Current Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Original Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Inventors: Won, Byeong-Hee, Kim, Il-Nam, Baek, Jong-In, Jo, Min-Gyeong
• Primary Examiner(s): EARLES, BRYAN E
• Application Number:
  US14/574,161
• Publication Number:
  US 20150364091A1
• Time in Patent Office: 1,028 Days
• CPC Class Codes: G09G 2300/0852 being a dynamic memory with more than one capacitor
• CPC Class Codes: G09G 2310/0251 Precharge or discharge of pixel before applying new pixel voltage
• 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 3/3233 with pixel circuitry controlling the current through the light-emitting element

Abstract

A display device and method of driving the display device are disclosed. In one aspect, the display device includes a display panel including a plurality of pixels and a scan driver configured to apply a scan signal having activation and deactivation levels to the pixels. Each of the pixels includes a storage capacitor, a switching transistor, a driving transistor and an emitting element configured to emit light based on an emission current received from the driving transistor. The scan driver is configured to selectively control the activation level of the scan signal so as to control the amount of charge stored in the storage capacitor. The driving transistor is configured to control the emission current based on the amount of charge stored in the storage capacitor.

Claims

1. A display device, comprising:

a display panel including a plurality of pixels;

a scan driver configured to apply a scan signal to the pixels, wherein the scan signal has an activation level and a deactivation level; and

a data driver configured to apply a data signal to the pixels,

wherein each of the pixels comprises;

a storage capacitor configured to store charge based on the data signal;

a switching transistor configured to apply the data signal to the storage capacitor in response to the scan signal;

a driving transistor configured to generate an emission current corresponding to the stored charge; and

an emitting element configured to emit light based on the emission current,

wherein the scan driver is configured to selectively control the activation level of the scan signal,

wherein the scan driver is further configured to select the activation level of the scan signal so as to control the amount of charge stored in the storage capacitor, and

wherein the driving transistor is configured to control the emission current based on the amount of charge stored in the storage capacitor.

2. The display device of claim 1, wherein the scan driver is further configured to decrease the difference between the activation level and the deactivation level of the scan signal and wherein the driving transistor is further configured to increase the emission current based on the decrease in the difference between the activation and deactivation levels of the scan signal.

3. The display device of claim 1, wherein the scan driver is further configured to select the activation level of the scan signal when an operating mode of the display device is changed.

4. The display device of claim 3, wherein the scan driver is further configured to select the activation level of the scan signal when the operating mode of the display device is changed from a normal mode to a photo therapy mode and wherein the emission current is configured to increase based on the selected activation level of the scan signal.

5. The display device of claim 1, wherein the emitting element is an organic light-emitting diode (OLEO).

6. The display device of claim 5, wherein each of the pixels further includes:

an initialization transistor configured to apply an initialization voltage to the storage capacitor in response to an initialization signal;

a first emission control transistor configured to connect a first power supply voltage to a first electrode of the driving transistor in response to an emission signal;

a diode connecting transistor configured to connect a gate electrode of the driving transistor to a second electrode of the driving transistor in response to the scan signal; and

a second emission control transistor configured to connect the second electrode of the driving transistor to the OLED in response to the emission signal.

7. The display device of claim 6, wherein the initialization transistor is further configured to apply the initialization voltage to the storage capacitor so as to initialize the storage capacitor.

8. The display device of claim 7, wherein the storage capacitor is configured to receive the data signal via the switching transistor, the driving transistor and the diode connecting transistor when the scan signal is activated after the storage capacitor is initialized.

9. The display device of claim 8, wherein the storage capacitor is configured to receive the data signal as a data current via the switching transistor, the driving transistor and the diode connecting transistor, wherein the scan driver is further configured to selectively decrease the difference between the activation level and the deactivation level of the scan signal and wherein the data current is configured to decrease based on the decrease in the difference between the activation and deactivation levels of the scan signal.

10. The display device of claim 1, wherein each of the pixels further include:

a boost capacitor connected between a gate electrode of the driving transistor and a gate electrode of the switching transistor, wherein the boost transistor is configured to boost a level of the data signal applied to the storage capacitor when the scan signal is deactivated.

11. The display device of claim 10, wherein the scan driver is further configured to selectively decrease the difference between the activation level and the deactivation level of the scan signal and wherein the level of the data signal boosted by the boost capacitor is configured to decrease based on the decrease in the difference between the activation and deactivation levels of the scan signal.

12. A display device, comprising:

a display panel including a plurality of pixels;

a scan driver configured to apply a scan signal to the pixels, wherein the scan signal has an activation level and a deactivation level; and

a data driver configured to apply a data signal to the pixels,

wherein each of the pixels comprises;

a storage capacitor configured to store charge based on the data signal;

a switching transistor configured to apply the data signal to the storage capacitor in response to the scan signal;

a driving transistor configured to generate an emission current corresponding to the stored charge; and

an emitting element configured to emit light based on the emission current,

wherein the scan driver is configured to selectively control the activation level of the scan signal to control a difference between the activation level and the deactivation level of the scan signal when an operating mode of the display device is changed,

wherein the scan driver is further configured to select the activation level of the scan signal and

wherein the driving transistor is configured to control the emission current based on the selected activation level of the scan signal.

13. The display device of claim 12, wherein the scan driver is further configured to decrease the difference between the activation level and the deactivation level of the scan signal and wherein the driving transistor is further configured to increase the emission current based on the decrease in the difference between the activation and deactivation levels of the scan signal.

14. The display device of claim 12, wherein the scan driver is further configured to selectively control the activation level of the scan signal when the operating mode of the display device is changed from a normal mode to a photo therapy mode and when the operating mode of the display device is changed from the photo therapy mode to the normal mode.

15. The display device of claim 14, wherein when the operating mode of the display device is changed from the normal mode to the photo therapy mode, the driving transistor is further configured to increase the emission current based on the controlled activation level of the scan signal.

16. A method of driving a display device including a plurality of pixels, each of the pixels including a storage capacitor, a switching transistor, a driving transistor and an emitting element, the method comprising:

controlling an activation level of a scan signal applied to the switching transistor,

wherein the scan signal has the activation level and a deactivation level, and

wherein the switching transistor operates as a variable resistor such that the resistance between the source and drain electrodes is based on the level of scan signal;

controlling an amount of charge stored in the storage capacitor based on the activation level of the scan signal;

generating, by the driving transistor, an emission current corresponding to the amount of charge stored in the storage capacitor; and

emitting, by the emitting element, light with a luminance corresponding to the emission current.

17. The method of claim 16, wherein the scan signal has the activation level and a deactivation level, wherein the activation level of the scan signal is controlled by decreasing the difference between the activation level and the deactivation level of the scan signal and wherein driving transistor increases the emission current based on the decrease in the difference between the activation and deactivation levels of the scan signal.

18. The method of claim 16, wherein the activation level of the scan signal is controlled when an operating mode of the display device is changed.

19. The method of claim 18, wherein the activation level of the scan signal is controlled when the operating mode of the display device is changed from a normal mode to a photo therapy mode and wherein the driving transistor increases the emission current based on the controlled activation level of the scan signal.

20. The method of claim 19, wherein the activation level of the scan signal is controlled when the operating mode of the display device is changed from the photo therapy mode to the normal mode and wherein the driving transistor decreases the emission current based on the controlled activation level of the scan signal.