Driving device for display and display using the same and driving method of the display

• US 8,692,818 B2
• Filed: 06/18/2009
• Issued: 04/08/2014
• Est. Priority Date: 12/24/2008
• Status: Active Grant

• Current Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Original Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Inventors: Chae, Se-Byung, An, Bo-Young, Lee, Joo-Hyung, Kim, Soon-Dong, Maeng, Ho-Suk, Moon, Seung-Bin
• Primary Examiner(s): Beck, Alexander S
• Assistant Examiner(s): KHAN, IBRAHIM A
• Application Number:
  US12/486,809
• Publication Number:
  US 20100156864A1
• Time in Patent Office: 1,755 Days
• Field of Search: None
• US Class Current: 345/207
• CPC Class Codes: G09G 2320/064 by time modulation of the brightness of the illumination source
• CPC Class Codes: G09G 2360/144 the light being ambient light
• CPC Class Codes: G09G 2360/16 Calculation or use of calculated indices related to luminance levels in display data
• CPC Class Codes: G09G 3/3406 Control of illumination source illumination devices structurally associated with liquid crystal cells G02F1/1336
• CPC Class Codes: G09G 3/3648 using an active matrix G09G3/367 - G09G3/3696 take precedence

Abstract

A driving device for a display and a display using same, and a driving method of the display are provided. The display includes a display panel on which an image is displayed, and at least one optical sensor (photodetector) to detect the intensity of ambient (external) light incident upon the display panel. An external-brightness detector outputs an external-brightness signal based on the intensity of external (ambient) light and a backlight brightness controller changes the brightness of the image displayed (or backlight) on the display panel according to the external-brightness signal. The driving device may be implemented on an integrated circuit adapted to be connected to external-light photodetectors of type 1 or of type 2. The driving device may be may be dynamically configured to generate the external-brightness signal by sensing a voltage level of the light detecting node in a first mode of operation and may be reconfigured to generate the external-brightness signal by sensing a current level of the light detecting node in a second mode.

Claims

1. A display comprising:

a display panel that displays an image;

an external-brightness detector including a light detecting node configured to be connected to a first photodetector configured to detect ambient light while the external-brightness detector operates in a first mode and configured to be connected to a second photodetector configured to detect ambient light while the external-brightness detector operates in a second mode; and

wherein the external-brightness detector outputs a digital external-brightness signal based on sensing the light detecting node and wherein the digital external-brightness signal is based on measuring the analog voltage level of the light detecting node while the external-brightness detector operates in the first mode while connected to the first photodetector and by measuring the analog electric-current level of the light detecting node while the external-brightness detector operates in the second mode while connected to the second photodetector; and

a brightness controller that controls the brightness of the image displayed on the display panel according to the digital external-brightness signal.

2. The display of claim 1,

wherein the external-brightness detector includes a read circuit that samples and measures the light detected by sensing the light detecting node, and an external-brightness signal generator that generates the digital external-brightness signal based on a measurement output from the read circuit.

3. The display of claim 2, wherein the read circuit includes a first measuring circuit and a second measuring circuit, wherein the first measuring circuit is selectively enabled while the external-brightness detector operates in the first mode, and

wherein the second measuring circuit is selectively enabled while the external-brightness detector operates in the second mode;

wherein the first measuring circuit measures the light of the light detecting node by measuring the voltage level of the light detecting node while selectively enabled; and

wherein the second measuring circuit measures the light of the light detecting node by measuring the electric-current level of the light detecting node while selectively enabled.

4. The display of claim 2, wherein the read circuit includes:

a sensing node;

a first switch switchably connecting the light detecting node to the sensing node, a voltage sensor that compares the voltage level of the sensing node with a reference bias level and that outputs the comparison result as the measurement output of the read circuit; and

a current-voltage converter switchably connected between the light detecting node and the sensing node by a second switch, the current-voltage converter varying the voltage level of the sensing node according to the electric-current level of the light detecting node.

5. The display of claim 1, further comprising:

the first photodetector, wherein the first photodetector includes;

a first photodiode that detects external light; and

a first capacitor parallel-connected to the first photo diode;

and further comprising a reference photodetector that includes;

a first reference photodiode that detects reference light; and

a first reference capacitor parallel-connected to the reference photo diode,

wherein while operating in the first mode the external-brightness detector sequentially measures the voltage level of the light detecting node sequentially connected to the first photodiode and to the first reference photo diode.

6. The display of claim 1, wherein the second photodetector includes:

a second photo diode that detects external light; and

a second reference photo diode serially-connected to the second photo diode wherein the second reference photo diode detects reference light,

wherein while operating in the second mode the external-brightness detector measures the electric-current level of the light detecting node connected to the second photo diode and to the reference photodiode.

7. The display of claim 1, wherein the display panel is divided into a display area and a peripheral area, wherein the image is displayed in the display area and not in the peripheral area, and wherein at least one of the first and second photodetectors is formed in the peripheral area of the display panel.

8. The display of claim 1, wherein the brightness controller generates a brightness control signal based on a raw brightness signal and the digital external-brightness signal, and the display further comprises a light-emitting block supplying backlight of the display panel, and a backlight driver controlling the brightness of backlight according to the brightness control signal.

9. The display of claim 8, further comprising:

an image data signal processor that generates a converted image data signal based on a received image data signal; and

a raw brightness signal generator that generates the raw brightness signal based on the received image data signal.

10. The display of claim 1, wherein if the brightness of the external light is high, the brightness controller increases the brightness of backlight, and if the brightness of the external light is low, the brightness controller decreases the brightness of backlight.

11. A driving device of a display comprising:

a brightness controller that controls the brightness of an image displayed on a display panel according to a digital external-brightness signal wherein the external-brightness signal is based upon measuring the analog voltage level of a light detecting node while operating in a first mode, and based upon measuring the analog electric-current level of the light detecting node while operating in a second mode.

12. The driving device of claim 11, further comprising:

an external-brightness detector that outputs the digital external-brightness signal and includes;

a first measuring circuit that outputs a digital measurement based upon measuring the voltage level of the light detecting node while enabled in the first mode;

a second measuring circuit that outputs a digital measurement based upon measuring the electric-current level of the light detecting node while enabled in the second mode; and

an external-brightness signal generator that generates the digital external-brightness signal based on the digital measurement output from the currently enabled one of the first measuring circuit or the second measuring circuit.

13. The driving device of claim 12, wherein the first measuring circuit includes:

a first switch that switchably connects the light detecting node to the sensing input of the first measuring circuit, a voltage sensor that compares a voltage level of the sensing input of the first measuring circuit with a reference bias level and that outputs a comparison result as the digital measurement, and

wherein the second measuring circuit includes the first measuring circuit and;

a current-voltage converter switchably connected between the light detecting node and the sensing input of the first measuring circuit, the current-voltage converter varying the voltage level of the sensing input of the first measuring circuit according to the electric-current level of the light detecting node.

14. The driving device of claim 12, wherein the digital external-brightness signal output by the external-brightness detector is a multi-bit value.

15. The driving device of claim 11, wherein the brightness controller generates the brightness control signal based on received image data and the digital external-brightness signal, and the display further comprises a light-emitting block supplying backlight of the display panel, and a backlight driver controlling the brightness of backlight according to the brightness control signal.

16. The driving device of claim 11, wherein if the brightness of the external light is high, the brightness controller increases the brightness of backlight, and if the brightness of the external light is low, the brightness controller decreases the brightness of backlight.

17. A driving method of a display comprising:

while operating in a first mode, measuring external-light detected by a first photodetector by measuring a voltage level of a light detecting node connected to the first photodetector and outputting a digital external-brightness signal based on the measurement and controlling the brightness of an image displayed on a display panel according to the digital external-brightness signal; and

while operating in a second mode, measuring the external-light detected by a second photodetector by measuring an electric-current level of the light detecting node connected to the second photodetector and outputting the digital external-brightness signal based on the measurement and controlling the brightness of an image displayed on the display panel according to the digital external-brightness signal.

18. The driving method of claim 17, wherein the first photodetector includes:

a first external-light photodiode detecting external light; and

a first capacitor parallel-connected to the first external-light photodiode;

and wherein a first reference photodetector includes;

a first reference photodiode detecting reference light;

a first reference capacitor parallel-connected to the first reference photodiode,

wherein, while operating in the first mode, the outputting of the digital external-brightness signal comprises measuring the voltage level of the light detecting node sequentially connected to the first photodiode and to the first reference photodiode.

19. The driving method of claim 17, wherein the second photodetector includes:

a second photodiode detecting external light and connected to the light detecting node; and

a second reference photo diode, serially-connected to the second photo diode, detecting the reference light and connected to the light detecting node,

wherein, while operating in the second mode, the outputting of the digital external-brightness signal comprises measuring the electric-current level of the light detecting node.

20. The driving method of claim 17, wherein controlling the brightness of the image comprises increasing the brightness of backlight if the brightness of the external light is high, and decreasing the brightness of backlight if the brightness of the external light is low.

21. The driving method of claim 20, wherein the controlling of the brightness of the image comprises generating the brightness control signal based on a received image data signal and the digital external-brightness signal, and controlling the brightness of backlight of the display panel according to the brightness control signal.

22. The driving method of claim 17, wherein the digital external-brightness signal is a multi-bit value.