Power supply unit and display device including the same

• US 10,373,539 B2
• Filed: 08/23/2017
• Issued: 08/06/2019
• Est. Priority Date: 08/31/2016
• Status: Active Grant

• Current Assignee: LG Display Co., Ltd.
• Original Assignee: LG Display Co., Ltd.
• Inventors: Kim, Seunghwan, Kim, Young Sun
• Primary Examiner(s): Edwards, Mark
• Application Number:
  US15/684,467
• Publication Number:
  US 20180061294A1
• Time in Patent Office: 713 Days
• CPC Class Codes: G09G 2310/027 Details of drivers for data electrodes, the drivers handling digital grey scale data, e.g. use of D/A converters
• CPC Class Codes: G09G 2310/0289 Details of voltage level shifters arranged for use in a driving circuit
• CPC Class Codes: G09G 2310/0291 Details of output amplifiers or buffers arranged for use in a driving circuit
• CPC Class Codes: G09G 2310/08 Details of timing specific for flat panels, other than clock recovery
• CPC Class Codes: G09G 2330/026 Arrangements or methods related to booting a display
• 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 3/006 Electronic inspection or testing of displays and display drivers, e.g. of LED or LCD displays testing individual LED's G01R31/2635; testing lamps G01R31/44; testing of optical features of LCD displays G02F1/1309
• CPC Class Codes: G09G 3/3614 Control of polarity reversal in general
• CPC Class Codes: G09G 3/367 with a nonlinear element in series with the liquid crystal cell, e.g. a diode, or M.I.M. element
• CPC Class Codes: G09G 3/3688 suitable for active matrices only
• CPC Class Codes: G09G 3/3696 Generation of voltages supplied to electrode drivers

Abstract

Disclosed are a power supply unit and a display device including the same, which prevent a source drive IC from being damaged by a supply reversal between a VDD voltage and an HVDD voltage. The power supply unit may include a first voltage generator that generates a first voltage and a first voltage line connected to the first voltage generator for supplying the first voltage to a plurality of first source drive ICs of the display panel. A second voltage generator is included that generates a second voltage, and a second voltage line is connected to the second voltage generator for supplying the second voltage to a plurality of second source drive ICs of the display panel. The power supply unit may further include a diode circuit that includes at least one diode connected between the first voltage line and the second voltage line.

Claims

1. A power supply unit for a display device, including:

a first voltage generator for generating a first voltage;

a first voltage line connected to the first voltage generator for supplying the first voltage to a plurality of first source drive ICs of the display panel;

a second voltage generator for generating a second voltage, the second voltage generator being separate from the first voltage generator;

a second voltage line connected to the second voltage generator for supplying the second voltage to a plurality of second source drive ICs of the display panel; and

a diode circuit including a diode, the diode circuit being connected between the first voltage line and the second voltage line and configured to allow a current flow from the first voltage line to the second voltage line if a difference between the first voltage of the first voltage line and the second voltage of the second voltage line is greater than a first predetermined voltage.

2. The power supply unit according to claim 1, further comprising:

a third voltage generator for generating a third voltage that is less than the first voltage; and

a third voltage line connected to the third voltage generator for supplying the third voltage to the first and the second source drive ICs of the display panel.

3. The power supply unit according to claim 2, wherein the third voltage generator is connected to the first voltage line and is configured to generate the third voltage using the first voltage.

4. The power supply unit according to claim 1, wherein the diode circuit includes at least two diodes connected to each other in series.

5. The power supply unit according to claim 4, wherein an anode electrode of a first diode of the at least two diodes connected in series is electrically connected to the first voltage line, and a cathode electrode of a last diode of the at least two diodes connected in series is connected to the second voltage line.

6. The power supply unit according to claim 1, wherein an anode electrode of the diode is electrically connected to the first voltage line and a cathode electrode of the diode is electrically connected to the second voltage line.

7. The power supply unit according to claim 1, further comprising:

a short circuit detector connected to the first voltage line and configured to output a short circuit detection signal indicating whether the first voltage is less than a second predetermined voltage; and

a voltage output controller configured to control the first and second voltage generators based on the short circuit detection signal.

8. The power supply unit according to claim 7, wherein the voltage output controller controls the first and second voltage generators to stop an output of the first and second voltages, respectively, in response to the short circuit signal indicating that the first voltage is less than the second predetermined voltage.

16. The power supply unit according to claim 2, wherein the third voltage generator generates the third voltage based on the first voltage, and the second voltage is supplied to the plurality of second source drive ICs before the third voltage is supplied to the second source drive ICs.

17. The power supply unit according to claim 16, wherein the first voltage is supplied to the plurality of first source drive ICs before the second voltage is supplied to the plurality of second source drive ICs.

9. A display device, including:

a display panel including a plurality of gate lines, a plurality of data lines, and a plurality of pixels formed at respective intersections of the gate lines and the data lines;

a data driver including a plurality of first source drive ICs and a plurality of second source drive ICs, the first and the second source drive ICs being configured to output data voltages to the plurality of data lines; and

a power supply unit, including;

a first voltage generator for generating a first voltage;

a first voltage line connected to the first voltage generator for supplying the first voltage to the plurality of first source drive ICs;

a second voltage generator for generating a second voltage, the second voltage generator being separate from the first voltage generator;

a second voltage line connected to the second voltage generator for supplying the second voltage to the plurality of second source drive ICs; and

at least one diode connected between the first voltage line and the second voltage line, the at least one diode allows a current flow from the first voltage line to the second voltage line if a difference between the first voltage of the first voltage line and the second voltage of the second voltage line is greater than a first predetermined voltage.

10. The display device according to claim 9, wherein the source drive ICs are configured to receive a third voltage and one of the first and the second voltage from the power supply unit.

11. The display device according to claim 10, wherein the source drive ICs include, respectively, an output buffer including at least one positive output buffer for outputting a positive data voltage and at least one negative output buffer for outputting a negative data voltage, wherein one of the first voltage and the second voltage is input to a first reference voltage terminal of the positive output buffer and the third voltage is input to a second reference voltage terminal of the positive output buffer.

12. The display device according to claim 9, wherein the power supply unit includes at least two diodes connected to each other in series between the first voltage line and the second voltage line.

13. The display device according to claim 12, wherein an anode electrode of a first diode of the at least two diodes connected in series is electrically connected to the first voltage line, and a cathode electrode of a last diode of the at least two diodes connected in series is connected to the second voltage line.

14. The display device according to claim 9, wherein the power supply unit further includes:

a short circuit detector connected to the first voltage line and configured to output a short circuit detection signal indicating whether the first voltage is less than a second predetermined voltage; and

a voltage output controller configured to control the first and second voltage generators based on the short circuit detection signal.

15. The display device according to claim 14, wherein the voltage output controller controls the first and second voltage generators to stop an output of the first and second voltages, respectively, in response to the short circuit signal indicating that the first voltage is less than the second predetermined voltage.

18. The display device according to claim 10, further comprising:

a gamma reference voltage supply unit configured to supply first and second gamma reference voltages to at least one of the first source drive ICs or the second source drive ICs,

wherein the at least one of the first source drive ICs or second source drive ICs generates gamma grayscale voltages based on the first and second gamma reference voltages.

19. The display device of claim 18, wherein the at least one of the first source drive ICs or second source drive ICs includes a voltage divider circuit configured to generate the gamma grayscale voltages by voltage dividing the first and second gamma reference voltages.

20. The display device of claim 18, wherein the plurality of first source drive ICs receive the first voltage prior to receiving the third voltage, and the plurality of second source drive ICs receive the second voltage prior to receiving the third voltage.