Apparatus and method for driving backlight unit

• US 8,111,020 B2
• Filed: 01/22/2010
• Issued: 02/07/2012
• Est. Priority Date: 07/12/2004
• Status: Active Grant

• Current Assignee: Saturn Licensing LLC (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Furukawa, Norimasa, Ichikawa, Hiroaki, Kikuchi, Kenichi
• Primary Examiner(s): Le, Tung X
• Application Number:
  US12/656,268
• Publication Number:
  US 20100181921A1
• Time in Patent Office: 746 Days
• Field of Search: 315/149, 315152-153, 315155-158, 315/246, 315/250, 315/291, 315307-309, 315/312, 345/72, 345 82- 85, 345 88- 89, 345/102, 345/204, 345/690
• US Class Current: 315/309
• CPC Class Codes: G09G 2320/041 Temperature compensation
• CPC Class Codes: G09G 2320/0633 by amplitude modulation of the brightness of the illumination source
• CPC Class Codes: G09G 2320/064 by time modulation of the brightness of the illumination source
• CPC Class Codes: G09G 2360/145 the light originating from the display screen
• CPC Class Codes: G09G 3/3413 Details of control of colour illumination sources
• CPC Class Codes: G09G 3/342 using several illumination sources separately controlled corresponding to different display panel areas, e.g. along one dimension such as lines
• CPC Class Codes: H05B 45/28 using temperature feedback
• CPC Class Codes: H05B 45/3725 Switched mode power supply [SMPS]

Abstract

The present invention is directed to a drive apparatus for a backlight unit (20) in which plural LED (Light Emitting Diode) elements are cascade-connected every three primary colors, which comprises a signal generating unit (44) for generating a signal having an arbitrary amplitude, an adjustment unit (50) for adjusting light emission quantities of groups of LED elements (30) on the basis of the signal which has been generated by the signal generating unit (44), a voltage applying unit (41) for applying a predetermined voltage every the groups of LED elements (30), light emission quantity detecting units (33) for detecting quantities of rays of light which have been emitted from the groups of LED elements (30), calorific value detecting units (32) for detecting calorific values emitted from the groups of LED elements in accordance with the voltage which has been applied to the voltage applying unit (41), and a control unit (50) for controlling the signal generating unit (44) on the basis of light emission quantities which have been detected by the light emission quantity detecting units (33) and calorific values which have been detected by the calorific value detecting units (32).

Claims

1. A drive apparatus for a backlight unit comprised of groups of LED (Light Emitting Diode) elements, each of the groups including a plurality of LED elements, the drive apparatus comprising:

signal generating means for generating a signal having an arbitrary amplitude;

adjustment means for adjusting light emission quantities of the groups based on the generated signal;

voltage applying means for applying a predetermined voltage to the groups;

light emission quantity detecting means for detecting quantities of light emitted from the groups;

temperature detecting means for detecting temperatures of the groups;

control means for controlling the signal generating means based on the detected light emission quantities and the detected temperatures; and

selector means for selecting at least one of the groups based on the detected temperatures,

wherein the adjustment means adjusts the light emission quantities of the selected at least one of the groups based on the generated signal.

2. The drive apparatus as set forth in claim 1, wherein the generated signal is a PWM (Pulse Width Modulation) signal.

3. The drive apparatus as set forth in claim 1, further comprising:

amplitude adjustment means for adjusting the amplitude of a constant current value based on the detected temperatures, and delivering the constant current value to the voltage applying means,

wherein the voltage applying means varies the voltage applied to the groups based on the constant current value.

4. The drive apparatus as set forth in claim 1, further comprising:

a memory that stores correction data for correcting the detected light emission quantities based on where the LED elements are disposed,

wherein the control means corrects the detected light emission quantities based on the correction data, and controls the signal generating means based on the corrected detected light emission quantities and the detected temperatures.

5. The drive apparatus as set forth in claim 1, further comprising:

a memory table that stores correction value data for correcting the light emission quantities based on where the groups are disposed relative to the light emission detecting means, the light emitted from groups further from the light emission detecting means being designated as weaker light, and the light emitted from groups nearer to the light emission detecting means being designated as stronger light,

wherein the control means corrects the detected light emission quantities based on the correction value data, and controls the signal generating means based on the corrected detected light emission quantities and the detected temperatures.

6. A drive method for a backlight unit comprised of groups of LED (Light Emitting Diode) elements, each of the groups including a plurality of LED elements, the drive method comprising:

a voltage application step of applying a predetermined voltage to the groups;

a light emission quantity detection step of detecting quantities of light emitted from the groups;

a temperature detection step of detecting temperatures of the groups;

a signal generation step of generating a signal having an arbitrary amplitude based on the detected light emission quantities and the detected temperatures;

an adjustment step of adjusting light emission quantities of the groups based on the generated signal; and

a selection step of selecting at least one of the groups based on the detected temperatures,

wherein the adjustment step is adapted to adjust the light emission quantities of the selected at least one of the groups based on the generated signal.

7. The drive method as set forth in claim 6,

wherein the signal generation step is adapted to generate the generated signal as a PWM (Pulse Width Modulation) signal.

8. The drive method as set forth in claim 6, further comprising:

an amplitude adjustment step of adjusting the amplitude of a constant current value based on the detected temperatures,

wherein the voltage application step is adapted to vary the voltage applied to the groups based on the constant current value.

9. The drive method as set forth in claim 6, further comprising:

a correction step of correcting the detected light emission quantities based on where the LED are disposed,

wherein the signal generation step is adapted to generate the generated signal based on the corrected detected light emission quantities and the detected temperatures.

10. The drive method as set forth in claim 6, wherein the light emission quantity detection step includes detecting, with sensors, the quantities of light emitted from the groups, and the drive method further comprises:

a correction step of correcting the detected light emission quantities based on correction value data stored in a memory table, the correction value data corresponding to the relative positions of the sensors and the groups, the light emitted from groups further from the sensors being designated as weaker light, and the light emitted from groups nearer to the sensors being designated as stronger light,

wherein the signal generation step is adapted to generate the generated signal based on the corrected detected light emission quantities and the detected temperatures.