Apparatus and method for driving backlight unit

• US 20090021178A1
• Filed: 07/08/2005
• Published: 01/22/2009
• 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: Kikuchi, Kenichi, Ichikawa, Hiroaki, Furukawa, Norimasa
• Granted Patent: US 7,675,249 B2
• Time in Patent Office: Days
• US Class Current: 315/250
• 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 in which the plural LED elements are cascade-connected every three primary colors,

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 of the LED elements on the basis of the signal which has been generated by the signal generating means;

voltage applying means for applying a predetermined voltage every the groups of the LED elements;

light emission quantity detecting means for detecting quantities of ray of light which are emitted from the groups of the LED elements in accordance with the voltage which has been applied by the voltage applying means;

temperature detecting means for detecting temperature or temperatures of the groups of the LED elements; and

control means for controlling the signal generating means on the basis of the light emission quantities which have been detected by the light emission quantity detecting means and the temperature or temperatures which has or have been detected by the temperature detecting means.

2. The drive apparatus as set forth in claim 1,

wherein the signal generating means generates a PWM (Pulse Width Modulation) signal.

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

wherein the light emission detecting means detects quantities of rays of light which have been emitted from the groups of LED elements comprised of the LED elements of arbitrary primary colors.

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

selector means for selecting the group of LED elements constituting the back light unit in accordance with temperature or temperatures which has or have been detected by the temperature detecting means,

wherein the adjustment means serves to adjust light emission quantities of the group of LED elements which have been selected by the selector means on the basis of the signal which has been generated by the signal generating means.

6. The drive apparatus as set forth in claim 1, further including

a memory which stores correction data for correcting, in correspondence with portions where the LED elements are disposed, quantities of rays of light emitted from the LED elements, which have been detected by the light emission quantity detecting means,

wherein the control means controls the signal generating means on the basis of the light emission quantities which have been corrected by the correction data stored in the memory and the temperature or temperatures which has or have been detected by the temperature detecting means.

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

a memory table in which correction value data obtained by a predetermined actual measurement method are stored such that in the case where the light emission detecting means are disposed at a portion apart from the groups of the LED elements, they detect, as weak light, rays of light which are emitted from the groups of the LED elements, while in the case where the light emission detecting means are disposed at a portion near from the groups of the LED elements, they detect, as strong light, rays of light which are emitted from the groups of the LED elements,

wherein the control means corrects light emission quantities which have been detected by the light emission quantity detecting means on the basis of correction value data stored in the memory table to control the signal generating means on the basis of corrected light emission quantities and temperature or temperatures which has or have been detected by the temperature detecting means.

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

adjustment means for suitably adjusting light quantity ratio of the respective LED elements, and a memory table in which temperature information of an arbitrary one color which is caused to be reference in obtaining white light by the adjustment means and correction value data obtained by a predetermined actual measurement method are stored,

wherein the control means corrects light emission quantities which have been detected by the light emission quantity detecting means on the basis of correction value data stored in the memory table to control the signal generating means on the basis of corrected light emission quantities and temperature or temperatures which has or have been detected by the temperature detecting means.

4. The drive apparatus further comprising:

amplitude adjustment means for adjusting amplitude of a constant current value in accordance with temperature or temperatures which has or have been detected by the temperature detecting means,

wherein the voltage applying means serves to allow applied voltage to be variable every the groups of LED elements on the basis of the constant current value which has been delivered from the adjustment means.

9. A drive method for a backlight unit comprised of groups of LED (Light Emitting Diode) elements in which the plural LED elements are cascade-connected every three primary colors,

the drive method comprising:

a voltage application step of applying a predetermined voltage every the groups of the LED elements;

a light emission quantity detection step of detecting quantities of rays of light which are emitted from the groups of the LED elements in accordance with the voltage which has been applied by the voltage application step;

a temperature detection step of detecting temperature or temperatures of the groups of the LED elements;

a signal generation step of generating a signal having an arbitrary amplitude on the basis of light emission quantities which have been detected by the light emission detection step and the temperature or temperatures which has or have been detected by the temperature detection step; and

an adjustment step of adjusting light emission quantities of the groups of the LED elements on the basis of the signal which has been generated by the signal generation step.

10. The drive method as set forth in claim 9,

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

11. The drive method as set forth in claim 9,

wherein the light emission quantity detection step is adapted to detect light quantities which have been emitted from the groups of LED elements comprised of the LED elements having arbitrary primary colors.

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

an amplitude adjustment step of adjusting amplitude of a constant current value in accordance with temperature or temperatures which has or have been detected by the temperature detection step,

wherein the voltage application step is adapted to allow applied voltage to be variable every the groups of LED elements on the basis of a constant current value which has delivered at the adjustment step.

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

a selection step of selecting the group of LED elements constituting the backlight unit in accordance with temperature or temperatures which has or have been detected by the temperature detection step,

wherein the adjustment step is adapted to adjust light emission quantities of the group of LED elements which have been selected by the selection step on the basis of a signal which has been generated by the signal quantity generation step.

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

a correction step of correcting, in correspondence with a portion where the LED elements are disposed, the light emission quantities of the LED elements which have been detected by the light detection step,

wherein the signal generation step is adapted to generate a signal having an arbitrary amplitude on the basis of light emission quantities which have been corrected by the correction step and temperature or temperatures which has or have been detected by the temperature detection step.

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

a correction step of correcting light emission quantities obtained from sensors for detecting quantities of rays of light which are emitted from the groups of LED elements at the light emitting detection step on the basis of correction value data of a memory table in which correction value data obtained by a predetermined actual measurement method are stored such that in the case where the sensors are disposed at a portion apart from the groups of the LED elements, the sensors detect, as weak light, rays of light which are emitted from the groups of the LED elements, while in the case where the sensors are disposed at a portion near from the groups of the LED elements, the sensors detect, as strong light, rays of light which are emitted from the groups of the LED elements,

wherein the signal generation step is adapted to generate a signal having an arbitrary amplitude on the basis of light emission quantities which have been corrected by the correction step and temperature or temperatures which has or have been detected by the temperature detection step.

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

an adjustment step of suitably adjusting light quantity ratio of the LED elements of respective colors; and

a correction step of correcting light emission quantities which have been detected by the light emission quantity detection step on the basis of a correction value of a memory table in which temperature information of arbitrary one color which is caused to be reference in obtaining white light by the adjustment step and correction value data which has been obtained by a predetermined actual measurement method are stored,

wherein the signal generation step is adapted to generate a signal having an arbitrary amplitude on the basis of light emission quantities which have been corrected by the correction step and temperature or temperatures which has or have been detected by the temperature detection step.