DISPLAY APPARATUS AND LUMINANCE CONTROL METHOD

• US 20100090939A1
• Filed: 11/05/2007
• Published: 04/15/2010
• Est. Priority Date: 11/07/2006
• Status: Active Grant

• Current Assignee: Sharp NEC Display Solutions, Ltd. (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: NEC Display Solutions, Ltd. (NEC Corporation)
• Inventors: Mori, Kengo
• Granted Patent: US 8,587,567 B2
• Time in Patent Office: Days
• US Class Current: 345/99
• CPC Class Codes: G02F 1/133604 with lamps
• CPC Class Codes: G02F 1/133611 including means for improving the brightness uniformity
• CPC Class Codes: G02F 2203/60 Temperature independent
• CPC Class Codes: G09G 3/3406 Control of illumination source illumination devices structurally associated with liquid crystal cells G02F1/1336
• CPC Class Codes: H05B 41/2858 for protecting the lamp against abnormal operating conditions
• CPC Class Codes: Y02B 20/00 Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps

Abstract

A display apparatus according to the present invention using a cold cathode fluorescent lamp as a light source includes: a gradient detector which detects a condition in which one end of the cold cathode fluorescent lamp is disposed higher than an other end thereof; and a controller which conducts control so that emitted luminance of the cold cathode fluorescent lamp is inhibited when the condition in which the one end of the cold cathode fluorescent lamp is disposed higher than the other end thereof is detected by the gradient detector.

Claims

1. A display apparatus using a cold cathode fluorescent lamp as a light source, the apparatus comprising:

a gradient detector which detects a condition in which one end of the cold cathode fluorescent lamp is disposed higher than an other end thereof; and

a controller which conducts control so that emitted luminance of the cold cathode fluorescent lamp is inhibited when the condition in which the one end of the cold cathode fluorescent lamp is disposed higher than the other end thereof is detected by the gradient detector.

7. The display apparatus according to claim 1, further comprising an image display unit which displays a message, wherein the controller causes the image display unit to display a message indicating that control of emitted luminance is performed when control of emitted luminance of the cold cathode fluorescent lamp is conducted.

2. A display apparatus using a cold cathode fluorescent lamp as a light source, the apparatus comprising:

a temperature detector which detects an internal temperature of a housing of the display apparatus;

a time measurement unit which measures elapsed time from initiation of lighting of the cold cathode fluorescent lamp;

a gradient detector which detects a condition in which one end of the cold cathode fluorescent lamp is disposed higher than an other end thereof; and

a controller which projects a saturation temperature of the cold cathode fluorescent lamp based on the elapsed time and an internal temperature difference of the housing between a time of the initiation of lighting of the cold cathode fluorescent lamp and a present time, and which conducts control so that emitted luminance of the cold cathode fluorescent lamp is inhibited in accordance with the saturation temperature, when the condition in which the one end of the cold cathode fluorescent lamp is disposed higher than the other end thereof is detected by the gradient detector.

3. The display apparatus according to claim 2, further comprising an external temperature detector which detects an external temperature of the housing, wherein the controller conducts correction of the projected saturation temperature according to a temperature difference between an external temperature of the housing and an internal temperature of the housing at a present time.

12. The display apparatus according to claim 2, further comprising an image display unit which displays a message, wherein the controller causes the image display unit to display a message indicating that control of emitted luminance is performed when control of emitted luminance of the cold cathode fluorescent lamp is conducted.

13. The display apparatus according to claim 3, further comprising an image display unit which displays a message, wherein the controller causes the image display unit to display a message indicating that control of emitted luminance is performed when control of emitted luminance of the cold cathode fluorescent lamp is conducted.

4. A display apparatus using a cold cathode fluorescent lamp as a light source, the apparatus comprising:

a gradient detector which detects conditions in which one end of the cold cathode fluorescent lamp is disposed higher than an other end thereof;

a temperature detector which detects a temperature of the cold cathode fluorescent lamp; and

a controller which conducts control so that emitted luminance of the cold cathode fluorescent lamp is inhibited according to the temperature detected by the temperature detector, when the condition in which the one end of the cold cathode fluorescent lamp is disposed higher than the other end thereof is detected by the gradient detector.

14. The display apparatus according to claim 4, further comprising an image display unit which displays a message, wherein the controller causes the image display unit to display a message indicating that control of emitted luminance is performed when control of emitted luminance of the cold cathode fluorescent lamp is conducted.

5. A display apparatus using a cold cathode fluorescent lamp as a light source, the apparatus comprising:

a first temperature detector which detects a temperature at one end of the cold cathode fluorescent lamp;

a second temperature detector which detects a temperature at an other end of the cold cathode fluorescent lamp; and

a controller which conducts control so that emitted luminance of the cold cathode fluorescent lamp is inhibited according to a temperature difference between the temperature detected by the first temperature detector and the temperature detected by the second temperature detector.

6. The display apparatus according to claim 5, wherein

a plurality of the cold cathode fluorescent lamps are provided with the first and second temperature detectors, and

the controller controls an emitted luminance of a cold cathode fluorescent lamp having a highest temperature difference among temperature differences between both ends of the respective cold cathode fluorescent lamps, and controls emitted luminance so that luminance control of cold cathode fluorescent lamps other than the one having the highest temperature difference is conformed to the emitted luminance of the cold cathode fluorescent lamp having the highest temperature difference.

15. The display apparatus according to claim 5, further comprising an image display unit which displays a message, wherein the controller causes the image display unit to display a message indicating that control of emitted luminance is performed when control of emitted luminance of the cold cathode fluorescent lamp is conducted.

8. A luminance control method for a display apparatus using a cold cathode fluorescent lamp as a light source, the method comprising:

a gradient detection step of detecting a condition in which one end of the cold cathode fluorescent lamp is disposed higher than an other end thereof; and

a control step of conducting control so that emitted luminance of the cold cathode fluorescent lamp is inhibited when the condition in which one end of the cold cathode fluorescent lamp is disposed higher than the other end thereof is detected by the gradient detection step.

9. A luminance control method for a display apparatus using a cold cathode fluorescent lamp as a light source, the method comprising:

a temperature detection step of detecting an internal temperature of a housing of the display apparatus;

a time measurement step of measuring elapsed time from initiation of lighting of the cold cathode fluorescent lamp;

a gradient detection step of detecting a condition in which one end of the cold cathode fluorescent lamp is disposed higher than an other end thereof; and

a control step of projecting a saturation temperature of the cold cathode fluorescent lamp based on the elapsed time and an internal temperature difference of the housing between a time of the initiation of lightning of the cold cathode fluorescent lamp and a present time, and conducting control so that emitted luminance of the cold cathode fluorescent lamp is inhibited in accordance with the saturation temperature, when the condition in which the one end of the cold cathode fluorescent lamp is disposed higher than the other end thereof is detected by the gradient detection step.

10. A luminance control method for a display apparatus using a cold cathode fluorescent lamp as a light source, the method comprising:

a gradient detection step for detecting a condition in which one end of the cold cathode fluorescent lamp is disposed higher than an other end thereof;

a temperature detection step of detecting a temperature of the cold cathode fluorescent lamp; and

a control step of conducting control so that emitted luminance of the cold cathode fluorescent lamp is inhibited according to the temperature detected by the temperature detection step when the condition in which the one end of the cold cathode fluorescent lamp is disposed higher than the other end thereof is detected by the gradient detection step.

11. A luminance control method for a display apparatus using a cold cathode fluorescent lamp as a light source, the method comprising:

a first temperature detection step of detecting a temperature at one end of the cold cathode fluorescent lamp;

a second temperature detection step of detecting a temperature at an other end of the cold cathode fluorescent lamp; and

a control step of conducting control so that emitted luminance of the cold cathode fluorescent lamp is inhibited according to a temperature difference between the temperature detected by the first temperature detection step and the temperature detected by the second temperature detection step.