Display device including photosensors for detecting ambient light and dark current for adjusting a backlight, and display control method thereof

• US 8,330,747 B2
• Filed: 10/27/2008
• Issued: 12/11/2012
• Est. Priority Date: 11/02/2007
• Status: Active Grant

• Current Assignee: Japan Display West Incorporated (Japan Display Incorporated)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Nakanishi, Takayuki, Nakajima, Yoshiharu
• Primary Examiner(s): Nguyen, Chanh
• Assistant Examiner(s): Pham, Long D
• Application Number:
  US12/598,540
• Publication Number:
  US 20100141623A1
• Time in Patent Office: 1,506 Days
• Field of Search: 345/207, 345/102
• US Class Current: 345/207
• CPC Class Codes: G01J 1/32 adapted for automatic variation of the measured or reference value regulation of light intensity G05D25/00
• CPC Class Codes: G01J 1/46 using a capacitor
• CPC Class Codes: G02F 1/13318 Circuits comprising a photodetector
• CPC Class Codes: G02F 1/133601 for spatial active dimming
• CPC Class Codes: G02F 1/133626 providing two modes of illumination, e.g. day-night
• CPC Class Codes: G09G 2310/0237 Switching ON and OFF the backlight within one frame
• CPC Class Codes: G09G 2310/08 Details of timing specific for flat panels, other than clock recovery
• CPC Class Codes: G09G 2320/041 Temperature compensation
• CPC Class Codes: G09G 2320/0626 for control of overall brightness
• CPC Class Codes: G09G 2320/0693 Calibration of display systems
• CPC Class Codes: G09G 2360/144 the light being ambient light
• CPC Class Codes: G09G 2360/145 the light originating from the display screen
• CPC Class Codes: G09G 3/3406 Control of illumination source illumination devices structurally associated with liquid crystal cells G02F1/1336

Abstract

A display device is provided and includes a first photosensor that detects the light amount of ambient light of a display area, a second photosensor that detects dark current arising when light is blocked, and changeover switches that select the first photosensor and the second photosensor. The display device further includes a comparator that compares the output of the selected first photosensor or second photosensor with a predetermined reference value, and control means that calculates the difference between the comparison result by the comparator with the first photosensor and the comparison result by the comparator with the second photosensor and controls the amount of light supplied to the display area corresponding to the calculation result. This configuration suppresses the influence of a detection error due to variation in the performance between the photosensors applied to the display device to thereby accurately adjust the amount of light supplied to the display area.

Claims

1. A display device comprising:

a first detection element that detects a light amount of outside light;

a second detection element that detects a dark current arising when the outside light is blocked;

selection means for selecting either one of the first detection element and the second detection element;

a comparator that compares an output of the first detection element and the second detection element selected by the selection means with a predetermined reference value time divisionally, where a first amount of time is measured from a detection start of the first detection element to a time at which a detection value of the first detection element exceeds the predetermined reference value and said first amount of time is stored as a first comparison result, and a second amount of time is measured from a detection start of the second detection element to a time at which a detection value of the second detection element exceeds the predetermined reference value and said second amount of time is stored as a second comparison result; and

control means for calculating a difference between the first comparison result obtained by the comparator when the first detection element is selected by the selection means and the second comparison result obtained by the comparator when the second detection element is selected, and controlling an amount of light supplied to the display area depending on a calculation result.

2. The display device according to claim 1, further comprising

reference value switch means for switching the predetermined reference value input to the comparator between the cases when the first detection element is selected by the selection means and when the second detection element is selected.

3. The display device according to claim 1, further comprising

additional capacitance switch means for switching additional capacitance connected in common to the first and second detection elements between the cases when the first detection element is selected by the selection means and when the second detection element is selected.

4. A display control method of a display device including a first detection element that detects a light amount of outside light and a second detection element that detects a dark current arising when the outside light is blocked, the method comprising:

a step of detecting a current dependent on an ambient light amount by the first detection element and calculating a first comparison result obtained when the outside light is received through comparison with a predetermined reference value, where a first amount of time is measured from a detection start of the first detection element to a time at which a detection value of the first detection element exceeds the predetermined reference value and said first amount of time is stored as the first comparison result;

a step of detecting the dark current arising when the outside light is blocked by the second detection element and calculating a second comparison result obtained when the outside light is blocked through comparison with a predetermined reference value, where a second amount of time is measured from a detection start of the second detection element to a time at which a detection value of the second detection element exceeds the predetermined reference value and said second amount of time is stored as the second comparison result; and

a step of calculating a difference between the first comparison result obtained when the outside light is received and the second comparison result obtained when the outside light is blocked, and controlling an amount of light supplied to the display area depending on a calculation result.

5. The display control method according to claim 4, wherein

a predetermined reference value applied to a calculation of the respective second and first comparison results is switched between the cases when current is detected by the second detection element and when current is detected by the first detection element.

6. The display control method according to claim 4, wherein

additional capacitance connected in common to the first and second detection elements is switched between the cases when current is detected by the second detection element and when current is detected by the first detection element.

7. The display control method according to claim 6, wherein

the additional capacitance is set depending on an ambient temperature of the display area.

8. An electronic apparatus comprising a display device provided in a case, the display device including:

a first detection element that detects a light amount of outside light;

a second detection element that detects a dark current arising when the outside light is blocked;

selection means for selecting either one of the first detection element and the second detection element;

a comparator that compares an output of the first detection element and the second detection element selected by the selection means with a predetermined reference value time divisionally, where a first amount of time is measured from a detection start of the first detection element to a time at which a detection value of the first detection element exceeds the predetermined reference value and said first amount of time is stored as a first comparison result, and a second amount of time is measured from a detection start of the second detection element to a time at which a detection value of the second detection element exceeds the predetermined reference value and said second amount of time is stored as a second comparison result; and

control means for calculating a difference between the first comparison result obtained by the comparator when the first detection element is selected by the selection means and the second comparison result obtained by the comparator when the second detection element is selected, and controlling an amount of light supplied to the display area depending on a calculation result.