Backlight apparatus, backlight controlling method and liquid crystal display apparatus

• US 20080174544A1
• Filed: 01/23/2008
• Published: 07/24/2008
• Est. Priority Date: 01/24/2007
• Status: Active Grant

• Current Assignee: Thomson Licensing (Vantiva SA)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Morimoto, Tadashi, Ueda, Mitsunori, Mizuta, Minoru
• Granted Patent: US 9,099,045 B2
• Time in Patent Office: Days
• US Class Current: 345/102
• CPC Class Codes: G09G 2310/0232 Special driving of display border areas
• CPC Class Codes: G09G 2310/0237 Switching ON and OFF the backlight within one frame
• CPC Class Codes: G09G 2320/0242 Compensation of deficiencies in the appearance of colours
• CPC Class Codes: G09G 2320/0285 using tables for spatial correction of display data
• 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 2320/0646 Modulation of illumination source brightness and image signal correlated to each other
• CPC Class Codes: G09G 2330/021 Power management, e.g. power saving
• CPC Class Codes: G09G 2360/145 the light originating from the display screen
• CPC Class Codes: G09G 2360/16 Calculation or use of calculated indices related to luminance levels in display data
• CPC Class Codes: G09G 3/3426 the different display panel areas being distributed in two dimensions, e.g. matrix

Abstract

Disclosed herein is a backlight apparatus for controlling a backlight wherein light emitting devices for emitting light of red, green and blue and a switching device for switching on or off light emission of the light emitting devices are provided for each of a plurality of divisional regions formed by division of a lighting region such that the light emission luminance can be varied for each of the regions, the backlight apparatus including: light emission luminance control means; current value storage means; and current control means.

Claims

1. A backlight apparatus for controlling a backlight wherein light emitting devices for emitting light of red, green and blue and a switching device for switching on or off light emission of said light emitting devices are provided for each of a plurality of divisional regions formed by division of a lighting region such that a light emission luminance can be varied for each of the plurality of divisional regions, said backlight apparatus comprising:

light emission luminance control means for varying a pulse width of a pulse signal to be supplied to the switching device in each of the plurality of divisional regions to control the light emission luminance of the divisional region;

current value storage means for storing, for each of the plurality of divisional regions, current values of currents to be supplied to the red, green and blue light emitting devices, the current values being determined such that a whiteness and the light emission luminance of light from the red, green and blue light emitting devices become equal to a predetermined value; and

current control means for controlling the currents to be supplied to the red, green and blue light emitting devices in each of the plurality of divisional regions so that the current values may become equal to the currents stored in said current value storage means.

2. The backlight apparatus according to claim 1, further comprising current value determination means for determining the current values for each of the regions based on the whiteness and the light emission luminance of light from the red, green and blue light emitting devices.

3. A backlight controlling method for performing a backlight controlling process of controlling a backlight wherein light emitting devices for emitting light of red, green and blue and a switching device for switching on or off light emission of said light emitting devices are provided for each of a plurality of divisional regions formed by division of a lighting region such that a light emission luminance can be varied for each of the regions, said backlight controlling method comprising the steps of:

varying a pulse width of a pulse signal to be supplied to the switching device in each of the plurality of divisional regions to control the light emission luminance of the divisional region; and

controlling the currents to be supplied to the red, green and blue light emitting devices in each of the plurality of divisional regions so that the currents may become equal to current values with which a whiteness and the light emission luminance of light from the red, green and blue light emitting devices become equal to a predetermined value.

4. A liquid crystal display apparatus, comprising:

a backlight wherein light emitting devices for emitting light of red, green and blue and a switching device for switching on or off light emission of said light emitting devices are provided for each of a plurality of divisional regions formed by division of a lighting region such that a light emission luminance can be varied for each of the plurality of divisional regions;

light emission luminance control means for varying a pulse width of a pulse signal to be supplied to the switching device in each of the regions to control the light emission luminance of the divisional region;

current value storage means for storing, for each of the plurality of divisional regions, current values of currents to be supplied to the red, green and blue light emitting devices, the current values being determined such that a whiteness and the light emission luminance of light from the red, green and blue light emitting devices become equal to a predetermined value; and

current control means for controlling the currents to be supplied to the red, green and blue light emitting devices in each of the regions so that the currents may become equal to the current values stored in said current value storage means.

5. A backlight apparatus for controlling a backlight wherein light emitting devices for emitting light of red, green and blue and a switching device for switching on or off light emission of said light emitting devices are provided for each of a plurality of divisional regions formed by division of a lighting region such that a light emission luminance can be varied for each of the plurality of divisional regions, said backlight apparatus comprising:

a light emission luminance control section configured to vary a pulse width of a pulse signal to be supplied to the switching device in each of the plurality of divisional regions to control the light emission luminance of the divisional region;

a current value storage section configured to store, for each of the plurality of divisional regions, current values of currents to be supplied to the red, green and blue light emitting devices, the current values being determined such that 1 whiteness and the light emission luminance of light from the red, green and blue light emitting devices become equal to a predetermined value; and

a current control section configured to control the currents to be supplied to the red, green and blue light emitting devices in each of the regions so that the currents may become equal to the current values stored in said current value storage section.