Window brightness enhancement for lc display

• US 20050219197A1
• Filed: 03/11/2003
• Published: 10/06/2005
• Est. Priority Date: 04/02/2002
• Status: Active Grant

• Current Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Casale, Carlo, Pasqualini, Giuseppe
• Granted Patent: US 7,164,409 B2
• Time in Patent Office: Days
• US Class Current: 345/102
• CPC Class Codes: G09G 2320/0606 Manual adjustment
• CPC Class Codes: G09G 2320/0626 for control of overall brightness
• 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 2320/0653 Controlling or limiting the speed of brightness adjustment of the illumination source
• CPC Class Codes: G09G 2320/0686 with two or more screen areas displaying information with different brightness or colours
• 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
• CPC Class Codes: G09G 3/36 using liquid crystals
• CPC Class Codes: G09G 5/10 Intensity circuits
• CPC Class Codes: G09G 5/14 Display of multiple viewports

Abstract

In a LCD monitor, a predetermined part (PA) of the displayed information is highlighted by causing the backlighting to produce more light. The area outside the predetermined area (PA) is kept at a substantially constant brightness by adjusting the video data driving the panel. The actual amount of light produced by the backlighting is measured to obtain a more constant brightness outside the predetermined area (PA).

Claims

1. A display apparatus (DAP) comprising:

a liquid crystal display (LCD) for receiving an input display signal (DS) to display an adapted display signal (DSA) being enhanced within a predetermined area (PA) of a display screen (SCR) of the liquid crystal display (LCD) in response to an enhancement control signal (ECS),

a lamp driver circuit (LDC) for changing a property of the light emitted by a backlighting lamp (BLL) illuminating the liquid crystal display (LCD), under control of a light control signal (LCS),

a data controller (DCO) for adapting the display signal (DS) under control of a data control signal (DCS) to obtain a substantially unchanged display on the display screen (SCR) outside the predetermined area (PA),

a light sensor (LS) for measuring the property of the light to obtain a measured property of the light (ML), and

an enhancement controller (EC) comprising a first input for receiving the enhancement control signal (ECS) and a second input coupled to the light sensor (LS), for adapting the data control signal (DCS) and the light control signal (LCS), both in response to the enhancement control signal (ECS), and for determining the data control signal (DCS) and/or the light control signal (LCS) in correspondence with the measured property of the light (MPL).

2. A display apparatus as claimed in claim 1, characterized in that the enhancement controller (EC) further comprises:

a memory (MEM) for storing the measured property of the light during a period in time that the enhancement control signal (ECS) indicates that no enhancement is present, and

a calculating circuit (CAL) for calculating a value of the data control signal (DCS) based on the stored measured property (SMPL) and a measured property (MPL) of the light after an instant the enhancement control signal (ECS) indicates that the enhancement is present.

3. A display apparatus as claimed in claim 1, characterized in that the property of the light is the brightness, and in that the lamp driver circuit (LDC) comprises:

a pulse width modulator (PWM) for generating a pulse width control signal (PWC) having a duty cycle dependent on a brightness control signal (BCS),

a series arrangement of a current driver (CUD), a switching device (CSW), and the backlighting lamp (BLL), the current driver (CUD) has an input for receiving a current control signal (ES) and an output for supplying a predetermined current (IL) to the backlighting lamp (BLL) when the switching device (CSW) is closed, the switching device (CSW) has a control input for receiving the pulse width control signal (PWC) to determine on and off times of the switching device (CSW), and

the enhancement controller (EC) further comprises;

a control signal generator (CSG) for generating the light control signal (LCS) comprising the brightness control signal (BCS) and the current control signal (CCS) based on the enhancement control signal (ECS), and wherein during a transition of the brightness, the brightness control signal (BCS) is adapted to change the duty cycle, and if the transition is not proceeding fast enough, the current control signal (CCS) is adapted to temporary change the current (IL) through the backlighting lamp (BLL).

4. A system comprising a display apparatus (DAP), and a computer (COM) for generating a display signal (DS) and an enhancement control signal (ECS) indicating a required enhancement of the display signal (DS) within a predetermined area (PA) on a display screen (SCR) of the display apparatus (DAP),

the display apparatus (DAP) comprising:

a liquid crystal display (LCD) for receiving an input display signal (DS) to display an adapted display signal (DSA) being enhanced within a predetermined area (PA) of the display screen (SCR) of the liquid crystal display (LCD) in response to an enhancement control signal (ECS),

a lamp driver circuit (LDC) for changing a property of the light emitted by a backlighting lamp (BLL) illuminating the liquid crystal display (LCD), under control of a light control signal (LCS),

a data controller (DCO) for adapting the display signal (DS) under control of a data control signal (DCS) to obtain a substantially unchanged display on the display screen (SCR) outside the predetermined area (PA),

a light sensor (LS) for measuring the property of the light to obtain a measured property of the light, and

an enhancement controller (EC) comprising a first input for receiving the enhancement control signal (ECS) and a second input coupled to the light sensor (LS), for adapting the data control signal (DCS) and the light control signal (LCS), both in response to the enhancement control signal (ECS), and for determining the data control signal (DCS) and/or the light control signal (LCS) in correspondence with the measured property of the light (MEL).

5. A method of enhancing a predetermined area (PA) of a display screen (SCR) of a liquid crystal display (LCD) in response to an enhancement control signal (ECS), the method comprising:

changing (LDC) a property of light emitted by a backlighting lamp (BLL) illuminating the liquid crystal display (LCD), under control of a light control signal (LCS),

adapting (DCO) a display signal (DS) under control of a data control signal (DCS) to obtain a substantially unchanged display on the display screen (SCR) outside the predetermined area (PA),

measuring (LS) the property of the light, and

receiving (EC) the enhancement control signal (ECS) and the measured property of the light (MPL) for adapting (EC) the data control signal (DCS) and the light control signal (LCS), both in response to the enhancement control signal (ECS), and for determining (EC) the data control signal (DCS) and/or the light control signal (LCS) in correspondence with the measured property of the light (MPL).