JPH10207400A - Liquid crystal display device and its light source control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to view only required information in the state reducing power consumption by making a backlight of an equipment partially lightable and turning only a beforehand specified area and the vicinity of a change part of a display on. SOLUTION: Turn-on places are selected from input coordinates for turning the backlights 1a-1n in the vicinity of a pen inputted position. Then, a display of a liquid crystal element is started by writing the data to be displayed in a VRAM, or sending the data held in the VRAM to a display device. Then, only the selected backlights are set in a controller 4, and currents by the number of pieces are set in an inverter 5 to be turned on. After a fixed time, a pen input state is confirmed, and when the pen is upped, and the input is ended, all backlights 1a-1n are turned off after waiting for a prescribed time. In such a manner, the backlights 1a-1n are made partially lightable, and only the vicinity of the pen inputted positions are turned on.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a liquid crystal display device used for a personal computer or the like and a light source control method thereof.

[0002]

2. Description of the Related Art Recently, liquid crystal display devices are mainly used as display means for personal computers such as laptops, notebooks, and sub-notes. This liquid crystal display device is a reflective black and white, transmissive (with backlight)
There are types such as black and white and transmission color. In the case of color display, it is necessary to use a backlight (light source) from the viewpoint of color reproducibility. As a backlight, an EL (electroluminescence) element or a backlight using a cold cathode tube is mainly used. The EL element has a planar shape, and when a driving voltage is applied, the entire plane is excited to emit light. On the other hand, one or more cold cathode tubes are arranged and used on the back and side surfaces of the liquid crystal element.

One of the functions of portable information devices such as notebook personal computers is battery life. For this reason, many devices use power management function programs to reduce power consumption. The backlight is normally turned on when the power is turned on, and is turned off when the power is turned off. It is controlled to turn on the backlight. This power management can perform the same setting not only for the backlight but also for all devices in the device.

[0004]

However, in the current backlight control, the display output of the graphics controller is stopped at the same time as erasing the entire display screen, so that all display data cannot be read. . Also,
Even though the entire light amount can be reduced, it cannot be partially reduced, so that it cannot be used while suppressing power consumption.

SUMMARY OF THE INVENTION An object of the present invention is to provide a liquid crystal display device capable of displaying only necessary information while turning off a backlight in an unnecessary area to suppress overall power consumption and extending battery life, and a light source control method therefor. Is to provide.

[0006]

A first aspect of the present invention is a transmissive liquid crystal display device, which comprises a liquid crystal element, a plurality of light sources located on the back of the liquid crystal element, and a specific position detecting means on a screen. Means for partially activating only the light source corresponding to the position specified by the detection means, and means for adjusting the light amount of the light source according to the width of the activated portion. A second aspect of the present invention is the light source control method for a transmission type liquid crystal display device having a plurality of light sources on the back surface of a liquid crystal element, wherein a specific position on a screen is determined, and the position corresponding to the specific position is determined. It is characterized in that only the light source is partially activated, and the light amount of the light source is adjusted according to the width of the activated portion.

[0007]

FIG. 1 shows a partial configuration of an embodiment of the liquid crystal display device of the present invention. This figure is a block diagram of a portion related to the light source control method of the present invention.

In FIG. 1, cold cathode tubes 1a to 1n constitute a backlight. These cold cathode tubes 1a to 1
n is on / off controlled by a plurality of switch groups 2. Which cold-cathode tube is turned on / off and how much current is supplied to the cold-cathode tube are written in a setting register 3 in accordance with an instruction of a CPU described later. According to this value,
The switch group 2 is controlled, and a drive current is instructed in an analog or digital manner to the inverter 5 that drives the cold cathode tubes 1a to 1n. The cold cathode fluorescent lamp needs the inverter 5 to be driven at about 100 V and 50 kHz. Since the amount of light emitted from the cold-cathode tube is proportional to the current, if the number of lighting tubes changes, the current to be set is changed accordingly. Since it is also used for adjusting the amount of light during full lighting, when the number of lighting is reduced, it is proportionally calculated from the current at full lighting.

FIG. 2 illustrates a partial lighting state of the backlight according to the present embodiment. In the figure, 22 is a cold cathode tube, 21
Is an input pen, FIG. 2 (a) is a backlight when all lights are on,
(B) shows that when a pen input is detected in the sleep (power saving) mode, the cold cathode tubes only near the pen input are turned on. FIG. 3 shows a screen in the state of FIG. 2B, in which 31 is a lighted portion and 32 is a non-lighted portion. As shown in FIG. 3, the display in the vicinity of the pen can be visualized and viewed, and other parts cannot see the information due to the non-lighting of the backlight.

FIG. 4 is an overall configuration diagram of an information device provided with the liquid crystal display device of the present embodiment. As this information device, for example, a notebook or laptop personal computer can be mentioned.

In FIG. 1, reference numeral 6 denotes a CPU, which is an element for interpreting and executing instructions. 7 is a memory controller or PC
An element for bridging with the I bus, 8 is a main memory composed of a DRAM or the like, 9 is a graphics controller for controlling a display screen, 10 is a memory for storing element data, and 11 is a display. Liquid crystal element.

Reference numeral 12 denotes a bridge for converting PCI to a conventional ISA bus. Reference numeral 13 denotes a chipset element including serial communication, parallel communication, floppy, I / O, and the like. Reference numeral 14 denotes an integrated liquid crystal element. Digitizers that can take input coordinates with a pen include a resistive type, an ultrasonic type, and an electromagnetic induction type. Reference numeral 15 denotes a conventional keyboard and mouse input unit, and reference numeral 16 denotes a SCSI controller, which controls devices such as a hard disk 17.
Reference numeral 18 denotes a communication unit for connecting to a LAN or a telephone line, and 19 denotes an interface with a PCMCIA card.

FIG. 5 shows a flowchart of the backlight control in this embodiment. First, the device enters a sleep mode by a method not shown. In this mode, the digitizer checks at every predetermined time whether there is a pen input (51). Because of the sleep mode, the interval for checking the pen input is longer than in the normal mode.
If there is a pen input, the process proceeds to the next step (52) to calculate the coordinates of the pen. Then, in order to turn on the backlight near the position where the pen is input, a lighting place is selected from the input coordinates (53). Next, the data to be displayed is written to the VRAM, or the data held in the VRAM is sent to the display to start the display of the liquid crystal element (54). Only the selected backlight is set in the controller (4 in FIG. 1), and the inverter (5 in FIG. 1) is turned on by setting a current corresponding to the number of the inverters (55). After a certain period of time (56), the state of the pen input is checked (57). If the pen is still in the input state, the location to be lit from the input position is recalculated (5).
8) If the lighting position changes, go back and start lighting again. if,
If the pen is up and input has been completed, a predetermined time (for example, 5 seconds) is waited (59), all backlights are turned off (60), and the process returns to the initial sleep mode again. Of course, it is possible to use the conventional function by pen input even at the time of this partial lighting, and only the visible range is narrow. Further, in the present embodiment, the input by means of the pen is described as the input means, but a backlight near the pointing position of the mouse or the cursor position of the keyboard may be turned on.

As described above, the backlight can be partially turned on, and only the vicinity of the position where the pen is input is turned on, so that only necessary information can be viewed with reduced power consumption.

FIG. 6 shows a second embodiment of the present invention. This embodiment is an example in which a window on a screen is specified as a specific position at which the backlight is partially turned on. In the figure, 61 to 63 are windows. FIG. 6 shows a state in which the backlight of only the top (active) window on the multi-window screen is turned on. However, in this figure, the backlight and the window completely match, but in practice there is some deviation.

FIG. 7 shows a flowchart of the backlight control in this embodiment. The chart shown in FIG. 7 is a chart at the time of setting to enter this mode. First, the active window is checked (71), and the location of the backlight to be turned on is calculated from the position and size of the window (72). Is turned on, and unnecessary ones are turned off (73) to enter the sleep mode.

FIG. 8 shows a flowchart of the backlight control according to the third embodiment. The present embodiment is an example in which the backlight is lit as a specific position at a part that constantly changes on the screen, such as a clock, and an example in which attention is paid to a blinking part of the clock and only the vicinity thereof is lit. is there.

In the present embodiment, at the time of setting to enter the sleep mode, a portion having movement on the current screen is searched (8).
1) If there is a corresponding portion, the effective range of the portion is specified (82), the place to be turned on is calculated (83), the designated backlight is turned on, and the sleep mode is entered (8).
4). If there is no moving part, the display mode is turned off (85), the backlight is turned off (86), and the normal sleep mode (full backlight off) is entered.

FIG. 9 shows a flowchart of the backlight control according to the fourth embodiment. This embodiment is an example of a case where it is desired to display a message by some trigger during the sleep mode. Specifically, the vicinity of a window to be newly displayed due to an incoming mail from the outside is turned on. Things. Other than this, an alarm function or some warning message built into the scheduler or the like is also conceivable.

In this embodiment, it is detected whether or not the above message is displayed (91).
When a message is issued, the backlight lighting location is calculated from that location (92), and the actual message is displayed (93), and the backlight is turned on (94).

FIG. 10 shows a flowchart of the backlight control according to the fifth embodiment. In the present embodiment, a lighting place is set in advance by using an area designating means such as a pen or a mouse. By setting a specific area (10
1) The backlight to be turned on is calculated (102) and turned on (103).

In each of the above embodiments, a plurality of cold cathode tubes are used as a backlight.
EL elements 11 arranged in a matrix as shown in FIG.
One is fine. Alternatively, partial light supply may be performed between a conventional cold-cathode tube (two side surfaces + diffusion plate) and a liquid crystal element by using a planar matrix light shutter (for example, an electrochromic element).

[0023]

As described above, according to the present invention,
As one of the power-saving modes, the backlight of the device can be partially turned on, and only the necessary information is reduced by turning on only the area specified by the user or in the vicinity of the change in display, reducing power consumption. It became possible to see in.

[Brief description of the drawings]

FIG. 1 is a block diagram of a portion related to a light source control method of a liquid crystal display device of the present invention.

FIG. 2 is a diagram showing a partial lighting state of a backlight according to the first embodiment of the present invention.

FIG. 3 is a diagram showing a partially lit backlight shown in FIG. 2;

FIG. 4 is an overall block diagram of the liquid crystal display device according to the first embodiment of the present invention.

FIG. 5 is a flowchart of backlight control according to the first embodiment of the present invention.

FIG. 6 is a diagram showing a multi-window screen in which a backlight is partially turned on in a second embodiment of the present invention.

FIG. 7 is a flowchart of backlight control according to the second embodiment of the present invention.

FIG. 8 is a flowchart of backlight control according to a third embodiment of the present invention.

FIG. 9 is a flowchart of backlight control according to a fourth embodiment of the present invention.

FIG. 10 is a flowchart of backlight control according to a fifth embodiment of the present invention.

FIG. 11 is a diagram showing an EL element that can be used as a light source of the liquid crystal display device of the present invention.

[Explanation of symbols]

 1a to 1n cold cathode tube (backlight) 2 switch group 3 setting register 4 controller 5 inverter 6 CPU 7 PCI bridge 8 main memory 9 graphics controller 10 VRAM 11 liquid crystal element 12 ISA bridge 13 peripheral chipset 14 digitizer 15 keyboard and mouse Reference Signs List 16 SCSI controller 17 Hard disk 18 Communication means 19 PCMCIA card interface 21 Input pen 22 Backlight 31 Lighting part 32 Non-lighting part 61-63 Window 111 EL element

Claims (8)

[Claims] 1. A transmissive liquid crystal display device, comprising: a liquid crystal element, a plurality of light sources located on the back of the liquid crystal element, a specific position detecting means on a screen, and a position specified by the detecting means. A liquid crystal display device comprising: means for partially activating only the corresponding light source; and means for adjusting the light amount of the light source according to the width of the activated part. 2. The liquid crystal display device according to claim 1, wherein said specific position detecting means detects a position designated by an input means on a screen. 3. The liquid crystal display device according to claim 1, wherein said specific position detecting means detects a change portion of display information on a screen. 4. The liquid crystal display device according to claim 1, wherein said specific position detecting means detects a window displayed on a screen. 5. A light source control method for a transmission type liquid crystal display device having a plurality of light sources on the back of a liquid crystal element, wherein a specific position on a screen is determined, and only a light source corresponding to the specific position is determined. A light source control method for a liquid crystal display device, wherein the light amount of the light source is adjusted according to the width of the activated portion. 6. The light source control method for a liquid crystal display device according to claim 5, wherein the specific position on the screen is specified by input means to the screen. 7. The light source control method for a liquid crystal display device according to claim 5, wherein the specific position on the screen is a variable portion of display information on the screen. 8. The method according to claim 5, wherein the specific position on the screen is a window displayed on the screen.