JP2003114648A - Liquid crystal display device, computer device and its control method for driving lcd panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the power consumption of a liquid crystal display device by shortening a frame cycle for replotting picture display in an LCD (liquid crystal display) panel and lowering the operating frequency of the LCD panel. SOLUTION: This display device is provided with an LCD panel 11 and a graphic controller 13 controlling display in the LCD panel 11. When the suppressing of power consumption is performed in the display device, the graphic controller 13 shortens the frame cycle while fixing a refresh rate as it is by shortening a non-display cycle at the time of replotting a picture.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device and a drive control of a liquid crystal display panel in a computer device using the same.

[0002]

2. Description of the Related Art Today, notebook type personal computers (hereinafter abbreviated as PCs), which have the characteristics of space saving and excellent portability, have become widespread. A liquid crystal display device is widely used as a display device of this notebook PC. This type of liquid crystal display device generally has an LCD (Liquid Cry
stal display) A backlight, which is a planar light source for illumination, is arranged on the back surface of the stal display panel, and the liquid crystal surface having a predetermined spread is irradiated to a uniform brightness as a whole to form on the liquid crystal surface of the LCD panel. The visualized image is visualized. Also,
In a notebook PC, AC (Alternating Cu)
In addition to the rrent) power source, a direct current (DC) power source is also available as a power source used when carrying the mobile phone.
It is configured so that the C battery can be mounted on a PC and driven.

[0003]

Therefore, especially when using a DC power source, it has always been a technical subject to extend the continuous driving time by a DC battery as much as possible. For this reason, efforts are being made to reduce power consumption in each part of the PC, and even in a liquid crystal display device, when a DC power source is used, an LC power source is used as compared with an AC power source.
The brightness of the D panel is automatically lowered and the operating frequency (basic clock) is lowered.

By the way, when the screen is displayed on the LCD panel, it is necessary to redraw the screen a predetermined number of times in one second.
Drive the D panel. The drive frequency at this time is called a refresh rate (vertical synchronization frequency). here,
The refresh rate and the operating frequency are closely related, and the operating frequency is basically determined by the refresh rate of the LCD. For example, the display resolution is 14
When driving a LCD panel of 00 × 1050 dots at a refresh rate of 50 Hz, the operating frequency is 90 MHz.
Becomes Similarly, when the refresh rate is driven at 60 Hz, the operating frequency is 108 MHz. Therefore, if the operating frequency is simply lowered, the refresh rate of the LCD panel is lowered accordingly. For this reason, if the operating frequency is significantly reduced, flicker on the screen becomes noticeable.

Further, it is known that the flicker of the screen becomes inconspicuous by lowering the brightness of the LCD panel according to the lowering of the refresh rate of the LCD panel. This method reduces LC
There is also a limit to reducing the refresh rate of the D panel.

On the other hand, the longer the continuous driving time with the DC battery is, the more preferable it is. Therefore, further measures for suppressing the power consumption are required. The present invention has been made based on such a technical problem, and an object thereof is to realize further reduction of power consumption in a liquid crystal display device of a PC.

[0007]

According to the present invention, which achieves the above object, the operating frequency of the LCD panel is lowered and the power consumption is reduced by shortening the frame period for redrawing the image display on the LCD panel. To realize.
A liquid crystal display device of the present invention that realizes this includes an LCD panel and a graphic controller that controls the display on the LCD panel and shortens the frame period while fixing the refresh rate when suppressing power consumption. Characterize.

More specifically, this graphic controller shortens the frame period by shortening the non-display period when redrawing an image. Further, this graphic controller shortens the non-display period within the operable range of the plurality of LCD panels when any one of the plurality of LCD panels is to be controlled. Further, the graphic controller can individually shorten at least one of the non-display period in rewriting the image in the horizontal direction and the non-display period in rewriting the image in the vertical direction.

Another liquid crystal display device of the present invention is an LC
A D panel and a graphic controller for controlling display on the LCD panel are provided, and the graphic controller includes a display period corresponding to the display resolution of the LCD panel and a non-display period shortened with respect to a standard value. The feature is that the image is rewritten by.

Here, the graphic controller has identification information of the LCD panel to be controlled, and a period including a non-display period shortened within an operable range of the LCD panel specified based on the identification information. To rewrite the image.

Still another liquid crystal display device according to the present invention is an LC
A D panel and a graphic controller for driving the LCD panel are provided. The graphic controller is based on a predetermined refresh rate and an image update period shorter than a standard value within a range in which the LCD panel can operate. This LCD panel is driven at a set operating frequency.

Here, the graphic controller drives the LCD panel at an operating frequency set based on the shortened image update period by shortening the non-display period when rewriting the image.

Further, the present invention is realized as a computer device using the above liquid crystal display device as an output means. That is, in a computer device having an LCD panel as a display device, a timing table in which timing parameters for driving the LCD panel are registered, and drive control means for driving the LCD panel according to the timing parameters registered in the timing table. And the timing table includes a first timing parameter set as a standard value,
The second timing parameter in which the operating frequency is lowered by shortening the frame period in image display is registered.

Here, the drive control means drives the LCD panel according to the second timing parameter when the battery is driven by the power source. In addition, the second timing parameter shortens the frame period and lowers the operating frequency within a range in which the plurality of LCD panels to be used can operate.

The above computer device acquires the identification information of the LCD panel, and the LC specified by this identification information.
A configuration may further be provided that includes a timing parameter generating unit that generates the second timing parameter within a range in which the D panel can operate and registers the second timing parameter in the timing table. The timing parameter generating means uses, as identification information, EDID (Extended Display I) of the LCD panel.
dentification Data).

Further, the present invention is a drive control method for an LCD panel, which detects an event that means an operating state in which power consumption should be suppressed, and when this event is detected, the LCD panel is detected. It is characterized in that the frame cycle in image display is shortened while the refresh rate is fixed. More specifically, this LCD panel drive control method shortens the frame period by shortening the non-display period when rewriting an image on the LCD panel.

Furthermore, according to the present invention, the identification information of the LCD panel is acquired, and the L specified by the acquired identification information is acquired.
The present invention is characterized in that a timing parameter in which the operating frequency is lowered is generated by shortening a frame period in image display within a range in which the CD panel can operate, and the LCD panel is driven according to the generated timing parameter.

Further, the present invention can be realized as a program (for example, BIOS) for realizing the drive control method of these LCD panels by a computer. This program can be provided by being stored in a magnetic disk, an optical disk, a semiconductor memory, or another storage medium for distribution, or distributed via a network.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below in detail based on the embodiments shown in the accompanying drawings. In the present embodiment, the case where the present invention is applied to a notebook PC is taken as an example, but it goes without saying that the present invention can also be applied to a desktop PC equipped with a liquid crystal display device as a display means.

[First Embodiment] FIG. 1 is a diagram for explaining a schematic configuration of a notebook PC as a computer device according to a first embodiment of the present invention.
In FIG. 1, the notebook PC of the present embodiment is
The liquid crystal display device 10 and the PC main body 20 are provided.

The liquid crystal display device 10 is a TFT (Thin Film Transistor) in which a signal line, a gate line, and an amorphous silicon layer are formed between two glass substrates.
And an LCD panel 11 in which color filters and the like are laminated and which is further filled with liquid crystal to form a display screen, and a backlight 12 as a light source which is provided on the back side of the LCD panel 11 and emits planar light for illumination. It has and. The LCD panel 11 is provided with a graphic controller 13 that controls a screen to be displayed as a driving unit, and the graphic controller 13 includes a frequency control unit 14 that controls the refresh rate of the LCD panel 11. Further, the backlight 12 is provided with a backlight controller 15 that controls the illuminance of the light source.

The PC main body 20 includes a CPU 21, a non-volatile memory 22 storing predetermined data, and devices connected to the PC main body 20 as constituent elements for controlling display in the liquid crystal display device 10. And an event controller 23 that monitors the input of the event and outputs the event to each device.

FIG. 2 is a diagram for explaining a software configuration for driving and controlling the liquid crystal display device 10 in the notebook PC shown in FIG. In FIG. 2, the application 110 is stored in a storage device such as a magnetic disk attached to a notebook PC, is loaded into a main memory accessed by the CPU 21, and controls the CPU 21. Then, by the method of the present embodiment described later, a command for lowering the operating frequency to suppress the power consumption of the liquid crystal display device 10 and operating in the power saving mode is output. Here, application 11
0 outputs the command through the event controller 23 when an event which means that the operating state in which the power consumption should be suppressed is detected. At this time, some input operation by the user may be detected as an event, or the operating environment may be investigated at the time of start-up and the like and the presence of a specific operating environment such as DC battery drive may be detected as an event. The command output from the application 110 is an interface (API)
Video BIOS (Basic Input / Ou) via layer 120
tput System) 130 to induce processing.

The video BIOS 130 is stored in the non-volatile memory 22 and controls the CPU 21 to control the operation of the graphic controller 13. Further, the video BIOS 130 has a timing table 131, and based on the timing table 131, the operating frequency, the refresh rate, the display period and the non-display period (bl) during image rewriting
A timing parameter such as anking period) is determined and transmitted to the graphic controller 13. As a result, the graphic controller 13 drives the LCD panel 11 according to the received timing parameter.

The liquid crystal display device 10 thus constructed
Is controlled by the graphic controller 13
A screen based on the data transferred from the main body 20 is displayed on the LCD panel 11. At this time, the LCD panel 11
The frequency controller 14 of the graphic controller 13 is driven at a predetermined refresh rate to redraw the display screen a predetermined number of times per second. Further, the brightness of the display screen of the LCD panel 11 is set by controlling the light source illuminance of the backlight 12 by the backlight controller 15. The refresh rate and brightness setting values of the LCD panel 11 are stored in the nonvolatile memory 22.
When the notebook PC is started, the refresh rate and the brightness of the LCD panel 11 are set by referring to the set values stored in the non-volatile memory 22.

In the present embodiment, the operating frequency of the LCD panel 11 is lowered so that the liquid crystal display device 1 can be operated.
Power consumption at 0 is reduced. Here, if the operating frequency is simply lowered, the refresh rate of the LCD panel 11 is also lowered, and the flickering of the screen becomes noticeable. In order to avoid this, in the present embodiment, by shortening the non-display period when redrawing an image,
It is possible to reduce the operating frequency without reducing the refresh rate of the LCD panel 11. The details will be described below.

FIG. 3 shows a synchronization timing (Hsync) of a period (hereinafter referred to as an update cycle) required for rewriting an image in the horizontal direction in the LCD panel 11 which displays 1280 dots in the horizontal direction, and the update timing in the update cycle. It is a figure which shows the display state (DE1) of an image. Here, the update cycle indicated by the synchronization timing (Hsync) corresponds to a period required for rewriting the image once, that is, the number of clocks of the clock signal that defines the operating frequency.
The image display state (DE1) is displayed on the LCD panel 11
The display period and the non-display period in FIG.

As shown in FIG. 3, in DE1, Hs
In one cycle of sync, a non-display period of 408 dots is set for a display period of 1280 dots, which is 1688 dots in total. That is, in the LCD panel 11, in order to redraw the image of one line in the horizontal direction, the clock signal that defines the operating frequency is set to 1
This means that the number of clocks is sufficient to control the display of 688 dots. Here, the non-display period is a period in which the image inserted when updating the image is not displayed.
This is an essential timing parameter in the structure of the CRT display when the CRT display is used as the display device, but it is not essential when the LCD is used as the display device. However, today, a CRT display is used as a main display device of a PC together with an LCD, and a non-display period is provided in order to maintain compatibility with the CRT display.

By the way, in the notebook PC, in addition to the liquid crystal display device 10 which is mainly used, a display device (including a CRT display) by an external connection can be used. Therefore, the frequency controller 14 is provided in the graphic controller 13. There are those equipped with two CRTCs (CRT controllers). In this case, when the CRTC for controlling the liquid crystal display device 10 is used, compatibility with the CRT display need not be taken into consideration, and thus it is necessary to provide a non-display period suitable for the CRT display during the image update cycle. Absent. For example, in the liquid crystal display device 10 of the notebook PC, the non-display period is changed to 14
A resolution of 00 × 1050 dots is realized.

DE2 in FIG. 3 shows a state in which the resolution of 1400 dots in the horizontal direction is realized by changing the ratio of the display period and the non-display period in one cycle of Hsync. Referring to the figure, the non-display period is changed from the standard 408 dots to 2 with the 1 cycle of Hsync fixed to 1688 dots.
By shortening it to 88 dots, the display period is 1400
It has dots. The same operation is performed for the update cycle in the vertical direction, and the non-display period is shortened so that the operation frequency and the refresh rate are not changed.
A resolution of 400 × 1050 dots can be obtained.
Although the case where the graphic controller 13 has two CRTCs has been described here, the liquid crystal display device 1 does not use a CRT display as a display device.
If limited to 0, the same control can be performed even when the graphic controller 13 has only one CRTC.

As described above, when the display device to be used is limited to the liquid crystal display device 10, it is not necessary to consider the compatibility with the CRT display, so that the non-display period in the image update cycle can be expanded or contracted. . Considering this, the operating frequency is lowered while the refresh rate is fixed. FIG. 4 shows the same LCD panel 1.
3 is a diagram illustrating a conceptual process of lowering the operating frequency by using 1 (resolution 1400 × 1050 dots). In FIG. 4, column 1 shows the original operation mode of the LCD panel 11 (operation mode maintaining compatibility with the CRT display). That is, when driven at a resolution of 1280 × 1024 dots and a refresh rate of 60 Hz, the non-display period in the horizontal direction is 408 (1688-128).
0) dot, vertical non-display period is 44 (1068-
1024) line, and the operating frequency is 108 MHz.

Column 2 shows an operation mode in which only the resolution is expanded without changing the operation frequency and the refresh rate, as shown in DE2 of FIG. That is, 140
When driven at a resolution of 0 × 1050 dots and a refresh rate of 60 Hz, the operating frequency remains 108 MHz, but the horizontal non-display period is 288 (1688).
-1400) dots, vertical non-display period is 18 (1
068-1050) line.

Column 3 shows an operation mode in the case where the operating frequency is simply lowered as a pre-stage of the lowering of the operating frequency accompanied by the shortening of the non-display period according to the present embodiment. That is, with the resolution of 1400 × 1050 dots, the horizontal non-display period is 288 (1688-1400) dots,
The non-display period in the vertical direction is set to 18 (1068-1050) lines, and the refresh rate is reduced to 50 to 40 Hz, whereby the operating frequency is reduced to 90 to 72 MHz. Here, since the possible values of the refresh rate and the operating frequency differ depending on the type (difference of manufacturer or model) of the liquid crystal display device 10, these values are described with a width in the column 3. It is assumed that the screen flicker is suppressed by lowering the brightness of the LCD panel 11 at the same time as lowering the refresh rate. However, since the brightness of the LCD panel 11 is reduced and the visibility of the screen is deteriorated, there is a limit to the reduction of the operating frequency by this method. The flicker of the screen and the deterioration of the visibility due to the reduction of the brightness are characteristics that are subjectively recognized, but the refresh rate of about 50 to 40 Hz described in column 3 can be said to be the limit.

Column 4 shows an operation mode when the operating frequency is further lowered from the state of FIG. 3 by utilizing the shortening of the non-display period according to the present embodiment. That is, 1400x
1050 dot resolution and refresh rate 50-4
While holding 0 Hz, the horizontal non-display period is 30
By shortening the (1430-1400) dots and the non-display period in the vertical direction to 3 (1053-1050) lines, the operating frequency is lowered to 75-60. The lowering of the operating frequency due to the shortening of the non-display period will be described in more detail.

FIG. 5 shows the synchronization timing (Hsync1, 2) of the image update cycle in the horizontal direction and the display state (DE3, DE3) of the image in the horizontal direction corresponding to the operation modes of fields 3 and 4 in FIG. It is a figure which shows 4). In FIG. 5, DE3 corresponds to the operation mode of column 3, and DE4 corresponds to the operation mode of column 4. As shown in FIG. 5, in DE3, a display period of 1400 dots and a non-display period of 288 dots are set for one cycle of Hsync1, and the total is 1688 dots. The entire length is similar to DE1 and DE2 shown in FIG. On the other hand, in DE4, a display period of 1400 dots and a non-display period of 30 dots are set for one cycle of Hsync2, which is 1430 dots in total. Therefore, the total length of the image update cycle without changing the display period, that is, the number of clocks required for rewriting one horizontal line of the image once is shortened.
The same is true for the vertical display, which is
If the refresh rate indicating the frequency of image rewriting is fixed, it means that the operating frequency has decreased.

In this way, by shortening the non-display period accompanying redrawing of the image while maintaining the display resolution of the LCD panel 11, only the operating frequency of the LCD panel 11 is lowered while the refresh rate is fixed. be able to. And thereby, it becomes possible to reduce the power consumption of the liquid crystal display device 10. In the above example, L having a display resolution of 1400 × 1050 dots is used.
Although the CD panel 11 has been described as an example, it goes without saying that the same operation can be performed on the LCD panel 11 having another display resolution. Also, the LCD panel 11
With the refresh rate of 60 Hz, the method of reducing the operating frequency by shortening the non-display period according to the present embodiment may be used, or the display resolution may be 1280 × 10.
The method according to the present embodiment may be used in the 24-dot state. Further, in the above example, the non-display period in the horizontal direction is shortened to 30 dots and the non-display period in the vertical direction is shortened to 3 lines to reduce the operating frequency close to the limit by this method. It is also possible to set the width to be narrow. For example, if the horizontal non-display period is 200
Assuming that (1600-1400) dots and the vertical non-display period are 12 (1062-1050) lines, the refresh rate is 50-40 Hz and the operating frequency is 85-85.
It can be 68 MHz.

The method for suppressing the power consumption of the liquid crystal display device 10 according to the present embodiment described above can be realized in the notebook PC shown in FIGS. 1 and 2 as follows. First, the timing table 1 of the video BIOS 130 stored in the non-volatile memory 22.
In 31, the parameters for the power saving mode are registered in addition to the parameters for normal operation control. LCD
When the display resolution of the panel 11 is 1400 × 1050, for example, the information described in the column 2 of FIG. 4 can be registered as the parameter for normal operation control, and the parameter in the power saving mode can be registered. For example, the information described in the column 4 of FIG. 4 can be registered.
In the initial state, the video BIOS 130 has the graphic controller 13 based on the parameters for normal operation control registered in the timing table 131.
Control the operation of. As a result, the graphic controller 13 drives the LCD panel 11 at the original operating frequency and refresh rate.

When the operating state in which the power consumption should be suppressed is reached (for example, when the operation mode is switched to the DC battery drive), the application 110 detects this and outputs a command for operating in the power saving mode. Then, the video BIOS 130 that has received the command refers to the timing table 131 and controls the operation of the graphic controller 13 based on the parameters in the power saving mode. As a result, the graphic controller 13 causes the LCD panel 11 to operate at the lowered operating frequency for the power saving mode.
Are driven to rewrite the image at the corresponding refresh rate and update period. At this time, column 3 in FIG.
The method of lowering the refresh rate described with reference to can also be used together. In this case, the backlight controller 15 controls the drive of the backlight 12 to reduce the brightness of the LCD panel 11 and suppress the flicker of the screen.

By the way, when the operating frequency is lowered while the refresh rate is fixed, the range depends on how much the non-display period can be shortened. Here, the non-display period can be theoretically shortened to 0,
Actually, there is a fixed lower limit depending on the display capacity of the LCD panel 11 and the processing capacity of the graphic controller 13. The value varies depending on the type of LCD panel 11 due to the difference in the configuration of the IC circuit used. Therefore, with respect to the plurality of LCD panels 11 for which the operation frequency is controlled according to the present embodiment, the horizontal and vertical update cycles (Hsync, Vsync) are set.
c) The specifications such as the minimum possible value of the non-display period are compared. Then, a value that can be realized by all the LCD panels 11 and that can reduce the operating frequency most is defined as a representative specification, and is registered in the timing table 131. This makes it possible to implement operation control in the power saving mode that can be used for all of the plurality of LCD panels 11.

FIG. 6 shows four LCD-A to LCD-D.
6 is a chart showing representative specifications obtained by comparing specifications of LCD panels 11 of various types. In FIG. 6, LC
As the specifications of the D panel 11 and the graphic controller 13, the minimum value, the standard value, and the maximum value of the update cycle in both the vertical direction and the horizontal direction, and the minimum value, the standard value, and the maximum value of the operating frequency are described. Further, the non-display period, the front porch and the back porch when the minimum value of the update cycle is taken are described. Referring to FIG. 6, the LCD-D has the lowest spec performance in the vertical direction. Further, in the horizontal direction, the specification performance of the LCD-A is the lowest at the minimum possible update period and the non-display period, and the specification performance of the LCD-D is the lowest at the values of the front porch and the back porch. Therefore,
The representative specifications are defined by selecting these values, and the operating frequency in the power saving mode is determined based on the representative specifications. As shown in FIG. 6, the determined operating frequency is the LC with the largest possible minimum operating frequency.
Since it is larger than the value of D-A, it can be seen that the power saving mode with the determined operating frequency can be realized in all LCD panels 11.

[Second Embodiment] Next, a plurality of LCDs
An embodiment will be described in which drive control of liquid crystal display is performed by individual settings corresponding to the panel 11. FIG. 7 is a diagram for explaining a schematic configuration of a notebook PC as a computer device according to the second embodiment, and FIG. 8 drives a liquid crystal display device 10 in the notebook PC shown in FIG. It is a figure explaining the software structure for controlling. 7 and 8, the same components as those of the first embodiment shown in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted.

Referring to FIG. 7, the notebook PC according to the present embodiment has a graphic controller 71.
LCD panel identification section 72 for identifying the LCD panel 11
It is different from the first embodiment in that Further, in FIG. 8, in the present embodiment, the system BIO
S140 recognizes the LCD panel 11 to be used based on the identification result of the LCD panel identification unit 72, and performs the video BIO.
Necessary settings are made in S130.

As a method of identifying the LCD panel 11, the EDID originally added to the LCD panel 11 is used.
(Extended Display Identification Data) can be used, or an ID (Identification Data) uniquely assigned to each LCD panel 11 to be used can be used. When using EDID, LCD panel 11
The EDID stored in the memory provided above is generally read and used, but the memory storing the EDID may be anywhere between the LCD panel 11 and the LCD panel identification section 72, and the graphic controller 7
It is also possible to provide it on the display device 1 or to interpose a small board having such a memory on a cable connecting the LCD panel 11 and the graphic controller 71.

When a unique ID is assigned to the LCD panel 11, a pin for identifying an ID is provided on the LCD panel 11, and a high / high signal is provided for each type of the LCD panel 11.
An ID can be given by assigning a row.
In this case, for example, if the LCD panel 11 to be used is 2
If it is a type, it can be identified by 1-bit information. In addition, the LCD panel 11 and the graphic controller 71
One of the signal lines in the cable connecting to and is used for ID identification, and the high / low of the signal on the signal line
It is also possible to have. Further, a memory storing the uniquely assigned ID is provided at an arbitrary position such as on the LCD panel 11, the graphic controller 71, or a cable connecting the LCD panel 11 and the graphic controller 71, and the ID stored in the memory is used. The LCD panel 11 can also be identified.

In this embodiment, as in the first embodiment, the non-display period in the update cycle of the image displayed on the LCD panel 11 is shortened, so that the LCD panel 11 can be displayed without lowering the refresh rate. Reduce the operating frequency to reduce power consumption. Here, as described above, the value that can reduce the non-display period is the LCD panel 1
It varies according to the type of 1. According to this embodiment,
By identifying the type of the LCD panel 11 to be used, it is possible to realize the most effective power saving mode according to the spec performance of the LCD panel 11.

For example, when the four types of LCD panels 11 shown in FIG. 6 are used, in the first embodiment, various parameters are set in order to set the power saving mode that can be realized by all the LCD panels 11. In the above, the representative specification is defined using the value of the LCD panel 11 having the lowest specification performance, and the operating frequency in the power saving mode is determined based on the representative specification. However, LCD-B
And LCD-C are LCD-A for all parameters.
In some parameters of LCD and LCD-D, the spec performance exceeds the typical spec. Therefore, by identifying the type of the LCD panel 11 and determining the operating frequency in the power saving mode individually adapted to these spec performances, the individual LCD panel 11 is determined.
It is possible to reduce the power consumption to the maximum.

In order to individually set the operating frequency in the power saving mode according to the type of the LCD panel 11, it is not enough to identify the type of the LCD panel 11, and it is not enough to identify the type of the LCD panel 11 to be used. Need to get information about specs. Therefore, information regarding the specifications of all LCD panels 11 as shown in FIG. 6 is stored as a table in the memory of the PC main body 20, and the table is referred to based on the acquired EDID or ID to consume the information. A possible method is to set the operating frequency that can reduce the power most. In this case, the video BIOS 13
0 or the system BIOS 140 may be stored in the non-volatile memory 22. However, since the non-volatile memory 22 generally has a small storage capacity, it is preferable to separately provide a memory for storing the table. Since information such as the operating frequency, refresh rate, and non-display period of the LCD panel 11 in normal times can be obtained from the EDID, the nonvolatile memory 22 stores only the difference from these values in the power saving mode and the calculation formula. Alternatively, the operating frequency and the non-display period in the power saving mode may be calculated based on these pieces of information in the EDID acquired from the LCD panel 11.

FIG. 9 is a flow chart for explaining the operation of this embodiment when the notebook PC is started. Here, an operation when the EDID is read from the memory provided on the LCD panel 11 to identify the LCD panel 11 will be described as an example. As shown in FIG.
When C boots (step 901), the system BIOS
140 instructs the video BIOS 130 to identify the LCD panel 11 (step 902). Video BIOS 1
30 receives the instruction and the graphic controller 7
1 to control the LCD panel identification section 72 of the LCD panel 1
The EDID of the LCD panel 11 is obtained from the memory on the computer 1 and passed to the system BIOS 140 (step 90).
3).

The system BIOS 140 receives the received E
The type of the LCD panel 11 is specified based on the DID, and parameters such as the operating frequency and the non-display period that can reduce the power consumption of the LCD panel 11 are determined (step 904). Then, the determined value is used as a parameter in the power saving mode as the video BIOS 130.
Is registered in the timing table 131 (step 90).
5).

As described above, when the PC is started, the LC
The parameters of the operation control in the power saving mode are determined according to the identification result of the D panel 11, and the video BIOS 13
It will be registered in the timing table 131 of 0. After that, similarly to the first embodiment, in the initial state, the operation control of the graphic controller 71 is performed based on the parameters for the operation control in the normal state, and the power saving mode is performed according to the command from the application 110. The operation of the graphic controller 71 is controlled on the basis of the parameters in the above.

Although the present invention has been described above with reference to the first and second embodiments, the notebook type P shown in FIGS.
The configuration of C is one of the hardware that realizes the present embodiment.
It is needless to say that any configuration may be adopted without departing from the gist of the present invention. For example, although the liquid crystal display device 10 is configured to include the graphic controllers 13 and 71 in FIGS. 1 and 7, the graphic controllers 13 and 71 are configured to include the PC main body 2.
The configuration may be included in 0. As described above, the first and second embodiments can be applied to a desktop PC including the liquid crystal display device 10 as a display unit.

In the first and second embodiments described above,
Although the non-display period is shortened for both the horizontal scanning and the vertical scanning in rewriting the image on the LCD panel 11, the operation can be performed by shortening the non-display period in either one. Lower the frequency,
Power consumption can be reduced. Therefore, the degree of reduction in power consumption can be controlled by independently reducing the non-display period in the horizontal direction and reducing the non-display period in rewriting an image in the vertical direction.

[0053]

As described above, according to the present invention,
Since the operating frequency can be lowered while the refresh rate is fixed in the LCD panel of the liquid crystal display device, the power consumption can be effectively suppressed without causing the screen flicker. In addition, this makes it possible to extend the continuous drive time even when driven by a DC battery.

[Brief description of drawings]

FIG. 1 is a diagram for explaining a schematic configuration of a notebook PC as a computer device according to a first embodiment.

FIG. 2 is a diagram illustrating a software configuration for driving and controlling a liquid crystal display device according to the first embodiment.

FIG. 3 is a diagram showing a synchronization timing of an image update cycle in the horizontal direction of the LCD panel and a display state of the image in the update cycle.

FIG. 4 is a diagram illustrating a conceptual process of reducing the operating frequency of an LCD panel.

FIG. 5 corresponds to the operation modes of columns 3 and 4 of FIG.
The synchronization timing of the image update cycle in the horizontal direction,
It is a figure which shows the display state of the image in the said update period.

FIG. 6 is a table showing representative specifications obtained by comparing specifications of four types of LCD panels.

FIG. 7 is a diagram for explaining a schematic configuration of a notebook PC as a computer device according to the second embodiment.

FIG. 8 is a diagram illustrating a software configuration for driving and controlling a liquid crystal display device according to the second embodiment.

FIG. 9 is a flowchart illustrating the operation of the present embodiment when the notebook PC is activated.

[Explanation of symbols]

10 ... Liquid crystal display device, 11 ... LCD panel, 12 ... Backlight, 13, 71 ... Graphic controller, 1
4 ... Frequency control unit, 15 ... Backlight controller,
20 ... PC main body, 21 ... CPU, 22 ... Non-volatile memory, 23 ... Event controller, 72 ... LCD panel identification part, 110 ... Application, 120 ... Interface (API) layer, 130 ... Video BIOS,
131 ... Timing table, 140 ... System BIO
S

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Rieko Kataoka             1623 1423 Shimotsuruma, Yamato-shi, Kanagawa Japan             BM Co., Ltd. Daiwa Office (72) Inventor Yasumasa Takeda             1623 1423 Shimotsuruma, Yamato-shi, Kanagawa Japan             BM Co., Ltd. Daiwa Office (72) Inventor Masaki Kobayashi             1623 1423 Shimotsuruma, Yamato-shi, Kanagawa Japan             BM Co., Ltd. Daiwa Office (72) Inventor Yoshimasa Kiyotani             1623 1423 Shimotsuruma, Yamato-shi, Kanagawa Japan             BM Co., Ltd. Daiwa Office F-term (reference) 2H093 NA35 NC16 NC29 ND10 ND39                 5C006 AA01 AF13 AF44 AF51 AF52                       AF53 AF61 AF69 AF71 BB11                       BC16 BF16 BF45 FA47                 5C080 AA10 BB05 DD26 JJ02 JJ04                       JJ07

Claims (18)

[Claims] 1. An LCD (Liquid Crystal Display) panel and, when controlling display on the LCD panel and suppressing power consumption, shorten a frame cycle in image display while fixing a refresh rate of the LCD panel. A liquid crystal display device comprising a graphic controller. 2. The liquid crystal display device according to claim 1, wherein the graphic controller shortens the frame period by shortening a non-display period when redrawing an image. 3. The graphic controller shortens the non-display period within a range in which the plurality of LCD panels can operate, when any one of the plurality of LCD panels is to be controlled. 2. The liquid crystal display device according to item 2. 4. The graphic controller shortens at least one of a non-display period during rewriting of an image in the horizontal direction and a non-display period during rewriting of an image in the vertical direction. Liquid crystal display device. 5. An LCD (Liquid Crystal Display) panel, and a graphic controller for controlling display on the LCD panel, wherein the graphic controller has a display period corresponding to a display resolution of the LCD panel and a standard value. A liquid crystal display device, characterized in that an image is rewritten during a period including a shortened non-display period. 6. The period in which the graphic controller has identification information of an LCD panel that is a control target, and includes the non-display period shortened within an operable range of the LCD panel specified based on the identification information. The liquid crystal display device according to claim 5, wherein the image is rewritten by. 7. An LCD (Liquid Crystal Display) panel and a graphic controller for driving the LCD panel, wherein the graphic controller has a predetermined refresh rate and a standard value within a range in which the LCD panel can operate. A liquid crystal display device, characterized in that the LCD panel is driven at an operating frequency set based on a shortened image update period. 8. The graphic controller drives the LCD panel at an operating frequency set on the basis of an update cycle of the image shortened by shortening a non-display period when redrawing an image. Liquid crystal display device. 9. An LCD (Liquid Crystal) as a display device.
A computer device including a display panel, comprising: a timing table in which timing parameters for driving the LCD panel are registered; and drive control means for driving the LCD panel in accordance with the timing parameters registered in the timing table. The computer is characterized in that the timing table registers a first timing parameter set as a standard value and a second timing parameter in which an operating frequency is lowered by shortening a frame period in image display. apparatus. 10. The computer device according to claim 9, wherein the drive control means drives the LCD panel according to the second timing parameter when driven by a battery. 11. The second timing parameter registered in the timing table shortens the frame period and lowers the operating frequency within a range in which a plurality of LCD panels to be used can operate. The computer apparatus according to claim 9, wherein the computer apparatus is a computer apparatus. 12. Acquiring identification information of the LCD panel, generating the second timing parameter within a range in which the LCD panel specified by the identification information can operate,
The computer apparatus according to claim 9, further comprising a timing parameter generating unit that registers the timing table. 13. The timing parameter generating means is an EDID (Extended Display I) of the LCD panel.
13. The computer device according to claim 12, characterized in that dentification data) is acquired as identification information. 14. A drive control method for an LCD (Liquid Crystal Display) panel, which detects an event indicating that an operating state in which power consumption is to be suppressed, and when the event is detected, A drive control method for an LCD panel, wherein a frame cycle in image display is shortened while fixing a refresh rate of the LCD panel. 15. The LC according to claim 14, wherein the frame period is shortened by shortening a non-display period when redrawing an image on the LCD panel.
Drive control method of D panel. 16. An operation is performed by acquiring identification information of an LCD (Liquid Crystal Display) panel and shortening a frame period in image display within a operable range of the LCD panel specified by the acquired identification information. A drive control method for an LCD panel, comprising: generating a timing parameter having a reduced frequency, and driving the LCD panel according to the generated timing parameter. 17. An LCD (Liquor) is controlled by controlling a computer.
id Crystal Display) a program for driving the panel, the process of detecting an event that means that the operating state should be reduced power consumption, and the refresh rate of the LCD panel when the event is detected. A program for causing the computer to execute a process of shortening a frame period in image display while fixing the. 18. An LCD (Liquor) is controlled by controlling a computer.
id Crystal Display) is a program for driving a panel, the process of acquiring the identification information of the LCD panel, and the frame cycle in image display within the operable range of the LCD panel specified by the acquired identification information. And a program for causing the computer to execute a process of generating a timing parameter in which an operating frequency is reduced by shortening the operation frequency, and a process of driving the LCD panel according to the generated timing parameter.