JP2002287707A - Liquid crystal display device and system provided therewith - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal display device capable of reducing the power consumption. SOLUTION: The liquid crystal display device capable of displaying a picture in 65,536 colors in response to pixel data of 16 bits has a 1st display mode for displaying a picture in 65,536 colors equal to the 1st number of colors in response to the pixel data of the 1st number of bits. The display device performs frame displaying (9) of the 2nd number of colors less than the 1st number of colors by using the pixel data of the 8 higher order bits among the 16 bits, and also performs inter-frame thinned-out scanning control (8) by using the pixel data part of the 3rd number of bits except the 2nd number of bits in the 1st number of bits, and thereby varies the brightness of pixels for every display frame of the above.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a liquid crystal display device,
The present invention relates to a system such as a mobile terminal and a computer system using the liquid crystal display device.

[0002]

2. Description of the Related Art A liquid crystal display device of a portable terminal, a liquid crystal display system using the same, and a portable terminal or the like equipped with the liquid crystal display system are usually carried and used. In this case, only 256 colors are displayed. A battery or the like is often used as a power source when going out. In such a case,
Since a battery is used as a power source, there is an upper limit on the amount of power that can be used. For this reason, it is desired to save power in order to extend the usable time even a little. Since the battery usage of the image display means in a mobile terminal or the like equipped with the liquid crystal display system of the mobile terminal often occupies a relatively large part of the entire mobile phone, the appropriate power saving of the image display means is reduced. It is useful to plan.

As a technical means for appropriately saving power of such an image display means, there is a portable type which controls the brightness of a backlight of a liquid crystal display device depending on whether a power supply is an internal battery such as a battery or an external power supply. (Japanese Patent Application Laid-Open Nos. 7-41075 and 2000-125)
163). In these prior arts, two power consumptions are reduced.
Display of 56 colors or power consumption increases but 6553
The display is limited to one of the six colors, and power saving by switching the number of display colors has not been performed.

[0004]

[0004] Mobile phones are also required to be multi-colored in display, for example, as content has been enhanced and cameras with cameras have appeared. On the other hand, current consumption increases with the pursuit of multi-color display, so when displaying a still image, displaying a moving image, or when using a low battery (when the remaining battery power is less than a certain level), when turning on the backlight, or when turning off the backlight It is necessary to save power appropriately according to the operation state such as time.

Therefore, an object of the present invention is to provide a liquid crystal display device capable of reducing power consumption. Also,
Another object of the present invention is to provide a system such as a portable terminal that can reduce power consumption according to an operation state by using such a liquid crystal display device.

[0006]

In order to achieve the above object, according to the present invention, a liquid crystal display device capable of displaying an image in a first number of colors in response to pixel data of a first number of bits. Performs frame display of a second color number smaller than the first color number using the pixel data portion of the second bit number of the first bit number, and performs the frame display of the second color number smaller than the first color number. A first display mode in which frame thinning scan control is performed using a pixel data portion having a third bit number other than the second bit number.

In the liquid crystal display device of the present invention, further, in response to pixel data of a second bit number smaller than the first bit number, an image is displayed in a second color number smaller than the first color number. , A second display mode for performing

Further, a system according to the present invention includes the above-mentioned liquid crystal display device. According to the present invention, the system can be further configured such that the selection between the first and second display modes is made depending on at least one operation state of the portable terminal including the liquid crystal display device. Here, the at least one operation state is an operation state relating to a type of image including a still image or a moving image, an operation state relating to whether or not a backlight of the liquid crystal display device is turned on, and an operation relating to a remaining voltage of a battery of the portable terminal. Any one of a state, an operation state related to the presence or absence of a display mode instruction signal indicating the first or second display mode generated in the mobile terminal, or any combination thereof may be included.
Further, according to the present invention, the system can be a portable terminal.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram illustrating a configuration of a mobile terminal including a liquid crystal display device according to an embodiment of the present invention. The liquid crystal display device of the portable terminal includes the following elements and signals.

1) An 8-bit (Bit) (RGB = 332) pixel (P) output from the liquid crystal controller 1
IXEL) LCD driver 12 with a built-in 256-color RAM that constitutes control means for controlling display based on data; 3) a backlight 14 that emits light from the rear side to provide brightness so that the display on the LCD 13 (display portion) is bright and easy to see; 4) a backlight ON / OFF signal for controlling light emission of the backlight 14 6, 5) a battery 3 for driving the liquid crystal display device of the portable terminal, a battery voltage detecting circuit 4, which constitutes a battery state detecting means for detecting the battery voltage of the battery 3, 6) a CPU 2 for performing each control Central control circuit), 7) Color number switching signal for switching between still image and moving image 5, 8) Liquid crystal controller 1, 9) Liquid crystal controller The battery voltage remaining amount detection circuit 7 detects the remaining battery voltage value detected by the battery voltage detection circuit 4 and checks whether the battery is a low battery (when the battery remaining amount is below a certain level). 16 bits (R) from the central control circuit
GB = 565) / Display RAM for storing PIXEL data
11, 11) The 16 bits (R) stored in the display RAM 11
GB = 565) / Lower B of each RGB of PIXEL data
frame thinning information 16 and 12 generated by growing frame thinning data 15 with 8 bit (RGB = 233) data of it, and 12) changing the brightness of PIXEL for each display frame using the frame thinning information 16 (for each pixel) ), The frame thinning scan control unit 8, 13 for expressing the intermediate color with the average value. 13) Transfer 8 bit (RGB = 332) data, which is the upper bit (RGB = 332) of each RGB, to the LCD driver. RGB of bit = 33
2) The color reduction circuit 9 for generating "", 14) In response to the select signal 17 output from the two OR circuits 18, the frame thinning scan control 8 is performed.
Bit (RGB = 332) / PIXEL data or 8 bits (RGB = RGB = “transfer data” from the color reduction circuit 9)
332) Selector 10 for outputting either of / PIXEL data. Next, the operation of the liquid crystal display device of the portable terminal will be described with reference to FIG. First, 16-bit / PIXEL data from the CPU 2 (central control circuit) is stored in the display RAM 11 of the liquid crystal controller 1 (S1). Next, the battery voltage of the battery 3 is detected by the battery voltage detection circuit 4, and the detected remaining battery voltage value is detected by the remaining battery voltage detection circuit 7, and the low battery (the remaining battery power is detected). (At a certain time or less) is checked (S2). Here, when it is detected that the battery is low (when the remaining battery power is below a certain level) (the battery voltage remaining signal is high), OR
The circuit 18 generates a high select signal 17. This signal switches the selector 10 to the color reduction circuit 9 side,
16 bits (RGB = 565) / 8 bits which are the upper bits (RGB = 332) of each RGB of the PIXEL data
By storing (RGB = 332) data, that is, “transfer data” of the color reduction circuit 9, in the display RAM 11,
Data for one screen is written to the display RAM of the LCD driver 12 (S6). Thereby, the LCD driver 12
Under the control of, an image is displayed on the LCD 13 (display portion) by displaying 256 colors (S7).

On the other hand, when the detected remaining battery voltage value is not a low battery (when the remaining battery power is below a certain level), if the color number switching signal 5 indicates a moving image (high) (0 in S3), 0 is set.
The R circuit 18 generates a high select signal 17 to switch the selector 10 to the color reduction circuit 9 side. Thus, by storing the transfer data in the display RAM 11, data for one screen is written to the display RAM of the LCD driver 12 (S6) (S6). Thus, under the control of the LCD driver 12, an image is displayed on the LCD 13 (display portion) in a 256-color display (S7).

On the other hand, in step S3, if the image is a still image (the number-of-colors switching signal is low) and the backlight 14 is off (the backlight ON / OFF signal is high), the OR circuit 18 The selector 10 is switched to the color reduction circuit 9 by generating a high select signal. As a result, steps S6 and S7 are executed in the same manner as described above, and an image is displayed in 256 colors.

On the other hand, a still image and the backlight 1
If 4 is lit (backlight ON / OFF signal is low), the OR circuit 18 generates a low select signal 17. With this signal, the selector 10 is switched to the scan control unit 8 side. As a result, frame thinning scan control is performed. That is, “transfer data” (image data to be displayed in 65536 colors) via the scan control unit 8 is stored in the display RAM 11 (S5). Accordingly, 16 bits (RGB = 565) / 8 bits (RGB = lower bit) of each RGB of the PIXEL data.
233) The frame thinning data 15 is cultivated by the data, and in the cultivated frame thinning information 16, the transfer data of 8 bits (RGB = 332) which is the upper 8 bits indicates the brightness of PIXEL for each display frame. The intermediate color is expressed by the average value. As a result, 65
536 colors are displayed (S7).

According to the present invention, an image of 256 colors is displayed by the transfer data when the battery is low, the moving image is displayed, or the backlight 14 is turned off. As a result, when the data for one screen has been written to the display RAM of the LCD driver 12, the liquid crystal controller 1 enters a standby state, and the power consumption of the liquid crystal controller 1 can be reduced. On the other hand, in the display of 65536 colors by the scan control, the liquid crystal controller 1 does not enter the standby state. (For 65536 colors, it is necessary to always perform the scan control and write the data for one screen to the display RAM of the LCD driver. For).

FIG. 3 is a table showing various operating states of a battery voltage remaining amount signal, a color number switching signal, a backlight ON / OFF signal, and states of a select signal. As can be seen from this, only when the remaining battery voltage is OK, the image is a still image, and the backlight is on, the select signal becomes low, and 65536 color display is performed. In all other cases, 256 colors are displayed to reduce power consumption.
That is, when the battery is in the low battery state, it is effective to reduce the power consumption. In the case of a moving image, since rewriting occurs, there is no problem in terms of image even if the number of colors is reduced compared to a still image. On the other hand, a still image is preferably displayed with a large number of colors because rewriting does not occur. Further, since the backlight is normally controlled to be turned on automatically as required, when the backlight is turned off, for example, when the display unit is not active, a 256-color display with low power consumption is performed.

In the embodiment of the present invention described above, correspondence of RGB of 16-bit data (allocation of RGB)
Is RGB = 565, and the upper 8 bits of 16-bit data
Bit data (RGB = 332) and each lower 8-bit data (RGB = 233) are taken as an example, but the assignment of Bit can be arbitrarily changed.

[0017]

According to the present invention described above, display of a fixed number of colors can be performed with relatively low power consumption in a liquid crystal display device. According to the present invention, a portable terminal using such a liquid crystal display device, a computer,
In a system including a system, etc., by appropriately using a plurality of display modes having different power consumption and the number of display colors, by appropriately selecting a display mode according to the operation state of the system, a required color can be obtained. Image display by number can be provided with low power consumption.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of a liquid crystal display device of a portable terminal according to the present invention.

FIG. 2 is a flowchart showing the operation of the mobile terminal shown in FIG. 1;

FIG. 3 is a table showing various operation states and select signal states in the portable terminal shown in FIG. 2;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Liquid crystal controller 2 CPU 3 Battery 4 Battery voltage detection circuit 7 Battery voltage remaining amount detection circuit 8 Scan control part 9 Color reduction circuit 10 Selector 13 LCD (display part) 12 LCD driver (256 color RAM built-in driver) 14 Backlight 15 Frame thinning Data 18 OR circuit

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G09G 3/20 642 G09G 3/20 642J 650 650M 680 680S F-term (Reference) 2H088 EA22 MA20 2H093 NA61 NC50 NC56 NC58 ND17 ND39 NE10 NG20 5C006 AA22 AC21 AF01 AF44 AF53 AF69 AF85 BB11 BC16 FA47 5C080 AA10 BB05 CC03 DD26 EE30 FF09 GG12 JJ02 JJ07 KK47

Claims (9)

[Claims] 1. A liquid crystal display device capable of displaying an image in a first number of colors in response to pixel data of a first number of bits, wherein a second bit of the first number of bits is provided. A frame display of a second color number smaller than the first color number is performed using the pixel data portion of the second color number, and a pixel of a third bit number other than the second bit number of the first bit number is displayed. A liquid crystal display device comprising: a first display mode for performing frame thinning scan control using a data portion. 2. The liquid crystal display device according to claim 1, further comprising: the second color number being less than the first color number in response to the pixel data having the second bit number less than the first bit number.
A liquid crystal display device comprising: a second display mode for displaying an image by the number of colors. 3. A system comprising the liquid crystal display device according to claim 2. 4. The system according to claim 3, further comprising: selecting between the first and second display modes depending on at least one operation state of the mobile terminal including the liquid crystal display device. A system. 5. The system according to claim 4, wherein the at least one operation state is an operation state relating to an image type including a still image or a moving image.
A system. 6. The system according to claim 4, wherein the at least one operation state includes an operation state regarding whether or not a backlight of the liquid crystal display device is turned on. 7. The system according to claim 4, wherein the at least one operation state is an operation state related to a remaining voltage of a battery of the portable terminal.
A system. 8. The system according to claim 4, wherein the at least one operation state is a display mode instruction that indicates the first or second display mode generated in the portable terminal. Operating status related to the presence or absence of a signal. 9. The system according to claim 3, wherein said system is a portable terminal.