KR101310311B1 - Backlight device and liquid crystal display device having the same - Google Patents

Abstract

A backlight device that emits light having a brightness adjusted according to the gray level of the image and the

A liquid crystal display device having a is disclosed. The liquid crystal display displays an image using liquid crystal. The timing controller provides the image data supplied from the outside to the liquid crystal display, and the light source controls the light in the liquid crystal display. The light source controller controls the light source unit to supply a driving current adjusted according to the gray level of the image data. Accordingly, the power consumption can be reduced by providing the liquid crystal display panel with light having the luminance automatically adjusted according to the gray level in consideration of the gray level of the input image.

Backlight, Mobile Phone, Driving Current, Luminance, Gradation, Video, Menu, Button Key

Description

BACKLIGHT DEVICE AND LIQUID CRYSTAL DISPLAY DEVICE HAVING THE SAME

1 is an exploded perspective view illustrating a liquid crystal display according to an exemplary embodiment of the present invention.

2 is a graph illustrating luminance characteristics for each gray level of an image according to an image type.

3 is a graph illustrating the magnitude of a light source driving current applied according to the type of an image according to an embodiment of the present invention.

4 is a graph illustrating the magnitude of a light source driving current applied according to the type of an image according to another exemplary embodiment of the present invention.

5 is a block diagram illustrating a liquid crystal display according to an exemplary embodiment of the present invention.

6 is a block diagram illustrating an example of the timing controller and the light source controller illustrated in FIG. 5.

FIG. 7 is a block diagram illustrating another example of the timing controller and the light source controller illustrated in FIG. 5.

8 is a block diagram illustrating another example of the timing controller and the light source controller illustrated in FIG. 4.

<Description of the symbols for the main parts of the drawings>

10: flexible circuit board 100: timing control unit

110: latch 120: graphics memory

200: data driver 30: light guide plate

300: gate driver 40: storage container

400: liquid crystal display panel 50: optical sheet

500: light source control unit 510: counter

520, 560: comparison unit 530, 570: current control unit

540: first adder 550: second adder

60: liquid crystal display panel 600: light source unit

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a backlight device and a liquid crystal display device having the same, and more particularly, to a backlight device for emitting light having luminance adjusted according to the gray level of an image, and a liquid crystal display device having the same.

In general, a liquid crystal display device displays an image corresponding to the image information on a screen by adjusting the light transmittance of the liquid crystal according to the image information. To this end, the liquid crystal display panel provided in the liquid crystal display device includes a thin film transistor for switching liquid crystal cells arranged in a matrix form and image information to be supplied to each liquid crystal cell corresponding to the liquid crystal cells. transistor: switching elements such as TFT).

The driving device of the liquid crystal display panel controls the switching elements so that the image information can be supplied corresponding to the liquid crystal cells. In addition, the driving device of the liquid crystal display panel suppresses a phenomenon in which an image deteriorates due to flickering or afterimage, and lowers the driving voltage of the liquid crystal display panel to a positive (+) and negative (−) image information at a constant voltage level. ) Control to have polarity.

On the other hand, in a mobile phone employing a liquid crystal display panel, the power consumed by the liquid crystal display panel and the driving IC driving the liquid crystal display panel is about 20 mW or less, while the power consumption of the backlight device that provides light to the liquid crystal display panel is It is about 300mW or more.

The power consumption of the backlight device has a problem of increasing the discharge speed of the battery provided in the mobile phone.

Accordingly, the technical problem of the present invention is to solve such a conventional problem, and an object of the present invention is to provide a backlight device that emits light having luminance adjusted according to the gray level of an image.

Another object of the present invention is to provide a liquid crystal display device having the above-described backlight device.

In order to achieve the above object of the present invention, a backlight device includes a light source unit and a light source controller, and supplies light to a liquid crystal display panel displaying an image using a liquid crystal. The light source unit provides light to the liquid crystal display panel. The light source controller controls the light source unit to supply a driving current adjusted according to the gray level of the image data supplied to the liquid crystal display panel.

In one embodiment, the light source unit includes a light emitting diode.

In one embodiment, the light source controller controls the light source unit to supply a relatively small driving current when the image data is high gray, and the light source unit so that a relatively large driving current is supplied when the image data is low gray. To control. The light source controller controls the light source unit such that a relatively medium driving current is supplied when the image data is a halftone. Here, the high gradation includes a button key image, the low gradation includes a video, and the middle gradation includes a menu image.

In order to achieve the above object of the present invention, a liquid crystal display according to an exemplary embodiment includes a liquid crystal display, a timing controller, a light source, and a light source controller. The liquid crystal display displays an image using liquid crystal. The timing controller provides the image data supplied from the outside to the liquid crystal display, and the light source controls the light in the liquid crystal display. The light source controller controls the light source unit to supply a driving current adjusted according to the gray level of the image data.

In one embodiment, the light source controller counts the number of specific values included in one frame of the image data, and compares the counted number with a reference value defining a reference range to determine the gray level of the image data.

In example embodiments, the light source controller compares the data corresponding to the first line of the first frame of the image data with the data corresponding to the first line of the second frame adjacent to the first frame. The gray level of the video data is discriminated.

In example embodiments, the light source controller compares data corresponding to a first line of a first frame of the image data with data corresponding to a second line adjacent to the first line to compare the gray level of the image data. Determine.

The timing controller may include a latch for latching the image data in line units, a memory for storing line data provided in the latches in frame units and providing the stored image data to the liquid crystal display unit. Include. Here, the light source controller includes a counter, a comparator and a current controller. The counter counts a specific number included in the image data. The comparison unit compares the number counted by the counter with a reference range. The current controller controls the light source unit according to a comparison result by the comparison unit.

The timing controller may include a latch for latching the image data in line units, a memory for storing line data provided in the latches in frame units and providing the stored image data to the liquid crystal display unit. Include.

Here, the light source controller includes a first adder, a second adder, a comparator and a current controller. The first summation unit sums each of image data corresponding to a specific line input to the latch and image data corresponding to an adjacent line adjacent to the specific line output from the latch in units of bits. The second adding unit adds the sum data, which is added in bits by the first adding unit, in bits. The comparison unit compares the total value and the reference range by the second adding unit. The current controller controls the light source unit according to a comparison result by the comparison unit.

The timing controller may include a latch for latching the image data in line units, a memory for storing line data provided in the latches in frame units and providing the stored image data to the liquid crystal display unit. Include. Here, the light source controller includes a first resistor, a second resistor, a comparator and a current controller. The first register is the first register of the pre-stored (n + 1) th frame as image data corresponding to the first line of the (n + 2) th frame is provided from the memory, where 'n' is a natural number. Image data corresponding to a line is output, and image data corresponding to the first line of the (n + 2) th frame is sequentially stored. As the second register is provided with image data corresponding to the first line of the (n + 1) th frame from the first register, the second register outputs the image data corresponding to the first line of the (n) th frame stored in advance. The image data corresponding to the first line of the (n + 1) th frame is sequentially stored. The comparison unit compares the image data corresponding to the first line of the (n + 1) th frame provided from the first register with the image data corresponding to the first line of the (n) th frame provided from the second register. do. The current controller controls the light source unit according to a comparison result by the comparison unit.

According to such a backlight device and a liquid crystal display device having the same, a backlight device or the backlight device may be employed by providing light to the liquid crystal display panel with brightness adjusted using different driving currents according to the gray level of an input image. The power consumption of electronic products can be reduced.

Hereinafter, various embodiments of a backlight device and a liquid crystal display device having the same according to various aspects of the present invention will be described in detail with reference to the accompanying drawings, but the present invention is not limited to the following embodiments. Those skilled in the art may implement the present invention in various other forms without departing from the technical spirit of the present invention.

1 is an exploded perspective view illustrating a liquid crystal display according to an exemplary embodiment of the present invention.

Referring to FIG. 1, a liquid crystal display according to an exemplary embodiment of the present invention may include a light guide plate 30, a portion of the light guide plate 30, and a part of the flexible circuit board 10 disposed on the side of the flexible circuit board 10. It includes a storage container 40 for receiving, an optical sheet 50 disposed on the light guide plate 30, and a liquid crystal display panel 60 disposed on the optical sheet 50 to display an image. .

The flexible circuit board 10 includes a light emitting diode (LED) 20 in which at least one is arranged in a line on the substrate 11. The light emitting diode 20 is electrically connected to the signal lines 12. The light emitting diode 20 generates light using semiconductor characteristics.

The light guide plate 30 guides the light generated from the light emitting diodes 20 to the optical sheets 50. The optical sheets 50 improve the characteristics of the light incident from the light guide plate 30 to be emitted to the liquid crystal display panel 60.

The liquid crystal display panel 60 includes an array substrate 61, which is a TFT substrate in which thin film transistors (TFTs), which are switching elements, are formed in a matrix form, and an RGB pixel for realizing color while facing the array substrate 61. The liquid crystal layer 63 is interposed between the color filter substrate 62 formed in a thin film form and the array substrate 61 and the color filter substrate 62.

In addition, the liquid crystal display panel 60 further includes a driving chip 64 formed on the array substrate 61 to drive the liquid crystal display panel 60.

The liquid crystal display further includes a control substrate 70 connected to the liquid crystal display panel 60 to apply a driving signal to the liquid crystal display panel 60. The control substrate 70 is connected to the array substrate 61 of the liquid crystal display panel 60 through a control driving circuit film 80.

In addition, the control substrate 70 may apply a driving power for generating light from the light emitting diode 20 to the light emitting diode 20. Accordingly, by driving the solder portions 12 of the flexible circuit board 10 to the control substrate 70, driving power may be applied to the light emitting diodes 20.

In general, the type of image displayed on the display window of the mobile phone employing the liquid crystal display panel may include a video, a menu, and a button key. The luminance characteristics for each gray level according to the type of the image are as shown in FIG. 2 below. The button key includes a numeric image, a text image, and the like displayed on a display window as a user manipulates a keypad.

2 is a graph illustrating luminance characteristics for each gray level of an image according to an image type.

Referring to FIG. 2, the video has a relatively low gradation and luminance, the menu display image has a relatively intermediate gradation and luminance, and the button key display image has a relatively high gradation and luminance.

Therefore, the control substrate 70 according to the present invention, according to the gray level of the image data supplied to the liquid crystal display panel 60, as shown in Figure 3 below, to the light emitting diode 20 Is authorized.

3 is a graph illustrating the magnitude of a light source driving current applied according to the type of an image according to an embodiment of the present invention. In particular, FIG. 3 illustrates the magnitude of the light source driving current applied according to the type of the image when the liquid crystal display panel displaying the image includes the liquid crystal layer in the normally black mode. In the normally black mode liquid crystal display panel, the lower the voltage (or current) applied, the lower the luminance, and the higher the applied voltage (or current), the higher the luminance.

1 and 3, when the mobile phone displays a video, the control substrate 70 applies a relatively large driving current to the light emitting diode 20 and the mobile phone displays a menu image. The control substrate 70 applies a relatively intermediate driving current to the light emitting diode 20. In addition, when the mobile phone displays a button key image, the control substrate 70 applies a relatively small driving current to the light emitting diode 20.

Accordingly, since different driving currents are adjusted to the light emitting diodes according to the type of the image displayed on the display window of the mobile phone, power consumption of the mobile phone can be reduced.

4 is a graph illustrating the magnitude of a light source driving current applied according to the type of an image according to another exemplary embodiment of the present invention. In particular, FIG. 4 illustrates the magnitude of the light source driving current applied according to the type of the image when the liquid crystal display panel displaying the image includes the liquid crystal layer in the normally white mode. In the normally white mode liquid crystal display panel, the lower the voltage (or current) applied, the higher the luminance, and the higher the applied voltage (or current), the lower the luminance.

1 and 4, when the mobile phone displays a video, the control substrate 70 applies a relatively small driving current to the light emitting diode 20 and the mobile phone displays a menu image. The control substrate 70 applies a relatively intermediate driving current to the light emitting diode 20. In addition, when the mobile phone displays a button key image, the control substrate 70 applies a relatively high driving current to the light emitting diode 20.

Accordingly, since different driving currents adjusted according to the type of image displayed on the display window of the mobile phone are applied to the light emitting diode, power consumption of the mobile phone can be reduced.

5 is a block diagram illustrating a liquid crystal display according to an exemplary embodiment of the present invention.

Referring to FIG. 5, the liquid crystal display according to the exemplary embodiment may include a timing controller 100, a data driver 200, a gate driver 300, a liquid crystal display panel 400, a light source controller 500, and the like. The light source unit 600 is included. The timing controller 100, the data driver 200, and the gate driver 300 define an image signal processor that provides externally provided image data to the liquid crystal display panel 400. The light source controller 500 and the light source unit 600 define a backlight device that supplies light to a liquid crystal display panel displaying an image using liquid crystal.

As the first image data DATA1 and the first synchronization signal SYN1 are provided from the outside, the timing controller 100 receives the second image data DATA2 and the second synchronization signal SYN2 from the data driver 200. ) The timing controller 100 outputs a third synchronization signal SYN3 to the gate driver 300, and outputs the second image data DATA2 to the light source controller 500.

The first synchronization signal SYN1 includes a vertical synchronization signal Vsync, a horizontal synchronization signal Hsync, a main clock MCLK, and a data enable signal DE. The vertical synchronization signal Vsync indicates a time taken for displaying one frame. The horizontal sync signal Hsync represents a time taken for displaying one line. Accordingly, the horizontal synchronization signal Hsync includes pulses corresponding to the number of pixels included in one line. The data enable signal DE represents a time taken for data to be supplied to a pixel.

The second synchronization signal SYN2 includes a load signal LOAD, a horizontal start signal STH, and a polarity control signal REV for outputting the second image data DATA2. The polarity control signal REV controls the polarity of the second image data DATA2.

The third synchronization signal SYN3 includes a gate clock signal CPV or GCLK and a vertical start signal STV.

The data driver 200 outputs a data signal to the liquid crystal display panel 400 based on the second image data DATA2 and the second synchronization signal SYN2. The timing controller 100 and the data driver 200 that can be implemented on one chip are logically separated for convenience of description and are not separated in hardware.

The gate driver 300 outputs a gate signal to the liquid crystal display panel 400 based on the third synchronization signal SYN3.

The liquid crystal display panel 400 displays an image using a liquid crystal layer interposed between two substrates. Specifically, the liquid crystal display panel 400 is a switching formed in a region partitioned by a plurality of data lines DL, a plurality of gate lines GL, adjacent data lines and adjacent gate lines. An element TFT is included.

The data lines DL are arranged in the vertical direction. The data lines transmit a plurality of data signals to the switching element TFT. The gate lines GL are disposed in a horizontal direction. The gate lines sequentially transfer gate signals to the switching element TFT. The gate signals have a voltage level for turning on / off the switching element TFT.

The switching element (TFT) has a source electrode, a gate electrode, and a drain electrode. The source electrode is electrically connected to the data line DL to receive the data signal. The gate electrode is electrically connected to the gate line GL to receive the gate signal. The drain electrode is electrically connected to the liquid crystal capacitor Clc and the storage capacitor Cst.

The light source controller 500 receives the second image data DATA2 from the timing controller 100, determines an image type supplied to the liquid crystal display panel 400, and adjusts driving according to the gray level of the image data. The light source unit 600 is controlled to supply current.

In detail, the light source controller 500 controls the light source unit 600 so that a relatively small driving current is supplied when the image data is high gradation such as a button key display, and the image data is low gradation like a video display. In this case, the light source unit 600 is controlled to supply a relatively large driving current. The light source controller 500 controls the light source unit 600 to supply a relatively intermediate driving current when the image data has a halftone such as a menu display.

The light source unit 600 includes, for example, one or more red light emitting diodes (LEDs) emitting red light, one or more green LEDs emitting green light, and one or more blue LEDs emitting blue light. As another example, the light source unit 600 may include one or more lamps to supply light to the liquid crystal display panel 400 based on a driving current provided from the light source driver 500.

6 is a block diagram illustrating an example of the timing controller and the light source controller illustrated in FIG. 5.

5 and 6, the timing controller 100 includes a latch 110 and graphic memory 120.

The latch 110 latches image data provided from an external graphic controller in line units.

The graphic memory 120 stores line data provided by the latch 110 in frame units and provides the stored video data to the data driver 200.

The light source controller 500 includes a counter 510, a comparator 520, and a current controller 530. The light source controller 500 may count the number of specific values included in one frame of the image data, and determine the gray level of the image data by comparing the counted number with a reference value defining a reference range.

The counter 510 counts the number of specific values included in the image data. Typically, the image data includes R, G, and B image data defined by a plurality of bits.

For example, if the image data is 16 bits, the red image data corresponds to 5 bits, the green image data corresponds to 6 bits, and the blue image data corresponds to 5 bits. The red image data corresponds to the most significant bit (MSB) side, and the blue image data corresponds to the least significant bit (LSB) side, so that a total of 16 bits define one image data.

Accordingly, the counter 510 counts the number of '0' or '1' included in the image data. For example, '0' corresponds to black gradation and '1' corresponds to white gradation. In this embodiment, the counter 510 counts the number of '1's.

The comparison unit 520 compares the number counted by the counter 510 with a reference value (Ref.) That defines a reference range.

The current controller 530 controls the driving of the light source unit 600 according to the comparison result by the comparator 520.

For example, when the counted number is larger than the reference range, the current controller 530 provides a relatively small driving current to the light source unit 600. Accordingly, the light source unit 600 provides relatively dark light to the liquid crystal display panel 400. In this case, a high gradation image such as a button key display is displayed on the liquid crystal display panel 400.

The current controller 530 provides a normal driving current to the light source unit 600 when the counted number is within the reference range. Accordingly, the light source unit 600 provides normal light to the liquid crystal display panel 400. In this case, an image of a halftone such as a menu display is displayed on the liquid crystal display panel 400.

When the counted number is smaller than the reference range, the current control unit 530 provides a relatively large driving current to the light source unit 600. Accordingly, the light source unit 600 provides relatively bright light to the liquid crystal display panel 400. In this case, a low gray level image such as a video display is displayed on the liquid crystal display panel 400.

As described above, by comparing the gray level change of the image data corresponding to the two to three frames through the comparison unit 520 provided in the light source control unit 500 by adjusting the current consumption of the light source unit 500 In addition, the power consumption of a mobile communication terminal such as a mobile phone can be reduced.

In operation, all image data input to the timing controller 100 are compared by the comparator 520 for 2 to 3 frames. As a result of the comparison by the comparison unit 520, when the amount of data to be changed is small, the result of counting the number of '1' of one frame data by the counter 510 is transmitted to the current controller 530. The counter 510 is designed to count, for example, the number of '1's included in the input image data.

Thereafter, the current controller 530 determines the current consumption of the light source unit 600 according to the result of the counter 510.

For example, if a liquid crystal display panel having a resolution of 128 x 160 has a 16-bit interface, image data input during one frame is 40,960 bytes. The image data corresponding to the 16-bit interface includes 5 bits of red image data, 6 bits of green image data, and 5 bits of blue image data.

The counter 510 counts the number of '1's included in a total of 40,960 bytes (or 327,680 bits) of image data input during one frame.

As the number of '1's increases (that is, the number of' 0's decreases), the screen corresponding to the image data is closer to the white screen. Therefore, the current control unit 530 reduces the power consumption by reducing the driving current applied to the light source unit 600.

Meanwhile, as the number of '1's decreases (ie, the number of' 0's increases), the screen corresponding to the image data is closer to the black screen. Therefore, the current control unit 530 increases the display brightness by increasing the driving current applied to the light source unit 600, thereby improving visibility.

For example, when the number of '1' counted for one frame is 80,000 or less, the current controller controls the light source unit 600 to apply a driving current of approximately 20 mA.

On the other hand, if the number of '1' counted during one frame is 80,000 to 240,000, the current controller controls the light source unit 600 to apply a driving current of approximately 18mA.

On the other hand, if the number of '1' counted for one frame is 240,000 or more, the current controller controls the light source unit 600 to apply a driving current of approximately 16mA.

The power consumption of the backlight device including four LEDs will be described in Table 1 below. Here, the driving voltage of each LED is 4.5V. The backlight device according to the comparative example is driven using a fixed driving current regardless of the characteristics of the screen. On the other hand, the backlight device according to the present embodiment is driven using a driving current that varies according to the characteristics of the screen.

[Table 1]

Characteristics of the screen According to the comparative example
Power Consumption of BLU According to the embodiment
Power Consumption of BLU Reduced power consumption Dark screen 4.5V × 20mA * 4 = 360mW 4.5V × 20Ma * 4 = 360mW 0 mW Normal screen 4.5V × 20mA * 4 = 360mW 4.5V × 18Ma * 4 = 324mW 36mW Bright screen 4.5V × 20mA * 4 = 360mW 4.5V × 16Ma * 4 = 288mW 72 mW

As shown in Table 1, the backlight device according to the comparative example is provided with a fixed driving current of approximately 20 mA regardless of a dark screen such as a video, a normal screen such as a menu, and a bright screen such as a button key. Accordingly, the backlight device according to the comparative example has a power consumption of approximately 360 mW corresponding to each of the dark screen, the normal screen, and the bright screen.

However, the backlight device according to the present embodiment is provided with driving currents of about 20 mA, about 18 mA, and about 16 mA corresponding to each of the dark screen, the normal screen, and the bright screen. Accordingly, in the backlight device according to the present embodiment, power consumption is about 360 mW, about 324 mW, and about 288 mW, respectively, corresponding to the dark screen, the normal screen, and the bright screen.

Considering the power consumption of the backlight device according to the present embodiment and the backlight device according to the comparative example, the power consumption reduced corresponding to a substantially dark screen is 0 mW. However, the power consumption reduced in response to the normal screen is about 36mW, and the power consumption reduced in response to the bright screen is about 72mW.

Therefore, according to the present invention, the power consumption of approximately 72mW is reduced when the mobile communication terminal is driven, such as a mobile phone in which a relatively bright screen is mainly used. Accordingly, the battery life of the mobile communication terminal is increased.

FIG. 7 is a block diagram illustrating another example of the timing controller and the light source controller illustrated in FIG. 5.

5 and 7, the timing controller 100 includes a latch 110 and a graphics memory 120. The timing controller 100 is connected to the timing controller 100 as illustrated in FIG. 6. Since they are the same, the same reference numerals are given, and detailed description thereof will be omitted.

 The light source controller 500 includes a first adder 540, a second adder 550, a comparator 560, and a current controller 570. The light source controller 500 determines the gray level of the image data by comparing the data corresponding to the first line of the first frame of the image data with the data corresponding to the second line adjacent to the first line. .

The first adder 540 sums first image data input to the latch 110 and second image data output from the latch 110 in units of bits. The first image data is image data corresponding to a first line of a first frame, and the second image data is image data corresponding to a second line subsequent to the first line.

For example, when the first summer 540 includes a first summer, a second summer, a third summer, and a fourth summer, the first summer is equal to the n-th MSB of the first image data. The n-th MSB of the second image data is added, and the sum of the n-th MSB summed value is provided to the second adder 550.

The second summer adds the (n-1) th MSB of the first image data and the (n-1) th MSB of the second image data, and adds the sum of the (n-1) th MSB summed values. The adder 550 is provided.

The third summer adds the (n-2) th MSB of the first image data and the (n-2) th MSB of the second image data, and adds the sum of the (n-2) th MSB summed values. The adder 550 is provided.

The fourth summer adds the (n-3) th MSB of the first image data and the (n-3) th MSB of the second image data, and adds the sum of the (n-3) th MSB summed values to the second image data. The adder 550 is provided.

The second adder 550 adds the plurality of sum data added in the bit unit by the first adder 540 in the bit unit.

For example, the second adder 550 may add the nth MSB summation value, the (n-1) th summation value, the (n-2) th summator, and (n-3) of the first and second image data. ) Summed values are added, and the summed result is provided to the comparison unit 560.

The comparison unit 560 compares the result value provided by the second adding unit 550 with a reference range, and provides the comparison value according to the comparison to the current control unit 570.

For example, if the result value is larger than the reference range, the comparison unit 560 provides the current control unit 570 with a first comparison value corresponding to a bright screen. If the result value is within the reference range, the comparison unit 560 provides the current control unit 570 with a second comparison value corresponding to a normal screen. If the result value is smaller than the reference range, the comparison unit 560 provides the current control unit 570 with a third comparison value corresponding to the dark screen.

The current control unit 570 controls the driving of the light source unit 600 according to the comparison result by the comparison unit 560.

For example, when the first comparison value is provided to the current controller 570, the current controller 570 provides a relatively small driving current to the light source unit 600. Accordingly, the light source unit 600 provides relatively dark light to the liquid crystal display panel 400. In this case, a high gradation image such as a button key display is displayed on the liquid crystal display panel 400.

When the second comparison value is provided to the current controller 570, the current controller 570 provides a normal driving current to the light source unit 600. Accordingly, the light source unit 600 provides normal light to the liquid crystal display panel 400. In this case, an image of a halftone such as a menu display is displayed on the liquid crystal display panel 400.

When the third comparison value is provided to the current controller 570, the current controller 570 provides a relatively large driving current to the light source unit 600. Accordingly, the light source unit 600 provides relatively bright light to the liquid crystal display panel 400. In this case, a low gray level image such as a video display is displayed on the liquid crystal display panel 400.

FIG. 8 is a block diagram illustrating another example of the timing controller and the light source controller illustrated in FIG. 5.

5 and 8, the timing controller 100 includes a latch 110 and a graphics memory 120. Since the timing controller 100 is the same as the timing controller 100 illustrated in FIG. 6, the timing controller 100 is given the same reference numeral, and detailed description thereof will be omitted.

The light source controller 600 includes a first register 610, a second register 620, a comparator 630, and a current controller 6400. The light source controller 600 corresponds to data corresponding to the first line of the (n) th frame of the image data and corresponding to the first line of the (n + 1) th frame adjacent to the (n) th frame. The gray level of the image data is determined by comparing the data with each other.

Specifically, the first register 610 is provided with the image data corresponding to the first line of the (n + 2) th frame in the graphics memory 120, the image data of the (n + 1) th frame stored (Where n is a natural number) is sequentially provided to the second register 620 and the comparator 630, and stores image data corresponding to the first line of the (n + 2) th frame.

As the second register 620 is provided with image data corresponding to the first line of the (n + 1) th frame in the first register 610, the second register 620 corresponds to the first line of the stored (n) th frame. Image data is provided to the comparator 630, and image data corresponding to the first line of the (n + 1) th frame is stored.

The comparator 630 may include image data corresponding to the first line of the (n) th frame provided by the second register 620 and the (n + 1) th frame provided by the first register 610. The image data corresponding to the first line is compared. For example, the comparison unit 630 may determine bits of the image data corresponding to the first line of the (n) th frame and bits of the image data corresponding to the first line of the (n + 1) th frame. Compare with each other to calculate the number of bits that change. Subsequently, the comparison unit 630 compares the calculated number of bits with a reference value Ref. Corresponding to the reference range, and then provides a comparison value according to the comparison to the current controller 640.

For example, when the result value is greater than the reference range, the comparison unit 630 provides the current control unit 640 with a first comparison value corresponding to a bright screen. If the result value is within the reference range, the comparison unit 630 provides the current control unit 640 with a second comparison value corresponding to a normal screen. If the result value is smaller than the reference range, the comparison unit 630 provides the current control unit 640 with a third comparison value corresponding to the dark screen.

The current control unit 640 controls the light source unit 600 according to the comparison result by the comparison unit 630.

For example, when the first comparison value is provided to the current controller 640, the current controller 640 provides a relatively small driving current to the light source unit 600. Accordingly, the light source unit 600 provides relatively dark light to the liquid crystal display panel 400. At this time, the liquid crystal display panel 400 displays a high gradation image such as numeric key display.

When the second comparison value is provided to the current controller 640, the current controller 640 provides a normal driving current to the light source unit 600. Accordingly, the light source unit 600 provides normal light to the liquid crystal display panel 400. In this case, an image of a gray scale such as a menu display is displayed on the liquid crystal display panel 400.

When the third comparison value is provided to the current controller 640, the current controller 640 provides a relatively large driving current to the light source unit 600. Accordingly, the light source unit 600 provides relatively bright light to the liquid crystal display panel 400. In this case, a low gray level image such as a video display is displayed on the liquid crystal display panel 400.

As described above, according to the present invention, the power consumption of the mobile communication terminal such as a mobile phone can be reduced by adjusting the current consumption of the light source unit emitting light in consideration of the change in the gray level of the image data.

That is, the backlight device according to the present invention employs a backlight device or the backlight device by adjusting the brightness of light using different driving currents according to the gray level of an input image and providing the brightness-controlled light to the liquid crystal display panel. Can reduce the power consumption of electronic products such as mobile phones.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the present invention as defined by the following claims. You will understand.

Claims (31)

delete delete delete delete delete delete delete delete A liquid crystal display for displaying an image using liquid crystal; A timing controller configured to provide externally supplied image data to the liquid crystal display; A light source unit providing light to the liquid crystal display unit; And And a light source controller configured to control the light source unit to supply a first driving current when the image data is high gradation, and to control the light source unit to supply a second driving current when the image data is low gradation. The light source control unit, Counting the number of specific values included in one frame of the image data, comparing the counted number with a reference value defining a reference range, and determining a gray level of the image data; And the specific value is a bit value included in the image data. The method of claim 9, wherein the light source unit, Liquid crystal display comprising a light emitting diode. The liquid crystal display device of claim 9, wherein the liquid crystal display includes a liquid crystal layer in a normally black mode. And the first driving current is smaller than the second driving current. The method of claim 11, wherein the light source control unit, And controlling the light source unit to supply a third driving current when the image data is a halftone. The liquid crystal display of claim 12, wherein the third driving current is larger than the first driving current and smaller than the second driving current. The liquid crystal display of claim 9, wherein the liquid crystal display comprises a liquid crystal layer in a normally white mode. And the first driving current is greater than the second driving current. The method of claim 14, wherein the light source control unit, And controlling the light source unit to supply a third driving current when the image data is a halftone. The liquid crystal display of claim 15, wherein the third driving current is smaller than the first driving current and larger than the second driving current. 10. The method of claim 9, wherein the image data includes a relatively high gradation image and a relatively low gradation image, The high gradation image corresponds to a button key image displayed on the liquid crystal display, And the low gradation image corresponds to a video displayed on the liquid crystal display. 18. The method of claim 17, wherein the image data comprises a half-tone image between the high and low grayscale image, And the halftone image corresponds to a menu displayed on the liquid crystal display. The liquid crystal display of claim 9, wherein the timing controller and the light source controller are implemented in the same hardware. delete A liquid crystal display for displaying an image using liquid crystal; A timing controller configured to provide externally supplied image data to the liquid crystal display; A light source unit providing light to the liquid crystal display unit; And And a light source controller configured to control the light source unit to supply a first driving current when the image data is high gradation, and to control the light source unit to supply a second driving current when the image data is low gradation. The light source control unit, Data corresponding to a first line of a first frame of the image data; And a gray level of the image data is determined by comparing data corresponding to a second line adjacent to the first line with each other. A liquid crystal display for displaying an image using liquid crystal; A timing controller configured to provide externally supplied image data to the liquid crystal display; A light source unit providing light to the liquid crystal display unit; And And a light source controller configured to control the light source unit to supply a first driving current when the image data is high gradation, and to control the light source unit to supply a second driving current when the image data is low gradation. The light source control unit, Data corresponding to a first line of a first frame of the image data; And a gray level of the image data is determined by comparing data corresponding to a first line of a second frame adjacent to the first frame with each other. The method of claim 9, wherein the timing controller A latch for latching the image data in line units; And A memory for storing line data provided by the latch in frame units and providing the stored video data to the liquid crystal display; The light source control unit, A counter for counting a specific number included in the image data; A comparison unit comparing the number counted by the counter with a reference range; And And a current controller for controlling the light source unit according to a comparison result by the comparison unit. The method of claim 23, wherein the specific number is '1', The current control unit, When the number of '1' is larger than the reference range, the first driving current is provided to the light source unit, And providing the second driving current to the light source unit when the number of '1' is smaller than the reference range. The method of claim 24, wherein the current control unit, And when the number of '1' is in the reference range, providing a third driving current existing between the first driving current and the second driving current to the light source unit. The method of claim 23, wherein the specific number is '0'. The current control unit, When the number of '0' is larger than the reference range, the second driving current is provided to the light source unit, And when the number of '0' is smaller than the reference range, provide the first driving current to the light source unit. The method of claim 26, wherein the current control unit, And when the number of '0' is within the reference range, providing a third driving current existing between the first driving current and the second driving current to the light source unit. The method of claim 21, wherein the timing controller, A latch for latching the image data in line units; And A memory for storing line data provided by the latch in frame units and providing the stored video data to the liquid crystal display; The light source control unit, A first adder configured to add image data corresponding to a specific line input to the latch and image data corresponding to an adjacent line adjacent to the specific line output from the latch in bit units; A second adder configured to add the sum data, which is added in bits by the first adder, in bits; A comparison unit for comparing the total value by the second adding unit with a reference range; And And a current controller for controlling the light source unit according to a comparison result by the comparison unit. The method of claim 28, wherein the current control unit, When the sum is greater than the reference range, the first driving current is provided to the light source unit. And the second driving current is provided to the light source unit when the sum value is smaller than the reference range. The method of claim 29, wherein the current control unit, And when the sum is within the reference range, a third driving current existing between the first driving current and the second driving current is provided to the light source unit. The method of claim 22, wherein the timing controller, A latch for latching the image data in line units; And A memory for storing line data provided by the latch in frame units and providing the stored video data to the liquid crystal display; The light source control unit, As image data corresponding to the first line of the (n + 2) th frame is provided from the memory (where 'n' is a natural number), the image corresponding to the first line of the previously stored (n + 1) th frame is provided. A first register configured to output data and sequentially store image data corresponding to the first line of the (n + 2) th frame; As image data corresponding to the first line of the (n + 1) th frame is provided from the first register, the image data corresponding to the first line of the (n) th frame stored in advance is output, and the (n + 1) a second register sequentially storing image data corresponding to the first line of the first frame; A comparator for comparing image data corresponding to the first line of the (n + 1) th frame provided from the first register with image data corresponding to the first line of the (n) th frame provided from the second register ; And And a current controller for controlling the light source unit according to a comparison result by the comparison unit.

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