KR101482069B1 - Local dimming method of light source, light-source apparatus performing for the method and display apparatus having the light-source apparatus - Google Patents

Abstract

In a light source local dimming method, a light source device for performing the same, and a display device having the light source device, a light source local dimming method for driving a light source including a plurality of light emitting blocks for each light emitting block, The luminance of the first light emitting region is changed according to the size of the first light emitting region corresponding to the first light emitting region. The brightness of the first light emitting region is increased and driven as the size of the first light emitting region is smaller and the brightness of the first light emitting region is decreased as the size of the first light emitting region is larger. Accordingly, it is possible to prevent blindness and improve contrast ratio.

Contrast ratio, eyeblinking phenomenon, boosting driving method, local dimming driving

Description

TECHNICAL FIELD [0001] The present invention relates to a light source local dimming method, a light source device for performing the same, and a display device having the light source device. [0002]

The present invention relates to a light source local dimming method, a light source device for performing the same, and a display device having the light source device. More particularly, the present invention relates to a light source local dimming method for individually driving a plurality of light emitting blocks, And a display device including the light source device.

In general, a liquid crystal display device includes a liquid crystal display panel displaying an image using light transmittance of a liquid crystal, and a backlight assembly disposed under the liquid crystal display panel and providing light to the liquid crystal display panel.

The liquid crystal display panel comprising: an array substrate having pixel electrodes and thin film transistors electrically connected to the pixel electrodes; a color filter substrate having color filters and a common electrode; and a liquid crystal layer interposed between the array substrate and the color filter substrate .

The liquid crystal layer is changed in arrangement by the electric field formed between the pixel electrodes and the common electrode, thereby changing the transmittance of light passing through the liquid crystal layer. If the transmittance of the light is maximized, the liquid crystal display panel can realize a white image with high brightness, whereas if the transmittance of the light is minimized, the liquid crystal display panel can realize a black image with low brightness .

However, such a liquid crystal display device is disadvantageous in that it is more glare than other display devices such as CRT (Cathod Ray Tube) and PDP (Plasma Display Panel). The liquid crystal display device does not emit light directly but uses external light to express an image. Therefore, luminance distribution is different from that of CRT or PDP. These other luminance distribution characteristics cause users to feel fatigue in the eyes.

In recent years, a local dimming method has been developed in which a light source is divided into a plurality of light-emitting blocks and the brightness is controlled for each light-emitting block in order to prevent a phenomenon in which the contrast ratio of an image is reduced and power consumption is minimized. Through the local dimming method, there is a movement to solve glare which is a problem of the conventional liquid crystal display device. The local dimming method has a characteristic that luminance can be controlled for each light emitting block, and using such a characteristic can realize the same effect as driving characteristics of CRT or PDP.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for local dimming of a light source for improving display quality.

It is another object of the present invention to provide a light source device particularly suited for performing the light source local dimming method.

It is still another object of the present invention to provide a display device provided with the light source device.

According to an exemplary embodiment of the present invention, a light source local dimming method for driving a light source including a plurality of light-emitting blocks for each light-emitting block includes a first light emission corresponding to a display region in which a maximum- The luminance of the first light emitting region is changed according to the size of the region. As the size of the first light emitting region is smaller, the brightness of the first light emitting region is increased and driven. As the size of the first light emitting region is increased, the brightness of the first light emitting region is decreased and driven.

Also, if the representative gray scale value of the image is equal to or greater than a preset reference value, the light emitting block corresponding to the representative gray scale value is determined as the first light emitting area. And determines the first luminance level of the first light emitting region according to the size of the first light emitting region. And drives the first light emitting region according to the first luminance level. The first brightness level is determined to be larger as the size of the first light emitting region is smaller and the first brightness level of the first light emitting region is determined to be smaller as the size of the first light emitting region is larger. When the size of the first light emitting region is the minimum, the first luminance level becomes the maximum.

According to another aspect of the present invention, there is provided a light source device including a light source module and a local dimming driver. The light source module provides light to a display panel divided into a plurality of display blocks, and includes a plurality of light-emitting blocks corresponding to the display blocks. The local dimming driver changes the brightness of the light emitting block included in the first light emitting area according to the size of the first light emitting area of the light source module corresponding to the area of the display panel in which the image of the maximum brightness is displayed.

The local dimming driver includes a representative value calculating unit, an area determining unit, a brightness determining unit, and a light emitting driver. The representative value calculation unit calculates the representative tone value of the corresponding image for each display block. The region determining unit determines the light emitting block corresponding to the representative gray level value as the first light emitting region when the representative gray scale value is equal to or greater than a reference value. Wherein the brightness determining unit determines the first brightness level of the first light emitting area, determines the first brightness level to be large if the size of the first light emitting area is small, The luminance level is determined to be small. The light emitting driver drives the light emitting block included in the first light emitting region according to the first brightness level.

Preferably, the light-emitting blocks are divided into a plurality of driving blocks having a matrix structure of IxJ (I, J is a natural number), and each driving block has a plurality of (i, j) Lt; / RTI > The light emitting driver includes a driving chip and a switching unit. The driving chip includes the ix j output channels, and outputs ix j driving signals to the output channels. The switching unit includes the IxJ switching elements connected in parallel to each output channel, and the IxJ switching elements deliver the driving signal applied to the output channel to the IxJ driving blocks. The IxJ switching devices time-divide the driving signal applied to the output channel and deliver the driving signal to the IxJ driving blocks. The frame includes IxJ periods, and one switching element of the IxJ switching elements is turned on to drive one light-emitting block included in one driving block during one section. The light emitting driver increases the turn-on time of the switching element connected to the light emitting block included in the first light emitting area by a maximum of IXJ times to increase the brightness of the light emitting block.

According to another aspect of the present invention, there is provided a display apparatus including a display panel, a light source module, and a local dimming driver. The display panel displays an image and is divided into a plurality of display blocks. The light source module provides light to a display panel divided into a plurality of display blocks, and includes a plurality of light-emitting blocks corresponding to the display blocks. The local dimming driver changes the brightness of the light emitting block included in the first light emitting area according to the size of the first light emitting area of the light source module corresponding to the area of the display panel in which the image of the maximum brightness is displayed.

According to the present invention, by changing the brightness of the light emitting blocks included in the light emitting area according to the size of the light emitting area having the maximum brightness, it is possible to prevent blindness and improve the contrast ratio.

Hereinafter, preferred embodiments of the present invention will be described in more detail with reference to the drawings. The present invention is capable of various modifications and various forms, and specific embodiments are illustrated in the drawings and described in detail in the text. It should be understood, however, that the invention is not intended to be limited to the particular forms disclosed, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. Like reference numerals are used for like elements in describing each drawing. In the accompanying drawings, the dimensions of the structures are enlarged from the actual size in order to clarify the present invention. The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component. The singular expressions include plural expressions unless the context clearly dictates otherwise.

In this application, the terms "comprises", "having", and the like are used to specify that a feature, a number, a step, an operation, an element, a part or a combination thereof is described in the specification, But do not preclude the presence or addition of one or more other features, integers, steps, operations, components, parts, or combinations thereof. Also, where a section such as a layer, a film, an area, a plate, or the like is referred to as being "on" another section, it includes not only the case where it is "directly on" another part but also the case where there is another part in between. On the contrary, where a section such as a layer, a film, an area, a plate, etc. is referred to as being "under" another section, this includes not only the case where the section is "directly underneath"

1 is a block diagram of a display device according to an embodiment of the present invention.

Referring to FIG. 1, a display device includes a display panel 100, a timing controller 110, a panel driver 130, a light source module 200, and a local dimming driver 270.

The display panel 100 includes a plurality of pixels for displaying an image, for example, the pixels are M x N (where M and N are natural numbers). Each pixel P includes a switching element TR connected to the gate wiring GL and the data wiring DL, a liquid crystal capacitor CLC connected to the switching element TR and a storage capacitor CST. The display panel 100 includes a plurality of display blocks D, for example, the display blocks are divided. The display blocks D are m x n (m <M, n <N are natural numbers).

The timing controller 110 receives the control signal 101 and the video signal 102 from the outside. And generates a timing control signal 110a for controlling the driving timing of the display panel 100 using the received control signal. The timing control signal includes a clock signal, a horizontal start signal, and a vertical start signal. And receives the control signal and the video signal from the local dimming driver 270, for example.

The panel driver 130 drives the display panel 100 using the timing control signal 110a and the video signal 110b provided from the timing controller 110. [ For example, the panel driver 130 may include a gate driver for generating a gate signal to be supplied to the gate wiring GL using the timing control signal, and a gate driver for applying the timing control signal and the video signal to the data line DL to generate a data signal.

The light source module 200 includes a printed circuit board on which a plurality of light emitting diodes are mounted. The light emitting diodes may include red, green, blue, and white light emitting diodes. Alternatively, the light emitting diodes may be white light emitting diodes. The light source module 200 includes m × n light-emitting blocks B corresponding to the m × n display blocks D. The light-emitting blocks B are disposed at positions corresponding to the display blocks D, respectively. Each light-emitting block B includes a plurality of light-emitting diodes.

The local dimming driver 270 includes a representative value calculating unit 210, an area determining unit 220, a brightness determining unit 230, and a light emitting driver 240.

The representative value calculating unit 210 calculates a representative gray-level value corresponding to each display block D using the video signal 102 received from the outside. The representative tone value may be an average tone value, a maximum tone value, or the like of the image signal displayed on the display block. The representative tone value may be determined by various methods.

The region determining unit 220 compares the representative gray-level value with a predetermined reference value, and determines the corresponding light-emitting block as the first light-emitting region having the maximum brightness if the representative gray-level value is equal to or greater than the reference value, Is smaller than the reference value, the light-emitting block is determined as the second light-emitting region having the normal luminance. For example, the reference value is the white gradation value, the maximum luminance is the luminance of the white gradation image, and the general luminance is the luminance of the intermediate gradation image.

The brightness determining unit 230 determines a first brightness level corresponding to the first light emitting region and determines a second brightness level corresponding to the second light emitting region. The first brightness level is determined according to the size of the first light emitting area with respect to the total size of the mxn light emitting blocks B. For example, if the size of the first light emitting region is small, the first luminance level becomes large, and if the size of the first light emitting region is large, the first luminance level becomes large. If the size of the first light emitting region is the smallest, the first luminance level becomes the maximum. The second brightness level is determined using a gamma curve and a representative gray value of the light emitting blocks B of the second light emitting area. The gamma curve includes a luminance distribution according to the representative gray-scale value.

The light emission driving part 240 outputs a driving signal for controlling the light emission of the light emitting blocks corresponding to the first light emitting area by using the first luminance level and outputs the driving signal to the second light emitting area And outputs a drive signal for controlling the light emission of the corresponding light emitting blocks.

Accordingly, if the size of the first light emitting region is small, the light emitting blocks corresponding to the first light emitting region generate light of high luminance, and if the size of the first light emitting region is large, The light-emitting blocks corresponding to the light-emitting region generate light of low luminance.

Hereinafter, the driving principle of the brightness determining unit will be described. That is, it is explained that the brightness level is determined in accordance with the sizes of the first light emitting region and the second light emitting region and the representative tone value.

2 is a graph showing the relationship between the size of the light emitting region and the luminance applied to the display device of FIG.

Referring to FIGS. 1 and 2, first, a case where the entire region of the light source module 200 is determined as the second light emitting region will be described. The second light emitting region is a case in which the representative gray scale value of the light emitting block is smaller than the reference value.

In this case, the brightness determining unit 230 determines the second brightness level using the representative gray-scale values of the light-emitting blocks B and a gamma curve. For example, the second luminance level can be determined using the luminance to which the gamma curve is applied to the maximum gradation value among the representative gradation values of the light-emitting blocks (B). As shown in FIG. 2, the brightness determining unit 230 determines that the second brightness level gradually increases as the representative tone value of the second light emitting region gradually increases.

Second, the case where the light source module 200 is determined as the first light emitting region and the second light emitting region will be described. The first light emitting region is a case in which the representative gray scale value of the light emitting block is equal to or greater than the reference value and the representative gray scale value of the light emitting block in the second light emitting region is smaller than the reference value.

In this case, the brightness determining unit 230 controls the brightness level of the first light emitting region according to the size of the first light emitting region. The first brightness level is increased as the size of the first light emitting region is smaller and the first brightness level is decreased as the size of the first light emitting region is larger. As described above, the driving method for rapidly increasing the luminance as the size of the first light emitting region is smaller is referred to as a boosting driving method. In general, the full white luminance is about 500 nits, and the luminance of the first light emitting region rises to about 1000 nits by the boosting driving method. At this time, the total power consumption for driving the light source module 200 is always constant regardless of the size of the first light emitting region.

The brightness determining unit 230 determines the second brightness level of the second light emitting region using the representative tone values of the light emitting blocks included in the second light emitting region and the gamma curve.

When the entire area of the light source module 200 is determined to be the first light emitting area, the brightness determining unit 230 determines the first brightness level of the first light emitting area as an intermediate brightness level (CRT) Is set to be larger than the average luminance of the PDP). As shown in FIG. 2, if the total luminance range is 0 to 160, the first luminance level can be determined to be about 60. [ In general, the full white luminance is about 500 nits, and the luminance of the first light emitting region is driven as low as about 300 nits.

The liquid crystal display according to the embodiment can increase the average luminance (in the third case) with respect to the CRT or PDP, increase the luminance of the first light emitting region exponentially as the size of the first light emitting region decreases, And the contrast ratio (CR) of the PDP can be improved (in the second case).

FIG. 3A is a plan view of an image displayed on the display panel of FIG. 1; FIG. 3B is a plan view of the light source module corresponding to the image of FIG. 3A.

Referring to FIG. 3A, the display panel 100 is divided into a plurality of display blocks D. FIG. The representative gradation value of the image displayed in each display block D is divided into the first display region 410 and the second display region 450 by comparing the representative gradation value with the reference value. The first display area 410 includes display blocks having the representative tone value equal to or greater than a reference value, and the second display area 450 includes display blocks having the representative tone value smaller than the reference value. The representative tone value may be determined by various methods such as an average tone value or a maximum tone value of the image displayed on the display block.

Referring to FIG. 3B, the light source module 200 is divided into a plurality of light-emitting blocks B. The light emitting blocks B are divided into a first light emitting region 510 and a second light emitting region 550 corresponding to the first display region 410 and the second display region 450.

The first light emission region 550 has a first brightness level determined according to its size. The first brightness level is determined according to the size of the first light emitting region 510. For example, as described with reference to FIG. 2, since the size of the first light emitting region 510 is about 15% of the entire region, the first luminance level is determined to be about 118. And drives the first light emitting region 510 in a boosting driving manner.

The second luminance level of the second light emitting region 550 is determined according to the representative gray level of the corresponding display blocks and the gamma curve. The gamma curve can be set by various variables. The second brightness level may be determined for each light emitting block included in the second light emitting area 550. In addition, the luminance level of the light-emitting block can be compensated by various methods in consideration of the luminance level of adjacent light-emitting blocks. For example, a compensation matrix having a size of 3 × 3, 16 × 16, or P × Q (P, Q is a natural number) may be applied to compensate the luminance level of the light emitting block. For example, as described in FIG. 2, the second luminance level is determined to be about 10 to 30.

As a result, the first light emitting region 510 is driven at a high luminance by the boosting driving method, and the second light emitting region 550 is driven at a normal luminance, thereby improving the contrast ratio. Further, by concentrating the power consumption of the second light emitting area 550 in the first light emitting area 510, the power consumption for driving the light source module 200 can be reduced.

4A is a plan view of an image according to another example displayed on the display panel of FIG. 4B is a plan view of the light source module corresponding to the image of FIG. 4A.

Referring to FIG. 4A, the display panel 100 is divided into a plurality of display blocks D. FIG. The display panel 100 includes only a first display area 610. That is, the representative tone values of the display blocks D are all larger than the reference value.

Referring to FIG. 4B, the light source module 200 is divided into a plurality of light-emitting blocks B. The first light emitting region 710 includes all the light emitting blocks B corresponding to the first display region 610. The first light emitting region 710 has a first brightness level determined according to the size thereof. For example, as illustrated in FIG. 2, the first light emitting region 710 corresponds to the entire region, so that the size of the first light emitting region 710 is 100%. Accordingly, the first luminance level of the first light emitting region 710 is determined to be about 58. [

2, the first luminance level has a minimum value within a range of the luminance level of the first emission region, about 58 to about 160, when the size of the first emission region is a maximum value.

In a typical liquid crystal display device, when full white gradation is displayed on a display panel, the luminance of light generated from the light source module is also driven with the maximum luminance, thereby causing glare. However, in the present embodiment, when full white gradation is displayed on the display panel, the brightness of light generated from the light source module is driven to be lower than the maximum luminance, thereby preventing the glare.

Also, as the first brightness level of the first light emitting region 710 decreases, the power consumption for driving the light source module 200 can be reduced.

5 is a circuit diagram of the light emitting driver shown in FIG.

1 and 5, the light emission driving unit 240 includes a driving chip 241 and a plurality of switching units 242, ..., and 249, and drives the light source module 200.

The light source module 200 includes a plurality of light emitting blocks having a matrix structure of ix j (i, j is a natural number). The plurality of light emitting blocks are divided into a plurality of driving blocks having a matrix structure of IxJ (I, J is a natural number).

For example, as shown in FIG. 5, the light source module 200 includes 8 × 8 light-emitting blocks B, and the light-emitting blocks B include eight driving blocks BD1,. .., BD8). The drive blocks BD1, ..., BD8 have, for example, a 4 × 2 matrix structure.

For example, the first driving block BD1 includes first through eighth light emitting blocks 1a through 1h, the second driving block BD2 includes first through eighth light emitting blocks 2a through 2h, The third driving block BD3 includes first through eighth light emitting blocks 3a through 3h and the fourth driving block BD4 includes first through eighth light emitting blocks 4a through 4h. The fifth driving block BD5 includes first through eighth light emitting blocks 5a through 5h and the sixth driving block BD6 includes first through eighth light emitting blocks 6a through 6h, The seventh driving block BD7 includes first through eighth light emitting blocks 7a through 7h and the eighth driving block BD8 includes first through eighth light emitting blocks 8a through 8h. .

The driving chip 241 includes the ix j output channels. Preferably, the number of output channels of the driving chip 241 corresponds to the number of light emitting blocks included in each driving block. For example, the driving chip 241 includes eight output channels 241a, 241b, ..., 241h corresponding to the number of eight light-emitting blocks included in each driving block.

The plurality of switching units 242, 243, ..., and 249 are connected to the output channels 241a, 241b, ..., and 241h, respectively. Each switching unit 242 includes the IxJ switching elements connected in parallel to each output channel 241a and includes eight switching elements S11, S12, ..., S18, for example. do.

A driving signal applied from each output channel is input to the input terminal of each of the switching elements S11, S12, ..., S18, a control signal is input to the control terminal, And is electrically connected to the block (B). The switching elements S11, S12, ..., S18 output the driving signals to the electrically-connected light-emitting blocks in response to the control signals input to the respective control ends. The control signal is provided from the driving chip 241.

The driving chip 241 is connected to the first to eighth driving blocks BD1 to BD8 via the first to eighth output channels 241a to 241h. And outputs eighth drive signals. The first output channel 241a is electrically connected to the first light emitting blocks 1a to 8a of the driving blocks BD1 to BD8 through the first switching unit 242, The first switching unit 242 time-divides the first driving signal transmitted from the first output channel 241a and transmits the first driving signal to the first light emitting blocks 1a to 8a. When the switching elements S11, S12, ..., S18 are turned on, the first light emitting blocks 1a to 8a are turned on by applying the first driving signal. When the first light emitting blocks 1a to 8a are turned off, The drive signal is interrupted and turned off.

In the same manner, the second switching unit 243 time-divides the second driving signal transmitted from the second output channel 241b and transmits the second driving signal to the second light emitting blocks 1b to 8b. The third switching unit 244 time-divides the second driving signal transmitted from the third output channel 241c and transmits the second driving signal to the third light emitting blocks 1c to 8c. The fourth switching unit 245 time-divides the fourth driving signal transmitted from the fourth output channel 241d and transmits the fourth driving signal to the fourth light emitting blocks 1d through 8d. The fifth switching unit 246 time-divides the fifth driving signal transmitted from the fifth output channel 241e and transmits the fifth driving signal to the fifth light emitting blocks 1e through 8e. The sixth switching unit 247 time-divides the sixth driving signal transmitted from the sixth output channel 241f and transmits the sixth driving signal to the sixth light emitting blocks 1f through 8f. The seventh switching unit 248 time-divides the seventh driving signal transmitted from the seventh output channel 241g and transmits the seventh driving signal to the seventh light emitting blocks 1g through 8g. The eighth switching unit 249 time-divides the eighth driving signal transmitted from the eighth output channel 241h and transmits the eighth driving signal to the eighth light emitting blocks 1h through 8h.

The light emission driving unit 240 drives the light emitting blocks of the light source module 200 using the brightness level provided from the brightness determination unit 230. For example, the light emission driving part 240 boosts the supply time of the driving signal applied to the first light emitting area based on the first luminance level of the first light emitting area, thereby boosting the first light emitting area with a high luminance . The light emitting driver 240 drives the light emitting blocks included in the second light emitting area at a normal brightness by using the second brightness level corresponding to the second light emitting area.

6 is a timing chart of an output signal of the light emitting driver shown in FIG. Hereinafter, the light-emitting blocks of the light source module 200 are all turned on.

5 and 6, the driving chip 241 is connected to the first through eighth driving blocks BD1,..., 241h through first through eighth output channels 241a, 241b, ..., 241h. ..., and BD8, respectively.

When the first to eighth switching elements S11, S12, ..., S18 of the first switching unit 242 connected to the first output channel 241a are turned on, the driving blocks BD1 , ..., BD8 are applied to the first light emitting blocks 1a to 8a. That is, the first light emitting blocks 1a to 8a emit light during the turn-on period of the first to eighth switching elements S11, S12, ..., S18.

When the first to eighth switching elements S21, S22, ..., S28 of the second switching unit 243 connected to the second output channel 241b are turned on, the driving blocks BD1 , ..., BD8 are applied to the second light emitting blocks 1b to 8b. That is, the second light emitting blocks 1b to 8b emit light during the turn-on period of the first to eighth switching elements S21, S22, ..., S28.

In the same manner, the first to eighth switching elements S31, S32, ..., S38 of the third switching unit 244 are connected to the third light emitting block of the driving blocks BD1, ..., BD8, The first to eighth switching elements S41, S42, ..., S48 of the fourth switching unit 245 applies the third driving signal to the driving blocks (1c to 8c) The first to eighth switching elements S51 and S52 of the fifth switching unit 246 apply the fourth driving signals to the fourth light emitting blocks 1d to 8d of the first, ..., S58 applies the fifth driving signal to the fifth light emitting blocks 1e to 8e of the driving blocks BD1, ..., BD8, and the sixth switching unit 247, The first to eighth switching elements S61, S62, ..., S68 of the driving blocks BD1, ..., BD8 are connected to the sixth light emitting blocks 1f to 8f of the driving blocks BD1, The first to eighth switching elements S71, S72, ..., S78 of the seventh switching unit 248 apply a signal to the driving blocks BD1, ..., BD8, The first to eighth switching elements S81, S82, ..., S88 of the eighth switching unit 249 apply the seventh driving signals to the light-emitting blocks 1g to 8g, The eighth driving signal is applied to the eighth light emitting blocks 1h through 8h of the blocks BD1 through to BD8.

As a result, the first driving block BD1 is driven in the first section T1 of one frame, the second driving block BD2 is driven in the second section T2, and the third section T3 is driven in the second section T2. The third driving block BD3 is driven in the eighth period T8 and the eighth driving block BD8 is driven in the eighth period T8. Further, each of the light emitting blocks is configured to emit light for at least 1/8 frame.

Hereinafter, a boosting driving method using the light emitting driver 240 shown in FIG. 5 will be described. Here, the case where the first light emitting region displays white gradation and the second light emitting region 830 displays black gradation is taken as an example.

7A is a circuit diagram for explaining a driving method according to an example of the light emission driving part. 7B is a timing chart of the output signal of the light emitting driver shown in FIG. 7A.

1 and 7A, the region determining unit 220 may include a first light emitting region 810 for driving the light source module 200 at a high luminance by comparing representative values of display blocks with a reference value, The second light emitting region 830 is formed.

The first light emitting region 810 includes light emitting blocks having a representative gray level value equal to or greater than a reference value and the second light emitting region 830 includes light emitting blocks having a representative gray level value smaller than the reference value.

The first light emitting region 810 includes the eighth light emitting block 2h of the second driving block BD2, the fifth and seventh light emitting blocks 3e and 3g of the third driving block BD3, The second and fourth light emitting blocks 6b and 6d of the driving block BD6 and the first and third light emitting blocks 7a and 7c of the seventh driving block BD7. The second light emitting region 830 includes light emitting blocks of the light source module 200 excluding the first light emitting region 810.

The driving chip 241 outputs first to eighth driving signals through the first to eighth output channels 241a, ..., and 241h. The first to eighth switching units 242, ..., and 249 connected to the first to eighth output channels 241a to 241h receive the first to eighth driving signals, Lt; / RTI &gt; The switching elements corresponding to the first light emitting region 810 are turned on so that the light emitting blocks 8h of the first light emitting region 810 are turned on, , 3e, 3g, 6b, 6d, 7a and 7c, and the switching elements corresponding to the second light emitting region 830 are turned off to turn off the light emitting blocks of the second light emitting region 830.

For example, the second switching device S82 of the eighth switching unit 249 is turned on to light the eighth light emitting block 2h of the second driving block BD2. The third switching device S35 of the fifth switching unit 246 is turned on to turn on the fifth light emitting block 3e of the third driving block BD3. The third switching device S73 of the seventh switching unit 248 is turned on to light the seventh light emitting block 3g of the third driving block BD3. In the same manner, the sixth switching element S26 of the second switching section 243, the sixth switching element S46 of the fourth switching section 245, the seventh switching element S17 of the first switching section 242, And the seventh switching device S37 of the third switching unit 244 are turned on to turn on the light emitting blocks 6b, 6d, 7a and 7c.

On the other hand, the switching elements electrically connected to the light emitting blocks of the second light emitting region 830 are turned off to turn off the light emitting blocks. Here, it is illustrated that the light emitting blocks of the second light emitting region 830 are turned off as the black gradation is displayed corresponding to the second light emitting region 830.

However, when an image of a halftone level is displayed corresponding to the second light emitting region 830, the switching elements electrically connected to the light emitting blocks of the second light emitting region 830 are connected to the second light emitting region 830 The second light emitting region 830 is turned on at a luminance corresponding to the second luminance level. The second brightness level may be determined for each light emitting block of the second light emitting region 830.

7b, each of the light emitting blocks 2h, 3e, 3g, 6b, 6d, 7a, and 7c of the first light emitting region 810 may be lit for at least a 1/8 frame period.

On the other hand, the turn-on times of the switching elements S82, S53, S73, S26, S46, S17 and S37 for applying driving signals to the light-emitting blocks 2h, 3e, 3g, 6b, 6d, 7a, May be expanded to boost the luminance of the first light emitting region 810.

1 and 2, the brightness determining unit 270 determines the brightness of the first light emitting region 810 as the first light emitting region 810 occupies about 11% of the total size, Lt; th &gt; The light emission driving unit 240 may turn on and off the switching elements S82, S53, S73, S26, S46, S17, and S37 that transmit driving signals to the first light emitting region 810 based on the first luminance level. And the first emission region is boosted to a luminance corresponding to the first luminance level.

When the turn-on time of the switching elements is extended to a maximum extended length, one frame, the first light emitting region can be boosted to a luminance corresponding to a maximum luminance level 160. [ The light emitting driver 240 extends the turn-on time of the switching elements S82, S53, S73, S26, S46, S17 and S37 by about 80% of one frame. Accordingly, the first light emitting region 810 may be boosted to a luminance corresponding to the first luminance level, that is, 130. FIG.

8A is a circuit diagram according to another driving example of the light emitting driver shown in FIG. 8B is a timing chart of the output signal of the light emitting driver shown in FIG. 8A.

Referring to FIGS. 8A and 8B, the first light emitting region 810 includes second, third, fourth, fifth, sixth, seventh, and eighth light emitting blocks 810 of the second driving block BD2. (2b, 2c, 2d, 2e, 2f 2g, 2h). The second light emitting region 830 includes light emitting blocks of the light source module 200 except for the first light emitting region 810.

The second switching device S22 of the second switching unit 243 is turned on to turn on the second light emitting block 2b of the second driving block BD2. The second switching device S32 of the third switching unit 244 is turned on to light the third light emitting block 2c of the second driving block BD2. The second switching device S42 of the fourth switching unit 245 is turned on to turn on the fourth light emitting block 2d of the second driving block BD2. In the same manner, the second switching device S62 of the fifth switching unit 246, the second switching device S62 of the sixth switching unit 247, the second switching device S72 of the seventh switching unit 248, And the second switching device S82 of the eighth switching unit 249 are turned on to turn on the fifth, sixth, seventh and eighth light emitting blocks 2e, 2f, 2g and 2h, .

The light emission driving unit 240 may extend the turn-on time of the switching elements S22, S32, S42, S52, S62, S72, and S82 for a maximum of one frame, To the luminance corresponding to the luminance level.

9A is a circuit diagram according to another driving example of the light emission driving unit shown in FIG. 9B is a timing chart of the output signal of the light emitting driver shown in FIG. 9A.

9A and 9B, the first light emitting region 810 includes the sixth, seventh and eighth light emitting blocks 2f, 2g and 2h of the second driving block BD2 and the sixth driving block Second, third, and fourth light emitting blocks 6a, 6b, 6c, 6d of the first, second, third,

The second switching device S62 of the sixth switching unit 247 is turned on to light the sixth light emitting block 2f of the second driving block BD2. The second switching device S72 of the seventh switching unit 248 is turned on to light the seventh light emitting block 2g of the second driving block BD2. The second switching device S82 of the eighth switching unit 249 is turned on to light the eighth light emitting block 2h of the second driving block BD2. In the same manner, the sixth switching element S16 of the first switching unit 242, the sixth switching element S26 of the second switching unit 243, the sixth switching element S6 of the third switching unit 244 And the seventh switching device S46 of the fourth switching unit 245 are turned on to turn on the first, second, third, and fourth light emitting blocks 6a , 6b, 6c, 6d are turned on.

The light emission driving part 240 may extend the turn-on time of the switching elements S62, S72, S82, S16, S26, S36 and S46 for a maximum of one frame, To the luminance corresponding to the luminance level.

10 is a flowchart illustrating a local dimming method of the light source module shown in FIG.

Referring to FIGS. 1 and 10, the representative value calculating unit 210 calculates a representative tone value of the display block D corresponding to the light-emitting block B using a video signal (step S110). The representative gray scale value may be an average gray scale value, a maximum gray scale value, a minimum gray scale value, a root mean square (RMS) of the gray scale value of the image signal, or the like. The representative tone value may be determined by various methods.

The area determining unit 220 divides the light emitting blocks B of the light source module 200 into a first light emitting area and a second light emitting area by comparing the representative gray scale value with a reference value. Specifically, if the representative gray scale value is greater than or equal to the reference value, the corresponding light emitting block is determined as the first light emitting area having the maximum brightness. If the representative gray scale value is smaller than the reference value, (Step S210). For example, the reference value is the white gradation value, the maximum luminance is the luminance of the white gradation image, and the general luminance is the luminance of the intermediate gradation image.

The area determining unit 220 sums the sizes of the light emitting blocks whose representative tone value is larger than the reference value (step S310). These processes are repeated until one frame is completed (step S410).

The brightness determining unit 230 determines a second brightness level of the light emitting block included in the second light emitting area (step S510). The second brightness level is determined using a gamma curve and a representative gray-scale value of the light-emitting block. The gamma curve includes a luminance distribution according to the representative gray-scale value. In addition, the brightness determining unit 230 may compensate the second brightness level in various ways in consideration of the brightness level of the adjacent light-emitting blocks. For example, a compensation matrix having a size of 3 × 3, 16 × 16, or P × Q (P, Q is a natural number) may be applied to compensate the second luminance level of the light emitting block.

The brightness determining unit 230 determines the first brightness level of the first light emitting region according to the ratio of the size of the first light emitting region to the total size of the frame (Step S520). If the size of the first light emitting region is small, the first luminance level is increased, and if the size of the first light emitting region is large, the first luminance level is made small.

The light emission driving unit 240 drives the light emitting blocks included in the first light emitting area and the light emitting blocks included in the second light emitting area using the first and second brightness levels (step S610). The specific driving method of the light emitting driver 240 is the same as that described with reference to FIGS. 5 to 9B, and thus a detailed description thereof will be omitted.

11 is a graph showing the relationship between the size of the light emitting region and the luminance.

Referring to FIG. 11, the first curve Curve 1 is a curve showing the relationship between the size of the light emitting region and the brightness according to the liquid crystal display of the embodiment, and the second curve Curve 2 is a curve Is a curve showing the relationship between the size of the region and the luminance.

When the first and second curves 1 and 2 are compared, the comparative example always has a constant luminance level of '100' regardless of the size of the light emitting region when the representative gray scale value indicates the maximum value '100'. On the other hand, in the embodiment, when the representative gray scale value indicates the maximum value, the brightness level is varied according to the size of the light emitting area. That is, as the size of the light emitting region decreases, the brightness level exponentially increases, and as the size of the light emitting region increases, the brightness level decreases.

That is, the light source module of the comparative example emits light with a luminance corresponding to a constant luminance level '100', regardless of the size of the light emitting region that supplies light of the maximum luminance. However, the light source module of the above embodiment emits light with a brightness corresponding to a brightness level that increases as the size of the light emitting region that supplies light with the maximum brightness decreases. As a result, the liquid crystal display device of the above-described example was superior to the comparative liquid crystal display device in the contrast ratio.

In the comparative example, the maximum luminous intensity region has a luminance level of about 100 at a point A having the maximum luminance, but the embodiment has a luminance of about 55 at the point A 'where the maximum luminous intensity region has the maximum luminance I had a level. Therefore, the liquid crystal display device of the embodiment can reduce the user's glare phenomenon as compared with the liquid crystal display device of the comparative example.

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.

1 is a block diagram of a display device according to an embodiment of the present invention.

FIG. 2 is a graph showing the relationship between the size of the light emitting region and the luminance applied to the display device of FIG.

FIG. 3A is a plan view of an image displayed on the display panel of FIG. 1; FIG.

3B is a plan view of the light source module corresponding to the image of FIG. 3A.

4A is a plan view of an image according to another example displayed on the display panel of FIG.

4B is a plan view of the light source module corresponding to the image of FIG. 4A.

5 is a circuit diagram of the light emitting driver shown in FIG.

6 is a timing chart of an output signal of the light emitting driver shown in FIG.

7A is a circuit diagram according to one example of driving operation of the light emitting driver shown in FIG.

7B is a timing chart of the output signal of the light emitting driver shown in FIG. 7A.

8A is a circuit diagram according to another driving example of the light emitting driver shown in FIG.

8B is a timing chart of the output signal of the light emitting driver shown in FIG. 8A.

9A is a circuit diagram according to another driving example of the light emission driving unit shown in FIG.

9B is a timing chart of the output signal of the light emitting driver shown in FIG. 9A.

10 is a flowchart illustrating a local dimming method of the light source module shown in FIG.

11 is a graph showing the relationship between the size of the light emitting region and the luminance.

       Description of the Related Art

100: display panel 110: timing controller

130: panel driver 200: light source module

210: representative value calculating unit 220: area determining unit

230: luminance determination unit 240: light emission driving unit

241: Driving chip

241a to 241h: first to eighth output channels

242 to 249: First to eighth switching units

Claims (23)

Each of the driving blocks is divided into a plurality of driving blocks each having a matrix structure of I x J (I, J is a natural number), and each driving block is composed of a plurality of light emitting blocks having a matrix structure of i x j In a light source local dimming method for driving a light source for each light emitting block, Generating the ix j driving signals; Dividing each driving signal into I 占 개 intervals and applying the divided driving signals to each of the driving blocks; And The luminance of the first light emitting region is increased and driven as the size of the first light emitting region corresponding to the display region displaying the maximum luminance is decreased and the luminance of the first light emitting region is increased as the size of the first light emitting region is larger, Is reduced and driven. delete The method according to claim 1, Determining a light emitting block corresponding to the representative tone value as the first light emitting region when the representative tone value of an image calculated from a video signal received from the outside is equal to or greater than a preset reference value; Determining a first luminance level of the first emission region according to a size of the first emission region; And Further comprising driving the first light emitting region using the first brightness level, Wherein the first luminance level is determined to be larger as the size of the first emission region is smaller and the first luminance level of the first emission region is determined to be smaller as the size of the first emission region is larger. Way. 4. The method of claim 3, wherein when the size of the first light emitting region is the minimum, the first luminance level is maximized. delete 2. The method of claim 1, wherein one frame includes IxJ periods and applies the driving signal to one light-emitting block included in one driving block for one period. 7. The method of claim 6, wherein the step of applying each of the I x J driving blocks comprises: Wherein the driving signal is applied to the light-emitting block of the first light-emitting region for a time extended by a maximum of IXJ times. The method of claim 3, Determining a light emitting block corresponding to the representative tone value as a second light emitting area if the representative tone value of the image is smaller than the reference value; Determining a second luminance level of a light emitting block included in the second light emitting area by using the representative gray scale value and a gamma curve; And And driving the second light emitting region according to the second luminance level. A light source module for providing light to a display panel divided into a plurality of display blocks and including a plurality of light emitting blocks corresponding to the display blocks; And The brightness of the first light emitting region is increased and driven as the size of the first light emitting region of the light source module corresponding to the region of the display panel in which the image of the maximum brightness is displayed is smaller and the larger the size of the first light emitting region, And a local dimming driver for driving and reducing the brightness of the first light emitting area, The light-emitting blocks are divided into a plurality of driving blocks each having a matrix structure of IxJ (I, J is a natural number), and each driving block includes a plurality of light-emitting blocks having a matrix structure of ixj (i, j is a natural number) Blocks, The local dimming driver includes a light emitting driver, and the light emitting driver A driving chip including the ixj output channels and outputting ixj driving signals to the output channels; And Wherein the I x J switching elements are connected to each output channel in parallel, and the I x J switching elements switch the driving signal applied to the output channel to the I x J driving blocks by time division / RTI &gt; 10. The image display apparatus according to claim 9, wherein the local dimming driver A representative value calculation unit for calculating a representative gray level value of an image corresponding to each display block with a video signal received from the outside; An area determining unit determining the light emitting block corresponding to the representative gray scale value as the first light emitting area when the representative gray scale value is equal to or greater than a reference value; Determines the first luminance level of the first light emitting region, determines the first luminance level if the first light emitting region is small and determines the first luminance level to be small if the size of the first light emitting region is large A luminance determining unit And And the light emitting driver driving the light emitting block included in the first light emitting region according to the first brightness level. The apparatus of claim 10, wherein the region determining unit determines the light emitting block corresponding to the representative gray level value as the second light emitting region when the representative gray scale value is smaller than the reference value, Wherein the brightness determining unit determines a second brightness level of the light emitting block included in the second light emitting area by using the representative gray scale value and the gamma curve, Wherein the light emitting driver drives the light emitting block included in the second light emitting area according to the second brightness level. delete delete The driving method according to claim 9, wherein one frame includes IxJ periods, and one switching element of the IxJ switching elements is turned on during one section to form one light-emitting block To the light source device. The organic light emitting display according to claim 14, wherein the light emitting driver increases a turn-on time of a switching element connected to the light emitting block included in the first light emitting region by a maximum of IXJ times to increase the brightness of the light emitting block Light source device. A display panel displaying an image and divided into a plurality of display blocks; A light source module for providing light to a display panel divided into a plurality of display blocks and including a plurality of light emitting blocks corresponding to the display blocks; And The brightness of the first light emitting region is increased and driven as the size of the first light emitting region of the light source module corresponding to the region of the display panel in which the image of the maximum brightness is displayed is smaller and the larger the size of the first light emitting region, And a local dimming driver for driving and reducing the brightness of the first light emitting area, The light-emitting blocks are divided into a plurality of driving blocks each having a matrix structure of IxJ (I, J is a natural number), and each driving block includes a plurality of light-emitting blocks having a matrix structure of ixj (i, j is a natural number) Blocks, The local dimming driver includes a light emitting driver, and the light emitting driver A driving chip including the ixj output channels and outputting ixj driving signals to the output channels; And The IxJ switching elements connected in parallel to the respective output channels, and the IxJ switching elements switching the driving signal applied to the output channel to the IxJ driving blocks by time division A display comprising. 17. The apparatus of claim 16, wherein the local dimming driver A representative value calculation unit for calculating a representative gray level value of an image corresponding to each display block with a video signal received from the outside; An area determining unit determining the light emitting block corresponding to the representative gray scale value as the first light emitting area when the representative gray scale value is equal to or greater than a reference value; Determines the first luminance level of the first light emitting region, determines the first luminance level if the first light emitting region is small and determines the first luminance level to be small if the size of the first light emitting region is large A luminance determining unit And And the light emitting driver driving the light emitting block included in the first light emitting region according to the first luminance level. delete The driving method of claim 16, wherein one frame includes IxJ periods, and one switching element of the IxJ switching elements is turned on during one interval to form one light-emitting block To the display device. The organic light emitting display according to claim 19, wherein the light emitting driver increases the turn-on time of the switching element connected to the light emitting block included in the first light emitting area by a maximum of IXJ times to increase the brightness of the light emitting block Display device. In a light source local dimming method in which a driving block including a plurality of light emitting blocks having a matrix structure of ixj (i, j is a natural number) drives a light source having I × J (I, J is a natural number) matrix structure, generating i x j driving signals; And Dividing each driving signal into I 占 개 intervals, and applying the divided driving signals to the I 占 개의 driving blocks, respectively. 22. The method of claim 21, wherein one frame includes IxJ periods and the driving signal is applied to one light-emitting block included in one driving block during one period. 23. The method of claim 22, wherein applying each of the IxJ driving blocks comprises: Wherein the driving signal is applied to the light-emitting block for a time extended by a maximum of IXJ times.

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