KR100921518B1 - Led backlight system - Google Patents

Abstract

The present invention relates to an LED backlight system capable of independently controlling the driving of each LED block by dividing a plurality of LED arrays included in the LED backlight into a plurality of LED blocks grouped by a predetermined number. A duty ratio of a plurality of LED blocks including a plurality of peripheral blocks, and LED driving pulses corresponding to each LED block, including a reference driving pulse corresponding to the reference block and a peripheral driving pulse corresponding to each peripheral block. An LED driver for driving each LED block with a driving force according to the present invention, a first storage unit storing data about color coordinates and luminance of light in contrast to light having a plurality of predetermined amounts of light based on a CIE standard color coordinate system; Each LED block stores a look up table for the duty ratio of each LED drive pulse to generate light with a predetermined number of luminance and A second storage unit, a sensing unit for sensing an amount of light generated from the reference block and outputting a sensing light amount, and a reference corresponding to a luminance of a desired light based on a look-up table of the second storage unit A first duty ratio interpolator for interpolating a duty ratio of a driving pulse or adjusting a duty ratio of the reference driving pulse so that the amount of detected light matches a color coordinate and luminance of a desired light based on data of the first storage unit, and the Interpolating the duty ratio of each peripheral driving pulse in response to the desired brightness of the light based on the lookup table of the second storage unit, or outputting the first duty ratio interpolator based on the lookup table of the second storage unit An LED backlight system having a second duty ratio interpolation unit that interpolates the duty ratio of each peripheral driving pulse in response to a duty ratio of a pulse is provided.

LED backlight, dimming control, interpolation

Description

LED backlight system {LED BACKLIGHT SYSTEM}

The present invention relates to an LED backlight system, and more particularly, to divide the plurality of LED arrays included in the LED backlight into a plurality of LED blocks grouped by a predetermined number of LED backlights to independently control driving of each LED block. It's about the system.

Backlight is a device that illuminates a display panel. Recently, display systems using LCDs such as LCD monitors and LCD TVs are being progressed from the backlight method using LEDs using a conventional CCFL (Cold Cathde Fluorescent Lamp).

CCFL-based backlights are disadvantageous because they use mercury, which is harmful to the environment, slow in response, 75% lower in color reproducibility than the National Television System Committee (NTSC), and generates preset white light.

On the other hand, LED-based backlights have a response speed of several nanoseconds without the use of environmentally harmful substances, enabling high-speed response, impulsive driving, color reproducibility over 100% of NTSC, and red color. By adjusting the amount of light of the blue and green LEDs, the color coordinates and luminance of light generated from the backlight can be arbitrarily adjusted.

This advantage of the LED backlight is possible due to the characteristic operation of the LED backlight to produce a white light by properly mixing the red light, blue light and green light. Therefore, the LED backlight includes a plurality of red LED arrays for producing red light, a plurality of blue LED arrays for producing blue light, and a plurality of green LED arrays for producing light of green LED.

That is, the LED backlight generates white light in which red light, blue light, and green light are appropriately mixed through an operation of properly driving a plurality of red LED arrays, a plurality of blue LED arrays, and a plurality of green LED arrays, respectively.

By including multiple red LED arrays, multiple green LED arrays, and multiple blue LED arrays inside the LED backlight, the LED backlight can have the same advantages as described above. New problems may arise.

First, since each LED array emits the same color light among each LED array included in the LED backlight, it is generated from each LED array emitting the same color light due to external factors or process factors. Light brightness can vary by 15% to 20%.

For example, even when the red light is emitted from the plurality of red LED arrays using the same control signal, the brightness of the red light generated in each red LED array may be about 15% to 20%.

The same applies to a large number of blue LED arrays and a plurality of green LED arrays. Therefore, even if the red LED array, the blue LED array, and the green LED array are uniformly arranged in the entire area of the LED backlight, the LED back The brightness of the light emitted from a randomly selected area among a plurality of LED arrays arranged in the light, which means that the red LED array, the blue LED array, and the green LED array are uniformly maintained, always maintains the same quality (Unifomity). The problem arises that it is difficult to do.

In addition, the brightness of the light emitted from the LED backlight may be different from the desired light due to the above-mentioned problem. In this case, the feedback method using the color sensor is used to determine the ratio of the red light to blue light to green light of the white light generated by the LED backlight using the color sensor. Therefore, it means a method of properly changing the driving force for driving the red LED array, blue LED array and green LED array.

However, the feedback method using the color sensor is a method that consumes several hundred milliseconds (ms) in a relatively large amount of time, which causes each LED element included in the LED backlight to have a relatively fast number of nanoseconds (ns). In spite of the response speed, in the display device using the LED backlight, the brightness change control of the LED backlight that is repeated at least 60 to 120 times per second to obtain a high contrast ratio, that is, the LED backlight There is a problem that it is impossible to perform the light dimming control.

The present invention is proposed to solve the above problems of the prior art, grouping a plurality of LED arrays included in the LED backlight by a predetermined number-red LED array, blue LED array and green LED array are uniformly included- Therefore, the purpose of the present invention is to provide a LED backlight system that can be divided into a plurality of LED blocks and independently control the brightness of light generated from each LED block.

Also, instead of using a feedback method using a color sensor when the luminance of light to be generated in the LED block is changed, a look-up table of signals for controlling driving of each LED block according to the luminance change of the generated light. The purpose of the present invention is to provide an LED backlight system that can control the change in brightness of the LED backlight.

According to an aspect of the present invention for achieving the above object, a plurality of LED blocks including one reference block and a plurality of peripheral blocks; LED for driving each LED block with a driving force according to the duty ratio of the LED driving pulse corresponding to each LED block, including the reference driving pulse corresponding to the reference block and the peripheral driving pulse corresponding to each peripheral block. Drive means; First storage means for storing data about color coordinates and luminance of light in contrast to light having a plurality of predetermined amounts of light based on a CIE standard color coordinate system; Second storage means for storing a look-up table for the duty ratio of each LED drive pulse for each LED block to generate light having a predetermined plurality of brightnesses; Sensing means for sensing an amount of light generated by the reference block and outputting a detected amount of light; Interpolating the duty ratio of the reference driving pulse in response to the desired brightness of the light based on the look-up table of the second storage means, or detecting a color coordinate of the desired light based on the data of the first storage means; First duty ratio interpolation means for adjusting a duty ratio of the reference driving pulse to match luminance; Interpolating the duty ratio of each peripheral driving pulse in response to the desired brightness of the light based on the look up table of the second storage means, or interpolating the first duty ratio based on the look up table of the second storage means. An LED backlight system having a second duty ratio interpolation means for interpolating the duty ratio of each peripheral drive pulse corresponding to the duty ratio of the output pulse of the means.

According to another aspect of the present invention for achieving the above object, a plurality of LED blocks with a driving force according to the duty ratio of a plurality of LED driving pulses-including one reference driving pulse and a plurality of peripheral driving pulses. Driving one reference block and a plurality of peripheral blocks; Creating a look up table for the duty ratio of each LED drive pulse for each LED block to generate light having a predetermined plurality of brightnesses; Generating data about color coordinates and luminance of light compared to light having a plurality of predetermined amounts of light based on a CIE standard color coordinate system; Interpolating the duty ratio of each of the LED driving pulses corresponding to the desired brightness of the light based on the lookup table for the duty ratio; Sensing a light amount of light generated in the reference block and outputting a detected light amount; Outputting an adjusted reference driving pulse by adjusting a duty ratio of the reference driving pulse so that the detected light quantity matches the color coordinate and luminance of a desired light based on the data about the color coordinate and the luminance; And interpolating the duty ratio of each peripheral driving pulse in response to the duty ratio of the adjusted reference driving pulse based on the look-up table for the duty ratio.

According to the present invention, a plurality of LED arrays included in the LED backlight are grouped by a predetermined number-the red LED array, the blue LED array, and the green LED array are uniformly included-and divided into a plurality of LED blocks, and each LED block. Independently controlling the brightness of the light emitted from the LED backlight has the effect of generating the light having the same brightness in the entire area.

In addition, instead of using a feedback method using a color sensor when the luminance of light to be generated in the LED block is changed, a target light is applied to each LED block based on a look-up table in which the duty ratio of the LED driving pulse is stored. It is possible to control dimming control in LED backlight system by controlling the brightness change of LED backlight by interpolating each LED driving pulse to generate-relatively fast brightness change control at least 60 to 120 times per second. There is.

Hereinafter, with reference to the accompanying drawings will be described a preferred embodiment of the present invention. Therefore, the present invention is not limited to the embodiments disclosed below, but can be implemented in various different forms, only the embodiments are intended to complete the disclosure of the present invention and to those skilled in the art the scope of the present invention It is provided to inform complete.

1 is a block diagram illustrating an LED backlight system according to an embodiment of the present invention.

Referring to FIG. 1, an LED backlight system according to an exemplary embodiment of the present invention includes a plurality of LED blocks 100 and 110 <including one reference block 100 and a plurality of peripheral blocks 110 <0: N>. 0: N>) and LED driving pulses corresponding to each LED block 100, 110 <0: N> (REF_DR_PUL, ARD_DR_PUL <0: N>)-Reference driving pulses corresponding to the reference block 100 (REF_DR_PUL) ) And peripheral driving pulses (ARD_DR_PUL <0: N>) corresponding to each peripheral block (110 <0: N>)-each LED block (100,) with a driving force according to the duty ratio of LEDs (120, 130 <0: N>) for driving 110 <0: N>) and light contrasted to light having a plurality of predetermined amounts of light based on the CIE Commission Internationale deI'Eclairage. The first storage unit 140 storing data about color coordinates and luminance LC_DATA, and each of the LED blocks 100 and 110 <0: N> for generating light having a plurality of predetermined luminances. LED drive pulse (REF_DR_PUL, ARD_DR_PUL <0: N>) and the second storage unit 150 that stores the lookup table for the duty ratio (CD_TABLE) and the amount of light generated from the reference block 100 to detect the amount of light (LIGHT_SENS) The duty ratio of the reference driving pulse REF_DR_PUL in response to the luminance of the desired light PURPOSE_LIGHT on the basis of the lookup table CD_TABLE of the second storage unit 150 and the second storage unit 150. Interpolate or adjust the duty ratio of the reference driving pulse REF_DR_PUL so that the detected light amount LIGHT_SENS matches the target color coordinates and luminances PURPOSE_LIGHT and PURPOSE_COLOR based on the data LC_DATA of the first storage unit 140. Peripheral driving pulses ARD_DR_PUL <0: corresponding to the luminance PURPOSE_LIGHT of the target light based on the lookup table CD_TABLE of the first duty ratio interpolation unit 170 and the second storage unit 150. N>) or the first duty ratio interpolation unit based on the look-up table CD_TABLE of the second storage unit 150. The second duty ratio interpolation unit 180 interpolates the duty ratio of each peripheral driving pulse ARD_DR_PUL <0: N> in response to the duty ratio of the output pulse REF_DR_PUL of 170. The apparatus further includes a third storage unit 190 for storing information about the color coordinates PURPOSE_COLOR of the target light and the luminance PURPOSE_LIGHT of the desired light. In addition, the output pulse REF_DR_PUL of the first duty ratio interpolator 170 and the output pulse ARD_DR_PUL <0: N> of the second duty ratio interpolator 180 are connected to the LED drivers 120 and 130 <. 0: N>, it is further provided with a pulse transfer unit 195.

Here, the target color coordinates (PURPOSE_COLOR) and the target brightness of the light (PURPOSE_LIGHT) has a predetermined initial value applied in the initial operation, the operation of the target light luminance (PURPOSE_LIGHT) is applied from the outside It changes to the luminance value (OUT_LIGHT) of the light. Of course, in the operation after the initial operation, if there is no luminance OUT_LIGHT value of the externally applied light, the initial luminance of the target light PURPOSE_LIGHT is maintained as it is. In addition, the initial values of the color coordinates of the desired light (PURPOSE_COLOR) and the desired brightness of the light (PURPOSE_LIGHT) are determined when the LED backlight system is designed and can be artificially changed by the user later, but the LED backlight The value does not change due to the operation of the system.

The first duty ratio interpolator 170 may include a second storage unit when the luminance OUT_LIGHT of the externally applied light is different from the target luminance PURPOSE_LIGHT stored in the third storage unit 190. The duty ratio of the reference driving pulse REF_DR_PUL is interpolated based on the lookup table CD_TABLE of 150 to correspond to the desired luminance of the light PURPOSE_LIGHT.

In addition, the first duty ratio interpolation unit 170 may have the same brightness as the luminance OUT_LIGHT of the externally applied light that is stored in the third storage unit 190 or the external luminance of the light. When the luminance OUT_LIGHT is not input, the reference driving pulse REF_DR_PUL such that the detected light quantity LIGHT_SENS matches the target color coordinates and luminances PURPOSE_COLOR and PURPOSE_LIGHT based on the data LC_DATA of the first storage unit 140. Adjust the duty ratio.

The second duty ratio interpolation unit 180 may store the second storage unit when the luminance OUT_LIGHT of the externally applied light is different from the target luminance PURPOSE_LIGHT stored in the third storage unit 190. The duty ratio of each peripheral drive pulse ARD_DR_PUL <0: N> is interpolated based on the lookup table CD_TABLE of (CD_TABLE) in correspondence with the desired luminance (PURPOSE_LIGHT) of the light.

In addition, the second duty ratio interpolator 180 may have the same brightness as the luminance OUT_LIGHT of the externally applied light, which is stored in the third storage unit 190, or equal to the luminance PURPOSE_LIGHT. When the luminance OUT_LIGHT is not input, each peripheral drive pulse ARD_DR_PUL corresponding to the duty ratio of the output pulse REF_DR_PUL of the first duty ratio interpolation unit 170 based on the look-up table CD_TABLE of the second storage unit. The duty ratio of <0: N>) is interpolated.

In order to implement the above-described operation, the data LC_DATA of the first storage unit 140, the look-up table CD_TABLE of the second storage unit 150, and the target color coordinates of the light of the third storage unit 190 ( PURPOSE_COLOR) and the initial value of the desired luminance of the light PURPOSE_LIGHT are stored in an internal nonvolatile memory element, for example, a flash memory. In addition, the luminance OUT_LIGHT of the light applied to the third storage unit 190 from the outside is stored in the volatile memory device.

That is, the third storage unit 190 includes both a volatile memory device and a nonvolatile memory device, and the nonvolatile memory device includes an initial value of a color coordinate (PURPOSE_COLOR) of a desired light and a luminance (PURPOSE_LIGHT) of a desired light. A value that can be artificially changed by the user but cannot be changed due to the operation of the LED backlight is stored, and the volatile memory device stores a value of externally applied light that is recognized as the desired brightness (PURPOSE_LIGHT). The luminance (OUT_LIGHT) value-the value that changes due to the operation of the LED backlight-is stored.

Referring to the operation of the LED backlight system according to an embodiment of the present invention based on the above configuration as follows.

2 is a flowchart illustrating the operation of the LED backlight system according to the embodiment of the present invention shown in FIG.

First, in order for the operation illustrated in FIG. 2 to be normally performed, the data LC_DATA of the first storage unit 140 and the lookup table CD_TABLE of the second storage unit 150 should be completed first.

That is, before the operation of the LED backlight system according to the embodiment of the present invention shown in FIG. 2 starts, each of the LED blocks 100 and 110 <0: N> generates light having a predetermined number of luminances. Creating a look-up table (CD_TABLE) for the duty ratio of each LED driving pulse (REF_DR_PUL, ARD_DR_PUL <0: N>) and storing it in the second storage unit 150; and CIE (Commission Internationale deI'Eclairage) An operation of creating and storing the data LC_DATA on the color coordinates and luminance of the light in contrast to the light having a predetermined amount of light based on the standard color coordinate system and storing it in the first storage unit 140 should be performed. The data used for this operation, that is, the lookup table (CD_TABLE) for the duty ratio of each LED driving pulse (REF_DR_PUL, ARD_DR_PUL <0: N>) and the color coordinates and luminance of the light (LC_DATA) Created during calibration of the light system.

In addition, in order for the operation illustrated in FIG. 2 to be normally performed, the sensing unit 160 should be located where the light generated from the reference block 100 can be best detected.

That is, the sensing unit 160 should detect the amount of light generated by the reference block 100 and output the detected amount of light LIGHT_SENS. In this case, since the light quantity of the light generated from the plurality of peripheral blocks 110 <0: N> does not have to be sensed, the sensing unit 160 does not detect the light of the peripheral blocks 110 <0: N>. This is the best position, and since it is impossible that light generated in the neighboring blocks 110 <0: N> does not affect the operation of the sensing unit 160 at all, the light mainly generated in the reference block 100 is The sensing unit 160 should be located where it can detect the best.

1 and 2, the operation of the LED backlight system according to an embodiment of the present invention includes a plurality of LED driving pulses REF_DR_PUL and ARD_DR_PUL <0: N> and one reference driving pulse REF_DR_PUL and a plurality of LED driving systems. Includes peripheral drive pulses of ARD_DR_PUL <0: N>-Multiple LED blocks (100, 110 <0: N>) with driving force according to duty ratio of-One reference block 100 and multiple peripheral blocks (110 <0: N>)-corresponding to the operation (210, 240) of driving and the luminance of the desired light (PURPOSE_LIGHT) on the basis of the look-up table (CD_TABLE) of the second storage unit 150 Interpolating the duty ratio of each of the LED driving pulses REF_DR_PUL and ARD_DR_PUL <0: N>, and the amount of detected light LIGHT_SENS based on the data LC_DATA of the first storage unit 140. Outputs the adjusted reference drive pulse (REF_DR_PUL) by adjusting the duty ratio of the reference drive pulse (REF_DR_PUL) to match the color coordinates of the light (PURPOSE_COLOR) and the desired brightness (PURPOSE_LIGHT). The peripheral driving pulses ARD_DR_PUL <0: N> in response to the duty ratio of the reference driving pulse REF_DR_PUL adjusted based on the operation 220 and the lookup table CD_TABLE of the second storage unit 150. Interpolating the duty ratio of the reference signal (230).

The operation of the LED backlight system according to the embodiment of the present invention illustrated in FIG. 2 described above is divided into two types depending on whether the luminance value of the desired light PURPOSE_LIGHT is changed or not.

At this time, the luminance value of the target light PURPOSE_LIGHT has a predetermined initial value applied in the initial operation, and the luminance of the target light PURPOSE_LIGHT when the luminance OUT_LIGHT is applied from the outside in the operation after the initial operation. ) Is replaced by the luminance OUT_LIGHT of the externally applied light.

That is, depending on whether the target luminance of the target light stored in the third storage unit 190 (PURPOSE_LIGHT) and the luminance value of the externally applied luminance (OUT_LIGHT) are the same or different values, two operations are performed. Divided into Of course, when there is no luminance OUT_LIGHT value of light applied from the outside, the luminance luminance PURPOSE_LIGHT value of the target light is the same as that does not change.

Specifically, in the initial operation performed immediately after the power is applied, the timing is input for the first time without the target color coordinate (PURPOSE_COLOR) and the target light luminance (PURPOSE_LIGHT), that is, stored in the nonvolatile memory device. Since the initial values of the color coordinates PURPOSE_COLOR of the target light and the luminance of the target light PURPOSE_LIGHT are applied, 'Yes' is selected in 'Is the luminance value of the target light changed?'.

Therefore, the duty of each of the LED driving pulses REF_DR_PUL and ARD_DR_PUL <0: N> in response to the initial value of the desired luminance PURPOSE_LIGHT of the light based on the lookup table CD_TABLE of the second storage unit 150. An operation of interpolating the ratio 200 is performed. Here, the operation 200 of interpolating the duty ratio of each of the LED driving pulses REF_DR_PUL and ARD_DR_PUL <0: N> will be described in detail.

First, the look-up table CD_TABLE of the second storage unit 150 is shown in Table 1 below.

Color coordinates and luminance (x, y, l) Duty ratio of the reference block 100 Duty ratio of the peripheral block (110 <0>)   … Duty ratio of the peripheral block (110 <N>) (x, y, 50) (Rref.0, Gref.0, Bref.0) (R0.0, G0.0, B0.0) (RN.0, GN.0, BN.0) (x, y, 100) (Rref.1, Gref.1, Bref.1) (R0.1, G0.1, B0.1) (RN.1, GN.1, BN.1) (x, y, 400) (Rref.2, Gref.2, Bref.2) (R0.2, G0.2, B0.2) (RN.2, GN.2, BN.2)

Referring to Table 1, each for generating light having predetermined color coordinates' x, y 'and a plurality of predetermined luminance '50, 100, 400' in each of the LED blocks 100, 110 <0: N>. It can be seen that the duty ratio of the LED driving pulses (REF_DR_PUL, ARD_DR_PUL <0: N>) is shown.

For example, in the reference block 100, if the color coordinates and the luminance are to emit light of '(x, y, 50)', the duty ratio of the reference driving pulse REF_DR_PUL is changed to '(Rref. 0, Gref. 0, Bref. 0) '.

Similarly, if the color coordinates and luminance of the (0, y, 400) color coordinates and luminance are generated in the 0th peripheral block 110 <0: N> of each peripheral block 110 <0: N>, the respective peripheral driving pulses The duty ratio of the 0th peripheral drive pulse ARD_DR_PUL <0> among (ARD_DR_PUL <0: N>) may be set to '(R0.2, G0.2, B0.2)'.

For reference, only a part of the lookup table CD_TABLE of the second storage unit 150 shown in Table 1 is illustrated. That is, in fact, the look-up table CD_TABLE of the second storage unit 150 generates the LED driving pulses for generating light having more luminance values in each of the LED blocks 100 and 110 <0: N>. Duty ratios of REF_DR_PUL and ARD_DR_PUL <0: N> are shown. At this time, the color coordinates 'x, y' presented in <Table 1> are color coordinates of light to be generated in each LED block 100, 110 <0: N>, where the color coordinates 'x, y' are defined by the designer. This can be a predefined value.

Therefore, when the initial value of the luminance of the target light PURPOSE_LIGHT is input, the corresponding luminance is found in the look-up table CD_TABLE of the second storage unit 150, and the initial value of the luminance of the desired light PURPOSE_LIGHT is obtained. The duty ratio of each of the LED driving pulses REF_DR_PUL and ARD_DR_PUL <0: N> for generating a corresponding light in each of the LED blocks 100 and 110 <0: N> may be determined.

Of course, there may occur a case where the initial value of the desired luminance PURPOSE_LIGHT is not found directly in the look-up table CD_TABLE of the second storage unit 150.

For example, in Table 1, the luminance of the light presented in the look-up table CD_TABLE of the second storage unit 150 is '50, 100, 400 ', and the initial value of the target luminance of the light PURPOSE_LIGHT is' In the case of 300 ', there may be no value in which the initial value of the luminance of the desired light PURPOSE_LIGHT and the luminance of the light presented in the look-up table CD_TABLE of the second storage unit 150 do not match.

In this case, each of the LED driving pulses REF_DR_PUL and ARD_DR_PUL <0: N> corresponding to the initial value of the desired luminance PURPOSE_LIGHT may be calculated using an interpolation method that predicts the value as follows.

3 is a graph illustrating interpolation of driving pulses corresponding to luminance according to an exemplary embodiment of the present invention.

Referring to FIG. 3, as shown in the above example, the luminance of light presented in the look-up table CD_TABLE of the second storage unit 150 in Table 1 is '50, 100, 400 ', but the luminance of the desired light is shown in Table 1. Even when the initial value of (PURPOSE_LIGHT) is '300', it can be seen that the value is predicted through interpolation.

Specifically, the graph shown in FIG. 3 is a point where the luminance of light is '50, 100, 400 'in the red LED included in the reference block 100 shown in the look-up table CD_TABLE of the second storage unit 150. And the duty ratio 'Rref.0, Rref.1, Rref.2' of the reference drive pulse (REF_DR_PUL) for generating light having '50', '100', and '400' luminances are connected in a straight line.

Find the point corresponding to the position of '300', which is the initial value of the desired brightness of the target light (PURPOSE_LIGHT) on the connected straight line, and the graph is between '100' and '400', and the reference driving pulse corresponding to the found point. When the duty ratio 'Rref.purpose' of (REF_DR_PUL)-in the graph is between 'Rref.1' and 'Rref.2'-is found, the value of the desired light in the red LED included in the reference block 100 The duty ratio of the reference driving pulse REF_DR_PUL capable of generating '300', which is the initial value of the luminance PURPOSE_LIGHT, becomes.

That is, even when the initial value of the desired luminance of the light PURPOSE_LIGHT is not present in the look-up table CD_TABLE of the second storage unit 150, the value may be interpolated and found.

For reference, the interpolation method illustrated in FIG. 3 is a linear interpolation method, which is a simple method among interpolation methods as a method of connecting data already determined with a straight line and finding data to interpolate. Attaching the graph using the linear interpolation method to the embodiments is merely for convenience of description, and other interpolation methods may be used when actually applied to the LED backlight system.

In the same manner as described above, each LED block 100 and 110 <0: may be irrespective of whether the desired luminance of the light PURPOSE_LIGHT is presented in the look-up table CD_TABLE of the second storage unit 150 or not. N>), the duty ratio of each of the LED driving pulses REF_DR_PUL and ARD_DR_PUL <0: N> for generating the desired luminance of the light PURPOSE_LIGHT can be determined.

In response to the duty ratio of each of the LED driving pulses REF_DR_PUL and ARD_DR_PUL <0: N> thus determined, each of the LED driving units 120 and 130 <0: N> is assigned to each LED block 100 and 110 <0: N. >), The initial value of the luminance of the desired light PURPOSE_LIGHT is generated 210 in each of the LED blocks 100 and 110 <0: N>, thereby terminating the initial operation.

Then, at the timing at which the operation after the initial operation is started, both 'yes' and 'no' for 'does the luminance value of the intended light vary?' According to the luminance (OUT_LIGHT) value of the externally applied light. Can come out.

That is, 'yes' is selected if the luminance of the target light PURPOSE_LIGHT is changed due to the luminance of the light OUT_LIGHT applied from the outside, but no is selected.

In this case, when 'Yes' is selected, the method for generating the initial value of the luminance PURPOSE_LIGHT of the above-described desired light in each of the LED blocks 100 and 110 <0: N> is almost the same. The reason is that when the luminance OUT_LIGHT of the externally applied light is different from the initial value of the luminance PURPOSE_LIGHT of the desired light, the target luminance of light PURPOSE_LIGHT is the luminance of the external light OUT_LIGHT. Because it is replaced. Therefore, when the luminance OUT_LIGHT of the light applied from the outside is different from the target luminance PURPOSE_LIGHT of the operation after the initial operation, the luminance of the target light is determined to be the value of the luminance OUT_LIGHT applied from the outside. Recognized as a value of the "PURPOSE_LIGHT" so that each LED driver 120, 130 <0: N> can generate the desired brightness (PURPOSE_LIGHT).

That is, each of the LED driving pulses REF_DR_PUL and ARD_DR_PUL <0 for generating a desired luminance of light PURPOSE_LIGHT on the basis of the look-up table CD_TABLE of the second storage unit 150 whose value is predetermined. N>) is used to interpolate the duty ratio.

The method of interpolating the duty ratio of each of the LED driving pulses REF_DR_PUL and ARD_DR_PUL <0: N> on the basis of the look-up table CD_TABLE of the second storage unit 150 having a predetermined value is known in the art. Compared to the feedback method using the color sensor described in the above, the steps for determining the value of each LED driving pulse (REF_DR_PUL, ARD_DR_PUL <0: N>) are simple, so each LED driving pulse (REF_DR_PUL, ARD_DR_PUL < 0: N>) to determine the duty ratio.

Therefore, even if the luminance OUT_LIGHT of the externally applied light, such as a dimming operation, is required to be changed at least 60 times to 120 times per second, it can be processed without any problem.

In detail, the case in which 'no' is selected will be described in detail. Based on the data LC_DATA of the first storage unit 140, the detected light amount LIGHT_SENS is the color coordinate PURPOSE_COLOR and the luminance of the light. The operation 220 outputting the adjusted reference drive pulse REF_DR_PUL by adjusting the duty ratio of the reference drive pulse REF_DR_PUL to match the PURPOSE_LIGHT is a feedback method using a color sensor described in the prior art, and is divided into two stages. It can be seen that.

First, an operation of calculating color coordinates and luminance of light corresponding to the detected light amount LIGHT_SENS based on the data LC_DATA of the first storage unit 140 is necessary. The detected light amount LIGHT_SENS is determined in the reference block 100. This is because the amount of light generated is the value detected by the color sensor. That is, since the detected amount of light LIGHT_SENS output from the color sensor is merely an electrical signal corresponding to the amount of light generated from the reference block 100, a mathematical calculation is required to convert it into light defined by color coordinates and luminance. .

Therefore, in the reference block 100 using the data LC_DATA of the first storage unit 140 in which the color coordinates and luminance values of the light, which are contrasted with the light having a predetermined amount of light, are defined based on the CIE standard color coordinate system. Find out the color coordinates and luminance of the generated light.

For reference, the reference block 100 may be configured by using the data LC_DATA of the first storage unit 140 in which the color coordinates and luminance values of light, which are contrasted with light having a plurality of predetermined amounts of light, are defined based on the CIE standard color coordinate system. Since the method for determining the color coordinates and luminance of the light generated by the known technique is not described in detail here.

Thereafter, the color coordinates and luminance of light generated in the reference block 100 are compared with the target color coordinates PURPOSE_COLOR and luminance PURPOSE_LIGHT, and the difference is calculated, and the duty ratio of the reference driving pulse REF_DR_PUL is calculated by the calculated difference. The compensating operation is an operation for generating light having the desired color coordinates PURPOSE_COLOR and luminance PURPOSE_LIGHT in the reference block 100.

That is, the reference driving pulse REF_DR_PUL for driving the reference block 100 by a portion where the color coordinates and luminance of the light generated in the current reference block 100 do not coincide with the target color coordinates PURPOSE_COLOR and luminance PURPOSE_LIGHT. By compensating for the duty ratio, the light having the desired color coordinates PURPOSE_COLOR and luminance PURPOSE_LIGHT can be generated in the reference block 100.

When the duty ratio of the reference driving pulse REF_DR_PUL capable of generating light having the desired color coordinates PURPOSE_COLOR and luminance PURPOSE_LIGHT in the reference block 100 is compensated, the look-up table of the second storage unit is compensated. An operation 230 of interpolating the duty ratios of the peripheral driving pulses ARD_DR_PUL <0: N> corresponding to the duty ratios of the reference driving pulses REF_DR_PUL compensated with respect to (CD_TABLE) is performed. The operation 230 in which the duty ratio of the peripheral driving pulse ARD_DR_PUL <0: N> is interpolated will be described in detail as follows.

First, the look-up table CD_TABLE of the second storage unit is the same as that shown in Table 1.

Therefore, the duty ratio of the reference driving pulse REF_DR_PUL whose values are determined corresponding to the predetermined color coordinates' x, y 'and the plurality of predetermined luminance '50, 100, 400' (Rref. 0, Gref. 0, Bref). .0), (Rref.1, Gref.1, Bref.1), (Rref.2, Gref.2, Bref.2) 'and the duty ratio of each peripheral drive pulse (ARD_DR_PUL <0: N>) (R0.0, G0.0, B0.0), (R0.1, G0.1, B0.1), (R0.2, G0.2, B0.2),... , (RN.0, GN.0, BN.0), (RN.1, GN.1, BN.1), (RN.2, GN.2, BN.2) 'are listed.

In addition, the reference driving pulse is performed such that the detected light amount LIGHT_SENS matches the target color coordinate PURPOSE_COLOR and the target brightness luminance PURPOSE_LIGHT based on the data LC_DATA of the first storage unit 140 described above. The reference block 100 generates light having a desired luminance (PURPOSE_LIGHT) in the reference block 100 by adjusting the duty ratio of (REF_DR_PUL) to output the adjusted reference drive pulse REF_DR_PUL. The duty ratio of the reference drive pulse REF_DR_PUL can be determined.

At this time, the duty ratio of the reference drive pulse REF_DR_PUL, which can generate light having the desired luminance PURPOSE_LIGHT in the reference block 100, is the reference drive pulse REF_DR_PUL listed in the lookup table CD_TABLE of the second storage unit. ), Any one of the duty ratio '(Rref.0, Gref.0, Bref.0), (Rref.1, Gref.1, Bref.1), (Rref.2, Gref.2, Bref.2)' When the value of is matched, the duty ratio '(R0.0, G0.0, B0.0) of the peripheral drive pulse (ARD_DR_PUL <0: N>) listed in the lookup table (CD_TABLE) of the second storage unit, (R0.1, G0.1, B0.1), (R0.2, G0.2, B0.2),... , (RN.0, GN.0, BN.0), (RN.1, GN.1, BN.1), (RN.2, GN.2, BN.2) 'matching reference drive pulse ( The duty ratio of the peripheral driving pulse ARD_DR_PUL <0: N> corresponding to the duty ratio of REF_DR_PUL can generate light having the desired luminance PURPOSE_LIGHT in each peripheral block 110 <0: N>. Value.

Here, the duty ratio of the reference drive pulse REF_DR_PUL that can generate light having the desired luminance PURPOSE_LIGHT in the reference block 100 and the reference drive pulse listed in the look-up table CD_TABLE of the second storage unit. When comparing the duty ratios of (REF_DR_PUL) '(Rref.0, Gref.0, Bref.0), (Rref.1, Gref.1, Bref.1), (Rref.2, Gref.2, Bref.2) Compare red, green, and blue separately. That is, the duty ratio of the reference driving pulse REF_DR_PUL whose duty ratio of the reference driving pulse REF_DR_PUL corresponding to the red component of the light having the desired luminance PURPOSE_LIGHT is listed in the lookup table CD_TABLE is' Rref.0, Compares with Rref.1 and Rref.2 ', and if there is a matching value in the comparison result, the duty ratio' R0 of the peripheral drive pulse (ARD_DR_PUL <0: N>) listed in the lookup table (CD_TABLE) Find the corresponding value among .0, R0.1, R0.2, RN.0, RN.1, and RN.2 '.

Of course, the duty ratio of the reference drive pulse REF_DR_PUL, which can generate light having the desired luminance PURPOSE_LIGHT in the reference block 100, is the reference drive pulse REF_DR_PUL listed in the look-up table CD_TABLE of the second storage unit. ), Any one of the duty ratio '(Rref.0, Gref.0, Bref.0), (Rref.1, Gref.1, Bref.1), (Rref.2, Gref.2, Bref.2)' It may happen that does not match the value of.

At this time, the peripheral driving pulse ARD_DR_PUL <0: N, which can generate light having the desired luminance (PURPOSE_LIGHT) in each peripheral block 110 <0: N>, using an interpolation method that predicts the value as follows. Calculate the duty ratio of>).

FIG. 4 is a graph illustrating interpolating duty ratios of peripheral driving pulses corresponding to duty ratios of reference driving pulses according to an exemplary embodiment of the present invention.

Referring to FIG. 4, as illustrated above, the duty ratio of the reference driving pulse REF_DR_PUL, which may generate light having the desired luminance PURPOSE_LIGHT in the reference block 100, is the look-up table CD_TABLE of the second storage unit. Duty ratios of reference drive pulses (REF_DR_PUL) '(Rref.0, Gref.0, Bref.0), (Rref.1, Gref.1, Bref.1) and (Rref.2, Gref. 2, Bref. 2) 'even if the value does not match, it can be seen that the value is predicted through interpolation.

Specifically, the graph shown in FIG. 4 shows the duty ratio 'Rref.0,' of the reference driving pulse REF_DR_PUL for driving the red LED included in the reference block 100 shown in the look-up table CD_TABLE of the second storage unit. Red LED included in each peripheral block 110 <0: N> corresponding to the duty ratios Rref.0, Rref.1, and Rref.2 of Rref.1, Rref.2 'and the reference drive pulse REF_DR_PUL. The duty ratio 'R0.0, R0.1, R0.2' of the 0th peripheral drive pulse (ARD_DR_PUL <0>) is displayed among the peripheral drive pulses (ARD_DR_PUL <0: N>) for driving Is connected in a straight line.

Position of the duty ratio 'Rref.purpose' of the reference drive pulse (REF_DR_PUL) that can generate a light having a desired luminance (PURPOSE_LIGHT) in the red LED included in the reference block 100 in a straight line connected in this way-in the graph 'Rref' .1 'and' Rref.2 '-find the point corresponding to the duty ratio of the 0th peripheral drive pulse (ARD_DR_PUL <0>) corresponding to the found point' R0.purpose '-in the graph' R0. Is between 1 'and' R0.2 '-If the value is found, the value is the desired luminance in the red LED included in the 0th peripheral block (110 <0>) of each peripheral block (110 <0: N>). The duty ratio of the peripheral driving pulses ARD_DR_PUL <0: N>, which can generate light having (PURPOSE_LIGHT), is obtained.

That is, even when the duty ratio of the reference driving pulse REF_DR_PUL that can generate light having the desired luminance PURPOSE_LIGHT in the reference block 100 is not present in the look-up table CD_TABLE of the second storage unit, the value is set. Can be found by interpolation.

Such an interpolation method, in addition to the values of the respective zero peripheral drive pulses ARD_DR_PUL <0> for driving the red LEDs illustrated, the respective zeroth to Nth peripheral drive pulses for driving the red, green, and blue LEDs. Can also be used to interpolate the value of (ARD_DR_PUL <0: N>).

The duty ratio of the reference drive pulse REF_DR_PUL, which can generate light having the desired luminance PURPOSE_LIGHT in the reference block 100 by the above-described method, is presented in the look-up table CD_TABLE of the second storage unit. It is possible to determine the duty ratio of each peripheral drive pulse ARD_DR_PUL <0: N> for generating the light having the desired luminance (PURPOSE_LIGHT) in each peripheral block 110 <0: N> regardless of the case. have.

In response to the duty ratio of each of the LED driving pulses REF_DR_PUL and ARD_DR_PUL <0: N>, the LED driving units 120 and 130 <0: N> are configured to have respective LED blocks 100 and 110 <0: N. >), The light with the desired color coordinates (PURPOSE_COLOR) and luminance (PURPOSE_LIGHT) is generated 240 in each LED block (100, 110 <0: N>), so the operation after the initial operation is completed once. do. After that, the operation after the initial operation is continuously repeated according to the luminance OUT_LIGHT of the external light.

As described above, when the embodiment of the present invention is applied, a plurality of LED arrays included in the LED backlight are grouped by a predetermined number-each group has a red LED array, a blue LED array, and a green LED array uniformly. Included-divided into multiple LED blocks-including one reference block and multiple peripheral blocks-and a plurality of drive pulses for controlling each LED block-includes a reference drive pulse and a plurality of peripheral drive pulses Independently controlling the duty ratio of-allows multiple LED blocks to produce light with the same color coordinates and brightness, despite a 15% to 20% performance difference between each LED block. That is, light having the same color coordinates and luminance may be generated in the entire area of the LED backlight.

Also, when the luminance of the desired light is inputted, the duty ratio value of each driving pulse corresponding to the luminance of the plurality of predetermined lights is determined according to the luminance of the desired light based on a look-up table in which the predetermined value is determined. By using a method of adjusting the duty ratio of the driving pulse of the LED, it is possible to generate the desired light in each LED block much faster than the feedback method using the color sensor.

As a result, it is possible to enable dimming control of the LED backlight requiring the brightness to change at least 60 to 120 times per second.

The present invention described above is not limited to the above-described embodiments and drawings, and it is common in the art that various substitutions, modifications, and changes can be made without departing from the technical spirit of the present invention. It will be apparent to those who have knowledge.

For example, in the above-described embodiment, only the linear interpolation method is used, but the present invention includes the use of other known interpolation methods in addition to the linear interpolation method.

1 is a block diagram illustrating an LED backlight system according to an embodiment of the present invention.

2 is a flowchart illustrating the operation of the LED backlight system according to the embodiment of the present invention shown in FIG.

3 is a graph illustrating interpolation of driving pulses corresponding to luminance according to an exemplary embodiment of the present invention.

FIG. 4 is a graph illustrating interpolating duty ratios of peripheral driving pulses corresponding to duty ratios of reference driving pulses according to an exemplary embodiment of the present invention.

* Explanation of symbols for main parts of the drawings

100: reference block 110 <0: N>: a number of peripheral blocks

120: reference driving unit 130 <0: N>: a plurality of peripheral driving unit

140: first storage unit 150: second storage unit

160: detection unit 170: first duty ratio interpolation unit

180: second duty ratio interpolation unit 190: third storage unit

195: pulse transfer unit

Claims (14)

A plurality of LED blocks including one reference block and a plurality of peripheral blocks; LED for driving each LED block with a driving force according to the duty ratio of the LED driving pulse corresponding to each LED block, including the reference driving pulse corresponding to the reference block and the peripheral driving pulse corresponding to each peripheral block. Drive means; First storage means for storing data about color coordinates and luminance of light in contrast to light having a plurality of predetermined amounts of light based on a CIE standard color coordinate system; Second storage means for storing a look-up table for the duty ratio of each LED drive pulse for each LED block to generate light having a predetermined plurality of brightnesses; Sensing means for sensing an amount of light generated by the reference block and outputting a detected amount of light; Interpolating the duty ratio of the reference driving pulse in response to the desired brightness of the light based on the look-up table of the second storage means, or detecting a color coordinate of the desired light based on the data of the first storage means; First duty ratio interpolation means for adjusting a duty ratio of the reference driving pulse to match luminance; Interpolating the duty ratio of each peripheral driving pulse in response to the desired brightness of the light based on the look up table of the second storage means, or interpolating the first duty ratio based on the look up table of the second storage means. Second duty ratio interpolation means for interpolating the duty ratio of each peripheral drive pulse corresponding to the duty ratio of the output pulse of the means; LED backlight system having a. The method of claim 1, And a pulse transmitting means for transmitting output pulses of the first and second duty ratio interpolation means to the LED driving means through a serial bus. The method of claim 1, And a third storage means for storing information about the color coordinates of the desired light and the brightness of the desired light. The method of claim 3, The color coordinates of the target light and the brightness of the target light, Has a predetermined initial value applied in the initial operation, In the operation after the initial operation, the LED backlight system, characterized in that it has a color coordinate and the luminance value of the light applied from the outside. The method of claim 4, wherein The first duty ratio interpolation means, If the luminance of the light applied from the outside is different from the luminance of the target light stored in the third storage means, the reference driving is performed in response to the luminance of the target light based on the look-up table of the second storage means. An LED backlight system comprising interpolating the duty ratio of pulses. The method of claim 4, wherein The first duty ratio interpolation means, If the luminance of the light applied from the outside is the same as the luminance of the target light stored in the third storage means or the luminance of the light is not input from the outside, the amount of detected light based on the data of the first storage means LED backlight system, characterized in that to interpolate the duty ratio of the reference drive pulse to match the color coordinates and luminance of the desired light. The method of claim 4, wherein The second duty ratio interpolation means, When the brightness of the light applied from the outside is different from the brightness of the target light stored in the third storage means, the respective light sources correspond to the brightness of the target light based on the look-up table of the second storage means. LED backlight system characterized by interpolating the duty ratio of the peripheral driving pulses. The method of claim 4, wherein The second duty ratio interpolation means, If the luminance of the light applied from the outside is the same as the luminance of the desired light stored in the third storage means or if the luminance of light is not input from the outside, the second display means based on the lookup table of the second storage means. And a duty ratio of each peripheral driving pulse corresponding to the duty ratio of the output pulse of the one duty ratio interpolation means. The method according to any one of claims 3 to 8, The data of the first storage means, the look-up table of the second storage means and the information about the color coordinates and luminance of the desired light of the third storage means are stored in the internal nonvolatile memory device. . Driving a plurality of LED blocks-including a reference block and a plurality of peripheral blocks-with a driving force according to the duty ratio of the plurality of LED driving pulses-including one reference driving pulse and a plurality of peripheral driving pulses. ; Creating a look up table for the duty ratio of each LED drive pulse for each LED block to generate light having a predetermined plurality of brightnesses; Generating data about color coordinates and luminance of light compared to light having a plurality of predetermined amounts of light based on a CIE standard color coordinate system; Interpolating the duty ratio of each of the LED driving pulses corresponding to the desired brightness of the light based on the lookup table for the duty ratio; Sensing a light amount of light generated in the reference block and outputting a detected light amount; Outputting an adjusted reference driving pulse by adjusting a duty ratio of the reference driving pulse so that the detected light quantity matches the color coordinate and luminance of a desired light based on the data about the color coordinate and the luminance; Interpolating the duty ratio of each peripheral drive pulse corresponding to the duty ratio of the adjusted reference drive pulse based on the look-up table for the duty ratio Method of operation of the LED backlight system comprising a. The method of claim 10, Causing the color coordinates of the target light and the luminance of the target light to have a predetermined initial value in an initial operation; And And operating the color coordinates of the target light and the luminance of the target light in the operation after the initial operation to have the color coordinates and luminance values of the light applied from the outside. The method of claim 11, Interpolating the duty ratio of each LED driving pulse, Performed when the luminance value of the externally applied light in the first operation or the initial value set in the initial operation is different from the luminance value of the externally applied light in the second operation, which is performed later than the first operation. Method of operation of the LED backlight system characterized in that. The method of claim 11, Interpolating the duty ratio of each LED driving pulse, Performed when the luminance value of the externally applied light in the first operation or the initial value set in the initial operation is equal to the luminance value of the externally applied light in the second operation, which is performed later than the first operation. Method of operation of the LED backlight system, characterized in that not. The method of claim 11, The step of outputting the sensed light amount, interpolating the duty ratio of the reference drive pulse and interpolating the duty ratio of the peripheral drive pulse, Performed when the luminance value of the externally applied light in the first operation or the initial value set in the initial operation is equal to the luminance value of the externally applied light in the second operation, which is performed later than the first operation. Method of operation of the LED backlight system characterized in that.

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