KR100694801B1 - Picture screen compensation apparatus for lcd backlight unit equipped with led - Google Patents

Abstract

An image compensation apparatus using an LED(Light Emitting Diode) for an LCD(Liquid Crystal Display) backlight unit is provided to obtain uniform brightness on the overall LCD screen by compensating for the brightness difference of an LED module by correcting the duty ratio of a PWM signal. An image compensation apparatus for an LCD backlight unit includes an LED driver(120), a sensor(130), a backlight controller(140), and a PWM(Pulse Width Modulation) signal adjusting unit(150). The LED driver selectively supplies LED driving currents to plural LED array units according to RGB LED driving PWM signals input from the outside. The sensor detects the color and brightness of the LEDs in the LED array unit. The backlight controller generates RGB LED driving PWM reference signals for turning on the RGB LEDs corresponding to the color and brightness detected by the sensor. When the PWM reference signal is inputted from the backlight controller, the PWM signal adjusting unit delays the PWM reference signal by a predetermined time and outputs the result to the LED driver as the RGB driving PWM signal.

Description

Picture screen compensation apparatus for LCD backlight unit equipped with LED}

1 is a view for explaining the brightness control device of the LCD backlight unit using the LED according to the prior art,

2 is a view for explaining the image quality compensation device of the LCD backlight unit using the LED according to the present invention;

3 is a pulse waveform diagram of a PWM signal output to the LED array unit of FIG.

4 is a pulse waveform diagram of a corrected PWM signal output to the LED array unit of FIG. 2.

*** Explanation of symbols on main parts of drawing ***

110: LED array unit

120: LED driver

130 sensor

140: backlight control unit

150: PWM signal control unit

160: storage unit

The present invention relates to a device for compensating image quality of an LCD backlight unit using LEDs.

In particular, it delays the phase of the PWM signal so that noise does not occur in the LED module, and compensates the luminance deviation by correcting the duty ratio of the PWM signal to improve the image quality of the LCD backlight unit. It is about.

Compared with the existing light source, the energy saving effect is excellent and almost semi-permanent. Therefore, the application of the market is spreading throughout the industry as the luminance and price problems, which were the limitations of the LED which is being spotlighted as the next generation light source, have been greatly improved recently.

LEDs are rapidly improving brightness due to the rapid development of related technologies and raw material technologies, and the price is expected to be similar to the existing light sources such as incandescent lamps, fluorescent lamps and CCFL lamps in the next few years due to economies of scale due to mass production system. have.

LEDs have been used mainly as a light source for small LCD backlights such as mobile phones, but recently, LEDs with high brightness and high power have been introduced one by one, and have a color reproducibility compared to that of the Cold Cathode Fluorescent Lamp (CCFL). Since it has been greatly improved, studies are being actively conducted to expand the light source of medium and large LCD backlights.

1 is a view for explaining a brightness control device for adjusting the brightness in the LCD backlight unit using the LED module according to the prior art.

As shown in FIG. 1, a plurality of LED array units 10 and on or off signals are turned on or off in response to PWM (abbreviation of pulse width modulation) signals of the backlight controller 16 to be described later. LED driving unit 12 to emit light or light by supplying or blocking a driving current to the LED of the LED array unit 10 of the LED array, and a sensor 14 for detecting and outputting the chromaticity and luminance of the LED array unit 10 in real time. And the chromaticity and luminance detection signals of the LED array unit 10 output from the sensor 14, and adjust the duty ratio of the PWM signal by the chromaticity and luminance detection signals to adjust the duty ratio of the plurality of LED array units ( And a backlight controller 16 for outputting to the controller 10.

The sensor 14 is a color sensor.

Referring to the operation of the brightness control device of the LCD backlight unit using the LED module according to the prior art configured as described above are as follows.

First, the backlight controller 16 outputs a PWM signal to the LED driver 12 to adjust the luminance of the plurality of LED array units 10, and the LED driver 12 is turned on or off so that the LED array unit 10 is turned on. Current to be supplied or interrupted. The reason for applying the LED array unit 10 in which a plurality of LEDs are arranged as described above is that the light emitting surface of the LED is small, as is widely known.

When the plurality of LED array units 10 emit light by the PWM signal of the backlight controller 16 as described above, the sensor 14 detects the chromaticity and the luminance of the plurality of LED array units 10. The chromaticity and luminance signals sensed by the sensor 14 are input to the backlight controller 16, and the backlight controller 16 outputs to the plurality of LED array units 10 in response to the chromaticity and luminance signals. The duty ratio of the PWM signal is adjusted, and the PWM signal whose duty ratio is adjusted is output to the LED array unit 10 again.

However, since the brightness control device of the LCD backlight unit using the conventional LED module allows the PWM signal to be applied to all the LED arrays at the same time, a large amount of current is applied when the LED is large, and the large amount of current corresponds to the PWM frequency. There is a problem that noise is generated because it is repeatedly applied.

In addition, there is a problem that the image quality of the LCD is degraded due to the noise.

In addition, in the luminance control device of the LCD backlight unit using a conventional LED module, the light generated from the LED passes through the diffusion filter, the amount of light that appears through the LCD due to factors such as the position of the LED light source, the performance deviation of the LED light source, etc. There is a problem that this is not uniform.

The present invention has been made in accordance with the necessity of the prior art as described above, and an object of the present invention is to delay the phase of the PWM signal so that noise does not occur in the LED module, and to compensate for the luminance deviation by correcting the duty ratio of the PWM signal. The present invention provides a device for compensating an image quality of an LCD backlight unit using LEDs to improve the image quality of an LCD by calibrating.

One embodiment of the present invention proposed to solve the above technical problem, in the image quality compensation device of the LCD backlight unit using the LED having a plurality of LED array unit, a plurality of LED array in response to the PWM signal input from the outside LED driver for supplying or blocking the LED driving current to the couple; A sensor for sensing and feeding back the chromaticity and luminance of the LEDs forming the plurality of LED array units; A backlight controller which generates and outputs a PWM reference signal for driving an R / G / B LED for blinking an RGB LED of the LED array unit in response to a chromaticity and luminance detection signal of the LED output from the sensor; And a PWM signal controller for delaying the PWM reference signal by a predetermined delay time t when the PWM reference signal is input from the backlight controller and outputting the R / G / B driving PWM signal to the LED driver. Characterized in that the configuration.

Hereinafter, an image quality compensating apparatus of an LCD backlight unit using LEDs will be described in detail with reference to the accompanying drawings.

The image quality compensation device of the LCD backlight unit using the LED according to the present invention, as shown in Figure 2, the LED array unit 110 consisting of a plurality of RGB LED, PWM signal control unit 150 to be described later LED driver 120 to emit light or light by supplying or blocking a driving current to the R / G / B LED constituting the plurality of LED array 110 in response to the PWM signal for driving the R / G / B input through ), A sensor 130 that senses the chromaticity and luminance of the LEDs constituting the plurality of LED array units 110 and feeds back to the backlight controller 140 to be described later, and the chromaticity of the LEDs output from the sensor 130; A backlight controller 140 for generating and outputting an R / G / B driving PWM reference signal for blinking the RGB LEDs of the LED array unit 110 in response to the luminance detection signal, and the R / R / G when PWM reference signal for G / B driving is input A PWM signal controller 150 for delaying the PWM reference signal for / B driving by a predetermined delay time t and outputting the R / G / B driving PWM signal, and the delay time and duty ratio The storage unit 160 stores information in the form of a lookup table.

In this case, the duty ratio information is composed of the corresponding R / G / B LED information and the duty ratio of the PWM signal.

In this case, the storage unit 160 is an EEPROM.

The delay time t and the duty ratio information stored in the storage 160 may be stored through the test device 200 connected to the backlight controller 140 by serial communication. That is, the test apparatus 200 outputs a test signal to the LED array unit 110 through the backlight controller 140 and receives a result signal corresponding to the test signal from the backlight controller 140 to receive the LED array. The operation state of the unit 110 is grasped to find the optimal duty ratio of the PWM signal for each of the delay time t and the R / G / B LEDs and stored in the storage unit 160. Accordingly, the LED array unit 110 is delayed by the delay time (t) by the PWM signal adjusting unit 150, the noise is removed by receiving the R / G / B driving PWM signal corrected to the optimum duty ratio, Luminance deviation is corrected to provide improved LCD image quality.

The PWM signal adjusting unit 150 delays the R LED driving PWM reference signal by the delay time t and outputs the first PWM signal when the R LED driving PWM reference signal is input, and outputs the first PWM signal. The PWM signal is delayed by the delay time t and output as the second PWM signal. That is, as shown in FIG. 3, the R LED driving PWM signal is delayed by a delay time t from the R LED driving PWM signal output to the LED driver 120 immediately before the LED driver 120. Will be output as

And, as shown in Figure 3, the PWM signal control unit 150, when the G LED driving PWM reference signal (B) is input to the G LED driving PWM reference signal for the R LED driving The R LED driving PWM signal, which is output last of the PWM signals, is output, delayed by the delay time t, and then output as the first PWM signal for driving G LED. The first PWM signal for driving the G LED is delayed by the delay time t and output as the second PWM signal for driving the G LED.

And, as shown in Figure 3, the PWM signal control unit 150, when the B LED driving PWM reference signal (C) is input, the B LED driving PWM reference signal for the G LED driving The G LED driving PWM signal, which is output last of the PWM signals, is output, delayed by the delay time t, and then output as the first PWM signal for driving B LEDs. The first PWM signal for driving the B LEDs is delayed by the delay time t and output as the second PWM signal for driving the B LEDs.

Meanwhile, as shown in FIG. 3, the PWM signal controller 150 stores the R / G / B driving PWM signal delayed by a delay time t, as shown in FIG. 4. ) Reads the duty ratio information stored in the), corrects only the duty ratio of the corresponding PWM signal, and outputs the duty ratio information to the LED driver 120.

Referring to the operation of the image quality compensation device of the LCD backlight unit using the LED configured as described above are as follows.

When the driving current is supplied to the LED array unit 110 and the corresponding LED is driven, the sensor 130 measures the chromaticity and luminance of the LED in real time as shown in FIGS. 2 to 4. Output the feedback to). Then, the backlight controller 140 generates a PWM reference signal (A) (B) (C) for driving the R / G / B in response to the chromaticity and luminance detection signal of the LED input from the sensor 130 to adjust the PWM signal. Output to 150.

That is, since the LED array unit 110 generates white light by combining the LEDs of RED, BLUE, and GREEN, the backlight controller 140 uses the color information input through the sensor 130 to control the R, G, and B LEDs. As shown in FIG. 3, the PWM reference control unit 150 generates PWM reference signals A, B, and C for driving R / G / B so that the white light is always radiated by individually adjusting the duty ratio. )

Then, the PWM signal controller 150 reads the delay time t stored in the storage 160 and attaches the input R driving PWM reference signal A to the delay time as shown in FIG. 3. The R LED driving PWM signals 1 to 9 sequentially delayed by t) are output to the LED driver 120. At this time, the PWM signal controller 150 checks whether the duty ratio information is stored in addition to the delay time t in the storage 160 and reads the duty ratio information when the duty ratio information is stored, thereby delaying R driving. The duty ratio of the corresponding PWM signal among the PWM signals 1 to 9 is corrected to be output to the LED driver 120.

In addition, the backlight control unit 140 increases or decreases the luminance ratio of the entire RGB in order to adjust the luminance of the LED array unit 110. Then, the plurality of R LEDs constituting the R LED array unit 110 is turned on or off with a very short time difference.

Meanwhile, the PWM signal controller 150 also drives the G LED in the same manner as that of driving the R LED as described above. When only the PWM signal controller 150 inputs the G LED driving PWM reference signal (B of FIG. 3) from the backlight controller 140, the PWM signal controller 150 controls the G LED driving PWM reference signal (FIG. 3) B) is delayed by the delay time (t) from the rising edge output time of the R LED driving PWM signal outputted last among the R LED driving PWM signals, and the LED driving unit as the first PWM signal for driving the G LED. To be entered at 120.

Similarly to the case of the G LED, the plurality of B LEDs, the PWM signal controller 150 is a PWM signal controller (C in FIG. 3) when the B LED driving PWM reference signal (C of FIG. 3) is input from the backlight controller 140, 150) the B LED driving PWM reference signal (C of FIG. 3) is set by the delay time t from the rising edge output time of the G LED driving PWM signal which is output to the last of the G LED driving PWM signals. The delay is input to the LED driver 120 as the first PWM signal for driving the B LED.

Meanwhile, the PWM signal controller 150 receives the R / G / B driving PWM reference signals A, B, and C from the backlight controller 140 as described above, and uses the PWM reference signals for a delay time. When outputting the delayed R / G / B driving PWM signals 1 to 9 to the LED driver 120, it is determined whether the duty ratio information is stored in addition to the delay time t in the storage unit 160. do. As a result of the determination, when the duty ratio information is stored, the PWM signal controller 150 reads the duty ratio information from the storage unit 160 and checks which LED driving PWM signal needs to be corrected.

According to the check result, the duty ratio of the PWM signal delayed by the delay time t is corrected by one step as shown in FIG. 4 and output to the corresponding LED driver 120.

The present invention is not limited to the above embodiments, and various modifications and changes can be made by those skilled in the art, which are included in the spirit and scope of the present invention included in the appended claims.

The present invention having the above-described configuration, operation, and preferred embodiments adjusts a PWM signal to be driven at a time difference with respect to a plurality of LEDs of a plurality of LED array units, so that a large amount of current is repeatedly made in response to the PWM frequency. Even when applied, noise does not occur, so that the LCD image quality can be prevented from being degraded.

In addition, the present invention has the effect of correcting the luminance deviation of the LED module by correcting the duty ratio of the PWM signal for driving the plurality of LEDs, thereby making the brightness of the entire LCD screen uniform.

Claims (11)

In the image quality compensation device of the LCD backlight unit using the LED having a plurality of LED array unit, An LED driver for supplying or blocking an LED driving current to a plurality of LED array units in response to a PWM signal for driving an R / G / B LED; A sensor for sensing and feeding back the chromaticity and luminance of the LEDs constituting the plurality of LED arrays; A backlight controller which generates and outputs a PWM reference signal for driving an R / G / B LED for blinking an RGB LED of the LED array unit in response to a chromaticity and luminance detection signal of the LED output from the sensor; And When the PWM reference signal is input from the backlight control unit, the PWM signal control unit delays the PWM reference signal by a predetermined delay time t and outputs the R / G / B driving PWM signal to the LED driver. Image quality compensation device of the LCD backlight unit using an LED, characterized in that the configuration, including. The method of claim 1, wherein the PWM signal control unit, When the R LED driving PWM reference signal is input, the R LED driving PWM reference signal is delayed by the delay time t to be output as an N-th PWM signal, and the N PWM signal is output to the delay time t. The image quality compensation device of the LCD backlight unit using the LED, characterized in that by delaying the output by the N + 1 PWM signal. The method of claim 2, wherein the PWM signal control unit, When the G LED driving PWM reference signal is input, the G LED driving PWM reference signal is delayed by the delay time t from the rising edge output time of the N + 1 PWM signal to be output as the M th PWM signal. And delaying the M-th PWM signal by the delay time (t) and outputting the M-th PWM signal as the M + 1 PWM signal. The method of claim 3, wherein the PWM signal control unit, When the B LED driving PWM reference signal is input, the B LED driving PWM reference signal is delayed by the delay time t from the rising edge output time of the M + 1 PWM signal to be output as the O PWM signal. And delaying the O PWM signal by the delay time (t) to output the O + 1 PWM signal. The method of claim 1, wherein the delay time t is The image quality compensation device of the LCD backlight unit using the LED, characterized in that the stored in the storage unit in the form of a look-up table and outputted at the request of the PWM signal controller. The method of claim 1, wherein the delay time t is The image quality compensation device of the LCD backlight unit using the LED, which is input from the test device connected by serial communication to the backlight control unit, stored in the storage unit by the backlight control unit and output at the request of the PWM signal control unit. The method of claim 1, wherein the PWM signal control unit, When the R / G / B driving PWM reference signal is input from the backlight controller, the duty ratio information input from the outside is read and the duty ratio of the R / G / B driving PWM signal is corrected and output. Image quality compensation device of LCD backlight unit using LED. The method of claim 7, wherein the duty ratio information, The image quality compensation device of the LCD backlight unit using the LED, characterized in that the stored in the storage unit in the form of a look-up table and outputted at the request of the PWM signal controller. The method of claim 7, wherein the duty ratio information, The image quality compensation device of the LCD backlight unit using the LED, which is input from the test device connected by serial communication to the backlight control unit, stored in the storage unit by the backlight control unit and output at the request of the PWM signal control unit. The method of claim 8 or 9, wherein the duty ratio information, Image quality compensation device of the LCD backlight unit using the LED, characterized in that consisting of the duty information of the LED information and the PWM signal. The method of claim 1, wherein the PWM signal control unit, When the R / G / B LED driving PWM reference signal is input from the backlight controller, the R / G / B LED driving PWM reference signal is delayed by a predetermined delay time (t) to R / G / B. Output as a PWM signal for driving the image quality compensation device of the LCD backlight unit using an LED, characterized in that for reading the duty ratio information input from the outside to correct the duty ratio of the PWM signal for driving R / G / B .

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