KR101314324B1 - FSC mode liquid crystal display driving circuit and driving method thereof - Google Patents

Abstract

The present invention relates to an FSC liquid crystal display driving circuit and a driving method for reducing the power consumption in the operation of the LED driver of the liquid crystal display device using the LED as a backlight, the transmission in the data communication between the timing controller and the LED driver FSC liquid crystal is presented by presenting a driving circuit and its driving method for control data which has a small number of times and performs a communication with a high speed communication interface, and a control data which has a high number of transmissions and a data amount with a low speed communication interface. There is an advantage in reducing power consumption when driving the display device.

Description

FSC mode liquid crystal display driving circuit and driving method thereof

1 is a view for explaining a method of driving a field sequential color mode;

2 is a block diagram illustrating backlight driving in an FSC driving liquid crystal display device;

3 is a block diagram showing the configuration of a drive circuit for an FSC liquid crystal display device according to the present invention;

4 is a flowchart illustrating a method of driving a driving circuit for an FSC liquid crystal display according to the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS FIG.

100: timing control unit 110: control data generation unit

120: first transmission module 130: second transmission module

200: LED driver 210: first receiving module

220: second receiving module 230: LED light emitting control unit

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving method of a driving circuit for a display device. More particularly, the present invention relates to an FSC liquid crystal display driving circuit and a driving method of reducing power consumption in the operation of an LED driving unit of a display device using LED as a backlight.

BACKGROUND ART [0002] Liquid crystal displays (LCDs), which tend to increase the practical use gradually, control a rotation angle of a liquid crystal in a plurality of liquid crystal cells arranged in a matrix form and a liquid crystal cell, respectively, (Backlight unit) is transmitted to a liquid crystal panel provided with a TFT (thin film transistor) for supplying image data for displaying a desired image on the screen.

As a light source used in such a backlight unit, a cold cathode fluorescent lamp (hereinafter referred to as 'CCFL') is mainly used. Such a backlight unit has a trend of miniaturization, thinning, and weight reduction. In accordance with this trend, light emitting diodes (LEDs), which are advantageous in terms of power consumption, weight, and brightness, have been proposed instead of CCFLs used in backlight units.

Through the backlight unit using the LED, the field sequential color (FSC) driving method is proposed to obtain better image quality.

Field sequential color (FSC) driving method drives LEDs of three primary colors (red, green, blue) sequentially without displaying color filters. This is a driving method which can display the mixed color by using the afterimage effect by a human eye.

More specifically, the display time of one frame on the panel is divided into three periods of red, green, and blue, and each backlight is sequentially illuminated with intervals in time.

As shown in FIG. 1, this FSC driving method is divided into three subframes (1 Sub-frame) of red (R), green (G) and blue (B) frame = 5.56 ms).

Each subframe is divided into a data writing time (DW = 1.69 ms) through TFT scanning, a liquid crystal response time (LR = 1.5 ms) according to data writing, and a backlight emitting time (BL = 2.37 ms) The time BL during which the backlight can be turned on is the time excluding the data writing time DW and the liquid crystal response time LR.

Briefly, the FSC driving is performed, in which data input to RGB to the liquid crystal panel is sequentially generated once at the same ratio (R: G: B = 1: 1: 1) within one vertical synchronizing period, and corresponding backlight is applied. The light source of is also synchronized in the same manner so that the red (R) light source, the green (G) light source, and the blue (B) light source are sequentially turned on. In this case, each light source is an LED lamp or a fluorescent lamp, and the red, green and blue light sources are sequentially arranged.

FIG. 2 is a block diagram for explaining backlight driving in an FSC driving type liquid crystal display device, and includes a timing controller 10, an LED driver 20, and an LED backlight 30.

The timing controller 10 includes various data for controlling light emission of the LED backlight 30, for example, correlation control temperature (CCT) tuning current control data (D _CCT ) for each of R, G, and B color LEDs, and The on / off timing control data D _{ON / OFF} of the LEDs are generated and output.

The current control data D _CCT is data for setting a current value applied to each of the R, G, and B color LEDs, and is data that is transmitted only once when the LCD is first driven, and the on / off timing control data ( D _{ON / OFF} ) is data indicating timing of turning on / off each of the R, G, and B color LEDs, and data transmitted at each timing of turning on / off each LED.

The LED driving portion 20 corresponds to the current control data (D _CCT) receiving the current control data (D _CCT) and the on / off timing control data (D _{ON / OFF)} or the like from the timing control unit 10 Outputs an input current for each of the R, G, and B color LEDs, and controls LED on / off according to the on / off timing control data D _{ON / OFF} .

In addition, the timing controller 10 and the LED driver 20 are usually made of an integrated circuit (IC), and thus the data communication method between the timing controller 10 and the LED driver 20 is bidirectional serial communication between integrated circuits. It is performed using the I2C communication protocol which is one of the schemes.

At this time, the current value data (D _CCT ) transmitted through the I2C communication protocol should be transmitted to the LED driver 20 before the LED backlight 30 is driven to emit light, and the data of the current control data (D _CCT ) itself. The data is very large and transmits data using a high-speed interface (I / F) that provides a very high transmission frequency of about 250KHz.

In addition, the on / off timing control data D _{ON / OFF} transmitted to the LED driver 20 after the current control data D _CCT is _notified of the on timing and the off timing of the LED. Since the data, the amount of data is very small compared to the current control data D _CCT . This is because the light emitting time of one LED lamp during one frame driving time is only about 20% of the one frame driving time when the FSC liquid crystal display device is driven, and thus data transmission is unnecessary for the remaining 80% of the time. .

However, the on / off timing control data D _{ON / OFF} is also transmitting data through a very high transmission frequency of about 250 KHz, and thus the current control data D _CCT and the on / off timing control data D _{ON / OFF} ) are all performing data transmission using high-speed interface, so the power consumption of high frequency clock signal generation is very high, which means that the data transmission clock generated by switching operation of switching element is high- Since the speed interface requires more switching in a short time due to its high frequency, it is natural that the power consumption of the switching element is high.

The present invention has been made to solve the above problems, an object of the present invention is to reduce the power consumption by improving the data communication method between the timing control unit and the LED driver for driving the backlight when driving the FSC LCD.

The present invention to achieve the above object,

A control data generator for generating current control data for setting a current value to be applied to each of the plurality of LEDs and on / off timing control data for controlling on / off timing of each of the plurality of LEDs; A timing control unit including a first transmission module for outputting to an external circuit and a second transmission module for outputting the on / off timing control data to an external circuit; A first receiving module receiving the current control data, a second receiving module receiving the on / off timing control data, and a current for each of the plurality of LEDs according to the current control data and the on / off timing control data. A drive circuit for an FSC liquid crystal display device including an LED driver having an LED light emission control unit for supply and on / off timing control is proposed.

The plurality of LEDs are characterized in that the red (R), green (G), blue (B) color LED.

The first transmitting module is a high speed data communication module.

The high speed data communication module is characterized by providing a data transmission clock of 250KHz or more.

The second transmission module is characterized in that to provide a data transmission clock between 180 ~ 270Hz.

Two data transmission lines are formed between the second transmission module and the second reception module.

The on / off timing control data is a binary digital signal.

In addition,

Generating current control data for setting a current value to be applied to each of the plurality of LEDs from a timing controller and on / off timing control data for controlling on / off timing of each of the plurality of LEDs; Transmitting the current control data to the LED driver through a first communication interface at a first timing; Transmitting the on / off timing control data to the LED driver through a second communication interface at a second timing; A driving method of a driving circuit for an FSC liquid crystal display device comprising the step of performing current supply and on / off timing control for each of the plurality of LEDs according to the current control data and on / off timing control data.

The first timing is characterized in that the timing preceding the second timing.

The first communication interface is characterized in that it is operated by the I2C communication protocol.

The first communication interface is characterized in that the high speed data communication interface.

The high speed data communication interface is characterized in that the data transmission is performed at a frequency of 250KHz or more.

The second communication interface is characterized in that the data transmission is performed at a frequency between 180 ~ 270Hz.

The on / off timing control data is transmitted through two data transmission lines.

The on / off timing control data is a binary digital signal.

The digital signal is characterized in that one of 00, 01, 10, 11.

00 corresponds to LED off, 01 corresponds to Red LED on, 10 corresponds to Green LED on, and 11 corresponds to Blue LED on. It is characterized by.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in detail with reference to the accompanying drawings.

3 is a block diagram showing the configuration of a drive circuit for an FSC liquid crystal display device according to the present invention, and is composed of a timing controller 100 and an LED driver 200.

The timing controller 100 receives R, G, and B image data, a sync signal, a main clock signal, and the like from an external device such as a TV or a computer device, and displays the image on the FSC LCD. It generates a plurality of control signals for the control, and further includes a control data generation unit 110, the first transmission module 120, the second transmission module 130 for driving the backlight of the FSC liquid crystal display.

The control data generation unit 110 is a current control data (D _CCT ) for tuning the correlation color temperature (CCT) for each of the R, G, B color LEDs, which are backlights of the FSC liquid crystal display, and on / off timings of the respective LEDs. Generate and output control data (D _{ON / OFF} ). In this case, the current control data D _CCT and the on / off timing control data D _{ON / OFF} may be data input from an external device such as the TV or a computer device.

The current control data D _CCT is data for setting a current value applied to each of the R, G, and B color LEDs, and is data transmitted to the LED driver 200 only once when the LCD is first driven. The on / off timing control data (D _{ON / OFF} ) is binary digital data indicating the timing at which each of the R, G, and B color LEDs are turned on / off. Data transmitted every timing.

The first transmission module 120 transmits the current control data (D _CCT ) generated by the control data generation unit 110 to an external circuit, preferably to the LED driver 200. At this time, the first transmission module 120 is a high-speed (Hi-speed) data communication module, for example, transmits the current control data (D _CCT ) at a data transmission frequency of 250KHz or more.

The second transmission module 130 transmits the on / off timing control data D _{ON / OFF} generated by the control data generation unit 110 to an external circuit, and preferably, the current control data D _CCT . After the transmission of the LED driver 200. In this case, the second transmission module 130 is a data communication module composed of two lines, and provides a very low data transmission frequency between 180 and 270 Hz.

The LED driver 200 receives the current control data D _CCT and the on / off timing control data D _{ON / OFF} transmitted from the timing controller 100 to control the light emission luminance and the light emission timing of the LED.

To this end, the first receiving module 210 receives the current control data (D _CCT ) transmitted at high speed from the first transmitting module 120, the second receiving module 220 is the second transmitting module ( The on / off timing control data D _{ON / OFF} output from 130 is received.

The LED light emission control unit 230 receives the control data input to the first receiving module 210 and the second receiving module 220 to perform light emission control of a plurality of LEDs, the current control data (D _CCT) The current value is applied to each LED by using the AH, and the on / off driving is controlled using the on / off timing control data D _{ON / OFF} .

As described above, the FSC liquid crystal display driving circuit according to the present invention is characterized in that the interface of the current control data (D _CCT ) and the on / off timing control data (D _{ON / OFF} ) transmitted for driving the LED backlight Through the transmission, and can provide the effect of reducing the power consumption through the characteristics of this configuration and the driving method described below, the drive circuit for the FSC liquid crystal display according to the present invention with reference to the flow chart of FIG. The driving method of the will be described.

Referring to the flowchart of FIG. 4, first, the timing controller 100 controls the current control data D _CCT and the on / off timing control data D _{ON /} for each LED control through the control data generator 110. _OFF ) (st1)

The generated control data (D _CCT , D _{ON / OFF} ) is transmitted to the LED driver 200 through the first transmission module 120 and the second transmission module 130, respectively, the LED driver 200 Receives the control data through the first receiving module 210 and the second receiving module 220, respectively.

In this case, the current control data D _CCT transmitted through the first transmitting module 120 and the first receiving module 210 is a power before the power is supplied to the FSC liquid crystal display and each LED is driven to emit light. Transmission is performed at a high data rate of 250KHz or more in one timing, and is preferably transmitted using an I2C communication protocol. (St2)

When the transmission of the current control data (D _CCT ) is completed, the transmission of the on / off timing control data (D _{ON / OFF} ) through the second transmission module 130 and the second receiving module 220 is a second. As the timing is performed, the on / off timing control data D _{ON / OFF} is transmitted at each _{ON / OFF state of} each of the R, G, and B LEDs, and is transmitted at a low data transmission frequency between 180 and 270 Hz. st3) At this time, the first timing at which the current control data D _CCT is started to be transmitted and the second timing at which the on / off timing control data D _{ON / OFF} are transmitted are at different times, and the first timing is different. This point is preceded by the second timing.

In this case, the first transmitting module 120 and the first receiving module 210 may be defined as one first communication interface, and the second transmitting module 130 and the second receiving module 220 may also be defined as one first. Can be defined as 2 communication interfaces. Accordingly, the first and second communication interfaces may be communication interfaces using communication protocols according to the same communication protocol or using communication protocols according to different communication protocols.

Thereafter, the LED light emission control unit 230 performs light emission control for each LED by using the input current control data D _CCT and on / off timing control data D _{ON / OFF} .

In this case, the on / off timing control data D _{ON / OFF} generated by the control data generation unit 110 of the timing controller 100 is binary data and the second transmission module 130 and the second reception module. It is transmitted to the low-speed communication interface via 220 to control the light emission of each LED, preferably divided into four control data to reduce the power consumed during data transmission.

Table 1 below is a preferable example of the on / off timing control data D _{ON / OFF} , and is control data for controlling each of the R, G, and B LEDs constituting the backlight of the FSC liquid crystal display.

LED ON / OFF LED OFF R LED ON G LED ON B LED ON Control data 1 0 0 One One Control data2 0 One 0 One

<Table 1>

Referring to Table 1, in order to control the backlight of the FSC LCD, the control data generating unit 110 controls 00 (LED OFF), 01 (R LED ON), 10 (G LED ON), 11 ( B LED ON) generates and outputs the _{ON / OFF} timing control data (D _{ON / OFF} ) consisting of the control data according to the four cases, such that the LED light emission control unit 230 in the on / off timing control data ( You can control the on / off timing for each of the R, G, and B LEDs according to the input of D _{ON / OFF} ).

In addition, two data transmission lines between the second transmission module 130 and the second reception module 220 may be configured to further reduce power consumption when the control data 1 and the control data 2 are transmitted, respectively.

According to the driving circuit of the FSC liquid crystal display device and the driving method thereof according to the present invention described above, the timing control data having a small number of transmissions and a large amount of data in the data communication between the timing controller and the LED driver is a high-speed communication interface. The LED drive control data having a large number of transmissions and a small amount of data thereafter after performing the communication has an advantage of reducing power consumption by performing communication through a low speed communication interface.

Claims (17)

A control data generator for generating current control data for setting a current value to be applied to each of the plurality of LEDs and on / off timing control data for controlling on / off timing of each of the plurality of LEDs; A timing control unit including a first transmission module for outputting to an external circuit and a second transmission module for outputting the on / off timing control data to an external circuit; A first receiving module receiving the current control data, a second receiving module receiving the on / off timing control data, and a current for each of the plurality of LEDs according to the current control data and the on / off timing control data. LED driver with LED emission control unit for supply and on / off timing control Driving circuit for FSC liquid crystal display device comprising a The method according to claim 1, The plurality of LEDs include a red (R), green (G), blue (B) color LED driving circuit for the liquid crystal display device, characterized in that The method according to claim 1, The first transmission module is a drive circuit for an FSC liquid crystal display device, characterized in that the high speed data communication module The method according to claim 3, The high speed data communication module is a drive circuit for the FSC liquid crystal display, characterized in that for providing a data transmission clock of 250KHz The method according to claim 1, The second transmission module is a drive circuit for the FSC liquid crystal display device, characterized in that for providing a data transmission clock between 180 ~ 270Hz The method according to claim 1, Drive circuit for an FSC liquid crystal display device, characterized in that two data transmission lines are formed between the second transmission module and the second reception module. The method according to claim 1, The on / off timing control data is a drive circuit for an FSC liquid crystal display device, characterized in that the digital signal of the binary number Generating current control data for setting a current value to be applied to each of the plurality of LEDs from a timing controller and on / off timing control data for controlling on / off timing of each of the plurality of LEDs; Transmitting the current control data to the LED driver through a first communication interface at a first timing; Transmitting the on / off timing control data to the LED driver through a second communication interface at a second timing; Performing current supply and on / off timing control on each of the plurality of LEDs according to the current control data and on / off timing control data. Method of driving circuit for FSC liquid crystal display device comprising a The method of claim 8, Wherein the first timing is a timing preceding the second timing. The method of claim 8, The first communication interface is a driving method for a driving circuit for an FSC liquid crystal display device, characterized in that for operating in the I2C communication protocol Claim 11 was abandoned when the registration fee was paid. The method of claim 8, And the first communication interface is a high speed data communication interface. Claim 12 is abandoned in setting registration fee. 12. The method of claim 11, The high speed data communication interface is a drive method for a drive circuit for an FSC liquid crystal display, characterized in that data transmission is performed at a frequency of 250KHz. Claim 13 was abandoned upon payment of a registration fee. The method of claim 8, The second communication interface is a drive method for a drive circuit for an FSC liquid crystal display, characterized in that data transmission is performed at a frequency of 180 ~ 270Hz Claim 14 has been abandoned due to the setting registration fee. The method of claim 8, The on / off timing control data is transmitted via two data transmission lines. Claim 15 is abandoned in the setting registration fee payment. The method of claim 8, The on / off timing control data is a driving method for a driving circuit for an FSC liquid crystal display device, characterized in that the digital signal of the binary number. Claim 16 has been abandoned due to the setting registration fee. The method of claim 15, Wherein the digital signal is one of 00, 01, 10, and 11; Claim 17 has been abandoned due to the setting registration fee. The method according to claim 16, 00 corresponds to LED off, 01 corresponds to Red LED on, 10 corresponds to Green LED on, and 11 corresponds to Blue LED on. A method of driving a drive circuit for an FSC liquid crystal display

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