KR20030058732A - Circuit for driving a liquid crystal display device - Google Patents

Abstract

PURPOSE: A driving circuit for LCD is provided to remove a cause of the electromagnetic interference by preventing the output of a signal of a TTL level to the outside. CONSTITUTION: A driving circuit for LCD includes a scaler block(202), a source driving portion(204), and a gate driving portion(208). The scaler block is used for receiving an analog data signal, a synchronous signal, and a digital video input signal to control the resolution, generating a gate driving voltage and a gate control signal to drive gate lines, and outputting a data signal and a control signal to display images. The source driving portion receives the data signal and the control signal from the scaler block and provides the data signal and the control signal to a display panel. The gate driving portion receives the gate driving voltage and the gate control signal from the scaler block and drives gate lines of the display panel. The scaler block is formed with one IC.

Description

CIRCUIT FOR DRIVING A LIQUID CRYSTAL DISPLAY DEVICE}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more particularly, to a driving circuit of a liquid crystal display device capable of reducing electromagnetic interference (hereinafter referred to as "EMI").

Most electrical energy facilities produce some amount of electromagnetic noise, which is transmitted in the form of electromagnetic radiation through the air or conduction through conductors such as power lines. When other devices or systems are disturbed by the operation of the electromagnetic noise, this is called electromagnetic interference (hereinafter referred to as "EMI"). There are three factors in the electromagnetic interference phenomenon: noise sources that emit electromagnetic energy in the form of conduction or radiation, radio media that deliver electromagnetic energy, and damage devices that are disturbed by noise. If only one of these factors is excluded, electromagnetic interference (EMI) does not occur.

The liquid crystal display device includes a display panel made of liquid crystal and a driving circuit for driving the display panel. 1 is a block diagram of a driving circuit of a conventional liquid crystal display. As shown in FIG. 1, a conventional driving circuit 100 is mounted on three boards, an interface board 105, a source board 110, and a gate board 116. The analog / digital converter 101, the digital video input receiver 102, and the scaler 103 are mounted on the interface board 105, and the timing controller 107 and the source driver 109 are disposed on the source board 110. It is mounted. The gate driver 114 is mounted on the gate board 116. The scaler 103 on the interface board 105 and the timing controller 107 on the source board 110 are connected by a cable 106, and the source board 110 and the gate board 116 are connected by a cable 112. Connected by In Fig. 1, signal AA is an analog data signal, signal SS is a synchronization signal, and signal DD is a digital video input signal. Hereinafter, the signals AA, SS, and DD are collectively called an input signal. In addition, the arrows in FIG. 1 indicate the flow direction of the signal.

First, the scaler 103 in the interface board 105 adjusts the resolution so that an image optimized for the display panel is displayed. The analog / digital converter 101 converts an analog data signal into a digital signal and converts the signal into a signal level that the scaler 103 can process. The digital video input receiver 102 receives the digital video input signal from the outside and converts the digital video input signal into a signal level that can be processed by the scaler 103. In the source board 110, the timing controller 107 generates a data signal and a control signal for driving the display panel, provides the source signal to the source driver 109, and drives a gate driving voltage and a gate control signal to drive a gate line of the display panel. Is generated and provided to the gate driver 114. The source driver 109 receives the data signal and the control signal from the timing controller 107 and inputs them to the display panel so that an image is displayed on the display panel. In the gate board 116, the gate driver 114 receives the gate driving voltage and the gate control signal from the timing controller 107 and drives the gate line by turning on / off the gate line of the display panel.

As shown in FIG. 1, an interface cable 106 is required to input a signal finally generated by the interface board 105 to the timing controller 107 located on the source board 110. In addition, an interface cable 112 that serves as an interface between the source board 110 and the gate board 116 is required. In order to mount the interface cables 106 and 112 on the boards 105, 110 and 116, connectors are required, which are illustrated as being included in the interface cables 106 and 112 in FIG.

When the signals AA and SS are received by the analog / digital converter 101 or the signal DD is received by the digital video input receiver 102, the analog / digital converter 101 and the digital video input receiver 102 are used. ) Outputs the received signal to the scaler 103. The analog / digital converter 101 and the digital video input receiver 102 are not intended to simultaneously output to the scaler 103. The scaler 103 inspects an input signal and adjusts a signal for adjusting only one of the analog / digital converter 101 and the digital video input receiver 102 to be output. The analog / digital converter 101 and the digital video input receiver 102 Send to). At this time, the signal level output from the analog / digital converter 101 and the digital video input receiver 102 is generally a signal level of about 2.7V to 3.6V (hereinafter referred to as a "TTL level"). In this way, when a signal is input to the scaler 103, the scaler 103 adjusts the resolution so as to fit the display panel and outputs a TTL level signal to the timing controller 107. When the TTL level signal is input to the timing controller 107, the timing controller 107 outputs a TTL level signal for driving the source driver 109 and the gate driver 114.

When the image is displayed on the liquid crystal display using the conventional driving method as described above, a lot of electromagnetic interference occurs due to the use of signals of the TTL level, and in order to solve the electromagnetic interference problem, many circuits and mechanisms are used. Additional components, such as filter circuits, magnetic materials, shield chassis, etc. are required, and in the worst case, design changes are required, which is problematic in terms of time and cost. For reference, according to the company's experience, there are many problems with the electromagnetic wave in the conventional method, causing problems in terms of time and cost, and design change factors.

First of all, the most problematic part in terms of electromagnetic interference is the cable 106 part. Thus, in some cases, the portion 104 for reducing the signal level is added to the output portion of the scaler 103 and the portion 108 for amplifying the signal having the reduced level again in the timing controller 107, thereby improving the electromagnetic interference. There was a case. This solution has the disadvantage of increasing cost, and the higher the resolution, the more often it is applied and the greater the cost increase. Until now, the company developing the liquid crystal display developed only the source board 110 and the gate board 116, and the interface board 105 was developed by another company, so that the interface cable 106 had to exist.

Secondly, a part that causes many problems in terms of electromagnetic interference is between the timing controller 107 and the source driver 109. In order to solve the electromagnetic interference problem, the output of the timing controller 107 needs to be divided into two or four divisions, and a filter circuit must be additionally used to mechanically prevent radiation of electromagnetic waves. There are many cases where you need to use a shield chassis. The higher the resolution, the greater the cost.

Third, a portion that causes a lot of problems in terms of electromagnetic interference is a portion in which the analog video signal AA and the synchronization signal SS are input to the analog / digital converter 101. Although the input level of the data AA is lower than 1V or less, the synchronization signal SS is input together with a signal having a level of about 5V, which is a level higher than the TTL level. Since these two levels are mixed and input to the liquid crystal display, a separate electromagnetic interference filter circuit is added to the data input signal, or a magnetic material for preventing electromagnetic interference needs to be separately used for the input cable. Of these three reasons, the least impact on the electromagnetic interference, and the smallest increase in costs.

As a result, when the display device such as a monitor or a television is manufactured using a liquid crystal display device, the biggest cause of the electromagnetic interference is that the data signal transmitted for each block is at the level of the control signals. In order to solve this problem, a large amount of time and cost are added, and a display device using a liquid crystal display is being developed.

The present invention has been proposed to solve such a problem, and provides a driving circuit of a liquid crystal display device capable of greatly reducing the signal level in the aforementioned three parts and integrating overlapping parts to reduce the cause of electromagnetic interference. For the purpose of

1 is a block diagram of a driving circuit of a conventional liquid crystal display device.

2 is a block diagram of a driving circuit of a liquid crystal display according to an exemplary embodiment of the present invention.

3 is a block diagram of a driving circuit of a liquid crystal display according to another exemplary embodiment of the present invention.

4 is a block diagram of a driving circuit of a liquid crystal display according to another exemplary embodiment of the present invention.

In order to achieve the above object, the present invention provides a driving circuit for a liquid crystal display device having a display panel made of liquid crystal, which receives an analog data signal, a synchronization signal, and a digital video input, adjusts the resolution to fit the display panel, and A gate driving voltage and a gate control signal for driving a gate line of a display panel, a scaler block for generating and outputting a data signal and a control signal for displaying an image on the display panel, and the data signal and the control signal from the scaler block And a source driver configured to receive and provide the gate panel to the display panel, and a gate driver configured to receive the gate driving voltage and the gate control signal from the scaler block and to drive the gate line of the display panel. Implemented as an integrated circuit A is an aspect.

The scaler block includes an analog / digital converter for converting a signal level by receiving the analog data signal and the synchronization signal, a digital video input receiver for receiving a digital video input to convert a signal level, and the analog / digital conversion. Scaling means for receiving an output signal from the digital video input receiver and an output signal of the digital video input receiver, and receiving an output signal of the scaling means by receiving the output signal of the scaling means, and the data And a timing controller for generating a signal and the control signal, wherein the analog / digital converter and the digital video input receiver convert the received signal into a signal level that can be processed by the scaling means. The output signal of the scaler block has a signal level of 1/5 to 1/10 of the signal level of the transistor-transistor logic (TTL).

Preferably, the source driver and the scale block are mounted on one substrate. Preferably, the data signal and the control signal provided from the scaler block to the gate driver are patterned and transmitted through a panel. Preferably, the scaler block includes adjusting means for adjusting timing conditions.

In addition, the present invention provides a driving circuit for a liquid crystal display device having a display panel made of liquid crystal, the method comprising: receiving only a digital video input, adjusting a resolution to fit the display panel, and driving a gate line of the display panel; And a scale block for generating and outputting a gate control signal, a data signal for displaying an image on the display panel, and a control signal, and a source driver for receiving the data signal and the control signal from the scaler block and providing the data signal to the display panel. And a gate driver configured to receive the gate driving voltage and the gate control signal from the scaler block and drive the gate line of the display panel, wherein the scaler block is implemented as one integrated circuit.

According to the configuration of the present invention as described above, the primary cause of the electromagnetic interference is eliminated by preventing the TTL level signal from coming out. In addition, since the level of signals between the scaler and the source driver is reduced to about 1/5 to 1/10 of the TTL level, the secondary cause of the electromagnetic interference is eliminated. In addition, by configuring a digital dedicated scaler, the third cause of electromagnetic interference is eliminated. That is, according to the present invention, all major causes of electromagnetic interference are eliminated. It also reduces design time by half, dramatically improves image quality and reliability, and cuts costs by more than half.

Hereinafter, with reference to the accompanying drawings will be described an embodiment of the present invention; In the drawings, the same reference numerals are used to refer to the same or similar components and signals for the sake of consistency of description.

2 is a block diagram of a driving circuit of a liquid crystal display according to an exemplary embodiment of the present invention. As shown in FIG. 2, the driving circuit 200 includes a low level source board 201, a gate board 210, and an interface cable 206. The driving circuit 200 according to the present embodiment is a driving circuit (Fig. 1) in that the analog video signal AA, the synchronization signal SS and the digital video signal DD are directly input to the low level output scaler 202. 100). In addition, the low level output scaler 202 is distinguished in that it outputs a signal having a level of 1/5 to 1/10 times the previous TTL level to the low level source driver 204.

The low level output scaler 202 adjusts the resolution so as to receive an input signal and output an optimized resolution to the display panel. The level of the adjusted data signal and the control signal is 1 when compared with the TTL level. The output is at a level of about 5 to 1/10. That is, the low level output scaler 202 integrates the functions of the analog / digital converter 101, the digital video input receiver 102, the scaler 103, the timing controller 107, and the cable 106 in FIG. It is. This integration work is rather easy to be performed when designing the liquid crystal display. This is because a liquid crystal display device may have slightly different driving characteristics for each model or even for the same company. That is, the timing of the control signal output from the timing controller 107 and the output condition of data for optimizing the optical characteristics displayed on the liquid crystal display may vary for each liquid crystal display. Therefore, this integration work must be performed in the design of the liquid crystal display device so that the output can be adjusted to the optimal display condition. Therefore, the low level output scaler 202 preferably includes adjusting means for adjusting some timing conditions. In any case, according to the driving apparatus 200 according to the present embodiment, the interface cable (106 in FIG. 1), which has a greatest degree of electromagnetic interference in the past, enters the low level output scaler 202, thereby eliminating the greatest cause of electromagnetic interference. In addition, by reducing the output level of the low-level output scaler 202 by 1/5 to 1/10 times the conventional TTL level, the second cause of electromagnetic interference is eliminated. In other words, the two problems, which are the biggest causes of electromagnetic interference, are solved at once by the driving circuit 200 of the present embodiment.

The source driver 204 receives a low level data signal and a control signal output from the low level output scaler 202 and displays the image data on the display panel. The source driver 204 is mounted on the low level source board 201 together with the low level output scaler 202. The gate driver 208 drives the gate of the display panel as in the related art and is mounted on the gate board 210. Some of the signals output from the low level output scaler 202 are provided to the gate board 210 via the interface cable 206.

3 is a block diagram of a driving circuit of a liquid crystal display according to another exemplary embodiment of the present invention. As shown in FIG. 3, the drive circuit 300 according to the present embodiment is distinguished from the drive circuit (200 in FIG. 2) in that the low level output scaler 302 receives only a digital video input from the outside. The other parts are the same as in the case of the drive circuit (200 in FIG. 2).

As described above, the third cause of the electromagnetic interference is a portion where the analog video input signal and the synchronization signal are input together. Conventionally, the analog / digital converter (101 in FIG. 1) is not only a cause of electromagnetic interference, but also difficult to be technically configured, and has been an important cause of poor screen quality. In this embodiment, a digital dedicated low level output scaler 302 is constructed in which the function of the analog / digital converter (101 in FIG. 1) has been removed.

The difficulty of the firmware design technique encountered when configuring the analog / digital converter (101 in FIG. 1) is almost eliminated in this embodiment. Therefore, since the process that requires the most time when developing the display device using the liquid crystal display device is eliminated, the development period is drastically shortened. In addition, the analog / digital converter has been the biggest cause of poor image quality and reliability in a display device using a liquid crystal display device. The image quality and reliability of the displayed display device will be significantly improved.

4 is a block diagram of a driving circuit of a liquid crystal display according to another exemplary embodiment of the present invention. In FIG. 4, only one printed circuit board is used by removing the gate board. Incidentally, it is possible to remove the interface cable from the source board 401 to the existing gate board, and drive signals to the gate driver 404 are patterned through the panel.

The embodiments described herein are merely intended to enable those skilled in the art to easily understand and practice the present invention, and are not intended to limit the scope of the present invention. Therefore, those skilled in the art should note that various modifications or changes are possible within the scope of the present invention. The scope of the invention is defined in principle by the claims that follow.

According to the configuration of the present invention as described above, the primary cause of the electromagnetic interference is eliminated by preventing the TTL level signal from coming out. In addition, since the level of signals between the scaler and the source driver is reduced to about 1/5 to 1/10 of the TTL level, the secondary cause of the electromagnetic interference is eliminated. In addition, by configuring a digital dedicated scaler, the third cause of electromagnetic interference is eliminated. That is, according to the present invention, all major causes of electromagnetic interference are eliminated. It also reduces design time by half, dramatically improves image quality and reliability, and cuts costs by more than half.

Claims (8)

In a driving circuit of a liquid crystal display device having a display panel made of liquid crystal, Receives an analog data signal, a synchronization signal, and a digital video input, adjusts the resolution to fit the display panel, displays a gate driving voltage and a gate control signal for driving a gate line of the display panel, and displays an image on the display panel. A scaler block for generating and outputting a data signal and a control signal; A source driver configured to receive the data signal and the control signal from the scaler block and provide the data signal to the display panel; A gate driver configured to receive the gate driving voltage and the gate control signal from the scaler block and drive a gate line of the display panel Equipped, And the scaler block is implemented as a single integrated circuit. The method of claim 1, The scaler block An analog / digital converter for converting a signal level by receiving the analog data signal and the synchronization signal; A digital video input receiver for receiving the digital video input and converting a signal level; Scaling means for receiving an output signal of the analog / digital converter and the digital video input receiver, and adjusting the resolution to fit the display panel; A timing controller configured to receive an output signal of the scaling means and generate the gate driving voltage and the gate control signal, the data signal, and the control signal; Equipped, And the analog / digital converter and the digital video input receiver respectively convert the received signal into a signal level that can be processed by the scaling means. The method of claim 1, And the output signal of the scaler block has a signal level of 1/5 to 1/10 of the signal level of transistor-transistor logic (TTL). The method of claim 1, And the source driver and the scaler block are mounted on a single substrate. The method of claim 1, And the data signal and the control signal provided from the scaler block to the gate driver are patterned and transmitted through a panel. The method of claim 1, And said scaler block includes adjusting means for adjusting timing conditions. In a driving circuit of a liquid crystal display device having a display panel made of liquid crystal, It receives only a digital video input, adjusts the resolution so as to fit the display panel, and controls a gate driving voltage and a gate control signal for driving a gate line of the display panel, and a data signal and a control signal for displaying an image on the display panel. A scaler block to generate and output, A source driver configured to receive the data signal and the control signal from the scaler block and provide the data signal to the display panel; A gate driver configured to receive the gate driving voltage and the gate control signal from the scaler block and drive a gate line of the display panel Equipped, And the scaler block is implemented as a single integrated circuit. The method of claim 7, wherein The scaler block A digital video input receiver for receiving the digital video input and converting a signal level; Scaling means for receiving an output signal of the digital video input receiver and adjusting a resolution to fit the display panel; A timing controller configured to receive an output signal of the scaling means and generate the gate driving voltage and the gate control signal, the data signal, and the control signal; Equipped, And the digital video input receiver converts the received signal into a signal level that can be processed by the scaling means.