KR20210085983A - Emi reduction method and display device using the same - Google Patents

Abstract

The present invention relates to a method for reducing EMI and a display device using the same, which sense an electromagnetic field of an original signal applied to a signal transmission line using a first non-contact coupler, and supply an inverted signal of the original signal to a second non-contact coupler to inject the electromagnetic field of the inverted signal into the signal transmission line. The present invention can remove noise and reduce EMI without side effects by injecting a field of an inverted signal into a ground surface.

Description

EMI reduction method and display device using the same

The present invention relates to a level shifter for converting a voltage level of an input signal and a display device using the same.

Various flat panel display devices, such as a liquid crystal display device (LCD) and an electroluminescent display device, are on the market. The electroluminescent display is roughly classified into an inorganic light emitting display and an organic light emitting display according to the material of the light emitting layer. An active matrix type organic light emitting diode display includes an organic light emitting diode (hereinafter referred to as "OLED") that emits light by itself, and has a fast response speed and high luminous efficiency, luminance, and viewing angle. There are advantages.

Such a display device includes a display panel driving circuit for writing pixel data of an input image to pixels, a timing controller for controlling the display panel driving circuit, and the like. The display panel driving circuit includes a data driver supplying pixel data voltage to data lines, a gate driving circuit supplying a gate signal (or scan signal) to gate lines (or scan lines), and the like. The data driver may be implemented as a drive integrated circuit (IC).

Recently, regulation of EMI (Electro-Magnetic Interface) of home appliances and communication devices has been strengthened. In the case of display devices, various EMI reduction technologies are applied to meet EMI standards.

A plurality of signal transmission lines are connected to circuits of the display device. When a ripple is generated in a signal applied to these signal transmission lines or a voltage of the signal is inverted, a peak current is generated, and thus EMI may be generated.

In order to improve EMI, a ripple of the signal transmission path may be detected and an inverted amplified signal of the detected ripple may be applied to the signal transmission path. In this method, a separate feedback wire for ripple detection and a pin of the IC chip must be added.

EMI can be reduced by generating an anti-phase signal of an original signal applied to a signal transmission line and applying an anti-phase signal simultaneously with the original signal through a separate wire. In this method, timing matching is difficult according to a load difference between wires to which the original signal and the out-of-phase signal are applied, and may cause radiated emission in the low frequency band of the large screen model.

In the conventional EMI technology, it is difficult to reduce EMI caused by potential fluctuations occurring on the ground plane.

SUMMARY OF THE INVENTION The present invention aims to solve the above-mentioned needs and/or problems.

The problems of the present invention are not limited to the problems mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the following description.

The EMI reduction method of the present invention includes sensing an electromagnetic field of an original signal applied to a signal transmission line using a first non-contact coupler, generating an inverted signal of the original signal, and converting the inverted signal to a second non-contact coupler. and injecting the electromagnetic field of the inverted signal into the signal transmission line by supplying the inverted signal.

The display device of the present invention senses an electromagnetic field of an original signal applied to a signal transmission line using a first non-contact coupler to generate an inverted signal of the original signal, and supplies the inverted signal to a second non-contact coupler to provide the inverted signal a coupler driver injecting an electromagnetic field of the signal transmission line into the signal transmission line; and a printed circuit board on which an original signal generating unit generating the original signal and the coupler driving unit are mounted, and including a wiring through which the original signal is transmitted, a ground plane, the first non-contact coupler, and the second non-contact coupler. .

The signal transmission line includes the original signal generator, the wiring, and the ground plane.

The present invention provides a non-contact coupler for sensing an electromagnetic field on a signal transmission line on a PCB on which an IC chip on which at least one of a timing controller, a level shifter, a power supply, a non-signal generator, and a source drive IC is mounted, and a field of an inverted signal By disposing a contactless coupler injected into the transmission line, the field cancellation effect of the peak current of the original signal transmitted through the signal transmission line is reduced. Accordingly, the present invention generates an inverted signal of an original signal sensed on a signal transmission line and injects a field of the inverted signal into the signal transmission line to reduce a peak current, thereby eliminating noise and reducing EMI.

The present invention can remove noise and reduce EMI without side effects by injecting a field of an inverted signal into the ground plane.

Effects of the present invention are not limited to the effects mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art from the description of the claims.

1 to 4 are views showing a display device according to an embodiment of the present invention.
5 and 6 are waveform diagrams illustrating a method of driving pixels and touch sensors.
7 is a diagram schematically illustrating a shift register of a gate driver.
8 and 9 are diagrams illustrating a connection relationship between a display panel, a source PCB, a control board, and a main board.
10 is a diagram illustrating a transmission path of high voltage signals supplied to a display panel.
11 is a waveform diagram showing an EMI reduction method of the present invention.
12 is a view showing various embodiments of a coupler disposed close to a signal transmission line.
13 is a view showing various embodiments of an inversion signal generator.
14 is a view showing a field of an inverted signal injected into a signal transmission line.
15 is a view showing a field of an inverted signal injected into a ground surface of a PCB.
16 is a view showing an example of a coupler disposed around a screw for fixing the PCB.
17 is a diagram illustrating an example of a coupler disposed on an IC chip.
18 is a diagram illustrating an example of a coupler disposed on an inductor.
19 is a perspective view showing a first embodiment of a loop-type coupler having a two-layer structure.
20 is a cross-sectional view showing a cross-sectional structure of the loop-type coupler taken along the line “I-I'” in FIG. 19 .
21 is a perspective view showing a first embodiment of a loop-type coupler having a four-layer structure.
22 is a cross-sectional view showing a cross-sectional structure of the loop type coupler taken along the line “II-II'” in FIG. 21 .
23 is a block diagram showing a coupler driving unit according to an embodiment of the present invention.
24 is a diagram illustrating an example of a comparator.
25 is a waveform diagram illustrating an example in which an inverted signal is generated when the voltage of the sensed original signal is greater than or equal to a reference value.
26 to 29 are waveform diagrams showing the enable timing of the coupler driver.
30 is a waveform diagram showing a square wave signal used for simulation.
31 is a simulation result diagram showing an EMI attenuation effect according to whether or not an inverted signal is field injected.

Advantages and features of the present invention and methods of achieving them will become apparent with reference to the embodiments described below in detail in conjunction with the accompanying drawings. The present invention is not limited to the embodiments disclosed below, but will be implemented in various different forms, only the embodiments allow the disclosure of the present invention to be complete, and those of ordinary skill in the art to which the present invention pertains It is provided to fully understand the scope of the invention, and the present invention is only defined by the scope of the claims.

Since the shapes, sizes, proportions, angles, numbers, etc. disclosed in the drawings for explaining the embodiments of the present invention are exemplary, the present invention is not limited to the matters shown in the drawings. Like reference numerals refer to substantially like elements throughout. In addition, in describing the present invention, if it is determined that a detailed description of a related known technology may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

In the present invention, when "comprising", "including", "having", "consisting", etc. mentioned in the present invention are used, other parts may be added unless 'only' is used. When a component is expressed in the singular, it may be construed as the plural unless specifically stated otherwise.

In interpreting the components, it is interpreted as including an error range even if there is no separate explicit description.

In the case of a description of the positional relationship, for example, when the positional relationship between two components is described as 'on', 'on', 'on', 'beside', ' One or more other elements may be interposed between those elements in which 'directly' or 'directly' are not used.

1st, 2nd, etc. may be used to distinguish the components, but the functions or structures of these components are not limited to the ordinal number or component name attached to the front of the component. Since the claims are described based on essential elements, the ordinal numbers placed before the component names in the claims may not match the ordinal numbers placed before the component names of the embodiments.

The following embodiments can be partially or wholly combined or combined with each other, and technically various interlocking and driving are possible. Each of the embodiments may be implemented independently of each other or may be implemented together in a related relationship.

The display device of the present invention provides an electromagnetic field (hereinafter, referred to as an electromagnetic field) on a signal transmission line including an IC chip in which an original signal generator for generating an original signal is integrated, a wiring of a printed circuit board (PCB) on which the IC chip is mounted, and a ground surface, etc. Sensing the "field" (abbreviated as "field") detects the peak components (current, voltage) that cause EMI. In the display device of the present invention, the phase of the sensed peak component is inverted and the amplified field of the inverted signal is injected into the original signal or the ground plane (the power plane) that is the return path of the original signal. According to the present invention, noise reduction of an original signal and EMI of a display device can be minimized without side effects by using the field cancellation technology.

The present invention can be applied to any display device such as a liquid crystal display (LCD), an electroluminescent display, and the like.

Hereinafter, various embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 to 4 , a display device according to an embodiment of the present invention includes a display panel 100 and a display panel driving circuit.

The display panel 100 includes a pixel array AA that displays pixel data of an input image. Pixel data of the input image is displayed on the pixels of the pixel array AA. The pixel array AA includes a plurality of data lines DL, a plurality of gate lines GL crossing the data lines DL, and pixels arranged in a matrix form. In addition to the matrix form, the arrangement of pixels may be formed in various ways, such as a form in which pixels emitting the same color are shared, a stripe form, a diamond form, and the like.

When the resolution of the pixel array AA is n*m, the pixel array AA includes n pixel columns and m pixel lines intersecting the pixel columns. The pixel column includes pixels arranged along the y-axis direction. The pixel line includes pixels arranged along the x-axis direction. One horizontal period (1H) is the time divided by one frame period by the total number of pixel lines. During one horizontal period (1H), pixel data is simultaneously written to the pixels of one pixel line.

Each of the pixels may be divided into a red sub-pixel, a green sub-pixel, and a blue sub-pixel to implement color. Each of the pixels may further include a white sub-pixel. Each of the sub-pixels 101 includes a pixel circuit. The pixel circuit includes a pixel electrode, a plurality of thin film transistors (TFTs), and a capacitor. The pixel circuit is connected to the data line DL and the gate line GL.

Touch sensors are disposed on the screen of the display panel 100 to realize a touch screen. The touch input may be sensed using separate touch sensors or may be sensed through pixels. The touch sensors may be implemented as in-cell type touch sensors arranged on the screen of a display panel or embedded in a pixel array as an on-cell type or an add-on type. can

When in-cell touch sensors are disposed on the display panel 100 , the pixel array AA may further include sensor lines SL connected to the pixels. The in-cell type touch sensor SE may be implemented as a capacitive type touch sensor, for example, a mutual capacitance sensor or a self capacitance sensor. Self-capacitance is formed along a single-layer conductor line formed in one direction. Mutual capacitance is formed between two orthogonal conductor lines. 4 illustrates a self-capacitance type touch sensor, the touch sensors of the present invention are not limited thereto. The touch sensors SE are connected to the source driver 110 through sensor lines SL.

The electrode patterns of each of the in-cell type touch sensors SE may be formed in a pattern obtained by dividing the common electrode of the pixels into predetermined sizes. The common electrode is an electrode connected to a plurality of pixels to apply a common voltage Vcom to the pixels. One touch sensor SE is connected to the plurality of sub-pixels to supply a common voltage Vcom to the plurality of pixels during the display period, and is driven by the touch sensor driver RIC during the touch sensing period to receive a touch input. sense Accordingly, the touch sensor SE is a common electrode that supplies a common voltage Vcom to pixels during the display period, and is a sensor electrode that senses a touch input during the touch sensing period. In FIG. 4, “PE” denotes a pixel electrode formed in each of the sub-pixels.

The display panel driving circuit includes a source driver 110 , a gate driver 120 , and a timing controller 130 for controlling operation timings of the driving circuits 110 and 120 . The display panel driving circuit writes input image data to pixels of the display panel 100 under the control of the timing controller 130 .

The source driver 110 includes a data driver SIC that supplies the data voltage of the input image to the data lines DL during the display period. The source driver 110 may further include a touch sensor driver RIC connected to the touch sensors SE through the sensor lines SL to drive the touch sensors during the touch sensing period.

The data driver SIC converts pixel data DATA of an input image received as a digital signal from the timing controller 130 into an analog gamma compensation voltage for every frame, and outputs a data signal. The data driver SIC may generate a data signal using a digital-to-analog converter (hereinafter referred to as a “DAC”) that converts a digital signal into an analog gamma compensation voltage. The data signal is supplied to the data lines DL.

The touch sensor driver RIC includes a multiplexer 231 and a sensing circuit 232 as shown in FIG. 6 . The multiplexer 231 selects the sensor lines SL connected to the sensing circuit 232 under the control of the touch sensor controller 320 . The multiplexer 231 may supply the common voltage Vcom during the display period under the control of the touch sensor controller 320 . Each of the multiplexers 231 may reduce the number of channels of the sensing circuit 232 by sequentially connecting the sensor lines SL to the channels of the sensing circuit 232 during the touch sensing period.

The display panel driving circuit may further include a demultiplexer array 112 disposed between the source driver 110 and the data lines DL.

The demultiplexer array 112 sequentially connects one channel of the source driver 110 to a plurality of data lines DL to time-divide a data voltage output from one channel of the source driver 110 to the data lines DL. The distribution may reduce the number of channels of the source driver 110 .

The source driver 110 may be integrated in each of the source drive ICs DIC shown in FIGS. 8 and 9 . The source drive IC (DIC) may be mounted on a chip on film (COF) and connected between the source PCB 152 and the display panel 100 .

The gate driver 120 may be disposed in a bezel area in which an image is not displayed on the display panel 100 .

The gate driver 120 receives a gate timing control signal received from a level shifter 140 , generates a gate signal (or a scan signal), and supplies it to the gate lines GL. The gate driver 120 may shift the gate signal using a shift register. The gate signal applied to the gate lines GL turns on the switch element of the sub-pixels to sequentially select the pixels to which the voltage of the data signal is charged one pixel line by one. The gate signal may be generated as a pulse signal swinging between the gate high voltage VGH and the gate low voltage VGL.

The level shifter 140 converts the voltage of the control signal received from the timing controller 130 . For example, the level shifter 140 converts a high logic voltage (or high potential input voltage) of an input signal received as a digital signal voltage level into a gate high voltage (VGH), and a low logic voltage (or low voltage) of the input signal. potential input voltage) into a gate low voltage (VGL). The output signal of the level shifter 140 may be transmitted to at least one of the demultiplexer array 112 and the gate driver 120 .

The timing controller 130 multiplies the input frame frequency by i to control the operation timings of the display panel drivers 110 and 120 with a frame frequency of the input frame frequency Хi (i is a positive integer greater than 0) Hz. The input frame frequency is 60 Hz in the NTSC (National Television Standards Committee) scheme and 50 Hz in the PAL (Phase-Alternating Line) scheme.

The timing controller 130 receives pixel data of an input image and a timing signal synchronized therewith from the host system 200 . The timing controller 130 transmits the pixel data of the input image to the source driver 110 . The timing signal includes a vertical synchronization signal Vsync, a horizontal synchronization signal Hsync, a clock signal DCLK, and a data enable signal DE. Since the vertical period and the horizontal period can be known by counting the data enable signal DE, the vertical synchronization signal Vsync and the horizontal synchronization signal Hsync may be omitted. The data enable signal DE has a period of one horizontal period (1H).

The timing controller 130 includes a data timing control signal for controlling the source driver 110 , a gate timing control signal for controlling the gate driver 120 , and a demultiplexer array based on the timing signal received from the host system 200 . A MUX control signal for controlling the switch elements of 112 may be generated. The gate timing control signal may include a gate start pulse (GST), a shift clock (GCLK), and the like. The start pulse GST defines a start timing of the gate driver 120 in every frame period. The shift clock GCLK defines a shift timing of the gate signal output from the gate driver 120 . The timing controller 130 may generate a control signal for controlling the level shifter 140 .

The host system 200 may be any one of a television (Television), a set-top box, a navigation system, a personal computer (PC), a home theater, a vehicle display, a mobile system, and a wearable system. In the mobile device and the wearable device, the source driver 110 , the timing controller 130 , the level shifter 140 , and the like may be integrated into one drive IC (not shown).

In the mobile system, the host system 200 may be implemented as an application processor (AP). The host system 200 may transmit pixel data of an input image to the drive IC through a Mobile Industry Processor Interface (MIPI). The host system 200 may be connected to the drive IC through a flexible printed circuit, for example, a flexible printed circuit (FPC).

The display device of the present invention further includes a power supply unit 400 .

The power supply unit 400 generates a DC voltage required for driving the pixel array of the display panel 100 and the display panel driving circuit using a DC-DC converter. The DC-DC converter may include a charge pump, a regulator, a buck converter, a boost converter, a buck-boost converter, and the like. The power supply unit 400 adjusts the DC input voltage from the host system 200 to obtain a gamma reference voltage (VGMA) and a gate high voltage (VGH). A DC voltage such as a gate low voltage VGL, half VDD (HVDD), and a common voltage of pixels may be generated. The gamma reference voltage VGMA is supplied to the source driver 110 . The half VDD voltage is half voltage compared to VDD and may be used as an output buffer driving voltage of the source drive IC (DIC). The gamma reference voltage VGMA is divided for each gray level through a voltage dividing circuit and supplied to the DAC of the source driver 110 .

The display device of the present invention further includes a no-load signal generator 401 . The no-load signal generator 401 generates the no-load signal LFD as shown in FIGS. 5 and 6 by switching the common voltage Vcom and the gate low voltage VGL input from the power source 400 . The no-load signal LFD may be generated as an AC signal swinging between the common voltage Vcom and the gate low voltage VGL. The no-load signal generator 401 generates a no-load signal LFD in response to the touch enable signal Tsync and supplies it to the touch sensor driver RIC of the source driver 110 . The no-load signal LFD is applied to the data line DL, the gate line GL, and the sensor lines SL for each touch sensing period. During the touch sensing period, the no-load signal LFD applied to the sensor lines SL supplies electric charges to the touch sensors SE, and a touch sensor driving signal that minimizes parasitic capacitance between the adjacent sensor lines SL. to be.

One frame period of the display device including the in-cell touch sensor may be time-divided into one or more display periods and one or more touch sensing periods. As shown in FIG. 3 , the pixel array AA of the display panel 100 is divided into two or more blocks B1 to BM and is time-division driven in block units. Pixels belonging to one block may be driven for each display period. The blocks B1 to BM do not need to be physically divided on the display panel 100 and are divided driving regions in which driving timings are separated according to the control of the timing controller 130 . Since the pixel array AA is driven in display sections, it is dividedly driven with a touch sensing section therebetween. The pixels of the pixel array AA are not driven during the touch sensing period and maintain their previous state.

Pixels of the blocks B1 to BM are time-division driven with a touch sensing section interposed therebetween. For example, as shown in FIG. 5 , after the pixels of the first block B1 are driven during the first display period D1 and the current frame data is written to the pixels, the first touch sensing period T1 . Touch input is sensed over the entire screen while it is running. Following the first touch sensing period T1 , the pixels of the second block B2 are driven during the second display period D2 to write the current frame data to the pixels. Subsequently, a touch input is sensed over the entire screen during the second touch sensing period T2. Here, the touch input includes a direct touch input of a finger or a stylus pen, a proximity touch input, a fingerprint touch input, and the like.

Referring to FIG. 4 , the sensing circuit 232 supplies the no-load signal LFD to the touch sensors SE through the multiplexer 231 and the sensor lines SL during the touch sensing period to the touch sensors SE. charge a charge in The sensing circuit 232 amplifies and integrates the amount of charges of the touch sensors SE received from the sensor line SL connected through the multiplexer 231 , and then converts it into digital data to sense a change in capacitance before and after a touch input. To this end, the sensing circuit 232 includes an amplifier for amplifying the touch sensor signal received from the touch sensor SE, an integrator for accumulating the output voltage of the amplifier, and an analog-to-digital converter for converting the voltage of the integrator into digital data. -Digital Converter, hereinafter referred to as "ADC") and the like. The digital data output from the ADC is transmitted to the touch sensor controller 320 as touch data indicating a change in capacitance of the touch sensor SE before and after a touch input. The sensing circuit 232 may sequentially drive the touch sensors SE in units of a touch sensor group having a predetermined size under the control of the touch sensor controller 320 . The touch sensor group includes a plurality of touch sensors SE.

The touch sensor controller 320 compares the touch data received from the touch sensor driver RIC with a preset threshold, detects touch data higher than the threshold, and generates coordinates XY of each touch input. The touch sensor controller 320 transmits the coordinates XY of each touch input to the host system 200 . The touch sensor controller 320 outputs a touch enable signal defining a touch sensor driving timing, an ADC clock, and the like, and supplies it to the touch sensor driver RIC. The touch sensor controller 320 may be implemented as a micro control unit (MCU), but is not limited thereto.

The no-load signal LFD minimizes the parasitic capacitance between the touch sensors SE and the pixels during the touch sensing periods T1 and T2, so that the signal to noise ratio of the touch sensor signal (Signal to Noise Ratio, hereinafter " SNR") can be improved.

The display device of the present invention further includes a coupler driving unit 500 . The coupler driver 500 senses a field on the signal transmission line, converts it into a voltage, and detects a peak component of an original signal transmitted through the signal transmission line. Since the original signal causing EMI is a square wave signal, a peak current may be generated on the signal transmission line when the potential is reversed. The coupler driving unit 500 generates an inverted signal of the peak component of the original signal, and injects the field of the inverted signal into the IC chip existing on the signal transmission line, the wiring of the signal transmission line, or the ground plane of the original signal. offset

7 is a diagram schematically illustrating a shift register of the gate driver 120 . The shift register of the gate driver 120 includes dependently connected stages SR(n-1) to (n+2). The shift register receives the start pulse GST or the carry signal CAR and generates output signals [OUT(n-1)) to (n+2)] according to the timing of the clock CLK. The carry signal CAR may be output from a previous stage.

Each of the stages [SR(n-1) to (n+2)] includes a control unit 60 for charging and discharging the Q node and the QB node, and charging the gate line according to the Q node voltage to increase the waveform of the gate signal ( rising) and includes a buffer that discharges the gate line according to the QB node voltage. The buffer includes a pull-up transistor Tu and a pull-down transistor Td. The output signals OUT(n-1) to (n+2) of the stages SR(n-1) to (n+2) are gate signals sequentially applied to the gate lines.

In the case of a large-screen display device, the source PCBs 152 may be divided into a plurality as shown in FIGS. 8 and 9 .

8 and 9 , the control board CPCB includes first and second source PCBs 152 and 153 through a flexible circuit board, for example, a flexible flat cable (FFC) 151 and a connector 151a. ) can be connected to The control board CPCB may be connected to the main board 201 of the host system 200 through the flexible circuit board 150 and the connector 152b.

The source drive ICs DIC are connected between the source PCBs 152 and 153 and the display panel 100 .

The timing controller 130 and the level shifter 140 may be mounted on the control board CPCB as shown in FIG. 8 or on each of the source PCBs 152 and 153 as shown in FIG. 9 .

The coupler driver 500 may be mounted on a PCB of a source PCB (SPCB) or a control board (CPCB).

10 is a diagram illustrating a transmission path of high voltage signals supplied to a display panel. The voltages output from the level shifter 140 are relatively high voltages, for example, a gate high voltage VGH and a gate low voltage VGL. The output voltage of the level shifter 140 may be supplied to the gate driver 120 and the demultiplexer array 112 of the display panel 100 via a long transmission line. The no-load signal output from the no-load signal generator 401 may be supplied to the source drive ICs DIC via a long transmission line. These voltages are generated as relatively high alternating current signals. The signal transmission line to which this voltage is applied is generated as a relatively high AC signal and passes through a long transmission line such as an IC chip, a control board PCB, a connector, a flexible circuit board (FFC), and a source PCB. A peak current appears along the signal transmission line, and EMI is generated due to the peak current.

A peak current (b) may be generated in the original signal (a) transmitted through the signal transmission line of FIG. 11 . In the EMI reduction method of the present invention, the field of the original signal (a) is sensed by a coupler on a signal transmission line and converted into a voltage (c). The EMI reduction method can generate an inverted signal of the sensed original signal as shown in (d) of FIG. 11 (d) and appropriately amplify the voltage of the inverted signal (e).

In the EMI reduction method, the field of the original signal is offset by injecting the field of the inverted signal onto the signal transmission line through a coupler (f and g). As a result, as shown in (d) of FIG. 11, the peak current flowing through the signal transmission line is reduced due to the field cancellation effect. When the peak current on the signal transmission line is reduced, noise can be removed and EMI can be minimized. The field of the original signal is sensed by at least one circuit component of an IC chip, a PCB, a connector, a flexible circuit board, and a ground plane existing on the signal transmission line, and the field of the inverted signal can be injected into these circuit components. .

The coupler driver 500 includes a first coupler for sensing the field of the original signal on the signal transmission line, and a second coupler for injecting the field of the inverted signal into the signal transmission line. The first coupler and the second coupler include a metal structure that does not directly contact a pin of an IC chip present on a signal transmission line, a PCB wiring, and a ground plane. Each of the first coupler and the second coupler may be implemented as a non-contact coupler of various types, such as a loop type, a horizontal type, and a vertical type, as shown in FIG. 12 .

The loop-type coupler 12 wraps the upper and lower sides and left and right sides of the signal transmission line 14 as shown in (a) of FIG. 12 in a closed loop form. The horizontal type coupler 12 is parallel to the signal transmission line 14 as shown in FIG. 12B. The vertical type coupler 12 crosses the signal transmission line 14 as shown in FIG. 12(c).

The coupler driving unit 500 generates an inverted signal of the original signal detected through the first coupler. The inverting signal generator may include at least one of an inverter, a NOR circuit XNOR, a non-inverting amplifier, and an inverting amplifier. The inverter is connected to one first coupler as shown in (a) of FIG. 13 and outputs an inverted signal (Y) of the input signal (A). The exclusive NOR circuit XNOR is connected to the two first couplers as shown in FIG. 13B to output the XNOR operation result Y of the two input signals A and B. The non-inverting amplifier and the inverting amplifier include an operational amplifier and resistors R1 and Rf connected between an inverting input terminal and an output terminal of the operational amplifier. The non-inverting amplifier amplifies the signal Vi of the first coupler input to the non-inverting input terminal (+) as shown in FIG. 13C . The inverting amplifier amplifies the signal Vi of the first coupler input to the inverting input terminal as shown in (d) of FIG. 13 .

14 is a view showing a field of an inverted signal injected into a signal transmission line. The second coupler may be disposed adjacent to the signal transmission line in various structures as shown in FIG. 12 . The second coupler receives the inverted signal of the original signal and injects the field F of the inverted signal into the signal transmission line 14 .

15 is a view showing a field of an inverted signal injected into a ground surface of a PCB.

Referring to FIG. 15 , the source PCB (SPCB), the control board (CPCB), the main board 201, and the like include the PCB. Such a PCB has a wide ground plane MGND.

In the example of FIG. 15 , a PEM Nut and a screw 202 fix the PCB of the main board 201 on a metal chassis 203 . The second coupler injects the field of the inverted signal to the ground plane of the PCB. The field of the inverted signal injected into the ground plane is transmitted to the metal chassis 203 to reduce the EMI field radiated through the metal chassis 203 .

The second coupler may be disposed on one ground surface of the PCB or the first coupler may be disposed on the other ground surface of the PCB. The first coupler and the second coupler may be disposed around the screw 202 for fixing the PCB as in the example of FIG. 16 .

16 is a view showing an example of a coupler disposed around a screw for fixing the PCB.

Referring to FIG. 16 , the PCB may be implemented as a multilayer PCB. A ground metal pattern may be formed between the top surface 21 and the bottom surface 26 of the PCB around the screw 202 . The metal pattern of the upper surface 21 and the lower surface 26 of the PCB may be connected through a via hole 24 .

The first coupler 22 and the second coupler 23 may be disposed around the screw 202 . The first coupler 22 and the second coupler 23 may be formed in an intermediate layer between the top and bottom surfaces of the PCB. The first coupler 22 and the second coupler 23 may be patterned to surround the via hole 24 .

17 is a diagram illustrating an example of a coupler disposed on an IC chip.

Referring to FIG. 17 , the coupler 30 may be disposed on a circuit board of an IC chip. For example, the coupler 30 may be disposed around a pin connected to the signal transmission line 32 on a circuit board of an IC chip on which the timing controller 130 is integrated. The coupler 30 may be implemented as a loop-type coupler formed in an intermediate layer between the top and bottom surfaces of the circuit board of the IC chip. The loop of the loop type coupler may be formed in a structure surrounding the via hole without contacting the via hole connecting the metal pattern of the upper surface 33 and the lower surface 34 of the circuit board. The coupler 30 may be a first coupler for sensing an original signal or a second coupler for injecting an inverted signal.

A buck converter, a boost converter, and a buck-boost converter of the power supply unit 400 include a transistor for switching a current flowing through an inductor. A lot of peak current flows in the inductor. 18 is a diagram illustrating an example of a coupler disposed on an inductor.

Referring to FIG. 18 , the inductor 42 is mounted on the substrate of the PCB 40 . The PCB 40 includes an input pad 41 connected to an input terminal of the inductor 42 and an output pad 43 connected to an output terminal of the inductor. The coupler 44 may be formed in a loop shape surrounding the input pad and the output pad of the inductor 42 on the PCB. The coupler 44 disposed adjacent to the inductor 42 may include one or more of a first coupler and a second coupler.

The first and second couplers may be disposed adjacent to the signal transmission line by being spaced apart by a predetermined distance on the signal transmission line. In the loop type coupler structure, the wiring of the signal transmission path may be inserted into each loop of the first and second couplers in a non-contact state.

The loop type coupler may be implemented using a multilayer PCB as shown in FIGS. 19 to 22 .

19 is a perspective view showing a first embodiment of a loop-type coupler having a two-layer structure. 20 is a cross-sectional view showing a cross-sectional structure of the loop type coupler taken along the line “I-I'” in FIG. 19 .

19 and 20 , the loop type coupler 282 includes metal patterns disposed on two layers L1 and L2 of the PCB and connected in a loop shape through a via hole. The wiring of the signal transmission line 281 may cross the loop of the loop type coupler 282 with the insulating layer of the PCB interposed therebetween. Metal patterns of the signal transmission line 281 formed on the two layers L1 and L2 of the PCB at a portion crossing the loop of the loop-type coupler 282 may be connected through via holes.

21 is a perspective view showing a first embodiment of a loop-type coupler having a four-layer structure. 22 is a cross-sectional view showing a cross-sectional structure of the loop type coupler taken along the line “II-II'” in FIG. 21 .

21 and 22 , the loop-type coupler 302 includes metal patterns disposed on the first layer L01 and the fourth layer L04 of the PCB and connected in a loop through a via hole. The signal transmission line 302 crosses the loop of the loop type coupler 302 at the layers LO2 and LO3 between the first layer L01 and the fourth layer L04 at the intersection with the loop type coupler 302. It may include a metal pattern.

23 is a block diagram showing a coupler driving unit 500 according to an embodiment of the present invention.

The coupler driving unit 500 may include a sensing unit 251 , an inverted signal generator 252 , and an inverted signal output unit 253 as shown in FIG. 23A . The sensing unit 251 senses the field of the original signal on the signal transmission line using the first coupler and converts it into a voltage. The sensing unit 251 detects a peak component of the original signal on the signal transmission line. The inverted signal generating unit 251 generates an inverted signal of the original signal input from the sensing unit 21 . The inverted signal may be amplified. The inverted signal output unit 253 supplies an inverted signal to the second coupler. The second coupler injects the field of the inverted signal into the signal transmission line to cancel the field of the original signal.

The coupler driving unit 500 includes a comparator 254 connected between the sensing unit 251 and the inversion signal generating unit 252 as shown in FIG. 23B . The comparator 254 compares the original signal input from the sensing unit 251 with a predetermined reference value, and outputs an output signal of an activation level when the magnitude of the peak component of the sensed original signal is greater than the reference value. The inverted signal generator 252 may generate the inverted signal only when the original signal is greater than the reference value under the control of the comparator 254 .

The comparator 254 includes an operational amplifier that compares the reference voltage Vref set to a predetermined reference value and the sensing voltage Vsen of the original signal as shown in FIG. 24 . The sensing voltage Vsen is input to the non-inverting input terminal (+) of the operational amplifier, and the reference voltage Vref is input to the inverting input terminal (-) of the operational amplifier. The voltage dividing circuits R1 and R2 divide the voltage Vin to set the voltage level of the reference voltage Vref. The comparator 254 outputs an output signal Vcomp of a high level when the peak voltage of the original signal and the sensing voltage Vin are greater than the reference voltage Vref.

The coupler driver 500 may further include a switch element connected between the comparator 254 and the inversion signal generator 252 to switch the sensing voltage Vsen. This switch element is turned on/off according to the voltage level of the output signal Vcomp of the comparator 254 . The switch element is turned on when the output signal Vcomp of the comparator 254 is at a high level and supplies the sensed original signal voltage Vsen to the inverted signal generator 253 . Accordingly, the inversion signal generator 253 may generate the inversion signal only when the sensed original signal is greater than the reference value.

25 is a waveform diagram illustrating an example in which an inverted signal is generated when the voltage of the sensed original signal is greater than or equal to a reference value.

Referring to FIG. 25 , it is assumed that the peak voltage Va of the original signal Vi sensed through the first coupler is equal to (a). The peak voltage Va of the original signal Vi is compared with the reference voltage Vref as shown in (b). As shown in (c), the inverted amplified signal Vo may be generated only when the voltage a of the sensed original signal Vi is greater than the reference voltage Vref. When the peak voltage Va of the sensed original signal Vi is less than the reference voltage Vref, the EMI is smaller than the allowable range and can be ignored.

26 to 29 are waveform diagrams showing the enable timing of the coupler driver.

Referring to FIG. 26 , the vertical synchronization signal Vsync defines one frame period. One frame period includes a vertical blank period in which there is no pixel data and an active period in which pixel data is written into pixels of the screen. During the active period, a data signal is output from the data driver 110 and a gate signal is output from the gate driver 120 .

The timing controller 130 resets the first and second enable signals ENS and ENI in synchronization with the start pulse GST for controlling the gate driver 120 , and then sets an activation level, for example, a high level. can occur with The first enable signal ENS controls the enable timing of the sensing unit 251 . The sensing unit 251 is driven in response to an activation level of the first enable signal ENS. The second enable signal ENS controls the enable timing of the inverted signal generator 252 . The inversion signal generator 252 is driven in response to the activation level of the second enable signal ENI. Accordingly, the coupler driver 500 senses the original signal on the signal transmission line during the active period in every frame period and injects the inverted signal into the signal transmission line.

The sensing unit 251 senses the field of the original signal on the signal transmission line through the first coupler in response to the activation level of the first enable signal ENS. The inverted signal generator 252 generates an inverted signal in synchronization with the activation level of the second enable signal ENI. Accordingly, in the example of FIG. 26 , the coupler driver 500 is reset in synchronization with the start pulse GST, and then senses the original signal on the signal transmission line during the active period in which the output signal of the gate driver 120 is generated, and performs an inversion signal. field is injected into the signal transmission line. When the sensing unit 251 and the inverted signal output unit 253 are enabled, noise is removed from the signal transmission line and EMI is reduced. Also, noise and EMI in the ground plane can be reduced.

Referring to FIG. 27 , the timing controller 130 resets the first and second enable signals ENS and ENI in the vertical blank period every frame period in synchronization with the pulse of the vertical synchronization signal Vsync, and then the active period During this time, the enable signals ENS and ENI may be generated at an activation level. The active period may be divided into display periods D1 , D2 ... D16 in which pixel data is written into pixels and touch sensing periods T1 , T2 , ... T16 in which touch sensors are driven.

The sensing unit 251 senses the field of the original signal on the signal transmission line through the first coupler during the active period in response to the activation level of the first enable signal ENS. The inverted signal output unit 253 outputs an inverted signal through the second coupler in response to the activation level of the second enable signal ENI.

28 and 29 , the timing controller 130 may switch the second enable signal ENI in response to the output signal Vcomp of the comparator 254 .

The timing controller 130 outputs the second enable signal ENI to the activation level when the output signal Vcomp of the comparator 254 is at an activation level, for example, a high level, and outputs the inverted signal generator ( 252) can be enabled. On the other hand, when the output signal Vcomp of the comparator 254 is at the deactivation level, the timing controller 130 outputs the second enable signal ENI to the deactivation level or to the output terminal of the second enable signal EMI. By floating, the inverted signal generator 252 may be disabled.

Accordingly, when the peak value of the original signal sensed on the signal transmission line is greater than the reference value, the field of the inverted signal is injected into the signal transmission line. On the other hand, when the peak value of the sensed original signal is smaller than the reference value, the inverted signal is not generated because the output Vcomp of the comparator 254 is maintained at the inactive level as shown in FIGS. 28 and 29 .

30 is a waveform diagram showing a square wave signal used for simulation. 31 is a simulation result diagram showing an EMI attenuation effect according to whether an inverted signal is field injected. In this simulation, a square wave signal as shown in FIG. 30 was applied to the wiring 233 of the PCB passing through the loop type couplers 231 and 232 as shown in FIG. 19 . The simulation program was run on Ansys Electronics Desktop. In the simulation result waveform, the x-axis is the frequency band (GHz), and the y-axis is the EMI intensity (dB). The dotted line in FIG. 31 is the EMI measured when the original signal is applied to the signal transmission preference, that is, the wiring 233 of the PCB. The solid line generates an inverted signal of the original signal, and shows a result of reducing EMI when a field of the inverted signal is injected into the wiring 233 through the second coupler 232 . As a result of injecting the field of the inverted signal into the wiring 233, it was confirmed that the EMI was significantly reduced to 5 [dB] or less.

Those skilled in the art from the above description will be able to see that various changes and modifications can be made without departing from the technical spirit of the present invention. Accordingly, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification, but should be defined by the claims.

12, 22, 23, 30, 231, 232, 282, 302: coupler
14, 32, 233, 281, 301: signal transmission line
21, 22: multiplexer 80: control unit of the level shifter
82, 84: driving unit of the level shifter 100: display panel
110: data driver 112: demultiplexer array
120: gate driver 130: timing controller
140, 141, 142: level shifter 150: control board
150, 151: flexible circuit board (FFC) 152, 153: source PCB
251: sensing unit 252: inverted signal generating unit
253: inverted signal output unit 400: power unit
401: no-load signal generating unit 500: coupler driving unit

Claims (18)

The electromagnetic field of the original signal applied to the signal transmission line is sensed using the first non-contact coupler to generate an inverted signal of the original signal, and the inverted signal is supplied to the second non-contact coupler to transmit the electromagnetic field of the inverted signal to the signal transmission Coupler driving unit injected into the line; and
A printed circuit board on which the original signal generating unit generating the original signal and the coupler driving unit are mounted, and including a wiring through which the original signal is transmitted, a ground plane, the first non-contact coupler, and the second non-contact coupler,
The signal transmission line includes the original signal generator, the wiring, and the ground surface. The method of claim 1,
a display panel on which a plurality of data lines, a plurality of gate lines, and pixels are disposed;
a data driver receiving pixel data of an input image, converting it into a data signal, and supplying it to the data lines;
a gate driver supplying a gate signal to the gate lines; and
a timing controller that transmits the pixel data of the input image to the data driver and controls the data driver and the gate driver;
a level shifter for shifting a voltage of a signal output from the timing controller; and
Further comprising a power supply for generating voltages of the data signal and the gate signal,
The timing controller is a display device for generating the original signal. 3. The method of claim 2,
The display panel further includes touch sensors and sensor lines connected to the touch sensors. 4. The method of claim 3,
a touch sensor driving unit connected to the sensor lines to supply a touch sensor driving signal to the touch sensors; and
Further comprising a no-load signal generator for generating the touch sensor driving signal by using the voltage input from the power supply,
The no-load signal generator generates the original signal. The method of claim 1,
Each of the first and second non-contact couplers,
One of a horizontal type coupler having a horizontal pattern disposed adjacent to the wiring in parallel with the wiring, a vertical type coupler having a vertical pattern crossing the wiring, and a loop type coupler having a loop pattern surrounding upper and lower sides and left and right sides of the wiring phosphorus display. The method of claim 1,
The first non-contact coupler,
Sensing the electromagnetic field of the original signal on the wire,
The second non-contact coupler,
A display device for injecting the electromagnetic field of the inverted signal into the wiring. The method of claim 1,
The first non-contact coupler,
Sensing the electromagnetic field of the original signal on the ground plane,
The second non-contact coupler,
A display device for injecting the electromagnetic field of the inversion signal into the ground plane. The method of claim 1,
The first non-contact coupler,
Sensing the electromagnetic field of the original signal from the pin of the IC chip integrated with the original signal generator,
The second non-contact coupler,
A display device for injecting an electric field of the inverted signal into a pin of an IC chip integrated with the original signal generator. The method of claim 1,
The first non-contact coupler,
Sensing the electromagnetic field of the original signal from the via hole of the printed circuit board,
The second non-contact coupler,
A display device for injecting an electric field of the inversion signal into a via hole of the printed circuit board. The method of claim 1,
a power supply including at least one of a Buck converter, a Boost converter, and a Buck-Boost converter;
The power unit includes an inductor mounted on the printed circuit board,
wherein the printed circuit board includes an input pad connected to an input terminal of the inductor and an output pad connected to an output terminal of the inductor;
and at least one of the first and second non-contact couplers includes a loop surrounding the input pad and the output pad. 5. The method of claim 4,
The coupler driving unit,
a sensing unit that senses the field of the original signal through the first non-contact coupler and converts it into a voltage;
an inverted signal generating unit for generating an inverted signal of the original signal input from the sensing unit;
and an inverted signal output unit for outputting an inverted signal of the original signal to the second non-contact coupler. 12. The method of claim 11,
and a comparator for comparing a peak component of the original signal input from the sensing unit with a predetermined reference value. 13. The method of claim 12,
The inversion signal generating unit,
and a comparator configured to generate the inverted signal when a peak component of the original signal is greater than the reference value. 12. The method of claim 11,
The timing controller is
generating a start signal and a clock signal for driving the shift register of the gate driver;
supplying a first enable signal to the sensing unit to drive the sensing unit;
A display device for driving the inverted signal output unit by supplying a second enable signal to the inverted signal output unit. 15. The method of claim 14,
The timing controller is
The first and second enable signals are reset in synchronization with the start signal, and during an active period when an output is generated from the shift register of the gate driver, the enable signals are generated at an activation level to generate the sensing unit and the inverted signal driving wealth,
A display device for driving the inverted signal output unit by supplying a second enable signal to the inverted signal output unit. 13. The method of claim 12,
The timing controller is
A display device configured to output the first and second enable signals at an activation level when the voltage of the original signal input from the sensing unit is greater than a predetermined reference value. 13. The method of claim 12,
The timing controller is
resetting the first and second enable signals in synchronization with the pulse of the vertical synchronization signal;
A display device configured to output the first and second enable signals at the activation level during a display period in which the pixels are driven and a touch sensor driving period in which the touch sensors are driven. sensing an electromagnetic field of an original signal applied to a signal transmission line using a first non-contact coupler;
generating an inverted signal of the original signal; and
and supplying the inverted signal to a second non-contact coupler to inject an electromagnetic field of the inverted signal into the signal transmission line,
The signal transmission line includes an IC chip generating the original signal, a wiring of a printed circuit board present on the signal transmission line, and a ground surface.

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