KR20170123392A - An apparatus of control for LED electric lighting board for Flicker Reduction using Grey Image Scale and that of method for control - Google Patents

Abstract

The present invention relates to an apparatus and a method for controlling a light emitting diode (LED)-electronic display board through reduction of flicker by using a gray image scale (GIS). The apparatus for controlling an LED-electronic display board comprises: an image signal source supplying an image signal for displaying an image medium such as a digital video disc (DVD), high definition multimedia (HDMI), a display port (DP) or a videocassette recorder (VCR) on the LED electronic display board; and a GIS control part performing a control operation such that a refresh rate cycle is adjusted in accordance with a gray scale with respect to an image signal input into the image signal source to improve the refresh rate with a high gray scale and a low gray scale, and the frame frequency of an output image is adjusted to a balance uniformly distributed in a time area to display image information where flicker has been reduced. Accordingly, a GIS control is applied to the LED electronic display board using a general constant current driver integrated circuit (IC) with no support by a pulse width modulation (PWM) type-LED driver function to resolve a pigmentation phenomenon caused when a displayed image on the LED electronic display board is photographed at a high speed, thereby improving display performance by improving image quality through reduction of flicker.

Description

[0001] The present invention relates to an apparatus and a control method for a flicker-reduced LED display board using a GIS (Gray Image Scale)

More particularly, the present invention relates to an apparatus and a method for controlling a flicker-reduced LED electric signboard using a GIS (Gray Image Scale), and more particularly, to an LED display board using a general constant current driver IC, (Gray Image Scale) which improves the display performance of image quality by reducing flicker by solving the phenomenon of pigmentation during high-speed shooting of the expression image of LED display board by applying Gray Image Scale control And a control method thereof.

In addition, the present invention is configured to display a high-bit gray level using a low-bit gray scale processing circuit, thereby realizing a relatively high resolution resolution using a relatively simple and inexpensive hardware circuit. And more particularly, to a flicker-canceling LED electric signboard control device and method for increasing a gray scale bit in a driving IC by pulse width modulation (PWM) dispersion scanning.

LED (Light Emitting Diode) means a light emitting diode which is a semiconductor device emitting light, and is widely used in various electronic products such as red, green, blue, and yellow, and electronic display boards such as instrument panels.

In the LED display panel, a plurality of LEDs are arranged in a matrix form, and a plurality of LEDs arranged in a matrix form a pixel for displaying an image, so that an image can be displayed. Such LED electronic signboards are installed in various forms on the outside or inside of a building to transmit advertisements and various information.

2. Description of the Related Art Generally, a display panel system in which LEDs, compact fluorescent tubes, and the like are arrayed in a matrix form to display information such as various characters and pictures is known.

The electric signboard system receives an image signal from an AV device such as a DVD, a VCR, a broadcasting device, etc., and converts the image signal into a signal suitable for the electric signboard so that the image is displayed.

The LED electronic sign board module means that the display unit with the LED and the drive circuit unit are integrated. By arranging these LED electronic sign board modules as many as the required number of times, the electronic signboard is constituted. Generally, the outdoor electric signboard is installed in large size on the roof or outer wall of a building for advertisement effect and the like.

The outdoor display panel includes a light emitting diode (LED) display panel, a fluorescent display panel (FDT) display panel, a cathode ray tube (CRT) display panel, and a liquid crystal display (LCD) display panel.

Since the FDT electric signboard is a fluorescent discharge electric signboard, it is expensive to manufacture and difficult to manage. Recently, CRT electric signboards are cathode ray discharge type electric signboards. Like the FDT electric signboards, they are expensive to manufacture and heavy in weight. It is not. On the other hand, LCD electronic signboards are electronic signboards using liquid crystal materials and are widely used at present, but they are not only costly to manufacture but also difficult to be very large.

On the other hand, the LED electric signboard is an electric signboard using LED, and it is not only long in manufacturing cost, easy to manage, and long in life, but also is easy to make it very large, and occupies a high proportion of over 90% in outdoor electric signboards. In addition, since the LED display board uses self-luminous LEDs, it has advantages of low power consumption and very fast response time.

The driving methods of the LED display panel include a static driving method and a dynamic driving method.

In the static driving method, when an active circuit is arranged in each of the LED elements at a ratio of 1: 1, and the LED element includes a plurality of LED unit elements, the active elements are arranged in the unit elements at 1: Since each LED element or LED unit element is controlled to be turned on through the active circuit, the control is relatively easy and noise is not generated. However, since the same number of active circuits as the LED element or LED unit element must be provided, And the manufacturing cost is also high. On the other hand, in the dynamic driving method, LED groups are grouped in rows or columns, active circuits are arranged for each group, and LED groups are selected in order of arrangement through a selector so that each LED group is sequentially turned on.

That is, the dynamic driving method is a method in which the LED electric signboard is entirely scanned and illuminated for one period, and since the number of active circuits is not required more than the static driving method, the manufacturing cost is low, However, since the entire LEDs must be sequentially turned on within a short period of time, there is a problem that flickering of the black periodic line occurs when the LED electric signboard is photographed through the camera.

Therefore, when the refresh rate is increased in the dynamic driving method, the amount of image data to be displayed per unit time is increased, so flicker symptoms that can often occur in the dynamic driving method are alleviated and the image quality can be improved.

Accordingly, the present invention proposes a control device for improving the display performance of the LED electronic signboard by reducing flicker through GIS (Gray Image Scale) control.

1. LED electric signboard and its driving method (LED ELECTRIC LIGHTING BOARD AND ITS DRIVING METHOD) (Patent Registration No. 10-0992383) 2. Description of the Related Art [0002] An image data display method in which a refresh rate is improved in order to reduce a flicker phenomenon, and a dynamic light emitting diode (LED) display panel control apparatus using the dynamic light emitting diode display panel (Patent Registration No. 10-1237950) 3. AC Direct Connection Type LED Lighting Device Having Flicker Reduction and Light Efficiency Improvement Function (Patent Application No. 10-2010-0104362) Having Function of Flicker Reduction and Improving Light Efficiency

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide an LED display using a general constant current driver IC in which a PWM type LED driver function is not supported by using a GIS (Gray Image Scale) And to provide a flicker-reduced LED electric signboard control apparatus and a control method using a GIS (Gray Image Scale) which improves the display performance of image quality improvement by eliminating the pigment deposition phenomenon by reducing flicker.

In addition, the present invention is configured to display a high-bit gray level using a low-bit gray scale processing circuit, thereby realizing a relatively high resolution resolution using a relatively simple and inexpensive hardware circuit. And to provide a flicker-reduced LED electric signboard control device and method for increasing a gray scale bit in a driving IC by pulse width modulation (PWM) dispersion scanning.

However, the objects of the present invention are not limited to the above-mentioned objects, and other objects not mentioned can be clearly understood by those skilled in the art from the following description.

In order to achieve the above object, a flicker-reduced LED electric signboard control apparatus using a GIS (Gray Image Scale) according to the first embodiment of the present invention is configured to display an image medium such as DVD, HDMI, DP or VCR on an LED display board A refresh rate of a gray scale and a refresh rate of a low gray scale are improved by adjusting a refresh rate cycle according to a gray scale in a video signal source for supplying a video signal and a video signal inputted to a video signal source, And a GIS controller for controlling the frame frequency of the output image to control the flicker-reduced image information to be displayed.

According to an additional feature of the present invention, the LED billboard of the flicker-reduced LED display board using the GIS (Gray Image Scale) receives the video signal input from the video signal source and drives each light source of the LED display board module A generation control unit for generating a driving current to generate a driving current for controlling a frame rate of a video image input from the frame memory, a gray scale control unit for controlling a frame rate of an image to be output, And a gray scale clock suitable for a gamma correction unit and a gray scale bit conversion logic for converting a refresh rate according to a gray scale adjusted through the GAIN control unit into a target gray level bit source image signal, A control unit for controlling the data clock and the horizontal synchronization signal, and a space conversion unit for generating a synchronization signal, The GIS control unit and the GIS control unit display the ratio of the number of pixels to the number of pixels of the image signal generated and transmitted in synchronization with the gamma correction and the synchronization, thereby making the distribution of brightness and shade uniform. Histogram Equalization A flicker detection unit for detecting a flicker frequency generated for an integer multiple of a cycle in which integration time is input for the uniform noise adjusted through the histogram equalization and adjusting integration time, And an integration time setting unit for setting the detected Flick frequency according to the occurrence of the flicker and the Integration time time that is adjusted and transmitted to the LED display panel module unit.

At this time, according to an additional feature of the present invention, the GAIN control unit of the flicker-reduced LED electric signboard control apparatus utilizing a GIS (Gray Image Scale) adjusts the refresh rate to a high gray scale, Since the scale has no effect on the refresh rate, the high gray scale increases the refresh rate by a multiple of the divisions, which increases the frame frequency of the output image inefficiently. Therefore, the image is smoothly processed by lowering the gray scale of the output image. .

In order to accomplish the above object, a flicker reduction LED display panel control method using a GIS (Gray Image Scale) according to a second embodiment of the present invention includes: A driving current is generated for driving, a frame memory unit stores an image inputted in a frame unit, a GAIN control unit adjusts a low gray scale for a type of input image information and a refresh rate to set a frame frequency of a high- ; A gray scale clock suitable for the Gray scale bit conversion logic and a data clock for transmission are used for converting the adjusted refresh rate according to the gray scale adjusted by the GAIN control unit into the gradation bit source image signal of the target value from the gamma correction unit, A second step of generating a control signal and a synchronization signal such as a horizontal synchronization signal; A third step of dividing the brightness value concentrated in one place by smoothing the brightness value distribution by displaying the ratio of the number of pixels to the number of pixels of the transmitted image signal generated by the gamma correction and synchronization in the histogram equalization as a function; And a fourth step of detecting whether the integration time is an integer multiple of the input period, detecting the Flick frequency, adjusting the integration time, and transmitting the converted video signal to the LED display panel module in consideration of the transmitted set period time to display the corresponding video signal .

The flicker-reduced LED display panel control device and the control method using the GIS (Gray Image Scale) according to the embodiment of the present invention can be applied to an LED display panel using a general constant current driver IC, Scale control is applied to solve the pigmentation phenomenon at the time of high-speed photographing of the display image of the LED electronic signboard, thereby improving the display performance of image quality improvement by reducing the flicker.

In addition, the flicker-canceled LED electric signboard control apparatus and control method using a GIS (Gray Image Scale) according to an embodiment of the present invention can display a high-bit tone by using a low-scale gray scale processing circuit (PWM) by using a relatively simple and inexpensive hardware circuit to implement a relatively high resolution resolution. By increasing gray scale bits in a driving IC by distributed scanning, it reduces flickering due to imaging can do.

In addition, the flicker reduction LED electronic billboard control apparatus and control method using GIS (Gray Image Scale) according to the embodiment of the present invention solves the pigment deposition phenomenon easily captured at the time of high-speed photographing of the display image, and at the same time, Scale refresh rate and can support refresh rate enhancement applied to OE signal precision control technology and GIS clock control technology, non-sequential grayscale technology, and grayscale supplement technology.

In addition, the flicker-reduced LED display panel control method and the control method using the GIS (Gray Image Scale) according to the embodiment of the present invention adjusts the width of the OE signal to 8 ns precisely so as to adjust the smallest OE pulse width to 8 ns The error of the gray level OE pulse width can be adjusted to 8 ns, so that the OE pulse width is configured not to be connected to the DCLK CLOCK cycle, thereby replacing the batch line signal of the small pulse width OE to increase the blanking time, It can also be applied to displays.

1 is a system configuration diagram of a flicker-reduced LED electronic signboard using a GIS (Gray Image Scale) according to the present invention
FIG. 2 is a detailed block diagram of a flicker-reduced LED electric signboard control apparatus utilizing a GIS (Gray Image Scale)
FIGS. 3 to 4 are cross-sectional views of a flicker-reduced LED display panel using a GIS (Gray Image Scale)
5 to 6 are internal block diagrams showing a GIS (gray image scale) control driving method according to the present invention
FIG. 7 is a flowchart illustrating a flicker-reduced LED display panel control procedure using a GIS (Gray Image Scale) according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a detailed description of preferred embodiments of the present invention will be given with reference to the accompanying drawings. In the following description of the present invention, detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

In the present specification, when any one element 'transmits' data or signals to another element, the element can transmit the data or signal directly to the other element, and through at least one other element Data or signal can be transmitted to another component.

In general, a 16-bit gray scale driver IC is used to process a 16-bit gray scale by the PWM method. The 16-bit gradation process refers to subdividing the step of the brightest gradation level in the darkest gradation level into the 16th power of 2, that is, the gradation level of 65,536 gradations. In the image display of the LED electric sign board, And chromaticity are reproduced so as not to be stained, and the density of pixels can be increased to realize a high resolution image quality

A gradation driver IC using a pulse width modulation (PWM) method has been developed and commercially available in order to realize a gray scale level. There are many kinds of commercially available gradation driver ICs ranging from 8-bit gradations to 16-bit gradations. The 8-bit gradation driver IC allows gradation to be expressed over 256 gradation levels of 8 grades of 2, The IC is capable of gradation representation over the gradation levels of 65,536 steps of 16 approvals of 2. Therefore, the higher the bit, the more the number of gradation levels sharply increases, and thus the higher gradation image processing is possible.

FIG. 1 is a system configuration diagram of a flicker-reduced LED electric signboard using a GIS (Gray Image Scale) according to the present invention, and includes a video signal source 100 and an electric sign board 200. The image signal source 100 provides an image signal to the LED display panel 200. The electric sign board 200 receives the image signal and displays the image.

The image signal source 100 is a device for supplying a video signal to be displayed on the LED display panel 200 and may be a device for reproducing an image medium such as a DVD, HDMI, DP or VCR, But it is not limited thereto.

The LED display panel 200 includes a plurality of unit video display devices arranged in a matrix to display a video on a screen based on a video signal received from the video signal source 100.

Meanwhile, the image display device can be largely classified into a static method and a dynamic method according to the driving method of the LED electric sign board module. In the static method, each light source constituting the LED electric sign board module is individually controlled And a dynamic method is a method of displaying images by driving only some light sources at one time and driving other light sources sequentially or not sequentially without driving all the light sources constituting the LED electric sign board module at once.

FIG. 2 is a detailed block diagram of a flicker-reduced LED electric signboard control device using a GIS (Gray Image Scale), and FIGS. 3 to 4 show a flicker-reduced LED signboard control device using a GIS (Gray Image Scale) Fig. Referring to FIGS. 1 to 4, the detailed configuration and operation of the flicker reduction LED display panel will be described. The GIS controller 210 adjusts a refresh rate cycle according to the gray scale to the image signal input to the image signal source 100 By enhancing the refresh rate of the high gray scale and low gray scale, the ballast which is evenly distributed in the time domain is captured and the frame frequency of the output image is adjusted to reduce the flicker of the pigment deposition phenomenon.

The GIS control unit 210 includes a main control unit 211, a frame memory 213, a GAIN control unit 215, a gamma correction unit 217, and a space conversion unit 219. In the video signal source 100, The main controller 211 receives the video signal from the main controller 211 and generates driving currents for driving the light sources of the LED display module 260 based on the video signals. And the GAIN controller 215 adjusts the frame rate of the output image by adjusting the refresh rate to a low gray scale with respect to the type of the input image information.

Thereafter, the gamma correction unit 217 converts the adjusted refresh rate according to the adjusted gray scale through the GAIN control unit 215 into a gradation bit source image signal of a target value, and a space scale unit 219 converts the gradation bit source image signal to a gray scale ) Generates a grayscale clock suitable for the bit conversion logic and a control and synchronization signal such as a data clock and a horizontal synchronization signal for transmission.

Thereafter, in the histogram equalization 230, the ratio of the number of pixels to the number of pixels of the image signal generated and transmitted by the gamma correction and synchronization in the GIS controller 210 is displayed as a function to equalize the distribution of lightness and darkness, Divide the values so that they are smoothed.

The uniform noise adjusted through the histogram equalization 230 is transmitted to the flicker detecting unit 240. The flicker detecting unit 240 operates to generate a flicker if the integration time is not an integral multiple of the input period The flicker detection unit 240 detects the flick frequency and adjusts the integration time.

The flick frequency and the adjusted integration time detected in accordance with the flicker generation period are transmitted to the intergration time setting unit 250 according to the period inputted by the flicker sensing unit 240, And the corresponding image signal is displayed. As a result, the flicker for the pigment deposition phenomenon is displayed according to the time and period flow.

On the other hand, the probability density function of the uniform noise through the histogram equalization (230)

The average (μ) and variance (σ²) of these densities are as follows.

This probability density function is expressed as a uniform noise as follows.

That is, the GAIN control unit 215 adjusts the refresh rate to a high gray scale, and when the gray scale has a high gray scale, the gray scale does not affect the refresh rate. Therefore, the high gray scale is divided by the refresh rate Since the frame frequency of the output image becomes ineffectually ineffective, the gray scale of the output image is lowered, and the image is smoothly processed to obtain the image quality improvement effect.

5 illustrates an internal block diagram illustrating a GIS (Gray Image Scale) control driving method according to the present invention in which a video signal transmitted from the video input source 100 is supplied to a flicker The GIS control unit 210 sets a 3-digit bright gray level as a default value, and outputs the 3-digit gray level as a default value to the LED display unit 260. [ , The number of gray levels to be dispersed is distributed, and some of the lighter gray level sections are divided into 8 equal parts to disperse and display, thereby improving the screen output speed of the gray level so that the partial gray level screen output is increased 8 times By improving the output speed, the visual effect and the quality of the shooting effect can be increased.

In addition, the gray scale can be implemented as 8192/16384/32768/65536, so that the gray scale effect according to the number of gray levels is supported, the output requirements of different LED display boards can be satisfied, and the memory R / W Minimizes the luminance loss by minimizing the interval between the timing signal and the OE signal.

Also, LED control devices typically require OE pulse widths to match the DCLK CLOCK cycle, and for smaller OE pulse widths, the DCLK CLOCK frequency must be raised, which further complicates the circuit design of the LED display, The GIS control apparatus of the present invention adjusts the width of the OE signal to 8 ns so that the smallest OE pulse width is 8 ns and the error of each gray level OE pulse width is 8 ns So that the OE pulse width is configured not to be connected to the DCLK CLOCK cycle so that the 8ns OE pulse width does not necessarily reach DCLK 8ns / frequency and need to be 125MHz and the provided 32ns pulse width also reaches DCLK 8ns / It does not need to be 31.25 MHz. Therefore, by substituting the placement row signal of the small pulse width OE to increase the blanking time, the present invention can be applied not only to a static display but also to a scanning display.

The GIS controller according to the present invention solves the pigment deposition phenomenon easily captured at high speed photographing of the LED image display board and at the same time, it improves the refresh rate of the high grayscale and low gray scale. The OE signal precision control technology and the GIS clock control Increased refresh rates applied to the technology, non-sequential grayscale technology, and grayscale supplement technology.

FIG. 7 is a flowchart illustrating a flicker reduction LED display control process using a GIS (Gray Image Scale) according to the present invention. Referring to FIGS. 1 to 7, First, a driving current is generated to drive each light source of the LED display module 260 with respect to an image signal transmitted from the image signal source 100 (step S100)

The image input from the frame memory unit 213 is stored in units of frames and the GAIN controller 215 adjusts the frame frequency of the output image by adjusting the refresh rate to a low gray scale with respect to the type of the input image information. (Step S200)

The gamma correction unit 217 converts the adjusted refresh rate according to the adjusted gray scale through the GAIN control unit 215 into the target gray-level bit source image signal (refer to step S300) A gray scale clock suitable for Gray scale bit conversion logic and a data clock and horizontal synchronization signal for transmission and a synchronization signal are generated in operation S400.

 The ratio of the number of pixels to the number of pixels of the transmitted image signal generated by the gamma correction and synchronization in the histogram equalization (230) is displayed as a function so as to equalize the distribution of brightness and darkness so that the brightness and darkness concentrated in one place are divided and smoothed. Step S500)

It is configured to detect whether the integration time is an integer multiple of the input period, detect the flick frequency, adjust the integration time, and transmit it to the LED display panel module 260 in consideration of the transmitted set period time to display the corresponding video signal. (Step S600)

As described above, preferred embodiments of the present invention have been disclosed in the present specification and drawings, and although specific terms have been used, they have been used only in a general sense to easily describe the technical contents of the present invention and to facilitate understanding of the invention , And are not intended to limit the scope of the present invention. It is to be understood by those skilled in the art that other modifications based on the technical idea of the present invention are possible in addition to the embodiments disclosed herein.

100: video signal source
200: LED display board
210: GIS control unit 211:
213: frame memory 215: GAIN control section
217: Gamma correction unit 219: Space conversion unit
230: Histogram Equalization 240: Flicker detection unit
250: integration time setting unit 260: LED electric sign board module unit

Claims (4)

A video signal source 100 for supplying a video signal such as a DVD, HDMI, DP, or VCR to a video signal to be displayed on the LED display board,
The refresh rate of the image signal input to the image signal source 100 is adjusted according to the gray scale so as to improve the refresh rate of the high gray scale and low gray scale so as to capture the ballast evenly distributed in the time domain, And a GIS controller (210) for controlling the display of the reduced flicker-reduced image information by adjusting the frame frequency. The flicker reduction LED display board (200) using the GIS (Gray Image Scale) Device. The method according to claim 1,
The LED billboard 200 is
A generation controller 211 for receiving a video signal input from the video signal source 100 and generating a driving current for driving each light source of the LED display module,
A GAIN control unit 215 for controlling the frame frequency of the image stored in the frame memory 213 in units of frames and adjusting the refresh rate to a low gray scale with respect to the type of the input image information,
A gamma correction unit 217 for converting the adjusted refresh rate according to the adjusted gray scale through the GAIN control unit 215 into a gradation bit source image signal of a target value,
A GIS control unit 210 including a gray scale clock suitable for gray scale bit conversion logic, a spatial conversion unit 219 for generating a control signal of a data clock and a horizontal synchronization signal for transmission and a synchronization signal,
A histogram equalization (smoothing) process is performed by dividing the intensity value concentrated in one place by uniformly distributing the lightness value distribution by displaying the ratio of the number of pixels to the number of pixels with respect to the number of pixels generated by the gamma correction and synchronization in the GIS controller 210 230),
A flicker detection unit 240 for detecting a flicker frequency generated for an integer multiple of a period in which integration time is input for the uniform noise adjusted through the histogram equalization and adjusting integration time,
An integration time setting unit 250 for setting a Flick frequency detected according to a flicker generated by the flicker sensing unit 240 and an integration time adjusted and transmitted to the LED display board 260, And a control unit for controlling the flicker reduction LED display board using the GIS (Gray Image Scale). 3. The method of claim 2,
The GAIN control unit 215 adjusts the refresh rate to a high gray scale, and when the gray scale has a high gray scale, the gray scale does not affect the refresh rate. Therefore, the high gray scale is divided into multiple times The frame frequency of the output image is increased ineffectively, so that the gray scale of the output image is lowered to smoothly process the image, thereby controlling the flicker reduction LED display board using the GIS (Gray Image Scale). A driving current is generated to drive each light source of the LED electric sign board module 260 with respect to an image signal transmitted from the image signal source 100 and the image inputted from the frame memory unit 213 is stored frame by frame, A first step of setting a frame frequency of an image to be output at a high level by adjusting a refresh rate to a low gray scale with respect to a type of input image information;
The gamma correction unit 217 converts the adjusted refresh rate according to the adjusted gray scale through the GAIN control unit 215 into a gradation bit source image signal of a target value and outputs a grayscale clock suitable for the gray scale bit conversion logic A second step of generating a control signal and a synchronization signal of a data clock and a horizontal synchronization signal for transmission;
The third step is to divide and smooth the intensity values concentrated in one place by displaying the ratio of the number of pixels to the number of pixels of the transmitted image signal generated by the gamma correction and synchronization in the histogram equalization (230) ; And
A fourth step of detecting the flick frequency by checking whether the integration time is an integer multiple of the inputted integration period, adjusting the integration time, and transmitting the converted integration period to the LED electric sign board module 260 to display the corresponding image signal The method of controlling a flicker reduction LED display board using a GIS (Gray Image Scale).

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