KR101741097B1

KR101741097B1 - Rotating type led signboard and operation method

Info

Publication number: KR101741097B1
Application number: KR1020150051823A
Authority: KR
Inventors: 이승호; 임영식
Original assignee: 한밭대학교 산학협력단
Priority date: 2015-04-13
Filing date: 2015-04-13
Publication date: 2017-05-30
Also published as: KR20160122324A

Abstract

A rotative display device and an operation method thereof are disclosed. An FPGA board for reading the vertical line data of the moving image and outputting the vertical line data in synchronization with the frame rate of the moving image, a light emitting unit for driving the LED with the vertical line data, . Therefore, since the video is displayed by rotating the LED, the video can be displayed with low power consumption.

Description

TECHNICAL FIELD [0001] The present invention relates to a rotary type display device and a method of operating the same,

BACKGROUND OF THE INVENTION 1. Field of the Invention [0002] The present invention relates to a rotatable display device and an operation method thereof, and more particularly, to a rotatable display device that rotates an LED to display a moving image, and an operation method thereof.

The LED display uses low voltage to use the LED as a light source instead of a conventional bulb or neon, so it is safe, light, durable and has a long life. Especially, since the energy consumption is only one tenth of the conventional incandescent lamp, it is widely watched as a next generation electric signboard to replace the existing electric signboard because of low maintenance cost. In the early days of development, these LED signboards recorded only simple text, but with the introduction of wireless network technology and image software technology, they are being developed into a composite product with designs that harmonize with sound, lighting and environment. And high-quality images are being implemented.

On the other hand, the LED display panel is classified into outdoor use and indoor use depending on the application, and it is divided into a video screen for full-color use and a text and graphic oriented display using monochromatic or tri-color. LED display boards are used around us for various purposes, but they have the following disadvantages. First, the most common way to use it now, and most commonly seen around, is that ordinary LED signboards no longer attract people's attention. Secondly, since the LED screen is a two-dimensional plane, all images can be seen only from the front side, and all advertisement screens of the electric signboard can not be seen from the side or the back side. Third, the LED display consists of a large number of LEDs, and consumes the same power for the number of LEDs regardless of their size. A high resolution LED display requires high power consumption.

Korean Patent Publication No. 10-2007-0059027 (published on Jun. 11, 2007) Korean Patent Publication No. 10-2008-0065013 (published on July 11, 2008).

SUMMARY OF THE INVENTION It is an object of the present invention to solve the problems described above and provide a display device and a method of operating the same.

According to an aspect of the present invention, there is provided a base plate including a base plate as a non-circular body, two base blocks fixedly coupled to the base plate, a support block interconnecting the two base blocks, A main body including a housing and installed on the ground, a rotation block rotatably installed in the support block and formed into a cylindrical shape, a rotation plate formed in a disk shape and connected to the rotation block, A rotating body including a bearing for smoothly rotating a rotating body and a bar type having a rotation center coinciding with a rotation center of the rotating block and spaced apart from the rotation center of the rotating body at a predetermined interval The upper surface of the rotating plate of the rotating body A plurality of rotation frames installed to extend upward in the longitudinal direction and spaced apart from each other by 90 degrees in the circumferential direction of the rotation plate, a plurality of rotation frames, A support frame formed in a circular rim shape, a light emitting portion provided in at least one of the plurality of rotation frames and emitting light in accordance with an input signal, a light emitting portion located between the plurality of rotation frames, And a flange connecting the upper end of the outer housing and the upper end of the inner housing so as to support the inner housing, the outer housing being made of a transparent material, Including receipts,
An FPGA board for reading the vertical line data of the moving image and outputting the vertical line data in synchronization with the rotation speed of the LED and the frame rate of the moving image, And a motor for rotating the light emitting unit at the rotation speed,
Wherein the plurality of rotation frames are arranged at different distances from each other at a rotation center so that a space is formed by the rotation frame during rotation,
An external display and an internal display are constituted by rotating frames disposed at different distances from the center of rotation and driven by an external electric signboard and an internal electric signboard,
Further comprising a black panel provided between the light emitting unit and the rotation frame to improve a contrast ratio,
The reproducing unit performs inverse gamma correction for converting a linear brightness characteristic and corrects image data using an error diffusion method to reduce a phenomenon of low gradation luminance reduction caused by inverse gamma correction,
Wherein the FPGA board is configured to perform inverse gamma correction for converting a linear luminance characteristic and to correct image data using an error diffusion method to reduce a phenomenon of low gradation luminance reduction caused by inverse gamma correction A typical display device is provided.

Here, it further includes a server for data communication with the playback apparatus to provide a moving image.

In this case, a server for data communication with the playback apparatus and providing a moving image is further included.

The display device further includes a display for outputting an advertisement image inside the display device.

According to another aspect of the present invention, there is provided a method of manufacturing a semiconductor device including a base plate which is a non-circular body, two base blocks fixedly coupled to the base plate, a support block interconnecting the two base blocks, A main body including a cover housing and installed on the ground; a rotation block rotatably installed in the support block and formed into a cylindrical shape; a rotation plate formed in a disk shape and connected to the rotation block; And a bar type which includes a bearing for smoothly rotating the rotary body and has a rotation center of the rotary block and a bar type coinciding with each other, So that the rotation of the rotating plate A plurality of rotation frames which are installed to extend upward on the edge of the surface and spaced apart from each other by 90 degrees in the circumferential direction of the rotation plate, A support frame formed in a circular rim shape, a light emitting portion provided in at least one of the plurality of rotation frames and emitting light in accordance with an input signal, a light emitting portion located between the plurality of rotation frames, And a flange connecting the upper end of the outer housing and the upper end of the inner housing so as to support the inner housing, the outer housing being made of a transparent material, Including receipts,
An FPGA board for reading the vertical line data of the moving image and outputting the vertical line data in synchronization with the rotation speed of the LED and the frame rate of the moving image, And a motor for rotating the light emitting unit at the rotation speed,
Wherein the plurality of rotation frames are arranged at different distances from each other at a rotation center so that a space is formed by the rotation frame during rotation,
An external display and an internal display are constituted by rotating frames disposed at different distances from the center of rotation and driven by an external electric signboard and an internal electric signboard,
Further comprising a black panel provided between the light emitting unit and the rotation frame to improve a contrast ratio,
The reproducing unit performs inverse gamma correction for converting a linear brightness characteristic and corrects image data using an error diffusion method to reduce a phenomenon of low gradation luminance reduction caused by inverse gamma correction,
Wherein the FPGA board is configured to perform inverse gamma correction for converting a linear luminance characteristic and to correct image data using an error diffusion method to reduce a phenomenon of low gradation luminance reduction caused by inverse gamma correction A method of operating a rotatable display device using a typical display device,
A step of reading the image data corresponding to the vertical column, a step of converting the image data corresponding to the vertical column into the serial data, and transmitting the serial data to the LED driver in synchronization with the rotational speed and the frame rate of the image data Step.

Here, the step of correcting includes performing the inverse gamma correction for converting the linear brightness characteristic and correcting the image data using the error diffusion method to reduce the low gradation brightness reduction phenomenon caused by the inverse gamma correction do.

In this case, the step of reading includes storing the image data of the frame inputted in the horizontal row in accordance with the input order, and reading the image data corresponding to the vertical row.

At this time, the transmitting step includes converting the image data corresponding to the rotational position into serial data, and transmitting the serial data to the LED driver while performing the shift operation.

When the rotary display device and the operation method of the present invention as described above are used, the moving picture is displayed by rotating the LED, so that the moving picture can be displayed with low power consumption.

1 is a perspective view schematically showing a rotatable display device according to an embodiment of the present invention.
2 is a perspective view schematically showing a part of a rotatable display device according to an embodiment of the present invention.
3 is a front view schematically showing a part of a rotatable display device according to an embodiment of the present invention.
4 is a cross-sectional view schematically showing a cross-section of a rotatable display device according to an embodiment of the present invention.
5 is a cross-sectional view schematically showing a cross-section of a rotatable display device according to another embodiment of the present invention.
6 is a block diagram illustrating a control circuit configuration of a rotatable display device according to a first embodiment of the present invention.
7 is a block diagram showing a control circuit configuration of a rotation type display device according to a second embodiment of the present invention.
FIG. 8 is a flowchart illustrating an operation method of a rotatable display device according to an embodiment of the present invention.
9 is a flowchart of an inverse gamma correction and error diffusion step according to an embodiment of the present invention.
Fig. 10 shows a nonlinear characteristic of the luminance displayed on the input signal of the CRT.
Figure 11 shows the problem of gradation representation caused by inverse gamma correction.
12 is a flowchart illustrating an error diffusion method according to an embodiment of the present invention.
13 is a flowchart of the block interleaving step according to an embodiment of the present invention.
Fig. 14 is an exemplary diagram showing a video signal on a monitor. Fig.
15 is a diagram illustrating the number of rotations of an LED direct frame image.
16 is a diagram illustrating the number of rotations and the number of images.
FIG. 17 is a diagram illustrating an example in which when the number of LED bars is two, only the half of the frame information is displayed.
18 is a diagram illustrating a process of storing data for the first one frame and outputting the stored data for two frames.
FIG. 19 is a flowchart of a step of outputting a video data serial according to an embodiment of the present invention.
20 is an exemplary view showing a moving image output from the rotation type display device.

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

1 is a perspective view schematically showing a rotatable display device according to an embodiment of the present invention in one direction. 2 is a perspective view schematically showing a part of a rotatable display device according to an embodiment of the present invention in another direction. 3 is a cross-sectional view schematically showing a rotary display device according to an embodiment of the present invention in one direction. And FIG. 4 is a cross-sectional view schematically showing a cross-section of another embodiment of the rotatable display device according to the present invention.

The rotating display device according to the present embodiment may include a main body 110, a rotating body 120, a rotating frame 130, a light emitting portion 140, and a receiving portion.

The main body 110 may be mounted on the ground to support the rotating body 120, the rotating frame 130, and the like. Specifically, the main body 110 includes a base plate 111, a base plate 111, a base block 112 fixed to the base plate 111 and two base blocks 112 fixed to the base plate 111, And a support block 113 coupled to the rotation body 112 and to which a rotation body 120 described later is rotatably coupled. The support block 113 may have a circular opening into which the rotating body 120 is inserted.

The main body 110 may further include a cover housing 114 coupled to the base plate 111 and surrounding the base block 112 and the like. The cover housing 114 may be substantially similar to the base plate 111. For example, the cover housing 114 may be cylindrical in shape similar to the disc-shaped base plate 111.

The main body 110 may include a driving unit 240. The driving unit 240 may include a BLDC motor, and may be installed on the base plate 111 of the main body 110. However, the present invention is not limited thereto.

The rotating body 120 may be rotatably installed in the main body 110. For example, the rotating body 120 may include a rotating plate 121 having a disk shape and a cylindrical rotating block 122 provided on a bottom surface of the rotating plate 121. Here, the rotation block 122 may be rotatably installed in the support block 113 described above. The rotation block 122 is cylindrical, and its center of rotation can coincide with the center of rotation of the rotation plate 121. The rotation block 122 may serve as a pulley.

Accordingly, the rotating body 120 may be rotatably installed on the main body 110. [ At this time, a bearing or the like may be further provided between the rotating body 120 and the main body 110 to facilitate rotation.

The rotating body 120 can be rotated by the driving unit 240. For example, the rotary display apparatus may further include a power transmitting unit 170 connecting the driving unit 240 and the rotating body 120. Specifically, the power transmitting unit 170 may include a rotating block 122 serving as a pulley and a belt surrounding an axis of the motor. The power transmitting unit 170 may include gears that connect the rotating body 120 and the driving unit 240. [

The rotating frames 130 are formed of a plurality of rotating bodies 120. The rotating frames 130 may be spaced apart from each other by a predetermined distance from the center of rotation. Specifically, the rotary frame 130 is of a bar type and may be installed to extend upward from the edge of the rotary plate 121. The plurality of rotation frames 130 may be spaced apart from each other at the same distance from the center of rotation so as not to generate eccentricity. However, the present invention is not limited thereto, and the plurality of rotating frames 130 may be spaced apart to form a space therein during rotation.

For example, the plurality of rotation frames 130 may be installed so as to extend upwardly on the upper surface edge of the rotation plate 121 as shown in FIG. The plurality of rotation frames 130 may be disposed at 90 degrees from the center of rotation.

On the other hand, since the lower ends of the plurality of rotary frames 130 are fixed, they can be bent outward by the centrifugal force. The rotary type display device may further include a support frame 131 connecting the plurality of rotation frames 130 to prevent the rotation frame 130 from being bent. For example, the support frame 131 may be respectively coupled to the upper portions of the plurality of rotation frames 130 in a circular rim shape.

The light emitting unit 140 is installed in at least one of the plurality of rotation frames 130, and can emit light according to an input signal. For example, the light emitting unit 140 may include an LED module. The LED module may include a plurality of LED elements. All kinds of light emitting devices can be applied to such an LED device, and red (R), green (G), and blue (B) light sources may be included.

The rotating type display device may further include a black panel 180 disposed between the light emitting unit 140 and the rotating frame 130 to improve the contrast ratio.

The receiving portion may be located in a space formed as the plurality of rotating frames 130 rotate. Specifically, the receiving portion includes an inner housing 150 made of a light-transmitting material, and the inner housing 150 is positioned between the plurality of rotating frames 130 and can have an opening for receiving the article. For example, the inner housing 150 may be a cylindrical housing with an open top.

Referring to FIG. 1, the inner housing 150 may be coupled to the rotating body 120 or may be coupled to the main body 110. Or may be coupled to an outer housing 160 that is supported on the main body 110 as described below. Hereinafter, the case where the inner housing 150 is coupled to the outer housing 160 will be described, but the present invention is not limited thereto.

The outer housing 160 may wrap the rotating frame 130. For example, the outer housing 160 may have a cylindrical shape with an open top and a bottom. The outer housing 160 and the inner housing 150 may be coupled to each other at a position that does not interfere with the rotation frame 130. Specifically, the upper end of the outer housing 160 and the upper end of the inner housing 150 may be engaged. The rotating display device may further include a flange 190 connecting the outer housing 160 and the inner housing 150.

Since the plurality of rotation frames 130 are bar type and are spaced apart from each other as described above, the light emitting unit 140 can provide a semi-transparent image when rotated. That is, the viewer can view not only an image by the light emitting unit 140 but also an object placed in the storage unit.

Accordingly, the display device of the present invention is configured such that a jewel or the like is placed inside the light emitting unit 140 for displaying an image, and the image and the product of the light emitting unit 140 are viewed together, The effect can be increased. 5 is a cross-sectional view schematically showing a rotatable display device according to another embodiment of the present invention. The rotary display device according to this embodiment is the same as or similar to the rotary display device according to the above-described embodiment. Therefore, redundant description will be omitted.

According to the present embodiment, the rotative display device may further include a power source unit 220, a moving image playback unit 210, and a slip ring 230.

The power supply unit 220 is installed in the main body 110 and can supply electric energy to the moving picture reproducing unit 210. For example, the power supply unit 220 may receive electric energy from the outside, transform it and / or convert it, and transmit it to the moving image playback unit.

The moving picture reproducing unit 210 can transmit a video signal to the light emitting unit 140. [ That is, the moving picture reproducing unit 210 may be electrically connected to the light emitting unit 140 to output a video signal to the light emitting unit 140. The moving picture playback unit 210 may include a playback device 211 and an FPGA board 212 for reading and outputting vertical line data of a moving image. The playback apparatus 211 may further include a processor and a memory. Here, the memory stores the operating system and programs. The operating system may provide an operating environment for executing the program.

The moving picture playback unit 210 may receive the video data, but may further include a connector or the like. Or the moving image playback unit 210 may receive image data using a wireless communication network such as WIFI.

The moving picture reproducing unit 210 may be installed in the rotating body 120. More specifically, the moving image playback unit 210 may be fixedly installed on the rotation plate 121.

The power source unit 220 and the moving image playback unit 210 may be electrically connected through an electric wire or the like. Since the power source unit 220 is fixed and the moving image playback unit 210 rotates together with the rotation body 120, the slip ring 230 electrically connects the power source unit 220 and the moving image playback unit 210 .

The slip ring 230 is an electrical / mechanical part, also called a rotary joint, a rotary connector, or the like, and is a rotary connector that can be transmitted without twisting the wire when power or signal lines are supplied to the rotating equipment.

The slip ring 230 may be installed under the rotating body 120. Specifically, the slip ring 230 may be installed inside the rotation block 122 or may be installed below the rotation block 122. [

Therefore, the rotating display device according to the above-described embodiment includes the motion picture reproducing unit 210 inside the rotating body, so that the space can be efficiently used.

The mechanism configuration of the rotary type display device has been described. Hereinafter, the configuration of the control circuit of the rotary type display device will be described.

6 is a block diagram illustrating a control circuit configuration of a rotatable display device according to a first embodiment of the present invention.

The control circuit of the rotating display device 600 includes a playback device 610 for playing back a moving image, vertical line data of a moving image, and vertical line data in synchronization with the frame rate of the moving image An FPGA board 620, a light emitting unit 630 for driving the LED with vertical line data, and a motor 640 for rotating the light emitting unit 630 at a rotational speed, and the reproducing apparatus 610 includes a processor and a memory . Memory stores the operating system and programs. The operating system provides an operating environment for executing the program. The program is executed by the processor to cause the rotating display device 600 to operate.

The processor 610 executes the execution code of the memory, the memory stores the execution code and data, the reproduction apparatus 610 reproduces the moving image, the FPGA board 620 reads the vertical line image data from the moving image, And outputs the converted signal to the light emitting unit 630. The light emitting unit 630 drives the LED with the serial data. One embodiment of the rotatable display device 600 constructed based on such a device configuration is as follows.

The reproducing apparatus 610 corrects the image data using the inverse gamma correction and error diffusion method. Reproducing apparatus 610 performs inverse gamma correction for converting the linear luminance characteristic. The reproducing apparatus 610 corrects the image data using an error diffusion method to reduce the phenomenon of low gradation luminance reduction caused by inverse gamma correction. In another embodiment, the FPGA board 620 may perform image data correction by the programmed logic instead of the playback apparatus 610. [

The FPGA board 620 stores image data of a frame input in a row in accordance with the input order. The FPGA board 620 reads the image data corresponding to the vertical column. The FPGA board 620 converts the image data corresponding to the rotational position into serial data. The FPGA board 620 transmits the serial data to the light emitting unit 630 while performing the shift operation.

The light emitting unit 630 drives the LEDs with serial data. The motor 640 rotates the light emitting unit 630. The line image driven by the light emitting unit 630 is displayed as a moving image of a circular shape due to the afterimage effect.

In another embodiment, the rotative display device 600 may further include an internal display for outputting an advertisement image therein. The rotary display device 600 can output moving images by rotating the light emitting unit 630 of the internal display. The internal display can read and output the advertisement image from the playback apparatus. The advertisement image displayed on the internal display is superimposed on the moving picture of the rotatable display device 600. [ The internal display can be displayed by increasing the luminance of the advertisement image. The videos displayed on the two displays can be associated with each other to provide a unique display effect. The internal display may be a rotatable display device. At this time, the motors 640 are respectively disposed on the upper and lower sides to drive the external electric sign board and the internal electric sign board.

7 is a block diagram showing a control circuit configuration of a rotation type display device according to a second embodiment of the present invention.

The playback apparatus 710 describes a configuration necessary for data communication with the server 720 to download a moving image.

The playback apparatus 710 includes a communication module 711 for data communication with the server 720. The server 720 includes a web server 721 for connecting to the Internet, a data server 722 for processing data, And a database 723 for storing the contents of the database 723. The components will be sequentially described as follows.

The communication module 711 of the playback apparatus 710 communicates data with the server 720 to download a moving image. The playback apparatus 710 receives the moving picture list from the server 720 after the authentication process. The playback apparatus 710 downloads the selected video from the video list. The playback apparatus 710 can download all of the moving picture files recorded in the moving picture list before playing them. The playback apparatus 710 compares the current date and time according to the scenario, and reproduces a moving image to be played back. The playback apparatus 710 sets a moving picture list and a scenario, downloads a moving picture from the server 720 according to the set environment, and plays it at a designated time. The video list is a file in which a video file name is stored, and the scenario is a file in which a video file is to be reproduced by setting a date and time.

The server 720 includes a web server 721 for data communication with the playback apparatus 710, a data server 722 for transmitting moving pictures, and a database 723 for storing moving pictures. The web server 721 connects with a client connected to the Internet, the data server 722 processes various data, and the database 723 manages various data required for service connection. The Web server 721 is responsible for terminal connection, and the data server 722 is responsible for data processing. The web server 721 includes a script engine for processing requests of web browsers. The Web server 721 and the terminal perform HTTP communication, and the Web server 721 and the data server 722 perform TCP / IP communication.

In another embodiment, the playback apparatus 710 waits if it fails to establish a communication connection with the server 720. [ At this time, the playback apparatus 710 continuously plays back the moving image. The rotatable display device displays moving images. The playback apparatus 710 tries to access the server 720 at a designated time and plays back the downloaded video. When the video playback is completed, the playback device 710 repeatedly plays the downloaded video. If the connection is successful, the playback apparatus 710 downloads and plays the movie according to the movie play list and the scenario.

FIG. 8 is a flowchart illustrating an operation method of a rotatable display device according to an embodiment of the present invention.

A method of operating the rotating display device will be described.

The rotary display apparatus includes a program memory for storing a program, a data memory for storing data, and a processor for executing the program.

The program memory includes a step 810 of correcting the image data, a step 820 of reading the image data corresponding to the column, a process of converting the image data corresponding to the column into the serial data, And a step 830 of transmitting the serial data to the LED driver in synchronization with the frame rate of the image data.

A rotating display device executes a program stored in a program memory by a processor, and the operation will be described as follows.

The procedures executed in the rotating display device will be described in time series.

The rotary display device performs an image data correction step 810, a block interleaving step 820, and an image data serial output step 830 using an inverse gamma correction and an error diffusion method. As a first step, an image data correction step 810 using an inverse gamma correction and an error diffusion method may include an inverse gamma correction for converting the image data received from the moving image reproducing apparatus into a linear luminance characteristic, The image data using the error diffusion method is corrected to reduce the luminance reduction phenomenon. The rotating type display device checks the video signal section in the input signal and performs inverse gamma correction and error diffusion correction processing on the data of the section determined as the video signal section in real time. The rotating type display device simultaneously performs inverse gamma correction and error diffusion correction at intervals of one clock.

Secondly, the block interleaving step 320 is a step of reading out image data corresponding to a vertical column after storing image data of a frame inputted in a horizontal row in accordance with the input order for displaying Bar Type LEDs. When the image data having undergone the inverse gamma correction and the error diffusion correction is inputted, the rotation type display device carries out the operation of storing the image data in the internal DPRAM. The rotating type display device sequentially stores the data in the DPRAM in accordance with the output order in order to sequentially read the data from the memory when outputting data to the LED bar. The block interleaving step proceeds simultaneously with error diffusion correction and one clock interval.

Third, in the image data serial output step 830, parallel image data corresponding to the rotational position is converted into serial data and transmitted to the LED driver to transmit image data to be displayed on the LED bar rotating at a high speed. When all the data in the shift register are shifted, the rotary display device reads data from the DPRAM, stores the data in the shift register, and transmits the serial data to the LED driver while performing the shift operation.

1) Image data correction using inverse gamma correction and error diffusion (810)

The gamma correction was used initially to make the linear input of the camera nonlinear to compensate for the nonlinear characteristics because the CRT display had nonlinear characteristics. However, recent display devices are still used even though they have different linear characteristics from cathode ray. This is in order to show the best image quality at a given bit depth in response to the nonlinearity of human vision due to gamma coding, although it has become a social standard since the CRT period. In order to store image data in a high image quality using linear encoding, 11 bits or more are required for each component (R, G, B or Y, Cb, Cr), and when image data is stored using fewer bits Since posterization occurs, the image data is stored in 8 bits using a non-linear encoding method (gamma). Since the video signal received from the reproducing apparatus has non-linear brightness, the stored video data must be subjected to inverse gamma correction. When the inverse gamma correction is performed, the number of displayable luminance in the low gradation region is reduced, and a pseudo contour is generated. The rotary type display device corrects the problem by using error diffusion to reduce such a phenomenon of low gradation luminance decrease.

9 is a flowchart of an inverse gamma correction and error diffusion step according to an embodiment of the present invention.

① Problems of gradation expression in LED

As shown in FIG. 10, the conventional CRT exhibits a non-linear characteristic of the luminance displayed on the input signal. On the other hand, LEDs have mostly linear luminance characteristics within the operating range for the input signal. Human vision is characterized by being more sensitive to differences in dark areas than in bright areas. The nonlinear luminance characteristics of the CRT with respect to the digital input are suitable for reflecting human visual characteristics. Most video images are made to fit these CRT characteristics. Therefore, the luminance characteristic of the LED needs to be nonlinearly corrected as in the luminance characteristic of the CRT. This luminance correction process is called inverse gamma correction.

When the inverse gamma correction is performed, an error occurs between the luminance to be displayed and the displayed luminance because a value other than the displayable grayscale is requested from the LED. Due to such a phenomenon, a gradation representation problem that can not express the gradation smoothly in the dark region occurs.

Figure 11 shows the problem of gradation representation caused by inverse gamma correction. The abscissa represents the input gradation and represents only the dark portions 0 to 50 in the range of 0 to 255. It can be seen from the display luminance that although the input values are different, the display luminance is the same and the staircase phenomenon appears. The decrease in the number of gradations in such a low gradation region can not express the detail of the dark image and causes a false contour. In order to correct the error value between the ideal output value generated in the inverse gamma correction and the actual output value after the inverse gamma correction, a method of expressing the input value as an average value of a certain region is applied.

② Error diffusion for gradation representation

The rotational display device applies the error diffusion method shown in FIG. 12 for inverse gamma correction. The error diffusion method is originally used in a printer and is used to display 256 gradations using only two gradations of 0 and 255. [ The rotary display device propagates the error between the input gray level value and the output gray level value to the surrounding pixels to equalize the average gray level value of the entire image. Floyd and Steinberg have presented an error diffusion method that distributes errors such that such binarization errors are considered in the pixels to be binarized next. Unlike the dithering method, the error diffusion method is an area processing process in which binarization is determined not only by the binary pixels but also by the surrounding pixels. In the error diffusion method, the amount and magnitude of error to propagate to non-binarized surrounding pixels are determined by a weight defined as an error diffusion coefficient.

- (1.1)

- (1.2)

- (1.3)

- (1.4)

- (1.5)

- (1.6)

Equations (1.3) to (1.5) show the binarization process of the error diffusion method proposed by Floyd and Steinberg. Among the equations, (m, n) means the position of the pixel to be processed. x (m, n) represents an input tone value, and G (m, n) is a value corrected by an inverse gamma correction LUT to represent a prime number tone value satisfying a target gamma curve. In general, 0 represents a black dot and 255 represents a white dot. w (k, l) is an error diffusion coefficient that propagates the binarization error e (m, n) to the surrounding pixels belonging to the R region where the error diffusion coefficient is defined at a certain rate. T is a binary threshold used as a reference for determining the black point and the white point. In the Floyed-Steinberg method, 128 fixed values representing the halftone are used. Equation (1.6) shows the proposed error diffusion coefficient by Floyd and Steinberg.

The rotary type display device can reproduce a smooth image on the LED by compensating an error between a displayed gray level value and a target gray level value by an error diffusion method.

2) block interleaving 820

The block interleaving 820 refers to arranging digital data strings in a predetermined block unit, then exchanging columns and rows. The rotary type display device stores image data of horizontally input frames in accordance with the input order for displaying vertical type Bar Type LEDs, reads image data corresponding to the vertical columns, and performs image data block interleaving .

13 is a flowchart of the block interleaving step according to an embodiment of the present invention.

In a general monitor, video data is sequentially displayed in a horizontal line unit from left to right as shown in FIG. 14A. This is the same as the input signal, so the input can be output as it is.

Since the rotary display device manufactured by the present invention displays a video image by rotating the LED bar in the vertical direction, the video signal to be displayed on the LED should be displayed sequentially from top to bottom with respect to the vertical line. Accordingly, in order to sequentially store the input image frame by frame and to display the stored frame data on the LCD, it is necessary to collect and output only the vertical lines of the frame as shown in FIG. 14B. The rotatable display device manufactured in the present invention was designed to have a mechanical target of 900 RPM. The steps of calculating the displayable time and the display frame range while rotating the LED bar at 900 RPM are as follows.

<Step 1> As shown in FIG. 15A, the number of rotations of a 30 Hz frame image with one LED bar:

30 frames × 60 seconds = 1800 rotations / minute

<Step 2> As shown in FIG. 15B, the number of revolutions of a 30 Hz frame image with two LED bars:

30 frames × 60 seconds × 2Bar = 900 rotations / minute

In order to obtain a 30Hz frame video effect with two LED bars, it is necessary to rotate at 900 RPM, and the rotation rate per second is required to be 15 (revolutions per second).

<Step 3> Generally, the time taken per frame at 60 frames per second:

1 second / 60 frames = 16.666 ms / frame

&Lt; Step 4 > As shown in Fig. 16, the rotating body rotating at 15 revolutions per second has a rotation number of 16.666 ms:

15 revolutions / 60 seconds = 0.25 revolutions / frame

As shown in FIG. 17, when the number of LED bars is two, only one half of the frame information displayed by the LED is displayed while the one frame image is input to the FPGA (16.666ms) even if the LED is rotated at 900 RPM. Therefore, in order for the LED bar to display a full-frame image, two frames of time are required. This means that one frame out of two frames of the input image disappears. Therefore, it is necessary to store the data for the first one frame and output the stored data for the second frame as shown in FIG.

3) Video data serial output (830)

The image data serial output step 830 is a step of converting parallel image data corresponding to the rotation position into a serial and transmitting the serial image data to the LED driver so as to transmit image data to be displayed by the LED bar rotating at a high speed. The reason for the serial transmission is that the LED driver receives the input using the shift register and sequentially fills the adjacent channel or the next LED driver through the most significant bit of the shift register. Using a serial shift register reduces the signal attenuation through serial port repeaters and increases noise immunity even when the transmission length is long.

FIG. 19 is a flowchart of a step of outputting a video data serial according to an embodiment of the present invention.

In order to transfer data to the LED driver, the FPGA board generates signals. It implements the function of transmitting data based on the data sheet of the LED driver. One LED bar consists of 128 LED arrays, and the LED driver can control 16 LEDs. Therefore, eight LED drivers are required to control 128 LEDs. As mentioned above, the number of horizontal lines to be displayed for 16.666ms is 160 pieces. The step of calculating the video data transmission time of one pixel of the LED bar is as follows.

<Step 1> The time for one horizontal line is:

16.666ms / 160 pixels = 104.667us / pixel

104.667us, 1 line information corresponding to the vertical line should be transmitted to the Driver IC. Since the clock for transmitting data to the driver IC is 25 MHz, one clock is 40 ns.

<Step 2> To transfer data corresponding to one Driver IC:

16 bits x 16 channels x 40ns = 10.240us

<Step 3> To transfer data to 8 driver ICs:

10.240us x 8 IC = 81.920us

Since the time 104.667 us to be expressed by the rotation is larger than 81.920 us to transmit the data corresponding to the next line, there is no problem in the continuous data output of the image.

The rotary display device outputs line data through image data correction, block interleaving, and serial data output. The line image output to the light emitting portion appears as a moving image of a circular shape due to the afterimage effect.

20 is an exemplary view showing a moving image outputted by the rotation type display device

The rotatable display device outputs a circular transparent moving image. Drinking water can be seen inside the rotating display device through the transparent moving image. 20A is a moving image of a dark tone, FIG. 20B is a moving image of a middle tone, and FIG. 20C is a moving image of a bright tone. The rotating type display device can output moving images of various gradations by controlling the luminance to be different.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the present invention as defined by the following claims It can be understood that

600: rotative display device 610: playback device
620: FPGA board 630:
640: motor

Claims

A base block 111 which is a non-circulating member, two base blocks 112 fixedly coupled to the base plate 111, a support block 113 which interconnects the two base blocks 112, A main body 110 including a cover housing 114 surrounding the base block 112,
A rotation block 122 formed in a cylindrical shape and rotatably installed in the support block 113, a rotation plate 121 formed in a disk shape and connected to the rotation block 122, a support plate 113 connected to the support block 113, A rotating body 120 including a bearing for smoothly rotating the rotating block 122 and having a rotating center of rotation between the rotating block 122 and the rotating plate 121,
And is installed to extend upward at an upper edge of the rotary plate 121 of the rotary body 120 at a predetermined distance in the outward direction from the rotation center of the rotary body 120 A plurality of rotation frames 130 spaced apart from each other by 90 degrees in the circumferential direction of the rotation plate 121,
A support frame 131 formed in a circular rim shape to connect upper ends of the plurality of rotation frames 130 to prevent a plurality of rotation frames 130 from being bent,
A light emitting unit 140 installed in at least one of the plurality of rotation frames and emitting light according to an input signal,
An inner housing 150 of translucent material located between the plurality of rotation frames 130 and spaced from the rotation plate 121 and surrounding the rotation frame 130 and supported by the main body 110, A flange 190 connecting the upper end of the outer housing 160 and the upper end of the inner housing 150 so that the outer housing 160 supports the inner housing 150, ,
A reproducing unit for reproducing a moving image,
An FPGA board for reading the vertical line data of the moving image and outputting the vertical line data in synchronization with the rotational speed of the LED and the frame rate of the moving image,
A light emitting unit for driving the LED with the vertical line data,
And a motor for rotating the light emitting unit at the rotation speed,
The plurality of rotation frames 130 are disposed at different distances from the rotation center so that a space is formed by the rotation frame 130 during rotation,
An external display and an internal display are constituted by rotating frames disposed at different distances from the center of rotation and driven by an external electric signboard and an internal electric signboard,
Further comprising a black panel (180) provided between the light emitting part (140) and the rotation frame (130) to improve the contrast ratio,
The reproducing unit performs inverse gamma correction for converting a linear brightness characteristic and corrects image data using an error diffusion method to reduce a phenomenon of low gradation luminance reduction caused by inverse gamma correction,
Wherein the FPGA board is configured to perform inverse gamma correction for converting a linear luminance characteristic and to correct image data using an error diffusion method to reduce a phenomenon of low gradation luminance reduction caused by inverse gamma correction Typical display device.

The method of claim 1,
And a server for data communication with the reproducing unit to provide a moving image.

The method of claim 1,
Further comprising a display for outputting an advertisement image inside the rotatable display device.

A method of operating a rotatable display device using the rotatable display device of claim 1,
Reproducing the video data,
Reading image data corresponding to a column in the reproduced image data,
And converting the image data corresponding to the vertical column into serial data and synchronizing the rotation speed of the LED with the frame speed of the image data to transmit the serial data to the LED driver.

5. The method of claim 4,
The method of claim 1,
Performing inverse gamma correction to convert linear luminance characteristics,
And correcting the image data using an error diffusion method to reduce a phenomenon of low gradation luminance reduction caused by the inverse gamma correction.

5. The method of claim 4,
The step of reading comprises:
Storing image data of a frame input as a row in accordance with an input order,
And reading the image data corresponding to the vertical column from the stored image data.

5. The method of claim 4,
Wherein the transmitting comprises:
Converting the image data corresponding to the rotation position into the serial data,
And transmitting the serial data to the LED driver while performing a shift operation.