Patent Publication Number: US-2023154366-A1

Title: Pov display device and control method therefor

Description:
TECHNICAL FIELD 
     The present disclosure is applicable to a display device-related technical field, and relates, for example, to a POV (Persistence of Display) display device using light emitting diodes (LEDs), which are semiconductor light emitting elements. 
     BACKGROUND ART 
     In a field of a display technology, display devices having excellent characteristics such as thinness, flexibility, and the like have been developed. On the other hand, currently commercialized major displays are represented by a LCD (liquid crystal display) and an OLED (organic light emitting diode). 
     Recently, there is a POV (Persistence of Display) display device that may reproduce various characters and graphics as well as moving images using an afterimage effect of a human by rotating a light emitting module in which light emitting elements are one-dimensionally arranged, and at the same time, driving the light emitting module at a high speed based on an angle. 
     In general, when continuously observing 24 or more still images for each second, a viewer recognizes the still images as the moving image. A conventional image display device, such as a CRT, the LCD, or a PDP, displays still images of 30 to 60 frames for each second, so that the viewer may recognize the still images as the moving image. In this regard, when continuously observing more still images for each second, the viewer may feel smoother images. As the number of still images displayed for each second decreases, it becomes difficult to smoothly display the images. 
     In this regard, in the POV display, as a difference between image data input to a memory and image data output is generated, a phenomenon in which an image is torn, that is, a tearing phenomenon occurs. 
     Therefore, a method for preventing such tearing phenomenon of the POV display device is required. 
     DISCLOSURE 
     Technical Problem 
     The present disclosure is to provide a POV (Persistence of Vision) display device that suppresses an occurrence of a tearing phenomenon of a screen. 
     Technical Solutions 
     As a first aspect for achieving the above object, the present disclosure provides a persistence of vision (POV) display device using light emitting elements including a fixed module including a motor, a rotatable module positioned on the fixed module and rotated by the motor, at least one panel coupled to the rotatable module, a plurality of light sources arranged on the panel and constituting a plurality of pixels, a light source module including a light emitting element array having the plurality of light sources arranged in a longitudinal direction, a memory for storing video data received from an external source device, and a controller that controls an input order of the video data and an output order of the video data. 
     In addition, the controller may divide one video frame based on the number of panels and then input the divided video frames into the memory. 
     In addition, the controller may store the divided video frames in the memory in parallel with each other or in data packet units. 
     In addition, the controller may convert an image only at a time point of conversion of the video frame. 
     In addition, the panel may include a plurality of panels and the memory may include a plurality of memories. 
     In addition, the controller may divide one video frame based on the number of panels and then input the divided video frames into the plurality of memories. 
     In addition, the controller may store the divided video frames in the memories in parallel with each other or in data packet units. 
     In addition, the controller may convert an image only at a time point of conversion of the video frame. 
     As a first aspect for achieving the above object, the present disclosure provides a method for controlling a persistence of vision (POV) display device including receiving video data from an external source device, dividing one video frame contained in the received video data based on the number of panels included in the POV display device, inputting the divided video frames into a memory, and outputting the divided video frames from the memory, wherein a controller controls an order of inputting the video frames from the external source device to the memory and an order of outputting the video frames from the memory to the panel. 
     In addition, the inputting of the divided video frames into the memory may include storing the divided video frames in parallel with each other or in data packet units. 
     ADVANTAGEOUS EFFECTS 
     According to one embodiment of the present disclosure, the problem as described above may be solved. 
     That is, the tearing phenomenon of the image in the POV display device may be prevented. 
     Furthermore, in the present disclosure, there are additional technical effects not mentioned here, and those skilled in the art are able to understand such effects through the entirety of the specification and the drawings. 
    
    
     
       DESCRIPTION OF DRAWINGS 
         FIG.  1    is a perspective view showing a POV (Persistence Of Visual) display device according to an embodiment of the present disclosure. 
         FIG.  2    is a perspective view showing a front surface of a light source module according to an embodiment of the present disclosure. 
         FIG.  3    is a perspective view showing a rear surface of a light source module according to an embodiment of the present disclosure. 
         FIG.  4    is a partially enlarged view of  FIG.  2   . 
         FIG.  5    is a cross-sectional view of a light source module according to an embodiment of the present disclosure. 
         FIG.  6    is a block diagram of a POV display device according to an embodiment of the present disclosure. 
         FIG.  7    is a block diagram of a POV display device according to an embodiment of the present disclosure. 
         FIG.  8    is a flowchart of one embodiment of the present disclosure. 
         FIG.  9    is a diagram showing a video frame output order of panels. 
         FIG.  10    is a graph showing input video data and output video data of the prior art. 
         FIG.  11    is a graph showing input image data and output image data according to an embodiment of the present disclosure. 
     
    
    
     BEST MODE 
     Reference will now be made in detail to embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts, and redundant description thereof will be omitted. As used herein, the suffixes “module” and “unit” are added or used interchangeably to facilitate preparation of this specification and are not intended to suggest distinct meanings or functions. In describing embodiments disclosed in this specification, relevant well-known technologies may not be described in detail in order not to obscure the subject matter of the embodiments disclosed in this specification. In addition, it should be noted that the accompanying drawings are only for easy understanding of the embodiments disclosed in the present specification, and should not be construed as limiting the technical spirit disclosed in the present specification. 
     Furthermore, although the drawings are separately described for simplicity, embodiments implemented by combining at least two or more drawings are also within the scope of the present disclosure. 
     In addition, when an element such as a layer, region or module is described as being “on” another element, it is to be understood that the element may be directly on the other element or there may be an intermediate element between them. 
     The display device described herein is a concept including all display devices that display information with a unit pixel or a set of unit pixels. Therefore, the display device may be applied not only to finished products but also to parts. For example, a panel corresponding to a part of a digital TV also independently corresponds to the display device in the present specification. The finished products include a mobile phone, a smartphone, a laptop, a digital broadcasting terminal, a personal digital assistant (PDA), a portable multimedia player (PMP), a navigation system, a slate PC, a tablet, an Ultrabook, a digital TV, a desktop computer, and the like. 
     However, it will be readily apparent to those skilled in the art that the configuration according to the embodiments described herein is applicable even to a new product that will be developed later as a display device. 
     In addition, the semiconductor light emitting element mentioned in this specification is a concept including an LED, a micro LED, and the like, and may be used interchangeably therewith. 
       FIG.  1    is a perspective view showing a POV (Persistence Of Visual) display device according to an embodiment of the present disclosure. 
       FIG.  1    shows a POV display device in which each light emitting element array (not shown, see  FIG.  2   ) is disposed on each of fan type-panels  310 ,  320 ,  330 , and  340  in a longitudinal direction of each panel. Although  FIG.  1    shows the fan type-POV display device, the present disclosure is also applicable to a display device that requires input/output of data, such as a cylinder type POV display device. 
     Such POV display device may include a fixed module  100  including a motor (not shown, see  FIG.  7   ), a rotatable module  200  positioned on this fixed module  100  and rotated by the motor, and a light source module  300  that is coupled to the rotatable module  200 , includes the light emitting element arrays, and displays an afterimage by the rotation so as to implement a display. 
     In this regard, the light source module  300  may include the one or more bar-shaped panels  310 ,  320 ,  330 , and  340  radially disposed from a central point of rotation. However, this is an example, and the light source module  300  may include one or more panels. 
     The light source module  300  may include the light emitting element arrays arranged on the panels  310 ,  320 ,  330 , and  340  in the longitudinal direction, respectively. 
     Each of the panels constituting the light source module  300  may form a printed circuit board (PCB). That is, each of the panels may have a function of the printed circuit board. In each of such panels, each of the light emitting element arrays may implement individual unit pixels and may be disposed in the longitudinal direction of each of the panels  310 ,  320 ,  330 , and  340 . 
     The panels  310 ,  320 ,  330 , and  340  respectively equipped with such light emitting element arrays may implement the display while rotating using the afterimage. The implementation of the afterimage display will be described in detail below. 
     As such, the light source module  300  may be composed of the panels  310 ,  320 ,  330 , and  340  on which the light emitting element arrays are respectively arranged. 
     That is, multiple light emitting elements (not shown, see  FIG.  4   ) may be arranged in one direction on each of the panels  310 ,  320 ,  330 , and  340  to constitute pixels so as to constitute each of the light emitting element arrays. In this regard, a light emitting diode (LED) may be used as the light emitting element. 
     On each of the panels  310 ,  320 ,  330 , and  340 , each of the light emitting element arrays on which the light emitting elements are arranged to form individual pixels in one direction and are linearly installed may be disposed. 
     As mentioned above, the light source module  300  may be composed of the multiple panels  310 ,  320 ,  330 , and  340 , but may also be implemented with a single panel including the light emitting element arrays. However, when the light source module  300  is implemented with the multiple panels as in the example in  FIG.  1   , because the multiple panels may implement one frame image in a divided manner, the light source module  300  may rotate at a lower rotation speed than when implementing the image of the same frame. 
     In one example, the fixed module  100  may form frame structures. That is, the fixed module  100  may include multiple frames  101  that are designed to be divided from each other and coupled with each other. 
     Such frame structures may provide a space in which the motor may be installed, and may provide a space in which a power supply  120 , an RF module (not shown, see  FIG.  7   ), and the like are installed. 
     In addition, a weight (not shown) may be installed in the fixed module  100  in order to reduce an effect of the high-speed rotation of the rotatable module  200 . 
     Similarly, the rotatable module  200  may form frame structures. That is, the rotatable module  200  may include multiple frames  201  that are designed to be divided from each other and coupled with each other. 
     Such frame structures may provide a space in which a driving circuit for driving the light emitting element arrays to implement the display is installed. 
     In this regard, a driving shaft of the motor may be fixed with a shaft fixing module formed in a lower frame  201  of the rotatable module  200 . As such, the driving shaft of the motor and a center of rotation of the rotatable module  200  may be located on the same axis. 
     In addition, the light source module  300  may be fixedly installed on the frame  201 . 
     In one example, power may be transferred between the fixed module  100  and the rotatable module  200  in a wireless power transfer scheme. To this end, a transfer coil  130  for transmitting wireless power may be installed at a top of the fixed module  100 , and a receiving coil  220  located at a position facing the transfer coil  130  may be installed at a bottom of the rotatable module  200 . 
       FIG.  2    is a perspective view showing a front surface of a light source module according to an embodiment of the present disclosure, and  FIG.  3    is a perspective view showing a rear surface of a light source module according to an embodiment of the present disclosure. 
     Although  FIGS.  2  and  3    illustrate a first panel  310  of one embodiment of the present disclosure as an example, the same may be applied to other panels  320 ,  330 , and  340 . 
     Referring to  FIG.  2   , one panel  310  constituting the light source module  300  is shown. As mentioned above, such panel  310  may be a printed circuit board (PCB). Multiple light emitting elements (not shown, see  FIG.  4   ) may be arranged on the panel  310  and installed in one direction to form pixels so as to form a light emitting element array  311 . In this regard, the light emitting diode (LED) may be used as the light emitting element. 
     That is, a light emitting element array  311  in which light emitting elements  312  are arranged so as to form individual pixels in one direction and are linearly installed may be disposed on one panel  310 . 
       FIG.  3    shows a rear surface of the panel  310 . Driver modules  314  for driving the light emitting elements (not shown, see  FIG.  4   ) may be installed on the rear surface of the panel  310  constituting such light source module  300 . The driver module  314  may be, for example, a driver IC. 
     As such, the driver modules  314  are installed on the rear surface of the panel  310 , so that a light emitting surface of the panel may not be disturbed, an effect on lighting of light sources (the light emitting elements) caused by interference or the like may be minimized, and the panel  310  may be constructed with a minimal area. Such panel  310  with the small areas may improve transparency of the display. 
     In one example, the front surface of the panel  310  on which the light emitting element array  311  is installed may be treated with a dark color (for example, black) so as to improve a contrast ratio, a color, and the like of the display, thereby maximizing an effect of the light sources. 
       FIG.  4    is a partially enlarged view of  FIG.  2   , and  FIG.  5    is a cross-sectional view of the light source module  300  according to an embodiment of the present disclosure. 
     Referring to  FIG.  4   , it may be seen that the individual light emitting elements  312  are linearly installed in one direction (a length direction of the panel). In this regard, a protection portion  313  for protecting the light emitting elements  312  may be positioned outwardly of the light emitting elements  312 . 
     In such light emitting elements  312 , red, green, and blue light emitting elements  312  may constitute one pixel so as to realize natural colors, and such individual pixels may be installed on the panel  310  in one direction. 
     Referring to  FIG.  5   , the light emitting elements  312  may be protected by the protection portion  313 . In addition, as described above, the driver modules  314  may be installed on the rear surface of the panel  310  so as to drive the light emitting elements  312  in units of pixels or sub-pixels. In this regard, one driver module  314  may individually drive at least one pixel. 
       FIG.  6    is a block diagram of a POV display device according to an embodiment of the present disclosure. 
     A memory controller  214  may receive video data from an external source device  400  and input the received video data to a memory  217 . In addition, the memory controller  214  may output video data required by the light source module  300  and transmit the video data to the driver module  314 . 
     That is, the memory controller  214  may divide the video data and control an order in which the divided data are input to the memory  217  and an order in which the divided data are output from the memory  217  so as to allow an image to be converted only at a time point of frame conversion, thereby preventing a phenomenon in which an image is torn, that is, a tearing phenomenon during frame conversion. 
     In this regard, an image scanning rate and a frames per second (FPS) do not necessarily match each other. 
     The memory  217  may be either an internal or external memory. 
       FIG.  7    is a block diagram of a POV display device according to an embodiment of the present disclosure. 
     Hereinafter, a configuration for driving the POV display device will be briefly described with reference to  FIG.  7   . 
     First, a driving circuit  120  may be installed in the fixed module  100 . Such driving circuit  120  may include a power supply. The driving circuit  120  may include a wireless power transmitter  121 , a DC-DC converter  122 , and an LDO  123  for supplying individual voltages. 
     External power may be supplied to the driving circuit  120  and the motor  110 . 
     In addition, the fixed module  100  may have an RF module  126 , so that the display may be driven by a signal transmitted from the outside. 
     In one example, the fixed module  100  may have means for sensing the rotation of the rotatable module  200 . An infrared ray may be used as such means for sensing the rotation. Accordingly, an IR emitter  125  may be installed in the fixed module  100 , and an IR receiver  215  may be installed in the rotatable module  200  at a location corresponding to an infrared ray emitted from such IR emitter  125 . 
     In addition, the fixed module  100  may include a controller  124  for controlling the driving circuit  120 , the motor  110 , the IR emitter  125 , and the RF module  126 . 
     In one example, the rotatable module  200  may include a wireless power receiver  211  for receiving a signal from the wireless power transmitter  121 , a DC-DC converter  212 , and an LDO  213  for supplying individual voltages. 
     The rotatable module  200  may have an image processor  216  that processes the image to be realized via the light emitting element arrays using RGB data of the displayed image. A signal processed by the image processor  216  may be transmitted to the driver module  314  of the light source module  300  so as to realize the image. 
     In addition, in the rotatable module  200 , a controller  214  for controlling the wireless power receiver  211 , the DC-DC converter  212 , the LDO  213 , the IR receiver  215 , and the image processor  216  may be installed. 
     Such image processor  216  may generate a signal for controlling light emission of the light sources of the light source module  300  based on image data to be output. In this regard, data for the light emission of the light source module  300  may be internal or external data. 
     The data stored internally (in the rotatable module)  200  may be image data stored in advance in a storage device, such as a memory (e.g., a SD card), mounted together in the image processor  216 . The image processor  216  may generate the light emission control signal based on such internal data. 
     The image processor  216  may transmit, to the driver module, a signal for controlling image data of a specific frame to be displayed on each light emitting element array after delay. 
     In addition, the image processor  216  may receive the image data from the fixed module  100 . In this regard, the external data may be output via an optical data transmitting device with the same principle as a photo coupler, or a data transmitting device of an RF scheme such as Bluetooth or Wi-Fi. 
     In this regard, as mentioned above, the means for sensing the rotation of the rotatable module  200  may be disposed. That is, as means for recognizing a location (a speed) with respect to the rotation, such as an absolute location and a relative location with respect to the rotation, so as to output light source data suitable for each rotational position (speed) during the rotation of the rotatable module  200 , the IR emitter  125  and the IR receiver  215  may be arranged. In one example, the same function may be implemented via an encoder, a resolver, and a Hall sensor. 
     In one example, data required to drive the display may optically transmit a signal at a low cost using the principle of the photo coupler. That is, when the light emitting elements and light receiving elements are positioned in the fixed module  100  and the rotatable module  200 , the data may be received without interruption even when the rotatable module  200  rotates. In this regard, the IR emitter  125  and the IR receiver  215  described above may be used for such data transmission. 
     As described above, the power may be transferred between the fixed module  100  and the rotatable module  200  using the wireless power transfer (WPT). 
     The power may be supplied without a wire connection using a resonance shape of the wireless power transfer coil. 
     To this end, the wireless power transmitter  121  may convert the power into an RF signal of a specific frequency, and a magnetic field generated by a current flowing through the transfer coil  130  may generate an induced current in the receiving coil  220 . 
     In this regard, a natural frequency of the coil and a transmission frequency at which actual energy is transmitted may be different from each other (a magnetic induction scheme). 
     In one example, resonant frequencies of the transfer coil  130  and the receiving coil  220  may be the same with each other (a self-resonant scheme). 
     The wireless power receiver  211  may convert the RF signal input from the receiving coil  220  into a direct current so as to transmit required power to a load. 
       FIG.  8    is a flowchart of one embodiment of the present disclosure. 
     As shown in  FIG.  8   , the memory controller  214  receives the video data from the external source device  400  (s 801 ). 
     In addition, the memory controller  214  divides a frame of the received video data based on the number of panels of the POV display device (s 802 ), and inputs the divided video frames into the memory  217  (s 803 ). 
     The divided video frames are output (s 804 ). 
     In a following embodiment, it is shown that there are four panels, but the number of panels is not limited thereto. 
       FIG.  9    is a diagram showing a video frame output order of panels. 
     In (a) in  FIG.  9   , an Nth frame is shown, and in (b) in  FIG.  10   , an N+1th frame is shown. In other words, even when one video frame is input, when there are 4 panels, the frame is output after being divided based on the number of panels. 
       FIG.  10    is a graph showing input video data and output video data of the prior art. 
     As shown in  FIG.  9   , the video data is output in a manner of being divided based on the number of panels P 0 , P 1 , P 2 , and P 3 . Movement paths of the panels P 0 , P 1 , P 2 , and P 3  are indicated by solid lines. 
     Specifically, in the prior art, an entirety of one video frame was input (bold dotted lines) to the memory  217  without the division, and the video frame was sequentially output from the memory  217  to the panels P 0 , P 1 , P 2 , and P 3 . Therefore, the tearing phenomenon in which the image is torn occurred as one frame was converted at a time point that is not a time point at which the frame is converted as shown in {circle around (a)} or two frames were converted together as shown in {circle around (b)}. 
       FIG.  11    is a graph showing input image data and output image data according to an embodiment of the present disclosure. 
     As shown in  FIG.  9   , the video data are output based on the number of panels P 0 , P 1 , P 2 , and P 3 . The movement paths of the panels P 0 , P 1 , P 2 , and P 3  are indicated by solid lines. 
     Unlike the prior art, in the present disclosure, in order to synchronize the input and the output with each other, the memory controller  214  may divide one video frame input from an external source in an order of {circle around ( 1 )}, {circle around ( 2 )}, {circle around ( 3 )}, and {circle around ( 4 )}, which is an order of the panels to be output, and input (bold dotted lines) the divided video frames to the memory  217 . In addition, the memory controller  214  may output (thin dotted lines) the divided video data from the memory  217  based on the order of the input video data. 
     For this reason, the input data and the output data may be prevented from not being synchronized with each other, so that the tearing phenomenon may be prevented. 
     In addition, one frame image may be divided based on the number of panels, and the divided frame images may be stored in parallel with each other or in data packet units. 
     In this regard, the image scanning rate and the frames per second (FPS) do not necessarily match each other, but the image may be designed to be converted only at the time point at which the frame is converted. 
     As described above, in the present disclosure, the POV display device may divide the data and input the divided date to the memory so as to synchronize the input and the output with each other, thereby allowing the image to be converted only at the time point of the frame conversion. Therefore, the occurrence of the phenomenon in which the screen is torn, that is, the tearing phenomenon during the frame conversion may be solved. 
     The above description is merely illustrative of the technical idea of the present disclosure. Those of ordinary skill in the art to which the present disclosure pertains will be able to make various modifications and variations without departing from the essential characteristics of the present disclosure. 
     Therefore, embodiments disclosed in the present disclosure are not intended to limit the technical idea of the present disclosure, but to describe, and the scope of the technical idea of the present disclosure is not limited by such embodiments. 
     The scope of protection of the present disclosure should be interpreted by the claims below, and all technical ideas within the scope equivalent thereto should be construed as being included in the scope of the present disclosure.