Patent Publication Number: US-2007109255-A1

Title: Method and Apparatus for Display

Description:
BACKGROUND OF THE INVENTION—FIELD OF INVENTION  
      This invention relates to an electronic display method and device, specifically using a mechanical scanning method to achieve a display resolution greater than the number of light emitting elements involved.  
     BACKGROUND OF THE INVENTION—PRIOR ART  
      Lighting elements, such as Light Emitting Diode (LED), have been arranged in dot matrixes for use of displaying text and graphic information. One of the biggest advantages of using LEDs compared with other display methods, such as plasma, liquid crystal and conventional Cathode Ray Tube (CRT,) is that LED display has high brightness, and dot matrix can be constructed to a large display area most suitable for indoor and outdoor advertisement. The dot-matrix construction of a display, however, inherently requires large amount of light elements when a high resolution and/or large display area is required. Hence the cost such a construction go up with higher resolution and/or larger area. High resolution and large display area are desirable display features for advertisement or information dissimulation. For example, a VGA resolution of such a display has 640×480 pixels. Over 900,000—640 times 480 times 3, LEDs are needed for such a display if each pixel consists of one of each of red, green and blue LEDs.  
      Improvements had been made to reduce the number of lighting elements needed, such as described by Wang in U.S. Pat. No. 5,818,401. Wang describes a display by mounting lighting elements on a rotating cylindrical body so that each vertical line of LEDs is responsible for displaying multiple lines of pixels so that fewer number of LEDs are used than that the resolution commands. However, such an implementation has a number of limitations. For example, a display based on U.S. Pat. No. 5,818,401 has a cylindrical and curved display surface that is less desirable than a flat displaying surface. Such a display device also occupies large real estate to install because the footprint needed is about 3.14 (Pi) times the square of the radius of the rotating cylinder.  
      The present invention involves a method of display that overcomes the disadvantages described above. Such a display apparatus employs mechanical and electronic methods to achieve higher resolution, lower cost, and large area of planar display surface, compared with the above and the conventional methods. 
    
    
     BRIEF DESCRIPTIONS OF THE DRAWINGS  
       FIG. 1  is a schematic view of the first embodiment of display apparatus according to the present invention.  
       FIG. 2  is a schematic view of the display stripe according to the present invention.  
       FIG. 3  is a schematic view of an embodiment of making electrical contacts between the power supply and the display stripes.  
       FIG. 3   b  is a schematic view of an alternative embodiment of making electrical contacts between the power supply and the display stripes, in accordance with the present invention.  
       FIG. 4  is a block-diagram view of the display controller system in accordance with the present invention.  
       FIG. 5  is a block-diagram view of the controller circuitries on the display stripes in accordance with present invention.  
       FIG. 6  illustrates the method of using mechanical scanning to form a display in a time-space relationship in accordance to the present invention. 
    
    
     SUMMARY OF PRESENT INVENTION  
      The present invention involves a method and apparatus to render graphic or text information on an electronic display. This method comprises of moving a conveyor base wrapped around two or more rotating shafts. The shafts are stationary mounted and are driven by a motor assembly to rotate at a desired speed, thereby the conveyor base also travels around the rotating shafts. A plurality of display stripes comprising of light emitting elements are harnessed on the conveyor base. The method further comprises of supplying constant power to the display stripes and a wireless means to communicate information between the display stripes and a stationary mounted display controller system. As the display stripes travel with the conveyor base, information is displayed accordingly in a controlled manor to render an image with resolution higher than the number of light emitting elements involved.  
      The preferred embodiment of the apparatus, as in the present invention, using this method is described in detailed and also as an illustration of the method in the present invention.  
     DETAILED DESCRIPTION OF THE METHOD AND THE PREFERRED EMBODIMENTS  
      In accordance with  FIG. 1 , the display apparatus comprises of a conveyor system ( 100 ), a plurality of display stripes ( 200 ) being harnessed on the conveyor base ( 110 ), a controlled motor drive assembly ( 300 ), a power supply ( 400 ) for the display stripes, and a display controller system ( 500 ).  
      The conveyor system ( 100 ) further comprises of a flexible conveyor base ( 110 ) that wraps around two or more rotating shafts ( 120 ). Although  FIG. 1  shows the use of two shafts, two or more shafts can be used. The conveyor base is made of flexible materials, in the form of a one contiguous piece of object, a bell-type object, or a “net” type of construction so as to provide a contiguous movement around the shafts. The rotating shafts are further stationary mounted with bearings ( 130 ) that are commonly used in mechanical devices. When the shafts being driven by a motor assembly ( 300 ), the conveyor base ( 110 ) travels around the shafts as used in commercially available conveyor systems. The rotation is controlled by a motor controller unit ( 310 ) to a desired speed. Such a motor controller design is also widely available commercially and the design can be done with an ordinary skilled electronic controller engineer.  
      A plurality of display stripess ( 200 ) are equal-spatially harnessed on the conveyor based ( 110 ) via mounting points ( 210 ). The number of mounting point ( 210 ) on each display stripes ( 200 ) and the physical method of mounting are not restricted, so long as they provide means of secured and durable attachment to the conveyor base ( 110 ). As shown in  FIG. 1 , the longitudinal side of the display stripes ( 210 ) is harnessed on the conveyor base  110  parallel to the shafts ( 120 ). This is the desirable orientation though it is not required as long as the stripes are not perpendicular to the shafts.  FIG. 2  is a more detailed depiction of the display stripes ( 200 ). The base material of the stripes can be a printed circuit board, though other materials can be used. A plurality of light emitting elements ( 220 ), such as LEDs, and herein being referred to as LEDs, are mounted along the longitudinal orientation of  200 . In such an arrangement, each display stripe ( 200 ) can be viewed as a 1×“n” resolution of display, where “n” is the number of LEDs on the stripe referred to as horizontal resolution and “1” refers to one line resolution on vertical direction. Although it is possible to construct a display stripe of “k” by “n” matrix of display stripes and still using the same principle of the present invention, “k” is set to one in the preferred embodiment. As shown in  FIG. 5 , on the display stripe ( 200 ), there are additional electronic circuitries ( 230 ) that comprise of solid-state memories and controllers ( 231  and  232 ) to provide means to control the desired on and off of the LEDs, as well as a communication circuitry ( 233 ) that communicate wirelessly with the display controller system ( 500 ). Control circuitries, such as using a micro-controller with programmable algorithms are commonly used in today&#39;s display electronics. Wireless methods commonly used include but not limited to RF and infrared technologies. The display apparatus also comprises of a transducer pair—one stationary actuator  240  for the apparatus, and one sensor  250  on each display stripe. When a display stripe travels with the conveyor base  110  and passes at the location of  250 , an electronic signal is triggered. This information is fed back to abovementioned controller circuitry ( 230 ) for use in controlling the display. Although other coupler devices can be used, a commonly used transducer pair is a photo coupler with  240  being an LED and  250  being a photo sensor.  
      In accordance with  FIG. 1 , the display apparatus further includes a power supply,  400 , having an anode and a cathode used to supply continuous electricity to the display stripes while the stripes ( 200 ) are traveling with the conveyor base ( 110 ). The commonly used method to maintain electronic contacts to a moving object is by using brush contact assembly, such as ones in brush electric motors. In such an assembly, a stationary brush made of graphite material makes a contact on a rotating copper contact so as to achieve low friction and low electric resistance. A preferred embodiment of the present invention is depicted in  FIG. 3 . In this embodiment, each display stripe has an anode and cathode electrodes ( 260  and  270 ) made of graphite material and extruding from the printed circuit board  200 . The stationary side of the contact  310  comprises of two electrically insolated rings made of conductive materials, such as copper.  410  has a shape that tracks the cross-section shape of the conveyor base ( 110 ). Each of the rings is electrically attached to the power supply anode and cathode, respectively.  260  and  270  make continuous electrical contacts with  300  while the display stripe ( 200 ) travels with the conveyor base ( 110 ) around the shafts ( 120 ), thereby constant power is supplied to all display stripes on the conveyor base ( 110 ).  FIG. 3   b  depicts an alternative embodiment of making electrical contacts between the power supply ( 400 ) and the display stripes ( 200 ). In this embodiment, a rotator with two electrically insolated contact rings R 1  and R 2  are mounted concentrically on a shaft  120 . A stator also has two electrical contacts, S 1  and S 2  connected to the power supply  400  and making contacts with R 1  and R 2 , respectively, while R 1  and R 2  rotates with the shaft  120 . The conveyor base ( 110 ) is embedded with two stripes (E 1  and E 2 ) made of flexible electrical conducting materials around  110  and overlay on R 1  and R 2 , respectively. Each display stripe ( 200 ) has two contact points (C 1  and C 2 ) making contact with E 1  and E 2  respectively. Thereby, when the display stripes ( 200 ) travel around the shafts ( 120 ), constant electrical contacts are made between the stripes and the power supply via C 1 &amp;C 2 , E 1 &amp;E 2 , R 1 &amp;R 2 , and S 1 &amp;S 2 , respectively.  
      In accordance with  FIG. 1 , the present invention further comprises of a display controller system  500 . This system includes a number of functional blocks, as depicted in  FIG. 4 . It includes a video processing unit  510  that processes information from varies sources, such as from video inputs, computer generated graphic inputs, etc. The controller system also includes a wireless communication unit  530  that is capable of communicating the processed data from  510  wirelessly to the circuitry in  233  on display stripes ( 200 ). Controller system  500  further includes a motor sensing and control unit  520  that provide means to coordinate between the displayed information and the motor speed driven by the motor controller  310 . Such a control process is described with further details below.  
      The present invention prescribes a method of electronic display using a coordination of mechanical scanning together with precise controlling of LEDs so as to achieve using fewer LEDs than otherwise the resolution commands.  FIG. 6  illustrates the time-location relations of the mechanism in this method. A display surface ( 111 ) is an area on the conveyor base ( 110 ) confined between two adjacent shafts ( 120 ) consisting of a number of display stripes ( 200 ). The steady image rendered on this display surface ( 111 ) is made of a matrix of “m” by “n” pixels ( 112 ), where “m” is the vertical resolution and “n” is the horizontal resolution for the simplicity of description, and both being integers as number of pixels. The pixel pitch size “p” is the measurement between each adjacent pixel location. Although it is not a requirement, “p” is the same in horizontal and vertical directions for simplicity of description. The display stripes ( 200 ) overlay on selected pixel locations at a given moment and the distance between any two stripes is “a”, where “a” is made to be two or more times of “p”. The LEDs on each display stripe can be viewed as a “1” by “n” matrix and also has a horizontal pixel pitch size of “p”. When the display stripes ( 200 ) travel with the conveyor base and going through each image horizontal pixel lines, they display the corresponding pixel information. The time-location description of this process is demonstrated in the  FIG. 6  with three display stripes annotated as DS 1 , DS 2 , and DS 3  as the following and assuming “a” equals four times of “p”:  
      At time t 0 , display stripes (DS 1 , DS 2 , DS 3 ) are at location PL 1 , PL 5 , PL 9 , respectively and display the corresponding information of the first frame for those pixel lines. PL 1 ˜PL 12  annotate the consecutive horizontal lines of pixels;  
      At time t 1 , DS 1 , DS 2 , and DS 3  travels to new locations at PL 2 , PL 6  and PL 10 , respectively and display the corresponding information of the first frame for those lines;  
      At time t 2 , DS 1 , DS 2 , and DS 3  travels to new locations at PL 3 , PL 7  and PL 11 , respectively and display the corresponding information of the first frame for those lines;  
      At time t 3 , DS 1 , DS 2 , and DS 3  travels to new locations at PL 4 , PL 8  and PL 12 , respectively and display the corresponding information of the first frame for those lines;  
      At time t 4 , DS 1  travels to PL 5 , DS 2  travels to PL 9 , and DS 3  travels to PL 13  (not shown in  FIG. 6 ), respectively and display the corresponding information of the second frame for those lines, and so on.  
      Such a process continues so that all horizontal pixel lines are displayed by the display stripes with their corresponding information in a frame by frame fashion.  
      Due to persistence of vision, human eyes perceive the above process as fully steady images so long as the above process takes place at a sufficient frame rate, usually described by frames per second or frame rate. It is well known that when display is at 30 frames/s, human eyes will perceive a steady image. In the present invention, the conveyor base traveling speed “s” is to be controlled in order to achieve a desirable frame rate “f” based on the following relations:
 
 “s”=“f”×“p” ×( “a”+“p” ).
 
 In another word, the line speed, “s” required for the conveyor base to travel to achieve a desired frame rate “f” is “f” multiplied by the pixel pitch size “p” and multiplied by a “scanning factor” defined by the ratio of “a” and the pixel pitch size, “p”. 
 
      In accordance with  FIG. 1 , a display surface is an area confined as the conveyor base ( 110 ) with display stripes ( 200 ) between two adjacent shafts. In an apparatus with two shafts, there could be a maximum of two such display faces. In case of three shafts, the maximum number of such display face is three, and so on. The apparatus in the present invention can further include many techniques today in used for conventional displays, such as an enclosure with transparent openings to confine the display viewing area while providing physical protections, shields to deflect sunlight to improve contrast ratios, etc. to further improve the viewing quality. These kinds of techniques do not interfere with the principle operation of the current invention and can be adopted as needed.  
      Although the invention has been explained in relation to its preferred embodiment, it is to be understood that many other possible modifications and variations can be made without departing from the spirit and scope of the invention as hereinafter claimed.