Abstract:
A signal transmission system of electronic display devices includes a plurality of electronic display devices and a wireless signal transmission device. The wireless signal transmission device broadcasts a first packet data to the electronic display device. The first packet data comprises an access control address list, and the access control address list comprises the MAC address of a first group of electronic display device. When the wireless signal transmission device receives an acknowledgement (ACK) message from at least a first electronic display device of the first group of electronic display devices, the wireless signal transmission device changes the method of transmission from broadcast to unicast in order to transmit second packet data to the first electronic display device, wherein the second packet data comprises video packet data.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority of Taiwan Patent Application No. 101103331, filed on Feb. 2, 2012, the entirety of which is incorporated by reference herein. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The disclosure is related to a signal transmission system of an electronic display device. 
         [0004]    2. Description of the Related Art 
         [0005]    Electronic Shelf Label (ESL) Systems provide electronic shelf labels placed on shelves, replacing traditional paper price labels. Electronic shelf labeling makes it easy to modify the price of products, and doesn&#39;t waste a lot of human resources for modifying the paper price labels. 
       BRIEF SUMMARY OF THE INVENTION 
       [0006]    An embodiment of the invention provides a signal transmission system of an electronic display device which comprises a plurality of electronic display devices; and a wireless signal transmission device configured to transmit a first packet data to the plurality of electronic display devices by broadcast, wherein the first packet data comprises an access control address list and the access control address list records an media access control address of a first group of electronic display devices of the plurality of electronic display devices; and when the wireless signal transmission device receives an ACK message from at least one first electronic display device of the first group of electronic display devices, the wireless signal transmission device changes the method of transmission from broadcast to unicast for transmitting a second packet data to the first electronic display device, wherein the second packet data comprises a video packet data, and when the access control address of the first group of electronic display devices is in the access control address list, the ACK message is transmitted to the wireless signal transmission device. 
         [0007]    An embodiment of the invention provides a transmission method wherein the transmission method is appropriate for using in the environment of a signal transmission system of electronic display devices, comprising: a wireless signal transmission device transmitting a first packet data to the plurality of electronic display devices by broadcast, wherein the first packet data comprises an access control address list and the access control address list records an access control address of a first group of electronic display devices of the plurality of electronic display devices; and transmitting an ACK message to the wireless signal transmission device, when a MAC address of at least one first electronic display device is in the access control address list; and changing the method of transmission from broadcast to unicast for transmitting a second packet data to the first electronic display device, when the wireless signal transmission device receives the ACK message from the first electronic display device of the first group of the electronic display devices; wherein the second data comprises a video packet data. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    The invention will become more fully understood by referring to the following detailed description with reference to the accompanying drawings, wherein: 
           [0009]      FIG. 1  is schematic diagram illustrating the signal transmission system  100  of the electronic display device according to an embodiment of the invention; 
           [0010]      FIG. 2  is schematic diagram illustrating the signal transmission system of the electronic display device according to another embodiment of the invention; 
           [0011]      FIGS. 3A-3B  are a flowchart of the transmission method according to an embodiment of the invention; 
           [0012]      FIG. 4  is a flowchart of the transmission method according to an embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0013]    Embodiments, or examples, illustrated in the drawings are disclosed below using specific language. It will nevertheless be understood that the embodiments and examples are not intended to be limiting. Any alterations and modifications in the disclosed embodiments, and any further applications of the principles disclosed in this document are contemplated as would normally occur to one of ordinary skill in the pertinent art. 
         [0014]    The embodiments of present invention could be applied to the signal transmission system of the electronic shelf label. There are some present methods of modifying the image data on the electronic shelf label. One method is that routers transmit the image data needed to be updated to each of the electronic shelf label via broadcast. Another method is that routers transmit the image data needed to be updated to each of the electronic shelf label by a unicast method. 
         [0015]      FIG. 1  is a schematic diagram illustrating the signal transmission system  100  of an electronic display device according to an embodiment of the invention. The signal transmission system  100  comprises a plurality of electronic display devices  102 , a wireless signal transmission device  104 , a coordinator  106  and a server  108 . For example, the electronic display devices  102  comprises a wireless communication module  110 , power supply unit  111 , processing unit  112 , detection unit  113 , display unit  114 , and voice module  115 . 
         [0016]    The forms of display unit  114  comprise Electrophoretic Display, MEMS Display, Organic Light-Emitting Diode Display, and Liquid Crystal Display, wherein the MEMS Display comprises a mirasol display. Display unit  114  could be a display on the electronic shelf label or on the billboard. The Electrophoretic Display and the MEMS Display are activated only when the state of the display is changed. When the state of the display is not changed, power to the display would be closed, and the screen of the display still could maintain the display information, wherein the feature described above is called “bistable”, and the feature is so electricity-saving that it is very well suited to application in an electronic shelf label environment. 
         [0017]    The Power supply unit  111  comprises a battery wherein the battery could be a cylindrical battery (such as Zinc-MnO2 battery, Carbon-Zinc battery, Alkaline battery, Nickel-Metal Hydride battery or Nickel-Cadmium battery), a button battery (such as Mercury battery), a Lithium battery, a Solar Energy battery module or another power supply resource. Power supply unit  111  could be charged by a wireless transmission method, wherein the wireless transmission method comprises a radio frequency (RF) transmission method. 
         [0018]    The Wireless communication module  110  and the wireless signal transmission device  104  transmit data to the server  108  by a wireless communication method. The wireless communication module  110  can be RF communication module, Bluetooth communication module, 3 G communication module (such as CDMA module, WCDMA module or TD-SCDMA module), 4 G communication module (such as LTE module or WIMAX module), Wi-Fi communication module, Near Field Communication (NFC) module or other wireless communication module. The Wireless signal transmission device  104  can be a wireless router, wireless transmission base station or any other device which transmits and receives signals by wireless transmission such as a mobile phone, tablet, or notebook computer. 
         [0019]    The Processing unit  112  could be a central-processing unit (CPU) or a plurality of parallel processing units associated with the parallel processing environment, used to execute operation system, module and application program. 
         [0020]    The Detection unit  113  comprises an optical sensor, such as an infrared ray sensor. When a customer passes through the electronic display devices  102 , the detection unit  113  can sense the customer, and transmit a signal to the display unit  114  or the voice module  115 . If the signal is transmitted to the display unit  114 , the display unit  114  will alert the customer by some display state, e.g. reminding the customer that certain products are on sale or other activity information by a twinkling or animation method. If the signal is transmitted to the voice module  115 , the voice module  115  will remind the customer by generating a voice. The Detection unit  113  and the voice module  115  could close their functions by the server  108  via a wireless network and the wireless signal transmission device  104 . 
         [0021]    For example, the wireless signal transmission device  104  comprises wireless communication module  118 , processing unit  120  and storage unit  122 . The Wireless communication module  118  transmits data with the electronic display devices  102  and coordinator  106  by wireless network, wherein the wireless communication module  118  can be an RF communication module, Bluetooth communication module, 3 G communication module (such as CDMA module, WCDMA module or TD-SCDMA module), 4 G communication module (such as LTE module or WIMAX module), Wi-Fi communication module, Near Field Communication (NFC) module or other wirelss communication module. In one embodiment of the invention, the wireless signal transmission device  104  and the coordinator  106  transmit data by wireless network protocol Zigbee used in low rate and short distant transmission. For example, the processing unit  120  could be a central-processing unit (CPU) or a plurality of parallel processing units associated with the parallel processing environment, used to execute an operation system, module and application program. The Storage unit  122  can be ROM memory, flash memory, RAM memory, EPROM memory, EEPROM memory, registers, a hard disk and/or any other form of computer-readable storage medium known in the skill of art. 
         [0022]    In one embodiment of the invention, the server  108  has a storage unit (not present) configured to store the data (video data and/or audio data) input by user, wherein the video data and the audio data are the price of a product, a text description or product-selling description. For example, when a user wants to change the price, image or voice of the product displayed in the electronic display devices  102  which is on the shelf, the user can store the video data or the audio data of the product in the server  108  in advance, wherein the video data or the audio data comprise the price, the text description, e.g. on sale, picture or voice. Each single unit of video data or audio data corresponds to a product, and the electronic display device  102  of every product has a unique media access control (MAC) address. Therefore, each unit of video data or audio data has the MAC address corresponding to the electronic display device  102 . Then, the server  108  transmits the video data or audio data in the form of packet data (video packet or audio packet) to the coordinator  106  by a network, wherein the video data or audio data is stored in the storage unit. Then, the coordinator  106  transmits the received packet to the wireless signal transmission device  104  by the network. The wireless signal transmission device  104  stores the packet data received from the coordinator  106  in the storage unit  122 . The processing unit  120  executes a program in the memory  124  to read the MAC address of every electronic display device  102  corresponding to every received packet, and record the plurality of the read MAC address in an access control address list. In other words, the access control address list has the MAC address corresponding to every packet data stored in the storage unit  122 . For example, the access control address list comprises MAC addresses of all electronic display devices  102  (i.e. all electronic display devices  102  have to be updated by packet data), or MAC addresses for partial electronic display devices  102  (i.e. partial electronic display devices  102  have to be updated by packet data). 
         [0023]    Then, the wireless communication module  118  of the wireless signal transmission device  104  broadcasts the access control address list to all electronic display devices  102 . When the wireless communication module  110  of the electronic display device  102  receives the access control address list, the wireless communication module  110  transmits an interrupt signal to the processing unit  112  and the power supply unit  111 . The processing unit  112  and the power supply unit  111  wake up from a sleep state when receiving the interrupt signal, and then receive the access control address list from the wireless communication module  110 . Then, the processing unit  112  executes a program in the memory  116  for contrasting whether the access control address list has the MAC address of the electronic display device  102 . When the access control address list doesn&#39;t have the media access control address of the electronic display device  102 , the processing unit  112  and the power supply unit  111  will go back to sleep mode. When the access control address list has the MAC address of the electronic display device  102 , the processing unit  112  makes the wireless communication module  110  transmit an acknowledge (ACK) message to the wireless signal transmission device  104 . 
         [0024]    When the wireless communication module  118  of the wireless signal transmission device  104  receives the ACK message from the electronic display device  102  in a preset time, the wireless signal transmission device  104  will modify the method of transmitting packet data from broadcast mode to unicast mode, and transmit the corresponded video packet and audio packet stored in the storage unit  122  to the electronic display device  102  corresponding to the ACK message by the wireless communication module  118 . At this time, the transmitted packet data would comprise the MAC address of the electronic display device  102 , so if the transmitted packet data doesn&#39;t comprise the MAC address of the electronic display device  102 , the electronic display device  102  doesn&#39;t receive the packet data. After the electronic display device  102  receives the packet data transmitted from the wireless communication module  118 , the processing unit  112  transmits the video data of the packet data to the display unit  114  and transmits the audio data to the voice module  115 . It updates the video file displayed in the display unit  114  with received video data, and/or the audio file played in the voice module  115  with received audio data. In addition, the processing unit  120  of the wireless signal transmission device  104  will delete the MAC address of the electronic display device  102  from the access control address list, wherein the packet data of the electronic display device  102  is updated. 
         [0025]    When the wireless communication module  118  of the wireless signal transmission device  104  doesn&#39;t receive the ACK message from the electronic display device  102  in a preset time, the processing unit  120  will determine whether all electronic display devices  102  are updated by the packet data according to the access control address list. If some electronic display devices  102  in the access control address list are still not updated by the packet data, the wireless communication module  118  of the wireless signal transmission device  104  will continuously broadcast the access control address list to all electronic display devices  102 . If all electronic display devices  102  in the access control address list have been updated by the packet data, the wireless communication module  118  of the wireless signal transmission device  104  will stop broadcasting the access control address list to all electronic display devices  102 . 
         [0026]      FIG. 1  is an embodiment of a single signal transmission group. According to the concept illustrated in  FIG. 1 , it could develop the multi-signal transmission groups.  FIG. 2  is schematic diagram illustrating the signal transmission system of an electronic display device according to another embodiment of the invention. In the embodiment, there are groups A, B, and C, wherein the signal transmission method of each group is the same as in  FIG. 1 . Multi-signal transmission groups can support each other by the coordinator  106 . For example, when the wireless signal transmission device  104 A in group A has been converted to operate in unicast mode and updating one of the electronic display devices in group A by transmitting the packet data, if the wireless signal transmission device  104 B in group B is in idle mode, the wireless signal transmission device  104 B will be switched to unicast mode by the coordinator  106 , and the wireless signal transmission device  104 B updates the electronic display devices in group A which still have not been updated by transmitting the packet data. 
         [0027]      FIGS. 3A-3B  are a flowchart of the transmission method according to an embodiment of the invention, wherein the method is appropriate for using in the environment of an electronic display device system. In step S 202 , a plurality of packet data is received and stored in the storage unit, wherein the packet data comprise the video data and/or audio data corresponding to each electronic display device, and the packet data comprise the product price, a text description or product-selling description. In step S 204 , the MAC address of each electronic display device corresponding to the received packet data is read, and the read MAC address are recorded in an access control address list. In other words, the access control address list has the MAC address corresponding to every packet data stored in the storage unit. For example, the access control address list comprises the MAC address of all electronic display devices (i.e. all electronic display devices have to be updated by packet data), or the MAC address of partial electronic display devices (i.e. partial electronic display devices have to be updated by packet data). In step S 206 , the access control address list is broadcast to all electronic display devices. In step S 208 , it is determined whether the ACK message is received from the electronic display devices in a preset time. When the ACK message is received from an electronic display device in a preset time, step S 210  is executed; when the ACK message is not received from an electronic display device in a preset time, step S 212  is executed. In step S 210 , the method of transmitting packet data is changed from broadcast to unicast, and the packet data of the electronic display device corresponding to the ACK message is transmitted to the electronic display devices, wherein the packet data is stored in the storage unit. In step S 214 , the MAC address of the electronic display device which is updated by the packet data is removed from the access control address list, and a deleted message is returned to step S 204  for updating the access control address list. 
         [0028]    In step S 212 , it is determined whether all electronic display devices in the access control address list have been updated by the packet data according to the access control address  15 , list. When there are electronic display devices in the access control address list that have not been updated, step S 206  is executed; when all electronic display devices in the access control address list are updated, step S 216  is executed to stop the flowchart of  FIGS. 3A-3B . 
         [0029]      FIG. 4  is a flowchart of the transmission method according to an embodiment of the invention, wherein the method is appropriate for using in the environment of an electronic display device. In step S 302 , when the access control address list broadcast from the wireless signal transmission device is received, for example, by the electronic display device  102 , an interrupt signal is transmitted for waking up the processing unit and power supply unit from a sleep state. In step S 304 , a program in the memory is executed for determining whether the access control address list has the MAC address of the electronic display device. When the access control address list doesn&#39;t have the MAC address of the electronic display device, step S 306  is executed; when the access control address list has the MAC address of the electronic display device, step S 308  is executed. In step  306 , the processing unit and power supply unit are in a sleep state again. In step  308 , an ACK message is transmitted to the wireless signal transmission device. In step S 310 , the packet data transmitted from the wireless signal transmission device are received. In step S 312 , the video data or audio data in the packet data is transmitted to the display unit and voice module for updating the video and audio displayed by the electronic display device by the packet data. 
         [0030]    The transmission system and method disclosed in the invention can increase the throughput and size of the transmission data, and provide a transfer guarantee in the environment of an electronic display device system. 
         [0031]    The above paragraphs describe many aspects of the invention. Obviously, the teaching of the invention can be accomplished by many methods, and any specific configurations or functions in the disclosed embodiments only present a representative condition. Those who are skilled in this technology can understand that all of the disclosed aspects in the invention can be applied independently or be incorporated. 
         [0032]    While the invention has been described by way of example and in terms of preferred embodiment, it is to be understood that the invention is not limited thereto. Those who are skilled in this technology can still make various alterations and modifications without departing from the scope and spirit of this invention. Therefore, the scope of the present invention shall be defined and protected by the following claims and their equivalents.