Data display system, data relay device, data relay method, data system, sink device, and data read method

Abstract

A repeater comprises an EDID memory to store a control data and a memory control unit. The memory control unit is configured to make access to the EDID memory to read the control data therefrom, store the read control data into the EDID memory and, when access is made to the EDID memory by the set-top box, transfer the control data stored in the EDID memory to the set-top box. In this case, the memory control unit outputs an inhibiting signal to a set-top box to inhibit it from making access to the EDID memory until the completion of an operation of storing the control data from the EDID memory in the set-top box into the EDID memory in the repeater.

What is claimed is:  
     
         1 . A data display system comprising: 
 a display unit which stores control data representing display attributes; and    a data relay device configured to make access to the display unit to read the control data therefrom, store the read control data into a first memory and, when access is made to the first memory by a first source device, transfer the read control data stored in the first memory to the first source device after the completion of storing the read control data from the display unit into the first memory.    
     
     
         2 . The data display system according to  claim 1 , wherein the data relay device outputs an inhibiting signal to inhibit access to the first memory to the first source device until the completion of storing the read control data from the display unit into the first memory.  
     
     
         3 . The data display system according to  claim 1 , wherein a plurality of data relay devices is connected in cascade between the first source device and the display unit.  
     
     
         4 . The data display system according to  claim 1 , further comprising: 
 a first data bus which transfers the control data stored in the display unit to the data relay device; and    a second data bus which transfers the read control data stored in the first memory in the data relay device to the first source device.    
     
     
         5 . The data display system according to  claim 1 , further comprising: 
 a first data bus which transfers the control data stored in the display unit to the data relay device; and    a second data bus which transfers the read control data stored in the first memory in the data relay device to the first source device, and wherein 
 the data relay device has terminals connected to the second data bus to control the conduction/nonconduction of the second data bus according to the presence or absence of access to the first memory by the data relay device.  
   
     
     
         6 . The data display system according to  claim 1 , further comprising: 
 a first serial link which transfers the control data stored in the display unit to the data relay device; and    a second serial link which transfers the read control data stored in the first memory in the data relay device to the first source device, and wherein 
 the data relay device has terminals connected to the second serial link to control the conduction/nonconduction of the second serial link according to the presence or absence of access to the first memory by the data relay device and switching elements which perform on-off control of the second serial link.  
   
     
     
         7 . The data display system according to  claim 2 , further comprising: 
 a hot plug line which is connected between the data relay device and the first source device and indicates the active/inactive state of the data relay device, and wherein 
 the data relay device outputs the inhibiting signal to the first source device when the hot plug line indicates the inactive state.  
   
     
     
         8 . The data display system according to  claim 1 , further comprising: 
 a control unit which is provided in the first source device and makes access to the first memory in the data relay device to acquire the read control data stored therein.    
     
     
         9 . The data display system according to  claim 1 , further comprising: 
 a second source device which encodes a second digital signal on the basis of the read control data to output a second serial digital signal;    a second memory, provided in the data relay device, which stores the control data transferred from the display unit; and    a control unit provided in the data relay device and configured to make access to the display unit to store the control data obtained from the display unit into the second memory and, when access is made to the second memory by the second source device, transfer the control data stored in the second memory to the second source device after the completion of storing the control data from the display unit into the second memory.    
     
     
         10 . The data display system according to  claim 9 , wherein the data relay device resets data transmission from the first source device to the display unit and commences the operation of the control unit if the data relay device detects that the power state of the second source device has become active while data is relayed from the first source device to the display unit.  
     
     
         11 . The data display system according to  claim 1 , wherein the first source device encodes a first digital signal on the basis of the read control data and outputs a serial digital signal, and the data relay device relays the serial digital signal from the first source device to the display unit.  
     
     
         12 . A data relay device, provided between a display unit which stores control data representing display attributes and a first source device, comprising: 
 a first memory configured to store the control data representing display attributes of the display unit; and    a first control unit configured to make access to the display unit to read the control data therefrom, store the read control data into the first memory and, when access is made to the first memory by the first source device, transfer the read control data stored in the first memory to the first source device after the completion of storing the control data from the display unit into the first memory.    
     
     
         13 . The data relay device according to  claim 12 , wherein the first control unit outputs an inhibiting signal to inhibit access to the first memory to the first source device until the completion of storing the control data from the display unit into the first memory.  
     
     
         14 . The data relay device according to  claim 12 , further comprising: 
 a first data bus which transfers the control data from the display unit to the first memory; and    a second data bus which transfers the read control data stored in the first memory to the first source device.    
     
     
         15 . The data relay device according to  claim 12 , further comprising: 
 a first data bus which transfers the control data from the display unit to the first memory; and    a second data bus which transfers the read control data stored in the first memory to the first source device, and wherein 
 the first control unit has terminals connected to the second data bus to control the conduction/nonconduction of the second data bus according to the presence or absence of access to the first memory by the first control unit.  
   
     
     
         16 . The data relay device according to  claim 12 , further comprising: 
 a first serial link which transfers the control data from the display unit to the first memory; and    a second serial link which transfers the read control data stored in the first memory to the first source device, and wherein 
 the first control unit has terminals connected to the second serial link to control the conduction/nonconduction of the second serial link according to the presence or absence of access to the first memory by the first control unit and switching elements which perform on-off control of the second serial link.  
   
     
     
         17 . The data relay device according to  claim 13 , further comprising: 
 a hot plug line connected to the first source device to indicate whether access to the first memory is inhibited or not, and wherein 
 the inhibiting signal is output to the first source device over the hot plug line.  
   
     
     
         18 . A data relay method for relaying data between a display unit which stores control data representing display attributes and a first source device, comprising: 
 making access to the display unit to read the control data therefrom;    storing the read control data into a first memory; and    in response to access to the first memory by the first source device, transferring the read control data stored in the first memory to the first source device after the completion of storing the control data from the display unit into the first memory.    
     
     
         19 . The data relay method according to  claim 18 , further comprising: 
 detecting the power state of the first source device before acquiring the control data from the display unit; and    outputting a signal informing that the display unit is in the active state after the detection.    
     
     
         20 . The data relay method according to  claim 18 , further comprising: 
 resetting data transmission from the first source device to the display unit when detecting that the power state of a second source device has become active during data relay from the first source device to the display unit;    making access to the display unit to acquire the control data after the resetting;    storing the control data into a second memory; and    transferring the control data stored in the second memory in response to access to the second memory by the second source device after the completion of storing the control data from the display unit into the second memory.    
     
     
         21 . The data relay method according to  claim 19 , wherein access to the first memory by the first source device is prohibited by causing a serial link connected between the first source device and the first memory nonconductive.  
     
     
         22 . A data system comprising: 
 a source device configured to output a digital signal; and    a sink device which comprises a memory configured to store display identification data and transfers the display identification data stored in the memory to the source device after the completion of storing the display identification data, when access is made to the memory by the source device.    
     
     
         23 . A sink device comprising: 
 a memory configured to store display identification data; and    a control unit which inputs data from a source device and transfers the display identification data stored in the memory to the source device after the completion of storing the display identification data when access is made to the memory by the source device.    
     
     
         24 . A data read method comprising: 
 writing data into a memory; and    allowing a source device to read the data from the memory after the completion of writing the data into the memory.    
     
     
         25 . A data read method according to  claim 24 , 
 in which allowing the source device to read the data is used a hot plug line connected to the source device.    
     
     
         26 . A data read method comprising: 
 writing data into a memory; and    prohibiting a source device from reading the data from the memory;    allowing the source device to read the data from the memory, after the completion of writing the data into the memory.    
     
     
         27 . A data read method according to  claim 26 , 
 in which prohibiting the source device from reading the data and allowing the source device to read the data are used a hot plug line connected to the source device.