Video signal processing circuit and computer system

Abstract

A video signal processing circuit, in which a horizontal synchronizing signal is separated from an input analog video signal by a synchronism separating circuit, whether a “H” period of the horizontal synchronizing signal continues for more than a prespecified period of time or not is checked by a synchronizing signal monitoring counter, and power supply to an A/D converter is controlled thereby according to a result the confirmation.

1. A video signal processing circuit comprising:
 an A/D converter converting an input analog video signal to a digital video signal in response to a power supply;    a synchronism separating unit separating a synchronizing signal from said input analog video signal;    a monitoring unit monitoring a disturbance of the synchronizing signal and time for which the disturbance continues; and    a power supply unit supplying power to said A/D converter, wherein said power supply unit stops the power supply to said A/D converter when the time for which the disturbance continues exceeds a predetermined time period that is shorter than the time period for which a normal horizontal synchronizing signal continues.    
     
     
       2. A computer system connected to an external device and executing image processing according to an analog video signal inputted from the external device comprising:
 a video signal processing circuit generating a digital video signal according to an analog video signal inputted from the external device;    an image processing circuit executing image processing according to a digital video signal generated by said video signal processing circuit; and    a power supply unit supplying power within the computer system, wherein said video signal processing circuit comprises:    an A/D converter converting an input analog video signal to a digital video signal in response to a power supply,    a synchronism separating unit separating a synchronizing signal from said input analog video signal,    a monitoring unit monitoring a disturbance of the synchronizing signal and time for which the disturbance continues, and    a power supply unit supplying the power to said A/D converter, wherein said power supply unit stops the power supply to said A/D converter when the time for which the disturbance continues exceeds a predetermined time period that is shorter than the time period for which a normal horizontal synchronizing signal continues.    
     
     
       3. A method, comprising:
   converting a video signal at an A/D converter using power from a power supply;        monitoring a time for which a disturbance of a synchronizing signal of the video signal continues; and        stopping the power if the time exceeds a predetermined time that is shorter than a sampling cycle for a normal video signal.      
     
     
       4. The method of  claim 3  wherein the monitoring comprises monitoring a horizontal synchronizing pulse determined at least in part on a horizontal synchronizing signal.  
     
     
       5. The method of  claim 3  wherein the stopping the power comprises stopping the power to the A/D converter if the time for which the disturbance continues exceeds a predetermined period that is shorter than the time period for which a horizontal synchronizing signal of the video signal continues.  
     
     
       6. The method of  claim 3 , further comprising:
   monitoring the synchronizing signal for predetermined conditions; and        stopping the power if the predetermined conditions of the synchronizing signal are not satisfied, wherein the predetermined conditions comprise conditions under which a video signal and character information can be reproduced.      
     
     
       7. The method of  claim 3  wherein the synchronizing signal comprises a horizontal synchronizing signal, the method further comprising:
   monitoring the horizontal synchronizing signal; and    
   stopping the power if the horizontal synchronizing signal is not continuous for at least a second predetermined period of time.    
 
     
     
       8. The method of  claim 3  wherein the method is carried out in a computer.  
     
     
       9. The method of  claim 8  wherein the computer is a notebook computer.  
     
     
       10. The method of  claim 3  wherein the sampling cycle for a normal video signal is approximately  58 . 8  μs.  
     
     
       11. A system, comprising:
   means for converting a video signal from an analog signal to a digital signal using power from power supply means;        means for monitoring a time for which a disturbance of a synchronizing signal of the video signal continues; and        means for stopping the power if the time exceeds a predetermined time that is shorter than a sampling cycle for a normal video signal.      
     
     
       12. The system of  claim 11  wherein the means for monitoring is further configured to monitor a horizontal synchronizing pulse determined at least in part on a horizontal synchronizing signal.  
     
     
       13. The system of  claim 11  wherein the means for stopping is further configured to stop the power to the converting means if the time for which the disturbance continues exceeds a predetermined time period that is shorter than the time period for which a horizontal synchronizing signal continues.  
     
     
       14. The system of  claim 11  wherein the means for monitoring is further configured to monitor the synchronizing signal for predetermined conditions of the synchronizing signal, and wherein the means for stopping is further configured to stop the power if the predetermined conditions of the synchronizing signal are not satisfied.  
     
     
       15. The system of  claim 11  wherein:
   the synchronizing signal comprises a horizontal synchronizing signal;    
   the means for monitoring is further configured to monitor the horizontal synchronizing signal; and    
   the means for stopping is further configured to stop the power if the horizontal synchronizing signal is continuous for less than a second predetermined period of time.    
 
     
     
       16. The system of  claim 11  wherein the predetermined time is shorter than about  58 . 8  μs.  
     
     
       17. A video signal processing circuit, comprising:
   an A/D converter configured to convert an analog video signal to a digital video signal using power from a power supply; and        a power control unit configured to monitor a time for which a disturbance of a synchronizing signal of the video signal continues and is configured to stop the power if the time exceeds a predetermined time that is shorter than a cycle for a normal video signal.      
     
     
       18. The video signal processing circuit of  claim 17  wherein the power control unit is further configured to monitor a horizontal synchronizing pulse determined at least in part on a horizontal synchronizing signal.  
     
     
       19. The video signal processing circuit of  claim 17  wherein the power control unit is further configured to supply power to the A/D converter, wherein the power control unit is further configured to stop the power supply to the A/D converter if the time for which the disturbance continues exceeds a predetermined time period that is shorter than the time period for which a horizontal synchronizing signal continues.  
     
     
       20. The video signal processing circuit of  claim 17  wherein the power control unit is further configured to monitor the synchronizing signal for predetermined conditions of the synchronizing signal and is further configured to stop the power if the predetermined conditions of the synchronizing signal are not satisfied.  
     
     
       21. The video signal processing circuit of  claim 17  wherein the synchronizing signal comprises a horizontal synchronizing signal, wherein the monitoring unit is further configured to monitor the horizontal synchronizing signal, and wherein the power control unit is further configured to stop the power if the horizontal synchronizing signal is continuous for less than a second predetermined period of time.  
     
     
       22. The video signal processing circuit of  claim 17  wherein the cycle for a normal video signal is approximately  58 . 8  μs.  
     
     
       23. A computer system, comprising:
   a video signal processing circuit configured to generate a digital video signal based at least in part on an analog video signal inputted from an external device, wherein the video signal processing circuit comprises:      a power supply;        an A/D converter configured to convert the input analog video signal to a digital video signal using power from the power supply; and        a power control unit configured to monitor a time for which a disturbance of a synchronizing signal of the video signal continues and is further configured to stop the power if the time exceeds a predetermined time, wherein the predetermined time is shorter than a sampling cycle for a complex video signal.        
     
     
       24. The computer system of  claim 23  wherein the power control unit is further configured to monitor a horizontal synchronizing pulse determined at least in part on a horizontal synchronizing signal.  
     
     
       25. The computer system of  claim 23  wherein the power control unit is further configured to supply power to the A/D converter, wherein the power control unit is further configured to stop the power supply to the A/D converter if the time for which the disturbance continues exceeds a predetermined time period that is shorter than the time for which a horizontal synchronizing signal continues.  
     
     
       26. The computer system of  claim 23  wherein the power control unit is further configured to monitor the synchronizing signal for predetermined conditions of the synchronizing signal, and is further configured to power off the power supply if the predetermined conditions of the synchronizing signal are not satisfied.  
     
     
       27. The computer system of  claim 23  wherein the synchronizing signal comprises a horizontal synchronizing signal, and wherein the power control unit is further configured to monitor the horizontal synchronizing signal, and is further configured to power off the power supply if the horizontal synchronizing signal is not continuous for at least a second predetermined period of time.  
     
     
       28. The computer system of  claim 23  wherein the computer is a notebook computer.  
     
     
       29. The computer system of  claim 23  wherein the sampling cycle for a complex video signal is approximately  58 . 8  μs.  
     
     
       30. A method, comprising:
   converting a video signal at an A/D converter using power from a power supply;        monitoring whether an “H”  ( high )  period of a horizontal synchronizing signal separated by a synchronism separating unit continues for more than a pre - specified period of time or not; and        supplying power to said A/D converter only when it is confirmed that the “H” period continues for more than said pre - specified period of time wherein the pre - specified time is shorter than a normal complex video signal.      
     
     
       31. The method of  claim 30 , further comprising:
   monitoring a time for which a disturbance of a synchronizing signal of the video signal continues; and        stopping the power if the monitored disturbance time exceeds a predetermined time.      
     
     
       32. The method of  claim 31  wherein the stopping the power comprises stopping the power to the A/D converter if the time for which the disturbance continues exceeds a predetermined period that is shorter than the time period for which a horizontal synchronizing signal of the video signal continues.  
     
     
       33. The method of  claim 30  wherein the method is carried out in a computer.  
     
     
       34. The method of  claim 33  wherein the computer is a notebook computer.  
     
     
       35. The method of  claim 30  wherein the pre- specified time is shorter than about  58 . 8  μs.    
     
     
       36. A system, comprising:
   means for converting a video signal from an analog signal to a digital signal using power from power supply means;        means for monitoring whether an “H”  ( high )  period of a horizontal synchronizing signal separated by a synchronism separating unit continues for more than a pre - specified period of time or not; and        means for supplying power to said means for converting only when it is confirmed that the “H” period continues for more than said pre - specified period of time, wherein the pre - specified time is shorter than a sampling cycle for a normal video signal.      
     
     
       37. The system of  claim 36 , further comprising:
   means for monitoring a time for which a disturbance of a synchronizing signal of the video signal continues; and        means for stopping the power if the monitored disturbance time exceeds a predetermined time.      
     
     
       38. The system of  claim 37  wherein the means for stopping is further configured to stop the power to the converting means if the time for which the disturbance continues exceeds a predetermined time period that is shorter than the time period for which a horizontal synchronizing signal continues.  
     
     
       39. The system of  claim 36  wherein the sampling cycle for a normal video signal is approximately  58 . 8  μs.  
     
     
       40. A video signal processing circuit, comprising:
   an A/D converter configured to convert an analog video signal to a digital video signal using power from a power supply;        a monitoring unit capable of monitoring whether the “H”  ( high )  period of a horizontal synchronizing signal separated by a synchronism separating unit continues for more than a pre - specified period of time or not; and        a power supply unit capable of supplying power to said A/D converter only when it is confirmed by the monitoring unit that the “H” period continues for more than said pre - specified period of time that is shorter than a sampling cycle for a normal complex video signal.      
     
     
       41. The video signal processing circuit of  claim 40  wherein the monitoring unit is further configured to monitor disturbance of the horizontal synchronizing signal and time for which the disturbance continues, and wherein the power supply unit is further configured to stop the power supply to said A/D converter if the time for which the disturbance continues exceeds a predetermined time period that is shorter than the time period for which a horizontal synchronizing signal continues.  
     
     
       42. The video signal processing circuit of  claim 40  wherein the sampling cycle for a normal complex video signal comprises approximately  58 . 8  microseconds.