Power reception device and electronic apparatus

Abstract

A power reception device includes a power reception antenna used for communication and electric power reception; a rectifier circuit connected to the antenna, the rectifier circuit converting into direct current voltage, electric power received by the antenna, and the direct current voltage is output and supplied to a load; a communication section which communicates via the antenna; a switch circuit connected between the antenna and the communication section, wherein the switch circuit is transitable between a conductive state in which the communication section is electrically connected to the antenna and a cut-off state in which the communication section is electrically disconnected from the antenna; and a switch control section connected to the rectifier circuit. The switch control section transitions the switch circuit into the cut-off state when the direct current voltage output from the rectifier circuit exceeds a first threshold in association with start of the electric power reception by the antenna, and the switch control section performs transition of the switch circuit into the conductive state when the direct current voltage falls below a second threshold different from the first threshold. During signal sending by the communication section via the antenna, the switch control section does not transition the switch circuit into the cut-off state even when the direct current voltage output from the rectifier circuit exceeds the first threshold; and during the signal sending by the communication section via the antenna, the switch control section transitions the switch circuit into the cut-off state when the direct current voltage exceeds a third threshold larger than the first threshold.

1 . A power reception device comprising:
 a power reception antenna used for both communication and electric power reception;   a rectifier circuit connected to the power reception antenna, wherein the rectifier circuit converts, into direct current voltage, electric power received by the power reception antenna, and the direct current voltage is output and supplied to a load;   a communication section which communicates via the power reception antenna;   a switch circuit connected between the power reception antenna and the communication section, wherein the switch circuit is transitable between a conductive state in which the communication section is electrically connected to the power reception antenna and a cut-off state in which the communication section is electrically disconnected from the power reception antenna; and   a switch control section connected to the rectifier circuit, wherein the switch control section performs transition of the switch circuit into the cut-off state when the direct current voltage output from the rectifier circuit exceeds a first threshold in association with start of the electric power reception by the power reception antenna, and the switch control section performs transition of the switch circuit into the conductive state when the direct current voltage falls below a second threshold different from the first threshold, wherein:   during signal sending by the communication section via the power reception antenna, the switch control section does not perform the transition of the switch circuit into the cut-off state even when the direct current voltage output from the rectifier circuit exceeds the first threshold; and   during the signal sending by the communication section via the power reception antenna, the switch control section performs the transition of the switch circuit into the cut-off state when the direct current voltage exceeds a third threshold larger than the first threshold.   
     
     
         2 . The power reception device as recited in  claim 1 , wherein:
 the power reception device is configured such that when the power reception antenna starts the electric power reception, the direct current voltage output from the rectifier circuit rises to reach a maximum value of voltage output from the rectifier, at which the direct current voltage output from the rectifier circuit is not supplied to the load, and subsequently lowers to a supplied value of voltage output from the rectifier, which is smaller than the maximum value and at which the direct current voltage output from the rectifier circuit is supplied to the load; and   the first threshold is larger than the supplied value and smaller than the maximum value.   
     
     
         3 . The power reception device as recited in  claim 2 , wherein the second threshold is smaller than the supplied value. 
     
     
         4 . The power reception device as recited in  claim 1 , wherein the communication section notifies the switch control section, by a control signal, that the signal sending via the power reception antenna is performed. 
     
     
         5 . The power reception device as recited in  claim 1 , wherein:
 the power reception device is configured to perform communication with load modulation by using the power reception antenna; and   during performance of the communication with load modulation, the switch control section performs the transition of the switch circuit into the cut-off state under a case where the direct current voltage exceeds the first threshold.   
     
     
         6 . The power reception device as recited in  claim 1 , wherein the power reception device further comprises a DC-DC converter connected between the rectifier circuit and the load. 
     
     
         7 . The power reception device as recited in  claim 1 , wherein:
 the switch circuit includes an in-line switch and a ground switch;   the in-line switch is connected in series between the power reception antenna and the communication section; and   the ground switch is connected between a connection point, which is between the power reception antenna and the communication section, and ground.   
     
     
         8 . The power reception device as recited in  claim 7 , wherein each of the in-line switch and the ground switch is formed of an N-channel FET.