External accessory to be attached to electronic apparatus and system

Abstract

An external accessory that can be attached to and detached from an electronic apparatus equipped with a power source unit includes: a first power receiving unit that receives power from the power source unit of the electronic apparatus; a second power receiving unit that receives power from the power source unit of the electronic apparatus; a decision-making unit that makes a decision as to whether or not the first power receiving unit is receiving power; a function execution unit that executes a predetermined function by using power received at one of the first power receiving unit and the second power receiving unit; and a control unit that engages the function execution unit in operation continuously when an affirmative decision is made by the decision-making unit, and engages the function execution unit in operation intermittently when a negative decision is made by the decision-making unit.

1 . (canceled) 
     
     
         2 . An accessory that can be attached to and detached from an electronic apparatus that has a first power line and a second power line, the accessory comprising:
 a first power receiver that is configured to receive power through the first power line of the electronic apparatus;   a second power receiver that is configured to receive power through the second power line of the electronic apparatus;   an execution unit that executes a predetermined function; and   a control unit that, when receipt of the power by the first power receiver is suspended, controls the execution unit with the power received by the second power receiver.   
     
     
         3 . The accessory according to  claim 2 , wherein
 in the control unit, control of the execution unit with the power received by the second power receiver limits the function more than control of the execution unit with the power received by the first power receiver.   
     
     
         4 . The accessory according to  claim 2 , wherein
 when the control unit controls the execution unit with the power received by the second power receiver, and when the function is executed a predetermined number of times, the function is suspended.   
     
     
         5 . The accessory according to  claim 4 , wherein
 the control unit changes the predetermined number of times depending on capacity of the power received by the second power receiver.   
     
     
         6 . The accessory according to  claim 4 , wherein:
 the execution unit executes a position measuring function, and   the control unit changes the predetermined number of times according to movement information of the accessory obtained by the position measuring function.   
     
     
         7 . The accessory according to  claim 2 , wherein
 the control unit limits the function of the execution unit according to an operation state of the electronic apparatus.   
     
     
         8 . The accessory according to  claim 7 , wherein:
 the electronic apparatus is an imaging apparatus in which an imaging optical system can be attached to and detached from the electronic apparatus, and   the control unit limits the function of the execution unit if the imaging optical system is not attached to the imaging apparatus.   
     
     
         9 . The accessory according to  claim 2 , wherein
 the first power receiver is configured to receive power from the second power line through the first power line.