Accessory device, imaging apparatus, and communication control program

Abstract

An imaging apparatus that provides, between itself and an accessory device, a notification channel used for notification from the imaging apparatus to the accessory device, a first data communication channel used in data transmission from the accessory device to the imaging apparatus, and a second data communication channel used in data transmission from the imaging apparatus to the accessory device. An accessory control unit transmits data via the first data communication channel in response to having received a transmission request signal via the notification channel, and selectively adds, to the data, a communication standby request for keeping a transmission request signal from being transmitted from the imaging apparatus to the accessory device.

1 . An accessory device detachably mountable to an imaging apparatus, the accessory device comprising:
 an accessory communication circuitry that provides, between itself and the imaging apparatus, a notification channel used for notification from the imaging apparatus to the accessory device, an accessory data communication channel used for data transmission from the accessory device to the imaging apparatus, and an imaging apparatus data communication channel used for data transmission from the imaging apparatus to the accessory device; and   an accessory control circuitry configured to control the accessory communication circuitry.   
     
     
         2 . The accessory device according to  claim 1 ,
 wherein the accessory control circuitry transmits a first data to the imaging apparatus via the accessory data communication channel, in response to receiving, via the notification channel, a transmission request signal, the transmission request signal being a signal for requesting transmission of data from the accessory device to the imaging apparatus, and receives, via the imaging apparatus data communication channel, a second data transmitted, to the accessory device, from the imaging apparatus in response to the imaging apparatus starting to receive the first data.   
     
     
         3 . The accessory device according to  claim 2 ,
 wherein a period to transmit the first data and a period to receive the second data are partially overlapped.   
     
     
         4 . The accessory device according to  claim 2 ,
 wherein the accessory control circuitry starts receiving of the second data after starting transmission of the first data.   
     
     
         5 . The accessory device according to  claim 4 ,
 wherein the accessory control circuitry starts receiving of the second data after transmitting a start bit included in the first data.   
     
     
         6 . The accessory device according to  claim 2 ,
 wherein the transmission request signal is expressed by changing a voltage level of the notification channel.   
     
     
         7 . The accessory device according to  claim 6 ,
 wherein the accessory control circuitry transmits the first data within a predetermined period after the voltage level of the notification channel changes.   
     
     
         8 . The accessory device according to  claim 6 ,
 wherein the transmission request signal is expressed by changing the voltage level of the notification channel from a first level to a second level which is different from the first level, and   the accessory control circuitry transmits a third data to the imaging apparatus, via the accessory data communication channel, in a case where the voltage of the notification channel is the second level after transmitting the first data.   
     
     
         9 . The accessory device according to  claim 2 ,
 wherein the accessory device performs communication with the imaging apparatus by switching between a data format where data frames are transmitted without a communication standby period, and a data format where data frames are transmitted with a communication standby period.   
     
     
         10 . The accessory device according to  claim 9 ,
 wherein in a case where the communication format, between itself and the imaging apparatus, is the data format where data frames are transmitted with the communication standby period, a number of data which the accessory control circuitry transmitted to the imaging apparatus before the communication standby period and a number of data which the accessory control circuitry received from the imaging apparatus before the communication standby period are the same number.   
     
     
         11 . The accessory device according to  claim 9 ,
 wherein the transmission request signal is expressed by changing the voltage level of the notification channel from a first level to a second level which is different from the first level, and   the communication standby period is expressed by the voltage level of the notification channel in the first level.   
     
     
         12 . The accessory device according to  claim 9 ,
 wherein the accessory control circuitry pauses data transmission to the imaging apparatus while the communication standby request event occurring in the accessory device.   
     
     
         13 . The accessory device according to  claim 2 ,
 wherein the accessory device performs an asynchronous communication with the imaging apparatus.   
     
     
         14 . The accessory device according to  claim 2 ,
 wherein the accessory device is communicable with the imaging device by switching communication methods between a clock-synchronized communication method synchronized with clock signals and an asynchronous communication method, and   the accessory control circuitry receives, via the notification channel, the clock signals transmitted from the imaging device in the clock-synchronized communication method, and receives, via the notification channel, the transmission request signal in the asynchronous communication method.   
     
     
         15 . The accessory device according to  claim 2 ,
 wherein the accessory device comprises an imaging optical system capable of forming a subject image on an imaging device of the imaging apparatus.   
     
     
         16 . An imaging apparatus to which an accessory device is detachably mounted, the apparatus comprising:
 an imaging apparatus communication circuitry provided with, between itself and the accessory device, a notification channel used for notification from the imaging apparatus to the accessory device, an accessory data communication channel used for data transmission from the accessory device to the imaging apparatus, and an imaging apparatus data communication channel used for data transmission from the imaging apparatus to the accessory device; and   an imaging apparatus control circuitry configured to control the imaging apparatus communication circuitry.   
     
     
         17 . The imaging apparatus according to  claim 16 , wherein the imaging apparatus control circuitry transmits, via the notification channel, a transmission request signal to the accessory device, the transmission request signal being a signal for requesting data transmission from the accessory device to the imaging apparatus, and transmits a second data to the accessory device, via the imaging apparatus data communication channel, in response to starting to receive a first data transmitted, to the imaging apparatus, from the accessory device according to the transmission request signal. 
     
     
         18 . The imaging apparatus according to  claim 17 ,
 wherein a period to receive the first data and a period to transmit the second data are partially overlapped.   
     
     
         19 . The imaging apparatus according to  claim 17 ,
 wherein the imaging apparatus control circuitry starts transmitting the second data in response to reception of a start bit included in the first data.   
     
     
         20 . The imaging apparatus according to  claim 17 ,
 wherein the imaging apparatus control circuitry transmits the transmission request signal to the accessory device by changing a voltage level of the notification channel.   
     
     
         21 . The imaging apparatus according to  claim 20 ,
 wherein the imaging apparatus control circuitry transmits the transmission request signal by changing the voltage level of the notification channel from a first level to a second level which is different from the first level, and   the imaging apparatus control circuitry receives a third data from the accessory device, via the accessory data communication channel, by maintaining the voltage of the notification channel at the second level during and after receiving the first data.   
     
     
         22 . The imaging apparatus according to  claim 17 ,
 wherein the imaging apparatus performs communication with the accessory device by switching between a data format where data frames are transmitted without a communication standby period, and a data format where data frames are transmitted with a communication standby period.   
     
     
         23 . The imaging apparatus according to  claim 22 ,
 wherein in a case the communication format, between itself and the accessory device, is the data format where data frames are transmitted with the communication standby period, a number of data which the imaging apparatus control circuitry transmitted to the accessory device before the communication standby period, and a number of data which the imaging apparatus control circuitry received from the accessory device before the communication standby period are the same number.   
     
     
         24 . The imaging apparatus according to  claim 22 ,
 wherein the imaging apparatus control circuitry transmits the transmission request signal by changing the voltage level of the notification channel from a first level to a second level which is different from the first level, and   the imaging apparatus control circuitry notifies the communication standby period to the accessory device by setting the voltage level of the notification channel to the first level.   
     
     
         25 . The imaging apparatus according to  claim 17 ,
 wherein the imaging apparatus control circuitry performs an asynchronous communication with the accessory device.   
     
     
         26 . The imaging apparatus according to  claim 17 ,
 wherein the imaging apparatus is communicable with the accessory device by switching communication methods between a clock-synchronized communication method synchronized with clock signals and an asynchronous communication method, and   the imaging apparatus control circuitry transmits the clock signals to the accessory device, via the notification channel, in the clock-synchronized communication method, and transmits the transmission request signal to the accessory device, via the notification channel, in the asynchronous communication method.   
     
     
         27 . An imaging system including an imaging apparatus and an accessory device detachably mountable to the imaging apparatus,
 wherein the accessory device comprises:
 an accessory communication circuitry having, between itself and the imaging apparatus, a notification channel used for notification from the imaging apparatus to the accessory device, an accessory data communication channel used for data transmission from the accessory device to the imaging apparatus and an imaging apparatus data communication channel used for data transmission from the imaging apparatus to the accessory device; and 
 an accessory control circuitry configured to control the accessory communication circuitry, 
   wherein the imaging apparatus comprises:
 an imaging apparatus communication circuitry having, between itself and the accessory device, the notification channel, the accessory data communication channel and the imaging apparatus data communication channel; and 
 an imaging apparatus control circuitry configured to control the imaging apparatus communication circuitry.