Camera data communication device

Claim 2

A camera data communication system for performing data communication operations (a) between a detachable external accessory and a camera body through a data communication line, and for performing data communication operations (b) between a camera data communication device and a circuit unit in the camera body through the data communication line, comprising: voltage level detecting means for generating a malfunction signal indicating a malfunction when the voltage level of the data communication line is abnormal, before a data communication operation (b) between said data communication device and said circuit unit through said data communication line is started; and control means for inhibiting data communication operations (a) and (b) through said data communication line in response to said malfunction signal.

Claim 3

A camera data communication system according to claim 1, further comprising warning means for warning a user in response to said malfunction signal.

Claim 4

A camera data communication system according to claim 1, further comprising release prohibition means for prohibiting a shutter release operation of said camera in response to said malfunction signal.

Claim 5

A camera data communication system according to claim 1, wherein said external accessory is an interchangeable lens.

Claim 6

A camera data communication system according to claim 1, wherein said voltage level detection means generates said malfunction signal when said data communication line is short circuited so that the voltage level thereof is grounded.

Claim 7

A camera data communication system according to claim 1, wherein said circuit unit is memory means capable of reading therefrom and writing thereto.

Claim 8

A camera data communication system for performing data communication operations (a) between a detachable external accessory and a camera body through a data communication line, and for performing data communication operations (b) between a camera data communication device and a circuit unit in the camera body through the data communication line, comprising: sequence control means for controlling the starting of a data communication operation (a) between said external accessory and said camera body through said data communication line after the completion of a data communication operation (b) between said camera data communication device and said circuit unit through said data communication line; voltage level detecting means for generating a malfunction signal indicating a malfunction when the voltage level of the data communication line is abnormal, before a data communication operation (b) between said data communication device and said circuit unit through said data communication line is started; and control means for inhibiting data communication operations (a) and (b) through said data communication line in response to said malfunction signal.

Claim 9

A camera data communication system for performing data communication operations (a) between a detachable external accessory and a camera body through a data communication line, and for performing data communication operations (b) between a camera data communication device and a circuit unit in the camera body through the data communication line, comprising: sequence control means for controlling the starting of a data communication operation (a) between said external accessory and said camera body through said data communication line after the completion of a data communication operation (b) between said camera data communication device and said circuit unit through said data communication line; voltage level detecting means for generating a malfunction signal indicating a malfunction when the voltage level of the data communication line is abnormal, before a data communication operation (b) between said data communication device and said circuit unit through said data communication line is started; and control means for inhibiting data communication operations (a) and (b) through said data communication line in response to said malfunction signal.

Claim 10

A data communication system for performing data communication operations between a detachable external accessory and a camera body, wherein said external accessory has a first data communication device, and said camera body has a second data communication device for performing data communication operations (a) with said first data communication device through a data communication line; a circuit unit separate from the detachable external accessory for performing data communication operations (b) with said second data communication device through said data communication line; voltage level detecting means for detecting the voltage level of said data communication line, before a data communication operation (b) between said circuit unit and said second data communication device through said data communication line is started, and for generating a malfunction signal indicating a malfunction when the detected voltage level of said data communication line is abnormal; and control means for inhibiting data communication operations (b) between said circuit unit and said second data communication device through said data communication line in response to said malfunction signal.

Claim 11

A data communication system for performing data communication operations between a detachable external accessory and a camera body, wherein said external accessory has a first data communication device, and said camera body has a second data communication device for performing data communication operations (a) with said first data communication device through a data communication line; a circuit unit separate from the detachable external accessory for performing data communication operations (b) with said second data communication device through said data communication line; voltage level detecting means for detecting the voltage level of said data communication line, before a data communication operation (b) between said circuit unit and said second data communication device through said data communication line is started, and for generating a malfunction signal indicating a malfunction when the detected voltage level of said data communication line is abnormal; and control means for inhibiting data communication operations (b) between said circuit unit and said second data communication device through said data communication line in response to said malfunction signal.

Claim 12

A camera data communication system for performing data communication operations between a detachable external accessory and a camera body through a data communication line, comprising: a circuit unit in the camera body for using the data communication line to perform a data communication to the system; voltage level detecting means for detecting whether a voltage level of the data communication line is normal or abnormal, before a data communication operation between the system and the circuit unit is started, and generating a malfunction signal indicating a malfunction if the voltage level is abnormal; and control means for inhibiting data communication operations to the circuit unit in response to the malfunction signal from the voltage level detecting means.

Claim 13

A camera data communication system for performing data communication operations between a detachable external accessory and a camera body through a data communication line, comprising: a circuit unit in the camera body for using the data communication line to perform a data communication to the system; voltage level detecting means for detecting whether a voltage level of the data communication line is normal or abnormal, before a data communication operation between the system and the circuit unit is started, and generating a malfunction signal indicating a malfunction if the voltage level is abnormal; and control means for inhibiting data communication operations to the circuit unit in response to the malfunction signal from the voltage level detecting means.

Claim 14

A camera data communication system according to claim 9, further comprising warning means for warning a user in response to the malfunction signal.

Claim 15

A camera data communication system according to claim 10, wherein the warning means includes indicating means for recognizably indicating a generation of malfunction in response to the malfunction signal.

Claim 16

A camera data communication system according to claim 11, wherein the indicating means includes an LCD for indicating.

Claim 17

A camera data communication system according to claim 9, further comprising release prohibition means for prohibiting a shutter release operation of the camera in response to the malfunction signal.

Claim 18

A camera data communication system according to claim 9, wherein the external accessory is an interchangeable lens.

Claim 19

A camera data communication system according to claim 9, wherein the external accessory is at least one of a speedlight, a data back, a personal computer and an electronic notebook.

Claim 20

A camera data communication system according to claim 9, wherein the voltage level detection means generates the malfunction signal when the data communication line is short circuited so that the voltage level thereof is grounded before a data communication operation between the system and the circuit unit is started.

Claim 21

A camera data communication system according to claim 9, wherein the circuit unit is memory means capable of reading therefrom and writing thereto.

Claim 22

A camera data communication system for performing data communication operations between a detachable external accessory and a camera body through a data communication line, comprising: a circuit unit in the camera body for using the data communication line to perform a data communication to the system; sequence control means for controlling the starting of a data communication operation between the system and the external accessory through the data communication line after the completion of a data communication operation between the system and the circuit unit through the data communication line; voltage level detecting means for generating a malfunction signal indicating detection of a malfunction when a voltage level of the data communication line is abnormal, before a data communication operation between the system and the circuit unit is started; and control means for inhibiting data communication operations between the system and the circuit unit in response to the malfunction signal from the voltage level detecting means.

Claim 23

A camera data communication system for performing data communication operations between a detachable external accessory and a camera body through a data communication line, comprising: a circuit unit in the camera body for using the data communication line to perform a data communication to the system; sequence control means for controlling the starting of a data communication operation between the system and the external accessory through the data communication line after the completion of a data communication operation between the system and the circuit unit through the data communication line; voltage level detecting means for generating a malfunction signal indicating detection of a malfunction when a voltage level of the data communication line is abnormal, before a data communication operation between the system and the circuit unit is started; and control means for inhibiting data communication operations between the system and the circuit unit in response to the malfunction signal from the voltage level detecting means.

Claim 24

A camera data communication system according to claim 18, further comprising warning means for warning a user in response to the malfunction signal.

Claim 25

A camera data communication system according to claim 19, wherein the warning means includes indicating means for recognizably indicating a generation of malfunction in response to the malfunction signal.

Claim 26

A camera data communication system according to claim 20, wherein the indicating means includes an LCD for indicating.

Claim 27

A camera data communication system according to claim 18, further comprising release prohibition means for prohibiting a shutter release operation of the camera in response to the malfunction signal.

Claim 28

A camera data communication system according to claim 18, wherein the external accessory is an interchangeable lens.

Claim 29

A camera data communication system according to claim 18, wherein the external accessory is at least one of a speedlight, a data back, a personal computer and an electronic notebook.

Claim 30

A camera data communication system according to claim 18, wherein the voltage level detection means generates the malfunction signal when the data communication line is short circuited so that the voltage level thereof is grounded before a data communication operation between the system and the circuit unit is started.

Claim 31

A camera data communication system according to claim 18, wherein the circuit unit is memory means capable of reading therefrom and writing thereto.

Claim 32

A camera data communication system for performing data communication operations between a detachable external accessory and a camera body through a data communication line, comprising: a first data communication device provided in one of the camera body and the external accessory; a second data communication device provided in the other of the camera body and the external accessory; at least one circuit unit provided in the other of the camera body and the external accessory, for communicating with the second communication devices voltage level detecting means provided in the other of the camera body and the external accessory, for detecting a voltage level of the data communication line before a communication operation between the second communication device and the circuit unit is started, and generating a malfunction signal indicating detection of a malfunction when a voltage level of the data communication line is abnormal; and control means provided in the other of the camera body and the external accessory, for inhibiting communication operations between the second communication device and the circuit unit in response to the malfunction signal from the voltage level detecting means.

Claim 33

A camera data communication system for performing data communication operations between a detachable external accessory and a camera body through a data communication line, comprising: a first data communication device provided in one of the camera body and the external accessory; a second data communication device provided in the other of the camera body and the external accessory; at least one circuit unit provided in the other of the camera body and the external accessory, for communicating with the second communication devices voltage level detecting means provided in the other of the camera body and the external accessory, for detecting a voltage level of the data communication line before a communication operation between the second communication device and the circuit unit is started, and generating a malfunction signal indicating detection of a malfunction when a voltage level of the data communication line is abnormal; and control means provided in the other of the camera body and the external accessory, for inhibiting communication operations between the second communication device and the circuit unit in response to the malfunction signal from the voltage level detecting means.

Claim 34

A camera data communication system according to claim 27, further comprising warning means for warning a user in response to the malfunction signal.

Claim 35

A camera data communication system according to claim 28, wherein the warning means includes indicating means for recognizably indicating a generation of malfunction in response to the malfunction signal.

Claim 36

A camera data communication system according to claim 29, wherein the indicating means includes an LCD for indicating.

Claim 37

A camera data communication system according to claim 27, further comprising release prohibition means for prohibiting a shutter release operation of the camera in response to the malfunction signal.

Claim 38

A camera data communication system according to claim 27, wherein the external accessory is an interchangeable lens.

Claim 39

A camera data communication system according to claim 27, wherein the external accessory is at least one of a speedlight, a data back, a personal computer and an electronic notebook.

Claim 40

A camera data communication system according to claim 27, wherein the voltage level detection means generates the malfunction signal when the data communication line is short circuited so that the voltage level thereof is grounded before a communication operation between the second communication device and the circuit unit is started.

Claim 41

A camera data communication system according to claim 27, wherein the circuit unit is memory means capable of reading therefrom and writing thereto.

Claim 42

A camera data communication method of performing data communication operations (a) between a detachable external accessory and a camera body through a data communication line, and of performing data communication operations (b) between a camera data communication device and a circuit unit in the camera body through the data communication line, comprising the steps of: detecting a voltage level of said data communication line before a data communication operation (b) between said data communication device and said circuit unit through said data communication line is started; generating a malfunction signal indicating a malfunction when the voltage level of the data communication line is abnormal; and inhibiting data communication operations (a) and (b) through said data communication line in response to said malfunction signal.

Claim 43

A camera data communication method of performing data communication operations (a) between a detachable external accessory and a camera body through a data communication line, and of performing data communication operations (b) between a camera data communication device and a circuit unit in the camera body through the data communication line, comprising the steps of: detecting a voltage level of said data communication line before a data communication operation (b) between said data communication device and said circuit unit through said data communication line is started; generating a malfunction signal indicating a malfunction when the voltage level of the data communication line is abnormal; and inhibiting data communication operations (a) and (b) through said data communication line in response to said malfunction signal.

Claim 44

A camera data communication method of performing data communication operations (a) between a detachable external accessory and a camera body through a data communication line, and of performing data communication operations (b), before the data communication operations (a), between a camera data communication device and a circuit unit in the camera body through the data communication line, comprising the steps of: detecting a voltage level of said data communication line before a data communication operation (b) between said data communication device and said circuit unit through said data communication line is started; generating a malfunction signal indicating a malfunction when the voltage level of the data communication line is abnormal; and inhibiting data communication operations (a) and (b) through said data communication line in response to said malfunction signal.

Claim 45

A camera data communication method of performing data communication operations (a) between a detachable external accessory and a camera body through a data communication line, and of performing data communication operations (b), before the data communication operations (a), between a camera data communication device and a circuit unit in the camera body through the data communication line, comprising the steps of: detecting a voltage level of said data communication line before a data communication operation (b) between said data communication device and said circuit unit through said data communication line is started; generating a malfunction signal indicating a malfunction when the voltage level of the data communication line is abnormal; and inhibiting data communication operations (a) and (b) through said data communication line in response to said malfunction signal.

Claim 46

A data communication method of performing data communication operations in a system including a detachable external accessory having a first data communication device, and a camera body having a second data communication device for performing data communication operations (a) with said first data communication device through a data communication line, and including a circuit unit separate from the external accessory for performing data communication operations (b) with said second data communication device through said data communication line, comprising the steps of: detecting a voltage level of said data communication line before a data communication operation (b) between said circuit unit and said second data communication device through said data communication line is started; generating a malfunction signal indicating a malfunction when the voltage level of the data communication line is abnormal; and inhibiting data communication operations (b) through said data communication line in response to said malfunction signal.

Claim 47

A data communication method of performing data communication operations in a system including a detachable external accessory having a first data communication device, and a camera body having a second data communication device for performing data communication operations (a) with said first data communication device through a data communication line, and including a circuit unit separate from the external accessory for performing data communication operations (b) with said second data communication device through said data communication line, comprising the steps of: detecting a voltage level of said data communication line before a data communication operation (b) between said circuit unit and said second data communication device through said data communication line is started; generating a malfunction signal indicating a malfunction when the voltage level of the data communication line is abnormal; and inhibiting data communication operations (b) through said data communication line in response to said malfunction signal.

Claim 48

A data communication method in a system wherein data communication operations are performed between a detachable accessory and a data communication device of a camera body through a data communication line, and wherein the camera body has a circuit unit using the data communication line for performing data communication operations with said data communication device, comprising the steps of: detecting a voltage level of said data communication line before a data communication operation between said circuit unit in said camera body and said data communication device through said data communication line is started, and generating a malfunction signal indicating a malfunction if the voltage level of the data communication line is abnormal; and inhibiting data communication operations of said circuit unit through said data communication line in response to said malfunction signal.

Claim 49

A data communication method in a system wherein data communication operations are performed between a detachable accessory and a data communication device of a camera body through a data communication line, and wherein the camera body has a circuit unit using the data communication line for performing data communication operations with said data communication device, comprising the steps of: detecting a voltage level of said data communication line before a data communication operation between said circuit unit in said camera body and said data communication device through said data communication line is started, and generating a malfunction signal indicating a malfunction if the voltage level of the data communication line is abnormal; and inhibiting data communication operations of said circuit unit through said data communication line in response to said malfunction signal.

Claim 50

A data communication method in a system wherein data communication operations are performed between a detachable accessory and a data communication device of a camera body through a data communication line, and wherein the camera body has a circuit unit using the data communication line for performing data communication operations with said data communication device, comprising the steps of: controlling the sequencing of data communication operations so that a data communication operation between said data communication device of said camera body and said external accessory through the data communication line is started after completion of a data communication operation between said data communication device of said camera body and said circuit unit through the data communication line; detecting a voltage of said data communication line before starting of a data communication operation between said data communication device of said camera body and said circuit unit through the data communication line; generating a malfunction signal indicating a malfunction when the voltage level of the data communication line is abnormal; and inhibiting data communication operations between said data communication device and said circuit unit through said data communication line in response to said malfunction signal.

Claim 51

A data communication method in a system wherein data communication operations are performed between a detachable accessory and a data communication device of a camera body through a data communication line, and wherein the camera body has a circuit unit using the data communication line for performing data communication operations with said data communication device, comprising the steps of: controlling the sequencing of data communication operations so that a data communication operation between said data communication device of said camera body and said external accessory through the data communication line is started after completion of a data communication operation between said data communication device of said camera body and said circuit unit through the data communication line; detecting a voltage of said data communication line before starting of a data communication operation between said data communication device of said camera body and said circuit unit through the data communication line; generating a malfunction signal indicating a malfunction when the voltage level of the data communication line is abnormal; and inhibiting data communication operations between said data communication device and said circuit unit through said data communication line in response to said malfunction signal.

Claim 52

A camera data communication system for performing data communication operations between a detachable external accessory and a camera body through a data communication line, comprising: a first data communication device provided in one of the camera body and the external accessory; a second data communication device provided in the other of the camera body and the external accessory; at least one circuit unit provided in the other of the camera body and the external accessory, for communicating with the second communication device; a detecting circuit provided in the other of the camera body and the external accessory, for detecting a voltage level of the data communication line before a communication operation between the second communication device and the circuit unit is started, and generating a malfunction signal indicating detection of a malfunction when a voltage level of the data communication line is abnormal; and a control circuit provided in the other of the camera body and the external accessory, for inhibiting communication operations between the second communication device and the circuit unit in response to the malfunction signal from the voltage level detecting device.

Claim 53

A camera data communication system for performing data communication operations between a detachable external accessory and a camera body through a data communication line, comprising: a first data communication device provided in one of the camera body and the external accessory; a second data communication device provided in the other of the camera body and the external accessory; at least one circuit unit provided in the other of the camera body and the external accessory, for communicating with the second communication device; a detecting circuit provided in the other of the camera body and the external accessory, for detecting a voltage level of the data communication line before a communication operation between the second communication device and the circuit unit is started, and generating a malfunction signal indicating detection of a malfunction when a voltage level of the data communication line is abnormal; and a control circuit provided in the other of the camera body and the external accessory, for inhibiting communication operations between the second communication device and the circuit unit in response to the malfunction signal from the voltage level detecting device.

Claim 54

A camera data communication system for performing data communication operations (a) between a detachable external accessory and a camera body through a data communication line, and for performing data communication operations (b) between a camera data communication device and a circuit unit in the camera body through the data communication line, comprising: a voltage level detector which generates a malfunction signal indicating a malfunction when the voltage level of the data communication line is abnormal, before a data communication operation (b) between said data communication device and said circuit unit through said data communication line is started; and a controller which inhibits data communication operations (a) and (b) through said data communication line in response to said malfunction signal.

Claim 55

A camera data communication system for performing data communication operations (a) between a detachable external accessory and a camera body through a data communication line, and for performing data communication operations (b) between a camera data communication device and a circuit unit in the camera body through the data communication line, comprising: a voltage level detector which generates a malfunction signal indicating a malfunction when the voltage level of the data communication line is abnormal, before a data communication operation (b) between said data communication device and said circuit unit through said data communication line is started; and a controller which inhibits data communication operations (a) and (b) through said data communication line in response to said malfunction signal.

Claim 56

A camera data communication system for performing data communication operations (a) between a detachable external accessory and a camera body through a data communication line, and for performing data communication operations (b) between a camera data communication device and a circuit unit in the camera body through the data communication line, comprising: a sequence controller which controls the starting of a data communication operation (a) between said external accessory and said camera body through said data communication line after the completion of a data communication operation (b) between said camera data communication device and said circuit unit through said data communication line; a voltage level detector which generates a malfunction signal indicating a malfunction when the voltage level of the data communication line is abnormal, before a data communication operation (b) between said data communication device and said circuit unit through said data communication line is started; and a controller which inhibits data communication operations (a) and (b) through said data communication line in response to said malfunction signal.

Claim 57

A camera data communication system for performing data communication operations (a) between a detachable external accessory and a camera body through a data communication line, and for performing data communication operations (b) between a camera data communication device and a circuit unit in the camera body through the data communication line, comprising: a sequence controller which controls the starting of a data communication operation (a) between said external accessory and said camera body through said data communication line after the completion of a data communication operation (b) between said camera data communication device and said circuit unit through said data communication line; a voltage level detector which generates a malfunction signal indicating a malfunction when the voltage level of the data communication line is abnormal, before a data communication operation (b) between said data communication device and said circuit unit through said data communication line is started; and a controller which inhibits data communication operations (a) and (b) through said data communication line in response to said malfunction signal.

Claim 58

A data communication system for performing data communication operations between a detachable external accessory and a camera body, wherein said external accessory has a first data communication device, and said camera body has a second data communication device for performing data communication operations (a) with said first data communication device through a data communication line; a circuit unit separate from the detachable external accessory for performing data communication operations (b) with said second data communication device through said data communication line; a voltage level detector which detects the voltage level of said data communication line, before a data communication operation (b) between said circuit unit and said second data communication device through said data communication line is started, and generates a malfunction signal indicating a malfunction when the detected voltage level of said data communication line is abnormal; and a controller which inhibits data communication operations (b) between said circuit unit and said second data communication device through said data communication line in response to said malfunction signal.

Claim 59

A data communication system for performing data communication operations between a detachable external accessory and a camera body, wherein said external accessory has a first data communication device, and said camera body has a second data communication device for performing data communication operations (a) with said first data communication device through a data communication line; a circuit unit separate from the detachable external accessory for performing data communication operations (b) with said second data communication device through said data communication line; a voltage level detector which detects the voltage level of said data communication line, before a data communication operation (b) between said circuit unit and said second data communication device through said data communication line is started, and generates a malfunction signal indicating a malfunction when the detected voltage level of said data communication line is abnormal; and a controller which inhibits data communication operations (b) between said circuit unit and said second data communication device through said data communication line in response to said malfunction signal.

Claim 60

A camera data communication system for performing data communication operations between a detachable external accessory and a camera body through a data communication line, comprising: a circuit unit in the camera body for using the data communication line to perform a data communication to the system; a voltage level detector which detects whether a voltage level of the data communication line is normal or abnormal, before a data communication operation between the system and the circuit unit is started, and generates a malfunction signal indicating a malfunction if the voltage level is abnormal; and a controller which inhibits data communication operations to the circuit unit in response to the malfunction signal from the voltage level detector.

Claim 61

A camera data communication system for performing data communication operations between a detachable external accessory and a camera body through a data communication line, comprising: a circuit unit in the camera body for using the data communication line to perform a data communication to the system; a voltage level detector which detects whether a voltage level of the data communication line is normal or abnormal, before a data communication operation between the system and the circuit unit is started, and generates a malfunction signal indicating a malfunction if the voltage level is abnormal; and a controller which inhibits data communication operations to the circuit unit in response to the malfunction signal from the voltage level detector.

Claim 62

A camera data communication system for performing data communication operations between a detachable external accessory and a camera body through a data communication line, comprising: a circuit unit in the camera body for using the data communication line to perform a data communication to the system; a sequence controller which controls the starting of a data communication operation between the system and the external accessory through the data communication line after the completion of a data communication operation between the system and the circuit unit through the data communication line; a voltage level detector which generates a malfunction signal indicating detection of a malfunction when a voltage level of the data communication line is abnormal, before a data communication operation between the system and the circuit unit is started; and a controller which inhibits data communication operations between the system and the circuit unit in response to the malfunction signal from the voltage level detector.

Claim 63

A camera data communication system for performing data communication operations between a detachable external accessory and a camera body through a data communication line, comprising: a circuit unit in the camera body for using the data communication line to perform a data communication to the system; a sequence controller which controls the starting of a data communication operation between the system and the external accessory through the data communication line after the completion of a data communication operation between the system and the circuit unit through the data communication line; a voltage level detector which generates a malfunction signal indicating detection of a malfunction when a voltage level of the data communication line is abnormal, before a data communication operation between the system and the circuit unit is started; and a controller which inhibits data communication operations between the system and the circuit unit in response to the malfunction signal from the voltage level detector.

Claim 64

A camera data communication system for performing data communication operations between a detachable external accessory and a camera body through a data communication line, comprising: a first data communication device provided in one of the camera body and the external accessory; a second data communication device provided in the other of the camera body and the external accessory; at least one circuit unit provided in the other of the camera body and the external accessory, for communicating with the second data communication device; a voltage level detector provided in the other of the camera body and the external accessory, which detects a voltage level of the data communication line before a communication operation between the second data communication device and the circuit unit is started, and generates a malfunction signal indicating detection of a malfunction when a voltage level of the data communication line is abnormal; and a controller provided in the other of the camera body and the external accessory, which inhibits communication operations between the second data communication device and the circuit unit in response to the malfunction signal from the voltage level detector.

Claim 65

A camera data communication system for performing data communication operations between a detachable external accessory and a camera body through a data communication line, comprising: a first data communication device provided in one of the camera body and the external accessory; a second data communication device provided in the other of the camera body and the external accessory; at least one circuit unit provided in the other of the camera body and the external accessory, for communicating with the second data communication device; a voltage level detector provided in the other of the camera body and the external accessory, which detects a voltage level of the data communication line before a communication operation between the second data communication device and the circuit unit is started, and generates a malfunction signal indicating detection of a malfunction when a voltage level of the data communication line is abnormal; and a controller provided in the other of the camera body and the external accessory, which inhibits communication operations between the second data communication device and the circuit unit in response to the malfunction signal from the voltage level detector.