The wireless remote control apparatus used for home electronic appliances generally uses infrared rays having a wave length on the order of 900 to 950 nm. A transmitter of the remote control apparatus transmits a signal which has been modulated at about 40 kHz with a code to be transmitted. On the other hand, a receiver detects the signal to demodulate it for eliminating the 40 kHz component in the carrier to obtain data (refer to a brochure "Countermeasure for preventing malfunction of infrared remotely controlled home appliances" published by a Foundation Kaden Seihin Kyokai, July, 1987).
In general, the wireless remote control apparatus for a camera intermittently emits infrared light as is done similarly with an electronic flash to increase an effective range of the infrared light having flash intervals representative of transmission data unlike the modulation system of the remote control for home appliances.
However, remote control apparatus using a modulation system for home electronic appliances requires a modulation circuit for modulating a signal with a transmission code and a demodulating circuit for demodulating the modulated code for transmitter and receiver, respectively. These circuits are complicated and large in size, so that they are very cumbersome for a compact camera having a restricted component installation area and cost.
On the other hand, since flash type of remote control apparatus which is used for remotely controlling the camera includes a transmission circuit similar to an electronic flash circuit, the circuit components are large in size and scale. Accordingly, it is hard to adopt such a flash type of remote control apparatus for a camera in which a camera body and a remote control unit are integral with each other during normal picture taking and the remote control unit is removed from the camera body for taking a picture using the remote control. Since the flash interval represents transmission data in this flash type remote control, complicated codes can not be transmitted. In addition the camera sometimes malfunctions on exposure to light from other electronic flash and a fluorescent lamp, for example.
Furthermore both types of remote control have a common problem that a receiver circuit consumes power on standby while waiting for a signal from a transmitter, which power is the the same as that consumed on reception of a transmitted signal. Even during normal picture taking mode, the remote control circuit continues to operate, resulting in wasteful consumption of power. This will be a cause of premature depletion of batteries in a system which uses batteries.
USPTO Backgrounds
USPTO Backgrounds