Dual-Channel Electromechanical Shutter Driver (ESD)
- Created on Tuesday, 01 April 2014
This device controls the electromechanical shutter in a digital or photographic camera.
This electronic device is designed to provide optimal control of an electromagnetically actuated shutter used on a digital or photographic camera. The SD36B1 Electromechanical Shutter Driver is designed to provide the drive pulses for opening and closing an electromagnetically actuated shutter. Electromechanical shutters are used when the exposure period for an electronic camera needs to be controlled outside of the range of electronic shuttering capabilities offered by the camera itself.
Commercial electromechanical shutters are available that claim to be able to operate continuously from 0 up to 5 Hz. However, the open/close response times and intervals vary significantly from unit to unit, and reliable operation can be extremely short-lived (even a matter of minutes).
The SD36B1 module produces two uniquely tailored drive pulses for opening and closing the leaves on a dual-coil, bistable type electromagnetic shutter. Commercial shutter driver modules only provide for a single set of characteristics for both the opening and closing drive pulse. The commercial shutter driver generates the same width and amplitude pulse (only the polarity is different) for both opening and closing the shutter. The opening and closing pulse must each be custom tailored for the specific shutter under use and for the specific shutter operation (opening or closing). As the shutter ages (from increased open/close cycles), the ability to custom-tailor the open and close pulse characteristics allows the in-service life of the shutter to be extended significantly. Shutters that were no longer usable with the standard commercial shutter driver module have obtained consistent and reliable open/close operation when driven via the SD36B1.
Internally, the SD36B1 uses two boards to perform all functions. The logic board performs all of the TTL (transistor–transistor logic) and sets the time duration of the output pulse. The driver board generates the actual output drive pulses that are sent to the shutter coils. Opto-isolators are also used on the input signals to eliminate any sensitivity to EMI (electromagnetic interference) noise.
This work was done by Garrett Clayo and Mark P. Wernet of Glenn Research Center.
Inquiries concerning rights for the commercial use of this invention should be addressed to NASA Glenn Research Center, Innovative Partnerships Office, Attn: Steven Fedor, Mail Stop 4–8, 21000 Brookpark Road, Cleveland, Ohio 44135. Refer to LEW-19052-1.