Anti Shake : Sony

Anti-Shake

The DYNAX underwent a number of changes over the years and was eventually transformed into a digital SLR with the introduction of the DYNAX 7D. A major feature of the 7D was an anti-shake function, which represented a major technology advance for the DYNAX SLR series and is regarded as one of the most important benefits of the change from film to digital technology. It enabled photographers to significantly enlarge their images without the problem of blur and to print them out using personal inkjet printers.

The DYNAX design engineers were guided by a philosophy that insisted the anti-shake system should be available for use with any lens, should be available without photographers needing to replace their existing lenses, and should be offered at an affordable price. So virtually from the beginning it was decided to incorporate the anti-shake technology into the body of the camera.

The biggest technical challenge this decision posed was designing a new mechanism to drive the CCD (the image sensor) smoothly and speedily. Using a micro-motor or other actuators would inevitably cause the CCD to shake back and forth and rattle diagonally, as it moved to compensate for the shaking of the camera.

Yet even the slightest amount of judder was unacceptable, given that the CCD is used to directly record the image being shot.

(1) Weight (2) Piezoelectric Element (3) Driveshaft

So the engineers set about developing an entirely new mechanism to manipulate the CCD. The result was the Smooth Impact Drive Mechanism or SIDM, a supersonic linear actuator that takes advantage of a piezoelectric element and friction caused by the movement of the CCD.

The CCD is placed on the SIDM's driveshaft, which is connected to the end of the piezoelectric element. When a voltage is applied to the element, it takes on the characteristics of supersonic elasticity.

To visualize how the SIDM mechanism works, imagine an object placed on a flat board. If the board is moved from side to side gently, the object moves with the board because of friction. But if the board is moved from side to side at great speed, the object will remain motionless in the same position, due to the law of inertia. This is the concept behind the SIDM mechanism and why the CCD is able to move without juddering.

As noted, the driveshaft is connected to the end of the piezoelectric element, which slowly extends or contracts, then returns to its original size rapidly, a series of movements that is repeated over and over. The CCD plate is closely but not rigidly attached to the driveshaft, and so moves with it.

Because the plate is free to slide with the movement of the shaft, the attached CCD experiences no rattle or shake. Unlike the movement produced by a motor, then, the CCD can freely slide at varying speeds from low to high without judder.

In the DYNAX 7D and the DYNAX 5D two angular velocity sensors were used to detect shake in both the vertical and horizontal directions. A dedicated chip to process the amount of shake data was also included. As well as utilizing information regarding the type of lens attached and distance of the subject, both cameras could use the sensors' data (as processed by the dedicated chip) to drive the SIDM both horizontally and vertically. This resulted in anti-shake compensation being made at virtually the same time the shaking occurs. In particular, the engineers designed the anti-shake function to be built into the camera body, so that all types of camera users could take successful photos without having to purchase new lenses to overcome camera shake.

ART en EU 2008 10 DYNAX Anti-Shake

ART en EU 2008 10 DYNAX Anti-Shake

Anti-Shake

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