Miniature Motorized Lens Focusing

Motorizedlens motion and new image sensor technology are combining to unleash the fullimaging potential of high-resolution, miniature security cameras and biometric detectionsystems. New M3-F focus modules from NewsScale Technologies add motorized focus to multi-function, high-resolutioncameras. The technology increases the accuracy and versatility of mobiledevices, without adding weight or bulk, and also operates from battery power.

Adding dynamic focus enables bothwide field and macro imaging, enabling multifunction cameras to image facialfeatures, capture video, read barcodes and scan fingerprints with a singledevice. Optical zoom provides greater clarity of details for a higher level of accuracyand security. Auto focus provides faster and more accurate matches in biometricdetection applications such as facial recognition and iris scanning.

"This complete micro motion system includesthe piezo motor, a drive IC, position sensor, magnet and a microcontroller. Thesystem only needs I²C or SPI position commands and power input tocommand the system to specific positions, and offers one half micron positioningresolution," says David Simpson, vice president of marketing and sales at NewScale Technologies.

"What's unique is that we areenabling our customers to introduce additional functions and features intoproducts using a module that is basically complete. The user selects a sensoror ISP, as well as an appropriate lens (from M6 to M12), to transform systemsthat were traditionally fixed focus by adding motorized focus and zoomcapabilities," he says.

New Scale Technologies' piezo technology, includinginnovations in the piezo plates and miniature drive circuitry, significantlyreduces the size and improves the performance of micro motion systems. But nowthey are also providing building blocks that simplify system development.

"Our flagship tool is the SQL-1.8 SQUIGGLEmotor, but we have found that customers have been challenged with the nuancesof integrating the piezo motor with the drive circuitry and position sensor,"says Simpson, "so we decided, in addition to providing base level componentsfor small motion systems, to introduce the M3-F module (micro mechatronic focusmodule)."

The M3-F focus modules are customizable,fully integrated, closed-loop actuators that mount directly on a PCB-mounted camera.The modules offer compact size (20 x 22 x 16 mm), resolution 0.5 I.25m, accuracybetter than 30 I.25m and step and settle times that are < 20 ms for a 30 I.25mstep.

The M3-F module is built on New Scale's M3design platform, incorporating a piezoelectric SQUIGGLE micro motor, motor driveASIC, position sensor and microprocessor. The modules accept high-level digitalcommands via standard serial interface (I2C or SPI). No external control boardis necessary. M3-F modules have low power consumption and maintain focusposition during power-off, and use a 3.3V input for battery-powered operation.

The M3-F modules have smaller size, higherresolution, and lower power use than traditional stepper motors. They are lessexpensive, afford more flexibility and are easier to integrate than liquidlenses. They accept many off-the-shelf lenses typically used in fixed-focusapplications and can be rapidly customized to OEM specifications includingmounting interface, lens dimensions, and macro and infinity image planelocations.

"A keypart of the timing of this product is that the pace of innovation with imagesensors is accelerating to the point that resolution and image quality isincreasing much faster than the optical components and motion systems requiredfor focus," says Dan Viggiano, director of custom products at New Scale. "Whatwe recognized is the customer need to very quickly adapt to the new imagesensors and the higher quality that is available. In partnership with opticalcompanies, we're making sure that the latest lens systems available to themarket and matched up with these image sensors are directly compatible with asmall motion system."

The motion system provides a closed-loopcontrol that is ready to accept a lens and can be mounted on top of the imagesensor. It can immediately be used as a focusing module to improve imagequality and expand the range over which the imaging system operates. This isapplicable to multi-purpose cameras, as well as machine vision applications,where there is a need to focus over various ranges based on assemblyrequirements or the parts the system is imaging.

Applied in the biometric andsecurity camera areas, the solution also provides a low-power solution and theability to "mobilize" devices by making them small, lightweight and able to runfrom batteries. But what has happened is that customers were looking for asolution where existing systems that required three cameras could instead beoptimized to use only one.

"Many systems with multiple cameras are bulky,but by integrating our modules with some of the highest resolution imagesensors available today offering 10 or 12 megapixel resolution, they can usethe module to focus very closely and capture enough detail to image an iris,change focus to image a bar code on the back of a license, and change focus tozoom the camera and capture video," says Viggiano.

Viggiano says that systems thatmight require three cameras, or three sets of fixed optics, can potentially becombined into one. Some customers are integrating all of those capabilitiesinto one, and others are integrating individual pieces. But it is all based onneeding the highest resolution and how to mobilize applications and put theminto the hands of security personnel and locations that can be moved quicklyand easily.