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Volume 52 (Feb 09, 2006)
NEC Electronics' motor driver ICs for lens control in today's most talked-about digital movie cameras (1/2)
Motor driver ICs and the evolution of digital movie cameras
Digital movie cameras integrate digital camera and movie functions, and make it possible to enjoy movies anytime and anywhere—all from the convenience of a digital camera. And thanks to the use of a memory card as a recording medium, there is no need for a driving mechanism in the recording part, thus making it possible to achieve a high level of reliability and compactness. Digital movie cameras are capable of capturing 5.0-megapixel still images while simultaneously shooting moving images, and continue to evolve both in terms of ease of use and image quality.
Although a driving mechanism is no longer necessary within the recording part, motor driving is needed for focus, zoom and other functions. It is the job of the driver IC to use voltage and electric current to rotate the motor after receiving control signals from the microcontroller.
Motors controlled by motor driver ICs include stepping motors used for focus motor driving, DC motors used for zoom motor driving and spindle motors used for disk rotation (Figure 1). NEC Electronics offers a vast array of motor driver ICs suitable for use in the driving of these and other motors.
Digital movie cameras and motor driver IC performance
Silence is highly desired when it comes to motor driving in digital movie cameras. Since images and sound are simultaneously recorded during the filming of moving images, even the sound of the zoom (motor driving sound), which isn't a concern when using a digital camera, ends up being recorded as noise. To make motor driving even quieter, current waveforms must be made smoother. To this end, motor driver ICs employ what is referred to as the "micro step driving method." With this method, the difference in the value of the current that flows between the adjoining magnetic poles is converted in incremental steps, thus enabling rotation of the stepping motor in small steps. The micro step driving method, which has already evolved from 64 steps to 128 steps, has significantly contributed to making motor driving quieter than ever before.
In line with the trend toward smaller, thinner and lighter digital movie cameras, demand is increasing for motor driver ICs to not only perform better, but also to be smaller and thinner. Since sales of digital movie cameras are easily swayed by design, it is imperative that motor driver ICs be made smaller and thinner to increase design flexibility.
Features of NEC Electronics' motor driver ICs
NEC Electronics offers a complete lineup of motor driver ICs that are ideal for reducing noise, size, thickness and weight in digital movie cameras (Figure 2). Take, for example, the µPD168117AFC-BA2. This stepping motor driver IC enables 128 steps via pulse input, thus making motor driving with little noise or vibration possible. In addition, use of the MOS process reduces power dissipation and voltage loss during the output stage to a degree beyond what is possible with conventional drivers that employ bipolar transistors. This 7-channel H-bridge driver also enables simultaneous driving of two stepping motors, two DC motors and a coil. Furthermore, both package area and height can be reduced thanks to the use of a 64-pin FLGA package (6 mm x 6 mm).
Compliance with the latest technologies
Amidst the debut of new high-performance products on the market and ever-shortening product life cycles, NEC Electronics has received high acclaim from users for quickly adopting micro step control of 128 divisions and providing customers with high-level technologies that not only meet customer needs, but are also reasonably priced. The package itself has gone from a 48-pin TQFP (9 mm x 9 mm) to a 64-pin FPLGA (6 mm x 6 mm), and its thickness has been reduced from 1.2 mm to 0.75 mm, thus making sets thinner and more compact. In these and other ways, NEC Electronics continues to strive to be among the first in the industry to make technological innovations that meet the needs of today's digital movie cameras.
So what do users have to say about our motor driver ICs? To find out, we spoke with Kazuhiko Sugimoto (Personal Electronics Group, DI Company, DI Technical Designing Unit, General Manager) of Sanyo Electric Co., Ltd. about how his unit employed NEC Electronics' motor driver ICs in the development of the Xacti VPC-C5 digital movie camera.
The reliability that comes with products from NEC ElectronicsNEC Electronics' outstanding technological capabilities and sincere approach to customer satisfactionUnited efforts between users and vendors
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