Design of a voice coil motor used in the focusing system of a digital video camera

Yu, Hsing–Cheng; Lee, Tzung-Yuan; Wang, Shyh-Jier; Lai, M.-L.; Ju, Jau-Jiu; Huang, Der‐Ray; Lin, Shir‐Kuan

doi:10.1109/tmag.2005.855161

Cited by 45 publications

(2 citation statements)

References 4 publications

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“…2 From the perspective of lens designer, such miniaturized cameras have been traditionally made with a voice coil motor to move the lens barrel and provide a variable image distance for the camera. 3 These cameras are inherently bulky, and in their basic design, they share the same focusing mechanism as their bigger counterparts that are used in, for instance, digital single lens reflex cameras. Thus, in order to decrease the size and power consumption and increase focusing speed of small cameras, liquid microlens alternatives have been proposed in the past decade with proven commercial success in niche applications like intra-oral cameras.…”

Section: Introductionmentioning

confidence: 99%

Tunable microlens actuated via a thermoelectrically driven liquid heat engine

Ashtiani

Jiang

2014

Journal of Applied Physics

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We have developed a thermally actuated liquid microlens. An embedded thermoelectric element is used to actuate the liquid based heat engine. A closed-loop system is harnessed to drive and stabilize the temperature of the heat engine. Direct contact between the thermoelectric device and the water results in greatly improved, sub-second thermal rise time (0.8 s). The water based heat engine reacts to the variation in the temperature via expansion and contraction. In turn, the shape of a pinned water-oil meniscus at a lens aperture is deformed in response to the net volume change in the water, creating a tunable microlens. A method to fabricate microfluidic devices with relatively high thickness (250-750 lm) and large length-to-depth aspect ratio (280:1) was developed and used in the process. After fabrication and thermal calibration, optical characteristic of the microlens was assessed. Back focal length of the microlens was shown to vary continuously from À19.6 mm to À6.5 mm as the temperature increased from 5 C to 35 C. A thin film air was further introduced to insulate the heat engine from the substrate to protect the microlens area from the temperature fluctuation of the heat engine, thus preventing the change of the refractive indices and thermally induced aberrations. Wavefront aberration measurement was conducted. Surface profile of the microlens was mapped and found to have a conical shape. Both 3-dimensional and 1-dimensional thermal models for the device structure were developed and thermal simulation of the device was performed. V

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Section: Introductionmentioning

confidence: 99%

Tunable microlens actuated via a thermoelectrically driven liquid heat engine

Ashtiani

Jiang

2014

Journal of Applied Physics

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“…Recently, a voice coil motor ͑VCM͒ has been used in the autofocusing ͑AF͒ system of a commercial digital camera to meet the trend of miniaturization. 1 Some works [2][3][4][5] proposed the design methods for the VCM, while Yu et al 1 developed the adaptive model following control ͑AMFC͒ to overcome the loading variation due to the posture change of a camera. However, the AF system must also operate well under handshaking, which was not taken into account in the work.…”

Section: Introductionmentioning

confidence: 99%

Design and implementation of antihandshaking position control for a voice coil motor

Lin

Wang

Wang³

2008

Journal of Applied Physics

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This paper deals with the position control of the voice coil motor ͑VCM͒ with handshaking. A disturbance observer is proposed to estimate the low-frequency handshaking disturbance, so that a handshaking-robust controller can be constructed. While a handshaking stabilizer can compensate for the vibration of the whole lens set, a robust controller is still required to precisely hold the autofocusing lens by rejecting the handshaking disturbance. To meet the request of miniaturization, the control is implemented on a field programmable gate array chip.

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Auto-focusing actuator and camera module including flexible diaphragm for mobile phone camera and wireless capsule endoscope

Song

Nam²,

Kim³

et al. 2009

Microsyst Technol

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Recent cellular phones have high-resolution, compact digital camera modules that have several millions of pixels. Although being small, such several mega-pixel camera modules definitely need to be able to execute autofocusing and/or optical zooming in order to obtain precise images. Hence, image photographing devices having driving mechanisms that can move a lens group in the direction parallel to an optical axis have appeared such as piezoelectric type, linier motor type, and voice coil motor type. Although these technologies are already popular in existing digital cameras, driving mechanism for camera modules in cellular phones needs to be extremely improved because their requirements are totally different from usual digital cameras. Compact image photographing devices, which are installed in mobile apparatuses, should improve portability by reducing their sizes and weights and increase use-time of a battery by reducing power consumption. Weakened suspension (e.g. thickness is 0.02 mm or less) in order to minimize an elastic coefficient for drastic decrease of driving current frequently occurs permanent step-out of a lens group by plastic deformation of the metal suspensions when it comes to getting shocks from accidental drops of a handset. The proposed auto-focusing actuator using conductive polyimide as a flexible diaphragm satisfies these requirements of ultra slim cell phones. This polyimide suspension shows ultimate toughness when it comes to drop-test of cell phones. This actuator also shows high performance quite enough for several mega-pixel camera modules for ultra slim cellular phones; the moving range is up to 0.35 mm, the DC sensitivity is 0.2 mm/140 mA, and the resistance at the terminal is 22 Ohm, whereas the aperture is 6.8 mm, and the overall size is 10 9 10 9 3.95 mm. Most of all, the robustness against drop and shock has been dramatically increased, with no change of reliability under high temperature and high humidity condition, because of the flexibility of the conductive polyimide suspension.

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Design of a voice coil motor used in the focusing system of a digital video camera

Cited by 45 publications

References 4 publications

Tunable microlens actuated via a thermoelectrically driven liquid heat engine

Tunable microlens actuated via a thermoelectrically driven liquid heat engine

Design and implementation of antihandshaking position control for a voice coil motor

Auto-focusing actuator and camera module including flexible diaphragm for mobile phone camera and wireless capsule endoscope

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