Browsing by Author "Ju, JJ"

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A novel dual focus objective lens for DVD/CD pick-up head
(1998-03-01)
Liu, PY
;
Shieh, HPD
;
Ju, JJ
;
Tsai, ST
;
Yang, TM
A new dual focus objective lens of combinig aspherical surfaces of DVD and CD for DVD/CD pick-up head was designed. Numerical analysis based on the diffraction model were studied to trade off the spot size, side lobe, and energy ratio of DVD and CD, The hybrid aspherical surfaces of DVD and CD are optimized for low aberration. The spot size of full wave half maximum (FWHM) are 0.553 and 0.88 mu m for DVD and CD, respectively, measured from thus constructed double rings lens.
An automatic pin identification method for a three-phase DC brushless motor
(2005-10-01)
Wang, SJ
;
Cheng, CC
;
Lin, SK
;
Ju, JJ
;
Huang, DR
The pin identification is to find the definition of each connecting pin of a three-phase brushless motor. The 11 pins of the motor can be distinguished into three groups by a simple resistance measurement method. An automatic method has two steps. In the first step, the motor is in an open-circuited mode; and the individual pins of the windings are identified by comparing back electromotive forces. A special integral is defined and used to match Hall signal pins with the Hall sensors. The polarity of each pair of the Hall signal pins is determined by the second step of a standstill method. The proposed method is illustrated and verified by an experiment.
Design of a voice coil motor used in the focusing system of a digital video camera
(2005-10-01)
Yu, HC
;
Lee, TY
;
Wang, SJ
;
Lai, ML
;
Ju, JJ
This paper raises a valid method to design a voice coil motor (VCM) used in the focusing system of a digital video camera (DVC). A better VCM performance, such as lower battery consumption, higher efficiency, and shorter focusing time, can be achieved by turning the diameter of a winding coil, the thickness of the magnet, and the winding spaces in a VCM.
Low power consumption focusing actuator for a mini video camera
(2006-04-15)
Yu, HC
;
Lee, TY
;
Lin, SK
;
Kuo, LT
;
Wang, SJ
A novel low power consumption autofocusing actuator in a mini video camera is constructed in accordance with the result of a systematic design procedure of voice coil motors (VCM). This paper emphasizes the position control of such a VCM. The position feedback signals are provided by a magnetoresistive (MR) encoder. The position estimation algorithm (PEA) is developed to precisely decode the MR signals for the position of the moving part of the VCM. Different postures change the loading of the moving part of the VCM, so that an adaptive model-following control system based on the PEA is proposed to compensate for the loading variation. The experiments verify the fast dynamic performance and high power efficiency of the VCM. (C) 2006 American Institute of Physics.