IEEE TRANSACTIONS ON MAGNETICS, VOL. 50, NO. 11, NOVEMBER 2014 3101804 Development of a Permanent Magnet as Magnetizer for Linear Magnetic Pattern Manufacturing Heng-Sheng Hsiao 1 , Zhi-Hao Xu 1 , Tsung-Shune Chin 2 , Cheng-Kuo Sung 1 , Sheng-Ching Wang 3 , and Jen-Yuan (James) Chang 1 1 National Tsing Hua University, Hsinchu 30013, Taiwan 2 Feng Chia University, Taichung 40742, Taiwan 3 National United University, Miaoli 36003, Taiwan An energy saving permanent magnet type magnetizer is proposed, examined, and validated in this paper for the manufacturing of linear pattered magnetic medium for the precision control application. With the ultimate goal placed on providing sufficient magnetic field to overwrite and modify patterns on the magnetic media, parameter studies are conducted through finite element studies with results validated by magnetic flux density distribution measurements from produced incremental and index point patterns. Feasibility of utilizing the patterned medium for positioning control is validated through repeatability measurements, indicating that the proposed magnetizer can produce magnetic patterns rendering adequate magnetic signal strength and repeatability in linear precision control applications. Index Terms— Magnetic circuit, magnetization, patterned media, permanent magnet. I. I NTRODUCTION L INEAR position sensing system has been widely used for position control in engineering products, such as guide rail units for macroprecision applications or pick-and-place robots for microprecision applications. Two types of linear sensing systems are commonly found in engineering products, namely optical and magnetic sensing systems, respectively. Even though its precision is not as accurate and resolution is not as high as an optical sensing system, a magnetic sensing system on the other hand offer more compact, quicker response, better resistance to unclean environment, such as dust, debris, humid, oil, and so on, all of which are desirable and offer more economical alternative for industry precision applications [1]. Although the optical sensing systems use light as the source, whereas the magnetic sensing systems adopt magnetic signals, these systems both employ binary code, of which code is generated by sensing incremental segments or polarized patterns on media (either optical or magnetic), to precision moving components with respect to preferred reference datum. In manufacturing the patterned magnetic media, electromagnet as the source for magnetization has been widely used in the industry. In the past few decades, [2], [3] focus on the mentioned magnetizer has been placed in optimizing its geometric designs for optimized magnetic strength. Motivated by drawbacks of electromagnetic magnetizer, such as high electric power consumption, impulse shock under magnetizing, and high cost for maintaining charger connected to electromagnet, the research presented in this paper focuses on developing a proof-of-concept magnetizer using permanent magnet for magnetizing patterned magnetic media for preci- sion control. This paper will first aim on designing the magne- Manuscript received March 7, 2014; revised May 16, 2014; accepted June 10, 2014. Date of current version November 18, 2014. Corresponding author: J.-Y. Chang (e-mail: jychang@pme.nthu.edu.tw). Color versions of one or more of the figures in this paper are available online at http://ieeexplore.ieee.org. Digital Object Identifier 10.1109/TMAG.2014.2331250 tizer which is consisted of a permanent magnet connected to a C-shaped iron yoke. Strength and distribution of magnetic field produced by the magnetizer will then be examined through finite element numerical studies, which will be confirmed by calibrated experiments. The patterned magnetic media will be produced by the magnetizer, of which functionality is later confirmed by experimental repeatability measurements. II. MAGNETIC CIRCUIT AND MECHATRONIC SYSTEM DESIGN In [4], it was found that most magnetizing platforms utilize electromagnet as the magnetizing source. The magnetizer commonly consists of an iron yoke over the coils which are attached to an actuator for positioning control. The coils are then connected to a charger for applying different magnitude and directions of current during magnetization process. Appar- ently, in practical practice, the charger requires a large amount of electricity to transfer into magnetic field. Due to global rising awareness of energy saving and requirements for safety during manufacturing, a different type of magnetizer made of permanent magnet instead of electromagnet is proposed in this paper. In developing the permanent magnetizer for patterned media, being able to reach the media material’s saturation point when the media is subjected to the magnetizer’s magnetic flux is of critical importance. To avoid creating unexpected patterns, being able to manage magnetic flux leakage between the magnetizer and the magnetic media within desirable oper- ating surface area of the media is also the key engineering parameter in this paper. To exercise the aforementioned design parameters, in this paper, as shown in the schematic illus- tration as depicted in Fig. 1, a magnetic circuit structure is constructed in which the magnetizer is composed of a rare- earth permanent magnet assembled on a C-shaped yoke, the fixture. The dimension of the scheme is normalized with respect to width direction of magnetic media. The concept of designing a C-shaped yoke is to form a closed magnetic 0018-9464 © 2014 IEEE. Personal use is permitted, but republication/redistribution requires IEEE permission. See http://www.ieee.org/publications_standards/publications/rights/index.html for more information.