Contactless Power Supply for Layer Layer-Selection Selection-Type Recordable Multi Multi-Layer Optical Disk

Using mtary transformers, oontactless power is supplied to the drive mechanism of a LayerSelwhn-Qpe Recordable Multi-Layer Optical Disk. The prntntypc! tmmmits ~uE6cic!nt, P~&C pmer tn a mt~tjng disk. 1. M e n The LayerSelectio~rType Recordable U-Rl Multi-Layer Optical Dlsk is one of the best post-Blu-ray Disc tehmlog~es that wdl have a capacity of up to a terabyte per disk [I, 21. Ths optical dLsk needs electrical power to change the optid reflectivity of an electm chromic layer for layer selection We developed a contactless mechanism that can supply electrical power h m the dnve base to the rotational body and the M. We showed that a pe tsansmitted electsical power to a mtabng disk and changed the optical reflectivity of an LS-R Multi-Layer Optical Disk without wy contmthg mechamm 2. ~ O f ~ ~ P o w e r s u p p ~ m l s h ows our design of a power supply system for an IS-R Multihyer O p t i d D~sk. This system has two special features. One is a contachs power supply mthat transmits power h m an irrotational to a rotational body The purpose is to supply stable elechic power with sdkient ~liability. Another feature is a muhchannel voltage generator, whlch supplies voltage to each layer of a disk through a multi-pin comxtor. The purpose is to minimize the number of power channels between a drive base and a hub. In thls study we investigated the hst featw, a new Power supply mechanism. Table 1 shows target spdcations of the power supply mechamm. These electrical spe&mtiom WPSC! m m l d hy a previous =port, of an LC-R Multi-hyer @tical Disk [S]. The mechanical speulication should mahtmn mechanical compatbility between a new drive and former dnves so as to use the same form hetor of an o p t d h k . We investgated the mechanical structure of mnventional DVD dnves ancl mncluded that the diameter of a hub d10ulcl be within 30 mm to keep the same smke of an optical pickup. Table 2 shows a amparison of power supply designs from an imtational to a rotational body Rotary transformer^ are widely used to transmit power and slgnaLs to the rotary head of a 0-7803-9494-1/06/$20.00©2006 IEEE MP31 16:00 – 18:30 video tape reoorder, so such products have already proven the ~ h b i l i t y of mtary transformers. The power of an electric generator is pmportional to the mtation speed of the hub, so the generating power is unstable when the rotation speed is varied. The contacting mechanism uses a conductive bearing or a conductive shaff edge. However, these produce unstable contachng ~sistance bmuse the contacting area is gradually d m & during disk rotation due to the surface oxidation The~fore, a contactless mechanism with rotary transformers is the best solution Figure 2 shows the equivalent circuit of a contactless power supply mechanism. A 100 KHz AC power source V, is added to the rotary transformer of the stator side and a voltage Vnd is i n d u d in the rotary tramformer of the rotor side. The bridge diode generates a rectified voltage V&&, which is added to the load of each layer of the dkk. 3. Retfillts of Prototype Figure 3 shows a cornparkan between a previous prototype 111 and our prototype. The previous prototype consisb of 6 array conductive ball bearings. Each bearing forms a conductive path to each layer The pmblems with this mechanism a R that it has an unstable contacting resistance and q u i m increased space for the multiple ball bearings. Our prototype can solve these problems. The voltage a t each layer is stable because the resistance of the transformers is stable during disk rotation The size of the transformers can be the same even if the number of layers is increased because they use a multichannel voltage generator We obtained the following mults and satisfied the target specifications described in Table 1. (1) Voltage of the rotatingdisk: max 5 [V] O Current of the rotating disk: max 5 [d (3) Rotating sped of the disk: 0 6000 [rpml (4) Diameter of t,he hub: 30 [mml The thickness of this mechanism is within 41.2 mm, which meets the mechanical standard of a desktop personal computer. 4. Conclusion Using rotary transformers, we developed a contactless power supply mechanism for a Layerselection-Qpe Recordable Multi-Layer Optical Disk. This method provides stable resistance during disk rotation and requires minimum space for the power supply mechani-m Our prototype transmitted sficient electrical power to the rotating disk and confmned the feasibility of a contactless power supply 5. Referem 111 K Kojima and M. Rrao, "Investigation into Reconling on Electmhromic Information Layers of MultiInformation-Layer Optical DL-k Using Electrical Layer Selection" Jpn J. Appl. Phys. Vol. 43, No. 10 (20041, pp. 7058. 121 A. Himtsune, M. Mukoh, and M. Terao, "LayerSelection-me Recordable Optical Disk with Inorganic ElechochromicFilm, " Jpn J. Appl. Phys. Vol. 45 No. 2 B (2006), pp. 1235. 131 M. Mukoh A Hirotme, T. Maetla, and M. Terao, "LayerSe1ectiodl)pe Recolrlable Optical Dkk with Inorganic Electsochromic DoubleDecker S t r u c t w " F'mmlhgof PCOS 2005, pp. 70. Irrotational Body Rotational M y I I . . I Multi-Channel Multi-Pin supply Voltage Connector Generator I I Mechanism I \ ~ r i h e Base ~ \ u b LS-R* Multi-Layer Optical Disk * LS-R: Layer-Seledion-Type Recordable Fig. 1 Power Supply System for LS-R* Multi-Layer Optical Disk Table 1 Target Specifications of Power Supply Mechanism Table 2 Comparison of Power Supply Designs Item SpecIfkathn Voltage [V] 2 5 Electrical Load Resistance ! Layer @cL4] 1 C m t / Layer [m A] 2 5 P o w / Layer [m W] 4-25 Mechanical Diamctw of Hub [mm] --30 Concept Candidate Main Problem Rnnklng contaotlcas Rotary T r a n s f o ~ ~ Hish Mechanism Electric Generator Unstable Generating Power LOW cm~tin8 Conductive Bearing Low Unstable Contacting Resistance Low Rotary Transformer Rotary Transformer I Fig. 2 Equivalent Circuit of Contactless Power Supply Mechanism / I Controlling Contaoting Power Swply ! Circuit Using 6 Array Ball b r i n g I ' :,,,,,,,,,,,,,,,,,,------------------I : (a) Previous Prototype I I Multi-Channel Voltage Generator ! I / I