| 摘要 |
1,158,482. Magnetic storage apparatus. WESTERN ELECTRIC CO. Inc. 9 Aug., 1966 [9 Aug., 1965], No. 35586/66. Heading H3B. A magnetic storage device includes a pair of conductive strips P, N which lie on the surface of a piece of magnetic material having two stable remanent states. The conductive strips are joined by conductors having two parallelconnected portions 15A, 15B each including a photo-responsive region PCA, PCB. A potential difference is applied between strips P, N and one or the other of the regions PCA, PCB is illuminated so that current flows through portion 15A or 15B. The magnetic material beneath the region enclosed by loop 15 is therefore switched to a downward or upward stable state depending on which photo-conductive region was illuminated. A further layer of remanent or low reluctance magnetic material is placed over the conductors to provide flux closure paths. The information stored is read out by directing plane polarized light at the storage region and monitoring either the transmitted or the reflected beam, the plane of polarization of which is rotated in a direction dependent upon the direction of the remanent flux. The lower magnetic film is made of an optically transparent material in both cases, while the upper layer is either transparent or reflective depending on the mode of read-out utilized. Yttrium aluminium garnet having a thickness of between one and three mils is suggested for both layers, or gadolinium iron garnet may be used. An yttrium aluminium garnet laser may be used both for writing and reading, the beam being directed through a digital light deflector. Instead of a loop 15, with connecting tabs 16, 17, separate straight portions each containing a photo-responsive region may be provided. In a storage array conductors P and N each consist of comb-like structures with the teeth of each comb connected together at each end, the two structures being positioned so that the teeth are interdigitated. Both random access and wordorganized arrangements are referred to. The magnetic layers may be deposited by sputtering and the conductors formed by photo-etching. The photo-responsive regions may be of photo-conductive material such as cadmium selenide or may consist of avalanching diodes. |
