| 摘要 |
1283542 Data storage ENERGY CONVERSION DEVICES Inc 15 Aug 1969 [22 Aug 1968 15 Jan 1969] 40918/69 Headings H3B and H3T [Also in Division G4] Data is stored on a layer of a semi-conductor material which is reversibly switchable between two stable states by the application of energy, one of the states being such that the material has a generally disordered, amorphous atomic structure with localized bonding and the other state having a more ordered, crystalline structure, the material having detectable characteristics, e.g. electrical resistance, which vary between the two states whereby the stored data may be retrieved. Two types of memory material are described, reference being made to Specifications 1,070,411 and 1,070,412. In the first type the application of energy above a threshold value to a selected area of the material causes an abrupt change in the resistance of the material, which, in the two stable states is respectively 10<SP>6</SP> and 10<SP>2</SP> ohms. In the second type application of energy above a threshold value causes a more gradual change in resistance to a value depending on the value of the incident energy used. The energy used in basically heat which may be generated by a number of methods, e.g. using electron beams, laser beams, photoflash lamps, voltage or current electrodes, or a heated air jet. In an embodiment, Fig. 1, a current electrode 12 is supplied with voltage pulses 16 and is "scanned" across the surface of the material to store data at selected discrete areas. The resistance of the material is changed from 10<SP>6</SP> ohms to 10<SP>2</SP> ohms by a current pulse of duration about 1 millisecond and amplitude 5 milliamps. The reverse change is initiated by a pulse of duration 2 microseconds and amplitude 100 milliamps. In a further embodiment, Fig. 9 (not shown), the latter type of store is used as an electrostatic printer. Numerous embodiments are briefly described each depending on a change in a particular property of the semi-conductor as it is changed between its two stable states. The data may be retrieved utilizing the fact that the dielectric properties, the refractive index, capacitance, charge retention, surface reflectance, light absorption, light transmission, and particle scattering properties of the semi-conductor are different in the two states of the material. |
