Abstract: A paper transport system used in connection with a thermal analog recorder is provided. This system engages the paper for a predetermined length of time and subsequently releases it employing mechanical means. Roller means are provided for engaging and transporting a heat sensitive paper. When the test paper is inserted into the nip formed between the roller means, a tapered resistor element residing on at least one of the rollers is made to develop a non-uniform temperature profile when energized from the output of a test source which permanently marks or records on the test paper. An improved method of single channel thermal analog recording is also disclosed employing this device.

Abstract: An analog chart recorder is provided having a heater assembly which includes a tapered, electrically resistive element that develops a non-uniform temperature profile on electrical energization along its length. A substrate is provided under the resistive film which is in thermal contact with the film. A heat sink in thermal contact with the substrate provides that the temperature distribution will achieve steady state. Means are provided for advancing a heat sensitive medium past and in contact with the heater assembly thus providing the analog chart recorder.

Abstract: A shift register that utilizes a plurality of amorphous semiconductor threshold switches. The shift register is driven by a two phase clock with odd-numbered threshold switches being supplied a pulse waveform of one phase and even-numbered threshold switches being supplied a pulse waveform of a different phase. The threshold switches have a V-I characteristic that is strongly temperature dependent and each is heated by a heating element which can take the form of an amorphous semiconductor current controlled negative differential resistance device, with the current controlled negative differential resistance devices and the threshold switches fabricated simultaneously on a common substrate.

Abstract: An erasable optical memory array having at each storage location a non-crystalline, semiconductor threshold switching device. The threshold voltage of each switching device is strongly temperature dependent and each switching device has a finite recovery time when switched to its low resistance state. Means are provided for periodically sampling each of the switching devices with voltage pulses repetitive at a first frequency and having a first voltage level sufficient to switch to the low resistance state only those switching devices heated above room temperature by a thermal image. Additional means are provided to sample the switching devices at a second frequency greater than the first frequency and at a voltage level less than that of the first voltage level to maintain the switched devices in the low resistance state upon removal of the thermal image.

Abstract: A switching device having as the active switching element a material with a band gap between 0.6 and 1.2 eV and a mean coordination number of 4. These parameters provide a material having a glass transition temperature that is relatively high such that the material is resistant to devitrification. Amorphous (a-) CdAs.sub.2 is the most promising active switching material having the parameters, and a method of making thin films of a-CdAs.sub.2 by open source evaporation is disclosed.

Abstract: A method of making thin film devices with selective etchants. Specifically, a fabrication process in accordance with the invention provides for the manufacture of amorphous chalcogenide sandwich structures. Such structures consist of a glass substrate, a chromium or aluminum electrode on the substrate bounding one side of the chalcogenide layer, and a second electrode of aluminum bounding the other side of the chalcogenide layer. First, the aluminum electrode is etched without affecting the other layers. Secondly, the chalcogenide layer is etched with a solution which attacks only the chalcogenide material and neither the overlying aluminum nor the underlying chromium or aluminum electrode. This two-step process is particularly suitable for fabricating current controlled negative differential resistance devices which requires the precise registration of one of the electrodes with the boundary of the chalcogenide such that a coextensive boundary is achieved.

Abstract: A thermal printer comprised of a shift register, a line buffer and a plurality of printheads in heat-transfer relationship with a heat-sensitive record medium. The shift register and line buffer are comprised of a plurality of stages or modules with each module having an amorphous semiconductor heating element that exhibits current controlled negative differential resistance in heat-transfer proximity to a heat-gated amorphous semiconductor threshold switch which has a V-I characteristic which is strongly temperature dependent. The printheads are comprised of the amorphous semiconductor heating elements. Data is stored in the shift register by means of a video data signal and two oppositely phased clock signals of an amplitude that will only bias a heated threshold switch to conduction, with transfer of data to the line buffer being achieved in a parallel format by a third properly phased clock signal.