Abstract: A semiconductor device may include a double hetero junction bipolar transistor and a field-effect transistor. The base of the bipolar transistor and the gate of the field-effect transistor are connected to each other to serve as an input terminal and the collector of the bipolar transistor and the drain of the field-effect transistor are connected to each other to serve as an output terminal. The bipolar transistor and the field-effect transistor may be created on a common substrate. In this case, both the bipolar and field-effect transistors can have the same multilayer/film structures.

Abstract: A method of testing a DC coupled optical receiver is provided. DC light is superimposed on an optical signal, the power of DC light is changed to observe waveform at a light extinction level, and the measurement and the prediction of the bit error rate are performed. Similarly, in a multi-channel DC coupled optical receiver, DC light is applied to a channel to be observed, while signal light is applied to other channels to observe cross-talk.

Abstract: An optical frequency division multiplexing network includes first optical communication paths connected to terminals, respectively, a second optical communication path connected to the outside and a node composed of a selection unit for selecting signals having optical frequencies to be sent to the plurality of terminals, respectively, from signals transmitted through the second optical communication path in optical frequency division multiplexing, a conversion unit for converting the selected signals into signals having a single optical frequency and an output unit for producing the converted signals to the terminals through the first optical communication paths, respectively.

Abstract: A parallel optical transmission device is disclosed, which comprises a transmitter section having one or a plurality of transmitter modules converting one or a plurality of input electric signals into optical signals; a section consisting of bundles of optical waveguides 20i, j transmitting the optical signals; and a receiver section having one or a plurality of receiver modules reproducing the electric signals from the optical signals thus transmitted to output them; wherein all propagation delay times from the input electric signals to the output electric signals are set in predetermined regions.

Abstract: A surface emitting semiconductor laser of a laminated structure having at least a light emitting active layer sandwiched between a dielectric film multi-layer mirror and a p-type semiconductor multi-layer mirror on a semiconductor substrate. The energy .DELTA.Ec of conduction band discontinuity is higher than the energy .DELTA.Ev of valence band discontinuity between at least two kinds of semiconductor layers with different refractive indices constituting the p-type semiconductor multi-layer mirror. On the other hand, the energy .DELTA.Ev of valence band discontinuity is higher than the energy .DELTA.Ec of conduction band discontinuity between at least two kinds of semiconductor layers with different refractive indices constituting the n-type semiconductor multi-layer mirror.

Abstract: An optical frequency division multiplexing network includes first optical communication paths connected to terminals, respectively, a second optical communication path connected to the outside and a node composed of a selection unit for selecting signals having optical frequencies to be sent to the plurality of terminals, respectively, from signals transmitted through the second optical communication path in optical frequency division multiplexing, a conversion unit for converting the selected signals into signals having a single optical frequency and an output unit for producing the converted signals to the terminals through the first optical communication paths, respectively.

Abstract: In a high speed logic circuit using a vertical hetero-junction bipolar transistor, in which two-dimensional carriers formed at a semiconductor hetero-junction interface are used as a base layer, the uppermost layer being a collector layer, the lowest layer being an emitter layer, two base electrodes making contact with the base layer are disposed so as to put a collector electrode, which is electrically in contact with the collector layer, therebetween. The base electrodes are used at the same time as a source electrode and a drain electrode, respectively, of a field effect transistor using the two-dimensional carriers as an active layer. The high speed logic circuit is so constructed that one of the base electrodes of the bipolar transistor is an input terminal; the other is connected with a power supply; the emitter is grounded; and the collector is an output terminal.

Abstract: An Al alloy extrusion material for the fuel-distributing pipe of automobile, consisting essentially of 0.3 to 1.0 wt. % of Si, 0.1 to 0.5 wt. % of Cu, 0.6 to 1.5 wt. % of Mg, 0.3 to 1.0 wt. % of Sn, 0.005 to 0.03 wt. % of Ti and the balance of Al and inevitable impurities and having uniformly dispersed Sn compounds with particle diameter of not more than 20 .mu.m and density of 20 to 700 grains/mm.sup.2 in the section perpendicular to the extrusion direction of material is disclosed, which is excellent in the chip separation property and the precision of cut face on cutting.

Abstract: An optical transmission time measuring device for an optical transmission path includes an optical bidirectional coupler having at least two input ports and at least two output ports. A pulse light source is connected to one of the input ports of the coupler and photodetector is connected to another one of the input ports. A timing control unit is used to time the pulse light source and the photodetector. A first optical connector is connected to one of the output ports for connecting a reference optical waveguide thereto and a second optical connector is connected to another one of the output ports for connecting a measured optical waveguide thereto.

Abstract: A connector is provided for connecting optic fibers to electrical circuit modules. The connector includes a plurality of fiber supporting means arrayed on a first surface of the connector base in a first direction. Supporting one end of a plurality of fiber sheets each comprised of a plurality of fibers bundled into a sheet form in such a manner that the sheet surface of each fiber sheet is substantially vertical to the first surface and the first direction. A plurality of opto-electrical circuits are connected to one sheet of the plurality of fiber sheets and each comprised of an electrooptical converter or an opto-electrical converter. A plurality of contact electrodes are also provided on a second surface, opposite to the first surface, of the connector base and connected to the plurality of optoelectrical circuits.

Abstract: A signal termination circuit comprising a resistor and a circuit network including two or more equivalent circuits connected in parallel to each other. The equivalent circuits respectively comprises resistors in the equivalent circuits, capacitors and inductances connected in series. The resistors have substantially the same resistive value.

Abstract: In a combination of sliding members which are suitable for use in the compressor for an automotive air conditioner, one of the members consists of an aluminum alloy which contains silicone particles consisting solely of eutectic silicon; and the other sliding member consists of a fluoride resin which contains carbon fibers and a calcium compound. The surface of the aluminum alloy can be finished to a desired smoothness as it does not contain any excessively hard substance. Also, since a calcium compound which is intermediate between carbon fibers and teflon resin in hardness is distributed in the teflon resin, the tendency of the carbon fibers to attack the aluminum alloy is reduced, and the aluminum alloy can achieve a sufficient wear resistance even though it does not contain any primary crystal silicon particles having a high hardness. Furthermore, the calcium compound serves as a lubricant, and reduces friction between the two sliding members.

Abstract: A two-way optical transmission system in which a plurality of light signals of wavelengths differing one from another are transmitted through a single optical fiber from one end thereof to the other end and from the other end to the one end. One or more assemblies each including an electrooptic transmitter, a dielectric thin-film filter and a rod lens and one or more assemblies each including a rod lens, a dielectric thin-film filter and an opto-electric receiver are connected to the single optical fiber at both ends thereof, respectively.

Abstract: In a network system wherein a plurality of terminal devices communicates with each other via respective node devices over a ring transmission line, a transmitting node device can confirm whether a multicast information transmission has succeeded or failed. The transmitting node device send a response frame after a multicast information frame. A receiving node device relays the multicast information frame and a response frame from the upstream node device to the downstream one when the multicast information has been received successfully, or in case of a failure in receiving the multicast information, sends a response frame to the downstream node device by changing at least part of the response frame from the upstream node device. The transmitting node device can determine from a received response frame if there is one or more of the receiving node devices which cannot receive the multicast information.

Abstract: In a memory array of memory cells each having at least a gate, a substrate, a source and a drain, a writing operation is effected when the substrate and the source and drain are at the same potential and when a potential difference V.sub.p exists between the potential of the substrate and the source and drain and that at the gate. The stored contents are erased when a potential difference V.sub.p exists between the gate and the substrate. The stored condition is prevented from changing when a potential difference V.sub.p exists between the substrate and the gate and when a potential difference V.sub.wd exists between the substrate and the source and drain. When such a memory array is partially erased, cells not to be erased are sequentially driven by applying a voltage V.sub.wd between the source and drain and the substrate of the cell, applying a voltage V.sub.p between the gate and the substrate of the cell, and applying the same potential to the substrate and the gate of the cell.

Abstract: A television receiver of electronic tuning type employing a variable capacitance diode in a local oscillator of its tuning circuit, which comprises a memory storing a plurality of digital data indicative of tuning voltages corresponding to a plurality of channels respectively so that a tuning voltage corresponding to a selected channel can be applied to the variable capacitance diode in the tuning circuit, a D/A converter converting a digital data corresponding to a selected channel into an analog voltage to be supplied to the variable capacitance diode, and a tuning voltage control circuit which functions to sequentially modify, at a predetermined rate, the digital data of the selected channel read out from the memory until the tuning point is reached in the tuning circuit, and which applies sequentially such a signal to the D/A converter, whereby the tuning circuit can be tuned to the selected channel regardless of secular and other variations in the operating characteristic of the variable capacitance diod