Abstract: An inscribable record carrier (1) is described, which comprises a previously recorded servo-track structure provided with a recording layer. The contrast between the servo-tracks (3) provided with information areas and the intermediate tracks (5) is increased by combining wide tracks (20) with a white-writing recording layer (24) or by combining narrow servo-tracks (20) with a black-writing recording layer (21). (FIGS.

Abstract: On the semiconductor body of a MOSFET (1), the semiconductor body of a thyristor (5) (or of a bipolar transistor) is located for thermal conduction purposes. The anode and cathode terminals (A, K) (emitter and collector terminal) are connected to the gate terminal (G) and to the source terminal (S) of the MOSFET (1), respectively. The thyristor (bipolar transistor) is rated so that it turns on before a temperature of 150.degree. to 180.degree. is obtained which is critical for the MOSFET. Thus the gate-source capacitance of the MOSFET is effectively shortcircuited and the MOSFET turns off.

Abstract: An optical record carrier having an information recording track which is inscribed with control data indicative of the change in average level of read-out signals from recorded and unrecorded portions of the track. Read apparatus for such record carrier scans the track with a radiation beam and derives a read-out electrical signal therefrom. The apparatus includes a signal-processing circuit which is adjusted for operation at the average level of signals derived from recorded portions of the track, such average level being determined by a programmable control unit from the recorded control data and the measured average level of signals from unrecorded portions of the track. Tracking of the scanning beam is also controlled in conformity with the difference in average signal strength from recorded and unrecorded portions of the track.

Abstract: A method and device are disclosed for recording information represented by a code signal Vd on an optically readable record carrier (1) by means of optically detectable recording marks (8). Outside the areas (30) of the record carrier (1) which are used for recording the information signal reference marks (33) are formed. When the record carrier is read a detection signal Vd is generated, from which the code signal is derived by comparison of the detection signal Vd with a decision level Vref. The decision level Vref is derived from those portions (34) of the detection signal Vd which are representative of the reference marks (33).

Abstract: Holder has two opposed holding elements (5) with holding means (6) for holding a disc at its circumferential edge inside the holder. At least one holding element (5) can be moved out of a holding position by means of an adjusting element (4) to receive or to release the disc. The movable holding element is adjustable to at least two holding positions in order to hold discs of substantially different diameter.

Abstract: A cassette contains an information disc arranged to be rotatable in the space inside the cassette and has an opening in a main wall of the housing to provide access to the disc surface for a pick-up. In order to minimize the area of the opening, while maintaining a wide field of use for the cassette, the opening is arranged asymmetrically relative to a radius of the disc.

Abstract: An optical scanning apparatus, which includes a radiation source (7) supplying a scaning beam (b.sub.1), an objective system (8) for focusing the scanning beam (b.sub.1) to a scanning spot (S.sub.1) in an information plane (2) to be scanned, and a first diffraction element (9) for deforming the beam reflected by the informatin plane (2) in such a way that a focus-error signal can be derived therefrom. The apparatus also includes a second diffraction element (10) for forming two auxiliary beams (b.sub.2, b.sub.3) by means of which a tracking-error signal can be derived, which second diffraction element has such a size and is arranged at such position that the beams originating from the first diffraction element (9) do not traverse the second diffraction element.

Abstract: Supporting elements (10) arranged between the frame and the sub-frame (1) for damp vibrations or shocks exerted on the sub-frame via the frame. The sub-frame (1) carries part including a turn-table (3) and a pivotal scanning arm (4) with a scanning element (6). The supporting elements (10) are connected to the sub-frame (1) by means of pivotal joint (20), the pivotal axis (21) of said pivotal joints (20) extending radially or substantially radially of the moss center (M) of the sub-frame (1) including the parts carried by this sub-frame.

Abstract: The color sensor system has at least three electronic light transmitters each emitting light of a determined narrow-band range of wavelengths, which under the control of a transmission control device in the course of a control cycle, illuminate successively the colored surface of the object in question for a brief period of time with light pulses of a predetermined intensity. The light reflected in each case from the colored surface upon the arrival of the light pulses is received by an electronic light receiver and converted into electrical signals. The electrical signals that are emitted successively by the light receiver in the course of a control cycle are conducted to an evaluation device for a color determination.

Abstract: A mold is manufactured using a substrate and hub also used in the manufacture of the disc. A structure carrier provided with a mold structure is detachably connected to a substrate, and the mold structure is then centered relative to the central recess of an auxiliary tool. A disc hub is then centered relative to the recess and fixed to the substrate and the assembly of the hub, the substrate, and the structure carrier is centered on a mold base which likewise has a central recess. The structure carrier is fixed to the base, and the substrate is detached from the structure carrier leaving the mold structure centered relative to the central recess.

Abstract: Information carrier includes an optically readable disc with a center hole and a hub with radially resilient clamping members which extend through the center hole to retain it on the disc and center it with respect to the information carrying surface on the disc. The hub further carries a sleeve which centers it on a spindle, and a magnetizable clamping ring for retaining it on a turntable, which carries permanent magnets. In an information carrier having two discs sandwiched together, the clamping members of each hub extend between the clamping members of the other hub and pass through the center holes of both discs to engage the opposite disc and retain the discs to each other.

Abstract: A new gas distributor 31 provides an extremely uniform gas across a wide cross section distance. An OMVPE reactor equipped with this distributor, a unique low volume quartz insert, a load-locked growth chamber and a low pressure operation scheme provide a reactor system capable of growing extremely uniform GaAs and AlGaAs epilayers across four two-inch wafers or one three to four inch wafer with atomic layer abruptness capablity. The performance of such an OMVPE reactor provides superior morphology and throughout compared to conventional OMVPE reactors with equivalent performance to MBE. Since the gas distributor is capable of distributing an extremely uniform gas across a wide cross-section distance, it can also be employed in other types of OMVPE reactors to improve the material uniformity.

Abstract: A method for separating laser diodes. The diodes are monolithically produced from a semiconductor substrate wafer which through an epitaxy process has been provided with a layer sequence suitable for laser operation. First, the semiconductor substrate wafer is covered with a first mask which defines the interspaces between the mirrors of adjacent laser diodes. Then the mirror surfaces are etched out of the semiconductor substrate wafer. Thereafter, the wafer is covered with a second mask for defining separation trench areas between the mirror surfaces of adjacent laser diodes and for protecting the remaining wafer parts. Then, separation are etched into the trench area. Finally, the laser diodes are separated by breaking the wafer along the trenches. In a preferred embodiment, the wafer thickness is at most twice the distance between the mirror surfaces of adjacent laser diodes and the trench depth is at least one fourth of the wafer thickness.

Abstract: With a light waveguide feedthrough for optoelectronic modules a light waveguide fiber (1) is guided hermetically tight and mechanically stable, in particular long-term stable, directly through a module housing wall. The light waveguide fiber (1) is compression glazed in the housing-side front portion of a relatively thick-walled metal tubule (2) without external coating (5) and affixed by adhesion in its rear portion. An application of the light waveguide feedthrough according to the invention is in optoelectronic transducer modules.

Abstract: A circuit technique is presented for mixing current mode logic and emitter coupled logic in a manner which reduces active and passive component counts for performing recognized logic functions. The reduced counts permit greater circuit density while reducing power consumption in comparison to conventional emitter coupled logic circuitry. The mixing is also provided in a way for making all imputs and outputs compatible with conventional emitter coupled logic levels. Various logic circuits are illustrated to demonstrate the versatility of the technique. For example, a transparent high D-latch (FIG. 2), a D flip-flop with true output (FIG. 4), a two-to-one multiplex latch (FIG. 6), and other D flip-flops having set and reset inputs (FIG. 7), multiplex data inputs (FIG. 8), and Exclusive OR data inputs (FIG. 9) are circuits wherein the inventive technique is employed to advantage.

Abstract: For floating zone drawing of semiconductor rods having diameters greater than 100 mm, at the beginning of the zone drawing process, in particular during melting on of the seed crystal to the semiconductor rod to be drawn, a high load change and impedance change occurs. The power from the high-frequency (HF) generator is no longer coupled thereto optimally. Heating up the feed line to the induction heating coil is the result. This heating is avoided by connecting the HF generator via a feed line to a tank circuit device. A variable tank circuit capacitor connected in parallel and to the series oscillator circuit coil feeding one side of a parallel circuit of a heating circuit capacitor and the induction heating coil. The variable oscillator circuit capacitor is adjusted as a function of the voltage drop across the induction heating coil.

Abstract: An optoelectronic coupling arrangement for a light waveguide cable (3), at each of whose ends an optoelectronic transmitter and/or receiver structural unit (1, 2) are optically coupled to, permit a signal or data transmission to or from an arbitrarily rotatable electronic system. The light waveguide cable (3) is flexible, but torsionally-stable or not rotated, and connected at its one end with the one optoelectronic transmitter and/or receiver structural element (1). The light waveguide cable (3) is separated at its other end into two axially opposing members which are each fastened in their lateral portions of a pivot bearing (4) and, consequently, are coupled axially rotatable optically and mechanically with each other. The lateral portion of the pivot bearing (4) associated with the end member of the light waveguide cable (3) is rigidly connected with a carrier (6) rotatable about an axis of rotation (5) on which the other optoelectronic transmitter and/or receiver structural unit (2) is fastened.

Abstract: Amplifiers operating in push-pull are implemented to obviate input baluns and output signal combiners and their attendant losses. Amplifiers having two signal branches that each receive the input signal and have their signal branch outputs connected directly together. Each branch operates during alternate half cycles of the input signal while direct combining of the branch signal outputs produces a composite signal corresponding to the complete input signal. Each branch includes a matching input circuit and a heterojunction bipolar transistor whcih may be configured in either common collector or common emitter arrangement. The transistors are different since one is an NPN while the other is a PNP but they are selected to have similar direct current and radio frequency characteristics.

Abstract: Improved series and shunt switching cells for selectively switching an RF input signal to an output over a wide range of frequencies and in a linear manner. The series cell includes an input FET which has the source electrode clamped by means of a diode clamping circuit. The diode clamping circuit is in series with a second FET which has applied to the gate electrode a control voltage. A third FET has its source electrode connected to the source electrode of the second FET and has the drain electrode coupled through a diode to the drain electrode of the second FET. The drain electrode of the third FET is coupled to the gate electrode of a fourth FET where the source electrode of the fourth FET controls a series switching FET to enable the input signal to be switched to the output.

Abstract: The invention involves a method for the monolithic fabrication of front face optoelectronic couplers and/or optical components (10) including a ridge structured waveguide (4) in which the light-coupling edges (2) of the component (10) using a mask in the desired structure are etched out of a wafer (1) of suitable material. With this method not only the light-coupling edges (2) of the component (10) but also the ridge waveguides (4) are readily fabricated in monolithic technology. To this end, the invention provides that the etched grooves (3) forming the light-coupling edges (2) with their side walls are covered with a first layer (5) of organic material which subsequently is removed outside the groove (3) so that the remaining residue at least nearly fills the etched groove (3), and that subsequently over the first a second layer (6) of organic material is applied which after appropriate treatment is used as etching mask for etching the predetermined ridge waveguide structure (4) out of the wafer (1).