Abstract: There is disclosed a communications terminal, including a video telephone, for transmitting and receiving video and audio. The terminal includes video recording apparatus and video reproduction apparatus with the video recording apparatus being switchable into an "off" mode by operation of a flap. In order to use the transmission capacity of the communications terminal even when the flap is closed, an image which already exists in a video memory is transmitted. A changeover is automatically made to the video memory by operation of the flap.

Abstract: In digital, magnetic and optical storage systems for audio/video/data, a Viterbi detector is extended by a control output, and a PLL is controlled by a variable delay line at the output or inside of the PLL.

Abstract: A videophone system having an electronically controlled shutter to vary the amount of light falling onto the target by a shutter, e.g., for a greater or lesser length of time during a short exposure time rather than b y means of a controlled mechanical aperture. Data reduction is used for the transmitted signal, a control circuit is used for the exposure time, and the mains power supply, which produces ambient light, are coupled by means of a PLL circuit so that the exposure time occurs at the same phase of the mains voltage. In this way, interference occurring when data reduction is used for the signal to be transmitted is avoided and macroblocks are not formed when no difference signal is present.

Abstract: A method for the production of picture sequences for a fast search operation in a film play-back device (10, 40) is proposed. In this case, the video data of the individual pictures of the film are stored in digitally coded form in a storage unit (11, 41). The method is distinguished by the fact that 1. the video data of the pictures are read out from the storage unit (11, 41) at an increased speed, that 2. the read-out video data are decoded at an increased speed in a decoder (18, 43), that 3. only the video data of specific individual pictures are selected from the decoded video data and are fed to an encoder (21, 45) which operates at a regular speed.

Abstract: The invention relates to a method for recording longitudinal track bundles on an information medium. The method involves recording tracking information in special tracks in said track bundles. The special tracks are contiguous between each other. When recording a new track bundle a recording and/or reading head may be positioned using tracking information contained in special tracks of a previously recorded track bundle. Several examples of patterns used for coding tracking information in the special tracks we described.

Abstract: A reproducing and/or recording device for reproducing, or for recording on, an optical recording medium, having a tracking sychronization circuit (1), which has a variable center frequency generator (12, 13). The tracking synchronization circuit (1) can be operated with different center frequencies depending on application, and this has the advantage that identically designed tracking synchronization circuits (1) can be used for different purposes. It is advantageous that adaptive adjustment of a center frequency once prescribed is additionally possible during operation, thus increasing the capture range of the tracking synchronization circuit.

Abstract: The invention relates to a method and a device for producing a scanning device, also termed a pick-up, for optical recording media, which can be produced with a low outlay and thus cost-effectively, and in comparative terms has a low tilt of the objective lens and improved guidance properties. According to the invention, during the connection of an objective lens holder and actuator base plate, a prestress is applied to wires provided as elastic support of the objective lens holder on an actuator base plate. Scanning devices produced according to the invention for optical recording media have a low tilt of the objective lens and improved guidance properties.

Abstract: Electronic circuit having a digital controller operation of a synchronous motor.Precision motors for driving, for example, a video head drum in video recorders are normally designed as externally commutated synchronous motors. These motors are driven with square-wave voltages by a digital controller (CON), whose circuitry can easily be implemented.The object of the present invention is to specify an electronic circuit of the type mentioned initially for controlling a synchronous motor, which enables good synchronism and the motor to be operated with little electrical noise.This object is achieved in that the synchronous motor is driven by sinusoidal signals, a separate control signal from the controller (CON) influencing the amplitudes of the drive signals (U1, V1, W1). A regulating signal for regulating the synchronous motor is produced by a sensor (GE) which is arranged on the synchronous motor, which regulating signal produces a fixed phase relationship between rotor revolution and drive signals.

Abstract: In order to produce synchronous control signals of a video recorder, in particular of a digital video recorder, a position pulse of the scanner motor, which coincides with the beginning of the video frame, is used as time zero point. Time markers in which changes in the control signals take place are calculated starting from this time zero point. These time markers and the bit patterns occurring at these time markers are stored as data words in a data field and, for corresponding time markers, the corresponding data word is output in parallel, that is to say synchronously. A realization is possible by means of a microcontroller and a controllable output memory, the microcontroller containing the functions of capture register, timer, calculation unit and comparator.

Abstract: For the transmission of additional data on a television channel the lines of the vertical blanking interval are used. It is intented to improve program information by so-called electronic program guides, which are based on the transmission of a large database. For these EPGs the additional data shall be broadcasted within the teletext data stream in a compatible manner. The EPG data are splitted into two data streams, wherein the transmitted data are organized in data blocks. Data blocks from different streams may interrupt each other. According to the invention the data pages (A, B) are stored sequentially in two different buffers (PA, PB) and processed alternatively. The blocks of the pages transmitted in the first stream are stored in a first block buffer (BB1) and the blocks of the pages transmitted in the second stream are stored in a second block buffer (BB2).

Abstract: A control unit, stores addresses of a write pointer of a buffer in the case of the last valid subcode information and starts with a synchronization byte following an interruption. The synchronization byte is provided for the synchronization of the data stream in the buffer, an item of address information which identifies the interruption location in the data stream, the starting point of the synchronization being formed by a valid subcode, the address information being used as a reference both for the location of the interruption on the information medium and for the last valid data in the buffer and the writing in the buffer. This is done so that uninterrupted reproduction of information is provided despite vibrations in the playback device.

Abstract: A device for reading from or writing to an optical recording medium is disclosed which has at least two information carrier layers spaced apart from one another, as well as a light source, an optical unit and a detection unit. The device permits a plurality of information carrier layers to be read from and/or written to simultaneously using light of a single wavelength. A partial beam generating element emits two polarized beams which differ in terms of polarization direction and propagation behaviour.

Abstract: A device for reproducing a stereoscopic image viewable within an increased observation area, the device including an image display device which displays a plurality of images of an object pixel by pixel from various perspectives, a polarization arrangement for producing a first polarized image associated with a right eye and a second polarized image associated with a left eye of an observer, a lens network spaced directly after the polarization arrangement which directs beams associated with each of the left and right polarized images to the respective left and right eye for representing the object pixel by pixel for observing the stereoscopic image, wherein the lens network and polarization arrangement are arranged such that the stereoscopic image can be perceived in a first region of the observation area without polarized spectacles, and in a second region outside the first region of the observation area, by means of polarized spectacles over the left and right eyes.

Abstract: A line deflection circuit for a television receiver or a switched-mode power supply operate with a switching transistor that is connected in series with the primary winding of a transformer and is periodically switched on and off by a switching voltage. In such a circuit, appreciable turn-on and turn-off losses, which reduce the overall efficiency of the circuit, are produced at the switching transistor, particularly at higher operating frequencies. Within a control circuit a DC voltage source is connected to the base of the switching transistor via a periodically actuated switch element and a coil having a core and a tap. The two parts of the coil are wound in opposite senses, and the tap is connected via a diode to ground or to the emitter of the switching transistor.

Abstract: A cassette drive mechanism for cassettes wherein cassettes can be played back which have different sizes and for which different tape drive systems are otherwise required. By placing the different cassettes into a common cassette receiving device, the adaptation of the drive and tape scanning systems is automatically carried out at the side of the drive mechanism.

Abstract: Method and apparatus for recording a digital signal wherein the recording rate is higher than the available data rate. In such a situation, the available excess recording capability is used for extending the playing time by the existing storage capacity of a magnetic tape is better utilized. In the present embodiment, playback time is increased by use of a constant tape transport speed with part-segmented helical track recording and a bidirectional recording operation during recording and replay.

Abstract: A multiplying amplifier which is controlled in a dB linear manner. Transistors, having a numerical distribution coeffient and having the output voltage to be dB-linearly dependent responsive to a control voltage, are connected to the inputs of a muliplier.

Abstract: An optical recording and/or playback system having tracking and focus regulating circuits. Mechanical shock and/or disc defects are detected and the adverse effects on the tracking and focus regulating circuits are reduced.

Abstract: The invention relates to a switched-mode power supply having a switching transistor which periodically switches through a voltage which is applied to a primary winding of a transformer, having a base current network and having a switching stage for operating the switching transistor, and having a control stage for stabilizing a secondary voltage, the switching transistor having a switched-on phase, an off phase and an oscillation phase during operation. The switching transistor (TP20) of the switched-mode power supply according to the invention is switched through step by step during switching on, via a high-resistance resistor (RP05, RP06, RP07), a primary winding (6, 7) and a capacitor (CP24) . After this, the switched-mode power supply oscillates autonomously via this winding (6, 7) and is controlled by the control stage (TP24) .

Abstract: A drive mechanism for driving independently a first and a second coaxial reel, uses only a single rotatable driving unit for driving both coaxial reels. Independent drive is achieved by reversing the rotation of the driving unit.