Abstract:
It is known to supply a test signal periodically to the deflector circuit, to compare the test deflection current (iT) flowing in the deflector circuit with a reference value (Uref) in a comparator (7) and to use the resultant signal (Us2) to change the test deflection current (iT) and the grid deflection current (iA) stepwise. The aim is to prevent the grid deflection current from oscillating about the reference value. The test procedure with the oscillating procedure is carried out only for an imperceptible time during the picture, and the grid deflection current (iA) is corrected only if the test deflection current (iT) deviates from the reference value (Uref) by more than one step. In particular for a projection TV set.
Abstract:
It is known, besides the actual image, also to set up a grid model with intersections for which the raster corrections are found and stored. The purpose is to provide a process for adjustment which ensures a properly centred position of the actual image and grid model. First of all the image (2) is centred at its exact position on the screen (1). The time position of the control pulses generating the grid model (SH, SV) relatively to the deflection raster is set. Especially for convergence correction in a projection television set.
Abstract:
The invention converns a coupling part (VS) which mates with a matching part (VB) and can be connected to a cable (K) with at least one lead (A) and one insulating layer (I). Electric or optical fibre cables, for example, are used to transmit information between two devices. A suitable coupling part is required for both type of cable. The coupling part (VS) disclosed, which can transmit both electrical and optical signals, has at least one electrical contact (S) and one optical contact (L), preferably of the same cross-section as the insulating layer (I) of the cable (K), which is made from optically conductive material. The coupling part is suitable for single- or multi-core cables, coaxial cables, ribbon cables, mains cables, etc.
Abstract:
In a data reproduction device, the data signals (HF) supplied by a photodetector (PD) are disrupted by dirt deposited on the recording support or by vibrations communicated to the equipment. When the light beam (L) for data exploration jumps several tracks as a result of the so-called track-jumping phenomenon, the upper curve envelope of the data signals (HF) assumes a sinusoidal shape. In order to determine immediately whether disruption is caused by dirt on the recording support or by equipment vibrations, and/or if the light beam jumps tracks, the upper curve envelope of the data signals (HF), coupled in d.c., is compared with an upper limit value (SO), and the lower curve envelope with a lower limit value (SU). If the upper curve envelope descends below the upper limit value (SO) a track-jump has occurred. If the lower curve envelope exceeds the lower limit value (SU), the cause is vibration of the device or dirt or scratches on the data support. The invention concerns compact disc play-back devices, draw-disc, video-disc players and magneto-optical equipment.
Abstract:
When optical sensor signals in particular are evaluated, accurate determination of useful signal levels is often essential. For example, marks of different width are located on the rotor of a head drum motor, and the narrow markings produce sensor signals with a small peak value and the broad marks produce signals with a large peak value. The former signals are used to commute the head drum motor and the latter signals for reversing the magnetic heads of a video recorder. It is not always possible to distinguish between the different amplitudes of the signals because of tolerances of the marks and of the components of the evaluation circuit. The invention provides a control circuit which maintains the mean of the peak values of selected signal components constant. Video recorders, CD players, general regulation of signal components.
Abstract:
A focussing device for picture reproduction units is disclosed. In picture reproduction units, such as projection television sets, the electronic beam is not focussed with a uniform quality over the whole surface of the screen. The object of the invention is therefore to ensure a uniform focussing quality over the whole surface of the screen. Voltage values required for optimal focussing are determined for picture points distributed on the screen, then are recorded as digital signals in memories (M) and successively supplied to the focussing electrode of the picture tube (1, 2, 3) during reproduction. The device is particularly useful for focussing in a projection television set.
Abstract:
In electrical appliances with motors, which are used, for example, as a tape, disk or head drive, the problem of setting different operating modes as rapidly as possible is conventionally solved by supplying a current appreciably greater than or less than the stationary value to the coil when these changes are made. As soon as the final value of the rotational speed or torque is reached, the current is changed to the stationary value corresponding to the modified operating mode. According to the invention, the moment at which the coil current is changed is also changed in the acceleration, retardation and/or loading phase. Both the process and the circuit are used for preference in video and audio recorders.
Abstract:
A device is useful for correcting the grid in a TV set. In known grid-correction devices, in particular for correcting the convergence, correction values for certain pixels determined by points of intersection (K) of a grid pattern are stored in memories. In devices with several operating modes with different deflection amplitudes, fresh correction values must be stored for each operating mode, because the points of intersection shift on the picture area. In order to reduce the number of memories in operating modes with different deflection amplitudes, the instantaneous position of the control pulses for the grid pattern is varied so that the points of intersection (K) are always located at the same spatial positions of the picture area (1). The device is particularly useful for correcting the convergence in projection TV sets.
Abstract:
A device is useful for automatically adjusting a deflection grid on a picture area. A beam of light from the deflection grid falls onto a light sensor (3) arranged on the picture surface (1). In order to obtain a simple sensor unit (3) which detects the deflection of the beam (L) in all directions, the sensor unit (3) contains four separate sensors (A to D) arranged in a four-quadrant detector. The control signals for the horizontal and vertical deflection used to adjust the beam are obtained by different combinations of the output signals of the sensors (A and D). This device is particularly useful for stabilizing the position of the picture and the amplitude of the deflection in a projection TV set.