U.S. Philips Corporation

Werner A Heijnemans

Nicolaas G Vink

Joris A Nieuwendijk

Albertus A Sluijterman

Albert M Rijckaert

Gijsbertus Bouwhuis

Marcellinus J Annegarn

Johannes H Van Roosmalen

In a helical-scan magnetic-tape apparatus having a scanning unit (102) comprising two diametrically opposed rotatable magnetic-head units (113, 114) which are movable over an actuating distance (A) in two opposite directions (r.sub.1, r.sub.2) by means of actuators (117, 118), the magnetic-head units, with the actuators not activated, are situated at a distance (X) from each other which is smaller than or equal to twice the actuating distance (A). During fast tape transport in a direction opposite to the tape transport direction with which information has been written in tracks on the magnetic tape each magnetic-head unit reads other tracks than those it would read during normal tape transport and/or the read sequence of the tracks is changed.

Vertically distant magnetic head units with piezoelectric error tracking

The volume of the housing of a rear-projection system can be reduced by 20 to 25% when the light beam is obliquely incident on the projection screen. The obliquely incident light beam is deflected towards the viewing space by means of a prism plate (731). By dividing the light-refracting action of the prism plate between the front and rear of the plate only minor light loss occurs.

Compact rear-projection system with obliquely incident light beam

In a method of recording video information in a record carrier, each picture of N.times.M picture elements being divided into subpictures of n.times.m picture elements, the video information of each subpicture is encoded in accordance with a transform coding and recorded on the record carrier. Moreover, corresponding subpictures of two pictures are compared with each other. To both subpictures a motion code is assigned, which motion codes are the same if the subpictures do not differ substantially from one another, but which are not the same if the subpictures differ substantially from each other. The motion is recorded on the record carrier together with the coded information of the subpicture. Moreover, different transform codings may be applied to the subpictures. A higher-order transform coding yields a more accurate information of the subpicture which is encoded. The associated transform code is also recorded on the record carrier. Further, a method of reproducing video information from the record carrier is described and apparatuses for carrying out the two methods are described.

Method and apparatus for recording and/or reproducing video information

A combination of a monochrome cathode-ray tube with a deflection unit for applications which require high resolution. The deflection unit produces a magnetic field having a six-pole component which is positive on the screen side to minimize raster distortion and which, in the deflection center, has a strength and polarity sufficient to minimize spot distortion. Preferably the effective length 1 of the deflection field satisfies the conditon

Combination of a monochrome cathode-ray tube and a deflection unit

A projection screen comprises a single plate of a transparent material. The diffusion in the horizontal direction is provided by filamentary particles which are oriented substantially in one direction in the plate material. Both surfaces of the plate are then capable of performing different functions, yielding a projection screen with an optimally uniform brightness distribution, minimal color faults and maximum contrast.

Projection screen

A color television display device comprising a plurality of picture display tubes for displaying a color television signal. In order to eliminate a flicker effect which particularly occurs for unsatured colors at high luminance, the vertical deflection of a first group of the display tubes as well as the video signals applied thereto are delayed by the same time delay with respect to a second group of the display tubes.

Color television display device comprising a plurality of picture

The stringent requirements regarding convergence (in color display tubes) and spot quality in monochrome display tubes are met by deflection units which produce dynamic multi-pole fields which are strongly modulated. Static multipole fields, which have a dynamic component when an electron beam passes therethrough, are used in cathode ray tube-deflection unit combinations to simulate, a strong modulation of the dynamic multipole deflection fields. In one combination, the production of a negative static eightpole field in the center of the deflection area improves spot quality.

Cathode ray tube having permanent magnets for modulating the deflection

A method of composing self-converging deflection units for color display tubes of the in-line type having the same deflection angles and neck diameters but different screen formats, in which for all screen formats one and the same design of the deflection unit is used, which deflection unit is self-converging for a color display tube of a given screen format and is made self-converging for a color display tube of a different screen format by varying the effective lengths of the line and field deflection coils constructed as saddle-shaped coils of the shell type in opposite senses with the position of their front ends remaining the same.

Self-converging deflection units for color display tubes of different

In a deflection unit for in-line color television display tubes, flux altering elements are provided between the field and line deflection coils, near the center of the field deflection coil, the flux altering means extending substantially parallel to the field deflection field. As a result of these measures, such a deflection unit combines a good astigmatism level with an acceptably small frame coma error and a reduced EW-frame distortion.

Deflection unit for color television display tubes

A deflection unit for in-line color television display tubes having a line deflection coil and a field deflection coil, the field deflection winding having a slightly pronounced barrel-shaped field deflection field in the middle and on the screen side of the deflection unit and being combined with field-forming means (in particular soft-magnetic segments which are placed between the line and field deflection coils) to generate a pronounced pin-cushion-shaped field on the gun side of the deflection unit. As a result of these measures, the deflection unit couples a coma-free field deflection field with a minimum EW-field distortion.

A deflection unit for a color television display tube 1 having a field deflection coil 8 and a line deflection coil 7, in which the line deflection coil is formed by two diametrically oppositely positioned coil portions which, on the side adjacent the tube's screen, have a flared end 17 having a profile with a path length 22 which is longer than the path length 23 of the contour of the outer surface of the tube, so that raster defects are smaller than when the profile of the flared ends conforms to the contour of the tube surface.

Deflection unit for a color television display tube

A deflection device for the electron beam, in, for example, an image pick-up tube, comprising an annular yoke of a magnetic material, having at least two pairs of diametrically arranged, inwards directed cores which are enveloped by deflection coils. On the inner end of each core there is provided a poleshoe in the form of a ring segment, said poleshoes enclosing a deflection space. In order to ensure that the shape of the generated deflection fields can be accurately and reproducibly defined, each coil is situated, viewed from the deflection space, completely behind the associated poleshoe, the spaces between the poleshoes being bridged by intermediate pieces of a non-magnetic material.

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Eindhoven, Netherlands

Werner A Heijnemans