A color cathode ray tube employs a shadowmask having substantially vertical slots positioned between a single electron gun and substantially vertical color phosphor stripes on the faceplate of the tube. Piezoelectric bimorph actuators translate the shadowmask back and forth in a direction generally perpendicular to the direction of the slots and stripes in synchronization with field sequential color information to excite the phosphor stripes. In an alternative embodiment, the phosphor screen is moved relative to a fixed shadowmask. During the relative movement between the shadowmask and screen in a first direction, video information is provided from a memory in a first sequential manner, while for relative movement in a second direction, the video information is read out of memory in a reverse direction for executing a reverse raster starting from the bottom of the screen. The slots and phosphor stripes are skewed slightly with respect to one another to maintain proper color registration. In a further embodiment, instead of a shadowmask, a gating array is located between a broad source of electrons and the phosphor screen.

In an apparatus for reproducing signals recorded in a plurality of slant tracks on a recording medium by a rotary head, the signals in the tracks contain a digital information signal in a first predetermined area on the slant tracks and a tracking control signal including a tracking pilot signal and an erase signal in a second predetermined area. When the recorded tracks are reproduced by a rotary playback head having a tracing width greater than the track width, the pilot signals from the adjacent tracks will be detected and compared in level. A tracking signal for controlling the tracking alignment of the rotary playback head is generated in response to the level comparison. The level of the tracking signal is adjusted in response to the level of the tracking control signal.

In a system for recording and reproducing digital signals on a magnetic tape by using a rotary head, in which signals are recorded as a series of slanted tracks without guard bands, a pilot signal that controls tracking alignment of a playback head is recorded at a particular position in a specific pilot signal record region, independent from the information signal record region. The pilot signal is arranged at first predetermined positions separated from the ends of the slanted tracks in the pilot signal record region on every other one of the slanted tracks and at second predetermined positions separated from the ends of the slanted tracks in the pilot signal record region on the alternate ones of the slanted tracks. An erase signal can also be recorded in the pilot signal record region such that a start position of the erase signal corresponds substantially to a center portion of the pilot signal on the adjacent track. When the recorded tracks are reproduced by a rotary playback head having a tracing width greater than the track width, the pilot signals from the adjacent tracks will be detected and compared in level, and the comparison output used to control the tracking alignment of the rotary playback head.

An auto tracking apparatus is arranged to divide a tracing time period of one field of a frame into a plurality of time domains and to sample and hold the envelope detection output signal of a reproduced high frequency signal at every time domain. This sample-and-hold operation is successively made for the following frame and each of the sampled values is compared with the previously value sampled at the corresponding time domain. In accordance with the results of the comparison the displacement of the reproducing head is controlled at every sampling point so that a reproducing head can accurately scan the track along the center line thereof.

There is disclosed herein an apparatus and method for generating a first signal related to the rate of change of a second signal. In particular, a system is disclosed for generating a velocity signal in a sampled data servo system. The apparatus uses three track and hold amplifiers one of which is also a difference amplifier to sample the position error signal at selected times. A "present" track and hold amplifier samples and holds the position error signal during the current frame. After this is done, during the same frame, a "summing" track and hold amplifier having its difference inputs coupled to the outputs of the "present" track and hold amplifier and to a "previous" track and hold amplifier samples the difference between the present position error signal and the value of the position error signal during the previous sample frame. This difference divided by the sample period gives the velocity. After the difference value is sampled, the "previous" track and hold amplifier sample is updated to the amplitude of the position error signal during the current frame in preparation for the calculation during the next frame.