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With linear storage tapes, the head reads the data by passing over the numerous data tracks on the tape in which the data is stored. If the data tracks were wide enough, the head could easily pass over the tracks without guidance. However, in high-density storage formats, the track width is extremely narrow so the only way to keep the head oriented on the data tracks is to carefully guide its position. In the case of data storage, a pre-recorded servo signal is used to guide the head along a track range called the servo tracks. Since these tracks serve as the standard for guiding the head, they are just like train tracks.
For a train to run safely, the rails must be laid equally spaced throughout the track length. Sony’s unique servo writer enables the error of spacing to be extremely small. So even when tapes deform because of environmental factors such as temperature and humidity, the servo tracks remain safely uniform. |
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| With the linear type magnetic writing and reading format, the path width for the passing reading head is usually narrower than the width of the recorded data pattern (data track width). |
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| Unfortunately, tape deformation can cause expansion and contraction of the data track width and the gap between the servo tracks, preventing the reading head from passing over all data tracks. This is called the “off track” condition and it can result in important data not being read. |
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| Sony uses a base film with enhanced rigidity for its storage tapes and controls the tapes to contract or expand properly. This allows elimination of reading errors, realizing reliable recording and playback characteristics. |
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| If the servo signal bandwidth was 1400mm, the same width as a train track, Sony minimizes the variation in track width from temperature-humidity differences to only 2mm. In fact, we now have the technology to reduce distortion: tens of nanometers (one nanometer is one-millionth of a millimeter) to one-half. This precise control is now being applied to Sony storage tapes. |
