HDCAM SR TAPE FAQ's Section Page 2:

Building on years of experience in metal tape technology, Sony's Media Research and Development group in Japan once again successfully teamed up with their recorder R&D counterparts to rise to a great challenge; the creation of a tape capable of recording a video transfer rate of 440Mbps, more than 3x the transfer rate used with the HDCAM format. This was accomplished through the development of unique and innovative manufacturing processes relative to surface smoothness, filtration of ultrafine metal particles, and physical durability. Achieving high-density recording, in a cassette size sufficiently small enough to enable practical applications, requires media as sophisticated as the recording format it supports.

The key technologies that serve as the foundation for this new breed of tape start with the size of the metal particles. The particles used for HDCAM SR are half the length and only ¨ú the diameter of the particles used for HDCAM tape. Considering the smallest recorded wavelength is only 0.294¥ìm, the aerial density (particles per square inch) plays an important role in the tapes ability to record a high density signal (Fig. 1). Consider the analogy of a printer's dpi (dots per inch) specification where the higher the dpi value, the more detail that can be printed on a piece of paper. This is very similar to the recording density on tape where the higher the aerial density, the more information that can be recorded per square inch. These particles also retain a high amount of energy. The output of the HDCAM SR tape exhibits a 6dB increase compared to HDCAM tape, which equates to twice the output.


A non-magnetic layer is used to increase the tape thickness and reduce self-demagnetization. With new particles exhibiting such high energy they can actually demagnetize the recording on adjacent layers (commonly referred to as print-through). To guard against this print-through effect a non-magnetic layer is used to reduce the effects of self-demagnetization (Fig. 2). A thinner magnetic layer is also used because shorter wavelengths require less depth of the coating for recording. In addition, this layer plays a part in creating an ultra-smooth tape surface.


The tapes surface smoothness is another key technology that contributes significantly to the record/playback of such short wavelengths. It is an absolute must that the record/playback heads in the equipment maintain intimate contact with the tape for sustained data transfer integrity with minimal errors. To this point, the tape surface has been further calendared (i.e. squeezed between highly polished rollers) to maximize head-to-tape contact (Fig. 3). The incorporation of a new dispersion agent, which disperses the particles evenly in the coating, coupled with a new dispersion system, which enables finer filtering prior to coating, also contributes to an increase in tape smoothness.

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