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World of Blu-ray Drive > Pioneer's world of Blu-ray¡iTechnologies of Pioneer¡j

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Stable and secure with large data capacity
Structure and types of Blu-ray discs
Methods for using a Blu-ray Drive
Technologies of Pioneer
 

Specifications of the Blu-ray standard have been strictly formulated down to the tiniest detail in order to thoroughly eliminate problems arising from compatibility. How accurately and how reliably the standard is realized, as well as how good the operability and the comfortable feel is in operating it, are when the individual characteristics of each manufacturer appear and when gaps in the technologies and experience show up. Let us now determine the kind of advantages offered in the Blu-ray Disc Drive from Pioneer.

 

Before the laser beam passes through the object lens of the Blue-ray Drive from Pioneer it passes through a component called the "multi-functional liquid crystal panel". This liquid crystal panel is a technology for inhibiting focal point drift referred to as "coma aberration" that occurs due to the minute curvature of BD and DVD, as well as focal point dispersion, referred to as "astigmatism", which is unavoidable with optical lenses. This technology makes it possible for the laser beam to trace along the recording layer on the disc in an accurate manner, preventing minute deformations from developing in the disc itself, vibrations from spinning, compatibility issues developing due to changes that occur from aging, as well as a variety of other problems. A stable and secure feeling is acquired by being part of a completely different class. And such are the technologies of Pioneer.

Recording high-definition picture quality video on discs

¡´ Liquid Crystal Tilt
In order to read and write data accurately on a microscopic level, with a track pitch of 0.32μm, it is necessary to ensure that the focal point does not drift in relation to the pit, by directing the light onto the disc in a perpendicular direction. Compensation for a "coma aberration" and "spherical aberration" becomes a major factor in that aspect.
Since it is difficult to produce media with a perfectly flat surface, due to the manufacturing process, a slight inclination can occur when it is loaded into equipment. Such an inclination causes the "coma aberration", which prevents an image formation of the optical spot on which the laser beam is supposed to focus into a point, resulting in a trailing effect. Furthermore, a "spherical aberration" can occur, which causes a spot of light to appear blurry, as a portion of the light beam can drift in a direction towards the vicinity of the lens away from where the focal position should be. This is considered to be rooted in the variance of the thickness of the protective layer of the medium.
Many technologies have been developed to compensate for such issues. Most of these technologies, however, deal only with compensation for the "coma aberration", involving the movement of the light pickup through a mechanical means, thus various complex servo controls, such as an actuator, focus and tracking became necessary, which in turn contributed towards an increase in the incidents of mechanical problems, adding to the costs.
The technology developed by Pioneer, on the other hand, is known as the "Liquid Crystal Tilt". A characteristic of liquid crystal is that when voltage is applied its refraction factor changes. This characteristic was exploited with the placement of a component called "liquid crystal phase compensation element" between the laser light source and the object lens, to change the refraction factor by applying voltage when the medium is tilted. Furthermore, drifts of a focal position arising from variations in thickness of the protective layer on the medium are also counteracted and compensated using this element.

Recording high-definition picture quality video on discs

The "Liquid Crystal Tilt", Pioneer's proprietary technology, is capable of compensating for both "spherical aberration" and "coma aberration" with a single element and no complex mechanism is required since there is no need to move the optical pickup, leading to the simplification of a configuration for the optical pickup and a reduction in the potential problems that may occur.

Recording high-definition picture quality video on discs

¡´ Smart Laser Driver
The "Strategy Circuit", which adjusts the recording signals in appropriate conditions to record optimum bits on the disc, is ordinarily placed on the main substrate. Signal adjustments performed by the Strategy Circuit must be completed in a short amount of time when the recording speed is increased, requiring adjustments to be made with the resolution of about one-twentieth of the clock frequency, which is 9.3ns when writing is being executed at quadruple the speed. In such circumstances, transmission distortions occur in the flexible cable that is connected between where the signal adjusted by the main substrate reaches the optical pickup and with the actual drive signals for the laser. Fluctuations exceeding this resolution occur, potentially resulting in deterioration of the recording characteristics, such as drifts to the recording waveforms. Such a situation occurs more frequently as the writing speed is increased.
The "Smart Laser Driver" therefore has a Strategy Circuit built into the laser driver IC, in order to perform strategy adjustments on the side of the optical pickup. There is no difference in that distortion occurs with the signal transmitted by the main substrate, but since it is reproduced into clean clock waveforms by the PLL Circuit built into the Smart Laser Driver, there is no impact to the recording characteristics. The Smart Laser Driver is the technology key to stable writing at even higher speeds in the future.

Recording high-definition picture quality video on discs

 
Blu-ray is a group of extremely precise technologies. Ensuring that data read or written on a BD is accurate and reliable is obviously essential, but how the handled data itself is polished and utilized as data signals with a high degree of purity is where the technological capabilities of a manufacturer become apparent. Technologies drawing a lot of attention, such as the "Cross Talk Canceller" and "Limit Equalizer", are used in the Blu-ray Drive from Pioneer.
The "Cross Talk Canceller" is a technology for removing the unnecessary signals of the data read from a BD. The laser beam of the Blu-ray reads data by accurately tracing "tracks" on the BD, but since the track pitch is only 0.32 microns small, there are occasions when data from neighboring tracks are picked up. In such instances, the data read from neighboring tracks, rather than the track from which the data should have been read, are filtered out to significantly reduce the adverse effects. This results in a dramatic improvement in the data reading accuracy for cases when the angle between the laser beam and the surface of the disc drifts minutely.
The "Limit Equalizer" is a patented technology for clearing the soiling of signals, which occur due to the optical mechanism segments, etc., when the data is read from the BD. This significantly reduces distortion along the time axis, referred to as "jitter", and allows the drive to read the signal waveform in a beautiful and accurate manner, and resulting in the accurate and high quality reading and writing of signals. Such are the technologies of Pioneer.

Recording high-definition picture quality video on discs
 
In order to ensure the accurate reading and writing of data on the BD, it is necessary to sustain accurate and highly reliable operations at all times, with little vibration and quiet, in terms of operating noise. The "Ultra DRA" is a mechanism for significantly reducing the mechanical vibration of BD, which is spinning at high speeds.
Ordinarily a damper (vibration suppressing structure) is installed between the chassis of the Drive and the transverse mechanism (the recording and replaying mechanism of the disc). It is difficult to completely suppress the vibration that occurs in the transverse mechanism with this damper alone. For this reason, Pioneer mounted a damper, made of a weight and rubber, on the transverse mechanism. This mechanism swings in the reverse direction from the vibration caused by the high speed rotation of the disc, etc., to absorb unnecessary vibrations. The accuracy for reading significantly improves and guarantees stable operations even when the unit is placed on its side, since the vibration of the pickup lens is reduced.
 

The reliability of a Blu-ray Drive, crammed with parts that generate heat inside a small chassis, is impacted heavily by the good or bad quality of the implemented heat countermeasure. Blu-ray Drives from Pioneer are loaded with an internal circulating air cooling mechanism that takes advantage of the rotation of the disc to inhibit excessive local heating of the body and the disc. This mechanism improves the flow of air (air current) within the chassis, crammed with parts, while inhibiting noise, to increase reliability and stability. Such are the technologies of Pioneer.