Dynamic information storage or retrieval – Dynamic mechanism subsystem – Mechanism condition or storage medium responsive control
Patent
1993-09-14
1995-12-19
Wolff, John H.
Dynamic information storage or retrieval
Dynamic mechanism subsystem
Mechanism condition or storage medium responsive control
369267, G11B 1928
Patent
active
054775230
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
This invention concerns a method to reduce the access time for rotating storage media with variable angular velocity by displacement of existing kinetic energy, while at the same time the energy consumption is being reduced. The access time for rotating storage media is based on a radial displacement of the reading head and a pending of the correct position of the rotating disc (turning). In order to put a maximum amount of information on a circular, rotating disc surface, some storage media have been constructed according to the CLV (Constant Linear Velocity) method, i.e., the disc is read at a constant velocity along the track, thus constantly changing its angular velocity at recording or reading at different radial distances. Disc storage media with a partition in sectors could have the number of sectors as a step by step function of the radius.
The invention could for example be used on discs of the Compact Disc type, which under continuous reading constantly change their angular velocity by keeping a constant reading speed along the information track. For applications of Compact Discs on computers, so-called CD-ROM, the angular velocity of the disc must in a short time and frequently be altered at each reading, as the information normally is scattered on different locations and thus at different radii on the disc.
Certain sectorized storage media with an extended number of sectors with a extended number of radii also require a change of the angular speed at recording or reading at different radii. Normally a relatively large quantity of energy and a powerful driver unit are required in order to alter the angular velocity in a short time.
The cost for this is traditionally relatively high. Forces of actions and reactions often cause vibrations and thus interferences easily may arise when reading.
OBJECTS AND SUMMARY
A purpose of the invention is to at a low cost considerably reduce the access time in machines of the above mentioned types. The purpose is achieved by the method and the device in accordance with the applications for the patent.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be described below with reference to enclosed drawings, where
FIGS. 1a and 1b show the concept and
FIG. 2 schematically shows how this is done in practice.
DESCRIPTION OF PREFERRED EMBODIMENTS
T rotating system is provided with one or more masses M (FIG. 1a and 1b), attached so that they can be moved radially from the axis of rotation (17), shown at R1 and R2, altering the angular velocity without considerable supply of energy, without forces of reaction and in a very short time.
There is also a possibility to store the energy and have it transferred by Other means to the rotating system, but in a way that does not affect the energy at a changed angular velocity. Thus this concerns a system with a constant energy and an altering rotating inertia.
FIG. 2 shows in detail how this is achieved in practice. Reference numeral (10) represents a disc, connected to the end of a centrally placed spindle (11), which at its other end is a part of a driving gear (12). The spindle (13) protruding from driving gear (12) is connected to a system of at least one weight (16), which can be moved radially towards the axis of rotation (17) by means of an electromagnet or a stepping motor (18). A motor (14) supplies the system with the energy necessary for rotation.
When a change of angular velocity for (10) and (11) is desired, energy can be transferred by a change of the radial position of at least one weight (16) by the electromagnet or stepping motor (18).
The driving gear (12) changes the relationship between the angular velocity for at least one weight (16) and the disc (10) and the spindle (11), so that energy requirements are less for the radial transfer of at least one weight (16), than had they been mounted direcly on the spindle (11).
1. A method for altering the angular velocity of a driven rotating media carrier about an axis of rotation of the media carrier, comprising the steps of:
REFERENCES:
patent: 3947625 (1976-03-01), Greve
patent: 4416006 (1983-11-01), Kitamura et al.
Letscher George J.
Wolff John H.
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