Motion video signal processing for recording or reproducing – Local trick play processing – With randomly accessible medium
Reexamination Certificate
1999-01-11
2002-06-04
Boccio, Vincent (Department: 2615)
Motion video signal processing for recording or reproducing
Local trick play processing
With randomly accessible medium
C386S349000, C386S349000
Reexamination Certificate
active
06400892
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to the fields of disk drive operation and audio storage/playback, and in particular to controlling the operating speed of a disk drive when storing or retrieving data and choosing a disk location for storing the data, the choice of speed and disk location being based on the type of data being stored or retrieved, and the type of operation the retrieved data is used for, e.g., audio playback.
2. Background Information
Many modern electrical devices store and read data. For example, compact disk players read digitized audio data from a plastic disk storage medium with a laser. A video cassette recorder stores and reads audio and video data using magnetic tape as a storage medium. Computer systems are designed to read and store large amounts of data. A computer system will typically employ several types of storage devices, each used to store particular kinds of data for particular computational purposes. Electronic devices may use programmable read-only memory (PROM), random access memory (RAM), flash memory, magnetic tape or optical disks as storage medium components, but many devices, especially computers, store data in a direct access storage device (DASD) such as a hard disk drive.
Although such data storage is not limited to a particular direct access storage device, one will be described by way of example. A hard disk drive typically includes one or more circular magnetic disks as the storage media which are mounted on a spindle. The disks are spaced apart so that the separated disks do not touch each other. The spindle is attached to a motor which rotates the spindle and the disks, normally at a relatively high revolution rate, e.g., 5400 rpm. A disk controller activates the motor and controls the read and write processes which will now be described.
Storage of data on a magnetic disk storage medium entails magnetizing portions of the disk in a pattern which represents the data. In order to write the data onto the magnetic surface of the disk, a small generally ceramic block called a “slider” which contains a magnetic transducer is positioned over the traveling surface of the rotating disk. This transducer is also known as a write element or write head. The write element is typically “flown” at a height of approximately six millionths of an inch from the surface of the spinning disk.
Generally, before storing user data, the disk is formatted (also using the write head) so that its surface is organized into a series of identifiable locations on concentric tracks, according to known methods. As will be described later, the tracks may be further organized into groups of tracks forming a plurality of recording “zones.” When a designated track location on the disk surface is under the write element, the write element is energized to various states by the disk controller, causing the track location below to be magnetized in a way representing the user data to be stored.
Reading recorded data from a magnetized disk is accomplished in a similar fashion. When a read element or read head is flown over the spinning disk, a signal is induced in the read element as it passes over previously magnetized portions of the disk where data has been recorded. To perform a read operation, the disk controller determines the location of the desired recorded data, moves the read head to that location, and captures a signal induced in the read element by the traveling disk when the read element is above the specified location. This induced signal corresponding to the originally recorded data is subsequently processed and the original data reconstructed from the signal induced in the read element. In some devices, the write element also acts as the read element while in others, separate and distinct write and read elements are used. These elements may be disposed on the same head assembly or separate head assemblies.
Generally, each of the head assemblies having the read/write elements of a disk drive are held and positioned by an actuator arm attached to a stepper motor which is directed by the disk drive controller to move the respective head assembly across the radius of the rotating disk from track to track. The elements must be controlled precisely so that the desired user data location is accurately found on the disk.
Further, serious malfunctions, including data loss and physical damage to the disk surface and/or read/write elements, can result if the read/write elements come in contact with data containing portions of the surface of the magnetic disk, especially while it is rotating at high speeds. Generally, a “landing zone,” an area on the disk surface where no data will be written, is provided for the read/write elements to rest on when the disk device is powered down.
The use of disk drives in such devices as portable computers, personal digital assistants and cellular telephones, for example, has increased significantly over the past several years. Devices of this nature typically have a portable battery pack which provides power to the various components of the device when used away from a power outlet. It is important that the battery pack used to supply power to portable devices be compact and lightweight.
However, as portable devices are increasingly used in locations where an external power source is unavailable, for example, traveling on an airplane, it is also increasingly important that the portable devices operate for significant periods of time between recharging of the battery pack. Bigger batteries tend to provide longer use time however they increase the weight of the device. Hence, the desire to achieve a compact and light weight design often competes with a desire for longer usage time of the portable device between charging the battery pack.
In order to increase operating time in portable devices, various steps have been taken to reduce the power consumption of components used in the devices. Moreover, increased efforts have also been made to reduce power consumption in fixed devices, like desk-top computers, in order to more generally conserve energy resources. The Environmental Protection Agency (EPA) now provides for power saving status to be granted to computers meeting certain standards.
Thus, efforts to reduce power consumption of the various components of a computer have been increasingly employed. For example, the central processing unit (CPU) often includes some form of power management function to reduce clock frequency of the CPU when the computer enters a power saving mode, and may act to place various components into a sleep mode where reduced power is used. In general, a power saving mode may be invoked to reduce use of power by a component of the computer when the component is not being used.
In the case of memory storage devices, various power saving techniques have been employed. For example, in disk drives, the spindle motor which rotates the disk storage media uses a large percentage of the total power of the disk drive. In order to conserve power, it has been proposed that the spindle speed of the disk drive be reduced or stopped when the disk drive is not being used. As will be discussed later, depending on head design, reducing spindle speed can adversely affect disk drive reliability if adequate precautions are not taken.
In a typical approach, a normal operating spindle velocity is used by the disk drive during read and write operations to the disk. When the power saving mode is initiated, for example when the disk drive is not accessed for a predetermined period of time, the spindle velocity of the disk is reduced or stopped to conserve power. When an access operation to the disk drive is initiated, the spindle speed is increased until the disk is rotated at the normal operating velocity prior to beginning the read or write operation. In other words, the power saving mode is disengaged and the disk brought up to operational RPM prior to commencement of read and write operations.
A further known technique for conserving storage device power is to use the lightest/smallest
Boccio Vincent
Hollingsworth Mark A.
Lynt Christopher H.
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