Here's Apple's background and summary of the invention: "Traditional computing devices include non-volatile data storage media. One type of non-volatile media is a hard drive that provides relatively high capacity and long term storage of data. The data may include media files (e.g., songs, video, and pictures), software programs, electronic information, and electronic data or files. Existing hard drives include a one or more data disks where data is magnetically stored. Typically, an armature is moved adjacent to the surface of a disk to read or write data from or to the disk respectively while the disk rotates at a particular speed.
"Hard drives can be susceptible to mechanical failure or damage due to a physical shock or vibration. Thus, certain hard drives utilize sensors that detect the physical orientation, surrounding environment, or movement of the hard drive and, thereby, detect the occurrence a shock event. One such sensor is an acceleration sensor. One problem with existing shock sensing mechanisms is that additional components, such as an acceleration sensor, are required to enable shock detection based on surrounding environmental conditions. The additional components can add cost, use limited circuit board space, and increase hard drive circuitry size. Accordingly, there is a need to detect hard drive shock events in a more efficient, less obtrusive, and less costly manner.
"The invention, in various embodiments, addresses deficiencies in the prior art by providing systems, methods and devices that enable the detection of a shock event in a less complex and costly manner without the need for sensing surrounding environmental conditions.
"In one aspect, a data storage device includes a computer readable medium, a motor that rotates the computer readable medium, a current source (e.g., motor driver circuit) that drives the motor using a motor current, a current sensor that detects the motor current and outputs a current level signal, and a processor, in communication with the current sensor, that processes the current level signal to determine whether a shock event has occurred.
"In one configuration, the processing by the processor includes determining whether the current level signal is equal to or greater than a threshold level corresponding to a shock event. In certain configurations, the storage device includes a data store that stores a library of known threshold levels where each threshold level corresponds to a shock event of a known intensity.
"In one feature, shock event intensity is determined by comparing the current level signal to the library of known threshold levels. In another feature, shock event intensity is determined by algorithmically estimating the shock event intensity based on a defined best fit function of the current level signal versus shock event intensity. The function may include at least one of a linear function and a non-linear function. The function may be determined, at least in part, by empirically testing the device over a range of shock event intensities to determine a corresponding range of current level signals (or corresponding changes in current level signals). One approach to measuring shock intensity is to measure gravitational acceleration G applied to a device. The intensity may also include a duration of an applied gravitational acceleration G. One particular shock intensity may be, for example, 70 Gs over a 40 msec period.
"In another configuration, the sensor detects the motor current over a period of time and outputs a plurality of current level signals over a period of time. Thus, the processing may include processing the plurality of current level signals. The processing may include determining a change in the current level between at least two of the plurality of current level signals. The processing may also include determining whether a shock event occurred by determining whether the change in the current level is equal to greater than a threshold level corresponding to a shock event.
"In a further configuration, the processing includes generating a datagram (e.g., plot) of the plurality of current signals over a period of time. Again, the storage device may include a data store for storing a library of known datagrams where each datagram corresponding to a shock event of at least one of a known intensity and duration. The processing may include comparing a generated datagram with the library of known datagrams to identify the shock event. The storage device may be a hard disk drive. The current level signal may be at least one of a current, voltage, information bits, and data packet."
The inventor is Thomas R. Colligan.
For more info on patents, check out Patents.com, a free patent search site.
