# US 8,751,855 B2 · Method and memory device for generating a time estimate

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- Number: US 8,751,855 B2
- Document ID: US8751855B2
- Status: Granted
- Kind: B2
- Application number: 13/862,978
- Filed: 2013-04-15
- Published: 2013-09-05
- Granted: 2014-06-10
- Earliest claimed: 2009-08-17
- Assignees: SanDisk IL Ltd.
- Applicants: Rahav Yairi; Itzhak Pomerantz; Itai Dror; Ori Stern
- Inventors: Rahav Yairi; Itzhak Pomerantz; Itai Dror; Ori Stern
- Web page: https://patentgrep.com/patent/US8751855B2

## CPC

- G06F 1/14: Time supervision arrangements, e.g. real time clock
- G06F 21/10: Protecting distributed programs or content, e.g. vending or licensing of copyrighted material (protection in video systems or pay television H04N7/16) {; Digital rights management [DRM]}
- G06F 2221/2151: Time stamp
- G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N)

## Abstract

A method and memory device for generating a time estimate are provided. In one embodiment, a memory device generates a time estimate from time stamps in file system metadata for a plurality of files stored in the memory device and uses the time estimate to perform a time-based activity in the memory device. In another embodiment, a memory device generates a time estimate from time stamps stored in a plurality of files stored in the memory device and uses the time estimate to perform a time-based activity in the memory device. In yet another embodiment, a memory device obtains a plurality of time stamps, selects one or more of the plurality of time stamps based on validity rankings, generates a time estimate from the selected time stamp(s), and uses the time estimate to perform a time-based activity in the memory device.

## Claims

### Claim 1

A method for generating a time estimate in a memory device, the method comprising:
performing by a processor in a memory device embedded in a host:
storing in the memory device: (i) a plurality of files and (ii) file system metadata for each of the plurality of files, wherein file system metadata for a given file contains a time stamp associated with that file;
generating an estimate of what time it is from the time stamps in the file system metadata for the plurality of files, wherein the memory device does not have a real-time clock; and
using the estimate of what time it is to perform a time-based activity in the memory device.

### Claim 2 (depends on 1)

The method of claim 1, wherein the time-based activity comprises sending a request to the host for scheduling a memory device management task.

### Claim 3 (depends on 1)

The method of claim 1, wherein the file system metadata comprises an entry in a file allocation table.

### Claim 4 (depends on 1)

The method of claim 1, wherein the time stamp comprises one or more of the following:
a file creation time, a last access time, and a last modification time.

### Claim 5 (depends on 1)

The method of claim 1, wherein the time-based activity comprises one or more of the following:
time-based scheduling of a service, time-based scheduling of a memory device management activity, monitoring of content license expiration, time-based advertising, and time stamping a file stored in the memory device.

### Claim 6 (depends on 1)

The method of claim 1, wherein the time-based activity comprises attaching the estimate of what time it is to an undated file.

### Claim 7 (depends on 1)

The method of claim 1, wherein the time-based activity comprises attaching the estimate of what time it is to file system metadata of an undated file.

### Claim 8 (depends on 1)

The method of claim 1, wherein the time-based activity comprises invaliding a previously-recorded time stamp in view of a more-accurate time stamp.

### Claim 9 (depends on 1)

The method of claim 1, wherein the time-based activity comprises providing the estimate of what time it is to the host.

### Claim 10 (depends on 1)

The method of claim 1, wherein the estimate of what time it is comprises a time interval.

### Claim 11 (depends on 1)

The method of claim 1 further comprising receiving a rule to perform a time-based activity in the memory device.

### Claim 12 (depends on 11)

The method of claim 11 further comprising monitoring a memory device event and scheduling the time-based activity based on the rule and monitored event.

### Claim 13 (depends on 1)

The method of claim 1 further comprising receiving a time stamp from an entity external to the memory device and generating the estimate of what time it is using both the time stamp received from the entity and the time stamps in the file system metadata for the plurality of files.

### Claim 14 (depends on 1)

The method of claim 1 further comprising tracking an active time of the memory device, and wherein the estimate of what time it is generated by adjusting the time stamps by the active time.

### Claim 15

A method for generating a time estimate in a memory device, the method comprising:
performing by a processor in a memory device embedded in a host:
storing a plurality of files in the memory device, wherein each of the plurality of files stores a respective time stamp;
generating an estimate of what time it is from the time stamps stored in the plurality of files, wherein the memory device does not have a real-time clock; and
using the estimate of what time it is to perform a time-based activity in the memory device.

### Claim 16 (depends on 15)

The method of claim 15, wherein the time-based activity comprises sending a request to the host for scheduling a memory device management task.

### Claim 17 (depends on 15)

The method of claim 15, wherein one of the plurality of files contains an email message, and wherein the time stamp is a time the email message was sent or received.

### Claim 18 (depends on 15)

The method of claim 15, wherein one of the plurality of files contains a digital picture, and wherein the time stamp is a time the digital picture was taken.

### Claim 19 (depends on 15)

The method of claim 15, wherein the time-based activity comprises one or more of the following:
time-based scheduling of a service, time-based scheduling of a memory device management activity, monitoring of content license expiration, time-based advertising, and time-stamping a file stored in the memory device.

### Claim 20 (depends on 15)

The method of claim 15 further comprising receiving a rule to perform a time-based activity in the memory device.

### Claim 21 (depends on 20)

The method of claim 20 further comprising monitoring a memory device event and scheduling the time-based activity based on the rule and monitored event.

### Claim 22 (depends on 15)

The method of claim 15 further comprising receiving a time stamp from an entity external to the memory device and generating the estimate of what time it is using both the time stamp received from the entity and the time stamps stored in the plurality of files.

### Claim 23 (depends on 15)

The method of claim 15, wherein the time-based activity comprises attaching the estimate of what time it is to an undated file.

### Claim 24 (depends on 15)

The method of claim 15, wherein the time-based activity comprises attaching the estimate of what time it is to file system metadata of an undated file.

### Claim 25 (depends on 15)

The method of claim 15, wherein the time-based activity comprises invaliding a previously-recorded time stamp in view of a more-accurate time stamp.

### Claim 26 (depends on 15)

The method of claim 15, wherein the time-based activity comprises providing the estimate of what time it is to the host.

### Claim 27 (depends on 15)

The method of claim 15, wherein the estimate of what time it is comprises a time interval.

### Claim 28 (depends on 15)

The method of claim 15 further comprising tracking an active time of the memory device, and wherein the estimate of what time it is generated by adjusting the time stamps by the active time.

### Claim 29

A method for generating a time estimate in a memory device, the method comprising:
performing by a processor in a memory device embedded in a host:
obtaining a plurality of time stamps, each time stamp being associated with a respective source having a respective validity ranking;
selecting one or more of the plurality of time stamps based on the validity rankings;
generating an estimate of what time it is from the selected time stamp(s), wherein the memory device does not have a real-time clock; and
using the estimate of what time it is to perform a time-based activity in the memory device.

### Claim 30 (depends on 29)

The method of claim 29, wherein the time-based activity comprises sending a request to the host for scheduling a memory device management task.

### Claim 31 (depends on 29)

The method of claim 29, wherein a time stamp is obtained for one or more of the following:
file system metadata stored in the memory device, a file stored in the memory device, an entity external to the memory device, a host agent on a host in communication with the memory device, a time server in communication with the memory device, a second estimate of what time it is generated by the memory device, and an elapsed time measured by a deterioration of memory cells in the memory device.

### Claim 32 (depends on 29)

The method of claim 29, wherein the time-based activity comprises one or more of the following:
time-based scheduling of a service, time-based scheduling of a memory device management activity, monitoring of content license expiration, time-based advertising, and time stamping a file stored in the memory device.

### Claim 33 (depends on 29)

The method of claim 29 further comprising receiving a rule to perform a time-based activity in the memory device.

### Claim 34 (depends on 33)

The method of claim 33 further comprising monitoring a memory device event and scheduling the time-based activity based on the rule and monitored event.

### Claim 35 (depends on 29)

The method of claim 29, wherein the time-based activity comprises attaching the estimate of what time it is to an undated file.

### Claim 36 (depends on 29)

The method of claim 29, wherein the time-based activity comprises attaching the estimate of what time it is to file system metadata of an undated file.

### Claim 37 (depends on 29)

The method of claim 29, wherein the time-based activity comprises invaliding a previously-recorded time stamp in view of a more-accurate time stamp.

### Claim 38 (depends on 29)

The method of claim 29, wherein the time-based activity comprises providing the estimate of what time it is to the host.

### Claim 39 (depends on 29)

The method of claim 29, wherein the estimate of what time it is comprises a time interval.

### Claim 40 (depends on 29)

The method of claim 29 further comprising tracking an active time of the memory device, and wherein the estimate of what time it is generated by adjusting the selected time stamp(s) by the active time.

### Claim 41 (depends on 29)

The method of claim 29, wherein a validity ranking of a source is determined by the source's time quality.

### Claim 42

A memory device comprising:
a memory configured to store a plurality of files and file system metadata for each of the plurality of files, wherein each file comprises a respective time stamp, and wherein file system metadata for a given file contains a time stamp associated with that file; and a controller in communication with the memory and operative to perform the following:
generate an estimate of what time it is from one or both of the time stamps in the file system metadata for the plurality of files and the time stamps stored in the plurality of files, wherein the memory device does not have a real-time clock, and wherein the memory device is embedded in a host; and
use the estimate of what time it is to perform a time-based activity in the memory device.

### Claim 43 (depends on 40)

The memory device of claim 40, wherein the time-based activity comprises sending a request to the host for scheduling a memory device management task.

### Claim 44 (depends on 42)

The memory device of claim 42, wherein the file system metadata comprises an entry in a file allocation table.

### Claim 45 (depends on 42)

The memory device of claim 42, wherein the time stamp in the file system metadata comprises one or more of the following: a file creation time, a last access time, and a last modification time.

### Claim 46 (depends on 42)

The memory device of claim 42, wherein the time-based activity comprises one or more of the following:
time-based scheduling of a service, time-based scheduling of a memory device management activity, monitoring of content license expiration, time-based advertising, and time stamping a file stored in the memory device.

### Claim 47 (depends on 42)

The memory device of claim 42, wherein the time-based activity comprises attaching the estimate of what time it is to an undated file.

### Claim 48 (depends on 42)

The memory device of claim 42, wherein the time-based activity comprises attaching the estimate of what time it is to file system metadata of an undated file.

### Claim 49 (depends on 42)

The memory device of claim 42, wherein the time-based activity comprises invaliding a previously-recorded time stamp in view of a more-accurate time stamp.

### Claim 50 (depends on 42)

The memory device of claim 42, wherein the time-based activity comprises providing the estimate of what time it is to the host.

### Claim 51 (depends on 42)

The memory device of claim 42, wherein the estimate of what time it is comprises a time interval.

### Claim 52 (depends on 42)

The memory device of claim 42, wherein the controller is further operative to receive a rule to perform a time-based activity in the memory device.

### Claim 53 (depends on 52)

The memory device of claim 52, wherein the controller is further operative to monitor a memory device event and schedule the time-based activity based on the rule and monitored event.

### Claim 54 (depends on 42)

The memory device of claim 42, wherein the controller is further operative to receive a time stamp from an entity external to the memory device and generate the estimate of what time it is using both the time stamp received from the entity and the one or both of the time stamps in the file system metadata for the plurality of files and the time stamps stored in the plurality of files.

### Claim 55 (depends on 42)

The memory device of claim 42, wherein the controller is further operative to track an active time of the memory device, and wherein the estimate of what time it is is generated by adjusting the time stamps by the active time.

### Claim 56 (depends on 42)

The memory device of claim 42, wherein each time stamp source has a validity ranking, and wherein the controller is further operative to select one or more of a plurality of time stamps based on the validity rankings, wherein the estimate of what time it is generated from the selected time stamp(s).