Rewrite apparatus

• US 20090150072A1
• Filed: 12/09/2008
• Published: 06/11/2009
• Est. Priority Date: 12/10/2007
• Status: Active Grant

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Yokoi, Shinichi
• Granted Patent: US 8,185,305 B2
• Time in Patent Office: Days
• US Class Current: 701/209
• CPC Class Codes: G01C 21/26 specially adapted for navigation in a road network
• CPC Class Codes: G11C 16/10 Programming or data input circuits
• CPC Class Codes: G11C 16/3427 Circuits or methods to prevent or reduce disturbance of the state of a memory cell when neighbouring cells are read or written
• CPC Class Codes: G11C 16/3431 Circuits or methods to detect disturbed nonvolatile memory cells, e.g. which still read as programmed but with threshold less than the program verify threshold or read as erased but with threshold greater than the erase verify threshold, and to reverse the disturbance via a refreshing programming or erasing step

Abstract

A rewrite apparatus calculates a risk of destruction of data due to data retention in each file. It is determined whether a refresh start condition is satisfied. The refresh start condition is provided in accordance with the calculated risk. When the refresh start condition is satisfied, it is determined that the possibility to completely execute the refresh is high. The refresh is thereby executed. The rewrite apparatus can thus reduce the possibility to interrupt the refresh of the data stored in the storage medium such as a flash memory.

Claims

1. A rewrite apparatus for reading data stored in a storage medium and writing data into the storage medium, and for executing a refresh which reads data stored in a predetermined area of the storage medium and rewrites the read data in the predetermined area, the rewrite apparatus comprising:

a storage device configured to store a refresh start condition under which the refresh is started in the predetermined area of the storage medium; and

a control device configured to execute a start condition determination for determining whether the refresh start condition stored in the storage medium is satisfied, and for executing the refresh in the predetermined area when it is determined that the refresh start condition is satisfied,

wherein

the refresh start condition stored in the storage device is satisfied when a possibility to execute the refresh completely is high.

2. The rewrite apparatus according to claim 1,

wherein:

the control device is further configured to execute a risk calculation for calculating a risk, which is a degree of destruction of the data stored in the predetermined area; and

only when the risk is equal to or greater than a predetermined value, the start condition determination is executed with respect to the predetermined area.

3. The rewrite apparatus according to claim 1,

wherein:

the refresh start condition is stored in the storage device as one of a plurality of refresh start conditions individually corresponding to risks of destruction of the data stored in the predetermined area; and

the control device is further configured to execute a risk calculation for calculating a risk to thereby determine whether the refresh start condition corresponding to the risk calculated in the risk calculation is satisfied in the start condition determination with respect to the predetermined area.

4. The rewrite apparatus according to claim 1,

wherein:

the predetermined area is included in the storage medium as one of a plurality of predetermined areas;

the refresh start condition is included in the storage device as one of a plurality of refresh start conditions, the refresh start conditions individually corresponding to the predetermined areas; and

the control device is further configured to determine, in the start condition determination, whether the refresh start condition with respect to the predetermined area is satisfied.

5. The rewrite apparatus according to claim 1, further comprising:

a reception device configured to receive a request of a user, and the control device is further configured to set the refresh start condition stored in the storage device in accordance with the request of the user received via the reception device.

6. The rewrite apparatus according to claim 2,

wherein

the control device calculates, in the risk calculation, the risk in accordance with a time elapsed after data is written in the predetermined area.

7. The rewrite apparatus according to claim 2,

wherein

the control device calculates, in the risk calculation, the risk in accordance with a number of reads of data written in the predetermined area.

8. The rewrite apparatus according to claim 6,

wherein:

an area, which stores data in the storage medium, includes one or more storage units;

the rewrite apparatus further comprises a cumulative number identifying device configured to identify a cumulative number of updates of data in at least one of the storage units overlapping with the predetermined area; and

the control device is further configured, in the risk calculation,

to identify the cumulative number of updates of data in the storage units contained in the predetermined area via the cumulative number identifying device, and

to calculate the risk in consideration of the identified cumulative number of updates of data.

9. The rewrite apparatus according to claim 1,

wherein

the rewrite apparatus is mounted to a vehicle.

10. The rewrite apparatus according to claim 9, further comprising:

a route identifying device configured to identify a route of the vehicle; and

a road type identifying device configured to identify a type of a road on which the vehicle is traveling,

wherein;

the refresh start condition stored in the storage device includes a first condition about an expected time during which the vehicle travels on an expressway; and

when the type of the road on which the vehicle is traveling is the expressway, the control device is further configured, in the start condition determination,

to calculate an expected time during which the vehicle travels on the expressway in accordance with the route of the vehicle identified by the route identifying device, and

to consider that the first condition is satisfied when the expected time during which the vehicle travels on the expressway is a predetermined time or over to thereby determine that the refresh start condition is satisfied.

11. The rewrite apparatus according to claim 10,

wherein:

the first condition stored in the storage device includes a condition about a speed of the vehicle; and

the control device is further configured, in the start condition determination, to consider that the first condition is satisfied when the expected time during which the vehicle travels on the expressway is the predetermined time or over and the speed of the vehicle is a predetermined speed or over to thereby determine that the refresh start condition is satisfied.

12. The rewrite apparatus according to claim 9, further comprising:

a route identifying device configured to identify a route of the vehicle;

a congestion section identifying device configured to identify a congestion section; and

a first current position identifying device configured to identify a current position of the vehicle,

wherein;

the refresh start condition stored in the storage device includes a second condition, which is a condition about an expected time during which the vehicle travels in a congestion section; and

the control device is further configured, in the start condition determination,

to calculate the expected time during which the vehicle is traveling in the congestion section in accordance with the route of the vehicle identified by the route identifying device and with the congestion section identified by the route identified by the route identifying device when the current position of the vehicle identified by the first current position identifying device exists in the congestion section identified by the congestion section identifying device, and

to consider that the second condition is satisfied when the expected time during which the vehicle travels in the congestion section is a predetermined time or over to thereby determine that the refresh start condition is satisfied.

13. The rewrite apparatus according to claim 12,

wherein:

the second condition stored in the storage device includes a condition about the speed of the vehicle; and

the control device is further configured, in the start condition determination, consider that the second condition is satisfied when the expected time during which the vehicle travels in the congestion section is a predetermined time or over and when the speed of the vehicle is a predetermined speed or over, to thereby determine that the refresh start condition is satisfied.

14. The rewrite apparatus according to claim 9,

wherein:

an area, which stores data in the storage medium, includes a plurality of write units; and

the control device is further configured to

write data in each of the write units when writing data into the storage medium,

write data read from the write units constituting the predetermined area again in each of the same write units in the refresh, and

execute a drive termination determination for determining whether there is a situation where a drive of the vehicle is terminated during the refresh;

the control device is yet further configured, when determining that there is the situation where the drive is terminated in the drive termination determination, to

interrupt the refresh under execution at a time of a termination of a write of data when the write of data into the write units is under execution, and

interrupt the refresh under execution when the write of data into the write units is not under execution.

15. The rewrite apparatus according to claim 14, further comprising:

a map data acquisition device configured to acquire map data in which positions of facilities and information about the facilities are identified; and

a second current position identifying device configured to identify a current position of the vehicle in a map shown by the map data acquired by the map data acquisition device,

wherein;

the control device is further configured, in the drive termination determination, to

identify the current position of the vehicle via the second current position identifying device,

identify information about facilities around the identified current position of the vehicle in accordance with the map data acquired by the map data acquisition device, and

determine whether there is the situation where the drive of the vehicle is terminated in accordance with the information about the facilities around the identified current position of the vehicle.

16. The rewrite apparatus according to claim 14, further comprising:

a destination identifying device configured to identify a destination of the vehicle; and

a second current position identifying device configured to identify the current position of the vehicle,

wherein

the control device is further configured, to determine, in the drive termination determination, whether there is the situation where the drive of the vehicle is terminated in accordance with the destination of the vehicle identified by the destination identifying device and the current position of the vehicle identified by the second current position identifying device.

17. The rewrite apparatus according to claim 9,

wherein:

an area, which stores data in the storage medium, includes a plurality of write units;

the control device is further configured to

write data into each of the write units when writing the data into the storage medium,

write data read from the write units constituting the predetermined area in the refresh, and

execute a normal execution determination for determining whether a normal execution of the refresh is possible during the refresh; and

the control device is yet further configured, when determining that the normal execution of the refresh is impossible in the normal execution determination, to

interrupt the refresh under execution at a termination of the write of data when the write of data into the write units is under execution, and

interrupt the refresh under execution when the write of data into the write units is not under execution.

18. The rewrite apparatus according to claim 17, further comprising:

a vehicle speed acquisition device configured to acquire a speed of the vehicle,

wherein

the control device is further configured, in the normal execution determination, to determine that the normal execution of the refresh is impossible when the speed acquired by the vehicle speed acquisition device is a predetermined value or over.

19. The rewrite apparatus according to claim 17, further comprising:

a road information identifying device configured to identify information about a road on which the vehicle is traveling,

wherein

the control device is further configured, in the normal execution determination,

determine whether the vehicle travels on a rough road, and

determine that the normal execution of the refresh is impossible when the vehicle travels on the rough road in accordance with the information about the road on which the vehicle is traveling, the information being identified by the road information identifying device.

20. The rewrite apparatus according to claim 9, further comprising:

a slot configured to load the storage medium for writing and reading data;

a blocking device configured to block a removal of the storage medium loaded from the slot by covering the slot; and

a locking device configured to lock the blocking device,

wherein

the control device is further configured to lock the blocking device covering the slot by use of the locking device when writing data into the storage medium.

21. The rewrite apparatus according to claim 9,

wherein:

a steering wheel position moving device disposed to the vehicle to move a steering wheel to a predetermined position at a start of a drive;

the rewrite apparatus further comprising a slot configured to load the storage medium for writing and reading data; and

the slot is disposed to a portion blocked due to a movement of the steering wheel by the steering wheel moving device.

22. The rewrite apparatus according to claim 9, comprising:

a slot configured to load the storage medium for writing and reading data,

wherein

the slot is disposed to a contact surface for a door of a body of the vehicle or to a contact surface for the body at the door of the vehicle.

23. A program storage medium containing instructions readable and executable by a computer, the instructions for causing the computer to function as the control device of the rewrite apparatus according to claim 1.