1. A method for writing information into a variable resistance nonvolatile memory device including a variable resistance element, the method comprising:
(A) applying an initial voltage pulse to the variable resistance element for changing a resistance value of the variable resistance element;
(B) performing a first verify operation at least once after applying the initial voltage pulse, the first verify operation including
(b1) reading the resistance value of the variable resistance element,
(b2) determining whether or not the read resistance value satisfies a first determination condition, and
(b3) applying a voltage pulse to the variable resistance element when the read resistance value does not satisfy the first determination condition;
(C) stopping the first verify operation when a number of times of the first verify operation exceeds a predetermined number; and
(D) performing a second verify operation at least once when the number of times of the first verify operation exceeds the predetermined number, the second verify operation including
(d1) reading the resistance value of the variable resistance element,
(d2) determining whether or not the read resistance value satisfies a second determination condition that is looser than the first determination condition, and
(d3) applying the voltage pulse to the variable resistance element when the read resistance value does not satisfy the second determination condition.
2. The method according to claim 1, wherein:
in the first verify operation, the read resistance value is determined not to satisfy the first determination condition when the read resistance value is higher than a first threshold value,
in the second verify operation, the read resistance value is determined not to satisfy the second determination condition when the read resistance value is higher than a second threshold value, and
the second threshold value is higher than the first threshold value.
3. The method according to claim 1, wherein:
in the first verify operation, the read resistance value is determined not to satisfy the first determination condition when the read resistance value is lower than a third threshold value,
in the second verify operation, the read resistance value is determined not to satisfy the second determination condition when the read resistance value is lower than a fourth threshold value, and
the fourth threshold value is lower than the third threshold value.
4. The method according to claim 2, wherein:
the initial voltage pulse is for changing the variable resistance element from a first resistance state to a second resistance state having a lower resistance value than the first resistance state does, and
the second threshold value is lower than a reading reference resistance value that is a reading criterion for determining whether the variable resistance element is in the first resistance state or the second resistance state.
5. The method according to claim 3, wherein:
the initial voltage pulse is for changing the variable resistance element from a second resistance state to a first resistance state having a higher resistance value than the second resistance state does, and
the fourth threshold value is higher than a reading reference resistance value that is a reading criterion for determining whether the variable resistance element is the first resistance state or the second resistance state.
6. The method according to claim 1, wherein the voltage pulse is different from the initial voltage pulse in a voltage value or a pulse width.
7. The method according to claim 1, wherein the voltage pulse is same as the initial voltage pulse in a voltage value and a pulse width.
8. The method according to claim 1, further including
(E) stopping the performance of the second verify operation when the number of times of the second verify operation reaches a predetermined upper limit.
9. The method according to claim 8, further comprising:
(F) performing a third verify operation at least once after the number of times of the second verify operation reaches the predetermined upper limit, the third verify operation including
(f1) reading the resistance value of the variable resistance element,
(f2) determining whether or not the read resistance value satisfies the first determination condition, and
(f3) applying a voltage pulse to the variable resistance element when the read resistance value does not satisfy the first determination condition.
10. A variable resistance nonvolatile memory device comprising:
a memory cell array including a variable resistance element; and
pulse application circuitry operative to:
(A) apply an initial voltage pulse to the variable resistance element for changing a resistance value of the variable resistance element;
(B) perform a first verify operation at least once after applying the initial voltage pulse, the first verify operation including (b1) reading the resistance value of the variable resistance element, (b2) determining whether or not the read resistance value satisfies a first determination condition, and (b3) applying a voltage pulse to the variable resistance element when the read resistance value does not satisfy the first determination condition; and
(C) stop the first verify operation when a number of times of the first verify operation exceeds the predetermined number; and
(D) perform a second verify operation at least once when the number of times of the first verify operation exceeds a predetermined number, the second verify operation including (d1) reading the resistance value of the variable resistance element, (d2) determining whether or not the read resistance value satisfies a second determination condition that is looser than the first determination condition, (d3) applying the voltage pulse to the variable resistance element when the read resistance value does not satisfy the second determination condition.
11. The variable resistance nonvolatile memory device according to claim 10, wherein:
in the first verify operation, the read resistance value is determined not to satisfy the first determination condition when the read resistance value is higher than a first threshold value,
in the second verify operation, the read resistance value is determined not to satisfy the second determination condition when the read resistance value is higher than a second threshold value, and
the second threshold value is higher than the first threshold value.
12. The variable resistance nonvolatile memory device according to claim 10, wherein:
in the first verify operation, the read resistance value is determined not to satisfy the first determination condition when the read resistance value is lower than a third threshold value,
in the second verify operation, the read resistance value is determined not to satisfy the second determination condition when the read resistance value is lower than a fourth threshold value, and
the fourth threshold value is lower than the third threshold value.
13. The variable resistance nonvolatile memory device according to claim 11, wherein:
the initial voltage pulse is for changing the variable resistance element from a first resistance state to a second resistance state having a lower resistance value than the first resistance state does, and
the second threshold value is lower than a reading reference resistance value that is a reading criterion for determining whether the variable resistance element is in the first resistance state or the second resistance state.
14. The variable resistance nonvolatile memory device according to claim 12, wherein:
the initial voltage pulse is for changing the variable resistance element from a second resistance state to a first resistance state having a higher resistance value than the second resistance state does, and
the fourth threshold value is higher than a reading reference resistance value that is a criterion for determining whether the variable resistance element is the first resistance state or the second resistance state.
15. The variable resistance nonvolatile memory device according to claim 10, wherein the voltage pulse is different from the initial voltage pulse in a voltage value or a pulse width.
16. The variable resistance nonvolatile memory device according to claim 10, wherein the voltage pulse is same as the initial voltage pulse in a voltage value and a pulse width.
17. The variable resistance nonvolatile memory device according to claim 10, wherein the second verify operation further includes (E) stopping the performance of the second verify operation when a number of times of the second verify operation reaches a predetermined upper limit.
18. The variable resistance nonvolatile memory device according to claim 17, wherein the pulse application circuitry is further operative to: (F) perform a third verify operation at least once after the number of times of the second verify operation reaches the predetermined upper limit, the third verify operation including (f1) reading the resistance value of the variable resistance element, (f2) determining whether or not the read resistance value satisfies the first determination condition, and (f3) applying a voltage pulse to the variable resistance element when the read resistance value does not satisfy the first determination condition.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. An image forming apparatus having a printing function to discharge a printed material acquired by recording image data included in a printing job received through a network on a recording paper and a scanner function to acquire the image data by reading a manuscript image, comprising:
a first discharge tray provided in a discharge space in a body of the apparatus;
a second discharge tray other than the first discharge tray;
a long-time use judging unit judging whether the scanner function is in use for a long time; and
a discharge destination selecting unit,
wherein the discharge destination selecting unit
discharges the printed material to the first discharge tray when the long-time use judging unit judges that the scanner function is not in use for a long time at the time of receiving the printing job, and
discharges the printed material to the second discharge tray when the long-time use judging unit judges that the scanner function is in use for a long time at the time of receiving the printing job.
2. The image forming apparatus according to claim 1, wherein:
the long-time use judging unit judges that the scanner function is in use for a long time when a scanner operation is continuously performed for a reference use time while the scanner function is commanded.
3. The image forming apparatus according to claim 1, wherein:
the long-time use judging unit judges that the scanner function is in use for a long time when switching to the scanner function is repeatedly performed within a reference standby time.
4. The image forming apparatus according to claim 1, further comprising:
a slot unit connected with an external memory,
wherein the long-time use judging unit judges that the scanner function is in use for a long time when the external memory is connected to the slot unit over a predetermined time.