1. A charging device comprising:
a discharge electrode that extends along an axial direction of a member to be charged, the member to be charged having a cylindrical shape or a columnar shape; and
a potential control plate that is disposed between the member to be charged and the discharge electrode and curved along a peripheral surface of the member to be charged,
wherein the potential control plate includes
three or more structural lines that are arranged in a circumferential direction of the member to be charged and that linearly extend along the axial direction of the member to be charged, and
a plurality of connecting portions that are arranged in the axial direction of the member to be charged, each connecting portion connecting two or more of the three or more structural lines to each other, the two or more structural lines being next to each other in the circumferential direction of the member to be charged,
wherein the structural lines connected by one of the plurality of connecting portions and the structural lines connected by another one of the plurality of connecting portions are at least partly different from each other.
2. The charging device according to claim 1, wherein each of the plurality of connecting portions connects only two of the three or more structural lines to each other, the two structural lines being next to each other in the circumferential direction of the member to be charged.
3. The charging device according to claim 1, wherein all of the structural lines connected by one of the plurality of connecting portions and the structural lines connected by another one of the plurality of connecting portions that is next to the one of the plurality of connecting portions in the axial direction of the member to be charged are different from each other.
4. The charging device according to claim 1, wherein, of the plurality of connecting portions, connecting portions that are next to each other in the axial direction of the member to be charged are arranged at a constant pitch in the circumferential direction of the member to be charged.
5. The charging device according to claim 1, wherein the potential control plate is elastically deformed so as to be curved along the peripheral surface of the member to be charged by a force applied to both end portions of the potential control plate in the axial direction of the member to be charged, and
wherein the plurality of connecting portions are arranged at a lower density at a central area of the potential control plate than at both ends of the potential control plate in the axial direction of the member to be charged.
6. The charging device according to claim 1, further comprising:
a cleaning member that cleans the potential control plate,
wherein the plurality of connecting portions are at an angle of substantially 20 degrees or more with respect to the structural lines.
7. The charging device according to claim 1, wherein the potential control plate is flat plate shaped when the potential control plate is not attached to the charging device, and is curved by a tension applying member and curve regulating members when the potential control plate is attached to the charging device, the tension applying member applying a tension to the potential control plate in the axial direction of the member to be charged, and the curve regulating members being provided at both ends of the potential control plate in the axial direction of the member to be charged.
8. The charging device according to claim 7, wherein the potential control plate maintains the curved shape by being interposed between the curve regulating members and curve maintaining members that face the curve regulating members.
9. An image forming apparatus comprising:
the charging device according to claim 1 and a photoconductor,
the photoconductor being the member to be charged, and the photoconductor being charged by the charging device and having an overcoat layer.
10. A potential control plate comprising:
three or more structural lines that are arranged in a circumferential direction of a member to be charged and that linearly extend along an axial direction of the member to be charged, and
a plurality of connecting portions that are arranged in the axial direction of the member to be charged, each connecting portion connecting two or more of the three or more structural lines to each other, the two or more structural lines being next to each other in the circumferential direction of the member to be charged,
wherein the structural lines connected by one of the plurality of connecting portions and the structural lines connected by another one of the plurality of connecting portions are at least partly different from each other.
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. A method of derivation, by an electronic circuit, of a first key from a second key, wherein:
at least one third key is derived from the second key and is used to derive the first key;
a value of a counter, representative of the number of first keys, conditions the derivation of a new value of the third key.
2. The method of claim 1, wherein a first most significant portion of the counter represents the number of uses of the second key.
3. The method of claim 2, wherein a first least significant portion of the counter represents the number of uses of the third key.
4. The method of claim 2, wherein at least one bit of the first portion of the counter is duplicated.
5. The method of claim 4, wherein the entire first portion of the counter is duplicated.
6. The method of claim 4, wherein the duplicated value is stored in a non-volatile memory.
7. The method of claim 1, wherein a new value of the third key is generated when the value of the counter reaches a threshold.
8. The method of claim 2, wherein a new value of the third key is generated when the least significant bit of the first portion of the counter differs from the duplicated value.
9. The method of claim 1, wherein several third keys are used by being derived from one another.
10. The method of claim 1, wherein the counter is stored in a non-volatile memory.
11. The method of claim 1, wherein at least the second and third keys are stored in a non-volatile memory.
12. An electronic circuit capable of implementing the method of claim 1.