Patent Number: 
Section: claims

1. A maintenance system adapted for making a maintenance plan for consumable parts of an apparatus that is a maintenance target, comprising:an interval information acquiring unit configured to acquire information related to a combination of a visit interval that prescribes a time interval at which a visit should be made for maintenance operation for each consumable part, and a replacement interval, associated with the visit interval, that prescribes a time interval at which each consumable part should be replaced;a counter value acquiring unit configured to acquire a counter value that indicates actual use of consumable parts in the apparatus; anda maintenance plan calculating unit configured to calculate timing at which a next visit should be made for the apparatus, and a consumable part that should be replaced at the timing, on the basis of the information acquired by the interval information acquiring unit and the counter value acquired by the counter value acquiring unit. 2. The maintenance system according to claim 1, wherein the consumable parts include a cartridge in which plural consumable parts having different functions from each other are formed integrally as a unit. 3. The maintenance system according to claim 1, comprising:a replacement difficulty judging unit configured to judge whether or not the consumable part that should be replaced, calculated by the maintenance plan calculating unit, is a component that can only be replaced by a serviceman carrying out maintenance operation for the apparatus; anda notifying unit configured to, if the replacement difficulty judging unit judges that the consumable part is a component that can only be replaced by the serviceman, issue a notification that a visit should be made for the apparatus in order to replace the component. 4. The maintenance system according to claim 1, comprising:a visit interval calculating unit configured to calculate the visit interval for each consumable part on the basis of failure rate distribution of each consumable part;a replacement interval calculating unit configured to calculate the replacement interval for each consumable part on the basis of failure rate distribution of each consumable part; anda combination calculating unit configured to calculate information related to a combination of a time interval at which a visit should be made for maintenance operation and a consumable part that should be replaced at the timing, on the basis of the visit interval calculated by the visit interval calculating unit and the replacement interval calculated by the replacement interval calculating unit;wherein the interval information acquiring unit acquires the information calculated by the combination calculating unit. 5. The maintenance system according to claim 4, wherein the visit interval calculating unit randomly calculates the visit interval, and the replacement interval calculating unit randomly calculates the replacement interval, andthe combination calculating unit finds a combination of a visit interval and a replacement interval that minimizes a predetermined cost, on the basis of the visit interval calculated by the visit interval calculating unit and the replacement interval calculated by the replacement interval calculating unit. 6. The maintenance system according to claim 5, wherein the visit interval calculated for each consumable part by the visit interval calculating unit is set to be longer than the replacement interval calculated by the replacement interval calculating unit. 7. The maintenance system according to claim 5, wherein the predetermined cost is a sum of labor cost required for maintenance operation by a serviceman, material cost of consumable parts, and amount of loss caused by unavailability of the apparatus that is the maintenance target to a user. 8. The maintenance system according to claim 5, wherein the combination calculating unit performs search processing using a Monte Carlo method or a genetic algorithm on the basis of the visit interval calculated by the visit interval calculating unit and the replacement interval calculated by the replacement interval calculating unit, thereby finding a combination of a visit interval and a replacement interval that minimizes the predetermined cost. 9. The maintenance system according to claim 5, wherein the visit interval calculating unit and the replacement interval calculating unit calculate, on the basis of failure probability distribution of each consumable part, a value close to an interval with which the failure probability is predicted to be equal to or higher than a predetermined probability. 10. A maintenance system for making a maintenance plan for consumable parts of an apparatus that is a maintenance target, comprising:interval information acquiring means for acquiring information related to a combination of a visit interval that prescribes a time interval at which a visit should be made for maintenance operation for each consumable part, and a replacement interval, associated with the visit interval, that prescribes a time interval at which each consumable parts should be replaced;counter value acquiring means for acquiring a counter value that indicates actual use of consumable parts in the apparatus; andmaintenance plan calculating means for calculating timing at which a next visit should be made for the apparatus, and a consumable part that should be replaced at the timing, on the basis of the information acquired by the interval information acquiring means and the counter value acquired by the counter value acquiring means. 11. The maintenance system according to claim 10, comprising:replacement difficulty judging means for judging whether or not the consumable part that should be replaced, calculated by the maintenance plan calculating means, is a component that can only be replaced by a serviceman carrying out maintenance operation for the apparatus; andnotifying means for, if the replacement difficulty judging means judges that the consumable part is a component that can only be replaced by the serviceman, issuing a notification that a visit should be made for the apparatus in order to replace the component. 12. A maintenance method adapted for making a maintenance plan for consumable parts of an apparatus that is a maintenance target, comprising:acquiring information related to a combination of a visit interval that prescribes a time interval at which a visit should be made for maintenance operation for each consumable part, and a replacement interval, associated with the visit interval, that prescribes a time interval at which each consumable parts should be replaced;acquiring a counter value that indicates actual use of consumable parts in the apparatus; andcalculating using a CPU, timing at which a next visit should be made for the apparatus, and a consumable part that should be replaced at the timing, on the basis of the acquired information related to the combination of the visit interval and the replacement interval, and the acquired counter value. 13. The maintenance method according to claim 12, wherein the consumable parts include a cartridge in which plural consumable parts having different functions from each other are formed integrally as a unit. 14. The maintenance method according to claim 12, comprising:judging whether or not the consumable part that should be replaced is a component that can only be replaced by a serviceman carrying out maintenance operation for the apparatus; andif the consumable part is judged to be a component that can only be replaced by the serviceman, issuing a notification that a visit should be made for the apparatus in order to replace the component. 15. The maintenance method according to claim 12, comprising:calculating the visit interval for each consumable part on the basis of failure rate distribution of each consumable part;calculating the replacement interval for each consumable part on the basis of failure rate distribution of each consumable part; andcalculating the information related to the combination of the time interval and the replacement interval, on the basis of the visit interval as calculated and the replacement interval as calculated. 16. The maintenance method according to claim 15, wherein the visit interval is randomly calculated, and the replacement interval is randomly calculated, andthe combination of the visit interval and the replacement interval that minimizes a predetermined cost is found, on the basis of the visit interval as calculated and the replacement interval as calculated. 17. The maintenance method according to claim 16, wherein the visit interval calculated for each consumable part is set to be longer than the replacement interval. 18. The maintenance method according to claim 16, wherein the predetermined cost is a sum of labor cost required for maintenance operation by a serviceman, material cost of consumable parts, and amount of loss caused by unavailability of the apparatus that is the maintenance target to a user. 19. The maintenance method according to claim 16, wherein the combination of the visit interval and the replacement interval that minimizes the predetermined cost is found using a Monte Carlo method or a genetic algorithm on the basis of the visit interval as calculated and the replacement interval as calculated. 20. The maintenance method according to claim 16, wherein the visit interval and the replacement interval are each calculated on the basis of failure probability distribution of each consumable part and to have a value close to an interval with which the failure probability is predicted to be equal to or higher than a predetermined probability.