1. Field of the Invention
The present invention relates to an image forming system that includes an image forming apparatus mounted with a plurality of components and a lifetime management device that manages information on the lifetime of the components.
2. Description of the Related Art
When a failure occurs in a part of an image forming apparatus such as a copier, a facsimile machine, and a printer, depending on the type of the part, the image forming apparatus cannot be used until the part is replaced by a new one, and this imposes inconvenience on a user.
Therefore, various types of image forming systems have been proposed, which estimate the end of the service life of respective parts or components of an image forming apparatus to issue a request to replace a part which reaches its service life. For example, Japanese Patent Application Laid-open No. H9-146423 discloses such an image forming system. In the conventional image forming system, the number of prints produced by an image forming apparatus is calculated with respect to each of parts mounted thereon. When the number of prints exceeds a predetermined threshold for one of the parts, it is determined that the part has deteriorated to about the end of its service life due to printing operation. Then, a signal is transmitted to a remote monitoring device to request replacement of the part. In response to the request, a replacement worker, such as a service person, replaces the part before a failure occurs, which reduces the downtime of the image forming apparatus.
Some of the various parts mounted on the image forming apparatus deteriorate depending on an operation amount specific to the parts rather than the number of prints. For example, a developing roller, which does not closely contact recording paper during the printing operation, deteriorates depending on the operation amount including the total rotation time and the total rotation distance rather than the number of prints (hereinafter, this type of part is referred to as “operation amount-dependent deteriorated part”). On the other hand, a cleaning member that removes paper dust from the recording paper and toner remaining on an intermediate transfer belt, and a fixing roller that strongly contacts the recording paper deteriorates depending on the number of prints rather than the operation amount (hereinafter, this type of part is referred to as “print volume-dependent deteriorated part”). If the number of prints is completely proportional to the operation amount, the end of service life of each part can be accurately estimated based on the number of prints. However, the number of prints and the operation amount do not show a proportional correlation.
A factor of this relates to an idle operation at the start and the end of a print job. Specifically, the printing operation of the image forming apparatus includes a single printing operation in which an image is formed only on one recording sheet, and a continuous printing operation in which images are continuously formed on a plurality of recording sheets. In either printing operation, an idle operation, in which a sheet is not fed to respective parts, is performed when a job starts and ends. The idle operation is performed for the same time period in the single printing operation and the continuous printing operation. Accordingly, in the single printing operation, the percentage of the idle operation time in the total operation time is high compared to the continuous printing operation. Further, in the continuous printing operation, as the number of continuous prints decreases, the percentage of the idle operation time increases. Therefore, when a user frequently performs single printing and rarely performs continuous printing of relatively a few copies, the operation amount is considerably large, while the number of prints is relatively small. In such a case, if the service life is estimated based only on the number of prints, the operation amount-dependent deteriorated part may reach the end of its service life before the estimated one. On the contrary, when a user performs continuous printing of a large number of copies frequently and single printing relatively infrequently, the operation amount is considerably small, while the number of prints is relatively large. In such a case, if the service life is estimated based only on the number of prints, it is likely to be determined that the operation amount-dependent deteriorated part is almost at the end of its service life even if sufficient time remains until the end.
Therefore, the present inventors have studied to estimate service life based on the operation record of each part, instead of the number of prints, for the operation amount-dependent deteriorated parts. However, the number of prints more or less relates to the progress of deterioration even in the operation amount-dependent deteriorated parts according to the type of recording paper. Specifically, paper dust can adhere to the operation amount-dependent deteriorated parts such as the developing roller, which does not closely contact recording paper, via the intermediate transfer belt and a photosensitive drum, which closely contact recording paper. When a user mainly uses recording paper likely to generate paper dust, such as low-quality paper, the amount of adhering dust considerably increases. As a result, the number of prints relates relatively closely to the progress of deterioration even in the operation amount-dependent deteriorated parts. In such a case, if the service life of the operation amount-dependent deteriorated part is estimated based only on the operation record, estimation accuracy decreases.