1. Field of the Invention
The invention relates to an image forming apparatus such as, for example, a copying machine, a facsimile apparatus or a printer of an electrophotographic printing type, and an image forming apparatus administration system.
2. Related Background Art
In offices, there are handled many office automation (GA) apparatuses including image forming apparatuses such as, for example, copying machines and facsimile apparatuses.
An image forming apparatus has replaceable parts such as an image bearing member such as an electrophotographic photosensitive member, a developer, a sheet feeding roller and a fixing roller and therefore, after the use thereof for a predetermined period, it is necessary to replace these parts. However, the timing for replacing the parts differs greatly depending on a user s use condition such as, for example, the use environment, the kind of transfer paper, the number of used sheets per day, or the image percentage of an image. Further, there is also the irregularity of the qualities of the replaceable parts.
Accordingly, when only a lifetime shorter than estimated is reached, the image forming apparatus is stopped and there occurs a time during which the user cannot use the apparatus, and this leads to the possibility that the operable time of the image forming apparatus may be reduced.
In recent years, the higher efficiency of work has been advanced and importance has been attached to the operable time of the image forming apparatus and particularly, in an image forming apparatus of a high speed (100 ppm or greater), there has been required such high productivity that the apparatus does not stop for 10 hours on end.
To solve this problem, there are proposed various techniques at present.
In Japanese Patent Application Laid-open No. 2001-117295, at a position downstream of the opposed position of a photosensitive drum to a developing sleeve with respect to the rotation direction thereof, a developer in a developing device is made replaceable with a fresh developer so that a detected potential may be maintained at a set potential in accordance with the surface potential of the photosensitive drum detected by a potential sensor.
Accordingly, the degree of deterioration of the developer is judged, and in accordance with the degree of deterioration, the developer in a developer container is automatically replaced with a fresh developer, whereby images of high quality can be stably provided for a long period. Further, it is possible to greatly curtail running costs.
As the task of long lifetime development to be studied, there have been done the development of a developer extended in endurance lifetime and the development of a process which does not deteriorate the developer, and the lifetime of the developer at present is 30,000 to 50,000 sheets. A counter method which is a method whereby a serviceman periodically replaces the developer in accordance with a predetermined number of endurance test sheets is generally carried out to thereby enhance the rate of operation of the image forming apparatus.
Further, there is a technique of detecting the quantity of reflected light when a relatively large spotlight (having a spot diameter of several millimeters or greater) is applied to a patch pattern formed on an image bearing member (hereinafter referred to as the “patch detecting method”), thereby detecting the amount of toner adhering to the patch pattern. A technique of controlling image forming conditions such as an electrostatic latent image condition and a developing condition in accordance with the result of the detection of the afore-mentioned amount of toner is applied to actual commodities.
By detecting the amount of adhering toner on each density patch of a gradation pattern, it is possible to know harmony and solid density under the image forming conditions. Therefore, if the values of these depart from a prescribed range, the control of the image forming conditions is effected so as to obtain appropriate harmony in accordance with the result, and to provide appropriate solid density, and the harmony and the solid density can be modified. The controlled image forming conditions include the toner density of the developer (in the case of a dual-component developing process), a development bias, the speed of a developer carrying member, etc.
The deteriorated state of the developer is detected by the above-described patch detecting method to thereby control the developing conditions, extend the lifetime of the image forming apparatus and increase the operating time thereof.
Also, in Japanese Patent Application Laid-open No. H05-289494, the toner density of a developer in a developing device is detected, and when the fluctuation of an image due to the fluctuation of the toner density with time occurs, the development gap is suitably adjusted to thereby increase the operating time of an image forming apparatus.
In Japanese Patent Application Laid-open No. H08-314815, there is proposed an administration system for an image forming apparatus in which the image forming apparatus and a host computer in a business office taking charge of the maintenance or the like of the image forming apparatus are connected together by communicating means, and data such as count information transmitted from the image forming apparatus is received by a host computer, and the received data is analyzed and displayed on the host computer side.
For example, such an administration system for the image forming apparatus is designed such that the amount of toner consumed in the image forming apparatus is monitored on the host computer side, and when the toner in a toner supplying container for supplying the toner to developing means has become exhausted, and when it is detected that a toner collecting container for storing therein the toner collected from a photosensitive member has become full of the toner, a serviceman is instructed to replace the toner supplying container and the toner collecting container. As a result, such a situation can be coped with at real time in accordance with the state of the image forming apparatus to thereby enhance the operable time.
In Japanese Patent Application Laid-open No. 2001-296706, developing capability is synthetically inferred from the information of the operable time of a developing apparatus, toner density, the amount of consumed toner, etc., and one of the latent image forming condition, the toner supplying condition, etc. is selected and controlled to thereby cope with all changes with time, thus prolonging the operable time of an image forming apparatus.
Also, in Japanese Patent Application Laid-open No. H11-15338, the degree of deterioration of a developer is presumed from the density on a photosensitive member, load torque applied to a developing device and the permeability of a toner in a developer container, and the developing condition is changed to thereby extend the lifetime of the developer.
There are various disadvantages in the examples of the conventional methods described above.
a) In the potential sensor method of detecting the amount of toner on the photosensitive member described above, the state of the developer after already being deteriorated is detected, and this leads to the disadvantage that it is difficult to measure the degree of deterioration of the developer accurately and it is impossible to estimate the lifetime at the beginning to the middle of the operation.
b) In the judgment of the deterioration of the developer by the counter detecting method described above, the estimated accuracy of the lifetime of the developer is low and therefore, the user effected the use greatly exceeding the lifetime of the developer, and this leads to the fear that an image defect or the scattering of the developer in the machine may occur. There is also the disadvantage that the developer which is still usable is replaced.
c) In the patch detecting method described above, the developing state can be grasped, but there is the disadvantage that detection can be effected only after the developer has been deteriorated, and this limits taking countermeasures.
d) In the development gap adjusting method described above, it is impossible to detect beforehand how much the developer has been deteriorated, and it is necessary to provide a mechanism for adjusting, and this leads to the disadvantage that much expense is required.
e) In the detecting method by the host computer described above, only the amount of remaining toner is detected and reported to a server. However, the deterioration of the quality of image itself is not detected and therefore, the effect of curtailing the operating time by the user is low.
f) In the method of coping with the changes with time on the basis of multi-dimensional information, the other conditions are changed in an already deteriorated state and therefore, a change suddenly happening cannot be coped with, and there is the undesirable possibility that the operating time may be reduced.
g) In the method of presuming the deterioration of the developer from the load torque and the permeability, detection is effected in the state after already being deteriorated, and this leads to the undesirable possibility that the replacement timing of the developer may shift.
Against the above-noted disadvantages, it is ideally necessary that the developer, the photosensitive member, etc. be necessarily replaced when a certain operating time during which the quality of image is anticipated to be deteriorated at a development stage has been reached. However, as described above, means for the detection of the quality of image and the detection of the deterioration of each part concerned with the quality of image at present cope with only the procedure after deterioration or the transition of deterioration and therefore, are very low in reliability. Therefore, it is the present situation that the replacement time is unavoidably set short in view of the safety rate. Further, it is known that actually the operating conditions differ from one user to another and in conformity therewith, the replacement time of the developer, the photosensitive member, etc. which can ensure the quality of image differs greatly.
When the deterioration of the quality of image and the deterioration of the parts are detected beforehand and the deterioration has been confirmed, appropriately coping with maintenance will lead to the higher work efficiency of the maintenance, and an increase in the operable time of the image forming apparatus. For that purpose, the tolerance (hereinafter referred to as the “latitude”) of a part itself to the deterioration of an image must be detected before the part reaches the end of its lifetime.