Image forming apparatus having apparatus main assembly and a process cartridge including non-contact memory performing non-contact data communication with the apparatus main assembly

An image forming apparatus includes an apparatus main assembly, and a process cartridge detachably mountable to the apparatus main assembly, including a driving force receiver to be connected to a driver of the apparatus main assembly and a non-contact memory for carrying out non-contact data communication with a receiver of the apparatus main assembly, wherein the apparatus main assembly performs rotational driving of the driver before reading out data from the non-contact memory.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an image forming apparatus including a process cartridge which is detachably mountable to a main assembly of the image forming apparatus, particularly an image forming apparatus which permits data communication between a non-contact memory mounted process cartridge and the apparatus main assembly.

2. Background Art

For example, in an ordinary image forming apparatus, such as a copying machine, a printer or the like, a load unit constituting a part of an image forming means, such as a photosensitive drum or an intermediary transfer belt, is rotationally driven by transmitting thereto a driving force (power) through a coupling or connection mechanism disposed between such a load unit and a driving source of the main assembly of the image forming apparatus. Such a load unit reaches the end of its life due to wear and/or deterioration with time. The life of the load unit is shorter than that of the image forming apparatus main assembly, so that there is a need for the load unit to be replaced with a new one on several occasions until the image forming apparatus main assembly reaches the end of its life. For this reason, the load unit is used in the form of a cartridge in view of the ease in mounting and dismounting the cartridge in many cases.

In recent years, a memory has been provided in the cartridge so as to have the following functions (1), (2) and (3):

(1) in the memory, data, such as initial characteristics of the unit at the time of the production thereof, identifying (discriminating) information thereof, or the like is stored, and the data is used for switching control specifications for the photosensitive drum, or the like in the cartridge;

(2) in the memory, data on an operation time of the unit is stored and used for judging the unit's replacement timing; and

(3) in the memory, the same fluctuation values vary, depending on durability factors of the unit, and optimum image formation is performed on the basis of the most up-to-date values.

As a result, the memory is utilized for improving image qualities of the image forming apparatus.

As the memory for such a purpose, a non-contact memory is used in many cases, since it has the advantages of, e.g., high reliability of point of contact attributable to high resistance to mounting/dismounting operations and a simple circuit structure. This is because, the non-contact memory carries out communication with the apparatus main assembly by transmission and reception of electromagnetic waves between antennas provided in both the apparatus main assembly and the memory, so that the non-contact memory does not need any contact between metal terminals as in a conventional memory, thus causing no problems arising from the required contact of terminals, such as noise, toner contamination, various vibrations, or the like.

With respect to the access procedure of the image forming apparatus to the non-contact memory provided in the memory as described above, Japanese Laid-Open Patent Application (JP-A) 2002-149039 has proposed that a state of means for transmitting electromagnetic waves to the non-contact memory is switched on the basis of a detection result determining whether a door is opened or closed, the door permitting a detachably mountable load unit to be mounted to and dismounted from an apparatus main assembly. In other words, when the door is opened, communication is stopped since there is a possibility that the load unit is removed, and on the other hand, when the door is closed, the communication is started since there is a possibility that the load unit is mounted.

However, in the case where the load unit is mounted at the time when the door is closed, the state in which communication is permitted with reliability is not necessarily optimal. When a user mounts the load unit into the apparatus main assembly by opening the door, it is by no means easy to mount the load unit at a predetermined position accurately at the time of image formation. This is because a drive portion of the load unit to be connected to the apparatus main assembly is required to be positioned with a high degree of accuracy. In other words, the allowance for positional deviation from the optimal position is very small.

On the other hand, a structure has been employed in which the apparatus main assembly is automatically moved to a predetermined position at the time of image formation by transmitting a driving force to the load unit in an image-forming operation so as to obviate the necessity for the user to take the trouble to accurately mount the load unit. Accordingly, somewhat of a positional deviation of the load unit with respect to the apparatus main assembly occurs immediately after the door is closed. As a result, an antenna on the load-unit side is not necessarily located in an ideal position.

To accommodate such positional deviation, the receiving sensitivity or the sending power of the antenna is increased in order to permit reliable communication before carrying out necessary operations for image formation. However, in this case, size reduction of the load unit becomes difficult, and there arises a possibility that an increase in sending powder causes interference with an antenna with which it is not intended to communicate or leakage of electromagnetic waves to the outside of the image forming apparatus in some cases. For this reason, in view of measures that can be taken against these problems, it cannot be said that communication is ensured even when the position of the load unit is somewhat deviated from the predetermined position.

SUMMARY OF THE INVENTION

An object of the present invention is to provide an image forming apparatus capable of providing a high stability in communication between a non-contact memory of a process cartridge and an apparatus main assembly.

According to the present invention, there is provided an image forming apparatus, comprising:

an apparatus main assembly, and

a process cartridge detachably mountable to the apparatus main assembly, including driving force receiving means to be connected to driving means of the apparatus main assembly and a non-contact memory for non-contact data communication with receiving means of the apparatus main assembly,

wherein the apparatus main assembly performs rotational driving of the driving means before reading out data from the non-contact memory.

DESCRIPTION OF PREFERRED EMBODIMENTS

Hereinbelow, embodiments of the image forming apparatus according to the present invention will be described with reference to the drawings. In the drawings, identical reference numerals or symbols represent identical members or functions, and repeated explanations therefor are omitted as desired.

FIG. 1is a cross-sectional view showing a four-color-based full-color printer as an embodiment of the image forming apparatus of the present invention.

Referring toFIG. 1, a printer (hereinafter, referred to as the “image apparatus”) includes an image forming apparatus main assembly1which roughly includes four image-forming stations disposed in parallel with each other, a paper supply means, an intermediary transfer means, a conveyance means, a fixing unit, an operation means, and control means (not shown). The respective image-forming stations have the same structure.

More specifically, the image-forming stations include drum-type electrophotographic photosensitive members (hereinafter, referred to as the “photosensitive drum(s)”)11a,11b,11cand11d,functioning as image bearing members. Each of the photosensitive drums11ato11dis supported by a central axis (shaft) and rotationally driven in a direction of an arrow shown inFIG. 1inside the drums by a stepping motor and for each of the photosensitive drums11ato11dcouplings for transmitting a rotational force are used.

The structure of the couplings will be described with reference toFIGS. 2-5, whereinFIG. 2is a front view of the coupling on the photosensitive-drum side,FIG. 3is a corresponding perspective view,FIG. 4is a perspective view of the coupling on the stepping-motor side, andFIG. 5is a view showing a state in which the couplings on the photosensitive-drum side and the stepping-motor side are disposed opposite to and to be connected with each other.

A coupling19(19a,19b,19cand19d) is constituted by engaging a coupling191on the photosensitive-drum side and a coupling192on the stepping-motor side.

The coupling191on the photosensitive-drum side is formed in such a shape that a triangular pole191ais twisted as shown inFIGS. 2 and 3, and on the other hand, the coupling192on the stepping-motor side is provided with a triangular hole192afor engaging the twisted triangular pole191atherein. These couplings191and192are used in combination, as shown inFIG. 5, so that the twisted triangular pole191aof the coupling191on the photosensitive-drum side is disposed opposite to the triangular hole192aof the coupling192on the stepping-motor side to engage the triangular pole191awith the triangular hole192ato connect both couplings191and192to each other. As a result, a driving force of the stepping motor can be transmitted to the photosensitive drums (11a,11b,11cand11d) through the coupling19.

Incidentally, in the case where the position of the triangular hole192aof the coupling192is not in alignment with the position of the triangular pole191aof the coupling191when the photosensitive drums11ato11dare set, the photosensitive drums11ato11dare accommodated in the image forming apparatus main assembly1by compression of a spring20shown in FIG.5. Thereafter, the triangular hole192aof the coupling192on the stepping-motor side is rotated when the stepping motor is rotated, whereby the triangular pole191aof the coupling191on the photosensitive-drum side is engaged in the triangular hole192aof the coupling192on the stepping-motor side (at this time the spring20expands) at a timing of positional alignment of the triangular hole192awith the triangular pole191aof the coupling191on the photosensitive-drum side. As a result, the driving force of the stepping motor is transmitted to the photosensitive drums11ato11d.

The size of the triangular hole192aof the coupling192on the stepping-motor side is designed to be somewhat larger than that of the triangular pole191aof the coupling191on the photosensitive-drum side, and the triangular pole191aand the triangular hole192aare twisted. As a result, when the coupling191shown inFIG. 2is rotated clockwise, a force acts in such a direction that the engaging triangular pole191ais pulled into the triangular hole192a,whereby a connection or coupling portion between the stepping motor and the photosensitive drums (11ato11d) is locked.

On the other hand, when the coupling191is rotated counterclockwise, a force acts in such a direction that the triangular pole191ais pushed out of the triangular hole192a,so that the connection (coupling) between the stepping motor and the photosensitive drum is released. However, when the coupling191is rotated slightly counterclockwise in the connection state, it is possible to cause the photosensitive drums11ato11dto remain stationary, although the locked connection is released by the clearance created due to a difference in size between the triangular pole191aand the triangular hole192a.

Based on such a structure of the coupling19(191,192), the coupling191has such a property that it is locked to retain the connection state when the photosensitive drums11a-11dare rotationally driven in the direction of the arrows inside drums11ato11dshown inFIG. 1(in the ordinary rotational direction) at the time of image formation by normal rotation of the stepping motor. On the other hand, the coupling191also has such a property that the lock is released to release the connection state when the stepping motor is (reversely) rotated in the direction opposite from the direction of the arrows inside drums11ato11dshown in FIG.1.

The charge rollers12ato12dimpart electrical charges with a uniform amount of charge to the surfaces of the photosensitive drums11ato11d,respectively, to uniformly electrically charge the photosensitive drums11ato11d,respectively, to a predetermined polarity and a predetermined potential.

The photosensitive drums11ato11dafter the charging process are irradiated with a light beam, such as a laser beam, which has been modulated depending on picture (image) information. As a result, on the photosensitive drums11ato11d,electrical charges at their irradiation portion are removed to form electrostatic images.

The electrostatic images are visualized (developed) as (color) toner images by the developing apparatuses14a,14b,14cand14dcontaining therein developers (toners) of yellow, cyan, magenta and black, respectively. The developed toner images are successively transferred onto an intermediary transfer belt30.

Through the above-mentioned processes, image-forming operations with the respective color toners are successively performed. At the time of image formation, various values as to the image-forming operations are stored in a memory (not shown).

The paper-supply means includes a portion for accommodating a recording material P (e.g., paper or a transparent film), a roller for conveying the recording material P, a sensor for detecting passing of the recording material P, a sensor for detecting the presence/absence of the recording material P, and a guide (not shown) for conveying the recording material P along a conveyance passage.

InFIG. 1, the apparatus main assembly1includes paper-feed cassettes21a,21b,21cand21d;a manual-feed tray27; and a paper-feed deck28. In these members, the recording material P is held. The apparatus main assembly1further includes pickup rollers22a,22b,22cand22dfor feeding the recording material P one by one from the paper-feed cassettes21ato21d,respectively. These pickup rollers22ato22dfeed a plurality of sheets of the recording material P in some cases, but only one sheet is separated with reliability from the fed sheets of the transfer material by BC rollers23a,23b,23cand23d,respectively.

The thus-separated sheet is conveyed to registration rollers25through drawing rollers24a,24b,24cand24d,and preliminary registration rollers26. The recording material P held in the manual-feed tray27is separated one by one by a BC roller29and conveyed to the registration rollers25through the preliminary registration rollers26. Further, a plurality of sheets of the recording material P held in the paper-feed deck28are fed to a paper-feed roller61through a pickup roller60and are separated one by one by the paper-feed roller61with reliability, thus being carried to the registration rollers25.

An intermediary transfer unit (load apparatus) U will now be described.

The intermediary transfer unit U includes the intermediary transfer belt30as the intermediary transfer member. As a material for the intermediary transfer belt30, for example, PET (polyethylene terephthalate), PVDF (polyvinylidene difluoride), or the like are used. The intermediary transfer belt30is extended around a drive roller32, a tension roller33and a secondary transfer opposite roller34.

The drive roller32is a roller for transmitting a driving force to the intermediary transfer belt30and rotationally drives the intermediary transfer belt30in a clockwise direction. The tension roller33is a roller for exerting an appropriate tension on the intermediary transfer belt30under the action of a pressing force of a spring (not shown). The secondary transfer opposite roller34and a secondary transfer roller36sandwich therebetween the intermediary transfer belt30so as to create a secondary transfer nip (secondary transfer station) therebetween.

The drive roller32is prepared by coating the surface of a metal roller with a several mm-thick layer of rubber (composed of urethane or chloroprene), thus preventing slipping with the intermediary transfer belt30. The drive roller32is rotated by transmitting a rotating force thereto from the secondary transfer for rotationally driving the photosensitive drums11ato11dand is also provided with a coupling (not shown) as a transmission means. This coupling is also locked when the photosensitive drums11ato11dare rotated in the direction of the arrow inside drums11ato11dshown inFIG. 1similarly as in the couplings19used for the photosensitive drums11ato11d,and is designed to release the lock by being rotated in a direction opposite to the direction of the arrow inside the drums11ato11dshown in FIG.1.

On the backside of the intermediary transfer belt30at positions where the photosensitive drums11ato11dare disposed, primary transfer rollers35a,35b,35cand35d,to which a high voltage for transferring the toner image onto the intermediary transfer belt30is applied, are disposed, respectively.

A secondary transfer roller36is pressed against the intermediary transfer belt30under an appropriate pressure. Downstream from the secondary transfer roller36along the rotational direction of the intermediary transfer belt30, a cleaning apparatus50for cleaning the surface (onto which the toner image is transferred) of the intermediary transfer belt30is disposed. The cleaning apparatus50includes a cleaner blade51(composed of, e.g., an urethane rubber) and a waste-toner box52for containing therein waste toner.

A fixing unit40includes a fixing roller41acontaining therein a heat source, such as a halogen heater or the like, a pressure roller41b,which is pressed against the fixing roller41aand optionally provided with a heat source, and an inner paper-output roller44for conveying the recording material P that has been discharged from these fixing and pressure rollers41aand41b.

On the other hand, the recording material P conveyed to the registration rollers25is once stopped by terminating the rotational drive of the upstream rollers, and then the upstream rollers and the registration rollers25are rotationally driven again at a timing of image formation at the image-forming station. The recording material P is sent to a stationary transfer nip, where the toner images on the intermediary transfer belt30are simultaneously transferred onto the recording material P.

The toner images on the recording material P after being subjected to the secondary transfer process are fixed by the fixing unit40, and the recording material P is passed through the inner paper-output roller44and then its conveyance direction is switched by a switching flapper73. In the case where the switching flapper73is located on a face-up output side, the recording material P is discharged in a face-up paper-output tray2by outer paper-output rollers45. On the other hand, in the case where the recording material P is located on a face-down output side, the recording material P is conveyed in the direction of reverse rollers72a,72band72cand discharged in a face-down paper-output tray3.

Incidentally, in the conveyance passage of the recording material P, a plurality of sensors for detecting passing of the recording material P are disposed. The sensors include paper-feed retry sensors64a,64b,64cand64d;a deck paper-feed sensor65; a deck drawing sensor66; a registration sensor67; an inner paper-output sensor68; a face-down paper-output sensor69; a double-side preliminary registration sensor70; a double-side paper re-feed sensor71; and the like. Further, to the paper-feed cassettes21ato21dfor accommodating the recording material P, cassette paper-presence/absence sensors63a,63b,63cand63dfor detecting the presence or absence of the recording material P are disposed. To the manual-feed tray27, a manually fed paper-presence/absence74for detecting the presence or absence of the recording material P on the manual-feed tray27is disposed. In the paper-feed deck28, a deck paper-presence/absence sensor75for detecting the presence or absence of the recording material P in the deck28is disposed.

The control means includes a control board (not shown) for controlling operations of mechanisms in the respective units and a motor drive board (not shown) or the like. The stepping motor used in this embodiment is also controlled by this control means with respect to its rotational direction (normal/reverse) and rotational angle (revolution number). The control means further includes a timer.

An operation unit704is disposed on the upper surface of the image forming apparatus main assembly1and permits selection of the paper-feed stations (paper-feed cassettes21ato21d,manual-feed tray27, and paper-feed deck28), selection of paper-output trays (face-up tray2and face-down tray3) and designation of a tab set.

Next, the operation of the image forming apparatus having the above-described structure will be explained. In the following, the case of feeding the recording material P from the paper-feed cassette21awill be described as an example.

After the lapse of a predetermined time, timed by a timer, from transmission of an image-forming-operation start signal, the recording material P is sent one by one from the paper-feed cassette21aby the pickup roller22aand then is conveyed to the registration rollers25by the BC or paper-feed rollers23athrough the drawing rollers24aand the preliminary registration rollers26. At this time, the registration rollers25are stopped and a leading end of the recording material P reaches the nip between the registration rollers25. Thereafter, the registration rollers25start rotation at a timing at the start of image formation at the image-forming station. The rotation timing is set so that the recording material P and the toner image, which has been primary-transferred onto the intermediary transfer belt30at the image-forming station, meet just at the secondary transfer nip.

On the other hand, at the image-forming station, when the image-forming start signal is sent, the toner image formed on the photosensitive drum11d,which is located most upstream in the rotational direction of the intermediary transfer belt30, is primary-transferred onto the intermediary transfer belt30at a primary transfer station by the transfer roller35dsupplied with a high voltage, through the above-mentioned process. The primary-transferred toner image is conveyed to a subsequent primary transfer station, at which image formation is performed, after the lapse of a time for conveying the toner image between first and second image-forming stations, so that a subsequent toner image is transferred and superposed on the conveyed toner image with its leading end in alignment with that of the conveyed toner image. A similar process is repeated for the remaining colors, so that four-color toner images are finally primary-transferred and superposed onto the intermediary transfer belt30.

Thereafter, when the recording material P is fed to the secondary transfer nip to contact the intermediary transfer belt30, a high voltage is applied to the secondary transfer roller36at a timing of passing of the recording material P, whereby the four-color toner images formed on the intermediary transfer belt30through the above-mentioned processes are transferred onto the recording material P at the same time. Thereafter, the recording material P is guided to a nip between the fixing roller41aand the pressure roller41bof the fixing unit40. The toner image is heated and pressed by the fixing and pressure rollers41aand41b,thus being fixed on the surface of the recording material P. The recording material P on which the toner image is fixed is then discharged in the face-up tray2or the face-down tray3, depending on the switching direction of the switching flapper73.

FIG. 6is a schematic structural view of the process cartridge (drum cartridge) to which the non-contact memory is mounted.

The drum cartridge is a unit, as a cartridge, including each of the photosensitive drums11ato11d,each of the charge rollers12ato12d,and each of the developing apparatuses14ato14d,at each of the image-forming stations.

The image forming apparatus main assembly1transmits power to the photosensitive drums11ato11dthrough driving shafts18(18ato18d) and the couplings19ato19d.The image forming apparatus main assembly1also transmits power to the charge rollers12ato12dand the developing apparatuses14ato14dthrough other driving shafts and couplings (not shown).

Further, in the respective drum cartridges, nonvolatile memory circuits15a,15b,15cand15dand antennas16a,16b,16cand16dare mounted on the same side as the couplings19a,19b,19c,and19dto which the driving force is transmitted from the driving shafts. Also on the image-forming-apparatus-main-assembly side, antennas17a,17b,17cand17dare disposed opposite to the antennas16a,16b,16cand16d,respectively. In the case where a gap between each of the antennas16ato16dand each of the antennas17ato17dis sufficiently small, when an external magnetic field is formed by the antennas17ato17don the image-forming-apparatus-main-assembly side, an induction current is generated in the antennas16ato16don the drum-cartridge side by the magnetic field. The induction current not only supplies power to the nonvolatile memory circuits15ato15d,but also adds a signal component to the magnetic field, thus permitting reading out and writing of data stored in the memories of the nonvolatile memory circuits15ato15d.

FIG. 7is a block diagram showing the general structure of the image forming apparatus main assembly1.

Referring toFIG. 7, the image forming apparatus main assembly1includes a CPU (central processing unit)701for carrying out an essential control of the image forming apparatus main assembly1. To the CPU701, an ROM (read-only memory)702in which a control program is written and an RAM (random-access memory)703functioning as working storage for permitting the performing processing are connected through an address bus and a data bus. Also to the CPU701, an operation unit704functioning as display means and key input means for the image forming apparatus main assembly1, an image forming unit705for controlling the above-mentioned various processes regarding image formation, a recording-material conveyance unit706for controlling conveyance of the recording material P onto which an image is formed, and an I/F (interface)707functioning as a communication interface between the image forming apparatus main assembly1and external units, are connected. The CPU701reads out information for processing from the ROM702on the basis of the input information from the operation unit704or the I/F707, and executes the image-forming operation on the recording material P successively.

Further, the image forming apparatus main assembly1includes, as a non-contact memory interface, a modulator708, a demodulator709, a distributor710, and antennas17a,17b,17cand17d.The non-contact memory interface has such functions that a signal modulated by the modulator708on the basis of a control signal from the CPU701is sent from the antennas17ato17dto the drum-cartridge side through the distributor710and that a signal received by the antennas17ato17dis demodulated by the demodulator709through the distributor710and is sent to the CPU701.

FIG. 8is a block diagram showing the general structure of the non-contact memory including nonvolatile memory circuits15ato15dand antennas16ato16don the drum-cartridge side.

In the non-contact memory, signals transmitted from the antennas17ato17dare received by the antennas16ato16d,respectively, and power required for actuating the nonvolatile memory circuits15ato15dis generated by a power supply803. At the same time, the signal received by a demodulator802is demodulated, and reading out and writing of data stored in a memory804are performed. Data read out from the memory804is modulated by a modulator801and is sent to the image-forming-apparatus-main-assembly side.

Features of this embodiment, i.e., processing performed at the time when reading out of data stored in the non-contact memory mounted in the drum cartridge is effected in a closed state of a cover of the image forming apparatus main assembly1will be described.

The lives of the photosensitive drums11ato11d,the charge rollers12ato12d,and the developing apparatuses14ato14dassembled in the drum cartridges are sufficiently shorter than the operation life of the image forming apparatus main assembly1, so that these members are designed to be simultaneously replaceable for each drum cartridge so as to facilitate a replacement operation of these members which have reached the ends of their lives. In such cases, it is desirable that the replacement of each of the drum cartridges can be performed at an appropriate timing by counting the number of operations for each drum cartridge so as to correctly determine the end of life of each drum cartridge and outputting a display calling the user's attention to the replacement of the drum cartridge which has reached the end of its life on the operation unit704, as a warning message of the operation life of the drum cartridge at the time when the drum cartridge has reached the end of its life.

In determining the number of operations for the respective drum cartridges to ascertain the end of life of the drum cartridge, it is possible to use the number of sheets of recording material P subjected to image formation, an energization time, a cumulative image density, and the like Such values are required to be stored even when the image forming apparatus is not energized, and in view of the possibility that a drum cartridge is used in mid-life for another image forming apparatus due to the ease of handling the drum cartridge, various information on the number of operations are stored in the non-contact memory mounted in the drum cartridge. Further, by using the non-contact memory, the problem of contact reliability of the terminals that is caused due to the repetition of mounting/demounting operations of the drum cartridge is solved.

In a state after the drum cartridges are mounted in the image forming apparatus main assembly1and the stepping motor is rotated, as described above, the drum cartridges have already been drawn by a drawing force of the driving shafts, whereby, as shown inFIG. 9, the triangular pole191aof the coupling191on the drum-cartridge side enters the triangular hole192aof the coupling192of the stepping-motor side as far as it will go. For this reason, the maximum spacing between the antennas16ato16dof the drum cartridges and the antennas17ato17dof the image forming apparatus main assembly1depends on distance the triangular pole191atravels at the time when the triangular pole191aenters the triangular hole192aas far as it will go at the couplings (191,192) and the position of the driving shaft18(18ato18d) on the stepping-motor side at the time when the spring20expands to its full length. Accordingly, the communication ability of the antennas16ato16dand17ato17dmay be designed so as to permit communication, with reliability at a minimum level, at such a distance between the antennas16ato16dand the antennas17ato17din the above-mentioned state, and thus they are not required to communicate above this level.

Incidentally, the drum cartridges are designed to be mounted by inserting them from the front side to the back side on the drawing (FIG.1). As is apparent from the perspective view of the image forming apparatus main assembly1shown inFIG. 10, it is necessary to open a front door1001of the image forming apparatus main assembly1in order that the drum cartridges are mounted in and dismounted from drum-cartridge mounting portions1002to1005.

When the front door1001is closed, an open/close detection pin1006is inserted into a hole1007for the open/close detection pin1006, and when the front door1001is opened, the open/close detection pin1006is disengaged from the hole1007. Accordingly, a sensor (not shown) is provided at a deep position of the hole1007to detect the presence or absence of the open/close detection pin1006, thus detecting the opening and closing of the front door1001. More specifically, it is possible to detect not only the opening of the front door1001by an output of the front door open/close detection sensor at any time when the drum cartridge is replaced, but also the closing of the front door1001by an output of the sensor at any time when the front door1001is closed after the replacement of the drum cartridge(s) is completed, as long as the image forming apparatus is energized.

Accordingly, when the front door1001is shifted from the open state to the closed state by reference to the output of the front door open/close detection sensor, the image forming apparatus main assembly1rotates the stepping motor in the image-forming direction and then is slightly rotated reversely in order to transmit the driving force to the drum cartridges, thus drawing therein the drum cartridges through the couplings191,192. As a result, the image forming apparatus main assembly1is placed in a state that it is capable of communicating with the non-contact memories mounted in the drum cartridges with reliability. The reason why the stepping motor is slightly rotated reversely to release the connection at the couplings191,192is because the drum cartridges can always be taken out when the front door1001is opened at the time other than image formation, even in a power-off state.

Further, this operation is always performed irrespective of the presence or absence of the drum cartridges. Thereafter, the image forming apparatus main assembly1reads out data of the memories stored in the non-contact memories by using the antennas16ato16dand17ato17dhaving the minimum communication ability as described above. If the data is correctly read out, on the basis of the data, the image forming apparatus main assembly1prepares for the image-forming operation. On the other hand, if the data is not correctly read out, on the basis of the resultant data, the image forming apparatus main assembly1performs such a treatment for the absence of the drum cartridge to be originally mounted as a result of a judgment that there is no photosensitive drum or an incorrect drum cartridge is mounted.

As described above, when the detection result of the cover (front door) required to be opened or closed for mounting the drum cartridge(s) is shifted from the open state to the closed state, the rotating shaft for transmitting the rotational driving force to the drum cartridge(s) is rotationally driven, whereby it becomes possible to immediately place the drum cartridges and the image forming apparatus main assembly1in a state that they are capable of communicating with each other with reliability by performing a minimum transmission and reception of electromagnetic waves therebetween.

An image forming apparatus of this embodiment performs the same operations as in that of Embodiment 1 except for an operation, after the image forming apparatus is turned on, which is specifically described below.

In a state that the power of the image forming apparatus is not turned on, it is impossible to judge that any specific drum cartridge is mounted in the image forming apparatus main assembly. Further, the front door open/close detection sensor is in an undetectable state, so that there is a possibility that the triangular pole and the triangular hole are appropriately engaged with each other at the (coupling) portion between the stepping motor and the photosensitive drum by performing mounting/dismounting of the drum cartridge during the power-off state.

As a result, assuming that the mounting state of the drum cartridge is unspecified at the time of turning the power on, it is possible to move an antenna for a non-contact memory mounted in the drum cartridge to a position which permits communication of the antenna with an antenna provided in the image forming apparatus main assembly when the drum cartridge is mounted by rotating the stepping motor and then slightly rotating it reversely. On the other hand, when the drum cartridge is not mounted, the stepping motor runs at idle as it is. Thereafter, the image forming apparatus reads out data by starting communication with the drum cartridge. If the data is readable, it is used for controlling the drum cartridge as it is. If the data is not readable, the operation for the absence of the appropriate drum cartridge is continued.

As described above, the rotating shaft exerting a rotational driving force on the drum cartridge is rotationally driven always when the power to the image forming apparatus is turned on, whereby it becomes possible to immediately place the drum cartridge and the image forming apparatus main assembly in a state that they are capable of communicating with each other with reliability by means of minimum levels of electromagnetic waves.

In the above-mentioned embodiment, the four-color-based full-color printer is used as the image forming apparatus of the present invention, but the present invention is also applicable to an image forming apparatus, such as a monochrome printer, a color or monochrome copying apparatus, a facsimile apparatus, or the like. The present invention is further applicable, in addition to the image forming apparatus, to an ordinary apparatus which transmits a rotational driving force to a load apparatus (unit) detachably mountable to an apparatus main assembly and provided with a non-contact memory.

INDUSTRIAL APPLICABILITY

As described hereinabove, according to the present invention, there is provided an image forming apparatus including a process cartridge which is detachably mountable to an apparatus main assembly and includes a non-contact memory, antennas for performing communication of data stored in the non-contact memory with the apparatus main assembly, and a rotating shaft (axis) for receiving a rotational driving force from the apparatus main assembly which includes antennas for performing communication of data stored in the non-contact memory with the antennas of the process cartridge and a connection (coupling) portion for exerting the rotational driving force on the process cartridge. In the image forming apparatus, the apparatus main assembly rotationally drives the connection portion before reading out of the data stored in the non-contact memory, which is mounted in the process cartridge, so that it becomes possible to effectively read out the data immediately and with reliability without outputting more electromagnetic waves than necessary, to the non-contact memory mounted in the process cartridge, which is detachably mountable to the apparatus main assembly.

While the invention has been described with reference to the embodiments and structures disclosed herein, it is not confined to the details set forth and this application is intended to cover such modifications or changes as may come within the purpose of the improvements or the scope of the following claims.