Abstract:
The low-cost, space-saving process cartridge identification mechanism identifies many types of process cartridge without requiring a new electrical logic circuit. Even if a pressing piece goes into a detection portion, switches are not turned on and hence a mounted process cartridge is not detected as long as the pressing piece does not push down a manipulation lever. Identification pieces are provided in an identification unit separately from the pressing piece. In this manner, a mechanism for mechanically identifying a process cartridge based on whether the identification pieces are interfered with by the interference pieces irrespective of turning-on/off of the switches. As a result, by combining combinations of the pressing piece and the manipulation lever and combinations of the identification piece and the interference piece, many combinations of an image forming apparatus and a process cartridge can be obtained at a low cost with space saving without requiring a new electrical logic circuit.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a process cartridge and a process cartridge identification mechanism for image formation that is mounted in image forming apparatuses such as a laser printer, a facsimile machine, and a copier, as well as to an identification mechanism for such a process cartridge. 
     2. Description of the Related Art 
     Among image forming apparatuses are ones in which a process cartridge unit formed by accommodating a photoreceptor drum, a developer, etc. in a housing is provided in a detachable manner to improve the ease of maintenance and provide better service. 
     The specifications of internal functional components and a toner may vary among process cartridges due to various differences in the specifications of apparatus main bodies where the process cartridges are used, whereas external components such as a housing are common to the process cartridges. In this case, if a process cartridge is not compatible with an apparatus main body, a failure in image quality or malfunctioning of the apparatus may occur. To prevent such an event, it is necessary to employ a mechanism for prohibiting the use of such a process cartridge. 
     However, a conventional identification mechanism as disclosed in Japanese Unexamined Patent Publication No. Hei. 7-152307, for example, which electrically detects a process cartridge type, is not so configured as to identify many process cartridge types. 
     Japanese Unexamined Patent Publication No. Hei. 9-185311 discloses an identification mechanism in which the logo mark of a process cartridge is recognized by means of a switch. However, this identification mechanism has a problem that a process cartridge cannot be identified unless it is mounted correctly because the structure of the mechanism does not allow a large projection/recess amount of a logo mark nor a long stroke of the switch. 
     Further, it is necessary to provide, in addition to such an identification mechanism, the following components in the mounting section. That is, as shown in FIG. 15, it is necessary to provide not only a detection switch  88  for detecting whether a process cartridge is mounted and an interlock switch for turning off the apparatus when a process cartridge is removed or a main body cover is opened, but also a power switch  90  for turning off the power of a laser diode to secure the safety. 
     In view of the above, for example, a configuration is possible in which seven projection plates  92  are provided on the process cartridge  10  side and eight engagement portions  96  are provided at such positions as to be able to engage the projection plates  92  by elongating an actuator portion  94  on the mounting section side in the horizontal direction. A manipulation lever  98  for manipulating the detection switch  88  and the power switch  90  is selectively provided in the engagement portions  96  and is pushed down by the corresponding one of the projection plates  92 . This configuration enables seven combinations of an image forming apparatus and a process cartridge. However, since the actuator portion  94  occupies a large space in the horizontal direction, this configuration is not efficient in terms of space utilization. 
     It is also possible to provide a maximum of  16  combinations by using an electrical logic circuit having 4-bit switches. However, a large-size assembly is needed to incorporate, to secure the safety, switches having a capacity large enough to turn off the power of a laser diode. It is noted that it is possible to replace the power switch  90  for turning off the power of the laser diode with another means. 
     SUMMARY OF THE INVENTION 
     The present invention has been made in view of the above circumstances and provides a low-cost, space-saving process cartridge and a process cartridge identification mechanism which can identify many process cartridge types and has a process cartridge detection function without requiring a new electrical logic circuit, as well as to a process cartridge to be identified by such an identification mechanism. 
     According to a first aspect of the invention, a process cartridge is mounted in a mounting section of an image forming apparatus. The process cartridge is provided with a pressing member. When the process cartridge is mounted in the mounting section, the pressing member operates an operating member provided in the image forming apparatus if the pressing member corresponds to the operating member and thereby causes a detection device to detect that the process cartridge is mounted regularly. In other words, if the pressing member does not correspond to the operating member, the operating member is not operated and the detecting device does not detect the process cartridge even when the process cartridge is mounted. 
     Further, a projection/recess member is provided in the mounting section separately from the operating member, and an identification member is provided in the process cartridge separately from the pressing member. In this manner, a mechanism for mechanically identifying a process cartridge irrespective of the detection device based on whether the identification member is interfered with by a projection portion of the projection/recess member is provided. 
     With the above configuration, by combining combinations of the pressing member and the operating member and combinations of the identification member and the projection/recess member, many combinations of an image forming apparatus and a process cartridge can be obtained at a low cost with space saving without requiring a new electrical logic circuit. 
     Accordion to the second aspect of the invention, the projection/recess member may be a stopper member that has different projection/recess forms and can be attached to and removed from the mounting section. 
     According to the third aspect of the invention, the identification member may be an identification unit having a claw piece that is fixed to the process cartridge by one-touch action. 
     According to the fourth aspect of the invention, a cover that opens and closes the mounting section may be closable even when the identification member is interfered with by the projection portion of the projection/recess member. 
     According to the fifth aspect of the invention, the projection/recess member may have a projection/recess form that is a projection approximately parallel with a mounting direction of the process cartridge. 
     The identification member may be provided at an end portion of the process cartridge. 
     According to the 7-9 aspects of the invention, an identification unit is fixed to a surface of a process cartridge. The identification unit is provided with a pressing member and an identification member. As in the case of the first aspect, many combinations of an image forming apparatus and a process cartridge can be obtained at a low cost with space saving without requiring a new electrical logic circuit. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a process cartridge identification mechanism according to an embodiment of the present invention; 
     FIG. 2 is a perspective view showing a positional relationship between a stopper member and an identification unit according to the embodiment; 
     FIG. 3 is a partially cutaway perspective view showing a positional relationship between the stopper member and the identification unit according to the embodiment; 
     FIG. 4 is a side sectional view showing the attachment structure of the identification unit according to the embodiment; 
     FIGS. 5-7 are side sectional views showing movement of a manipulation plate in the embodiment; 
     FIGS. 8 and 9 are a perspective view and a front view, respectively, showing a corresponding relationship between the stopper member and the identification unit in the embodiment; 
     FIG. 10 is a front view showing a state that the stopper member and the identification unit are engaged with each other in the embodiment; 
     FIGS. 11 and 12 are a perspective view and a front view, respectively, showing a state that the stopper member and the identification unit do not conform to each other in the embodiment; 
     FIG. 13 schematically shows a specific combination of the identification unit side and the detection device side; 
     FIG. 14 is a table showing combinations of the identification unit side and the detection device side; and 
     FIG. 15 is a perspective view showing a conventional process cartridge identification mechanism. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     A process cartridge identification mechanism according to an embodiment of the present invention will be hereinafter described with reference to the accompanying drawings. 
     As shown in FIGS. 1-4, a process cartridge  10  has a housing  12  that accommodates a photoreceptor drum, a development roller, and a developer. An identification unit  20  in which a pressing piece  16  and identification pieces  18  project forward from a base plate  14  is attached to the front end portion of the housing  12 . The top portions of the pressing piece  16  and the identification pieces  18  are connected to each other by a reinforcement plate  22 . 
     The bottom portion of the base plate  14  is formed with hook claws  99 . The hook claws  99  are inserted and set in an opening  21  of the housing  12 , and then the identification unit  20  is turned toward the housing  12 . Two claw pieces  24  project from the back surface of the base plate  14 . The tip portion of each claw piece  24  is formed with a claw portion  24 A whose thickness decreases toward the tip. When the identification unit  20  is turned, the claw portions  24 A are fixed to engagement holes  26  of the housing  12  by one-touch action, whereby the identification unit  20  is attached to the housing  12 . In this manner, the identification unit  20  is configured so as not to be removed from the outside once attached to the housing  12  unless it is broken. Since the identification unit  20  is disposed at an end portion of the housing  12 , the end portion that tends to be a dead space can be utilized effectively. 
     On the other hand, as shown in FIGS. 2 and 3, a detecting device  30  is provided on the mounting section  28  side. A detection switch  36  that is on/off-manipulated by a switch knob  34  and detects presence of the process cartridge  10  and a power switch  40  that is manipulated by a switch knob  38  and turns on/off a laser light source of an optical scanning device are provided in a housing  32  of the detection device  30 . 
     As shown in FIGS. 5 and 6, the switch knobs  34  and  38  are turned on or off at the same time being pushed by a leaf spring  42 . The leaf spring  42  is bent so as to assume a J-shape and one end of the leaf spring  42 , that is, the end of its straight portion, is engaged with a presser portion  46  of a manipulation plate  44 . 
     A pin  48  extending from a central portion of the manipulation plate  44  is supported by a side plate  31  of the housing  32  in such a manner that the manipulation plate  44  is swingable. A presser plate  50  located at a central portion of the manipulation plate  44  presses the other end of the leaf spring  42 , that is, the end of its curved portion. 
     With the above structure, when the manipulation plate  44  is free, the urging force of the leaf spring  42 , the returning forces of the switch knobs  34  and  38 , and the angular moment that occurs because the centers of gravity of the manipulation plate  44  and the leaf spring  42  are located on the left of the pin  48  cause the manipulation plate  44  to incline in such a direction that the presser portion  46  goes down. Therefore, the switch knobs  34  and  38  are not pushed up by the leaf spring  42 . 
     A manipulation lever  52  is attached to the tip portion of the manipulation plate  44 . The tip portion of the manipulation lever  52  is formed, at the top, with a recessed engagement portion  54 . When the manipulation plate  44  is inclined in such a direction that the presser portion  46  goes down, the engagement portion  54  engages a projection portion  58  that is provided at the end of a top cover  56 . 
     As shown in FIGS. 2 and 3, three partition plates  60  are provided between the side plates  31 , whereby four gaps (detection portions  62 ) where the manipulation lever  52  can move vertically are formed. The pressing piece  16  goes into the corresponding one of the detection portions  62  and pushes down the manipulation lever  52 , whereby the manipulation plate  44  is swung and the leaf spring  42  turns on the detection switch  36  and the power switch  40 . 
     A receiving stage  64  is formed, as part of the walls, outside one of the side plates  31 . The receiving stage  64  is formed with positioning pins  66  and a screw hole  68 . A stopper member  76  having a substrate  74  that is formed with engagement holes  70  to engage the positioning pins  66  and a through-hole  72  into which a screw to be screwed to the screw hole  68  is to be inserted is set on the receiving stage  64 . 
     The stopper member  76  has a vertical wall  78  that erects from the substrate  74  and two interference pieces  80  that project horizontally from the vertical wall  78 . If at least one of the interference pieces  80  butts against the identification pieces  18 , it means that the process cartridge  10  is not compatible with the image forming apparatus. However, even in such a case, a main body cover (not shown) of the image forming apparatus can be closed. 
     That is, the height relationship among the manipulation lever  52 , the interference pieces  80 , and the identification pieces  18  is set in such a manner that even if the pressing piece  16  corresponds to the manipulation lever  52  that is located in one of the detection portions  62 , the pressing piece  16  cannot push down the manipulation lever  52  completely as long as the identification pieces  18  butt against at least one of the interference pieces  80 . By making the main body cover (not shown) closable even in a state that the manipulation lever  52  cannot be pushed down completely, an event can be prevented that a user who does not recognize incompatibility between the process cartridge  10  and the image forming apparatus tries to forcibly push the process cartridge  10  in place. Therefore, the apparatus main body can be prevented from being damaged. A message to the effect that the process cartridge  10  is not correct is displayed if the switches  36  and  40  are not turned on. 
     Since the interference pieces  80  and the vertical wall  78  extend in the direction that is approximately parallel with the mounting direction of the process cartridge  10 , the process cartridge  10  can be mounted and identified reliably even if there is some play due to an error in manufacture, for example. 
     Next, the process cartridge identification mechanism according to the embodiment will be described by using a specific example. 
     If the process cartridge  10  is compatible with the image forming apparatus, the pressing piece  16  of the identification unit  20  goes into the corresponding detection portion  62  and pushes down the manipulation lever  52  of the detection device  30  as shown in FIGS. 8-10. As shown in FIG. 10, since the interference pieces  80  do not interfere with the identification pieces  18 , the process cartridge  10  can be mounted in the mounting section without any problem. 
     Since the pressing piece  16  pushes down the manipulation lever  52 , the manipulation lever  44  is swung clockwise and the leaf spring  42  pushes up the switch knobs  34  and  38  as shown in FIG. 6, whereby the detection switch  36  and the power switch  40  are turned on. Mounting of the process cartridge  10  is confirmed in this manner to establish a state the laser light source can be turned on. 
     The function of the leaf spring  42  will now be described. 
     When the inserted process cartridge  10  comes to a position immediately before the mounting position, the switches  36  and  40  are turned on by the leaf spring  42  as shown in FIG.  6 . When the process cartridge  10  is set at the mounting position, the leaf spring  42  keeps the switches  36  and  40  in the on-states while being stopped and bent by the lower end of the substrate  98  of the switches  36  and  40  (the end of the leaf spring  42  is separated from the presser portion  46 ) as shown in FIG.  7 . 
     The leaf spring  42  increases the reliability because it can push up the switches  36  and  40  even if the mounting position (in the vertical direction) of the process cartridge  10  varies in a wide range. Even if the process cartridge  10  goes down from the position of FIG. 7, the leaf spring  42  is further bent and the on-states are continued without destroying the switches  36  and  40 . 
     Assume a case that a stopper member  84  of another product type is attached to the receiving stage  64  without switching the identification unit  20  as shown in FIG.  11  and FIG.  12 . In this case, although the central identification piece  18  receives no interference, the left-hand identification piece  18  butts against one of the interference pieces  86 . 
     Even if the left-hand identification piece  18  butts against the one interference piece  86 , the process cartridge  10  can be moved to such a position that the main body cover can be closed and hence no unduly strong force is applied to the apparatus main body. In this state, although the pressing piece  16  is in the corresponding detection portion  62 , it does not push down the manipulation lever  52  completely. Therefore, the detection switch  36  and the power switch  40  are not turned on and a message to the effect that the process cartridge  10  is not compatible is displayed. This allows a user to recognize the use of an erroneous process cartridge  10 . 
     The identification mechanism of this embodiment can accommodate many product types by switching the combination of the arrangement of identification unit the manipulation lever  52  and the stopper member. Therefore, during manufacture, management may be made on a stopper member/identification unit basis rather than a process cartridge housing basis. This saves the storage space and makes it easier to change the metal mold. 
     Finally, what number of combinations are possible will be described with reference to a schematic diagram of FIG. 13 and a table of FIG.  14 . The invention is not limited to the following combinations but intended to reduce the cost and the necessary space by enabling many combinations by providing an electrical detection part and a mechanical identification part. 
     In FIG. 14, the positions of the pressing piece of the identification unit  20  and the positions of the manipulation lever on the detection device  30  side are represented by numerals  1 ,  2 ,  3 , and  4 . The positions of the identification piece of the identification unit  20  and the positions of the interference piece of the stopper member on the detection device  30  side are represented by characters A, B, D, and M. 
     As shown in FIG. 13, the table of FIG. 14 should be seen in such a manner that when the identification unit  20  side is in the No.  1  state (“MA 1 ”), only the combination “DB 1 ” is allowed on the detection device  30  side. For example, if the detection device  30  side in the “DB 2 ” state, the process cartridge  10  can a be mounted without receiving any interference because the pressing piece goes into the corresponding detection portion and the interference pieces do not interfere with the identification pieces. However, since the pressing piece located at position “ 1 ”, does not correspond to the manipulation lever located at position “ 2 ,” neither the detection switch  36  nor the power switch  40  is turned on. 
     That is, FIG. 14 shows that a relationship (maximum number of combinations)=(number of kinds of pressing piece (number of kinds of manipulation lever))×(number of kinds of identification piece (number of kinds of interference piece)) holds and 16 combinations are possible. Although two identification pieces and two interference pieces are provided in the embodiment, eight combinations are still possible if one identification piece and one interference piece are provided. 
     Having the above configuration, the invention makes it possible to maintain a process cartridge detection function by using a conventional detection device without the need for providing a new logic circuit, as well as to identify process cartridge types at a low cost with space saving.