JP2005215104A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To automatically push out a process unit from an equipment body, when a developer is replaced. <P>SOLUTION: The image forming apparatus, having an opening/closing door which is opened and closed when the replaceable image forming process unit is replaced, is equipped with a detecting means 20 of detecting, when the image forming process unit 6 needs to be replaced; a push-out means 21 of pushing the image forming process unit in a loaded state out of the equipment body; and a control part 40 which makes the push-out means 21 perform the push-out operation, based on the detection result of the detecting means 20. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus having a replaceable image forming process unit such as a laser printer.

  2. Description of the Related Art Conventionally, in an image forming apparatus such as a laser printer, at least two of a photosensitive drum, a charger, a developing roller, a cleaning roller, a toner box, and a toner supply roller are provided in a casing in order to facilitate handling during maintenance. The cartridge is housed in a cartridge, and the cartridge is detachable from the apparatus main body.

  In such an image forming apparatus, when the remaining amount of toner is detected by the detection unit and becomes equal to or less than a predetermined amount, a cartridge replacement display is performed on the display panel. According to the display, the operator opens the open / close door, inserts his / her hand into the apparatus main body, grasps the cartridge gripping part, and removes it from the apparatus main body. Then, the cartridge after toner replenishment or a new cartridge is exchanged by the operator pushing the opening / closing door again into a predetermined mounting position.

  In order to eliminate the troublesomeness of the operator's replacement as much as possible, as shown in Patent Document 1, when the operator opens the open / close door in accordance with the display on the display panel, a plurality of gear combinations linked to the door are combined. A mechanism has been proposed in which the mounting base on which the cartridge is mounted is moved by the mechanism and moved to the door side, and the cartridge is moved to the outside of the apparatus main body, so that replacement is facilitated. .

Further, in Patent Document 2, as in Patent Document 1, when the operator opens the door in accordance with the display on the display panel, hooks formed at the base end of the door are protruded from both ends of the cartridge. There has also been proposed a cartridge which is easily exchanged by engaging the pin and moving the cartridge to the outside of the apparatus main body.
Japanese Patent Laid-Open No. 2000-75763 Japanese Patent No. 3304180

  However, in each of the above prior arts, the opening / closing door of the device main body remains closed, and it is not known until the cartridge replacement display on the display panel is seen. Therefore, it is said that the operator only needs to replace the device when using the device. There was inconvenience. In addition, when the operator is a beginner or unfamiliar, the opening / closing operation for replacement is often not immediately known, and it may take time for the replacement.

  The present invention has been made to solve the above-described conventional problems, and an image forming apparatus in which a process unit is automatically pushed out of the apparatus body when the image forming process unit needs to be replaced. The purpose is to provide.

  In order to achieve the above object, the invention described in claim 1 is directed to an image forming apparatus having a replaceable image forming process unit and an opening / closing door that opens and closes for replacement of the image forming process unit. Detection means for detecting the replacement time of the unit, extrusion means for opening the opening / closing door to push the image forming process unit from the mounted state to the outside of the apparatus main body, and extrusion of the extrusion means based on the detection result of the detection means And a control unit for performing the operation.

  Thus, the extrusion control of the extrusion means is performed based on the detection result of the detection means for detecting the replacement time of the process unit, and the image forming process unit is automatically outside the apparatus main body when the replacement time of the process unit is reached. Extruded.

  According to a second aspect of the present invention, a registration roller, a transfer unit that transfers an image onto a sheet on the downstream side of the registration roller, a paper discharge roller that discharges the sheet onto which the image has been transferred, and a replaceable image In an image forming apparatus having a forming process unit and an opening / closing door that opens and closes when the image forming process unit is replaced, a detection unit that detects a replacement time of the image forming process unit, and a supply that detects the presence or absence of paper in the registration roller A paper presence / absence detecting means; a paper passage detecting means for detecting passage of the rear end of the paper in the paper discharge roller; and an extruding means for opening the open / close door to push the image forming process unit out of a mounted state. And a control unit for performing the pushing-out operation of the pushing-out means based on the detection results of the detecting means.

  Thus, the push-out control of the push-out means is performed based on the detection results of the detection means for detecting the replacement time, the paper feed presence / absence detection means and the paper passage detection means, and the replacement time of the image forming process unit is reached. The process unit is automatically pushed out of the main body.

  According to a third aspect of the present invention, in the second aspect of the present invention, the detection means for detecting the replacement time is a residual for detecting the remaining amount of the developer in the developer storage portion of the image forming process unit. It is quantity detection means. Thereby, the replacement time can be reliably detected.

  According to a fourth aspect of the present invention, in the invention of the third aspect, the remaining amount detecting means detects that the remaining amount of the developer in the developer containing portion has decreased to a predetermined amount, and When the paper presence / absence detecting means detects that no paper is present in the registration roller, and the paper passage detecting means detects that the paper trailing edge has passed in the paper discharge roller, The extrusion means is made to perform an extrusion operation.

  As a result, when the remaining amount of the developer in the developer storage section becomes a predetermined amount or less, the image forming process unit is automatically pushed out of the apparatus body in synchronization with the unfeeding state and the sheet passing state. The

  According to a fifth aspect of the present invention, in the invention according to any one of the first to fourth aspects, the door is provided between the opening / closing door and the device main body, and maintains the closed state of the opening / closing door. And a pushing mechanism for releasing the holding by the holding mechanism by engaging with a part of the image forming process unit pushed out of the apparatus main body from the mounted state. Features.

  As a result, the image forming process unit is automatically released from the holding door and pushed out of the device main body.

  According to a sixth aspect of the present invention, in the invention according to any one of the first to fifth aspects, the push-out means abuts on the image forming process unit so that the pushing force is directly applied to the image forming process unit. It is characterized by acting.

  Thus, the image forming process unit is automatically pushed out of the apparatus main body by the pushing means directly contacting the image forming process unit.

  According to a seventh aspect of the invention, in the invention according to any one of the first to sixth aspects, the image forming process unit is mounted on a mounting table that is movable from a mounted state to a position outside the apparatus body. The pushing force of the pushing means is applied to the image forming process unit or the mounting table.

  Thereby, the image forming process unit mounted on the mounting table is automatically pushed out of the apparatus main body.

  According to an eighth aspect of the present invention, in the invention according to any one of the first to seventh aspects, the pushing means generates an urging force that acts on the image forming process unit or the mounting table. A biasing means and a holding means for holding the image forming process unit or the mounting table in a predetermined position, and the biasing means is released when the holding means releases the holding in the predetermined position by an extrusion command of the control unit. The means is characterized in that the image forming process unit or the mounting table is pushed out by an urging force.

  Thus, the push-out means reliably pushes the image forming process unit out of the apparatus main body automatically with a simple configuration including the biasing means and the holding means.

  The invention according to claim 9 is the invention according to claim 8, wherein the biasing means includes a bottomed cylindrical body having an opening at one end and fixed to the apparatus body, and the bottomed cylindrical body. A piston member that is inserted and has one end protruding from the opening, and the piston member that is disposed between the other end of the piston member and the bottom of the bottomed cylindrical body faces the image forming process unit. The projecting end of the piston member is engaged and held at a predetermined position by the holding means, and the piston member is attached when the engagement is released by an extrusion command of the control unit. A force is applied to the image forming process unit or the mounting table.

  Thus, the urging means has a simple configuration in which the piston member is urged by the spring member, and reliably pushes the image forming process unit out of the apparatus main body.

  According to a tenth aspect of the present invention, in the invention according to the ninth aspect, the holding means is formed from a solenoid mounted on the apparatus main body, and a movable shaft of the solenoid is formed at the protruding end of the piston member. Engage with the stopper to hold the piston member at a predetermined position, operate the movable shaft of the solenoid in response to an extrusion command from the control unit to release the engagement with the stopper and release the biasing force of the piston member Is operated on the image forming process unit or the mounting table.

  As a result, the piston member is held by a simple holding means called a solenoid, so that the configuration becomes simple and the image forming process unit is automatically pushed out of the apparatus main body.

  According to an eleventh aspect of the present invention, in the invention according to the eighth aspect, the holding means is engaged with a mounting table on which the image forming process unit is mounted, and the urging means is always the image forming process unit. Alternatively, when the pressing force is applied to the mounting table and the holding unit is disengaged from the mounting table by the pressing command from the control unit, the biasing unit pushes the image forming process unit by the biasing force. It is characterized by that.

  Thereby, the image forming process unit mounted on the mounting table is automatically pushed out of the apparatus main body.

  According to a twelfth aspect of the present invention, there is provided an image forming apparatus comprising: a plurality of replaceable image forming process units provided for each color; and an opening / closing door that opens and closes for replacement of the image forming process units. Detecting means for detecting the replacement time of each image forming process unit and provided corresponding to each image forming process unit to open the door and push the image forming process unit out of the main body from the mounted state. A plurality of pushing means, and a control unit for performing the pushing operation of each pushing means based on the detection result of the detecting means.

  As a result, the extrusion control of each extrusion means is performed based on the detection result of the detection means for detecting the replacement timing of the image forming process unit provided for each color, and image formation is performed when the replacement timing of the process unit is reached. The process unit is automatically pushed out of the equipment body. As a result, the user can easily know which color image forming process unit is to be replaced.

According to the first to twelfth aspects, the convenience of the operator is improved in the following points.
(1) When the image forming process unit needs to be replaced, the process unit is automatically pushed out from the mounted state to the outside of the apparatus main body. Therefore, it is easy to confirm visually, and since it is not known until the display of replacement of the display panel is seen as in the past, the inconvenience that the operator notices that the replacement is necessary only when the device is used is eliminated.
(2) Even when the operator is a beginner or unfamiliar, the process unit is automatically pushed out of the main body of the apparatus, so that the replacement operation can be performed easily and reliably.

  In an image forming apparatus having a replaceable image forming process unit and an opening / closing door that opens and closes for replacement of the image forming process unit, a detecting means for detecting the replacement timing of the image forming process unit, and the opening / closing door are opened. And an extruding unit that extrudes the image forming process unit from the mounted state to the outside of the apparatus main body, and a control unit that performs an extruding operation of the extruding unit based on the detection result of the detecting unit.

  Hereinafter, an image forming apparatus according to the present invention will be described using a laser printer as an example.

  FIG. 1 is a side sectional view of the laser printer 1. The laser printer 1 includes a main body 2, an opening / closing door 3 provided on a front panel 2 a of the main body 2, a paper transport mechanism 4 provided in the main body 2, a scanner unit 5, a process unit 6, a fixing unit 7 and the like. The rear upper surface 2b of the main body 2 functions as a tray that receives printed sheets.

  Here, the scanner unit 5, the process unit 6, the fixing unit 7, and the like correspond to the print mechanism unit. A process unit 6 as an image forming process unit houses a photosensitive drum 8, a scorotron charger 9, a developing roller 10, a developer supply roller 13, a developer box 11 as a developer storage unit, and the like in a casing. The cartridge structure is detachable from a predetermined part in the body. As a result, the process unit 6 is removed from the main body 2 and easily replaced with a new process unit 6. The transfer roller 12 is disposed in contact with the photosensitive drum 8, and a predetermined transfer bias voltage is applied to the transfer roller.

  The open / close door 3 has a lower end supported by a support shaft 15 so as to be pivotable to the front panel 2a, and an upper end opened at a predetermined interval. The process unit 6 is replaced using the opening / closing of the opening / closing door 3. When the opening / closing door 3 is closed, the opening / closing door 3 and the main body 2 are held in a closed state by concave-convex engagement as will be described later.

  A cassette 16 for automatic paper feeding is mounted at the bottom of the main body 2, and the paper P in the cassette 16 is separated by a pickup roller 17 and conveyed toward a pair of registration rollers 18 and 19. After the leading ends of the sheets P are aligned by the registration rollers 18 and 19, they are conveyed to the process unit 6. Of the pair of registration rollers 18, 19, one registration roller 18 is a driving roller, and the other registration roller 19 is a driven roller.

  The scanner unit 5 is disposed on the upper side of the process unit 6 and includes a laser light emitting unit (not shown), a polygon mirror 5a, lenses 5b and 5c, a reflecting mirror 5d, and the like. The laser beam from the scanner unit 5 irradiates and exposes the outer periphery of the rotating photosensitive drum 8 charged by the charger 9 by high-speed scanning, as indicated by the solid arrow. As a result, an electrostatic latent image is formed on the surface of the photosensitive drum 8.

  The process unit has a combination structure of a photosensitive unit that stores a photosensitive drum and a charger and a developer storage unit that stores a developing roller, a developer supply roller, a developer box, and the like. The developer storage unit may be configured to be detachable. Alternatively, a photosensitive drum may be fixedly disposed inside the apparatus main body, and only the developer storage unit may be detachably attached to the photosensitive drum as an image forming process unit. As described above, when the process unit is composed of a combination of the photosensitive unit and the developer storage unit, the developer storage unit is removed from the photosensitive unit and replaced with a new developer storage unit. It will be.

  The developer in the developer box 11 is supplied to the developing roller 10 via the developer supplying roller 13, is regulated by the developer layer having a constant thickness by the blade 10 a and is carried on the developing roller 10, and is held on the photosensitive drum 8. Supplied.

  Further, the electrostatic latent image formed on the surface of the photosensitive drum 8 is visualized by the developer from the developing roller 10, and the sheet P passes while the sheet P passes between the photosensitive drum 8 and the transfer roller 12. Is transcribed. The transferred paper P is sent into the fixing unit 7 and fixed. The developer remaining on the surface of the photosensitive drum 8 is collected by the developing roller 10. The fixing unit 7 heat-fixes the developer on the paper, and includes a heating roller 7a and a pressing roller 7b pressed against the heating roller 7a. Conveying rollers 22a and 23a are provided on the downstream side of both rollers 7a and 7b, and discharging rollers 22 and 23 are provided for discharging the paper P conveyed by these conveying rollers to the outside of the main body 2. .

  Next, replacement of the process unit 6 will be described. When the remaining amount of the developer in the developer box 11 becomes equal to or less than the predetermined amount, the process unit 6 automatically opens the open / close door 3 from the mounted state by the pushing means 21 to the outside of the apparatus main body 2. Extruded. In this case, with the open / close door 3 opened, the process unit 6 is pushed out to a specific position where it can be easily taken out and held at the specific position. As a result, the process unit 6 can be easily replaced.

  Further, the process unit 6 is provided with an initial mounting sensor 33 constituted by a fuse. When an unused process unit 6 is first attached to the main body 2, the fuse is energized in contact with a contact (not shown) on the main body 2 side, and blown by the energization. The control unit 40 described later detects whether or not the process unit 6 has been used by detecting the presence or absence of an energization current to the fuse.

  Further, an optical sensor 20 is provided as a developer remaining amount detecting means for detecting the remaining amount of developer in the developer box 11. The optical sensor 20 is composed of a transmissive sensor composed of a light emitting part and a light receiving part. That is, the light passage windows are provided so as to face the appropriate positions on the both side walls of the developer box 11, and the light emitting portion and the light receiving portion are attached to the main body frame respectively facing the light passage windows. Yes. This configuration is well known, for example, in Japanese Patent Laid-Open No. 2001-350339.

  When the developer remains sufficiently in the developer box 11, the light between the light emitting portion and the light receiving portion of the optical sensor 20 is blocked by the developer, so that there is sufficient developer. Is detected. Further, when the developer does not remain in the developer box 11 or only a little remains, the light from the light emitting portion is received by the light receiving portion without being blocked by the developer. Thereby, it is detected that the remaining amount of the developer is small.

  As a detecting means for detecting the replacement time of the process unit 6, an optical sensor 20 for detecting the remaining amount of the developer is used. A counting means for counting the number of rotations of the developing roller 10 together with the optical sensor 20 is provided. This is provided as a control function of the control unit 40 described later. The counting means cumulatively counts the number of rotations of the developing roller 10 based on the number of rotations of the driving motor that drives the photosensitive drum 8 and the developing roller 10 and the driving time. When the cumulative count value reaches a predetermined number of rotations, a determination signal is generated indicating that the process unit 6 has reached the replacement time. The predetermined number of rotations is determined based on the lifetime of a known seal member that is always in contact with the developing roller 10 in order to prevent the developer from leaking from the developing roller 10. Therefore, if the predetermined number of rotations of the developing roller 10 is set in advance based on the life of the seal member, it is possible to detect the deterioration of the seal member of the developing roller 10 when the predetermined number of rotations is reached. . Accordingly, the detecting means for detecting the replacement timing of the image forming process unit may be a means for detecting or determining not only the remaining amount of the developer but also the lifetime of the components of the process unit.

  In addition to the optical sensor 20, a paper feed sensor 34 as a paper feed presence / absence detection means and a paper discharge sensor 35 as a paper passage detection means are provided. The paper feed sensor 34 detects the paper conveyance status of the registration rollers 18 and 19, that is, whether or not the leading edge of the paper P has reached the vicinity of the upstream side of the registration rollers 18 and 19. Is arranged. The paper discharge sensor 35 detects whether or not the trailing edge of the paper P has passed at the position where the paper discharge rollers 22 and 23 are disposed, and is disposed upstream of the paper discharge rollers 22 and 23. Similarly to the optical sensor 20, the paper feed sensor 34 and the paper discharge sensor 35 have a configuration including a light emitting unit and a light receiving unit. The conveyance state of is detected.

  In order to extrude the process unit 6 from the mounted state to the outside of the apparatus main body 2, an extruding mechanism 21 as an extruding means is disposed on the apparatus inside side from a predetermined mounting position of the process unit 6. The extrusion mechanism 21 is configured to operate according to an extrusion command from the control unit 40 described later. As shown in FIG. 3, the pushing mechanism 21 has a biasing device 24 as a biasing unit that generates a biasing force for pushing the process unit 6, and the biasing force from the biasing device 24 acts on the process unit 6. And a solenoid 30 as a holding means for preventing this.

  That is, as shown in FIG. 3, the biasing device 24 includes a bottomed cylindrical body 26, a piston member 27, and a spring member 28. The bottomed cylindrical body 26 has an opening 25 at one end and is fixed to the device main body 2. The opening 25 opens toward the mounting position side of the process unit 6. The piston member 27 is inserted into the bottomed cylindrical body 26, and one end portion 27 a thereof protrudes from the opening 25. The spring member 28 is disposed between the other end portion 27 b of the piston member 27 and the bottom portion 26 a of the bottomed cylindrical body 26, and biases the piston member 27 toward the mounting position side of the process unit 6. A stopper portion 29 is formed on the protruding end portion 27 a of the piston member 27.

  A solenoid 30 as a holding means is arranged in the apparatus main body 2 and is composed of a movable shaft 31 that moves by receiving an electromagnetic action, and a spring member 32 that urges the movable shaft 31 in a direction that always projects. Yes. The movable shaft 31 of the solenoid 30 is provided to engage with the stopper portion 29 of the piston member 27 at the protruding position. When the solenoid 30 is excited by an extrusion command from the control unit 33 described later, the movable shaft 31 is moved from the protruding position to the retracted position against the biasing force of the spring member 32, and the engagement with the stopper unit 29 is released. Is done. Thereby, the projecting end portion 27 a of the piston member 27 directly presses the process unit 6 by the biasing force of the spring member 28, and the process unit 6 is pushed out of the main body 2.

  The urging device 24 includes the bottomed cylindrical body 26, the spring member 28, and the piston member 27. However, the spring member 28 may be another elastic member, and the urging device 24 itself It is optional to use other configurations, for example, a unit that electromagnetically generates a biasing force. Further, although the solenoid 30 is used as the holding means, the configuration of other means is optional.

  Further, as shown in FIG. 4, an edge 3 a that extends horizontally toward the inside of the main body is formed at the upper end of the open / close door 3. A recess 2c is formed at an upper portion of the device main body 2 where the open / close door 3 is closed, and an edge 3a of the open / close door 3 is formed with a protrusion 3c that engages with the recess 2c. The projection 3c is elastically deformed and engaged with the recess 2c, whereby the open / close door 3 is held in a closed state with respect to the main body 2. The protrusion 3 c and the recess 2 c constitute a holding mechanism that holds the open / close door 3 in a closed state. A protrusion 3b is formed on the front end side of the edge 3a with respect to the protrusion 3c of the open / close door 3. The protruding portion 3 b extends to a position where it can be slightly engaged with the upper front portion of the process unit 6. The protruding portion 3b acts to release the engagement holding state between the protrusion 3c and the recessed portion 2c, and constitutes a releasing member as a part of the pushing mechanism 21.

  Further, the engagement amount between the protrusion 3b of the door 3 and the upper front portion of the process unit 6 is set to be equal to or larger than the engagement amount between the protrusion 3c of the door 3 and the recess 2c of the main body 2. Yes. Therefore, when the process unit 6 is pushed out of the main body 2 by the pushing mechanism 21, the upper front portion of the process unit 6 contacts the protruding portion 3b of the open / close door 3 and lifts the protruding portion 3b upward. The engagement between the recess 2c of the main body 2 and the protrusion 3c of the open / close door 3 is released. As a result, the process unit 6 pushes the door 3 open and is pushed out of the main body 2. The open / close door 3 is held in the closed state by the main body 2 in the above-described configuration. However, the open / close door 3 may be simply held in the closed state by frictional force between the open / close door 3 and the main body 2 or electromagnetic means. Good.

  When the process unit 6 is pushed out of the main body 2 by the pushing mechanism 21, in order to stop the process unit 6 at a predetermined position, a projection 6a is formed on the bottom of the process unit 6 as shown in FIGS. The elastic protrusion 2d is formed in the main body 2 so as to be in contact with the protrusion 6a.

  FIG. 5 is a block diagram showing a schematic configuration of a circuit configuration that performs operation control of the present embodiment. The control unit 40 has a known function for controlling the image forming operation of the laser printer of this embodiment and a function for controlling the operation of the solenoid 30 of the extrusion mechanism 21 based on a predetermined control program. FIG. 5 shows only a portion related to the operation of the extrusion mechanism 21. The control unit 40 receives detection signals from the initial mounting sensor 33, the optical sensor 20, the paper feed sensor 34, and the paper discharge sensor 35, and based on these detection signals, controls the solenoid 30 of the push-out mechanism 21. To output an extrusion command.

  A configuration for determining the output timing of the extrusion command when the optical sensor 20 and the counting means are used together will be described with reference to the flowchart shown in FIG. When the initial mounting sensor 33 detects that an unused process unit 6 is first mounted (initial mounting) (YES in step S1), the counting means is reset (step S2). When it is not initially mounted, the counting means cumulatively counts the number of rotations of the developing roller 10 (step S3). The optical sensor 20 detects the presence or absence of the developer (step S4). If the developer is present, it is determined whether or not the cumulative count value of the counting means has reached a predetermined number of rotations (step S5). If the accumulated count value reaches the predetermined number of rotations (YES in step S5), a count determination signal is generated. When the optical sensor 20 detects the absence of developer, a detection signal is generated from the optical sensor 20 (YES in step S4). When one of the cumulative determination signal and the detection signal from the optical sensor 20 is generated, whether or not the paper P stays in the transport path is detected in the detection signals from the paper feed sensor 34 and the paper discharge sensor 35. Based on the determination (step S6). That is, when the paper feed sensor 34 detects that the leading edge of the paper P does not exist in the vicinity of the registration rollers 18 and 19, a paper non-detection signal is generated. When the paper discharge sensor 35 detects that the trailing edge of the paper P has passed through the paper discharge rollers 22 and 23, it generates a paper passage detection signal. When the control unit 40 receives the paper passage detection signal from the paper discharge sensor 35 in a state where the paper non-detection signal is continuously received from the paper feed sensor 34, the control unit 40 moves from the registration rotors 18 and 19 to the paper discharge rollers 22 and 23. It is determined that the paper P is not staying in the transport path. The determination of the control unit 40 is performed in step S6. When the control unit 40 determines that the paper P is not staying in the transport path (YES in step S6), an extrusion command is output to the solenoid 30 (step S7). By this push-out command, the solenoid 30 is excited, the movable shaft 31 is moved from the protruding position to the retracted position, and is released from the engagement with the stopper portion 29 of the piston member 27. As a result, the piston member 27 pushes out the process unit 6 by the urging force of the spring member 28, and the process unit 6 is pushed out of the main body by opening the opening / closing door 3. At this time, the process unit 6 is stopped at a predetermined position shown in FIG. 2 when the protrusion 6a contacts the elastic protrusion 2d for stopping.

  In this way, when the process unit 6 is pushed out of the device body 2 from the door 3, the operator can easily recognize that it is time to replace the process unit 6 by visually checking the state. In addition, the operator can easily take out and replace the extruded process unit 6.

  In the first embodiment, since the generation timing of the extrusion command is determined based on the detection signals from the three sensors of the optical sensor 20, the paper feed sensor 34, and the paper discharge sensor 35, The extrusion operation of the process unit 6 is executed only in a state where the paper P is not staying in the transport path. As a result, there is no possibility that a jam of the paper P occurs inside the main body during the extrusion operation of the process unit 6. When the image forming operation is stopped, the generation timing of the extrusion command may be determined based only on the developer remaining amount detection signal from the optical sensor 20.

  FIG. 7 shows a second embodiment of the present invention. Since the structure is basically the same as that of the first embodiment, the same parts are denoted by the same reference numerals to avoid redundant description, and only the differences will be described.

  In the first embodiment, the process unit 6 is detachably mounted inside the main body 2 as it is. However, in the second embodiment, the process unit 6 can be attached to and detached from a mounting table 36 that can move inside the main body 2. It is installed. The pushing mechanism 21 is arranged so as to act on the placing table 36, and the placing table 36 on which the process unit 6 is placed is pushed out from the open / close door 3. Although the pushing mechanism 21 directly acts on the mounting table 36, it directly acts on the process unit 6 instead of the mounting table to push the mounting table 36 on which the process unit 6 is mounted from the opening / closing door 3. It may be. Further, an elastic protrusion capable of contacting the mounting table 36 is provided in the main body like the elastic protrusion 2d of the first embodiment so that the process unit 6 is stopped at a predetermined position when it is pushed out. Also good.

  FIG. 8 shows a third embodiment of the present invention. Since the structure is basically the same as that of the first embodiment, the same parts are denoted by the same reference numerals to avoid redundant description and only differences will be described.

  In the third embodiment, the biasing device 24 and the solenoid 30 constituting the push-out mechanism 21 are arranged so as to act on different positions of the mounting table 36. That is, the movable shaft 31 of the solenoid 30 is disposed so as to engage with a stopper hole 36 a formed in the mounting table 36. Further, the piston member 27 pushed by the spring member 28 constituting the urging device 24 is in a state where it is always in contact with the mounting table 36 and urged. When the solenoid 30 is excited by the push command, the movable shaft 31 is disengaged from the stopper hole 36a, and the mounting table 36 is moved by the piston member 27.

  Here, the urging device 24 may be composed of only the spring member 28. In this case as well, the spring urging force of the spring member is always applied to the mounting table 36 or the process unit 6 mounted on the mounting table 36. You may make it act.

  FIG. 9 is a schematic sectional side view showing a fourth embodiment in which the present invention is embodied in a tandem color laser printer. In the fourth embodiment, the pushing mechanism has the same structure as that of the first embodiment shown in FIGS. Therefore, detailed description of the extrusion mechanism is omitted.

  The color laser printer 201 includes a visible image forming unit 204, a belt-like intermediate transfer body (ITB) 205, a fixing unit 208, a paper feeding unit 209, and a paper discharge tray 210b.

  The visible image forming unit 204 includes a developing device 251M as an image forming process unit for each visible image process using magenta (M), cyan (C), yellow (Y), and black (Bk) toners. 251C, 251Y, 251Bk, photosensitive drums 203M, 203C, 203Y, 203Bk, cleaning rollers 270M, 270C, 270Y, 270Bk, chargers 271M, 271C, 271Y, 271Bk, scanner units 272M, 272C, 272Y, 272Bk It has.

  Hereinafter, each of these components will be described in detail. First, the developing devices 251M, 251C, 251Y, and 251Bk are provided with developing rollers 252M, 252C, 252Y, and 252Bk. The developing rollers 252M, 252C, 252Y, and 252Bk are formed in a cylindrical shape using conductive silicone rubber as a base material, and further, a coating layer made of a resin or rubber material containing fluorine is formed on the surface.

  Each developing device 251M, 251C, 251Y, 251Bk is also provided with a supply roller 253M, 253C, 253Y, 253Bk. The supply rollers 253M, 253C, 253Y, and 253Bk are conductive sponge rollers, and are arranged so as to be in pressure contact with the developing rollers 252M, 252C, 252Y, and 252Bk by the elastic force of the sponge.

  Each of the developing devices 251M to 251Bk is provided with a layer thickness regulating blade 254M, 254C, 254Y, 254Bk. The layer thickness regulating blades 254M, 254C, 254Y, 254Bk are formed in a plate shape with stainless steel or the like and fixed to the developer case 255M, 255C, 255Y, 255Bk, and the tip is insulated silicone rubber or insulating Made of fluorine-containing rubber or resin. The tips of the layer thickness regulating blades 254M, 254C, 254Y, 254Bk are pressed against the developing rollers 252M, 252C, 252Y, 252Bk from below the developing rollers 252M, 252C, 252Y, 252Bk.

  Further, the developer stored in the developer boxes 255M, 255C, 255Y, and 255Bk is a positively charged nonmagnetic one-component developer. Each developer box 255M, 255C, 255Y, 255Bk contains magenta, cyan, yellow, and black developers.

  The cleaning rollers 270M, 270C, 270Y, and 270Bk are rollers made of an elastic material such as a conductive sponge, and are rubbed against the photosensitive drums 203M, 203C, 203Y, and 203Bk below the photosensitive drums 203M, 203C, 203Y, and 203Bk. Is configured to do. The cleaning rollers 270M, 270C, 270Y, and 270Bk are configured such that a negative voltage having a polarity opposite to that of the developer is applied by a power source (not shown), and the sliding rollers 270M, 270C, 270Y, and 270Bk are slid with respect to the photosensitive drums 203M, 203C, 203Y, and 203Bk. The developer on the intermediate transfer member 205 is reversely transferred to the photosensitive drum 203 and the developer on the photosensitive drums 203M, 203C, 203Y, and 203Bk is removed by the action of the frictional force and the electric field due to the voltage. Has been. In this embodiment, since a so-called cleanerless development method is employed, the residual developer once removed by the cleaning rollers 270M, 270C, 270Y, and 270Bk is again used in a predetermined cycle after the development process is completed. The photosensitive drums 203M, 203C, 203Y, and 203Bk are returned to each other, collected by the developing rollers 252M, 252C, 252Y, and 252Bk, and returned to the developing devices 251M, 251C, 251Y, and 251Bk of the respective colors.

  The chargers 271M, 271C, 271Y, and 271Bk are scorotron type chargers, and are more downstream than the cleaning rollers 270M, 270C, 270Y, and 270Bk in the rotation direction of the photosensitive drums 203M, 203C, 203Y, and 203Bk. The photosensitive drums 203M, 203C, 203Y, and 203Bk are opposed to the surface of the photosensitive drums 203M, 203C, 203Y, and 203Bk in a non-contact manner from below.

  The scanner units 272M, 272C, 272Y, and 272Bk are configured by known laser scanner units. The scanner units 272M, 272C, 272Y, and 272Bk are arranged so as to overlap the developing units 251M, 251C, 251Y, and 251Bk of the visible image forming unit 204 in the vertical direction, and the photosensitive drums 203M, 203C, 203Y and 203Bk. The chargers 271M, 271C, 271Y, and 271Bk are arranged so as to overlap with the chargers 271M, 271C, 271Y, and 271Bk in the horizontal direction. The surfaces of the photosensitive drums 203M, 203C, 203Y, 203Bk are exposed with laser light. The scanner units 272M, 272C, 272Y, and 272Bk irradiate the surface of the photosensitive drums 203M, 203C, 203Y, and 203Bk with laser light corresponding to the image data, and on the surfaces of the photosensitive drums 203M, 203C, 203Y, and 203Bk, An electrostatic latent image for each color is formed.

  The developer is positively charged, supplied from the supply rollers 253M, 253C, 253Y, and 253Bk to the developing rollers 252M, 252C, 252Y, and 252Bk, and formed into a uniform thin layer by the layer thickness regulating blades 254M, 254C, 254Y, and 254Bk. The Then, positive polarity (positive charging) electrostatics formed on the photosensitive drums 203M, 203C, 203Y, and 203Bk at the contact portions between the developing rollers 252M, 252C, 252Y, and 252Bk and the photosensitive drums 203M, 203C, 203Y, and 203Bk. A positively charged developer can be satisfactorily developed by the reversal development method for the latent image, and an extremely high quality image can be formed.

  The belt-shaped intermediate transfer member 205 is formed by forming a conductive sheet such as polycarbonate or polyimide in a belt shape. As shown in FIG. 9, the belt-like intermediate transfer member 205 is stretched between two drive rollers 260 and 262, and in the vicinity of the position facing the photosensitive drums 203M, 203C, 203Y, and 203Bk, the intermediate transfer roller is provided. 261M, 261C, 261Y, and 261Bk are provided. The movement direction of the surface of the intermediate transfer member 205 on the side facing the photosensitive drums 203M, 203C, 203Y, 203Bk is set to a direction of moving from the vertical direction upward to the downward direction as shown in FIG.

  A predetermined voltage is applied to the intermediate transfer rollers 261M, 261C, 261Y, and 261Bk so that the developer images formed on the photosensitive drums 203M, 203C, 203Y, and 203Bk are transferred to the intermediate transfer member 205. It is configured. In addition, a secondary transfer roller 263 is provided opposite to the roller 262 in the vertical direction with respect to the position where the developer image is transferred onto the sheet P, that is, the intermediate transfer member 205, and the secondary transfer roller 263. Also, a predetermined potential is applied. As a result, the four color developer images carried on the belt-like intermediate transfer member 205 are transferred onto the paper P.

  As shown in FIG. 9, a cleaning device 206 is provided on the side of the intermediate transfer member 205 opposite to the side facing the photosensitive drums 203M, 203C, 203Y, 203Bk. The cleaning device 206 includes a scraping member 265 and a case 266. The developer remaining on the intermediate transfer member 205 is scraped off by the scraping member 265 and stored in the case 266. Note that the cleaning device 206 is not operated during color correction.

  The fixing unit 208 includes a first heating roller 281 and a second heating roller 282, and the sheet P carrying the four color developer images is sandwiched between the first heating roller 281 and the second heating roller 282. The developer image is fixed on the paper P by heating and pressing while being conveyed.

  The paper feeding unit 209 is provided at the lowermost part of the apparatus, and includes a storage tray 291 that stores the paper P and a pickup roller 292 that feeds the paper P. The sheet feeding unit 209 has a predetermined timing with an image forming process by the scanner units 272M, 272C, 272Y, 272Bk, the developing devices 251M, 251C, 251Y, 251Bk, the photosensitive drums 203M, 203C, 203Y, 203Bk, and the intermediate transfer member 205. Thus, the paper P is supplied. The paper P supplied from the paper supply unit 209 is conveyed to the pressure contact portion between the intermediate transfer member 205 and the secondary transfer roller 263 by the conveyance roller pair 300.

  An upper surface cover 210 is provided at the top of the apparatus so as to be rotatable about a shaft 210a, and a part of the upper surface cover 210 constitutes a paper discharge tray 210b. The paper discharge tray 210b is provided on the paper discharge side of the fixing unit 208, and is configured to receive the paper P discharged from the fixing unit 208 and transported by the transport roller pairs 301, 302, and 303. Yes.

  Further, as shown in FIG. 9, the front opening / closing door 220 is configured to be rotatable about the shaft 220a in the direction of the arrow in FIG. By opening the front opening / closing door 220, the developing units 251M, 251C, 251Y, and 251Bk can be replaced. Here, spring members 221M, 221C, 221Y, 221Bk are provided at positions of the front opening / closing door 220 facing the developing devices 251M, 251C, 251Y, 251Bk, and when the front opening / closing door 220 is closed, the developing devices 251M, 251C. , 251Y and 251Bk are configured to press inward (to the left in FIG. 9).

  In the fourth embodiment, extrusion mechanisms 400M, 400C, 400Y, and 400Bk are provided corresponding to the developing units 251M, 251C, 251Y, and 251Bk, respectively, and each developing unit can be independently pushed out of the main body. it can. The detailed configuration of each extrusion mechanism is the same as that of the extrusion mechanism 21 of the first embodiment. Further, the front opening / closing door 220 has members (not shown) corresponding to the horizontal edge portion 3a, the protruding portion 3b and the protrusion 3c shown in FIG. 4 in the first embodiment, and each developing device is pushed out by the pushing mechanism. Sometimes, it is configured to be automatically released by engaging a part of the developing device. Although the front opening / closing door 220 is provided in common to the four developing devices, four front opening / closing doors may be provided independently for each developing device.

  Also in the fourth embodiment, the optical sensor 420M, 420C, 420Y, 420Bk is used as a developer remaining amount detecting means for detecting the remaining amount of developer stored in the developer boxes 255M, 255C, 255Y, 255Bk. It is provided as. The configuration of these photosensors is the same as that of the photosensor 20 of the first embodiment. In addition to the above optical sensor for detecting the remaining amount of developer, as a detecting means for detecting the replacement timing of the developing devices 251M, 251C, 251Y, and 251Bk corresponding to the image forming process unit, as in the first embodiment. A means for detecting or judging the lifetime of the components of the developing device may be employed.

  In order to detect that the sheet P does not stay in the sheet conveyance path between the first conveyance roller pair 300 and the final conveyance roller pair 303, as a paper feed presence / absence detection means on the upstream side of the conveyance roller pair 300. Paper feed sensor 430 is provided to detect whether or not the leading edge of the paper P has reached. A paper discharge sensor 440 as a paper passage detection unit is provided on the upstream side of the conveyance roller pair 303, and detects whether or not the rear end portion of the paper P has passed. These sensors 430 and 440 have the same configuration as the paper feed sensor 34 and the paper discharge sensor 35 of the first embodiment.

  FIG. 10 is a block diagram showing a schematic configuration of a circuit configuration for controlling the operation of the fourth embodiment. The control unit 450 has a known function for controlling the image forming operation of the color laser printer of this embodiment based on a predetermined control program, and a function for controlling the operation of the solenoid in the extrusion mechanisms 400M, 400C, 400Y, 400Bk. have. FIG. 10 shows only a portion related to the operation of the extrusion mechanism. The control unit 450 receives detection signals from the optical sensors 420M, 420C, 420Y, and 420Bk, the paper feed sensor 430, and the paper discharge sensor 440, and controls each solenoid in the push-out mechanism based on these detection signals. In response, an extrusion command is output. Each of the developing devices 251M, 251C, 251Y, and 251Bk includes a sensor having the same configuration as the initial mounting sensor 33 of the first embodiment, but is not illustrated.

  Next, the operation of the color laser printer 1 in the present embodiment as described above will be described. First, the photosensitive layers of the photosensitive drums 203M, 203C, 203Y, and 203Bk are uniformly charged by the chargers 271M, 271C, 271Y, and 271Bk. Next, these photosensitive layers are scanned by the scanner units 272M, 272C, 272Y, and 272Bk. Exposure is performed in correspondence with magenta, cyan, yellow, and black images. Then, the magenta developer 251M, the cyan developer 251C, the yellow developer 251Y, and the black developer 251Bk form magenta developers on the electrostatic latent images formed on the photosensitive layers 203M, 203C, 203Y, and 203Bk, respectively. Then, a cyan developer, a yellow developer, and a black developer are attached, and magenta, cyan, yellow, and black colors are developed. The magenta, cyan, yellow, and black developer images formed in this way are once transferred onto the surface of the intermediate transfer member 205.

  Next, the developer remaining on the photosensitive drums 203M, 203C, 203Y, and 203Bk after the transfer is temporarily held by the cleaning rollers 270M, 270C, 270Y, and 270Bk. The developer images of the respective colors are formed with a slight time difference in accordance with the moving speed of the intermediate transfer member 205 and the positions of the photosensitive drums 203M, 203C, 203Y, and 203Bk. The developer image is transferred so as to be superimposed on the intermediate transfer member 205.

  The four color developer images formed on the intermediate transfer member 205 as described above are formed on the sheet P supplied from the paper feeding unit 209 at the pressure contact position between the secondary transfer roller 263 and the intermediate transfer member 205. Transcribed. The developer image is fixed on the paper P in the fixing unit 208 and discharged onto the paper discharge tray 210b. As described above, a four-color image is formed.

  When any one of the optical sensors 420M, 420C, 420Y, and 420Bk detects that the developer has decreased to a predetermined amount or less while the color image is being formed, a developer remaining amount detection signal is generated. . When the paper feed sensor 430 detects that the leading edge of the paper P does not exist in the vicinity of the conveyance roller pair 300, the paper feed sensor 430 generates a paper no detection signal. When the paper discharge sensor 440 detects that the trailing edge of the paper P has passed through the last-stage transport roller pair 303, the paper discharge sensor 440 generates a paper passage detection signal. When the control unit 450 continuously receives the paper non-detection signal from the paper feed sensor 430 and receives the paper passage detection signal from the paper discharge sensor 440, the control unit 450 transfers the conveyance path from the conveyance roller pair 300 to the conveyance roller pair 303. It is determined that the paper P is not staying inside. When the controller 450 receives the developer remaining amount detection signal from one of the optical sensors and determines that the paper P is not staying in the transport path as described above, the controller 450 issues an extrusion command to the four commands. Output to the corresponding solenoid in the extrusion mechanism. The solenoid is excited by this pushing command. As a result, the developing device in which the remaining amount of the developer is equal to or less than the predetermined amount is pushed out by the urging force of the spring member in the pushing mechanism, and is pushed out of the main body by opening the front opening / closing door 220. At this time, the developing device is stopped at a predetermined position by contacting an elastic protrusion for stopping provided in the main body.

  As described above, when any of the developing devices 251M, 251C, 251Y, and 251Bk as the image forming process unit is pushed out of the main body of the apparatus from the front opening / closing door 220, the operator visually checks the state and It is possible to easily recognize whether it is time to replace the color developer, and the operator can easily take out and replace the extruded developer.

  In the fourth embodiment, since the generation timing of the extrusion command is determined based on the detection signals from the optical sensors 420M, 420C, 420Y, 420Bk, the paper feed sensor 430, and the paper discharge sensor 440, the paper Only in a state where the sheet P is not staying in the P transport path, the push-out operation of the developing unit which is an image forming process unit is executed. Thus, there is no possibility that the jam of the paper P occurs inside the main body during the pushing operation of the developing device. Instead of this method, the generation timing of the extrusion command is determined based only on the developer remaining amount detection signals from the optical sensors 420M, 420C, 420Y, and 420Bk during the period when the color image forming operation is stopped. A configuration may be adopted.

1 is a side sectional view of a laser printer according to a first embodiment of the present invention. It is a sectional side view of a laser printer at the time of process unit exchange of the 1st example. It is an enlarged view of the extrusion mechanism of a 1st Example. It is a partial sectional side view of the holding mechanism and release member of the first embodiment. It is a control block diagram of a 1st example. It is a flowchart for extrusion command output timing determination. It is a partial sectional side view of the 2nd Example of this invention. It is a partial expanded side sectional view of the 3rd example of the present invention. It is a sectional side view of the color laser printer of the 4th Example of this invention. It is a control block diagram of a 4th example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Laser printer 2 Equipment main body 2c Recessed part 3 Opening / closing door 3a Edge part 3b Protruding part 3c Protrusion 4 Paper transport mechanism 5 Scanner unit 6 Process unit 7 Fixing unit 8 Photosensitive drum 9 Charger 10 Developing roller 11 Developer box 12 Transfer roller 13 Developing Agent supply roller 15 Support shaft 16 Cassette 17 Pickup roller 18, 19 Registration roller 20 Optical sensor 21 Extrusion mechanism 22, 23 Paper discharge roller 24 Biasing device 25 Opening portion 26 Bottomed cylindrical body 27 Piston member 28 Spring member 29 Stopper portion 30 Solenoid 31 Movable shaft 32 Spring part 33 Initial mounting sensor 34 Paper feed sensor 35 Paper discharge sensor 36 Mounting table 40 Control part P Paper 220 Front open / close door 251M, 251C, 251Y, 251Bk Developer 400M, 400C, 400Y, 400Bk Extrusion mechanism 420M, 20C, 420Y, 420Bk light sensor 430 feeding sensor 440 discharge sensor 450 control unit

Claims (12)

In an image forming apparatus having a replaceable image forming process unit and an opening / closing door that opens and closes for replacement of the image forming process unit,
Detecting means for detecting the replacement time of the image forming process unit;
An extruding means for opening the open / close door and extruding the image forming process unit from the mounted state to the outside of the apparatus body;
An image forming apparatus comprising: a control unit that performs an extrusion operation of the extrusion means based on a detection result of the detection means. A registration roller, a transfer unit that transfers an image onto a sheet on the downstream side of the registration roller, a sheet discharge roller that discharges the sheet onto which the image has been transferred, a replaceable image forming process unit, and an image forming process unit In an image forming apparatus having an opening / closing door that opens and closes for replacement,
Detecting means for detecting the replacement time of the image forming process unit;
Paper feed presence / absence detecting means for detecting the presence or absence of paper in the registration roller;
Paper passage detection means for detecting passage of the rear end of the paper in the paper discharge roller;
An extruding means for opening the open / close door and extruding the image forming process unit from the mounted state to the outside of the apparatus body;
An image forming apparatus comprising: a control unit that causes the pushing-out operation of the pushing-out means based on the detection result of each of the detecting means. The image forming process unit has a developer accommodating portion,
3. The image forming apparatus according to claim 2, wherein the detecting means for detecting the replacement timing of the image forming process unit is a remaining amount detecting means for detecting a remaining amount of the developer in the developer accommodating portion.   The remaining amount detecting means detects that the remaining amount of the developer in the developer accommodating portion has decreased to a predetermined amount, and the paper feeding presence / absence detecting means detects that there is no sheet in the registration roller. 4. The control device according to claim 3, wherein when the paper passage detecting means detects that the paper trailing edge has passed through the paper discharge roller, the control portion causes the pushing means to perform a pushing operation. The image forming apparatus described.   The image forming process provided between the open / close door and the device main body, and having a holding mechanism for holding the closed state of the open / close door, wherein the push-out means is pushed out of the device main body from the mounted state. The image forming apparatus according to claim 1, further comprising a release member that engages with a part of the unit and releases the holding by the holding mechanism.   6. The image forming apparatus according to claim 1, wherein the push-out means abuts on the image forming process unit to directly apply push force to the image forming process unit.   The image forming process unit is mounted on a mounting table movable from a mounted state to a position outside the apparatus body, and the pushing force of the pushing means is applied to the image forming process unit or the mounting table. Item 7. The image forming apparatus according to any one of Items 1 to 6.   The push-out means comprises a biasing means for generating a biasing force acting on the image forming process unit or the mounting table, and a holding means for holding the image forming process unit or the mounting table in a predetermined position, and the control unit 8. The urging means pushes out the image forming process unit or the mounting table by the urging force when the holding means releases the holding at the predetermined position by an extruding command. The image forming apparatus according to claim 1.   The biasing means includes a bottomed cylindrical body that has an opening at one end and is fixed to the device body, a piston member that is inserted into the bottomed cylindrical body and has one end protruding from the opening, and the piston A spring member disposed between the other end of the member and the bottom of the bottomed cylindrical body and biasing the piston member toward the image forming process unit; The piston member applies an urging force to the image forming process unit or the mounting table when the holding means is engaged and held at a predetermined position and the engagement and holding is released by an extrusion command of the control unit. The image forming apparatus according to claim 8.   The holding means is composed of a solenoid mounted on the device body, and the movable shaft of the solenoid is engaged with a stopper portion formed on the protruding end portion of the piston member to hold the piston member in a predetermined position, and the control And a biasing force of the piston member is applied to the image forming process unit or the table. Item 10. The image forming apparatus according to Item 9.   The holding means is engaged with a mounting table on which the image forming process unit is mounted, and the biasing means is always in contact with the image forming process unit or the mounting table to apply an extrusion force, and the holding means is 9. The image forming apparatus according to claim 8, wherein when the engagement is released from the mounting table by an extrusion command from the control unit, the urging unit pushes the image forming process unit by the urging force. In an image forming apparatus having a plurality of replaceable image forming process units provided for each color and an opening / closing door that opens and closes for replacement of the image forming process units.
Detecting means for detecting the replacement time of each of the image forming process units;
A plurality of pushing means provided corresponding to each image forming process unit to open the door and push the image forming process unit from the mounted state to the outside of the apparatus body;
An image forming apparatus comprising: a control unit that performs an extrusion operation of each of the extrusion means based on a detection result of the detection means.

Images