JP5137774B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus such as a copying machine, a printer, and a facsimile.

  More specifically, the present invention relates to a tandem type (in-line type) image forming apparatus in which a plurality of process cartridges are arranged along the moving direction of a circulating intermediate transfer member to form an image on a recording medium.

  In the present invention, the image forming apparatus includes an electrophotographic image forming apparatus, an electrostatic recording image forming apparatus, a magnetic recording image forming apparatus, and the like.

  The electrophotographic image forming apparatus uses an electrophotographic photosensitive member as an image carrier, applies an electrophotographic image forming process to the electrophotographic photosensitive member, forms an electrostatic latent image, and forms an image on a recording medium. For example, an electrophotographic copying machine, an electrophotographic printer (such as an LED printer or a laser beam printer), an electrophotographic facsimile apparatus, and an electrophotographic word processor are included.

  The electrostatic recording image forming apparatus uses an electrostatic recording dielectric as an image carrier, applies an electrostatic recording image forming process to the electrostatic recording image forming process, forms an electrostatic latent image, and forms an image on a recording medium. .

  The magnetic recording image forming apparatus uses a magnetic recording magnetic material as an image carrier, applies a magnetic recording image forming process to the magnetic recording image, forms a magnetic latent image, and forms an image on a recording medium.

  The process cartridge includes at least an image carrier on which a latent image is formed, a developing member that develops the latent image formed on the image carrier with a developer, and a developer storage for storing the developer. And a cartridge. This is made detachable from the main body of the image forming apparatus. According to the process cartridge system, the maintenance of the image forming apparatus can be performed by the user himself / herself without depending on the service person, so that the operability can be greatly improved at each stage. The apparatus main body is an image forming apparatus portion other than the process cartridge.

  One of the cases where the process cartridge is exchanged is a shortage of developer (toner) in the process cartridge. In this case, in order to inform the user of the developer remaining amount information in advance and facilitate smooth replacement, the developer remaining amount in the process cartridge is detected by the developer remaining amount detecting means.

  Specifically, Patent Document 1 discloses the following configuration. An image forming device (process cartridge) that stores the developer, a light emitting unit that emits light and a light receiving unit that receives light are disposed on the opposite side of the image forming device. A sensor is provided for outputting a signal corresponding to the amount of light received by the light receiving unit and detecting the remaining amount of the developer stored in the image forming apparatus.

  On the other hand, as described above, in the tandem (in-line type) image forming apparatus using the intermediate transfer member, the image detection means for detecting the image formed on the intermediate transfer member is arranged. This image detecting means is provided for correcting the relative shift of each color of each process cartridge. That is, the control circuit unit of the image forming apparatus forms a correction image (patch) on the intermediate transfer member at a timing such as when a process cartridge is replaced with a new one or when a predetermined number of prints are completed. And the control which corrects the relative shift | offset | difference of each color is performed by detecting the image with an image detection means.

In such an image forming apparatus, as a process cartridge presence / absence detecting means for detecting whether or not a process cartridge is present in the apparatus main body, the developer remaining amount detecting means and the image detecting means are used. Is known. According to this process cartridge presence / absence detecting means, since a mechanism necessary for the image forming apparatus is used in a normal use state, it is necessary to add a special part for detecting the presence or absence of the process cartridge in the image forming apparatus. There is an advantage that there is no. That is, the dedicated process cartridge presence / absence detecting means may not be provided.
JP 2007-47413 A JP 2006-154519 A

  However, in the configuration in which the process cartridge is disposed between the developer remaining amount detecting means and the intermediate transfer member, the following problems have been pointed out in the conventional process cartridge presence / absence detecting means. That is, in the state where the process cartridge is not inserted in the apparatus main body, the light emitted from the light emitting portion of the developer remaining amount detecting means hits the intermediate transfer body and is reflected on the surface of the intermediate transfer body and reflected by the developer remaining amount detecting means. There is a case where a state of entering the light receiving portion of the camera is generated. For this reason, there is a possibility that the control circuit unit may erroneously detect that the process cartridge is in the apparatus main body.

  In order to prevent such a problem from occurring, a part is added between the developer remaining amount detecting means and the intermediate transfer member so that the light from the light emitting portion of the developer remaining amount detecting means is not reflected by the light receiving portion. This method is common. However, this increases the cost of adding parts. In addition, there is no space for adding parts, which leads to an increase in the size of the apparatus in order to secure the space.

  Therefore, the present invention solves the above-described problem in the image forming apparatus that detects whether or not there is a process cartridge in the apparatus main body using the optical developer remaining amount detecting means and the image detecting means as described above. It will be solved. That is, an object of the present invention is to improve the reliability of the apparatus by preventing erroneous detection of the presence / absence of the process cartridge without adding parts even when the process cartridge is not inserted in the apparatus main body.

  In order to achieve the above object, a typical configuration of an image forming apparatus according to the present invention includes at least an image carrier on which a latent image is formed and a latent image formed on the image carrier with a developer. A developing member for storing the developer, and a developer storage portion for storing the developer. The image forming apparatus is guided by guide means disposed in a mounting portion of the apparatus main body with respect to the apparatus main body. A plurality of possible process cartridges, an intermediate transfer member to which a developed image formed on an image carrier of the process cartridge is primarily transferred, and a second image transfer image formed on the intermediate transfer member to a recording medium. Next transfer means, developer remaining amount detecting means provided for each of the plurality of process cartridges for optically detecting the remaining amount of developer in the developer accommodating portion, and development formed on the intermediate transfer member Image detection to detect images An image forming apparatus that detects the presence or absence of the process cartridge with respect to the apparatus main body using the developer remaining amount detecting unit and the image detecting unit. A detection unit disposed on the apparatus main body side and a detected unit disposed on the process cartridge side and positioned opposite to the detection unit when the process cartridge is mounted on the apparatus main body. The detection unit has a light emitting part and a light receiving part in which light beams are directed toward the intermediate transfer member, and the guide means is at least between the detection unit and the intermediate transfer member. In a state where the guide member is positioned and the process cartridge is not mounted on the apparatus main body, a part of the guide member is Part or all of the optical path of the light beam emitted from the serial light emitting portion, characterized in that shields against the intermediate transfer body.

  According to the present invention, even when the process cartridge is not inserted into the apparatus main body, it is possible to prevent erroneous detection of the presence or absence of the process cartridge and improve the reliability of the apparatus without adding any parts.

[Example 1]
<< Overall Configuration of Image Forming Apparatus >>
FIG. 1 is a schematic longitudinal sectional front view of an image forming apparatus 100 in this embodiment, and shows an image forming operation state. FIG. 2 is a partially enlarged view of FIG. FIG. 3 is an external perspective view of the image forming apparatus 100 in a state in which a door (opening / closing member) 21 for opening and closing the apparatus main body 100A is closed. FIG. 4 is an external perspective view of the image forming apparatus 100 showing a state in which the door 21 is opened and the first process cartridge 7a is inserted into or pulled out from the apparatus main body 100A.

  Here, with respect to the image forming apparatus 100 of the present embodiment, the front side or the near side is the side on which the door 21 is disposed, and is the upstream side in the mounting direction of the process cartridge (hereinafter referred to as cartridge) 7. The back side or the back side is the opposite side and the downstream side in the mounting direction of the cartridge 7. The front-rear direction is a direction from the back side to the front side (front direction) and the opposite direction (rear direction). Left and right are left or right when the image forming apparatus 100 is viewed from the front side. The left-right direction is a direction from left to right (left direction) and the opposite direction (right direction). The image forming apparatus main body (hereinafter, referred to as “apparatus main body”) 100 </ b> A is a configuration obtained by removing the cartridge 7 from the configuration of the image forming apparatus 100. Further, with respect to the cartridge 7 or its constituent members, or the constituent members on the apparatus main body side, the longitudinal direction refers to the axial direction of the electrophotographic photosensitive drum (image carrier: hereinafter referred to as drum) 1 of the cartridge 7 or its axis. The direction is parallel to the direction. The short direction is a direction orthogonal to the axial direction of the drum 1. With respect to the cartridge 7, in the longitudinal direction, the side to which driving is transmitted from the apparatus main body 100A side is referred to as a driving side, and the opposite side is referred to as a non-driving side.

  The image forming apparatus 100 of the present embodiment is a four-color full-color laser beam printer (color image forming apparatus) using an electrophotographic process. That is, an image is recorded on a sheet-like recording medium S (paper, OHP sheet, label, etc.) based on an electrical image signal input to a control circuit unit (control means: CPU) A from an external host device B such as a personal computer or an image reader. Form. The control circuit unit A exchanges various types of electrical information with the external host device B and the operation unit C, and comprehensively controls the image forming operation of the image forming apparatus 100 according to a predetermined control program and reference table. .

  In the image forming apparatus 100, a plurality of cartridges, that is, the first to fourth cartridges 7 (7a, 7b, 7c, 7d) in the image forming apparatus of this embodiment can be detached from the apparatus main body 100A. It is a method that is used by mounting. Each cartridge 7 is independently opened to the cartridge mounting portion 22 (22a, 22b, 22c, 22d) in the apparatus body by opening the door 21 of the apparatus body 100A as shown in FIG. 4 and opening the front side of the apparatus body 100A. It can be attached and detached. Reference numeral 21 a denotes a handle disposed on the front door 21. The cartridge mounting portions 22 are arranged in the horizontal direction from the left side to the right side.

  Each cartridge mounting portion 22 is provided with a plurality of guide rails that are long in the front-rear direction as guide means (guide members) for guiding the cartridge 7 when it is attached to and detached from the apparatus main body 100A. In FIG. 1 and FIG. 2, only the upper guide rail 9 (9a, 9b, 9c, 9d) of the plurality of guide rails is shown.

  Each cartridge 7 has the same electrophotographic process mechanism. Each cartridge 7 of this embodiment includes a drum 1 and a cleaner unit 6 having a charging roller (charging means) 2 and a cleaning member (cleaning means) 41 as process means acting on the drum 1, and a developing unit (developing means). 4.

  In the image forming apparatus of this embodiment, the first cartridge 7 a contains a yellow (Y) developer (hereinafter referred to as toner) in the toner storage chamber of the developing unit 4. The second cartridge 7 b contains magenta (M) toner in the toner containing chamber of the developing unit 4. The third cartridge 7 c stores cyan (C) toner in the toner storage chamber of the developing unit 4. The fourth cartridge 7 d stores black (K) toner in the toner storage chamber of the developing unit 4.

  A rotational driving force is transmitted from the apparatus main body 100A side to each cartridge 7 mounted at a position where an image can be formed, and the drum 1 is rotationally driven in a clockwise direction indicated by an arrow at a predetermined speed. Each cartridge 7 is supplied with a predetermined bias (charging bias, developing bias, etc.) from the apparatus main body 100A side.

  In the apparatus main body 100A, a laser scanner unit 3 as image information exposure means for the drum 1 of each cartridge 7 is disposed below each cartridge mounting portion 22 (vertically below each cartridge).

  Further, in the apparatus main body 100A, an intermediate transfer belt unit 50 is provided above the cartridge mounting portion 22 (vertically above each cartridge). The unit 50 includes a drive roller 10 disposed on the right side, a tension roller 11 disposed on the left side, and an intermediate transfer belt member (hereinafter referred to as a belt) as an intermediate transfer member suspended around both rollers. 5). Also, first to fourth primary transfer rollers 12 (12a, 12b, 12c, 12d) facing the drum 1 of each cartridge 7 are arranged in parallel inside the belt 5 with the rotational axis direction being the front-rear direction. It is installed. In a state where each cartridge 7 is mounted at a position where image formation is possible, the upper surface portion of the drum 1 of each cartridge 7 is in contact with the lower surface of the descending belt portion of the belt 5 at the position of each primary transfer roller 12. The contact portion is the primary transfer portion T1. The belt 5 is circulated and moved at a speed corresponding to the rotational speed of the drum 1 in the counterclockwise direction indicated by the arrow R by the drive roller 10 with the descending belt portion in contact with the upper surface portion of the drum 1 of each cartridge 7. The A predetermined primary transfer bias is applied to each primary transfer roller 12 at a predetermined control timing. A secondary transfer roller 18 is disposed outside the belt bending portion of the driving roller 10. A contact portion between the belt 5 and the secondary transfer roller 18 is a secondary transfer portion T2. A predetermined secondary transfer bias is applied to the secondary transfer roller 18 at a predetermined control timing. A transfer belt cleaning device 23 is disposed outside the belt bent portion of the tension roller 11.

  A recording medium feeding device 13 is disposed below the apparatus main body 100A. The recording medium feeding device 13 has a feeding cassette 24 containing a recording medium (transfer material) S, and a roller pair of a feeding roller 91 and a retard roller 91a. Further, on the right side in the apparatus main body 100A, a recording medium conveying means is provided from the recording medium feeding apparatus 13 to the upper part of the apparatus main body. The recording medium transport unit includes a registration roller pair 17, a transport path 15, a secondary transfer portion T 2, a fixing unit (fixing unit) 14, and a discharge roller pair 19. The upper surface of the apparatus main body 100A is a discharge tray 20.

  The feeding cassette 24 is taken in and out of the apparatus main body 100A by front access. In FIG. 3, a handle 24 a is provided in the feeding cassette 24. That is, the feeding cassette 24 can be pulled out to the front side of the apparatus main body 100A as indicated by an arrow F in FIG. The user removes the feeding cassette 24 from the apparatus main body 100A and sets the recording medium S in the feeding cassette. By inserting the feeding cassette 24 into the apparatus main body 100A as indicated by an arrow G, the replenishment of the recording medium is completed.

  A manual feed unit 51 is provided on the right side surface of the apparatus main body 100A. The manual feed unit 51 opens the right side door 52 of the apparatus main body 100A, and the manual feed tray (multipurpose tray) 53 is pulled out. The recording medium S is set on the manual feed tray 53. In the manual feed mode, the recording medium S on the manual feed tray 53 is fed out by the feed roller 54, separated by the separation feed unit 55, and conveyed to the registration roller pair 17. The manual feed tray 53 is stored in the apparatus main body 100A by closing the right side door 52 with respect to the apparatus main body 100A when not in use. A handle 52 a is disposed on the right side door 52.

  The operation for forming a full-color image is as follows. The control circuit unit A starts an image forming operation of the image forming apparatus based on the print start signal. That is, the drums 1 of the first to fourth cartridges 7 (7a, 7b, 7c, and 7d) are rotationally driven at a predetermined speed in the clockwise direction of the arrow in accordance with the image formation timing. The belt 5 is also rotationally driven at a speed corresponding to the speed of the drum 1 in the counterclockwise direction indicated by the arrow R (forward direction with respect to the rotation of the drum). The laser scanner unit 3 is also driven. In synchronization with this drive, in each cartridge 7, the surface of the drum 1 is uniformly charged to a predetermined polarity and potential by the charging roller 2 to which a predetermined charging bias is applied. The laser scanner unit 3 scans and exposes the surface of each drum 1 with a laser beam L (La, Lb, Lc, Ld) modulated according to image information signals of each color of Y, M, C, and K. The laser beams L are emitted upward from first to fourth window portions 81 (81a, 81b, 81c, 81d) provided on the upper surface plate 80 of the laser scanner unit 3, respectively. The laser beam L output from the laser scanner unit 3 enters the corresponding cartridge 7 from the lower laser beam incident opening 63 and irradiates the lower surface of the drum 1. As a result, an electrostatic latent image corresponding to the image information signal of the corresponding color is formed on the surface of each drum 1. The formed electrostatic latent image is developed as a toner image (developed image) by a developing roller (developing member) 42 of the developing unit 4.

  By the electrophotographic image forming process operation as described above, a Y color toner image corresponding to the yellow component of the full color image is formed on the drum 1 of the first cartridge 7a, and this toner image is the primary transfer portion T1 of the cartridge 7a. 1 is primarily transferred onto the belt 5. An M-color toner image corresponding to the magenta component of the full-color image is formed on the drum 1 of the second cartridge 7b, and the Y-color that has already been transferred onto the belt 5 at the primary transfer portion T1 of the cartridge 7b. The toner image is primarily transferred onto the toner image. A C-color toner image corresponding to the cyan component of the full-color image is formed on the drum 1 of the third cartridge 7c, and this toner image is already transferred onto the belt 5 at the primary transfer portion T1 of the cartridge 7c. Superimposed on the + M color toner image is primarily transferred. A K-color toner image corresponding to the black component of the full-color image is formed on the drum 1 of the fourth cartridge 7d, and this toner image is already transferred onto the belt 5 in the primary transfer portion T1 of the cartridge 7d. The toner image is primary-transferred superimposed on the + M color + C color toner image. Each of the first to fourth primary transfer rollers 12 (12a, 12b, 12c, and 2d) is applied with a primary transfer bias having a predetermined potential that is opposite to the charging polarity of the toner at a predetermined control timing.

  In this way, a four-color full-color unfixed toner image of Y color + M color + C color + K color is synthesized and formed on the moving belt 5. This unfixed toner image is conveyed by the subsequent rotation of the belt 5 and reaches the secondary transfer portion T2.

  In each cartridge 7, the surface of the drum 1 after the primary transfer of the toner image to the belt 5 is cleaned by wiping and removing the primary transfer residual toner by a cleaning member (cleaning blade) 41 included in the cleaning unit 6. Provided to the process. The removed toner is collected in a waste toner container in the cleaning unit 6.

  On the other hand, the recording medium S in the feeding cassette 24 is fed by one sheet by the feeding roller 91 and the retard roller 91a at a predetermined control timing, and is conveyed to the registration roller pair 17. In the manual feed mode, the recording medium S on the manual feed tray 53 is fed by the feed roller 54, separated and fed by the separation feeding unit 55, and conveyed to the registration roller pair 17. The recording medium S is conveyed by the registration roller pair 17 through the conveyance path 15 to the secondary transfer unit T2 at a predetermined control timing. The secondary transfer roller 18 is applied with a secondary transfer bias having a predetermined potential opposite to the toner charging polarity at a predetermined control timing. As a result, in the process in which the recording medium S is nipped and conveyed by the secondary transfer portion T2, the four-color superimposed toner images on the belt 5 are secondarily transferred to the surface of the recording medium S in sequence. The recording medium S that has exited the secondary transfer portion T2 is separated from the belt 5 and conveyed to the fixing unit 14 that is a fixing unit, and the toner image is fixed on the recording medium S. The recording medium S exiting the fixing unit 14 is discharged to a discharge tray 20 by a discharge roller 19.

  The fixing unit 14 fixes the image formed on the recording medium S by applying heat and pressure. The fixing unit 14 has a cylindrical fixing belt 14a. The fixing belt 14a is disposed inside thereof and is guided by a belt guide member (not shown) to which heat generating means such as a heater is bonded. An elastic pressure roller 14b sandwiches the fixing belt 14a and forms a fixing nip portion N having a predetermined width with a predetermined pressure contact force with a belt guide member. The pressure roller 14b is rotationally driven by the driving means, and the cylindrical fixing belt 14a rotates accordingly, and the fixing belt 14a is heated by the internal heater. In a state where the fixing nip N rises to a predetermined temperature and is adjusted in temperature, the recording medium S on which an unfixed toner image is formed from the secondary transfer unit T2 faces the fixing nip N and the image surface faces the fixing belt surface. Introduced. The recording medium S is nipped and conveyed through the fixing nip N together with the fixing belt 14a with the image surface closely contacting the outer surface of the fixing belt 14a at the fixing nip N. In the process in which the sheet S is nipped and conveyed through the fixing nip N together with the fixing belt 14a, the heat of the heater in the fixing belt 14a is heated, and the unfixed toner image on the recording medium S is heated and fixed. The recording medium S on which the image has been fixed is discharged to a paper discharge tray 20 by a paper discharge roller pair 19.

  Alternatively, the recording medium S on which the image has been fixed can be transported to the recirculation transport path 16 for printing on the second surface of the recording medium S without being ejected to the paper ejection tray 20, and duplex printing can be performed.

  The secondary transfer residual toner remaining on the surface of the belt 5 after the secondary transfer of the toner image to the recording medium S is removed from the belt surface by the transfer belt cleaning device 23, and the cleaned belt surface is subjected to the next image forming process. The The toner removed by the transfer belt cleaning device 23 passes through a waste toner conveyance path (not shown), is conveyed to a waste toner collection container (not shown) disposed on the back surface of the device, and is collected.

  In the image forming apparatus of the present embodiment, the drum 1 of each cartridge 7 is charged to a predetermined negative potential by the charging roller 2 and then an electrostatic latent image is formed by the laser scanner unit 3. The electrostatic latent image is developed by the developing unit 4 with toner having a negative charging polarity (negative toner) and is developed as a toner image.

  Here, an image detection means 70 for detecting an image drawn on the surface of the belt 5 is disposed on the upstream side of the secondary transfer portion T2 in the belt rotation direction so as to face the belt 5. In this embodiment, an image sensor that optically detects an image is used. The control circuit unit A corrects the relative displacement between the colors of the cartridges 7a, 7b, 7c, and 7d, such as when a cartridge is replaced with a new one, when a certain number of prints are completed, and so on. A correction image (patch) is formed on the belt 5. Then, the image detection unit 70 detects the image to perform control for correcting the relative shift between the colors.

<Process cartridge>
The process cartridge 7 in this embodiment will be described with reference to FIGS. Each of the first to fourth cartridges 7 (7a, 7b, 7c, 7d) is different from Y, M, C, and K in the color of the toner stored in the toner storage chamber of the developing unit 4, respectively. It is the same configuration. 5A is an external perspective view of the cartridge 7 viewed from the front side (non-driving side) in the mounting direction K, and FIG. 5B is an external perspective view of the cartridge 7 viewed from the back side (driving side) in the mounting direction K. FIG. 4C is an external perspective view of the cartridge 7 viewed from the developing unit 4 side. FIG. 6 is a partially enlarged cross-sectional view of the cartridge 7 mounted at a position where an image can be formed in the apparatus main body 100A and the periphery thereof.

  The cartridge 7 is an assembly whose longitudinal direction is the direction O-O of the drum 1, and includes a cleaning unit 6 and a developing unit 4.

  The cleaning unit 6 includes the drum 1 and at least one of process means excluding the developing means among the process means acting on the drum 1. In the present embodiment, a drum 1 and a charging roller (charging means) 2 and a cleaning member (cleaning means) 41 as process means acting on the drum 1 are provided. The drum 1 is rotatably attached to the cleaning frame body 43 of the cleaning unit 6 via bearing members (flanges) 44 and 45 on the front side and the back side. The drum 1 is configured, for example, by applying an organic photoconductor (OPC) to the outer peripheral surface of an aluminum cylinder. A charging roller (conductive roller) 2 and a cleaning member (cleaning blade) 41 are arranged on the periphery of the drum 1. The charging roller 2 is kept in contact with the drum 1 with a predetermined pressing force, and rotates following the rotation of the drum 1. The cleaning member 41 is kept in contact with the drum 1 with a predetermined pressing force. The residual toner removed from the surface of the drum 1 by the cleaning member 41 falls into the removed toner chamber 43a. A drive input coupling (drive receiving portion) 46 is provided at the end of the cleaning frame 43 as viewed from the cartridge mounting direction.

  The developing unit 4 is a unit of developing means for developing the electrostatic latent image formed on the drum as a toner image. The developing frame 47 of the developing unit 4 is in contact with the drum 1 and a toner storage chamber (developer storage unit / developer container) 47a that stores toner (not shown) as a developer, and rotates in the direction of arrow H. And a developing chamber 47b in which a developing roller 42 is disposed. The development chamber 47b is disposed above the toner storage chamber 47a, and the toner storage chamber 47a and the development chamber 47b communicate with each other through an opening 47c positioned above the toner storage chamber 47a. A toner supply roller 48 as a developer supply member that rotates in the direction of arrow I in contact with the development roller 42 is disposed on the circumference of the development roller 42.

  The toner storage chamber 47a is provided with a toner stirring member 61 that is rotatably supported to stir the stored toner and to send the toner through the opening 47c to the toner supply roller 48 of the development chamber 47b. ing. The toner stirring member 61 includes a shaft member 61a and a flexible resin stirring sheet 61b attached to the shaft member 61a at one end for stirring and transporting the toner. The toner stirring member 61 is driven to rotate at a predetermined speed in the arrow M direction in accordance with the image forming operation.

  Further, on the outer wall surface 47d of the toner accommodating chamber 47a of each cartridge 7, a detected unit 30 (30a) constituting first to fourth developer remaining amount detecting means 25 (25a, 25b, 25c, 25d) described later. · 30b · 30c · 30d) are arranged.

  The developing device frame 47 of the developing unit 4 is coupled to the cleaning frame member 43 of the cleaning unit 6 so as to be rotatable about a support shaft 62. When the image of the cartridge 7 is formed, the developing unit 4 causes the developing roller 42 to move to the drum 1 around the support shaft 62 by a tension force of a pressure spring (not shown) provided between the developing unit 4 and the cleaning unit 6. It is urged to rotate in the abutting direction. As a result, the developing roller 42 is held in contact with the drum 1 with a predetermined pressing force. At the time of non-image formation, the developing unit 4 is held in a state where the developing roller 42 is rotated about the support shaft 62 in a direction away from the drum 1 against the pressure spring (development). The unit 4 is brought into contact with and separated from the drum 1). A gap between the cleaning unit 6 and the developing unit 4 is a slit opening 63 serving as a laser beam incident opening.

  In the positioning state in which the cartridge 7 is inserted into the mounting portion 22 of the apparatus main body 100A and is mounted at a position where image formation is possible, the upper surface of the drum 1 is in contact with the lower surface of the descending belt portion of the belt 5. A primary transfer portion T1 is formed. Further, a drive output coupling (drive output unit: not shown) on the apparatus main body 100 </ b> A side is coupled to the drive input coupling 46. When the driving force is transmitted from the driving output coupling to the driving input coupling 46, the drum 1, the developing roller 42, the toner supply roller 48, and the toner stirring member 61 are respectively set at a predetermined speed according to the image forming operation. It is driven to rotate in the direction of rotation. Further, an output electrical contact (not shown) on the apparatus main body 100A side is electrically connected to an input electrical contact (not shown) on the cartridge 7 side. By applying a predetermined bias from the output electrical contact to the input electrical contact, a predetermined charging bias and developing bias between the charging roller 2 and the developing roller 42 are applied according to the image forming operation. Further, the slit opening 63 as the laser beam incident opening corresponds to the laser emission window 81 (81a, 81b, 81c, 81d) provided with the upper surface plate 80 of the laser scanner unit 3. The laser beam L (La, Lb, Lc, Ld) output from the laser scanner unit 3 enters the cartridge 7 through the lower slit opening 63 and irradiates the lower surface of the drum 1.

<Process cartridge replacement method>
As each cartridge 7 mounted on the apparatus main body 100A is used for image formation, the toner stored in the toner storage chamber 47a of the developing unit 4 is consumed. Therefore, first to fourth developer remaining amount detecting means 25 (25a, 25b, 25c, 25d) for optically detecting the remaining amount of toner in each cartridge 7 are provided. Then, in the control circuit part A, the remaining amount value detected by the developer remaining amount detecting means 25 is compared with a preset threshold value for cartridge life warning or life warning. For a cartridge whose toner has decreased to a remaining amount value that is less than the threshold value, a life warning or a life warning for the cartridge is displayed on the display unit of the operation unit C. As a result, the user is urged to prepare a cartridge for replacement or to replace the cartridge, thereby maintaining the quality of the output image.

  In the image forming apparatus 100 of this embodiment, the replacement of each cartridge 7 is performed by opening the door 21 that is an opening / closing member of the apparatus main body 100A as shown in FIG. An opening 60 that allows the cartridge to pass therethrough is provided in the front frame, which is a skeleton of the apparatus main body 100A, in order to attach and detach the cartridge 7. That is, an opening for inserting the cartridge 7 into the cartridge mounting portion 22 (22a, 22b, 22c, 22d) in the apparatus main body 100A and for taking out the cartridge 7 from the cartridge mounting portion 22 is provided.

  The door 21 is disposed in the apparatus main body 100A so as to be movable between a closed position that covers and closes the opening 60 and an open position that opens the opening 60. When the door 21 is opened, an interlocking mechanism (not shown) that interlocks with the opening operation causes each cartridge 7 in the apparatus main body 100A to move from the positioning state (first state) in which image formation is possible to the apparatus main body 100A. The detachable non-positioning state (second state) is set. The conversion from the first state to the second state is performed by moving the cartridge 7 downwardly. Therefore, the cartridge 7 to be replaced is pulled out toward the front side of the arrow J while being slid along the guide rail of the cartridge mounting portion, and is taken out of the apparatus main body 100A. Then, the new cartridge 7 is inserted into the apparatus main body 100A from the opening 60 with the driving side first, and is engaged with the guide rail of the cartridge mounting portion, and is sufficiently pushed in the direction toward the inner side of the arrow K. After all the cartridges 7 to be replaced are replaced with new ones, the door 21 is closed. By the interlocking mechanism that interlocks with the closing operation of the door 21, each cartridge 7 of each cartridge mounting portion 22 in the apparatus main body 100A can form an image from a non-positioning state (second state) in which the cartridge 7 can be attached to and detached from the apparatus main body 100A. To a proper positioning state (first state). The conversion from the second state to the first state is performed by moving the cartridge 7 upwardly.

<Developer remaining amount detection means>
The light transmission type first to fourth developer remaining amount detecting means 25 for optically detecting the remaining amount of toner (developer remaining amount) accommodated in the developing unit 4 of each cartridge 7 are mainly shown in FIGS. This will be described with reference to FIG.

  FIG. 7 is a perspective view of a portion of the developer remaining amount detecting means 25. FIG. 8 is a cutaway perspective view of a portion of the developer remaining amount detecting means 25. 9A is a top view of the light transmitting member of the detected unit, FIG. 9B is a diagram viewed from (b)-(b) in (a), and FIG. 9C is (c)-( c) A line view.

  The first to fourth developer remaining amount detecting means 25 (25a, 25b, 25c, 25d) are respectively a detection unit 8 (8a, 8b, 8c, 8d) and a detected unit 30 (30a, 30b, 30c). -30d).

  The detection unit 8 includes a light emitting unit (for example, an LED) 27 that emits light and a light receiving unit (for example, a phototransistor) 28 that receives light from the light emitting unit 27 and is held by a holding member 29. The detection unit 8 is attached to the upper surface plate 80 of the laser scanner unit 3 in an upward posture as a unit on the apparatus main body 100A side.

  The detected unit 30 is disposed on the outer wall surface 47d of the toner storage chamber 47a of the cartridge 7 as a unit on the cartridge 7 side. The unit 30 is mounted on the upper side of the detection unit 8 on the apparatus main body 100A side when the cartridge 7 is mounted in a positioning state capable of forming an image with respect to the apparatus main body 100A and the developing roller 42 is in contact with the drum 1. It is located corresponding to the predetermined. As a result, the developer remaining amount detecting means 25 is constituted by the detection unit 8 and the detected unit 30.

  In the detected unit 30, a first and second pair of light transmission members 31, 32 are arranged vertically facing each other along the longitudinal direction of the developing roller 42. The first and second light transmitting members 31 and 32 are attached to the wall surface 47d of the toner storage chamber 47a via the support member 33. The first light transmission member 31 has a transmission window 31a that is a light emitting portion. The second light transmission member 32 has a transmission window 32a which is a light incident part. The two transmission windows 31 a and 32 a protrude into the toner storage chamber 47 a of the developing unit 4.

  In the first light transmission member 31, the transmission window 31a and the light guide 31b are integrated. The light guide 31b is a member that guides the detection light N (N1) emitted upward from the light emitting unit 27 of the detection unit 8 on the apparatus main body 100A side to the inside of the toner storage chamber 47a.

  In the second light transmission member 32, the transmission window 32a and the light guide 32b are integrated. The light guide 32b is a member that guides the detection light N (N2) that has passed through the inside of the toner storage chamber 47a to the upward light receiving portion 28 on the detection unit 8 on the apparatus main body 100A side.

  Further, the light emission surface 31 d of the transmission window 31 a of the first light transmission member 31 faces the light incident surface 32 d of the transmission window 32 a of the second light transmission member 32. The light guide 31b of the first light transmitting member 31 is provided with a reflecting surface 31c so that light incident from the light emitting unit 27 is guided to the light emitting surface 31d. In addition, the light guide 32 b of the second light transmission member 32 is provided with a reflection surface 32 c so that the light N incident from the light incident surface 32 d of the transmission window 32 a is guided to the light receiving unit 28.

  Thus, an optical path is formed from the light emitting portion 27 to the downward surface 31e of the light guide 31b on the first light transmission member 31 side → the light guide 31b → the reflection surface 31c → the light emission surface 31d of the transmission window 31a. Further, from the light emission surface 31d of the transmission window 31a on the first light transmission member 31 side, the light incident surface 32d of the transmission window 32a on the second light transmission member 32 side → the reflection surface 32c → the light guide 32b → the light guide 31b. An optical path from the downward surface 32e to the light receiving unit 28 is formed.

  In FIG. 7, reference numeral 34 denotes a protective cover disposed on the light guides 31 b and 32 b of the first and second light transmitting members 31 and 32. 8 and 9, the protective cover 34 is omitted.

  The toner in the toner storage chamber 47a is lifted along the inner wall surface in the cross section of the toner storage chamber 47a by the toner stirring member 61 being rotated at a predetermined speed in the direction of arrow M according to the image forming operation. While stirring and transporting. A part of the agitated / conveyed toner is sent to the developing chamber 47b from the opening 47c and used for image formation. The toner stored in the toner storage chamber 47a is sequentially sent to the development chamber 47b and decreases as it is used for image formation.

  On the other hand, in the detected unit 30, when the toner is interposed between the transmission windows 31a and 32a protruding into the toner storage chamber 47a, the detection light N emitted from the light emitting unit 27 is blocked, and the light receiving unit 28 The detection light N is not received. Further, when no toner is interposed between the transmission windows 31a and 32a, the detection light N emitted from the light emitting unit 27 is received by the light receiving unit 28 without being blocked. The state where the toner is interposed between the transmission windows 31a and 32a and the state where the toner is not interposed are alternately generated by the toner flow accompanying the rotation of the toner stirring member 61 according to the image forming operation. Then, as the amount of toner in the toner storage chamber 47a decreases, the light shielding time of the detection light N becomes shorter, and conversely, the transmission time of the detection light N becomes longer.

  The control circuit portion A utilizes the fact that the light shielding time and the transmission time detected by the light receiving portion 28 change depending on the amount of toner due to the toner flow accompanying the rotation of the toner stirring member 61 as described above. The remaining toner amount is estimated. Then, the estimated remaining toner amount is compared with a predetermined threshold value, and a life warning or a life warning for the cartridge is displayed on the display unit of the operation unit C.

<< Process cartridge presence detection means >>
Next, a configuration for detecting the presence or absence of the process cartridge 7 (7a, 7b, 7c, 7d) using the optical developer remaining amount detecting means 25 (25a, 25b, 25c, 25d) and the image detecting means 19 is used. This will be described with reference to the flowchart of FIG.

  The presence / absence detection of the cartridge 7 is performed by using the developer remaining amount detection means 25 and the image detection means 19 to determine whether or not the cartridge 7 is attached to the apparatus main body 100A without disposing a dedicated presence / absence detection means. This is what the control circuit unit A uses.

  The control circuit unit A executes a control sequence for CRG presence / absence detection shown in the flowchart of FIG. 10 at a predetermined control timing such as when the power is turned on. Since the image forming apparatus of the present embodiment includes the first to fourth cartridges 7a, 7b, 7c, and 7d, the control sequence for detecting the presence or absence of CRG in FIG. 7d is executed simultaneously or sequentially.

  1) The control circuit unit A detects the remaining amount of toner by the developer remaining amount detecting means 25 for the cartridge 7. When the light receiving unit 28 detects light emitted from the light emitting unit 27 of the developer remaining amount detecting means 25 (Yes in step S1), it is determined that the cartridge 7 is in the apparatus main body 100A (step 6).

  Here, in the step S1, as the state where the light receiving unit 28 does not detect the light emitted from the light emitting unit 27, the following state can be considered. Since a sufficient amount of toner is present in the toner storage chamber 47a of the cartridge 7, even if the toner stirring member 61 rotates, the optical path between the light emitting surface 31d and the light incident surface 32d is shielded by the toner. It is held in a state. Since the cartridge 7 is not mounted, the light emitted from the light emitting unit 27 passes upward and does not enter the light receiving unit 28.

  2) When the light receiving unit 28 does not detect the light emitted from the light emitting unit 27 (No in step S1), the control circuit unit A uses the cartridge to be detected for the presence or absence of CRG to determine on the belt 5 A patch forming operation for forming an image (patch) is executed (step S2). If the image can be detected by the image detection means 19 (Yes in step S3), it is determined that the cartridge 7 is in the apparatus main body 100A (step 6).

  3) When the image cannot be detected by the image detection unit 19 (No in step S3), the control circuit unit A performs the second toner remaining amount detection by the developer remaining amount detection unit 25 (step S4). . When the light receiving unit 28 detects the light emitted from the light emitting unit 27 of the developer remaining amount detecting means 25 (Yes in step S4), it is determined that the cartridge 7 is in the apparatus image forming apparatus 100A (step 6). ).

  4) When the light receiving unit 28 does not detect the light emitted from the light emitting unit 27 in the second toner remaining amount detection (No in step S4), the control circuit unit A detects that the cartridge 7 is the main body of the apparatus. It is determined that it is not mounted in 100A (step 5: no CRT).

  5) The control circuit unit A displays a message to that effect on the display unit of the operation unit C for the cartridge determined to have no CRT, and prohibits the image forming apparatus 100 from executing the image forming operation.

  However, when the cartridge 7 is not in the apparatus main body 100A, the light 40a emitted from the light emitting unit 27 of the detection unit 8 reaches the upper belt 5 as shown in FIG. Further, the light 40a diffuses. The light 40 a that has reached the belt 5 is reflected by the surface of the belt 5. The light 40b reflected by the belt 5 returns to the light receiving unit 28 of the detection unit 8 as shown in FIG. 11B, and the light receiving unit 28 detects the amount of light. Therefore, in such a state, there is a possibility of erroneous detection that the cartridge 7 is not included in the apparatus main body 100A even though it is not included. That is, in step S1 and step S4 in FIG. 10, there is a possibility that erroneous detection that the cartridge 7 is not included in the apparatus main body 100A is detected.

  A method for preventing such erroneous detection in step S1 and step S4 will be described. As shown in FIG. 12, one of the guide rails 9 (9a, 9b, 9c, 9d) on the upper side in this example is a guide rail that is a guide means for guiding the cartridge 7 when it is inserted into and removed from the apparatus main body 100A. The part is located between the detection unit 8 and the belt 5. The guide rail 9 is disposed at a position where a part or all of the optical path 51 of the light beam emitted upward from the light emitting unit 27 of the detection unit 8 is shielded from the belt 5. Reference numeral 92 denotes a light shielding surface (a part that shields light rays) of the guide rail 9 with respect to the belt 5.

  Thereby, even when the cartridge 7 is not contained in the apparatus main body 100A, the light emitted from the light emitting unit 27 of the detection unit 8 does not reflect the surface of the belt 5 and enters the light receiving unit 28. False detection can be prevented.

  As described above, even when the cartridge 7 is not inserted into the apparatus main body 100A without adding parts, it is not erroneously detected that the cartridge 7 is in the apparatus main body 100A. Therefore, it is possible to provide an image forming apparatus provided with a highly accurate and reliable cartridge presence / absence detecting means.

[Example 2]
In this embodiment, as shown in FIG. 13, the shielding surface 92 of the guide rail 9 prevents the shielded light from being reflected and enters the light receiving unit 28 of the detection unit 8. Has an angle α in the horizontal direction. That is, the portion 92 of the guide rail 9 that shields the light beam has an angle α such that the reflected light beam 51 a that reflects the light beam 51 emitted from the light emitting unit 27 does not reach the light receiving unit 28 of the detection unit 8.

  As a result, even when the cartridge 7 is not in the apparatus main body 100A, the light emitted from the light emitting unit 27 of the detection unit 8 does not reflect the surface of the belt 5 and enter the light receiving unit 28. Further, the light emitted from the light emitting unit 27 is not reflected on the shielding surface 92 of the guide rail 9 and enters the light receiving unit 28. For this reason, the erroneous detection can be prevented. Accordingly, it is possible to provide an image forming apparatus provided with a more reliable process cartridge presence / absence detecting means.

[Example 3]
In the present embodiment, in the first or second embodiment, the portion 92 of the guide rail 9 that shields the light beam is subjected to a process for reducing the surface reflectance relative to the other portion of the guide rail 9. Features.

  That is, as shown in FIG. 14, at least the light shielding surface 92 of the guide rail 9 disposed at a position where the light 40 emitted from the light emitting unit 27 of the detection unit 8 is shielded is another part of the guide rail 9. Compared with, surface treatment 93 for reducing the surface reflectance is applied.

  Examples of the treatment 93 for reducing the surface reflection include roughening the surface with sand blasting, black plating, black coating, molding a textured surface, and applying an antireflection sheet.

  In the light shielding surface 92 subjected to such surface treatment 93, the surface reflectance of the sheet metal material or the molded product is reduced by about 1/2 to 1/3 of that before the treatment. Thus, if the amount of reflected light is reduced and the amount of light taken in is lower than the slice level at which the light receiving unit 28 determines the detection of light, the reflected light does not return to the light receiving unit 28 and erroneous detection is prevented.

  Such a means is effective when there is a restriction that the angle of the light shielding surface 92 cannot be set to an angle α that does not reflect the light emitted from the light emitting unit 27 to the light receiving unit 28 as in the second embodiment.

  Therefore, even when the light shielding surface 92 of the guide rail 9 cannot be formed at an angle at which light is not reflected by the light receiving unit 28, the light emitted from the light emitting unit 27 is reflected by the light shielding surface 92 and enters the light receiving unit 28. Can be prevented.

  Further, as in the second embodiment, the light shielding surface 92 of the guide rail 9 is set to an angle α that does not reflect the light emitted from the light emitting unit 27 to the light receiving unit 28. Further, if the surface treatment 93 of the third embodiment is added to this and used, the possibility that the light reflected from the light shielding surface 92 is reflected on the peripheral parts and irradiated to the image forming unit can be reduced. Therefore, it is possible to provide a more reliable image forming apparatus.

  The electrophotographic image forming apparatus has been described above as an example, but the present invention can be applied to an electrostatic recording image forming apparatus and a magnetic recording image forming apparatus to obtain the same effect.

FIG. 2 is a schematic longitudinal front view of the image forming apparatus according to the first exemplary embodiment, illustrating an image forming operation state. FIG. 2 is a partially enlarged view of FIG. 1. 1 is an external perspective view of an image forming apparatus in a state in which a door for opening and closing an apparatus main body is closed. FIG. 2 is an external perspective view of the image forming apparatus showing a state in which the door is opened and the first process cartridge is inserted or pulled out from the apparatus main body. (A) is an external perspective view of the process cartridge viewed from the front side (non-driving side) in the mounting direction, (b) is an external perspective view of the process cartridge viewed from the back side (driving side) in the mounting direction, (c) FIG. 3 is an external perspective view of the process cartridge as viewed from the developing unit side. FIG. 2 is a partially enlarged cross-sectional view of a process cartridge mounted at a position where image formation can be performed in the apparatus main body and its surroundings. FIG. 6 is a perspective view of a portion of developer remaining amount detecting means. FIG. 6 is a cutaway perspective view of a portion of developer remaining amount detecting means. (A) is a top view of the light transmission member of the unit to be detected, (b) is a (b)-(b) line view in (a), and (c) is a (c)-(c) line in (a). FIG. It is an operation | movement flowchart of a process cartridge presence / absence detection control sequence. FIG. 10 is an explanatory diagram in a case where erroneous detection of process cartridge presence / absence detection occurs. It is explanatory drawing of a misdetection prevention structure. It is explanatory drawing of the misdetection prevention structure in Example 2. FIG. It is explanatory drawing of the misdetection prevention structure in Example 3. FIG.

Explanation of symbols

  1. Image bearing member, 5. Intermediate transfer member, 7 (7a, 7b, 7c, 7d), Process cartridge, 8 (8a, 8b, 8c, 8d), Detection unit, 9 (9a, 9b,. 9c · 9d) ··· Process cartridge guide means (guide member), 18 ··· Secondary transfer means, 22 (22a · 22b · 22c · 22d) · · Process cartridge mounting portion, 25 (25a · 25b · 25c · 25d) ..Developer remaining amount detecting means, 27..Light emitting part, 28..Light receiving part, 30 (30a, 30b, 30c, 30d) .. Detected unit, 42..Developing member, 47a..Developer storage part , 51... Light, 70... Image detection means, 92... Light shielding part, 93... Processing section for reducing surface reflectance, 100.

Claims (3)

At least an image carrier on which a latent image is formed; a developing member that develops the latent image formed on the image carrier with a developer; and a developer storage unit that stores the developer. A plurality of process cartridges that can be attached to and detached from the apparatus main body of the image forming apparatus by being guided by guide means disposed in a mounting portion of the apparatus main body;
An intermediate transfer body on which a developed image formed on the image carrier of the process cartridge is primarily transferred;
Secondary transfer means for secondary transfer of the developed image formed on the intermediate transfer member to a recording medium;
A developer remaining amount detecting means which is provided for each of the plurality of process cartridges and optically detects the remaining amount of developer in the developer accommodating portion;
Image detecting means for detecting a developed image formed on the intermediate transfer member;
In the image forming apparatus for detecting the presence or absence of the process cartridge with respect to the apparatus main body using the developer remaining amount detecting means and the image detecting means,
The developer remaining amount detecting means is provided on a detection unit disposed on the apparatus main body side and on the process cartridge side, and the process cartridge is mounted on the apparatus main body. A detected unit located opposite the detection unit,
The detection unit has a light emitting part and a light receiving part in which light rays are directed toward the intermediate transfer body, respectively.
The guide means includes a guide member positioned at least between the detection unit and the intermediate transfer member, and in a state where the process cartridge is not attached to the apparatus main body, a part of the guide member is An image forming apparatus, wherein a part or all of an optical path of a light beam emitted from a light emitting unit is shielded from the intermediate transfer member.   The portion of the guide member that shields the light beam has an angle such that a reflected light beam reflected by the light beam emitted from the light emitting unit does not go to the light receiving unit. The image forming apparatus described.   3. The image forming apparatus according to claim 1, wherein the portion of the guide member that shields the light beam is subjected to a process of reducing surface reflectance relative to other portions of the guide member.