Image forming apparatus

Abstract

This simple configuration enables detection of replacement time and detection of whether or not a new part has been replaced. [Solution] The device comprises a rotating member, a first rotating body to which driving force is input, a second rotating body to which driving force is transmitted from the first rotating body and transmitted to the rotating member, and a biasing member that biases the first rotating body relative to the second rotating body. The first rotating body is movable between a first position and a second position in the direction of the rotation axis, and the state of the detection unit changes according to the axial movement of the first rotating body. The detection pattern of the detection signal output by the detection unit during a predetermined period after the start of driving of the drive source differs depending on whether the first rotating body is in the first position and the rotational load torque of the rotating member is less than a predetermined value, whether the first rotating body is in the second position and the rotational load torque is less than a predetermined value, or whether the first rotating body is in the second position and the rotational load torque is greater than or equal to a predetermined value.

Description

Technical Field

[0001] The present invention relates to an image forming apparatus such as a printer, a copier, a facsimile apparatus, or a multifunction machine having a plurality of functions among these functions, using an electrophotographic method or an electrostatic recording method.

Background Art

[0002] In an image forming apparatus such as a printer using an electrophotographic method, after transferring a toner image from an image carrier to a transfer body, waste toner such as toner remaining on the image carrier is removed from the image carrier by cleaning means and collected in a waste toner collection container. The waste toner collection container may be provided with a full detection means to prevent the waste toner from leaking out. The waste toner collection container is replaced by an operator such as a user or a service person after the full state is detected. Further, when it is detected that the waste toner collection container has been replaced, the full detection state by the full detection means is reset, and the image forming operation can be performed.

[0003] Patent Document 1 discloses a configuration for detecting the rotational load of a stirring member that rotates in a waste toner collection container to stir the waste toner and performing full detection of the waste toner collection container. When the attachment / detachment of the waste toner collection container is detected after the full state of the waste toner collection container is detected, a monitoring number is set and the countdown is started. If the full state is detected again before the monitoring number reaches zero, it is determined that the waste toner collection container has not been replaced, and if the full state is not detected again, it is determined that the waste toner collection container has been replaced. Thereby, when the waste toner collection container is simply attached / detached without being replaced, the full state is detected again before reaching the monitoring number, so that the possibility of false detection regarding the replacement of the waste toner collection container can be reduced.

[0004] Furthermore, Patent Document 2 discloses the following configuration: The transfer unit is equipped with a detection lever that takes on different orientations for the transfer unit included with the main unit of the device and the replacement transfer unit. During the initial operation of the image forming apparatus, it is determined whether the unit has been replaced with a new one based on the detection result of the orientation of the detection lever. This allows the device to continue operating even if the transfer unit reaches the end of its lifespan before the main unit of the device, or if the transfer unit malfunctions, by detecting that the transfer unit has been replaced with a new one. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2009-265281 [Patent Document 2] Japanese Patent Publication No. 2019-66597 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] However, the replacement detection method described in Patent Document 1 requires detection of the removal or attachment of the waste toner collection container after the waste toner collection container has been detected as full. Therefore, if the waste toner collection container is removed or attached before the waste toner collection container is detected as full, it is not possible to correctly detect whether or not the waste toner collection container has been replaced with a new one.

[0007] Furthermore, if the waste toner collection container fullness detection means and the new toner replacement detection means, as described in Patent Document 2, are mounted separately on the main body of the device, it will lead to an increase in the size and cost of the device due to an increase in the number of parts.

[0008] Therefore, the objective of the present invention is to enable detection of the replacement time for a replacement unit and detection of whether or not the replacement unit has been replaced with a new one, using a simple configuration. [Means for solving the problem]

[0009] The above objective is achieved by the image forming apparatus according to the present invention. In summary, the present invention provides an apparatus body having an image forming unit that forms an image with toner, a drive source that generates a driving force, and a detection unit that can take on a first state and a second state and outputs a detection signal corresponding to the first state and the second state, respectively, and a replacement unit that is detachable from the apparatus body, comprising a rotating member, a first rotating body that rotates when a driving force is input from the drive source, a second rotating body provided coaxially with the first rotating body and rotates when a driving force is transmitted by the first rotating body and transmits the driving force toward the rotating member, and the rotation axis direction of the first rotating body The replacement unit includes a biasing member that biases the first rotating body relative to the second rotating body along a certain direction, wherein the first rotating body is movable between a first position and a second position, where the relative position of the first rotating body relative to the second rotating body in the direction of rotation of the first rotating body is different, in conjunction with the change in the relative position of the second rotating body relative to the first rotating body in the direction of rotation of the first rotating body according to the magnitude of the rotational load torque of the rotating member, and the detection unit changes state between the first state and the second state in accordance with the movement of the first rotating body between the first position and the second position, In the new replacement unit, the first rotating body is mounted such that it is in the second position before the rotation of the rotating member begins. The image forming apparatus is characterized in that the detection pattern of the detection signal output by the detection unit during a predetermined period after the drive of the drive source is started while the replacement unit is mounted on the main body of the apparatus differs depending on whether the first rotating body is in the first position and the rotational load torque of the rotating member is less than a predetermined value when the drive of the drive source is started, whether the first rotating body is in the second position and the rotational load torque of the rotating member is less than the predetermined value when the drive of the drive source is started, or whether the first rotating body is in the second position and the rotational load torque of the rotating member is equal to or greater than the predetermined value when the drive of the drive source is started. [Effects of the Invention]

[0010] According to the present invention, it is possible to detect when a replacement unit needs to be replaced and to detect whether or not the replacement unit has been replaced with a new one, using a simple configuration. [Brief explanation of the drawing]

[0011] [Figure 1] This is a cross-sectional view showing the overall configuration of the printer. [Figure 2] This is a cross-sectional view showing a printer with its door open. [Figure 3] This is a cross-sectional view showing a printer with the fuser unit moved. [Figure 4] This is a cross-sectional view showing the printer with the transfer unit and tray unit extended. [Figure 5] This is a cross-sectional view showing a printer with the transfer unit extended independently. [Figure 6] This is a perspective view showing the overall configuration of the transfer unit. [Figure 7] This is a perspective view of the transfer unit to illustrate the waste toner transport path. [Figure 8] This is a perspective view showing the waste toner transport path and drive coupling mechanism. [Figure 9] This is a perspective view of the drive coupling mechanism in Embodiment 1. [Figure 10] This is an exploded perspective view of the drive coupling mechanism in Example 1. [Figure 11] These are perspective and front views of the movable gear and fixed gear in Example 1. [Figure 12] This is a schematic diagram illustrating the operation of the drive coupling mechanism in Example 1. [Figure 13] This is a perspective view illustrating the operation of the detection mechanism in Example 1. [Figure 14] This is a cross-sectional view illustrating the operation of the detection mechanism in Example 1. [Figure 15] This chart shows the detection pattern when near-full is detected in Example 1. [Figure 16] This is a flowchart illustrating the near-full detection process in Example 1. [Figure 17] This is a schematic diagram illustrating the operation of the drive coupling mechanism when a new part replacement is detected in Example 1. [Figure 18] It is a flowchart diagram of new product replacement detection in Example 1. [Figure 19] It is a chart diagram showing the detection pattern at the time of new product replacement detection in Example 1. [Figure 20] It is a perspective view and a front view showing the movable gear and the fixed gear in Example 2. [Figure 21] It is a schematic diagram for explaining the operation of the drive coupling mechanism at the time of near-full detection in Example 2. [Figure 22] It is a cross-sectional view for explaining the operation of the detection mechanism in Example 2. [Figure 23] It is a chart diagram showing the detection pattern at the time of near-full detection in Example 2. [Figure 24] It is a flowchart diagram of near-full detection in Example 2. [Figure 25] It is a schematic diagram for explaining the operation of the drive coupling mechanism at the time of new product replacement detection in Example 2. [Figure 26] It is a chart diagram showing the detection pattern at the time of new product replacement detection in Example 2. [Figure 27] It is a flowchart diagram of new product replacement detection in Example 2. [Figure 28] It is a block diagram showing the schematic control configuration of the printer.

Embodiments for Carrying Out the Invention

[0012] Hereinafter, the image forming apparatus according to the present invention will be described in more detail with reference to the drawings.

[0013] [Example 1] <Overall Configuration of the Image Forming Apparatus> The overall configuration of the image forming apparatus in this embodiment will be explained using Figure 1. Figure 1 is a cross-sectional view showing the overall configuration of the image forming apparatus in this embodiment. In this embodiment, the image forming apparatus is a tandem-type color laser beam printer (hereinafter simply referred to as "printer") 1 that employs an intermediate transfer method and is capable of forming a full-color image on a sheet S using an electrophotographic method.

[0014] Regarding printer 1 and its elements, the right side in Figure 1 is referred to as the "front" side, and the left side in Figure 1 is referred to as the "rear" side. Also, regarding printer 1 and its elements, the left side (the front of the paper in Figure 1) when viewed from the front of printer 1 is referred to as the "left" side, and the right side (the back of the paper in Figure 1) is referred to as the "right" side. The left-right direction connecting the left and right sides is assumed to be approximately parallel to the rotation axis direction of the photosensitive drum 61, which will be described later, and the rotation axis direction of the tension roller of the intermediate transfer belt 41, which will be described later. Furthermore, in this embodiment, printer 1 is positioned so that the front-back direction and the left-right direction are approximately parallel to the horizontal direction H, and is used for image formation. Also, regarding printer 1 and its elements, up and down refers to up and down in the direction of gravity (vertical direction) V, but does not mean only directly above and directly below, but also includes the sides above and below the horizontal plane passing through the position or element of interest. Furthermore, while sheet S is typically made of paper, and therefore sometimes referred to simply as paper, sheet S is not limited to paper. It can also be made of materials other than paper, such as plastic sheets, or materials containing materials other than paper.

[0015] The printer 1 comprises a main body (housing) 1a, a scanner 2 which is an exposure device as an exposure means, a control unit (control circuit) 3 as a control means, and a door 20 which is an opening / closing member that can be opened and closed relative to the main body 1a. The printer 1 also comprises a sheet feeding unit 30, a transfer unit 40 which is a transfer device (intermediate transfer device) as a transfer means, a tray unit 50 as a moving unit (support unit), and a fixing device 80 as a fixing means. The part including the main body 1a and the door 20 can also be called the main frame 1i. The main frame 1i includes the exterior of the printer 1.

[0016] The main unit 1a houses a scanner 2, a control unit 3, a sheet feeding unit 30, a transfer unit 40, a tray unit 50, and a fixing device 80.

[0017] The sheet feeding unit 30 includes a loading tray 31 for loading sheets S, which are sheet-shaped recording materials (transfer materials, recording media, paper), and a feeding roller 32 as a feeding member. The loading tray 31 can be pulled out from the main body 1a toward the door 20 (front side). Sheets S can then be replenished in the loading tray 31 that has been pulled out from the main body 1a.

[0018] The tray unit 50 includes a tray 51 as a support member (drawer) and four cartridges (image forming units) PY, PM, PC, and PK. The tray 51 has a tray handle 52. Each cartridge PY, PM, PC, and PK is removably mounted on the tray 51.

[0019] In this embodiment, each cartridge PY, PM, PC, and PK is independently removable from the tray 51. The four cartridges PY, PM, PC, and PK each form images (toner images) of yellow (Y), magenta (M), cyan (C), and black (K), respectively. The four cartridges PY, PM, PC, and PK each contain toner as a developer for yellow (Y), magenta (M), cyan (C), and black (K), respectively. In this embodiment, a one-component developer is used as the developer. Each cartridge PY, PM, PC, and PK has substantially the same configuration except for the color of the toner it contains. Elements with the same or corresponding functions or configurations provided for each of the yellow, magenta, cyan, and black colors may be described collectively by omitting the Y, M, C, and K at the end of the symbols indicating that they are elements for one of the colors. The tray unit 50 can be said to have a plurality of cartridges P and a tray 51 on which the plurality of cartridges P are removablely mounted.

[0020] In this embodiment, the tray unit 50 has a plurality of photosensitive drums 61 (61Y, 61M, 61C, 61K), a plurality of charging rollers 62 (62Y, 62M, 62C, 62K), and a plurality of developing rollers 71 (71Y, 71M, 71C, 71K). Specifically, the tray unit 50 has four photosensitive drums 61, four charging rollers 62, and four developing rollers 71. The photosensitive drum 61 is a rotatable drum-type (cylindrical) photoreceptor (electrophotographic photoreceptor) as a first image carrier. The charging rollers 62 are roller-type charging members as charging means. The developing rollers 71 are developer carriers (developing members) that carry toner in the toner storage section provided in the tray 51 or cartridge P and transport it toward the photosensitive drum 62. The rotation axis direction of the photosensitive drum 61, the rotation axis direction of the developing roller 71, and the rotation axis direction of the charging roller 62 are approximately parallel.

[0021] The parts that form the image for each color (including the photosensitive drum 61, charging roller 62, and developing roller 71) can also be called stations. The black cartridge PK is installed in the black station. The cyan cartridge PC is installed in the cyan station. The magenta cartridge PM is installed in the magenta station. The yellow cartridge PY is installed in the yellow station.

[0022] The photosensitive drum 61, the charging roller 62, and the developing roller 71 may be provided in either the cartridge P or the tray 51. In this embodiment, the cartridge P includes the photosensitive drum 61, the charging roller 62, and the developing roller 71. The tray unit 50 may also have a drum cleaning unit (drum cleaning device) as a photoreceptor cleaning means for removing toner from each photosensitive drum 61. In other words, the tray unit 50 may have multiple drum cleaning units that clean the surface of each photosensitive drum 16. The drum cleaning unit can be provided in either the cartridge P or the tray 51. For example, the drum cleaning unit uses a cleaning blade, which acts as a cleaning member that contacts the surface of the photosensitive drum 61, to scrape toner from the surface of the rotating photosensitive drum 61 and collect it in a recovered toner storage unit provided in the tray 51 or cartridge P.

[0023] The transfer unit 40 includes an intermediate transfer belt (hereinafter also simply referred to as "belt") 41, primary transfer rollers 42 (42Y, 42M, 42C, 42K), a cleaning unit 43, a drive roller 46, and tension rollers (driven rollers) 47. The belt 41 is an intermediate transfer body composed of an endless belt, serving as a second image carrier. The primary transfer rollers 42 are roller-type primary transfer members serving as primary transfer means. The cleaning unit (belt cleaning device) 43 is a cleaning means for cleaning the surface of the belt 41. The drive rollers 46 and tension rollers 47 are tension rollers that tension the belt 41. The drive rollers 46 drive the belt 41. The tension rollers 47 apply a predetermined tension to the belt 41. The drive roller 46 and tension roller 47 form a primary transfer surface 41a on the belt 41, which is the surface onto which the toner image is transferred from the photosensitive drums 61Y, 61M, 61C, and 61K.

[0024] In this embodiment, the printer 1 has an optical sensor 44 that detects the toner image transferred to the belt 41. In this embodiment, the belt 41 is positioned below each of the photosensitive drums 61Y, 61M, 61C, and 61K. The belt 41 is able to contact the photosensitive drum 61 so that a primary transfer portion is formed between the belt 41 and the photosensitive drum 61. The printer 1 also has a secondary transfer roller 45 positioned opposite the drive roller 46 via the belt 41. The secondary transfer roller 45 is a roller-type secondary transfer member that serves as a secondary transfer means. The secondary transfer roller 45 contacts the belt 41 so that a secondary transfer portion is formed between the belt 41 and the secondary transfer roller 45. The rotational axis direction of the primary transfer roller 42, the rotational axis direction of the drive roller 46, the rotational axis direction of the tension roller 47, and the rotational axis direction of the secondary transfer roller 45 are substantially parallel. In the conveying direction of the sheet S, a pair of registration rollers 4 are positioned in front of the secondary transfer portion as synchronous conveying members.

[0025] The fixing device 80 includes a fixing unit 81 and a flapper 5. The fixing device 80 is in the use position when the image forming operation is performed to form an image on the sheet S. The fixing device 80 is housed inside the main body 1a when it is in the use position. The fixing device 80 is also configured to heat the sheet S when it is in the use position. In this embodiment, the fixing unit 81 includes a heating unit (heating roller) including a heater and a pressurizing unit (pressure roller) that grips and conveys the sheet S together with the heating unit.

[0026] The movement of the transfer unit 40 and the tray unit 50 will be explained using Figures 1, 2, 3, 4, and 5. Figure 2 is a cross-sectional view showing the printer 1 with the door 20 open. Figure 3 is a cross-sectional view showing the printer 1 with the fuser 80 moved. Figure 4 is a cross-sectional view showing the printer 1 with the transfer unit 40 and the tray unit 50 pulled out from the main body 1a. Figure 5 is a cross-sectional view showing the printer 1 with the transfer unit 40 pulled out from the main body 1a by itself.

[0027] The transfer unit 40 and the tray unit 50 are movable from the inside to the outside of the device body 1a. In the horizontal direction H (front-to-back direction), the device body 1a has a first end 1b1 with a body opening 1a1, which is an opening, and a second end 1b2 on the opposite side of the first end 1b1. The tray unit 50 is movable through the body opening 1a1 to a first inner position inside the device body 1a and to a first outer position outside the device body 1a. The transfer unit 40 is movable through the body opening 1a1 to a second inner position inside the device body 1a and to a second outer position outside the device body 1a. The body opening 1a1 may be configured to have an opening through which the tray unit 50 passes and an opening through which the transfer unit 40 passes. When the transfer unit 40 moves from the second inner position to the second outer position, at least the belt 41 moves, and at least a part of the belt 41 protrudes from the device body 1a toward the outside of the device body 1a.

[0028] The direction in which the tray unit 50 moves from the first inner position to the first outer position is called the tray removal direction Dd1, and the direction opposite to the tray removal direction Dd1 is called the tray mounting direction Da1. The tray removal direction Dd1 can be described as the direction from the second end 1b2 to the first end 1b1. The direction in which the transfer unit 40 moves from the second inner position to the second outer position is called the transfer removal direction Dd2, and the direction opposite to the transfer removal direction Dd2 is called the transfer mounting direction Da2. In the transfer removal direction Dd2, the drive roller 46 is located downstream of the tension roller 47. The transfer removal direction Dd2 can be described as the direction from the second end 1b2 to the first end 1b1. The tray removal direction Dd1 and the tray mounting direction Da1 are directions that intersect (preferably approximately perpendicular) with the rotation axis direction of the photosensitive drum 61. The transfer removal direction Dd2 and the transfer mounting direction Da2 are directions that intersect (preferably approximately perpendicular) with the rotation axis direction of the drive roller 46. The rotation axis direction of the drive roller 46 is approximately parallel to the rotation axis direction of the photosensitive drum 61. In the horizontal direction H (front-to-back direction), the fixing device 80 is positioned on one end of the device body 1a (the side on which the first end 1b1 is located).

[0029] The door 20 attached to the main body 1a of the device is movable between a closed position and an open position. As shown in Figure 1, when the door 20 is in the closed position (closed state), the door 20 covers the opening 1a1 of the main body. As shown in Figure 2, when the door 20 is in the open position (open state), the opening 1a1 of the main body is exposed.

[0030] As shown in Figure 1, when the door 20 is in the closed position, the door 20 covers the fuser unit 80 attached to the main body 1a of the device. More specifically, when the door 20 is in the closed position, the upper cover portion 20b of the door 20 is located above the fuser unit 80. The upper cover portion 20b of the door 20 functions as part of the exterior of the printer 1.

[0031] The door 20 can move between an open position and a closed position while the fixing device 80 is supported by the device body 1a. In other words, the door 20 moves from the closed position to the open position so as to move away from the fixing device 80 supported by the device body 1a. Therefore, as shown in Figure 2, when the door 20 is in the open position, the door 20 is away from the fixing device 80 supported by the device body 1a.

[0032] As will be described later, the fixing device 80 is movable from the state shown in Figure 2 to the state shown in Figure 3 so that the main body opening 1a1 is widely exposed. With the door 20 and the fixing device 80 moved as shown in Figure 3, the transfer unit 40 and the tray unit 50 can move from the inside to the outside of the device body 1a through the main body opening 1a1, and after the movement, it will be in the state shown in Figure 4.

[0033] As shown in Figure 4, with the tray unit 50 moved outside the main body 1a of the device, it is permissible to remove each cartridge PY, PM, PC, and PK from the tray 51 and to attach each cartridge PY, PM, PC, and PK to the tray 51. This allows each cartridge PY, PM, PC, and PK to be replaced with a new cartridge PY, PM, PC, and PK, respectively. In this embodiment, cartridge P is detachable from the tray 51 in a direction that intersects (preferably approximately perpendicular to) the rotation axis of the photosensitive drum 61.

[0034] Each cartridge PY, PM, PC, and PK is removed from the tray 51 by moving it away from the transfer unit 40 relative to the tray 51. In other words, each cartridge PY, PM, PC, and PK is removed from the tray 51 by moving it away from the transfer unit 40 relative to the tray 51. In this embodiment, the transfer unit 40 is located below the tray unit 50. Therefore, each cartridge PY, PM, PC, and PK is removed from the tray 51 by moving it upward relative to the tray 51.

[0035] Furthermore, as shown in Figure 5, the transfer unit 40 can be removed from the main body 1a of the apparatus independently of the tray unit 50. This allows the transfer unit 40 to be replaced with a new one.

[0036] <Image Formation Process> The image formation operation of printer 1 will be explained using Figure 1. The control unit 3 of printer 1 starts an image formation operation to form an image on sheet S based on image information (image signal) received from an external host device 400. The external host device 400 is, for example, a personal computer, an image reader, or a facsimile machine.

[0037] When the image forming operation is performed, the fixing device 80 is in the operating position, the tray unit 50 is in the first inner position, the transfer unit 40 is in the second inner position, and the door 20 is in the closed position. With the transfer unit 40 in the second inner position, the belt 41 can contact each of the photosensitive drums 61Y, 61M, 61C, and 61K. At this time, the tray unit 50 is positioned above the transfer unit 40.

[0038] When the image forming operation starts, the photosensitive drum 61 is driven to rotate, and a charging voltage is applied to the charging roller 62. The photosensitive drum 61 is driven to rotate in a clockwise direction in Figure 1. The belt 41 is also driven to rotate. The belt 41 rotates (circumnavigates) in a counterclockwise direction in Figure 1 as the drive roller 46 is driven by the drive motor 5 (Figure 28), which acts as the drive source. The surface of the photosensitive drum 61 is uniformly charged to a predetermined potential with a predetermined polarity (negative polarity in this embodiment) by the charging roller 62. A laser corresponding to the image information is irradiated from the scanner 2 onto the charged surface of the photosensitive drum 61, and the surface of the photosensitive drum 61 is exposed. As a result, an electrostatic latent image (electrostatic image) corresponding to the image information is formed on the surface of the photosensitive drum 61.

[0039] In this embodiment, the developing roller 71 carries the toner in the toner storage section provided in the cartridge P. A developing voltage is applied to the developing roller 71, and toner is supplied from the developing roller 71 to the surface of the photosensitive drum 61 in accordance with the electrostatic latent image formed on the surface of the photosensitive drum 61. As a result, the surface of the photosensitive drum 61 is developed (visualized), and a toner image (toner image, developer image) is formed on the surface of the photosensitive drum 61. In this embodiment, toner charged with the same polarity as the charging polarity of the photosensitive drum 61 (negative polarity in this embodiment) adheres to the exposed area on the photosensitive drum 61, where the absolute value of the charge has decreased after being uniformly charged and then exposed. In this embodiment, the normal charging polarity of toner, which is the main charging polarity of toner during development, is negative polarity. In this embodiment, the developing roller 71 develops the electrostatic latent image while in contact with the photosensitive drum 61. However, the printer 1 may be configured such that the developing roller 71 develops the electrostatic latent image with a gap between the developing roller 71 and the photosensitive drum 61.

[0040] For example, when forming a full-color image, toner images of yellow, magenta, cyan, and black are formed on the photosensitive drums 61Y, 61M, 61C, and 61K, respectively.

[0041] In this embodiment, with the tray unit 50 in the first inner position, the developing roller 71 is movable between a contact position in contact with the photosensitive drum 61 and a separated position away from the photosensitive drum 61. Specifically, a switching device (not shown) provided on the main body 1a of the apparatus switches between the developing roller 71 being in the contact position and the developing roller 71 being in the separated position. This allows the developing roller 71 to be kept away from the photosensitive drum 61 when no image forming operation is being performed.

[0042] Furthermore, printer 1 can perform monochrome printing when the developing roller 71 and photosensitive drum 61 of cartridge PK are in contact, and the developing rollers 71 and photosensitive drums 61 of cartridges PY, PM, and PC are separated. Also, printer 1 can perform full-color printing when the photosensitive drums 61 and belt 41 of cartridges PY, PM, PC, and PK are in contact.

[0043] The toner image formed on the photosensitive drum 61 is transferred (primary transfer) to the rotating transfer surface, the belt 41, in the primary transfer section by the action of the primary transfer roller 42. During primary transfer, a primary transfer voltage with the opposite polarity to the normal charging polarity of the toner is applied to the primary transfer roller 42. The toner image transferred onto the belt 41 is transported by the rotation of the belt 41 toward the secondary transfer section, which is formed by the belt 41 and the secondary transfer roller 45. For example, when forming a full-color image, the toner images of yellow, magenta, cyan, and black formed on the photosensitive drums 61Y, 61M, 61C, and 61K are sequentially transferred so that they are superimposed on the same image forming area on the belt 41.

[0044] On the other hand, the main body 1a of the device has a transport path (first path, first transport path) 1c through which the sheet S heading toward the fuser 80 passes. The door 20 also has a double-sided transport path (second path, second transport path) 20a through which the sheet S that has passed through the fuser 80 passes. When the door 20 is closed, it covers the transport path 1c. As shown in Figure 2, when the door 20 is opened, the transport path 1c and the double-sided transport path 20a are exposed. In the sheet feeding section 30, one sheet S is separated from the sheets S loaded on the loading tray 31 at a predetermined timing by the feeding roller 32 and fed. This sheet S is transported through the transport path 1c toward the secondary transfer section and the fuser 80. In other words, the sheet S sent out from the loading tray 31 by the feeding roller 32 is transported to the registration roller pair 4. This sheet S is then transported to the secondary transfer section by the registration roller pair 4 in time with the toner image on the belt 41.

[0045] The toner image formed on the belt 41 is transferred (secondary transfer) in the secondary transfer section to the sheet S, which is being transported between the belt 41 and the secondary transfer roller 45, by the action of the secondary transfer roller 45. During secondary transfer, a secondary transfer voltage with the opposite polarity to the normal charging polarity of the toner is applied to the secondary transfer roller 45. Toner that remains on the belt 41 without being transferred to the sheet S (residual toner) is removed from the belt 41 and collected by the cleaning section 43. The cleaning section 43 has a cleaning blade 43a as a cleaning member that contacts the surface of the belt 41, and a cleaning container 43b that forms a toner collection section. The cleaning blade 43a is located inside the cleaning container 43b. The cleaning section 43 scrapes the toner from the surface of the rotating belt 41 with the cleaning blade 43a and collects it in the cleaning container 43b. The toner removed from the surface of the belt 41 by the cleaning unit 43 is transported from the cleaning unit 43 to the waste toner collection container 10 (Figure 7), which will be described later, and collected (stored) as waste toner.

[0046] The sheet S onto which the toner image has been transferred in the secondary transfer section is transported toward the fuser unit 80. The fuser unit 81 of the fuser unit 80 heats and pressurizes the sheet S carrying the unfixed toner image to fix (melt and solidify) the toner image onto the sheet S. The sheet S with the fixed toner image is then transported toward the flapper 5, which acts as a path switching section.

[0047] The flapper 5 is movable to an discharge position that guides the sheet S, which has passed through the fuser 80, toward the discharge path 1d, and to a reversal position that guides it toward the reversal path 1e. When single-sided printing is performed, in which an image is formed on one side of the sheet S, the sheet S is guided by the flapper 5 to the discharge path 1d and discharged (output) to the discharge tray 1f formed on the top of the device body 1a. On the other hand, when double-sided printing is performed, in which an image is printed on the first side (front side) and the second side (back side) of the sheet S, the sheet S, with the toner image fixed to the first side, is guided by the flapper 5 to the reversal path 1e. After being guided to the reversal path 1e, the direction of transport of this sheet S is reversed. Then, this sheet S is transported toward the secondary transfer section through the double-sided transport path 20a formed in the door 20, and the toner image is transferred to the second side. After that, this sheet S passes through the fuser 80, is guided by the flapper 5 to the discharge path 1d, and discharged to the discharge tray 1f of the device body 1a.

[0048] In this embodiment, the image forming unit 1h is configured to form a toner image on the sheet S by the image forming unit P, the transfer unit 40, the secondary transfer roller 45, etc. In this embodiment, the belt cleaning unit 43 is an example of a cleaning unit that collects toner in the image forming unit 1h. In this embodiment, the waste toner collection container 10 (Figure 7), which will be described later, which contains the toner collected from the belt 41, is an example of a waste toner collection container that contains the toner collected by the cleaning unit (waste toner collected in the main body of the device).

[0049] <Control Configuration> Figure 28 is a block diagram showing the schematic control configuration of printer 1. Printer 1 has a control unit 3 as a control means for comprehensively controlling printer 1. The control unit 3 is composed of a CPU 3a as an arithmetic processing means (arithmetic processing unit), a memory 3b as a storage means (storage unit), and an input / output circuit (not shown) as an input / output means (input / output unit). Memory 3b is composed of ROM, RAM, and EEPROM. Control programs and application programs executed by the CPU 3a are stored in the ROM. RAM functions as a work area for executing the processing of control programs. EEPROM holds data such as various settings that are desired to be retained even when the power to printer 1 is turned off. The CPU 3a controls printer 1 according to the program stored in memory 3b (ROM).

[0050] The control unit 3 is connected to, for example, a detection mechanism 100 (described later), an operation unit 4, a drive motor 5, a scanner 2, and a high-voltage power supply 6. As described later, the detection mechanism 100 can detect the movement of the movable gear 121 in the rotation axis direction of the drive transmission mechanism 120 for driving the waste toner transport screw 113 provided in the waste toner collection container 10. The detection mechanism 100 can then detect when the rotational load torque of the waste toner transport screw 113 exceeds a predetermined value (overload condition). The detection mechanism 100 inputs a signal indicating the detection result to the control unit 3. The operation unit 4 is configured to have a display unit that displays information to the user (operator) under control by the control unit 3, and an input unit that inputs various settings and other information to the control unit 3 based on user operations. The operation unit 3 may be configured to have a touch panel or the like that has the functions of both a display unit and an input unit. In this case, the operation unit 4 displays information on the screen to the user and accepts touch input from the user. The drive motor 5 is a drive source that generates the driving force to rotate the belt 41 (drive roller 46). The printer 1 may also be provided with other drive motors to act as drive sources for other driven parts such as the photosensitive drum 61 and the fuser 80. Furthermore, the drive source for the drive roller 46 as a driven part may be shared with at least a portion of the drive sources for other driven parts such as the photosensitive drum 61 and the fuser 80. The high-voltage power supply 6 applies a predetermined voltage to the charging roller 62, developing roller 71, primary transfer roller 42, secondary transfer roller 45, etc. A separate high-voltage power supply 6 may be provided for each of the above-mentioned application targets, or a high-voltage power supply 6 may be shared for multiple of the above-mentioned application targets. An external host device 400 is connected to the control unit 3. The control unit 3 can control each part of the printer 1 to perform image forming operations based on print instructions and image information input from the external host device 400. Furthermore, as will be described later, the control unit 3 can perform processing to detect and notify the near-full and full states of the waste toner collection container 10, and processing to detect when the waste toner collection container 10 (transfer unit 40) needs to be replaced with a new one.

[0051] <Waste toner transport route> The waste toner transport path will be explained using Figures 6, 7, and 8. Figure 6 is a perspective view showing the overall configuration of the transfer unit 40 in this embodiment. Figure 7 is a perspective view of the transfer unit 40 to explain the waste toner transport path in this embodiment, showing the transfer unit 40 with the belt 41 and the cleaning container 43b of the cleaning unit 43 removed. Figure 8 is a perspective view showing the waste toner transport path and drive coupling mechanism in this embodiment.

[0052] The cleaning unit 43 includes a cleaning container 43b and a cleaning blade 43a provided inside the cleaning container 43b. The cleaning blade 43a extends along the width direction (left-right direction), which is substantially perpendicular to the direction of movement of the surface of the belt 41. The cleaning blade 43a is positioned to contact the drive roller 46 via the belt 41. The cleaning blade 43a is also positioned to contact the surface (outer circumferential surface) of the belt 41 in a counter-direction opposite to the direction of movement of the belt 41. In other words, the cleaning blade 43a is positioned so that its free end in the short direction, which is substantially perpendicular to the longitudinal direction along the width direction of the belt 41, faces upstream of the direction of movement of the surface of the belt 41, and is in contact with the surface of the belt 41. The cleaning blade 43a scrapes toner from the surface of the rotating belt 41 and collects it as waste toner inside the cleaning container 43b. Here, the cleaning blade 43a is in contact with the belt 41 at a predetermined angle, and the toner can be removed from the surface of the belt 41 as the belt 41 moves in one direction. In this embodiment, no driving force is input from the drive source to the drive roller 46 so that the belt 41 and the drive roller 46 rotate in opposite directions.

[0053] The transfer unit 40 has a transfer frame 48 as a frame that supports the drive roller 46, tension roller 47, and each primary transfer roller 42. In this embodiment, a space (region) capable of accommodating waste toner is provided inside the transfer frame 48. In other words, in this embodiment, the transfer frame 48 also serves as the waste toner collection container 10. However, the waste toner collection container 10 may be configured separately from the transfer frame 48 and attached to the transfer frame 48. That is, in this embodiment, the waste toner collection container 10 is provided within the region formed by the inner circumferential surface of the belt 41. In this embodiment, within the device body 1a, the waste toner collection container 10 is positioned so that its bottom surface intersects with the direction of gravity. Also, in this embodiment, the waste toner collection container 10 is configured to be substantially rectangular in shape when viewed in a direction substantially perpendicular to the primary transfer surface 41a of the belt 41. On the upper surface of the waste toner collection container 10, grooves 10bY, 10bM, 10bC, and 10bK are formed along the rotation axis direction (left-right direction) of each primary transfer roller 42, in the portion facing the primary transfer rollers 42Y, 42M, 42C, and 42K. This prevents the waste toner collection container 10 from restricting the rotation of each primary transfer roller 42. The drive roller 46, tension roller 47, and each primary transfer roller 42 are rotatably supported via support parts provided on the transfer frame 48.

[0054] The cleaning unit 43 has a cleaning screw 111 and an intermediate screw 112 inside it, which serve as waste toner transport members for transporting the waste toner removed from the belt 41 by the cleaning blade 43a. The cleaning screw 111 has a rotating shaft arranged along the width direction (left-right direction) of the belt 41 and a helical transport section formed along the axial direction of this rotating shaft. The cleaning screw 111 is driven and connected to a drive roller 46 by a drive coupling (not shown), and rotates by receiving a driving force input from the drive motor 5 to the drive roller 46 via this drive coupling. As the cleaning screw 111 rotates, it transports the waste toner in the direction of arrow Ta in Figure 8 (from right to left). The intermediate screw 112 has a rotating shaft arranged along a direction intersecting the rotation axis direction of the cleaning screw 111 (a direction intersecting the horizontal direction) and a helical transport section formed along the axial direction of this rotating shaft. One end (upper end) of the intermediate screw 112 in the direction of its rotational axis is positioned close to one end (left end) of the cleaning screw 111 in the direction of its rotational axis. The intermediate screw 112 is driven and connected to the cleaning screw 111 at this end and rotates by receiving driving force from the cleaning screw 111. As the intermediate screw 112 rotates, it transports waste toner in the direction of arrow Tb in Figure 8 (from top to bottom). The other end of the intermediate screw 112 in the direction of its rotational axis is positioned close to one end (left and front end) of the waste toner transport screw 113, which will be described later, in the direction of its rotational axis. The intermediate screw 112 is located inside the transport path 43b1 (Figure 6) provided at the left end of the cleaning container 43b. This transport path 43b1 is connected to the inlet 10a (Figure 8) of the waste toner collection container 10, and the inside of the waste toner collection container 10 and the inside of the transport path 43b1 are in communication through this inlet 10a. The waste toner conveyed by the cleaning screw 111 in the direction of arrow Ta in Figure 8 is conveyed by the intermediate screw 112 in the direction of arrow Tb in Figure 8 and flows into the inside of the waste toner collection container 10 from the inlet 10a.

[0055] Furthermore, a waste toner transport screw 113 is provided inside the waste toner collection container 10 as a waste toner transport member. The waste toner transport screw 113 has a rotating shaft and a helical transport section formed along the axial direction of this rotating shaft. One end of the waste toner transport screw 113 in the direction of the rotation axis (the left and front end) is positioned close to the inlet 10a of the waste toner collection container 10. The other end of the waste toner transport screw 113 in the direction of the rotation axis is rotatably supported by a bearing section 10c provided inside the waste toner collection container 10. The waste toner transport screw 113 is driven and connected to a drive roller 46 by a drive coupling mechanism 120, which will be described later, and rotates by receiving driving force input from the drive motor 5 to the drive roller 46 via this drive coupling mechanism 120. As the waste toner transport screw 113 rotates, it transports the waste toner that has flowed into the waste toner collection container 10 from the inlet 10a in the direction of arrow Tc in Figure 8.

[0056] The rotation axis direction of the waste toner transport screw 113 is, when viewed in a direction approximately perpendicular to the primary transfer surface 41a of the belt 12, not perpendicular to the direction of movement of the primary transfer surface 41a (front-to-back direction) or the width direction of the belt 41 (left-to-right direction), but intersects with these directions. The waste toner that flows into the waste toner collection container 10 from the inlet 10a is transported by the waste toner transport screw 113 toward the approximate center of the waste toner collection container 10 when viewed in a direction approximately perpendicular to the primary transfer surface 41a of the belt 41, as shown by the arrow Tc in Figure 8. The end of the spiral transport section of the waste toner transport screw 113 opposite the inlet 10a in the rotation axis direction is located approximately in the center of the waste toner collection container 10. Therefore, the waste toner transported by the waste toner transport screw 113 fills the waste toner collection container 10 while diffusing concentrically from the approximate center of the waste toner collection container 10.

[0057] In this way, the toner removed from the belt 41 by the cleaning blade 43a is transported to the waste toner collection container 10 by the cleaning screw 111 and intermediate screw 112 located inside the cleaning container 43b. The waste toner collection container 10 is also equipped with a waste toner transport screw 113 that transports the waste toner toward the approximate center of the waste toner collection container 10, and the waste toner is accumulated inside the waste toner collection container 10. The waste toner transport screw 113, as a driven member, rotates when driving force is input from the drive motor 5, which is the driving source, via the drive coupling mechanism 120 described later. When the number of sheets of paper fed by the printer 1 increases and the amount of waste toner increases, the waste toner is transported radially from the center outwards in the waste toner collection container 10.

[0058] In this embodiment, when the amount of waste toner accumulated in the waste toner collection container 10 exceeds a predetermined amount (typically exceeding the predetermined amount), this condition is detected and a warning is issued to the user. In this embodiment, this condition is referred to as the "near-full state," and the warning issued to the user when this condition occurs is referred to as the "near-full notification." In this embodiment, even after the near-full notification is issued, the printer 1 can continue printing until the amount of waste toner collected in the waste toner collection container 10 reaches a predetermined amount (second predetermined amount). When the amount of waste toner collected in the waste toner collection container 10 reaches a predetermined amount (second predetermined amount) that can be stored in the waste toner collection container 10, this condition is detected and a warning is issued to the user. In this embodiment, this condition is referred to as the "full state," and the warning issued to the user when this condition occurs is referred to as the "full notification." In this embodiment, when the full notification is issued, the printer 1 stops operating (printing is prohibited).

[0059] As the amount of waste toner in the waste toner collection container 10 increases, the density of the waste toner increases. As a result, the resistance generated when the waste toner is transported by the waste toner transport screw 113 increases, and the rotational load torque of the waste toner transport screw 113 increases.

[0060] In this embodiment, when the rotational load torque of the waste toner transport screw 113 exceeds a predetermined value (overload condition) (typically exceeding the predetermined value), the detection mechanism 100 (Figure 13, etc.), described later, detects that the waste toner collection container 10 is nearly full. Based on the detection result from the detection mechanism 100, the control unit 3 notifies the user of a warning, such as by displaying a message on the screen of the operation unit 4 provided on the printer 1. This warning can be given by displaying a message prompting the user to prepare to replace the waste toner collection container 10. Alternatively, or in addition to the operation unit 4, a similar warning can be displayed on the display unit of an external host device 400 connected to the printer 1.

[0061] Furthermore, in this embodiment, even after detecting that the waste toner collection container 10 is nearly full, the printer 1 can continue printing until the amount of waste toner collected in the waste toner collection container 10 reaches a predetermined amount and fills it. In this embodiment, the control unit 3 calculates the amount of toner consumed by the printing operation based on image information from the nearly full state to the full state. In other words, the control unit 3 can calculate the amount of toner consumed by the printing operation by counting the number of pixels in the printed image. When the amount of toner consumed by the printing operation since the near full state was detected reaches a predetermined amount, the control unit 3 notifies the user of the warning by displaying it on the screen of the operation unit 4 provided on the printer 1. This warning can be given by displaying a message prompting the user to replace the waste toner collection container 10. However, the means for detecting the amount of waste toner collected in the waste toner collection container 10 after the near full state is detected is not limited to the method described above. For example, methods such as counting the number of sheets of paper fed, providing a detection means to detect when the printer is full, or counting the rotation time or number of rotations of the drive roller 46 (transfer unit 40) may be used. In addition, similar warnings can be displayed on the display unit of an external host device 400 connected to the printer 1, instead of or in addition to the operation unit 4.

[0062] <Drive coupling mechanism> Using Figures 8, 9, and 10, the drive coupling mechanism 120, which serves as a drive coupling means (drive coupling section) for transmitting driving force from the drive motor 5 to the waste toner transport screw 113 in this embodiment, will be explained. Figure 9 is a perspective view of the drive coupling mechanism 120 in this embodiment. Figure 10 is an exploded perspective view of the drive coupling mechanism 120 in this embodiment.

[0063] As shown in Figure 8, the waste toner transport screw 113 and the drive roller 46 are driven and connected by a drive coupling mechanism 120 provided on the transfer unit 40. The drive coupling mechanism 120 is provided on the left end of the drive roller 46 in the direction of its rotation axis. As shown in Figures 9 and 10, the drive coupling mechanism 120 is composed of a movable gear 121, a fixed gear 122, a detection lever 123, a biasing spring 124, a cover member 125, a drive gear 126, and an idler gear 127.

[0064] The movable gear 121 is a drive transmission member that receives driving force from the drive roller 46 side and is provided to be movable along its rotation axis. As will be described later, the movable gear 121 is movable between a first position and a second position, in which its relative position to the fixed gear 122 in the rotation axis direction is different, in conjunction with the change in the relative position of the fixed gear 122 with respect to the movable gear 121 in the rotation direction according to the magnitude of the rotation load torque of the waste toner transport screw 113. The fixed gear 122 is a drive transmission member that engages with the movable gear 121 to receive driving force from the movable gear 121 and also engages with the waste toner transport screw gear 113a provided on the waste toner transport screw 113 to transmit driving force to the waste toner transport screw 113. The waste toner transport screw gear 113a is provided at one end (the left and front end) in the rotation axis direction of the waste toner transport screw 113, on the rotation axis of the waste toner transport screw 113, so as to rotate integrally with the waste toner transport screw 113. The detection lever 123 is a detection member for detecting the movement of the movable gear 121 by moving integrally with the movable gear 121 along the rotation axis direction of the movable gear 121, as will be described later. The detection lever 123 has a lever portion 123a and a lever support portion 123b, the lever support portion 123b is fitted into a movable gear recess 121f provided in the movable gear 121. As a result, the detection lever 123 is held on the movable gear 121 so as to be rotatable relative to the movable gear 121, maintaining the position of the lever portion 123a in the rotation direction of the movable gear 121. The biasing spring 124 is a biasing member (in this embodiment, an elastic member, which is a compression coil spring) that acts as a biasing means to bias the movable gear 121 toward the fixed gear 122 along the rotation axis direction of the movable gear 121 via the detection lever 123. The cover member 125 is a holding member that has the function of holding the drive coupling mechanism 120 to the transfer frame 48, and is fixed to the transfer frame 48. The drive gear 126 is provided at one end (the left end) in the direction of the rotation axis of the drive roller 46, on the rotation axis 46a of the drive roller 46, so as to rotate integrally with the drive roller 46.The idler gear 127 engages with the drive gear 126 to receive driving force from the drive gear 126, and also engages with the movable gear 121 to transmit driving force to the movable gear 121. In other words, the drive gear 126 transmits drive to the movable gear 121 via the idler gear 127. Driving force is input from the drive motor 5 to the drive roller 46 via a drive coupling part (not shown) provided, for example, at the other end (right end) in the direction of the rotation axis of the drive roller 46.

[0065] Here, the side of the fixed gear 122 opposite to the movable gear 121 in the direction of its rotation axis abuts against the wall of the transfer frame 48. The biasing spring 124 is positioned between the fixed cover member 125 and the detection lever 123, which is movable along the rotation axis of the movable gear 121 together with the movable gear 121. The movable gear 121 and the detection lever 123 are biased by the biasing spring 124 toward the fixed gear 122 along the rotation axis of the movable gear 121. In other words, the movable gear 121 and the detection lever 123 are positioned between the fixed gear 122 and the cover member 125 with degrees of freedom to move along the rotation axis of the movable gear 121.

[0066] Thus, the drive coupling mechanism 120 includes a movable gear 121 as a first rotating body (first member, rotating member) positioned on the input side of the rotational driving force, a fixed gear 122 as a second rotating body (second member, rotated member) provided coaxially and relatively rotatable with respect to the first rotating body and positioned on the output side of the rotational driving force, a biasing spring 124 as a biasing member (elastic member) that applies a biasing force (elastic force) in the direction of pressing the movable gear 121 against the fixed gear 122 along the rotation axis direction, and a detection lever 123 that can move together with the movable gear 121.

[0067] Figure 11 shows a perspective view and a front view in more detail of the movable gear 121 and the fixed gear 122 in this embodiment. Figure 11(a) is a perspective view showing the side of the movable gear 121 facing the fixed gear 122 in the direction of the rotation axis, and Figure 11(b) is a front view showing that side of the movable gear 121. Figure 11(c) is a perspective view showing the side of the fixed gear 122 facing the movable gear 121 in the direction of the rotation axis, and Figure 11(d) is a front view showing that side of the fixed gear 122. The movable gear 121 and the fixed gear 122 have cam shapes (cam-shaped portions) that engage with each other.

[0068] The movable gear 121 rotates in the direction of arrow R1 in the figure. The movable gear 121 has a cam shape along the rotational direction (circumferential direction) on the surface facing the fixed gear 122 in the direction of the rotation axis. The movable gear 121 has a first inclined surface 121a, a flat surface 121b, a first vertical wall 121c, a second vertical wall 121d, and a second inclined surface 121e. Of the first inclined surface 121a and the second inclined surface 121e, the first inclined surface 121a is located on the downstream side in the rotational direction of the movable gear 121, and the second inclined surface 121e is located on the upstream side in the rotational direction of the movable gear 121. The first inclined surface 121a is inclined with respect to the rotational axis of the movable gear 121 such that it approaches the fixed gear 122 as it moves upstream in the rotational direction of the movable gear 121. Furthermore, the second inclined portion 121e is inclined with respect to the rotation axis direction of the movable gear 121 such that it moves away from the fixed gear 122 as it moves upstream in the rotation direction of the movable gear 121. A convex portion 121h having a first vertical wall portion 121c, a second vertical wall portion 121d, and a flat portion 121b is provided on the fixed gear 122 side surface of the base portion 121g on which the first inclined portion 121a and the second inclined portion 121e are formed. The first vertical wall portion 121c and the second vertical wall portion 121d each extend along the rotation axis direction of the movable gear 121 (approximately parallel in this embodiment). Of the first vertical wall portion 121c and the second vertical wall portion 121d, the first vertical wall portion 121c is provided on the downstream side in the rotation direction of the movable gear 121, and the second vertical wall portion 121d is provided on the upstream side in the rotation direction of the movable gear 121. The planar portion 121b extends between the first vertical wall portion 121c and the second vertical wall portion 121d along a plane that intersects (approximately perpendicular in this embodiment) with the rotation axis direction of the movable gear 121. The movable gear 121 also has a gear portion 121i on its outer circumference.

[0069] The fixed gear 122 rotates in the direction of arrow R2 in the figure. The fixed gear 122 has a cam shape along the rotational direction (circumferential direction) on the side of the movable gear 121 in the direction of the rotation axis. The fixed gear 122 has a first fixed inclined surface portion 122a, a first fixed flat surface portion 122b, a first fixed vertical wall portion 122c, a second fixed vertical wall portion 122d, a second fixed inclined surface portion 122e, and a second fixed flat surface portion 122f. Of the first fixed inclined surface portion 122a and the second fixed inclined surface portion 122e, the first fixed inclined surface portion 122a is provided on the upstream side in the rotational direction of the fixed gear 122, and the second fixed inclined surface portion 122e is provided on the downstream side in the rotational direction of the fixed gear 122. The first fixed inclined surface portion 122a is inclined with respect to the rotational axis direction of the fixed gear 122 such that it moves away from the movable gear 122 as it moves upstream in the rotational direction of the fixed gear 122. Furthermore, the second fixed inclined surface 122e is inclined with respect to the rotation axis direction of the fixed gear 122 such that it approaches the movable gear 121 as it moves upstream in the rotation direction of the fixed gear 122. A fixed convex shape portion 122h having a first fixed vertical wall portion 122c and a second fixed vertical wall portion 122d is provided on the movable gear 121 side surface of the fixed base portion 122g on which the first fixed inclined surface portion 122a and the second fixed inclined surface portion 122e are formed. The first fixed vertical wall portion 122c and the second fixed vertical wall portion 122d each extend along the rotation axis direction of the fixed gear 122 (approximately parallel in this embodiment). Of the first fixed vertical wall portion 122c and the second fixed vertical wall portion 122d, the first fixed vertical wall portion 122c is provided on the upstream side in the rotation direction of the fixed gear 122, and the second fixed vertical wall portion 122d is provided on the downstream side in the rotation direction of the fixed gear 122. The first fixed plane portion 122b and the second fixed plane portion 122f each extend along a plane that intersects (approximately perpendicular in this embodiment) with the rotation axis direction of the fixed gear 122. Of the first fixed plane portion 122b and the second fixed plane portion 122f, the first fixed plane portion 122b is provided on the upstream side in the rotation direction of the fixed gear 122, and the second fixed plane portion 122f is provided on the downstream side in the rotation direction of the fixed gear 122. The first fixed plane portion 122b and the second fixed plane portion 122f are provided on the upstream and downstream sides of the fixed convex shape portion 122h in the rotation direction of the fixed gear 122. The fixed gear 122 also has a gear portion 122i on its outer circumference.

[0070] In this embodiment, the movable gear 121 is also provided with the same cam shape as described above on the opposite side of the rotation axis of the movable gear 121 (at a position shifted 180 degrees in the rotational direction). Similarly, in this embodiment, the fixed gear 122 is also provided with the same cam shape as described above on the opposite side of the rotation axis of the fixed gear 122 (at a position shifted 180 degrees in the rotational direction).

[0071] Figure 12 is a cross-sectional view of the cam shapes of the movable gear 121 and fixed gear 122, cut along the dashed lines in Figures 11(b) and 11(d), schematically illustrating the operation of the drive coupling mechanism 120 during the rotational operation of the drive roller 46. Figures 12(a), 12(b), and 12(c) show the state of the movable gear 121 and fixed gear 122 when the amount of waste toner in the waste toner collection container 10 (rotational load torque of the waste toner transport screw 113) is different, as will be described later.

[0072] The movable gear 121 is biased by a biasing spring 124 with a spring force (spring pressure) Fs toward the fixed gear 122 along the rotation axis direction of the movable gear 121. When the movable gear 121 receives a drive input and rotates in the direction of arrow R1, the first inclined surface 121a and the first fixed inclined surface 122a come into contact, and the movable gear 121 receives a reaction force Ft corresponding to the magnitude of the rotational load torque of the fixed gear 122. Figure 12(a) shows a state in which the amount of waste toner in the waste toner collection container 10 is less than a predetermined amount (here, this state is also called the "normal state"). In this state, since the amount of waste toner in the waste toner collection container 10 is less than a predetermined amount, the rotational load torque of the fixed gear 122 that receives the transport resistance of the waste toner is smaller than a predetermined value. In other words, since the reaction force Ft acting on the movable gear 121 is smaller than the spring force Fs, the first inclined surface 121a and the first fixed inclined surface 122a come into contact (engage), and the driving force is transmitted from the movable gear 121 to the fixed gear 122. The fixed gear 122 then rotates in the direction of arrow R2.

[0073] When the amount of waste toner in the waste toner collection container 10 reaches a predetermined amount (near full in this embodiment), the rotational load torque of the fixed gear 122 increases, and the reaction force Ft acting on the movable gear 121 balances the spring force Fs. As the amount of waste toner in the waste toner collection container 10 increases, the first inclined surface 121a and the first fixed inclined surface 122a slide relative to each other, as shown in Figure 12(b). As a result, the movable gear 121 moves in the opposite direction to the biasing direction of the biasing spring 124 (away from the fixed gear 122 along the rotation axis direction of the movable gear 121).

[0074] Subsequently, as shown in Figure 12(c), the first inclined surface 121a and the first fixed inclined surface 122a become separated. Then, as shown in Figure 12(c), the flat surface 121b and the first fixed flat surface 122b come into contact (engage), and the first vertical wall 121c and the first fixed vertical wall 122c come into contact (engage). In this way, when the amount of waste toner in the waste toner collection container 10 exceeds a predetermined amount, the first vertical wall 121c and the first fixed vertical wall 122c come into contact, and driving force is transmitted from the movable gear 121 to the fixed gear 122. That is, as long as the movable gear 121 is rotated in the direction of arrow R1, the movable gear 121 will not return to the state shown in Figure 12(a).

[0075] In this embodiment, both the first inclined surface portion 121a and the first fixed inclined surface portion 122a, which are in contact with each other, are inclined surfaces with respect to the rotation axis direction of the movable gear 121. However, at least one of them may be such an inclined surface. For example, one may be an inclined surface with respect to the rotation axis direction of the movable gear 121, and the other may be a rib shape or boss shape that contacts that surface. Also, in this embodiment, both the first vertical wall portion 121c and the first fixed vertical wall portion 122c, which are in contact with each other, are surfaces that are substantially parallel to the rotation axis direction of the movable gear 121. However, at least one of them may be such a surface. For example, one may be an surface that is substantially parallel to the rotation axis direction of the movable gear 121, and the other may be a rib shape or boss shape that contacts that surface. Furthermore, in this embodiment, the planar portion 121b, which serves as a restricting portion on the movable gear 121, contacts the first fixed planar portion 122b of the fixed gear to restrict the phase change of the fixed gear 122. However, as can be seen from Figure 12(c), the regulating portion (the flat portion at the top of the fixed convex shape portion 122h) provided on the fixed gear 122 may contact the movable gear 121 to restrict the phase change of the fixed gear 122. In other words, the regulating portion only needs to be provided on at least one of the movable gear 121 or the fixed gear 121.

[0076] <Method for detecting near-full capacity> Using Figures 13 and 14, the detection mechanism 100, which serves as a detection means (detection unit) capable of detecting the movement of the movable gear 121 in the rotation axis direction, will be described. Figure 13 is a perspective view showing the detection mechanism 100 in this embodiment. Figure 14 is a cross-sectional view showing the detection mechanism 100 in this embodiment. In this embodiment, the detection mechanism 100 is capable of detecting the movement of the movable gear 121 in the rotation axis direction, thereby enabling detection that the rotational load torque of the waste toner transport screw 113 exceeds a predetermined value (overload condition).

[0077] As shown in Figures 13 and 14, the detection flag 130 and the detection sensor 131 are attached to and held by a sensor holder 132 provided on the main body side plate 1g, which is a side plate of the device body 1a. The detection flag 130 has a flag rotation axis 130a, a movable receiving portion 130b that can contact the lever portion 123a of the detection lever 123 provided on the drive coupling mechanism 120, and a light-shielding portion 130c that can enter and retract from the detection area 131c of the detection sensor 131. The detection flag 130 is attached to the sensor holder 132 so as to be rotatable around the flag rotation axis 130a, by having the flag rotation axis 130a rotatably supported by the sensor holder 132. Furthermore, the orientation of the detection flag 130 is maintained by a spring and a stopper (not shown) such that the movable receiving portion 130b moves toward the detection lever 123 and the light-shielding portion 130c is retracted from the detection area 131c of the detection sensor 131 (at least the optical axis of the detection light). In other words, the orientation of the detection flag 130 is maintained in the state shown in Figure 14(a). In this embodiment, the detection sensor 131 constituting the detection means is composed of a light-shielding and light-transmitting detection sensor (photosensor). The detection sensor 131 is configured in a U-shape in cross-section and has a light-emitting portion 131a, a light-receiving portion 131b, and a detection area 131c formed between the light-emitting portion 131a and the light-receiving portion 131b. The detection area 131c constitutes the optical path of the detection light from the light-emitting portion 131a toward the light-receiving portion 131b and allows the light-shielding portion 130c of the detection flag 130 to be located there. In this embodiment, the detection mechanism 100 is configured to include a detection flag 130 and a detection sensor 131. In this embodiment, the detection mechanism 100 can detect whether the position of the movable gear 121 in the direction of the rotation axis is in a first position (a state in which the rotation load torque is less than a predetermined value) or a second position (a state in which the rotation load torque is greater than or equal to a predetermined value) by having the detection sensor 131 detect the state of light shielding and transmission of detection light.

[0078] Figures 13(a) and 14(a) show the state where the amount of waste toner in the waste toner collection container 10 is less than a predetermined amount. In other words, Figures 13(a) and 14(a) show the normal state in which the movable gear 121 and the fixed gear 122 are engaged at the first inclined surface portion 121a and the first fixed inclined portion 122a. Figures 13(b) and 14(b) show the state in which the amount of waste toner in the waste toner collection container 10 has reached a predetermined amount, i.e., the near-full state. In other words, Figures 13(b) and 14(b) show the state in which the movable gear 121 and the fixed gear 122 are in contact at the flat portion 121b and the first fixed flat portion 122b, and also at the first vertical wall portion 121c and the first fixed vertical wall portion 122c.

[0079] In this embodiment, as the movable gear 121 moves in the direction of its rotation axis, the detection lever 123 contacts the detection flag 130, causing the detection flag 130 to rotate around the pivot axis 130a, thereby shielding or transmitting light to the detection sensor 131. More specifically, when the amount of waste toner in the waste toner collection container 10 shown in Figures 13(a) and 14(b) is less than a predetermined amount, the detection lever 123 is separated from the movable receiving portion 130b of the detection flag 130. The light-shielding portion 130c of the detection flag 130 is retracted from the detection area 131c of the detection sensor 131 (at least the optical axis of the detection light). As shown in Figures 13(b) and 14(b), when the amount of waste toner in the waste toner collection container 10 reaches a predetermined amount, the movable gear 121 and the detection lever 123 move along the rotation axis direction of the movable gear 121 due to the aforementioned operation. As this movement occurs, the lever portion 123a of the detection lever 123 comes into contact with the movement receiving portion 130b of the detection flag 130, causing the detection flag 130 to rotate around the flag rotation axis 130a. This causes the light-shielding portion 130c of the detection flag 130 to enter the detection area 131c of the detection sensor 131, blocking the optical axis of the detection light from the detection sensor 131. In this way, by detecting the light-shielding state of the detection sensor 131, the detection mechanism 100 can detect that the waste toner collection container 10 is nearly full. In other words, the detection sensor 131 can transition between a first state, a transparent state, and a second state, a light-shielding state. The detection flag member 130 causes the detection sensor 131 to transition between a light-shielding state and a light-transmitting state. The detection flag 130 causes the detection sensor 131 to be in a light-shielding state by shielding the optical path of the detection sensor 131, and causes the detection sensor 131 to be in a light-transmitting state by opening the optical path. The detection sensor 131 outputs different detection signals depending on whether the light is blocked or transmitted. In this embodiment, the output signal (detection signal) of the detection sensor 131 is set to OFF when light is transmitted and ON when light is blocked. This detection signal is input to the control unit 3. As a result, the control unit 3 can determine (detect) that the waste toner collection container 10 is nearly full.

[0080] Figure 15 shows an example of the detection pattern of the detection signal output from the detection sensor 131 when the detection mechanism 100 detects a near-full state (near-full detection). Under normal conditions while the drive roller 46 is rotating, the detection sensor 131 outputs an OFF signal. Figure 15(a) shows the detection pattern in this case. When the amount of waste toner in the waste toner collection container 10 approaches a predetermined amount, the detection sensor 131 outputs an ON signal through the operation shown in Figure 12(b). However, since the state of waste toner in the waste toner collection container 10 is not always stable, if the transport resistance of the waste toner transport screw 113 decreases due to factors such as vibration, the rotational load torque of the fixed gear 122 decreases, and the movable gear 121 may return to the state shown in Figure 12(a). Figure 15(b) shows the detection pattern in this case.

[0081] Figure 16 is a flowchart of near-full detection in this embodiment. The control unit 3 controls the drive motor 5 to start up, for example, when the image forming operation starts (S101). When the control unit 3 detects an ON signal from the detection sensor 131 (S102: Yes), it starts counting the near-full confirmation time T1 and determines whether to continue detecting the ON signal during the near-full confirmation time T1 (S102, S103). In other words, the control unit 3 determines whether the near-full confirmation time T1 has elapsed while an ON signal is being detected. The near-full confirmation time T1 is set in advance as the time during which an ON signal that can be determined to indicate a near-full state with sufficient accuracy continues. Then, if the control unit 3 continues to detect the ON signal during the near-full confirmation time T1 (S103: Yes), it detects that the near-full state is present and provides a near-full notification (S104). The control unit 3 also controls the drive motor 5 to stop, for example, when the image forming operation ends (S105). On the other hand, if the control unit 3 detects an OFF signal before the near-full confirmation time T1 has elapsed, or if it does not detect an ON signal from the detection sensor 131 (S102: No), it proceeds to the process in S105.

[0082] In Figure 15(b), at timings t1 and t2, the detection sensor 131 outputs an ON signal, but since it outputs an OFF signal before the near-full confirmation time T1 has elapsed, the control unit 3 can determine that it is not near-full. Then, if the detection sensor 131 outputs an ON signal during the near-full confirmation time T1 (from timing t3 to timing t4), the control unit 3 can determine that it is near-full. In this way, by detecting near-full after the near-full confirmation time T1 has elapsed, it is possible to reduce the possibility of issuing a replacement warning earlier than the originally defined replacement life by detecting the near-full state while the rotational load torque of the fixed gear 122 is unstable.

[0083] <Method for detecting replacement with a new product> Next, we will explain a new replacement detection method, which is a method for detecting when the waste toner collection container 10 (transfer unit 40 in this embodiment) has been replaced with a new one. Here, the process of determining whether or not the waste toner collection container 10 (transfer unit 40 in this embodiment) has been replaced with a new one is also referred to as "new replacement detection."

[0084] In this embodiment, since the waste toner collection container 10 is located inside the transfer unit 40, the waste toner collection container 10 can be replaced with a new one by removing the transfer unit 40 from the main body 1a of the device, as shown in Figure 5.

[0085] Figure 17 is a schematic diagram similar to Figure 12, illustrating the operation of the drive coupling mechanism 120 when a new replacement is detected. Figure 17(a) shows the positional relationship between the movable gear 121 and the fixed gear 122 when the transfer unit 40 is in a new condition. That is, in the new condition of the transfer unit 40, the movable gear 121 and the fixed gear 122 are mounted on the transfer unit 40 such that the second vertical wall portion 121d and the second fixed vertical wall portion 122d are in contact, and the flat portion 121b and the second fixed flat portion 122f are in contact. This positional relationship between the movable gear 121 and the fixed gear 122 is maintained by the biasing force of the biasing spring 124. When the drive roller 46 starts rotating, the flat portion 121b and the second fixed flat portion 122f slide relative to each other, and the movable gear 121 rotates in the direction of arrow R1. When the flat portion 121b and the second fixed flat portion 122f separate, as shown in Figure 17(b), the second inclined portion 121e and the second fixed inclined portion 122e come into contact, and the movable gear 121 moves in the biasing direction of the biasing spring 124 (towards the fixed gear 122 along the rotation axis direction of the movable gear 121). Then, as shown in Figure 17(c), the first inclined portion 121a and the first fixed inclined portion 122a engage, and the system transitions to the normal state in which driving force is transmitted from the movable gear 121 to the fixed gear 122.

[0086] The process of detecting replacement with a new unit in this embodiment will be explained using Figures 18 and 19. Figure 18 is a flowchart of the new unit replacement detection in this embodiment. Figure 19 shows an example of a detection pattern when detecting replacement with a new unit in this embodiment. In this embodiment, the transfer unit 40 is replaced when the printer 1 is powered off or when the door 20 is open. Therefore, in this embodiment, new unit replacement detection is performed when it is detected that the printer 1 is powered on or that the door 20 is closed. In this embodiment, the control unit 3 can detect that the door 20 is closed based on a detection signal indicating the open / closed state of the door 20, which is input from a switch (not shown) that serves as an open / closed door detection means for the door 20 provided on the printer 1.

[0087] When the control unit 3 detects that the printer 1 is powered on or that the door 20 is closed (S201), it determines whether or not it has detected an ON signal from the detection sensor 131 (S202). If the control unit 3 detects an ON signal from the detection sensor 131 (S202: Yes), it controls the drive motor 5 to start (S203). Next, the control unit 3 determines whether or not it has detected an OFF signal from the detection sensor 131 (S204). If the control unit 3 detects an OFF signal (S204: Yes), it starts counting the new product confirmation time T2 and determines whether or not to continue detecting the OFF signal during the new product confirmation time T2 (S204, S205). In other words, the control unit 3 determines whether or not the new product confirmation time T2 has elapsed while an OFF signal is being detected. The new product confirmation time T2 is preset as the time during which an OFF signal continues that allows the transfer unit 40 to be determined to be new with sufficient accuracy. Then, if the control unit 3 continuously detects an OFF signal during the new unit confirmation time T2 (S205: Yes), it detects that the transfer unit 40 is new and executes a predetermined process for when the transfer unit 40 has been replaced with a new one (S206). This predetermined process includes, for example, resetting (canceling) the near-full detection state and the full detection state, and resetting the life counter of the transfer unit 40 to its initial value (e.g., zero). The control unit 3 also controls the drive motor 5 to stop, thereby ending the new unit replacement detection (S207). On the other hand, if the control unit 3 does not detect an OFF signal from the detection sensor 131 in S204 (S204: No), it waits for the pre-set new unit detection time to elapse (S204, S208), then proceeds to the process in S207, ending the new unit replacement detection. The new unit detection time is pre-set as a time (predetermined period) that allows for a sufficiently accurate determination of whether or not the transfer unit 40 is new (it may be set similarly to the near-full confirmation time T1 mentioned above). In this case, the waste toner collection container 10 is nearly full or full, and the transfer unit 40 is not new. Also, if the control unit 3 does not detect an ON signal from the detection sensor 131 in S202 (S202: No), it proceeds to process S207 and terminates the new unit replacement detection. In this case, the waste toner in the waste toner collection container 10 is in a normal state with less than a predetermined amount, and the transfer unit 40 is not new.

[0088] Figure 19(a) shows the detection pattern immediately after the transfer unit 40 has been replaced with a new one. When the printer 1 is powered on, the detection sensor 131 outputs an ON signal, and the detection sensor 131 outputs an OFF signal almost simultaneously with the start timing t5 of the drive roller 46. Subsequently, if the detection sensor 131 outputs an OFF signal until the new unit confirmation time T2 has elapsed (until timing t6), the control unit 3 can determine that the transfer unit 40 has been replaced with a new one. The control unit 3 can then perform predetermined processing, such as resetting the near-full or full state of the waste toner collection container 10.

[0089] Figure 19(b) shows the detection pattern when the waste toner collection container 10 is nearly full or the transfer unit 40 is full and mounted on the device body 1a, and the printer 1 is turned on or the door 20 is closed. As mentioned above, after the near-full state is detected, the drive coupling mechanism 120 enters the state shown in Figure 12(c) and does not return to the state shown in Figure 12(a). Therefore, when the transfer unit 40 is mounted on the device body 1a after the near-full state has been detected, the detection sensor 131 always outputs an ON signal. In this case, the control unit 3 can determine that the waste toner collection container 10 (transfer unit 40) has not been replaced with a new one.

[0090] Figure 19(c) shows an example of a detection pattern when a transfer unit 40 is mounted on the device body 1a and the amount of waste toner in the waste toner collection container 10 is near a predetermined amount. The detection sensor 131 outputs an ON signal when new toner replacement detection is initiated, and then outputs an OFF signal (timing t7). However, before the new toner confirmation time T2 has elapsed (timing t8), a near-full state is detected, and the sensor outputs an ON signal again.

[0091] Furthermore, if a transfer unit 40 with less than a predetermined amount of waste toner in the waste toner collection container 10 is installed in the main body 1a of the device, the detection pattern will be as shown in Figure 15(a).

[0092] In other words, the control unit 3 can determine (detect) whether the transfer unit 40 (waste toner collection container 10) attached to the device body 1a is a new transfer unit 40 (waste toner collection container 10) based on the detection pattern acquired in the new unit replacement detection. More specifically, in this embodiment, the control unit 3 can determine (detect) whether the transfer unit 40 attached to the device body 1a is a transfer unit 40 with less than a predetermined amount of waste toner in the waste toner collection container 10 (normal state), a new transfer unit 40 (state where no waste toner is contained in the waste toner collection container 10), or a transfer unit 40 with more than a predetermined amount of waste toner in the waste toner collection container 10 (near full state or full state) based on the detection pattern acquired in the new unit replacement detection.

[0093] Thus, the image forming apparatus (printer) 1 of this embodiment comprises: an apparatus body 1a having an image forming unit (cartridge) P that forms an image with toner, a drive source (drive motor) 5 that generates driving force, and a detection unit (detection mechanism) 100 that can take on a first state and a second state and outputs a detection signal corresponding to the first state and the second state, respectively; and a detachable replacement unit (transfer unit) 40 that can be attached to the apparatus body 1a, comprising a rotating member (waste toner transport screw) 113, a first rotating body (movable gear) 121 that rotates when driving force is input from the drive source 5, and a second rotating body (fixed gear) 12 that is provided coaxially with the first rotating body 121, rotates when driving force is transmitted by the first rotating body 121, and transmits driving force toward the rotating member 113. The replacement unit 40 includes a first rotating body 121 and a biasing member (biasing spring) 124 that biases the first rotating body 121 relative to the second rotating body 122 along the rotation axis direction of the first rotating body 121. The first rotating body 121 is movable between a first position (Figures 12(a), 17(c)) and a second position (Figures 12(c), 17(a)), where the relative position of the first rotating body 121 relative to the second rotating body 122 in the rotation direction of the first rotating body 121 is different, in conjunction with the change in the relative position of the second rotating body 122 relative to the first rotating body 121 in the rotation direction of the first rotating body 121 according to the magnitude of the rotation load torque of the rotating member 113. The detection unit 100 changes state between the first state and the second state in accordance with the movement of the first rotating body 121 between the first and second positions. In this embodiment, the detection pattern of the detection signal output by the detection unit 100 during a predetermined period (new product detection time) after the drive source 5 is started with the replacement unit 40 attached to the device body 1a differs depending on whether the first rotating body 121 is in the first position and the rotational load torque of the rotating member 113 is less than a predetermined value when the drive source 5 is started (normal state), whether the first rotating body 121 is in the second position and the rotational load torque of the rotating member 113 is less than a predetermined value when the drive source 5 is started (new product state), or whether the first rotating body 121 is in the second position and the rotational load torque of the rotating member 113 is greater than or equal to a predetermined value when the drive source 5 is started (near full state or full state).

[0094] In this embodiment, the replacement unit 40 includes a waste toner collection container 10 for storing the waste toner collected in the main body 1a of the device, and a waste toner transport member (waste toner transport screw) 113 for transporting the waste toner stored in the waste toner collection container 10, and the rotating member is the waste toner transport member 113. In this embodiment, the rotational load torque of the waste toner transport member 113 is less than the predetermined value when the amount of waste toner stored in the waste toner collection container 10 is less than the predetermined amount, and is greater than or equal to the predetermined value when the amount of waste toner stored in the waste toner collection container 10 is equal to or greater than the predetermined amount, and the image forming apparatus 1 has a control unit 3 that can detect whether the amount of waste toner stored in the waste toner collection container 10 is equal to or greater than the predetermined amount based on a detection signal output by the detection unit 100. In this embodiment, the new replacement unit 40 is installed such that the first rotating body 121 is in the second position before the rotation of the rotating member 113 begins, and the control unit 3 can detect whether the replacement unit 40 mounted on the device body 1a is new based on the detection pattern. In this embodiment, the control unit 3 detects that the replacement unit 40 mounted on the device body 1a is new when the detection pattern is obtained in which the first rotating body 121 is in the second position and the rotation load torque of the rotating member 113 is less than the predetermined value when the drive source 5 starts to drive. In this embodiment, the replacement unit 40 includes an endless belt (intermediate transfer belt) 41 on which an image formed with toner by the image forming unit P is transferred, a cleaning unit 43 that removes toner from the belt 41, and a waste toner collection container 10 that contains the toner removed from the belt 41 by the cleaning unit 43.

[0095] Furthermore, in this embodiment, at least one of the first rotating body 121 and the second rotating body 122 has a cam-shaped portion (such as a first inclined surface portion 121a, a first fixed inclined surface portion 122a, etc.) that can move the relative position of the first rotating body 121 with respect to the second rotating body 122 in the direction of the rotation axis of the first rotating body 121 from the first position to the second position. In this embodiment, the cam-shaped portion (first inclined surface portion 121a, flat portion 121b, first vertical wall portion 121c, first fixed inclined surface portion 122a, first fixed flat portion 122b, first fixed vertical wall portion 122c) is configured such that when the drive source 5 is driven with the replacement unit 40 mounted on the device body 1a, the position of the first rotating body 121 is maintained at the first position if the rotational load torque of the rotating member 113 is less than the predetermined value, and when the rotational load torque of the rotating member 113 changes from a rotational load torque less than the predetermined value to a rotational load torque greater than or equal to the predetermined value, the position of the first rotating body 121 is moved from the first position to the second position and maintained at the second position.

[0096] As explained above, according to this embodiment, even if, for example, the waste toner collection container 10 is simply attached or detached before it is detected to be nearly full, it is possible to correctly detect whether or not the waste toner collection container 10 has been replaced with a new one. Furthermore, since it is not necessary to separately install a waste toner collection container 10 fullness detection means and a new replacement detection means in the printer 1, the possibility of increasing the size and cost of the device due to an increase in the number of parts can be reduced. In other words, according to this embodiment, it is possible to detect when the replacement unit needs to be replaced and to detect whether or not the replacement unit has been replaced with a new one, with a simple configuration that is advantageous in suppressing increases in the size and cost of the device.

[0097] [Example 2] Next, other embodiments of the present invention will be described. The basic configuration and operation of the image forming apparatus in this embodiment are the same as those of the image forming apparatus in Embodiment 1. Therefore, elements having the same or corresponding functions or configurations as those of the image forming apparatus in Embodiment 1 are denoted by the same reference numerals as in Embodiment 1, and detailed descriptions are omitted.

[0098] <Drive transmission mechanism> Figure 20 shows a perspective view and a front view of the movable gear 221 and fixed gear 222 in this embodiment. Figure 20(a) is a perspective view showing the side of the movable gear 221 facing the fixed gear 222 in the direction of the rotation axis, and Figure 20(b) is a front view showing that side of the movable gear 221. Figure 20(c) is a perspective view showing the side of the fixed gear 222 facing the movable gear 221 in the direction of the rotation axis, and Figure 20(d) is a front view showing that side of the fixed gear 222. The movable gear 221 and fixed gear 222 have cam shapes (cam-shaped portions) that engage with each other. The drive transmission mechanism 220 in this embodiment has the movable gear 221 and fixed gear 222 in this embodiment instead of the movable gear 121 and fixed gear 122 of the drive transmission mechanism 120 in Embodiment 1. In other respects, the configuration of the drive coupling mechanism 220 in this embodiment is substantially the same as that of the drive coupling mechanism 120 in Embodiment 1.

[0099] The movable gear 221 rotates in the direction of arrow R1 in the figure. The movable gear 221 has a cam shape along the rotational direction (circumferential direction) on the surface facing the fixed gear 222 in the direction of the rotation axis. In this embodiment, the movable gear 221 has a first inclined surface 221a, a flat surface 221b, and a second inclined surface 221c. Of the first inclined surface 221a and the second inclined surface 221c, the first inclined surface 221a is provided on the downstream side in the rotational direction of the movable gear 221, and the second inclined surface 221c is provided on the upstream side in the rotational direction of the movable gear 221. The first inclined surface 221a is inclined with respect to the rotational axis of the movable gear 221 such that it approaches the fixed gear 222 as it moves upstream in the rotational direction of the movable gear 221. Furthermore, the second inclined portion 221c is inclined with respect to the rotation axis direction of the movable gear 221 such that it moves away from the fixed gear 222 as it moves upstream in the rotation direction of the movable gear 221. A flat portion 221b is formed on the fixed gear 222 side surface of the convex portion 221d on which the first inclined portion 221a and the second inclined portion 221c are formed. The flat portion 221b extends between the first inclined portion 221a and the second inclined portion 221c along a plane that intersects (approximately perpendicular in this embodiment) with the rotation axis direction of the movable gear 221. The movable gear 221 also has a gear portion 221e on its outer circumference.

[0100] The fixed gear 222 rotates in the direction of arrow R2 in the figure. The fixed gear 222 has a cam shape on the side of the movable gear 221 in the direction of the rotation axis, along the direction of rotation (circumferential direction). In this embodiment, the fixed gear 222 has a first fixed inclined surface portion 222a, a fixed flat surface portion 222b, and a second fixed inclined surface portion 222c. Of the first fixed inclined surface portion 222a and the second fixed inclined surface portion 222c, the first fixed inclined surface portion 222a is provided on the upstream side in the direction of rotation of the fixed gear 222, and the second fixed inclined surface portion 222c is provided on the downstream side in the direction of rotation of the fixed gear 222. The first fixed inclined surface portion 222a is inclined with respect to the direction of rotation axis of the fixed gear 222 such that it moves away from the movable gear 222 as it moves upstream in the direction of rotation of the fixed gear 222. Furthermore, the second fixed inclined surface portion 222c is inclined with respect to the rotation axis direction of the fixed gear 222 such that it approaches the movable gear 221 as it moves upstream in the rotation direction of the fixed gear 222. A fixed flat surface portion 222b is formed on the movable gear 221 side surface of the fixed convex-shaped portion 222d on which the first fixed inclined surface portion 222a and the second fixed inclined surface portion 222c are formed. The fixed flat surface portion 222b extends between the first fixed inclined surface portion 222a and the second fixed inclined surface portion 222c along a plane that intersects (approximately perpendicular in this embodiment) with the rotation axis direction of the fixed gear 222. The fixed gear 222 also has a gear portion 222e on its outer circumference.

[0101] In other words, the movable gear 221 in this embodiment has a shape obtained by removing the first vertical wall portion 121c and the second vertical wall portion 121d (i.e., the convex shape portion 121h) from the movable gear 121 in Embodiment 1. Also, the fixed gear 222 in this embodiment has a shape obtained by removing the first fixed vertical wall portion 122c and the second fixed vertical wall portion 122d (i.e., the fixed convex shape portion 122h) from the fixed gear 122 in Embodiment 1.

[0102] In this embodiment, the movable gear 221 is also provided with the same cam shape as described above on the opposite side of the rotation axis of the movable gear 221 (at a position shifted 180 degrees in the rotation direction). Similarly, in this embodiment, the fixed gear 222 is also provided with the same cam shape as described above on the opposite side of the rotation axis of the fixed gear 222 (at a position shifted 180 degrees in the rotation direction).

[0103] Figure 21 is a cross-sectional view of the cam shapes of the movable gear 221 and the fixed gear 222, cut along the dashed lines in Figures 20(b) and 20(d), schematically illustrating the operation of the drive coupling mechanism 220 during the rotational movement of the drive roller 46.

[0104] Similar to Example 1, under normal conditions, the first inclined surface 221a of the movable gear 221 and the first fixed inclined surface 222a of the fixed gear 222 are in contact, and driving force is transmitted from the movable gear 221 to the fixed gear 222. When the amount of waste toner in the waste toner collection container 10 reaches a predetermined amount, the rotational load torque of the fixed gear 222 increases, and as shown in Figure 21(b), the first inclined surface 221a and the first fixed inclined surface 222a slide relative to each other, and the movable gear 221 moves in the opposite direction to the biasing direction of the biasing spring 124 (in the direction away from the fixed gear 222 along the rotation axis direction of the movable gear 221). Subsequently, as shown in Figure 21(c), the first inclined surface 221a and the first fixed inclined surface 222a become separated. Then, the flat surface 221b and the fixed flat surface 222b become in contact. If the movable gear 221 rotates further in the direction of arrow R1 from the state shown in Figure 21(c), the following occurs. That is, as shown in Figure 21(d), the second inclined surface 221c and the second fixed inclined surface 222c slide relative to each other, and the movable gear 221 moves in the biasing direction of the biasing spring 124 (in the direction toward the fixed gear 222 along the rotation axis of the movable gear 221). Then it returns to the state shown in Figure 21(a).

[0105] Thus, in this embodiment, when the reaction force Ft that the movable gear 221 receives in accordance with the magnitude of the rotational load torque of the fixed gear 122 is smaller than the spring force Fs, the movable gear 221 and the fixed gear 222 rotate in one direction while engaged, as shown in Figure 21(a). On the other hand, when the reaction force Ft increases and exceeds the spring force Fs, the movable gear 221 rotates while moving in the direction of the rotation axis against the biasing force of the biasing spring 124. Then, the state changes in the order of Figure 21(b), Figure 21(c), and Figure 21(d), and the operation of returning to the state of Figure 21(a) is repeated.

[0106] Figure 22 is a cross-sectional view showing a detection mechanism 100 capable of detecting the movement of the movable gear 221 in the rotation axis direction in this embodiment. As shown in Figure 22, the movable gear 221 and the fixed gear 222 are attached to the drive coupling mechanism 220. Then, similar to Embodiment 1, as the movable gear 221 moves in the rotation axis direction, the detection lever 123 moves, and the detection flag 130 rotates around the pivot axis 130a, thereby blocking or transmitting light to the detection sensor 131.

[0107] <Near full detection> Figure 23 shows an example of the detection pattern of the detection signal output from the detection sensor 131 when the detection mechanism 100 in this embodiment detects a near-full state. Under normal conditions while the drive roller 46 is rotating, the detection sensor 131 outputs an OFF signal. Figure 23(a) shows the detection pattern in this case. When the amount of waste toner in the waste toner collection container 10 approaches a predetermined amount, the detection sensor 131 repeatedly outputs ON signals and OFF signals alternately, as described above using Figure 21. Figure 23(b) shows the detection pattern in this case. At this time, depending on the rotation speed of the movable gear 221, the detection sensor 131 outputs ON signals and OFF signals a predetermined number of times or more within a predetermined time. This predetermined time is defined as the near-full confirmation time T3, and the ON signals and OFF signals are defined as pulse signals. One set of ON signals and OFF signals is counted as one pulse signal. The control unit 3 can determine that the waste toner collection container 10 is nearly full by detecting a predetermined number of pulse signals during the near-full confirmation time T3 (from timing t11 to timing t12). On the other hand, at timings t9 and t10 shown in Figure 23(b), the detection sensor 131 outputs an ON signal, but since it has not detected a predetermined number of pulse signals during the near-full confirmation time T3, the control unit 3 can determine that the waste toner collection container 10 is not nearly full. The near-full confirmation time T3 and the number of pulse signals are preset as a time and number that can determine the near-full state with sufficient accuracy.

[0108] Figure 24 is a flowchart of near-full detection in this embodiment. The control unit 3 controls the drive motor 5 to start up, for example, when the image forming operation starts (S301). When the control unit 3 detects the ON signal from the detection sensor 131 (S302:Yes), it starts counting the number of pulse signals (S303) and starts counting the near-full confirmation time T3 (S304). After the near-full confirmation time T3 has elapsed, the control unit 3 determines whether the number of pulse signals is greater than or equal to a predetermined number (S305). Then, if the number of pulse signals is greater than or equal to a predetermined number (S305:Yes), the control unit 3 detects that the car is in a near-full state and provides a near-full notification (S306). The control unit 3 also controls the drive motor 5 to stop, for example, when the image forming operation ends (S307). On the other hand, if the control unit 3 does not detect an ON signal from the detection sensor 131 in S302 (S302: No), and if the number of pulse signals in S305 is less than a predetermined number (S305: No), it proceeds to the process in S307.

[0109] In this way, by detecting the near-full state after the near-full confirmation time T3 has elapsed, it is possible to reduce the possibility of issuing a replacement warning earlier than the originally defined replacement life by detecting the near-full state while the rotational load torque of the fixed gear 222 is unstable.

[0110] <New product replacement detected> Figure 25 is a schematic diagram similar to Figure 21, illustrating the operation of the drive coupling mechanism 220 when a new replacement is detected in this embodiment. Figure 25(a) shows the positional relationship between the movable gear 221 and the fixed gear 222 when the transfer unit 40 is in a new condition. That is, in a new transfer unit 40, the movable gear 221 and the fixed gear 222 are mounted on the transfer unit 40 such that the flat portion 221b and the fixed flat portion 222b are in contact. This positional relationship between the movable gear 221 and the fixed gear 222 is maintained by the biasing force of the biasing spring 124. When the drive roller 46 starts rotating, the flat portion 221b and the fixed flat portion 222b slide relative to each other, and the movable gear 221 rotates in the direction of arrow R1. When the flat portion 221b and the fixed flat portion 222b separate, as shown in Figure 25(b), the second inclined portion 221c and the second fixed inclined portion 222c come into contact, and the movable gear 221 moves in the biasing direction of the biasing spring 124 (towards the fixed gear 222 along the rotation axis direction of the movable gear 221). Then, as shown in Figure 25(c), the first inclined portion 221a and the first fixed inclined portion 222a engage, and the gear transitions to the normal state in which driving force is transmitted from the movable gear 221 to the fixed gear 222.

[0111] The process of detecting a replacement with a new unit in this embodiment will be explained using Figures 26 and 27. Figure 26 shows an example of a detection pattern when detecting a replacement with a new unit in this embodiment. Figure 26 is a flowchart of the new unit replacement detection in this embodiment. In this embodiment, the transfer unit 40 is replaced when the printer 1 is powered off or the door 20 is open. Therefore, in this embodiment, new unit replacement detection is performed when it is detected that the printer 1 is powered on or that the door 20 is closed.

[0112] When the control unit 3 detects that the printer 1 is powered on or that the door 20 is closed (S401), it determines whether or not it has detected an ON signal from the detection sensor 131 (S402). If the control unit 3 detects an ON signal from the detection sensor 131 (S402: Yes), it controls the drive motor 5 to start (S403). Next, the control unit 3 determines whether or not it has detected an OFF signal from the detection sensor 131 (S404). If the control unit 3 detects an OFF signal (S404: Yes), it starts counting the new product confirmation time T4 and determines whether or not to continue detecting the OFF signal during the new product confirmation time T4 (S404, S405). In other words, the control unit 3 determines whether or not the new product confirmation time T4 has elapsed while an OFF signal is being detected. The new product confirmation time 42 is preset as the time during which an OFF signal continues that allows the transfer unit 40 to be determined to be new with sufficient accuracy. Then, if the control unit 3 continuously detects an OFF signal during the new unit confirmation time T4 (S405: Yes), it detects that the transfer unit 40 is new and executes a predetermined process for when the transfer unit 40 has been replaced with a new one (S406). This predetermined process includes, for example, resetting (canceling) the near-full detection state and the full detection state, and resetting the life counter of the transfer unit 40 to its initial value (e.g., zero). The control unit 3 also controls the drive motor 5 to stop, thereby ending the new unit replacement detection (S407). On the other hand, if the OFF signal from the detection sensor 131 does not continue during the new unit confirmation time T4 in S404 and S405, the control unit 3 waits for the pre-set new unit detection time to elapse (S404, S408), proceeds to the process in S407, and ends the new unit replacement detection. The new unit detection time is pre-set as a time that allows for a sufficiently accurate determination of whether or not the transfer unit 40 is new (it may be set the same as the near-full confirmation time T3 mentioned above). In this case, the waste toner collection container 10 is nearly full or full, and the transfer unit 40 is not new. Also, if the control unit 3 does not detect an ON signal from the detection sensor 131 in S402 (S402: No), it proceeds to process S407 and terminates the new unit replacement detection. In this case, the waste toner in the waste toner collection container 10 is in a normal state with less than a predetermined amount, and the transfer unit 40 is not new.

[0113] Figure 26(a) shows the detection pattern immediately after the transfer unit 40 has been replaced with a new one. When the printer 1 is powered on, the detection sensor 131 outputs an ON signal, and the detection sensor 131 outputs an OFF signal almost simultaneously with the start timing t13 of the drive roller 46. Subsequently, if the detection sensor 131 outputs an OFF signal until the new unit confirmation time T4 has elapsed (until timing t14), the control unit 3 can determine that the transfer unit 40 has been replaced with a new one. The control unit 3 can then perform predetermined processing, such as resetting the near-full or full state of the waste toner collection container 10.

[0114] Figure 26(b) shows the detection pattern when the waste toner collection container 10 is nearly full or the transfer unit 40 is full and mounted on the device body 1a, and the printer 1 is turned on or the door 20 is closed. As described above, after the near-full state is detected, the drive coupling mechanism 220 repeats the operation shown in Figures 21(a) to 21(d). Therefore, when the transfer unit 40 is mounted on the device body 1a after the near-full state is detected, the detection sensor 131 repeatedly outputs ON and OFF signals during the new unit confirmation time T4 (timing t15 to timing t16). In this case, the control unit 3 can determine that the waste toner collection container 10 (transfer unit 40) has not been replaced with a new one.

[0115] Furthermore, if a transfer unit 40 with less than a predetermined amount of waste toner in the waste toner collection container 10 is installed in the main body 1a of the device, the detection pattern will be as shown in Figure 23(a).

[0116] In other words, similar to Embodiment 1, the control unit 3 can determine (detect) whether the transfer unit 40 (waste toner collection container 10) attached to the device body 1a is a new transfer unit 40 (waste toner collection container 10) based on the detection pattern when detecting replacement with a new unit. More specifically, in this embodiment, the control unit 3 can determine (detect) whether the transfer unit 40 attached to the device body 1a is a transfer unit 40 with less than a predetermined amount of waste toner in the waste toner collection container 10 (normal state), a new transfer unit 40 (state where no waste toner is contained in the waste toner collection container 10), or a transfer unit 40 with more than a predetermined amount of waste toner in the waste toner collection container 10 (near full state or full state) based on the detection pattern. In this embodiment, when a new toner cartridge is replaced, if the waste toner collection container 10 is nearly full or full, the movable gear 221 may be in the second position (Figure 21(c)) or the first position (Figure 21(a)) when the drive motor 5 is started. However, even if the movable gear 221 is in the first position at the start of the new toner cartridge replacement detection, the movable gear 221 will repeatedly move to the second position and the first position during subsequent new toner cartridge replacement detections, and the detection signal from the detection sensor 131 will repeatedly switch between ON and OFF signals. Therefore, even in this case, the control unit 3 can detect that the transfer unit 40 mounted on the device body 1a is in a state where the waste toner collection container 10 is nearly full or full.

[0117] Thus, in this embodiment, at least one of the first rotating body (movable gear) 221 and the second rotating body (fixed gear) 222 has a cam-shaped portion (first inclined surface portion 221a, first fixed inclined surface portion 222a, etc.) that can move the relative position of the first rotating body 221 with respect to the second rotating body 222 in the direction of the rotation axis of the first rotating body 221 from a first position (Figure 21(a)) to a second position (Figure 21(c)). In this embodiment, the cam-shaped portion (first inclined surface portion 221a, flat portion 221b, second inclined surface portion 221c, first fixed inclined surface portion 222a, fixed flat portion 222b, second fixed inclined surface portion 222c) is configured such that when the drive source 5 is driven with the replacement unit 40 mounted on the device body 1a, the position of the first rotating body 221 is maintained at the first position if the rotational load torque of the rotating member 113 is less than a predetermined value, and when the rotational load torque of the rotating member 113 changes from a rotational load torque less than the predetermined value to a rotational load torque greater than or equal to the predetermined value, the position of the first rotating body 221 is moved from the first position to the second position, and then moved from the second position back to the first position, and this process is repeated.

[0118] As described above, the same effects as in Example 1 can be obtained with the configuration of this embodiment.

[0119] [others] Although the present invention has been described above with reference to specific embodiments, the present invention is not limited to the embodiments described above.

[0120] In the embodiments described above, the case in which the replacement unit is a waste toner collection container was explained as an example, but the invention is not limited to this. For example, it may be desirable to detect when an overload condition occurs in process means such as the toner transport screw of a replenishment device that supplies toner to a developing device, or the developing roller of a developing device. It may also be desirable to detect whether these are in a new condition or not. The present invention can also be applied to such other replacement units.

[0121] Furthermore, waste toner is not limited to residual toner remaining on the image carrier after the transfer process. For example, in an image forming apparatus, toner (developer including toner and carrier in the case of a two-component developer) may be discharged from the developer to refresh the developer in the developer unit. Also, adjustment toner images (patches) that are not transferred to the recording material may be formed on the image carrier. The waste toner collected in the waste toner collection container includes any of these toners (which may include carriers). In addition, the toner removed from the image carrier is not limited to the toner removed from the intermediate transfer belt, but may also include the toner removed from the photosensitive drum.

[0122] Furthermore, in the above-described embodiment, the state in which the rotational load torque of the waste toner transport screw exceeds a predetermined value was described as the state in which the waste toner collection container is nearly full. However, for example, it could also be the state in which the waste toner collection container is full.

[0123] Furthermore, in the above-described embodiment, it was explained that the waste toner transport screw receives driving force from a drive source that rotates the belt (drive roller), but the image forming apparatus may have a separate drive source that rotates the waste toner transport screw.

[0124] Furthermore, although the above embodiment described an example where a photosensor is used as the detection sensor, a mechanical switch that is turned ON / OFF by a flag may also be used as the detection sensor. [Explanation of symbols]

[0125] 1. Image forming apparatus 10 Waste toner collection container 40 Transfer Units 41 Intermediate transfer belt 43 Cleaning Department 46 drive rollers 100 detection mechanism 113 Waste Toner Transport Screw 120 Drive coupling mechanism 121 Movable Gear 122 Fixed Gear 123 Detection lever 124. Biasing spring 130 detection flag 131 Detection Sensor 220 Drive coupling mechanism 221 Movable Gear 222 Fixed Gear

Claims

1. The apparatus body comprises an image forming unit that forms an image with toner, a drive source that generates driving force, and a detection unit that can take on a first state and a second state and outputs a detection signal corresponding to the first state and the second state, A replacement unit that is detachable from the main body of the device, comprising: a rotating member; a first rotating body that rotates when a driving force is input from the drive source; a second rotating body provided coaxially with the first rotating body, which rotates when a driving force is transmitted by the first rotating body and transmits the driving force toward the rotating member; and a biasing member that biases the first rotating body relative to the second rotating body along the rotation axis direction of the first rotating body, It has, The first rotating body is movable between a first position and a second position, where the relative position of the first rotating body with respect to the second rotating body in the direction of the rotation axis is different, in conjunction with the change in the relative position of the second rotating body with respect to the first rotating body in the direction of rotation of the first rotating body, depending on the magnitude of the rotational load torque of the rotating member. The detection unit changes its state between the first state and the second state in response to the movement of the first rotating body between the first position and the second position. In the new replacement unit, the first rotating body is mounted such that it is in the second position before the rotation of the rotating member begins. An image forming apparatus characterized in that the detection pattern of the detection signal output by the detection unit during a predetermined period after the drive of the drive source is started while the replacement unit is mounted on the main body of the apparatus differs depending on whether the first rotating body is in the first position and the rotational load torque of the rotating member is less than a predetermined value when the drive of the drive source is started, whether the first rotating body is in the second position and the rotational load torque of the rotating member is less than the predetermined value when the drive of the drive source is started, or whether the first rotating body is in the second position and the rotational load torque of the rotating member is greater than or equal to the predetermined value when the drive of the drive source is started.

2. The replacement unit comprises a waste toner collection container for storing the waste toner collected in the main body of the device, and a waste toner transport member for transporting the waste toner stored in the waste toner collection container. The image forming apparatus according to claim 1, characterized in that the rotating member is the waste toner transport member.

3. The rotational load torque of the waste toner transport member is less than the predetermined value when the amount of waste toner contained in the waste toner collection container is less than a predetermined amount, and is greater than or equal to the predetermined value when the amount of waste toner contained in the waste toner collection container is equal to or equal to the predetermined amount. The image forming apparatus according to claim 2, characterized in that it has a control unit capable of detecting whether the amount of waste toner contained in the waste toner collection container is equal to or greater than a predetermined amount, based on a detection signal output by the detection unit.

4. The image forming apparatus according to claim 3, characterized in that the control unit can detect whether or not the replacement unit mounted on the main body of the apparatus is new, based on the detection pattern.

5. The image forming apparatus according to claim 4, characterized in that the control unit detects that the replacement unit mounted on the main body of the apparatus is new when the detection pattern is obtained in which the first rotating body is in the second position and the rotational load torque of the rotating member is less than the predetermined value when the drive source is started to drive.

6. The image forming apparatus according to any one of claims 2 to 5, characterized in that the replacement unit comprises an endless belt onto which an image formed with toner by the image forming unit is transferred, a cleaning unit for removing toner from the belt, and a waste toner collection container for storing the toner removed from the belt by the cleaning unit.

7. The image forming apparatus according to claim 1, characterized in that at least one of the first rotating body and the second rotating body has a cam-shaped portion capable of moving the relative position of the first rotating body with respect to the second rotating body in the direction of the rotation axis of the first rotating body from a first position to a second position.

8. The image forming apparatus according to claim 7, characterized in that the cam-shaped portion is configured such that, when the drive source is driven with the replacement unit mounted on the main body of the apparatus, if the rotational load torque of the rotating member is less than the predetermined value, the position of the first rotating body is maintained at the first position, and if the rotational load torque of the rotating member changes from a rotational load torque less than the predetermined value to a rotational load torque greater than or equal to the predetermined value, the position of the first rotating body is moved from the first position to the second position and maintained at the second position.

9. The image forming apparatus according to claim 7, characterized in that the cam-shaped portion is configured such that, when the drive source is driven with the replacement unit mounted on the main body of the apparatus, if the rotational load torque of the rotating member is less than the predetermined value, the position of the first rotating body is maintained at the first position, and when the rotational load torque of the rotating member changes from a rotational load torque less than the predetermined value to a rotational load torque greater than or equal to the predetermined value, the position of the first rotating body is moved from the first position to the second position, and then moved from the second position to the first position, and this process is repeated.

10. The detection signal includes a first level corresponding to the first state and a second level corresponding to the second state, The detection pattern during the predetermined period is When the drive source is started, if the first rotating body is in the first position and the rotational load torque of the rotating member is less than the predetermined value, the first level is indicated. If the first rotating body is in the second position and the rotational load torque of the rotating member is less than the predetermined value when the drive source is started, then the level changes from the second level to the first level within the predetermined period. When the drive source is started, if the first rotating body is in the second position and the rotational load torque of the rotating member is equal to or greater than the predetermined value, the second level is indicated within the predetermined period. The image forming apparatus according to feature 1.

11. The image forming apparatus according to claim 10, characterized in that when the drive source is started, the first rotating body is in the first position and the rotational load torque of the rotating member is less than the predetermined value, the detection pattern maintains the first level for the predetermined period of time.

12. The image forming apparatus according to claim 10 or 11, characterized in that when the drive source is started, the detection pattern when the first rotating body is in the second position and the rotational load torque of the rotating member is less than the predetermined value indicates the second level at the start of the drive source, and thereafter changes to the first level within the predetermined period.

13. The image forming apparatus according to claim 10 or 11, characterized in that when the drive source is started, the first rotating body is in the second position and the rotational load torque of the rotating member is greater than or equal to the predetermined value, the detection pattern maintains the second level for the predetermined period of time.

Images