Image forming apparatus

Abstract

An image forming apparatus includes a photosensitive drum, a charger to charge the photosensitive drum, a developing cartridge having a toner accommodating portion and a developing roller, a contact separation mechanism to move the developing roller between a contact position in contact with the photosensitive drum and a separation position separated from the photosensitive drum, a process motor to rotate the photosensitive drum and the developing roller, a drive transmission mechanism to transmit a driving force from the process motor to the developing roller when the developing roller is in the contact position and not to transmit the driving force to the developing roller when the developing roller is in the separation position, a high voltage power supply substrate to apply a voltage to charge the photosensitive drum to the charger, and a control portion. The control portion applies the voltage to the charger using the high voltage power supply substrate while rotating the photosensitive drum using the process motor in a state where the developing roller is in the separation position, and judges whether or not toner is consolidated in the toner accommodating portion based on the rotation of the process motor in a state where the developing roller is moved from the separation position to the contact position using the contact separation mechanism.

Description

Technical Field

[0001] This invention relates to an image forming apparatus for determining the solidification of toners. Background Technology

[0002] In the past, in image forming apparatuses with a developing cartridge that contains a developer container for holding toner and a developing roller that supplies toner to a photosensitive drum, the toner sometimes solidifies inside the developing cartridge when placed at a high temperature.

[0003] Japanese Patent Application Publication No. 2002-148886 discloses a technology that includes a motor for driving a toner stirring component, and that estimates the state of the toner and determines the solidification of the toner by comparing the rotational speed of the motor with an initially set target speed.

[0004] Patent Document 1: Japanese Patent Application Publication No. 2002-148886 Summary of the Invention

[0005] Patent Document 1 discloses a technique for determining toner solidification based on the speed of a motor that rotates a component in contact with the toner. On the other hand, an image forming apparatus is proposed, comprising a mechanism for contacting the developing roller with the photosensitive drum and for keeping the developing roller out of contact with the photosensitive drum. When the developing roller is in contact with the photosensitive drum, a driving force from a motor is transmitted to the developing roller to rotate it. In such an image forming apparatus, it is considered that by using the developing roller as the component in contact with the toner, the solidification of the toner can be determined based on the speed of the motor that rotates the developing roller. However, in such an image forming apparatus, if the developing roller is not in contact with the photosensitive drum, the developing roller does not rotate. Therefore, in order to detect the state of the toner in the developing cartridge as described in Patent Document 1, the developing roller needs to be rotated, and the toner moves from the developing roller to the photosensitive drum, resulting in the problem of useless consumption of toner in the developing cartridge.

[0006] The present invention was made to solve the aforementioned prior art problems, and its object is to provide an image forming apparatus in which, while the developing roller and the photosensitive drum are in a non-contact state, a voltage is applied while the photosensitive drum is rotated by a motor, and then, while the developing roller and the photosensitive drum are in a contact state, the rotation of the processing motor is used to determine whether there is toner solidification in the toner container.

[0007] To achieve the above objectives, the present invention provides an image forming apparatus, comprising: a photosensitive drum; a charge switch for energizing the photosensitive drum; a developing cartridge having a toner receiving portion for containing toner and a developing roller for supplying toner to the photosensitive drum; a contact separation mechanism for moving the developing roller between a contact position in contact with the photosensitive drum and a separation position separated from the photosensitive drum; a processing motor for rotating the photosensitive drum and the developing roller; and a drive transmission mechanism for transmitting a driving force from the processing motor to the developing roller, wherein when the developing roller is in the contact position, the drive transmission mechanism transmits the driving force from the processing motor to the developing roller, and ... When the developing roller is in the separated position, the drive transmission mechanism does not transmit the driving force from the processing motor to the developing roller; a high-voltage power supply board is used to apply a voltage to the charge carrier to charge the photosensitive drum; and a control unit performs the following toner consolidation determination process: while the developing roller is in the separated position, the photosensitive drum is rotated using the processing motor, and the voltage is applied to the charge carrier using the high-voltage power supply board. Then, while the developing roller is moved from the separated position to the contact position using the contact separation mechanism, the presence or absence of toner consolidation in the toner container is determined based on the rotation of the processing motor.

[0008] Therefore, when performing the toner consolidation judgment process, a potential difference is generated between the photosensitive drum and the developing roller in advance when the photosensitive drum and the developing roller are in a separated state. Thus, even if the photosensitive drum and the developing roller are in a contact state, it can prevent the toner from flowing from the developing roller into the photosensitive drum.

[0009] In the image forming apparatus of the present invention, when the developing roller is in the separated position, the control unit applies the voltage to the cable using the high-voltage power supply board, and after the processing motor has rotated at least a first predetermined number of rotations corresponding to at least one rotation of the photosensitive drum, the contact separation mechanism moves the developing roller from the separated position to the contact position.

[0010] Therefore, since a potential difference can be generated between the photosensitive drum and the developing roller on the entire surface of the photosensitive drum, the possibility of toner flowing from the developing roller into the photosensitive drum can be eliminated.

[0011] In the image forming apparatus of the present invention, when the control unit determines toner solidification based on the rotation of the processing motor while the developing roller is moved from the separation position to the contact position using the contact separation mechanism, if the number of rotations of the processing motor reaches a second predetermined number of rotations within a first predetermined time, the toner is not determined to be solidified; if the number of rotations of the processing motor does not reach a second predetermined number of rotations within the first predetermined time, the toner is determined to be solidified.

[0012] Therefore, by monitoring the number of rotations of the processing motor, the solidification of the toner can be determined.

[0013] The image forming apparatus of the present invention includes a processing motor that is a three-phase brushless motor, comprising a three-phase drive coil, a Hall element for detecting the rotational position of the rotor, and an FG sensor that generates an induced electromotive force as the rotor rotates. The image forming apparatus further includes a motor drive circuit for controlling the amount of current supplied to the three-phase drive coil based on a control signal input from a control unit, and switching the timing of the current supply to the three-phase drive coil. When the processing motor rotates, the control unit detects the number of rotations of the processing motor based on a Hall signal from the Hall element input via the motor drive circuit, and detects the rotational speed of the processing motor based on an FG signal from the FG sensor input via the motor drive circuit, and performs feedback control that changes the pulse width of the control signal output to the motor drive circuit according to the rotational speed.

[0014] Therefore, the control unit can precisely control the speed of the motor and other components, thereby optimizing the operating performance.

[0015] The image forming apparatus of the present invention further includes a non-volatile memory for storing a predetermined upper limit value of the pulse width of the control signal for each of the processing motors, such that as the current supplied to the drive coil of the processing motor increases, the rotation of the processing motor does not cause damage to the drive transmission mechanism. The control unit determines the manufacturer of the processing motor based on the signal from the processing motor, and when performing feedback control that changes the pulse width of the control signal output to the motor drive circuit according to the rotation speed, sets the upper limit value of the pulse width of the control signal to the upper limit value of the manufacturer stored in the non-volatile memory.

[0016] Therefore, the upper limit of the pulse width of the control signal is determined according to the value corresponding to the manufacturer of each processing motor, so that the processing motor is not over-rotated and damage to the drive transmission mechanism can be prevented.

[0017] The image forming apparatus of the present invention further includes: a fixing unit for thermally fixing a toner image formed by the photosensitive drum on a sheet, having a heating rotating body and a pressure rotating body, the heating rotating body having a heater, and the pressure rotating body pressing the sheet between the pressure rotating body and the heating rotating body; and a main motor for rotating the rotating body of the fixing unit, wherein the contact separation mechanism is capable of moving the developing roller between the contact position and the separation position by a driving force from the main motor.

[0018] Thus, the image forming apparatus can fix the toner image through the fixing device, and can move the developing roller with the same driving force.

[0019] In the image forming apparatus of the present invention, the toner is a positively charged toner with a positive polarity. When the developing roller is in the separated position, the control unit applies the voltage to the charge carrier using the high-voltage power supply board, thereby applying a positive first voltage to the charge carrier using the high-voltage power supply board to make the photosensitive drum have a higher voltage than that of the developing roller.

[0020] Therefore, by applying a positive voltage to the electrical charge, a potential difference is generated between the photosensitive drum and the developing roller, which prevents positively charged toner from flowing from the developing roller into the photosensitive drum even when the photosensitive drum and the developing roller are in contact.

[0021] In the image forming apparatus of the present invention, the toner is a positively charged toner with positive polarity. When the developing roller is in the separated position, the control unit applies the voltage to the charging device using the high-voltage power supply board, applies a positive second voltage to the charging device using the high-voltage power supply board, and applies a positive developing voltage to the developing roller. Through the voltage difference between the second voltage and the developing voltage, the photosensitive drum is made to be in a state with a higher voltage than that of the developing roller.

[0022] Therefore, by applying a positive voltage to the electrical charge and the developing roller, a potential difference is generated between the photosensitive drum and the developing roller, which can prevent positively charged toner from flowing from the developing roller into the photosensitive drum even when the photosensitive drum and the developing roller are in contact.

[0023] In the image forming apparatus of the present invention, the toner is a negatively charged toner with a negative polarity. When the developing roller is in the separated position, the control unit applies the voltage to the charging device using the high-voltage power supply board, and applies a negative third voltage to the charging device using the high-voltage power supply board, so that the photosensitive drum is in a state with a voltage lower than that of the developing roller.

[0024] Therefore, by applying a negative voltage to the charge, a potential difference is generated between the photosensitive drum and the developing roller, which prevents the negatively charged toner from flowing from the developing roller into the photosensitive drum even when the photosensitive drum and the developing roller are in contact.

[0025] The image forming apparatus of the present invention further includes a cover, which, when opened, allows the developing cartridge to be installed into and removed from the image forming apparatus. The control unit performs the toner consolidation judgment process when the image forming apparatus is first started or when the developing cartridge is detected to be replaced.

[0026] Therefore, even if the toner inside the image forming apparatus or developing cartridge solidifies due to temperature changes during transport or the effects of long-term storage, toner solidification can be determined before printing.

[0027] In the image forming apparatus of the present invention, the photosensitive drum is a plurality of photosensitive drums, and the developing cartridge is a plurality of developing cartridges respectively configured corresponding to the plurality of photosensitive drums. The control unit performs the toner solidification judgment process when one of the plurality of developing cartridges is installed, and determines whether the toner has solidified for the one developing cartridge.

[0028] Therefore, by judging the solidification of toner in a single developing cartridge, it is possible to determine whether toner has solidified in that developing cartridge.

[0029] The image forming apparatus of the present invention further includes a display unit. When the control unit performs the toner solidification determination process while one of the plurality of developing boxes is installed, if the toner solidification is not determined, the display unit displays the following instruction: remove the developing box; install a developing box different from the developing box.

[0030] Therefore, it is possible to determine the solidification of toner in each developing chamber sequentially, and to determine the solidification of each toner.

[0031] In the image forming apparatus of the present invention, each of the plurality of developing cartridges has a storage unit, and when the control unit performs the toner solidification determination process and determines that the toner has solidified while the developing cartridge is installed, it performs a toner solidification information storage process to store toner solidification information in the storage unit of the developing cartridge.

[0032] Therefore, by storing toner solidification information, the determination of toner solidification can be stored in the developing chamber where the toner has solidified.

[0033] In the image forming apparatus of the present invention, if a new developing cartridge is installed after the toner consolidation information storage processing and the storage unit of the newly installed developing cartridge does not store toner consolidation information, the control unit performs the toner consolidation determination processing; if the storage unit of the newly installed developing cartridge stores toner consolidation information, the control unit does not perform the toner consolidation determination processing.

[0034] Therefore, by determining toner solidification information, unwanted repetitive toner solidification detection processes can be eliminated. Furthermore, the processing of the developing rollers in the developing cartridge that have experienced toner solidification can be reduced.

[0035] The image forming apparatus of the present invention further includes: a cover; and a display unit, wherein the photosensitive drum is a plurality of photosensitive drums, and the developing cartridges are a plurality of developing cartridges respectively configured corresponding to the plurality of photosensitive drums and respectively capable of being installed into and removed from the image forming apparatus when the cover is opened. When the control unit performs the toner solidification determination process with all of the plurality of developing cartridges installed and determines that the toner is solidified, it displays an indication on the display unit that only the developing cartridge containing black toner is installed. Then, when only the developing cartridge containing black toner is installed, it performs the toner solidification determination process. If the toner is not determined to be solidified, it displays on the display unit that monochrome printing is possible; if the toner is determined to be solidified, it displays an error message that printing is not possible.

[0036] Therefore, even if toner solidifies in a developing cartridge other than the one containing black toner, monochrome printing can still be performed using the developing cartridge containing black toner, allowing users to print before replacing the developing cartridge.

[0037] In the image forming apparatus of the present invention, the control unit performs the following fault judgment process: when the developing roller is in the separation position, the processing motor is rotated, and it is determined whether the rotation speed of the processing motor has reached the target speed within a second predetermined time. If the target speed is not reached within the second predetermined time, it is determined that the processing motor has malfunctioned. The toner solidification judgment process is performed after the fault judgment process is executed, if it is not determined that the processing motor has malfunctioned.

[0038] Therefore, since the determination of toner solidification is performed after confirming that the processing motor has not malfunctioned, it is possible to prevent the toner solidification from being mistakenly detected due to a malfunction in the processing motor.

[0039] The image forming apparatus of the present invention, by generating a potential difference between the photosensitive drum and the developing roller, can determine the solidification of toner even when the photosensitive drum and the developing roller are in contact, provided that the toner does not flow from the developing roller into the photosensitive drum. Attached Figure Description

[0040] Figure 1 This is a schematic structural diagram of the image forming apparatus according to this embodiment.

[0041] Figure 2 This is a block diagram illustrating the structure of the image forming apparatus of this embodiment.

[0042] Figure 3 This is a schematic structural diagram of the drive transmission mechanism in this embodiment.

[0043] Figure 4 This is a schematic structural diagram of the processing motor in this embodiment.

[0044] Figure 5 This is a diagram illustrating the high-voltage substrate used in the toner solidification judgment process.

[0045] Figure 6 It is a graph showing the relationship between charge and toner movement.

[0046] Figure 7 This is a flowchart for judging and processing the solidification of toner.

[0047] Figure 8 This is a flowchart for troubleshooting motor malfunctions.

[0048] Figure 9 This is a flowchart of the process for changing toner.

[0049] Figure 10 This is a flowchart for determining the pattern of consolidation color.

[0050] Figure 11 This is a flowchart for determining whether monochrome printing is possible. Detailed Implementation

[0051] Hereinafter, a specific embodiment of the image forming apparatus of the present invention will be described in detail with reference to the accompanying drawings. First, Figure 1 This is a schematic structural diagram of the image forming apparatus according to this embodiment.

[0052] like Figure 1 As shown, the image forming apparatus 1 is a color printer, including a housing 10, a display unit 14, a front cover 11, a sheet supply unit 20, an image forming unit 30, and a second discharge roller 84 serving as a discharge roller. In this embodiment, Figure 1 Set the left side to "front" and... Figure 1 The right side is set to "after". Additionally, [the following text is incomplete and likely refers to a different topic:] ... Figure 1 The top side is set to "top". Figure 1 The bottom side is set to "bottom". Additionally, [the following text is incomplete and likely refers to a different topic:] ... Figure 1 The front side of the paper is designated as "right". Figure 1 The paper depth side is set to "left".

[0053] The housing 10 has an opening 10A at the front. The front cover 11 opens and closes the opening 10A. Specifically, the front cover 11 is rotatable relative to the housing 10 between a closed position (shown by solid lines) and an open position (shown by dashed lines). The closed position is the position where the opening 10A is closed, and the open position is the position where the opening 10A is open.

[0054] Display unit 14 is a liquid crystal display, mounted on housing 10, which displays various information to the user based on image signals obtained from ASIC 92.

[0055] The sheet supply unit 20 includes a sheet tray 21 and a sheet supply mechanism 22. Sheets S are placed on the sheet tray 21. The sheet supply mechanism 22 is a mechanism that supplies the sheet S to the photosensitive drums 50 (50Y, 50M, 50C, 50K) of the image forming unit 30 by receiving a driving force. The sheet supply mechanism 22 includes a pickup roller 23, a separation roller 24, a separation pad 25, a transport roller 26, and a positioning roller 27.

[0056] The sheet supply mechanism 22 feeds sheet S from sheet tray 21 via pick-up roller 23. Next, the sheet supply mechanism 22 separates sheet S into individual sheets between separation roller 24 and separation pad 25. Afterward, the sheet supply mechanism 22 supplies sheet S to image forming unit 30 via conveying roller 26 and positioning roller 27.

[0057] The image forming unit 30 includes an exposure unit 40, four photosensitive drums 50, four developing cartridges 60, a transfer unit 70, and a fixing unit 80. The exposure unit 40 includes, for example, a light source, a deflector, a lens, and a mirror. The exposure unit 40 emits a light beam (shown as a dashed line) to expose the surface of the photosensitive drums 50.

[0058] The photosensitive drum 50 includes a photosensitive drum 50Y corresponding to yellow, a photosensitive drum 50M corresponding to magenta, a photosensitive drum 50C corresponding to cyan, and a photosensitive drum 50K corresponding to black. The four photosensitive drums 50 are arranged from upstream to downstream in the conveying direction of the sheet S in the order of photosensitive drum 50Y, photosensitive drum 50M, photosensitive drum 50C, and photosensitive drum 50K.

[0059] Specifically, photosensitive drum 50Y is positioned upstream of photosensitive drum 50M in the conveying direction of sheet S. Photosensitive drum 50M is positioned upstream of photosensitive drum 50C in the conveying direction of sheet S. Photosensitive drum 50C is positioned upstream of photosensitive drum 50K in the conveying direction of sheet S.

[0060] In this specification and the accompanying drawings, for components corresponding to each color, Y, M, C, and K are added after the reference numerals when the color is distinguished; otherwise, Y, M, C, and K are not added after the reference numerals.

[0061] The image forming apparatus 1 also includes a drawer 55. The drawer 55 is exposed by opening the front cover 11 and can move between an inner position and an outer position along the direction in which the photosensitive drums 50 are arranged, through an opening 10A in the housing 10. The inner position is the position where the drawer 55 is housed within the housing 10, and the outer position is the position where at least a portion of the drawer 55 protrudes outside the housing 10. In this embodiment, the outer position is the position where the drawer 55 is pulled forward from the inner position. Furthermore, in this embodiment, the drawer 55 is detachable relative to the housing 10.

[0062] Drawer 55 has a frame 55F. The frame 55F rotatably supports four photosensitive drums 50 (50Y, 50M, 50C, 50K). In addition, the frame 55F supports four electrical conductors 52. The electrical conductors 52 charge the surfaces of the corresponding photosensitive drums 50.

[0063] The developing cartridge 60 has a toner container 63 for containing toner, including: a developing cartridge 60Y having a toner container 63Y for containing yellow toner, a developing cartridge 60M having a toner container 63M for containing magenta toner, a developing cartridge 60C having a toner container 63C for containing cyan toner, and a developing cartridge 60K having a toner container 63K for containing black toner. The developing cartridge 60Y has a developing roller 61Y for supplying yellow toner to the photosensitive drum 50Y. The developing cartridge 60M has a developing roller 61M for supplying magenta toner to the photosensitive drum 50M. The developing cartridge 60C has a developing roller 61C for supplying cyan toner to the photosensitive drum 50C. The developing cartridge 60K has a developing roller 61K for supplying black toner to the photosensitive drum 50K.

[0064] The developing roller 61Y is movable relative to the photosensitive drum 50Y between a contact position that contacts the photosensitive drum 50Y and a separation position that separates from the photosensitive drum 50Y. The developing roller 61M is movable relative to the photosensitive drum 50M between a contact position that contacts the photosensitive drum 50M and a separation position that separates from the photosensitive drum 50M. The developing roller 61C is movable relative to the photosensitive drum 50C between a contact position that contacts the photosensitive drum 50C and a separation position that separates from the photosensitive drum 50C. The developing roller 61K is movable relative to the photosensitive drum 50K between a contact position that contacts the photosensitive drum 50K and a separation position that separates from the photosensitive drum 50K.

[0065] The frame 55F of drawer 55 supports the developing cartridges 60 (60Y, 60M, 60C, 60K) in a removable manner. Each developing cartridge 60 can be replaced with drawer 55 in the outward position or with drawer 55 removed from housing 10.

[0066] The developing cartridge 60 is supported on the frame 55F, allowing it to move back and forth between a first position indicated by a solid line and a second position indicated by a dashed line. The first position is where the corresponding developing roller 61 is in the contact position, and the second position is where the corresponding developing roller 61 is in the separation position.

[0067] Specifically, the developing cartridge 60Y is movable relative to the photosensitive drum 50Y between a first position and a second position, in which the developing roller 61Y is in a contact position and in the second position, the developing roller 61Y is in a separated position. In other words, the developing cartridge 60Y is movable relative to the photosensitive drum 50Y between a first position where the developing roller 61Y is in contact with the photosensitive drum 50Y and a second position where the developing roller 61Y is separated from the photosensitive drum 50Y.

[0068] Furthermore, the developing cartridge 60M is movable relative to the photosensitive drum 50M between a first position and a second position, in which the developing roller 61M is in a contact position and in the second position, the developing roller 61M is in a separated position. In other words, the developing cartridge 60M is movable relative to the photosensitive drum 50M between a first position where the developing roller 61M is in contact with the photosensitive drum 50M and a second position where the developing roller 61M is separated from the photosensitive drum 50M.

[0069] Furthermore, the developing cartridge 60C is movable relative to the photosensitive drum 50C between a first position and a second position, in which the developing roller 61C is in a contact position and in the second position, the developing roller 61C is in a separated position. In other words, the developing cartridge 60C is movable relative to the photosensitive drum 50C between a first position where the developing roller 61C is in contact with the photosensitive drum 50C and a second position where the developing roller 61C is separated from the photosensitive drum 50C.

[0070] Furthermore, the developing cartridge 60K is movable relative to the photosensitive drum 50K between a first position and a second position, in which the developing roller 61K is in a contact position and in the second position, the developing roller 61K is in a separated position. In other words, the developing cartridge 60K is movable relative to the photosensitive drum 50K between a first position where the developing roller 61K contacts the photosensitive drum 50K and a second position where the developing roller 61K is separated from the photosensitive drum 50K.

[0071] In addition, each developer cartridge 60 includes a toner IC 62. The toner IC 62 is a non-volatile storage unit capable of rewriting data, storing toner solidification information and identification information of the developer cartridge 60, etc. The toner IC 62 is an example of a storage unit.

[0072] The transfer unit 70 includes a drive roller 71, a driven roller 72, an annular conveyor belt 73, and four transfer rollers 74. When the conveyor belt 73 is mounted on the drive roller 71 and the driven roller 72, its outer surface contacts the four photosensitive drums 50. The transfer rollers 74 are positioned inside the conveyor belt 73, sandwiching the conveyor belt 73 between themselves and their corresponding photosensitive drums 50.

[0073] The fuser 80 is an example of a fixing device, which is a means of thermally fixing a toner image transferred onto a sheet S onto the sheet S. The fuser 80 includes a heating section 81, a pressure section 82, and a first discharge roller 83 as a discharge roller. The heating section 81 is an example of a heated rotating body, including a heating roller 81A and a heater 81B. The heating roller 81A is a cylindrical roller made of metal. The heater 81B is a heater for heating the heating roller 81A and is configured to pass through the inside of the heating roller 81A.

[0074] The pressure section 82 is an example of a pressure rotating body that presses the sheet S between itself and the heating section 81. Specifically, the pressure section 82 is a pressure roller that holds the sheet S between itself and the heating roller 81A. The pressure roller is a roller with a rubber layer covering the area around a metal core. The fuser 80 receives a driving force, thereby conveying the sheet S between the heating roller 81A of the heating section 81 and the pressure section 82 (pressure roller). Furthermore, the fuser 80 receives a driving force, thereby conveying the sheet S through the first discharge roller 83.

[0075] After the image forming unit 30 uniformly charges the surface of the photosensitive drum 50 with the charge carrier 52, it exposes it to a light beam irradiated from the exposure unit 40. Thus, the image forming unit 30 forms an electrostatic latent image based on image data on the photosensitive drum 50. Additionally, the image forming unit 30 supplies toner contained in the developing cartridge 60 to the photosensitive drum 50 from the developing roller 61 located at the contact position. Thus, the image forming unit 30 forms a toner image on the photosensitive drum 50.

[0076] The image forming unit 30 transfers the toner image formed on the photosensitive drum 50 onto the sheet S supplied from the sheet supply unit 20 by conveying the sheet S between the photosensitive drum 50 and the transfer roller 74. Then, the image forming unit 30 conveys the sheet S with the transferred toner image between the heating roller 81A and the pressure unit 82, thereby fixing the toner image onto the sheet S.

[0077] The first discharge roller 83 and the second discharge roller 84 receive driving force, thereby discharging the sheet S from between the heating section 81 and the pressurizing section 82 to the outside of the housing 10. Specifically, the first discharge roller 83 and the second discharge roller 84 discharge the sheet S with the toner image fixed onto the discharge tray 13.

[0078] Figure 2This is a block diagram showing the structure of the image forming apparatus of this embodiment. The main substrate 91 is connected to the main motor M1, the processing motor M2, the high-voltage power supply substrate 51, and the display unit 14.

[0079] First, the main board 91 is a control board for overall control of the image forming apparatus, including: an ASIC 92, a RAM 93 used as working memory when the ASIC 92 performs various arithmetic operations, an NVRAM 94 storing control programs, a main motor drive circuit 101, and a processing motor drive circuit 102. The ASIC 92 is an example of a control unit.

[0080] The main motor drive circuit 101 is connected to the ASIC 92 and the main motor M1. The main motor drive circuit 101 controls the rotational speed and direction of the main motor M1 based on instructions from the ASIC 92.

[0081] The processing motor drive circuit 102 is connected to the ASIC 92 and the processing motor M2. The processing motor drive circuit 102 controls the rotational speed and direction of the processing motor M2 based on instructions from the ASIC 92. This will be explained in detail later.

[0082] The high-voltage power supply board 51 applies a voltage to the charge carrier 52 to energize the photosensitive drum. Additionally, the high-voltage power supply board 51 can also apply voltage to the developing roller 61.

[0083] The main motor M1 is connected to transmit driving force to the developing separation gear system GT1, the fixing drive gear system GT2, the clamping pressure adjustment gear system GT3, and the sheet supply gear system GT4. Additionally, the main motor M1 drives the separation cam of the contact separation mechanism 5, the fuser 80, the clamping pressure adjustment mechanism 200, and the sheet supply mechanism 22 via these gear systems. The main motor M1 can rotate in both directions; it rotates forward to form an image on the sheet S when conveying the sheet S from the sheet tray 21 to the discharge tray 13.

[0084] The processing motor M2 is connected to transmit driving force to the drum drive gear train GT5 and the developing drive gear train GT6. In addition, the processing motor M2 drives the photosensitive drum 50, the developing roller 61 and the transfer unit 70 through the respective gear trains.

[0085] The developer separation gear system GT1 is a gear system that transmits the driving force of the main motor M1 to the separation cam 150 of the contact separation mechanism 5. Furthermore, the developer separation gear system GT1 includes an electromagnetic clutch EC1 and an electromagnetic clutch EC2. Electromagnetic clutch EC1 is located between the main motor and separation cams 150Y, 150M, and 150C. Electromagnetic clutch EC2 is located between the main motor and separation cam 150K.

[0086] The fixing drive gear system GT2 receives the driving force of the main motor M1 from the developing separation gear system GT1 and transmits it to the gear system of the fuser 80. More specifically, the fixing drive gear system GT2 receives the driving force of the main motor M1 from the developing separation gear system GT1 and transmits the driving force to the heating roller 81A.

[0087] The clamping pressure adjusting gear train GT3 receives the driving force of the main motor from the developing separation gear train GT1 and transmits it to the clamping pressure adjusting mechanism 200. The sheet feeding gear train GT4 transmits the driving force of the main motor M1 to the sheet feeding mechanism 22. The drum drive gear train GT5 transmits the driving force of the processing motor M2 to the photosensitive drum 50 and the drive roller 71.

[0088] The developing drive gear system GT6 is the drive transmission mechanism that transmits the driving force of the processing motor M2 to the developing roller 61. This will be explained in detail later.

[0089] The electromagnetic clutch EC1 can switch between a transmitting state and a disengaged state. As an example, the electromagnetic clutch EC1 is in the transmitting state when energized and in the disengaged state when de-energized. The transmitting state is when the driving force of the autonomous motor M1 is transmitted to the release cams 150Y, 150M, and 150C. The disengaged state is when the driving force of the autonomous motor M1 is not transmitted to the release cams 150Y, 150M, and 150C. The electromagnetic clutch EC1 is controlled by an ASIC 92.

[0090] The electromagnetic clutch EC2 can switch between a transmitting state and a disengaged state. As an example, the electromagnetic clutch EC2 is in the transmitting state when energized and in the disengaged state when de-energized. The transmitting state is when the driving force of the future autonomous motor M1 is transmitted to the release cam 150K. The disengaged state is when the driving force of the future autonomous motor M1 is not transmitted to the release cam 150K. The electromagnetic clutch EC2 is controlled by ASIC 92.

[0091] The contact separation mechanism 5 is a mechanism that moves the developing roller 61 between a contact position and a separation position by receiving driving force from the main motor M1. The contact separation mechanism 5 includes four separation cams 150 and a structure that moves the developing roller 61 by rotating the separation cams 150. The separation cams 150 include separation cam 150Y, separation cam 150M, separation cam 150C, and separation cam 150K.

[0092] The separation cam 150Y rotates by receiving driving force from the main motor M1, causing the developing roller 61Y to move between a contact position and a separation position. Specifically, the separation cam 150Y rotates to move the developing cartridge 60Y between a first position and a second position, thereby moving the developing roller 61Y between the contact position and the separation position. The separation cam 150M rotates by receiving driving force from the main motor M1, causing the developing roller 61M to move between the contact position and the separation position. More specifically, the separation cam 150M rotates to move the developing cartridge 60M between a first position and a second position, thereby moving the developing cartridge 60M between the contact position and the separation position.

[0093] Separation cam 150C rotates by receiving driving force from main motor M1, causing developing roller 61C to move between a contact position and a separation position. More specifically, separation cam 150C rotates to move developing cartridge 60C between a first position and a second position, thereby moving developing cartridge 60C between the contact position and the separation position. Separation cam 150K rotates by receiving driving force from main motor M1, causing developing roller 61K to move between a contact position and a separation position. More specifically, separation cam 150K rotates to move developing cartridge 60K between a first position and a second position, thereby moving developing cartridge 60K between the contact position and the separation position.

[0094] The clamping pressure adjustment mechanism 200 switches between a first clamping pressure and a second clamping pressure, which is generated by the heating part 81 and the pressurizing part 82 of the fuser 80.

[0095] Figure 3 This is a diagram showing the separation cam 150 and the gear train, which is part of the developing drive gear train GT6 as a drive transmission mechanism. Figure 3 This refers to the gear system viewed from right to left in the image forming apparatus 1. First, the separation cam 150Y (cam gear 115Y), separation cam 150M (cam gear 115M), separation cam 150C (cam gear 115C), separation cam 150K (cam gear 115K), idler gear 118, and gear 116 are part of the developing separation gear system GT1.

[0096] Separating cam 150C (cam gear 115C) meshes with separating cam 150M (cam gear 115M) via gear 116, and separating cam 150M (cam gear 115M) meshes with separating cam 150Y (cam gear 115Y) via idler gear 118. Furthermore, separating cam 150C (cam gear 115C) can transmit the driving force of the main motor M1 to developing cartridges 60Y, 60M, and 60C via electromagnetic clutch EC1. Thus, when electromagnetic clutch EC1 is in the transmission state, separating cams 150Y (cam gear 115Y), 150M (cam gear 115M), and 150C (cam gear 115C) move developing cartridges 60Y, 60M, and 60C between a contact position and a separating position in a coordinated manner. When the main motor M1 rotates forward, it moves from the separating position to the contact position; when the main motor M1 rotates in reverse, it moves from the contact position to the separating position. In addition, when the electromagnetic clutch EC1 is in the disengaged state, the contact position or the disengaged position is maintained.

[0097] The separation cam 150K (cam gear 115K) transmits the driving force of the main motor M1 to the developing cartridge 60K via the electromagnetic clutch EC2. Thus, when the electromagnetic clutch EC2 is in the transmission state, the separation cam 150K (cam gear 115K) moves the developing cartridge 60K between a contact position and a separation position. When the main motor M1 rotates forward, it moves from the separation position to the contact position; when the main motor M1 rotates in reverse, it moves from the contact position to the separation position. Furthermore, when the electromagnetic clutch EC2 is disengaged, either the contact or separation position is maintained.

[0098] According to the aforementioned developing and separating gear system GT1, the driving force of the main motor M1 can be controlled to be in a transmission state and a cut-off state via electromagnetic clutches EC1 and EC2. In the transmission state, the developing rollers 61 (61Y, 61M, 61C, 61K) are moved to a contact position or a separation position that is in contact with or separated from the photosensitive drum 50 (50Y, 50M, 50C, 50K) via the contact separation mechanism 5. Furthermore, by setting only the electromagnetic clutch EC1 to the cut-off state, only the developing roller 61K can be moved to the contact position or the separation position that is in contact with or separated from the photosensitive drum 50K.

[0099] The developing drive gear system GT6 consists of gears 421, 422, 423, a moving gear 424, a first output gear 425, a connecting gear 426Y, a connecting gear 426M, a gear 427, a connecting gear 426C, gears 431, 432, 433, 434, 435, a first gear 436, a planetary gear mechanism 180, a connecting gear 426K as a second gear, and a switching cam.

[0100] Gear 421 is a two-stage gear with a major diameter gear and a minor diameter gear, the major diameter gear meshing with motor gear MG2. In the front-rear direction, motor gear MG2 is located between the rotation center of connecting gear 426M and the rotation center of connecting gear 426C.

[0101] Gear 422 meshes with the minor diameter gear of gear 421.

[0102] Gear 423 meshes with gear 422.

[0103] The movable gear 424 is a gear that receives driving force from the processing motor M2 and meshes with gear 423. The movable gear 424 is movable relative to the first output gear 425 between a first transmission position (shown by a solid line) and a first cut-off position (shown by a dashed line). Specifically, the movable gear 424 is supported so that it can oscillate about gear 423 between the first transmission position and the first cut-off position.

[0104] The first transmission position is the position where it engages with the first output gear 425, outputting the driving force of the processing motor M2 to the developing rollers 61Y, 61M, and 61C. The first cut-off position is the position where it does not engage with the first output gear 425, and does not output the driving force of the processing motor M2 to the developing rollers 61Y, 61M, and 61C. The moving gear 424 is spring-loaded from the first cut-off position to the first transmission position. The moving gear 424 moves between the first transmission position and the first cut-off position via a switching cam (not shown).

[0105] The first output gear 425 is a gear that outputs driving force to the developing rollers 61Y, 61M, and 61C. The first output gear 425 is a two-stage gear with a large-diameter gear and a small-diameter gear, and the large-diameter gear meshes with the moving gear 424 located at the first transmission position.

[0106] The connecting gear 426Y meshes with the minor diameter gear of the first output gear 425. The connecting gear 426Y is the gear that outputs the driving force from the processing motor M2 to the developing roller 61Y. Specifically, the connecting gear 426Y outputs the driving force from the processing motor M2 to the developing cartridge 60Y.

[0107] The connecting gear 426M meshes with the minor-diameter gear of the first output gear 425. The connecting gear 426M is the gear that outputs the driving force from the processing motor M2 to the developing roller 61M. More specifically, the connecting gear 426M outputs the driving force from the processing motor M2 to the developing cartridge 60M.

[0108] Gear 427 meshes with connecting gear 426M.

[0109] The connecting gear 426C meshes with gear 427. The connecting gear 426C is the gear that outputs the driving force from the processing motor M2 to the developing roller 61C. More specifically, the connecting gear 426C outputs the driving force from the processing motor M2 to the developing cartridge 60C.

[0110] In addition, gear 431 meshes with gear 422.

[0111] Gear 432 meshes with gear 431.

[0112] Gear 433 meshes with gear 432.

[0113] Gear 434 meshes with gear 433. Gear 434 rotates coaxially with connecting gear 426C.

[0114] Gear 435 meshes with gear 434.

[0115] The first gear 436 receives driving force from the processing motor M2 and meshes with gear 435. The first gear 436 meshes with the planetary gear mechanism 180. The first gear 436 rotates coaxially with the connecting gear 426K.

[0116] The planetary gear mechanism 180 meshes with the connecting gear 426K. When the internal gear stops rotating, the driving force of the processing motor M2 is output to the developing roller 61K via the first gear 436. On the other hand, when the internal gear continues to rotate, the driving force of the processing motor M2 transmitted by the first gear 436 does not cause the connecting gear 426K to rotate, and no driving force is output to the developing roller 61K.

[0117] The separating cam 150K (cam gear 115K) corresponding to the black color has a protrusion 154 extending from its outer peripheral surface. Furthermore, the protrusion 154 can contact the switching lever 160. The protrusion 154 contacts the arm 160A of the switching lever 160 in response to the rotation of the separating cam 150K, thereby enabling the switching lever 160 to rotate. In addition to the arm 160A that contacts the protrusion 154, the switching lever 160 also has an arm 160B that contacts the internal gear of the planetary gear mechanism 180. The contact between arm 160B and the internal gear of the planetary gear mechanism 180 prevents the internal gear from rotating. Conversely, the absence of contact between arm 160B and the internal gear of the planetary gear mechanism 180 allows the internal gear to rotate.

[0118] Furthermore, when the separation cam 150K (cam gear 115K) rotates in response to the rotation of the main motor M1 to move the developing cartridge 60K from the contact position to the separation position, the separation cam 150K (cam gear 115K) contacts the arm 160A of the switching lever 160 via the protrusion 154. That is, in conjunction with the contact separation mechanism 5 moving the developing cartridge 60K from the contact position to the separation position via the driving force of the main motor M1, the switching lever 160 does not contact the internal gear of the planetary gear mechanism 180, the driving force of the processing motor M2 does not cause the connecting gear 426K to rotate, and no driving force is output to the developing roller 61K.

[0119] The switching cam (not shown) is a plate-shaped cam that rotates by receiving driving force from the main motor M1. The structure that uses a switching cam to transfer gears between contact and non-contact states is known technology and therefore will not be described in detail. The switching cam rotates by receiving driving force from the main motor M1 from the cam gear 115M, causing the moving gear 424 of the developing drive gear train GT6 to move relative to the first output gear 425 between a first transmission position shown in solid lines and a first cut-off position shown in dashed lines. When the main motor M1 rotates forward, the switching cam moves the moving gear 424 from the first cut-off position to the first transmission position. Furthermore, when the main motor M1 rotates in reverse, the switching cam moves the moving gear 424 from the first transmission position to the first cut-off position.

[0120] According to the developing drive gear system GT6 described above as the drive transmission mechanism, when the developing rollers 61 (61Y, 61M, 61C, 61K) are in a position separated from the photosensitive drum 50 (50Y, 50M, 50C, 50K) by the developing separation gear system GT1, the driving force from the processing motor M2 is not transmitted to the developing rollers 61 (61Y, 61M, 61C, 61K). On the other hand, when they are in a contact position, the driving force from the processing motor M2 is transmitted to the developing rollers 61 (61Y, 61M, 61C, 61K). Furthermore, by setting only the electromagnetic clutch EC1 to the disengaged state, when only the developing roller 61K is in contact with the photosensitive drum 50K, the driving force from the processing motor M2 is transmitted only to the developing roller 61K.

[0121] like Figure 4 As shown, the processing motor M2 is a three-phase brushless motor with three-phase (U, V, W) drive coils M2C on the stator, Hall elements M2U, M2V, and M2W for detecting the rotational position of the rotor, and an FG (Frequency Generator) sensor M2S.

[0122] The FG sensor M2S is configured to generate an induced electromotive force as the rotor of the brushless motor rotates. The FG sensor M2S outputs an AC signal (FG signal) at a frequency corresponding to the rotor's rotational speed. The FG signal has a high frequency when the brushless motor rotates at high speeds and a low frequency when the rotational speed is slow.

[0123] ASIC 92 detects the rotational speed of the three-phase brushless motor based on the FG signal input via the motor drive circuit 102. ASIC 92 performs feedback control based on the FG signal output from the FG sensor M2S, changing the pulse width (duty cycle) of the PWM signal used as a control signal and outputting it to the motor drive circuit. The motor drive circuit 102 controls the amount of current supplied to the three-phase drive coil M2C according to the duty cycle of the input PWM signal, and switches the direction of the magnetic field generated by the three-phase drive coil M2C by switching the timing of the current supply to the three-phase drive coil M2C based on the Hall signals input from Hall elements M2U, M2V, and M2W, thereby causing the rotor to rotate.

[0124] In addition, the main motor M1 is also a three-phase brushless motor, controlled by an ASIC 92 through the same structure. Furthermore, the motor drive circuit is as follows... Figure 2 As shown, the main motor drive circuit 101 is used.

[0125] according to Figure 5 To explain the charging of each part during the toner solidification determination process in the image forming apparatus 1 equipped with the above structure, the high-voltage power supply board 51 is configured to apply voltage to the charger 52 and the developing roller 61. Furthermore, the high-voltage power supply board 51 can apply voltage to the developing roller 61 in either the separated position or the contact position.

[0126] At the separation position, the high-voltage power supply board 51 applies a positive first voltage to the belt conveyor 52. Furthermore, the ASIC 92 rotates the processing motor M2, thereby rotating the photosensitive drum 50 and the drive roller 71 via the drum drive gear train GT5. The belt conveyor 52 positively charges the surface of the photosensitive drum 50 based on the positive first voltage applied from the high-voltage power supply board 51. Additionally, the rotation of the photosensitive drum 50 uniformly charges its entire surface with positive charge. The toner contained in the developing cartridge 60 is a positively charged toner, and the surface of the photosensitive drum 50 is at a higher voltage than the developing roller 61.

[0127] When energizing the photosensitive drum 50, it is rotated at least one revolution. When the number of revolutions of the processing motor M2 reaches or exceeds the predetermined number of revolutions required to rotate the photosensitive drum 50 at least one revolution, the ASIC 92 moves the developing roller 61 from the separation position to the contact position. This allows the photosensitive drum 50 to be energized at a predetermined number of revolutions, regardless of its torque, ensuring uniform and complete energization across the entire surface. Furthermore, the predetermined number of revolutions of the processing motor M2 required to rotate the photosensitive drum 50 at least one revolution can also be pre-stored in the NVRAM 94 based on the gear ratio of the drum drive gear system GT5, etc.

[0128] Therefore, as Figure 6 As shown, when the developing roller 61 is moved from the separation position to the contact position, the positively charged toner that has moved to the surface of the developing roller 61 will not move from the developing roller 61 to the photosensitive drum 50, and the positively charged toner will not move to the surface of the photosensitive drum 50 due to the potential difference. On the other hand, if the entire surface of the photosensitive drum 50 is not uniformly positively charged, the toner will undesirably move to the photosensitive drum 50.

[0129] In addition to applying voltage to the belt conveyor 52, the high-voltage power supply board 51 can also apply a developing voltage to the developing roller 61. A positive second voltage is applied to the belt conveyor 52, and when the developing roller 61 is in the separated position, the high-voltage power supply board 51 applies different positive voltages to the developing roller 61 and the belt conveyor 52. The voltage is one that makes the surface of the photosensitive drum 50 have a higher voltage than that of the developing roller 61.

[0130] Therefore, when the developing roller 61 is moved from the separation position to the contact position, the positively charged toner that has moved to the surface of the developing roller 61 will not move from the developing roller 61 to the photosensitive drum 50, and the positively charged toner will not move to the surface of the photosensitive drum 50 due to the potential difference.

[0131] Additionally, a negative third voltage can be applied to the high-voltage power supply board 51. In the separated position, the high-voltage power supply board 51 applies a negative third voltage to the belt conveyor 52. The ASIC 92 rotates the processing motor M2, thereby rotating the photosensitive drum 50 and the drive roller 71 via the drum drive gear train GT5. The belt conveyor 52 negatively charges the surface of the photosensitive drum 50 based on the negative third voltage applied from the high-voltage power supply board 51. Furthermore, the rotation of the photosensitive drum 50 uniformly negatively charges its entire surface. The toner contained in the developing cartridge 60 is a negatively charged toner, and the surface of the photosensitive drum 50 is at a voltage lower than that of the surface of the developing roller 61.

[0132] Therefore, when the developing roller 61 is moved from the separation position to the contact position, the negatively charged toner that has moved to the surface of the developing roller 61 will not move from the developing roller 61 to the photosensitive drum 50, and the negatively charged toner will not move to the surface of the photosensitive drum 50 due to the potential difference.

[0133] Next, based on Figure 7 The process for determining toner solidification is explained below. First, the steps will be referred to as S. In S1, the ASIC 92 determines the manufacturer of the processing motor M2. Specifically, the manufacturer of the processing motor M2 is determined based on the characteristics of the FG signal and Hall signal input to the ASIC 92 from the Hall element M2U, Hall element M2V, Hall element M2W, and FG sensor M2S via the processing motor drive circuit 102. Alternatively, the manufacturer can also be determined by reading the determination terminal provided on the processing motor M2.

[0134] In S2, ASIC 92 sets the upper limit value of the pulse width for processing motor M2. The upper limit value of the pulse width, pre-determined for each manufacturer, is stored in NVRAM 94. Based on the manufacturers of the processing motor M2 determined in S1, ASIC 92 sets the upper limit value of the pulse width stored in NVRAM 94 as the upper limit value of the pulse width for processing motor M2.

[0135] The upper limit of the pulse width is the upper limit at which the developing drive gear system GT6, as the drive transmission mechanism, will not be damaged due to the rotation of the processing motor M2 when the ASIC 92 outputs a control signal to increase the current supplied to the three phases of the drive coil of the processing motor M2.

[0136] In S3, the ASIC 92 drives the processing motor M2. Additionally, the high-voltage power supply board 51 applies a voltage to the capacitor 52, which, based on the positive voltage applied from the high-voltage power supply board 51, positively charges the surface of the photosensitive drum 50. For example... Figure 5 As shown, the developing roller 61 is in the separation position.

[0137] In step S4, ASIC 92 determines whether the rotation number of the processing motor M2 has reached a first predetermined number of rotations required to rotate the photosensitive drum 50 more than one revolution. ASIC 92 repeatedly performs this determination until the rotation number of the processing motor M2 reaches the first predetermined number of rotations required to rotate the photosensitive drum 50 more than one revolution. If the first predetermined number of rotations has been reached, the process proceeds to step S5. Furthermore, as described above, the photosensitive drum 50 is energized at the predetermined number of rotations to ensure that the entire surface is uniformly and completely energized.

[0138] In step S5, ASIC 92 moves the developing roller 61 from the separation position to the contact position. Specifically, ASIC 92 starts driving the main motor M1. Then, electromagnetic clutches EC1 and EC2 are energized to switch from the cut-off state to the transmission state, and the driving force of the main motor M1 is transmitted to the developing separation gear train GT1. As a result, the contact separation mechanism 5 moves the developing roller 61 from the separation position to the contact position by the driving force of the main motor M1. In addition, while moving to the contact position, the developing drive gear train GT6, as a drive transmission mechanism, moves the moving gear 424 from the first cut-off position to the first transmission position. In addition, the switching lever 160 stops the rotation of the internal gear of the planetary gear mechanism 180. After a certain period of time, ASIC 92 stops energizing electromagnetic clutches EC1 and EC2, thereby switching from the transmission state to the cut-off state and stopping the drive of the main motor M1.

[0139] In S6, ASIC 92 measures the number of rotations of the processing motor M2 based on the Hall signals input from Hall elements M2U, M2V, and M2W, and then determines whether the processing motor M2 has rotated more than a second predetermined number of times. If the processing motor M2 has not rotated more than the second predetermined number of times, proceed to S7; if the processing motor M2 has rotated more than the second predetermined number of times, proceed to S9.

[0140] In S7, ASIC 92 determines whether the elapsed time since the start of driving the processing motor M2 has exceeded a first predetermined time. Here, the first predetermined time is the time required for the processing motor M2 to rotate to a second predetermined number of revolutions before the toner in the developing cartridge 60 has solidified; it is also the time that the processing motor M2 cannot rotate to the second predetermined number of revolutions before the toner in the developing cartridge 60 has solidified. For example, different first predetermined time and second predetermined number of revolutions can be set for each manufacturer of the processing motor M2 determined in S1. If the elapsed time since the start of driving the processing motor M2 has exceeded the first predetermined time, proceed to S8; if the elapsed time since the start of driving the processing motor M2 has not exceeded the first predetermined time, proceed to S6.

[0141] In S8, ASIC 92 determines that the toner in the developing cartridge 60 has solidified. That is, it determines that the processing motor M2 cannot rotate at the second predetermined number of revolutions within a first predetermined time period due to the solidification of the toner in the developing cartridge 60.

[0142] In S9, ASIC 92 determines that the toner in the developing cartridge 60 has not solidified.

[0143] In S10, ASIC 92 stops processing the drive of motor M2. Additionally, the high-voltage power supply board 51 stops applying voltage to the cable 52.

[0144] In step S11, ASIC 92 moves the developing roller 61 from the contact position to the separation position. Specifically, ASIC 92 starts driving the main motor M1. Then, electromagnetic clutches EC1 and EC2 are energized to switch from the cut-off state to the transmission state, thereby transmitting the driving force of the main motor M1 to the developing separation gear train GT1. As a result, the developing roller 61 moves from the contact position to the separation position through the driving force of the main motor M1. In addition, while moving to the separation position, the developing drive gear train GT6, which is the drive transmission mechanism, moves the moving gear 424 from the first transmission position to the first cut-off position. In addition, the switching lever 160 moves to a position that does not prevent the rotation of the internal gear of the planetary gear mechanism 180. After a certain period of time, ASIC 92 stops energizing electromagnetic clutches EC1 and EC2, thereby switching from the transmission state to the cut-off state and stopping the driving of the main motor M1.

[0145] Next, based on Figure 8 The fault diagnosis of the motor is explained. First, in S21, ASIC 92 stops energizing electromagnetic clutches EC1 and EC2, thereby switching from the transmission state to the disengagement state and stopping the drive of the main motor M1. With the developing roller 61 in the contact position, as already explained, the developing roller 61 is moved from the contact position to the separation position, stopping the energization of electromagnetic clutches EC1 and EC2 and the drive of the main motor M1.

[0146] In S22, the ASIC 92 drives the processing motor M2. Here, since the developing roller 61 is in the separated position, the driving force from the processing motor M2 is not transmitted to the developing roller 61 (61Y, 61M, 61C, 61K).

[0147] In step S23, ASIC 92 determines whether the rotational speed of motor M2 has reached the target speed within a second specified time. If the target speed is reached within the second specified time, the process proceeds to step S24; otherwise, it proceeds to step S25.

[0148] In step S24, ASIC 92 determines that motor M2 is functioning normally. Motor M2 is a three-phase brushless motor. Based on the FG signal output from FG sensor M2S, ASIC 92 performs feedback control, changing the pulse width (duty cycle) of the PWM signal used as the control signal to achieve the target rotational speed. Therefore, if the target rotational speed is reached, motor M2 is determined to be operating normally.

[0149] In step S25, ASIC 92 determines that the processing motor M2 has malfunctioned. Similarly, if the target rotational speed is not reached, the processing motor M2 is also determined to have malfunctioned.

[0150] Next, the methods for determining toner solidification and diagnosing motor malfunctions described above will be explained. It is not limited to the following description; the determination of toner solidification and the diagnosis of motor malfunctions can be performed separately at any time.

[0151] First, Figure 9 This is a flowchart illustrating the control of the image forming apparatus 1 during toner replacement, executed when the front cover 11 at the front of the housing 10 is opened and closed. First, in S31, the ASIC 92 determines whether a toner replacement has been performed. In other words, it determines whether the developer cartridge 60 has been replaced. Specifically, it monitors whether the identification information has changed by reading the toner IC 62 included in each developer cartridge 60. If the developer cartridge 60 has been replaced, the process proceeds to S32; otherwise, the control ends. The content in parentheses will be explained later.

[0152] In S32, ASIC 92 performs a fault diagnosis of the motor. Since the motor fault diagnosis is the same as previously described, it is omitted from the description. In S33, if the fault diagnosis performed in S32 determines that the handling motor M2 is faulty, the process proceeds to S37; if the fault diagnosis determines that the handling motor M2 is normal, the process proceeds to S34.

[0153] In S34, ASIC 92 performs a toner solidification determination process. Since the toner solidification determination is the same as previously described, its explanation is omitted. In S35, if the toner solidification determination process performed in S34 determines that the toner in the developing cartridge 60 is solidified, the process proceeds to S36. If it determines that the toner in the developing cartridge 60 is not solidified, this control process ends.

[0154] Therefore, the toner solidification detection process is executed after the motor fault detection process, provided that the processing motor M2 is not identified as faulty. This prevents the toner solidification detection process from incorrectly detecting toner solidification due to a fault in the processing motor M2 causing it to fail to reach the second predetermined number of rotations within the first predetermined time.

[0155] In step S36, the display unit 14 displays an error image to notify the user of toner solidification. This reports to the user that the toner has solidified and prompts them to replace the toner.

[0156] In step S37, the display unit 14 displays an error image to notify the user of a motor malfunction. This reports the motor malfunction to the user and prompts them to perform maintenance.

[0157] Here, S31 can also determine whether the image forming apparatus 1 is new. Specifically, taking the power-on of the image forming apparatus 1 as a trigger, ASIC 92 determines whether it is the first startup of the image forming apparatus 1. Subsequent processing and Figure 9 The same applies. Furthermore, as a method for determining whether this is the first startup of the image forming apparatus 1, the startup history information in the NVRAM 94 can be left blank at the factory, and the startup history information can be stored for subsequent startups. Therefore, the ASIC 92 refers to the startup history information stored in the NVRAM 94, and if no startup history information is available, determines that this is the first startup of the image forming apparatus 1. This allows for the determination of toner solidification caused by temperature changes during transport or long-term storage before printing.

[0158] second, Figure 10 This is a flowchart illustrating the control of the image forming apparatus 1 in the mode for determining the solidification color. First, in S41, with... Figure 9 The flowchart is the same as above. ASIC 92 determines whether the developing cartridge 60 has been replaced or whether this is the first start-up of the image forming apparatus 1. If the determination is "yes", it proceeds to S42; if the determination is "no", it ends this control.

[0159] In step S42, ASIC 92 determines whether toner consolidation information is stored in the toner IC 62 of the developing cartridge 60. Toner consolidation information is consolidation history information stored in the toner IC 62, which serves as a storage unit, when the toner consolidation determination process determines that toner consolidation has occurred. If consolidation information is found to be stored, the process proceeds to step S52; otherwise, it proceeds to step S43.

[0160] In step S43, ASIC 92 sets the value of variable N to 1. Variable N is an integer from 1 to 4. Additionally, step S43 can also perform motor fault diagnosis, which is not shown in this flowchart.

[0161] In step S44, the display unit 14 shows an instruction that only the developer cartridge 60 corresponding to the value of variable N is installed. The user then installs or removes the developer cartridge 60, ensuring that only the indicated developer cartridge 60 is installed. N=1 is developer cartridge 60Y, N=2 is developer cartridge 60M, N=3 is developer cartridge 60C, and N=4 is developer cartridge 60K.

[0162] In S45, ASIC 92 performs toner solidification detection processing. This process is performed with one of the four developer cartridges installed, determining whether toner solidification has occurred for that specific cartridge.

[0163] In S46, if the toner solidification judgment process in S45 determines that the toner in the developing cartridge 60 has solidified, proceed to S47; if the toner solidification judgment process in S45 determines that the toner in the developing cartridge 60 has not solidified, proceed to S48.

[0164] In S47, ASIC 92 performs toner solidification information storage processing, which stores toner solidification information in the toner IC 62 of the developing cartridge 60, which was determined to have toner solidification in the toner solidification determination processing in S45. Therefore, individual toner solidification information is stored in the toner IC 62 of the developing cartridge 60.

[0165] In S48, the display unit 14 displays an error image and notifies the user of the toner solidification in the developing cartridge 60.

[0166] In S49, the display unit 14 displays an image so that the developing cartridge 60, which is determined to be unconsolidated toner in the toner consolidation judgment process in S45, is removed.

[0167] In S50, ASIC 92 determines whether the value of variable N is 4. If the determination is "no", it proceeds to S51. Alternatively, if the determination in S50 is "yes", i.e., N=4, it indicates that toner curing judgment processing has been performed on all four developer cartridges 60 (60Y, 60M, 60C, 60K) and the toner is determined to be uncured. Furthermore, in S51, ASIC 92 increments the value of variable N by 1. Then, the process proceeds to S44, and display unit 14 displays an instruction for installing a developer cartridge different from the one that has already undergone toner curing judgment processing. Thus, ASIC 92 can sequentially perform toner curing judgment processing even when one developer cartridge is installed.

[0168] In S52, the display unit 14 shows that the developing cartridge 60 storing toner settling information has been installed. That is, if the toner settling information is stored in the toner IC 62 of the developing cartridge 60 in S42, the ASIC 92 does not perform toner settling determination processing.

[0169] Based on the above, when a developing cartridge 60 is provided, the toner solidification detection process is performed. When toner solidification is detected, the developing cartridge 60 with solidified toner can be identified. Furthermore, by storing and detecting toner solidification information, unwanted repetitive toner solidification detection processes can be eliminated.

[0170] third, Figure 11 This is a flowchart illustrating the control of the image forming apparatus 1 in a mode that determines whether monochrome printing can be performed. Here, S71 to S76 are... Figure 9 S31 to S35 and S37 are the same, so the explanation is omitted.

[0171] In S77, the display unit 14 shows an instruction that only the developing cartridge 60K containing black toner is installed.

[0172] In S78, ASIC 92 performs toner solidification detection processing only for developer cartridge 60K. That is, in S76, with all developer cartridges 60 (60Y, 60M, 60C, 60K) installed, toner solidification detection processing is performed, and if toner solidification is detected, it is determined whether the toner solidification is caused by developer cartridge 60K.

[0173] In S79, if the toner in the developing cartridge 60K is determined to be solidified by the toner solidification determination process implemented in S78, the process proceeds to S80; if the toner in the developing cartridge 60K is determined not to be solidified, the process proceeds to S81.

[0174] In S80, the display unit 14 displays a printable error message and an error image notifying the user of toner solidification. This reports toner solidification to the user and prompts them to replace the toner. It can also display that at least 60K of toner in the developing cartridge containing black toner has solidified.

[0175] In S81, the display unit 14 displays an error image to notify the user of toner solidification. It may also display an image indicating that at least one or more of the developing cartridges 60Y, 60M, and 60C have experienced toner solidification.

[0176] In S82, ASIC 92 can only perform monochrome printing using black toner. Specifically, electromagnetic clutch EC1 is set to not switch from the cut-off state to the transmission state, while electromagnetic clutch EC2 is set to switch from the cut-off state to the transmission state. Therefore, the developer cartridges 60Y, 60M, and 60C are in the disengaged position and cannot receive driving force from the processing motor M2. Additionally, display unit 14 displays an image to notify the user that monochrome printing is possible.

[0177] As described in detail above, in the image forming apparatus 1 according to this embodiment, when the developing roller 61 is in the separation position, the photosensitive drum 50 is rotated using the processing motor M2 while voltage is applied to the charge cable 52 using the high voltage power supply board 51 (S3). Then, when the developing roller 61 is moved from the separation position to the contact position using the contact separation mechanism 5 (S5), toner consolidation judgment processing is performed based on the rotation of the processing motor M2 (S6, S7, S8, S9) to determine whether there is toner consolidation in the toner container.

[0178] Therefore, since a potential difference is generated between the photosensitive drum 50 and the developing roller 61 before they are separated, even if the photosensitive drum 50 and the developing roller 61 are in contact, toner can be prevented from flowing from the developing roller 61 into the photosensitive drum 50.

[0179] Furthermore, when the developing roller 61 is in the separation position, the high voltage power supply board 51 applies voltage to the belt charger 52 (S3), and after the processing motor M2, which corresponds to more than one revolution of the photosensitive drum 50, rotates more than a first predetermined number of revolutions (S4), the ASIC 92 uses the contact separation mechanism 5 to move the developing roller 61 from the separation position to the contact position (S5).

[0180] This allows a potential difference to be generated across the entire surface of the photosensitive drum 50 and the developing roller 61, thus preventing toner from flowing from the developing roller 61 into the photosensitive drum 50.

[0181] Furthermore, when the developing roller 61 is moved from the separation position to the contact position using the contact separation mechanism 5, if toner solidification is determined based on the rotation of the processing motor M2, toner solidification is not determined if the number of rotations of the processing motor M2 reaches or exceeds the second predetermined number of rotations within the first predetermined time (S6: Yes). If the number of rotations of the processing motor M2 does not reach or exceed the second predetermined number of rotations within the first predetermined time (S7: Yes), toner solidification is determined (S8).

[0182] Therefore, by monitoring the number of rotations of the processing motor M2, the solidification of the toner can be determined.

[0183] In addition, ASIC 92 determines the manufacturer of the processing motor M2 based on the signal from the processing motor M2 (S1). When performing feedback control that changes the pulse width of the control signal output to the motor drive circuit 102 according to the rotational speed of the processing motor M2, it sets the upper limit of the pulse width of the control signal to the upper limit of the manufacturer stored in NVRAM 94 (S2).

[0184] Therefore, based on the upper limit of the control signal pulse width corresponding to each processing motor M2 from the manufacturer, the processing motor M2 will not be over-rotated, thus preventing damage to the developer drive gear system GT6.

[0185] Furthermore, when the image forming apparatus 1 is first started (S31, S41, S71), or when the installation of the developing cartridge 60 is detected (S31, S41, S71), the ASIC 92 performs toner solidification judgment processing (S35, S46, S76, S79).

[0186] Therefore, even if the toner inside the image forming apparatus 1 or the developing cartridge 60 solidifies due to temperature changes during transport or the effects of long-term storage, toner solidification can be determined before printing.

[0187] In addition, ASIC 92 performs toner solidification detection processing when one of the multiple developer cartridges 60 is installed, and determines whether toner solidification exists for that developer cartridge (S46, S79).

[0188] Therefore, since ASIC 92 determines the solidification of toner in a single developing cartridge 60, it can determine whether toner is solidified in that developing cartridge 60.

[0189] When toner solidification detection processing is performed while one of the multiple developer cartridges 60 is installed (S46), if toner solidification is not detected (S46: No), the ASIC 92 displays an instruction on the display unit 14 to remove the developer cartridge 60 (S49) and an instruction to install a developer cartridge 60 different from the one that is installed (S51, S44).

[0190] Therefore, ASIC 92 can sequentially determine the toner solidification in each developing cartridge 60 and can determine the solidification of each toner.

[0191] In addition, when a developer cartridge 60 is installed, the ASIC 92 performs the toner solidification determination process (S46) described above. If toner solidification is determined (S46: Yes), toner solidification information storage process (S47) is performed, and the toner solidification information is stored in the toner IC 62 of the developer cartridge 60.

[0192] Therefore, by storing toner solidification information in toner IC 62, ASIC 92 can store the determination result that the toner has solidified in the toner solidified developing cartridge 60.

[0193] Furthermore, when a new developer cartridge 60 is installed after the toner solidification information storage process (S47) (S41), if the toner IC 62 of the newly installed developer cartridge 60 does not store toner solidification information (S42: No), the toner solidification judgment process (S46) is executed; if the toner solidification information is stored in the toner IC 62 of the installed developer cartridge 60 (S42: Yes), the toner solidification judgment process is not executed.

[0194] Therefore, by determining whether the toner solidification information stored in the toner IC 62 exists, ASIC 92 can eliminate unwanted repeated toner solidification judgment processing.

[0195] Furthermore, if the ASIC 92 determines that the toner has solidified during the toner solidification judgment process (S47: Yes), an indication that only the developer cartridge 60K containing black toner is installed is displayed on the display unit 14 (S77). Then, if the toner solidification judgment process (S78) is performed with only the developer cartridge 60K containing black toner installed and the result is no toner solidification (S79: No), the display unit 14 displays that monochrome printing is possible (S82). If the toner solidification is determined (S79: Yes), an error message indicating that printing is not possible is displayed on the display unit 14 (S80).

[0196] Therefore, even if toner solidifies in the developing cartridge 60 other than the developing cartridge 60K containing black toner, monochrome printing can still be performed using the developing cartridge 60 containing black toner.

[0197] Furthermore, ASIC 92 performs fault judgment processing, rotating the processing motor M2 while the developing roller 61 is in the separated position (S22), and judging whether the rotation speed of the processing motor M2 has reached the target speed within a second specified time (S23). If the target speed is not reached within the second specified time (S23: no), the processing motor M2 is judged to be faulty (S25). The toner solidification judgment processing (S35, S46, S76) is executed after the execution of the fault judgment processing (S33, S43, S73), and if the processing motor M2 is not judged to be faulty.

[0198] Therefore, since ASIC 92 determines toner solidification after confirming that the processing motor M2 has not malfunctioned, it can prevent the toner solidification from being mistakenly detected due to a malfunction of the processing motor M2.

[0199] This invention is not limited to the above-described embodiments, and various improvements and modifications can be made without departing from the spirit of this invention.

[0200] For example, the above embodiment describes a laser printer, but it could also be a multifunction printer with the same structure, or a home or commercial printer.

[0201] Furthermore, in the above embodiment, it was described that in the toner IC 62, which is an example of the storage unit of the developing cartridge 60, the consolidation history information is stored as toner consolidation information. However, in the toner IC 62, which is an example of the storage unit, an identification number corresponding to the toner consolidation history information may also be stored as the toner consolidation information. The toner consolidation history information can be stored in the NVRAM 94, and the toner consolidation history information can be retrieved from the NVRAM 94 according to the identification number.

Claims

1. An image forming apparatus, comprising: Photosensitive drum; An electric charge device is used to charge the photosensitive drum. A developing cartridge having a toner container for holding toner and a developing roller for supplying the toner to the photosensitive drum; A contact separation mechanism is used to move the developing roller between a contact position in contact with the photosensitive drum and a separation position away from the photosensitive drum; A processing motor is used to rotate the photosensitive drum and the developing roller; A drive transmission mechanism is used to transmit the driving force from the processing motor to the developing roller. When the developing roller is in the contact position, the drive transmission mechanism transmits the driving force from the processing motor to the developing roller. When the developing roller is in the separation position, the drive transmission mechanism does not transmit the driving force from the processing motor to the developing roller. A high-voltage power supply board is used to apply a voltage to the charge device to charge the photosensitive drum; as well as Control Department The control unit performs the following toner consolidation judgment process: while the developing roller is in the separation position, the processing motor rotates the photosensitive drum, and the high voltage power supply board applies the voltage to the belt capacitor. Then, while the developing roller is moved from the separation position to the contact position using the contact separation mechanism, the rotation of the processing motor is used to determine whether there is toner consolidation in the toner container.

2. The image forming apparatus according to claim 1, characterized in that, When the developing roller is in the separated position, the control unit applies the voltage to the belt carrier using the high-voltage power supply board. After the processing motor has rotated more than a first predetermined number of rotations corresponding to the rotation of the photosensitive drum more than one revolution, the control unit uses the contact separation mechanism to move the developing roller from the separated position to the contact position.

3. The image forming apparatus according to claim 1, characterized in that, When the control unit determines toner solidification based on the rotation of the processing motor while the developing roller is moved from the separation position to the contact position using the contact separation mechanism, it does not determine toner solidification if the number of rotations of the processing motor reaches a second predetermined number of rotations within a first predetermined time, and it determines toner solidification if the number of rotations of the processing motor does not reach the second predetermined number of rotations within the first predetermined time.

4. The image forming apparatus according to claim 1, characterized in that, The processing motor is a three-phase brushless motor, featuring three-phase drive coils, a Hall element for detecting the rotational position of the rotor, and an FG sensor that generates an induced electromotive force as the rotor rotates. The image forming apparatus further includes a motor drive circuit, which controls the amount of current supplied to the three-phase drive coil according to a control signal input from the control unit, and switches the timing of the current supply to the three-phase drive coil. When the processing motor rotates, the control unit detects the number of rotations of the processing motor based on the Hall signal from the Hall element input via the motor drive circuit. The rotational speed of the processing motor is detected based on the FG signal from the FG sensor input via the motor drive circuit. Feedback control is performed to change the pulse width of the control signal output to the motor drive circuit according to the rotational speed.

5. The image forming apparatus according to claim 4, characterized in that, It also includes non-volatile memory for storing, for each of the processing motor manufacturers, a predetermined upper limit value for the pulse width of the control signal, such that as the current supplied to the drive coil of the processing motor increases, the rotation of the processing motor does not cause damage to the drive transmission mechanism. The control unit determines the manufacturer of the processing motor based on signals from the processing motor. When performing feedback control that changes the pulse width of the control signal output to the motor drive circuit according to the rotational speed, the upper limit of the pulse width of the control signal is set to the upper limit value of the manufacturer stored in the non-volatile memory.

6. The image forming apparatus according to claim 1, characterized in that, Also includes: A fixing device for thermally fixing a toner image formed on a sheet by the photosensitive drum, comprising a heating rotator and a pressure rotator, the heating rotator having a heater, and the pressure rotator pressing the sheet between the pressure rotator and the heating rotator; as well as The main motor is used to rotate the rotating body of the fixing device. The contact separation mechanism can move the developing roller between the contact position and the separation position by the driving force from the main motor.

7. The image forming apparatus according to claim 1, characterized in that, The toner is a positively charged toner with a positive polarity. When the developing roller is in the separated position, the control unit applies the voltage to the belt conveyor using the high-voltage power supply board, thereby applying a positive first voltage to the belt conveyor using the high-voltage power supply board, so that the photosensitive drum is in a state with a higher voltage than the developing roller.

8. The image forming apparatus according to claim 1, characterized in that, The toner is a positively charged toner with a positive polarity. When the developing roller is in the separated position, the control unit applies the voltage to the belt conveyor using the high-voltage power supply board, applies a positive second voltage to the belt conveyor using the high-voltage power supply board, applies a positive developing voltage to the developing roller, and through the voltage difference between the second voltage and the developing voltage, makes the photosensitive drum have a higher voltage than the developing roller.

9. The image forming apparatus according to claim 1, characterized in that, The toner is a negatively charged toner. When the developing roller is in the separated position, the control unit applies the voltage to the belt conveyor using the high-voltage power supply board, and applies a negative third voltage to the belt conveyor using the high-voltage power supply board, so that the photosensitive drum is in a state with a voltage lower than that of the developing roller.

10. The image forming apparatus according to claim 1, characterized in that, Also includes the lid, When the cover is opened, the developing cartridge can be installed into and removed from the image forming apparatus. The control unit performs the toner consolidation judgment process when the image forming apparatus is started for the first time, or when it is detected that the developing cartridge has been replaced.

11. The image forming apparatus according to claim 10, characterized in that, The photosensitive drum is a plurality of photosensitive drums. The developing cartridges are multiple developing cartridges configured to correspond to the multiple photosensitive drums respectively. The control unit performs the toner solidification judgment process when one of the plurality of developing boxes is installed, and determines whether the toner has solidified for the developing box.

12. The image forming apparatus according to claim 11, characterized in that, It also includes the display section, When the control unit performs the toner solidification judgment process with one of the plurality of developing boxes installed, if the toner solidification is not judged, the following instruction is displayed on the display unit: Remove the developing box; Install a developing box different from the developing box.

13. The image forming apparatus according to claim 11, characterized in that, Each of the plurality of developing cartridges has a storage section. When the control unit performs the toner solidification determination process while the developing cartridge is installed, and determines that the toner has solidified, it performs a toner solidification information storage process to store the toner solidification information in the storage unit of the developing cartridge.

14. The image forming apparatus according to claim 13, characterized in that, If a new developer cartridge is installed after the toner consolidation information storage process and the storage unit of the newly installed developer cartridge does not store toner consolidation information, the control unit performs the toner consolidation judgment process. If the storage unit of the newly installed developer cartridge stores toner consolidation information, the control unit does not perform the toner consolidation judgment process.

15. The image forming apparatus according to claim 1, characterized in that, Also includes: build; as well as Display section, The photosensitive drum is a plurality of photosensitive drums. The developing cartridges are configured to correspond to the plurality of photosensitive drums respectively, and can be respectively installed into the image forming apparatus and removed from the image forming apparatus when the cover is opened. If the control unit determines that the toner has solidified after performing the toner solidification detection process with all of the plurality of developer cartridges installed, it will display an indication on the display unit that only the developer cartridge containing black toner is installed. Then, with only the developing cartridge containing the black toner installed, the toner solidification judgment process is performed. If the toner is not determined to be solidified, a display indicating that monochrome printing is possible is shown on the display unit. If the toner is determined to be solidified, an error display indicating that printing is not possible is shown on the display unit.

16. The image forming apparatus according to any one of claims 1 to 15, characterized in that, The control unit performs the following fault diagnosis process: While the developing roller is in the separation position, the processing motor is rotated, and it is determined whether the rotational speed of the processing motor reaches the target speed within a second predetermined time. If the target speed is not reached within the second predetermined time, the processing motor is determined to have malfunctioned. The toner consolidation judgment process is executed after the fault judgment process is executed, provided that the processing motor is not determined to be faulty.

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