JP2014089422A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect the presence of a waste toner box and the amount of toner in the waste toner box without using a photosensor.SOLUTION: An image forming apparatus includes: a waste toner box 40 that stores attachments on a conveyance belt 21; a full-state detection switch 55 that is alternatively turned on and off according to whether or not the waste toner box 40 is full of the attachments; a first electrode D1 that is provided to a main body frame 4 and connected with a power source line; a second electrode D2 that is provided to the main body frame 4 and connected with the ground; and a third electrode D3 that is provided to the waste toner box 40 and electrically connected with one end of the full-state detection switch 55. The third electrode D3 is connected with both of the first electrode D1 and second electrode D2 in the course of attaching the waste toner box 40 to short circuit both of the electrodes D1 and D2, while connected only with the first electrode D1 at the time of attachment of the waste toner box 40 to an attachment position.

Description

  The present invention relates to a technique for reducing the size of an apparatus.

  Japanese Patent Application Laid-Open No. 2004-228561 discloses a technique for detecting the presence or absence of a waste toner box with a normally closed switch and detecting the amount of toner in the waste toner box with a photo sensor.

JP 2008-116801 A

  The present invention provides a technique for detecting the presence / absence of a waste toner box and the amount of toner in the waste toner box without using a photosensor.

  An image forming apparatus disclosed in the present specification includes a main body frame, an image carrier that is mounted on the main body frame and carries a developer, a collection member that collects deposits attached to the image carrier, A storage unit that stores the deposits collected by the recovery member, and a switch that is provided in the storage unit and has one end connected to a reference potential, and the amount of deposits stored in the storage unit is greater than or equal to a specified amount A switch that is selectively turned on or off depending on whether or not, a first electrode provided on the main body frame and connected to a potential higher than a reference potential, and provided on the main body frame and connected to the reference potential A second electrode provided in the housing portion and electrically connected to the other end of the switch, wherein the housing portion is attached to the attachment position of the body frame in the mounting process. First A first electrode that contacts both the electrode and the second electrode to short-circuit the first electrode and the second electrode, and a third electrode that contacts only the first electrode when attached to the attachment position; The control unit performs a first determination process for determining the presence or absence of the storage unit based on whether or not a voltage change of the first electrode is detected.

  The short circuit means a state where two points of the electric circuit are electrically connected with a relatively low impedance (resistance). In addition, the meaning that “the first electrode and the second electrode are provided on the main body frame” refers to a spatial arrangement, and does not mean that there is an electrical connection relationship between the two electrodes via the main body frame. Absent.

  In this configuration, it is possible to determine whether or not the storage portion is present and whether the amount of deposits stored in the storage portion is equal to or greater than a specified amount without using a photosensor.

The following is preferable as an embodiment of the image forming apparatus.
The control unit executes a storage process of storing the determination result of the presence / absence of the storage unit in the storage unit in the storage unit, and detects a voltage change of the first electrode in the next first determination process. When it is determined, the presence / absence of the storage unit is determined to be a result opposite to the determination result stored in the storage unit. Since the voltage change of the first electrode occurs both when the housing portion is pulled out of the main body frame and when the housing portion is attached to the main body frame, the presence or absence of the housing portion cannot be specified only by the voltage change. In this configuration, when the voltage change of the first electrode is detected, attention is paid to the fact that the presence / absence of the accommodating portion is reversed before and after the detection. Then, the previous determination result is stored, and when a voltage change of the first electrode is detected, a determination opposite to the stored determination result is performed. In this way, the presence / absence of the accommodating portion can be specified.

-When the said control part judges that the said accommodating part exists in the said 1st judgment process, the quantity of the deposit | attachment accommodated in the said accommodating part based on the voltage of the said 1st electrode is more than regulation amount. A second determination process is performed to determine whether or not there is. In this way, it can be determined whether the amount of deposits is a specified amount or more.

-One end of the switch is connected to a reference potential via a fourth electrode provided in the housing portion. In the configuration in which one end of the switch is connected to the reference potential via the image carrier, the second determination process cannot be performed when the image carrier is removed. In this configuration, since one end of the switch is connected to the reference potential via the fourth electrode provided in the housing portion, the second determination process can be performed regardless of the presence or absence of the image carrier.

  One end of the switch is connected to a reference potential via the recovery member. The wiring may be simplified depending on the positional relationship between the recovery member and the switch (for example, the distance between the two is close).

A transfer unit that is integral with the image carrier and is detachable from the main body frame, transfers an image to a sheet conveyed by the image carrier, and a transfer voltage application circuit that applies a voltage to the transfer unit; The control unit determines a presence or absence of the image carrier based on a current value flowing through the transfer unit when a voltage is applied to the transfer unit via the transfer voltage application circuit. Execute the process. In addition to the presence / absence of the storage portion and the amount of deposits, it is possible to determine the presence / absence of an image carrier.

  The presence / absence of a storage unit for recovering the deposit collected by the recovery member from the image carrier mounted on the main body frame and the amount of the deposit accommodated in the storage unit disclosed in the specification In the determination method for determining whether the main body frame is attached to or detached from the main body frame, the first electrode and the second electrode provided on the main body frame are provided on the first main body frame. A first determination step for determining the presence or absence of the storage portion by detecting a voltage change of the first electrode, which occurs when three electrodes are short-circuited, and the storage portion is present in the first determination step. When it is determined, based on the voltage of the first electrode, the state of the switch that is turned on / off alternatively according to whether or not the amount of deposits accommodated in the accommodating portion is greater than or equal to a predetermined amount is detected. By before The amount of deposit to be housed in the housing portion includes a second determining step of determining whether a prescribed amount or more, the. In this determination method, it is possible to determine whether or not there is a storage portion and whether the amount of deposits stored in the storage portion is equal to or greater than a specified amount without using a photosensor.

  According to the present invention, the presence / absence of a waste toner box and the amount of toner in the waste toner box can be detected without using a photosensor.

FIG. 3 is a side sectional view of a main part of the printer according to the first embodiment. The perspective view of the housing | casing which shows the state which opened the upper surface cover Horizontal sectional view showing the structure of the waste toner box Enlarged view of the periphery of the rotating body (showing the closed position of the rotating body) Enlarged view of the periphery of the rotating body (showing the open position of the rotating body) Diagram showing ON / OFF operation of full detection switch by switch cam Circuit diagram showing relationship between full detection switch and controller The figure explaining the connection relation of each electrode accompanying attachment or detachment of a waste toner box Waveform diagram showing the change in the voltage of the first electrode when the waste toner box is attached / detached (when a full waste toner box is attached) Waveform diagram showing the change in the voltage of the first electrode when the waste toner box is attached / detached (when the full waste toner box is removed) Waveform diagram showing the change in the voltage of the first electrode when the waste toner box is attached / detached (when a waste toner box that is not full is attached) Waveform diagram showing the change in the voltage of the first electrode when the waste toner box is attached or detached (when the waste toner box that is not full is removed) Block diagram showing the electrical configuration of the printer 1 Flowchart showing the flow of a waste toner box mounting state detection sequence Chart summarizing waste toner box status patterns FIG. 9 is a flowchart showing a flow of a waste toner box mounting state detection sequence according to the second embodiment. The flowchart figure which shows the flow of the mounting state detection sequence of the same waste toner box Chart summarizing the status of the conveyor belt and waste toner box Block diagram showing a control system for feedback control of transfer current Block diagram showing control system for feedback control of cleaning current

<Embodiment 1>
The first embodiment will be described with reference to FIGS.
1. Schematic Configuration of Printer 1 The printer 1 is a direct tandem type color printer in which a plurality (four in this embodiment) of process units U are arranged in series along the sheet S conveyance direction. The printer 1 includes a housing 3, and a paper cassette 17, a belt cleaner 30, a belt unit 20, and an image forming unit 5 are housed in the housing 3 in order from the bottom.

  As shown in FIG. 2, the housing 3 is configured to cover a frame-shaped main body frame 4 with a side cover 3C and a top cover 3D. The body frame 4 has a structure in which a resin frame made of resin is attached to the inside of a pair of left and right sheet metal frames, and has a structure in which a pair of left and right sheet metal frames are connected by a connecting member. The upper surface cover 3D is swingably assembled to the upper rear side of the main body frame 4 via the swing shaft 3E, and closes the open position for opening the upper surface side of the main body frame 4 and the upper surface side of the main body frame 4. Displacement to the closed position Therefore, by displacing the upper surface cover 3D to the open position, the image forming unit 5, the belt unit 20, and the belt cleaner 30 can be detached from the main body frame 4 of the housing 3 in this order.

  The paper feed cassette 17 is provided at the bottom of the housing 3, and includes a paper feed tray 18 on which sheets S such as recording papers are stacked and a paper feed roller for feeding paper on the paper feed tray 18. 19 etc. The sheet S fed from the paper feed tray 18 is sent to the image forming unit 5 via a transport roller and a transport belt (an example of the “image carrier” in the present invention) 21. A handle 17 </ b> A is provided on the front wall of the sheet cassette 17, and the entire sheet cassette 17 can be pulled out to the front of the housing 3.

  The image forming unit 5 includes an exposure device 6, a process unit U, and the like. Each process unit U has the same structure and the like except that the color of the stored toner is different. The process unit U includes a photosensitive drum 7 on which a developer image (toner image) is carried, a charger 8, a drum cleaning roller 9, a developing roller 10 that supplies toner to the photosensitive drum 7, a supply roller 11, and a toner storage chamber 12. Including.

  The photosensitive drum 7 includes a cylindrical drum body formed of a positively chargeable photosensitive layer, and a metal drum shaft extending along the longitudinal direction of the drum body at the axis of the drum body.

  The charger 8 is a scorotron charger, and uniformly charges the surface of the photosensitive drum 7 to a positive polarity by applying a high voltage. Further, the drum cleaning roller 9 sucks and removes deposits (toner and paper dust) on the photosensitive drum 7 by electrostatic force when a high voltage is applied.

  The developing roller 10 includes a roller shaft and a rubber roller made of a conductive rubber material that covers the periphery of the roller shaft. The toner storage chamber 12 stores toner as a developer, and an agitator 13 for stirring the toner is provided inside. The developing roller 10 fulfills the function of supplying the toner supplied through the supply roller 11 onto the photosensitive drum 7 while being charged positively by the action of the developing voltage.

  The exposure device 6 exposes the photosensitive drums 7 and is provided individually for each photosensitive drum 7. The exposure device 6 has a configuration in which a large number of light emitters (for example, LEDs) are arranged in a row in parallel with the axial direction of the photosensitive drum 7.

  As shown in FIG. 1, the belt unit 20 is provided between the paper feed cassette 17 and the image forming unit 5, and includes a driving roller 23 </ b> A, a driven roller 23 </ b> B, a conveyance belt 21, and a transfer roller 15. The transfer roller 15 is an example of the “transfer portion” in the present invention.

  The driving roller 23A and the driven roller 23B are spaced apart in parallel in the front-rear direction, and the conveyance belt 21 is stretched therebetween. The upper surface of the conveyor belt 21 is in contact with each photosensitive drum 7. In addition, four transfer rollers 15 that sandwich the conveyor belt 21 between the photosensitive drums 7 are arranged inside the conveyor belt 21 so as to face the photosensitive drums 7.

  The fixing device 16 is disposed on the rear side (right side in FIG. 1) of the belt unit 20. The fixing device 16 includes a heating roller 16A that rotates while heating the developer image transferred to the sheet S, and a pressure roller 16B that presses the sheet S against the heating roller 16A.

  A series of image forming processes by the printer 1 configured as described above will be briefly described. When the printer 1 receives print data, the printer 1 starts the print process. As a result, the surface of each photosensitive drum 7 is uniformly positively charged by each charger 8 with its rotation. Each exposure unit 6 exposes each photosensitive drum 7 according to the print data. As a result, a predetermined electrostatic latent image corresponding to the print data is formed on the surface of each photosensitive drum 7, that is, the exposed portion of the uniformly positively charged surface of the photosensitive drum 7 is lowered in potential. .

  Next, by the rotation of the developing roller 10, the toner carried on the developing roller 10 and positively charged is supplied to the electrostatic latent image formed on the surface of each photosensitive drum 7. As a result, the electrostatic latent image on each photosensitive drum 7 is visualized, and a toner image by reversal development is carried on the surface of the photosensitive drum 7.

  Then, the sheet S fed from the paper feed cassette 17 is formed on each photosensitive drum 7 by passing between each photosensitive drum 7 and each transfer roller 15 disposed inside the transport belt 721. The toner image is transferred onto the sheet S. As the sheet S passes between the heating roller 16A and the pressure roller 16B, the toner image transferred onto the sheet S is thermally fixed. The sheet discharged from the fixing device 16 is turned approximately 180 degrees in the conveyance direction and discharged onto the discharge tray 3B from a discharge portion 3A provided on the upper side of the housing 3.

2. Configuration of Belt Cleaner A belt cleaner 30 is provided on the opposite side (lower side in FIG. 1) of the belt unit 20 to remove the adhering portion (toner and paper dust) adhering to the conveyor belt 21. ing. The belt cleaner 30 includes a backup roller 31, a cleaning roller 32, a collection roller 33, a blade 34, and a waste toner box 40. The belt cleaner 30 can be attached to and detached from the main body frame 4 of the housing 3. The backup roller 31, the cleaning roller 32, and the collection roller 33 are examples of the “collection member” of the present invention, and the waste toner box 40 is an example of the “accommodating portion” of the present invention.

  The backup roller 31 and the cleaning roller 32 are disposed to face each other with the conveyance belt 21 therebetween. When a high voltage is applied to the backup roller 31, an electric field is generated from the backup roller 31 toward the cleaning roller 32. Due to the action of this electric field, the deposits (toner and paper dust) on the conveyor belt 21 are electrostatically cleaned by the cleaning roller 32. Can suck. The adhering portion sucked by the cleaning roller 32 is then recovered by the recovery roller 33, then scraped off by the scraping blade 34, and stored in the first storage portion 41 of the waste toner box 40.

  The waste toner box 40 is provided with a first storage portion 41, a second storage portion 45, a partition wall 42 that partitions the two storage portions 41, 45, and a fullness detection switch 55 including a pair of metal plates 55A, 55B. ing. The first storage unit 41 stores the deposits collected from the conveyor belt 21. The second storage unit 45 is provided on the front side of the waste toner box 40 and includes an auger storage unit 46 and a storage unit 48. The auger housing portion 46 is provided with an auger screw 47. The auger screw 47 is formed in a screw shape extending in the left-right direction. The outer diameter of the auger screw 47 is formed to be approximately the same diameter as the inner diameter of the auger housing portion 46.

  The storage part 48 is provided on the right side of the auger storage part 46. A rotating body 51 is attached to the storage unit 48. The rotating body 51 is rotatable around a hinge 51A and includes an arm 52. The rotating body 51 is urged in the S direction of FIG. 4 by a spring (not shown), and the position of the rotating body 51 is restricted to the closed position of FIG. 4 by a stopper 49A provided in the storage portion 48. In this closed position, the tip of the arm 52 faces the guide plate 49B provided in the storage portion 48 with a predetermined clearance, and closes the space on the right side of the auger accommodating portion 46.

  The left side of the partition wall 42 is provided with a communication port 44 through which the first storage portion 41 and the second storage portion 45 are communicated, and the first storage portion 41 is further filled with deposits. When the deposit is collected, the deposit in the first housing portion 41 is supplied from the first housing portion 41 to the left end portion of the auger housing portion 46 of the second housing portion 45 through the communication port 44. . Then, the deposits supplied to the auger accommodating portion 46 are conveyed to the right side by the auger screw 47. And the adhering material conveyed pushes the arm 52, thereby rotating the rotator 51 in the R direction and displacing it to the open position of FIG.

  Further, the rotating body 51 is integrally provided with a switch cam 53 shown in FIG. The switch cam 53 includes a pressing portion 54 that protrudes outward in the radial direction. The switch cam 53 is in the position of the solid line shown in FIG. 6 when the rotating body 51 is in the closed position shown in FIG. 4 (the waste toner box 40 is not full), and the tip of the pressing portion 54 is the full detection switch 55. The metal plate 55B is pushed into the metal plate 55A side so that both the metal plates 55A and 55B are in contact with each other. The full detection switch 55 is an example of the “switch” in the present invention.

  On the other hand, when the rotary body 51 is in the open position shown in FIG. 5 (the waste toner box 40 is full), the switch cam 53 is in the position indicated by the one-dot chain line shown in FIG. The metal plates 55A and 55B are separated from the metal plate 55B of the switch 55. As described above, the full detection switch 55 is switched on and off depending on whether the waste toner box 40 is full.

  As shown in FIG. 7, one end of the fullness detection switch 55 is connected to the fourth electrode D4 provided on the side wall of the waste toner box 40, and the other end is provided on the side wall of the waste toner box 40. It is connected to the third electrode D3. The fourth electrode D4 is configured to be connected to the metal surface 4B of the main body frame 4, that is, the frame ground when the waste toner box 40 is assembled to the attachment position of the main body frame 4. Note that the spatial arrangement of the fourth electrode D4 is shifted so as not to contact the first electrode D1 and the second electrode D2 on the main body frame 4 side when the waste toner box 40 is attached to and detached from the main body frame 4. ing.

  The third electrode D3 has a shape that is long in the vertical direction (the direction in which the waste toner box 40 is attached or detached) shown in FIG. The third electrode D3 is set to be longer than the arrangement interval between the first electrode D1 and the second electrode D2 formed on the main body frame 4 side, and can contact both the electrodes D1 and D2. On the other hand, the main body frame 4 is provided with a first electrode D1. The first electrode D1 is provided on the resin surface (as an example, the right wall surface in FIG. 2) 4A of the main body frame 4, while the third electrode D3 is the outer peripheral wall (the right wall surface in FIG. 3) of the waste toner box 40. When the belt cleaner 30 is attached to the attachment position of the main body frame 4 as shown in FIG. 7, the third of the waste toner box 40 is set against the first electrode D <b> 1 provided on the main body frame 4. The electrode D3 contacts.

  The first electrode D1 provided on the main body frame 4 is connected to a power supply line of 3.3 V via resistors RA and RB. That is, it is connected to a potential higher than the ground that is the reference potential. Therefore, as shown in FIG. 7, the controller 80 detects whether the waste toner box 40 is full by detecting the voltage of the first electrode D1 (in this example, the voltage at the connection point Q of the resistor RA and the resistor RB). Can be detected.

  That is, when the waste toner box 40 is not full, the fullness detection switch 55 is turned on, so that the first electrode D1 is connected to the ground, and the voltage (voltage at the connection point Q) is at a low level. Therefore, when the voltage of the first electrode D1 is at a low level, it can be determined that the waste toner box 40 is not full. On the other hand, when the waste toner box 40 is full, the full detection switch 55 is turned off, so that the first electrode D1 is connected to a potential higher than the ground, and the voltage (voltage at the connection point Q) is at a high level. become. Therefore, when the voltage of the first electrode D1 is at a high level, it can be determined that the waste toner box 40 is full.

  Further, as shown in FIG. 7, a second electrode D <b> 2 is provided on the resin surface (for example, the right wall surface in FIG. 2) 4 </ b> A of the main body frame 4. The second electrode D2 is separated from the first electrode D1 by a certain distance in the attaching / detaching direction (G direction) of the waste toner box 40. The second electrode D2 is connected to a frame ground that is a reference potential.

  When the belt cleaner 30 is removed from the main body frame 4 (time t1), the third electrode D3 of the waste toner box 40 is the first electrode D1 and second electrode D2 of the main body frame 4 as shown in FIG. In a non-contact state. When the belt cleaner 30 is attached from the main body frame 4, first, the third electrode D3 of the waste toner box 40 comes into contact with the second electrode D2 of the main body frame 4 (time t2). Thereafter, the third electrode D3 of the waste toner box 40 contacts both the first electrode D1 and the second electrode D2 of the main body frame 4 to short-circuit both the electrodes D1, D2 (time t3). Then, at the time of mounting at the mounting position, the third electrode D3 contacts only the first electrode D1 (time t4). The short circuit means a state where two points of the electric circuit are electrically connected with a relatively low impedance (resistance). FIG. 8 is a schematic diagram in which the fourth electrode D4 is omitted.

  Therefore, when assembling the waste toner box (however, the waste toner box is full) 40 to the main body frame 4, as shown in FIG. 9A, the third electrode D3 of the waste toner box 40 starts from the start of the assembly. Until the electrodes D1 and D2 are contacted (time t1 to t2), the voltage of the first electrode D1 is at a high level.

  When the third electrode D3 of the waste toner box 40 contacts both the first electrode D1 and the second electrode D2 of the main body frame 4, both the electrodes D1 and D2 are short-circuited, and the voltage of the first electrode D1 becomes low level. (Time t3). Thereafter, at the time of mounting at the mounting position, the third electrode D3 is in contact with only the first electrode D1. When the waste toner box 40 is full, the full detection switch 55 is kept off, so that the voltage of the first electrode D1 becomes high level (time t4).

  On the other hand, when the waste toner box (however, the waste toner box is full) 40 is removed from the main body frame 4, the operation is reversed, so that at time t4 as shown in FIG. 9B. High level, low level at time t3, high level at time t2, time t1.

  Further, when the waste toner box (provided that the waste toner box is not full) 40 is assembled to the main body frame 4, as shown in FIG. Until the electrode D3 comes into contact with both the electrodes D1 and D2 (time t1 to t2), the voltage of the first electrode D1 is at a high level.

  Thereafter, when the third electrode D3 of the waste toner box 40 comes into contact with both the first electrode D1 and the second electrode D2 of the main body frame 4 and both the electrodes D1 and D2 are short-circuited, the voltage of the first electrode D1 becomes low level. (Time t3). Thereafter, at the time of mounting at the mounting position, the third electrode D3 is in contact with only the first electrode D1. When the waste toner box 40 is not full, the full detection switch 55 is kept on, so that the voltage of the first electrode D1 becomes low level (time t4).

  On the other hand, when removing the waste toner box (provided that the waste toner box is not full) 40 from the main body frame 4, the operation is reversed, so that as shown in FIG. It goes low at time t3 and goes high at time t2 and time t1.

  As described above, when the waste toner box 40 is attached to and detached from the main body frame 4, a change occurs in the first electrode D1 regardless of whether the waste toner box 40 is full or not. That is, switching from the high level to the low level or from the low level to the high level. Therefore, the controller 80 can detect whether the belt cleaner 30 is attached to or detached from the main body frame 4 by detecting a voltage change (hereinafter also referred to as “trigger”) of the first electrode D1.

  Then, the printer 1 stores the determination result of the presence / absence (attachment / non-attachment) of the waste toner box 40 in the NVRAM 87, and stores the presence / absence (attachment / non-attachment) of the waste toner box 40 in the NVRAM 87 when a trigger is detected. It is determined that the result is the opposite of the determined result.

  Specifically, when the “installation” information is stored and a trigger is detected, it is determined that the waste toner box 40 has been switched from “installation to non-installation” by the attachment / detachment operation. Then, the information “not installed” is stored in the NVRAM 87. On the other hand, when the “not-mounted” information is stored and the trigger is detected, it is determined that the waste toner box 40 has been switched from “not mounted to mounted” by the attachment / detachment operation. Then, the information “installation” is stored in the NVRAM 87.

  By making such a determination, it is possible to accurately determine whether the waste toner box 40 is attached or not. In this embodiment, the mounted state of the waste toner box 40 is stored in the NVRAM 87 corresponding to the flag “1”, and the unmounted state of the waste toner box 40 is stored in the NVRAM 87 corresponding to the flag “0”.

3. Next, the electrical configuration of the printer 1 will be described with reference to FIG. The printer 1 includes a main motor 71, an LED drive circuit 73 that drives LEDs of the exposure device 6, a high-voltage power supply circuit 75, a cover opening / closing switch 77, a communication unit 91, a display unit 93, an operation unit 95, and a controller 80.

  The main motor 71 rotationally drives each rotating body of the process unit U such as the photosensitive drum 7, the developing roller 10 and the supply roller 11, and each rotating body of the paper transport system such as the paper feed roller 19 and the transport roller.

  The high voltage power supply circuit 75 generates a high voltage to be applied to the charger 8, the drum cleaning roller 9, the developing roller 10, and the belt cleaner 30. The cover opening / closing switch 77 has a contact point that is turned on / off in conjunction with opening / closing of the cover 3D, and detects that the upper surface cover 3D is displaced from the open position to the closed position.

  The controller 80 includes a CPU 81, a ROM 83, a RAM 85, and an NVRAM 87. The ROM 83 stores a program for executing print processing, a program for executing a mounting state detection sequence of the waste toner box 40 described later, and the like. The RAM 85 stores various data.

  The controller 80 has a general function of the entire apparatus that executes a series of image forming processes and a function that executes a mounting state detection sequence of the waste toner box 40. The communication unit 91 communicates with an information terminal device such as a PC, and receives a print instruction and print data from the information terminal device. The display unit 93 includes a liquid crystal display, a lamp, and the like, and displays various setting screens, operation states, and the like through them.

4). Description of Waste Toner Box Mounting State Detection Sequence The waste toner box 40 mounting state detection sequence is executed by the controller 80 when the printer 1 is powered on. Here, the case where it is determined in the previous determination that the waste toner box 40 is attached to the main body frame 4 and the case where it is determined that the waste toner box 40 is not attached will be described separately.

(A) When it is determined in the previous determination that the waste toner box 40 is attached to the main body frame 4 (when “1” is stored as a flag)
After the mounting state detection sequence starts, first, the process proceeds to S10 and enters a standby state. During standby, the controller 80 monitors the voltage of the input port P1 to detect whether a trigger is detected, that is, whether the voltage of the first electrode D1 has changed.

  Then, the controller 80 starts a warming-up operation such as rotating the agitator 13 and stirring the toner on the condition that the print data is received or the cover open / close switch 77 detects the opening / closing of the top cover 3D (S20). ).

  Thereafter, the process proceeds to S <b> 30, and the controller 80 executes a process for determining whether the flag stored in the NVRAM 87 is “1”. If the stored flag is “1”, a YES determination is made in S30, and if the flag is “0”, a NO determination is made. Here, since “1” is stored as the flag, it is determined as YES, and the process proceeds to S40.

<When the waste toner box is attached / detached>
After shifting to S40, the controller 80 determines whether or not a trigger is detected during standby. When the waste toner box 40 is removed from the main body frame 4, a voltage change occurs in the first electrode D1 as described above, and a trigger is detected, so a YES determination is made in S40.

  If YES is determined in S40, the process proceeds to S50. In S50, the controller 80 executes a process for determining whether the voltage of the first electrode D1 is at a high level based on the voltage value of the input port P1.

  When the voltage of the first electrode D1 is at a high level, the process proceeds to S60, and it is determined that the state of the waste toner box 40 is “3”, that is, the waste toner box 40 is not attached (see FIG. 12). If the state of the waste toner box 40 is determined to be “3” in S60, the process proceeds to S70.

  In S <b> 70, the controller 80 executes a process of causing the display unit 93 to display an error message indicating that the waste toner box 40 is not attached. Thereafter, the process proceeds to S80, and the controller 80 executes a process of rewriting the flag stored in the NVRAM from “1” to “0”. As a result, a series of processing ends.

  On the other hand, if NO is determined in S50, that is, if the voltage of the first electrode D1 is at the low level, the process proceeds to S90 and the controller 80 determines that there is a failure. The reason for determining the failure is that when the waste toner box 40 is removed from the main body frame 4, the third electrode D3 of the waste toner box 40 is not in contact with the first electrode D1, and therefore the first electrode D1 This is because the voltage should be high except when there is no failure in the device.

  When it is determined in S90 that the waste toner box 40 is “failure”, the process proceeds to S100. In S100, a process for displaying an error message indicating that the apparatus is abnormal on the display unit 93 is executed. As a result, a series of processing ends.

<When the waste toner box is not attached / detached>
If the waste toner box 40 is not attached or detached, there is no voltage change in the first electrode D1, and no trigger is detected, so a NO determination is made in S40. If NO is determined in S40, the process proceeds to S110. In S110, the controller 80 executes a process of determining whether or not the voltage of the first electrode D1 is at a high level based on the voltage value of the input port P1.

  When the voltage of the first electrode D1 is at a high level, the process proceeds to S120, where it is determined that the state of the waste toner box 40 is “2”, that is, the waste toner box 40 is attached and full (FIG. 12). If the state of the waste toner box 40 is determined to be “2” in S120, the process proceeds to S130.

  In S <b> 130, a process for causing the display unit 93 to display an error message that prompts the controller 80 to replace the waste toner box 40 is executed. As a result, a series of processing ends.

  On the other hand, if NO is determined in S110, that is, if the voltage of the first electrode D1 is low level, the process proceeds to S140, and the state of the waste toner box 40 is “1”, that is, the waste toner box 40 is in the mounted state. And not full (see FIG. 12). When the state of the waste toner box 40 is determined to be “1” in S140, the process ends after the determination in S140.

  The “second determination process (second determination step)” of the present invention is realized by the process of S110, the process of S120, and the process of S140 executed by the controller 80.

(B) When it is determined in the previous determination that the waste toner box 40 is not attached to the main body frame 4 (when “0” is stored as a flag)
After the mounting state detection sequence starts, first, the process proceeds to S10 and enters a standby state. During standby, the controller 80 monitors the voltage of the input port P1 to detect whether a trigger is detected, that is, whether the voltage of the first electrode D1 has changed.

  Then, the controller 80 starts a warming-up operation such as rotating the agitator 13 and stirring the toner on the condition that the print data is received or the cover open / close switch 77 detects the opening / closing of the top cover 3D (S20). ).

  Thereafter, the process proceeds to S <b> 30, and the controller 80 executes a process for determining whether the flag stored in the NVRAM 87 is “1”. If the stored flag is “1”, a YES determination is made in S30, and if the flag is “0”, a NO determination is made. Here, since “0” is stored as the flag, it is determined as NO, and the process proceeds to S240.

<When the waste toner box is attached / detached>
In step S240, the controller 80 determines whether a trigger is detected during standby. When the waste toner box 40 is attached to the main body frame 4, a voltage change occurs in the first electrode D1 as described above, and a trigger is detected. Therefore, YES is determined in S240.

  If YES is determined in S240, the process proceeds to S250. In S250, the controller 80 executes a process of determining whether the voltage of the first electrode D1 is high level based on the voltage value of the input port P1.

  When the voltage of the first electrode D1 is at a high level, the process proceeds to S260, where it is determined that the state of the waste toner box 40 is “2”, that is, the waste toner box 40 is attached and full (FIG. 12). If the state of the waste toner box 40 is determined to be “2” in S260, the process proceeds to 270.

  In S <b> 270, a process for causing the display unit 93 to display an error message that prompts the controller 80 to replace the waste toner box 40 is executed. Thereafter, the process proceeds to S280, and the controller 80 executes a process of rewriting the flag stored in the NVRAM 87 from “0” to “1”. As a result, a series of processing ends.

  On the other hand, if NO is determined in S250, that is, if the voltage of the first electrode D1 is at a low level, the process proceeds to S290, and the state of the waste toner box 40 is “1”, that is, the waste toner box 40 is in the mounted state. And not full (see FIG. 12). If it is determined in S290 that the state of the waste toner box 40 is “1”, then the process proceeds to S280, and the controller 80 performs a process of rewriting the flag stored in the NVRAM 87 from “0” to “1”. Executed. As a result, a series of processing ends.

  The “second determination process (second determination step)” of the present invention is realized by the processing of S250, the processing of S260, and the processing of S290 executed by the controller 80.

<When the waste toner box is not attached / detached>
If the waste toner box 40 is not attached or detached, there is no voltage change in the first electrode D1 and no trigger is detected, so a NO determination is made in S240. If NO is determined in S240, the process proceeds to S310. In S310, the controller 80 executes a process for determining whether or not the voltage of the first electrode D1 is at a high level based on the voltage value of the input port P1.

  When the voltage of the first electrode D1 is at a high level, the process proceeds to S320, where it is determined that the state of the waste toner box 40 is “3”, that is, the waste toner box 40 is not attached (see FIG. 12). If the state of the waste toner box 40 is determined to be “3” in S320, the process proceeds to S330.

  In S330, the controller 80 executes a process for causing the display unit 93 to display an error message indicating that the waste toner box 40 is not attached. As a result, a series of processing ends.

  On the other hand, if NO is determined in S310, that is, if the voltage of the first electrode D1 is at a low level, the process proceeds to S340 and the controller 80 determines that a failure has occurred. The reason for determining the failure is that when the waste toner box 40 is not attached, the third electrode D3 of the waste toner box 40 is not in contact with the first electrode D1, and therefore the voltage of the first electrode D1 is This is because, except when there is no failure, the level should be high.

  When it is determined in S340 that the waste toner box 40 is “failure”, the process proceeds to S350. In S350, a process of displaying an error message indicating that the apparatus is abnormal on the display unit 93 is executed. As a result, a series of processing ends.

  The “first determination process (first determination step)” of the present invention is realized by the processes of S30 (YES), S40, S60, S80, S120, and S140 executed by the controller 80. Further, the “first determination process (first determination step)” of the present invention is realized by the processes of S30 (NO), S240, S260, S280, S290, and S320 executed by the controller 80.

5. Explanation of Effect The voltage change of the first electrode D1 occurs both when the waste toner box 40 is detached from the main body frame 4 and when it is attached to the main body frame 4, so whether or not the waste toner box 40 is present only by the voltage change ( Cannot specify (attached / not attached). In this printer 1, attention is paid to the fact that the presence or absence of the waste toner box 40 is reversed before and after the detection when the voltage change of the first electrode D1 is detected. Then, the previous determination result is stored, and when a voltage change of the first electrode D1 is detected, a determination opposite to the stored determination result is performed.

  In the printer 1, when the waste toner box 40 is not full, the full detection switch 55 is turned on, so the voltage of the first electrode D1 (voltage at the connection point Q) is at a low level. Therefore, when the voltage of the first electrode D1 is at a low level, it can be determined that the waste toner box 40 is not full. On the other hand, when the waste toner box 40 is full, the full detection switch 55 is turned off, so that the voltage of the first electrode D1 (voltage at the connection point Q) is at a high level. Therefore, when the voltage of the first electrode D1 is at a high level, it can be determined that the waste toner box 40 is full.

  From the above, the printer 1 can detect the presence or absence of the waste toner box and whether or not the waste toner box is full without using a photosensor.

  In the printer 1, one end of the fullness detection switch 55 is connected to the frame ground via the fourth electrode D 4 in the waste toner box 40. As a method of connection to the ground, in addition to a method of connecting to the frame ground via the fourth electrode D4 of the waste toner box 40 as in the first embodiment, for example, a method of connecting to the frame ground via the conveyance belt 21 There is. However, when connecting to the frame ground via the conveyor belt 21, when the conveyor belt 21 is detached from the main body frame 4, one end of the fullness detection switch 55 is not connected to the frame ground. In this case, since the voltage of the first electrode D1 is at a high level regardless of whether the switch 55 is on or off, it cannot be determined whether or not the waste toner box 40 is full.

  In this respect, in the printer 1, one end side of the fullness detection switch 55 is connected to the fourth electrode D <b> 4 in the waste toner box 40. Since the fourth electrode D4 is always connected to the frame ground when the waste toner box 40 is attached to the attachment position of the main body frame 4, even if the transport belt 21 is removed from the main body frame 4, the fourth electrode D4 is connected to the frame ground. By detecting whether the voltage is high or low, it can be determined whether the waste toner box 40 is full.

<Embodiment 2>
Next, a second embodiment of the present invention will be described with reference to FIGS.
In the first embodiment, it is determined whether the waste toner box 40 is attached to the main body frame 4 and whether the waste toner box 40 is full. In the second embodiment, in addition to these determinations, the presence or absence of the conveyor belt 21 is determined. Accordingly, the waste toner box mounting state detection sequence (see FIGS. 13 and 14) of the second embodiment is different from the waste toner box mounting state detection sequence (FIG. 11) of the first embodiment in steps S51 and S52. , S53, S111, S112, S113, S115, S117, S118, S251, S252, S253, S255, S256, S257, S311, S312 and S313 are added. Note that these added processes are indicated by thick frames in FIGS. 13 and 14.

  Hereinafter, the newly added process will be described. First, in the process of S51 shown in FIG. 13, when the previously stored flag is “1”, a trigger is detected, and the voltage of the first electrode D1 is at a high level (S30: YES, S40: YES, S50: YES), that is, when the waste toner box 40 is removed from the main body frame 4 and there is no abnormality in the apparatus.

  In S <b> 51, the controller 80 performs processing for detecting the presence or absence of the transfer current It flowing through the roller shaft of the transfer roller 15 when a voltage is applied to the transfer roller 15 via the transfer voltage application circuit 120. When the transfer current It is flowing, the process proceeds to S60, and it is determined that the state of the conveyance belt 21 and the waste toner box 40 is “3”. That is, it is determined that the transport belt 21 is present and the waste toner box 40 is not attached (see FIG. 15). When the transfer current It is flowing, it can be determined that the conveyance belt 21 is present because the transfer current It flows from the transfer roller 15 to the photosensitive drum via the conveyance belt 21, and thus the transfer current It flows. This is because it can be determined that the conveyor belt 21 is attached.

  On the other hand, when the transfer current It does not flow, the process proceeds to S52, and it is determined that the states of the conveyance belt 21 and the waste toner box 40 are “6”. That is, it is determined that there is no conveyance belt 21 and the waste toner box 40 is not attached (see FIG. 15). In S52, when it is determined that the state of the conveyance belt 21 and the waste toner box 40 is “6”, the process proceeds to S53.

  In S <b> 53, the controller 80 executes a process of causing the display unit 93 to display an error message indicating that the conveyance belt 21 and the waste toner box 40 are not attached. Thereafter, the process proceeds to S80, and the controller 80 executes a process of rewriting the flag stored in the NVRAM from “1” to “0”. As a result, a series of processing ends.

  Next, in the processing of S111 shown in FIG. 13, when the previously stored flag is “1”, the trigger is not detected, and the voltage of the first electrode D1 is at a high level (S30: YES, S40: NO, S110: YES), that is, when the waste toner box 40 remains attached to the main body frame 4 and the waste toner box 40 is full.

  In S111, when a voltage is applied to the transfer roller 15 via the transfer voltage application circuit 120, the presence or absence of the transfer current It flowing through the roller shaft of the transfer roller 15 or the voltage is applied to the backup roller 31 via the cleaning voltage application circuit 150. The controller 80 performs a process for detecting the presence or absence of the cleaning current Ic flowing through the belt cleaner 30 at this time. When the transfer current It or the cleaning current is flowing, a YES determination is made in S111, and then the process proceeds to S120, where it is determined that the states of the transport belt 21 and the waste toner box 40 are “2”. That is, it is determined that the conveyance belt 21 is present, the waste toner box 40 is in the mounted state, and is full (see FIG. 15).

  When the cleaning current Ic is flowing, it can be determined that the conveyor belt 21 is present because the cleaning current Ic flows from the backup roller 31 to the cleaning roller 32 via the conveyor belt 21, and therefore the cleaning current Ic is This is because it can be determined that the conveyor belt 21 is attached if it is flowing.

  On the other hand, if the transfer current It or the cleaning current is not flowing, a NO determination is made in S111, and then the process proceeds to S112, where it is determined that the states of the transport belt 21 and the waste toner box 40 are “5”. That is, it is determined that the transport belt 21 is not present, the waste toner box 40 is in the mounted state, and is full (see FIG. 15). If the state of the conveyor belt 21 and the waste toner box 40 is determined to be “5” in S112, the process proceeds to S113.

  In S <b> 113, the controller 80 executes processing for causing the display unit 93 to display an error message that prompts the replacement of the waste toner box 40 while the transport belt 21 is not attached. As a result, a series of processing ends.

  Next, in the process of S115 shown in FIG. 13, when the previously stored flag is “1”, the trigger is not detected, and the voltage of the first electrode D1 is at the low level (S30: YES, S40: NO, S110). : NO), that is, when the waste toner box 40 is still attached to the main body frame 4 and the waste toner box 40 is not full.

  In S115, as in S111, the presence or absence of the transfer current It flowing through the roller shaft of the transfer roller 15 when a voltage is applied to the transfer roller 15 via the transfer voltage application circuit 120, or the backup roller 31 via the cleaning voltage application circuit 150. The controller 80 performs processing for detecting the presence or absence of the cleaning current Ic flowing in the belt cleaner 30 when a voltage is applied to the belt cleaner 30. If the transfer current It or the cleaning current is flowing, a YES determination is made in S115, and then the process proceeds to S140 where it is determined that the states of the transport belt 21 and the waste toner box 40 are “1”. That is, it is determined that the transport belt 21 is present and the waste toner box 40 is in the mounted state and is not full (see FIG. 15).

  On the other hand, if the transfer current It or the cleaning current is not flowing, a NO determination is made in S111, and then the process proceeds to S117, where it is determined that the states of the conveyance belt 21 and the waste toner box 40 are “4”. That is, it is determined that the conveying belt 21 is not present, the waste toner box 40 is attached, and is not full (see FIG. 15). If it is determined in S117 that the state of the conveyor belt 21 and the waste toner box 40 is “2”, the process proceeds to S118.

  In S <b> 118, the controller 80 executes processing for causing the display unit 93 to display an error message indicating that the conveyor belt 21 is not attached. As a result, a series of processing ends.

  Next, in the process of S251 shown in FIG. 14, when the previously stored flag is “0”, a trigger is detected, and the voltage of the first electrode D1 is at a high level (S30: NO, S240: YES, S250). : YES), that is, when the waste toner box 40 is attached to the main body frame 4 and the waste toner box 40 is full, the process is executed.

  In S 251, whether or not there is a transfer current It flowing through the roller shaft of the transfer roller 15 when a voltage is applied to the transfer roller 15 via the transfer voltage application circuit 120, or a voltage is applied to the backup roller 31 via the cleaning voltage application circuit 150. The controller 80 performs a process for detecting the presence or absence of the cleaning current Ic flowing through the belt cleaner 30 at this time. When the transfer current It or the cleaning current is flowing, a YES determination is made in S251, and then the process proceeds to S260, where it is determined that the states of the transport belt 21 and the waste toner box 40 are “2”. That is, it is determined that the conveyance belt 21 is present, the waste toner box 40 is in the mounted state, and is full (see FIG. 15).

  On the other hand, if the transfer current It or the cleaning current Ic is not flowing, a NO determination is made in S251, and then the process proceeds to S252 where it is determined that the states of the conveyor belt 21 and the waste toner box 40 are “5”. . That is, it is determined that there is no conveyance belt 21 and the waste toner box 40 is in a mounted state and is full (see FIG. 15). If it is determined in S252 that the state of the conveyor belt 21 and the waste toner box 40 is “5”, the process proceeds to S253.

  In step S <b> 253, the controller 80 executes processing for causing the display unit 93 to display an error message prompting replacement of the waste toner box 40 when the transport belt 21 is not attached. Thereafter, the process proceeds to S280, and the controller 80 executes a process of rewriting the flag stored in the NVRAM from “0” to “1”. As a result, a series of processing ends.

  Next, in the process of S255 shown in FIG. 14, when the previously stored flag is “0”, a trigger is detected, and the voltage of the first electrode D1 is low level (S30: NO, S240: YES, S250: In the case of NO), that is, when the waste toner box 40 is attached to the main body frame 4 and the waste toner box 40 is not full, it is executed.

  In S255, as in S251, the presence or absence of the transfer current It flowing through the roller shaft of the transfer roller 15 when a voltage is applied to the transfer roller 15 via the transfer voltage application circuit 120, or the backup roller via the cleaning voltage application circuit 150. The controller 80 performs processing for detecting the presence or absence of the cleaning current Ic flowing through the belt cleaner 30 when a voltage is applied to the belt 31. If the transfer current It or the cleaning current is flowing, a YES determination is made in S255, and then the process proceeds to S290 where it is determined that the states of the transport belt 21 and the waste toner box 40 are “1”. That is, it is determined that the conveyor belt 21 is present and the waste toner box 40 is in a mounted state and is not full (see FIG. 15).

  On the other hand, if the transfer current It or the cleaning current Ic is not flowing, a NO determination is made in S255, and then the process proceeds to S256 where it is determined that the state of the transport belt 21 and the waste toner box 40 is “4”. . That is, it is determined that there is no conveyance belt 21 and the waste toner box 40 is in a mounted state and is not full (see FIG. 15). If it is determined in S256 that the state of the conveyor belt 21 and the waste toner box 40 is “4”, the process proceeds to S257.

  In S257, the controller 80 executes a process of displaying an error message on the display unit 93 indicating that the conveyor belt 21 is not attached. Thereafter, the process proceeds to S280, and the controller 80 executes a process of rewriting the flag stored in the NVRAM from “0” to “1”. As a result, a series of processing ends.

  Next, the processing of S311 shown in FIG. 14 is performed when the previously stored flag is “0”, the trigger is not detected, and the voltage of the first electrode D1 is at a high level (S30: NO, S240: NO, In the case of S310: YES), that is, when the waste toner box 40 is not attached to the main body frame 4 and there is no abnormality in the apparatus, it is executed.

  In S <b> 311, the controller 80 performs processing for detecting the presence or absence of the transfer current It flowing through the roller shaft of the transfer roller 15 when a voltage is applied to the transfer roller 15 via the transfer voltage application circuit 120. If the transfer current It is flowing, a YES determination is made in S311 and then the process proceeds to S320, where it is determined that the states of the conveyor belt 21 and the waste toner box 40 are “3”. That is, it is determined that the conveyance belt 21 is present and the waste toner box 40 is not attached (see FIG. 15).

  On the other hand, if the transfer current It is not flowing, a NO determination is made in S311 and then the process proceeds to S312 to determine that the state of the transport belt 21 and the waste toner box 40 is “6”. That is, it is determined that the transport belt 21 and the waste toner box 40 are not attached (see FIG. 15). In S312, if it is determined that the state of the conveyance belt 21 and the waste toner box 40 is “6”, the process proceeds to S313.

  In step S <b> 313, the controller 80 executes a process for causing the display unit 93 to display an error message indicating that the conveyance belt 21 and the waste toner box 40 are not attached. As a result, a series of processing ends.

  As described above, in the second embodiment, in addition to determining whether the waste toner box 40 is attached to the main body frame 4 and determining whether the waste toner box 40 is full, the presence / absence of the conveyance belt 21 is determined. I can do it.

  The “third determination process” of the present invention is realized by the processes of S51, S60, S52, S111, S120, S112, S115, S140, and S117 executed by the controller 80. Further, the “third determination process” of the present invention is realized by the processes of S251, S260, S252, S225, S290, S256, S311, S320, and S312 executed by the controller 80.

  Next, an example of a method for detecting the presence or absence of the transfer current It and a method for detecting the presence or absence of the cleaning current Ic will be described. FIG. 16 is a block diagram illustrating a control system that feeds back a transfer current It flowing through the roller shaft of the transfer roller 15. Reference numeral 120 shown in FIG. 16 denotes a transfer voltage application circuit. The transfer voltage application circuit 120 is a part of the high-voltage power supply circuit 75 and includes a PWM signal smoothing circuit 121, a differential circuit 123, a feedback circuit 124, and an output circuit 125. The PWM signal smoothing circuit 121 is an integrating circuit composed of a resistor and a capacitor, and smoothes the PWM signal output from the PWM port P2 of the controller 80. The PWM signal is a signal for setting a target value of the transfer current It with a PWM value (a duty ratio of the PWM signal). The feedback circuit 124 detects the output current of the output circuit 125, that is, the transfer current It, and feeds it back to the differential circuit 124.

  The PWM signal smoothed by the PWM signal smoothing circuit 121 (a DC signal having a voltage corresponding to the PWM value) is input to the differential circuit 123 together with the feedback signal from the feedback circuit 124. The differential circuit inputs a signal corresponding to the difference between the target value (smoothed PWM signal) and the feedback signal to the output circuit 125.

  The output circuit 125 functions to generate a transfer voltage of a predetermined level in response to an input value from the differential circuit 124 and apply it to the roller shaft of the transfer roller 15.

  When performing the transfer process of transferring an image to the sheet S, the controller 80 outputs a target value of the transfer current It to the transfer voltage marking circuit 120 as a PWM signal. Specifically, a PWM signal having a PWM value corresponding to the target value is output. Then, feedback control is performed by the differential circuit 123, the output circuit 125, and the feedback circuit 124, and the output voltage of the output circuit 125 is automatically adjusted, so that the transfer current It is feedback controlled to the target value.

  The printer 1 also feedback-controls the transfer current It to the target value when determining whether or not the transfer current It is flowing, and at that time, whether the PWM value (duty ratio of the PWM signal) exceeds the upper limit value. Thus, the presence or absence of the transfer current It is determined.

  That is, if the transfer belt 15 is applied and a transfer voltage is applied to the transfer roller 15 and a transfer current It flows from the transfer roller 15 to the photosensitive drum 7 in response thereto, the transfer voltage application circuit 120 from the controller 80. When the target value of the transfer current It is output using the PWM signal, feedback control by the differential circuit 123, the output circuit 125, and the feedback circuit 124 works normally, and the transfer current It is feedback-controlled to the target value. In this case, the PWM value of the PWM signal does not rise to the upper limit value.

  On the other hand, when the transport belt 21 is not attached, even if a transfer voltage is applied to the transfer roller 15, the transfer current It hardly flows from the transfer roller 15 to the photosensitive drum 7. For this reason, the feedback of the transfer current It becomes small (that is, the resistance value on the transfer roller side appears large). In this case, the controller 80 increases and adjusts the PWM value of the PWM signal in an attempt to set the transfer current It as a target value, and as a result, only the numerical value of the PWM value of the PWM signal increases without the transfer current It flowing. Exceeds value.

  As described above, when the conveyor belt 21 is not attached, the PWM value of the PWM signal exceeds the upper limit value, and therefore the presence or absence of the conveyor belt 21 can be detected depending on whether the PWM value of the PWM signal exceeds the upper limit value. I can do it. In this printer 1, since the presence or absence of the conveyance belt 21 is detected by utilizing the feedback control system, it is not necessary to provide a detection sensor or the like.

  In addition to the method for determining whether the transfer current It is flowing using the feedback control characteristic as described above, for example, the transfer current It is measured using a detection resistor, and the transfer current It almost flows. If not, the controller 80 can determine that the conveyor belt 21 is not attached. That is, whether or not the conveyor belt 21 is attached can be determined based on the transfer current It flowing through the transfer roller 15 when a voltage is applied to the transfer roller 15 via the transfer voltage application circuit 120.

  Next, an example of a method for detecting the presence or absence of the cleaning current Ic will be described. FIG. 17 is a block diagram showing a control system for feeding back the cleaning current Ic flowing from the backup roller 31 to the cleaning roller 32. Reference numeral 150 shown in FIG. 17 denotes a cleaning voltage application circuit. The cleaning voltage application circuit 150 is a part of the high voltage power supply circuit 75 and includes a PWM signal smoothing circuit 151, an amplifier 153, and an output circuit 155. The PWM signal smoothing circuit 151 is an integrating circuit composed of a resistor and a capacitor, and smoothes the PWM signal output from the PWM port P3 of the controller 80. The PWM signal smoothed by the PWM signal smoothing circuit 151 is amplified by the amplifier 153 and then input to the output circuit 155.

  The output circuit 155 generates a predetermined level of cleaning voltage in response to the input value from the amplifier 153 and applies it to the roller shaft of the backup roller 31. The cleaning voltage application circuit 150 is connected to the ground via the current detection resistor R2. The cleaning current Ic output from the output circuit 155 returns to the output circuit 155 through the current detection resistor R2. Therefore, the level of the cleaning current Ic can be detected by the controller 80 by monitoring with the controller 80 of the voltage of the current detection resistor R2.

  When the transport belt 21 is cleaned, the controller 80 adjusts the output voltage of the output circuit 155 by increasing / decreasing the PWM value of the PWM signal, thereby feedback-controlling the cleaning current Ic so that the detected current value becomes the target value. To do.

  As in the case of determining whether or not the transfer current It is flowing, the printer 1 controls the cleaning current Ic to a target value when determining whether or not the cleaning current Ic is flowing. The presence or absence of the cleaning current Ic is determined depending on whether the PWM value exceeds the upper limit value.

  That is, if the conveyor belt 21 is attached and a cleaning voltage is applied to the backup roller 31, in response to the cleaning current Ic flowing from the backup roller 31 to the cleaning roller 32, feedback control by the controller 80 is normally performed. Therefore, if the PWM value of the PWM signal is increased by a predetermined amount from the initial value, the cleaning current Ic finally reaches the target value before the PWM value of the PWM signal reaches the upper limit value.

  On the other hand, if the cleaning current Ic does not flow from the backup roller 31 to the cleaning roller 32 even when the conveying belt 21 is not attached and a cleaning voltage is applied to the backup roller 31, there is no feedback of the cleaning current Ic. In this case, the controller 80 continues to increase and adjust the PWM value of the PWM signal in an attempt to set the cleaning current Ic to the target value. Therefore, only the numerical value of the PWM value of the PWM signal increases without exceeding the cleaning current Ic and exceeds the upper limit value. Thus, in the printer 1, since the presence or absence of the cleaning current Ic is detected using the feedback control system, it is not necessary to provide a dedicated component for detection.

  Further, as shown in FIG. 17, a Zener diode DZ is connected between the roller shaft of the cleaning roller 32 and the roller shaft of the collection roller 33. Specifically, in the Zener diode DZ, the roller shaft of the cleaning roller 32 is connected to the cathode, while the roller shaft of the collection roller 33 is connected to the anode connected to the ground. Therefore, when a cleaning voltage is applied to the backup roller 31, a voltage of about 400 V is generated between the rollers 32 and 33.

  In the second embodiment, one end of the fullness detection switch 55 is connected to the roller shaft of the collection roller 33 and is connected to the ground that is the reference potential via the collection roller 33. With this configuration, the wiring can be simplified as compared to the case where one end of the full detection switch 55 is connected to the ground in the waste toner box 40 as in the first embodiment.

<Other embodiments>
The present invention is not limited to the embodiments described with reference to the above description and drawings. For example, the following embodiments are also included in the technical scope of the present invention.

  (1) In the first and second embodiments, the full toner detection switch detects whether the waste toner box is full. For the detection of the amount of waste toner box, in addition to being full, for example, a threshold value (specified amount) may be provided to detect whether the stored amount is equal to or greater than the specified amount.

  (2) In the first and second embodiments, an example in which the controller 80 is configured by one CPU 81, ROM 83, RAM 85, NVRAM 87, and the like has been described, but a plurality of CPUs 81 may be provided. Further, the CPU 81 and a hardware circuit such as an ASIC may be combined, or only the hardware circuit may be used.

1. Printer (an example of the “image forming apparatus” of the present invention)
5 ... Image forming section 7 ... Photosensitive drum 8 ... Charging device 10 ... Developing roller 15 ... Transfer roller (an example of the "transfer section" in the present invention)
DESCRIPTION OF SYMBOLS 20 ... Belt unit 21 ... Conveyance belt (an example of "image carrier" of the present invention 30) Belt cleaner 31 ... Backup roller (an example of "collecting member" of the present invention)
32. Cleaning roller (an example of the “collecting member” of the present invention)
33. Collection roller (an example of the “collection member” of the present invention)
40. Waste toner box (an example of the “accommodating portion” of the present invention)
55. Full detection switch (an example of the “switch” of the present invention)
80 ... Controller 120 ... Transfer voltage application circuit D1 ... First electrode D2 ... Second electrode D3 ... Third electrode D4 ... Fourth electrode

Claims (7)

Body frame,
An image carrier mounted on the main body frame and carrying a developer;
A recovery member for recovering deposits adhering to the image carrier;
An accommodating portion for accommodating the deposit collected by the collecting member;
A switch that is provided in the housing portion and has one end connected to a reference potential, and is alternatively turned on or off depending on whether or not the amount of deposits housed in the housing portion is greater than or equal to a specified amount. When,
A first electrode provided on the body frame and connected to a potential greater than a reference potential;
A second electrode provided on the main body frame and connected to a reference potential;
A third electrode provided in the housing portion and electrically connected to the other end of the switch, wherein the first electrode and the second electrode are mounted in a mounting process of mounting the housing portion at a mounting position of the body frame. A first electrode and the second electrode in contact with both of the electrodes, while short-circuiting the first electrode and the second electrode, the third electrode that contacts only the first electrode when mounted to the mounting position;
A control unit,
The controller is
An image forming apparatus that performs a first determination process for determining the presence or absence of the housing portion based on whether or not a voltage change of the first electrode is detected. The control unit executes a storage process of storing a determination result of the presence or absence of the storage unit in the storage unit by the first determination process,
2. When the voltage change of the first electrode is detected in the next first determination process, it is determined that the presence / absence of the storage unit is a result opposite to the determination result stored in the storage unit. The image forming apparatus described. The controller is
When it is determined in the first determination process that the accommodating portion is present, it is determined whether or not the amount of deposits accommodated in the accommodating portion is greater than or equal to a predetermined amount based on the voltage of the first electrode. The image forming apparatus according to claim 1, wherein a second determination process is performed.   4. The image forming apparatus according to claim 1, wherein one end of the switch is connected to a reference potential via a fourth electrode provided in the housing portion. 5.   The image forming apparatus according to claim 1, wherein one end of the switch is connected to a reference potential via the recovery member. A transfer unit that is detachably attached to the main body frame integrally with the image carrier, and that transfers an image to a sheet conveyed by the image carrier;
A transfer voltage application circuit for applying a voltage to the transfer unit,
The controller executes a third determination process for determining the presence / absence of the image carrier based on a current value flowing through the transfer unit when a voltage is applied to the transfer unit via the transfer voltage application circuit. The image forming apparatus according to claim 1. Judgment method for determining whether or not there is a storage unit for collecting the deposit collected by the recovery member from the image carrier mounted on the main body frame, and whether the amount of the deposit stored in the storage unit is equal to or greater than a specified amount Because
When the housing part is attached to and detached from the attachment position of the main body frame, the first electrode and the second electrode provided in the main body frame are generated by short-circuiting the third electrode provided in the housing part. A first determination step of determining presence / absence of the accommodating portion by detecting a voltage change of the first electrode;
If it is determined in the first determination step that the housing portion is present, whether or not the amount of deposits housed in the housing portion is greater than or equal to a specified amount based on the voltage of the first electrode. And a second determination step of determining whether or not the amount of deposits accommodated in the accommodating portion is greater than or equal to a predetermined amount by detecting the state of the switch that is selectively turned on / off in response. .

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