JP2014240876A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to identify a loaded developing device with a simple configuration without the need to incorporate storage means such as a memory in the developing device.SOLUTION: A developing device 34 is detachably from an image forming unit 3, and includes: a scraper 66 for rotating in accordance with rotation of a screw feeder 64A; and a toner concentration sensor 67 for detecting magnetic permeability of a developer. The scraper 66 periodically contacts a detection surface 68 per rotation. A rotation drive force of a stepping motor 77 is transmitted to the screw feeder 64A via a gear 78 to allow the scraper 66 to rotate. The toner concentration sensor 67 outputs a signal which periodically changes in accordance with the rotation of the scraper 66. A controller 5 determines a cycle of an output waveform from the toner concentration sensor 67 and identifies the developing device 34 on the basis of the cycle.

Description

  The present invention relates to an image forming apparatus that performs development processing using a mounted developing device.

  2. Description of the Related Art Image forming apparatuses such as copiers and printers that form images on paper by electrophotography are known. The image forming apparatus includes a developing device that develops an electrostatic latent image formed on an image carrier. The developing device is replaced for reasons such as failure or deterioration over time. For this reason, the image forming apparatus is configured so that the developing device can be attached and detached.

  Various types of image forming apparatuses such as applications, functions, structures, and development methods are distributed in the market, and the developing apparatus mounted on the image forming apparatus is configured to correspond to the type of image forming apparatus. Has been. When there is a developing device having mounting compatibility for each of a plurality of types of image forming apparatuses, a developing device that should originally be incompatible may be erroneously mounted. In this case, the image forming apparatus performs development processing using an incompatible developing apparatus, so that the image quality is deteriorated. Conventionally, for example, detection methods described in Patent Documents 1 to 7 are known as methods for detecting whether or not a developing device is attached to or detached from an image forming apparatus. In the detection method, information on a memory mounted in the developing device is read out at the time of mounting, and presence / absence of mounting / dismounting or a mounting state is detected based on the information.

JP 2003-29490 A JP-A-10-186769 JP 2009-53514 A JP 2003-122202 A JP 2007-264591 A JP 2008-129056 A JP 2012-230250 A

  However, the detection methods described in the above-mentioned patent documents require a storage means such as a memory in the developing device. Therefore, the image forming apparatus requires not only the storage unit, but also a communication unit for communicating with the storage unit, a connection connector for electrical connection, and the like, so the configuration of the mounting unit of the developing device becomes complicated. In addition, there is a problem in that the number of parts increases and the cost of the parts is required.

  An object of the present invention is to provide an image forming apparatus capable of identifying a developing device with a simple configuration without requiring a storage means such as a memory.

  An image forming apparatus according to one aspect of the present invention is an image forming apparatus that performs development processing using a mounted developing device. The developing device includes a developing container, a detection unit, a contact member, and a drive transmission unit. The developer container contains a developer and has a detection surface inside. The detection means detects the magnetic permeability of the developer in the developer container via the detection surface. The contact member periodically contacts the detection surface by being rotated in the developing container. The drive transmission means transmits a rotational driving force to the contact member. The image forming apparatus includes a drive unit and a control unit. The drive means supplies a rotational drive force to the drive transmission means of the mounted developing device. The control unit determines whether or not the developing device is usable based on a period of a signal waveform output from the detection unit during rotation of the contact member by the driving unit.

  According to the present invention, it is possible to identify a mounted developing device with a simple configuration without mounting storage means such as a memory in the developing device.

1 is a cross-sectional view illustrating a configuration of an image forming apparatus including a developing device according to an embodiment of the present invention. The perspective view of a developing device. FIG. 3 is a cross-sectional view schematically showing a schematic configuration of a developing device. Sectional drawing which shows typically the stirring means of a developing device. The block diagram which shows the structure of a control part and a drive transmission mechanism. Sectional drawing which shows the structure around a scraper. FIG. 4 is a waveform diagram showing a waveform of an output signal of a toner density sensor. The figure which shows rotation operation | movement of a scraper. The flowchart which shows an example of the procedure of the identification process which a control part performs.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings for understanding of the present invention.

<Schematic Configuration of Image Forming Apparatus 100>
First, a schematic configuration of the image forming apparatus 100 according to the embodiment of the present invention will be described. As shown in FIG. 1, the image forming apparatus 100 includes an image reading unit 1, an ADF (Automatic Document Feeder) 2, an image forming unit 3, a paper feeding unit 4, a control unit 5, an operation display unit 6, and the like. Yes. The operation display unit 6 is a touch panel or the like that displays various types of information according to control instructions from the control unit 5 and inputs various types of information to the control unit 5 according to user operations. Here, FIG. 1A is a front view of the image forming apparatus 100, and FIG. 1B is a plan view of the image reading unit 1. For convenience of explanation, the vertical direction in a state where the image forming apparatus 100 is installed is defined as the vertical direction 7, and the side where the operation display unit 6 is provided is the front side (front side), and the front-rear direction 8 is defined. The horizontal direction 9 is defined with the side surface on which the operation display unit 6 is provided as the front. The image forming apparatus 100 is only an example of the image forming apparatus of the present invention, and the image forming apparatus of the present invention may be a printer, a FAX apparatus, a copying machine, or the like.

  The image reading unit 1 acquires image data from the paper P. The image reading unit 1 is an image reading unit including a paper cover 2A, a contact glass 11, a reading unit 12, a mirror 13, a mirror 14, an optical lens 15, a CCD (Charge Coupled Device) 16, and the like. The contact glass 11 is provided on the upper surface of the image reading unit 1, and is a transparent paper base on which a paper P that is an image reading target of the image forming apparatus 100 is placed.

  The paper cover 2A covers the contact glass 11 as necessary. The image reading unit 1 reads an image from the paper P placed on the contact glass 11 under the control of the control unit 5.

  The reading unit 12 includes an LED light source 121 and a mirror 122, and is configured to be movable in the sub-scanning direction (the left-right direction 9 in FIG. 1) by a moving mechanism (not shown) such as a stepping motor. When the reading unit 12 is moved in the sub-scanning direction by the moving mechanism, the light emitted from the LED light source 121 toward the contact glass 11 is scanned in the sub-scanning direction.

  The LED light source 121 includes a large number of white LEDs arranged along the main scanning direction of the image forming apparatus 100 (front-rear direction 8 in FIG. 1). The LED light source 121 emits white light for one line toward the paper P at the reading position 12 </ b> A on the contact glass 11. Note that the reading position 12A moves in the sub-scanning direction as the reading unit 12 moves in the sub-scanning direction.

  The mirror 122 reflects the reflected light when the light is irradiated from the LED light source 121 to the paper P at the reading position 12 </ b> A toward the mirror 13. The light reflected by the mirror 122 is guided to the optical lens 15 by the mirror 13 and the mirror 14. The optical lens 15 collects incident light and makes it incident on the CCD 16.

  The CCD 16 is a photoelectric conversion element that converts received light into an electrical signal (voltage) corresponding to the amount of light and outputs it to the control unit 5. Specifically, the CCD 16 generates image data based on an electrical signal corresponding to an image on the paper P based on light reflected from the paper P when light is emitted from the LED light source 121.

  The ADF 2 is provided on the paper cover 2A. The ADF 2 is an automatic document feeder including a paper tray 21, a feeding mechanism 22, a plurality of transport rollers 23, a paper press 24, a paper discharge unit 25, and the like. The ADF 2 drives each of the feeding mechanism 22 and the transport roller 23 with a stepping motor (not shown), thereby causing the paper P set on the paper tray 21 to pass through the reading position 12A on the contact glass 11 and the paper discharge unit 25. Transport to. At this time, the image reading unit 1 reads the image of the paper P passing through the reading position 12A.

  The sheet presser 24 is provided at a position above the reading position 12 </ b> A on the contact glass 11 with an interval through which the sheet P can pass. The sheet presser 24 is formed in an elongated shape in the main scanning direction, and a white sheet is attached to the lower surface (the surface on the contact glass 11 side). In the image forming apparatus 100, the image data of the white sheet is read as white reference data. The white reference data is used in known shading correction or the like.

  The image forming unit 3 is an electrophotographic system that executes image forming processing (printing processing) based on image data read by the image reading unit 1 or image data input from an information processing apparatus such as an external personal computer. Image forming means. The image forming unit 3 includes a photosensitive drum 31, a charging device 32, an LSU (Laser Scanner Unit) 33, a developing device 34 (an example of a developing device), a transfer roller 35, a charge eliminating device 36, a fixing roller 37, a pressure roller 38, And a toner container 39 and the like. In addition, the image forming unit 3 includes a stepping motor 77 (an example of a driving unit, see FIG. 5) for supplying a rotational driving force to the developing device 34.

  In the image forming unit 3, an image is formed on the paper S fed from the paper feeding unit 4 according to the following procedure, and the paper S after the image formation is discharged to the paper discharge tray 40. Specifically, first, the photosensitive drum 31 is uniformly charged to a predetermined potential by the charging device 32. Next, the light based on the image data is irradiated on the surface of the photosensitive drum 31 by the LSU 33. As a result, an electrostatic latent image is formed on the surface of the photosensitive drum 31. Then, the electrostatic latent image on the photosensitive drum 31 is developed (visualized) as a toner image by the developing device 34 driven by the stepping motor 77. Subsequently, the toner image formed on the photosensitive drum 31 is transferred onto the paper S by the transfer roller 35. Thereafter, the toner image transferred to the paper S is heated by the fixing roller 37 and melted and fixed to the paper S when the paper S passes between the fixing roller 37 and the pressure roller 38 and is discharged. To do. The electric potential of the photosensitive drum 31 is neutralized by the neutralization device 36. Details of the developing device 34 will be described later.

  The paper feeding unit 4 feeds the paper S on which an image is formed in the image forming unit 3. The paper feed unit 4 feeds a plurality of sheets S placed in a paper feed cassette (not shown) mounted in a cassette mounting unit (not shown) one by one to the image forming unit 3.

  Next, the general function of the control unit 5 will be described with reference to FIG. The control unit 5 includes a CPU 51, a ROM 52, a RAM 53, an EEPROM 54, a motor driver 55, and the like. The control unit 5 performs overall control of the image forming apparatus 100 by causing the CPU 51 to execute a predetermined control program stored in the ROM 52. Specifically, the ROM 52 stores in advance an image formation processing program for forming an image, a drive control program for driving a stepping motor 77 connected to the developing device 34, and the like. The ROM 52 stores in advance an identification processing program for executing an identification process (see FIG. 9) described later. Further, the ROM 52 stores period information corresponding to the developing device 34 that can be used in the image forming unit 3. Here, the period information is used as a threshold value for determining whether or not the mounted developing device 34 is usable in the image forming unit 3. For example, it shows the period of the output waveform of the output signal of the toner density sensor 67 described later when the usable developing device 34 suitable for the image forming unit 3 is mounted. The period of the output waveform at this time is a specific period (natural period) of the developing device 34 obtained based on the transmission ratio of the gear 78 of the developing device 34. That is, the period depends on the transmission ratio of the gear 78. More precisely, it depends on the transmission ratio of a drive transmission mechanism including a gear 78 provided between the output shaft of the stepping motor 77 and a scraper 66 described later. When this transmission ratio changes, the period of the output waveform also changes. The ROM 52 that stores such period information corresponds to the storage means of the present invention.

  The RAM 53 is a volatile storage unit, and the EEPROM 54 is a non-volatile storage unit, and is used as a temporary storage memory for various processes executed by the CPU 51. The motor driver 55 drives the stepping motor 77 under the control of the CPU 51. Further, a toner density sensor 67 (described later) provided in the developing device 34 is connected to the control unit 5, and an output signal (voltage signal) detected and output by the toner density sensor 67 is input to the control unit 5. The control unit 5 may be configured by an electronic circuit such as an integrated circuit (ASIC, DSP), or may be a control unit provided separately from the main control unit that controls the image forming apparatus 100 in an integrated manner. .

<Configuration of developing device 34>
Next, the developing device 34 will be described in detail with reference to FIGS. 4 is a cross-sectional view taken along line AA in FIG. 6 is a cross-sectional view taken along the line BB in FIG.

  The developing device 34 develops using a so-called two-component developer composed of two components of a toner and a magnetic carrier. As shown in FIG. 2, the developing device 34 is formed in a shape that is long in the front-rear direction 8. A replenishing port 70 is formed outside the developing device 34, and a shutter 69 for opening and closing the replenishing port 70 is provided. The shutter 69 is slid by a solenoid (not shown) to open the supply port 70 when non-magnetic toner is supplied from the toner container 39 (see FIG. 1A) to the developing device 34. When the toner is not replenished, the shutter 69 is slid by a solenoid to close the replenishment port 70.

  As shown in FIG. 3, the developing device 34 includes a developer reservoir 63 (an example of a developing container), a screw feeder 64A (an example of a stirring unit), a screw feeder 64B, a scraper 66 (an example of a contact member), a toner concentration. A sensor 67 (an example of a detection unit), a developing roller 61, a magnetic roller 62, a developer regulating blade 71, and the like are provided. These are provided inside the housing 60 of the developing device 34. The developer reservoir 63 is formed at the bottom of the housing 60 and is configured integrally with the housing 60. The developer storage unit 63 is a container that stores (accommodates) a two-component developer including nonmagnetic toner and magnetic carrier replenished from the toner container 39. A magnetic roller 62 that is a developer carrying member is disposed above the developer reservoir 63. The developing roller 61 that is a toner carrier is disposed opposite to the magnetic roller 62 at a position obliquely above the magnetic roller 62. The developer regulating blade 71 is disposed to face the magnetic roller 62.

  As shown in FIG. 5, the developing device 34 includes a gear 78 (an example of a drive transmission unit). The gear 78 transmits the rotational driving force of the stepping motor 77 to the scraper 66. Specifically, the developing roller 61, the magnetic roller 62, the screw feeder 64A, and the screw feeder 64B are connected to an output shaft (not shown) of a stepping motor 77 through a gear 78. In other words, the rotational driving force supplied from the stepping motor 77 is transmitted to the developing roller 61, the magnetic roller 62, the screw feeder 64A, and the screw feeder 64B via the gear 77. Thereby, the screw feeder 64A, the screw feeder 64B, the developing roller 61, and the magnetic roller 62 rotate in conjunction with each other. Further, the rotational driving force is transmitted to the scraper 66 attached to the screw feeder 64A via the screw feeder 64A.

  In the present embodiment, the developing device 34 is configured to be detachable from the image forming unit 3. The image forming unit 3 executes a developing process and an image forming process using the mounted developing device 34. For example, when the gear 78 is damaged, or when the developing device 34 fails due to a rotation failure in the developing roller 61, the magnetic roller 62, the screw feeder 64A, the screw feeder 64B, etc., the failed developing device 34 is removed and a new one is removed. The developing device 34 can be replaced. However, since the developing device 34 is configured to be detachable, it is another developing device having mounting compatibility (mounting compatibility) and cannot be normally used in the image forming unit 3 (hereinafter referred to as “the developing device 34”). In some cases, it is also referred to as “nonconforming development device”. Here, the mounting compatibility includes compatibility of electrical connection when the pin assignment of the connector that electrically connects the image forming unit 3 and the developing device 34 (arrangement of pin signals with respect to the pin position of the connector) is the same. There is compatibility of mechanical connection when the mounting mechanism of the developing device 34 is the same. When such an incompatible developing device having compatibility is mounted on the image forming unit 3, there is a possibility that the image quality due to image formation by the image forming unit 3 may be deteriorated.

  For example, the transmission ratio (gear ratio) of the gear 78 of the developing roller 61 of the developing device 34 is set to a value suitable for the image forming operation in the image forming unit 3, and the developing device is different if the type of the image forming device 100 is different. The transmission ratio in is also different. For this reason, when the incompatible developing device is mounted on the image forming unit 3, the rotational driving force transmitted to the developing roller 61 is different, and the rotational speed of the developing roller 61 is changed to form the image forming unit 3. The image quality is degraded. The developing device 34 and the incompatible developing device have the same configuration except that the transmission ratio is different. In this embodiment, even when the incompatible developing device having mounting compatibility (mounting compatibility) is mounted on the image forming unit 3, an identification process (see FIG. 9) described later is executed by the control unit 5. Thus, it is accurately identified whether or not the developing device mounted in the image forming unit 3 is suitable. The details of the identification process will be described later.

  The stepping motor 77 rotates the developing roller 61 and the magnetic roller 62 in the normal rotation direction (corresponding to the directions of the arrows 91 and 92 in FIG. 3 and the first rotation direction) during development when the development is performed, under the control of the control unit 5. Let In conjunction with this, the screw feeder 64 </ b> A and the screw feeder 64 </ b> B also rotate in the forward rotation direction defined by the gear 78 (directions of arrows 93 and 94 in FIGS. 3 and 4). As a result, the toner is supplied to the photosensitive drum 31. Further, the stepping motor 77 is controlled by the control unit 5 so that the reverse rotation direction opposite to the normal rotation direction (the direction opposite to the arrows 91 and 92 in FIG. , Corresponding to the second rotation direction), the developing roller 61 and the magnetic roller 62 are rotated. In conjunction with this, the screw feeder 64A and the screw feeder 64B also rotate in the reverse rotation direction determined by the gear 78 (the direction opposite to the arrows 93 and 94 in FIGS. 3 and 4). As a result, it is possible to stir the toner staying in the place where the stirring cannot be performed by the rotation in the positive rotation direction or the toner that has precipitated.

  As shown in FIG. 4, the developer storage unit 63 includes two adjacent developer storage chambers 63 </ b> A and 63 </ b> B extending in the longitudinal direction (front-rear direction 8) of the developing device 34. Each of the developer storage chambers 63A and 63B is formed in a cylindrical shape that is long in the front-rear direction 8. The developer storage chambers 63 </ b> A and 63 </ b> B are formed integrally with the housing 60 and are partitioned from each other by a partition plate 111 extending in the front-rear direction 8. However, it is not completely partitioned, and as shown in FIG. 4, partition plates 111 are not provided at both ends in the front-rear direction 8. Specifically, both end portions of the developer storage chambers 63A and 63B are communicated with each other through communication paths 112 and 113, respectively.

  Screw feeders 64A and 64B are accommodated in the developer storage chambers 63A and 63B, respectively. The screw feeders 64A and 64B are made of synthetic resin. The screw feeder 64A is rotatably supported by both end walls in the longitudinal direction of the developer storage chamber 63A. The screw feeder 64B is rotatably supported by both end walls in the longitudinal direction of the developer storage chamber 63B. Accordingly, the screw feeders 64A and 64B can rotate inside the developer storage chambers 63A and 63B. The screw feeders 64A and 64B are conveyed around the developer while being agitated by being rotated around the axis inside the developer storage chambers 63A and 63B. The screw feeders 64A and 64B are provided with spiral wings around the axis. The screw feeders 64A and 64B are rotated by receiving the rotational driving force supplied from the stepping motor 77 through the gear 77. The rotation directions of the screw feeders 64A and 64B are set in opposite directions. Thus, the developer is circulated and conveyed in the direction indicated by the arrow 96 in FIG. 4 while being stirred between the developer storage chamber 63A and the developer storage chamber 63B. By this stirring, the toner of the developer can be charged.

  As shown in FIG. 4, a detection surface 68 is formed in the vicinity of one end portion (front end portion) of the developer storage chamber 63A. As will be described later, the toner concentration sensor 67 is fitted into an opening formed in the bottom surface of the developer storage chamber 63A, whereby a part (specifically, the upper surface) of the casing 67A of the toner concentration sensor 67 is stored in the developer storage. The chamber 63A is exposed. The exposed portion appears as a detection surface 68 on the bottom surface of the developer storage chamber 63A. That is, the detection surface 68 is formed on the bottom surface of the developer storage chamber 63A. The detection surface 68 is formed in a flat shape so that the toner concentration sensor 67 can accurately measure the toner concentration of the developer. In the present embodiment, the detection surface 68 is provided at a position separated upward from the bottom surface of the cylindrical developer storage chamber 63A. In other words, the distance from the rotation center of the rotation shaft to the detection surface 68 is shorter than the distance from the rotation center of the rotation shaft of the screw feeder 64A to the inner wall of the developer storage chamber 63A.

  A support part 79 for attaching the scraper 66 is formed on the screw feeder 64A in the vicinity of the detection surface 68. The support portion 79 is integrally formed of the same resin as that of the screw feeder 64A, and has a shape protruding in a direction perpendicular to the rotation axis of the screw feeder 64A.

  Further, the scraper 66 is formed such that the joining surface 66B on the end portion side on the screw feeder 64A side is joined to the support portion 79, and the other end portion extends in the vertical direction. The joining surface 66B is a surface opposite to the contact surface 66A where the scraper 66 contacts the detection surface 68 when the screw feeder 64A is rotated in the forward rotation direction. The scraper 66 is a flexible plate-like member made of, for example, a polyethylene terephthalate film. The scraper 66 is attached to the support portion 79 of the screw feeder 64A with a double-sided tape or the like. Therefore, when the screw feeder 64A is rotated in the forward rotation direction at the time of development, the scraper 66 moves in the forward rotation direction, the contact surface 66A side hits the detection surface 68, and abuts against the detection surface 68 while being deformed by bending (FIG. 6). reference).

  The magnetic roller 62 is disposed along the longitudinal direction (front-rear direction 8) of the developing device 34. The magnetic roller 62 is rotated in the clockwise direction in FIG. 3 (the direction of the arrow 92 in FIG. 3) during development. A fixed so-called magnet roll (not shown) is arranged inside the magnetic roller 62. The magnet roll has a plurality of magnetic poles, and in this embodiment, has a drawing pole 73, a regulation pole 74, and a main pole 75. The scooping pole 73 is disposed so as to face the developer storage portion 63, the regulating electrode 74 is opposed to the developer regulating blade 71, and the main pole 75 is opposed to the developing roller 61.

  The magnetic roller 62 magnetically pumps the developer from the developer reservoir 63 onto the magnetic roller peripheral surface 62A by the magnetic force of the pumping pole 73. The developer thus pumped up is magnetically held as a developer layer (magnetic brush layer) on the magnetic roller peripheral surface 62 </ b> A, and is conveyed toward the developer regulating blade 71 as the magnetic roller 62 rotates.

  The developer regulating blade 71 is disposed on the upstream side of the developing roller 61 when viewed from the rotation direction of the magnetic roller 62. The developer regulating blade 71 regulates the layer thickness of the developer layer magnetically attached to the magnetic roller peripheral surface 62A. The developer regulating blade 71 is a plate member made of a magnetic material extending along the front-rear direction 8 of the magnetic roller 62, and is attached to the housing 60. Further, the developer regulating blade 71 has a regulating surface 71A (that is, the leading end surface of the developer regulating blade 71) that forms a regulating gap 72 having a predetermined size with the magnetic roller peripheral surface 62A.

  The developer regulating blade 71 is made of a magnetic material and is magnetized by the regulating pole 74 of the magnetic roller 62. As a result, a magnetic path is formed between the regulating surface 71A of the developer regulating blade 71 and the regulating pole 74, that is, in the regulating gap 72. When the developer layer adhering to the magnetic roller circumferential surface 62 </ b> A by the scooping pole 73 is conveyed into the regulation gap 72 as the magnetic roller 62 rotates, the layer thickness of the developer layer is regulated in the regulation gap 72. . Thus, a uniform developer layer having a predetermined thickness is formed on the magnetic roller peripheral surface 62A.

  The developing roller 61 is disposed so as to extend along the longitudinal direction (front-rear direction 8) of the developing device 34 and in parallel with the magnetic roller 62. The developing roller 61 is rotated in the clockwise direction in FIG. 3 (the direction of the arrow 91 in FIG. 3) during development. The developing roller 61 receives the toner from the developer layer and carries the toner layer on the developing roller peripheral surface 61A while rotating in contact with the developer layer held on the magnetic roller peripheral surface 62A. During development in which development is performed, the toner in the toner layer is supplied to the peripheral surface of the photosensitive drum 31.

  The developing roller 61 and the magnetic roller 62 are rotated by a stepping motor 77. A gap 76 (see FIG. 3) having a predetermined size is formed between the developing roller peripheral surface 61A and the magnetic roller peripheral surface 62A. For example, the gap 76 is set to about 130 μm. The developing roller 61 is disposed so as to face the photosensitive drum 31 through an opening formed in the housing 60. A gap (eg, about 110 μm) having a predetermined size is also formed between the circumferential surface of the developing roller 61A and the circumferential surface of the photosensitive drum 31.

  The toner concentration sensor 67 detects the concentration of toner contained in the developer stored in the developer storage section 63A via the detection surface 68. Specifically, the toner concentration sensor 67 measures the magnetic permeability of the developer via the detection surface 68 and outputs a voltage corresponding to the magnetic permeability to the control unit 5 as an output signal (voltage signal). When the toner is consumed by the development, the ratio (ratio) of the toner in the developer changes, thereby changing the magnetic permeability of the developer. For example, when the toner ratio in the developer decreases, the magnetic permeability of the developer increases and the voltage level of the output signal also increases. The toner concentration sensor 67 outputs an output signal corresponding to the detected magnetic permeability to the control unit 5. The controller 5 determines the toner density of the developer based on the input output signal. As described above, the control unit 5 detects the toner density by detecting the magnetic permeability of the developer containing toner by the toner density sensor 67. The toner density sensor 67 may be a sensor board that incorporates a control board for determining the toner density.

  The toner density varies depending on the remaining amount of toner. Therefore, the control unit 5 can detect the remaining amount of toner contained in the developer in the developer storage unit 63A by detecting the toner density. That is, the control unit 5 acquires an output signal indicating the toner concentration (permeability) of the developer detected by the toner concentration sensor 67, and detects the remaining amount of the developer toner based on the toner concentration. Further, when the remaining amount of the detected toner becomes smaller than a predetermined amount, the control unit 5 slides the shutter 69 to open the supply port 70 and supplies the toner from the toner container 39 to the developing device 34. As described above, the control unit 5 keeps the concentration of the toner contained in the developer in the developing device 34 within a certain range.

  As shown in FIGS. 3 and 6, the toner concentration sensor 67 includes a casing 67A having a flat upper surface. A sensor body 67B capable of detecting the magnetic permeability of the developer is provided in the casing 67A. In the present embodiment, an opening penetrating the bottom wall is formed in the bottom surface of the developer storage chamber 63A, and a casing 67A is fitted into this opening. Thereby, the flat surface of the upper surface of the casing 67A is disposed inside from the bottom surface of the developer storage chamber 63A, and is provided on the bottom surface of the developer storage chamber 63A as the detection surface 68 described above.

  As shown in FIGS. 4 and 6, the scraper 66 moves in the rotation direction inside the developer storage chamber 63A as the screw feeder 64A rotates. When the screw feeder 64A rotates, the tip end portion (the end portion in the protruding direction) of the scraper 66 moves away from the inner wall of the developer storage chamber 63A in the cylindrical sectional view of the developer storage chamber 63A ( (See FIG. 8A). On the other hand, when the tip of the scraper 66 passes through the detection surface 68, the contact surface 66A of the scraper 66 moves while contacting the detection surface 68 and sliding (see FIGS. 6 and 8B). As a result, the scraper 66 removes the developer attached to the detection surface 68.

  Hereinafter, with reference to FIGS. 7 and 8, the operation of the scraper 66 and the signal waveform of the output signal output from the toner density sensor 67 will be described. As described above, the screw feeder 64A is rotated in the forward rotation direction by the stepping motor 77 during development. The screw feeder 64A conveys the developer in one direction while stirring the developer inside the developer storage chamber 63A. In the present embodiment, the stepping motor 77 is driven to rotate in the forward rotation direction at a constant speed. Therefore, as shown in FIG. 8, the scraper 66 moves (rotates) around the screw feeder 64 </ b> A in the rotation direction (forward rotation direction) as the screw feeder 64 </ b> A rotates. The scraper 66 contacts the detection surface 68 every time it rotates around the screw feeder 64A. In other words, the scraper 66 periodically contacts the detection surface 68 with a period of one rotation around the screw feeder 64A as one period. As a result, the developer staying on the detection surface 68 is scraped out in the positive rotation direction every time the scraper 66 makes one rotation.

  In the present embodiment, the developer on the detection surface 68 becomes the minimum amount immediately after being scraped by the scraper 66 (see FIG. 8A). On the other hand, the developer on the detection surface 68 gradually increases immediately after being scraped by the scraper 66, and reaches the maximum amount immediately before being scraped by the scraper 66 (see FIG. 8C). This is because the developer is gradually conveyed to the detection surface 68 by the screw feeder 64A immediately after being scraped out by the scraper 66, and the developer is gradually pressed against the detection surface 68 by the scraper 66, and the development on the detection surface 68 is performed. It is because the agent increases.

  As described above, since the amount of the developer on the detection surface 68 varies periodically, the output waveform of the output signal of the toner concentration sensor 67 is also the developer on the detection surface 68 as shown by the waveform 82 in FIG. It fluctuates periodically according to the amount of. Here, a waveform 82 in FIG. 7 shows an output waveform of the toner concentration sensor 67 when the usable developing device 34 is attached to the image forming unit 3. According to the waveform 82, as shown in FIG. 7, when the developer on the detection surface 68 reaches the minimum amount at time T01, the output signal of the toner density sensor 67 becomes the minimum value at the same timing (time T01). Become. The developer on the detection surface 68 gradually increases until time T04 and reaches the maximum amount at time T04, and the output signal of the toner density sensor 67 reaches the maximum value at the same timing (time T04). Thereafter, the developer is scraped off by the scraper 66, so that the developer becomes the minimum amount again at the time T05, and the signal waveform also becomes the minimum value. The period T40 of this waveform 82 (the time from time T01 to time T05) is also the time required for one rotation of the scraper 66. In the present embodiment, period information indicating the period T40 obtained when the developing device 34 that can be used in the image forming unit 3 is mounted is stored in the ROM 52 in advance.

  On the other hand, the output waveform of the toner density sensor 67 when the incompatible developing device (for example, equipped with the gear 78 having a different transmission ratio to the developing roller 61 of the developing device 34) that cannot be normally used in the image forming unit 3 is mounted. Also fluctuate periodically. Here, a waveform 83 in FIG. 7 shows an output waveform of the toner concentration sensor 67 when the incompatible developing device is attached to the image forming unit 3. When the stepping motor 77 is rotationally driven at a constant speed, if the transmission ratio of the rotational driving force is different, the rotational speed of the developing roller 61 is also different, and the scraper 66 moves (rotates) as the screw feeder 64A rotates. The speed is also different. Therefore, a waveform 83 having a period different from that of the waveform 82 is obtained as the output waveform of the toner concentration sensor 67. According to this waveform 83, as shown in FIG. 7, when the developer on the detection surface 68 reaches the minimum amount at time T01, the output signal of the toner density sensor 67 is the minimum value at the same timing (time T01). It becomes. The developer on the detection surface 68 gradually increases until time T02 and reaches the maximum amount at time T02 earlier than time T04. At the same timing (time T02), the output signal of the toner density sensor 67 reaches the maximum value. Become. Thereafter, the developer is scraped off by the scraper 66, so that the developer becomes the minimum amount again at the time T03, and the signal waveform also becomes the minimum value. The period T30 (time from time T01 to time T03) of the waveform 83 is also the time required for the scraper 66 in the incompatible developing device to make one rotation.

  In the present embodiment, in a plurality of developing devices that can be attached to the image forming unit 3, as described above, the period of the signal waveform output from the toner density sensor 67 is different for each developing device, which will be described later. Identification processing is executed by the control unit 5. As a result, the developing device mounted on the image forming unit 3 can be accurately identified.

<Identification process>
Hereinafter, with reference to FIG. 9, a procedure of identification processing of the developing device 34 executed by the control unit 5 will be described. In the flowchart of FIG. 9, steps S1, S2,... Represent processing procedure (step) numbers. In the present embodiment, when the control unit 5 executes the identification process, the developing device 34 causes the image forming unit 3 based on the period of the signal waveform output from the toner density sensor 67 while the scraper 66 is rotated by the stepping motor 77. To determine if it can be used. The control unit 5 when executing the identification processing corresponds to the control means according to the present invention. In the following description, among developing devices that can be mounted on the image forming unit 3, a usable device that is compatible with the image forming unit 3 is referred to as a developing device 34, and an incompatible device that cannot be normally used in the image forming unit 3. The incompatible developing device is used. For convenience of explanation, the components of the incompatible developing device will also be described with reference numerals of the components of the developing device 34.

  In step S1, the control unit 5 determines whether the image forming apparatus 100 is activated. For example, when the power of the image forming apparatus 100 is turned on, the image forming apparatus 100 is activated when the replacement of the developing device 34 in the image forming apparatus 100 is finished and the normal operation state (normal operation mode) is restored. judge. If it is determined that the image forming apparatus 100 is activated, the control unit 100 drives the stepping motor 77 to rotate in the normal rotation direction (S2). As a result, the developing roller 61, the magnetic roller 62, the screw feeder 64A, and the screw feeder 64B are rotated in the forward rotation direction. Further, as the screw feeder 64A rotates, the scraper 66 moves around the screw feeder 64A. Move (rotate) in the direction of rotation.

  Next, in step S <b> 3, the control unit 5 starts measuring the output signal of the toner density sensor 67. Specifically, the output signal (voltage signal) output from the toner density sensor 67 is sampled and measured with time, and stored in the RAM 53. As a result, output waveform data (output signal waveform data) as shown in FIG. 7 is stored in the RAM 53. The output signal is measured until a predetermined sampling time elapses (S4). Here, the sampling time is the time required for the scraper 66 to make one rotation around the screw feeder 64A in the positive rotation direction when the suitable developing device 34 is mounted (period T40, see FIG. 7). Of course, the sampling time may be equal to or longer than the period T40, but in order to minimize the processing time, it is preferable to set the period T40 when the suitable developing device 34 is mounted as the sampling time.

  Next, in step S <b> 5, the control unit 5 calculates the cycle Ts of the waveform data based on the waveform data stored in the RAM 53. Specifically, the time from the minimum value to the maximum value in the waveform data is counted, and the time is defined as a cycle Ts. For example, when the sampling time is sufficiently long, an average value of a plurality of periods obtained from the waveform data can be calculated, and the average value can be set as the period Ts.

  In step S6, the control unit 5 determines whether or not a calculation error of the cycle Ts has occurred. Specifically, it is determined whether or not the cycle Ts can be calculated in step S5. For example, if the mounted developing device does not have mounting compatibility and the rotational driving force of the stepping motor 77 cannot be transmitted correctly, the scraper 66 does not rotate, and therefore the period Ts cannot be obtained. In this case, the control unit 5 determines that the calculation error has occurred. If it is determined in step S5 that the cycle Ts is not obtained and it is a calculation error, in the next step S9, the control unit 5 outputs an error message to the operation display unit 6 to display the error message. Examples of error messages include a message indicating that a developing device with incompatible mounting is installed, a message indicating that a non-genuine developing device is installed, and a type of developing device that can be mounted A message indicating that the developing device is to be replaced is considered together with the number.

  If it is determined in step S6 that there is no calculation error, in the next step S7, the control unit 5 compares the calculated period Ts with the period information (threshold value) stored in the ROM 52, and is attached. It is determined whether or not the developing device can be used in the image forming unit 3. Specifically, the control unit 5 determines whether the cycle Ts matches the cycle information. Here, as described above, the cycle information is information indicating the cycle of the scraper 66 of the developing device 34 suitable for the image forming unit 3. Therefore, when the period Ts matches the period information, this means that the developing device 34 that can be used in the image forming unit 3 is attached to the image forming unit 3. For this reason, when it is determined in step S7 that the cycle Ts and the cycle information match, the control unit 5 completes preparation for development processing and image formation processing in the operation display unit 6 in the next step S8. A ready message indicating that this is output and displayed. On the other hand, if the period Ts does not match the period information, this means that an incompatible developing device that cannot be used in the image forming unit 3 is mounted on the image forming unit 3. For this reason, when it is determined in step S7 that the period Ts does not match the period information, the control unit 5 outputs an error message to the operation display unit 6 for display in the next step S9. Examples of error messages at this time include a message indicating that an incompatible developing device is installed, a message indicating that a non-genuine developing device is installed, and a type of developing device that can be mounted A message or the like indicating that the developing device is to be replaced together with the number.

<Effect of embodiment>
In the above-described embodiment, each process is executed by the control unit 5 in accordance with the procedure of steps S2 to S7, thereby determining whether or not the mounted developing device can be used. That is, the control unit 5 can identify whether the mounted developing device can be used in the image forming unit 3 or cannot be used. This identification is performed based on the period of the waveform of the output signal of the toner density sensor 67 provided in the developing device. For this reason, it is possible to identify the developing device with a simple configuration without mounting a storage unit such as a memory for holding identification determination information in the developing device. Further, since the toner density sensor 67 provided for detecting the developer density or the like is used, the developing device can be identified without providing a new detection means.

<Modification of Embodiment>
In the above description of the embodiment, the example in which the developing device 34 is identified based on the period of the output waveform of the toner density sensor 67 included in the developing device 34 has been described, but the present invention is not limited to this. For example, another sensor having the same configuration as that of the toner density sensor 67 without using the existing toner density sensor 67 is provided, and a sensor capable of detecting the magnetic permeability of the developer is provided. The developing device may be identified by obtaining the period. In the above-described embodiment, the developing device 34 using a two-component developer has been described as an example, but of course, the image forming apparatus 100 including a developing device using a one-component developer is also used. The present invention is applicable.

  Since the scope of the present invention is defined by the appended claims rather than by the detailed description preceding the claims, the embodiments described herein are exemplary only and not limiting. I want to be understood. Therefore, all the modifications which do not deviate from a claim, or an equivalent are included in a claim.

100: image forming apparatus 3: image forming unit 5: control unit 31: photosensitive drum 34: developing device 39: toner container 52: ROM
60: Housing 61: Developing roller 62: Magnetic roller 63: Developer storing unit 63A, 63B: Developer storing chamber 64A, 64B: Screw feeder 66: Scraper 67: Toner concentration sensor 68: Detection surface 77: Stepping motor 78: Gear 79: Supporting part 101: Shaft-shaped member 102: Outer fitting part 103, 104: Engagement piece 110: Extension part

Claims (5)

An image forming apparatus that performs development processing using a mounted developing device,
The developing device includes:
A developer container containing a developer and having a detection surface inside;
Detection means for detecting the magnetic permeability of the developer in the developer container via the detection surface;
A contact member that periodically contacts the detection surface by being rotated in the developer container;
Drive transmission means for transmitting a rotational driving force to the contact member;
The image forming apparatus includes:
Drive means for supplying rotational drive force to the drive transmission means of the mounted developing device;
An image forming apparatus comprising: a control unit that determines whether or not the developing device can be used based on a period of a signal waveform output from the detection unit during rotation of the contact member by the driving unit. A storage unit for storing period information regarding the period corresponding to a developing device usable in the image forming apparatus;
2. The control unit according to claim 1, wherein the control unit determines whether the developing device can be used by comparing a cycle of a signal waveform output from the detection unit with cycle information stored in the storage unit. Image forming apparatus. The period information is a natural period of the developing device obtained based on a transmission ratio of the drive transmission unit of the developing device usable in the image forming apparatus,
The control unit determines that the developing device can be used when a cycle of a signal waveform output from the detection unit matches a cycle information stored in the storage unit. Image forming apparatus. The developing device further includes a stirring unit that stirs the developer by being rotated in the developing container,
The contact member is attached to the stirring means, and contacts the detection surface by moving in the rotation direction as the stirring means rotates,
The image forming apparatus according to claim 1, wherein the drive transmission unit transmits a rotational driving force to the contact member via the stirring unit. The stirring means has a support portion that protrudes in a direction perpendicular to the rotation center axis of the stirring means,
The image forming apparatus according to claim 4, wherein the contact member is a flexible plate-like member having an end portion joined to the support portion and extending in the vertical direction.

Images