JP2019090865A - Image forming apparatus - Google Patents

Abstract

To achieve reduction in size and cost of a developing device when a toner concentration sensor is required to detect the concentration of toner in a developer in a developing container.SOLUTION: A toner concentration sensor 45 for detecting the concentration of toner in a developer in a developing container 41 is disposed in an apparatus body (frame body 100a). The toner concentration sensor 45 is loosely fit to a loose fitting part 60 provided with a pressing spring 61. The pressing spring 61 moves the toner concentration sensor 45 to a contact surface 41b in association with an operation to attach a developing device 4, and after completion of attachment of the developing device 4, presses the toner concentration sensor 45 against the contact surface 41b. The toner concentration sensor 45 is regulated from moving by a first guide 80a and a second guide 80b of a guide part 80, and is thereby stably and reliably brought into contact with the contact surface 41b. The provision of the toner concentration sensor 45 in the apparatus body in this way can achieve reduction in size and cost of the developing device 4.SELECTED DRAWING: Figure 5

Description

  The present invention relates to an image forming apparatus using an electrophotographic technology such as a printer, a copier, a facsimile machine, or a multifunction machine.

  In the image forming apparatus, a developing device for developing the electrostatic latent image formed on the photosensitive drum with a developer to visualize the electrostatic latent image is detachably provided in the apparatus main body. In the developing device, a two-component developer (hereinafter, simply referred to as a developer) composed of nonmagnetic toner and magnetic carrier is accommodated in a developing container, and this developer is used for development. Then, while the toner is consumed by being provided for development, the carrier is repeatedly used without being consumed. Therefore, when the same developer is used repeatedly over a long period, the toner concentration of the developer (the ratio of the weight of toner (T) to the total weight of toner and carrier (D): TD ratio) gradually decreases. However, the developer whose toner concentration is too low tends to cause image defects. Therefore, control is appropriately performed to adjust the toner concentration by appropriately replenishing the developing device with toner so that the toner concentration of the developer does not fall below the appropriate range in which an appropriate image can be formed. Conventionally, in order to detect the toner concentration of the developer in the developing container, a toner concentration sensor is provided in the developing device (Patent Document 1, Patent Document 2).

Unexamined-Japanese-Patent No. 11-7189 JP-A-11-352764

  As described above, conventionally, the toner concentration sensor is disposed in the developing device which is attachable to and detachable from the apparatus main body. In this case, in addition to the toner concentration sensor, various components such as a signal line for transmitting the detection result (electrical signal) of the toner concentration sensor, a relay connector of the signal line, a signal line guide and the like are mounted on the developing device. Therefore, it is necessary to secure a space for arranging these in the developing device, which inevitably enlarges the developing device, which is contrary to the recent demand for miniaturization. Further, since the developing device is a replacement part that needs to be replaced regularly, it is desirable to reduce the cost as much as possible. However, conventionally, even though the toner concentration sensor (also the above-mentioned signal line, relay connector, signal line guide, etc.) is replaced together, although it is still usable together with the developing device, It was difficult to realize the cost reduction of the developing device.

  The present invention has been made in view of the above problems, and has a toner concentration sensor for detecting the toner concentration of the developer contained in the developing container, thereby reducing the size and cost of the developing device as a replacement part. To provide an image forming apparatus capable of realizing the above.

  The image forming apparatus according to the present invention has an apparatus main body, a photosensitive member on which an electrostatic latent image is formed, and a developing container detachably mounted on the apparatus main body and containing a developer including toner and a carrier. A developing device for developing an electrostatic latent image formed on the photosensitive member into a toner image by the developer contained in the developing container, and the developing device being disposed in contact with the contact surface of the developing container A detection unit capable of detecting the toner concentration of the developer contained in the developer container, the detection unit being associated with the mounting operation in which the developing device is mounted at a predetermined position of the apparatus main body It is characterized in that it is in contact with the contact surface.

  According to the present invention, the detecting means for detecting the toner concentration of the developer contained in the developing container is disposed not in the developing device but in the device main body, so that the size and cost of the developing device detachable from the device main body can be reduced. Down can be realized.

FIG. 1 is a schematic view showing a configuration of an image forming apparatus of the present embodiment. FIG. 2 is a cross-sectional view showing the developing device of the present embodiment. FIG. 2 is a top cross-sectional view showing the developing device as viewed in a horizontal cross section including an axial direction. FIG. 2 is a perspective view showing the image forming apparatus of the first embodiment, where (a) is before the completion of mounting of the developing device, (b) is after the mounting of the developing device, and (c) is after accommodation in the housing. FIG. 2 is an enlarged perspective view showing the vicinity of a toner concentration sensor in the first embodiment. FIG. 8A is a perspective view showing the developing device, and FIG. 8B is an enlarged perspective view showing the vicinity of the toner concentration sensor. FIG. 7A is a perspective view showing the developing device, and FIG. 7B is an enlarged perspective view showing the vicinity of a toner concentration sensor, after the mounting of the developing device in the second embodiment is completed.

First Embodiment
<Image forming apparatus>
The first embodiment will be described. First, a schematic configuration of the image forming apparatus according to the present embodiment will be described with reference to FIG. An image forming apparatus 100 shown in FIG. 1 is a full-color printer of a tandem type intermediate transfer system in which image forming units Sa, Sb, Sc, and Sd are arranged along an intermediate transfer belt 7.

  In the image forming unit Sa, a yellow toner image is formed on the photosensitive drum 1 a and transferred to the intermediate transfer belt 7. In the image forming portion Sb, a magenta toner image is formed on the photosensitive drum 1 b and transferred to the intermediate transfer belt 7. In the image forming units Sc and Sd, cyan toner images and black toner images are formed on the photosensitive drums 1c and 1d, respectively, and are transferred to the intermediate transfer belt 7. The four color toner images transferred to the intermediate transfer belt 7 are conveyed to the secondary transfer portion T2 and secondarily transferred to the recording material P (paper, sheet material such as OHP sheet, etc.).

  The image forming portions Sa, Sb, Sc, and Sd are configured in substantially the same manner except that the colors of toners used in the developing devices 4a, 4b, 4c, and 4d are different from yellow, magenta, cyan, and black. Hereinafter, the configurations and operations of the image forming units Sa to Sd will be described by omitting a, b, c, and d at the end of the reference numerals indicating the distinction between the image forming units Sa, Sb, Sc, and Sd.

  In the image forming portion S, a primary charger 2, an exposure device 3, a developing device 4, a primary transfer roller 5, and a secondary charger 6 are disposed so as to surround the photosensitive drum 1 as a photosensitive member. The photosensitive drum 1 is a cylindrical (drum-shaped) aluminum cylinder on the outer peripheral surface of which a photosensitive layer, which is an organic photosemiconductor with a negative charge characteristic, is formed. Is rotated in the direction of arrow R1. The photosensitive drum 1 is formed to have, for example, a diameter of 30 mm and a length in the rotation axis direction (longitudinal direction) of 360 mm.

  The primary charger 2 is, for example, a charging roller formed in a roller shape, and a charging voltage is applied from a high voltage power supply (not shown) to contact the photosensitive drum 1 to uniformly darken the photosensitive drum 1 in negative polarity. Charge to potential. The charging roller as the primary charger 2 is urged toward the photosensitive drum 1 by a pressure spring (not shown), and therefore, is driven to rotate by the photosensitive drum 1. As a charging voltage applied to the charging roller, for example, a superimposed voltage in which an AC voltage of peak voltage 1500 V is superimposed on a DC voltage of −900 V is applied. The charging roller is formed to have, for example, a diameter of 14 mm and a length of 320 mm in the rotation axis direction (longitudinal direction).

  The exposure device 3 generates, from a laser light emitting element, a laser beam obtained by ON-OFF modulating scanning line image data obtained by developing separated color images of respective colors, and scanning this with a rotating mirror to charge the surface of the photosensitive drum 1. It is a laser beam scanner that writes an electrostatic latent image of an image. The secondary charger 6 disposed upstream of the primary charger 2 in the rotational direction of the photosensitive drum 1 is a charging assisting device that assists the charging of the primary charging device 2. The developing device 4 supplies toner to the photosensitive drum 1 to develop the electrostatic latent image into a toner image. In the case of the present embodiment, the developing device 4 is detachably provided in the apparatus main body. The developing device 4 will be described later (FIGS. 2 and 3).

  The primary transfer roller 5 is disposed opposite to the photosensitive drum 1 with the intermediate transfer belt 7 interposed therebetween, and forms a primary transfer portion (primary transfer nip portion) T1 of the toner image between the photosensitive drum 1 and the intermediate transfer belt 7. At the primary transfer portion T1, a primary transfer voltage is applied to the primary transfer roller 5 by a high voltage power supply (not shown), whereby the toner image is primarily transferred from the photosensitive drum 1 to the intermediate transfer belt 7.

  The intermediate transfer belt 7 is supported by being supported by the secondary transfer inner roller 8 and tension rollers 17 and 18, etc., and is driven by the secondary transfer inner roller 8 also serving as a driving roller to rotate in the direction of arrow R2 in FIG. Be done. The intermediate transfer belt 7 is rotated at substantially the same speed as the rotational speed (process speed) of the photosensitive drum 1. The secondary transfer portion T2 is a toner image transfer nip on the recording material P formed by bringing the secondary transfer outer roller 9 into contact with the intermediate transfer belt 7 supported by the secondary transfer inner roller 8. At the secondary transfer portion T2, a secondary transfer voltage is applied to the secondary transfer outer roller 9, whereby the toner image is secondarily transferred onto the recording material P conveyed from the intermediate transfer belt 7 to the secondary transfer portion T2. Ru. The recording material P is stored in a state of being stacked on the sheet feeding cassette 10, and is conveyed from the sheet feeding cassette 10 to the secondary transfer portion T2 by a sheet feeding roller, a conveyance roller, a registration roller, etc. not shown.

  The secondary transfer residual toner remaining on the intermediate transfer belt 7 after the secondary transfer is removed by the belt cleaning device 11 rubbing the intermediate transfer belt 7. The belt cleaning device 11 rubs the cleaning blade on the intermediate transfer belt 7 to remove secondary transfer residual toner.

  The recording material P on which the four color toner images have been secondarily transferred at the secondary transfer portion T 2 is conveyed to the fixing device 13. In the fixing device 13, the fixing rollers 14 and 15 are in contact with each other to form a fixing nip T <b> 3, and the toner image is fixed to the recording material P while conveying the recording material P at the fixing nip T <b> 3. In the fixing device 13, the fixing roller T5 is formed by pressing the fixing roller 15 against the fixing roller 14 which is internally heated by a lamp heater or the like (not shown) by an urging mechanism (not shown). The recording material P is heated and pressed by being nipped and conveyed by the fixing nip T3, and the toner image is fixed on the recording material P. The recording material P on which the toner image is fixed by the fixing device 13 is discharged out of the machine body.

<Developer>
The developing device 4 will be described with reference to FIGS. 2 and 3. As shown in FIG. 2, the developing device 4 includes a developing container 41 forming a housing, a regulating blade 42, a developing sleeve 30, a developing screw 31, a stirring screw 32, and the like.

  The developing container 41 contains a two-component developer containing nonmagnetic toner and magnetic carrier. That is, in this embodiment, a two-component developing method is used as a developing method, and a nonmagnetic toner of negative charging polarity and a magnetic carrier of positive charging polarity are mixed and used as a developer. The nonmagnetic toner is obtained by incorporating a colorant, an external additive such as colloidal silica fine powder, and a wax into a resin such as polyester and styrene acrylic, and pulverizing or polymerizing it. The magnetic carrier is obtained by applying a resin coating to the surface layer of a core made of resin particles obtained by mixing and kneading ferrite particles and magnetic powder. The toner concentration (the ratio of the weight of the toner to the total weight of the developer, the TD ratio) of the developer in the initial state is, for example, 8%.

  The developing container 41 is partially opened at the opposite side of the photosensitive drum 1, and the developing sleeve 30 is rotatably disposed so that a part is exposed at the opening. The developing sleeve 30 can be disposed close to the photosensitive drum 1 with a predetermined gap (SD gap) therebetween. The closest distance between the developing sleeve 30 and the photosensitive drum 1, that is, the distance of the SD gap is kept at, for example, 260 μm along the rotation axis direction. In the present embodiment, an area where the photosensitive drum 1 and the developing sleeve 30 face each other via the SD gap is referred to as an SD gap portion (developing area). The developing sleeve 30 is rotationally driven to move in the direction opposite to the rotational direction (the direction of the arrow R1) of the photosensitive drum 1 in the SD gap portion (the direction of the arrow R3). That is, in the present embodiment, a counter development method is adopted. The developing sleeve 30 is formed in a cylindrical shape from a nonmagnetic material such as aluminum or stainless steel, and is rotationally driven at a predetermined process speed (for example, 250 mm / sec). The developing sleeve 30 has, for example, a diameter of 20 mm and a length in the rotational axis direction (longitudinal direction) of 334 mm.

  Inside the developing sleeve 30, a magnet roller 30a constituted by a plurality of magnetic poles is disposed non-rotatably. A magnetic spike of a developer (also referred to as a magnetic brush) is formed on the surface of the developing sleeve 30 by the magnetic force of the plurality of magnets (N1, N2, N3, S1, S2) disposed in the magnet roller 30a. The thickness of the magnetic brush formed on the surface of the developing sleeve 30 is regulated by a plate-shaped regulating blade 42 made of a nonmagnetic material. The restriction blade 42 is adjusted in the gap with the surface of the developing sleeve 30. The developing sleeve 30 rotates in the direction of arrow R3 while supporting the developer whose layer thickness is regulated by the regulating blade 42, and the photosensitive drum 1 is rubbed with a magnetic brush in the SD gap portion to make the developer Supply. A developing bias voltage in which a DC voltage and an AC voltage are superimposed is applied to the developing sleeve 30 from a high voltage power supply (not shown). As a result, toner is supplied to the electrostatic image formed on the photosensitive drum 1, and the electrostatic image is developed into a toner image.

  As shown in FIG. 2, the developing container 41 is formed with a developing chamber 21 as a first chamber and a stirring chamber 22 as a second chamber, and between the developing chamber 21 and the stirring chamber 22, the developing chamber 21 and A partition 70 is provided to separate from the stirring chamber 22. The partition wall 70 separates the developing chamber 21 and the agitating chamber 22 so as to protrude from the bottom surface portion 41 a into the developing container 41 (in the developing container). The partition 70 extends in the rotational axis direction (longitudinal direction) of the developing sleeve 30. In the present embodiment, the developing device 4 in which the dividing wall 70 is provided so that the developing chamber 21 and the agitating chamber 22 are substantially aligned in the horizontal direction is described as an example (a so-called horizontal stirring type). . For example, the developing device 4 may be a developing device 4 in which the dividing wall 70 is provided in a substantially horizontal direction parallel to the bottom surface portion 41 a so that the developing chamber 21 and the agitating chamber 22 are vertically aligned. Type).

  As shown in FIG. 3, the partition wall 70 has a first communicating portion 23 and a second communicating portion 24 that respectively connect the developing chamber 21 and the stirring chamber 22 on both end sides in the longitudinal direction. In the case of the present embodiment, both ends of the partition wall 70 do not reach the side walls of both end portions in the longitudinal direction of the inside of the developing container 41, whereby the first communicating portion 23 and the second communicating portion 24 are formed. . The first communicating portion 23 is a path through which the developer is transferred from the stirring chamber 22 to the developing chamber 21, and the second communicating portion 24 is a path through which the developer is transferred from the developing chamber 21 to the stirring chamber 22.

  In the developing chamber 21, a developing screw 31 for conveying the developer in a predetermined first direction in the developing chamber 21 is disposed. In the stirring chamber 22, a stirring screw 32 for conveying the developer in a second direction opposite to the developer conveyance direction (first direction) of the developing screw 31 in the stirring chamber 22 is disposed. In the developing screw 31 and the stirring screw 32, blades 31b and 32b are formed spirally around the rotation shafts 31a and 32a, respectively. Both end portions of the rotating shafts 31 a and 32 a are rotatably supported with respect to the developing container 41.

  The developing sleeve 30, the developing screw 31, and the stirring screw 32 are connected and driven by, for example, a gear train (not shown), and rotate through a gear train from a driving motor (not shown). The developer is circulated and transported in the developing container 41 by the rotation of the developing screw 31 and the stirring screw 32. At this time, with respect to the developer conveying direction (second direction) of the agitating screw 32, the developer is transferred from the agitating chamber 22 to the developing chamber 21 at the first communicating portion 23 downstream in the second direction. The developer is delivered from the developing chamber 21 to the agitating chamber 22 at the second communicating portion 24. Thus, the developing chamber 21 and the agitating chamber 22 form a circulation path of the developer, and the developer is mixed and stirred by circulating through the circulation path.

  In the case of the present embodiment, as shown in FIG. 2, the developing container 41 is formed with an abutting surface 41 b and a guiding surface 41 c on the outer surface thereof. Here, the contact surface 41b and the guide surface 41c are continuously formed in the developing container 41 so that the contact surface 41b is positioned on the upper side in the vertical direction of the guide surface 41c. The guide surface 41 c is formed in a curved or inclined shape from the bottom surface portion 41 a of the developer container 41 to the contact surface 41 b. The guide surface 41c slides on the toner concentration sensor 45 (see FIG. 4A described later) disposed in the apparatus main body with the mounting operation of the developing device 4, and on the developing container 41 side (developing container side) The toner concentration sensor 45 biased in the facing direction can be moved in the direction opposite to the biasing direction.

  The toner density sensor 45 disposed in the apparatus main body is in contact with the contact surface 41b in response to the development device 4 being mounted at a predetermined position in the apparatus main body. In this embodiment, in order to detect the toner concentration of the developer in the developing container 41 from the outer surface side of the developing container 41, as a detecting means, it is possible to detect the toner concentration without directly touching the sensor detection surface with the developer. A contact type toner concentration sensor 45 is employed.

  The contact surface 41b has a height at which the toner concentration sensor 45 can detect the toner concentration of the developer in the developing container 41, and more specifically, in the vertical direction than the height of the developer being conveyed in the developing container 41. It is formed at a low height position. The thickness of the developing container 41 on the contact surface 41 b is preferably thinner than other portions such as the guiding surface 41 c so that the toner concentration sensor 45 can detect the toner concentration of the developer in the developing container 41. In order to do so, the contact surface 41b may have, for example, a groove recessed toward the inner side of the developing container 41 than the guide surface 41c, and the toner density sensor 45 may be fitted in the groove.

  Further, as shown in FIGS. 2 and 3, the toner concentration sensor 45 is placed on the outer surface of the developing container 41 in order to ensure that the toner concentration sensor 45 abuts on the abutment surface 41 b with the mounting operation of the developing device 4. The guide part 80 as a detection guide part which guides to the contact surface 41b is provided. The guide portion 80 will be described later (see FIG. 5).

<Supply and discharge of developer>
By the way, in the case of the developing device 4 which performs development using a two-component developer, toner is consumed by development, so the toner concentration of the developer stored in the developing container 41 is in an appropriate range (for example, 6 to 9%) Below the lower limit of When a developer whose toner concentration is lowered and deviates from the appropriate range is used, an image defect tends to occur. Therefore, in order to recover the toner concentration to an appropriate range, a replenishing developer (replenishing agent) in which, for example, the toner and the carrier are mixed at a weight ratio of 9: 1 from a replenishing device (not shown) connected to the developing device 4 Is controlled to recover the toner concentration.

  As shown in FIG. 3, in the developing container 41, on the upstream side of the second communicating portion 24 of the stirring chamber 22 in the second direction, a replenishing portion 51 for receiving the replenishing agent from the replenishing device is formed. The replenishing agent is replenished by the replenishing device. However, if the amount of the developer in the developing container 41 becomes excessive with the replenishment of the replenishing agent, the agitation of the developer is insufficient and an image defect is likely to occur. Therefore, the developer discharge portion 50 of the developing container 41 is, for example, more than the first communicating portion 23 of the agitating chamber 22 so that the surplus developer is discharged from the developing container 41 with the replenishment of the replenishment agent. It is formed on the second direction downstream side.

  In order to perform the above-described control for recovering the toner concentration, it is necessary to detect the toner concentration of the developer in the developing container 41. For that purpose, the toner concentration sensor 45 is used. In the image forming apparatus 100 of the present embodiment, unlike the conventional case where the toner concentration sensor 45 is disposed in the developing device 4, the non-contact type toner concentration sensor 45 is disposed in the main body of the apparatus. However, when the non-contact type toner concentration sensor 45 is disposed in the apparatus main body, the toner concentration sensor 45 needs to be in contact with the developing container 41 in order to detect the toner concentration with high accuracy. Therefore, in the present embodiment, the toner concentration sensor 45 is brought into contact with the contact surface 41 b formed on the developing container 41 along with the mounting operation of the developing device 4 so that the toner concentration of the developer is detected by the toner concentration sensor 45. It is possible. In order to bring the toner concentration sensor 45 into contact with the contact surface 41 b, a guide portion 80 for guiding the toner concentration sensor 45 is provided in the developing container 41. Hereinafter, the details of the first embodiment will be described with reference to FIGS. 4A to 5. In order to facilitate understanding of the description, in FIGS. 4A to 4C, illustration of a part of the apparatus main body (such as a side plate) is omitted.

  As shown in FIG. 4A, the image forming apparatus 100 is provided so as to be horizontally insertable into and removable from the housing, and the plurality of developing devices 4a to 4d are individually attached and detached when the image forming apparatus 100 is pulled out from the housing. It has a possible frame 100a. The frame 100a separates the developing devices 4a to 4d by being pulled out of the case when the cover 300 movable to the open position where the front surface of the image forming apparatus 100 is opened and the shielded position that is shielded is in the open position. In the mounting direction F, the installation direction is from the upper side to the lower side in the vertical direction. In the present embodiment, as shown in FIGS. 4A and 4B, the operation of mounting the developing devices 4a to 4d on the frame 100a corresponds to the mounting operation of the developing device. When mounted, the developing devices 4a to 4d are mounted at the mounting position (predetermined position) of the frame 100a while sliding the toner concentration sensor 45 on the above-described guide surface 41c.

  In order to detect the toner concentration of the developer in each of the developing devices 4a to 4d (specifically, in the developing container), the developing devices 4a to 4d can be mounted on the frame 100a which is a part of the apparatus main body A toner concentration sensor 45 is disposed at each mounting position. The toner density sensor 45 is loosely fitted in the loose fitting portion 60, and as shown in FIG. 4B, the loose fitting portion 60 is held by the guide portion 80 along with the mounting operation of the developing devices 4a to 4d. Thus, the toner density sensor 45 can contact the contact surface 41b (see FIG. 2). Then, as shown in FIG. 4C, the cover 300 can be moved from the open position to the blocking position in a state in which the frame 100a is stored in the housing (the housing direction is the Y direction in the drawing). Even when the frame 100a is housed in the housing, the toner concentration sensor 45 is maintained in the state of being in contact with the contact surface 41b.

<Guide section>
FIG. 5 is an enlarged perspective view showing the vicinity of the toner density sensor 45 in a state of being in contact with the contact surface 41b. As shown in FIG. 5, the guide portion 80 is provided with a pair of first guides 80a erected at an interval so as to extend from the outer surface of the developer container 41 in the mounting direction F (see FIG. 4A); And a second guide 80b erected to extend in the horizontal direction (longitudinal direction). The first guide 80a and the second guide 80b are disposed around the abutment surface 41b so that the loose fitting portion 60 can enter.

  The toner density sensor 45 is loosely fitted to the loose fitting portion 60. Therefore, the position is not fixed with respect to the developing container 41 as it is, and the contact of the toner density sensor 45 with the contact surface 41b may become unstable. There is. If the contact is unstable, it may affect the detection of the toner concentration by the toner concentration sensor 45, and the detection accuracy may be reduced. In order to prevent this, the guide portion 80 guides the toner density sensor 45 loosely fitted to the loose fitting portion 60 to the contact surface 41b, and the toner density sensor 45 can be reliably contacted to the contact surface 41b Position in the right position. Specifically, after the mounting of the developing device 4 to the predetermined position is completed, the position in the substantially Y direction is determined by the first guide 80a, and the position in the substantially Z direction is determined by the second guide 80b. As a result, the movement of the toner concentration sensor 45 is restricted in combination with the pressure by the pressure spring 61, which will be described later, and the toner concentration sensor 45 is stably and reliably abutted against the contact surface 41b.

<Free fitting part>
The loose fitting portion 60 is provided with a moving mechanism 200 for moving the loosely fitted toner density sensor 45 to the contact surface 41 b in accordance with the mounting operation of the developing device 4. In the case of this embodiment, a pressing spring 61 is used for the moving mechanism 200. The pressing spring 61 as a biasing portion is, for example, a leaf spring or a coil spring, and biases the toner density sensor 45 loosely fitted in the loosely fitted portion 60 in the direction toward the developing container 41 side. Therefore, the toner density sensor 45 loosely fitted to the loosely fitted portion 60 is limited to the range restricted by the loosely fitted portion 60 until the mounting of the developing device 4 to the predetermined position is completed. Can move relatively freely. After the mounting of the developing device 4 to the predetermined position is completed, the toner density sensor 45 is pressed by the pressure spring 61 and abuts against the developing container 41, whereby the movement in the substantially X direction is restricted. Also, as described above, the movement in the substantially Y direction is restricted by the first guide 80a, and the movement in the substantially Z direction is restricted by the second guide 80b. Thus, the toner density sensor 45 is stably in contact with the contact surface 41b. Further, the toner concentration sensor 45 is pressed against the wall surface (the contact surface 41b) of the developing container 41 by the pressing spring 61, whereby the stability is increased and the detection accuracy of the toner concentration is further enhanced.

  As described above, in the present embodiment, the toner concentration sensor 45 for detecting the toner concentration of the developer in the developing container 41 is disposed in the apparatus main body. Then, the toner concentration sensor 45 is brought into contact with the developing container 41 (specifically, the contact surface 41b) with the mounting operation of the developing device 4 so that the toner concentration of the developer in the developing container 41 can be detected. By arranging the toner concentration sensor 45 in the main body of the apparatus, it is not necessary to secure a space for the toner concentration sensor 45 and the signal line and the like accompanying it in the developing device 4 in the developing device 4. Miniaturization can be realized. Further, when the developing device 4 is replaced, the toner density sensor 45 and the signal line accompanying it remain on the apparatus main body side, so it is easy to reuse them. That is, since the developing device 4 to be replaced does not include the toner density sensor 45 or the signal line, the cost reduction of the developing device 4 as a replacement part can be realized.

  In the case of this embodiment, the movement mechanism 200 is not limited to the use of the pressing spring 61. For example, as a resiliently projecting portion in which a part of the frame 100a is protruded to the developing container 41 side The density sensor 45 may be biased in the direction toward the developing container 41 side. The moving mechanism 200 may be any mechanism as long as it moves the toner density sensor 45 disposed in the apparatus main body to the contact surface 41 b in accordance with the mounting operation of the developing device 4.

  The contact surface 41b of the developing container 41 to be in contact with the toner concentration sensor 45 may be formed on the developing chamber 21 side instead of on the agitating chamber 22 side. Alternatively, a plurality of contact surfaces 41b may be formed, and the toner density sensor 45 may be in contact with each contact surface 41b. That is, the toner concentration sensor 45 is not limited to one, and may be plural, and may be disposed on either the stirring chamber 22 side or the developing chamber 21 side. The frame 100 a may be stored not only from the front of the image forming apparatus 100 but also from the side or back of the image forming apparatus 100 or from the top or bottom of the image forming apparatus 100.

Second Embodiment
A second embodiment will be described using FIGS. 6 (a) to 7 (b). According to the second embodiment, as compared with the first embodiment described above, the developing devices 4a to 4d can be mounted without being installed in the frame 100a (see FIG. 4A). The configuration of mechanism 200 is different. The other configurations and actions are the same as in the first embodiment, and therefore the same symbols are given to the same configurations to omit or simplify the description and the illustration, and in the following, descriptions will be mainly made on parts different from the first embodiment. Do. 6A to 7B, illustration of a part of the apparatus main body (a part of the side plate or the rail member 35, etc.) is omitted to facilitate understanding of the description.

  As shown in FIG. 6A, in the image forming apparatus 100A of the present embodiment, as in the first embodiment described above, the developing container 41 has a contact surface 41b formed on the outer surface, and a toner density sensor 45 A guide portion 80 is provided to guide the light to the contact surface 41b. The apparatus main body is provided with a rail member 35 as an apparatus guiding portion so that the developing device 4A can be inserted from the horizontal direction in the mounting direction (Y direction) and installed. The rail member 35 slidably holds the developing device 4A and guides the developing device 4 to the mounting position (predetermined position) of the apparatus main body. The developing device 4A is detachably provided when the cover 300 is in the open position.

  A toner concentration sensor 45 is disposed on the rail member 35, which is a part of the apparatus main body, in order to detect the toner concentration of the developer in the developing device 4 (more specifically, in the developing container). The toner concentration sensor 45 is loosely fitted in the loosely fitted portion 110, and is urged in a direction toward the developing container 41 side by a pressure spring (not shown) as an urging portion. However, in the present embodiment, unlike the first embodiment, the loose fitting portion 110 is provided so as to be vertically movable, and the loose fitting portion 110 is moved along with the mounting operation of the developing device 4A. It is made to contact | abut to the contact surface 41b. In the case of the present embodiment, a boss-shaped projection 410 is formed on the outer surface of the developing container 41 as a moving mechanism 200 for moving the loosely fitting portion 110 up and down, and a swing lever 90 is provided on the rail member 35.

  The protrusion 410 as the engaging portion is formed to project from the outer surface of the developing container 41 in the direction intersecting the mounting direction (Y direction) of the developing device 4A and the direction intersecting the vertical direction (Z direction). . On the other hand, the rocking lever 90 as a rocking member is provided so as to be able to rock on the rocking center 90c as a fulcrum by being engaged with the projection 410 with the mounting operation of the developing device 4A. To do so, the rocking lever 90 has an engaged portion 90 b that slides on the protrusion 410. Further, the swing lever 90 has a lever portion 90a which moves the loose fitting portion 110 up and down in response to the swing.

  The vertical movement of the loose fitting portion 110 by the rocking lever 90 will be described. As shown in FIG. 6B, with the mounting operation of the developing device 4A, the projection 410 abuts on the engaged portion 90b of the rocking lever 90. When the mounting operation of the developing device 4A is further continued from this state, the engaged portion 90b is pushed by the projection 410 in the Y direction, and the rocking lever 90 starts to rock. Then, the lever portion 90 a of the rocking lever 90 contacts the loose fitting portion 110 and pushes up the loose fitting portion 110. The pushed up loose fitting portion 110 moves along the guide portion 80.

  When mounting of the developing device 4A is completed, as shown in FIGS. 7A and 7B, the loosely fitted portion 110 is maintained in a state of being supported from below by the lever portion 90a. In this state, the loosely fitted portion 110 is held by the guide portion 80, and the toner density sensor 45 is abutted against the abutment surface 41b (see FIG. 6A). That is, in the case of the present embodiment, before the mounting operation of the developing device 4A is started, the toner concentration sensor 45 is retracted to a position where it does not abut on the developing container 41 (specifically, the contact surface 41b). Then, in the middle of the mounting operation of the developing device 4A, the toner density sensor 45 is raised toward the contact surface 41b in response to the free fitting portion 110 being lifted by the swing lever 90. When the developing device 4A is mounted at a predetermined position, the toner density sensor 45 reaches the contact surface 41b and is in contact with the contact surface 41b.

  Also in the present embodiment, as in the first embodiment described above (see FIG. 5), after the mounting of the developing device 4 to the predetermined position is completed, the toner density sensor 45 is pressed by the pressing spring 61 and abuts against the developing container 41 As a result, movement in the substantially X direction is restricted. The movement in the substantially Y direction is restricted by the first guide 80a, and the movement in the substantially Z direction is restricted by the second guide 80b. Thus, the toner density sensor 45 is stably in contact with the contact surface 41b. Further, the toner concentration sensor 45 is pressed against the wall surface (contact surface 41b) of the developing container 41 by the pressing spring 61, whereby the detection accuracy of the toner concentration is further enhanced.

  As described above, in the second embodiment as well as the first embodiment described above, the toner concentration sensor 45 for detecting the toner concentration of the developer in the developing container 41 is disposed in the apparatus main body. Then, the toner concentration sensor 45 is brought into contact with the developing container 41 (specifically, the contact surface 41b) with the mounting operation of the developing device 4 so that the toner concentration of the developer in the developing container 41 can be detected. However, unlike the first embodiment, the toner density sensor 45 is brought into contact with the developing container 41 by moving the loose fitting portion 110 in which the toner density sensor 45 is loosely fitted by means of the rocking lever 90. Also in the second embodiment, the same effect as that of the first embodiment can be obtained that the downsizing and cost reduction of the developing device 4 as a replacement part can be realized.

Other Embodiments
In the first and second embodiments described above, the case where the developing device 4 is mounted alone on the apparatus main body is described as an example, but the present invention is not limited to this. For example, when the photosensitive drum 1 and the developing device 4 are an integral image forming unit, the toner density sensor 45 provided in the main body of the apparatus serves as a developing container 41 of the developing device 4 of the image forming unit. (In detail, it may be in contact with the contact surface 41b).

  As a modification of the embodiment shown in FIG. 4A, the toner density sensor 45 may be disposed in the housing including the loose fitting portion 60. Then, for example, after the frame 100a is stored in the housing, the toner density sensor 45 is brought into contact with the mounting operation of moving the developing devices 4a to 4d together with the frame 100a in the vertical direction and mounting the frame 100a in the housing. It is preferable to abut on the surface 41b.

1 (1a, 1b, 1c, 1d) ... photosensitive member (photosensitive drum), 4 (4a, 4b, 4c, 4d) ... developing device, 35 ... device main body (device guide portion, rail member), 41 ... developing container, 41b: contact surface, 41c: guide surface, 45: detection means (toner density sensor), 60 (110): loose fitting portion, 61: biasing portion (pressing spring), 80: detection guide portion (guide portion), 90: rocking member (rocking lever), 100: image forming apparatus, 100a: apparatus main body (frame), 200: moving mechanism, 300: cover, 410: engaging portion (protrusion)

Claims (9)

The device body,
A photoreceptor on which an electrostatic latent image is formed;
The image forming apparatus further includes a developing container detachably provided in the apparatus main body and containing a developer containing toner and a carrier, and the electrostatic latent image formed on the photosensitive member by the developer contained in the developing container is a toner image A developing device for developing
A detection unit disposed in the apparatus main body and capable of detecting the toner concentration of the developer contained in the developing container in contact with the contact surface of the developing container;
The detection means is brought into contact with the contact surface in accordance with a mounting operation in which the developing device is mounted at a predetermined position of the apparatus main body.
An image forming apparatus characterized by The detection means is provided so as to be movable along with the mounting operation of the developing device.
A moving mechanism for moving the detection means to the contact surface in accordance with the mounting operation of the developing device;
The image forming apparatus according to claim 1, A loose fitting portion for loosely fitting the detection means;
The moving mechanism has a biasing portion for biasing the detection means loosely fitted to the loosely fitting portion in a direction toward the developing container side.
The image forming apparatus according to claim 2, The developing container has a guide surface formed to slide on the detection means with the mounting operation of the developing device to move the detection means in the direction opposite to the urging direction of the urging unit.
The image forming apparatus according to claim 3, The moving mechanism is provided on the developing container, and an engaging portion which protrudes from the outer surface of the developing container in a direction intersecting the mounting direction of the developing device, and the engaging portion along with the mounting operation of the developing device. And a rocking member engaged and rockable
The image forming apparatus according to any one of claims 2 to 4, characterized in that: The developing container has a detection guide portion for guiding the detecting means to the contact surface in accordance with the mounting operation of the developing device.
The image forming apparatus according to any one of claims 1 to 5, wherein The apparatus main body is provided so as to be horizontally insertable and removable, and has a frame in which the developing device can be installed in a pulled out state.
The detection means is disposed in the frame body,
The image forming apparatus according to any one of claims 1 to 6, wherein The detection means abuts on the contact surface when the developing device is installed on the frame.
The image forming apparatus according to claim 7, wherein The apparatus main body has an apparatus guide portion for guiding the developing device to the predetermined position so as to slide.
The detection means is disposed in the device guide unit.
The image forming apparatus according to any one of claims 1 to 6, wherein

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