Developing device and image forming device equipped with developing device

Abstract

To provide a developing device with which sticking of a stagnant developer is suppressed, and an image forming device equipped with the developing device.SOLUTION: The developing device comprises: a developing tank that accommodates a developer and is divided into first and second storage chambers and first and second communication parts that communicate with these chambers at respectively different positions; a first conveyance screw including a first revolving shaft provided inside the first storage chamber and the first and second communication parts, and a first spiral blade provided on the circumferential surface thereof; and a second conveyance screw including a second revolving shaft provided parallel to the first revolving shaft inside the second storage chamber and the first and second communication parts, and a second spiral blade provided on the circumferential surface thereof. In the inside of the first communication part, the first conveyance screw has a first paddle protruding from the circumferential face of the first revolving shaft and extending along an axial direction of the first revolving shaft; in the inside of the first communication part, the second conveyance screw has a second paddle protruding from the circumferential face of the second revolving shaft and extending along an axial direction of the second revolving shaft.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present disclosure relates to a developing device and an image forming apparatus including the developing device. [Background technology]

[0002] Generally, electrophotographic image forming devices use a two-component developer that contains toner and a carrier, which is a magnetic carrier material. In the developing device, the toner and carrier are stirred together and rubbed against each other, causing the toner to become charged. The charged toner is carried by the carrier to a developing roller, from which it is supplied to the surface of a photoconductor drum, where the electrostatic latent image formed on the surface of the photoconductor drum is developed. The toner image developed on the photoconductor drum is transferred to paper, and the toner image is fixed to the paper by a fixing device.

[0003] Some of the image forming apparatuses described above are equipped with a developing device that circulates the developer while stirring it so that the developer can charge the toner quickly and sufficiently in order to achieve high speed and compactness. For example, Patent Document 1 discloses a developing device that has a first developer stirring and transporting member and a second developer stirring and transporting member that stir and transport the developer using a screw, and circulates the developer between the two stirring and transporting members. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2003-263012 A Summary of the Invention [Problem to be solved by the invention]

[0005] Patent Document 1 discloses an impeller for feeding developer from a second developer stirring and transporting member to a first developer stirring and transporting member. However, depending on the positional relationship between the first developer stirring and transporting member and the second developer stirring and transporting member, it is difficult for all of the developer to be fed by the impeller, and some of the developer may return to the second developer stirring and transporting member side or remain between the first developer stirring and transporting member and the second developer stirring and transporting member. In particular, when the first developer stirring and transporting member is disposed at a higher position than the second developer stirring and transporting member, the above tendency becomes more pronounced.

[0006] In addition, toner contains external additives such as silica to improve fluidity, but when the developer is stirred and circulated for a long time in the developing device, the external additives are separated from the toner or embedded in the toner, reducing the fluidity of the toner. When developer containing toner with reduced fluidity is retained in the middle of the transport path, the retained developer acts as a seed to cause the toner and carrier to adhere to the bottom surface of the transport path, etc. As a result, problems occur in which the developer transport is hindered by the adhered matter, or part of the adhered matter peels off due to physical load and becomes a lump and is supplied to the developing roller, causing image defects.

[0007] In view of the above problems, the present disclosure has an object to provide a developing device that suppresses adhesion of accumulated developer and an image forming apparatus including the developing device. [Means for solving the problem]

[0008] A developing device according to one aspect of the present disclosure includes a developer tank that is divided into a first storage chamber, a second storage chamber, and a first communication portion and a second communication portion that communicate the first storage chamber and the second storage chamber at different positions, and that contains a developer; a first rotating shaft that is provided inside the first storage chamber, the first communication portion, and the second communication portion, and a first helical blade that is provided on a circumferential surface of the first rotating shaft, and that rotates to transport the developer from the second communication portion toward the first communication portion; a second rotating shaft that is provided inside the second storage chamber, the first communication portion, and the second communication portion so as to be parallel to the first rotating shaft, and a second helical blade that is provided on the circumferential surface of the second rotating shaft, and that rotates. and a second conveying screw that conveys the developer from the first communicating portion to the second communicating portion, and a developer carrier provided above the second conveying screw. Inside the first communicating portion, the first conveying screw has a first paddle that is a protruding member that protrudes from the circumferential surface of the first rotating shaft and extends along the axial direction of the first rotating shaft, and inside the first communicating portion, the second conveying screw has a second paddle that is a protruding member that protrudes from the circumferential surface of the second rotating shaft and extends along the axial direction of the second rotating shaft. The developer is sent from the first storage chamber through the second communicating portion to the second storage chamber, and from the second storage chamber to the first storage chamber through the first communicating portion, thereby circulating within the developer tank. [Brief description of the drawings]

[0009] [Figure 1] 1 is a schematic cross-sectional view showing an internal structure of an image forming apparatus according to the present disclosure. [Diagram 2] 2 is a schematic cross-sectional view showing the details of the developing device in FIG. 1. [Diagram 3] 1 is a block diagram showing a portion of an image forming apparatus according to the present disclosure. [Figure 4] FIG. 2 is a perspective view of a developing device according to the first embodiment. [Diagram 5] FIG. 4 is a perspective view of the developing device of FIG. 3 with a part cut away. [Figure 6] FIG. 5 is a cross-sectional view taken along line VV of FIG. 4. [Figure 7] FIG. 2 is a partially cutaway perspective view of the developing device of the first embodiment. [Figure 8]FIG. 7 is a cross-sectional view taken along line VII-VII of FIGS. 4 and 6. [Figure 9] 5A to 5C are cross-sectional views showing the movement of developer in a first communicating portion according to the first embodiment. [Figure 10] 5A to 5C are cross-sectional views showing the movement of the developer in a first communication portion according to the first embodiment. [Figure 11] 5A to 5C are cross-sectional views showing the movement of developer in a first communicating portion according to the first embodiment. [Figure 12] 3 is a perspective view showing the periphery of one end of a first conveying screw according to the first embodiment. FIG. [Figure 13] 3 is a perspective view showing the periphery of one end of a second conveying screw according to the first embodiment. FIG. [Figure 14] FIG. 11 is a partially cutaway perspective view of a developing device according to a second embodiment. [Figure 15] FIG. 11 is a cross-sectional view showing a developing device according to a third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In addition, in the drawings, the same or similar elements are given the same reference numerals, and duplicated explanations are omitted. In addition, the embodiments described below do not unduly limit the contents of the present disclosure described in the claims, and all of the configurations described in the embodiments are not necessarily essential as a solution to the present disclosure.

[0011] <Image forming device> 1 is a schematic cross-sectional view showing the internal structure of an image forming apparatus 100 according to the present disclosure. The image forming apparatus 100 is, for example, a multifunction machine having a copying function, a printer function, a scanner function, a facsimile function, etc., and forms a multicolor or monochrome image on a printing paper by an electrophotographic method. Note that the image forming apparatus 100 according to the present disclosure is not limited to a multifunction machine, and may be, for example, a printing machine having only a printer function.

[0012] The image forming apparatus 100 includes, for example, a main body 101 and an image reading device 102 disposed above the main body 101. The image reading device 102 includes a document feeder that automatically feeds documents one by one, and an image reading unit that reads images of the documents, and generates image data based on the images of the documents read by the image reading unit.

[0013] The main body 101 includes a control device 103, a photoconductor 104, a developing device 200, an exposure device 105, a toner cartridge 106, a transfer unit 107, an automatic paper feed tray 111, a manual paper feed tray 112, a paper discharge tray 113, and the like.

[0014] The control device 103 is a device that controls the image forming apparatus 100. The control device 103 is composed of a microcontroller and peripheral circuits. The microcontroller includes a processor and a memory. The processor executes a control program stored in the memory to operate the microcontroller and the peripheral circuits as the control device 103. All or part of the processing performed by the microcontroller may be performed by a dedicated electronic circuit.

[0015] Furthermore, the control device 103 includes a communication unit and the like that receives data, signals, and the like from the outside. The control device 103 transmits various data such as images, control signals, and the like to each device included in the image forming apparatus 100 in response to an input operation by a user, reception of data from the outside, and the like, and causes the image forming apparatus 100 to execute various operations.

[0016] The photoconductor 104 comprises a cylindrical conductive substrate and a photosensitive layer provided on the outside of the substrate. The photosensitive layer is insulating when not irradiated with light, and is conductive in areas irradiated with light. The peripheral surface of the photosensitive layer is charged to a predetermined potential by a charger (not shown). The photoconductor 104 has a rotating shaft (not shown) aligned along its axis, and is rotated around the rotating shaft by an electric motor (not shown).

[0017] The exposure device 105 irradiates light for exposing the peripheral surface of the photosensitive layer of the photoconductor 104. Based on image data transmitted from the control device 103, the exposure device 105 irradiates the peripheral surface of the photosensitive layer of the photoconductor 104 with light for forming an image based on the image data. The charged peripheral surface of the photoconductor 104 is exposed to the light irradiated by the exposure device 105, and an electrostatic latent image corresponding to the image data is formed on the peripheral surface of the photosensitive layer of the photoconductor 104.

[0018] The developing device 200 includes a developing tank that contains a two-component developer, which is a mixture of toner and carrier supplied from the toner cartridge 106, and a developing roller attached to the developing tank. The developing device 200 supplies toner onto the circumferential surface of the photosensitive layer of the photoconductor 104 via the developer carrier 203, and develops the electrostatic latent image on the circumferential surface of the photoconductor 104 to form a toner image. Details of the developing device 200 will be described later.

[0019] This disclosure illustrates an image forming apparatus 100 capable of printing full-color images, which realizes full-color image printing by superimposing monochromatic images corresponding to each of the four colors of cyan, magenta, yellow, and black. Thus, the image forming apparatus 100 includes four toner cartridges 106 that accommodate toner of each of the four colors, four photoconductors 104 that correspond to each of the four colors, an exposure device 105 that exposes each of the four photoconductors 104, and four developing devices 200. For example, each of the four photoconductors 104 and the four developing devices 200 has the same structure, and only the color of the toner supplied from the toner cartridges 106 to the developing devices 200 is different. Although not illustrated in this disclosure, an image forming apparatus capable of printing monochrome images is composed of only a toner cartridge, photoconductor, exposure device, and developing device corresponding to black, unlike a full-color image.

[0020] The transfer unit 107 is disposed above the four photoconductors 104, and includes four primary transfer rollers 108 corresponding to the four photoconductors 104, a transfer belt 109 that is stretched by a drive roller 114 and a tension roller 115 and driven to rotate by the drive roller 114, and a secondary transfer roller 110. The drive roller 114 is rotated by an electric motor (not shown), and when the drive roller 114 rotates, the transfer belt 109 rotates. The primary transfer roller 108 and the secondary transfer roller 110 are each journaled on the transfer unit 107 so as to rotate together with the transfer belt 109 as it rotates.

[0021] When a current is supplied to the primary transfer roller 108 from a primary transfer power supply (not shown), a transfer electric field is formed between the photoconductor 104 and the transfer belt 109 at the position of the primary transfer roller 108. The toner image developed on the circumferential surface of the photoconductor 104 is transferred onto the transfer belt 109 by the action of the transfer electric field. Toner images corresponding to each of the four colors, cyan, magenta, yellow, and black, are sequentially transferred and superimposed onto the transfer belt 109 by each of the four primary transfer rollers 108, and a full-color toner image is formed on the transfer belt 109.

[0022] The secondary transfer roller 110 is a member that transfers a toner image onto a print sheet, and is disposed so as to contact the transfer belt 109 on the drive roller 114. The print sheet fed from the automatic paper feed tray 111 or the manual paper feed tray 112 is conveyed by a plurality of conveying rollers and passes between the secondary transfer roller 110 and the transfer belt 109. When the print sheet passes between the secondary transfer roller 110 and the transfer belt 109, the toner image formed on the transfer belt 109 is transferred onto the print sheet. The toner image transferred onto the print sheet is heated and pressed by a heating roller, a pressure roller, etc. (not shown) to be fixed onto the print sheet. As described above, the image forming apparatus 100 completes printing of an image onto the print sheet based on the received image data. The print sheet on which printing has been completed is discharged to the paper discharge tray 113.

[0023] <Developing device> Fig. 2 is a schematic cross-sectional view showing details of the developing device 200 of the present disclosure shown in Fig. 1. The developing device 200 has a developing tank 202, in which a developer carrier 203, a first transport screw 320, a second transport screw 420, etc. are arranged. Note that in these figures, the developer contained in the developing tank 202 is omitted unless necessary.

[0024] The lower part of the inside of the developing tank 202 is divided into a first storage chamber 300 and a second storage chamber 400 by a partition wall 205. A first conveying screw 320 is disposed inside the first storage chamber 300, and a second conveying screw 420 is disposed inside the second storage chamber 400. The first conveying screw 320 has a first rotating shaft 321 and a first helical blade 324 provided on a first circumferential surface 322 of the first rotating shaft 321. The second conveying screw 420 has a second rotating shaft 421 and a second helical blade 424 provided on a second circumferential surface 422 of the second rotating shaft 421.

[0025] 3 is a block diagram showing a part of the image forming apparatus 100 according to the present disclosure. The first conveying screw 320 is rotated by the first electric motor 325, and the second conveying screw 420 is rotated by the second electric motor 425. The control device 103 controls the rotation speed of the first electric motor 325 and the rotation speed of the second electric motor 425. As will be described in detail later, the first conveying screw 320 and the second conveying screw 420 rotate, so that the developer is conveyed so as to circulate inside the first storage chamber 300 and the second storage chamber 400. Note that, in the developing device 200 according to the present disclosure, a configuration in which the second storage chamber 400 is arranged at a higher position than the first storage chamber 300 is illustrated as an example, but these storage chambers may be arranged at the same height as each other.

[0026] The developer carrier 203 is disposed above the second conveying screw 420. For example, the developer carrier 203 is a roller-shaped member, and is rotated by a developer carrier motor 206 as shown in FIG. 3. The control device 103 controls the rotation speed of the developer carrier motor 206. The developer in the second storage chamber 400 is carried on the peripheral surface of the developer carrier 203. The developer carrier 203 faces the photoconductor 104. The toner contained in the developer is charged, and is attracted to the electrostatic latent image formed on the peripheral surface of the photoconductor 104 by electrostatic attraction. As a result, the toner is transferred from the developer carried on the peripheral surface of the developer carrier 203 onto the peripheral surface of the photoconductor 104, and a toner image corresponding to the electrostatic latent image is formed.

[0027] <Embodiment 1> Fig. 4 is a perspective view of the developing device 200 according to the first embodiment of the present disclosure. Fig. 5 is a perspective view of the developing device 200 of Fig. 4 with a part cut away.

[0028] As shown in Fig. 4, developing device 200 includes developing tank 202. An upper portion of developing tank 202 is open, and developer carrier 203 is partially exposed. One end of developing tank 202 is provided with toner supply port 204. Depending on the amount of toner remaining inside developing tank 202, toner is appropriately supplied from toner cartridge 106 shown in Fig. 1 into developing tank 202 through toner supply port 204.

[0029] As shown in FIG. 5, inside the developing tank 202, the developer carrier 203, the first transport screw 320, the second transport screw 420, etc. are arranged. The lower part of the inside of the developing tank 202 is divided into a first storage chamber 300 and a second storage chamber 400 by a partition wall 205. Inside the first storage chamber 300, the first transport screw 320 is arranged, and inside the second storage chamber 400, the second transport screw 420 is arranged. The first transport screw 320 has a first rotating shaft 321 and a first spiral blade 324 provided on a first circumferential surface 322 of the first rotating shaft 321. The second transport screw 420 has a second rotating shaft 421 and a second spiral blade 424 provided on a second circumferential surface 422 of the second rotating shaft 421.

[0030] 3, the first conveying screw 320 and the second conveying screw 420 are rotated by a first electric motor 325 and a second electric motor 425. The developer is conveyed by the first conveying screw 320 in a first direction along the first rotating shaft 321 inside the first storage chamber 300. The developer is conveyed by the second conveying screw 420 in a second direction opposite to the first direction, which is a direction along the second rotating shaft 421 inside the second storage chamber 400.

[0031] Fig. 6 is a cross-sectional view taken along the line VI-VI in Fig. 5. Partition walls 205 are not provided at either end of developing tank 202 in the first direction, and two communication parts that communicate with first storage chamber 300 and second storage chamber 400 are separated at each of the end parts. As shown in Fig. 6, a first communication part 310 and a second communication part 410 that communicate with first storage chamber 300 and second storage chamber 400 are separated at one end and the other end of the inside of developing tank 202. The first communication part 310 and the second communication part 410 communicate with first storage chamber 300 and second storage chamber 400 at different positions.

[0032] That is, the first conveying screw 320 is disposed inside the first storage chamber 300, the first communicating portion 310, and the second communicating portion 410. The first rotating shaft 321 of the first conveying screw 320 and the first spiral blade 324 provided on the first circumferential surface 322 are rotated by the first electric motor 325. The developer inside the developing tank 202 is conveyed inside the first storage chamber 300 in the first direction from the second communicating portion 410 toward the first communicating portion 310 as the first conveying screw 320 rotates. The developer conveyed inside the first storage chamber 300 is sent to the second storage chamber 400 through the first communicating portion 310.

[0033] Similarly to the first conveying screw 320, the second conveying screw 420 is disposed inside the second storage chamber 400, the first communicating portion 310, and the second communicating portion 410. The second rotating shaft 421 and the second spiral blade 424, which is spirally provided on the second circumferential surface 422 of the second conveying screw 420, are rotated by the second electric motor 425. Here, the second rotating shaft 421 is provided parallel to the first rotating shaft 321. The developer inside the developing tank 202 is conveyed inside the second storage chamber 400 in the second direction from the first communicating portion 310 toward the second communicating portion 410 by the rotation of the second conveying screw 420. Then, the developer conveyed inside the second storage chamber 400 is sent to the first storage chamber 300 through the second communicating portion 410. Also, the toner is supplied from the toner cartridge 106 to the inside of the second communicating portion 410 through the toner supply port 204.

[0034] As described above, the developer is sent from first storage chamber 300 through first communication part 310 to second storage chamber 400, and then sent from second storage chamber 400 to first storage chamber 300 through second communication part 410, thereby circulating inside developer tank 202. By circulating the developer inside developer tank 202, the supplied toner can be dispersed evenly throughout the developer, and an appropriate amount of charge can be imparted to the toner.

[0035] <Rotational speed of the first conveying screw and the second conveying screw> For example, it is preferable that the first conveying screw 320 and the second conveying screw 420 rotate at the same rotation speed. For example, in the configuration shown in Fig. 3, the control device 103 can control the rotation speed of the first electric motor 325 and the rotation speed of the second electric motor 425 to be the same speed. This makes the conveying speed of the developer circulating inside the developing tank 202 constant, and makes it possible to suppress variation in the distribution of the developer inside the developing tank 202.

[0036] In the present disclosure, the first conveying screw 320 and the second conveying screw 420 do not have to be rotated by different electric motors. For example, when the rotation speed of the first conveying screw 320 and the rotation speed of the second conveying screw 420 are set to the same speed, both the first conveying screw 320 and the second conveying screw 420 may be rotated by one common electric motor.

[0037] <1st communication section> Fig. 7 is a perspective view of the developing device 200 of the first embodiment, with a part cut away. More specifically, Fig. 7 is a cutaway view of the other end of the developing device 200 of Figs. 5 and 6, opposite to the end where the toner supply port 204 is located, for the purpose of easily explaining the internal structure of the first communication portion 310 shown in Fig. 5. Fig. 8 is a cross-sectional view taken along the line VIII-VIII of Figs. 5 and 7.

[0038] 7 and 8, the first conveying screw 320 has a first paddle 500 including a first protruding member 501 protruding from the first circumferential surface 322 and extending along the axial direction of the first rotating shaft 321 inside the first communicating portion 310. The second conveying screw 420 has a second paddle 600 including a second protruding member 601 protruding from the second circumferential surface 422 and extending along the axial direction of the second rotating shaft 421 inside the first communicating portion 310.

[0039] The developer transported by the first transport screw 320 from the first storage chamber 300 to the inside of the first communication section 310 is pushed by the first paddle 500 toward the side of the first communication section 310 where the second transport screw 420 is disposed. The developer pushed toward the second transport screw 420 side is transported by the second transport screw 420 to the second storage chamber 400, but a portion of the developer remains inside the first communication section 310 without being transported.

[0040] <Details of the movement of developer in the first communication portion> 9 to 11 are cross-sectional views showing the movement of the developer 201 inside the first communication portion 310 of the first embodiment, and the movement of the developer 201 inside the first communication portion 310 progresses in chronological order from FIG. 9 to FIG. 11.

[0041] 9, the developer 201 on the bottom surface 311 of the first communication portion 310 at a position between the first paddle 500 and the second paddle 600 may become less fluid and accumulate under a high humidity environment. The accumulated developer 201 includes the developer transported from the first storage chamber 300 to the inside of the first communication portion 310 by the first transport screw 320 and the developer remaining inside the first communication portion 310 without being transported to the second storage chamber 400. The first paddle 500 rotates in a direction moving from the bottom surface 311 side of the first communication portion 310 toward the second paddle 600, and moves so as to approach the developer 201.

[0042] 10, the first paddle 500 comes into contact with the developer 201 and pushes out the developer 201 toward the side where the second transport screw 420 is disposed, which is the rotation direction of the first paddle 500. At this time, the developer 201 pushed out by the first paddle 500 moves from the first communication portion 310 to the second storage chamber 400, and is transported in the second direction by the second spiral blade 424.

[0043] However, the developer 201 pushed out by the first paddle 500 does not all move to the second storage chamber 400, but a portion of the developer 201 remains inside the first communication portion 310. The remaining portion of the developer 201 remains on the bottom surface 311 at a position between the first paddle 500 and the second paddle 600, for example, as shown in Fig. 9. When the developer containing the toner whose fluidity has decreased due to being stirred and circulated for a long time inside the developing tank 202 remains, the toner and carrier tend to adhere to the bottom surface 311 using the remaining developer as seeds.

[0044] Therefore, in the developing device 200 of the present disclosure, as shown in FIG. 11, the second paddle 600 comes into contact with the developer 201 and pushes the developer 201 back toward the side where the first conveying screw 320 is disposed, which is the rotation direction of the second paddle 600. The pushed back developer 201 is then pushed out again by the first paddle 500. In this manner, in the developing device 200 according to the first embodiment of the present disclosure, the first paddle 500 and the second paddle 600 alternately stir the developer 201 remaining inside the first communicating portion 310 in different directions, so that the developer 201 remaining inside the first communicating portion 310 is always moving. This prevents the toner and carrier from adhering to the bottom surface 311, and prevents the developer 201 from being impeded by the adhering matter, or prevents a part of the adhering matter from becoming a lump and peeling off to be supplied to the developer carrier 203, resulting in defects in the printed image.

[0045] <Rotation direction of the first and second paddles> 8, in the first embodiment, for example, the first conveying screw 320 rotates in a direction in which the first paddle 500 moves from the bottom surface 311 side of the first communicating portion 310 toward the second paddle 600. The second conveying screw 420 rotates in a direction opposite to that of the first conveying screw 320. In other words, the second paddle 600 rotates in a direction in which the second paddle 600 moves from the bottom surface 311 side of the first communicating portion 310 toward the first paddle 500. As a result, the first paddle 500 and the second paddle 600 move so as to scrape up the developer 201 from the bottom surface 311 where the developer 201 is likely to accumulate, so that the developer 201 or the toner and carrier contained in the developer 201 can be further prevented from adhering to the bottom surface 311.

[0046] <Installation height of the first and second rotating shafts> 8 to 11, in the first embodiment, the second rotating shaft 421 is disposed at a higher position than the first rotating shaft 321, and the bottom surface 311 is an upwardly inclined surface 312 that faces from the position where the first paddle 500 is located to the position where the second paddle 600 is located. With this configuration, the maximum dimension of the developing device 200 in the horizontal direction can be reduced. However, since the bottom surface 311 is the upwardly inclined surface 312, a part of the developer 201 pushed out by the first paddle 500 tends to slide down due to gravity and remain inside the first communicating portion 310, and the amount of the developer 201 remaining inside the first communicating portion 310 increases, and the sticking of the developer 201 on the upwardly inclined surface 312 tends to occur. Therefore, in the developing device 200 having the above-described configuration, it is very effective to alternately move the developer 201 accumulated inside the first communicating portion in opposite directions using the first paddle 500 and the second paddle 600 of the present disclosure, thereby suppressing the occurrence of stuck matter.

[0047] <Number of First Protruding Members and Second Protruding Members and Installation Intervals> As shown in FIG. 8, in the first embodiment, the first paddle 500 includes two first protruding members 501, and the two first protruding members 501 are provided at 180 degree intervals along the first circumference 323 of the first rotating shaft 321. In other words, the angle θ1 between the two first protruding members 501 is 180 degrees around the center point of the first rotating shaft 321. Similarly, the second paddle 600 includes two second protruding members 601, and the two second protruding members 601 are provided at 180 degree intervals along the second circumference 423 of the second rotating shaft 421. With this configuration, the first paddle 500 and the second paddle 600 can push out the developer twice each while the first rotating shaft 321 and the second rotating shaft 421 make one rotation, and the developer 201 can be moved and stirred efficiently inside the first communicating portion 310.

[0048] <Rotation timing of the first and second paddles> It is preferable that the developing device 200 rotates the first conveying screw 320 and the second conveying screw 420 such that the first paddle 500 and the second paddle 600 are out of phase with each other and the first end side 502 and the second end side 602 do not face each other. More specifically, the first protruding member 501 constituting the first paddle 500 has the first end side 502 on the tip side protruding from the first circumferential surface 322. The second protruding member 601 constituting the second paddle 600 has the second end side 602 on the tip side protruding from the second circumferential surface 422. For example, in the configurations of FIGS. 9 to 11, the first conveying screw 320 and the second conveying screw 420 rotate at the same rotation speed. 9, when the second end side 602 faces the first conveying screw 320, the first end side 502 does not face the second conveying screw 420, and the first end side 502 and the second end side 602 do not face each other. Also, as shown in FIG. 11, when the first end side 502 faces the second conveying screw 420, the second end side 602 does not face the first conveying screw 320, and the first end side 502 and the second end side 602 do not face each other. This makes it possible to prevent the first paddle 500 and the second paddle 600 from pushing the developer 201 in opposite directions at the same time, and the developer 201 is not prevented from moving from the first communication portion 310 to the second storage chamber 400. As long as the first end side 502 and the second end side 602 do not face each other, the rotation speeds of the first conveying screw 320 and the second conveying screw 420 may be different from each other.

[0049] <An example of the first conveying screw in the first embodiment> FIG. 12 is a perspective view showing an example of a detailed structure around one end of the first conveying screw 320 in the first embodiment. The first protruding member 501 constituting the first paddle 500 is twisted in the opposite direction to the rotation direction of the first rotating shaft 321 as it proceeds in the first direction from the side closest to the first spiral blade 324. As a result, the first end side 502 is in a twisted position with respect to the axial direction of the first rotating shaft 321. FIG. 12 illustrates a configuration in which the first protruding member 501 constituting the first paddle 500 is twisted at a twist angle θ2. When the first protruding member 501 pushes out the developer toward the side where the second conveying screw 420 is arranged, the first protruding member 501 pushes out the developer sequentially from the side close to the first spiral blade 324 to the side far from the first spiral blade 324. That is, the timing at which the first protruding member 501 pushes out the developer varies depending on the location of the first protruding member 501 in the first direction, which causes a vortex-like motion in the pushed-out developer. This can further increase the effect of stirring the developer 201 remaining inside the first communicating portion 310, and can further prevent the developer 201 from sticking to the bottom surface 311.

[0050] 12, the torsion angle θ2 of the first protruding member 501 is preferably set in the range of, for example, 30 degrees to 90 degrees. With an angle in this range, a vortex-like motion can be generated in the developer pushed out by the first protruding member 501, while a sufficient amount of developer can be pushed out by the first protruding member 501.

[0051] <An example of the second conveying screw in the first embodiment> FIG. 13 is a perspective view showing an example of a detailed structure around one end of the second conveying screw 420 in the first embodiment. The second protruding member 601 constituting the second paddle 600 is twisted in the opposite direction to the rotation direction of the second rotating shaft 421 as it proceeds in the second direction from the side farthest from the first spiral blade 324. As a result, the second end side 602 is in a twisted position with respect to the axial direction of the second rotating shaft 421. FIG. 13 illustrates a configuration in which the second protruding member 601 constituting the second paddle 600 is twisted at a twist angle θ2. When the second protruding member 601 pushes back the developer toward the side where the first conveying screw 320 is disposed, the developer is pushed back sequentially from the side farther from the second spiral blade 424 of the second protruding member 601 toward the closer side. That is, the timing at which the second protruding member 601 pushes back the developer varies depending on the location of the second protruding member 601 in the second direction, and a vortex-like motion is generated in the pushed-back developer. This can further increase the effect of stirring the developer 201 remaining inside the first communication portion 310, and can further prevent the developer 201 from sticking to the bottom surface 311.

[0052] 13, the torsion angle θ2 of the second protruding member 601 is preferably in the range of, for example, 30 degrees to 90 degrees. With an angle in this range, a sufficient amount of developer pushed back by the second protruding member 601 can be secured while a vortex-like motion is generated in the developer pushed back by the second protruding member 601. Note that the torsion angle θ2 of the first protruding member 501 and the torsion angle of the second protruding member 601 do not have to be the same angle, and for example, the torsion angle of the first protruding member 501 and the torsion angle of the second protruding member 601 may be different angles.

[0053] <An example of the first helical blade and the second helical blade of the first embodiment> As shown in Fig. 12, the first helical blade 324 may be a double-blade blade 700 in which two first helical blades 324 are attached with a 180 degree offset. As shown in Fig. 13, the second helical blade 424 may be a double-blade blade 700 in which two second helical blades 424 are attached with a 180 degree offset. By the first conveying screw 320 and the second conveying screw 420 being double-flight screws with the double-blade blade 700, the developer conveying efficiency inside the first storage chamber 300 and the second storage chamber 400 can be improved compared to the case where the first conveying screw 320 and the second conveying screw 420 are standard screws with one first helical blade 324 and one second helical blade 424.

[0054] <Embodiment 2> 14 is a partially cutaway perspective view of a developing device 200 according to the second embodiment. The developing device 200 according to the second embodiment differs from the first embodiment in the structure relating to the second paddle 600 of the second conveying screw 420.

[0055] In the second embodiment, as shown in FIG. 14, a part of the second helical blade 424 is provided on the second paddle 600 of the second conveying screw 420. In other words, the second helical blade 424 is extended to the inside of the first communicating portion 310, and a part of the second helical blade 424 is provided on the main surface of the second protruding member 601 included in the second paddle 600. With this configuration, the second paddle 600 pushes back the developer to suppress the accumulation of the developer inside the first communicating portion 310, and the part of the second helical blade 424 on the second paddle 600 makes it easier to transport the developer from the inside of the first communicating portion 310 to the second storage chamber 400. Therefore, the amount of developer remaining and accumulating in the first communicating portion 310 can be reduced, and the occurrence of the adhered matter on the bottom surface 311 can be further suppressed.

[0056] <Embodiment 3> 15 is a cross-sectional view showing a developing device 200 of embodiment 3. Embodiment 3 differs from embodiment 1 in that the number of protruding members constituting each of the first paddle 500 and the second paddle 600 is three.

[0057] 15, the first paddle 500 includes three first protruding members 501. The second paddle 600 includes three second protruding members 601.

[0058] 15, the three first protruding members 501 included in the first paddle 500 are provided at 120 degree intervals along the first circumference 323 of the first rotation shaft 321. In other words, the angles θ3, θ4, and θ5 between the three first protruding members 501 are each 120 degrees around the center point of the first rotation shaft 321, and the three first protruding members 501 are equally spaced along the first circumference 323. Similarly, the three second protruding members 601 included in the second paddle 600 are provided at 120 degree intervals along the second circumference 423 of the second rotation shaft 421, and the three second protruding members 601 are equally spaced along the second circumference 423. With this configuration, the first paddle 500 and the second paddle 600 can push out the developer three times each while the first rotating shaft 321 and the second rotating shaft 421 make one rotation, thereby making it possible to more efficiently move and stir the developer 201 inside the first communicating portion 310.

[0059] 15, it is more preferable to rotate the first conveying screw 320 and the second conveying screw 420 so that the first end side 502 and the second end side 602 do not face each other. In other words, the developing device 200 rotates the first conveying screw 320 and the second conveying screw 420 by shifting the rotation phase between the first paddle 500 and the second paddle 600. This makes it possible to prevent both the first paddle 500 and the second paddle 600 from pushing the developer 201 at the same time, and allows the developer 201 to be moved and stirred efficiently inside the first communication portion 310.

[0060] In addition, the number of the first protruding members 501 included in the first paddle 500 and the number of the second protruding members 601 included in the second paddle 600 are two in the above-mentioned embodiment 1 and three in the above-mentioned embodiment 3, but in the present disclosure, the number is not limited to the above-mentioned number, and the number of the first protruding members 501 included in the first paddle 500 and the number of the second protruding members 601 included in the second paddle 600 may be one each, or may be four or more each. In addition, the angle between the multiple first protruding members 501 and the angle between the multiple second protruding members 601 are not limited to the angles shown in the above-mentioned embodiment 1 and embodiment 3. Furthermore, the multiple first protruding members 501 and the multiple second protruding members 601 do not have to be provided at equal intervals along the first circumference 323 and the second circumference 423, and for example, the multiple first protruding members 501 and the multiple second protruding members 601 may be provided at different intervals along the first circumference 323 and the second circumference 423.

[0061] The present disclosure is not limited to the configurations of the above-described embodiments and modified examples, and may be replaced with a configuration that is substantially the same as the configurations shown in the above-described embodiments and modified examples, a configuration that has the same action and effect, or a configuration that can achieve the same purpose. [Explanation of symbols]

[0062] 100: Image forming device 101: Main unit 102: Image reader 103: Control device 104: Photoreceptor 105: Exposure equipment 106: Toner cartridge 107: Transcription unit 108: Primary transfer roller 109: Transfer belt 110: Secondary transfer roller 111: Automatic feeder tray 112: Manual feed tray 113: Paper output tray 114: Drive roller 115: Tension roller 200: Developing device 201: Developer 202:Developer tank 203: Developer carrier 204: Toner supply port 205: Partition wall 206: Developer carrier motor 300: First Containment Cell 310: 1st communication part 311: Bottom 312: Uphill 320: First conveying screw 321: First rotation axis 322: 1st peripheral surface 323: First Circumference 324: First spiral blade 325: 1st electric motor 400: Second Containment Cell 410:Second communication part 420: Second conveying screw 421: Second rotation axis 422: Second circumferential surface 423: 2nd Circumference 424: 2nd spiral blade 425:Second electric motor 500: 1st paddle 501: First protruding member 502: First edge 600: 2nd paddle 601: Second protruding member 602: Second edge 700: Two-rowed blade

Claims

1. a developer tank which is divided into a first storage chamber, a second storage chamber, and a first communication portion and a second communication portion which communicate the first storage chamber and the second storage chamber at different positions, and which stores a developer; a first conveying screw including a first rotating shaft provided inside the first storage chamber, the first communicating portion, and the second communicating portion, and a first helical blade provided on a peripheral surface of the first rotating shaft, the first conveying screw rotating to convey the developer from the second communicating portion toward the first communicating portion; a second conveying screw including a second rotating shaft provided inside the second storage chamber, the first communicating portion, and the second communicating portion so as to be parallel to the first rotating shaft, and a second helical blade provided on a circumferential surface of the second rotating shaft, the second conveying screw rotating to convey the developer from the first communicating portion toward the second communicating portion; a developer carrier provided above the second conveying screw, In the first communication portion, the first conveying screw has a first paddle which is a protruding member protruding from a peripheral surface of the first rotating shaft and extending along an axial direction of the first rotating shaft, In the first communication portion, the second conveying screw has a second paddle that is a protruding member protruding from a peripheral surface of the second rotating shaft and extending along an axial direction of the second rotating shaft, The developer is sent from the first storage chamber through the first communicating portion to the second storage chamber, and is sent from the second storage chamber through the second communicating portion to the first storage chamber, thereby circulating within the developer tank.

2. 2. The developing device according to claim 1, wherein the first conveying screw and the second conveying screw rotate at the same rotational speed.

3. the first conveying screw rotates in a direction in which the first paddle moves from a bottom surface side of the first communication portion toward the second paddle, 2. The developing device according to claim 1, wherein the second conveying screw rotates in a direction opposite to that of the first conveying screw.

4. The second rotation shaft is disposed at a higher position than the first rotation shaft, The developing device according to claim 1 , wherein a bottom surface of the first communication portion is an upwardly inclined surface extending from a position where the first paddle is located to a position where the second paddle is located.

5. the first conveying screw conveys the developer in a first direction, 2. The developing device according to claim 1, wherein the first paddle is twisted in a direction opposite to a rotation direction of the first rotary shaft as the first paddle advances in the first direction.

6. the second conveying screw conveys the developer in a second direction, 2. The developing device according to claim 1, wherein the second paddle is twisted in a direction opposite to a rotation direction of the second rotary shaft as the second paddle advances in the second direction.

7. The developing device according to claim 1 , wherein each of the first and second helical blades is a double-bladed blade.

8. The developing device according to claim 1 , wherein a portion of the second spiral blade is provided inside the first communication portion.

9. the first paddle has a first end side on a tip side protruding from a circumferential surface of the first rotating shaft, the second paddle has a second end side on a tip side protruding from a circumferential surface of the second rotating shaft, The developing device according to claim 1 , wherein the first conveying screw and the second conveying screw rotate so that the first end side and the second end side do not face each other.

10. Each of the first paddle and the second paddle includes two of the protruding members, 2. The developing device according to claim 1, wherein the two protruding members are provided at intervals of 180 degrees along the circumference of the first rotating shaft and the circumference of the second rotating shaft.

11. Each of the first paddle and the second paddle includes three of the protruding members, 2. The developing device according to claim 1, wherein the three protruding members are provided at intervals of 120 degrees along the circumference of the first rotating shaft and the circumference of the second rotating shaft.

12. An image forming apparatus comprising the developing device according to claim 1 .

Images