Image forming apparatus and developing device

Abstract

To provide an image forming apparatus and a developing device that can improve the accuracy of detecting the amount of toner in developer.SOLUTION: An image forming apparatus 100 comprises a developing device 2 having a developer tank 211, a first screw-shaped conveying member 212, a developer carrier (214), and a toner amount detection part 219, and the developer tank 211 is provided with an opening 211a at a position at an end on the upstream side in a first conveyance direction S1 and above the first screw-shaped conveying member 212. The image forming apparatus 100 includes a guide part 220 that is provided with a guide path 221 for guiding a toner received from a receiving port 220a for receiving toner to the opening 211a in the developer tank 211, and the guide path 221 has an inclined surface 221a that is inclined with respect to a vertical direction Z to allow the toner received from the receiving port 220a to fall.SELECTED DRAWING: Figure 9

Description

[Technical Field]

[0001] The present disclosure relates to an image forming apparatus such as a copier, a multifunction machine, a printer, or a facsimile machine, and a developing device. [Background technology]

[0002] In a conventional image forming apparatus, for example, in a developing device, a developer containing toner is stored in a long developer tank, the developer stored in the developer tank is transported by a screw-shaped transport member in a predetermined transport direction on one side in the longitudinal direction of the developer tank, the developer is carried by a developer carrier (for example, a developing roller), and the amount of toner contained in the developer is detected by a toner amount detector. In the developing device, when the toner in the developer is consumed and the amount of toner in the developer detected by the toner amount detector becomes less than a reference toner amount, toner is replenished to the developer tank.

[0003] Specifically, the developer tank has an opening above the screw-shaped transport member at the upstream end in the transport direction of the developer transported by the screw-shaped transport member. The image forming apparatus has a guide section provided with a guide path that guides the toner received through the toner receiving port to the opening in the developer tank.

[0004] For example, Patent Document 1 describes an image forming apparatus in which a guide path (toner transfer mechanism) along the vertical direction guides toner received from a receiving port to an opening (toner supply port) in a developing tank. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-2771 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in such conventional image forming apparatuses, because the guide path is vertical, if the toner aggregates, the aggregated toner is replenished to the developer tank as is, and the toner amount detector detects the toner amount of the developer containing the aggregated toner. This results in an increase in overshoots that exceed the allowable range of the detected value detected by the toner amount detector, and accordingly, the accuracy of detecting the toner amount in the developer deteriorates.

[0007] Therefore, an object of the present disclosure is to provide an image forming apparatus and a developing device that can improve the accuracy of detecting the amount of toner in a developer. [Means for solving the problem]

[0008] In order to solve the above problem, the image forming apparatus of the present disclosure comprises a developing device having a long developing tank that contains developer including toner, a first screw-shaped transport member that transports the developer contained in the developing tank in a predetermined first transport direction on one side of the longitudinal direction of the developing tank, a developer carrier that carries the developer contained in the developing tank, and a toner amount detection unit that detects the amount of toner contained in the developer contained in the developing tank, wherein the developing tank has an opening at a position above the first screw-shaped transport member at its upstream end in the first transport direction, and the image forming apparatus comprises a guide unit that has a guide path that guides the toner received from a receiving port that receives the toner to the opening in the developing tank, and the guide path has an inclined surface that is inclined in the vertical direction and onto which the toner received from the receiving port falls.

[0009] In addition, the developing device according to the present disclosure comprises a long developing tank that contains developer including toner, a first screw-shaped transport member that transports the developer contained in the developing tank in a predetermined first transport direction on one side of the longitudinal direction of the developing tank, a developer carrier that carries the developer contained in the developing tank, and a toner amount detection unit that detects the amount of toner contained in the developer contained in the developing tank, wherein the developing tank has an opening at a position above the first screw-shaped transport member at the upstream end in the first transport direction, and the developing device is equipped with a guide unit that has a guide path that guides the toner received from a receiving port that receives the toner to the opening in the developing tank, and the guide path has an inclined surface that is inclined in the vertical direction and along which the toner received from the receiving port falls. [Effects of the Invention]

[0010] According to the present disclosure, it is possible to improve the accuracy of detecting the amount of toner in the developer. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a cross-sectional view showing an example of the overall configuration of an image forming apparatus according to an embodiment of the present invention; [Figure 2A] 2 is a perspective view showing an example of a toner storage unit, a guide unit, and a developing device according to the first embodiment. FIG. [Figure 2B] FIG. 2 is an exploded perspective view showing an example of a toner storage unit, a guide unit, and a developing device according to the first embodiment. [Figure 3A] 2C is a cross-sectional view showing the toner storage section, the guide section, and the developing device shown in FIGS. 2A and 2B. FIG. [Figure 3B] 3B is a plan view schematically showing a portion of the developing device shown in FIG. 3A including a first screw-shaped conveying member and a second screw-shaped conveying member. FIG. [Figure 4A] FIG. 3C is a cross-sectional view showing an example of the toner amount detection unit shown in FIGS. 3A and 3B. [Figure 4B] FIG. 2 is a schematic diagram showing the state of toner and carrier in a developer contained in a developer tank. [Figure 5A] FIG. 3B is a cross-sectional view taken along line AA shown in FIG. 3A. [Figure 5B] FIG. 3B is a cross-sectional view taken along line BB shown in FIG. 3A. [Figure 6] 10 is a schematic diagram showing how toner received through a receiving opening of a guide portion falls toward an inclined surface and collides with the inclined surface. FIG. [Figure 7] FIG. 10 is a cross-sectional view of an example of a developing device and a photosensitive drum according to a second embodiment. [Figure 8A] FIG. 8 is a perspective view including a partial cross section of the developing device shown in FIG. [Figure 8B] 8 is a cross-sectional view of the developing device shown in FIG. 7 as viewed from above. [Figure 8C] 8 is a cross-sectional view of the developing device shown in FIG. 7, seen from the side opposite to the developing roller. [Figure 9] 8 is a cross-sectional view showing the positional relationship between a guide portion that receives toner and a first screw-shaped conveying member in the developing device shown in FIG. 7. FIG. [Figure 10] 10 is a graph showing a comparison of the detection value of the toner amount detection unit when the guide unit according to the present embodiment is used with the detection value of the toner amount detection unit when a conventional guide unit having a guide path along the vertical direction is used. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the following description, the same components are denoted by the same reference numerals. The names and functions of the components are also the same. Therefore, detailed descriptions thereof will not be repeated.

[0013] [Configuration of image forming device] 1 is a cross-sectional view showing an example of the overall configuration of an image forming apparatus 100 according to the present embodiment. In the drawing, the symbol X indicates the left-right direction, and the symbols X1 and X2 respectively indicate The symbols Y and Y2 indicate the front side (front face, operation side) and rear side (rear face), respectively. The symbol Z indicates the up and down direction.

[0014] The image forming apparatus 100 forms a multicolor or monochrome image on a recording sheet P such as a recording paper in accordance with image data transmitted from an external device.

[0015] 1, in this embodiment, a full-color printer is used as the image forming apparatus 100. However, the image forming apparatus 100 may also be a copier, a facsimile machine, or a multifunction machine equipped with these functions that can form a multicolor or monochrome image on a recording sheet P in accordance with image data transmitted from an external device and / or image data read from an original by a scanner. The image forming apparatus 100 may also be a monochrome image forming apparatus 100.

[0016] Image forming apparatus 100 includes a plurality of (four in this example) photosensitive drums 3a-3d (an example of image carriers), a plurality of chargers 5a-5d (charging devices), a laser scanner unit 1 (exposure device), a plurality of developing devices 2a-2d, an intermediate transfer device 70, a transfer roller 11, cleaner units 4a-4d (cleaning devices), a paper feed tray 10, a pickup roller 16, transport rollers 17a and 17b, a fixing device 12, a registration roller 18, a discharge roller 19, and a paper discharge tray 15. Developing devices 2a-2d and toner containers 9a-9d (toner cartridges) are removably mounted in a main body 110 of image forming apparatus 100.

[0017] The chargers 5a to 5d charge the surfaces of the photosensitive drums 3a to 3d to a predetermined potential (for example, -550 V). In this example, the chargers 5a to 5d are charging rollers. The laser scanner unit 1 irradiates the charged surfaces of the photosensitive drums 3a to 3d with laser light to form electrostatic latent images. The developing devices 2a to 2d each have a developer tank 211 that individually contains four colors of developer: black, cyan, magenta, and yellow. The developing devices 2a to 2d develop the electrostatic latent images on the surfaces of the photosensitive drums 3a to 3d using the developer contained in the developer tank 211 to form toner images. The toner containers 9a to 9d individually supply toner of four colors: black, cyan, magenta, and yellow, to the developer tanks 211 in the developing devices 2a to 2d.

[0018] The intermediate transfer device 70 includes an intermediate transfer belt 7, intermediate transfer rollers 6a to 6d, an intermediate transfer belt drive roller 71, and an intermediate transfer belt driven roller 72. The intermediate transfer rollers 6a to 6d, the intermediate transfer belt drive roller 71, and the intermediate transfer belt driven roller 72 tension the intermediate transfer belt 7 and rotate the intermediate transfer belt 7 in a predetermined rotation direction B. The intermediate transfer rollers 6a to 6d transfer the toner images on the surfaces of the photosensitive drums 3a to 3d onto the surface of the intermediate transfer belt 7.

[0019] Transfer roller 11 transfers the toner image on the surface of intermediate transfer belt 7 onto recording sheet P. Cleaner units 4a to 4d remove residual toner remaining on the surfaces of photosensitive drums 3a to 3d after the toner image has been transferred to intermediate transfer belt 7.

[0020] The paper feed tray 10 stores recording sheets P. The pickup roller 16 pulls out the recording sheets P stored in the paper feed tray 10 toward the transport roller 17a. The transport roller 17a transports the recording sheets P pulled out by the pickup roller 16 to the registration roller 18. The registration roller 18 transports the recording sheets P transported by the transport roller 17a toward the transfer nip between the transfer roller 11 and the intermediate transfer belt 7. The fixing device 12 fixes the toner image transferred onto the recording sheets P. The transport rollers 17b, 1 7b transports the recording sheet P from the fixing device 12 toward the discharge rollers 19. The discharge rollers 19 discharge the recording sheet P transported by the transport rollers 17b, 17b to the outside of the main body 110 of the image forming apparatus 100. The paper discharge tray 15 holds the recording sheet P discharged by the discharge rollers 19.

[0021] Here, the symbol a indicates a member for forming a black image, the symbol b indicates a member for forming a cyan image, the symbol c indicates a member for forming a magenta image, and the symbol d indicates a member for forming a yellow image.

[0022] In this example, in the image forming apparatus 100, a black toner image, a cyan toner image, a magenta toner image, and a yellow toner image are selectively formed on the surfaces of the photosensitive drums 3a to 3d based on image data for each of the four color components, black (K), cyan (C), magenta (M), and yellow (Y). Then, these formed toner images are superimposed on the intermediate transfer belt 7, and one color image is formed on the recording sheet P.

[0023] Since the photosensitive drums 3a to 3d corresponding to each color have the same configuration, the following description will unify them by the reference numeral 3. Similarly, the developing devices 2a to 2d will be unified by the reference numeral 2, and the toner storage units 9a to 9d will be unified by the reference numeral 9.

[0024] (About this embodiment) 2A and 2B are a perspective view and an exploded perspective view, respectively, showing an example of the toner storage unit 9, the guide unit 220, and the developing device 2 according to the first embodiment. FIG. 3A is a cross-sectional view showing the toner storage unit 9, the guide unit 220, and the developing device 2 shown in FIGS. 2A and 2B. FIG. 3B is a plan view schematically showing the first screw-shaped transport member 212 and the second screw-shaped transport member 213 of the developing device 2 shown in FIG. 3A. FIG. 4A is a cross-sectional view showing an example of the toner amount detection unit 219 shown in FIGS. 3A and 3B. FIG. 4B is a schematic diagram showing the state of the toner T and the carrier C in the developer D stored in the developer tank 211. FIG. 5A is a cross-sectional view taken along line AA in FIG. 3A. FIG. 5B is a cross-sectional view taken along line BB in FIG. 3A. Note that in these figures, the toner T in the toner storage unit 9 and the guide unit 220, and the developer D in the developer tank 211 are omitted. FIG. 6 is a schematic diagram showing how toner T received through receiving port 220a of guide portion 220 falls toward inclined surface 221a and collides with inclined surface 221a.

[0025] [Toner storage compartment] The toner storage unit 9 includes a toner storage unit main body 91 (specifically, a toner storage container), an upper cover 92, a toner stirring member 93 (see FIG. 5A), and a screw-shaped transport member 94 (see FIGS. 3A and 5A).

[0026] The toner storage unit main body 91 stores toner T. The top cover 92 is provided on the top of the toner storage unit main body 91. The toner agitator 93 is rotationally driven by a rotation drive unit 95 (drive motor) (see FIG. 2A) and agitates the toner T stored in the toner storage unit main body 91 while sending it to the screw-shaped transport member 94. As shown in FIG. 5A, the toner agitator 93 has a first rotating shaft 93a and a first agitator 93b. The first agitator 93b is film-shaped and is provided on the first rotating shaft 93a. The toner agitator 93 agitates the toner T as the first rotating shaft 93a and the first agitator 93b rotate. The first rotating shaft 93a is supported by the toner storage unit main body 91 so as to be rotatable about a rotation axis that extends along the longitudinal direction E of the developer tank 211 (in this example, the front-rear direction Y). The screw-shaped conveying member 94 is rotated by a rotation drive unit 95 (drive motor) and conveys the toner T sent out from the toner agitator 93 toward the toner supply port 91a that communicates with the receiving port 220a of the guide unit 220. As a result, the screw-shaped conveying member 94 conveys the toner T contained in the toner containing unit main body 91. The toner T can be supplied from the toner supply port 91 a to the receiving port 220 a of the guide portion 220 .

[0027] [Developing device] The developing device 2 includes a long developing tank 211, a first screw-shaped transport member 212, a developing roller 214 (an example of a developer carrier), a toner amount detecting section 219, and a guide section 220.

[0028] Developing tank 211 contains developer D (see FIG. 4B ) including toner T. First screw-shaped transport member 212 is disposed parallel to developing roller 214. First screw-shaped transport member 212 rotates about a first rotation axis α to transport developer D contained in developing tank 211 in a predetermined first transport direction S1 to one side E1 (front side) in the longitudinal direction E of developing tank 211. Developing roller 214 carries developer D contained in developing tank 211. Toner amount detection unit 219 detects the amount of toner contained in developer D contained in developing tank 211.

[0029] More specifically, the developing device 2 has a developing roller 214 disposed in a developing tank 211 so as to face the photosensitive drum 3 (see FIGS. 1 and 5A). The developing roller 214 supplies toner T to the photosensitive drum 3. That is, the developing device 2 supplies toner T to the surface of the photosensitive drum 3 by the developing roller 214, thereby developing (visualizing) the electrostatic latent image formed on the surface of the photosensitive drum 3.

[0030] <Second screw-shaped conveying member> Developing device 2 further includes second screw-shaped transport member 213 (see FIGS. 3B, 5A, and 5B). Second screw-shaped transport member 213 rotates about second rotation axis β to transport developer D contained in developer tank 211 in a predetermined second transport direction S2 toward the other side E2 (rear side, back surface side) in the longitudinal direction E of developer tank 211. Second screw-shaped transport member 213 supplies developer D to developing roller 214.

[0031] <Developer tank> Developing tank 211 contains developer D (two-component developer) containing toner T and carrier C (magnetic carrier, for example, ferrite carrier). Inside developing tank 211, a first screw-shaped transport member 212, a second screw-shaped transport member 213, a developing roller 214, and a doctor blade 216 are arranged.

[0032] Developing tank 211 is provided with first chamber 201, second chamber 202, and first communication portion 201a. A first screw-shaped transport member 212 is disposed in first chamber 201. A second screw-shaped transport member 213 is disposed in second chamber 202. First communication portion 201a communicates first chamber 201 with second chamber 202 on the downstream side of developing tank 211 in first transport direction S1. Developing roller 214 carries developer D transported by second screw-shaped transport member 213. First communication portion 201a communicates first chamber 201 with second chamber 202 on the downstream end of developing tank 211 in first transport direction S1, and guides developer D transported by first screw-shaped transport member 212 from first chamber 201 to second chamber 202.

[0033] More specifically, the developing tank 211 is provided with a partition wall 217 (partition plate). The interior of the developing tank 211 is divided by the partition wall 217 into a first chamber 201 and a second chamber 202 adjacent to each other in the widthwise direction F of the developing tank 211 (in this example, the left-right direction X). That is, the partition wall 217 divides the developing tank 211 into the first chamber 201 and the second chamber 202 by dividing the central portion in the widthwise direction F along the longitudinal direction E. In this example, the first chamber 201 and the second chamber 202 are formed in an arc shape in cross section as seen from the direction of the rotation axes of the first screw-shaped transport member 212 and the second screw-shaped transport member 213 (the longitudinal direction E, in this example, the front-rear direction Y) (see Figure 1). 5A). In the developing tank 211, a first screw-shaped transport member 212 and a second screw-shaped transport member 213 are rotatably provided in the first chamber 201 and the second chamber 202, respectively. The second screw-shaped transport member 213 is disposed parallel to the developing roller 214 and is located below the developing roller 214.

[0034] Opening 211a (toner supply port) is provided in top plate 215 at the upstream end of first chamber 201 of developer tank 211 in first transport direction S1. Opening 211a is provided above first screw-shaped transport member 212. Toner T discharged from toner storage section 9 is supplied to developer tank 211 through opening 211a in developing device 2. Here, toner T stored in toner storage section 9 may contain carrier C to compensate for carrier C reduced in developer tank 211 by development.

[0035] Both ends of first chamber 201 and second chamber 202 in the longitudinal direction E are communicated with each other by first communication portion 201a (see FIG. 3B) and second communication portion 202a (see FIG. 3B). First communication portion 201a communicates first chamber 201 with second chamber 202 at the downstream end of developer tank 211 in first transport direction S1, and guides developer D transported by first screw-shaped transport member 212 from first chamber 201 to second chamber 202. Second communication portion 202a communicates second chamber 202 with first chamber 201 at the downstream end of developer tank 211 in second transport direction S2, and guides developer D transported by second screw-shaped transport member 213 from second chamber 202 to first chamber 201. The developing device 2 is configured to be able to transport and circulate developer D in a developer tank 211 through a circular developer transport path formed by the first chamber 201, the first communicating portion 201a, the second chamber 202, and the second communicating portion 202a.

[0036] More specifically, in the developing tank 211, in the first chamber 201, the developer D is transported in the first transport direction S1 (Y1) by the first screw-shaped transport member 212, and in the first communicating portion 201a, the developer D is transported to the other side F2 (the second screw-shaped transport member 213 side, in this example, the right side X2) in the short direction F. In the second chamber 202, the developer D is transported in the second transport direction S2 (Y2) by the second screw-shaped transport member 213, and in the second communicating portion 202a, the developer D is transported to one side F1 (the first screw-shaped transport member 212 side, in this example, the left side X1) in the short direction F.

[0037] The first screw-shaped conveying member 212 has a first rotating shaft 212a and a first helical blade 212b. The first screw-shaped conveying member 212 rotates in a first rotation direction R1 in which the first helical blade 212b faces the second screw-shaped conveying member 213 from below. The second screw-shaped conveying member 213 has a second rotating shaft 213a and a second helical blade 213b. The second screw-shaped conveying member 213 rotates in a second rotation direction R2 in which the second helical blade 213b faces the first screw-shaped conveying member 212 from below.

[0038] The first screw-shaped transport member 212 and the second screw-shaped transport member 213 are rotated by a rotation drive unit (drive motor) not shown, and transport the developer D in the first chamber 201 and the second chamber 202 in the longitudinal direction E while stirring it.

[0039] In the developing tank 211, the developer D is transported while being stirred by the first screw-shaped transport member 212 and the second screw-shaped transport member 213, and the toner T is charged to a predetermined charge polarity (negative polarity in this example), and the developer D in the second chamber 202 is carried on the surface of the developing roller 214 by the second screw-shaped transport member 213.

[0040] <Developing roller> As shown in Figure 5A, developer tank 211 has an opening OP formed above second chamber 202, and developing roller 214 is rotatably disposed at the position of opening OP. The developing roller 214 has a developing sleeve 214a, and the developing sleeve 214a carries the developer D in the second chamber 202. The developing sleeve 214a is fixed to the developer tank 211 and driven to rotate around a magnet (not shown) having multiple magnetic poles in a circumferential direction in a first rotation direction R1 about a rotation axis δ by a driving means (not shown), and the developing roller 214 is driven to rotate in a second rotation direction R2 about a rotation axis γ. A predetermined developing nip is formed between the developing roller 214 and the photosensitive drum 3. A predetermined developing bias (e.g., −400 V) is applied to the developing roller 214 from a power supply (not shown). As a result, toner is supplied from the developing roller 214 carrying the developer D in the second chamber 202 to the photosensitive drum 3, and the toner T is attached to the electrostatic latent image on the surface of the photosensitive drum 3, thereby developing the electrostatic latent image.

[0041] <Doctor Blade> 5A, the developing device 2 further includes a doctor blade 216 that regulates the developer D carried on the developing roller 214. The doctor blade 216 is a rectangular plate-like member that extends along the rotational axis direction (longitudinal direction E) of the developing roller 214. The doctor blade 216 is fixed to the lower edge of the opening OP of the developing tank 211 with an upper end 216a thereof maintaining a predetermined gap from the surface of the developing roller 214.

[0042] <Toner amount detection unit> Toner amount detection unit 219 is a magnetic permeability sensor (toner concentration sensor) that detects the magnetic permeability of developer D, which increases or decreases in accordance with a change in the ratio of toner T to developer D, which is composed of carrier C (magnetic material such as iron or ferrite) and toner T (non-magnetic material). Toner amount detection unit 219 is provided downstream of opening 211a in first transport direction S1 of developer tank 211 (first chamber 201). Toner amount detection unit 219 is provided so that detection surface 219a is exposed inside first chamber 201 at a position where it contacts developer D in first chamber 201. That is, toner amount detection unit 219 is provided on the outer surface of the bottom of first chamber 201, and detection surface 219a faces first screw-shaped transport member 212 in developer tank 211. Toner amount detection unit 219 is electrically connected to an input system of a control unit (not shown). This allows the control unit to detect the ratio of toner T to the entire amount of developer D in developer tank 211 based on the detection result of toner amount detection unit 219. In other words, the ratio (weight ratio or volume ratio) of toner T to developer D can be detected from the detection result of toner amount detection unit 219 using a conversion formula or conversion table that has been set in advance.

[0043] The particle diameter of the toner T can be exemplified as approximately 5 μm to 8 μm, and the particle diameter of the carrier C can be exemplified as approximately 40 μm to 50 μm. The amount of toner contained in the developer D (for example, the weight ratio of the toner T to the developer D (so-called T / D): (weight of the toner T) / (weight of the developer D)) can be exemplified as approximately 6% to 8%. For example, the developer D is controlled by the toner amount detection unit 219 so that the weight ratio of the toner T is approximately 7%.

[0044] [First embodiment] The developer tank 211 has an opening 211a at an end on the upstream side (rear side Y2 in this example) in the first transport direction S1, above the first screw-shaped transport member 212. The opening 211a overlaps (intersects with) the rotation axis of the first screw-shaped transport member 212 in a plan view seen from above.

[0045] Guide section 220 is provided with guide path 221. Guide path 221 guides toner T received from receiving port 220a (see FIGS. 2B, 3A, and 5B) that receives toner T to opening 211a in developer tank 211. Also, guide path 221 has discharge port 220b (see FIGS. 3A and 5B) that discharges toner T, facing opening 211a. Here, as a mode in which receiving port 220a receives toner T, in addition to a mode in which toner T sent from toner storage section 9 is directly received as in the present embodiment, there are other modes in which toner T is received by receiving port 220a. An example of such a configuration is that the toner is received through a toner transport path including a screw-shaped transport member (not shown).

[0046] Incidentally, in a conventional image forming apparatus in which the guide path runs vertically, if the toner aggregates, the aggregated toner is replenished as is to the developer tank, and the toner amount detection unit detects the toner amount of developer D containing the aggregated toner. This results in an increase in overshoots that exceed the allowable range of the detection value detected by the toner amount detection unit, and accordingly, the detection accuracy of the toner amount in developer D deteriorates.

[0047] In this regard, in the present embodiment, the guide path 221 has an inclined surface 221a (see FIG. 5B) that is inclined with respect to the vertical direction Z and onto which the toner T received from the receiving port 220a falls. In this example, the inclined surface 221a is provided in the guide section 220 so that a virtual extension line ρ (see FIG. 5B) to the downward side passes through the first spiral blade 212b on the inclined side of the first screw-shaped conveying member 212.

[0048] 6, in the present embodiment, toner T received through receiving port 220a of guide unit 220 falls toward inclined surface 221a inclined with respect to vertical direction Z in guide path 221 and collides with inclined surface 221a. Even if toner T is aggregated, the aggregated clumps of toner T that collide with inclined surface 221a can be loosened by inclined surface 221a, and the toner T can be guided toward opening 211a. As a result, toner T loosened by inclined surface 221a can be replenished to developer tank 211 through opening 211a. Therefore, it is possible to reduce or eliminate overshoot that exceeds the allowable range of the detection value detected by toner amount detection unit 219, thereby improving the detection accuracy of the toner amount in developer D.

[0049] The inclination angle θ of the inclined surface 221a with respect to the up-down direction Z (see FIG. 5B) may be any angle that allows the toner T received through the receiving port 220a to fall onto the inclined surface 221a and be guided to the opening 211a. The inclination angle θ can be, for example, from 10 degrees to 60 degrees, and more preferably from 20 degrees to 45 degrees. If the inclination angle θ is less than 10 degrees, it becomes difficult for the inclined surface 221a to break up clumps of toner T that have fallen onto the inclined surface 221a. On the other hand, if the inclination angle θ exceeds 60 degrees, it becomes difficult for the toner T that has fallen onto the inclined surface 221a to move toward the opening 211a.

[0050] [First embodiment-1] 5B, in the present embodiment, receiving opening 220a is positioned at a position offset from opening 211a so as not to overlap (intersect) with first rotation axis α of first screw-shaped transport member 212. More specifically, receiving opening 220a is offset from opening 211a to the other side F2 in the short-side direction F (toward photosensitive drum 3 with respect to first rotation axis α in this example) in a plan view seen from above. Incoming opening 220a is offset by a predetermined offset distance d from first rotation axis α of first screw-shaped transport member 212 in the short-side direction F of developer tank 211.

[0051] With this configuration, the toner T received through the receiving port 220a can be reliably dropped onto the inclined surface 221a. This increases the amount of toner T that can be broken up by the inclined surface 221a, thereby improving the accuracy of detecting the amount of toner in the developer D.

[0052] [First embodiment-2] The inclined surface 221a is inclined so as to approach an imaginary straight line λ (see FIG. 5B) that passes through the first rotation axis α of the first screw-shaped transport member 212 and that extends in the vertical direction Z, as it goes downward when viewed from the longitudinal direction E of the developing tank 211. In other words, the inclined surface 221a, in a plan view viewed from above, goes downward from the end of the receiving port 220a that is farther from the first rotation axis α. Therefore, it is inclined so that the distance from the first rotation axis α becomes smaller.

[0053] With this configuration, the toner T received through the receiving port 220a can be guided along the inclined surface 221a to the first screw-shaped conveying member 212. This increases the amount of toner T that can be broken up by the inclined surface 221a, thereby improving the accuracy of detecting the amount of toner in the developer D.

[0054] [First embodiment-3] The first screw-shaped conveying member 212 is driven to rotate from below to above on the side where the receiving port 220a is offset from the opening 211a (on the side of the second screw-shaped conveying member 213 in this example).

[0055] In this configuration, the toner T transported along the inclined surface 221a of the guide path 221 is pushed upward by the first screw-shaped transport member 212, which is rotated from below to above on the offset side, and can be transported in the first transport direction S1 while breaking up clumps of the toner T. This makes it possible to effectively break up clumps of the toner T between the first screw-shaped transport member 212 and the opposing portion 221b (see FIG. 5B ) of the guide path 221 facing the first screw-shaped transport member 212 on the upstream side in the first rotation direction R1, and thus improves the accuracy of detecting the amount of toner in the developer D.

[0056] [First embodiment-4] As shown in FIG. 5B, opening 211a is provided in developing tank 211 so that end position P1 (in this example, the lower end of inclined surface 221a) on the side where receiving port 220a is offset from opening 211a is located between outer diameter position P2 of the offset side (in this example, the other side F2) of first rotating shaft portion 212a in the short direction F of developing tank 211 and outer diameter position P3 of the offset side (in this example, the other side F2) of first spiral blade 212b in the short direction F.

[0057] In this configuration, the toner T conveyed along the inclined surface 221a of the guide path 221 can be reliably guided to the first screw-shaped conveying member 212. This improves the accuracy of detecting the amount of toner in the developer D.

[0058] [First embodiment-5] Incidentally, first communication portion 201a, which connects first chamber 201 and second chamber 202 at the downstream end of developer tank 211 in first transport direction S1, guides developer D transported by first screw-shaped transport member 212 from first chamber 201 to second chamber 202, so developer D tends to accumulate in first communication portion 201a (see accumulation point ε in FIG. 3B ), which in turn tends to increase the bulk density of developer D. For this reason, if toner amount detection portion 219 is provided near the downstream end of first chamber 201 in first transport direction S1, it becomes difficult for toner amount detection portion 219 to output the actual detected value, which in turn deteriorates the detection accuracy of the toner amount in developer D.

[0059] On the other hand, when toner amount detection unit 219 is provided near the upstream end of first chamber 201 in first transport direction S1, if toner T aggregates, the detection value detected by toner amount detection unit 219 will overshoot beyond the allowable range, thereby deteriorating the detection accuracy of the toner amount in developer D. However, in this embodiment, toner T received through receiving port 220a falls onto inclined surface 221a. As a result, even if toner amount detection unit 219 is provided near the upstream end of first chamber 201 in first transport direction S1, for example, even if toner amount detection unit 219 is provided on the opening 211a side of the midpoint M between opening 211a and first communicating portion 201a in first chamber 201, toner T loosened by inclined surface 221a can be replenished to developer tank 211 through opening 211a. Therefore, the overshoot beyond the allowable range of the detection value detected by toner amount detection unit 219 can be reduced or This can eliminate the problem, and in turn can prevent the accuracy of detecting the amount of toner in the developer D from deteriorating.

[0060] [First embodiment-6] The first chamber 201 and the second chamber 202 are provided in the developing tank 211 so that the second position Q2 (see FIG. 5B), which is the lowest position of the bottom of the second chamber 202, is located higher than the first position Q1 (see FIG. 5B), which is the lowest position of the bottom of the first chamber 201. The first screw-shaped transport member 212 and the second screw-shaped transport member 213 are provided so that the second rotation axis β of the second screw-shaped transport member 213 is located higher than the first rotation axis α of the first screw-shaped transport member 212.

[0061] In this configuration, the distance e (see FIG. 5B) between the first rotation axis α of the first screw-shaped transport member 212 and the second rotation axis β of the second screw-shaped transport member 213 in the short side direction F can be made shorter than when the first screw-shaped transport member 212 and the second screw-shaped transport member 213 are arranged side by side at the same height. This makes it possible to make the developer tank 211, and ultimately the developing device 2, more compact in the short side direction F.

[0062] Incidentally, if second position Q2 of the bottom of second chamber 202 were higher than first position Q1 of the bottom of first chamber 201, as in the present embodiment, first screw-shaped transport member 212 would push developer D up from first chamber 201 toward second chamber 202, making it more likely for developer D to accumulate in first communicating portion 201a, thereby further increasing the bulk density of developer D and thus deteriorating the accuracy of detecting the toner amount in developer D. However, in the present embodiment, toner amount detecting portion 219 has detection surface 219a provided on the opening 211a side of intermediate position M between opening 211a and first communicating portion 201a in first chamber 201. This makes it possible to suppress deterioration in the accuracy of detecting the toner amount in developer D, which is caused by the bulk density of developer D.

[0063] On the other hand, when toner amount detection unit 219 is provided closer to opening 211a than intermediate position M, if toner T aggregates, the detection value detected by the toner amount detection unit will overshoot beyond the allowable range more frequently, which will deteriorate the accuracy of detecting the toner amount in developer D. However, in this embodiment, toner T received through receiving port 220a falls onto inclined surface 221a. This makes it possible to prevent deterioration in the accuracy of detecting the toner amount in developer D due to aggregation of toner T.

[0064] [First embodiment-7] The guide section 220 is provided in the main body 110 of the image forming apparatus 100, and the developing device 2 is detachably attached to the main body 110 of the image forming apparatus 100.

[0065] More specifically, opening 211a is provided on the other side E2 (rear side Y2 in this example) of developing tank 211 in the longitudinal direction E, and guide section 220 is provided on rear side Y2 (back side) of main body 110 of image forming apparatus 100. When developing device 2 is attached to main body 110 of image forming apparatus 100, opening 211a of developing tank 211 communicates with receiving port 220a of guide section 220 in main body 110 of image forming apparatus 100.

[0066] In this configuration, the developing device 2 can be attached to and detached from the main body 110 of the image forming apparatus 100 without providing the guide portion 220 to the developing device 2. This improves the ease of attaching and detaching the developing device 2 to and from the main body of the image forming apparatus.

[0067] Second Embodiment FIG. 7 is a cross-sectional view of an example of the developing device 2 and the photosensitive drum 3 according to the second embodiment. FIG. 8A is a perspective view including a partial cross section of the developing device 2 shown in FIG. 7. The interior 220 is shown in cross section. Fig. 8B is a cross-sectional view of the developing device 2 shown in Fig. 7 viewed from above. Fig. 8C is a cross-sectional view of the developing device 2 shown in Fig. 7 viewed from the side opposite the developing roller 214. Fig. 9 is a cross-sectional view showing the positional relationship between the guide portion 220 that receives the toner T and the first screw-shaped transport member 212 in the developing device 2 shown in Fig. 7.

[0068] In the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted.

[0069] In the first embodiment, opening 211a is provided on the other side E2 (Y2) in the longitudinal direction E of developer tank 211, first screw-shaped transport member 212 is positioned on the opposite side from photosensitive drum 3 with respect to developing roller 214, and inclined surface 221a of guide path 221 in guide section 220 is inclined toward photosensitive drum 3 (F2). In contrast, in the second embodiment, opening 211a is provided on one side E1 (Y1) in the longitudinal direction E of developer tank 211, first screw-shaped transport member 212 is positioned on the photosensitive drum 3 side with respect to developing roller 214, and inclined surface 221a of guide path 221 in guide section 220 is inclined toward the opposite side (F1) from photosensitive drum 3. The following explanation will focus on the differences from the first embodiment.

[0070] 8A and 9, the first screw-shaped transport member 212 is rotated about the first rotation axis α to transport the developer D contained in the developer tank 211 in the second transport direction S2 (Y2). The second screw-shaped transport member 213 is rotated about the second rotation axis β to transport the developer D contained in the developer tank 211 in the first transport direction S1 (Y1).

[0071] An opening 211a (toner supply port) is provided in top plate 215 at the upstream end of first chamber 201 of developer tank 211 in second transport direction S2. Opening 211a is provided above first screw-shaped transport member 212. Toner T discharged from toner storage section 9 is supplied to developer tank 211 in developing device 2 through opening 211a.

[0072] Both ends of first chamber 201 and second chamber 202 in the longitudinal direction E are communicated with each other by first communication portion 201a (see FIGS. 8B and 8C) and second communication portion 202a (see FIG. 8B). First communication portion 201a communicates first chamber 201 with second chamber 202 at the downstream end of developer tank 211 in second transport direction S2, and guides developer D transported by first screw-shaped transport member 212 from first chamber 201 to second chamber 202. Second communication portion 202a communicates second chamber 202 with first chamber 201 at the downstream end of developer tank 211 in first transport direction S1, and guides developer D transported by second screw-shaped transport member 213 from second chamber 202 to first chamber 201. The developing device 2 is configured to be able to transport and circulate developer D in a developer tank 211 through a circular developer transport path formed by the first chamber 201, the first communicating portion 201a, the second chamber 202, and the second communicating portion 202a.

[0073] More specifically, in the developing tank 211, in the first chamber 201, the developer D is transported in the second transport direction S2 (Y2) by the first screw-shaped transport member 212, and in the first communicating portion 201a, the developer D is transported to one side F1 in the short direction F (the second screw-shaped transport member 213 side, in this example, the left side X1). In the second chamber 202, the developer D is transported in the first transport direction S1 (Y1) by the second screw-shaped transport member 213, and in the second communicating portion 202a, the developer D is transported to the other side F2 in the short direction F (the first screw-shaped transport member 212 side, in this example, the right side X2).

[0074] The first screw-shaped conveying member 212 rotates in a second rotation direction R2 in which the first spiral blade 212b faces the second screw-shaped conveying member 213 from below. The first rotating shaft 212a has a detection surface 219a in the toner amount detection unit 219, on which agitating pieces 212b1 (ribs) (see FIG. 8C) are provided. This allows the agitating piece 212b1 to level the toner clumps.

[0075] The second screw-shaped conveying member 213 rotates in a first rotation direction R1 in which the second spiral blade 213b faces the first screw-shaped conveying member 212 side from below.

[0076] The developer tank 211 has an opening 211a at an end on the upstream side (front side Y1 in this example) in the second transport direction S2, above the first screw-shaped transport member 212. More specifically, the opening 211a overlaps (intersects with) the rotation axis of the first screw-shaped transport member 212 in a plan view seen from above.

[0077] 9, in the present embodiment, receiving opening 220a is positioned at a position offset from opening 211a so as not to overlap (intersect) with first rotation axis α of first screw-shaped transport member 212. More specifically, receiving opening 220a is offset from opening 211a to one side F1 in the short-side direction F (in this example, the opposite side to photosensitive drum 3 with respect to first rotation axis α) in a plan view seen from above. Receiving opening 220a is offset by a predetermined offset distance d from first rotation axis α of first screw-shaped transport member 212 in the short-side direction F of developer tank 211.

[0078] Furthermore, in this embodiment, opening 211a is provided in developing tank 211 so that end position P1 (in this example, the lower end of inclined surface 221a) on the side where receiving port 220a is offset from opening 211a is located between outer diameter position P2 of the offset side (in this example, one side F1) of first rotating shaft portion 212a in the short direction F of developing tank 211 and outer diameter position P3 of the offset side (in this example, one side F1) of first spiral blade 212b in the short direction F.

[0079] According to the second embodiment, the accuracy of detecting the amount of toner in the developer D can be improved due to the same action as in the first embodiment caused by the inclined surface 221a.

[0080] [Second embodiment-1] The guide portion 220 is provided in the developer tank 211 of the developing device 2. The developing device 2 is detachably attached to the main body 110 of the image forming apparatus 100.

[0081] More specifically, opening 211a is provided on one side E1 (front side Y1 in this example) in the longitudinal direction E of developer tank 211, and guide portion 220 is integrally formed at an end portion of one side E1 (front side Y1 in this example) in the longitudinal direction E of developer tank 211. When developing device 2 is attached to main body 110 of image forming apparatus 100, receiving port 220a of guide portion 220 formed integrally with developer tank 211 communicates with toner supply port 91a in toner storage unit 9 attached to main body 110 of image forming apparatus 100.

[0082] In this configuration, developing device 2 can be attached to or detached from main body 110 of image forming apparatus 100 with guide portion 220 provided in developer tank 211 of developing device 2. This makes it possible to prevent misalignment between guide path 221 and opening 211a in developer tank 211 when developing device 2 is attached to or detached from main body 110 of image forming apparatus 100.

[0083] [Example] FIG. 10 is a graph showing a comparison of the detection value of toner amount detection unit 219 when guide unit 220 according to the present embodiment is used with the detection value of the toner amount detection unit when a conventional guide unit having a guide path along the vertical direction is used.

[0084] As shown in Figure 10, when the guide unit 220 of this embodiment is used, the first elapsed time T1 from when toner T is supplied to the opening 211a until the detection value of the toner amount detection unit (see solid line graph) is stabilized is shorter than the second elapsed time T2 from when toner T is supplied to the opening 211a until the detection value of the toner amount detection unit (see dashed line graph) is stabilized when a conventional guide unit is used.

[0085] That is, when a conventional guide unit is used (see the dashed line graph), second distance L2 (see FIGS. 3B and 8A) corresponding to second elapsed time T2 is the distance from opening 211a to accumulation point ε, and toner amount detection unit 219 cannot detect the toner amount with a stabilized detection value unless it detects the toner amount at accumulation point ε. However, as described above, at accumulation point ε, the bulk density of developer D tends to increase, making it difficult for toner amount detection unit 219 to output the actual detection value, which in turn reduces the accuracy of detecting the toner amount in developer D.

[0086] In contrast, when guiding portion 220 according to the present embodiment is used (see the solid line graph), first distance L1 (see FIGS. 3B and 8A) corresponding to first elapsed time T1 is the distance from intermediate position M between opening 211a and first communicating portion 201a toward opening 211a, and toner amount detection portion 219 does not detect the toner amount at accumulation point ε, thereby effectively preventing a deterioration in the accuracy of detecting the toner amount in developer D due to the bulk density of developer D. Furthermore, because toner T received through receiving opening 220a falls onto inclined surface 221a, toner amount detection portion 219 can detect the toner amount with a stabilized detection value even if first distance L1 is shorter than second distance L2, and therefore, a deterioration in the accuracy of detecting the toner amount in developer D due to the aggregation of toner T can be effectively prevented.

[0087] The present disclosure is not limited to the above-described embodiments, but can be implemented in various other forms. Therefore, the embodiments are merely examples in all respects and should not be interpreted as being limiting. The scope of the present disclosure is defined by the claims and is not bound by the text of the specification. Furthermore, all modifications and variations within the equivalent scope of the claims are within the scope of the present disclosure. [Explanation of symbols]

[0088] 100 Image forming device 110 Main body of image forming device 2. Developing device 201 Room 1 201a 1st communication part 202a 2nd communication part 202 Room 2 211 Developer tank 211a aperture 212 First screw-shaped conveying member 212a First rotating shaft 212b First spiral blade 213 Second screw-shaped conveying member 213a Second rotating shaft 213b Second spiral blade 214 Developing roller (an example of a developer carrier) 214a Developing sleeve 217 Partition Wall 219 Toner amount detection unit 219a Detection surface 220 Information Department 220a Inlet 220b outlet 221 Guideway 221a Slope 221b Opposite section 2. Developing device 3. Photosensitive drum (an example of an image carrier) 9 Toner storage compartment C Carrier D Developer E Longitudinal direction E1 One side E2 other side F Short side direction F1 One side F2 other side L1 1st distance L2 2nd distance M intermediate position P1 end position P2 Outer diameter position P3 Outer diameter position Q1 1st position Q2 2nd position R1 First rotation direction R2 Second rotation direction S1 First conveying direction S2 Second conveying direction T Toner T1 First elapsed time T2 Second elapsed time X Left / right direction Y Front-to-rear direction Z vertical direction e distance α 1st axis of rotation β 2nd axis of rotation γ rotation axis δ rotation axis λ Virtual line ρ Virtual extension line θ Tilt angle

Claims

1. an image forming apparatus including a developing device having a long developing tank that contains a developer including a toner; a first screw-shaped transport member that transports the developer contained in the developing tank in a predetermined first transport direction on one side in the longitudinal direction of the developing tank; a developer carrier that carries the developer contained in the developing tank; and a toner amount detection unit that detects an amount of toner contained in the developer contained in the developing tank, wherein the developing tank has an opening at a position above the first screw-shaped transport member at an end on an upstream side in the first transport direction; a guide section provided with a guide path that guides the toner received through a receiving port to the opening of the developing tank, The image forming apparatus is characterized in that the guide path has an inclined surface that is inclined with respect to the vertical direction and onto which the toner received through the receiving opening falls.

2. 2. The image forming apparatus according to claim 1, wherein the receiving opening is positioned at a position offset from the opening so as not to overlap with the first rotation axis of the first screw-shaped conveying member.

3. 2. The image forming apparatus according to claim 1, wherein the inclined surface is inclined so as to approach an imaginary straight line passing through a first rotation axis of the first screw-shaped transport member and extending in the vertical direction as it extends downward when viewed from the longitudinal direction of the developing tank.

4. 4. The image forming apparatus according to claim 3, wherein the first screw-shaped transport member is driven to rotate from below to above on a side where the receiving opening is offset from the opening.

5. the first screw-shaped conveying member has a first rotating shaft portion and a first helical blade provided on an outer periphery of the first rotating shaft portion, 3. The image forming apparatus according to claim 2, wherein the opening is provided in the developer tank so that an end position of the receiving port on a side offset from the opening is located between an outer diameter position of the offset side of the first rotating shaft portion in the short direction of the developer tank and an outer diameter position of the offset side of the first spiral blade in the short direction.

6. the developing device further includes a second screw-shaped transport member that transports the developer contained in the developer tank in a second transport direction on the other side in the longitudinal direction, the developer tank being provided with a first chamber in which the first screw-shaped transport member is disposed, a second chamber in which the second screw-shaped transport member is disposed, and a first communication portion that communicates the first chamber with the second chamber on the downstream side in the first transport direction, the developer carrier carrying the developer transported by the second screw-shaped transport member, 2. The image forming apparatus according to claim 1, wherein the toner amount detector is provided on the opening side of the first chamber relative to an intermediate position between the opening and the first communicating portion.

7. 7. The image forming apparatus according to claim 6, wherein the first chamber and the second chamber are provided in the developer tank so that the second lowest position of the bottom of the second chamber is located at a position higher than the first lowest position of the bottom of the first chamber, and the first screw-shaped transport member and the second screw-shaped transport member are provided so that the second rotation axis of the second screw-shaped transport member is located at a position higher than the first rotation axis of the first screw-shaped transport member.

8. 2. The image forming apparatus according to claim 1, wherein the guide portion is provided in the developer tank of the developing device.

9. 2. The image forming apparatus according to claim 1, wherein the guide portion is provided in a main body of the image forming apparatus, and the developing device is detachable from the main body of the image forming apparatus.

10. a developing device comprising: a long developing tank containing a developer including a toner; a first screw-shaped transport member that transports the developer contained in the developing tank in a predetermined first transport direction on one side in the longitudinal direction of the developing tank; a developer carrier that carries the developer contained in the developing tank; and a toner amount detection unit that detects an amount of toner contained in the developer contained in the developing tank, wherein the developing tank has an opening at an upstream end in the first transport direction and above the first screw-shaped transport member; a guide section provided with a guide path that guides the toner received through a receiving port to the opening of the developing tank, The developing device is characterized in that the guide path has an inclined surface that is inclined with respect to the vertical direction and onto which the toner received through the receiving opening falls.

Images