JP2012189643A - Developing device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a developing device that prevents backflow of toner from the inside of a developing chamber to a toner replenishing portion and can smoothly replenish toner from the toner replenishing portion to the inside of the developing chamber according to a decrease in toner inside the developing chamber. To do.
A developing chamber has a toner receiving opening, and a toner replenishing portion faces a toner receiving opening and is located above the toner receiving opening, and a toner discharging opening for discharging toner from the toner replenishing portion. Have The toner discharge opening 300 is formed of a pair of sheet members 311 that can be bent toward the developing chamber by the weight of the toner. When the remaining amount of toner in the toner replenishing portion decreases below a certain amount, the toner discharge is performed. A backflow prevention member 310 that closes the opening and prevents the backflow of toner from the developing chamber to the toner supply portion is provided. One end of the pair of sheet members 311 constitutes a fixed end 313, and the other end of the pair of sheet members 311 constitutes a free end 314 that can be bent toward the developing chamber by the weight of the toner. ing.
[Selection] Figure 8

Description

  The present invention relates to a developing device for supplying toner to an electrostatic latent image formed on the surface of an image carrier and developing the electrostatic latent image into a toner image, and an image forming apparatus including the developing device.

  A developing device in an image forming apparatus such as an electrophotographic printer, a copier, a facsimile, and the like includes a toner carrier that carries toner, a housing that has a developing chamber that contains the toner carrier, and replenishes toner inside the developing chamber. A toner replenishing unit that is disposed inside the developing chamber, and a toner conveying unit that conveys the toner inside the developing chamber to a toner carrier. The developing chamber has a toner receiving opening above it, and the toner replenishing section has a toner discharge opening at a position facing the toner receiving opening and above the toner receiving opening. There are many.

  In the developing device of the above-described form, the toner accommodated in the toner replenishing portion is replenished into the developing chamber through the toner discharge opening and the toner receiving opening. In this case, when the remaining amount of toner in the toner replenishing portion decreases below a certain amount, the toner replenishing pressure (pressing force) from the toner replenishing portion into the developing chamber decreases. Therefore, there is a possibility that the toner flows backward from the toner receiving area inside the developing chamber to the toner replenishing portion through the toner receiving opening and the toner discharging opening. As described above, when the toner in the developing chamber flows backward to the toner replenishing portion, the fluctuation of the remaining amount of toner in the toner replenishing portion increases, and as a result, the prediction accuracy of the remaining amount of toner in the toner replenishing portion decreases. It is easy to cause inconvenience that the user replaces the toner cartridge (toner supply unit) while a large amount of unused toner remains.

  In order to prevent the backflow of the toner from the developing chamber to the toner replenishing portion as described above, a shutter member that opens and closes the toner discharge opening by swinging up and down with one side of the discharge opening as a fulcrum is disposed in the toner discharge opening. A developing device having a configuration has been proposed (see, for example, Patent Documents 1 and 2).

JP-A-8-152787 JP 2004-205561 A

  However, in the developing devices described in Patent Documents 1 and 2, since the inclination angle of the shutter member that opens the toner discharge opening is very gentle, when toner is supplied from the toner supply unit to the inside of the developing chamber. Only a small opening area of the shutter can be secured. For this reason, there is a problem that toner cannot be replenished smoothly and it takes a long time to replenish the toner into the developing chamber.

The present invention replenishes toner smoothly and quickly from the toner replenishing portion to the inside of the developing chamber in accordance with the decrease in toner inside the developing chamber while preventing the backflow of toner from the inside of the developing chamber to the toner replenishing portion. It is an object of the present invention to provide a developing device that can do this.
Another object of the present invention is to provide an image forming apparatus including the developing device.

  The present invention provides a toner carrier for carrying toner, a housing having a developing chamber for containing the toner carrier, a toner replenishing portion for replenishing toner inside the developing chamber, and an inside of the developing chamber. And a toner conveying unit that conveys toner inside the developing chamber to the toner carrier, wherein the developing chamber has a toner receiving opening above it for receiving toner therein. The toner replenishing portion has a toner discharge opening for discharging the toner from the toner replenishment portion at a position opposite to the toner receiving opening and above the toner receiving opening; And a backflow prevention member formed of a sheet member capable of being bent toward the developing chamber by its own weight, wherein the remaining amount of toner in the toner replenishing portion is reduced to a predetermined amount or less. A backflow prevention member that closes the toner discharge opening to prevent the backflow of toner from the developing chamber to the toner replenishing portion is provided, and the backflow prevention member is formed from a pair of the sheet members, One end of each of the pair of sheet members constitutes a fixed end that is fixed to an opposite side of the toner discharge opening, and the other end of each of the pair of sheet members is in the developing chamber due to its own weight. The present invention relates to a developing device that forms a free end that can be bent sideways.

  The toner replenishing portion preferably constitutes a part of a toner cartridge that is detachably attached to the housing.

  Preferably, the toner discharge opening is provided with an entry restricting member that restricts the backflow preventing member from entering the inside of the toner replenishing portion.

  According to the present invention, an electrostatic latent image is formed on the surface of the developing device and a toner image is formed on the electrostatic latent image by receiving toner from the toner carrier of the developing device. Alternatively, a plurality of image carriers, a transfer unit that directly or indirectly transfers a toner image formed on the image carrier to a sheet-like transfer material, and the transferred toner image to the sheet-like transfer target The present invention relates to an image forming apparatus including a fixing unit that fixes to a material.

According to the present invention, toner is smoothly and quickly transferred from the toner replenishing portion to the inside of the developing chamber in accordance with a decrease in the toner inside the developing chamber while preventing the backflow of toner from the inside of the developing chamber to the toner replenishing portion. Can be provided.
In addition, according to the present invention, an image forming apparatus including the developing device can be provided.

It is a front view for demonstrating arrangement | positioning of each component in the printer 1 of 1st Embodiment of this invention. It is a disassembled perspective view which shows the structure concerning the developing device 16 shown in FIG. FIG. 3 is an exploded sectional view of a configuration related to the developing device 16 shown in FIG. 2. FIG. 3 is a cross-sectional view of a configuration related to the developing device 16 shown in FIG. 2. FIG. 3 is a plan view of the developing device 16 shown in FIG. 2. FIG. 2 is a perspective view of the toner cartridge 5 shown in FIG. 1 viewed from the bottom side. FIG. 3 is a plan view showing the toner cartridge 5 shown in FIG. 2 with a lid 202 removed. 4 is an enlarged plan view of the vicinity of a toner discharge opening 300 in the developing device 16. FIG. 4 is an enlarged cross-sectional view of a state in which a toner discharge opening 300 in the developing device 16 is closed by a backflow prevention member 310. FIG. FIG. 4 is an enlarged cross-sectional view of a state where a toner discharge opening 300 in the developing device 16 is opened. 6 is an enlarged cross-sectional view illustrating a state where toner TN is supplied from a toner discharge opening 300 to the developing chamber 160 in the developing device 16. FIG. FIG. 6 is an enlarged cross-sectional view illustrating a state where the amount of toner TN replenished from the toner discharge opening 300 in the developing device 16 to the developing chamber 160 is increased. 4 is an enlarged cross-sectional view illustrating a state in which the back flow of the toner TN from the developing chamber 160 to the toner cartridge 5 side in the developing device 16 is prevented. FIG. 6 is a graph showing experimental results in Examples, and is a graph showing the relationship between the total toner consumption and the remaining amount of toner in the toner cartridge. 6 is a graph showing experimental results in Examples, and is a graph showing the relationship between the total toner consumption and the remaining amount of toner in the toner cartridge. 6 is a graph showing experimental results in Examples, and is a graph showing the relationship between the total toner consumption and the remaining amount of toner in the developing chamber 160. FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
With reference to FIG. 1, the overall structure of a printer 1 as an image forming apparatus in the first embodiment of the present invention will be described. FIG. 1 is a front view for explaining the arrangement of components in the printer 1 according to the first embodiment of the present invention.

As shown in FIG. 1, a printer 1 as an image forming apparatus includes an apparatus main body M and an image forming unit GK that forms a predetermined toner image on a sheet T as a sheet-like transfer material based on predetermined image information. And a paper supply / discharge unit KH that supplies the paper T to the image forming unit GK and discharges the paper T on which the toner image is formed.
The outer shape of the apparatus main body M is configured by a case body BD as a casing.

  As shown in FIG. 1, the image forming unit GK includes a photosensitive drum 2 as an image carrier (photosensitive member), a charging unit 10, a laser scanner unit 4 as an exposure unit, and a developing device 16 (toner supply unit). 6), a toner cartridge 5, a drum cleaning unit 11, a static eliminator 12, a transfer roller 8, and a fixing unit 9.

  As shown in FIG. 1, the paper feed / discharge unit KH includes a paper feed cassette 52, a manual paper feed unit 64, a transport path L for paper T, a registration roller pair 80, and a paper discharge unit 50.

Hereinafter, each configuration of the image forming unit GK and the paper supply / discharge unit KH will be described in detail.
First, the image forming unit GK will be described.
In the image forming unit GK, in order from the upstream side to the downstream side along the surface of the photosensitive drum 2, charging by the charging unit 10, exposure by the laser scanner unit 4, development by the developing device 16, transfer by the transfer roller 8. Then, static elimination by the static eliminator 12 and cleaning by the drum cleaning unit 11 are performed.

  The photosensitive drum 2 is made of a cylindrical member and functions as a photosensitive member or an image carrier. The photosensitive drum 2 is disposed so as to be rotatable in the direction of an arrow about an axis extending in a direction orthogonal to the conveyance direction of the paper T in the conveyance path L. An electrostatic latent image can be formed on the surface of the photosensitive drum 2.

  The charging unit 10 is disposed to face the surface of the photosensitive drum 2. The charging unit 10 uniformly charges the surface of the photosensitive drum 2 to be negative (minus polarity) or positive (plus polarity).

  The laser scanner unit 4 functions as an exposure unit, and is disposed away from the surface of the photosensitive drum 2. The laser scanner unit 4 includes a laser light source (not shown), a polygon mirror, a polygon mirror driving motor, and the like.

  The laser scanner unit 4 scans and exposes the surface of the photosensitive drum 2 based on image information input from an external device such as a PC (personal computer). By scanning exposure with the laser scanner unit 4, the charge on the exposed portion of the surface of the photosensitive drum 2 is removed. As a result, an electrostatic latent image is formed on the surface of the photosensitive drum 2.

  The developing device 16 is provided corresponding to the photosensitive drum 2 and is disposed to face the surface of the photosensitive drum 2. The developing device 16 attaches a single color (usually black) toner to the electrostatic latent image formed on the photoconductive drum 2 to form a single color toner image on the surface of the photoconductive drum 2. The developing device 16 includes a developing roller 17 as a toner carrying member disposed opposite to the surface of the photosensitive drum 2, a first toner stirring / transporting spiral blade 19 and a second toner stirring / transporting spiral blade. 18 and a toner replenishing section 20 and the like.

  The toner cartridge 5 stores toner supplied to the developing chamber 160 in the developing device 16. The toner cartridge 5 and the toner replenishing unit 6 are integrally configured.

The toner replenishing unit 6 supplies the toner stored in the toner cartridge 5 to the developing chamber 160 in the developing device 16. The toner replenishing unit 6 and the developing chamber 160 in the developing device 16 are connected by a toner supply path described later.
Details of the configuration related to the developing device 16 and the toner cartridge 5 will be described later.

  The transfer roller 8 transfers the toner image developed on the surface of the photosensitive drum 2 to the paper T. A transfer bias for transferring the toner image formed on the photosensitive drum 2 to the paper T is applied to the transfer roller 8 by a transfer bias applying unit (not shown). The transfer roller 8 is configured to be rotatable while being in contact with the photosensitive drum 2.

  A sheet T conveyed through the conveyance path L is sandwiched between the photosensitive drum 2 and the transfer roller 8. The sandwiched paper T is pressed against the surface of the photosensitive drum 2. A transfer nip N is formed between the photosensitive drum 2 and the transfer roller 8. In the transfer nip N, the toner image developed on the photosensitive drum 2 is transferred onto the paper T.

  The static eliminator 12 is disposed to face the surface of the photosensitive drum 2. The static eliminator 12 irradiates the surface of the photosensitive drum 2 with light, thereby neutralizing the surface of the photosensitive drum 2 after the transfer is performed (removing the electric charge).

  The drum cleaning unit 11 is disposed to face the surface of the photosensitive drum 2. The drum cleaning unit 11 removes toner and deposits remaining on the surface of the photosensitive drum 2, and transports the removed toner and the like to a predetermined recovery mechanism (not shown) for recovery.

  The fixing unit 9 melts and presses the toner constituting the toner image transferred to the paper T and fixes the toner on the paper T. The fixing unit 9 includes a heating rotator 9a heated by a heater and a pressure rotator 9b pressed against the heating rotator 9a. The heating rotator 9a and the pressure rotator 9b sandwich and pressurize the paper T on which the toner image has been transferred, and convey the paper T. By transporting the paper T while being sandwiched between the heating rotator 9a and the pressure rotator 9b, the toner transferred onto the paper T is melted and pressurized, and is fixed to the paper T.

Next, the paper supply / discharge unit KH will be described.
As shown in FIG. 1, in the lower part of the apparatus main body M, a single paper feed cassette 52 that stores paper T is disposed. The paper feed cassette 52 is configured to be drawable in the horizontal direction from the right side (the right side in FIG. 1) of the apparatus main body M. In the paper feed cassette 52, a placement plate 60 on which the paper T is placed is disposed. In the paper feed cassette 52, the paper T is stored in a state of being stacked on the placement plate 60. The paper T placed on the placement plate 60 is sent out to the transport path L by the cassette paper feed unit 51 arranged at the paper feed side end of the paper feed cassette 52 (the right end in FIG. 1). The cassette paper feed unit 51 includes a forward feed roller 61 for taking out the paper T on the placement plate 60 and a paper feed roller pair 63 for feeding the paper T one by one to the transport path L. Is provided.

  On the right side (right side in FIG. 1) of the apparatus main body M, a manual paper feed unit 64 is provided. The manual paper feed unit 64 is provided mainly for supplying the apparatus main body M with a paper T of a size and type different from the paper T set in the paper feed cassette 52. The manual paper feed unit 64 includes a manual feed tray 65 that forms a part of the front surface of the apparatus main body M in the closed state, and a paper feed roller 66. The lower end of the manual feed tray 65 is attached to the vicinity of the paper feed roller 66 so as to be rotatable (openable and closable). The paper T is placed on the open manual feed tray 65. The paper feed roller 66 feeds the paper T placed on the open manual feed tray 65 to the manual feed path La.

  A paper discharge unit 50 is provided on the upper side of the apparatus main body M. The paper discharge unit 50 discharges the paper T to the outside of the apparatus main body M by the third roller pair 53. Details of the paper discharge unit 50 will be described later.

  The conveyance path L for conveying the paper T is a first conveyance path L1 from the cassette paper feeding unit 51 to the transfer nip N, a second conveyance path L2 from the transfer nip N to the fixing unit 9, and a discharge from the fixing unit 9. A third conveyance path L3 to the section 50, a manual conveyance path La that joins the paper supplied from the manual sheet feeding unit 64 to the first conveyance path L1, and a third conveyance path L3 from the downstream side to the upstream side. And a return transport path Lb that reverses the front and back and returns the sheet to the first transport path L1.

Moreover, the 1st junction part P1 and the 2nd junction part P2 are provided in the middle of the 1st conveyance path L1. A first branch portion Q1 is provided in the middle of the third transport path L3.
The first joining part P1 is a joining part where the manual feed path La joins the first transport path L1. The second junction P2 is a junction where the return conveyance path Lb merges with the first conveyance path L1.
The first branch portion Q1 is a branch portion where the return transport path Lb branches from the third transport path L3, and includes a first roller pair 54a and a second roller pair 54b. One roller of the first roller pair 54a and one roller of the second roller pair 54b are combined.

  A sensor (not shown) for detecting the paper T and a skew of the paper T (oblique feeding) are in the middle of the first conveyance path L1 (specifically, between the second joining portion P2 and the transfer roller 8). ) A registration roller pair 80 is arranged for matching the timing of correction and toner image formation in the image forming unit GK. The sensor is disposed immediately before the registration roller pair 80 in the transport direction of the paper T (upstream in the transport direction). The registration roller pair 80 conveys the paper T by performing the above-described correction and timing adjustment based on detection signal information from the sensor.

The return conveyance path Lb is a conveyance path that is provided so that the opposite surface (unprinted surface) to the surface that has already been printed faces the photosensitive drum 2 when performing duplex printing on the paper T.
According to the return conveyance path Lb, the sheet T conveyed from the first branching section Q1 to the paper discharge section 50 side by the first roller pair 54a is reversed and returned to the first conveyance path L1 by the second roller pair 54b. , And can be conveyed to the upstream side of the registration roller pair 80 disposed on the upstream side of the transfer roller 8. A predetermined toner image is transferred onto the unprinted surface at the transfer nip N on the paper T that is reversed upside down by the return conveyance path Lb.

  A paper discharge unit 50 is formed at the end of the third transport path L3. The paper discharge unit 50 is disposed on the upper side of the apparatus main body M. The paper discharge unit 50 opens toward the right side of the apparatus main body M (the right side in FIG. 1, the manual paper feed unit 64 side). The paper discharge unit 50 discharges the paper T conveyed on the third conveyance path L3 to the outside of the apparatus main body M by the third roller pair 53.

On the opening side of the paper discharge unit 50, a paper discharge stacking unit M1 is formed. The paper discharge stacking unit M1 is formed on the upper surface (outer surface) of the apparatus main body M. The paper discharge stacking unit M1 is a part formed by the upper surface of the apparatus main body M being depressed downward. The bottom surface of the paper discharge stacking unit M1 constitutes a part of the top surface of the apparatus main body M. In the paper discharge stacking unit M1, sheets T formed with a predetermined toner image and discharged from the paper discharge unit 50 are stacked and stacked.
A paper detection sensor is disposed at a predetermined position on each conveyance path.

  To briefly summarize the configuration of the printer 1 as the image forming apparatus described above, the printer 1 includes a photosensitive drum 2 as an image carrier on which an electrostatic latent image is formed, and a photosensitive drum 2. A charging unit 10 that charges the surface; and a developing device 16 that forms a toner image on the surface of the photosensitive drum 2 by attaching toner to the electrostatic latent image formed on the photosensitive drum 2 charged by the charging unit 10. A transfer roller 8 serving as a transfer unit for directly or indirectly transferring a toner image formed on the photosensitive drum 2 to a sheet T as a sheet-like transfer material; and a toner image transferred onto the sheet T And a fixing unit 9 that fixes the toner to be fixed to the paper T.

  Hereinafter, the configuration related to the developing device 16 and the toner cartridge 5 in the printer 1 of the present embodiment will be described in detail with reference to FIGS. FIG. 2 is an exploded perspective view showing the configuration of the developing device 16 shown in FIG. FIG. 3 is an exploded cross-sectional view of the configuration related to the developing device 16 shown in FIG. FIG. 4 is a cross-sectional view of a configuration related to the developing device 16 shown in FIG. FIG. 5 is a plan view of the developing device 16 shown in FIG. FIG. 6 is a perspective view of the toner cartridge 5 shown in FIG. 1 viewed from the bottom side. FIG. 7 is a plan view showing the toner cartridge 5 shown in FIG. 2 with the lid 202 removed.

  As shown in FIGS. 2 to 4, the developing device 16 of this embodiment includes a developing roller 17, a housing 162 having a developing chamber 160, a toner replenishing unit 20 that replenishes toner in the developing chamber 160, and a toner A first toner agitating and conveying spiral blade 19 and a second toner agitating and conveying spiral blade 18 serving as a conveying unit are provided.

  The housing 162 includes a housing main body 163 and an upper surface wall member 164 attached to the housing main body 163. The developing chamber 160 accommodates the developing roller 17. A developing chamber 160 that opens upward and toward the photosensitive drum 2 is formed on the developing roller 17 side (the left side in FIGS. 3 and 4) of the housing body 163. The developing chamber 160 has a toner receiving opening 220 for receiving toner therein.

  As shown in FIGS. 2 to 4, the housing body 163 includes a bottom wall 165, side walls 166, and a connecting wall 167. The connecting wall 167 extends between the upper edges of the side walls 166. The bottom wall 165 of the housing body 163 has three semicircular arc-shaped portions 165a, 165b and 165c arranged in parallel. An upright wall 168 extending substantially vertically upward is provided between the arc-shaped portion 165a and the arc-shaped portion 165b. On both sides of the upright wall 168, straight paths 169a and 169b are formed. The straight paths 169a and 169b communicate with each other at both ends of the paths. An endless toner circulation path is formed by the linear paths 169a and 169b.

  As shown in FIGS. 2 to 4, the toner replenishing portion 20 constitutes a part of the toner cartridge 5 that is detachably attached to the housing 162. The toner replenishing unit 20 replenishes toner in the developing chamber 160.

  As shown in FIGS. 2 to 4, the first toner agitating / conveying spiral blade 19 and the second toner agitating / conveying spiral blade 18 are disposed inside the developing chamber 160, and the toner inside the developing chamber 160 Is conveyed to the developing roller 17. The first toner stirring and conveying spiral blade 19 is disposed in one linear path 169a. The second toner stirring and conveying spiral blade 18 is disposed in the other linear path 169b. The first toner stirring and conveying spiral blade 19 and the second toner stirring and conveying spiral blade 18 are rotatably supported between both side walls 166 of the housing body 163. The first toner stirring / conveying spiral blade 19 and the second toner stirring / conveying spiral blade 18 are a passive gear 172 that meshes with a drive gear 171 connected to the electric motor 170, and a passive gear (not shown) that meshes with the passive gear 172. 3), each is rotated in the direction of the arrow shown in FIG.

  As shown in FIG. 5, the spiral direction of the first toner stirring and conveying spiral blade 19 and the spiral direction of the second toner stirring and conveying spiral blade 18 are set in reverse. By rotating the first toner stirring and conveying spiral blade 19 in the direction of arrow A, the toner TN is conveyed in the direction of arrow A1 through the linear path 169a. By rotating the second toner stirring and conveying spiral blade 18 in the direction of arrow B, the toner TN is conveyed in the direction of arrow B1 through the linear path 169b.

  As shown in FIG. 5, the spiral blade 18 a has the outer diameter of the spiral blade 18 a in the other part of the specific region C in the substantially central portion in the transport direction B <b> 1 of the second toner stirring and transporting spiral blade 18. It is comprised so that it may become small locally compared with the outer diameter of. Thereby, the conveyance capability in the specific area C is locally reduced.

  The specific area C in which the conveyance capability is locally reduced is located at the downstream end of the toner receiving area. This toner receiving area is an area where the toner TN is introduced into the developing chamber 160 through a toner receiving opening 220 described later. Since the transport capability in the specific area C located downstream of the toner receiving area is locally reduced, toner retention (stagnation) is generated in the toner receiving area in the developing chamber 160. Due to the retention of the toner, the introduction of the toner from the toner replenishing unit 20 into the developing chamber 160 can be automatically controlled. Accordingly, the toner can be appropriately supplied into the developing chamber 160 without controlling the driving of the first toner stirring and conveying spiral blade 19 and the second toner stirring and conveying spiral blade 18.

As shown in FIGS. 2 to 4, the upper wall member 164 is attached to the housing body 163. The upper surface wall member 164 has an upper surface wall 180 that covers the upper surface of the developing chamber 160. The upper surface wall 180 is formed with an elongated immersion area 181 extending in the width direction (direction perpendicular to the paper surface in FIGS. 3 and 4). A toner receiving opening 220 is formed in the immersion area 181.
The top wall member 164 has an upstanding wall 182 that extends along the immersion area 181. A pair of support bars 183 that protrude substantially horizontally are provided on the upright wall 182 at intervals in the width direction (direction perpendicular to the paper surface in FIGS. 3 and 4). In FIGS. 3 and 4, only one support bar 183 is shown.

  A developing chamber shutter 184 is attached to the upper surface wall member 164. The developing chamber shutter 184 has a flat shutter wall 185. A pair of protrusions 186 are formed on the upper surface of the shutter wall 185. An inclined surface 187 is formed at the tip of the protrusion 186. The protrusion 186 includes an extending portion extending rearward (leftward in FIGS. 3 and 4) from the inclined surface 187. As shown in FIG. 2, the shutter wall 185 has a pair of protrusions 188 that protrude forward from both ends thereof.

The developing chamber shutter 184 is mounted so as to be movable along the upper surface of the upper surface wall 180 of the upper surface wall member 164. The developing chamber shutter 184 can be switched between a closed position shown in FIG. 3 and an open position shown in FIG.
A compression coil spring 189 is interposed between the pair of support rods 183 on the upper surface wall member 164 and the extending portions of the pair of protrusions 186 on the developing chamber shutter 184. The compression coil spring 189 elastically biases the developing chamber shutter 184 to the closed position shown in FIG.

  With the above configuration, in the present embodiment, the elastic biasing force of the compression coil spring 189 in the state where the upper surface wall member 164 is mounted on the housing body 163 and the developing chamber shutter 184 is mounted on the upper wall member 164. Thus, the developing chamber shutter 184 is disposed at the closed position shown in FIG. As a result, the tips of the pair of protrusions 188 of the developing chamber shutter 184 abut against the upright wall 190 (FIGS. 3 and 5) of the housing body 163, and the developing chamber shutter 184 moves beyond the closed position in FIG. Is blocked. When the developing chamber shutter 184 is positioned at the closed position, the shutter wall 185 covers (closes) the toner receiving opening 220 in the upper wall member 164 as shown in FIG.

  When the toner cartridge 5 is attached to the housing main body 163, the toner cartridge 5 acts on the inclined surface 187 of the developing chamber shutter 184, and the developing chamber shutter 184 is elastically attached to the compression coil spring 189, as will be described later. It is moved to the open position shown in FIG. 4 against the force. When the developing chamber shutter 184 is moved to the open position, the shutter wall 185 is retracted from above the toner receiving opening 220, and the toner receiving opening 220 is exposed (opened).

As shown in FIG. 2, the upper wall member 164 is formed with an upright wall 191 that protrudes upward from one edge of the upper wall 180 in the width direction. A guide groove 192 extending downward from the upper end is formed in the upright wall 191.
The upper surface wall 180 has a storage wall portion 193 extending in the width direction. Locking means 194 is stored in the storage wall 193. As shown in FIGS. 2 to 4, the locking means 194 includes a main portion 195 that is elongated in the width direction (a direction perpendicular to the paper surface in FIGS. 2 and 3), and an operation arm 196 that protrudes upward from the main portion 195. Have.

Next, the toner cartridge 5 will be described.
As shown in FIGS. 2 to 4 and 6, the toner cartridge 5 includes a cartridge case 200. The cartridge case 200 includes a box-shaped case main body 201 having an upper surface opened and a lid body 202 fixed to the opening on the upper surface of the case main body 201. The case body 201 has two arcuate portions 203a and 203b on the bottom wall. The radius of curvature of one arcuate portion 203a is larger than the radius of curvature of the other arcuate portion 203b.

  As shown in FIG. 6, the arcuate portion 203b having a small curvature radius is formed with a protruding region 204 that protrudes downward. The protruding region 204 is also arc-shaped, and is concentric with the non-projecting region (non-projecting region) in the arc-shaped portion 203b. The length in the width direction and the radius of curvature of the protruding area 204 correspond to the axial length and the radius of curvature of the immersion area 181 formed in the upper surface wall 180 of the upper surface wall member 164. The protruding area 204 constitutes the toner supply unit 20. A toner discharge opening 300 is formed in the bottom wall portion of the protruding area 204.

  The toner discharge opening 300 is an opening for discharging the toner from the toner replenishing unit 20 at a position facing the toner receiving opening 220 and above the toner receiving opening 220. The toner discharge opening 300 is formed in a rectangular shape having a long side along the axial direction of the arc-shaped protruding region 204 and a short side along the circumferential direction.

  As shown in FIG. 4, when the toner cartridge 5 is mounted on the housing 162 in a predetermined manner, the protruding area 204 of the case body 201 is placed in the immersion area 181 formed on the upper surface wall 180 of the upper surface wall member 164. Is done. Accordingly, the toner discharge opening 300 is positioned above the toner receiving opening 220 so as to face the toner receiving opening 220. The width and length of the toner discharge opening 300 are formed substantially the same as or slightly smaller than the width and length of the toner receiving opening 220.

  As shown in FIGS. 6 and 7, the case main body 201 has both side walls 206. On one side wall 206, an opening 207 for filling the toner in the cartridge case 200 is formed. A closing member 208 that closes the opening 207 after toner filling is fixed to the opening 207.

  As shown in FIGS. 3, 4 and 7, between the side walls 206 of the case body 201, the first toner conveying device 209 extending along the arc-shaped portion 203a and the arc-shaped portion 203b extend. A second toner conveying device 210. The first toner transport device 209 includes a rotation support shaft 211 that is rotatably mounted between both side walls 206, and a plurality of rectangular transport pieces 212 that are fixed to the rotation support shaft 211. One end of the rotation support shaft 211 passes through one side wall 206 and protrudes outward from the case body 201. An input gear 215 is fixed to the protruding shaft end of the rotation support shaft 211.

  The second toner conveying device 210 is composed of a rotating spiral blade member having a rotation support shaft 213 and a spiral blade 214. One end of the rotation support shaft 213 protrudes through one side wall 206. An input gear 216 is fixed to the protruding shaft end of the rotation support shaft 213. The input gear 216 is meshed with the input gear 215 of the rotation support shaft 211 in the first toner conveying device 209.

  With the above configuration, when the toner cartridge 5 is mounted on the housing 162 in a predetermined manner, the input gear 215 is engaged with the drive gear 171 mounted on the housing body 163 and connected to the electric motor 170. In this state, when the electric motor 170 is started, the first toner agitating / conveying spiral blade 19 and the second toner agitating / conveying spiral blade 18 disposed in the developing chamber 160 are driven and rotated, and the toner The first toner transport device 209 and the second toner transport device 210 in the cartridge 5 are driven and rotated in the direction of the arrow. As a result, the toner TN present on the arcuate portion 203a is conveyed onto the arcuate portion 203b by the first toner conveying device 209. Further, the toner TN on the arcuate portion 203b is transported toward the toner discharge opening 300 by the second toner transport device 210.

  As shown in FIGS. 3, 4 and 7, the cartridge case 200 has a cartridge shutter 230 disposed in the protruding region 204 of the arcuate portion 203b. The cartridge shutter 230 has an arcuate shutter member 231 over an angle range of approximately 200 degrees. A toner passage opening 232 is formed in the shutter member 231. The toner passage opening 232 of the shutter member 231 is formed in substantially the same size and shape as the toner discharge opening 300 in the case body 201.

As shown in FIG. 6, a pair of locked pieces 233 are provided on the rear wall portion of the case main body 201 in the toner cartridge 5 at intervals in the width direction. The locked piece 233 has a hook shape and includes an inclined surface 234 and a horizontal surface 235.
When the toner cartridge 5 is mounted in the housing 162 of the developing device 16, the inclined surface 234 of the pair of locked pieces 233 acts on the inclined surface (not shown) of the locking means 194 of the housing 162, thereby 194 is moved to the unlocked position against the elastic biasing force. When the toner cartridge 5 is mounted at a predetermined position, the inclined surface 234 of the locked piece 233 passes through the inclined surface of the locking means 194, and the locking means 194 returns to the locked position by an elastic biasing force. . As a result, the toner cartridge 5 is locked and mounted at a predetermined position of the housing 162.

  Next, a characteristic configuration of the developing device 16 in the printer 1 of the present embodiment will be described in detail with reference to FIGS. 8 to 10. FIG. 8 is an enlarged plan view near the toner discharge opening 300 in the developing device 16. FIG. 9 is an enlarged cross-sectional view of the developing device 16 in a state where the toner discharge opening 300 is closed by the backflow prevention member 310. FIG. 10 is an enlarged cross-sectional view of the developing device 16 with the toner discharge opening 300 opened.

  As shown in FIGS. 8 to 10, a backflow preventing member 310 is provided in the toner discharge opening 300 of the developing device 16. The backflow prevention member 310 is formed of an elastic sheet member that can be bent downward, that is, toward the developing chamber 160 by the weight of the toner TN. The backflow prevention member 310 can close the toner discharge opening 300 when the remaining amount of the toner TN in the toner replenishing unit 20 is reduced to a certain amount or less, whereby the toner from the developing chamber 160 to the toner replenishing unit 20 can be closed. It serves to prevent TN backflow.

The backflow prevention member 310 is formed of a pair of sheet members 311 and 311 divided in the long side direction of the toner discharge opening 300.
The pair of sheet members 311 and 311 are formed in the same shape. The pair of sheet members 311, 311 has a length that is approximately half the length of the toner discharge opening 300 in the long side direction and a width that is the same as or slightly longer than the short side direction of the toner discharge opening 300. One end portions in the length direction of the pair of sheet members 311 and 311 are respectively attached to the pair of plate members 312 and 312 in a wound state. The pair of plate members 312 and 312 are disposed along the opposing short sides of the toner discharge opening 300. One end of the pair of sheet members 311 and 311 in the length direction constitutes fixed ends 313 and 313. The other ends of the pair of sheet members 311 and 311 constitute free ends 314 and 314 that can be bent toward the developing chamber 160 by the weight of the toner TN, respectively.

  As shown in FIGS. 8 to 10, the toner discharge opening 300 is provided with entry restricting members 320 and 320 that restrict the backflow preventing member 310 from entering the inside of the toner replenishing unit 20. Specifically, the pair of plate-like entry restriction members 320, 320 are extended from the center portion in the width direction of the pair of plate members 312, 312 toward the center portion in the longitudinal direction of the toner discharge opening 300. . As shown in FIG. 9, the pair of entry restricting members 320 and 320 are paired when the pair of sheet members 311 and 311 are pushed by the toner TN on the developing chamber 160 side and bent toward the toner discharge opening 300. It contacts the upper surface of the sheet members 311 and 311. Accordingly, the pair of entry restricting members 320 and 320 restrict the free ends 314 and 314 of the pair of sheet members 311 and 311 from entering the inside of the toner supply unit 20.

  It should be noted that the pair of entry restricting members 320, 320 are strong and have a backflow prevention function so as not to obstruct the flow of the toner TN when the toner TN is replenished from the toner replenishing unit 20 side to the developing chamber 160. The width is as narrow as possible and the extension length is as short as possible.

Next, the operation of the printer 1 of the first embodiment will be briefly described with reference to FIG.
First, a case where single-sided printing is performed on the paper T stored in the paper feed cassette 52 will be described.
The paper T accommodated in the paper feed cassette 52 is sent out to the first transport path L1 by the forward feed roller 61 and the paper feed roller pair 63, and then the registration rollers via the first junction P1 and the first transport path L1. Transported to pair 80.
In the registration roller pair 80, skew correction of the paper T and timing adjustment with the toner image are performed.

The paper T discharged from the registration roller pair 80 is introduced into the transfer nip N between the photosensitive drum 2 and the transfer roller 8 via the first conveyance path L1. A toner image is transferred onto the paper T between the photosensitive drum 2 and the transfer roller 8.
Thereafter, the paper T is discharged from between the photosensitive drum 2 and the transfer roller 8 and is fixed to the fixing nip between the heating rotator 9a and the pressure rotator 9b in the fixing unit 9 via the second conveyance path L2. To be introduced. Then, the toner TN is melted in the fixing nip, and the toner TN is fixed on the paper T.

Next, the paper T is conveyed to the paper discharge unit 50 through the third conveyance path L3 by the first roller pair 54a, and is discharged from the paper discharge unit 50 to the paper discharge stacking unit M1 by the third roller pair 53.
In this way, single-sided printing of the paper T stored in the paper feed cassette 52 is completed.

  When single-sided printing is performed on the paper T placed on the manual feed tray 65, the paper T placed on the manual feed tray 65 is sent out to the manual feed path La by the paper feed roller 66, and then the first joining portion. It is conveyed to the registration roller pair 80 via P1 and the first conveyance path L1. Subsequent operations are the same as the one-side printing operation of the paper T accommodated in the paper feed cassette 52 described above, and a description thereof will be omitted.

Next, the operation of the printer 1 when performing duplex printing will be described.
In the case of single-sided printing, as described above, the paper T on which single-sided printing has been performed is discharged from the paper discharge unit 50 to the paper discharge stacking unit M1, and the printing operation is completed.
On the other hand, when performing double-sided printing, the paper T that has been printed on one side is reversed from the front and back of the single-sided printing via the return conveyance path Lb, and is conveyed again to the registration roller pair 80. Double-sided printing is performed on the paper T.

  More specifically, the operation is the same as the above-described single-sided printing operation until the paper T on which single-sided printing has been performed is discharged from the paper discharge unit 50 by the third roller pair 53. Thus, in the case of double-sided printing, the rotation of the third roller pair 53 is stopped and rotated in the opposite direction while the paper T on which single-sided printing has been held by the third roller pair 53. Thus, when the third roller pair 53 is rotated in the reverse direction, the paper T held by the third roller pair 53 moves in the reverse direction (from the paper discharge unit 50 to the first branching unit Q1) along the third conveyance path L3. Transported in the direction of heading).

  As described above, when the paper T is transported in the reverse direction along the third transport path L3, it is introduced into the second roller pair 54b. Then, the paper T joins the first transport path L1 via the return transport path Lb and the second joining portion P2. Here, the paper T is turned upside down from the one-side printing.

  Further, the paper T is corrected or adjusted by the registration roller pair 80 and is introduced between the photosensitive drum 2 and the transfer roller 8 through the first conveyance path L1. Since the non-printing surface of the paper T passes through the return conveyance path Lb, the non-printing surface faces the photosensitive drum 2, so that the toner image is transferred to the non-printing surface, and as a result, duplex printing is performed.

Next, in the developing device 16 of this embodiment, an operation for supplying the toner TN into the developing chamber 160 from the toner supply unit 20 that also constitutes a part of the toner cartridge 5 will be described.
When a sufficient amount of toner TN is accommodated in the toner cartridge 5 and the remaining amount of toner TN in the toner replenishing unit 20 is maintained at a constant amount, the toner TN in the toner replenishing unit 20 causes a back flow due to its own weight. As shown in FIG. 11, the pair of sheet members 311 and 311 forming the prevention member 310 is bent toward the developing chamber 160 to open the toner discharge opening 300.

  Here, since the pair of sheet members 311 and 311 are formed from flexible elastic sheet members, the pair of sheet members 311 and 311 are free ends when receiving a downward pushing force F due to their own weight. 314 and 314 side is greatly bent downward and deformed. Accordingly, it is possible to secure a large opening area of the toner discharge opening 300, and it is possible to smoothly and efficiently replenish toner from the toner replenishing unit 20 to the developing chamber 160.

  When the toner TN inside the toner cartridge 5 is consumed by repeating the toner replenishment and the remaining amount of toner in the toner replenishing unit 20 decreases below a certain amount, the downward pushing force F by the toner is lowered. On the other hand, the toner TN in the developing chamber 160 tends to stay (is easy to stagnate) in the specific region C in which the conveyance capability is locally reduced. As a result, as shown in FIG. 12, the toner TN staying in the specific region C flows back in the arrow direction U and gradually rises, and pushes up the pair of sheet members 311 and 311.

  As shown in FIG. 13, the uppermost surface of the toner TN on the developing chamber 160 side rises to a height level substantially the same as that of the toner discharge opening 300. Along with this, the pair of sheet members 311 and 311 are pushed upward, abut against the lower surfaces of the entry restricting members 320 and 320, and close the toner discharge opening 300. As a result, the backflow of the toner TN from the developing chamber 160 to the toner supply unit 20 is suppressed. Further, the free ends 314 and 314 of the pair of sheet members 311 and 311 are restricted from entering the toner supply unit 20.

  Further, when a predetermined amount or more of toner TN is supplied to the toner replenishing unit 20 by replacing the toner cartridge 5 or the like, the pair of sheet members 311 and 311 forming the backflow prevention member 310 are, as shown in FIG. The toner discharge opening 300 can be opened by bending toward the developing chamber 160 side, so that predetermined toner can be supplied.

According to the developing device 16 of the present embodiment, for example, the following effects are exhibited.
In the developing device 16 of the present embodiment, the toner discharge opening 300 for discharging the toner from the toner replenishing unit 20 is formed of a sheet member that can be bent toward the developing chamber 160 by the weight of the toner TN. A backflow preventing member 310 that prevents the backflow of toner from the developing chamber 160 to the toner replenishment unit 20 by closing the toner discharge opening 300 when the remaining amount of toner in the toner replenishment unit 20 decreases to a certain amount or less. A prevention member 310 is provided.

  Therefore, in the present embodiment, when the remaining amount of toner in the toner replenishing unit 20 decreases to a certain amount or less, and the toner replenishing pressure (pushing force) from the toner replenishing unit 20 into the developing chamber 160 decreases, The toner discharge opening 300 can be closed by the backflow prevention member 310. Accordingly, it is possible to prevent the toner TN from flowing backward from the toner receiving area inside the developing chamber 160 to the toner replenishing unit 20 through the toner discharge opening 300. Accordingly, it is possible to improve the prediction accuracy of the remaining amount of toner in the toner replenishing unit 20, and to sufficiently suppress toner loss such as replacing the toner cartridge 5 (toner replenishing unit 20) while leaving a large amount of unused toner.

  Further, in the developing device 16 of the present embodiment, the backflow prevention member 310 is formed of a pair of sheet members 311 and 311, and one end portions of the pair of sheet members 311 and 311 are opposed to each other in the toner discharge opening 300. The other ends of the pair of sheet members 311 and 311 have free ends 314 and 314 that can be bent toward the developing chamber 160 by the weight of the toner, respectively. It is composed.

  Therefore, when toner is supplied from the toner replenishing unit 20 to the developing chamber 160, the pair of sheet members 311 and 311 of the backflow prevention member 310 are opened in a double-opening manner, and the pair of sheet members 311 and 311 opened in both are The free ends 314 and 314 side bend greatly. Therefore, the inclination angle of the toner sliding surface (surface on which the toner slides) in the sheet members 311 and 311 can be made extremely large. Thereby, it is possible to ensure a sufficiently large opening area of the toner discharge opening 300. Therefore, predetermined toner replenishment can be performed smoothly and efficiently in a short time.

Further, in the developing device 16 of the present embodiment, the entry restriction members 320 and 320 that restrict the entry of the pair of sheet members 311 and 311 of the backflow prevention member 310 into the toner supply portion 20 through the toner discharge opening 300. Is provided.
Therefore, the free ends 314 and 314 of the sheet members 311 and 311 pushed up by the toner TN flowing backward from the developing chamber 160 side can be prevented from entering the toner supply unit 20. As a result, the backflow prevention function of the toner TN can be reliably achieved, and the free ends 314 and 314 of the sheet members 311 and 311 enter the toner supply unit 20 and are closed when the toner cartridge 5 is replaced, for example. It is possible to suppress the occurrence of troubles such as hindering the operation of 230 or being caught somewhere inside the toner replenishing unit 20 and being unable to return to the original state.

As mentioned above, although preferred embodiment of this invention was described, this invention can be implemented with a various form, without being limited to embodiment mentioned above.
For example, in the above embodiment, the fixed ends 313 and 313 are configured by sticking and fixing one end of the pair of sheet members 311 and 311 around the plate members 312 and 312. Not limited to. For example, the fixed ends 313 and 313 may be configured by directly attaching and fixing one end portions of the pair of sheet members 311 and 311 to the lower surfaces of the plate members 312 and 312.

The type of the image forming apparatus of the present invention is not particularly limited, and may be a copier, a printer, a facsimile, or a complex machine thereof.
Further, the sheet-shaped transfer material is not limited to paper, and may be a film sheet, for example.

Next, examples of the present invention will be described. However, the present invention is not limited to the following examples.
Common conditions in the examples and comparative examples 1 and 2 subjected to the test are as follows.
Amount of toner in developing chamber: 80 g
Amount of toner in toner cartridge: 200 g
Printing rate: 4%
Toner consumption: 40 mg / page
Toner receiving opening size: 250 mm × 150 mm

Under the above common conditions, in Example 1, a pair of sheet members having the following conditions was used as the backflow preventing member.
Thickness: 75μm
Length: 200mm
Free end length: 125mm
Width: 150mm
In Example 2, a pair of sheet members having the following conditions was used as the backflow preventing member.
Thickness: 50 μm
Length: 200mm
Free end length: 125mm
Width: 150mm
In Comparative Example 1, no backflow prevention member is used.
In Comparative Example 2, the backflow prevention member made of a rigid plate member was attached in a single-open manner.

  Under each of the above conditions, a test was performed to measure the relationship between the toner consumption (g) when the original was printed at a printing rate of 4% and the remaining amount of toner (g) inside the toner cartridge.

The results of the test were as shown in FIGS.
In the case of the embodiments (Embodiments 1 and 2), even if the remaining amount of toner in the toner cartridge is reduced, no backflow occurs from the developing chamber. The amount of toner decreased rapidly.
In the case of Comparative Examples 1 and 2, when the remaining amount of toner in the toner cartridge decreases, backflow from the developing chamber occurs, and therefore the amount of toner in the toner cartridge remains unstable and the toner in the developing chamber remains unstabilized. The amount decreased. After the toner stays in the developing chamber, the amount of toner in the toner cartridge is stabilized.

Further, when the change in the remaining amount of toner in the developing chamber until the remaining amount of toner in the toner cartridge is stabilized, the result as shown in FIG. 16 is obtained.
In the case of the examples (Examples 1 and 2), since the time until the remaining amount of toner is stabilized is short, the remaining amount of toner in the developing chamber is suppressed to a decrease of 10 g.
In Comparative Examples 1 and 2, since the time until the remaining amount of toner becomes stable is long, the remaining amount of toner in the developing chamber is reduced by 30 g. This is disadvantageous in shortening the toner replenishment time after replacement of the toner cartridge and generating replenishment fog.

  DESCRIPTION OF SYMBOLS 1 ... Printer (image forming apparatus), 2 ... Photosensitive drum (image carrier), 5 ... Toner cartridge, 6 ... Toner supply part, 8 ... Transfer roller (transfer part), 9 ... Fixing part DESCRIPTION OF SYMBOLS 10 ... Charging part, 16 ... Developing apparatus, 17 ... Developing roller (toner carrier), 18, 19 ... Spiral blade for stirring and conveying toner (toner conveying part), 160 ... Developing chamber, 162 ... Housing 220 ... Toner receiving opening 300 ... Toner discharging opening 310 ... Backflow preventing member 311 ... Sheet member 313 ... Fixed end 314 ... Free end 330 ... Ingress restricting member T ... ... paper (transfer material), TN ... toner

Claims (4)

A toner carrier for carrying toner;
A housing having a developing chamber for accommodating the toner carrier;
A toner replenishing section for replenishing toner inside the developing chamber;
A developing device provided in the developing chamber, and a toner transport unit that transports the toner in the developing chamber to the toner carrier,
The developing chamber has a toner receiving opening for receiving toner inside the developing chamber,
The toner replenishing portion has a toner discharge opening for discharging the toner from the toner replenishing portion at a position facing the toner receiving opening and above the toner receiving opening;
A backflow prevention member formed at the toner discharge opening from a sheet member capable of being bent toward the developing chamber by the weight of the toner, and the remaining amount of toner in the toner replenishing portion is reduced to a predetermined amount or less. A backflow prevention member that closes the toner discharge opening and prevents the backflow of toner from the developing chamber to the toner replenishing portion is provided,
The backflow prevention member is formed from a pair of the sheet members,
One end of each of the pair of sheet members constitutes a fixed end that is fixed to an opposite side of the toner discharge opening, and the other end of each of the pair of sheet members is in the developing chamber due to its own weight. The developing device which comprises the free end which can bend to the side. The developing device according to claim 1, wherein the toner replenishing portion constitutes a part of a toner cartridge that is detachably attached to the housing. The developing device according to claim 1, wherein the toner discharge opening is provided with an entry restricting member that restricts the backflow preventing member from entering the inside of the toner replenishing portion. A developing device according to any one of claims 1 to 3,
One or more image carriers on which an electrostatic latent image is formed, and a toner image is formed on the electrostatic latent image upon receipt of toner from the toner carrier of the developing device;
A transfer unit that directly or indirectly transfers the toner image formed on the image carrier to a sheet-like transfer material;
An image forming apparatus comprising: a fixing unit that fixes the transferred toner image to the sheet-like transfer material.

Images