JP4674837B2 - Developing device and image forming apparatus having the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image forming apparatus that records an image on a sheet such as a sheet or an OHP film, such as a copying machine, a printer, a facsimile, or a complex machine thereof. In particular, the present invention relates to an electrophotographic image forming apparatus for transferring an image formed on an image carrier by repeating charging, writing, developing, transferring, cleaning, etc. and recording the image on a sheet. The present invention also relates to a developing device for developing an electrostatic latent image formed on the surface of an image carrier in such an electrophotographic image forming apparatus.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, in an electrophotographic image forming apparatus, a developing device is usually provided with a toner end detection unit that detects whether toner is abundant as one of toner detection units.
[0003]
In the toner end detection means, for example, an incident side light guide that guides the light of the light emitting diode into the developing device, and an emission side light guide that guides the light in the developing device to the photodiode outside the developing device, are provided. There is a type in which tip detection surfaces of the light guides are opposed to each other with a certain gap at a predetermined detection position in the developing device.
[0004]
In this type of toner end detection means, when the light of the light emitting diode passes through both detection surfaces at the detection position and reaches the photodiode, the toner end is detected and the developing device is replenished with toner.
[0005]
[Problems to be solved by the invention]
However, in such a toner end detection means, the toner may stick to the detection surface in the toner or foreign matter such as paper dust may adhere to the detection surface. There was a problem that the toner supply was delayed and an abnormal image was generated.
[0006]
SUMMARY OF THE INVENTION Accordingly, a first object of the present invention is to improve toner detection accuracy by preventing toner from sticking to a detection surface of a toner detection unit such as a toner end detection unit and adhesion of foreign matter in a developing device of an image forming apparatus. There is to do.
[0007]
The second object of the present invention is to enable the detection surface to be cleaned with a simple configuration.
[0008]
A third object of the present invention is to improve the contact of the cleaning portion with the detection surface and to enable the detection surface to be cleaned more reliably.
[0009]
A fourth object of the present invention is to make it possible to clean the detection surface more reliably by eliminating escape of the cleaning portion.
[0010]
The fifth object of the present invention is to improve the durability of the cleaning part.
[0011]
A sixth object of the present invention is to provide an image forming apparatus provided with a developing device that achieves the above object.
[0012]
[Means for Solving the Problems]
Therefore, in order to achieve the above first to third objects, the invention described in claim 1 is a developing device having a toner stirring means and a toner detection means, and the toner stirring means is provided with a flexible toner paddle. A slit is formed in the toner paddle in a direction perpendicular to the rotation axis of the toner stirring means, and a cleaning portion is formed in a tongue shape with a part of the toner paddle. While making multiple vertical cuts to divide both sides of the cleaning part into multiple parts,
The toner detection means has a detection surface composed of lens surfaces facing each other with a predetermined interval, and the detection surface of the toner detection means is arranged in the rotation path of the toner paddle so as to be slidable on both sides of the cleaning portion and cleaned. It is characterized by.
[0015]
According to a second aspect of the present invention, in order to achieve the fourth object, in the developing device according to the first aspect, a reinforcing means for reinforcing the cleaning portion upstream of the cleaning portion in the rotational direction of the toner paddle. It is characterized by providing.
[0017]
According to a third aspect of the present invention, in order to achieve the sixth object, the image forming apparatus includes the developing device according to the first aspect.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows an overall schematic configuration of a color laser printer according to the present invention.
[0019]
In the printer apparatus main body A of the illustrated color laser printer, a photoconductor unit 10 is provided substantially at the center. The photoreceptor unit 10 is provided with an endless belt-shaped image carrier 12 that is wound around a plurality of rollers 11. An organic photosensitive layer is formed on the surface of the image carrier 12.
[0020]
Around the photosensitive unit 10, a charging unit 14, a writing unit 15, a developing unit 16, an intermediate transfer unit 17, a cleaning unit 18 and the like are provided.
[0021]
The charging unit 14 uniformly charges the surface of the image carrier 12 by applying a high voltage.
[0022]
The writing unit 15 emits laser light from a laser diode (not shown) based on a color image signal from a computer, for example, and emits the laser light through a polygon mirror 20, an f / θ lens 21, a plurality of reflection mirrors 22 and the like. Thus, writing corresponding to the image signals of black, cyan, magenta, and yellow is performed to form an electrostatic latent image on the image carrier 12.
[0023]
As shown in FIG. 2 in the illustrated example, the developing unit 16 includes, in order from the bottom, developing devices 24K, 24C, 24M, and 24Y that store black, cyan, magenta, and yellow developers in a detachable multi-stage manner. Prepare. Each developing device 24 is selectively brought close to the image carrier 12, and roller-like developer carriers 25K, 25C, 25M, 25Y provided in each developing device 24 can be brought into contact with or close to the image carrier 12. And
[0024]
As shown in FIG. 1, the intermediate transfer unit 17 has an intermediate transfer belt 28 that is wound around a plurality of rollers 27. Similar to the image carrier 12, an organic photosensitive layer is formed on the surface of the endless intermediate transfer belt 28. In addition, an intermediate transfer roller 31 is provided around the sheet conveyance path 30, and a cleaning device 32 for the intermediate transfer belt 28 is provided.
[0025]
The cleaning unit 18 for the image carrier 12 presses a cleaning blade against the image carrier 12. Similarly, the cleaning device 32 for the intermediate transfer belt 28 also presses the cleaning blade against the intermediate transfer belt 28.
[0026]
By the way, a paper feed cassette 34 is attached to the bottom of the printer apparatus main body A of the laser printer so as to be freely inserted and removed. The sheet in the paper feed cassette 34 is fed out by the rotation of the paper feed roller 35, sent into the sheet transport path 30, transported by the transport roller 36, and timed by the registration roller 37 and the intermediate transfer belt 28 and the intermediate transfer roller 31. Send it in between.
[0027]
A discharge roller 39 is provided downstream of the sheet conveyance path 30 following the fixing unit 38. Further, on the printer apparatus main body A, a paper discharge stack unit 40 for stacking recorded sheets face down is provided.
[0028]
When recording is performed with this laser printer, the rollers 11 and 27 are rotated to rotate and convey the image carrier 12 and the intermediate transfer belt 28 in the directions indicated by the arrows in the drawing, and the sheet feeding roller 35 is rotated to rotate the sheet. Is fed between the intermediate transfer belt 28 and the intermediate transfer roller 31 through the sheet conveyance path 30.
[0029]
Then, the surface of the image carrier 12 is charged by the charging unit 14, and writing is performed by the writing unit 15 to form electrostatic latent images on the image carrier 12 for each color sequentially. Next, the developing unit 16 electrostatically attaches a developer charged to a charge opposite to that of the electrostatic latent image, and visualizes each color. Each color image is transferred onto the intermediate transfer belt 28 for each color by applying a charge opposite to that of the developer, and four colors are combined to form a color image.
[0030]
The color image formed on the intermediate transfer belt 28 is transferred onto the sheet by applying an opposite charge to the developer by the intermediate transfer roller 31. After the image is transferred, the transfer image is fixed by the fixing unit 38, and then discharged by the discharge roller 39 onto the discharge stack unit 40 and stacked there.
[0031]
The image carrier 12 after the image transfer is prepared for the next image formation by removing the transfer residual developer with the cleaning blade of the cleaning unit 18. Further, the intermediate transfer belt 28 after image transfer is also prepared for the next image formation by removing the transfer residual developer with the cleaning blade of the cleaning device 32.
[0032]
By the way, each developing device 24 includes a developing device 24a and a toner cartridge 24b as shown in FIG. The developing unit 24a has improved durability, and can be used repeatedly by replacing the toner cartridge with a new one when the toner in the toner cartridge 24b runs out.
[0033]
The developing device 24 a is provided with an opening 43 in the developing case 42, and a roller-shaped developer carrier 25 is provided through the opening 43 so as to face the image carrier 12. The developer carrier 25 rotates in the same direction as the image carrier 12 at the opposed position. A roller-shaped developer regulating member 44 is pressed against the developer carrier 25.
[0034]
As shown in FIG. 4, the developer regulating member 44 supports the shaft 45 by the developing case 24 via a bearing 46, and the bearing 47 is urged by the urging member 47 and pressed against the developer carrier 25. It becomes. Then, it rotates in the counter direction with respect to the developer carrier 25 at the pressing position.
[0035]
As shown in FIG. 3, the tip of the scraping member 48 is pressed against the developer regulating member 44. The scraping member 48 scrapes off the developer attached to the surface of the developer regulating member 44.
[0036]
Further, the developer supply member 50 is brought into contact with the developer carrier 25 with a predetermined nip. The developer supply member 50 is in the form of a roller and is made of a foam material 51 such as polyurethane, silicon, EPDM, and polycarbonate, and a metal cored bar 52. The contact position may be in any direction, but in the illustrated example, it rotates in the counter direction with a relative linear velocity difference with respect to the developer carrier 25. A partition plate 54 is provided below the developer supply member 50.
[0037]
A toner stirring member 56 is provided on the back side (left side in the figure) of the developing case 42. In the illustrated example, the toner stirring member 56 rotates counterclockwise in the drawing.
[0038]
In the toner cartridge 24b, two toner agitation means 57 having a toner paddle are provided. The toner stirring means 57 may rotate in any direction, but in the illustrated example, it rotates in the counterclockwise direction in the drawing. The toner cartridge 24b contains black, cyan, magenta, or yellow developer.
[0039]
When developing the latent image on the image carrier 12 with the developing unit 16, the toner agitating means 57 of the toner cartridge 24B is rotated to convey the developer while being agitated and put into the developing device 24a. In the developing device 24 a, the developer is conveyed while being agitated by the toner agitating member 56, pumped up onto the partition plate 54, and attached to the developer supply member 50. The developer supply member 50 is preliminarily triboelectrically charged by rubbing the developer while rotating, and is supplied to the developer carrying member 25 by coulomb force.
[0040]
The developer carrier 25 carries the developer while rotating, and the charged developer is charged by friction with the developer regulating member 44 and is thinned by the developer regulating member 44. Then, the latent image on the image carrier 12 attached to the image carrier 12 is visualized.
[0041]
In the illustrated example, a belt-shaped image carrier 12 is used. However, if the surface hardness of the developer carrier 25 is kept low, a drum-shaped image carrier 12 can be used.
[0042]
As shown in FIGS. 3 and 5, the toner agitating means 56 in the developing device 24 in the illustrated example is prevented from coming off by a retaining ring 60 and rotatably attached to the developing case 42. A plurality of engaging protrusions 62 are aligned on the outer periphery of the rotating shaft 61, and a rod-like reinforcing means 63 is erected in the radial direction at the center of the outer periphery.
[0043]
Then, the engagement protrusion 62 is inserted into the engagement hole 64 and latched, the proximal end side of the toner paddle 65 is wound around the rotation shaft 61, the distal end side is extended in the tangential direction, and the inner surface of the developing case 42 is slid. Make contact. The toner paddle 65 is made of a flexible sheet material such as Mylar, and the plurality of engagement holes 64 are arranged in the base end side, and two slits 66 are inserted in the center of the tip end side in parallel. A tongue-like cleaning part 67 is formed in part.
[0044]
The cleaning unit 67 is provided with the reinforcing means 63 described above on the upstream side in the rotation direction of the toner paddle 65.
[0045]
As shown in FIG. 5, the developing device 24 is provided with toner end detecting means 70 for detecting that the toner in the developing case 42 has run out.
[0046]
The toner end detection means 70 includes a light emitting diode 71 provided outside the developing case 42, an incident side light guide 72 that guides the light from the light emitting diode 71 into the developing case 42, and the light inside the developing case 42 outside the developing case 42. The light guide 73 on the emission side that leads to the light guide, and a photodiode 74 that puts light from the light guide 73.
[0047]
The light guides 72 and 73 are provided with detection surfaces 75 and 76 at the tips of the lens surfaces, respectively, which are opposed to each other with a predetermined gap between them and set as a toner detection position 77. Then, the detection surfaces 75 and 76 of the toner end detection means 70, that is, the toner detection position 77 are arranged in the rotation locus of the toner paddle 65 as shown in FIG.
[0048]
As a result, when there is toner in the developing device 24, the light from the light emitting diode 71 is guided into the developing case 42 by the light guide 72 on the incident side, but the light is blocked by the toner at the toner detection position 77 and emitted. The light guide 73 is prevented from reaching the photodiode 74 through the side light guide 73.
[0049]
However, when the toner in the developing device 24 runs out, the light from the light emitting diode 71 passes through the toner detection position 77 and reaches the photodiode 74 from the light guide 73 on the emission side, thereby detecting the toner end. it can.
[0050]
By the way, according to the present invention, when the toner agitating means 56 rotates, the cleaning portion 67 formed by a part of the toner paddle 65 is brought into contact, and both sides of the cleaning portion 67 are slid to contact the detection surfaces 75 and 76. to clean up. As a result, toner sticking to the detection surfaces 75 and 76 and adhesion of foreign matters can be prevented, toner end detection accuracy can be improved, and occurrence of abnormal images due to toner replenishment delay or the like can be prevented.
[0051]
At this time, the reinforcing means 63 provided downstream of the cleaning portion 67 is reinforced to eliminate the clearance of the cleaning portion 67, and even when toner or foreign matter is stuck, it can be removed, and the detection surface is more reliably cleaned. be able to.
[0052]
Here, as shown in FIG. 6, when the cuts 68 are made on both sides of the tongue-shaped cleaning part 67 and the both sides are divided into a plurality of parts, the contact of the cleaning part 67 with the detection surfaces 75 and 76 is improved. The detection surfaces 75 and 76 can be more reliably cleaned.
[0053]
Further, as shown in FIGS. 7 and 8, a pair of guide members 80 are attached to the developing case 42 so that the rotating cleaning portion 67 is guided between the opposing detection surfaces 75 and 76 by the guide members 80. By doing so, the detection surfaces 75 and 76 can be more reliably cleaned.
[0054]
In the example described above, the cleaning portion 67 is formed by a part of the toner paddle 65 of the toner stirring means 56. However, as shown in FIG. 9, the toner agitation means 56 is provided with a toner paddle 65 and a cleaning member 82 separate from the toner paddle 65, and the detection surface of the toner end detection means 70 is in sliding contact with the cleaning member 82. 75 and 76 may be cleaned. By doing so, the durability of the cleaning member 82 can be improved by forming it separately from the stressed toner paddle 65, preferably with a different material.
[0055]
【The invention's effect】
As described above, according to the first aspect of the present invention, in the developing device of the image forming apparatus, the toner agitation unit is provided with the flexible toner paddle, and the cleaning portion is formed by a part of the toner paddle. Since the detection surface of the toner detection means is cleaned by sliding the cleaning part, toner sticking to the detection surface and adhesion of foreign matter are prevented, and the toner detection accuracy is improved, for example, an abnormal image caused by a delay in toner replenishment, etc. Can be prevented.
[0056]
In addition , since the cleaning portion is formed in a tongue shape by slitting the toner paddle, the detection surface can be cleaned with a simple configuration.
[0057]
Further , since the both sides of the tongue-shaped cleaning part are cut and divided into a plurality of parts, the contact of the cleaning part with the detection surface can be improved and the detection surface can be cleaned more reliably.
[0058]
According to the second aspect of the present invention, since the reinforcing means for reinforcing the cleaning portion is provided upstream of the cleaning portion in the rotation direction of the toner paddle, the reinforcing portion is reinforced to eliminate the clearance of the cleaning portion. Even when foreign matters are stuck, they can be removed, and the detection surface can be more reliably cleaned.
[0060]
According to the third aspect of the present invention, it is possible to provide an image forming apparatus including the developing device having the above-described effects.
[Brief description of the drawings]
FIG. 1 is an overall schematic configuration diagram of a color laser printer according to the present invention.
FIG. 2 is a schematic configuration diagram of the developing unit.
FIG. 3 is a schematic configuration diagram of the first developing device.
FIG. 4 is a view showing a state in which the developer regulating member is pressed against the developer carrying member in the developing device.
FIG. 5 is a schematic plan view of a toner stirring means portion showing the toner end detection means.
FIG. 6 is a partially enlarged view of a toner paddle showing another example of the detection surface cleaning unit.
FIG. 7 is a schematic configuration diagram illustrating another example of the developing device.
FIG. 8 is a schematic plan view of a toner agitation unit showing another example of detection surface cleaning.
FIG. 9 is a schematic configuration diagram illustrating still another example of the developing device.
[Explanation of symbols]
24 Developing device 56 Toner stirring means 61 Rotating shaft 63 Reinforcing means 65 Toner paddle 66 Slit 67 Cleaning portion 68 Notch 70 Toner end detecting means 72 Incident side light guide 73 Emission side light guide 75 Incident side detection surface 76 Emission side detection surface 76 Detection surface 77 Toner detection position 82 Cleaning member

Claims (3)

In the developing device having the toner stirring means and the toner detection means,
The toner stirring means is provided with a flexible toner paddle, and a slit is formed in the toner paddle in a direction perpendicular to the rotation axis of the toner stirring means so that a cleaning portion is formed in a tongue-like shape at a part of the toner paddle. While forming a plurality of cuts in a direction perpendicular to the slit on both sides of the tongue-shaped cleaning part, and dividing the both sides of the cleaning part into a plurality of parts,
The toner detection means has a detection surface composed of lens surfaces facing each other at a predetermined interval, and is detected by the toner detection means in the rotation locus of the toner paddle so as to be slidable on both sides of the cleaning portion. A developing device in which a surface is arranged. The developing device according to claim 1, further comprising a reinforcing unit that reinforces the cleaning unit upstream of the cleaning unit in the rotation direction of the toner paddle.   An image forming apparatus comprising the developing device according to claim 1.

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