JP4371348B2 - Image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image forming apparatus for recording an image on a transfer material such as a sheet / intermediate transfer member, such as a copying machine, a printer, a facsimile, or a complex machine thereof. In particular these, related to repeated charging and writing, developing, transferring and cleaning, etc. The image forming apparatus of an electrophotographic for recording on a transfer material by transferring an image formed on an image bearing member.
[0002]
[Prior art]
In an electrophotographic image forming apparatus, an electrostatic latent image is formed on an image carrier by charging and writing, and toner is attached by a developing device to develop the electrostatic latent image on the image carrier. Since the developing device consumes toner as it is used, it is usually provided with a toner detection device that detects the presence or absence of toner, and when the toner runs out, new toner is supplied from a supply toner container such as a toner bottle.
[0003]
For example, as shown in FIG. 8 , an agitator 2 is rotatably provided in the developing case 1 and a toner 3 is accommodated therein. The developing case 1 is provided with lenses 4 and 5 at opposing positions. A light emitting element 6 is disposed outside the incident side lens 4, and a light receiving element 7 is disposed outside the exit side lens 5.
[0004]
Then, light emitted from the light emitting element 6 enters the developing case 1 through the incident side lens 4, and when the toner in the developing case 1 runs out, the light passes through the toner detection position 8 in the developing case 1. Then, light is received by the light receiving element 7 through the exit side lens 5, and the toner end is detected, so that new toner is supplied to the developing device from the supply toner container.
[0005]
[Problems to be solved by the invention]
By the way, in such a developing device, the toner in the developing case 1 may float as the agitator 2 rotates and adhere to the lens surfaces of the lenses 4 and 5. Therefore, conventionally, for example, the cleaning member 9 attached to the agitator 2 is brought into sliding contact with the rotation of the agitator 2 and the lens surface is cleaned by the cleaning member 9.
[0006]
However, since the lens surface is a curved surface, it is difficult to clean the lens surface cleanly. In the conventional configuration as described above, there is a possibility that toner is erroneously detected due to poor cleaning.
[0007]
SUMMARY OF THE INVENTION Accordingly, a first object of the present invention is to provide a toner detection device used in such a developing device of an image forming apparatus, so that the toner detection surface has a shape that can be easily cleaned, and prevents erroneous detection of toner due to poor cleaning. is there.
[0008]
A second object of the present invention is to prevent a reduction in toner capacity in the toner storage container in such a toner detection device.
[0009]
A third object of the present invention is to make it possible to accurately detect toner in such a toner detection device.
[0010]
A fourth object of the present invention is to prevent toner from being erroneously detected by preventing the toner from entering the toner detection position side end portion of the light guide in such a toner detection device.
[0011]
A fifth object of the present invention is to provide a developing device provided with a toner detection device that achieves the above object.
[0012]
A sixth object of the present invention is to provide an image forming apparatus provided with a toner detection device that achieves the above object.
[0013]
[Means for Solving the Problems]
For this reason, in order to achieve the first and third objects, the invention described in claim 1 uses a light emitting element and a light receiving element in a toner storage container such as a developing case, a replenishing toner container, and a collected toner container. In an image forming apparatus including a toner detection device that detects the presence or absence of toner and fullness,
An incident-side light guide that guides light from a light-emitting element installed outside the toner container to a toner detection position in the toner container, and guides light from the toner detection position to a light-receiving element outside the toner container. With a light guide on the exit side,
Attach a lens member to the toner detection position side end of the light guide on the entrance side and the exit side
The end portions of the light guides on the toner detection position side are covered with a holder having a planar toner detection surface via the lens member, and held.
The toner detection surfaces of the holder are opposed to each other,
A cleaning member for sliding and rubbing both toner detection surfaces is provided in the toner storage container.
[0014]
According to a second aspect of the present invention, in order to achieve the second object, in the image forming apparatus according to the first aspect , the incident side and the outgoing side light guides are both formed of optical fibers. It is characterized by.
[0016]
According to a third aspect of the invention, in order to achieve the fourth object, in the image forming apparatus according to the third aspect, the light guides on the incident side and the outgoing side are held by sealing with a holder. It is characterized by.
[0019]
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 which is an example of an image forming apparatus according to the present invention.
[0020]
In the printer apparatus main body A of the illustrated color laser printer, an image carrier unit 10 is provided substantially at the center. The image carrier unit 10 is provided with an endless belt-like 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.
[0021]
Around the image carrier unit 10, a charging unit 14, a writing unit 15, a multi-stage developing unit 16, an intermediate transfer unit 17, a cleaning unit 18 and the like are provided.
[0022]
The charging unit 14 uniformly charges the surface of the image carrier 12 by applying a high voltage.
[0023]
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.
[0024]
As shown in FIG. 2 in the illustrated example, the multi-stage developing unit 16 is detachably attachable to the developing units 24K, 24C, 24M, and 24Y containing black, cyan, magenta, or yellow developer in order from the bottom. Prepare in multiple stages. Each developing unit 24 is selectively brought close to the image carrier 12, and roller-like developer carriers 25 K, 25 C, 25 M, and 25 Y provided in each developing unit 24 are in contact with or close to the image carrier 12. .
[0025]
As shown in FIG. 1, the intermediate transfer unit 17 is wound around a plurality of rollers 27 and has a belt-like intermediate transfer member 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 member 28 is provided.
[0026]
The cleaning unit 18 for the image carrier 12 presses a cleaning blade against the image carrier 12. Although not shown in the figure, the cleaning device 32 for the intermediate transfer member 28 is similarly formed by pressing a cleaning blade against the intermediate transfer member 28.
[0027]
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 to the sheet transport path 30, transported by the transport roller 36, and timed by the registration roller 37 between the intermediate transfer body 28 and the intermediate transfer roller 31. Send in towards.
[0028]
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.
[0029]
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 member 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 member 28 and the intermediate transfer roller 31 through the sheet conveyance path 30.
[0030]
On the other hand, 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 an electrostatic latent image for each color sequentially on the image carrier 12. Next, the multistage developing unit 16 electrostatically attaches toner, and visualizes each color. Each color image is transferred onto the intermediate transfer member 28 for each color, and four colors are combined to form a color image.
[0031]
The color image formed on the intermediate transfer body 28 is transferred to a sheet 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.
[0032]
The image carrier 12 after the image transfer is prepared for the next image formation by removing the transfer residual toner with the cleaning blade of the cleaning unit 18. Further, the intermediate transfer body 28 after the image transfer is also prepared for the next image formation by removing the transfer residual toner with the cleaning blade of the cleaning device 32.
[0033]
Incidentally, each developing unit 24 includes a developing device 60 and a toner cartridge 62 as shown in detail in FIG. The developing device 60 improves durability and can be used repeatedly by replacing the toner cartridge with a new one even when the toner in the toner cartridge 62 runs out.
[0034]
The developing device 60 forms a developing chamber 41 and a toner cartridge storage chamber 43 in the developing case 42. The developing chamber 41 is provided with a roller-like developer carrier 25. The developer carrier 25 faces the image carrier 12 through the opening 42a of the developing case 42, and 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.
[0035]
The developer regulating member 44 is also provided in the developing chamber 41, and as shown in FIG. 4, the shaft 45 is supported by the developing case 42 via the bearing 46, and the bearing 46 is urged by the urging member 47. It is pressed against the carrier 25. Then, it rotates in the counter direction with respect to the developer carrier 25 at the pressing position.
[0036]
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.
[0037]
The developer carrier 25 is also brought into contact with a roller-like developer supply member 50 with a predetermined nip. The developer supply member 50 is also provided in the developing chamber 41 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.
[0038]
Further, a toner stirring member 56 is provided on the back side (left side in the figure) of the developing chamber 41. In the illustrated example, the toner stirring member 56 rotates counterclockwise in the drawing.
[0039]
A toner replenishing port 42 b is opened in a boundary wall 57 between the developing chamber 41 and the toner cartridge storage chamber 43 of the developing case 42.
[0040]
On the other hand, the toner cartridge 62 is stored in the toner cartridge storage chamber 43 so that it can be pulled out from the front side. The toner cartridge 62 includes two agitators 64 on the left and right sides in the cartridge case 63, and stores black, cyan, magenta, or yellow toner, respectively. The agitator 64 may rotate in any direction, but both rotate in the counterclockwise direction in the drawing.
[0041]
The cartridge case 63 is provided with a toner supply port 63a. When the toner cartridge 62 is mounted in the toner cartridge storage chamber 43, the toner supply port 63a faces the toner supply port 42b of the boundary wall 57 described above. At this time, the seal member 65 is sandwiched between the peripheral edges of the toner supply port 63a and the toner supply port 42b.
[0042]
At the time of image recording, 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.
[0043]
The developer carrier 25 carries toner while rotating, and the charged toner is fully charged by friction with the developer regulating member 44 and is thinned by the developer regulating member 44. Then, the thinned toner is attached to the image carrier 12, and the latent image on the image carrier 12 is visualized.
[0044]
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.
[0045]
Although not shown in FIG. 3, the developing device 60 has an optimum position for detecting the toner end in the developing case (toner storage container) 42, that is, in the developing chamber 41, as shown in FIG. A toner detection device 70 having a toner detection position B is provided.
[0046]
The toner detecting device 70 is installed outside the developing case 42, and a light emitting element 71 such as a light emitting diode, and light such as infrared light from the light emitting element 71 is introduced into the developing case 42 and guided to the toner detecting position B. An incident-side light guide 72, an exit-side light guide 73 that guides light from the toner detection position B to the outside of the developing case 42, and a light-receiving element 74 such as a photodiode that receives the light guided by the light guide 73. It consists of.
[0047]
In the illustrated example, the light emitting element 71 and the light receiving element 74 are respectively attached to the front and rear side plates 75 and 76 that are provided facing the inside of the printer apparatus main body A and support the developing device 60 and the like.
[0048]
As the light guides 72 and 73, optical fibers are used in the illustrated example. Resin guides 77 and 78 are attached to the light emitting element 71 side of the incident side light guide 72 and the light receiving element 74 side of the light guide 73 on the emission side, respectively. The resin guides 77 and 78 are formed by molding using a transparent resin, and as shown in FIGS. 6A and 6B, lens surfaces 77a and 78a are provided at one end, and flange portions 77b and 78b are provided at the other end. Then, the light guides 72 and 73 are inserted into the center holes 77c and 78c, respectively, and are prevented from coming off by adhesion.
[0049]
Now, as shown in FIG. 5, the two light guides 72 and 73 are inserted into the guide mounting holes 42a of the developing case 42 from the inside of the developing chamber 41, and the flanges 77b and 78b are abutted against the developing case 42, and the lens surface. 77 a is attached to the light emitting element 71, and the lens surface 78 a is closely opposed to the light receiving element 74 and attached to the developing case 42.
[0050]
On the other hand, as shown in FIG. 7, the end portions of the light guides 72 and 73 on the toner detection position side are inserted into the center holes 80a and 81a of the lens members 80 and 81 and fixed with an adhesive. The lens members 80 and 81 are formed by molding, and the end portions are spherical surfaces to form lens surfaces 80b and 81b.
[0051]
The lens members 80 and 81 are covered with holders 82 and 83, respectively, and fixed with an adhesive. As a result, the toner detection position side ends of the light guides 72 and 73 are covered with the holders 82 and 83 through the lens members 80 and 81, respectively, and are completely sealed and held in the developing case 42. The holders 82 and 83 are made of a transparent resin material, and are provided with planar toner detection surfaces 82a and 83a.
[0052]
Then, the toner detection surfaces 82a and 83a are opposed to each other with a certain gap, the holders 82 and 83 are fixed to the developing case 42 with, for example, a double-sided tape, and the toner detection position B between the toner detection surfaces 82a and 83a is fixed. And
[0053]
With this configuration, when there is toner in the developing case 42, the light from the light emitting element 71 is guided into the developing case 42 by the light guide 72 on the incident side, but is blocked by the toner at the toner detection position B. The light is prevented from reaching the light receiving element 74 through the light guide 73 on the emission side.
[0054]
However, when the toner in the developing case 42 runs out, the light from the light emitting element 71 passes through the toner detection position B in the developing case 42 and is guided outside the developing case 42 by the light guide 73 on the emission side. The light guided by the light guide 73 is received by the light receiving element 74, and the toner end is detected.
[0055]
When the toner end is detected by the toner detection device 70, the agitator 64 shown in FIG. 3 is rotated to convey the toner in the toner cartridge 62 while stirring, and is put into the developing chamber 41 from the toner supply port 63a through the toner supply port 24b. .
[0056]
By the way, in the illustrated example, when the toner stirring member 56 rotates, a cleaning member 68 made of an elastic member such as PET attached to the toner stirring member 56 is brought into contact, and both sides of the cleaning member 68 are slidably contacted with each other. 82a and 83a are cleaned. As a result, toner sticking to the toner detection surfaces 82a and 83a and adhesion of foreign matters are prevented, toner end detection accuracy is improved, and occurrence of abnormal images due to toner replenishment delay and the like is prevented.
[0057]
In the above-described example, the toner detection device according to the present invention is applied to toner end detection in the developing case 42 of the developing device 60. When the toner in the developing case 42 runs out, the toner cartridge 62, which is a replenishing toner container, is used. The case where new toner is supplied into the developing chamber 41 has been described.
[0058]
However, the toner detection device according to the present invention is applied to the toner end detection of the replenishment toner container such as the toner cartridge 62, and when the toner in the replenishment toner container runs out, the toner end is notified and the replenishment toner container is replaced with a new one. It may be urged to exchange.
[0059]
Incidentally, the cleaning unit 18 for the image carrier 12 and the cleaning device 32 for the intermediate transfer member 28 shown in FIG. 1 are provided with a collected toner storage device for storing the recovered toner, although not shown. For example, the toner detection device according to the present invention is also applied to such a collected toner storage device. When it is detected that the collected toner storage container is full of the collected toner, this is notified and the collected toner storage is stored. You may be prompted to replace the container with a new one.
[0060]
In addition, the present invention can be used for toner detection when any one of a one-component developer consisting of only toner, a two-component developer consisting of toner and a carrier, or a wet developer is used.
[0061]
【The invention's effect】
As described above, according to the first aspect of the invention, the image forming apparatus includes the light guide on the incident side and the light guide on the output side, and the end portions on the toner detection position side of these light guides are planar. Since it is covered and held by a holder having a toner detection surface, the toner detection surfaces of the holder are opposed to each other, and a cleaning member that rubs both toner detection surfaces is provided in the toner storage container . The toner detection surface can be formed into a flat shape that is easy to clean, and for example, a cleaning member attached to the toner stirring member can be slid and cleaned to prevent erroneous detection of toner due to poor cleaning.
[0062]
According to the second aspect of the present invention, in such an image forming apparatus , since the light guides on the incident side and the light exit side are both formed by optical fibers, the light guide to be put in the toner storage container is thinned, and the toner A reduction in toner capacity in the storage container can be prevented.
[0063]
According to the first aspect of the present invention, in such an image forming apparatus, the lens member is attached to the end of the incident side and the exit side of the light guide on the toner detection position side, and the toner detection position side through the lens member. Since the end portion is covered and held by the holder, the toner can be accurately detected.
[0064]
According to the invention of claim 3 , in such an image forming apparatus, since the light guide on the incident side and the light exit side is held by sealing with the holder, the toner on the toner detection position side end of the light guide is retained. Intrusion can be prevented and toner misdetection can be prevented.
[Brief description of the drawings]
FIG. 1 is an overall schematic configuration diagram of a color laser printer which is an example of an image forming apparatus according to the present invention.
FIG. 2 is a schematic configuration diagram of the multi-stage developing unit.
FIG. 3 is a schematic configuration diagram of the first developing unit.
FIG. 4 is a diagram illustrating a state in which a developer regulating member is pressed against a developer carrying member in the developing device of the developing unit.
FIG. 5 is a schematic longitudinal sectional view of a developing device showing the toner detection device.
6A and 6B are longitudinal sectional views of one end side of a light guide provided in the toner detection device.
FIG. 7 is a longitudinal sectional view of the other end side of the light guide provided in the toner detection device.
FIG. 8 is a schematic longitudinal sectional view of a developing device including a conventional toner detection device.
[Explanation of symbols]
24 Each developing unit 42 Developing case (toner storage container)
56 toner stirring member 60 developing device 62 toner cartridge (replenishment toner container)
68 Cleaning member 70 Toner detection device 71 Light emitting element 72 Incident side light guide 73 Emission side light guide 74 Light receiving element 80 Lens member 81 Lens member 82 Holder 83 Holder 82a Toner detection surface 83a Toner detection surface B Toner detection position

Claims (3)

In an image forming apparatus comprising a toner detection device that detects toner in a toner container using a light emitting element and a light receiving element,
An incident-side light guide that guides light from the light-emitting element installed outside the toner storage container to a toner detection position in the toner storage container; and light from the toner detection position outside the toner storage container. A light guide on the output side that guides to the light receiving element
A lens member is attached to the toner detection position side end of the light guide on the entrance side and the exit side,
The end portions of the light guides on the toner detection position side are covered with a holder having a planar toner detection surface via the lens member ,
The toner detection surfaces of the holder are opposed to each other,
In the toner storage container, provided with a cleaning member for rubbing both toner detection surfaces,
Imaging equipment, characterized in that.   The image forming apparatus according to claim 1, wherein both the light guides on the incident side and the light exit side are formed of optical fibers. The image forming apparatus according to claim 1 , wherein the light guide on the incident side and the light exit side is held by sealing with the holder.

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