JP3122791B2 - Image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an electrostatic latent image formed on an image carrier by an electrophotographic method, through development, transfer and separation processes.
The present invention relates to an image forming apparatus for fixing a transfer image on a transfer material.

[Background of the Invention]

2. Description of the Related Art As image forming apparatuses such as printers and copiers have become smaller, lighter, and more sophisticated, the density and complexity of image forming apparatuses have been increasing.

2. Description of the Related Art In a commonly used image forming apparatus (an electrophotographic copying machine, a laser printer, a facsimile, or the like), the outer shape of the apparatus main body is configured as a compact rectangular parallelepiped.

For example, in a laser printer, an image carrier (photosensitive drum or photosensitive belt), a charger, a developing device for developing a document image with toner, a transfer device for transferring a toner image to a transfer material, an image carrier A cleaning device and the like for removing and cleaning residual toner on the body surface are arranged, and constitute an image forming unit.

On the other hand, the lower stage includes a paper cassette receiving unit for mounting a paper cassette for accommodating transfer materials of various sizes, a paper feeding unit, a conveying unit, a fixing device for fixing a toner image on the transfer material, and a paper discharging unit. Have been placed.

In addition, a toner replenishing device that accommodates toner for replenishment and replenishes the developer in a timely manner is disposed near the developing device.

In such an image forming apparatus, in order to easily perform maintenance and inspection, an image carrier, a charger,
A drum mount unit in which a developing device, a cleaning device, and the like can be integrally pulled out, and a process cartridge that can be replaced are used.

On the other hand, devices other than the image forming section, such as a fixing device, can be easily opened for jamming of a transfer material, cleaning and maintenance, and the like. Also, the toner supply device is
In general, it is arranged near the front side on the operation side to facilitate toner supply.

[Problems to be solved by the invention]

In such an image forming apparatus, since the fixing device and the toner replenishing device are located relatively close to each other, radiant heat or radiant heat generated from the fixing device, convective heat in the apparatus main body, and members in the apparatus main body are used. Due to heat conduction and the like, the toner contained in the toner hopper of the toner replenishing device aggregates,
There is a problem that uniform toner supply to the developing device becomes impossible, and a clear recorded image having an appropriate density cannot be obtained.

[Means for solving the problem]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an image forming apparatus which can always obtain a stable and clear recorded image by eliminating the above-mentioned problems and supplying toner uniformly.

In order to achieve the above object, the present invention provides an image forming unit that includes an image carrier and a developing device, forms a toner image on the image carrier, a paper feed cassette that stores a transfer material, Replenishing device, a transfer unit for transferring the toner image formed on the image carrier onto a transfer material fed from the paper feed cassette, and a transfer material for transferring the toner image transferred by the transfer unit. In an image forming apparatus having a fixing device for fixing the toner image thereon, and a paper discharge unit from which the transfer material fixed by the fixing unit is discharged, a toner supply device is provided in an upper part of the image forming apparatus, and a paper discharge unit is provided. This is achieved by a configuration provided at a position facing the fixing device with respect to the fixing device.

〔Example〕

Next, the present invention will be described based on an embodiment shown in the accompanying drawings.

FIG. 1 is a left side view of a main cross-sectional view of a color printer to which the present invention is applied. FIG. 2 is a perspective view of the printer in an open state. The apparatus main body 10 is surrounded by an operation panel 11 and an openable / closable upper cover 12, a toner supply cover 13, a front cover 14, and the like on its front face, and a detachable process cartridge 15 and a paper feed cassette 16 are provided inside. I have.

The process cartridge 15 includes a photosensitive belt 17 and a developing device.
23a, 23b, 23c, 23d, charging device 21, cleaning device 25
And so on.

The photoreceptor belt 17 serving as an image carrier has a flexible belt surface coated with a photosensitive layer such as an organic photoconductive layer (OPC), and is stretched between a driving roller 18 and a conventional roller 19. It is turned clockwise.

Around the photoreceptor belt 17, a charging unit, an exposure unit, a developing unit, a transfer unit, and a cleaning device are provided.

The charging means is an existing charger 21 such as a corona charger or a scorotron charger.

The developing means is a plurality of developing units 23a, 23b, 23cb, and 23d each containing a developer of a different color, for example, a toner (developer) of each color of yellow, magenta, cyan, and black. Each of these developing units 23a to 23d has a function of visualizing the electrostatic latent image on the photosensitive belt 17 into a toner image by a non-contact developing method.

The cleaning blade of the cleaning device 25 is kept at a position separated from the surface of the photoreceptor belt 17 during the image forming process, and is brought into pressure contact with the surface of the photoreceptor belt 17 only during cleaning after transferring the toner image to the transfer material P. Belt 17
To clean.

The toner collection box 26 collects and stores the residual toner on the photoreceptor belt 17 removed by the cleaning device 25.

In the present embodiment, the respective process units of the photoreceptor belt 17, the charging unit 21, the developing units 23a to 23d containing the respective color toners, the cleaning device 25, and the toner collection box 26 constituting the image forming unit of the printer described above are integrated. The unit is housed in a process cartridge 15 and unitized, and the front cover 14 of the apparatus main body 10 can be opened and closed as shown by a dotted line, and can be collectively attached and detached.

On the other hand, on the image forming apparatus main body side, at a position where the process cartridge 15 is mounted and an image can be formed, an exposure unit, a transfer unit and the like are arranged around the photosensitive belt 17.

The exposing means is a semiconductor laser writing optical system unit (hereinafter referred to as an optical system unit) 22, which exposes the surface of the photosensitive belt 17 charged by the charger 21 to form an electrostatic latent image.

The transfer unit transfers the toner image formed on the photoreceptor belt 17 to the transfer material P by a transfer unit 24 such as a transfer corona discharger.
Transfer to the top.

The process of forming a color image by the color image forming apparatus having the above configuration is performed as follows.

First, the process cartridge 15 is attached to the image forming apparatus main body 10.
And is in a state where image formation is possible. When an image signal of a first color output from an image reading apparatus separate from the apparatus main body 10 is input to the optical system unit 22, a laser beam is generated by a semiconductor laser in the optical system unit 22. . The laser beam is rotationally scanned by a polygon mirror rotated by a drive motor, passes through an fθ lens, a cylindrical lens, and a group of mirrors, and is uniformly charged in advance to a predetermined electrification by a charger 21 at a peripheral surface of the photosensitive belt 17. Projected onto it to form a bright line.

On the other hand, in the sub-scanning direction, a belt index (not shown) corresponding to a specific position of the photoreceptor belt 17 is detected, or a print command signal is received, and the detection or the command signal is used as a reference. The main scanning line at which the modulation of the semiconductor laser by the image signal is started is determined. When the scanning is started, a laser beam is detected by an index sensor (not shown) in the main scanning direction, and the modulation of the semiconductor laser by the image signal of the first color is started based on the detected signal. The modulated laser beam scans the surface of the photoreceptor belt 17. Therefore, a latent image corresponding to the first color is formed on the surface of the photosensitive belt 17 uniformly charged by the main scanning by the laser beam and the sub-scanning by the conveyance of the photosensitive belt 17. This latent image is developed by a developing unit 23a containing yellow toner corresponding to the first color in the developing unit, and a yellow toner image is formed on the surface of the photoreceptor belt 17. Then photoreceptor belt 17
After passing under the cleaning blade 251 which is separated from the surface of the photoreceptor belt 17 while holding the yellow toner image on the surface thereof, the second color image is formed.

That is, the photoreceptor belt 17 on which the yellow toner image is formed is uniformly charged again by the charger 21,
Is input to the optical system unit 22, and writing is performed on the surface of the photoreceptor belt 17 to form a latent image, as in the case of the first color image signal described above.
Latent image developing device containing magenta toner as second color
Developed by 23b. The magenta toner image is formed in the presence of the already formed yellow toner image.

Similarly, a cyan toner image is formed by the developing device 23c that contains the cyan toner after forming the latent image based on the third color image signal, and further contains the black toner after forming the latent image based on the fourth color image signal. The black toner image is superimposed on the surface of the photoreceptor belt 17 by the developing unit 23d to form a color toner image on the surface of the photoreceptor belt 17.

A DC or further AC bias is applied to the developing sleeves of these developing units 23a to 23d, and the developing belt is contactlessly contacted with the photosensitive belt 17 whose base is grounded (jumping phenomenon).
Is performed. Incidentally, for the non-contact development, either a one-component development system or a two-component development system can be used. When the one-component developing method is used, the size can be reduced, but the two-component developing method is more preferable in terms of color reproduction because the two-component developing method is superior in terms of development stability.

The color toner image formed on the surface of the photoreceptor belt 17 as described above is transferred onto the transfer material P synchronized with the color toner image by the timing roller 28 supplied from the paper supply cassette 16 by the paper supply roller 27. Is done.
The transfer unit 24 performs transfer by applying a high-voltage power output having a polarity opposite to that of the toner.

The transfer material P on which the color toner image has been transferred is
The photoreceptor belt 17 that changes direction rapidly (small radius of curvature) along the drive roller 18 is surely separated by the photoreceptor belt 17 and is conveyed upward by the conveyance belt 29. Then, after the transfer material P is melted and fixed with the toner by the heat and pressure of the fixing roller 301 and the pressure roller 302 of the fixing device 30, the paper discharge roller 31 forms the upper cover 12, which also serves as a paper discharge tray (paper discharge part). It is discharged to the upper surface.

The fixing device 30 includes a fixing roller 301 driven and rotated by incorporating a heater, a pressure roller 302 driven and rotated by the fixing roller 301 and a spring for urging and pressing, and a pressure contact with a peripheral surface of the fixing roller 301. Cleaning roller 303, temperature sensor 304 for measuring the peripheral surface temperature of fixing roller 301, separation claw
305, a guide plate 306. The peripheral surface temperature of the fixing roller 301 is controlled so as to be constantly maintained at about 200 ° C.

The fixing device 30 is installed above the proximity of the process cartridge 15 and the transfer device 24 (upper left in the drawing) and above the apparatus main body 10 near the vibration root of the upper cover 12.

In FIG. 1, when a jam detection sensor S1, S2, S3, S4 provided on the transfer path of the transfer material P and a jam determination unit (not shown) detects a jam of the transfer material P, a lock means (not shown) is opened. Then, the upper cover 12 is opened. Further, the upper cover 12 is largely vibrated upward by a manual operation to bring the upper cover 12 into a fully opened state. The transfer material P causing the jam can be found and removed from the upper opening of the apparatus main body 10 thus opened.

When the upper opening is fully opened, the fixing device 30
It is possible to easily perform maintenance and inspection such as removal of jammed paper inside and in the vicinity, cleaning of the fixing roller 301 and the pressure roller 302, and replacement of the cleaning roller 303.

Further, an exhaust fan means (not shown) is provided on the side or rear of the fixing device 30, and heat generated from the fixing device 30 is exhausted to the outside through an opening 101 (see FIG. 2) of the apparatus main body 10. You.

Since the fixing device 30 is disposed at the uppermost part of the apparatus main body 10, radiant heat and radiant heat generated from the fixing device 30 are easily radiated out of the apparatus from the upper cover 12 and the wall surface above the apparatus main body 10. Further, the air is forcibly discharged from the apparatus by the exhaust fan means. Further, it is hardly affected by thermal convection in the apparatus main body 10.

On the other hand, toner replenishing devices 35a, 35b, 35c, and 35d are arranged at the upper right of the process cartridge 15 in the figure.
The toner replenishing devices 35a to 35d include four toner hoppers 351a, 351b, which respectively store toners of different colors, for example, yellow, magenta, cyan, and black toners.
351c, 351d, and opening and closing devices 352a-3 provided at the upper opening thereof
52d, and toner supply tubes 353a to 353d connected to the developing units 23a to 23d, respectively. A toner stirring member 354a and a toner supply screw 355a are rotatably provided in the toner hopper 351a. The same applies to the other toner hoppers 351b, 351c, 351d.

The toner stirring members 354a to 354d, the toner supply screws 355a to 355d, and the spiral screws in the toner supply tubes 353a to 353d are all intermittently driven by the drive sources and the clutches of the developing devices 23a to 23d.

Note that a toner supply cover 13 is supported above the opening / closing devices 352a to 352d so as to be freely opened and closed.

The above-described toner replenishing devices 35a to 35d are arranged at the uppermost portion of the apparatus main body 10, and are located at a position facing the fixing device 30 with the sheet discharge tray portion of the upper cover 12 interposed therebetween. The generated heat does not heat the toner hoppers 351a to 351d. Therefore, the toners of the respective colors accommodated in the toner hoppers 351a to 351d do not aggregate to form a toner mass or the toner layer does not become hollow.

FIG. 3 is a sectional view showing another embodiment of the image forming apparatus according to the present invention. Note that, in the reference numerals used in the drawings, parts having the same functions as those in FIG. 1 are denoted by the same reference numerals. Further, points different from the above embodiment will be described.

This embodiment is an image forming apparatus in which a process cartridge 40 using a photosensitive drum 41 as an image carrier is movable. In the process cartridge 40, in addition to the photosensitive drum 41, a charger 42, developing units 43a, 43b, 43c, 43d,
A cleaning device 44 is provided and unitized.

At the upper left of the process cartridge 40 in FIG.
The fixing device 30 is disposed at the top of the fixing device 30. A toner replenishing device 35 is disposed in the upper right of the process cartridge 40 in the figure and near the uppermost right end of the apparatus main body 10, and is located at a position facing the paper discharge tray of the upper cover 12 with the middle therebetween. By arranging the fixing device 30 and the toner replenishing device 35 at the most remote distance in this manner, the toner accommodated in the toner hopper is not affected by the heat generated by the fixing device 30.

In the above-described embodiment, as the image forming process, the image forming method in which a color toner image is formed on the photoreceptor belt 17 and then transferred to the transfer material at one time has been described. A color image forming method in which toner images are transferred in an overlapping manner may be used. Although the non-contact developing method has been described as a developing method, the present invention is not limited to this non-contact developing method, but can be applied to contact developing.

Further, the process cartridge 15 is not limited to the inclined arrangement shown in FIG. 1, but may be configured to be movable in a horizontal arrangement.

Further, the image forming apparatus of the present invention is not limited to a color printer or the like in which the multi-color process cartridge 15 is mounted, but is applicable to a monochrome printer or the like.

〔The invention's effect〕

As described above, in the image forming apparatus of the present invention, by providing the sheet discharge unit of the image forming apparatus between the toner replenishing device and the fixing device, the heat in direct contact with the outside air of the sheet discharge unit is provided. It can be diffused, and the effect of heat generated from the fixing device can be reduced. Therefore, the toner accommodated in the toner hopper does not form a solidified mass, or does not become hollow in the hopper to form a bridge,
The developer in the developing device always has an appropriate toner density, and an image forming apparatus capable of stably recording a high-quality image is provided.

[Brief description of the drawings]

FIG. 1 is a side sectional view of an image forming apparatus of the present invention, FIG. 2 is a perspective view of the image forming apparatus, and FIG. 3 is a side sectional view of an image forming apparatus having a photosensitive drum to which the present invention is applied. is there. 10 Apparatus body, 12 Top cover 13 Toner supply cover 15, 40 Process cartridge 16 Paper cassette 17 Photoconductor belt (image carrier) 22 Optical units 23a to 23d , 43a to 43d: developing unit 24: transfer unit, 30: fixing device 31: discharge rollers 35a to 35d: toner replenishing device 41: photosensitive drum (image carrier) 301: fixing roller, 302 pressure roller 303 cleaning roller 304 temperature sensor 305 separation claw 306 guide plates 351 a to 351 d toner hopper 352 a to 352 d opening / closing device 353 a to 353 d toner supply tube 354 a To 354d: toner stirring member 355a to 355d: toner supply screw P: transfer material

────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Masakazu Fukuchi 2970 Ishikawa-cho, Hachioji-shi, Tokyo Konica Co., Ltd. Examiner, Masahisa Kunida (56) References JP-A-62-42169 (JP, A) JP-A Sho JP-A-2-249842 (JP, A) JP-A-58-52559 (JP, U) JP-A-57-116967 (JP, U) JP-A-62-84050 (JP, A) U) Shokai Sho 56-120558 (JP, U) Shokai Sho 63-185148 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 15/00 550 G03G 15/08 G03G 15/20 G03G 21/16-21/18 G03G 15/00 510 G03G 15/00 530

Claims (4)

(57) [Claims] An image forming means for forming a toner image on the image carrier; a sheet cassette for accommodating a transfer material; and supplying toner to the developing device. A toner supply device, a transfer unit that transfers a toner image formed on the image carrier onto a transfer material fed from the paper feed cassette, and a toner image transferred by the transfer unit onto a transfer material. An image forming apparatus having a fixing device for fixing the toner image, and a sheet discharge unit from which the transfer material fixed by the fixing unit is discharged, wherein the toner replenishing device is an upper part of the image forming device, and An image forming apparatus provided at a position facing the fixing device with the sheet discharging portion interposed therebetween. 2. The image forming apparatus according to claim 1, wherein the toner replenishing device is provided on an upper side of the image forming apparatus on an upstream side with respect to a sheet feeding direction from the sheet feeding cassette. The image forming apparatus according to claim 1, further comprising the fixing device. 3. The image forming means is housed in a process cartridge detachable from the image forming apparatus main body, and is provided between the toner supply device and the paper feed cassette. The image forming apparatus according to claim 1, wherein the image forming apparatus is configured to perform the image forming process from a front side of the image forming apparatus, which is an upstream side with respect to a sheet feeding direction from a sheet feeding cassette. 4. An image forming apparatus comprising: a plurality of developing devices; and a plurality of toner replenishing devices for replenishing toner to each of the plurality of developing devices. The image forming apparatus according to claim 1, wherein the image forming apparatus is provided at right angles to a sheet feeding direction from a cassette.