JP2878323B2 - Image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION "Industrial application field" The present invention can be suitably used for a color electrophotographic copying machine and a developing device of a color recording apparatus constituting an output unit such as a computer and a facsimile. The present invention relates to a developer or toner replenishing device (hereinafter, simply referred to as a "toner replenishing device" in the present invention). To a toner replenishing device of a developing device which is moved to a predetermined position to perform development.

[Background Art] In recent years, the demand for color copying has rapidly increased not only in the special field but also in the field of general affairs, and there is a demand for a color copying machine that can be used by anyone as well as experts. At present, as a color copying machine, a full-color electrophotographic copying machine utilizing electrophotographic technology is generally widely used.

Full color electrophotographic copying machines still have various problems to be solved or improved, one of which is
That is, in a developing device that visualizes an electrostatic latent image of each color formed on a photoreceptor, what kind of configuration supplies toner or developer to each developing unit.

Conventionally, various means have been proposed as a developing device for a color electrophotographic copying machine, but they are roughly classified into two types. One of them is a side-by-side developing device in which a plurality of developing units having developers of respective colors are arranged in parallel along the surface of a photoreceptor, and is currently most frequently used.

In a commercially available electrophotographic copying machine, since the photoconductor is usually a cylindrical drum, each developing device of the developing device is arranged close to the surface of the photoconductor drum and is arranged in parallel along the circumferential direction of the photoconductor drum. Be placed.

The second type is a reciprocating developing device in which a movable table is provided adjacent to the photosensitive member and movable in a tangential direction of the photosensitive member, and a plurality of developing devices are arranged on the movable table.

In the side-by-side developing device, a developer having a plurality of developers of different colors may be simply arranged in order around the photosensitive drum, and the structure seems to be simple. During the operation of the developing unit, it is necessary to deactivate the other remaining developing units.For this reason, the rotation of the magnetic brush roller in the developing unit is controlled, or the developing unit itself is moved from the surface of the photosensitive drum. Means for detachment and the like are required, and eventually, the side-by-side developing device also has a complicated structure and complicated operation control.

Further, according to this type of developing device, the diameter of the photosensitive drum is inevitably increased because a plurality of developing devices are sequentially arranged around the photosensitive drum, and therefore, the size of the electrophotographic copying machine can be reduced. Extremely difficult. Furthermore, despite the fact that the latent image formation position of each color on the photosensitive drum is constant,
The developing positions of the developing devices for the respective colors are different, and accordingly, the times until the latent images of the respective colors are developed are different, and it is necessary to correct the time decay of the latent images. Such a correction operation is not technically simple and complicates the control of the developing device and the copying machine as a whole.

On the other hand, a reciprocating type developing device is designed to perform development with only a developing device of a desired color facing a latent image on a photosensitive drum, so that the size of the photosensitive drum is reduced, and the color electrophotographic copying machine is further reduced. This has the advantage that it is possible to reduce the size of the image and to correct the time decay of the latent image of each color. However, when the concentration of the developer in each developing device decreases, it is necessary to automatically supply the toner into the developing device.

In a developing device based on the magnet brush method using a two-component developer composed of a conventional toner and a carrier that is a magnetic powder, in addition to the developing chamber containing the developer, the developer in the developing chamber has a predetermined concentration or less. In such a case, a toner chamber is provided for supplying toner to the developing chamber, and toner for replenishment is stored in the toner chamber.

"Problems to be Solved by the Invention" The larger the toner chamber, the larger the amount of toner for replenishment can be stored. However, the size of the developing device is naturally increased, and the entire developing device becomes huge. Large developing devices have high moments of inertia, and driving and controlling such devices at high speeds is extremely difficult and practically impossible.

Therefore, it is conceivable to adopt a method in which the toner chamber is usually made small and the toner chamber is replenished as needed through a cartridge type toner replenisher.

However, when a large number of copies are required, the developing device is frequently stopped or driven to the toner replenishing position, and the toner replenishing device is inserted into the developing device to replenish the toner in the toner chamber. You. Such an operation was not only extremely complicated for the operator but also caused a significant reduction in the copying speed.

The above description is also applied to a developing device configured to supply the developer.

There is also a type in which a toner discharge port of a hopper and a toner receiving port of a developing device are connected so that they can be constantly replenished by conveying means. However, in this method, since the developing device is moved at a high speed as described above, it is very difficult to increase the durability of the connecting portion by rapidly moving the conveying means.

Therefore, the main object of the present invention is to reduce the size of the developing device,
Accordingly, the present invention provides an image forming apparatus having a highly reliable toner replenishing device capable of miniaturizing the entire reciprocating type developing device, holding a large amount of toner, and continuously performing a large number of copies. It is to be.

Another object of the present invention is to provide an image forming apparatus provided with a toner replenishing device in which the inertia force of the reciprocating type developing device is reduced by reducing the size of the developing device and control is facilitated.

[Means for Solving the Problems] A first aspect of the present invention is directed to a plurality of developing devices for developing electrostatic images formed on an image carrier with toners of different colors, and a plurality of developing devices. Moving means for moving the selected one of the developing devices to a predetermined developing position of the image carrier; and a plurality of hoppers for supplying toners of colors corresponding to the plurality of developing devices, respectively. And a plurality of hoppers provided at a fixed position regardless of the movement of the developing device to the developing position, wherein a toner receiving port of the developing device and the developing device are provided for each of the plurality of developing devices. The toner discharge port of the hopper corresponding to the image forming apparatus is an image forming apparatus characterized in that the image forming apparatus communicates when the developing device is at the developing position.

A second invention of the present invention is the image forming apparatus according to the first invention, wherein the developing device develops the electrostatic image with a developer including a toner and a carrier.

Hereinafter, an embodiment of the present invention will be specifically described with reference to the drawings.

FIG. 1 is a longitudinal sectional view of a main part of an image forming apparatus for forming a full-color copy image embodying the present invention. In the figure, an electrostatic latent image carrier, that is, a photosensitive drum 1, which is a developing object, rotates in a direction indicated by an arrow in FIG.
An exposing device 3, a developing device 4, a transfer device 5, and a cleaning device 6 are arranged. The document reading device 7 is a document scanning unit
7A and a photoelectric element 7b having a color separation filter. The exposure unit 3 forms a color separation electrostatic latent image on the photosensitive drum 1 according to a signal of the photoelectric element 7b. The developing device 4 includes, for example, a yellow developing device 4Y using yellow toner, a magenta developing device 4M using magenta toner, a cyan developing device 4C using cyan toner, and a black developing device using black toner.
It has four 4BK developing units. When the moving table 100 moves in the direction of the arrow shown in the figure, each of the developing units 4Y, 4M, 4C, and 4BK is transferred to a developing position facing the photosensitive drum 1 to perform a developing operation.

On the other hand, the transfer device 5 is a dielectric drum 5b having a gripper 5a.
And a transfer discharger 5c inside thereof, and
The full-color image is the same as a conventional copier,
This is achieved by sequentially transferring color toners onto the transfer material supported above. The transfer material is supplied from a cassette 8 or a manual feed unit 9 through a paper feed path 8a or 9a. The transfer material having completed the transfer process is separated and conveyed by a separation unit 10 and is fixed on a fixing unit 11 and then is placed on a tray 12. Is stored.

Now, the developing device 4 will be described in more detail. A movable table 100 on which four developing units are mounted has a rack 101a, and a pinion fixed to the rack 101a on an output shaft of a motor M.
101b is engaged. By driving a motor (for example, a stepping motor) M, any desired one of the developing units 4Y, 4M, 4C, and 4BK can be transferred to the developing position.
Any one of the developing devices 4Y, 4M, 4C, and 4BK suitable for the developing position is pushed up in the direction of the photosensitive drum 1 by an elevating means (not shown) to be in a developable state. In the case of this figure, the developing position is below the photosensitive drum 1, and the yellow developing unit 4Y is in contact with the photosensitive drum 1. For example, in the case of forming a monochromatic or two-color image, the developing unit is passed through the developing position when it is separated from the photosensitive drum 1 without operating the lifting / lowering means of the unnecessary developing unit.

Next, the toner supply device according to the present invention will be described. In the present embodiment, as shown in FIG.
A toner replenishing device 200 is arranged on the near side in the figure. Yellow toner hopper 201Y and magenta toner hopper 201 that store the color toner to be supplied to each developing unit 4Y, 4M, 4C, 4BK
M, cyan toner hopper 201C, and black toner hopper 201BK are fixed to a support frame 202, and the support frame 202 is locked at a fixed position in the image forming apparatus main body. The support frame 202 having the rotation center 203 is rotatable around the rotation center 203 in the direction of the arrow a during maintenance and inspection of the developing devices 4Y, 4, M, 4C, 4BK and the hopper, and is kept at a position where it is easy to work. be able to.

In FIG. 2, the moving direction of the moving table 100 is the direction of arrow B.

FIG. 3 is a plan view showing the toner supply device and the developing device, and FIG. 4 is a front view of FIG. The toner replenishing device 200 is provided with a toner conveying means 300. Toner conveying means 3
00 is a toner supply pipe 300Y that can communicate with the yellow toner hopper 201Y, a toner supply pipe 300M that can communicate with the magenta toner hopper 201M, a toner supply pipe 300C that can communicate with the cyan toner hopper 201C, and a black toner, respectively. A toner supply pipe 300BK that can communicate with the hopper 201BK is provided, and each toner supply pipe 300Y, 300M, 300C, 300BK is provided with a conveying means such as a screw, and each toner supply pipe 300Y, 300M, 300C, 300BK.
The toner discharge ports 301Y, 301M, 301C, and 301BK provided at the respective outlets are open downward on a line d orthogonal to the moving direction c of the developing device 4. Line d passes near the developing position.
Each of the developing devices 4 is provided with a toner receiving port 400. When the developing device has the developing units 4Y, 4M, 4C, and 4BK, respectively, the toner outlet 301Y and the toner receiver 400Y, the toner outlet 301M and the toner receiver 400M, the toner outlet 301C and the toner receiver 40
0C, the toner outlet 301BK and the toner receiver 400BK match.

As described above, when any of the developing devices 4Y, 4M, 4C, and 4BK comes to the developing position, the developing device is pushed up in the direction of the photosensitive drum 1 by a lifting means (not shown) (the developing device 4Y in FIGS. 1 and 3). . As a result, one of the corresponding toner outlets 301 and toner receiver 4
One of 00 communicates.

According to the above-described embodiment, the toner outlets from the toner hoppers 201Y, 201M, 201C, and 201BK corresponding to any of the toner receivers 400Y, 400M, 400C, and 400BK of the moving developing devices 4Y, 4M, 4C, and 4BK.
Use of developing units 4Y, 4M, 4C, 4BK during development by configuring any of 301Y, 301M, 301C, 301BK so as to communicate at the developing position of developing units 4Y, 4M, 4C, 4BK Depending on the state, toner can always be supplied. For example, if a large amount of toner is replenished at once, the toner in the developing units 4Y, 4M, 4C, and 4BK will be insufficiently stirred with the carrier, and the toner will scatter from the developing units 4Y, 4M, 4C, and 4BK. Although the image may be stained, in this embodiment, since the toner supply position is the developing position, the developer concentration detectors of the developing devices 4Y, 4M, 4C, and 4BK need not be moved during the development. (Not shown), the toner can be gradually replenished, and a predetermined developing density and tribo can always be maintained. In addition, since there is no need for a transport means that always connects the toner receiving port 400 and the toner discharge port 301 of the developing units 4Y, 4M, 4C, and 4BK, the reliability can be kept high, and the transfer speed of the developing units 4Y, 4M, 4C, and 4BK can be maintained. It can also be applied to a high-speed color copying apparatus in which replenishment is performed quickly and frequently.

[Other Embodiments] FIG. 5 shows the hopper 201 having the same shape and the toner receiving ports 400 of the developing units 4Y, 4M, 4C, and 4BK arranged in the same direction as the moving direction of the developing units. In the state shown in FIG. 5, the developing unit 4Y is at the developing position, and the toner receiving port 400Y and the toner discharging port 301Y of the yellow toner hopper 201Y are in communication with each other so that toner can be supplied. When the developing device 4M comes to the developing position, the toner receiving port 400M of the developing device 4M coincides with the toner discharging port 301M of the magenta toner hopper 201M. When the developing device 4C comes to the developing position, the toner receiving port 400C of the developing device 4C.
When the developing unit 4BK comes to the developing position, the toner receiving port 400BK of the developing unit 4BK coincides with the toner discharging port 301BK of the black toner hopper 201BK.

In the embodiment, a hopper is provided corresponding to each of the developing devices so that the toner receiving port of the developing device at the developing position communicates with the toner outlet of the hopper corresponding to the developing device. It is also effective to provide hoppers corresponding to only a large number of developing devices, to adopt the same configuration, and to supply the remaining developing devices with toner cartridges.

〔The invention's effect〕

As described above, in the present invention, at least one developing unit is provided so as to be movable, a desired developing unit is transferred to a fixed developing position, and a developing device for developing a developing object is arranged at a fixed position. An image forming apparatus having at least one hopper, wherein at a developing position, a toner receiving port of a developing device at the developing position communicates with a toner outlet of a hopper corresponding to the developing device; Even in a small developing unit, large-capacity continuous image formation can be continued for a long period of time. Since the hopper and the developing unit are separated when the developing unit moves, the mechanism can be reliably used even when the developing unit moves at high speed. It is now possible to increase sex. This makes it possible to support high-speed color image forming apparatuses.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an entire configuration of an embodiment of the present invention, FIG. 2 is a perspective view of a hopper and a developing device of the embodiment of the present invention,
FIG. 3 is a plan view of a hopper and a developing device according to an embodiment of the present invention, FIG. 4 is a front view of FIG. 3, and FIG. 5 is a plan view of another embodiment. Reference numeral 4 denotes a developing device, 200 denotes a toner hopper, 300 denotes a toner supply pipe, 301 denotes a toner discharge port, and 400 denotes a toner receiving port.

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-61-188564 (JP, A) JP-A-62-116970 (JP, A) JP-A-61-97674 (JP, A) JP-A-62 27775 (JP, A) JP-A-2-64667 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G03G 13/01 G03G 15/01-15/01 117 G03G 13/08 G03G 13/095 G03G 15/08-15/08 507 G03G 15/095

Claims (2)

(57) [Claims] A plurality of developing devices for developing electrostatic images formed on the image carrier with toners of different colors, and a developing device selected from the plurality of developing devices. Moving means for moving to a predetermined developing position, and a plurality of hoppers for supplying toner of a color corresponding to each of the plurality of developing devices, regardless of the movement of the selected developing device to the developing position. A plurality of hoppers provided at fixed positions, wherein, for each of the plurality of developing units, a toner receiving port of the developing unit and a toner discharging port of the hopper corresponding to the developing unit are An image forming apparatus, which communicates when a developing device is at the developing position. 2. The apparatus according to claim 1, wherein said developing device develops said electrostatic image with a developer having toner and carrier.
An image forming apparatus according to claim 1.