JP4547196B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an electrophotographic image forming apparatus.

  Conventionally, since the toner container is made of a hard bottle such as a cartridge or a bottle, there has been a big problem in the disposal of the used container accompanying the replacement of the toner container. In other words, the used toner storage container is collected from the user by the manufacturer, and is recycled, reused, and incinerated. However, the container has a large capacity and requires a high distribution cost until it is recovered.

  In addition, a toner storage container whose volume can be reduced has been proposed in the past, but when replenishing from the container using a toner replenishing device, the replenishment performance cannot be stably maintained, Even when a container capable of reducing the volume only during transportation is used, problems such as toner contamination occur when the toner is transferred, and it has not been put into practical use.

  Further, since the conventional toner transfer technology is based on the mechanical auger means, the toner replenishing device and the toner storage container have to be installed at a position integrated with or very close to the developing device. This complicates the configuration of the toner replenishing device, hinders high costs, low productivity, and machine maintenance, makes it difficult to protect and maintain the toner quality characteristics, and further improves the operability of the user's toner container replacement work. There was also difficulty.

  Note that a toner replenishing device is known by the applicant of the present application in which air is jetted into a toner storage container, the toner is fluidized and discharged from the container, and the discharged toner is replenished to the developing device using an air flow or a powder pump. There is no suggestion.

  This toner replenishing device has various advantages such that the installation position of the toner container can be set regardless of the position of the developing device, a soft case can be used for the container, and unnecessary stress is not applied to the toner. Is.

  However, the above-described toner replenishing device also has some problems. For example, since the insertion / removal member inserted / removed into / from the container is provided with a toner passage and an air supply passage, the toner passage will be too narrow unless it has a certain diameter. For this reason, when the diameter of the insertion / extraction member is increased, toner leakage from the seal valve occurs when the insertion / extraction member is extracted.

  An object of the present invention is to provide an image forming apparatus in which a toner passage having an appropriate size can be obtained without increasing the diameter of the insertion / extraction member.

In order to achieve the above object, the present invention provides an image forming apparatus that replenishes toner accommodated in a plurality of toner storage containers to a plurality of developing devices via a plurality of toner replenishing devices. An insertion / removal member formed in a tubular shape to be inserted / removed from / from, a single air supply means for supplying air into the toner storage container through the insertion / removal member, and a toner stored in the toner storage container to replenish the developing device A suction-type powder pump, and a dual-purpose passage that serves both as an air passage through which the air supplied into the toner storage container passes and a toner passage through which the toner discharged from the toner storage container passes. provided, and toner aspiration direction and the feed direction of the air of the powder pump is turned backward in該兼passage, et from the air supply means of the sole Both over passage is connected to the combined passage is branched into a plurality of air valves are provided for selecting the air supply to each air passage is branched, air from the air supply means of said alone or two at the same time The image forming apparatus is characterized in that the air valve is controlled so as not to be supplied to the toner container.

The present invention is effective when air supply from the air supply means to the toner storage container is performed when the cumulative time of toner replenishment time due to the operation of the powder pump exceeds a predetermined time. .

Further, the present invention is effective when the air supply unit and the toner replenishment unit are provided on the insertion / extraction member, and the air supply unit is located above the toner supply unit .

  Furthermore, the present invention is effective when the air supply portion and the toner replenishment portion are provided on the insertion / extraction member, and the toner replenishment portion is located above the air supply portion.

Furthermore, the present invention is effective when the diameter of the air supply unit from the air supply unit is smaller than the diameter of the toner supply unit.
Furthermore, the present invention is effective when the air supply from the air supply means to the toner storage container is supplied from the lowest position of the toner supply path.

According to the present invention , the insertion / removal member can have a single tube structure, and the manufacturing cost of the member can be greatly reduced. Moreover, even with a single air pump, the required amount of air can be reliably supplied to each toner storage container.
According to the second aspect of the present invention, it is possible to supply toner by air pressure even if a single tube structure insertion / extraction member is provided.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a schematic view showing a color laser printer which is an example of an image forming apparatus according to the present invention. This color laser printer has a configuration in which a paper feed unit 2 is disposed at the bottom of the apparatus main body 1 and an image forming unit 3 is disposed above the paper feed unit 2. The image forming unit 3 is provided with a transfer belt device arranged so as to be inclined so that the paper feed side is on the bottom and the paper discharge side is on the top. The transfer belt device 8 has an endless transfer belt 8a wound around a plurality of belt wheels, in this example, four belt wheels, and magenta (M) in order from the bottom to the upper running side of the transfer belt 8a. , Four image forming units 4M, 4C, 4Y, and 4Bk for cyan (C), yellow (Y), and black (Bk) are arranged in parallel.

  FIG. 2 is an explanatory diagram showing an enlarged portion of the image forming unit 4. As shown in FIGS. 1 and 2, each of the image forming units 4M, 4C, 4Y, and 4Bk is a photosensitive member as an image carrier. A photosensitive drum 5 is provided, and the photosensitive drum 5 is rotationally driven clockwise by a driving means (not shown). Around the photosensitive drum 5, a charging roll 6 as a charging unit, an optical writing unit in which writing by a laser beam is performed by an optical writing unit 7, a developing unit 10 as a developing unit, and a cleaning unit 9 as a cleaning unit are provided. Yes. The developing device 10 is a two-component developing device composed of toner and carrier, and toner corresponding to the amount of consumed toner is supplied from the toner storage container 20 by the toner supply device. The toner replenishing device replenishes each image forming unit 4M, 4C, 4Y, 4Bk with toner stored in the same number of toner storage containers 20.

  As shown in FIG. 3, the developing device 10 is provided with a uniaxial eccentric screw pump that is a suction type powder pump 11 in the vicinity or integrally therewith. As shown in FIG. 4, the powder pump 11 is composed of a rotor 12 made of a screw shape eccentrically made of a rigid material such as metal and an elastic body such as rubber, and has a double screw shape. And a holder 14 made of a resin material or the like that wraps them and forms a powder conveyance path. The rotor 12 is rotationally driven through a gear 16 integrally connected to a drive shaft 15 connected by a pin joint. Reference numeral 17 denotes an electromagnetic clutch, and the operation of the powder pump 11 is controlled by the clutch.

  Further, a toner suction portion 18 is provided at the tip of the holder 14, that is, the right end in FIG. 3, and a toner connection port 45 and a toner transfer tube provided in a toner suction portion 18 and a nozzle 40 as an insertion / removal member described later. 19 is connected. As the toner transfer tube 19, for example, a flexible tube having a diameter of 4 to 10 mm and made of a rubber material having excellent toner resistance (for example, polyurethane, nitrile, EPDM, silicon, etc.) is extremely used. An effective and flexible tube can be easily piped up and down, left and right. In the toner replenishing device configured as described above, the single-shaft eccentric screw pump that is the powder pump 11 is capable of continuous quantitative transfer at a high solid-gas ratio, and an accurate toner proportional to the rotational speed of the rotor 12. It is known that the transfer amount can be obtained. Therefore, when a toner replenishment command is issued by image density detection or the like, the powder pump 11 is operated, and the requested amount of toner is replenished to the developing device 10.

  On the other hand, the setting unit 50 provided in the image forming apparatus main body 1 in which the toner storage container 20 is set is configured as a separate unit from the developing device 10. The set unit 50 is provided with a nozzle 40 having a circular cross section that is inserted into and removed from the toner storage container 20, and the toner storage container 20 is set to the set unit 50 of the image forming apparatus main body 1 from above. The nozzle 40 provided in the set unit 50 is provided with a pointed member 44 formed in a conical shape in the upper part by integral molding or fixing, and also serves as an air supply path and a toner supply path following the pointed member 44. A passage 41 is provided. The inside of the nozzle 40 has a single tube structure, and the passage 41 is bent at the lower end of the nozzle 40 to the left in the figure, and a toner connection port 42 to which the toner transfer tube 19 is connected is provided at the tip. Yes. Further, the passage 41 is provided with an air connection port 43 that is bent to the right in the drawing above the toner connection port 42.

  In the case of this embodiment, the air connection port 43 is connected to an air pump 30 as an air supply means via an air transfer pipe 31. When the air pump 30 is activated, air is ejected from the pump into the toner storage container 20 through the air transfer pipe 31 and the passage 41. Then, the air blown into the toner storage container 20 flows through the toner layer while diffusing the toner.

  The toner storage container 20 is configured as a back-in-box type having a deformable toner bag 21 for storing toner and an outer box 22 for storing the toner bag 21 and having a rigidity higher than that of the bag. . The toner bag 21 is made of, for example, a flexible sheet made of resin or paper such as polyethylene or nylon having a thickness of about 80 μm to a toner container 20 μm, and the toner bag 21 has a blow molding method. A base part 23 made of resin or the like provided with a toner supply part is fixed. The toner bag 21 has a hermetically sealed structure, and a sealing valve 24 made of an elastic material, preferably foamed sponge, is provided as a self-closing valve at the base 23 of the bottom. In addition, it is effective as a countermeasure against static electricity or moisture prevention to perform aluminum vapor deposition on the front or back surface of the sheet of the toner bag 21.

  In the toner replenishing device configured as described above, a passage 41 serving as both an air supply path and a toner replenishing path is provided in the nozzle 40 which is inserted into and removed from the image forming apparatus main body 1 by attaching / detaching the toner storage container 20 to / from the image forming apparatus body 1. ing. Therefore, compared with the case where the air supply path and the toner supply path are provided separately, the structure is simple, the manufacturing cost is greatly reduced, and the cross-sectional area of the path 41 itself can be increased, so that toner clogging hardly occurs. Become. Furthermore, in the present embodiment, since the air connection port 43 is provided above the toner connection port 42 in the nozzle 40, leakage of toner to the air connection port can be reduced.

  By the way, when the nozzle 40 has a single tube structure, it is not possible to move toner and supply air at the same time. Therefore, control is performed so that toner movement and air supply are not performed simultaneously, and a preferred control example will be described with reference to FIG.

  In FIG. 4, the toner replenishment amount is determined by determining the ON time of the powder pump 11 based on the T sensor output for each print. When the determined toner supply is completed, the on-time of the powder pump 11 is integrated. When the integrated time reaches a predetermined time, the air pump 30 is operated after the toner supply that has reached the predetermined time is completed, and the toner is supplied. Air is supplied into the storage container 20. The amount of air supplied is a fixed amount, and the integration time is reset.

By controlling toner replenishment in this way, stable toner replenishment performance can always be ensured even if the nozzle 40 has a single tube structure.
Further, when air is supplied to the toner storage container 20 by the air pump 30, if the nozzle 40 has a single tube structure, there is a possibility that the air may be sent to the developing device 10 through the toner transfer tube 19 and the powder pump 11. However, since the powder pump 11 is a uniaxial eccentric screw pump, the toner transfer path is a sealed path, and such a problem does not occur. Furthermore, when toner is sent by air pressure without using a powder pump, an open / close valve (not shown) may be provided in the toner transfer path instead of the powder pump. In this case, when an air valve is also provided in the air passage of the air pump 30 and air is supplied to the toner storage container 20, the air valve is opened after closing the on-off valve, and the internal pressure of the toner storage container is increased to some extent. If the on-off valve is opened after closing the valve, the toner can be replenished without the toner due to the air pressure being sent to the air pump side.

  In such control, the operation time of the air pump 30 is shorter than the operation time of the powder pump 11. Therefore, when four image forming units 4 are provided as in the present embodiment, it is not necessary to provide the air pump 30 for each toner replenishing device, and only one air pump 30 is possible. In this case, the air pump 30 control examples are shown in FIGS.

FIG. 5 is a diagram illustrating the relationship between the air pump 30 and the toner storage containers 20M, 20C, 20Y, and 20Bk. The air supply tube 31 from the air pump 30 includes four toner storage containers 20M, 20C, and 20Y. , 20Bk so that air can be supplied to the four tubes 32M, 32C, 32Y, 32Bk. Each of the branched tubes 32M, 32C, 32Y, 32Bk is provided with air valves 33M, 33C, 33Y, 33Bk, and the toner storage container 20M connected to the turned-on air valves 33M, 33C, 33Y, 33Bk. , 20C, 20Y, 20Bk is supplied with air only.

As shown in FIG. 6, the control of such a configuration is such that the air pump 30 is turned on for a time corresponding to the total amount of air supplied to each, and when the air pump 30 is on, the amount of air supplied is adjusted. In response, each air valve 33M, 33C, 33Y, 33Bk is opened. At this time, by controlling not to turn on the two or more air valves 33M, 33C, 33Y, and 33Bk at the same time, a necessary amount of air can be supplied to each of the toner storage containers 20M, 20C, 20Y, and 20Bk.

  The toner replenishing device configured as described above can reduce the cost compared to the case where a plurality of air pumps are provided. In addition, since air is not supplied to the two or more toner storage containers 20M, 20C, 20Y, and 20Bk at the same time, the necessary amount of air can be supplied to each container with high accuracy. Further, in this control, the nozzle 40 functions sufficiently with a single tube structure by not performing toner replenishment and air supply at the same time.

FIG. 7 is an explanatory cross-sectional view showing another embodiment of the present invention. In this embodiment, the toner connection port 42 is provided above the air connection port 43 in the nozzle 40.
With this configuration, the toner clogging in the nozzle 40 can be prevented by the air flow. Further, by making the diameter of the air connection port 43 smaller than that of the toner connection port 42, it is possible to prevent toner from leaking into the toner at the air connection port 43.

FIG. 7 is an explanatory cross-sectional view showing another embodiment of the present invention. In this embodiment, the toner connection port 42 is provided above the air connection port 43 in the nozzle 40.
With this configuration, the toner clogging in the nozzle 40 can be prevented by the air flow. Further, by making the diameter of the air connection port 43 smaller than that of the toner connection port 42, it is possible to prevent toner from leaking into the toner at the air connection port 43.

  FIG. 8 is an explanatory sectional view showing still another embodiment of the present invention. In this embodiment, the lowest position from the nozzle 40 to the powder pump 11, in this example, a branch pipe in the middle of the toner transfer tube 19. 34 is provided, and the tube 31 of the air pump 30 is connected to the branch pipe 34.

  With this configuration, since the air from the air pump 30 is supplied from the lowest position in the toner transfer path, it is possible to reliably prevent the path from being clogged with toner accumulated by its own weight at the lowest position.

As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to the said embodiment, Various modifications can be made.
For example, the cross-sectional shape of the nozzle is preferably circular as in the above-described embodiment, but it is not necessary to limit to a circular shape, and may be polygonal, elliptical, or track-shaped. Further, the configuration of the developing device to which toner is replenished may be arbitrary, and can be applied to a device using a one-component developer.

1 is a schematic diagram illustrating an overall configuration of a color image forming apparatus of the present invention. FIG. 2 is an explanatory view showing an enlarged image forming unit in the color image forming apparatus of FIG. 1. FIG. 3 is a cross-sectional explanatory view showing an embodiment of a toner supply device of the present invention. It is a timing chart which shows the example of control of a powder pump and an air pump. It is explanatory drawing of the air supply path which shows other embodiment of this invention. It is a timing chart which shows the example of control of FIG. It is sectional drawing of the nozzle which shows other embodiment of this invention. FIG. 10 is a cross-sectional explanatory view of a toner supply device showing still another embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Developing device 11 Powder pump 20 Toner storage container 30 Air pump 40 Nozzle 41 Passage

Claims (6)

In an image forming apparatus for supplying toner stored in a plurality of toner storage containers to a plurality of developing devices via a plurality of toner supply devices,
An insertion / removal member formed in a tubular shape that is inserted into / removed from the bottom of the toner storage container,
A single air supply means for supplying air into the toner storage container through the insertion / extraction member;
A suction type powder pump for replenishing the toner stored in the toner storage container to the developing device;
A dual-purpose passage serving as an air passage through which the air supplied into the toner storage container passes and a toner passage through which the toner discharged from the toner storage container passes is provided in the insertion / extraction member;
In the dual-purpose passage, the toner suction direction of the powder pump and the air supply direction are opposite to each other,
The air passage from the single air supply means is branched into a plurality of branches and connected to the dual-purpose passage, and an air valve for selecting air supply is provided in each branched air passage,
Image forming apparatus characterized by air from the air supply means of said alone to control two or more said air valve so as not to be supplied to the toner container at the same time. 2. The image forming apparatus according to claim 1 , wherein air supply from the air supply means to the toner storage container is performed when a cumulative time of toner replenishment time due to the operation of the powder pump exceeds a predetermined time. An image forming apparatus. 2. The image forming apparatus according to claim 1 , wherein an air supply unit and the toner supply unit are provided on the insertion / extraction member, and the air supply unit is located above the toner supply unit. 2. The image forming apparatus according to claim 1 , wherein an air supply unit and the toner supply unit are provided on the insertion / extraction member, and the toner supply unit is located above the air supply unit. 5. The image forming apparatus according to claim 1 , wherein the diameter of the air supply unit from the air supply unit is smaller than the diameter of the toner supply unit. 5. The image forming apparatus according to claim 4 , wherein the air supply from the air supply means to the toner container is supplied from the lowest position of the toner supply path.

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