JP3734092B2 - Image forming apparatus - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a developing device using an electrophotographic system, and more particularly to a developing device used for an image forming apparatus such as a printer, a facsimile machine, and a copying machine using a dry developer.
[0002]
[Prior art]
There are the following techniques related to a developing device for developing an electrostatic latent image.
(1). A two-component developing device comprising toner storage means and a replenishing device provided integrally with the developing means, and utilizing the gravity of the toner in transferring toner from the toner storing means attached above the developing means to the developing means (Refer to Japanese Patent Laid-Open No. 63-301071).
(2). A toner storing means provided separately from the developing means, and a toner supply pipe having a toner transfer screw disposed therein between the toner storing means and the developing means, are attached above the developing device. A technology relating to a two-component developing device that uses a screw and the gravity of toner in transferring toner from the toner storage means to the developing means (refer to Japanese Patent Publication Nos. 64-8330 and 4-78876).
(3). A technique relating to a two-component developing device that has a developer agitating means inside a photosensitive drum, is connected to a developing device by a pipe, and circulates the developer (see Japanese Patent Publication No. 5-21082).
(4). The developer or carrier is supplied to the developer container, and at the same time, the same amount of developer is discharged. The toner consumed by the development is detected by the volume detection means, and the toner is supplied to determine the developer concentration in the developer container. A technique for easily keeping constant at all times (see Japanese Patent Publication No. 60-18065).
(5). A developing unit; a unit for supplying a predetermined amount of carrier to the developing unit according to a predetermined development time or a predetermined copying amount; a detecting unit for detecting a change in the ratio between the carrier and the toner in the developer; A technique relating to a developing device having means for supplying toner to the developing section by means of the above and means for discharging a predetermined amount or more of developer in the developing section (see Japanese Patent Application Laid-Open No. 51-13249).
(6). A technique for extending the life of a developer by supplying an additional developer including a toner and a carrier to the developer in the developing device (see Japanese Patent Laid-Open No. 4-353881).
[0003]
[Problems to be solved by the invention]
In a conventional developing device, a developing portion for storing developer to supply developer to a developing sleeve provided opposite to a photosensitive member as an electrostatic latent image carrier and a tank for supplying toner are provided in the developing sleeve. In the vicinity, the developing unit configured as a unit containing the developing sleeve is integrated with the developing unit, so that this component becomes large, the apparatus configuration becomes complicated, and the operability during maintenance of the apparatus decreases. There was a problem of doing.
[0004]
SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a developing device capable of downsizing a developing unit configured in a unit shape so as to face an electrostatic latent image, simplifying the configuration, and improving operability during maintenance. .
[0005]
[Means for Solving the Problems]
According to the first aspect of the present invention, there is provided a latent image carrier on which an electrostatic latent image is formed, a developing unit for visualizing the electrostatic latent image, and the electrostatic latent image supplied to the developing unit. In the image forming apparatus having a toner storage unit that stores toner of powder used for visualizing an image inside the apparatus main body , the toner storage unit and the developing unit are separate, and A screw having the toner supply pipe connecting the toner storing means and the developing means, a rotor formed in a screw shape, and a stator formed of an elastic body such as a rubber material so as to enclose the roller. It consists pump unit, a toner transferring means for transferring the toner in the toner storing means is connected to the supply pipe to the developing unit, an air to the toner between the developing unit and the toner reservoir means And a air supply means for supplying said developing unit performs a toner supply opening, a reduced pressure of the developing unit inside provided separately located from said toner supply opening for receiving the toner to be transferred from said toner transferring means It has an air vent and an air filter that covers the air vent, and the amount of air supplied by the air supply means is 0.5 to 2 liters / minute .
[0011]
[Action]
According to the present invention, the toner storage unit, the toner supply unit, and the toner transfer unit are arranged at arbitrary positions apart from the development unit, and the toner transfer unit mixes toner and air from the toner supply unit to the development unit. Transfer qi.
[0012]
【Example】
FIG. 1 is a schematic sectional side view of a developing device and a latent image carrier employing one embodiment of the present invention, and FIG. 2 is a perspective view of the developing means shown in FIG.
[0013]
In FIG. 1, reference numeral 1 denotes a photosensitive drum as a latent image carrier. The photosensitive drum 1 is rotatably supported on a side plate (not shown), and is driven to rotate clockwise in the drawing by a driving unit. The length of the photosensitive drum 1 in the width direction is set to correspond to the maximum width of the transfer sheet that can be used by the image forming apparatus including the photosensitive drum 1. On the photosensitive drum 1, charging and exposure are performed by a known electrophotographic image forming process to form an electrostatic latent image. This electrostatic latent image is visualized by a developer provided by a developing device that employs a magnetic brush developing method in a well-known dry two-component developing method. The photosensitive drum 1 may be configured in a belt shape in addition to the drum shape.
[0014]
The developing device mainly includes a developing unit 2, a toner storage unit 3, a toner supply unit 4, a toner transfer unit 5, and the like.
[0015]
The developing unit 2 includes a developing sleeve 6 that supplies developer to the photosensitive drum 1, developer stirring members 8 and 9, a developer layer regulating member 10, a stirring and conveying unit 11, a case 12 that accommodates and holds them, and the like. Toner replenishing means 7. The developing means 2 is an exposure position around the photosensitive drum 1 where the electrostatic image is formed on the photosensitive drum 1 by irradiating the light image P, and the electrostatic latent image is visualized. A developing sleeve 6 is disposed in a state of facing the photosensitive drum 1 in FIG. 1 between a transfer position where a transfer charger Q for transferring a toner image to a transfer sheet is arranged. Further, the developing means 2 is provided with an air vent hole 7d as a pressure reducing means in the toner replenishing means 7 so that the pressure inside the developing means 2 is reduced to allow the developer to pass through the gap between the developing sleeve 6 and the case 12. It is configured not to scatter outside.
[0016]
The developing sleeve 6 has a known configuration including a sleeve made of a non-magnetic material and a magnet disposed inside the sleeve, and is driven to rotate counterclockwise by driving means. The length in the width direction of the developing sleeve 6 is set to be substantially the same as the length in the width direction of the photosensitive drum 1.
[0017]
The toner replenishing means 7 has a well-known configuration having a screw 7a for toner conveyance and a paddle 7b for toner discharge having a groove in the busbar direction on the peripheral surface, and the toner supplied by the toner transfer means 5 is shown in the figure. Based on the signal from the toner detecting means that does not, the toner is uniformly supplied into the developing means 2. As shown in FIG. 2, the toner supply member 7 includes a toner supply port 14 that receives toner transferred from the toner transfer unit 5 at a position protruding from the side plate 13 of the developing unit 2. The toner taken from the toner supply port 14 is supplied to one end of the screw 7a. The toner replenishing means 7 has an air vent hole 7d formed above the paddle 7b of the upper plate 7c, and an air filter 15 is fitted in the air vent hole 7d.
[0018]
The developer agitating members 8 and 9 have a well-known configuration including a paddle that agitates the toner and the carrier inside the developing means 2 and sends them to the developing sleeve.
The developer layer regulating member 10 regulates the height of the developer spike formed on the developing sleeve 6. Excess developer scraped off by the developer layer regulating member 10 is conveyed to the upper part of the agitating and conveying member 11 as indicated by an arrow in FIG.
The agitating and conveying member 11 distributes and conveys the developer conveyed by the screw 11a and the fin 11b to the developer agitating members 8 and 9, respectively.
[0019]
FIG. 3 is a side sectional view showing the toner storage means 3, the toner supply means 4, and the toner transfer means 5 of the present invention.
[0020]
The toner storage means 3 includes a storage means body 16 formed in a substantially funnel shape having an opening 3a at the top and an opening 3b at the bottom, and an openable / closable lid 17 provided to close the opening 3a. Yes. The toner 18 is appropriately supplied from the opening 3a to the inside of the storage unit main body 16.
[0021]
A toner supply unit 4 is arranged in connection with the toner storage unit 3. The toner supply unit 4 mainly includes a supply unit main body 19, a motor 20, a screw 21 and the like.
[0022]
The supply means body 19 which is a toner storage container is formed in a cylindrical shape at the bottom and a funnel shape at the top, and is connected to the storage means body 16 so as to be connected to the opening 3b at the upper right. The toner 18 supplied to the storage means main body 16 from the opening 3a flows down into the supply means 19 from the opening 3b by its own weight.
[0023]
A motor attachment member 22 that supports the motor 20 is attached to the upper left of the supply means body 19. A screw 21 is attached to the output shaft of the motor 20 via a sleeve 23. The screw 21 penetrates the supply means main body 19 from the upper part to the lower part, and the lower end thereof extends to substantially the same position as the lower end part of the supply means main body 19. The toner 18 in the supply means 19 is conveyed downward while being agitated by the screw 21.
[0024]
A toner transfer means 5 is connected to the lower end of the toner supply means 4. The toner transfer means 5 is a powder pump unit, and is constituted by a screw pump (commonly known as a MONO pump, conventionally known).
The toner transfer means 5 is mainly composed of a rotor 24 formed in a screw shape, a stator 25, an upper pump holder 26, a lower pump holder 27, an air supply means 28, and the like.
[0025]
The rotor 24 is connected to the motor 20 via the screw 21. Around the rotor 24, a stator 25 formed of an elastic body such as a rubber material is provided so as to wrap the rotor 24. A passage for feeding the toner 18 while the rotor 24 rotates is formed in the stator 25. Has been. The stateer 25 is held by an upper pump holder 26 and a lower pump holder 27.
[0026]
The upper pump holder 26 is formed in a cylindrical shape, and connects the toner transfer means 5 and the toner supply means 4, and a connection portion between the toner transfer means 5 and the toner supply means 4 and the outside are connected to the side of the upper pump holder 26. An air supply port 29 that communicates is formed. The lower pump holder 27 is formed in a stepped cylinder shape, and a stator 25 is fitted in the upper portion with a gap, and a toner passage 30 for discharging the toner 18 conveyed by the rotor 24 is formed in the lower portion. Yes. An air supply port 31 that communicates the outside with the toner passage 30 is formed at the side of the lower pump holder 27.
[0027]
A fan 28 as an air supply means disposed above the motor 20 is driven by the motor 20 and sucks outside air from an air intake port 28a provided at an upper portion, and air discharge ports 28b and 28c provided at side portions. More air is discharged. The air discharge ports 28b and 28c communicate with the air supply ports 29 and 31 through pipes, respectively, and the toner 18 entering the toner transfer means 5 by the rotation of the fan 28 enters the toner transfer means 5 from the air supply port 28 and the toner transfer means. 5 is supplied with air of about 0.5 to 2 liters / minute from the air supply port 31. By this air flow, fluidization of the toner 18 is promoted, and the toner transfer unit 5 reliably transfers the toner 18. The toner 18 discharged from the toner transfer means 5 is sent to the toner supply means 7 through the supply pipe 32. The amount of air supplied by the fan 28 is very small. After contributing to the transfer of the toner 18, the air is discharged to the outside through the air vent hole 7 d through the air filter 15. By discharging the air from the air vent hole 7d to the outside, there is an effect of stabilizing toner transfer and toner replenishment and preventing toner scattering from the developing means 2. In this embodiment, the fan 28 is arranged coaxially with the motor 20. However, the fan 28 may be arranged at any other location using driving means in addition to the motor 20.
[0028]
The screw pump known as the MONO pump used in the present embodiment is a rotary displacement type and pressure-type transfer, and is transferred at a high solid-gas ratio by extremely small air. The interior is filled and continuously transferred. Therefore, it is possible to control the flow rate with high quantification and high-precision flow rate for continuous transfer, and the transfer air to be used is very small to promote fluidization of the powder and maintain a uniform flow state over the entire length of the transfer line. The amount of air is sufficient. Furthermore, since it is low-speed and high-concentration transfer, there is no powder crushing, small-diameter piping is required, there is no trouble with wear of the transfer pipe, noise is low, the structure is simple, economy, reliability, It has features such as excellent maintainability.
[0029]
In the present embodiment, the toner storage unit 3, the toner supply unit 4, and the toner transfer unit 5 are united separately from the developing unit 2 and are simply connected by a supply pipe 32. Since there are few restrictions and the degree of freedom in layout increases, it is possible to secure an economical toner storage capacity, improve the workability of toner supply, and improve workability such as assembly and adjustment.
[0030]
In the toner storage unit 3, the detachable toner cartridge system conventionally used in place of the storage unit main body 16 can be used to further improve the toner replenishment workability. In this case, since the shape of the toner cartridge does not depend on the developing unit 2, the workability of toner replenishment is improved, and standardization with other models is facilitated, and the cost can be reduced.
Further, the toner storage unit 3 may be separated from the toner supply unit 4 and the toner transfer unit 5 and may be arranged at different positions to transfer only the toner 18 to the toner supply unit 4.
[0031]
FIG. 4 is a side sectional view for explaining another embodiment of the present invention. The same reference numerals are given to the same parts as those in the above embodiment, and detailed explanations thereof are omitted.
This embodiment differs from the above embodiment in that a storage means body 33 is provided in place of the storage means body 16, a supply means body 34 is provided in place of the supply means body 19, and the toner supply means 4, toner transfer means 5, The only difference is that the is placed horizontally.
[0032]
The storage means main body 33 is formed in a funnel shape, and has an opening 33a at the top and an opening 33b at the bottom. An openable / closable lid 35 is provided on the upper portion of the storage means main body 33 so as to close the opening 33a. Below the storage means main body 33, a supply means main body 34 connected to the opening 33b and formed in a cylindrical shape is arranged. With the configuration shown in FIG. 4, the storage means 33 can be formed larger than the configuration shown in FIG.
Also in this embodiment, the storage means main body 33 may be separated from the supply means main body 34 and may be arranged at a different position to transfer only the toner 18 to the supply means main body 34.
[0033]
In each of the above-described embodiments, an example in which the two-component development method is adopted has been described. However, a one-component development method may be adopted.
[0034]
【The invention's effect】
According to the present invention, the toner storage unit, the toner supply unit, and the toner transfer unit are disposed at arbitrary positions apart from the developing unit, and the toner transfer unit mixes the toner and the air from the toner supply unit to the developing unit. Since the air is transferred, there are few restrictions on the installation location, and the degree of freedom in layout is increased. Therefore, the developing means configured in a unit shape facing the electrostatic latent image is downsized, and the configuration is easy and economical. It is possible to secure a sufficient toner storage capacity, improve the workability of toner replenishment, and improve workability such as assembly and adjustment.
Further, according to the present invention, since the toner replenishing means has an air vent hole as a pressure reducing means, it is possible to stabilize toner transfer, stabilize toner replenishment, and prevent toner scattering from the developing means. .
[Brief description of the drawings]
FIG. 1 is a schematic side view of a latent image carrier and a developing device adopting an embodiment of the present invention.
FIG. 2 is a perspective view of developing means for explaining an embodiment of the present invention.
FIG. 3 is a schematic cross-sectional side view of a toner storage unit, a toner supply unit, and a toner transfer unit for explaining an embodiment of the present invention.
FIG. 4 is a schematic sectional side view of a toner storage unit, a toner supply unit, and a toner transfer unit for explaining another embodiment of the present invention.
[Explanation of symbols]
1 Electrostatic latent image carrier (photosensitive drum)
2 Developing means 3 Toner storage means 4 Toner supply means 5 Toner transfer means 7 Toner replenishing means 7d Air vent 24 Rotor 25 Stator 28 Air supply means

Claims (1)

A latent image carrier for forming an electrostatic latent image on the surface ; developing means for visualizing the electrostatic latent image; and developing the electrostatic latent image supplied to the developing means In an image forming apparatus provided with toner storage means for storing toner of powder to be used inside the apparatus main body ,
The toner storing means and the developing means are separate bodies;
The toner supply pipe connecting the toner storage means and the developing means;
A screw pump unit having a rotor formed in a screw shape and a stator formed of an elastic body such as a rubber material so as to enclose the rotor, and connected to the supply pipe and connected to the toner storage unit. Toner transfer means for transferring toner to the developing means ;
Air supply means for supplying air to the toner between the toner storage means and the development means ,
The developing unit includes a toner supply port that receives toner transferred from the toner transfer unit, an air vent hole that is provided at a position different from the toner supply port, and that decompresses the developing unit, and an air filter that covers the air vent hole And
The image forming apparatus according to claim 1, wherein the air supply amount of the air supply means is 0.5 to 2 liters / minute .

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