JP2535652Y2 - Developing unit - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing unit detachable from an image forming apparatus such as an electrophotographic copying machine or a printer using electrophotographic technology. The present invention relates to a developing unit including a member that seals a communication port between a developing tank and a toner tank when used.

[0002]

2. Description of the Related Art Conventionally, a developing device is used as a developing device unit, and is detachably mountable to an image forming apparatus such as an electrophotographic copying machine having a shell structure capable of opening and closing an upper machine and a lower machine, and a printer using electrophotographic technology. In addition, there is known a system in which a new unit is replaced when a predetermined life time comes.

FIG. 5 shows a developer composed of a mixture of a magnetic carrier and a toner containing resin as a main component.
The two-component developing unit 50 is exemplified. In the figure,
A developer 52 is sealed in the developing tank 51, and a toner 54 is sealed in a toner tank 53 provided on the upper part of the developing tank 51. Further, a toner supply roll 5 is provided in a communication port 55 between the normal developing tank 51 and the toner tank 53.
6, which serves as a partition member between the developing tank 51 and the toner tank 53 and for supplying the toner 54 to the developing tank 51 in a timely manner. Further, a toner stirring member 57 having a toner conveying section 57 a is rotatably provided in the toner tank 53, and stirs the toner 54 and conveys the toner 54 to the toner supply roll 56.

When the toner density in the developer 52 decreases as the image is developed, a toner replenishment signal is output from an electric circuit (not shown) based on detection by a toner density sensor 58 provided in the developing tank 51, and a toner replenishment signal is output. Supply roll 56
Is rotated by a predetermined amount based on the signal, so that the toner 54 is supplied to the developing tank 51. As described above, the image quality is maintained by always controlling the toner concentration in the developer 52 to a certain range.

[0005]

As described above, the toner supply roll 5
Numeral 6 serves as a partition member between the developing tank 51 and the toner tank 53 to prevent the toner 54 from inadvertently entering the developer 52 in the developing tank 51. Since sponge is used as the material of the surface layer 56a, it is difficult to completely prevent the toner and the carrier from flowing out of the bubbles. In particular, when the new developing unit 50 is transported from the factory to the time it is delivered to the user after shipment, the new developing unit 50 is likely to flow out due to vibration.

The following items can be cited as problems due to outflow during transportation of toner and developer. The case where the developing unit 50 is placed in the normal state in the vertical direction (see FIG. 5).

In the drawing, it is conceivable that the toner 54 flows into the developer 52 as indicated by an arrow A. In this state, when the image forming apparatus is mounted and started to be used, the toner concentration in the developer 52 is high (over toner).
There are adverse effects such as occurrence of background stain on a white background portion of the paper, non-reproduction of halftone, and the like, and insufficient stirring of the toner 54, resulting in a decrease in toner charge amount and toner scattering. Occurs.

The case where the developing unit 50 is placed in an overturned state (see FIG. 6). In the figure, as indicated by arrow B,
It is conceivable that the developer 52 flows into the toner 54. In this state, when the apparatus is mounted on the image forming apparatus and started to be used, the amount of the developer 52 in the developing tank 51 decreases, the toner density sensor 58 does not operate, and the toner density control (toner replenishment) is not performed. Consumption of toner due to development lowers the toner concentration in the developer 52 (under toner), and causes problems such as a decrease in image density.

[0009]

SUMMARY OF THE INVENTION In view of the above problems, the present invention moves developer and toner between a developing tank and a toner tank when a new developing unit is not used until it is mounted on the main body of the image forming apparatus and is operated. It is therefore an object of the present invention to provide a developing unit capable of reliably preventing the occurrence of an image and stabilizing the image quality.

[0010]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a developing tank containing a two-component developer and a toner stirring member rotatably containing a toner through a communication port with the developing tank. A developing device unit having a communicating toner tank and a toner supply roller rotatably provided in the communication port so as to close the communication port, and one end of the developing device unit detachable from the main body of the image forming apparatus; while being fixed, the other end is the toner supply is interposed between the circumferential surface and the inner wall of the toner tank of the toner supplying roll before the unused time is running is attached to the main body of the image forming apparatus
A flexible thin plate member that covers the peripheral surface of the roll, seals the communication port, and is wound up with the rotation of the toner stirring member after operation to release the sealing of the communication port. Features.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 4 is a schematic configuration side view showing the entire image forming apparatus to which the developing unit according to the embodiment of the present invention is attached.

The image forming apparatus P is disposed above and in close proximity to the photosensitive drum 21, a charger 22 for uniformly charging the photosensitive drum 21, and an electrostatic latent image on the photosensitive drum 21. A developing unit 1 according to one embodiment of the present invention, in which a print head 23 for forming an image and a developing unit for developing the electrostatic latent image formed on the photosensitive drum 21 with toner are integrated, A transfer unit 24 for transferring recording information onto a sheet of paper, a cleaner unit 25 for removing residual toner on the photosensitive drum 21 that has not been transferred in the transfer process by the transfer unit 24, and a waste unit provided below the cleaner unit 25 A toner container 26 and the like are provided.

The image forming apparatus P includes a paper feed cassette 27 containing sheets of a predetermined size in a stacked state, and a paper feed roller 28 for taking out and feeding the sheets one by one from the top.
And a guide plate 29 for guiding the sheet feeding direction, a standby roll 30 for transporting the sheet to the transfer position in synchronization with recording information formed on the photosensitive drum 21, and the like.

Further, the image forming apparatus P includes a guide plate 31 for receiving and guiding the sheet, a fixing device 32 for fixing the recording information after the transfer by heating and pressure, and a sheet discharge for discharging the sheet onto a discharge tray 34. A roll 33 and the like are provided.

The image forming apparatus P includes a lower body DB that houses the lower part of the transfer unit 24 and the fixing unit 32, and an upper body UB that is provided to be rotatable about the hinge 35 with respect to the lower body DB. The developing unit 1 according to one embodiment of the present invention is detachably mounted at a predetermined position in the main body of the image forming apparatus P in a so-called shell open state in which the upper body UB is opened, and then the upper body UB is opened. It is used in a state where the UB is closed, that is, in a so-called shell closed state, and an image is formed on a sheet.

FIG. 1 is a side sectional view showing the structure of a main part of a developing unit 1 (two-component developer system) according to an embodiment of the present invention. The developing unit 1 includes a developing case 2, a toner replenishing roll 3 provided therein, a toner stirring member 4 having a longer blade 4 a, a toner concentration sensor 5, and a thin plate member 6. I have.

In the developing device case 2, an upper toner tank 2b for storing the toner 2a and a lower developing tank 2d for storing the developer 2c are formed, and the toner 2a is stored in the lowermost part of the toner tank 2b. A communication port 2e between the toner tank 2b and the developing tank 2d for supplying the toner into the toner tank 2c is provided.

The toner supply roll 3 is rotatably provided in contact with the inner walls 2g and 2h of the toner tank 2b near the communication port 2e, and replenishes the toner 2a to the lower developing tank 2d. It is formed of a material such as a sponge. Further, on the side of the toner supply roll 3, the peripheral surface of the toner supply roll 3, the inner wall 2h of the toner tank 2b, and the toner tank 2
and a toner reservoir 2k formed by a protrusion 2j extending inward of b.

The toner stirring member 4 is rotatably provided at a position of the toner tank 2b below the toner replenishing roll 3, and stirs the toner 2a to make the toner 2a uniform and sends the toner 2a to the toner replenishing roll 3.

The toner density sensor 5 is provided in the developing tank 2d, detects the toner density in the developer 2c, and outputs a toner replenishment signal via an electric circuit (not shown) when the toner density is lowered. 3, the toner 2a is supplied to the developing tank 2d, and the concentration in the developer 2c is controlled within a certain range.

The thin plate member 6 has one end (end 6a side) near the communication port 2e when the developing unit 1 is not used until it is delivered to the user after shipment from the factory, mounted on the main body of the image forming apparatus, and operated. Between the inner walls 2g and 2h of the toner layer 2b and the peripheral surface of the toner replenishing roll 3 and the communication port 2e.
A sealing member for sealing the entire area, and the other end side (end 6b side)
Is fixedly connected to a long blade 4a formed on the toner stirring member 4 by a double-sided pressure-sensitive adhesive tape, an adhesive or the like at a joint portion 7. Further, the thin plate member 6 is made of a material such as a PET film and has flexibility, and a portion from the tip of the joining portion 7 to contact with the peripheral surface of the toner supply roll 3 is an opening 6c. This prevents the toner 2a from accumulating and stopping the movement in the toner tank 2b.

The operation of the above configuration will be described. In the assembly process at the factory, as shown in FIG. 1, a thin plate member 6 is interposed between the peripheral surface of the surface layer 3a of the toner supply roll 3 of the developing unit 1 and the inner walls 2g and 2h near the communication port 2e. Then, it is shipped so as to be wrapped around at one end (end 6a side), and the entire communication port 2e is sealed. Therefore, the developing unit 1
The thin plate member 6 does not cause the flow of the toner 2a and the flow of the developer 2c from the communication port 2e even if the sheet member 6 is vibrated during transportation or the like, even if it is turned over.

After the developing unit 1 is delivered to the user after shipment from the factory, mounted on the image forming apparatus main body and operated, the toner in the developer 2c is consumed as the development is performed.
When the toner concentration sensor 5 detects a decrease in toner concentration and outputs a toner supply signal, the toner supply roller 3 is rotated by a predetermined amount by an electric circuit (not shown), and the toner 2a is supplied into the developing tank 2d.

In response to the output of the supply signal, the toner supply roll 3 and the toner stirring member 4 are rotated in the directions of arrows C and D by a drive system (not shown). Here, the thin plate member 6
The thin plate member 6 is forcibly wound up by the toner stirring member 4 in the direction of arrow G because the toner stirring member 4 and the toner stirring member 4 are fixedly connected at the joining portion 7 (see FIG. 2). afterwards,
When the toner replenishment signal is continuously output by the toner density sensor 5, the thin plate member 6 is completely separated from the toner replenishing roll 3, wraps around the toner stirring member 4 (see FIG. 3), and the communication port of the thin plate member 6 is formed. The sealing of 2e is released.

As shown in FIG. 3, the flexible thin plate member 6 acts repulsively to expand outward and gently winds around the toner stirring member 4, and the toner supply roll 3 of the thin plate member 6 The end 6a at one end, which is interposed between the inner wall 2g and the inner wall 2h of the toner tank 2b, is connected to the bottom of the toner tank 2b as the toner stirring member 4 is rotated to stir and transport the toner 2a. It rotates while stroking the 2s and the bottom 2s. By this operation, the toner 2a in the toner tank 2b (in FIG. 3, the toner amount is shown to be small for the sake of explanation) is conveyed in the direction of the toner replenishing roll 3 as indicated by arrow H, and the toner 2a is replenished by toner as indicated by arrow F. Roll 3
The toner drops upward and temporarily accumulates in the toner reservoir 2k and is clogged in the air bubbles in the surface layer 3a. The toner replenishing roll 3 is rotated by a toner replenishment signal from the toner density sensor 5.
With the timely rotation of the toner, the toner 2a clogged in the bubble portion is squeezed at the tips of the inner walls 2g and 2h of the toner tank 2b near the communication port 2e, and the developer 2c from the communication port 2e as shown by the arrow E.
Fall inside. As described above, when the flexible thin plate member 6 is not used, such as when the new developing unit 1 is transported,
It functions as a sealing member between the developing tank 2d and the toner tank 2b and, after being mounted on the image forming apparatus main body and operating, functions as a toner stirring member 4 for stirring and transporting the toner 2a.

Since the present embodiment is configured as described above, the outflow and inflow of the toner 2a and the developer 2c from the communication port 2e due to vibrations during transportation of the new developing unit 1 after shipment are prevented. As a result, since the amount of the developer 2c sealed is kept constant, the toner density control always operates normally, and the image quality is stabilized. Further, since the thin plate member 6 also has a role as a toner stirring member 4 in addition to a role as a sealing member for sealing the communication port 2e, a part for conveying the toner at the bottom 2s of the toner tank 2b is provided. It can be omitted and the number of parts can be reduced.

[0027]

According to the present invention, as described in detail above, after a new developing unit is shipped from a factory, it is delivered to a user, mounted on the main body of the image forming apparatus, and operated when not in use. In addition, it is possible to reliably prevent the developer and the toner from moving between the developing tank and the toner tank. Therefore, it is possible to avoid the occurrence of defective toner density in the developer, and it is possible to eliminate the background soiling, toner scattering, and the like, leading to stabilization of the image density and stable supply of good image quality.

[Brief description of the drawings]

FIG. 1 is a side sectional view of a main part showing a state in which a thin plate member seals a communication port when a developing unit according to an embodiment of the present invention is transported after being shipped from a factory.

FIG. 2 is a side sectional view of a main part showing a state in which the sealing of a thin plate member is released after the developing unit of FIG. 1 is mounted on a main body of the image forming apparatus.

FIG. 3 is a side cross-sectional view of a main part showing a state after the sealing of the thin plate member is released after the developing unit of FIG. 1 is mounted on the main body of the image forming apparatus.

FIG. 4 is a schematic cross-sectional view illustrating the entire image forming apparatus to which the developing unit of FIG. 1 is mounted.

FIG. 5 is a side sectional view of a conventional developing unit.

FIG. 6 is a side sectional view showing a state in which the developing unit of FIG. 5 is turned over.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Developing unit 2a Toner 2b Toner tank 2c Developer 2d Developing tank 2e Communication port 2g, 2h Inner wall of toner tank near communication port 3 Toner supply roll 4 Toner stirring member 6 Thin plate member

Claims (1)

(57) [Scope of request for utility model registration] A developing tank containing a two-component developer, a toner tank containing toner and rotatably enclosing a toner stirring member and communicating with the developing tank via a communication port; A developing device unit having a toner supply roller rotatably provided so as to close the communication port and detachably attached to the main body of the image forming apparatus, wherein one end is fixed to the toner stirring member, and the other end is the image forming member. It is interposed between the circumferential surface and the inner wall of the toner tank in front of the toner supply roll when not in use to be operated is attached to the body of the device circumference of the toner supply roll
A flexible thin plate member that covers the surface and seals the communication port, and after being operated, is wound up with the rotation of the toner stirring member and releases the sealing of the communication port. Developing unit.