JPH09211950A - Developing device for electrophotographic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a developing device for an electrophotographic device capable of suppressing a deterioration in the image quality of a recorded image caused by the fact that fresh toner and stale toner remaining on a toner supplying roller are mixed when the fresh toner is supplied into a toner hopper. SOLUTION: This developing device is provided with a toner hopper 1 having a toner feeding port 3 and a toner housing part 2 housing the toner fed from the toner charge port, a developing roller 6 for holding the toner and carrying it to a photoreceptor, a supplying roller 7 for holding the toner housed in the toner housing part of the toner hopper and supplying the toner to the developing roller and a toner regulating member 8 for regulating the thickness of the layer of the toner held on the developing roller. Then, the bottom wall 2a of the toner housing part of the toner hopper is placed in a lower position not reaching the bottom end of a circle of the outer periphery of the supplying roller.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a developing device for an electrophotographic apparatus.

[0002]

2. Description of the Related Art An electrophotographic apparatus used in a recording section of a facsimile apparatus charges a surface of a photoconductor with a charging device, then forms an electrostatic latent image on the surface of the photoconductor with an exposure device, and then a developing device. The electrostatic latent image on the surface of the photoconductor is developed to form a toner image. Further, the transfer device transfers the toner image on the photoconductor onto a recording sheet for recording.

As a developing device provided in this electrophotographic apparatus, there is one which adopts a non-magnetic one-component developing system. This developing device uses a non-magnetic one-component toner, and has a toner hopper having a toner inlet and a toner accommodating portion for accommodating the toner introduced from the toner inlet, and a developing device that holds the toner and conveys it to the photosensitive member. A roller, a supply roller that holds the toner stored in the toner storage portion of the toner hopper and supplies the toner to the developing roller, and a toner regulating member that regulates the layer thickness of the toner held by the developing roller. There is.

In this developing device, the following operation is performed. Non-magnetic one-component toner is charged from the toner charging port of the toner hopper and stored in the toner storage portion. The toner accommodated in the toner accommodating portion is pressed against the outer peripheral surface (front surface) of the toner supplying roller by gravity, or is conveyed to the toner supplying roller by driving an agitator provided in the toner accommodating portion. The toner supply roller and the developing roller are in contact with each other and rotate in the toner conveying direction. The rotating toner supply roller holds the toner and conveys it to the contact portion between the toner supply roller and the developing roller. Here, the toner is triboelectrically charged as a backup.

Next, the toner adheres to the outer peripheral surface (front surface) of the developing roller due to the difference between the potential of the toner supply roller and the potential of the developing roller, and moves to the regulating member by the rotation of the developing roller. When the toner passes through the tip of the regulation member, the toner is pressed by the regulation member and the layer thickness is regulated to become a thin layer. At the same time, the toner is frictionally charged by being brought into sliding contact with the rotating developing roller while being pressed by the regulating member. Further, the toner is conveyed to the contact portion between the developing roller and the photosensitive drum and transferred to the photosensitive drum, and the electrostatic latent image formed on the photosensitive drum is developed to form a toner image.

By the way, in the conventional developing apparatus of this type, both rollers are horizontally arranged in parallel so that the toner supply roller is located lower than the developing roller, and the bottom wall of the toner accommodating portion of the toner hopper is the toner. It was formed so as to extend beyond the lower end of the outer peripheral surface of the supply roller and to be positioned higher than this lower end.

[0007]

In the developing device adopting the conventional non-magnetic one-component developing system as described above, the bottom wall of the toner accommodating portion of the toner hopper is located higher than the lowest position of the outer peripheral surface of the toner supply roller. It is said that. That is, the bottom of the toner storage portion of the toner hopper is shallow. However, with this configuration, the toner stored in the toner storage portion of the toner hopper is used up, and the amount of toner is reduced. When new toner is supplied from the toner input port to the toner storage portion and is replenished, it is input to the toner storage portion. The new toner may mix with the old toner remaining on the upper surface of the outer peripheral surface of the toner supply roller.

That is, when new toner is introduced into the toner accommodating portion from the toner inlet, the toner is accommodated in a mountain shape on the bottom wall of the toner accommodating portion. Here, if the bottom of the toner storage portion is shallow, there will be more of the new toner piles stored in the toner storage portion at a position higher than the upper end of the outer peripheral surface of the toner supply roller, and the new toner above the piles The toner may move toward the outer peripheral surface of the toner supply roller and mix with the old toner remaining on the upper surface of the outer peripheral surface of the toner supply roller.

When new toner and old toner are mixed, the charge of the toner may have a polarity opposite to the polarity of the regular charge, or the charge may become weak. For this reason, there is a problem that the fogging phenomenon occurs in which toner adheres to the non-charged portion of the photoconductor drum and the image quality of the recorded image deteriorates.

The present invention has been made in view of the above circumstances, and suppresses deterioration of image quality of a recorded image due to mixing of new toner with old toner remaining on the toner supply roller when the toner hopper is replenished with new toner. An object of the present invention is to provide a developing device for an electrophotographic apparatus.

[0011]

According to another aspect of the present invention, there is provided a developing device for an electrophotographic apparatus, a toner hopper having a toner inlet and a toner accommodating portion for accommodating the toner introduced from the toner inlet, and holding the toner. And conveys the toner to the photoconductor, and supplies the toner stored in the toner storage portion of the toner hopper to the developing roller, and regulates the layer thickness of the toner held by the developing roller. A toner regulating member is provided, and the bottom wall of the toner accommodating portion of the toner hopper is located at a low position that does not reach the lower end of the outer peripheral circle of the supply roller.

According to the structure of the present invention, the toner accommodating portion of the toner hopper is configured such that the bottom wall is located at a lower position so as not to reach the lower end of the outer peripheral circle of the supply roller and the bottom is deep. Therefore, when the new toner is replenished in the toner storage unit of the toner hopper, the peak of the new toner loaded and stored in the toner storage unit is lowered and the toner is supplied in the toner pile stored in the toner storage unit. It is possible to increase the number of portions at a position lower than the height of the upper end of the outer peripheral surface of the roller. For example, the crest of new toner can be lower than the upper end of the outer peripheral surface of the toner supply roller. As a result, the toner on the top of the pile of new toner that has been thrown into the toner storage unit and stored
It is possible to prevent the toner from moving toward the outer peripheral surface of the toner supply roller and mixing with old toner remaining on the outer peripheral surface of the toner supply roller.

For this reason, the new toner and the old toner are mixed with each other, the toner charging becomes reverse polarity, or the charging becomes weak, and as a result, a fogging phenomenon occurs in which the toner adheres to the non-charged portion of the photosensitive drum. It is possible to prevent a situation in which the quality of a recorded image is deteriorated.

According to a second aspect of the present invention, in the developing device of the electrophotographic apparatus according to the first aspect, the toner hopper is provided in the toner hopper so as to cover the developing roller and the supply roller from below, adjacent to the toner accommodating portion. Is formed, and a boundary wall is formed at a boundary between the toner receiving portion and the toner containing portion so as to prevent the toner contained in the toner containing portion from moving toward the toner receiving portion. It is characterized by being.

According to the structure of the present invention, the toner spilled from the developing roller and the supplying roller can be received by the toner receiving portion and used to supply the toner to the developing roller again. Further, the boundary wall formed at the boundary between the toner receiving portion and the toner containing portion prevents the toner contained in the toner containing portion from being dammed and prevented from moving to the toner receiving portion side, that is, the supply roller side,
The toner can be stably stored in the toner storage portion.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a non-magnetic one-component developing system. The toner hopper 1 is horizontally long and is arranged along a direction perpendicular to the direction in which a recording sheet (not shown) is conveyed. The toner hopper 1 has a toner storage portion 2 for storing toner. The toner storage portion 2 has a depth capable of storing the toner T with a margin, as will be described later, and the upper surface portion is opened as a toner inlet 3. ing. A side of the toner hopper 1 facing the photoconductor drum 12 is opened as a roller placement portion 4, and a bottom wall of the roller placement portion 4 is formed as a toner receiving wall 9.

Further, the toner accommodating portion 2 of the toner hopper 1 is provided with a stirrer 5, and the stirrer 5 is rotated by a rotation driving device (not shown). A developing roller 6 is disposed in parallel with the toner accommodating portion 2 in the roller arrangement portion 4 of the toner hopper 1, and a toner supply roller having a diameter smaller than that of the developing roller 6 is provided at a position closer to the toner accommodating portion than the developing roller 6. 7 is arranged in parallel with the developing roller 6. The toner supply roller 7 is in contact with the developing roller 6 and is in contact with the developing roller 6.
It is located in the lower position. The developing roller 6 and the toner supply roller 7 are rotated by a rotation drive mechanism (not shown), and a bias voltage is applied by a bias power source.

A regulating member 8 is provided on the roller arrangement portion 4 above the developing roller 6, and the tip of the regulating member 8 faces the outer peripheral surface of the developing roller 6 with a very small gap. doing.

The toner hopper 1 will be further described. The bottom wall of the roller arrangement portion 4 of the toner hopper 1 is formed as a toner receiving portion 9 that covers the lower side of the developing roller 6 and the toner supply roller 7. The toner receiving portion 9 receives the toner T leaked from the contact portion between the developing roller 6 and the toner supply roller 7. The lower end of the bottom wall 2 a of the toner containing portion 2 is located at a low position so that it cannot reach the toner receiving portion 9.

The toner containing portion 2 has a volume capable of containing the amount of toner T to be replenished at one time of toner replenishment. The size and shape are set so that the toner T can be accommodated in a state where there are few portions higher than the upper end Hc. In other words, the toner T is accommodated in the toner accommodating portion 2 so that the toner T can be accommodated in a large portion of the mountain of the toner T accommodated in the toner accommodating portion 2 at a position lower than the upper end Hc of the outer peripheral surface of the toner supply roller 7. The size and shape are set.

That is, it is possible to lower the peak of the new toner T which is charged into the toner container 2 and accommodated in a raised state. For example, the peak of the new toner T can be made lower than the upper end Hc of the outer peripheral surface of the toner supply roller 7.

Therefore, the bottom wall 2a of the toner container 2 is located at a low position Ha which does not reach the lower end Hb of the outer peripheral surface of the toner supply roller 7. Specifically, the bottom wall 2a of the toner container 2 is located at a low position that does not reach the toner receiving wall 5. As a result, the bottom portion of the toner storage portion 2 is deepened, and the portion for storing the amount of toner T to be replenished at one time of toner replenishment is positioned lower than the conventional portion.

As a result, the upper end H of the outer peripheral surface of the toner supply roller 7 among the piles of the toner T stored in the toner storage portion 2.
It is possible to increase the number of parts at a position lower than the height of c. For example, the bottom wall 2a of the toner storage unit 2 is set so that the crest of the toner T stored in the toner storage unit 2 is at the same height as the central axis of the toner supply roller 7.

The bottom wall 2a of the toner accommodating portion 2 has a toner receiving portion side wall and the toner receiving portion 9 has a toner accommodating portion side wall, and these boundary portions are combined to form a boundary wall 10. Is formed. This boundary wall 1
The position of the upper end of 0 is located, for example, between the central axis of the toner supply roller 7 and the upper end Hc of the outer peripheral surface of the toner supply roller 7.

The plate 11 is provided in the toner receiving portion 9 and prevents the toner T from leaking to the outside by coming into contact with the developing roller 6. A photosensitive drum 12 is provided outside the developing roller 6 in parallel with the developing roller 6, and the photosensitive drum 12 is in contact with the developing roller 6.

In the developing device thus constructed, the following operation is performed. When performing the developing operation,
The non-magnetic one-component toner T is charged from the toner charging port 3 of the toner hopper 1 and stored in the toner storage portion 2. The toner T stored in the toner storage unit 2 is pressed against the outer peripheral surface (front surface) of the toner supply roller 7 by gravity, or is conveyed to the toner supply roller 7 by rotation of the agitator 5 provided in the toner storage unit 2. . In this case, the boundary wall 10 has the toner T
Are prevented from moving from the toner containing portion 2 to the toner receiving portion 9 side, that is, the toner supply roller 7 side.

The rotation driving mechanism rotates the developing roller 6 and the toner supply roller 7 in the directions of the arrows in the figure. The rotating toner supply roller 7 holds the toner T and conveys it to the contact portion between the toner supply roller 7 and the developing roller 6. Toner T
At the contact portion between the toner supplying roller 7 and the developing roller 6, the toner supplying roller 7 and the developing roller 6 are frictionally charged as a preliminary charging by the sliding contact.

Part of the toner T spills from the contact portion between the toner supply roller 7 and the developing roller 6, but this is received by the toner receiving portion 9 of the toner hopper 1, and further adheres to the outer peripheral surface of the toner supply roller 7. The toner supply roller 7 and the developing roller 6 are rotated again by the rotation of the toner supply roller 7.
Transport it to the contact area with. In this case, the boundary wall 10 prevents the toner T from moving from the toner receiving portion 9 to the toner containing portion 2.

Next, the toner T adheres to the outer peripheral surface of the developing roller 6 due to the difference between the potential of the toner supply roller 7 and the potential of the developing roller 6, and is conveyed to the regulating member 8 by the rotation of the developing roller 6. When the toner T passes through the tip of the regulating member 8, the toner T is pressed by the regulating member 8 and its layer thickness is regulated to become a thin layer. At the same time, the toner T is pressed by the regulating member 8 and comes into sliding contact with the rotating developing roller 6 to be frictionally charged. Further, the toner T is conveyed to the contact portion between the developing roller and the photoconductor drum 12 and transferred to the photoconductor drum 12, and the electrostatic latent image formed on the photoconductor drum 12 is developed to form a toner image. .

By the way, the toner contained in the toner accommodating portion 2 of the toner hopper 1 is used up, and the amount of the toner is reduced, so that a new toner T is introduced into the toner accommodating portion 2 from the toner inlet 3 to be replenished. When new toner T is introduced into the toner container 2 from the toner inlet 3, the toner T is contained in the form of a mountain on the bottom wall of the toner container 2.

Here, the toner storage portion 2 of the toner hopper 1
Has a configuration in which the bottom wall 2a is located at a low position so as not to reach the lower end Hb of the outer peripheral circle of the supply roller 7 and the bottom is deep. Therefore, when new toner T is supplied to the toner storage unit 2,
New toner T that has been loaded and stored in the toner storage unit 2
It is possible to lower the height of the peak of the toner and to increase the portion of the toner T accommodated in the toner accommodating portion 2 at a position lower than the height of the upper end of the outer peripheral surface of the toner supply roller 9. For example,
The peak of the new toner T can be made lower than the upper end of the outer peripheral surface of the toner supply roller 9. As a result, the toner T on the top of the pile of new toner that has been loaded and stored in the toner storage unit 2 moves toward the outer peripheral surface of the toner supply roller 2 and remains on the outer peripheral surface of the toner supply roller 2. Mixing with the toner T can be suppressed.

Therefore, the new toner T and the old toner T are
When the toner is charged with the opposite polarity or becomes weaker, the result is that the toner adheres to the non-charged portion of the photoconductor drum, causing a fogging phenomenon, which deteriorates the quality of the recorded image. Can be prevented.

The old toner remaining on the outer peripheral surface (front surface) of the toner supply roller 7 is supplied to the developing roller 6 side, and then the agitator 5 is rotated to replace the new toner T stored in the toner storage portion 2 with the toner. Carry to supply roller 7.

FIG. 2 shows the relationship between the depth of the bottom wall 2a of the toner accommodating portion 2 in the developing device and the degree of fogging in the image. According to this diagram, when the bottom wall 2a of the toner accommodating portion 2 of the toner hopper 1 is at the same position (0 mm) as the lower end of the outer circumferential circle of the toner supply roller 7, the toner fogging amount in the image is large. Recognize. On the other hand, when the bottom wall 2a of the toner accommodating portion 2 of the toner hopper 1 is at a lower position 10 mm and 20 mm away from the lower end of the outer circumference of the toner supply roller 7, the toner fog amount in the image is very small. I understand.

Toner fogging in an image is practically 10
If the allowable range is less than%, the toner storage unit 2
The bottom wall 2a of the toner supply roller 7 is 1 from the lower end of the outer circumference circle.
It can be said that it is preferable that the positions are 0 mm to 20 mm apart.

The invention of the present application is not limited to the above-described embodiments, but can be modified in various ways.

[0037]

As described above, according to the developing device of the electrophotographic apparatus of the first aspect of the invention, the toner accommodating portion of the toner hopper is positioned so that the bottom wall is too low to reach the lower end of the outer peripheral circle of the supply roller. It has a deep bottom. For this reason,
When the new toner is replenished in the toner storage portion of the toner hopper, the peak of the new toner loaded and stored in the toner storage portion is lowered so that the outer periphery of the toner supply roller is in the toner pile stored in the toner storage portion. More parts can be located below the height of the top of the surface. As a result, the toner in the upper part of the pile of new toner that has been loaded and stored in the toner storage unit moves toward the outer peripheral surface of the toner supply roller and mixes with the old toner remaining on the outer peripheral surface of the toner supply roller. Can be suppressed.

For this reason, the new toner and the old toner are mixed with each other, the toner charging becomes opposite in polarity, or the charging becomes weak. As a result, a fogging phenomenon occurs in which the toner adheres to the non-charged portion of the photosensitive drum. It is possible to prevent a situation in which the quality of a recorded image is deteriorated.

According to the second aspect of the present invention, the toner spilled from the developing roller and the supply roller can be received by the toner receiving section and used again to supply the toner to the developing roller, and the toner receiving section can be used. The boundary wall formed at the boundary between the toner storage portion and the toner storage portion prevents the toner stored in the toner storage portion from being blocked, and the toner receiving portion side,
That is, the toner can be stably stored in the toner storage portion by preventing the toner from moving to the supply roller side.

[Brief description of drawings]

FIG. 1 is a sectional view showing a developing device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing the relationship between the depth of the bottom of the toner storage unit in the developing device and the fogging phenomenon in an image.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Toner hopper, 2 ... Toner storage part, 2a ... Bottom wall, 3 ... Toner input port, 4 ... Roller arrangement part, 5 ... Stirrer, 6 ... Developing roller, 7 ... Toner supply roller, 8 ... Regulating member, 9 ... Toner receiving portion, 10 ... Boundary wall.

Claims (2)

[Claims] 1. A toner hopper having a toner input port and a toner storage part for storing the toner input from the toner input port, a developing roller for holding the toner and transporting the toner to a photosensitive member, and a toner storage part of the toner hopper. A toner supply member for holding the contained toner and supplying it to the developing roller; and a toner regulating member for regulating the layer thickness of the toner held on the developing roller, and the bottom wall of the toner accommodating portion of the toner hopper is A developing device for an electrophotographic apparatus, which is located at a low position which does not reach a lower end of an outer peripheral circle of the supply roller. 2. A toner receiving portion that covers the developing roller and the supply roller from below is formed in the toner hopper adjacent to the toner storing portion, and a boundary portion between the toner receiving portion and the toner storing portion is formed. 2. The electrophotographic apparatus developing device according to claim 1, wherein a boundary wall is formed on the surface of the toner storage unit to prevent the toner stored in the toner storage unit from moving toward the toner receiving unit. apparatus.