JPH04107586A - Development device - Google Patents

Abstract

PURPOSE:To securely move developer from a roller to another roller and to make the amount of the developer which is conveyed to a development place constant. CONSTITUTION:The position relation between magnetic poles N12 and N13, and magnetic poles S21 and S22 which face each other at a place where a developing roller 10 and a conveyor roller 20 and close to each other is so set that a rectangle formed by connecting points (a) - (d) is a parallelogram and angles alphaacute anglebad and acute angledcb are <=85 deg., where (a) and (b) are the center facing parts of the magnetic poles N12 and N13 on the outer periphery of a sleeve 12 and (c) and (d) are the center facing parts of the magnetic poles S21 and S22 on the outer periphery of a sleeve 22. Consequently, the arrangement of the magnetic poles at the facing parts of the both is adjusted to such relation that the developer is smoothly passed and received and never enters the part between the rollers, thereby making the amount of the developer constant.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a developing device such as a copying machine or a printer that uses a powder developer.

[Prior Art] Conventionally, the developing device includes a developing roller in which a cylindrical sleeve rotates around a fixed magnet, and a conveyance roller in which a cylindrical sleeve rotates around a fixed magnet similarly to the developing roller. a regulating member facing the conveyance roller; and a supply section that supplies developer to the conveyance roller, and the developer supplied from the supply section to the conveyance roller is received by the developing roller via the conveyance roller. Then, the developer held on the developing roller is brought into contact with the photoreceptor and static! It has been proposed to develop an image and then send the developer after the development back to the supply section via a conveyance roller.

5. Problems to be Solved by the Invention: However, the above-mentioned developing device has various problems in that the developer is not properly transferred between the developing roller and the conveyance roller.

In other words, due to a failure in the supply of developer from the conveyance roller to the development roller, sufficient developer cannot be sent to the development area, resulting in a decrease in image density or image defects, or the developer that should be sent back from the development roller to the conveyance roller. The developer slips between the two rollers and is conveyed to the development site again, resulting in an excess of developer, resulting in inconveniences such as poor image density and uneven background.

[Invention or problem to be solved]

Therefore, the present invention has been made to solve the above problems, and includes a first fixed magnet (11) and a first fixed magnet (11).
II), a first sleeve (12) that rotates around (in the direction of arrow The second fixed magnet (21) is surrounded by the first sleeve (1).
2) and a second sleeve (22) that rotates in the same direction (arrow X2 direction), and is disposed opposite to the first roller (10);
The first fixed magnet body ( 11
), the first sleeve (
12) A magnetic pole (N, □) and B magnetic pole (Na3) of the same polarity are provided adjacently along the rotation direction (arrow X1 direction),
At the portion of the second fixed magnet body (21) facing the first roller (10), there is an arrow X in the rotational direction of the second sleeve (22);
Along the force direction, the A and B magnetic poles (N 12.N
, '-) and the C magnetic pole (S, , ) and D magnetic pole (S
, ) are provided adjacent to each other, and the A and B magnetic poles (N +2+
Points a, b, and C above on the outer periphery of the first sleeve opposite to N13), respectively.

If the points on the outer periphery of the second sleeve facing the D magnetic poles (S , , S , , ) are respectively c and d, then these points ad
, c, b form a quadrilateral or parallelogram drawn by connecting them,
The A magnetic pole (N1t) and the B magnetic pole (N1
s) C magnetic poles (S, , ) and D magnetic poles (S , , ) are arranged.

Embodiment Next, an embodiment of the developing device having the above structure will be described.

In FIG. 1, a housing 1 of a developing device S has empty chambers 2, 3, and 4.5 formed from the photoreceptor 100 side.

A wall 6 will be installed between vacant rooms 4 and 5, and these vacant rooms 4.5
are communicated only via passages 7, 8 at both ends. One end of the empty chamber 5 (on the right side in FIG. 2) is extended to form a toner supply path 9.
or is formed.

Said vacant room 2. 3. 4. 5, a developing roller 10. Conveyance roller 20. Supply vane 30. Stirring blades 40 are provided, and the toner supply path 9 connects to the toner supply device 5.
Connected to 0.

The developing roller 10 is composed of a magnet 11 and a sleeve 12 surrounding the magnet. The sleeve 12 is designed to rotate in the direction of arrow X1.

The magnet body 11 is fixed in a non-rotating state, and has a plurality of magnetic poles Nll2S11. N IlI N +3.
S 12 are each extended in the axial direction, and conveyor rollers 20
Magnetic poles N12. of the same polarity are placed opposite to each other. N, 3 or adjacent.

Like the developing roller 10, the conveying roller 20 is composed of a magnet 21 and a sleeve 22, and a regulating plate 23 faces the upper part of the sleeve 22.

The sleeve 22 is arranged in the same direction as the sleeve 12 (arrow x2
direction). The magnet body 21 is fixed in a non-rotating state, and has a plurality of magnetic poles S 2 on its outer periphery.
1 S 22+ N 21, S 23. S 24+N
Magnetic poles S11 . 3. A magnetic pole S of the same polarity is adjacent to S2t and is located at a portion facing the supply vane 30; S and 4 are adjacent. Therefore, in the opposing portion of the developing roller 10 and the conveyance roller 20, magnetic poles N Ij and S of different polarities are formed.
, 1+ NI2 and Stt are facing each other.

Magnetic poles N l, which face each other in the vicinity of the developing roller 10 and the conveying roller 20! + N + 3, magnetic pole S 21+
As shown in FIG. 3, the positional relationship of S 2t is on the outer circumference of the sleeve 12 and on the magnetic pole N l 2+ N l
, are respectively "a" and "b", respectively, on the outer periphery of the sleeve 22 and the magnetic pole S! If the center opposing parts of l+ 322 are respectively °゛C"d, then the angles that form a quadrilateral or parallelogram drawn by connecting these four points a, b, c, and d and are /bad and /dcb α or 8
The angle should be less than 5 degrees.

In the developing device S having the above structure, a powder developer containing toner and xenoa is accommodated in the empty chambers 4 and 5.

The developer in the empty chamber 5 is mixed and agitated by the rotation of the stirring blade 40 and is conveyed from the right side to the left side in FIG.

The developer in the chamber 4 is conveyed from the left side to the right side in FIG. 2 while being mixed and agitated by the rotation of the supply blade 30, and is sent back to the chamber 5 via the passage 7. Further, the developer transported through the empty chamber 4 is supplied to a transport roller 20 .

The developer supplied to the conveyance roller 20 is held on the outer circumference of the sleeve 22 by the magnetic force of the magnet body 21, and is conveyed in the direction of arrow
After being regulated by 3, the receiver is held by the Fii field formed between the magnetic pole S21 and the magnetic pole \13 of the lever opposite to the magnetic pole S21, and is transferred to the developing roller IO.

The developer held on the developing roller 10 is held on the outer circumference of the sleeve 12 by the magnetic force of the magnet 11, and is conveyed in the direction of arrow x1 as the sleeve 12 rotates, and is transferred to the photoreceptor 1.
After developing the electrostatic latent image formed on the outer periphery of the magnetic pole N1 in the area facing the magnetic pole NIF,
．． and the magnetic pole S22,
It is sent back to the conveyance roller 20.

The developer sent back to the conveyance roller 20 is conveyed in the direction of arrow X and the force direction as the sleeve 22 rotates, and the developer is conveyed to the magnetic poles S23 and 3.
It falls off from the sleeve 22 at the intermediate opposing portion of the tube 24 and is sent back into the cavity 4.

Here, the development side receiver from the conveyance roller 20 to the development roller 10 is located in the direction of the arrow x2 with respect to the normal line from the magnetic pole i<13 or the magnetic pole St in the transfer area.

Therefore, the developer conveyed by the conveyance roller 20 in the direction of arrow
0, or easily moves to the developing roller IO along the magnetic field formed between the magnetic poles.

Further, in the transfer area, the developer receiving roller 10 from the conveying roller 20 is positioned in the force direction of the arrow X with respect to the normal line from the magnetic pole S22 or the magnetic pole N+z.

Therefore, the developer is easily and easily transferred from the developing roller 10 to the conveying roller 20, and these rollers 10, . 20
No developer can get in between.

The toner consumed by development is transferred to a toner replenishing device 50.
will be replenished. Toner supply device 50 and toner supply path 9
Replenish toner. The replenished toner is stirred by the stirring blade 40.
The developer is conveyed to the empty chamber 5 by the rotation of the developer, and is mixed with the developer conveyed through the empty chamber 5.

Next, the position of the magnetic pole arranged at the opposing portion of the developing row 510 and the transport roller 20 was changed to observe the developer transport situation. The results are shown in the table below. Note that the gap between the developing roller 10 and the conveyance roller 20 at the closest position was 2.0 mm.

Further, the positional relationship of the magnetic poles was defined by an angle α.

As shown in the table, the relationship between the angle α and the developer conveyance situation is shown in the experimental results. As shown in the table, if the angle α is 85° or less, the occurrence of developer clogging is small and there is no problem in practical use.

However, when the angle α exceeded 90°, the developer entered between the rollers and the developing area became clogged with the developer, resulting in a significant deterioration in image quality.

〔Effect of the invention〕

As is clear from the above description, in a developing device that transfers developer between two rollers in which a sleeve rotates around a magnet, the arrangement of magnetic poles at the opposing portions of the two rollers is as follows:
The arrangement is such that the developer is received smoothly and the developer does not enter between the rollers.

Therefore, the developer is reliably moved from the C-roller to another roller, and the amount of developer conveyed to the development site is constant.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view of the developing device, FIG. 2 is a cross-sectional view of the developing device, and FIG. 3 is a diagram showing the arrangement of magnetic poles in the vicinity of the roller. S...Developing device, ■ Housing, 2. 3. 4゜5
・・Vacant room, 10・Developing roller, 11・・・Magnet, 12
... Sleeve, 20 - Conveyance roller, 21... Magnet,
22 Sleeve, 100...photoreceptor. Patent applicant: Minolta Camera Co., Ltd. Agent: Patent attorney: Mr. Maeda and 1 other person

Claims (1)

[Claims] (1) A first roller that includes a first fixed magnet and a first sleeve that rotates around the first fixed magnet, and is arranged to face the photoreceptor, a second fixed magnet, and the second fixed magnet. a second sleeve that rotates around the body in the same direction as the first sleeve, a second roller disposed opposite to the first roller; and a developer supply section that supplies developer to the second roller. ,
a regulating member that regulates the developer supplied to the second roller, and an A magnetic pole of the same polarity and an A magnetic pole of the same polarity along the rotational direction of the first sleeve at a portion of the first fixed magnet body facing the second roller. B magnetic poles are provided adjacently, and the first
A C magnetic pole and a D magnetic pole having different polarities from the A and B magnetic poles are provided adjacent to each other along the rotational direction of the second sleeve in the portion facing the roller, and a Points a, b, and a second point opposite to the magnetic poles C and D, respectively.
If the points on the outer circumference of the sleeve are c and d, then the quadrangle drawn by connecting these points a, d, c, and b forms a parallelogram, and ∠bad and ∠dcb form an angle of 85° or less. A developing device characterized in that the A magnetic pole, the B magnetic pole, the C magnetic pole, and the D magnetic pole are arranged.