JPH11311903A - Developing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To excellently recover carrier regardless of the installation condition of a carrier recovering device, to peel the recovered carrier and to excellently fix an image without causing offset at the time of fixing even in a transfer belt type device. SOLUTION: This device is equipped with a developing unit 11a developing an electrostatic latent image carried on a photoreceptor drum 10 with two- component developer consisting of the carrier and toner, and the carrier recovering device 25 removing the carrier adhering to the drum 10 at the time of developing by the developing unit 11a by sucking the surface of the drum 10, carrying and recovering the toner while it is rotated, and provided with a groove 31 going along in a direction orthogonal to the rotating direction on its surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a developing device provided in, for example, an electrophotographic apparatus.

[0002]

2. Description of the Related Art As a developing device of this type, there is a two-component magnetic brush type which develops using a two-component developer composed of a toner and a carrier. In the developing device of the two-component magnetic brush system, a carrier having a small particle diameter has been used for improving the image quality. The use of a small particle size carrier dramatically improves the image quality, but causes a problem that the carrier adheres to the photoreceptor.

[0003] However, if the carrier adhered to the photoreceptor can be removed and collected before transfer, the problem is reduced. Therefore,
Conventionally, measures have been taken to provide a carrier collecting device using a magnetic member behind the developing unit and in front of the transferring unit to collect the attached carrier from the surface of the photoreceptor.

[0004]

However, the conventional carrier recovery apparatus has a magnetic member having a specific magnetic field different from the magnetic field of the developing roller installed near the developing roller having a specific magnetic field. Since the adhered carrier is recovered by the magnetic force of the magnetic member, both magnetic fields have a complicated effect depending on the installation conditions, and the following problems occur.

That is, there is a problem that the carrier collecting device directly draws the developer from the developing roller. This is mainly because the magnetic force of the carrier collection device is the main pole of the developing roller,
This phenomenon occurs when it is large compared to the transport pole, etc., and when this phenomenon occurs, the developer is collected on the carry collection device,
As a result, the carrier collection efficiency is extremely reduced or negligible.

Further, when the amount of the accumulated developer increases, the phenomenon that the developer is locked between the roller and the carrier collecting device and the developer drops from the inside of the developing device is caused. When development is omitted, the function of the electrophotographic apparatus itself is impaired.

As described above, when the carrier collecting device is installed in the developing device of the electrophotographic apparatus, depending on the installation conditions, the collecting capacity is reduced, is completely absent, an image defect occurs, and the function of the electrophotographic apparatus is reduced. There was a problem that it was spoiled.

Conventionally, the carrier recovered from the photoreceptor is separated from the carrier recovery device by a blade and recovered in a developing device. However, the method in which the collecting carrier is peeled off by the blade has a problem that the contact portion of the blade eventually rubs, so that an appropriate contact angle and contact pressure cannot be obtained, and the ability to collect the carrier into the developing device is reduced. .

The present invention has been made in view of the above circumstances, and provides a developing device capable of satisfactorily recovering a carrier and peeling the recovered carrier irrespective of the installation conditions of the carrier recovery device. The purpose is to do.

[0010]

According to the present invention, an electrostatic latent image carried on an image carrier is formed by a two-component developer comprising a carrier and a toner. A developing unit for developing, and a carrier attached to the image carrier during development by the developing unit is removed by suction onto the surface, and the carrier is conveyed and recovered by rotating the carrier. And a carrier collecting means having a groove extending in a direction perpendicular to the direction.

According to a second aspect of the present invention, there is provided a developing means for developing an electrostatic latent image carried on an image carrier with a two-component developer comprising a carrier and a toner, and the image carrier at the time of development by the developing means. The carrier adhering to the surface is removed by adsorbing to the surface, and the carrier is conveyed and recovered by rotating the carrier, and a groove along the direction perpendicular to the rotational direction is formed on the surface in a predetermined direction in the rotational direction. A plurality of carrier collecting means formed at intervals.

According to a third aspect of the present invention, there is provided a developing means for developing an electrostatic latent image carried on an image carrier with a two-component developer comprising a carrier and a toner, and the image carrier at the time of development by the developing means. The carrier adhering to the surface is removed by adsorbing to the surface, and the carrier is conveyed and recovered by rotating the carrier, and a groove along the direction perpendicular to the rotational direction is formed on the surface in a predetermined direction in the rotational direction. A plurality of carrier collecting means formed at intervals, wherein the groove portion of the carrier collecting means is A ≧ B, where A is the width of the surface side along the rotation direction and B is the width of the inner bottom side. is there.

According to a fourth aspect of the present invention, there is provided a developing means for developing an electrostatic latent image carried on an image carrier with a two-component developer comprising a carrier and a toner, and the image carrier at the time of development by the developing means. The carrier adhering to the surface is removed by adsorbing to the surface, and the carrier is conveyed and recovered by rotating the carrier, and a groove along the direction perpendicular to the rotational direction is formed on the surface in a predetermined direction in the rotational direction. A plurality of carrier collecting means formed at intervals, wherein the groove portion of the carrier collecting means has a width A on the surface side along the rotation direction, a width B on the inner bottom side, and a depth C. , A ≧ B
And 0.5 ≦ A ≦ 4 mm and 0.5 mm ≦ C ≦ 2. Om
m.

According to a fifth aspect of the present invention, there is provided a developing means for developing an electrostatic latent image carried on an image carrier with a two-component developer comprising a carrier and a toner, and the image carrier at the time of development by the developing means. The carrier adhering to the surface is removed by adsorbing to the surface, and the carrier is conveyed and recovered by rotating the carrier, and a groove along the direction perpendicular to the rotational direction is formed on the surface in a predetermined direction in the rotational direction. A plurality of carrier collecting means formed at intervals, the carrier collecting means is an adsorption pole for adsorbing the carrier, a transport pole for conveying the carrier adsorbed by the adsorption pole,
It has a peeling pole which is the same as the transport pole and peels off the carrier transported by the transport pole.

According to a sixth aspect of the present invention, there is provided a developing means for developing an electrostatic latent image carried on an image carrier with a two-component developer comprising a carrier and a toner, and the image carrier at the time of development by the developing means. The carrier adhering to the surface is removed by adsorbing to the surface, and the carrier is conveyed and recovered by rotating the carrier, and a groove along the direction perpendicular to the rotational direction is formed on the surface in a predetermined direction in the rotational direction. And a plurality of carrier collecting means formed at intervals, wherein the carrier collecting means has a magnetic force of 30 to attract the carrier.
A magnetic pole for transporting the carrier attracted by the adsorption pole of 0 to 1200 G; a magnetic pole for transporting the carrier attracted by the magnetic pole being 300 to 1200 G; Having a peeling pole.

According to a seventh aspect of the present invention, there is provided a developing means for developing an electrostatic latent image carried on an image carrier with a two-component developer comprising a carrier and a toner, and the image carrier at the time of development by the developing means. The carrier is removed by adsorbing the carrier adhering to the surface thereof, and the carrier is conveyed and recovered by rotating the carrier. The carrier recovery means has a surface roughened surface.

According to another aspect of the present invention, there is provided a developing means for developing an electrostatic latent image carried on an image carrier with a two-component developer comprising a carrier and a toner, and the image carrier at the time of development by the developing means. The carrier adhered to the surface is removed by adsorption to the surface, and the carrier is transported and recovered by rotating the carrier, and the surface is subjected to a roughening treatment,
A carrier collecting means for setting the surface roughness to Rz = 5 to 50;

According to a ninth aspect of the present invention, there is provided a developing means for developing an electrostatic latent image carried on an image carrier with a two-component developer comprising a carrier and a toner, and the image carrier at the time of development by the developing means. The carrier adhered to the surface is removed by adsorption to the surface, and the carrier is transported and recovered by rotating the carrier, and the surface is subjected to a roughening treatment,
A carrier recovery means having a surface roughness of Rz = 5 to 50; wherein the carrier recovery means includes an adsorption pole for adsorbing the carrier, a conveyance pole for conveying the carrier adsorbed by the adsorption pole, and the same as the conveyance pole. The pole has a peeling pole that peels off the carrier carried by the carrying pole.

According to a tenth aspect of the present invention, there is provided a developing means for developing an electrostatic latent image carried on an image carrier with a two-component developer comprising a carrier and a toner, and the image carrier at the time of development by the developing means. The carrier adhered to the surface is removed by adsorbing on the surface, and the carrier is transported and recovered by rotating the carrier, and the surface is subjected to a roughening treatment so that the surface roughness becomes Rz = 5 to 50. Means for collecting the carrier, the magnetic force for adsorbing the carrier being 300 to 1200 G, and the magnetic force for conveying the carrier adsorbed by the attracting electrode being 300 to 12 G.
00G transport pole, the same pole as this transport pole, and the magnetic force for peeling the carrier transported by the transport pole is 300 to 1200G
Having a peeling pole.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to an embodiment shown in the drawings. FIG. 1 is a diagram showing an internal configuration of an electrophotographic apparatus as an image forming apparatus. 10 in FIG.
Is a photosensitive drum serving as an image carrier. The photosensitive drum 10 has a thickness of, for example, 2.5 mm and an outer diameter of 59.96 mm. Is given.

The photosensitive drum 10 is provided with a length of 340 mm so that the long side of the A4 size paper is conveyed in a direction in which the long side is conveyed in a direction perpendicular to the traveling direction. Is rotated at a predetermined speed corresponding to.

A developing device 1 as a developing means for developing a latent image by supplying toner (not shown) to the electrostatic latent image formed on the photosensitive drum 10 around the photosensitive drum 10
1. When the toner image obtained by developing the electrostatic latent image formed on the photosensitive drum 10 by the developing device 11 is transferred to a recording sheet supplied from a sheet supply unit such as a cassette (not shown), the toner Prior to the transfer by the transfer device described below, the pre-transfer static elimination device 12 and the developing device 11 attenuate the electrostatic attraction between the toner and the photoconductor drum 10 so that the transfer is efficiently performed on the recording paper. A transfer device 13 for transferring a toner image obtained by developing the electrostatic latent image formed on the drum 10 to recording paper supplied from a paper supply unit such as a cassette (not shown), and the toner image is transferred by the transfer device 13 A separation device 14 that attenuates the electrostatic attraction generated between the recording paper and the photosensitive drum 10, and exposes the recording paper of which the electrostatic attraction between the photosensitive drum 10 is weakened by the separation device 14. After the toner image is transferred onto the recording paper by the peeling device 15 that peels off from the surface of the drum 10 and the transfer device 13, the cleaning device 16 that removes and collects the transfer residual toner remaining on the photosensitive drum 10 and the cleaning device 16 The charge removing device 17 removes the charge remaining on the surface of the photosensitive drum 10 from which the transfer residual toner is collected, the charging device 18 charges the photosensitive drum 10 to a predetermined surface potential, and is uniformly charged by the charging device 18. A partial erasing LED unit 19 that irradiates a predetermined area of the photoconductor drum 10 with light to provide a non-image area of a predetermined size at the time of, for example, masking or reduced copying is arranged in this order.

It is to be noted that the image information of the object to be copied, which is taken in as the light / dark information of the light by the image reading section (not shown) from the space between the developing device 11 and the partially erasing LED unit 19 to the outer peripheral surface of the photosensitive drum 10 Is exposed via the mirror 20.

The developing device 11 has a diameter of about 30 mm.
The developing roller 21 includes a developing sleeve formed of an aluminum cylinder, which is a nonmagnetic material, and a magnet (described later with reference to FIG. 2) fixed inside the developing sleeve.

At a predetermined position on the outer periphery of the developing roller 21,
A doctor blade 24 fixed to the developing sleeve at a predetermined interval and for regulating the amount of developer conveyed toward the photosensitive drum 10 by the developing sleeve is provided. Further, at a position between the developing roller 21 and the pre-transfer static eliminator 12 and at a predetermined distance from the outer periphery of the photosensitive drum 10, an electrostatic latent image formed on the photosensitive drum 10 by the developing sleeve is provided. A carrier recovery device 25 is provided for recovering carriers adhered to the surface of the photosensitive drum 10 when developing an image.

The pre-transfer static eliminator 12 includes a photosensitive drum 10
The developing device 1 is provided with neutralizing light having a wavelength and a light intensity that does not cause undesired light fatigue to the photosensitive member of the developing device 1.
Before the transfer by the transfer device 13, the toner supplied to the electrostatic latent image on the surface of the photosensitive drum 10 by the transfer device 13 can be efficiently transferred to the recording paper in the transfer process by the transfer device 13 described below. , Toner and photoconductor drum 1
Attenuates electrostatic attraction between zero.

The transfer device 13 has a recording paper interposed between the photoconductor drum 10 and a corona discharge wire connected to a high-voltage power supply (not shown). The electrostatic latent image formed on the photoconductor of the photoconductor drum 10 is developed by the toner from the developing device 11 described above by supplying the photoconductor drum 10 with a charge having the same polarity as the charge provided to the photoconductor drum 10. The transferred toner image is transferred to the recording paper (not shown) by drawing it. The separation device 14 separates a corona discharge wire (AC) from a corona discharge wire connected to an AC high-voltage power supply (not shown).
Attenuates the electrostatic attraction generated between the recording sheet onto which the toner image has been transferred by the transfer device 13 and the photosensitive drum 10, and records the toner image transferred from the photosensitive drum 10. The paper can be peeled off without affecting the toner image (only electrostatically held on the recording paper).

The peeling device 15 is a claw-shaped member positioned so that the surface and the tip of the photosensitive drum 10 are slightly in contact with each other, and a degree of electrostatic attraction between the photosensitive drum 10 and the separating device 14. Is peeled off without affecting the toner image (only electrostatically held on the recording paper).

The cleaning device 16 includes the photosensitive drum 1
Transfer residual toner remaining on the photoreceptor drum 10 after the transfer device 13 has transferred the toner image to the recording paper, and has a rubber cleaning blade 26 formed so as to be able to contact the surface of the photosensitive drum 10 with a predetermined pressure. Is scraped off and collected.

The static eliminator 17 supplies static elimination light having a wavelength and a light intensity that does not cause undesired light fatigue to the photoreceptor of the photoreceptor drum 10, and the transfer residual toner is collected by the cleaning device 16. Photoreceptor drum 1
The charge remaining on the zero surface is removed.

The charging device 18 includes a corona wire (not shown) used for corona discharge, a shield case that surrounds the corona wire, and supplies a charging output discharged from the corona wire to only the photosensitive drum 10 and a corona wire. A grid electrode (not shown) is provided between the wire and the photosensitive drum 10 at a distance of about 1.5 mm from the surface of the photosensitive drum 10 to stabilize the surface potential provided to the photosensitive drum 10. Then, the photosensitive layer on the surface of the photosensitive drum 10 is charged to a predetermined surface potential by corona discharge from a corona wire connected to a charging power supply (not shown).

The grid electrode is used to take in a part of the corona discharge from the corona wire by a zener diode (not shown) and maintain the surface potential of the photosensitive drum 10 at a predetermined potential.

The partially erased LED unit 19 has a plurality of LED elements (not shown) arranged at a predetermined pitch along the axis of the photosensitive drum 10. Is selectively turned on, the charge provided to the photosensitive drum 10 by the charging device 18 is partially erased, and a non-image portion having an arbitrary size is provided.

Next, the developing roller 21 of the developing device 11 and the carrier collecting device 25 will be described in detail with reference to FIG. As described with reference to FIG. 1, the electrostatic latent image formed on the photosensitive drum 10 is developed by the toner supplied from the developing device 11. In actual development, the surface potential Vo of the photosensitive drum 10, the developing bias voltage Vb applied to the developing roller (ie, toner and carrier) of the developing device, the developing bias voltage Vb applied to the surface of the photosensitive drum 10 and the developing roller of the developing device 11 Contrast potential ΔV = (Vo−Vb) defined by the distance D from the surface 21
/ D, a centrifugal force Fr generated by the rotation of the developing roller 21 and affecting the toner and the carrier, and the electrostatic latent image formed on the photosensitive drum 10 due to various factors of the characteristic inherent to the toner and the carrier. It is impossible to supply only the toner by
Attachment to 0, that is, carrier attachment is inevitable.

Although it is possible to reduce this carrier adhesion, it is practically impossible to make it zero. In particular, in the case of a small-particle-size carrier, the magnetic coupling force with the developing roller 21 becomes weak. It is easily affected by Fr and the like, and the carrier adhesion phenomenon increases.

The carrier adhesion phenomenon generated in this way has a great adverse effect on the electrophotographic system. First, there is a problem in the developing device 11.

Since the carrier in the developer is reduced, the total amount of the developer in the developing device 11 is reduced, causing a problem in the developer transport system and leading to an image defect. The second is a case where the attached carrier attached to the photosensitive drum 10 is transferred onto the transfer paper.

In this case, an image defect such as a white spot occurs on the solid portion, which adversely affects the fixing device. In addition, the output image attached to the carrier, for example, in an electrophotographic apparatus, a document table using an automatic document feeder or the like,
In some cases, the carrier adheres to the other surface and causes a malfunction in the system.

Third, when the adhered carrier is not transferred onto the transfer paper, the carrier reaches the cleaning blade 26, which causes a problem that the life of the cleaning blade 26 is shortened.

The method for reliably transporting the carrier collected by the carrier collection device 25 into the developing device 11 will be described in detail. As shown in FIG. 2, the rotation center 21a of the developing roller 21 and the rotation center 10a of the photosensitive drum 10 are located on a straight line A. The center 21a of the developing roller 21 and the rotation center 25a of the carrier recovery device 25 are located on a straight line C. On the other hand, the center 25a of the carrier recovery device 25 and the center 10a of the photosensitive drum 10 are located on a straight line B.

The developing roller 21 includes a developing sleeve 21S
And the fixed magnet 2 located inside the developing sleeve 21S.
1M, the fixed magnet 21M has a first magnetic pole (hereinafter referred to as a main pole) magnetized so that the direction of the line of magnetic force rises along the straight line A, and the direction of the line of magnetic force is substantially parallel to the straight line C. A second magnetic pole (hereinafter, referred to as a carrier pole) magnetized so as to rise and two or three magnetic poles (not shown) provided in addition to the two magnetic poles are arranged.

The developing sleeve 21S is connected to the photosensitive drum 10
At a position facing the surface of the photoconductor drum 10, the direction in which the outer periphery of the photoconductor drum 10 moves is the same as the direction in which the surface of the photoconductor drum 10 moves. Have been. Further, the developing sleeve 21
The speed at which the outer periphery of S moves, that is, the peripheral speed of the sleeve, is set to have a predetermined magnification as compared with the moving speed of the surface of the photosensitive drum 10, that is, the peripheral speed of the drum.

As shown in FIG. 1, the carrier collecting device 25 comprises a cylindrical collecting sleeve 25S similar to the developing sleeve 21S of the developing roller 21, and a fixed magnet 25M located inside the collecting sleeve 25S. 25M
A first magnetic pole (hereinafter, referred to as an attracting pole) magnetized so that the direction of the magnetic force line rises along the straight line B, and a second magnetic pole (hereinafter, referred to as a transport pole) provided in addition to the attracting pole. ) And a third magnetic pole (hereinafter, referred to as a separation pole). The polarity of the first magnetic pole is the same as that of the main pole of the developing roller 21, that is, the first magnetic pole is magnetized to the N pole.

Further, the peeling electrode is preferably arranged at a position opposite to the attracting electrode on the circumferentially opposite side to the attracting electrode. Note that the transport pole is defined as 15 minutes from the line connecting the rotation center of the collection roller 25 and the rotation center of the photosensitive drum 10.
It is set in the range of 0 to 210 °. The polarity of the peeling electrode is an S-pole opposite to the polarity of the attracting electrode. The transport pole is an S pole which is opposite in polarity to the adsorption pole.

The speed at which the outer peripheral surface of the collecting sleeve 25S is moved, that is, the peripheral speed of the collecting roller is preferably 3
To 30 mm / s. Meanwhile, a groove 31 is formed on the surface of the collection sleeve 25S of the carrier collection device 25 along a direction orthogonal to the rotation direction of the collection sleeve 25S. This groove 31 is provided in the collecting sleeve 25.
A large number of S are formed on the surface of S at predetermined intervals along the rotation direction.

As shown in an enlarged view in FIG.
When the width dimension on the front side is A, the width dimension on the inner bottom side is B, and the depth dimension is C, there is a relation of A ≧ B, and 0.5 ≦ A ≦ 4.
mm, 0.5 ≦ C ≦ 2.0 mm. Further, the magnetic force of the above-mentioned adsorption pole, transport pole, and peeling pole, and the installation angle are set as shown in Table 1.

[0047]

[Table 1]

The magnetic force of each of the attracting pole, the transport pole and the peeling pole is 300 to 1200 G, and the angle of the attracting pole is −10 G.
+ 10 °, transport poles + 60 ° to 150 °, and peeling poles are transport poles +30 to 210 °.

However, the line connecting the center 10a of the photosensitive drum and the center 25a of the collecting device is 0 °, and the rotation direction (the direction opposite to the rotation direction of the photosensitive member) is plus. Next, the developing device 1
The flow of the developer (powder in which the toner and the carrier are mixed at a predetermined ratio) in 1 will be described.

The developer charged in the housing 11a is conveyed by the second mixer 23 shown in FIG. 1 to the back side (or the front side) in the direction perpendicular to the plane of FIG. On the other hand, the first mixer 22 conveys the developer conveyed by the second mixer 23 in the opposite direction, that is, on the front side (or the back side) in the direction orthogonal to the plane of FIG. Therefore, by the rotation of the first and second mixers 22 and 23,
The developer charged in the housing 11a is circulated in the housing 11a and is frictionally charged to a predetermined potential.

By the rotation of the first and second mixers 22 and 23, a predetermined amount of the developer circulating in the housing 11a is attracted to a magnetic pole (not shown) of the fixed magnet 21M of the developing roller 21 to develop the developer. The sleeve 21S is conveyed toward the doctor blade 24 shown in FIG. 1 by rotation.

The developer conveyed in the vicinity of the doctor blade 24 is attracted to a magnetic pole (not shown) provided in the vicinity of the doctor blade 24, and the rotation of the developing sleeve 21S causes the photosensitive drum 10 and the developing sleeve 21S to face each other. Is transported to the developing position where the image is to be developed. The developing position is defined near the position where the straight line A intersects with the developing sleeve 21S.

The developer conveyed to the developing position is formed into a brush shape along the lines of magnetic force from the main pole of the developing roller 21, and supplies only toner to the electrostatic latent image on the surface of the photosensitive drum 10 facing the developer. I do.

At the developing position, the developer on the developing sleeve 21S, which has formed a magnetic brush and supplied toner to the electrostatic latent image on the surface of the photosensitive drum 10, is charged by the magnetic force from the transport pole of the developing roller 21 and the developing sleeve. The toner is collected in the housing 11a by the rotation of 21S, and is mixed with the developer supplied from the first mixer 22 to the developing sleeve 21S.

As a result, the developer used for developing the electrostatic latent image on the photosensitive drum 10 and having the changed toner density is returned to the frictional charging process by the first and second mixers 22 and 23 again. It is.

In this frictional charging step, an amount of toner corresponding to the difference between the toner density detected by the toner density sensor (not shown) and the reference value is supplied from the toner tank (not shown), and the first and second toner tanks are charged. The toner is agitated and frictionally charged by the second mixers 22 and 23 and is supplied to the developing sleeve 21S again.

By the way, when the developer is formed in the shape of a brush toward the surface of the photosensitive drum 10 in the vicinity of the main pole of the developing roller 21, a magnetic brush is formed and the electrostatic latent image is developed. As described above, a small amount of the carrier in the developer is also attached to the surface of the photosensitive drum 10.

The carrier adhered to the photosensitive drum 10 is attracted to the attracting pole of the carrier collecting device 25, and the carrier is attracted to the transporting pole, and is also caught by the grooves 31 on the surface of the collecting sleeve 25S. As it rotates, it moves in the direction of the transport pole. Furthermore, although it is headed in the direction of the peeling pole with the rotation of the recovery sleeve 25S, the transport pole and the peeling pole are the same pole (S pole).
It is magnetically separated from the surface of the collection sleeve 25S, is again attracted to the developing roller 21, and is conveyed and collected into the housing of the developing device 11.

The carrier conveyed into the housing 11a by the collecting sleeve 25S is the developing roller 1
It is guided into the housing 11a by the magnetic force from the second transport pole. Therefore, the direction in which the collecting sleeve 25S is rotated is opposite to the direction in which the developing sleeve 21S is rotated. Next, the developing device 11 configured as described above
Are mounted on a Toshiba copier Leo Dry 6560 and the results of the test are described based on Tables 2 and 3.

[0060]

[Table 2]

[0061]

[Table 3]

Evaluation of carrier adhesion was performed using the above copying machine.
After setting the conditions in Table 2, 100,000 copies were made, and then a solid black image and one white image were obtained as a sample. In both samples, Δ indicates that no carrier was observed on the image, and X indicates that carrier adhesion was observed even a little.

The transportability of the developing sleeve 21S was determined by taking out the developing unit 11 and observing the developing sleeve 21S after copying 100,000 sheets in the same manner as described above. When no developer pool was formed below the developing sleeve 21S and between the carrier collecting device 25 and the developing sleeve 21S, it was judged as “〇”.

The transportability of the carrier recovery device 25 was also determined by observing the developing device 11 in the same manner as described above. When no developer pool was formed on the side of the developing sleeve 21S above the carrier recovery device 25, it was judged as Δ, when it was formed, Δ, and when the developer fell on the image, X was judged. The releasability of the carrier recovery device 25 was also determined by observing the developing device 11 as described above.

Observing the lower part of the carrier recovery device 25, it was determined that no carrier was left on the carrier recovery device 25 that passed through the peeling pole, and that the carrier was left as X. <Examples 1 to 18> The shape (mm) of the groove 31 on the collection sleeve 25S, the magnetic force (G) of the suction electrode, the transport electrode, and the separation electrode, and the installation position (°) were changed as shown in Table 2. In the range of Examples 1 to 18, it was found that carrier adhesion, transportability of the developing sleep 21S, and the recovery device 2
No problem occurred with respect to the transportability of No. 5 and the peelability of the recovery device 25.

As in the second embodiment, no problem occurs even if the width B of the inner bottom of the groove 31 shown in FIG. 4 is set to 0, that is, the shape of the groove 31 is made triangular. <Comparative Example 1> When the peeling electrode is removed under the same conditions as in Example 1, the carrier is deposited on the collecting device 25, and the transportability of the collecting device 25 and the developing sleeve 21S is deteriorated, and the effect of the attracting electrode is eventually lost. As a result, the carrier adhered to the image. <Comparative Example 2> When the groove 31 on the collecting sleeve 25S was removed, the result was that the transportability of the collecting device 25 was slightly inferior to that of Example 1. <Comparative Example 3> Groove 3 on recovery sleeve 25S in FIG.
In the case where the width B on the inner bottom side was wider than the width A on the front side of 1, the carrier remained at the end of the groove 31 and the releasability was deteriorated. <Comparative Example 4> When the depth C of the groove 31 on the collecting sleeve 25S was made shallow, carriers that survived the groove 31 were generated and the transportability of the carrier collecting device 25 was deteriorated. <Comparative Example 5> When the depth C of the groove 31 was increased, the peelability at the peeling electrode was deteriorated. <Comparative Examples 6 and 7> Regardless of whether the width of the groove 31 was narrow or wide, the transportability of the carrier recovery device 25 was deteriorated. <Comparative Example 8> The photosensitive drum 10
Carrier adhesion occurred on the image because the force of adsorbing the carrier adhering on the surface was reduced. <Comparative Example 9> When the magnetic force of the adsorption pole was increased, the developing sleeve 2 was
Since the carrier is directly drawn from above 1S, the transportability of the developing sleeve 21S is reduced. <Comparative Example 10> When the magnetic force of the transport pole was reduced, the transportability of the carrier recovery device 25 was reduced. <Comparative Example 11> When the magnetic force of the transport pole was increased, the carrier was directly drawn from above the developing sleeve 21A, so that the transportability of the developing sleeve 21A was reduced. <Comparative Example 12> When the magnetic force of the peeling pole was reduced, the peelability of the carrier recovery device 25 was reduced. <Comparative Example 13> When the magnetic force of the peeling pole was increased, the carrier was directly drawn from above the developing sleeve 21A, so that the transportability of the developing sleeve 21 was reduced. <Comparative Examples 14 and 15> The installation position of the suction force was −15 °, +
When the angle is set to 15 °, the adsorption pole is separated from the photosensitive drum 10, so that the carrier adhesion is deteriorated.

As described above, since the grooves 31 are provided on the collecting sleeve 25S of the carrier collecting device 25, the grooves 31 are formed.
, The carrier can be held and transported, and the transporting force of the carrier can be increased.

Accordingly, efficient carrier recovery can be performed, and the adverse effects due to carrier adhesion can be eliminated. Further, the carrier can be more efficiently recovered by installing the carrier adsorption pole and the carrier pole under appropriate conditions obtained as a result of the experiment.

Further, in this proposal, by providing a peeling pole in addition to the above-mentioned two poles of the attracting pole and the transport pole, a conventional blade for peeling off the carrier is not required, and the problem caused by abrasion of the blade and the like is eliminated. The point and the problem at the time of installation resulting from the required high precision were also able to be solved.

FIG. 5 shows a carrier recovery apparatus 40 according to a second embodiment of the present invention. As in the carrier collecting device 25 of the first embodiment, the carrier collecting device 40 has an attracting pole, a transport pole, and a peeling pole disposed inside the collecting sleeve 40S.

The surface of the collecting sleeve 40S of the carrier collecting device 40 is subjected to a roughening treatment so that the rough surface 4S is formed.
It is 1. Next, a description will be given of the result of a test conducted by modifying the developing device of Toshiba copier Leo Dry 6560 for the reduction amount of the developer in the carrier particle diameter and life and the carrier recovery effect of the recovery device 40.

The test was performed by measuring the amount of developer before and after copying 100,000 sheets. As shown in the graph of FIG. 6, it can be seen that the smaller the carrier particle size, the greater the amount of decrease in the developer after copying. It can also be seen that the installation of the collection device 40 prevents the developer from decreasing. It can also be seen that increasing the magnetic force of the adsorption pole of the recovery device 40 increases the recovery effect.

Considering that the generally used carrier has a particle size of about 60 (μm) and the effect of the decrease in the amount of developer, a carrier of 50 (μm) and a magnetic force of 200 (G) can be used. With a magnetic force of (G), a carrier of 40 (μm) can be used.

FIG. 7 is a graph showing the results of investigation on the effect of the transport pole and the effect of roughening the surface of the collecting sleeve 40S using a carrier having an average particle size of 30 (μm). It can be seen that, compared to a recovery apparatus having neither a transport pole nor a rough surface treatment, the recovery apparatus having a roughened surface has improved transport power, and the one provided with a transport pole has further improved transport power.

From this, it is understood that there is no problem even if the magnetic force of the attracting pole is set to 1500 (G) if the transport pole is used in combination with the rough surface treatment. However, if the magnetic force of the transport pole is too strong, the upper limit is 1200 (G) in this test, which adversely affects the transportability of the developer on the collection sleeve 40S. Next, the results of a test in which the carrier recovery device 40 is mounted on the developing unit of the Toshiba copier Leo Dry 6560 will be described with reference to Tables 4 and 5.

[0076]

[Table 4]

[0077]

[Table 5]

Evaluation of carrier adhesion was performed using the above copying machine.
After setting the conditions in Table 3, 100,000 copies were made, and then a solid black image and one white image were obtained as a sample. In both samples, Δ indicates that no carrier was observed on the image, and X indicates that carrier adhesion was observed even a little.

The transferability of the developing sleeve 21S was determined by copying 100,000 sheets in the same manner as described above, taking out the developing unit 11, and observing the developing sleeve 21S. When no developer pool was formed below the developing sleeve 21S and between the carrier collecting device 40 and the developing tank 21S, it was judged as “〇”.

The transportability of the carrier recovery device 40 was also determined by observing the developing device 11 in the same manner as described above. When no developer accumulation was formed on the side of the developing sleeve 21S above the carrier recovery device 40, it was determined as Δ, when it was formed, Δ, and when the developer fell on the image, X was determined.

The releasability of the carrier recovery device 40 was also determined by observing the developing device 11 in the same manner as described above.
The lower part of the carrier recovery device 40 was observed, and it was determined that no carrier was left on the carrier recovery device 40 that passed through the peeling pole, and that the carrier was left X.

<Examples 1 to 17> Experiments were conducted by changing the surface roughness Rz of the recovery sleeve 40S, the magnetic force (G) of the adsorption pole, the transport pole, and the separation pole, and the installation position (°) as shown in Table 3. Carrier adhesion in the range of Examples 1 to 17,
Transportability of the developing sleeve 21S, transportability of the collection device 40,
There was no problem with the releasability of the recovery device 40.

Example 18 The carrier particle size was 80 (μm
No.) did not cause any problem in the transportability and the like, but the image quality represented by the reproduction reproducibility of fine lines did not reach the target level.

<Example 19> The average carrier particle diameter was 20.
(Μm), carrier adhesion occurred even when the magnetic force of the adsorption electrode was increased to 1200 (G).

<Embodiments 20 and 21> Collection sleeve 40S
In the case where the surface was not subjected to the roughening treatment, the transportability of the recovery sleeve 40S was poor, and as a result of repeated copying, carrier adhesion eventually occurred. Although no treatment was performed, the surface roughness of Rz = 4 also showed a similar tendency, although the level was good.

<Examples 22 and 23> The magnetic force of the attracting electrode was 2
In the case where the carrier is reduced to 00 (G), carrier adhesion occurs in combination with a carrier having a small particle diameter, and conversely 1300 (G)
In the case of the one raised, the transportability of the recovery sleeve 40S deteriorated.

<Embodiments 24 and 25> The magnetic force of the transport pole was 2
If it is lowered to 50 (G), the transportability of the recovery sleeve 40S is deteriorated, while if it is raised to 1300 (G), the developer on the developing sleeve 21S is affected and the transportability of the developing sleeve 21S is hindered. .

<Example 26> The magnetic force of the peeling pole was 200
In the case of (G), the peeling performance from the recovery sleeve 40S was reduced.

<Examples 27 and 28> In both the case where the installation position of the adsorption electrode was set to -15 ° and the case where the installation position was set to 15 °, the carrier recovery ability was reduced, and carrier adhesion occurred.

<Example 29> When the peeling electrode was removed, the peeling performance of the recovery sleeve 40S was remarkably reduced, and carrier adhesion eventually occurred.

<Embodiment 30> When the transport pole was removed, the transportability of the recovery sleeve 40S was reduced, and carrier adhesion eventually occurred.

As described above, since the surface of the collecting sleeve 40S of the carrier collecting device 40 is subjected to the roughening treatment to form the roughened surface 41, the carrier transfer force can be increased. Accordingly, efficient carrier recovery can be performed, and the adverse effects due to carrier adhesion can be eliminated.

Further, the carrier can be more efficiently recovered by installing the carrier adsorption pole and the carrier pole under appropriate conditions obtained as a result of the experiment. further,
In this proposal, in addition to the above-mentioned adsorption pole and transport pole,
By providing a peeling pole, the blade used for peeling the carrier, which has been conventionally used, becomes unnecessary, and the problem caused by the abrasion of the blade and the problem at the time of installation due to the required high precision can be solved. Was completed.

[0094]

As described above, according to the present invention, since the groove is formed on the surface of the collecting sleeve, the carrier attracted onto the collecting sleeve is satisfactorily conveyed by being captured by the groove.
Carriers can be efficiently collected, and adverse effects due to carrier adhesion can be eliminated.

Further, since the surface of the collecting sleeve is subjected to a roughening treatment, the carrier attracted onto the collecting sleeve is captured by the roughened surface and conveyed satisfactorily. It can be removed.

Further, since the carrier adsorption pole and the carrier pole are installed under appropriate conditions obtained as a result of the experiment,
The carrier can be collected more efficiently.
In addition, since a peeling pole is provided in addition to the two poles of the adsorption pole and the transport pole, a conventionally used blade for peeling the carrier is not required. This has the effect that problems during installation caused by the height can be solved.

[Brief description of the drawings]

FIG. 1 is a configuration diagram illustrating an image forming unit according to an embodiment of the invention.

FIG. 2 is a diagram illustrating an arrangement configuration of a photoconductor, a developing roller, and a carrier collection device.

FIG. 3 is a configuration diagram showing a carrier collection device.

FIG. 4 is a diagram showing a groove shape of a collection sleeve.

FIG. 5 is a diagram showing a carrier recovery apparatus according to another embodiment of the present invention.

FIG. 6 is a graph showing the relationship between the magnetic force of the attracting pole of the carrier recovery device and the amount of decrease in developer.

FIG. 7 is a graph showing the effect of the magnetic force of the transport pole of the carrier recovery device.

[Description of Signs] 10: Photoconductor drum (image carrier) 11: Developing device (developing unit) 25: Carrier collecting unit: Adsorbing electrode: Transport electrode: Peeling electrode 31: Groove (groove) 41: Rough surface

Claims (10)

[Claims] 1. A developing means for developing an electrostatic latent image carried on an image carrier with a two-component developer comprising a carrier and a toner, and a carrier attached to the image carrier during development by the developing means. And carrier recovery means for transporting and recovering the carrier by rotating the carrier, and having a groove on the surface along a direction perpendicular to the rotation direction. Developing device. 2. A developing means for developing an electrostatic latent image carried on an image carrier with a two-component developer comprising a carrier and a toner, and the carrier attached to the image carrier at the time of development by the developing means. The carrier is transported and collected by rotating the carrier, and a plurality of grooves along the direction perpendicular to the rotational direction are formed on the surface at predetermined intervals in the rotational direction. A developing device, comprising: formed carrier collecting means. 3. A developing means for developing an electrostatic latent image carried on an image carrier with a two-component developer comprising a carrier and a toner, and a surface of the carrier adhered to the image carrier during development by the developing means. The carrier is transported and collected by rotating the carrier, and a plurality of grooves along the direction perpendicular to the rotational direction are formed on the surface at predetermined intervals in the rotational direction. And a carrier recovery means formed, wherein the groove of the carrier recovery means is A ≧ B, where A is a width on the surface side along the rotation direction and B is a width on the inner bottom side. Developing device. 4. A developing means for developing an electrostatic latent image carried on an image carrier with a two-component developer comprising a carrier and a toner; The carrier is transported and collected by rotating the carrier, and a plurality of grooves along the direction perpendicular to the rotational direction are formed on the surface at predetermined intervals in the rotational direction. And a carrier collecting means formed. The groove of the carrier collecting means has a width A on the front side along the rotation direction, a width B on the inner bottom side, and a depth C, wherein A
.Gtoreq.B, 0.5.ltoreq.A.ltoreq.4 mm, 0.5 mm.ltoreq.C.ltoreq.2. O
mm. 5. A developing means for developing an electrostatic latent image carried on an image carrier with a two-component developer comprising a carrier and a toner, and a carrier attached to said image carrier during development by said developing means. The carrier is transported and collected by rotating the carrier, and a plurality of grooves along the direction perpendicular to the rotational direction are formed on the surface at predetermined intervals in the rotational direction. And a carrier recovery means formed, wherein the carrier recovery means comprises an adsorption pole for adsorbing the carrier, a transport pole for transporting the carrier adsorbed by the adsorption pole, the same pole as the transport pole, and a transport pole. A developing pole having a stripping pole for stripping a carrier to be formed. 6. A developing means for developing an electrostatic latent image carried on an image carrier with a two-component developer comprising a carrier and a toner, and the carrier adhered to said image carrier at the time of development by said developing means is surfaced. The carrier is transported and collected by rotating the carrier, and a plurality of grooves along the direction perpendicular to the rotational direction are formed on the surface at predetermined intervals in the rotational direction. A carrier collecting means formed, wherein the carrier collecting means has a magnetic force of 300 to 1200 G for attracting the carrier, a carrier pole of 300 to 1200 G for transporting the carrier attracted by the magnetic attracting pole, A developing device having a separation pole having the same polarity as the transfer pole and having a magnetic force of 300 to 1200 G for separating the carrier transferred by the transfer pole. 7. A developing means for developing an electrostatic latent image carried on an image carrier with a two-component developer comprising a carrier and a toner; A carrier collecting means for removing the carrier by suction and transporting and recovering the carrier by rotating the carrier, the carrier recovering means having a roughened surface on the surface. 8. A developing means for developing an electrostatic latent image carried on an image carrier with a two-component developer comprising a carrier and a toner, and a carrier attached to said image carrier during development by said developing means. A carrier collecting means for removing the surface of the carrier by adsorbing, rotating and transporting the carrier to recover the surface, performing a roughening treatment on the surface, and setting the surface roughness to Rz = 5 to 50. A developing device, characterized in that: 9. A developing means for developing an electrostatic latent image carried on an image carrier with a two-component developer comprising a carrier and a toner, and a surface of the carrier adhered to said image carrier during development by said developing means. A carrier collecting means for removing the surface of the carrier by suction, transporting and recovering the carrier by rotating the surface, performing a roughening treatment on the surface, and setting the surface roughness to Rz = 5 to 50. The carrier recovery means has an adsorption pole for adsorbing the carrier, a transport pole for transporting the carrier adsorbed by the adsorption pole, and a separation pole for removing the carrier transported by the transport pole at the same polarity as the transport pole. A developing device, characterized in that: 10. A developing means for developing an electrostatic latent image carried on an image carrier with a two-component developer comprising a carrier and a toner, and the carrier adhered to said image carrier at the time of development by said developing means is surfaced. A carrier collecting means for removing the surface of the carrier by suction, transporting and recovering the carrier by rotating the surface, performing a roughening treatment on the surface, and setting the surface roughness to Rz = 5 to 50. The carrier collecting means includes an attracting pole having a magnetic force of 300 to 1200 G for attracting the carrier, a carrier pole having a magnetic force of 300 to 1200 G for transporting the carrier attracted by the attracting pole, and a carrier pole having the same polarity as the carrier pole. A peeling pole having a magnetic force of 300 to 1200 G for peeling off the carrier conveyed by the developing device.