JPH11282253A - Cleanrless image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily recover toner left on a photoreceptor drum by weakening the attaching force thereof. SOLUTION: This image forming device is provided with the photoreceptor drum 6, an electrification device 7, an exposure device 8, a transfer device 9 and a magnetic field forming device 41. By the forming device 41, a magnetic field for promoting the rotating movement of magnetic toner is formed at the outside surface of the drum 6 between the transfer device 9 and the electrification device 7 and on an opposite side to the developing device 8. It is preferable that a magnetic drum freely rotatably supported by a shaft being in parallel with the shaft of the drum 6 is used as the forming device 41 and fitted near the inside surface of the drum 6 so as to alternately make reverse polarity appear at the surface of the magnetic drum in the rotating direction. Besides, the image forming device is provided with a toner loosening member 42 at a position where it is opposed to the forming device 41 so as to be used together with the forming device 41 and brought into contact with the outside surface of the drum 6. When the loosening member 42 is vibrated, the attaching force of the toner is more easily weakened.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a cleaner-less image forming apparatus for collecting residual toner remaining on a photosensitive drum without using a cleaning device. In the present invention, the alternating magnetic field refers to a magnetic field that causes the magnetic toner on the surface of the photoconductor drum to rotate by magnetic force, thereby weakening the adhesion of the magnetic toner to the photoconductor drum. A specific example is a magnetic field having polarities different from each other.

[0002]

2. Description of the Related Art Conventionally, toner remaining on a photosensitive drum of an image forming apparatus is scraped off by a cleaning device provided around the photosensitive drum, and the scraped toner is accumulated in a collecting container. . In this method, it is difficult to reduce the size of the entire image forming apparatus because the cleaning device and the collection container are mounted. In addition, since the toner accumulates in the collection container, it is necessary to periodically replace the collection container and perform maintenance for discharging the toner. Therefore, a cleaning-less image forming apparatus has been proposed in which a residual toner is collected by a developing device without using a cleaning device and a collecting container.

[0003]

For example, Japanese Patent Application Laid-Open No. 7-7 / 1995
Japanese Patent No. 2717 discloses a capturing means for bringing a regulating member into contact with a photosensitive drum to guide the residual toner at the edge of the photosensitive drum into the width of the developing roller and capturing the toner falling below the regulating member. Is disclosed. However, the residual toner is generally considered to have a strong adhesive force to the photosensitive drum, and it is not sufficient to collect the toner by the developing roller only by guiding the toner into the width of the developing roller. Further, it is necessary to perform maintenance for processing the toner accumulated in the capturing unit.

SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus which is small in size and can be easily maintained, which can sufficiently collect residual toner on a photosensitive drum without using a cleaning device.

[0005]

According to the present invention, as a first invention, there is provided a photosensitive drum comprising: a photosensitive drum;
Provided is a cleaner-less image forming apparatus including a charging unit, a latent image forming unit, a developing unit, a transfer unit, and a magnetic field forming unit. A photosensitive layer is provided on the photosensitive drum,
It is charged by the charging means. The latent image forming means forms a latent image on the photosensitive drum. The developing unit is disposed to face the photoconductor drum, and forms a toner layer on the latent image with a magnetic toner. The transfer means transfers the toner layer onto recording paper. The magnetic field forming means forms a magnetic field between the transfer means and the charging means and on the surface of the photoreceptor drum opposite to the developing means for promoting the rotation of the toner.

In this apparatus, the toner remaining on the photosensitive drum after being transferred to the recording paper is caused to rotate by a magnetic field formed by the magnetic field forming means between the transfer means and the charging means. The toner is weakened in adhesion to the photosensitive drum by the rotation, and is collected by the developing unit after passing through the charging unit and the latent image forming unit. According to a second aspect of the present invention, there is provided a cleaner-less image forming apparatus in which the magnetic field forming means causes an alternating magnetic field to appear alternately in a circumferential direction of the photosensitive drum. The magnetic field forming means is attached between the transfer means and the charging means and on the side opposite to the developing means, near the inner surface of the photosensitive drum.

[0007] The residual toner passes through an alternating magnetic field alternately with the rotation of the photoreceptor drum, thereby promoting the rotation. As the magnetic field forming means, a commonly used means such as a magnet, a solenoid, and a coil can be used without any particular limitation. Further, as a third invention, there is provided a cleanerless image forming apparatus in which the magnetic field forming means is a magnetic drum rotatably supported on an axis parallel to the axis of the photosensitive drum. The magnetic drum is mounted between the transfer unit and the charging unit and on the opposite side of the developing unit, near the inner surface of the photoconductor drum, and applies an alternating magnetic field to the surface of the photoconductor drum in a rotational direction. Appear alternately.

The magnetic drum has an N pole and an S pole alternately appearing in the circumferential direction of the surface. By rotating the magnetic drum near the inner surface of the photosensitive drum, an alternating magnetic field is alternately applied to the surface of the photosensitive drum. Formed. According to a fourth aspect of the invention, there is provided a cleanerless image forming apparatus according to the first, second, or third aspect, further comprising: a toner loosening member; and a vibrating means for applying vibration to the toner loosening member. I will provide a. The toner loosening member is located between the transfer device and the charging unit, opposite to the developing device, in contact with the outer surface of the photosensitive drum, and at a position facing the magnetic field forming unit. Is provided.

The adhesion force to the photosensitive drum is further reduced by rotating the toner by the magnetic field forming means and bringing the toner loosening member such as a brush or a sponge member into contact with the surface of the photosensitive drum while vibrating. be able to. The vibration direction of the loosening member is not particularly limited in the circumferential direction, the axial direction, or the direction intersecting the circumferential direction.

According to a fifth aspect of the present invention, there is provided a cleanerless image forming apparatus in which a vibrator selected from a piezoelectric vibrator, a magnetic vibrator and a magnetic vibrator is used as the vibrating means in the fourth aspect. . For example, various vibrators such as a piezoelectric vibrator such as quartz, a magnetic vibrator such as barium titanate, and a magnetic vibrator such as ferrite can be used as the vibration means without any particular limitation.

According to a sixth aspect of the present invention, there is provided a cleaner-less image forming apparatus including a photosensitive drum, a charging unit, a latent image forming unit, a developing device, a transfer device, a toner loosening member, and a vibrating unit. provide. As described above, the photosensitive drum is provided with a photosensitive layer, and is charged by the charging unit. The latent image forming means forms a latent image on the photosensitive drum. The developing unit is arranged to face the photosensitive drum, and forms a toner layer on the latent image. The transfer means transfers the toner layer onto recording paper. The toner loosening member is provided so as to be in contact with the outer surface of the photosensitive drum between the transfer device and the charging unit and opposite to the developing device. The vibration unit applies vibration to the toner loosening member.

The toner loosening member and the vibrating means have a function of weakening the adhesion of the toner to the photosensitive drum as described above.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A cleanerless image forming apparatus to which an embodiment of the present invention is applied will be described with reference to FIG.
In FIG. 1, a document table 2 is provided on an upper surface of an image forming apparatus main body 1.
Are fixed, and a document holder 3 is provided on the document table 2 so as to be openable and closable.

Inside the main body 1 of the image forming apparatus, an exposure section 4 for reading a document is provided at an upper portion thereof. The exposure unit 4 includes a light source, a mirror, a lens unit, and the like. Further, an image forming section 5 for forming a toner image of a read document is provided at a central portion of the image forming apparatus main body 1. The image forming section 5 has a photosensitive drum 6 on the surface of which a latent image is formed. Around the photoreceptor drum 6, a charging device 7, a developing device 8, and a transfer device 9 are arranged.

At the lower part of the main body 1 of the image forming apparatus, a paper feeding unit 11 is provided.
Is provided. The paper supply unit 11 is provided in the image forming apparatus main body 1.
1, three sheet cassettes 13, 14, and 15 arranged vertically below the image forming apparatus main body 1, and a sheet cassette 13,
Large paper cassette 16 for storing a large amount of paper disposed on the right side of FIGS. 14 and 15 and paper for conveying paper stored in bypass table 12 or paper cassettes 13 to 16 to image forming section 5 And a delivery device 17.

The paper feeding device 17 is provided with the paper feed cassette 1
Paper feed rollers 18 to 21 for taking out the uppermost sheet in 3 to 16, separating rollers 22 to 25 for separating the taken out sheets one by one, and for guiding the separated sheets upward. , And three pairs of feed rollers 27 for transporting a sheet in the vertical transport path 26.

On the downstream side of the image forming section 5 in the sheet transport direction,
A paper discharge transport path 30 for transporting paper to the left side of the apparatus in FIG.
And a fixing unit 3 for fusing and fixing the toner image on the sheet.
1, a discharge roller 32 for discharging the sheet that has passed through the fixing unit 31, and a sheet discharge port 33 are provided. Below the sheet discharge port 33, a sheet discharge tray 34 for receiving discharged sheets is provided.

This image forming apparatus is provided with a magnetic drum 41, a brush 42, and the like in order to reduce the adhesion of the toner remaining on the photosensitive drum 6 to the drum. The magnetic drum 41 and the brush 42 are provided facing each other on the inside and outside of the surface of the photosensitive drum 6 as illustrated in FIG. The magnetic drum 41 is provided between the transfer device 9 and the charging device 7 so that a magnetic field for rotating the toner is formed on the outer surface of the photosensitive drum 6 on the side opposite to the developing device 8. It is located inside. Also,
The magnetic drum 41 is rotatably supported on an axis along the axial direction of the photosensitive drum 6 and has at least the same width as the photosensitive drum 6. On the outer surface of the magnetic drum 41, N poles and S poles alternately appear in the circumferential direction of the magnetic drum 41. When the magnetic drum 41 rotates, an alternating magnetic field alternates on the outer surface of the photosensitive drum 6. Occurs.

The brush 42 is in contact with the outer surface of the photosensitive drum 6 and is provided to face the magnetic drum 6. The brush 42 is arranged in the axial direction of the photosensitive drum 41,
It is provided at least over the width of the photosensitive drum 6. The brush 42 is supported by a support 43, and a piezoelectric vibrator 44 is attached to the support 43, and vibrates the brush 42. The piezoelectric vibrator 44 is connected to an electrode (not shown), and vibrates the brush 42 along the circumferential direction of the photosensitive drum 6.
The brush 42 may be used in place of a sponge member or the like.

Next, in particular, the magnetic drum 41 and the brush 4
Operation 2 will be described. The magnetic toner remaining on the photosensitive drum 6 after the transfer by the transfer device 9 is
When entering the magnetic field of 1, the magnetic toner alternately receives the alternating magnetic field and is caused to rotate, so that the adhesion to the photosensitive drum 41 is weakened. When the magnetic drum 41 rotates in the same direction as the photosensitive drum 6, the toner tends to rotate in the direction opposite to the rotation direction of the photosensitive drum, and when the magnetic drum 41 rotates in the opposite direction, the toner Tends to rotate in the same direction as the rotation direction of the photosensitive drum. Usually, the former tends to loosen toner. The rotation speed of the magnetic drum 41 may be such that the cycle in which the alternating magnetic field alternates appears to rotate the magnetic toner. Depending on the relationship with the rotation direction of the photosensitive drum, if the rotation speed is too slow, the toner rotates. It is difficult to make it. The vibration of the brush 42 is applied to the toner that rotates by the magnetic field, and the adhesion of the toner to the photosensitive drum is further reduced.

FIG. 3 is a view showing another embodiment of the magnetic field forming means and the toner loosening member. The magnet 51 is
The photosensitive drum 6 is disposed between the transfer device 9 and the charging device 7 and on the opposite side of the developing device 8 along the vicinity of the inner surface of the photosensitive drum 6. The magnet 51 is formed so that the N pole and the S pole alternately appear in the circumferential direction of the photosensitive drum, and has at least the width of the photosensitive drum 6 in the longitudinal direction of the photosensitive drum. As the magnet 51, a means for generating a magnetic field such as a magnet, a solenoid, or a coil can be used without particular limitation.

The fur brush 52 is provided at a position abutting on the outer surface of the photosensitive drum 6 and facing the magnet 51 in the same manner as described above. The bar 53 is provided at least over the width of the photosensitive drum 6 in parallel with the axis of the photosensitive drum, and has a shaft 54 and a rotating part 55 rotatably attached to the shaft 54. The fur brush 52 is planted on the outer peripheral surface of the rotating portion 55. A piezoelectric vibrator 56 is attached to the shaft 54 to vibrate the brush 52. The piezoelectric vibrator 54 is connected to an electrode (not shown), and vibrates the brush 42 along the axial direction of the photosensitive drum 6.

The magnetic toner having passed through the transfer device 8 is carried to the fur brush 52 while rotating by the rotation of the photosensitive drum 6 and the magnet 51. Fur brush 5
Numeral 2 vibrates while rotating due to the rotation of the photosensitive drum 6, and further weakens the adhesion of toner. The magnetic drum 41 and the magnet 51 and the brush 42 and the fur brush 52 to which the vibrating means are attached can be used independently as illustrated in FIGS.

[0024]

According to the present invention, the adhesive force of the magnetic toner remaining on the photosensitive drum can be reduced, so that the developing device can easily collect the residual toner. It is possible to sufficiently collect the residual toner on the photosensitive drum without using a cleaning device, and to realize a small-sized and easy-to-maintain image forming apparatus.

[Brief description of the drawings]

FIG. 1 is a cleaner-less image forming apparatus to which an embodiment of the present invention is applied.

FIG. 2 is a cleaner-less image forming apparatus including a magnetic drum and a brush to be vibrated.

FIG. 3 is a cleaner-less image forming apparatus including a magnet and a fur brush to be vibrated.

FIG. 4 is a cleaner-less image forming apparatus provided with a magnetic drum.

FIG. 5 is a cleaner-less image forming apparatus provided with a magnet.

FIG. 6 is a cleaner-less image forming apparatus provided with a brush to be vibrated.

FIG. 7 is a cleaner-less image forming apparatus equipped with a vibrated fur brush.

[Explanation of symbols]

 Exposure unit 6; Photoconductor drum 7; Charging device 8; Developing device 9; Transfer device 41; Magnetic drum 42; Brush 43; Support unit 44; Piezoelectric vibrator 51; Magnet 52; Fur brush 53; Bar 54; Shaft 55; rotating part 56; piezoelectric vibrator

Continuing from the front page (72) Inventor Masanori Kawasumi 1-2-2, Tamazo, Chuo-ku, Osaka-shi Inside Mita Kogyo Co., Ltd. (72) Inventor Yuichiro Hisakawa 1-2-28, Tamazuki, Chuo-ku, Osaka Mita Kogyo Inside the corporation

Claims (6)

[Claims] A photosensitive drum provided with a photosensitive layer; charging means for charging the photosensitive layer; latent image forming means for forming a latent image on the photosensitive drum; Developing means for forming a toner layer with a magnetic toner on the latent image; transfer means for transferring the toner layer onto recording paper; and a magnetic field for promoting the rotation of the toner, the transfer means and the charging means, And a magnetic field forming unit formed on the surface of the photosensitive drum opposite to the developing unit. 2. The image forming apparatus according to claim 1, wherein said magnetic field forming means is mounted between said transfer means and said charging means and on a side opposite to said developing means and near the inner surface of the photosensitive drum. The cleaner-less image forming apparatus according to claim 1, wherein the cleaner-less image forming apparatus alternately appears in a circumferential direction of the body drum. 3. The magnetic field forming means is mounted near the inner surface of the photosensitive drum between the transfer means and the charging means and on the side opposite to the developing means. 3. The cleaner according to claim 1, further comprising a magnetic drum rotatably supported on an axis parallel to the photosensitive drum, wherein the magnetic drum causes an alternating magnetic field to appear alternately in a rotation direction on a surface of the photoconductor drum. 4. Image forming apparatus. 4. A device is provided between the transfer means and the charging means, opposite to the developing means, at a position in contact with the outer surface of the photosensitive drum and opposed to the magnetic field forming means. The cleaner-less image forming apparatus according to claim 1, further comprising: a toner loosening member provided; and a vibration unit configured to apply vibration to the toner loosening member. 5. The cleanerless image forming apparatus according to claim 4, wherein said vibrating means uses a vibrator selected from a piezoelectric vibrator, a magnetic vibrator and a magnetic vibrator. 6. A photosensitive drum provided with a photosensitive layer, a charging means for charging the photosensitive layer, a latent image forming means for forming a latent image on the photosensitive drum, and a photoconductive drum disposed opposite to the photosensitive drum. Developing means for forming a toner layer on the latent image; transfer means for transferring the toner layer onto recording paper; and the opposite of the developing means between the transfer means and the charging means, A cleaner-less image forming apparatus, comprising: a toner loosening member provided in contact with an outer surface of a photosensitive drum; and a vibrating means for applying vibration to the toner loosening member.