JPH07104633B2 - Image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Outline] The present invention has achieved a predetermined object in an image forming apparatus in which an image exposing unit and a magnetic brush developing machine having a recording electrode are arranged to face each other with a transparent photoconductor therebetween. In order to collect an unnecessary toner image on the magnetic brush developing device, an unnecessary toner collecting means is provided upstream of the recording electrode in the moving direction of the photosensitive member, thereby obtaining a clear toner image without the unnecessary toner image on the photosensitive member. Is.

[Industrial application field]

The present invention relates to an image forming apparatus that forms a toner image on a bright portion on a photoconductor irradiated with image light and transfers the toner image to a display or recording paper.

Current copiers or high-speed, high-print quality printers generally use an electrophotographic recording system. This system is a so-called Carlson process in which recording is performed in the steps of uniform charging, image exposure, development, transfer, fixing, charge removal, and cleaning.

In the Carlson process, a corona discharger is used for uniform charging, transfer and static elimination. Since the corona discharger is configured to apply a high voltage of several KV to the corona wire, it requires a high voltage power source and is easily affected by humidity, dust, etc.
It has a drawback of low reliability. Further, ozone generated in a corona discharger produces an odor, and in recent years, ozone is harmful to humans.

Further, since the above-mentioned seven steps are required, there is a drawback that the device becomes complicated and the size becomes large.

In view of the above-mentioned problems, an image forming method has recently been proposed in which a corona discharger is unnecessary and the device is downsized.

[Conventional technology]

 FIG. 9 shows a schematic diagram of the prior art.

In the figure, the photoreceptor 1 is composed of a transparent substrate 1a, a transparent conductive layer 1b, and a photoconductive layer 1c, and the transparent conductive layer 1b is connected to the ground. The magnetic brush developing machine 2 provided on the photoconductive layer 1c side of the photoconductor 1 comprises a magnet roller 2a and a sleeve 2b, and the magnet roller 2a is freely rotatable. Further, a strip-shaped recording electrode 4 insulated from the sleeve 2b by an insulating film 3 is provided on the surface of the sleeve 2b. A voltage 6 having a polarity opposite to the carrier polarity (positive polarity in the figure) of the photoconductive layer 1c is applied to the recording electrode 4, and a voltage 7 having a polarity opposite to the recording electrode 4 is applied to the sleeve 2b. The developing device 2 is filled with a one-component developer or a two-component developer, and the developer 5 is conveyed in the direction of the arrow in the figure.

An image exposure unit 8 is arranged on the transparent substrate 1a side of the photoconductor 1. Examples of the image exposure means 8 include an optical system using an LED array, an optical system using a liquid crystal shutter, an optical system using electroluminescence, an optical system using a laser, and the like. The image exposure means 8 is arranged so that the optical axis of the exposure light intersects the recording electrode 4.

Next, the principle of image formation will be described.

When the photoconductive layer 1c is imagewise exposed in the portion A of the apparatus having the above-described structure, photocarriers are generated in the photoconductive layer 1c. Carriers having a polarity opposite to the voltage 6 applied to the recording electrodes 4 of the photocarriers move to the vicinity of the surface of the photoconductive layer 1c and become latent image charges 9.
In this way, in the exposed portion, the electrostatic capacity of the photoconductive layer 1c apparently increases, so that the amount of adhered toner increases, and a toner image with a certain degree of contrast is formed between the exposed portion and the non-exposed portion.

Next, in the portion B, the reverse voltage 7 is applied to the sleeve 2b and the developer is accumulated, so that the excess toner in the non-exposed portion is collected in the developing device 2 by electrostatic force and magnetic force. At this time, the toner in the exposed portion is also slightly collected, but the latent image charge 9
Due to the electrostatic restraint force of the toner charge, most of the toner remains on the photoconductor 1 and the toner image 10 is formed.

On the other hand, an unnecessary toner image 11 on the photoconductor 1 that has achieved a predetermined purpose, that is, a toner image that has been displayed on the image display device, a residual toner image after being transferred to a recording paper in the image recording device, etc. In the image formation, the electrostatic force due to the reverse voltage of the sleeve 2b and the magnetic force of the developing device at portion B are collected by the developing device and reused. In this way, the image exposure means 8
Since the photoconductor 1 is located on the opposite side of the developing device 2 with respect to the photoconductor 1, the unnecessary toner image 11 can be collected and the image can be formed at the same time.

[Problems to be solved by the invention]

In the conventional image forming apparatus, in order to remove the latent image charge 12 associated with the charge of the unnecessary toner image 11 and improve the toner recovery efficiency, a charge eliminating lamp or the like (not shown) is arranged in front of the image forming unit. However, since an electrostatic force acts between the toner charge and the latent image charge 12, it is not possible to sufficiently enhance the charge removal effect. Therefore, the unnecessary toner image 11 is collected in the image forming unit without sufficiently weakening the electrostatic force. In particular, in the developer pool of the portion B, the unnecessary toner image 11 is collected at the same time as the toner of the non-exposed portion is collected, but cannot be completely collected for the above reason. As a result, it appears as an afterimage when the next image is formed.

In view of the above-mentioned conventional problems, an object of the present invention is to provide an image forming apparatus capable of reliably collecting the toner remaining on the endless photoconductor in the magnetic brush developing machine.

[Means for solving problems]

FIG. 1 is a diagram illustrating the principle of the image forming apparatus according to the present invention. In the figure, reference numerals 1 to 12 are the same as in the prior art of FIG. 9, and the description thereof is omitted.

The image forming apparatus of the present invention is provided with the unnecessary toner collecting means 40 for forming a developer pool (C portion) for collecting unnecessary toner on the photoconductor 1 upstream of the recording electrode 4 in the moving direction of the photoconductor 1. It is a thing.

[Action]

In the image forming apparatus of the present invention, by disposing the unnecessary toner collecting means 40 that forms a pool (C portion) of the developer upstream of the recording electrode 4 in the moving direction of the photosensitive member, the developer 5 and the unnecessary toner are formed before the image formation. The image 11 is brought into contact with each other and collected in the magnetic brush developing machine 2 by utilizing electrostatic force and magnetic force and scraping force of the developer 5.

〔Example〕

FIG. 2 is an explanation of the first embodiment of the image recording apparatus according to the present invention, and FIG. 3 is a diagram showing the construction of the image forming section.

In the figure, 21 is an endless photosensitive film. As shown in FIG. 4, the photoconductor film 21 comprises a transparent conductive layer 21b made of a vapor deposited iTo (indium oxide) film on a transparent substrate 21a made of polyethylene terephthalate having a thickness of 100 μm. A thin functional separation type organic photoconductive layer having a thickness of 10 μm and including a (charge generation layer) 21c and a CTL (charge transport layer) 21d is provided. As described above, the photoconductor film 21
The transparent conductive layer 21b of the photoconductor film 2 is connected to the ground.
1 itself rotates in the direction of the arrow in the figure by a power system connected to the film driving roller 22.

Reference numeral 23 is a magnetic brush developing machine, and a magnet roller 23a provided inside a sleeve 23b rotates to carry toner.
As shown in FIG. 5, a copper foil strip recording electrode 25 insulated from the sleeve 23b by a polyimide film 24 and a magnetic iron piece 26 are attached to the surface of the sleeve 23b. This magnetic iron piece 26 functions to increase the height of the developer, and the sleeve 23b
Is electrically connected to. The magnetic pieces 26 may be made of electromagnetic soft iron, silicon steel, permalloy, ferrite, or the like.

As described above, the toner resistance of the magnetic brush developing machine 23 is 10 ² to 1
The conductive magnetic toner 29 of 0 ¹⁰ Ω · cm is filled. The toner is conveyed in the direction of the arrow in the figure, and a toner reservoir (section B) is formed downstream of the recording electrode 25 in the photosensitive member moving direction.

Since the hole transfer type was used for the photoconductive layers 21c and 21d in this example, a negative voltage was applied to the recording electrode 25 by the power supply 27. This voltage is -100 to -500V, preferably -150 to
-350V is suitable. In addition, the sleeve 22b and the magnetic iron piece 2
A positive voltage is applied to 6 by a power supply 28. This voltage is 0 to + 50V, preferably +10 to + 30V.

An LED array optical system 30 including an LED array 30a and a SELFOC lens array 30b is installed as an image exposure unit at a position facing the recording electrode 25 with the photoconductor film 21 interposed therebetween. The optical axis of the LED array optical system 30 is set so as to intersect with the center of the recording electrode 25 set to have a width of 1 to 5 mm.

Reference numeral 31 is a toner image formed on the photoconductor film 21. 32 is a recording paper, 33 is a conductive rubber roller for transfer,
At 34, the voltage (+200 to +600) is applied. Reference numeral 35 denotes a toner image transferred onto the recording paper, which is fixed on the recording paper 32 by the heat roller fixing device 36 to form a semi-permanent recorded image 37.

38 is a residual toner image remaining on the photoconductor film 21 after transfer. Reference numeral 39 is a charge eliminating lamp for removing charges of the residual toner image and latent image charges in the photoconductive layers 21c and 21d.

Next, an image recording procedure will be shown.

The photoconductor film 21 is rotated in the direction of the arrow, the magnet roller 23a of the developing machine 23 is rotated to convey the toner 29 in the direction of the arrow, and a toner reservoir is formed in the image forming portion, and the recording electrode 25, the sleeve 23b and Image exposure is performed by the LED array optical system 30 while applying a voltage to each of the magnetic iron pieces 26. Then, photocarriers are generated in the CGL 21c, and the holes therein move to the vicinity of the surface of the photoconductor inside the CTL 21d to become latent image charges. The charged toner image 31 held by the electrostatic force of the latent image charge is formed on the surface of the photoconductor film 21 according to the principle described in the section of the prior art.

Next, the toner image 31 is recorded on the recording paper 32 by using the transfer roller 33.
Electrostatically transferred to. The transferred toner image 35 is fixed on the fixing device 36.
Then, it is fixed on the recording paper 32, and a semi-permanent recorded image 37 is obtained.

On the other hand, the residual toner image 38 remaining on the photosensitive film 21 after the transfer is conveyed to the image forming unit.

In the image forming section, as shown in FIG. 3, a magnetic piece 26 is provided on the sleeve 23b on the upstream side in the moving direction of the photoconductor 1, and the magnetic piece 26 is provided on the magnetic roller 23a of the magnetic brush developing machine 23. A magnetic path is formed between the magnetic pole and the magnetic flux
Concentrate on the upper and lower ends of 6. Therefore, the spikes of the developer 29 are assisted, and the unnecessary toner collecting area C is formed. In the area C, the unnecessary toner image 38 is scraped off by the brush of the developer and collected in the developing machine 23 by the magnetic force. The scraped toner is retained by the magnetic force of the magnetic brush developing machine 23 and is reused.

Further, since the latent image charge associated with the charge of the residual toner image 39 is removed from the photoconductor 1 in the C area by the charge removal lamp 39, the scraping by the brush of the developer can be efficiently performed.

Further, the magnetic piece 26 is insulated from the sleeve 23b by using the insulating film 13, and the third voltage applying means 15 is used to apply the voltage having the same polarity as the voltage applied to the sleeve 2b to the magnetic piece 26. As a result, an electrostatic force that attracts the unnecessary toner image 11 to the magnetic brush developing machine 23 acts. As a result, the effect of the electric field is added to the magnetic effect of only the magnetic piece 26, so that the toner recovery efficiency is further improved.

According to the image recording apparatus as described above, the residual toner image 38 can be almost completely collected in the image forming unit, and at the same time, the image can be formed, so that a clear recorded image 37 without a residual image can be obtained. Further, since the toner usage efficiency becomes 100%, it is effective in reducing the lining cost.

Incidentally, in the above-described embodiment, the case where the static elimination operation of the static elimination lamp 39 is performed at the same time as the scraping operation of the unnecessary toner 38 by the toner bristles formed by the action of the magnetic iron piece 26 is explained, but the static elimination lamp 39 is not provided. Alternatively, only the magnetic iron piece 26 may be provided.

FIG. 6 is a diagram showing a second embodiment of the image forming apparatus according to the present invention. The difference from the first embodiment is that the magnetic iron piece 40
Is provided on the transparent substrate side which is the back surface of the photoconductor film 21,
That is, the height of the toner is increased to collect the residual toner 38.

FIG. 7 is a diagram showing a third embodiment of the image forming apparatus according to the present invention, and FIG. 8 is an explanatory diagram of the image forming section. The difference from the first embodiment is that the rotation direction of the motor that rotates and drives the magnet roller 23a is reversed and the toner conveying direction is reversed, and the pool of toner 29 is provided upstream of the photosensitive film moving direction to serve as toner recovery means. It is a point. Instead, a magnetic iron piece 41 is provided on the back surface of the photoconductor film 21 on the downstream side in the moving direction of the photoconductor film 21, and the height of the toner 29 is increased to provide a non-exposed portion toner collecting means. Moreover, as shown in FIG.
By providing the above, it is possible to sufficiently increase the height of the toner 29.

The above-described second and third embodiments also have the same effects as the first embodiment. That is, in the image forming section, the residual toner image 38 can be almost completely collected and at the same time an image can be formed, a clear recorded image 37 having no residual image can be obtained, and the usage efficiency of the toner 29 is 100%. It also reduces costs.

In each of the above-described embodiments, the one-component conductive magnetic toner is used as the developer, but the same effect as in the above-described embodiments can be obtained by using other one-component developer and two-component developer.

Further, it is needless to say that even if the present invention is applied to a display device that displays a toner image formed on a photoconductor, the same effects as those of the above-described embodiment can be obtained.

〔The invention's effect〕

According to the present invention, in an image forming apparatus in which a magnetic brush developing device having a recording electrode and an image exposing unit are arranged to face each other with a transparent photoconductor interposed therebetween, an unnecessary toner collecting unit is provided upstream of the recording electrode in the photoconductor moving direction. By providing the unnecessary toner image having a predetermined purpose is collected by the magnetic brush developing device, a clear toner image having no unnecessary toner image on the photoconductor can be obtained.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of the principle of the present invention, FIG. 2 is an explanatory diagram of the first embodiment, and FIG. 3 is an explanatory portion of an image forming unit of the first embodiment,
4 is a sectional view of the photoconductor film, FIG. 5 is a perspective view of the magnetic brush developing machine, FIG. 6 is an explanatory view of the second embodiment, and FIG.
FIG. 8 is an explanatory diagram of the third embodiment, FIG. 8 is an explanatory diagram of an image forming portion of the third embodiment, and FIG. 9 is a schematic diagram of a conventional technique. In the figure, 1 is a photoconductor, 2 is a magnetic brush developing machine, 3 is an insulating film, 4 is a recording electrode, 5 is a developer, 6 is a first voltage applying means, 7 is a second voltage applying means, and 8 is Image exposing means, 9 is a latent image charge, 10 is a toner image, 11 is an unnecessary toner image, and 40 is an unnecessary toner collecting means.

Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location G03G 15/08 502 F 507 B 15/09 Z 21/10 B41J 3/21 Z G03G 21/00 310

Claims (6)

[Claims] 1. A photoconductor (1) comprising at least a transparent or semitransparent conductive layer (1b) and a photoconductive layer (1c), and a photoconductive layer (1c) side of the photoconductor (1). A magnetic brush developing machine (2) arranged and provided with at least a sleeve (2b) for carrying a developer, and a recording electrode (4) provided on the sleeve (2b) and insulated from the sleeve (2b), A first voltage applying unit (6) for applying a voltage between the recording electrode (4) and the conductive layer (1b), and a voltage having a polarity opposite to that of the first applying unit (6) is applied to the sleeve ( Second voltage applying means (7) applied between 2b) and the conductive layer (1b), facing the recording electrode (4) on the conductive layer (1b) side of the photoconductor (1). In an image forming apparatus including an image exposure unit (8) provided at a position for performing image exposure, Toner magnetic brush developing apparatus (2)
And an unnecessary toner collecting means (40) for collecting the developer, and a pool (C) of the developer (5) is formed upstream of the recording electrode (4) in the moving direction of the photoconductor. Forming equipment. 2. The image forming apparatus according to claim 1, wherein the unnecessary toner collecting means is a magnetic piece (26) provided on the sleeve (2b). 3. The unnecessary toner collecting means is the same as the magnetic piece (26) which is insulated from the sleeve (2b) and is provided on the sleeve (2b) and the voltage applied to the sleeve (2b). A third voltage applying means (15) for applying a polar voltage between the magnetic piece (26) and the conductive layer (1b), the method according to claim (1). The image forming apparatus according to the item. 4. The unwanted toner collecting means further comprises a light source (39) for static elimination provided at a position facing the magnetic piece (26) with the photoconductor (1) interposed therebetween. The image forming apparatus according to claim (3). 5. The magnetic toner (40) provided on the electroconductive layer (1b) side of the photoconductor (1) as the unnecessary toner collecting means, according to claim (1). The image forming apparatus described. 6. The reservoir (C) is formed by transporting the developer (5) in the same direction as the moving direction of the photoconductor (1). The image forming apparatus according to item 1).