JPH0814734B2 - Image recording device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Outline] The present invention is directed to an image forming unit in which a magnetic brush developing machine having a recording electrode and filled with a two-component developer and an image exposing unit are disposed so as to face each other with a transparent photoreceptor interposed therebetween. In an image recording device that electrostatically transfers the toner image formed in step 1 to a recording paper, a static elimination light source is provided between the image forming part and the electrostatic transfer part to prevent the carrier in the developer from being consumed. Further, the charge held by the carrier is removed to prevent carrier transfer, and the carrier is recovered by the developing machine.

[Industrial applications]

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

Current copiers or high-speed, high-quality printers
An electrophotographic recording system is generally used. This method is for uniform charging, image exposure, development, transfer, fixing, static elimination,
This is a so-called Carlson process in which recording is performed in the cleaning process.

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., and thus 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.

Recently, in view of the above problems, the corona discharger is unnecessary,
Image forming methods have been proposed that focus on downsizing of the apparatus.

[Conventional technology]

 FIG. 5 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. The inner transparent conductive layer 1b of the photoconductor 1 is connected to the ground. The photoconductor itself moves in the direction of the arrow in the figure.

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. In addition, sleeve 2b
A band-shaped recording electrode 4 insulated from the sleeve 2b by an insulating film 3 is provided on the surface of the. A photoconductive layer is formed on the recording electrode 4.
A voltage 6 having the opposite polarity to the carrier polarity (plus in the figure) of 1c is applied, and a voltage 7 having the opposite polarity to the recording electrode 4 is applied to the sleeve 2b.
Is applied. The developing machine 2 is filled with a two-component developer 5 composed of a conductive carrier and an insulating toner, and the developer 5 is conveyed in the direction of the arrow in the drawing, and a developer pool is formed.

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

Further, a transfer unit 12 for electrostatically transferring the toner image 10 formed by the image forming unit having the above-described configuration onto the recording paper 11 is provided.

 Next, the principle of image recording will be described.

When the photoconductive layer 1c is imagewise exposed in the area A of the image forming section, photocarriers are generated in the photoconductive layer 1c. Carriers (holes) having a polarity opposite to the voltage 6 applied to the recording electrode 4 among 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 part B, reverse voltage 7 is applied to sleeve 2b,
Moreover, by forming a pool of developer, 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.

Next, the toner image 10 on the photoconductor 1 is transferred onto the recording paper 11 by using the electrostatic transfer means 12. The transferred toner image 13 is
The image is fixed on the recording paper 11 by a fixing device (not shown) to form a semi-permanently recorded image.

On the other hand, the residual toner image 14 remaining on the photoreceptor 1 after transfer is
At the time of the next image formation, the electrostatic force due to the reverse voltage of the sleeve 2b and the magnetic force of the developing device at the portion B are collected by the developing device and reused. In this way, since the image exposing means 8 is on the opposite side of the developing device 2 with the photoconductor 1 interposed therebetween, the residual toner image 14 can be collected and the image can be formed at the same time.

[Problems to be solved by the invention]

In the conventional image recording apparatus, the toner image 10 formed on the photoconductor 1 is ideally composed of only the toner 10a. However, the carrier in the developer 5 is usually mixed in the toner image 10. Then, the toner 10a and the carrier 10
Both b reach the electrostatic transfer means 12 while holding the charge. In the electrostatic transfer means 12, both the toner 10a and the carrier 10b hold an electric charge, so that they are electrostatically transferred onto the recording paper 11. At this time, the transfer efficiency of the toner 10a is about 80%, and the transfer efficiency of the carrier 10b is about 50%. Therefore, although the transfer efficiency is low, the carrier is consumed.

As a result, in order to keep the mixing ratio of the toner and the carrier in the developer 5 constant, both the toner and the carrier are replenished,
It is necessary to control the mixing ratio. Further, when the developer 5 having a mixing ratio that is out of the mixing ratio margin is used, there is a problem that the printing quality is impaired, such as a decrease in printing density and an increase in fog density.

[Means for solving problems]

FIG. 1 is a diagram illustrating the principle of the image forming apparatus according to the present invention.

As shown in the figure, a static elimination light source 16 for irradiating the photoconductor 1 with light is provided between the image forming portion and the electrostatic transfer means 12. The other parts are the same as those in FIG. 5, and the same reference numerals are given to omit the description.

[Operation] When the charge eliminating light source 16 is provided as shown in FIG.
Among them, the charge of the carrier 10b and the latent image charge 9 are combined and neutralized, or the opposite charge (plus charge) can be injected into the carrier 10b. At this time, since the toner 10a is insulative, it cannot be neutralized with the latent image charge 9. Therefore, the toner 10a holds the electric charge, and the carrier 15 reaches the electrostatic transfer means 12 in the state of not having the electric charge. In the electrostatic transfer means 12, only the toner 10a is transferred to the recording paper 11 and the carrier 1
Most of 5 is not transferred and is collected by the developing machine 2 as an afterimage 14.

As a result, the carrier amount in the developer 5 becomes almost constant, and in order to keep the mixing ratio of the toner and the carrier constant,
Only the toner needs to be replenished, and the mixing ratio can be easily controlled.
Further, since the mixing ratio is constant, fluctuations in print quality can be reduced.

〔Example〕

FIG. 2 is a diagram showing an embodiment of the image recording apparatus according to the present invention.

In the figure, 21 is an endless photoconductor film. As shown in FIG. 3, the photoconductor film 21 is formed on a transparent substrate 21a made of polyethylene terephthalate having a thickness of 100 μm by ITO.
A transparent conductive layer 21b of (indium oxide) vapor-deposited film is provided, and as a photoconductive layer, a CGL (charge generation layer) 21c and a CTL (charge transport layer) 21d are formed. A conductive layer is provided. The transparent conductive layer 21b of the photoconductor film 21 as described above is connected to the ground, and the photoconductor film 21 itself rotates in the direction of the arrow in the figure by the power system connected to the film drive roller 22.

Reference numeral 23 is a magnetic brush developing machine, in which a magnet roller 23a provided inside a sleeve 23b is freely rotatable. Sleeve 23b
As shown in FIG. 4, the surface of the polyimide film
A strip-shaped recording electrode 25 made of copper foil insulated by 24 is attached. The magnetic brush developing machine 23 as described above is filled with a two-component developer 26 composed of a conductive carrier and magnetic insulating toner, and is conveyed in the direction of the arrow in the figure by rotation of the magnet roller 23b.

Since the hole transfer type is used for the photoconductive layers 21c and 21d in this embodiment, a negative voltage is applied to the recording electrode 25 by the first power supply 27. This voltage is -100 to -500V, preferably -150 to -350. A positive voltage is applied to the sleeve 23a by the second power source 28. This voltage is 0 to + 50V, preferably +10 to +30.

An LED array optical system 29 including an LED array 29a and a SELFOC lens array 29b is installed as an image exposing means at a position facing the recording electrode 25 with the photoconductor film 21 interposed therebetween. The optical axis of the LED array optical system 29 is arranged so as to intersect with the center of the recording electrode 25 set to have a width of 1 to 5 mm.

Reference numeral 30 denotes a toner image formed on the photoconductor film 21, which also contains a carrier. Reference numeral 31 denotes a charge eliminating lamp provided for the purpose of eliminating the charge of the carrier in the toner image 30, which is arranged on the back surface of the photoconductor film 21. 32 is a recording paper, which is so-called plain paper. 33 is a conductive rubber roller for transfer,
A voltage (+200 to + 600V) is applied by the power supply 34. Reference numeral 35 denotes a toner image electrostatically transferred onto the recording paper 32, which is fixed on the recording paper 32 by the heat roller fixing device 36 to form a semi-permanent recorded image 37.

Reference numeral 38 denotes a residual toner image remaining on the photoconductor film 21 after the transfer, which contains a carrier like the toner image 30.

 Next, an image recording procedure will be described.

The photosensitive film 21 is rotated in the direction of the arrow, the magnet roller 23a of the developing machine 23 is rotated to convey the developer 26 in the direction of the arrow to form a pool of the developer, and a voltage is applied to the recording electrode 25 and the sleeve 23b, respectively. With the voltage applied, image exposure is performed by the LED array optical system 29. Then, photocarriers are generated in the CGL21c, and the positive charge therein moves to the vicinity of the surface of the photoconductor inside the CTL21d to become a latent image charge. The charged toner image 30 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.

Since the charged toner image 30 also includes the carrier,
The charge eliminating lamp 31 combines and neutralizes the charge of the carrier and the charge of the latent image. At this time, since the toner is insulative, it is not neutralized with the latent image charges in the photoconductive layers 21c and 21d.

Next, the toner image 30 is recorded on the recording paper 32 by using the transfer roller 33.
Electrostatically transferred to. At this time, only the toner holding the charge is transferred, and the carrier is not transferred. Next, the transferred toner image 35 is fixed on the recording paper 32 by the fixing device 36, and a semi-permanent recorded image 37 is obtained.

On the other hand, the residual toner image 38 composed of the carrier and the toner remaining on the photosensitive film 21 after the transfer reaches the image forming portion,
Magnetic force of developing machine 23, scraping of developer 26, and sleeve 23b
It is recovered by the electrostatic force of the applied voltage and reused. Since the LED array optical system 29 and the developing device 23 face each other across the photoconductor film 21, as described above, the residual toner image
The collection of 38 and the next image formation can be performed simultaneously.

According to this embodiment, since the amount of carrier in the developing machine 23 can be kept substantially constant, only the toner needs to be replenished to keep the mixing ratio of the toner and the carrier constant, and the control of the mixing ratio is easy. became. Further, since the mixing ratio of the developer 26 is constant, the variation in the print quality of the recorded image 37 is reduced.

〔The invention's effect〕

According to the present invention, the carrier charge on the photoconductor is neutralized by the neutralization light source to prevent carrier transfer and collect it in the developing machine, so that the amount of carrier in the developing machine can be kept constant. Therefore, only the toner needs to be replenished with the developer, and the control of the mixing ratio of the toner and the carrier has become easy. Furthermore, by keeping the mixing ratio of the developer constant,
The fluctuation in print quality of the recorded image is also reduced.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory view of the principle of the present invention, FIG. 2 is an explanatory view of an embodiment of the present invention, FIG. 3 is a sectional view of a photosensitive film, and FIG. 4 is a perspective view of a developing machine. 5 and 5 are schematic views 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 two-component developer, 6 is a first voltage applying means, 7 is a second voltage applying means, 8 is an image exposure unit, 9 is a latent image charge, 10 is a toner image, 11 is a recording paper, 12 is an electrostatic transfer unit, 13 is a transfer image, 14 is an afterimage, 15 is a carrier without electric charge, and 16 is a discharge light source. Is.

Claims (1)

[Claims] 1. A photoreceptor (1) comprising at least a transparent or semi-transparent conductive layer (1b) and a photoconductive layer (1c) laminated together.
And a magnetic brush developing machine filled with a two-component developer (5) provided with a sleeve (2b) arranged on the photoconductive layer (1c) side of the photoreceptor (1) and carrying the two-component developer (5). (2), a recording electrode (4) provided on the sleeve (2b) so as to be insulated from the sleeve (2b), and a voltage is applied between the recording electrode (4) and the conductive layer (1b). And a second voltage for applying a voltage having a polarity opposite to that of the first voltage applying means (6) between the sleeve (2b) and the conductive layer (1b). An applying means (7); an image exposing means (8) provided on the side of the conductive layer (1b) of the photoconductor (1) and facing the recording electrode (4) for performing image exposure; An image provided with means (12) for electrostatically transferring the toner image (10) formed on the photoconductor (1) by the image exposing means (8) to the recording medium (11). In the image recording device, the electrostatic transfer means (1) is connected to the magnetic brush developing machine (2).
An image recording apparatus, characterized in that a static elimination light source (16) for irradiating the photoconductor (1) with light is provided between the steps (2) and (3).