JPH0215282A - Electrophotographic recording method and device thereof - Google Patents

Abstract

PURPOSE:To improve image resolution, to eliminate the need for the processing of exhausted toner, and to lengthen the life of a photosensitive body by developing toner onto a thin film stuck on the photosensitive body, and then transferring and fixing it onto a sheet by using a heating roll. CONSTITUTION:The photosensitive body is comprised of an electrically conductive substrate 1c, electric charge generating layer 1b, and electric charge shifting layer 1a; and said photosensitive body 1 is uniformly and negatively electrified by means of a contact electrifier 2a connected to a DC power source 2b. An exposing device 3 image-exposes the photosensitive body 1, and electron/hole is generated on the layer 1b. The hole ascends the layer 1a with the aid of the electric field of surface charge, and lowers surface electric potential; thereby an image part B and an image nonforming part W are created. At the same speed as the moving speed of the photosensitive body 1, the film 4 is moved so that it adheres to the photosensitive body 1; development onto the film 4 is performed through the use of toner 20a held on the surface of a non-magnetic sleeve 5a containing a magnet 5b. The film 4 is moved between the heating roller 11 and pressure roller 12, and transfer and fixing is ultimately performed onto the paper 14.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electrophotographic recording method and apparatus used in copying machines, printers, facsimiles, etc.

[Conventional technology and its problems]

In the conventional electrophotographic recording method, the surface of the photoreceptor is uniformly charged with a corona charger, then exposed according to the image information, and a toner image is developed directly on the surface of the photoreceptor. Many of them employ a method of obtaining recording paper by transferring the toner image onto paper and melting and fixing the toner image on the paper using a heating roll.

In the case of the above-mentioned recording method, the photoconductor is damaged due to the generation of ozone due to corona charging, and the toner used for developing the toner directly onto the photoconductor forms a film on the surface of the photoconductor, shortening the life of the photoconductor. There are drawbacks.

Furthermore, when toner is transferred onto paper, it is difficult to achieve 100% transfer, so it is essential to install a cleaner for this purpose, and furthermore, it is essential to dispose of the removed waste toner.

The electrostatic transfer method can generate high electrolysis with a single corona wire and has a simple structure, so it is often used in practical machines.

With a corona transfer device, it is impossible to apply an electric field that concentrates only on the desired transfer position, and the electric field before the desired transfer position may cause the toner to be inaccurately transferred to the root side, or the toner may be damaged on the paper after transfer. Due to the discharge generated during peeling, it is difficult to avoid scattering of 1-ner to the white background area near the image, causing a decrease in image resolution.

In addition, in the case of electrostatic transfer, it is generally necessary to use insulating toner, and since the charged toner is charged by frictional charging, oppositely charged toner may be generated or there may be a charge amount distribution, which may occur during development. It is difficult to maintain constant charging characteristics.

Many methods and devices have been proposed to solve the various problems mentioned above, and one example is as follows:
This device charges the photoconductor using contact charging to prevent the generation of ozone, but in this device, it is difficult to remove 100% of the waste toner with a cleaner, and the charging performance deteriorates over time, so it is not a desirable device. Another method is to install an electrical shield plate on the inlet side of the corona transfer device to prevent inaccurate transfer before transfer, but this device does not provide a perfect measure to prevent scattering. It is not
Further, toners have been proposed that have a high conductivity during development and a low conductivity during transfer, but it is difficult to stably change the conductivity to a desired degree.

[Problem that the invention seeks to solve]

The present invention develops toner on a thin film that is in close contact with a photoreceptor, and transfers and fixes it onto paper using a heating roll, without using components or elements that have the problems or drawbacks described above, such as an electrostatic transfer device. It is therefore an object of the present invention to provide an electrophotographic recording method and an apparatus therefor, which have excellent image resolution, do not require treatment of waste toner, and improve the life of a photoreceptor.

[Means and effects for solving the problems] In order to solve the above-mentioned problems, the present invention provides a method in which an insulating film is brought into close contact with the surface of the photoreceptor facing the developing device. moving at a speed to develop toner on the surface of the film, and peeling off the film from the photoreceptor after development;
Subsequently, the film is introduced into a heating roll to transfer and fix the toner image onto the paper, and the device includes a charger, an exposure device, a developer, and a predetermined gap around the photoreceptor. an insulating film is placed in close contact with the photoreceptor in the gap between the developing device and the photoreceptor, and is brought into close contact with a heating roll for toner transfer and fixing placed on the downstream side in the running direction of the film; The feature is that the film is run in synchronization with the moving speed of the photoreceptor.

The principle of forming an electrostatic latent image in the electrophotographic process is as follows: - By exposing a charged photoreceptor to light with image forming information, electron/hole pairs are generated, and electrons or genuine tags move through the charge transfer layer. The goal is to lower the surface potential.

The charge transfer layer (~photoreceptor film thickness) is -15~ for boat fishing.
When the insulating film is closely attached to the surface of the photoreceptor, the mobility of the insulating film is extremely small compared to that of the charge transfer layer, so electrons or holes stop at the interface of the charge transfer layer. However, if the thickness of the insulating film is sufficiently thin compared to the thickness of the photoreceptor film used, the surface potential of the exposed area will drop to the extent that image areas and non-image areas can be sufficiently distinguished on the surface of the insulating film. do.

Further, in consideration of the electrolytic strength for ensuring a sufficient amount of development of the toner in the developing section and the charging of the toner due to electrostatic induction, the film specifications must satisfy the following conditions.

That is, (1) the film thickness is preferably less than 20% of the photoreceptor film thickness or the average diameter of the toner, whichever is smaller; specifically, a film of about 1 to 5 microns is preferred.

(2) The film must have insulating properties with a volume resistivity of 10'2 Ω·cm or more to the extent that it does not cause latent image flow due to close contact with the photoreceptor.

(3) Furthermore, from the viewpoint of fixing properties, the surface temperature of the heating roll is 160°C.
It must be heat resistant to withstand temperatures from 210°C to 210°C.

From the above point of view, the film used in the present invention is preferably made of aramid polyimide.

The main parts constituting the electrophotographic process used in the recording method and apparatus of the present invention can be conventionally used parts except for the above-mentioned film, and the charger for the photoreceptor can be a corotron, scorotron or A contact charger can be used, and the contact charger generates little ozone, and in the present invention, the photoreceptor does not come into contact with the toner, so the charging performance does not deteriorate over time as described above, and the contact charger can be used. It is possible.

The developing method may be any of various conventionally known developing methods such as two-component insulating toner development, component magnetic insulating phenomenon, and one-component non-magnetic insulating development, but the feature of the present invention is that electrostatic transfer is unnecessary. In order to make the most of this, one-component conductive toner development is preferred.

The conductive toner phenomenon is most suitable for the present invention because a toner image faithful to the latent image can be developed on the film by electrostatic induction, and the structure of the developing device is simple. Also,
Since it is a conductive phenomenon, both normal and reverse rotations are possible.

By applying a DC voltage (developing bias voltage) substantially equal to the surface potential of the insulating film in the non-image area to the toner, the toner is developed on the insulating film according to the difference between the image area potential and the developing bias voltage.

Furthermore, by superimposing an alternating current on a direct current developing bias, the amount of toner development can be increased and the resolution can also be improved.

〔Example〕

Embodiments of the present invention will be described based on the drawings.

FIG. 1 shows the principle of using a negatively charged, layer-separated photoreceptor in order to explain the present invention in detail. In the figure, 1 is a photoreceptor; A charge generation layer lb and a charge transfer layer 1a are sequentially formed on the surface of a magnetic substrate IC. 2a is a contact charger;
A is connected to a DC power source 2b, and the photoreceptor 1 is uniformly negatively charged. Further, the photoreceptor 1 is irradiated with light according to the image information by the exposure device 3, and electrons/holes are generated in the charge generation layer 1b of the photoreceptor 1, and the holes are generated by the force of the electric field due to the surface charge. This is to raise the charge transfer tank 1a of the photoreceptor 1 and lower the surface potential.

When the film 4 is moved at a speed equal to the moving speed of the photoreceptor 1 as the photoreceptor 1 moves and is brought into close contact with the photoreceptor 1, charges are retained on the contact surface between the photoreceptor 1 and the film 4. The image is then guided to the developing device.

In FIG. 1, an example of forward development is shown in which the image area is indicated by B and the non-image area is indicated by W. The development method is one using a one-component magnetic conductive toner 20a, and the toner 20a is held magnetically. Non-magnetic sleeve 5 including magnet 1-5b for
The toner 20a is held on the surface a and moved close to the film 4 at an appropriate relative speed to the film 4.

Since the image area B has a potential difference with the toner 20a, a charge is injected into the toner 20a by electrostatic induction, and the toner overcomes the holding force of the magnet and is developed on the film 4 (toner 20b).

On the other hand, since the non-image area W has almost no potential difference with the toner 20a, it is not developed on the film 4.

Next, a first embodiment of the apparatus of the present invention will be described based on FIG. 2, and the same or equivalent parts will be described using the reference numerals used in FIG. 1.

In FIG. 2, a contact charger 2a, an exposure device 3. A developing device 5 and an eraser 6 are disposed with a predetermined gap from the photoreceptor 1.

The contact charger 2a is disclosed in, for example, Japanese Patent Application No. 62-35087.
An elastic roll type is used as shown in the DC power supply 2.
b to uniformly charge the photoreceptor 1.

The exposure device 3 is a laser-type scanning unit, and the development device 5 is a development device for one-component magnetic conductive toner. The toner rotates and a spike regulating plate (not shown) supplies toner with a constant spike height to the developing section, that is, to the gap between the insulating film 4 and the sleeve 5a.

The aluminum sleeve 5a is connected to a power source 5c which has alternating current superimposed on the direct current potential that is substantially the same as that of the non-image area.

Reference numeral 11 denotes a heating roll having an electric heater therein, and the film 4 is endlessly wound between the heating roll 11 and the photoreceptor 1. During the winding, the endless film 4 is wrapped around the photoreceptor 1. The photoreceptor 1 is inserted into a predetermined gap between the photoreceptor 1 and the developing device 5, and is wound tightly around the photoreceptor 1.

Further, the endless film 4 is placed on the photoreceptor 1.
Before bringing the film 4 into close contact with the film 4, the film 4 is brought into contact with a roll 7, which functions to smooth out wrinkles and adjust meandering, at an appropriate angle. The roll 7 described above is provided with grooves that form a curved shape in the unfolded state so as to spread outward from the center of the roll along the traveling direction of the film 4. This is done by slightly rotating the roll in the axial direction using the center of the roll as a fulcrum.

Meandering of the film is detected by an optical sensor 8 provided on the downstream side in the direction of travel of the film 4, and the roll 7 is feedback-controlled.

After meandering and smoothing out wrinkles, the film 4 is neutralized by a roll 9 whose surface is formed of a conductive rubber layer and which is electrically grounded.

As described above, the film 4 wound between the heating roll 11 and the photoreceptor 1 is separated from the photoreceptor 1, or the developed toner is held on the film 4 and conveyed to a transfer fixing section to be described later. However, if the toner retention is unstable at this time, as shown in FIG. An electric field is generated between the plates 15 and 16, and electrostatic force is applied to the charged toner in 4 directions of the film, thereby effectively holding the toner.

Furthermore, even if the toner is conductive, if the amount of charge is small, the charge will not leak and the toner will retain the charge, so the toner can be actively held on the film 4 using electrostatic force.

When the film 4 described above is wound and run between the photoreceptor 1 and the heating roll 11, the photoreceptor 1 and the heating roll 1
1, roll 7, and roll 9, tension adjustment rolls (not shown) may be installed with springs or the like in order to keep the film 4 in a tensioned state and run it without slipping. In addition, the roll 7 and roll 9
It can also be used as a tension adjustment roll.

Next, to explain the transfer fixing mechanism, the toner image developed on the film 4 is transferred to the heating roller 11 on the film 4.
The temperature is raised by contacting the The toner on the film 4 moves on a heating roller 11, and a pressure roller 12 whose surface is made of soft silicone rubber presses the heating roller 11, and a paper is placed between the heating roller 11 and the pressure roller 12. 14
The toner is transferred from the film 4 and fixed at the same time by pressing the paper 14 with the pressure roll 12.

When the glass transition point of the toner is 50° to 65°C and the melting start temperature in the flow tester is 90° to 120°C, the surface temperature of the heating roll 11 is about 160°C to 200°C, and transfer and fixation on paper is possible. be.

Although it is possible to transfer and fix substantially the entire amount of toner, in order to remove trace amounts of toner stains that adhere to the film 4, a felt cleaner 13 impregnated with silicone oil is used.
is arranged downstream of the heating roll 11.

Further, a cooling fan 10 for the film 4 is provided to cool the photoreceptor 1 so that the temperature does not exceed 50°C. For example, if the film is 5μ or less, the temperature is 200°C.
It takes less than 1 second to cool down from 50″C to 50″C.

To give a more specific example of this embodiment, the photoreceptor 1 is an organic photoreceptor in which the charge transfer layer has a thickness of 20 μm, and the film 4
is an aramid film with a thickness of 2.5μ and a volume resistivity of ~10I4Ω・CT11. Maximum continuous use temperature 200°C
It is. The developer is a component (1) magnetic conductive toner, and has a volume-based average diameter of 12μ.

The running speed of the film 4 was 9c+n/s, the surface potential of the non-image area on the film 4 was -400V, and the potential of the image area was -11.
It is 30■. Also, the developing bias voltage is -400 DC
■Peak to peak 1ooov, frequency 3000H
Adding z exchange. The distance between the photoreceptor 1 and the sleeve of the developing device 5 is set to 0.5 mm, and the film 4 is attached to the photoreceptor 1 in close contact with the distance.

A second embodiment of the apparatus of the present invention will be described based on FIG. Descriptions of the same actions will be omitted.

In addition, the same reference numerals are used for the same or equivalent members.

The insulating film 4 is supplied from the supply roll 20 to the roll 7, the static elimination roll 9. Photoreceptor 1. Heating roll 11. Further roll 2
1 and then wound onto a take-up roll 22, during which time the film 4 is attached under tension.
The roll 21 described above is for smoothing wrinkles and adjusting the meandering of the film 4 in the same manner as described in the first embodiment for the roll 7, and is used to smooth out the wrinkles and adjust the meandering of the film 4 during printing.
is made to travel from the supply roll 20 to the take-up roll 22 at the same speed as the photoconductor 1 heating roll 115 and the paper 14, and the developed toner is transported to the heating roll 11. The insulating film 4 is transferred and fixed by the rubber roll 12 and wound up by the take-up roll 22 . Then, when the remaining amount of the insulating film 4 on the supply roll 20 becomes small, the film 4 is reversely run from the take-up roll 22 toward the supply roll 20 and the film 4 is returned to the supply roll 20. Note that it is desirable that this reverse rotation operation be performed automatically.

The insulating film 4 in the second embodiment is an aramid film with a length of 30 m and a thickness of 2.5 μm, and is approximately 10 μm thick in A4 size.
The length is set to print 0 sheets of paper, but if you set the film length to be longer than the maximum number of continuous prints expected by the machine, and set an automatic sequence to always perform the reverse rotation operation at the end of printing. There is no need to temporarily interrupt printing and reverse the film during printing.

〔Effect of the invention〕

According to the electrophotographic recording method and apparatus according to the present invention, the following effects can be obtained.

(1) Since there is no contact between the photoreceptor and the toner, there is no toner filming on the photoreceptor, and the life of the photoreceptor is extended.

(2) Less ozone is generated, extending the life of the photoreceptor, and deterioration of toner due to ozone is reduced.

(3) Since conductive toner can be used, good developed images can be obtained.

(4) There is no need for a photoreceptor cleaner, which reduces damage to the photoreceptor, extends the life of the photoreceptor, and eliminates the need to dispose of waste toner.

(5) Since thermal transfer and fixing are performed simultaneously, a good image can be obtained on paper.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram for explaining the present invention in detail, FIG. 2 is an overall explanatory diagram showing the first embodiment of the present invention, FIG. 3 is an explanatory diagram of reinforcement when toner retention is unstable, and FIG. FIG. 4 is an overall explanatory diagram of the second embodiment of the present invention. 1: Photoreceptor 2a: Contact charger 3: Exposure device
4: Film 5: Developing device 6: Eraser 11: Heating roll 12: Pressure roll 14: Paper
20: Supply roll 22: Take-up roll Patent applicant Asahi Kasei Corporation

Claims (2)

[Claims] (1) An insulating film is brought into close contact with the surface of the photoconductor facing the developing device and moved at the same speed as the photoconductor, toner is developed on the surface of the film, and after development, the film is peeled off from the photoconductor, and then An electrophotographic recording method characterized by introducing the film into a heating roll to transfer and fix a toner image onto paper. (2) A charger, an exposure device, a developer, and an eraser are provided with a predetermined gap around the photoreceptor, and an insulating film is placed in close contact with the photoreceptor in the gap between the developer and the photoreceptor; An electrophotographic recording apparatus characterized in that the film is brought into close contact with a heating roll for toner transfer and fixing disposed on the downstream side in the running direction of the film, and the film is run in synchronization with the moving speed of a photoreceptor.