JPH08185066A - Image forming device - Google Patents

Abstract

PURPOSE: To prevent the generation of missing of a transferred image, etc., and to remarkably improve transfer accuracy. CONSTITUTION: This image forming device is constituted to be provided an endless belt-like photoreceptor 6 extended around a driving roller 2, a contact roller 3 and a peeling roller 4, to travel, an image forming process part 8 provided with a first electrifying charger 16, a laser optical system 17 and a developing device 20 which are arranged in order along the traveling path of the endless belt-like photoreceptor 6, a heating means disposed in the succeeding stage of the image forming process part 8 along the traveling path of the photoreceptor 6 and heating a recording sheet 10 and/or the photoreceptor 6 to the melting point of more of the dispersion medium of a solidified developer 22, a cooling device 29, a transfer peeling mechanism part 9 and a second electrifying charger 33 disposed along the traveling path of the photoreceptor 6, between the cooling device 29 and a recording sheet supplying part 11 and electrifying the recording sheet 10 closely stuck to the photoreceptor 6 to a polarity opposite to that of the solidified developer 22.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus for printing or image printing based on an image signal.

[0002]

2. Description of the Related Art Conventionally, in various printers, copying machines, etc., an electrophotographic process (so-called Carlson process) has been widely adopted as a method for forming an image. This electrophotographic process forms an image on a recording sheet through an image forming process such as charging, exposure, development (dry development or wet development), transfer or fixing. For example, according to a wet development method, a silver salt is used. It is possible to obtain resolution and gradation comparable to that of a photograph.

Among them, the wet developing method using a solidified developer is a solid in which developing particles are dispersed in a dispersion medium which is solid at room temperature and has a property of being melted by heating and solidified again by cooling. Wet development is carried out by heating the chemical developer to a molten state. This wet development method is very excellent in terms of storage stability and handling of the developer.

The applicant has previously proposed an image recording method using a solidified developer according to JP-A-5-197297, "Image recording method". This image recording method consists of the charging process →
It consists of an exposure process, a development process, a transfer / peeling process, and a cleaning process. The charging step and the exposure step are the same as the electrophotographic process, and the surface of the photoconductor on which the photosensitive layer is formed is
In the charging step, for example, negative charges are uniformly charged. In the next exposure step, the photosensitive member is subjected to laser irradiation based on an image signal by a semiconductor laser beam or the like, and the negative charge in the exposed portion disappears, whereby an electrostatic latent image is formed on the surface.

The developing step is a step of forming a developer image by supplying a developer to the surface of the photoconductor on which the electrostatic latent image is formed, and the solidified developer described above is melted as a developer. Used.

The transfer / peeling step is a step of bringing the recording sheet into close contact with the photosensitive member to transfer the solidified developer in a molten state onto the recording sheet and peeling the recording sheet from the photosensitive member.

The solidified developer remaining on the surface of the photoconductor is removed in the cleaning process, and the photoconductor is again subjected to a series of processes following the charging process.

In the above-mentioned prior image recording method, an endless belt-shaped photosensitive member which is wound around a driving roller and a plurality of guide rollers is used as the photosensitive member. Such an endless belt-shaped photoconductor, compared to the case where a photosensitive drum is used,
For example, it is characterized in that it is possible to secure a sufficient contact running path between the photoconductor and the recording sheet for reliable transfer, and to achieve downsizing of the apparatus.

[0009]

Although the prior application image recording method has the above-mentioned characteristics, in the transfer / peeling step, a part of the solidified developer to be transferred to the recording sheet side is transferred to the surface of the photoreceptor. There is a problem that the transfer image remains and a defective portion is generated in the transferred image.

As a method for improving the transfer accuracy, for example, a heating means is further provided between the developing step and the transferring / peeling step so that the solidified developer adhered to the surface of the photosensitive member is melted. It is considered to employ a method in which the recording sheet is strongly pressure-bonded to the surface of the photoconductor while being held.

However, in such a method, the solidified developer in a molten state is strongly pressure-bonded and spreads on the surface of the recording sheet, so that the edge portion is not formed sharply and a phenomenon such as image crushing occurs. There is also the problem that

Therefore, according to the present invention, when the developer image is transferred onto the recording sheet, the adhesive force between the developer and the endless belt-shaped photoreceptor is reduced and the adhesive force between the phenomenon agent and the recording sheet is increased. Therefore, the present invention has been proposed for the purpose of providing an image forming apparatus with improved transfer accuracy.

[0013]

SUMMARY OF THE INVENTION An image forming apparatus according to the present invention, which achieves this object, comprises an endless belt-shaped photosensitive member which is run by being stretched between a driving roller and a plurality of guide rollers, and an endless belt-shaped photosensitive member. First charging means arranged in sequence along the running path of the body to charge the entire surface of the endless belt-shaped photoconductor, and to expose the surface of the endless belt-shaped photoconductor based on an image signal to statically expose it. Exposure means for forming a latent image,
An image forming process section having a developing means for supplying a solidified developer in a molten state to the surface of an endless belt-shaped photoreceptor to develop an electrostatic latent image, and a recording sheet supply section to form a developer image. A recording sheet adhered on the surface of the endless belt-shaped photoreceptor, and heating means for heating the recording sheet and / or the endless belt-shaped photoreceptor to a temperature above the melting point of the dispersion medium of the solidified developer in advance; The recording sheet supplied from the recording sheet supply unit, which is arranged at the subsequent stage of the heating means along the running path of the endless belt-shaped photoconductor, is brought into close contact with the surface of the endless belt-shaped photoconductor, A transfer unit for transferring the formed developer image to the recording sheet, a cooling unit for cooling the endless belt-shaped photoreceptor and the recording sheet, and re-solidifying the solidified developer in a molten state on the surface of the recording sheet. ,
The peeling means for peeling the recording sheet from the endless belt-shaped photoconductor and the cooling means and the recording sheet supply section along the running path of the endless belt-shaped photoconductor are arranged to be in close contact with the endless belt-shaped photoconductor. The recording sheet includes a second charging unit that charges the recording sheet to a polarity opposite to that of the solidified developer.

Further, in the image forming apparatus according to the present invention, the driving roller has a diameter larger than that of the guide roller, and each means constituting the image forming process section is arranged along the outer peripheral portion of the driving roller. Configure.

[0015]

In the image forming apparatus according to the present invention having the above-described structure, the endless belt-shaped photosensitive member is covered by the driving roller and the guide roller and runs endlessly while the surface of the image forming process unit is covered. Charging, formation of an electrostatic latent image, and development of the electrostatic latent image by a solidified developer in a molten state are performed. The recording sheet supplied from the recording sheet supply section is brought into close contact with the surface of the endless belt-shaped photoreceptor in the transfer section in the course of further traveling. The developer image is brought into a molten state by heating the recording sheet and the endless belt-shaped photoreceptor to a temperature equal to or higher than the melting point of the solidified developer by the heating means. As a result, the developer image is transferred to the recording sheet that is in close contact with the endless belt-shaped photoconductor.

The second charging means disposed between the transfer section and the recording sheet supply section charges the recording sheet side with an electric charge having a polarity opposite to that of the developer image, thereby forming an endless belt-shaped photoreceptor. The developer particles in the developer image portion distributed on the surface side of are attracted to the recording sheet side. As a result, the developer image is electrostatically coupled with the recording sheet, and is transferred to the surface side of the recording sheet in a good state. The cooling unit cools the solidified developer in a molten state through the endless belt-shaped photoconductor to resolidify the solidified developer on the surface of the recording sheet. The peeling unit peels the recording sheet on which the image is transferred from the endless belt-shaped photoreceptor.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of the present invention will be described in detail with reference to the drawings. As shown in FIG. 1, the image forming apparatus 1 of the embodiment includes an endless belt-shaped photosensitive member 6 which is endlessly run by being stretched between a plurality of roller groups 2 to 5, and a traveling path of the endless belt-shaped photosensitive member 6. A cleaning mechanism section 7, an image forming process section 8, a transfer / peeling mechanism section 9, a recording sheet supply section 11 for supplying a recording sheet 10 to the transfer / peeling mechanism section 9, and an endless sheet. Belt-shaped photoreceptor 6
Ejection mechanism 1 for ejecting the recording sheet 10 peeled from the sheet
And 2.

The image forming apparatus 1 uses a solidified developer 22 in which developing particles are dispersed in a dispersion medium that is solid at room temperature and is melted by heating and resolidifies when cooled. Although not shown, the image forming apparatus 1
For example, a detection mechanism for detecting the joint between the start end and the end of the endless belt-shaped photoconductor 6 is provided, and the start position of image formation is controlled by the output of this detection mechanism.

The endless belt-shaped photoreceptor 6 comprises a flexible conductive substrate and a photosensitive layer made of an organic photoconductor or an inorganic photoconductor formed on the surface thereof. The end is joined to the end to form an endless belt. Consists of a belt. A group of rollers for moving the endless belt-shaped photosensitive member 6 is composed of a driving roller 2, a contact roller 3, a peeling roller 4, a backing roller 5, and the like. The driving roller 2 has a diameter of 100 mm, and the contact roller 3 and the peeling roller 4 each having a diameter of about 30 mm.
It is configured as a roller having a larger diameter. The contact roller 3 and the peeling roller 4 are arranged so as to be substantially flush with each other, and the peeling roller 4 and the driving roller 2 are configured so that part of their outer peripheral surfaces are flush with each other. It is arranged. Further, the contact roller 3 is arranged at the side of the drive roller 2. Therefore, the endless belt-shaped photoreceptor 6
Are laid over these roller groups 2 to 4 to form a substantially right-angled triangular running path.

The driving roller 2 is rotationally driven in the counterclockwise direction in FIG. 1 by a driving means (not shown), and supports the inner surface side of the endless belt-shaped photosensitive member 6 within a range of approximately half a circumference. The body 6 is allowed to run in a stable state and the occurrence of slackness or the like is removed. In the image forming apparatus 1, a cleaning mechanism unit 7 and an image forming process unit 8 are sequentially arranged in the rotational direction along the outer peripheral portion of the drive roller 2 on which the endless belt-shaped photosensitive member 6 travels stably.

The backing roller 5 corresponds to a developing device 20 which will be described later and which constitutes an image forming process section 8 arranged between the driving roller 2 and the contact roller 3, and the endless belt-shaped photoreceptor 6 is provided.
This endless belt-shaped photoconductor 6 is located inside the traveling path of
Support the inner surface side of. A transfer / separation mechanism section 9 is arranged in a horizontal traveling path formed between the contact roller 3 and the separation roller 4.

As described above, the cleaning mechanism section 7 is arranged on the outer peripheral portion of the drive roller 2 along the running direction of the endless belt-shaped photosensitive member 6 prior to the image forming process section 8. The cleaning mechanism unit 7 removes the static elimination lamp 13 that neutralizes the surface of the endless belt-shaped photoreceptor 6 that has been charged in the first image forming step, and the solidified developer 22 that adheres to the surface of the endless belt-shaped photoreceptor 6. And a blade 14 that operates. The endless belt-shaped photoconductor 6 is a charge eliminating lamp 1.
The negative charge, which is the adhesive force of the solidified developer 22, is eliminated by irradiating the blade 3 with the blade 3 in this state.
The solidified developer 22 remaining on the surface is removed by the abutting of the tip end of No. 4 on the surface. The removed solidified developer 22 is collected in the container 15. Of course, the blade 14 may be replaced with another mechanical cleaning means such as a fur brush or magnetic toner.

The endless belt-shaped photoconductor 6 travels to the image forming process unit 8 in a state where the cleaning process is performed on the surface thereof by the cleaning mechanism unit 7, and an image is formed on the surface. The image forming process unit 8 includes the first charging charger 1
6 and a laser optical system 17 and a developing device 20 which constitute an exposure unit.

The charging charger 16 is a device for uniformly charging the surface of the endless belt-shaped photoconductor 6 with, for example, negative charges, and the image forming apparatus 1 of the embodiment employs a scorotron. In this scorotron, a discharge wire that causes a corona discharge is arranged inside a charger housing in which an opening is formed so as to face the surface of the endless belt-shaped photoreceptor 6, and a mesh that functions as a grid electrode is formed in the opening. It is arranged. The scorotron gradually raises the voltage applied to the discharge wire, and when the electric field exceeds a critical value, a corona discharge is generated from this discharge wire, and a negative mesh is formed on the entire surface of the endless belt-shaped photoconductor 6 by the action of the mesh of the opening. Charge the electric charge in a uniform state.

The laser optical system 17 is a semiconductor laser light source 1.
8 and an optical system such as a reflecting mirror 19 or a condenser lens (not shown). Semiconductor laser light source 18
Is operated in accordance with an image signal sent from a control unit (not shown), and selectively irradiates the surface of the endless belt-shaped photoconductor 6 with laser light via an optical system. Endless belt type photoreceptor 6
The charged negative charges on the exposed surface portion are removed by being irradiated with the laser beam, and an electrostatic latent image corresponding to the image signal is formed.

The endless belt-shaped photosensitive member 6 is a laser optical system 1.
After the electrostatic latent image is formed at 7, the developing device 20 travels to the developing device 20 for development processing. The developing device 20 uses a solidified developer 22 in which positively charged developing particles are dispersed in an electrically insulating organic material that is solid at room temperature. The solidified developer 22 is repeatedly melted and solidified by heating and cooling as described above, and is supplied to the surface of the endless belt-shaped photoreceptor 6 in a molten state to form a developer image from the electrostatic latent image. To do.

The developing device 20 includes a general developer container 21 and
A supply roller 23 and a developing roller 24 are provided. The solidified developer 22 is stored in the developer container 21 in a solid state, and is heated by a heater (not shown) to be melted inside the developer container 21.

The supply roller 23 is rotationally driven in a state where a part of the peripheral surface is soaked in the melted solidified developer 22. The developing roller 24 is rotationally driven while being pressed against the peripheral surface of the supply roller 23, and is pressed against the surface of the endless belt-shaped photosensitive member 6 between the drive roller 2 and the backing roller 5. The molten solidified developer 22 is supplied to the surface of the developing roller 24 via the supply roller 23,
Further, it is supplied from the developing roller 24 to the surface of the endless belt-shaped photoconductor 6. Therefore, the endless belt-shaped photoreceptor 6
The solidified developer 22 adheres to the area corresponding to the electrostatic latent image portion formed in the laser optical system 17 to form a developer image.

The endless belt-shaped photosensitive member 6 is further driven to travel and folded back horizontally in the contact roller 3 to run, and at the folded back portion, the recording sheet supply unit 1 is provided.
The recording sheet 10 is supplied from 1. The recording sheet supply unit 11 includes a sheet supply roller 25 arranged at a side portion facing the contact roller 3 and a sheet feeding mechanism for omitting the details of feeding the recording sheets 10 stored from the sheet cassette 26 one by one. 27, and a guide roller mechanism 28 that conveys the fed recording sheet 10.

The recording sheet 10 has a guide roller mechanism 28.
Then, the sheet is fed from the sheet cassette 26 in a slightly upward state and is abutted against the outer peripheral surface of the sheet supply roller 25, so that the sheet supply roller 25 brings the sheet downward. Therefore, the recording sheet 10 is
The contact roller 3 is brought into close contact by being guided to the surface of the endless belt-shaped photoconductor 6 folded back in the horizontal direction with a slight pressure applied thereto.

A heater (not shown) is housed inside the contact roller 3 in order to maintain the molten state of the solidified developer 22 adhering to the surface of the endless belt-shaped photoreceptor 6 in the developing device 20. There is. As the heater, for example, a halogen lamp or the like having a length sufficient to heat the endless belt-shaped photosensitive member 6 over the entire width direction is used. On the other hand, in order to heat the recording sheet 10 to be supplied onto the surface of the endless belt-shaped photosensitive member 6 to the sheet supply roller 25 to a temperature equal to or higher than the melting point of the dispersion medium of the solidified developer 22, a heater (not shown) is housed inside. Has been done. The heater is, for example, the recording sheet 1
A halogen lamp or the like having a length sufficient to heat 0 over the entire width direction is used.

The endless belt-shaped photoreceptor 6 is arranged along the horizontal traveling path formed between the contact roller 3 and the peeling roller 4.
The vehicle is run with the recording sheet 10 in close contact with the surface.
Therefore, in the recording sheet 10, the solidified developer 22 in a molten state for forming a developer image on the surface of the endless belt-shaped photoreceptor 6 is compatible with the resin layer formed on the recording surface to form a developer image. Transfer is performed.

A transfer / separation mechanism section 9 is provided on a horizontal traveling path where the recording sheet 10 is superposed on the surface of the endless belt-shaped photosensitive member 6 and travels in the horizontal direction. Transcription
The peeling mechanism section 9 is composed of a cooling device 29, a peeling roller 4 and a peeling blade 30, and further applies a negative charge having a polarity opposite to the positive charge of the developer image formed on the surface of the endless belt-shaped photoreceptor 6. A second charging charger 33 that charges the surface of the recording sheet 10 is provided.
The cooling device 29 is transferred from the endless belt-shaped photoconductor 6 to the recording sheet 10 side by sliding the inner surface portion of the endless belt-shaped photoconductor 6 running on the horizontal traveling path across the entire width direction. The solidified developer 22 in the molten state is solidified.

The endless belt-shaped photosensitive member 6 is folded back toward the driving roller 2 when traveling to the peeling roller 4. As a result, the recording sheet 10 is peeled from the endless belt-shaped photoconductor 6 and is discharged to the discharging mechanism 12 along the peeling blade 30. A fixing device 31 is disposed in the discharge mechanism portion 12 in front of the receiving table 32.
The fixing device 31 is composed of, for example, a pair of heat rollers, and the solidified developer 2 transferred onto the recording sheet 10 is used.
The developer image of No. 2 is printed and fixed on the recording sheet 10.

The second charging charger 33 is located between the contact roller 3 which constitutes the recording sheet supply unit 11 and the cooling device 29, and is disposed in the vicinity of the surface of the endless belt-shaped photosensitive member 6. ing. As the second charging charger 33, a scorotron is used as in the first charging charger 16 constituting the image forming process unit 8, and the recording sheet 10 is charged with a negative charge from the non-transfer surface side to the entire surface. To be charged.

The solidified developer 22 forming a developer image on the surface of the endless belt-shaped photoconductor 6 is the endless belt-shaped photoconductor 6.
Are supported by a contact roller 3 having a built-in heating means and run, and the recording sheet 10 is conveyed by a sheet supply roller 25 having a built-in heating means, so that the temperature of each of the solidified developers 22 becomes higher than the melting point of the dispersion medium. Since the vehicle travels in a heated state, it is held in a molten state at the position of the second charging charger 33. The solidified developer 22 that forms a developer image is attached to the surface of the endless belt-shaped photoconductor 6 from which the negative charge has been removed, and the developer particles have a positive charge. Therefore, the developer particles in the developer image portion are attracted to the recording sheet 10 side, which is negatively charged by the second charging charger 33.

The endless belt-shaped photosensitive member 6 is folded back to the driving roller 2 side by the peeling roller 4,
After the recording sheet 10 is peeled off, the cleaning mechanism unit 7
Is driven to. Then, the endless belt-shaped photoreceptor 6 is subjected to the charge removal and cleaning processing as described above in the cleaning mechanism section 7, and the image forming process section 8 is again performed.
The next image forming operation is performed.

In the image forming apparatus 1 of the embodiment configured as described above, the recording sheet 10 is provided with the second charging charger 33 which charges the developer particles of the solidified developer 22 with the opposite polarity. As a result, the recording sheet 10
And a developer image, an electrostatic coupling force is generated. Therefore, the developer image formed on the surface of the endless belt-shaped photoconductor 6 is transferred onto the recording sheet 10 with extremely high accuracy, and the transfer image is prevented from being chipped.

Although the second charging charger 33 is arranged between the contact roller 3 which also serves as a heating means for the endless belt-shaped photosensitive member 6 and the cooling device 29, the heating means is provided separately. Of course, in the case of being, it is not arranged corresponding to the contact roller 3.

In the image forming apparatus 1 of the embodiment,
By using the belt system as the basic structure, it is possible to easily cope with large-scale image formation, and further, the manufacturing cost is reduced as compared with the image forming apparatus using the photosensitive drum.

Further, in the image forming apparatus 1 of the embodiment, since the solidified developer 22 having a property of being melted by being heated as a solid at room temperature and being re-solidified by being cooled is used, it is almost the same as the silver salt photograph. It is possible to obtain an image with resolution and gradation, and storage stability is also improved.

[0042]

As described in detail above, according to the image forming apparatus of the present invention, the second charging charger for charging the recording sheet with a charge having a polarity opposite to the charge of the developer particles of the solidified developer is provided. By being provided, an electrostatic coupling force is generated between the recording sheet and the developer image.
Therefore, the developer image formed on the surface of the endless belt-shaped photoreceptor is transferred to the recording sheet with extremely high accuracy,
Occurrence of chipping of the transferred image is prevented. by this,
The image forming apparatus prevents the occurrence of a missing transfer image,
The transfer accuracy is greatly improved.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a basic configuration of an embodiment of an image forming apparatus according to the present invention.

[Explanation of symbols]

 1 Image Forming Device 2 Driving Roller (Large Diameter Roller) 3 Contact Roller 4 Peeling Roller 6 Endless Belt-Shaped Photoreceptor 8 Image Forming Process Section 9 Transfer / Peeling Mechanism Section 10 Recording Sheet 11 Recording Sheet Supply Section 16 First Charger Charger 17 Laser Optical System 20 Developing Device 22 Solidified Developer 29 Cooling Device 33 Second Charging Charger

Claims (2)

[Claims] 1. An endless belt-shaped photosensitive member that is run while being stretched between a drive roller and a plurality of guide rollers, and an endless belt-shaped photosensitive member that is sequentially arranged along a running path of the endless belt-shaped photosensitive member. A first charging means for charging the entire surface, an exposing means for exposing the surface of the endless belt-shaped photoconductor on the basis of an image signal to form an electrostatic latent image, and a solidified developer in a molten state. An image forming process section having a developing means for developing the electrostatic latent image by supplying the toner to the surface of the endless belt-shaped photoreceptor, and an endless belt-like photoreceptor on which a developer image is formed supplied from the recording sheet supply section. A recording sheet adhered to the surface, heating means for heating the recording sheet and / or the endless belt-shaped photoreceptor to a temperature above the melting point of the dispersion medium of the solidified developer in advance, and a traveling path of the endless belt-shaped photoreceptor. Arranged downstream of heating means along The recording sheet supplied from the recording sheet supply section is brought into close contact with the surface of the endless belt-shaped photoconductor to transfer the developer image formed on the endless belt-shaped photoreceptor to the recording sheet, and the endless belt. Means for cooling the photosensitive member and the recording sheet to re-solidify the solidified developer in a molten state on the surface of the recording sheet, a peeling means for peeling the recording sheet from the endless belt-shaped photosensitive member, and an endless belt Second charging, which is disposed between the cooling means and the recording sheet supply unit along the running path of the photosensitive member and charges the recording sheet closely attached to the endless belt-shaped photosensitive member to the opposite polarity to the solidified developer. An image forming apparatus including a means. 2. The image according to claim 1, wherein the drive roller has a diameter larger than that of the guide roller, and each means forming an image forming process unit is arranged along the outer peripheral portion. Forming equipment.