JP2001058425A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus dispensing with the replacement of a toner image support member and capable of being achieved in miniaturization and cost reduction. SOLUTION: An image forming apparatus has a toner image support member 101 having at least a pair of a dielectric layer 101c and a conductor layer 101b, a bias applying electrode 105b for applying the bias from a bias applying power supply 105a to the conductor layer 101b to inject charge of predetermined polarity in the conductor layer, an electrode head 102 injecting charge in the surface of the dielectric layer to form the electrostatic latent image corresponding to resolving power on the toner image support member and a switch 103 for selectively injecting charge having polarity reverse to the predetermined polarity in the dielectric layer through the electrode head 102.

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 forming an electrostatic latent image by discharging from an electrode head and performing toner development.

[0002]

2. Description of the Related Art In recent years, image forming apparatuses for printing on printing paper using toner, such as laser printers, have become widespread. Such an image forming apparatus is suitable for performing high-quality printing because it can form a high-resolution image. The above-described image forming apparatus will be described below with reference to the drawings.

FIG. 9 is a sectional view of a main part showing a conventional image forming apparatus.

In FIG. 9, reference numeral 201 denotes a toner image carrier,
202 is a toner image carrier roller, 203 is a charger, 20
4 is an exposure device, 205 is a development device, 205a is toner, 20
5b is a developing roller, 205c is a toner image, 206 is a transfer unit, 207 is a recording medium, 208 is a cleaning unit,
Reference numeral 209 denotes a static eliminator; 210, a fixing device; 211, a pressure roller; and 212, a heating roller. As shown in FIG. 9, the toner image carrier 201 includes a plurality of toner image carrier rollers 2.
02 is supported by a seamless belt. Further, the surface of the toner image carrier 201 is coated with an organic photoconductive material.

[0005] The operation of the image forming apparatus thus configured will be described.

First, the surface of the toner image carrier 201 is uniformly charged to about -600 V by the charger 203. An exposure unit 204 constituted by an optical device such as a laser irradiator or a polygon mirror irradiates a laser beam to the surface of the charged toner image carrier 201 based on an image signal, and changes the surface potential of the exposed portion to -100V. To about
An electrostatic latent image is formed on the surface of the toner image carrier 201. The developing device 205 storing the toner 205a is a developing roller 20 on which the negatively charged toner 205a is thinned and adhered.
5b is pressed against the toner image carrier 201 and the toner 205
a is transferred to the electrostatic latent image portion on the surface of the toner image carrier 201. The toner 205a adheres to the electrostatic latent image on the surface of the toner image carrier 201 to form a visible toner image 205c. The developing roller 205b is made of conductive urethane rubber or silicon rubber.

Next, the recording medium 2 is
The negatively charged toner image 205 c formed on the surface of the toner image carrier 201 is separated from the surface of the toner image carrier 201 by applying a positive voltage from the back side of the recording medium 207 to the recording medium 207. Transcribed.

Thereafter, the toner 205a remaining on the surface of the toner image carrier 201 is removed by using a cleaning means 208 having a cleaning blade, a cleaning brush and the like. Further, after removing the residual toner, the negative charge remaining on the surface of the toner image carrier 201 is neutralized by the neutralizer 209.

The recording medium 207 to which the toner image 205c has been transferred is sandwiched between a fixing device 210 composed of a pressure roller 211 and a heating roller 212 having a heat source therein, and the toner particles are melted by melting the toner particles. The image 205c is fixed on the recording medium 207.

[0010]

However, in the above-mentioned conventional image forming apparatus, since a photoconductor (organic photoconductive material coating layer) is used for the toner image carrier 201, an image is deteriorated due to photodeterioration of the photoconductor. It is necessary to replace the toner image carrier before the life of the forming apparatus, which has a problem in that maintenance-free and low running costs are hindered. Further, an exposure device 204 that generates a laser beam in the process of forming an electrostatic latent image is required. However, the exposure device 20 including an optical device such as a laser irradiation device and a polygon mirror is required.
No. 4 has a problem that it requires a large space and is expensive, which hinders miniaturization and cost reduction of the device.

In this image forming apparatus, it is not necessary to replace the toner image carrier, and it is required that the size and the price can be reduced by not using an exposure device.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an image forming apparatus which does not require replacement of a toner image carrier and can be reduced in size and cost.

[0013]

In order to solve the above-mentioned problems, an image forming apparatus according to the present invention comprises a toner image carrier having at least a pair of a dielectric layer and a conductor layer, a power supply for applying a bias to the conductor layer. A bias application electrode for applying a bias from the substrate to inject a charge of a predetermined polarity into the conductive layer, and forming an electrostatic latent image corresponding to the resolution on the toner image carrier by injecting the charge into the surface of the dielectric layer. There is provided a configuration having an electrode head and a disconnection means for selectively injecting a charge having a polarity opposite to a predetermined polarity into the dielectric layer via the electrode head.

Thus, there is no need to replace the toner image carrier, and the image forming apparatus can be reduced in size and cost.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An image forming apparatus according to a first aspect of the present invention includes a toner image carrier having at least a pair of a dielectric layer and a conductive layer, and a bias applied to the conductive layer from a bias applying power supply. A bias applying electrode for applying an electric charge of a predetermined polarity to the conductive layer by applying an electric charge, and an electrode head for injecting the electric charge to the surface of the dielectric layer to form an electrostatic latent image corresponding to the resolution on the toner image carrier. And a disconnection means for selectively injecting a charge having a polarity opposite to a predetermined polarity into the dielectric layer via the electrode head.

According to this configuration, since the dielectric is used for the toner image carrier, the life of the toner image carrier can be extended and the price can be reduced. In addition, since an exposure device is unnecessary, the apparatus can be downsized.
This has the effect of reducing costs.

According to a second aspect of the present invention, in the image forming apparatus of the first aspect, the electrode head is always in contact with the surface of the dielectric layer.

According to this configuration, since an exposure unit is not required, an effect is obtained that the size and cost of the apparatus can be reduced.

According to a third aspect of the present invention, in the image forming apparatus of the second aspect, the disconnection means is a switch, and the switch selectively grounds the electrode head.

According to this configuration, since only the electrode head is grounded, an exposing device is not required, and the device can be reduced in size and cost.

According to a fourth aspect of the present invention, in the image forming apparatus of the second aspect, the disconnecting means is a switch, and the switch selectively connects the electrode head to the bias applying section. Things.

With this configuration, since the electrode head is only connected to the bias applying section, an exposure device is not required,
This has the effect that the size and cost of the device can be reduced.

According to a fifth aspect of the present invention, there is provided the image forming apparatus according to the first aspect, further comprising contact means for selectively bringing the electrode head into contact with the surface of the dielectric layer in accordance with print data. This is to be connected to a predetermined potential portion.

According to this configuration, since an exposure device is not required, the size of the apparatus can be reduced and the price can be reduced.

According to a sixth aspect of the present invention, in the image forming apparatus of the fifth aspect, the electrode head is always connected to a ground as a predetermined potential portion.

According to this configuration, since an exposure unit is not required, the size of the apparatus can be reduced and the price can be reduced.

According to a seventh aspect of the present invention, there is provided the image forming apparatus according to the fifth aspect, further comprising a bias applying section as a predetermined potential section for generating a bias, wherein the electrode head is always connected to the bias applying section. It is what you have decided.

According to this configuration, since an exposure unit is not required, the size of the apparatus can be reduced and the price can be reduced.

According to an eighth aspect of the present invention, in the image forming apparatus according to the first aspect, a bias from an applied bias power supply is applied to the surface of the dielectric layer to charge the electric charge injected into the surface of the dielectric layer. A refresh roller for neutralizing is provided.

With this configuration, after the transfer of the toner image to the recording medium is completed, the charge injected to the surface of the dielectric layer is neutralized, and the power supply for applying a bias to the conductive layer is used to refresh the dielectric layer. Since it is also used as a power source for the device, it has an effect that the size and cost of the device can be reduced.

Hereinafter, embodiments of the present invention will be described with reference to FIGS.
This will be described with reference to FIG.

(Embodiment 1) FIG. 1 is a view for explaining the process principle of an image forming apparatus according to Embodiment 1 of the present invention, and FIG. 2 is an image forming apparatus according to Embodiment 1 of the present invention. FIG. 3 is a schematic cross-sectional view of a main part of the image forming apparatus according to the first embodiment.

In FIGS. 1 to 3, the toner image carrier roller 202, the developing device 205, the toner 205a, the developing roller 205b, the toner image 205c, the recording medium 207, and the fixing device 210 are the same as those in FIG. The same reference numerals are given and the description is omitted. 101 is a toner image carrier, 101
a is an insulator layer, 101b is a conductor layer, 101c is a dielectric layer, 102 is an electrode head, 103 is a switch, 104 is a transfer roller, 105 is a refresh roller, 105a is a bias application power supply, 105b is a bias application electrode,
Reference numeral 6 denotes a holding roller, and 107 denotes a transfer plate.

As shown in FIGS. 1 to 3, the image forming apparatus according to the present embodiment generally includes a toner image carrier 101 provided with a conductor layer 101b on an insulator layer 101a and a dielectric layer thereon. 101c, the conductor layer 1
01b can be applied with a bias. Further, the electrode head 102 is connected to the switch 103 and the like and is always in contact with the surface of the dielectric layer 101c, so that the electrode head 102 can be selectively grounded. Further, the toner image carrier 1
01 is an insulator polyethylene terephthalate (P
A conductive layer 101b made of aluminum or the like is provided on an insulating layer 101a made of ET) or the like.
Polyvinylidene fluoride (PV) which is a dielectric of about 0 μm
It has a belt-like shape (however, schematically indicated by a circle in FIG. 1) provided with a dielectric layer 101c made of DF) or the like, and has a configuration in which a bias can be applied to the conductive layer 101b. The electrode head 102 is configured such that the number of electrodes corresponding to the resolution is always in contact with the surface of the dielectric layer 101c. The electrode head 102 may be configured by forming an electrode on a printed board by etching, or by winding an enamel wire or the like around an insulator, solidifying the resin with a resin, and then shaving and exposing the cross section of the enamel wire. it can. Further, the electrode head 102 is connected to the switch 103 and is configured to be grounded in accordance with the print data.
The switch 103 includes a relay using an electromagnet, a contact using a piezoelectric element, or the like. Developing roller 205b
Is applied with a developing bias having the same polarity as the charging polarity of the toner. To the transfer roller 104, a bias having a polarity opposite to the polarity of the charged toner is applied. The refresh roller 105 is made of conductive silicon rubber, urethane rubber, or a conductive brush, and has a configuration capable of applying a high voltage.

The printing operation of the thus configured image forming apparatus will be described.

As shown in FIG. 1, the bias application electrode 10
5b through the conductive layer 1 from the bias applying power supply 105a.
A bias of -800 V is applied to 01b, and when the surface potential of the dielectric layer 101c is measured, the apparent surface potential is -800V. At this time, the voltage becomes 0 V when the applied bias is turned off. When an image forming operation is instructed by a control unit (not shown) of the image forming apparatus, the toner image carrier roller 202 is rotated, and the toner image carrier 101 is moved to an arrow A.
Start rotating in the direction. At the same time, the electrode head 102 is grounded by the operation of the switch 103 in accordance with the content of the image to be formed, whereby the bias applied to the conductor layer 101b is -800 V, and positive charges are injected into the surface of the dielectric layer 101c. Is done. The portion where the positive charge is injected is apparently neutralized, and the surface potential becomes 0V. Also,
Since -800 V appears on the surface where the ground is not grounded, an electrostatic latent image is formed on the surface of the dielectric layer 101c.

In the above steps, the toner image carrier 101
The electrostatic latent image formed above reaches the position of the developing device 205 by rotating the toner image carrier 101 in the direction of arrow A. The developing roller 205b disposed in the developing device 205 rotates and comes into contact with the toner image carrier 101. The toner 205a is thinned and adhered to the developing roller 205b, and a developing bias of about -300V is applied. As a result, the toner image carrier 101 is
The electrostatic latent image is developed by the toner 205a attached to the surface of the developing roller 205b while being moved while being nipped between the toner image carrier 101 and the nipping roller 105b.
A toner image 205c is formed thereon.

When the toner image 205c is formed on the toner image carrier 101 by the above operation, the toner image carrier 10
1 to transfer the toner image 205 c onto the recording medium 207. When the recording medium 207 is fed from a paper feeding unit (not shown) on the transfer plate 107 in the direction of arrow B, the bias of the polarity opposite to that of the toner 205 a is applied to the rear surface of the recording medium 207 by contacting the transfer roller 104. And the toner image 205 c on the toner image carrier 101 is
7 is transferred. The toner image 205c transferred onto the recording medium 207 is conveyed into the fixing device 210, and is fixed on the recording medium 207 by the action of heat, pressure, or the like, and the image forming operation is completed.

On the other hand, the toner image 2 on the toner image carrier 101
After the toner image carrier 05c is transferred onto the recording medium 207, the positive charge on the dielectric layer 101c is neutralized (refreshed) by the toner image carrier 101 coming into contact with the biased refresh roller 105, and the original charge is restored. To return to the state described above, and prepare for the next image forming operation.

In the present embodiment, the parallel transfer type image forming apparatus has been described as an example. However, the image forming apparatus of the parallel transfer type is used to transfer the toner image by moving the toner image carrier in a direction orthogonal to the recording medium. It is also possible to apply the present invention to a transfer type image forming apparatus.

As described above, in the present embodiment, the toner image carrier 101 is formed of the insulating layer 101a and the conductive layer 101.
b, the dielectric layer 101c, the electrode head 102 is always in contact with the surface of the dielectric layer 101c, and the switch 103
As a result, the need to use a photoconductor for a toner image carrier, which has been a problem of the related art, is eliminated, and an exposure device is not required. This makes it possible to make the toner image carrier maintenance-free and to reduce the size and cost of the image forming apparatus.

(Embodiment 2) FIG. 4 is an explanatory view of the process principle for explaining the process principle of an image forming apparatus according to a second embodiment of the present invention, and FIG. 2 is similar to the case of the first embodiment. FIG. 3 is a cross-sectional view of a main part of a periphery of a toner image carrier of the image forming apparatus according to the present embodiment. FIG. 3 is a schematic diagram of a main part of the image forming apparatus according to the present embodiment, similarly to the first embodiment.

In FIG. 4, a toner image carrier 101, an insulator layer 101a, a conductor layer 101b, and a dielectric layer 101
c, electrode head 102, switch 103, transfer roller 1
04, refresh roller 105, bias application power supply 1
05a, bias applying electrode 105b, toner 205a,
Developing roller 205b, toner image 205c, recording medium 20
7 is the same as that in FIG.
Description is omitted. 108 is a bias application unit. FIG.
As shown in FIG. 4 to FIG. 4, the image forming apparatus according to the present embodiment is substantially the same as that of the first embodiment.
As No. 01, the conductor layer 101b was provided on the insulator layer 101a, and the dielectric layer 101c was provided thereon, so that a bias could be applied to the conductor layer 101b. Further, the electrode head 102 is connected to the switch 103 and the like, and is always in contact with the surface of the dielectric layer 101c. However, the present embodiment is different from the first embodiment in that the electrode head 102 can be selectively connected to the bias applying unit 108. In addition, the toner image carrier 101 has a conductor layer 101b made of aluminum or the like on an insulator layer 101a made of an insulator such as polyethylene terephthalate (PET).
And a dielectric layer 101c made of polyvinylidene fluoride (PVDF), which is a dielectric having a thickness of about 50 μm, is formed thereon, and a belt can be applied to the conductive layer 101b. I have. The electrode head 102 has a number of electrodes corresponding to the resolution of the dielectric layer 1.
01c is always in contact with the surface. The electrode head 102 may be configured by forming an electrode on a printed board by etching, or by winding an enamel wire or the like around an insulator, solidifying the resin with a resin, and then shaving and exposing the cross section of the enamel wire. it can. Further, the electrode head 102 is connected to a switch 103 and is connected to a bias applying unit 108 according to print data. The switch 103 is configured by a relay using an electromagnet, a contact using a piezoelectric element, or the like. Developing roller 205
A developing bias having the same polarity as the charging polarity of the toner is applied to b. To the transfer roller 104, a bias having a polarity opposite to the polarity of the charged toner is applied. The refresh roller 105 is made of conductive silicon rubber, urethane rubber, or a conductive brush, and has a configuration capable of applying a high voltage.

The printing operation of the thus configured image forming apparatus will be described.

As shown in FIG. 4, as shown in FIG.
5b through the conductive layer 1 from the bias applying power supply 105a.
A bias of -800 V is applied to 01b, and when the surface potential of the dielectric layer 101c is measured, the apparent surface potential is -800V. At this time, the voltage becomes 0 V when the applied bias is turned off. When an image forming operation is instructed by a control unit (not shown) of the image forming apparatus, the toner image carrier roller 202 is rotated, and the toner image carrier 101 is moved to an arrow A.
Start rotating in the direction. At the same time, by connecting the electrode head 102 to the bias applying unit 108 by the operation of the switch 103 according to the content of the image to be formed, positive charges are injected into the surface of the dielectric layer 101c. Where the positive charge is injected, it is apparently neutralized, and the surface potential becomes zero.
V. Further, since -800 V appears on the surface of the portion not connected to the bias applying section 108, the dielectric layer 1
Thus, an electrostatic latent image is formed on the surface of 01c.

In the above steps, the toner image carrier 101
The electrostatic latent image formed above reaches the position of the developing device 205 by rotating the toner image carrier 101 in the direction of arrow A. The developing roller 205b disposed in the developing device 205 rotates and comes into contact with the toner image carrier 101. The toner 205a is thinned and adhered to the developing roller 205b, and a developing bias of about -300V is applied. As a result, the toner image carrier 101 is
The electrostatic latent image is developed by the toner 205a attached to the surface of the developing roller 205b while being moved while being nipped between the toner image carrier 101 and the nipping roller 105b.
A toner image 205c is formed thereon.

When the toner image 205c is formed on the toner image carrier 101 by the above operation, the toner image carrier 10
1 to transfer the toner image 205 c onto the recording medium 207. When the recording medium 207 is fed from a paper feeding unit (not shown) on the transfer plate 107 in the direction of arrow B, the bias of the polarity opposite to that of the toner 205 a is applied to the rear surface of the recording medium 207 by contacting the transfer roller 104. And the toner image 205 c on the toner image carrier 101 is
7 is transferred. The toner image 205c transferred onto the recording medium 207 is conveyed into the fixing device 210, and is fixed on the recording medium 207 by the action of heat, pressure, or the like, and the image forming operation is completed.

On the other hand, the toner image 2 on the toner image carrier 101
After the toner image carrier 05c is transferred onto the recording medium 207, the positive charge on the dielectric layer 101c is neutralized by bringing the toner image carrier 101 into contact with the biased refresh roller 105 to return to the original state. Return to prepare for the next image forming operation.

In the present embodiment, the parallel transfer type image forming apparatus has been described by way of example. However, the toner image carrier is moved in a direction perpendicular to the recording medium to transfer the toner image. It is also possible to apply the present invention to a transfer type image forming apparatus.

As described above, in the present embodiment, the toner image carrier 101 is formed of the insulator layer 101a and the conductor layer 101.
b, the dielectric layer 101c, the electrode head 102 is always in contact with the surface of the dielectric layer 101c, and the switch 103
As a result, the need to use a photoconductor for a toner image carrier, which has been a problem of the related art, is eliminated, and an exposure device is not required. This makes it possible to make the toner image carrier maintenance-free and to reduce the size and cost of the image forming apparatus.

(Embodiment 3) FIG. 5 is an explanatory view of a process principle for explaining a process principle of an image forming apparatus according to a third embodiment of the present invention, and FIG. 6 is an image according to a third embodiment of the present invention. FIG. 7 is a sectional view of a main part showing a periphery of a toner image carrier of the forming apparatus, and FIG. 7 is a schematic view of a main part of an image forming apparatus according to a third embodiment of the present invention.

In FIGS. 5 to 7, the toner image carrier 10
1, insulator layer 101a, conductor layer 101b, dielectric layer 1
01c, electrode head 102, transfer roller 104, refresh roller 105, bias application power supply 105a, bias application electrode 105b, sandwiching roller 106, transfer plate 10
7, toner 205a, developing roller 205b, toner image 2
05c, the recording medium 207, and the fixing device 210 are the same as those in FIGS. Reference numeral 109 denotes an electrode driving unit. As shown in FIGS. 5 to 7, the image forming apparatus according to the present embodiment is substantially the same as that of the first embodiment. As the toner image carrier 101, a conductor layer 101 b is provided on an insulator layer 101 a. The dielectric layer 101c is provided on the conductive layer 101b.
Can be biased. Further, the electrode head 102 is connected to the electrode driving unit 109 in a state where it is always grounded. However, in the present embodiment, the electrode head 10
2 has a certain distance from the surface of the dielectric layer 101c, has a mechanism for selectively contacting the dielectric layer 101c, and has a configuration in which the electrode head 101 can be selectively grounded. Different from the first embodiment. In the toner image carrier 101, a conductor layer 101b made of aluminum or the like is provided on an insulator layer 101a made of polyethylene terephthalate (PET), which is an insulator, and a dielectric layer having a thickness of about 50 μm is further formed thereon. It has a belt shape provided with a dielectric layer 101c made of a certain polyvinylidene fluoride (PVDF) or the like, and has a configuration in which a bias can be applied to the conductive layer 101b. The electrode head 102 is configured such that the number of electrodes corresponding to the resolution is always in contact with the surface of the dielectric layer 101c. The electrode head 102 may be configured by forming an electrode on a printed board by etching, or by winding an enamel wire or the like around an insulator, solidifying the resin with a resin, and then shaving and exposing the cross section of the enamel wire. it can. The electrode head 102 is always connected to the electrode driving unit 109 in a state of being grounded, and the electrode head 102 is brought into contact with the surface of the dielectric layer 101c and grounded by the operation of the electrode driving unit 109 according to print data. It has become. The electrode driving unit 109 has a configuration using an electromagnet, a piezoelectric element, or the like. In this embodiment, a description will be given of a configuration using a laminated piezoelectric element. Developing roller 2
A developing bias having the same polarity as the charging polarity of the toner 205a is applied to 05b. To the transfer roller 104, a bias having a polarity opposite to the charging polarity of the toner 205a is applied. The refresh roller 105 is made of conductive silicone rubber, urethane rubber, or a conductive brush.
The configuration is such that a high voltage can be applied.

The printing operation of the thus configured image forming apparatus will be described.

As shown in FIG. 5, the bias application electrode 10
5b through the conductive layer 1 from the bias applying power supply 105a.
A bias of -800 V is applied to 01b, and when the surface potential of the dielectric layer 101c is measured, the apparent surface potential is -800V. At this time, the voltage becomes 0 V when the applied bias is turned off. When an image forming operation is instructed by a control unit (not shown) of the image forming apparatus, the toner image carrier roller 202 is rotated, and the toner image carrier 101 is moved to an arrow A.
Start rotating in the direction. At the same time, the electrode head 102 is brought into contact with the surface of the dielectric layer 101c by the operation of the electrode driving unit 109 in accordance with the content of the image to be formed. Bias -8 applied to conductor layer 101b
The voltage is pulled to 00V, and positive charges are injected into the surface of the dielectric layer 101c. The portion where the positive charge is injected is apparently neutralized, and the surface potential becomes 0V. In addition, since -800 V appears on the surface of a place that is not grounded, an electrostatic latent image is formed on the surface of the dielectric layer 101c.

In the above steps, the toner image carrier 101
The electrostatic latent image formed above reaches the position of the developing device 205 by rotating the toner image carrier 101 in the direction of arrow A. The developing roller 205b disposed in the developing device 205 rotates and comes into contact with the toner image carrier 101. The toner 205a is thinned and adhered to the developing roller 205b, and a developing bias of about -300V is applied. As a result, the toner image carrier 101 is
The electrostatic latent image is developed by the toner 205a attached to the surface of the developing roller 205b while being moved while being nipped between the toner image carrier 101 and the nipping roller 105b.
A toner image 205c is formed thereon.

When the toner image 205c is formed on the toner image carrier 101 by the above operation, the toner image carrier 10
1 to transfer the toner image 205 c onto the recording medium 207. When the recording medium 207 is fed from a paper feeding unit (not shown) on the transfer plate 107 in the direction of arrow B, the bias of the polarity opposite to that of the toner 205 a is applied to the rear surface of the recording medium 207 by contacting the transfer roller 104. And the toner image 205 c on the toner image carrier 101 is
7 is transferred. The toner image 205c transferred onto the recording medium 207 is conveyed into the fixing device 210, and is fixed on the recording medium 207 by the action of heat, pressure, or the like, and the image forming operation is completed.

On the other hand, the toner image 2 on the toner image carrier 101
After the toner image carrier 05c is transferred onto the recording medium 207, the positive charge on the dielectric layer 101c is neutralized by bringing the toner image carrier 101 into contact with the biased refresh roller 105 to return to the original state. Return to prepare for the next image forming operation.

In the present embodiment, the parallel transfer type image forming apparatus has been described as an example. However, the orthogonal transfer is performed by moving the toner image carrier in the direction orthogonal to the recording medium. It is also possible to apply the present invention to a transfer type image forming apparatus.

As described above, in the present embodiment, the toner image carrier 101 is formed of the insulating layer 101a and the conductive layer 101.
b, the electrode head 102 is connected to the electrode driving unit 109 by using the dielectric layer 101c, which eliminates the need to use a photosensitive member for a toner image carrier, which is a problem of the related art, and eliminates the need for an exposure unit. It became. This makes it possible to make the toner image carrier maintenance-free and to reduce the size and cost of the image forming apparatus.

(Embodiment 4) FIG. 8 is a view for explaining the process principle of an image forming apparatus according to a fourth embodiment of the present invention. FIG. FIG. 7 is a cross-sectional view of a main part showing the periphery of a toner image carrier of the image forming apparatus according to the third embodiment. FIG.

In FIG. 8, the toner image carrier 101, the insulator layer 101a, the conductor layer 101b, and the dielectric layer 101
c, electrode head 102, transfer roller 104, refresh roller 105, bias application power supply 105a, bias application electrode 105b, electrode driver 109, toner 205
5A, the developing roller 205b, the toner image 205c, and the recording medium 207 are the same as those in FIG. 108 is a bias application unit.
As shown in FIGS. 6 to 8, the image forming apparatus according to the present embodiment is substantially the same as that of the first embodiment, and as a toner image carrier 101, a conductor layer 101 is formed on an insulator layer 101 a.
b, and a dielectric layer 101c is provided thereon, so that a bias can be applied to the conductive layer 101b. Also, the electrode head 102 is always
8 and is connected to the electrode driving unit 109. However, in the present embodiment, the electrode head 102 keeps a certain distance from the surface of the dielectric layer 101c, has a mechanism for selectively contacting the dielectric layer 101c, and selectively applies a bias to the electrode head 102. This embodiment is different from the second and third embodiments in that it can be connected to the unit 108. In the toner image carrier 101, a conductor layer 101b made of aluminum or the like is provided on an insulator layer 101a made of polyethylene terephthalate (PET), which is an insulator, and a dielectric layer having a thickness of about 50 μm is further formed thereon. It has a belt shape provided with a dielectric layer 101c made of a certain polyvinylidene fluoride (PVDF) or the like.
The structure is such that a bias can be applied to the conductor layer 101b. The electrode head 102 is configured such that the number of electrodes corresponding to the resolution is always in contact with the surface of the dielectric layer 101c. The electrode head 102 may be configured by forming an electrode on a printed board by etching, or by winding an enamel wire or the like around an insulator, solidifying the resin with a resin, and then shaving and exposing the cross section of the enamel wire. it can. Further, the electrode head 102 is always connected to the electrode driving unit 109 while being connected to the bias applying unit 108, and the electrode head 102 contacts the surface of the dielectric layer 101c by the operation of the electrode driving unit 109 according to the print data. , And a bias is applied. The electrode driving unit 109 has a configuration using an electromagnet, a piezoelectric element, or the like. In this embodiment, a description will be given of a configuration using a laminated piezoelectric element. A developing bias having the same polarity as the charged polarity of the toner is applied to the developing roller 205b. To the transfer roller 104, a bias having a polarity opposite to the polarity of the charged toner is applied.
The refresh roller 105 is made of conductive silicon rubber, urethane rubber, or a conductive brush, and has a configuration capable of applying a high voltage.

The printing operation of the thus configured image forming apparatus will be described.

As shown in FIG. 8, the bias application electrode 10
5b through the conductive layer 1 from the bias applying power supply 105a.
A bias of -800 V is applied to 01b, and when the surface potential of the dielectric layer 101c is measured, the apparent surface potential is -800V. At this time, the voltage becomes 0 V when the applied bias is turned off. When an image forming operation is instructed by a control unit (not shown) of the image forming apparatus, the toner image carrier roller 202 is rotated, and the toner image carrier 101 is moved to an arrow A.
Start rotating in the direction. At the same time, the electrode head 102 is brought into contact with the surface of the dielectric layer 101c by the operation of the electrode driving unit 109 in accordance with the content of the image to be formed. Therefore, positive charges are injected into the surface of the dielectric layer 101c. The portion where the positive charge is injected is apparently neutralized, and the surface potential becomes 0V.
In addition, since −800 V appears on the surface of a portion that is not connected to the bias applying unit 108, an electrostatic latent image is formed on the surface of the dielectric layer 101c.

In the above steps, the toner image carrier 101
The electrostatic latent image formed above reaches the position of the developing device 205 by rotating the toner image carrier 101 in the direction of arrow A. The developing roller 205b disposed in the developing device 205 rotates and comes into contact with the toner image carrier 101. The toner 205a is thinned and adhered to the developing roller 205b, and a developing bias of about -300V is applied. As a result, the toner image carrier 101 is
The electrostatic latent image is developed by the toner 205a attached to the surface of the developing roller 205b while being moved while being nipped between the toner image carrier 101 and the nipping roller 105b.
A toner image 205c is formed thereon.

When the toner image 205c is formed on the toner image carrier 101 by the above operation, the toner image carrier 10
1 to transfer the toner image 205 c onto the recording medium 207. When the recording medium 207 is fed from a paper feeding unit (not shown) on the transfer plate 107 in the direction of arrow B, the bias of the polarity opposite to that of the toner 205 a is applied to the rear surface of the recording medium 207 by contacting the transfer roller 104. And the toner image 205 c on the toner image carrier 101 is
7 is transferred. The toner image 205c transferred onto the recording medium 207 is conveyed into the fixing device 210, and is fixed on the recording medium 207 by the action of heat, pressure, or the like, and the image forming operation is completed.

On the other hand, the toner image 2 on the toner image carrier 101
After the toner image carrier 05c is transferred onto the recording medium 207, the positive charge on the dielectric layer 101c is neutralized by bringing the toner image carrier 101 into contact with the biased refresh roller 105 to return to the original state. Return to prepare for the next image forming operation.

In the present embodiment, the description has been given by taking the parallel transfer type image forming apparatus as an example, but the orthogonal transfer is performed by transferring the toner image by moving the toner image carrier in a direction orthogonal to the recording medium. It is also possible to apply the present invention to a transfer type image forming apparatus.

As described above, in the present embodiment, the toner image carrier 101 is formed of the insulating layer 101a and the conductive layer 101.
b, the electrode head 102 is connected to the electrode driving unit 109 by using the dielectric layer 101c, which eliminates the need to use a photosensitive member for a toner image carrier, which is a problem of the related art, and eliminates the need for an exposure unit. It became. This makes it possible to make the toner image carrier maintenance-free and to reduce the size and cost of the image forming apparatus.

[0069]

As described above, according to the image forming apparatus of the first aspect of the present invention, the toner image carrier having at least one pair of the dielectric layer and the conductor layer, and the bias is applied to the conductor layer. A bias application electrode that applies a bias from an applied power source to inject a charge of a predetermined polarity into the conductive layer, and injects a charge into the surface of the dielectric layer to form an electrostatic latent image corresponding to the resolution on the toner image carrier. A dielectric material is used for the toner image carrier by having an electrode head to be formed and a disconnection means for selectively injecting a charge of a predetermined polarity and a polarity opposite to the dielectric layer via the electrode head. Therefore, it is possible to extend the life and reduce the price of the toner image carrier. Further, since an exposure device is not required, an advantageous effect that the size and the price of the apparatus can be reduced can be obtained. .

According to the image forming apparatus of the second aspect,
In the image forming apparatus according to the first aspect, since the electrode head is always in contact with the surface of the dielectric layer, an exposure unit is not required, so that the apparatus can be advantageously reduced in size and cost. The effect is obtained.

According to the image forming apparatus of the third aspect,
3. The image forming apparatus according to claim 2, wherein the disconnecting means is a switch, and the switch only grounds the electrode head by selectively grounding the electrode head. This has the advantageous effect of reducing the size and cost of the device.

According to the image forming apparatus of the fourth aspect,
3. The image forming apparatus according to claim 2, wherein the disconnection unit is a switch, and the switch selectively connects the electrode head to the bias applying unit, so that the electrode head is only connected to the bias applying unit. This eliminates the need for an exposure device, and provides an advantageous effect that the size and cost of the apparatus can be reduced.

According to the image forming apparatus of the fifth aspect,
2. The image forming apparatus according to claim 1, further comprising contact means for selectively bringing the electrode head into contact with the surface of the dielectric layer in accordance with print data, wherein the electrode head is always connected to a predetermined potential portion, so that the exposing device is Since it is unnecessary, an advantageous effect of reducing the size and cost of the device can be obtained.

According to the image forming apparatus of the sixth aspect,
In the image forming apparatus according to the fifth aspect, since the electrode head is always connected to the ground as the predetermined potential portion, an exposure unit is not required, so that the apparatus can be reduced in size and cost. The advantageous effect described above can be obtained.

According to the image forming apparatus of the seventh aspect,
6. The image forming apparatus according to claim 5, further comprising a bias applying unit serving as a predetermined potential unit for generating a bias, wherein the electrode head is always connected to the bias applying unit, so that an exposure unit is not required. This has the advantageous effect of reducing the size and cost of the device.

According to the image forming apparatus of the present invention,
2. The image forming apparatus according to claim 1, further comprising a refresh roller for applying a bias from an applied bias power supply to the surface of the dielectric layer to neutralize the charge injected into the surface of the dielectric layer. After the transfer of the image to the recording medium is completed, the charge injected to the surface of the dielectric layer can be neutralized, and the power supply for applying a bias to the conductive layer is also used as a power supply for refreshing the dielectric layer. Therefore, an advantageous effect that the size and cost of the device can be reduced can be obtained.

[Brief description of the drawings]

FIG. 1 is a process principle explanatory diagram for explaining a process principle of an image forming apparatus according to a first embodiment of the present invention;

FIG. 2 is a cross-sectional view of a main part showing a periphery of a toner image carrier of the image forming apparatus according to the present embodiment, similarly to the first embodiment;

FIG. 3 is a main part schematic diagram of the image forming apparatus according to the present embodiment, as in the case of the first embodiment;

FIG. 4 is a process principle explanatory diagram for explaining a process principle of an image forming apparatus according to a second embodiment of the present invention;

FIG. 5 is a process principle explanatory diagram for explaining a process principle of an image forming apparatus according to a third embodiment of the present invention;

FIG. 6 is a cross-sectional view of a main part showing the periphery of a toner image carrier of an image forming apparatus according to the present embodiment, similarly to the third embodiment

FIG. 7 is a schematic diagram of a main part of an image forming apparatus according to the present embodiment, similarly to the third embodiment;

FIG. 8 is a process principle explanatory diagram for explaining a process principle of an image forming apparatus according to a fourth embodiment of the present invention;

FIG. 9 is a sectional view of a main part showing a conventional image forming apparatus.

[Explanation of symbols]

 Reference Signs List 101 toner image carrier 101a insulator layer 101b conductor layer 101c dielectric layer 102 electrode head 103 switch 104 transfer roller 105 refresh roller 105a bias application power supply 105b bias application electrode 106 sandwiching roller 107 transfer plate 108 bias application unit 109 electrode drive unit 202 Toner image carrier roller 205 Developing device 205a Toner 205b Developing roller 205c Toner image 207 Recording medium 210 Fixing device

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Shinichiro Tsunematsu 1006 Kadoma Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. Terms (reference) 2C162 AE21 AE31 AE44 AE47 AE62 AE73 AE84 EA20 2H029 AA06 AB14 AC05 AD06 AE01

Claims (8)

[Claims] 1. A toner image carrier having at least a pair of a dielectric layer and a conductor layer, and a bias of a bias application power supply is applied to the conductor layer to inject a charge of a predetermined polarity into the conductor layer. A bias application electrode, an electrode head that injects electric charge into the surface of the dielectric layer to form an electrostatic latent image corresponding to the resolution on the toner image carrier, and the dielectric layer through the electrode head. An image forming apparatus comprising: a disconnection unit for selectively injecting a charge having a polarity opposite to the predetermined polarity. 2. The image forming apparatus according to claim 1, wherein said electrode head is always in contact with said dielectric layer surface. 3. The image forming apparatus according to claim 2, wherein said disconnection means is a switch, and said switch selectively grounds said electrode head. 4. The image forming apparatus according to claim 2, wherein said disconnection means is a switch, and said switch selectively connects said electrode head to a bias applying section. 5. The apparatus according to claim 1, further comprising contact means for selectively bringing said electrode head into contact with said dielectric layer surface in accordance with print data, wherein said electrode head is always connected to a predetermined potential portion. The image forming apparatus according to claim 1. 6. The electrode head according to claim 5, wherein said electrode head is always connected to ground as said predetermined potential portion.
An image forming apparatus according to claim 1. 7. The image forming apparatus according to claim 5, further comprising a bias applying section serving as the predetermined potential section for generating a bias, wherein the electrode head is always connected to the bias applying section. 8. A refresh roller for applying a bias from the applied bias power supply to the surface of the dielectric layer to neutralize electric charges injected into the surface of the dielectric layer. 2. The image forming apparatus according to 1.