JPH08137216A - Image forming device - Google Patents

Abstract

PURPOSE: To provide an image forming device which securely carries a recording medium with a toner image formed on it. CONSTITUTION: Inside the main body frame 2 of the image recorder 1 is provided with a toner supply mechanism 20 with an aperture electrode body attached to it, a medium carrying/driving mechanism 30 composed of a medium carry belt 31 for carrying recording paper P, a back electrode roller 28, a heating roller 42, a pressure roller 43, and a brush roller 38. The recording paper P with a toner image formed on it is carried to the heating roller 42 by means of the medium carry belt 31 electrified by the brush roller 38, and the image is fixed by heat.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention controls a voltage applied to an electrode array having a plurality of openings formed in an aperture electrode body to fix toner adhering to a recording medium passing through the openings. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus, and more particularly, to an apparatus in which a recording medium having toner adhered to a medium conveyance belt is conveyed until it is fixed.

[0002]

2. Description of the Related Art Conventionally, an aperture electrode body having a large number of openings (apertures) is provided, and the driving voltage supplied to the electrodes provided in the openings is controlled so that the toner passing through the openings is used as a recording medium. Various image forming apparatuses have been proposed which are attached and recorded. For example, JP-A-6-7990
In Japanese Patent Publication No. 7, a large number of minute openings (apertures) are formed in rows in the width direction of the recording medium at minute intervals, and control electrodes are provided around each of the large numbers of openings. An aperture electrode body is provided, and a toner supply mechanism is provided on one side of the aperture electrode body, the toner supply mechanism having a toner feeding roller that rotates and supplies toner while pressing the toner against a large number of openings of the aperture electrode body, and the other side. A counter electrode to which a high voltage is applied, and while individually controlling the drive voltage supplied to each control electrode of this aperture electrode body,
By transporting the recording medium along the counter electrode, the toner supplied from the toner supply mechanism passes through the opening and is ejected toward the counter electrode by the electrostatic attraction force of the counter electrode. An image forming apparatus has been proposed in which an image is recorded by being attached to a recording sheet and then fixed by a fixing mechanism.

In this image forming apparatus, a plurality of toners located in the respective openings are attracted to and adhered to the recording paper through electrostatic force generated by the respective control electrodes of the electrode array provided in the aperture electrode body, so that a plurality of toners are attached. The gap between the opening and the counter electrode facing the opening is set to about 1 mm. That is, the recording sheet can be conveyed by the conveying roller in the conveying path other than the one corresponding to the aperture electrode body, but the conveying roller cannot be provided in the conveying path corresponding to the aperture electrode body. Is transported while holding both left and right ends parallel to the transport direction, and is heated while applying a pressing force by a fixing heating roller provided on the downstream side in the transport direction with respect to the aperture electrode body. Is fixed to the recording paper.

[0004]

However, in the image forming apparatus disclosed in Japanese Patent Laid-Open No. 6-79907 proposed by the applicant of the present application, a conveying roller is provided in the conveying path corresponding to the aperture electrode body. Since the recording paper is conveyed while holding the left and right ends that are parallel to the conveyance direction, the central portion of the recording paper that is not held hangs downward, and the aperture electrode body or It may come in contact with a member of a recording mechanism such as a toner case. In such a case, the toner image attached to the recording paper is disturbed or partially missing, and the quality of the image on the recording paper is deteriorated. There was a problem.

An object of the present invention is to provide an image forming apparatus capable of forming a beautiful image without disturbing the toner image by conveying the recording medium having the toner image formed thereon by a medium conveying belt. is there.

[0006]

According to a first aspect of the present invention, there is provided an image forming apparatus comprising a plurality of openings formed in a row in a horizontal direction orthogonal to a conveying direction of a recording medium and control electrodes provided in the plurality of openings, respectively. Aperture electrode body having an electrode array, a toner supply mechanism for supplying toner to the openings of the aperture electrode body, and a drive voltage supplied to each control electrode of the electrode array are individually controlled to pass through each opening. The toner control means for controlling the toner to be used, the conveyance path for conveying the recording medium through the vicinity of the aperture electrode body on the side opposite to the toner supply mechanism with respect to the aperture electrode body, and the toner attached to the recording medium to the recording medium. In an image forming apparatus having a fixing mechanism for fixing, a dielectric member stretched so as to face a conveyance path from a position corresponding to at least an opening of the conveyance path to the fixing mechanism. A flexible medium conveying belt, which is arranged on the side opposite to the aperture electrode body with respect to the recording medium conveyed in the conveying path, and is driven in the recording medium conveying direction, In order to attract the recording medium to the belt by electrostatic force, the medium carrying belt is provided with static electricity generating means for charging static electricity.

The image forming apparatus according to a second aspect of the present invention is the image forming apparatus according to the first aspect of the present invention, further including drive means for driving the medium transport belt in synchronization with the transport speed of the recording medium. According to a third aspect of the present invention, in the first or second aspect of the invention, the static electricity generating unit generates static electricity having a polarity different from that of the static electricity charged on the toner.

[0008]

In the image forming apparatus according to the present invention, the toner is supplied to the opening of the aperture electrode body by the toner supply mechanism, and the control electrode is provided in each of the plurality of openings formed in the aperture electrode body. The toner control means individually controls the drive voltage to be supplied to the electrode array, so that the toner supplied by the toner supply means passes through the openings and is transferred to the recording medium conveyed along the conveying path. Adhere to. By the way, the flexible medium conveyance belt made of a dielectric material is provided on the recording medium conveyed along the conveyance path so as to face the conveyance path from the position corresponding to at least the opening to the fixing mechanism in the conveyance path. The static electricity generating means is arranged so as to be stretched on the side opposite to the aperture electrode body, and the medium carrying belt charges the medium carrying belt with static electricity. Therefore, the recording medium is charged on the medium carrying belt from a position corresponding to the opening in the middle of carrying. It is attracted by electrostatic force. Then, the recording medium to which the toner image is attached is conveyed to the fixing mechanism while being attracted to the medium conveyance belt by the conveyance drive of the medium conveyance belt in the recording medium conveyance direction, and the toner image on the recording medium is heated to the recording medium. It is fixed.

As described above, the medium conveying belt is provided in a stretched state facing at least the conveying path from the position corresponding to the opening to the fixing mechanism, is driven to be conveyed, and is charged with static electricity. By controlling the drive voltage supplied to the electrode array provided in the plurality of openings, the toner image is attached to the recording medium, and the recording medium with the toner image attached extends from the position of the opening to the fixing mechanism. Then, the entire upper surface is attracted and stretched by the electrostatic force charged on the medium carrying belt, and the recording medium is carried to the fixing mechanism and fixed, so that the recording medium hangs downward and the aperture electrode body or It is possible to form a beautiful image without contacting a member of the recording mechanism such as a toner case with the toner image adhered to the recording medium and causing the toner image to be partially omitted.

According to another aspect of the image forming apparatus of the present invention, since the medium conveying belt is provided with driving means for conveying the medium in synchronization with the conveying speed of the recording medium, the recording medium to which the toner image is attached is the medium conveying belt. The toner image is conveyed to a fixing mechanism at a predetermined conveying speed while being adhered to the toner, and the toner image can be conveyed without being disturbed and a stable fixing process can be performed.

In the image forming apparatus according to the third aspect, the static electricity generating means generates static electricity having a polarity different from that of the static electricity charged on the toner, so that the static electricity having a polarity different from the polarity of the toner is transferred to the medium carrying belt. The toner that has been charged and has passed through the openings in accordance with the drive voltage supplied to each control electrode of the electrode array is attracted to the medium carrying belt, and the toner image is reliably attached to the recording medium.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. In this embodiment, the movement of the toner supplied from the toner supply mechanism is controlled by an aperture electrode body to apply the present invention to an image forming apparatus for recording an image on a recording sheet. As shown in FIG. 1, the image forming apparatus 1 includes
Inside the main body frame 2, the aperture electrode body 10, the toner supply mechanism 20, and the medium conveyance drive mechanism 30 that adsorbs the recording paper P to the medium conveyance belt 31 and conveys it in the conveyance direction F.
The back electrode roller 28 and the fixing mechanism are basically provided. Here, on the front side of the main body frame 2, there is provided a paper feed cassette CS that stores a large number of recording papers P,
Further, on the rear side of the main body frame 2, there is provided a discharge table DT for storing the recorded and discharged recording paper P, and further on the downstream side in the transport direction, there are a fixing heating roller 42 having a halogen lamp built therein and this. And a pressing roller 43 that presses against. Here, these fixing heating rollers 42
And the pressing roller 43 form a fixing mechanism.

First, the toner supply mechanism 20 will be described. In the toner case 21 having a width dimension substantially the same as the width of the recording paper P, the electrically insulating toner T having an electrical insulation property is accommodated and the left and right sides are stored. A toner supply roller 22 and a toner transport roller 23 extending in the direction are rotatably supported respectively. The toner carrying roller 23 is formed by attaching a nickel sleeve to the outer circumference of the sponge roller body, and the toner supplying roller 22 and the toner carrying roller 23 are rotationally driven by a roller driving mechanism (not shown). .

Here, when the toner T is supplied from the toner supply roller 22 to the toner conveying roller 23, the toner T
Is rubbed by both rollers 22 and 23 and charged to the negative electrode. However, an insulating coating layer made of an insulating material may be formed on the surface of the toner conveying roller 23.

By the way, one end portion of a toner regulating blade 24 having a thin plate-like elasticity is attached to the toner case 21, and its curved portion is in pressing contact with the toner conveying roller 23, and the toner supplying roller The toner regulating blade 24 regulates the amount of the toner T supplied by 22 and adhering to the surface of the toner conveying roller 23 and its charge amount to a predetermined amount.

At the upper end of the toner case 21, an aperture electrode body 10 which is tilted in a substantially roof shape is attached so as to cover the toner case 21 and contact the upper end of the toner conveying roller 23 from above. Has been. As shown in FIGS. 1 to 3, the aperture electrode body 10 is formed on a heat-resistant base substrate made of a polyimide resin film having an insulating property and a thickness of about 25 μm at a position approximately at the center in the front-rear direction. , In the left-right direction (corresponding to the horizontal direction orthogonal to the transport direction), the circular openings (apertures) 11 having a diameter of about 60 to 65 μm are arranged at intervals of about 127 μm, for example, in the case of a print width of A4 paper. About 1700 pieces are formed in one row.

Further, an annular control electrode 12 made of a metal foil is attached to the upper surface of the outer periphery of each of the plurality of openings 11, and a thin conductive wire 1 extending from each control electrode 12 is provided.
3 are attached to the base substrate, respectively. And
As shown in FIG. 3, each of these many conductors 13 has
The drive voltage of +30 V or −30 V according to the image data is individually supplied by the drive circuit 51 via the control line L. Here, an electrode array is configured by a large number of control electrodes 12 arranged in a row.

Next, the medium transport drive mechanism 30 will be described with reference to FIGS. Immediately downstream of the paper feed cassette CS, they are provided to face each other and press each other 1
A pair of conveying rollers 40 and 41 are rotatably supported by the main body frame 2, and three support rollers 32, 33, and 34 are rotatably supported by the main body frame 2 so as to surround the back electrode roller 28. Has been done. The fixing heating roller 42 and the transport roller 40 are driven by a drive motor via a drive mechanism (not shown), and the rotational drive thereof is controlled by a control unit 50 described later so as to have a predetermined transport speed. It

On the other hand, a flexible dielectric medium transport belt 31 made of a polyimide resin film having a width dimension substantially the same as the width of the recording paper P has a transport roller 41, a pressing roller 43, and three support rollers. It is stretched over 32, 33, and 34, and is driven to be driven in a predetermined rotation direction indicated by an arrow in FIG. 1 by rotational driving of the fixing heating roller 42 and the transportation roller 40. That is, the sheet discharge cassette D passes from the sheet feed cassette CS through the vicinity of the upper side of the aperture electrode body 10
A transport path D for transporting the recording paper P is formed up to T, and a medium transport section of the medium transport belt 31 corresponding to the transport roller 40 to the fixing heating roller 42 is transported through the transport path D. The sheet P is positioned on the opposite side of the aperture electrode body 10 with respect to the sheet P, is stretched so as to face the transport path D, and is transported in the transport direction F.

Then, in the vicinity of the support roller 34,
A brush roller (corresponding to static electricity generating means) 38 that is long in the left-right direction is disposed so as to be rotatably supported by the main body frame 2 and contactable over the entire width of the medium carrying belt 31, and the brush roller 38 is The medium transport belt 31 is rotationally driven by a drive mechanism (not shown) so that the rotational direction is opposite to the moving direction of the medium transport belt 31. That is, when the brush roller 38 that rotates at a high speed comes into rotational contact with the medium conveying belt 31 that is driven to be conveyed, the outer peripheral surface of the medium conveying belt 31 has a polarity different from that of the negative electrode charged by the toner T due to friction. The static electricity of the positive electrode is charged. That is, the medium transport belt 3
Since 1 is driven to be conveyed in a predetermined rotation direction, the static electricity of the positive electrode is charged over the entire outer peripheral surface of the medium conveying belt 31.

A rear electrode roller 28 is provided immediately above the aperture electrode body 10 and is rotatably supported by the main body frame 2 so that the recording paper P fed from the paper feed cassette CS is In a state where the entire upper surface of the positive electrode is attracted to the medium carrying belt 31 where the static electricity of the positive electrode is charged by electrostatic force, the medium is conveyed to the lower part of the rear electrode roller 28 and near the upper side of the aperture electrode body 10 and further fixed. The sheet is conveyed in the conveying direction F along the conveying path D to the discharge table DT via the heating roller 42 for use. Here, since the toner T passes through the opening 11 and adheres to the recording paper P due to the electrostatic force generated by the control electrode 12, the recording paper P is exposed to the aperture electrode body in the transport path portion corresponding to the opening 11. 10 is conveyed in a narrow gap of about 1 mm.

Next, the control system for image recording of the image forming apparatus 1 will be briefly described with reference to FIG. 3. A high voltage of about +1 KV is always applied to the back electrode roller 28 by the power supply circuit E1. The negatively charged toner T is applied to the rear electrode roller 28 with a large electrostatic force.
It is designed to attract to.

On the other hand, a driving circuit 51 is connected to the conducting wire 13 of the aperture electrode body 10 via a control line L composed of a plurality of signal lines, and the driving circuit 51 has + 30V and −30V.
A power supply circuit E2 that outputs two types of drive voltages of 30V,
A control unit 50 including a microcomputer is connected to the control unit 50. Then, the control unit 50 outputs a drive signal corresponding to the image signal to the drive circuit 51.
Therefore, the drive circuit 51 switches the drive voltage of +30 V or −30 V in accordance with the drive signal and supplies it individually to each conductor 13 via the control line L. The control unit 50 is also connected to a device such as an external computer or communication device (not shown) that sends out image signals. Further, the toner conveying roller 2
3 is always grounded.

As a result, the drive circuit 51 causes +30
When the drive voltage of V is applied to the conductor 13, that is, the control electrode 12, an electric field from the control electrode 12 to the toner carrying roller 23 is generated due to the potential difference between the control electrode 12 and the toner carrying roller 23. The toner T charged on the negative electrode receives an electrostatic force in the direction of high potential,
At the same time as the toner transport roller 23 is attracted to the control electrode 12 through the opening 11 from the surface of the toner transport roller 23, the high voltage applied to the back electrode roller 28 causes the back electrode roller 28 to move.
Through the opening 11 through the electrostatic force due to the electric field generated between the rear electrode roller 28 and the control electrode 12,
That is, the recording paper P that is conveyed while being attracted to the medium conveyance belt 31 is attracted and attached.

At this time, since the medium carrying belt 31 is charged with the static electricity of the positive electrode, the attracting force of the toner T charged on the negative electrode is increased, and the toner T is surely attached to the recording paper P. To do. However, the control electrode 1
When a voltage of -30 V is applied to the toner 2, the toner T on the surface of the toner carrying roller 23 is reversely formed by the electric field from the toner carrying roller 23 to the control electrode 12 contrary to the above.
It does not pass through the opening 11. Here, since a gap of about 1 mm is provided between the medium transport belt 31 and the opening 11, the toner T is not attracted by the static electricity charged on the medium transport belt 31.

Next, the operation of forming a toner image on the recording sheet P by the image forming apparatus 1 while conveying the recording sheet P conveyed along the conveying path D in the conveying direction F will be described. Prior to the image forming process, the brush roller 3
8 is driven to rotate at high speed, and the fixing heating roller 4
Since 2 and the conveyance roller 40 are rotationally driven, the electrostatic charge of the plus electrode is charged along the entire outer peripheral surface of the medium conveyance belt 31 as the medium conveyance belt 31 is conveyed.

Then, the recording paper P fed from the paper feed cassette CS is electrostatically attracted to the medium conveying belt 31 having the plus electrode electrostatically charged, and the entire upper surface thereof is attracted by the back electrode roller 28. When the control unit 50 is conveyed in the conveyance direction F along the conveyance path D to a predetermined recording start position near the lower side, the control unit 50 controls the drive circuit 51 based on an image signal received from an external device (not shown). Output drive signal. And from the drive circuit 51 + 30V
Is applied to the control electrode 12, an electric field is generated from the control electrode 12 toward the toner carrying roller 23. Due to this electric field, the negatively charged toner T on the surface of the toner carrying roller 23 is An electrostatic force is applied in the direction of high potential, and the toner is attracted to the control electrode 12 from the surface of the toner transport roller 23 through the opening 11.

Further, a high voltage (about +1 KV) applied to the back electrode roller 28 causes an electrostatic force due to an electric field generated between the back electrode roller 28 and the control electrode 12,
The toner T that has passed through the opening 11 is transferred to the back electrode roller 2
8, that is, the recording paper P is attracted and jumps out and adheres to the surface thereof. At this time, since the medium carrying belt 31 is charged with the static electricity of the positive electrode, the attracting force of the toner T charged on the negative electrode is increased, and the toner T is surely attached to the recording paper P. Thereafter, the recording paper P on which the toner T is attached is conveyed to the conveyance path D in the conveyance direction F in a state where the entire surface thereof is attracted to the medium conveyance belt 31 by electrostatic force, and is heated by the fixing heating roller 42. The fixing process is performed and the sheet is discharged to the sheet discharge table DT.

As described above, since the medium carrying belt 31 is carried in the carrying direction F in the medium carrying section and is charged with the static electricity of the plus electrode, the plurality of openings 1 are formed.
The toner image is attached to the recording sheet P by controlling the drive voltage supplied to the control electrode 12 provided on the recording sheet P. The recording sheet P with the toner image attached thereto is electrostatically charged on the medium conveying belt 31 to generate the toner image. Since the entire surface is adsorbed and stretched, the recording paper P is conveyed to the fixing heating roller 41 and subjected to the fixing process, so that the recording paper P hangs downward, and the recording mechanism such as the aperture electrode body 10 and the toner case 21. The toner image adhered to the recording paper P is not disturbed or partly dropped by contact with the member (1), and a beautiful image can be formed.

Further, the brush roller 38 is driven to rotate at a high speed, and due to friction with the medium conveying belt 31, static electricity of a negative electrode charged with the toner T and a positive electrode having a different polarity is formed on the surface of the medium conveying belt 31. Is charged, the toner T charged on the negative electrode is
The electrostatic force generated by the medium carrying belt 31 is added to the electrostatic force generated by 8, and the recording medium P is reliably attached to the recording paper P by a larger attraction force.

Instead of the brush roller 38, various static electricity generating devices in the shape of a rod extending in the width direction of the recording paper P may be provided, or the medium carrying section of the medium carrying belt 31 may be fixed from the opening 11. Within the scope of the technical concept of the present invention, for example, the medium conveying belt 31 is provided only on the conveying path portion to the heating roller 42, or the medium conveying belt 31 is made of various dielectric and flexible materials. Various modifications may be made based on existing technology or technology obvious to those skilled in the art. It is needless to say that the present invention can be applied to various image forming apparatuses in which the adhesion of the toner T to the recording paper P is controlled by the aperture electrode body 10.

[0032]

According to the image forming apparatus of the first aspect, the recording medium is conveyed through the aperture electrode body having the opening and the electrode array, the toner supply mechanism, the toner control means, and the vicinity of the aperture electrode body. A medium conveyance belt that includes a conveyance path and a fixing mechanism that fixes the toner, and is provided in a stretched state facing at least the conveyance path from the position corresponding to the opening to the fixing mechanism, and the medium conveyance belt. A static electricity generating unit for charging static electricity is provided on the medium transport belt, and the medium transport belt is transported and driven in the transport direction of the recording medium. Moreover, since the static electricity is charged, the drive voltage supplied to the electrode array provided in the plurality of openings is applied. By controlling, the toner image is attached to the recording medium, and the recording medium on which the toner image is attached is electrified to the medium conveyance belt from the position of the opening to the fixing mechanism. The entire upper surface of the recording medium is attracted by the electrostatic force and is stretched, and is conveyed to the fixing mechanism for fixing processing, so that the recording medium hangs downward, and members of the recording mechanism such as the aperture electrode body and the toner case. In contact with
It is possible to form a beautiful image without disturbing or partially missing the toner image attached to the recording medium.

According to the image forming apparatus of the second aspect, the driving means for driving the medium carrying belt in synchronism with the carrying speed of the recording medium is provided. While being attached to the belt, the toner image is conveyed to a fixing mechanism at a predetermined conveying speed, and the toner image can be conveyed without being disturbed and a stable fixing process can be performed.

According to the image forming apparatus of the third aspect, the static electricity generating means generates static electricity having a polarity different from that of the static electricity charged on the toner. The toner having passed through the openings according to the driving voltage supplied to each control electrode of the electrode array is attracted to the medium carrying belt, and the toner image surely adheres to the recording medium. .

[Brief description of drawings]

FIG. 1 is a schematic side view illustrating an internal mechanism of an image forming apparatus.

FIG. 2 is a partially enlarged perspective view of an aperture electrode body.

FIG. 3 is an enlarged partial side view of an essential part of FIG. 1 for explaining the adhesion of toner to recording paper.

[Explanation of symbols]

 1 Image Forming Apparatus 10 Aperture Electrode Body 11 Opening 12 Control Electrode 20 Toner Supply Mechanism 30 Medium Transport Drive Mechanism 31 Medium Transport Belt 38 Brush Roller 42 Fixing Heating Roller 50 Control Unit 51 Drive Circuit D Transport Path E1 Power Supply Circuit E2 Power Supply Circuit P Recording paper T Toner

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication G03G 15/00 510

Claims (3)

[Claims] 1. An aperture electrode body having a plurality of openings formed in a row in a horizontal direction orthogonal to a recording medium conveyance direction and an electrode array including control electrodes provided in the plurality of openings, and an aperture electrode thereof. A toner supply mechanism that supplies toner to the openings of the body, a toner control unit that individually controls the drive voltage supplied to each control electrode of the electrode array to control the toner that passes through each opening, and the aperture. An image forming apparatus provided with a transport path for transporting a recording medium through the vicinity of the aperture electrode body on the side opposite to the toner supply mechanism with respect to the electrode body, and a fixing mechanism for fixing the toner adhering to the recording medium onto the recording medium. In the conveyance path, a flexible medium conveyance bell made of a dielectric material is stretched so as to face the conveyance path from the position corresponding to at least the opening to the fixing mechanism. And a medium conveying belt which is disposed on the side opposite to the aperture electrode body with respect to the recording medium conveyed in the conveying path and is driven to be conveyed in the recording medium conveying direction; An image forming apparatus comprising: a static electricity generating unit that charges the medium carrying belt with static electricity so as to attract the medium with electric power. 2. The image forming apparatus according to claim 1, further comprising drive means for driving the medium transport belt in synchronism with a transport speed of a recording medium. 3. The image forming apparatus according to claim 1, wherein the static electricity generating unit generates static electricity having a polarity different from that of the static electricity charged on the toner.