JPH08146725A - Image forming device - Google Patents

Abstract

PURPOSE: To prevent toner image disturbance by temporarily fixing toner attached to a sheet of recording paper. CONSTITUTION: An image forming device 1 is equipped with, inside its main body frame 2, a toner supply mechanism 20 to which an aperture electrode body 10 is attached, a carry mechanism 30 for carrying a sheet of recording paper P, a rear electrode roller 28, a fixing mechanism 40, and a prefixing mechanism 45. It is further equipped with a sheet feed cassette CS and a sheet ejection table DT. The prefixing mechanism 45 consists of a temporary fixing roller 46 and a pressure roller 47. A toner image formed on the sheet of recording paper P is temporarily fixed by the rollers 46 and 47 and carried to the fixing mechanism 40.

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. The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus in which a hypothetical fixing process is performed prior to a toner fixing process.

[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]

In the image forming apparatus disclosed in Japanese Patent Application Laid-Open No. 6-79907 proposed by the applicant of the present application, the carrying roller is not provided in the carrying path corresponding to the aperture electrode body. Since the recording paper is conveyed while holding both left and right end portions parallel to the conveyance direction, the central portion of the recording paper which is not held hangs downward, and a recording mechanism such as a toner case is conveyed during the conveyance. May come into contact with the member of
There is a problem that the toner image attached to the recording paper is disturbed or partially missing, and the quality of the image on the recording paper deteriorates.

It is an object of the present invention to form a beautiful image without disturbing the toner image by tentatively attaching the toner that has passed through the opening and adhered to the recording paper earlier than the fixing process. An image forming apparatus is provided.

[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 provided with a fixing mechanism for fixing, a conveyance path is provided in the conveyance path on the downstream side of the opening in the conveyance direction and on the upstream side of the fixing mechanism in the vicinity of the conveyance path. And those having a front fixing means for pressing to provisionally fixed on the recording medium the toner adhering to the recording medium.

Here, in the image forming apparatus of claim 2, in the invention of claim 1, the pre-stage fixing means sandwiches the recording medium conveyed along the conveying path while applying a predetermined pressing force. And a pair of roller members at least one of which is rotationally driven. Further, in the image forming apparatus of claim 3, in the invention of claim 2, among the pair of roller members of the pre-stage fixing means, at least the surface of the roller member which comes into contact with the toner adhering to the recording medium has And an anti-adhesion layer for preventing the adhesion of

[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, since a pre-stage fixing unit is provided in the vicinity of the conveying route on the downstream side of the opening in the conveying direction and on the upstream side of the fixing mechanism, the pre-stage fixing unit adheres to the recording medium. The toner is tentatively pressed against the recording medium. After that, the fixing mechanism fixes the toner, which is supposedly attached to the recording medium, to the recording medium by heating.

As described above, the toner that has passed through the opening and adhered to the recording medium is presumed to be attached to the recording medium earlier than the fixing process by the fixing mechanism. The adhesiveness of the
Even if the recording medium hangs down and contacts the members of the recording mechanism such as the aperture electrode body and the toner case, the toner image assumed on the recording medium is disturbed or partially missing. It is possible to form a beautiful image.

According to another aspect of the image forming apparatus of the present invention, the pre-stage fixing means are arranged in a facing manner so as to sandwich the recording medium conveyed along the conveying path while applying a predetermined pressing force. Since at least one of the pair of roller members is rotatably driven, the toner adhered to the recording medium is pressed by the pressing force of the pair of roller members to strengthen the adhesive force. As a result, the recording medium is conveyed by the rotational drive of one roller member, and the recording medium does not hang down, and a beautiful image can be formed.

According to another aspect of the image forming apparatus of the present invention, the toner is prevented from adhering to at least the surface of the roller member of the pair of roller members of the pre-stage fixing means which is in contact with the toner adhering to the recording medium. Since the adhesion preventing layer is formed, the toner adhered to the recording medium can be reliably and hypothetically adhered without being peeled off by the roller member in contact with the toner.

[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 transport mechanism 30 that transports the recording paper P.
The back electrode roller 28, the fixing mechanism 40, and the pre-stage fixing mechanism 45 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, and on the rear side of the main body frame 2, a paper discharge table that stores the recorded and discharged recording papers P. DT is provided.

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 transport roller 23, the toner T is rubbed by the rollers 22 and 23 and is negatively charged. However, this toner conveying roller 23
An insulating coating layer made of an insulating material may be formed on the surface of the.

On the other hand, one end 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 supply roller is provided. The toner regulating blade 24 regulates the amount of the toner T, which is supplied by 22 and adheres to the surface of the toner conveying roller 23, 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.

Next, the transport mechanism 30 will be described with reference to FIG. Guide plates 31 to 34 are sequentially provided between the paper feed cassette CS and the paper discharge table DT, guided by these guide plates 31 to 34, and discharged from the paper feed cassette CS through the vicinity of the upper side of the aperture electrode body 10. A transport path D reaching the paper table DT is formed. A pair of transport rollers 35 to 36 is rotatably provided on the upstream side of the transport path D, and a fixing mechanism 40 is provided on the most downstream side of the transport roller D in proximity to the transport path D. A pre-stage fixing mechanism 45 is provided close to the conveyance path D on the upstream side of the fixing mechanism 40 in the conveyance direction and on the downstream side of the opening 11.

A back electrode roller 28 is disposed immediately above the aperture electrode body 10 and is rotatably supported by the main body frame 2. The recording paper P stored in the paper feed cassette CS is The sheet is conveyed by these conveying rollers 35 to 36, is in contact with the lower portion of the back electrode roller 28, passes through the vicinity of the upper side of the aperture electrode body 10, further passes through the fixing mechanism 40 and the pre-stage fixing mechanism 45, and is discharged along the conveying path D. It is conveyed in the conveyance direction F to the paper table DT. 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.

The fixing mechanism 40 is composed of a fixing heating roller 41 having a halogen lamp built therein and a pressing roller 42 for pressing it. The pre-stage fixing mechanism 45 is a hypothetical wearing roller 46 and a pressing roller for pressing it. And 47. The hypothetical wearing roller 46 and the pressing roller 47 are provided in a close proximity to each other so as to sandwich the conveyed recording paper P while applying a predetermined pressing force. Further, on the surface of the hypothetical wearing roller 46, an adhesion preventing layer 46a made of a fluororesin such as Teflon coat and having excellent heat resistance is formed, and the adhesion of the toner T on the recording paper P is prevented at the time of hypothetical wearing. ing.

Then, the back electrode roller 28, the carrying roller 35, the hypothetical wearing roller 46, and the fixing heating roller 4 are used.
1 is driven by a drive motor via a transport drive mechanism (not shown), and the transport drive is controlled by a control unit 50 described later so that the transport speed becomes a predetermined transport speed.

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 drive 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 drive 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 negatively charged toner T receives an electrostatic force in the direction of high potential, passes through the opening 11 from the surface of the toner transport roller 23 and is attracted to the control electrode 12, and at the same time, the rear electrode roller 2
By the high voltage applied to the back electrode roller 28, the electrostatic force due to the electric field generated between the back electrode roller 28 and the control electrode 12 passes through the opening 11 and is attracted to the back electrode roller 28, that is, the recording paper P. Be attached and adhere. However, when a voltage of −30 V is applied to the control electrode 12, the toner T on the surface of the toner transport roller 23 passes through the opening 11 due to the electric field from the toner transport roller 23 to the control electrode 12, contrary to the above. There is nothing to do.

Next, the operation of forming a toner image on the recording paper P conveyed along the conveyance path D by the image forming apparatus 1 and the assumed adhesion operation will be described. When the recording paper P fed from the paper feed cassette CS is transported in the transport direction F along the transport path D to a predetermined recording start position, the control unit 50 receives an image received from an external device (not shown). A drive signal is output to the drive circuit 51 based on the signal. When a drive voltage of +30 V is applied from the drive circuit 51 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 transport roller 23 receives an electrostatic force in the direction of higher potential, and the opening 11 is opened from the surface of the toner transport roller 23.
And is attracted to the control electrode 12.

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, the toner T is collectively adhered in layers on the adhered surface of the recording paper P. afterwards,
The toner T attached to the recording paper P is, as shown in FIG.
By the pre-stage fixing mechanism 45, the assumed wearing roller 46 and the pressing roller 47 are pressed so as to be sandwiched while applying a predetermined pressing force to change the toner Ta into a crushed state, and the toner Ta is attached to each other. The adhesion is strengthened and the adhesion of the toner Ta to the recording paper P is strengthened.

Then, the toner Ta that has been assumedly attached on the recording paper P is then transferred to the fixing heating roller 4 of the fixing mechanism 40.
By 1, the fixing process by heating is performed and the sheet is discharged to the sheet discharge table DT. In this way, the toner T that has passed through the opening 11 and adhered to the recording paper P is presumably attached to the recording paper P by the pre-stage fixing mechanism 45 at a time earlier than the fixing process by the fixing mechanism 40. Since the adhesive force of the toner T and the adhesive force of the toner T to the recording paper P are strengthened, and the recording paper P is hung down by the hypothetical wearing roller 46 and the pressing roller 47, the recording paper P hangs down to the toner case. It is possible to form a beautiful image without causing the toner image to be disturbed or partly dropped by coming into contact with a member of the recording mechanism such as 21.

The recording paper P is, for example, the toner case 2
Toner T on recording paper P even when it comes into contact with
Since the adhesive force is enhanced, the toner image is not disturbed, and a similarly beautiful image can be formed. Further, since the adhesion preventing layer 46a made of fluororesin having excellent heat resistance is formed on the surface of the hypothetical wear roller 46, the toner T adhered to the recording paper P is not peeled off, and the toner T is not peeled off. You can certainly wear it without any problems.

The front-stage fixing mechanism 45 has the opening 11
It may be provided so as to be closest to the opening 11 on the downstream side in the transport direction. It should be noted that various modifications may be made based on existing technology and technology obvious to those skilled in the art within the scope of the technical idea of the present invention. 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.

[0029]

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. The toner is attached to the recording medium after passing through the opening, and the toner is attached to the recording medium earlier than the fixing process by the fixing mechanism.
Even if the recording medium hangs downward and comes into contact with the members of the recording mechanism, it is assumed that the toner adheres to the recording medium and the adhesive force between the toner and the toner adheres to the recording medium. It is possible to form a beautiful image without disturbing or partially missing the toner image supposedly attached to the medium.

According to the image forming apparatus of the second aspect, the pre-stage fixing means are arranged in a close proximity to each other so as to sandwich the recording medium conveyed along the conveying path while applying a predetermined pressing force. Since at least one of the pair of roller members is rotatably driven, the toner attached to the recording medium is pressed by the pressing force of the pair of roller members to strengthen the adhesive force. In addition, the recording medium is conveyed while being supported by the pair of roller members via the rotation drive of one roller member, and the recording medium does not hang down, and a clean image can be formed. .

According to the image forming apparatus of the third aspect, of the pair of roller members of the pre-stage fixing means, the toner is prevented from adhering to at least the surface of the roller member which is in contact with the toner adhering to the recording medium. Since the adhesion preventing layer is formed, the toner adhering to the recording medium can be reliably and hypothetically adhered to the recording medium without being peeled off by the roller member in contact with the toner.

[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.

FIG. 4 is an enlarged partial side view of a main part of FIG. 1, showing a pre-stage fixing mechanism and a fixing mechanism.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image forming apparatus 10 Aperture electrode body 11 Opening 12 Control electrode 20 Toner supply mechanism 35 Heating roller 40 Fixing mechanism 41 Fixing heating roller 45 Pre-stage fixing mechanism 46 Assumed wear roller 46a Adhesion prevention layer 47 Pressing roller 50 Control unit 51 Drive Circuit D Transport path E1 Power supply circuit E2 Power supply circuit P Recording paper T Toner

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 transport path, the transport path is provided downstream of the opening in the transport direction and upstream of the fixing mechanism in proximity to the transport path, and adheres to the recording medium. Image forming apparatus characterized by comprising a front fixing means for pressing to provisionally fixed to the recording medium a toner. 2. The pre-stage fixing unit is arranged in a facing manner so as to sandwich a recording medium conveyed along a conveying path while applying a predetermined pressing force, and at least one of them is rotationally driven. The image forming apparatus according to claim 1, comprising a pair of roller members. 3. An adhesion prevention layer for preventing adhesion of toner is formed on at least the surface of the roller member of the pair of roller members of said pre-stage fixing means, which is in contact with the toner adhered to the recording medium. The image forming apparatus according to claim 2, wherein: