JPH10250891A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize recording material conveyance of high accuracy without applying extra load at the time of conveying recording material by providing a carrier path with a carrier guide formed of conductive material so as to guide the conveyed recording material in sliding contact. SOLUTION: U-shape carrier guides 9a, 9b are conveying means for picked-up recording paper S and are provided to guide the recording paper S to a pair of carrier rollers 10. The carrier guides 9a, 9b and an image forming means have such position relation that the recording paper S can be stretched over them. The carrier guide 9b provided on the inner peripheral side of a carrier path is formed of conductive resin material (surface resistance 10<6> Ω, for instance) such as conductive plastic and electrically earthed through a copper wire. The recording paper S is conveyed while coming in frictional contact with the carrier guide 9b, but since the carrier guide 9b is formed of conductive material, the accumulation of static electricity is small, and the increase of back tension caused by static electricity is extremely small.

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 having a conveyance guide in a conveyance path.

[0002]

2. Description of the Related Art Conventionally, as an image forming apparatus of this type, a recording paper housed in a cassette is picked up by a feed roller, and is conveyed to a nip between a photosensitive drum as an image forming means and a transfer roller. After image formation, the sheet is generally conveyed and discharged to a sheet discharge tray.

In such an apparatus, the recording paper is generally conveyed to an image forming means or the like and several conveying means one after another, and the recording paper is transferred between the conveying means. A conveyance guide for guiding the next conveyance means is provided.

As an example, FIG. 7 shows a conveyance guide provided between a feeding means and an image forming means. FIG. 7 is a schematic configuration diagram in which the conveyance path from when the recording paper is fed to when it is conveyed to the image forming unit is enlarged.

In the drawing, S is a recording paper, 104 is a half-moon-shaped feeding roller provided for picking up the recording paper loaded on the cassette, and 105 is a rotatable free member provided coaxially with the feeding roller 104. Paper feed roller 10
Reference numeral 7 denotes a separation pad provided to separate and feed the recording paper S one by one when the feeding roller 104 feeds the paper.
Pad pressure spring provided to press against
Reference numerals 9a and 109b denote U-shaped conveyance guides provided to guide the picked-up recording paper S to the conveyance roller pair 110.

[0006] With such a configuration, the leading end of the recording paper stacked on the cassette is picked up by the feeding roller 104 and separated by the separation pad 107 into one sheet.
When the feeding roller 104 makes two rotations, it passes between the conveyance guides 109a and 109b, and the conveyance roller pair 110
And is conveyed to the subsequent image forming means.

[0007]

However, conventionally, a material having no conductivity or poor conductivity has been used for the conveyance guide, and when a recording material is conveyed while sliding on the material. Static electricity may be generated, causing sticking and inconvenient load on transportation. Such a load causes a jam while the recording material is being conveyed, and reduces the accuracy of image formation.

For example, in the case of FIG. 7 described above, after the feed roller 104 makes two rotations, the recording paper is fed by the paper feed roller 105.
The sheet is transported by the transport roller pair 110 in a state as shown in FIG. At this time, the pressing force by the separation pad 107 acts as a back tension when the recording paper S is transported, and the recording paper is transported between the separation pad 107 and the transport roller pair 110 while frictionally contacting the transport guide 109b. For this reason, as the number of prints increases, static electricity accumulates in the transport guide 109a, and the back tension of the recording paper further increases. As a result, the conveyance of the recording paper S to the image forming unit by the conveyance roller pair 110 becomes unstable, and there is a problem that the image shrinks in the conveyance direction or the image becomes uneven.

In the configuration of FIG. 7, the separation pad 107 and the transport roller pair 11
While the sheet is conveyed with tension between 0 and 0, the recording sheet S also comes into frictional contact with the stationary feed roller 104 due to the relative relationship between the feed guide, the feed roller, and the feed roller (shaded area). Since the surface of the feed roller 104 is formed of a material (rubber or the like) having a high coefficient of friction in order to pick up the recording paper, in such a case, the back tension is further increased to cause deterioration of an image.

The present application has been made in order to solve the above-mentioned problems of the prior art, and an object of the present invention is to provide high-precision recording material conveyance without applying an extra load when conveying the recording material. It is an object of the present invention to provide an image forming apparatus that can realize the image forming apparatus with high accuracy.

[0011]

In order to achieve the above object, according to the present invention, there is provided a feeding means for feeding a placed recording material, and an image forming means for forming an image on a surface of the recording material. ,
A discharging unit for discharging the recording material in the apparatus, and a conveying path from the feeding unit to the discharging unit via the image forming unit, and the recording material being conveyed to the conveying path. In the image forming apparatus provided with a transport guide that guides the sliding guides, the transport guide is formed of a conductive material.

In this case, it is preferable that the conveyance guide is provided at a position upstream of the image forming means in the conveyance direction and at a position where the recording material can be stretched between the conveyance guide and the image forming means.

[0013] Conveying means for conveying the recording material in a direction different from the feeding direction of the recording material by the feeding means is provided between the image forming means and the feeding means, and is provided between the feeding means and the conveying means. The transport path is bent, and the transport guide is preferably provided on the inner peripheral side of the bent transport path.

It is also preferable that the conveying means is disposed substantially above the feeding means, and the conveying guide has a substantially U-shape.

It is also preferable that the conveying means is disposed substantially below the feeding means, and the conveying guide has a substantially U-shape.

It is also preferred that the transport guide is made of a conductive plastic.

In the conveyance guide, it is preferable that a projection is formed on a surface for guiding the recording material.

A feeding unit for feeding the placed recording material; an image forming unit for forming an image on the surface of the recording material; a conveying path from the feeding unit to the image forming unit; A conveyance guide for guiding the recording material being conveyed while sliding on the conveyance path is provided. The feeding means is a feeding roller having a half-moon cross section, and the feeding roller performs a predetermined rotation operation. In the image forming apparatus which is controlled to stop at the home position after conveying the recording material to the conveying means, a feeding roller covering unit for avoiding contact of the recording material with the feeding roller in a stopped state. Is provided on the transport guide.

[0019]

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, the dimensions of the components described in this embodiment,
The material, shape, relative arrangement, and the like are not intended to limit the scope of the present invention only to them unless otherwise specified.

(Embodiment 1) FIG. 2 is a schematic configuration diagram of a laser printer using an electrophotographic system as an image forming apparatus according to a first embodiment of the present invention.

In FIG. 2, 1 is a cassette for storing recording paper, 2 is a stacked recording paper, 3 is a middle plate on which the recording paper 2 is placed, and 4 is a pickup for the recording paper 2 on the middle plate. The feeding roller provided for this purpose has a half-moon-shaped cross section.

Reference numeral 5 denotes a paper feed roller provided coaxially with the feed roller 4 and configured to be free of rotation, and is provided on both sides of the feed roller 4 as shown in a perspective view of FIG. Here the diameter d ₅ of the sheet feeding roller 5 d ₅ ≦ relative to the diameter d ₄ of the feeding roller
and it has a d _4.

Reference numeral 6 denotes a pressurizing spring provided to press the recording paper 2 against the intermediate plate 3 against the feed roller 4. Reference numeral 7 separates the recording paper 2 one by one when the feed roller 4 feeds. Reference numeral 8 denotes a pad pressing spring provided to press the separation pad 7 against the feed roller 4 and the paper feed roller 5. These members 1 to 8 are arranged below the apparatus, and constitute a feeding means as a whole.

9a and 9b are U-shaped conveyance guides,
It is provided to guide the picked-up recording paper S to a conveying roller pair 10 which is a conveying means.

A process cartridge 11 has a photosensitive drum 11a, toner (not shown), and a developing roller 11b and forms a toner image on the photosensitive drum 11a. 12
Is a laser beam scanning means provided for forming a latent image by a laser beam on the photosensitive drum 11a, and has a laser light source (not shown), a polygon mirror 12a, and a folding mirror 12b. Reference numeral 13 denotes a transfer roller provided for transferring a toner image formed on the photosensitive drum 11a onto recording paper. Reference numeral 14 denotes a fixing device for thermally fixing the toner on the recording paper. The fixing roller 14a and the heater 14
b, a pressure roller 14c. Above, 11-1
The image forming means is constituted by the members 4.

The positional relationship between the conveyance guides 9a and 9b and the image forming means is such that the recording paper S can be stretched between them as shown in the figure.

Reference numeral 15 denotes a discharge roller as discharge means provided for discharging recording paper onto a discharge tray 16;
Is an exterior cover, 18 is an openable / closable cover provided to open and close to take out the process cartridge, 19 is a printed circuit board integrally formed with a power supply unit and an engine controller, and 20 is a shield provided for shielding the printed circuit board 19. Case.

In this configuration, the recording paper is fed by the feed roller 4
Makes two rotations to reach the transport roller pair 10. Therefore, another conveying roller pair is not required between the feeding roller 4 and the conveying roller pair 10, and the apparatus can be reduced in size and cost.

FIG. 1 is a view best showing the features of the present invention, and is an enlarged view showing a schematic configuration of a portion from a feeding means to a conveying means.

In the figure, the transport guide 9b provided on the inner peripheral side of the transport path is made of a conductive resin material (surface resistance of 10 ⁶ Ω) such as a conductive plastic, and has a copper wire (not shown). ) Is electrically grounded.

In FIG. 1, S denotes a recording sheet picked up by a feeding roller and conveyed by a conveying roller pair 10. The leading end of the recording paper S has already passed through the transfer roller, and a part of the recording paper (near the rear end) is in a state of being sandwiched between the paper feed roller and the separation pad. Therefore, the recording paper is conveyed while being in frictional contact with the conveyance guide 9b. However, since the transport guide 9b is formed of a conductive material, the accumulation of static electricity is small, and the increase in back tension due to static electricity is extremely small. Further, when the half-moon feeding roller is stopped at the home position, a feeding roller covering portion (cross-hatched portion) for preventing the recording paper S from contacting the feeding roller is provided. Even if the recording paper is back-tensioned by the pad 7, the tangent connecting the separation pad, the nip portion of the paper feed roller, and the conveyance guide (that is, the conveyance path of the recording paper S) is positioned outside the surface of the feeding roller 4. And the recording paper does not touch the surface of the feed roller. Therefore, there is no increase in back tension due to contact between the surface of the feed roller and the recording paper.

As is apparent from the above description, according to the present embodiment, it is possible to reduce the transport resistance (back tension) caused by the contact between the transport guide and the recording paper and between the feeding roller and the recording paper. Therefore, even if the recording sheet is present at the position as shown in FIG. 1, the conveyance of the recording sheet by the conveying roller pair can be stabilized, and a beautiful image faithful to the image signal can be formed on the recording sheet.

In this embodiment, the guide surface of the transport guide 9b has been described as having a smooth surface. However, the transport guide 9b may be formed with protrusions (ribs). Further, in this embodiment, an example in which a conductive resin material is used for the transport guide 9b is introduced, but a metal material such as a sheet metal can be used.

(Embodiment 2) FIG. 4 is an enlarged view showing a schematic configuration of a portion from a feeding means to a conveying means of an image forming apparatus according to a second embodiment of the present invention.

In the first embodiment, the feeding roller constituting the feeding means has a half-moon cross section. In the present embodiment, as shown in FIG. A feed roller having a circular cross section is used. Reference numeral 24 denotes an electromagnetic clutch which is provided to be connected to the feeding roller and is provided for controlling the driving of the feeding roller. The feed roller 23 and the electromagnetic clutch 24 are coaxially connected as shown in FIG.

In this embodiment, when the recording paper is fed, the electromagnetic clutch is turned on and the power of a drive source (not shown) is transmitted to the feed roller 23, and the feed roller 23 rotates. Then, after the leading end of the recording paper reaches the transport roller pair 10, the electromagnetic clutch is turned off, and the feeding roller 23 is in a rotation-free state. At this time, the recording paper is
The recording paper is conveyed while being in frictional contact with the conveyance guide 9b. Here, the conveyance guide 9b is formed of a conductive material in the same manner as in the first embodiment, so that the conveyance roller pair 1
0 can stably convey the recording paper, and a good image can be formed on the recording paper.

It is needless to say that the load can be reduced by supporting the transport guide 9b with a spring or the like so as to float the transport guide 9b.

Since other structures and operations are the same as those of the first embodiment, the same components are denoted by the same reference numerals and description thereof will be omitted. (Embodiment 3) FIG. 6 shows an image forming apparatus according to a third embodiment of the present invention.

In the first embodiment, the feed roller is located below the transport roller pair 10 and the process cartridge 11, whereas in the present embodiment, the feed roller is located above.

FIG. 6 shows a state immediately after the recording sheet S is conveyed by the conveying roller pair 10 to the nip portion between the photosensitive drum 11a and the transfer roller 13 after the feeding roller 4 has completed the predetermined feeding operation and returned to the home position. The state of is shown.

In this state, the recording paper S is conveyed while being in frictional contact with the conveyance guide 9b (hatched portion) as in the first embodiment. The conveyance of the recording paper by the roller pair 10 can be stabilized, and a good image can be formed on the recording paper.

Since other structures and operations are the same as those of the first embodiment, the same components are denoted by the same reference numerals and description thereof will be omitted.

[0043]

According to the present invention, a conveying guide provided at a position upstream of the image forming means in the conveying direction and at which a recording material can be stretched between the conveying means and the image forming means is formed of a conductive material. Accordingly, an extra load due to static electricity is not applied to the recording material at the time of the conveyance, so that the recording material can be conveyed with high accuracy and the image can be formed.

Further, the feeding guide is provided with a feeding roller covering portion for avoiding contact of the recording material with the feeding roller when the half-moon feeding roller is stopped.
Since no extra load due to sliding of the feeding roller is applied when the recording material is conveyed, highly accurate recording material conveyance and image formation can be realized.

If the conveyance guide is provided on the upstream side in the conveyance direction with respect to the image forming means and at a position where the recording material can be stretched between the conveyance guide and the image forming means, the image formation on the recording material Since the conveyance at the time can be stabilized, an image faithful to the image signal can be formed on the recording material.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram illustrating a portion from a feeding unit to an image forming unit of an image forming apparatus according to a first embodiment of the present invention.

FIG. 2 is an overall schematic configuration diagram of the image forming apparatus according to the first embodiment of the present invention.

FIG. 3 is a perspective view showing peripheral components of a feeding roller used in the image forming apparatus according to the first embodiment of the present invention.

FIG. 4 is a schematic configuration diagram showing a portion from a feeding unit to an image forming unit of an image forming apparatus according to a second embodiment of the present invention.

FIG. 5 is a perspective view showing peripheral components of a feed roller used in an image forming apparatus according to a second embodiment of the present invention.

FIG. 6 is an overall schematic configuration diagram of an image forming apparatus according to a third embodiment of the present invention.

FIG. 7 is a schematic configuration diagram showing a portion from a feeding unit to an image forming unit of a conventional image forming apparatus.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 cassette 2 recording paper (stacked) 3 middle plate 4 feed roller 5 feed roller 6 pressure spring 7 separation pad 8 pad pressure spring 9a, 9b transport guide 10 transport roller pair 11 process cartridge 12 laser beam scanning Means 13 Transfer roller 14 Fixing unit 15 Discharge roller 16 Discharge tray 17 Exterior cover 18 Opening / closing cover 19 Printed circuit board 20 Shield case

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masaaki Nishikawa 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (7)

[Claims] An image forming unit configured to form an image on a surface of the recording material; a discharging unit configured to discharge a recording material in the apparatus; And a transport path through the image forming unit to the discharge unit, wherein the transport path is upstream of the image forming unit in the transport direction with respect to the image forming unit and is recorded between the image forming unit and the image forming unit. An image forming apparatus provided with a conveyance guide that guides a recording material being conveyed while sliding on a position where a material can be stretched, wherein the conveyance guide is formed of a conductive material. 2. The image forming apparatus according to claim 1, further comprising a conveying unit configured to convey the recording material in a direction different from a recording material feeding direction by the feeding unit, between the image forming unit and the feeding unit. 2. The image forming apparatus according to claim 1, wherein a conveyance path between the conveyance means and the conveyance unit is bent, and the conveyance guide is provided on an inner peripheral side of the bent conveyance path. 3. 3. The image forming apparatus according to claim 2, wherein the transport unit is disposed substantially above the feed unit, and the transport guide has a substantially U shape. 4. An image forming apparatus according to claim 3, wherein said transport means is disposed substantially below said feed means, and said transport guide is substantially U-shaped. 5. The image forming apparatus according to claim 1, wherein said transport guide is formed of conductive plastic. 6. The conveyance guide according to claim 1, wherein a projection is formed on a surface for guiding the recording material.
6. The image forming apparatus according to any one of claims 1 to 5, 7. A feeding means for feeding a loaded recording material, an image forming means for forming an image on the surface of the recording material, and a conveying path from the feeding means to the image forming means. A conveyance guide that guides the recording material being conveyed in sliding contact with the conveyance path, wherein the feeding means is a feeding roller having a half-moon cross section, and the feeding roller rotates at a predetermined speed. In an image forming apparatus which is controlled to stop at a home position after a recording material is conveyed to a conveying unit by an operation, a feeding roller for avoiding contact of the recording material with the feeding roller in the stopped state. An image forming apparatus, wherein a covering portion is provided on the transport guide.