JP2002080143A - Guide for transfer material to transfer position and image forming device using the same - Google Patents

Abstract

(57) [Summary] [Problem] To prevent the occurrence of shock jitter by sufficiently reducing a shock when a transfer material hits an image carrier and enters a transfer position without increasing the number of parts, thereby preventing the occurrence of shock jitter and improving image quality. The aim is to significantly improve. SOLUTION: In a transfer material guide device to a transfer position in an image forming apparatus, which guides a transfer material P by a guide member 11 to a transfer position 6, the transfer material P is in a direction orthogonal to a conveying direction of the transfer material P, The projection 40 is provided on a part of the guide member 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic image forming apparatus, for example, in which a transfer member such as a sheet or an OHP (over head projector) film is guided by a guide member to a transfer position. The present invention relates to a material guide device and an image forming apparatus using the same, such as a copying machine, a facsimile, a printer, and a multifunction peripheral thereof.

[0002]

2. Description of the Related Art Conventionally, as a transfer material guide device to a transfer position used in an image forming apparatus, for example, JP-A-8-16
The one disclosed in, for example, Japanese Patent No. 6731 is known.

In this transfer material guide device, for example, as shown in FIG. 9, a drum-shaped image carrier 1 is rotatably provided substantially at the center in the figure, and a transfer belt 2 is mounted on the image carrier 1 with a driving roller 3A, The transfer belt unit 5 stretched by the driven roller 3B and the application roller 4 is adjacent to the transfer belt unit 5.

The transfer belt unit 5 is urged against the image carrier 1 by an urging mechanism (not shown), and the driving force of the driving roller 3A causes the transfer position on the transfer belt 2, that is, the speed at the nip portion 6, to be changed. The carrier 1 is driven so as to have a substantially constant surface speed.

On the other hand, a sheet P, which is a transfer material, is conveyed by a pair of registration rollers 7 arranged upstream of the conveyance path, and a lower guide member 8 arranged to guide the conveyance direction to the nip portion 6. After the electrostatic latent image formed on the image carrier 1 is transferred to the nip portion 6 by the upper guide member 9 and transferred to the nip portion 6, a fixing device (see FIG. (Not shown).

In this transfer material guide device, by providing the upper guide member 9, the leading end of the sheet P is brought into contact with the upper guide member 9, and then guided to the nip portion 6 along the surface of the image carrier 1. As a result, a certain effect of reducing so-called shock jitter that causes image disturbance in the writing unit due to an impact caused by the sheet P abutting on the image carrier 1 is obtained.

[0007]

However, in such a transfer material guide device, the upper guide member 9 is provided in order to reduce the shock jitter generated in the writing section.
There was a problem that the number of parts increased and the cost increased.

Further, when the sheet P to be conveyed has a certain thickness, the rigidity thereof is strong, so that it is difficult to sufficiently reduce the shock when the sheet P hits the image carrier 1 and enters the nip portion 6. As a result, there is still an insufficient problem that a position shift occurs in the writing portion of the image carrier 1 to generate a shock jitter.

Further, in this transfer material guide apparatus, since the sheet P enters the nip portion 6 while sliding on the lower guide member 8, the lower guide member 8 is charged, and the sheet P passing therethrough is charged. As a result, the nip 6 may cause image disturbance due to uneven transfer.

In view of the above circumstances, a first object of the present invention is to reduce the cost without increasing the number of components and sufficiently reduce the shock when the transfer material hits the image carrier and enters the transfer position. It is another object of the present invention to prevent the occurrence of shock jitter in the writing section due to the impact, and thus to significantly improve the image quality.

At that time, a second problem is to guide the transfer material to the transfer position without causing unnatural distortion or skew or wrinkles in the entire transfer material.
A third object is to reduce the area of contact between the guide member and the transfer material, and to improve the transferability of the transfer material.

Further, a fourth problem is to prevent the transfer material from being charged when passing through the lower guide member and causing image disturbance at the nip portion due to uneven transfer, thereby preventing deterioration of image quality. Is to do.

[0013]

According to the first aspect of the present invention, there is provided a transfer position in an image forming apparatus, wherein a transfer material is guided by a guide member to a transfer position. In the apparatus for guiding a transfer material to a transfer member, a protrusion is provided on a part of the guide member in a direction orthogonal to a transfer direction of the transfer material.

According to a second aspect of the present invention, in order to solve the second problem, in the first aspect of the present invention, a projection is provided at the center of the guide member in a direction orthogonal to the transfer material conveying direction. Is provided.

According to a third aspect of the present invention, in order to solve the third problem, in the first or second aspect of the present invention, the guide member is provided with a plurality of guide ribs for guiding the transfer material,
Of these guide ribs, one that is larger than the other guide ribs is used as the projection.

According to a fourth aspect of the present invention, in order to solve the second problem, in the first, second or third aspect of the present invention, the projection is formed as a separate body and is provided so as to freely enter and exit the guide member. , And is urged in a protruding direction.

According to a fifth aspect of the present invention, in order to solve the fourth problem, in the first, second, third, or fourth aspect, the projection has conductivity. It is.

According to a sixth aspect of the present invention, in order to solve the first problem, the image forming apparatus is provided with a transfer material guide device to the transfer position according to the first aspect.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows a schematic configuration of an internal mechanism of a laser copying machine, which is an image forming apparatus provided with a transfer material guide device to a transfer position according to the present invention. In the figure, reference numeral 10 denotes a copying machine main body.

A drum-shaped image carrier 1 is provided in the apparatus main body 10, and a charger 12, a developing device 13, a transfer material guide device 14, a cleaning device 15, and the like are arranged therearound. Above them, a laser writer 16 is provided.
Although not shown, the laser writer 16 includes a light source such as a laser diode, a rotating polygon mirror for scanning,
A scanning optical system such as a polygon motor and an fθ lens is provided.

A fixing device 17 is provided on the left side of the cleaning device 15 in the drawing. The fixing device 17 is provided with a fixing roller 18 having a built-in heater and a pressure roller 19 pressed against the fixing roller 18 from below.

A document reading device 20 is provided at an upper portion in the apparatus main body 10. The light source a,
A plurality of mirrors b, an imaging lens c, a CCD (Charge Coupl
ed Device).

On the other hand, a duplex unit 22 and a paper feed cassette 23 are provided at the lower part in the apparatus main body 10 in two upper and lower stages. From the duplex unit 22 and the paper feed cassette 23,
There is provided a paper discharge path leading to a paper supply path 24 extending below the image carrier 1. The reversing path 26 is formed in the duplex unit 22 by branching from the middle of the sheet discharge path 25 extending from the exit of the fixing unit 17.

A contact glass 27 is provided on the upper surface of the apparatus main body 10 as in the prior art. In order to cover the contact glass 27, on the device main body 10,
An automatic document feeder 28 is attached to open and close freely.

On the right side of the apparatus main body 10, a manual feed tray 29 for guiding a manual feed sheet to the paper feed path 24 is provided to be openable and closable. On the other hand, on the left side of the device body 10,
Sorter 30 for receiving sheets discharged through paper discharge path 25
Attach. Then, the apparatus main body 10 is connected to the sheet feeding table 3.
1. In the paper feed table 31, paper feed cassettes 23 are provided in multiple stages.

When making a copy using this laser copying machine, the original is set on the automatic document feeder 28, or the automatic document feeder 28 is opened and the original is set directly on the contact glass 27. I do. Then, the user pushes a start switch (not shown) to drive the automatic document feeder 28 and conveys the original conveyed onto the contact glass 27 or the original set on the contact glass 27 in advance by the original reading device 20. Read in units.

At the same time, a suitable paper feed roller 33 is rotated,
Corresponding paper feed cassettes 23 among a plurality of paper feed cassettes 23 provided in multiple stages in the apparatus main body 10 and the paper feed table 31
A sheet, which is a transfer material, is fed out from the inside, is fed into the paper feed path 24, is conveyed by the conveying roller 34, and stops against the registration roller pair 7. Then, the registration roller pair 7 is rotated in synchronization with the rotation of the image carrier 1, and is sent below the image carrier 1.

Alternatively, the paper feed roller 3 in the manual paper feed unit
6, the manual sheet set on the opened manual feed tray 29 is inserted into the paper feed path 24, and the registration roller pair 7 is moved downward under the image carrier 1 in synchronization with the rotation of the image carrier 1. And send.

On the other hand, when a start switch (not shown) is pressed, the image carrier 1 is simultaneously rotated clockwise in the figure. Then, as the image carrier 1 rotates, first, the charger 12
To uniformly charge the surface, and then the above-described original reading device 2
The laser writer 16 irradiates a laser beam in accordance with the read content read at 0 to form an electrostatic latent image on the surface of the image carrier 1. Visualize the electrostatic latent image.

Then, the visible image is transferred by the transfer material guide device 14 to the sheet fed below the image carrier 1 as described above. The residual toner on the image carrier 1 after the image transfer is removed and cleaned by the cleaning device 15 to prepare for the next similar image formation.

On the other hand, the sheet after the image transfer is conveyed to the fixing device 17 by the transfer material guide device 14 and heat and pressure are applied by the fixing roller 18 and the pressure roller 19 to fix the transferred image. After that, the sheet is delivered
5 and is sorted into a sorter 30 and discharged.

When recording is also performed on the back side of a sheet using this copying machine, after recording on one side of the sheet, the sheet enters the duplex unit 22 through a reversing path 26, where it is reversed and again below the image carrier 1. To the image carrier 1
After the image formed on the upper surface is similarly transferred to the back surface, the sheet is discharged to the sorter 30.

Here, the transfer material guide device 14 is provided with a drum-shaped image carrier 1 at a substantially center in the figure as shown in FIG. A transfer belt unit 5 in which a transfer belt 2 is stretched by a driving roller 3A, a driven roller 3B, and an application roller 4 is adjacent to the image carrier 1.

The transfer belt unit 5 is urged against the image carrier 1 by an urging mechanism (not shown), and the speed at the nip 6 which is the transfer position on the transfer belt 2 is changed by the driving force of the driving roller 3A. The carrier 1 is driven so as to have a substantially constant surface speed.

On the other hand, a pair of registration rollers 7 and a lower guide member 8 for guiding the conveying direction to the nip portion 6 are arranged upstream of the conveying path of the sheet P as the transfer material. P is guided to the nip portion 6, where the electrostatic latent image formed on the image carrier 1 is transferred, and then transferred to a fixing device (not shown) disposed downstream of the transport path by the transfer belt 2. It is adapted to be transported.

In practice, as shown in FIG. 3, the lower guide member 11 is provided on one surface 11A in contact with the sheet P and has a rib-like shape in a part of a direction b perpendicular to the conveying direction a of the sheet P. Is provided.

Incidentally, the protrusion 40 may be in the form of a hump, and the position of the protrusion 40
Although both end portions on 1A and a center portion are conceivable, the lower guide member 11 is formed at a substantially center portion on one surface 11A of the lower guide member 11 in consideration of avoiding skew and wrinkling of the sheet P to be guided. It is desirable.

As described above, in this transfer material guide device, by providing the projection 40 on the lower guide member 11,
As shown in FIG. 4, the sheet P to be guided enters the nip portion 6 with its center part slightly raised, so that the center part of the leading end of the sheet P and both end parts have a slight time difference. The sheet P is provided for contact with the image carrier 1.
Impact on the image carrier 1 can be sufficiently reduced, and the occurrence of shock jitter in the writing section due to this can be prevented.

As shown in FIG. 5, the lower guide member 11 is provided with a plurality of guide ribs 41 at regular intervals in a direction orthogonal to the sheet P conveying direction on one surface 11A. A protrusion larger than the guide rib 41 may be used.

Further, as shown in FIG.
0 is formed separately from the lower guide member 11, a hole 11B is formed in the lower guide member 11, and a projection 50 is provided in the hole 11B so that the pin 50A can be freely moved in and out about the center of rotation.
Further, an elastic body 51 may be provided between the inner wall 11C inside the lower guide member 11 and the protrusion 50, and the elastic body 51 may urge the protrusion 50 in a protruding direction.

As a result, the projection 50 rises only at the center of the sheet P when the leading edge of the sheet P enters, and otherwise lowers due to the weight of the sheet P as shown in FIG. 6B. Even when the portion 50 is formed at an ideal height, after the leading end of the sheet P has passed, the sheet P
It is possible to guide the sheet P to the nip portion 6 with a further time difference between the central portion and both end portions at the leading end portion without causing unnatural distortion or generating skew or wrinkles on the whole, Thus, the sheet P is
Can be sufficiently reduced.

Further, as shown in FIGS. 7A and 7B, the projection 60 is formed separately from the lower guide member 11 using a conductive material such as a carbon-containing resin material. 11 may be provided so as to be detachable. Incidentally, the lower guide member 11 may be entirely formed using a conductive material.

Thus, it is possible to prevent the sheet P guided while sliding on the protrusions 60 from being charged and causing image disturbance due to uneven transfer at the nip portion 6 beforehand.

In this case, as shown in FIG. 8, the lower guide member 11 and the projection 70 are integrally formed using an insulating molding material or the like, and a conductive material or a surface active material is formed on one surface 11A. The same effect can be obtained even if the antistatic layer 71 is provided by coating using such as to prevent the protrusion 70 from being charged. Incidentally, it is clear that the antistatic layer 71 may be provided only in the portion of the protrusion 70.

[0045]

As described above, according to the present invention, since the guide member is provided with the projection, the transfer material to be guided is allowed to enter the transfer position in a slightly raised state. Since the tip of the transfer member comes into contact with the image carrier with a slight time difference, the cost can be reduced without increasing the number of components, and the impact generated when the transfer material contacts the image carrier is sufficiently reduced. Therefore, it is possible to prevent the occurrence of shock jitter in the writing section due to the above, and thus it is possible to significantly improve the image quality.

Further, according to the second aspect of the present invention, the projection is provided substantially at the center of the guide member in the direction orthogonal to the direction of transport of the transfer material, so that the projection is aligned with the transport direction of the guide member. Skew and wrinkling of the transfer material guided by the guide member can be avoided as compared with the case where the transfer material is provided at both ends in the orthogonal direction.

Further, according to the third aspect of the present invention, the guide member is provided with a plurality of guide ribs for guiding the transfer material, so that the area where the guide member contacts the transfer material is reduced, and the transfer material is made smoother. To the transfer position,
It is possible to improve the transfer property of the transfer material in the guide member, and by using a projection that is larger than the other guide ribs among the guide ribs, when the transfer material as described above comes into contact with the image carrier, The resulting shock can be sufficiently reduced. As a result, it is possible to prevent the occurrence of shock jitter in the writing section due to the impact, and thus to significantly improve the image quality.

Further, according to the fourth aspect of the present invention, the projection is formed as a separate body, is provided so as to be able to enter and exit the guide member, and is urged in the projecting direction so that the projection is moved to the transfer position. Only when the leading edge of the transfer material enters, a part of the transfer material is raised, and the rest is lowered by the weight of the transfer material. Therefore, even when the protrusion is formed at an ideal height, the transfer material is unnatural. The transfer material can be brought into contact with the image carrier with a further time lag at its leading end without causing distortion, skew or wrinkling.

Further, according to the fifth aspect of the present invention, by providing the protrusion with conductivity, the transfer material guided by sliding on the protrusion is charged by friction with the protrusion, It is possible to prevent image disturbance due to transfer unevenness at the transfer position, and to prevent deterioration of image quality.

Further, according to the invention of claim 6, by using the transfer material guide device to the transfer position of claim 1, the image forming apparatus having the effect of the invention of claim 1 can be provided. Obtainable.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an internal mechanism of a laser copying machine according to an embodiment.

FIG. 2 is a schematic sectional view showing the transfer material guide device.

FIG. 3 is a schematic perspective view showing the lower guide member.

FIG. 4 is a schematic perspective view showing a state in which a sheet is guided by a lower guide member.

FIG. 5 is a schematic perspective view showing another lower guide member.

FIG. 6 is a schematic perspective view showing another lower guide member.

FIG. 7 is a schematic perspective view showing another lower guide member.

FIG. 8 is a schematic perspective view showing another lower guide member.

FIG. 9 is a schematic sectional view showing a conventional transfer material guide device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image carrier 2 Transfer belt 5 Transfer belt unit 6 Nip part (transfer position) 11 Lower guide member (guide member) 11A One surface 40 Projection part 50 Projection part 60 Projection part 70 Projection part 41 Guide rib 51 Elastic body 71 Antistatic layer P Sheet (transfer material).

Claims (6)

[Claims] 1. A transfer material guide device for transferring a transfer material to a transfer position in an image forming apparatus, wherein the transfer material is guided by a guide member to a transfer position. A transfer material guide device to a transfer position, wherein a protrusion is provided on a part of a member. 2. The apparatus according to claim 2, wherein the protrusion is provided at a center of the guide member in a direction orthogonal to a transfer direction of the transfer material.
The transfer material guide device to the transfer position according to claim 1. 3. The guide member is provided with a plurality of guide ribs for guiding the transfer material, and among the guide ribs,
The one that is larger than the other guide ribs is used as the protrusion,
The transfer material guide device to the transfer position according to claim 1. 4. The transfer material to a transfer position according to claim 1, wherein the protrusion is formed separately, provided so as to be able to enter and exit the guide member, and biased in a protruding direction. Guide device. 5. The method according to claim 5, wherein the projection has conductivity.
The transfer material guide device to the transfer position according to claim 1, 2, 3, or 4. 6. An image forming apparatus using the transfer material guide device to the transfer position according to claim 1.