JP3659163B2 - Image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image forming apparatus such as an electrophotographic copying machine, an electrophotographic printer (such as a laser beam printer or an LED printer), a facsimile machine, and a word processor.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, as an image forming apparatus that forms an image on a printing medium such as paper, an image forming apparatus that forms an image on a printing medium (for example, recording paper) by an electrophotographic image forming method, such as a laser beam printer, is known. ing.
[0003]
In this electrophotographic image forming method, an electrostatic latent image is formed by subjecting an electrophotographic photosensitive drum uniformly charged by a charging means to selective exposure according to image information. Is developed with toner by a developing means to form a toner image on the photosensitive drum, and then the toner image on the photosensitive drum is transferred onto a recording sheet by a transfer roller to form an image.
[0004]
In this type of image forming apparatus, a photosensitive drum, a charger for charging the photosensitive drum, a developing roller for supplying a developer to the photosensitive drum for developing an electrostatic latent image formed on the photosensitive drum, and the like are provided. A process cartridge system is adopted in which the cartridge is integrally formed and the cartridge can be attached to and detached from the mounting portion of the apparatus main body.
[0005]
[Problems to be solved by the invention]
By the way, in the image forming apparatus described above, a pair of metal support frames are arranged on the left and right sides of the apparatus as a basic structure constituting the apparatus main body, and the process cartridge and the recording paper are disposed between the support frames. There are those in which various rollers and the like for transporting are arranged.
[0006]
However, in the case of this structure, when the device is placed on, for example, an uneven desk or floor, the device itself may be twisted. Therefore, the accuracy required for the recording paper feeding operation and image formation may not be ensured.
In other words, between the left and right support frames, there are a pickup roller that sends the recording paper from the stacker to the conveyance path, a conveyance roller that conveys the recording paper taken out by the pickup roller, a registration roller that aligns the top of the recording paper, etc. Is supported by the support frame, and a photosensitive drum and a transfer roller are also arranged. However, if the left and right support frames are twisted, the position of the above-described rollers and the like is shifted, resulting in recording paper. However, there is a problem that the paper feeding and paper feeding cannot be performed well and a precise image cannot be formed.
[0007]
The present invention has been made to solve the above-described problems, and provides an image forming apparatus capable of preventing the twisting between the left and right support frames and suitably transporting the print medium and forming an image. With the goal.
[0008]
[Means for Solving the Problems and Effects of the Invention]
(1) In order to achieve the above-mentioned object, the invention of claim 1 is characterized in that a pair of left and right support frames constituting the apparatus main body and a support medium supported between the support frames and image formation of the print medium from the supply area. An image having a plurality of conveying members that convey the print medium and a conveyance path that includes a plurality of conveying members and a guide member that connects the conveying members to form an image on the printing medium by conveying to the area. In the forming apparatus, a plurality of conveying members are arranged so as to constitute a curved conveying path in the apparatus main body, and the pair of support frames are connected by reinforcing members that fix both ends inside the curved curved line of the conveying path. It is characterized by.
[0009]
In the present invention, a conveyance path including a conveyance member (for example, various rollers) and a guide member (for example, a guide) is provided between the left and right support frames, and the plurality of conveyance members are curved in the apparatus main body. It arrange | positions so that a conveyance path | route may be comprised. Furthermore, a reinforcing member is disposed inside the curved conveyance path, and both ends of the reinforcing member are fixedly connected to the left and right support frames to prevent twisting between the support frames. Yes.
[0010]
Therefore, even when the image forming apparatus is placed on a non-flat desk, for example, the twist between the support frames is difficult to occur. Even if the twist is generated, the twist center is inside the curve of the conveyance path. Variations in the amount of deviation in the conveying member can be suppressed. Therefore, the printing medium can be smoothly conveyed (without causing skew or paper jam). Further, since the apparatus is prevented from being twisted, the position of the photosensitive drum, the transfer roller, or the like is not easily displaced, so that a precise image can be formed.
[0011]
(2) In addition to the structure described in claim 1, the invention of claim 2 develops a photosensitive drum on which an electrostatic latent image is formed and an electrostatic latent image on the photosensitive drum in the image forming area. A developing unit that develops a visible image on the photosensitive drum by developing with an agent, and a transfer unit that transfers the visible image to a printing medium on the photosensitive drum, and the plurality of conveying members include: It is characterized in that it is arranged in the transport path upstream of the transfer position of the visible image from the photosensitive drum to the printing medium.
[0012]
The present invention exemplifies the position of the conveyance path. In the present invention, the plurality of conveyance paths are arranged on the conveyance path upstream of the transfer position of the visible image from the photosensitive drum to the print medium, and the conveyance paths are not easily affected by twisting by the reinforcing member. Therefore, the printing medium can be smoothly conveyed and a precise image can be formed.
[0013]
(3) According to the invention of claim 3, in addition to the configuration described in claim 1 or 2, the conveying member includes a pick-up roller that sends out the print medium one sheet at a time from the stacker on which the print medium is laminated, and printing. A registration roller that aligns the leading ends of the medium, and a photosensitive drum and a transfer roller for forming an image by electrophotography and transferring the formed image to a printing medium.
[0014]
The present invention exemplifies a conveying member. These conveying members are arranged on the conveying path until the image is transferred to the printing medium, and particularly high accuracy is required for image formation.
In the present invention, the reinforcing member prevents the support frames from being twisted. Therefore, the positions of the pickup roller, the registration roller, the photosensitive drum, and the transfer roller are always arranged at their proper positions without being shifted. Yes. Accordingly, operations such as conveyance of the print medium and image formation by each member can be performed reliably.
[0015]
Further, even if the above-described twist occurs, the shift amounts at the positions of the respective transport members (each shift amount with respect to the same twist angle) can suppress mutual variations, so that the print medium is transported to the transfer position. Is performed well, and image transfer is also performed well.
[0016]
(4) In addition to the configuration described in claim 3, the invention of claim 4 is a roller (for example, a registration roller) that is another conveying member when the print medium is sandwiched between the photosensitive drum and the transfer roller. ).
This prevents the conveyance of the print medium from being skewed by a pair of rollers, which are other conveyance members, during transfer, and prevents the image at the transfer position from being disturbed.
[0017]
(5) In addition to the structure in any one of Claims 1-4, invention of Claim 5 is characterized by the conveyance member being arrange | positioned within the radius of 100 mm from the axial center of a reinforcement member.
In this invention, the conveyance member is arrange | positioned in the near position within the radius of 100 mm of a reinforcement member. Therefore, even when stress that applies twisting to the support frame is applied, the position of the conveying member is not greatly shifted, and for example, paper feeding and paper feeding can be performed smoothly, and a precise image is formed. be able to.
[0018]
Examples of the conveyance member include a pickup roller, a conveyance roller, a registration roller, a photosensitive drum, and a transfer roller.
(6) In addition to the structure in any one of Claims 1-5, the invention of Claim 6 is characterized in that the reinforcing member is a metal pipe.
[0019]
The present invention illustrates a reinforcing member. Here, since the metal pipe is used as the reinforcing member, even when the pipe is thin, sufficient strength can be ensured and the weight can be reduced.
(7) In the invention of claim 7, in addition to the structure of claim 6, the reinforcing member includes a fixing plate welded to both ends of a metal pipe, and is fixed to the support frame by the fixing plate. It is characterized by that.
[0020]
In the present invention, since the pipe is not directly connected to the support frame, but the pipe is fixed to the support frame via a fixing plate (integrated by welding), the stress applied to the support frame is twisted. Even when added, there is an effect that it is difficult to break from the connecting portion of the pipe. Further, for example, if the fixing plate and the support frame are screwed, there is an advantage that the reinforcing member can be easily fixed to the support frame.
[0021]
(8) The invention of claim 8 includes, in addition to the structure according to any one of claims 1 to 7, not only a reinforcing member but also one or a plurality of auxiliary plates having their both ends fixed to the left and right support frames. It is characterized by that.
The invention illustrates a further arrangement for preventing twisting of both support frames. In the present invention, since the auxiliary plate is fixed to both support frames in addition to the reinforcing member, there is a feature that it is more resistant to torsion than the case of only the reinforcing member.
[0022]
(9) The invention of claim 9 is characterized in that, in addition to the configuration of claim 8, an optical scanning device for image formation is mounted on the auxiliary plate.
In the present invention, an apparatus mounted on an auxiliary plate is illustrated, and here, an optical scanning device is mounted on the auxiliary plate.
[0023]
(10) The invention of claim 10 is characterized in that, in addition to the configuration of claim 8, a power source is arranged on the auxiliary plate.
In this invention, the apparatus arrange | positioned at an auxiliary | assistant board is illustrated, and here, the power supply is arrange | positioned at the auxiliary | assistant board.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of an image forming apparatus of the invention will be described in detail with reference to the drawings.
(Embodiment)
In the present embodiment, a laser beam printer (laser printer) will be described as an example of the image forming apparatus.
[0025]
a) First, the overall configuration of the laser printer according to the present embodiment will be described with reference to FIG.
FIG. 1 is a longitudinal sectional view showing a configuration of an apparatus main body (main body unit) 1 of the laser printer.
[0026]
As shown in FIG. 1, in the laser printer according to the present embodiment, a paper feed tray (stacker) 3 that is detachably inserted into the main body unit 1 is disposed below the main body unit 1. A support plate 5 is provided that is biased upward by a spring that does not.
[0027]
Above the support plate 5, as a conveying member, a supply roller that separates recording paper (corresponding to a print medium) held in a laminated form on the support plate 5 one by one and supplies it in the direction of the image forming unit 7. (Pickup roller) 9 is provided.
As will be described in detail later, a recording paper conveyance path from the pickup roller 9 to the image forming unit 7 includes a first conveyance roller pair 11 and a second conveyance roller pair 13 that convey the recording paper as conveyance members. A registration roller (registration roller) pair 15 for sequentially locking the leading end of the recording paper by correcting the correction and correcting the skew of the recording paper is sequentially disposed. In addition, a plurality of guide members (guides) 16 for guiding the recording paper along the transport path are appropriately disposed between these transport members so that the recording paper does not deviate from the transport path.
[0028]
The image forming unit 7 includes a photosensitive drum 23 provided in the process cartridge 21 and a transfer roller 25 disposed to face the photosensitive drum 23. Among these, the photosensitive drum 23 is disposed on the process cartridge 21 side, and the transfer roller 25 is disposed on the main unit 1 side. The registration roller pair 15, the photosensitive drum 23, and the transfer roller 25 also have a function as a conveying unit that conveys the recording paper in accordance with the operation.
[0029]
A fixing unit 35 including a heating roller 31 and a pressing roller 33 is provided on the downstream side (right side in the drawing) of the image forming unit 7 with a conveying belt 27 interposed therebetween.
Further, on the downstream side of the fixing unit 35, three pairs of paper discharge rollers 37a to 37c are arranged along the transport path, and on the upper surface of the main body unit 1, recording is discharged from the last paper discharge roller 37c. A paper discharge tray 39 for receiving paper is provided.
[0030]
A scanner unit 41 that exposes and scans the photosensitive drum 23 with the laser beam L is disposed between the paper discharge tray 39 and the process cartridge 21. Further, a low voltage power source 44 for supplying power to a controller or the like for controlling the entire apparatus is disposed below the image forming unit 7, and a photosensitive drum in the process cartridge 21 is disposed below the fixing unit 35. A power supply 46 for high voltage for applying a developing bias is disposed at 23.
[0031]
The scanner unit 41 includes various optical elements such as a polygon mirror 42 that is rotated by a motor 40 for the purpose of scanning laser light emitted from a laser diode (not shown) for image formation. Etc. are arranged.
b) Next, the process cartridge 21 will be described with reference to FIGS. FIG. 2 is a longitudinal sectional view showing the internal structure of the process cartridge 21.
[0032]
First, as shown in FIG. 1, the process cartridge 21 is detachably mounted (moving forward and backward in the directions of arrows A and B) in a mounting portion 17 that is a recess opening above the main unit 1. . The opening above the mounting portion 17 is always covered with a cover 19, and the process cartridge 21 can be attached and detached by opening the cover 19 by rotating it upward.
[0033]
As shown in FIG. 2, the process cartridge 21 is rotatably provided with a photosensitive drum 23 having a photosensitive layer on its surface, a charging roller 43 that uniformly charges the surface of the photosensitive drum 23, and a charging roller. A developing roller 45 is provided as a developing device for supplying toner to the surface of the photosensitive drum 23.
[0034]
Then, an electrostatic latent image is formed on the surface of the photosensitive drum 23 charged by the charging roller 43 by the laser light L incident from the scanner unit 41 through the exposure opening 21a. Subsequently, the developing roller 45 By supplying toner as a developer to the surface of the photosensitive drum 23, the electrostatic latent image is developed on the photosensitive drum 23 to form a toner image (visible image).
[0035]
In addition, the process cartridge 21 is triboelectrically charged with a toner feeding member 47 that feeds the toner contained in the toner container 21b toward the developing roller 45 while stirring, and the toner attached to the surface of the developing roller 45, Various known structures such as a layer thickness regulating blade 49 for thinning the toner image are provided.
[0036]
c) Next, an image forming procedure in the present embodiment will be described.
The recording paper taken out from the stacker 3 by the pickup roller 9 is sent to the registration roller pair 15 by the first and second transport roller pairs 11 and 13, where the skew of the recording paper is corrected.
[0037]
Thereafter, when the recording paper is sent to the image forming unit 7, the toner adhering to the photosensitive drum 23 passes between the transfer roller 25 when passing between the photosensitive drum 23 and the transfer roller 25. By being transferred to the recording paper, an image (toner image) is formed on the recording paper.
[0038]
The recording paper on which the toner image is formed is transported to the fixing unit 35 by the transport belt 27. The fixing unit 35 is sandwiched between the heating roller 31 and the pressing roller 33 and heated by the heating roller 31 to fix the toner image onto the recording paper, thereby completing the image formation.
[0039]
Thereafter, the recording paper on which the image is fixed is discharged to a paper discharge tray 39 provided on the upper surface of the main unit 1 through three pairs of paper discharge rollers 37a to 37c.
d) Next, the structure which prevents the twist of a support frame which is the principal part of this Embodiment is demonstrated based on FIGS.
[0040]
3 is a front view of the laser printer as viewed from the front, FIG. 4 (a) is a left side view of a support frame constituting a part of the frame, FIG. 4 (b) is a right side view of the support frame, FIG. FIG. 3 is a top view showing a state in which a support frame or the like is assembled.
(1) First, a structure such as a support frame will be described.
[0041]
As shown in FIG. 3, the laser printer according to the present embodiment has a configuration in which the cover 19 of the main unit 1 is opened and the process cartridge 21 is attached to the attachment portion 17. A pair of support frames (support plates) 51 and 53 made of a metal plate material are erected in parallel.
[0042]
As shown in FIG. 4, the support frames 51 and 53 have a large number of fixing holes 51a and 53a for fixing various members, a number of screw holes 51b and 53b for screwing, and a photosensitive drum. A large number of opening portions such as a large-diameter through hole 53 c for transmitting a driving force to 23 are provided. FIG. 4 shows only the main part of the opening.
[0043]
As shown in FIG. 5, the support frames 51 and 53 are basic structures constituting the main unit 1, and the support frames 51 and 53 are firmly connected between the support frames 51 and 53. For fixing, a reinforcing member 55 that is a metal rod-shaped pipe, a metal first auxiliary plate 57 on which the scanner unit 41 is mounted, and a metal second auxiliary plate 59 that covers the power source 46 are arranged. ing.
[0044]
Among them, as shown in FIG. 6, the reinforcing member 55 is formed by welding a substantially square steel plate material to both ends of a steel pipe (a fine hatched portion in FIG. 3) 55a. A fixing hole 55c is formed in the corner portion for screwing. Therefore, as shown in FIG. 5, the reinforcing member 55 is fixed to the left and right support frames 51 and 53 by the screws 56 passed through the fixing holes 55c.
[0045]
The first auxiliary plate 57 and the second auxiliary plate 59 are formed by bending a substantially rectangular plate material and punching out necessary portions to form openings. That is, the first auxiliary plate 57 and the second auxiliary plate 59 are bent at a substantially right angle so that both ends thereof are in contact with the left and right support frames 51 and 53, and a screw fixing fixing hole ( (Not shown) is provided. Accordingly, the first auxiliary plate 57 and the second auxiliary plate 59 are fixed to the left and right support frames 51 and 53 by the screws 58 passed through the fixing holes. The torsional strength of these auxiliary plates 57 and 59 is set to a value smaller than the torsional strength of the reinforcing member 55.
[0046]
As shown in FIG. 7, the above-described scanner unit 41 is disposed on the upper surface of the first auxiliary plate 57, and the second auxiliary plate 59 is disposed so as to cover the power supply 46.
In addition to the above-described configuration, a transfer roller support (transfer base: rough shaded portion in FIG. 3) 61 that supports the transfer roller 25 rotatably is attached between the support frames 51 and 53.
[0047]
(2) Next, the conveyance path will be described with reference to FIG.
As shown in FIG. 7, in this embodiment, transfer from the stacker 3 to the pickup roller 9, the first and second transport roller pairs 11 and 13, the registration roller pair 15, the photosensitive drum 23 and the transfer roller 25. The conveyance path on the upstream side of the position is curved substantially U-shaped as indicated by the one-dot chain line in the figure, and the reinforcing member 55 is disposed inside the curved line.
[0048]
That is, the transport path is a first transport roller comprising a pickup roller 9 and a plate-shaped guide member (separation pad) 16 facing the pickup roller 9 and a driven roller 11b that rotates with the movement of the drive roller 11a and the recording paper. Between the pair 11, between the second conveying roller pair 13 composed of the same driving roller 13 a and driven roller 13 b, between the pair of registration rollers 15 composed of the driving roller 15 a and driven roller 15 b, and between the photosensitive drum 23 and the transfer roller 25. The sheet is curved so that the recording sheet passes along the guide member 16.
[0049]
The pickup roller 9, the first and second conveying roller pairs 11, 13, the registration roller pair 15, the photosensitive drum 23, and the transfer roller 25 described above have a radius of 100 mm with the axial center of the pipe 55a of the reinforcing member 55 as the center. Is arranged so as to surround the pipe 55a.
[0050]
e) As described above, in the present embodiment, a curved conveyance path is formed between the left and right support frames 51 and 53, and the pickup roller 9, the first and second conveyances are performed along this conveyance path. Conveying members such as the roller pairs 11 and 13, the registration roller pair 15, the photosensitive drum 23 and the transfer roller 25, and the guide member 16 are disposed. In addition, a reinforcing member 55 is attached to the inner side (center side) of the curve of the transport path so as to couple the support frames 51 and 53 together. In other words, a plurality of conveying members are arranged so as to surround the reinforcing member 55.
[0051]
Therefore, even when a stress that gives twist to the image forming apparatus is applied, the position of each conveying member does not greatly deviate. For example, even when the image forming apparatus is placed on a non-flat desk, the support frames 51 and 53 are not easily twisted. Can be done. Further, since the apparatus is prevented from being twisted, the positions of the photosensitive drum 23 and the transfer roller 25 are not easily displaced, so that a precise image can be formed.
[0052]
This is because the installation position of the pipe 55a is set inside the curve of the conveyance path, so that the distance between the pipe 55a and the pickup roller 9, the distance between the pipe 55a and the first conveyance roller pair 11, the pipe 55a And the distance between the pipe 55a and the registration roller pair 15, and the distance between the pipe 55a and the photosensitive drum 23 and the transfer roller 25 are averaged. This is because the variation in the shift amount of the mounting position of the conveying member (roller) is reduced.
[0053]
Conversely, when the reinforcing member 55 is disposed outside the curve of the conveyance path, as shown in FIG. 8, the distance between the reinforcing member 55 and each conveying member is not averaged and is greatly different, and the deviation with respect to the same helix angle. The amount will vary greatly.
In addition, in the present embodiment, each conveying member is arranged within a radius of 100 mm from the axial center of the pipe 55a of the reinforcing member 55, that is, arranged at a position close to the pipe 55a. This also has the effect of being less susceptible to torsion.
[0054]
Further, in the present embodiment, not only the reinforcing member 55 but also the first auxiliary plate 57 and the second auxiliary plate 59 are fixed between the support frames 51 and 53, so that the resistance to twisting is further increased. Therefore, it is possible to more suitably carry the recording paper and form an image.
[0055]
Needless to say, the present invention is not limited to the above-described embodiment and can be implemented in various modes without departing from the technical scope of the present invention.
For example, other reinforcing members may be added to the reinforcing member 55 and the first and second auxiliary plates 57 and 59.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view illustrating a configuration of an apparatus main body (main body unit) of a laser printer according to an embodiment.
FIG. 2 is a longitudinal sectional view showing an internal structure of a process cartridge.
FIG. 3 is a front view of the laser printer as viewed from the front.
4A is a left side view of the support frame, and FIG. 4B is a right side view of the support frame.
FIG. 5 is a top view showing a structure including a support frame and a reinforcing member.
FIG. 6 is an exploded perspective view showing a reinforcing member.
FIG. 7 is an explanatory view showing the arrangement of a conveyance path and conveyance members from the side.
FIG. 8 is an explanatory diagram showing a difference in shift amount depending on the position of a reinforcing member.
[Explanation of symbols]
1 ... Main unit (main unit)
9 ... Pickup roller 11 ... First transport roller pair 13 ... Second transport roller pair 15 ... Registration roller pair 15,
16 ... Guide member (guide)
21 ... Process cartridge 23 ... Photoconductor drum 25 ... Transfer rollers 51, 53 ... Support frame 55 ... Reinforcement member 55a ... Pipe 57 ... First auxiliary plate 59 ... Second auxiliary plate

Claims (10)

A pair of left and right support frames constituting the apparatus body;
A plurality of conveying members that are supported between the support frames and convey the print medium from the supply area to the image forming area to form an image on the print medium;
A transport path composed of the plurality of transport members and a guide member that connects the transport members;
In an image forming apparatus comprising:
The plurality of conveying members are arranged to constitute the conveying path curved in the apparatus main body,
An image forming apparatus, wherein the pair of support frames are connected by a reinforcing member having both ends thereof fixed inside the curve of the transport path. In the image forming area, a photosensitive drum on which an electrostatic latent image is formed, a developing unit that develops the electrostatic latent image on the photosensitive drum with a developer, and forms a visible image on the photosensitive drum; A transfer device for transferring a visible image to a print medium is disposed on the photosensitive drum, and the plurality of conveying members are upstream of the transfer position of the visible image from the photosensitive drum to the print medium. The image forming apparatus according to claim 1, wherein the image forming apparatus is disposed in a conveyance path. The transport member forms an image by an electrophotographic method, a pickup roller that sends the print medium to the transport path one by one from the stacker on which the print media are stacked, a registration roller that aligns the front end of the print medium, and The image forming apparatus according to claim 1, wherein the image forming apparatus is a photosensitive drum and a transfer roller for transferring a formed image to the print medium. 4. The image forming apparatus according to claim 3, wherein when the print medium is sandwiched between the photosensitive drum and the transfer roller, the print medium is sandwiched between a pair of rollers that are other transport members. The image forming apparatus according to claim 1, wherein the conveying member is disposed within a radius of 100 mm from an axial center of the reinforcing member. 6. The image forming apparatus according to claim 1, wherein the reinforcing member is a metal pipe. The image forming apparatus according to claim 6, wherein the reinforcing member includes a fixing plate welded to both ends of a metal pipe, and is fixed to the support frame by the fixing plate. 8. The image forming apparatus according to claim 1, further comprising one or a plurality of auxiliary plates each having its both ends fixed to the left and right support frames in addition to the reinforcing member. 9. The image forming apparatus according to claim 8, wherein an optical scanning device for forming the image is mounted on the auxiliary plate. The image forming apparatus according to claim 8, wherein a power source is disposed on the auxiliary plate.

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