JP3571998B2 - Image forming device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image forming apparatus, and more particularly, to a configuration of a sheet feeding unit that conveys a sheet stored in a sheet storage unit toward a conveyance path.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, in an image forming apparatus employing an electrophotographic method such as an electrophotographic copying machine, a printer, a word processor, and a facsimile apparatus, and other recording methods, a sheet stored in a sheet storing unit is conveyed to an image forming unit, and an image is formed. There is a configuration in which a toner image formed by a forming unit is transferred to a sheet, and then the transferred image is fixed to the sheet.
[0003]
In such an image forming apparatus, sheet feeding means for conveying the sheet to the image forming unit, transfer means for transferring the toner image formed by the image forming unit to the sheet, and fixing means for fixing the transferred image to the sheet are provided. In some cases, the sheet is conveyed from a sheet feeding unit to a transfer unit to a fixing unit via a conveying path provided substantially horizontally or substantially vertically.
[0004]
Here, FIG. 6 shows a schematic configuration of a laser beam printer which is an example of such a conventional image forming apparatus. As shown in FIG. The transfer unit 52 is disposed substantially horizontally, and the fixing unit 53 is disposed substantially horizontally on the left side.
[0005]
An image forming unit 54 such as a process cartridge and a light source unit 55 such as a laser scanner are provided above a substantially horizontal sheet conveying path R that conveys the sheet P to the sheet feeding unit 51, the transfer unit 52, and the fixing unit 53. Is provided. With such a configuration, the laser beam printer 50 conveys the sheet P to the image forming unit, transfers the toner image formed by the image forming unit (image forming unit 54) to the sheet, and transfers the toner image on the sheet. Heat fixing is performed.
[0006]
On the other hand, FIG. 7 shows the configuration of another laser beam printer. This laser beam printer 50A has a paper feed unit 51 at the lower end, a transfer unit 52 at the center, and a fixing unit 53 at the upper end substantially vertically. At the same time, the image forming means 54 and the light source means 55 are arranged beside the sheet conveyance path R provided substantially vertically.
[0007]
By the way, in a conventional image forming apparatus having such a configuration, for example, in a laser beam printer 50 shown in FIG. 6, a paper feeding unit 51 for feeding a sheet P on a paper feeding tray 56 as shown in FIG. And a sheet conveying direction by a separating member 51b abutting on the sheet feeding roller 51a, and a sheet conveying path (hereinafter, referred to as a sheet transferring and conveying path) R1 from the sheet feeding means 51 to the transfer means 52. , 20 to 45 degrees. In the figure, reference numeral 57 denotes a conveying roller for conveying the sheet P separated and conveyed from the sheet feeding means 51 toward the transfer means.
[0008]
[Problems to be solved by the invention]
However, in such a conventional image forming apparatus, when the sheet P on the paper feed tray 56 is conveyed to the paper feed transfer conveyance path R1 by the paper feed means 51, the sheet conveyance by the paper feed means 51 indicated by an arrow in FIG. Since there is an angle α between the direction and the sheet transfer path R1, a large change in direction is required.
[0009]
Here, when such a large change of direction is performed, the leading end of the sheet P slides along the conveyance surface 60 of the sheet transfer transfer conveyance path R1, and the sheet P is greatly bent at the time of the change of direction. At the moment when the sheet P is detached from the sheet feeding means 51, the rigidity of the sheet P causes the rear end of the sheet P to largely jump, thereby generating noise. Further, the toner image being transferred by the transfer unit 52 may be disturbed by the vibration when the trailing edge of the sheet comes off.
[0010]
Further, when the sheet P such as a thick paper or an envelope is conveyed, if the sheet is bent to change the direction, the sheet P is likely to be defective due to the resistance due to the rigidity of the sheet P. In such a case, the feeding pressure of the feeding roller 51a and the feeding pressure of the feeding roller 57 may be set to a large value. When the sheet is fed, roller marks of the sheet feed roller 51a and the transport roller 57 may adhere to the sheet.
[0011]
Therefore, the present invention has been made in view of such a situation, and provides an image forming apparatus capable of forming a high-quality image while conveying a sheet quietly and stably. It is intended to do so.
[0012]
[Means for Solving the Problems]
The present invention is formed by a sheet storage unit that stores sheets, a sheet feeding unit that conveys the sheets stored in the sheet storage unit to an image forming unit provided in an image forming apparatus main body, and the image forming unit. A transfer unit that transfers the toner image to the sheet, a fixing unit that fixes the toner image transferred by the transfer unit to the sheet, and a transfer unit that is provided between the paper supply unit and the transfer unit, A first transport guide that guides the fed sheet to the transfer unit; and a second transport guide that is provided between the transfer unit and the fixing unit and guides the sheet on which the toner image has been transferred to the fixing unit. An image forming apparatus in which the sheet feeding unit, the transfer unit, and the fixing unit are arranged obliquely upward substantially in a straight line with the fixing unit being the uppermost part. The sheet conveyance direction of the means is substantially the same as the inclination angle of the first conveyance guide, and the substantially straight conveyance path which is formed by the first conveyance guide and the second conveyance guide and is inclined upward is formed by the image forming. It is characterized by being arranged so as to be parallel or coincident with the diagonal line of the apparatus main body.
[0017]
Further, in the invention, it is preferable that the sheet feeding unit includes a feeding unit that feeds out the sheet, and a separating member that is pressed against the feeding unit so as to separate the sheets one by one and arranged substantially in parallel with the first conveyance guide. And characterized in that:
[0018]
Further, the present invention is characterized in that a contact portion of the separation member with the feeding means has a curved surface.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0020]
FIG. 1 is a diagram showing a schematic configuration of an electrophotographic laser beam printer which is an example of an image forming apparatus according to a first embodiment of the present invention, and FIG. 2 is a perspective view thereof.
[0021]
1 and 2, reference numeral 100 denotes a laser beam printer. The laser beam printer 100 includes an image forming unit 101, a paper feeding unit 102 that feeds a recording material P, which is a sheet, to the image forming unit 101, The image forming apparatus includes a transfer unit 103 that transfers the toner image to the recording material P and a fixing unit 104 that fixes the toner image transferred to the sheet P to the sheet.
[0022]
Here, the paper supply unit 102 includes a paper supply tray 1 as a sheet storage unit on which the recording material P is stacked, a paper supply roller 2 as a paper supply unit disposed on an upper front end side of the paper supply tray 1, and a paper supply unit. And a sheet feeding means 2A having a separation pad 4 which is a separation member which is pressed against the roller 2.
[0023]
In FIG. 1, reference numeral 3 denotes a pressure plate which constitutes the front end of the recording material loading surface 1a of the sheet feeding tray 1 and is pressed upward by a biasing means (not shown). The front end of the recording material P stacked on the surface 1 a is in pressure contact with the paper feed roller 2.
[0024]
When the recording material P is pressed against the paper feeding roller 2 and the paper feeding roller 2 rotates, the uppermost recording material P is picked up by the paper feeding roller 2 and thereafter, the uppermost recording material P is picked up. The material P is separated and conveyed one by one from the other recording material P by the separation pad 4 and the sheet feeding roller 2, and is conveyed to the transfer unit 103 by a pair of conveying rollers 5 a and 5 b constituting a conveying unit. I have.
[0025]
Further, the image forming unit 101 exposes the surface of the photosensitive drum 10a by exposing the surface of the photosensitive drum 10a to the process cartridge 10 constituting an image forming unit including the photosensitive drum 10a, the developing unit 10b, the charging roller 10c, and a cleaner (not shown). And a laser scanner 7 for forming an electrostatic latent image on the photosensitive drum 10a. 7a is a polygon mirror, 7b is a scanner motor for rotating the polygon mirror 7a, and 8 is a return mirror.
[0026]
The transfer unit 103 forms a transfer nip by pressing against the photosensitive drum 10a, and transfers the toner image on the photosensitive drum 10a to the recording material P when the recording material P passes through the transfer nip. It is constituted by a transfer roller 11 as a means. The fixing unit 104 includes a fixing device 13 which is a fixing unit having a heating roller 13a and a pressure roller 13b pressed against the heating roller 13a.
[0027]
In FIG. 1, reference numeral 12a denotes a first conveyance guide, which is a guide member for guiding the recording material P separated and conveyed by the paper feeding means 2A to the transfer unit 103; A second conveyance guide 14 serving as another guide member for guiding the recording material P to the fixing device 13 is a paper discharge roller. The recording material P on which the toner image is fixed by the fixing device 13 is covered by a paper discharge roller 14. The paper is discharged onto a paper discharge tray 16 formed integrally with the paper discharge tray 15.
[0028]
In FIG. 2, reference numeral 6 denotes a registration sensor for detecting the leading end position of the recording material P, and control means (not shown) are a leading end position of the recording material P and an exposure light source based on a detection signal from the registration sensor 6. By synchronizing the light emission timing of the laser scanner 7, an image is drawn from a predetermined position on the recording material P. Reference numeral 17 denotes an electrical unit including an AC power supply, a DC power supply, and a high-voltage power supply, and reference numeral 18 denotes a motor as a driving source.
[0029]
Next, an image forming operation in the laser beam printer 100 thus configured will be described.
[0030]
When the image forming operation is started, first, the photosensitive drum 10a is uniformly charged to a predetermined polarity and a predetermined potential by the charging roller 10c. After the surface of the photosensitive drum 10a is charged in this way, the surface of the photosensitive drum 10a is subjected to image exposure based on the image information by the laser scanner 7, and as a result, the charge of the exposed portion is removed and the electrostatic latent image is removed. An image is formed. Next, the electrostatic latent image is developed by the developing device 10b, and a toner image is formed on the photosensitive drum.
[0031]
On the other hand, the recording material P stored in the paper feed tray 1 in parallel with such toner image forming operation is picked up by the paper feed roller 2 and then separated and conveyed by the separation pad 4 and the paper feed roller 2. Thereafter, the sheet is conveyed to the transfer nip between the photosensitive drum 10a and the transfer roller 11 along the first conveyance guide 12a by the pair of conveyance rollers 5a and 5b.
[0032]
At this time, the leading end of the recording material P is detected by the registration sensor 6, and the control unit synchronizes the light emitting timing of the laser scanner 7 with the leading end position of the recording material P based on the detection signal of the registration sensor 6. Thereby, the toner image formed on the photosensitive drum can be transferred to a predetermined position on the recording material P.
[0033]
Next, the recording material P on which the toner image has been transferred in this manner is conveyed along a second conveyance guide 12b to a fixing nip formed by a heating roller 13a and a pressure roller 13b that constitute the fixing device 13, and Here, the unfixed toner image is heated and pressed to be fixed on the recording material surface. The recording material P on which the toner image has been fixed in this manner is discharged onto a discharge tray 16 by a discharge roller 14.
[0034]
By the way, in the present embodiment, the sheet feeding unit 2A, the transfer unit 103 (transfer roller 11), and the fixing unit 104 (fixing unit 13) are obliquely arranged substantially in a straight line with the fixing unit 13 as the uppermost part as shown in FIG. It is arranged upward. Further, the recording material stacking surface 1a of the sheet feeding tray 1 and the first and second conveyance guides 12a and 12b for conveying the recording material P conveyed from the sheet feeding means 2A to the transfer rollers 11 to the fixing device 13 are provided above. The angle formed by the inclined and substantially straight conveyance path R is configured to be an obtuse angle.
[0035]
On the other hand, when the recording paper P stacked on the paper feed tray 1 is separated and conveyed by the paper feed roller 2 and the separation pad 4, the conveyance direction A is a substantially straight conveyance path R inclined upward as shown in FIG. Is set substantially equal to the angle of the first transport guide 12a. The separation pad 4 is arranged substantially parallel to the first conveyance guide 12a so that the recording material P can be conveyed in such a direction.
[0036]
Then, the recording material P is conveyed at substantially the same angle as the first conveyance guide 12a inclined upward as described above, so that the recording material P moves from the paper feed tray 1 to the conveyance path R (the first conveyance guide 12a). The direction change at the time can be made gentle.
[0037]
Accordingly, when the recording material P is conveyed toward the conveyance path R (the first conveyance guide 12a), the recording material P does not bend in the conveyance path R due to a change in direction. It is possible to prevent the sound of bouncing or the sound of the recording material P rubbing against the first transport guide 12a, and to reduce the paper feeding operation noise. Further, it is possible to prevent the trailing edge of the recording material P from coming off from the paper feed roller 2 and prevent the vibration when the direction is changed, and the transfer image is disturbed by the vibration of the recording material P when the transfer roller 11 transfers the toner image. Can also be prevented.
[0038]
In this way, the recording material P is conveyed along the first conveyance guide 12a at substantially the same angle as the angle of the first conveyance guide 12a inclined upward, and the direction change of the recording material P is moderated. Thus, the paper feeding operation noise can be reduced, and the disturbance of the transferred image can be prevented.
[0039]
Further, since the resistance of the recording material P due to the bending in the transport path R can be reduced, the recording material P such as a thick paper or an envelope can be stably fed even at a low feeding pressure or a low feeding pressure. Become. Thereby, a quiet and high-quality image can be formed, and an apparatus having high media flexibility can be provided.
[0040]
By the way, in FIG. 3 described above, the separation surface 4a of the separation pad 4 is shown as a plane, but the present invention is not limited to this. For example, as shown in FIG. May be a curved surface. By making the separation surface 4a of the separation pad 4 curved as described above, the nip N width between the sheet feeding roller 2 and the separation pad 4 can be increased, and the reliability of separation of the recording material P is improved. be able to.
[0041]
Further, by setting the separation surface 4a of the separation pad 4 to be a curved surface, the angle of the conveyance path R and the sheet feeding direction A of the recording material P by the sheet feeding roller 2 and the separation pad 4 are set to be substantially the same. 2 and the pressing plate 3, it is possible to reduce the entry angle β of the recording material P into the separation pad 4. Thereby, the direction of the recording material P from the sheet feeding tray 1 to the conveyance path R can be more favorably changed, and a device with a small sheet feeding operation sound, high image quality and stable sheet feeding performance can be provided. it can.
[0042]
On the other hand, as described above, the paper feeding unit 2A, the transfer roller 11, and the fixing device 13 are arranged almost linearly and obliquely upward with the fixing device 13 as an uppermost portion as shown in FIG. After the recording material P loaded on the tray 1 is fed by the feed roller 2, the recording material P is conveyed to the transfer unit 103 by the conveying roller pair 5a and 5b along the substantially straight conveyance path R, and then transferred to the photosensitive drum 10a. With the rollers 11, the toner image is nipped and conveyed to the fixing device 13 simultaneously with the transfer of the toner image.
[0043]
Here, the conveyance path R of the recording material P during this period is substantially straight, so that the sliding noise between the recording material P and the guide members 12a and 12b during the conveyance of the recording material P can be reduced, and the recording material P can be reduced. Can be stably conveyed, and the reliability of recording material conveyance can be improved.
[0044]
Further, since the fixing device 13 is disposed at the uppermost portion of the transport path R, even when the printing operation is continuously performed, the heat generated from the fixing device 13 is not generated by the heat generated by the fixing device 13 inside the outer cover 15 (not shown). It is discharged from the louver part to the outside of the device. Further, since the process cartridge 10 and the laser scanner 7 are disposed below or beside the fixing device 13, it is possible to always obtain a good output image without being affected by the heat generated from the fixing device 13. It becomes possible.
[0045]
Further, the transport path R is made substantially parallel or coincident with the diagonal line of the laser beam printer main body 100A. With such a configuration, various mechanisms can be effectively arranged, and the size of the apparatus can be reduced.
[0046]
Next, the arrangement of the laser scanner 7, the process cartridge 9, the electrical unit 17, and the motor 18 will be described as an example of an arrangement for miniaturizing such an apparatus.
[0047]
Here, in order to make the size of the laser beam printer 100 as small as possible, the laser beam printer 100 which is an example of the image forming apparatus according to the second embodiment of the present invention shown in FIGS. As described above, it is most effective that the laser beam is incident on the photosensitive drum 10a from a direction substantially perpendicular to the transport path R. With such a configuration, the depth and height of the laser beam printer 100 can be reduced to minimum dimensions.
[0048]
Therefore, the laser scanner 7 moves leftward or rightward from the polygon mirror 7a as shown in FIG. 1 or FIG. 5 so that laser light can be incident on the photosensitive drum 10a from a direction substantially perpendicular to the transport path R. Arrangement. With this arrangement, the scanner motor 7b for rotating the polygon mirror 7a is substantially horizontal, so that the load on the bearing of the scanner motor 7b is eliminated and the life of the scanner motor 7b is reduced due to the shaving of the bearing. This makes it possible to prevent the occurrence of problems such as shortening of the length, and allows the device to be used for a long period of time.
[0049]
Further, with the configuration shown in FIG. 1, the process cartridge 9 can be attached and detached substantially horizontally in the direction of the paper feed tray 1, and the jam processing in the image forming apparatus and the replacement of the process cartridge 9 are all performed from the same direction. And usability can be improved.
[0050]
In the case of the configuration shown in FIG. 5, the process cartridge 7 is attached and detached from above, but since the laser scanner 7 can be kept away from the fixing device 13, the influence of the temperature rise due to the heat of the fixing device 13 can be obtained. There is a merit that it can be hard to receive. If the setting of the laser beam incident angle is as shown in FIG. 1 or FIG. 5, a large degree of freedom is provided for the arrangement of the laser scanner 7, so that the problems of usability and temperature rise can be avoided. It will be easier.
[0051]
On the other hand, the electrical unit 17 composed of an AC power supply, a DC power supply, and a high-voltage power supply is disposed below the transport path R as shown in FIG. 1 or 5, and the space area in the electrical unit is increased from the sheet feeding unit 102 to the fixing unit 104. Configuration. Thereby, a path of an air flow generated by the heat generated from the electrical component unit 17 is secured.
[0052]
The heat generated from the fixing unit 13 disposed above the electrical unit 17 is discharged to the outside of the apparatus from the louver unit (not shown) provided on the exterior cover 15 as described above. At this time, by providing a space between the rear surface of the fixing device 13 and the exterior cover 15, it is possible to generate an airflow also at this portion due to the maturity of the fixing device 13.
[0053]
By providing a large space below the fixing unit 13 and arranging the electrical unit 17 and providing a space on the rear side of the fixing unit 13 as described above, even if there is no FAN or the like for cooling, the electrical unit 17 is provided. Thus, it is possible to generate an air flow for waste heat from the first to the fixing device 13, thereby eliminating the heat buildup inside the laser beam printer main body and preventing the temperature rise.
[0054]
As a result, it is possible to achieve a fan-less configuration and achieve a cost reduction. In addition, since there is no sound generated from the fan, it is possible to provide a quiet laser beam printer 100.
[0055]
In addition, in order to effectively use the space area below the transport path R, the electrical component 17 has an L-shaped layout including a horizontal portion and a vertical portion, so that the efficiency of the electrical component can be further increased. . Specifically, a component or element that is a heat source is arranged on the vertical surface side, and a component or element that does not generate heat relatively is arranged on the horizontal plane side. By laying out in this way, it is possible to more efficiently discharge waste heat from the electrical component unit 17.
[0056]
The motor 18 as a drive source is directly mounted inside a conductive side wall 19 which is a part of the frame of the laser beam printer 100 shown in FIG. 2, and is attached by screws. Further, the motor 18 is disposed below the transport path R, and by arranging the motor 18 at such a position, the size of the motor can be increased or the stepping motor can be transferred from the DC motor to the DC motor when the laser beam printer 100 is operated at high speed. It is possible to flexibly respond to changes and the like. As a result, it is possible to easily achieve a speed increase from, for example, 10 ppm to 20 ppm.
[0057]
Further, by directly mounting the motor 18 inside the conductive frame 19 of the laser beam printer 100, the heat generated by the motor itself can be easily dissipated to the entire frame, and the motor efficiency can be improved. In addition, it is easy to take the ground and the total cost can be reduced.
[0058]
By the way, in the present embodiment, as shown in FIG. 2, the frame configuration of the laser beam printer 100 includes a pair of conductive left and right side walls 19 and 20, a sheet feeding unit 2A, a pair of conveying rollers 5a and 5b, and a transfer roller. 11, a fixing plate 13, a transfer plate 21 made of resin for holding the first and second transfer guides 12a and 12b, a conductive scanner plate 22 for holding the laser scanner 7, and an electrical component 17, and a laser beam printer main body. It is composed of a conductive bottom plate 23 arranged at the bottom of 100A.
[0059]
Here, the right and left side walls 19 and 20 are made of a sheet metal because a conductive material is suitable from the viewpoint of rigidity, electric ground, and electromagnetic wave shielding. And, as described above, the motor 18 is directly mounted on the right side plate 19, and thus, great advantages are obtained from heat dissipation, vibration reduction, and ease of electric ground connection.
[0060]
In addition, the transport plate 21 having the main unit such as the paper feed unit 2A, the transport roller pairs 5a and 5b, and the first and second transport guides 12a and 12b is costly because a complicated shape is formed into one component. An integrally molded product made of a resin material is used because of its merit that heat can be insulated from the down and the electric component 17.
[0061]
Further, the scanner plate 22 needs to have high rigidity in order to reduce vibration caused by the rotation of the polygon mirror 7a, and uses a sheet metal material. The bottom plate 23 disposed at the lowermost portion of the apparatus is made of a sheet metal material because of its rigidity as a part of the structure and characteristics of an electromagnetic wave shield required for holding the electrical component 17.
[0062]
With the above-described frame configuration, there is an effect that low cost can be achieved while satisfying functions of heat insulation, high rigidity, heat radiation, and vibration reduction.
[0063]
【The invention's effect】
As described above, according to the present invention, when the sheet is conveyed to the guide member by the sheet feeding unit, the sheet conveying direction is set to the direction along the guide member. This makes it possible to eliminate the change in direction, thereby making it possible to convey the sheet quietly and stably, and to form a high-quality image.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a schematic configuration of a laser beam printer as an example of an image forming apparatus according to a first embodiment of the present invention.
FIG. 2 is a perspective view of the laser beam printer.
FIG. 3 is a diagram illustrating a configuration of a paper feeding unit of the laser beam printer.
FIG. 4 is a diagram showing another configuration of a paper feeding unit of the laser beam printer.
FIG. 5 is a diagram illustrating a schematic configuration of a laser beam printer as an example of an image forming apparatus according to a second embodiment of the present invention.
FIG. 6 is a diagram illustrating a schematic configuration of a laser beam printer as an example of a conventional image forming apparatus.
FIG. 7 is a diagram showing a schematic configuration of another conventional laser beam printer.
FIG. 8 is a diagram showing a configuration of a paper feeding unit of the conventional laser beam printer.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 paper feed tray 2A paper feed means 2 paper feed roller 3 pressure plate 4 separation pad 9 process cartridge 10a photosensitive drum 11 transfer roller 12a first transport guide 12b second transport guide 13 fixing device 100 laser beam printer 101 image forming section

Claims (3)

Sheet storing means for storing sheets, sheet feeding means for conveying the sheets stored in the sheet storing means to an image forming section provided in an image forming apparatus main body, and a toner image formed by the image forming section. A transfer unit that transfers the toner image transferred by the transfer unit to a sheet; a fixing unit that fixes the toner image onto the sheet; and a sheet that is provided between the paper supply unit and the transfer unit and is sent from the paper supply unit. A first transport guide that guides the sheet to the transfer unit, and a second transport guide that is provided between the transfer unit and the fixing unit and guides the sheet on which the toner image has been transferred to the fixing unit. An image forming apparatus in which the sheet feeding unit, the transfer unit, and the fixing unit are arranged obliquely upward substantially in a straight line with the fixing unit being an uppermost part ,
The sheet conveying direction of the sheet feeding means is substantially the same as the inclination angle of the first conveyance guide, and a substantially straight conveyance path inclined upward formed by the first conveyance guide and the second conveyance guide is formed by: An image forming apparatus, wherein the image forming apparatus is disposed so as to be parallel or coincident with a diagonal line of the image forming apparatus main body . The paper feeding means includes a feeding means for feeding out the sheets, and a separating member which is in pressure contact with the feeding means so as to separate the sheets one by one and arranged substantially in parallel with the first conveyance guide. The image forming apparatus according to claim 1, wherein: The image forming apparatus according to claim 2 , wherein a contact portion of the separation member with the feeding unit has a curved surface.

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