JP3988748B2 - Image forming apparatus - Google Patents

Description

The present invention relates to an image forming apparatus for forming an image on a recording medium, and more particularly, a plurality of pairs of scanner unit and the process unit further image forming apparatus having an image forming belt for conveying the recording medium About.

  Conventionally, an image forming belt for carrying a developer image or conveying a recording medium, a plurality of photosensitive drums provided for each color so as to face the image forming belt, and for each of the photosensitive drums A plurality of scanner units for exposing and scanning the surface of the photosensitive drum, each of which includes any one of the photosensitive drums, and an electrostatic latent image formed on the surface of the photosensitive drum by the exposure scanning, A plurality of process units that develop by attaching the developer of the corresponding color, and a developer image formed on the surface of each photoreceptor drum by each process unit, the image forming belt or the image forming belt And an image forming apparatus including a transfer unit that transfers the image to the recording medium conveyed by the printer.

  For example, when the image forming belt is a so-called intermediate transfer belt for carrying a developer, image formation is performed as follows. When each color scanner unit exposes and scans the photosensitive drum in accordance with the image data, the electrostatic latent image formed by the exposure scan is developed by attaching a corresponding color developer. This developer image is transferred to an intermediate transfer belt by a transfer means such as a primary transfer roller, and the developer images are transferred onto a recording medium after, for example, four color developer images are overlaid (for example, , See Patent Document 1).

Further, when the image forming belt is a so-called conveying belt that conveys a recording medium, for example, a four-color developer image is formed on the intermediate transfer belt by conveying the recording medium by the conveying belt. In the same manner as in the above, the developer images are directly superimposed on the recording medium, and an image is formed on the recording medium (see, for example, Patent Document 2).
JP 2003-173066 A JP-A-7-234622

  However, in the devices of each of the above-mentioned patent documents, process units are set up vertically on an image forming belt and arranged side by side in the depth direction (attachment / detachment direction of the paper feed cassette). For this reason, the height of the apparatus is increased and it is difficult to reduce the size. Further, when replacing all or part of the process unit, the entire or part of the process unit is pulled out and attached in the vertical direction, so that the replacement is difficult and the maintainability is not sufficient.

  Accordingly, the present invention has been made for the purpose of providing an image forming apparatus in which the entire apparatus can be easily miniaturized and the process unit can be easily maintained.

The present invention has been made in order to achieve the above object, an image forming belt for conveying the recording medium, a plurality of photosensitive drums provided for each color so as to face the belt the imaging, respective photosensitive A plurality of scanner units that are provided for each photosensitive drum and that expose and scan the surface of the photosensitive drum, each of which is one of the photosensitive drums, and electrostatic latent images formed on the surface of the photosensitive drum by the exposure scanning. an image, a plurality of process units to be developed by depositing the corresponding color developer, a developer image formed on each photosensitive drum surface by the respective process units belts for the image forming Therefore an image forming apparatus comprising a transfer unit that transfers to the recording medium conveyed, and below the imaging belt, a cassette for holding the recording medium With the possible out come, said imaging belt, so the transport direction downstream side of the recording medium decreases, and is disposed to be inclined to be higher toward the drawing direction of the cassette, each scanner A tray for discharging the recording medium after image formation is disposed above the unit and each process unit, and the tray is inclined in the same direction as the image forming belt, and each scanner with unit and the process units are arranged alternately in the depth direction along the tray underneath the tray, each of the scanner unit and the process units is obliquely with respect to the vertical direction, of the cassette is arranged to be inclined to the pulling direction, detachable at least part of the respective process units along a direction inclined to said first diagonal, it said And upper portions and the respective process units of the scanner unit is characterized in that it is arranged substantially parallel to the inclination direction of the imaging belt.

  In the present invention configured as described above, since the scanner unit and the process unit provided for each color are arranged obliquely, the height of the apparatus can be suppressed. Further, the depth of the apparatus needs to be larger than the depth in which the scanner unit and the process unit are arranged vertically because it is necessary to provide a recording medium conveyance system and the like. For this reason, even if the scanner unit and the process unit are arranged obliquely, the depth does not increase that much.

Therefore, in the present invention, the apparatus can be favorably downsized. Further, in the present invention, since at least a part of the process unit can be attached / detached obliquely, the attachment / detachment is facilitated, and the maintenance performance relating to the replacement of the photosensitive drum or the replenishment of developer is improved. Further, in the present invention, the image forming belt is inclined and disposed so that the downstream side in the conveyance direction of the recording medium is lowered, and the recording medium after image formation is disposed above each scanner unit and each process unit. A tray for discharging is provided, and the tray is inclined in the same direction as the image forming belt. In addition, the scanner units and the process units are alternately arranged in the depth direction along the tray below the tray. For this reason, the upper ends of the scanner unit and the process unit can be arranged along the tray, and a space with a certain width can be secured on the back surface of the tray. Therefore, in the present invention, it is possible to satisfactorily downsize the apparatus while ensuring the air permeability in the vicinity of the upper end of the process unit. Further, in the present invention, the depth of the apparatus can be shortened by arranging the image forming belt at an inclination.

In the present invention, below the upper Symbol imaging belt comprising drawably the cassette for holding the recording medium, each of the scanner unit and the process units are inclined in the drawing direction of the cassette Therefore , the following additional effects are produced.

  That is, in this type of image forming apparatus, the cassette is pulled out and the recording medium is replenished. However, since the photosensitive drum can be replaced or the developer can be replenished from the same direction, maintenance is further improved. improves.

  Further, when a cover that covers each process unit so as to be openable and closable from above is provided independently for each process unit, the following further effects are produced. In this case, since only the cover corresponding to the process unit requiring maintenance needs to be opened and closed, the operation becomes easier and the maintainability is further improved as compared with the case where the large cover covering all the process units is opened and closed.

Further, in the present invention, the imaging belt, because it is disposed inclined to become higher toward the drawing direction of the cassette, additional effects such as the following may occur. That is , the depth of the apparatus can be shortened by disposing the image forming belt in an inclined manner, and further, the recording medium conveyance system or the like in the space formed above and below by inclining the image forming belt. By providing this, the apparatus can be further miniaturized.

In this case, when the imaging belt is arranged inclined to become higher toward the drawing direction of the upper Symbol cassette, in particular the following effects can occur. In this case, since the upstream side of the image forming belt is disposed at a high position and a large space is formed below the belt, a transport system (such as a pickup roller) for transporting the recording medium to the image forming belt is provided in the space. And the device can be further miniaturized.

Further, in the present invention, the upper portion of the upper and the respective process units of each scanner unit, since it is arranged substantially parallel to the inclination direction of the imaging belt, occurs further the following effects . That is , the height of the scanner unit and the height of the process unit can be made uniform, and the apparatus can be further miniaturized. Here, “substantially parallel” means that the width is assumed assuming that it is difficult to uniquely define the geometric position of the “upper part” due to the design constraints of the scanner unit and process unit. For example, it is only necessary that a line segment connecting appropriately selected points on the upper end surfaces of the scanner unit and the process unit is parallel to the inclination direction of the image forming belt.

  In the present invention, each photosensitive drum is rotatably arranged near the lower end of each process unit, and the scanner unit exposes and scans the photosensitive drum from the vicinity of the upper end of the scanner unit. When adopted, the following additional effects are produced. In this case, since exposure scanning is performed from the vicinity of the upper end of the scanner unit toward the photosensitive drum near the lower end of the process unit, the optical path of the exposure scanning becomes long, and the scanner unit can be miniaturized by miniaturizing the lens. Is possible. Further, since exposure scanning is performed from a position away from the photosensitive drum, it is possible to prevent the optical element from being soiled by a developer or the like. Therefore, it is possible to further reduce the size of the apparatus and form a clearer image.

  In the present invention, the width of each scanner unit in the direction alternately arranged with each process unit is configured to be narrow in the vicinity of the upper end of each scanner unit. When the width of each of the process units is configured to expand toward the narrow width portion of the scanner unit in the vicinity of the upper end of each of the process units, the following further effects are produced. In this case, the amount of developer that can be accommodated in the process unit can be increased, the frequency of developer replenishment can be reduced, and the maintainability can be further improved.

  Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal sectional view showing the overall configuration of a color laser printer as an embodiment of the present invention. As shown in FIG. 1, the color laser printer according to the present embodiment includes a paper feed cassette 3 that is detachably inserted below a main body frame 1 as a housing. That is, the paper feed cassette 3 can be pulled out from the storage position indicated by the solid line in FIG. 1 toward the pulling position indicated by the two-dot chain line, and the recording paper P can be replenished appropriately in this state.

  A support plate 5 urged upward by a spring (not shown) is provided inside the paper feed cassette 3, and further above the support plate 5, recording paper held in a stacked manner on the support plate 5. A pair of paper feed rollers 8 and 9 for separating P one by one and supplying them in the directions of image forming units 7M, 7Y, 7C and 7B described later are provided. The sheet feeding roller 8 on the left side in the drawing conveys the uppermost recording sheet P toward the sheet feeding roller 9, and the sheet feeding roller 9 on the right side in the figure is pressed against the separation pad 10 to feed one sheet of recording sheet P. This is a so-called pick-up roller that separates and conveys them one by one.

  Each of the rollers including the paper feed rollers 8 and 9 is rotatably provided at a predetermined position of the main body frame 1 and is driven by a driving source common to the image forming units 7M, 7Y, 7C, and 7B. On the other hand, the separation pad 10 is provided in the paper feed cassette 3 via the spring 11, and is pressed against the paper feed roller 9 by the elastic force of the spring 11 when the paper feed cassette 3 is inserted to a predetermined position.

  Image forming units 7M, 7Y, 7C, and 7B for forming images corresponding to the colors magenta, yellow, cyan, and black slightly above the center of the main body frame 1 (hereinafter, when the color needs to be specified) Other than the above, the subscripts of M, Y, C, and B are omitted). In the conveyance path of the recording paper P from the paper supply roller 9 to the image forming unit 7, the pair of conveying rollers 13 that convey the recording paper P and the image forming unit 7 temporarily stop before the image forming operation. A registration roller 15 that sequentially feeds the recording paper P to the image forming unit 7 after correcting the skew of the recording paper P by locking the leading end of the recording paper P is sequentially disposed.

  A belt 16 that conveys the recording paper P that has passed through the registration roller 15 is disposed at a portion that faces the four image forming units 7. A toner image of each color is formed by the forming unit 7. A paper feed port 17 for manually feeding the recording paper P is provided below the main body frame 1 on the drawer side (hereinafter referred to as the front side) of the paper feed cassette 3. The recording sheet P fed from here is conveyed to the nip portion of the registration roller 15 by the manual sheet feeding roller 18, and then an image is formed while being conveyed by the belt 16 as described above.

  Next, each image forming unit 7 includes a scanner unit 21 and a process cartridge 31. The scanner unit 21 reflects a laser beam L generated by a laser diode (not shown) so as to sequentially change the direction along a predetermined surface, and the laser beam L reflected by the polygon mirror 22 is reflected on the process cartridge 31. A folding mirror 23 that turns back toward the photosensitive drum 33 and an fθ lens 24 provided in the optical path of the laser beam L are housed in a housing 26.

  The housing 26 is provided with an exposure opening 26a on the process cartridge 31 side so that the folded laser beam L reaches the photosensitive drum 33. The folding mirror 23 is provided in the vicinity of the upper end of the process cartridge 31, and is folded back from the exposure opening 26a so that the angle formed by the laser beam L before folding and the laser beam L after folding is about 15 °. Exit.

  For this reason, the scanner unit 21 and the process cartridge 31 can be arranged close to each other to reduce the size of the entire apparatus. Further, since the laser beam L is exposed and scanned from the vicinity of the upper end of the scanner unit 21 toward the photosensitive drum 33, a sufficient optical path can be secured, and the fθ lens 24 and the like can be downsized to further reduce the size of the apparatus. Can be realized. Further, since the laser beam L is exposed and scanned from the vicinity of the upper end of the scanner unit 21, the exposure opening 26a is also disposed above the center of the scanner unit 21, and an optical element such as a protective glass covering the exposure opening 26a is used as the toner. It is also possible to prevent contamination.

  Further, the process cartridge 31 includes a photosensitive drum 33 having a photosensitive layer on its surface in a rotatable manner, and further includes a scorotron charger 34 that uniformly charges the surface of the photosensitive drum 33. A toner box 35 is provided above the photosensitive drum 33, and toner is supplied to the surface of the photosensitive drum 33 by the operation of a supply roller 37 and a developing roller 38 provided below the toner box 35. The

  With this configuration, an electrostatic latent image is formed on the surface of the photosensitive drum 33 by the laser light L from the scanner unit 21, and then the developing roller 38 supplies toner to the surface of the photosensitive drum 33. The electrostatic latent image is developed. Further, the photosensitive drum 33 faces the transfer roller 39 with the belt 16 interposed therebetween. Therefore, the toner obtained by developing the electrostatic latent image on the photosensitive drum 33 as described above receives the bias voltage applied from the transfer roller 39 and is transferred to the recording paper P conveyed on the belt 16. As a result, magenta, yellow, cyan and black images are sequentially formed on the recording paper P.

  The recording paper P that has passed through each image forming unit 7 is supplied to the fixing unit 41. In the fixing unit 41, the toner image formed on the recording paper P is sandwiched between the heating roller 43 and the pressing roller 45 and thermally fixed. The recording paper P on which the image is fixed is further conveyed by a pair of paper discharge rollers 51 and is discharged to a paper discharge tray 52 provided on the upper surface of the main body frame 1. Further, the cleaning roller 53 is in contact with the lower surface of the belt 16 to collect the toner that has ridden on the surface of the belt 16 due to scattering from the photosensitive drum 33 or the like.

  Next, the entire discharge tray 52 is configured to be openable and closable around a hinge 52a provided below the discharge roller 51, and the discharge tray 52 is rotated upward to open as shown in FIG. As shown, the process cartridge 31 can be attached to and detached from the photosensitive drum 33 integrally. In FIG. 2, the support plate 5 and the like are omitted.

  Here, in the color laser printer according to the present embodiment, the scanner units 21 and the process cartridges 31 are alternately disposed, and they are disposed so as to be inclined so that the upper ends thereof are inclined in the front direction. For this reason, it is possible to reduce the size of the apparatus while suppressing the height. The depth of the color laser printer (the length in the direction in which the paper feed cassette 3 is attached / detached) is greater than the depth in which the scanner unit 21 and the process cartridge 31 are arranged vertically because of the need to dispose various rollers as described above. It is necessary to take big. For this reason, even if the scanner unit 21 and the process cartridge 31 are disposed obliquely as described above, the depth does not increase that much.

  Further, since the process cartridge 31 is attachable / detachable along the direction inclined in the front direction (the direction indicated by the arrow A in FIG. 2) as described above, the process cartridge 31 is easily attached / detached. In addition, in the present embodiment, the replenishment of the recording paper P to the paper feeding cassette 3 and the removal of the recording paper P from the paper discharge tray 52 can be performed from the front side as in the case of attaching and detaching the process cartridge 31. The operability is greatly improved.

  In addition, in the present embodiment, the belt 16 is disposed so as to be inclined so that the front side is higher (that is, the downstream side in the toner transfer direction is lowered). For this reason, a wide space is formed below the front side of the belt 16, and the paper feed rollers 8, 9 and the like can be disposed there as described above. Further, the arrangement of the belt 16 inclined obliquely itself contributes to shortening the depth of the apparatus. Therefore, in this embodiment, the apparatus can be further downsized. Further, both the inclination direction of the belt 16 and the inclination direction of the process cartridge 31 are inclined in the direction of forming a space on the downstream side of the photosensitive drum 33. For this reason, a relatively large scorotron charger 34 can be easily disposed without increasing the size of the apparatus.

  Furthermore, in the present embodiment, the apparatus can be further miniaturized by aligning the height of the scanner unit 21 and the height of the process cartridge 31, and the paper discharge tray 52 is also disposed substantially parallel to the belt 16. The apparatus can be further miniaturized and an air flow having a constant width can be formed on the upper part of the process cartridge 31. For this reason, exhaust heat can also be performed satisfactorily.

  In the present embodiment, the folding mirror 23 is provided in the vicinity of the upper end of the scanner unit 21, thereby ensuring the optical path length and reducing the size of the scanner unit 21 itself. In addition, with this configuration, the casing 26 is configured such that the vicinity of the upper end of the scanner unit 21 is narrowed in the depth direction, and the toner box 35 is spread to the scanner unit 21 side accordingly. For this reason, it is possible to further increase the maintainability by increasing the amount of toner that can be stored in the toner box 35 without increasing the size of the apparatus and reducing the number of replacements. Therefore, in the color laser printer of this embodiment, the apparatus can be reduced in size and the maintainability can be improved.

  In the above embodiment, the toner is supplied to the developer, the recording paper P is to be recorded, the belt 16 is to the image forming belt, the process cartridge 31 is to the process unit, and the transfer roller 39 is to the transfer unit. The cassette 3 corresponds to a cassette, and the paper discharge tray 52 corresponds to a tray and a cover.

  In addition, the present invention is not limited to the above-described embodiment, and can be implemented in various forms without departing from the gist of the present invention. For example, in the above embodiment, the paper discharge tray 52 is provided so as to be openable and closable so as to cover the entire image forming units 7M to 7B. However, like the paper discharge tray 152 shown in FIG. It may be provided independently for each of 7M to 7B, and may be individually opened and closed around the hinge 152a. In this case, since it is only necessary to open and close only the paper discharge tray 152 corresponding to the process cartridge 31 requiring maintenance, the work becomes easier and the maintenance performance becomes easier than opening and closing the large paper discharge tray 52 as described above. improves.

Further, in the above embodiments, Magenta, yellow, cyan, an example of transferring the four color toners of black, magenta, yellow, may be three colors of cyan, just two-color printing There may be. In each of the above embodiments, the photosensitive drum 33 and the toner box 35 are replaced as an integral process cartridge 31, but only the toner box 35 may be replaceable.

1 is a longitudinal sectional view illustrating an overall configuration of a color laser printer to which the present invention is applied. It is explanatory drawing showing replacement | exchange of the process cartridge in the color laser printer. It is a longitudinal cross-sectional view showing the whole structure of the modification of the color laser printer.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Main body frame 3 ... Paper feed cassette 7 ... Image formation part 8, 9 ... Paper feed roller 16 ... Belt 21 ... Scanner unit 22 ... Polygon mirror 23 ... Folding mirror 24 ... f (theta) lens 26 ... Case 26a ... Exposure opening 31 ... Process cartridge 33 ... Photosensitive drum 39 ... Transfer roller 52 ... Discharge tray L ... Laser beam P ... Recording paper

Claims (4)

An image forming belt for conveying a recording medium;
A plurality of photosensitive drums provided for each color so as to face the image forming belt;
A plurality of scanner units provided for each of the photosensitive drums, for exposing and scanning the surface of the photosensitive drum;
A plurality of process units each including any one of the photosensitive drums and developing the electrostatic latent image formed by the exposure scanning on the surface of the photosensitive drum by attaching the developer of the corresponding color; ,
A transfer unit that transfers the developer image formed on each photosensitive drum surface to the recording medium is thus conveyed to the belts for the image formed by the respective process units,
In an image forming apparatus comprising:
Under the image forming belt, a cassette for holding the recording medium can be pulled out,
The image forming belt is disposed so as to incline so that the downstream side in the conveyance direction of the recording medium is lowered and becomes higher in the drawing direction of the cassette ,
A tray for discharging the recording medium after image formation is disposed above each scanner unit and each process unit, and the tray is inclined in the same direction as the image forming belt,
The scanner units and the process units are alternately arranged in the depth direction along the tray below the tray, and the scanner units and the process units are inclined with respect to the vertical direction . It is arranged to be inclined in the drawer direction of the cassette, and at least a part of each process unit is detachable along the obliquely inclined direction ,
An image forming apparatus, wherein an upper part of each scanner unit and an upper part of each process unit are disposed substantially parallel to the inclination direction of the image forming belt . The image forming apparatus according to claim 1 , wherein a cover that covers each process unit so as to be openable and closable from above is provided independently for each process unit . 2. The photosensitive drum is rotatably disposed in the vicinity of the lower end of each of the process units, and the scanner unit exposes and scans the photosensitive drum from the vicinity of the upper end of the scanner unit. Or the image forming apparatus according to 2; A width of each scanner unit in a direction alternately arranged with each process unit is configured to be narrow in the vicinity of an upper end of each scanner unit, and a width in each direction of each process unit is The image forming apparatus according to claim 1, wherein the image forming apparatus is configured to spread toward a narrow portion of the scanner unit near an upper end of the process unit .

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