JP4186948B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus such as a facsimile machine, a copying machine, or a printer (including these multifunction machines), and more specifically, a sheet is fed to an image recording unit through a sheet conveyance path rising from a sheet feeding unit in a substantially vertical direction. The present invention relates to an image forming apparatus configured to feed and sequentially record images on the feeding paper.

  As the image forming apparatus as described above, a pair of conveyance rollers (registration roller pair) arranged in the middle of a sheet conveyance path, feeding out sheets (recording sheets) one by one from a sheet feeding unit provided with a sheet cassette or the like. After that, the toner image on the surface of the photosensitive drum is transferred to a recording paper, fixed as a permanent image by a fixing device, and then discharged. And an electrophotographic image recording unit. Recently, in order to reduce the size of the device, the paper conveyance path from the paper feeding unit to the recording unit is raised substantially vertically, and after recording, the paper is discharged to a discharge tray located at the top of the device so as to make a U-turn. Many layouts have been adopted.

In order to increase the functionality of the apparatus, the paper that has passed through the recording unit is reversed before being discharged, merged with the paper conveyance path through the reverse paper conveyance path, and fed again to the recording unit. It is also possible to use a layout configuration in which recording is possible, or a manual sheet feeding unit is provided and a manual sheet feeding path from the manual sheet feeding unit is merged with the sheet feeding path. . On the other hand, in the case of the electrophotographic image recording unit as described above, if the paper dust adhering to the paper is transferred to the surface of the photosensitive drum or mixed into the developing device, it may cause a decrease in image recording quality. In addition, paper dust removing means has been provided upstream of the image recording unit. In Patent Document 1, a scraper for removing paper dust is brought into contact with an upstream conveying roller of an image recording unit (image forming means), and further, the paper dust removed and accumulated does not spill out even if the apparatus is tilted. Thus, a paper dust removing mechanism provided with a fall prevention film is disclosed.
JP 62-279381 A

  By the way, as described above, the main sheet conveyance path from the sheet feeding unit to the recording unit is raised substantially vertically so that the sheet after recording is U-turned and discharged to a discharge tray located at the top of the apparatus. In the image forming apparatus configured to join the main sheet conveyance path with the reversal sheet conveyance path and the manual sheet conveyance path for double-sided recording, these separate sheet conveyance paths (reversal conveyance path or manual sheet conveyance) The road) has a structure in which it merges upward in the middle of the main paper conveyance path via the downward curved portion.

  Therefore, the paper powder released from the paper being conveyed through the main paper conveyance path easily falls and accumulates in the downward curved portion, and the accumulated paper powder is conveyed through the paper conveyance path of the other path. The sheet is lifted by the sheet, and a part of the sheet is introduced together with the sheet to the mating portion between the photosensitive drum and the transfer roller through the main sheet conveyance path. The paper dust introduced into the mating part adheres to the surface of the photosensitive drum and affects the image recording quality as described above. In particular, in a positively charged electrophotographic recording unit, since paper is easily negatively charged, paper dust is electrostatically strongly attracted to the photosensitive drum, which may be a major cause of the above-described deterioration in image recording quality.

  In the paper dust removing mechanism disclosed in Patent Document 1, the paper dust removing scraper is brought into contact with the upstream conveying roller of the image recording unit, and the paper dust adhering to the conveying roller is scraped off and removed. However, since the scraper is brought into contact with the transport roller in a counter manner, there is a concern that a load is applied to the transport roller and the roller surface is easily damaged. Moreover, it is not intended to be applied to an image forming apparatus having a layout configuration in which another sheet conveyance path joins a sheet conveyance path that rises in a substantially vertical direction from the sheet feeding unit. There is no suggestion that the paper conveyance path to the recording unit may be targeted.

  The present invention has been made in view of the above circumstances, and the paper dust in the image forming apparatus having a layout configuration in which the paper transport path of another path joins the paper transport path rising in the substantially vertical direction from the paper feeding unit. An object of the present invention is to provide a novel image forming apparatus that can be easily removed.

An image forming apparatus according to a first aspect of the present invention feeds a sheet to an image recording unit through a main sheet conveyance path rising from a sheet feeding unit in a substantially vertical direction, and sequentially records images on the fed sheet. a is, in the middle of said main sheet transport path, the paper conveyance path to another path is formed confluent part for merging upwardly through the downward curved portion and the lower portion of the merging portion is paper dust accommodating section A flexible film is installed on the guide wall of the main paper transport path at each end where it is installed and joins the part that joins the main paper transport path from the paper feed section and the main paper transport path of the separate path. When the leading edge of the recording paper fed to the main paper conveyance path comes into contact with the film, the film always closes the opening to each junction with the main paper conveyance path. It is configured to be deformed and opened by pressure and to allow passage of recording paper .

  In the present invention, the paper transport path of the other path is a reverse paper transport path for reversing the paper that has passed through the image recording section and feeding it again to the image recording section, as in the invention of claim 2. Alternatively, a manual paper feed path from the manual paper feed unit can be used. Further, the image recording unit may be a positively charged electrophotographic recording unit as in the invention of claim 3.

  In the image forming apparatus according to the first aspect of the invention, since the paper dust container is installed below the junction between the main paper conveyance path rising in the substantially vertical direction and the paper conveyance path of another path, the main paper Most of the paper dust released from the paper transported on the transport path falls by its own weight, is stored in the paper powder storage section as it is, and is less likely to accumulate in the downward curved section in the paper transport path of another path. Therefore, the paper dust accumulated as described above is lifted by the paper conveyed through the downward curved portion, and is not transferred or introduced from the main paper conveyance path to the image recording unit. The adverse effect on image quality can be greatly reduced.

  According to the second aspect of the present invention, if the paper transport path of the different path is a reversal paper transport path and / or a manual paper transport path, the paper is raised from the paper feed unit in a substantially vertical direction and image recording is performed. In the image forming apparatus whose basic configuration is directed to the image forming unit, it is necessary to consider the influence of the paper dust as described above even when the multi-functionality is added by adding functions such as double-sided recording and manual sheet feeding. The degree of freedom of design is improved. In particular, as in the invention of claim 3, when an electrophotographic recording portion of a positive charging system in which paper dust is easily attracted to the photoreceptor as an image recording portion, such characteristics are extremely useful, This greatly contributes to the adoption and popularization of the positively charged electrophotographic recording unit in the image forming apparatus having the above basic configuration.

  The best mode for carrying out the present invention will be described below with reference to the drawings. FIG. 1 is a longitudinal sectional view showing an example of the image forming apparatus of the present invention, and FIG. 2 is an enlarged view of the main part.

  The image forming apparatus A shown in FIG. 1 is illustrated by taking a printer having an electrophotographic recording unit as an example. However, the image forming apparatus A is not limited to this, and is not limited to this. Needless to say, it may be a so-called multifunction machine or the like. In the figure, the apparatus main body 1 of the image forming apparatus A includes a recording paper (paper) feeding unit 2, an electrophotographic image recording unit 3, and a printed recording paper discharging unit 4 in this order. Layered in the height direction and configured. The recording paper feeding unit 2 includes a detachable paper feeding cassette 2a capable of accumulating and storing a large number of recording papers, a separation paper feeding roller 2b installed at the front end of the paper feeding cassette 2a, and the separation feeding paper. The separation pad 2c is in elastic contact with the peripheral surface of the paper roller 2b.

  The image recording unit 3 is a process in which a positive charging type charger 31, an exposure unit 32 made up of an LED, a developing unit 33, a transfer roller 34, and a foreign matter removal cleaner 35 are arranged in this order around the photosensitive drum 30. And a fixing device 36 on the downstream side thereof. These process units are collectively unitized as process units except for the exposure unit 32 and the transfer roller 34. However, the drum unit and the development unit are separated and can be individually attached to and detached from the apparatus main body 1. It is also possible to configure as described above. In addition to the case where these process units can be inserted and removed in the direction perpendicular to the paper surface in FIG. 1, there are cases where these process units can be taken out above the apparatus main body 1.

  On the downstream side of the fixing device 36, a switching gate 4a, a discharge roller pair 4b, and a discharge tray 4c are connected in series, and the discharge unit 4 is configured by these. A registration roller pair 5 is disposed in the vicinity of the upstream side of the process section, and the recording paper (paper) separated and fed from the paper feed cassette 2a one by one by the action of the separation paper feed roller 2b and the separation pad 2c. Is registered by the registration roller pair 5 and introduced into the mating portion between the photosensitive drum 30 and the transfer roller 34. The surface of the photosensitive drum 30 is positively charged by the charger 31 while rotating in the direction of the arrow in FIG. 1, and an optical image based on the image information is irradiated to the surface of the photosensitive drum 30 by the exposure device 32. An electrostatic latent image is formed on the surface of the photosensitive drum 30. The electrostatic latent image is sequentially developed by the developing device 33 and reaches a paired portion with the transfer roller 34 as a toner image. The registration roller pair 5 is synchronized with the toner image on the surface of the photosensitive drum 30. The recording paper is rotationally driven under registration control so as to be introduced into the mating portion.

  A bias is applied to the transfer roller 34, and the recording paper is nip-conveyed while being paired with the photosensitive drum 30 and being rotationally driven in the direction indicated by the arrow (with respect to the photosensitive drum 30). The toner image is transferred to the recording paper. The recording paper onto which the toner image has been transferred is introduced into the fixing device 36 and fixed as a permanent image, and then the switching gate 4a is pushed up and discharged onto the discharge tray 4c through the discharge roller pair 4b. This series of recording paper feeding includes a main paper conveyance path 6 that rises substantially vertically (vertically) immediately after feeding out from the paper feeding cassette 2a, and is substantially the same as the feeding direction from the paper feeding cassette 2a in the discharge roller pair 4b. It is made along a feeding path P (shown by a one-dot chain line in FIG. 1) that makes a U-turn in the direction of 180 degrees.

  The image forming apparatus A shown in the figure has a double-sided recording function, and circulates and joins the main paper conveyance path 6 upstream of the registration roller pair 5 from the attachment position of the switching gate 4a of the feeding path P. A reverse paper conveyance path 7 is formed. The upstream side of the merging portion 6a with the main sheet conveying path 6 of the reversing sheet conveying path 7 is a downward curved section 7c, and the merging section 6a merges upwardly to pass through a series of these reversing sheet conveying paths 7. Double-sided recording is possible. That is, the discharge roller pair 4b can be rotated forward and backward, and the reversing paper transport path 7 is provided with transport roller pairs 7a and 7b. When performing double-sided recording, single-sided recording is performed as described above. When the recorded sheet is conveyed along the feeding path P and the trailing edge of the recording sheet reaches the discharge roller pair 4b, the discharge roller pair 4b temporarily stops and nips the trailing edge of the recording sheet. Next, the discharge roller pair 4b is reversed, and the recording paper is conveyed from the rear end thereof by the conveyance roller pair 7a, 7b through the reverse sheet conveyance path 7, and passes from the merging section 6a to the main sheet conveyance path 6 via the downward curved portion 7c. Merge and reach the registration roller pair 5. It is registered by the registration roller pair 5 and is again introduced into the mating portion between the photosensitive drum 30 and the transfer roller 34 to record the back surface thereof. The recording paper on which both sides are recorded is then discharged onto the discharge tray 4c along the feeding path P as described above.

  The image forming apparatus A shown in the figure is further provided with a manual sheet feeding function, and a manual tray 8 that can be opened and closed vertically is attached to the side of the apparatus body 1. When not in use, the manual feed tray 8 is closed as indicated by a two-dot chain line in FIG. 1, and can be opened and closed by a handle 8a. A separation paper feed roller 8b and a separation pad 8c are arranged in a resilient contact state at the front end of the manual feed tray 8, and a manual paper feed path 9 that joins the main paper feed path 6 is further downstream. It is installed continuously. The upstream side vicinity of the junction 6b of the manual sheet conveyance path 9 with the main sheet conveyance path 6 is a downward curved portion 9a, and merges upward at the junction 6b.

  When recording an image using the manual feed tray 8, the handle 8a is opened to open the manual feed tray 8, a recording paper is set on the manual feed tray 8, and the manual feed roller 8b is actuated by an appropriate start operation. . The recording paper on the manual feed tray 8 is separated and fed out one by one by the action of the separation paper feed roller 8b and the separation pad 8c, conveyed through the manual paper conveyance path 9, and merges through the downward curved portion 9a. The unit 6b joins the main paper transport path 6. Thereafter, the image is registered by the registration roller pair 5 and is introduced into a mating portion between the photosensitive drum 30 and the transfer roller 34 to perform recording. When double-sided recording is performed on manual feed recording paper, the recording paper is transported through the reverse paper transporting path 7 by the reverse rotation of the discharge roller pair 4b, and the back side recording is performed as described above. The recording paper on which recording has been completed is discharged onto the discharge tray 4c by the discharge roller pair 4b.

  A paper dust container (paper dust container) 10 is detachably installed below the junctions 6a and 6b, and the paper dust released from the recording paper conveyed through the main paper conveyance path 6 rising substantially vertically is as follows. The paper dust container 10 is dropped by its own weight and stored in the paper powder container 10. Accordingly, paper dust is less likely to accumulate in the downward curved portion 7 c of the reverse paper conveyance path 7 or the downward curved portion 9 a of the manual paper conveyance path 9. Since the paper dust container 10 is detachable, it is convenient that it can be taken out when the paper dust becomes full and can be returned to its original position after the paper dust is discarded, but excludes fixed ones. It is not a thing.

  In the image forming apparatus A shown in the figure, a portion where the recording paper feeding unit 2d from the paper feed cassette 2a joins the main paper transport path 6, a joining part 6a of the reverse paper transport path 7 with the main paper transport path 6, and Flexible films 2 e, 7 d, and 9 b are attached to the guide wall of the main paper conveyance path 6 at each junction 6 b of the manual paper conveyance path 9 with the main paper conveyance path 6. . These films 2e, 7d, and 9b normally close the opening to each merging portion with the main paper transport path 6, and when the leading edge of the recording paper fed to the main paper transport path 6 comes into contact, It is deformed and opened as shown by a two-dot chain line in FIG. 2 by contact pressure to allow the recording paper to pass. Accordingly, the films 2e, 7d and 9b prevent the recording paper from erroneously entering the other conveyance path and the like, and the paper feeding unit 2d and the downward curved part of the paper powder falling in the main sheet conveyance path 6 7c and 9a are also prevented from entering.

  As described above, the paper dust released from the recording paper transported in the main paper transport path 6 rising in the substantially vertical direction is dropped and stored in the paper powder storage container 10, and thus the downward curve of the reversing paper transport path 7. The accumulation in the downward curved portion 9a of the portion 7c or the manual paper feed path 9 is reduced. Accordingly, the recording paper transported through the reverse paper transport path 7 or the manual paper transport path 9 is less likely to lift and transport the accumulated paper dust and is introduced into the mating portion between the photosensitive drum 30 and the transfer roller 34. As a result, the amount of paper dust is greatly reduced, and there is less concern that the quality of the recorded image will deteriorate. This embodiment is particularly effective when the electrophotographic recording unit 3 is a positive charging system as in this embodiment, and greatly contributes to the spread of the positive charging type electrophotographic recording apparatus.

  In the above embodiment, an example in which the image forming apparatus A is a single cassette type printer has been described. However, a multi-cassette type printer is not excluded, and an optional cassette is further provided below the recording paper cassette 2a in FIG. Etc. may be stacked. Further, the example in which the paper transport path of another path is the reverse paper transport path 7 or the manual paper transport path 9 has been described, but the main paper transport path 6 rising in a substantially vertical direction passes through the downward curved portion. Needless to say, the present invention can also be applied to an image forming apparatus provided with another sheet conveyance path that joins upward.

1 is a longitudinal sectional view illustrating an example of an image forming apparatus of the present invention. It is an enlarged view of the principal part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Apparatus main body 2 Paper feed part 3 Electrophotographic recording part (image recording part) of a plus charge system
6 Main paper transport path 6a Merging section 6b Merging section 7 Reverse paper transport path (paper transport path of another path)
7c Downward curved portion 8 Manual feed tray (manual feed unit)
9 Manual paper feed path 9a Downward curved part 10 Paper dust container (paper powder container)
A Image forming apparatus

Claims (3)

An image forming apparatus that feeds a sheet to an image recording unit through a main sheet conveyance path that rises in a substantially vertical direction from a sheet feeding unit, and sequentially records images on the fed sheet,
In the middle of the main sheet transport path, the merging portion where the sheet conveying path to another path merge upward through the downward curved portion is formed, and below the confluence portion is installed paper dust accommodating section,
A flexible film is attached to the guide wall of the main paper transport path at each end of the main paper transport path from the paper feed section and the junction with the main paper transport path of the other path. And
The film always closes the opening of each merging portion in the main paper conveyance path, and when the leading edge of the recording paper fed to the main paper conveyance path comes into contact, the film is deformed and opened by the contact pressure, An image forming apparatus configured to allow passage of recording paper . The image forming apparatus according to claim 1.
The paper transport path of the other path is a reverse paper transport path for reversing the paper that has passed through the image recording section and feeding it again to the image recording section and / or a manual paper transport path from the manual paper feed section. An image forming apparatus. The image forming apparatus according to claim 1, wherein
An image forming apparatus, wherein the image recording unit is a positively charged electrophotographic recording unit.

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