JP2006027168A - Image formation device, shutter mechanism and shutter members - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image formation device which requires no troublesome cleaning by making the scattered/dropped toner or powder dust or foreign substance hardly enter into an exposure unit from the opening of an exposure passage section and by making the scattered/dropped toner or powder dust or foreign substance deposited on a seal glass installed at the opening of the exposure passage section or on the permeation section formed at the exposure passage section for making the degradation of image quality such as an image with white streaks prevented. <P>SOLUTION: The image formation device is equipped with an opening/closing shutter 1 which can be freely opened and closed at the opening/closing angle θ of 90° or less against an opening slit 73Y as the exposure passage section through which a laser beam 69Y emitted from an optical scanner 53 passes and a driving means 4 which opens or closes the opening/closing shutter 1. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus, a shutter mechanism, and a shutter member. More specifically, the present invention relates to a copying machine, a printer, a facsimile machine, and a plotter including a digital copying machine provided with writing means for writing on a photoconductor as an image carrier by exposure. The present invention relates to an image forming apparatus such as a shutter mechanism and a shutter member.

In an image forming apparatus used as a copying machine including a digital copying machine, a laser printer, or the like, an optical scanning device that forms a latent image by scanning and exposing the surface of a photosensitive member that is an image bearing member is used as a photosensitive member and a developing device. A device disposed under (developer) is known (for example, see Patent Documents 1 and 2).
In an image forming apparatus having such a configuration, toner or dust that spills or scatters from a developing device or a developing unit is emitted from a laser light source of an optical scanning device or an optical writing unit (hereinafter referred to as “laser beam”). ) If it accumulates in the emission part or adheres to the optical components inside the optical scanning device or optical writing unit, the laser beam is blocked, resulting in image quality degradation such as a “white streak image” or “color unevenness image”. End up.

  Therefore, as a technique for preventing image quality deterioration such as a white streak image and a color unevenness image, a technique described in Japanese Patent Laid-Open No. 2000-263839 (Patent Document 3) has been proposed. In this technique, as shown in FIG. 1, an upward passage window (16) formed in an optical scanning device (14) through which a laser beam passes toward a photosensitive member (10), and a passage window (16 ), A moving means (driving mechanism including a stepping motor (48), etc.) for moving the shutter (42), and a moving range of the shutter (42) are positioned on the optical path of the laser beam. And an opening (54) as a laser beam passage portion that does not pass directly under the development point of the photoconductor (10).

FIG. 1 and FIG. 15 of JP 2000-305417 A FIG. 16 of JP-A-2003-334899 JP 2000-263839 A

  However, in the technique described in Japanese Patent Laid-Open No. 2000-263839 (Patent Document 3), since the shutter (42) having the opening (54) formed upward is moved in the left-right direction in the drawing, Even if the portion (54) does not pass through the development point of the photosensitive member, scattered / falling toner, dust, etc. enter the inside of the optical scanning device (14) from the opening (54). Image quality degradation will occur.

On the other hand, as described in paragraph “0030” of the same publication, even if the opening (54) is made a transmission part or covered with a sealing glass, the amount of generated toner such as scattered / falling toner or dust is reduced. Depending on the degree, scattering or falling toner, dust, or foreign matter may accumulate on the transmission part or on the seal glass, and in order to prevent the occurrence of white streak images etc. Appropriate cleaning is required. Such cleaning is troublesome and annoying for service personnel.
Then, although installation of the cleaning apparatus for performing cleaning automatically etc. can be considered, when it does so, a structure will become complicated and cost will become high.

  In addition, since the entire shutter (42) is moved in the left-right direction in the figure, even if the stroke of moving the shutter (42) is small, the design layout is restricted and the size of the apparatus is increased. May be invited.

  Therefore, the present invention has been made to eliminate the deterioration of image quality such as white streak images, and scattering / falling toner, dust, or foreign matters can be exposed from the opening (opening slit, etc.) of the exposure passage portion to the exposure apparatus (writing). Means) Difficult to enter inside, or scattering / falling toner, dust or foreign matter accumulates on the seal glass provided at the opening (opening slit, etc.) of the exposure passage part or the transmission part formed at the exposure passage part. The main object of the present invention is to provide an image forming apparatus, a shutter mechanism, and a shutter member that do not require troublesome cleaning.

The purpose of each claim is as follows.
The object of the present invention is to provide an opening / closing means that can be opened and closed at an opening angle of less than 90 degrees with respect to the exposure passage portion, and a drive means for opening and closing the opening / closing means. Toner, dust, foreign matter, etc. are less likely to enter the writing means from the opening (opening slit, etc.) of the exposure passage part, and scattered / falling toner, dust, foreign matter, etc. are on the seal glass, transmission part, etc. of the exposure passage part. It is an object of the present invention to provide an image forming apparatus that can maintain high image quality without deteriorating image quality such as a white streak image, which does not require troublesome cleaning by being deposited on the surface.

The object of the invention of claim 5 is that the opening / closing means is provided with an area in which the projection surface in the vertical direction of the opening / closing means with respect to the exposure passage portion covers the entire exposure passage portion when the opening / closing means is fully opened. It is an object of the present invention to more reliably achieve the object of the present invention as defined in claims 1 to 4 by providing the means with a role of a scissors.
The object of the invention of claim 6 is to further improve the sealing property of the opening / closing means with respect to the exposure passage portion by configuring the opening / closing means with respect to the exposure passage portion to be secured when the opening / closing means is closed. Accordingly, it is an object of the present invention to more reliably achieve the object of the present invention.

The object of the invention described in claim 7 is to achieve the object of the invention described in claim 6 by forming each peripheral part of the opening / closing means or the exposure passage part in an uneven shape.
The object of the invention described in claim 8 is to provide the elastic body in at least one of the opening / closing means and the peripheral portion of the exposure passage portion, thereby achieving the object of the invention of claim 6 and generating a closing sound of the opening / closing means. It is to ease.
An object of the invention of claim 9 is to form at least one of the opening / closing means and the peripheral part of the exposure passage part with resin, and to produce the elastic body by two-color molding with the resin, for example, by manually operating the elastic body. The object of the present invention is to achieve the object of the present invention by reducing the cost.

An object of the invention described in claim 10 is to achieve the object of the invention described in any one of claims 1 to 9 in a color image forming apparatus.
The object of the invention described in claim 11 is that, for example, a unitized photoconductor or developing means as an image carrier is formed by configuring the driving means with an operation member that is operated by an operation in conjunction with an opening / closing operation of the opening / closing means. When toner drops, such as during replacement, the fallen toner or the like is less likely to enter the writing means from the opening (opening slit, etc.) of the exposure passage portion, or the falling toner or the like is sealed on the seal glass or transmission portion of the exposure passage portion. It is an object of the present invention to provide an image forming apparatus that can maintain high image quality without deteriorating image quality such as a white streak image, which does not require troublesome cleaning by being deposited on the image.

  The object of the present invention is to limit the exposure state of the exposure passage portion as much as possible when exposure is necessary, for example, by controlling the driving means to open / close the opening / closing means at a predetermined timing. As a result, scattering / falling toner, dust or foreign matter is less likely to enter the writing means from the opening (opening slit, etc.) of the exposure passing portion, or scattering / falling toner, dust or foreign matter is sealed on the exposure passing portion. An object of the present invention is to provide an image forming apparatus that can maintain high image quality without deteriorating image quality such as a white streak image, which does not require troublesome cleaning by being deposited on glass or a transmission part.

  The object of the present invention is that in the color image forming apparatus, the driving means is controlled to open / close the opening / closing means at a predetermined timing, and the opening / closing means and the driving means are for black from the writing means. By providing one for exposure and at least one for exposure other than for black, the exposure state of the exposure passage portion is divided into a monochrome (monochrome monochrome) image formation and a color image formation. Can be limited as much as possible when exposure is necessary, so that scattering / falling toner, dust, or foreign matter can be prevented from entering the writing means from the opening (opening slit, etc.) of the exposure passage, or can be scattered / dropped. There is no need for troublesome cleaning by depositing toner, dust or foreign matter on the seal glass or transmission part of the exposure passage area, especially when forming color images. It is to provide an image forming apparatus capable of further eliminating image quality deterioration of the white streak image or the like to maintain a more higher image quality.

The object of the invention described in claim 15 is to achieve the object of the invention described in any one of claims 1 to 14 when the writing means is an optical scanning device that performs optical writing with a laser beam. is there.
The object of the invention described in claim 16 is to achieve the object of the invention described in any one of claims 1 to 14 when the writing means performs optical writing with light from the LED array.

The object of the invention of claim 17 is to open and close by configuring the opening and closing means so that when the opening and closing means is fully opened, the projection surface in the vertical direction of the opening and closing means with respect to the exposure passage portion covers the entire exposure passage portion. By giving the means the role of scissors, scattering / falling toner, dust or foreign matter can be prevented from entering the writing means from the opening (opening slit, etc.) of the exposure passage section, There is no need to perform troublesome cleaning by depositing dust or foreign matter on the seal glass or transmission part of the exposure passage portion, and maintaining high image quality without deterioration of image quality such as a white streak image.
The object of the invention of claim 18 is to ensure that when the opening / closing means is closed, the sealing of the opening / closing means with respect to the exposure passage portion is ensured, so that scattered / falling toner, dust, foreign matter, etc. are exposed to the exposure passage portion. It is difficult to intrude into the writing means from the opening (opening slit, etc.), or troublesome cleaning is performed by scattering or falling toner, dust, or foreign matter accumulating on the seal glass or transmission part of the exposure passage part. It is to maintain high image quality by eliminating image quality degradation such as white streak images that need not be performed.

An object of the invention described in claim 19 is to achieve the object of the invention described in claim 18 by forming each peripheral part of the opening / closing means or the exposure passage part in an uneven shape.
The object of the invention of claim 20 is to provide an elastic body in at least one of the opening / closing means and the peripheral portion of the exposure passage portion, thereby achieving the object of the invention of claim 18 and generating a closing sound of the opening / closing means. It is to ease.
The object of the invention of claim 21 is to form at least one of the opening / closing means and the peripheral portion of the exposure passage portion with resin, and to produce the elastic body by two-color molding with the resin, for example, by manually operating the elastic body. The object is to achieve the object of the invention of claim 20 and to reduce the cost.

In order to solve the above-described problems and achieve the above-described object, the invention according to each claim employs the following characteristic means and configuration.
According to the first aspect of the present invention, an image carrier, development means for developing a latent image disposed on the image carrier and opposed to the image carrier, and a lower part of the image carrier are provided. An image forming apparatus comprising: a writing unit that forms a latent image on the image carrier; and an exposure passage unit through which exposure from the writing unit passes, with an opening angle of less than 90 degrees with respect to the exposure passage unit. It has an opening / closing means that can be freely opened and closed, and a drive means that drives to open and close the opening / closing means.

According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the opening / closing means is disposed between the image carrier and the writing means.
According to a third aspect of the present invention, in the image forming apparatus according to the second aspect, the opening / closing unit partitions the at least one of the image carrier and the developing unit and the writing unit, the partition having the exposure passage unit. It is provided in the member.
According to a fourth aspect of the present invention, in the image forming apparatus according to the second aspect, the exposure passage unit is formed in the writing unit itself, and the opening / closing unit is disposed in the vicinity of the exposure passage unit. It is characterized by that.

  According to a fifth aspect of the present invention, in the image forming apparatus according to any one of the first to fourth aspects, when the opening / closing means is fully opened, a vertical projection surface of the opening / closing means with respect to the exposure passage portion is The opening / closing means has an area covering the entire exposure passage portion.

According to a sixth aspect of the present invention, in the image forming apparatus according to any one of the first to fifth aspects, when the opening / closing means is closed, the sealing of the opening / closing means with respect to the exposure passage portion is ensured. It is characterized by comprising.
According to a seventh aspect of the present invention, in the image forming apparatus according to the sixth aspect of the present invention, each of the peripheral portions of the opening / closing means or the exposure passage portion is formed in an uneven shape.
According to an eighth aspect of the present invention, in the image forming apparatus according to the sixth aspect, an elastic body is provided in at least one of the opening / closing means and the peripheral portion of the exposure passage portion.
According to a ninth aspect of the present invention, in the image forming apparatus according to the eighth aspect, at least one of the opening / closing means and the peripheral portion of the exposure passage portion is formed of resin, and the elastic body is two-color molded with the resin. It is characterized by having been produced.

According to a tenth aspect of the present invention, in the image forming apparatus according to any one of the first to ninth aspects, at least one of the image carrier, the developing unit, the writing unit, the opening / closing unit, and the driving unit is provided. , A plurality of them are arranged.
According to an eleventh aspect of the present invention, in the image forming apparatus according to any one of the first to tenth aspects, the driving unit includes an operation member that is operated by an operation in conjunction with an opening / closing operation of the opening / closing unit. It is characterized by that.
According to a twelfth aspect of the present invention, in the image forming apparatus according to any one of the first to tenth aspects, the driving unit is controlled to open / close the opening / closing unit at a predetermined timing. To do.

According to a thirteenth aspect of the present invention, in the image forming apparatus according to the tenth aspect, the driving unit is controlled to open / close the opening / closing unit at a predetermined timing, and the opening / closing unit and the driving unit are connected to the writing unit. 1 is arranged corresponding to the black exposure from the above, and at least one is arranged corresponding to the exposure other than the black exposure.
According to a fourteenth aspect of the present invention, in the image forming apparatus according to the thirteenth aspect, the driving unit is arranged corresponding to the black exposure when the image carrier is written only by the black exposure. Further, the opening / closing means disposed corresponding to the exposure other than for black is controlled to close so that the opening / closing means opens.

According to a fifteenth aspect of the present invention, in the image forming apparatus according to any one of the first to fourteenth aspects, the writing unit is an optical scanning device that performs optical writing with a laser beam.
According to a sixteenth aspect of the present invention, in the image forming apparatus according to any one of the first to fourteenth aspects, the writing unit performs optical writing with light from an LED array.

According to a seventeenth aspect of the present invention, in the shutter mechanism comprising the exposure passage portion, the opening / closing means and the driving means according to any one of the first to fourth aspects, the opening passage portion is fully opened when the opening / closing means is fully opened. The opening / closing means includes an area in which a vertical projection surface of the opening / closing means covers the entire exposure passage portion.
The invention according to claim 18 is the shutter mechanism comprising the exposure passage part, the opening / closing means and the driving means according to any one of claims 1 to 4 or claim 17, wherein when the opening / closing means is closed, The opening / closing means with respect to the exposure passage portion is configured to be sealed.

According to a nineteenth aspect of the present invention, there is provided a shutter mechanism comprising the exposure passage portion, the opening / closing means and the driving means according to any one of the first to fourth aspects, or the seventeenth or eighteenth aspect, wherein the opening / closing means or the exposure passage. Each peripheral part of the part is formed in an uneven shape.
According to a twentieth aspect of the invention, there is provided a shutter mechanism comprising the exposure passage section, the opening / closing means and the driving means according to any one of the first to fourth aspects and the claim 17, 18 or 19, wherein the opening / closing means and the opening / closing means. An elastic body is provided in at least one of the peripheral portions of the exposure passage portion.

  According to a twenty-first aspect of the present invention, the elastic body according to the twentieth aspect is formed by forming at least one of the opening / closing means and the peripheral portion of the exposure passage portion with a resin and two-color molding with the resin. This is a shutter member.

  According to the present invention, it is possible to provide a novel image forming apparatus, a shutter mechanism, and a shutter member by solving the above problems. The effects for each claim are as follows.

  According to the first to fourth aspects of the present invention, the apparatus includes the opening / closing means that can be opened and closed at an opening angle of less than 90 degrees with respect to the exposure passage portion, and the driving means that drives the opening / closing of the opening / closing means to be scattered and dropped. Toner, dust, foreign matter, etc. are less likely to enter the writing means from the opening (opening slit, etc.) of the exposure passage part, and scattered / falling toner, dust, foreign matter, etc. are on the seal glass, transmission part, etc. of the exposure passage part. Therefore, it is possible to provide an image forming apparatus that can maintain high image quality without deteriorating image quality such as a white streak image, which does not require troublesome cleaning.

According to the fifth aspect of the present invention, when the opening / closing means is fully opened, the opening / closing means is configured to have an area in which the projection surface in the vertical direction of the opening / closing means with respect to the exposure passage portion covers the entire exposure passage portion. The effect of the inventions of claims 1 to 4 can be obtained more reliably by giving the means the role of a cypress.
According to the sixth aspect of the present invention, when the opening / closing means is closed, the sealing of the opening / closing means with respect to the exposure passage portion is ensured, thereby further improving the sealing performance of the opening / closing means with respect to the exposure passage portion. Thus, the effects of the first to fourth aspects of the invention can be achieved more reliably.

According to the seventh aspect of the present invention, the peripheral portion of the opening / closing means or the exposure passage portion is formed in a concavo-convex shape, whereby the effect of the sixth aspect of the invention is achieved.
According to the eighth aspect of the present invention, the elastic member is provided in at least one of the opening / closing means and the peripheral portion of the exposure passage portion, so that the effect of the invention of the sixth aspect is achieved and the closing sound of the opening / closing means is reduced. You can also
According to the ninth aspect of the invention, at least one of the opening / closing means and the peripheral portion of the exposure passage portion is formed of resin, and the elastic body is made by two-color molding with the resin, for example, the elastic body by hand In addition to the effect of the eighth aspect of the invention, the cost can be reduced.

According to the tenth aspect of the present invention, the color image forming apparatus achieves the effects of the first aspect of the present invention.
According to the eleventh aspect of the present invention, the driving means is constituted by an operation member that is operated by an operation in conjunction with an opening / closing operation of the opening / closing means, so that, for example, a unitized photoconductor or developing means as an image carrier. When toner drops, such as during replacement, the fallen toner or the like is less likely to enter the writing means from the opening (opening slit, etc.) of the exposure passage portion, or the falling toner or the like is sealed on the seal glass or transmission portion of the exposure passage portion. Thus, it is possible to provide an image forming apparatus that can maintain high image quality without deteriorating image quality such as a white streak image, which does not require troublesome cleaning by being deposited on the image.

  According to the twelfth aspect of the present invention, the driving means is controlled to open / close the opening / closing means at a predetermined timing, so that the exposure state of the exposure passage portion can be limited as much as possible when exposure is necessary. As a result, scattering / falling toner, dust or foreign matter is less likely to enter the writing means from the opening (opening slit, etc.) of the exposure passing portion, or scattering / falling toner, dust or foreign matter is sealed on the exposure passing portion. It is possible to provide an image forming apparatus that can maintain high image quality without deteriorating image quality such as a white streak image, which does not require troublesome cleaning by being deposited on glass or a transmission portion.

  According to the invention described in claims 13 and 14, in the color image forming apparatus, the driving means is controlled to open / close the opening / closing means at a predetermined timing, and the opening / closing means and the driving means are for black from the writing means. By providing one for exposure and at least one for exposure other than for black, the exposure state of the exposure passage portion is divided into a monochrome (monochrome monochrome) image formation and a color image formation. Can be limited as much as possible when exposure is necessary, so that scattering / falling toner, dust, or foreign matter can be prevented from entering the writing means from the opening (opening slit, etc.) of the exposure passage, or can be scattered / dropped. There is no need for troublesome cleaning by depositing toner, dust or foreign matter on the seal glass or transmission part of the exposure passage area, especially when forming color images. It is possible to provide an image forming apparatus capable of further eliminating image quality deterioration of the white streak image or the like to maintain a more higher image quality.

According to the seventeenth aspect of the present invention, when the opening / closing means is fully opened, the opening / closing means is provided with an area in which the projection surface in the vertical direction of the opening / closing means with respect to the exposure passage portion covers the entire exposure passage portion. By giving the means the role of scissors, scattering / falling toner, dust or foreign matter can be prevented from entering the writing means from the opening (opening slit, etc.) of the exposure passage section, It is possible to maintain high image quality without deteriorating image quality such as a white streak image, which does not require troublesome cleaning by depositing dust or foreign matter on the seal glass or transmission portion of the exposure passage portion.
According to the eighteenth aspect of the present invention, when the opening / closing means is closed, the opening / closing means is sealed with respect to the exposure passage portion so that the toner can be scattered / dropped toner, dust or foreign matter. It is difficult to intrude into the writing means from the opening (opening slit, etc.), or troublesome cleaning is performed by scattering or falling toner, dust, or foreign matter accumulating on the seal glass or transmission part of the exposure passage part. Therefore, it is possible to maintain high image quality by eliminating image quality degradation such as white streak images that need not be performed.

According to the nineteenth aspect of the present invention, the peripheral portion of the opening / closing means or the exposure passage portion is formed in a concavo-convex shape, whereby the effect of the eighteenth aspect of the invention is achieved.
According to the twentieth aspect of the present invention, the elastic member is provided in at least one of the opening / closing means and the peripheral portion of the exposure passage portion, so that the effect of the invention of the eighteenth aspect is achieved and the closing sound of the opening / closing means is reduced. You can also
According to the invention of claim 21, at least one of the opening / closing means and the peripheral portion of the exposure passage portion is formed of resin, and the elastic body is produced by two-color molding with the resin, for example, by manual operation. In addition to the effect of the invention described in claim 20, the cost can be reduced.

  Embodiments including the best mode for carrying out the present invention will be described below with reference to the drawings. In each of the embodiments and modifications, components such as members and components having the same function and shape are denoted by the same reference numerals and will not be described after being described once. In order to simplify the drawings and the description, even components that are to be represented in the drawings may be omitted as appropriate without being specifically described in the drawings. In the case of quoting and explaining constituent elements such as published patent gazettes, the reference numerals including the background art described above are shown in parentheses to distinguish them from those of the embodiment and modification examples.

  First, a schematic overall configuration and operation of an image forming apparatus to which the present invention is applied will be described with reference to FIG. The image forming apparatus shown in the figure includes a photoconductor as an image carrier arranged for each of four colors of yellow (Y), magenta (M), cyan (C), and black (Bk), and each photosensor. A developing device as a developing means for developing a latent image formed on each photoconductor disposed opposite to the photoconductor, and writing for forming a latent image on each photoconductor arranged below each photoconductor and each developing device An optical scanning device as a means, and sequentially superimposing and transferring each color toner image onto an intermediate transfer belt 57 as an intermediate transfer member, and then transferring the four color full-color toner images onto a transfer paper P as a sheet-like recording medium. This is a tandem-type full-color image forming apparatus 40 (hereinafter simply referred to as “image forming apparatus 40”) that forms a full-color image by transferring all at once.

  In FIG. 7, reference numeral 41 denotes an apparatus main body that forms the framework of the image forming apparatus 40. In the apparatus main body 41, four photoconductors 51Y, 51M, 51C, 51Bk as image carriers are arranged in the horizontal direction in this order from left to right in the drawing. Around each of the photoconductors 51Y, 51M, 51C, and 51Bk, image forming units 56Y and 56M for forming four color images of yellow (Y), magenta (M), cyan (C), and black (Bk). , 56C, 56Bk are arranged. A full color image is formed by these image forming portions 56Y, 56M, 56C, and 56Bk. Since the image forming units 56Y, 56M, 56C, and 56Bk for each color perform the same configuration and operation, only the yellow (Y) image forming unit 56Y disposed in the leftmost portion will be described. Description of the other image forming units 56M, 56C, and 56Bk is omitted by attaching the same Arabic numerals to the same portions and adding alphabetical characters representing the colors.

  The image forming unit 56Y includes a drum-shaped photoreceptor 51Y (hereinafter referred to as “photoreceptor drum 51Y”), and a yellow (Y) image in the order of the rotation direction disposed around the photoreceptor drum 51Y and indicated by arrows in the drawing. A charging device (not shown) (see brush-like charging device 52Y shown in FIG. 1) as a charging means for uniformly charging the surface of the photosensitive drum 51Y for repeatedly forming the photosensitive drum 51Y and a charging surface of the photosensitive drum 51Y. A laser beam 69Y that is an exposure for yellow (Y) for optically writing an electrostatic latent image, a developing device 54Y as a developing unit that develops the electrostatic latent image on the photosensitive drum 51Y with yellow (Y) toner, and photosensitive A cleaning device (not shown) as a cleaning means for cleaning the body drum 51Y (refer to the cleaning device 55Y shown in FIG. 1) and the like. That.

  The image forming unit 56Y is configured to be detachable from the apparatus main body 41 and is unitized. The photoconductive drum 51Y is a well-known photoconductor that has photoconductivity and forms an electrostatic latent image on its surface, and is made of, for example, a well-known organic photoconductor. The photoconductive drum 51Y is rotatably supported by a unit side plate (not shown) constituting the image forming unit 56Y so as to rotate clockwise as indicated by an arrow in FIG. 7, and is driven to rotate by a drive motor as a driving unit (not shown). The photoconductive drum 51Y is arranged to be slightly separated downward from the Heisei and intermediate transfer belt 57.

  In FIG. 7, reference numeral 53 denotes a laser beam 69Y, a magenta (M) laser beam 69M, a cyan (C) laser beam 69C, and a black (Bk) laser beam 69Bk. , 51C, and 51Bk, an optical scanning device 53 as writing means for irradiating the charged surfaces, respectively. The optical scanning device 53 generates a laser beam in accordance with an image signal for each color and irradiates (exposes) the photosensitive drum 51Y with writing means for forming an electrostatic latent image on the charged surface of the photosensitive drum 51Y or exposure. It has functions and configurations as means. The optical scanning device 53 includes a laser diode (LD) (not shown) as a laser light source that generates a laser beam (laser light), a polygon mirror 70 that scans the laser beam emitted from the LD for each color, and various mirror groups. A known laser beam scanning optical system (not shown) is provided.

  In FIG. 7, reference numerals 70Y, 70M, 70C, and 70Bk denote laser beam emitting sections that emit laser beams 69Y, 69M, 69C, and 69Bk for the respective colors generated by the optical scanning device 53, and reference numeral 72 denotes an image forming section 56Y. , 56M, 56C, and 56Bk and a partition plate as a partition member that partitions the optical scanning device 53 are shown. In the partition plate 72, opening slits 73Y, 73M, 73C, and 73Bk are formed as exposure passing portions through which the laser beams 69Y, 69M, 69C, and 69Bk pass.

  Since each of the opening slits 73Y, 73M, 73C, and 73Bk is formed in the partition plate 72 in the same rectangular shape and with the same dimensions, the opening slit 73Y will be described below as a representative. The opening slit 73Y extends in the axial direction of the photosensitive drum 51Y corresponding to the near side and the far side of the paper surface of FIG. 7, and is formed in an elongated rectangular shape with a predetermined width in the left-right direction of FIG.

  As described above, in the image forming apparatus 40, the electrostatic latent image is generated by the laser beams 69Y, 69M, 69C, and 69Bk emitted from the optical scanning device 53 from below the four photosensitive drums 51Y, 51M, 51C, and 51Bk. Therefore, toner or the like may fall from the developing devices 54Y, 54M, 54C, and 54Bk, the photosensitive drums 51Y, 51M, 51C, and 51Bk during the optical writing. Well expected. Therefore, a partition plate 72 is required for separating the optical scanning device 53 and each process unit including the developing devices 54Y, 54M, 54C, 54Bk and the like.

In each of the opening slits 73Y, 73M, 73C, and 73Bk, there may be a case where a transmission part made of a transparent member that does not hinder the passage of the laser beams 69Y, 69M, 69C, and 69Bk, a seal glass, and the like are provided as appropriate. In addition, each of the laser beam emitting portions 70Y, 70M, 70C, and 70Bk is also covered with a transparent member that does not interfere with the emission and passage of the laser beams 69Y, 69M, 69C, and 69Bk, so that the inside of the optical scanning device 53 is completely completed. In some cases, it is hermetically sealed. With such a configuration, the problem described in the column of problems to be solved by the invention occurs.
Each of the developing devices 54Y, 54M, 54C, 54Bk and the optical scanning device 53 is unitized and has a device configuration that can also be called the developing units 54Y, 54M, 54C, 54Bk, and the optical writing unit 53. It is noted.

  An intermediate transfer belt 57 that is an endless belt is stretched close to and opposed to the upper side in FIG. 7 where the photosensitive drums 51Y, 51M, 51C, and 51Bk are arranged. The intermediate transfer belt 57 is stretched between the driving roller 58 and the driven roller 59 so as to rotate and travel in the direction of the arrow (counterclockwise) in the drawing. The intermediate transfer belt 57 is applied with an optimum tension by tension rollers 62a, 62b, 62c and the like arranged at the illustrated positions.

  In FIG. 7 facing each of the photoconductive drums 51Y, 51M, 51C, 51Bk, above the transfer pressure rollers 63Y, 63M as transfer devices to which a transfer bias voltage is applied with the intermediate transfer belt 57 interposed therebetween. 63C and 63Bk are provided. The transfer pressure rollers 63Y, 63M, 63C, and 63Bk are slightly separated from the Heisei and intermediate transfer belt 57, and are formed on the photosensitive drums 51Y, 51M, 51C, and 51Bk for each color to be described later. In the process of transferring the toner image to the intermediate transfer belt 57, the intermediate transfer belt 57 is displaced so as to come into contact with the photosensitive drums 51Y, 51M, 51C, 51Bk by contacting the intermediate transfer belt 57 and pressing it downward. It is configured freely.

A transfer roller 61 to which a bias voltage for transfer is applied is provided on the drive roller 58 via an intermediate transfer belt 57 so as to be able to contact and separate. The drive roller 58 and the transfer roller 61 constitute a color image transfer unit 60. A corona discharger or a transfer brush may be used instead of the transfer pressure rollers 63Y, 63M, 63C, 63Bk.
On the driven roller 59 side, a cleaning device (not shown) for removing toner remaining on the surface of the intermediate transfer belt 57 is provided so as to be able to contact and separate from the intermediate transfer belt 57.

  Each of the developing devices 54Y, 54M, 54C, and 54Bk uses a two-component developer, and only the color of the toner is different. The developing device 54Y contains yellow toner and carrier, the developing device 54M contains magenta toner and carrier, the developing device 54C contains cyan toner and carrier, and the developing device 54Bk contains black toner and carrier. The electrostatic latent images on the photosensitive drums 56Y, 51M, 51C, 51Bk formed by a known method using the optical scanning device 53 are developed by the respective developing rollers (see the developing roller 80Y shown in FIG. 1).

  Here, for convenience of explanation, the configuration of the developing device 54Y will be briefly described with reference to FIG. The developing roller 80Y employs a magnetic brush developing system that uses a developing means that rotates a non-magnetic sleeve around a fixed magnet. The developing device 54Y has a known configuration including a developer paddle 81Y that is a developer agitator, a conveying screw 82Y that is a toner replenisher, and the like.

  The conveying screw 82Y has a structure in which blades are spirally wound. The developer paddle 81Y has, for example, spiral blades and eight radial plates in order to provide a developer stirring function and a transport function. The developer paddle 81Y and the transport screw 82Y respectively transport the developer in the opposite axial directions by rotation, and distribute the developer evenly in the longitudinal direction of the developing roller 80Y. The configurations of the other developing devices 54M, 54C, and 54Bk are the same as described above.

The transfer sheet P is transferred at a predetermined timing by the registration roller pair 68 by selecting any one of the sheet feeding cassette 64 and the body sheet feeding device 65 disposed at the lower part of the apparatus body 41. Sent out.
The paper feeding cassette 64 and the main body paper feeding device 65 are mainly different in the size in which the transfer paper P is stacked and stored, and have almost the same configuration. Therefore, the paper feeding cassette 64 will be described as a representative. The paper feed cassette 64 is a cassette in which transfer paper P is stacked and stored, a paper feed roller 66 that is disposed above the cassette and feeds the uppermost transfer paper P one by one, and is fed by the paper feed roller 66. It is mainly composed of a pair of separation rollers 67 for separating and transporting the transferred transfer paper P one by one. A transfer material guide plate and a conveyance roller pair (not shown) are disposed in the transfer material conveyance path between the separation roller pair 67 and the registration roller pair 68 of the main body sheet feeding device 65.

  The image forming apparatus 40 employs a so-called front loading method in which a user is located on the front side of the paper surface shown in FIG. Therefore, by appropriately opening and closing a front cover (not shown) provided on the front side of the paper so as to be opened and closed and an inner cover (not shown) provided on the inner side of the front cover so as to be opened and closed, Attachment / detachment / replacement of the image forming portions 56Y, 56M, 56C, 56Bk, and attachment / detachment / replacement of the developing devices 54Y, 54M, 54C, 54Bk constituting a process cartridge that is detachable from the apparatus main body 41, for example. Alternatively, the transfer paper P is replenished by operating the paper feed cassette 64 and the main body paper feed device 65.

  In FIG. 7, which is the downstream side of the transfer material conveyance path, in the upper right part of the apparatus main body 41, a separation device (not shown) for separating the transfer paper P from the intermediate transfer belt 57 is driven via the intermediate transfer belt 57. 58 is provided opposite to 58. A fixing device 74 having a fixing roller 75 and a pressure roller 76 for fusing and fixing the toner images of the respective colors transferred onto the transfer paper P is disposed above the separating device. Further, a pair of paper discharge rollers 78 is disposed above the fixing device 74 via a paper discharge guide plate (not shown), and a transfer paper P on which a toner image is formed is placed to the left of the paper discharge roller pair 78. A paper discharge port 77 for discharging paper and a paper discharge unit 77 having a paper discharge tray are provided.

Next, the operation during full color image formation will be described.
When a full-color image formation signal is transmitted by a key operation or the like on an operation panel (not shown), yellow (Y), cyan (C), magenta (M), and black (Bk) image forming units 56Y, 56M, 56C, 56Bk operates at a predetermined timing, and toner images of the respective colors are formed on the photosensitive drums 51Y, 51M, 51C, and 51Bk. This is exemplified by the image forming unit 56Y. The photosensitive drum 51Y rotates in the clockwise direction in FIG. 1 and its outer surface is uniformly charged by a charging device (not shown), and then from the LD of the optical scanning device 53. Laser light is irradiated in accordance with the image signal, exposed and imaged on the photosensitive drum 51Y while being scanned by the polygon mirror 71, and an electrostatic latent image for yellow (Y) is formed. When the photosensitive drum 51Y on which the electrostatic latent image is formed faces the developing device 54Y, the developing roller 80Y (see FIG. 1) that is a developer carrying member in the developing device 54Y causes the developer in the developing device 54Y to be discharged. By being transported to the developing nip region facing the photosensitive drum 51Y, the toner in the developer is supplied and attached to the electrostatic latent image formed on the surface of the photosensitive drum 51Y and developed, and the photosensitive drum 51Y is developed. A yellow (Y) visualized toner image is formed thereon.
In the other color image forming units 56M, 56C, and 56Bk, toner images of the respective colors are formed in the same manner as the image forming unit 56Y.

  The intermediate transfer belt 57 is rotated counterclockwise by a driving motor (not shown) along with the start of an image forming cycle in which toner images of the respective colors are formed on the photosensitive drums 51Y, 51M, 51C, 51Bk, and for each transfer. Formed on the photosensitive drums 51Y, 51M, 51C, and 51Bk through the pressing operation of the intermediate transfer belt 57 to the photosensitive drums 51Y, 51M, 51C, and 51Bk by the pressure rollers 63Y, 63M, 63C, and 63Bk. The yellow (Y), cyan (C), magenta (M), and black (Bk) toner images are accurately aligned on the intermediate transfer belt 57 in this order to form a full-color toner image of four colors. The

  On the other hand, the transfer paper P selected to be fed by any one of the paper feed cassette 64 and the main body paper feed device 65 by a key operation on an operation panel (not shown) is taken out by the paper feed roller 66 and separated into a pair of separation rollers. 67 is separated one by one and sent to the registration roller pair 68 along the transfer material conveyance path, and then the full-color toner image in which the leading edge of the transfer paper P is formed on the intermediate transfer belt 57 by the registration roller pair 68. Are sent to the transfer area of the transfer section 60 in synchronization with each other. Then, when the full-color toner image formed on the intermediate transfer belt 57 passes through the transfer area of the transfer unit 60, it is transferred onto the transfer paper P by the action of an electric field.

  The transfer paper P on which the full-color toner image is formed is separated from the intermediate transfer belt 57 by a separation device (not shown) and then sent to the fixing device 74. The full-color toner image is melted and pressure-fixed by the fixing device 74. A full-color image is completed and discharged onto a paper discharge tray (not shown) via a paper discharge roller pair 78 of the paper discharge unit 77. Thereby, a full color copy is obtained.

On the other hand, residual toner, paper dust, etc. remaining on the surface of the photosensitive drum 51Y without being completely transferred to the transfer paper P are removed and collected by the cleaning device (not shown) provided with a cleaning blade or the like. Further, residual toner, paper dust and the like on the intermediate transfer belt 57 are also removed by the cleaning device (not shown). The surface of the photosensitive drum 51Y that has passed through the cleaning device is then uniformly charged by a charging device (not shown), and the next image forming process is repeated. Similar unique operations are performed in the remaining image forming units 56M, 56C, and 56Bk in the same manner.
The image forming apparatus 40 is an example of the image forming apparatus according to the present invention, and the image carrier is not limited to a drum-shaped photosensitive member, and may be an endless belt-shaped member or a writing unit, for example. The exposure from is not limited to the laser beam from the laser light source, but may be one that forms an electrostatic latent image with the light from the LED array.

(First embodiment)
With reference to FIGS. 1 and 2, the shutter mechanism according to the first embodiment and the image forming apparatus 20 including the shutter mechanism will be described.
Compared with the conventional image forming apparatus 40 shown in FIG. 7, the image forming apparatus 20 passes through the exposure beam through which the laser beam 69 </ b> Y emitted from the optical scanning device 53 passes as shown in FIG. 1. The main difference is that it has an opening / closing shutter 1 as an opening / closing means (opening / closing member) that can be opened and closed at an opening angle of less than 90 degrees with respect to the opening slit 73Y as a portion, and a drive means 4 that drives the opening / closing shutter 1 to open and close. To do.
The shutter mechanism includes an opening slit 73 </ b> Y, an opening / closing shutter 1 (or an opening / closing shutter 1 </ b> A described later), and a driving unit 4.

  The opening / closing shutter 1 has a base end portion fixed to the support shaft 2 and is provided with two bearing members formed on the partition plate 72 in the vicinity of both end edges of the opening slit 73Y on the near side and the back side of the paper surface of FIG. 3, the support shaft 2 is supported so as to be rotatable by a predetermined angle, so that it can be opened and closed between an open position indicated by a solid line in FIG. 1 and a closed position indicated by a two-dot chain line in FIG. . The opening / closing shutter 1 shown in FIG. 1 is configured such that the opening angle θ of the free end between the open position and the closed position (hereinafter referred to as “opening / closing angle θ”) is 60 degrees. The opening / closing shutter 1A shown in FIG. 2 is configured such that the opening / closing angle θ is 30 degrees. The opening / closing angle θ of the opening / closing shutters 1, 1 </ b> A can be easily set, for example, by providing a protrusion-like stopper that restricts the opening angle of the bearing member 3, or by restricting it on the driving means 2 side.

  The opening / closing shutters 1 and 1A may be made of any material as long as it is a member that can block scattered or falling toner, dust, or foreign matter from entering the optical scanning device 53 from the opening slit 73Y. However, if it is integrally formed of resin, sheet metal, etc., it can be manufactured relatively inexpensively. The open / close shutter 1 is large and shaped to cover the entire range of the opening slit 73Y when it is in the closed position, and extends in the axial direction of the photosensitive drum 51Y corresponding to the near side and the far side of the paper surface of FIG. It is formed in an elongated rectangular shape with a predetermined width in the left-right direction of the figure.

  The opening / closing angle θ of the opening / closing shutter 1 with respect to the opening slit 73Y is set to be less than 90 degrees when the opening / closing shutter 1 occupies the open position in FIG. 1 and FIG. This is because the opening / closing shutters 1 and 1A themselves have the role of a scissors (庇) as represented by a vertical line indicated by an alternate long and short dash line. When the opening / closing angle θ is 90 degrees or more, when the opening / closing shutters 1 and 1A occupy the open position, there is no use of the scissors to prevent the toner, dust, and the like descending due to its own weight from entering the opening slit 73Y. It will not be.

Referring to FIG. 3, two opening / closing shutters 1 having different sizes and dimensions when the opening area of opening slit 73 </ b> Y (the opening width in the left-right direction × the length in the X direction in FIG. 2B) is constant. Consider the opening / closing angle of 1A and the projected length / area.
3 (a) and 3 (b), the symbol B indicates that the opening / closing shutters 1A and 1 have the above-described opening / closing shutters 1A and 1 when the opening / closing shutters 1A and 1 are fully opened by occupying the open positions at different opening angles θ = 30 degrees and 60 degrees. The length required for the opening and closing shutters 1A and 1 to have the role of a hiss, that is, the projection length of the opening and closing shutter 1A and 1 in the vertical direction (also in the vertical direction) with respect to the opening slit 73Y. The same width dimension in the left-right direction in the figure is represented. Symbol L1A represents the same shutter length when the open / close shutter 1A is fully opened, and symbol L1 represents the same shutter length when the open / close shutter 1 is fully opened.

  As shown in FIG. 3A, when the opening / closing shutter 1A occupies the open position at the opening / closing angle θ = 30 degrees and is fully opened, the opening / closing shutter 1A itself has a role of a scissors. It can be easily understood that the opening / closing shutter 1A has to have an area where the vertical projection plane (also the vertical direction) of the opening / closing shutter 1A covers the entire opening slit 73Y.

  Similarly, as shown in FIG. 3B, when the opening / closing shutter 1 occupies the open position at the opening / closing angle θ = 60 degrees and is fully opened, the opening / closing shutter 1 itself has a function of a long shadow. It can be easily understood that the opening / closing shutter 1A has to have an area in which the projection plane in the vertical direction (also the vertical direction) of the opening / closing shutter 1A with respect to the slit 73Y covers the entire opening slit 73Y.

  From the concept of the projection length and projection plane shown in FIGS. 3A and 3B, the opening / closing shutter 1 with the opening / closing angle θ = 60 degrees is larger than the opening / closing shutter 1A with the opening / closing angle θ = 30 degrees. It turns out that it becomes. Therefore, by setting the opening / closing angle θ of the opening / closing shutter to the minimum necessary, for example, by setting the opening / closing shutter angle to less than 60 °, which is smaller than 90 °, the opening / closing shutter can be reduced in size and saved. It is preferable that the shutter has a projection length B and an area that covers the entire opening slit 73Y of the laser beam 69Y so as to cover the opening slit 73Y so that toner and dust do not enter the optical scanning device 53 (writing unit).

  The opening / closing shutter 1 (or 1A) is not shown in FIG. 1, but with respect to the opening slits 73M, 73C, and 73Bk as exposure passage portions through which the other laser beams 69M, 69C, and 69Bk pass. Opening and closing at an opening angle θ of 60 degrees (30 degrees for the opening and closing shutter 1A) is arranged on the partition plate 72 in the vicinity of each opening slit 73M, 73C, 73Bk.

With reference to FIGS. 2A and 2B, the driving means 4 of the open / close shutter 1A (or 1) will be described. In FIG. 2A, the spring 7 and the face plate 10 are omitted, and in FIG. 2B, the support shaft 2 and the bearing member 3 are omitted.
As shown in FIGS. 2A and 2B, the driving unit 4 includes an arm 9 fixed to the opening / closing shutter 1A near one end of the support shaft 2 and an X direction parallel to the axis of the photosensitive drum 51Y. A slide lever 5 having a cam portion 5b that is movably supported and can come into contact with the arm 9, a spring (compression spring) 7 as an urging means for always urging the slide lever 5 upward in the drawing, and an opening / closing shutter 1A Can be pressed against the torsion coil spring (not shown) interposed between the base end portion of the opening / closing shutter 1A and the bearing member 3 that always urges the shutter in the closed position, and one end portion of the slide lever 5. It is mainly comprised from the face plate 10 shown with a dashed-two dotted line in the same figure as an operation member act | operated by.

The arm 9 is fixed to the support shaft 2 so as to hang down with respect to the base end portion of the opening / closing shutter 1A. In FIG. 2A, the open / close shutter 1A indicated by the solid line represents the closed position, and the open / close shutter 1A indicated by the two-dot chain line represents the open position.
The slide lever 5 is formed with a long hole 5a extending in the X direction. The slide lever 5 is movable in the X direction by being screwed to the lower wall (back wall) of the partition member 72 with the two stepped screws 6 loosely inserted into the long hole 5a. ing. The cam portion 5 b is formed on an inclined surface that is inclined with an acute angle with respect to the X direction of the slide lever 5.

The spring 7 is mounted between the other end of the slide lever 5 and the spring receiving member 8 fixed to the lower wall of the partition member 72, and always biases the slide lever 5 upward in the figure. When no external force is applied to the slide lever 5, the open / close shutter 1A occupies the closed position by the biasing force of the torsion coil spring.
The face plate 10 will be described with reference to, for example, the front loading type image forming apparatus 40 shown in FIG. 7, and a front cover provided on the front side of the paper so as to be opened and closed, or a member fixed to the inner wall surface of the inner cover. It is.

Next, the operation of the driving unit 4 will be described.
2A and 2B, at the time of an image forming operation in which the front cover and the inner cover are closed against the urging force of the spring 7 and the torsion coil spring, one end of the slide lever 5 is When pressed by the face plate 10 in the X direction, the slide lever 5 slides downward in the X direction as shown by a two-dot chain line, and the cam portion 5b makes the arm 9 orthogonal to the X direction. By pushing and moving in this direction, the opening / closing shutter 1A opens about the support shaft 2 as shown by a two-dot chain line in FIG. As a result, the laser beam 69Y from the optical scanning device 53 can pass through the opening slit 73Y and irradiate the photosensitive drum 51Y (not shown in FIG. 2, see FIG. 1), that is, optical writing is possible.

  On the other hand, when the image forming unit 56Y is attached or detached when the photosensitive drum 51Y is exchanged, or when the process cartridge type developing device 54Y is exchanged or attached, the front cover or the inner cover is opened. The face plate 10 is further moved upward from the position indicated by the two-dot chain line in FIG. 2B to the upper side in the view in the X direction, so that the slide lever 5 is moved from the position indicated by the two-dot chain line by the biasing force of the spring 7 to the solid line. As shown by, slide upward in the X direction. At this time, the urging force of the torsion coil spring causes the open / close shutter 1A to occupy the closed position with the support shaft 2 as the center, as shown by a solid line in FIG. 2A and a broken line in FIG. 2B.

  The configuration of the driving means of the opening / closing shutter 1 is basically the same as that of the driving means 4 of the opening / closing shutter 1A, and the sliding amount of the slide lever 5 is only slightly increased as the opening / closing angle is different. For this reason, in FIGS. 2A and 2B, parentheses are shown to indicate that the driving means of the opening / closing shutter 1 is substantially the same as the driving means 4 of the opening / closing shutter 1A.

  In the example shown in FIG. 2, the size of the opening slit 73Y is set to be small so that the opening slit 73Y at the closed position of the opening / closing shutter 1A (or 1) is shielded with sufficient margin. In order to make the pushing force when the face plate 10 is closed as small as possible and to be efficient by reducing the component force by the cam 5b to the arm 9 when the opening / closing shutter 1A (or 1) is opened / closed / swung, an opening is required. The opening range of the slit 73Y is partially expanded to a position just below the support shaft 2 (within the swing range of the arm 9) so that the arm 9 hangs vertically from the fixing portion of the open / close shutter 1A (or 1) with the support shaft 2. You may make it provide in.

  The components excluding the face plate 10 of the driving means 4 correspond to the opening / closing shutters 1A (or 1) respectively disposed in the other three opening slits 73M, 73C, 73Bk, respectively, as represented by FIG. Arranged in the same manner as shown. The face plate 10 is provided to extend in the left-right direction in FIG. 2B so as to correspond to the opening / closing shutters 1A (or 1) disposed in the four opening slits 73Y, 73M, 73C, 73Bk.

  Accordingly, when the image forming sections 56Y, 56M, 56C, and 56Bk are replaced when the photosensitive drums 51Y, 51M, 51C, and 51Bk are replaced, and the process cartridge type developing devices 54Y, 54M, 54C, and 54Bk are replaced. Even if toner drops or dust or foreign matter falls during replacement / removal, each opening slit 73Y, 73M, 73C, 73Bk is shielded by the opening / closing shutter 1A (or 1), so that toner, dust, foreign matter, etc. are opened. The slits 73Y, 73M, 73C, and 73Bk do not enter the optical scanning device 53.

(Second Embodiment)
FIG. 4 shows the driving means 24 according to the second embodiment.
Compared with the driving unit 4 shown in FIG. 2, the driving unit 24 is a predetermined unit instead of a method of operating and interlocking the opening / closing operation of the opening / closing shutter 1A (or 1) by an external human operation force, for example. The main difference is that a system controlled to open and close at the timing is adopted. Hereinafter, the drive unit 24 will be described on behalf of the opening / closing shutter 1A.
The shutter mechanism of the second embodiment includes an opening slit 73Y, an opening / closing shutter 1A (or 1), and a driving unit 24.

  As shown in FIG. 4, the driving means 24 includes an arm 29 that is fixed perpendicularly to the support shaft 2 to which the base end of the opening / closing shutter 1A is fixed and has a long hole 29a, and a partition plate 72 in the vicinity of the arm 29. A pull-type solenoid 25 having a plunger 26 fixed to the arm 29 and connected to the arm 29 via a connecting pin 27, and the arm 29 and the plunger 26 are wound around the opening / closing shutter 1A so as to always occupy the closed position. The main component is a spring 28 (compression spring).

  The arm 29 and the plunger 26 are connected to each other by the connection pin 27 being loosely inserted into the long hole 29 a of the arm 29. The solenoid 25 is electrically connected to the CPU of a microcomputer as a control means, which includes a CPU (Central Processing Unit), a RAM (Read / Write Storage Device), a ROM (Read Only Storage Device), a timer, etc., not shown. Connected to each other and controlled by the CPU. The ROM stores in advance a program for operating the image forming apparatus 20 and related data for performing the control function of the CPU.

  The driving means 24 is disposed in the same manner as shown in FIG. 2 corresponding to the opening / closing shutters 1A respectively disposed in the other three opening slits 73M, 73C, 73Bk. That is, the opening / closing shutter 1A and the driving unit 24 correspond to one black (Bk: black) laser beam 69Bk from the optical scanning device 53, and one corresponding to a laser beam other than black (Bk: black). At least one (three laser beams 69Y, 69M, and 69C in this embodiment) is provided.

Next, the operation of the driving unit 24 will be described.
At the time of image forming operation, the solenoid 25 is turned on / excited against the urging force of the spring 28 in response to a command from the CPU, so that the plunger 26 is drawn. As shown by the two-dot chain line in FIG. As a result, the laser beam 69Y from the optical scanning device 53 can pass through the opening slit 73Y and irradiate the photosensitive drum 51Y (not shown in FIG. 4, see FIG. 1), that is, optical writing is possible.

  On the other hand, when the image forming portion 56Y is attached or detached when the photosensitive drum 51Y is exchanged, or when the process cartridge type developing device 54Y is exchanged or attached, the solenoid 25 remains off in accordance with a command from the CPU. As a result, the urging force of the spring 28 causes the opening / closing shutter 1A to close and occupy the closed position as shown by the solid line in FIG.

  The overall operation of the image forming apparatus 20 is as follows. For example, at the time of monochrome / monochromatic image forming operation, that is, when optical writing is performed on the photosensitive drum 51Bk in the image forming unit 56Bk only by the black (Bk: black) laser beam 69Bk, according to a command from the CPU, The driving means 24 arranged corresponding to the black (Bk: black) laser beam 69Bk so that the open / close shutter 1A arranged corresponding to the black (Bk: black) laser beam 69Bk is opened. Each of the laser beams 69Y, 69M, so that the open / close shutter 1A disposed corresponding to each of the laser beams 69Y, 69M, 69C disposed corresponding to other than the black (Bk: black) laser beam 69Bk is closed. The drive means 24 arranged corresponding to 69C is controlled respectively.

  Therefore, according to the second embodiment, in the full-color image forming apparatus 20, the driving unit 24 is controlled to open and close the opening / closing shutter 1A at a predetermined timing, and the opening / closing shutters 1A and 24 driving unit are connected to the optical scanning device. 53 corresponding to the laser beam 69Bk for black (Bk: black) from 53 and at least one corresponding to each laser beam 69Y, 69M, 69C other than for black (Bk: black), The exposure of the black (Bk: black) opening slit 73Bk and the black (Bk: black) opening slits 73Y, 73M, 73C is performed separately for monochrome (monochrome monochrome) image formation and color image formation. It becomes possible to limit the state as much as possible when exposure is necessary. As a result, scattered / falling toner, dust, foreign matter, etc. are less likely to enter the optical scanning device 53 from the respective opening slits 73Y, 73M, 73C, and scattered / falling toner, dust, foreign matter, etc., enter each of the opening slits 73Y, 73M. No need for cumbersome cleaning by depositing on the seal glass or transmission part provided as appropriate in 73C, and even higher image quality with no further deterioration of image quality such as white streak images during color image formation. Can be maintained.

(Modification 1)
A shutter mechanism and an image forming apparatus according to Modification 1 of the first embodiment will be described with reference to FIG.
In the first modification, when the opening / closing shutter 1A (or 1) of the first embodiment is closed, the sealing property of the opening / closing shutter 1A (or 1) with respect to each of the opening slits 73Y, 73M, 73C, and 73Bk is ensured. In place of the opening / closing shutter 1A (or 1), specifically, the opening / closing shutter 31 having a concavo-convex portion formed on the periphery thereof, and the opening slits 73Y, 73M, 73C, 73Bk The main difference is that the partition plate 72 has each of the opening slits 30aY (30aM, 30aC, 30aBk) formed with concave and convex portions. Hereinafter, the opening / closing shutter 31 and the opening slit 30aY will be described as a representative.

  The opening slit 30aY is different from the opening slit 73Y only in that a convex rising wall 30a is formed at an edge around the opening of the partition plate 72. When the open / close shutter 31 is in the closed position as compared with the open / close shutter 1A, a concave portion 31a loosely fitted into the rising wall 30a and a convex portion 31b loosely fitted into the opening slit 30aY are formed. Only the difference.

  When the opening / closing shutter 31 swings clockwise about the support shaft 2 and occupies the closed position as shown by a two-dot chain line, the recess 31a of the opening / closing shutter 31 is loosely fitted to the rising wall 30a and is opened and closed. Since the convex portion 31b of the shutter 31 is loosely fitted into the opening slit 30aY, the sealing performance is improved, and toner, dust, etc. enter the optical scanning device 53, or the laser beam emitting portion 70Y (FIG. (Not shown, see FIG. 1) to prevent deposition. Similar operations are performed in the other opening slits 30aM, 30aC, and 30aBk (not shown), and similar advantages can be obtained.

  In the first modification, not only the opening / closing shutter 31 but also an opening / closing shutter (not shown) having an opening / closing angle similar to the above-described uneven shape, in other words, an opening / closing angle similar to the above-described uneven shape having an opening / closing angle of less than 90 degrees. The open / close shutter can be configured in the same manner as described above to obtain the same advantages. Of course, not only the driving means 4 but also the driving means 24 can be adopted and operated in the same manner as in the second embodiment.

(Modification 2)
With reference to FIG. 6, a shutter mechanism and an image forming apparatus according to Modification 2 of the first embodiment will be described.
Modification 2 is different from the opening / closing shutter 1A (or 1) of the first embodiment in that an elastic body 33 is provided on the lower surface (back side) of the opening / closing shutter 1A (or 1). Hereinafter, the opening / closing shutter 1A will be described as a representative.

  The elastic body 33 is made of an appropriate elastic body such as sponge or foam rubber, and is attached and fixed to the lower surface of the opening / closing shutter 1A with, for example, a double-sided tape or an adhesive. The elastic body 33 has the opening slit 73Y sealed by the elastic body 33 when the opening / closing shutter 1A swings clockwise about the support shaft 2 and occupies the closed position as shown by a two-dot chain line. Thus, the airtightness is improved, and toner, dust, etc. are prevented from entering the inside of the optical scanning device 53 or falling and depositing on the laser beam emitting portion 70Y (not shown in FIG. 5, see FIG. 1). is doing. At the same time, there is also a function to mute the closing sound of the opening / closing shutter 1A.

  The elastic body 33 is not limited to the rectangular shape shown in FIG. 6, and the member may be saved by forming a shape in which the central portion is hollowed out corresponding to the entire periphery of the opening edge of the opening slit 73 </ b> Y. Further, instead of attaching the elastic body 33 to the lower surface of the opening / closing shutter 1A, the elastic body 33 is attached to the entire periphery of the opening edge of the opening slit 73Y, or the lower surface of the opening / closing shutter 1A and the opening of the opening slit 73Y. The elastic body 33 may be attached to the entire periphery of the edge.

  In Modification 2, not only the opening / closing shutter 1A but also the opening / closing shutter 1 having an opening / closing angle of 60 degrees, in other words, an opening / closing shutter having an opening / closing angle of less than 90 degrees can be configured in the same manner as described above to obtain the same advantages. it can. Of course, the second modification is not limited to the driving unit 4, and the driving unit 24 may be employed and operated as in the second embodiment.

(Modification 3)
A shutter member, a shutter mechanism, and an image forming apparatus according to Modification 3 of Modification 2 will be described with reference to FIG.
In the third modification, as compared with the second modification, the opening / closing shutter 1A (or 1) is replaced with a structure in which the elastic body 33 is attached and fixed to the lower surface of the opening / closing shutter 1A (or 1) with double-sided tape or adhesive. Is made of resin (for example, ABS resin or polycarbonate resin (PC)), and an elastic body as a shutter member is formed on the lower surface of the resin opening / closing shutter 1A (or 1) by two-color molding with the resin. Is different.

In the third modification, instead of the structure in which the elastic body 33 in the second modification is affixed and fixed with a double-sided tape or an adhesive, a resin two-color molding method is used. The pasting process can be reduced, and the cost can be reduced.
Instead of forming the opening / closing shutter 1A (or 1) with resin, the partition plate 72 is formed with the resin, and the opening edge portion of the opening slit 73Y is made of an elastic body with the resin partition plate 72. You may produce by color molding.

  The opening / closing means includes opening / closing shutters 1, 1 </ b> A disposed in the partition member 72 near the opening slit to open / close the opening slits 73 </ b> Y, 73 </ b> M, 73 </ b> C, 73 </ b> Bk formed in the partition member 72 of FIGS. 1 and 2. In order to open and close the opening slits 30aY, 30aM, 30aC, and 30aBk formed in the partition member 72 of FIG. The laser beam emitting portions 70Y, 70M, 70C, and 70Bk as exposure passing portions formed in the optical scanning device 53 itself may be arranged to open and close.

  The shutter mechanism, shutter member, and image forming apparatus according to the present invention have four image forming portions 56Y, 56M, 56C, and 56Bk, that is, full color in which four photosensitive drums 51Y, 51M, 51C, and 51Bk are arranged in a tandem manner. The image forming apparatus 20 is not limited to the example of the image forming apparatus 40, and two image forming stations each capable of forming two-color images are arranged along the intermediate transfer member, for example, Japanese Patent Laid-Open No. 2000-305417. The present invention can also be applied to the image forming apparatus shown in FIGS. 1 and 15 of the publication and FIG. 16 of JP-A-2003-334989. In addition, the opening (54) is not limited to the image forming apparatus having the single photoconductor (10) and the optical scanning device 14 as shown in FIG. 1 of JP-A-2000-263839. Needless to say, the present invention can be applied in place of the shutter (42) having the above.

The writing means is not limited to the optical scanning device 53 but may be a well-known LED head or the like that performs optical writing with light from the LED array, and has the same advantages and effects as described above.
As described above, the present invention has been described with respect to specific embodiments and modifications. However, the technical scope disclosed by the present invention is limited to those exemplified in the above-described embodiments and modifications. However, those skilled in the art can configure various embodiments, modifications, and examples in accordance with the necessity and application within the scope of the present invention. If so, it is clear.

1 is a partial cross-sectional front view of a main part of an image forming apparatus including a shutter mechanism according to a first embodiment. (A) is an enlarged sectional view of Sb-Sb of the opening / closing shutter driving means shown in (b), and (b) is a reduced bottom view of (a) seen from the V direction. It is sectional drawing explaining the opening-and-closing angle of two opening-and-closing shutters from which a magnitude | size and a dimension differ, and projection length and area. FIG. 5 is an enlarged cross-sectional view around another driving means of the open / close shutter of FIG. 1. FIG. 10 is a cross-sectional view around a shutter mechanism according to a first modification. FIG. 10 is a cross-sectional view around a shutter mechanism of a second modification. 1 is a schematic front view of a full-color image forming apparatus to which the present invention is applied.

Explanation of symbols

1, 1A, 31 Open / close shutter (open / close means)
4, 24 Driving means 10 Face plate (operation member)
20 Image forming apparatus 25 Solenoid 33 Elastic bodies 51Y, 51M, 51C, 51Bk Photosensitive drum (image carrier)
53 Optical scanning device (writing means)
54Y, 54M, 54C, 54Bk Developing device (developing means)
72 Partition plate (partition member)
30aY, 30aM, 30aC, 30aBk, 73Y, 73M, 73C, 73Bk Opening slit (exposure passage part)
P transfer paper (example of sheet-like recording medium)

Claims (21)

An image carrier, a developing unit disposed opposite to the image carrier and developing a latent image formed on the image carrier, and a latent image disposed on the image carrier below the image carrier. In an image forming apparatus comprising: a writing unit that forms a light source; and an exposure passage unit through which exposure from the writing unit passes.
An image forming apparatus comprising: an opening / closing means that can be opened / closed at an opening angle of less than 90 degrees with respect to the exposure passage section; and a driving means that drives the opening / closing means to open / close. The image forming apparatus according to claim 1.
The image forming apparatus, wherein the opening / closing means is disposed between the image carrier and the writing means. The image forming apparatus according to claim 2.
The image forming apparatus, wherein the opening / closing means is provided on a partition member provided with the exposure passage section that partitions at least one of the image carrier and the developing means and the writing means. The image forming apparatus according to claim 2.
The exposure passage portion is formed in the writing means itself,
The image forming apparatus, wherein the opening / closing means is disposed in the vicinity of the exposure passage portion. The image forming apparatus according to any one of claims 1 to 4,
2. An image forming apparatus according to claim 1, wherein when the opening / closing means is fully opened, the opening / closing means has an area in which a vertical projection surface of the opening / closing means with respect to the exposure passage portion covers the exposure passage portion. The image forming apparatus according to claim 1,
An image forming apparatus configured to ensure sealing of the opening / closing means with respect to the exposure passage portion when the opening / closing means is closed. The image forming apparatus according to claim 6.
An image forming apparatus, wherein each opening and closing portion or each peripheral portion of the exposure passage portion is formed in a concavo-convex shape. The image forming apparatus according to claim 6.
An image forming apparatus comprising an elastic body in at least one of the opening / closing means and the peripheral portion of the exposure passage portion. The image forming apparatus according to claim 8.
An image forming apparatus, wherein at least one of the opening / closing means and the peripheral portion of the exposure passage portion is formed of a resin, and the elastic body is formed by two-color molding with the resin. The image forming apparatus according to any one of claims 1 to 9,
An image forming apparatus comprising a plurality of at least one of the image carrier, the developing unit, the writing unit, the opening / closing unit, and the driving unit. The image forming apparatus according to claim 1,
The image forming apparatus according to claim 1, wherein the driving unit includes an operation member that is operated by an operation in conjunction with an opening / closing operation of the opening / closing unit. The image forming apparatus according to claim 1,
The image forming apparatus, wherein the driving unit is controlled to open / close the opening / closing unit at a predetermined timing. The image forming apparatus according to claim 10.
The driving means is controlled to open / close the opening / closing means at a predetermined timing,
An image forming apparatus comprising: one opening / closing unit and one driving unit corresponding to black exposure from the writing unit and at least one corresponding to exposure other than black. The image forming apparatus according to claim 13.
The drive means supports exposure other than for black so that when the image carrier is written only by exposure for black, the opening / closing means arranged corresponding to the exposure for black opens. The image forming apparatus is controlled so that the opening / closing means arranged in a closed state is closed. The image forming apparatus according to any one of claims 1 to 14,
The image forming apparatus according to claim 1, wherein the writing means is an optical scanning device that performs optical writing with a laser beam. The image forming apparatus according to any one of claims 1 to 14,
The image forming apparatus, wherein the writing unit performs optical writing with light from an LED array. In the shutter mechanism comprising the exposure passage portion, the opening / closing means and the driving means according to any one of claims 1 to 4,
A shutter mechanism, wherein the opening / closing means includes an area where a projection surface in a vertical direction of the opening / closing means with respect to the exposure passage portion covers the exposure passage portion when the opening / closing means is fully opened. A shutter mechanism comprising any one of claims 1 to 4, or the exposure passage section according to claim 17, an opening / closing means and a driving means.
A shutter mechanism configured to ensure sealing of the opening / closing means with respect to the exposure passage when the opening / closing means is closed. A shutter mechanism comprising the exposure passage section according to any one of claims 1 to 4 and claim 17 or 18, an opening / closing means, and a driving means.
A shutter mechanism characterized in that each peripheral portion of the opening / closing means or the exposure passage portion is formed in an uneven shape. A shutter mechanism comprising the exposure passage portion, the opening / closing means, and the driving means according to any one of claims 1 to 4, or 17, 17, or 19.
A shutter mechanism comprising an elastic body in at least one of the opening / closing means and the peripheral portion of the exposure passage portion.   21. The shutter member according to claim 20, wherein at least one of the opening / closing means and the peripheral portion of the exposure passage portion is formed of a resin and is formed by two-color molding with the resin.

Images