JP2006184307A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus in which a trouble such as mixing of color or paper soiling due to toner not transferred to paper does not occurs even when an image data region exceeds the paper size. <P>SOLUTION: The image forming apparatus forms a latent image by scanning a photoreceptor surface with an optical beam, transfers a toner image formed by developing the latent image by toner to the paper and fixes the transferred image to form an image, and the image forming apparatus is provided with a manual feed tray transporting the paper into the image forming apparatus. The image forming apparatus is further provided with a paper width detecting means for detecting the width of the paper which is transported from the manual insertion tray and a scanning width restriction means restricting the width of the paper along a main scanning direction in the scanning region in which the photoreceptor is scanned with the optical beam so that the width of the paper along the main scanning direction does not exceed the width of the paper detected by the paper width detecting means. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus that does not cause troubles such as color mixing and paper contamination even when printing is performed with image data larger than the paper size.

  In an electrophotographic image forming apparatus such as a printer or a copying machine, an intermediate transfer such as an intermediate transfer belt or an intermediate transfer drum is achieved by increasing the transfer efficiency of transferring a toner image formed on the surface of a photosensitive drum onto a recording sheet. A so-called cleanerless image forming apparatus has been proposed in which a cleaner for cleaning the surface of a member or a photosensitive drum is omitted.

As such a cleanerless image forming apparatus, for example,
a. A developing device that also serves as a cleaner for removing transfer residual toner remaining on the photosensitive drum (Patent Document 1), and b. In an image forming apparatus having an intermediate transfer drum, the deformation rate when spherical toner that has not been transferred and remains on the photosensitive drum passes between the photosensitive drum and the contact charger is set in the range of 50 to 100%. Thus, the transfer efficiency from the photosensitive drum to the intermediate transfer drum is improved, and the cleaning means for cleaning the surface of the photosensitive drum is eliminated (Patent Document 2)
and so on.
JP-A-8-146696 JP 2003-162085 A

  In these image forming apparatuses, when the recording paper is set in the cassette, the paper width and the paper length are detected by the detecting means, and when the image data is larger than the size of the recording paper, an error display is performed to display the error. The image forming apparatus itself can be forcibly stopped.

  The image forming apparatus is provided with a manual feed tray for inserting a non-standard size paper. When printing on a thick paper such as a non-standard size paper or a postcard, the paper can be inserted from the manual feed tray for printing. It is common.

  However, since there is usually no paper size detection means in the manual feed tray, if the operator prints image data having a size larger than that of the paper by mistake, the toner in the area protruding from the paper is 100 because there is no paper to be transferred. % Downstream. Therefore, when the image is in color, the toner reaches the downstream developing device, so that a large amount of toners of different colors are mixed in the downstream developing device, resulting in color mixing. If the image is a single color, there will be no problem of color mixing, but if a larger size paper is fed after printing on the fixed-size paper or postcard, the toner stains the toner adhering to both side edges of the paper. Problem arises.

  The present invention has been made to solve the above problem. When printing is performed by inserting paper from a manual feed tray, the image data is not transferred to the paper even when the area of the image data exceeds the paper size. An object of the present invention is to provide an image forming apparatus in which troubles such as toner color mixing and paper contamination do not occur.

  According to the first aspect of the present invention, a latent image is formed by scanning the surface of the photosensitive member with a light beam, and the toner image formed by developing the latent image with toner is transferred to a sheet and fixed to form an image. And an image forming apparatus having a manual feed tray for feeding the paper into the image forming apparatus, a paper width detecting means for detecting the width of the paper fed from the manual feed tray, and the light beam Scanning width limiting means for limiting the width along the main scanning direction of the scanning area for scanning the photosensitive member so as not to exceed the width of the paper detected by the paper width detecting means. The present invention relates to an image forming apparatus.

  In the image forming member, when a sheet such as an irregular sheet such as a cardboard or a postcard is inserted into the manual feed tray, the width of the sheet is detected by a sheet width detecting unit. The scanning width by which the light beam scans the photosensitive member is limited by the scanning width limiting unit so as not to exceed the width of the sheet detected by the sheet width detecting unit. Even if the width of the sheet is exceeded, the area outside the width of the sheet on the surface of the photoreceptor is not exposed.

  Therefore, since no toner adheres to the area, troubles such as color mixing due to the toner that has not been transferred to the paper and paper contamination do not occur.

According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the scanning width limiting means is disposed on both sides of the optical path of the light beam and limits the scanning width by blocking the light beam. A pair of scanning width limiting members, wherein the distance between the scanning width limiting members is W1, the distance from the photoconductor to the scanning width limiting member is L1, and the paper width detected by the paper width detecting means is Assuming that PS is a scanning angle, which is an angle formed between the light beam and the photosensitive member surface at the end of the scanning region, θ, the interval W1 of the scanning width limiting member is:
W1 ≦ PS-2 × L1 × tan θ
The present invention relates to an image forming apparatus that is set so that

  Even in a cleanerless image forming apparatus, the surface of a photoconductor is usually scanned by deflecting a light beam by a deflecting means such as a polygon mirror or a swing mirror. However, in the image forming apparatus, the scanning width is limited. By blocking the light beam by the member, the width along the main scanning direction of the scanning region on the surface of the photosensitive member is regulated. Since the interval W1 of the scanning width limiting member is set according to the above formula, the width of the scanning region on the photosensitive member in the main scanning direction does not exceed the paper width PS.

According to a third aspect of the present invention, in the image forming apparatus according to the first aspect, the scanning width limiting unit is disposed on one side of the optical path of the light beam and limits the scanning width by blocking the light beam. One scanning width limiting member, wherein the distance from the center of the optical path of the light beam to the scanning width limiting member is W2, and the distance from the photoconductor to the scanning width limiting member is L2.
W2 ≦ PS / 2−L2 × tan θ
The present invention relates to an image forming apparatus in which the position of the scanning width limiting member is set so that the above relationship is established.

  As the manual feed tray provided in the image forming apparatus of the present invention, a sheet feed tray (a side register image recording apparatus) having only one sheet guide can be used in addition to a pair of sheet guides described later.

  In the image forming apparatus provided with the manual feed tray of the latter mode, a scanning width limiting unit is disposed on one side of the optical path of the light beam, and the scanning limiting member is interlocked with the paper guide so that the scanning width on the photoconductor. Can be regulated.

  In the image forming apparatus according to claim 3, the distance W <b> 2 from the center of the optical path of the light beam to the scanning width limiting member is set as described above, so that the main scanning direction of the scanning region on the photosensitive member is aligned. It is possible to prevent the width from exceeding the paper width PS.

  According to a fourth aspect of the present invention, in the image forming apparatus according to any one of the first to third aspects, the paper width detecting means guides the paper in the manual feed tray and adjusts the width of the paper. The image forming apparatus is a sheet guide that is movable in the width direction of the sheet, and the scanning width limiting member moves in the scanning direction of the light beam in conjunction with the sheet guide.

  In the image forming apparatus, the paper guide provided on the manual feed tray and the scanning width limiting member are interlocked to set a scanning area on the photosensitive member, in other words, a light shielding area that is not scanned with a light beam is set.

  Therefore, if the width of the paper guide is correctly aligned with the width of the paper so that the paper is not inserted at an angle, even if the image data area exceeds the width of the paper, it will be outside the width of the paper on the photoreceptor surface. Since this area is not exposed, troubles such as color mixing due to toner that has not been transferred to the paper and paper contamination are reliably prevented.

  According to a fifth aspect of the present invention, a latent image is formed by scanning the surface of the photosensitive member with a light beam emitted from an optical scanning device, and the toner image formed by developing the latent image with toner is transferred onto a sheet. An image forming apparatus having a manual feed tray for fixing and forming an image and feeding the paper into the image forming apparatus, wherein the shutter is positioned on an optical path of the light beam, and the shutter is opened and closed. The image forming apparatus includes a shutter opening / closing means and a paper detection means for detecting the paper inserted in the manual feed tray, and the shutter opening / closing means opens the shutter for a time during which the paper detection means detects the paper. Relates to the device.

  In the image forming apparatus, the shutter is opened and the photosensitive member is exposed only while the sheet passes through the sheet detecting means. Therefore, the image data of the area exceeding the sheet length is erroneously input and a print instruction is issued. However, only the length corresponding to the sheet length is exposed on the surface of the photoreceptor. Therefore, troubles such as color mixing and paper contamination due to toner that has not been transferred to the paper are reliably prevented.

  According to the sixth aspect of the present invention, a latent image is formed by scanning the surface of the photosensitive member with a light beam emitted from an optical scanning device, and the toner image formed by developing the latent image with toner is transferred onto a sheet. An image forming apparatus having a manual feed tray for fixing and forming an image and feeding the paper into the image forming apparatus, wherein the shutter is positioned on an optical path of the light beam, and the shutter is opened and closed. A shutter opening / closing means; and a paper detection means for detecting the paper inserted in the manual feed tray, wherein the shutter opening / closing means stores a time required for the paper to pass through the paper detection means, The image forming apparatus is characterized in that the shutter is opened so that the exposure time on the photoconductor does not exceed the stored time.

  In the image forming apparatus, even if the paper detection unit and the optical scanning device are separated, the photosensitive member is exposed by the optical scanning device only by a length corresponding to the paper length. Accordingly, even when image data in an area exceeding the paper length is erroneously input and a printing instruction is given, troubles such as color mixing due to toner that has not been transferred to the paper and paper contamination are reliably prevented.

  According to a seventh aspect of the present invention, there is provided the image forming apparatus according to the fifth or sixth aspect, wherein the width of the paper fed from the manual feed tray is detected, and the light beam is applied to the photosensitive member. The present invention relates to an image forming apparatus including a scanning width limiting unit that limits a width along a main scanning direction of a scanning region to be scanned so as not to exceed a width of a sheet detected by the sheet width detecting unit.

  In the image forming apparatus, only the area corresponding to the width and length of the sheet of the photoconductor is exposed, and toner does not adhere to other areas. Therefore, even when image data having an area exceeding the paper width as well as the paper length is input and printing is instructed, troubles such as color mixing due to toner that has not been transferred to the paper and paper contamination do not occur.

According to an eighth aspect of the present invention, in the image forming apparatus according to the first aspect, the scanning width regulating means is disposed on both sides of the optical path of the light beam, and the scanning width is limited by blocking the light beam. A pair of scanning width limiting members is provided, and the distance from the center of the optical path of the light beam to the scanning width limiting member is W2 and W2 ′, respectively, and the distance from the photoconductor to the scanning width limiting member is L2 and L2. ´
W2 ≦ PS / 2−L2 × tan θ
W2 ′ ≦ PS / 2−L2 ′ × tan θ
The position of the scanning width limiting member is set so that the above relationship is established.

  In the image forming apparatus, even when the installation position of the scanning width limiting member is different on the left and right, the intervals W2 and W2 ′ of the scanning width limiting member are set according to the above formula. Does not exceed the paper width PS.

  As described above, according to the present invention, when printing is performed by inserting paper from the manual feed tray, even if the image data area exceeds the paper size, color mixture due to toner that has not been transferred to the paper or paper Provided is an image forming apparatus in which troubles such as contamination do not occur.

1. Embodiment 1
A printer as an example of the image forming apparatus of the present invention will be described below.

  As shown in FIGS. 1A and 1B, the printer 100 according to the first embodiment forms a manual feed tray 2 into which the paper S is manually inserted and a toner image, which is inserted from the manual feed tray 2. The image forming transfer unit 4 to be transferred onto the sheet S, the optical scanning device 8 that emits a light beam to scan and expose the photosensitive drum 6 of the image forming transfer unit 4, and the light beam emitted from the optical scanning device 8 And a pair of scanning width limiting members 10 for blocking and limiting the scanning width on the photosensitive drum 6. 1A shows a configuration of the printer 100 viewed from the side, and FIG. 1B shows a configuration of the manual feed tray 2 viewed from the rear. The photosensitive drum 6 corresponds to a photoreceptor provided in the image forming apparatus of the present invention.

  The manual feed tray 2 includes a pair of paper guides 12 that can move in the paper width direction, in other words, in the main scanning direction of the photosensitive drum 6.

  As shown in FIGS. 1 and 2, the scanning width limiting member 10 includes a light-shielding plate 10A that blocks the light beam emitted from the optical scanning device 8, and an upper end of the light-shielding plate 10A in a direction perpendicular to the light-shielding plate 10A. A first link portion 10B that is continuous and is pivotally attached to a main frame (not shown) of the printer 100 by a rotating shaft 11 that extends vertically, and the lower end of the light-shielding plate 10A is opposite to the first link portion 10B. In the direction perpendicular to the light-shielding plate 10A, and a second link portion that is pivotally attached to the paper guide 12 by a rotating shaft 13 that extends in the vertical direction.

  As shown in FIG. 2A, when the paper guide 12 is positioned on the outside, the scanning width limiting members 10 are parallel to each other, but when the paper guide 12 moves inward, the scanning width limiting member 10 is As shown in FIG. 5B, the rotation is made inward about the rotation shaft 11, and the interval W1 of the scanning width limiting member 10, specifically, the interval of the light shielding plate 10A is reduced.

  The scanning width limiting member 10 may be connected to the paper guide 12 by a link mechanism 14 as shown in FIG. 3 instead of being directly connected to the paper guide 12 as shown in FIG.

  As shown in FIG. 3, the link mechanism 14 is pivotally attached to the main frame of the printer 100 by a rotary shaft 15A at the center, and is connected to the paper guide 12 by a connecting member 14C at one end. 14A and a second arm-like member 14B which is connected to the other end of the first arm-like member at one end by a connecting member 14D and which is pivotally attached to the main frame of the printer 100 at the central portion by a rotation shaft 15B. It is configured. The scanning width limiting member 10 is axially attached to the other end side of the second arm-shaped member 14 </ b> B and is guided along the main scanning direction of the optical scanning device 8.

  The connecting member 14C is pivotally attached to the paper guide 12 at one end and to the first arm-like member 14A at the other end. The connecting member 14D is pivotally attached to the first arm-like member 14A at one end and to the second arm-like member 14B at the other end.

  As shown by an arrow a in FIG. 3B, when the paper guide 12 moves inward, the first arm-like member 14A rotates around the rotation shaft 15A, and one end of the first arm-like member 14A is connected. While being pulled by the member 14C and moving inward, the other end side is moved outward. As a result, the one end side of the second arm-shaped member is pulled outward via the connecting member 14D, so the second arm-shaped member 14B rotates around the rotation shaft 15B and the second arm-shaped member 14B The other end side moves inward. Here, since the scanning width limiting member 10 is pivotally attached to the other end side of the second arm-shaped member 14B as described above, the scanning width limiting member 10 is also inward as shown by the arrow b in FIG. Moving.

Here, in both the mode shown in FIG. 2 and the mode shown in FIG. 3, the relationship between the interval between the paper guides 12 and the interval between the scan width limiting members 10 is as shown in FIG. The interval is W1, the distance from the photosensitive drum 6 to the scanning width limiting member 10 is L1, the paper width passing through the paper guide 12 is PS, and the photosensitive drum 6 is scanned by the light beam emitted from the optical scanning device 8. Assuming that a scanning angle, which is an angle formed by the light beam at the end of the scanning region that is the region to be formed, and the surface of the photosensitive drum 6 is θ, the W1
W1 ≦ PS−2 × L1 × tan θ (1)
The first link portion 10B and the second link portion 10C or the link mechanism 14 in the scanning width limiting member 10 are formed as given by the following equation. The sheet width PS is substantially equal to the interval between the sheet guides 12.

  As a result, as shown in FIG. 5, the light beam outside the paper width is shielded on the photosensitive drum 6.

  The manual feed tray 2 may have a mode in which the paper guide 12 is provided only on one side. In the above mode, the scanning width limiting member 10 may be provided only on one side of the optical path of the light beam R.

In the aspect in which the scanning width limiting member 10 is provided only on one side of the optical path of the light beam R, the distance from the center of the optical path of the light beam R to the scanning width limiting member 10 is W2, as shown in FIG. If the distance from 6 to the scanning width limiting member 10 is L2,
W2 ≦ PS / 2−L2 × tan θ (2)
The positional relationship between the paper guide 12 and the scanning width limiting member 10 may be set so that the above relationship is established.

  Hereinafter, the operation of the printer 100 will be described.

  When the sheet S is inserted into the manual feed tray 2 and the interval between the sheet guides 12 is adjusted to the sheet width PS, the scanning width limiting member 10 also moves in conjunction with the sheet guide 12, and the interval W1 given by the above equation (1). Set to

  The sheet S inserted in the manual feed tray 2 is conveyed toward the image forming transfer unit 4 along the conveying path P by the conveying roller 16, and is emitted from the optical scanning device 8 in the image forming transfer unit 4. The photosensitive drum 6 is scanned and exposed by the light beam R to form a latent image, and the latent image is developed with toner to form a toner image. Here, since the light beam R emitted from the optical scanning device 8 is shielded by the scanning width limiting member 10 at both ends of the scanning region, as shown in the knitted region in FIG. Both side edges of the paper S are shielded from light and are not exposed.

  Accordingly, since no toner adheres to the area, even if the sheet S passes through the image forming transfer unit 4 and the toner image is transferred, the toner does not adhere to both side edges of the sheet S.

  The sheet S that has passed through the image forming transfer unit 4 passes through the fixing unit 18 to fix the toner image.

  The sheet S on which the toner image is fixed is stacked on the stacking unit 20 located at the top of the printer 100.

  In the printer 100, even if image data having an area wider than the paper width PS is input, the outside of the area corresponding to the paper S in the photosensitive drum 6 is shielded by the scanning width limiting member 10 and exposed. Therefore, toner does not adhere.

  Therefore, troubles such as the paper S being soiled by the toner that has not been transferred to the paper S, or the toner adhering to both side edges of the paper when the paper having a width wider than the paper S is fed in may occur. There is no.

  In addition, since the paper guide 12 and the scanning width limiting member 10 are mechanically connected, the operation is reliable and repair is easy even if a failure occurs.

  Although the example in which the paper guide 12 and the scanning width limiting member 10 are mechanically connected has been described, the paper guide 12 and the scanning width limiting member 10 may be electrically linked. Further, instead of detecting the width of the paper S by the paper guide 12, the width of the paper S may be detected by an optical sensor or the like.

2. Embodiment 2
A printer as an example of the image forming apparatus of the present invention will be described below.

  As shown in FIG. 6A, the printer 102 according to the first embodiment forms a manual feed tray 22 into which the paper S is manually inserted and a toner image, and forms the toner image on the paper S inserted from the manual feed tray 22. On the optical path of the light beam R emitted from the image forming transfer unit 4 to be transferred, the optical scanning device 8 that scans and exposes the photosensitive drum 6 that the image forming transfer unit 4 has by emitting a light beam. The provided shutter 24 that can be opened and closed, the pair of transport rollers 16 that transport the paper S inserted from the manual feed tray 22 toward the image forming transfer unit 4 along the transport path R, and the image forming transfer unit 4. And a fixing unit 18 for fixing the toner image transferred to the paper S. The photosensitive drum 6 corresponds to a photoreceptor provided in the image forming apparatus of the present invention.

  A paper detection lever 26 that detects the leading edge of the paper S is provided between the transport roller 16 and the image forming transfer unit 4.

  The position where the toner image is transferred onto the sheet S from the length from the sheet detection lever 26 to the image forming transfer unit 4 in the conveyance path P and the position exposed by the light beam R from the optical scanning device 8 on the surface of the photosensitive drum 6. The paper detection lever 26 is disposed so that the length of the paper detection lever 26 becomes equal.

  As shown in FIG. 6B, the paper detection lever 26 has one end on the conveyance path P and is pivotally attached to the main frame (not shown) of the printer 102 with a shaft 25 at the center. . The other end is pivotally attached to the shutter 24. In the vicinity of the other end of the paper detection lever 26, a registration sensor 28 that detects that the paper S has passed through the paper detection lever 26 is disposed. The paper detection lever 26 is urged clockwise by the spring 27 in FIG.

  As shown in FIG. 7, the shutter 24 includes a fixed plate 24A fixed to the optical scanning device 8, and a movable plate 24B provided so as to overlap the fixed plate 24A and movable in the vertical direction in FIG. The fixed plate 24A and the movable plate 24B each have a slit 24C and a slit 24D provided along the horizontal direction. As shown in FIGS. 6B and 6C, the movable plate 24B is pivotally attached to the other end of the paper detection lever 26, and moves up and down in conjunction with the up and down movement of the other end.

  When the sheet S is not in contact with one end of the sheet detection lever 26 as shown in FIG. 6B, the movable plate 24B is raised as shown in FIG. The slit 24C of 24A is closed. Accordingly, since the shutter 24 is in a closed state, the light beam R emitted from the optical scanning device 8 is shielded by the movable plate 24B and the fixed plate 24A.

  On the other hand, as shown in FIG. 6C, when the paper S comes into contact with one end of the paper detection lever 26, the paper detection lever 26 rotates counterclockwise. As shown in FIG. 7 (B), the movable plate 24B is pulled down, and the slit 24C and the slit 24D overlap each other. Therefore, the light beam R emitted from the optical scanning device 8 passes through the slits 24C and 24D and reaches the photosensitive drum 6, and the photosensitive drum 6 is scanned and exposed by the light beam R that has passed.

  Hereinafter, the operation of the printer 102 will be described.

  When the paper S is inserted into the manual feed tray 22, the paper S is sent to the transport path P by the feed roller 23 provided on the outlet side of the manual feed tray 22.

  The paper S sent to the transport path P is transported toward the image forming transfer unit 4 by the transport roller 16, but the paper detection lever 26 is rotated clockwise by the spring 27 until the paper S comes into contact with one end. Therefore, the movable plate 24B of the shutter 24 is also raised, and the shutter 24 is in a closed state. Therefore, since the light beam R emitted from the optical scanning device 8 is shielded by the shutter 24, the photosensitive drum 6 is not exposed and no latent image is formed.

  When the paper S is transported along the transport path P and the leading edge contacts the paper detection lever 26, the paper detection lever 26 counterclockwise against the biasing force of the spring 27 as shown in FIG. Therefore, the movable plate 24B is pushed downward, and the shutter 24 is opened. Accordingly, the light beam R emitted from the optical scanning device 8 passes through the shutter 24 to scan and expose the surface of the photosensitive drum 6.

  While the paper S is passing through the paper detection lever 26, the paper detection lever 26 is held in the state shown in FIG. 6C, so the shutter 24 is also held open, and the light beam R is The surface of the photosensitive drum 6 is exposed through the shutter 24.

  When the paper S passes through the paper detection lever 26, the paper detection lever 26 returns to its original position as shown in FIG. The light beam R from the scanning device 8 is again shielded by the shutter 24.

  Therefore, in the printer 102, as shown by the knitted area in FIG. 8, the corresponding areas of the leading edge and the trailing edge of the sheet S on the surface of the photosensitive drum & are shielded from light and are not exposed.

  Accordingly, since no toner adheres to the region, even when the paper S passes through the image forming transfer unit 4 and the toner image is transferred, the toner does not adhere to the leading edge and the trailing edge of the paper S.

  The toner image that has passed through the fixing unit 18 is fixed on the sheet S that has passed through the image forming transfer unit 4.

  The sheet S on which the toner image is fixed is stacked on the stacking unit 20 located at the top of the printer 102.

  In the printer 102, even if image data having an area longer than the length of the paper S is input, the outside of the photosensitive drum 6 corresponding to the length of the paper S is shielded by the shutter 24 and is not exposed. Therefore, toner does not adhere.

  Therefore, troubles such as sheet contamination due to toner that has not been transferred to the sheet S do not occur.

  In addition, since the movable plate 24B of the shutter 24 and the paper detection lever 26 are mechanically connected, the operation is reliable and repair is easy even if a failure occurs.

  Although an example in which the shutter 24 and the paper detection lever 26 are mechanically connected has been described, the shutter 24 and the paper detection lever 26 may be electrically interlocked.

  Further, instead of detecting the paper S by the paper detection lever 26, the paper is detected by the registration sensor 28, the time is stored, and the time for opening the shutter 24 is determined based on the time to determine the photosensitive drum 6. May be exposed.

3. Embodiment 3
A full color printer which is another example of the image forming apparatus according to the present invention will be described below.

  As shown in FIG. 9, the full-color printer 104 according to the third embodiment forms a manual tray 32 into which the paper S is manually inserted and a toner image, and transfers the toner image onto the paper S inserted from the manual tray 32. The formation transfer unit 34, the optical scanning device 40 that emits a light beam to scan and expose the photosensitive drum 36Y, the photosensitive drum 36M, the photosensitive drum 36C, and the photosensitive drum 36K included in the image formation transfer unit 34, the optical scanning device 40, and the image A pair of scanning width limiting members 50 and a shutter 60 are provided between the formation transfer unit 34. The photosensitive drums 36Y to 36K correspond to photosensitive members included in the image forming apparatus of the present invention.

  The manual feed tray 32 is provided with a pair of paper guides 33 that can move along the width direction of the paper S.

The scanning width limiting member 50 is provided on both sides of the light beam emitted from the optical scanning device 40 and is connected to the paper guide 33 and the link mechanism 52. The interval W3 of the scanning width limiting member 50, the distance L3 from the photosensitive drums 36Y to 36K to the scanning width limiting member 50, the width PS of the paper passing through the paper guide 33, and the light emitted from the optical scanning device 40 Between the scanning angle θ at the end along the main scanning direction of the optical path of the beam,
W3 ≦ PS-2 × L3 × tan θ (3)
The scanning width limiting member 50 is linked to the paper guide 33 by the link mechanism 52 so that the above is established. The configuration of the scanning width limiting member 50 is as described in the first embodiment.

  Further, a feed roller 31A for feeding the paper S inserted from the paper tray 32 to the full-color printer 104, and a retard roller 31B for scooping the paper S so as to be fed one by one are provided immediately inside the manual feed tray 32. A registration sensor 64 for detecting the passage of the sheet S is provided immediately below the sheet S feeding path and adjacent to the retard roller 31B.

  The shutter 60 is opened and closed by shutter opening and closing means 62 such as a solenoid provided above the shutter 60. The detailed configuration of the shutter 60 is the same as that of the shutter 24 in the second embodiment.

  In the full-color printer 104, when the registration sensor 64 detects the tip of the paper S, the time from the detection of the leading edge of the paper S to the detection of the trailing edge is stored, and based on the time, the photosensitive drums 36Y to 36Y. The time for opening the shutter 60 is determined so that the exposure length on the photosensitive drum 36K does not exceed the length along the transport direction of the paper S, and the shutter opening / closing means 62 is only for the determined time. The shutter 60 is opened.

  In the image forming transfer unit 34, toner images of Y (yellow), M (magenta), C (cyan), and K (black) are formed on the photosensitive drum 36Y, the photosensitive drum 36M, the photosensitive drum 36C, and the photosensitive drum 36K, respectively. This is a photosensitive drum. A latent image formed by exposure with a light beam is provided downstream of the exposure position of the photosensitive drum 36Y, the photosensitive drum 36M, the photosensitive drum 36C, and the photosensitive drum 36K. A developing device 35Y, a developing device 35M, a developing device 35C, and a developing device 35K are provided for developing with the respective K color toners.

  The image forming transfer unit 34 further performs primary transfer of a primary transfer drum 37A to which toner images formed on the photosensitive drums 36Y and 36M are primarily transferred, and toner images formed on the photosensitive drums 36C and 36K. There are provided a primary transfer drum 37B, and a primary transfer drum 37A and a secondary transfer drum 38 to which the toner image transferred to the primary transfer drum 37B is transferred. Further, a final transfer roller 39 is provided so as to face the secondary transfer drum 38 with the conveyance path P1 of the paper S interposed therebetween.

  The optical scanning device 40 is an optical scanning device that scans and exposes the photosensitive drum 36Y, the photosensitive drum 36M, the photosensitive drum 36C, and the photosensitive drum 36K with the light beam RY, the light beam RM, the light beam RC, and the light beam RK, respectively. A laser light source 40A that generates four laser beams of a beam RY, a light beam RM, a light beam RC, and a light beam RK, and a light beam RY, a light beam RM, a light beam RC, and a light beam RK generated by the laser light source 40A A polygon mirror 40B that scans in the main scanning direction, and a light beam RY, a light beam RM, a light beam RC, and a light beam RK scanned by the polygon mirror 40B, respectively, are a photosensitive drum 36Y, a photosensitive drum 36M, a photosensitive drum 36C, and a photosensitive drum. At the same time, it is connected to the photosensitive drum 36Y, the photosensitive drum 36M, the photosensitive drum 36C, and the photosensitive drum 36K. Make and a f-theta optical system 40C.

  The full-color printer 104 includes a fixing unit 70 that fixes the toner image transferred onto the paper S by the secondary transfer drum 38 and a stacking unit 90 that stacks the paper S on which the toner image is fixed by the fixing unit 70.

  Further, a paper tray 80 for storing standard paper s of A3 size or A4 size is provided at the bottom of the full color printer 104.

  The full-color printer 104 further includes a pair of conveying rollers 92 that are a pair of rollers that convey the sheet S inserted from the manual feed tray 32 to the fixing unit 70 via the secondary transfer drum 38 along the path P1. , An exit side roller pair 94 that conveys the paper S on which the toner image is fixed by the fixing unit 70 toward the stacking unit 90, a feed roller pair 97 that feeds the standard paper s from the paper tray 80 to the full color printer 104, and a feed A conveyance roller pair 98 that conveys the standard sheet s fed by the roller pair 97 along the conveyance path P3 is provided. Here, the transport path P3 is a transport path that joins the transport path P1 and transports the standard paper s toward the secondary transfer drum 38 and the fixing unit 70.

  The outlet side roller pair 94 is formed so as to be able to reversely rotate. When double-sided printing is performed on the sheet S or the standard sheet s, the sheet S or the standard sheet s on which the toner image is fixed by the fixing unit 70 is returned by the reverse roller pair 94 and conveyed by the conveying roller pair 96. If the sheet is fed downward along the path P2, and the front and back surfaces of the sheet are reversed by the conveying roller pair 92 and then fed back into the conveying path P1, the toner image is transferred to the back surface.

  Hereinafter, the operation of the full-color printer 104 according to the third embodiment will be described.

  When the sheet S is inserted into the manual feed tray 32 and at the same time the interval between the sheet guides 33 is adjusted to the sheet width PS, the scanning width limiting member 50 also moves in conjunction with the sheet guide 33, and the interval W3 given by the above equation (3). Set to

  The sheet S inserted into the manual feed tray 32 is conveyed toward the image forming transfer unit 34 along the conveyance path P1 by the conveyance roller pair 92. At the same time, in the image forming transfer unit 34, the photosensitive drum 36Y, the photosensitive drum 36M, the photosensitive drum 36C, and the photosensitive drum 36K are formed by the light beam RY, the light beam RM, the light beam RC, and the light beam RK emitted from the optical scanning device 40. Each is scanned and exposed to form a latent image, and the latent image is developed with toner to form a toner image. Here, the light beam RY, the light beam RM, the light beam RC, and the light beam RK emitted from the optical scanning device 40 are shielded by the scanning width limiting member 50 at both ends of the scanning region.

  Further, when the paper S sent from the manual feed tray 32 passes below the registration sensor 64, the registration sensor 64 detects the presence of the paper S. A central control computer (not shown) of the full-color printer 104 stores the time from when the registration sensor 64 detects the leading edge of the paper S until the trailing edge is detected, and based on this time, the photosensitive drum 36Y. The time for opening the shutter 60 is determined so that the exposure length on the photosensitive drum 36K does not exceed the length along the conveyance direction of the paper S, and the shutter opening / closing means 62 is only for the determined time. Then, the shutter 60 is opened.

  Accordingly, as shown in FIG. 10 and the region knitted in FIG. 11, the region corresponding to the both side edges of the sheet S on the surface of the photosensitive drums 36Y to 36K is the scanning width limiting member 50, and the front end portion of the sheet S and The area corresponding to the rear end is shielded by the shutter 60, and only the portion corresponding to the central portion of the paper S is exposed. A portion corresponding to the central portion of the sheet S is developed by the developing device 35Y, the developing device 35M, the developing device 35C, and the developing device 35K, and a toner image is formed.

  The toner image formed on the photosensitive drum 36Y and the photosensitive drum 36M is transferred and superimposed on the primary transfer drum 37A, and the toner image formed on the photosensitive drum 36C and the photosensitive drum 36K is superimposed on the primary transfer drum 37B. It is transcribed and superimposed. Then, the toner images on the primary transfer drum 37A and the primary transfer drum 37B are superimposed on the secondary transfer drum 38 to form a full-color toner image. The full-color toner image formed on the secondary transfer drum 38 is transferred to the sheet S by the sheet S conveyed along the conveyance path P1 being nipped between the secondary transfer drum 38 and the final transfer roller 39. Is done.

  The sheet S on which the full-color image has been transferred is sent to the fixing unit 70 where the toner image is fixed, and is accumulated by the accumulating unit 90.

  As described above, in the full-color printer 104, the light beam RY to the light beam RK are shielded by the scanning width limiting member 50 and the shutter 60, and the photosensitive drum 36Y to the photosensitive drum 36K are scanned by the light beam RY to the light beam RK. This range is regulated both in the width direction and the length direction of the paper S.

  Therefore, since toner does not adhere to the shaded area in FIG. 11, even if image data having an area having a width and length larger than the sheet width PS is input, the sheets on the photosensitive drum 36Y to the photosensitive drum 36K. Toner does not adhere to the area corresponding to the peripheral edge of S and the outside thereof.

  Therefore, even if a standard paper s larger in size than the paper S is fed after a region where the toner has not been transferred to the paper S occurs in the photosensitive drum 36Y to the photosensitive drum 36K, the peripheral portion of the standard paper s remains. There is no stain with toner. Further, the toner remaining on the surfaces of the photosensitive drums 36Y to 36K is not mixed into the developing units 35Y to 35K that develop with different color toners, and color mixing does not occur.

FIG. 1 is a schematic explanatory diagram illustrating the internal structure of the printer according to the first embodiment. FIG. 2 is a plan view showing details of the configuration of an example of a paper guide and a scanning width limiting member provided in the printer according to the first embodiment. FIG. 3 is a plan view showing the details of the configuration of another example of the paper guide and the scanning width limiting member provided in the printer according to the first embodiment. FIG. 4 is an explanatory diagram showing the relationship between the interval between the sheet width limiting members and the sheet width. FIG. 5 is an explanatory diagram showing a light shielding area and an exposure area on the photosensitive drum of the printer according to the first embodiment. FIG. 6 is an explanatory diagram showing the internal structure of the printer according to the second embodiment and the configuration of the paper detection lever 26 and shutter 24 of the printer. FIG. 7 is an explanatory diagram illustrating a state where the shutter included in the printer according to the second embodiment is opened and closed. FIG. 8 is an explanatory diagram showing a light shielding area and an exposure area on the photosensitive drum of the printer according to the second embodiment. FIG. 9 is a schematic explanatory diagram illustrating the internal structure of the full-color printer according to the third embodiment. FIG. 10 is an explanatory diagram illustrating a positional relationship between a scanning width limiting member and a shutter included in the full-color printer according to the third embodiment. FIG. 11 is an explanatory diagram showing a light shielding area and an exposure area on the photosensitive drum of the printer according to the third embodiment.

Explanation of symbols

2 Manual feed tray 4 Image forming transfer unit 6 Photosensitive drum 8 Optical scanning device 10 Scanning width limiting member 10A Shading plate 10B Link unit 10 Link unit 14 Link mechanism 14A First arm member 14B Second arm member 14C Connection member 14D Connection member 15A Rotating shaft 15B Rotating shaft 16 Conveying roller 18 Fixing unit 22 Manual feed tray 24 Shutter 24A Fixed plate 24B Movable plate 24C Slit 24D Slit 26 Paper detection lever 27 Spring 28 Registration sensor 32 Manual feed tray 33 Paper guide 34 Image formation transfer unit 35Y Development Device 35M developing device 35C developing device 35K developing device 36Y photosensitive drum 36M photosensitive drum 36C photosensitive drum 36K photosensitive drum 37A primary transfer drum 37B primary transfer drum 38 secondary transfer drum 38 secondary transfer roller 39 final transfer roller 40 optical scanning device 50 Scanning width limiting member 52 Link mechanism 60 Shutter 62 Shutter opening / closing means 64 Registration sensor 70 Fixing unit 80 Paper tray 90 Stacking unit 92 Conveying roller pair 94 Outlet side roller pair 97 Feed roller pair 98 Conveying roller pair 100 Printer 102 Printer 104 Full color Printer L3 distance

Claims (8)

A latent image is formed by scanning the surface of the photosensitive member with a light beam emitted from an optical scanning device, and the toner image formed by developing the latent image with toner is transferred to a sheet and fixed to form an image. An image forming apparatus having a manual feed tray for feeding the paper into the image forming apparatus,
Paper width detecting means for detecting the width of the paper fed from the manual feed tray;
Scanning width limiting means for limiting the width along the main scanning direction of the scanning region in which the light beam scans the photoconductor so as not to exceed the width of the paper detected by the paper width detecting means;
An image forming apparatus comprising the image forming apparatus. The scanning width limiting means includes a pair of scanning width limiting members disposed on both sides of the optical path of the light beam and limiting the scanning width by blocking the light beam,
The distance between the scanning width limiting members is W1, the distance from the photoconductor to the scanning width limiting member is L1, the paper width detected by the paper width detecting means is PS, and the light beam at the end of the scanning area When the scanning angle that is an angle formed between the surface of the photosensitive member and the photosensitive member surface is θ, the interval W1 between the scanning limiting members is
W1 ≦ PS-2 × L1 × tan θ
The image forming apparatus according to claim 1, wherein the relationship is set so that The scanning width limiting means includes one scanning width limiting member that is disposed on one side of the optical path of the light beam and limits the scanning width by blocking the light beam, and the scanning is performed from the center of the optical path of the light beam. When the distance to the width limiting member is W2, and the distance from the photoconductor to the scanning width limiting member is L2,
W2 ≦ PS / 2−L2 × tan θ
The image forming apparatus according to claim 1, wherein the position of the scanning width limiting member is set so that   The paper width detecting means is a paper guide that guides the paper in the manual feed tray and is movable in the width direction of the paper according to the width of the paper, and the scanning width limiting member is interlocked with the paper guide. The image forming apparatus according to claim 1, wherein the image forming apparatus moves along a scanning direction of the light beam. A latent image is formed by scanning the surface of the photosensitive member with a light beam emitted from an optical scanning device, and the toner image formed by developing the latent image with toner is transferred to a sheet and fixed to form an image. An image forming apparatus having a manual feed tray for feeding the paper into the image forming apparatus,
A shutter located on the optical path of the light beam, shutter opening / closing means for opening / closing the shutter, and paper detection means for detecting paper inserted in the manual feed tray,
The image forming apparatus according to claim 1, wherein the shutter opening / closing means opens the shutter for a time during which the paper detection means detects the paper. A latent image is formed by scanning the surface of the photosensitive member with a light beam emitted from an optical scanning device, and the toner image formed by developing the latent image with toner is transferred to a sheet and fixed to form an image. An image forming apparatus having a manual feed tray for feeding the paper into the image forming apparatus,
A shutter located on the optical path of the light beam, shutter opening / closing means for opening / closing the shutter, and paper detection means for detecting paper inserted in the manual feed tray,
The shutter opening / closing means stores a time required for the paper to pass through the paper detection means, and opens the shutter based on the time so that an exposure time on the photoconductor does not exceed the stored time. An image forming apparatus. Paper width detecting means for detecting the width of the paper fed from the manual feed tray;
Scanning width limiting means for limiting the width along the main scanning direction of the scanning region in which the light beam scans the photoconductor so as not to exceed the width of the paper detected by the paper width detecting means;
An image forming apparatus according to claim 5 or 6 provided. The scanning width limiting means includes a pair of scanning width limiting members that are disposed on both sides of the optical path of the light beam and limit the scanning width by blocking the light beam, from the center of the optical path of the light beam. When the distance to the scanning width limiting member is W2 and W2 ′, respectively, and the distance from the photoconductor to the scanning width limiting member is L2 and L2 ′, respectively,
W2 ≦ PS / 2−L2 × tan θ
W2 ′ ≦ PS / 2−L2 ′ × tan θ
The image forming apparatus according to claim 1, wherein the position of the scanning width limiting member is set so that

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