JP4637597B2 - Duplex printing device - Google Patents

Description

The present invention relates to a duplex printing apparatus used in an image forming apparatus such as a copying machine, a printer, or a facsimile machine using an electrophotographic process.

Generally, as an image forming apparatus, after image formation (printing) is performed on one side (first surface) of a recording sheet (hereinafter simply referred to as a sheet) in an image forming unit, the image-formed sheet is reversed, There is known an image forming apparatus that transports the image again to the image forming unit and forms an image on both sides of the sheet by forming an image on the other side (second side) of the sheet.

To perform double-sided printing, the image forming apparatus is equipped with a double-sided printing device (double-sided printing unit), and in double-sided printing mode, paper on which an image has been formed on one side is sent to the double-sided printing unit. Then, the sheet is sent again to the image forming unit to form an image on the other side. In such a double-sided printing unit, the paper on which an image is formed on one side is once transported to an intermediate tray (width-adjusting tray) provided in the double-sided printing unit, where the width of the paper is adjusted by a width-adjusting guide. Then, the paper is reversed and sent to the image forming unit again.

The intermediate tray unit has a tray casing and a width alignment guide, and moves the width alignment guide by moving the width alignment guide in a direction orthogonal to (intersects) the paper conveyance direction. In such a case, rubbing between the tray housing and the width matching housing and noise due to rubbing are generated. In order to reduce such friction and noise, the tray housing is made of resin and the width alignment guide is made of metal.

In other words, the width alignment guide is in an electrically floating state, and in the duplex printing unit, static electricity generated due to the friction between the paper and the width alignment guide is accumulated in the width alignment, There is a phenomenon that the paper sticks to the width alignment guide due to the action of static electricity. Then, if the paper sticks to the width alignment guide, a problem occurs in the width alignment and conveyance of the paper.

On the other hand, in a copying machine capable of duplex copying, a presser plate that swings up and down is disposed on the upper surface of the intermediate tray formed of a non-conductive material in order to remove static charges from the copy paper stored in the intermediate tray section. Then, a neutralizing member made of conductive fibers is attached to the lower surface of the sheet. Each time a copy sheet is loaded into the intermediate tray, the holding plate is swung up and down to press the copy sheet against the intermediate tray. The charge removal member on the lower surface comes into contact with the copy paper to remove the charge remaining on the copy paper. Furthermore, when the presser plate moves away from the copy paper, a discharge is generated to remove the charge remaining on the copy paper. (See Patent Document 1).

JP-A-5-213470

By the way, in Patent Document 1, a presser plate that swings up and down is arranged on the upper surface of the intermediate tray, and a neutralizing member made of conductive fibers is stuck on the lower surface thereof, and one copy sheet is carried into the intermediate tray. Each time the press plate is swung up and down, the copy paper is pressed against the intermediate tray, and the charge removal member on the bottom of the press plate comes into contact with the copy paper to remove the charge remaining on the copy paper. There is a problem that the press plate is disposed on the upper surface of the intermediate tray, and the press plate must be swung every time a copy sheet is carried into the intermediate tray, which complicates the configuration. .

Furthermore, in Patent Document 1, although static charge can be removed from the copy paper, it is difficult to remove static electricity accumulated in the width alignment guide, and static electricity is not removed from the width alignment guide. If static electricity is accumulated in the guide, there is a problem that the width adjustment and conveyance of the sheet become defective as described above.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a double-sided printing apparatus capable of removing static electricity from a width alignment guide with a simple configuration in view of the problems of the prior art.

Therefore, in order to solve the problem, the present invention includes an image forming unit that forms an image on a recording sheet, and the recording sheet that is disposed on the downstream side of the image forming unit and on which the image is formed by the image forming unit. Both sides used together with an image forming apparatus having a fixing device for fixing, receiving a recording sheet on which an image is formed on one side through the fixing unit, reversing the surface of the recording sheet and sending it to the image forming unit A printing apparatus, comprising: an intermediate tray portion that feeds the recording paper in a direction opposite to a loading direction after the recording paper is carried in and the width of the recording paper is adjusted, and the intermediate tray portion is at least non-conductive Tray housing, a pair of conductive width adjusting guides disposed in the tray housing and movable in a direction intersecting the carrying-in direction, and a position where the distance between the width adjusting guides is the largest. The width adjustment guide and the width adjustment guide position is located and a contact with the conductive member, the conductive member is characterized in that it is grounded. The width alignment guide is positioned at the home position, for example, between sheets.

In the present invention, the tray casing includes a base plate, and each of the width alignment guides is attached to a bottom plate portion positioned in a state parallel to the base plate and a width direction outer end of the base plate, and the bottom plate And the conductive member is attached to each of both end portions in the width direction of the base plate so as to face the rising side portion, and one end of the conductive member is the rising position at the home position. The base plate is positioned on the inner side in the width direction of the base plate.

In the present invention, the conductive member includes, for example, a spring member, and one end of the spring member is positioned on the inner side in the width direction of the base plate than the position of the rising side portion at the home position.

As described above, in the duplex printing apparatus according to the present invention, when the width alignment guide is positioned at the home position where the interval between the width alignment guides is the largest, the grounded conductive member is brought into contact with the width alignment guide. Therefore, it is possible to discharge static electricity accumulated in the conductive width adjusting guide disposed in the non-conductive tray casing, and it is easy to simply provide a conductive member in the tray casing. With this structure, there is an effect that static electricity can be removed from the width alignment guide.

In the present invention, the conductive members are respectively attached to both side end portions in the width direction of the base plate, and one end of the conductive member is opposed to the rising side portion inwardly in the width direction of the base plate from the position of the rising side portion in the home position. Since they are positioned, there is an effect that the conductive member can be brought into contact with the width alignment guide with a simple configuration.

In the present invention, the conductive member has a spring member, and one end of the spring member is positioned on the inner side in the width direction of the base plate from the position of the rising side at the home position. When positioned, the spring member is pressed at the rising side portion, and the spring member presses the rising side portion, so that there is an effect that the contact between the conductive member and the width alignment guide can be improved.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention unless otherwise specified, but are merely illustrative examples. Not too much.

  First, referring to FIG. 1, the illustrated image forming apparatus is an image forming apparatus using an electrophotographic process, and the image forming apparatus 10 includes an image forming unit (image forming unit) 12 including a photosensitive drum 11. Sheets are selectively sent from the plurality of sheet feed cassettes 13 to 15 to the image forming unit 12 via the sheet transport path 16 (for example, sheets of different sizes are stored in the sheet feed cassettes 13 to 15. ) An electrostatic latent image corresponding to the image information is formed on the photosensitive drum 11 by the exposure unit 17, and the electrostatic latent image is developed to form a toner image on the photosensitive drum 11.

A toner image is transferred from the photosensitive drum 11 to one side of the sheet sent to the image forming unit 12, and this sheet is sent to the fixing device 19 via the sheet conveyance path 18, where the toner image on the sheet is transferred to the image forming unit 12. It is fixed. As shown in the figure, a double-sided printing device (double-sided printing unit) 20 is disposed between the paper feed cassette 13 and the image forming unit 12.

When the single-sided printing mode is selected on an operation panel (not shown) provided in the image forming apparatus 10, the path switching member 21 positioned at the subsequent stage of the fixing device 19 becomes the single-sided printing position and is sent from the fixing device 19. The discharged paper is discharged to the paper discharge tray 22. On the other hand, when the duplex printing mode is selected on the operation panel, the path switching member 21 becomes the duplex printing position, and the sheet sent from the fixing device 19 is conveyed into the duplex printing unit 20.

The double-sided printing unit 20 is provided with an intermediate tray unit 23, which will be described later, and the paper carried into the double-sided printing unit 20 is subjected to width alignment at the intermediate tray unit 23 as described later, The paper is sent from the tray unit 23 and is sent to the paper transport path 16 through the reverse path shown by the broken line 24 in the figure in the inverted state, and the paper is sent again to the image forming unit 12 through the paper transport path 16. Thus, the toner image on the photosensitive drum 11 is transferred to the other surface of the sheet and fixed by the fixing device 19. Then, the paper subjected to double-sided printing is discharged to the paper discharge tray 22 by the path switching member 21 that has returned to the single-sided printing position.

Referring also to FIG. 2, FIG. 2 is a diagram showing the double-sided printing unit 20, and the paper carried into the double-sided printing unit 20 side by the path switching member 21 is guided by the feed roller 20c through the paper transport path 20a. When the rear end of the paper leaves the feed roller 20c, the guide plate 20b rotates counterclockwise and is adjusted by the width adjusting guides 23a and 23b provided in the intermediate tray 23. The width is adjusted.

When the width adjustment is performed, the forward feed roller 20d descends to feed the paper in the direction opposite to the carry-in direction, and the paper is sent from the intermediate tray portion 23 by the transport roller 20e. Then, the sheet is guided by the guide plate 20b and sent out to the reverse path 24 by the roller 20f and the belt 20g.

With reference to FIGS. 3-5, the structure of the intermediate tray part 23 is demonstrated in detail. The intermediate tray unit 23 includes a tray housing (not shown). A base plate 31 is fixed to the tray housing, a push-up plate 32 is disposed with respect to the base plate 31, and the push-up plate 32 is re-transferred. The tip is pushed up. Further, as described above, the intermediate tray portion 23 has the width alignment guides 23a and 23b and the rack and pinion mechanism 33 for moving the width alignment guides 23a and 23b.

The rack and pinion mechanism 33 includes a pinion 33a and a pair of racks 33b and 33c that mesh with each other in parallel with each other. Together, the end portions are fixed to the width alignment guides 23a and 23b, respectively, and the interval between the width alignment guides 23a and 23b is adjusted according to the width of the sheet by the rotation of the pinion 33a.

As shown in the figure, the width alignment guides 23a and 23b have horizontally disposed bottom plate portions 34 and 35, and rising side portions 36 and 37 that rise upward at their ends (outer ends in the width direction of the base plate 31). The base portions (slider portions) 331 and 332 of the racks 33b and 33c are fixed to the screw holes formed in the bottom plate portions 34 and 35 by the countersunk screws 38 and 39, and are pivotally supported directly below the countersunk screws 38 and 39. While the rollers 42 and 43 are slidably fitted into the guide groove 44 of the guide member 33d, the rising side portions 36 and 37 are protruded upward from the cutout portions 40 and 41 formed on both sides of the push-up plate 32. The detected element 4 for detecting the home position (standby position) at the position on the axis G of the pinion 33a in the rising side portion 37 of the one width adjusting guide 23b. To form.

The home position refers to a position where the distance adjustment guides 23a and 23b move in the width direction of the base plate 31 and the interval between them is the largest.

And the position of the to-be-detected child 45 is detected with the detection sensor 46 provided in the side part 31a of the baseplate 31. FIG. In addition, a sensor escape hole 47 is formed immediately below the detected element 45 to increase the moving distance of the width alignment guides 23a and 23b, thereby reducing the size of the intermediate tray portion 23. Further, a long hole 48 is formed in the base plate 31 to allow the rollers 42 and 43 to move. The pinion 33a is rotationally driven by a motor (not shown) provided below the base plate 31 via a gear transmission mechanism.

Incidentally, as described above, in order to reduce rubbing and noise due to rubbing when the width adjusting guides 23a and 24b are moved, for example, the base plate 31 and the push-up plate 32 constituting a part of the tray housing are made of resin. The width alignment guides 23a and 23b are made of metal. As a result, the width alignment guides 23a and 23b are in an electrically floating state, and static electricity generated due to the friction between the paper and the width alignment guides 23a and 23b is accumulated in the width alignment, Problems occur in the width alignment and conveyance of the paper.

Here, in order to prevent such a problem, the configuration shown in FIG. 6 was adopted. 6, the same reference numerals are given to the same components as those shown in FIGS. 3 to 5 (in FIG. 6, the racks 33 b and 33 c and the rollers 42 and 43 are not shown, and the slider Only parts 331 and 332 are shown). Referring to FIG. 6, a conductive support member 61 is attached to the side portion 31 a of the base plate 31, and the support member 61 extends in the width direction of the base plate 31. A conductive terminal piece 62 is attached to one end (left end in the figure) of the support member 61, and this terminal piece 62 extends in the paper transport direction.

One end of a conductive coil spring (conductive member) 63 is attached to the tip of the terminal piece portion 62. This coil spring 63 extends in the width direction of the base plate 31 and faces the rising side portion 37 of the width alignment guide 23b. Yes. The support member 61 is connected to a ground terminal (not shown) provided in the image forming apparatus.

On the other hand, in the illustrated example, one end of a conductive coil spring 64 is directly attached to the side portion 31 b of the base plate 31, and the coil spring 64 extends in the width direction of the base plate 31. The coil spring 64 faces the rising side portion 36 of the width alignment guide 23a. The coil spring 64 is connected to a ground terminal provided in the image forming apparatus.

Since the detection sensor 46 is disposed on the side 31a side of the base plate 31, the rising edges of the side 31a and the width alignment guide 23b even when the width alignment guides 23a and 23b are positioned at the home position. Since the distance to the portion 37 is long, the support member 61 and the terminal piece portion 62 are used on the side portion 31a side.

As described above, in the duplex printing mode, a sheet on which single-sided printing has been performed is carried into the intermediate tray unit 23. At this time, the width adjustment guides 23a and 23b are driven in the intermediate tray unit 23. Then, the width of the paper is adjusted, and the paper is sent in the direction opposite to the paper carry-in direction. The width alignment guide 23a is positioned at the home position until the next sheet is carried in (that is, between the sheets).

The tips of the coil springs 64 and 63 are located inside the positions of the rising edges 36 and 37 of the width alignment guides 23a and 23b at the home position, and as a result, the width alignment guides 23a and 23b are positioned at the home position. Then, the coil springs 64 and 63 are pressed outward in the width direction by the rising side portions 36 and 37, and the coil springs 64 and 63 are in contact with the rising side portions 36 and 37, that is, the width adjusting guides 23a and 23b. Static electricity accumulated in 23a and 23b is discharged to the ground terminal side of the image forming apparatus.

It is to be noted that the carry-in of the paper into the intermediate tray portion 23 is detected by a paper detection sensor (not shown), and the control device provided in the image forming apparatus until the paper is detected by the paper detection sensor, the width adjusting guide 23a and 23b is positioned at the home position.

In the above-described example, after one sheet is loaded into the intermediate tray unit 23 and sent in the reverse direction, the width alignment guides 23a and 23b are set to the home position while the next sheet is loaded into the intermediate tray unit 23. For example, when small-sized sheets continue, the width alignment guides 23a and 23b are positioned at the home position for each preset number of sheets and accumulated in the width alignment guides 23a and 23b. Static electricity may be discharged to the ground terminal via the coil springs 64 and 63.

As described above, when the width adjusting trays 23a and 23b are positioned at the home position, the width adjusting trays 23a and 23b are grounded via the coil springs 64 and 63. Is not accumulated, and only the coil springs 64 and 63 need be provided, so that static electricity can be removed from the width alignment guides 23a and 23b with a simple configuration.

When the width alignment guide is positioned at the home position where the distance between the width alignment guides is the largest, the grounded conductive member is brought into contact with the width alignment guide. As a result of being able to discharge static electricity accumulated in the conductive width alignment guide disposed in the housing, the invention can be applied to a double-sided printing apparatus having a non-conductive device housing and a conductive width alignment guide.

1 is a diagram schematically illustrating an example of an image forming apparatus in which a double-sided printing apparatus according to a first embodiment of the present invention is used. It is a figure which shows the double-sided printing apparatus shown in FIG. 1 in detail. FIG. 3 is a plan view of an intermediate tray portion shown in FIG. 2. It is a top view which shows the width alignment guide in the intermediate tray part shown in FIG. FIG. 3 is a perspective view showing a rack and pinion mechanism used in the intermediate tray portion shown in FIG. 2. It is a top view for demonstrating the mechanism which discharges the static electricity accumulate | stored in the width alignment guide in the intermediate tray part shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 11 Photosensitive drum 12 Image formation part (image formation unit)
13 to 15 Paper feeding cassette 19 Fixing device 20 Duplex printing device (duplex printing unit)
22 Discharge tray 23 Intermediate tray portions 23a and 23b Width alignment guide 31 Base plates 34 and 35 Bottom plate portions 36 and 37 Rising edge portion 45 Detector 46 Detection sensor 63 and 64 Coil spring

Claims (4)

The image forming apparatus includes an image forming unit that forms an image on a recording sheet, and a fixing device that is disposed on the downstream side of the image forming unit and fixes the recording sheet on which the image is formed by the image forming unit. A double-sided printing apparatus that receives the recording paper on which the image is formed on one side through the fixing device, reverses the surface of the recording paper, and sends the recording paper to the image forming unit,
An intermediate tray for feeding the recording paper in a direction opposite to the carrying-in direction after the recording paper is carried in and the recording paper is adjusted in width;
The intermediate tray portion is at least a non-conductive tray casing and a pair of conductive width adjusting guides disposed in the tray casing and movable in a direction intersecting the loading direction;
A conductive member that comes into contact with the width alignment guide when the width alignment guide is positioned at a home position where the interval between the width alignment guides is the largest;
The double-sided printing apparatus, wherein the conductive member is grounded. 2. The duplex printing apparatus according to claim 1, wherein the width alignment guide is positioned at the home position between sheets. The tray casing has a base plate,
Each of the width alignment guides has a bottom plate portion positioned in a state parallel to the base plate and a rising side portion that is attached to the outer end in the width direction of the base plate and stands upright from the bottom plate portion,
The conductive members are respectively attached to both end portions in the width direction of the base plate and face the rising side portion, one end of which is inward in the width direction of the base plate from the position of the rising side portion in the home position. The double-sided printing apparatus according to claim 1, wherein the double-sided printing apparatus is located in The double-sided printing according to claim 3, wherein the conductive member has a spring member, and one end of the spring member is located on the inner side in the width direction of the base plate than the position of the rising side portion at the home position. apparatus.

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