JP2010215378A - Sheet conveying device, image reader, and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sheet conveying device, an image reader, and an image forming device therewith which are of high quality at a moderate price. <P>SOLUTION: The sheet conveying device that conveys a sheet S from conveying means 17a, 17b to a sheet conveying region J and corrects a skew by a skew correcting means A1 includes: a first guide means 80 having a bent portion 81 in which the skew correcting means projects toward the sheet conveying region; and a second guide means 70 having a bent portion 71 that projects toward the sheet conveying region. A detecting means 36 for detecting a sheet end is provided at a detection position in the vicinity of a downstream of the bent portion 71 in the sheet conveyance direction. The first guide means 80 and the second guide means 70 are provided to simultaneously bring into contact with the bent portion 81 and the bent portion 71 positioned on the downstream of the bent portion 81 when the sheet S is detected by the detecting means 36. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a sheet conveying apparatus, an image reading apparatus, and an image forming apparatus, and more particularly to a configuration for correcting skew of an image forming medium such as a recording sheet or a document conveyed to an image forming unit or an image reading unit. Image of a sheet transport apparatus provided, a copier equipped with the sheet transport apparatus, a facsimile, a printer, a printing machine, an ink jet recording apparatus, an image reading apparatus such as a scanner, or a composite machine combining at least two of them The present invention relates to a forming apparatus.

  2. Description of the Related Art Conventionally, in image forming apparatuses and image reading apparatuses such as copying machines, facsimile machines, printers, printing machines, and ink jet recording apparatuses, sheet-like recording media or bag-like recording media (image forming media) that are media on which images are formed ( A sheet conveying apparatus is provided for conveying and supplying a sheet from a sheet storage unit or a sheet stacking unit for stacking sheets to the image forming unit main body.

  Note that image forming apparatuses are generally compatible with various sizes and sheet types (hereinafter, “paper types”). In such an image forming apparatus model, for example, sheets of several sizes and paper types are stored in advance in the sheet storage unit, and the sheet is stored in the sheet storage unit appropriately selected by the user, or image formation is performed. The device can feed automatically selected sheets.

  Therefore, in such a configuration, since the sheet storage unit occupies more space in the image forming apparatus, it is necessary to reduce the size of the conveyance unit, and the sheet conveyance of such a conveyance unit is increased. The road tends to be relatively short. Some of them include skew correction means for correcting the posture of the sheet and adjusting the position of the sheet on such a sheet conveyance path.

  In this skew feeding correcting means, a stopped registration roller pair having a nip perpendicular to the sheet conveyance path is arranged in the middle of the sheet conveyance path, and the leading edge of the sheet being conveyed is abutted against the nip of the registration roller pair to the sheet. Then, the sheet tip is made to follow the nip parallel to the nip by the elasticity of the sheet itself, thereby correcting the sheet tip perpendicular to the sheet conveying direction, that is, skew correction. When the deflection of the sheet reaches a predetermined amount, if the registration roller pair is rotated, the leading edge of the sheet is conveyed to the registration roller pair while maintaining the vertical direction with respect to the sheet conveyance direction. Is conveyed to the image forming unit.

  By the way, the sheet conveying path is arranged in the order of the sheet conveying means, the sheet leading edge detecting means, and the registration roller pair along the sheet conveying direction. The amount of bending of the sheet is determined after the sheet leading edge reaches the registration roller pair. It is determined by the time until the registration roller pair rotates, and is substantially determined by the sheet conveying speed of the sheet conveying unit and the time from when the sheet leading end detecting unit detects the sheet leading end until the roller pair driving unit operates. Is done.

  In the skew correction means, if the amount of deflection of the sheet fluctuates from the appropriate amount, the abutting force is insufficient and the skew correction is insufficient, or conversely, if the abutting force is excessive, the sheet buckles. Occur. For this reason, in the sheet conveying apparatus having the skew feeding correcting means, it is required to accurately detect the leading edge of the sheet being conveyed.

  Patent Document 1 (Japanese Patent Application Laid-Open No. 11-292353) discloses a sheet conveying apparatus in which a sheet is not damaged by a bent portion of an upper guide plate 5. This sheet conveying apparatus will be described with parentheses attached to the reference numerals shown in the respective drawings of Patent Document 1. The sheet is moved up and down by an intermediate roller pair (1) provided in the sheet conveying path (4, 5), the leading edge of the sheet collides with the lower guide plate (4a) and changes its direction, and then the leading edge of the sheet contacts the registration roller pair (2) and is bent downward. The sheet is conveyed to the transfer unit (7) by driving the registration roller pair (2) and the intermediate roller pair (1) while maintaining the bending, and the sheet is damaged by the bent portion of the upper guide plate (5). Disclosed is a sheet conveying apparatus in which there is no occurrence.

  By the way, in recent years, various types of sheets such as a sheet-like recording medium or a bag-like recording medium have come to be used in apparatuses equipped with a mechanism for conveying sheets, such as an image forming apparatus. For example, in the medical field, the demand for forming an image using an image forming apparatus on a medicine bag which is a bag-shaped sheet as a recording medium is rapidly increasing.

  For example, as shown in FIGS. 14A and 14B, the bag-shaped sheet S1 that is a recording medium has three sides (a maximum of two sheets) having a three-side glued portion q in which two sheets of paper are bonded together. There is a two-sided glue bag Sb having a structure (a maximum of two sheets) having a two-side glued portion q1 in which a sheet of paper is bonded in a cylindrical shape. Further, as shown in FIGS. 15A to 15C, a structure having a horizontal gusset m in which two sheets of paper are bonded together (up to four sheets stacked) (the number of stacks shown in the figure is indicated numerically). There is a gusseted medicine bag Sc. Further, as shown in FIGS. 16A to 16C, a single sheet of paper is laminated in a cylindrical shape and bent at six locations to form horizontal gussets m1 and m1, and further, the bottom is bent to form the corner bottom 51 and There is a square-bottom medicine bag Sd of up to 12 sheets (the number of overlaps shown in the figure as a numerical value) in which the folded portion 53 is formed.

  In these bag-shaped sheets S1, not only the thickness of one sheet is large, but also the thickness deviation caused by the difference in the number of stacked sheets in one sheet, the thickness deviation of the glued portion q, the bent portion The deviation of the crushing condition is irregularly distributed, and the deviation of stiffness (bending rigidity) is very large.

  As described above, a large stiffness deviation is distributed in one sheet in the bag-shaped sheet S1. When the bag-shaped sheet S1 is conveyed by the image forming apparatus, there is a variation in the stiffness of the individual sheets accompanying the conveyance, and the contact state with the guide portion is different, so that the leading edge of the sheet vibrates and flickers easily occur.

  Therefore, Patent Document 2 (Japanese Patent Laid-Open No. 2006-341935) discloses a sheet feeding apparatus and a sheet processing apparatus, and these apparatuses are described with parentheses attached to the reference numerals shown in the drawings of Patent Document 2. To do. Here, when the sheet detection unit (307) detects the leading edge of the fed sheet, the conveyance unit position (302, 304) sandwiches the sheet and the sheet regardless of the path of the fed sheet. The distance from the tip of the lens is constant (R). As a result, it is assumed that curling or fluttering of the sheet leading edge occurs in the conveying path (T) having a predetermined gap, and the leading edge position of the sheet is accurately detected even when the sheet path is shifted in the height direction. Can do.

  Further, Patent Document 3 (Japanese Patent Application Laid-Open No. 2004-338923) discloses a sheet conveying apparatus, and this apparatus will be described with parentheses attached to the reference numerals shown in the drawings of Patent Document 3. Here, the outer and inner center guide portions (304, 306) are provided in a protruding manner on the center side of the transport path of the upper and lower transport guide portions (303b, 303a) to narrow the gap in the center portion in the width direction of the sheet transport path, and the width The gap at both ends is widened. Accordingly, the skew correction accuracy of the sheet can be improved by reducing the load received from the conveyance guide unit when the skew correction unit (20A, 20B) rotates the sheet to correct the skew.

As described above, in a sheet conveying apparatus having a skew feeding correcting means, it is required to accurately detect the leading edge of the sheet being conveyed.
However, when the bag-shaped sheet S1 is conveyed by the sheet conveying apparatus having the skew feeding correcting means, the bag-shaped sheet is large in thickness, strong in stiffness (bending rigidity), and a large stiffness deviation is distributed in one sheet. For example, a bag-shaped sheet such as a square bottom medicine bag has the following problems.

  That is, when a bag-shaped sheet is conveyed by the sheet conveying apparatus, there is a variation in the sheet stiffness accompanying the conveyance, and as a result, a flutter occurs between the leading edge of the conveyed sheet and the guide, and the leading edge of the sheet As a result, the position detection accuracy will decrease, resulting in the sheet deflection amount deviating from the proper amount, and the abutting force will be insufficient, causing skew correction to be insufficient, or conversely, the abutting force will be excessive. Then, the buckling of the sheet will occur.

In order to prevent the occurrence of such a problem, a sheet conveying apparatus having a skew feeding correcting means is required to accurately detect the leading edge of the sheet being conveyed.
However, in the case of the sheet conveying device disclosed in Patent Document 1 described above, when passing between the guide plate 4 and the guide plate 5, the sheet leading edge is twisted because it moves randomly in the vertical gap between the two guide plates. The deviation in the conveyance resistance is caused by the displacement in the vertical direction, and the accuracy of the detection position of the registration sensor is lowered. In particular, even in the case of a very strong sheet such as a medicine bag, even if the guide plate bends in the vertical direction, the amount of bending and the local folding position occur irregularly, and the accuracy of the detection position of the registration sensor decreases. Due to this, there is a tendency for the leading edge margin to vary from sheet to sheet.

  Further, in the sheet feeding apparatus disclosed in the above-mentioned Patent Document 2, skew is detected by the leading edge of the sheet contacting the sheet detecting means. When a bag-shaped sheet having a non-uniform thickness and large stiffness variation is guided to such a sheet detecting means, the platen (303), which is a guide means, passes through a bent path on the upstream side of the conveying path. Further, when reaching the opening of the pinch roller holder (305), there is a problem that the sliding resistance is large, and the pinch roller holder (305) may not be able to move inside than the opening of the guide means, and the configuration becomes complicated.

  Further, in the case of the sheet conveying apparatus disclosed in Patent Document 3 described above, the contact state of the guide portion is different at the leading edge of the sheet being conveyed, so that the leading edge of the sheet vibrates and the detection accuracy of the sheet leading edge detection sensor is reduced. It is easy to generate. In this case, skew correction is insufficient due to a decrease in detection accuracy of the sheet leading edge, leading edge variation for each sheet occurs, and sheet buckling occurs.

  As a means of preventing a decrease in detection accuracy, a method of increasing the waiting time is also known, but in order to respond to recent demands for speeding up and downsizing, it is necessary to reduce the waiting time. It is pressed. However, as the waiting time is shortened, the sheet leading edge detection accuracy is lowered as described above, and the degree of influence on the quality of the skew correction function is increasing.

  Accordingly, the present invention has been made in view of the above-described circumstances, and is an inexpensive, high-quality sheet conveying apparatus, image reading apparatus, and image forming apparatus having the same in order to solve the problems and problems described above. The purpose is to provide.

  In order to solve the above-described problems and achieve the above-mentioned object, the invention according to each claim employs the following characteristic means / invention-specific matters (hereinafter referred to as “configuration”).

  The invention according to claim 1 is a sheet conveying apparatus that conveys a sheet from the conveying means to the sheet conveying area and corrects the skew by the skew correcting means, wherein the skew correcting means protrudes into the sheet conveying area. A first guide means having a portion and a second guide means having a bent portion extending opposite to the first guide means and protruding to the sheet conveying area, and conveying the sheet at the bent portion of the second guide means Detection means for detecting the leading edge of the sheet is disposed at a detection position near the downstream in the direction, and when the sheet is detected by the detection means, the bent portion of the first guide means and the second guide downstream of the bent portion. The first guide means and the second guide means are arranged so as to be in contact with the bent portion of the means at the same time.

  According to a second aspect of the present invention, in the sheet conveying apparatus according to the first aspect, when the sheet passes through the bent portions of the first guide means and the second guide means in the sheet conveying direction, A gap is maintained between the facing wall disposed opposite to the portion and the sheet.

  According to a third aspect of the present invention, in the sheet conveying apparatus according to the first or second aspect, the sheet conveying area includes a registration roller pair on the downstream side of the second guide unit, and the upstream side of the registration roller pair. The detecting means is provided.

  According to a fourth aspect of the present invention, in the sheet conveying apparatus according to the first, second, or third aspect, either the first guide unit and the second guide unit, or the first guide unit and the second guide unit. It has a friction reducing member on one surface.

  According to a fifth aspect of the present invention, in the sheet conveying apparatus according to any one of the first to fourth aspects, both the first guide means and the second guide means, or the first guide means and the second guide. One of the means is characterized in that one bent portion is formed at the outer peripheral portion of the rotating member.

  According to a sixth aspect of the present invention, in the sheet conveying apparatus according to the fifth aspect, the rotating member has a driving unit.

  According to a seventh aspect of the invention, in the sheet conveying apparatus according to any one of the first to sixth aspects, the bent portion of the second guide means has a rib.

  According to an eighth aspect of the present invention, in the sheet conveying apparatus according to any one of the first to seventh aspects, the second guide means is rotatable and has a mounting portion for the detection means. .

  According to a ninth aspect of the present invention, in the sheet conveying apparatus according to any one of the first to eighth aspects, the conveying unit is wider than a sheet width in a direction perpendicular to the sheet conveying direction.

  A tenth aspect of the present invention is the sheet conveying apparatus according to any one of the first to ninth aspects, wherein the conveying means is a pair of rollers having the same hardness.

  According to an eleventh aspect of the present invention, there is provided an image forming apparatus including the sheet conveying apparatus according to any one of the first to tenth aspects.

  According to a twelfth aspect of the present invention, there is provided an image reading apparatus comprising the sheet conveying apparatus according to any one of the first to tenth aspects.

  A thirteenth aspect of the invention is an image forming apparatus including the sheet conveying device according to any one of the first to tenth aspects or the image reading device of the twelfth aspect.

  According to a fourteenth aspect of the present invention, in the image forming apparatus according to the thirteenth aspect, the image forming apparatus is one of a copying machine, a facsimile machine, a printer, a printing machine, and an ink jet recording apparatus, or at least two of them. It is a combined multifunction device.

The effects of the above-described configuration of the present invention are as follows.
According to the present invention, when the leading edge of the sheet moves to the detection position, the sheet is simultaneously moved along the sheet conveying direction at three positions, that is, the sheet conveying means, the bent portion of the first guide means, and the bent portion of the second guide means. At the same time, the posture is regulated, in particular, the vertical position of the sheet tip is regulated, vibration of the sheet tip and occurrence of fluttering are suppressed, and the sheet tip position at the detection position is detected with little vibration, Detection accuracy can be increased. In addition, the vibration of the portion other than the front end of the sheet is also suppressed, and the sheet can be prevented from skewing (claim 1).

  According to the second aspect of the present invention, in addition to the effect of the first aspect, the sheet passing through each bent portion of the first and second guide means in the sheet conveying direction is opposed to the opposite wall facing each bent portion. Since gaps can be held between them and they are not pinched, even if the sheet is thick, firm, strong in thickness, and large in deviation, it will increase the transport resistance and generate noise. Can be suppressed.

  According to the invention described in claim 3, there is no member that newly adds a conveyance resistance to the sheet until the sheet passing through the sheet conveyance region reaches the registration roller pair after the leading edge of the sheet is detected at the detection position. Since the increase and fluctuation of the sheet conveyance resistance are suppressed, it is possible to prevent variations in the time to reach the registration roller pair, delay of sheet biting due to insufficient pressure on the registration roller nip, and no sheet biting. It is possible to prevent problems such as the occurrence of a uniform state, the leading edge margin of the sheet being shortened, and the occurrence of skew.

  According to the fourth aspect of the present invention, the friction on the guide plate surface is reduced by the friction reducing member even when the sheet is thick, firm, strong in thickness, and large in deviation. As a result, a further effect of reducing the sheet conveyance resistance can be obtained as compared with the configuration of the first aspect.

  According to the fifth aspect of the present invention, when the sheet is deformed into a curved shape with the bent portion of the first guide means as the starting point, if the width of the protruding portion in the conveying direction is narrow, the sheet is likely to be locally bent. On the other hand, when a rotating member is used, local folding can be prevented by aligning the sheet along the arc-shaped contour, and stable conveyance can be obtained. It is possible to prevent creases, creases, increased conveyance resistance, and sudden fluctuations in conveyance resistance.

  According to the invention described in claim 6, in particular, since the rotating member has a driving force, it is possible to compensate for a reduction in conveying force due to a friction load even if the sheet is thick and strong. Thus, stable transportability can be obtained.

  According to the seventh aspect of the present invention, the rib formed in the bent portion reduces the contact area with the sheet, thereby reducing the frictional resistance and obtaining a stable transportability.

  According to the eighth aspect of the present invention, when an excessive pushing force is applied to the gap between the first guide means and the second guide means, the second guide means rotates to reduce the conveyance resistance applied to the sheet. , Stable transportability can be obtained. In particular, even in the case of a bag-shaped sheet having a large sheet thickness, strong stiffness, and large conveyance resistance, it is possible to compensate for a decrease in conveyance force due to a friction load, and to obtain a stable conveyance property. Can do.

  According to the ninth aspect of the present invention, when the width of the conveying unit in the direction perpendicular to the sheet conveying direction is wider than the sheet width, the thickness of the sheet is large, the stiffness is strong, and the conveying resistance is increased. However, since a stable conveying force can be given to the sheet, slippage of the conveying roller constituting the conveying means and skewing of the sheet can be reduced. In addition, in the case of a square bottom medicine bag or a horizontal gusset medicine bag, since the gusset part can be pressurized to fold the fold part, the opening of the gusset part during transportation can be reduced and stable transportability can be obtained. .

  According to the tenth aspect of the present invention, the pair of rollers as the conveying means have the same hardness, the region where the sheet is sandwiched between the pair of rollers is a flat surface, and the conveying force is at the portion where the sheet is released from the pair of rollers. Parallel to the conveying direction, no component force of the conveying force is applied in the direction perpendicular to the sheet conveying direction. For this reason, since the vibration of the sheet released from the conveying means is suppressed in the sheet conveying area, the phenomenon that the vibration is transmitted to the leading edge of the sheet and flickers at the leading edge of the sheet can be prevented.

  According to the eleventh aspect of the present invention, the image forming apparatus having the sheet conveying device according to any one of the first to tenth aspects exhibits the effects of the respective inventions.

  According to the twelfth aspect of the present invention, the image reading apparatus having the sheet conveying apparatus according to any one of the first to tenth aspects exhibits the effects of the respective inventions.

  According to a thirteenth aspect of the present invention, the sheet conveying device according to any one of the first to tenth aspects or the image forming apparatus having the image reading device according to the twelfth aspect of the present invention exhibits the effects of the respective inventions.

  According to a fourteenth aspect of the present invention, in the image forming apparatus comprising any one of a copying machine, a facsimile machine, a printer, a printing machine, and an ink jet recording apparatus, or a composite machine in which at least two of them are combined, each of the above inventions The effect of.

1 is a schematic front view illustrating an overall configuration of an image forming apparatus having a sheet conveying apparatus to which an embodiment of the present invention is applied. FIG. 2 is an enlarged function explanatory cross-sectional view of a sheet conveying device employed in the image forming apparatus of FIG. 1. FIG. 2 is a perspective view of a sheet conveying device employed in the image forming apparatus in FIG. 1. FIG. 3 is an enlarged cross-sectional view of a conveyance roller that conveys a sheet to a skew feeding correction unit used in the sheet conveyance device of FIG. FIG. 9 is an enlarged function explanatory cross-sectional view of a first modification of the sheet conveying apparatus that can be used instead of the sheet conveying apparatus of FIG. FIG. 6 is a perspective view of a first modification of the sheet conveying device in FIG. 5. FIG. 10 is a perspective view of a main part of a skew feeding correction unit used in a second modification of the sheet conveying apparatus that can be used instead of the sheet conveying apparatus of FIG. FIG. 10 is a perspective view of a main part of a skew feeding correction unit used in a third modification of the sheet conveying apparatus that can be used instead of the sheet conveying apparatus of FIG. FIG. 9 is an enlarged function explanatory cross-sectional view of a third modification of the sheet conveying apparatus shown in FIG. 8. FIG. 10 is a perspective view of a main part of a skew feeding correction unit used in a modified example 4 of the sheet conveying apparatus that can be employed instead of the sheet conveying apparatus of FIG. 1. FIG. 11 is an enlarged function explanatory cross-sectional view of a fourth modification of the sheet conveying apparatus illustrated in FIG. 10. It is a schematic front view which shows the whole structure of the image forming apparatus which has a sheet conveying apparatus to which other embodiment of this invention is applied. FIG. 13 is an enlarged function explanatory cross-sectional view of Modification 5 of the sheet conveying apparatus shown in FIG. 12. (A) is a three-sided glue bag, (b) is a two-sided glue bag. (A) is a perspective view, (b) is a side view in the A direction, and (c) is a front view. Is a square bottom medicine bag, (a) is a perspective view, (b) is a front view with the bottom folded, (c) is a front view of the bottom.

  Hereinafter, embodiments of the present invention (hereinafter referred to as “embodiments”) including embodiments for carrying out the present invention will be described with reference to the drawings. Constituent elements such as members and components having the same function and shape throughout the embodiment and the modified examples are given the same reference numerals and will not be described after being described once.

(First embodiment)
A sheet conveying apparatus to which a first embodiment of the present invention is applied and an image forming apparatus equipped with the same will be described with reference to FIGS. First, an overall configuration of a full-color printer 100 as an example of an image forming apparatus will be described with reference to FIG.
This full-color printer 100 is used as various sheet-like recording media (hereinafter referred to as “sheets”) according to image information of an input document, in addition to plain paper generally used for copying and the like, an OHP sheet, a card, Image formation can be performed on cardboard such as postcards and bag-like sheets such as envelopes.

  A full-color printer 100 shown in FIG. 1 has an intermediate transfer belt 11 wound around a plurality of rollers disposed substantially at the center of the apparatus main body, and 4 along the lower running side of the intermediate transfer belt 11. Image forming units 10M, 10C, 10Y, and 10Bk (generally referred to as “10”) are arranged.

  Each image forming unit 10 has the same structure, and each includes a photosensitive drum 1 as an image carrier. Around the photosensitive drum 1, a charging unit 101, a developing device 102, a cleaning unit 103, and the like are arranged, respectively, and further as a primary transfer unit inside the intermediate transfer belt 11 at a position facing each photosensitive drum 1. A transfer roller 12 is provided. In the case of this example, the four image forming units 10 are configured in the same structure, but the color of the developer handled by the developing device of each image forming unit is magenta (denoted by symbol M in FIG. 1), cyan. 4 (referred to as “C” in FIG. 1), yellow (referred to as “Y” in FIG. 1), and black (referred to as “BK” in FIG. 1). In the case of this example, the four image forming units 10 are arranged in the order of magenta, cyan, yellow, and black from the left in FIG. Each image forming unit 10 is detachably attached to the apparatus main body as a process cartridge.

  An optical writing device 14 is provided below the image forming unit 10. Although not shown, the optical writing device 14 has a polygon mirror, a group of mirrors, etc., and irradiates the surface of the photosensitive drum 1 of each color image forming unit with light-modulated laser light. The optical writing device may be provided individually for each image forming unit 10, but using a common optical writing device is advantageous in terms of cost. In this example, the intermediate transfer belt 11 and the optical writing device 14 are also unitized and configured to be detachable from the apparatus main body 50.

  A sheet feeding device 15 is provided at the lower portion of the apparatus so that the sheet size can be selected alternatively automatically or according to a user's manual setting according to the size of the document to be read. The sheet feeding device 15 includes two-stage sheet feeding cassettes 15a and 15b as sheet storage means. Each of the sheet cassettes 15a and 15b is loaded with a large number of various sheets S including bag-shaped sheets S1 (see FIG. 16) having different sizes and vertical and horizontal orientations as different paper types.・ It is stored.

Paper feeding means 16a and 16b are provided corresponding to the paper feeding cassettes 15a and 15b. Each of the paper feeding units 16a and 16b includes a calling roller r1, a supply roller r2, and a separation roller r3.
In order to convey the sheet fed by the sheet feeding means 16a and 16b, a pair of conveying rollers 17a and 17b (collectively referred to as reference numeral 17) as conveying means are provided at two vertical positions on the conveying path. Is provided.

In order to convey a sheet such as transfer paper fed by the sheet feeding means 16a and 16b to the downstream image forming unit (secondary transfer unit K side described later) via the sheet conveyance path R1, the main part of the present invention. Is provided.
Next, a characteristic configuration of the sheet conveying apparatus A to which the present invention is applied will be described.

  As shown in FIGS. 2 and 3, the sheet conveying apparatus A transfers the sheet S drawn from the sheet feeding apparatus 15 shown in FIG. 1 to the second transfer section D, which is an image forming section, along the sheet conveying path R1. In particular, the sheet is conveyed downstream by two upper and lower conveying roller pairs 17a and 17b, which are conveying means on the upstream side of the sheet conveying path R1, and the sheet is corrected by the skew correcting means A1 on the downstream side. The skew feeding is adjusted, the leading edge of the sheet is detected, and the sheet is conveyed to a pair of registration rollers 18a and 18b (generally referred to as 18).

  As shown in FIG. 1, the paper feeding device 15 is provided below the device main body 50, and is provided so that the paper size can be selected alternatively automatically or according to the user's manual setting according to the size of the document to be read. ing. That is, the sheet feeding device 15 stores and arranges a plurality of sheet feeding cassettes 15a and 15b and manual feed trays 33 as sheet storing means in multiple stages. In each of the paper feed cassettes 15a and 15b, a large number of sheets S having different sizes and different vertical and horizontal orientations with respect to the paper transport direction are stacked and stored.

Two conveying roller pairs 17a and 17b (generally referred to as 17) are provided as conveying devices for conveying the sheet S drawn from the sheet feeding cassettes 15a and 15b by the sheet feeding means 16a and 16b to the downstream side. Is done. The pair of conveying rollers 17a and 17b at the two upper and lower positions have the same configuration and are driven by a driving unit (not shown) to convey the sheet in the sheet conveying path R1 to the downstream side in a nipped state.
As shown in FIG. 3, the pair of conveying rollers 17a and 17b is formed such that the roller length Lr in the direction perpendicular to the sheet conveying direction is wider than the sheet width Ls of the sheet S in the sheet conveying path R1.

  Accordingly, the conveyance roller pair 17a, 17b and the registration roller pair 18 described later are sheets S having a large thickness and strong stiffness, for example, the horizontal gusseted medicine bag Sc and the square bottom medicine bag Sd, and the conveyance resistance is increased. Even in the case, a stable conveying force can be given to the sheet S. Also in this respect, slipping of the conveying roller pair 17a, 17b and skewing of the sheet S can be reduced, and vibration is not generated in the sheet S released from the conveying roller pair 17. Further, since the gussets m and m1 shown in FIGS. 15 and 16 can be pressed to fold the folds, there is an effect of reducing the gusset opening during conveyance.

Further, the conveying roller pair 17 is formed with the same hardness. As a result, as shown in FIG. 4, the pair of rollers 17 that sandwich the sheet S has a flat sandwiching opposing region 17 p that sandwiches the sheet S. For this reason, when the sheet S is released from the conveying roller pair 17, the conveying forces f1 and f1 on both sides of the sheet S are parallel to the conveying direction of the sheet S as indicated by the two-dot chain line, and the sheet conveying direction Thus, the component forces of the conveying forces f1 and f1 are not generated in the vertical direction. For this reason, the vibration at the rear end side of the sheet S is transmitted to the front end of the sheet S when released from the nipping state by the conveying roller pair 17 to reliably prevent the phenomenon that the front end of the sheet fluctuates. .
As shown in FIGS. 1 and 2, the skew feeding correction means A1 includes a first guide plate 80 and a second guide plate 70 which are arranged to face each other via the sheet conveyance path R1, and further, a part of the sheet conveyance path R1 And a sheet conveyance region J for correcting the skew of the sheet reaching between the upper (downstream) conveyance roller pair 17, both guide plates 80 and 70, and the registration roller pair 18.

The first guide plate 80 and the second guide plate 70 are provided with bent portions 81 and 71, respectively, and the protruding directions of the bent portions 81 and 71 are arranged perpendicular to the sheet conveying direction. The first and second guide plates 80 and 70 are formed continuously by bending the plate-like upstream side wall and downstream side wall with the bent portions 81 and 71 interposed therebetween.
Here, the upstream end of the upstream side wall of the first guide plate 80 extends to the vicinity of the upstream one conveying roller 17a. Here, one end of the merging portion guide plate 85 is disposed opposite to a position near the downstream side of the other conveying roller 17b. The merging portion guide plate 85 is bent at an acute angle, and the other end is opposed to the refeed roller 58. Is extended to the vicinity of the driven roller 581 on the lower side. The downstream end of the downstream side wall of the first guide plate 80 extends straight so as to face the registration roller pair 18.

  On the other hand, the upstream side wall of the second guide plate 70 extends straight from the bent portion 71, and the upstream side end extends to the vicinity of the upper driven roller 581 that forms a pair with the refeed roller 58. Further, the end is extended in parallel with the downstream side wall of the first guide plate 80 so as to face the registration roller pair 18.

  As shown in FIG. 2, the central portion of the downstream side wall of the first guide plate 80 in the intermediate direction in the conveying direction and the central position of the bent portion 71 of the second guide plate 70 are opposed to each other. 82 and 72 are formed, and a detection region of the registration sensor 36 disposed on the back side of the downstream side wall of the first guide plate 80 is formed. Here, the registration sensor 36 is supported on the apparatus main body 50 side, and is configured to detect the leading edge of the sheet S through the openings 82 and 72 of the second guide plate 40 and the first guide plate 30.

  Here, the one side wall of the merging portion guide plate 85 and the upstream side wall of the first guide plate 80 are part of the sheet conveyance region J and form an upstream region of the merging point cp (see FIG. 2) of the sheet conveyance path R1. The other side wall of the merging portion guide plate 85 and the upstream side wall of the second guide plate 70 are below the manual feed path R2 (also serving as the discharge path of the refeed path 62) extending from the manual feed tray 33 and the paper feed means 34. Form a basin. As a result, the first and second guide plates 80 and 70 and the junction guide plate 85 form a junction point cp where both paths merge.

  The bent portion 81 of the first guide plate 80 is disposed opposite to the upstream side wall of the second guide plate 70 via the sheet conveyance region J, and has a gap L1 having a width sufficiently larger than sheets of various thicknesses passing therethrough. It is formed to hold. Further, the bent portion 71 of the second guide plate 70 is disposed opposite to the downstream side wall of the first guide plate 80 via the sheet conveying region J, and the interval L2 having a width sufficiently larger than the sheets of various thicknesses passing therethrough. It is formed to hold.

  Here, the gaps L1 and L2, which are the gaps in the sheet thickness direction, are irregularly distributed in bag-shaped sheets, for example, deviations in thickness and crushing of the bent portion, and deviations in stiffness (bending rigidity) are extremely large. When the square bottom medicine bag Sd (see FIG. 16) is moved in the sheet conveying region J and is in contact with the bent portions 81 and 71 and slightly curved, the interval can be moved without receiving excessive sliding resistance. Set to For example, as shown in FIG. 2, one side of the square bottom medicine bag Sd sandwiched between the conveyance roller pairs 17 a and 17 b and moving in the sheet conveyance region J abuts against the bent portion 81 of the first guide plate 80, and the other side Is conveyed downstream while abutting against the bent portion 71 of the second guide plate 70. At this time, the square bottom medicine bag Sd sequentially contacts the bent portions 81 and 71 of the first guide plate 80 and the second guide plate 70, and the distal end side is slightly curved in the front and back directions. The intervals L1 and L2 are set such that the corner bottom portion 51 and the folded portion 53 can move without receiving excessive sliding resistance.

  As shown in FIG. 2, a PET film 85 is attached to the upstream side wall portion from the bent portion 81 of the first guide plate 80, and a PET film 73 is attached to the upstream side wall portion from the bent portion 71 of the second guide plate 70, respectively. A transfer surface is formed. As a result, when the leading edge of the sheet S that has reached the upstream side of the sheet conveyance region J abuts on the PET film 85 on the upstream side of the bent portion 81, it can smoothly move to the downstream side, and further move to the downstream side. When it comes into contact with the PET film 73 on the upstream side of the bent portion 71, it can move smoothly to the downstream side. Note that a method of reducing friction by forming a thin film such as a Teflon (registered trademark) coating on the conveyance surface of the first guide plate 80 and the second guide plate 70 facing the sheet conveyance region J may be employed.

Next, an image forming operation in the full-color printer 100 employed in the present embodiment configured as described above will be briefly described.
The photosensitive drum 1 of the image forming unit 10 described above is rotationally driven in the clockwise direction in the drawing by a driving unit (not shown), and the surface of the photosensitive drum 1 is uniformly charged to a predetermined polarity by the charging unit 101. The charged photoconductor surface is irradiated with laser light from the optical writing device 14, whereby an electrostatic latent image is formed on the photoconductor drum 1 surface. At this time, the image information exposed on each photosensitive drum 1 is single-color image information obtained by separating a desired full-color image into magenta, cyan, yellow, and black color information. Each color toner is applied from the developing device 102 to the electrostatic latent image formed in this manner, and visualized as a toner image.

  Further, the intermediate transfer belt 11 is driven to run counterclockwise in the drawing as indicated by an arrow, and each color toner image is sequentially transferred from the photosensitive drum 1 to the intermediate transfer belt 12 by the action of the primary transfer roller 12 in each image forming unit 10. Overprinted. In this way, the intermediate transfer belt 11 carries a full-color toner image on the surface thereof.

  Note that any one of the image forming units 10 can be used to form a single-color image or a two-color or three-color image. In the case of monochrome printing, image formation is performed using the rightmost Bk unit in FIG. 1 among the four image forming units. Residual toner adhering to the surface of the photosensitive drum after the toner image is transferred is removed from the surface of the photosensitive drum by the cleaning device, and then the surface is subjected to the action of a static eliminator (not shown) so that the surface potential is initially set. To prepare for the next image formation.

On the other hand, various sheets S including bag-shaped sheets are selectively fed from the paper feed cassettes 15a and 15b or the manual feed tray 33, and two upper and lower conveying roller pairs 17, skew correction means A1 on the downstream side thereof, registration rollers The sheet passes through a sheet conveying area J in the sheet conveying apparatus A provided with the pair 18.
The behavior in the sheet conveying apparatus A will be described later.
The sheet S, which has been skew-adjusted in the sheet conveying apparatus A and has been detected at the leading edge, is sent out toward the secondary transfer position by timing with the toner image carried on the intermediate transfer belt 11 by the registration roller pair 18.

  In the full-color printer 100 shown in FIG. 1, a transfer voltage having a polarity opposite to the toner charging polarity of the toner image on the surface of the intermediate transfer belt is applied to the transfer roller 19. Is transcribed. When the sheet S to which the toner image has been transferred passes through the fixing device 20, the toner image is fused and fixed to the paper by heat and pressure. The fixed sheet is discharged by a paper discharge roller 29 to a paper discharge unit 30 formed on the upper surface of the apparatus main body 1.

  When printing on both sides of the sheet S, the sheet S on which the toner image is fixed on one side is caused to enter the switchback conveyance path 61 by appropriately switching the first to third switching claws 21 to 23. At this time, the first and second reversing roller pairs 31 and 32 are rotated in the forward direction (clockwise in FIG. 1). When the trailing edge of the sheet S entering the switchback conveyance path 61 is detected by the sheet sensor 40, the first and second reversing roller pairs 31 and 32 are rotated in the reverse direction (counterclockwise in FIG. 1), and the sheet S is rotated. Invert. At this time, the sheet S reversed by switching the position of the third switching claw 23 is fed into the refeed path 62.

  The sheet refeed path 62 joins the manual sheet feed path R2 from the manual feed tray 33 at the lower end of the sheet refeed path 62, and further, the sheet cassette 15a is located on the back side of the sheet refeed roller 58 that constitutes the conveying means on the sheet refeed path 62 side. , 15b and the sheet conveyance path R1. The sheet S is conveyed in the refeed path 62 by the pair of conveying rollers 26 and 27, and further, the sheet S whose skew is adjusted in the sheet conveying apparatus A by the refeed roller 58 and detected at the leading edge is transferred to the registration roller pair 18. Sent. By passing the sheet S reversed in the switchback conveyance path R161 through the refeed path 62, the front and back of the sheet S are reversed, and the toner image is transferred from the intermediate transfer belt 11 to the back of the sheet, and the back image is transferred. By fixing with the fixing device 20, the sheet S carrying the images on both the front and back sides is discharged to the discharge tray 30 or an optional tray (not shown), thereby completing double-sided printing.

Next, the operation of the sheet conveying apparatus A to which the present invention is applied will be described.
The sheet S fed from the sheet feeding device 15 reaches the sheet conveyance region J in the sheet conveyance device A. Here, the sheet S is sandwiched between the conveyance roller pairs 17a and 17b, and is conveyed from the lower side of FIG.
At this time, as shown in FIGS. 2 and 3, the sheet S moving in the sheet conveyance region J passes through the bent portion 81 with its leading end abutting on the upstream side wall surface of the first guide plate 80, The one surface is slidably contacted with the bent portion 81. At that time, the sheet S has a curved shape with the bent portion 81 of the first guide plate as a bending start point. Next, the leading edge of the sheet S hits the upstream side wall surface of the downstream second guide plate 70, changes the traveling direction along the second guide plate 70, reaches the bent portion 71 while being slightly curved and displaced, and is in a sliding contact state. It passes while holding, and the other surface is in sliding contact with the bent portion 71. The leading edge of the sheet S that has passed through the bent portion 71 passes the detection range upstream boundary 371 of the registration sensor 36, and the registration sensor 36 detects the leading edge of the sheet S. In this case, the registration sensor 36 has a detection range with the optical axis 370 as the center, and the detection accuracy can be improved by suppressing the vertical fluctuation of the leading end position of the sheet S at the detection range upstream boundary 371.

Further, the leading edge of the sheet S advances downstream of the bent portion 71 of the second guide plate 70.
In this case, as shown in FIG. 2, the PET film 85 on the upstream side wall portion of the first guide plate 80 and the PET film 73 on the upstream side wall portion of the second guide plate 70 function, and like the square bottom medicine bag Sd, Even in the case of the sheet S, which is thick, strong, has a large thickness deviation, and a large deviation, it is possible to suppress the fluttering of the sheet tip between the guide plates 80, 70, and there is no film 85, 73. Compared to the case, the effect of reducing the sheet conveyance resistance can be obtained more reliably.

  Further, the sheet S conveyed in the sheet conveying area J is supported by three points while being sandwiched between the pair of conveying rollers 17a and 17b and at the same time the two surfaces are in contact with the two points of the bent portions 81 and 71 and slightly curved. The At this time, when the sheet S facing the bent portion 81 is a square bottom medicine bag Sd, the corner bottom portion 51 and the folded portion 53 at the tip thereof approach the outside in the bending direction, that is, the upstream side wall surface of the second guide plate 80. The distance L1 between the bent portion 81 and the upstream side wall surface of the second guide plate 70 is sufficiently larger than the thickness of the tip including the corner bottom portion 51 and the folded portion 53 of the corner bottom medicine bag Sd. Since it is not pinched by the bending part 81, the displacement of the square bottom part 51 of the square bottom medicine bag Sd sliding while curving the upstream side wall surface of the 2nd guide plate 70 somewhat can be facilitated, and sliding resistance here Can be reliably reduced.

  Similarly, the bent portion 71 of the second guide plate 70 is disposed opposite to the downstream side wall of the first guide plate 80 via the sheet conveyance region J, and the bent portion 71 of the distal end portion including the corner bottom portion 51 of the corner bottom medicine bag Sd passing therebetween is provided. Since the distance L2 having a width sufficiently larger than the thickness is maintained, a slight bending displacement can be allowed, and the sliding resistance can be surely reduced. In other words, the square bottom medicine bag Sd passing through the bent portions 81 and 71 of the first and second guide plates 80 and 70 in the sheet conveying direction holds a gap between the opposing walls facing the bent portions 81 and 71. Because it is not pinched, even if it is a square bottom medicine bag Sd with a thick sheet, strong stiffness, large thickness deviation, and large stiffness deviation, it suppresses an increase in received conveyance resistance and noise generation Moreover, the occurrence of blurring can be regulated.

  It is assumed that the sheet S2 (see FIG. 2) having a small sheet thickness is conveyed as the sheet S to the sheet conveying region J, not the square bottom medicine bag Sd. Even in this case, the sheet S2 is sandwiched between the pair of conveying rollers 17a and 17b, and at the same time, the both surfaces are in contact with each other while being bent at two points of the bent portions 81 and 71, and are supported at three points. For this reason, even if it is thin paper S2, the stiffness (bending rigidity) of the paper works, and it does not cause blur due to contact with the upstream side wall surfaces of the first and second guide plates 80 and 70, and is excessively conveyed. Can move without resistance.

  Next, the sheet S reaches the registration sensor 36 positioned immediately after the bent portion 71 of the second guide plate 70. In this case, the sheet S is sandwiched between the pair of conveying rollers 17a and 17b, and at the same time, the both surfaces are curved at the two points of the bent portions 81 and 71, and are in contact with each other and are not shaken in a state where the whole is supported at three points. It is supported. At this time, since the leading edge of the sheet S is not shaken, the leading edge of the sheet S can be stably moved and detected accurately when the sheet S passes the detection range upstream boundary 371 of the registration sensor 36.

  Next, the sheet S moves toward the registration roller pair 18 after the leading edge of the sheet is detected at the detection position. Here, a space L2 between the bent portion 71 of the second guide plate 70 and the downstream side wall of the first guide plate 80 is maintained as it is between the downstream side wall surfaces of the first second guide plates 80 and 70. ing. For this reason, the sheet S is sandwiched between the conveying roller pairs 17a and 17b and receives a conveying force, and both surfaces of the sheet S are conveyed while being slightly curved at two points of the bent portions 81 and 71. In this case, the sheet S supported at three points is conveyed without newly receiving conveyance resistance while the front end side thereof is sufficiently spaced from the first and second guide plates 80 and 70, and the conveyance resistance of the sheet S is increased. Thus, fluctuations at the time of contact of the registration roller pair with the nip portion can be prevented.

  Next, the leading edge of the sheet S further advances in the sheet conveyance region J (space) sandwiched between the first guide plate and the second guide plate, and abuts against the nip portion of the registration roller pair 18. Here, the registration roller pair 18 is controlled to start rotating after a lapse of a predetermined time after the registration sensor 36 detects the leading edge of the sheet S, and the registration roller pair 18 starts rotating after the sheet S hits. Deflection for the time until it occurs. The skew of the leading edge of the sheet S is corrected by this bending, and the sheet S passes through the registration roller pair 18 and is sent to the downstream unit.

  As described above, there is no deviation in the amount of displacement in which the sheet S is curved by receiving the conveying force of the conveying roller pairs 17a and 17b for a predetermined time after the leading end side of the sheet S contacts the registration roller pair 18. The line correction displacement amount is an appropriate amount. As a result, there is no delay in the sheet biting or non-uniform state of the sheet biting due to insufficient pressure applied to the nip portion of the registration roller pair, and the leading edge margin of the sheet is shortened or skewing occurs. This problem is prevented in advance.

Next, <Modification 1> will be described with reference to FIGS.
Modification 1 is different from the sheet conveying apparatus A and the full-color printer 100 shown in FIGS. 1 to 3 only in that a sheet conveying apparatus B instead of the sheet conveying apparatus A is used. The sheet conveying apparatus B is different from the sheet conveying apparatus A only in the configuration of the second guide plate 70B. This modification 1 is the same as the sheet conveying apparatus A and the full-color printer 100 shown in FIGS.

  This sheet conveying apparatus B employs a first guide plate 80 having a bent portion 81 and a second guide plate 70B having a bent portion 71 disposed opposite thereto as the skew feeding correcting means B1.

  The second guide plate 70B is employed in place of the second guide plate 70 shown in FIGS. 1 to 3, and a curved cross-sectional portion 701 that is curved outside the sheet conveying region J is formed in a downstream side wall portion directly below the bent portion 71. The The curved cross-section 701 makes it possible to form the bending angle α of the bending portion 71 relatively large regardless of the subsequent inclined state of the downstream side wall portion. By forming the bending angle α to be large, the reduction of the sliding resistance of the sheet S can be more effectively reduced.

Next, <Modification 2> will be described with reference to FIG.
8 is different from the sheet conveying apparatus A and the full-color printer 100 shown in FIGS. 1 to 3 in the configuration of the plate-like portion in FIG. 8 in place of the second guide plate 70 in the sheet conveying apparatus A. The overall configuration of the sheet conveying apparatus C is the same as that of the sheet conveying apparatus A in FIG. 2, and the entire structure here is substituted for the sheet conveying apparatus A in FIGS. 1 to 3. The illustration of the configuration is omitted. The second modification is the same as the sheet conveying apparatus A and the full-color printer 100 shown in FIGS. 1 to 3 except for the differences.

The sheet conveying apparatus C (see the sheet conveying apparatus A in FIG. 2) includes a first guide plate 80 having a bent portion 81 as a skew feeding correction means C1 and a second guide plate 70C having a bent portion 71 disposed opposite thereto. And adopt. Here, the second guide plate 70 </ b> C has a plurality of elongated hole-like ribs 702 continuously formed on the upstream side wall, the bent portion 71, and the downstream side wall.
Since the plurality of ribs 702 are continuously formed with a constant width along the sheet conveying direction in parallel with each other, the plurality of ribs 702 can reduce the contact area with the sheet S and reduce the sliding resistance. It is also effective to reduce the contact area by providing the first guide plate 80 with ribs 702 similar to the second guide plate 70C.

According to the second modification, in particular, the sliding contact area when the sheet S is conveyed in the sheet conveying direction can be reduced, the sliding resistance can be reduced, and the effect of restricting the deviation in the direction orthogonal to the conveying direction can also be obtained. , Stable transportability can be obtained.
Note that a projecting bead (not shown) may be provided instead of the elongated hole-shaped rib 702. Furthermore, although the rib 702 parallel to the sheet conveyance direction is arranged in the modification 2 of FIG. 7, it is formed in a skewed shape (reverse C shape) opened in the sheet conveyance direction with the conveyance center as the target axis. It may be possible to reduce sliding resistance and ensure straightness.

Next, <Modification 3> will be described with reference to FIGS.
Modification 3 employs the first guide plate 80d of FIG. 8 in place of the first guide plate 80 in the sheet transport apparatus A, as compared with the sheet transport apparatus A and the full-color printer 100 shown in FIGS. The overall configuration of the sheet conveying apparatus D is the same as that of the sheet conveying apparatus A in FIG. 2, and the illustration of the entire configuration is omitted here. The third modification is the same as the sheet conveying apparatus A and the full-color printer 100 shown in FIGS. 1 to 3 except for the differences.

  Here, the sheet conveying apparatus D employs a first guide plate 80d having a bent portion 81d and a second guide plate 70 disposed opposite thereto as the skew feeding correction means D1. Here, a guide roller 811 which is a rotating member is provided in the bent portion 81d of the first guide plate 80d. The first guide plate 80d has end bent portions 81d-1 having a predetermined width at both ends in a direction orthogonal to the sheet conveying direction, and a long hole-shaped opening 812 having a predetermined width is formed in the central region. . A guide roller 811 is rotatably fitted over almost the entire area of the opening 812. The guide roller 811 protrudes at the left and right ends of the central axis 813 of the guide roller 811 so that a part of the outer peripheral surface of the roller protrudes from the end bent portion 81d-1 to the sheet conveyance region J, and the apparatus main body 50 (FIG. 1). It is pivoted on the reference side.

  The guide roller 811 that is a means for conveying the sheet is formed so as to pass through the sheet conveyance region J (space) and to be wider than the width in the sheet conveyance direction of the sheet S that is skew-corrected. As a result, when the sheet S is thick and strong, and the sheet S is deformed into a curved shape starting from the bent portion 81, if the width of the bent portion 81 in the conveying direction is narrow, the sheet S is locally bent. This will cause folds, resulting in folds, creases, increased conveyance resistance, and sudden fluctuations in conveyance resistance, but here it is deformed into a curved shape, so the sheet follows the circular outline. By doing so, local folding can be prevented and stable conveyance can be obtained.

  Next, a motor 815 that is a rotating member driving unit is connected to one end of the central shaft 813 of the guide roller 811 via a gear train 814. The motor 815 is driven and controlled during sheet conveyance, and the outer peripheral surface of the opening 812 of the guide roller 811 protruding from the opening 812 via the gear train 814 can be rotationally driven in the sheet conveyance direction by the driving force.

In some cases, the drive transmission of the guide roller 811 is performed by a method in which the motor shaft is integrally connected to the central shaft 813 of the guide roller 811 and the motor 815 is directly driven, or a method in which the drive is transmitted via a belt drive transmission means. Can also be adopted. Further, a method of distributing the driving of the conveying roller pairs 17a and 17b by a gear and belt drive transmission means without using a dedicated motor can be employed.
The guide roller 811 shown in FIG. 9 has a shape that is continuous in the direction perpendicular to the sheet conveying direction, but can also be divided into a plurality of rollers. In FIG. 9, the guide roller 811 is provided only on the first guide plate 80, but may be provided only on the second guide plate 70 or on both the first guide 80 plate and the second guide plate 70.

  Assume that the drive of the guide roller 811 shown in FIG. 9 is controlled. At that time, the sheet S is curved along the contour of the guide roller 811 protruding from the first guide plate 80, and at the same time, the sheet S is rotationally driven as the sheet S is conveyed. In this case, even if the sheet S moving through the sheet conveyance region J is thick and firm, for example, a sheet such as a square bottom medicine bag Sd, it is possible to compensate for a decrease in conveyance force due to a friction load. , Stable transportability can be obtained. In some cases, the first guide plate may be configured such that the motor 815 that is a rotating member driving unit is excluded from the guide roller 811 and the guide roller 811 is rotated only by the frictional force with the sheet S that moves in the sheet conveyance region J. The configuration may be simplified to reduce the sliding resistance of the 80d bent portion 81d.

Next, <Modification 4> will be described with reference to FIGS.
Modification 4 employs the second guide plate 70e of FIG. 10 instead of the second guide plate 70 of the sheet transport device A, as compared with the sheet transport device A and the full-color printer 100 shown in FIGS. The overall configuration of the sheet conveying apparatus E is the same as that of the sheet conveying apparatus A in FIG. 2, and the illustration of the entire configuration is omitted here.
The fourth modification is the same as the sheet conveying apparatus A and the full-color printer 100 shown in FIGS.

The sheet conveying apparatus E employs a first guide plate 80 having a bent portion 81 and a second guide plate 70E having a bent portion 71 disposed opposite thereto as the skew feeding correcting means E1.
The first guide plate 80 is fixed to the apparatus main body 50 side, and the second guide plate 70E is pivotally supported to the apparatus main body 50 side. Extending pieces 76 bend and extend vertically on both side ends near the upstream end of the upstream side wall of the second guide plate 70E, and pivots 77 extending in the direction of the rotation center line La project therefrom. . These pivots 77 are pivotally supported by a support bracket (not shown) on the apparatus main body 50 side.

  Here, the second guide plate 70E can be rotationally displaced about the rotation center line La via both pivot shafts 77. Note that the second guide plate 70E is returned and held by the return spring 79 to the position where the above-described distance L2 is held with respect to the downstream side wall portion of the first guide plate 80 in a steady state, and excessive force in the pushing-open direction is applied to the sheet S. For example, when the square bottom medicine bag Sd having a relatively large thickness passes, the downstream side wall of the second guide plate 70E is displaced from the downstream side wall of the first guide plate 80 against the spring force. it can.

  Further, the end portions of both end arm portions 781 of the U-shaped bracket 78 are fixed to both side edges of the downstream side wall portion of the second guide plate 70E. Further, the central portion 782 of the U-shaped bracket 78 is rotatably disposed without interfering with the back side of the downstream side wall portion of the second guide plate 70E. Here, the central area of the central portion 782 forms a mounting portion for the detection means, and the registration sensor 36 is attached thereto. The registration sensor 36 accurately and stably detects the leading edge of the sheet S passing through the detection range upstream boundary 371 of the registration sensor 36 formed on each downstream side wall portion of the first second guide plates 80 and 70E.

  Assume that the sheet S is transported to the sheet transport region J of the sheet transport apparatus E shown in FIGS. In this case, when the sheet S is thick and firm, for example, in the case of the square bottom medicine bag Sd, the distance between the steady state L1 and L2 between the first guide plate 80 and the second guide plate 70E is excessively widened. Power may be added. At this time, when the second guide plate 70E rotates around the rotation center line La, the normal intervals L1 and L2 are expanded against the spring force, and the sheet S is stabilized while reducing the conveyance resistance applied to the sheet S. Can be transported reliably. At this time, the registration sensor 36 integrated with the second guide plate 70 </ b> E is integrally displaced via the U-shaped bracket 78, and there is no change in the state facing the opening 72. On the other hand, the opening 82 is formed in advance so as not to interfere in the entire fluctuation region of the optical axis of the registration sensor 36 and the detection range upstream boundary 371. For this reason, even if the registration sensor 36 is displaced and displaced via the second guide plate 70E due to the variation in the thickness of the sheet S, the displacement of the detection area of the sensor can be restricted and the openings 82 and 72 may be interfered. The registration sensor 36 can accurately detect the leading edge of the sheet S.

(Second Embodiment)
The second embodiment will be described with reference to FIGS. The second embodiment is different from the sheet conveying apparatus A and the full color printer 100 shown in FIGS. 1 to 3 only in that a copying machine 200 that replaces the full color printer 100 is used. The sheet conveying apparatus F of the copying machine 200 is not substantially different from the sheet conveying apparatus A shown in FIGS. 1 to 3 and has the same configuration, so the description of the sheet conveying apparatus F is simplified. The same code | symbol is attached | subjected to the same member.

  The copying machine 200 mounts the image forming apparatus main body 202 that performs a predetermined image forming process based on the read document image, and supplies the sheet S to the apparatus main body 202 one by one. A sheet feeding device 215 and a document reading device 204 mounted on the image forming apparatus main body 202 for reading a document image and sending the document image information to the image forming apparatus main body 202 are provided.

  A paper discharge tray 209 is installed on the upper portion of the image forming apparatus main body 202, and a conveyance path R1 for moving the sheet S from the paper supply device 215 to the paper discharge tray 209 is formed. Most of the conveyance path R1 extends from the sheet feeding device 215 to the upper part of the image forming apparatus main body 202, and extends in a substantially vertical upward direction, that is, a substantially vertical upward direction with respect to a substantially horizontal line. Are provided with a plurality of sheet conveying means (hereinafter referred to as “sheet conveying means”) configured by conveying roller pairs, roller pairs, and the like with a predetermined interval corresponding to the minimum size sheet S. Further, the sheet feeding device 215 includes a sheet feeding device 205 that feeds and conveys the sheet S accommodated in each stage of the sheet feeding device 215 to the conveyance path R1, and a sheet conveying device F that continues downstream from the sheet feeding device 205. Is installed.

  In the image forming apparatus main body 202, a photoreceptor unit 210 and a fixing device 211 as an image forming unit for forming an image are sequentially arranged from the upstream side to the downstream side of the conveyance path R1. After the photosensitive unit 210 transfers the generated toner image to the sheet S conveyed from the upstream side to the downstream side on the conveyance path R1, the fixing device 211 transfers the transferred toner image. The sheet S fixed on the sheet S and having the toner image fixed thereon is discharged to a discharge tray 209 disposed at the end of the transport path R1.

  The photoconductor unit 210 has a single drum-like photoconductor 210A as an image carrier, and is rotatably supported on a side plate (not shown) in the image forming apparatus main body 202 around a rotation axis. The photosensitive member 210A is stabilized in the rotational direction indicated by an arrow in the figure when a rotational driving force is transmitted from a driving source such as a motor provided on either the photosensitive unit 210 side or the image forming apparatus main body 202 side. It is driven to rotate at a constant speed.

  Around the photoconductor 210A, a developing device 212, a transfer device 213, a photoconductor cleaning device 218, a charge eliminating device, and a charging device 214 are arranged in the rotation direction indicated by the arrows in the drawing. Within the range of one rotation in the counterclockwise rotation direction, the development position, transfer position, cleaning position, charge removal position, and charging position are sequentially set from upstream to downstream by each of these devices 212 to 214. Is set.

  Further, a latent image forming position is set between the charging position and the developing position, and exposure is performed to write an invisible latent image corresponding to the image information by irradiating the latent image forming position with a predetermined laser beam. The device 247 is disposed obliquely below and slightly away from the photoreceptor unit 210. The photosensitive member 210A is rotationally driven in a predetermined counterclockwise direction, and each of the devices 212 to 214 and the exposure device 247 perform a cooperative operation in cooperation with each other in synchronization with the rotation of the photosensitive member 210A. Thus, a series of image forming processes are executed.

  That is, the developing device 212 has an appropriate well-known configuration such as a developing roller that generates a toner brush in which toner particles are erected radially from the surface thereof, and is generated at a predetermined location on the surface of the photoreceptor 210A. The toner particles at the tip of the toner brush are attached to the latent image that moves around the circumference and passes through the developing position with the rotation of 210A, and the invisible latent image is visualized as a monochrome toner image.

  The transfer device 213 includes two support rollers 215 and 216 that are opposed to each other with a predetermined distance in the substantially vertical direction, and a transfer belt 217 that is an endless belt stretched between the support rollers 215 and 216. Then, the toner image on the outer peripheral surface of the photoreceptor 210A is transferred to the sheet S, and the sheet S on which the unfixed toner image is transferred is conveyed to the downstream side of the conveying path R1. That is, the lower support roller 216 has a portion around which the transfer belt 217 is wound pressed against an approximately right lower portion of the photosensitive member 210A, and the transfer belt 217 is transferred to a portion where the surface of the photosensitive member 210A and the transfer belt 217 are in contact with each other. A position K1 is set. Further, the upper support roller 215 is disposed in front of the introduction port of the fixing device 211.

  The photoconductor cleaning device 218 is a blade material (not shown) configured such that the blade edge at the tip thereof is in contact with the cleaning position on the photoconductor 210A with a predetermined pressure, or the photoconductor is in contact with the cleaning position. It has either or both of the configurations of a rotating brush that rotates following the rotation of 210A, and removes toner, foreign matter, and the like remaining on the surface of the photoreceptor 210A after transfer.

The static eliminator is mainly composed of a lamp capable of emitting light of a predetermined intensity, and a charge removal state is applied to the surface of the photoreceptor 210A passing through the charge removal position by irradiating the charge removal position from the lamp to the charge removal position. Is released, and the surface potential of the photoreceptor 210A after passing through the transfer position is returned to the initial state.
Note that reference numeral 220 in the figure denotes a toner storage container including a toner bottle that stores new and new toner, and a toner transport path (not shown) is formed from the toner storage container 220 to the developing device 212. When the developing device 212 consumes its own toner for development and becomes insufficient, new toner is replenished from the toner storage container 220 to the developing device 212.

  Below the image forming apparatus main body 202, a sheet feeding device 215 that can select a sheet size automatically or according to a user's manual setting according to the size of a document to be read is provided. The sheet feeding device 215 stores and arranges a plurality of sheet feeding trays 215a and 215b in multiple stages, and each sheet feeding tray 215a and 215b has different vertical and horizontal sizes with respect to various sizes and sheet conveying directions. A large number of sheets S oriented in the direction are stacked and stored.

  The document reading device 204 has a reading device main body 204A that forms the framework, and a contact glass 257 is disposed on the upper surface of the reading device main body 204A over a predetermined range. In the reading apparatus main body 204A, reading means for optically reading a document image with a predetermined range on the surface of the contact glass 257 as a scanning target is accommodated. The reading means includes at least the first traveling body 253, the first traveling body 253, and the like. 2 is mainly composed of a traveling body 254, an imaging lens 255, and a reading sensor 256 including, for example, a CCD.

  Further, in the document reading device 204, a document pressing plate 258 configured to be openable and closable between a closed position that covers the contact glass 257 and an opened open position is provided on the upper surface of the reading device main body 4A. That is, the document pressing plate 258 is formed to have a larger vertical and horizontal dimension than the contact glass 57, and one end of the original pressing plate 258 is supported on the upper surface of the reading apparatus main body 204A by a hinge (not shown) so as to be opened and closed.

  Based on the above configuration, the operation of the copying machine 200 will be described. First, when copying a document with the copying machine 200, the user manually opens the document pressing plate 258 of the document reading device 204 from the closed position to the open position, and places and sets the document on the contact glass 257. The document pressing plate 258 is manually operated in the closing direction, and the document set on the contact glass 257 is pressed from above by the document pressing plate 258. By this operation, the original is brought into close contact with the contact glass 257 and spread in a flat shape so that the original surface can be read accurately, and the original is fixed on the glass 257.

  When the user depresses / turns on a start switch provided on an operation screen (not shown) provided in advance in the copying machine 200, the reading operation of the document reading device 204 is started immediately, and a drive mechanism (not shown) The first traveling body 253 and the second traveling body 254 travel. Then, the light from the light source of the first traveling body 253 is irradiated toward the document, the reflected light from the document surface is directed to the second traveling body 254, and the reflected light is reflected by the mirror of the second traveling body 254. Then, the image is input to the reading sensor 256 via the imaging lens 255. As a result, the reading sensor 256 photoelectrically converts an image of an original or the like and reads it.

  When a start switch (not shown) is turned on, the photosensitive member 210A of the photosensitive unit 210 starts rotating, and an operation for forming a toner image on the photosensitive member 210A based on the read original image is performed. Be started. That is, as the photoconductor 210A is rotated, predetermined portions on the outer peripheral surface of the photoconductor 210A are sequentially arranged between the charging device 214, the exposure device 247, the developing device 212, the transfer device 213, the photoconductor cleaning device 218, and the charge removal device. After passing through the respective positions set in (1) and (2), the toner is sequentially charged to a predetermined charged state, a latent image is generated, visualized as a toner image, transferred to the sheet S, and the residual toner is removed. Then, the charged state is released and one cycle is completed, and the cycle is maintained for a predetermined period so as to generate a toner image in a predetermined length range of the outer peripheral surface in the rotation direction according to the image size to be formed.

  On the other hand, when a start switch (not shown) is pressed, the sheet feeding device 205 attached to the sheet feeding tray 215a, 215b from the sheet feeding tray 215a, 215b storing the automatically or manually selected sheet S in the sheet feeding device 215. With this operation, one sheet S is conveyed to the conveyance path R1 through a predetermined path. The sheet S is conveyed by a conveying roller or the like so that the conveying path R1 facing the sheet conveying apparatus F in the image forming apparatus main body 202 faces substantially vertically upward, and the leading edge of the sheet S abuts against the registration roller pair 221 and temporarily stops. To do. On the other hand, in the case of manual sheet feeding, the sheet S set on the manual tray 267 is first fed out by the rotation of the sheet feeding roller 267A for the manual tray. The sheets are separated into one sheet by tray separation rollers 267B and 267B, conveyed to the manual sheet feeding path R2, and further conveyed from the manual sheet feeding path R2 to the conveying path R1 on the upstream side of the sheet conveying apparatus F. The leading end abuts against the registration roller pair 221 and temporarily stops.

Then, the registration roller pair 221 starts to rotate at an accurate timing in accordance with the relative movement of the toner image on the photoconductor 210A that is driven to rotate, and sends the temporarily stopped sheet S to the transfer position K1. As a result, a toner image is transferred onto the sheet S by the transfer device 213.
The sheet S to which the unfixed monochrome toner image is transferred in this manner is conveyed to the fixing device 211 by the transfer belt 217 of the transfer device 213 that forms a part of the conveyance path R1, and the fixing device 211 generates a predetermined heat and pressure. Is added to fix the image on the sheet S. The sheet S on which the image has been fixed is guided toward the conveyance path R1 reaching the paper discharge tray 209 by the switching claw 234, and is discharged onto the paper discharge tray 209 by each discharge roller row 235, and onto the paper discharge tray 209. Stacked.

  When the double-sided copy mode is selected by the user's setting input, the sheet S on which the image is fixed on one side is conveyed to the sheet reversing device 242 side by the switching claw 234 and is arranged in the sheet reversing device 242. A plurality of rollers 266 and a guide member (not shown) are moved back and forth on the reverse conveyance path R3 to reverse the vertical direction of the sheet surface, and then the resist is registered from a position positioned in front of the photosensitive unit 210. After returning to the conveyance path R1 via the roller pair 221, the sheet is conveyed on the conveyance path R1 and guided again to the transfer position K1, and after the image is transferred and fixed on the back surface of the sheet S, the discharge rollers 235 to 238 are then transferred. As a result, the paper is finally discharged onto the paper discharge tray 209.

Here, a characteristic configuration of the sheet conveying apparatus F to which the present invention is applied will be described.
As illustrated in FIGS. 12 and 13, the sheet conveying device F has a configuration substantially similar to that of the sheet conveying device A illustrated in FIG. 2, and thus the overlapping portion is simplified.
When a start switch (not shown) is pressed, the operation of the sheet feeding device 205 attached to the sheet feeding tray 215a, 215b from the sheet feeding tray 215a, 215b storing automatically or manually selected sheets S in the sheet feeding device 215 is operated. Thus, one sheet S is conveyed to the conveyance path R1 via a predetermined path. The sheet S is arranged below the apparatus main body 205 by a conveyance roller or the like, and the sheet conveying apparatus F and the paper feeding apparatus 215 in the image forming apparatus main body 202 are arranged automatically or manually by the user according to the size of the document to be read. The paper size can be alternatively selected by setting.

  The sheet conveying device F is a sheet S drawn from the sheet feeding cassettes 215a and 215b of the sheet feeding device 215 by the operation of the sheet feeding device 205, or a sheet S conveyed from the manual sheet feeding path R2 to the upstream conveying path R1. Is conveyed by a pair of conveying rollers 297a and 297b (generally referred to as reference numeral 297), the skew feeding correction means F1 on the downstream side adjusts the skew of the sheet, detects the leading edge of the sheet, and conveys the sheet to the registration roller pair 221. Further, the sheet is fed along the downstream conveyance path R1 to the second transfer section K that is an image forming section.

  As shown in FIG. 13, the skew feeding correction means F1 includes a first guide plate 280 and a second guide plate 270 that are arranged to face each other via a sheet conveyance region J (space) that is a part of the sheet conveyance path R1. Further, a sheet conveyance region that forms part of the sheet conveyance path R1 and corrects the skew of the sheet that has reached between the upper (downstream) conveyance roller pair 297, both guide plates 280 and 270, and the registration roller pair 221. J is provided.

The first guide plate 280 and the second guide plate 270 are provided with bent portions 281 and 271, respectively, and the plate-shaped upstream side wall and the downstream side wall are bent continuously with the bent portions 281 and 271 interposed therebetween. is doing.
Here, the upstream end of the first guide plate 280 extends to the vicinity of one of the conveying rollers 297a. Here, one end of the junction guide plate 286 is disposed opposite to the downstream side of the other transport roller 297b. The other end of the junction guide plate 85 extends to the vicinity of the lower roller of the refeed roller 299. It is installed. The downstream end of the downstream side wall of the first guide plate 280 extends straight so as to face the registration roller pair 221.

On the other hand, the upstream side wall of the second guide plate 270 extends straight from the bent portion 271, the upstream side end extends to the vicinity of the refeed roller 299, and the downstream side end of the downstream side wall faces the registration roller pair 221. It is extended.
Openings 282 and 272 are formed at the center position of the downstream side wall of the first guide plate 280 and the center position of the bent portion 271 of the second guide plate 270 so as to face each other. The detection area of the registration sensor 36 disposed on the back side of the sensor is formed. The registration sensor 36 is supported on the apparatus main body 202 side, and is configured to detect the leading edge of the sheet S through the opening 282 of the first guide plate 280 and the opening 272 of the second guide plate 270.

Here, the one side wall of the junction guide plate 286 and the upstream side wall of the first guide plate 280 form the sheet conveyance path R1, and the other side wall of the junction guide plate 286 and the upstream side wall of the second guide plate 70 are re-connected. A downstream end region of the sheet feed path R3 is formed. As a result, the first and second guide plates 280 and 270 and the junction guide plate 286 form a junction point cp where both paths merge.
An interval L1 between the bent portion 281 of the first guide plate 280 and the upstream side wall of the second guide plate 270 is formed to have a width sufficiently larger than sheets of various thicknesses passing therethrough. Furthermore, the distance L2 between the bent portion 271 of the second guide plate 270 and the downstream side wall of the first guide plate 280 is formed to have a width sufficiently larger than sheets of various thicknesses passing therethrough.

For example, as shown in FIG. 13, the sheet S that is sandwiched between the conveyance roller pairs 217 a and 217 b and is moving in the sheet conveyance region J is sequentially applied to both bent portions 281 and 271 of the first guide plate 280 and the second guide plate 270. Although the front end side is slightly curved in the front and back direction by abutting, the distances L1 and L2 at which the sheet S can move without excessively receiving sliding resistance, for example, the corner bottom portion 51 and the folded portion 53 of the corner bottom medicine bag Sd. Set to
In addition, PET films 85 and 73 are affixed to the upstream side wall part of the first guide plate 280 and the upstream side wall part of the second guide plate 270, respectively, and form a conveyance surface. Thus, when the leading edge of the sheet S comes into contact with the PET films 85 and 73, the sheet S can be smoothly moved to the downstream side.

Next, the operation of the sheet conveying apparatus F that is activated in association with the image forming operation in the copying machine 200 employed in the present embodiment configured as described above will be described with reference to FIGS.
When a start switch (not shown) is pressed, the operation of the sheet feeding device 205 attached to the sheet feeding tray 215a, 215b from the sheet feeding tray 215a, 215b storing automatically or manually selected sheets S in the sheet feeding device 215 is operated. Thus, one sheet S is conveyed to the conveyance path R1 through a predetermined path. The sheet S is transported substantially vertically upward along a transport path R1 facing the sheet transport device F, and the leading edge of the sheet S abuts against the registration roller pair 221 and temporarily stops.

In the sheet conveying apparatus F, the sheet S is sandwiched between the conveying roller pairs 297a and 297b and conveyed through the sheet conveying area J to the downstream side.
At this time, the leading edge of the sheet S moving in the sheet conveyance region J passes through the bent portion 281 of the first guide plate 280, and then along the second guide plate 270 of the second guide plate 270 on the downstream side. The traveling direction is changed and the bending portion 271 is reached while being slightly displaced by bending, and passes while maintaining the sliding contact state. The leading edge of the sheet S that has passed through the bent portion 271 passes the boundary upstream of the detection range of the registration sensor 36, and the registration sensor 36 detects the leading edge of the sheet S.

Further, the leading edge of the sheet S advances downstream of the bent portion 271 of the second guide plate 270.
In this case, the PET film 85 of the first guide plate 280 and the PET film 73 of the second guide plate 270 exhibit a function of reducing sheet conveyance resistance, and are thick, strong, and thick like the square bottom drug bag Sd. Even in the case of the sheet S having a large deviation and a large stiffness deviation, it is possible to suppress the fluttering of the sheet leading edge between the guide plates 80 and 70.

  Further, the sheet S conveyed in the sheet conveying area J is sandwiched between the pair of conveying rollers 297a and 297b, and at the same time, the both surfaces located on the downstream side thereof are in contact with the two points of the bent portions 281 and 271 to be slightly curved. However, three points are supported.

At this time, the distance L1 between the bent portion 81 and the upstream side wall surface of the second guide plate 70 is sufficiently larger than the thickness of the tip including the sheet S, for example, the corner bottom portion 51 and the folded portion 53 of the corner bottom medicine bag Sd, The displacement of the square bottom 51 of the square bottom medicine bag Sd that slides while slightly curving the upstream side wall surface of the second guide plate 70 can be facilitated, and the sliding resistance here can be reliably reduced.
Similarly, the distance L2 between the bent portion 271 of the second guide plate 270 and the downstream side wall of the first guide plate 80 is sufficiently larger than the thickness of the leading end including the sheet S, for example, the corner bottom portion 51 and the folded portion 53 of the corner bottom medicine bag Sd. The square bottom medicine bag Sd passing between the first and second guide plates 280 and 270 in the sheet conveying direction can hold a gap between the opposing walls facing the bent portions 81 and 71, and the square bottom medicine bag. Even with Sd, it is possible to suppress an increase in received conveyance resistance and noise generation, and to move without causing blurring.

Next, the sheet S reaches the registration sensor 36 positioned immediately after the bent portion 71 of the second guide plate 70 and passes through the detection range upstream boundary 371 of the registration sensor 36, so that the leading edge of the sheet S is accurately stabilized. Detected.
In this case, the sheet S having the leading end reaching the registration sensor 36 is supported without blurring in a state where the whole is supported at three points, and there is no blurring of the leading end of the sheet S, so this passes through the detection range upstream boundary 371 of the registration sensor 36. By doing so, the leading edge of the sheet S is detected accurately and stably.

  Next, the sheet S moves toward the registration roller pair 221. Here, the distance L2 is maintained between the downstream side wall surfaces of the first second guide plates 280 and 270. For this reason, the sheet S supported at three points does not newly receive the conveyance resistance at the leading end side, and the increase or fluctuation of the conveyance resistance of the sheet S is suppressed, and the variation in the contact point of the registration roller pair with the nip portion is varied. Can be prevented. For this reason, there is no deviation in the amount of displacement in which the sheet S receives the conveying force of the conveying roller pairs 297a and 297b for a predetermined time after the leading end side of the sheet S comes into contact with the registration roller pair 221, and skew correction is performed. The amount of displacement is an appropriate amount. As a result, there is no delay in the sheet biting or non-uniform state of the sheet biting due to insufficient pressure applied to the nip portion of the registration roller pair, and the leading edge margin of the sheet is shortened or skewing occurs. This problem is prevented in advance.

Instead of the sheet conveying apparatus F employed in the second embodiment described above, any one of <Modification 1> to <Modification 4> described in the first embodiment is selectively used. In these cases, the same effects as those described in the first embodiment can be obtained.
Further, in each of the above-described embodiments and modifications, the present invention conveys and supplies the sheet S from the sheet storage means (paper feed tray) in the image forming apparatus such as the full-color printer 100 or the copying machine 200 to the image forming means main body. In the image forming apparatus of the full-color printer 100 or the copying machine 200 shown in FIG. 1 or the like, the fixing device 20 in the apparatus main body is described. Applying the sheet S discharged from the upper part of the sheet 211 with its leading end substantially upward toward the discharge trays 30 and 209 from the apparatus main body in a horizontal direction is applied to a sheet conveying apparatus. Also good.

The present invention also relates to a sheet transporting device that transports and supplies a sheet (sheet) from a sheet storage unit (paper feed tray) or a sheet stacking unit (paper feed table) to a printing unit main body in a printing apparatus including a stencil printing machine. You may apply also to an apparatus.
The present invention has described a tandem type image forming apparatus that transfers images to an endless intermediate transfer belt as an intermediate transfer member and then transfers them to a sheet in a full color printer 100. However, a sheet (sheet) is conveyed by the transfer member. However, the present invention can be similarly applied to a direct transfer tandem color image forming apparatus that sequentially transfers and superimposes.

In the copying machine 200 as the image forming apparatus described above, a document to be read is set manually. However, an ADF (automatic document feeder) for automatically reading a plurality of documents (sheets) is provided. The sheet conveying apparatus of the present invention may be applied to the ADF in an equipped copying machine or printing apparatus.
Further, the image forming apparatus is not limited to a printer or a copying machine, but is an facsimile, an ink jet recording apparatus, an image reading apparatus of an image reading apparatus mainly having an image reading function having a scanner for reading an image from a document, or the like. You may apply to the multifunctional device etc. which combined at least 2 of these. In any case, it is possible to provide an optimum sheet conveying apparatus in a device or apparatus that needs to change the sheet conveying direction while saving space on the sheet conveying path.

  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. Is obvious.

3 Detection range upstream boundary 6 First transport means (first transport means)
7 Second transport means (second transport means)
8, 8C Belt conveying means (movement guide means)
15, 215 Paper feeders 17a, 17b Conveying rollers (conveying means)
18a, 18b Registration rollers 36, 236 Registration sensor (detection means)
37 registration sensor optical axis 371 detection range upstream boundary 50, 250 apparatus main body 62 refeed path 70 second guide plate 71 bent portion (protrusion) of second guide plate
72, 82 Registration sensor opening 80 First guide plate 81 Bent portion (projection) of first guide plate
100 Full color printer (image forming device)
200 Copying machine (image forming device)
A to F Sheet conveying devices A1 to F1 Skew correction means J Sheet conveying area (part of sheet conveying path)
S, Sa to Sc sheet (recording medium, image forming medium)
Sd Square bottom medicine bag R1 Transport path R2 Manual feed path R3 Reverse transport path

JP-A-11-292353 (FIGS. 1 to 3) JP 2006-341935 A (FIGS. 3 and 4) JP 2004-338923 A (FIGS. 2 to 4)

Claims (14)

A sheet conveying apparatus that conveys a sheet from a conveying means to a sheet conveying area and corrects skew by skew correcting means,
A first guide means having a bent portion protruding to the sheet conveying area, and a second guide means having a bent portion extending opposite to the first guide means and protruding to the sheet conveying area; With
Detection means for detecting the leading edge of the sheet is disposed at a detection position in the vicinity of the downstream of the sheet conveyance direction of the bent portion of the second guide means,
When the sheet is detected by the detection means, the first guide means and the second guide means simultaneously contact the bent portion of the first guide means and the bent portion of the second guide means downstream of the bent portion. A sheet conveying apparatus, characterized in that guide means is arranged.   When the sheet passes through the bent portions of the first guide means and the second guide means in the sheet conveyance direction, a gap is formed between the facing wall disposed facing the bent portions and the sheet. The sheet conveying apparatus according to claim 1, wherein the sheet conveying device is held.   3. The sheet conveying area according to claim 1, wherein the sheet conveying area has a registration roller pair on the downstream side of the second guide means, and the detection means is arranged on the upstream side of the registration roller pair. Sheet conveying device.   4. A friction reducing member is provided on the surface of both the first guide means and the two guide means, or one of the first guide means and the second guide means. Sheet transport device.   The bent portion of either one of the first guide means and the two guide means, or one of the first guide means and the second guide means is formed on an outer peripheral portion of the rotating member. The sheet conveying apparatus according to any one of 1 to 4.   The sheet conveying apparatus according to claim 5, wherein the rotating member includes a driving unit.   The sheet conveying apparatus according to claim 1, wherein the bent portion of the second guide means has a rib.   The sheet conveying apparatus according to any one of claims 1 to 7, wherein the second guide unit is rotatable and includes a mounting portion for the detection unit.   9. The sheet conveying apparatus according to claim 1, wherein the conveying unit is wider than a sheet width in a direction perpendicular to the sheet conveying direction.   The sheet conveying apparatus according to claim 1, wherein the conveying unit is a pair of rollers having the same hardness.   An image forming apparatus comprising the sheet conveying device according to claim 1.   An image reading apparatus comprising the sheet conveying apparatus according to claim 1.   An image forming apparatus comprising the sheet conveying device according to claim 1 or the image reading device according to claim 12.   14. The image forming apparatus according to claim 13, wherein the image forming apparatus is any one of a copying machine, a facsimile machine, a printer, a printing machine, and an ink jet recording apparatus, or a complex machine combining at least two of them. apparatus.

Images