JP5958789B2 - Sheet feeding apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to a sheet feeding apparatus that feeds a sheet, and an image forming apparatus including the sheet feeding apparatus.

  Various image forming apparatuses such as a copying machine, a printer, a facsimile, or a complex machine of these are equipped with a sheet feeding device that separates and feeds stacked sheets such as originals and recording sheets one by one. As a feeding method used in this sheet feeding apparatus, a method of separating sheets by using a frictional force by a feeding roller, a method of separating sheets by air suction, and the like are known.

  However, in the method of separating the sheets using the frictional force, a rubber material or the like is used for the feeding roller. Therefore, the frictional force changes due to a change with time such as wear, and the feeding performance is lowered. Also, when sheets with different friction coefficients or sheets with different friction coefficients are separated and fed at the same time, feeding failures such as multiple feeding of multiple sheets at the same time or inability to separate sheets occur. Sometimes. Furthermore, the sheet may be soiled due to the configuration in which the pressure is applied and separated when the sheet is fed.

  On the other hand, the separation feeding method using air suction is a non-friction separation method that does not depend on the friction coefficient of the roller or the sheet, but requires an air suction blower and an air duct. The sound becomes noise and is unsuitable for use in an office or the like.

  Therefore, an electrostatic attraction separation method that separates a sheet by forming an electric field on a dielectric belt and bringing it into contact with the sheet and adsorbing it has been proposed (for example, a patent document). 1). This type of sheet feeding device can be broadly divided into a “surface charging type” that alternately charges uniformly while changing the polarity of the belt surface, and an “embedded electrode” in which electrodes of different polarities are alternately embedded inside the belt. There is "type". However, when the dielectric belts used for these are manufactured by joining them endlessly, a dielectric material such as an electrode may not be provided at the joint for manufacturing reasons. When a dielectric belt having such a joint is used, if there is a joint portion on the suction surface of the belt during suction conveyance of the sheet, the suction force does not occur or decreases at that portion, so the sheet peels off from the belt. There is a risk of falling. For this reason, there has been a problem that the sheet cannot be stably conveyed.

  Conventionally, as measures against peeling off of the sheet from the belt, for example, a method of detecting the peeling of the sheet from the belt by a sensor (see Patent Document 2), or holding by a holding roller so that the sheet does not peel off from the belt. And the like (see Patent Document 3) have been proposed.

  However, the method of detecting the peeling of the sheet with the sensor is not a fundamental solution because even if the peeling of the sheet can be detected in advance, the peeling of the sheet itself cannot be prevented. Further, in the case of a method of holding a sheet with a holding roller, there is a problem that parts such as a roller are separately required and the apparatus is increased in size.

  Therefore, in view of such circumstances, the present invention provides a sheet feeding device capable of reliably adsorbing a sheet to a dielectric belt and feeding the sheet while suppressing an increase in size of the device, and the sheet feeding device. An image forming apparatus is provided.

In order to solve the above-mentioned problems, an invention according to claim 1 is provided with an endless dielectric belt rotatable in the circumferential direction and a belt charging means for charging the dielectric belt, and the dielectric charging belt is used for the dielectric. A sheet feeding device that charges a body belt, attracts the sheet to the lower surface of the dielectric belt, and feeds the sheet without transferring an image onto the sheet. In a sheet feeding apparatus having a low suction area with a lower suction force than other areas in the part, all areas where the dielectric belt contacts the sheet at the start of suction of the sheet and at the time of suction feeding are all other than the low suction area It is characterized by the fact that it becomes an adsorption region.

  According to the first aspect of the present invention, when the sheet is sucked and fed, the low suction region having a low suction force can be prevented from coming into contact with the sheet, and the sheet can be peeled off from the dielectric belt. Can be prevented. This makes it possible to realize stable sheet feeding even in a configuration using a dielectric belt having a low adsorption region in a part of the circumferential direction.

  In addition, according to the first aspect of the present invention, the sheet can be reliably adsorbed to the dielectric belt and fed without separately providing a holding roller or the like that holds the sheet so as not to peel off from the belt. The increase in the size of the apparatus can be suppressed, contributing to the downsizing.

1 is a schematic configuration diagram of a copying machine according to an embodiment of the present invention. FIG. 2 is a schematic configuration diagram of a paper feeding unit provided in the copying machine. It is the figure which expanded a part of the circumferential direction of the dielectric belt. It is a figure which shows the structure using a contact-type sensor as a rotation position detection means. It is a figure which shows the structure which provided the to-be-detected part in the inner peripheral surface of the dielectric material belt. It is a figure which shows the structure which provided the notch part in the tension roller. It is explanatory drawing of paper feeding operation | movement. It is explanatory drawing of paper feeding operation | movement. It is explanatory drawing of paper feeding operation | movement. It is explanatory drawing of paper feeding operation | movement. It is explanatory drawing of paper feeding operation | movement. It is a figure for demonstrating the setting conditions of the standby position of a low adsorption area | region.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In addition, in each drawing for explaining the embodiment of the present invention, components such as members and components having the same function or shape are once described by giving the same reference numerals as much as possible. The description is omitted.

FIG. 1 is a schematic configuration diagram of a copying machine as an image forming apparatus according to an embodiment of the present invention.
The copying machine 1 includes an automatic document feeder 2 that separates documents one by one from a bundle of documents stacked on a document tray 2a, and automatically feeds a document conveyed on contact glass by the automatic document feeder 2. A document reading unit 3 to be read, an image forming unit 5 that forms an image based on an image of the document read by the document reading unit 3, a transfer unit 8 that transfers an image formed by the image forming unit 5 to a sheet, and a transfer A paper feed unit 6 that feeds the paper to the unit 8, a fixing unit 14 that fixes the image transferred by the transfer unit 8 to the paper, and a paper discharge that discharges the paper on which the image has been fixed by the fixing unit 14 to the outside. Part 15.

  The image forming unit 5 mainly includes image forming units 7Y, 7M, 7C, and 7Bk for yellow, magenta, cyan, and black, and an exposure device 9 as a latent image forming unit.

  The exposure device 9 converts color-separated image data input from a personal computer, a word processor, or the like, or image data of a document read by the document reading unit 3 into a signal for driving a light source, and accordingly each laser light source unit An internal semiconductor laser is driven to irradiate a light beam.

  The image forming units 7Y, 7M, 7C, and 7Bk have the same configuration except that toners of different colors of yellow, magenta, cyan, and black are accommodated. Specifically, the image forming units 7Y, 7M, 7C, and 7Bk respectively include a photosensitive member 10 as a latent image carrier that is driven to rotate, a charging unit 11 that is disposed around each photosensitive member 10, and a developing unit. 12, the cleaning unit 13 and the like. In FIG. 1, only the photoconductor 10, the charging unit 11, the developing unit 12, and the cleaning unit 13 included in the yellow image forming unit 7 </ b> Y are denoted by reference numerals, and in the other image forming units 7 </ b> M, 7 </ b> C, and 7 </ b> Bk. The symbol is omitted.

  Each photoconductor 10 is a photoconductor drum formed in a cylindrical shape, and is rotationally driven by a drive source (not shown). Each charging unit 11 uniformly charges the surface of the corresponding photoconductor 10 so as to have a predetermined potential. The charging unit 11 of the present embodiment employs a contact charging type that performs charging processing by bringing a charging member such as a charging roller into contact with or close to the surface of the photoreceptor 10. Each developing unit 12 visualizes the electrostatic latent image as a toner image by attaching toner to the electrostatic latent image on each photoconductor 10. In the present embodiment, the developing unit 12 employs a non-contact developing type that supplies toner to the photoreceptor 10 in a non-contact state. Each cleaning unit 13 removes foreign matters such as residual toner adhering to the surface of each photoconductor 10. In this embodiment, the cleaning unit 13 employs a brush contact type that performs cleaning by bringing a brush into contact with the surface of the photoreceptor 10. Note that the photoconductor 10, the charging unit 11, the developing unit 12, and the cleaning unit 13 are not limited to the configuration described above.

  The paper feed unit 6 accommodates a sheet bundle on which a plurality of sheets P are stacked. The paper feeding unit 6 feeds paper to the transfer unit 8 in order from the topmost paper P1 located at the top of the paper bundle.

  The transfer unit 8 includes an intermediate transfer belt 16 composed of an endless belt as an intermediate transfer member, four primary transfer rollers 17 as primary transfer means, and a secondary transfer roller 18 as secondary transfer means. Yes. The intermediate transfer belt 16 is stretched by a plurality of stretching rollers as stretching members, and when one of them is driven to rotate, the intermediate transfer belt 16 rotates (circulates). .

  Each primary transfer roller 17 is in contact with the inner peripheral surface of the intermediate transfer belt 16 at a position facing each photoconductor 10, whereby the primary transfer is performed at a position where the intermediate transfer belt 16 and each photoconductor 10 are in contact. A nip is formed. Each primary transfer roller 17 is connected to a power source (not shown), and a predetermined direct current voltage (DC) and / or alternating current voltage (AC) is applied to the primary transfer roller 17.

  The secondary transfer roller 18 is in contact with the outer peripheral surface of the intermediate transfer belt 16 at a position facing one of the stretching rollers. As a result, a secondary transfer nip is formed at a location where the secondary transfer roller 18 and the intermediate transfer belt 16 abut. Similarly to the primary transfer roller 17, the secondary transfer roller 18 is connected to a power source (not shown) so that a predetermined direct current voltage (DC) and / or alternating current voltage (AC) is applied to the secondary transfer roller 18. It has become. In addition, a pair of registration rollers 19 as a conveying unit that conveys the sheet to the secondary transfer nip is disposed upstream of the secondary transfer roller 18 in the sheet conveying direction (lower side in the drawing).

The basic operation of the copying machine will be described below with reference to FIG.
When the image forming operation is started, the photoconductors 10 of the image forming units 7Y, 7M, 7C, and 7Bk are rotationally driven, and the surfaces of the photoconductors 10 are uniformly charged to a predetermined polarity by the charging units 11. The Next, the exposure device 9 irradiates the charged surface of each photoconductor 10 with a light beam based on the image information of the original read by the original reading unit 3, and an electrostatic latent image is formed on the surface of each photoconductor 10. Is done. The electrostatic latent image formed on the photoconductor 10 in this manner is supplied with toner by each developing unit 12, whereby the electrostatic latent image is visualized (visualized) as a toner image.

  Subsequently, a roller that stretches the intermediate transfer belt 16 is rotationally driven to rotate the intermediate transfer belt 16. Further, by applying a constant voltage having a polarity opposite to the toner charging polarity or a voltage controlled by a constant current to each primary transfer roller 17, a primary transfer nip between each primary transfer roller 17 and each photoconductor 10. A transfer electric field is formed. Then, the toner images of the respective colors on the respective photoreceptors 10 are sequentially superimposed and transferred onto the intermediate transfer belt 16 by the transfer electric field formed in the primary transfer nip. Thus, the intermediate transfer belt 16 carries a full-color toner image on its surface. Further, the toner on each photoconductor 10 that could not be transferred to the intermediate transfer belt 16 is removed by the cleaning unit 13.

  On the other hand, the stored paper P is fed from the paper feed unit 6. The fed paper P is timed by the registration roller 19 and sent to the secondary transfer nip between the secondary transfer roller 18 and the intermediate transfer belt 16. At this time, a transfer voltage having a polarity opposite to the toner charging polarity of the toner image on the intermediate transfer belt 16 is applied to the secondary transfer roller 18, thereby forming a transfer electric field in the secondary transfer nip. The toner images on the intermediate transfer belt 16 are collectively transferred onto the paper P by the transfer electric field formed in the secondary transfer nip.

  Thereafter, the paper P on which the toner image is transferred is conveyed to the fixing unit 14, and the toner image on the paper P is fixed on the paper P. The paper P is discharged onto the paper discharge tray 20 by a pair of paper discharge rollers provided in the paper discharge unit 15.

  The above description is an image forming operation when a full-color image is formed on a sheet. A single-color image is formed using any one of the four image forming units 7Y, 7M, 7C, and 7Bk, and 2 Two or three image forming units can be used to form a two-color or three-color image.

FIG. 2 is a schematic configuration diagram of the paper feeding unit.
As shown in FIG. 2, the sheet feeding unit 6 includes a sheet feeding cassette 21 serving as a stacking unit that can stack a plurality of sheets of paper P and the like, and a sheet feeding unit that feeds sheets one by one from the sheet feeding cassette 21. And a paper feeding device 22 as a feeding device. In FIG. 2, a plurality of sheets P are stacked on the bottom plate 23 of the paper feed cassette 21, and the bottom plate 23 can be moved up and down by a lifting mechanism 24 provided below the bottom plate 23. Sheets that can be stacked in the paper cassette 21 include plain paper, thick paper, postcards, envelopes, thin paper, coated paper (coated paper, art paper, etc.), tracing paper, OHP sheets, and the like.

  The sheet feeding device 22 includes an endless dielectric belt 27 stretched by two stretching rollers (stretching members) 25 and 26, a belt charging unit 28 for charging the dielectric belt 27, and a dielectric belt. Rotation position detection means 31 that detects the rotation position of the 27 and a conveyance roller pair (conveyance rotating body pair) 32 that conveys the paper P.

  The dielectric belt 27 is disposed above the sheet bundle loaded in the sheet feeding cassette 21, and the surface of the dielectric belt 27 facing the uppermost sheet P1 of the sheet bundle is the uppermost sheet P1. Are arranged in parallel with each other. At least one of the two stretching rollers 25 and 26 is a driving roller, and when the driving roller is rotationally driven by a driving source (not shown), the dielectric belt 27 can rotate in the direction indicated by the arrow in the figure. It has become. Further, the tension roller 26 on the right side of the figure is grounded.

  The belt charging unit 28 includes a charging power source 29 that generates alternating current, and a pair of electrode members 30 that are connected to the belt charging unit 28 and abut against the inner peripheral surface of the dielectric belt 27. The alternating current generated by the charging electrode 29 is applied to the dielectric belt 27 via the electrode member 30, so that the surface is alternately and uniformly charged while changing the polarity, and the adsorption force for adsorbing the sheet is obtained. Occur.

  In this embodiment, a roller-shaped electrode member is used, but a blade-shaped or brush-shaped electrode member may be used. Further, the voltage applied to the electrode member 30 may change the direct current to a high and low alternating potential. In the present embodiment, the dielectric belt 27 is a “surface charge type” that can be alternately and uniformly charged while changing the polarity of the surface thereof, but electrodes having different polarities are alternately embedded in the belt. An “embedded electrode type” may be used.

FIG. 3 is an enlarged view of a part of the dielectric belt in the circumferential direction.
The dielectric belt 27 of the present embodiment is formed by joining both ends of a sheet-like member having a predetermined length, and as shown in FIG. 3, there is a joint portion A at a part in the circumferential direction. A dielectric is not provided in the joint portion A and the vicinity thereof for manufacturing reasons. For this reason, the adsorbing force is lower in the joint portion A and in the vicinity thereof than in the other portions. That is, the dielectric belt 27 has a low adsorption region in a part of its circumferential direction. In FIG. 2, this low adsorption region is indicated by a black portion B. It should be noted that the “low suction region” includes a region in which suction force is not generated at all in addition to a region where suction force is generated but lower than other regions.

  Further, as shown in FIG. 2, a detected portion 33 that is detected by the rotational position detecting means 31 is provided on the outer peripheral surface of the low suction region B. In the present embodiment, a reflection type optical sensor is used as the rotational position detection means 31, and the reflection type optical sensor detects a difference in the amount of reflected light between the portion where the detected portion 33 is provided and the other portions. Thus, the rotational position of the dielectric belt 27 is detected. For example, when the dielectric belt 27 itself is made of a highly reflective member, it can be detected by a reflective optical sensor by applying a black tape as the detected portion 33. Further, the reflectance may be changed by coloring or directly processing the surface of the dielectric belt 27 without attaching a tape.

  Further, as shown in FIG. 4, a contact type sensor can be used as the rotational position detecting means 31. In this case, as the dielectric belt 27 rotates, the detected portion 33 provided on the outer peripheral surface of the low adsorption region B comes into contact with the filler of the contact sensor so that the rotational position of the dielectric belt 27 is detected. Is done. The detected part 33 used here is preferably a rubber material or a sponge material that is highly flexible to the extent that the rotational operation of the dielectric belt 27 is not hindered.

  Further, as shown in FIGS. 5A and 5B, the detected portion 33 may be provided on the inner peripheral surface of the dielectric belt 27 and detected by a non-contact sensor or a contact sensor. Good. As described above, when the detected portion 33 is provided on the inner peripheral surface, the detected portion 33 is not easily contaminated and is not easily influenced by external light. Therefore, the detection system is improved particularly when an optical sensor is used. There is an advantage such as. On the other hand, when the detected portion 33 is provided on the outer peripheral surface, there is an advantage that the rotational position detecting means 31 can be easily arranged.

  In addition, as shown in FIG. 6, when the detected portion 33 is provided on the inner peripheral surface of the dielectric belt 27, each of the stretching rollers 25 and 26 avoids interference with the detected portion 33. Notches 25a and 26a may be provided. As a result, the detected portion 33 is not sandwiched between the stretching rollers 25 and 26 and the dielectric belt 27, so that the rotation of the dielectric belt 27 can be further stabilized.

Hereinafter, a paper feeding operation of the paper feeding device 22 of the present embodiment will be described.
First, in FIG. 7, an alternating current is generated by the charging power source 29, and the dielectric belt 27 is alternately and uniformly charged while changing the polarity of the surface thereof. Next, the dielectric belt 27 is rotated, and the detected portion 33 is detected by the rotation position detecting means 31. Thereby, the rotational position of the dielectric belt 27 is detected.

  Thereafter, the rotation of the dielectric belt 27 is continued, and the rotation of the dielectric belt 27 is stopped when the low adsorption region B reaches a predetermined standby position as shown in FIG. Specifically, in the present embodiment, the low adsorption region B is stopped at a position on the right side of the drawing that is slightly moved in the belt rotation direction from the surface of the dielectric belt 27 facing the uppermost sheet P1.

  Thereafter, the bottom plate 23 of the sheet cassette 21 is raised, and the uppermost sheet P 1 is brought into contact with the dielectric belt 27. At this time, the rising of the bottom plate 23 is stopped, and the uppermost sheet P1 is attracted to the dielectric belt 27 to be charged. Then, when the fixed time has elapsed and the suction of the paper P1 is completed, the bottom plate 23 is lowered and stopped as shown in FIG. As a result, the uppermost sheet P1 is held while being attracted to the dielectric belt 27, and the uppermost sheet P1 is separated from the lower sheets.

  Thereafter, as shown in FIG. 10, the uppermost sheet P <b> 1 is fed by rotating the dielectric belt 27. The uppermost sheet P1 is fed to the conveying roller pair 32 provided on the downstream side in the feeding direction of the dielectric belt 27, but the dielectric sheet 27 is held until the leading edge of the sheet P1 is nipped by the nip portion of the conveying roller pair 32. The charging (adsorption force) of the body belt 27 is maintained.

  As shown in FIG. 11, the charging of the dielectric belt 27 is released when the leading edge of the uppermost sheet P <b> 1 is sandwiched between the nip portions of the conveyance roller pair 32. This release of charging is maintained at least until the uppermost sheet P1 is conveyed to a position where it is not re-adsorbed by the dielectric belt 27. Thereafter, the uppermost sheet P1 is further conveyed downstream by the rotating conveyance roller pair 32. Thereby, the paper feeding operation by the paper feeding device 22 is completed. Further, when feeding the next and subsequent sheets, this series of sheet feeding operations is repeated.

  As described above, in the present embodiment, the low suction area B is made to wait at a predetermined standby position before starting the suction of the paper and is not disposed at a position facing the uppermost paper P1. (See FIG. 8). At the start of suction, the low suction area B does not come into contact with the uppermost sheet P1 (see FIG. 9). Furthermore, even if the dielectric belt 27 is rotated thereafter, the low suction region B does not come into contact with the uppermost sheet P1 (see FIGS. 10 and 11). As described above, in the present embodiment, the contact area of the dielectric belt 27 with the uppermost sheet P1 at the start of suction of the sheet and at the time of suction feeding is set to be a suction area other than the low suction area B. Yes.

Hereinafter, the setting conditions for the standby position of the low suction region B will be described with reference to FIG.
First, in order to prevent the low suction area B from contacting the paper P at the start of suction, the standby position of the low suction area B needs to be set to an area other than the belt surface area that contacts the sheet at the start of suction. As shown in FIG. 12, in the case of the present embodiment, the range between the front end 27a in the feed direction and the rear end 27b in the feed direction on the flat bottom surface of the dielectric belt 27 facing the paper P is “adsorption”. Since the belt surface area is in contact with the seat at the start, the standby position must be set in other areas.

  Furthermore, in FIG. 12, when the front end b1 in the belt rotation direction of the low suction region B at the standby position is a start point, and the feed direction rear end 27b of the belt surface region that is in contact with the paper P at the start of suction is the end point, When the distance in the belt rotation direction is X, and the distance from the front end Pa in the feeding direction of the stacked paper P to the nip portion N of the transport roller pair 32 is Y, the standby position is set so that X> Y. Need to be set. By setting in this way, the low adsorption region B contacts the paper after the dielectric belt 27 that adsorbs the paper starts to rotate until the front end of the paper reaches the nip portion N of the conveying roller pair 32. Can be prevented.

  As described above, by setting the standby position of the low suction area B, it is possible to prevent the low suction area B having a low suction force from coming into contact with the paper when the paper is sucked and fed. Can be prevented from peeling off from the dielectric belt 27. As a result, even in a configuration using the dielectric belt 27 having the low adsorption region B in a part in the circumferential direction, it is possible to realize stable sheet feeding without causing sheet feeding failure.

  Further, according to the present embodiment, the sheet can be reliably adsorbed to the dielectric belt 27 and fed without a holding roller for holding the sheet so that the sheet is not peeled off from the belt. Downsizing and can contribute to downsizing.

  The embodiment of the present invention has been described above, but the present invention is not limited to the above-described embodiment, and it is needless to say that various modifications can be made without departing from the gist of the present invention. In the above-described embodiment, the case where the configuration of the present invention is applied to a sheet feeding device that feeds a recording sheet such as paper has been described as an example. However, the configuration of the present invention is also applied to a feeding device that feeds a document. Applicable. The sheet feeding apparatus according to the present invention includes a monochrome image forming apparatus, an ink jet type image forming apparatus, other copiers, printers, facsimiles, or a combination of these in addition to the above-described electrophotographic color copying machine. The present invention can also be applied.

1 Copier 22 Paper Feeder (Sheet Feeder)
27 Dielectric belt 28 Belt charging means 31 Rotation position detecting means 32 Conveying roller pair (conveying rotating body pair)
33 Detected part B Low suction area P Paper (sheet)

JP-A-5-139548 JP 2010-215307 A JP 2011-42428 A

Claims (10)

An endless dielectric belt rotatable in the circumferential direction; and belt charging means for charging the dielectric belt. The belt charging means charges the dielectric belt, and a sheet is placed on the lower surface of the dielectric belt. A sheet feeding apparatus that sucks and feeds an image without being transferred onto the sheet, wherein the dielectric belt has a low suction region having a lower suction force than other regions in a part of the circumferential direction thereof. In the sheet feeding apparatus having
2. A sheet feeding apparatus according to claim 1, wherein a region where the dielectric belt contacts with the sheet at the time of starting suction of the sheet and at the time of suction feeding is made to be a suction region other than the low suction region. A rotation position detecting means for detecting a rotation position of the dielectric belt;
The sheet feeding apparatus according to claim 1, wherein the sheet feeding device is configured to wait for the low suction area at a predetermined standby position before the start of sheet suction by the detection by the rotation position detection unit.   3. The configuration according to claim 2, wherein the low-adsorption region is made to stand by at a position moved in the belt rotation direction from the surface of the dielectric belt facing the sheet before the sheet adsorption starts by detection by the rotation position detection unit. The sheet feeding apparatus according to the description. The dielectric belt is stretched by two stretching members arranged on the upstream side and the downstream side in the feeding direction,
4. The configuration according to claim 3, wherein the low adsorption area is made to wait at a position corresponding to a position where the dielectric belt contacts the downstream tension member before the start of sheet adsorption by the detection by the rotation position detection unit. The sheet feeding apparatus according to the description. A sheet feeding device provided with a pair of conveying rotating bodies for conveying the sheet by rotating on the downstream side in the feeding direction of the dielectric belt,
In a region other than the belt surface region that comes into contact with the sheet at the start of suction, the low suction region is made to wait,
Further, the distance in the belt rotation direction when the front end in the belt rotation direction of the low suction region at the standby position is the start point and the rear end in the feeding direction of the belt surface region that is in contact with the sheet at the start of suction is the end point. 5. The apparatus according to claim 2, wherein X is set such that X> Y, where X is Y, and a distance from the front end in the feeding direction of the stacked sheets to the nip portion of the pair of conveying rotating bodies is Y. The sheet feeding apparatus according to item.   The sheet feeding device according to any one of claims 2 to 5, wherein a detected portion detected by the rotational position detecting means is provided in the low suction region.   The sheet feeding apparatus according to claim 6, wherein the detected portion is provided on an outer peripheral surface of the dielectric belt.   The sheet feeding apparatus according to claim 6, wherein the detected portion is provided on an inner peripheral surface of the dielectric belt.   9. The sheet feeding according to claim 8, wherein a notch portion for avoiding interference with a detected portion provided on the inner peripheral surface is provided on a tension member that rotatably stretches the dielectric belt. apparatus.   An image forming apparatus comprising the sheet feeding device according to claim 1.

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