JP2007076875A - Sheet feeding device and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sheet feeding device capable of feeding a sheet into an image forming device main body and coping with a thick sheet having a bulge due to a pasted part and an inlet flap like an envelope flexibly to enable smooth feeding and prevent improper conveyance. <P>SOLUTION: A middle plate 312 for loading the thick sheet S like the envelope is energized in the direction for pushing it upward by a pushing-up spring 311, the envelope is also pushed upward, and an envelope at the highest position is lifted up to a level position for enabling feeding by a pick-up roller 3. Height of loading of the envelopes is regulated by a pressing member 314 (a regulation member). Since amount of bulging is absorbed by upward bending and displacing of the pressing member 314 when a bulging part occurs due to the pasted part and the flap in the envelope, the pressing member 314 is not caught in the bulge to feed sheets stably. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a sheet feeding apparatus provided in an image forming apparatus such as a copying machine, a facsimile machine, a printer, and a multifunction machine.

  In general, an image forming apparatus includes a sheet feeding device that separates stacked sheets one by one with a pickup roller and sends the separated sheets toward an image forming unit. In recent years, the use of a wide variety of sheets other than fixed-size cut sheets has been rapidly increasing, and the size of the sheet stacking portion of the sheet feeding apparatus can be variably adjusted in accordance with the size of the sheets. For example, in the case of thick sheets such as envelopes and postcards for address printing and the like, there are a wide variety of sizes and types from narrow to wide. Therefore, there is a limit in adjusting the stacking unit of the sheet feeding device according to the size of the thick sheet such as an envelope.

  Further, as an example of a thick sheet, particularly in the case of an envelope, there is a bulge due to a bonded portion or an entrance flap. When such an envelope is picked up one by one from the state of being stacked on the stacking portion of the sheet feeding apparatus and separated and fed, the force to be fed out in the sheet feeding direction by the pickup roller due to bulging or the like becomes larger than usual. . For this reason, sheet feeding defects such as fluctuations in pressing force due to rotational friction of the pick-up roller, causing feeding failure, double feeding that feeds multiple sheets at once, continuous feeding that sends out sheets with no gaps, etc. It is easy to cause.

  In order to solve such a problem, a structure has been proposed in which an attachment dedicated to an envelope is detachably attached to an existing sheet cassette and a sheet is fed (see, for example, Patent Document 1). This is an example of the structure of the sheet feeding apparatus shown in FIGS. 9 and 10A and 10B, which will be described.

  As shown in FIG. 9, an intermediate plate 2 serving as a stacking portion is provided in the housing of the sheet cassette 1. The intermediate plate 2 is supported through a hinge 304 so as to be movable up and down, and is lifted up to a level position where the sheet S can be fed by a lifting mechanism provided in the image forming apparatus main body. In addition, a pair of side regulating plates 301 that regulate by contacting the widthwise ends of the sheet S are provided in the casing of the sheet cassette 1, and a trailing edge regulating plate that regulates by contacting the trailing end of the sheet S 302 is provided.

  10A and 10B show cross sections of the sheet cassette 1 in a direction orthogonal to the sheet feeding direction from the front side to the back side in the drawing. An envelope cassette 305 is detachably attached to the middle plate 2 by an attachment method. A mounting pin 307 protrudes from the bottom plate 306 of the envelope cassette 305, and the mounting pin 307 is engaged with a mounting hole 308 provided in the bottom plate of the sheet cassette 1. Thereby, the envelope cassette 305 is simply attached to the sheet cassette 1.

  The envelope cassette 305 is provided with a pair of side regulating plates 309 that regulate the end portions in the width direction of the envelope so that the width can be adjusted. The side regulating plate 309 is provided with a pair of opposing pressing members 313 for pressing the bulge of the envelope and the opening of the flap on the upstream side in the feeding direction, and a claw-shaped pressing member 315 is also provided on the downstream end. Is provided. Further, a guide hole 316 is formed in the side restricting plate 309, and a guide blade (not shown) and a recess provided therein are engaged with the guide hole 316 in the middle plate 312 so that the envelope of the side restricting plate 309 is provided. Guide the slide adjustment in the width direction. Further, the middle plate 312 is urged upward by a push-up spring (not shown) attached to the bottom plate 306. As a result, the envelopes stacked on the intermediate plate 312 are pushed up to hit the claw-shaped pressing member 315 and stand by at a position where the pickup roller 3 can feed the envelope.

  Accordingly, the sheets S stacked in the sheet cassette 1 or the envelopes stacked in the envelope cassette 305 are fed out by the pickup roller 3 and separated and fed one by one by the cooperative action of the feed roller 4 and the retard roller 5. Is done.

  Here, as shown in FIGS. 10A and 10B, when a normal cut sheet such as plain paper is fed from the sheet cassette 1 or when an envelope which is a thick sheet is fed, the pickup roller 3 is as follows. Behaves like

  First, in the case of feeding a sheet S based on a normal cut sheet, when it is detected that the plain paper sheet cassette 1 is loaded by a cassette detection sensor provided in the main body of the image forming apparatus, the pickup is performed by operation control based on the detection signal. The roller 3 starts to descend. At this time, since the sheet surface is at a position lower than the feeding level, the pickup roller 3 is lowered to the fourth level position (d) indicated by a two-dot chain line in FIG. The intermediate plate 2 is raised by the lifting mechanism until the pickup roller 3 is pushed by the rising sheet surface and returns to the first level position (a). The pickup roller 3 is initially present at the first level position (a) indicated by the solid line in FIG. At the time of sheet feeding, the pickup roller 3 descends to the feeding position, that is, the second level position (b) indicated by the broken line in FIG. 10B where a predetermined pressure is applied to the sheet surface, and feeds at this position. Let it begin. When the feeding is finished, the pickup roller 3 returns to the first level position (a). Thereafter, the operation is repeated.

  As the number of sheets S stacked in the sheet cassette 1 decreases, the pickup roller 3 is greatly lowered to the third level position (c) indicated by the one-dot chain line in FIG. When the sensor detects that the pickup roller 3 is greatly lowered, the lifting mechanism is operated to feed the pickup roller 3 at the second level position (b), and the intermediate plate 2 is raised. Further, at the moment when the sheet cassette 1 is mounted, the pickup roller 3 also starts to descend. At this time, since the paper surface is much lower than the paper feed position, the pickup roller 3 descends beyond the third level position (c). Then, the pickup roller 3 is once lowered to the fourth level position (d) indicated by a two-dot chain line. Thereafter, the intermediate plate 2 is raised by the lifting mechanism, and the pickup roller 3 is raised until it is pushed by the paper surface and returned to the first level position (a).

  On the other hand, when the envelope is fed from the envelope cassette 305, the pickup roller 3 is initially waiting at the first level position (a) separated from the envelope surface. At the start of feeding, the pickup roller 3 is lowered to a feeding position, that is, a second level position (b) where a predetermined pressure is applied to the envelope surface, where rotation is started and the envelopes are fed one by one to perform a feeding operation. Is called. When the feeding is finished, the pickup roller 3 returns to the first level position (a).

  In the meantime, the envelope or sheet S is urged together with the middle plate 312 in the direction of being pushed up by the push-up spring so that the uppermost one of the envelope or sheet S always abuts against the claw-shaped pressing member 314.

JP 09-315610 A

  By the way, the sheet feeding apparatus shown in FIGS. 9 and 10A and 10B has the following problems.

  When an thick sheet having a flap or a flap is fed like an envelope, the bulge or an open flap may be caught by a feeding port and cause a conveyance failure. For example, a claw-shaped pressing member 315 is provided in the vicinity of the pickup roller 3, but an envelope bulge, a flapper, or the like may be caught on the pressing member 315, causing a feeding failure. A possible reason for this is that the pressing member 315 is fixed without changing from its height position. In other words, if a thick sheet such as an envelope has a bulge or the like, it can be prevented from being caught on the pressing member 314 if the bulge is fluctuated to escape flexibly.

  Therefore, the object of the present invention is to prevent a conveyance failure by enabling flexible feeding and smooth feeding even in the case of a thick sheet having a bulge caused by a bonded portion or an entrance flap like an envelope. It is to provide a sheet feeding apparatus.

  In order to achieve the above object, the sheet feeding device according to the present invention is provided with a regulating member that presses the uppermost sheet of the sheet bundle stacked on the sheet stacking member so as to be displaceable in the sheet stacking height direction. It is a feature.

  The image forming apparatus according to the present invention includes a sheet feeding device for feeding a sheet, and an image forming unit for forming an image on the sheet fed by the sheet feeding device. It is a feature.

  According to the sheet feeding device of the present invention, the swelling and bulkiness of the stacked sheets are displaced and absorbed in the direction in which the regulating member escapes. Thereby, the thick sheet can be stably conveyed without being caught by the regulating member.

  In addition, according to the image forming apparatus of the present invention, even when the sheet sent to the image forming apparatus is thick, the sheet is stably fed from the sheet feeding apparatus without jamming such as a jam. Therefore, the total productivity of image formation can be maintained.

  Hereinafter, a preferred embodiment of the sheet feeding apparatus according to the present invention will be described in detail with reference to the image forming apparatus shown in FIG. In the description of the sheet feeding apparatus according to the present embodiment, the same reference numerals are given to the members corresponding to those shown in FIGS. Shows a difference with a new code.

  As shown in FIG. 8, the image forming apparatus main body A includes an image reading scanner unit B that reads an image surface of a document, an image forming unit C that forms an image based on image information of the read image surface, and an image forming unit C. It consists of a sheet feeding device D as a sheet deck mounted at the bottom. The scanner unit B includes a scanning light source 201, a platen glass 202, a document pressure plate 203 that can be opened and closed with respect to the platen glass 202, a mirror 204, a lens 205, a light receiving element (photoelectric conversion element) 206, an image processing unit, and the like. Yes. Image information obtained by reading a document on the platen glass 202 is processed by an image processing unit, converted into an electrical signal, and transmitted to the laser scanner 111.

  Further, in the sheet feeding apparatus D, one feeding unit is configured by combining two upper and lower stages of a lower cassette 1a and an upper cassette 1b (hereinafter collectively referred to as a sheet cassette 1) serving as a main cassette body. Yes. The illustrated example is a total of six cassette mounting structures by three feeding units U1, U2, and U3.

  First, as shown in the image forming apparatus of FIG. 8, the sheet S accommodated in the sheet cassette 1 in the sheet feeding apparatus is fed out by the pickup roller 3, and the cooperative action of the feed roller 4 and the retard roller 5. Are separated and fed one by one. The sheet S is conveyed by the conveying rollers 104 and 105 and guided to the registration roller 106, and is fed to the image forming unit C by the registration roller 106 in synchronization with the image forming operation.

  In the image forming unit C, the photosensitive drum 112 whose surface is uniformly charged by the primary charger 110 is scanned by the image writing optical system 113 with laser light corresponding to the image information emitted from the laser scanner 111. A latent image is formed. Next, a toner image is formed on the photosensitive drum 112 by visualizing the latent image with the developing device 114. The toner image on the photosensitive drum 112 is transferred to the first surface of the sheet conveyed by the registration roller 106 in synchronization with the rotation of the photosensitive drum 112 by the transfer charger 115.

[Sheet feeding device]
(First embodiment)
As shown in FIGS. 1 and 2, a sheet cassette 1 as a main cassette body corresponds to feeding of a normal cut sheet S such as plain paper. When feeding an envelope, a dedicated envelope cassette 305 is a sheet cassette. 1 is detachable as an attachment. As shown in FIG. 9, the envelope cassette 305 is attached to the sheet cassette 1 by engaging the attachment pin 307 and the attachment hole 308 with almost one touch.

  However, although it is limitedly described as the envelope cassette 305 here, an attachment-type cassette that is used for address printing or the like by feeding a thick, stiff paper-like thick sheet like a postcard to the image forming unit. Shall also be included.

  The envelope cassette 305 has both side regulating plates 309 that abut against both ends of the envelope width in the direction orthogonal to the feeding direction of the envelope and regulate movement, and abut against the rear end of the envelope feeding direction to regulate movement. A rear end regulating plate (not shown) is provided to form an envelope stacking section that regulates the positional deviation of the envelope. The side regulating plate 309 and the rear end regulating plate can be adjusted by sliding movement to a position corresponding to the envelope size by operating an operating mechanism (not shown).

  Further, the envelope stacking portion has a middle plate 312 and, as shown in FIGS. 3A and 3B, is urged in a direction to push the middle plate 312 upward from below by a push-up spring 311 locked to the bottom of the cassette. is doing. Therefore, the envelope loaded and held on the intermediate plate 312 is also pushed upward, and the uppermost envelope is lifted up to a level position where it can be fed by the pickup roller 3.

  Further, in the sheet feeding apparatus of the present embodiment, a pressing member (regulating member) for regulating the sheet stacking height as described below is provided.

  Even if the envelope is jammed at the nip portion of the pickup roller 3, the holding member 314 is provided with an envelope so that the sheet cassette 1, which is the main cassette body, can be easily removed from the image forming apparatus body for repair. Regulate the loading height. In other words, the pressing member 314 presses the uppermost one of the envelopes from the top and regulates it so that the jammed envelope is not caught on the cassette guide rail.

  In order to prevent the stacking height of the stacked envelopes from exceeding a certain dimension, a pair of pressing members 314 for pressing the uppermost envelope from above are provided on opposite sides of the cassette perpendicular to the envelope feeding direction. Attached to each of the. As shown in FIGS. 2 and 3A and 3B, the pressing member 314 is disposed in the vicinity of the both ends where the rotation axis of the pickup roller 3 extends, and the envelope member 314 is placed on the intermediate plate 312. Press down on the top surface in contact with the top. The envelope is stacked so that the stacking height of the envelope does not exceed a certain size. The envelope stacking height position that does not exceed the fixed dimension is lower than the cut sheet stacking set height position when normal cut sheets such as plain paper or thin cut sheets are fed from the sheet cassette 1.

  By restricting the stacking height of the envelope in such a manner by being pressed by the pressing member 314, the thick dedicated feeding path is positioned away from the guide rail of the sheet cassette 1. That is, when it becomes necessary to remove the sheet cassette 1 from the image forming apparatus main body, the envelope feeding path is not obstructed.

  The pressing member 314 is fixed to the side regulating plate 309 by being coupled to the side regulating plate 309 via the elongated plate spring (elastic body) 202 by the fixing portion 201. Due to the elastic force of the leaf spring 202, a pressing biasing force Fa acts on the pressing member 314 in the direction of pressing the stacking envelope downward from the figure. On the other hand, the intermediate plate 312 is pushed up and biased by the push-up spring 311. Therefore, the loaded envelopes are pushed down from above by the push-down biasing force Fa by the pressing member 314, pushed up from below by the push-up biasing force Fb by the intermediate plate 312, and held by being pressed from above and below. In this case, the pushing biasing force Fa from above is set to be equal to or more than the pushing biasing force Fb from below. In other words, the balance is set such that Fa = Fb or Fa> Fb.

  When feeding the envelope, when the pickup roller 3 starts to rotate downward from the steady position, the uppermost one of the envelope is fed out from the pickup roller 3 and fed between the feed roller 4 and the retard roller 5, and the envelope is fed in the feeding direction. It is conveyed while moving obliquely upward toward the downstream side. At that time, in addition to the push-up biasing force Fb that the push-up spring 311 pushes the envelope together with the intermediate plate 312, a roller conveying force Fc that is pulled into the nip portion between the feed roller 4 and the retard roller 5 is applied to the envelope. Work in the direction. As a result, as shown in FIG. 3B, the pressing member 314 is bent and displaced obliquely upward against the pressing biasing force Fa by the leaf spring 202. The relationship of forces among Fa, Fb, and Fc at that time is expressed by the following equation.

Fb ≦ Fa ≦ Fb + Fc (1)
In addition, there may be a so-called double feed in which several envelopes are fed out by the pickup roller 3 at a time and sent to the nip portion between the feed roller 4 and the retard roller 5. Even in such a case, from the relationship of the force shown in the relational expression (1), the pressing member 314 is displaced so as to bend against the leaf spring 202 and escape upward, and the dimensional bulge and bulk caused by several envelopes Absorb and avoid tension.

  This is the same even when the envelope is bulged due to the bonded portion or the entrance flap, or when the entrance flap is opened, and the holding member 314 is flexibly deformed and displaced upward, and the bulge or bulk is increased. It does not get caught by avoiding contact with the tension. As a result, the feeding resistance acting on the pickup roller 3 does not increase and remains unchanged, and stable feeding is realized.

  The first embodiment has the following effects. Envelopes and postcards are so stiff that if the curvature of the curved portion is small in the middle of the conveyance path, the conveyance resistance of the envelope passing through the envelope increases, which may cause conveyance failure or jamming. Increasing the curvature of the curved portion of the conveyance path is effective to some extent for preventing conveyance failure and jamming. On the other hand, however, there is a problem that if the curved portion is enlarged, the image forming apparatus main body is increased in size. In this respect, in the first embodiment, the holding member 314 can reduce the conveyance resistance from the beginning of feeding, and the curvature of the curved portion of the conveyance path does not have to be increased in order to stably convey the envelope. That is, it is effective to suppress the increase in size of the image forming apparatus main body.

  In addition, in the first embodiment, in order to stabilize the feeding of a thick sheet such as an envelope, at least one of the pressing members 314 provided as a pair of opposite sides on both sides of the cassette is at both ends of the rotation axis of the pickup roller 3. It is provided in the vicinity where it faces. That is, by arranging the pressing member 314 on the upstream side in the sheet feeding direction as close as possible to the pickup roller 3, the stacking height of thick sheet materials such as envelopes can be regulated at the position of the pickup roller 3, and at the time of feeding Stable feeding can be performed while suppressing sheet twisting.

(Second Embodiment)
Next, FIG. 4 shows a sheet feeding apparatus according to the second embodiment. In the first embodiment, the elongate leaf spring 202 is coupled to the pressing member 314 to urge the envelope from the top down. On the other hand, in the present embodiment, the leaf spring 202 is omitted, and the base end portion of the long pressing member 314 is connected by the hinge (rotation fulcrum) 203 at the fixing portion 201 to the side regulating plate 309. is there. In this case, the urging force of the leaf spring 202 is substituted by the weight of the long pressing member 314. That is, the long pressing member 314 is made rotatable by the hinge 203 at the base end, and the top end of the long pressing member 314 is brought into contact with the topmost one of the envelope from above and pushed down. There is an effect that the number of members can be reduced by omitting the leaf spring 202.

(Third embodiment)
FIG. 5 shows a third embodiment as a modification of the second embodiment shown in FIG. In this case, if the long pressing member 314 has insufficient weight to press the envelope from above, a coil spring (a pressing biasing means) 204 is attached to strengthen the pressing biasing force and Gain power Fa.

(Fourth embodiment)
FIGS. 6A, 6B, and 7 show a sheet feeding apparatus according to a fourth embodiment, to which the second and third embodiments are further applied. In this case, a rotating roller (rotating body) 205 is pivotally supported on a free end portion of a long pressing member 207 via a spindle pin 206. By pushing down the uppermost envelope from above using the rotary roller 205 as a pressing portion, the conveyance resistance can be made smaller than in the above embodiments. In addition to the upward escaping action of the entire pressing member 207, the resistance is reduced more than the sliding friction by the rotational friction by the rotating roller 205, so that the thick sheet can be more stably conveyed.

  As mentioned above, although several embodiment of the said invention was described above, this invention is not limited to these embodiment, If it is in the range which does not deviate from the main point of this invention, other embodiment and application examples And variations and combinations thereof are possible.

  For example, in each of the above-described embodiments, the case where the pickup roller 3 is provided as the feeding rotating body for feeding the thick sheet envelope from the sheet feeding device is shown, but an endless belt may be used instead.

FIG. 3 is a side cross-sectional view illustrating a main part of the sheet feeding apparatus according to the first embodiment. FIG. 3 is a perspective view illustrating the sheet feeding apparatus according to the first embodiment. FIGS. 4A and 4B are side cross-sectional views showing the sheet feeding operation in the first embodiment. FIG. 6 is a side cross-sectional view illustrating a main part of a sheet feeding device according to a second embodiment. FIG. 10 is a side cross-sectional view illustrating a main part of a sheet feeding device according to a third embodiment. The same figure (a), (b) is side sectional drawing which shows the sheet | seat feeding operation | movement in 4th Embodiment. The perspective view which shows the sheet feeding apparatus of 4th Embodiment. 1 is an overall view showing an example of an image forming apparatus to which the present invention is applied. FIG. 3 is a perspective view illustrating a conventional sheet feeding device provided in the image forming apparatus. FIGS. 4A and 4B are side cross-sectional views showing an operation example of the sheet feeding apparatus.

Explanation of symbols

1 Sheet cassette 3 Pickup roller (feed rotating body)
4 Feed roller 5 Retard roller 202 Leaf spring (biasing means)
203 Rotation fulcrum 204 Coil spring (pushing-down biasing means)
206 Rotating roller (Rotating body)
207 Presser member 305 Envelope cassette 309 Side regulating plate 311 Middle plate push-up spring (push-up biasing means)
312 Middle plate 314 Holding member (regulating member)

Claims (9)

  A sheet feeding apparatus comprising: a regulating member that presses a topmost sheet of a sheet bundle stacked on a sheet stacking member so as to be displaceable in a sheet stacking height direction.   The sheet feeding device according to claim 1, wherein the regulating member is supported by an elastic body that is elastically deformed.   The sheet feeding device according to claim 1, wherein the regulating member is supported such that one end of the regulating member that can hold the sheet is rotatable about the other end.   The sheet feeding apparatus according to claim 3, further comprising a push-down biasing unit that biases the restriction member in a direction of pushing down the uppermost sheet.   A push-up biasing means for biasing the sheet stacking member in the direction of pushing up is provided, and the biasing force by the push-down biasing means of the regulating member is set to be equal to or greater than the biasing force by the push-up biasing means. The sheet feeding apparatus according to claim 4.   The sheet feeding device according to any one of claims 1 to 5, wherein a rotating body is provided in a portion of the regulating member that presses the sheet, and the surface of the uppermost sheet is pressed through the rotating body. apparatus.   A feeding rotator for picking up the uppermost sheet is provided, and the regulating member is provided in the vicinity of an end of the feeding rotator in the rotation axis direction on the upstream side of the feeding rotator in the sheet feeding direction. The sheet feeding apparatus according to any one of claims 1 to 6.   A sheet cassette that stores sheets of normal size; and a thick sheet cassette that is detachably provided in the sheet cassette and stores thick sheets; and the stacking height of the thick sheets regulated by the regulating member, The sheet feeding device according to any one of claims 1 to 7, wherein the sheet feeding height is set lower than a stacking height of the normal size sheets stacked on the sheet cassette when the thick sheet cassette is not mounted. Feeding device. A sheet feeding apparatus according to any one of claims 1 to 8, for feeding a sheet,
And an image forming unit for forming an image on the sheet fed by the sheet feeding device.

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