JP2011057398A - Image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem wherein a user feels uncomfortable from noises generated when a sheet is conveyed to a resist part for forming an image, a tip end hitting noise caused by collision of a sheet tip end to a resist roller or a loop collision noise caused by collision of a loop part of a sheet formed for skew correction to a resist front guide, generated as noises on forming images. <P>SOLUTION: An upside conveying surface around an area where the sheet tip end part abuts on the upper side conveying surface of the resist front guide part is formed to be flat and, on the upper side conveying surface, a plurality of ribs are juxtaposed upstream of the flat part in the conveying direction to receive the loop part formed in skew correcting of a sheet material. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an image forming apparatus such as a copying machine, a printer, a facsimile, and a composite machine having a function of forming an image on a sheet, and particularly corrects skew of a sheet material conveyed toward an image forming unit. The present invention relates to a noise reduction technique for reducing noise generated in a resist portion.

  Conventionally, in an image forming apparatus such as a copying machine, when copying is started by pressing a copy button, a sheet material is supplied from a cassette, and is temporarily positioned by a registration roller through a pre-registration guide section from a vertical path conveyance path. stand by.

  At the same time, the original image read by the image reading unit is scanned and exposed on a photosensitive drum as an image carrier by the laser beam emitted according to the image information reflected by a polygon mirror that rotates at high speed by a porin motor. A latent image is formed on the photosensitive drum. Then, the latent image is made visible by the developing toner of the developing device and moves to the transfer position, while the sheet material waiting by the registration roller moves toward the transfer position so as to be synchronized with the toner image, and serves as transfer means. Are transferred to the sheet material by the transfer roller.

  The sheet material to which the toner image has been transferred is conveyed to a fixing device, where the image is fixed by the fixing device, and is discharged from the paper discharge unit onto the paper discharge tray, completing the copy.

  Various measures to shorten the first copy time because the user's satisfaction with the image forming apparatus increases as the series of copy operation time (hereinafter referred to as the first copy time) in which one copy is completed after the copy button is pressed is shorter. Has been made. For example, during a series of copying operations, the sheet feeding time and the paper discharging time other than transferring the image on the photosensitive drum to the sheet material increase the speed at which the sheet material is conveyed.

  However, in such an image forming apparatus, the conveyance speed of the sheet material is increased in order to shorten the first copy time. Therefore, the sheet material conveyed from the cassette is a registration roller at twice or more than the normal process speed. Will collide with. As a result, the user may feel uncomfortable due to the collision sound generated when the sheet material collides with the registration roller and the pre-registration guide portion upstream of the registration roller (hereinafter referred to as the registration portion). is there.

  A proposal has been made to deal with such a problem by providing a conveyance direction changing member that abuts the leading end of the sheet material on the upper conveyance surface of the pre-registration guide portion as proposed in Patent Document 1.

  By the way, the sheet material bends in order to remove the skew in the resist portion, and a part of the bent portion (hereinafter referred to as a loop portion) comes into contact with the upper conveyance surface of the pre-registration guide portion, thereby generating a noise “passing”. appear. The above-mentioned proposal in Patent Document 1 leaves room for improvement with respect to such noise reduction. Therefore, for such a problem, a buffer means (specifically, a sheet-like material made of a polyester film) that alleviates the impact caused by the contact of the loop portion as proposed in Patent Document 2 before the proposal in Patent Document 1 described above. It is also possible to respond by providing a member. Therefore, much of the noise generated by the sheet material at the resist portion can be reduced by the improvement plan according to Patent Document 2 in addition to Patent Document 1 (particularly, collision sound). In this section, the description by illustration is omitted due to the description of the patent document number.

JP 2002-128318 A Japanese Patent Laid-Open No. 7-257779

  However, in addition to the above-mentioned Patent Document 1, in the countermeasure against the noise reduction in the resist part according to Patent Document 2, the leading edge part (so-called edge part) of the sheet material conveyed to the resist part is rubbed against the above-mentioned buffer means. Since it is conveyed, there is a problem that the rubbing noise increases as compared with the case where the resist portion having a configuration not taking this countermeasure is provided. In particular, such noise becomes remarkable in a sheet material having a large basis weight (= high rigidity). Further, the above-described buffer means is provided as a separate member in the resist front guide portion, and in the image forming apparatus that is required to be reduced in price due to the member itself or the installation number of the member, the manufacturing cost is reduced. There is also the problem of leading to a rise in

  The present invention relates to a resist unit provided for removing skew in the conveying direction of a sheet material fed and conveyed from a sheet material stacking unit, and a pair of upper and lower resist guide units for guiding the sheet material to the resist unit. And a guide portion for guiding the leading end of the sheet material formed and conveyed on one guide of the pre-registration guide portion to the other guide, wherein the other guide is on the resist means side And a pre-registration guide portion formed in this order from the flat portion toward the upstream side in the sheet material conveyance direction, and the convex portion toward the one guide.

  In the image forming apparatus of the present invention, the upper conveyance surface in the vicinity of where the leading edge portion of the sheet material whose conveyance direction is changed by the conveyance direction changing member contacts the upper conveyance surface of the pre-registration guide portion is formed in a flat shape. In addition, a plurality of ribs having apexes at positions 40 mm to 60 mm upstream from the registration rollers and the like on the upper conveyance surface are arranged in parallel on the upper conveyance surface, and the skew correction of the sheet material is performed by the plurality of ribs. The loop part that is sometimes formed is received. As a result, it is possible to reduce the collision noise (= the tip impact noise and the loop collision noise) that is generated when the sheet material is conveyed at the registration portion, and at the same time, it is possible to prevent the generation of the rubbing noise. Further, since the plurality of standing ribs are integrally formed with the upper conveyance surface, it is possible to suppress an increase in the manufacturing cost of the image forming apparatus in the resist portion.

Overall schematic configuration (sectional view) showing an image forming apparatus according to an embodiment of the present invention The principal part enlarged view (sectional drawing) which shows the paper feeder which concerns on embodiment of this invention The principal part perspective view which shows the paper feeder which concerns on embodiment of this invention. The principal part enlarged view (sectional drawing) which shows the paper feeder which concerns on embodiment of this invention The principal part enlarged view (sectional drawing) which shows the paper feeder which concerns on embodiment of this invention The principal part perspective view which shows the paper feeder which concerns on other embodiment of this invention. Supplementary explanatory view showing a paper feeding device according to another embodiment of the present invention The principal part perspective view which shows the paper feeder which concerns on other embodiment of this invention. The figure which shows the effect in the paper feeder which concerns on embodiment of this invention

Example 1
An embodiment of the present invention will be described with reference to FIGS.

  First, the overall configuration of the image forming apparatus according to the present invention will be described with reference to FIG. In FIG. 1, an image reading unit A that reads image information of a document is arranged at the top of the image forming apparatus 1, and an image forming unit B that records an image according to the image information on a sheet S at the bottom. Has been placed.

  Cassettes 2 a and 2 b for storing sheets S are arranged in the image forming unit B. When copying is started, image information of a document (not shown) is read by the image reading unit 8 and is read by the lens 9. The light is condensed on the sensor 10 and converted into an image information signal. At the same time, the sheet S supplied from the cassette 2 a is conveyed along the conveyance path in the image forming unit B and is positioned by the registration roller pair 4.

  The image information signal is converted into an optical signal by a laser output unit (not shown), and the converted laser light L is reflected by a polygon mirror 17a that rotates at high speed by a motor 17 so as to be statically formed on the surface of the photosensitive drum 5. An electrostatic latent image is formed. The electrostatic latent image is visualized as a toner image by being supplied with toner from the developing sleeve 7 of the developing device 3 and becoming visible.

  The sheet S timed with the toner image by the registration roller pair 4 is conveyed between the photosensitive drum 5 and the transfer roller 6, and the toner image formed on the photosensitive drum 5 is transferred to the surface of the sheet S by the transfer roller 6. The Thereafter, the sheet S is transported by the transport device 11 and sent to the fixing device 12, and the toner image transferred by being heated and pressed by the fixing roller 12 a and the pressure roller 12 b provided in the fixing device 12 is transferred to the sheet. Fixed to S. The sheet S that has passed through the fixing device 12 reaches the conveyance path 15 formed so that the conveyance direction can be switched via the conveyance roller pair 13. For example, the sheet S is conveyed by switching a flapper provided in the conveyance path 15. The paper is conveyed to the pair of rollers 13 and the pair of outer paper discharge rollers 16 to be discharged out of the image forming apparatus 1 and stacked on the paper discharge tray 14.

  A pre-registration guide unit and a sheet for conveying the sheet S fed from the cassette 2a or 2b to the registration roller pair 4 near the center position on the right side of the image forming apparatus 1 in FIG. A material conveyance unit is arranged.

  FIG. 2 is a cross-sectional view for explaining in detail the configuration in an enclosure C in FIG.

  FIG. 3 is a perspective view of a part extracted from FIG. 2 for supplementary explanation of FIG.

  Hereinafter, based on FIG.2 and FIG.3, the characteristic of the pre-registration guide part and sheet material conveyance part of this invention is demonstrated in order of a code | symbol.

  Reference numeral 20 denotes a pre-registration guide portion. As shown in the figure, the pre-registration guide portion 20 is composed of a pair of upper and lower guides 21 and 22 in the upper and lower directions in the drawing. Reference numeral 21 a is a flat surface provided in the upper guide 21. The leading edge portion of the sheet S conveyed from the cassette 2a comes into contact with the flat surface portion 21a. Reference numeral 21 b is a plurality of ribs arranged in parallel to the conveyance direction of the sheet S so as to protrude toward the lower guide 22 in the upper guide 21, and is formed integrally with the upper guide 21. . The rib 21b is provided at a position to receive a loop portion formed for correcting the skew of the sheet S (details will be described later). Further, in this embodiment, the ribs 21b are arranged in parallel at equal intervals as shown in FIG. 3 (in this embodiment, the rib interval is about 30 mm. For the reasons described later, the rib interval should not be narrow). . The rib interval can be provided at an appropriate position according to the type (size) of the sheet that can be conveyed by the image forming apparatus 1, for example, the sheet S having a small width (a direction perpendicular to the conveyance direction). It is also possible to arrange the ribs 21b so that the interval near the center in the conveying direction of the ribs 21b is slightly narrowed so that the loops can be received by the ribs 21b (when image formation is based on a so-called central reference).

  Reference numeral 23 denotes a guide part for guiding the leading edge of the conveyed sheet S to the flat surface portion 21a, and the leading edge of the sheet S directly collides with the resist roller pair 4 that changes and stops the conveying direction of the sheet S. It prevents that. As a result, the collision noise generated when the leading edge of the sheet S collides with the registration roller pair 4 is reduced.

  Reference numeral 31 denotes a sheet material conveyance unit, which is composed of a pair of upper and lower conveyance guides 32, a conveyance guide lower 33, and a conveyance roller pair 34 in the figure as shown. The sheet S is conveyed toward the registration roller pair 4 by the conveyance roller pair 34 rotating in the direction of the arrow between the conveyance guide upper 32 and the conveyance guide lower 33. Reference numeral 35 denotes a manual sheet feeding unit, which is a sheet feeding unit that can also feed an irregularly sized sheet material that is not always stored in the cassettes 2a to 2b (description of each part in the manual sheet feeding unit is omitted). ). As shown in the figure, the image forming apparatus 1 is configured such that the conveyance path 35a from the manual feed and the conveyance paths from the cassettes 2a to 2b merge at the pre-registration guide unit 20 (the box C in FIG. 1 is also included). reference).

  FIG. 3 is a perspective view showing FIG. 2 in a state where the manual sheet feeder 35 is removed. In the drawing, it can be seen that the positional relationship between the flat portion 21a and the rib 21b in the upper guide 21 and that the rib 21b is arranged in a direction orthogonal to the conveying direction of the sheet S. 2 and 3, the sheet S is omitted, but it will be described again that the sheet S is conveyed in the direction indicated by the arrow in FIG. 2 from approximately lower right to approximately upper left in the drawing.

  Next, the state (behavior) before and after the collision of the sheet S with the registration roller pair 4 in the pre-registration guide portion 20 will be described with reference to FIGS. 4 and 5.

  FIG. 4 shows a state immediately after the sheet S collides with the upper guide 21 after reaching the pre-registration guide portion 20. Since the sheet S changes its conveying direction to the upper left direction in the drawing by the elastic guide portion 23, the leading end of the sheet S collides with the upper guide 21. By giving such a behavior to the sheet S, it is possible to reduce a collision sound (tip impact sound) generated at this time as compared with the case where the sheet S directly collides with the resist roller pair 4 that is stopped. . Here, the vicinity of the leading edge portion of the sheet S of the upper guide 21 (the portion 21a in the figure) is formed into a flat shape so that the leading edge portion does not contact the rib 21b. The fact that the skew is not promoted is the shape of the upper guide 21 and the behavioral characteristics of the above-described sheet S in the reduction of the collision sound (tip impact sound).

In FIG. 5, the sheet S is further conveyed from the state of FIG. 4, and the leading edge of the sheet S comes into contact with the pair of registration rollers 4 in the rotation stopped state, and a loop as illustrated is formed in the pre-registration guide portion 20. It shows the state. Here, the feature at the time of forming the loop of the sheet S in the present invention is that the loop portion is in contact with the rib 21b as shown in the figure. In this embodiment, the arrangement position of the rib 21b is determined by confirming the behavior by a sheet conveyance simulator that can simulate the behavior of the sheet S, and is arranged at an appropriate position for receiving the loop portion on the upper guide 21. Has been established. Specifically, the position of the rib 21b is set so that the apex position of the rib 21b is 40 to 60 (mm) upstream from the registration roller pair 4 along the lower guide 22 in the sheet S conveyance direction. Yes. Here, the basis weight of the sheet S confirmed by the simulator is about 60 to about 130 (g / m ² ). In a sheet having a large basis weight (for example, a sheet having a basis weight of about 210 (g / m ² ) or more), the loop formation is slight, and the loop portion does not collide with the upper guide 21, so that a collision sound (loop portion collision sound) is not generated. Therefore, it cannot be the direct object of improvement shown in the present invention. When it is difficult to confirm the behavior by the simulator, a method of confirming the actual behavior of the sheet S in the pre-registration guide unit 20 using a high-speed camera or the like is necessary. Further, regarding the determination of the arrangement position of the rib 21b, since the sheet having a larger basis weight has higher rigidity or larger mass, a collision sound (loop section collision sound) when the loop section collides with the upper guide 21 is generated. Therefore, it is necessary to prioritize a sheet with a larger basis weight among the target sheet materials in terms of design. Because of the circumstances as described above, the shape and arrangement position of the rib 21b are only shown as examples in the present embodiment, and details of each may be different for each image forming apparatus. It can be said.

  With the arrangement of the rib 21b described above, in the present invention, when the loop portion of the sheet S collides with the rib 21b, the loop portion can be deformed so that it slightly enters the gap between the ribs 21b. As a result, the collision sound (loop part collision sound) can be reduced. Therefore, if the interval between the ribs 21b is too narrow, the sheet S is deformed at the time of a loop collision and it becomes difficult to enter between the ribs 21b, so the noise reduction effect is diminished. When transporting A4 landscape sheets, a rib spacing of about 30 to 50 (mm) is proposed (as described above, 30 mm is used in the present invention). Further, in the present invention, it is possible to prevent the rubbing noise that has been generated harmfully as described in the background art and problems.

  In the state of FIG. 5 (= occurrence state of the loop portion collision sound), the effect of this embodiment was confirmed by a seat noise simulator capable of calculating the noise generated by the seat S. From this calculation result, it was found that the noise of about 3 to 4 (dB) can be reduced by arranging the rib 21b in parallel with the upper guide 21 (by comparison of the overall value at 200 to 5000 (Hz)). FIG. 10 shows a frequency spectrum obtained by this calculation (horizontal axis: frequency, vertical axis: sound pressure). The solid line in the figure is the frequency characteristic of the embodiment, and the broken line in the figure is the frequency characteristic when there is no rib, and shows a comparison of sound pressure with and without the rib 21b. As shown in the figure, it can be seen that the sound pressure level when the rib 21b is present is lower than when the rib 21b is absent. In this figure, the frequency band to be displayed is set to ~ 2.5 (KHz) for easy viewing of the graph display.

  As described above, in the pre-registration guide portion 20 and the sheet material conveyance portion 31 in the present invention, the upper guide 21 is formed with the flat portion 21a and the plurality of ribs 21b from the registration roller pair 4 side toward the upstream side. It has become possible to reduce the impact sound (tip impact sound and loop part impact sound) generated when S passes through the resist portion. That is, according to the present invention, the noise generated when the sheet S passes through the pre-registration guide portion 20 can be reduced without any harmful effect, and it is possible to provide an image forming apparatus in which the noise reduction is achieved more than before. Become.

(Example 2)
Next, another embodiment of the present invention will be described with reference to FIGS. In the description of the present embodiment, only the difference from the above-described first embodiment will be described, and the same components will be denoted by the same reference numerals and the description thereof will be omitted. Here, the difference between the sheet feeding apparatus in the present embodiment and the sheet feeding apparatus in the first embodiment is a rib shape erected on the upper guide of the pre-registration guide portion.

FIG. 6 is a perspective view showing the upper guide 41 in this embodiment. As shown in the drawing, a plurality of ribs (reference numerals 41b _{1 to} 41b ₉ ) standing in parallel in the direction orthogonal to the conveying direction of the sheet S are ribs 41b (← 41b _{1 to} 41b ₉ is a generic name, and the same applies to the following).

FIG. 7 is a view for easy understanding of the change in the height of the rib 41b, and is a view seen from the direction of arrow A (= sheet S conveyance direction) in FIG. As shown in the figure, the ribs 41b _{1 to} 41b ₉ are formed so that their heights (reference numerals h1 to h9) become lower from the right in the figure toward the left in the figure. By forming the ribs erected on the upper guide so as to gradually differ in height as shown in this figure, when the loop is formed in the sheet S, the loop portion is aligned at once (at the same time). without colliding with the rib 41b that is set, it will collide with one after the other direction from the rib 41b ₁ side to the rib 41b _9. That is, since the collision timing between the loop portion and the rib 41b can be shifted in time, the collision sound (= loop) generated when the sheet S further passes through the resist portion as compared with the first embodiment. Part collision sound) can be reduced. This embodiment is an embodiment in which the effect can be easily obtained when applied to a small image forming apparatus in which the pre-registration guide portion and the sheet material conveyance portion (inside the box C in FIG. 1) are close to the exterior portion of the apparatus. In the present embodiment, the height of the ribs _{41b h1> ··· h n ···>} h9 (n = 2 to 8) but is set to, may be shaped in an inverse relationship (h1 <· · H _n ... <H9 (n = 2 to 8)), and although not shown, for example, the shape may be such that h5 is the highest and h1 and h9 are the lowest. .

  In this embodiment, the number of ribs 41b is nine. However, the number of ribs 41b is not limited to this, and may be determined as appropriate depending on the type of sheet that can be conveyed (usually according to the specifications of the image forming apparatus). A flat surface portion 41a is formed on the downstream side of the rib 41b. The flat surface portion 41a has the same function as the flat surface portion 21a described in the first embodiment, and the sheet S is The front edge of the sheet S collides before colliding with the registration roller pair 4.

(Example 3)
Next, another embodiment of the present invention will be described with reference to FIG. In the description of the present embodiment, only differences from the above-described first and second embodiments will be described, and the same components are denoted by the same reference numerals and the description thereof is omitted.

  Here, the difference between the sheet feeding apparatus in the present embodiment and the sheet feeding apparatus in the first and second embodiments is the shape of the upper guide of the pre-registration guide portion.

  FIG. 8 is a perspective view showing the upper guide 51 in this embodiment. As shown in the figure, the upper guide 51 is formed with a plurality of openings 51b in parallel with the direction in which the sheet S is conveyed. These openings 51 b are provided so as to include a portion where the loop portion comes into contact with the upper guide 51 when a loop is formed in the sheet S. A specific arrangement position of the opening 51b is set for each image forming apparatus by checking the behavior of the sheet by the above-described simulator or high-speed camera. When the loop portion collides with the upper guide 51, the loop portion can be deformed so that it slightly enters the opening 51b, so that the impact at the time of collision can be reduced. As a result, it is possible to reduce the collision sound (loop part collision sound), and the same effect as the reduction of the loop part collision sound in the collision between the loop part and the rib 21b or 41b in the first and second embodiments is achieved. A flat portion 51a is formed on the downstream side of the rib 51b, and the flat portion 51a has the same function as the flat portions 21a and 41a described in the first and second embodiments. The leading edge portion of the sheet S collides before the sheet S collides with the registration roller pair 4. In the present embodiment, the rib 21b or 41b in the first and second embodiments is used for the convenience of the configuration of the image forming apparatus in the conveyance path of the sheet S (not illustrated, but, for example, restrictions on the shape of the conveyance path from the manual sheet feeding unit) It can be applied when the upper guide cannot be molded.

4 Registration roller pair 20 Pre-registration guide portion 21 Upper guide 21a Plane portion 21b Rib 22 Lower guide 31 Sheet material conveying portion 32 Upper conveying guide 33 Lower conveying guide 41 Upper guide 41b Rib 51 Upper guide 51b Opening portion S Sheet material

Claims (5)

A resist unit provided for removing skew in the conveyance direction of the sheet material fed and conveyed from the sheet material stacking unit; a pair of upper and lower resist guide portions for guiding the sheet material to the resist unit; and the resist In an image forming apparatus having a guide portion for guiding a leading end of a sheet material formed and conveyed in one guide of a front guide portion to the other guide,
The other guide includes a pre-registration guide portion that is formed in the order of a plane portion and a convex portion toward the one guide from the registration means side toward the upstream side in the sheet material conveyance direction. An image forming apparatus.   2. The image forming apparatus according to claim 1, wherein the convex portion has a vertex position of 40 mm to 60 mm away from the registration means upstream in the sheet material conveyance direction.   The image forming apparatus according to claim 2, wherein the convex portions are a plurality of rib forming portions arranged in parallel in a direction orthogonal to the sheet material conveyance direction.   The image forming apparatus according to claim 3, wherein the plurality of ribs have different rib heights gradually in a direction perpendicular to the sheet material conveyance direction.   The other guide is formed in order from the resist means side toward the upstream side in the sheet material conveyance direction, such as a flat portion and a plurality of openings formed in parallel in the direction orthogonal to the sheet material conveyance direction. The image forming apparatus according to claim 1, wherein:

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