JP6247553B2 - Medium supply apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to a medium supply device that supplies a medium such as paper, and an image forming apparatus including the medium supply device.

  2. Description of the Related Art In an image forming apparatus such as a printer, a paper feeding device as a medium supply device is provided to supply a medium (for example, paper) to an image forming unit that forms an image.

  For example, as disclosed in Patent Document 1, a conventional sheet feeding device includes a primary separation unit that performs a front winding operation to separate a plurality of sheets fed by a sheet feeding roller from a stacked state. And a secondary separation unit comprising a separation roller method or a separation pad method. The primary separation unit is disposed upstream of the secondary separation unit in the medium conveyance direction, and applies a conveyance load to the leading edge of the sheet fed from the sheet feeding roller using the inclined surface.

JP 2009-78887 A

  However, in the conventional paper feeding device, a gap for feeding paper is provided between the front-side primary separation unit and the secondary separation unit on the downstream side in the paper conveyance direction. Then, due to the friction between the sheets, a plurality of sheets of paper that could not be completely separated by the primary separation unit can pass through the gap between the primary separation unit and the secondary separation unit. Yes. For this reason, there is a problem that double feeding of paper occurs.

The medium supply device of the present invention, a feeding roller for feeding a plurality of media stacked by Rukoto given transport load to the plurality of media fed by the feeding roller, said plurality a primary separation unit for separating the media, when the plurality of medium supplied is abutted by passing through the primary separation unit, conveyance for conveying a plurality of sheets of the medium to the downstream side in the transport direction while have a roller and separation roller, characterized in that it comprises a secondary separation unit for further separating the plurality of media.

The primary separation unit is disposed on both sides in the width direction of the transport roller and at positions spaced from the transport roller, and obliquely upward from the feed roller toward the feed direction. An extending inclined portion and an elastic friction member for applying the transport load to the plurality of fed media. The upstream portion in the transport direction of the friction member is fixed on the inclined portion. A portion of the friction member on the downstream side in the conveyance direction is disposed at a position overlapping the conveyance roller when the conveyance roller is viewed from the axial direction, and protrudes from the inclined portion . when the plurality of media according to driving Ru is fed to the secondary separation unit by passing through the primary separating section, it is displaceable by Rukoto pushed down by the plurality of media. An end of the inclined portion on the downstream side in the conveyance direction is positioned above a straight line connecting a pressure contact between the feeding roller and the plurality of media and a pressure contact between the conveyance roller and the separation roller. To do.

The image forming apparatus of the present invention is characterized by comprising: a medium supply device of the invention, an image forming means for forming an image on the fed media body from the medium supply device.

According to the medium supply device and an image forming apparatus of the present invention, in the overlapping portion between the conveying roller primary separating section, top-level of the first sheet of media of a plurality of sheets of medium is dammed, one that The eye medium is transported by a transport roller. By primary separation unit in accordance with the conveyance of the first sheet of medium is displaced, the brake force is generated, by utilizing the braking force is second or subsequent medium dammed. Thereby, it is possible to prevent double feeding of media.

FIG. 1 is an enlarged side view showing the vicinity of the paper feeding unit 20 in FIG. FIG. 2 is a schematic configuration diagram showing the image forming apparatus 1 in Embodiment 1 of the present invention. FIG. 3 is an enlarged front view in which a part of the paper feeding unit 20 in FIG. 1 is omitted. FIG. 4 is an enlarged side view showing the paper feeding operation in the vicinity of the primary separation unit 25 in FIG. FIG. 5 is an enlarged side view showing the sheet feeding operation in the vicinity of the primary separation unit 25 in FIG. FIG. 6 is an enlarged side view showing the sheet feeding operation in the vicinity of the primary separation unit 25 in FIG. FIG. 7 is an enlarged side view showing the vicinity of the sheet feeding unit 20A according to the second embodiment of the present invention. FIG. 8 is an enlarged side view showing the vicinity of the primary separation portion 25A in FIG. FIG. 9 is an enlarged side view showing the vicinity of the primary separation portion 25A after the operation of FIG. FIG. 10 is an enlarged side view showing the operation in the vicinity of the paper feeding unit 20A in FIG. FIG. 11 is an enlarged side view showing the vicinity of the paper feed unit 20B in the third embodiment of the present invention. FIG. 12 is an enlarged side view showing the vicinity of the primary separation part 25B in FIG. FIG. 13 is an enlarged side view showing the operation in the vicinity of the sheet feeding unit 20B in FIG. FIG. 14 is an enlarged side view showing the operation in the vicinity of the paper feeding unit 20B in FIG.

  Modes for carrying out the present invention will become apparent from the following description of the preferred embodiments when read in light of the accompanying drawings. However, the drawings are only for explanation and do not limit the scope of the present invention.

(Configuration of Example 1)
FIG. 2 is a schematic configuration diagram illustrating the image forming apparatus 1 according to the first exemplary embodiment of the present invention.

  The image forming apparatus 1 is, for example, an electrophotographic printer that prints on a medium P that is paper, and includes a medium cassette 10, a paper feed conveyance path 14 as a medium supply conveyance path, a medium tray 15, and a medium supply apparatus. , An image forming unit 40 and a fixing unit 50 as image forming units, and a discharge conveyance path 55.

  The medium cassette 10 is detachably attached to the lower part of the image forming apparatus 1, and a plurality of stacked media P are accommodated therein. A feeding roller 11 for feeding the medium P in the medium transport direction is provided above the front end of the medium cassette 10. The medium P in the medium cassette 10 is brought into pressure contact with the feeding roller 11 by pressing means (not shown). A conveyance roller 12 and a separation roller 13 are arranged on the downstream side of the feeding roller 11 in the medium conveyance direction so that the medium P fed by the feeding roller 11 is separated into one sheet and sent to the paper feeding conveyance path 14. It has become.

  The medium tray 15 is for feeding a medium P (for example, a long sheet, a thin sheet, a thick sheet, or a narrow sheet) that cannot be handled by the medium cassette 10, and is attached to the main body of the image forming apparatus 1. On the other hand, it can be folded and stored. A stacking plate 16 on which the medium P is stacked is swingably provided on the medium tray 15, and a pressing spring 17 is provided below the front end of the stacking plate 16. A paper feed unit 20 is provided on the front end side of the medium tray 15.

  The paper feed unit 20 feeds the medium P stacked on the medium tray 15 to the image forming unit 40, and includes a paper feed roller 21, a transport roller 22, a separation roller 23, and the like as feed rollers. ing. A conveyance path 36 to the image forming unit 40 is formed continuously to the paper feeding unit 20. A paper feed detection sensor 37, a print timing adjustment unit 38, and a write timing sensor 39 are disposed in the conveyance path 36. The print timing adjustment unit 38 is composed of a pair of rollers.

  The image forming unit 40 forms a color image by superimposing the toner images as developer images of the respective colors of black (K), yellow (Y), magenta (M), and cyan (C) on the medium P. Are formed of four photosensitive drums 41K, 41Y, 41M, and 41C as an electrostatic latent image carrier, a transfer belt unit 42, and the like, and an image is formed on the medium P by an electrophotographic process. The medium P is synchronized with the image formation of the image forming unit 40 by the print timing adjusting unit 38, an image is formed on one side thereof, and the medium P is conveyed to the fixing unit 50 disposed on the downstream side in the medium conveying direction. .

  The fixing unit 50 heats and presses the medium P on which an image is formed to fix the image on the medium P, and includes a pair of rollers 51 and 52 that are pressed against each other with a predetermined pressure. Each of the rollers 51 and 52 includes a heater 51a and 52a for heating. A discharge detection path 53, a conveyance roller pair 54, and a discharge roller pair 56 are provided in the discharge conveyance path 55 that is continuous with the fixing unit 50. The conveyance detection sensor 53 detects the passage of the medium P on which the image is fixed by the fixing unit 50. The transport roller pair 54 and the discharge roller pair 56 are for transporting the fixed medium P to the discharge transport path 55 and discharging it to the outside of the apparatus.

FIG. 1 is an enlarged side view showing the vicinity of the sheet feeding unit 20 in FIG.
The paper feed unit 20 is provided with a paper feed roller 21 driven by a drive system (not shown). The paper feed roller 21 feeds the medium P stacked on the stacking plate 16 and pressed by the pressing spring 17. A semi-retarded secondary separation unit 24 including a conveyance roller 22 and a separation roller 23 that are pressed against each other by a predetermined pressure contact force is provided on the downstream side in the medium conveyance direction of the paper feed roller 21. In the semi-secondary secondary separation unit 24, the transport roller 22 is driven by a drive system (not shown), but the separation roller 23 is not driven by a drive system. A primary separation unit 25 is detachably fixed to the conveyance guide 26 between the paper feed roller 21 and the conveyance roller 22.

  The primary separation unit 25 is for winding the leading end of the medium P fed from the paper feed roller 21 and guiding the medium P to the transport roller 22. The primary separation unit 25 has an inclined portion 25a extending from the paper supply roller 21 in the feeding direction and obliquely upward. A friction member 25b is fixed to the surface of the inclined portion 25a only on the upstream side with a double-sided adhesive tape 25c. The fixing method may be other bonding or the like. The friction member 25b is provided at a position where the leading end of the fed medium P abuts, and applies a transport load to the fed medium P, thereby scooping the leading end of the medium P, and It has a function of guiding to the downstream side in the medium conveyance direction.

  The friction member 25b is formed of an elastic rubber piece made of, for example, EPDM (Ethylene-propylene diene monomer). The position of the downstream vertex 25d of the rubber piece is higher than the straight line indicated by the alternate long and short dash line connecting the paper contact roller 21 and the pressure contact 21a of the medium P and the pressure contact 24a of the transport roller 22 and the separation roller 23. (For example, the distance D1 = 4.0 mm above), and when viewed from the axial direction of the transport roller 22, it is disposed at a position overlapping the transport roller 22 (for example, the overlap amount D2 = 3.2 mm). .

  FIG. 3 is an enlarged front view in which a part of the paper feeding unit 20 in FIG. 1 is omitted, and is a diagram in which the paper feeding roller 21 is omitted and the paper feeding unit 20 is viewed from the plane perpendicular to the friction member 25b. .

  The friction member 25b is disposed on both sides of the transport roller 22 and the separation roller 23 at positions separated by a distance D3 (for example, 5 mm). That is, the friction member 25b and the transport roller 22 are disposed so as not to overlap in the transport direction of the medium P. The width W of the friction member 25b is, for example, 10 mm. The transport roller 22 is driven by a drive system (not shown). A torque limiter 27 for generating a braking force for braking the medium P is provided on the same axis as the axis of the separation roller 23. The torque limiter 27 itself is rotatably held and does not actively rotate, and a support shaft that supports the torque limiter 27 is fixed in the rotation direction.

(Printing operation of Example 1)
An operation for printing on the medium P fed from the medium tray 15 in the image forming apparatus 1 of FIG. 2 will be described.

  The medium P stacked on the stacking plate 16 on the medium tray 15 is pressed against the paper feed roller 21 by the pressing spring 17. The medium P is fed out when the paper feed roller 21 is rotated clockwise by a drive system (not shown). When a plurality of media P are fed out, only the uppermost (ie, the first sheet from the top) medium P is fed downstream in the medium conveyance direction by the primary separation unit 25 and the secondary separation unit 24 of the paper feeding unit 20. Sent to the image forming unit 40.

  When the medium P fed from the paper feed unit 20 is detected by the paper feed detection sensor 37, the print timing adjustment unit 38 synchronizes with the image formation by the image forming process (not shown) of the image forming unit 40. . Further, the leading edge of the medium P is detected by the write timing sensor 39, and the medium P is sent to the image forming unit 40. In the image forming unit 40, toner images of the respective colors are formed on the photosensitive drums 41K, 41Y, 41M, and 41C, and the toner images are transferred onto the medium P conveyed by the transfer belt unit 42. After the last cyan image is transferred, the medium P is sent to the fixing unit 50.

  In the fixing unit 50, the toner image on the medium P is fixed by heat and pressure by the pair of rollers 51 and 52 respectively heated by the heaters 51a and 52a. The medium P on which the image has been fixed is detected by the transport detection sensor 53, transported to the discharge transport path 55 by the transport roller pair 54, discharged to the outside by the discharge roller pair 56, and printing ends.

(Feeding operation of Example 1)
4 to 6 are enlarged side views showing the sheet feeding operation in the vicinity of the primary separation unit 25 in FIG.

A paper feeding operation in the paper feeding unit 20 will be described with reference to FIGS. 1 and 3 to 6.
In FIG. 1, the medium P stacked on the medium tray 15 is fed out by the paper feed roller 21. As shown in FIG. 4, the friction member 25b in the primary separation part 25 has a thickness of D4 (for example, 1 mm) and protrudes from the tip of the inclined part 25a by a length of D5 (for example, 5 mm). The medium P fed out by the paper feed roller 21 first strikes the friction member 25b of the primary separation unit 25. The front end portions of the plurality of media P are wound along the inclined surface of the friction member 25b due to the frictional force and inclination of the friction member 25b.

  However, as shown in FIG. 5, the medium P having high inter-medium friction and poor separation performance enters the intersecting point 25e between the conveying roller 22 and the friction member 25b in a state where the medium P is not fed by the inclined surface of the friction member 25b and is fed in a multiple manner. There are things to do.

  As shown in FIG. 6, the uppermost medium P1 (that is, the first sheet from the top) of the multi-feed medium that has entered the intersection 25e is the driving force of the transport roller 22 and the medium P1 that is in contact with the transport roller 22. The medium is fed downstream by the medium conveying force Fr in the direction of the arrow generated by the frictional force μr with the conveying roller 22. Then, the friction member 25b has the downstream apex 25d displaced to the position 25d-1 on the separation roller 23 side (for example, the displacement amount δ =) with the fixed end 25f of the primary separation portion 25 as to the inclined portion 25a as a fulcrum. 3.7 mm) to enable conveyance of the medium P1.

  Further, due to the reaction force generated by the displacement of the friction member 25b, the braking force Ft in the direction of the arrow for stopping the second medium P2 coming into contact with the friction member 25b increases in the vicinity of the fixing end 25f. As a result, the medium transport force Fr and the brake force Ft are sufficiently larger than the frictional force Fμp in the arrow direction between the medium P1 that contacts the transport roller 22 and the medium P2 that contacts the friction member 25b (Fr). , Ft >> Fμp). Therefore, only the first medium P1 from the top contacting the transport roller 22 is transported to the separation roller 23 on the downstream side, and the second medium P2 from the top contacting the friction member 25b is prevented from transporting. .

  The braking force Ft due to the displacement of the friction member 25b is determined by the dimensional relationship and characteristics of the friction member 25b. In Example 1, as shown in FIGS. 3, 4, and 6, the dimensional relationship is length D5 = 5 mm, thickness D4 = 1 mm, width W = 10 mm, displacement amount δ = 3.7 mm, and friction coefficient. μ = 0.83. When the friction member 25b is displaced, as shown in FIG. 3, the friction member 25b is disposed outside the extended region in the medium conveyance direction on both sides without touching the separation roller 23. 25 b does not interfere with the separation roller 23.

  When only one medium P is fed to the separation roller 23, the separation roller 23 is rotated around the medium P in the feeding direction by the conveyance force of the conveyance roller 22. As a result, the medium P is conveyed to the downstream paper feed detection sensor 37 shown in FIG. When the medium P sent from the transport roller 22 and the separation roller 23 is detected by the paper feed detection sensor 37 of FIG. 2, the print timing adjustment unit 38 synchronizes with the image forming operation of the image forming unit 40 as described above. And the image is transferred onto the medium P conveyed to the image forming unit 40.

(Modification of Example 1)
In the first embodiment, the following modifications (a) and (b) may be made.

  (A) Although the friction member 25b of the primary separation portion 25 is an EPDM rubber piece, the material of the friction member 25b is not particularly limited to this, and a friction coefficient such as a cork piece, felt, or sponge is used. It may be relatively high.

  (B) Although the configuration of the secondary separation unit 24 is a separation roller system composed of the conveying roller 22 and the separation roller 23, a separation pad system using a separation pad can be used instead of the separation roller 23. is there. It can be implemented in all separation methods using the friction separation method.

(Effect of Example 1)
According to the sheet feeding unit 20 and the image forming apparatus 1 according to the first exemplary embodiment, the primary separation unit 25 is disposed on both side surfaces of the conveyance roller 22 and at a position where they are overlapped when viewed from the conveyance roller axial direction. A gap through which the medium P passes is eliminated. Furthermore, since the downstream apex 25d of the friction member 25b in the primary separation unit 25 is displaced when the medium P passes through the gap portion, the first medium P1 from the top of the dam is transported by the transport roller 22. It is configured to pass by force.

  That is, in the first embodiment, the friction member 25b of the primary separation unit 25 is out of the extended region of the conveyance roller 22 in the medium conveyance direction and when viewed from the axial direction of the conveyance roller 22, Further, the friction member 25b is formed of an elastic material so that the downstream apex 25d can be displaced and is fixed to the inclined portion 25a.

  Therefore, there is no troublesome dimension management of the gap between the primary separation part and the secondary separation part, which is necessary in the prior art, and the dimension management of the overlap amount D2 between the transport roller 22 and the friction member 25b becomes easy. When the medium P having poor separability such as gloss paper or OHP paper is fed, the medium P can be stably separated.

(Configuration of Example 2)
The overall configuration of the image forming apparatus 1 according to the second embodiment of the present invention is the same as that of FIG. In the second embodiment, the configuration of a paper feeding unit which is a paper feeding device as a medium supply device is different from that in the first embodiment.

  FIG. 7 is an enlarged side view showing the vicinity of the sheet feeding unit 20A according to the second embodiment of the present invention. Elements common to those in FIG. It is attached.

  The sheet feeding unit 20A according to the second embodiment is different from the sheet feeding roller 21 similar to the sheet feeding unit 20 according to the first embodiment and the primary separation unit 25 with a different configuration from the primary separation unit 25 in the sheet feeding unit 20 according to the first embodiment. 25A, and a semi-retarded secondary separation unit 24 including a conveyance roller 22 and a separation roller 23 that are in pressure contact with each other by a predetermined pressure contact force as in the paper supply unit 20 of the first embodiment. In the semi-secondary secondary separation unit 24, the transport roller 22 is driven by a drive system (not shown), but the separation roller 23 is not driven by a drive system.

  The primary separation unit 25A of the second embodiment includes a fixing member 27 that is detachably fixed to the conveyance guide 26, and a sliding member 28 that is slidably engaged is provided on the fixing member 27. ing. As in the first embodiment, the sliding member 28 is provided with an inclined portion 25a extending from the paper supply roller 21 in the feeding direction and obliquely upward. As in the first embodiment, the friction member 25b is fixed to the surface of the inclined portion 25a only on the upstream side with the double-sided tape 25c. As in the first embodiment, the friction member 25b is disposed on both sides of the conveying roller 22 and the separation roller 23 at a distance D3 as shown in FIG. Unlike the first embodiment, the friction member 25b fixed to the inclined portion 25a has a position of the downstream apex 25d that is variable in the vertical direction (that is, the vertical direction), and has an overlapping amount D2 with the conveying roller 22. It is the structure which has the mechanism to adjust in steps. Other configurations are the same as those of the first embodiment.

FIG. 8 is an enlarged side view showing the vicinity of the primary separation portion 25A in FIG.
The sliding member 28 is rotatably engaged by a lock member 29 and a shaft 30, and the shaft 30 is slidably engaged with the fixed member 27. A plate spring 31 made of metal or the like is fixed to the sliding member 28. The leaf spring 31 urges the lock member 29 in the horizontal direction x of the arrow, and the protrusion 29 a of the lock member 29 is engaged with one of the two grooves 27 a and 27 b of the fixing member 27. The position of the sliding member 28 in the vertical direction y1 of the arrow is regulated and fixed.

  FIG. 8 shows a state where the sliding member 28 is fixed to the vertically upward direction y1 side. This state is a state where the conveying roller 22 and the downstream apex 25d of the friction member 25b overlap each other as in the first embodiment.

FIG. 9 is an enlarged side view showing the vicinity of the primary separation unit 25A after the operation of FIG.
FIG. 9 shows a state where the sliding member 28 is fixed to the vertical downward direction y2 side of the arrow. This state is a state adjusted to a position where a gap is provided between the conveying roller 22 and the downstream vertex 25d of the friction member 25b.

(Feeding operation of Example 2)
FIG. 10 is an enlarged side view showing the operation in the vicinity of the sheet feeding unit 20A in FIG.
The sheet feeding operation in the state of the primary separation unit 25A shown in FIGS. 7 and 8 is the same as that in the first embodiment.

The sheet feeding operation in the state of the primary separation unit 25A shown in FIGS. 9 and 10 is as follows.
As in the first embodiment, the medium P stacked on the stacking plate 16 on the medium tray 15 is fed out by the paper feed roller 21. The difference from the operation of the first embodiment is that, as shown in FIG. 10, the fed medium P first comes into contact with the friction member 25b of the primary separation unit 25A. In this state, the medium P that has entered the displaceable region on the downstream side of the friction member 25 b and has been transported may be transported to the transport roller 22. Further, the conveyance roller 22 and the friction member 25 b are conveyed to the separation roller 23 in the secondary separation unit 24 because a gap G through which the medium P passes is provided.

  When only one medium P is fed to the separation roller 23, the separation roller 23 is rotated around the medium P in the feeding direction by the conveyance force of the conveyance roller 22. Therefore, the medium P is transported to the downstream paper feed detection sensor 37 shown in FIG.

  When two sheets of the first medium Pl from the top and the second medium P2 from the top are fed to the separation roller 23, the driving force of the transport roller 22 and the medium P1 that contacts the transport roller 22 The medium conveying force Fr generated by the frictional force μr with the conveying roller 22 and the braking force Ft that causes the separation roller 23 to stop the medium P2 contacting the separation roller 23 by the torque limiter 27 in FIG. The frictional force Fμp between the medium P1 in contact with the roller 22 and the medium P2 in contact with the separation roller 23 is sufficiently larger (Fr, Ft) >> Fμp). Therefore, only the medium P1 that contacts the transport roller 22 is transported to the downstream paper feed detection sensor 37, and the medium P2 that contacts the separation roller 23 is prevented from transporting.

  When the medium P sent from the transport roller 22 and the separation roller 23 is detected by the downstream paper feed detection sensor 37 shown in FIG. 2, as in the first embodiment, the print timing adjustment unit 38 performs the image forming unit 40. In synchronization with the image forming operation, the image is transferred onto the medium P conveyed to the image forming unit 40.

  In the second embodiment, as in the first embodiment, the secondary separation unit 24 is a semi-retarding method in which the separation roller 23 is not driven. Therefore, when there are two media P fed to the separation roller 23, a sufficient separation function can be exhibited.

(Modification of Example 2)
In the second embodiment, the same modifications as in the modifications (a) and (b) of the first embodiment are possible.

(Effect of Example 2)
According to the paper feeding unit 20A and the image forming apparatus 1 of the second embodiment, the sliding member 28 is slidably disposed on the primary separation unit 25A, and the friction member 25b is fixed to the sliding member 28. Thus, the position of the downstream vertex 25d of the friction member 25b is variable in the vertical direction. As a result, the amount of overlap D2 between the friction member 25b and the conveying roller 22 can be adjusted in stages, so that when the medium P such as gloss paper or OHP paper with poor separation is fed, the friction member is placed at the same position as in the first embodiment. By setting 25b, a sufficient separation function can be exhibited. Further, when a medium P having a low stiffness such as thin paper having relatively good separation properties is fed, the gap G is set to a position where a gap G is formed between the conveying roller 22 and the downstream vertex 25d of the friction member 25b. The amount of displacement of the member 25b is reduced. As a result, it is possible to reduce the load during conveyance to the medium P, and to obtain an effect of not causing damage such as wrinkles and scratches.

(Configuration of Example 3)
The overall configuration of the image forming apparatus 1 according to the third embodiment of the present invention is the same as that of FIG. In the third embodiment, the configuration of a paper feeding unit which is a paper feeding device as a medium supply device is different from those in the first and second embodiments.

  FIG. 11 is an enlarged side view showing the vicinity of the paper feed unit 20B in the third embodiment of the present invention, and FIG. 12 is an enlarged side view showing the vicinity of the primary separation unit 25B in FIG. In FIGS. 11 and 12, elements common to those in FIGS. 1 and 4 showing the vicinity of the sheet feeding unit of the first embodiment are denoted by common reference numerals.

  As illustrated in FIG. 11, the sheet feeding unit 20 </ b> B of the third embodiment includes a sheet feeding roller 21 similar to the sheet feeding unit 20 of the first embodiment, and a primary separation unit 25 in the sheet feeding unit 20 of the first embodiment. A primary separation unit 25B having a different configuration, and a semi-retarded secondary separation unit 24 composed of a conveying roller 22 and a separation roller 23 that are pressed against each other by a predetermined pressure as in the paper feeding unit 20 of the first embodiment. Have. In the semi-secondary secondary separation unit 24, the transport roller 22 is driven by a drive system (not shown), but the separation roller 23 is not driven by a drive system.

  The primary separation unit 25 </ b> B includes a fixing member 32 that is detachably fixed to the conveyance guide 26. As shown in FIG. 12, the upper end portion of the fixing member 32 is provided with a rotating member 34 capable of rotationally displacing the downstream side with an upstream shaft 33 as a fulcrum. The rotating member 34 corresponds to the inclined portion 25a of the first embodiment extending from the paper supply roller 21 in the feeding direction and obliquely upward.

  Similar to the first embodiment, the friction member 25b is fixed to the entire upper surface, which is a flat surface of the rotating member 34, with a double-sided tape 25c. The bottom surface side of the rotating member 34 is urged by a spring 35 made of metal or the like in a direction extending in the feeding direction and obliquely upward from the paper feeding roller 21, and the position of the downstream vertex 25d of the friction member 25b is set. It is configured to regulate. As shown in FIG. 3, the friction member 25b is disposed on both sides of the conveying roller 22 and the separation roller 23 at a position separated by a distance D3.

(Feeding Operation of Example 3)
13 and 14 are enlarged side views showing the operation in the vicinity of the paper feeding unit 20B in FIG. 11, similarly to FIG.

  The sheet feeding operation in the state of the primary separation unit 25B shown in FIGS. 11 and 12 is the same as that of the first embodiment. That is, the medium P stacked on the stacking plate 16 on the medium tray 15 is fed out by the paper feed roller 21. The fed medium P first strikes the friction member 25b of the primary separation unit 25B. The front end portions of the plurality of media P are wound along the inclined surface of the friction member 25b due to the frictional force and inclination of the friction member 25b.

  However, in FIG. 13, the medium P with high friction between the media and poor separation may rush into the intersection 25e between the conveying roller 22 and the friction member 25b in a state where the medium P is multiplexed and sent on the slope of the friction member 25b. . In FIG. 14, the uppermost P1 (that is, the first sheet from the top) of the multiplex feeding medium P that has entered the intersection 25e is the medium P1 that is in contact with the driving force of the conveying roller 22, the conveying roller 22, and the conveying roller 22. Is fed downstream by the medium conveying force Fr in the direction of the arrow generated by the frictional force μr. As a result, the friction member 25b attached to the rotating member 34 has the downstream vertex 25d displaced to the position 25d-1 on the separation roller 23 side with the shaft 33 as a fulcrum, thereby enabling the conveyance of the medium P1.

  Also, due to the reaction force generated by the displacement of the spring 35, the braking force Ft in the direction of the arrow for stopping the medium P2 contacting the friction member 25b increases, and the medium conveying force Fr and the braking force Ft are conveyed. The frictional force Fμp in the direction of the arrow between the medium P1 in contact with the roller 22 and the medium P2 in contact with the friction member 25b is sufficiently larger (Fr, Ft >> Fμp). Therefore, only the medium P1 that contacts the transport roller 22 is transported to the separation roller 23 on the downstream side, and the medium P2 that contacts the friction member 25b is prevented from transporting. The subsequent operations are the same as those in the first embodiment.

(Modification of Example 3)
In the third embodiment, the same modifications as the modifications (a) and (b) of the first embodiment are possible.

(Effect of Example 3)
According to the sheet feeding unit 20B and the image forming apparatus 1 of the third embodiment, the rotation member 34 is provided in the primary separation unit 25B, and the rotation member 34 is biased by the spring 35. Thus, the effect of stabilizing the reaction force on the first medium Pl and the second medium P2 from the top can be obtained.

(Other variations of Examples 1 to 3)
The present invention is not limited to the first to third embodiments, and various other usage forms and modifications are possible. For example, the following forms (1) and (2) are used as the usage form and the modification examples.

  (1) In the description of the first to third embodiments, an electrophotographic printer has been described as an example of the image forming apparatus 1. However, another apparatus (for example, a multi-purpose apparatus having a sheet feeding apparatus that feeds a medium such as a cut sheet). The present invention can also be applied to functional printing apparatuses, facsimile machines, copiers, and the like. The present invention can also be applied to a document feeder of an image reading device.

  (2) The image forming method of the image forming unit 40 is not particularly limited, and can be applied not only to the electrophotographic method but also to various methods such as an ink jet method.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 15 Medium tray 20, 20A, 20B Paper feed part 21 Paper feed roller 22 Conveyance roller 23 Separation roller 24 Secondary separation part 25, 25A, 25B Primary separation part 25a Inclination part 25b Friction member 28 Sliding member 34 Rotating member 40 Image forming unit 50 Fixing unit

Claims (6)

A feed roller for feeding a plurality of stacked media;
The Rukoto given transport load to the plurality of media fed by the feeding roller, a primary separation unit for separating the plurality of media,
When the plurality of medium supplied is abutted by passing through the primary separation unit, as well as have a transport roller and the separation roller for conveying the plurality of media to the downstream side in the conveying direction, said plurality A secondary separation unit for further separating a sheet of media;
Equipped with a,
The primary separation unit is disposed on both sides in the width direction of the transport roller and at positions spaced apart from the transport roller, and extends obliquely upward from the feed roller toward the feed direction. And a friction member having elasticity for giving the conveyance load to the plurality of media to be fed,
The upstream portion in the conveyance direction of the friction member is fixed on the inclined portion,
A portion of the friction member on the downstream side in the conveyance direction is disposed at a position overlapping the conveyance roller when the conveyance roller is viewed from the axial direction, and protrudes from the inclined portion . when the plurality of media according to driving Ru is fed to the secondary separation unit by passing through the primary separating section, is displaceable by Rukoto pushed down by the plurality of media,
An end of the inclined portion on the downstream side in the conveyance direction is positioned above a straight line connecting a pressure contact between the feeding roller and the plurality of media and a pressure contact between the conveyance roller and the separation roller. A medium supply device. The primary separator is
The medium supply device according to claim 1, further comprising: a position adjusting mechanism capable of varying an overlapping amount of a downstream side portion of the friction member with respect to the conveyance roller. The primary separator is
Have variably position adjustment Organization of overlap of the downstream side portion of the friction member for the previous SL conveying roller,
In the position adjustment mechanism,
The medium supply apparatus according to claim 1, wherein a sliding member that moves the inclined portion in the vertical direction is provided. The downstream side portion of the front Symbol friction member,
It said friction the transport direction upstream portion medium supply apparatus according to claim 1 or 2, wherein the as a fulcrum are enabled rotation displaced out of the member. The plurality of media supplied from the primary separator to the secondary separator are:
After contacting the upstream portion in the transport direction of the friction member fixed on the inclined portion, contact the downstream portion in the transport direction of the friction member protruding from the inclined portion.
The medium supply device according to claim 1. The medium supply device according to any one of claims 1 to 5 ,
Image forming means for forming an image on the fed media body from the medium supply device,
An image forming apparatus comprising:

Images