JP5651796B2 - Paper feeding device and image forming apparatus having the same - Google Patents

Description

  INDUSTRIAL APPLICABILITY The present invention is a sheet feeding device used for an image forming apparatus such as a printer, a copier, a facsimile machine, or a multifunction machine having these functions in combination, and an image forming apparatus having the same, particularly suitable for downsizing. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet feeder provided with a sheet blowing mechanism using hot air assist and an image forming apparatus including the sheet feeder.

  Conventionally, in image forming apparatuses such as printers, copiers, and facsimiles, sheet-like recording media that can be continuously fed are usually limited to high-quality paper and cut sheets such as plain paper designated by the copier manufacturer. It was used. Such a cut sheet such as high-quality paper or plain paper has a relatively low surface smoothness and thus has a relatively low adhesion between sheets. Therefore, when feeding cut sheets one by one from a sheet stacking unit such as a paper feed tray, it is relatively easy to prevent multiple feeds in which a plurality of cut sheets are supplied in close contact. In addition, when these cut sheets are used, even if double feeding occurs, it is possible to send out the cut sheets one by one relatively well by providing a separation roller, a separation pad or a separation claw. It was.

  However, in recent years, sheet-shaped recording media have been diversified, and only sheets with low surface smoothness such as high-quality paper and plain paper are not used. In particular, with the development of colorization technology for image forming devices, coated paper with increased whiteness and glossiness (a coating color, a type of paint, is applied to both sides or one side of the sheet for the purpose of improving printability) Those having high surface smoothness such as a coated composite sheet) have been used. That is, in recent years, not only high-quality paper and plain paper, but also the above-mentioned coated paper, as well as film sheets, tracing paper, and the like, there is an increasing demand for conveyance by the same model. Here, coated paper, film sheets, tracing paper, etc. have strong adhesion between the sheets, so it is difficult to prevent double feeding of sheets, and special measures are required for paper feeding (sheet feeding). It becomes.

  In addition, the sheet bundle placed on the sheet stacking unit is likely to contain a lot of moisture because its upper surface and outer peripheral part are in contact with the outside air. That is, while the upper surface and side surface of the sheet bundle swell due to moisture absorption, the degree of swelling is lower because the inside of the sheet bundle has less moisture than the upper surface and side surface. As a result, the inner space (space between sheets) of the sheet bundle becomes negative pressure, and the sheets are in close contact with each other.

  Therefore, in a large-sized copying machine or the like, a mechanism that blows warm air on the side surface of the sheet bundle in order to release the adhesion between the sheets and spread the sheet bundle prior to feeding (hereinafter referred to as “lateral warm air assist”). A paper feeding device having the above is employed.

  For example, Patent Document 1 discloses a technique for improving the drying efficiency of a sheet by appropriately adjusting the humidity of the lateral warm air blown to the side surface of the sheet bundle in the sheet rolling method using the lateral warm air assist.

JP 2001-48366 A Japanese Patent Laid-Open No. 2003-150024 JP 2006-264917 A JP 2007-62894 A Japanese Utility Model Publication No. 7-12359

  However, with the conventional sheet-rolling technology using the above-mentioned lateral hot air assist, it is difficult for hot air to reach the area away from the hot air outlet, so the hot air is blown around the outer periphery of the sheet with particularly strong adhesion. It is not easy. That is, in the case of using the conventional lateral hot air assist, a favorable wind effect cannot be obtained unless a large-sized one is used as the configuration of the hot air blowing means, heater means, drive source, and the like required for this. For this reason, the conventional sheet-rolling technique using the side warm air assist has been limited to application to a relatively large feeding deck having about 2000 to 4000 sheets.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a sheet feeding device provided with a sheet blowing mechanism by hot air assist that can be installed even in a small space, and an image forming apparatus provided with the sheet feeding device.

A sheet feeding device according to one aspect of the present invention is a sheet feeding device capable of continuously feeding a sheet-like recording medium to a predetermined conveyance path, and an apparatus main body that forms at least a part of the conveyance path; Including a sheet storage unit that stores a sheet bundle composed of a plurality of sheet-like recording media, and a paper feed cassette that can be pulled out from the apparatus main body, and an upstream end in a paper feed direction in the sheet storage unit is freely rotatable The sheet stacking plate supported by the sheet bundle, a pickup roller that abuts on the upper surface of the sheet bundle and feeds the uppermost sheet-like recording medium of the sheet bundle, and the sheet mounting plate is the first. A retracted position that has been lowered to the bottom, a sheet feeding position where the sheet placement plate is lifted from the retracted position, and an upper surface of the sheet bundle is in contact with the pickup roller, and a position between the retracted position and the sheet feeding position. And the sheet bundle Upper surface between the spaced position spaced apart from the pick-up roller, a lifting mechanism for displacing the seat mounting plate, in the vertical cross section along the paper feed direction, those in the pick-up roller in the sheet feeding position On the side surface parallel to the sheet feeding direction of the sheet bundle disposed in the sheet storage portion so as to be opposed to the sheet bundle so as to include a part of the sheet bundle at the separation position and the upper surface of the sheet bundle in contact therewith A first hot air mechanism that blows warm air; and a control unit that controls the up-and-down drive of the up-and-down mechanism, and the control unit sets a period during which a plurality of sheet-like recording media are continuously fed by the pickup roller. During the hot air blowing operation by the first hot air mechanism, the sheet placement plate disposed at the paper feeding position is lowered to the separation position, and then again the paper feeding position. As increase, controls the lifting drive of the lifting mechanism, the first warm air mechanism is characterized in that provided in the apparatus main body.

  According to said structure, it is supported so that it may raise / lower within the said sheet storage part, the sheet | seat mounting plate which stack | stacks the said sheet-like recording medium, the said sheet | seat mounting plate is raised / lowered, and the said sheet | seat mounting plate is fed. An elevation mechanism that displaces between the position and the retracted position; a sheet loading position between a sheet feeding position where the upper surface of the sheet bundle contacts the pickup roller; and a separation position where the upper surface of the sheet bundle is separated from the pickup roller. An elevating mechanism for displacing the placing plate, and a first hot air mechanism for blowing hot air to the side surface parallel to the sheet feeding direction of the sheet bundle stored in the sheet storage unit.

  In a small paper feeder using the lifting mechanism as described above, it is difficult to mount a hot air blowing mechanism using a large hot air mechanism. Therefore, there is a need for a hot air mechanism that has high sheet-rolling efficiency and can efficiently roll the sheet-like recording medium stored in the sheet storage portion prior to feeding even with a small amount of hot air.

  Therefore, according to the above-described configuration of the present invention, the controller includes a control unit that controls the raising / lowering drive of the elevation mechanism, and the control unit is a side surface parallel to the sheet feeding direction of the sheet bundle by the first hot air mechanism. While the warm air blowing operation is being performed, the raising / lowering drive of the raising / lowering mechanism is controlled so that the sheet placing plate is displaced between the sheet feeding position and the separation position.

  Normally, when the sheet placing plate is driven up to a sheet feeding position where the upper surface of the sheet bundle contacts the pickup roller, and the sheet feeding operation is started, the sheet placing plate is fixed at the sheet feeding position. The sheets are sequentially fed from the uppermost sheet-like recording medium. However, at this sheet feeding position, the upper surface of the sheet bundle is pressed by the pickup roller, and even if the lateral warm air is continuously applied to the side surface of the sheet bundle at the sheet feeding position, the gap between the sheets is small and warm. The wind is difficult to enter. Therefore, the present invention provides the lifting mechanism so that the sheet placing plate is displaced between the sheet feeding position and the separation position while the warm air blowing operation by the first warm air mechanism is performed. The elevator drive is controlled.

  That is, the control unit lowers the sheet placing plate, which has been raised to the sheet feeding position where the upper surface of the sheet bundle contacts the pickup roller, to the separated position separated from the pickup roller, and then again feeds the sheet. The raising / lowering drive of the raising / lowering mechanism is controlled so that it may raise to a position. As described above, the control unit performs the separation operation of displacing the sheet placing plate between the sheet feeding position and the separation position, while moving the sheet from the first hot air mechanism to the side surface parallel to the sheet bundle feeding direction. It is controlled to blow warm air.

  Since the gap between the sheets of the sheet bundle can be widened by the above separation operation, even hot air applied in a spot manner can be easily blown to a place away from the hot air outlet. As a result, it is possible to realize a lateral warm air mechanism (first warm air mechanism) that has higher sheet rolling efficiency than a conventional large-sized lateral warm air assist, and thus it is possible to reduce the size of the entire sheet feeding device. .

  In the above configuration, the first hot air mechanism is disposed opposite to the sheet feeding cassette on the upstream side of the pickup roller in the sheet feeding direction, and sucks air from the inlet and the inlet. An air passage that guides the air in the sheet feeding direction, a heater that is disposed in the air passage and heats the air, and the air that is heated by the heater is stored in the sheet storage portion. And a blower outlet that blows out toward the side surface parallel to the sheet feeding direction and at an angle to the upstream side of the sheet feeding direction with respect to the width direction of the sheet bundle.

  In the above configuration, a pair of conveyance rollers provided on the downstream side of the pickup roller in the paper feeding direction and sandwiching and conveying the sheet-like recording medium fed by the pickup roller, and the sheet-like recording sent by the pickup roller A leading edge detecting unit that detects a state in which a leading end portion of the medium in the paper feeding direction passes between the pair of conveying rollers, and the control unit detects the state when the leading edge detecting unit detects the state. The elevating mechanism may be controlled so that the sheet placing plate starts to descend from the paper feeding position to the separation position.

  In the above configuration, the control unit may further include a rear end detection unit that detects a state in which a rear end portion in the sheet feeding direction of the sheet-like recording medium fed by the pickup roller passes between the pair of transport rollers. The lift mechanism may be controlled such that when the trailing edge detection unit detects the state, the sheet placing plate starts to rise from the separation position to the sheet feeding position.

  An image forming apparatus according to another aspect of the present invention includes the sheet feeding device having the above-described configuration and an image forming unit that forms an image on a sheet-like recording medium fed from the sheet feeding device. It is characterized by.

  According to the above configuration, a sheet warming mechanism using warm air can be realized as a sheet warming mechanism with higher sheet rolling efficiency than a conventional large sheet warm air assist. Can be realized. As a result, it is possible to reduce the size of the entire image forming apparatus having a sheet feeding device having a sheet winding mechanism using warm air.

  According to the present invention, it is possible to provide a sheet feeding device equipped with a sheet blowing mechanism by hot air assist that can be installed even in a small space and an image forming apparatus provided with the sheet winding efficiency by improving the sheet blowing efficiency by warm air.

1 is a perspective view illustrating an appearance of a printer including a paper feeding device according to an embodiment of the present invention. FIG. 2 is a cross-sectional view illustrating an internal configuration of the printer illustrated in FIG. 1. It is sectional drawing which shows the structure of the paper feeding apparatus which concerns on one Embodiment of this invention. FIG. 4 is a perspective view illustrating a state in which a sheet feeding cassette in the sheet feeding device illustrated in FIG. 3 is pulled out from a sheet feeding device body. It is explanatory drawing which shows the position detection sensor mounted in the paper feeder shown in FIG. It is explanatory drawing explaining the structure of the paper feeder which concerns on one Embodiment of this invention. It is sectional drawing of the horizontal direction which shows the principal part of the side warm air mechanism mounted in the paper feeder shown in FIG. It is explanatory drawing which shows the warm air blowing direction of the horizontal warm air mechanism in the paper feeder shown in FIG. It is explanatory drawing for demonstrating the warm air blowing state of the side warm air mechanism in the paper feeder shown in FIG. FIG. 4 is a vertical cross-sectional view illustrating a main part configuration of an upper warm air mechanism mounted on the sheet feeding device illustrated in FIG. 3. FIG. 7 is a perspective view of a paper feed cassette for explaining a direction in which the lateral warm air and the upper warm air are blown in the paper feeder shown in FIG. 6. It is explanatory drawing which shows the blowing direction of side warm air and top warm air in the paper feeder shown in FIG. It is a functional block diagram of the control part which controls the warm air blowing operation | movement accompanying the separation operation | movement which concerns on one Embodiment of this invention. It is a flowchart which shows the control process by the control part shown in FIG. It is a functional block diagram of the control part which controls the warm air blowing operation | movement accompanying the separation operation | movement which concerns on other embodiment of this invention. It is a flowchart which shows the control process by the control part shown in FIG. It is a principal part longitudinal cross-sectional view of the paper feed unit which concerns on one Embodiment of this invention. It is a principal part longitudinal cross-sectional view of the paper feed unit which concerns on one Embodiment of this invention. It is a principal part longitudinal cross-sectional view of the paper feed unit which concerns on one Embodiment of this invention.

  Hereinafter, the best embodiment of the present invention will be described in detail with reference to the drawings. In addition, in each drawing, the member etc. which attached | subjected the same code | symbol are the same structures, The duplication description about these shall be abbreviate | omitted suitably. Moreover, in each drawing, members and the like that are not necessary for the description are omitted as appropriate.

<First Embodiment>
With reference to FIG. 1 and FIG. 2, an image forming apparatus including a sheet feeding device according to an embodiment of the present invention will be described.

  FIG. 1 is a perspective view illustrating an appearance of an image forming apparatus including a sheet feeding device according to a first embodiment of the present invention. FIG. 2 is a cross-sectional view showing the internal structure of the image forming apparatus.

  As shown in FIG. 1, a color printer 1 as an image forming apparatus according to an embodiment of the present invention includes a printer main body 200 connected directly to a personal computer (PC) (not shown) or the like via a LAN, A sheet supply unit 100 is provided below the printer main body 200 and configured to store sheets P of various sizes according to the sizes. The color printer 1 also includes other components provided in a general color printer, such as a control circuit that controls the operation of the color printer X.

  As shown in FIG. 2, the printer body 200 includes toner containers 900Y, 900M, 900C, and 900K, an intermediate transfer unit 92, an image forming unit 93, an exposure unit 94, a sheet supply unit 100, a fixing unit 97, a paper discharge unit 96, An apparatus main body casing 90, a top cover 911, and a front cover 912 are provided.

  The image forming unit 93 includes a yellow toner container 900Y, a magenta toner container 900M, a cyan toner container 900C, and a black toner container 900K, and developing devices 10Y, 10M, and 10C corresponding to the respective colors of YMCK. 10K.

  The image forming unit 93 is further provided with a photoreceptor drum 17 (a photoreceptor on which a latent image is formed by an electrophotographic method) that carries toner images of respective colors. As the photoreceptor drum 17, a photoreceptor drum using an amorphous silicon (a-Si) material can be used. Each photosensitive drum 17 is supplied with yellow, magenta, cyan, and black toner from the corresponding toner containers 900Y, 900M, 900C, and 900K.

  Note that the image forming unit 93 of the present embodiment is configured to form a full-color image as described above, but is not limited thereto, and is configured to form a monochrome image or a color image that is not full-color. It may be.

  Around the photosensitive drum 17, a charger 16, a developing device 10 (10Y, 10M, 10C, 10K), a transfer device (transfer roller) 19, a cleaning device 18 and the like are arranged. The charger 16 uniformly charges the surface of the photosensitive drum 17. The surface of the photosensitive drum 17 after charging is exposed by the exposure unit 94 to form an electrostatic latent image. The developing devices 10Y, 10M, 10C, and 10K develop the electrostatic latent images formed on the respective photosensitive drums 17 using the toners of the respective colors supplied from the toner containers 900Y, 900M, 900C, and 900K, respectively ( Visualization). The transfer roller 19 forms a nip portion with the photosensitive drum 17 across the intermediate transfer belt 921, and primarily transfers the toner image on the photosensitive drum 17 onto the intermediate transfer belt 921. The cleaning device 18 cleans the peripheral surface of the photosensitive drum 17 after the toner image is transferred.

  Each of the developing devices 10Y, 10M, 10C, and 10K includes a housing 20, in which a two-component developer having a magnetic carrier and toner is stored. In the housing 20, two agitation rollers 11 and 12 (developer agitation members) are rotatably arranged in parallel near the bottom of the housing with the longitudinal direction as an axial direction.

  A developer circulation path is set on the inner bottom surface of the housing 20, and the stirring rollers 11 and 12 are disposed in the circulation path. In the axial direction between the stirring rollers 11 and 12, a partition wall 201 erected from the bottom of the housing is provided. The partition wall 201 divides the circulation path, and the circulation path is formed so as to go around the partition wall 201. The two-component developer is charged while being stirred and conveyed by the stirring rollers 11 and 12 through this circulation path.

  The two-component developer circulates in the housing 20 while being stirred by the stirring rollers 11 and 12, the toner is charged, and the two-component developer on the stirring roller 11 is attracted to the magnetic roller 14 located on the upper side. Are transported. The sucked two-component developer forms a magnetic brush (not shown) on the magnetic roller 14, the layer thickness of which is regulated by the doctor blade 13, and the potential difference between the magnetic roller 14 and the developing roller 15 A toner layer is formed on the developing roller 15. Then, the electrostatic latent image on the photosensitive drum 17 is developed by the toner layer on the developing roller 15.

  The exposure unit 94 includes various optical system devices such as a light source, a polygon mirror, a reflection mirror, and a deflection mirror, and is based on image data on the peripheral surface of the photosensitive drum 17 provided in each of the image forming units 93. Irradiate light to form an electrostatic latent image.

  The intermediate transfer unit 92 includes an intermediate transfer belt 921, a driving roller 922, and a driven roller 923. The intermediate transfer belt 921 primarily transfers toner images from a plurality of photosensitive drums 17 in an overcoated state, and secondarily transfers the toner images to the sheet P supplied from the paper supply unit 130 at the secondary transfer unit 98. . The driving roller 922 and the driven roller 923 drive the intermediate transfer belt 921 to rotate. The driving roller 922 and the driven roller 923 are rotatably supported by a housing (not shown).

  The sheet feeding unit 130 stores a sheet bundle S composed of a plurality of sheets P on which images are formed, and is detachably attached to the housing 90.

  The fixing unit 97 performs a fixing process on the toner image on the sheet P that has been secondarily transferred from the intermediate transfer unit 92. It is discharged toward the discharge unit 96 formed in the above.

  The paper discharge unit 96 discharges the sheet P conveyed from the fixing unit 97 onto a top cover 911 serving as a paper discharge tray.

  The sheet supply unit 100 includes a plurality of stages (three stages in the present embodiment) of paper feed units (paper feeders) 130 that are detachably attached to the printer main body 200. Each stage of the sheet feeding unit 130 stores the sheet bundle S of each size, and the selected sheet feeding unit 130 is driven by a pickup roller 40 provided in the sheet feeding unit 130. The uppermost sheet P of the sheet bundle S is taken out one by one, fed out to the paper feed conveyance path 133, and introduced into the image forming unit 93.

  Each of the paper feed units 130 includes a transport mechanism that can be stacked and installed later on the lower part of the printer main body 200, so that a desired number of paper feed units 130 can be attached to the printer main body 200 at any time later. That is, by stacking a plurality of paper feed units 130 below the printer body 200, the transport mechanisms of the paper feed units 130 are coupled to each other to form a single paper feed transport path 133 extending to the printer body 200. Is done. As a result, a plurality of stacked sheet feeding units 130 can be attached later.

  In this embodiment, an example is given in which the sheet supply unit 100 is configured by a three-stage sheet feeding unit 130, but the present invention is not limited to this, and the sheet feeding unit 130 is one-stage or two-stage, or four The present invention can be similarly applied to an image forming apparatus such as a printer configured with a sheet feeding unit of more than one stage.

  Next, with reference to FIGS. 1, 3 to 5, the configuration of each sheet feeding unit (sheet feeding device) 130 installed in the sheet feeding unit 100 of the color printer 1 according to the present embodiment will be described in detail. .

  FIG. 3 is a cross-sectional view illustrating a configuration of the paper feeding device according to the present embodiment. FIG. 4 is a perspective view showing a state in which the paper feeding cassette in the paper feeding device shown in FIG. 3 is pulled out from the paper feeding device body. FIG. 5 is an explanatory diagram illustrating a position detection sensor mounted on the sheet feeding device illustrated in FIG. 3.

  As shown in FIGS. 3 and 4, the sheet feeding unit 130 has a lift plate (sheet stacking plate) for stacking a sheet bundle S composed of a plurality of sheets (sheet-like recording media) P on the inner bottom surface of the sheet storage unit 35. ) 31. The lift plate 31 is rotatably supported at its upstream end (left end portion in FIG. 3) in the sheet feeding direction by a support portion 38. That is, the lift plate 31 is rotatable in the vertical plane by the support portion 38 with the downstream end as a free end inside the sheet storage portion 35. The support portions 38 are provided on both side walls of the sheet storage portion 35 that are arranged to face each other in the width direction of the sheet P (a direction orthogonal to the sheet feeding direction).

  A sheet feeding cassette 130A of the sheet feeding unit 130 includes a width alignment cursor pair 34a and 34b for positioning the sheet P stored in the sheet storage unit 35 in the width direction, a rear end cursor 33 for aligning the rear end of the sheet P, It has. The width alignment cursor pairs 34a and 34b are provided so as to be able to reciprocate in the sheet width direction (arrow AA ′ direction in FIG. 4) along guide rails (not shown). Here, since the sheet P is sent out in the direction of arrow B, the rear end cursor 33 is provided so as to be capable of reciprocating along the guide rails 33a and 33b in parallel with the sheet conveying direction (in the direction of arrow BB 'in FIG. 4). The sheet bundle S is stored in a predetermined position in the sheet feeding unit 130 by moving the width alignment cursor pair 34a and 34b and the rear end cursor 33 in accordance with the size of the stacked sheets. The sheet feeding unit 130 includes a cassette cover 43, and the surface side (side seen from the direction of arrow C in FIG. 4) is exposed to the outside and constitutes a part of the exterior surface of the color printer 1.

  A drive shaft 36, a push-up member 32, and a drive connecting member (not shown) are provided as a lifting mechanism 30 (FIG. 13 and FIG. 15) that lifts and lowers the lift plate 31 in the lower portion of the lift plate 31 in the sheet feeding direction. Yes. Further, a receiving member (not shown) corresponding to the drive connecting member and a motor (not shown) capable of rotating forward and backward connected to the receiving member are provided on the sheet feeding unit main body 130B side. In a state where the paper feed cassette 130A is housed in the paper feed unit main body 130B, the drive connecting member of the sheet storage unit 35 on the paper feed cassette 130A side is engaged with and connected to the receiving member on the paper feed unit main body 130B side. Thereby, the power of the motor can be transmitted to the drive shaft 36. The drive shaft 36, the push-up member 32, the drive connecting member, the receiving member, and the motor constitute a lifting mechanism that displaces the lift plate 31 between the paper feeding position and the retracted position. The sheet feeding position is a position where the lift plate 31 is lifted and the upper surface of the sheet bundle S placed on the lift plate 31 comes into contact with the pickup roller 40 and can feed paper. The retracted position is a position where the lift plate 31 is lowered to the lowest position.

  In addition, as a motor which comprises the raising / lowering mechanism 30 which raises / lowers the lift board 31, the stepping motor M2 shown in FIG.13 and FIG.15, DC motor, etc. can be used, for example.

  Further, as shown in FIG. 3, the paper feed unit 130 includes a paper feed roller 41 provided on the downstream side in the transport direction of the pickup roller 40, and a separating roller 42 provided below the paper feed roller 41. Yes. Further, a transport roller 37 is provided on the downstream side in the transport direction of the pickup roller 40 and the paper feed roller 41. The paper feed roller 41 is provided along with the pickup roller 40 on the paper feed unit main body 130B side, while the separating roller 42 and the transport roller 37 are provided on the paper feed cassette 130A side. In a state where the paper feed cassette 130A is mounted on the paper feed unit main body 130B, the paper feed roller 41 and the separating roller 42 come into contact with each other.

  The paper feed roller 41 feeds the sheet P taken out by the pickup roller 40 to the transport roller 37. The paper feed roller 41 rotates in a direction in which the sheet P can be conveyed downstream, whereas the separating roller 42 rotates in a direction in which the sheet P is sent back upstream. Even if the sheets P picked up by the conveyance pickup roller 40 are overlapped, the separation roller 42 can prevent the sheet P other than the uppermost sheet P from being fed in the direction of the conveyance roller 37. Only the sheet feed roller 41 is transported to the transport roller 37. The transport roller 37 transports the sheet P to the paper feed transport path 133 (see FIG. 2).

  Further, as shown in FIGS. 5A and 5B, the sheet feeding unit 130 detects that the uppermost sheet P of the sheet bundle S placed on the lift plate 31 is at the sheet feeding position. A position detection sensor 39 is provided. The position detection sensor 39 includes a light shielding member 39A and an optical sensor 39B. The optical sensor 39B includes a light emitting element fixedly provided near the pickup roller 40 and a light receiving element that receives light emitted from the light emitting element. On the other hand, the light shielding member 39 </ b> A is provided on the support member 50 of the pickup roller 40. Further, the support member 50 is provided so as to be rotatable about the rotation axis of the paper feed roller 41. As a result, when the upper surface of the sheet bundle S placed on the lift plate 31 moves to the sheet feeding position shown in FIG. 5B by the lift of the lift plate 31, the pickup roller 40 pushes up to the uppermost sheet P. Then, it rotates around the rotation axis of the paper feed roller 41 and is displaced slightly upward. At this time, the light shielding member 39A is lifted upward in conjunction with the pickup roller 40, the light path of the optical sensor 39B is shielded, and it can be detected that the upper surface of the sheet bundle S is in the paper feeding position.

  In the sheet feeding unit 130 configured as described above, the push-up member 32 pushes up the downstream end side of the lift plate 31 while engaging the bottom surface of the lift plate 31 by the operation of the motor. As a result, the upper surface of the sheet bundle S stacked on the lift plate 31 is displaced to the paper feed position where it abuts on the pickup roller 40 provided above the paper feed cassette 130A.

  At this time, as shown in FIG. 5B, when the position detection sensor 39 detects the displacement of the pickup roller 40 to the paper feeding position, the driving of the motor is stopped. When the position detection sensor 39 is not detected due to the decrease of the sheet P during feeding, the motor is operated to lift the sheet bundle S to the feeding position.

  In the present embodiment, the detected portion (light shielding member 39A) is provided on the support member 50 of the pickup roller 40, but the present invention is not limited to this. For example, the upper surface of the sheet bundle S near the pickup roller 40 may be directly detected, or a detection mechanism other than the optical sensor may be used.

  As shown in FIGS. 2, 3, and 6 to 9, the sheet feeding unit 130 according to the present embodiment includes a lateral warm air mechanism (first warm air mechanism) 150 as a sheet blowing mechanism by blowing warm air. Yes.

  FIG. 6 is an explanatory diagram illustrating the configuration of the sheet feeding device according to the present embodiment. FIG. 7 is a horizontal cross-sectional view showing a main part of the horizontal warm air mechanism mounted on the paper feeding device according to the present embodiment. FIG. 8 is an explanatory diagram showing the hot air blowing direction of the horizontal hot air mechanism according to the present embodiment. FIG. 9 is an explanatory diagram for explaining a hot air blowing state of the horizontal hot air mechanism according to the present embodiment.

  The horizontal warm air mechanism 150 is provided on the paper feed unit main body 130B side. As shown in FIG. 6, a top plate 56 is formed on the upper surface of the sheet feeding unit main body 130 </ b> B where the side warm air mechanism 150 and the later-described upper warm air mechanism (second warm air mechanism) 140 are not formed. The sheet storage space is closed with the top plate 56.

  As shown in FIG. 6, the horizontal hot air mechanism 150 is provided along one side surface of the paper feeding cassette 130 </ b> A in the paper feeding direction. Further, as shown in FIG. 7, the lateral warm air mechanism 150 includes a first fan (air blowing unit) 151 and a first heater (heating unit) 152 provided in the lateral warm air chamber 153 (air blowing unit). ing.

  As shown in FIG. 7, the horizontal hot air mechanism 150 is configured to suck in air in the paper feed unit 130 from a first suction port (air blowing unit) 154 provided in the paper feed unit 130. When the air in the lateral warm air chamber 153 moves toward the first heater 152 due to the rotation of the first fan 151, the air in the sheet feeding unit 130 is taken into the lateral warm air chamber 153 from the first suction port 154. The air that has moved to the first heater 152 side is heated by the first heater 152 and blown out from the first hot air outlet 155 toward the side surface of the sheet bundle S.

  Here, as shown in FIG. 3, the first hot air outlet 155 of the horizontal hot air mechanism 150 that blows hot air to the side surface of the sheet bundle S at the sheet feeding position is connected to the pickup roller 40 in a vertical section in the sheet conveying direction. Oriented at a point N where the upper surface of the sheet bundle S abuts. As a result, the hot air can be concentrated on the side surface of the sheet bundle S that is exactly taken out by the pickup roller 40, and the hot air can be efficiently blown between the sheets of the portion. Therefore, even if the horizontal hot air mechanism 150 is not large, the sheet bundle S can be efficiently spread prior to paper feeding.

  Further, as shown in FIG. 8, the first hot air outlet 155 sends the warm air straight (in parallel) in the width direction of the sheet bundle S (the direction of arrow C in FIG. 8, which is a direction orthogonal to the sheet feeding direction). Instead of blowing out, as shown by an arrow B in FIG. 8, the hot air is blown out at an angle to the sheet center direction side with respect to the width direction of the sheet bundle S. The reason is as follows.

  When hot air is blown out in the direction of arrow C in FIG. 8, as shown in FIG. 9B, the hot air escapes from the side surface of the sheet bundle S to the downstream side in the sheet feeding direction. It is difficult to reach the back of S, and the efficiency of blowing by the side warm air is low. Therefore, the horizontal hot air mechanism 150 according to the present embodiment forms a first hot air outlet 155 that blows the hot air toward the center side of the sheet bundle S to be fed, as indicated by an arrow B in FIG. ing. As a result, the hot air blown from the first hot air outlet 155 can be confined between the sheets of the sheet bundle S as shown in FIG. That is, when the hot air is blown toward the center side of the sheet bundle S, the upstream and downstream sides in the sheet feeding direction hang down with the weight of the sheet P and the lid is closed, and the hot air escapes to the outside. A wide range of hot air can be blown into the back of the sheet without any problems. As a result, the sheet bundle S can be efficiently spread prior to feeding even with the same amount of hot air.

  As shown in FIGS. 2, 3, 6, and 10, the sheet feeding unit 130 according to the present embodiment includes an upper warm air mechanism 140 as a sheet blowing mechanism by blowing hot air in addition to the lateral warm air mechanism 150. I have.

  FIG. 10 is a vertical cross-sectional view illustrating a configuration of a main part of the upper warm air mechanism mounted on the paper feeding device according to the present embodiment.

  The upper warm air mechanism 140 is provided on the side of the paper feed unit main body 130 </ b> B, similarly to the above-described horizontal warm air mechanism 150. As shown in FIG. 10, the upper warm air mechanism 140 takes in air from the second suction port (air blowing unit) 144 and is provided above the upper surface of the sheet bundle S stored in the sheet storage unit 35. The hot air is blown out from the hot air outlet (air blowing unit) 145 toward the upper surface of the sheet bundle S.

  Further, the upper warm air mechanism 140 includes a second fan (air blowing unit) 141 and a second heater (heating unit) 142 in the upper warm air chamber (air blowing unit) 143. The second suction port 144 is provided above the second fan 141 on the upper surface of the upper warm air chamber 143. That is, the air in the upper warm air chamber 143 moves to the second heater 142 side by the rotation of the second fan 141, and outside air is taken into the upper warm air chamber 143 from the second suction port 144. The air that has moved to the second heater 142 side is heated by the second heater 142 and is blown out from the second hot air outlet 145 provided on the lower surface of the upper hot air chamber 143 toward the upper surface of the sheet bundle S. It has become. The second warm air outlet 145 is formed on the downstream side in the sheet feeding direction in the upper warm air mechanism 140 in a state where the upper warm air mechanism 140 is mounted on the sheet feeding unit 130.

  In the above configuration, when a predetermined paper feeding unit 130 is selected for image formation, the lift plate 31 is driven to rise, the sheet bundle S is raised toward the pickup roller 40, and the upper warm air mechanism 140 is driven. Then, warm air is blown toward the upper surface of the sheet bundle S from the second warm air outlet 145.

  Here, among the sheet bundle S, the upper surface and the outer peripheral portion of the sheet bundle S are in contact with the outside air, so that it tends to contain a lot of moisture. That is, while the upper surface and side surface of the sheet bundle S swell due to moisture absorption, the degree of swelling is relatively low because the inside of the sheet bundle S has less moisture than the upper surface and side surface. As a result, the inside of the sheet bundle S (the space between the sheets) becomes a negative pressure, causing a phenomenon that the sheets are in close contact with each other.

  However, the sheet feeding unit 130 according to the present embodiment includes the upper warm air mechanism 140, so that the relative humidity of the sheet bundle S in the sheet feeding unit 130 (the upper surface and the outer peripheral portion of the sheet bundle S and the other portions). (Relative humidity) is instantaneously reduced.

  That is, the upper hot air mechanism 140 can concentrate the hot air from the upper surface of the sheet bundle S having particularly high adhesion to the outer periphery and feed the hot air uniformly. Accordingly, the relative humidity of the sheet bundle S (the upper surface and the outer peripheral portion of the sheet bundle S and other portions is reduced by quickly reducing the moisture absorption of the upper surface and the outer peripheral portion of the sheet bundle S and eliminating the swelling state of the portion. ) Can be reduced instantaneously, and the negative pressure inside the sheet bundle S (space between sheets) can be eliminated. As a result, the adhesion between the sheets can be reduced, and the sheet bundle S can be efficiently spread prior to feeding.

  Further, as shown in FIG. 3, the upper warm air mechanism 140 according to the present embodiment is provided upstream of the pickup roller 40 in the paper feeding direction and behind the paper feeding direction in the paper feeding unit 130. . Here, since the second warm air outlet 145 is provided on the downstream side in the sheet feeding direction in the upper warm air mechanism 140 as described above, it faces the upper surface of the sheet bundle S accommodated in the sheet accommodating portion 35. The second hot air outlet 145 can be blown well. In this way, by installing the upper hot air mechanism 140 having high sheet-spreading efficiency by making effective use of the empty space in the paper feed unit 130, the sheet-rolling mechanism by hot air assist that can be applied to a small paper feeder. Can be realized.

  That is, the configuration in which the sheet bundle S placed on the lift plate 31 is raised and lowered by the cantilever raising / lowering mechanism as in the paper feeding unit (paper feeding device) 130 according to the present embodiment is used for a relatively small paper feeding device. However, when the cantilever raising / lowering mechanism is used, the sheet bundle S is lifted on the downstream side in the sheet feeding direction where the pickup roller 40 is provided, and sheet conveyance mechanisms such as the pickup roller 40 and the sheet feeding roller 41 are provided. However, since the sheet bundle S is not lifted on the upstream side in the sheet feeding direction, there is a relatively large space. If the upper warm air mechanism 140 is incorporated into the space with sufficient margin as in the present embodiment, it is not necessary to increase the outer shape of the paper feeding unit 130 in order to install the upper warm air mechanism 140. It is also suitable for a paper device.

  Next, with reference to FIG. 11 and FIG. 12, a sheet rolling effect in a configuration in which an upper warm air mechanism 140 is provided in addition to the lateral warm air mechanism 150 as a warming air assist sheet rolling mechanism will be described.

  FIG. 11 is a perspective view of the paper feed cassette for explaining the direction in which the lateral warm air and the upper warm air are blown in the paper feeder according to the present embodiment. FIG. 12 is an explanatory diagram showing the direction in which the lateral warm air and the upper warm air are blown in the paper feeder according to the present embodiment.

  As described above, the sheet feeding unit 130 according to the present embodiment blows warm air toward the upper surface of the sheet bundle S by the upper warm air mechanism 140 as shown in FIG. Therefore, warm air is blown toward the side surface of the sheet bundle S that is exactly taken out by the pickup roller 40. As a result, the sheet bundle S can be spread more efficiently prior to paper feeding than in a configuration including only the horizontal warm air mechanism 150.

  In the above configuration, when a predetermined paper feeding unit 130 is selected for image formation, the lift plate 31 is driven to rise, the sheet bundle S is raised toward the pickup roller 40, and the upper warm air mechanism 140 is driven. Then, warm air is blown toward the upper surface of the sheet bundle S from the second warm air outlet 145. Further, when the remaining sheet amount detection unit 211 detects that the upper surface of the sheet bundle S is in contact with the pickup roller 40 and the sheet bundle S has been raised to the sheet feeding position, the lateral warm air mechanism 150 is driven and the first warm air blowing is performed. Also from the outlet 155, warm air is blown toward the side surface of the sheet bundle S that is exactly located at the position taken out by the pickup roller 40.

  12 (a) to 12 (c) schematically show how the sheet bundle S can be efficiently spread by the upper warm air mechanism 140 and the lateral warm air mechanism 150. FIG.

  Initially, the upper surface and side surfaces of the sheet bundle S swell due to moisture absorption, and the inside of the sheet bundle S (the space between the sheets) becomes negative pressure, and the sheets are in close contact with each other, as shown in FIG. In addition, by the double warm air blowing by the upper warm air mechanism 140 and the lateral warm air mechanism 150, the state immediately shifts to the state shown in FIG.

  That is, the upper hot air mechanism 140 can concentrate the hot air from the upper surface of the sheet bundle S having particularly high adhesion to the outer periphery and feed the hot air uniformly. Thereby, the moisture absorption of the upper surface and outer peripheral part of the sheet bundle S is quickly reduced, and the swelling state of the part is eliminated. In particular, the upper surface of the sheet bundle S that receives the warm air directly from the upper warm air mechanism 140, and the side surface of the sheet bundle S that receives the warm air simultaneously from the upper warm air mechanism 140 and the lateral warm air mechanism 150 on the side of the lateral warm air mechanism 150. , The swelling state is eliminated first, and the state shown in FIG. 12B is obtained. Further, the state immediately shifts to the state shown in FIG. 12C (the state where the sheet bundle S is rolled).

  That is, by the warm air blowing of the upper warm air mechanism 140 and the lateral warm air mechanism 150, the swollen state of the side surface of the sheet bundle S on the opposite side to the lateral warm air mechanism 150 is instantly eliminated. The hot air passes between the sheets and goes out of the sheet bundle S, and the sheet bundle S is spread.

  In addition, in this embodiment, although the horizontal ventilation part and the heating part, and the upper ventilation part and the upper heating part were each demonstrated to the structure respectively provided in the side warm air mechanism 150 and the upper warm air mechanism 140, respectively. These members are not necessarily provided integrally. For example, one of the air blowing unit and the heating unit is provided on the paper feed cassette 130A side, and the other is provided on the paper feed unit main body 130B side. May be.

  Next, with reference to FIG. 13, FIG. 14 and FIGS. 17 to 19, the control process of the sheet rolling operation by the hot air blowing according to the present embodiment will be described.

  FIG. 13 is a functional block diagram of a control unit that controls a warm air blowing operation with a separating operation according to an embodiment of the present invention. FIG. 14 is a flowchart showing a control process by the control unit shown in FIG. 17 to 19 are longitudinal sectional views of main parts of the paper feeding unit according to this embodiment.

  As shown in the functional block diagram of FIG. 13, the sheet feeding unit 130 according to the present embodiment performs a sheet rolling operation by blowing hot air with a separating operation that displaces the lift plate 31 between the sheet feeding position and the separating position. The control part 300 which controls is provided.

  Here, the sheet feeding position is a position where the upper surface of the sheet bundle S placed on the lift plate 31 comes into contact with the pickup roller 40, and the separation position is the separation surface where the upper surface of the sheet bundle S is separated from the pickup roller 40. This is the position where the upper layer sheet having high adhesion between the sheets in the sheet bundle S is lowered so as to be positioned within the range of the first hot air outlet 155.

  The control unit 300 includes an information input / output unit 85, a warm air control unit 90, a lifting mechanism control unit 80, and a storage unit 84.

  The information input / output unit 85 includes a position detection signal from the position detection sensor 39, a rotation driving start signal for the pickup roller 40 from the paper feed motor M1, a first time-up signal from the first timer 86, and a second time from the second timer 87. An up signal, a cassette selection signal, a hot air request signal, and the like are input from the CPU 210 on the printer body 200 side.

  The warm air control unit 90 controls the driving of the lateral warm air mechanism 150 and the upper warm air mechanism 140 based on the cassette selection signal and the warm air request signal. That is, based on these input signals, the hot air control unit 90 sends control signals for driving the horizontal hot air mechanism 150 and the upper hot air mechanism 140 via the information input / output unit 85 to the drive motors ( (Not shown).

  The elevating mechanism control unit 80 includes a descending drive determining unit 82 and an ascending drive determining unit 83, and is based on the first time-up signal from the first timer 86 and the second time-up signal from the second timer 87. The lift drive 31 is controlled so that the lift plate 31 performs a separation operation that is displaced between the paper feed position and the separation position.

  Based on the first time-up signal from the first timer 86, the descent drive determination unit 82 outputs a control signal for descent driving the push-up member 32 to the stepping motor M2 via the information input / output unit 85. Similarly, the ascending drive determination unit 83 outputs a control signal for ascending driving of the push-up member 32 to the stepping motor M2 via the information input / output unit 85 based on the second time-up signal from the second timer 87. .

  The storage unit 84 stores, for example, a first type-up value of a plurality of first timers 86, a second time-up value of a second timer 87, according to a sheet feeding speed, a selected sheet size, material, mode, and the like. The number of driving steps of the stepping motor M2 that drives the push-up member 32 up and down, the operation program of each control unit, and the like are stored. In addition, the storage unit 84 is provided with a storage area for temporarily storing determination results and other information.

  The control unit 300 can be configured by, for example, a CPU, a memory (such as a ROM and a RAM), an input interface, and an output interface.

  Next, with reference to FIG. 13 and FIG. 14, the control process by the control unit 300 according to the present embodiment will be described.

  First, when a cassette selection signal and a hot air request signal are input from the CPU 210 on the printer main body 200 side via the information input / output unit 85 (S1), the hot air control unit 90 performs a horizontal operation based on these input signals. Drive signals for driving the first heater 152 and the first fan 151 of the warm air mechanism 150 are output to the drive motor (not shown) of the horizontal warm air mechanism 150 via the information input / output unit 85, respectively. Thereby, the blowing of warm air to the side surface parallel to the sheet feeding direction of the sheet bundle S is started (S2).

  Based on the cassette selection signal and the hot air request signal, the ascending drive determination unit 83 of the elevating mechanism control unit 80 outputs a control signal for ascending the push-up member 32 to the stepping motor M2 via the information input / output unit 85. . Thereby, the raising drive of the raising member 32 is started (S3). Next, based on the position detection signal from the position detection sensor 39 (FIG. 5, FIG. 17 to FIG. 19), the ascending drive determining unit 83 picks up the lift plate 31 and the upper surface of the sheet bundle S placed thereon. It is determined whether or not it has been lifted up to the paper feed position (FIG. 17) in contact with the roller 40 (S4). The stepping motor M2 continues to drive the push-up member 32 upward until the lift plate 31 is raised to the paper feed position. On the other hand, if it is determined that the lift plate 31 has been raised to the paper feed position based on the position detection signal (YES in S4), the ascending drive determination unit 83 stops the operation of the stepping motor M2, thereby pushing up the lifting member. The ascending drive 32 stops (S5).

  When the paper feed motor M1 that rotationally drives the pickup roller 40 is operated at this paper feed position, the first timer 86 starts simultaneously (S6). Next, the descending drive determination unit 82 determines whether or not a preset first predetermined time has elapsed based on the first time-up signal from the first timer 86 (S7). The first timer 86 keeps counting until the first predetermined time elapses, and the lift plate 31 is held at the paper feeding position. On the other hand, if it is determined that the first predetermined time has elapsed based on the first tie map signal (YES in S7), the lowering drive determination unit 82 outputs a control signal for driving the push-up member 32 downward to the stepping motor M2. Is output via the information input / output unit 85. As a result, the stepping motor M2 is operated, and the downward driving of the push-up member 32 is started (S8).

  Here, the number of drive steps of the stepping motor M2 required to drive the push-up member 32 downward and displace the lift plate 31 from the paper feed position to the separation position is calculated in advance, and the drive step number is stored in the storage unit. 84 is preferably stored. In addition, as the number of driving steps, a plurality of values corresponding to the type, size, printing speed, and the like of the selected sheet are stored in the storage unit 84, and the descending drive determination unit 82 responds to the selected condition. It can be configured to read from the storage unit 84 as appropriate.

  Next, the descent drive determination unit 82 determines whether or not the descent drive of the push-up member 32 has been completed (the descent drive of a preset number of steps has been completed) to the separation position of the lift plate 31 (FIG. 19). Judgment is made (S9). The stepping motor M2 continues to drive the push-up member 32 downward until the lift plate 31 is separated. On the other hand, when the descent driving of the preset number of steps is completed and the lift plate 31 is lowered to the separation position (YES in S9), the stepping motor M2 stops operating (descent driving stop) and the second timer 87 is simultaneously activated. Start (S10).

  Next, the ascending drive determination unit 83 determines whether or not a preset second predetermined time has elapsed based on the second time-up signal from the second timer 87 (S11). The second timer 87 keeps counting until the second predetermined time elapses, and the lift plate 31 is held at the separated position. On the other hand, when it is determined that the second predetermined time has elapsed based on the second time-up signal (YES in S11), the ascending drive determination unit 83 outputs a control signal for driving the pushing-up member 32 to the information input / output. It outputs to the stepping motor M2 via the part 85. As a result, the stepping motor M2 is activated, and the upward driving of the push-up member 32 is started. That is, the control sequence returns to S3 and the above steps are repeated.

  Here, the number of drive steps of the stepping motor M2 required to drive the push-up member 32 upward and displace the lift plate 31 from the separation position to the paper feed position is calculated in advance, and the drive step number is stored in the storage unit. 84 is preferably stored. In addition, as the number of driving steps, a plurality of values corresponding to the type, size, printing speed, and the like of the selected sheet are stored in the storage unit 84, and the ascending drive determination unit 83 is in accordance with the selected condition. It can be configured to read from the storage unit 84 as appropriate.

  In this embodiment, the timing at which the lift plate 31 is driven to rise from the separated position by the push-up member 32 is controlled by the timer value from the descent drive stop (descent drive completion). However, the present invention is not limited to this, and may be controlled by a timer value from the start of lowering drive, or controlled by a timer value from the start of paper feed (start of rotation of the paper feed motor M1 that drives the pickup roller 40). May be.

  According to the above-described configuration according to the present embodiment, as shown in FIGS. 17 to 19, the sheet feeding position where the upper surface of the sheet bundle S is once in contact with the pickup roller 40 by the elevating mechanism control unit 80 (FIG. 17). The lift plate 31 raised to the position shown in FIG. 18 is lowered to the state shown in FIG. 18 and further lowered to the separation position (FIG. 19) separated from the pickup roller 40, and then again raised to the paper feed position. As described above, the warm air is blown from the lateral warm air mechanism 150 to the side surface parallel to the sheet feeding direction of the sheet bundle S while performing the separating operation of displacing the lift plate 31 between the sheet feeding position and the separating position. Is controlling.

  That is, at the paper feed position, as shown in FIG. 17, since the upper surface of the sheet bundle S is pressed by the pickup roller 40, the gap between the sheets is small. For this reason, even if hot air is blown to the side surface parallel to the paper feeding direction of the sheet bundle S at the paper feeding position, it is difficult for hot air to enter the place away from the hot air outlet 155. Therefore, in the present embodiment, control is performed so that the above-described separation operation is performed during the period of the horizontal warm air blowing by the horizontal warm air mechanism 150. Since the gap between the sheets of the sheet bundle S can be widened by this separation operation, even hot air applied in a spot manner can be easily blown to a place away from the hot air outlet 155. As a result, it is possible to realize a lateral warm air mechanism that has higher sheet rolling efficiency than a large-sized lateral warm air assist as in the prior art, and thus the size of the entire sheet feeding device can be reduced.

  In particular, in the case of continuously feeding a plurality of sheet-like recording media, the sheet feeding effect by the hot air blowing with the separation operation according to the present embodiment is realized while maintaining a desired sheet feeding conveyance speed. Is required. For this reason, it is desirable to control the start timing of the descent drive of the elevating mechanism 30 so that the lift plate 31 descends at the earliest timing at which stable conveyance of the sheet can be ensured.

  If the lift plate 31 is lowered before the uppermost sheet P sent out from the pickup roller 40 is on the stable conveyance path, problems such as misalignment of the sheet P and paper jams occur. . On the other hand, if the timing of lowering the lift plate 31 is too late, the state where the upper surface of the sheet bundle S is pressed against the pickup roller 40 continues for a long time, so that a sufficient sheet blowing effect by hot air blowing with separation operation is obtained. I can't.

  That is, for example, assuming that the time until the leading edge of the sheet P sent to the pickup roller 40 passes through the pair of roller pairs 41 and 42 provided on the downstream side in the conveying direction is the first predetermined time, the pickup roller 40 When the conveyance of the sheet P fed to the end of the sheet is delayed, the sheet P is not held between any pair of rollers, and a stable sheet feeding state cannot be maintained.

  On the other hand, when the time during which the sheet P passes through the roller pairs 41 and 42 and is conveyed to the downstream conveying roller pair 37 (see FIG. 3) is a first predetermined time, the sheet P is separated from the pickup roller 40. Even so, the leading end of the sheet P is sandwiched between the pair of conveying rollers 37, and the trailing end is sandwiched between the pair of rolling rollers 41 and 42. In this state, it is possible to maintain a stable paper feeding state as compared with a state in which the sheet P is held only between the pair of roller rollers 41 and 42. Further, even when the conveyance of the sheet P sent to the pickup roller 40 is delayed, the sheet P is sandwiched at least between the pair of rolling rollers 41 and 42. For this reason, problems such as sheet misalignment are unlikely to occur.

  In this way, the first predetermined time set for the first timer 86 (the time for holding the lift plate 31 at the paper feeding position) reaches the conveying roller pair 37 after the pickup roller 40 starts sending the sheet P. If it is set to the time required until the time, the lowering of the lift plate 31 is started at the earliest timing at which stable conveyance of the sheet P can be ensured. For this reason, it is possible to more effectively spread the sheet bundle prior to sheet feeding by blowing warm air accompanied by the separation operation.

  In the present embodiment, the lower drive start timing for lowering the lift plate 31 from the paper feed position to the separation position and the upward drive start timing for raising the lift plate 31 from the separation position to the paper feed position are The first timer 86 and the second timer 87 are used for control. For this reason, the first time-up value of the first timer 86 and the second time-up value of the second timer 87 are appropriately changed according to the paper feed speed (image forming speed) of each paper feed unit 130, the material of the sheet, and the like. -It is possible to easily adjust to the optimal descent / rise start timing simply by adjusting.

  In the above-described control process, the case where only the horizontal warm air mechanism 150 is used as the sheet blowing mechanism using warm air has been described. However, when the upper warm air mechanism 140 is used in combination, the sheet feeding mechanism is more efficient prior to paper feeding. Sheets can be rolled.

Second Embodiment
A sheet feeding unit according to another embodiment of the present invention will be described below with reference to FIGS.

  FIG. 15 is a functional block diagram of a control unit that controls the warm air blowing operation with the separation operation according to the present embodiment. FIG. 16 is a flowchart showing a control process by the controller shown in FIG.

  For convenience of explanation, the same members as those shown in the drawings of the above embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  As shown in FIG. 3, the sheet feeding device 130 according to the present embodiment is provided with a conveyance switch 49 adjacent to the conveyance roller pair 37 on the downstream side in the sheet feeding direction of the conveyance roller pair 37.

  In the first embodiment described above, the timing at which the lift plate 31 is driven to move down and up by the push-up member 32 is controlled based on the first time-up signal from the first timer 86 and the second time-up signal from the second timer 87. It was. In the present embodiment, instead of these time-up signals, the lift plate 31 is separated from the paper feed position based on the first detection signal and the second detection signal of the transport switch (front end detection unit / rear end detection unit) 49. The second embodiment is different from the first embodiment in that the timing of the lowering / raising drive of the push-up member 32 that is displaced between the positions is controlled.

  Next, with reference to FIG.15 and FIG.16, the control process of the sheet rolling operation | movement by the warm air blowing accompanying the separation operation | movement which concerns on this embodiment is demonstrated.

  As shown in the functional block diagram of FIG. 15, the paper feeding unit 130 according to the present embodiment sprays hot air with a separating operation in which the lift plate 31 is displaced between the paper feeding position and the separating position by the push-up member 32. Is provided with a control unit 400 for controlling the sheet rolling operation. The control unit 400 includes an information input / output unit 285, a hot air control unit 290, an elevating mechanism control unit 280, and a storage unit 284.

  The information input / output unit 285 receives a position detection signal from the position detection sensor 39, a first detection signal and a second detection signal from the transport switch 49, a cassette selection signal and a hot air request signal from the CPU 210 on the printer body 200 side. Is done.

  The warm air control unit 90 controls the driving of the lateral warm air mechanism 150 and the upper warm air mechanism 140 based on the cassette selection signal and the warm air request signal. That is, based on these input signals, the hot air control unit 90 sends control signals for driving the horizontal hot air mechanism 150 and the upper hot air mechanism 140 via the information input / output unit 85 to the drive motors ( (Not shown).

  The elevating mechanism control unit 280 includes a descending drive determining unit 282 and an ascending drive determining unit 283, and controls the elevating drive of the elevating mechanism 30 based on the first detection signal and the second detection signal from the transport switch 49, The lift plate 31 is controlled so as to perform a separation operation in which the lift plate 31 is displaced between the paper feeding position and the separation position.

  The descending drive determination unit 282 outputs a control signal for driving the push-up member 32 downward to the stepping motor M2 via the information input / output unit 285 based on the first detection signal from the transport switch 49 as the leading end detection unit. . Similarly, the ascending drive determination unit 283 generates a stepping motor via the information input / output unit 285 via the information input / output unit 285 based on the second detection signal from the transport switch 49 serving as the rear end detection unit. Output to M2.

  The storage unit 284 stores, for example, the number of driving steps of the stepping motor M2 that drives the lift plate 32 up and down according to the size, material, mode, etc. of the selected sheet, the operation program of each control unit, and the like. The storage unit 284 is provided with a storage area for temporarily storing the determination result and other information.

  The hot air control unit 400 can be constituted by, for example, a CPU, a memory (such as a ROM and a RAM), an input interface, and an output interface.

  Next, with reference to FIG. 15 and FIG. 16, the control process by the control part 400 which concerns on this embodiment is demonstrated.

  First, when a cassette selection signal and a hot air request signal are input from the CPU 210 on the printer main body 200 side via the information input / output unit 285 (S101), the hot air control unit 290, based on these input signals, Drive signals for driving the first heater 152 and the first fan 151 of the warm air mechanism 150 are output to the drive motor (not shown) of the horizontal warm air mechanism 150 via the information input / output unit 285, respectively. Thereby, the hot air blowing to the side surface parallel to the sheet feeding direction of the sheet bundle S is started (S102).

  The ascending drive determination unit 283 of the elevating mechanism control unit 280 outputs a control signal for raising the push-up member 32 to the stepping motor M2 via the information input / output unit 285 based on the cassette selection signal and the hot air request signal. . Thereby, the raising drive of the pushing-up member 32 is started (S103). Next, based on the position detection signal from the position detection sensor 39 (FIGS. 5 and 17 to 19), the ascending drive determination unit 283 has the lift plate 31 and the upper surface of the sheet bundle S placed on the lift plate 31. It is determined whether or not it has been driven up to the paper feed position (FIGS. 3 and 17) that contacts the pickup roller 40 (S104). The stepping motor M2 continues to drive the push-up member 32 upward until the lift plate 31 is raised to the paper feed position. On the other hand, when it is determined that the lift plate 31 has been raised to the paper feed position based on the position detection signal (YES in S140), the ascending drive determination unit 283 stops the operation of the stepping motor M2, thereby pushing up the lifting member. The ascending drive 32 stops (S105).

  At this sheet feeding position, the sheet feeding motor M1 that rotationally drives the pickup roller 40 is operated to start feeding the sheet P (S106). Next, the descending drive determination unit 282 determines whether or not the leading end portion of the sheet P has reached the conveyance roller pair 37 based on the first detection signal from the conveyance switch 49 (S107). The lift plate 31 is held at the paper feed position until the descending drive determination unit 282 determines that the leading edge of the sheet P has reached the conveyance roller pair 37. On the other hand, when it is determined that the leading edge of the sheet P has reached the pair of conveying rollers 37 based on the first detection signal (YES in S107), the lowering drive determination unit 282 is a control signal for driving the push-up member 32 downward. Is output to the stepping motor M2 via the information input / output unit 285. As a result, the stepping motor M2 is operated, and the push-up member 32 is driven downward (S108).

  Here, the number of drive steps of the stepping motor M2 required to drive the push-up member 32 downward and displace the lift plate 31 from the paper feed position to the separation position is calculated in advance, and the drive step number is stored in the storage unit. It is desirable to store in 284. In addition, as the number of driving steps, a plurality of values corresponding to the selected sheet type, size, printing speed, and the like are stored in the storage unit 284, and the descending drive determination unit 282 is set according to the selected condition. It can be configured to read from the storage unit 284 as appropriate.

  Next, the descent drive determination unit 282 determines whether or not the descent drive of the push-up member 32 is completed (the descent drive of the preset number of steps is completed) to the separation position of the lift plate 31 (FIG. 19). Judgment is made (S109). The stepping motor M2 continues to drive the push-up member 32 downward until the lift plate 31 is separated. On the other hand, when the descent driving of the preset number of steps is completed and the lift plate 31 is lowered to the separation position (YES in S109), the stepping motor M2 stops operating, and the descent drive of the lift plate 31 by the push-up member 32 is performed. Stop (S110).

  Next, the ascending drive determination unit 283 determines whether or not the rear end portion of the sheet P has reached the conveyance roller pair 37 based on the second detection signal from the conveyance switch 49 as the rear end detection unit ( S111). The lift plate 31 is held at the separated position until the ascending drive determination unit 283 determines that the trailing edge of the sheet P has reached the conveyance roller pair 37. On the other hand, when it is determined that the trailing edge of the sheet P has reached the conveyance roller pair 37 based on the second detection signal (YES in S111), the ascending drive determination unit 283 performs control for driving the push-up member 32 to ascend. The signal is output to the stepping motor M2 via the information input / output unit 285. As a result, the stepping motor M2 is operated, and the upward driving of the push-up member 32 is started. That is, the control sequence returns to S103, and the above steps are repeated.

  Here, the number of drive steps of the stepping motor M2 required to drive the push-up member 32 upward and displace the lift plate 31 from the separation position to the paper feed position is calculated in advance, and the drive step number is stored in the storage unit. It is desirable to store in 284. In addition, as the number of driving steps, a plurality of values corresponding to the type, size, printing speed, and the like of the selected sheet are stored in the storage unit 284, and the ascending drive determination unit 283 responds to the selected condition. It can be configured to read from the storage unit 284 as appropriate.

  According to the above-described configuration according to the present embodiment, as shown in FIGS. 17 to 19, the sheet feeding position where the upper surface of the sheet bundle S is once in contact with the pickup roller 40 by the elevating mechanism control unit 280 (FIG. 17). The lift plate 32 raised to the position shown in FIG. 18 is lowered to a state shown in FIG. 18 and further lowered to a separation position (FIG. 19) separated from the pickup roller 40, and then is raised again to the paper feed position. As described above, the warm air is blown from the lateral warm air mechanism 150 to the side surface parallel to the sheet feeding direction of the sheet bundle S while performing the separating operation of displacing the lift plate 31 between the sheet feeding position and the separating position. Is controlling.

  That is, at the paper feed position, as shown in FIG. 17, since the upper surface of the sheet bundle S is pressed by the pickup roller 40, the gap between the sheets is small. For this reason, even if hot air is blown to the side surface parallel to the paper feeding direction of the sheet bundle S at the paper feeding position, it is difficult for hot air to enter the place away from the hot air outlet 155. Therefore, in the present embodiment, control is performed so that the above-described separation operation is performed during the period of the horizontal warm air blowing by the horizontal warm air mechanism 150. Since the gap between the sheets of the sheet bundle S can be widened by this separation operation, even hot air applied in a spot manner can be easily blown to a place away from the hot air outlet 155. As a result, it is possible to realize a lateral warm air mechanism that has higher sheet rolling efficiency than a large-sized lateral warm air assist as in the prior art, and thus the size of the entire sheet feeding device can be reduced.

  As in the first embodiment, the control process when only the horizontal warm air mechanism 150 is used as the sheet blowing mechanism using warm air has been described. Sheets can be spread more efficiently.

  In each of the embodiments, when the same type of sheet P is stored in a plurality of paper supply units 130, the paper supply position and the separated position are defined as a plurality of paper supply units that store the same type of sheet P. It is desirable to control so that it is shifted between 130 and fed alternately.

  According to the above configuration, it is possible to realize a sheet winding mechanism using hot air with high sheet winding efficiency without reducing the number of printed sheets per unit time, and particularly when coated paper is used. Benefits can be especially enjoyed.

  The sheet feeding device of the present invention can be applied to all image forming apparatuses such as a printer, a copier, a facsimile, or a complex machine having these functions combined, and is particularly suitable for a small-sized image forming apparatus. It can be used suitably.

    DESCRIPTION OF SYMBOLS 1 ... Printer (image forming apparatus), 30 ... Elevating mechanism, 31 ... Lift plate (sheet stacking plate), 32 ... Push-up member (elevating mechanism), 33 ... Rear end cursor, 34a, 34b ... Width Alignment cursor pair, 35... Sheet storage section, 36... Drive shaft (elevating mechanism), 37... Transport roller pair, 38... Support section, 39. Paper feed roller, 42... Rolling roller, 49... Transport switch (front end detection unit / rear end detection unit), 56... Top plate, 80 ... Elevating mechanism control unit, 82. ... ascending drive determination unit, 84 ... storage unit, 85 ... information input / output unit, 86 ... first timer, 87 ... second timer, 90 ... warm air control unit, 100 ... sheet supply unit, 130 ... Paper feed unit (paper feeder), 130A ... Paper feed cassette, 130B... Paper feed unit main body, 133... Paper feed conveyance path, 140... Upper hot air mechanism (second hot air mechanism), 141. 2 heaters (heating unit), 143 ... upper hot air chamber (air blowing unit), 144 ... second suction port (air blowing unit), 145 ... second hot air outlet (air blowing unit), 150 ... side hot air Mechanism (first hot air mechanism), 151... First fan, 152... First heater (heating unit), 153 .. side warm air chamber (air blowing unit), 154. 155... First warm air outlet (blower), 200... Printer body, 280... Lifting mechanism controller, 282. Descending drive determining section, 283. 285 ... Information input / output unit, 290 ... Hot air control unit, 300 ... Control unit, 400 ... Control unit, P ... Over DOO, S ...... sheet bundle, M1 ...... feed motor, M2 ...... stepping motor (lift mechanism)

Claims (5)

A sheet feeding device capable of continuously feeding a sheet-like recording medium to a predetermined conveyance path,
An apparatus body forming at least a part of the transport path;
A sheet cassette that includes a sheet storage unit that stores a sheet bundle made of a plurality of sheet-like recording media, and that can be pulled out from the apparatus main body;
A sheet placing plate on which an upstream end in a sheet feeding direction is rotatably supported in the sheet storage unit and stacks the sheet bundle;
A pickup roller that contacts the upper surface of the sheet bundle and feeds the uppermost sheet-like recording medium of the sheet bundle;
A retracted position in which the sheet placing plate is lowered to the bottom, a sheet feeding position in which the sheet placing plate is lifted from the retracted position, and an upper surface of the sheet bundle is in contact with a pickup roller, the retracted position, and the An elevating mechanism that is positioned between a sheet feeding position and displaces the sheet placing plate between a separation position where the upper surface of the sheet bundle is separated from the pickup roller;
Opposite to the sheet bundle so as to include a top surface of the sheet bundle contacting the pickup roller at the paper feeding position and a part of the sheet bundle at the separation position in a vertical sectional view along the paper feeding direction. A first hot air mechanism that blows hot air on a side surface parallel to the sheet feeding direction of the sheet bundle stored in the sheet storage unit,
Control means for controlling the lifting drive of the lifting mechanism,
The control unit is configured to place the sheet placed at the paper feeding position during a hot air blowing operation by the first hot air mechanism including a period during which a plurality of sheet-like recording media are continuously fed by the pickup roller. After the plate is lowered to the separation position, the raising / lowering drive of the raising / lowering mechanism is controlled so as to rise again to the paper feeding position ,
The paper feeding device, wherein the first hot air mechanism is provided in the device main body . The first warm air mechanism is
A suction port that is disposed opposite to the sheet feeding cassette on the upstream side of the pickup roller in the sheet feeding direction, and sucks air;
An air path for guiding the air taken in from the suction port in the paper feeding direction;
A heater disposed in the air path and heating the air;
The air heated by the heater is directed toward a side surface parallel to the sheet feeding direction of the sheet bundle stored in the sheet storage unit and upstream in the sheet feeding direction with respect to the width direction of the sheet bundle. An outlet that blows off at an angle,
The sheet feeding device according to claim 1 , further comprising: A pair of conveying rollers provided on the downstream side of the pickup roller in the sheet feeding direction and sandwiching and conveying the sheet-like recording medium fed by the pickup roller;
A leading edge detection unit that detects a state in which a leading edge in a sheet feeding direction of the sheet-like recording medium sent out by the pickup roller passes between the pair of conveying rollers;
The control means controls the elevating mechanism so that the sheet placing plate starts to descend from the sheet feeding position to the separated position when the leading edge detection unit detects the state. The sheet feeding device according to claim 1 or 2 . A pair of conveying rollers provided on the downstream side of the pickup roller in the sheet feeding direction and sandwiching and conveying the sheet-like recording medium fed by the pickup roller;
A rear end detector that detects a state in which a rear end in the sheet feeding direction of the sheet-like recording medium sent out by the pickup roller passes between the pair of transport rollers, and
The control means controls the elevating mechanism so that the sheet placing plate starts to rise from the separated position to the sheet feeding position when the rear end detection unit detects the state. The sheet feeding device according to claim 1 or 2 . A paper feeding device according to any one of claims 1 to 4 ,
An image forming apparatus comprising: an image forming unit configured to form an image on a sheet-like recording medium fed from the paper feeding device.

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