JP2010037035A - Sheet feeding device and image forming device with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize a sheet feeding device with a sheet separating mechanism by a warm air assist installable even in a small space. <P>SOLUTION: When a prescribed sheet feeding unit 130 is selected for forming an image, and it is determined that a lift plate 31 is raised to a sheet feeding position, a control section 300 executes control for continuously driving a DC motor M2 driving a drive shaft 36 of a push-up member 32 until a lowering drive time T1 corresponding to the detected remaining amount of sheets P elapses based on the amount of sheet bundles S placed on the lift plate 31 detected with a sheet residual amount detecting part 211. <P>COPYRIGHT: (C)2010,JPO&INPIT

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 adhere to 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 a first aspect of the present invention is a sheet feeding device capable of continuously feeding sheet-like recording media to a predetermined conveyance path, and stores a sheet bundle composed of a plurality of sheet-like recording media. An upstream end in the sheet feeding direction is rotatably supported in the sheet storage unit, and abuts against the upper surface of the sheet bundle. A pickup roller that feeds out the uppermost sheet-like recording medium, and one end that is pivotally supported by a pivot shaft, and the other end abuts against the bottom surface of the sheet placing plate and pushes up the sheet placing plate A sheet feeding position where the upper surface of the sheet bundle comes into contact with the pickup roller and the upper surface of the sheet bundle is at a certain distance from the pickup roller by rotating the push-up member about the rotation axis. An elevating mechanism for displacing the sheet placing plate between the separated positions, and a first hot air mechanism for blowing warm air on a side surface parallel to the sheet feeding direction of the sheet bundle stored in the sheet storage unit; A sheet remaining amount detecting means for detecting the amount of the sheet-like recording medium stacked on the sheet placing plate, and a control unit for controlling the raising / lowering drive of the raising / lowering mechanism, wherein the control unit comprises the first During the hot air blowing operation by the hot air mechanism, the raising / lowering drive of the elevating mechanism is controlled so that the sheet placing plate is displaced between the sheet feeding position and the separation position, and the sheet remaining amount detecting means The elevating mechanism is controlled so as to change the rotation amount of the rotating shaft in the separating operation according to the detected amount of the sheet-like recording medium.

  According to the above configuration, the one end is rotatably supported by the rotation shaft, and the other end includes the push-up member that abuts the bottom surface of the sheet placement plate and pushes up the sheet placement plate. By driving the moving shaft and rotating the push-up member, 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 by a certain distance are provided. And an elevating mechanism for displacing the sheet placing plate between the first and second hot air mechanisms for blowing hot air onto a side surface parallel to the sheet feeding direction of the sheet bundle stored in the sheet storage unit.

  In a small sheet feeding device using the above-described cantilever lifting mechanism (a mechanism for moving up and down a sheet placing plate whose upstream end in the sheet feeding direction is rotatably supported), a large warm air mechanism It is difficult to install a hot air sowing mechanism. Therefore, there is a need for a hot air mechanism that has high sheet-rolling efficiency and can efficiently roll a sheet bundle 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 controller that controls the raising / lowering drive of the elevator mechanism, and the controller controls the 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 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 to the sheet feeding position. As it is, the paper is 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, according to the present invention, 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 (lateral warm air mechanism) is performed. In addition, the elevating drive of the elevating mechanism is controlled.

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

  Since the gap between the sheets of the sheet bundle can be widened by the above-described separation operation, even hot air applied in a spot manner can be easily blown to a place away from the hot air outlet of the first hot air mechanism. . 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. .

  Further, according to the above configuration of the present invention, the control unit that controls the raising / lowering drive of the raising / lowering mechanism may perform the separation operation in accordance with the amount of the sheet-like recording medium detected by the remaining sheet amount detecting unit. The elevating mechanism is controlled so as to change the rotation amount of the rotation shaft. This employs a configuration in which the other end of the push-up member whose one end is rotatably supported by a rotation shaft is brought into contact with the bottom surface of the sheet placement plate and the sheet placement plate is pushed up. by.

  That is, in the above configuration, if the rotating shaft is rotated in the direction in which the sheet bundle descends at the same rotational speed for the same time or the same rotational angle, the descending amount of the sheet placing plate in the separating operation is This differs depending on the amount of the sheet-like recording medium placed on the sheet placing plate. Specifically, as the amount of the sheet-like recording medium decreases, the descending amount of the elevating mechanism also decreases (see h1, h2, and h3 in FIG. 14). Further, as the amount of the sheet-like recording medium decreases, the lowering amount of the elevating mechanism also decreases as the load decreases. In this case, when the amount of the sheet-like recording medium is small, there may be a case where the lowering amount of the lifting mechanism necessary for efficiently blowing the warm air from the first warm air mechanism between the sheets cannot be secured.

  Therefore, the present invention is configured to control the elevating mechanism so as to change the rotation amount of the rotating shaft in the separation operation according to the amount of the sheet-like recording medium detected by the sheet remaining amount detecting means. did. As a result, it is possible to ensure the amount of lowering of the sheet-like recording medium necessary for stably blowing efficiently between the sheets, regardless of the amount of the sheet-like recording medium placed on the sheet placing plate.

  In the above configuration, the rotation shaft is a drive shaft, and the elevating mechanism rotates the push-up member by driving the drive shaft, so that the lift mechanism moves between the paper feeding position and the separation position. The control unit is configured to displace a sheet placement plate, and the control unit determines a rotation amount of the drive shaft in the separation operation according to an amount of the sheet-like recording medium detected by the sheet remaining amount detection unit. It is good also as a structure which controls the said raising / lowering mechanism so that it may change (Claim 2).

  In the above configuration, the storage unit that stores the descent drive time of the elevating mechanism according to the amount of the sheet-like recording medium, and the descent drive time read from the storage unit from the start of the descent drive of the elevating mechanism is counted. And a timer for reading out the descent drive time corresponding to the amount of the sheet-like recording medium from the storage unit based on a detection result of the remaining sheet amount detecting means. However, it is good also as a structure which controls the descent drive of the said raising / lowering mechanism so that the said drive shaft may be rotated until the said descent drive time is timed (Claim 3).

  Further, the elevating mechanism includes a stepping motor that rotates the drive shaft forward and backward, and the number of lowering drive steps of the stepping motor according to the amount of the sheet-like recording medium is stored in the storage unit, and the control unit Reads out the number of lowering drive steps of the stepping motor corresponding to the amount of the sheet-like recording medium from the storage unit based on the detection result of the remaining sheet amount detecting means, and the stepping motor corresponding to the number of lowering driving steps. It is good also as a structure which controls the descent drive of the said raising / lowering mechanism so that it may rotate.

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

  According to the above configuration, a lateral warm air mechanism (first warm air mechanism) having higher sheet rolling efficiency than a conventional large-sized lateral warm air assist can be realized as a sheet blowing mechanism using warm air. Therefore, the paper feeding device can be downsized. 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.

  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 the present embodiment. 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 feeding units 130 includes a transport mechanism that can be stacked and installed in the lower part of the printer main body 200, and a desired number of paper feeding units 130 can be attached to the printer main body 200 at any time. 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, the configuration of each paper feed unit (paper feed device) 130 mounted on the sheet supply unit 100 of the color printer 1 according to this embodiment will be described in detail with reference to FIGS. 1, 3, and 4. .

  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.

  As shown in FIG. 1, the paper feed unit 130 includes a paper feed cassette 130A and a paper feed unit main body 130B. The paper feed cassette 130A slides forward and backward with respect to the paper feed unit main body 130B. A general slide mechanism (drawer mechanism) can be adopted for the paper feed cassette 130A and the paper feed unit main body 130B.

  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).

  As shown in FIG. 4, the sheet feeding cassette 130 </ b> A of the sheet feeding unit 130 includes a width alignment cursor pair 34 a and 34 b for positioning the sheet P stored in the sheet storage unit 35 in the width direction, and a trailing end of the sheet P. And a rear end cursor 33 to be aligned. 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 (drive shaft) 36, a push-up member 32, and a drive connecting member (not shown) are provided as a lifting mechanism 30 (FIG. 15) that lifts and lowers the lift plate 31 in the lower part of the lift plate 31 in the sheet feeding direction. ing. Further, a receiving member (not shown) corresponding to the drive connecting member and a DC motor M2 (FIG. 15) 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. As a result, the power of the DC motor M <b> 2 can be transmitted to the drive shaft 36.

  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. As shown in FIG. 3, when 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).

  Next, the configuration of the remaining sheet amount detection unit 211 mounted on the sheet feeding unit 130 according to the present embodiment will be described with reference to FIGS. 3, 5, and 6.

  FIG. 5 is an explanatory diagram of an actuator constituting the remaining sheet amount detection unit according to the present embodiment. FIG. 6 is a perspective view illustrating a configuration of a remaining sheet amount detecting unit mounted on the sheet feeding device according to the present embodiment.

  As shown in FIG. 3, the sheet feeding unit 130 according to the present embodiment includes a sheet remaining amount detection unit (sheet remaining amount detection unit) 211 that detects the amount of sheets stacked on the lift plate 31.

  As shown in FIG. 3, the sheet remaining amount detection unit 211 detects the behavior of the actuator 221 attached to the tip of the support body 202 that fixes the pickup roller 40 via the elastic member 229, and the electrical signal. And a detector 220 that outputs as follows.

  As shown in FIGS. 5 and 6, the actuator 221 includes a main body 225, a contact portion 222 that is formed on one end side of the main body portion 225 and contacts the upper surface of the sheet bundle S, and on the other end side of the main body portion 225. A rotation shaft 223 that is provided and pivotally supports the main body 225 and a light shielding portion 224 formed at the end of the main body 225 on the rotation shaft 223 side are provided. On the other hand, the detector 220 includes a pair of photo interrupters 220a and 220b of the same type.

  FIG. 5A shows a side view of the actuator 221, and FIG. 5B shows a perspective view of the actuator 221. As shown in FIG. 5B, the light shielding portion 224 of the actuator 221 includes a portion 224a that crosses the optical axis α of the photo interrupter 220a and a portion that crosses the optical axis β of the photo interrupter 220b, A portion 224b formed in a different shape is formed by a single plate-like member.

Here, as shown in FIG. 5A, the distance r ₂ between the rotation center O of the rotation shaft 223 of the actuator 221 and the optical axis α of the photointerrupter 220a, the rotation center O and the optical axis β of the photointerrupter 220b, and Distance r ₁ and r ₂ > r ₁ are satisfied.

  In the sheet remaining amount detection unit 211, the light shielding unit 224 crosses the optical axis α of the photo interrupter 220a or the optical axis β of the photo interrupter 220b according to a change in the contact angle between the upper surface of the sheet bundle S and the contact unit 222. Thus, an ON / OFF signal is generated. As a result, the remaining sheet amount detection unit 211 can detect the remaining sheet amount in four stages by the combination of the ON / OFF signals of the two photo interrupters 220a and 220b.

  That is, when the combination of the ON / OFF signals is expressed as (ON / OFF of the photo interrupter 220a, ON / OFF of the photo interrupter 220b), the sheet from the stage where the remaining amount of sheets shown in FIG. (ON, OFF (state shown in FIG. 5A)), (OFF, OFF), (OFF, ON (state shown in FIG. 6)), (ON, ON) in the order of the remaining amount. .

  In the above configuration, the distance between the optical axis of each of the plurality of detection units (photointerrupters) and the rotation center of the actuator may be different from each other. The actuator and the detection unit have the shape of the light shielding unit and the position of the rotation axis. It is not limited by the specific shape of the tip portion or the layout of each portion. In the above configuration, the remaining sheet amount detection unit 211 is configured by two photo interrupters, but may be three or more.

  As shown in FIGS. 2, 3, and 7 to 10, 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. 7 is an explanatory diagram illustrating the configuration of the sheet feeding device according to the present embodiment. FIG. 8 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. 9 is an explanatory diagram showing the hot air blowing direction of the horizontal hot air mechanism according to the present embodiment. FIG. 10 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. 7, a top plate 56 is formed in a portion where the side warm air mechanism 150 and the later-described upper warm air mechanism 140 are not formed on the upper surface of the sheet feeding unit main body 130B. The top plate 56 is closed.

  As shown in FIG. 7, the horizontal warm air mechanism 150 is provided along one side surface of the paper feed cassette 130 </ b> A in the paper feed direction. Further, as shown in FIG. 8, 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.

  As shown in FIG. 8, 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 (air blowing unit) 153 moves toward the first heater 152 due to the rotation of the first fan (air blowing unit) 151, the paper feed unit enters the lateral warm air chamber 153 from the first suction port 154. The air in 130 is taken in. The air that has moved to the first heater 152 side is heated by the first heater 152, and is blown out from the first hot air outlet (air blowing unit) 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. 9, the first hot air outlet 155 directs the warm air straight (in parallel) in the width direction of the sheet bundle S (the direction of arrow C in FIG. 9, which is a direction orthogonal to the sheet feeding direction). Instead of blowing out, as shown by an arrow B in FIG. 9, 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. 9, the hot air escapes from the side surface of the sheet bundle S to the downstream side in the sheet feeding direction as shown in FIG. 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 hot air toward the center of the sheet bundle S to be fed, as indicated by an arrow B in FIG. ing. Thereby, the hot air blown out 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, 7, and 11, the sheet feeding unit 130 according to the present embodiment is an upper warm air mechanism (first-order) in addition to the lateral warm air mechanism 150 as a sheet blowing mechanism by warm air blowing. 2 warm air mechanism) 140.

  FIG. 11 is a vertical cross-sectional view illustrating a configuration of a main part of the upper warm air mechanism mounted on the sheet 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. 11, 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 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 is likely 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. 12 and FIG. 13, a description will be given of the 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 sheet-rolling mechanism by hot air assist.

  FIG. 12 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. 13 is an explanatory diagram illustrating the direction in which the lateral warm air and the upper warm air are blown in the sheet feeding device 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.

  FIG. 13A to FIG. 13C 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.

  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. 13B is obtained. Further, the state immediately shifts to the state shown in FIG. 13C (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.

  Here, with reference to FIG. 14, the relationship between the remaining amount of the sheet bundle S placed on the lift plate 31 and the lowering amount when the lift plate 31 is driven downward by the lifting mechanism 30 will be described in detail below. explain. FIG. 14 is an explanatory diagram for explaining control of the lifting mechanism in the sheet feeding device according to the present embodiment.

  In order for the push-up member 32 to push up the lift plate 31 to the paper feeding position, it is necessary to push the lift plate 31 higher as the remaining amount of the sheet bundle S placed on the lift plate 31 is smaller. For example, it is assumed that the position of the push-up member 32 when the lift plate 31 is lifted to the sheet feeding position is X1, Y1, and Z1 (X1, Y1, and Z1 in ascending order of the remaining amount of the sheet bundle S). Then, the drive shaft 36 of the lifting mechanism is rotated in the downward direction by the same rotation angle θ from the positions X1, Y1, and Z1, and the positions where the push-up member 32 is lowered are respectively X2, Y2, and Z2.

  In the above case, the amount by which the lift plate 31 (and the sheet bundle S placed on the lift plate 31) descends due to the displacement of the push-up member 32 from X1 to X2 is represented by h1 in FIG. . When the length (that is, the rotation radius) of the push-up member 32 is r and the angles at the positions of X1 and X2 are θ1 and θ2 with reference to the case where the push-up member 32 is in the horizontal position, h1 is expressed by the following equation.

h1 = r (sin θ1-sin θ2)
Similarly, the amount by which the lift plate 31 is lowered due to the displacement of the push-up member 32 from Y1 to Y2 is represented by h2. If the angles at the positions of Y1 and Y2 are θ3 and θ4 with reference to the case where the push-up member 32 is in the horizontal position, h2 is expressed by the following equation.

h2 = r (sin θ3-sin θ4)
Similarly, the amount by which the lift plate 31 is lowered due to the displacement of the push-up member 32 from Z1 to Z2 is represented by h3. If the angles at the positions of Z1 and Z2 are θ5 and θ6 with reference to the case where the push-up member 32 is in the horizontal position, h3 is expressed by the following equation.

h3 = r (sin θ5-sin θ6)
In the above, the amount by which the lift plate 31 is lowered is h1 <h2 <h3. That is, when the drive shaft 36 of the elevating mechanism 30 is rotated in the descending direction from the sheet feeding position state by the same rotation angle θ, the amount by which the lift plate 31 descends decreases as the remaining amount of the sheet bundle S decreases.

  Therefore, in the present embodiment, when the lift plate 31 is driven downward from the paper feeding position to the separation position, the upper surface of the sheet bundle S and the pickup roller at the separation position are determined by the remaining amount of the sheet bundle S placed on the lift plate 31. The configuration is such that the distance from 40 does not vary greatly. That is, the lifting mechanism 30 is controlled so as to change the rotation amount of the drive shaft 36 in the separating operation according to the remaining amount of the sheet bundle S detected by the remaining sheet detection unit 211 (FIGS. 5 and 6). It is said. Specifically, the lifting mechanism 30 is controlled so that the amount of rotation of the drive shaft 36 increases as the remaining amount of the sheet bundle S decreases.

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

  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 operation by the control unit shown in FIG.

  As shown in the functional block diagram of FIG. 15, in the paper feeding unit 130 according to the present embodiment, the lift plate 31 is displaced between the paper feeding position and the separation position during the hot air blowing operation by the lateral hot air mechanism 150. As described above, the raising / lowering drive of the raising / lowering mechanism 30 is controlled, and the raising / lowering is performed so as to change the rotation amount of the drive shaft 36 in the separation operation according to the amount of the sheet bundle S detected by the remaining sheet amount detection unit 211. A control unit 300 that controls the mechanism 30 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 is in contact with the pickup roller 40, and the separation position is a position where the upper surface of the sheet bundle S is constant with the pickup roller 40. This is a position separated by a distance and is a position where the upper layer sheet P 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.

  At the paper feeding position, the upper surface of the sheet bundle S is pressed by the pickup roller 40, so the gap between the sheets is small. For this reason, even if warm air is blown to the side surface parallel to the sheet feeding direction of the sheet bundle S at the sheet feeding position, it is difficult for hot air to enter the place away from the first warm air outlet 155. Therefore, in the present embodiment, the lift plate 31 in which the upper surface of the sheet bundle S is raised to the sheet feeding position where the upper surface of the sheet bundle S abuts the pickup roller 40 during the period of the horizontal hot air blowing by the horizontal hot air mechanism 150 is used. Are lowered to the separated position, and then raised again to the sheet feeding position. 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 first 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.

  The control unit 300 according to the present embodiment includes an information input / output unit 85, a warm air control unit 90, an elevating mechanism control unit 80, and a storage unit 84.

  The information input / output unit 85 includes a position detection signal, a remaining amount detection signal from the sheet remaining amount detection unit 211, a first time-up signal from the first timer (timer) 86, a second time-up signal from the second timer 87, and a printer. A cassette selection signal, a hot air request signal, and the like are input from the CPU 210 on the main 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 and the warm air request signal. That is, based on these input signals, the warm air control unit 90 sends control signals for driving the horizontal warm air mechanism 150 and the upper warm air mechanism 140 via the information input / output unit 85 to drive motors ( (Not shown) etc.

  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.

  The descending drive determining unit 82 generates a control signal for driving the push-up member 32 to descend based on the position detection signal and the remaining amount detection signal from the sheet remaining amount detecting unit 211 and the first time-up signal from the first timer 86. And output to the DC motor M2 via the information input / output unit 85. Based on the second time-up signal from the second timer 87, the ascending drive determination unit 83 outputs a control signal for ascending driving of the push-up member 32 to the DC motor M2 via the information input / output unit 85.

  In the storage unit 84, a plurality of first type-up values (push-up members) of the first timer 86 corresponding to each descent driving time corresponding to the amount (remaining amount) of the sheet bundle S detected by the remaining sheet amount detecting unit 211. The driving time of the DC motor M <b> 2 that drives 32 to descend is stored.

  As described above, the remaining sheet amount detection unit 211 according to the present embodiment is configured to detect the remaining amount of the sheet bundle S in four stages. Therefore, the storage unit 84 stores four first type-up values corresponding to the amount of the four-stage sheet bundle S.

  Further, the storage unit 84 stores a plurality of second time-up values of the second timer 87 corresponding to the sheet feeding speed, the selected sheet size, material, mode, and the like, operation programs of the respective control units, and the like. Yes. 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.

  In the present embodiment, the DC motor M2 is employed as the drive motor for the push-up member 32. However, instead of this, for example, a stepping motor (not shown) that rotates the drive shaft 36 forward and backward may be employed.

  In addition, instead of the DC motor M2 or the stepping motor, the lift member 31 is moved between the paper feeding position and the separation position by rotating the push-up member 32 around the rotation shaft by using an urging means such as a spring. It is good also as a structure displaced between.

  In this case, a plurality (four in the configuration of the present embodiment) of the stepping motors corresponding to the amount of the sheet bundle S is stored in the storage unit 84, and the control unit 300 detects the remaining sheet amount. Based on the detection result of the unit 211, the stepping motor descending drive step number corresponding to the amount of the sheet-like recording medium is read from the storage unit 84, and the stepping motor is rotated by the descending driving step number. What is necessary is just to set it as the structure which controls the downward drive of the raising / lowering mechanism 30. FIG.

  Next, a control operation by the control unit 300 according to the present embodiment will be described with reference to FIGS. 15 and 16.

  When a cassette selection signal is input from the CPU 210 on the printer main body 200 side via the information input / output unit 85, the ascending drive determination unit 83 of the elevating mechanism control unit 80 drives the push-up member 32 up based on the cassette selection signal. The control signal to be output is output to the DC motor M2 via the information input / output unit 85. Thereby, the raising drive of the pushing-up member 32 is started. Next, when it is determined that the lift plate 31 has been raised to the sheet feeding position based on the position detection signal from the sheet remaining amount detection unit 211 (FIGS. 5 and 6), the lift drive determination unit 83 lifts the push-up member 32. Stop driving.

  In this state, the remaining amount detection unit 211 detects the amount (remaining amount) of the sheet bundle S placed on the lift plate 31 (S10).

  Based on the remaining amount detection signal of the sheet P detected by the remaining sheet amount detecting unit 211, the control unit 300 determines whether the amount (remaining amount) of the sheet P placed on the lift plate 31 is any of the above four steps. Is recognized (S20).

  The descending drive determination unit 82 reads the descending drive time T1 corresponding to the remaining amount of the sheet P recognized in S20 from the storage unit 84, and starts the first timer 86 that measures the descending drive time T1. As a result, the push-up member 32 starts to move away and descend. At the same time, the warm air control unit 90 outputs a control signal for driving the horizontal warm air mechanism 150 and the upper warm air mechanism 140 to a drive motor (not shown) of each unit via the information input / output unit 85 (S30). ).

  The descending drive determination unit 82 determines whether or not the descending drive time T1 has elapsed based on the first time-up signal from the first timer 86 (S40). That is, the DC motor M2 is continuously driven until the descent drive time T1 elapses in S40, and thereby, the separation member descent drive of the push-up member 32 is continued (S40). When it is determined that the descent drive time T1 has elapsed based on the first time-up signal from the first timer 86 (YES in S40), the descent drive determination unit 82 controls to stop the descent drive of the push-up member 32. The signal is output to the DC motor M2 via the information input / output unit 85. Thereby, the separation and descent driving is completed (S50).

  In this embodiment, when the separation and descent drive is completed in S50, the ascending drive determination unit 83 starts the second timer 87 that measures a predetermined descent holding time T2 (S60). Next, the ascending drive determination unit 83 determines whether or not a preset descent holding time T2 has elapsed based on the second time-up signal from the second timer 87 (S70). The second timer 87 keeps counting until the descent holding time T2 elapses, and the lift plate 31 is held at the separated position. On the other hand, if it is determined that the descent holding time T2 has elapsed based on the second time-up signal (YES in S70), the ascending drive determination unit 83 sends a control signal for driving the pushing-up member 32 to the information input / output. It outputs to the DC motor M2 via the unit 85. As a result, the DC motor M2 is operated, and the upward driving of the push-up member 32 is started (S80).

  After that, when the remaining sheet amount detecting unit 211 detects that the upper surface of the sheet bundle S placed on the lift plate 31 has reached the sheet feeding position, the ascending drive determining unit 83 A control signal for stopping the ascending drive is output to the DC motor M2 via the information input / output unit 85, and the ascending drive of the push-up member 32 is stopped (S90). Then, the feeding of the sheet P positioned at the uppermost layer of the sheet bundle S is started (S100). When the feeding of the sheet P is started, it is determined whether or not another sheet P should be fed (S110). Further, when there is a sheet P to be fed (YES in S110), the processing from S10 is repeated. On the other hand, if no further paper feeding is necessary (NO in S110), the process is terminated.

  In the above-described control operation, the case where the horizontal warm air mechanism 150 and the upper warm air mechanism 140 are used in combination as the sheet blowing mechanism by the warm air has been described. However, only the lateral warm air mechanism 150 is used. Also, the benefits of the present invention can be enjoyed.

  According to the above configuration, the elevating mechanism 30 is controlled so as to change the rotation amount of the drive shaft 36 in the separation operation in accordance with the amount of the sheet P detected by the remaining sheet amount detection unit 211. As a result, the amount of lowering of the sheet bundle S necessary for stably and efficiently blowing between sheets can be ensured regardless of the amount of sheets P (sheet bundle S) placed on the lift plate 31.

  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.

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 of the actuator which comprises the sheet | seat residual amount detection part which concerns on one Embodiment of this invention. FIG. 4 is a perspective view illustrating a configuration of a sheet remaining amount detection unit mounted on a sheet feeding device according to an embodiment of the present invention. It is explanatory drawing explaining the structure of the paper feeder which concerns on one Embodiment of this invention. FIG. 3 is a horizontal cross-sectional view illustrating a main part of a horizontal warm air mechanism mounted on a paper feeding device according to an embodiment of the present invention. It is explanatory drawing which shows the warm air blowing direction of the horizontal warm air mechanism which concerns on one Embodiment of this invention. It is explanatory drawing for demonstrating the warm air blowing state of the side warm air mechanism which concerns on one Embodiment of this invention. It is sectional drawing of the perpendicular direction which shows the principal part structure of the upper warm air mechanism mounted in the paper feeder which concerns on one Embodiment of this invention. It is a perspective view of the paper feed cassette for demonstrating the blowing direction of side warm air and top warm air concerning one embodiment of the present invention. It is explanatory drawing which shows the blowing direction of the side warm air and upper warm air which concern on one Embodiment of this invention. It is explanatory drawing for demonstrating control of the raising / lowering mechanism in the paper feeder which concerns on one Embodiment of this invention. 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 of the sheet rolling operation | movement by warm air blowing which concerns on this embodiment.

Explanation of symbols

    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 ... Alignment cursor pair 35... Sheet storage unit 36... Drive shaft (drive shaft, lifting mechanism) 37 37 Conveyance roller 38. Support unit 40. Pickup roller 41. ...... Powder roller 56 ... Top plate 80 ... Elevating mechanism control unit 82 ... Descent drive determination unit 83 ... Upward drive determination unit 8484 Storage unit 85 ... Information input / output unit 86 ... First timer (timer) 87... Second timer 90... Warm air control unit 100... Sheet supply unit 130 .. sheet feeding unit (sheet feeding device) 130 A. 130B …… Paper feed unit body, 133 …… Paper transport path, 140... Upper warm air mechanism (second warm air mechanism), 141... Second fan (blower), 142... Second heater (heater), 143. Part), 144... Second suction port (air blowing part), 145... Second hot air outlet (air blowing part), 150 .. side hot air mechanism (first hot air mechanism), 151. Air blower), 152... First heater (heater), 153... Side hot air chamber (air blower), 154... First suction port (air blower), 155. ), 200... Printer body, 211... Sheet remaining amount detection unit (sheet remaining amount detection means), 300... Control unit, P.

Claims (5)

A sheet feeding device capable of continuously feeding a sheet-like recording medium to a predetermined conveyance path,
A sheet storage portion for storing a sheet bundle composed of a plurality of sheet-like recording media;
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;
One end is rotatably supported by a rotation shaft, and the other end includes a push-up member that abuts against the bottom surface of the sheet placement plate and pushes up the sheet placement plate. By rotating a member, the sheet placement plate is positioned between a sheet feeding position where the upper surface of the sheet bundle contacts the pickup roller and a separated position where the upper surface of the sheet bundle is separated from the pickup roller by a certain distance. Elevating mechanism for displacing,
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;
Sheet remaining amount detecting means for detecting the amount of the sheet-like recording medium loaded on the sheet placing plate;
A control unit for controlling the lifting drive of the lifting mechanism,
The control unit controls the raising / lowering drive of the raising / lowering mechanism so that the sheet placing plate is displaced between the paper feeding position and the separation position during the hot air blowing operation by the first hot air mechanism. The lifting mechanism is controlled so as to change the amount of rotation of the rotating shaft in the separating operation according to the amount of sheet-like recording medium detected by the remaining sheet detecting means. apparatus. The rotation shaft is a drive shaft, and the lifting mechanism drives the drive shaft to rotate the push-up member, thereby moving the sheet placement plate between the sheet feeding position and the separation position. Configured to displace,
The control unit controls the elevating mechanism so as to change the rotation amount of the drive shaft in the separation operation according to the amount of sheet-like recording medium detected by the sheet remaining amount detection unit. Paper feeding device to be used. A storage unit for storing a descent drive time of the elevating mechanism according to the amount of the sheet-like recording medium;
A timer for measuring a descent drive time read from the storage unit from the start of descent drive of the elevating mechanism,
The control unit reads the descent driving time corresponding to the amount of the sheet-like recording medium from the storage unit based on the detection result of the sheet remaining amount detecting unit, and the timer measures the descent driving time. 3. The sheet feeding device according to claim 1, wherein the lowering drive of the elevating mechanism is controlled so as to rotate the rotation shaft until it is. The elevating mechanism includes a stepping motor that rotates the drive shaft forward and backward,
The number of lowering drive steps of the stepping motor corresponding to the amount of the sheet-like recording medium is stored in the storage unit,
The control unit reads out the number of lowering drive steps of the stepping motor corresponding to the amount of the sheet-like recording medium from the storage unit based on the detection result of the remaining sheet amount detecting unit, and only the number of lowering driving steps The sheet feeding device according to claim 2, wherein the lowering drive of the lifting mechanism is controlled so as to rotate the stepping motor. A paper feeding device according to any one of claims 1 to 4,
An image forming apparatus comprising: an image forming apparatus main body that forms an image on a sheet-like recording medium fed from the paper feeding apparatus.

Images