JP2008303007A - Paper feeder, image forming device and sheet tension slacking method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a paper feeder capable of preventing or suppressing the tension noise and the rattle noise when feeding sheets to the image forming position without reducing the deflection of the sheets before feeding the sheets, a printer such as a stencil printer having the paper feeder, an image forming device such as a copier, a facsimile, and a printer, and a sheet tension slacking method using the same. <P>SOLUTION: The paper feeder 52 comprises a feeding member 83 for feeding sheets P to an image forming position N, and a conveying member 32 for conveying the sheets P toward the feeding member 83, forms the deflection in the sheets P between the feeding member 83 and the conveying member 32, and feeds the sheets P to the image forming position N while eliminating the deflection of the sheets P by the feeding member 83. The paper feeder has a shock-absorbing means 36 for absorbing the tension of the sheets P caused by the elimination of the deflection of the sheets P. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention includes a paper feeding device that is provided in a printing device such as a stencil printing device, an image forming device such as a copying machine, a facsimile machine, and a printer, and that feeds a sheet such as paper on which image formation is performed to an image forming position. The present invention also relates to such an image forming apparatus and a sheet tension buffering method using them.

  Conventionally, as described in [Patent Document 1] to [Patent Document 3] and the like, such a sheet feeding device is directed to a registration roller that feeds a sheet to an image forming position at a predetermined timing, and a registration roller. A conveying roller that conveys the sheet and a guide member that is disposed between these rollers and guides the sheet toward the registration roller. In order to eliminate the skew of the sheet, the registration of the sheet leading end is stopped. The sheet is further conveyed toward the registration roller by the conveying roller in a state of being abutted against the roller, and the sheet is bent. The image forming position corresponds to a region where the plate cylinder and the press roller face each other in a printing apparatus, and a transfer region in a copying machine using a latent image carrier.

  Since the registration roller rapidly sends the sheet to the image forming position after the sheet is bent, when the sheet is stretched, a sheet noise or a tapping sound of the sheet hitting the guide member is generated. Since these sounds are generated every time an image is formed on a sheet and can be a noise, it is important to prevent or suppress these sounds.

  Therefore, in [Patent Document 1], after the sheet is bent to cancel the skew, and before feeding to the image forming position, the registration roller is driven to clamp the leading end portion of the sheet, thereby bending the sheet. There has been proposed a technique for reducing the noise and the beating sound when the paper is rapidly sent to the image forming position. [Patent Document 2] proposes a technique for promoting the formation of the sheet deflection, and [Patent Document 3] proposes a technique for reducing the sound generated when the sheet deflection is formed. .

JP 2002-173254 A JP 59-194946 A JP-A-11-322136

  However, the technique described in [Patent Document 1] employs this technique because it takes time to drive the registration roller so as to sandwich the leading end portion of the sheet between the registration rollers after eliminating the skew of the sheet. In the image forming apparatus, this technique may become a bottleneck, and there is a possibility that the increase in the image forming speed may be limited.

  The present invention relates to a sheet feeding device that prevents or suppresses a squealing or tapping noise when feeding a sheet to an image forming position without reducing the deflection of the sheet before feeding the sheet, and stencil printing provided with the same. It is an object of the present invention to provide a printing apparatus such as an apparatus, an image forming apparatus such as a copying machine, a facsimile machine, and a printer, and a sheet tension buffering method using them.

  In order to achieve the above object, the invention described in claim 1 includes a feeding member that feeds a sheet to an image forming position, and a conveying member that conveys the sheet toward the feeding member. In a sheet feeding device that forms a sheet bend between a member and the conveying member and then feeds the sheet to an image forming position while eliminating the sheet bend by the feeding member. By eliminating the sheet bend It has a buffering means for buffering the tension of the sheet.

  According to a second aspect of the present invention, in the paper feeding device according to the first aspect, the buffer means includes a gas sending means for sending a gas toward the sheet when the bending of the sheet is eliminated. To do.

  According to a third aspect of the present invention, in the paper feeding device according to the second aspect, the sheet conveyed toward the feeding member by the conveying member between the feeding member and the conveying member is supported from below. It has a support member, The support member has a hole for letting the gas sent out towards the sheet by the gas sending means pass.

  According to a fourth aspect of the present invention, in the paper feeding device according to the second or third aspect, the gas delivery means jets the gas toward the sheet by compressing the gas and releasing the compressed gas. It is characterized by that.

  According to a fifth aspect of the present invention, in the paper feeding device according to any one of the first to fourth aspects, the buffer means includes an elastic body that engages with the sheet when the bending of the sheet is eliminated, It has the elastic body drive means which drives this elastic body, It is characterized by the above-mentioned.

  According to a sixth aspect of the present invention, in the paper feeding device according to the fifth aspect, the sheet conveyed toward the feeding member by the conveying member between the feeding member and the conveying member is supported from below. It has a support member, and the support member has a hole for allowing the elastic body to be driven when the elastic body engaging means engages the elastic body with a sheet.

  The invention according to claim 7 is the paper feeding device according to claim 5 or 6, wherein the elastic body driving means includes the feeding member, and drives the elastic body in synchronization with the driving of the feeding member. It is characterized by doing.

  According to an eighth aspect of the present invention, there is provided an image forming apparatus comprising the paper feeding device according to any one of the first to seventh aspects.

  According to a ninth aspect of the invention, there is provided a sheet tension buffering method for buffering a sheet tension by using the paper feeding device according to any one of the first to seventh aspects or the image forming apparatus according to the eighth aspect.

  The present invention includes a feeding member that feeds a sheet to an image forming position, and a conveying member that conveys the sheet toward the feeding member, and the sheet is disposed between the feeding member and the conveying member. In the sheet feeding device that feeds a sheet to an image forming position while eliminating the deflection of the sheet by the feeding member after forming the deflection, a buffering unit for buffering the tension of the sheet due to the cancellation of the bending of the sheet To provide a sheet feeding device that can prevent or suppress the noise and tapping noise when feeding a sheet to an image forming position by buffering the sheet tension, and that improves the operator's feeling of use. Can do.

  If the buffer means has gas sending means for sending gas toward the sheet when the bending of the sheet is eliminated, the sheet is brought into the image forming position by buffering the tension of the sheet by sending the gas. It is possible to provide a paper feeding device that can prevent or suppress the noise and tapping noise when feeding, and that improves the usability of the operator.

  A support member configured to support a sheet conveyed by the conveying member toward the feeding member from below between the feeding member and the conveying member; If there is a hole through which the gas to be sent out passes, the sheet can be transported well by the support member, and the sheet is fed to the image forming position by buffering the tension of the sheet by sending out the gas from the hole. It is possible to provide a paper feeding device that can prevent or suppress the noise and tapping noise during feeding and improve the operator's feeling of use.

  Assuming that the gas delivery means is configured to eject the gas toward the sheet by compressing the gas and releasing the compressed gas, the gas ejection using the gas delivery means having relatively high versatility. Due to the buffering of the sheet tension caused by the sheet feeding, it is possible to prevent or suppress the tension sound and the tapping sound when the sheet is fed to the image forming position, and it is possible to provide a sheet feeding device that improves the usability of the operator. .

  If the buffer means includes an elastic body that engages with the sheet when the bending of the sheet is eliminated, and an elastic body driving means that drives the elastic body, With the buffering of the sheet tension, it is possible to prevent or suppress the tension sound and tapping sound when the sheet is fed to the image forming position, and it is possible to provide a sheet feeding device with improved operator feeling.

  A support member configured to support a sheet conveyed by the conveying member toward the feeding member from below between the feeding member and the conveying member; If the elastic body is provided with a hole for allowing the elastic body to be driven when the elastic body is engaged with the sheet, the conveyance of the sheet is improved by the support member and the driving is permitted by the hole. Due to the cushioning of the sheet tension due to the engagement of the elastic body with the sheet, it is possible to prevent or suppress the tension sound and tapping sound when feeding the sheet to the image forming position, improving the operator's feeling of use. A paper feeding device can be provided.

  If the elastic body driving means has the feeding member and drives the elastic body in synchronism with the driving of the feeding member, the elastic body is driven by engagement of the elastic body that is driven in a timely manner. By cushioning the sheet tension, it is possible to better prevent or control the tension and tapping noise when feeding the sheet to the image forming position, improving the operator's feeling of use and driving the elastic body. By omitting the drive source unique to the means, it is possible to simplify the configuration, and it is possible to provide a paper feeding device that can be reduced in price and reduced in size.

  The present invention resides in an image forming apparatus having the sheet feeding device according to any one of claims 1 to 7, and has a sheet feeding device that exhibits any of the above-described effects, and cushions the sheet tension. As a result, it is possible to prevent or suppress the squeaking and tapping noises when feeding the sheet to the image forming position, and to provide an image forming apparatus with an improved usability for the operator.

  The present invention is a sheet tension buffering method for cushioning a sheet tension by using the sheet feeding device according to any one of claims 1 to 7 or the image forming apparatus according to claim 8. A sheet feeding device having any of the above effects or an image forming apparatus that sends the above-described effects is provided, and the tension or tapping noise when feeding the sheet to the image forming position is prevented by buffering the sheet tension. A sheet tension buffering method that can be suppressed can be provided.

  FIG. 1 shows an outline of a heat sensitive digital plate-making integrated stencil printing apparatus which is a printing apparatus as an image forming apparatus to which the present invention is applied. The stencil printing apparatus 100 includes an image scanner 61 serving as a document reading unit as a document reading unit for reading a document image on the upper portion of the apparatus main body 67. The image scanner 61 includes a carriage 60 having a lamp 63 for illuminating a document set on a contact glass 62, a plurality of mirrors 64, an imaging lens 65, a one-dimensional array CCD 66, and the like. ing.

  The stencil printing apparatus 100 has a master roll 70a in the form of a roll formed at the lower part of the image scanner 61, a printing unit 69 centered on a rotatable plate cylinder 68 and an unused master 70 made of heat-sensitive stencil paper. A plate making apparatus 71 is provided as a plate making means as a plate making unit which is built in a replaceable manner and punches the master 70 drawn from the master roll 70a and supplies the master 70 which has been made to the plate cylinder 68.

  The stencil printing apparatus 100 also has a press roller 20 as a pressing body for pressing a printing paper P as a sheet to be fed toward the outer periphery of the printing drum 68 toward the printing drum 68, and the printing paper from the printing drum 68. A peeling claw 75 that can freely advance and retreat P and a plate discharging device 76 that is a plate discharging means for peeling the used master 70 wound around the plate cylinder 68 before the printing process are provided.

  The stencil printing apparatus 100 also includes a paper feeding device 52 that feeds the printing paper P toward the printing unit 69 and a paper transporting device that transports the printing paper P peeled from the plate cylinder 68 by the peeling claw 75. 84, a paper discharge tray 85 as a paper discharge tray on which the printed printing paper P conveyed by the paper conveyance device 84 is stacked, the ink supply device 10 mainly located inside the plate cylinder 68, and the plate cylinder And a main motor 11 as a drive motor as drive means.

  The stencil printing apparatus 100 also includes a pressing body displacing means 22 that displaces the press roller 20 toward the plate cylinder 68 and holds the press roller 20 at a position separated from the plate cylinder 68, and an operator such as a user, that is, an operator, performs stencil printing. An operation panel (not shown) for operating the apparatus 100 and a control unit as control means (not shown) for controlling the overall operation of the stencil printing apparatus 100 are provided.

  The plate cylinder 68 is a porous support cylinder (not shown) provided with a clamp device 73 for gripping the end of the master 70 that has been made, and an opening (not shown) and a non-opening (not shown). A multi-layer mesh screen (not shown) that is a resin or metal mesh covering the outer periphery of the porous support cylinder, and drum flanges (not shown) fixed to both ends of the porous support cylinder. It is connected to the main motor 11 through a gear train that does not.

  The opening of the porous support cylindrical body is a portion in which a large number of small holes for allowing the ink supplied by the ink supply device 10 to pass therethrough, and the transmitted ink is configured to ooze out from the mesh screen. Yes.

  Each drum flange is rotatably supported by a drum shaft 25 as an ink supply pipe which is an ink supply shaft. The drum shaft 25 is supported by a main body side plate (not shown) of the apparatus main body 67. Therefore, the plate cylinder 68 is rotatably supported by the drum shaft 25 by the drum flange.

  The plate cylinder 68 is integrated with the gear 12 having the drum shaft 25 as the rotation center. The main motor 11 is a stepping motor, and is fixed to the main body side plate and has a gear 13 that meshes with the gear 12. Therefore, the plate cylinder 68 is rotationally driven by the main motor 11. The plate cylinder 68 is driven to rotate in the clockwise direction in FIG.

  The clamp device 73 is disposed in a non-opening portion other than the mesh screen of the porous support cylindrical body along one of the bus bars of the plate cylinder 68, and the stage 14 made of a magnetic material and the stage 14 It has a clamper 42 that opens and closes and that clamps the tip of the master 70 with the stage 14 to which a magnet or the like is attached.

  The clamp device 73 is also arranged in parallel with the stage 14 in the direction perpendicular to the paper surface in FIG. 1, and forms a center of rotation of the clamper 42. In the position, an opening / closing device (not shown) that opens and closes the stage 14 is provided.

  The ink supply device 10 is disposed so as to face the inner peripheral surface of the plate cylinder 68 and supplies the ink 15 to the plate cylinder 68. The ink supply device 10 faces the ink roller 16 and has a slight gap in the ink roller 16. A doctor roller 18 that forms a wedge-shaped space with the ink roller 16 and forms an ink reservoir 17 in the wedge-shaped space; a drum shaft 25 that drops and supplies the ink 15 to the ink reservoir 17; And a pair of ink roller side plates (not shown) that rotatably support the ink roller 16 and the doctor roller 18 therebetween.

  Although not shown, the ink supply device 10 supplies an ink pack connected to one end of the drum shaft 25 and located outside the plate cylinder 68 and ink in the ink pack toward the drum shaft 25. An ink pump located outside the plate cylinder 68, an ink sensor for detecting the amount of ink in the ink reservoir 17, and the driving force of the main motor 11 are transmitted to the ink roller 16 and the doctor roller 18, and the ink roller 16 and the doctor roller 18 are transferred to the plate. A driving force transmission mechanism constituted by gears, belts, and the like that is driven to rotate in the same direction as the plate cylinder 68 in synchronization with the cylinder 68.

  The drum shaft 25 is formed with a plurality of holes 25a as supply holes which are ink dropping holes in the axial direction, and has a function of an ink supply pipe. The drum shaft 25 has an ink roller side plate fixed to both ends thereof.

  The ink roller 16 has an ink roller shaft 21 that forms the center of rotation, and the ink roller shaft 21 is rotatably supported at both ends by an ink roller side plate. The doctor roller 18 is also rotatably supported on the ink roller side plate in the same manner as the ink roller 16.

  Accordingly, the ink roller 16 and the doctor roller 18 rotate to knead and extend the ink 15 in the ink reservoir 17, and the ink 15 in the ink reservoir 17 extends from between the ink roller 16 and the doctor roller 18 to the outer surface of the ink roller 16. After that, the ink is supplied to the inner peripheral surface of the plate cylinder 68.

The ink 15 supplied to the inner peripheral surface of the plate cylinder 68 oozes out to the outer peripheral surface of the plate cylinder 68 through the porous support cylindrical body and a plurality of layers of mesh screens.
When it is detected that the ink 15 has been consumed and the amount of ink in the ink reservoir 17 has been reduced by the ink sensor, the ink in the ink pack is sucked by the ink pump, and from the plurality of holes formed in the drum shaft 25, the ink reservoir 17 is supplied.

  The press roller 20 is located below the plate cylinder 68. The press roller 20 includes a cored bar and nitrile rubber or chloroprene rubber as an elastic body that is formed in a cylindrical shape and is mounted around the cored bar.

  The press roller 20 is displaced toward the plate cylinder 68 at a predetermined timing by the pressing body displacing means 22, and the printing paper P is fed to the plate cylinder 68 at the nip portion N as an image forming position that is a portion facing the plate cylinder 68. The ink is pressed against the master 70 wound around the plate cylinder 68 by being pressed toward the printing cylinder 68, and the ink oozing from the master 70 is adhered to the printing paper P to perform printing.

  The master 70 attached to the plate making apparatus 71 is made of a thermoplastic resin film having a thickness of approximately 1 to 3 μm and a paper sheet, synthetic fiber, or a mixture of Japanese paper fiber and synthetic fiber, which is a support sheet of a porous support. Laminated laminate structure.

  The plate making apparatus 71 includes a master flange 88 as a holder means for holding the master roll 70a rotatably and guiding the conveyance of the master 70 fed out from the master roll 70a, and a roller pair 89 for pulling out the master 70 from the master roll 70a. The platen roller 77 further conveys the master 70 drawn out by the roller pair 89, and a thermal head 78 that is a perforating member as a plate-making head disposed opposite to the platen roller 77.

  The plate making apparatus 71 also includes a cutter 80 that cuts the master 70 that has been made into a predetermined length, a roller pair 79 that transports the master 70 that has been punched by the thermal head 78 toward the plate cylinder 68, and A guide plate 74 that guides the master 70 that has been subjected to plate making toward the plate cylinder 68 is provided.

  Although not shown, the plate making apparatus 71 also includes a master conveyance drive motor that is a stepping motor that rotationally drives the roller pair 89 and 79, and a pair of plate making unit side plates that rotatably support the platen roller 77 therebetween. Yes.

  The master roll 70a is obtained by winding the master 70 around a roll core 37 that is a winding core as a winding member, and the master flange 88 holds the roll core 37 detachably and rotatably. Thus, the master roll 70a is held detachably and rotatably about the roll core 37.

  The thermal head 78 has a heat generating portion constituted by an infinite number of heat generating elements along a direction perpendicular to the paper surface of FIG. The thermoplastic resin film of the master 70 is located on the thermal head 78 side, and the thermal head 78 melts the thermoplastic resin film portion of the master 70 conveyed by the roller pairs 89 and 79 and the platen roller 77 by the heat generating portion. It comes to pierce. Each heating element constituting the heating unit generates heat by energization, and energization control to each heating element is performed by the control unit 90.

  The roller pairs 89 and 79 are rotatably supported between the plate making unit side plates while being in pressure contact with each other. The master conveyance drive motor is configured to rotationally drive the roller pairs 89 and 79 by energization. The energization control to the master conveyance drive motor is performed by the control unit 90.

  The conveyance speed of the master 70 by the roller pair 79 is set to be higher than the conveyance speed of the master 70 by the platen roller 77, and a predetermined tension is applied to the master 70 while causing a slip with the master 70. ing. The cutter 80 is provided with guillotine type upper and lower blades in this embodiment, but may be a rotary blade moving type rotary type or the like. The guide plate 74 is fixed between the plate making unit side plates.

  In the thermal head 78, the heating element generates heat based on image data based on the original read by the image scanner 61 and other image data input from an external device such as a personal computer, and the master 70 is punched.

  The plate removal device 76 peels off the master 70 from the plate cylinder 68 and conveys it, and the plate removal box 54 that stores the used master 70 that has been peeled off and conveyed from the plate cylinder 68 by the master peeling device 53. And have.

  As shown in FIG. 1 or FIG. 2, the paper feeding device 52 is provided so as to be movable up and down, a paper feed base 81 on which the print paper P is stacked, and a paper feed device 81 that is disposed above the paper feed base 81 and stacked on the paper discharge base 81. A paper feed roller 82 as a calling roller for feeding out and feeding out the printed paper P, and a separation feeding means 31 for separating and feeding the print paper P on the paper feed table 81 fed out by the paper feed roller 82 into one sheet have.

  The paper feeding device 52 is also driven in synchronization with the rotation of the plate cylinder 68, and a registration roller pair 83 as a feeding member that feeds the printing paper P fed by the separation feeding means 31 to the nip portion N; An upper guide plate that guides the printing paper P fed out by the separation feeding unit 31 to the registration roller pair 83 and guides the printing paper P fed from the registration roller pair 83 toward the nip portion N to the nip portion N. 40, the lower guide plate 41, an air pump 36 as a buffering means disposed between the separating and feeding means 31 and the registration roller pair 83, and a paper detection device (not shown).

  The paper feed roller 82 is driven to rotate in the clockwise direction in the figure at a fixed position. The paper feed table 81 is controlled to rise and fall according to the number and thickness of the printing paper P so that the uppermost printing paper P contacts the paper feeding roller 82.

  As shown in FIG. 2, the separation feeding unit 31 is rotated between the separation roller 32 as a conveying member that is driven to rotate clockwise in the drawing and conveys the printing paper P toward the registration roller pair 83, and the separation roller 32. The separation pad 33 for separating the printing paper P, the spring 34 that urges the separation pad 33 toward the separation roller 32, and the hole 35a through which the separation pad 33 is inserted, and the separation pad 33 is separated through the hole 35a. A front plate 35 is provided for advancing and retracting the roller 32 and guiding the printing paper P toward the guide plate 40.

  The registration roller pair 83 includes an upper feed roller 37 and a lower feed roller 38, and feeds the printing paper P to the nip portion N at a predetermined timing when the image area of the master 70 enters the nip portion N. The upper feed roller 37 and the lower feed roller 38 rotate about the rotation shafts 37a and 38a, respectively. The rotary shaft 38a is driven to rotate counterclockwise in the figure by a motor as a drive source (not shown). The rotating shaft 37a is rotatably supported on a side plate (not shown).

  The upper guide plate 40 and the lower guide plate 41 have holes (not shown) through which the upper feed roller 37 and the lower feed roller 38 are inserted, respectively, and the registration roller pair 83 has a nip between the upper guide plate 40 and the lower guide plate 41. Is forming.

The lower guide plate 41 is a support section as a support member that supports the printing paper P conveyed from the lower side by the separation roller 32 toward the registration roller 83 on the upstream side of the upper guide plate 41 in the conveyance direction of the printing paper P. 39.
The support portion 39 has a hole 39a that allows the lower surface side and the upper surface side to communicate with each other.

  The air pump 36 is located below the support portion 39, and has a delivery portion 36a constituted by a pipe communicating with the hole 39a. The air pump 36 compresses gas, that is, air, and releases the compressed air, thereby ejecting air from the delivery unit 36a. The ejected air is sent out above the support portion 39 through the hole 39a.

  Each of the sheet feed table 81, the sheet feed roller 82, the separation roller 32, the air pump 36, and the registration roller pair 83 is driven by the control unit in association with each other.

  That is, the paper feed table 31 is driven so that the uppermost printing paper P contacts the paper feed roller 82. The paper feed roller 82 is driven in a state where the uppermost printing paper P is in contact therewith.

  The separation roller 32 is driven to separate the printing paper P conveyed by the paper feed roller 82 into one sheet, and the leading edge of the printing paper P being conveyed is synchronized with the rotation of the plate cylinder 68. 2, the printing paper P is further driven to further convey the printing paper P in order to eliminate the skew of the printing paper P, in other words, the skew, even after hitting the resist roller pair 83 that is in a stopped state, as shown in FIG. In addition, the printing paper P is buckled upward between the separation roller 32 and the registration roller pair 83 to form a bend. The bending is mainly formed above the support portion 39, and this is eliminated when the printing paper P is skewed due to the formation of the bending.

  The registration roller pair 83 is driven at a timing synchronized with the rotation of the plate cylinder 68 after the deflection of the printing paper P is formed, and the printing paper P is directed toward the nip portion N while eliminating the deflection of the printing paper P. And send it out. This feeding is abruptly performed so as to match the rotational speed of the plate cylinder 68.

  In this way, when the registration roller pair 83 rapidly sends the printing paper P, the printing paper P is subjected to an action in which the bending is eliminated and the printing paper P is stretched. At this time, if only the action applied to the printing paper P occurs, there is a risk that a tension sound of the printing paper P or a tapping noise that the printing paper P strikes the lower guide plate 41 and the front plate 35, particularly the support portion 39 may occur. However, when the registration roller pair 83 is driven, the air pump 36 ejects air toward the lower surface of the printing paper P, that is, the surface opposite to the direction in which the bending is formed, so that the movement of the printing paper P is eliminated. The abrupt tension of the printing paper P due to the reduction of energy and the elimination of the bending of the printing paper P is buffered, and such tensioning and tapping noises are suppressed or prevented.

  Therefore, the air pump 36 starts the air compression operation when the leading edge of the printing paper P hits the registration roller pair 83. Note that the air ejection timing by the air pump 36 may be from the start of driving the registration roller pair 83 until the elimination of the bending of the printing paper P is completed as long as the sound is suppressed or prevented. The start timing of the air compressing operation of the printing paper P is a timing at which the required air compression is completed before the ejection.

  In this way, the air pump 36 sends out air toward the printing paper P when the bending of the printing paper P is eliminated in order to buffer the tension of the printing paper P due to the elimination of the bending of the printing paper P. It functions as a means. Since the air pump 36 sends air to a position where the bending of the printing paper P is maximum, such a buffering effect is effectively exhibited. In particular, the air pump 36 functions as a gas ejection means as a gas delivery means because the air is delivered in the form of ejection called compressed air delivery.

  The ejection of the air from the air pump 36 and the compression of the air for that purpose, which are performed for buffering the sound, do not need to be performed separately, so that the increase in the printing speed is not suppressed. As the gas delivery means, a fan or the like may be used as long as it has performance such as output and responsiveness sufficient to suppress or eliminate such sound.

The paper conveying device 84 includes a driving roller 55 and a driven roller 56, a conveying belt 58 as a paper discharge belt wound around the driving roller 55 and the driven roller 56, and an adsorption for adsorbing the printing paper P on the conveying belt 58. And a fan 57.
The paper discharge table 85 is for discharging the print paper P after printing by the printing unit 69 and holding the print paper P in a stacked manner.

  The operation panel includes an operation key for performing an operation necessary for printing by the stencil printing apparatus 100, and a display unit for performing display for notifying the operator of the state of the stencil printing apparatus 100.

The display unit is a touch panel type liquid crystal display panel, and displays the state of the stencil printing apparatus 100.
The operation keys include a plate making start key for inputting a plate making start command signal for starting plate making in the plate making apparatus 71, and a numeric keypad for inputting numbers such as the number of printed sheets.

  The control unit includes a CPU, a ROM that stores an operation program of the stencil printing apparatus 100 and various data necessary for the operation of the operation program, a RAM that stores data necessary for the operation of the stencil printing apparatus 100, and the like. It has become.

  The ROM stores a sheet tension buffering program that causes the buffering unit, that is, the air pump 36, to perform the above-described operation in order to suppress or eliminate the above-described sound in the sheet feeding device 52.

  A series of printing operations of the entire stencil printing apparatus 100 will be described.

  When an operator sets a document on the image scanner 61 and presses a plate-making start key, for example, when a plate-making start command signal is issued, the image scanner 61 starts reading the document and the main motor 11 starts the plate. The cylinder 68 is rotationally driven in the clockwise direction in FIG. 1, and in this process, a used master (not shown) is separated from the plate cylinder 68 by the plate discharging device 76 and discarded.

  The plate cylinder 68 is further rotated, and then stops when the clamping device 73 occupies the substantially right end position in FIG. When the plate cylinder 68 stops, the clamper 42 is released by the opening / closing device, and the plate feed standby state is entered.

  On the other hand, plate making to the master 70 is performed by the plate making apparatus 71 according to the image information read by the image scanner 61. The master 70 may be made based on image data input from an external device.

  When the platen roller 77 and the roller pairs 89 and 79 are rotated and the master 70 is conveyed by one line in the sub-scanning direction, the master 70 is made by specifying the thermal head 78 in accordance with the image information constituted by the image data. A voltage is applied in a pulse form to the resistance heating element, and the thermoplastic resin film constituting the master 70 is heated and perforated, and plate making is performed by dot formation in the main scanning direction.

  The master 70 that has been made in this manner is sent out toward the plate cylinder 68 by the roller pair 79 and is guided by the guide plate 74, and the tip of the master 70 enters between the stage 14 and the clamper 42. When it is determined by the number of pulses of the master conveyance drive motor that the tip of the master 70 has reached the stage 14, the clamper 42 is closed by the opening / closing device, and the tip of the master 70 is clamped by the clamp device 73.

  When the clamper 42 is closed, the rotational drive of the plate cylinder 68 is resumed. The rotational speed of the plate cylinder 68 is the same as the conveying speed of the master 70. Due to the rotation of the plate cylinder 68, the master 70 which has been subjected to plate making is wound around the outer peripheral surface of the plate cylinder 68 so as to cover the opening of the porous support cylindrical body provided in the plate cylinder 68.

  When it is determined that the plate making is completed based on the number of pulses of the master conveying motor, the cutter 80 is operated to cut the master 70, the rotational driving of the platen roller 78 and the roller pairs 89 and 79 is stopped, and the cut master 70 is cut. Is pulled out to the plate cylinder 68 as the plate cylinder 68 rotates, and the winding around the plate cylinder 68 is completed.

  Thereafter, the printing process is executed. The uppermost printing paper P of the paper feed table 81 is fed by the paper feeding roller 82, and the leading edge of the printing paper P comes into contact with the nip portion of the resist roller pair 83 in a stopped state to align the leading edge.

  The registration roller pair 83 is driven in synchronization with the rotation of the plate cylinder 68 to feed the printing paper P to the nip portion N. At this time, by driving the air pump 36 as described above, the above-described tension sound and tapping sound are suppressed or prevented.

  The press roller 20 is displaced upward by the pressing body displacing means 22 on the condition that the front end of the printing paper P has reached the vicinity of the nip N between the plate cylinder 68 and the press roller 20. Then, by continuously pressing the printing paper P against the master 70 on the plate cylinder 68 by the press roller 20, the ink in the plate cylinder 68 oozes out from the perforated portion of the master 70 and is wound around the plate cylinder 68. The master 70 comes into close contact with the plate cylinder 68 and is transferred to the printing paper P to perform printing.

  The printing paper P after printing is peeled off from the plate cylinder 68 by the peeling claw 75, guided to the paper transport device 84 as the plate cylinder 68 rotates, and discharged from the paper transport device 84 to the paper discharge tray 85 for loading. Is done.

  The printing process is repeated until the printing of the number of prints set with the numeric keypad is completed, and each time the printing process is performed, the registration roller pair 83 is driven and the printing paper P is fed to the nip portion N. Since the air pump 36 is driven as described above, noise due to the above-described tension and hitting noise is suppressed or prevented in the printing process.

FIG. 3 shows a paper feeding device 52 in which the buffer means has another form. In the sheet feeding device 52, the same components as those illustrated in FIG. 2 are denoted by the same reference numerals, and description thereof is omitted as appropriate.
The sheet feeding device 52 shown in FIG. 3 includes, as a buffering means, a cam-shaped sponge 91 as an elastic body that engages with the printing paper P in a manner to contact the printing paper P when the bending of the printing paper P is eliminated, and the sponge 91. Elastic body driving means 92 for rotationally driving.

  The elastic body driving means 92 includes a lower feed roller 38 having a rotation shaft 38 a, a rotation shaft 93 of a sponge 91 that is rotatably disposed below the support portion 39, a rotation shaft 38 a, and a rotation shaft 93. It has an endless belt 94 wound around and a motor (not shown) that drives the rotary shaft 38a to rotate. The rotary shaft 38a and the rotary shaft 93 have the same diameter, and the lower feed roller 38 and the sponge 91 rotate in a 1: 1 ratio in synchronization.

  The sponge 91 has a large diameter portion and a small diameter portion. The hole 39a is formed so that the large diameter portion enters as shown in FIG. 3 when the sponge 91 is rotated by the rotation of the rotary shaft 93 and the large diameter portion faces the support portion 39 side. Therefore, even if the sponge 91 rotates, it does not come into contact with the support portion 39. Thus, the hole 39a allows the sponge 91 to be driven by the elastic body driving means 92. When the large diameter portion enters the hole 39a, the large diameter portion projects to the upper surface side of the support portion 39, as shown in FIG.

  In the paper feeding device 52 having such a configuration, when the registration roller pair 83 suddenly sends the printing paper P, the printing paper P is subjected to an action to bend and extend, but at this time, it synchronizes with the driving of the registration roller pair 83. As a result, the sponge 91 rotates, and the large diameter portion enters the upper surface of the support portion 39 and comes into contact with the lower surface of the printing paper P receiving such an action, that is, the surface opposite to the direction in which the deflection is formed.

  As a result, the kinetic energy of the printing paper P, which is free from bending, is reduced, and the sudden tension of the printing paper P due to the elimination of the bending of the printing paper P is buffered, thereby suppressing or preventing the squeaking noise and tapping noise. Is done.

  When the cam 91 of the sponge 91 and the phase of rotation are brought into contact with the printing paper P so as to reduce such sound, the position of the sponge 91 with respect to the printing paper P is adjusted so that the bending of the printing paper P is eliminated. The sponge 91 is configured to move in the direction so as to smoothly contact the printing paper P. In addition, since the cam 91 and the rotation phase are engaged with the sponge 91 at a position where the bending of the printing paper P is maximum, such a buffering effect is effectively exhibited.

  In FIG. 3, the large-diameter portion enters the hole 39a in a state where the printing paper P is greatly bent, but actually, as described above, the large-diameter portion enters the hole 39a. This is when the bending of the printing paper P is being eliminated.

  The driving of the sponge 91 that is performed for buffering the sound does not need to be performed separately, so that the increase in the printing speed is not suppressed. Since the drive of the sponge 91 is obtained from the lower feed roller 38, a new drive source is not required, the cost is suppressed, and the drive of the sponge 91 is performed in synchronization with the lower feed roller 38. The sound is suppressed or prevented by always contacting the printing paper P in a timely manner.

  The material of the elastic body is not limited to a sponge but may be any material having a desired function such as soft rubber or film. The elastic body does not necessarily need to be rotationally driven. When the support unit 39 guides the printing paper P to the registration roller 83 so as to come into contact with the printing paper P whose bending is being eliminated, and before the bending is formed, It may be driven so as to occupy a position where it does not engage with the printing paper P. For example, it may be driven up and down so as to advance and retreat into the hole 39a.

  It should be noted that the support unit 39 should occupy a position where it does not engage the printing paper P when guiding the printing paper P to the registration roller 83 before the deflection is formed under the condition that the buffer means should satisfy. The same applies to the gas delivery means.

  The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the specific embodiments, and the present invention described in the claims is not specifically limited by the above description. Various modifications and changes are possible within the scope of the above.

  For example, the sheet feeding device may have both the buffer unit shown in FIG. 2 and the buffer unit shown in FIG. The separation roller 32 is not always necessary, and when the separation roller 32 is omitted, the paper feed roller 82 becomes a conveying member. That is, a member that conveys a sheet toward the feeding member and forms a sheet deflection with the feeding member, such as positioned immediately upstream of the feeding member in the sheet conveyance direction, is the conveyance member.

  In each of the above-described embodiments, since the sheet is bent upward, the gas sent out by the gas sending means is blown to the lower surface side of the sheet, and the elastic body is in contact with the lower surface side of the sheet. The surface of the sheet with which the elastic body abuts may be a surface opposite to the direction in which the deflection is formed, and in a configuration in which the deflection of the sheet is formed below, the gas delivered by the gas delivery means is on the upper surface side of the sheet The elastic body comes into contact with the upper surface side of the sheet.

  The image forming apparatus to which the present invention is applied is a stencil printing apparatus in the above-described form, but it may be a printing apparatus having another configuration, and is not a printing apparatus but a copying machine, a facsimile, a printer, or the like. It may be an image forming apparatus such as a multifunction peripheral. In an image forming apparatus that forms an image using a latent image carrier, an image forming position where a feeding member feeds a sheet includes a transfer region and a transfer position of an image formed on the latent image carrier. Become.

  When the image forming apparatus is a stencil printing apparatus, a plurality of plate cylinders may be provided. For example, color printing may be performed using a plurality of plate cylinders. The pressing body may be an impression cylinder instead of a press roller.

  Similarly, when the image forming apparatus uses a latent image carrier such as a photoconductor, a plurality of latent image carriers may be provided. For example, color printing is performed using a plurality of latent image carriers. It may be a thing.

In addition, the image forming apparatus may perform double-sided image formation by including a mechanism for reversing the sheet.
As a sheet used for image formation, in addition to plain paper generally used for copying and the like, OHP sheets, thick paper such as cards and postcards, recording media such as envelopes, and printing media can be used.

  The effects described in the embodiments of the present invention are only the most preferable effects resulting from the present invention, and the effects of the present invention are limited to those described in the embodiments of the present invention. is not.

1 is a front view illustrating an outline of a sheet feeding device to which the present invention is applied and an image forming apparatus including the same. FIG. 2 is a partially enlarged front view of the sheet feeding device illustrated in FIG. 1. It is a partially expanded front view of another example of a sheet feeding device to which the present invention is applied.

Explanation of symbols

32 Conveying member 36 Buffering means, gas delivery means 39 Support member 39a Hole 52 Paper feeding device 83 Feeding members 91, 92 Buffering means 91 Elastic body 92 Elastic body driving means 100 Printing device N Image forming position P Sheet

Claims (9)

A sheet feeding member that feeds the sheet to the image forming position; and a conveyance member that conveys the sheet toward the sheet feeding member, and the sheet is bent between the feeding member and the conveyance member. Thereafter, in the sheet feeding device that feeds the sheet to the image forming position while eliminating the bending of the sheet by the feeding member,
A sheet feeding device having buffering means for buffering sheet tension due to elimination of bending of the sheet. The paper feeding device according to claim 1.
The sheet feeding device according to claim 1, wherein the buffer means includes gas sending means for sending gas toward the sheet when the bending of the sheet is eliminated. The paper feeding device according to claim 2.
A supporting member that supports a sheet conveyed from the lower side by the conveying member toward the feeding member between the feeding member and the conveying member;
The sheet feeding device according to claim 1, wherein the support member has a hole through which the gas delivered by the gas delivery means toward the sheet is passed. The sheet feeding device according to claim 2 or 3,
The gas delivery unit is configured to compress the gas and release the compressed gas to eject the gas toward the sheet. The paper feeding device according to any one of claims 1 to 4,
The sheet feeding device, wherein the buffer means includes an elastic body that engages with the sheet when the bending of the sheet is eliminated, and an elastic body driving means that drives the elastic body. The sheet feeding device according to claim 5.
A supporting member that supports a sheet conveyed from the lower side by the conveying member toward the feeding member between the feeding member and the conveying member;
The sheet feeding device according to claim 1, wherein the support member has a hole for allowing the elastic body engaging means to drive the elastic body when the elastic body is engaged with the sheet. The sheet feeding device according to claim 5 or 6,
The elastic body driving unit includes the feeding member, and drives the elastic body in synchronization with the driving of the feeding member.   An image forming apparatus comprising the sheet feeding device according to claim 1.   A sheet tension buffering method for buffering a sheet tension using the sheet feeding device according to claim 1 or the image forming apparatus according to claim 8.

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