JP3740245B2 - Sheet feeding device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus for conveying a sheet such as paper in an image forming apparatus such as a copying apparatus or a laser printer, and in particular, special paper such as cardboard, postcard, or colored paper that cannot be fed by a paper feeder from a cassette of the main body of the image forming apparatus. The present invention relates to an improvement of a multi-manual feeding device provided mainly for the purpose of sending a message.
[0002]
[Prior art]
2. Description of the Related Art In recent years, image forming apparatuses, particularly electronic copying machines, have been able to copy paper of various sizes without changing the paper in the cassette as the number of feeding cassettes increases. Among papers used in Japan, the papers that are frequently used are A4, A3 or B4, B5, and white paper called plain paper is generally used. However, in addition to such general paper, the user has the opportunity to send paper such as postcards, colored paper, OHP paper, and second original drawing paper, and these papers are transported from a dedicated manual feeder. To do.
[0003]
The manual feeding device includes a single manual feeding device and a multi manual feeding device. Recently, a multi manual feeding device capable of setting a large number of papers at a time has been generally used.
[0004]
A copying machine as an example of an image forming apparatus targeted by the present invention will be described below. FIG. 7 is a sectional view of a copying machine to which the present invention is applied.
[0005]
In FIG. 7, the paper as the sheet 15 that is in the cassette 13 and is stacked by the intermediate plate 14 is pressed against the feeding roller 16 by the intermediate plate, and the upper sheet is separated by the feeding roller 16. It is conveyed to the registration roller 12. The registration roller in the vertical direction is adjusted by this registration roller. A document image placed on the document glass 17 is irradiated by an illumination lamp 18 and irradiated on a photosensitive drum 21 such as an electrophotographic photosensitive member through a mirror 19 and a lens 20 to form a latent image. The latent image is converted into a toner image by the developing device 22 using toner as a developer. The positions of the toner image and the paper are timed by the registration roller 12, and the toner image is transferred to an appropriate position on the paper by a transfer roller 23 as a transfer means. The transferred paper is further transported to a fixing device 25 by a transport means 24, and the toner image is heated and melted and fixed on the paper. Then, the paper is stacked on a paper discharge tray (not shown) by a paper discharge roller 26.
[0006]
Further, 8 is a tray of the multi-manual feeder, and an intermediate plate 9 is provided in the tray, as shown in FIG. 8, and the intermediate plate 9 is used to transfer the paper stacked on the tray at the front end of the tray. The top surface of the paper is brought into contact with the multi-feed roller 10 made of a friction material such as rubber. When the paper is urged to the feeding roller 10 by the intermediate plate 9 and the feeding roller comes into contact with the paper, the feeding roller starts to rotate and conveys the paper to the nip between the separation pad 1 and the feeding roller 10. When the paper pressurized by the intermediate plate 9 is fed by the feeding roller 10, a plurality of sheets, for example, two sheets may be conveyed, but these two sheets are conveyed to the registration rollers as they are. If this happens, double feeding will occur and a paper jam will occur inside the machine. In order to prevent this, the paper close to the separation pad, that is, the paper on the lower side among the papers conveyed by the two separation pads is blocked, that is, the paper is separated so that only the uppermost paper is conveyed.
[0007]
The separation pad is generally composed of a plate-like friction member 1a in which cork is contained in urethane rubber, and a support member 1b that supports the friction member. The separation pad is pressurized from below by a compression coil spring 1c or the like. ing. This pressurizing force is set so as not to cause a feeding failure, that is, a state where the paper cannot be moved, or a state where a double feed, that is, a plurality of sheets of paper are conveyed at a time. Specifically, double feeding occurs when the pressure is too low, and poor feeding occurs when the pressure is too high.
[0008]
[Problems to be solved by the invention]
When feeding paper from such a multi-hand feeding device, the fed paper enters the nip of the registration roller and then makes a loop in front of the registration roller to make the paper multi-feed. The skew correction is performed in the case of skew, and the registration roller starts rotating in synchronization with the optical system, thereby aligning the paper and the image on the photosensitive drum in the paper transport direction. However, at this time, when the paper to be transported is a thick paper such as a postcard, a force is applied to make the rear end of the paper return in the direction opposite to the paper transport direction by forming a loop.
[0009]
As shown in FIG. 8, the trailing edge of the paper is sandwiched between the feeding roller 10 and the separation pad 1, and the force of pressing the paper of the separation pad is the force of the waist of the paper forming the loop, that is, the separation pad in the direction of arrow C. Losing the force to push the sheet into the sheet may reduce the force to pinch the paper at the separation pad portion, and may cause a phenomenon in which the trailing edge of the paper moves in the direction opposite to the paper transport direction.
[0010]
When this phenomenon occurs, the number of loops once formed is reduced, an appropriate amount of loops cannot be formed, and skew correction is not performed sufficiently. There is a possibility that a phenomenon that the position of the tip is displaced occurs. In order to prevent such inconvenience, it is possible to securely hold the loop at the rear end side by providing a pair of conveying rollers between the feeding roller portion and the registration roller, but this increases the manufacturing cost and is limited. It is expected that adding a pair of rollers in the space will cause problems such as a decrease in the area where the loop is formed and the skew correction not being performed sufficiently.
[0011]
[Means for Solving the Problems]
Therefore, in order to solve the above-described problem, the first invention provides a feeding unit that feeds a sheet, a separating unit that is disposed opposite to the feeding unit and that separates the sheet, and a sheet conveying direction from the feeding unit. and a conveying means for conveying the located downstream sheet, the sheet feeding apparatus makes forming a loop in the sheet abutted against the conveying means of the sheet front end for feeding by the feeding means, feeding of the sheet by the feeding means The pressure applied to the sheet by the separating means and the feeding means can be changed during feeding, and the above-described state in which the loop is formed by striking the sheet against the conveying means rather than the above-described pressure in the state where the sheets are separated one by one characterized Rukoto increase pressure.
[0013]
According to a second aspect of the present invention , there is provided a moving means for supporting the separating means so as to be swingable, moving the separating means close to and away from the feeding means , and feeding the separating means by the moving means during feeding of the sheet by the feeding means. by Rukoto it swung close to the feeding means side, characterized in that to increase the pressure against the sheet by the separating means and the feed means.
[0014]
In the third invention , the moving means of the separating means includes a rotatable cam member, a reciprocating member guided by the guide member , a link for transmitting the movement of the cam member to the reciprocating member, and the movement of the reciprocating member. It has a spring which transmits to a separating member.
[0015]
According to a fourth aspect of the present invention , the feeding means is composed of a feeding roller having a small diameter portion corresponding to the sheet separation stroke and a large diameter portion corresponding to the feeding stroke after the separation stroke is completed , and the separation means is the feeding roller. It is characterized by comprising a separation pad biased by a spring on the roller side.
[0016]
According to a fifth aspect of the present invention , the feeding means is constituted by a feeding roller for feeding sheets , the separating means is constituted by a separation pad pressed by a spring against the feeding roller, and a plurality of sheets are stacked and driven by a driving means. provided sheet stacking means to close-spaced to the feeding roller, when the sheet stacking means is moved away against the feeding roller in the sheet feeding of by the feed roller in close proximity to the roller feeding the sheet stacking means And an interlocking means for moving the separation pad with respect to the feeding roller in a direction in which the pressure is increased .
[0017]
A sixth invention is the sheet stacking means has a middle plate for stacking sheets, interlocking means possess a protruding portion engaged with the cam member provided on the cam member and the separation pad provided in the intermediate plate , the cam member when the intermediate plate is separated from the feed roller, characterized in Rukoto increased pressure against the feed roller of the separation pad by pressing the protrusion.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
[Embodiment 1]
Hereinafter, an embodiment of a feeding device according to the present invention will be described.
[0021]
As shown in FIG. 1, the compression coil spring 2 presses the separation pad 1, and one end of the spring 2 is engaged with the separation pad 1. A piston member 3 as a reciprocating member is guided by a cylindrical cylinder 4 as a guide member, and the other end of the spring 2 is installed in a recess 3 a provided in the piston member 3. One end of a link 5 is connected to the piston member 3, and the other end of the link 5 is connected to a cam plate 7 that rotates about a shaft 6. The shaft 6 is connected to driving means such as a stepping motor (not shown), and this motor is controlled by a controller (not shown).
[0022]
Paper as a sheet on the tray 8 is pressed against the feeding roller 10 by the middle plate 9 being lifted upward by a biasing means such as a spring (not shown), and immediately after that, the feeding roller 10 starts to rotate, The paper is separated and fed one by one by the feed roller 10 and the separation pad 1. When the leading edge of the paper reaches the pre-registration detection sensor 11 and the sensor detects the leading edge of the paper, the detection signal is transmitted to the controller. Upon receiving this signal, the controller senses that the paper is just before making a loop, and issues a signal to a cam plate drive motor (not shown) to rotate a predetermined amount.
[0023]
As shown in FIG. 2, the cam plate 7 starts to rotate in the direction of arrow A by the rotation of the shaft 6 by the motor, and moves the piston member 3 upward. As a result, the compression coil spring increases the pressure applied to the separation pad 1 from below, and the pressure applied to the separation pad 1 is maximized before a complete paper loop is formed as shown in FIG. Thus, by increasing the applied pressure of the separation pad 1 during the loop formation process without changing during the separation process, the separation pad loses the stiffness of the cardboard as in the conventional case, ie, in the direction opposite to the pressurizing direction, that is, downward. It is possible to prevent the rear portion of the paper from moving backward and retreating in the direction opposite to the conveying direction and incomplete loop formation. The pressurizing force at this time is larger than the pressurizing force at the time of separating the normal paper, and the pressurizing force is too high to cause a feeding failure, but the separation process has already been completed as shown in FIG. Then there is no problem.
[0024]
When the registration roller 12 starts to rotate at a timing with an optical scanning system (not shown), the separation pad pressure does not have to be maintained at a high level as shown in FIG. , Must return to the original pressure. Therefore, the cam plate 7 continues to rotate and returns to the position shown in FIG.
[0025]
[Embodiment 2]
In the embodiment, after detecting the paper leading edge position, the separation pad pressure is increased immediately before the loop is formed, that is, immediately before the separation pad pressure starts to decrease due to the strength of the paper. . On the other hand, in the present embodiment, taking into consideration the transport amount from the paper separation pad to the registration roller in advance, the rotation radius of the large-diameter portion formed on the feeding roller 10 is maximized immediately before loop formation, and the separation pad is formed. The pressure is to be increased.
[0026]
FIG. 4 is a cross-sectional view showing another embodiment of the present invention, and the feed roller 10 has a large-diameter portion 10a as shown.
[0027]
FIG. 4 shows a state in which the feeding roller 10 has already started rotating from the standby state and is feeding paper. The feed roller is further rotated from this state to be in the state shown in FIG. Since the feeding roller 10 pushes down the separation pad 1 downward (in the direction of arrow B) in the region of the large diameter, the compression coil spring 2 supported by the fixed spring cradle 2a is compressed and applied pressure to the separation pad 1 Even if a loop as shown in the figure occurs, the trailing edge of the paper does not move backward upstream.
[0028]
In the feeding device of this embodiment, the feeding roller 10 must always return to the standby state at the start of feeding. In FIG. 4, the feed roller stands by in a state where the standby point 10a on the feed roller 10 corresponds to the friction member point 1a of the separation pad. Starting from this state, in order to separate the paper one by one without causing poor feeding by the feeding roller and the separation pad, the feeding roller 10 has a predetermined range in the direction opposite to the rotation direction from the standby point 10a. The normal reference radius is a circle. As shown in FIG. 4, after the intermediate plate 9 is lowered and the separation process is finished, before the paper loop is formed, the diameter of the large portion is increased within a predetermined range from the start point 10c so that the separation pad pressure can be increased. 10a is formed.
[0029]
In this embodiment, the paper loop formation after the leading edge of the paper reaches the registration roller can be completed with a simple configuration having a smaller number of parts than in the previous embodiment.
[0030]
[Embodiment 3]
As described above, when the separation pad pressure is not an appropriate pressure when one sheet is to be separated from a plurality of sheets, poor feeding or double feeding occurs. The reason why the pressure should be appropriate is that the intermediate plate presses the paper against the feeding roller based on the operation sequence of the feeding device. Hereinafter, the operation order of the middle plate 9 and the feeding roller 10 will be described with reference to the drawings.
[0031]
The intermediate plate is supported so as to be able to swing around the rotation shaft, and is pressed from below by a compression coil spring (not shown) like the separation pad. In this state, swinging is started to press the paper placed on the surface of the intermediate plate toward the feeding roller by the intermediate plate driving means (not shown). When the pressurization is completed, the feeding roller starts to rotate. At this time, if the pressing force of the intermediate plate is not sufficiently increased, the feeding roller and the paper slip. When the feed roller rotates, the leading edge of the paper enters the nip between the feed roller and the separation pad, and the separation pad presses the paper against the feed roller, thereby generating a transport force of the feed roller against the paper. By this action, the paper can be conveyed to the registration rollers only with this force. Therefore, in accordance with this timing, it is meaningless for the intermediate plate to press the paper against the feeding roller, and the intermediate plate is lowered by the driving means. If the plate does not descend during this period, double feed occurs due to the transport force generated by the plate to press the paper against the feed roller. This is because the separation pad works to dampen excess paper when multiple sheets of paper enter the nip, but this transport force strikes the force to dampen excess paper, which causes separation failure. It becomes double feeding.
[0032]
It can be said from the above operation sequence that when the intermediate plate is raised to press the paper against the feeding roller, the separation pad is in the paper separation process. However, an appropriate amount must be maintained, but the separation pad pressure has a degree of freedom at other times, that is, when the intermediate plate is lowered.
[0033]
In this embodiment, the above-described reasoning is applied, and the separation pad pressure is changed in conjunction with the operation of the intermediate plate.
[0034]
FIG. 6 is a cross-sectional view showing this embodiment. The middle plate 9 shown in this figure has a rotation center 9a, and is supported so as to be swingable by a driving device (not shown) around this center. The state in which the middle plate 9 is shown by a solid line is a state in which the feeding roller is pressed. At this time, the cam 27 that rotates integrally with the middle plate coaxially with the center of rotation of the middle plate is also in the position of the solid line. When the paper on the intermediate plate enters the nip of the separation pad and the intermediate plate finishes its role, the intermediate plate rotates together with the cam to the dotted line position (in the direction of arrow D). At this time, the separation pad 1 comes into contact with an elastic protrusion 28 integrally formed with a separation pad made of resin, and the protrusion 27 is pressed and deformed by the cam 27 as shown in the figure, whereby the separation pad 1 is rotated by the rotating shaft 1f. Rotating around and urged to the feeding roller side, the feeding roller pressure rises from the appropriate value for separation, and even if a loop is formed, the paper can be securely held, and the decrease in the loop amount can be stopped. It is.
[0035]
【The invention's effect】
As described above, according to the present invention, the sheet is separated and fed one by one by the feeding means for feeding the sheet and the separating means arranged to face the feeding means, and the sheet is fed from the feeding means. In a sheet feeding device that forms a loop on the sheet by abutting the leading edge of the sheet against the conveying means located downstream in the feeding direction, the pressure applied to the sheet by the separating means and the feeding means can be varied during sheet feeding by the feeding means Therefore, the separating means and the feeding means can be securely held without losing the trailing edge of the sheet on which the loop is formed, thereby increasing the pressing force of the separating means during loop formation. Correction defects and image position defects can be prevented in advance.
[Brief description of the drawings]
FIG. 1 is a diagram showing a state in which a separation pad pressure is minimal in an embodiment of a feeding apparatus according to the present invention. FIG. 2 is a state in which a separation pad pressure is intermediate in an embodiment of a feeding apparatus according to the present invention. FIG. 3 is a diagram showing a state in which the separation pad pressure of the embodiment of the feeding device according to the present invention is maximum. FIG. 4 is a diagram showing the state during feeding of the second embodiment of the feeding device according to the present invention. FIG. 5 is a diagram showing a state in which the separation pad pressure is maximum in the second embodiment of the feeding device according to the present invention. FIG. 6 is a diagram showing a third embodiment of the feeding device according to the present invention. FIG. 7 is a cross-sectional view of an electronic copying machine targeted by the present invention.
FIG. 8 is a cross-sectional view illustrating a problem that has occurred in a conventional multi-manual feeding apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Separation pad 1a ... Friction member 2 ... Spring 2a ... Spring cradle 3 ... Piston member 4 ... Cylinder 5 ... Link 6 ... Shaft 7 ... Cam plate 8 ... Tray 9, 14 ... Middle plate 10, 16 ... Feed roller 10a ... large diameter part 10b ... standby point 10c ... start point 11 ... sensor 12 ... registration roller 13 ... cassette 15 ... sheet 21 ... photosensitive drum 22 ... developing device 25 ... fixing device 27 ... cam 28 ... projection

Claims (6)

Yes and the feeding means for feeding sheets, and separating means for separating the sheets is arranged facing to said feeding means and conveying means for conveying the positioned sheet conveying direction downstream side of said feeding means sheet and, in the sheet feeding apparatus which makes a loop in the sheet leading edge of the sheet abutted against the transport means for feeding by said feeding means,
It said feeding means pressure variation can configured with respect to the seat by the feeding means and the separating means in the feeding of the sheet by,
Sheet feeding apparatus according to claim Rukoto increasing the pressure in a state to form a loop abutted against the sheet to the conveying means than the pressure in a state of separating the sheets one by one. Said separating means swingably supporting said separating means is provided moving means for close-spaced with respect to said feeding means, said said separating means by said moving means in the sheet feeding of by the feeding means by Rukoto it swung close to the feeding means side, the separating means and the sheet feeding apparatus according to claim 1, wherein the increasing the pressure on the sheet by the feeding means. Wherein said moving means of the separating means includes a rotatable cam member, a reciprocating member that is guided by the guide member, and a link for transmitting the movement of said cam member to said reciprocating member, the movement of said reciprocating member The sheet feeding apparatus according to claim 2, further comprising a spring that transmits the separation member. The feeding means is composed of a feeding roller having a small diameter portion corresponding to the separation process of the sheet and a large diameter portion corresponding to the feeding process after the separation process, and the separating means is disposed on the side of the feeding roller. 2. The sheet feeding apparatus according to claim 1 , wherein the sheet feeding apparatus is constituted by a separation pad biased by a spring. Said feeding means is constituted by a feeding roller for feeding the sheet, the separating means is constituted by a separation pad that is pressed by the spring against the feed roller, feeding the paper by stacking and drive means a plurality of sheets provided sheet stacking means to close-spaced relative roller, spaced said in sheet feeding of by the feed roller the sheet stacking means in proximity to the feed roller sheet stacking means against said feeding roller when moving, the separation pad sheet feeding according to claim 1, characterized in that it comprises an interlocking means for moving in a direction in which the pressing force to the feeding roller is increased device. Said sheet stacking means includes a middle plate for stacking sheets, said interlocking means, possess a protruding portion engaged with the cam member provided in the separation pad and the cam member provided on the intermediate plate, the sheet of claim 5, wherein the intermediate plate is characterized Rukoto increase the pressure against the feed roller of the separation pad the cam member presses the protruding portion when separated from the feed roller Feeding device.

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