JP2010269923A - Paper feeder and image forming apparatus including the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a paper feeder applicable to high-speed machines which prevents multiple feeding and non feeding even when temperature and humidity environment is changed; and an image forming apparatus including the paper feeder. <P>SOLUTION: The paper feeder includes a paper mounting table mounting stacked papers and moving vertically; a paper position detection means for detecting the uppermost paper position; a paper feeding position changing means for maintaining the paper position at a predetermined paper feeding position; a delivery means for delivering the uppermost paper; a paper feeding roller for receiving the paper; a separating roller for preventing the multiple feeding which is pressed into contact with the paper feeding roller; a tilted surface holding member disposed between the paper feeding roller and the delivery means, and including a tilted surface which the distal end of the delivered paper abuts against and climbs over; and a temperature detection means and a humidity detection means for detecting ambient temperature and humidity, respectively. When the temperature and the humidity detected by the temperature detection means and the humidity detection means are lower than the values of low temperature/low humidity reference values, the uppermost paper position is changed to a position higher than the predetermined paper feeding position. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a sheet feeding device and an image forming apparatus such as a copying machine and a printer including the sheet feeding device.

  In an image forming apparatus such as a copying machine, a facsimile machine, or a printer, a sheet is supplied one by one from a sheet feeding device such as a sheet feeding tray, and a toner image formed by an electrophotographic method in an image forming unit is transferred onto a sheet in a transfer unit. The visible image is fixed and formed.

  In such an image forming apparatus, separation between sheets may be difficult due to changes in the indoor environment such as temperature and humidity, friction coefficient of the sheet surface, electrostatic adsorption force between sheets, and the like. A phenomenon of so-called double feeding occurs in which the sheets are transported in an overlapped state or in a state of being overlapped with a staircase shape. On the other hand, apart from this double feed, there is also a problem of no feed in which the paper cannot be sent out.

In addition, the amount, size, and material of paper used are diversified, and the amount of paper is from about 50 g / m ^{2 to} about 350 g / m ² , from postcard size to 13 × 18 inches. Up to the size is generally used. Furthermore, various types of paper such as plain paper, recycled paper, coated paper, and specially processed paper are required to be fed, and double feed and no feed are likely to occur.

  Conventionally, as a method for preventing double feeding, a method using a rolling roller, a method of getting over an inclined surface holding member, a method of adjusting a contact pressure between a feeding roller and a sheet, and the like are known.

  Patent Document 1 (Japanese Patent Application Laid-Open No. 6-107349) discloses a paper feeding device that uses a roller. This paper feed device includes a feed roller that is pressed against the paper, a paper feed roller for preventing double feed, and a winding roller. When paper is fed, first, the upper surface position of the paper is raised to the set position, and the feed roller and the paper feed roller start rotating simultaneously by a paper feed signal. The feed roller that is pressed against the upper surface of the paper at a predetermined position feeds the paper to the nip position between the paper feed roller and the separating roller. A torque limiter is connected to the winding roller and is in pressure contact with the paper feed roller. The torque limiter connected to the separation roller exceeds the limit torque when the feed roller and the separation roller are in direct contact (when there is no paper between the nips) or when a sheet of paper is fed between the nips. The sliding and rolling roller rotates following the paper feed roller. However, when two or more sheets are fed between the nips, the limit torque overcomes the frictional force between the sheets, rotates the roller in the reverse direction, pushes the lower sheet back, and multi-feeds (multi-sheet feeding). Is preventing. As described above, the sheets that are separated and fed one by one are conveyed to the registration rollers to form an image.

  Further, the method of overcoming the inclined surface of the inclined surface holding member is to abut the leading edge of the paper fed by the delivery roller against the inclined surface of the inclined surface holding member, so that the overlapping sheets are one by one on this inclined surface. It is intended to be separated. In some cases, a resistance member is added to the inclined surface in order to improve paper feeding performance.

  Patent Document 2 (Japanese Patent Application Laid-Open No. 2007-55705) uses this inclined surface, and in particular, a movable configuration that can change the angle of the inclined surface and the angle in the height direction are changed. It has a fixed configuration. The fixed configuration also includes a paper feed position changing unit that can change the uppermost position of the sheet bundle.

  Patent Document 3 (Japanese Patent Application Laid-Open No. 2004-277114) also uses this inclined surface, but is an example in which double feeding can be prevented even when the loaded paper has curls. That is, the degree of curling of the stacked paper is detected by a sensor, and the inclination angle of the inclined surface can be changed according to the degree of curling.

  Although these techniques are effective for double feeding and no feed, there is a problem that the optimum conditions change depending on the temperature and humidity conditions.

  In order to solve this problem, Japanese Patent Application Laid-Open No. 2003-112838 discloses a technique of changing the angle of the inclined surface of the inclined surface holding member according to the temperature and humidity conditions. Patent Document 4 discloses that the angle of the inclined surface is changed depending on the thickness and elasticity of the paper.

  However, in order to change the angle of the inclined surface of the inclined surface holding member, it is necessary to have a configuration that makes this inclined surface movable, and a power source for inclining the inclined surface is necessary, which is a factor in increasing costs. Become.

JP-A-6-107349 JP 2007-55705 A JP 2004-277114 A JP 2003-112838 A

  SUMMARY OF THE INVENTION An object of the present invention is to provide a sheet feeding device that has a simple configuration but does not cause double feeding or no feed even when temperature and humidity conditions change, and an image forming apparatus including the sheet feeding device.

  The object is achieved by the following invention.

1. A stack of sheets mounted as a bundle of sheets, a sheet mounting table that moves up and down, and
A paper feed position detecting means for detecting the uppermost paper in the paper bundle;
A paper feed position changing means for moving the paper mounting table so that the uppermost paper position of the paper bundle maintains a predetermined paper feed position based on the detection of the paper feed position detecting means;
Delivery means for delivering the uppermost sheet of the sheet bundle;
A paper feed roller for receiving the fed paper,
A double-rolling prevention roller that is in pressure contact with the paper feed roller;
An inclined surface holding member provided with an inclined surface between the paper feeding roller and the feeding means and overcoming the leading edge of the paper fed from the feeding means;
Temperature detection means and humidity detection means for detecting ambient temperature and humidity; and when the temperature and humidity detected by the temperature detection means and humidity detection means are lower than a preset low-temperature and low-humidity reference value, A paper feeding device that changes the uppermost paper position of the paper bundle to a position higher than the predetermined paper feeding position.

  2. When the humidity detected by the humidity detector is higher than a preset high humidity reference value, the uppermost sheet position of the sheet bundle is changed to a position lower than the predetermined sheet feeding position. The sheet feeding device according to 1.

  3. The paper feeding position determining means for storing a paper feeding position adapted to the type of paper, and changing the top paper position of the paper bundle according to the type of paper used The sheet feeding device according to 2.

  4). A paper feed error handling means for counting the frequency of occurrence of paper feed errors, and when the frequency of paper feed errors counted by the paper feed error handling means exceeds a preset paper feed error frequency reference value, 4. The sheet feeding device according to any one of 1 to 3, wherein the uppermost sheet position of the sheet bundle is changed.

5). A paper feed time corresponding means for measuring a paper feed time from when the feed means starts feeding the top sheet of the paper bundle to a transport roller located downstream in the paper transport direction of the feed means; Have
The sheet feeding device according to any one of claims 1 to 4, wherein the uppermost sheet position of the sheet bundle is changed according to the sheet feeding time.

  6). The curling unit that detects the direction and size of the curl of the sheet is provided, and the uppermost sheet position of the sheet bundle is changed according to the detection result of the curl unit. The sheet feeding device according to any one of the above.

  7). The inclined surfaces of the inclined surface holding member are formed such that an angle between the inclined surface and a sheet abutting on the inclined surface is reduced along a sheet traveling direction. The sheet feeding device according to any one of the above.

  8). The sheet feeding device according to any one of 1 to 7, wherein an inclination angle formed by the inclined surface holding member and the sheet is more than 0 ° and less than 90 °.

  9. An image forming apparatus comprising the paper feeding device according to any one of 1 to 8 above.

  According to the present invention, without using a special mechanism or a new power source, even if the ambient temperature or humidity changes, a paper feeding device that can suppress the occurrence of double feed or no feed, or an image including the same. A forming apparatus can be provided.

1 is a schematic cross-sectional view showing an embodiment of an image forming apparatus according to the present invention. It is sectional drawing of LCT which is a large capacity | capacitance paper feeder. FIG. 5 is an enlarged plan view of feeding units 50A and 50B in the first and second embodiments of the paper feeding device according to the present invention. FIG. 3 is an enlarged cross-sectional view of an enlarged peripheral portion of a feeding unit 50A in the first embodiment of the paper feeding device of FIG. FIG. 3 is a block diagram of a control system according to a general operation of the paper feeding device of the present invention. It is an expanded sectional view which shows the structure of the delivery unit 50B in 2nd Embodiment of the paper feeder of this invention. FIG. 5 is a block diagram of a control system related to an operation when changing a paper feed position by means including special means in the paper feed device of the present invention. 6 is a flowchart for explaining a procedure for changing a paper feed position in the paper feeder of the present invention.

  Hereinafter, although the structure and operation | movement of embodiment of this invention are demonstrated, this invention is not limited to this embodiment.

  FIG. 1 is a schematic sectional view showing an embodiment of an image forming apparatus according to the present invention. The image forming apparatus shown in FIG. 1 includes an image forming apparatus main body 10 that forms an image on a sheet by an electrophotographic method, an automatic document conveying device 20 that conveys a document to a reading position, a first post-processing device 30, and a first post-processing device 30. 2 post-processing device 40. The second post-processing device 40 is a device that performs post-processing such as binding processing on a sheet on which an image is formed by the image forming apparatus main body 10 and conveyed from the first post-processing device 30. The automatic document feeder 20 includes a document feeder 21 on which a document is placed, a platen roller 22 that transports the document to a reading position, and a document discharge table 23 on which the scanned document is placed.

  The image forming apparatus main body 10 includes a photoconductor 11, an image forming unit 12, storage units 13a, 13b, and 13c, paper feeding units 18a, 18b, and 18c, a reverse paper feeding unit 14, and a fixing device 15. Have. The image forming unit 12 charges, exposes, and develops the photoconductor 11 to form a toner image, and transfers the toner image formed on the photoconductor 11 to a sheet. The storage units 13a, 13b, and 13c store various sizes of paper by distinguishing them according to size. The paper feeding units 18 a, 18 b, and 18 c include a group of rollers that carry out the sheets one by one from the storage units 13 a, 13 b, and 13 c and convey them to the image forming unit 12. The reversing paper feeding unit 14 reverses the paper recorded on one side when forming images on both sides of the paper, and conveys the paper to the image forming unit 12. The fixing device 15 fixes the toner image transferred on the paper. The image forming apparatus further includes an LCT 50 that is a large-capacity paper feeding device, and feeds an image from the LCT 50 to the image forming unit 12 to form an image.

  The control means 95 is built in the image forming apparatus main body 10 and controls the operation of each part of the image forming apparatus, and between the automatic document feeder 20, the first post-processing apparatus 30, the second post-processing apparatus 40, and the LCT 50. It controls the operation of these devices by exchanging signals.

  FIG. 2 is a cross-sectional view of an LCT 50 that is a large capacity sheet feeding device. The paper P is placed on a paper feed table 52 as a paper placement table that can be raised and lowered. When the sheet P positioned at the top of the sheet stack placed on the sheet feed tray 52 rises to a predetermined sheet feeding position, a feeding roller 53 as a feeding means contacts the upper surface of the sheet P positioned at the top, and the sheet Send P in order from the highest. In other words, the height of the sheet P positioned at the top of the sheet bundle is the predetermined sheet feeding position. The sheet P is separated into one sheet by the sheet feeding roller 54 and the separating roller 55 whose rotation is regulated by the torque limiter and pressed against the sheet feeding roller 54, and the separated sheet P is conveyed to the conveying roller 56 to form an image. It is conveyed to the section 12 (see FIG. 1). The feeding roller 53, the paper feeding roller 54, the separating roller 55, and the peripheral members thereof constitute a feeding unit 50A in the first embodiment of the paper feeding device, which will be described later, or a feeding unit 50B in the second embodiment.

  The sheet feed table 52 is driven by two motors 60 and 70 as sheet feed position changing means provided at the bottom of the frame 51 of the LCT 50 to move the sheet feed table 52 in the vertical direction (the direction of arrow b) in the figure. Go up and down. A motor 70 as a forward lifting motor raises and lowers the paper feed tray 52 in the front portion in the paper feeding direction a, and a motor 60 as a rear lifting motor lifts the paper feed tray 52 in the rear portion in the paper feeding direction a. The lifting mechanism at the rear end of the sheet feeding direction 52 of the sheet feeding table 52 is a motor 60, wire pulleys 62 and 63 fixed to both ends of a rotating shaft 61 of the motor 60, a wire 66 having one end attached to the wire pulleys 62 and 63, 67 and pulleys 64 and 65 attached to the frame 51. The wires 66 and 67 support both rear end portions of the paper feed table 52 in a direction perpendicular to the paper feed direction a and perpendicular to the paper surface. The lifting mechanism of the front end of the sheet feeding base 52 in the sheet feeding direction “a” includes a motor 70, wire pulleys 72 and 73 fixed to a rotating shaft 71 of the motor 70, wires 76 and 77 having one ends attached to these wire pulleys 72 and 73, and The pulleys 74 and 75 are attached to the frame 51. The wires 76 and 77 support both front end portions in a direction perpendicular to the paper feed direction a of the paper feed tray 52 and perpendicular to the paper surface.

  The motors 60 and 70 operate based on the outputs of sensors Su, Ss, and Sd as a paper feed position detection unit (described later) that detects the uppermost paper position of the paper bundle as the paper feed position. Thus, the paper feed base 52 is raised in the direction b to keep the paper feed position at a constant level. Accordingly, stable paper feeding is performed regardless of fluctuations in the amount of paper P on the paper feed tray 52.

  In the frame 51, guide plates 80 and 81 for guiding the paper P at both ends of the paper width are provided so as to be movable according to the paper width. Further, the frame 51 is provided with a guide plate 82 as a rear end guide member for guiding the paper P at the rear end of the paper feeding direction a so as to be movable in the paper feeding direction a, and is set at a position corresponding to the paper size. Is done.

  As shown in FIG. 2, encoders 68 and 78 are fixed to the rotation shafts 61 and 71 of the motors 60 and 70, respectively, and the rotation amounts of the encoders 68 and 78 are detected by sensors 69 and 79, respectively.

  FIG. 3 is an enlarged plan view of the feeding units 50A and 50B in the first and second embodiments of the paper feeding device according to the present invention. FIG. 4 is an enlarged cross-sectional view in which a peripheral portion of the feeding unit 50A in the first embodiment of the paper feeding device of FIG. 2 is enlarged.

  The feeding units 50A and 50B include a feeding roller 53, a paper feeding roller 54, a shaft 54a of the paper feeding roller 54, a belt 57, sensors Su, Ss, Sd, connecting rods 91, 93, sensors Sd, Ss, Su, and an inclined surface. It consists of holding members 100, 200, 210 and the like. The difference between the first embodiment and the second embodiment in the sheet feeding device of the present invention is the difference in shape between the inclined surface holding member 100 and the inclined surface holding members 200 and 210.

  First, the delivery unit 50A of the first embodiment will be described with reference to FIGS.

  3 and 4, the feeding roller 53 is a grooved roller so that the uppermost sheet P of the sheet bundle can be reliably fed out. The feed roller 54 and the feed roller 53 are coupled by connecting rods 91 and 93, the shaft 54 a of the feed roller 54 serves as a drive shaft, and the rotation of the feed roller 54 is transmitted to the feed roller 53 by the belt 57. Further, the feed roller 53 is rotatably held around the shaft 54a of the paper feed roller 54, and the feed roller 53 can be kept in pressure contact with the upper surface of the paper by its own weight. Accordingly, the paper P is normally delivered even if the height (paper feed position) at which the paper P is fed changes in the vertical direction.

  The actuator 90 that detects the sheet height of the uppermost sheet P of the sheet bundle includes a support shaft 90a that is rotatably attached to the shaft 54a, and a detection unit 90b that includes an annular portion that loosely fits the shaft of the feed roller 53. And a light shielding portion 90c that shields the sensors Su, Ss, and Sd. Since the detection unit 90b is heavier than the light shielding unit 90c, the detection unit 90b is lowered, and the lower end of the detection unit 90b comes into contact with the uppermost sheet P of the sheet bundle, so that the upper end position of the sheet bundle is identified. The sensors Su, Ss, and Sd that are provided on the frame of the paper feeding device are each provided with a projector and a light receiver, and the light shielding portion 90c of the actuator 90 enters between the light projector and the light receiver. The height of the uppermost sheet P is detected by shielding the sensors Su, Ss, and Sd. A sensor Ss located between the sensors Su and Sd detects that the paper feed table 52 is stopped with the position of the paper feed position Ps as a predetermined paper feed position when conditions such as temperature and humidity are in a normal state. A sensor Sd located below the sensor Ss detects a position Pd lower than a predetermined paper feed position, and a sensor Su located above the sensor Ss detects a position Pu higher than the predetermined paper feed position to feed paper. The platform 52 is stopped. Which of the three sensors Sd, Ss, and Su as the paper feed position detection means is detected by the light shielding portion 90c is determined by an instruction from the control means 95. The control means 95 selects one of the sensors based on various conditions (described later) such as environmental conditions such as temperature and humidity, the type of paper, the frequency of occurrence of paper feed errors, the length of paper feed time, and the degree of paper curl. select. That is, when there is a condition in which double feeding of paper is likely to occur, the paper feeding position is set to a position Pd lower than the predetermined paper feeding position, thereby increasing the resistance of paper conveyance and preventing the conveyance of the following paper. Can do. Further, when there is a condition in which no feed is likely to occur, by setting the paper feed position to a position Pu higher than the predetermined paper feed position, it is possible to reduce the paper transport resistance and smooth the paper transport.

  When any one of the three sensors Sd, Ss, and Su is selected, the corresponding paper feed positions Pu, Ps, and Pd (see FIG. 4) are determined, and the uppermost sheet P of the sheet bundle is Then, the paper is fed from one of the determined paper feed positions.

  In the first embodiment of the present invention, as shown in FIGS. 3 and 4, the inclined surface holding member 100 having an inclined surface 100 a having a uniform inclination angle θ between the feed roller 53 and the paper feed roller 54. Is provided. The paper P sent out from any one of the three paper feed positions Pu, Ps, and Pd is set so as to abut against the inclined surface 100a, get over the inclined surface 100a, and be sent out toward the image forming unit 12.

  The inventor can obtain good results through experiments by setting the inclination angle θ of the inclined surface 100a of the inclined surface holding member 100 in the first embodiment to a range of more than 0 ° and less than 90 °. I have confirmed that.

  According to the present embodiment, the inclined surface 100a of the inclined surface holding member 100 is fixed, and the resistance of paper conveyance is controlled by the position where the paper P abuts on the inclined surface 100a. There is no need to make an expression. Therefore, the configuration can be simplified, and the motor as a power source is originally intended to raise and lower the paper feed table 52 and does not need to be provided specially, so that the manufacturing cost can be kept low.

  FIG. 5 is a block diagram of a control system related to a general operation of the sheet feeding device of the present invention. When conditions such as environmental conditions such as temperature and humidity are in the normal state, the motors 60 and 70 as the paper feed position changing means are controlled by the control means 95 through the sensors 69 and 79 and the sensor Ss as follows. The When the sensor Ss detects that the paper feed position of the paper P has fallen below the predetermined paper feed position Ps, the controller 95 operates the motors 60 and 70 based on the detected signal to raise the paper feed tray 52. The position of the paper P is raised. When the position of the paper P reaches a predetermined paper feed position Ps by the operation of the motors 60 and 70, the motors 60 and 70 are stopped based on the detection signal from the sensor Ss.

  The control means 95 also controls the rotation amount of the motor 70 so as to always be equal to the rotation amount of the motor 60 based on the rotation detection signals of the sensors 69 and 79. As a result, the paper feed tray 52 always moves up and down in the direction of arrow b in FIG.

In the block diagram of the control system of the paper feeder shown in FIG. 5, the control means 95 has an input unit 96 for inputting paper data. From here, the type of paper P accommodated in the LCT 50 serving as the paper feeder is shown. Data can be input. The input unit 96 can use the input unit of the image forming apparatus main body 10. Examples of input data include, for example, a plain paper of A4 size with a 斤 g / m ² , or a B5 size coated paper with a 斤 amount of ΔΔg / m ² . The input data is stored in the memory 95a of the control means 95.

  Further, the control means 95 includes a paper feed position determining means 97 that is a program that stores an optimum paper feed position corresponding to the type of paper as a table, which is set in advance by experiments. When the data of the paper P is input from the input unit 96, the control unit 95 searches for which paper type of the data in the paper feed position determining unit 97 matches this data, and determines a predetermined optimum for the paper type. Select the paper feed position. Based on the information on the predetermined paper feed position, the control means 95 instructs the paper feed position adjusting means 101 to adjust the paper feed position.

  The paper feeding device of the present invention is not limited to the LCT 50, and may include the storage units 13a, 13b, and 13c and the corresponding paper feeding units 18a, 18b, and 18c. Constitutes three sheet feeding devices different from the LCT 50. Each sheet feeder stores sheets P of different sizes and quality, and data of these sheets P can be input in advance from the input unit to the memory 95a. Therefore, when the operator selects one of the paper feeding devices, the control means 95 determines the paper feeding position suitable for the paper P stored in the paper feeding device via the paper feeding position determining means 97. The paper feed position designated by the paper feed position adjusting means 101 is set.

  The paper feed position adjusting unit 101 according to the present embodiment includes a control board, selects a circuit connected to any one of the three sensors Su, Ss, and Sd based on an instruction from the control unit 95, and the remaining circuits. The sensor to be used is selected by blocking.

  When the control unit 95 selects one sensor by the paper feed position adjusting unit 101, if the paper to be used is a thick paper or a highly rigid paper, it is difficult to get over the inclined surface 100a, so that the paper feed position is above the inclined surface 100a. The sensor Su is selected so as to select the paper feed position Pu located at the position. In the case of thin paper or low-rigidity paper, the sensor Sd is selected to select the paper feed position Pd where the paper feed position is located below the inclined surface 100a to prevent the occurrence of double feeding. That is, when the sensor Su is selected by the paper feed position adjusting means 101, the paper feed stand 52 is raised until the light shielding portion 90c of the actuator 90 is detected by the sensor Su, and the uppermost paper P in the paper bundle is The position reaches the paper feed position Pu. Similarly, when the sensor Sd is selected, the uppermost sheet P reaches the position of the paper feed position Pd, and when the sensor Ss is selected, the uppermost sheet P is at the position of the predetermined paper feed position Ps. Reach. Thus, when the paper feed position adjusting unit 101 selects one of the three sensors Su, Ss, and Sd, the uppermost paper P in the paper bundle is positioned at any one of the paper feed positions Pu, Ps, and Pd. Set to be sent from

  The above configuration is the same as that of a conventional paper feeding device. The characteristic configuration of the present invention will be described below.

  A temperature detection sensor 98 as temperature detection means and a humidity detection sensor 99 as humidity detection means according to the present invention are built in the image forming apparatus and detect the temperature and humidity around the image forming apparatus. The control means 95 has a built-in memory 95a, and a low-temperature and low-humidity reference value that serves as a reference for determining whether the environmental condition is low-temperature and low-humidity, and a high-humidity standard that serves as a reference for determining whether the environmental condition is high The value is stored.

  The paper feed position determining means 97 according to the present invention selects the paper feed position according to the type of the paper P by comparing the paper type and the paper feed position, and responds to it according to the ambient temperature and humidity. The program comprises a program for comparing the optimum sheet feeding position and selecting the sheet feeding position according to the temperature and humidity.

  When the temperature and humidity detected by the temperature detection sensor 98 and the humidity detection sensor 99 are both lower than the low temperature and low humidity reference value, the control unit 95 determines that the environmental conditions inside and outside the image forming apparatus are in a low temperature and low humidity state. . Then, the sheet feeding position is changed via a sheet feeding position determining unit and a sheet feeding position adjusting unit, which will be described later, to prepare for a no-feed that is likely to occur at low temperatures and low humidity. Specifically, by setting the paper feeding position where the paper P enters the inclined surface 100a of the inclined surface holding member 100 to a higher position, the resistance from the inclined surface 100a is reduced and the transportability of the paper is improved. It is something to enhance.

  Further, when the humidity detected by the humidity detection sensor 99 is higher than the high humidity reference value, the control means 95 determines that the environmental conditions inside and outside the image forming apparatus are in a high humidity state, and the paper feed position determining means and The paper feed position is changed via the paper feed position adjusting means to prepare for double feeding that is likely to occur at high humidity. Specifically, by setting the paper feeding position where the paper P enters the inclined surface 100a of the inclined surface holding member 100 to a lower position, the resistance from the inclined surface 100a is increased and the overlapping sheets are separated. This is to prevent double feeding.

  That is, the factors for determining the paper feed position include the type of paper P described above and the temperature and humidity according to the present invention, and the paper feed position determining means 97 according to the present invention performs an experiment combining these two factors. The data created based on this is held as a program.

  Further, the control board of the paper feed position adjusting means 101 according to the present invention is provided with a control circuit including a timer, and the paper feed position determined according to the type of the paper P is further reset to a position corresponding to the temperature and humidity. Can be set. For example, when resetting the paper feed position determined by the type of the paper P to a higher position, the time when the motors 60 and 70 rotate by operating the timer from when the actuator 90 detects the sensors Su, Ss, and Sd. It is the structure of extending. In other words, the stop position of the paper feed tray 52 is set to a higher position by extending the rotation time of the motors 60 and 70 with a timer. If you want to change the paper feed position you want to change according to the temperature and humidity to a lower position, set the paper feed position that is determined according to the paper type to a low overall position in advance. In this case, the position raised by the timer may be set as a predetermined paper feed position.

  According to the present invention, by changing the paper feed position according to the paper type, it is possible to cope with the difference in transportability depending on the paper type, and to change the paper feed position according to the ambient temperature and humidity. Thus, the occurrence of conveyance failure due to temperature and humidity can be suppressed.

  FIG. 6 is an enlarged cross-sectional view showing a configuration of a feeding unit 50B in the second embodiment of the paper feeding device of the present invention, and FIG. 6A is an enlarged cross-sectional view corresponding to FIG. 4 of the first embodiment. FIG. 6B is a view showing a modified example of the inclined surface holding member.

  Portions common to the first embodiment are denoted by the same reference numerals, and different points will be mainly described below. In the second embodiment, the inclined surface 200a of the inclined surface holding member 200 is a curved surface. The inclination angle of the inclined surface 200a becomes loose above the inclined surface holding member 200, that is, along the paper traveling direction. When the inclination angle at the predetermined paper feeding position Ps is θ0, when the paper used is thick paper or highly rigid paper, the paper is fed by the sensor Su so that the paper feeding position is located above the inclined surface 200a. The paper position Pu is set, and the inclination angle of the inclined surface 200a is θ1. In the case of thin paper or low-rigidity paper, the paper feed position is set to the paper feed position Pd using the sensor Sd so that the paper feed position is located below the slope 200a, and the inclination angle of the slope 200a is θ2. Become. Here, the inclination angle is set to satisfy θ2> θ0> θ1. When the height of the sheet by the sensors Su, Ss, and Sd is indicated by the paper feed position, the height of the paper by the sensor Sd is a low paper feed position indicated by Pd, and the inclination angle θ2 is increased. On the contrary, the height of the sheet by the sensor Su becomes a high paper feed position indicated by Pu, and the inclination angle θ1 becomes small. In other words, in the second embodiment, when the paper feed position of the paper P changes, the inclination angle θ of the inclined surface 200a with which the leading edge of the paper P abuts also changes.

  FIG. 6B is a schematic view showing a modified example of the inclined surface holding member. The inclined surface holding member 210 has an inclined surface 210a composed of three flat surfaces in which two intermediate portions are broken. Similar to the inclined surface 200a of FIG. 6A, the inclination angle of the inclined surface 210a is θ1, the lower is θ2, the middle is θ0, and θ2> θ0> θ1. When this inclined surface holding member 210 is used, the choice of which one of the inclination angles to use, θ0, θ1, or θ2, is used.

  In addition, the inventor, through the experiment, sets the inclination angles θ0, θ1, and θ2 of the inclined surfaces 200a and 210a of the inclined surface holding members 200 and 210 in the second embodiment to 0 ° as in the first embodiment. A good result is obtained by setting the angle in a range exceeding 90 ° and less than 90 °.

  According to the present embodiment, as in the first embodiment, the inclined surfaces 200a and 210a of the inclined surface holding members 200 and 210 are fixed, and the sheet P is conveyed at the contact position of the sheet P with the inclined surfaces 200a and 210a. It is not necessary to make the inclined surface 100a movable. Therefore, similar to the first embodiment, the configuration can be simplified, and a motor and a solenoid as a power source are not necessary, so that the manufacturing cost can be kept low.

  In addition, since more inclination angles can be set than in the first embodiment, it is possible to set a paper feed position that can cope with various change in conditions.

  In the second embodiment, there are three types of paper height and three sensors Su, Ss, and Sd are used. However, since the inclined surface 100a is a curved surface, the height of the paper P can be changed variously. The inclination angle can be finely changed to three or more. In that case, the number of sensors may be increased, but any one of the sensors Su, Ss, and Sd may be used, and the height of the sensor may be moved up and down by a movable sensor holding member. Further, by providing the encoder 68 on the support shaft portion 90a so that the inclination angle of the actuator 90b can be detected, the number of sensors can be reduced to one and a large number of paper heights can be set.

  FIG. 7 is a block diagram of a control system related to the operation when the paper feed position is changed by means including special means in the paper feeder of the present invention. Similar to the block diagram of FIG. 5, the paper height (paper feed position) is set by the sensors Su, Ss, and Sd, and the positions are indicated by Pu, Ps, and Pd in FIG. 4 or FIG.

  In FIG. 7, the temperature / humidity data from the temperature detection sensor 98 and the humidity detection sensor 99, the paper position information from the sensors 69 and 79 and the sensors Su, Ss, and Sd, and the paper data input from the input unit are as follows. This is the same as the block diagram of FIG. A characteristic configuration in FIG. 7 is that a paper feed time handling unit 111, a paper feed error handling unit 112, and a curl handling unit 113 are provided.

  The paper feed error handling means 112 according to the present invention counts the generated feed jams and double feeds, stores the frequency of occurrence, and when the frequency of occurrence exceeds a preset paper feed error frequency reference value, the paper feed position It is a means to change. This paper feed error handling unit 112 includes a jam detection sensor (not shown), a counter that counts the number of times of occurrence of feed jam detected by the jam detection sensor, and the frequency of occurrence of feed jam and an optimal paper feed position for preventing it. It consists of a program that contrasts with.

  This program is created based on experiments, and compares the occurrence frequency of feed jams and double feeds with the paper feed position to prevent it according to the type of paper. When there is a difference in the occurrence frequency of feed jam or double feed depending on the type of paper, when using paper with a high occurrence frequency of feed jam, in the first embodiment, in the first embodiment, the paper feed position is increased to Reduce the resistance. In the second embodiment, the sheet feeding position is increased in order to loosen the inclination angle. When using paper that is likely to be double-fed, in the first embodiment, the sheet feeding position is lowered to increase the resistance of the inclined surface, and in the second embodiment, the paper is fed to increase the inclination angle. Lower the paper position. It is judged by the control means 95 whether the frequency of occurrence of feed jam or double feed differs depending on the type of paper.

  When there is no difference depending on the paper type and the occurrence frequency of feed jam and double feed is high, the program increases the paper feed position when the occurrence frequency of feed jam is high, regardless of the paper, and the frequency of occurrence of double feed is high. When it is high, the sheet feeding position is made low.

  The paper feed time handling unit 111 according to the present invention is a unit that measures the paper feed time from when the feed roller 53 starts to feed the paper until it reaches the transport roller 56, for example. Therefore, there is an aim to prevent paper jam in advance. This time can be measured by providing a sheet position detection sensor (not shown) in the vicinity of each of the feed roller 53 and the transport roller 56. When the paper feed time from the feed roller 53 to the transport roller 56 is shorter than a preset paper feed time reference value as a lower limit, it is determined that the resistance to paper transport is too small. In the first embodiment, The sheet feeding position is lowered to increase the resistance of the inclined surface. In the second embodiment, the sheet feeding position is lowered so as to increase the inclination angle (increase θ). If the paper feed time is longer than a predetermined paper feed time reference value as an upper limit, it is determined that the resistance to paper conveyance is too large. In the first embodiment, the paper feed position is increased to increase the slope surface. Reduce the resistance. In the second embodiment, the sheet feeding position is increased so as to make the inclination angle loose (θ is decreased).

  The curl handling unit 113 according to the present invention detects the curl of the paper stored in the paper feeding device, and changes the paper feeding position when the curl size exceeds a preset paper curl reference value. is there. The curl correspondence unit 113 includes a curl measurement unit that measures the direction and size of the curl, and a program that compares the paper feed position corresponding to the direction and size of the curl. As the curl measuring means, for example, the configuration described in Patent Document 3 (Japanese Patent Application Laid-Open No. 2004-277114) can be used. That is, the height of the paper is measured by a rotatable arm that contacts the upper surface of the paper at a different position in the paper conveyance direction and an encoder that detects the amount of rotation of the arm, and the curl is calculated from the measured values at the different positions. It is the structure of calculating the direction and magnitude | size of. That is, from the measured values of the height of the leading edge and the central portion of the paper, the direction of the curl whether the paper is convex upward or downward and the size thereof can be determined. When the curl direction is an upwardly convex curl and the size is larger than the paper curl reference value, the paper has a large resistance at the front end of the paper against the inclined surfaces 100a, 200a, 210a, and there is a risk of causing no feed. high. Therefore, when the paper has an upwardly convex curl, the paper is brought into contact at a high position on the inclined surfaces 100a, 200a, and 210a, so that resistance to paper conveyance can be weakened and no feed can be prevented. Further, when the curl direction is a downwardly curled curl and the size is larger than the paper curl reference value, the bottom surface of the paper is slippery and double feeding is likely to occur. Therefore, when the paper has a downwardly convex curl, the paper is brought into contact with the inclined surfaces 100a, 200a and 210a at a low position, thereby increasing resistance to paper conveyance and preventing occurrence of double feeding.

  According to the present embodiment, it is possible to set an appropriate paper feed position according to paper conveyance failure or curl, and it is possible to improve the paper conveyance performance.

  FIG. 8 is a flowchart for explaining the procedure for changing the paper feed position in the paper feeder of the present invention.

  In FIG. 8, first, the paper P is loaded into the paper feeding device (step S11). Next, based on detection signals from the temperature detection sensor 98 and the humidity detection sensor 99, the control means 95 confirms whether or not the detected temperature and humidity are lower than a preset low-temperature and low-humidity reference value (step S12). . If it is lower than the low-temperature and low-humidity reference value (Yes at Step S12), the process proceeds to Step S13, and if not lower (No at Step S12), the process proceeds to Step S14.

  In step S13, the control means 95 operates the paper feed position determining means 97, the paper feed position adjusting means 101, and the motors 60 and 70 as the paper feed position changing means, so that the position of the paper P is moved from the predetermined paper feed position. The paper feed tray 52 is moved so as to be at a high position (step S13).

  If it is not lower than the low-temperature and low-humidity reference value, the process proceeds to step S14, and the control means 95 checks whether or not the detected humidity is higher than a preset high-humidity reference value (step S14). If it is higher than the high humidity reference value (Yes at Step S14), the process proceeds to Step S15, and if not higher (No at Step S14), the process proceeds to Step S16.

  In step S15, the control unit 95 operates the paper feed position determining unit 97, the paper feed position adjusting unit 101, and the motors 60 and 70 to feed the paper P so that the position of the paper P is lower than the predetermined paper feed position. The paper table 52 is moved (step S15).

  If it is not higher than the high humidity reference value, the process proceeds to step S16, and the control means 95 operates the paper feed position determining means 97, the paper feed position adjusting means 101, and the motors 60 and 70 so that the position of the paper P is a predetermined value. The paper feed table 52 is moved so as to reach the paper feed position (step S16).

  After the movement of the paper feed tray 52 is completed, the control unit 95 rotates the feed roller 53 to feed the paper P from the paper feed tray 52 (step S17).

  According to the present embodiment, it is possible to provide a paper feeding device that can automatically cope with ambient temperature and humidity, and an image forming apparatus including the paper feeding device.

10 Image forming apparatus main body 50 LCT50 (large capacity sheet feeding device)
50A Sending unit in the first embodiment 50B Sending unit in the second embodiment 52 Paper feed table (paper placement table)
53 Feeding roller (feeding means)
54 Feed roller 55 Rolling roller 56 Transport roller 60 Motor (paper feed position changing means)
69 sensor 70 motor (paper feed position changing means)
79 Sensor 90 Actuator 95 Control means 95a Memory 96 Input section 97 Paper feed position determination means 98 Temperature detection sensor (temperature detection means)
99 Humidity detection sensor (humidity detection means)
DESCRIPTION OF SYMBOLS 100 Inclined surface holding member 100a Inclined surface 101 Feeding position adjustment means 111 Feeding time correspondence means 112 Feeding error countermeasure means 113 Curling countermeasure means 200 Inclined surface holding member 200a Inclined surface 210 Inclined surface holding member 210a Inclined surface P Paper Pu Supply Paper position Ps Paper feed position (predetermined paper feed position)
Pd paper feed position Su sensor (paper feed position detection means)
Ss sensor (paper feed position detection means)
Sd sensor (paper feed position detection means)
θ, θ0, θ1, θ2, tilt angle

Claims (9)

A stack of sheets mounted as a bundle of sheets, a sheet mounting table that moves up and down, and
A paper feed position detecting means for detecting the uppermost paper in the paper bundle;
A paper feed position changing means for moving the paper mounting table so that the uppermost paper position of the paper bundle maintains a predetermined paper feed position based on the detection of the paper feed position detecting means;
Delivery means for delivering the uppermost sheet of the sheet bundle;
A paper feed roller for receiving the fed paper,
A double-rolling prevention roller that is in pressure contact with the paper feed roller;
An inclined surface holding member provided with an inclined surface between the paper feeding roller and the feeding means and overcoming the leading edge of the paper fed from the feeding means;
Temperature detection means and humidity detection means for detecting ambient temperature and humidity; and when the temperature and humidity detected by the temperature detection means and humidity detection means are lower than a preset low-temperature and low-humidity reference value, A paper feeding device that changes the uppermost paper position of the paper bundle to a position higher than the predetermined paper feeding position.   The uppermost sheet position of the sheet bundle is changed to a position lower than the predetermined sheet feeding position when the humidity detected by the humidity detecting unit is higher than a preset high humidity reference value. Item 2. The sheet feeding device according to Item 1.   2. The paper feed position determining means for storing a paper feed position adapted to the paper type, and changing the uppermost paper position of the paper bundle according to the type of paper used. Or the sheet feeding device described in 2.   A paper feed error handling means for counting the frequency of occurrence of paper feed errors, and when the frequency of paper feed errors counted by the paper feed error handling means exceeds a preset paper feed error frequency reference The sheet feeding device according to any one of claims 1 to 3, wherein the uppermost sheet position of the sheet bundle is changed. A paper feed time corresponding means for measuring a paper feed time from when the feed means starts feeding the top sheet of the paper bundle to a transport roller located downstream in the paper transport direction of the feed means; Have
5. The sheet feeding device according to claim 1, wherein the uppermost sheet position of the sheet bundle is changed according to the sheet feeding time.   6. The curl handling means for detecting the direction and size of the curl of the sheet is provided, and the uppermost sheet position of the sheet bundle is changed according to the detection result of the curl handling means. The sheet feeding device according to any one of the above.   The inclined surface of the inclined surface holding member is formed so that an angle between the inclined surface and a sheet abutting on the inclined surface is reduced along a traveling direction of the sheet. The sheet feeding device according to claim 1.   The sheet feeding device according to any one of claims 1 to 7, wherein an inclination angle between the inclined surface holding member and the sheet is more than 0 ° and less than 90 °.   An image forming apparatus comprising the paper feeding device according to claim 1.

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