JP2002160850A - Paper detection sensor and image forming device - Google Patents

Abstract

(57) [Problem] To provide a paper detection sensor for detecting a remaining amount of paper, which can prevent breakage when replenishing a paper bundle into a paper storage unit. A remaining amount sensor (paper) which is mounted on a first paper supply tray (paper supply device) on which a plurality of papers P are stacked and which detects the presence or absence of paper based on displacement of a filler 572 when the paper P comes into contact with the paper P. In the detection sensor 57, an opening h is formed in the vertical wall portion 49 that regulates the lateral displacement of the sheet bundle on the sheet feeding device,
The protruding end of the filler 572 is formed on the protruding curved surface Q, and the protruding curved surface Q is arranged so as to protrude from the opening h toward the sheet bundle to detect the remaining amount of sheets.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper detection sensor and an image forming apparatus, and more particularly, to a large-volume paper feeder provided with a mounting portion on which a large amount of paper bundles are stacked and a vertical wall portion for restricting lateral displacement of the paper bundle. The present invention relates to an image forming apparatus including therein a paper detection sensor and a large-volume paper feeding device.

[0002]

2. Description of the Related Art An image forming apparatus forms a desired image on a sheet through a sheet passing path from a sheet feeding section to a sheet discharging section, and forms a desired image on the sheet through the sheet passing path. FA
X and a printing device are known. In such an image forming apparatus, the size of sheets has been diversified with the increase in the number of functions, and the number of sheets on which continuous images are formed has also increased. For this reason, a plurality of types of paper feeding trays are dispersedly arranged in the paper feeding unit, and these paper feeding trays selectively operate to feed paper to the image forming process unit in the paper passing path.

[0003] In such a sheet feeding section, particularly, sheets of a large consumption amount are fed by a large-volume sheet feeding device which has an elevating function and can accommodate a large number of sheet bundles. When the large-volume paper feeder is for loading relatively small-sized paper, when the paper feeder is mounted in the main body of the apparatus, a dead space is often generated on the rear side. Therefore, in order to effectively use this space, a large-volume paper feeder adopting a paper feed tray side-by-side system in which a pair of paper storage units are horizontally arranged is known, and one example thereof is disclosed in JP-A-2000-108480. Have been.

In such a large-volume sheet feeding apparatus, FIG.
13A to 13C, the sheet feed tray 10
0, the first and second paper storage units 110 and 120 are provided side by side,
Each accommodation section has a pair of side fences 13 facing each other.
0 and 140 are provided, respectively, and a large number of sheets P are stacked between them without collapsing. Then, the paper P in the first paper storage unit 110 is sequentially sent out by a paper feed roller 170 to a paper passing path (not shown) at the time of paper feeding. When the mounting table 110a of the first sheet storage unit 110 reaches the upper end position as shown by a two-dot chain line in FIG.
The mounting table 110a is returned to the reference position shown by the solid line, and then the sheet in the second sheet accommodating section 120 is moved to the transfer pressing member 150.
, And is replaced on the first mounting table 110a, thereby enabling a large number of image forming processes.

By the way, as shown in FIGS. 13A to 13C, the side fence 140 of the second
Is provided with a pair of paper remaining amount detection sensors s1 at the top and bottom,
This makes it possible to detect the remaining amount of the stack of sheets in a stepwise manner and prepare for replenishment. Further, a paper end sensor s2 for detecting running out of paper is provided on the mounting table 120a,
This makes it possible to detect that the second sheet storage unit 120 has run out of sheets and prepare for replenishment.

[0006]

By the way, in the image forming apparatus, as the space is reduced, the sheet feeding tray 100 of the sheet feeding section is required.
Is narrowed, and accordingly, the space T between the first and second paper storage units 110 and 120 is also narrowed. When paper is set in the paper storage unit using the space, the paper setting Tends to be difficult to remove.

As shown in FIGS. 13 (a) to 13 (c), the remaining sheet detecting sensor s1 and the single-end sensor s2 of the second sheet accommodating section 120 have fillers s12 with respect to their sensor bases s11 and s21. , S22 are swingably mounted. These fillers s12, s2
2 is the vertical wall fv of the side fence 140 and the mounting table 1
The sheet 20a is arranged so as to protrude from the upper surface fh of the sheet 20a, and easily moves forward and backward in the sheet supply direction n1, which is the vertical direction in the case of the filler s12, and in the sheet supply direction n2 in the case of the filler s22. However, when the paper is moved in the directions m1 and m2 orthogonal to the paper movement directions n1 and n2, the fillers s11 and s21 receive a pressing force on the lateral surface, and may be damaged. Therefore, when replenishing the sheet bundle to the second sheet accommodating section 120, the machine user (operator) sets the sheet so as to be in a direction substantially close to the sheet moving directions n1 and n2 in order to avoid damage to the fillers s11 and s21. It is necessary to move the bundle to replenish the paper bundle in the second paper storage unit 120. At this time, the space T between the first and second paper storage units 110 and 120 is small, and it takes time to supply the paper. It will be.

An object of the present invention is to firstly provide a paper detection sensor for detecting a remaining amount of paper, which can prevent breakage at the time of replenishing a bundle of paper into a paper storage section. . Second, it is an object of the present invention to provide a paper detection sensor for detecting the presence / absence of a sheet, which can prevent breakage when replenishing a sheet bundle into the sheet storage unit.

Thirdly, it is an object of the present invention to provide a paper detection sensor for detecting the remaining amount of paper and detecting the presence or absence of paper which can prevent damage by optimizing the mounting angle of the filler when replenishing the paper bundle into the paper storage unit. And Fourth, claims 1 to 4
An image forming apparatus capable of performing a stable paper supply process (using a paper detection sensor capable of preventing breakage) by performing image formation control using the paper detection sensor described in any one of the above. Aim

[0010]

In order to achieve the above-mentioned object, the invention according to claim 1 is mounted on a paper feeder for stacking a plurality of sheets, and the displacement of the filler when the filler comes into contact with the sheets is determined. In a paper detection sensor that detects the presence or absence of paper, an opening is formed in a vertical wall portion that regulates lateral displacement of the paper bundle on the paper feeding device, and a protruding end of the filler is formed on a protruding curved surface, and the protruding curved surface is formed. The surface is disposed so as to protrude toward the sheet bundle side from the opening, and the remaining amount of sheets is detected. In this way, the protruding end of the filler of the paper detection sensor forms a protruding curved surface, which is arranged so as to protrude toward the paper bundle side from the opening of the vertical wall portion. Regardless of the direction in which the protruding curved surface comes into contact, the sheet bundle can slide smoothly while pressing the protruding curved surface, and damage to the filler of the paper detection sensor for detecting the remaining amount of paper can be prevented.

According to a second aspect of the present invention, there is provided a paper detection sensor mounted on a paper feeder for stacking a plurality of papers and detecting the presence or absence of a paper from displacement of a filler when the paper comes in contact with the paper. An opening is formed in a mounting portion for mounting a sheet bundle on the sheet, a protruding end of the filler is formed in a protruding curved surface, and the protruding curved surface is arranged so as to protrude from the opening toward the sheet bundle to cut out the sheet. It is characterized by detecting. In this way, the protruding end of the filler of the paper detection sensor forms a protruding curved surface, which is disposed so as to protrude toward the sheet bundle side from the opening of the mounting portion. It is possible to slide while pressing the protruding curved surface, and it is possible to prevent the filler of the paper detection sensor for detecting the presence or absence of paper from being damaged.

According to a third aspect of the present invention, in the paper detection sensor according to the first aspect, the mounting angle θ of the filler in a front view toward the opening of the vertical wall portion is set in the paper feeding direction of the paper feeding device. On the other hand, 0 <θ <90 ° is set. As described above, since the mounting angle θ of the filler of the paper detection sensor for detecting the remaining amount of paper is inclined within a range of less than 90 ° with respect to the paper feeding direction of the paper feeding device, the pressing force is applied from just beside the longitudinal direction of the filler. Can be reduced, and the filler can be prevented from being damaged when the sheet bundle is supplied.

According to a fourth aspect of the present invention, in the paper detecting sensor according to the second aspect, the mounting angle θ ′ of the filler in a front view toward the opening of the mounting portion is determined by changing a mounting direction θ of the paper feeding device. In contrast, 0 <θ ′ <90 ° is set. As described above, since the mounting angle θ ′ of the filler of the paper detection sensor for detecting the presence or absence of the paper is inclined within a range of less than 90 ° with respect to the paper feeding direction of the paper feeding device, the pressing force is applied from just beside the longitudinal direction of the filler. Can be reduced, and the filler can be prevented from being damaged when the sheet bundle is supplied.

According to a fifth aspect of the present invention, a desired image is formed on a sheet in the sheet passing path by passing the sheet through a sheet passing path from a sheet feeding section for loading a plurality of sheets to a sheet discharging section. In the image forming apparatus, the paper detection sensor according to any one of claims 1 to 4 is provided in the paper supply unit. An image forming apparatus according to the present invention is configured as described above.
Since the image formation control is performed using the paper detection sensor capable of preventing the damage described in any one of the above, an image forming apparatus capable of performing a stable sheet feeding process can be provided.

[0015]

1 and 2 show a large-volume paper feeder using a paper detection sensor according to a first embodiment of the present invention, and an image forming apparatus equipped with the same large-volume paper feeder as a paper supply unit. Electrophotographic copier (hereinafter simply referred to as copier) 1
Is shown. The copying machine 1 has an upper housing 501 and a lower housing 502 as housings, and a connecting means J comprising a pin hole J1 and a pin J2 which is inserted into the pin hole J1 without displacement in one or the other of the housings. (See FIG. 2) to be integrally connected vertically.

The lower housing 502 has a paper feeding unit 2 forming a paper feeding device.
And a lower paper passage route r extending from the paper supply unit. The upper housing 501 has a paper discharge unit 3, an upper paper passage path r from the paper supply unit 2 to the paper discharge unit 3, and an image forming process for forming a desired image on a sheet conveyed to the paper passage path r. The part 4 is mounted.

The image forming process section 4 of the copying machine 1 rotatably supports the photosensitive drum 6 on the upper housing 501 side, and surrounds the photosensitive drum 6 with a charger 7, an exposure device 8, and a developing device 9. The transfer device 10 and the cleaning device 11 are arranged, and a visible image is formed on the paper P by executing an electrophotographic image forming process including a charging process, an exposure process, a developing process, and a transfer process. After passing the process, the toner image is fixed on the sheet P of the transfer-receiving body by the fixing unit 30 on the sheet P. The sheet P after fixing is stored in a sheet discharge unit 3 including a sheet discharge tray. A main part of the exposure device 8 is provided above the photosensitive drum 6, and an automatic document feeder (ADF) 12 is provided on an upper wall of the upper housing 501.

The exposure device 8 includes an automatic document feeder (ADF) 1
A light source 14 for irradiating light to a document O placed on a contact glass 13 by a manual or manual operation, a mirror group 15 and a lens for exposing a reflected light image from the document O onto a photosensitive drum 6 It is composed of 16 exposure optical systems. The paper feed unit 2 is provided in the lower housing 502 of the copying machine 1, and the paper feed unit 2 is connected to the paper passing path r. A paper feed roller group 20, pickup rollers 21a and 21b, and a registration roller 22 are provided on a paper passage path r from the paper supply unit 2 to the paper discharge unit 3, and these are driven and controlled by control means (not shown). The conveyance of the sheet on the sheet passing path r can be controlled.

The paper supply unit 2 includes a first paper supply tray 17 as a large-volume paper supply device capable of stacking a bundle of paper P having a relatively small size.
And a second paper feed tray 18 capable of stacking relatively large-sized paper PL. The first paper tray 17 includes first and second paper storage units 23 and 24, and a pickup roller 21a is rotatably disposed above the first paper storage unit 23. Similarly, a pickup roller 21b is rotatably disposed above the second paper feed tray 18.

First paper feed tray 17 as a large-volume paper feeder
Are provided with first and second mounting tables 27 and 28 in the first and second sheet storage units 23 and 24, and sheets P of the same size are placed thereon.
Are formed so as to be loadable. The first mounting table 27 of the first sheet storage unit 23 is supported by the push-up mechanism 29 so as to be vertically movable in the first sheet feed tray 17.

As shown in FIGS. 1 and 4, the lifting mechanism 2
Reference numeral 9 denotes a motor M1 supported by the first paper tray 17, a pinion 291 rotated by the motor M1, and a guide rail 294 supported by the first paper tray 17 so as to be vertically slidable. And a rack 292 that is moved up and down by the controller. An arm 293 is integrally connected to the upper end of the rack 292, and the arm 293 is fitted to the fitting portion 271 of the first mounting table 27 to constitute a rack-and-pinion type push-up mechanism 29. It should be noted that the push-up mechanism 29 can be replaced with a pantograph-type or chain-driven lifting mechanism (not shown) instead of the rack-and-pinion type.

In the vicinity of the pickup roller 21a shown in FIG. 1, a separation roller pair 32 composed of a driving roller 32a and a driven roller 32b is provided. The pickup roller 21a and the drive roller 32a are rotatably supported by a bracket 33, as shown in FIG. The bracket 33 is provided on the support shaft 32 of the drive roller 32a.
One end of a tension coil spring 34 is attached to an end on the side opposite to the side supporting the pickup roller 21a, swingably supported by a side plate (not shown) of the lower housing 502 around the center c. A pulley 35 is attached to the pickup roller 21a, and a double pulley 32d is attached to the drive roller 32a.
An endless belt 36 for transmitting a driving force from a motor M2 provided in the lower housing 502 is stretched over d, and an endless belt 37 is stretched between each pulley 35 and 32d.

The other end of the extension coil spring 34 has a lower housing 5
A rack 39 supported vertically movably is attached to the side plate 02, and a stepping motor M3 having a pinion 38 meshing with the rack 39 on its output shaft is provided near the rack 39. With this configuration, when the stepping motor M3 rotates and the rack 39 moves upward, the bracket 33 swings counterclockwise around the support shaft 32c, and the sheet feeding pressure of the pickup roller 21a on the sheet P increases. .

As shown in FIG. 5, the driven roller 32b is supported vertically and rotatably by a guide member (not shown) provided on the lower housing 502.
One end of a compression coil spring 42 is attached to 2e. The other end of the compression coil spring 42 is attached to a rack 43 supported on a side plate (not shown) of the lower housing 502 so as to be vertically movable. Near the rack 43, a pinion 44 meshing with the rack 43 on its output shaft is provided. Is provided. With this configuration, when the stepping motor M4 rotates and the rack 43 moves upward, the compression coil spring 42 is compressed, and the separation pressure of the driven roller 32b with respect to the drive roller 32a increases.

As shown in FIGS. 1 and 3, a pair of side fences 45 for guiding the sheet P in the width direction and the uppermost part of the sheet bundle on the first sheet accommodating section 23 are provided on the first mounting table 27. A first paper end detection sensor 41 is provided which detects when the paper is out of contact with the paper and turns on the paper. A guide wall 46 which is a vertical wall for aligning the leading edge of the paper of the first mounting table 27 is formed at one end of the first paper feed tray 17 facing the sandwiching space of both side fences 45.

As shown in FIGS. 1, 3 and 6 (a) to 6 (c), the second sheet accommodating section 24 has a second mounting table 28, which is fixed in the first sheet feeding tray 17. ing. When the paper P on the first mounting table 27 is used up, the paper P on the second mounting table 28 is stored in the second paper storage section 24.
Paper moving means 48 for moving the paper P in one direction, side fences 49 for regulating the width of the paper P in the width direction, and a second paper end detection sensor 51 for detecting the presence or absence of the paper P on the second paper feed tray 29. And a remaining amount detection sensor 57 for detecting the remaining amount of the paper P on the second paper storage unit 23.

As shown in FIGS. 6A to 6C, the second
A pair of paper remaining amount detection sensors 57 are vertically arranged on one side fence 49 of the paper storage unit 23 so that the remaining amount of the stacked paper bundle is stepwise (here, u1 area, u2 shown in FIG. 6C). Area (the three stages of the area u3)) to prepare for replenishment. Further, a second paper end detection sensor 51 is provided on the second mounting table 28, and thereby,
It is possible to detect the running out of the sheet in the second sheet storing section 23 and prepare for replenishment.

Here, as shown in FIGS. 6A to 6C, the remaining paper amount detecting sensor 57 and the second paper end detecting sensor 51 of the second paper storing section 24 are arranged with respect to their sensor bases 571 and 511. The fillers 572 and 512 are swingably attached, and a contact portion 57 having a spherical surface Q that is a bulging curved surface is provided at the tip of each of the fillers 572 and 512.
3, 513 are integrally formed.

Sensor base 57 of remaining amount detection sensor 57
Numeral 1 is tightened and coupled near the outside of the through-hole-shaped opening h provided in the side fence 49, the filler 572 is loosely fitted into the opening h, and the tip side of the contact portion 573 is separated from the vertical wall fv of the side fence 49 by a predetermined amount. It is protruded and mounted so as to contact the sheet bundle side by t. In particular, the filler 572 has a mounting angle θ of 45 ° in front view toward the opening h with respect to the sheet sending direction S (here, the horizontal direction) of the large-volume sheet feeding device.
Is set to Thereby, the second paper storage unit 120
When the sheet bundle is supplied along the vertical wall surface fv of the side fence 49, the tip of the filler 572 forms a spherical surface Q. Therefore, even if the sheet bundle abuts in any direction,
This allows the sheet bundle to smoothly retreat into the opening and allow sliding contact of the sheet bundle. In addition, the filler 572 that holds the attachment angle θ set at 45 ° with respect to the sheet sending direction y moves the sheet bundle at the time of replenishment substantially from above, that is, descends,
Even when the sheet abuts against the filler 572, the downward direction of the filler 572 is at an angle that avoids a direction perpendicular to the longitudinal direction of the filler 572, so that the bending of the filler 572 in the perpendicular direction can be reduced. Can be reduced and breakage can be prevented.

Similarly, the second paper end detection sensor 5
The first sensor base 511 is fastened and coupled to a position near the lower side of the through-hole-shaped opening h provided in the second mounting table 28, the filler 512 is inserted into the opening, and the distal end side of the contact portion 513 is connected to the second mounting table 28. Is mounted so as to protrude from the upper surface fh by a predetermined amount t. In particular, the mounting angle θ of the filler 512 toward the opening h when viewed from the front is set to 45 ° with respect to the sheet feeding direction y of the large-volume sheet feeding device. This allows
The first, which is obliquely above the upper surface fh of the second mounting table 28,
And a case where the sheet bundle descends obliquely downward along the vertical wall fv of the side fence 49 from the space T side between the second sheet accommodating sections 23 and 24, and is stacked and replenished on the second table 28. Since the tip of the filler 512 forms the spherical surface Q, even if the sheet bundle abuts from any direction,
The sheet bundle smoothly retreats into the opening, and the stacking after the movement of the sheet bundle can be tolerated. Moreover, the filler 512 holds the attachment angle θ ′ set at 45 ° with respect to the sheet sending direction y.
Since the sheet bundle at the time of replenishment descends from almost obliquely above and comes into contact with the spherical surface Q, the angle of the downwardly obliquely upward direction is set so as to avoid going perpendicular to the longitudinal direction of the filler 512. It is possible to prevent the filler 512 from receiving a pressing force from right beside and to bend or break in a right angle direction, and also to prevent the filler 512 from bending or breaking in a right angle direction even during paper feeding.

In the above description, the mounting angle θ of each of the fillers 572 and 512 of the remaining amount detection sensor 57 and the second paper end detection sensor 51 is set to be inclined upward by 45 ° with respect to the paper sending direction y. The attachment angle θ may be set so as to be inclined downward by 45 ° with respect to the sheet sending direction S.
May be set at an angle of 45 ° up and down in the opposite direction. Furthermore, the mounting angles θ and θ ′ of the fillers 512 and 572 are set to 45 °, but are not limited to this, and the mounting angles θ are each set to 0 ° <0 °.
θ (, θ ′) can be set to a value within the range of 90 °, and in these cases, similarly, the bending of the fillers 512 and 572 can be reduced and breakage can be prevented.

The paper moving means 48 has a guide elongated groove 53 (see FIG. 8) formed at the center of the second mounting table 28, and a slider-like slidably mounted along the guide elongated groove 53 so as not to be detached. It is formed by a sheet moving member 481 and a feed screw mechanism (not shown). The sheet moving member 481 moves the sheet P bundle of the second mounting table 28 to the first mounting table 2 by the pressing operation.
7 can be pressed and moved. In this case, the boss 481 at the bottom of the sheet moving member 481 (see FIG. 6C).
Is provided with a feed screw mechanism (not shown), and the drive of the feed screw mechanism is controlled by control means (not shown) via a motor (not shown).

A separation roller pair 54 composed of a driving roller 54c and a driven roller 54b is disposed near the pickup roller 21b facing the second paper feed tray 18 on which large-sized sheets PL can be stacked. Each roller 2
1b, 54c, and 54b are rotatably supported by a bracket (not shown) supported on the lower housing 502 so as to be swingable about a support shaft (not shown), and driven by a motor (not shown) provided on the lower housing 502. It is driven to rotate by receiving force.

Further, the second paper feed tray 18 is provided with a push-up mechanism (not shown) which operates in conjunction with the mounting of the tray, whereby the paper PL is picked up by the pickup roller 21b.
It is formed so that it can be pressed. Further, a third paper end detection sensor 56 (see FIG. 1) that contacts the sheet P and detects the presence or absence of the sheet PL on the second sheet tray 18 is provided on the second sheet tray 18.

When the image forming operation is started in the image forming process section 4 during the operation of the copying machine 1 shown in FIG. 1, the photosensitive drum 6 is charged by the charging charger 7, and the original image from the exposure device 8 is exposed. Thus, an electrostatic latent image is formed. This electrostatic latent image is developed by a two-component developer or a one-component developer of the developing device 9 to be visualized, and a toner image is formed on the photosensitive drum 6 of the image carrier. The toner image is transferred by the transfer device 10 to sheets P and PL conveyed along a sheet passing path r from a sheet feeding unit 2 described later, and the transferred sheet P is fixed with the toner image by the fixing unit 30. Paper output unit 3
Is stored in.

Prior to this, the control means (not shown)
First and second paper storage units 23 and 24 in paper feed tray 117
The presence or absence of the upper paper P is detected by the first and second paper end detection sensors 41 and 51, and the presence or absence of the paper on the second paper feed tray 18 is detected by the third paper end detection sensor 56.

Here, when all the sheets P are properly stacked, the control means is kept in a sheet feeding standby state, and starts driving the above-described image forming process unit 4 in response to a copy command.

When it is detected that there is no paper P on the first mounting table 23 of the first paper tray 17 and no paper PL on the second paper tray 18, the control means displays a message indicating that the paper has run out. Paper is supplied to each tray.

Here, the first paper feed tray 17 is provided as shown in FIG.
As shown in (a), the first and second mounting tables 2 are set in advance.
An appropriate amount of the sheet P bundle is set on each of the sheets 7 and 28.
Then, by setting the first sheet tray 17 on the lower housing 502, the sheet bundle on the first mounting table 27 is lifted by the lifting mechanism 29, and the upper end of the sheet bundle is picked up by the pickup roller 2.
The lift process is performed until the copy machine 1a comes into pressure contact with the copy machine 1a, and the copying machine 1 is set in a paper feed standby state.

When the consumption of the paper P progresses and the paper P on the first mounting table 23 of the first paper feed tray 17 runs out as shown in FIG. 7B, the control means (not shown) controls the first mounting table 27 to move. Then, as shown in FIG. 7C, it is held in a state of being parallel to the second mounting table 28. In this state, the operator operates as shown in FIG.
As shown in (d), the paper moving member 48 is
3 and is pushed toward the first mounting table 27 side, and the second mounting table 28 is pressed.
Is moved to the first mounting table 27, the paper moving member 48 is returned to the original standby position, and then a sheet bundle is supplied to the second mounting table 28.

Thereafter, the first paper feed tray 17 is moved to the lower housing 50.
2, the control means (not shown) detects the sheet setting, drives the push-up mechanism 29, and performs a lifting process until the upper end of the sheet P bundle comes into pressure contact with the pickup roller 21a as shown in FIG. .

At the time of replenishing the sheet bundle to the second table 28, the sheet bundle is placed on the upper surface fh of the second table 28 from above the space T between the first and second sheet storage units 23 and 24. Descends obliquely downward and is loaded on the second mounting table 28. At this time, even if the sheet bundle abuts the spherical surface Q at the tip of the filler 512 protruding from the vertical wall surface fv of the side fence 49 from any direction, the bundle of sheets smoothly retreats into the opening and further in the sheet sending direction y. On the other hand, the filler 512 that holds the attachment angle θ set to 45 ° is an angle that avoids going perpendicular to the longitudinal direction of the filler 512 when the sheet bundle at the time of replenishment descends obliquely from above. In addition, it is possible to prevent the filler 512 from bending in the right-angle direction and prevent the filler 512 from being damaged.

Similarly, even if the sheet bundle at the time of replenishment descends from almost obliquely above and comes into contact with the spherical surface Q of the second paper end detection sensor 51 protruding from the opening h of the second mounting table 28, it is obstructed from obliquely above. Since the descending direction is at an angle that avoids being perpendicular to the longitudinal direction of the filler 512,
The filler 512 can be prevented from being bent or damaged. A copier (image forming apparatus) having a first paper feed tray 17 (large-volume paper feeder) using a remaining amount detection sensor 57 and a second paper end detection sensor 51 having such a breakage prevention function in a paper supply unit. 1) can perform a stable sheet feeding process during image formation.

FIGS. 10 and 11 show a stencil printing apparatus 60 as an image forming apparatus according to another embodiment of the present invention. The stencil printing apparatus 60 has a paper feeding unit 62 provided at a lower portion of a housing 61 and a paper discharging unit 63 provided at an upper portion of the housing 61, and a paper passing path extending from the paper feeding unit 62 to the paper discharging unit 63. r, an image forming process unit 64 is provided in the paper passing path r, and the image forming process unit 64 performs a printing process on the paper P. Here, the paper feeding unit 62 is the
The same configuration as that of the sheet feeding unit 2 of FIG.

The stencil printing apparatus 60 has a cylindrical plate cylinder 65 therein, and a master 66 made by the stencil is attached to the peripheral surface of the plate cylinder 65 by a detachable mechanism (not shown).
6, an ink supply mechanism disposed inside the plate cylinder 65
(Not shown), the ink is supplied to the surface of the master 66, and the master 66
The ink is transferred through the perforations.
The plate cylinder 65 is driven to rotate by a drive motor 67 in a direction indicated by an arrow. The plate cylinder 65 is provided with a configuration for starting the feeding of the paper from the paper supply unit 62 by the pickup roller 21a or the like. This configuration is based on the shielding member 6 provided on the peripheral surface of the plate cylinder 65.
8 and a paper feed roller trigger sensor 69 arranged in the movement path of the shielding member 68.

The paper feeding section 62 for feeding the paper P to the plate cylinder 65 is provided in the feeding direction of the paper P indicated by an arrow A.
The pickup roller 21a, the sheet feed roller group 20, the registration unit 71, and the sheet pressing unit 72 are arranged in this order from the upstream side. The structure for discharging the sheet P includes a separation claw 73, a pair of discharge rollers 74, and a discharge tray-shaped discharge tray disposed behind the plate cylinder 65 corresponding to the downstream side of the plate cylinder 65 in the sheet feeding direction. It is constituted by a paper section 63. The separation claw 73 separates the paper P stuck to the master 66 of the plate cylinder 65 with ink.
The sheet P peeled off by the separation claw 73 is
4, the paper is conveyed by a pinch and is discharged to a paper discharge section 63 in the form of a discharge tray.

The paper supply unit 62 includes a first paper supply tray 17 serving as a large-volume paper supply device for accommodating the first and second paper storage units 23 and 24 capable of stacking paper P of the same size.
L, a pickup roller 21a for picking up the sheet P in the first sheet storage unit 23 in the first sheet supply tray 17, and a pickup roller 21b for picking up the sheet P in the second sheet supply tray 18. Each of the PLs is sent to the registration unit 71 of the paper passing path r.

The registration section 71 is composed of a pair of rollers opposed to each other with the conveyance path of the sheet P interposed therebetween. The lower registration roller 71a located on the lower side of the conveyance path is configured to rotate by transmitting the rotational force from the drive motor 67 of the plate cylinder 65, and is rotated by the upper registration roller 71b.
Is configured to be able to be periodically contacted and separated by a driving force from a driving motor 67 via a displacement mechanism (not shown). The contact timing of the lower registration roller 71a is
For example, the profile of a cam provided in the displacement drive mechanism is set so that the leading end of the sheet P fed from the pickup roller 21a contacts the upper registration roller 71b before reaching the registration section 71. When the rotational force from the drive motor 67 is transmitted after the lower resist roller 71a comes into contact with the lower resist roller 71a and the lower resist roller 71a starts rotating, the upper resist roller 71b rotates.

During operation of the stencil printing apparatus 60, a control unit (not shown) drives the drive motor 67 in accordance with a print command, and for example, drives the pickup roller 21a.
To the first sheet feed tray 17
The sheet P of the first sheet storage section 23 is sent out, and it is determined whether or not the passage of the leading edge of the sheet is detected by the sheet passage sensor 74. The image is transferred from the master 66 to the sheet P that has received the image transfer at an appropriate timing, and is discharged to the sheet discharge unit 63.

The first paper feed tray 1 of the stencil printing machine 60
7, when the sheet bundle is supplied to the second mounting table 28 in the same manner as the sheet feeding section 2 in the copying machine 1 in FIG. 2 mounting table 28
The sheet bundle descends obliquely downward with respect to the upper surface fh of
It is loaded on the second mounting table 28. At this time, fillers 512 protruding from the vertical wall surface fv of the side fence 49
No matter which direction the sheet bundle abuts on the spherical surface Q at the tip of 572, the fillers 512 and 572 that can smoothly retreat into the opening h and maintain the attachment angles θ and θ ′
Deflection in a direction perpendicular to the longitudinal direction is reduced, and breakage can be prevented. Similarly, the second paper end detection sensor 51 protruding from the opening h of the second mounting table abuts on the spherical surface Q of the sheet bundle at the time of replenishment substantially obliquely from above. The fillers 512 and 572 that can retreat inside and that maintain the attachment angle θ are prevented from bending in a direction perpendicular to the longitudinal direction, and can be prevented from being damaged.

The remaining amount detection sensor 57 and the second paper end detection sensor 51 having such a damage prevention function are provided.
The stencil printing apparatus 60 of FIG. 10 can perform a stable sheet feeding process during printing by providing the stencil printing apparatus 60 with the first sheet feeding tray 17 (sheet feeding unit) using the stencil printing apparatus.

In the copying machine 1 and the stencil printing apparatus 60 described above,
The second paper storage unit 2 in the first paper tray 17 used there
8 has a contact portion 57 having a spherical surface Q that is a bulging curved surface at the tip of these fillers 572, 512.
3 to detect that the second sheet storage section 23 has run out of sheets. Instead, as shown in FIGS. 9A and 9B,
The contact portion 573a of the conical surface Qa, which is a bulging curved surface, is provided at the leading end of the filler 572 of the paper remaining amount detection sensor 57 (the second paper end detection sensor 51 can also have the same configuration).
May be provided.

Even when such a contact portion 573a of the conical surface Qa is used, the contact portion 573a of the conical surface Qa smoothly slides against a bundle of sheets from any direction so that the sheet bundle can be retracted and the remaining paper amount can be detected. Damage to the sensor 57a and the second paper end detection sensor 51a can be prevented.

As described above, the image forming apparatus is the copier 1
Although the present invention has been described as a stencil printer 60, the present invention is not limited to this, and the present invention may be applied to a facsimile, a digital copying machine, or the like.
The same operation and effects as those of the stencil printing machine 60 can be obtained.

[0055]

As described above, according to the first aspect of the present invention, the protruding end of the filler of the paper detection sensor forms a protruding curved surface, which is disposed so as to protrude from the opening of the vertical wall toward the paper bundle. When the sheet bundle is replenished into the sheet storage section, the sheet bundle can slide smoothly while pressing the projecting curved surface regardless of the direction in which the sheet bundle contacts the projecting curved surface, and the remaining amount of paper is detected. Of the filler of the paper detection sensor can be prevented. According to the second aspect of the present invention, the protruding end of the filler of the paper detection sensor forms a protruding curved surface and is disposed so as to protrude toward the sheet bundle side from the opening of the mounting portion. The sheet bundle can slide while pressing the projecting curved surface, and damage to the filler of the sheet detection sensor for detecting sheet presence can be prevented.

According to the third aspect of the present invention, since the mounting angle θ of the filler of the paper detecting sensor for detecting the remaining amount of the paper is inclined within a range of less than 90 ° with respect to the paper feeding direction of the paper feeding device, the filler in the longitudinal direction of the filler. On the other hand, it is possible to reduce the pressing force from just beside, and it is possible to prevent the filler from being damaged when the sheet bundle is supplied.

According to the fourth aspect of the present invention, since the mounting angle θ of the filler of the paper detection sensor for detecting the presence or absence of the paper is inclined within a range of less than 90 ° with respect to the paper feeding direction of the paper feeding device, Thus, it is possible to reduce the application of the pressing force from right beside, and it is possible to prevent the filler from being damaged when the sheet bundle is supplied. According to a fifth aspect of the present invention, in the image forming apparatus according to the first aspect,
Since the image formation control is performed using the paper detection sensor capable of preventing the damage described in any one of Items 4 to 4, it is possible to provide an image forming apparatus capable of performing a stable sheet feeding process.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a main part of a copying machine provided with a paper detection sensor and a large-volume paper feeder to which the paper detection sensor is attached according to an embodiment of the present invention.

FIG. 2 is an exploded perspective view showing an appearance of the copying machine shown in FIG.

FIG. 3 is a schematic perspective view of a main part of a first sheet feed tray attached to the copying machine of FIG. 1;

FIG. 4 is an enlarged configuration diagram of a lifting mechanism used by a first sheet feeding tray in FIG. 1;

FIG. 5 is an enlarged configuration diagram of a support mechanism of a pickup roller used by a first sheet feed tray in FIG. 1;

FIGS. 6A and 6B show first and second mounting tables of a first paper feed tray in FIG. 1, wherein FIG. 6A is a plan view of a cutaway of a main part, FIG. Shows a cutaway side sectional view of a main part.

FIGS. 7A and 7B are explanatory diagrams of the operation of the first and second mounting tables of the first paper feeding tray in FIG. 1, wherein FIG. 7A illustrates a paper feeding standby state, and FIG. , (C) shows the state of completion of the lowering of the first mounting table, (d) shows the state of paper transfer, and (e) shows the paper supply standby state after paper supply to the second paper supply tray.

FIG. 8 is a perspective view illustrating sheet bundle replenishment of a second sheet storage unit of a second sheet feed tray in FIG.

9A and 9B show a remaining amount detection sensor as another embodiment of the present invention, wherein FIG. 9A is a front view, and FIG. 9B is a side sectional view.

FIG. 10 is a schematic diagram illustrating a main part of a stencil printing machine to which a sheet feeding device according to another embodiment of the present invention is attached.

11 is a perspective view showing the appearance of the stencil printing machine of FIG.

FIGS. 12A and 12B show first and second sheet storage portions of a conventional large-volume sheet feeding device, wherein FIG. 12A is a plan view and FIG. 12B is a side sectional view.

13A and 13B show first and second sheet storage units of a conventional sheet feeding device, wherein FIG. 13A is a plan view of a cutaway main part, FIG. 13B is a front sectional view of a cutaway main part, and FIG. 2 shows a cutaway side sectional view.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Copier 17 1st paper feed tray (paper feed device) 21a Pickup roller 24 2nd paper accommodation part 28 2nd mounting table 49 Vertical wall part 51 Paper end detection sensor 57 Remaining amount detection sensor 512, 572 Filler 60 Stencil printer θ, θ 'Mounting angle h Opening r Paper passing path P Paper Q Projecting curved surface

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3F048 AA01 AB01 BA01 CB13 DC03 EB02 3F343 FA02 FB01 GA01 GB01 GC01 GD01 GE02 HA16 HB04 HC28 HD16 JA01 JD09 KB03 KB20 LA04 LA14 LA15 MA02 MA24

Claims (5)

[Claims] 1. A paper detection sensor mounted on a paper feeder for stacking a plurality of papers and detecting the presence or absence of a paper based on displacement of a filler when the paper bundle comes in contact with the paper, wherein: An opening is formed in a vertical wall portion that regulates lateral displacement, a protruding end of the filler is formed in a protruding curved surface, and the protruding curved surface is arranged so as to protrude toward the sheet bundle side from the opening to detect the remaining amount of paper. A paper detection sensor characterized in that: 2. A paper detection sensor mounted on a paper feeder for stacking a plurality of papers and detecting the presence or absence of a paper based on displacement of a filler when the paper bundle comes in contact with the paper, wherein the paper bundle is loaded on the paper feeder. An opening is formed in the mounting portion to be placed, a protruding end of the filler is formed in a protruding curved surface, and the protruding curved surface is arranged so as to protrude from the opening to the sheet bundle side to detect out of paper. Paper detection sensor. 3. The paper detection sensor according to claim 1, wherein the mounting angle θ of the filler in a front view toward the opening of the vertical wall portion is set with respect to a paper feeding direction of the paper feeding device.
A paper detection sensor, wherein 0 <θ <90 ° is set. 4. The paper detection sensor according to claim 2, wherein the mounting angle θ ′ of the filler as viewed from the front toward the opening of the mounting portion is 0 <0 with respect to the paper feeding direction of the paper feeding device. A paper detection sensor characterized by setting θ ′ <90 °. 5. An image forming apparatus for passing a sheet through a sheet passing path from a sheet feeding section on which a plurality of sheets are stacked to a sheet discharging section and forming a desired image on the sheet on the sheet passing path. An image forming apparatus comprising the paper detection sensor according to any one of claims 1 to 4, mounted on the paper supply unit.