JPH0826499A - Paper feeder for image forming device - Google Patents

Abstract

PURPOSE:To realize the display of a paper feed performance by push-pressing paper sheets against a pick up roller by means of fixed force by conducting the regulation of an ascent position by means of a paper sheet height control member in regard to a paper sheet mounting plate to be mounted with paper sheets inside a paper feed tray. CONSTITUTION:In the case of a paper sheet mounting plate 10 to support paper sheets P inside a paper feed tray, a swing arm member 20 is arranged at its side portion, and engage-stopping retension is carried out at the rack 22 of the swing arm member 20. A paper sheet height control member 15 for controlling height in regard to the paper sheets P supported on the paper sheet mounting plate 10 is arranged, and a detection member 16 to detect the height of the paper sheets P is arranged at one end portion of an upper part arm member 17, and a head responding member 19 to swing the swing arm member 20 is arranged at the other end portion, and the ascent height of the paper sheets P is regulated, and at the same time a means to maintain fixedly normal force between the pickup roller of a paper feed member and the paper sheets P is constituted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as an electrophotographic copying machine or a laser beam printer, which controls an ascending position of a sheet in a sheet feeding tray arranged in a sheet feeding section. The present invention relates to a sheet feeding device of an image forming apparatus that enables an upper surface of a sheet supported by a placing plate to be held with a pickup roller of a sheet feeding member maintaining a constant pressing force (normal force).

[0002]

2. Description of the Related Art In an image forming apparatus such as an electrophotographic copying machine or a laser beam printer, a paper accommodating means such as one or a plurality of paper feeding trays is arranged in a paper feeding section, and the paper accommodating means is arranged in the paper accommodating means. By accommodating sheets of different sizes and the like, it is possible to feed sheets of any size according to the size of the document. A device such as a paper feed tray arranged in the paper feed unit of the image forming apparatus is generally disclosed in Japanese Patent Laid-Open No.
As shown in Japanese Patent Publication No. 279126, there is provided a means for urging a sheet placing plate on which a sheet is placed in a rising direction by a spring. Then, the sheet is pressed against the pickup roller of the sheet feeding member, and the pickup roller is rotated so that the sheet can be sent out from the tray.

Further, in a paper feed tray capable of accommodating a very large number of sheets, as shown in Japanese Patent Laid-Open No. 3-205226, a plate member for supporting the sheets can be moved up and down via a supporting wire. It is provided in. Then, by driving the wire using a winding device, the support plate member is raised to constitute a mechanism for pressing the paper against the pickup roller. In the above-mentioned sheet feeding member arranged on the sheet feeding side of the sheet feeding tray, a pickup roller for taking out the sheet and a sheet separating device are arranged, and the sheets fed out from the sheet feeding tray are separated and fed one by one. Constitutes a means. A paper feed tray of the type in which the paper loading plate is moved up and down by a wire or the like is generally an apparatus using an elevator tray. In the elevator type paper feed tray, for example, a large number of papers of 1000 or more are loaded. It can be placed on a plate. Therefore, when using the paper feed tray of the paper support system as described above,
Even in a device such as an electrophotographic copying machine, which has an extremely large number of copies to be made per unit time, it is possible to make continuous copies by reducing the number of times of paper supply.

A sheet feeding tray provided in a relatively small copying machine or the like in addition to the sheet feeding tray and the sheet feeding device using the sheet feeding member as described above is disclosed in, for example, Japanese Utility Model Laid-Open No. 58-131234. As shown, it is also practiced to configure a paper separating device using a snubber claw. Then, by using a paper separating device in combination with the above-mentioned paper feeding tray, it is possible to feed the paper one by one while preventing the double feeding of the paper.

In the conventional sheet feeding device as described above, the frictional force between the sheet and the pickup roller is kept constant by keeping the force that the upper surface of the sheet presses against the pickup roller of the sheet feeding member. Therefore, it is necessary to maintain the sheet feeding performance and to exhibit the good paper feeding performance. Therefore, for example, in the above-mentioned elevator type paper feed tray, means for constantly detecting the position on the paper supported by the paper placing plate is provided, and when the position of the upper surface of the paper falls below the set position, the paper is immediately placed. The operation of raising the platen is performed, and the normal force between the upper surface of the paper and the pickup roller is controlled to be kept constant. Further, in the sheet feeding device using the snubber claws, the spring is arranged on the lower surface of the sheet placing plate to configure the means for raising the sheet. By arranging them, the sheet is prevented from being strongly pressed against the pickup roller by more than the set value.

[0006]

In a small-sized image forming apparatus, in order to reduce the overall manufacturing cost of the apparatus, the structure of the sheet feeding apparatus is simplified and one type of sheet feeding tray is used. It is desired to be configured to accommodate sheets of any size. However, when a plurality of types of paper are stored in the paper feed tray and a means for raising the paper placement plate by a spring is provided, when a large size paper is stored and a small size paper is stored. There is a problem that the weight of the paper is greatly different from the case where the paper is stored. In addition, the amount of paper stored in the tray gradually decreases during the operation of feeding the paper, so that the weight applied to the spring changes. And
Even when a means for raising the sheet loading plate by a spring is configured, the force for pressing the sheet against the pickup roller is constantly changed by the spring, and there is a problem that the normal force is not constant. Also has a big impact on.

In order to solve the above problems,
For example, as shown in Japanese Patent Application Laid-Open No. 3-288736, disposing a pushing-up means driven by a motor or the like to raise the sheet placement plate is also one method. However, controlling the drive device for pushing up the sheet placing plate not only complicates the configuration of the sheet feeding device, but also significantly affects the manufacturing cost of the sheet feeding device. Further, in the case of a paper feed tray containing a relatively large number of sheets of paper, using the elevator type paper feed tray
It is considered to be the best method for maintaining a constant normal force between the paper and the pickup roller and stabilizing the paper feeding performance, but it is not a good measure in terms of cost.

[0008]

It is an object of the present invention to solve the above-mentioned problems of the conventional paper feeding apparatus, and to raise the position of the paper with respect to the paper feeding tray using a spring as a means for pushing up the paper placing plate. By arranging a paper height control member provided with a means for detecting and a means for locking and holding the paper stacking plate at the rising position, by restricting the rising position of the paper stacking plate,
An object of the present invention is to provide a paper feeding device that can set a normal force between a pickup roller and paper to a constant value.

[0009]

SUMMARY OF THE INVENTION According to the present invention, there is provided a means for arranging a sheet feeding member corresponding to a sheet feeding portion of a sheet feeding tray, and feeding sheets stored in the sheet feeding tray one by one by the sheet feeding member. The sheet tray is provided with a sheet placing plate on which a sheet is placed, and a biasing means for raising a sheet feeding side end of the sheet placing plate, and a sheet placed on the sheet placing plate. The present invention relates to a sheet feeding device including means for pressing a predetermined force between the upper surface of the sheet feeding roller and the pickup roller of the sheet feeding member.
In the present invention, a paper height control member for adjusting the rising position is arranged on the paper placing plate that supports the paper inside the paper feed tray, and the paper height control member is used to raise the paper. It is composed of a detection member for detecting the position and a means for holding the sheet placement plate at a fixed position in accordance with the ascending operation of the detection member.

Further, in the present invention, a detection member for detecting the upper surface of the paper is arranged corresponding to the pickup roller of the paper feed member, and the vertical movement of the detection member causes the detection member to move up and down.
It is possible to adjust the position of the upper surface of the paper by providing a mechanism that releases and locks the member that holds and holds the paper placement plate. Further, in the present invention, means for controlling the ascending operation due to the rocking of the sheet placing plate is provided corresponding to the ascending position of the sheet, and the value of the normal force between the sheet and the pickup roller is set to a predetermined value. It is also possible to provide means for maintaining the range.

[0011]

In the sheet feeding device of the present invention constructed as described above, the end portion of the sheet placing plate for supporting the sheet inside the sheet feeding tray is swingably provided via the hinge, and the sheet placing plate is provided. A spring is arranged to raise the leading end of the sheet feeding side, and the sheet is pressed toward the pickup roller. Then, a paper height control member is arranged to detect the amount of the paper and raise the paper placement plate, and the detection member of the paper height control member that is in contact with the upper surface of the paper is rocked, so that the rocking arm The normal force between the sheet and the pickup roller can be maintained at a constant value by swinging the member to control the position where the sheet placing plate is locked.
Therefore, in the present invention, the normal force between the paper and the pickup roller is prevented from changing without being affected by the size of the paper, the amount of the paper, and the like, and the feeding action by the pickup roller is greatly changed. Therefore, it is possible to maintain good paper feeding performance.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A sheet feeding device of an image forming apparatus according to the present invention will be described with reference to the illustrated example. The example shown in FIGS. 1 and 2 shows the configuration of a sheet feeding device to which the present invention can be applied.
The paper feed tray 1 constitutes a paper storage unit surrounded by a frame as in the case of the conventional paper feed tray, and in the frame, the front plate 2 on the side for feeding the paper, the bottom plate 3, and the paper An end guide 4 and the like for restricting the rear end of the delivery side are arranged. Further, a pickup roller 6 for sending out a sheet, and a sheet separating device in which a sheet feed roller 7 and a retard roller 8 are combined are arranged on the sheet feeding member 5 arranged corresponding to the sheet feeding tray 1. Then, the pickup roller 6 of the paper feeding member 5 sends out the paper from the paper feed tray, and while separating the paper by the paper separating device,
A means for feeding the sheet toward the sheet conveying path in the downstream portion is configured.

In the paper feed tray 1, the spindle 1 is placed on the bottom plate.
The sheet placing plate 10 is arranged via the
In order to raise the leading edge of the paper feed side of 0, spring 1
2 are arranged. Then, the sheet mounting plate 10 is raised by the spring 12 so that the leading end of the sheet supported by the sheet mounting plate on the sheet feeding side is picked up by the pickup roller 6.
Then, the normal force having a predetermined value can be set between the paper and the pickup roller. Further, by detecting the position of the upper surface of the paper stored in the paper feed tray,
In order to regulate the rising position of the sheet placement plate, a sheet height control member 15 is arranged at a position close to the pickup roller. In the example shown in FIGS. The paper height detecting means is composed of the pressing roller 16a,
An example is shown in which a mechanism for activating the means for locking and holding the sheet placement plate is provided in accordance with the operation of the pressing roller moving up and down according to the height of the sheet.

The paper height control member 15 arranged in the paper feeding device can be constructed as shown in FIG. 3 and subsequent drawings. To simplify the explanation, the paper placing plate 10 and the paper height control member 15 are provided. Only the relationship between the height control member 15 and the configuration of the paper height control member 15 are shown. In the example shown in FIG.
The sheet height control member 15 is arranged on the sheet placing plate 10 which is biased in the upward direction by the spring 12, and the sheet height control member 15 is arranged so as to correspond to the upper surface of the sheet. The member 16 and the head-corresponding member 19 are arranged at both ends of an upper arm member 17 that is swingably provided via a support shaft 18, and the upper arm member 17 is configured to swing via the support shaft 18. are doing. A swing arm member 20 arranged corresponding to the head corresponding member 19 of the paper height control member 15 is swingably provided on a side portion of the paper stacking plate 10 via a support shaft 23. A rack 22 is formed on the sheet mounting plate side of the arm member 20.

Therefore, when the swing arm member 20 is swung counterclockwise via the support shaft 23, the rack 22 locks the side portion of the sheet stacking plate to prevent the sheet stacking plate 10 from rising. When the swing arm member 20 swings clockwise, the locked state of the sheet stacking plate 10 by the rack 22 is released and the sheet can be raised by a spring. That is, in the example shown in FIG. 3, the detection member 16 is supported by the fact that the paper is fed from the paper feed tray and the height of the paper is reduced on the paper placement plate 10 held at the fixed position. It is in a state of swinging counterclockwise via the shaft 18. Therefore, the head-corresponding member 19 that presses and holds the head portion 21 of the swing arm member 20,
Since the swing arm member 20 is swung in the clockwise direction via the support shaft 23, the rack 2 of the swing arm member 20 is operated.
The action of 2 holding and holding the side portion of the sheet placing plate 10 is released. When the locking by the swing arm member is released, the sheet placing plate 10 is lifted by the force of the spring 12.

As described above, when the sheet placing plate 10 is raised, the upper surface of the sheet is moved to the sheet height control member 15.
And the upper arm member 17 of the paper height control member 15 is rotated clockwise via the support shaft 18. Therefore, the head-corresponding member 19 provided at the tip of the upper arm member 18 acts to swing the head portion 21 of the swing arm member 20 toward the sheet placing plate 10, and the swing arm member 20. The rack 22 is rocked to a position where the side portion of the sheet stacking plate 10 is locked, and performs the action of locking the sheet stacking plate. Then, in a state in which the sheet placing plate 10 is locked and held by the swing arm member, the sheet placed on the sheet placing plate has a predetermined value with respect to the pickup roller of the sheet feeding member. It is maintained at a height where normal force can be exerted, and in that state, it is possible to continuously perform the operation of feeding several tens of sheets.

Further, in the example shown in FIG. 4, instead of directly locking the side portion of the sheet placing plate 10 to the rack of the swing arm member as shown in FIG. Board 1
The pinion member 26 is arranged on the side portion of 0 through the bracket 25, and the pinion member 26 is used as the rack 2 of the swing arm member.
It constitutes a means for locking to 2. The pinion member 26 is provided with a one-way clutch member 27 with respect to the support shaft. The one-way clutch member 27 does not allow rotation in the direction of raising the sheet loading plate, but the direction of lowering the sheet loading plate. To be able to rotate. Also,
A spring 24 is arranged behind the swing arm member 20 to urge the swing arm member 20 to swing counterclockwise through the support shaft 23 and swing with respect to the pinion member 26. By pressing the rack 22 of the arm member 20, it is provided so as to exert an action of retaining and holding the sheet placing plate 10.

Further, a paper height control member having the same structure as that of FIG. 3 is arranged on the paper placing plate of FIG. 4, and is swung by a head corresponding member of the paper height control member. A means for holding the head portion of the arm member is configured, and a state in which the detection member of the paper height control member is in contact with the upper surface of the paper supported by the paper placement plate is set. Therefore, the amount of the paper supported by the paper placing plate 10 is fed out, and the height of the paper is reduced, so that the upper arm member of the paper height control member is oscillated, so that the head portion of the oscillating arm member is oscillated. When the action of urging the counterclockwise direction via the support shaft 23 is interrupted, the locking action of the rack 22 with respect to the pinion member 26 is released, and the sheet stacking plate 10 is released.
Has a function to raise the sheet to a predetermined height by sliding up the teeth of the pinion member 26.

Further, when the sheet placing plate 10 is lifted by the force of the spring 12 and reaches a predetermined height, the upper arm member of the sheet height control member is swung via the support shaft to swing. Since the arm member 20 is swung in the direction of coming into contact with the sheet stacking plate via the support shaft 23, the pinion member 26
Can be locked by the rack to perform a retained action. When there is no sheet on the sheet placing plate 10, a no-paper sensor arranged corresponding to the sheet placing plate 10 outputs a signal indicating that there is no sheet, and the control panel of the image forming apparatus is instructed to replenish the sheet. Is displayed. When the operator replenishes the paper, the paper placing plate 1
By pressing 0 by hand, the one-way clutch member 27 allows the pinion member 26 to rotate and lowers the sheet loading plate along the rack. At the position where the sheet loading plate is lowered, the swing arm member 20 The rack 22 of FIG.

As described above, in addition to the function of fixing and holding the sheet placing plate by the swing arm member,
In the present invention, in order to regulate the height of the paper in the paper feed tray, as shown in FIG.
It is also possible to dispose the pinion member 30 with respect to 1 and to provide a means for locking the pinion member 30 with a stopper member 31 that interlocks with the sheet height control member. FIG. 5
In the example shown in FIG. 5, the upper arm member 17 of the paper height control member 15 is swingably provided via the support shaft 18, and the pressing roller 16 is provided at one end of the upper arm member 17.
Arranging a to configure the means for detecting the height of the sheet is the same as in the case of FIG. Further, a stopper member 31 is arranged at the other end of the upper arm member 17 of the paper height control member 15, and a pinion member 30 is arranged on a support shaft 11 for swinging the paper stacking plate 10. On the other hand, it constitutes a means for locking the stopper member 31.

In the example shown in FIG. 5, when the height of the sheet is reduced while the sheet placing plate 10 is fixed, the pressing roller 1
By the lowering of 6a, the stopper member 31 releases the engagement with the pinion member 30, and the force of the spring 12 raises the sheet placing plate 10. Then, when the sheet rises to a predetermined height and pushes up the pressing roller 16a, the stopper member 31 locks the pinion member 30, so that the sheet placing plate is stopped from rising and the sheet is conveyed to the pickup roller 6. Hold it in a position where it can exert a predetermined normal force. In this state, if the height of the paper is reduced while the pickup roller 6 is being driven to feed the paper, the paper height control member 15 further raises the paper placement plate to pick up the paper. The operation of holding the sheet in the pressing position is repeatedly performed so that the operation of feeding the sheet from the sheet feeding tray can be continued. In the example shown in FIG. 5, the means for locking and holding provided on the swing support shaft 11 of the sheet stacking plate 10 is not limited to using a pinion member as shown in the embodiment, but is arbitrary. It is also possible to provide the brake means having the above-mentioned configuration, and in association with the brake means, it is possible to configure a mechanism for operating the brake means in the paper height control member.

In addition to the above-described embodiment, in the present invention, as shown in FIGS. 6 and 7, the action of vertical movement is controlled with the sheet placing plate fixed to the belt member. Alternatively, a mechanism for controlling the vertical movement can be configured by using a rack provided on the sheet placing plate. In the example shown in FIG. 6, the belt member 40 is arranged on the side portion of the sheet placing plate 10, and one end of the sheet placing plate is attached to the belt member via the fixing portion 43, so that the sheet placing plate is And a means for moving the belt member 40 following the vertical movement of the belt member. Further, the pulley 4 that supports the belt member 40.
1, 42 are configured to allow free rotation, but the paper height control member 15 is made to correspond to the upper pulley 41.
A stopper member 44 is arranged at one end of the upper arm member 17 of FIG.

The pressure roller 16a of the paper height control member 15 moves up and down according to the height of the paper,
By pressing the stopper member 44 against the belt member 40, the paper placing plate 10 can be raised by the force of the spring 12 and the height of the paper can be kept constant. Further, in a state where the pressing force of the sheet supported by the sheet placing plate 10 against the pickup roller is small, the pressing roller 16a descends, so that the pressing of the belt member 40 by the stopper member 44 is released and the sheet placing plate is released. Control is performed such that 10 is raised by the force of the spring 12 to raise the pickup roller to a position where a predetermined normal force can be exerted. As the belt member, a rubber belt, a plastic belt-shaped member, a wire, or the like can be used, and by arranging a stopper member in accordance with the characteristics of these belt-shaped members, The function of pressing the belt member toward the upper pulley and holding it can be exhibited. Further, the stopper member can be provided not only as a means for pressing and fixing the belt member against the pulley but also as a means for fixing the pulley. Also, it is possible to perform the same operation.

In the example shown in FIG. 7, an arm member 50 is arranged upright on the side of the sheet stacking plate 10 and a rack member 51 of the arm member 50 is provided with a stopper member 52 of a sheet height control member. A means for locking is provided. Also,
In the paper height control member 15 arranged with respect to the arm member 50, a stopper member 52 is arranged at one end of the upper arm member 17, and the upper arm member 1 swings via a support shaft.
A pressure roller 16a is arranged at the other end of the sheet 7 to form a means for detecting the height of the sheet. Then, the sheet placing plate 10
Depending on the height of the paper P supported by the upper arm member 1,
7 is rocked so that the stopper member 52 is locked to the rack 51 and the locked state is released.
Therefore, even when the paper height control member as shown in FIG. 7 is arranged, it is possible to set a normal force of a predetermined value between the pickup roller of the paper feed member and the paper. In the paper height control member of the present invention as described above, when the stopper member or the like is locked to the rack and the pressing force of the stopper member is insufficient in order to regulate the rise of the paper loading plate, By providing additional urging means such as urging means such as a spring with respect to the upper arm member, the operation of the paper height control member can be reliably performed.

[0025]

Since the sheet feeding device of the image forming apparatus of the present invention has the above-described structure, the end of the sheet placing plate for supporting the sheet inside the sheet feeding tray is provided with a hinge. And a spring to raise the leading edge of the paper loading plate on the paper feed side, and to press the paper toward the pickup roller and place it on the paper loading plate. It is possible to set a normal force of a predetermined value for the sheet to be picked up with respect to the pickup roller of the sheet feeding member. Then, a paper height control member is arranged to detect the amount of the paper and raise the paper placement plate, and the detection member of the paper height control member that is in contact with the upper surface of the paper is rocked, so that the rocking arm Since the position at which the sheet placing plate is locked by swinging the member is controlled, it is possible to maintain good sheet feeding performance. Therefore, in the present invention, the normal force between the paper and the pickup roller is prevented from changing without being affected by the size of the paper or the amount of the paper, and the feeding action by the pickup roller is greatly changed. Will disappear. Further, according to the present invention, the pressing means by the spring is arranged and the paper height control member is arranged with respect to the paper placing plate on which the paper is placed inside the paper feeding tray. Can be controlled, so that the structure of the paper feed tray and the structure of the raising means of the paper placement plate can be simplified, and can be easily installed in the paper feed unit of any image forming apparatus. .

[Brief description of drawings]

FIG. 1 is a side view showing a configuration of a paper feed tray of the present invention.

FIG. 2 is an explanatory diagram showing an arrangement relationship of a paper height control member with respect to a paper feed tray.

FIG. 3 is an explanatory diagram of a first embodiment of the paper height control member of the present invention.

FIG. 4 is an explanatory diagram of a second embodiment of the paper height control member of the present invention.

FIG. 5 is an explanatory diagram of a third embodiment of the paper height control member of the present invention.

FIG. 6 is an explanatory view of a fourth embodiment of the paper height control member of the present invention.

FIG. 7 is an explanatory diagram of a fifth embodiment of the paper height control member of the present invention.

[Explanation of symbols]

1 paper feed tray, 5 paper feed member, 6 pickup roller, 10 paper placing plate, 11 support shaft,
12 springs, 15 paper height control member,
16 detection member, 17 upper arm member, 19
Head corresponding member, 20 Swing arm member, 21
Head, 22 racks, 25 brackets,
26 pinion member, 27 one-way clutch member, 30 pinion member, 31 stopper member, 40 belt member, 50 arm member, 5
1 rack, 52 stopper members.

Claims (1)

[Claims] 1. A means for arranging a sheet feeding member corresponding to a sheet feeding portion of a sheet feeding tray, and providing means for feeding the sheets accommodated in the sheet feeding tray one by one by the sheet feeding member. A sheet placing plate on which a sheet is placed and an urging means for raising a sheet feeding side end of the sheet placing plate are provided, and an upper surface of the sheet placed on the sheet placing plate and a pickup of a sheet feeding member. In a paper feeding device comprising means for pressing a predetermined force between rollers, a paper height control for adjusting a rising position with respect to a paper placing plate supporting a paper inside the paper feeding tray A member is disposed, and the paper height control member is configured by a detection member that detects a rising position of the paper, and a unit that holds the paper placement plate at a fixed position according to the rising operation of the detection member. A sheet feeding device of the image forming apparatus.