JP2001114424A - Paper feeder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a paper feeder capable of keeping feeding pressure in a proper range without being affected by the stacked condition of paper and the weight of paper. SOLUTION: This paper feeder comprises a cassette case 1 on which paper is stacked, a elevating means for elevating the stacked sheets on a bottom plate 2, a detecting means 14 for detecting the uppermost position of the sheet surface of the stacked sheets in front of and near a feeding roller 10, a control means for setting feeding pressure as predetermined with the drive of a motor 7 in accordance with a control signal from the detecting means 14, an elastic part 15 associated with the elevating operation and a rotor 16 adapted to contact the elastic part 15 while selecting its resilience.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper feeder provided in a copying machine, a printer, a facsimile, and the like.

[0002]

2. Description of the Related Art In a copier or the like, it is necessary to stably obtain a paper feeding pressure (a pressing force applied between a top end of a stacked paper surface and a paper feeding roller) in order to maintain paper feeding performance. Is important. This paper feed pressure is directly affected by the weight difference depending on the size of the paper, whereas in the past, the paper feed pressure averaged over all sizes was set. This type of sheet feeding device is shown in FIGS.

A cassette case 1 has a bottom plate 2 on which sheets are stacked, and the bottom plate 2 is rotatable about an A-axis. On the back side of the bottom plate 2, there is provided an elevating shaft 3 to which an elevating arm 4 corresponding to the back side is fixed. Further, as shown in FIG. 7, the paper P stacked on the bottom plate 2 in the cassette case 1 is
The position of a sheet (hereinafter, also referred to as a stacking sheet) corresponding to the size is correctly regulated by the left and right side fences 5 and the end fence 6 not shown in FIG. The side fence 5 and the end fence 6 are adjusted to positions near the sides of the bottom plate 2 that can move up and down, and regulate the side surface of the stacked paper P.

[0006] In FIG. 6, means for lifting and lowering the stacked paper P is
The motor 7, the coil spring 8, the coupling 9, the elevating shaft 3, the bottom plate 2, and the like are configured. One end of the elevating shaft 3 in which the elevating arm 4 is in contact with the back side of the bottom plate 2 is connected to the main body of the copier by a pin 11 via a coupling 9. A motor 7 is provided on the main body of the copying machine, and a first lever 12 attached to the drive shaft pulls one end of a coil spring 8 at its tip, and the other end of the coil spring 8 drives one end of the elevating shaft 3. The second lever 13 to be hooked is rotated. The rotation of the second lever 13 rotates the elevating shaft 3 connected by the coupling 9 and drives the elevating arm 4 in a direction to raise it. In this way, the first half of the stacked paper P placed on the bottom plate 2 is lifted,
The leading end of the uppermost paper surface is pressed against the paper feed roller 10, and the paper feed pressure is continuously applied as much as the coil spring 8 extends.

In the above-described paper feeder, the amount of rotation of the motor 7 is controlled to a constant value by the detection portion 12a of the first lever 12 driven by the motor 7 reaching the stop sensor 17. The amount of extension of the coil spring 8 resulting from the constant amount of rotation of the first lever 12 is supplied to the feed roller 10 by the elastic energy remaining after subtracting the amount extended by the weight or mechanical resistance of the stacked sheets P. This will create paper pressure. The size switching dial 18 is for recognizing the paper size of the stacked paper P with a size detection sensor (not shown) and controlling the transport timing and the image forming area.

[0008] FIG. 8 is a diagram showing the conventional paper feeding apparatus.
The relationship between the number of stacked sheets and the paper feed pressure is shown by taking the length and A3 length as examples. Here, the own weight of the loaded paper P acts in a direction to cancel the paper feed pressure, and the weight of the paper increases with the paper size, that is, the volume of the loaded paper P. As shown by the solid line in FIG. 8, even if the same 500 sheets are used, the sheet feeding pressure of the A3 length is lower than that of the A4 length due to the difference in weight. The effect of this size difference is eliminated as the number of sheets stacked decreases due to paper feeding, and both paper feeding pressures eventually converge to a predetermined value. Such a variation in the paper feed pressure between the sizes is averaged by setting a value at which each paper feed pressure converges to zero sheets to a substantially intermediate value in the appropriate area.

[0007]

However, in the above-mentioned conventional paper feeding apparatus, an appropriate paper feeding pressure cannot be obtained depending on how the user sets the loaded paper P, causing troubles such as multi-sheet feeding and non-feeding. As a countermeasure, it is necessary to limit the size.

For example, if the side fence 5 and the end fence 6 are tightly set, or irregular paper is forcibly pushed between the fences, the gap between the fixed fences 5 and 6 and the rising edge of the stacked paper P is increased. Contact resistance occurs. This becomes a drag against the sheet feeding pressure, and the sheet feeding pressure is reduced as a whole as shown by a chain line in FIG. This effect increases as the number of stacked sheets increases, so that if the paper feed pressure is significantly reduced, the initial value of the paper feed pressure in the A3 length is deviated to the lower side of the appropriate area, and non-feeding occurs.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and is intended to maintain a sheet supply pressure within an appropriate range without being affected by a sheet stacking state, a difference in sheet size, and the like. It is intended to provide a paper device.

[0010]

In order to achieve the above object, a sheet feeding apparatus according to the present invention comprises a cassette case on which sheets are stacked and a sheet loaded on the cassette case. Elevating means for maintaining the state of being urged against the paper rollers, detecting means for detecting the uppermost paper surface position of the stacked paper, based on a control signal of the detecting means and the distance between the uppermost paper surface and the paper feed roller Control means for driving the elevating means to apply a predetermined paper feeding pressure between the stacked papers and the paper feeding rollers.

Further, a plurality of stoppers which contact the elastic portion which moves in conjunction with the elevating operation of the elevating means and the elastic portion which moves with a decrease in the stacking amount of sheets and which can select the amount of bending of the elastic portion. And a part.

Further, the elastic portion is an elastic plate which is rotated at the base end thereof by the elevating means, and the plurality of stoppers are provided on one of the rotation trajectories of the distal end of the elastic plate. It can be configured as a cam-shaped rotating body where the contact surface is located.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view illustrating the configuration of the sheet feeding device according to the present embodiment. In the figure, cassette case 1 is 2
This is indicated by a dashed line, and illustration of the paper is omitted. In the configuration of the present paper feeding apparatus, the same components as those of the conventional example are denoted by the same reference numerals, and detailed description will be omitted.

The loading paper lifting means comprises a motor 7, levers 12, 13, a coil spring 8 hooked between the levers, a coupling 9, a lifting shaft 3, a lifting arm 4, and the like. The elevating means is substantially the same as the conventional example, but the control means of the motor 7 is different.

The control means of this embodiment comprises the elevating means and the loading height detection sensor 14 for detecting sheets, and the timing of stopping the motor 7 is controlled by the loading height detection sensor 14. As a result, a constant paper feed pressure is set regardless of the paper size or the like. This control will be described with reference to FIG.

FIG. 2 is a side view showing the vicinity of the leading end portion of the stacked paper P provided with the above-described stacked height detection sensor 14. As shown in FIG. 1A, when the stacking paper P is placed on the bottom plate 2 and mounted in a copying machine (not shown), the leading end of the stacking paper P is located below the stacking height detection sensor 14. The loading height detection sensor 14 has a sensor portion 14a disposed at a position slightly lower than the paper feed roller 10, and as shown in FIG.
When the stacked paper P is lifted by the elevating means, the top end of the paper surface comes into contact with the sensor portion 14a and is detected by the stacked height detection sensor 14. Here, a predetermined distance h is set between the uppermost sheet surface position detected by the sensor unit 14a and the paper feed roller 10. In the present embodiment, the predetermined distance h is set to 5 mm, but this value may be appropriately set according to the required control accuracy or the like.

After the driving of the motor 7 is started, when the loaded height sensor 14 detects the loaded paper P, the loaded paper P is further moved according to a predetermined distance h to the paper feed roller 10, and the pressure is applied to the paper feed roller 10. The motor 7 is driven by the necessary amount of rotation. That is, the relative height of the loaded paper P with respect to the paper feed roller 10 is detected by the loaded height detection sensor 14 arranged near the paper feed roller 10, and the motor 7 is controlled to stop at a certain timing based on this detection. I do. As a result, the rotation amount of the motor 7 until the uppermost sheet reaches the stacking height detection sensor 14 depends on the contact resistance between the stacking sheet P and the fence or the like and the weight difference between the sizes. Pressure can be obtained.

Further, the paper feeder of this embodiment is provided with a correction mechanism capable of correcting a change in paper feed pressure due to a decrease in the weight of the stacked paper P due to paper feed. This correction mechanism is to prevent the sheet feeding pressure from exceeding an appropriate range according to the sheet size, and includes a plate-shaped elastic portion 15 fixed to one end of the elevating shaft 3;
It is constituted by a size switching dial comprising a rotating body 16 capable of adjusting a contact position with the elastic portion 15. That is, if the control means forms a constant paper feed pressure irrespective of the paper weight difference between the sizes, for example, the tension of the coil spring 8 increases when the weight is high,
The tendency of increasing the sheet feeding pressure with the decrease in the number of sheets increases. The correction mechanism of the present example is a mechanism that suppresses such an upward tendency as necessary. This correction mechanism will be described with reference to FIGS.

FIG. 3 shows a side view of the correction mechanism, and FIG. 4 shows an operation state thereof. In these figures, the elastic part 1
The base end portion 15a of 5 is fixed to an elevating shaft 3 for elevating and lowering the bottom plate 2, and rotates counterclockwise in conjunction with the elevating operation. The rotating body 16 has a cam shape in which a plurality of contact surfaces 16a and 16b are formed as a plurality of stopper portions, and is rotatably supported on a side surface portion of the cassette case 1. The plurality of contact surfaces in this embodiment include a contact surface 16a having a large radius d corresponding to A3 length and a contact surface 16b having a small radius d 'corresponding to A4 length.

As shown in FIG. 3, the stacked paper P on the bottom plate 2
Is present in a large amount, the elastic portion 15 is separated from the rotating body 16, but the distance is reduced as the bottom plate 2 rises as the sheet feeding proceeds. The rotation angle of the rotating body 16 can be set by the user's hand, and it is arbitrary which contact surface is arranged on the rising trajectory of the distal end portion 15b. The location where the tip 15b of the elastic portion 15 is caught is defined according to the size of each sheet by the radius (for example, d or d ') of the contact surface selected here.

As shown in FIG. 4A, when a sheet of A3 length is fed, the rotating body 16 is brought into contact with the contact surface 16a of the A3 length.
, The distance between the contact surface 16a and the elastic portion 15 is reduced. When the A3 length is fed and becomes smaller than the predetermined number T, the distal end portion 15b of the elastic portion 15 comes into contact with the contact surface 16a. From here on, as shown by the two-dot chain line in the figure, the elastic portion 15 bends upward to generate a repulsive force against the upward force of the bottom plate 2. Due to the elastic force of the elastic portion 15, a force for suppressing an increase in the sheet feeding pressure acts after the contact.

On the other hand, as shown in FIG. 4B, when feeding A4 length paper, the rotating body 16 is brought into contact with the contact surface 16 of the A4 length paper.
b is turned down. The contact surface 16b has a small radius, so that even if all the sheets P are fed, the contact surface 16b does not contact the elastic portion 15. If the distance between the elastic portion 15 and the elastic portion 15 is increased, the elastic portion 15 does not bend to the end, and no repulsive force for canceling the sheet feeding pressure is generated. FIG. 5 shows the paper feed pressure fluctuation of the A4 length and the A3 length.

FIG. 5 shows the number of stacked sheets on the horizontal axis,
FIG. 3 is a diagram illustrating a paper feed pressure variation in the vertical and A4 lengths. As shown in FIG. 3, the stop pressure of the motor 7 via the above-described load height detection sensor 14 causes the initially set sheet pressure,
That is, the sheet feeding pressure at the time of 500 sheets is the same between different sizes of A3 length and A4 length. As shown by the chain line in the drawing, when the elastic energy stored in the coil spring 8 is large due to the contact resistance with the side fence or the like, the paper feed pressure increases as the number of sheets decreases. This increase is remarkable as the number of stacked sheets decreases.

In the case of A3 length, since the weight is higher than that of A4, the elastic energy stored in the coil spring 8 becomes relatively large by that amount. There is a tendency to rise. In this case, if there is any load resistance or the like, there is a danger of exceeding the appropriate area because it is deviated in the chain line direction. Therefore, when the A3 length is reduced to T sheets, the elastic portion 15
Is provided with a correction mechanism so that abuts against the rotating body 16.
As a result, the increase of the sheet feeding pressure for T sheets or less is suppressed, and conversely, the sheet feeding pressure decreases. In this way, the sheet feeding pressure, which tends to increase, is canceled by the elastic portion 15 when the number of remaining sheets is small, so that the sheet feeding pressure is corrected so as to fluctuate within an appropriate region.

The correction operation of the sheet feeding pressure in the present embodiment has been described by taking the A3 length as an example. However, this is merely an example, and whether or not correction is actually required and how much correction is required are described. Whether or not to make the setting depends on various parameters such as the number of sheets that can be stacked and the rotation amount of the motor 7 (the elastic force of the coil spring 8 stored for achieving a desired sheet feeding pressure). Therefore, this does not indicate that A3 length requires correction or that A4 length requires no correction. Further, in the present embodiment, a leaf spring is used for the elastic portion 15 and the coil spring 8 is used for the pressurizing mechanism of the elevating means. However, the present invention is not limited to such a configuration, and other flexible members can be used. .

[0026]

As described above, the paper feeding device of the present invention raises the cassette case on which the paper is loaded and the paper loaded in the cassette case and urges the paper feeding roller. Elevating means for maintaining the loaded state, a detecting means for detecting the position of the uppermost sheet surface of the stacked sheets, and driving the elevating means based on a control signal of the detecting means and a distance between the uppermost sheet surface and the sheet feeding roller. And a control means for applying a predetermined paper feed pressure between the loaded paper and the paper feed roller, so that the actual paper height is detected and the paper feed pressure is controlled to set the paper. Regardless of the state and the sheet size, an appropriate sheet feeding pressure with little variation can be obtained.

Further, a plurality of stoppers which contact the elastic portion which moves in conjunction with the elevating operation of the elevating means and the elastic portion which moves as the stacking amount of the paper decreases and which can select the amount of bending of the elastic portion. According to this configuration, an appropriate sheet feeding pressure can be obtained while suppressing an increase in the sheet feeding pressure caused by the influence of a size difference or the like.

[Brief description of the drawings]

FIG. 1 is a perspective view illustrating a configuration of a sheet feeding device according to an embodiment.

FIGS. 2A and 2B are main part side views illustrating a sheet feeding pressure setting according to the present exemplary embodiment. FIG. 2A is a diagram illustrating a state immediately after the sheet feeding device is mounted, and FIG.

FIG. 3 is a side view of a sheet feeding device including an elastic portion and a rotating body.

FIG. 4 is a side view for explaining the operation of the elastic portion of the embodiment.
(A) is a diagram showing the case of A3 length, and (b) is a diagram showing the case of A4 length.

FIG. 5 is a diagram showing a paper feed pressure variation in the paper feed device of the present embodiment.

FIG. 6 is a perspective view illustrating a configuration of a conventional sheet feeding device.

FIG. 7 is a perspective view illustrating a state where sheets are stacked in a sheet feeding device.

FIG. 8 is a diagram showing a paper feed pressure variation in a conventional paper feed device.

[Explanation of symbols]

 Reference Signs List 1 cassette case P stacked paper 10 paper feed roller 14 detecting means (load height detection sensor) 15 elastic part 15a base end of elastic part 15b distal end of elastic part 16 rotating bodies 16a, 16b plural stopper parts

Claims (3)

[Claims] 1. A cassette case on which sheets are stacked, lifting means for lifting the sheets stacked in the cassette case and keeping the sheets urged against a paper feed roller, and Detecting means for detecting the position of the upper surface of the sheet, and driving the elevating means on the basis of the control signal of the detecting means and the distance between the uppermost sheet and the sheet feed roller, thereby providing a predetermined distance between the stacked sheets and the sheet feed roller. And a control unit for applying the sheet feeding pressure of the sheet feeding device. 2. A plurality of stoppers which contact the elastic portion which moves in conjunction with the elevating operation of the elevating means and the elastic portion which moves as the stacking amount of the paper decreases and which can select the amount of bending of the elastic portion. The sheet feeding device according to claim 1, further comprising: a unit. 3. The elastic portion is an elastic plate which is rotated by a base end thereof being driven by the lifting / lowering means, and wherein the plurality of stoppers are provided on one rotation trajectory of the distal end of the elastic plate. 3. The sheet feeding device according to claim 2, wherein the sheet feeding device is formed of a cam-shaped rotating body on which the contact surface is located.