JP2002167058A - Paper feeding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a paper feeding device capable of preventing the occurrence of improper paper feeding by corresponding to various types of papers having different density (weight) and performing the optimum paper feeding pressure control by changing a paper feeding pressure from a paper feeding roller by corresponding to a difference in density of paper to be fed and capable of easily switching settings by providing a setting switching means for types of papers in a paper feeding tray. SOLUTION: This paper feeding device is provided with the paper feeding tray 1, the paper feeding roller 6 coming into pressure-contact with an uppermost face of a transfer paper P loaded in the paper feeding tray to feed transfer papers on the uppermost face one by one, a paper raising mechanism raising a bottom plate in the paper feeding tray to bring the transfer paper on the uppermost face into pressure-contact with the paper feeding roller, a control part controlling the operation of the paper raising mechanism, and a paper type setting switching means 112 setting type of paper loaded on the paper feeding tray. The paper raising mechanism is provided with a paper raising motor 21, a lever 23 turning and moving vertically by the paper raising motor, and an ascent detection sensor 25 detecting a position of the lever. The control part controls the paper raising motor based on the information on type of paper set by the paper type setting switching means.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copying machine, a printer,
Regarding the improvement of the paper feeder used for image forming devices such as facsimile machines, more specifically, paper is fed by adjusting the paper feed pressure to an appropriate value according to the paper type of the paper to be fed, especially the difference in paper density. The present invention relates to a sheet feeding device that significantly reduces the rate of occurrence of defects.

[0002]

2. Description of the Related Art In electrophotographic image forming apparatuses such as copiers, printers, and facsimile apparatuses, and other image forming apparatuses employing a recording method, an image forming section includes a sheet feeding device provided inside and outside the image forming apparatus main body. The image is formed on the paper by feeding paper (transfer paper, recording paper) one by one toward the paper. FIGS. 7A, 7B, and 7C show a plan view, a front view, and a bottom plate pushing-up mechanism on a sheet feeding tray side showing a configuration of a sheet raising mechanism used in a conventional sheet feeding device (unknown). FIG. This paper feeder relates to a front loading type paper feeder having a configuration in which a paper feed tray is attached and detached in a direction orthogonal to the paper feed direction. The paper raising mechanism mainly includes paper raising motor units 21 to 26, lifting units 11 to 13, and tension springs 32 and 33 connecting these units. The paper-lifting motor 21 in the paper-lifting motor unit has a meshing portion 21a at the tip of its drive shaft,
Meshing portion 22a provided at one end of movable shaft 22 disposed opposite
It is a configuration to fit. The movable shaft 22 is movable in the thrust direction in conjunction with the attachment / detachment of the paper feed tray 1, and moves to the paper-lifting motor 2 side when the tray is set to set the paper feed tray in the setting direction indicated by the arrow. 21 are separated from each other by the return force of the compression spring 26 when not set. The shaft 22 has a lever 23
Is fixed, and transmits the driving torque of the paper raising motor 21 to the lever 23 when the paper feed tray 1 is set. Further, in order to stop the rotation of the lever 23 at a predetermined position, the position of the lever 23 is notified to the control unit.
A photo interrupter 25 interrupted by 3 is arranged.

The lifting unit includes a coupling 11 that meshes with a projection provided at the tip of a bottom plate raising shaft 3 in the paper feed tray 1.
And a shaft 12 connected to the coupling 11 and a lever 13 fixed to the shaft 12. When sheets are stacked on the bottom plate 5 of the paper feed tray 1 and set in an apparatus main body (not shown), the side wall of the paper feed tray pushes the end of the shaft 22,
The shaft 22 and the drive shaft of the paper-lifting motor 21 are connected. At this time, the paper lifting motor 21 starts to be driven by a detection signal from a paper feed tray set detection sensor (also used as a paper size detection sensor; not shown), and the lever 23 rotates counterclockwise in FIG. 7B. The other lever 13 interlocks with the movement of the lever 23 via a tension spring 32, and drives the shaft 3 for raising the bottom plate of the sheet feeding tray. Axis 3 is bottom plate rising arm 4
The arm 4 pushes up the bottom plate 5 and presses the sheet P on the bottom plate 5 against the paper feed roller 6. By stopping the paper raising motor 21 when the lever 23 interrupts the photo-interrupter 25, the lifting of the bottom plate 5 is stopped, and the paper feed roller 6 is fed by a predetermined spring from tension springs (pressure springs) 32 and 33. Pressure is applied. In the state where the driving of the paper raising motor 21 is stopped, the shaft 12 and the shaft 3 are fixed at the angle, so that the lever 4 maintains the angle when the motor stops. Therefore, after the motor 21 stops, the bottom plate 5 is pushed up by the force in the pushing direction from the tension spring 32. Further, in this conventional example, a size dial (not shown) for setting the paper size is provided on the paper feed tray 1, and the paper is detected by a detection device (not shown) provided on the main body side when the paper feed tray is set. Further, the lever 13 is formed with an uneven shape, and the remaining amount of the paper is detected in several stages by a combination of signals depending on whether or not each of the plurality of photo interrupters is interrupted. The position of the lever 13 is changed according to the paper size by the combination of the paper size and the paper remaining amount.
The control is performed to return the shutter to the shut-off position for a predetermined time depending on the remaining amount of paper, and the like. According to this conventional example, the setting force of the paper feed tray can be reduced by using a motor as means for raising the paper and the bottom plate and applying the paper feed pressure. In addition, the conventional auxiliary transmission mechanism is eliminated, and the motor is rotated forward or backward from the normal stop position for a predetermined time by the detection signal of the paper size and the remaining amount of paper. A configuration is provided in which a difference in pressure is corrected to prevent non-feeding of a sheet and feeding of a large number of sheets, thereby obtaining a good sheet feeding performance. As a result, it is possible to provide a sheet feeding device that can simplify the device configuration and that can improve reliability and reduce costs.

In general, the density of plain paper is 0.7 to 0.7.
0.8 occupies the majority, while the density of coated paper (coated paper, art paper, etc.) having a surface coated is often 0.9 to 1.2. In the conventional paper feeder described above, if the density of the paper has a difference greater than a predetermined value, the weight of the paper will differ even at the same stacking height, and this will cause a difference in the feed pressure applied to the feed roller. As a result, the paper feeding pressure may be out of the proper range. This problem is more remarkable as the amount of paper loaded on the bottom plate increases, and conversely, there is no difference at the time of paper end.

FIGS. 8A and 8B show the relationship between the torque generated by the tension force of the tension spring 32 acting on the shaft 3 and the amount of paper P loaded on the bottom plate 5 in this conventional apparatus. FIG. 5 is a diagram illustrating a state where the required paper feed pressure (the pressure at which the upper surface of the paper on the bottom plate contacts the paper feed roller 6) changes. First, as shown in FIG. 8A, in the conventional apparatus, the spring force of the tension spring 32 is set in accordance with the plain paper. In the case of paper, the tension spring 32 shrinks in proportion to the decrease in the load weight, so the shaft 3
And the torque acting on it decreases. For this reason, the paper feed pressure between the paper feed roller 6 and the upper surface of the paper can maintain a constant value for plain paper as shown in FIG. However, a tension spring 32 whose spring force is adjusted to that of plain paper is used.
When a high-density paper having a heavy weight per unit thickness (or the number of sheets) is loaded by a paper raising mechanism unit using, the required torque is larger than that of plain paper as shown in (a). However, in practice, the pressure is continuously increased by the same torque as that of plain paper. Therefore,
As shown in (b), when stacking and feeding high-density paper, the spring force of the spring 32 is based on plain paper, so the paper feed pressure at full loading is inadequate. As the paper advances and the loaded weight decreases, the inconvenience occurs that the paper feed pressure increases and approaches an appropriate range. When the pressure of the tension spring 32 is set on the basis of the plain paper in this manner, the feeding pressure becomes insufficient for the high-density paper, causing many non-feeds. When the pressing force of the spring 32 is set, the paper feed pressure becomes excessive for plain paper, and frequent feeding occurs. In any case, paper feed failure such as double feed or non-feed is likely to occur,
There was a problem that the paper feeding performance could not be satisfied.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and provides an optimum paper feed pressure control by changing a paper feed pressure in accordance with a difference in density of paper to be fed. The object of the present invention is to provide a paper feeder capable of preventing the occurrence of a paper feed failure in response to various types of paper having different paper densities. It is another object of the present invention to provide a paper feeder that can easily switch settings by providing a paper type setting switching unit in a paper feed tray.

[0007]

In order to solve the above-mentioned problems, the invention of claim 1 supports the transfer paper loaded on the bottom plate supported so as to be able to be pulled up and down in a direction orthogonal to the paper feeding direction. Paper feed tray, a paper feed roller that presses against the uppermost surface of the transfer paper stacked in the paper feed tray and feeds the uppermost transfer paper one sheet at a time, A paper raising mechanism for pushing up the bottom plate in the tray to press the uppermost transfer paper against the paper feed roller, a control unit for controlling the operation of the paper raising mechanism, and a paper type stacked on the paper feed tray. A paper type setting switching means for setting, the paper raising mechanism includes a paper raising motor that outputs a driving force for pushing up the bottom plate, a lever that is vertically rotated by the paper raising motor, and a position of the lever. A rise detection sensor for detecting
An arm that is actuated by the driving force from the paper lifting motor to push up the bottom plate, and wherein the control unit controls the paper lifting motor based on information about the paper type set by the paper type setting switching unit. It is characterized by controlling. The invention according to claim 2 is characterized in that the paper type setting switching means is a switching lever or a sensor provided on the paper feed tray.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on an embodiment shown in the drawings. FIG. 1 is an overall schematic diagram showing an example of an electrophotographic image forming apparatus equipped with a sheet feeding device of the present invention, FIG. 2 is a main part configuration diagram thereof, and FIG. 3 is an exploded perspective view showing a configuration of a paper raising mechanism. is there. This image forming apparatus includes:
The apparatus includes a document feeding unit A such as an automatic document feeding device, a reading optical system B for reading a document image, an image forming unit C, and a sheet feeding unit (sheet feeding device) D. 7, the same parts as those shown in FIG. 7 will be described by giving the same reference numerals. In the present invention, since only the sheet feeding unit, that is, the sheet feeding device D is involved, description of other components is omitted. Further, the sheet feeding device of the present invention is not limited to being applied only to an apparatus having an electrophotographic image forming section as shown in the drawings, and is generally applied to an image forming apparatus having an image forming section having various recording methods. Applicable. This paper feeder D
Is provided with a plurality of paper feed trays 1, and the paper P stacked on the bottom plate 5 of each paper feed tray 1 is taken out one by one by a paper feed roller 6 in contact with the uppermost surface thereof, and Is conveyed to the image forming section C through the path indicated by the arrow. On the other hand, each paper feed tray 1 is configured to be detachable in a drawer shape from an installation port 100 provided on the front surface of the main body of the image forming apparatus toward the inner part. The paper feed tray 1 supports a bottom plate 5 as shown in FIG. 7C so as to be able to move up and down in a casing 101 constituting an outer wall, while raising the bottom plate driven by a lifting motor (paper raising motor) 21. Axis 3 of
And a bottom plate raising arm 4 integrated with the shaft 3. The tension spring (pressure spring) 32 has its spring force set according to the weight of the high-density paper.

In FIGS. 7 and 3, when the paper feed tray 1 is set in the mounting opening 100 of the apparatus main body, the setting is detected by a set detection sensor (not shown), and the paper raising motor 21 is started. The lever 23 rotates clockwise in the figure, and a part of the lever 23 is a rising detection sensor (photo interrupter).
When the number reaches 25, the control unit 110 stops the raising motor (paper raising motor) 21. In the present invention, the control unit (CP
U, ROM, RAM, etc.) 110 by the ascending motor 21 depending on whether the plain paper is selected or the high-density paper is selected based on the control information stored in the storage unit. Is configured to vary the paper feed pressure applied to the sheet. In any case, the control unit 110 is informed in advance of the type of paper, that is, whether it is plain paper or heavy-weight high-density paper. The means for selecting the paper type will be described later.

FIG. 4 is a view for explaining the rotation angle of the lever 23. First, when "plain paper" is selected,
In order to raise the lever 23 at the initial position to an angle suitable for feeding plain paper (the height position of the bottom plate 5), the lifting motor 21 is rotated forward and a part of the lever 23 is moved upward.
5, the ascending motor 21 is rotated reversely by the angle α and then stopped to start the sheet feeding operation. When the remaining amount of paper on the bottom plate 5 decreases and a signal change of the remaining paper amount detection sensor 105 is detected, the control unit
1 is sequentially started in the normal direction, and each time the sensor 105 changes the signal, the lever 23 is sequentially rotated in the normal direction by the angles α1, α2, α3. When "high-density paper" is selected, the motor is started to rotate forward and the lever 23 at the initial position is rotated forward.
Is reversed by angle β, and lever 2 is
Fix the position of 3. The angle β may be set to 0 by setting the tension spring 32 or the like. Here, the relationship between the rotation angles of the ascending motor 21 is α− (α1 + α2 + α3) = β, and the lever 23 is located at the same position in the case of the plain paper in the area where the remaining paper is the least and in the case of the high density paper. is there.

FIG. 5A is a diagram showing the relationship between the remaining amount of paper and the torque of the rising shaft 3, and FIG. 5B is a diagram showing the relationship between the paper feeding pressure and the remaining amount of paper. The pressing force of the tension spring 32 is set based on high density paper. In this case, when the plain paper is fed, the torque decreases more than an ideal ratio in accordance with the decrease in the remaining amount of the plain paper, so that a feeding failure occurs.
Therefore, in the present embodiment, when plain paper is stacked and fed, the lever 23 is returned in the reverse direction by the angle α from the position detected by the elevation detection sensor 25, so that when the paper is fully loaded, the torque of the ascending shaft 3 is reduced. Although the torque is set to be low, the angle of the lever 23 is sequentially displaced in the direction of raising the bottom plate 5, such as α1, α2, α3, etc., as the remaining amount of paper decreases. That is, each time the signal of the remaining amount detection sensor changes, the sheet feeding pressure is sequentially increased by rotating the ascending motor 21 in the normal direction, and the correction is performed. For this reason, when feeding plain paper, the feed pressure is
As shown in (a), the pressure is gradually reduced while repeatedly increasing and decreasing. However, as shown in (b), the paper pressure can be changed and changed within an appropriate range of the paper pressure. That is, in the case of plain paper, although the paper feed pressure decreases as the remaining amount of paper decreases, the height of the bottom plate 5 is controlled by the control unit 110 based on the remaining amount detection signal from the remaining amount detection sensor 105. Since the correction is sequentially performed, the correction value falls within the range of the appropriate sheet feeding pressure from the time of full loading to the time of paper end. Therefore, the occurrence of paper feeding failure does not occur. When feeding high-density paper,
Since the lever 23 is fixed at the position of the angle β (the appropriate height position of the bottom plate 5), the torque generated on the shaft 3 by the spring force from the tension spring 32 decreases in proportion to the decrease in the load. However, as shown in FIGS. 5A and 5B, the paper supply pressure keeps a substantially constant paper supply pressure within the range of the appropriate paper supply pressure. For this reason, feeding failure of high-density paper does not occur.

Next, FIG. 6 shows another embodiment of the present invention, in which a paper size dial 111 for switching the paper size mounted on an appropriate position of the casing 101 of the paper feed tray 1, for example, on the upper end surface of the front plate is provided. At the same time, a paper type (paper density) switching lever (paper type setting switching means) 112 is provided near the paper size dial 111, and a paper type (paper density) is provided to a control unit on the image forming apparatus main body (or paper feeding device) side. Or one or more photo sensors (paper type detecting means) (not shown) are arranged adjacent to the paper feeding device main body side, and the paper displayed on the paper feeding tray by these photo sensors is arranged. By detecting and discriminating the display unit indicating the type (display consisting of protrusions, holes, and the like that can be detected by the photo sensor), it is possible to set and change the paper type at the time of setting the paper. It has to. Note that the paper type switching lever 112 shown as an example here displays the currently loaded paper type on the display unit 113 on the front surface of the casing 101 by operating, for example, in a direction indicated by an arrow in the drawing, and Control unit 1 on the image forming apparatus main body (or paper feeder) side by a dynamic detection method or an optical detection method
The configuration is such that the switching lever 112 can determine the content of the currently loaded paper by determining the switching content.
The control unit determines the paper type in the paper feed tray based on the settings of the paper type setting switching unit 112, and selects an optimal control method for the paper-lifting motor 21 according to the paper type, particularly the difference in density. ,Execute.

[0013]

As described above, according to the present invention, the optimum paper feed pressure control by changing the paper feed pressure from the paper feed roller according to the difference in the density (weight) of the paper to be fed. , It is possible to prevent the occurrence of a paper feeding failure corresponding to various types of paper having different paper densities. Further, by providing a paper type setting switching means in the paper feeding tray, it is possible to provide a paper feeding device capable of easily switching the setting. That is, according to the first aspect of the invention, the pressure applied to the bottom plate can be changed according to the density of the paper, and the paper supply pressure applied to the paper supply roller can be maintained within a certain range. Paper feed performance can be satisfied. According to the second aspect of the present invention, by providing the paper type setting switching means in the paper feed tray, it is possible to easily perform the paper type switching (switching of the control method of the vertical movement of the bottom plate) due to the difference in density.

[Brief description of the drawings]

FIG. 1 is a front cross-sectional view illustrating an entire configuration of an image forming apparatus including a sheet feeding device according to an embodiment of the present disclosure.

FIG. 2 is a perspective view illustrating a sheet separating unit of the sheet feeding device of the present invention.

FIG. 3 is a perspective view showing a sheet feeding and pressing mechanism of the present invention.

FIG. 4 is a diagram showing a relationship between lever rotation angles in the present invention.

5A is a diagram illustrating a relationship between a remaining amount of paper and a rising shaft torque according to the present invention, and FIG. 5B is a diagram illustrating a relationship between a remaining amount of paper and a feeding pressure according to the present invention.

FIG. 6 is a configuration diagram of another embodiment (paper type switching lever) of the present invention.

FIGS. 7A, 7B and 7C are a plan view, a front view, and a rear view of a paper feed tray, respectively, showing the main components of a conventional paper feed device.

8A is a diagram illustrating a relationship between a remaining amount of paper and a required torque of an ascending shaft in the conventional device, and FIG. 8B is a diagram illustrating a relationship between the remaining amount of paper and a sheet feeding pressure in the conventional device.

[Explanation of symbols]

1 paper feed tray, 3 axes, 4 bottom plate raising arm, 5 bottom plate, 6 paper feed roller, 13 lever, 21 paper raising motor (lift motor), 22 movable shaft, 23 lever, 25
Photo interrupter (elevation detection sensor), 26 compression spring, 32 tension spring (pressure spring), A
Document feeding unit, B reading optical system, C image forming unit, D
Paper feed unit (paper feed device), 100 mounting opening, 101 casing, 105 paper remaining amount detection sensor, 111 paper size dial, 112 paper type (paper density) switching lever (paper type setting switching means).

Claims (2)

[Claims] 1. A sheet feeding tray supported so as to be able to be pulled out in a direction orthogonal to a sheet feeding direction of a transfer sheet stacked on a bottom plate supported vertically and a transfer sheet stacked in the sheet feeding tray Paper feed roller that feeds the top transfer paper one sheet at a time in contact with the top surface of the paper, and pushes up the bottom plate in the paper tray that has been set to press the top transfer paper against the paper feed roller A paper raising mechanism, a control unit for controlling the operation of the paper raising mechanism, and a paper type setting switching unit for setting a paper type stacked on the paper feed tray. A paper-lifting motor that outputs a driving force for pushing up the bottom plate, a lever that rotates up and down by the paper-lifting motor, a lift detection sensor that detects the position of the lever, and operates by the driving force from the paper-lifting motor. An arm that pushes up the bottom plate. For example, the control unit, based on information about the paper type set by the paper type setting switching means, a sheet feeding device and controls the Kamiage motor. 2. The paper feeding device according to claim 1, wherein the paper type setting switching unit is a switching lever provided on the paper feeding tray or a sensor.