US20060033259A1

US20060033259A1 - Paper storage device, paper feeding device, and printing device comprising paper feeding device

Info

Publication number: US20060033259A1
Application number: US11/053,907
Authority: US
Inventors: Akira Yamada
Original assignee: Fujitsu Ltd
Current assignee: Fujitsu Ltd
Priority date: 2004-08-05
Filing date: 2005-02-10
Publication date: 2006-02-16
Also published as: JP2006044891A

Abstract

In a conventional paper feeding device, an excessive load acts on the raising and lowering of a paper feeding table due to friction between the edges of the paper and side face plates in the interior of the paper feeding device. The present invention provides a paper feeding device comprising a paper feeding table on which a plurality of sheets of paper is stacked, elevating unit for raising and lowering the paper feeding table, a positioning side face plate mechanism for aligning at least one edge of the paper placed on the paper feeding table, this mechanism being disposed so as to be removable from the paper feeding table, and side face plate displacing unit for displacing the side face plate mechanism. After the paper is placed on the paper feeding table, and when the elevating unit are to raise the paper feeding table, the side face plate displacing unit displaces the side face plate mechanism away from the at least one aligned edge of the paper.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates to a paper storage device for stacking paper used in a printing device such as a copier, printer, or facsimile which prints alphanumeric characters, images, and so on onto paper, and a paper feeding device for feeding the stacked paper.
2. Description of the Related Art
A printing device such as a copier, printer, or facsimile is provided with a large capacity paper feeding device for supplying the printing device with paper. Paper is stacked in the paper feeding device, and a feeding portion such as a guide roller provided in the printing device supplies one sheet of the paper set on the top of the stack at one time while aligning the position of the paper.
FIG. 1A is an external view of a copier. A plurality of conventional paper feeding devices 1 is stored in the copier 20 in such a manner that when the paper feeding device 1 needs to be replenished with paper, a user draws the paper feeding device 1 out from the copier 20. When the paper feeding device 1 is drawn out, a feeding portion (a guide roller or the like) remains in the interior of the copier 20.
FIG. 1B is a pattern diagram of the paper feeding device 1 in a drawn out state. As shown in FIG. 1B, the paper feeding device 1 has a lift plate 3 onto which paper is stacked, and inner walls 2 a to 2 d disposed so as not to contact the periphery of the lift plate 3. The lift plate 3 is raised and lowered in a vertical direction 12 by elevating unit not shown in the drawing. When paper is placed on the lift plate 3 through an opening portion formed by the upper surface of the paper feeding device 1 and a part of the inner wall 2 d, the lift plate 3 is moved to a position close to a bottom surface 13 by the elevating unit, and when the paper is supplied to the copier 20 via the feeding portion, the lift pate 3 is raised by the elevating unit in accordance with the amount of stacked paper.
FIG. 1C is a sectional view of the paper feeding device 1 when stored in the copier, severed along a parallel plane to the xz plane. When the paper feeding device 1 is drawn out, the user puts paper onto the lift plate 3 through the opening portion. When the paper feeding device 1 is returned to (stored in) the copier 20, the lift plate 3 rises such that the top sheet of paper on the lift plate 3 contacts the guide roller, and then waits for printing to commence. During printing, the paper is supplied to the copier 20 by the rotation of the guide roller.
In the conventional paper feeding device shown in FIG. 1, the inner walls 2 are fixed such that when paper is stacked onto the lift plate, a gap of several millimeters is secured between the inner walls 2 and the periphery of the paper.
Japanese Unexamined Patent Application Publication H3-200643, having a member which removes static electricity from a placing table, Japanese Unexamined Patent Application Publication S60-40332, including a shutter for protecting human hands during paper feeding, and so on are known in the prior art pertaining to a paper feeding device.

SUMMARY OF THE INVENTION

In these conventional examples, however, if the edges of the paper are not properly aligned when replenishing the paper feeding device with paper, a large number of sheets contact the inner walls 2, resulting in an increase in friction between the edges of the paper and the inner walls 2. For example, when the lift plate 3 is raised, the workload is increased due to the amount of friction that is added to the weight of the paper. Further, when a motor is used to raise and lower the lift plate 3, a motor having enough motor power to cope with the amount of friction as well as the weight of the paper must be provided, which leads to an increase in the manufacturing cost.
If the motor power is insufficient, the lift plate 3 may stop at a point during the raising operation, and the frictional force may cause the component (wire, belt, etc.) which transmits the motor power to the lift plate to break. Note that during a lowering operation, unlike the raising operation, the load of the weight of the paper alone is sufficient.
It is therefore an object of the present invention to provide a paper feeding device in which the force required to raise and lower (particularly to raise) a lift plate when replenishing the paper feeding device with paper is substantially constant, regardless of friction between the side face plates of the paper feeding device and the edges of the paper, even when the edges of the paper to be set are not aligned.
According to a first aspect of the present invention, this object is achieved by providing a paper feeding device which has: a paper feeding table on which a plurality of sheets of paper is stacked; elevating unit which raises and lowers the paper feeding table; a side face plate mechanism which aligns at least one edge of the paper placed on the paper feeding table, disposed so as to be able to move away from the paper feeding table; and side face plate displacing unit which displaces the side face plate mechanism. After the paper is placed on the paper feeding table and when the elevating unit are to raise the paper feeding table, the side face plate displacing unit displace the side face plate mechanism away from the at least one aligned edge of the paper.
According to a second aspect of this invention, the aforementioned object is achieved by providing a printing device including: a paper feeding table on which a plurality of sheets of paper is stacked; elevating unit which raises and lowers the paper feeding table; a side face plate mechanism which aligns at least one edge of the paper placed on the paper feeding table, disposed so as to be able to move away from the paper feeding table; and side face plate displacing unit which displaces the side face plate mechanism. After the paper is placed on the paper feeding table and when the elevating unit are to raise the paper feeding table, the side face plate displacing unit displaces the side face plate mechanism away from the at least one aligned edge of the paper.
According to a preferred embodiment of the second aspect of this invention, the paper feeding table can be drawn out, and detection unit are provided for detecting an open state of the paper feeding table, in which the paper feeding table is drawn out, and a closed state of the paper feeding table, in which the paper feeding table is stored. When the detection unit detects transition from the open state to the closed state, the side face plate displacing unit are controlled to displace the side face plate mechanism, whereupon the elevating unit are controlled.
According to a preferred embodiment of the first and second aspects of this invention, the side face plate mechanism includes a first side face plate and a second side face plate facing the first side face plate across the paper feeding table. Further, the side face plate displacing unit includes a pushing mechanism which pushes the first and second side face plates respectively toward the opposing side face plate when paper is placed on the paper feeding table, thereby causing the first and second side face plates to function as positioning side face plates, and a releasing mechanism which releases the first and second side face plates in the opposite direction to the pushing direction when the elevating unit raise the paper feeding table, thereby moving the first and second side face plates away from the paper feeding table.
According to a preferred embodiment of the first and second aspects of this invention, a lower portion of the first and second side face plates is supported rotatably, the first and second side face plates lean in the opposite direction to the pushing direction, the pushing unit includes crank bars which contact the first and second side face plates respectively to cause the leaning first and second side face plates to stand upright, and the releasing unit includes a crank bar displacement portion which displaces the crank bars, contacting the first and second side face plates respectively, in the opposite direction to the pushing direction.
According to a preferred embodiment of the first and second aspects of this invention, first and second bolt blocks are attached to the respective lower portions of the first and second side face plates. The side face plate displacing unit includes first and second screw shafts engaging with the first and second bolt blocks, a motor to rotate the screw shafts, and transmitting unit which transmits the rotary force of the motor to the screw shafts. The transmitting unit transmits the rotary force of the motor to the first and second screw shafts such that the first and second side face plates approach each other when paper is placed on the paper feeding table, and transmit the rotary force of the motor to the first and second screw shafts such that the first and second side face plates move away from each other when the elevating unit raises the paper feeding table.
According to the present invention, when replenishing the paper feeding device with paper, or in other words when the paper feeding device is drawn out from the printing device, the side face plates in the interior of the paper feeding device are fixed, and hence misalignment of the edges of the paper when the paper is supplied can be corrected. When the paper feeding device is stored in the printing device, the side face plates move away from the edges of the paper, thereby easing contact between the paper edges and the side face plates so that the paper feeding table can be raised.
Hence in cases such as when the rear surface of paper that has already been printed on one side is set in the paper feeding device, an excessive load caused by friction between the paper and the side face plates is not applied during an operation to raise or lower the paper feeding table, such as a lift plate, on which the paper is placed, even when the edges of the paper set in the paper feeding device are misaligned. As a result, a substantially constant force can be used to drive an operation to raise or lower the lift plate. Accordingly, there is no need to provide a motor having excessive motor power, and component damage caused by insufficient motor power is prevented.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is an external view of a copier, FIG. 1B is a pattern diagram of a conventional paper feeding device when drawn out from the copier, and FIG. 1C is a sectional view of the conventional paper feeding device;
FIG. 2 is a pattern diagram of a paper feeding device according to an embodiment of the present invention;
FIG. 3 is a view illustrating an example of elevating unit in this embodiment;
FIG. 4A is a sectional view of the paper feeding device when drawn out from a copier, and FIG. 4B is a sectional view of the paper feeding device when stored in the copier;
FIG. 5 is a plan view illustrating an operation of a side face plate 4 b in the paper feeding device of this embodiment, FIG. 5A showing a state in which the paper feeding device is drawn out from the copier, and FIG. 5B showing a state in which the paper feeding device is stored in the copier;
FIG. 6 is a view illustrating another embodiment of the present invention, FIG. 6A being a pattern diagram thereof, and FIG. 6B being an operational diagram thereof; and
FIG. 7 is a block diagram illustrating a printing device according to an embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the present invention will be described below with reference to the drawings. However, the technical scope of the present invention is not limited to these embodiments, and extends to the inventions described in the claims and their equivalents.
FIG. 2 is a pattern diagram of a paper feeding device 1 according to this embodiment. The paper feeding device 1 of this embodiment may be used in a printing device such as a copier, printer, or facsimile, but is shown here as being drawn out from a copier 20 similar to that shown in FIG. 1.
Unlike the conventional example, the paper feeding device of this embodiment includes a side face plate mechanism (having three side face plates in FIG. 2) disposed on the inside of the inner walls of the paper feeding device so as to be able to move away from a paper feeding table. When the paper feeding device 1 is drawn out from the printing device, the side face plate mechanism is fixed so as to serve as a positioning member for aligning at least one of the edges of the paper placed on a lift plate. When the paper feeding device is stored in the printing device and the lift plate is raised in order to supply the paper, the side face plate mechanism is capable of moving away from the paper feeding table such that the play width between the paper edges and the side face plate mechanism increases, thereby realizing a function for reducing friction when the lift plate is raised.
In the paper feeding device 1 of this embodiment, paper is stacked onto a lift plate 3. The top sheet of paper in the paper feeding device is supplied to the printing device by unit of a feeding portion such as a guide roller (see FIG. 1C). In the description of this embodiment, however, the paper feeding device 1 is drawn out from the copier, whereas the feeding portion remains in the interior of the copier 20, and hence the feeding portion is not shown in the drawing.
The paper feeding device 1 in FIG. 2 is drawn out in a drawing direction along a retractable drawing rail 5. Similarly to the paper feeding device shown in FIG. 1, a user puts paper onto the lift plate 3 through an opening portion (defined by the upper face of the paper feeding device 1 and a part of an inner wall 2 d) formed when the paper feeding device 1 is in a drawn out state. Unlike FIG. 1, however, movable side face plates 4 a to 4 c are provided on the inside of the inner walls 2 a to 2 c.
The side face plate 4 a has a rotatable fulcrum 8 at the lower portion thereof, and if a crank bar 6 is absent, the side face plate 4 a moves toward the inner wall 2 a about the fulcrum 8. The crank bar 6 is an angled or rod-form member or the like having a C shape (in other words, a transformed E shape made by deleting center one of three horizontal lines of character “E”), which serves to push the side face plate 4 a in the direction of the opposing side face plate 4 c when the side face plate 4 a attempts to move toward the inner wall 2 a while the paper feeding device 1 is drawn out from the printing device (in this case, the copier 20).
In the paper feeding device 1 of this embodiment, the side face plate 4 a is made to stand upright when the paper feeding device 1 is drawn out, by adjusting the dimension of the crank bar 6. Similarly to the side face plate 4 a, when the paper feeding device 1 is drawn out, the side face plate 4 c is pushed in the direction of the opposing side face plate 4 a by a crank bar (on the side face plate 4 c side) not shown in FIG. 2, and thus made to stand upright.
A side face plate 4 b is connected by its lower portion to a bottom face 13, and is therefore capable of leaning in the direction of the inner wall 2 b. When the paper feeding device 1 is drawn out from the copier, the side face plate 4 b is fixed between the side face plate 4 a and the side face plate 4 c which are pushed in the direction of their respective opposing side face plates. As shown in FIG. 2, the ends of the side face plate 4 a and side face plate 4 c on the inner wall 2 b side are bent. When the paper feeding device 1 is stored in the copier, the side face plate 4 a and side face plate 4 c move toward the inner wall 2 a and the inner wall 2 c respectively, and hence if the ends were not bent, the side face plate 4 b would touch the inner wall 2 b. However, the side face plate 4 b, which is capable of leaning toward the inner wall 2 b side, is supported by the bent part, and therefore does not contact the inner wall 2 b.
When the paper feeding device 1 of this embodiment is drawn out, the position at which the side face plate 4 b stands upright corresponds to the position at which the side face plate 4 a and side face plate 4 c start to bend. Hence when the paper feeding device 1 is drawn out from the copier 20, the side face plates 4 a to 4 c can be fixed, and used thus as a positioning member for aligning the edges of the paper that is placed on the lift plate 3.
The lift plate (paper feeding table) 3, which is raised and lowered in a vertical direction from the bottom face 13, is connected to a motor-driven cylinder, gear, belt, wire, or the like, not shown in the drawing, serving as elevating unit for raising and lowering the lift plate 3. The elevating unit for raising and lowering the lift plate 3 may be of a lifting type that supports and raises the lift plate 3 from below, a hanging type that supports the lift plate 3 from above, or an holding type that supports the lift plate 3 from the side.
FIG. 3 is a view illustrating an example of the elevating unit of the lift plate 3. The lift plate 3 is supported by four wires 36, one end of each wire being wrapped around a pulley shaft 33 via rollers 35. The rotary force of a motor 31 is transmitted to a bevel gear 34 via a gear shaft, whereby the bevel gear 34 is driven such that the pulley shaft 33 rotates. This causes the wires 36 to be wound around the pulley shaft 33.
In FIG. 3, when the motor 31 rotates in the direction of the arrow, the lift plate 3 rises. When the excitation of the motor 31 is cut, the lift plate 3 falls under its own weight. In this manner, the lift plate 3 can be raised and lowered.
The lift plate 3 is provided with protrusions corresponding to the number of wires for connecting the wires 36 to the lift plate 3. The wires 36 are stretched in positions between the side face plate 4 a and the inner wall 2 a. Although not shown in FIG. 2, grooves designed to prevent interference with the motion of the protrusions are cut into the side face plate 4 a on the left and right sides of the crank bar 6 so that the wires do not catch on the side face plate 4 a when the lift plate 3 moves up and down. Similar grooves are cut into the side face plate 4 c on the left and right sides of the crank bar 7.
Next, operations of the side face plates 4 a, 4 c when the paper feeding device 1 is stored in the copier 20 will be described using sectional views of the paper feeding device 1 when drawn out from the copier 20 and when stored in the copier 20.
FIG. 4A is a sectional view of the paper feeding device 1 when drawn out from the copier 20, and FIG. 4B is a sectional view of the paper feeding device 1 when stored in the copier 20. Both FIG. 4A and FIG. 4B are sectional views showing the paper feeding device severed along a parallel plane to the xz plane (see FIG. 2).
In FIG. 4A (when the paper feeding device 1 is drawn out from the copier 20), the side face plate 4 a, which is rotatably supported by the fulcrum 8 and attempting to move toward the inner wall 2 a, and the inner face plate 4 c, which is rotatably supported by a fulcrum 9 and attempting to move toward the inner wall 2 c, are pushed toward the respective opposing inner wall side by the C-shaped (or transformed E-shape) crank bar 6 and the L-shaped crank bar 7 respectively, and as a result, the side face plate 4 a and side face plate 4 c stand upright. The crank bar 6 and crank bar 7 are connected by a point of action 11. One end of the crank bar 6 (on the opposite side to the side which pushes the side face plate) is connected to a wall face in the interior of the copier 20, and work as a retractable crank bar displacement portion. The crank bar 7 is an angled or rod-form member or the like which is rotatable about a fulcrum 10.
In FIG. 4B (when the paper feeding device 1 is stored in the copier 20), one end of the crank bar 6 impinges on a wall face 15 of the copier 20 such that the crank bar displacement portion shorten, causing the crank bar 6 to be pushed leftward. As a result, the force with which the crank bar 6 pushes the side face plate 4 a weakens, thereby releasing the side face plate 4 a such that the side face plate 4 a moves in the direction of the inner wall 2 a with the fulcrum 8 as an axis. Thus the side face plate 4 a leans in the direction of the inner wall 2 a. As the crank bar 6 is pushed leftward, the action point 11 also deviates leftward, causing the crank bar 7 to rotate about the fulcrum 10 and thereby lean to the right. As a result, the force with which the crank bar 7 pushes the side face plate 4 c weakens, thereby releasing the side face plate 4 c such that the side face plate 4 c moves in the direction of the inner wall 2 c with the fulcrum 9 as an axis. Thus the side face plate 4 c leans in the direction of the inner wall 2 c. In this manner, the crank bar displacement portion causes the crank bars 6, 7 to release the respective inner walls 4 a, 4 c.
As described in FIG. 3, the wires 36 are stretched in positions between the side face plate 4 a and inner wall 2 a, and the side face plate 4 c and inner wall 2 c*. In FIGS. 4A and 4B, the wires 36 stretching from the lift plate 3 are led to the roller 35 (see FIG. 3) which is not shown in these drawings. Next, the side face plate 4 b will be described.
FIG. 5 is a plan view illustrating an operation of the side face plate 4 b in the paper feeding device 1 of this embodiment. FIG. 5A shows a state in which the paper feeding device 1 is drawn out from the copier 20, and FIG. 5B shows a state in which the paper feeding device 1 is stored in the copier 20. In FIG. 5A, the side face plate 4 a and side face plate 4 c are standing upright, and hence the side face plate 4 b is fixed between the side face plate 4 a and side face plate 4 c at the bending positions thereof. Hence the side face plate 4 b is also illustrated in an upright state. The area inside the broken line within the region surrounded by the upright side face plates 4 a to 4 c and the inner wall 2 d is a paper placing area 44 in which paper is stacked. In reality, the position of each sheet of paper differs so as to protrude from the broken line.
FIG. 5B shows a state in which the side face plate 4 a and side face plate 4 c are leaning, as shown in FIG. 4B, the side face plate 4 a moving in the direction of an arrow 41 and the side face plate 4 c moving in the direction of an arrow 43. The holding force with which the side face plate 4 b is supported weakens, and hence the side face plate 4 b leans in the direction of the inner wall 2 b, thus moving in the direction of an arrow 42 along the bent parts of the side face plate 4 a and side face plate 4 c. Hence it can be seen that when the paper feeding device 1 is stored in the copier 20, the gaps between the paper placing area 44 shown by the broken line and the side face plates 4 a to 4 c are wider than when the paper feeding device 1 is drawn out from the copier 20.
As shown in FIGS. 4 and 5, when the paper feeding device 1 is stored in the copier 20, the crank bars 6, 7 displace the side face plates 4 a, 4 c such that the edges of the paper are moved away from the side face plates 4 a to 4 c in the interior of the paper feeding device. As a result, friction between the edges of the paper and the side face plates 4 a to 4 c in the interior of the paper feeding device is greatly reduced, even when the lift plate 3 is raised or lowered, and hence the lift plate can be raised and lowered by a constant force. The friction that is generated between the inner wall 2 d and the paper edge is not sufficient to affect the raising of the lift plate 3.
Note that when the side face plates 4 a to 4 c are separated during the raising or lowering of the lift plate, friction between the stacked sheets of paper prevents added paper from moving in the interior of the paper feeding device 1 so as to become adhered to the side face plates or sliding under another sheet of the stacked paper.
FIG. 6 is a view illustrating another embodiment of the present invention, wherein the side face plate mechanism is composed of two side face plates. In this other embodiment, the two side face plates 4 a, 4 c are displaced from the paper feeding table by a motor.
FIG. 6A is a pattern diagram thereof, and FIG. 6B is an operational diagram thereof. The driving force that is generated by the rotation of a motor 51 is transmitted to screw shafts 53 extending to the left and right via a bevel gear 52, causing the screw shafts 53 to rotate. Note that in FIG. 6, the bent parts of the side face plates 4 a, 4 c are not shown.
Bolt blocks 54 to which either the side face plate 4 a or the side face plate 4 c is fixed are fitted over the screw shafts 53. The bolt blocks 54 are members which serve as nuts. If a screw can rotate in fixed position, when the screw rotate, a nut fitted over the screw are moved by the rotation of the screw. The same is true for bolt blocks 54 and screw shafts 53. When the screw shafts 53 rotate, the bolt blocks 54 move, causing the side face plates 4 a, 4 c that are fixed to the bolt blocks 54 to move in parallel.
When the rotary driving force of the motor in a direction α is transmitted to the bevel gear 52 as shown in FIG. 6B, the screw shafts 53 rotate in a direction α′, as a result of which the bolt blocks 54 approach the bevel gear 52 and the side face plates 4 a, 4 c move in parallel in a direction α″. Conversely, when the rotary driving force of the motor in a direction β is transmitted to the bevel gear 52, the screw shafts 53 rotate in a direction β′, as a result of which the side face plates 4 a, 4 c move in parallel in a direction β″.
Hence when the paper feeding device 1 is drawn out from the copier 20, the motor 51 is driven such that rotary driving force is transmitted in the direction α of FIG. 6, and when the paper feeding device 1 is stored in the copier 20, the motor 51 is driven such that rotary driving force is transmitted in the direction β of FIG. 6. As a result, an identical effect to that achieved with the paper feeding device of the first embodiment can be obtained.
By driving the side face plates using a motor as shown in FIG. 6, the side face plates 4 a to 4 c can be moved after a predetermined time period following storage of the paper feeding device 1 in the printing device, instead of being moved at the same time as the paper feeding device 1 is stored in the printing device. Moreover, the motor 51 may also be used in an operation to raise or lower the lift plate.
Note that in FIG. 6, a bevel gear is used as transmitting unit for transmitting the rotary force of the motor to the screw shafts 53, but this operation may be realized using a wire, a block, a belt, a pulley, or similar.
According to this other embodiment described above, when the lift plate 3 is raised, the side face plates 4 a, 4 c are displaced by a side face plate displacement portion, such as the crank bars 6, 7 or the bolt blocks 54, for displacing the side face plates, and hence there is no need to take into account the amount of friction between the paper placed on the lift plate 3 and the side face plates. Thus the force required to raise and lower the lift plate 3 is determined by the weight of the paper, and is therefore substantially constant, enabling raising and lowering operations to be performed with stability. When a motor is used to raise and lower the lift plate, the motor output is modified to an appropriate level, thereby contributing to an improvement in the quality of the paper feeding device and printing device. Since margins such as support shafts for the wires or pulley used as a part of the elevating unit, frame reinforcement, and soon can be held to a minimum, an appropriate cost can be realized.
Note that in the above description, the side face plate mechanism has a plurality of side face plates, and all of the side face plates are moved away from the paper edges. However, friction can be reduced sufficiently even when at least one of the plurality of side face plates including the side face plate mechanism is moved away from the paper feeding table as the lift plate 3 is raised or lowered, and thus the effect of making the force required to raise the lift plate substantially constant can be realized. Further, the shape of the paper is not limited to a rectangular shape, and the side face plate mechanism may be disposed in alignment with the shape of the paper. Note that similar effects to those of the embodiment described above are achieved when the operating procedure of the side face plates and the lift plate 3, described in this embodiment, is realized as a method.
Next, the printing device having the paper feeding device of this embodiment will be described.
FIG. 7 is a block diagram of the printing device of this embodiment. The printing device in FIG. 7 includes a control unit 71 for controlling elevating unit 74 and side face plate displacing unit 73 provided in the paper feeding device, and detection unit 72 for detecting whether the paper feeding device is drawn out from or stored in the printing device.
The detection unit 72 are realized using an optical sensor or the like, for example, provided in a location that cannot be seen when the paper feeding device is stored but can be seen when the paper feeding device is drawn out. For example, the optical sensor may be disposed at the location of an X mark 75 in FIG. 2. The detection unit 72 may be realized by other unit. In the case of a printing device in which the paper feeding device is held in a stored state by a holding mechanism composed by a latch or the like and drawn out by releasing the latch, for example, a drawn out state and a stored state can be detected by a switch which switches on and off according to the latch position.
Hence when the paper feeding device is stored, the control unit 71 displaces the side face plate displacing unit 73 before raising the elevating unit 74 such that the side face plate mechanism is moved away from the paper feeding table, and thus friction generated when the lift plate 3 is raised can be reduced. An identical effect is achieved when the operating procedure executed in the control unit is realized as a program executed in a CPU.

Claims

1. A paper feeding device comprising:

a paper feeding table on which a plurality of sheets of paper is stacked;

elevating unit which raises and lowers the paper feeding table;

a side face plate mechanism which aligns at least one edge of the paper placed on the paper feeding table, disposed so as to be able to move away from the paper feeding table; and

side face plate displacing unit which displaces the side face plate mechanism,

wherein, after the paper is placed on the paper feeding table and when the elevating unit are to raise the paper feeding table, the side face plate displacing unit displaces the side face plate mechanism away from the at least one aligned edge of the paper.

2. The paper feeding device according to claim 1,

wherein the side face plate mechanism includes a first side face plate and a second side face plate facing the first side face plate across the paper feeding table, and

the side face plate displacing unit include:

pushing unit which pushes the first and second side face plates respectively toward the opposing side face plate when the paper is placed on the paper feeding table; and

releasing unit which releases the first and second side face plates in the opposite direction to the pushing direction when the elevating unit raises the paper feeding table.

3. The paper feeding device according to claim 2,

wherein a lower portion of the first and second side face plates is supported rotatably,

the first and second side face plates lean in the opposite direction to the pushing direction,

the pushing unit include crank bars which contact the first and second side face plates respectively to cause the leaning first and second side face plates to stand upright, and

the releasing unit include a crank bar displacement portion which displaces the crank bars, contacting the first and second side face plates respectively, in the opposite direction to the pushing direction.

4. The paper feeding device according to claim 2,

wherein first and second bolt blocks are attached to the respective lower portions of the first and second side face plates,

the side face plate displacing unit include first and second screw shafts engaging with the first and second bolt blocks, a motor to rotate the screw shafts, and transmitting unit which transmits the rotary force of the motor to the screw shafts, and

the transmitting unit transmits the rotary force of the motor to the first and second screw shafts such that the first and second side face plates approach each other when the paper is placed on the paper feeding table, and transmit the rotary force of the motor to the first and second screw shafts such that the first and second side face plates move away from each other when the elevating unit raises the paper feeding table.

5. The paper feeding device according to claim 4,

wherein the transmitting unit includes a motor side gear attached to a rotary shaft of the motor, and first and second gears attached to the first and second screw shafts respectively and disposed such that the rotation of the motor side gear is transmitted to the first and second screw shafts simultaneously.

6. A printing device comprising:

a paper feeding table on which a plurality of sheets of paper is stacked;

elevating unit which raises and lowers the paper feeding table;

side face plate displacing unit which displaces the side face plate mechanism,

7. The printing device according to claim 6,

wherein the paper feeding table can be drawn out,

the printing device includes detection unit which detects an open state of the paper feeding table, in which the paper feeding table is drawn out, and a closed state of the paper feeding table, in which the paper feeding table is stored, and

when the detection unit detects transition from the open state to the closed state, the side face plate displacing unit are controlled to displace the side face plate mechanism, whereupon the elevating unit are controlled.

8. The printing device according to claim 6,

the side face plate displacing unit include:

9. The printing device according to claim 8,

10. The printing device according to claim 8,

11. The printing device according to claim 10, wherein the transmitting unit includes a motor side gear attached to a rotary shaft of the motor, and first and second gears attached to the first and second screw shafts respectively and disposed such that the rotation of the motor side gear is transmitted to the first and second screw shafts simultaneously.