JPH09255163A - Sheet material feeding device, image forming device, and image reading device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the stop position accuracy of a sheet material loading plate irrespective of a sheet material loading amount on the sheet material loading plate and to provide a high position maintaining ability for preventing the lowering of the sheet material loading plate even if the sheet material loading plate is pushed down from its highest position. SOLUTION: A document pushing-up lever 7 (vertical moving means) is set such that as a document loading plate 2 (sheet material loading means) and a feeding roller 3 (feeding means) are brought close to each other in a relative positional relationship therebetween, the vertical moving amount of the document loading plate 2 is reduced against a driving amount inputted by the driving motor 5 (driving control means) of the document pushing-up lever 7 and when these sections are brought closets to each other, the document pushing-up lever 7 supports the document loading plate 2 in a position in the vicinity of a vertical moving amount of 0.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet material feeding device for raising and lowering a sheet material loading means to bring the loaded sheet material into contact with a feeding means and feed it by an operator. The present invention relates to a sheet material feeding device capable of performing paper. In particular, it is applied to image forming apparatuses such as printers, copying machines, and facsimile machines.

[0002]

2. Description of the Related Art A conventional sheet material feeding device will be described with reference to FIGS. First, in the sheet material feeding device shown in FIG. 7, when the sheet material is set, the sheet material stacking plate 102 is in a state shown by a chain double-dashed line. The sheet material S is the paper feed tray 101.
Also, the sheet material stacking plate 102 is set on the sheet material stacking plate 102, and the sheet material stacking plate 102 is pushed up by the compression spring 115 to the position shown by the solid line around the fulcrum 102a by the compression spring 115.

As the sheet material S rises, the arm portion of the sheet material detection lever 104, which contacts the sheet material S and rotates about the fulcrum 104a, shuts off the photo sensor 108, so that the stacked sheet material S is placed. It is detected that the uppermost surface position of the sheet is in contact with the vertically movable feeding roller 103, and the feeding roller 103 rotates in the direction of the arrow in FIG. Arrow S101 in FIG. 7 from S
Is fed in the direction.

The sheet material feeding device shown in FIG. 8 is the same as that shown in FIG. 7 until the sheet material S is set. By the feeding operation start signal, the output shaft 106 of the drive motor 105 rotates counterclockwise in FIG.
The sheet material base lifting lever 107 moves from the position shown by the chain double-dashed line to the position shown by the solid line, and along with this, the sheet material stacking plate 1
02 rotates about the fulcrum 102a and is pushed up from the position indicated by the chain double-dashed line to the position indicated by the solid line.

As the sheet material S rises, the arm portion of the sheet material detection lever 104, which comes into contact with the sheet material S and rotates about the fulcrum 104a, shuts off the photo sensor 108, whereby the stacked sheet material S is placed. It is detected that the uppermost surface of the sheet is in contact with the vertically movable feeding roller 103, and the feeding roller 103 rotates in the direction of the arrow in FIG. The sheet is fed from S in the direction of arrow A101 in FIG.

The sheet material S is fed to the sheet material stacking plate 1
02 sheet material S on 02, sheet material detection lever 104
When is removed from the position where the photosensor 108 is blocked, the drive motor 105 is driven to keep the uppermost surface position of the sheet material S substantially constant.

Further, the photosensors 116 and 1 shown in FIG.
Reference numeral 17 denotes a cut-and-raised portion 10 of the sheet material platform push-up lever 107.
The lowermost and uppermost positions of the sheet material and the stacking plate 102 are detected by being cut off by 7a, and the sheet material stacking plate 10
I try not to let 2 go up too much and not go down too much.

[0008]

However, in the conventional example shown in FIG. 7, the elastic force of the compression spring 115 is used to press the sheet material S against the feeding roller 3,
Since the weight per unit area acting on the sheet material stacking plate 102 is different due to the difference in size and weight density of the sheet material S stacked on the sheet material stacking plate 102, the feeding roller 103 abutting on the sheet material S is different. There is a problem that a constant and stable feeding pressure cannot be given.

In the conventional example shown in FIG. 8, the motor 1 is used.
Sheet material table push-up lever 1 connected to the output shaft 106 of 05
The sheet material stacking plate 102 is pushed up by 07 and brought into contact with the feeding roller 103.
By adjusting the rotation angle of 7, the pressure contact force between the sheet material S and the feed roller 103 can be stably maintained within a certain range regardless of the weight of the sheet material S stacked on the sheet material stacking plate 102.

However, as the sheet material S stacked on the sheet material stacking plate 102 advances as the feeding operation progresses,
It gradually decreases. In other words, the weight of the sheet material S, which is the load of the sheet material platform lifting lever 107, tends to gradually decrease as the feeding operation progresses.

Therefore, each time the level of the uppermost sheet material is lowered, the drive motor 105 rotates and the sheet material stacking plate 10 is rotated.
2 is pushed up, but the drive motor 105 at this time
The load applied to the sheet becomes smaller as the feeding operation progresses.

Operation / non-operation of the sheet material stacking plate pushing mechanism,
That is, since the drive motor 105 is turned on / off by a detection signal from the level detection means of the sheet material S, when the uppermost sheet material is raised to a predetermined level, the drive motor 105 is stopped. In this case, the load applied to the drive motor 105 is the sheet material stacking plate 102.
The drive motor 105 immediately stops when the stacking amount is large, but the drive motor 105 rotates due to the inertia when the stacking amount is small, and the top position is accurately measured. However, there is a problem that the sheet material cannot be positioned at a predetermined level.

Further, if the drive motor 105 of the type having a small inertia is used, the above problem is expected to be solved, but the cost is inevitable.

Further, since the drive motor 105 drives the sheet material base lifting lever 107 directly via the output shaft 106, if the operator forcibly pushes the sheet material stacking plate 102 during the feeding operation. However, there is a problem that the drive motor 105 is overloaded and the motor 105 is locked. Even if a friction transmission means (not shown) is provided in the drive transmission means for transmitting the drive from the motor 105 to the sheet material base lifting lever 107 in order to solve this problem, it is possible to continuously feed the same sheet material stacking plate 102. When the paper mode and the manual feed mode are performed, the sheet material stacking plate 102 is used as a manual feed guide when manually feeding the sheet, so that the sheet material stacking plate 10 is fed when the operator feeds the sheet material S.
There is a problem that 2 is pressed and lowered, and the feeding pressure by the feeding roller 103 is lowered to cause feeding failure.

The present invention has been made to solve the above-mentioned problems of the prior art, and an object thereof is to stop the sheet material stacking plate regardless of the amount of the sheet material stacking on the sheet material stacking plate. An object of the present invention is to provide a sheet material feeding device capable of improving the positional accuracy and maintaining good feeding of a sheet material with a simple structure and at a low price.

In addition, when the sheet material stacking plate is at the uppermost position, that is, even when an operator pushes down the sheet material stacking plate during manual feeding, it has a high position holding characteristic so that it does not go down, which is good. It is possible to maintain the feeding of various sheet materials.

[0017]

In order to achieve the above object, according to the present invention, sheet material stacking means for stacking sheet material and sheet material on the sheet material stacking means are abutted and fed. Feeding means, elevating means for supporting the sheet material stacking means so as to be able to move up and down, drive control means for driving this elevating means, and detecting the highest position of the sheet material stacked on the sheet material stacking means. A sheet material position detecting means, wherein the drive control means adjusts the relative positional relationship between the sheet material stacking means and the sheet feeding means in accordance with the detected highest position of the sheet material. As the relative position relationship between the sheet material stacking means and the feeding means approaches, the elevating means reduces the amount of elevating the sheet material stacking means with respect to the drive amount input by the drive control means of the elevating means. Together, set to support at the vicinity of positions corresponding with the amount of vertical movement is 0 when closest.

According to this, the relative positional relationship between the sheet material stacking means and the feeding means approaches, the sheet material decreases, the load applied to the driving means decreases, and the driving amount increases due to the inertia of the driving means. However, since the vertical movement amount of the sheet material stacking means is small, the stop position accuracy of the sheet material stacking means is improved.

Sheet material stacking means for stacking sheet materials,
Feeding means for contacting and feeding the sheet material on the sheet material stacking means, elevating means for elevating and lowering while supporting the sheet material stacking means, drive control means for driving the elevating means, and the sheet material A sheet material position detecting means for detecting the uppermost position of the sheet material stacked on the stacking means, and the drive control means according to the detected uppermost position of the sheet material, and the sheet material stacking means and the feeding means. In the sheet material feeding device for adjusting the relative positional relationship between the sheet material stacking means and the feeding means, the elevating means is input by the drive control means of the elevating means. The sheet material stacking means can be stopped in the vicinity of a position where the ascending / descending amount of the sheet material stacking means with respect to the driving amount is zero.

According to this, the elevating means is stopped in the vicinity of the position where the elevating amount of the sheet material stacking means becomes 0, and the sheet material stacking means is fixed.

A continuous paper feed mode in which a plurality of sheet materials stacked on the sheet material stacking means are separated and fed one by one, and 1 is placed on the sheet material stacking means at the stop position where the lifting amount is 0. A manual paper feed mode for stacking and feeding sheet materials sheet by sheet is provided.

The elevating means is provided with a cam means having a contour curve for supporting the sheet material stacking means, and when the sheet material stacking means is in a stopped state where the ascending / descending amount is 0, the large diameter portion of the contour curve of the cam means is the sheet. The pressure receiving portion receives a force for supporting the material stacking means, and its pressure receiving direction is substantially coincident with the direction connecting the large diameter portion and the cam shaft.

According to this, when the sheet material stacking means is located at the uppermost position, the applied force is transmitted to the cam shaft via the pressure receiving portion of the cam without a turning moment,
The sheet material stacking means is fixed without dropping from the uppermost position.

The elevating means is provided with a link mechanism having a lever member which is connected to the drive control means and rotates, and a link member which connects the lever member and the sheet material stacking means.
The link mechanism is in a state in which the lever member and the link member are lined up in a straight line when the sheet material stacking unit at which the lifting amount is 0 is stopped and the pressure receiving direction from the sheet material stacking unit is in the straight line. It is almost the same as the lined-up direction.

According to this, since the force applied when the sheet material stacking means is positioned at the uppermost position is supported by the link mechanism arranged in a straight line, the link mechanism is not displaced, and the sheet material stacking means does not move. It is fixed without descending from the upper position.

The drive control means is provided with a transmission force regulation means for regulating transmission of an excessive force inputted from the sheet material stacking means via the elevating means.

According to this, when an excessive load is applied when the sheet material stacking means is located at a position other than the uppermost position, the transmission force restricting means applies an excessive load to the elevating means and the drive control means and damages them. To prevent.

It is also preferable that the transmission force regulating means is provided with a friction transmission mechanism for regulating the transmission force to a predetermined magnitude by the friction generated between the two members in close contact with each other.

It is also preferable that the feeding means is constructed so as to be movable so as to come into contact with the sheet material placed on the sheet material stacking means in response to a change in the uppermost position of the sheet material.

According to this, the feeding means moves in contact with the sheet material in response to the change in the uppermost position of the sheet material, so that stable feeding can be performed.

It is preferable that the sheet material position detecting means also functions as a sheet material presence / absence detecting means for detecting the highest position of the sheet material and detecting the presence / absence of the sheet material placed on the sheet material stacking means. .

In the manual feed mode, it is also preferable to start feeding the sheet material when the sheet material position detecting means detects the sheet material with the sheet material stacking means stopped at the uppermost position.

The image forming apparatus includes the sheet material feeding device and an image forming means for forming an image on the sheet material conveyed to the sheet material feeding device.

The image reading device includes the above-mentioned sheet material feeding device and an image reading means for reading the image information of the sheet-like document conveyed to this sheet material feeding device.

[0035]

BEST MODE FOR CARRYING OUT THE INVENTION A sheet material feeding device to which the present invention is applied is provided in various devices that handle various sheet materials, and as an example, image formation for forming an image on a sheet material to be fed. The image forming apparatus provided with the means or the sheet material to be fed is a document, and the invention can be applied to an image reading device or the like for reading an image of the document by the image reading means.

In the embodiment of the present invention, the sheet material to be fed is an original, and the sheet material feeding device is provided in an image reading device for reading image information of the sheet material.

(First Embodiment) An outline of an image reading apparatus will be described with reference to FIG. In FIG. 4, when a document S as a sheet material is stacked on a document stacking plate 2 which is a sheet material stacking unit and a reading start command is sent to the image reading apparatus, the document stacking plate 2 is moved by an elevating unit and a drive control unit described later. Rise,
The feeding of the document S is started.

First, the document S is sent between the feed roller 20 and the separation roller 21 by the feeding roller 3 as a feeding means. Only the uppermost first original S is sent to the next roller pair 22 due to the difference in frictional force between the feed roller 20 and the separation roller 21 and the original S, and the original S is further read by the reading unit R by the roller pair 23. Reach

In the reading section R, the images illuminated by the illuminating means 28a, 28b are converted into electric signals by the reading means 29a, 29b and further converted into digital data. The document S that has been read is discharged to the discharge unit 27 by the roller pairs 24, 25, and 26. By including an image forming means for forming the read digital data on a sheet material as a recording medium, it is possible to function as an image forming apparatus.

Next, the features of the sheet material feeding device according to the first embodiment of the present invention will be described with reference to FIGS. 1 and 2. 1 and 2 are cross-sectional configuration explanatory views of a sheet material feeding device embodying the present invention.

A document stacking plate 2 that is rotatable around a fulcrum 2a is continuously provided on the feeding tray 1, and a document S
Are stacked on the feed tray 1 and the document stacking plate 2.

A part of the contour curve of the cam of the document table pushing-up lever 7 as the elevating means and the cam means is in contact with the lower surface of the end portion of the document stacking plate 2. The platen pushing-up lever 7 is fixed to a platen pushing-up shaft 10.

Then, by the action of the friction transmission mechanism M1 as transmission force regulating means shown in FIG. 3 and described later, the document table pushing-up shaft 1 serving as the cam shaft from the drive motor 5 serving as the drive control means.
The driving force is transmitted to 0, and the document table pushing-up lever 7 rotates around the document table pushing-up shaft 10 to push up the document stacking plate 2.

When the original stacking plate 2 is pushed up, the uppermost original S among the originals S stacked on the original stacking plate 2 becomes rotatable around a fulcrum 16a arranged near the leading end of the original S. The original S is supported by the feed roller support member 16 which is axially supported, abuts on the feed roller 3 which can move up and down, and the feed roller 3 rotates in the direction of arrow g in FIG.
Are fed in the direction of arrow A1.

Platen push-up lever 7 and platen push-up shaft 1
In the lower part of 0, the uppermost position regulating slope 12a that regulates the tilt angle of the document table pushing-up lever 7 corresponding to the uppermost position of the document stacking plate 2 and the document table corresponding to the lowest position of the document stacking plate 2 are provided. A stopper 12 having a lowermost position regulating slope 12b for regulating the inclination angle of the push-up lever 7 is arranged.

When the document table pushing-up lever 7 rotates about the document table pushing-up shaft 10 in the direction of the arrow b in FIG. 1, the projection 7a of the document table pushing-up lever 7 contacts the uppermost position regulating slope 12a of the stopper 12. By making contact with each other, the rotation operation of the document table pushing-up lever 7 is suppressed, and the document stacking plate 2 is held at the uppermost position.

When the document table pushing-up lever 7 rotates about the document table pushing-up shaft 10 in the direction of the broken line arrow c in FIG. 1 by a predetermined angle, the projection 7a of the document table pushing-up lever 7 is stopped by the stopper 12.
By making contact with the lowermost position regulating slope 12b, the rotation of the original table pushing-up lever 7 is suppressed, and the original stacking plate 2 is held at the lowermost position.

Next, the friction transmission mechanism for transmitting the drive from the drive motor 5 to the platen push-up shaft 10 will be described with reference to FIG. In FIG. 3, the output shaft 6 connected to the drive motor 5 and the output gear 9 are mounted substantially integrally. Further, as described above, the document table pushing-up lever 7 is fixedly attached to the document table pushing-up shaft 10, and is fitted to the document table pushing-up shaft 10 at a position facing the output gear 9.
The friction gear 11 is arranged so as to be rotatable with respect to zero and one end of which is regulated in position in the direction of the shaft 10 by a locking portion 11a.

At the other end of the friction gear 11, a friction member 13 fitted to the document table pushing-up shaft 10 and rotatable with respect to the shaft 10 is attached substantially integrally.

The friction member 1 is fitted to the document table pushing-up shaft 10.
The pressing member 14 adjacent to 3 is attached so as to be movable in the direction of the shaft 10 and is configured to integrally rotate in the rotation direction of the platen lifting shaft 10.

A spring 15 provided at the end of the document table lifting shaft 10 constantly presses the pressing member 14 against the friction member 13 along the document table lifting shaft 10 and the pressing member 14 and the friction member 13. Due to the pressure-contact friction between the two, the platen push-up shaft 10 and the friction gear 11 normally rotate integrally.

Therefore, when the output shaft 6 and the output gear 9 are rotated by the drive of the drive motor 5, the friction gear 11 meshing with the output gear 9 is rotated, and the pressing member 14 and the document table pushing-up shaft 10 are mediated by the friction member 13. , Platen push-up lever 7
Rotates up to a transmission force of a predetermined magnitude.

With the above-described structure, in the initial state of the document feeding operation, the document stacking plate 2 and the document table pushing-up lever 7 are in contact with the lowermost position regulating slope 12b of the stopper 12 in FIG. It is in the position shown by. The document S to be fed in this state is set on the feeding tray 1 and the document stacking plate 2.

The drive motor 5 is driven by the feeding operation start signal, the output shaft 6 connected to the drive motor 5 rotates, and the output gear 9 which is substantially integrated with the output shaft 6 is shown in FIG. It rotates in the direction of arrow d. Then, the friction gear 11 meshing with the output gear 9 rotates in the direction of arrow e, and the document table pushing-up shaft 10 also rotates in the same direction via the above-mentioned transmission force restricting means.

Then, the platen push-up lever 7 attached to the platen push-up shaft 10 rotates in the direction of the arrow b in FIG. 1 to move from the position shown by the chain double-dashed line to the position shown by the solid line. Along with this, the document stacking plate 2 rotates about the fulcrum 2a in the direction of arrow f in FIG. 1 and moves from the position indicated by the chain double-dashed line to the position indicated by the solid line.

Then, the document detection lever 4 as a sheet material position detecting means pivotally supported about the fulcrum 4a comes into contact with the uppermost surface of the document S and is pushed up as the document S moves up. By moving and shutting off the document detection photosensor 8, the uppermost position of the stacked documents S is located at the position (state position shown in FIG. 1) abutted by the weight of the feeding roller 3. Detect that.

The original detection lever 4 and the original detection photosensor 8 can also serve as a sheet material position detection means for detecting the position of the uppermost original S on the original stacking plate 2 and a sheet material presence / absence detection means. It is something.

Then, a rotation driving force for rotating the feeding roller 3 in the direction of arrow g in FIG. 1 is given from a driving means (not shown), and the uppermost original of the original S is fed in the direction of arrow A1 in FIG. . The drive motor 5 is stopped at the same time when the document detection lever 4 shuts off the document detection photosensor 8, and the document table pushing-up lever 7 is held in this state to hold the document stacking plate 2 at a constant height.

When the originals S are sequentially fed, the originals on the original stacking plate 2 decrease, and the original detection lever 4 moves out of the position where the original detection photosensor 8 is shut off, the drive motor 5 is driven again to push up the original table. The lever 7 is rotated in the direction of the arrow b in FIG. 1 to push up the document stacking plate 2 to keep the uppermost position of the document S substantially constant.

The operation of pushing up the original stacking plate 2 will be described with reference to FIG. FIG. 5 is a detailed view showing a locus of pushing up the document table pushing-up lever 7 as a cam, and the large diameter portion 7b serves as a pressure receiving portion in contact with the lower surface of the document stacking plate 2.

In FIG. 5, when the original stacking plate 2 is at the lowermost position, the protrusion 7a of the original plate pushing-up lever 7 is at the position 7a-L, and when the original stacking plate 2 is at the uppermost position, the original plate pushing-up lever 7 is moved. The protrusion 7a is located at the position 7a-H. Further, the document table pushing-up lever 7 is located near the top dead center when the document stacking plate 2 is at the uppermost position.

This top dead center means a position where the increase / decrease (the amount of elevation) of the large-diameter portion 7b which comes into contact with the lower surface of the original stacking plate 2 becomes substantially zero even when the original table pushing-up lever 7 is rotated. It means that there is.

The rotation locus of the document table pushing-up lever 7 is as shown in FIG. 5, and in FIG. 5, the rotation angle of the document table pushing-up lever 7 is α1 = α2 = α3 = α4. On the other hand, looking at the amount of movement of the original stacking plate 2 that has been pushed up, H1>H2>H3> H4.

That is, even if the number of rotations of the drive motor 5 is constant, the amount by which the document stacking plate 2 is pushed up by the platen pushing-up lever 7 becomes smaller as the document stacking plate 2 is pushed up from the lowermost position to the uppermost position. The document stacking plate 2 is supported in the vicinity of the position where the amount of ascent and descent is 0 when the document is closest.

Therefore, although the load applied to the platen pushing-up lever 7 changes depending on the remaining amount of the documents S on the document stacking plate 2, the document stacking plate 2 having a large load of the documents S having a large load is near the lowermost position. When the document stacking plate 2 having a smaller load of the document S is near the uppermost position, the amount of pushing up the document stacking plate 2 is smaller than that in the case where the document S is loaded regardless of the inertia of the drive motor 5. The accuracy of the stop position of the stacking plate 2 can be improved and the uppermost position of the document S can be maintained within a certain range, and the contact pressure between the feeding roller 3 and the sheet material S is stable and good feeding is possible. I do.

Next, in particular, the continuous sheet feeding mode in which the apparatus itself separates and feeds a large number of originals S stacked on the original stacking plate 2 one by one, and the operator sets one by one on the original stacking plate 2. Regarding the case where the manual sheet feeding mode for stacking and feeding the originals S is performed with the same original sheet stacking plate 2, FIG. 1 will be described as a continuous sheet feeding mode, and FIG. 2 will be described as a manual sheet feeding mode.

The continuous paper feeding mode is the same as the above-mentioned feeding operation. In the manual feed mode, the drive motor 5 is driven by the feeding operation start signal, the output shaft 6 connected to the drive motor 5 rotates, and the output gear 9 configured substantially integrally with the output shaft 6 is shown in FIG. Rotate in the direction of arrow d. Then, the friction gear 11 meshing with the output gear 9 rotates in the direction of arrow e in FIG. 2, and the document table pushing-up shaft 10 and the document table pushing-up lever 7 also rotate in the same direction via the above-described transmission force restricting means, and the document is pushed. The loading plate 2 is pushed up to the highest position (the position shown in FIG. 2).

Then, the operator sets one original S to be fed on the original stacking plate 2. Then, the document detection lever 4
By rotating the document set on the fulcrum 4a as the center and shutting off the document detection photosensor 8, the feeding roller 3 rotates in the direction of arrow g, and the document is fed in the direction of arrow A.

Here, in the manual feed mode, the original stacking plate 2 is pushed up to the uppermost position (the state shown in FIG. 2).
Since the document is set on the document stacking plate 2, the operator may forcibly apply a biasing force in the direction in which the document stacking plate 2 is pushed down.

However, as shown in FIG. 2, when the document stacking plate 2 is at the uppermost position, the platen pushing-up lever 7 is at the top dead center, and the urging force (pressure receiving direction) for pushing down the document stacking plate 2 is , In the direction of arrow F, that is, from the large diameter portion 7b of the document table pushing lever 7 toward the document table pushing shaft 10 serving as a cam shaft, the urging force applied to the document table pushing shaft 10 rotates from the large diameter portion 7b. Since it is transmitted to the platen pushing-up shaft 10 without a moment, the platen pushing-up lever 7 does not rotate.

Therefore, with the configuration of the document stacking plate 2 and the document table pushing-up lever 7 as described above, the operator can load the document stacking plate 2
Is at the uppermost position, the original stacking plate 2 does not descend from the uppermost position even if the original stacking plate 2 is forced down.

Further, when an urging force is applied when the document stacking plate 2 is located at a position other than the uppermost position, an excessive load is applied to the document table pushing-up lever 1 and the drive motor 5 by the friction transmission means described above. Is prevented and damage is prevented.

(Second Embodiment) FIG. 6 shows a second embodiment to which the present invention is applied. The first embodiment uses a link mechanism in addition to the configuration using the cam-shaped push-up lever 7.

In this link mechanism, an upper link 30 as two link members and a lower link 31 as a lever member are flexibly connected by a pin 32, and the lower link 3
A lower end portion 31a of the document No. 1 is connected to a drive motor (not shown) and is rotated to raise and lower the document stacking plate 2. Further, the upper end portion 30a of the upper link 30 has the original stacking plate 2
Are connected rotatably.

As shown in the figure, when the lower link 31 rotates by the same angle α1, α2, α3, α4, H1, H2,
The upper end portion 30a of the upper link 30 moves by the moving amount of H3 and H4. This amount of movement is the amount of movement of the document stacking plate 2, and as is clear from the figure, the amount of movement decreases as the amount of movement increases with respect to the same rotation angle of the lower link 31.

Further, when the document stacking plate 2 is at the uppermost position, the link mechanism becomes the top dead center, and even if the document stacking plate 2 is forcibly pushed down and the pressing force of the arrow A2 is applied, the link mechanism is rotated. Without this, the original stacking plate 2 does not descend from the uppermost position.

[0077]

According to the present invention described above, the relative positional relationship between the sheet material stacking means and the feeding means is reduced so that the sheet material is reduced and the load applied to the driving means is reduced. Even if the driving amount increases due to the inertia of the driving unit, the vertical movement amount of the sheet material stacking unit is small, so that the accuracy of the stop position of the sheet material stacking unit is improved. Therefore, the contact state with the feeding means for feeding the sheet material is maintained within a certain range, and stable feeding can be performed.

In the stopped state of the sheet material stacking means in which the lifting amount of the lifting means is 0, the sheet material stacking means is prevented from descending, and the sheet feeding means is used even when the operator manually feeds the sheet material. The contact state of is stable and the sheet material can be reliably fed.

A cam means, a link means or the like can be adopted as the elevating means, and the accuracy of the stop position of the sheet material stacking means and the sheet material in the state of the top dead center where the ascending / descending amount of each means becomes 0 The position holding characteristic of the loading means is improved.

In the drive control means provided with the transmission force regulating means, when an excessive load is applied when the sheet material stacking means is located at a position other than the uppermost position, the transmission force regulating means causes the elevating means and the drive control means. No excessive load is applied to and damage is prevented.

[Brief description of drawings]

FIG. 1 is an explanatory cross-sectional view of a sheet material feeding device of the present invention.

FIG. 2 is an explanatory cross-sectional view of the sheet material feeding device of the present invention.

FIG. 3 is a diagram of a transmission force regulating means.

FIG. 4 is a diagram of an image reading apparatus including a sheet material feeding device to which the present invention is applied.

FIG. 5 is a diagram illustrating an operation of a document table pushing-up lever pushing up a document stacking plate.

FIG. 6 is a diagram of a second embodiment in which a platen push-up lever is used as a link mechanism.

FIG. 7 is a cross-sectional explanatory view of a conventional sheet material feeding device.

FIG. 8 is a cross-sectional explanatory view of a conventional sheet material feeding device.

[Explanation of symbols]

 1 Feed Tray 2 Document Loading Plate (Sheet Material Loading Means) 2a Support Point 2b Cutout 3 Feed Roller (Feeding Means) 4 Document Detection Lever (Sheet Material Position Detecting Means) 4a Support Point 5 Drive Motor (Drive Control Means) 6 Output shaft 7 Original plate push-up lever (elevating means / cam means) 7a Projection 7b Large diameter part 8 Original detection photosensor 9 Output gear 10 Original plate push-up shaft 11 Friction gear 11a Locking part 12 Stopper 12a Uppermost position regulating slope 12b Maximum Lower position regulation slope 13 Friction member 14 Holding member 15 Spring 16 Feed roller support member 16a Support point 20 Feed roller 21 Separation roller 22, 23, 24, 25, 26 Roller pair 27 Ejection section 28a, 28b Illumination means 29a, 29b Reading means M1 friction transmission mechanism (transmission force regulation means) R reading section S original (sheet material)

Claims (12)

[Claims] 1. A sheet material stacking means for stacking sheet material, a feeding means for contacting and feeding the sheet material on the sheet material stacking means, and an elevating means for supporting the sheet material stacking means in a vertically movable manner. And a drive control means for driving the elevating means and a sheet material position detecting means for detecting the uppermost position of the sheet material stacked on the sheet material stacking means. In a sheet material feeding device that adjusts the relative positional relationship between the sheet material stacking means and the feeding means by the drive control means according to the position, the elevating means has a relative positional relationship between the sheet material stacking means and the feeding means. As the sheet material stacking means becomes smaller with respect to the driving amount input by the drive control means of the ascending / descending means, and is supported near the position where the ascending / descending amount becomes 0 when the sheet material stacking means comes closest. Sheet feeding apparatus characterized by setting the so that. 2. A sheet material stacking means for stacking sheet material, a feeding means for contacting and feeding the sheet material on the sheet material stacking means, and an elevating means for raising and lowering while supporting the sheet material stacking means. And a drive control means for driving the elevating means and a sheet material position detecting means for detecting the uppermost position of the sheet material stacked on the sheet material stacking means. In a sheet material feeding device that adjusts the relative positional relationship between the sheet material stacking means and the feeding means by the drive control means according to the position, the elevating means has a relative positional relationship between the sheet material stacking means and the feeding means. The sheet material stacking means can be stopped in the vicinity of a position where the vertical movement amount of the sheet material stacking means with respect to the drive amount input by the drive control means of the lifting means becomes 0 as That the sheet feeding apparatus. 3. A continuous sheet feeding mode in which a plurality of sheet materials stacked on the sheet material stacking means are separated and fed one by one, and the sheet material stacking means is placed on the sheet material stacking means at a stop position where the lifting amount is 0. 3. The sheet material feeding device according to claim 2, further comprising a manual paper feed mode in which sheet materials are stacked and fed one by one. 4. The elevating means includes a cam means having a contour curve for supporting the sheet material stacking means, and a large diameter portion of the contour curve of the cam means when the sheet material stacking means is 0 when the ascending / descending amount is zero. Is a pressure receiving portion for receiving a force for supporting the sheet material stacking means, and the pressure receiving direction thereof is substantially coincident with the direction connecting the large diameter portion and the cam shaft. The sheet material feeding device according to item 1. 5. The elevating means includes a link mechanism having a lever member that is connected to the drive control means and rotates, and a link member that connects the lever member and the sheet material stacking means, and the link mechanism has the elevating amount. When the sheet material stacking means is 0, the lever member and the link member are aligned in a straight line, and the pressure receiving direction from the sheet material stacking means is substantially the same as the aligned direction. The sheet material feeding device according to any one of claims 1 to 3, characterized in that. 6. The drive control means is provided with a transmission force regulation means for regulating transmission of an excessive force inputted from the sheet material stacking means via the elevating means. The sheet material feeding device according to any one of 1. 7. The seat according to claim 6, wherein the transmission force regulation means is provided with a friction transmission mechanism that regulates the transmission force to a predetermined magnitude by the friction generated between the two closely contacting members. Material feeding device. 8. The feeding means is configured to be movable so as to come into contact with the sheet material placed on the sheet material stacking means in response to a change in the uppermost position of the sheet material. Item 6. The sheet material feeder according to any one of items 1 to 5. 9. The sheet material position detecting means also functions as a sheet material presence / absence detecting means for detecting the uppermost position of the sheet material and for detecting the presence / absence of the sheet material placed on the sheet material stacking means. The sheet material feeding device according to claim 3. 10. In the manual feed mode, when the sheet material position detecting means detects the sheet material with the sheet material stacking means stopped at the uppermost position, the feeding of the sheet material is started. The sheet material feeding device according to claim 9. 11. A sheet material feeding device according to claim 1, and an image forming means for forming an image on a sheet material conveyed to the sheet material feeding device. An image forming apparatus characterized by. 12. A sheet material feeding device according to claim 1, and an image reading means for reading image information of a sheet-shaped document conveyed to the sheet material feeding device. An image reading device characterized by the above.