JPS6330252B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a copy paper feeding device for an electrostatic copying machine, and more particularly to a paper feeding cassette in which copy papers of predetermined sizes are stacked and stored. The present invention relates to a paper feeding device for a copying machine, which is detachably attached to the body of the copying machine and is configured to sequentially feed the uppermost copy sheets one by one by a paper feed roller pivotally supported on the body.

BACKGROUND ART In a conventional paper feeding device for a copying machine, a removable paper feeding cassette is provided on the machine body, and this paper feeding cassette is installed at least in the paper feeding direction of a loading plate on which copy sheets are placed in a stacked state. The upstream side or the downstream side can be moved up and down, and a push-up means is provided for urging the board upward by a spring force when the paper feed cassette is attached to the machine body. As a result, the uppermost surface of the copy paper comes into contact with a paper feed roller provided in the machine body, and the uppermost copy paper is fed one by one as the paper feed roller rotates.

Problems to be Solved by the Invention In the prior art described above, the spring force of the push-up means causes the loading plate to be displaced upward as copy paper is consumed, and the push-up force decreases accordingly. Therefore, there are problems in that a plurality of sheets of copy paper are fed at the same time, and that the copy paper is deviated from the paper feeding direction, causing diagonal feeding.

Another prior art that solves this problem as much as possible is shown in FIG.
has been disclosed. In a paper feed cassette that is removably attached to the body of a copying machine, copy paper 302 is loaded on a mounting plate 304 that can be angularly displaced, and the mounting plate 304 is formed with a protrusion 304a that projects downward. .
A shaft 318 is provided in the body of the copying machine, and this shaft 3
A push-up lever 305 is fixed to 18. The contact portion 305a of the push-up lever 305 is connected to the protrusion 304.
a. The shaft 318, and therefore the push-up lever 305, is biased by a spring in a counterclockwise direction in FIG. 10 about the axis of the shaft 318.

When the stack height of the copy sheets 302 on the loading plate 304 is large, the contact portion 305a of the push-up lever 305 and the protrusion 30 as shown by the solid line in FIG.
4a and the axis of the shaft 318 is small, so the push-up lever 305
can increase the force that pushes up the mounting plate 304 upward in FIG. Therefore, copy paper 302
The contact pressure P between the uppermost surface of the paper feed roller 301 and the paper feed roller 301 can be set to an optimal value.

When the copy paper 302 is consumed by copying and its stack height becomes smaller, the state shown by the imaginary line in FIG.
The distance R2 between the abutting position of 05a and the protrusion 304a of the mounting plate 4 and the axis of the shaft 318 is a large value, so that the push-up lever 305
The force pushing up 04 becomes smaller. Therefore, the pressure P between the paper feed roller 301 and the top surface of the copy paper with a small stack height, which is shown by the imaginary line, is
2 can be kept almost constant regardless of the stacking height. Thereby, copy sheets 302 can be reliably fed one by one from the paper feed cassette.

In the prior art shown in FIG. 10,
Even if the amount of copy paper 302 stored in the paper feed cassette changes, the top surface of the copy paper and the paper feed roller 30
Although there is an advantage in that the pressure applied to the copy sheet can be kept approximately constant, such an advantage is only achieved when the size of the copy sheet is constant. When copy sheets of various sizes are selected and used, the weight of the copy sheets varies depending on the size. Therefore, in the prior art shown in FIG. 10, when copy sheets of different sizes are used, it is not possible to maintain a constant pressing force between the uppermost surface of the copy paper and the paper feed roller.

The purpose of the present invention is to solve the above-mentioned technical problems,
The pressure contact force between the top surface of copy paper of various sizes and a paper feed roller is kept as constant as possible, thereby ensuring that copy paper can be fed one by one from a paper feed cassette. An object of the present invention is to provide a paper feeding device for a copying machine.

Means for Solving the Problems The present invention includes a plurality of paper feed cassettes 8, 272, each paper feed cassette 8, 272 individually stores copy paper of different sizes, and the paper feed cassettes 8,272 is the bottom 222a and this bottom 222
Place the stacked copy paper on top of a,
A loading plate 224 capable of angularly displacing at least the upstream side or the downstream side of the copy paper in the paper feeding direction around an axis perpendicular to the paper feeding direction, and a pair of locks that abut on both sides of the leading edge of the top surface of the copy paper. The paper feed cassettes 8, 272 are removably attached to the body of the copying machine, and a paper feed roller 58 is pivotally supported on the machine body at a fixed position above the paper feed cassettes 8, 272. A push-up member 256 inserted through the opening 226 formed in the bottom 222a is provided on the machine body so as to be angularly displaceable about an axis perpendicular to the paper feeding direction, and this push-up member 256 is angularly displaceable about the axis of rotation. In a paper feeding device of a copying machine in which the loading plate 224 is elastically pushed up all the time to rotate elastically in a direction in which the uppermost surface comes into contact with the paper feeding roller 58, the loading of the pushing up member 256 It has a contact portion 256a at a position where it contacts the board 224, and the lower surface of the mounting board 224 is provided with projections 240, 278 that contact the contact portion 256a of the push-up member 256. The protruding lengths l1 and l3 are selected depending on the size of the copy paper to be loaded, respectively.
The contact portion 256a has an upwardly convex curved surface in a plane perpendicular to the axis of the push-up member 256.
Contact position 40 between 56a and protrusions 240, 278
2, 404, the contact position 402, 404 becomes closer to the rotation axis 4 of the push-up member 256.
This is a paper feeding device for a copying machine characterized by having a shape that is further away from 03.

Effect According to the present invention, by forming a curved protrusion convex on the paper feed roller side on the push-up member,
This prevents multiple sheets of copy paper from being fed at the same time, and prevents the copy paper from being deviated from the paper feeding direction and causing diagonal feeding, thus ensuring that copy paper is fed one sheet at a time from the paper feed cassette. becomes possible.

Embodiment An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a partially cutaway perspective view of a transfer type electrostatic copying machine according to an embodiment of the present invention. Transfer-type electrostatic copying machines basically use a movable part that is part of an optical device, including an exposure lamp, that moves back and forth in order to form an image corresponding to the original onto the photosensitive layer of a photosensitive drum. An electrostatic image corresponding to the original is formed on the photosensitive layer,
It has a machine that develops an electrostatic image using a two-component developer consisting of a carrier and toner, transfers this toner image onto copy paper, and heats and fixes it. A transparent plate 4 on which a document is placed horizontally is provided at the top of the body 2 of the copying machine. The body 2 is provided with a document holding plate 6 for pressing the document onto the transparent plate 4. A paper feed cassette 8 for storing copy paper is detachably attached to the right end of the machine body 2 as shown in FIG. This paper feed cassette 8 can be pulled out from the machine body 2 to the right in FIG. After copying is completed, the copy paper is discharged onto a copy tray 10 provided at the left end of the machine body 2 in FIG. The number of consecutive copies of each document is set by a copy number setting button 12 provided at the upper front of the machine body 2. In the copying operation, after turning on the main switch 14, the number of copies is set using the number of copies setting button 12, and then the print button 16 is pressed.
The amount of exposure of the original image by the optical device onto the photosensitive layer 24 of the photosensitive drum 26, which will be described later, is determined by the exposure amount adjustment knob 18.
Adjusted by. Further, the toner supply amount adjustment knob 20 can be adjusted according to the degree of darkness of the original, and the mixing ratio of toner and carrier can be manually adjusted to a predetermined value.

FIG. 2 is a simplified vertical sectional view of the copying machine shown in FIG. 1, viewed from the front. A photosensitive drum 26 consisting of a cylindrical base body 22 and a photosensitive layer 24 provided on the entire circumferential surface is rotatably mounted approximately in the center of the body 2.
, a charging corona discharger 30 charges the photosensitive layer 24, visualizes the electrostatic latent image formed on the photosensitive layer 24, and converts it into a toner image, which remains on the photosensitive layer 24 after transfer. A conventional developing device 32 is equipped with a cleaning function to remove toner, a transfer corona discharger 34 is used to transfer the toner image formed on the photosensitive layer 24 to transfer paper, and a photosensitive device is used after the transfer process. A corona discharger 36 for static elimination to remove residual charges remaining on the layer 24
and a static elimination lamp 38.

An optical device 40 is provided above the photosensitive drum 26 to radiate an image of the document onto the photosensitive layer 24 between the charging corona discharger 30 and the developing device 32, as shown in the second figure. In this optical device 40,
Light projecting means 42 for projecting light onto the original through transparent plate 4 includes a photosensitive lamp 44 and a reflecting mirror 46 . The light projected onto the document from the light projecting means 42 and reflected is transmitted to the photosensitive layer 20 through a movable reflecting mirror 50, a lens 52 having an in-mirror, and a reflecting mirror 54.
The image of the document is projected onto the photosensitive layer 24, and an electrostatic image is formed on the photosensitive layer 24.

The copy sheets stacked and stored in the paper feed cassette 8 are fed from the paper feed cassette 8 by the paper feed roller 58 along the copy paper conveyance path 56 shown by the broken line. 60, 61 and the guide plate 62, a pair of feed conveyance rollers 64,
65 so as to be brought into close contact with the photosensitive layer 24 of the photosensitive drum 26 facing the transfer corona discharger 34. After the transfer is completed, one end of the copy paper in the width direction is held between a peeling roller 66 and a conveyance roller 68, and the copy paper is peeled off from the photosensitive layer 24 and transferred to the guide plate 7.
0 and then sent to a heat fixing device 72, where the toner image on the copy paper is heat fixed. The copy paper after being heated and fixed is transported by a pair of transport rollers 74, 75 and a guide plate 76.
Then, it is discharged onto the copy tray 10 via a pair of discharge rollers 78 and 79.

A cooling blower 80 is provided inside the aircraft body 2 . This cooling blower 80 sucks air from outside and blows it below the transparent plate 4. The transparent plate 4 is cooled by this air. Air is exhausted from the outlet 84.

3 is a perspective view of the vicinity of the paper feed cassette 8 when the paper feed cassette 8 is installed in the copying machine, FIG. 4 is a plan view of the paper feed cassette 8 shown in FIG. FIG. 3 is a cross-sectional view taken along line V-V. Paper cassette 8
consists of a rectangular box body 222 with an open top surface, and accommodates JIS B row size copy paper.
A mounting plate 224 is provided in the front half of the bottom 222a of the box body 222. Note that this mounting plate 224 is omitted in FIG. 3 for the sake of simplification. A copy paper push-up lever receiving opening 226 is formed at the front end of the bottom 222a of the box body 222.
Fitting lever receiving recesses 228 are formed at the front ends of the left and right side plates 222b and 222c of the box body 222, respectively. A locking pawl 230 is provided at the upper end of both corners of the box body 222, including the front side plate 222d and left and right side plates 222b, 222c, respectively, so as to be movable in the vertical direction or fixedly.
comes into contact with the top surface of the copy paper due to its own weight. Furthermore, wedge-shaped notches 232 are formed at the upper edges of both side plates 222b and 222c, respectively. A pair of stop plates 238 are provided on the front and rear side plates 234 and 236 of the machine body 2, and the notch 232 of the paper feed cassette 8 is engaged with the stop plates 238.

Both side plates 222 are provided on the lower surface of the front end of the boarding plate 224.
A protrusion 240 extending back and forth (up and down in FIG. 4) is provided at the center position between b and 222c, that is, at the center position in the width direction of the copy paper. This protrusion 240 is the fifth
In the illustrated state, facing the opening 226, the mounting plate 224
It protrudes from the bottom surface by a length l1. Boarding board 2
On the lower surface of the rear end of 24, both side plates 222b, 222
A support protrusion 242 that protrudes toward the bottom 222a of the box body 222 is provided at the center position between the width directions of the copy paper. A pair of fitting pieces 244 are further provided at the rear end of the mounting plate 224. The fitting piece 244 extends downwardly from the rear end of the mounting plate 224, and its tip is bent rearward. This fitting piece 244 is attached to the bottom 22 of the box body 222.
They are respectively fitted into fitting holes 246 formed in 2a.

The front side plate 234 and the rear side plate 236 contain copy sheets of JIS B row size stored in the paper feed cassette 8 and other paper feed cassettes 272 (to be described later).
A plurality of paper feed rollers 5 (three in the figure) are arranged as shown in Fig. 4 to correspond to JIS A column size copy paper.
A shaft 248 to which 8 is fixed is pivoted. axis 248
A sprocket wheel 148 is fixedly attached to the sprocket wheel 148, and an electromagnetic clutch 146 is further attached to the sprocket wheel 148.
The shaft 248 is rotationally driven in the direction of arrow 252 by the action of the electromagnetic clutch 146, as will be described later.
As a result, only one of the uppermost copy sheets stored in the paper feed cassette 8 is supplied to the copy paper transport path 56.

In front of the paper feed cassette 8, the side plates 234, 236
A shaft 254 is pivotally fixed to. A push-up lever 256 is rotatably mounted on the shaft 254 at a position corresponding to the opening 226 of the paper feed cassette 8. One end of a coil spring 258 is fixed to the shaft 254, and the other end of the coil spring 258 is fixed to the push-up lever 256. The coil spring 258 moves the push-up lever 256 toward the arrow 26.
0, that is, the mounting plate 224 is elastically biased upward. The contact portion 256a of the push-up lever 256 contacts the protrusion 240 of the mounting plate 224.

The contact portion 256a is arranged in a plane perpendicular to the axis of the push-up lever 256, that is, the axis of the shaft 254 (i.e., the rotation axis indicated by reference numeral 403 in FIG. 9, which will be described later) (FIGS. 6 and 7, which will be described later). 9) has an upwardly convex curved surface. A pair of fitting levers 262 are fixed to the shaft 254 at an interval corresponding to the width of the paper feed cassette 8. The fitting lever 262 is fitted into the recess 228 of the paper feed cassette 8.

A substantially fan-shaped positioning member 264 is fixed to one end of the shaft 254 (this side in FIG. 3). Side plate 2
A stop pin 266 is fixed to 34 in proximity to an arcuate portion 264a formed at one end of the positioning member 264. Stop pin 266 and positioning member 26
A tension spring 26 is provided between the other end 264a of the
8 is installed. A pair of protrusions 2 that are engaged with the stop pins 266 are provided at both circumferential ends of the arcuate portion 264a.
64c and 264d are formed.

FIG. 6 is a front view of FIG. 3 with the side plate 234 omitted. Referring to FIGS. 2 and 6, a receiving member 270 for receiving the paper feed cassette 8 is provided at the right end of the machine body 2 in FIG. Receiving member 270
A cassette guide part 270a extends inwardly into the machine body 2 while being inclined downward at a predetermined angle and guides the bottom surface of the paper feed cassette 8;
A contact portion 270b is bent from the front end of the paper feed cassette 8 and extends upward, and the front end of the paper feed cassette 8 comes into contact with the contact portion 270b; a copy paper guide section 27 that guides copy paper fed from the copy paper to the copy paper transport path 56;
0c. Note that the copy paper guide portion 270c in FIGS. 6 and 7 is omitted in FIG. The cassette guide section 270a includes a mounting plate 22.
An opening (not shown) is formed corresponding to the opening 226 of the paper feed cassette 8 so that the projection 240 of the paper feed cassette 8 can come into contact with the push-up lever 256.

To attach the paper feed cassette 8 to the machine body 2, first insert the bottom of the paper feed cassette 8 along the cassette guide portion 270a of the receiving member 270 until the front side plate 222d of the paper feed cassette 8 abuts the contact portion 270b. and bring it into the state shown in Figure 6. At this time, the shaft 254
is one protrusion 264c of the positioning member 264
is in a pivoted position in which it engages locking pin 266. In this state, the shaft 254 is biased clockwise in FIG. 6 by the spring force of the tension spring 268.
The fitting lever 262 fits into the recess 228 of the paper feed cassette 8.
It fits into and holds it in place. Therefore, the contact portion 256a of the push-up lever 256 contacts the protrusion 240, and is locked in the state shown in FIG.

Next, the paper feed cassette 8 is moved to the seventh position in the direction in which the leading end of the paper feed cassette 8 moves upward, using the rear end of the cassette guide portion 270a of the receiving member 270 as a fulcrum.
Rotate as shown in the diagram. Then, the notch 232 of the paper feed cassette 8 is engaged with the stop plate 238,
The rotation of the paper feed cassette 8 is stopped, and the paper feed cassette 8 is prevented from moving rearward (to the left in FIG. 7). By rotating the paper feed cassette 8, the shaft 254 and the positioning member 26 are rotated.
4 is rotated counterclockwise in FIG. 7, the tension spring 268 passes through the most extended state, and is biased counterclockwise by the spring force of the tension spring 268. Therefore, the positioning member 264
is rotated to a position where the other protrusion 264d engages with the stop pin 266.

By rotating the shaft 254 counterclockwise, the push-up lever 256 is unlocked. Therefore, the push-up lever 256 is rotated counterclockwise in FIG. 7 by the spring force of the coil spring 258, and pushes up the protrusion 240 of the mounting plate 224. Therefore, the front end of the mounting plate 224 is tilted and pushed up using the support protrusion 242 as a fulcrum as shown in FIG. Then, the uppermost surface of the copy paper stacked on the copy paper mounting plate 224 is pressed against the paper feed roller 58. Further, both leading edge corners of the top stacked copy paper come into contact with the locking pawl 230 . When the paper feed roller 58 is rotationally driven in this state, the uppermost copy paper is sent forward along the copy paper guide portion 270c of the receiving member 270, and is supplied to the copy paper conveyance path 56. The length l2 (see FIG. 4) of the mounting plate 224 is determined by the rotation of the push-up lever 256.
It is preferable to choose it long enough so that it is pushed up substantially parallel. By doing so, the angle of the uppermost copy sheet with respect to the locking pawl 230 is prevented from changing due to a change in the stacked thickness of the copy sheets on the mounting plate 224, and therefore the uppermost copy sheet is prevented from changing its angle with respect to the locking pawl 230. To ensure that only one copy sheet of the higher rank is sent out.

The pressing force of the copy paper against each of the left and right paper feed rollers 58 is adjusted to be substantially constant by a support protrusion 242 provided on the mounting plate 224. That is, by the push-up operation of the push-up lever 256, the mounting plate 224 is
Assuming that the pressing force on the paper feed roller 58 is not constant when the paper feed roller 58 is pushed upward, the support protrusion 242 is provided at the center between the side plates 222b and 222c, so the mounting plate 224 The support protrusion 242 is used as a fulcrum to tilt toward the side with a larger pressing force. Balance is achieved at a position where the pressing force on each paper feed roller 58 is equal. Therefore, regardless of the quality, quantity, etc. of the copy paper, the pressing force on each paper feed roller 58 is kept constant, and a single copy paper is reliably fed.

To take out the paper cassette 8 from the machine body 2 after all of the copy paper in the paper cassette 8 has been consumed, the paper cassette 8 is rotated from the state shown in FIG. 7 to the state shown in FIG. Then, the notch 232 of the paper feed cassette 8 is removed from the stop plate 238, and at the same time, the fitting lever 262 and therefore the shaft 254 are rotated clockwise in FIG. Therefore, the shaft 254 is returned to the rotational position shown in FIG. 6, where one protrusion 264c of the positioning member 264 engages with the stop pin 266. Further, as described above, when the fitting lever 262 rotates, the front plate 222 of the paper feed cassette 8
d, the copy paper push-up lever 256 is rotated clockwise and returned to the position shown in FIG. In this state, the paper feed cassette 8 is moved rearward (to the right in FIG. 6) and taken out.

The contact portion 256a of the push-up lever 256 has an upwardly convex arcuate cross section parallel to a vertical plane along the copy paper conveying direction. As a result, when the amount of loaded copy paper decreases and the push-up lever 256 rotates in the direction of the arrow 260, the push-up lever 256 rotates in the direction of the arrow 260, and when the push-up force by the spring 258 is small, compared to a flat case without a convex arcuate surface. This allows the uppermost copy sheet to contact the paper feed roller 58 with appropriate pressure, thereby making it possible to reliably feed each copy sheet one by one. Furthermore, when a large amount of copy paper is loaded, the spring force of the spring 258 is increased so that the uppermost copy paper can contact the paper feed roller 58 with appropriate pressure for feeding a single sheet. .

By pasting a flocked sheet piece 286 only directly under the leftmost paper feed roller 58 in FIG. 4 on the loading plate 224, an appropriate frictional force is applied to the copy paper, thereby making it easier to stack the copy paper. Even when the quantity is small, copy sheets can be fed one by one.

FIG. 8 is a perspective view of another paper feed cassette 272. The paper feed cassette 272 stores copy paper of JIS A column size, which is smaller in width than JIS B column size. The paper feed cassette 272 is similar to the paper feed cassette 8.
It consists of a box 274 of the same size as the box 222. A partition plate 276 is provided at a position from the side plate 274b of the box body 274 corresponding to the width l4 of the JIS A-copy paper size. The mounting plate, which is omitted in FIG. 8, is accommodated between the side plate 274b and the partition plate 276. Similar to the above-mentioned mounting plate 224, this mounting plate is provided with a protrusion 278 (see FIG. 5) that contacts the contact portion 256a, a fitting lever receiving recess 280, a locking pawl 282, etc. . The fitting piece of the mounting plate is fitted into the fitting hole 284 formed in the bottom plate recess 274a of the box body 274 in the same manner as described above.

The protrusion 278 is provided protrudingly at an intermediate position between the side plate 274b and the partition plate 276. Projection length of projection 278
l3 is shorter than the protrusion length l1 of the protrusion 240 of the paper feed cassette 8 mentioned above. Therefore, the paper feed cassette 272
When the relatively small JIS A-copy paper stored in the paper feed cassette 8 is pushed up by the push-up lever 256, the pressing force on the paper feed roller 58 is equal to the relative This is smaller than the pressing force on the paper feed roller 58 of JIS B row size copy paper, which is relatively large. Therefore, it is small in size and light in weight.
JIS A column size copy paper and large and therefore heavy copy paper can contact the paper feed roller 58 with the optimum pressure for feeding a single sheet.

The contact portion 256a of the push-up lever 256 and the protrusions 240, 2 provided on the lower surface of the mounting plate 224
Referring to FIG. 9, the operation caused by contact with 78 is as follows.
I will explain further. In the paper feed cassette 8 for storing large-sized copy paper, a protrusion 240 provided on the lower surface of the mounting plate 224 projects downward by a length l1. When the amount of large-sized copy paper accumulated in the paper feed cassette 8 is large, the contact position 402 between the contact portion 256a of the push-up lever 256 and the protrusion 240 and the push-up lever 25
The distance between the axis of rotation 403 and the axis of rotation 403 of the shaft 254 on which 6 is supported is indicated by reference numeral l4, and at this time the top surface of the copy paper is in contact with the paper feed roller 58 with optimal pressure. .

In the paper feed cassette 272 in which small-sized copy paper is stored, a protrusion 278 is provided on the lower surface of the mounting plate 224 and protrudes by a length l3 (l1>l3), which is shorter than the length l1.
will be provided. At this time, the protrusion 278 has the contact portion 256a of the push-up lever 256 at the contact position 404.
contact with. The distance l5 between the rotation axis 403 of the shaft 254 and the contact position 404 is longer than the aforementioned distance l4 (l4<l5).

Push up lever 256 by coil spring 258
9 around the shaft 254 in the counterclockwise direction in FIG. 9 is approximately constant regardless of the angle of the push-up lever 256. Therefore, when large-sized copy paper is stored in the paper feed cassette 8, the push-up lever 256 contacts the protrusion 240 at the contact position 402, and the distance l4 between the rotation axis 403 and the contact position 402 is The push-up lever 256 is short, so the push-up lever 256 pushes up the protrusion 244, and therefore the mounting plate 224, upward in FIG. 9 with a large force. The paper feed cassette 8 carries copy paper having a large size, and therefore has a large weight. Therefore, the contact pressure between the uppermost surface of the copy paper stored in the paper feed cassette 8 and the paper feed roller 58 can be set to an optimum value.

When using the paper feed cassette 272 that stores small-sized copy paper, the protrusion 27
8 and the contact portion 256a of the push-up lever 256 contact at the contact position 404, and the rotation axis 403
The distance l5 between the contact position 404 and the push-up lever 25 is larger than the distance l4 as described above.
6 by the protrusion 278 and therefore the mounting plate 224
The force pushing it upward in FIG. 9 is small. The size of the copy paper stored in the paper feed cassette 272 is small, and therefore its weight is small. Therefore, the contact pressure between the top surface of the copy paper in the paper feed cassette 272 and the paper feed roller 58 is approximately the same value as when the cassette 8 containing large-sized copy paper is used. In this way, the contact pressure between the uppermost surface of the copy paper and the paper feed roller 58 is maintained at an optimum value regardless of the size of the copy paper.

As a large size copy paper is stored in the paper feed cassette 8 and the copy paper is consumed in the copying operation, the weight of the copy paper on the loading plate 224 decreases. Along with this, the push-up lever 256 is angularly displaced in the counterclockwise direction in FIG. 9 around the rotation axis 403 of the shaft 254. According to this angular displacement of the push-up lever 256 in the counterclockwise direction, the contact portion 256a of the push-up lever 256
The contact position 402 between the projection 240 and the rotation axis 4
As it moves further away from 03, the distance l4 becomes longer. As a result, the force exerted by the push-up lever 256 to push up the protrusion 240 upward in FIG. 9 is reduced. The top surface of the stacked copy paper, which is therefore consumed and lighter, contacts the feed roller 58 with optimum pressure. This also applies when the paper feed cassette 272 that stores small-sized copy paper is used.

The push-up lever 256 may be replaced with a push-up member having another structure.

Referring again to FIG. 3, with the paper feed cassette 8 containing JIS B row size copy paper positioned as shown in the figure, the side plate 222c of the paper feed cassette 8 is opened.
is pressing the actuator 418 of the detection switch 416 attached to the rear side plate 236. This detection switch 416 is in the cut-off state when the actuator 418 is pressed.

Therefore, with reference to FIG.
A through hole 420 is formed in c at a position facing the detection switch 416 when the paper feed cassette 272 is attached to the machine body 2. Therefore, the actuator 418 of the detection switch 416 is not pressed and is therefore in a conductive state.

As described above, the detection switch 416 is in the cutoff state for the paper feed cassette 8 that accommodates JIS B row size copy paper, and is in the conductive state for the paper feed cassette 272 that accommodates JIS A row size copy paper. Therefore, the detection switch 416 detects the width of the copy paper.

Effects As described above, according to the present invention, the push-up member 25
The abutting portion 256a formed at 6 has an upwardly convex curved surface in a plane perpendicular to the axis of the push-up member 256 (the plane of the paper in FIG. 9).
and a protrusion 2 provided on the lower surface of the mounting plate 224.
40, 278 is shaped such that as it moves upward, the abutting position becomes further away from the rotation axis 403 of the push-up member 256, and the protrusion 24
The downward protruding lengths l1 and l3 of 5,278 correspond to the paper feed cassette 8 in which large-sized copy paper is stored.
Since the paper feed cassette 272, which stores small-sized copy paper, is selected to have a large size and a small paper feed cassette 272, the contact pressure between the top surface of the copy paper and the paper feed roller 58 is reduced regardless of the size of the copy paper. This makes it possible to maintain a constant optimum value in the receiver, thereby preventing multiple sheets of copy paper from being fed at the same time and copy paper being misaligned with respect to the paper feeding direction and causing skewed feeding. This allows copy sheets to be reliably fed one by one from the paper feed cassette.

[Brief explanation of the drawing]

Fig. 1 is an overall perspective view with a part cut away of an embodiment of the present invention, Fig. 2 is a simplified vertical sectional view of the copying machine shown in Fig. Perspective view showing the state in which the paper feed cassette 8 is installed, No. 4
3 is a plan view of FIG. 3, FIG. 5 is a view taken along the line V-V of FIG. 4, FIG. 6 is a front view of the vicinity of the paper feed cassette 8 of FIG. 8 is a perspective view of another cassette 272, and FIG. 9 is a front view of the vicinity of the paper feed cassette in another operating state.
A simplified sectional view for explaining the operation due to contact with 78, and FIG. 10 is a sectional view of the prior art. 2... Aircraft, 8,272... Paper feed cassette, 1
4... Main switch, 16... Print button, 58... Paper feed roller, 224... Mounting plate, 2
30,282...Latching claw, 234,236...Side plate, 240,278...Protrusion, 244...Fitting piece, 246...Fitting hole, 256...Pushing lever, 258...Coil spring.

Claims (1)

[Scope of Claims] 1. A plurality of paper feed cassettes 8, 272 are provided, each paper feed cassette 8, 272 individually stores copy paper of different sizes, and the paper feed cassettes 8,
272 has a bottom 222a and stacked copy sheets placed on the bottom 222a, and rotates at least the upstream or downstream side of the copy sheets in the paper feeding direction around an axis perpendicular to the paper feeding direction. It has a mounting plate 224 that can be angularly displaced, and a pair of locking claws 230 and 282 that abut on both sides of the leading edge of the uppermost surface of the copy paper,
The paper feed cassette 8,272 is removably attached to the body of the copying machine, and the paper feed cassette 8,272 is attached to the body of the copying machine.
A paper feed roller 58 is pivotally supported at a fixed position above, and a push-up member 256, which is inserted through an opening 226 formed in the bottom 222a, is provided on the machine body so as to be angularly displaceable around an axis perpendicular to the paper feeding direction. Raising member 256
is angularly displaced around its axis of rotation and the mounting plate 22
4 is constantly pushed up elastically to feed the top surface of the paper feed roller 5.
8, the copying machine has a contact portion 256a at a position where the push-up member 256 contacts the mounting plate 224; The lower surface is provided with protrusions 240, 278 that abut against the contact portion 256a of the push-up member 256, and the downwardly projecting lengths l1, l3 of these protrusions 240, 278 are the lengths of the copy paper to be loaded. The protrusions 240 and 278 are selected to be large or small depending on the size, respectively, and the protrusions 240 and 278 have a pair of locking claws 23.
The abutment part 256a has an upwardly convex curved surface in a plane perpendicular to the axis of the push-up member 256, and the abutment part 256a
Contact position 40 between 56a and protrusions 240, 278
2, 404, the contact position 402, 404 becomes closer to the rotation axis 4 of the push-up member 256.
1. A paper feed device for a copying machine, characterized in that it has a shape that is further away from 03.