JP2002046870A - Sheet feeding device and picture image formation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To properly regulate paper feeding pressure to use a push-up spring without breaking it even when the paper feeding pressure is non-standardized and to reduce separation failure such as jamming, overlapped feeding, etc. SOLUTION: It is possible to increase the paper feeding pressure by increasing elasticity by contracting length of the push-up spring 208 by setting an end part of the push-up spring 208 selectively on this step part 220 by providing the push-up spring 208 between a bottom surface of a sheet storage cassette 201 and a middle plate 207 and providing the step part 220 on a mounting part of this push-up spring 208. Consequently, it is possible to regulate pushing-up force of the push-up spring 208.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet feeding apparatus for feeding sheets such as recording paper and originals to image processing means such as image forming means and original reading means, and an image forming apparatus using the same. It is.

[0002]

2. Description of the Related Art Generally, image forming apparatuses such as printers and copying machines are provided with a sheet feeding device for separating and feeding sheets (recording paper) one by one. In recent years, as image forming apparatuses such as printers and copiers have been increased in speed and color, it has been required to feed various kinds of media without jams (paper jams) or double feed. As a result, there is a need for a more reliable sheet feeding device.

In this sheet feeding apparatus, various sheets are stored.
A separation method for separating sheets one by one is used. For example, there is a printer provided with two separation units having different separation methods in order to enhance the sheet separation performance. In one example of this method, both ends of the sheet in the width direction are regulated by a width regulating plate, and the trailing end of the sheet is regulated by a trailing edge regulating plate. Separation with a claw, and a feed roller (rotated in the sheet feeding direction) and a retard roller, which are the second separation means
(Rotation in the direction opposite to the sheet feeding direction), which is separated and fed by a so-called retard roller separation method.

A conventional sheet feeding device will be described with reference to FIGS. 6 is a cross-sectional view of a main configuration of the sheet feeding device, FIG. 7 is a schematic plan view of a sheet storage cassette, FIG. 8 is a cross-sectional view of a mounting position of a push-up spring, and FIG. FIG. 8B shows a cross section, and FIG. 8B shows a BB cross section of FIG.

[0005] An intermediate plate 207 pushed up by a push-up spring 208 made of a coil spring is installed in the sheet storage cassette 201, and sheets S are stacked on the intermediate plate 207. The lower end of the push-up spring 208 is bent toward the center, and the bent positioning portion 208a is
The rotation is stopped by being fitted into a slit 201b provided at the push-up spring mounting position on the bottom surface of the housing 201a, and the inside of the push-up spring 208 is fitted into a rib 201d provided on the bottom surface of the sheet storage cassette 201. The positioning of the push-up spring 208 is achieved.

[0006] A flange 207a is formed at a portion of the middle plate 207 where the push-up spring 208 is attached, and the push-up spring 208 is fitted and positioned.

The middle plate 207 is pushed up by a push-up spring 208 as the sheet S decreases. The uppermost sheet of the sheets S stacked on the middle plate 207 is in contact with the separation claw 205 that regulates the height of the leading end. The separating claw 205 is also used for separating sheets one by one as described later. Thus, the height position on the leading end side of the uppermost sheet is always kept at the same height level. Further, a rear end regulating plate 210 is arranged on the upstream side in the feeding direction, and a width regulating plate (not shown) for regulating the width direction is arranged in the sheet width direction, and the sheet S is placed at a predetermined position. To store.

A pickup roller 202 having a semicircular shape with a part of the outer periphery cut away is disposed on the main body side of the apparatus. When the surface pushes the middle plate 207 through the sheet S, the push-up spring 208 is pressed.
Is compressed to generate a paper feed pressure. The pickup roller 202 having a relatively large friction coefficient forcibly sends out the uppermost sheet by this sheet feeding pressure.

Since the sheet S in the lower layer than the uppermost sheet S has a small friction between the sheets, only the uppermost sheet S is sent out, and the lower layer sheet S stays in the sheet storage cassette 201 due to the resistance of the separation claw 205. In this manner, the fed sheet S is supplied to the separation claw 205 serving as the first separation unit.
As a result, the uppermost sheet S is separated into one sheet and fed.

If the separation function of the separation claw 205 is not achieved, the uppermost sheet is separated and fed by the separation roller pair 211 as the second separation means. The separation roller pair 211 includes a feed roller 203 that rotates in a sheet feeding direction, and a retard roller that is provided so as to be able to press against the feed roller 203 and rotates in a direction opposite to the sheet feeding direction. Only the upper sheets are separated and sent out one by one.

[0011]

In the above-described sheet feeding apparatus, the pickup roller 202 is driven by the push-up spring 2.
When the sheet feed pressure received by the step S08 is too high, the sheet pushing force of the pickup roller 202 becomes large.
Even though the friction between the sheets S is small, a plurality of sheets are detached from the separation claw 205 at a time and double feed is likely to occur. On the other hand, if the sheet feeding pressure is too small, the force for feeding out the sheet is small even though the friction coefficient of the pickup roller 202 is high. Etc. leading to poor paper feeding.

For this reason, it is necessary to set an optimum sheet feeding pressure for separating the sheets. Conventionally, the sheet feeding pressure of the sheet feeding apparatus is measured when the sheets are fully loaded and when the sheets are loaded little. For non-standard ones, discard the push-up springs 208 (three), install another push-up spring, re-measure,
It is performed until the standard is satisfied.

[0013] Then, even if it is out of the standard of several tens of grams, all the push-up springs (three) are discarded and replaced, and there is a problem that the yield is poor and the cost is increased.

The separating means is not limited to the separating claw,
A similar problem arises when other separation means such as a separation pad is used because the paper feed pressure needs to be adjusted appropriately.

The present invention has been made in order to solve the above-mentioned problem, and it is possible to appropriately adjust the paper feeding pressure, to use the push-up spring without discarding even if the measured value is out of standard, thereby increasing the cost. The purpose is to prevent.

[0016]

In order to achieve the above-mentioned object, the present invention provides a sheet stacking means for stacking sheets and capable of moving up and down, a push-up spring for pushing up the sheet stacking means, A sheet feeding means for feeding out the sheets stacked on the sheet stacking means, and urges the sheet stacking means toward the sheet feeding means by the push-up spring, so that an uppermost one of the stacked sheets is In a sheet feeding device which is brought into pressure contact with the sheet feeding means and feeds a sheet by the sheet feeding means, a pressing force adjusting means for changing a force for pushing up the sheet stacking means by changing a mounting phase of the push-up spring. It is characterized by having.

[0017] In the present invention, the pressing force adjusting means may be provided with a step at a mounting portion of the push-up spring, and selectively attach the end of the push-up spring to a mounting position having a different height of the step to change a phase. The elastic force is adjusted by changing the amount of deflection of the spring by setting.

According to the present invention, the pressing force adjusting means is provided with three or more steps having different heights, and selectively attaches the end of the push-up spring to a mounting position where the height of the step is different to change the phase. By setting, the elastic force of the push-up spring is adjusted in a plurality of stages.

According to the present invention, the push-up spring is a coil spring, and is set at an attachment position at a different height of the step by rotating around a center line to change an attachment phase, thereby adjusting an elastic force. It is characterized by.

In the present invention, the sheet stacking means is an intermediate plate supported swingably on a housing of the sheet storage cassette, and the push-up spring is disposed between a bottom surface of the housing and the intermediate plate. It is characterized by having been done.

The present invention is characterized in that the push-up spring is disposed between the bottom surface of the housing and the middle plate, and the step is provided at a mounting portion of the bottom surface for attaching the push-up spring.

According to the present invention, the push-up spring is disposed between the bottom surface of the housing and the middle plate, and the step is provided at a mounting portion of the middle plate to which the push-up spring is attached.

The present invention is characterized in that a plurality of the push-up springs and the pressing force adjusting means are arranged in parallel so that the elastic force of each push-up spring can be adjusted.

The present invention is characterized in that a separating claw is disposed at a corner of the leading end of the sheets stacked on the sheet stacking means and separates sheets fed by the sheet feeding means one by one. And

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) A first embodiment of the present invention will be described with reference to FIGS. 1 is a schematic plan view of the sheet storage cassette, FIG. 2 is a cross-sectional view of a mounting position of the push-up spring to the sheet storage cassette ((a) a standard mounting position, and (b) a state where the push-up spring is set at a 180 ° rotation position. FIG.
The same components as those described in the related art are denoted by the same reference numerals, and detailed description will be omitted.

The housing 201a of the sheet storage cassette 201
At the bottom surface, a mounting portion for supporting the lower end side of the push-up spring 208 is formed in a concave shape, and is provided between the middle plate 207 and the mounting portion as sheet stacking means which is swingably supported by the housing 201a. , A push-up spring 208 is disposed. The three push-up springs 208 are arranged in a direction perpendicular to the sheet feeding direction. A step is provided at each of the three mounting portions of the push-up spring 208 as a pressing force adjusting means. This step is constituted by a step 220 provided in the mounting portion.

In the standard mounting position shown in FIG. 2A, the lower end of the push-up spring 208 is bent toward the center as in the prior art, and the bent positioning portion 208a is bent. The rotation of the sheet storage cassette 201 is prevented by being fitted into a slit 201b provided in a mounting portion on the bottom surface of the sheet storage cassette 201. At a position 180 degrees out of phase with the standard mounting position, a slit 201c for stopping rotation is provided in the step 220 having a high height. In this manner, a step having a different height direction between the standard mounting position and the 180 ° rotation position is provided, and the elastic force is adjusted by selectively changing the setting position of the positioning portion 208a of the push-up spring 208. It constitutes a pressing force adjusting means.

With this configuration, when the paper feed pressure to the pickup roller 202 is lower than the standard, the push-up spring 208 is rotated around its center line C as shown in FIG. By rotating the mounting phase by 180 °, the positioning portion 208a of the push-up spring 208 is set in the slit 201c on the higher step side. As a result, the push-up spring 208 contracts to increase the elastic force, and the middle plate 2
The push-up force of 07 goes up. This makes it possible to increase the pressure contact force between the sheet stacked on the middle plate 207 and the sheet feeding roller 202.

At this time, the pressing force may be adjusted by changing the phases of all three push-up springs 208, or may be adjusted with only one or two springs. Just do it. By doing so, the sheet feeding pressure increases, and the push-up spring can be used without being discarded, and the standard can be satisfied.

Further, even when the elastic force of the push-up spring 208 is reduced by use, the paper feeding pressure can be increased and maintained at an optimum value by changing the phase of the push-up spring 208, thereby extending the life of the apparatus. You can also.

Push-up spring 208 in the present embodiment
Are three, but the same applies to the case where the number of used is two or one. Also, the sheet pressure may be adjusted stepwise by providing a plurality of steps having different heights at positions having different phases, instead of providing one step.

Further, in the above-described embodiment, the step 220 is provided so that the mounting position at the 180 ° rotation position is higher, but a step is provided between the standard mounting position and the 180 ° rotation position. Any configuration may be used as long as the standard mounting position side is recessed downward, for example.

Next, an image forming apparatus in which the sheet storage cassette 201 is mounted will be schematically described. In addition,
Here, a schematic configuration will be described along the flow of the sheet.

The sheets S stacked and stored in the sheet storage cassette 201 are sent out by a pickup roller 202 which rotates counterclockwise in the figure, and a separation claw 205 as a first separation means and a second separation means Only the uppermost sheet S is separated and fed by the retard roller separation method including the feed roller 203 and the retard roller 204. Next, a laser beam corresponding to the image information is irradiated on the photoconductor 102 rotating in the clockwise direction by the laser scanner 101, and an electrostatic latent image is formed on the photoconductor 102. This electrostatic latent image is developed with toner in a developing unit (not shown).

The sheet S fed and fed by the pair of transport rollers 103 and 104 is transferred to a fixing unit 106 by transferring an image as an unfixed image in an image forming unit 105. The fixing device 106 is provided with a heater unit. The heater unit generates heat when AC power is supplied thereto, and is pressurized to a predetermined pressure by a pressing roller, whereby the conveyed sheet S is undecided. Fix the received image.

The sheet S, which has passed through the fixing means 106 and has been subjected to the fixing process, is conveyed by a conveying roller pair 107 and is face-up tray 108 on which the image surface is stacked or face-down which is stacked with the image surface down. Tray 1
09.

(Second Embodiment) A second embodiment will be described with reference to FIGS. FIG. 3 is a schematic plan view of the sheet storage cassette, and FIG. 4 is a cross-sectional view of the mounting position of the push-up spring to the middle plate ((a) standard mounting position;
(B) 180 ° rotational position), which is the same as the configuration described in the section of the related art and the configuration described in the first embodiment. Is omitted. The description of the overall configuration and functions of the image forming apparatus is also the same as that of the first embodiment, and therefore will not be repeated, and the features of the present invention will be described in detail.

The structure of this embodiment is similar to that of the intermediate plate 207.
Is provided on the side of the push-up spring mounting portion, which constitutes a step as a pressing force adjusting means, so that the push-up spring 208
The height of the end can be adjusted. The stepped portion 230 is provided at a position 180 ° out of phase with the standard mounting position. The stepped portion 230 has a slit 207b for engaging with the positioning portion 208b of the push-up spring 208 and stopping rotation. Provided.

When the paper feed pressure to the pickup roller 202 is lower than the standard, as shown in FIG. 4B, the push-up spring 208 is rotated around the center line C to rotate the mounting phase by 180 ° and push up. A positioning portion 208b for stopping rotation of the spring 208 is set on the high side of the step portion 230. At this time, the positioning portion 208b is
The rotation of the push-up spring 208 is stopped by engaging with the lever 07c.

As a result, the push-up spring 208 contracts and the elastic force increases, and the push-up force of the middle plate 207 increases.
This makes it possible to increase the pressure contact force between the sheet stacked on the middle plate 207 and the paper feed roller 202. In this way, a step having a different height direction between the standard mounting position and the 180 ° rotation position is provided, and an additional force for adjusting the elastic force by selectively changing the set position of the end of the push-up spring 208 is provided. It constitutes pressure adjusting means.

As in the first embodiment, at this time, even if the phases of all three push-up springs are changed, only one or two push-up springs may be used, and the adjustment may be made to meet the standard value. By doing so, the sheet feeding pressure increases, and the push-up spring can be used without being discarded, and the standard can be satisfied.

The push-up spring in the present embodiment is
The number is three, but the same applies to two-type and one-type. In addition, the sheet pressure may be adjusted stepwise by providing a plurality of steps having different sizes at positions having different phases, instead of providing one step. For example, by providing a step having a different height at a position where the phase is shifted by 90 °, four-stage adjustment can be performed by rotating the push-up spring.

Further, in each of the above embodiments, the configuration has been described in which the elastic force of the push-up spring provided in the sheet storage cassette detachable from the image forming apparatus main body is adjusted. The present invention can be applied to a sheet feeding apparatus of a type in which sheets are stacked on a paper tray and fed out.

[0044]

According to the present invention, as described above, a step is provided at the mounting position of the push-up spring, and the feed pressure is changed by rotating the push-up spring to change the mounting phase. Is out of specification, change the paper feed pressure by simply changing the mounting phase of the push-up spring,
It can be used without discarding the push-up spring,
This has the effect of preventing an increase in cost.

[Brief description of the drawings]

FIG. 1 is a schematic plan view of a sheet storage cassette provided in a sheet feeding device according to a first embodiment.

FIG. 2 is a cross-sectional view of the sheet storage cassette taken along line BB at a position where the push-up spring of the sheet storage cassette shown in FIG.

FIG. 3 is a schematic plan view of a sheet storage cassette provided in a sheet feeding device according to a second embodiment.

FIG. 4 is a cross-sectional view of the sheet storage cassette shown in FIG.

FIG. 5 is a schematic sectional view of an image forming apparatus provided with a sheet feeding unit of the present invention.

FIG. 6 is a schematic sectional view of a conventional sheet feeding apparatus.

FIG. 7 is a schematic plan view of a conventional sheet storage cassette.

FIG. 8 is a cross-sectional view at a position where a conventional push-up spring is attached to a sheet storage cassette.

[Explanation of symbols]

 REFERENCE SIGNS LIST 101 laser scanner 102 photoreceptor 103 transport roller 104 transport roller 105 image forming unit 106 fixing means 107 transport roller 108 face-up tray 109 face-down tray 201 sheet storage cassette 201a housing 201b, c slit 202 pickup roller 203 feed roller 204 retard roller 205 Separation claw 207 Middle plate (sheet stacking means) 207b, 207c Slit 208 Push-up spring 208a Positioning portion 210 Rear end regulating plate 211 Separation roller pair 220 Step 230 Step

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3F343 FA02 FA03 FB01 GA03 GB01 GC01 GD01 HB03 HD18 JA01 JD11 KB03 LA04 LA15 LC06 LC07 LC19 LD04 MC11 MC12

Claims (10)

[Claims] 1. A sheet stacking means provided so as to be able to stack and move up and down a sheet, a push-up spring for pushing up the sheet stacking means, a sheet feeding means for feeding out the sheets stacked on the sheet stacking means, The push-up spring urges the sheet stacking means toward the sheet feeding means, and presses the highest stacked sheet against the sheet feeding means, and the sheet feeding means A sheet feeding apparatus for feeding a sheet, comprising: a pressure adjusting means for changing a mounting phase of the push-up spring to change a force for pushing up the sheet stacking means. 2. The pressurizing force adjusting means has a step at a mounting portion of the push-up spring, and selectively sets an end of the push-up spring at a mounting position having a different height of the step by changing a phase. The sheet feeding device according to claim 1, wherein the elastic force is adjusted by changing the amount of deflection of the spring. 3. The pressing force adjusting means is provided with three or more steps having different heights, and selectively sets the end of the push-up spring at a mounting position having a different step height by changing a mounting phase. 2. The sheet feeding device according to claim 1, wherein the elastic force of the push-up spring is adjusted in a plurality of steps. 4. The push-up spring is a coil spring,
The sheet feeding apparatus according to claim 2, wherein the elasticity is adjusted by rotating around a center line to change a mounting phase, thereby setting the step to a mounting position at a different height. . 5. The sheet stacking means is a middle plate swingably supported by a housing of a sheet storage cassette, and the push-up spring is disposed between a bottom surface of the housing and the middle plate. 5. The method according to claim 2, wherein
A sheet feeding device according to the item. 6. The push-up spring according to claim 5, wherein the push-up spring is disposed between a bottom surface of the housing and the middle plate, and the step is provided in a mounting portion of the bottom surface for the push-up spring. Sheet feeding device. 7. The push-up spring according to claim 5, wherein the push-up spring is disposed between a bottom surface of the casing and the middle plate, and the step is provided at a mounting portion of the push-up spring of the middle plate. The sheet feeding device as described in the above. 8. The sheet feeding device according to claim 1, wherein a plurality of said push-up springs and said pressing force adjusting means are arranged in parallel to adjust the elastic force of each push-up spring. Feeder. 9. A separating claw, which is arranged at a corner of the leading end of the sheets stacked on the sheet stacking means and separates the sheets fed by the sheet feeding means one by one. The sheet feeding device according to claim 1. 10. A sheet feeding device according to claim 1, further comprising: an image forming unit configured to form an image on a sheet fed from the sheet feeding device. Characteristic image forming apparatus.