JP2936496B2 - Paper feeder for image generator - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper feeding device for an image generating machine such as a laser beam printer or an electrostatic copying machine.

[Conventional technology]

2. Description of the Related Art An image generator, for example, a laser beam printer has been widely known (for example, see Japanese Patent Application Laid-Open No. 2-90177). An example of this type of laser beam printer will be described as a conventional technique.

An image forming unit is arranged above a central portion in the main body of the laser beam printer. The image forming unit includes an image carrier including a rotating drum and the like, a charging device arranged around the image carrier, a developing device, a cleaning device, and the like.

An optical unit is arranged above the image forming unit. The optical unit includes a laser light source, a rotating polygon mirror, a plurality of reflecting mirrors, a lens, and the like. The laser light source projects, for example, a laser beam based on image information output from a computer toward a rotating polygon mirror. The laser light reflected by the rotary polygon mirror is reflected by a plurality of reflecting mirrors, and is projected through a lens onto a projection area on the surface of the image carrier of the image forming unit.

At a position below the main body facing the transfer area of the image carrier,
A transfer device is provided. Furthermore, a copy paper transport path is formed below the image forming unit of the main body. The transfer area of the image carrier and the transfer device are positioned in the middle of the transport path.

A paper feeding device described later is provided upstream of the transport path. A fixing device including a fixing roller pair for fixing the toner image transferred to the copying machine is provided downstream of the conveying path, and the copy paper sent through the fixing roller pair is discharged to a receiving table via a discharge path. And a discharge roller pair.

When the operation of the laser beam printer is started, laser light is projected on the projection area of the image carrier, and the surface of the image carrier is
An electrostatic latent image corresponding to the image information is formed. Next, a toner image corresponding to the electrostatic latent image is formed by the developing device.
The toner image is transferred by a transfer device to a copy sheet fed by a sheet feeding device in a transfer area. The copy paper onto which the toner image has been transferred is sent to a fixing device, and after the toner image is fixed, the receiving paper is discharged to a table by a discharge roller pair.

Next, the paper feeding device in the conventional laser beam printer schematically described above will be described.

The paper feed device provided on the upstream side of the transport path includes a roller pair,
For example, it includes a separation roller pair for preventing double feeding of copy paper sent from a cassette by a paper feed roller. In this example, a curved conveyance path that guides the copy paper in the reverse direction is included on the upstream side of the conveyance path.

The separation roller pair is a forward rotation roller that is an inner roller disposed inside the curved conveyance path, and contacts the inner roller,
And a reversing roller, which is an outer roller disposed closer to the outside of the curved conveyance path.

When the operation of the laser beam printer is started, the separation roller pair arranged on the curved conveyance path starts rotating. Next, the paper feed roller rotates, and the copy paper is fed from the cassette to the separation roller pair. By the action of the separation roller pair, only the primary copy paper is guided along the curved conveyance path, and is sent to another roller pair provided downstream thereof, for example, a registration roller pair. This copy paper is sent to a transfer area of the image carrier by a pair of registration rollers.

[Problems to be solved by the invention]

Some of the laser beam printers described above are configured so that a standard envelope can be used as copy paper.
This is performed by mounting a cassette capable of storing a standard envelope.

In general, the standard envelope has a rectangular shape having a long vertical width and a short horizontal width with a length between the opposite sides in a plan view. The standard envelope generally refers to one whose size, that is, the vertical width and the horizontal width between the opposite sides are standardized according to a standard. An example of the width is 105 mm (in millimeters converted to inches) in the United States and 110 mm in the United Kingdom. When a standard envelope is used as copy paper,
It is set in the cassette so as to move in the vertical width direction.

In such a laser beam printer, as shown in FIG. 4, when the standard envelope P1 is sent to the separation roller pair by the paper feed roller as described above, the normal rotation roller 5 is not shown. The sheet is nipped by the reversing roller, and then only one standard envelope P1 is fed along the curved conveyance path 7.

Conventionally, the width (length in the axial direction) of the reversing roller 5
X is formed smaller than the horizontal width Y of the standard envelope P1. In addition, when the standard envelope P1 passes through the pair of separation rollers in the curved conveyance path 7, both ends of the standard envelope P1 have a width larger than the width of the normal rotation roller 5 because the standard envelope P1 is overlapped with a plurality of sheets. , Small "wrinkles" Z occur. When the wrinkles Z move in accordance with the movement of the standard envelope P1, a loud noise is continuously generated.

Thus, the noise of the laser beam printer, and more generally, the image generator, is increased, causing discomfort to the operator.

SUMMARY OF THE INVENTION Accordingly, it is a primary object of the present invention to provide a sheet feeding device for an image forming apparatus, which can prevent noise when a standard envelope is fed by a pair of rollers provided on a curved conveyance path.

[Means for solving the problem]

To achieve the above main object, according to one aspect of the present invention, there is provided a roller pair arranged on a curved conveyance path, for feeding a copy sheet fed by a paper feed roller to a downstream side of the curved conveyance path, The roller pair is, in a paper feeder of an image forming machine including an inner roller disposed inside the curved conveyance path and an outer roller disposed outside the curved conveyance path, wherein the width of the inner roller is The pair of rollers is set to have a length equal to or greater than the width of the standard envelope used as the copy paper, and the pair of rollers is a pair of separation rollers for preventing double feeding of the copy paper sent by the paper supply roller. The pair includes a forward roller and a reversing roller disposed in contact with the forward roller, the inner roller being the forward roller, the outer roller being the reverse roller, and the width of the reverse roller. Is set to a length equal to or less than the width of the standard envelope. That, the sheet feeding device of an image forming machine, characterized in that, is provided.

According to another aspect of the present invention, the apparatus is disposed on a curved conveyance path,
A roller pair for feeding the copy sheet sent by the paper feed roller to the downstream side of the curved conveyance path, the roller pair including an inner roller disposed inside the curved conveyance path, and an An outer roller disposed on the outer side, wherein the width of the inner roller is set to be equal to or greater than the width of a standard envelope used as the copy paper; Is set to be less than or equal to the width of standard-size sheet paper having a width longer than the width of the standard envelope used as the copy paper, and the roller pair includes a copy paper fed by the paper feed roller. A pair of separation rollers for preventing double feeding of the paper, the separation roller pair comprising a normal rotation roller and a reversing roller arranged in contact with the normal rotation roller, and the inner roller being the normal rotation roller. , The outer roller is the reversing roller, The width of the reversing roller is set to a length equal to or less than the width of the standard envelope.

[Action]

In the paper feeder configured according to one aspect and the other aspects of the present invention, the width of the inner roller is set to be equal to or greater than the width of the standard envelope used as the copy paper, so that it is the same as in the related art. In addition, the pulling action that has occurred between the position where the both ends of the inner roller contact each other and the both ends of the fixed envelope in the fixed envelope is eliminated. Therefore, when the standard envelope passes through the pair of rollers arranged in the curved conveyance path, the occurrence of fine wrinkles at both ends is prevented. Therefore, it is possible to prevent the generation of a loud noise that has conventionally occurred in association with the occurrence of wrinkles.

Further, the roller pair is a separation roller pair for preventing double feeding of the copy paper sent by the paper feed roller, and the separation roller pair includes a normal rotation roller and a reversing roller arranged in contact with the normal rotation roller. , The inner roller is a normal rotation roller, the outer roller is a reversing roller, and the width of the reversing roller is set to a length equal to or less than the width of the standard envelope, so that the standard envelope is disposed on the curved conveyance path. When passing through the separation roller pair
There is no direct contact between the forward roller and the reverse roller at both ends in the width direction. Accordingly, the reversing torque control function of the reversing roller is prevented from being impaired.

In the paper feeder configured according to another aspect of the present invention, the width of the inner roller is less than or equal to the width of a standard-size sheet of paper having a width longer than the width of a standard envelope used as copy paper. Therefore, when the sheet is nipped by the pair of rollers disposed in the curved conveyance path, the problem that the both corners at the leading end of the sheet are bent is eliminated. Therefore, the sheet paper does not cause any deformation when passing through the roller pair arranged on the curved conveyance path,
The original sheet shape is maintained.

〔Example〕

An embodiment in which the present invention is applied to a laser beam printer as an image generator will be described below with reference to FIGS.

FIG. 1 is a sectional view schematically showing a part of a laser beam printer provided with an embodiment of a sheet feeding device according to the present invention. The configuration and operation of the laser beam printer except for the paper feeding device according to the present invention are substantially the same as those of the conventional laser beam printer whose outline has been described above, and the description thereof is omitted here.

In FIG. 1, reference numeral 2 denotes a first cassette for storing copy paper, which is detachably attached to a position below an image forming unit (not shown) in the laser beam printer main body. In the first cassette 2, there is provided a first support plate 2a for lifting the stored copy paper upward.
A first paper feed roller 4 is disposed above the leading end of the first cassette 2. When the first support plate 2a is lifted by a known means, the stored copy paper comes into contact with the first paper feed roller 4.

Below the first cassette 2, a second cassette 6 for storing copy papers of different sizes is detachably mounted. In the second cassette 6, a second support plate 6a having the same function as described above is provided. A second paper feed roller 8 is located above the leading end of the second cassette 6.
Is arranged.

In this example, a standard envelope P1 (second
(See FIG. 3 and FIG. 3).
Further, in this example, the second cassette 6 is configured to store sheet paper P2 (see FIG. 2) having a standard size. The width D of the sheet paper P2 is selected in advance so as to have a width longer than at least the width of the standard envelope P1.

As described above, the copy paper transport path is formed below the image forming unit, and the first and second paper feed rollers 4 and 8 are provided.
Is located at the uppermost stream of the transport path. A first paper feed guide 4a and a second paper feed guide 8a are provided on the downstream side of the first and second paper feed rollers 4 and 8 in the transport path. In this example, a curved conveying path is formed by the reversing guide 9 in the conveying path at the downstream position of the first and second sheet feeding guides 4a and 8a. Along the reversing guide 9, a sheet feeding device 10 formed according to the present invention is provided.

The paper feeding device 10 is provided with the curved conveyance path, that is, the reversing guide 9.
And a roller pair 12 for feeding the copy paper sent by the first and second paper feed rollers 4 or 8 to the downstream side of the reversing guide 9. The roller pair 12 includes an inner roller 16 disposed inside the reversing guide 9, and an outer roller 18 which is in contact with the inner roller 16 and is disposed on the outer side of the reversing guide 9. The roller pair 12 is, in this example, the first
And a separation roller pair 12 for preventing double feeding of the copy paper fed by the second paper feed roller 4 or 8. The separation roller pair 12 is a forward rotation roller which is the inner roller 16.
16 and a reversing roller 18 which is an outer roller 18 arranged in contact with the normal rotation roller 16.

Another roller pair 14 is disposed downstream of the separation roller pair 12. In this example, the other roller pair 14 is constituted by a registration roller pair 14 for feeding the copy sheet sent via the separation roller pair 12 to a transfer area of an image carrier (not shown).

On the upstream side of the separation roller pair 12 in the transport path,
A double feed detection switch 11 for detecting double feed of copy paper is provided. A copy paper detection switch 13 for detecting the passage of the copy paper is provided on the downstream side of the separation roller pair 12, that is, at the position of the reversing guide 9.

Next, the roller pair 12 included in the paper feed position 10, that is, the separation roller pair 12, will be described with reference to FIG.

Forward roller 16 which is the inner roller 16 of the separation roller pair 12
, That is, the length A in the axial direction is set to be equal to or greater than the width B (A ≧ B) of the standard envelope P1.

The width A of the inner roller 16 is equal to or less than the width D of the sheet paper P2 having a width greater than the width B of the standard envelope P1 (A ≧
D). When a plurality of types are selected and used as the sheet paper P2, the relationship between the width A and the width D is as follows.
What is necessary is just to set it with the sheet paper P2 which has the minimum standard dimension.

Further, the width of the reversing roller 18 as the outer roller, that is, the length C in the axial direction is set to be equal to or less than the lateral width B of the standard envelope P1 (C ≦ B).

Next, the operation of the embodiment of the present invention configured as described above will be described with reference to FIGS.

When the operation of the laser beam printer is started, the normal rotation roller 16 starts rotating. At the same time, a reverse torque is applied to the reverse roller 18. After the rotation of the forward rotation roller 16, after a predetermined timing, for example, the first paper feed roller 4 starts to rotate according to the selection of the copy paper by the operator operated in advance. As a result, a plurality of fixed envelopes P1 are usually fed from the first cassette 2 to the separation roller pair 12 through the first paper feed guide 4a. These standard envelopes P1
However, when nipped by the normal rotation roller 16 and the reversing roller 18 of the separation roller 12, a torque limiter, which is a known reversing torque control unit, functions due to a change in the friction coefficient of the nip portion,
The reversing roller 18 reverses. As a result, double feeding of the standard envelope P1 is prevented, and only one standard envelope P1 is sent to the registration roller pair 14 through the reversing guide 9.

The standard envelope P1 sent to the registration roller pair 14 is blocked by the nip portion of the registration roller pair 14, and the slanted sheet is corrected by bending. Thereafter, the standard envelope P1 is engaged with the registration roller pair 14, and is sent to the transfer area of the image carrier.

The width A of the forward rotation roller 16 is equal to or larger than the width B of the standard envelope P1 (A
.Gtoreq.B), so that while the standard envelope P1 passes through the separation roller pair 12, the position where both ends of the normal rotation roller 16 contact the standard envelope P1 and the both ends of the standard envelope P1 The pulling action that occurred during the operation is eliminated. Therefore, when the standard envelope P1 passes through the separation roller pair 12 arranged on the reversing guide 9, the occurrence of fine wrinkles at both ends is prevented (see FIG. 3).

Further, since the width C of the reversing roller 18 as the outer roller is set to be equal to or larger than the width B of the standard envelope P1 (C ≦ B),
Separation roller pair 12 in which fixed envelope P1 is arranged on reversing guide 9
When passing through, the forward roller 16 and the reverse roller 18 do not directly contact at both ends in the width direction. Therefore, the reversing torque control function of the reversing roller 18 is prevented from being impaired.

On the other hand, when the sheet paper P2 is selected as the copy paper by the operator in advance, the second paper feed roller 8 starts rotating. As a result, a plurality of sheet papers P2 are normally fed from the second cassette 6 to the separation roller pair 12 through the second paper feed guide 8a. Subsequent conveyance operation of the sheet paper P2 is the same as described above, and thus the description is omitted.

In this case, since the width A of the normal rotation roller 16 is set to be equal to or less than the width D of the sheet paper P2 (A ≦ D), the sheet paper P2 is transferred to the separation roller pair 12 arranged on the reversing guide 9. When the nip is performed, there is no problem that both corners of the leading end of the sheet paper P2 are bent. Therefore, when the sheet paper P2 passes through the separation roller pair 12, no deformation occurs, and the sheet paper P2 is held in the original sheet shape stored in the cassette 6.

Note that other operations of the paper feeding device 10 are not directly related to the present invention, and thus description thereof is omitted.

〔The invention's effect〕

According to the sheet feeding device of the image generator according to the present invention described above based on the embodiments, the following effects can be obtained.

(1) Since the width of the inner roller is set to be equal to or greater than the width of the standard envelope used as the copy paper, when the standard envelope passes through a pair of rollers arranged in a curved conveyance path, both ends thereof are used. , The occurrence of fine "wrinkles" is prevented.

Therefore, the generation of loud noises, which has conventionally occurred, accompanying the occurrence of wrinkles is prevented, and a quiet image generator without noise can be obtained. As a result, no discomfort is given to the operator.

(2) When the width of the inner roller is set to be equal to or less than the width of a sheet of paper having a width greater than the width of the standard envelope, the sheet of paper is nipped by a pair of rollers arranged in a curved conveyance path. In this case, the problem that both corners of the leading end of the sheet paper are bent is eliminated.

Therefore, when the sheet paper passes through the pair of rollers arranged in the curved conveyance path, the sheet paper does not undergo any deformation and is kept in the original sheet shape.

(3) The roller pair disposed on the curved conveyance path is a separation roller pair, and the separation roller pair includes a normal rotation roller and a reversing roller disposed in contact with the normal rotation roller, and the inner roller is a normal rotation roller. When the outer roller is a reversing roller, and the width of the reversing roller is set to be equal to or greater than the width of the standard envelope, when the standard envelope passes through the separation roller pair arranged on the curved conveyance path, The forward and reverse rollers are
There is no direct contact at both ends in the width direction.

Accordingly, the reversing torque control function of the reversing roller is prevented from being impaired.

As mentioned above, although this invention was demonstrated in detail based on the Example, this invention is not limited to the said Example,
Various changes or modifications can be made within the scope of the present invention.

For example, the present invention has been described based on the embodiment applied to the laser beam printer, but is not limited to this. In addition, the present invention can be widely applied to any image generator to which the present invention can be applied, such as an electrostatic copying machine.

Further, the roller pair disposed in the curved conveyance path is not limited to the separation roller pair, but may be a roller pair including a driving roller and a driven roller.

[Brief description of the drawings]

FIG. 1 is a sectional view schematically showing a part of a laser beam printer provided with an embodiment of a sheet feeding device according to the present invention. FIG. 2 is a schematic diagram for explaining a size relationship between a separation roller pair and a copy sheet in FIG. 1; FIG. 3 is a schematic partial perspective view showing a state where a fixed envelope passes through the separation roller pair of FIG. 1; FIG. 4 is a partial perspective schematic view showing a state in which a standard envelope passes a conventional separation roller pair. 2 First cassette 4 First paper feed roller 6 Second cassette 8 Second paper feed roller 9 Curved transport path (reversing guide) 10 Paper feed device 12 … Roller pair (separation roller pair) 14… Registration roller pair 16… Inner roller (forward roller) 18… Outer roller (forward roller) P1… Standard envelope P2… Sheet paper A… Inner roller Width B: width of standard envelope C: width of outer roller D: width of sheet paper

Continuation of the front page (56) References JP-A-57-107342 (JP, A) JP-A-63-112333 (JP, A) JP-A-2-123043 (JP, A) JP-A-2-123048 (JP) , A) Japanese Utility Model 1-62231 (JP, U) (58) Fields surveyed (Int. Cl. ⁶ , DB name) B65H 1/00-3/68

Claims (2)

(57) [Claims] A roller pair disposed on the curved conveyance path for feeding the copy paper fed by the paper feed roller to a downstream side of the curved conveyance path, wherein the roller pair is provided inside the curved conveyance path. In a paper feeding device of an image forming machine, comprising an inner roller disposed and an outer roller disposed outside the curved conveyance path, the width of the inner roller is equal to or greater than the width of a standard envelope used as the copy paper. The pair of rollers is a pair of separation rollers for preventing double feeding of the copy paper sent by the sheet feeding roller, and the pair of separation rollers includes a forward rotation roller and the forward rotation roller. A reversing roller arranged in contact, the inner roller is the normal roller, the outer roller is the reversing roller, and the width of the reversing roller is less than the width of the standard envelope. The paper feed of the image generator, which is set apparatus. And a roller pair disposed on the curved conveyance path for feeding copy paper sent by a paper feed roller to a downstream side of the curved conveyance path, wherein the roller pair is provided inside the curved conveyance path. In a paper feeding device of an image forming machine, comprising an inner roller disposed and an outer roller disposed outside the curved conveyance path, the width of the inner roller is equal to or greater than the width of a standard envelope used as the copy paper. The width of the inner roller is set to be equal to or less than the width of a standard-size sheet of paper having a width longer than the width of the standard envelope used as the copy paper, and Is a pair of separation rollers for preventing double feeding of the copy paper sent by the paper feed roller, and the separation roller pair is composed of a normal rotation roller and a reversing roller arranged in contact with the normal rotation roller. Wherein the inner roller is the forward roller, Side roller is the reverse roller, the width of the reversing rollers is set to the width or less of the length of the constant-type envelopes, paper feeding device of an image forming machine, characterized in that.