JP2001240264A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily remove a jammed sheet by releasing the meshing of gears with a pair of feed rollers 10a and 10b when a sheet jamming occurs at the pair of feed rollers for sheets from a vertical multi-stage sheet feed cassette. SOLUTION: In a sheet feed unit U on an uppermost stage, a drive motor 29 is rotated in forward direction by a first gear transmission mechanism 25 so as to transmit a power to a gear 30 for a pair of feed rollers 10a through a motor pinion 30, gears 31 and 32, first sun gear 33, and a first planetary gear 34. When a sheet jamming occurs, the drive motor 29 is rotated reversely so as to separate a first planetary gear 34 revolving about the first sun gear 33 from the gear 36. The drive motor also reversely rotates a second planetary gear 45 meshed with a second sun gear 37 so as to interrupt the transmission of power to a second gear transmission mechanism 26 on a lower stage.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a printer, and more particularly, to turning on power transmission to a sheet feed cassette for stacking and supplying sheets in order to simplify paper jam processing. It relates to the configuration of the OFF switching mechanism.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus such as a copying machine of an electrostatic printing type or a printer, for example, Japanese Patent Laid-Open No.
In Japanese Patent Application Laid-Open No. 04437, etc., a paper cassette unit for storing cut paper (hereinafter simply referred to as paper) for each size for printing (recording) is arranged in multiple stages at a lower portion of a main body case of the apparatus. A gear mechanism provided with a power transmission disconnecting means for a paper feed roller provided for each unit is disposed corresponding to the unit, and these gear mechanisms are connected in series, and a drive provided in a main body case. The power from the motor is transmitted to the uppermost gear mechanism. When paper of a desired size is to be supplied, only the disconnecting means of that stage is turned ON and the disconnecting devices of the other stages are turned OFF, so that printing can be performed on paper of any size. There was something.

[0003]

However, in this type of multi-stage paper feed cassette, the plurality of gear mechanisms are meshed in series, so that when feeding paper from an appropriate stage paper feed cassette. When a paper jam occurs at the paper feed roller at the corresponding location or at the transport roller location in the paper transport path in the direction of the main body case, the operator can independently rotate these rollers at the location where the paper jam occurs. However, there is a problem that it takes time to remove the jammed paper.

The present invention solves the above-mentioned problems of the prior art, and can easily remove jammed paper with a simple structure by switching a transmission gear mechanism for each stage of a paper feed cassette to a free state. It is an object to provide an image forming apparatus.

[0005]

According to an aspect of the present invention, there is provided an image forming apparatus, comprising: an image forming unit for printing on a sheet; and a feeding unit for conveying the sheet to the image forming unit. A paper feed path, and a paper feed cassette for feeding paper toward the paper feed path is arranged so as to be detachable in upper and lower tiers, and a gear transmission mechanism corresponding to each of the feed cassettes Are vertically connected, and power is transmitted in series from an upstream side to a downstream side with respect to each of the gear transmission mechanisms from one drive motor, so that power is transmitted to at least a paper feed roller in each of the paper feed cassettes. In each of the image forming apparatuses, a first planetary gear mechanism for interrupting power transmission to a sheet feeding / conveying roller in a corresponding stage and a gear transmission on a downstream side are provided in each of the gear transmission mechanisms. A second planetary gear mechanism for interrupting power transmission to the structure, and when the one drive motor is rotated forward, power is transmitted to all gear transmission mechanisms and the paper feed roller, while the one drive motor is driven. When the motor is rotated in the reverse direction, the first and second planetary gear mechanisms are operated so that the transmission of power to all the gear transmission mechanisms and the sheet feed rollers is shut off.

On the other hand, an image forming apparatus according to a second aspect of the present invention includes an image forming section for printing on a sheet, and a sheet feeding path for conveying the sheet to the image forming section. The paper feed cassettes for feeding paper toward the path are arranged so that they can be pulled out in upper and lower multi-stages, and gear transmission mechanisms corresponding to the respective stages of the respective paper feed cassettes are vertically connected, and one drive An image forming apparatus configured to transmit power to at least a sheet feeding roller in each of the sheet cassettes by transmitting power in series from an upstream side to a downstream side with respect to each of the gear transmission mechanisms from a motor. In each of the gear transmission mechanisms, a first planetary gear mechanism for interrupting power transmission to a sheet feeding / conveying roller in a corresponding stage and a power transmission to a downstream gear transmission mechanism are interrupted. When the sheet cassette is moved in the pull-out direction at least between the first and second planetary gear mechanisms in the uppermost or any stage of the sheet cassette, the corresponding stage is provided. When the paper feed cassette is set in the paper feed state, the power transmission to the paper feed transport roller of the corresponding stage and the power transmission to the adjacent downstream gear transmission mechanism are simultaneously cut off. And an interlocking mechanism for operating the first and second planetary gear mechanisms in order to simultaneously achieve the power transmission of the first and second planetary gear mechanisms.

According to a third aspect of the present invention, there is provided the image forming apparatus according to the first or second aspect, wherein the first and second planetary gears in each of the sheet feed cassettes below the uppermost step and the lowermost step. When the paper cassette is moved in the pull-out direction between the mechanism and the mechanism, power transmission to the paper feed roller of the corresponding stage and power transmission to the adjacent downstream gear transmission mechanism are simultaneously shut off, When the paper cassette is set in the paper feeding state, the first and second power transmissions are simultaneously performed to the corresponding paper feed conveyance roller and the adjacent downstream gear transmission mechanism. It has an interlocking mechanism for operating the planetary gear mechanism.

Further, according to a fourth aspect of the present invention, in the image forming apparatus according to any one of the first to third aspects, the uppermost sheet cassette is provided in a main body case of the image forming apparatus. While a drive motor is arranged, the lower sheet cassette is configured to be additionally connected to a lower portion of the main body case.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described based on an embodiment in which a laser beam printer as an image forming apparatus is embodied. FIG. 1 is a schematic side sectional view of the printer 1, FIG. 2 is an enlarged perspective view of a main part of the sheet feeding device, with a partial cutaway, and FIG. 4 is a plan view showing a state where the spacer member is separated from one side edge of the sheet. As shown in FIG. 1, a printer 1 according to the present invention has a plurality of paper feed cassettes arranged in upper and lower stages. In the embodiment of FIG. 1, four paper feed units U1, U2, U3 and U4 are arranged in order from the top. A first paper feed cassette 3 is mounted on the first paper feed unit U1 which is opened forward at a lower portion in the main body case 2 so as to be able to be pulled out forward. Below this, an optional paper feed unit is arranged in a stacked manner as required, and each paper feed unit U2, U3, U
4 also open forward, and the second paper feed cassette 4, the third paper feed cassette 5, and the fourth paper feed cassette 6 are respectively mounted inside so as to be able to be pulled out forward.

Each of the paper feed cassettes 3 to 6 has a box shape with an open top, and each of the paper feed cassettes has an elastic spring (not shown) for elastically supporting a large number of sheets P stacked. A receiving plate 7 is provided. Each paper cassette 3-6
Is provided at the front end of the paper feed slot 8 as a transport path vertically penetrated, and the second paper feed unit U2 to the fourth paper feed unit U4 of each stage as an option are connected to the first paper feed unit. The paper P from the paper feed cassette disposed at the position where it is connected to the lower part of U1 is configured to be able to pass toward the upper transport path 5. In the main body case 2, a paper feed roller 9 a and a feed roller pair 10 a are arranged on the upper front side of the first paper feed cassette 3, and the second paper feed unit U 2 to the fourth paper feed unit U 4 below the paper feed roller 9 a are disposed. Are also the feed rollers 9b to 9d and the feed roller pair 10b to
10d is arranged so that the uppermost one of the stacked sheets P is turned one by one by each sheet feeding roller, and is conveyed to a long sheet feeding slot 8 as an upper conveying path via a pair of feed rollers. Is configured.

An image forming unit 12 including an image forming unit 13 and a fixing unit 14 is provided above the cassette storage unit 3.
Is separated by the paper feed rollers 9a to 9d, and then conveyed to the image forming unit 12 via a feed mechanism 17 having a plurality of feed roller pairs.

The image forming unit 13 includes a photosensitive drum 15, a transfer roller 16 pressed against the photosensitive drum 15, a toner cartridge unit 18, a charging device (not shown), and the like. Is transferred to the fixing unit 14 including the heating roller 19 and the pressing roller 20. The paper P for only one-sided printing on which an image is fixed on the paper surface by the fixing unit 14 is stacked on a paper discharge tray 23 on the upper surface of the printer main body 2 via a discharge conveyance path 21 and a plurality of roller pairs 22.
An operation panel (not shown) is provided on the upper front of the printer main body 2.
Is provided.

Next, the paper feed units U1 to U4 of the respective stages
The mechanism of power transmission of the paper feeding unit to the power supply will be described. The first gear transmission mechanism 25 in the first paper feed unit U1 is provided in the main body case 2. Also, the optional second
The second gear transmission mechanism 26 in the paper feeding unit U2,
The third gear transmission mechanism 27 in the sheet feeding unit U3,
As with the fourth gear transmission mechanism 28 in the sheet feeding unit U4, a gear transmission mechanism having the same configuration is disposed on one side of the case or the like for each stage corresponding to each sheet feeding unit. However, in FIG. 2, the first gear transmission mechanism 25 to the third gear transmission mechanism 2
7, the first gear transmission mechanism 25 and the second gear transmission mechanism 26 are shown in FIG.

In the first gear transmission mechanism 25, a drive motor 29 such as a stepping motor that can be rotated forward and backward is disposed in the main body case 2 to transmit the power to the motor pinion 30 and the first gear 31, and then the first gear 31 The power is transmitted from the second gear 32 rotating integrally with the first sun gear 33.
The first planetary gear 34 meshing with the first sun gear 33 is supported by a planetary arm 35 pivotally supported around a support shaft of the first sun gear 33, and the drive motor 2 that rotates forward
When the motor pinion 30 of FIG. 9 rotates clockwise in FIG. 2 (FIG. 3), the first sun gear 33 also rotates clockwise, and the first planetary gear 34 revolves clockwise while rotating in the counterclockwise direction. Therefore, the third gear 36 that rotates integrally with one of the feed roller pairs 10a, which is the transport roller pair,
The state where the first planetary gear 34 is engaged with the
The paper P can be transported in the direction (upward) of the feed mechanism 17.

On the other hand, the fourth small-diameter gear 3 which rotates clockwise integrally with the second sun gear 37 meshing with the second gear 32
8, a fifth gear 42, which is attached to the side surface of the paper feed roller 9a via three transmission gear groups (39, 40, 41) and rotates integrally, meshes to rotate clockwise in FIG. ing. Note that one of the transmission gear groups (39, 40, 41) is provided with a clutch cam 43, and the ON / OFF operation of an actuator 44 such as an electromagnetic solenoid causes the engagement claw 44a to rotate to supply power. The paper roller 9a is controlled so as to rotate intermittently every one rotation.

A second planet gear 45 meshing with the second sun gear 37 is supported by a planet arm 46 pivotally supported around a support shaft of the second sun gear 37, as shown in FIG. 2 (FIG. 3). )
And revolves in the counterclockwise direction while revolving clockwise, meshes with the first initial transmission gear 47 of the second gear transmission mechanism 26 in the lower stage (second paper feed unit U2), and further engages with the second initial transmission gear 48. Power transmission. Further, on the downstream side of the transmission, the second initial transmission gear 48 is connected to the first gear transmission mechanism 25.
Meshes with the first sun gear 33 of the same arrangement as in
Rotate this clockwise. The first planetary gear 34 meshing with the first sun gear 33 is supported by a planet arm 35 pivotally supported around a support shaft of the first sun gear 33, and the first planetary gear 34 is The first planetary gear 34 meshes with the third gear 36, which rotates clockwise integrally with one of the feed roller pairs 10b, which is the transport roller pair, because it revolves clockwise while rotating clockwise. Is held, and the sheet P can be conveyed in the direction of the vertically long slot 8 for sheet feeding in the upper first sheet feeding unit U1.

In the second gear transmission mechanism 26, the second sun gear 33 to the second sun gear 37 mesh with the first sun gear 33.
After the power is transmitted to the second sun gear 37, the fourth small-diameter gear 38 that rotates clockwise integrally with the second sun gear 37 through the three transmission gear groups (39, 40, 41) forms a side surface of the paper feed roller 9 b. The second planetary gear 4 meshes with the second sun gear 37 while the fifth gear 42, which is integrally mounted and rotates integrally with the second sun gear 37, is transmitted so as to rotate clockwise in FIG. 2 (FIG. 3).
Numeral 5 is supported by a planetary arm 46 pivotally supported around a support shaft of the second sun gear 37, and revolves clockwise in FIG. 2 (FIG. 3) while rotating in a counterclockwise direction. (Third paper feed unit U3) The power is serially transmitted to the lower stage such that it meshes with the first initial transmission gear 47 of the third gear transmission mechanism 27 in the third gear transmission mechanism 27 (hereinafter, the same structure as the second gear transmission mechanism 26). Because However, in FIG. 2, an actuator 44 such as an electromagnetic solenoid for the clutch cam 43 in the lower stage is not shown.

In this configuration, the first sheet feeding unit U
Paper P is stacked and stored for each size in the paper feed cassettes 3 to 6 of the first to fourth paper feed units U4, and a paper P of a desired size is designated by a command of an operation unit (not shown) and a print command is issued. Is issued, the drive motor 29 rotates forward. Then, by the operation of the actuator 44 for the sheet feeding unit of the designated stage, the sheet feeding roller can intermittently rotate only one rotation, but the sheet feeding rollers of the other stages are held in a non-rotating state. .

In this state, as described above, the feed roller pair 10a as the transport roller pair in the uppermost stage (the first paper feed unit U1) always meshes with the second planetary gear 34 in the first gear transmission mechanism 25. While the power is transmitted by
A lower second paper feed unit U2 via a second planetary gear 45;
The power is transmitted to the second gear transmission mechanism 26, the power is transmitted to the feed roller and feed roller pair 10b in that stage, and the power is transmitted to the lower third gear transmission mechanism 27 in the same manner. Power can be transmitted in series from the uppermost stage to the lower stage by the two drive motors 29.

If a paper jam occurs above the step being used, the leading end or halfway of the sheet P passing through the long slot 8 for feeding paper is fed to the pair of feed rollers 10a, 10a.
This means that the transfer operation is interrupted while being sandwiched by b, 10c and the like. In this case, the drive motor 29 is driven in reverse rotation. Then, as shown in FIG. 4, the motor pinion 30 in the first gear transmission mechanism 25 rotates counterclockwise, transmits the rotation to the first gear 31 meshing therewith, and then rotates integrally with the first gear 31. Power is transmitted from the second gear 32 to the first sun gear 33, and the first sun gear 3
Rotate 3 counterclockwise.

First planetary gear 3 meshing with first sun gear 33
4 is supported by a planetary arm 35 pivotally supported about a support shaft of the first sun gear 33, so that when the drive motor 29 rotates in the reverse direction, the first planetary gear 34 in FIG. Revolves counterclockwise while rotating in the clockwise direction, the first planetary gear 34 is provided on the side surface of one of the feed roller pairs 10a, which is a pair of transport rollers.
The gear 36 is disengaged. As a result, the feed roller pair 10a in the first paper feed unit U1 enters a free state. Further, after the second sun gear 37 receives power transmission from the second gear 32, the third transmission gear group (39, 39) includes a fourth small-diameter gear 38 that rotates counterclockwise integrally with the second sun gear 37. 40, 41), the fifth gear 42, which is attached to the side surface of the paper feed roller 9b or the like and rotates integrally, is gear-transmitted so as to rotate counterclockwise in FIG. 2 (FIG. 3). Second planetary gear 4 meshing with second sun gear 37
5 is supported by a planetary arm 46 pivotally supported so as to be rotatable around a support shaft of the second sun gear 37, and revolves clockwise while revolving counterclockwise in FIG. The first initial transmission gear 47 of the second gear transmission mechanism 26 in the paper unit U2) is disengaged (see the state of FIG. 4).

In this manner, the second planetary gear 45 in the uppermost stage and the first initial transmission gear 47 in the lower stage adjacent thereto are arranged.
, The transmission of power from the uppermost gear transmission mechanism 25 to the lower gear transmission mechanisms 26 and 27 (2) is interrupted.
Is in a free state, and the leading end or the middle of the sheet P passing through the long slot 8 for sheet feeding at each stage is set to the feed roller pair 10a, 1
The sheet P can be easily removed even if the sheet P is sandwiched between the sheets 0b and 10c.

FIGS. 5 to 7 show a second embodiment for clearing a paper jam. In this embodiment, the gear mesh release is executed in accordance with the movement of pulling out the sheet cassette in each stage. 5 and 6, only the uppermost first sheet feeding unit U1 and the lower second sheet feeding unit U2 adjacent thereto are shown, and the lower part thereof is not shown.

FIG. 5 shows a power transmission state (paper feeding state).
Drive motor 49 in first gear transmission mechanism 25 at the top
Can rotate only in the forward direction (operation in the paper transport direction), and the motor pinion 30 is meshed with the first gear 31. Next, power is transmitted from the second gear 32 rotating integrally with the first gear 31 to the first sun gear 33. This first
The first planetary gear 34 meshing with the sun gear 33 is a planetary arm 5 rotatably supported around a support shaft of the first sun gear 33.
When the motor pinion 30 of the drive motor 29, which is supported at 0 and rotates forward, rotates clockwise in FIG. 5, the first sun gear 33 also rotates clockwise, and the first planetary gear 34 rotates counterclockwise. Since it revolves in the clockwise direction while rotating, the state in which the first planetary gear 34 meshes with the third gear 36 that rotates integrally with one of the feed roller pairs 10a, which is a pair of transport rollers, is held, and the feed mechanism The sheet P can be transported in the direction of 17 (upward).

On the other hand, the fourth small-diameter gear 3 which rotates clockwise integrally with the second sun gear 37 meshing with the second gear 32
8, a fifth gear 42, which is attached to the side surface of the paper feed roller 9a via three transmission gear groups (39, 40, 41) and rotates integrally, meshes to rotate clockwise in FIG. ing. One of the transmission gear groups (39, 40, 41) is provided with a clutch cam (not shown) having the same configuration as that of the first embodiment, and turns ON / OFF an actuator 44 such as an electromagnetic solenoid. By operation, the engagement claw (not shown) is rotated, and the paper feed roller 9a is controlled so as to intermittently rotate every one rotation.

A second planetary gear 45 meshing with the second sun gear 37 is supported by a planetary arm 51 pivotally supported around a support shaft of the second sun gear 37, and is clockwise in FIG. And revolves in the counterclockwise direction while meshing with the first initial transmission gear 47 of the second gear transmission mechanism 26 in the lower stage (second paper feed unit U2), and further transmits power to the second initial transmission gear 48. . On the downstream side of the transmission, the second
The initial transmission gear 48 meshes with the first sun gear 33 of the same arrangement as in the first gear transmission mechanism 25, and rotates it in the clockwise direction. The first planetary gear 34 meshing with the first sun gear 33 is supported by a planet arm 50 pivotally supported around a support shaft of the first sun gear 33, and the first planetary gear 34 Since it revolves in the clockwise direction while rotating in the clockwise direction, the feed roller pair 10b as the transport roller pair
The state in which the first planetary gear 34 is engaged with the third gear 36 that rotates clockwise integrally with one of the rollers is held, and the paper P is fed vertically in the upper first paper feeding unit U1. It can be conveyed in the direction of the slot 8.

From the second gear 32 to the second sun gear 37 in the second gear transmission mechanism 26 meshing with the first sun gear 33.
After the power is transmitted to the second sun gear 37, the fourth small-diameter gear 38 that rotates clockwise integrally with the second sun gear 37 through the three transmission gear groups (39, 40, 41) forms a side surface of the paper feed roller 9 b. While the fifth gear 42 attached to and rotating integrally is gear-transmitted so as to rotate clockwise in FIG.
The second planetary gear 45 meshing with the second sun gear 37 is a second planetary gear 45.
It is supported by a planetary arm 46 pivotally supported so as to be rotatable around the support shaft of the sun gear 37, and revolves clockwise in FIG. 5 while rotating in a counterclockwise direction. The lower stage (third sheet feeding unit U3)
Meshes with the first initial transmission gear 47 of the third gear transmission mechanism 27 (hereinafter, the same structure as the second gear transmission mechanism 26).
Thus, power is transmitted to the lower stage in series.
The third paper feed unit U3 has the same configuration as the second paper feed unit U2.

Next, the first planetary gear 34 and the second planetary gear 4
An interlocking mechanism for releasing the meshing state of No. 5 will be described. First, arc-shaped partial gears 5 that rotate integrally with each other are provided on the base ends of the planetary arms 50 and 51.
2, 53 are formed. On the other hand, an interlocking body 56 on the inner surface of each paper feed unit U is formed with vertical rack portions 54 and 55 that mesh with the partial gears 52 and 53, respectively.
Are arranged to be able to move up and down. This substantially plate-shaped interlocking body 56
Is urged by the urging spring 57 in the downward moving direction.

The upper end of the interlocking body 56 is bent in the horizontal direction to form a contact portion 56a. One side of each of the sheet cassettes 3 to 6 slides on the lower surface of the contact portion 56a to push the interlocking body 56 against the force of the urging spring 57 when the respective sheet cassettes are pushed in. Then, a wedge-shaped pressing piece 58 that is pushed upward is fixed (see FIGS. 5, 6, and 7).

With the above configuration, when a print command is issued by designating a sheet P of a desired size by a command from an operation unit (not shown), the drive motor 29 rotates forward. In the normal paper feeding state, the paper feed cassettes 3 to 6 in all the stages are pushed into the unit U, and are in the raised position against the interlocking body 56 and the urging spring 57. Therefore, the rack 5
The planetary arms 50 and 51 rotate clockwise in FIG. 5 by the partial gears 52 and 53 meshed with the gears 4 and 55, so that the first planetary gear 34 meshes with the third gear 36 of the corresponding stage and feed rollers. While the power is transmitted to the pair 10a (10b) and the like, the third planetary gear 45 meshes with the first initial transmission gear 47 in the lower gear transmission mechanism, and from the gear transmission mechanism 25 to the lower gear transmission mechanism 26 (27) and the like. Power can be transmitted in series.

By the operation of the actuator 44 for the sheet feeding unit of the designated stage among the above, the sheet feeding roller can be intermittently rotated only one rotation, but the sheet feeding rollers of the other stages are not rotated. The held paper P is picked up by a paper feed roller 9a (9b or the like) at a predetermined stage, and the paper
Can be conveyed upwards.

When a paper jam occurs at an arbitrary stage,
The occurrence of paper jam is detected by a sensor (not shown), and in response to this, the drive motor 49 automatically stops and informs the display panel of liquid crystal or the like of the occurrence of the paper jam. The operator pulls out at least the uppermost sheet cassette 3. FIG. 6 shows a state in which the uppermost sheet cassette 3 is pulled out. As a result, the pressing piece 58 is separated from the contact portion 56a of the interlocking body 56 as shown in FIG.
It is lowered by the force of 7. By this downward movement, the planetary arms 50, 51 rotate counterclockwise in FIG. 6 via the partial gears 52, 53 engaged with the rack portions 54, 55 of the interlocking body 56, and the third gear at the uppermost stage. 36 and adjacent second
As a result of the disengagement of the sheet feeding unit U4 from the first initial transmission gear 47, the feed roller pair and the sheet feeding roller at the uppermost stage and the lower stage are in a free state released from the engagement of the gears. The paper jammed in the step can be easily removed with a light force.

When the paper cassette of a given arbitrary stage is pulled forward, engagement with the third gear 36 of that stage and the first initial transmission gear 47 of the adjacent lower stage is released, and as a result, the same as described above. Then, the feed roller pair and the feed roller of the corresponding stage and the stage below the stage are in a free state released from the engagement of the gears, so that the jammed paper in these stages can be easily removed with a light force. It is.

When the pressing piece 58 is separated from the contact portion 56a, a stopper 59 (see FIGS. 6 and 7) for restricting the lowering position of the interlocking body 56 is provided, so that the rack portions 54 and 55 are provided. The rotation range of the planetary arms 50 and 51 via the meshed partial gears 52 and 53 (the third gear 3
6 and the distance from the first initial transmission gear 47).

The power transmission to the feed roller 10a and the lower gear transmission mechanism is released only by the reverse rotation of the drive motor 29, and only the uppermost gear transmission mechanism 25 is constituted.
Below the paper feed unit U2, each paper feed cassette 4 (5,
In the pull-out movement of 6), the transmission of power to the lower feed roller and the gear transmission mechanism may be released by the above-described example mechanism.

If the uppermost sheet feeding unit U1 is set in the main body case 2 of the image forming apparatus and the lower sheet feeding unit can be arbitrarily added as an option, the size of the sheet used by the user can be increased. And the number of paper qualities can be appropriately added or deleted.

[0037]

As described above, the image forming apparatus according to the first aspect of the present invention has an image forming section for printing on a sheet, and a sheet feeding path for conveying the sheet to the image forming section. And a paper feed cassette for supplying paper toward the paper feed transport path is arranged in a detachable manner in upper and lower stages, and a gear transmission mechanism corresponding to each stage of each of the feed cassettes is arranged in a vertical direction. So that power is transmitted in series from one drive motor to the respective gear transmission mechanisms from the upstream side to the downstream side in a serial manner, so that power is transmitted to at least the sheet feed rollers in the respective sheet cassettes. In the image forming apparatus having the above-described structure, a first planetary gear mechanism for interrupting power transmission to a sheet feeding / conveying roller in a corresponding stage and a gear transmission mechanism on a downstream side are provided in each of the gear transmission mechanisms. A second planetary gear mechanism for interrupting force transmission, and when the one drive motor rotates forward, power is transmitted to all the gear transmission mechanisms and the sheet feeding conveyance rollers, while the one drive motor is driven. The first and second planetary gear mechanisms are operated so that the power transmission to all the gear transmission mechanisms and the sheet feeding / conveying rollers is shut off when the motor rotates in the reverse direction.

According to this configuration, while the plurality of gear transmission mechanisms are connected in series, the switching between the forward rotation and the reverse rotation of one drive motor is only required for the first planetary gear mechanism and the second planetary gear mechanism. The operation can be switched between the engagement and the disengagement, whereby the gear at the position where the paper jam occurs can be easily set in the free state, and the effect that the jammed paper can be removed with a light force can be obtained.

On the other hand, an image forming apparatus according to the present invention includes an image forming section for printing on a sheet, and a sheet feeding path for conveying the sheet to the image forming section. The paper feed cassettes for feeding paper toward the path are arranged so that they can be pulled out in upper and lower multi-stages, and gear transmission mechanisms corresponding to the respective stages of the respective paper feed cassettes are vertically connected, and one drive An image forming apparatus configured to transmit power to at least a sheet feeding roller in each of the sheet cassettes by transmitting power in series from an upstream side to a downstream side with respect to each of the gear transmission mechanisms from a motor. In each of the gear transmission mechanisms, a first planetary gear mechanism for interrupting power transmission to a sheet feeding / conveying roller in a corresponding stage and a power transmission to a downstream gear transmission mechanism are interrupted. When the sheet cassette is moved in the pull-out direction at least between the first and second planetary gear mechanisms in the uppermost or any stage of the sheet cassette, the corresponding stage is provided. When the paper feed cassette is set in the paper feed state, the power transmission to the paper feed transport roller of the corresponding stage and the power transmission to the adjacent downstream gear transmission mechanism are simultaneously cut off. And an interlocking mechanism for operating the first and second planetary gear mechanisms in order to simultaneously achieve the power transmission of the first and second planetary gear mechanisms.

According to this configuration, by merely pulling out at least the uppermost sheet or an arbitrary sheet cassette in which the paper jam has occurred, the power transmission to the sheet conveying roller at that step and the adjacent downstream gear transmission mechanism. As a result, it is possible to remove the jammed paper very easily with a light force.

According to a third aspect of the present invention, there is provided the image forming apparatus according to the first or second aspect, wherein the first and second planetary gears of the respective lower-stage paper feed cassettes and the lowermost stage are arranged. When the paper cassette is moved in the pull-out direction between the mechanism and the mechanism, power transmission to the paper feed roller of the corresponding stage and power transmission to the adjacent downstream gear transmission mechanism are simultaneously shut off, When the paper cassette is set in the paper feeding state, the first and second power transmissions are simultaneously performed to the corresponding paper feed conveyance roller and the adjacent downstream gear transmission mechanism. It has an interlocking mechanism for operating the planetary gear mechanism.

In this configuration, at the lower stage than the uppermost stage, only by pulling out the sheet cassette at the stage where the paper jam has occurred, the sheet feed roller at the position of the corresponding stage can be set to the free state. Paper jam at the step can be easily removed.

According to a fourth aspect of the present invention, in the image forming apparatus according to any one of the first to third aspects, the uppermost sheet feeding cassette is provided in a main body case of the image forming apparatus. While the drive motor is arranged, the lower paper cassette is configured so as to be additionally connected to the lower part of the main body case, so that the number of paper sizes and the quality of paper used by the user can be adjusted. This makes it possible to easily add or delete the units of the paper feed cassette as needed.

[Brief description of the drawings]

FIG. 1 is a schematic sectional side view of a multi-stage paper cassette type printer according to the present invention.

FIG. 2 is a side view of the sheet feeding unit according to the first embodiment.

FIG. 3 is a side view showing a state where the drive motor in the first embodiment is rotated forward.

FIG. 4 is a side view showing a state where the drive motor is rotated in the reverse direction.

FIG. 5 is a side view of a sheet feeding unit according to a second embodiment.

FIG. 6 is a side view showing a state in which the uppermost sheet feeding unit in the second embodiment is pulled out.

FIG. 7 is a cross-sectional view of a main part of a configuration in which the meshing of the planetary gears is interlocked with the pulling-out movement of the paper feeding unit.

[Explanation of symbols]

2 Printer body 3 First paper cassette 4 Second paper cassette U1, U2, U3, U4 Paper feed units 9a, 9b, 9c, 9d Paper feed rollers 10a, 10b, 10c, 10d Feed roller pairs 25 as transport rollers First gear transmission mechanism 26 Second gear transmission mechanism 27 Third gear transmission mechanism 29 Drive motor 34 First planetary gear 36 Third gear 45 Second planetary gear 47 First initial transmission gear

Claims (4)

[Claims] An image forming section for printing on a sheet, and a sheet feeding path for conveying the sheet to the image forming section, and a sheet feeding cassette for feeding the sheet toward the sheet feeding path is vertically moved. It is arranged so that it can be detached in multiple stages, and gear transmission mechanisms corresponding to each stage of each of the paper feed cassettes are connected in the vertical direction, from one drive motor to each gear transmission mechanism from the upstream side In an image forming apparatus configured to transmit power to at least a paper feed roller in each of the paper feed cassettes by transmitting power in series to a downstream side, a corresponding stage is provided in each of the gear transmission mechanisms. And a second planetary gear mechanism for interrupting power transmission to a downstream gear transmission mechanism, and a first planetary gear mechanism for interrupting power transmission to a sheet feeding and transporting roller. When forward rotation of motor, while the power transmission to all of the gear transmission mechanism and the sheet feed conveying roller,
When the one drive motor is rotated in the reverse direction, the first and second planetary gear mechanisms are operated so that the power transmission to all the gear transmission mechanisms and the paper feed rollers is shut off. Characteristic image forming apparatus. 2. An image forming section for printing on a sheet, and a sheet feeding path for conveying the sheet to the image forming section, and a sheet feeding cassette for feeding the sheet toward the sheet feeding path is vertically moved. It is arranged so that it can be pulled out in multiple stages, and gear transmission mechanisms corresponding to each stage of each of the paper feed cassettes are connected in the vertical direction, from one drive motor to each gear transmission mechanism from the upstream side In an image forming apparatus configured to transmit power to at least a paper feed roller in each of the paper feed cassettes by transmitting power in series to a downstream side, a corresponding stage is provided in each of the gear transmission mechanisms. And a second planetary gear mechanism for interrupting power transmission to a downstream gear transmission mechanism. Alternatively, between the first and second planetary gear mechanisms in the sheet cassette of an arbitrary stage, when the sheet cassette is moved in the pull-out direction, the power is transmitted to the sheet conveyance roller of the corresponding stage and the downstream adjacent to the power transmission roller. While the power transmission to the gear transmission mechanism on the side is simultaneously shut off, when the paper cassette is set in the paper feeding state, the power transmission to the paper conveyance roller of the corresponding stage and the transmission to the adjacent downstream gear transmission mechanism are performed. And an interlocking mechanism for operating the first and second planetary gear mechanisms so as to simultaneously achieve the power transmission of the image forming apparatus. 3. When the paper cassette is moved in the pull-out direction between the paper cassette at the lower stage than the uppermost stage and the first and second planetary gear mechanisms at the respective stages, the paper is fed at the corresponding stage. While the power transmission to the transport roller and the power transmission to the adjacent downstream gear transmission mechanism are simultaneously shut off, when the paper cassette is set in the paper feeding state, the power transmission to the paper transport roller at the corresponding stage is performed. 3. An interlocking mechanism for operating the first and second planetary gear mechanisms to simultaneously achieve the power transmission to the adjacent gear transmission mechanism on the downstream side. The image forming apparatus as described in the above. 4. The uppermost sheet cassette and the drive motor are arranged in a main body case of the image forming apparatus, and the lower sheet cassette is additionally connected to a lower portion of the main body case. The image forming apparatus according to claim 1, wherein the image forming apparatus is configured as described above.