JPH10316258A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent co-rotation of a paper feeding roller or resist roller to prevent jam or tip resist deflection in inputting for inverse rotation driving to a spring clutch while preventing complicatedness of constitution or increase of cost. SOLUTION: For rotation in normal and inverse directions inputted from a stepping motor, only rotation in the normal direction is outputted by a spring clutch 22. A paper feeding roller 7 is rotated based on rotation in the normal direction outputted from the spring clutch 22. A stopper part 31a is provided in a cam 31 to rotate a middle plate 30 which gets closer to/apart from the paper feeding roller 7 for preventing the paper feeding roller 7 from being rotated by the spring clutch 22 when rotation in the inverse direction is inputted from the stepping motor.

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 utilizing an electrostatic process, such as an electrostatic copying machine or a printer, and more particularly to an image forming apparatus of a movable type.

[0002]

2. Description of the Related Art In a conventional image forming apparatus, for example, as shown in FIG. 6, a document table 5 is scanned and placed on a drum type electrophotographic photosensitive member (hereinafter referred to as "photosensitive drum") 1 as an image carrier. 2. Description of the Related Art There is an original table movable type copier that forms an electrostatic latent image, visualizes the electrostatic latent image, and transfers the image to a sheet.

That is, in the above-described copying machine, the photosensitive drum 1 is moved around a charging means 2 for uniformly charging the photosensitive drum 1 and a document table 5 to scan the photosensitive drum 1 around the photosensitive drum 1.
Developing means 3 for developing the electrostatic latent image formed on the photosensitive drum 1 and transferring means 4 for transferring the toner image on the photosensitive drum 1 to the sheet S
Further, a cleaning unit 17 for removing the toner remaining on the photosensitive drum 1 is provided.

Further, the sheet S is placed on a paper feed cassette 13, rotates a paper feed roller 7 as a rotating body based on an image command, is conveyed to a registration roller 6 as a rotating body, and is exposed to light. The toner is conveyed to the transfer nip in synchronization with the toner image on the drum 1.

[0005] The toner image transferred onto the sheet S by the transfer means 4 is conveyed to a fixing means 8 where it is fixed and discharged.

In the above copying machine, the sheet S fed by the feed roller 7 is temporarily stopped by the registration roller 6 in order to synchronize with the scanning of the original table (optical system), and then restarted to form an image. Is done.

As shown in FIG. 8, the document table 5 transmits the forward / reverse rotation of a stepping motor 26 as a drive source to a rack 27 via a gear train 18 so that an arrow Y shown in FIG. 7A and the back direction of the arrow X shown in FIG.

The operation of the conventional copying machine having the above-described configuration will be described with reference to FIGS.

When a copy operation start signal is input, the stepping motor 26 rotates in the forward direction, and the document table 5 moves in the back direction indicated by the arrow X in FIG. 7A. At this time, the solenoid 23 that controls the spring clutch 22 disposed coaxially with the paper feed roller 7 operates, the engagement between the solenoid lever 23a and the claw 22a of the spring clutch 22 is released, and the paper feed roller 7 rotates. Start.

[0010] An intermediate plate 30 which is one of the feed separating means is provided.
Is a cam 15 fixed integrally on the shaft of the paper feed roller 7,
The sheet 14 is moved in the direction in which the sheet feeding roller 7 comes into contact with the projecting piece 14 projecting from the middle plate 30 so as to engage with the cam 15, and as a result, the sheet S feeding operation is started.

When the sheet S is fed to the registration roller 6 and the document table 5 moves to a predetermined position for scanning the document, the stepping motor 26 starts to rotate in the reverse direction, and the document table 5 As shown in FIG. 7B, the movement of the illustrated arrow Y in the scanning direction is started.

When the document table 5 moves to a predetermined position, the control ring for controlling the rotation of the spring clutch 25 disposed coaxially with the registration roller 6 is disengaged from the lever 28 operated by the solenoid 24. , Registration roller 6
Rotates to start image formation on the sheet S.

When the paper feeding operation is controlled each time the paper feeding roller 7 makes one rotation, the claw portion 22a of the spring clutch 22 and the solenoid lever 23a are engaged again when the paper feeding roller 7 makes one rotation. Then, the rotation of the sheet feeding roller 7 is stopped, and the sheet feeding operation is stopped. At this time, the middle plate 30 is retracted to a predetermined position separated from the paper feed roller 7 by the cam 15. In addition, the rotation preventing operation of the feed roller 7 and the middle plate 3
The evacuation operation of 0 ends when the stepping motor 26 rotates forward.

Next, the spring clutch 22 of the above-described device will be described with reference to FIG.

The input gear 19 and the drive transmission gear 16 are rotatably mounted on a common shaft 21, and a plate extends over a clutch cylinder 20 a integral with the input gear 19 and a clutch cylinder 20 b integral with the drive transmission gear 16. A spring 20c in which a spring is wound in a coil shape is inserted.

The spring 20c is formed such that its inner diameter in a normal state is smaller than the outer diameters of the clutch bodies 20a and 20b, as shown in FIG. 9 (c). Further, one end 20c ₁ of the spring 20c is locked on the drive transmission gear 16 side, and the other end 20c ₂ is inserted into the outer periphery of the clutch body 20a and is rotatable with respect to the shaft 21.
d.

Thus, when the input gear 19 rotates in the direction of arrow a in FIG. 9A (the direction in which the photosensitive drum 1 is rotated during image formation), the locking claw of the control ring 20d engages with the solenoid lever 23a. When the rotation is restricted (fixed state), the inner diameter of the spring 20c expands, and the clutch cylinder 20
When the input gear 19 rotates, the rotational force is not transmitted to the drive transmission gear 16.

If the rotation of the control ring 20d is not restricted (free state), the inner diameter of the spring 20c is
0a, 20b, and the spring 20c remains closed with respect to the clutch cylinders 20a, 20b, so that the torque of the input gear 19 is transmitted to the drive transmission gear 16. Become.

When the rotation of the input gear 19 is stopped, and when the spring 20c is in the closed state, the drive transmission gear 16 can idle in one direction but is restricted in the other direction. You. On the other hand, when the spring 20c is in the open state, the drive transmission gear 16 can idle in one direction,
The other side can be slightly idle. Note that a number of locking claws are provided on the outer peripheral surface of the control ring 20d of the spring clutch 25 that controls the rotation of the registration roller 6.

The control ring 20d of the spring clutch 25 is not limited to a large number of locking claws, but may be one. Further, the case where the output side is directly the paper feed roller 7 or the registration roller 6 instead of the drive transmission gear 16 is also included.

An image is formed by the rotational force transmitting mechanism of the copying machine having the above configuration.

By the way, in the above-mentioned conventional example, when the stepping motor 26 rotates forward and backward, the driving force of the reverse rotation of the stepping motor 26 is also inputted to the spring clutches 22 and 25.

[0023]

However, due to the construction, the spring clutches 22 and 25 are capable of idling with respect to the reverse rotation of the stepping motor 26, so that the spring clutches 22 and 25 are idling. Thus, the above-described operation of the document table 5 can be achieved without the reverse rotation of the paper feed roller 7 and the registration roller 6, but the idling torque at the time of the reverse rotation of the spring clutches 22 and 25 is reduced by the paper feed roller 7
And when it becomes heavier than the rotational load of the registration roller 6,
With the reverse rotation of the spring clutch 22, the paper feed roller 7
However, the registration roller 6 rotates in the reverse direction together with the reverse rotation of the spring clutch 25.

In addition, since the idling torque and the rotational load differ depending on the conditions of the apparatus main body such as the variation and durability of the components of the spring clutches 22 and 25, it is difficult to define conditions for preventing reverse rotation. It is. Therefore, there were the following problems.

When the paper feed roller 7 rotates in the reverse direction, the sheet S is pushed out in the reverse direction, and the sheet S cannot be separated and fed at the next paper feed.

When the registration roller 6 rotates in the reverse direction, the fed sheet S cannot reach the nip of the registration roller 6 and cannot be conveyed when the registration roller 6 rotates forward, or the jam or the leading end adjustment position is It fluctuates.

In order to obtain a reliable rotational load, it is necessary to provide a brake means and the like, which causes a complicated configuration and an increase in cost.

The present invention has been made to solve the above-described problems, and eliminates the complexity of the configuration and the increase in cost. It is an object of the present invention to provide an image forming apparatus which does not cause a jam and a registration error at a leading end.

[0029]

In order to achieve the above object, an image forming apparatus according to the first aspect of the present invention rotates in both forward and reverse directions to reciprocally slide a document table on which a document is placed. A drive source, a drive transmission unit having a clutch mechanism that inputs rotation in both forward and reverse directions from the drive source, and outputs only rotation in one of the forward and reverse directions, and one output from the drive transmission unit. A rotating body that rotates based on rotation in one direction, the image reading is performed by passing the platen once moved to one side to the opposite side while passing above the image reading unit. Wherein when a driving force for rotation in either the forward or reverse direction is input from the drive source to the drive transmission means between the drive transmission means and the rotating body, the clutch Prevents rotation of the rotating body by a mechanism Characterized in that a stopper means.

According to the second aspect of the present invention, the stopper means includes a claw projecting from a support plate that rotates about a rotation axis so as to come into contact with and separate from the rotating body, and the rotating body. And a cam attached to a shaft of
When the rotating body rotates together, the rotating body has an engagement surface that engages with the claw to stop the rotation.

According to the third aspect of the present invention, the stopper means includes a control ring provided on the drive transmission means, and a control lever engaged with the control ring. When the rotating body rotates together with the control lever, the rotating body has an engaging surface that stops rotating together with the control lever.

According to the fourth aspect of the present invention, the rotating body is a paper feed roller.

According to the invention described in claim 5, the rotating body is a registration roller.

According to the invention described in claim 6, the drive transmitting means is a spring clutch.

[Operation] Based on the above configuration, both forward and reverse rotations are input to the drive transmitting means from the drive source which rotates in both forward and reverse directions to reciprocally slide the document table. The drive transmission means outputs only rotation in either one of the forward and reverse directions via the clutch mechanism. Then, the rotating body rotates based on rotation in one direction output from the drive transmission means. Also, even if a driving force for rotation in either the forward or reverse direction is input from the drive source to the drive transmission means, and rotation is transmitted from the drive transmission means to the rotating body, the drive transmission means and the rotating body The co-rotational rotation is stopped by a stopper means provided between the two.

[0036]

Embodiments of the present invention will be described below in detail with reference to the drawings. <First Embodiment> FIG. 1 is a perspective view showing a rotational force transmitting device according to a first embodiment of the present invention, and FIG. 2 is a perspective view showing a main part of FIG. FIG. In addition,
1 and 2, the same or equivalent components as those shown in FIGS. 6 to 9 are denoted by the same reference numerals, and redundant description will be omitted.

In this embodiment, the stepping motor 2
6, the invention will be described by showing a driving force transmission device in which the rotational force of both forward and reverse rotations is transmitted to a spring clutch 22 as a driving transmission means.

In FIG. 1, a spring clutch 22 is provided on the shaft of the paper feed roller (rotary body) 7 and an intermediate plate (one of the separation feeding means for the paper feed roller 7). A cam 31 for moving (vertically moving) the support plate (30) so as to press and separate it is provided.

The middle plate 30 is rotated by an elastic member 40 so as to be urged upward (toward the paper feed roller 7).
Is rotatably supported about a center, and a turning piece 32 having a claw 32a abutting on the cam 31 is provided upright at an end thereof.

The cam 31 has a spring clutch 2 on its cam surface.
A stopper portion 31a is formed to engage with the pawl 32a of the rotating piece 32 during the reverse rotation of the roller 2 to prevent the feed roller 7 from rotating together.

The spring clutch 22 has a claw 22a that engages with the lever 23a of the solenoid 23.
When the lever 23a is engaged with the claw portion 22a by the non-excitation of the lever 3, the drive force transmitted from the input gear 19 of the spring clutch 22 to the drive transmission gear 16 is cut off, and the solenoid 23
When the lever 23a is separated from the claw portion 22a by the excitation of the sheet feeding roller 7, the rotation driving force in the direction of the arrow R22 shown in FIG.
Is transmitted to

FIG. 1 shows that the claw portion 22a of the spring clutch 22 and the lever 23a of the solenoid 23 are engaged, the rotation of the stepping motor 26 is not transmitted to the paper feed roller 7, and the rotational driving force is cut off by the spring clutch 22. The state shown is shown.

Also, the intermediate plate 30 shown in FIG.
The sheet S can be set between the sheet S and the middle plate 30, that is, the sheet S is in a standby state for separating and feeding.

The cam 31 shown in FIG. 1 is provided with a rotating piece 32 at a stopper portion 31a for preventing the paper feed roller 7 from rotating.
3 shows a state in which the claw 32a is engaged. The stopper 31a of the cam 31 and the claw 32a of the rotating piece 32
The stopper means is constituted by this.

Next, the detailed shape of the stopper portion 31a and the function of the stopper portion 31a when a reverse rotation driving force is applied to the spring clutch 22 will be described with reference to FIGS. 2 (a) and 2 (b). .

In this embodiment, the stopper 31a
Includes an inclined surface 31a ₁ relief operable without claws 32a engage when the cam 31 rotates in the R22 direction, the cam 31
There is formed in a V-shaped groove so as to have a engaging surface 31a ₂ of claws 32a engage when rotated in the counter R22 direction. In addition, the cam 31 has a claw 32a of the rotating piece 32,
Even if it rotates in the direction and contacts the step 31b of the cam 31,
The angle is formed so as to be able to get over the step 31b.

[0047] Further, the engagement surfaces 31a ₂ and the claw 32a and the engagement portion line drawn at right angles to a line drawn along the surface of both the (point) (C) (D) is pivotable piece 32 The cam 31 has a predetermined angle θ (θ> 0) with respect to a line connecting the rotation shaft 30a, which is the center of rotation of the (middle plate 30), and the engaging portion (point) of the two.
Is rotated in the direction indicated by the arrow R22, the rotating piece 32 and the cam 31 have a biting relationship, and as a result, the rotating piece 32 prevents reverse rotation of the (feed roller 7) (stopper). To act as).

That is, the reverse rotation driving force is applied from the stepping motor 26 via the gear train 18 to the spring clutch 22.
When a force is applied to rotate the cam 31 in the direction opposite to the arrow R22 in the figure, a force for urging the middle plate 30 to rotate downward away from the paper feed roller 7 does not act, and the rotating piece 32
Exerts a force for encouraging rotation in the direction of the arrow R32 shown. That is, since the rotating piece 32 bites into the stopper portion 31a to be in a self-contained state, as a result, the paper feed roller 7 is not rotated together.

In this embodiment, when the rotating piece 32 is engaged with the stopper 31a of the cam 31, the sheet S
Of course is set to the separation feeding standby state.

In this embodiment, the spring clutch 22 is described as being provided coaxially with the paper feed roller 7, but the paper feed roller 7 and the clutch spring 22 are not provided coaxially. Of course, it is good. <Second Embodiment> Next, a second embodiment will be described with reference to FIGS.

FIG. 3 is a perspective view showing a driving force transmitting device according to a second embodiment of the present invention, FIG. 4 is an exploded perspective view of the spring clutch 35 shown in FIG. 3, and FIG. It is a front view extracted and shown. 3 to 5, FIG.
Components that are the same as or equivalent to those shown in FIG. 2 are denoted by the same reference numerals, and redundant description is omitted.

In this embodiment, a spring clutch 3 as a drive transmitting means is coaxial with a registration roller (rotating body) 6.
The spring clutch 35 has an input gear 35f, a drive transmission gear 35d disposed coaxially with the input gear 35f, and a shaft of the input gear 35f and the drive transmission gear 35d. And a control ring 35c that locks one end of the spring 35e.

The control ring 35c of the spring clutch 35
The self is provided with a plurality of stopper portions 35a provided for prevention of entrainment. This stopper portion 35a has
And engagement surface 35a ₁ and the claw portion 34a does not engage escape operable inclined surfaces 35a ₂ to prevent rotation around the take pawl portion 34a engages with the control lever 34 is formed.

[0054] The control ring 35c of the spring clutch 35 and the engagement surface 35a ₁ of the claw portion 34a and the stopper portion 35a of the control lever 34 is rotated in the arrow R35 direction as shown in FIGS. 3 and 5 engage By doing so, the spring clutch 35
The transmission of the rotational driving force by which the and the registration rollers 6 rotate together is cut off. Incidentally, the stopper means is constituted by a claw portion 34a and the engagement surface 35a _1.

The spring clutch 35 and the control lever 34
Engaging surface 35a ₁ and the inclined surface 3 encourage stopper function with
Angle of 5a ₂ is at a position angle as shown in FIG. 5, the same effect as the first embodiment.

As a result, even if a reverse driving force is input to the spring clutch 35, the registration roller 6 does not rotate.

The sheet S is rotated in synchronization with the start position of the toner image on the photosensitive drum 1 by rotating the registration roller 6.
When the control lever 35 is conveyed, a solenoid (not shown) is operated to separate the control lever 34 from the control ring 35c.

As described above, when a reverse driving force is applied to the spring clutch 35 for operating the registration roller 6, the control lever 34 is moved to the engagement surface 35 of the stopper 35a.
from being rotated together registration roller 6 is engaged with a ₁ can be prevented.

Further, in the above-described embodiment, a spring clutch that transmits the forward / reverse rotation of the stepping motor 26 only in one direction and does not transmit the other rotation is provided on the shaft of the registration roller 6 or the sheet feeding roller 7. However, the present invention is not limited to the registration roller 6 and the paper feed roller, and may be provided on a rotating body such as a conveyance roller on the upstream side of the registration roller in the sheet conveyance direction. A stable loop can be formed.

Further, although the spring clutch is coaxial with the registration roller and the paper feed roller, it goes without saying that the spring clutch need not be coaxially arranged.

[0061]

As described above, according to the present invention, a driving force for rotation in either the forward or reverse direction is input from the drive source to the drive transmission means, and the drive transmission means applies a rotation force to the rotating body. Even if the rotation which is not originally transmitted is transmitted, the co-rotating rotation is stopped by the stopper means provided between the drive transmission means and the rotating body, so the brake means for stopping the reverse rotation of the rotating body is provided. This eliminates the necessity to provide, prevents the rotation of the rotating body when the reverse rotation drive is input to the drive transmission means, without complicating the configuration and increasing the cost, so that the sheet jam and the registration error at the leading end do not occur. The effect is obtained.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a driving force transmission device according to a first embodiment of the present invention.

FIGS. 2A and 2B are extracted main parts of FIG. 1, wherein FIG. 2A is a perspective view and FIG. 2B is a front view.

FIG. 3 is a perspective view showing a driving force transmission device according to a second embodiment of the present invention.

FIG. 4 is an exploded perspective view showing the spring clutch of FIG. 3;

FIG. 5 is a front view showing main parts extracted and shown.

FIG. 6 is a schematic configuration diagram showing an example of a conventional image forming apparatus of a movable platen type.

FIGS. 7A and 7B show an image forming apparatus of a platen movable type, wherein FIG. 7A is an explanatory view showing a state in which the platen is scanned in an arrow X direction shown in FIG. FIG. 9 is an explanatory diagram showing a state in the case.

FIG. 8 is a perspective view showing an example of a conventional driving force transmission device.

FIG. 9 shows a conventional spring clutch, wherein (a) is a perspective view,
(B) is a sectional view of the same, and (c) is a perspective view showing a spring portion.

[Explanation of symbols]

Reference Signs List 6 rotating body (registration roller) 7 rotating body (paper feed roller) 22 drive transmission means (spring clutch) 26 drive source (stepping motor) 30 support plate (middle plate) 31 cam 31a stopper portion 31a ₁ inclined surface 31a ₂ engagement Surface 32a Claw 34 Control lever 35 Drive transmission means (spring clutch) 35a Stopper means 35a ₁ engagement surface 35a ₂ inclined surface 35c control ring

Claims (6)

[Claims] 1. A drive source rotating in both forward and reverse directions for reciprocatingly sliding a document table on which a document is placed, and inputting rotations in both forward and reverse directions from the drive source, and in either one of forward and reverse directions. Drive transmission means having a clutch mechanism that outputs only rotation,
A rotating body that rotates based on rotation in any one direction output from the drive transmission means, and reads an image while moving the platen once moved to one side to the opposite side. An image forming apparatus configured to be passed above an image reading unit, wherein: between the drive transmission unit and the rotating body, rotation of the drive source to the drive transmission unit in one of the forward and reverse directions. An image forming apparatus, comprising: stopper means for preventing the rotation of the rotating body by the clutch mechanism when a force is input. 2. The stopper means comprises: a claw projecting from a support plate that rotates about a rotation shaft so as to come into contact with and separate from the rotating body; and a cam attached to a shaft of the rotating body. The image forming apparatus according to claim 1, wherein the cam has an engagement surface that engages with the claw to stop the rotation when the rotating body rotates. . 3. The control device according to claim 1, wherein the stopper includes a control ring provided on the drive transmission unit, and a control lever that engages with the control ring. The image forming apparatus according to claim 1, further comprising an engagement surface that engages with the control lever to stop the co-rotation. 4. The apparatus according to claim 1, wherein the rotating body is a paper feed roller.
The image forming apparatus as described in the above. 5. The apparatus according to claim 1, wherein the rotating body is a registration roller.
The image forming apparatus as described in the above. 6. The drive transmission device according to claim 1, wherein the drive transmission unit is a spring clutch.
The image forming apparatus as described in the above.