JPH10198136A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device capable of synchronizing an image formed by an image forming part with a sheet without forming a loop. SOLUTION: In the case of reading the image, a carrying means carries the sheet to a transfer part for transferring the image formed by the image forming part to the sheet, and also a detection means detects that the sheet carried by the carrying means reaches a specified position. In the case of reading the image, a control means controls a release means 33 to release the original platen stopping operation of a stopping means 31 for temporarily stopping an original platen 1A restored to a home position according to a signal from the detection means so that the sheet carried to the transfer part may be synchronized with the transferred image. Thus, the image formed by the image forming part is synchronized with paper without forming the loop.

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 provided with a horizontally movable platen, and more particularly, to a timing for conveying a sheet to a transfer section for transferring an image formed by the image forming section to the sheet. It is.

[0002]

2. Description of the Related Art Conventionally, a copying machine, which is an example of an image forming apparatus, includes a document table on which a document is placed, and a main body on which the document table is horizontally movably mounted. FIG.
Numeral 0 is a diagram showing the configuration of such a copying machine. In such a copying machine, an image of a document is copied onto a sheet under the control described below.

That is, when a copy start signal is input by a copy button, a main motor (not shown) starts operating, and thereby a document table 1A including a platen glass 1 on which a document is placed.
Moves the upper surface of the main body 1B to the left as shown by the arrow A, and goes to the home position to start scanning from the image tip.

On the other hand, at the same time, a photosensitive drum 4 as an image carrier provided in the main body, a developing sleeve 5 for developing an electrostatic latent image on the photosensitive drum 4, and a developed image on the photosensitive drum 4 are transferred. Roller 6, a fixing film for fixing an image on paper, a fixing device 10 including a pressure roller, and the like are simultaneously started to rotate by a main motor. In addition,
At this time, the paper feed roller 7 and the pair of registration rollers 8a and 8b, which are paper feeding means for feeding and transporting the paper, are turned off by the operation of a clutch provided in a drive system for transmitting the rotation of the main motor. Has stopped.

By the way, when the document table 1A reaches the home position, the document table 1A is turned over and the scanning operation of the image is started. That is, the document table 1A moves rightward as shown by the arrow B so as to pass through the irradiation point of the exposure light of the lamp 2 for irradiating the document. The exposure light passes through the SELFOC lens 3 and forms an image on the photosensitive drum 4.

The paper feed roller 7 starts rotating before the document table 1A starts the scanning operation, and starts feeding copy paper (hereinafter referred to as paper). At this time, the pair of registration rollers 8a and 8b is still in a state where the rotation is interrupted by the clutch. Therefore, the fed sheet has its leading end inserted into the nip portion of the pair of registration rollers 8a and 8b. Be stopped. The paper feed roller 7, which has once started rotating, stops its rotation by clutch control after performing one rotation operation, and ends the paper feeding operation. As a result, the leading end of the sheet is stopped by the pair of registration rollers 8a and 8b, and the sheet is temporarily waited in a form where a loop is formed between the sheets by the amount of being pushed by the sheet feed roller 7 on the downstream side.

Next, the clutch is engaged so that the sheet reaches the transfer portion at the same timing that the image corresponding to the image tip of the document reaches the transfer portion, thereby the registration roller pair 8
The rotation of a and 8b starts, and the sheet starts to be conveyed to the transfer section. Thereafter, the sheet is transferred in synchronization with the image on the photosensitive drum 4, and thereafter, the sheet is transferred to the transport unit 9, the fixing device 10.
After passing through all the processes of copying, the paper is discharged out of the machine.

[0008]

However, in such a conventional image forming apparatus, in order to synchronize the image on the photosensitive drum 4 with the sheet, the registration rollers 8a and 8b are intermittently stopped to copy. Since the paper is formed so as to form a loop, there are the following drawbacks. (1) For example, in the case of thick paper such as 128 g / mm ² paper or a postcard business card, it is difficult to form a loop. is there. (2) In the state of (1), there is a possibility that rubber traces caused by the paper feed roller adhere to copy paper. (3) Since a clutch for disconnecting and connecting the drive to the feed roller and the registration roller is required, an increase in cost cannot be avoided.

Therefore, the present invention has been made to solve such a conventional problem, and is intended to synchronize an image formed in an image forming unit with a sheet without forming a loop. It is an object of the present invention to provide an image forming apparatus capable of performing the following.

[0010]

According to the present invention, there is provided a document table on which a document is placed, and a main body having an image reading section and an image forming section and having the document table mounted on a top surface thereof so as to be horizontally movable. The image forming apparatus performs reading by returning the original platen once moved to the side to the original position on the upper surface of the main body while passing above the image reading unit. A transfer unit that transfers the obtained image to a sheet, a sheet feeding unit that takes out the sheet from the sheet placement unit when reading an image, and a conveyance unit that conveys the sheet taken out of the sheet feeding unit to the transfer unit. Detecting means for detecting that the sheet conveyed by the conveying means has reached a predetermined position; and stopping means for temporarily stopping the document table returning to the original position on the upper surface of the main body when reading the image. Release means for releasing the stop operation of the stop means; and, in synchronization with the sheet conveyed to the transfer section and the transferred image, upon reading the image, the release means responds to a signal from the detection means. And control means for controlling the release means so as to release the document table stop operation of the stop means.

Further, the present invention is characterized in that the conveying means is provided at a position close to the paper feeding means.

Further, the present invention is characterized in that a driving means for moving the platen is provided, and the paper feeding means and the conveying means are selectively driven by the driving means.

Further, as in the present invention, when reading an image,
The sheet is conveyed by a conveying unit to a transfer unit that transfers an image formed by the image forming unit to the sheet, and the detecting unit detects that the sheet conveyed by the conveying unit has reached a predetermined position. I do. And the control means,
At the time of image reading, the original platen stop operation of the original unit that temporarily stops the original platen returning to the original position is released by the release unit in response to a signal from the detection unit, and is transferred to the sheet conveyed to the transfer unit. Synchronize with the image. Thus, it is possible to synchronize the image formed by the image forming unit and the sheet without forming a loop.

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic sectional view of a copying machine as an example of an image forming apparatus according to a first embodiment of the present invention.
In the same figure, the same reference numerals as those in FIG. 9 indicate the same or corresponding parts.

In FIG. 1, 8A and 8B as transport means
Denotes a pair of conveying rollers, and the pair of conveying rollers 8A and 8B and the sheet feeding roller 7 are arranged as close as possible to a transfer section provided with the photosensitive drum 4 and the like. A sensor 11 (photo interrupter, micro switch, or the like) detects that the actuator 11a falls down on the sheet conveyed to the transfer unit by the pair of conveying rollers 8A and 8B, thereby detecting the passage of the sheet. It is a registration sensor. The detection signal of the registration sensor 11 is input to a control device 50 for controlling the copying operation of the copying machine.

Reference numeral 12 denotes a separation pad, and 13 denotes one paper feed.
An intermediate plate 14 for assisting the operation of performing only the sheet is a sheet feeding tray.

The document table 1A, the paper feed roller 7, and the pair of transport rollers 8A and 8B are driven by a drive unit shown in FIG. In FIG.
Reference numeral denotes a stepping motor, which is a driving means capable of normal and reverse rotation, and starts clockwise rotation (hereinafter referred to as normal rotation) when a copy start signal is input by a copy button (not shown). Reference numeral 22 denotes a terminal gear rotated by the stepping motor 21 via the first gear 21a.
The rotation of the terminal gear 22 causes the sheet feeding / conveying system gear 2
4. The original table drive gear 30 and the fixing paper discharge gear 34 rotate.

The terminal gear 22 is a step gear, and the small gear 22a of the gear 22 is
And a gear (not shown) integrated with the photosensitive drum 4 via a one-way clutch. The one-way clutch idles when the stepping motor 21 rotates forward, and transmits the drive when the stepping motor 21 rotates counterclockwise (hereinafter referred to as reverse rotation). Therefore, as shown in FIG. 2, when the terminal gear 22 rotates forward, the photosensitive drum 4 does not rotate.

Reference numeral 23 denotes a spring clutch gear which engages with and disengages from the platen driving gear 30 and selectively transmits the rotation of the terminal gear 22 to the platen driving gear 30.
The swinging center gear 26 meshing with the swinging center gear 4
The swing gear 27 meshes with the swing gear 26 and is rotatably held by the swing arm 25. The second gear 27 meshes with the swing gear 26 and rotates forward when the swing arm 25 rotates upward. is there.

Reference numeral 29 denotes a paper feed gear for rotating the paper feed roller 7 which is directly engaged with the second gear 27. The sheet feeding gear 29 has a missing tooth portion. When the missing tooth portion faces the second gear 27, the sheet feeding gear 29 does not mesh with the second gear 27. Therefore, the paper feed roller 7 stops. Reference numeral 28 denotes a fourth gear which meshes with the sheet feeding gear 29 and rotates via a third gear 28a which meshes with the swing gear 26 by the swinging arm 25 rotating counterclockwise.

Then, as described later, the fourth gear 28
Is rotated, the sheet feeding gear 29 rotates in the reverse direction, so that the toothless portion moves from the position facing the second gear 27 to the swing gear 2.
Then, the rotation is made approximately a half turn until the rotation of the motor 6 is stopped, and the rotation is stopped.
When the paper feed gear 29 rotates in the reverse direction, the paper feed roller 7 rotates forward and feeds the paper.
The sheet feeding gear 29 is engaged with the second gear 27.

A transport gear 36 meshes with the paper feed transport system gear 24, and is coaxially disposed with one of the transport rollers 8A and 8B via a one-way clutch (not shown). In addition, this one-way clutch
As shown in the drawing, when the transport gear 36 rotates in the reverse direction, it idles, and when it rotates forward, it engages with one of the transport rollers 8B to rotate the transport roller pair 8A, 8B.

Reference numeral 35 denotes a pressure roller gear directly connected to the pressure roller 10a of the fixing device 10, and a fifth gear meshing with the small gear 34a of the fixing paper discharge system gear 34 serving as a step gear.
It is designed to mesh with the gear 35a and rotate. The fixing and discharging system gear 34 has a configuration in which a one-way clutch is included. The fixing and discharging system gear 34 idles when the fixing and discharging system gear 34 rotates in the reverse direction, and transmits drive when the fixing and discharging system gear 34 rotates in the forward direction. I have.

Reference numeral 31 denotes a platen lever. The platen lever 31 is provided with a registration cam 3 integrated with the platen glass 1 when the platen 1A is reversed and moved from the stop position.
8 and rotates counterclockwise about the rotation shaft 31a. And, like this, the platen lever 3
When 1 rotates, the locking portion 31c formed on the opposite side of the contact portion 31b of the platen lever 31 is received by the solenoid lever 32 and stopped. The platen lever 31 and the solenoid lever 32 are both clockwise biased by a spring (not shown).

Here, due to the pivoting operation of the platen lever 31, the leading end thereof engages with the control ring of the spring clutch 23, whereby the platen driving gear 30 of the spring clutch 23 is moved.
The rotation transmission of the terminal gear 22 to the terminal gear 22 is cut off. Therefore, the platen drive gear 30 stops rotating, and the platen 1A stops. In addition, when reading an image with the platen lever 31, the registration cam 38, the spring clutch 23, and the like, a stop means for temporarily stopping the original table 1A that returns to the original position on the upper surface of the main body is configured.

When the stepping motor 21 is reversed, the original table 1A, which has been moving in the direction A (left) as shown in FIG. 1, temporarily stops at the home position P. The stop position is as follows. Is set to

That is, as shown in FIG. 3, the distance from the stop position P to the exposure position a is L1, and the exposure point b on the photosensitive drum 4 is
L2 (= b to c) and the distance from the point d where the paper feed roller 7 feeds the paper to the separation pad 12 to the transfer unit c is L3, and L1 + L2 <L3. It is set to be.

On the other hand, the paper feed roller 7 rotates by about a half turn at the time of paper feed, so that only the uppermost sheet of the paper stacked on the paper feed tray 14 is fed, and is immediately after. The sheet is further conveyed to the photosensitive drum 4 by the conveying roller pairs 8A and 8B.

Next, the operation from the start of the copying operation of the copying machine having such a configuration until the output is discharged will be described in detail. The optical illumination system, the periphery of the photosensitive drum, and the fixing device are the same as in the conventional example.

When a copy start signal is input by the copy button, the stepping motor 21 starts forward rotation as shown in FIG. The process branches to a gear 30 and a fixing / discharge system gear 34.

That is, due to the forward rotation of the terminal gear 22, the platen driving gear 30 rotates forward through the spring clutch gear 23, and moves the platen 1A in the direction of arrow C as shown in FIG.
(A direction in FIG. 1).

The feed / transport system gear 24 rotates in the reverse direction,
In conjunction with this, the swing gear 26 rotates upward together with the swing arm 25, meshes with the second gear 27, and rotates the second gear 27 forward. At this time, the sheet feeding gear 29 arranged at a position to be meshed with the second gear 27 is stopped without meshing because the toothless portion faces the gear 27 side. As a result, while the original table 1A is moving,
Has stopped. Further, the transport gear 36 is engaged with the paper feed transport system gear 24 and is rotating in the reverse direction, so that the transport roller pair 8A, 8B is stopped similarly to the paper feed roller 7.

Further, the small gear 22a of the terminal gear 22 connected to the gear integrated with the photosensitive drum 4 via a one-way clutch idles when the terminal gear 22 is rotating forward, so that the photosensitive drum 4 stops. ing. The fixing / discharge system gear 34 also idles when rotating counterclockwise, so that the fixing unit and the discharge unit do not operate.

Next, as shown in FIG. 4, when the document table 1A moves to the home position P, the control device 50 determines that the stepping motor 21 has operated for a predetermined number of steps from the start of operation, and temporarily stops the stepping motor 21. It stops and then reverses counterclockwise as shown in the figure.

Here, when the stepping motor 21 is reversed in this way, as shown in FIG.
The document table driving gear 30 rotates in the reverse direction, and the document table 1A moves in the direction of arrow D (the direction B in FIG. 1). Also, this terminal gear 22
With the reverse rotation of, the fixing paper discharge gear 34 rotates forward and the pressure roller gear 35 rotates forward.
The photosensitive drum 4 and the pressure roller 10a start rotating forward and backward, respectively.

Further, at this time, since the feed / transport system gear 24 rotates forward, the swing arm 25 rotates downward by the rotation of the swing center gear 26a.
Is engaged with the fourth gear 28 via the third gear 28a. Here, as described above, the swing gear 26 and the fourth gear 2
When the gears 8 mesh with each other, the sheet feeding gear 29 rotates in the reverse direction, and rotates by approximately half a rotation from the position where the tooth missing portion is opposed to the gear 27 to the position where the missing gear is opposed to the swing gear 26, and stops.

Then, by the rotation of the sheet feeding gear 29,
The paper feed roller 7 rotates forward. At this time, since the transport gear 36 is rotating forward, the transport roller pair 8A,
One of the rollers 8B of FIG. 8B is rotating in the reverse direction in FIG. 1, and the sheet is conveyed by the sheet feeding roller 7 and the conveying roller pair 8A, 8B.

Here, the above stepping motor 21
When the operation after the reversal is reversed is described again, first, as shown in FIG. 1, the document table 1A that has moved in the direction of arrow A (left)
Stop at the home position P once. Also, the paper feed roller 7 rotates forward by about a half turn, and by this rotation, only the uppermost sheet loaded on the paper feed tray 14 is fed, and the paper feed roller pair 8A, 8B immediately after is fed. Further, it is transported to the photosensitive drum 4. Further, the middle plate 13
Performs an operation of retracting from the paper feed roller 7 as shown in FIG. 6 in conjunction with the rotation of the paper feed roller 7 in order to assist the above-described operation of feeding only one paper.

On the other hand, as shown in FIG. 5, when the document table 1A is reversed from the stop position and moves leftward, the registration cam 38 integrated with the platen glass 1 contacts the contact portion 31b of the platen lever 31, This allows the platen lever 31
Rotates counterclockwise about the rotation shaft 31a. When the platen lever 31 rotates in this manner, the locking portion 31c formed on the opposite side of the contact portion 31b of the platen lever 31 is received by the solenoid lever 32 and stopped.

Here, due to the turning operation of the platen lever 31, its tip engages with the control ring of the spring clutch 23, and the rotation transmission of the terminal gear 22 is cut off. Therefore, the platen drive gear 30 stops rotating, and the platen 1A stops at the position q shown in FIG. The reason why the document table 1A is temporarily stopped in this way is to synchronize the sheet and the image on the photosensitive drum 4.

The stop position q will be further described. In FIG. 3, the position q of the leading edge of the document when the document is paused is
Assuming that the distance between q and a is L4 and the distance from the position where the registration sensor 11 detects the passage of the paper to the transfer portion c is L5, the position where L4 + L2 = L5 is set as the temporary stop position of the platen glass 1. I have. By determining the stop position q in this way, the paper and the image on the photosensitive drum 4 can be synchronized.

By the way, although the driving of the document table 1A is shut off as described above, the driving to the drum / fixing / transport is transmitted as shown in FIG. The pressure roller 10 and the conveying roller pair 8A, 8B are rotating. As a result, the leading end of the sheet conveyed by the pair of conveying rollers 8A and 8B in FIG. 1 depresses the actuator of the registration sensor 11, and a sensor (not shown) such as a photo interrupter or a microswitch detects this.

In response to this signal, the control device 50 as the control means applies a voltage of 24 V to the solenoid 33 as the releasing means to drive the solenoid 33, thereby canceling the clockwise urging force and moving the solenoid lever 32. Rotate counterclockwise. When the solenoid lever 32 rotates counterclockwise in this way, the platen lever 31 whose tip is pressed is released from engagement and rotates clockwise by the urging force of a spring (not shown). Accordingly, as shown in FIG. 7, the distal end is separated from the control ring of the spring clutch gear 23, and the operation stops.

The instantaneous spring clutch gear 23 starts transmitting the drive, and the original table 1A moves again in the D (left) direction. The subsequent movement to the left is an exposure scanning operation of the original. Further, the image of the document created on the photosensitive drum 4 is transferred to a copy sheet with appropriate synchronization, and is conveyed to the fixing in the next step.

On the other hand, at the timing when the sheet is discharged out of the apparatus, the stepping motor 21 rotates forward again. As a result, the one-way clutch interposed between the pair of conveying rollers 8A, 8B, the photosensitive drum 4, and the pressure roller 10 idles, and the rotation thereof is stopped.

As shown in FIG. 8, the platen driving gear 30 rotates forward to move the platen 1A in the C (right) direction. Further, in the sheet feeding system, the swing center gear 26a rotates forward, and the swing gear 26 rotates from the swing gear 26 side to the second gear 27 side. This allows
The paper feeding gear 29 is rotated forward by the second gear 27, and rotates by about half a rotation to a position where the missing tooth portion faces the second gear 27 as shown in FIG. As a result, all the steps of copying one sheet are completed, and the state returns to the state shown in FIG.

As described above, at the time of image reading, the original table 1A returning to the original position is temporarily stopped, and the solenoid 33 is operated according to the signal from the registration sensor 11 to restart the original table 1A. The sheet conveyed to the transfer section is synchronized with the transferred image. This makes it possible to synchronize the image formed by the image forming unit with the sheet without forming a loop.

In the above description, the case where one stepping motor 21 is used as the driving source has been described. However, the present invention does not require a single motor as the driving source. The rotation may be distributed to a first motor responsible for driving the photosensitive drum and fixing / discharging drive, which only needs to provide rotation, and a second motor responsible for driving a document and feeding paper that perform forward and reverse rotation. .
Thereby, a motor with a small rating can be selected. Further, the number of one-way clutches interposed in each part can be reduced, and a configuration having the same function can be formed at substantially the same cost. In addition, since the drum and the fixing parts are operated at the same time as the copying operation is turned on, and it is possible to wait until the paper passes, the heat can be uniformly heated in the fixing device, and a better image quality can be obtained.

Further, in the present embodiment, the solenoid is used as an actuator for giving a trigger for restarting the document table 1A once stopped.
As shown in FIG. 9, means 39 for connecting the registration sensor 11 and the solenoid lever 32 may be provided, and the solenoid 32 may be operated in physical association with the operation of the registration sensor 11.

Thus, in the drive system of the copying machine, it is possible to adopt a configuration in which an electric actuator is not used at all except for the motor as the drive source, and the cost can be further reduced. This naturally leads to improvement in reliability against electrical trouble.

[0052]

As described above, as in the present invention, when reading an image, the original platen returning to the original position on the upper surface of the main body is temporarily stopped, and the sheet conveyed to the transfer unit reaches the predetermined position. By releasing the stop of the document table, the sheet conveyed to the transfer unit and the image to be transferred can be synchronized. As a result, an image can be transferred to a sheet without forming an unreasonable loop on the sheet side even with a postcard and the corresponding thick paper.

Further, it is possible to improve the quality of the margin at the front end of the copy image, the registration, and the like, and there is no rubber mark caused by the paper feed roller.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a copying machine as an example of an image forming apparatus according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a structure of a drive system of the copying machine.

FIG. 3 is a diagram illustrating a stop position of a document table of the copying machine.

FIG. 4 is a diagram showing a state of a drive system when the document table has moved to a home position.

FIG. 5 is a diagram illustrating a state of a drive system when the document table inverted from the stop position temporarily stops.

FIG. 6 is a schematic cross-sectional view of the copying machine when the document table stops once.

FIG. 7 is a diagram showing a state of a drive system when the original table restarts moving.

FIG. 8 is a diagram showing a state of a drive system when the document table returns to an original position.

FIG. 9 is a view showing a structure of a drive system of a copying machine according to a second embodiment of the present invention.

FIG. 10 is a diagram showing a configuration of a conventional copying machine.

[Explanation of symbols]

 Reference Signs List 1A Document table 7 Paper feed roller 8A, 8B Conveyance roller pair 11 Registration sensor 31 Platen lever 33 Solenoid 38 Registration cam 50 Control device

Claims (3)

[Claims] 1. An image reading apparatus comprising: a document table on which a document is placed; and a main body having an image reading unit and an image forming unit and having the document table mounted on a top surface so as to be horizontally movable. An image forming apparatus that returns the original platen to the original position on the upper surface of the main body while passing the platen above the image reading unit, and transfers an image formed by the image forming unit to a sheet A transfer unit, a sheet feeding unit that takes out the sheet from the sheet placement unit when reading an image, a conveyance unit that conveys the sheet taken out from the sheet feeding unit to the transfer unit, and is conveyed by the conveyance unit Detecting means for detecting that the sheet has reached a predetermined position; stopping means for temporarily stopping the platen returning to the original position on the upper surface of the main body when reading the image; stopping of the stopping means Release means for releasing a stop operation; and a document table of the stop means in response to a signal from the detection means at the time of reading the image in order to synchronize the sheet conveyed to the transfer section with the transferred image. An image forming apparatus, comprising: control means for controlling the release means so as to release the stop operation. 2. The image forming apparatus according to claim 1, wherein said conveying means is provided at a position close to said paper feeding means. 3. The image forming apparatus according to claim 1, further comprising a driving unit for moving the document table, wherein the driving unit selectively drives the sheet feeding unit and the conveying unit. apparatus.