JP2007131355A - Sheet feeder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a drive control device having excellent drive control accuracy capable of reducing the rotation-starting force of a chipped tooth gear by avoiding any direct effect of a cam load on the chipped tooth gear with less number of components and a simple configuration. <P>SOLUTION: The chipped tooth gear has a rotational play of a predetermined angle when the chipped tooth gear is rotated by a rotation urging means when the chipped tooth gear starts the drive transmission by a solenoid. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to a sheet feeding apparatus including a rotation transmission device that intermittently presses and feeds a sheet to a pickup sheet feeding roller.

2. Description of the Related Art Image forming apparatuses such as copying machines, printers, and facsimiles are provided with a sheet feeding device for separating stacked sheets one by one and feeding them to an image forming unit.

A conventional sheet feeding apparatus will be described with reference to FIG.

Fig. 1 shows one rotation control of a multi-feed roller using a conventional electromagnetic clutch, and the drive transmission mechanism is operated by intermittently pressing the stacked sheets against the feed roller at a predetermined timing using a missing gear. It is a perspective view shown.

The paper feed roller 101 is fixed to one end of the paper feed shaft 102, and an electromagnetic clutch (not shown) is also fixed to the other end of the coaxial so that driving can be transmitted from a drive source. On the other hand, there is a drive gear 103 to transmit the drive from the drive source, and a missing gear 104 is arranged so as to mesh with the drive gear, and the missing gear 104, the shaft 105, and the pin 106 are coaxial with the missing gear. A cam 107 is provided as a unit. Also, a cam floor 109 pressed against the cam 107 is provided integrally with the middle plate 108 on which sheets are stacked. The sheet feeding middle plate is urged by a middle leaf spring provided on the back surface, and is provided on a frame (not shown) so as to be swingable about a rotation shaft.

In the state before the start of sheet feeding, the cam 107 pushes the sheet feeding middle plate to the lowest position via the cam floor 109, and the pressing force of the cam floor 109 is passed through the rotation center of the cam 107 by the middle leaf spring. (Shown in Figure 2). On the other hand, the toothless gear 104 is pressed in the rotation direction A against the trigger arm 110 biased by a torsion spring (not shown), and is positioned so that the flapper 111a of the solenoid 111 is caught by the locking portion 104a. Yes. At this time, the missing tooth gear 104 is stopped in a state where the tooth missing portion faces the drive gear 103 and the drive is not transmitted to the missing gear 104. In this state, the drive gear 103 is in a rotation free state.

When feeding the solenoid 111 and pulling the flapper 111a when starting feeding, the flapper 111a is disengaged from the locking 104a of the missing gear 104, and the missing gear 104 is slightly rotated in the rotational direction by the urging force of the trigger arm 110. Then, it meshes with the drive gear 103 and starts rotating.

As a result, the missing tooth gear 104 and the eccentric cam 107 are rotated once as a unit, and after one rotation, the locking portion 104a of the missing gear 104 is again caught by the flapper 111a of the solenoid 111 and the rotation of the missing gear 104 is stopped. ing.

Here, when the eccentric cam 107 rotates and the cam floor 109 departs from the arc portion of the eccentric cam 107, the sheet feeding middle plate 108 rotates around the rotation axis by the pressing force of the middle plate spring, and the sheet feeding middle plate The sheet stacked on the top is flipped up until it hits the paper feed roller.

After that, the sheets stacked on the sheet feeding sheet are pressed against the sheet feeding roller 101 by the sheet pressing spring, and then the electromagnetic clutch is energized to be conveyed along with the rotation of the sheet feeding roller 101.

In the above-described conventional sheet feeding device, the biased gear 104 is used for the torsion spring and the trigger arm 110 for biasing, but there is also an independent tension spring.

In the above-described conventional sheet feeding device, a configuration in which the missing gear 104 and the eccentric cam 107 are integrated is used. Thus, in a drive control device using a missing tooth gear, an electromotive force for rotating the missing tooth gear until it engages with the driving gear is required.

However, in the conventional drive control device as described above, the middle plate spring that biases the rise of the middle plate needs a biasing force sufficient to press the stacked sheets against the feeding roller, This strong urging force is also pressed against the cam 107 via the cam floor 109, and a resistance moment of the rotational load is generated between the cam 107 and the cam floor 109 by a strong frictional force. Thus, since the missing tooth and the cam are integrated, the missing tooth gear 104 is directly subjected to the load from the cam 107, and therefore, it is necessary to have a strength more than necessary for the electromotive force.

However, this strong rotational force causes various problems as follows. First, since it is necessary to increase the locking force for locking the toothless gear against this strong rotational force, to release the strong locking force, the solenoid should be enlarged or newly A release part had to be provided. As a result, the structure of the entire apparatus is complicated and large. In addition, when the lock is released and the toothless gear and the drive gear mesh with each other due to this strong rotational force, an excessive force is applied to the drive gear. For this reason, the rotational speed increased at that moment.

This sudden increase in the rotational speed of the drive gear affects all gears that are linked to the drive gear. For example, in the general case, when the drive gear is linked to the conveyance roller that directly conveys the sheet to the transfer unit In this case, the rotation speed of the conveying roller is increased and the sheet is pushed into the transfer portion, causing image blurring and the like, and the image forming quality is deteriorated. In addition, due to this strong rotational force, a strong impact is generated when locking and releasing the lock, and the noise is increased. Conventionally, grease is applied between the cam and the cam floor or an expensive special material is used for the cam or the cam floor so as to reduce the rotational load of the intermediate plate cam. Further, as shown in FIG. 3 (Japanese Patent Laid-Open No. 08-225167), some cam floors are provided with freely rotatable rollers 112. As a result, the cost was high. Further, in the conventional apparatus, when the eccentric cam rotates and the cam floor is detached from the arc portion of the eccentric cam, the sheet feeding intermediate plate is instantaneously rotated around the rotation axis by the pressing force of the intermediate plate spring, and vigorously. Is pushed up until it hits the paper feed roller. However, the paper feeding plate that jumps up and hits the paper feed roller and rebounds, causing the paper feeding failure without applying the appropriate paper feeding pressure, and causing image defects such as image pitch unevenness due to shake due to the impact of the collision. There was a problem of causing noise and noise during feeding.

Therefore, the present invention has been made in view of the above problems, and reduces the rotational force of the missing gear by preventing the cam load from directly affecting the missing gear with a simple configuration with a small number of parts. An object of the present invention is to provide a drive control device with excellent drive control accuracy.
Also, after the eccentric cam rotates, the movement of the cam floor is controlled according to the rotation of the cam to control the jumping of the sheet placing plate to prevent the occurrence of blurring and noise due to the impact of the collision, and to prevent the sheet feeding failure. The purpose is to prevent.

In order to solve the above-described problem, the present invention provides a sheet stacking plate that is loaded with sheets and is rotatably supported between a feeding position and a standby position, and the sheet stacking plate from the standby position to the feeding position. An elastic member for urging the sheet, a feeding roller for feeding out the sheets stacked on the sheet stacking plate at a feeding position by the urging force of the elastic member, and a missing tooth portion lacking a predetermined portion of teeth. A toothless gear for transmitting the rotation of the sheet stacking plate, a cam drive shaft for transmitting drive from the toothless gear, a solenoid for controlling the rotation of the toothless gear, and the solenoid. In the sheet feeding device that feeds a sheet having a rotation urging means that rotates the missing tooth gear by a predetermined angle in a rotation direction when the rotation stop of the missing tooth gear is released, the missing tooth gear is , Driven by the solenoid When starting a transmission, when the toothless gear is rotated by the biasing force of said rotation biasing means, wherein the segment gear is configured to have a rotational backlash of a predetermined angle.

According to the sheet feeding device having such a configuration, by reducing the number of parts and making the cam load not directly affect the missing gear with a simple configuration, the rotational force of the missing gear is reduced, A drive control device with excellent drive control accuracy can be provided.

An embodiment of the present invention will be illustratively described below with reference to the drawings. FIG. 4 is a schematic configuration diagram of a sheet feeding device using the drive control device according to the embodiment of the present invention. First, the configuration of the sheet feeding apparatus will be described with reference to FIG.

The sheet feeding device intermittently presses the sheets stacked on the sheet stacking plate at a predetermined timing to the sheet feeding roller, and uses an electromagnetic clutch to control the rotation of the sheet feeding roller at a predetermined timing. This is a sheet feeding device for separating the fed sheets one by one and feeding them to the image forming unit.

In this sheet feeding apparatus, the sheet stacking plate 1 is stacked and supported so as to be rotatable between the feeding position and the standby position, and the sheet stacking plate 1 is biased from the standby position to the feeding position. An elastic member (not shown), a feeding roller 2 for feeding the sheet in pressure contact with the sheets stacked on the sheet stacking plate at a feeding position by the urging force of the elastic member, and the feeding roller 2 The electromagnetic clutch 3 is connected intermittently at a predetermined timing through the paper feed shaft 11 and connected to a driving source to control the rotation, the cam floor 12 integrated with the sheet stacking plate 1 and the cam floor 12 through the eccentric cam 4 for moving the sheet stacking plate 1 to the standby position against the urging force of the elastic member, and a missing tooth portion lacking teeth at one place on the outer periphery, To transmit / cut off the drive to the eccentric cam 4 The toothless gear 5 and one end serve as the center of rotation of the eccentric cam 4 and are connected to the eccentric cam 4 to transmit the drive. The other end serves as the center of rotation of the toothless gear 5 and drives from the toothless gear 5. The cam drive shaft 6 to be transmitted, the solenoid 7 for controlling the rotation of the toothless gear, and when the rotation stop of the toothless gear 5 is released by the solenoid 7, the toothless tooth is caused by a torsion spring (not shown). A rotation urging arm 8 that rotates the gear 5 in the rotation direction by a predetermined angle, and is connected to a drive source, facing the missing tooth portion of the missing gear 5 when the rotation of the missing tooth gear 5 is stopped. And a drive gear 9 that meshes with the toothed portion of the toothless gear 5 to transmit the drive when the stoppage of rotation of the toothless gear 5 is released by the solenoid 7.

FIG. 5 is an enlarged perspective view showing a drive unit of the sheet feeding apparatus according to the present invention. This will be described in more detail based on FIG. The toothless gear 5 has a toothed portion that can mesh with the drive gear 9, and transmission / cutoff of driving is controlled by the solenoid 7 according to the position of the toothless portion of the toothless gear 5. Yes. The toothless gear 5 is provided with a locking portion 5a that is locked by a flapper 7a of the solenoid 7 to stop rotation, and a biasing portion 5b that is biased by the rotation biasing arm 8 to start rotation. It has been. When drive transmission is started by the solenoid 7, the flapper 7a of the solenoid 7 is separated from the locking portion 5a of the toothless gear 5, and the toothless gear 5 is rotated by the biasing force of the rotary biasing arm 8. The toothed part of the initial toothless gear 5 is engaged with the drive gear 9 by rotating at a predetermined angle in the direction.

The configuration shown in FIG. 5 is shown in a side view in FIG. However, in FIG. 6, it is shown separately for easy understanding. This will be described with reference to FIG. The cam drive shaft 6 has a toothless gear side that is perpendicular to the shaft center of the cam drive shaft 6 and is integral with the cam drive shaft 6. A spring pin 10 for transmitting to the shaft 6 is provided. The toothless gear 5 is provided with a groove 5c for storing the spring pin 10 so that the drive is transmitted to the cam drive shaft via the spring pin 10. When drive transmission is started by the solenoid 7, the flapper 7a of the solenoid 7 is separated from the locking portion 5a of the toothless gear 5, and the toothless gear 5 is rotated by the biasing force of the rotary biasing arm 8. The partial gear 5 has a constant rotation free angle so that the partial gear 5 is free to rotate without transmitting drive to the spring pin 10 when rotating in the direction by a predetermined angle. A predetermined free space 5c1 is provided between the pin storage groove 5c and the spring pin 10 in the rotational direction of the toothless gear 5.

Next, the outer peripheral shape of the eccentric cam 4 will be described with reference to FIG. Further, the outer peripheral shape of the eccentric cam 4 is integrally formed with the sheet feeding stacking plate while the eccentric cam rotates when the sheet stacking plate is moved from the sheet feeding position to the standby position at the portion contacting the cam floor 12. A downward curve portion in which the radius from the rotation center gradually increases so as to be pushed down to the cam floor, and after the sheet stacking plate has reached the standby position, the solenoid flapper is engaged with the intermittent gear. A large arc portion whose center is the rotation center of the eccentric cam, and the missing gear is caught by a flapper of the solenoid and rotated so that the eccentric cam rotates according to the rotation of the missing gear until it is caught by the portion. After the stop, the eccentric cam has a substantially ω-shaped portion so that the eccentric cam continues to rotate at a predetermined angle by the rotational biasing moment generated by the inertia force and the pressing force from the cam floor. When the eccentric cam is moved from the standby position to the sheet feeding position before and after the stop position, the eccentric cam jumps from the cam floor when the eccentric arc moves around the rotation center of the eccentric cam and the sheet stacking plate. The eccentric cam so that the sheet is pressed against the sheet feeding roller at a predetermined time when the sheet stacking plate is moved to the sheet feeding position. Is configured as a non-acting portion so as not to be pressed against the cam floor. Further, the eccentric cam is characterized in that the radius of the large arc portion is slightly larger than the radius of the stop arc portion.

Since this embodiment according to the present invention is configured as described above, its operation will be described in the following six stages.

First, the sheet stacking plate 1 is moved from the sheet feeding position to the standby position, and when reaching the standby position, until the flapper 7a of the solenoid 7 is hooked on the locking portion 5a of the missing gear 5, the following 3 Divide into stages.

The first stage is a stage in which the eccentric cam 4 rotates according to the rotation of the toothless gear 5. This stage is a lowering stage of the sheet stacking plate 1. As shown in FIG. At this stage, the eccentric cam 4 is first pushed by the descending curved portion against the cam floor 12 and gradually reaches a large arc. Next, the toothed portion of the toothless gear 5 is disengaged from the drive gear 9 after passing the large arc portion.

The second stage is a stage until the rotation of the missing gear 5 stops after the meshing of the missing gear 5 and the drive gear 9 is disengaged. When the point pressed against the cam floor 12 of the eccentric cam 4 in the first stage has passed the large arc portion, the toothed portion of the toothless gear 5 is disengaged from the drive gear 9, and the rotation The biasing arm 8 starts to apply a biasing force to the toothless gear 5. After the disengagement gear 5 and the drive gear 9 are disengaged, the disengagement gear 5 continues to rotate with the inertial force and the urging force of the rotation urging arm 8. When the missing tooth gear 5 reaches a predetermined position, the flapper 7a of the solenoid 7 is caught by the engaging portion 5a of the missing tooth gear 5, and the rotation of the missing tooth gear is stopped.

Third stage, from stopping of the toothless gear 5 to stopping of the eccentric cam 4 (the sheet stacking plate 1 reaches the standby position). FIG. 9 shows a state in which the second stage ends and the third stage starts. When the second rotation of the toothless gear in the second stage stops, the acting direction of the pressing force from the cam floor 12 to the eccentric cam 4 deviates from the rotation center of the eccentric cam 4, so that the eccentric cam Rotation bias moment is generated in 4. From this, the eccentric cam 4 can continue to rotate at a predetermined angle vigorously with the inertial force and the rotational biasing moment generated by the pressing force from the cam floor 12. At this time, the cam drive shaft 6 and the spring pin 10 integrated with the eccentric cam 4 also rotate at a predetermined angle together with the rotation of the eccentric cam 4, and the free tooth gear 5 has the free gear. A rotating space 5c1 (FIG. 6) is created. At this stage, the sheet stacking plate 1 also reaches the stop position and stops. The state after this stage is shown in FIG.

Next, when the sheet stacking plate 1 is moved from the standby position to the sheet feeding position, the following two stages are divided.

When the drive transmission is started by the solenoid 7 in the fourth stage, when the solenoid 7 is operated to start the next feeding until the toothed portion of the toothless gear 5 is engaged with the drive gear 9 from the start of rotation of the toothless gear 5 In addition, when the flapper 7a of the solenoid 7 is separated from the locking portion 5a of the toothless gear 5, there is a free rotation space 5c1 formed in the third stage, so that the toothless gear 5 is separated from the eccentric cam 4. Without being subjected to the load, the rotating biasing arm 8 starts to rotate smoothly. After the toothless gear 5 rotates by a predetermined angle from the rotation biasing arm 8, the toothed portion of the toothless gear 5 reaches the meshing position with the drive gear 9. FIG. 10 shows a state where the fourth stage is completed.

In the fifth stage, the toothed portion of the toothless gear 5 starts from meshing with the drive gear 9 until the sheet stacking plate 1 reaches the paper feed position where the sheet stacking plate 1 is pressed against the paper feed roller 2, and the toothed portion of the toothless gear 5 is the drive gear. When meshed with 9, the toothless gear 5 continues to rotate by the drive gear 9. Then, the eccentric cam 4 starts to rotate with respect to the rotation of the partial gear 5 via the cam drive shaft 6 and the spring pin 10. At this stage, the reaction direction of the reaction force through the cam floor 12 from the biasing spring of the sheet stacking plate 1 to the eccentric cam 4 approaches the rotation center of the eccentric cam 4, so that the sheet stacking The rise of the plate 1 rises according to the rotation of the eccentric cam 4 and does not jump up, making it possible to prevent the occurrence of blurring and noise due to impact. FIG. 11 shows the fifth stage.

Finally, the sixth stage is a stage in which the sheet stacking plate 1 is at the sheet feeding position. When the rotation of the eccentric cam 4 reaches a position facing the cam floor 12 of the non-acting portion, the sheet stacking plate 1 reaches a position where it is pressed against the paper feed roller 2. From now on, the eccentric cam 4 is separated from the cam follower 12 until the descending curved portion of the eccentric cam 4 faces the cam floor 12. At this stage, the eccentric cam 4 is not pressed against the cam floor 12, and the sheet stacking plate 1 integrated with the cam floor 12 is also pressed by the eccentric cam 4 through the cam floor 12. It will be in the state which has not received. The sheet stacking plate 1 is urged by the urging member and is pressed against the sheet feeding roller 2 so that a predetermined sheet feeding pressure can be obtained between the sheet stacking plate 1 and the sheet feeding roller 2. At this stage, the range in which the eccentric cam 4 is not pressed against the cam flow 12 varies depending on the height of the sheet bundle loaded on the sheet stacking plate 1.

  The sheet feeding apparatus according to the present invention described above can be widely applied to a wide variety of image forming apparatuses such as copying machines as well as image forming apparatuses such as printers.

It is a perspective view which shows the structure of a prior art. It is sectional drawing explaining a prior art. It is a perspective view which shows an example of a prior art. 1 is a perspective view illustrating a configuration of an embodiment of a sheet feeding apparatus according to the present invention. FIG. 3 is an enlarged perspective view showing a configuration of a sheet feeding device embodiment driving unit according to the present invention. FIG. 4 is a side view illustrating a configuration of a driving unit of a sheet feeding device according to the present invention. It is a side view of the eccentric cam used for the sheet feeding apparatus according to the present invention. FIG. 6 is a perspective view illustrating a lowering stage of a sheet stacking plate. FIG. 6 is a side view showing a state where the second stage is finished and the third stage is started. FIG. 10 is a side view showing a state after completion of the fourth stage. FIG. 10 is a perspective view showing a raised state of a sheet stacking plate that is a fifth stage.

Explanation of symbols

Sheet loading plate Feed roller Electromagnetic clutch Eccentric cam Missing gear Cam drive shaft Solenoid rotation energizing arm drive gear Spring pin Feed shaft Cam floor

Claims (1)

A sheet stacking plate that is stacked and supported so as to be rotatable between a feeding position and a standby position;
An elastic member for urging the sheet stacking plate from a standby position to a feeding position;
A feeding roller for feeding out the sheets stacked on the sheet stacking plate at a feeding position by a biasing force of the elastic member;
A missing tooth gear for transmitting rotation of the sheet stacking plate;
A cam drive shaft to which drive is transmitted from the toothless gear;
A solenoid for controlling the rotation of the toothless gear;
In the sheet feeding device that feeds a sheet provided with a rotation urging unit that rotates the missing tooth gear by a predetermined angle in a rotation direction when the solenoid stops the rotation of the missing tooth gear.
The partial gear has a rotation play of a predetermined angle when the partial gear is rotated by the urging force of the rotation urging means when drive transmission is started by the solenoid. The sheet feeding device is characterized.

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