JP4136186B2 - Image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sheet conveying apparatus that conveys and separates sheets with a single motor in a serial type image forming apparatus.
[0002]
[Prior art]
A serial type image forming apparatus scans a carriage having a recording unit in a main scanning direction to record an image, and intermittently conveys the sheet in a direction (sub-scanning direction) perpendicular thereto. An image is recorded on the entire surface.
[0003]
In such a configuration, the resolution in the main scanning direction is directly determined by the resolution of the recording unit, whereas the connecting portion of the images in the sub-scanning direction is determined by the accuracy of sheet conveyance. That is, the continuity of the image in the sub-scanning direction is determined by factors different from those in the main scanning direction, so that it is conspicuous, and it is preferable that the conveying means (generally, the conveying roller) is directly connected to the driving motor and precisely controlled.
[0004]
On the other hand, in such an apparatus, the sheets stacked on the feeding unit are separated and fed by the feeding unit, and the skew is corrected and conveyed to the recording unit by a conveying unit (generally a roller, hereinafter referred to as a conveying roller). When a roller (hereinafter referred to as a “feed roller”) is used as the feeding means, the feed roller is driven only when the sheet is separated and fed, and otherwise it needs to be stopped, and further separated from the sheet. It is preferable. Therefore, in order to drive both the conveying roller and the feeding roller with a single drive motor, a driving intermittent means is required.
[0005]
Further, when the sheet is conveyed after correcting the skew of the sheet, the conveying roller must be rotated in the reverse direction and then rotated in the normal direction while the feeding roller is always rotated in the forward direction. That is, when the drive motor is driven in either the forward or reverse direction, the feed roller needs to be configured to transmit the forward drive. Conventionally, as this configuration, the drive transmission mechanism to the feeding roller when the motor is rotating forward and reverse is switched by the drive switching means, and the number of gears used for these drive transmission mechanisms is one sheet. Or, it is realized by making the odd number different and interposing a one-way clutch in both of the drive transmission systems.
[0006]
In the above-described configuration, the skew of the sheet is corrected by abutting the sheet on the conveying roller that is reversed by the feeding roller. Next, in order to carry the sheet, the drive motor is reversed and rotated forward, and the sheet is held by the carrying roller. Here, when the sheet is bent due to an excessive feeding amount of the feeding roller during skew correction, the holding is easily completed by the elastic restoring force. However, when the stiffness of the sheet is strong, slippage is corrected between the feeding roller and the sheet, and skew correction is performed. Therefore, only the frictional force between the conveying roller and the sheet is included in the nip. It becomes. Therefore, when considering various paper types, environments, and durability, it is impossible to guarantee the gripping with this alone, and it is necessary to push the feeding roller. For this reason, the feeding roller is configured to continue normal rotation even after the conveyance roller starts normal rotation.
[0007]
[Problems to be solved by the invention]
However, in the above configuration, when a pendulum type that can be configured at a relatively low cost is used for the one-way clutch, a time lag occurs because the pendulum moves when the rotation direction of the transport roller changes from reverse to normal. Sometimes the feed roller still doesn't rotate. For this reason, there is a problem in that the leading edge margin varies, or the left and right difference occurs in the holding timing, resulting in skew. In order to avoid this, there is a method of using a spring clutch or a needle type one-way clutch with a small time lag, but there is a problem in that the production cost is high.
[0008]
Accordingly, the present invention provides a spring clutch or a needle type one-way clutch that is quickly switched only to drive transmission during forward rotation of a drive motor that does not allow a time lag in an image forming apparatus having a drive switching means that requires two forward and reverse one-way clutches. It is an object of the present invention to provide an image forming apparatus that is relatively inexpensive and has stable conveyance performance.
[0009]
[Means for Solving the Problems]
In order to solve the above-described problems, an image forming apparatus according to the present invention includes a feeding roller that separates and feeds stacked sheets, a conveying roller that conveys the sheet, and a forward and reverse connection that is directly connected to the conveying roller. A driving motor that rotates, a driving intermittent means that selectively transmits driving from the driving motor to the feeding roller, and the feeding roller that rotates in the conveying direction regardless of the rotation direction of the driving motor (hereinafter referred to as forward rotation). The drive switching means uses a spring clutch for the one-way clutch that transmits the drive when the drive motor rotates in the forward direction, and the one-way that transmits the drive when the drive motor rotates in the reverse direction. The clutch is of a pendulum type, and the number of gears used for forward and reverse drive transmission is different from one to odd.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of an image forming apparatus according to the present invention will be described with reference to the drawings. 1 is an overall configuration diagram of the image forming apparatus according to the present embodiment, FIG. 2 is a diagram illustrating a positional relationship in the depth direction of the apparatus, FIG. 3 is a diagram illustrating a state of the drive switching unit during normal rotation, and FIG. Is a diagram for explaining the state of the drive switching means during reverse rotation, FIGS. 5 to 10 are diagrams for explaining the operation of the drive intermittent means, FIG. 5 is during recording, FIG. 6 is during transition to the feeding trigger position, 7 is a drawing trigger position, FIG. 8 is a recovery position, and FIG. 9 and FIG. The image forming apparatus according to the present embodiment will be described using a spring clutch as a one-way clutch during normal rotation of the drive motor.
[0011]
(overall structure)
The image forming apparatus shown in FIG. 1 is a serial ink jet recording apparatus. A sheet mounting table 1 on which sheets P are stacked is attached to the rear portion of the apparatus so as to be rotatable with respect to the apparatus main body. The sheet placing table 1 is configured to be moved up and down by a cam (not shown) attached to the feeding roller 2, and in a normal standby state, the sheet placing table 1 is lowered as shown in FIG. Yes.
[0012]
When recording is started, a drive interrupting means, which will be described later, starts driving transmission to the feed roller 2 and starts rotating in the forward direction (clockwise direction in the figure, hereinafter referred to as forward rotation). Then, the cam attached to the feeding roller 2 also rotates to raise the sheet placing table 1 so that the sheet P and the feeding roller 2 come into contact with each other and the conveyance of the sheet P is started.
[0013]
A separation claw 3 is provided at the lower part of the sheet mounting table 1, and the sheet is separated and fed by the cooperation of the feeding roller 2 and the separation claw 3, and is conveyed to the conveyance roller 6 by the lower guide 4 and the upper guide 5. It is guided to the nip portion of the roller 7. As will be described later, the conveying roller 6 first rotates in the reverse direction (counterclockwise direction in the figure, hereinafter referred to as reverse rotation) to correct skewing, and then rotates forward to further convey the sheet P.
[0014]
A platen 8 is provided at a position facing the recording unit 9 that forms an image on the sheet P, and supports the back side of the sheet P to maintain the interval between the recording unit 9 and the sheet P. The recording means 9 has a recording head 9b having a plurality of ink discharge ports arranged in a line in the conveyance direction of the sheet P, and records one line image while scanning the recording head 9b in a direction orthogonal to the conveyance direction (main scanning direction). To do. Each time the recording unit 9 records an image of one line, the conveying roller 6 conveys the sheet P for one line, and this is repeated to record an image on the front surface of the sheet P. The sheet P on which an image is recorded by the recording means 9 is sandwiched between the discharge roller 10 and the spur 11 and discharged and stacked on the discharge tray 12 while maintaining flatness.
[0015]
Next, the positional relationship in the depth direction of the apparatus will be described with reference to FIG. The sheet P is set on the sheet reference 1a on the front side of the sheet placing table 1 in the drawing. This is because the recorded matter is usually drawn with the sheet left-justified, and the movement distance of the carriage 9a is shortened (throughput improvement). In addition, a preliminary ejection position 13a is provided at the pre-recording standby position where the recording means 9 is removed from the front of the sheet in the drawing. This is because, in the case of ink jet recording, it is necessary to perform preliminary ejection outside the sheet at the time of line feed or page break in order to remove a recording defect by drying the recording head 9b. Therefore, the preliminary discharge position 13a is also arranged in the vicinity of the sheet reference 1a for improving the throughput.
[0016]
On the front side of the preliminary discharge position 13a, there is a feeding trigger position 13b to be described later. The feeding trigger position 13b refers to the position of the carriage 9a when the sheet feeding by the feeding roller 2 is started. Accordingly, the drive transmission mechanism 15 for transmitting the drive to the feed roller 2 is also located in the vicinity thereof. Further, there is a recovery and cap position 13c on the near side in the figure, and a recovery unit 13d is arranged in the vicinity thereof. That is, at the time of recording, they are arranged from the sheet P side in the order of the required number of times.
[0017]
Since the preliminary discharge position 13a, the feeding trigger position 13b, and the recovery and cap position 13c are located on the front side in the figure, the drive motor 14 and the drive system of the transport roller 6 are on the opposite side of the sheet P. Is arranged. As described above, since the feed accuracy of the transport roller 6 is important, no drive on / off means such as a clutch is arranged in the drive transmission from the drive motor 14. Similarly, the gear 6a of the conveying roller 6 has a large number of teeth and therefore has a large diameter in order to improve feeding accuracy. For this reason, the gear 6a protrudes from the sheet surface, and thus is disposed outside the movement range of the carriage 9a. On the other hand, since the drive transmission mechanism 15 for the feeding roller 2 is disposed on the front side of the sheet as described above, the feeding roller 2 is configured to transmit the drive via the conveying roller 6.
[0018]
Next, the vertical direction will be described. The preliminary discharge port at the preliminary discharge position 13a, the recovery unit 13d, and the like are disposed below the sheet conveying surface because they need to be at the opposing portion of the recording head 9b. Considering replacement of the recording head 9b and an ink tank (not shown), the front surface of the carriage 9a (left side in FIG. 1) is preferably an opening. For this reason, it is desirable to arrange the drive system including the movement guide of the carriage 9a on the back surface (right side in FIG. 1) of the carriage 9a. Therefore, it is desirable that the drive transmission mechanism 15 be arranged below the carriage 9a as well as the recovery unit 13d.
[0019]
(Drive transmission mechanism)
Next, the drive transmission mechanism 15 will be described. The drive transmission mechanism 15 includes drive switching means for rotating the feed roller 2 in one direction regardless of the rotation direction of the drive motor 14, and drive intermittent means for selectively transmitting drive from the drive motor 14 to the feed roller 2. have. Each will be described below.
[0020]
(Drive switching means)
FIG. 3 is a developed view of the drive switching means when the transport roller rotates in the forward direction, and FIG. 4 is a developed view of the drive switch means when the transport roller rotates in the reverse direction. The actual three-dimensional arrangement is different. The drive switching means supports various gears by the frames 16 and 17.
[0021]
In FIG. 3, an input gear 18 to the drive switching means and an output gear 19 to the recovery system are attached to the transport roller shaft 6b. As described above, the transport roller shaft 6b is directly connected to the drive motor 14 to rotate forward and reverse, and when it rotates forward, it rotates in the direction of arrow A in FIG. The input gear 18 meshes with the large-diameter gear 20a of the reduction sun gear 20 and rotates in the direction of arrow B. The spring clutch input gear 21 meshes with the small-diameter gear 20b of the reduction sun gear 20.
[0022]
A spring clutch output gear 22 is arranged coaxially with the spring clutch input gear 21, and a spring clutch 23 is stretched between them. The spring clutch 23 is configured to transmit drive only when rotating in the direction of arrow A, and the spring clutch input gear 21 and the spring clutch output gear 22 rotate in the same direction in synchronization. The spring clutch output gear 22 meshes with the clutch trigger gear 24 and rotates it in the direction of arrow B.
[0023]
The drive transmitted to the clutch trigger gear 24 is intermittently transmitted to the clutch gear 26 via the clutch separation spring 25 and is transmitted to the output gear 27 to the feeding roller 2. This driving interruption is performed by driving interruption means described later.
[0024]
In FIG. 4, the transport roller shaft 6b and the input gear 18 rotate in the reverse direction, that is, in the direction of arrow B, and the decelerating sun gear 20 rotates in the direction of arrow A. A pendulum arm 28 supporting the planetary gear 29 is rotatably fitted to the decelerating sun gear 20, and the planetary gear 29 is always meshed with the small-diameter gear 20b and has a side pressure spring 30 between the planetary gear 29 and the pendulum arm 28. To give a rotational load. As a result, the pendulum arm 28 swings when the decelerating sun gear 20 reverses, and the spring clutch output gear 22 and the planetary gear 29 mesh to transmit the drive in the direction of arrow A. During the forward rotation described above, the planetary gear 29 is separated from the spring clutch output gear 22, so that the drive is not transmitted.
[0025]
When the planetary gear 29 transmits drive to the spring clutch output gear 22, the spring clutch output gear 22 rotates in the opposite direction to the spring clutch input gear 21 (not shown, but the spring clutch input gear 21 is actually the same as in FIG. Meshing with the small-diameter gear 20b). However, since the spring clutch 23 rotates in a direction in which the drive is not transmitted, the drive from the spring clutch input gear 21 to the spring clutch output gear 22 is not transmitted.
[0026]
In this way, even when the transport roller 6 rotates in the reverse direction, the same rotational drive in the direction of arrow B as in the forward rotation is transmitted to the clutch trigger gear 24, that is, the feed roller 2 is always driven in the forward direction. Communicated.
[0027]
When feeding using the drive switching means configured as described above, the transport roller 6 is first rotated in the reverse direction and the feed roller 2 is rotated in the normal direction by the pendulum arm 28. Thus, even when skew occurs in the fed sheet P, skew correction can be performed by abutting the leading end of the sheet against the nip between the transport roller 6 and the transport roller 7. At this time, the excess feeding amount is eliminated by causing the sheet P to bend, or depending on the stiffness of the paper or the feeding force of the feeding roller 2 to cause a slip between the feeding roller 6 and the sheet P. Further, the sheet leading edge position is detected by the sheet leading edge sensor 5a, and the extra feed is controlled to about 3 mm.
[0028]
When the predetermined amount is excessively fed, the rotation direction of the drive motor 14 is switched to cause the conveyance roller 6 to rotate forward, and the sheet P can be held in the conveyance roller 6. At this time, if the sheet P is bent, it can be easily held by the repulsive force. However, when the excess feeding amount has been eliminated by the sliding between the conveying roller 6 and the sheet P, This repulsive force cannot be obtained.
[0029]
However, in the above configuration, when the pendulum arm 28 is separated from the spring clutch output gear 22, the drive to the feeding roller 2 is immediately transmitted by the spring clutch 23. 2 can also start driving. Therefore, the sheet P can be boosted by the feeding roller 2 without causing a time lag, and the sheet P can be reliably and accurately conveyed without causing a deviation in the leading end position or causing a difference in the left and right gripping and skewing again. Can be started.
[0030]
In the present embodiment, the spring clutch 23 is used as the clutch for switching from reverse rotation to forward rotation.However, the present invention is not limited to this, and similarly, a needle-type one-way clutch that is quickly switched is used. Also good.
[0031]
(Drive intermittent means)
Next, the drive interrupting means will be described with reference to FIGS. The driving intermittent means is a means for selectively transmitting the driving from the clutch trigger gear 24 to the feeding roller 2 by connecting and disconnecting the clutch gear 26. As described above, the clutch trigger gear 24 is configured to rotate normally regardless of the rotation direction of the drive motor 14 and the conveying roller 6.
[0032]
The clutch trigger gear 24 is arranged coaxially with the clutch trigger gear 24, and is supported so as to be movable in the separating direction with respect to the clutch gear 26 formed with the same number of teeth. Sawtooth-like tooth surfaces are formed on the opposing end surfaces of the clutch trigger gear 24 and the clutch gear 26, and the surfaces that contact when transmitting the rotation are inclined at about 5 degrees with respect to the vertical. As a result, the clutch can be surely separated, and the separation force due to transmission can be reduced to minimize the urging force of the stroke absorbing spring 33, which will be described later, further contributing to the reduction of the operating force of the actuator. . In addition, the surface opposite to the tooth surface is formed as inclined as possible so as not to transmit the drive force, which increases the tooth strength and contributes to the separation of the clutch. The probability of contact is lowered.
[0033]
The clutch trigger gear 24 is provided with a clutch separation spring 25 and urges the clutch gear 26 in the separation direction. The clutch separation spring 25 is to keep the clutch trigger gear 24 and the clutch gear 26 from meshing, and the link member 31 and the slide member 32 also maintain the normal position by the clutch separation spring 25.
[0034]
An output gear 27 is engaged with the clutch gear 26, and the drive is transmitted to the feeding roller 2 coaxial therewith. Further, the output gear 27 has a not-shown gear that engages with the clutch trigger gear 24 at the end, and when the missing tooth portion and the clutch trigger gear 24 correspond, the feeding roller 2 is in a standby state. Incorporated in phase alignment. The output gear 27 and the gear on the shaft of the feeding roller 2 have the same number of teeth, and drive is transmitted without being decelerated.
[0035]
The link member 31 is rotatably supported. One end of the link member 31 is in contact with the clutch trigger gear 24, and the clutch trigger gear 24 is moved and meshed with the clutch gear 26 by rotating. The link member 31 is connected to a slide member 32 that is movable only in one direction (the direction of arrow C in FIG. 5), and the link member 31 is rotated by sliding movement. A stroke absorbing spring 33 is disposed between the link member 31 and the slide member 32, and is urged away from each other. Further, a locking portion 32a is provided at the tip of the slide member 32, and is configured not to be separated from the link member 31 by a predetermined amount or more.
[0036]
The slide member 32 is operated in conjunction with the operation of the carriage 9a. However, it is difficult to configure the carriage 9a to directly act on the slide member 32 due to a configuration problem inside the image forming apparatus. Therefore, an actuator 34 is provided, and a part of the carriage 9a is configured to act on the slide member indirectly by pressing the actuator 34, thereby serving as a feed trigger.
[0037]
The actuator 34 is configured to be movable in the same direction (arrow D direction) as the scanning direction of the carriage 9a, and is provided with a projecting contact portion 34a with the carriage 9a. The actuator 34 is biased toward the back of the apparatus (left side in the figure) by a biasing means (not shown) and is stopped by a stopper (not shown). By urging in this way, the actuator 34 can return to the standby position when the carriage 9a moves to the back side of the apparatus. Conversely, when the drive interrupting means is operated, if the carriage 9a is positioned on the front side of the apparatus with respect to the preliminary discharge position 13a, the actuator 34 is also positioned on the near side, and the biasing means is extended.
[0038]
A latch member 35 that contacts the cam 32 b of the slide member 32 is attached to the actuator 34. A contact portion 35a that contacts the cam 32b of the latch member 35 is formed on a slope. The latch member 35 has a shaft portion 36 attached to the elongated round hole 35b, and is movable in the moving direction of the actuator 34 by the length of the elongated round hole and is also rotatable. Further, the latch member 35 is biased by the spring 37 toward the back of the device (left side in FIG. 5) and toward the slide member 32 (clockwise direction in FIG. The engaging portion 35c provided on the back surface of the latch member 35 is regulated up and down by the convex portions 34b and 34c formed on the actuator 34, and is stably stopped at this position.
[0039]
FIG. 5 shows a case where the carriage 9a is located at the preliminary ejection position 13a (see FIG. 2) or the recording position, and the drive interrupting means is not operating. Accordingly, when the conveyance roller 6 is rotationally driven in this state, the clutch trigger gear 24 rotates in the forward direction, but the drive is not transmitted to the clutch gear 26. Similarly, the output gear 27 has a toothless portion facing the clutch trigger gear 24, and the drive is not transmitted. For these reasons, the feeding roller 2 is stopped without rotating.
[0040]
FIG. 6 shows the carriage 9a being moved to the feeding trigger position 13b. When the carriage 9a approaches the feeding trigger position 13b from the preliminary discharge position 13a, the carriage 9a and the contact portion 34a of the actuator come into contact with each other, and the actuator 34 moves together with the carriage 9a to the front side of the apparatus (right side in the drawing) to latch. The contact portion 35a of the member and the cam 32b of the slide member 32 are in contact with each other at the inclined surfaces. Although an upward left force is applied to the latch member 35, the oblong hole 35b and the shaft portion 36 are in contact with each other in the left direction, and the engaging portion 35c and the convex portion 34b are in contact with each other in the upward direction. At this time, no load is applied to the spring 37 of the latch member 35, and nothing is acting. Only the position of the latch member 35 is determined.
[0041]
On the other hand, a force acts on the slide member 32 in the lower right direction, and the slide member 32 moves in the direction of arrow C according to the guide. The movement is transmitted to the link member 31 via the stroke absorbing spring 33, and the link member rotates in the clockwise direction in the figure. Further, the movement is transmitted to the clutch trigger gear 24, and the clutch trigger gear 24 moves against the urging force of the clutch separating spring 25. When the carriage further moves to the front side of the apparatus, it reaches the feeding trigger position 13b.
[0042]
FIG. 7 is a view when the carriage 9a is positioned at the feeding trigger position 13b. At this time, the contact between the contact portion 35a of the latch member 35 and the cam 32b of the slide member 32 reaches the apex, and the amount of movement of the slide member becomes the highest point. The clutch trigger gear 24 also completely contacts and meshes with the clutch gear 26 to transmit the drive to the feeding roller 2.
[0043]
The pressing amount at this time is set to be larger than the actual gap. This is to ensure meshing even if there is a variation in the amount of movement in the device configuration, and the stroke absorbing spring 33 between the slide member 32 and the link member 31 contracts and absorbs this overstroke. It is configured not to obstruct 34 movements. Even when the tooth surfaces of the clutch trigger gear 24 and the clutch gear 26 come into contact with each other during depression, the clutch trigger gear 24 cannot move, but the stroke absorbing spring 33 acts so as not to hinder the movement of the actuator. In addition, if the conveying roller is rotated in this state, the apex of the tooth surface slips and the proper position is reached. At this time, the slip occurs due to an appropriate elastic force, and the clutch is caused by the elastic force. A meshing force is generated.
[0044]
When the drive motor 14 is rotated forward or backward in this state, the rotation is transmitted from the clutch trigger gear 24 to the output gear 27 via the clutch gear 26, and the rotation of the feeding roller 2 is started. When the rotation is slightly started, the toothless portion of the output gear 27 is disengaged from the facing position of the clutch trigger gear 24, and is directly meshed to transmit the drive. Therefore, even if the carriage moves to the preliminary ejection position 13a and leaves the feeding trigger position 13b, the drive transmission to the feeding roller 2 continues. In this way, the feeding trigger is completed, and rotational driving for one rotation is transmitted to the feeding roller.
[0045]
The reason for this configuration is to perform the carriage operation necessary for improving the throughput in advance, but there is another reason described below. After the feeding roller 2 starts rotating, a load is generated except when the sheet placing table 1 in the initial stage of rotation is rising and before the later-described portion immediately before the end of one rotation. That is, loads are also generated between the tooth surfaces of the output gear 27 and the clutch trigger gear 24, and it becomes difficult for the clutch trigger gear 24 to be separated from the clutch gear 26 only by the urging force of the clutch separation spring 25 due to the friction. Then, although the carriage 9a is not present at the feed trigger position 13b, the drive transmission cannot be cut off and the second rotation is entered, resulting in a malfunction.
[0046]
In order to avoid this, it is important to release the carriage 9a before the above-described rise of the sheet placing table 1 where no load is generated occurs. Accordingly, it is desirable to provide a standby position detection sensor for the feed roller 2 so that the timing for releasing the carriage 9a is accurately determined. This is because it is not certain which teeth will engage the clutch, and since the clutch can only engage intermittently in the first place, it is difficult to measure accurately by step management and time management. Further, in order to determine whether or not to enter a special sequence when the position of the leading edge of the sheet P has become uncertain due to separation by the half-moon-shaped feeding roller 2, the feeding to the sheet leading edge sensor 5a is started. The number of steps until entering is counted and used. However, since the variation similarly occurs due to the error of the clutch portion, it is desirable to count the detection timing of the sheet leading edge sensor 5a from the standby position detection sensor of the feeding roller 2.
[0047]
Here, it goes without saying that the phase of the gear teeth formed on the outer periphery of the clutch trigger gear 24 and the clutch gear 26 and the phase of the clutch teeth are substantially matched. The clutch is designed so that there is a slight gap between them. On the contrary, the outer peripheral gear teeth are slightly shifted when driving is transmitted with the clutch teeth, but there is no problem as long as it is within the range of meshing when the teeth are engaged through the missing teeth. The purpose of this is to cut off the transmission path of the clutch trigger gear 24, the clutch gear 26, and the output gear 27 after the transmission of the output gear 27 and the clutch trigger gear 24 is ensured. This is also to prevent the clutch trigger gear 24 from being separated from the clutch gear 26, as described above.
[0048]
In this embodiment, it is described that the input of the driving force to the clutch unit is the clutch trigger gear 24 that slides. However, it is desirable to transmit the driving input to the clutch gear 26 that does not move originally. In this case, the drive transmission of the clutch trigger gear 24 can be cut only by shifting the phase of the clutch teeth with respect to the outer peripheral gear teeth, which is more effective.
[0049]
When the drive motor 14 is further rotated while the clutch trigger gear 24 and the output gear 27 are engaged, the output gear 27 and the feeding roller 2 eventually rotate once. Then, the toothless portion of the output gear 27 again faces the clutch trigger gear 24, the drive transmission is completed, and the rotation of the feeding roller 2 is also completed. Before the end of one rotation, the feeding roller 2 pushes down the sheet placing table 1 by a cam (not shown). At this time, it is designed to be pushed down once and come to a stable standby position so that the cam slides on the slope.
[0050]
This is in order to eliminate the drawbacks in the case of adopting a mechanism for stopping one rotation with a missing tooth as described above. The disadvantage is that if a missing tooth is plunged while a load is applied to the feeding roller 2, the missing tooth is returned due to the bending generated in the drive system and the like, and the gear just before entering the missing tooth and the clutch trigger gear 24 There is a risk that the teeth will be left forever and may make noise. However, if the cam shape is used, the feeding roller 2 is advanced by the slope of the cam regardless of the driving force of the driving system due to the upward biasing force of the sheet mounting table 1, so that the missing tooth portion also rotates and reliably rotates the teeth. You can prevent hits. The same effect can be obtained by providing a similar mechanism for the output gear 27 or other gears that transmit to the feeding roller 2.
[0051]
After the feed roller 2 makes one rotation, the conveying roller 6 is rotated forward or backward to determine the recording position, and then recording is started. As described above, since the conveyance accuracy of the conveyance roller 6 is important, this is to prevent the feeding roller 2 from being affected.
[0052]
FIG. 8 is a view when the carriage 9a moves from the feeding trigger position 13b to the front side of the apparatus (right side in the figure) and is positioned at the recovery and cap position 13c of the front side of the apparatus. Since the recovery unit and the cap are also operated by transmitting the drive of the drive motor 14, the cam 32b for the feed trigger needs not to be pushed even in this position.
[0053]
As shown in the drawing, when the actuator 34 further moves to the front side of the apparatus, the contact portion 35a of the latch member 35 gets over the cam 32b of the slide member 32 and reaches the front side of the apparatus. After the latch member 35 passes over the cam 32b, the clutch trigger gear 24, the link member 31, and the slide member 32 are restored to the standby position by the urging force of the clutch separating spring 25, and the feed trigger is not affected even if the drive motor 14 is driven. It does not take. When the latch member passes the cam 32b, the slide member 32 is pushed down as described above. However, if the drive motor 14 is not driven at this time, the feed trigger can be passed without being applied.
[0054]
As shown in FIG. 9, when the carriage 9a moves from the recovery and cap position 13c to the rear side of the apparatus, the actuator 34 tries to return to the standby position by the above-described urging means (not shown). At this time, the latch member 35 is in contact with the right side surface of the cam 32b of the slide member 32 at the left side surface of the abutting portion 35a and stays in that position against the urging force of the spring 37. It moves to the near side. The urging force of the spring 37 is set sufficiently weaker than the urging force of an actuator (not shown). During this time, the engaging portion 35c on the back surface of the latch member and the convex portions 34b, 34c of the actuator 34 do not interfere with each other because they move in the lateral direction.
[0055]
When the latch member 35 moves in this way, the engagement portion 35c is released from the restriction by the convex portions 34b, 34c, and the latch member 35 can be rotated in the direction of escaping from the cam 32b (counterclockwise direction in the figure). Only 37 is biased clockwise. When the actuator 34 further moves to the left, it moves by the length of the oblong hole 35b, and the latch member 35 rotates counterclockwise while resisting the urging force of the spring 37. Finally, as shown in FIG. Rotates to a height at which it can get over the slide member 32. When the actuator 34 further moves to the left, the latch member 35 gets over the slide member 32 completely. Thereafter, the latch member 35 moves to the left by the urging force of the spring 37, and returns to the position shown in FIG. 5 while rotating clockwise while the engaging portion 35c and the convex portions 34b, 34c of the actuator 34 come into contact. It becomes.
[0056]
If the structure using the latch member is not used, the actuator 34 must push down the slide member 32 only by the force of the urging means when the carriage escapes from the recovery and cap position 13c to the rear side of the apparatus. . However, according to the configuration of the present embodiment, the slide member 32 and the clutch portion do not operate while the actuator 34 returns. Therefore, regardless of the stroke absorbing spring 33 and the clutch separating spring 25 that are internal springs, it is only necessary to apply a biasing force that only wins against the weak spring 37 of the latch member 35 to the biasing means of the actuator 34. It should be noted that the spring 37 of the latch member 35 is only for returning the latch member, which is not loaded at the end of the ride over, to the standby state, and requires only a very weak biasing force. Therefore, the driving force required for the carriage 9a can also be suppressed.
[0057]
【The invention's effect】
As described above, in the image forming apparatus according to the present invention, when the drive motor rotates in the forward rotation direction, a spring clutch or a needle-type one-way clutch that switches quickly is used, and the drive motor rotates in the reverse direction. In some cases, by transmitting the drive using an inexpensive pendulum type one-way clutch, the number of gears used for drive transmission is different from one or an odd number between forward rotation and reverse rotation. It is possible to improve the certainty of holding onto the conveyance roller after correcting the skew of the sheet.
[Brief description of the drawings]
FIG. 1 is an overall configuration diagram of an image forming apparatus according to an embodiment.
FIG. 2 is a diagram illustrating a positional relationship in the depth direction of the apparatus.
FIG. 3 is a diagram for explaining the state of the drive switching means during normal rotation.
FIG. 4 is a diagram illustrating a state when a drive switching unit is reversely rotated.
FIG. 5 is a diagram for explaining the operation of the drive interrupting means during recording.
FIG. 6 is a diagram for explaining the operation of the drive interrupting means during the transition to the feeding trigger position.
FIG. 7 is a diagram for explaining the operation of the driving intermittent means at the feeding trigger position.
FIG. 8 is a diagram for explaining the operation of the drive intermittent means at the recovery position.
FIG. 9 is a diagram for explaining the operation of the drive interrupting means for leaving the recovery position.
FIG. 10 is a diagram for explaining the operation of the drive interrupting means for leaving the recovery position.
[Explanation of symbols]
P ... sheet
1 ... Sheet mounting table
1a: Sheet standard
2 ... Feed roller
3 ... Separation nail
4 ... Lower guide
5… Upper guide
5a ... Sheet tip sensor
6 ... Conveyance roller
6a Gear
6b: Conveying roller shaft
7 ... transport roller
8 Platen
9 Recording means
9a Carriage
9b ... Recording head
10… discharge roller
11… Spur
12… discharge tray
13a ... Pre-discharge position
13b ... Feed trigger position
13c Recovery and cap position
13d ... Recovery unit
14… Drive motor
15… Drive transmission mechanism
16, 17 ... Frame
18… Input gear
19… Output gear
20 ... deceleration sun gear
20a ... large diameter gear
20b ... Small diameter gear
21… Spring clutch input gear
22… Spring clutch output gear
23… Spring clutch
24… Clutch trigger gear
25… Clutch separation spring
26… Clutch gear
27… Output gear
28… Pendulum arm
29… Planetary gear
30… Side pressure spring
31… Link member
32 ... Slide member
32a ... Locking part
32b ... cam
33… Stroke absorbing spring
34… Actuator
34a ... Contact part
34b, 34c ... convex part
35… Latch member
35a ... Abutting part
35b ... oblong hole
35c ... engaging part
36… Shaft
37… Spring

Claims (3)

A feeding roller that separates and feeds the stacked sheets, a conveyance roller that conveys the sheet, a drive motor that is directly connected to the conveyance roller and that rotates forward and backward, and a drive motor that drives the feeding roller. In a sheet conveying apparatus having drive intermittent means for selectively transmitting and drive switching means for rotating the feeding roller in the conveying direction regardless of the rotation direction of the drive motor,
The drive switching means uses a spring clutch as a one-way clutch that transmits drive when the drive motor rotates the transport roller in the transport direction (hereinafter referred to as forward rotation), and rotates the transport roller in the direction opposite to the transport direction ( An image formation characterized in that a pendulum type is used for a one-way clutch that transmits drive during reverse rotation), and the number of gears used for forward and reverse drive transmission is varied from one to an odd number. apparatus. 2. The image forming apparatus according to claim 1, wherein a needle type one-way clutch is used instead of the spring clutch. The pendulum type one-way clutch is arranged so that two gears that should transmit drive are separated from each other, and a planetary gear that meshes with one gear as a sun gear can be rotated around the sun gear by an arm. The planetary gear is rotated according to the rotation direction of the sun gear and meshes with the other gear to which the drive is to be transmitted by applying a rotational load between the sun gear and the arm. The image forming apparatus according to claim 1, wherein the image forming apparatus is configured.

Images