JP2007022763A - Recording medium switch back device and image formation device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable normal/reverse rotation of a switch back roller 3 with a simple and inexpensive configuration and low electric power at a low noise level. <P>SOLUTION: A reduction gear train for supplying rotational drive force from a drive source 230 to the switch back roller 3 performing switch back conveyance by inverting a conveyance direction of recording media comprises a planetary gear mechanism 200. A drive connection means 221 enabling intermitting of a drive transmission action is provided between the planetary gear mechanism 200 and the drive source 230 to perform intermittent control. Thus, the switch back roller 3 can be controlled to be normally/reversely rotated without providing a conventional motor dedicated to normal/reverse rotation. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a recording medium switchback apparatus and an image forming apparatus that perform switchback conveyance by reversing the conveyance direction of a recording medium.

  For example, some image forming apparatuses such as copiers, printers, and facsimiles that enable double-sided image formation are equipped with a recording medium switchback device that reverses the front and back of the recording medium and performs switchback conveyance. If this recording medium switchback device is used, a pair of discharge rollers that normally discharge an image-formed recording medium to the outside of the apparatus is reversely rotated by designating a double-sided mode to form an image on both front and back sides of one recording medium. Can be performed automatically. As such a recording medium switchback device, a device described in Patent Document 1 below has been proposed.

  In the device described in Patent Document 1, forward and reverse rotation of the switchback roller constituted by the discharge roller pair is performed by forward and reverse rotation of the rotation direction of the motor that is a drive source. However, in this method of rotating the motor in the forward / reverse direction and rotating the switchback roller (discharge roller pair), a motor dedicated to forward / reverse rotation is added, so the motor drive noise increases. There is a problem that a large amount of electric power is required for rotational driving of the motor, and a large part cost is required for the motor itself.

Japanese Patent Laid-Open No. 08-188318

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a recording medium switchback device and an image forming apparatus that can perform forward and reverse rotation of a switchback roller with low noise and low power by a simple and low-cost configuration. And

  In order to achieve the above object, in the image forming apparatus according to the present invention, a switchback roller that reverses the recording medium conveyance direction to perform switchback conveyance, and a rotational driving force to the switchback roller via a gear train In the recording medium switchback device comprising the drive source for supplying the drive mechanism, the gear train includes a planetary gear mechanism, and the drive transmission function can be intermittently connected between the planetary gear mechanism and the drive source. Drive coupling means is arranged.

  According to the image forming apparatus of the present invention having such a configuration, any one of the sun gear, the planetary gear, and the internal gear that constitutes the planetary gear mechanism by controlling the drive coupling means to be disconnected or connected. It is possible to switch the rotation direction of the switchback roller connected to either the sun gear, the planetary gear or the internal gear constituting the planetary gear mechanism to forward or reverse by not transmitting the rotational driving force to it. It becomes. Therefore, according to the present invention, it is possible to control the switchback roller so that it can freely rotate in the forward and reverse directions without providing a motor for exclusive use in forward and reverse rotation as in the prior art.

  Thus, the present invention comprises a planetary gear mechanism that includes a reduction gear train that supplies a rotational driving force from a drive source to a switchback roller that reverses the conveyance direction of a recording medium and performs switchback conveyance. By connecting / disconnecting the planetary gear mechanism and the drive source to enable / disable the drive transmission action, the switchback roller can be rotated in the forward / reverse direction without using a dedicated motor for forward / reverse rotation. Since it can be freely controlled, the forward and reverse rotation of the switchback roller can be performed with a simple and low-cost configuration with low noise and low power, and the reliability of switchback conveyance for the recording medium. Can be greatly improved at low cost.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic structural diagram of a recording medium switchback device used in the image forming apparatus of the present invention.

  First, a first transport path 1 for transporting a recording medium after fixing from a fixing device (not shown) arranged on the lower side of the drawing is provided so as to extend upward. The first transport path 1 extends toward the discharge tray 2 so as to bend in a substantially horizontal direction, and the first transport path 1 is illustrated at an outlet portion that is open to the discharge tray 2. A switchback roller 3 that is rotationally driven by a signal from the controller that is omitted is disposed. Further, a recording medium detection sensor 4 for detecting an end of the recording medium is disposed on the front side (left side in the drawing) of the switchback roller 3 in the paper conveying direction, and is emitted from the recording medium detection sensor 4. An edge detection signal of the recording medium is input to the control device.

  Further, from the middle part of the first conveyance path 1 described above, more specifically, from the front side (left side in the figure) of the recording medium detection sensor 4 in the paper conveyance direction, the recording medium is switched when printing a double-sided image. A second transport path 5 for back transport extends so as to branch in a substantially Y shape, and a curved plate-like member is provided at a branch portion between the first transport path 1 and the second transport path 5. A flapper 6 is provided. The flapper 6 is disposed so as to be reciprocally rotatable in the x direction and the y direction between a normal conveyance position indicated by a broken line in the drawing and a reverse conveyance position indicated by a solid line, and is not illustrated. It is configured to be switched and driven in response to a signal from the control device.

  That is, during normal single-sided printing, the flapper 6 described above is rotated in the x direction and is held at the normal transport position indicated by the broken line in the drawing to close the entrance of the second transport path 5. The recording medium sent out from the fixing device (not shown) is conveyed to the switchback roller 3 along the first conveying path 1 as indicated by an arrow A in the drawing. Then, the driving roller 3a of the switchback roller 3 described above rotates in the direction of arrow B, and the recording medium is discharged in the direction of arrow C.

  In contrast, in duplex printing, the recording medium is first transported in the direction of arrow C by the switchback drive roller 3a that rotates in the direction of arrow B, but the recording medium detection sensor 4 detects the trailing edge of the recording medium. Immediately after the rotation, the flapper 6 rotates in the y direction and is held at the reverse conveyance position indicated by the solid line to block the first conveyance path 1. Next, the above-described switchback driving roller 3a is reversed in the direction of arrow D, and the recording medium is switched back in the direction of arrow E until the recording medium detection sensor 4 detects the trailing edge of the recording medium again. The recording medium is transported into 5 and the recording medium is reversed.

  Next, the rotational drive train of the switchback drive roller 3a described above is configured as follows. FIG. 2 is a schematic diagram showing a gear system for driving the switchback drive roller 3a, and FIG. 3 is a schematic diagram showing a planetary gear mechanism.

  As shown in FIGS. 2 and 3, the rotary shaft of the switchback drive roller 3 a described above is connected to the sun gear 200 a of the planetary gear mechanism 200. Three planetary gears 200b are arranged on the outer peripheral portion of the sun gear 200a so as to mesh with the sun gear 200a. In FIG. 2, only one planetary gear 200b is shown because of the illustrated relationship, and the other two are not illustrated.

  The planetary gear 200b of the planetary gear mechanism 200 is connected to the first drive train gear 211 that constitutes the first drive train via the carrier gear 210, and the first drive train gear 211. Is connected to a drive gear 230 of the image forming apparatus main body (not shown) via a first drive train idler gear 212.

  Further, on the outer periphery of the planetary gear 200b described above, an internal gear 200c arranged concentrically with the sun gear 200a is arranged to mesh with each planetary gear 200b. The internal gear 200c has a stepped gear configuration, and an internal gear stepped gear portion 200e provided along the outer periphery of the internal gear 200c is connected to the second drive train stepped gear 220 constituting the second drive train. The second drive train stage gear 220 is connected to a drive gear 230 that is rotated by a drive source of an image forming apparatus main body (not shown) via an electromagnetic clutch 221 as drive connection means. .

  The electromagnetic clutch 221 serving as the drive coupling means described above is configured to intermittently drive the drive transmission action related to the rotational drive force from the drive gear 230 by receiving a control signal (not shown). Further, the second drive train gear 220 described above is coupled to the torque limiter gear 222.

  In such a planetary gear mechanism 200, the gear ratio between the sun gear 202a and the planetary gear 200b described above is 1: 0.85, and the gear ratio between the sun gear 202a and the internal gear 202c is 1: 2. 7 has been made. That is, if the reduction ratio in the planetary gear mechanism 200 is calculated based on the reduction calculation of each known planetary gear train, when the axis of the sun gear 202a is set to the output, the input of the planetary gear 202b that is a known planetary type is input. Is 3.7, and the input of the known solar-type internal gear 202c is -2.7 (a negative sign indicates the opposite direction of rotation).

  Further, the reduction ratio between the drive gear 230 and the carrier gear 210 described above is set to 0.5, and the reduction ratio from the drive gear 230 to the internal gear 200c is set to 1.37. ing.

  Such a rotational drive train of the switchback drive roller 3a acts as shown in the table shown in FIG. 4, and the rotational direction of the switchback drive roller 3a is changed based on the intermittent transmission of the electromagnetic clutch 221 described above. It has been changed.

First, when the switchback drive roller 3a is rotated in the forward direction (in the direction of arrow B in FIG. 1) so as to discharge the recording medium in the direction of the discharge tray 2, as shown in FIG. The engagement of the electromagnetic clutch 221 is released, and the internal gear 200c is maintained in a stopped state by cutting off the drive transmission action through the second drive train. At this time, the rotational speed transmitted from the drive gear 230 to the planetary gear 200b via the first drive train, that is, the first drive train idler gear 212, the first drive train gear 211, and the carrier gear 210 is If the rotation speed of 230 is rotating at a constant speed of 120 rpm, from the relationship of the reduction ratio described above,
120 × 0.5 × 3.7 = 222 (rpm) (1)
Thus, the switchback drive roller 3a is rotationally driven in the forward direction (the direction of arrow B in FIG. 1) under the reduction ratio.

Next, when the switchback drive roller 3a reverses in the direction of arrow D in FIG. 1 and the recording medium is switched back and conveyed to the second conveyance path 5, as shown in FIG. The internal gear 200c is rotationally driven by engaging the clutch 221 and connecting the drive transmission action from the second drive train. At this time, the rotational speed transmitted from the drive gear 230 to the internal gear 200c through the second drive train is:
120 × 1.37 × (−2.7) = − 443.88 (rpm) (2)
It becomes.

Therefore, the number of rotations transmitted to the switchback drive roller 3a is (1) + (2)
222 + (− 443.88) = − 221.88 (rpm)
(The negative symbol is the reverse rotation direction arrow D direction), and the switchback drive roller 3a is rotationally driven in the reverse direction (the arrow D direction in FIG. 1) under the reduction ratio.

  A recording medium conveyance sequence by the switchback device at this time is shown in FIG. A line 500 indicating the recording medium detection of the recording medium detection sensor 4 is shown at the top of the figure, a line 501 indicating the on / off state of the electromagnetic clutch is shown at the second stage, and a flapper is shown at the third stage. 6 is a line 502 indicating the open / closed state, and a line 503 indicating the rotation direction of the switchback drive roller 3a is shown in the fourth row.

  First, the recording medium sent out from the fixing device of the image forming apparatus is conveyed toward the switchback roller 3 in the first conveying path 1 described above, and the recording medium detection sensor 4 detects the trailing edge of the recording medium. Then (see reference numeral 500a in FIG. 5), the flapper 6 rotates in the y direction in FIG. 1 to block the first transport path 1 (see reference numeral 502a in FIG. 5). Then, 20 msec later, the electromagnetic clutch 221 is turned on (see reference numeral 501a in FIG. 5), and the rotational driving force through the second drive train is supplied to the internal gear 200c of the planetary gear mechanism 200. As a result, as described above, the switchback drive roller 3a rotates in the direction D (reverse direction) shown in FIG. 1 (see reference numeral 503a in FIG. 5), and as a result, the recording medium moves to the second transport path 5. It is switched back toward you.

  When the recording medium thus switched back passes through the recording medium detection sensor 4 (see reference numeral 500b in FIG. 5), the flapper 6 moves in the x direction shown in FIG. While rotating in the opening direction (see reference numeral 502b in FIG. 5), the electromagnetic clutch 211 is turned off (see reference numeral 501b in FIG. 5), and at the same time, the switchback drive roller 3a is moved in the B direction in FIG. Direction) (see reference numeral 503b in FIG. 5).

  According to this embodiment having such a configuration, the electromagnetic clutch 221 serving as the drive coupling means is controlled to be disconnected so that the rotational driving force via the second gear train is not transmitted to the planetary gear mechanism 200. As a result, the rotational driving force of only the first gear train is transmitted to the planetary gear mechanism 200, and the rotational direction of the switchback driving roller 3a is set to the normal rotation direction. On the other hand, by controlling to connect the electromagnetic clutch 221 as the drive coupling means, the rotational driving force is also transmitted from the second gear train to the planetary gear mechanism 200, and the drive rotation from the second gear train is performed. However, the rotational direction of the switchback drive roller 3a is reversed using the planetary gear 200b as an idler gear. As is apparent from the operation of the planetary gear mechanism 200 described above, according to this embodiment, the switchback drive roller 3a can be controlled to freely rotate in the forward and reverse directions without providing a conventional forward / reverse rotation dedicated motor. Become.

  On the other hand, in another embodiment of the present invention shown in FIG. 6, the rotary shaft of the switchback drive roller 3 a is connected to the sun gear 600 a provided in the planetary gear mechanism 600 and the sun gear is provided. Three planetary gears 600b (only one is shown in FIG. 6) are arranged on the outer periphery of 600a so as to mesh with the sun gear 600a. Each of these planetary gears 600b is connected to the first drive train stage gear 611 of the first drive train via the carrier gear 610, and drives the image forming apparatus main body (not shown) via the first drive train idler gear 612. It is connected to a drive gear 630 that is rotated by a source.

  Here, the first drive train gear 611 described above is provided with drive coupling means having a gear locking mechanism using a solenoid as shown in FIG. In this drive connecting means, the first drive train stage gear 611 is constituted by a chipped gear having a chipped portion 611a that does not form a gear on a part of the circumferential gear. Further, the step gear 611 of the first drive train is provided with an electromagnetic solenoid 650 attached to a part of a drive box (not shown), and the claw portion 650a is turned on and off by the electromagnetic solenoid 650 being turned on and off. The rotation is controlled in the direction. The claw portion 650a of the electromagnetic solenoid 650 is engaged with a locking portion 611b formed in a step shape on the inner peripheral portion of the first drive row gear 611 so as to be locked in the rotational direction. It is made to the structure to do.

  Further, a rotational moment is applied to the first drive train stage gear 611 in the S direction in the figure by a tension spring (not shown). Normally, the first drive train stage gear 611 is locked to the claw portion 650a of the electromagnetic solenoid 650 described above. It is prevented from rotating. When the electromagnetic solenoid 650 is turned on and the claw portion 650a is attracted, the first drive row gear 611 is rotated by the urging force of the tension spring. Further, the missing tooth portion 611a is disposed so as to face the first drive train idler gear 612 that is rotationally driven by the drive gear 630 at the stop position of the first drive train gear 611 described above, and the electromagnetic solenoid 650 described above. Unless the claw portion 650a is sucked by turning on, the rotational drive from the drive gear 630 is not transmitted.

  Returning to FIG. 6 again, an inner gear 600c is arranged to mesh with the outer periphery of the planetary gear 600b in the planetary gear mechanism 600 described above. The internal gear 600c has a stepped gear configuration, and a stepped gear portion 600e provided along the outer periphery of the internal gear 600c is driven via the second drive train stage gear 620 and the second drive train idler gear 621. It is connected to the gear 630.

  At this time, the drive gear 630 is configured to include a one-way clutch mechanism (not shown), and a load is applied when the user forcibly rotates it in the forward direction by jamming or the like. The second drive train rotates without any gear breakage being avoided.

  Here, the gear ratio between the sun gear 602a and the planetary gear 600b of the planetary gear mechanism 600 is 1: 0.85, and the gear ratio between the sun gear 602a and the internal gear 602c is 1: 2.7. It has become. If the reduction ratio in the planetary gear mechanism 600 in which the output is set to the sun gear 602a axis is calculated based on the reduction calculation of each known planetary gear train, the planetary gear 602b input that is a known planetary gear has a value of −3.7 ( The negative sign indicates the opposite direction of rotation), and becomes 2.7 when the internal gear 602c, which is a known solar type, is input. At this time, the reduction ratio between the drive gear 630 and the carrier gear 610 is set to 1.02, and the reduction ratio from the drive gear 630 to the internal gear 600c is set to 0.7. Yes.

The table shown in FIG. 8 shows the difference in the rotation of the switchback drive roller 3a due to the drive contact / separation of the electromagnetic solenoid 650. First, the switchback drive roller 3a rotates in the normal direction to discharge the recording medium to the discharge tray 2. When rotating so as to discharge in the direction (in the direction of arrow B in FIG. 1), as shown in FIG. 8 (a), the electromagnetic solenoid 650 is locked and the carrier gear 610 is stopped. It becomes a state. At this time, if the rotational speed transmitted from the drive gear 630 to the internal gear 600c by the second drive train is the rotational speed 630 of the drive gear rotating at a constant speed of 120 rpm,
120 × 0.7 × 2.7 = 226.8 (rpm) (1)
Thus, the switchback driving roller 3a rotates in the forward direction.

Next, when the switchback driving roller 3a is reversed and the recording medium is switched back to the second transport path 5 (in the direction of arrow D in FIG. 1), as shown in FIG. The locking of the electromagnetic solenoid 650 is released and the carrier gear 610 is rotated. At this time, the number of revolutions transmitted from the drive gear 630 to the internal gear is
120 × 0.5 × (−3.7) = − 452.88 (rpm) (2)
It becomes.

And the rotation speed transmitted to the switchback drive roller 3a is from (1) + (2),
226.8 + (− 452.88) = − 226.08 (rpm)
(The negative symbol is the forward rotation direction (arrow B direction)), and the switchback drive roller 3a is reversely rotated.

  According to this embodiment having such a configuration, the electromagnetic solenoid 650 as the drive connecting means is controlled to be disconnected so that the driving force via the first gear train is not transmitted to the planetary gear mechanism 600. Thus, the rotational driving force of only the second gear train is transmitted to the planetary gear mechanism 600, and the rotational direction of the switchback driving roller 3a is set to the normal rotation direction. On the other hand, by controlling so that the electromagnetic solenoid 650 as the drive connecting means is connected, the rotational driving force is transmitted to the planetary gear mechanism 600 also from the first gear train on the other side. The rotation direction of the switchback driving roller 3a is reversed using the planetary gear 600b of the planetary gear mechanism 600 as an idler gear. As is apparent from the above-described operation, in this embodiment, the switchback drive roller 3a can be controlled to freely rotate forward and backward without providing a conventional forward / reverse rotation dedicated motor.

  As mentioned above, although the embodiment of the invention made by the present inventor has been specifically described, the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention. Not too long.

  For example, in each of the above-described embodiments, an electromagnetic clutch or an electromagnetic solenoid is used as the drive coupling means, but various other types of drive coupling means can be employed.

  The recording medium switchback device 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.

FIG. 2 is an enlarged side view illustrating a part of an image forming apparatus to which the recording medium switchback device according to the present invention is applied. It is a systematic diagram showing the gear train for switchback roller driving concerning one embodiment of the present invention. It is the schematic diagram which showed the planetary gear mechanism concerning one Embodiment of this invention. It is the table | surface which showed the difference in rotation of the switchback roller based on the drive contact / separation of the electromagnetic clutch concerning one Embodiment of this invention. It is a timing chart showing a recording medium conveyance sequence of the switchback device according to the embodiment of the present invention. It is a systematic diagram showing the gear train for switchback roller drive in other embodiments of the present invention. It is side surface explanatory drawing which showed the solenoid which is the drive connection means in other embodiment of this invention, and gear arrangement. It is the table | surface which showed the difference in rotation of the switchback drive roller 3a by the drive contact / separation of the electromagnetic solenoid in other embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st conveyance path 2 Discharge tray 3 Switchback roller 3a Switchback drive roller 4 Recording medium detection sensor 5 2nd conveyance path 6 Flapper 200,600 Planetary gear mechanism 200a, 600a Sun gear 200b, 600b Planetary gear 200c, 600c Internal gear 221 Electromagnetic clutch (drive coupling means)
230 drive gear 611a chipped portion (drive connection means)
650 Electromagnetic solenoid (drive coupling means)
650a Claw portion (drive connecting means)

Claims (10)

A recording medium switchback device comprising: a switchback roller that reverses the recording medium conveyance direction to perform switchback conveyance; and a drive source that supplies a rotational driving force to the switchback roller via a gear train. In
The gear train includes a planetary gear mechanism,
A recording medium switchback device, characterized in that drive coupling means is provided between the planetary gear mechanism and the drive source so that the drive transmission action can be interrupted. The planetary gear mechanism includes a sun gear that transmits a rotational driving force to the switchback roller directly or via an appropriate gear train, and at least one planetary gear that revolves while rotating on the outer periphery of the sun gear. And an internal gear arranged concentrically with the sun gear so as to mesh with the planetary gear from the outer peripheral side,
The planetary gear and the internal gear are connected to the drive source via a first gear train and a second gear train, respectively.
2. The recording medium switchback device according to claim 1, wherein the drive connecting means is provided on at least one side of the first gear train and the second gear train. The planetary gear mechanism includes an internal gear that transmits a rotational driving force to the switchback roller directly or through an appropriate gear train, and at least one planet that revolves while rotating on the inner periphery of the internal gear. A gear, and a sun gear arranged concentrically with the internal gear so as to mesh with the planetary gear from the inner peripheral side,
The planetary gear and the sun gear are coupled to the drive source via a first gear train and a second gear train, respectively.
2. The recording medium switchback device according to claim 1, wherein the drive connecting means is provided on at least one side of the first gear train and the second gear train. X is the gear ratio of the gear train when the switchback roller is connected to rotate in the forward direction with respect to the sun gear, and the gear ratio of the gear train is connected so that the switchback roller rotates in the reverse direction. Y, where N is the rotational speed of the drive source,
X ・ N ≠ Y ・ N
The recording medium switchback device according to claim 2, wherein the recording medium switchback device has the following relationship.   The drive connecting means is configured to be controlled based on information obtained through a recording medium edge detecting means provided on the upstream side in the recording medium conveyance direction with respect to the switchback roller. The recording medium switchback device according to any one of claims 1 to 3.   4. The recording medium switchback device according to claim 1, wherein the drive transmission means includes an electromagnetic clutch. The drive transmission means includes an electromagnetic solenoid, a chipped gear disposed in the reduction gear train, and a locking portion whose rotation is locked by the operation of the electromagnetic solenoid,
4. The recording medium switchback device according to claim 1, wherein transmission of a rotational driving force is controlled by an operation of the electromagnetic solenoid.   4. The switchback roller includes a pair of rollers having a function of discharging an image-formed recording medium that has completed predetermined image formation to the outside of the apparatus. Recording medium switchback device.   The one-way transmission member which transmits rotational driving force only to one direction is arrange | positioned between the drive trains from the said drive source to said 1st drive train and said 2nd drive train. The recording medium switchback device according to claim 3. 10. An image forming apparatus, wherein the recording medium switchback device according to claim 1 is provided in a recording medium discharge portion.

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