JP2006125576A - Tooth-chipped gear driving mechanism and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize both high durability and reduction of size by simple constitution. <P>SOLUTION: The rotational energizing force of an energizing means 25 for energizing a tooth-chipped gear 21 of a one-revolution drive holding mechanism toward the paper feeding rotating direction is applied to the tooth-chipped gear 21 only during the initial rotation section, immediately after it, the final rotation section and immediately before it, and it is not applied during the remaining rotation section of the driving rotation section, whereby the rotational energizing force of the energizing means 25 is loaded on the tooth-chipped gear only in the required timing and not applied during the unnecessary driving rotation section, so that the load stress to the tooth-chipped gear 21 is held down to the minimum and the space for disposing the energizing means is reduced. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an intermittent gear drive mechanism and an image forming apparatus that are configured to rotationally drive a partially-toothed gear having a non-gear portion in a part of a gear portion by a drive gear and to be held at a standby position by a gear lock unit. About.

  In general, in various image forming apparatuses such as an electrophotographic copying machine and a printer, a sheet-like recording material such as a recording sheet is fed into a sheet feeding path by one rotation of a sheet feeding roller formed to have a substantially D-shaped cross section, for example. Some are configured to be sent out. The sheet feed roller configured to feed out one sheet-like recording material for each rotation is usually provided with a one-rotation drive holding mechanism for holding the sheet feed roller in a standby position for each rotation. ing. As the one-rotation drive holding mechanism at that time, a missing gear drive mechanism as described in Patent Documents 1 to 3 below is usually employed. The missing gear drive mechanism has a non-gear portion formed so as to cut out a part of a gear portion provided along the outer peripheral edge of the missing gear over an appropriate central angle range. When the drive gear meshes with the gear portion of the toothed gear and the toothless gear rotates, while the drive gear does not mesh with the non-gear portion of the toothless gear, the toothless gear is attached. By being engaged with the gear lock means while obtaining the rotation biasing force from the biasing means, it is held at the standby position.

  The conventional one-rotation drive holding mechanism will be described in detail. For example, in the one-rotation drive holding mechanism shown in FIG. 4, the missing gear 1 is attached to the drive shaft of the paper feed roller (not shown). In addition, the toothless gear 1 is provided with a gear portion 1a along the outer peripheral edge, and a non-gear portion formed so as to cut out a part of the gear portion 1a over an appropriate central angle range. 1b is provided. First, before the start of paper feeding, the above-mentioned missing gear 1 is held at the standby position by the gear locking means 2 as shown in FIG. At this time, the upper end portion of the tension spring 3 as an urging means is attached to the rotating action receiving pin 1c provided in the toothless gear 1, and the tension spring 3 is pulled downward in the figure. A clockwise urging force is applied to the partial gear 1 by the force.

  Next, when the paper feed start timing is reached, the gear locking means 2 is released from the partial gear 1 as shown in FIG. 4B, and the partial gear 1 is moved to the standby position by the rotational biasing force of the tension spring 3 described above. The gear portion 1a of the partial gear 1 is meshed with the drive gear 4 by the initial rotation in the clockwise direction in FIG. In this manner, the rotation section from the standby position 1 to immediately before meshing with the drive gear 4 is referred to as an “initial rotation section”.

  Further, when the gear portion 1a of the missing gear 1 meshes with the drive gear 4 as described above, the missing gear is caused by the rotational driving force transmitted from the drive gear 4 as shown in FIGS. 4c and 4d. 1 rotates together with a sheet feeding roller (not shown) in the sheet feeding direction, and a sheet feeding operation is performed on one sheet-like recording material by one rotation. After the sheet-like recording material is fed, the non-gear portion 1b of the toothless gear 1 faces the drive gear 1 so that the gears 4 and 1 are not engaged with each other. In this way, a rotation section from when the toothless gear 1 meshes with the drive gear 4 to just before the non-engagement state is defined as a “drive rotation section”.

  On the other hand, when the toothless gear 1 is brought into the non-engagement state with the drive gear 4 as described above, the tension spring 3 as the urging means is slightly contracted beyond the fully extended upper fulcrum position. From the tension spring 3, a clockwise urging force in the clockwise direction is applied to the toothless gear 1. And the said partial gear 1 will be returned to the stand-by position shown by FIG. The above-mentioned gear locking means 2 is engaged with the partial gear 1 returned to the standby position, whereby the partial gear 1 is held at the standby position. Thus, the rotation section from when the toothless gear 1 is brought into the non-engagement state with the drive gear 4 until it is returned to the standby position is defined as a “final rotation section”.

JP-A-6-56283 Japanese Patent Laid-Open No. 11-011709 JP 2004-010192 A

  However, in such a conventionally proposed sheet-shaped recording material feeding device, the tension force from the tension spring 3 as the biasing means is always applied to the missing gear 1 and its rotating shaft. It has become. Moreover, since the tension spring 3 is attached to the rotating action receiving pin 1c arranged at an eccentric position of the toothless gear 1, the tension force varies so as to repeat between the maximum value and the minimum value. . For this reason, the rotating action receiving pin 1c described above and the hook portion of the tension spring 3 are constantly subjected to repeated stress, and the corresponding parts are damaged by the constantly acting repeated stress. Is prone to occur.

  Further, since the tension spring 3 repeats a large eccentric movement to the left and right in the figure during the rotation of the toothless gear 1 described above, a relatively large arrangement space is required, which is an obstacle to downsizing the entire apparatus. There is also a risk of becoming.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a sheet-like recording material sheet feeding apparatus that has high durability and can be miniaturized with a simple configuration.

  In order to achieve the above object, a missing tooth having a non-gear portion provided so as to cut out a part of a gear portion provided along the outer peripheral edge according to claim 1 of the present invention over an appropriate central angle range. A gear, a drive gear that meshes with the gear portion of the toothless gear and rotationally drives the toothless gear, an urging means that urges the toothless gear in the rotational drive direction, and an engagement with the toothless gear. And a gear locking means for holding the missing tooth gear in the standby position.The biasing means biases the missing tooth gear when the missing gear is in the standby position. While being held by the gear lock means, the partial gear is configured not to be biased when the partial gear is meshed with the drive gear.

  According to the partial gear drive mechanism according to claim 1 having such a configuration, a load is applied to the partial gear only at a timing when the rotational biasing force by the biasing means is required, and the rotational biasing by the biasing means is performed. Since the load does not act on the missing gear in the drive rotation section where no force is required, the load stress on the missing gear is minimized, and the arrangement space for the biasing means is reduced accordingly. It has become.

According to a second aspect of the present invention, the biasing gear driving mechanism according to the first aspect comprises a torsion coil spring, and the rotation action portion extending from one end side of the torsion coil spring is provided at the standby position with the second tooth gear. It is made the structure which urges | biases the action receiving part of the said part-tooth gear so that may be pressed to a rotation direction.
According to the partial gear drive mechanism according to claim 2 having such a configuration, the biasing means is easily formed by the torsion coil spring.

Furthermore, in the toothless gear drive mechanism according to claim 3, the rotationally acting portion of the torsion coil spring according to claim 2 includes a guide portion that abuts against the acting receiving portion of the toothless gear in the drive rotation section of the toothless gear. And the guide portion is formed such that when the standby position is entered from the drive rotation section, the action receiving portion of the partial gear disengages from the guide portion and shifts to the spring action portion side. Has been.
According to the missing gear drive mechanism according to claim 3 having such a configuration, the missing gear is smoothly and reliably returned to the standby position by the guide action of the guide portion of the torsion coil spring.

Furthermore, in the partial gear drive mechanism according to claim 4, the urging means in claim 1 comprises a leaf spring, and the rotation action portion provided on one end side of the leaf spring is in the standby position, It is made the structure which urges | biases the action receiving part of the said missing tooth gear so that a missing tooth gear may be pressed in a rotation direction.
According to the partial gear drive mechanism according to the fourth aspect having such a configuration, the urging means is easily formed by the leaf spring.

According to a fifth aspect of the present invention, the guide gear that contacts the action receiving portion of the partial gear in the drive rotation section of the partial gear is provided on the other end side of the leaf spring in the fourth aspect. The guide portion is formed such that when the standby position is entered from the drive rotation section, the action receiving portion of the partial gear is detached from the guide portion and moves to the rotation action portion side. Has been.
According to the missing gear drive mechanism according to claim 5 having such a configuration, the missing gear is smoothly and reliably returned to the standby position by the guide action of the guide portion of the leaf spring, particularly in the case of a leaf spring. Since the guide portion is formed continuously with the rotation action portion, the overall configuration is further facilitated.

  On the other hand, in an image forming apparatus according to a sixth aspect of the invention, the sheet-shaped recording medium paper feeding device includes the missing gear drive mechanism according to any one of the first to fifth aspects, and the sheet-like recording medium paper feeding device. The above-described actions can be effectively obtained.

  As described above, the missing gear drive mechanism according to claim 1 of the present invention is provided with the biasing means for biasing the missing gear in the rotational drive direction, and when the missing gear is in the standby position, the missing gear is attached. While being held by the gear lock means, the configuration is such that when the missing gear is engaged with the drive gear, the missing gear is not biased, thereby minimizing the load stress on the missing gear. Since the arrangement space of the urging means is made small, it is possible to realize both high durability and downsizing with a simple configuration, and improve the reliability of the apparatus while improving its usefulness. Can also be increased.

  According to a second aspect of the present invention, the toothless gear driving mechanism is connected to the rotationally acting portion of the torsion coil spring according to the second aspect of the present invention with a guide portion that abuts against the acting receiving portion of the toothless gear in the drive rotational section of the toothless gear. The guide part of the torsion coil spring is formed so that the action receiving part of the toothless gear is detached from the guide part and moves to the spring action part side when entering the standby position from the drive rotation section. The above-described effects can be obtained more reliably because the missing gear is smoothly and reliably returned to the standby position by the guiding action.

Furthermore, the sheet-like recording material sheet feeding device according to claim 4 is configured such that the urging unit according to claim 1 is formed from a leaf spring, and the rotation action portion provided on one end side of the leaf spring includes a standby position. In addition to the above-described effects, the operation receiving portion of the partial gear is configured to be urged so as to press the partial gear in the rotational direction in FIG. Thus, the device can be further simplified.

  Further, the sheet-like recording material feeding device according to claim 5 is provided with a guide portion that contacts the action receiving portion of the toothless gear in the drive rotation section of the toothless gear on the other end side of the leaf spring in claim 4. The guide portion is formed so that the action receiving portion of the toothless gear is detached from the guide portion and moves to the rotation action portion side when entering the standby position from the drive rotation section. Since the guide gear of the leaf spring guides the missing gear smoothly and reliably to the standby position, the guide portion and the rotation action portion can be continuously formed. The obtained effect can be obtained more reliably and productivity can be improved.

  On the other hand, an image forming apparatus according to a sixth aspect includes the missing gear driving mechanism according to any one of the first to fifth aspects in a sheet-like recording medium sheet feeding device, and the above-described sheet-like recording medium sheet feeding device has the above-described configuration. Therefore, the above-described effects can be satisfactorily obtained in various image forming apparatuses.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Prior to that, the overall structure of the image forming apparatus will be outlined with a laser printer as an example.
In the laser printer 10 shown in FIG. 2, image information sent from an external computer is converted into light modulation information 11a by the laser emission writing unit 11 via a video controller (not shown) in the process cartridge 12. An image is formed in a spot shape on a photosensitive drum 121 as an image carrier provided on the photosensitive drum 121, and the light spot is reciprocated in the axial direction (main scanning direction) of the photosensitive drum 121, whereby the photosensitive drum 121 is scanned. Then, an electrostatic latent image corresponding to the formed image is formed. Then, an unfixed toner image is formed by supplying developer (toner) to the electrostatic latent image on the photosensitive drum 121 from a developing device 122 that is also integrally provided in the process cartridge 12. It has become so.

  On the other hand, on the lower side of the apparatus, recording sheets P as sheet-like recording materials stored in a sheet feeding unit such as the sheet feeding cassette 13 are stored in a stacked manner, and the recording sheets P in the sheet feeding cassette 13 are stored. Then, the sheet is pulled out by the sheet feeding roller 13a and sent to the transfer area facing the above-described photosensitive drum 121 while being properly timed by the registration roller 14. The structure of the paper feed roller 13a will be described later.

  Further, a transfer roller 15 as a contact transfer member is in contact with and disposed in the transfer area of the photosensitive drum 121 so as to contact the surface of the photosensitive drum 121. A transfer bias is applied to the transfer roller 15, and the unfixed toner image on the photosensitive drum 121 is electrostatically transferred onto the recording paper P by the transfer bias. Further, the toner remaining on the photosensitive drum 121 after the transfer is scraped off by the sliding contact force of the cleaning roller 123 disposed so as to come into pressure contact with the surface of the photosensitive drum 121.

  Furthermore, the recording paper P carrying the unfixed toner by the transfer action described above is conveyed toward the fixing device 16 disposed adjacent to the process cartridge 12. The fixing device 16 is provided with a fixing roller 16a and a pressure roller 16b as heaters, and unfixed toner on the recording paper P is removed by the heat fixing operation of the fixing roller 16a and the pressure roller 16b. As a result of heating and melting, the toner image is fixed and fixed on the recording paper P. The recording paper P on which the toner image is fixed by such a heat fixing operation is discharged onto the paper discharge tray 17.

  Here, the sheet feeding roller 13a disposed at the outlet of the sheet feeding cassette 13 is formed of a long member having a substantially D-shaped cross section, and the sheet feeding roller 13a is rotated by one rotation. The configuration is such that a sheet of recording paper P is sent out into the paper feed path. The sheet feed roller 13a configured to feed out one sheet of recording paper P for each rotation as described above has a one-rotation drive holding mechanism for holding the sheet feed roller 13a in the standby position for each rotation. An incisor gear drive mechanism is attached.

  The incisor gear drive mechanism employed in the present embodiment has a structure as shown in FIG. 1, and has a missing tooth attached to the paper feed drive shaft 13b of the paper feed roller 13a (see FIG. 2). The gear 21 is configured to rotate integrally with the paper feed roller 13a in the paper feed rotation direction indicated by the arrow in the drawing. The toothless gear 21 is provided with a gear portion 21a made of normal transmission teeth along the outer peripheral edge of the toothless gear 21, and a part of the gear portion 21a is notched so as to be not geared. A portion 21b is provided. The non-gear portion 21b is provided over an appropriate central angle range corresponding to a rotation operation described later.

  The gear portion 21a of the toothless gear 21 is disposed so as to be able to mesh with a drive gear 23 fixed to the rotary drive shaft 22, as shown in FIGS. 1b and 1c. When the meshing state is established, the rotational driving force from the drive gear 23 is transmitted to the gear portion 21 a of the toothless gear 21. On the other hand, as shown in FIG. 1a, when the non-gear portion 21b of the above-mentioned missing gear 21 faces the driving gear 23, the missing gear 21 is in a non-meshing state with respect to the driving gear 23. The rotational driving force from the drive gear 23 is not transmitted to the toothless gear 21 side.

  Further, an annular body 21c is formed on the outer peripheral portion of the toothless gear 21 so as to be concentric with the paper feed drive shaft 13b, and at one place in the circumferential direction of the annular body 21c. An engagement step portion 21d made of a step portion in the radial direction is provided. The engaging step portion 21d has a step surface facing the paper feeding rotation direction (right rotation direction in the drawing) of the above-described missing gear 21, and a gear lock is provided with respect to the step surface of the engaging step portion 21d. A front end locking portion 24 a 1 of a flapper 24 a provided in a lock solenoid 24 as a means is provided so as to be able to engage or release in the rotation direction of the toothless gear 21. When the flapper 24a of the lock solenoid 24 is engaged with the toothless gear 21 side, the rotation of the toothless gear 21 is thereby restricted, and the sheet feeding roller 13a in a non-operating state is held at the standby position. It is like that.

  The flapper 24a of the lock solenoid 24 has an elongated plate-like main body 24a2. The base side (lower side in the figure) of the main body 24a2 of the flapper 24a is attached in a swingable state with respect to the fixed frame 24b, and the swinging end (upper end in the figure) of the main body 24a2. The tip locking portion 24a1 described above is provided so as to be bent in a substantially square shape. Then, as shown in FIG. 1a, the base portion side end portion (the lower end portion in the drawing) of the main body portion 24a2 is pulled and urged by a coil spring 24c extending from the fixed frame 24b side. A front end locking portion 24a1 provided on the swing side of 24a is pressed toward the missing gear 21 side.

  Furthermore, a main body portion of the lock solenoid 24 is mounted in the above-described fixed frame 24b, and an electromagnetic action portion 24d provided on the distal end side (the right end side in the drawing) of the lock solenoid 24 is shown in FIG. 1b and FIG. As shown in FIG. 1c, by sucking the main body 24a2 of the flapper 24a described above, the locking portion 24a1 is released from the engagement step portion 21d of the toothless gear 21 to be released. It has become.

  On the other hand, the above-described missing gear 21 is provided with a torsion coil spring 25 as an urging means that urges the missing gear 21 to rotate in the paper feeding rotation direction (clockwise direction in the drawing). From one end side of the torsion coil spring 25 in the axial direction (perpendicular to the paper surface in FIG. 1), a rotation action portion 25a is provided so as to extend in the coil tangential direction. As shown in FIG. 1a and FIG. 1c, a rotational action receiving pin 26 erected on the above-mentioned toothless gear 21 is provided in the middle of the rotational action part 25a provided on the torsion coil spring 25. When the rotational action portion 25 a on the side of the torsion coil spring 25 is pressed against the rotational action receiving pin 26 of the toothless gear 21, the rotational action receiving pin is applied by the torsion elastic force of the torsion coil spring 25. 26 is pressed to apply a rotational biasing force in the paper feeding rotation direction (clockwise direction in the drawing) to the missing gear 21.

  At this time, the rotation action portion 25a of the torsion coil spring 25 described above is set so as to be in contact with the rotation action receiving pin 26 of the toothless gear 21 only in the following specific rotation section. Then, only in the specific rotation section, the rotational biasing force from the torsion coil spring 25 side is applied to the toothless gear 21 side. In other rotation sections other than the specific rotation section, The rotation action portion 25a of the coil spring 25 is separated without being pressed against the rotation action receiving pin 26 of the toothless gear 21 so as not to apply a rotation biasing force to the toothless gear 21.

  Hereinafter, the definition of each rotation section in the toothless gear 21 and the configuration relating to the application of the rotational biasing force of the torsion coil spring 25 in each rotation section will be described in detail.

  First, in the stage before the start of paper feeding, the toothless gear 21 is held at the “standby position” by the locking action of the lock solenoid 24 as shown in FIG. At this “standby position”, a rotational action portion 25a of a torsion coil spring 25 as an urging means is pressed against the rotational action receiving pin 26 provided on the toothless gear 21 from the upper side in the drawing, A rotational urging force in the paper feeding rotation direction (clockwise direction in the drawing) is applied from the rotation action portion 25a of the coil spring 25 to the toothless gear 21 side.

  Next, when the sheet feeding start timing is reached, the lock solenoid 24 is released from the missing gear 21 as shown in FIG. 1B, and the missing gear 21 is moved to the “standby position” by the rotational biasing force of the torsion coil spring 25 described above. The gear portion 21 a of the toothless gear 21 is meshed with the drive gear 23. In this way, the rotation section from the “standby position” to the position immediately before meshing with the drive gear 23 is referred to as the “initial rotation section”. In the “initial rotation section”, as described above, a rotational biasing force in the sheet feeding rotation direction (clockwise direction in the drawing) is applied from the torsion coil spring 25 to the toothless gear 21.

  Further, as shown in FIGS. 1b and 1c, when the gear portion 21a of the toothless gear 21 meshes with the drive gear 23, the toothless gear 21 is fed by the rotational driving force transmitted from the drive gear 23. It rotates in the paper feeding direction together with the roller 13a (see FIG. 2), and the paper feeding operation is performed on one sheet of recording paper P by one rotation. Then, after the sheet-like recording paper P is fed, the non-gear portion 21b of the toothless gear 21 described above faces the drive gear 23, so that the two gears 21, 23 are not in contact with each other. It becomes a state of meshing. Thus, the rotation section from when the toothless gear 21 meshes with the drive gear 23 to just before the non-engagement state is defined as a “drive rotation section”.

  Immediately after the start of the “drive rotation section” described above (FIG. 1 b), the rotation action portion 25 a of the torsion coil spring 25 is pressed against the rotation action receiving pin 26 of the toothless gear 21 from the upper side in the figure, and the torsion coil spring 25. Rotation biasing force in the sheet feeding rotation direction (clockwise direction in the drawing) is applied from the rotation action portion 25a to the toothless gear 21 side. On the other hand, in the remaining rotation section (rotation section between FIG. 1 b and FIG. 1 c) of the “drive rotation section”, the rotation action portion 25 a of the torsion coil spring 25 described above is engaged in the locking action of the stopper 27, which will be described later. Thus, the rotational action portion 25a of the torsion coil spring 25 rotates away from the rotational action receiving pin 26 of the toothless gear 21. That is, the toothless gear 21 at this time is exclusively rotationally driven in the paper feeding rotation direction (clockwise direction in the drawing) by the rotational driving force applied from the drive gear 23.

  On the other hand, the rotation action portion 25a of the torsion coil spring 25 as the urging means immediately before the toothless gear 21 is brought into the non-engagement state with the drive gear 23 as described above, the rotation action receiving pin 26 of the toothless gear 21. Is pressed again from the upper side in the figure, and a rotational urging force in the sheet feeding rotation direction (clockwise direction in the figure) is applied from the rotation action portion 25a of the torsion coil spring 25 to the missing gear 21 side. .

  Then, due to the rotational urging force of the torsion coil spring 25 at that time, the missing gear 21 is returned to the “standby position” shown in FIG. The above-described lock solenoid 24 is engaged with the missing tooth gear 21 returned to the “standby position”, whereby the missing tooth gear 21 is held at the “standby position”. Thus, the rotation section from when the toothless gear 21 is brought into the non-engagement state with the drive gear 23 until it is returned to the “standby position” is defined as a “final rotation section”. In the “final rotation section”, as described above, a rotational biasing force in the sheet feeding rotation direction (clockwise direction in the drawing) is applied from the torsion coil spring 25 to the missing gear 21 side.

  As described above, the torsion coil spring 25 as the biasing means is provided with the rotational action receiving pin of the toothless gear 21 in the “initial rotation section” and immediately after it, and in the “final rotation section” and immediately before it. In the remaining rotation section of the “drive rotation section”, the torsion coil spring 25 is separated from the toothless gear 21 side in the remaining rotation section of the “drive rotation section”. The rotational urging force from 25 does not act on the missing gear 21.

  On the other hand, a guide portion 25b is continuously connected to the rotational action portion 25a of the torsion coil spring 25 described above so as to be bent in a generally U shape toward the upper side in the figure. The guide portion 25b is configured to come into contact with the rotational action receiving pin 26 of the toothless gear 21 from the “drive rotation section” immediately before entering the “final rotation section” described above. Immediately before entering the “final rotation section”, the rotation receiving pin 26 of the toothless gear 21 is separated from the guide portion 25b and moves to the rotation operation portion 25a side. By such a guide action of the guide portion 25b, in the “final rotation section” described above, a rotational biasing force in the sheet feeding rotation direction (clockwise direction in the drawing) is reliably applied from the torsion coil spring 25 to the missing gear 21. It is like that.

  Further, an engaging portion 25c is continuously provided from the guide portion 25b of the torsion coil spring 25 so as to be bent in a substantially U shape toward the lower side in the figure. The engaging portion 25c is configured to be separated from the stopper 27 described above in the “initial rotation section” as shown in FIG. 1a, but immediately after entering the “drive rotation section” from the “initial rotation section”, That is, immediately after the gear portion 21a of the toothless gear 21 described above meshes with the drive gear 23, it abuts on the stopper 27 as shown in FIG. It is configured to be reliably separated from the 25 side.

  As described above, in this embodiment, the rotational biasing force by the torsion coil spring 25 as the biasing means is loaded on the toothless gear 21 only at a necessary timing, and the “rotation driving section” in which the rotational biasing force by the torsion coil spring 25 is unnecessary. Then, the rotational biasing force of the torsion coil spring 25 does not act on the missing gear 21. Therefore, the load stress from the torsion coil spring 25 to the toothless gear 21 is minimized, and the arrangement space of the torsion coil spring 25 is made smaller than that of the conventional coil spring (see FIG. 4). It has become.

  In particular, in the present embodiment, the torsion coil spring 25 is employed as the urging means, and the rotation action portion 25a of the torsion coil spring 25 is in the “initial rotation section” and immediately after, and in the “final rotation section” and immediately before. The biasing means is easily formed by a torsion coil spring because it is configured to press against the rotation gear receiving pin 26 of the toothless gear 21 and press the toothless gear 21 in the sheet feeding rotation direction.

  Further, in the present embodiment, a guide portion 25b for shifting the rotation action receiving pin 26 of the toothless gear 21 to the rotation action portion 25a side is connected to the rotation action portion 25a of the torsion coil spring 25. By the guiding action of 25b, the missing gear 21 is smoothly and reliably returned to the “standby position”.

  On the other hand, in the embodiment according to FIG. 3 in which the same reference numerals are assigned to the same components as those in the above-described embodiment, a leaf spring 35 is employed as the biasing means. In other words, the rotation acting portion 35a provided on one end side (the right half side in the drawing) of the leaf spring 35 has the above-mentioned missing teeth in the “initial rotation section” and immediately after, and in the “final rotation section” and immediately before. The gear 21 is configured to press against the rotation gear receiving pin 26 and press the toothless gear 21 in the sheet feeding rotation direction.

  Further, in the present embodiment, a guide portion 35 b that abuts against the rotation receiving pin 26 of the toothless gear 21 in the “drive rotation section” is continuously provided on the other end side (the left half side in the drawing) of the plate spring 35. . The guide portion 35b is configured to come into contact with the rotation action receiving pin 26 of the toothless gear 21 from the “drive rotation section” immediately before entering the “final rotation section” described above, and the “drive rotation section”. Immediately before entering the “final rotation section”, the rotation receiving pin 26 of the toothless gear 21 is separated from the guide portion 35b and moves to the rotation operation portion 35a side. By such a guide action of the guide portion 35b, in the “final rotation section” described above, the rotation urging force in the paper feeding rotation direction (clockwise direction in the drawing) is surely applied from the rotation action portion 35a to the missing gear 21. To be granted.

  In such an embodiment, the urging means is easily formed by the leaf spring 35, and the rotation action portion 35a of the leaf spring 35 and the guide portion 35b are provided continuously. It has become easier.

  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 the above-described embodiment, a lock solenoid is used as the gear lock means, but various other lock means can be used.

  Further, the biasing means of the present invention is not limited to the above-described embodiment, and other various spring means and various biasing means other than the spring means can be adopted.

  Furthermore, although the above-described embodiment is an embodiment in which the present invention is applied to a printer, any apparatus can be applied as long as an apparatus for feeding a sheet-like recording material is employed. .

  The above-described incisor gear driving mechanism according to the present invention can be widely applied to an apparatus having an apparatus for feeding a sheet-like recording material, including an image forming apparatus such as a printer.

It is side surface explanatory drawing showing the principal part schematic structure of the incision gear drive mechanism in one Embodiment of this invention, and showing the state of each rotation stage. It is side explanatory drawing showing the example schematic structure of the printer to which this invention is applied. It is side surface explanatory drawing showing the principal part schematic structure of the incision gear drive mechanism in other embodiment of this invention. It is a side explanatory drawing showing the outline structure of the principal part of the conventional incision gear drive mechanism, and showing the state of each rotation stage.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Laser printer 12 Process cartridge 13 Paper feed cassette 13a Paper feed roller 13b Paper feed drive shaft P Recording paper (sheet-like recording material)
21 gearless gear 21a gear part 21b non-gear part 21c annular body part 21d engagement step part 22 rotary drive shaft 23 drive gear 24 lock solenoid (gear lock means)
24a Flapper 24a1 Tip locking portion 24a2 Main body portion 24c Coil spring 24d Electromagnetic action portion 25 Torsion coil spring (biasing means)
25a Rotating action part 25b Guide part 25c Engaging part 26 Rotating action receiving pin 27 Stopper 35 Leaf spring (biasing means)
35a Rotating action part 35b Guide part

Claims (6)

A toothless gear having a non-gear portion provided so as to cut out a part of the gear portion provided along the outer peripheral edge over an appropriate central angle range;
A drive gear that meshes with the gear portion of the toothless gear and rotationally drives the toothless gear;
Urging means for urging the toothless gear in the rotational drive direction;
Gear locking means for engaging the segmented gear and holding the segmented gear in a standby position;
In the toothless gear drive mechanism with
The urging means urges the missing tooth gear to be held by the gear locking means when the missing tooth gear is in the standby position, while the missing tooth when the missing tooth gear meshes with the drive gear. A missing gear drive mechanism characterized in that the gear is not biased. The biasing means is a torsion coil spring,
The rotation action portion extending from one end side of the torsion coil spring is configured to urge the action receiving portion of the missing tooth gear so as to press the missing tooth gear in the rotation direction at the standby position. The missing gear drive mechanism according to claim 1, wherein: The rotation action part of the torsion coil spring is continuously provided with a guide part that comes into contact with the action receiving part of the toothless gear in the drive rotation section of the toothless gear,
The guide portion is formed such that when entering the standby position from the drive rotation section, the action receiving portion of the toothless gear is detached from the guide portion and moves to the spring acting portion side. The missing gear drive mechanism according to claim 2, wherein: The urging means comprises a leaf spring;
The rotation action portion provided on one end side of the leaf spring is configured to urge the action receiving portion of the missing tooth gear so as to press the missing tooth gear in the rotation direction at the standby position. The missing gear drive mechanism according to claim 1. On the other end side of the leaf spring, a guide portion that abuts against the action receiving portion of the toothless gear in the drive rotation section of the toothless gear is continuously provided,
The guide portion is formed such that when entering the standby position from the drive rotation section, the action receiving portion of the partial gear is detached from the guide portion and moves to the rotation action portion side. The missing gear drive mechanism according to claim 4, wherein: An image forming apparatus comprising the sheet-shaped recording medium sheet feeding device including the toothless gear driving mechanism according to any one of claims 1 to 5.

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