JP2014164256A - Drive transmission device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To determine a position of a tooth-chipped gear with high accuracy even if a position of a rotation regulating member is not fixed.SOLUTION: A drive transmission device includes a rotation regulating member including a regulating surface that is brought into contact with a contact part to regulate the rotation of a tooth-chipped gear. The rotation regulating member is rotatably provided around a predetermined rotation center to be capable of taking a regulating position to regulate the rotation of the tooth-chipped gear and a non-regulating position not to regulate the rotation of the tooth-chipped gear. The regulating surface of the rotation regulating member is a concave shape and has a cross section in a shape of a circular arc of a circle around the predetermined rotation center.

Description

  The present invention relates to a drive transmission device used in a contact / separation mechanism provided in an image forming apparatus.

  In the configuration of the drive transmission device using the chipped gear provided in the conventional image forming apparatus, the rotation control member that positions the chipped gear in a predetermined rotational phase slides on the cam portion provided in the chipped gear. However, the chipped gear was energized in the radial direction. At the time of the rotation of the chipped gear, the rotation control member was operated until it directly hit the engaging portion provided on the cam portion of the chipped gear (for example, Patent Document 1).

  9 and 10 are diagrams showing a conventional drive transmission device. 9A is a front view of the drive transmission device, FIG. 9B is a top view of the drive transmission device, FIG. 10A is a rear view of the drive transmission device, and FIG. It is a perspective view of the chipped gear of a transmission device.

  As shown in FIGS. 9 and 10, the rotation control member 54 is biased so as to directly abut in the radial direction of the chipped gear 52.

  Next, the operation of the drive transmission device shown in FIGS. 9 and 10 will be described.

  The chipped gear 51 and the chipped gear 52 are arranged in parallel on the same axis. Then, the solenoid flapper 531 is locked to a locking claw 512 provided on the chipped tooth gear 51 by urging each other by a charge spring (not shown) provided inside the chipped gear.

  Normally, drive transmission is not performed because the chipped portions of both chipped gears face the drive gear 55 connected to the drive source. However, when the solenoid flapper 531 is operated to release the latched state of the latching claw 512, the chipped gear 51 becomes rotatable and is rotated by the biasing force of the charge spring 59 to drive the chipped gear 51. It becomes possible to engage with the gear 55.

  On the other hand, the missing tooth gear 52 has an abutting portion (non-rotating portion) that abuts against each other at a predetermined rotational phase provided on the missing tooth gear 51 and the missing tooth gear 52 immediately after the driving force is transmitted from the driving gear 55 to the missing tooth gear 51. And the chipped gear 52 rotates with the chipped gear 51.

  At this time, although the rotation control member 54 is engaged with the engagement groove 522 and the rotation of the chipped gear 52 is restricted, the rotation control member 54 is forcibly released by the rotational force of the chipped gear 51 and rotates. continue. It should be noted that when both chipped gears are rotating, the rotational phases of the chipped portions are different from each other, and either gear is always meshed with the drive gear 55.

  Thereafter, both chipped gears rotate to a phase where the chipped portion is opposed to the drive gear 55 by the driving force transmitted from the drive gear 55. When the chipped portion 511 of the chipped gear 51 again faces the drive gear 55, the drive transmission from the drive gear 55 is cut off. However, the rotation continues due to the rotational force of the chipped gear 52 that continues to transmit drive from the drive gear 55 via the charge spring 59, and the solenoid flapper 531 locks on the locking claw 512 and stops rotating. To do.

  Subsequently, when the chipped portion 521 of the chipped gear 52 faces the drive gear 55, the rotation control member 54 rotates by the rotational force generated by urging and sliding down the inclined surface 524 of the cam portion provided on the chipped gear. Subsequently, the rotation control member 54 engages with the engagement groove 522 and stops rotating.

JP 2006-184422 A

  However, the conventional drive transmission device has the following problems when the rotation control member 54 of the chipped gear 52 is engaged with the engagement groove 522.

  First, the position of the chipped gear 52 is determined by stopping the rotation of the chipped gear by the rotation restricting member 53 engaging with the engaging groove 522. Therefore, the position of the chipped gear 52 varies depending on the position of the rotation control member 54.

  Also, in FIG. 10A, when a load is generated that rotates the chipped gear 52 from the output gear 116 in the clockwise direction, the rotation control member 54 may be pushed away, and drive control may become impossible. There is also a problem that sudden sound is generated when the rotation control member 54 is engaged with the engagement groove 522.

  The present invention has been made in view of the above problems, and its object is to determine the position of the chipped gear with high accuracy, and to stably hold the load even when a load is generated from the output side, thereby reducing noise. Another object of the present invention is to provide a drive transmission device having a chipped gear positioning mechanism.

  In order to achieve the above object, a drive transmission device according to the present invention is a drive transmission device that transmits a driving force from a driving source, the driving gear rotating by receiving the driving force from the driving source, and the driving gear. A gear portion that can mesh with the drive gear, a missing tooth portion that cannot mesh with the drive gear, a contact portion for restricting rotation, and the missing tooth portion of the missing gear. A biasing means for biasing the chipped gear to rotate to a position where the gear portion meshes with the driving gear when in the position facing the driving gear; A rotation restricting member having a restricting surface for restricting the rotation of the tooth gear; and an output gear for transmitting the rotational force of the chipped gear to the outside, wherein the rotation restricting member restricts the rotation of the chipped gear. Control position and rotation of the chipped gear is not restricted It is provided so as to be rotatable around a predetermined rotation center so as to be able to take a control position, and the restriction surface is a concave shape and a cross section is a circle centered on the predetermined rotation center It is characterized by a circular arc shape.

  In the drive transmission device of the present invention, the rotation restricting member for restricting the rotation of the chipped gear is provided so as to be rotatable around a predetermined rotation center. The regulating surface provided on the rotation regulating member for regulating the rotation of the chipped gear by contacting the contact portion of the chipped gear has a concave shape and the cross section is a circle centered on the predetermined rotation center. The arc shape.

  For this reason, even if the position of the rotation restricting member varies somewhat, the contact portion is always pressed in the direction of the predetermined rotation center, so that the position of the chipped gear can be determined regardless of the position variation of the rotation restricting member. . Even when a load force from the output portion is applied, the rotation restricting member always presses the contact portion in the direction of the predetermined rotation center. It is possible to prevent the mismatch.

1 is an explanatory cross-sectional view illustrating a configuration of an image forming apparatus according to a first embodiment of the present invention. FIG. 2 is a perspective view of a secondary transfer unit of the image forming apparatus illustrated in FIG. 1. FIG. 3 is an explanatory diagram of a contact / separation mechanism of a secondary transfer roller of a secondary transfer unit illustrated in FIG. 2. It is explanatory drawing of a structure of the chipped gear of the secondary transfer part shown in FIG. It is a figure explaining operation | movement of the chipped gear shown in FIG. It is explanatory drawing of a structure of the chipped gear of 2nd Embodiment of this invention. It is a figure which shows the internal structure of the chipped gear of 2nd Embodiment of this invention. It is explanatory drawing of operation | movement of the chipped gear of 2nd Embodiment of this invention. It is explanatory drawing of the chipped gear which shows the conventional drive control apparatus. It is explanatory drawing of the chipped gear which shows the conventional drive control apparatus.

  A case where the present invention is applied to an electrophotographic full-color laser beam printer will be described below with reference to the drawings. However, the dimensions, materials, shapes, and relative arrangements of the components described in the following embodiments can be appropriately changed depending on the configuration of the apparatus to which the present invention is applied and various conditions, and the scope of the present invention. Are not limited to the following embodiments.

<First Embodiment>
(Overall configuration of image forming apparatus)
First, the overall configuration of the image forming apparatus will be described.

  FIG. 1 is a schematic cross-sectional view of the entire image forming apparatus of the present embodiment.

  As shown in FIG. 1, the printer 100 includes a printer main body 101, and the printer main body 101 is provided with an image forming unit 102 and a sheet feeding device 103 that feeds a sheet S to the image forming unit 102. .

  In the image forming unit 102, a photosensitive drum 10, a rotary developing device 12, a laser exposure optical system 20, and the like are disposed.

  The rotary developing device 12 has four color developing devices, a black developing device, a yellow developing device, a magenta developing device, and a cyan developing device integrated with a toner cartridge. The rotary developing device 12 rotates in the clockwise direction and can move a developing device of a desired color to a developing position facing the photosensitive drum 10 when necessary.

  Further, the image forming unit 102 transfers the toner image from the transfer belt 11 to the sheet S, and an endless transfer belt 11 that transfers the multicolor image to the sheet S after transferring and forming the four color toner images. A secondary transfer unit 13 is provided.

  In the secondary transfer unit 13, the secondary transfer roller 13 a sandwiches the sheet S between the transfer belt 11 and the toner image on the transfer belt 11 is secondarily transferred to the sheet S.

  On the downstream side of the secondary transfer unit 13, a fixing unit 14 that fixes an unfixed image on the sheet S and a discharge roller pair 15 that discharges the sheet S on which the image is fixed to the outside of the printer main body are provided. .

  When an image forming signal is output from a control device (not shown) provided in the printer main body 101, a light image of the first color converted into an optical signal from the laser exposure optical system 20 is projected onto the photosensitive drum 10. . At this time, the surface of the photosensitive drum 10 is charged in advance, and an electrostatic latent image is formed on the surface of the photosensitive drum 10 by projecting an optical image.

  Next, the electrostatic latent image is developed by the developing unit corresponding to the selected first color among the plurality of developing units arranged in the rotary developing unit 12, and the first color toner image is formed on the photosensitive drum. It is formed. Thereafter, the toner image formed on the photosensitive drum 10 is transferred onto the transfer belt 11. Here, in the color mode, the transfer belt 11 to which the toner image is transferred further rotates so that the next toner image is formed and transferred. During this time, the rotary developing device 12 rotates the next designated color developing device by 90 ° so as to face the photosensitive drum 10, and prepares to develop the next electrostatic latent image.

  The photosensitive drum 10 after the primary transfer is repeated, as with the first color, the second color, the third color, the fourth color and the latent image, development, and primary transfer, and the toner images of the respective colors are sequentially superimposed on the transfer belt 11. To go. Further, when the first to third color toners are superimposed on the transfer belt 11, the secondary transfer roller 13 a is separated from the transfer belt 11 by a drive control device (drive transmission device) described later in detail. Before starting to write the fourth color, the secondary transfer roller 13a and the transfer belt 11 are brought into contact with each other by the drive control device.

  On the other hand, in parallel with such an image forming operation, the sheet S is sent out from the sheet feeding device 103 and sent to the secondary transfer unit 13 at a timing coincident with the toner image on the transfer belt 11. The sheet S sent to the secondary transfer unit 13 is conveyed to the fixing unit 14 after the toner image is transferred by the secondary transfer roller 13a. Thereafter, the unfixed transfer image is permanently fixed on the sheet S by being heated and pressed by the fixing unit 14. The sheet S on which the image has been fixed in this way is discharged onto the upper surface of the printer main body 101 by the discharge roller pair 15. 16 is discharged.

(Configuration of drive control device)
Next, the drive control device will be described.

  FIG. 2 is a perspective view of the secondary transfer unit 13. The transfer belt 11 is rotated in the A direction by a driving roller (not shown). Further, there is a driven roller 13b that is driven to rotate in contact with the transfer belt 11, and transfer cams 201 are provided at both ends on the same axis. Further, a transfer gear 203 is provided at one end of the driven roller 13b. The transfer cam 201 and the transfer gear 203 are configured to be integrally rotatable, but they and the driven roller 13b are configured to slide and rotate. That is, the rotational force of the driven roller 13 b is configured not to be transmitted to the transfer cam 201 and the transfer gear 203.

  The drive gear 207 is connected to a drive source (not shown). Then, the drive of the drive gear 207 is transmitted to the chipped gear 206. A driving force is transmitted from a small gear 205 (output unit) integrally configured as a chipped gear 206 and a step gear to an idler gear 204 outside the drive control device, so that the transfer cam 201 and the transfer gear 203 rotate. Has been.

  On the other hand, cam levers 202 are slidably rotated at both ends of the rotation shaft of the secondary transfer roller 13a. The cam lever 202 is held by a secondary transfer folder (not shown) so as to be movable only in the direction in which the secondary transfer roller 13a contacts the driven roller 13b.

  One end of the two-roll spring 211 is in contact with the cam lever 202, and the other end is in contact with the two-roll spring receiver 210. The two-roll spring receiver 210 is provided in a secondary transfer folder (not shown). In the state shown in FIG. 2, the transfer cam 201 moves the cam lever 202 away from the driven roller 13 b against the spring pressure of the second rolling spring 211 to separate the secondary transfer roller 13 a from the transfer belt 11.

(Secondary transfer roller contact / separation operation)
Next, the contact / separation mechanism of the secondary transfer roller will be described.

  3A and 3B are cross-sectional views of the contact / separation mechanism. FIG. 3A shows a state where the secondary transfer roller is separated, and FIG. 3B shows a state where the secondary transfer roller 13a is in contact. Is shown.

  As shown in these drawings, the secondary transfer roller 13a is pressed in the axial direction of the driven roller 13b by the second rolling spring 211. The transfer cam 201 includes a long shaft portion 201a having a radius larger than the radius of the driven roller 13b and a short shaft portion 201b having a radius smaller than the radius of the driven roller.

  The cam lever 202 has a lever radius portion 202a having a radius larger than the radius of the secondary transfer roller 13a in the driven roller direction. As shown in FIG. 3A, the secondary transfer roller 13a and the driven roller 13b can be separated by contacting the long shaft portion 201a and the lever radius portion 202a.

  On the other hand, as shown in FIG. 3B, when the phase of the transfer cam 201 is changed by a missing tooth mechanism described later and the short shaft portion 201b comes closest to the secondary transfer roller 13a, the transfer cam 201 and the cam lever 202 come into contact with each other. Disappear. For this reason, the secondary transfer roller 13a and the driven roller 13b come into contact with each other by the two-roll spring 210.

  This contact / separation control is switched by a missing tooth mechanism. In the missing tooth mechanism, the reduction gear ratio between the missing tooth gear 206 and the transfer gear 203 is 2: 1. When the missing tooth gear 206 makes one rotation, the transfer gear 203 makes 1/2 rotation. For this reason, the transfer cam 201 integrally formed with the transfer gear 203 rotates 180 °, and the position of FIG. 3A and FIG. 3B changes every time the chip gear 206 rotates once. It will be switched alternately.

(Configuration of chipped gear)
Next, the missing gear which is a characteristic part of the present invention will be described.

  FIG. 4 is a diagram showing the configuration of the chipped gear 206 and its peripheral portion. 4 (a) is a front view, FIG. 4 (b) is a perspective view, and FIG. 4 (c) is a front view showing a state in which the position of the cam lever varies.

  As shown in FIG. 4A, the missing gear 206 has a gear portion 206m that can mesh with the drive gear 207 and a missing tooth portion 206n that cannot mesh.

  As shown in FIG. 4B, the chipped gear 206 is cantilevered by a chipped gear shaft 206c. The chipped gear 206 is provided with a chipped spring receiver 206b. One of the chipped gear springs 209 is supported by the chipped tooth spring receiver 206 b and the other is supported by a boss 401 fixed to the printer main body 101.

  The chip gear 206 is biased counterclockwise by the chip gear gear 209 at the position shown in FIG. The cam lever 208 (rotation restricting member) is rotatably supported by a lever fulcrum 208a (predetermined rotation center) and has a concave contact portion 208b (regulating surface). The concave shape of the abutting portion 208b is a shape inside a circular arc whose section is centered on the lever fulcrum 208a. The abutting portion 208b is for abutting a chipped gear boss 206a provided on the chipped gear 206 to determine the position of the chipped gear 206.

  In a state where the chipped gear 206 is at the home position shown in FIG. 4A, the cam lever 208 abuts and supports the chipped gear 206 urged counterclockwise by the chipped gear spring 209, and is stable. The chipped gear 206 is held. That is, the rotation of the chipped gear 206 is restricted when the chipped gear boss 206a contacts the contact portion 208b.

  The chipped gear boss 206a has a circular cylindrical shape with a cross section whose radius is smaller than the radius of the concave circular arc of the contact portion 208b. The contact part 208b can be contacted.

  Further, even when the cam lever position varies as shown in FIG. 4C, the position of the abutment gear 206 in the rotation direction of the abutment gear 206 does not change in the contact portion 208 b that supports the missing tooth gear 206. This is because the cross section of the abutting portion 208 b is formed in a circular concave shape centering on the rotation fulcrum of the cam lever 208. This is because, even when the cam lever 208 fluctuates as shown in FIG. 4C due to the concave shape, a force is always applied to the chipped gear boss 206a in the direction of the lever fulcrum 208a. Further, the chipped gear boss 206a has a circular cylindrical shape whose cross section is smaller than the radius of the concave arc of the contact portion 208b, whereby the position of the chipped gear 206 can be determined more stably. .

(Operation of chipped gear)
The operation of the chipped gear 206 will be described.

  FIG. 5 is a plan view showing the state of the chipped gear 206 and its surroundings. FIG. 5A is a diagram showing the home position of the chipped gear 206. FIG. 5B is a diagram illustrating a state where the cam lever 208 is retracted and the chipped gear 206 starts to mesh with the drive gear 207 from the home position. FIG. 5C is a diagram showing a state in which the chipped gear 206 is rotated by the drive gear 207. FIG. 5D is a diagram illustrating a state where the cam lever 208 has returned to the contact position. FIG. 5E is a diagram showing a state in which the chip gear 206 has returned to the home position shown in FIG. 5E due to the biasing force of the chip gear spring 209.

  As shown in FIG. 5 (a), the cam lever 208 is moved from the home position to a position where the chipped gear boss 206a and the contact portion 208b are in contact (regulated position) to a position where it is not in contact (non-regulated position). Rotate.

Then, the chipped gear 206 jumps into the drive gear 207 by the biasing force of the chipped gear spring 209 as shown in FIG. Then, the drive gear 207 is rotated in the clockwise direction T, and as shown in FIG. 5C, the drive gear 207 is driven and the chipped gear 206 is rotated counterclockwise.

  5D is further rotated, and the cam lever 208 is rotated to a position where it can come into contact with the chipped gear boss 206a until the chipped gear 206 is rotated once by an actuator (not shown). Further, when the chipped gear 206 further rotates, the driving of the drive gear 207 is cut by the chipped portion, and the chipped gear 206 is returned to the home position shown in FIG. 5E by the biasing force of the chipped gear spring 209.

  As shown in FIGS. 5 (a) and 5 (e), when the missing gear 206 is in the home position, the missing gear boss 206a and the abutting portion 208b are in contact with each other even if the cam lever 208 varies in position. The position of the chipped gear 206 can be determined stably.

  Further, if the chipped gear boss 206a is supported by the contact portion 208b, even if a counterclockwise load is applied to the chipped gear 206 due to disturbance, the load is applied in the direction of the lever fulcrum 208a of the cam lever 208. The force vector is suitable. For this reason, the cam lever 208 loses its load and the lever is pushed down, and the chipped gear 206 can be prevented from jumping into the drive gear 207.

Second Embodiment
Next, an image forming apparatus according to another embodiment of the present invention will be described.

  Parts that are the same as or similar to those in the first embodiment are given the same reference numerals, and redundant descriptions are omitted. In this embodiment, the image forming apparatus is the same as the image forming apparatus shown in FIGS. 1, 2, and 3 of the first embodiment, and only different parts will be described below.

(Configuration of chipped gear)
FIG. 6 is a diagram showing a configuration of a chipped gear and its surroundings. FIG. 6A is a front view, and FIG. 6B is a perspective view.

  As shown in these drawings, in the present embodiment, the chipped gear 601 (second chipped gear) and the chipped gear 602 (first chipped gear) are arranged side by side on the same axis.

  In addition, the chipped gear 601 includes a second gear portion that can mesh with the drive gear 207 and a second chipped portion that cannot mesh with the drive gear 207, similarly to the chipped gear 206 shown in FIG. 4 of the first embodiment. Have. Similarly, the chipped gear 602 has a first gear portion that can mesh with the drive gear 207 and a first chipped portion that cannot mesh.

  A chipped gear spring 604 (chipped gear urging means) is installed inside the chipped gear 601 and the chipped gear 602. The chipped gear spring 604 has one end received by the chipped gear 601 and the other end received by the chipped gear 602. The chipped gear spring 604 is a compression spring and always biases the chipped gear 601 in the clockwise direction P and the chipped gear 602 in the counterclockwise direction Q. That is, the chipped gear 601 and the chipped gear 602 are urged in directions to rotate in directions opposite to each other.

  The chipped gear 601 is provided with a chipped gear boss 601a (second contact portion) for contacting the cam lever 603 (second rotation restricting member).

  The chipped gear boss 601a has a circular cylindrical shape whose cross section is smaller than the radius of the concave arc of the abutting portion 603b. When the cam lever 603 takes a restricting position, the cylindrical outer peripheral surface is The contact portion 603b can be contacted.

  The cam lever 603 is rotatably supported by a lever fulcrum 603a and has a concave contact portion 603b. The concave shape of the contact portion 603b is an arc shape whose cross section is centered on the lever fulcrum 603a. The abutting portion 603b is for abutting a chipped gear boss 601a provided on the chipped gear 601 to determine the position of the chipped gear 601.

  The cam lever 603 is urged clockwise around a lever fulcrum 603a by a cam lever spring 605 (regulating member urging means), and the position of the cam lever 603 is determined by a cam lever stopper 606 (positioning contact portion). Since the chipped gear 601 is urged clockwise by the chipped gear spring 604, the position is stably determined in a state where the chipped gear 601 is in contact with the contact portion 603b.

  Further, the cam lever 603 is provided with a contact portion 603c (sliding surface). The chipped gear 601 rotates and the chipped gear boss 601a abuts against the abutting portion 603c and is configured to push the cam lever 603 in the direction of the cam lever spring 605 while sliding.

  A solenoid lever 607a (first rotation restricting member) of the solenoid 607 is in contact with the chipped gear 602 and a chipped gear receiving portion 602a (first contact portion), and the chipped gear spring 604 counterclockwise. The energized chipped gear is stably held.

  FIG. 7 is a view showing the inside of the chipped gear 602. FIG. 7A is a diagram showing an internal state of the chipped gear 602 when the solenoid lever 607a is pulled from the state of FIG. FIG. 7B is a diagram showing an internal state when the chipped gears 601 and 602 rotate in conjunction with each other. FIG.7 (c) is a perspective view of the chipped gears 601 and 602 and its peripheral part in the state of FIG.7 (b).

  As shown in these drawings, the partial gear spring receiver 601b and the partial gear receivers 601c and 601d are parts that move integrally with the partial gear 601. When the solenoid lever 607 a is pulled by the solenoid 607 (when the restriction is released), the chipped gear 601 does not move because it is held by the cam lever 603, but the chipped gear 602 is counterclockwise due to the biasing force of the chipped gear spring 604. Rotate around. Then, the meshing portion of the chipped gear 602 meshes with the drive gear 207, receives the driving force, and further rotates clockwise.

  After rotating for a while, as shown in FIG. 7B, chipped gear receivers 601 c and 601 d that are part of the chipped gear 601 and chipped gears that are part of the chipped gear 602, inside the chipped gear 602. The receivers 602c and 602d come into contact with each other. The chipped gear 602 receives the driving force from the drive gear 207 and rotates counterclockwise, so that the driving force is transmitted to the chipped gear receivers 601c and 601d through the chipped gear receivers 602c and 602d. The chipped gear receivers 601c and 601d and the chipped gear receivers 602c and 602d constitute interlocking means.

  The chipped gear 601 receives a clockwise biasing force from the chipped gear spring 604, but since the transmission force from the drive gear 207 is larger, the chipped gear 601 follows the chipped gear 602 and counterclockwise. Rotate around.

  The chipped gear 601 is provided with an output gear similar to the small gear 205 shown in FIG. 3 of the first embodiment that rotates integrally with the chipped gear 601, but is not shown.

(Operation of chipped gear)
Next, the operation of the chipped gear will be described.

  FIG. 8 is a diagram for explaining the operation of the chipped gears 601 and 602.

  8A is a plan view showing a state in which the chipped gear boss 601a is in contact with the contact portion 603c that is the slope of the cam lever 603, and FIG. 8B is a perspective view in the state of FIG. 8A. It is.

  FIG. 8C is a plan view showing a state in which the chipped gear boss 601a pushes while sliding on the contact portion 603c, and FIG. 8D is a perspective view in the state of FIG. 8C. It is.

  FIG. 8E is a plan view showing a state immediately before the driving force from the driving gear 207 is interrupted, and FIG. 8F is a perspective view in the state of FIG. 8E.

  FIG. 8 (g) is a plan view showing a state where the chipped gears 601 and 602 have returned to the home position, and FIG. 8 (h) shows a perspective view in the state of FIG. 8 (g). .

  First, as shown in FIG. 6, the chipped gears 601 and 602 are in the home position and are not meshed with the drive gear 207.

  When the solenoid lever 607a is pulled by the electric force of the solenoid 607, the chipped gear 602 is rotated counterclockwise from the home position shown in FIG. 6 by the chipped gear spring 604. The chipped gear 602 meshes with the driving gear 207 to receive a driving force, and the driving force further rotates counterclockwise.

  Next, as shown in FIG. 7B, the chipped gear receivers 602c and 602d of the chipped gear 602 press the chipped gear receivers 601c and 601c of the chipped gear 601. It follows 602 and rotates counterclockwise.

  After rotating clockwise for a while, the chipped gears 601 and 602 are in a state as shown in FIGS. 8A and 8B, and the chipped gear boss 601a contacts the contact portion 603c. When the chipped gear 601 applies a force by the driving force from the driving gear 207 while the chipped gear boss 601a slides on the contact portion 603c, the cam lever 603 rotates counterclockwise.

  Then, the solenoid 607 moves the solenoid lever 607a to a position where it can collide with the chipped gear receiving portion 602a.

  Thereafter, as shown in FIGS. 8C and 8D, the chipped gear receiver 602a contacts the solenoid lever 607a. In this state, the missing gear 602 receives no driving force from the driving gear 207 due to the missing tooth portion.

  The chipped gear 602 is biased counterclockwise by the chipped gear spring 604 inside the chipped gear 602, and is stably held by receiving the biasing force by the solenoid lever 607a.

  In the state of FIG. 8C and FIG. 8D, the chipped gear 601 is still receiving the driving force from the driving gear 207 and rotating clockwise.

  Thereafter, as shown in FIGS. 8 (e) and 8 (f), in the state immediately before the driving force from the driving gear 207 is interrupted, the chipped gear 601 has the cam lever protrusion 603d of the cam lever 603 replaced the chipped gear boss 601a. Energize counterclockwise. As a result, even if the driving force from the drive gear 207 is interrupted, the chipped gear 601 can be rotated clockwise, and the chipped gear 601 is brought to the home position as shown in FIGS. 8 (g) and 8 (h). Can be moved.

  The cam lever 603 has a concave abutting portion 603b. The concave shape of the abutting portion 603b is a circular arc whose section is centered on the lever fulcrum 603a. 601a abuts to determine the position of the missing gear 601. For this reason, even if the position of the cam lever 603 varies somewhat, the position of the chipped gear 601 can be determined stably.

(Composition of cam lever stopper)
Further, since the cam lever 603 is positioned by the cam lever stopper 606, the cam lever 603 and the cam lever stopper 606 come into contact with each other when the state shown in FIG. 8E shifts to the state shown in FIG. May occur.

  Therefore, by forming the cam lever stopper 606 with a cushioning elastic member or the like, it is possible to reduce the sudden sound generated when the cam lever 603 and the cam lever stopper 606 come into contact with each other. There is a possibility that the position of the cam lever 603 may change due to variations in the thickness of the elastic member. However, in the present embodiment, the concave shape of the contact portion 603b is an arc shape whose cross section is centered on the lever fulcrum 603a. Therefore, even if the position of the cam lever 603 changes, the position of the missing gear 601 is stable. It becomes possible to decide.

DESCRIPTION OF SYMBOLS 10 ... Photosensitive drum 11 ... Transfer belt 12 ... Rotary developing device 13a ... Secondary transfer roller 100 ... Laser printer 101 ... Printer main body 102 ... Image forming part 201 ... Transfer cam 202 ... Cam lever 203 ... Transfer gear 205 ... Small gear 206 ... Missing Teeth gear 206a ... Lack tooth gear boss 206b ... Lack tooth gear holder 206c ... Lack tooth gear shaft 207 ... Drive gear 208a ... Lever fulcrum 208b ... Abutting portion 209 ... Lack tooth gear spring 401 ... Boss 601 and 602 ... Lack tooth gear 601a ... Chip tooth gear boss 601b ... chip tooth gear spring receiver 601c, 601d ... chip tooth gear receiver 602a ... chip tooth gear receiver 603 ... cam lever 604 ... chip tooth gear spring 605 ... cam lever spring 606 ... cam lever stopper 607 ... solenoid 607a ... solenoid lever S ... Sheet

Claims (13)

A drive transmission device for transmitting a driving force from a drive source,
A driving gear that rotates in response to a driving force from the driving source;
A gear portion that can be engaged with the drive gear, a missing tooth portion that cannot be engaged with the drive gear, and a missing tooth gear provided with a contact portion for restricting rotation;
Biasing means for biasing the chipped gear to rotate to a position where the gear part meshes with the drive gear when the chipped part of the chipped gear is in a position facing the drive gear; ,
A rotation regulating member having a regulating surface that abuts on the abutting portion and regulates the rotation of the chipped gear; and an output unit for transmitting the rotational force of the chipped gear to the outside.
The rotation restricting member rotates around a predetermined rotation center so as to be able to take a restricting position that restricts the rotation of the chipped gear and a non-regulating position that does not restrict the rotation of the chipped gear. Is possible,
The drive transmission device according to claim 1, wherein the restriction surface has a concave shape and a cross-section having a circular arc shape with the predetermined rotation center as a center.   The said contact part has a column shape, and when the said rotation control member takes the said control position, the said cylindrical outer peripheral surface can contact the said control surface. Drive transmission device. When the chipped portion of the chipped gear is in a position facing the drive gear, the regulating surface of the rotation regulating member comes into contact with the outer peripheral surface of the contacting portion, thereby While restricting rotation,
In the state where the rotation restricting member restricts the rotation of the chipped gear at the restricting position, the rotation restricting member is rotated to move to the non-regulated position, so that the biased gear is moved by the biasing means. The drive transmission device according to claim 2, wherein the gear portion meshes with the drive gear and a driving force is applied to the chipped gear from the drive gear.   After the rotation restricting member moves from the restricting position to the non-restricting position and before the chipped gear rotates once, the non-regulating position moves to the restricting position, and the restricting surface of the restricting member The drive transmission device according to claim 3, wherein the drive transmission device is in contact with the outer peripheral surface of the contact portion.   The biasing means is an elastic member having one end attached to the chipped gear and the other end fixed to the outside of the chipped gear. The drive transmission device according to one item. A drive transmission device for transmitting a driving force from a drive source,
A driving gear that rotates in response to a driving force from the driving source;
A first chip portion provided with a first gear portion that can mesh with the drive gear, a first chipped portion that cannot mesh with the drive gear, and a first contact portion for restricting rotation. Tooth gear,
A second gear portion that can mesh with the drive gear, a second chipped portion that cannot mesh with the drive gear, and a second abutting portion for restricting rotation are provided, A second chipped gear arranged coaxially with the chipped gear;
When the first missing tooth portion and the second missing tooth portion are in positions facing the drive gear, the first missing gear is moved to a position where the first gear portion meshes with the drive gear. A chipped gear biasing means for biasing so as to rotate,
A first rotation regulating member that abuts on the first abutting portion and regulates and releases the rotation of the first chipped gear at a predetermined timing;
When the rotation of the first chipped gear is shifted from the state where the rotation of the first chipped gear is restricted by the first rotation restricting member, the rotation of the first chipped gear is accompanied by the rotation of the first chipped gear. Interlocking means for interlockingly rotating the second chipped gear so as to mesh the second gear portion with the drive gear;
A second rotation restricting member provided with a restricting surface for restricting rotation of the second chipped gear in contact with the second abutting portion, and for outputting the rotational force of the second chipped gear to the outside. An output unit,
The second rotation restricting member is predetermined so as to be able to take a restricting position that restricts the position of the second chipped gear and a non-regulating position that does not restrict the placement of the second chipped gear. It is provided to be rotatable around the rotation center of
The drive transmission device according to claim 1, wherein the restriction surface has a concave shape and a cross-section having a circular arc shape centering on the predetermined rotation center.   The second abutting portion has a cylindrical shape, and when the second rotation restricting member takes the restricting position, the outer peripheral surface of the cylindrical shape can contact the restricting surface. The drive transmission device according to claim 6. Restriction member urging means for urging the two rotation restriction members to move from the non-regulation position to the restriction position;
A positioning contact portion for restricting movement in a direction in which the second rotation restricting member is urged by the restricting member urging means at a predetermined position;
8. The drive transmission device according to claim 6, wherein the positioning contact portion includes an elastic member at a portion in contact with the second rotation restricting member. The second rotation restricting member is in a non-regulated position direction against the urging force of the restricting member urging means when the second abutting portion comes into contact with and slides. Has a sliding surface to move to
9. The second contact portion comes into contact with the restriction surface of the second rotation restricting member again after the second contact portion slides on the sliding surface. Drive transmission device.   The drive transmission device according to claim 9, wherein the chipped gear biasing unit biases the first chipped gear and the second chipped gear in opposite directions.   11. The drive transmission according to claim 10, wherein the first rotation regulating member is driven by a solenoid so as to be brought into contact with and separated from a first contact portion of the first chipped gear. apparatus. The first rotation restricting member and the second rotation restricting member are respectively in a state where the first missing tooth portion and the second missing tooth portion are in positions facing the drive gear. Restricting rotation of the first chipped gear and the second chipped gear;
When the first rotation restricting member shifts from this state to the state where the first rotation restricting member does not restrict the rotation of the first chipped gear by the solenoid, the first chipped gear is urged by the chipped gear urging means. Start rotating, mesh with the drive gear and rotate further,
With the rotation of the first chipped gear, the second chipped gear rotates by the interlocking means,
After the second contact portion slides on the sliding surface of the second rotation restriction member, the second rotation restriction member is urged by the restriction member urging means, and the positioning contact portion The drive transmission device according to claim 11, wherein the second abutting portion comes into contact with the regulating surface of the second rotation regulating member again by abutting on the shaft. An image forming apparatus for forming an image on a sheet,
An image forming means for forming a toner image on the transfer belt;
A transfer roller for transferring the toner image of the transfer belt to the sheet;
The drive transmission device according to any one of claims 1 to 12,
An image forming apparatus comprising: a contact / separation mechanism that performs contact and separation operations of the transfer roller with respect to the transfer belt by a driving force output from the drive transmission device via the output unit.

Images