JP2011197294A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a drive device that includes the configuration in which where a plurality of power transmission paths from a single drive source are set, drive in the same direction is maintained in one of driving paths regardless of transmission/non-transmission of a driving force.SOLUTION: The drive device 105 is configured such that power transmission paths G and G' different from each other are set for the single drive source M and a member 9 to be driven, provided in the output positions of the power transmission paths is driven. In the drive device 105, the one power transmission path G includes a member 9 that always moves in the same direction, and the other power transmission path G' includes a member 102 that moves in an opposite direction according to the normal/reverse drive of the drive source M. The drive device 105 includes a configuration 106 for transmitting power for moving in the same direction to the member 9 located in the one power transmission path G, regardless of the normal/reverse drive of the drive source M.

Description

  The present invention relates to an image forming apparatus, and more particularly, to a driving mechanism for a shielding member intended for a detection sensor for a toner image formed on an image carrier.

  In recent years, there has been a rapid increase in demand for improvement in printing speed and higher image quality of color image forming apparatuses. In order to satisfy this demand, so-called quadruple tandem image forming apparatuses are becoming mainstream. In the quadruple tandem system, four image forming units consisting of an image carrier and a developing device are arranged facing a belt device such as a transport belt or a transfer belt (for four colors) to transfer a toner image on the image carrier. The image is sequentially transferred onto paper or a transfer belt, and a full color image can be obtained in a short time. In particular, the latter intermediate transfer system in which a toner image is transferred onto a transfer belt and then transferred onto a transfer sheet has become the mainstream in recent image forming apparatuses in order to achieve both a high printing speed and high image quality.

  On the other hand, the quadruple tandem method has a problem that color misregistration occurs unless images of four colors are accurately overlapped, resulting in a reduction in image quality. In order to solve this problem, so-called color misregistration correction means is known in which a toner image is transferred onto a transfer belt, the toner image is detected by an optical sensor, and writing timing is changed based on the detected information (for example, Patent Document 1).

  However, if the sensor is contaminated by toner or the like scattered in the machine, the detection accuracy is degraded. In order to prevent this, a configuration in which the sensor is covered with a shutter and the shutter is opened only when a toner image is detected has been proposed (for example, Patent Document 2). Patent Document 2 discloses a configuration using a solenoid as a mechanism for opening and closing the shutter.

  A single drive motor is used as the shutter opening / closing mechanism, and in the transmission path of the driving force from this motor, the drive path of the cam that opens and closes the shutter and the drive path to the registration roller are set, and the drive path to each drive path is set. A configuration has been proposed in which a one-way clutch is provided on the input side to switch the transmission direction to the drive path (for example, Patent Document 3).

  However, in order to operate the shutter opening / closing mechanism and the secondary transfer roller contact / separation mechanism, a separate mechatronic part (solenoid or brush motor) is required, which increases costs and power consumption. The addition of mechatronic parts was also disadvantageous in terms of reliability. In addition, there is a risk that the apparatus will also become larger.

  On the other hand, the configuration disclosed in Patent Document 3 has the advantage of minimizing the number of drive sources for members having different functions, but transmits power to members that should always be in an operating state using the drive sources. There is a problem that cannot be performed. In other words, the drive transmission to the shutter requires the cam phase to be set, so phase switching can be set by rotating the motor in the forward and reverse directions, but the motor can be driven in the reverse direction as in the fixing roller provided in the image forming apparatus. Regardless of the rotation, there is a possibility that power transmission to a member that needs to always maintain the rotation in the same direction cannot be performed by the stepping operation of the one-way clutch.

  An object of the present invention is to solve the problems in the conventional drive device described above, and when a plurality of power transmission paths from a single drive source are set, the same direction is maintained regardless of the drive force step in one drive path. It is an object of the present invention to provide a driving device and an image forming apparatus having a configuration in which the driving of the apparatus is maintained.

In order to achieve this object, the present invention has the following configuration.
(1) In a drive device in which different power transmission paths are set for a single drive source and drive a driven member provided at an output position of the power transmission path,
One of the power transmission paths always has a member that moves in the same direction, and the other one of the power transmission paths has a member that moves in opposite directions according to forward and reverse driving of the drive source. Each of which is configured to transmit power in a direction in which a member located in one of the power transmission paths is moved in the same direction regardless of whether the drive source is forward or reverse driven. The drive device characterized.
(2) A gear train having a plurality of gears is provided in the power transmission path, and a driving force is applied to one of the gear trains on the input side of the gear train according to the drive direction of the drive source. (1) The drive device according to (1), wherein transmission switching means for transmitting is provided.
(3) The gear train provided in one of the power transmission paths is combined with a number of gears that allow movement in the same direction regardless of the drive direction of the drive source. The drive device according to (1) or (2), which is characterized.
(4) The transmission switching means includes a swinging member that can be interlocked with the drive source, and the drive source has a swinging direction corresponding to the driving direction of the drive source on the swinging end side of the swinging member. An input gear capable of switching the meshing state with the side gear is provided, and the input gear meshes with the drive source side gear to transmit power to one of the gear trains (1) Or the drive device as described in (2).
(5) The gear at the last stage of the gear train is allowed to rotate only a predetermined amount in one of the driving directions of the driving source, and stops rotating when rotating in the direction opposite to the one direction. (4) The drive device according to (4), wherein an operating gear provided in a clutch that maintains the state is engaged.
(6) In the image forming apparatus including the driving device according to any one of claims 1 to 5,
One of the power transmission paths is provided with a fixing device having a gear that meshes with the last stage gear of the gear train, and the other of the power transmission paths has a gear positioned at the last stage of the gear train. A shutter is provided that has a working gear that is allowed to rotate in a predetermined amount in one direction by being engaged and stopped in a direction opposite to the one direction, and that can be reciprocated by selecting the rotating direction of the working gear, An image forming apparatus, wherein members provided in the fixing device are driven in the same direction regardless of a driving direction of the driving source.
(7) The image forming apparatus according to (6), wherein the shutter is a member capable of reciprocating between a position where the density detection sensor is exposed and a position where the density detection sensor is exposed to the outside.

  According to the present invention, when power is transmitted in different directions by a single drive source, regardless of the selection of the power transmission path, a member provided on a path that always needs to be driven in the same direction. Thus, the drive can be maintained by the gear train switching selection. This makes it possible to use a single drive source to perform different types of drive between a member that moves in the forward and reverse directions according to the drive direction of the drive source and a member that always moves in the same direction.

It is a figure which shows the image forming apparatus with which the drive device by this invention is applied. FIG. 2 is a schematic diagram for explaining a configuration of a process cartridge used in the image forming apparatus shown in FIG. 1. It is a figure for demonstrating the arrangement configuration of the sensor unit used for the image forming apparatus shown in FIG. 1, and its shutter device. It is a figure for demonstrating the principal part structure of the drive device by this invention. It is a figure which shows the one aspect | mode of the drive device shown in FIG. 4 is a flowchart for explaining an operation procedure of the drive device according to the present invention. It is a side view which shows the partial modification of the sensor unit shown in FIG.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram showing an image forming apparatus according to the present invention. The image forming apparatus 1 shown in FIG. 1 is juxtaposed in the direction in which a transfer belt is extended in which an image forming unit for each color is used as an intermediate transfer member. Tandem color printer.

  In FIG. 1, image forming units 2, 3, 4, and 5 for forming a plurality of color images are juxtaposed inside a housing body 1 </ b> A of the color printer 1. In FIG. 1, yellow, cyan, magenta, and black images are formed in the order in which the image forming units are assigned with the codes 2, 3, 4, and 5, respectively.

  The image forming units 2, 3, 4, and 5 are units for forming an image using toner that has a complementary color relationship with a color based on an original image or image information, and a belt having a stretching direction along the juxtaposition direction. It is arranged to face the transfer device 6 having the intermediate transfer body 6A to be used.

  The image forming units 2, 3, 4, and 5 are detachably provided on the housing body 1A of the color printer 1 and have the same configuration. The details will be described later with reference to FIG.

On the other hand, in the case main body 1A of the color printer 1, a transfer device 6 is disposed at a position facing the photoreceptor of each of the image forming units 2, 3, 4 and 5.
The transfer device 6 includes an intermediate transfer body 6A having a stretched portion along the juxtaposition direction of the image forming units 2, 3, 4 and 5, and a transfer provided at a position facing the photoconductor across the intermediate transfer body 6A. And a bias device 6B.

  Below the transfer device 6, a paper feeding device 7 is provided. The paper feeding device 7 feeds the recording paper S stored in the paper feeding cassette 7A by the feeding roller 7B, and the fed recording paper S is fed out. Is set to a transfer position for each image forming unit after the registration timing is set via the registration roller 8.

  A fixing device 9 is disposed at a position where the recording paper passes through a position where the image forming unit and the transfer device 6 are opposed to each other inside the housing main body 1A, and the toner image transferred onto the recording paper is melted by heat and pressure. It comes to wear.

  The fixed recording sheet S is discharged through a paper discharge device 10 toward a paper discharge tray 1B provided in the housing main body 1A. In FIG. 1, reference numeral 11 indicates a writing unit.

  FIG. 2 is a diagram showing the image forming unit 2 capable of forming a yellow image, but the other image forming units have the same configuration.

  In FIG. 2, the image forming unit 2 remains on the developing device 30 for processing the electrostatic latent image formed on the photoconductor 20 rotating in the direction of the arrow shown in the figure, and on the photoconductor 20 after transfer. A cleaning device 40 that collects toner is provided in the same space. The configuration of the cleaning device 40 will be briefly described. The cleaning device 40 includes cleaning blades 40A and 40B that contact the photoconductor 20 and scrape off residual toner, and a charge removing roller 40C. The toner removed from the photoconductor 20 is: It is transported toward the developer supply part 35A2 of the developing device 30 by a conveying member 40D such as a collecting screw and recycled.

  The developing device 30 includes a developing sleeve 31 that can carry a developer on the surface thereof and can carry a developer used for developing the photosensitive member 20, and a roller that is in contact with the developing sleeve 31 and is rotatably provided. The developer is stirred in the developer supply member 32, the doctor blade 33 that defines the layer thickness of the developer carried on the surface of the developing sleeve 31, and the developer supply portion 35A2 where the developer supply member 32 is located. A stirring member 34 using a rotatable paddle and the like, and a developer supply means 35 are provided.

  The developer supply means 35 is indicated by an arrow in the vicinity of the discharge port 35A1 formed in the lower part of the developer storage tank 35A corresponding to the vertically long developer storage portion disposed above the developer supply member 32. A developer replenishing member 35B that is rotatable in the clockwise direction and a rotatable developer transporting member 35C that transports the developer stored in the developer storage tank 35A toward the developer discharge port 35A1. .

  The developer replenishing means 35 reduces the load of the developer on the developer supply member 32, and as a configuration therefor, a sheet 36 integrated with the developer replenishment member 35B and the discharge port 35A1. And are used.

  On the other hand, the color printer 1 shown in FIG. 1 is provided with a density detection sensor 100 that detects a toner patch formed on the intermediate transfer body when color misregistration between images to be formed or density control is performed.

  As shown in FIG. 1, the density detection sensor 100 is provided in a sensor unit 101 disposed in the vicinity of the fixing device 9 in the intermediate transfer body 1A.

  FIG. 3 is a diagram showing the arrangement configuration of the sensor unit 101. In FIG. 3, the sensor unit 101 has a surface facing the intermediate transfer body 6A and a length along the direction perpendicular to the latitudinal direction of the intermediate transfer body 6A. A plurality of density detection sensors 100 are arranged in the direction.

  Above the density detection sensor 100, a shutter 102 having an opening 102A corresponding to the arrangement position of the density detection sensor 100 is arranged.

  The shutter 102 can move to a position where the opening 102A is opposed to the density detection sensor 100 and a position where the density detection sensor 100 is shielded by reciprocating in a direction perpendicular to the longitudinal direction of the shutter unit. In FIG. 3, reference numeral 102 </ b> C denotes a spring, and the spring 102 </ b> C gives the shutter 102 a habit of moving the opening 102 </ b> A to a position where the density detection sensor 100 is shielded by a driving device described later.

  The shutter 102 is formed with racks 102B at both ends in the longitudinal direction in a direction perpendicular to the longitudinal direction, and the rack 102B meshes with a pinion gear 104 integrated with the rotating shaft of the mechanical clutch 103. The mechanical clutch 103 will be described later.

  The shutter 102 is rotationally driven by the driving device 105 described in FIGS. 4 and 5, so that the opening 102 </ b> A is moved to a position where the density detection sensor 100 is exposed to the outside and a position where the density detection sensor 100 is shielded. The case of moving 102A is selected.

FIG. 4 is a schematic diagram for explaining the configuration of the driving device 105.
In FIG. 4, the drive device 105 includes a single drive motor M and gear trains G and G ′ in which drive transmission paths from the drive motor M are set to 2 routes. On the input side, a motor gear G1 interlocked with the drive motor M is provided.

  The gear train is a fixing-side gear train indicated by a reference symbol G and a sensor-side gear train indicated by a reference symbol G ′. In the fixing-side gear train G, a first-stage gear G2 that meshes with the motor gear G1 is connected to an input-side gear. As an output side, a fixing gear 9G integrated with a fixing roller (not shown) of the fixing device is used as an output side, and a plurality of idle gears G3 and G6 are arranged therebetween.

  The sensor-side gear train G ′ includes a plurality of idle gears G3 and G4 between the first gear G2 ′ meshing with the motor gear G1 and the fixing gear 9G. In the vicinity of the step gear G2 ′, a sensor gear 103G is arranged that can switch the meshing state with the first step gear G2 ′ at a position that does not mesh with one of the idle gears indicated by reference numeral G3 ′.

  The sensor gear 103 </ b> G corresponds to the input side gear of the mechanical clutch 103 shown in FIG. 3, and is used as a gear that transmits power to the pinion gear 104.

  The output shaft of the drive motor M is provided with transmission switching means 106 (see FIG. 4) that can swing through the mechanical clutch 103.

  At the swing end of the transmission switching means 106, first-stage gears G2 and G2 'positioned on the input side of the gear train are supported at positions that do not engage with each other.

  The gear train is a fixing-side gear train indicated by a reference symbol G and a sensor-side gear train indicated by a reference symbol G ′. In the fixing-side gear train G, a first-stage gear G2 that meshes with the motor gear G1 is connected to the input gear. As an output side, a fixing gear 9G integrated with a fixing roller (not shown) of the fixing device is used as an output side, and a plurality of idle gears G3 and G6 are arranged therebetween.

  The sensor-side gear train G ′ is arranged at a position where it does not mesh with idle gears G3 ′, G4 that always mesh with the first gear G2 ′ that meshes with the motor gear G1, and with the idle gear G3 ′ that is located on the first gear side of the idle gear. A sensor gear 103G is provided.

  The sensor gear 103G corresponds to the input side of the mechanical clutch 103 shown in FIG. 3 and is used as a gear for transmitting power to the pinion gear 104.

  The output shaft M 1 of the drive motor M is provided with transmission switching means 106 that can swing through a mechanical clutch 103.

  At the swing end of the transmission switching means 106, first-stage gears G2 and G2 'positioned on the input side of the gear train are supported at positions that do not engage with each other.

  Although not shown in detail in the mechanical clutch 103, as shown in FIG. 5, the transmission switching means 106, which will be described later, is swung so that the first gear G2 and the idle gear G3 in the fixing gear train G are engaged. When rotating, the meshing is maintained by the bias of the spring 102C mounted on the shutter 103, and as shown in FIG. 4, the first-stage idle gear G3 ′ and the sensor gear 103G in the sensor-side gear train G ′ In the case where the first stage gear G2 'rotates in the direction of swinging so as to mesh with both of the gears, if the meshing is greater than the angle at which the meshing is started, the slipping causes slipping without further swinging. It has a function to be maintained.

  Therefore, as shown in FIG. 4, the transmission switching means 106 drives the drive motor in such a direction that it can mesh with both the first-stage gear G2 ′ of the sensor-side gear train G ′ and the first-stage idle gear indicated by reference numeral G3 ′. When the rotational force from M is transmitted and the meshing is started, the further oscillation is maintained without meshing with the slip.

  Further, when the transmission switching means 106 swings in the direction opposite to the above-described direction, as shown in FIG. 5, the first gear G1 and the idle gear G2 of the fixing gear train G are engaged, and the fixing gear 9G is rotated. The rotational force from the drive motor M is transmitted in the transmitted direction, and the meshing is maintained by the urging of the spring 102C provided in the shutter 102.

  The transmission switching means 106 swings so that the first gear G2 of the fixing gear train G meshes with the idle gear G3 located on the input side of the idle gear according to the driving direction corresponding to the rotational direction of the driving motor M. This state is the initial state, that is, the state during normal image formation. From this state, the first gear G2 ′ of the sensor side gear train G ′ is moved to the sensor gear 103G according to the drive direction of the drive motor M. It can be swung in the meshing direction.

  Therefore, the transmission switching means 106 maintains the state where the first gear G2 of the fixing side gear train G and the idle gear G3 are engaged with each other at the time of image formation and opens the opening 102A of the shutter 102 as shown in FIG. When exposing the density detection sensor 100, as shown in FIG. 4, a state is set in which the first gear G2 ′ of the sensor-side gear train G ′ meshes with the sensor gear 103G. For this reason, for each gear train G, G ′, the number of gears that makes the rotation direction of the fixing gear 9 </ b> G constant regardless of the rotation direction of the drive motor M is used.

  In the embodiment as described above, the driving force of the driving gear G is transmitted to the fixing gear 9G both during image formation and during density detection work. That is, in the fixing side gear train, the rotation of the first stage gear G2 is transmitted to the fixing gear 9G via the idle gears G3 and G6, and in the sensor side gear train G ′, the rotation of the first stage gear G2 ′ is this first gear. It is transmitted to the fixing gear 9G via idle gears G3 ', G4 and G6 which mesh with the first gear G2'.

  Power transmission to each gear train G, G ′ is performed by switching the rotation direction of the drive motor M. That is, when the rotation direction of the drive motor M at the time of image formation is normal rotation, as shown in FIG. 6A, the transmission switching means 106 is held at the initial position so as to set the drive path to the fixing side. Therefore, the rotation of the motor gear G1 is transmitted to each gear of the fixing side gear train G, and the fixing gear 9G rotates.

  On the other hand, when the density detection sensor 100 is operated, a density detection timing command is output from a control unit (not shown) on the image forming apparatus side. In this case, information such as after a predetermined number of prints is used for timing determination.

  In FIG. 6B, when it is determined that the density detection timing is behind, the drive motor M starts reverse rotation. When the drive motor M starts reverse rotation, the transmission switching means 106 mounted on the output shaft M1 swings to move the first stage gear G2 of the sensor side gear train G ′ to both the sensor gear 103G and the sensor gear 103G simultaneously. Engage. Thereby, the drive path to the sensor side is set (S12).

  When the first gear G2 ′ of the sensor-side gear train G ′ meshes with the sensor gear 103G, the rotation of the sensor gear 103G is transmitted to the pinion gear 104, causing the shutter 102 to move forward, and the opening 102A is removed from the position of the density detection sensor 100. Thus, the density detection sensor 100 is exposed to the outside (S13).

  When the density acquisition detection is completed, the drive motor M returns to the rotation direction during normal image formation. When the drive motor M returns to the initial rotation direction, a drive path as shown in FIG. 4 is set, and the fixing gear 9G is kept rotating. In this case, the drive motor M rotates the fixing gear 9G in a predetermined direction. At this time, the transmission switching member 106 is moved in the fixing-side gear train G by the bias of the spring 102C provided in the shutter 102. The gear is kept in meshing. Note that the return state of the shutter 102 to the initial position is determined by using a correspondence state between a detection member such as a limit sensor indicated by symbol ST in FIG. 3 and a detection unit provided on the shutter 102 side.

  Next, a modification of the main part of the shutter 102 will be described.

  As shown in FIG. 7, a brush member BR that can clean the surface of the density detection sensor using the reciprocation of the shutter 102 is provided on the surface of the shutter 102 that faces the density detection sensor 100. Accordingly, the density detection sensor 100 can be cleaned only by using the existing shutter 102 without requiring a special cleaning member driving mechanism.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 9 Fixing apparatus 9G Fixing gear 100 Density detection sensor 102 Shutter 102A Opening 103 Mechanical clutch 103G Sensor gear 104 Shutter side pinion gear 105 Drive apparatus 106 Transmission switching means G, G 'Gear train

JP 2006-91904 A JP 2004-138976 A Japanese Unexamined Patent Publication No. 2009-8816

Claims (7)

In a driving device in which different power transmission paths are set for a single drive source and a driven member is provided at an output position of the power transmission path,
One of the power transmission paths always has a member that moves in the same direction, and the other one of the power transmission paths has a member that moves in opposite directions according to forward and reverse driving of the drive source. Each of which is configured to transmit power in a direction in which a member located in one of the power transmission paths is moved in the same direction regardless of whether the drive source is forward or reverse driven. The drive device characterized.   The power transmission path is provided with a gear train having a plurality of gears, and a transmission for transmitting a driving force to one of the gear trains on the input side of the gear train according to the drive direction of the drive source. 2. The driving apparatus according to claim 1, further comprising a switching unit.   The gear train provided in one of the power transmission paths is combined with a number of gears that allow movement in the same direction regardless of the drive direction of the drive source. The drive device according to claim 1 or 2.   The transmission switching means includes a rocking member that can be interlocked with the drive source, and a gear on the drive source side is arranged on the rocking end side of the rocking member by a rocking direction according to the driving direction of the drive source. An input gear that can be switched to a meshing state is provided, and the input gear meshes with the gear on the drive source side to transmit power to one of the gear trains. The drive device described.   The gear in the last stage of the gear train is allowed to rotate only a predetermined amount in one of the driving directions of the drive source, and maintains a rotation stop state when rotating in the direction opposite to the one direction. The drive device according to claim 4, wherein an operating gear provided in the clutch is engaged. An image forming apparatus comprising the driving device according to claim 1.
One of the power transmission paths is provided with a fixing device having a gear that meshes with the last stage gear of the gear train, and the other of the power transmission paths has a gear positioned at the last stage of the gear train. A shutter is provided that has a working gear that is allowed to rotate in a predetermined amount in one direction by being engaged and stopped in a direction opposite to the one direction, and that can be reciprocated by selecting the rotating direction of the working gear, An image forming apparatus, wherein members provided in the fixing device are driven in the same direction regardless of a driving direction of the driving source.   The image forming apparatus according to claim 6, wherein the shutter is a member capable of reciprocating between a position where the density detection sensor is exposed to the outside and a position where the density detection sensor is covered.

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