JP4405789B2 - Forward / reverse clutch mechanism using swing gear, and image forming apparatus using this clutch mechanism - Google Patents

Description

  The present invention relates to a forward / reverse clutch mechanism using a swing gear and an image forming apparatus using the clutch mechanism.

  For convenience, an electrophotographic full-color image forming apparatus in which a plurality of image forming units of different colors are arranged in parallel and an intermediate transfer member that moves through each image forming unit is arranged will be described as an example.

  When outputting a full-color image (in full-color image formation mode), the image forming apparatus converts each color toner image formed as a component color image of a full-color image on the surface of the photosensitive drum, which is an image carrier of each image forming unit. A full-color toner image is synthesized and formed by sequentially superimposing and transferring by a primary transfer means on the surface of the intermediate transfer member that moves through the forming portion. Then, the full-color toner image synthesized and formed on the surface of the intermediate transfer member is secondarily transferred to a recording material such as paper or plastic sheet by a secondary transfer unit, and then thermally fused, mixed, and fixed by a thermal fixing unit. To output a full-color image formed product. When a monochrome image is output (in the monochrome image formation mode), only the image forming unit that forms a black toner image among the plurality of image forming units having different colors is operated to perform photosensitivity of the image forming unit. The black toner image formed on the drum surface is primarily transferred onto the surface of the intermediate transfer member, and then secondary transferred from the surface of the intermediate transfer member to the recording medium at the secondary transfer portion, and is thermally melted and fixed by the heat fixing means. To output a monochrome image formed product.

When outputting a monochrome image, the black toner image is used for the purpose of preventing deterioration due to contact between the photosensitive drum of the image forming unit other than the black toner image image forming unit and the intermediate transfer member, which is not involved in image formation. An intermediate transfer member avoiding mechanism is employed in which the intermediate transfer member is not brought into contact with the photosensitive drum of the color toner image forming unit other than the forming unit (see, for example, Patent Document 1).
Japanese Patent Laid-Open No. 9-292753

  An object of the present invention is, for example, as a forward / reverse clutch mechanism used in a drive transmission portion of an intermediate transfer member avoidance mechanism as described above in an image forming apparatus using an electrophotographic method such as a computer printer or a copying machine. An object of the present invention is to realize a forward / reverse clutch mechanism capable of disconnecting power transmission at a predetermined phase according to the drive time and rotation direction of a motor, using only a mechanical configuration without using electric parts such as sensors and electromagnetic clutches.

  The present invention is a forward / reverse clutch mechanism using a swing gear characterized by the following configuration, and an image forming apparatus using the clutch mechanism.

[1]:
1) An input gear that rotates forward and backward,
2) is rotatably held between the first phase and a second phase, in the in the first phase and the second phase, not meshed with the input gear, the first phase and the second phase other than the phase Is engaged with a tooth group arranged to mesh with the input gear, a first swing gear and a second swing gear having a boss in the center, and the first swing gear and the second swing gear, respectively. a first protrusion and a second protrusion which, a first guide hole and second guide hole for guiding the boss of the first swing gear and the second swing gear, an output gear unit consisting of,
Have
The first guide hole and the second guide hole are formed so that the first swing gear and the second swing gear are engaged with the first protrusion and the second protrusion, respectively. While moving to a state away from the one protrusion and the second protrusion, the distance between the center of the first swing gear and the second swing gear and the center of the input gear is kept constant. An arc shape for guiding the gear and the second swing gear;
In the first phase, when the input gear rotates forward, the first swing gear on the output gear unit moves away from the first protrusion, and when the input gear rotates reversely, the first gear on the output gear unit. The input gear continues to engage with the first swing gear until a phase where the swing gear engages with the first protrusion and at least the teeth of the output gear unit engage with the input gear;
In the second phase, when the input gear reverses, the second swing gear on the output gear unit moves away from the second protrusion, and when the input gear rotates forward, the second gear on the output gear unit. The rocking gear is engaged with the second protrusion, and the input gear continues to be engaged with the second rocking gear until at least the phase where the teeth of the output gear unit are engaged with the input gear. A forward / reverse clutch mechanism.

[2]: the output gear unit, the first phase and biased to remain in the second phase, the forward reverse clutch mechanism according to [1], characterized in that a biasing means for positioning .

[3] : The toner image formed and supported on the image carrier of the image forming unit is primarily transferred onto the intermediate transfer member, and the toner image on the intermediate transfer member is secondarily transferred to the recording medium to form an image. In the image forming apparatus to be executed,
An intermediate transfer body moving mechanism including a forward / reverse rotation clutch mechanism for moving the intermediate transfer body toward and away from the image carrier of the image forming unit, wherein the forward / reverse rotation clutch mechanism is [1] or [2 image forming apparatus, characterized in that the forward reverse clutch mechanism according to.

[4] The image forming apparatus according to [3] , wherein the image forming apparatus includes a plurality of image forming portions of different colors, and a plurality of toner images are superimposed on the intermediate transfer member and primarily transferred.

  FIG. 1 is a schematic configuration diagram of an image forming apparatus in which a forward / reverse clutch mechanism using a swing gear according to the present invention is incorporated in a swing mechanism of a primary transfer roller unit.

  The image forming apparatus of this example is a tandem-type electrophotographic full-color printer that combines a plurality of photosensitive drums that are image carriers, and is an intermediate transfer belt type monochrome / electrophotographic full-color printer.

  Y, M, C, and K are first to fourth image forming units that form toner images of yellow, magenta, cyan, and black, respectively, and are arranged in parallel from the bottom to the top.

  These first to fourth image forming units Y, M, C, and K have the same configuration and electrophotographic image forming function except that the colors of the toner images to be formed are different as described above. Yes. That is, each of the first to fourth image forming units includes a drum-type electrophotographic photosensitive member (photosensitive drum) 2 as an image carrier, a charging roller 3 as a primary charging unit, and a laser irradiation device 4 as an exposure unit. And a toner developing device 5 as a developing means, a transfer roller 6 as a primary transfer means, a photosensitive drum cleaner 7 and the like. The developers accommodated in the toner developing devices 5 of the first to fourth image forming units are yellow toner, cyan toner, magenta toner, and black toner, respectively.

  Reference numeral 8 denotes an endless belt-shaped intermediate transfer belt as an intermediate transfer member. The four image forming units Y, M, C, and K of the four image forming units are arranged on the photosensitive drum 2 side. Over the entire portion, the plurality of support rollers 9, 10, 11 are suspended and arranged in the vertical direction. In each of the first to fourth image forming units, the primary transfer roller 6 is brought into pressure contact with the photosensitive drum 2 via the intermediate transfer belt 8. A contact portion between each photosensitive drum 2 and the intermediate transfer belt 8 is a primary transfer portion.

At the time of full-color image output, the photosensitive drums 2 of the first to fourth image forming units Y, M, C, and K are rotationally driven counterclockwise as indicated by arrows, and a charging roller to which a charging bias is applied during the rotation process. 3 is subjected to primary charging processing uniformly to a predetermined polarity and potential, and each of the charging processing surface is processed by a laser scanner device 4 as a color separation component image of each of yellow, magenta, cyan and black. Optical image exposure LY, LM, LC, and LK is performed according to the image pattern, and an electrostatic latent image of image information is formed on each photosensitive drum 2. Each of the electrostatic latent images is developed as a toner image by the developing device 5, whereby an electrophotographic process is performed on each of the surfaces of the photosensitive drums 2 of the first to fourth image forming units Y, M, C, and K. As a result, yellow, magenta, cyan, and black color toner images, which are color separation component images of the full-color image, are formed at a predetermined sequence control timing.

  In each of the first to fourth image forming units Y, M, C, and K, yellow, magenta, cyan, and black color toner images formed on the surface of each photosensitive drum 2 are rotated by each photosensitive drum 2. The first to fourth image forming units Y, M, C, and K are rotated with respect to the surface of the intermediate transfer belt 8 that is rotationally driven at substantially the same speed as the photosensitive drum 2 in the clockwise direction indicated by the forward arrow. The images are sequentially superimposed and transferred by a primary transfer bias applied to the primary transfer roller 6 in the primary transfer portion. As a result, an unfixed full-color toner image (mirror image) is synthesized and formed on the surface of the intermediate transfer belt 8 that is rotationally driven. In each of the first to fourth image forming portions Y, M, C, and K, residual toner on the photosensitive drum 2 after the primary transfer of the toner image to the surface of the intermediate transfer belt 8 is transferred to the surface of the photosensitive drum 2 by the cleaning device 7. Removed from.

  Reference numeral 12 denotes a secondary transfer roller. The roller 10 of the plurality of rollers 9 to 11 that suspends the intermediate transfer belt 8 is used as an opposing roller, and the intermediate transfer belt 8 is interposed between the rollers 10. The intermediate transfer belt 8 is interposed between the outer surfaces of the intermediate transfer belt 8. A contact portion between the secondary transfer roller 12 and the intermediate transfer belt 8 is a secondary transfer portion.

  Reference numeral 13 denotes a paper feed cassette disposed in the lower part of the printer main body, in which a transfer material P as a recording medium is stacked and accommodated. The pickup roller 14 is driven at a predetermined sequence control timing, and the transfer material P in the paper feed cassette 13 is separated and fed, and passes through the sheet path 17 including the conveying roller 15 and the registration roller 16 at a predetermined timing. Is fed to the secondary transfer section. Unfixed full-color toner images on the intermediate transfer belt 8 are collectively transferred onto the surface of the transfer material P by the transfer bias applied to the secondary transfer roller 12 in the secondary transfer portion. Transfer residual toner remaining on the intermediate transfer belt 8 is removed by a cleaning device 18.

  The transfer material P that has passed through the secondary transfer portion is separated from the surface of the intermediate transfer belt 8 and sent to the fixing device 20 by the conveying belt 19. The unfixed full-color toner image on the transfer material P is heated by the fixing device 20. Then, the pressure is applied to the transfer material P so that it is melted, mixed and fixed, and is discharged as a color image formed product through a sheet path 21 onto a discharge tray 22 disposed on the upper surface of the printer main body.

  At the time of monochrome image output, only the uppermost fourth image forming unit K, which is an image forming unit that forms a black toner image among the first to fourth image forming units Y, M, C, and K described above. Is formed, the black toner image formed on the surface of the photosensitive drum 2 of the image forming unit K is primarily transferred onto the surface of the intermediate transfer belt 8, and the surface of the intermediate transfer belt 8 is further transferred at the secondary transfer unit. To the transfer material P, the image is fixed by the fixing device 20 and output as a monochrome image formed product.

  Reference numeral 100 denotes an intermediate transfer member avoiding mechanism. 2 and 3 are enlarged views of the intermediate transfer member avoiding mechanism portion 100. FIG. 2 shows a state when a full-color image is output, and FIG. 3 shows a state when a monochrome image is output.

  Reference numeral 31 denotes a fixed frame, and a plurality of rollers 9 to 11 with the intermediate transfer belt 8 suspended and stretched on the frame 31 are rotatably arranged. Reference numeral 32 denotes a primary transfer roller unit, which is supported by the fixed frame 31 so as to freely swing in the directions of arrows A and B around the boss 32a on the upper end side of the unit. The primary transfer roller unit 32 includes three primary transfer rollers for the photosensitive drums 2 of the first to third image forming units Y, M, and C that respectively form a yellow toner image, a magenta toner image, and a cyan toner image. 5 is rotatably arranged. Only the primary transfer roller 5 with respect to the photosensitive drum 2 of the fourth image forming unit K is rotatably disposed on the fixed frame 31, and the intermediate transfer belt 8 is sandwiched between the photosensitive drum 2 of the image forming unit K and a predetermined value. The primary transfer portion is always formed in pressure contact with the substrate.

  The swing mechanism 33 includes an output gear unit (a forward / reverse clutch mechanism using a swing gear) 1, a motor 34, a cam 35, and an input gear 36. As shown in FIG. 6, the output gear unit 1 includes a tooth group 1a, a first swing gear 1b, a second swing gear 1c, a first protrusion 1d, a second protrusion 1e, a first guide hole 1f, and a second guide hole. 1g.

  The primary transfer roller unit 32 is controlled so that the cam 35 of the swing mechanism 33 is switched to the first phase rotation angle state shown in FIGS. The primary transfer roller unit 32 is pressurized by the cam 35 controlled to be switched to the rotation angle state of the first phase, and is approaching the first to third image forming portions Y, M, and C around the boss 32a. The three primary transfer rollers 5 disposed in the primary transfer roller unit 32 while oscillating against the tension of the intermediate transfer belt 8 in the direction are photosensitive of the first to third image forming portions Y, M, and C, respectively. The intermediate transfer belt 8 is pressed against the body drum 2 with a predetermined pressure so as to form a primary transfer portion.

  The primary transfer roller unit 32 is controlled to switch the cam 35 of the swing mechanism 33 to the rotation angle state of the second phase in FIGS. 3 and 5 when outputting a monochrome image. The pressure of the primary transfer roller unit 32 is released by the cam 35 that is controlled to be switched to the rotation angle state of the second phase, and the primary transfer roller unit 32 is first to first centered on the boss 32 a by the tension of the intermediate transfer belt 8. The three primary transfer rollers 5 disposed in the primary transfer roller unit 32 by swinging in the B direction away from the three image forming units Y, M, and C are respectively provided in the first to third image forming units Y and M. The intermediate transfer belt 8 is held in a non-contact state from the photosensitive drums 2 of the first to third image forming units Y, M, and C apart from the C photosensitive drum 2. Only the primary transfer roller 5 of the fourth image forming unit K, which is an image forming unit for forming a black toner image, is pressed against the photosensitive drum 2 of the image forming unit K with the intermediate transfer belt 8 therebetween. The primary transfer portion is maintained.

  The cam 35 is connected to the output gear unit 1 through a shaft 35a. The output gear unit 1 is arranged so that the tooth group 1a meshes with an input gear 36 connected to the motor 34, and the input gear 36 rotates forward in the direction D in the figure and driven in the direction E in the figure by driving the motor 34. Therefore, the output gear unit 1 also rotates forward in the direction D in the figure and reversely in the direction E in the figure, and the cam 35 rotates accordingly. The output gear unit 1 is provided with a tooth group 1a that does not mesh with the tooth group 1a and the input gear 36 in the first phase and the second phase but meshes with the input gear 36 in phases other than the first phase and the second phase. . The first oscillating gear 1b and the second oscillating gear 1c have bosses, which are rotatably attached to the first guide hole 1f and the second guide hole 1g, respectively. 1b and the input gear 36 are arranged so that the second oscillating gear 1c and the input gear 36 are engaged in the second phase.

  The first protrusion 1d is the first protrusion 1d when the input gear 36 rotates forward so that the output gear unit 1 engages with the first swing gear 1b when the input gear 36 reverses in the first phase. The second protrusion 1e is arranged so that the one oscillating gear 1b is separated, and the output gear unit 1 is engaged with the second oscillating gear 1c when the input gear 36 is rotated forward in the second phase. In addition, when the input gear 36 rotates in the reverse direction, the second oscillating gear 1c is arranged to be separated.

  Further, the first guide hole 1f and the second guide hole 1g are distances between the centers of the first swing gear 1b and the second swing gear 1c and the center of the input gear 36 in the first phase and the second phase, respectively. Is formed in a circular arc shape so that the first oscillating gear 1b and the second oscillating gear 1c are engaged with the first protrusion 1d and the second protrusion 1e, respectively, by forward and reverse rotation of the input gear 36. The first oscillating gear 1b and the second oscillating gear 1c are guided so that they can move from the separated state to the separated state or vice versa.

When the full color image is output, the motor 34 is driven forward so that the input gear 36 and the output gear unit 1 are rotated forward in the direction D in the figure, and the output gear unit 1 reaches the first phase. Since only the moving gear 1b meshes with the input gear 36 and the first swing gear 1b rotates idly, the power transmission to the output gear unit 1 is cut (FIG. 6). Accordingly, the cam 35 comes into contact with the transfer roller unit 32 in the first phase, and the transfer roller unit 32 is held in the state shown in FIGS.

When switching from this state to monochrome image output, the motor 34 is driven in reverse , so the input gear 36 is rotated in the direction E in the figure. In the output gear unit 1, first, the first oscillating gear 1 b meshes with the input gear 36 and rotates, and the first oscillating gear 1 b engages with the first protrusion 1 d, so that power is transmitted to the output gear unit 1. (FIG. 7) Then, since the tooth group 1a meshes with the input gear 36, the output gear unit 1 reverses in the direction E shown in the figure. When the output gear unit 1 reaches the second phase, only the second oscillating gear 1c meshes with the input gear 36, and the second oscillating gear 1c rotates idly, so that power transmission to the output gear unit 1 is cut off. (FIG. 8). Accordingly, the cam 35 comes into contact with the transfer roller unit 32 in the second phase, the contact between the first transfer roller 4a other than the monochrome transfer roller 4a and the corresponding image carrier 2a is released, and the transfer roller unit 32 is shown in FIG. -It is hold | maintained in the state of FIG.

  Here, as shown in FIG. 10, the first abutting member that abuts in the direction in which the output gear unit 1 rotates forward in the first phase so that the output gear unit 1 stays in the first phase and the second phase, respectively. 1h and in the second phase, the second abutting member 1J that abuts in the reverse direction of the output gear unit 1 and the output gear unit are urged so as to abut against the first abutting member 1h and the second abutting member 1J For example, if an urging means 1k such as a tension coil spring is provided, the tooth surfaces of the tooth group 1a on the output gear unit 1 and the input gear 36, which are generated by the influence of the weight of the output gear unit 1, Noise and wear due to intermittent contact can be suppressed.

  The forward / reverse clutch mechanism using the swing gear of the present invention is not limited to the clutch means of the primary transfer roller unit swing mechanism of the image forming apparatus shown in the above embodiment, and is widely used in the drive transmission unit. It is effective to use as.

  In other words, a forward / reverse clutch mechanism capable of disconnecting the drive transmission at a predetermined phase according to the drive time and rotation direction of the motor is realized by using only the mechanical configuration without using electric parts such as sensors and electromagnetic clutches, thereby simplifying the configuration and reducing the cost. You can go down.

1 is a schematic configuration diagram of an example of an image forming apparatus in Embodiment 1. FIG. FIG. 4 is an enlarged view of an intermediate transfer member avoiding mechanism portion at the time of outputting a full color image. FIG. 6 is an enlarged view of an intermediate transfer member avoiding mechanism portion at the time of outputting a monochrome image. FIG. 4 is an enlarged view of a primary transfer roller unit portion (a cross-sectional view showing a phase (first phase) of an output gear unit and a cam) when a full-color image is output. FIG. 4 is an enlarged view of a primary transfer roller unit portion (a cross-sectional view showing a phase (second phase) between an output gear unit and a cam) when a monochrome image is output. It is a front view of an output gear unit (at the time of a 1st phase and normal rotation). It is a front view of an output gear unit (at the time of 1st phase and reverse rotation). It is a front view of an output gear unit (at the time of 2nd phase and reverse rotation). It is a front view of an output gear unit (at the time of 2nd phase and normal rotation). It is a front view of an output gear unit (with an urging means).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Output gear unit 1a ... Tooth group 1b ... 1st swing gear 1c ... 2nd swing gear 1d ... 1st protrusion 1e ... 2nd protrusion 1f ... 1st guide hole 1g ... 1st Two guide holes 1h ··· First abutting member 1J ··· Second abutting member 1k ··· Energizing means Y, M · C · K · · · First to fourth image forming portions 2 · · · Image carrier ( Photosensitive drum)
6 ... 1st transfer roller 8 ... Intermediate transfer body (intermediate transfer belt)
12 ... Second transfer roller 31 ... Fixed frame 32 ... Transfer roller unit 32a ... Boss 34 ... Motor 35 ... Cam 35a ... Shaft 36 ... Input gear

Claims (4)

1) An input gear that rotates forward and backward,
2) is rotatably held between the first phase and a second phase, in the in the first phase and the second phase, not meshed with the input gear, the first phase and the second phase other than the phase Is engaged with a tooth group arranged to mesh with the input gear, a first swing gear and a second swing gear having a boss in the center, and the first swing gear and the second swing gear, respectively. a first protrusion and a second protrusion which, a first guide hole and second guide hole for guiding the boss of the first swing gear and the second swing gear, an output gear unit consisting of,
Have
The first guide hole and the second guide hole are formed so that the first swing gear and the second swing gear are engaged with the first protrusion and the second protrusion, respectively. While moving to a state away from the one protrusion and the second protrusion, the distance between the center of the first swing gear and the second swing gear and the center of the input gear is kept constant. An arc shape for guiding the gear and the second swing gear;
In the first phase, when the input gear rotates forward, the first swing gear on the output gear unit moves away from the first protrusion, and when the input gear rotates reversely, the first gear on the output gear unit. The input gear continues to engage with the first swing gear until a phase where the swing gear engages with the first protrusion and at least the teeth of the output gear unit engage with the input gear;
In the second phase, when the input gear reverses, the second swing gear on the output gear unit moves away from the second protrusion, and when the input gear rotates forward, the second gear on the output gear unit. The rocking gear is engaged with the second protrusion, and the input gear continues to be engaged with the second rocking gear until at least the phase where the teeth of the output gear unit are engaged with the input gear. A forward / reverse clutch mechanism. It said output gear unit, the first phase and biased to remain in the second phase, the forward reverse clutch mechanism according to claim 1, characterized in that a biasing means for positioning. Image formation in which the toner image formed and supported on the image carrier of the image forming unit is primarily transferred onto the intermediate transfer member, and the toner image on the intermediate transfer member is secondarily transferred to the recording medium and image formation is performed. In the device
3. An intermediate transfer member moving mechanism including a forward / reverse rotation clutch mechanism for moving the intermediate transfer member toward and away from the image carrier of the image forming unit, wherein the forward / reverse clutch mechanism is defined in claim 1 or 2 . An image forming apparatus comprising the forward-reverse clutch mechanism described above. 4. The image forming apparatus according to claim 3 , further comprising a plurality of image forming portions of different colors, wherein a plurality of toner images are superposed on the intermediate transfer member and primarily transferred.