JPH01199023A - Drive transmission device - Google Patents

Abstract

PURPOSE:To absorb vibration due to displacement in an axis between couplings, by a method wherein a resilient body is secured to the protrusion of at least the one of couplings having protrusions engaged with each other. CONSTITUTION:Couplings 451 and 454 are provided on opposing surfaces with projections 455 and 456 engageable with each other, and the protrusion 456 of at least the one coupling 454 is secured to a resilient body 457. The resilient body 457 is molded in an annular state by using, for example, urethane having excellent compression and restoration property, and is preferably engaged with the protrusion 456. This constitution absorbs vibration due to displacement in an axis between the couplings, resulting in prevention of the generation of noise and production of unevenness in a stage due to vibration.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a drive transmission device that connects an image forming apparatus main body and drive shafts provided in respective developing units that are removably provided in the main body. be.

[Conventional technology]

Generally, an electrophotographic image forming apparatus includes a photoreceptor drum at its center and a charger and a developer around the photoreceptor drum. This developing device is used to develop the electrostatic latent image formed on the photoreceptor drum into a toner image. It needs to be kept constant. That is, if this distance changes, the electric field changes, which adversely affects developability. For this purpose, an abutting roller with a slightly larger diameter is rotatably attached to the shaft of the developing sleeve, and the developing device is pushed toward the photoreceptor drum by a spring or the like so that the roller abuts against the surface of the photoreceptor drum. Forced.

Further, the developing device can be pulled out in the axial direction of the photoreceptor 1 ram for toner replenishment or maintenance, inspection and repair, and when the developing device is stored, the developing sleeve is installed at the end of its rotating shaft. The coupling is coupled to a coupling fixed to the end of a drive shaft that is rotatably supported on the main body side, so that it can receive drive from the main body side.

[Problem that the invention seeks to solve]

However, since the developing device is provided with some play in order to improve its ease of pulling out, the axes of the couplings do not always align perfectly when the developing device is housed in a predetermined position. Therefore, in the past, smooth rotation of the developing sleeve could not be obtained. In particular, image forming apparatuses that can form color images, for example, charge the surface of a photoreceptor drum with a charger at its one-turn opening, form a latent image corresponding to a first color (for example, red), and store red toner. Develop it in a developing device, lightly charge it twice, and create a second color (for example, blue).
A latent image corresponding to the color is formed and developed in a developing device containing blue toner, and then lightly charged three times to create a third color (
For example, in an image forming apparatus equipped with a plurality of developing devices, in which a latent image corresponding to black (black) is formed and developed overlappingly using a developing device containing black toner, a cleaning blade overlaps a toner image on the surface of a photoreceptor drum. As the photoconductor drum slides into contact with and separates from the drive, the load on the photoreceptor drum fluctuates, causing the axis to shift, and each time the developing unit, which is in contact with the drum surface via a roller, also moves, causing the fixed drive source to move. The drive transmission system was extremely unstable, with the drive transmission being out of alignment and abnormal sounds and vibrations impairing the registration performance of overlapping images.

This invention is intended to solve the above problems, and is capable of stable drive transmission even when the developing unit moves, absorbs vibrations caused by misalignment between the couplings, and eliminates unevenness caused by abnormal noise and vibration. It is an object of the present invention to provide a drive transmission device that does not cause such problems.

[Means for solving problems]

To achieve the above object, the present invention provides a drive transmission device including couplings having protrusions on opposing surfaces at each end of opposing rotating shafts that can be engaged with each other. An elastic body is fixed to the photoreceptor drum, so that even if load fluctuations occur due to the sliding contact and separation of the cleaning blade from the photoreceptor drum, this effect will not appear on the image.

〔Example〕

Next, the present invention will be explained based on drawings of an image forming apparatus capable of forming color images.

In FIG. 1, A is a document reading section, and B is a part of the printer. The document reading section A illuminates a document 2 placed on a platen glass 1 provided on the top surface of the housing with a fluorescent lamp 5 provided on a carriage 4 moving on a slide rail 3, and passes the reflected light through a slit 6. The lens can be taken out by the first mirror 7 through the lens, and can be led out to the lens reading unit 20 via the V mirrors 9 and 9' provided in the movable mirror unit 8.

The carriage 3 and the movable mirror unit 8 are driven by pulleys 11.12, 13.14 connected to a stepping motor 10 via a wire 15. In this case, the movable mirror unit 8 moves on the slide rail 3 at 1/2 the speed of the carriage 4 in the same direction. Reference numerals 16 and 17 denote standard white plates provided on the lower surface of both ends of the platen glass 1, and the standard white plates 16 and 17 are used to obtain standard white signals before and after the start and end of document reading scanning.

The lens reading unit 20 has a lens 2 as shown in the second figure.
1. Prism 22, first reading board 24, red channel (hereinafter referred to as R-ch) CCD 25, second reading board 2
6. Cyan channel (hereinafter referred to as C-ch) CCD2
It consists of 7. The original light image transmitted by the first mirror 7 and the (1) mirror 9.9' is focused by the lens 21, and converted into an R-ch image and a C-ch image by the guichroic mirror 23 built in the prism 22. R-ch CCD 25 separated into two and provided on the first reading board 24,
An image is formed on each light receiving surface of the C-ch CCD 27 provided on the second reading board 26. This R-chCCD2
The image signals output from the C-ch CCD 27 and the C-ch CCD 27 are processed in a signal processing section 28, and color-separated color signals corresponding to the toner colors are output to a writing unit 29 provided in the printer B.

As shown in the third diagram, the writing unit 29 includes a semiconductor laser 31, a polygon mirror 32 that is rotated by a drive motor 30 to rotate and scan the laser beam generated by the semiconductor laser 31, an rθ lens 33, and cylindrical lenses 35, 36. It is equipped with The laser beam generated by the semiconductor laser 31 passes through the cylindrical lens 35 and is rotated and scanned by the polygon mirror 32, passes through the fθ lens 33, the cylindrical lens 36, and the reflecting mirror 37, and is projected onto the surface of the photoreceptor drum 40. form. Reference numeral 34 denotes an index sensor that detects the start of beam scanning, and detects the start of scanning by the laser beam via a reflecting mirror 38.

When the index sensor 34 detects the start of scanning, the first color signal output from the signal processing section 28 is input to the writing unit 29, and modulation of the beam by the color signal is started. The modulated beam is applied to the photosensitive drum 4 which is uniformly charged in advance by a charger 41.
Scan over 0. Main scanning by this beam and the drum 40
A latent image corresponding to the first color is formed on the drum surface by the sub-scanning caused by the rotation of the drum, and the latent image is developed by a developing device 43 loaded with, for example, red toner. After this red toner image is formed, the drum surface is charged again by the charger 41 in the next copy cycle. In this case, the cleaning blade 47 of the cleaning device 46 is separated from the photosensitive drum 40 to prevent the red toner image from being scraped off.

Next, the second color signal output from the signal processing section 28 is input to the writing unit 29, and the second color signal is input to the writing unit 29.
A latent image corresponding to the second color is formed on the surface of the tank. The latent image is then developed by a developing device 44 loaded with, for example, blue toner. That is, the blue toner image is formed on top of the already formed red toner image.

Next, based on the control signal generated by the signal processing section 28, a black toner image is formed on the surface of the photosensitive drum 40 by the developing device 45 loaded with black toner by the same operation as described above.

As shown in FIG. 4, the developing units 44 to 45 include a developing sleeve 441 in which a magnet is embedded in the outer periphery, a main stirring member 443 for the developer 442, and a developer 442 that moves the developer in one direction from one end side to the other end side in the developing width direction. The developer is provided with a first conveying means 444 for conveying the developer, and a second conveying means 445 for conveying the developer in the opposite direction to the second conveying means 444. An alternating current and a direct current bias are applied to the developing sleeve 441, and a jumping phenomenon is performed by the toner of the two-component developer, so that development is performed without contacting the grounded photoreceptor drum 40.

Reference numeral 446 denotes a doctor blade that adheres the developer in the form of a thin film to the surface of the developing sleeve 441, and 447 denotes a developer that adheres to the developing sleeve and is carried to the front of the photoreceptor drum 40, where the toner content has been reduced by being used for development. This is a scraper for scraping off (mainly carrier) from the surface of the developing sleeve 441. The tired developer scraped off by the scraper 447 is well stirred and mixed while being circulated by the first conveying means 444 and the second conveying means 445 around both ends of the partition wall 448 as shown by the arrow, and is reactivated. turned into
It is attached to the developing sleeve 441 by the main stirring member 443 .

In order to keep the distance between the developing sleeve 441 and the photoreceptor drum 40 constant, the developing units 44 to 45 are arranged in a fifth position.
As shown in FIG. is biased toward the photoreceptor drum by a biasing means 449 such as a spring.

Further, the developing units 43 to 45 can be pulled out in the axial direction (in the direction of the arrow) of the photosensitive drum 40 for toner replenishment or maintenance, inspection and repair. When the developing device is stored, the developing sleeve 441 is attached to its shaft 4 as shown in FIGS. 4 and 7.
A coupling 451 fixed to the shaft end of a shaft 41' is connected to a coupling 454 fixed to the shaft end of a shaft 453' which is connected to a drive motor 452 provided on the main body side via a gear train 453. drive transmission.

The couplings 451, 454 have protrusions 455, 456 on opposing surfaces that can engage with each other, and the protrusions 456 of at least one of the couplings 454 (in the embodiment, on the main body side) are provided with an elastic body as shown in the sixth figure. 457 is fixed. That is, when the drive of the developing sleeve of the developing device that is abutted against the photosensitive drum 40 via the abutment rollers 450 is transmitted by engagement between the protrusions provided on the opposing surfaces of the coupling, the axial center is misaligned. However, as mentioned above, if the protrusion of at least one of the couplings has an elastic body 4
57 is fixed, it absorbs vibrations caused by misalignment of the axis. Therefore, it is preferable that the elastic body 457 is formed into a ring shape using, for example, urethane rubber with good compression and recovery properties, and this is fitted onto the projection 456. Of course, the elastic body may be used for the above purpose. For example, it may have a shape other than this, the protrusion itself may be made of a spring material other than urethane rubber, or the coupling itself may be made of a suitable elastic material.

The three-color toner images developed as described above are separated one by one by the paper feed belt 52 of the paper feed unit 50 in the transfer unit 51, and are timed by the paper feed roller 53 and placed on the guide plate 5.
The images are transferred all at once onto the recording paper 55 that has been sent through the process.

After that, the recording paper is transferred to the photosensitive drum 4 by the separation electrode 56.
0, placed on a conveyor belt 57, and transferred to a fixing device 5.
8, and is fixed by heat and pressure with fixing rollers 58a and 58b, and then transferred to output roller 5 as a color hard copy.
It is held between 9a and 59b and discharged outside the machine.

After the transfer is completed, unnecessary toner remaining on the photosensitive drum 40 is scraped off by bringing the blade 47 of the cleaning device 46 into contact with it. A cleaning roller 4B provided on the downstream side of the cleaning device 46 completely removes the small amount of toner left behind between the drum surface and the blade when the blade 47 separates from the drum 40 for the next exposure and development after cleaning. It is used for removal and rotates in the opposite direction to the drum.

In the above embodiment, when forming a color image, first, during the first rotation of the photosensitive drum 40, the surface of the photosensitive drum 40 is charged with a charger, a latent image corresponding to red is formed, and a developing device containing red toner is used. Develop at 43. During the second rotation, the toner is charged again to form a latent image corresponding to blue, which is superimposed and developed in a developing device 44 containing blue toner. During the third rotation, the toner is charged again to form a latent image corresponding to black, which is superimposed and developed in a developing device 45 containing black toner. In this case, the cleaning blade 47, which was in sliding contact with the drum surface at the beginning of one rotation of the photosensitive drum 40, separates from the drum surface in the latter half, the second rotation is performed while remaining separated, and the third rotation comes into sliding contact from the latter half. When load fluctuations occur on the photoreceptor drum 40, the axial center of the photoreceptor drum 40 shifts, and each time, the developing device that abuts the drum surface via a roller moves, and even if the coupling becomes misaligned, the protrusion of the coupling will shift. They engage with each other through an elastic body, absorbing misalignment and vibration, and preventing the negative effects of abnormal noise and vibration.

〔Effect of the invention〕

As described above, the present invention provides a drive transmission device including couplings having protrusions that can be engaged with each other on opposing surfaces at each end of opposing rotating shafts, in which an elastic body is fixed to the protrusions of at least one of the couplings. This feature allows for stable drive transmission even when the developing device moves, and also absorbs vibrations caused by misalignment of the axes between the couplings, so there is no possibility of abnormal noise or unevenness due to vibration. In addition, it has the excellent effect of maintaining good resist performance for overlapping images in an image forming apparatus capable of forming color images.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, in which Fig. 1 is a schematic sectional view of the copying machine of the present application, Fig. 2 is an enlarged view of the lens reading unit, Fig. 3 is a plan view of the writing unit, and Fig. 4 is a schematic cross-sectional view of the copying machine of the present invention. The figure is an enlarged sectional view of the developing unit, Figure 5 is a partially cutaway perspective view of the coupled state of the coupling, Figures 6 (a) and (b) are developed views of the opposing surfaces of the coupling, and Figure 7 is the developing device. It is an explanatory view of a drive system of a sleeve. A - Original reading section B - Printer part 40 - Photosensitive drums 43 to 45 - Developing device 441 - Developing sleeve 441 ' - Shaft 450 - Abutment rollers 451.45. L--Coupling 452--Drive motor 453-Gear train 453'--Shaft 455.456--Protrusion 457--Elastic body patent applicant Konica Co., Ltd. Figure 2, Figure 2

Claims (2)

[Claims] (1) A drive transmission device including couplings having protrusions that can engage with each other on opposing surfaces at each end of opposing rotating shafts, characterized in that an elastic body is fixed to the protrusions of at least one of the couplings. Drive transmission device. (2) The drive transmission device according to claim 1, wherein the elastic body is formed into a ring shape from urethane rubber and is fitted onto a projection.