JPH01195464A - Image forming device - Google Patents

Abstract

PURPOSE:To excellently keep resist performance by separately providing driving sources for a photosensitive drum, a developing sleeve and a cleaning device and preventing the variation of load from influencing even the rotation of the developing sleeve and the photosensitive body even if the photosensitive drum generates the variation of load by the slide and separation of the cleaning blade. CONSTITUTION:As to the photosensitive drum 40, a coupling 402 provided on the end of the shaft thereof is coupled to a coupling 404 connected to a 1st driving motor 401 provided on a main body side through gear train 403. And as to the developing sleeve 441, a coupling 449 provided on the end of the shaft thereof is coupled to a coupling 453 connected to a 2nd driving motor 451 provided on the main body side through a gear train 452. The 2nd driving motor 451 is connected to a cleaning roll 48 in the cleaning device 46 through couplings 449' and 453'. Since the photosensitive drum, the developing sleeve and the cleaning roll are respectively driven by different driving sources, the variation of load of the photosensitive drum does not influence the rotation driving system of the developing sleeve. Thus, the resist performance for superposing images in the middle of forming images can be excellently maintained.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an image forming apparatus, particularly an image forming apparatus that forms a color image on the surface of a photoreceptor drum using an electrophotographic method, and then transfers the color image onto a transfer paper at once. The present invention relates to an image forming apparatus of this type.

[Conventional technology]

Generally, when forming a color image using this type of image forming apparatus, first, during the first rotation of the photoreceptor drum, the surface of the photoreceptor drum is charged with a charger, and a charger corresponding to a first color (for example, red) is charged. An image is formed and developed using a developing device containing red toner. During the second rotation, it is charged again to form a latent image corresponding to a second color (for example, blue), which is superimposed and developed using a developing device containing blue toner. During the third rotation, the toner is charged again to form a latent image corresponding to a third color (for example, black), which is superimposed and developed using a developing device containing black toner. During this third rotation, the three-color toner image is transferred to the transfer paper at the transfer section at once, and then the remaining toner is scraped off by sliding the cleaning blade and cleaning roller against the drum surface, and the next cycle is started. It is expected to move to .

In other words, the cleaning blade is in sliding contact with the drum surface at the beginning of one revolution of the photoreceptor drum, but separates from it halfway. The second round of light exchange is performed while they are separated, and the third time they make contact in the middle. Therefore, a large difference in load fluctuation appears on the photosensitive drum between when the cleaning blade slides into contact with the cleaning blade and when it separates from the cleaning blade.

[Problem that the invention seeks to solve]

However, in conventional devices, the drive system for the photoconductor drum, developing sleeve, cleaning device, and transfer paper conveyance system share a common drive source, so the load fluctuations caused by pressure contact between the photoconductor drum and cleaning roller are caused by a single drive source. As a result, when multiple colors are developed in layers on the surface of the photoreceptor drum as described above, the resist performance of overlapping images deteriorates, resulting in image deterioration. There was the problem of inviting.

As a method to eliminate the influence of such load fluctuations on the photoreceptor drum, the timing of the sliding contact and separation of the cleaning blade and cleaning roller is changed to outside the image forming area, that is, to make a color image in three rotations, and the cleaning blade and cleaning roller are lightly rotated four times. It is conceivable to scrape off the residual toner by sliding it into contact with the toner, but this poses the problem of slowing down the copying speed.

The present invention is intended to solve the above-mentioned problems, and an object of the present invention is to provide an image forming apparatus that can maintain good registration performance for overlapping images even if the load on the photoreceptor drum changes during image formation. It is said that

[Means for solving problems]

In order to achieve the above object, the present invention has a cleaning blade and a cleaning roller that come into sliding contact with the photoreceptor drum while the latent image formed on the photoreceptor drum is being developed into a toner image.
In an image forming apparatus designed to separate, at least drive sources for the photoconductor drum, the developing sleeve, and the cleaning device are provided separately, so that even if the photoconductor drum experiences load fluctuations due to sliding contact and separation of the cleaning blade, The structure is such that the rotation of the developing sleeve and photoreceptor is not affected.

〔Example〕

Next, the present invention will be described based on an embodiment shown in the accompanying drawings.

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 light can be taken out by the first mirror 7 and led out to the lens reading unit 20 via the mirror 9.9' provided in the movable mirror unit 8.

The carriage 3 and the movable mirror unit 8 are driven by pulleys 11, 12, 13, and 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 in the same direction as the carriage 4 at 1/2 the speed. 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,
and C-c hCCD 27 provided on the second reading board 26
The image is formed on each light-receiving surface. This R-chCCD
The image signals output from the C-channel CCD 25 and the C-ch CCD 27 are subjected to body bone processing in a signal processing section 28, and a color signal separated according to the toner color is output to a writing unit 29 provided in the printer B.

As shown in the third figure, the writing unit 29 includes a semiconductor laser 31, a polygon mirror 32 which is rotated by a drive motor 30 to rotate and scan the laser beam generated by the semiconductor laser 31, an fθ 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 using 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.
Similarly to the above, a latent image corresponding to the second color is formed on the surface. '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 FIGS. 4 and 5, the developing units 44 to 45 include a developing sleeve 441 with a magnet embedded in its outer periphery, a main stirring member 443 for the developer 442, and a main agitating member 443 for moving the developer from one end in the developing width direction to the other end. A first conveying means 4 that conveys in one direction toward
44, a second conveying means 445 for conveying the developer in the opposite direction to the first conveying means 444.

AC and DC biases 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 .

The image forming unit including the photosensitive drum 40 and the charging device 41 and developing devices 44 to 45 located around the photosensitive drum 40 is placed on a retractable rail 450 and can be pulled out for jam processing or the like. When this image forming unit is stored, the photosensitive drum 40
A coupling 402 provided at the end of the shaft is coupled to a coupling 404 connected via a gear train 403 to a first drive motor 401 provided on the main body side. The first drive motor 401 serves as a drive source for the drive side roller 52' of the paper feed belt, the paper feed roller 53, the drive side roller 58a of the fixing device 58, and the paper discharge roller 59a.

Further, the coupling 449 provided at the shaft end of the developing sleeve 441 connects with the second drive motor 45 provided on the main body side.
1 through a gear train 452.
join to. This second drive motor 451 is connected to the main stirring member 443 in the developing units 43 to 45 through the developing sleeve 441.
, drives the first conveying means 444 and the second conveying means 445, and is also connected to a cleaning roller 48 in the cleaning device 46 via couplings 449' and 453', and the roller 48 is connected to the cleaning blade 4.
7 and the cleaning roller 48 are gear-coupled to a drive shaft of a rotating cam (not shown) that slides the photosensitive drum 40 into or out of contact with the photosensitive drum 40 .

As the first drive motor 401, it is preferable to use a DC motor that is capable of feedback control and has good rotational accuracy, but as the second drive motor 451, a small and lightweight AC motor that is inexpensive is preferable. Satisfied using a motor.

The three-color toner image developed in this way is transferred to the transfer section 51.
At the time, the recording sheets are separated one by one by the paper feeding belt 52 of the paper feeding section 50, and are transferred at once onto the recording paper 55 fed through the guide plate 54 with the timing taken by the paper feeding roller 53. Thereafter, the recording paper is separated from the photosensitive drum 40 by the separation pole 56, placed on the conveyor belt 57, and transferred to the fixing device 5.
8, the paper is fixed by heat and pressure with fixing rollers 58a and 58b, and then transferred to a paper output roller 59 as a color hard copy.
It is held between a 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 48 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, the surface of the photoreceptor drum 40 is charged by the charger 41 to form a latent image corresponding to a first color (for example, red), and the latent image is developed by the developer 43 containing red toner.
During the second rotation, it is charged again to produce a second color (e.g. blue)
A developing device 4 that forms a latent image corresponding to the blue toner and contains blue toner.
4, and develop the third color (
For example, in the process of forming a latent image corresponding to black toner and developing it in a developing device 45 containing black toner, the photoreceptor drum 4
Even if a load change occurs due to sliding contact or separation of the cleaning blade 47, the photoreceptor drum and the developing sleeve are each driven by separate drive sources, so the influence of the load change on the photoreceptor drum will not affect the rotational drive of the developing sleeve. It doesn't even extend to the system. Even if load fluctuations occur due to pressure contact and separation of the cleaning roller, the drive sources for the photosensitive drum and the cleaning roller are separate, so the load fluctuations that affect the light emitting body can be reduced.

〔Effect of the invention〕

As described above, the present invention allows the cleaning blade to slide into and away from the photoreceptor drum while the latent image formed on the photoreceptor drum is being developed into a toner image.

This image forming apparatus is characterized in that at least drive sources for the photoconductor drum, the developing sleeve, and the cleaning device are provided separately, so that the photoconductor drum does not cause load fluctuations due to sliding contact and separation of the cleaning blade. However, the influence does not extend to the rotational drive system of the developing sleeve. Therefore, the excellent effect of maintaining good resist performance for overlapping images during image formation is achieved.

[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 a side sectional view of the developing device, and FIG. 5 is a plan sectional view of the developing device. A-Document reading section B--Printer part 40--Photoconductor drum 41-Charger 43 to 45--Developer 46-Cleaning device 47--Cleaning blade 48-Cleaning roller 441-Developing sleeve 442-- -Developer 443-Main stirring member 44/l--First conveying means 445--Second conveying means 446--Doctor blade 447--Scraper 448-m-Partition wall 401.451-- Drive motor 403.452--gear train patent applicant Konica Co., Ltd. Figure 2

Claims (2)

[Claims] (1) While the latent image formed on the photoreceptor drum is being developed into a toner image, the cleaning blade comes into sliding contact with the photoreceptor drum.
An image forming apparatus configured to separate from each other, characterized in that drive sources for at least the photosensitive drum and the developing sleeve are provided separately. (2) Claim 1, wherein the drive source for the photosensitive drum is a DC motor, and the drive source for the developing sleeve is an AC motor.
The image forming apparatus described in .