JP2003167448A - Image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent, despite frequent formation of monochrome images, deterioration of parts relating to transfer and to reduce running costs. <P>SOLUTION: In the image forming device 100 which has a photoreceptor drum 1 and a transfer drum 2 for holding and carrying a recording material and transfers an image in a transfer part 31 between the photoreceptor drum 1 and transfer drum 2, the transfer drum 2 can be brought into contact with the photoreceptor drum 1 and separated therefrom and has a resist roller 29 for carrying the recording material to the transfer part 31 while the transfer drum 2 is separated from the photoreceptor drum 1 and a transfer corona electrifier 55 for transferring a toner image on the photoreceptor drum 1 to the recording material while the transfer drum 2 is separated from the photoreceptor drum 1. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus having an image carrier and a recording material carrier.

[0002]

2. Description of the Related Art A conventional image forming apparatus having a recording material carrier composed of a dielectric film or the like for carrying and conveying a recording material will be described with reference to the drawings. FIG. 6 is a sectional view of a conventional image forming apparatus.

As shown in FIG. 6, the image forming apparatus 200 includes
It has a photosensitive drum 101 as an image carrier. The photosensitive drum 101 is rotationally driven clockwise at a predetermined peripheral speed by a driving unit (not shown). Further, the transfer drum 102 as a recording material carrier having the same diameter as the photosensitive drum 101.
Are arranged in contact with the photoconductor drum 101, and in this contact state, drive is transmitted by gear transmission means (not shown), and is driven to rotate counterclockwise at the same peripheral speed as the photoconductor drum 101.

Next, the original 103 is scanned by the original illumination lamp 104, and the reflected light thereof is reflected by the first mirror 105 and the second mirror 1.
The image is read by the photoelectric sensor 109 after being bent by 06 and the third mirror 107 and adjusted in focus by the lens 108. Generally, in the case of a full-color original, four scanning operations are performed to read a magenta component (M component), a cyan component (C component), a yellow component (Y component), and a black component (K component) in the original document. Be done.

First, a laser beam is emitted from the laser oscillator 110 corresponding to the image of the magenta component read by the photoelectric sensor 109. The laser beam is scanned by the rotating polygon mirror 111 through the mirror 112 onto the photoconductor drum 101 to form a latent image in the scanning direction on the photoconductor drum 101. Then, the latent image on the photosensitive drum 101 is developed as a toner image by the magenta developing device 113. On the other hand, the recording material is loaded in the upper cassette 117 and the lower cassette 118, but the lower cassette 118 will be described here.

The recording materials stacked in the lower cassette 118 are separated one by one in the feeding / separating section 122 and conveyed to the registration rollers 129 by the vertical pass rollers 124, 125, 126, the horizontal pass roller 127 and the pre-registration roller 128. ing.

The position of the recording material is the photosensitive drum.
After the timing is adjusted by the registration roller 129 so as to match the image position on the 101, it is conveyed onto the transfer drum 102, and is adsorbed onto the transfer drum 102 by the adsorption roller 130.

Next, in the transfer unit 131, a bias current is applied from the inside of the transfer drum 102 by a transfer corona charger 155 as a transfer means, and a magenta toner image developed on the photosensitive drum 101 is transferred onto the transfer drum 102. It is transferred to the recording material adsorbed on. Then, the recording material is rotated while being attracted to the transfer drum 102. The transfer unit 131
At, the toner image not transferred and remaining on the photosensitive drum 101 is removed and collected by the cleaner 135.

Then, the photosensitive drum 1 is charged by the primary charger 136.
After the potential on 01 is made uniform, a latent image corresponding to the image of the cyan component is formed on the photosensitive drum 101 in the same process as the image of the magenta component, and this latent image is formed by the cyan developing device 114. It is developed as a toner image. And
In the transfer section 131, the cyan toner image is transferred onto the recording material attracted onto the transfer drum 102 that has rotated once.

Similarly, a yellow component image and a black component image are also transferred onto the recording material, and all four color component images are transferred onto the recording material. The image forming apparatus 200 is
In addition to the four-color developing device, a yellow developing device 115 and a black developing device 116 are provided. Here, the images of the four color components on the original 103 are controlled to be formed on the photosensitive drum 101 by the laser beam so that they all match on the recording material.

The recording material on which the four color toner images have been transferred through the above process is separated and separated from the transfer drum 102 by the push-up roller 132 and the separation claw 133, and is conveyed to the fixing device 137 by the conveying section 134. Then, in the fixing device 137, the recording material is nipped and conveyed by the fixing roller 143 and the heater 146 which are heated by the heater 144 and the pressure roller 145 which is heated, and the toner image carried on the recording material is It dissolves and fixes on the recording material. And the fixing device 13
The recording material on which the toner image has been fixed by 7 is discharged by the discharge roller 139 to the outside of the main body of the image forming apparatus.

The above is the process directly related to image formation. During such an operation, the surface of the transfer drum 102 is soiled by the toner scattered in the machine and the fog toner. Therefore, if left unattended, it adheres to the back surface of the next recording material. , The back will be dirty. Therefore, after the above-described series of image forming steps, the transfer cleaner 151 contacts the transfer drum 102, and
The surface of the transfer drum 102 is cleaned by rotating more than one revolution.

After a series of image forming operations is completed in this way, if the transfer drum 102 is left in contact with the photosensitive drum 101 for a long time by a transfer drum attaching / detaching mechanism using a cam or the like (not shown), the photosensitive drum This is because electric charges that cannot be removed remain on 101, which results in an abnormal image. To prevent this, when the device is stopped, they are separated by a predetermined distance.

Although the full-color image forming process has been described above, the single-color image forming process is performed as follows. That is, in the case of a single-color image, it is not necessary to superimpose the transferred images. Therefore, the same is true up to the point where the recording material is adsorbed to the transfer drum 102, but one color toner image is transferred at the transfer unit 131. The recording material is immediately separated and separated from the transfer drum 102 by the push-up roller 132 and the separation claw 133. After that, the fixing unit 137 is fed by the transport unit 134.
Be transported to. Further, the transfer cleaning process is performed and the transfer drum 102 is separated from each other as in the case of full color.

[0015]

However, the transfer drum 102 abuts on the photosensitive drum 101 at least once during the formation of a single-color image, and the transfer cleaning step thereafter causes the transfer drum 102 to rotate at the same time. Since the drum 101 also rotates, there is a problem that the transfer drum 102 and the photoconductor drum 101 are worn and deteriorated more than necessary.

Particularly in recent years, the tendency for full-color image forming apparatuses to be introduced into general offices has increased, and in this case, even in the case of full-color image forming apparatuses, the usage rate of monochromatic images, especially black-and-white images, has been increasing.

Under the above-mentioned conditions of use, if the transfer cleaning step and the rotating step of the photosensitive drum 101 associated therewith are performed for each operation as described above, these parts are consumed and deteriorated more than necessary, resulting in Since it is forced to replace it at an early stage, there is a problem that the running cost per drawing is high.

Therefore, an object of the present invention is to prevent deterioration of parts relating to transfer even if a monochromatic image is frequently formed and to reduce running costs.

[0019]

A typical constitution of the present invention for achieving the above object comprises an image carrier and a recording material carrier for carrying and conveying a recording material. In an image forming apparatus that transfers an image at a transfer portion between a recording material carrier and the recording material carrier, the recording material carrier is capable of contacting and separating from the image carrier, A conveying unit that conveys the recording material to the transfer unit when the body is separated from the image carrier; and a toner image on the image carrier when the recording material carrier is separated from the image carrier. And a transfer means for transferring to a recording material.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION (First Embodiment) A first embodiment of the present invention will be described in detail with reference to the drawings. Figure 1 is the first
2A and 2B are explanatory views of the vicinity of a transfer unit of the embodiment, FIG. 2 is an explanatory view of a configuration of a transfer drum, and FIG. 5 is an explanatory view of an image forming apparatus. First, the configuration of the image forming apparatus and the operation for forming a color image will be described, and then the operation for forming a monochrome image will be described.

As shown in FIG. 5, the image forming apparatus 100 includes
It has a photosensitive drum 1 as an image carrier. The photosensitive drum 1 is rotationally driven clockwise at a predetermined peripheral speed by a driving unit (not shown). Further, a transfer drum 2 as a recording material carrier having the same diameter as the photosensitive drum 1 is arranged in contact with the photosensitive drum 1, and in this contact state, drive is transmitted by gear transmission means (not shown), The photosensitive drum 1 is driven to rotate counterclockwise at the same peripheral speed.

Next, the original 3 is scanned by the original illumination lamp 4, the reflected light thereof is bent by the first mirror 5, the second mirror 6 and the third mirror 7, and the focus is adjusted by the lens 8, and then the photoelectric conversion is performed. The image is read by the sensor 9. Generally, in the case of a full-color original, four scanning operations are performed to read a magenta component (M component), a cyan component (C component), a yellow component (Y component), and a black component (K component) in the original document. Be done.

First, a laser beam is emitted from a laser oscillator 10 corresponding to an image of a magenta component read by a photoelectric sensor 9, and a rotating polygon mirror 11 causes a latent image in the scanning direction via a mirror 12 to a photoconductor. Drum 1
Formed on. Then, the latent image on the photosensitive drum 1 is developed as a toner image by the magenta developing device 13. On the other hand, the recording material is loaded in the upper cassette 17 and the lower cassette 18, but the lower cassette 18 will be described here.

The recording materials loaded in the lower cassette 18 are separated one by one in the feeding / separating section 22, and the vertical pass rollers 24, 25, 26, the horizontal pass roller 27 and the pre-registration roller 28 are separated.
It is conveyed to the registration roller 29 by.

The timing of the recording material is adjusted by a registration roller 29 as a conveying means so that the position of the recording material coincides with the image position on the photoconductor drum 1, and then the recording material is conveyed onto the transfer drum 2 by the suction roller 30. Transfer drum 2
Adsorbed on.

Next, in the transfer section 31, a bias current is applied from the inside of the transfer drum 2 by the transfer corona charger 55, and the magenta toner image developed on the photosensitive drum 1 is adsorbed on the transfer drum 2. It is transferred to the existing recording material. Then, the recording material rotates while being attracted onto the transfer drum 2 as it is. In the transfer unit 31, the toner image remaining on the photosensitive drum 1 without being transferred is removed and collected by the cleaner 35.

Then, the photosensitive drum 1 is charged by the primary charger 36.
After the upper potential is made uniform, a latent image corresponding to the image of the cyan component is formed on the photoconductor drum 1 in the same process as the image of the magenta component.
14 develops as a toner image. And the transfer part
At 31, the cyan toner image is transferred onto the recording material adsorbed on the transfer drum 2 that has rotated once.

Similarly, the yellow component image and the black component image are also transferred onto the recording material, and the four color component images are all transferred onto the recording material. The image forming apparatus 100 is
In addition to the four-color developing device, a yellow developing device 15 and a black developing device 16 are provided. Here, the images of the four color components on the original 3 are controlled so as to be formed on the photosensitive drum 1 by the laser beam so that they all match on the recording material.

The recording material on which the toner images of four colors have been transferred through the above process is separated and separated from the transfer drum 2 by the push-up roller 32 and the separation claw 33, and is fixed by the conveying section 34.
Transported to 37. Then, in the fixing device 37, the fixing roller 43 and the heater 46 heated by the heater 44.
The recording material is nipped and conveyed by the pressure roller 45 heated by, and the toner image carried on the recording material is melted and fixed on the recording material. The recording material on which the toner image has been fixed by the fixing device 37 is discharged by the discharging roller 39 to the outside of the image forming apparatus main body.

The above is the image forming process. During such an operation, the surface of the transfer drum 2 is soiled by the toner scattered in the machine and the fog toner. It becomes dirty. Therefore, after the above-described series of image forming steps, the transfer cleaner 51 contacts the transfer drum 2 and the transfer drum 2 rotates one or more times to clean the surface of the transfer drum 2.

After a series of image forming operations is completed in this way, if the transfer drum 2 is left in contact with the photosensitive drum 1 for a long time by the transfer drum attaching / detaching mechanism using a cam or the like (not shown), the photosensitive drum This is because unremovable charges remain on the surface 1 and the image becomes abnormal. To prevent this, the device is separated by a predetermined distance when the device is stopped.

(Structure around transfer section) The structure around the transfer section 31 will be described with reference to FIGS. 2A is a detailed view of a rotating portion of the transfer drum 2 as shown in FIG. The transfer drum 2 includes a front ring 5 as a pair of rings.
7. A rear ring 58 is provided. The pair of rings are connected by a connecting plate 54 as a connecting member so that the front and rear can rotate integrally, and then, as shown in FIG. 2B, a recording material carrying sheet 53 is wound. . Recording material carrying sheet
As the 53, a flexible one is used so as to be evenly attached to the photosensitive drum 1. The connecting plate 54 has a slit in the longitudinal direction.
54a is provided. Since the front and rear ends of the recording material carrying sheet 53 are fixed to the respective ends in the rotational direction of the connecting plate 54, the slits 54a are exposed when the recording material carrying sheet 53 is wound.

Next, as shown in FIG. 1, a transfer corona charger.
Reference numeral 55 is connected to a high-voltage power source (not shown) and applies a bias current to the photosensitive drum 1 by corona discharge. Further, as will be described later, the transfer guide 56 uses a transfer section in which the recording material is opposed to the photosensitive drum 1 and the transfer drum 2 in a mode in which the recording material is not attracted to the recording material carrying sheet 53.
Guide to 31.

(Operation of Image Forming Apparatus) The operation of the image forming apparatus will be described with reference to FIG. First, full-color image formation in which four color toners of YMCK are overlaid is as described above. Next, a monochrome image forming mode, for example, a monochrome image forming operation will be described.

At the time of forming a black and white image, the transfer drum 2 is not pressed and is operated while being separated from the photosensitive drum 1. At this time, as shown in the figure, the transfer drum 2 is stationary with a predetermined distance d from the photosensitive drum 1. The optimum value of this distance d is determined by the toner condition and the condition of the recording material to be passed, but it is preferably about 1.5 to 2.0 mm.

Next, the connecting plate 54 can be stopped at a position where its slit 54a substantially opposes the photosensitive drum 1, and a bias current can be directly applied to the back surface of the recording material. Suction roller
Unlike the case of forming a full-color image, 30 is separated from the transfer drum 2.

Here, when the recording material is conveyed from the registration roller 29 and sent to the vicinity of the transfer drum 2, the transfer drum 2 does not rotate unlike the case of forming a full-color image, and the recording material is the surface portion of the transfer drum 2. Is used as one guide surface and is guided together with the transfer guide 56 on the other guide surface, and is conveyed to the transfer unit 31 where the photoconductor drum 1 and the transfer drum 2 face each other. Here, due to the rigidity of the recording material, when the recording material travels in the direction away from the transfer portion 31, it is correctly guided to the transfer portion 31 by the transfer guide 56.

At this time, when a high voltage is applied to the transfer corona charger 55, the recording material is electrostatically urged toward the photosensitive drum 1, and at the same time, the toner image on the photosensitive drum 1 is transferred. . After passing through the transfer section 31, the recording material is not adsorbed to the transfer drum 2 unlike in the case of full color, and thus is easily separated by the separation claw 33 and is conveyed to the fixing device 37. Subsequent operations are the same as in full-color image formation.

As described above, according to the present invention, the transfer drum 2 can be brought into contact with and separated from the photosensitive drum 1, and when the transfer drum 2 is in the separated state, it does not rotate. The transfer drum 2 is not rotated at the time of forming a single-color image, and auxiliary processes such as transfer cleaning associated therewith are also unnecessary. As a result, the transfer drum 2
Further, the photosensitive drum 1 is not deteriorated or worn more than necessary, and as a result, the running cost of the monochromatic image forming characters is comparable to that of the monochromatic image dedicated image forming apparatus.

The transfer drum 2 has a pair of rotating front and rear rings 57 and 58, a connecting plate 54 for connecting the rings in a direction orthogonal to the moving direction of the recording material, and these rings and the connecting plate 54. And a flexible recording material carrying sheet 53 installed in a housing consisting of a connecting plate 54 and a slit 54a in a direction orthogonal to the moving direction of the recording material in a part of its rotating direction. When the transfer drum 2 is separated, the slit 54a is stopped at a position facing the photosensitive drum 1, and the toner image on the photosensitive drum 1 is transferred onto the recording material by the transfer corona charger 55 provided inside the transfer drum 2. As a result, it is possible to provide an inexpensive and highly reliable image forming apparatus without having a dedicated transfer charging unit even when forming a single color image.

(Second Embodiment) A second embodiment of the present invention will be described in detail with reference to the drawings. FIG. 3 is an explanatory diagram of the vicinity of the transfer portion of the second embodiment, and FIG. 4 is an explanatory diagram of the transfer charging roller. The configurations described in the above-described embodiment are denoted by the same reference numerals and the description thereof will be omitted.

(Structure around transfer unit) The structure around the transfer unit 31 will be described with reference to FIGS. 3 and 4. FIG. As shown in FIG.
Inside the transfer drum 2, a transfer charging roller 60 as a transfer unit is provided near the transfer unit 31. Further, the transfer charging roller 60 includes a conductive charging roller 61 and a charging roller 61.
The charging roller 61 is rotatably supported by the roller base 62 and slidable by the roller pressing spring 63 inside the slit 62a. The transfer charging roller 60 is biased toward the photosensitive drum 1 by a roller pressure spring 63.

A bias voltage is applied to the charging roller 61 from a contact (not shown), and a current is applied to the photosensitive drum 1 via the recording material carrying sheet 53 and the recording material, whereby the photosensitive drum 1
The upper toner image is transferred to the recording material.

Next, the operation of the image forming apparatus having such a configuration will be described. First, the operation of forming a full-color image by superposing four color toners of each of YMCK components is the same as that of the above-described embodiment, and therefore the description thereof is omitted. In this case,
In the transfer charging roller 60 shown in FIG. 4, since the charging roller 61 is biased by the roller pressure spring 63 as described above,
As the transfer drum 2 rotates, the connecting plate 54 transfers the transfer charging roller.
The charging roller 61 is retracted when passing through the 60th copy.

Next, a monochrome image forming mode, for example, a monochrome image forming operation will be described. When forming a black and white image,
Similar to the first embodiment, the transfer drum 2 is operated without being pressed and being kept separated from the photosensitive drum 1.

Next, the connecting plate 54 is stopped at a position where its slit 54a substantially opposes the photosensitive drum 1, whereby the transfer charging roller 60 inside the transfer drum 2 is slit 54a.
A bias voltage can be applied to the back surface of the recording material by projecting from.

Here, when the recording material is conveyed from the registration roller 29 and sent to the vicinity of the transfer drum 2, the transfer drum 2 does not rotate and the recording material is guided by the surface portion of the transfer drum 2 unlike the case of forming a full-color image. Then, it is conveyed to the transfer portion 31 of the photosensitive drum 1 and the transfer drum 2 which face each other.
Here, when the recording material travels in a direction away from the transfer portion 31 due to the rigidity of the recording material, it is correctly guided to the transfer portion 31 by the transfer guide 56. At this time, when a high voltage is applied to the transfer charging roller 60, the toner image on the photosensitive drum 1 is transferred.

According to this embodiment, the transfer charging roller 60
By the urging force of the recording material, the recording material comes into contact with the photosensitive drum 1 more reliably, so that a better transferred image can be obtained. The subsequent operation is the same as the image forming process of the first embodiment.

(Other Embodiments) In the above-described embodiments, the image forming apparatus has been described by taking a copying machine as an example. However, the image forming apparatus is not limited to this and may be an image forming apparatus such as a printer or a facsimile machine.

[0050]

As described above, in the present invention, the recording material carrier can be brought into contact with and separated from the image carrier, and the recording material carrier is separated from the image carrier. And a transfer means for transferring the toner image on the image carrier to the recording material in a state where the recording material carrier is separated from the image carrier. Therefore, for example, when a monochromatic image that does not need to carry the recording material is formed, transfer can be performed in a state where the image carrier and the recording material carrier are separated from each other, so that a monochromatic image is formed. It is possible to prevent the deterioration of the parts related to the transfer even if it is frequently performed, and to reduce the running cost.

[Brief description of drawings]

FIG. 1 is an explanatory diagram in the vicinity of a transfer unit according to a first embodiment.

FIG. 2 is an explanatory diagram of a configuration of a transfer drum.

FIG. 3 is an explanatory diagram of the vicinity of a transfer unit according to the second embodiment.

FIG. 4 is an explanatory diagram of a transfer charging roller.

FIG. 5 is a schematic explanatory diagram of an image forming apparatus.

FIG. 6 is a schematic explanatory diagram of a conventional image forming apparatus.

[Explanation of symbols]

1 ... Photosensitive drum 2 ... Transfer drum 3… manuscript 5 ... 1st mirror 6… Second mirror 7 ... Third mirror 8 ... Lens 9 ... Photoelectric sensor 10… Laser oscillator 11… Polygon mirror 12… Mirror 13 ... Magenta developer 14 ... Cyan developer 15… Yellow developer 16… Black developer 17… Upper cassette 18 ... Lower cassette 22… Feed separation unit 24… Vertical path roller 25… Vertical path roller 26… Vertical path roller 27… Side pass roller 28… Roller before registration 29… Registration roller 30… Suction roller 31… Transfer unit 32… Oshiage roller 33… Separation claw 34 ... Conveyor 35 ... Cleaner 36… Primary charger 37… Fixing device 39… Ejection roller 43… Fixing roller 44… Heater 45… Pressure roller 46… Heater 51… Transcription cleaner 53… Recording material carrying sheet 54… Connecting plate 54a ... slit 55… Transfer corona charger 56… Transfer guide 57… Front ring 58… Rear ring 60… Transfer charging roller 61… Charging roller 62… Roller base 62a ... slit 63… Roller pressure spring 100 ... Image forming device

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 2H030 AD05 BB43 BB44 BB53 BB54                       BB56 BB63                 2H200 FA09 GA23 GA34 GA47 GA50                       GB12 GB22 GB25 HA02 HA12                       HA28 HB03 HB12 HB22 JA02                       JA26 JB03 JB13 JB16 JB20                       JB26 JB32 JB39 JB40 JB42                       JB43 KA03 KA14 LA24 LA30                       LB02 LB09 LB13 MB01

Claims (4)

[Claims] 1. An image forming apparatus having an image carrier and a recording material carrier that carries and conveys a recording material, wherein an image is transferred at a transfer portion between the image carrier and the recording material carrier. In the above, the recording material carrier can be brought into contact with and separated from the image carrier, and conveys the recording material to the transfer section in a state where the recording material carrier is separated from the image carrier. An image forming apparatus comprising: a conveying unit; and a transfer unit that transfers a toner image on the image carrier to the recording medium in a state where the recording medium carrier is separated from the image carrier. 2. The image forming apparatus according to claim 1, wherein the recording material carrier does not rotate in a state of being separated from the image carrier. 3. The image forming apparatus according to claim 2, wherein in a state where the recording material carrier is separated from the image carrier, a surface of the recording material carrier that carries the recording material is the recording material. An image forming apparatus, which also functions as a guide surface for guiding an image carrier. 4. The image forming apparatus according to claim 1, wherein the recording material carrier connects a pair of rotating rings and the rings in a direction orthogonal to a moving direction of the recording material. A connecting member, and a flexible recording material-carrying sheet provided in the housing with the ring and the connecting member as a housing, wherein the connecting member is arranged in the moving direction of the recording material. Slits are provided in a direction orthogonal to each other, and in a state where the recording material carrier is separated from the image carrier, the slit is stopped at a position facing the image carrier, and the transfer means inside the recording material carrier causes the slit to stop. An image forming apparatus, which transfers a toner image on the image carrier to a recording material.