JPH06100863B2 - Multicolor recorder - Google Patents

Description

The present invention relates to a multicolor recording apparatus using an electrophotographic recording system,
In particular, the present invention relates to a device structure that does not complicate the device structure and can perform clear multicolor recording without color mixture for a long time at high speed.

In recent years, with the diversification of information, the color of recorded information such as characters, symbols and images is changed as needed, and recording is performed on the same recording paper in a color in which characters, symbols and images of different colors are mixed. Therefore, various apparatuses or systems for multicolor recording have been proposed.

In electrophotographic recording, generally, an electrostatic latent image is formed by performing exposure corresponding to an information image to be recorded on a photosensitive drum, which is an image carrier, to which a constant charging potential is uniformly applied, and the latent image is formed. After a visible image is formed with toner by a developing device, this visible image is transferred to a recording sheet for recording.

Therefore, a plurality of image forming units each including a latent image forming unit and a developing device are provided around the photosensitive drum, and each image forming unit forms a visible image with toner of different colors on the surface of the photosensitive drum. By transferring the visible image to a recording sheet,
Multicolor recording can be obtained.

In such a multicolor recording apparatus, if the rabbit angle and the toner in the developer used in the previous developing step are mixed in the developer in the next developing step and the accumulated amount of the mixed toner increases, the toner There is a problem that color mixture is likely to occur in a visible image, and it is desired to eliminate such inconvenience.

[Conventional technology]

As a conventional apparatus for performing high-speed multicolor recording by the electrophotographic recording method, the present applicant has already proposed it in JP-A-52-106743 and JP-A-58-116553.

That is, as shown in FIG. 4, the conventional multi-color recording apparatus based on the electrophotographic recording system has an initial charger 2 and a first charger 2 around a photosensitive drum 1 made of a photosensitive layer such as selenium (Se). Exposure unit 3 and development unit 4, recharger 5, second exposure unit 6 and development unit 7, recharger 8, third exposure unit 9 and development unit 10.
And transfer device 11, fixing device 12, AC static eliminator 13, cleaner 1
4, the optical static eliminator 15 is arranged in order, and the developing devices 4, 7 and
The toner colors of the developer used in 10 are yellow, magenta, and cyan.

First, rotate the photosensitive drum 1 in the direction of the arrow to
A constant initial charging potential level Vs on the surface by the initial charger 2.
The entire surface is uniformly charged.

Next, negative exposure corresponding to the first color information is performed on the surface of the photosensitive drum 1 by the first exposure unit 3, and the charging potential is set to approximately 0v.
To form a first latent image attenuated to. Thereafter, the first latent image is subjected to magnetic brush reversal development by a first developing device 4 using a two-component magnetic developer in which a toner of a first color and a carrier are mixed to form a first toner visible image. To do.

Next, recharging is performed by the recharging device 5 so that the potential of the first toner visible image portion becomes substantially the same as the background potential Vs on the photosensitive drum 1, and the re-charging device 5 forms a visible toner on the already formed first toner visible line. ,
Prevents other toner from adhering.

The negative exposure corresponding to the second color information is then performed by the second exposure unit 6 on the surface of the photosensitive drum 1 that has been recharged to form a second latent image, and the second latent image is formed into a second latent image. Magnetic brush reversal development is performed by the second developing device 7 using a two-component magnetic developer in which color toners and carriers are mixed to form a second toner visible image.

Further, recharging is performed by the recharging device 8 so that the potential of the second toner visible image portion becomes substantially the same as the background potential Vs on the photosensitive drum 1. This recharging can prevent other toner from adhering to the second toner visible image.

Next, a negative exposure corresponding to the third color information is performed on the surface of the photosensitive drum 1 by the third exposure section 9 to form a third latent image, and the third latent image is formed by the toner of the third color. Magnetic brush reversal development is performed by a third developing device 10 using a two-component magnetic developer in which a toner and a carrier are mixed to form a third toner visible image.

In this way, the first and
The visible images of the second and third toners are collectively transferred onto the recording paper 16 by the transfer device 11 and further fixed by the fixing unit 12 to record the three color information.

On the other hand, the toner remaining on the surface of the photosensitive drum 1 is neutralized by the AC static eliminator 13 and removed by cleaning with the cleaner 14, and all charges on the surface of the photosensitive drum 1 are removed by the optical static eliminator.
The static electricity is erased by 15 and the next recording cycle starts.

In the above recording device, the first color toner or the second color toner is used.
The toner of the color is the second developing device 7 or the third developing device 10.
In order to prevent the color mixture of the visible images of the second and third toners caused by mixing and accumulating inside the toner, the present applicant also has a method of separating the mixed color toners from the respective developers.
It has already been proposed by Japanese Patent Application Laid-Open No. 58-105173 and Japanese Patent Application No. 59-128592.

That is, the above separating method is applied to the first, second, and third color toners 21, 22, in the first developer, the second developer, and the third developer.
This is done by selecting the triboelectric charging series of 23 and the first, second and third carriers 24, 25 and 26 as shown in FIG.

The toners 21, 22, and 23 of the first, second, and third colors are positively charged by frictional charging with the first carrier 24, the second carrier 25, and the third carrier 26, respectively. Further, for example, when the toner 21 of the first color is mixed in the second developing device 7, the polarity is reversed to the negative polarity or attenuated due to the frictional charging with the second developer.

Therefore, the toner 21 of the first color of the negative polarity is
The electrostatic charge is electrostatically coupled to the toner 22 of the second color, and the apparent charge amount becomes almost 0. As a result, the coupling force with the second carrier 25 is weakened, and the toners 21 and 22 of the first and second colors are statically charged. The toner of the first color 21 that remains electrically connected or has a charge amount of about 0
Is scattered and separated from the developing roller in the second developing device 7 by the centrifugal force, and the mixed toner 21 of the first color is not accumulated in the second developing device 7. Even if 22 is mixed in the third developing device 10, similar scattering separation is performed.) Even if the above recording operation is repeated for a long period of time, it is possible to stably perform good three-color information recording without color mixture. ing.

[Problems to be solved by the invention]

By the way, in the multi-color recording apparatus as described above, generally, character information of black and the like is relatively often recorded, and conventionally, black obtained by combining three primary colors of yellow, magenta and cyan is used as black recording. However, since this black does not become a completely black color, development using a developer including a recharger, a fourth exposure section and black toner is provided after the third development section 10 in the recording apparatus. Attempts have been made to arrange the parts so as to obtain a clear black recording.

However, if the image forming function unit for recording the black character information is added in this way, not only does the complicated apparatus configuration having many image forming function units around the photosensitive drum become more complicated, In addition, the first to fourth developer in so-called first to fourth developers for separating and removing different color toner mixed in each developing unit after the second developing unit 7 to prevent color mixture.
It is necessary to select the toner of this color and the first to fourth carriers in accordance with the triboelectrification series shown in FIG. 5, and many toners and carriers having such triboelectrification series are procured and manufactured. It was very difficult.

[Means for solving problems]

The above problems have at least two image carriers, one of which has a plurality of developing units, and the toner and the carrier used in the plurality of developing units are arranged so that triboelectrification series are alternately arranged. The toner of different colors, the plurality of developing units form images of a plurality of colors on the image carrier, and then collectively transfer the image. The other image carrier has a plurality of developing units. Then
The toner and the carrier used in the plurality of developing units are selected so that the triboelectrification series are alternately arranged, and the colors of the respective toners are made different, so that the plurality of developing units form the plurality of color toners on the image carrier. After forming an image, the image is transferred so as to overlap with the image transferred by the one image carrier, and a single latent image forming exposure unit is arranged in the exposure optical path for at least two image carriers through a switch. This is a color recording apparatus, which is solved by setting the arrangement of the triboelectric charging series independently for each image carrier.

[Action]

That is, a plurality of image carriers can be exposed by forming a single exposure unit through an optical path switch, and pattern latent images of different colors can be formed. Then, by providing a plurality of image carriers, the developing portions of respective colors using the developer containing the color toners of cyan, magenta, yellow, and black are separately arranged, and one of the image carriers is disposed. When forming images of multiple colors on one surface and transferring them all at once, by providing the toner and the carrier of the developer that forms the image on the image carrier of multiple colors with a triboelectrification series, it becomes The number of toners and carriers that need to be arranged can be reduced, color mixing can be prevented even in a multicolor recording apparatus, and good printing can be stably performed.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a schematic configuration diagram showing an embodiment of a multicolor recording apparatus according to the present invention.

In order to eliminate the complication of the structure of the apparatus of the present invention, as shown in the figure, two image carriers composed of photosensitive layers such as selenium (Se) or SeTe, that is, the first and second photosensitive drums are used. 31, 32 are arranged in parallel in the running direction of the recording paper 50.

Further, around the first photosensitive drum 31, there are an initial charger 33, a first developing section 34 and a second developing section 35, and a transfer section 36, an AC static eliminator 37, a cleaner 38 and an optical static eliminator 39. In the same manner, the initial chargers are also arranged around the second photosensitive drum 32 in the same order.
40, a third developing unit 41 and a fourth developing unit 42, and a transfer unit 4
3, AC static eliminator 44, cleaner 45, and optical static eliminator 46 are arranged in order.

Further, as a latent image forming means for both the photosensitive drums 31 and 32, a single latent image composed of, for example, a He-Ne gas laser, a semiconductor laser, or the like is provided via an optical path switch 48 having a mirror reversing mechanism in the exposure optical path. The forming exposure unit 49 is arranged so that pattern latent images of different colors of the information image to be recorded can be formed alternately on both the photosensitive drums 31 and 32.

Each of the developers used in the first developing section 34 to the fourth developing section 42 contains, for example, toner in the order of yellow, magenta, cyan, and black, and the carrier and toner of each developer are , The two developing units 34 and 35 disposed on the photosensitive drums 31 and 32, and the second developing units 41 and 42
First and second color toners 51 and 52 and first and second carrier 53 and 54
And the third and fourth color toners 55 and 56 and the third and fourth carrier 5
7, 58 are selected so as to have independent triboelectric charging series for each photosensitive drum, as shown in FIG. 2, so that the first, third, and third mixed in the second and fourth developing units 35, 42 are selected. The color toners 51 and 55 are
During stirring in the second and fourth developing devices 35 and 42 having different orders in the triboelectric charging series, the triboelectric charging with the second and fourth color toners 52 and 56 causes the first and third color toners 51, The polarity of 55 is reversed and becomes negative. In this state, if the developer is further stirred, the polarities of the first and third color toners 51 and 55 and the positive polarity toners 51 and 55 are reversed.
The second and fourth color toners 52 and 56 are electrostatically connected. In this way, when the first and third color toners and the second and fourth color toners 52 and 56 are electrostatically coupled, the electrostatic force between the second and fourth carriers is weakened, and the toners remain coupled. In the state, the second,
It becomes easier to leave the fourth carrier 54, 58. The toner easily separated from the second and fourth carriers 54 and 58 is separated by a centrifugal force generated when the magnetic roller is rotated and is removed by a removing means (not shown).

Now, in order to perform multicolor recording by the recording apparatus having such a configuration, first, the first photosensitive drum 31 rotating in the arrow direction is used.
After the upper part is uniformly charged to the initial charging potential level by the initial charging device 33, the exposure is performed on the first photosensitive drum 31 via the optical path switching device 48 whose exposure optical path is switched to the (a) side. Part 49
To form a latent image corresponding to the first color information, and the latent image is subsequently developed by the first developing section 34 to form a first toner visible image (yellow).

Next, the first photosensitive drum 31 is rotated once to make the potential of the first toner visible image (yellow) portion substantially equal to the background potential of the first photosensitive drum 31 by the initial charger 33. Recharge.

Subsequently, a latent image corresponding to the second color information is formed by the exposure section 49 on the first photosensitive drum 31 during the next one rotation, and the latent image is continuously developed by the second developing section 35. To form a second toner visible image (magenta),
The color visible image is collectively transferred to the recording paper 50 at the transfer unit 36.

On the other hand, on the second photosensitive drum 32, the first photosensitive drum 31
After the image forming timing is shifted from the side, the initial charging device 40 uniformly charges to the initial charging potential level, and then the optical path switching device 48 is switched to the (b) side and the exposure unit 49 performs the third charging.
To form a latent image corresponding to the color information of the
The third toner visible image (cyan) is developed by the developing unit 41.
To form.

Next, the second photosensitive drum 32 is rotated once to make the potential of the third toner visible image (cyan) portion substantially equal to the background potential of the second photosensitive drum 32 by the initial charger 40. Recharge.

Subsequently, a latent image corresponding to the fourth color information is formed by the exposure section 49 on the second photosensitive drum 32 during the next one rotation, and the latent image is continuously developed by the fourth developing section 42. To form a fourth toner visible image (black),
A color visible image is collectively and multiple-transferred by the transfer unit 43 onto the same recording paper 50 surface on which the first toner visible image (cyan) and the second toner visible image (magenta) have already been transferred.

After that, the multicolor toner image transferred onto the recording paper 50 is subjected to, for example, heat fixing in the fixing unit 47, whereby permanent multicolor recording without color mixture is obtained.

The toner remaining on the surfaces of the first and second photosensitive drums 31 and 32 after the transfer step is destaticized by AC destaticizers 37 and 44, and cleaned and removed by cleaners 38 and 45. Optical charge eliminator 39,46 for all charges on the surface of drum 31, 32
The static electricity is erased by and the next recording cycle starts.

The second development and the fourth development during the recording process in this apparatus
In developing, in order to prevent destruction of the visible images of the first and third toners already formed on the first and second photosensitive drums 31, 32, the second,
The particle size of the fourth carrier 53, 58 is set to the particle size of the toner (10 to 20 μm).
m), and micro-development in which the size is reduced to 5 to 100 μm, or a soft-touch development method such as non-contact development in which an alternating bias voltage is applied to each developing section to cause color toner to fly out of the developer and develop. Applied.

FIG. 3 shows a time chart when multicolor recording is performed by the multicolor recording apparatus of the present invention. When forming pattern latent images of different colors of the information image to be recorded, exposure is performed by a latent image forming signal. By controlling the section 49, the optical path switch 48, which interposes the first latent image P1 to the fourth latent image P4 in the exposure optical path for each page of the recording paper 50, is alternately switched between the state (a) and the state (b). It is formed by switching over the first and second photosensitive drums 31, 32.

The first color toner image and the second color toner image formed on the first photosensitive drum 31 are the third color toner image and the fourth color toner image formed on the second photosensitive drum 32. During the process of transferring, the third color toner image and the fourth color toner image formed on the second photosensitive drum 32 are collectively transferred to the recording paper 50 by the transfer unit 36, and the next recording process is performed. During the step of forming the first color toner image and the second color toner image on the first photosensitive drum 31 in step 1, the transfer unit 43 transfers the first color toner image and the second color toner image. Identical recording paper 50
Multi-color recording is performed at high speed because multiple transfer is performed collectively on the surface.

〔The invention's effect〕

As is clear from the above description, according to the multicolor recording apparatus of the present invention, since the main photosensitive drums are arranged in a plurality and the exposure system is also used, the apparatus cost can be significantly reduced. By arranging a plurality of developing units separately on each photosensitive drum, it is possible to reduce the number of developing units arranged on the photosensitive drum together with the developing unit.
As a result, the number of toners and carriers that need to be arranged in a series of triboelectrification series is reduced, so that the toners and carriers can be easily procured or manufactured, and a practically excellent effect can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an embodiment of a multicolor recording apparatus according to the present invention, and FIG. 2 is an embodiment of a triboelectrification series of toner and carrier used in each developing section of the recording apparatus of the present invention. FIG. 3 is a time chart showing an embodiment of a recording process of the recording apparatus of the present invention, FIG. 4 is a schematic configuration diagram for explaining a conventional multicolor recording apparatus, and FIG. FIG. 6 is a diagram showing a triboelectric charging series of toner and carrier used in each developing unit of the recording apparatus. In the figure, 31 and 32 are first and second photosensitive drums, 33 and 40 are initial chargers, 34, 35, 41 and 42 are first to fourth developing sections, 36 and 43 are transfer sections,
37 and 44 are AC static eliminators, 38 and 45 are cleaners, 39 and 46 are optical static eliminators, 47 is a fixing unit, 48 is an exposure optical path switching unit, 49 is a latent image forming exposure unit, 50 is recording paper, 51, 52, 55, 56 are toners of the first to fourth colors, 53, 54, 57, 58 are the first to fourth carriers, P1 to P4
Indicate the first to fourth latent images, respectively.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuhiko Sato 1015 Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture, Fujitsu Limited (72) Inventor Junzo, Nakajima 1015, Kamikodanaka, Nakahara-ku, Kanagawa Prefecture, Fujitsu Limited ( 56) References JP-A-59-30561 (JP, A) JP-A-49-91233 (JP, A) JP-A-59-121357 (JP, A)

Claims (1)

[Claims] 1. At least two image carriers, one of which has a plurality of developing units, and toners and carriers used in the plurality of developing units are arranged such that triboelectrification series are alternately arranged. , And make the color of each toner different,
An image of a plurality of colors is formed on the image carrier by the plurality of developing units, and then transferred in a batch. The other image carrier has a plurality of developing units, and the toner and carrier used in the plurality of developing units are Select so that the triboelectrification series are arranged alternately, and make the color of each toner different,
An image of a plurality of colors is formed on the image carrier by the plurality of developing units, and then transferred so as to overlap with an image to be transferred by the one image carrier, and a switching device is provided to an exposure optical path for these at least two image carriers. A multicolor recording apparatus in which a single latent image forming exposure unit is arranged via the above, wherein the arrangement of the triboelectric charging series is independently set for each image carrier.