JPH0441824B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a multicolor recording device using an electrophotographic recording method, and in particular to a device that can perform clear multicolor recording without color mixture over a long period of time at high speed. It's about structure.

In recent years, with the diversification of information, the color of recorded information such as characters, symbols, images, etc. is changed as necessary, and color recording is performed in which characters, symbols, images, etc. of different colors are mixed on the same recording paper. is required, and various devices or methods related to multicolor recording have been proposed.

In general, in electrophotographic recording, a photosensitive drum is uniformly charged, and an electrostatic latent image is formed by exposing the photosensitive drum to light corresponding to the information image to be recorded, and then the latent image is transferred to a developing device. The toner is developed to form a visible image using toner, and this visible image is transferred onto recording paper for recording.

Therefore, multiple image forming sections including latent image forming means and developing units are provided around the photosensitive drum, and each image forming section sequentially forms a visible image on the surface of the photosensitive drum using toner of different colors. By forming a visible image and transferring the visible image onto recording paper, a multicolor recording can be obtained.

In a device that performs multicolor recording using toners of different colors, the toner in the developer used in the previous development step is mixed into the developer in the next development step, and this There is a problem in that as the amount of accumulated mixed toner increases, color mixing tends to occur in the toner visible image, and there is a demand for solving this problem.

[Conventional technology]

As a conventional device that performs multicolor recording at high speed using an electrophotographic recording method, a device or method that performs multicolor recording during one rotation of a photosensitive drum has already been proposed by the present applicant in Japanese Patent Laid-Open No. 52-106743, Kaisho 58-116553
proposed by.

The conventional multicolor recording device using the electrophotographic recording method described above is shown in FIG. 4, which is a schematic diagram of a two-color recording device, and in FIGS. As shown in the level diagram, first, an initial charger 2 is placed on the surface of a photosensitive drum made of a photosensitive layer such as selenium (Se).
As shown in Figure 5, the initial charging potential level is
Charge Vs uniformly over the entire surface.

Next, the first exposure section 3 performs negative exposure corresponding to the first color information on the surface of the photosensitive drum 1,
As shown in Figure 6, the charged potential of the exposed area is approximately
A first latent image 21 attenuated to 0V is formed. Thereafter, the first latent image 21 is developed using a two-component magnetic developer containing a first color toner and a carrier.
Magnetic brush reversal development is performed by the developing device 4 to form a first toner visible image 22 as shown in FIG.

Next, the first toner visible image 2 is charged by the recharging device 5.
The second part is recharged so that the potential Vt becomes approximately the same potential as the background potential Vs on the photosensitive drum 1, as shown in FIG. This process is based on the already formed first
This is to prevent toner from adhering to the toner visible image 22 during the next development.

Next, a second
The second exposure unit 6 performs negative exposure corresponding to the color information of , to form a second latent image 23 in which the charged potential of the exposed portion is attenuated to approximately 0V as shown in FIG. Thereafter, the second latent image 23 is subjected to magnetic brush reversal development using a second developing device 7 using a two-component magnetic developer containing a second color toner and a carrier, as shown in FIG. A second toner visible image 24 is formed.

The first and second toner visible images 22 and 24 thus formed on the surface of the photosensitive drum 1 are transferred to a transfer device 8.
The images are transferred all at once onto the recording paper 13 by the image forming apparatus 1, and further fixed by the fixing section 9 to record information in two colors.

On the other hand, the toner remaining on the surface of the photosensitive drum 1 is neutralized by the AC static eliminator 10, and the toner remaining on the surface of the photosensitive drum 1 is removed by the cleaner 1.
The photosensitive drum 1 is cleaned and removed in step 1, and then all charges on the surface of the photosensitive drum 1 are removed and erased by an optical charge eliminator 12, and the next recording cycle begins.

In addition, in the recording apparatus, the second developing device 7 is used so that the first toner visible image 22 formed in the previous first developing step is not destroyed in the next second developing step.
In this case, a two-component magnetic developer using a microcarrier with a carrier particle size of 5 to 100 μm mixed with the second color toner is applied, or an alternating current bias voltage is applied to the developing device 7. Therefore, a soft-touch development method such as non-contact development is used in which the toner of the second color is ejected from the developer.

Further, in order to prevent color mixing of the second toner visible image 24 caused by the toner of the first color mixed in and accumulated in the second developing device 7, the mixed toner of the first color is removed from the second developing device 7. The applicant has already proposed a method of separation from the developer in JP-A No. 58-1057134.

That is, the above separation method separates the first and second color toners 31 and 32 in the first developer and the second developer.
and the first carrier 3 mixed with these, respectively.
The frictional charging series of the 3rd and 2nd carriers 34 is the 11th
This is done by selecting as shown in the figure.

The first and second color toners 31 and 32 are charged to a positive polarity by frictional charging with a first carrier 33 and a second carrier 34, respectively. Further, when the first color toner 31 enters the second developing device 7, its polarity is reversed to negative polarity or becomes approximately zero due to frictional charging with the second developer.

Further, the first color toner 31 of negative polarity is electrostatically combined with the second color toner 32 of positive polarity, and the apparent charge amount becomes approximately 0, and as a result, the second carrier 34 and The bonding force of the first and second color toners 31 and 32 may remain electrostatically bonded to each other, or the first color toner 31 may have a charge amount of approximately 0.
The toner 31 of the first color is scattered and separated from the developing roller in the second developing device 7 by centrifugal force, and the mixed first color toner 31 is not accumulated in the second developing device 7, so that the above-mentioned record remains for a long period of time. This makes it possible to stably record two-color information without color mixing even after repeated operations.

As a configuration for recording more color information in accordance with such a two-color recording configuration, for example, as shown in FIG.
2, a first exposure section 43 and a development section 44, a recharger 45, a second exposure section 46 and a development section 47, a recharger 48, a third exposure section 49 and a development section 50,
Furthermore, a transfer device 54, a fixing device 55, an AC static eliminator 56,
A cleaner 57 and an optical static eliminator 58 are arranged in this order, and the toner colors of the developer used in each of the developing devices 44, 47, and 50 are changed to cyan, magenta, and yellow, and a recording operation is performed according to the two-color recording process. By doing so, it is possible to realize good multicolor recording without color mixture.

[Problem that the invention seeks to solve]

Incidentally, in the multicolor recording apparatus as described above, black character information is generally recorded in many cases, but in this case, recording is performed by mixing visible toner images of the three colors.

However, even if three color toners are mixed, complete black cannot be obtained, so the third developing section 50 in the recording apparatus is provided at a later stage, and further includes a recharging device 51, a fourth exposing section 52, and black toner. Attempts have been made to arrange a developing section 53 using a developer.

However, adding an image forming function unit that records black character information not only makes the already complicated device configuration even more complicated, but also
Toners 61 and 62 of the first to fourth colors in the so-called first to fourth developers are used to separate and remove different color toners mixed into the developing devices 50 and 52 after the developing section 47 to prevent color mixing. , 63 and 64, and the first to fourth carriers 65, which are mixed therewith, respectively.
66, 67, and 68 must be selected to form the triboelectrification series shown in FIG. 13, and it has been extremely difficult to procure and manufacture toners and carriers having such a triboelectrification series.

[Means for solving problems]

The above-mentioned problem is that the first charger, which has one charger and one latent image forming section, two developing sections using toners of different colors and triboelectric charging series, a transfer section and a cleaning section, are arranged around each of the first and second parts. photosensitive drum,
A second photosensitive drum is arranged in parallel in the recording paper traveling direction, and the latent image forming section and the other developing section are placed on the photosensitive drum while the first photosensitive drum rotates twice. A developing section sequentially forms a visible image using first and second color toners corresponding to the first and second color portions of the information image to be recorded, and the visible image is recorded by a transfer section. While the visible image is transferred all at once onto the paper, the latent image forming section, one of the developing sections and Visible images formed by third and fourth color toners corresponding to the third and fourth color portions of the information image to be recorded are formed sequentially by the same latent image forming section and the other developing section. This problem is solved by the multicolor recording apparatus according to the present invention, which is configured to perform multicolor recording by performing batch transfer in the transfer section.

[Effect]

That is, two photosensitive drums are used, and four developing sections using developers containing toners of cyan, magenta, yellow, and black colors are arranged around the two photosensitive drums, along with one latent image forming section each. , two of each are arranged, and while one photosensitive drum rotates twice, one latent image forming section and two developing sections collectively transfer visible images formed by toner of two colors sequentially onto recording paper. , while the other photosensitive drum rotates twice, one latent image forming section and two developing sections sequentially form a visible image of two colors of toner on the recording paper. The configuration is such that multi-color recording is performed by transferring, and each color toner and carrier used in the two developing sections arranged on each photosensitive drum have a frictional charging series, so that the toner of the subsequent stage mixed into the developing section of the previous stage is By reversing the polarity of toner or attenuating the amount of charged charge and separating and removing the toner due to the difference in the order in the triboelectrification series, color mixing is prevented. It becomes possible to perform multicolor recording stably.

〔Example〕

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

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

In order to avoid complication of the structure, the device configuration of the present invention includes two photosensitive drums each having a photosensitive layer made of selenium (Se) or SeTe, etc., as shown in the figure.
That is, the first and second photosensitive drums 71 and 72 are arranged in parallel in the running direction of the recording paper 90.

Further, around the first photosensitive drum 71, an initial charger 73, a first latent image forming exposure section 74 consisting of a He-Ne gas laser, a semiconductor laser, an LED array, etc., a first developing section 75, and A second developing section 76, a transfer section 77, an AC static eliminator 78, a cleaner 79, and an optical static eliminator 80 are arranged in this order,
Further, around the second photosensitive drum 72, an initial charger 81, a second latent image forming exposure section 82 consisting of a He-Ne gas laser, a semiconductor laser, an LED array, etc., a third developing section 83, and The fourth developing section 84, a transfer section 85, an AC static eliminator 86, a cleaner 87, and an optical static eliminator 88 are arranged in this order.

Furthermore, each of the developers used in the first to fourth developing units 75 to 84 contains toner in the order of cyan, magenta, yellow, and black, and in addition, the carrier and toner of each developer is 2 placed on each of the photosensitive drums 71 and 72.
Toners 101 and 102 of the first and second colors and the first and second carriers used in the two developing sections, that is, the first developing section 75, the second developing section 76, the third developing section 83, and the fourth developing section 84. 103, 104 and the third,
Fourth color toner 105, 106 and third and fourth color toners
The carriers 107 and 108 are separately selected to form independent triboelectric charging series as shown in FIG. The toners 101 and 105 are used as a second developer or a fourth developer that has a different rank on the triboelectric charging series.
When the polarity is reversed due to frictional charging with the developer, the amount of charge is attenuated and separated and removed.

Now, in order to perform multicolor recording using the recording apparatus having such a configuration, first, the first photosensitive drum 71 is uniformly charged to an initial charging potential level by the initial charger 73, and then said first during rotation
A latent image corresponding to first color information is formed on the photosensitive drum 71 by the first exposing section 74, and this latent image is subsequently developed by the first developing section 75 to form a first toner visible image ( cyan).

Next, the potential of the first toner visible image (cyan) formed on the first photosensitive drum 71 is reset by the initial charger 73 so that it becomes approximately the same potential as the background potential of the first photosensitive drum 71. Apply electrical charge.

Subsequently, the first exposure section 74 forms a latent image corresponding to the second color information on the first photosensitive drum 71 during the next rotation, and the latent image is subsequently subjected to a second development process. After developing to form a second toner visible image (magenta) in a transfer section 76, these two-color visible images are transferred at once onto a recording sheet 90 in a transfer section 77.

On the other hand, on the second photosensitive drum 72, the image forming timing is shifted from that on the first photosensitive drum 71 side.
First, after uniformly charging to the initial charging potential level by the initial charger 81, a latent image corresponding to third color information is formed in the second exposure section 82, and this latent image is subsequently subjected to a third development. 83 to form a third visible toner image (yellow).

Next, the potential of the third toner visible image (yellow) portion formed on the second photosensitive drum 72 is reactivated by the initial charger 81 so that it becomes approximately the same potential as the background potential of the second photosensitive drum 72. Apply electrical charge.

Subsequently, the second exposure section 82 forms a latent image corresponding to the fourth color information on the second photosensitive drum 72 during the next one rotation, and the latent image is subsequently applied to the fourth color information.
After developing by the developing section 84 to form a fourth toner visible image (black), these two color visible images are already combined with the first toner visible image (cyan) and the second toner visible image (cyan).
The toner visible image (magenta) is transferred all at once onto the same recording paper 90 in the transfer section 85.

Thereafter, the multicolor toner image transferred onto the recording paper 90 is thermally fixed, for example, in the fixing section 89, thereby obtaining permanent multicolor recording without color mixture.

Incidentally, the toner remaining on the surfaces of the first and second photosensitive drums 71 and 72 is removed by an AC static eliminator 78 and an AC static eliminator 78, respectively.
The charge is removed by cleaners 79 and 87, and each photosensitive drum 7
All charges on the 1st and 72nd surfaces are eliminated and erased by optical charge removers 80 and 88, and the next recording cycle begins.

Also, for the second development and fourth development during the recording process in this apparatus, the first and second photosensitive drums 71,
In order to prevent destruction of the already formed first and third toner visible images on 72, the second and fourth carriers 1
There are soft-touch development methods such as micro-development in which the particle size of 03,108 is reduced to 5 to 100 μm, or non-contact development in which an AC bias voltage is applied to each development section to cause the toner to fly into the developer. Applicable.

Further, FIG. 3 shows an example of a second developing device and a fourth developing device that perform the second developing and fourth developing described above.

The developing roller 111 is composed of a magnetic roller 112 and a non-magnetic cylindrical sleeve 113, and the developer is transferred to the photosensitive drums 71, 72 by the rotation of the magnetic roller 111 or the rotation of the sleeve 113.
being transported to the side.

In each opening 114, 115 of these developing devices,
When the mixed first and third color toners are separated,
By attaching an air suction collection tool or the like for collecting these toners, it becomes possible to efficiently collect the separated color toners.

〔Effect of the invention〕

As is clear from the above description, according to the multicolor recording device according to the present invention, the main photosensitive drums are configured in two series, and each photosensitive drum has one exposure section for forming a latent image and two developing areas. Since a configuration is adopted in which toner visible images of two colors are continuously formed in each section, and these two-color toner visible images are successively superimposed and transferred onto one sheet of recording paper, The number of image forming functions placed around each photosensitive drum is reduced,
This eliminates the complexity of the device configuration, and provides the advantage that manufacturing, adjustment, maintenance, etc. of the device is facilitated.

In addition, in order to prevent color mixing, the triboelectric charging series of the toner and carrier of each developer may be selected in consideration of the triboelectric charging series of each developer used in the two developing devices of each photosensitive drum unit. It has many excellent practical effects, such as facilitating the procurement and production of toner and carrier for each of these developers.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of a multicolor recording device according to the present invention, and FIG. 2 shows an embodiment of the triboelectric charging system of toner and carrier used in each developing section of the recording device of the present invention. FIG. 3 is a vertical cross-sectional view of a main part showing an embodiment of the developing section of the recording apparatus of the present invention, and FIG.
The figure is a schematic configuration diagram showing a two-color recording device applied to simplify the explanation of the conventional multi-color recording device.
Figures 10 to 10 are diagrams showing potential levels on the photosensitive drum in each process of two-color recording;
The figure shows the triboelectric charging system of toner and carrier used in each developing section for two-color recording. Figure 12 is a schematic configuration diagram showing an example of a conventional multicolor recording device.
This figure is a diagram showing the triboelectric charging series of toner and carrier used in each developing section in the multicolor recording apparatus of FIG. 12. In the figure, 71 and 72 are the first and second photosensitive drums;
3 and 81 are initial chargers, 74 and 82 are first and second chargers.
exposure section, 75, 76, 83, 84 are first to fourth developing sections, 77, 85 are transfer sections, 78, 86 are AC static eliminators, 79, 87 are cleaners, 80, 88 are optical static eliminators, 89 are a fixing unit, 90 a recording paper, 101;
102, 105, 106 are first to fourth color toners; 103, 104, 107, 108 are first to fourth carriers; 111 is a developing roller; 112 is a magnetic roller; 113 is a sleeve; 114, 115 are openings. The parts are shown respectively.

Claims (1)

[Claims] 1. A first photosensitive drum, each of which is provided with one charger, one latent image forming section, two developing sections using toners of different colors and triboelectric charging series, a transfer section, and a cleaning section; A second photosensitive drum is arranged in parallel in the recording paper traveling direction, and the latent image forming section and the other developing section are placed on the photosensitive drum while the first photosensitive drum rotates twice. The first developing section of the information image to be recorded is
A visible image is sequentially formed using toner of a first color and a second color corresponding to a second color portion, and the visible image is transferred all at once onto a recording paper by a transfer section, and the second photosensitive drum is On the photosensitive drum during rotation, the latent image forming section and one developing section and the same latent image forming section and the other developing section correspond to the third and fourth color portions of the information image to be recorded. The visible images of the third and fourth color toners formed sequentially in the transfer section are transferred all at once to the recording paper onto which the first and second color toner visible images have been transferred. A multicolor recording device characterized by recording.