JPH0760279B2 - Multicolor recorder - Google Patents

Description

The present invention relates to a multicolor recording apparatus using an electrophotographic recording method, an electrostatic recording method, or the like, and more particularly, the number of colors of toner supplied from a developing unit is larger. The present invention relates to an apparatus configuration for performing high-resolution multicolor recording by color at high speed.

In recent years, with the diversification of information, colorization of recorded information is required, and electrophotographic recording and electrostatic recording are no exception, and various apparatuses and methods for multicolor recording have been proposed.

In the electrophotographic recording method and the electrostatic recording method, information such as characters is expressed and recorded by a combination of a plurality of pixels. That is, one character is M ×, in which M pixels are arranged in the horizontal direction and N pixels are arranged in the vertical direction.
It is represented by a N dot matrix.

In the electrophotographic recording system, an exposure system using laser light is used as a latent image forming means, and one dot of this laser light corresponds to one pixel.

In order to perform color recording of an image by such an electrophotographic recording method, in principle, after forming a latent image corresponding to a first color on a latent image forming medium such as a photosensitive drum, the latent image is first recorded. The toner image is obtained by developing with the toner of the color. Such an image forming process is sequentially repeated as many times as necessary for the number of colors to obtain a multicolor toner image, and high resolution and high speed recording are required.

[Conventional technology]

The above-mentioned multi-color recording apparatus based on, for example, an electrophotographic recording method is actually roughly classified into the following four methods.

That is, in the first method, one latent image forming unit and a plurality of developing units having different toner colors are provided around the photosensitive drum which serves as a latent image forming medium, and the photosensitive drum is rotated once during one rotation. A toner image of one color is formed on a photosensitive drum, the photosensitive drum is rotated a plurality of times to form a multicolor toner image, and then these multicolor toner images are collectively transferred to a recording sheet. is there.

In the second method, one latent image forming unit and a plurality of developing units having different toner colors are arranged around the photosensitive drum serving as a latent image forming medium, and the photosensitive drum is rotated once during one rotation. A toner image of one color is formed on a rotating drum, the toner image is transferred onto a recording sheet, and the photosensitive drum is rotated a plurality of times to transfer toner images of different colors onto the recording sheet in order to record. A multicolor toner image is obtained on paper.

Further, in the third method, the latent image forming means and the developing means are arranged around the photosensitive drum, which is a latent image forming medium, as many as the number of colors used for recording, and a multi-color image is formed during one rotation of the photosensitive drum. A toner image is formed on the photosensitive drum, and the multicolor toner images are collectively transferred onto a recording sheet while the toner image is rotated.

Further, in the fourth method, a plurality of latent image forming means and a developing means are arranged around a photosensitive drum which is a latent image forming medium, and a plurality of dots corresponding to different colors are arranged to form one pixel. While the photosensitive drum makes one rotation, latent image formation and development corresponding to each color are repeated to form a multicolor toner image in which one pixel is composed of a plurality of dots on the photosensitive drum. The image is collectively transferred onto a recording sheet.

[Problems to be solved by the invention]

However, in the first method and the second method, since multicolor recording is performed on one recording sheet by rotating the photosensitive drum a plurality of times, it requires a long time for recording, and high speed recording is possible. It is difficult to record.

Particularly in the second method, since the transfer is repeated a plurality of times on one sheet of recording paper, a color shift between toner images is likely to occur, which requires high accuracy in the alignment of the recording paper.
It has the drawback of requiring a highly accurate and expensive transfer mechanism.

On the other hand, in the third method, since the same number of latent image forming means and developing means as the number of colors used for recording must be arranged along the rotation direction of the photoconductor, the apparatus structure becomes large. For example, after the first toner image formation, the second toner image is formed.
When forming the toner image of No. 2, there is a problem that the extra second toner is replaced with a part of the first toner in the already formed first toner image to cause color mixing.

In the fourth method, a plurality of color dots are used to
Since the pixels are formed, there is a drawback that the resolution of the recorded image is lowered. In order to increase this resolution, the laser beam used as the latent image means must be made a thin beam which is a fraction of that of the conventional one, which is technically difficult.

[Means for solving problems]

The present invention provides high-resolution multicolor recording that solves the above problems.
The present invention provides a multicolor recording device capable of high-speed operation, and a means thereof is a multicolor recording device that develops a latent image formed on a latent image forming medium by attaching toners of different colors to each other. A plurality of developing units having different toner colors, at least one charging unit, and at least one exposing unit during a process of moving the latent image forming medium in one recording cycle of the latent image forming medium, The exposing means selectively re-exposes on the latent image forming medium including the areas already developed by the toner, thereby depositing different color toners on the areas already developed by the toner to form a multicolor image. The multi-color recording method according to the present invention is configured so that a control device for recording is connected.

[Action]

That is, in the present invention, the latent image formation corresponding to each color, the development, and the high-potential charging on the medium surface are sequentially repeated a plurality of times on the photosensitive drum, which is the latent image forming medium, while the photosensitive drum makes one revolution. By doing so, a multi-color toner image having a larger number of original toner colors than the toner image overlapping area is formed on the latent image forming medium.

Further, by transferring the multi-color toner image to the recording paper all at once by the transfer means during the rotation, there is no color misregistration,
It becomes possible to record at high speed a high-resolution multicolor image in which one pixel is composed of color dots in which toner images such as single color, two colors, three colors ...

〔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 which 1 is a photosensitive drum, 21 to 23 are chargers, and 31 is a charger.
˜33 is an exposure part, 41˜43 is a development part, 5 is a transfer corotron 51
Is a charge eliminating corotron, 7 is a brush cleaner, 8 is a charge eliminating lamp, and 9 is a recording sheet.

The photosensitive drum 1 as a latent image forming medium has a photosensitive layer on its surface and rotates at a constant speed in the direction of the arrow. Charger
21 to 23 are for uniformly supplying electric charges to the surface of the photosensitive layer. The exposure units 31 to 33 form latent images, and irradiate the photosensitive layer on the photosensitive drum 1 with laser light according to information such as characters to be recorded. One dot of the laser light from each of the exposure units 31 to 33 constitutes one pixel of information such as characters.

The developing units 41 to 43 form a toner image by reversal development on the latent image on the photosensitive layer thus formed.For example, the developing unit 41 forms a yellow toner image and the developing unit 42 forms a magenta image. A toner image is formed, and the developing unit 43 forms a cyan toner image.

That is, a toner image of a certain color is formed on the photosensitive layer by the set of the charger, the exposing section and the developing section.
Individually installed.

The transfer portion 5 transfers the toner image formed on the photosensitive layer to the recording paper 9
The transfer corotron 51 is provided for that purpose. Further, the charge-removing corotron 6 electrostatically removes the residual toner not transferred at the transfer portion 5 and the electric charge of the photosensitive layer, and the brush cleaner 7 removes the residual toner not transferred at the transfer portion 5 from the surface of the photosensitive layer. The static elimination lamp 8 optically removes the electric charge of the photosensitive layer.

The photosensitive drum 1 from which the electric charge and the residual toner have been removed by the above-described charge removing and toner removing mechanism is again subjected to the toner image forming process.

FIG. 2 is a block diagram showing the control means of the exposure units 31 to 33, wherein 200 is a color decoding circuit, 300 is an exposure position correction circuit, 201 to 203 are pattern memories, 204 to 206 are scan control units, and 207 to 207. Reference numeral 209 is a drive circuit, 220 to 222 are clock circuits, 213 to 215 are laser diodes, 216 to 218 are photodetectors, and 311 to 313 are rotating polygon mirrors.

Then, the color decoding circuit 200 uses the dot pattern signal Pd corresponding to the information to be recorded and the color designating signal Cd for designating the color of the signal to be recorded in the pattern memory 20.
Supply a dot pattern to 1-203.

For example, when the color designation signal Cd is yellow, the pattern memory 20
Dot pattern of '1' to 1 and pattern memory 202 to 203
Is supplied with a dot pattern of '0'. Therefore, in this embodiment, a total of eight colors including white can be designated.

Further, the clock control circuits 220 to 222 correspond to the corresponding photodetectors 216.
With the signal input from ~ 218 as a trigger, a print clock corresponding to one dot (one pixel) is created. Pattern memory
When the dot pattern from 201 to 203 is '1', the drive circuit
207 to 209 cause the laser diodes 213 to 215 to emit light, and does not emit when the dot pattern is "0".

Laser beams from the laser diodes 213 to 215 are deflected by rotating polygon mirrors 311 to 313 via an optical system, and the photosensitive drum 1 is scanned in a predetermined scanning direction. At the start of this scanning, the laser light is detected by the photodetectors 216-218.

Next, an embodiment of the multicolor recording method according to the present invention will be described with reference to the potential distribution diagrams of FIGS. 3 to 11 and the time chart of FIG.

When the color of the image to be recorded is a mixed color of yellow, magenta, and cyan, the dot patterns of all "1" are recorded in the pattern memories 201 to 203.

On the other hand, the photosensitive layer made of Se, SeTe, etc. of the photosensitive drum ₁ is initially charged by the charger 21 to the potential Vs _{1 as} shown in FIG.

Next, as the rotary polygon mirror 311 rotates, the clock control circuit 220
The start signal shown in FIG. 12 (a) is input to. After a lapse of a predetermined time t, as shown in FIG.
The dot pattern '1' from the pattern memory 201 becomes the first by the clock signal corresponding to the dots output from 220.
As shown in FIG. 2 (c), the laser diode 213 of the exposure unit 31 emits light by being input to the drive circuit 207, and the exposure corresponding to yellow is performed so that the potential is substantially equal as shown in FIG.
The dot latent image DY attenuated to OV is formed.

Next, the dot latent image DY is subjected to reversal development by the yellow developing device 41 located in the rotation direction of the photosensitive drum 1 to form a toner image TY corresponding to the yellow dot on the photosensitive drum 1 as shown in FIG. Form.

Thereafter, the entire surface potential of the photosensitive layer is recharged by the charger 22 to a potential Vs ₂ higher than the initial charging potential Vs _{1 as} shown in FIG. At this time, the portion where the toner image TY corresponding to the yellow dot is formed has a potential close to the recharge potential Vs ₂ due to the rise in the potential of the photosensitive layer immediately below.

Next, on the photosensitive layer, exposure corresponding to magenta is performed by the emission of the laser diode 214 of the exposure unit 32 by the signal input shown in FIG. 12 (d), and the potential becomes approximately OV as shown in FIG. A latent image DM in which the potential of the toner image TY portion is selectively attenuated is formed on the attenuated dot latent image DM and the area where the yellow dots have already been developed.

The exposure at this time is delayed and controlled by the exposure position correction circuit 300 at the time when the toner image TY corresponding to the already formed yellow dot reaches the exposure unit 32.

Next, the dot latent image DM is subjected to reversal development by the magenta developing device 42 located in the rotation direction of the photosensitive drum 1, and a toner image TM corresponding to magenta dots is formed on the photosensitive drum 1 as shown in FIG. Then, a toner image in which the toner images TM corresponding to magenta dots are vertically superimposed is formed on the toner image TY corresponding to yellow dots.

After that, the entire surface potential of the photosensitive layer on the photosensitive drum 1 is recharged by the charger 23 to a potential Vs ₃ which is higher than the potential Vs _{2 as} shown in FIG.

At this time, the toner image TY corresponding to the yellow dot already formed and the toner image TY corresponding to the yellow dot are formed.
In addition, the potential of the portion where the toner images TM corresponding to magenta dots are vertically superimposed becomes close to the recharge potential Vs ₃ due to the increase in the potential of the photosensitive layer immediately below.

Subsequently, the exposure unit by the signal input shown in FIG. 12 (e) which is delay-controlled by the exposure position correction circuit 300 on the photosensitive layer.
The exposure corresponding to cyan is performed by the emission of the laser diode 215 of 33, and the dot latent image DC in which the electric potential is attenuated to approximately OV and the area where the yellow dots have already been developed are shown in FIG. Toner image TM portion, toner image TY corresponding to the yellow dot is already superposed with toner corresponding to the magenta dot on the toner image TY portion, the area where the magenta dot has already been developed. A latent image in which the potential of the toner image TM part is attenuated selectively on the developed area
Form DC.

Next, the dot latent image DC is subjected to reversal development by the cyan developing device 43 located in the rotation direction of the photosensitive drum 1 to perform the reverse development.
As shown in FIG. 11 above, a toner image TC corresponding to a cyan dot and a toner image TC corresponding to a cyan dot on a toner image TM corresponding to a magenta dot are a toner image in which the toner image TC is vertically superimposed, and a yellow dot. A toner image TM corresponding to a magenta dot and a toner image TC corresponding to a cyan dot are vertically superimposed on the toner image TY corresponding to the above to form a toner image.

As described above, while the photosensitive drum 1 makes one rotation, yellow, magenta, cyan and red by mixing yellow and magenta, edges by mixing yellow and cyan, and blue by mixing magenta and cyan are formed on the photosensitive layer of the photosensitive drum 1. 7 consisting of black with a mixture of yellow, yellow, magenta and cyan
A color dot toner image is obtained, and the toner image is electrostatically transferred collectively to the recording paper 9 at the transfer portion 5 during its rotation, and is fixed at a fixing portion (not shown) for permanent multicolor recording.

Therefore, there is no color shift compared with the conventional method, and one pixel is composed of one color dot or a dot in which a plurality of colors are overlapped, resulting in high resolution and high-speed multicolor recording. it can.

In the developing units 42 and 43, the toner image TY corresponding to the yellow dots already formed on the photosensitive layer of the photosensitive drum 1 or the toner image TM corresponding to the magenta dots is used.
It is necessary to develop and form a toner image corresponding to dots of other colors on it without destroying it.

For this reason, the soft developing method in which the particle size of the carrier of the developer used in the developing sections 42 and 43 is 5 to 100 μm, which is the same as that of the toner, or an AC bias with a frequency of about 1 KHz between them is applied. It is desirable to use a non-contact developing method in which a toner image is formed on the latent image on the photosensitive drum 1 by applying the toner so that the toner flies.

Further, the reason why the surface potential of the photosensitive layer is made high every time the recharging performed after the initial charging is repeated is to obtain sufficient latent image strength even in the already formed toner image portion. Is also set proportionally higher.

Furthermore, in the above-mentioned embodiment, when a toner image portion already formed on the photosensitive layer is exposed to form a latent image on the photosensitive layer immediately below, when a dye is used as a colorant for the color toner, a specific wavelength range of Light is absorbed, but light in other wavelength regions is attenuated but transmitted.

That is, light having a wavelength longer than approximately 500 nm is transmitted to the layer of the yellow toner image. Also, light having a wavelength longer than about 600 nm is transmitted to the layer of the magenta toner image. Also, for the layer portion where the yellow and magenta toner images overlap, 600 nm is the same as for the magenta toner image.
Since light of the above long wavelength is transmitted, as a light source for exposure, a He--Ne gas laser with an oscillation wavelength of 633 nm or a semiconductor laser with an oscillation wavelength of 740 to 780 nm is used to form various color toner image layers. Through which the latent image can be formed by giving sufficient exposure on the photosensitive layer.

13 and 14 show another embodiment according to the present invention. In this embodiment, the photosensitive layer immediately below the toner image portion already formed is easily exposed to form a latent image. To this end, a transparent base material 65 is used as a base material of the photosensitive drum as shown in a partially enlarged sectional view of FIG. 14, a transparent electrode 66 is provided on the upper surface thereof, and a photosensitive layer 67 made of Se, SeTe, etc. is further laminated. The photosensitive drum 61 having the above configuration is applied.

Therefore, the exposure of the photosensitive layer 67 is performed by exposing the transparent base material 65 and the transparent electrode 66 from the inside of the drum 61 by the exposure means 62, 63, 64.

According to such a method, even if the layer of the color toner image becomes thick, it is not necessary to select a long-wavelength exposure light source with an oscillation wavelength of 600 nm or more in consideration of the attenuation of the exposure amount, and it is possible to control the exposure light amount. Will also be easier. Therefore, it is possible to easily give the required exposure to the photosensitive layer 67 directly below the toner image portion.

As the illustrated exposure means 62, 63, 64, a configuration in which a semiconductor laser, an optical system, and a rotary polygon mirror are combined, or a small exposure device including an LED array, a liquid crystal shutter array, or the like can be used.

〔The invention's effect〕

As is clear from the above description, according to the multicolor recording apparatus of the present invention, one pixel on the latent image forming medium is a single layer color toner image and a single color toner image on the latent image forming medium during one rotation. A plurality of different color toner images are formed in a mixed color toner image that is vertically superimposed, and electrostatically transferred collectively to the recording paper during the rotation, so there is no color misregistration and there are more than the number of toner colors. It is possible to perform high-resolution multicolor recording by color at high speed.

Therefore, it is extremely advantageous when applied to multicolor recording such as this type of electrophotographic recording system or electrostatic recording system.

[Brief description of drawings]

FIG. 1 is a schematic block diagram showing an embodiment of a multicolor recording apparatus according to the present invention, FIG. 2 is a block diagram showing a control circuit of an exposure unit, and FIGS. 3 to 11 are multicolor recording of the present invention. FIG. 12 is a potential distribution diagram showing changes in the potential of the photosensitive layer in each recording step for explaining one example of the recording method by the apparatus, FIG. 12 is a time chart showing signal waveforms from main parts in the circuit of FIG. FIG. 13 is a schematic device configuration diagram for explaining another embodiment of the multicolor recording device according to the present invention, and FIG. 14 is a partially enlarged cross-sectional view of the device configuration of FIG. In the figure, 1,61 is a photosensitive drum, 21-23 are chargers, 31-33 are exposure parts, 41-43 are development parts, 5 is a transfer part, 200 is a color decoding circuit, 300 is an exposure position correction circuit, 201 Reference numeral 203 to a pattern memory, 204 to 206 a scan control unit, 207 to 209 a drive circuit, 220 to 222 a clock circuit, 213 to 215 a laser diode, 216 to 218 a photodetector, and 311 to 313 a rotary polygon mirror. ,
62, 63 and 64 are exposure means, 65 is a transparent substrate, 66 is a transparent electrode,
67 indicates a photosensitive layer, respectively.

 ─────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-58-163961 (JP, A) JP-A-59-191072 (JP, A) JP-A-58-116553 (JP, A) JP-A-58- 80653 (JP, A) JP-A-60-87361 (JP, A)

Claims (1)

[Claims] 1. A multicolor recording apparatus for developing a latent image formed on a latent image forming medium by attaching toners of different colors to each other, wherein the latent image forming medium during one recording cycle of the latent image forming medium. During the process of moving the toner, the developing device has a plurality of developing parts having different toner colors, at least one charging device, and at least one exposing device, and the exposing device includes the latent image formation including a region already developed by the toner. It is characterized in that a control device is connected to selectively re-expose the medium, thereby depositing different color toners on the areas already developed by the toners and performing multicolor recording. Multicolor recording device.