JPS61223856A - Multicolored image forming device - Google Patents

Abstract

PURPOSE:To improve the printing speed of a multicolored image forming device by effectively utilizing its image forming body when a print, whose image size is smaller than the maximum image size, is made so as to make the printing work of the device more efficient, by changing the number of images formed on the image forming body in accordance with the size of the image of one unit. CONSTITUTION:When an original of a size, A-3, is placed on an image reading device, image reading and writing on an image forming body are synchronously performed and, by repeating the synchronous operations, a multicolored toner image can be formed on the image forming body. When the size of an original is A-4, two originals A and B are placed in parallel and multicolored toner images corresponding to the two originals are formed on the image forming body in the same way as in the case of A-3 size original. The two toner images thus formed are transferred to two sheets of paper fed synchronously to each image of the originals A and B and successively discharged. Therefore, plural sheets of prints can be made within the time required for making the print of the maximum image size, if the image size is smaller than the maximum image size.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a multicolor image forming apparatus, and particularly to a multicolor image forming apparatus capable of forming images of a plurality of original documents on an image forming body. It is.

[Background of the invention]

To form a toner image, the copying steps of charging, exposing, developing, and transferring are repeated for each component color, so that toner images of each color are superimposed and transferred onto copy paper.

For example, an electrostatic charge image is formed in each of the steps using separated light of blue, green, red, etc. obtained through a color separation filter, and developed with yellow, magenta, cyan, and if necessary black toner to form a toner image. The toner images for each color are layered and transferred onto recording paper to form a multicolor image.

However, in such a multicolor image forming method, it is necessary to transfer the image to the transfer body each time the phenomenon of each color is completed;
In addition to the increased size of the machine, there are other drawbacks such as the long time it takes to form an image, and the need to ensure positional accuracy due to repeated operations.

Therefore, multiple toner images are superimposed and developed on the same photoreceptor (the toner images are superimposed, and the toners may or may not overlap), and the latent images are developed to form a toner image. Since this is a multicolor image forming apparatus that repeatedly performs the process of overlapping each color toner image on the image forming body to form a toner image of each color on the image forming body, only one transfer process is required, and the multicolor image that solves the above-mentioned drawbacks. There is a formation method, but even with this method, during the subsequent development, the toner image obtained by the previous development may be disturbed, or the toner in the previous developer may be mixed into the latter developer, resulting in the formation of a multicolor image. This may cause problems such as color balance being disturbed.

In order to avoid such adverse effects, the photoreceptor and the developer layer that develops the electrostatic latent image formed on the photoreceptor are made non-contact, and an AC component is superimposed on the DC bias applied to the developing device to remove the developer. A method has been proposed for forming a multicolor image by employing a method of developing by causing the toner inside to fly.

In this method, the developer layer does not rub the toner image formed up to the previous stage, so that image disturbance does not occur.

The principle of this image forming method will be explained below with reference to the flowchart shown in FIG.

FIG. 1 shows changes in the surface potential of the photoreceptor, taking as an example the case where the charging polarity is positive.

PH is the exposed area of the photoreceptor, DA is the unexposed area of the photoreceptor, DU
P indicates an increase in potential caused by the positively charged toner T adhering to the exposed area PH during the first development, and CUP indicates an increase in potential of the exposed area PH caused by the second charging.

The photoreceptor is uniformly charged by a scorotron charger or the like to give a constant positive surface potential E. This surface potential E is lowered to near zero potential at the exposure portion RH by the first image exposure using an exposure source such as a laser, a cathode ray tube, a liquid crystal shutter, or an LED.

Here, by applying a positive bias whose DC component is approximately equal to the surface potential E of the unexposed area to the developing device to perform development, the positively charged toner T in the developing device is transferred to the exposed area PH where the potential is relatively low. , and a first visible image is formed.

In the area where the visible image is formed, the potential increases by an amount of DUP due to the attachment of the positively charged toner T, but the potential further increases by an amount of CUP due to the second charging performed by the charger. As a result, the initial surface potential E is obtained as in the non-exposed area DA.

Next, a second imagewise exposure is performed on the surface of the photoreceptor with a uniform surface potential E to form an electrostatic latent image, and a second visible image is formed through a similar development operation. can get.

By repeating the above process, a multicolor toner image is obtained on the photoreceptor, and this is transferred to recording paper and further fixed by heating or pressurizing, thereby obtaining a multicolor image.

Here, the toner and charge remaining on the photoreceptor are cleaned and prepared for the next multicolor image formation.

Note that in the multicolor image forming method, the second and subsequent charging steps can be omitted.

Instead of omitting such charging, it is also possible to include a static elimination step by repeating charging each time.

Furthermore, the exposure sources used for each image exposure may be the same or different.

In the multicolor image forming method, toner images of four colors, for example, yellow, magenta, cyan, and black, are often formed on a photoreceptor by superimposing them, and this is for the following reason.

　　　　　　　　　　　　　　　　.

A black image should be obtained by overlapping the three primary colors of yellow, magenta, and cyan, but the toners for the three primary colors in practical use do not have the ideal absorption wavelength range, and the toners for the three primary colors do not have the ideal absorption wavelength range. Because it is difficult to accurately align images, it is difficult to reproduce the clear black required for characters, line drawings, etc. using only the three primary colors.

Therefore, as described above, toner images of four colors including black in addition to the three primary colors are superimposed to obtain a multicolor image closer to the original.

In addition, in the multicolor image forming method, a reversal developing method is used as a method for developing a static xi image. Since there is no need to expose the background portion without gaps, a latent image can be relatively easily formed even on a photoreceptor on which a toner image has already been formed.

Further, there are advantages such as less fatigue of the photoreceptor and a longer life. Furthermore, since the second and subsequent charging is performed with the same polarity as the toner, there is no problem with electrostatic transfer.

As a method for forming a latent image for forming a multicolor image, in addition to the method of forming an electrostatic latent image by uniformly charging the photoreceptor and imagewise exposure, there are also methods for forming a latent image directly on the support using a multi-needle electrode or the like. The inventors have already proposed a method in which an electrostatic latent image is formed by injecting charges onto the magnetic head, a method in which a magnetic latent image is formed using a magnetic head, and the like.

Each of the latent image forming methods described above is capable of expressing gradation, but since the gradation expression by such methods is so-called multi-level, a large capacity of image data is required.

Therefore, an image data forming method has been proposed in which each pixel is recorded as a binary or multivalued image, a pseudo gradation is expressed based on the distribution, and the amount of image data is reduced.

To express the gradation of an image using the image data forming method, for example, multilevel recording, pulse width modulation, density pattern method, dither method, etc. are used.

The density pattern method shown in FIG. 2 is a method of converting one pixel into a plurality of pixels. sla is an original, and each pixel has a gradation. 2a is a sample for extracting a pixel 5a having a representative density value from the matrix of the document 1a and subjecting it to dark value processing; 3a is a sample M corresponding to the sample;
This is a dark value density matrix of XN, and 4a is a pattern binarized by comparing the threshold density matrix 3a and the sample 2a.

The dither method shown in FIG. 3 is a method of converting one pixel into one pixel. The original 1b is divided into density matrices for each MXN element. 2b is a sample for threshold processing corresponding to the density matrix of the original 1b, and 3b is the sample 2b.
The dark value density matrix 4b of MXN corresponding to is a pattern binarized by comparing the threshold density matrix 3b and the sample 2b.

In the conventional gradation expression method, so that the spatial frequency becomes high,
It was believed that an arrangement in which the dots were dispersed was preferable. In this method, as shown in FIG. 2 or 3, gradation is expressed by the number of dots of a fixed size (dot density). especially,
It was believed that the dither method could minimize resolution degradation.

On the other hand, a method has been proposed in which the dots are placed in a concentrated manner to give priority to gradation over resolution deterioration, and an intermediate arrangement between the two methods is also being considered.

However, in the above-mentioned multicolor image forming method, in order to eliminate the influence between toner dots directly overlapping toner images of different tones on the image forming body, it is preferable to form the writing dots at separate positions. In this case, the image density decreases, and if toner dots of different tones are formed overlappingly to ensure the image density, the next toner overlaps the first toner and shifts (the image's color tone is distorted and the gradation is distorted). I can't express myself enough.

In order to express the gradation of a multicolor image, there is a method in which toner dots of different colors are formed together within a matrix.
■There is a method in which toner dots of different colors are formed independently, but a dot pattern of a predetermined potential is formed using light projected onto the recording position, and development is performed by controlling the latent image potential and developing bias. If the diameter of the toner dots formed is large, which is often the case with ■, the developed toner dots will interfere with the image exposure in the subsequent process, and the latent consisting of the desired dots will be Since image formation is not achieved, the next toner dot is not formed, and as a result, there is a risk that the previous resolution and color balance will be disrupted, but this can be solved by regulating the diameter of the toner dots and the spacing between different toner dots.

FIG. 15 shows a three-color image forming apparatus.
The advantage is that one rotation of the photosensitive drum 51 can produce a stack of three-color toner images of yellow, magenta, and cyan.

In FIG. 15, the photoreceptor 51 is a drum-shaped photoreceptor, and is rotated in the direction of the arrow.

As shown in FIG. 15, a scorotron charger 5 is provided on the surface of the photoreceptor 51 for forming a yellow toner image.
2. An exposing device 53 and a developing device 54 are arranged, followed by a scorotron charger 56, an exposing device 57, and a developing device 58 for forming a magenta toner image, followed by a scorotron charger 60 for forming a cyan toner image. , exposure device 6
1. Developing units 62 are arranged. Therefore, in one cycle of the photoreceptor 51, toner images of three colors are stacked and formed.

In addition, 55, 59, 63 is a developing roller, 64 is a paper feeder, 66 is a transfer pole, 67 is a separation pole, 68 is a fixing device, 70
is a cleaning device.

However, although the processing speed is fast, this device does not charge
Three sets of exposure and development process units are required, which increases the size and cost of the apparatus.

Therefore, an apparatus can be considered that uses an exposure device for each color and forms multicolor toner images in layers by rotating the image forming body a plurality of times, as shown in FIG. 12.

This apparatus is an apparatus used in an embodiment of the present invention, and FIG. 12 is a cross-sectional view of a multicolor image forming apparatus, FIG. 13 is a laser apparatus applied to the image forming apparatus of FIG.
The figure shows a developing device applied to the image forming apparatus of FIG. 12.

In FIG. 12, a photoreceptor drum 11 is a photoreceptor that rotates in the direction of the arrow, and a uniform charge is applied onto the photoreceptor 11 by a scorotron charger 12. This uniform charge is subjected to image exposure by the following image exposure means to form an electrostatic charge image.

For example, a laser device 14 shown in FIG. 13 is used as an exposure system, and image exposure is performed by laser light from the device 14, so that electrostatic latent images corresponding to each color are formed on the photoreceptor 11.

Among the electrostatic latent images corresponding to the respective colors, the electrostatic latent image corresponding to yellow is formed by irradiation with laser light modulated by yellow data.

The electrostatic latent image corresponding to yellow is transferred to the first developing device 1.
5 to form a first toner image (yellow toner image) on the photoreceptor 11.

This first toner image is transferred to the recording paper P after the image forming body is neutralized by the static elimination lamp 40, and is transferred to the photoreceptor 1.
1 is again charged by the scorotron charger 12.

Next, the laser light is modulated with magenta data, and the modulated laser light is irradiated onto the photoreceptor 11 to form an electrostatic latent image. This electrostatic latent second toner image (magenta toner image) is formed.

The third developing device 17. Fourth developing device 18
A third toner image (cyan toner image) and a fourth toner image (black toner image) are formed by sequentially developing a four-color toner image that is sequentially stacked on the photoreceptor 11.

These four-color toner images are similarly discharged from the image forming body by the discharge lamp 40, then re-charged by the charger 19, and placed on the recording paper P fed from the paper feeder 20 at the transfer pole 2.
It is transferred by the action of 4. It is desirable that the charging here has a charging property comparable to that of the charging by the scorotron charger 12. By doing so, the conditions can be made the same as those of the previously recharged toner, and the transferability is improved. Charger 19
A Scorotron charger is preferred.

Here, 23 is a paper feed roller, and 22 is a guide plate.

The guide 2 is separated from the photoreceptor 11 by the separation electrode 25.
6 and conveyor belt 27 to the fixing roller 28
The sheet is carried into the paper tray 29, heated and fixed, and then discharged onto the paper discharge tray 29.

On the other hand, after the transfer of the photoreceptor 11 has been completed, the static electricity is removed by the static eliminator 31, which was not used during the toner image formation, and the toner remaining on the surface is removed by the blade of the cleaning device 30, which was not used during the toner image formation. 32 and a fur brush so as not to interfere with the subsequent multicolor image formation.

However, in any of the image forming apparatuses controlled as described above, the printing speed is the same in the process of forming an image on the image forming body regardless of whether the size of the formed image is large or small.

In other words, the circumference of the image forming body (which can be the shape of a drum or belt) is determined so as to accommodate the maximum image size, and when forming a small image size, there is a disadvantage that a wasteful part is generated. It had

[Object of the Invention] The present invention eliminates the drawbacks of the conventional ones as described above, and effectively utilizes an image forming member to increase the printing speed when printing an image size smaller than the maximum image size. An object of the present invention is to provide a multicolor image forming apparatus that can improve work efficiency.

[Summary of the invention]

The present invention is a multicolor image forming apparatus that can change the number of images formed on an image forming body according to the size of one unit of image. For example, the size of a document used in an office to form one unit of image is usually A-3, A-4, B-4, B-5, etc. in terms of paper size.
When used as a printer or copier for this purpose,
The circumferential length and width of the image forming body must be large enough to include at least the maximum paper size. In other words, the perimeter needs to be longer than the paper size.

However, for example, although the length of A-3 is 420 mm, which is twice the length of A-4, the printout speed is A-3 in the multicolor image forming apparatus as described above.
-3 and A-4 are exactly the same. This is because when printing an A-4 size image, half of the image forming body is completely unused (in the case of the same size).

Therefore, the present invention attempts to improve the printing speed by forming a plurality of toner images when the image size is such that a plurality of toner images can be stored on the image forming body.

For example, for a drum-shaped image forming member that can print a maximum of A-3, when the unfolded state is shown in FIG.
It is slightly larger than the circumference of the paper wrapped around it, and two A-4 sheets can be placed vertically within this size. Of course, two cards can be inserted in the case of B-5 as well.

Image size information (set by the user, included in the image data, determined by the size of the paper used, or when using an image reading device, determined from the detection of the document size in addition to the above) two images are formed in parallel on the image forming body.

That is, after charging the image forming body, image exposure of the first image is performed, then image exposure of the second image is performed, and then a development process using yellow toner is performed, and the toner used is Masenda toner, While changing with cyan toner 3
Repeat ~4 times (fourth time using black toner). The plurality of multicolor toner images formed in this manner are transferred onto a sheet of paper that is conveyed in synchronization with each image, and then discharged.

Further, the present invention may be configured so that, for example, the circumference of the image forming body is set to a length that can accommodate a plurality of images of the maximum size, and a larger number of images of a smaller size can be accommodated.

After image formation, for example, if the first image can be repeated, rapid multiple printing will be possible, in which case multiple copies of the same image will be formed on the image forming body, and different images will be printed. If writing is possible, fast page printing will be possible, and in this case, a plurality of different images will be formed on the image forming body.

[Embodiments of the invention]

Examples of the present invention will be described below, but the examples of the present invention are not limited thereto.

[Example 1] First, an example of a method for forming image data will be explained.

In the multicolor image forming method of the present invention, for example, an output signal of an image sensor that scans a multicolor original, a transmission signal from another device such as a facsimile, or data stored in a storage device is used as image data.

The image data typically includes three primary color data Y i , M 1 % CI, yellow, magenta, and cyan, and black data BKi.

When forming such a multicolor image, image data is input to the arithmetic processing section of the color correction section shown in FIG. 4, and desired four-color data is calculated using, for example, the following arithmetic expression (I).

Arithmetic formula [1] Ym=α+ Yi-β, min (Yi, Mi, Ci)
Mm=cr, Mi−βz min (Yi,, MiSC
i] Cm=α, Ci-β, min (Yis MiSC
i) BKm=a, BKI-β, min (YL, Mi,
Ci) However, Ym, Mm, Cm are the data after calculation, Yi,
Mi, Ci are input image data, α1, α2, α3
, α4, β1, β2, β3, and β4 are color correction coefficients based on external factors such as development conditions, and m1n (Yl, Mi, Ci) is the color tone with the minimum density value among the three primary colors of yellow, magenta, and cyan. It shows.

Next, in order to understand the calculation formula [1], α1~α4, β1~
An example in which β4 is all 1 will be explained below.

If the color tone of the minimum density value is cyan (CL) as shown in Figure 5, then by subtracting the density corresponding to cyan from each of the three primary colors and gathering them together, the black component can be obtained from the principle of subtractive color method. It will be done.

This black component is added to black data BKi to obtain black image data as shown in FIG. Furthermore, the remainder after subtracting the cyan density equivalent from each of the three primary colors is used as image data of the three primary colors as shown in FIG.

(Improvement of color balance during development, toner, −
It saves consumption and improves the efficiency of developing operations.

Four-color data Y color-corrected by the arithmetic processing unit in FIG. 4
ms M ms Cms B K m is 4-color data Y O% which is compared with a threshold value matrix to be described later and is binarized.
Mo, Co, and BKo are obtained.

This data is stored in memories M y , MmSM c ,
Four types of developing devices containing yellow, magenta, cyan, and black toners are stored in the Maw, but are output to the exposure system according to commands from the control unit, and an electrostatic charge image is formed on the photoreceptor. , preferably developed without contact.

In this way, toner images of four colors are stacked and formed on the photoreceptor, and are transferred and fixed onto a recording paper that is fed in synchronization with the photoreceptor to form a multicolor image.

As the darkness value matrix used in the present invention, for example, spiral matrices YP, MP, CP, and BKP, which are distributed separately for each color, as shown in FIG. 7 are used.

The toner image obtained using such a darkness value matrix is
It is composed of concentrated dots such as YD, MD, CD, and BKD, and gradation is expressed depending on the size of the dots. Moreover, since the dots of each color do not overlap each other, a clear multicolor image with extremely excellent color balance can be obtained.

In this case, to express the gradations of a multicolor image, two methods are considered: one is to form different toner dots, and the other is to form toner dots of different colors in groups within a matrix.

In the case of the former method, examples of the matrix in this case are shown in Fig. 8(a) and (b), and Fig. 8(a) is an 8x8 matrix.
It is a matrix, and each color is made up of 4×4 submatrices arranged alternately in Y, M, C, and BK. For example, where the Y symbol is attached, when yellow data is input, it is compared with the dark value and printed (10th
(black circle in the figure) or non-printing (white circle in Figure 10) is determined, but data for other colors is not input.

Figure 8(b) is a 6x6 matrix, and each color is regularly arranged, but the corresponding BK in Figure 8(a)
are not formed in the matrix.

The arrangement of the darkness values of the submatrix forming the toner image of each color may be distributed, concentrated, or a mixture thereof.

In the latter method, toner dots of different colors are formed in groups within a matrix, and the arrangement of the toner dots of each color is either dispersed, concentrated, or a mixture thereof.

Figures 9(a) and 9(b) show examples of matrices in this case. Figure 9(a) is an 8x8 matrix, and each color is composed of a 4x4 submatrix. ing. Figure 9(b) is a 6x6 matrix, and each color consists of three 2x2 sub-matrices, and this configuration consists of the matrices in Figures 8(a) and (b) and the matrix in Figure 9(a). It can also be called an intermediate arrangement with the matrix.

In addition to the gradation expression method described above, a gradation expression method may also be used in which toner dots of each color are distributed within a matrix pattern so that at least a portion of the dots overlap.

In this case, there is a problem that a desired latent image is not formed because the charged portions of the molded portions are different from those of the non-overlapping portions, or the image exposure is blocked by previous toner dots and does not reach the image forming member sufficiently.

In the present invention, even if dots of different colors overlap each other, the above-mentioned disadvantages can be avoided by overlapping toners in order of higher translucency or by using a concentrated dot structure instead of the conventional dispersed dot structure. In addition to reducing this, it is even better to change the angles of the different color toner dots to prevent the occurrence of moiré, reduce the overlap between the different color toner dots, and allow each color tone to be displayed visually.

Next, a case in which a large number of identical prints (continuous copies) are obtained will be specifically described below with reference to the drawings of the first embodiment.

FIG. 12 is a sectional view of a multicolor image forming apparatus for explaining this embodiment, FIG. 13 is a laser device applied to the image forming apparatus shown in FIG. 14, and FIG. 14 is a sectional view applied to the image forming apparatus shown in FIG. This figure shows the developing device used.

Note that details regarding the drawings are omitted because they have been described above.

diameter 18 that rotates at a linear velocity of 180 ss/s e c in the direction
A uniform charge of +600V is applied onto the photoreceptor 11 by a scorotron charger 12, which is a 0n selenium photoreceptor. This uniform charge is subjected to image exposure by the following image exposure means to form an electrostatic charge image.

That is, the A-4 size data Yi, Mi, Ci, and BKi stored in advance in the storage device are input as image data to the arithmetic processing section of the color correction department shown in FIG. Calculated and color corrected data Y
m, Mm, Cm, and BKm are obtained and compared with the dark value matrix in FIG. 7 to obtain binarized data YO1Mo,
Co and BKo are obtained.

These data are stored in memories My, Mm, and Mc.

Although it is stocked in Mll+, it is output to the exposure system according to a command from the control section.

In this embodiment, the laser device 14 shown in FIG. 13 is used as an exposure system.
is used, an electrostatic latent image of the ray from the device 14 is formed, and by imagewise exposure of the data from the memory, two identical A-4 size static images corresponding to each color are formed on the photoreceptor 11. A latent image is formed.

Details of the laser device 14 are shown in FIG.
The helium-neon laser output from the source 33 is
The signal is inputted to an acousto-optic modulator (AOM) 34 through reflecting mirrors 37 and 38, where it is modulated by the binarized image data.

This modulated laser light is polarized by a mirror scanner 35 made of a rotating octahedron, and is polarized by an imaging f-theta lens 36.
Image exposure is performed by scanning the surface of the photoreceptor 11 at a constant speed through the photoreceptor.

Note that 39 is an inspection device that determines the writing position of the laser beam.

Among the electrostatic latent images corresponding to the respective colors, the electrostatic latent image corresponding to yellow is formed by irradiation with laser light modulated by yellow data.

The yellow data is data that has been binarized using the YP matrix shown in FIG.

In addition, the darkness value matrix YP, MP of each color.

In CP and BKP, where no numbers are shown, black data is not output even if the corresponding data is input, that is, it is not applied as with the white circles in FIG.

The electrostatic latent image corresponding to yellow is transferred to the first developing device 1.
5, and two first toner images (yellow toner images) are formed on the photoreceptor 11.

This first toner image is not transferred to the recording paper P,
+60 again on the photoreceptor 11 by the scorotron charger 2
A charge of 0V is applied.

Next, the laser light is modulated with magenta data binarized using the dark value matrix MP shown in FIG. 7, and the modulated laser light is irradiated onto the photoreceptor 11 to form an electrostatic latent image.

This electrostatic latent image is developed by a second developing device 6 to form two second toner images (magenta toner images), and dark value matrices CP, , BKP are formed in the same manner as above.
are used sequentially, the third developing device 17 and the fourth developing device 18
The two third toner images (cyan toner images) and the two fourth toner images (black toner images) are sequentially reversely developed by
are formed, and two four-color toner images sequentially stacked on the photoreceptor 11 are formed.

In order to avoid damaging the toner image formed on the image forming body and to avoid supplying unnecessary toner to the latent image, the developing device that is not used for development cuts off the alternating current bias component during development (when it is ON) when the development is OFF. Examples of methods include applying only a DC bias component to the toner, leaving it in a floating state, grounding it, or applying a DC bias with a polarity opposite to that of the toner. Other methods include separating the developing device from the image forming body or removing the developer from the developing sleeve. Alternatively, it may be used in combination with the above bias change.

These four-color toner images are charged by a charger 19, continuously supplied from a paper feeder 20, and transferred.

Here, 23 is a paper feed roller, and 22 is a guide plate.

The recording paper P carrying the transferred toner image is separated from the photoreceptor 11 by the separation electrode 25, conveyed by the guide 26 and the conveyor belt 27, carried to the fixing roller 28, heated and fixed, and discharged onto the paper discharge tray 29.

On the other hand, after the transfer of the photoreceptor 11 has been completed, the static electricity is removed by the static eliminator 31, which was not used during the toner image formation, and the toner remaining on the surface is removed by the blade of the cleaning device 30, which was not used during the toner image formation. 32 and a fur brush so as not to interfere with the subsequent multicolor image formation.

Next, a developing device suitable for use in the multicolor image forming apparatus shown in FIG. 12 will be described.

Development in carrying out the present invention can be either normal development or reversal development, and although there is no development, the toner image that has already been formed is not disturbed during development.
The developing layer containing toner does not come into direct contact with the surface of the image forming body.
That is, when there is no constant potential difference between the developer transporting member such as a sleeve and the image forming member, the developer layer thickness (hereinafter referred to as It is preferable to use a developing method called non-contact development, in which the developer layer thickness in the developing area (simply referred to as developer layer thickness) is set to be smaller than the gap between the developer transporting body and the image forming body.

It is preferable to apply an oscillating electric field to the developing area.
Publication No. 238295 and Patent Application No. 2382 of 1982
It is preferable to apply the voltage under the conditions described in Japanese Patent No. 96.

Four developing devices are used as the developing device, but these devices may have the same or similar structure, and a representative cross-sectional view of the first developing device 15 is shown in FIG. 14.

This developer is deposited by rotating the magnetic roll 41 having 16 poles at a speed of 100 Or, p, m in the direction of arrow F, and by rotating the sleeve 42 with a diameter of 30 fins in the direction of arrow G at a linear speed of 120 ml sec. , transported in the direction of arrow G.

This developer layer is a two-component developer, and its thickness is regulated by a spike regulating blade 43 during transportation, so that a developer layer having a developer layer thickness of 0.5 mm in the developing area is formed.

A stirring screw 45 is provided in the developer reservoir 44 to sufficiently stir the developer reservoir, and when the developer reservoir in the developer reservoir 44 is consumed, the toner supply roller 46 rotates. By this, toner hopper 4
Toner T is replenished from 7 onwards.

Next, the gap between the sleeve 42 and the photoreceptor tram 11 is set to 0.8 fin, and a DC power supply 48 is provided between the sleeve 42 and the photoreceptor tram 11 to apply a developing bias in order to perform reversal development. An alternating current power source 49 is provided in series with the direct current power source 48 so that the photosensitive drum 11 can be sufficiently supplied with developer by vibrating in the area E.

Note that R is a protective resistance.

Here, the developing bias is such that the charging potential of the image forming body is +6
When it is 00V, the DC component is, for example, +500V, and the AC component is 2KHz, with an effective value of 1.5KV. In the developing device 15, the toner T in the developer conveyed by the sleeve 42 is charged with a charge amount of 20 μC/g before reaching the development area.

(Hereinafter, blank space) On the other hand, as a developer used in such a machine, a two-component developer composed of toner and a carrier, and a one-component developer composed only of toner can be used.

Two-component developers require control of the amount of toner relative to carrier, but have the advantage that triboelectric charging of toner particles can be easily controlled. In addition, especially with two-component developers consisting of a magnetic carrier and non-magnetic toner, it is not necessary to contain a large amount of black magnetic material in the toner particles, so it is possible to use color toner that does not cause color turbidity due to magnetic material. It has the advantage of being able to form clear color images.

It is particularly preferable that the two-component developer used in the present invention is composed of a magnetic carrier as a carrier and a non-magnetic toner as a toner.

The composition of the toner is as follows.

■ Thermoplastic resin: binder 80-90wt% Examples: polystyrene, styrene acrylic polymer, epoxy resin,
A mixture of polyamide resin polyethylene, ethylene vinyl acetate copolymer, etc. is used.

■ Pigment: Coloring material 0-15wt% Example: Black: carbon black Cyanide: copper phthalocyanine, sulfone amide dielectric dye Yellow: benzidine derivative Magenta: Rhodamine B lake, car Min 6B etc.

■ Charge control agent 0-5wt% Positive donor: Many nigrosine-based electron-donating dyes,
In addition, alkoxylated amines, alkylamides, chelates, pigments, quaternary ammonium salts, etc.

Negative toner: Electron-accepting organic complexes are effective, and in addition, chlorinated paraffin, chlorinated polyester, polyester with excess acid groups, chlorinated copper phthalocyanine, etc.

■ Examples of fluidizing agents: Typical examples are colloidal silica and hydrophobic silica.
Other products include silicone face, metal soap, and nonionic surfactants.

■ Cleaning agent Prevent toner filming on the photoreceptor.

Examples: fatty acid metal salts, oxidized silicon acids with organic groups on the surface,
There are fluorine-based surfactants.

■ Filler The purpose is to improve the surface gloss of images and reduce raw material costs.

Examples: calcium carbonate, clay, talc, pigments, etc.

In addition to these materials, a magnetic material may be included to prevent fogging and toner scattering.

As magnetic materials, triiron tetroxide, r-ferric oxide, chromium dioxide, nickel ferrite, iron alloy powder, etc. with a diameter of 0.1 to 1 μm have been proposed, but at present, triiron tetroxide is the most common. It is used in an amount of 5 to 7 Qwt% based on the toner. The resistance of toner varies considerably depending on the type and amount of magnetic powder, but in order to obtain sufficient resistance, the amount of magnetic material must be 55%.
It is preferable to make it less than wt%.

In addition, in order to maintain clear colors as a color toner,
It is desirable that the amount of magnetic material be 3Qwt% or less.

In addition, resins suitable for pressure fixing toners include approximately 2
Adhesive resins such as wax, polyolefins, ethylene-vinyl acetate copolymers, polyurethane, and rubber are selected so that they will plastically deform and adhere to paper with a force of about 0 kg/am, and capsule toners may also be used. can.

A toner can be made using the above-mentioned materials by a conventionally known manufacturing method.

In the configuration of the present invention, in order to obtain a more preferable image, it is desirable that the particle size of these toners is below the resolution. The toner particle size is preferably 1 to 50 μm, particularly preferably 5 to 20 μm, and has an average charge amount of 3 to 300 μC/g in view of resolution, toner scattering, and transportation.
, particularly preferably 10 to 100 μC/g.

When the weight average particle diameter of the toner is less than 1 μm, it becomes difficult to separate from the carrier, and when it exceeds 20 μm, the resolution of the image decreases. In this embodiment, toners having a weight average particle size of 10 μm are used for all four colors.

In addition, in order to create delicate points and lines or to improve gradation, magnetic carrier particles may be particles made of magnetic particles and resin, such as a resin dispersion system of magnetic powder and resin, or resin-coated magnetic particles. It is also more preferably spherical.

In this example, carrier particles having a weight average particle diameter of 50 μm were used for all four colors. The weight average particle diameters of the toner and carrier were measured using a Coulter Counter (manufactured by Coulter Inc.).

In order to avoid the problem that charges are easily injected by the bias voltage of the child particles, especially the oscillating voltage, and carriers tend to adhere to the surface of the image forming body, or that the bias voltage is not applied sufficiently, The carrier should preferably have an insulating resistivity of 10 IΩ or more, preferably 10I3Ω1 or more, and more preferably 10'4Ω1 or more, and with these resistivities, the particle size should be as described above. A 5Qe-mu resin-dispersed carrier having a specific resistance of 1014 Ω1 or more was used.

Further, the stiffness resistance of the carrier is measured by the following measuring method.

That is, after the particles are placed in a container with a cross-sectional area of 0.50- and tapped, 1 kg/c is applied onto the packed particles.
Apply a load of sl, and apply 100OV between the load and the bottom electrode.
It is determined by applying a voltage that generates an electric field of /ell, reading the value of the current flowing at that time, and performing a predetermined calculation. At this time, the thickness of the carrier particles is 1fi.
It is considered to be a degree.

The method for manufacturing such a finely divided carrier is to coat the surface of the magnetic material with the resin by using the magnetic material and thermoplastic resin described for the toner, or to coat the surface of the magnetic material with the resin, or to coat the particles with a resin containing dispersed magnetic particles. It can be obtained by preparing particles and selecting the particle size using a conventionally known average particle size selection means.

It is desirable to improve the agitation performance of the toner and carrier and the transportability of the developer, as well as to improve the charge control performance of the toner and to make the toner particles and the carrier spherical. For resin-coated carrier particles, magnetic particles should be as spherical as possible and coated with resin, and for magnetic fine particle dispersion carriers, magnetic fine particles should be used as much as possible to prevent the particles from dispersing resin. It is manufactured by performing a spheroidization treatment using hot air or hot water after particle formation, or by directly forming spherical dispersed resin particles by a spray drying method.

When a four-color image with gradation was formed under the above conditions, a clear image with high detection power, excellent gradation, and good color balance was obtained. Also, clear records of characters, line drawings, etc. were obtained.

[Example 2] Next, an outline of a color image forming system having an input system will be explained with reference to FIG. 16.The image reading device and printer are those that can handle up to A3 size. This is what I used.

The recording device, dot pattern memory, and image forming process are controlled by control signals from the CPU, such as the exposure system (lamp 2, mirrors 6a, 6b, 6c) shown in FIG.
As the document moves, a COD image sensor 4, which is a type of color scanner, reads color information of B (blue), G (green), and R (red) in the horizontal direction of the document, and outputs an analog video signal.

Shading correction is performed to remove distortion caused by etc., and each B, G
, R correspond to the same image position. Then the BSG from the buffer memory.

The R signal is subjected to complementary color conversion to Y (yellow), M (magenta), and C (cyan), and after tone correction, Y, M
Extract the black component (UCR) from each SC data,
Separate into chromatic color components and achromatic color components.

Here, the chromatic color components Y, M, and C are subjected to color correction and gradation correction together with the black component (BK), and then input to a pattern generator (PG). Here, dither processing based on the dither method described above is performed to convert the signal into a digital dot pattern signal, which is stored in a page memory for each color. The Y dot pattern is then output to the recording device via a line memory required as a buffer, and two identical first toner images are written and imaged. Similarly, the pad pattern, BK dot pattern, etc. are taken out one after another in accordance with the writing timing, written, and an electrostatic image is formed and developed.
Two color toner images are formed.

The outline of the system is configured as shown above. According to the above method, the image forming body can be used effectively, and the printing speed of A-4 is twice that of A-3.

In addition, when obtaining page prints, image exposure is performed in the same manner as above using the first A-4 size yellow data, and then the second A-4 size yellow data is transferred and the image is Exposure is performed. Note that the data may be transferred in advance for two images and stored in the memory.

In this way, an electrostatic latent image consisting of two types of images is formed on the image forming member, and then this is developed with yellow toner. By repeating this process for magenta data, cyan data, and black data, two multicolor toner images are formed on the image forming body, and this toner image is then transferred.
Take root. In this way, the 3rd and 4th, 5th and 6th
You can print the second page.

[Embodiment 3] Next, a case will be described in which toner images are sequentially formed on an image forming body in synchronization with an image reading device without using the frame memo 11.

First, image reading devices and printers are up to A3
It can handle up to any size.

In this case, when a document A-3 is placed on the image reading device, image reading and writing on the image forming body are performed synchronously, and by repeating this, a multicolor toner image is formed on the image forming body. can be formed.

In addition, when the originals are A-4, the two originals ASB are arranged in parallel, and multicolor toner images corresponding to the two originals are formed on the image forming body by the same operation as for the A-3 original. do. The two multicolor toner images formed in this way are document A.

An image forming apparatus using two such documents is shown in FIG. 18 and FIG. 19, and the time chart is shown in FIG. 18 and FIG. 19. As shown in FIG. 20, EYl, EMl, E
C1, , EBl corresponds to the so-called patch written for the formation of a reference toner image, and the development timing is DY, DM, , DC to develop this by each developing device.
,,DBI), toner density control is performed from the development state. There is also a mode in which this information (punch information) is fed back to the charging potential, exposure intensity, and development bias.

In the figure, a high level indicates that each means is being driven.

Also, RA+ , RBt , RAz , RBz in Fig. 16
RA3, RBs, RA4, and RBa indicate the timing when the ASB original is read by the scanner, and are shown in Fig. 16v.
Y, vM1vCSvB are the charging timings EYzm, E Y z *, EMo, EM, 1,
ECzaSEC, , E B ta, and E B tm are timings RA+ 1RB+ , RAz, and RB, respectively.
At the timing of writing the yellow, magenta, cyan, and black information read by t, RAs, RBa, RAa, and RB4, respectively, the written information is written at the timing D Yz, D Mt 1D Ct - DB! Yellow, magenta, cyan, and black are developed using developer unit 1.
5.16.17.18.

In FIG. 16, the timing chart is such that document A is read first, corresponding to FIG. 15, or in FIG. 14, document B is read first.

As shown in Figs. 18 and 19, when an image reading device has a device (automatic document feeder) that automatically feeds and prints multiple sheets of originals, it is possible to detect the paper size or specify the paper size. In the case of A-4 size, two originals are fed, read, and a multicolor toner image corresponding to the two originals is printed.Furthermore, if multiple originals are to be copied, each original is ejected to the paper ejecting device. Because the images are mixed together, two prints are ejected as a set and multiple copies are made.

FIG. 18 is a schematic diagram of an example of an image forming apparatus using a document feeder that sets the document with the surface facing down.
The figures show schematic diagrams of other examples of image forming apparatuses using a document feeder that sets the document with the surface facing up. The same members as those shown in the figures are designated by the same reference numerals and their explanations are omitted.In the case shown in FIG. Place the originals so that the side with the image you are trying to record is facing down, then start copying and copy the two originals B and A.
is fed and set on the document table. Then, an optical system consisting of an exposure lamp 2, mirrors 6a, 6b, 6c, and a lens 3 scans the photoreceptor 1, which is an image forming body, while scanning information starting from the left side in the figure and making the COD image sensor 4 read the information.
Image exposure is carried out on 1.

After the predetermined operation is performed, the prints of manuscripts A and B are discharged onto the paper discharge tray of the printing device 8 (a sorter is used in the embodiment) in the order of B and A, face up. Page alignment is performed.

In addition, in the case shown in FIG. 19, the automatic document feeder 7
Place a multi-sheet A-4 original with the front side facing up.
Next, by starting copying, two originals B and A are fed and set on the original platen 1. And exposure lamp 2
, an optical system consisting of mirrors 6a, 6b, 6c and lens 3 scans starting from the right side in the figure and causes the COD image sensor 4 to read the information, while image exposure is performed on the photoreceptor 11 which is an image forming body. .

After a predetermined operation is performed, the prints of documents A and B are discharged onto the paper discharge tray of the paper discharge device 8 in the order of A and H, with the front side facing down, so that the pages are aligned.

In addition, in the case of original A-4, the image reading scan is A-4.
The reading process may be performed twice during one rotation of the photoreceptor, in which the image is read up to , and then quickly returned to its original position and the image is read again. By doing so, two identical toner images can be formed on the photoreceptor, and the printing speed can be increased. In this case as well, there is no need to provide a frame memory.

[Example 4] In Example 3, image reading and image formation are performed synchronously and a frame memory is not used. However, when a frame memory is used, the same process as in Example 2 is performed. You can print without synchronizing by
Since frame memories are expensive, it would be too expensive to prepare multiple equinoxes, so while image reading and image formation are synchronized, the image reading data at that time can be stored in the frame memory and used for later image formation.

That is, in this embodiment, only A-3 or A-4 is sufficient.

When one sheet of A-4 original is prepared, the image reading and image formation of this one sheet of original are performed synchronously, while the signal from the image reading is stored in the frame memory.
Next, it is called to write the second sheet and form an image.

As a result, two identical toner images are formed on the image forming body.

This step is repeated 3 to 4 times for each color to form two multicolor toner images, which are then transferred onto a sheet of paper conveyed in synchronization with each image and discharged.

The time chart in this case is shown in Figure 21,
FIG. 21 shows that each means is driven at a high level.

In addition, RA+, RAz, RA3, and RA4 indicate the timing at which the original is read by the scanner, and VY, VMt
, VC, , vB are charging timings for yellow, magenta, cyan, and black development, respectively, and EYz
, EMz , ECz , EBtRA This is the timing to write the yellow, magenta, cyan, and black information read by a, and it is also the timing to write the yellow, magenta, cyan, and black information read by R At , RAt -RAs , Rfi stored in the frame memory at the same time as reading.
The contents of -a are EYo' and EMz', respectively.
, ECz', EBz', and all the written information is written at the timing DYz, DMt.
, DCx, and DBz, yellow, magenta, cyan, and black are developed by the developing device 15.16.17.18.

Also, unlike the embodiment 3', the image reading device is A-4.
It is also possible to scan the original and return to the initial position. In Fig. 21, the first sheet to be recorded first is recorded without passing through the memory, and the second sheet is recorded from the data in the memory. However, it is also possible to quickly scan the original, store image data in memory, and record using the data.

Note that EY+ 1EM+ 1ECt and EBt correspond to the so-called patch written for forming the reference toner image as described above, and are developed by each developing device.
From the development state, toner density control, charging potential,
It is used by being fed back to the exposure intensity and development bias.

Furthermore, if the image reading device is equipped with a device (automatic document feeder) that automatically feeds multiple sheets of originals, all you need to do is feed the next document after printing is completed and repeat the above operation, and the paper ejecting device will automatically feed multiple sheets of originals. All you have to do is change the paper discharge tray for each convenience store.

Note that the frame memory used in Example 2 and this Experimental Example 4 changes its contents according to the color signal from the image reading device, but it can be If a large number of copies are to be made), the image can be read once and stored in a frame memory, and this frame memory can be used to print any number of copies.

Furthermore, although the above embodiments have been described using the same magnification as an example, the idea of the present invention can also be used in the case of variable magnification.

For example, when reducing an A-3 size document to A-4 size or B-5 size or cutting out A-4 or B-5 size, the sequence is changed to form a plurality of images on the photoreceptor.

Conversely, when enlarging A-4 size to A-3 size, the sequence is changed to form one image on the photoreceptor.

In this way, it becomes possible to utilize the image forming body effectively.

〔Effect of the invention〕

With the above configuration, this invention can print multiple originals or print multiple sheets in the time required to print the maximum image size if the size fits within the maximum image size. It has an excellent effect in that it can be done in a very short time.

[Brief explanation of drawings]

3 and 3 are diagrams showing the relationship between density distribution, threshold value groups, and patterns, and FIG. 4 is a diagram showing the arithmetic processing unit of the color correction department.
Figures 5 and 6 are diagrams showing density values, Figures 7, 8 (a) (b) and Figure 9 (a)) are diagrams showing matrices, and Figure 10 is a diagram showing patterns. , FIG. 11 is a diagram showing an expanded state of the image forming body, FIG. 12 is a schematic diagram showing a multicolor image forming apparatus, FIG. 13 is a schematic diagram showing a laser device, and FIG. 14 is a schematic diagram showing a developing device. 15 is a schematic diagram showing a multicolor image forming apparatus, FIG. 16 is a diagram showing an outline of a color image system, FIG. 17 is a diagram showing an exposure system, and FIGS. 18 and 19 are multicolor A schematic diagram showing the image forming apparatus, and FIGS. 20 and 21 are time charts showing the operation of each part of the multicolor image forming apparatus. ■...Original table 2...Exposure lamp 3...Lens 6a, 5 b, 5 c...Mirror 7...
... Automatic document feeder 8 ... Paper discharge device 11.51 ... Image forming body 12.52 ... Scorotron charger 14.53
．． 57.61... Exposure device 15.16.17.1
8 54.58.62 ...Developer 24.6
6... Transfer pole 25.67... Separation pole 48... DC bias power supply 49... AC bias power supply T... Toner D. ...Developer P...Recording paper Yi,, ML C1% BKi...Image data from external memory Y j'ln SM mSC' s B K' ””
"" Data after color correction in the arithmetic processing unit YO,, MO% 00% BK k...-Binarized data M ys M ITI, M Cs M vr*
...Image data of each color data memory Fig. 4 Fig. 5 Fig. 6 Fig. 7 YP MP CP BKP Fig. 8 (G) (b) Fig. 9 (G) (b) Fig. 10 Fig. 11 Ward, l Fig. 14 0) S N Fig. 15 Fig. 17 Fig. 18

Claims (1)

[Claims] A multicolor image formed by repeatedly performing the steps of writing an image on an image forming body to form a latent image, developing the latent image to form a toner image, and superimposing each color toner image on the image forming body. A multicolor image forming apparatus, characterized in that the forming apparatus is configured to form a plurality of units of images on the image forming body depending on the size of the one unit image to be formed.