JP2856088B2 - Image forming method and apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming method and apparatus, and more particularly, to forming a latent image on a latent image carrier based on image information and developing the latent image to visualize the latent image. The present invention relates to a novel image forming method and an apparatus effective for an electrophotographic type.

[0002]

2. Description of the Related Art In a printer or a copying machine, a digital electrophotographic system is widely adopted as a system capable of providing high speed and high image quality. In this method, optical scanning of a photosensitive medium is performed using a light beam, and in order to reproduce the gradation of an image, pulse width modulation exposure using an analog screen generator or the like, or light emission intensity of the light beam is varied. Many intensity modulation exposures are performed (see, for example, JP-A-1-280965 and JP-A-2-63756). Then, the latent image on the photosensitive medium obtained by the exposure is visualized using a liquid or a powder toner.

In these systems, recording is performed by forming and developing a latent image with a constant recording density regardless of the presence or absence of adjacent pixels. Therefore, in order to realize a higher recording density, a latent image forming technique and a developing technique for reproducing even smaller dots and parallel lines with a smaller interval are required.

[Problems to be solved by the invention]

However, in order to realize a high recording density, there is a technical problem that as dots become smaller and intervals between lines become narrower, it becomes difficult to satisfactorily reproduce dots and lines. It was observed. After examining this point, as shown in FIG. 23, the increase in the recording density of the latent image can be dealt with to a certain level by, for example, reducing the diameter of the light beam. Even if a latent image with a high recording density is formed, which does not reach the level at which the recording density can be achieved, the resolution of the latent image is impaired at the stage of developing the latent image by development (the visible image is crushed, the toner Scattered).

As means for solving such technical problems, for example, the carrier diameter of a two-component developer constituting a magnetic brush is reduced, or the distance between a developing electrode and a latent image on a photosensitive medium is increased. In any case, there is provided a technique for narrowing the image, but in any case, the response of development is far from reaching a level at which a high recording density of a latent image can be obtained.
After all, the present situation is that the latent image must be visualized within the range of the responsiveness of the developing system.

SUMMARY OF THE INVENTION The present invention has been made to solve the above technical problem, and compensates for the inadequate response of the developing system to a latent image having a high recording density. It is an object of the present invention to provide an image forming method and an image forming apparatus capable of easily realizing a higher recording density.

[0007]

The inventors of the present invention have examined the frequency response characteristics of various developing systems of the electrophotographic system, and have obtained the results shown in FIG. In the figure, the horizontal axis is the spatial frequency (means the recording density of the latent image)
The higher the spatial frequency, the smaller the recording dot diameter, the shorter the interval between lines, and the higher the recording density. The vertical axis is the ratio between ΔDout (output image contrast) and ΔDin (input image contrast). In the case of powder development, the value of the spatial frequency indicating the peak and the magnitude of the spatial frequency in each of the graph curves in FIG. In the case of liquid development, it depends on the solvent viscosity, the electric resistance, the distance between the developing electrode and the latent image, and the like.

As can be seen from FIG. 2, no matter what development carrier or solvent is used, if the recording density is increased, no response is finally obtained. That is, even if dots or lines are formed on the latent image, the latent image is not reproduced well, and the image becomes a crushed image. However, if the recording density is low, the developing system responds, faithfully reproduces the dots and lines of the latent image, and good dots and lines are obtained. In particular, at a recording density at which a peak is shown, even better dots and lines are reproduced.

The image forming method according to the present invention, based on the above considerations, divides a recording pixel group of a high recording density image into a plurality of recording pixels so that a developing system can respond to the plurality of latent images having a low recording density. Are obtained, and after forming the respective visualized images, the respective visualized images are synthesized and restored to the original high recording density image.

That is, in the image forming method according to the present invention, as shown in FIG. 1A, a latent image is formed on a latent image carrier based on image information, and the latent image is developed to form a visible image. In the image forming method, the constituent pixel group of the image information G is divided into a plurality of pixels so that there are no adjacent pixels in the main scanning direction. The latent image formation and development are repeated on the basis of the divided image information Gd to form a developed image corresponding to each divided image information, and the divided images formed in the divided visual image forming step B are formed. A divided visual image synthesizing step C in which a visual image corresponding to the information Gd is aligned and superimposed on a transfer medium.

As shown in FIG. 1 (b), an apparatus for embodying such an image forming method comprises a latent image forming means 2 for forming a latent image on a latent image carrier 1 in accordance with image information. A developing unit 3 for developing the latent image on the latent image carrier 1 with toner to visualize the latent image; and a transfer unit 4 for transferring the toner image developed by the developing unit 3 to a transfer medium 5. In the image forming apparatus, an image dividing unit 6 that divides a group of constituent pixels of the image information G into a plurality such that there is no adjacent pixel in the main scanning direction, and each divided image divided by the image dividing unit 6 The information Gd is sequentially supplied to the latent image forming means 2, the latent image forming means 2 sequentially forms each divided latent image on the latent image carrier 1, and the developing means 3 successively supplies each divided latent image to the toner. Divided visual image formation control means 7 for developing and visualizing, and this divided visual image formation control And a divided visual image synthesizing control means 8 for controlling the transfer means 4 so that the toner images corresponding to the respective divided image information Gd formed by the means 7 are aligned and superimposed on the transfer medium 5. Features.

In such technical means, as the latent image carrier 1, a photosensitive member, a dielectric, or the like may be appropriately selected as long as it can carry an electrostatic latent image. It does not matter whether it is a drum shape or a belt shape. The latent image forming means 2 charges the latent image carrier 1 and forms the image information G on the charged latent image carrier 1 as long as it can form an electrostatic latent image on the latent image carrier 1. To form an electrostatic latent image with a light beam or an ion current corresponding to the current, or to directly write the electrostatic latent image by an ion current writing unit or the like without charging the latent image carrier 1. Etc. may be selected as appropriate. Further, for example, in a multi-color image forming apparatus, it is necessary to form an electrostatic latent image for each color component, but the latent image forming means 2 may be separately provided for each color component, or Latent image forming means 2
May be shared. Further, the developing means 3 may be used regardless of its developing method (contact, non-contact development, one-component development, two-component development, dry development, or wet development). A plurality of developing means 3 for each
May be provided individually, or a rotary type in which a plurality of developing units are rotatably incorporated may be provided. Furthermore, as the transfer unit 4, if the toner image carried on the latent image carrier 1 is transferred to the transfer medium 5, an electrostatic transfer system, a pressure transfer system, a heat transfer system, or the like is appropriately selected. I don't mind. The transfer means 4 can be said to transfer a toner image directly onto at least the transfer medium 5, but an image forming apparatus using an intermediate transfer body also includes this intermediate transfer body.

Further, the image dividing means 6 includes image information G so that no pixel adjacent in the main scanning direction exists.
The pixel group may be appropriately selected as long as the pixel group is divided into a plurality of pixels. Usually, the recording pixel group of the image information G having a predetermined high recording density D is divided into (D / number of divisions) at a low recording density. The division into the recording pixel group of the image information Gd is performed.
For example, if it is divided into two, it is divided into an odd-numbered pixel group and an even-numbered pixel group.
7... 3n-2 (n = 1...) Th pixel group,
5th, 8th... 3n-1 (n = 1...) Th pixel groups,
.., 3n (n = 1...) Th pixel group, and 4n−1 (n = 1.
..)-Th pixel group, 4n-2 (n = 1...) -Th pixel group, 4n-3 (n = 1...) -Th pixel group, 4n (n =
..) Pixel group. Further, the form of the image division is not limited to the above-described one. For example, the image information G of the recording density D is divided into two divided image information Gd of the recording density D / 4 and one division of the recording density D / 2. It may be divided into image information Gd.

As for the specific configuration of the image dividing means 6, if the pixel group can be divided based on a predetermined number of divisions, the original image information G is repeatedly supplied by the number of divisions. A pixel group corresponding to the divided image information Gd may be extracted at predetermined timing intervals. At this time, for example, if the image forming apparatus includes an image reading unit, the same document may be read and scanned a plurality of times by the image reading unit, and the image information G may be repeatedly supplied. From the viewpoint of shortening the processing time, it is preferable that the document information read by one scanning is stored in the storage unit 11 in advance, and the image information G from the storage unit 11 is repeatedly supplied.

In order to configure the image dividing means 6 in such an embodiment, for example, a storage means 11 for storing image information G corresponding to each pixel, and a pixel selecting means for generating a pixel selection signal corresponding to the number of image divisions The image processing apparatus includes a signal generation unit 12 and an image information selection unit 13 for selectively extracting image information of a pixel to be read from the storage unit 11 based on the pixel selection signal generated by the pixel selection signal generation unit 12. What should I do?

Further, in the image dividing means 6 of the above-described embodiment, the pixel selection signal from the pixel selection signal generating means 12 may be appropriately generated as long as it selects a pixel to be extracted. When the number of pixels matches the resolution (1/1 of the resolution of the image information G corresponds to the resolution of the divided image information Gd), from the viewpoint of easy generation of the pixel selection signal, For example, it is possible to intermittently generate a pixel take-out timing signal for each pixel interval corresponding to the number of image divisions, and to shift the pixel take-out timing signal position in the main scanning direction for each pixel at the time of forming each divided latent image. preferable.

Further, the image dividing means 6 may be uniquely configured according to one image dividing number. However, in consideration of usability, the image dividing number variable means for variably setting the image dividing number is set. 14, the image division number variable means 14
It is preferable that the division mode of the constituent pixel group of the image information G be made variable in accordance with the number of image divisions set in the above. In this case, for example, the number of image divisions can be selected according to the type of image, such as four divisions for a photographic image, two divisions for a character image, and three divisions for a mixture of both.

The divided visual image forming control means 7 and the divided visual image synthesizing control means 8 control the divided visual image forming step or the divided visual image synthesizing step in accordance with the image dividing mode. If appropriate, you can select it.

[0019]

The operation of the technical means described above is shown in FIGS.
It will be described based on. FIG. 3 is an operation explanatory view showing an example in which an image having a high recording density D is divided into two parts. FIG. 4 is a frequency response characteristic of an electrophotographic developing system (horizontal axis: spatial frequency of a latent image, vertical axis: ΔDout). (Output image contrast) / ΔDin
(Input image contrast)). The image dividing means 6 (see FIG. 1) divides a recording pixel group of an image having a recording density D into two. At this time, as shown in FIG. 3, each recording pixel of one divided image is located at a different position and between recording pixels of the other image. As a result, the recording density of each divided image becomes D / 2.

Thereafter, the divided visible image forming control means 7 (see FIG. 1) controls the latent image forming means 2 and the developing means 3 to form and develop a latent image for each of the divided images described above. A visible image (toner image) is formed. At this time, FIG.
As shown in the figure, at the recording density D, the developing system does not respond to the latent image, and cannot reproduce the dots and lines of the latent image faithfully. However, at the recording density D / 2, the developing system responds to the latent image. In order to faithfully reproduce the dots and lines of the latent image, as shown in FIG. 3, the divided visible images are obtained as good dots and lines.

Thereafter, the divided visual image synthesizing control means 8 (see FIG. 1) controls the transfer means 4 to transfer each divided visual image to the transfer medium 5.
Align and overlay on top. As a result, as shown in FIG. 3, each divided visual image is synthesized on the transfer medium 5, and the image of the original recording density D is restored. As described above, an image of high recording density with good reproducibility of dots and lines is obtained.

In the above description of the operation, a case where a high recording density image is divided into two parts is shown. However, it is a matter of course that the present invention is not limited to two divisions.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the embodiments shown in the accompanying drawings. First Embodiment FIG. 5 is an explanatory diagram showing a schematic configuration of a first embodiment of an image forming apparatus to which the present invention is applied. In FIG.
Denotes a photosensitive drum having a photosensitive layer formed on its surface, 21 denotes a charger for charging the photosensitive drum 20, 22 denotes a light beam scanning device that writes an electrostatic latent image on the charged photosensitive drum 20, and 23 denotes yellow and cyan. , Magenta, and black toners are provided, and the developing devices 23a to 23d are selectively set at developing positions opposite to the photosensitive drum 20 so that a latent image on the photosensitive drum 20 is formed. A rotary developing device that performs toner development, a recording drum 25 is wound around and held around the transfer drum, and a transfer drum that transfers the toner image on the photosensitive drum 20 to the recording paper 25, and a cleaning drum that cleans residual toner on the photosensitive drum 20 Cleaner 27 is photosensitive drum 2
Reference numeral 28 denotes a static elimination lamp for erasing residual charges on the recording paper 25, and a fixing device for fixing an unfixed toner image on the recording paper 25. still,
Reference numeral 29 denotes a paper feed cassette, and reference numeral 30 denotes a discharge tray.

Reference numeral 31 denotes a document reading device (scanner) for reading the document 32. The image data (image density signal (including a color component signal in the multi-color mode) of the document 32 read by the document reading device 31). ) Is temporarily stored in a memory (not shown) based on a command from the machine operation control CPU 70, and then stored in, for example, the light beam scanning device 22.
It is supplied to the image dividing device 80 incorporated in the side. Furthermore,
Reference numeral 100 denotes each image forming device (charging device 21, light beam scanning device 22, rotary developing device 23, transfer drum 24, cleaner 25, static elimination lamp 26, fixing device 28) based on a command from the machine operation control CPU 70. This is a process controller that controls driving.

More specifically, as shown in FIG. 6, for example, a light beam scanning device 22 according to this embodiment includes a semiconductor laser 221, a collimator lens 222 for collimating a beam 225 from the semiconductor laser 221; A polygon mirror 22 that moves and scans an incident beam 225 from a collimator lens 222 along the axial direction of the photosensitive drum 20
3 and an imaging lens 22 for imaging a beam 225 from the polygon mirror 223 on a scanning line of the photosensitive drum 20
And a scanning start signal generation sensor (SOS sensor) 226 for generating an SOS (Start of scanning) signal for detecting optical scanning start timing. In this embodiment, the photosensitive drum 2
0, the spot diameter of the light beam in the main scanning direction (1/1 /
e ² ) was set to 32 μm. Such a light beam scanning device 22 is a light beam scanning device according to a signal from the image dividing device.
25, the electrostatic latent image is formed by moving and scanning in the axial direction of the photosensitive drum 20 moving in the sub-scanning direction.

The rotary developing device 2 according to this embodiment
The developing devices 23a to 23d of No. 3 have an average developing carrier diameter 50 having a frequency response characteristic as shown in FIG.
A two-component developing system having an average toner diameter of 7 μm is used. Further, if the rotary developing device 23 is fixed to a plurality of latent images moving by the rotation of the photosensitive drum 20, the developing devices 23a to 23
A plurality of visible images are obtained with the same color toner of d.

Further, the transfer drum 24 used in this embodiment is a drum main body 2 around which a dielectric sheet is stretched.
41, a charging unit 242 for adsorbing paper at a portion corresponding to a supply unit of the recording paper 25 from the paper supply cassette 29 of the drum main body 241, a transfer charger 243 at a portion facing the photosensitive drum 20, and a recording paper 25. A sheet peeling charger 244 and a sheet removing claw 245 and a charge removing charger 246 for removing charges from the dielectric sheet of the drum main body 241 are provided immediately before the sheet peeling portion.

FIG. 7 shows the mutual relationship between the machine operation control CPU 70, the image dividing device 80, and the process controller 100 used in this embodiment. In the figure, reference numeral 61 denotes a start switch for starting an image forming operation, 62 denotes a switch group for selecting a color mode, and includes, for example, a monochrome black mode switch 62a and a full color mode switch 62b. Reference numeral 63 denotes a switch group for selecting the number of divisions of an image. For example, a two-part switch 63a selected for a character image, a four-part switch 63c selected for a photographic image, a character image, 3 selected when photographic images are mixed
A split switch 63b is included. Reference numeral 64 denotes a cycle sensor that generates a one-image forming cycle end signal each time the photosensitive drum 20 makes one rotation, for example.

The signals from the switches 61 to 63... And the cycle sensor 64 and the signal from the image reading device 31 are transmitted to the input interface 71 and the system bus 7.
The program is taken into the machine operation control CPU 70 via the CPU 2.
The machine operation control CPU 70 executes a control program stored in the ROM 73 in advance in accordance with the input signal, and temporarily stores image data from the image reading device 31 in the RAM 74, performs various operations, Alternatively, it reads out image data (image density signal) at a predetermined timing via the output interface 75 or sends out a predetermined control signal. At this time, an image density signal is sent to the image dividing device 80, and an image density signal CL which is a timing signal for sending the image density signal is sent to the image dividing device 80.
K and a CLK selection signal for selecting a timing signal CLK generated by dividing the image density signal CLK are transmitted as control signals. The process controller 10
A control signal for each image forming device is sent to 0. For example, the process controller 100 rotates and stops the rotary developing device 23 based on a developing process control signal of the machine operation control CPU 70, and develops the electrostatic latent image with a desired color toner.

FIG. 8 shows the details of the image dividing device 80 used in this embodiment. In the figure, an image dividing device 80 includes a CLK generation circuit 81, a CLK selection circuit 82,
It comprises an image density signal selection circuit 83, a D / A converter 84, a triangular wave oscillator 85 and a comparator 86. In this embodiment, the image dividing device 80 includes the document reading device 31.
Is divided into a plurality of pixel groups having a low recording density, and the semiconductor laser 221 of the light beam scanning device 22 is turned on and off in accordance with the image density signal of the divided pixel group.

More specifically, the CLK generation circuit 81 appropriately divides the frequency of the image density signal CLK of 400 spi synchronized with the image density signal of 8 bits (256 gradations).
A plurality of timing signals CLK for selecting an image density signal are generated. In this embodiment, CLK200-1 and CLK2 are used to divide the recording density of the 400 spi pixel group into two.
00-2, and the recording density of the pixel group of 400 spi is 3
CLK133-1, CLK133-2 for dividing,
CLK133-3, and CLK100-1 and CLK10 for dividing the recording density of the pixel group of 400 spi into four.
Nine types of timing signals CLK are generated in all of 0-2, CLK100-3, and CLK100-4.

Here, CLK200-1, CLK200
-2 high level outputs are generated at different pixel locations and between the other CLKs. In addition, CLK133-1, CLK133-2, CL
The high-level outputs of K133-3 are generated at different pixel positions and at positions shifted by one pixel. Further, CLK100-1, CLK1
The high-level outputs of 00-2, CLK100-3, and CLK100-4 are at different pixel positions and
It is generated so as to be located at a position shifted by each pixel.

Further, in this embodiment, the machine operation control CPU 70 has a switch group 6 for selecting the number of divisions of an image.
3, for example, if the two-part switch 63a is on,
Transmitting a CLK selection signal (for example, “0001,0010”) for sequentially selecting the CLK200-1 and CLK200-2;
If the three-part switch 63b is turned on, the above-mentioned CLK133-1, CLK133-2, CLK133-
3 is sequentially selected (for example, “0011,010”).
0,0101 "), and if the 4-split switch 63c is on, the CLK100-1 and CLK100
-2, CLK100-3, and CLK100-4 are sequentially selected (for example, “0111, 1000, 1001, 101
0 ").

Further, the CLK selection circuit 82 selects one timing signal CLK from the plurality of timing signals CLK generated by the CLK generation circuit 81 based on the CLK selection signal transmitted from the machine operation control CPU 70. .

Further, the image density signal selection circuit 83
The image density signal is selected by using the timing signal CLK selected by the CLK selection signal. In this embodiment, the image density signal is formed by an AND circuit that uses the timing signal CLK and the image density signal as input signals. Therefore, if 3
Assuming that the split switch 63b is turned on, the CLK selection circuit 82 outputs CLK133-1, CLK1
33-2 and CLK133-3 are sequentially selected. Now, assuming that the image density signal is “F0, E0, D0, C0, B0, A0, 90, 80,...”, The image density signal selection circuit 83 is selected when the CLK 133-1 is selected. , "F0,00,00, C0,00,00,90,00, ...
.. (See FIG. 8), selectively extract image density signals of the first, fourth, seventh,...
When 133-2 is selected, the image density signal selection circuit 83 outputs the second, fifth, eighth,..., "00, E0, 00, 00, B0, 00, 00, 80,. The image density signal of the pixel group is selectively extracted, and the image density signal selection circuit 83 further outputs “00,
00, D0,00,00, A0,00,00, ... "
... An image density signal of the 画素 th pixel group is selectively extracted.

Further, the selected image density signal is converted into an analog signal by a D / A converter 84,
The signal is input to the comparator 86 together with the triangular wave signal from 5. The comparator 86 compares the magnitude relationship between the image density signal and the triangular wave signal to generate a predetermined pulse width modulation signal (pulse width modulated image density signal). Semiconductor laser 2 of beam scanning device 22
21 is turned on and off.

Hereinafter, the image forming operation of this embodiment will be described with reference to FIG. FIG. 9 shows a case where an image having a recording density of 400 spi is recorded by dividing it into two to obtain a single color image using black toner. At this time, the operator
Monochromatic black mode switch 62a and two-part split switch 63a
Is selected, the start switch 61 is turned on.

Then, the machine operation control CPU 70 first reads the document 32 with the image reading device 31 and stores an image density signal corresponding to each pixel of the document in the RAM 74. Next, the machine operation control CPU 70 issues various commands to the process controller 100, rotates the rotary developing device 23 so that it can be developed with black toner, sets the black developing device 23d to the developing position, and To charge the photosensitive drum 20 (first visual image forming step 1). Thereafter, when the machine operation control CPU 70 issues a command to the image dividing device 80 to select CLK200-1, the image dividing device 80 takes in the image density signal of the pixel group stored in the RAM 74,
The LK 200-1 converts the image density signal into a recording density of 、, and sends the divided image density signal of, for example, an odd-numbered pixel group to the light beam scanning device 22.

Then, the light beam scanning device 22 performs exposure scanning to form a latent image having a recording density of 200 spi on the photosensitive drum 20 (first visual image forming step 2). Then, the formed latent image is moved by the rotation of the photosensitive drum 20, and is developed with the black toner of the black developing device 23d (first visual image forming step 3). At this time, the black developing device 2
Since the frequency response characteristic of 3d has the characteristic shown in FIG.
Since the pixel group has been converted to a recording density of ２, dots and lines are reproduced well.

The transfer drum 24 rotates while the recording paper 25 is mounted on the outer periphery, and the developed black toner image on the photosensitive drum 20 is transferred by the transfer charger 243 to the recording paper 25.
(First visual image forming step 4).

Next, the residual toner on the photosensitive drum 20 is removed by the cleaner 26, and the residual charge on the photosensitive drum 20 is removed by the charge removing lamp 27. Thereafter, the photosensitive drum again passes through the charger 21 and is initially charged, and returns to a state where a latent image can be formed (second visual image forming step 5).

On the other hand, when the photosensitive drum 20 makes one rotation, the cycle sensor 64 generates one image forming cycle end signal, which is taken into the machine operation control CPU 70.
Subsequently, the machine operation control CPU 70 controls the image dividing device 8
0 is instructed to select CLK200-2. Then, the image dividing device 80 takes in the image density signal of the pixel group stored in the RAM 74,
The image density signal is converted into a recording density of 1/2 by -2, and the divided image density signal of, for example, an even-numbered pixel group is sent to the light beam scanning device 22. Then, the light beam scanning device 22 performs exposure scanning to form a latent image with a recording density of 200 spi on the photosensitive drum 20 (second visual image forming step 6).

The formed latent image is transferred to the photosensitive drum 2
It is moved by the rotation of 0, and is developed with the black toner of the black developing device 23d which is fixed (second visual image forming step 7). At this time, the frequency response characteristic of the black developing device 23d has the characteristic shown in FIG.
Since the recording density is converted to 2, the dots and the lines are reproduced well.

The transfer drum 24 transfers the developed black toner image on the photosensitive drum 20 to the recording paper 25 by the transfer charger 243 (second visual image forming step 8), and the previously transferred black toner image Combine. At this time, CL
The pixel group selected by K200-1 and CLK200
Since the pixel group selected by -2 is located at a different position from each other and between the other CLKs, a line of black toner having a recording density of 400 spi is well reproduced on the recording paper 25. Image is obtained.

Thereafter, the recording paper 25 is peeled off by the peeling charger 244 of the transfer drum 24 and the paper peeling claw 245, and the unfixed toner image on the recording paper 25 is fixed by the fixing device 28 (fixing step 9). As described above, an image in which a line having a recording density of 400 spi is well reproduced on the recording paper 25 is obtained.

As described above, when a single-color image is obtained by dividing an image having a recording density of 400 spi into two, the photosensitive drum 20 and the transfer drum 24 may be rotated twice. When a multi-color image is obtained, the above-described single-color image forming operation is performed four times. That is, the photosensitive drum 20 and the transfer drum 24 are rotated eight times, and charging, exposure, development, and transfer to the recording paper 25 are performed eight times.
It may be performed twice.

An image having a recording density of 400 spi is 3
When a single color image is obtained by division, the photosensitive drum 20 and the transfer drum 24 are rotated three times, and charging, exposure, development, and transfer to the recording paper 25 are performed three times, so that each visible image of the same color is formed. What is necessary is just to combine it as one image on the recording paper 25. In this case, CLK 133-1, CLK 133-2, CLK 133-
3 are sequentially used. Further, when a multicolor image is obtained using four color toners, the single color image forming operation is performed four times. That is, the photosensitive drum 20 and the transfer drum 24 may be rotated 12 times, and charging, exposure, development, and transfer to the recording paper 25 may be performed 12 times.

Further, an image having a recording density of 400 spi is
When a single image is obtained by division, the photosensitive drum 20 and the transfer drum 24 are rotated four times, and latent image formation, development, and transfer to the recording paper 25 are performed four times, so that each visible image of the same color is formed. What is necessary is just to combine it as one image on the recording paper 25. In this case, CL for each rotation cycle
K100-1, CLK100-2, CLK100-3,
CLK100-4 are sequentially used. Further, when a multicolor image is obtained using four color toners, the single color image forming operation is performed four times. That is, the photosensitive drum 20 and the transfer drum 24 may be rotated 16 times, and charging, exposure, development, and transfer to the recording paper 25 may be performed 16 times.

Now, as a specific example of the image forming process, FIG.
(A) and (b). FIG. 10A is an enlarged view of an output image formed by dividing an image into two to obtain a first visualized image and a second visualized image, and then combining the images. FIG. 10B is an enlarged view of an output image obtained by dividing the image into three, obtaining first to third visualized images, and then combining the images.

Embodiment 2 This embodiment is different from Embodiment 1 in that, as shown in FIG. 11, each of the low-density visualized images is synthesized on the intermediate transfer member 33, To obtain an image having the original recording density. Note that components similar to those of the first embodiment are denoted by the same reference numerals as those of the first embodiment, and a detailed description thereof will be omitted.

The intermediate transfer member 33 used in this embodiment is composed of a dielectric belt 332 that is wrapped around a plurality of transport rolls 331 and rotates and has a transfer charger 333 at a position facing the photosensitive drum 20. Further, a pressure transfer roll 334 is disposed at a transfer portion on the recording paper 25 so as to be in pressure contact with the transport belt 331 so as to be separated from the dielectric belt 332. Reference numeral 34 denotes a cleaner for removing residual toner on the intermediate transfer member 33, and reference numeral 35 denotes an intermediate transfer member 3.
The recording paper 25 onto which the toner image has been transferred from
Transport belt for transport to

Next, an image forming operation according to this embodiment is shown in FIG. This figure shows a case where a 400 spi image is divided into two and a single color image is obtained by using black toner.

First, an image having a recording density of 400 spi is
When a single-color image is obtained by division, the same operation as in the first embodiment may be performed.
1. The image is divided into two by sequentially using CLK200-2, and the process controller 100
Each image forming device is controlled based on a command from U70.

That is, in FIG. 12, as the first visualized image forming step, first, the photosensitive drum 20 and the intermediate transfer member 33 are formed.
Is rotated once to charge the photosensitive drum 20 (step 1), expose the image divided by CLK200-1 by the light beam scanning device 22 (step 2), and develop by the black developing device 23d of the rotary developing device 23 (step 2). 3), transfer to the intermediate transfer body 33 (step 4) is performed. Next, as a second visual image forming step, the photosensitive drum 20 and the intermediate transfer member 33 are further rotated one turn, and the photosensitive drum 20 is charged (step 5), and the light beam scanning device 22 exposes the image divided by CLK200-2. (Step 6), development by black developing device 23d of rotary developing device 23 (Step 7), intermediate transfer body 3
3 (step 8), and a divided visible image (divided toner image) is synthesized on the intermediate transfer member 33. Thereafter, the composite visual image formed on the intermediate transfer body 33 is transferred onto the recording paper 25 at one time (step 9), and then fixed by the fixing device 28 (step 10).

As described above, an image on the recording paper 25 in which a line having a recording density of 400 spi was well reproduced was obtained. Further, the use of the intermediate transfer body 33 eliminates the need to suction and transport the sheet 25 as in the first embodiment,
It is possible to obtain an image in which a line is well reproduced even on a cardboard such as a postcard.

In the above embodiment, when a multicolor image is obtained with four color toners, this is achieved by performing the single color image forming operation four times. That is, the photosensitive drum 20 and the intermediate transfer body 33 are rotated eight times, and charged, exposed,
After the development and the transfer to the intermediate transfer member are performed eight times, the transfer to the recording paper 25 may be performed collectively.

An image having a recording density of 400 spi is
When a single-color image is obtained by division, the photosensitive drum 20 and the intermediate transfer body 33 are rotated three times, and charging, exposure, development, and transfer to the intermediate transfer body 33 are performed three times. The images may be combined on the intermediate transfer body 33 as one image, and then may be collectively transferred to the recording paper 25. In this case, CLK1 is used for each rotation cycle.
33-1, CLK133-2, and CLK133-3 are sequentially used. Further, when a multicolor image is obtained using four color toners, the single color image forming operation is performed four times. That is, the photosensitive drum 20 and the intermediate transfer body 3
3 for 12 rotations, charging, exposure, development and intermediate transfer
The transfer to the recording paper 25 may be performed 12 times, and thereafter, the transfer to the recording paper 25 may be performed at once.

An image having a recording density of 400 spi is
When a single color image is obtained by division, the photosensitive drum 20 and the intermediate transfer body 33 are rotated four times, and charging, exposure, development, and transfer to the intermediate transfer body 33 are performed four times, so that each of the same color images can be obtained. The images may be combined on the intermediate transfer body 33 as one image, and then may be collectively transferred to the recording paper 25. In this case, CLK1 is used for each rotation cycle.
00-1, CLK100-2, CLK100-3, CL
K100-4 is used sequentially. Further, when a multicolor image is obtained using four color toners, the single color image forming operation is performed four times. That is, the photosensitive drum 2
The charge transfer, the exposure, the development, and the transfer to the intermediate transfer body 33 are performed 16 times by rotating the intermediate transfer body 33 for 16 times, and then the batch transfer to the recording paper 25 may be performed.

Embodiment 3 This embodiment is different from Embodiments 1 and 2 in that, as shown in FIG. 13, each visualized image is synthesized on the photosensitive drum 20 and then transferred to the photosensitive drum 20 so as to face it. The charged image on the photosensitive drum 20 is collectively transferred onto the recording paper 25 by the charger 36,
The purpose is to obtain an image having a recording density. In this embodiment, the transfer charger 36 is provided on the back side of the transport belt 37 of the recording paper 25. Example 1,
The same components as those of the second embodiment are denoted by the same reference numerals as those of the first and second embodiments, and the detailed description thereof is omitted here.

Next, an image forming operation according to this embodiment is shown in FIG. This figure shows a case where a 400 spi image is divided into two and a single color image is obtained by using black toner.

In the figure, when an image having a recording density of 400 spi is divided into two to obtain a single color image, the first embodiment is used.
The same operation as described above may be performed.
The image is divided into two by sequentially using 200-1 and CLK200-2, and the process controller 100 controls each image forming device based on a command from the machine operation control CPU 70.

That is, in FIG. 14, as the first visualized image forming step, first, the photosensitive drum 20 is rotated once, the photosensitive drum 20 is charged (step 1), and the photosensitive drum 20 is divided by CLK200-1 by the light beam scanning device 22. Exposure to image (Step 2), black developing device 23 of rotary developing device 23
Development by d (step 3) is performed. Next, the transfer and cleaning are not performed, and while the developed image is held on the photosensitive drum 20, the photosensitive drum 20 is further moved as a second developed image forming step.
Rotate to charge the photosensitive drum 20 (Step 4), expose the image divided by CLK200-2 by the light beam scanning device 22 (Step 5), and develop by the black developing device 23d of the rotary developing device 23 (Step 6). Is performed to synthesize a divided visible image (divided toner image) on the photosensitive drum 20. Thereafter, the composite visual image formed on the photosensitive drum 20 is collectively transferred onto the recording paper 25 (Step 7), and thereafter, the fixing device 2
The fixing is performed at step 8 (step 8).

As described above, an image was obtained on the recording paper 25 in which a line having a recording density of 400 spi was well reproduced. In the present embodiment, since the transfer drum 24 and the intermediate transfer body 33 are not used, the size of the apparatus is reduced.

When a multicolor image is obtained with four color toners, the single color image forming operation is performed four times. That is, the photosensitive drum 20 is rotated eight times,
The charging, exposure, and development may be performed eight times, and then the batch transfer to the recording paper 25 may be performed.

Further, an image having a recording density of 400 spi is
When a single color image is obtained by division, the photosensitive drum 20 is rotated three times, and charging, exposure, and development are performed three times.
What is necessary is just to combine each visualized image of the same color on the photosensitive drum 20 as one image, and then to transfer it collectively to the recording paper 25. In this case, CL for each rotation cycle
K133-1, CLK133-2, and CLK133-3 are sequentially used. Further, when a multicolor image is obtained using four color toners, the single color image forming operation is performed four times. That is, the photosensitive drum 20 is rotated 12 times, and charging, exposure, and development are performed 12 times, and thereafter, the transfer is collectively transferred to the recording paper 25.

Further, an image having a recording density of 400 spi
When a single color image is obtained by division, the photosensitive drum 20 is rotated four times, and charging, exposure, and development are performed four times.
What is necessary is just to combine each visualized image of the same color on the photosensitive drum 20 as one image, and then to transfer it collectively to the recording paper 25. In this case, CL for each rotation cycle
K100-1, CLK100-2, CLK100-3,
CLK100-4 are sequentially used. Further, when a multicolor image is obtained using four color toners, the single color image forming operation is performed four times. That is, the photosensitive drum 20 is rotated 16 times, and charging, exposure, and development are performed 16 times.

Embodiment 4 Unlike Embodiments 1-3, this embodiment has a plurality of photosensitive drums 20a and 20b as shown in FIG. 14, and has a low recording density on each of the photosensitive drums 20a and 20b. The obtained visual image is formed, and an image having the original recording density is obtained on the recording paper 25 passed through the transfer position of each of the photosensitive drums 20a and 20b. This embodiment shows a case where an image of 400 spi is divided into two and a single color image is obtained using a predetermined color toner (for example, black toner).

More specifically, each photosensitive drum 2
0a and 20b, chargers 21a and 21b,
Light beam scanning devices 22a and 22b, developing devices 38a and 38b each containing a predetermined same color toner, transfer roll 3
9a and 39b, cleaners 26a and 26b, and static elimination lamps 27a and 27b are provided.
A paper transport belt 40 is provided along each transfer portion between the transfer rolls a and 20b and each of the transfer rolls 39a and 39b, and sucks and transports the recording paper 25.

Further, each of the light beam scanning devices 22a, 22
On the 2b side, image dividing devices 80a and 80b (specific configurations are similar to those of the first embodiment) are provided. In this embodiment, the original 32 read by the image reading device 31 is read.
For example, an image of 400 spi is directly transmitted to the respective image dividing devices 80a and 80b without going through a memory. Further, the machine operation control CPU 70 transmits the CLK2 signal to the CLK selection circuit 82 of the image splitting device 80a on the upstream side.
A command is issued to select 00-1 and CLK 20 is supplied to the CLK selecting circuit 82 of the downstream image dividing device 80b.
While giving an instruction to select 0-2, a process control signal to each image forming device is transmitted to the process controller 100.

Next, an image forming operation according to this embodiment is shown in FIG. In the figure, when a start switch (not shown) is turned on, the original 3
2 is performed, and 32 images of the document are transmitted to the image dividing devices 80a and 80b. Then, the upstream image dividing device 80a supplies the image density signal corresponding to the odd-numbered pixel group divided by the CLK 200-1 to the light beam scanning scan 22a, and the downstream image dividing device 8a.
0b denotes an image density signal corresponding to an even-numbered pixel group divided by CLK200-2, which is scanned by light beam scanning 22b.
Supply to

Therefore, in the photosensitive drum 20a on the upstream side,
Charging by the charger 21a (step 1), exposure by the light beam scanning device 22a (step 2), development by the developing device 38a (step 3), and transfer to the recording paper 25 (step 4) are performed.
Also, in parallel with the image formation by the upstream photosensitive drum 20a, the charger 21b is connected to the downstream photosensitive drum 20b.
(Step 1 '), exposure by the light beam scanning device 22b (Step 2'), and development by the developing device 38b (Step 3 '), and the recording paper 25 on which the visible image is transferred by the photosensitive drum 20a is transferred to the photosensitive drum. The visible image on the photosensitive drum 20b is transferred onto the recording paper 25 at the timing of passing through the transfer portion 20b (Step 5), and the divided visual images are synthesized on the recording paper 25. Thereafter, the visible image on the recording paper 25 is fixed by the fixing device 28 (Step 6).

As described above, an image was obtained on the recording paper 25 in which a line having a recording density of 400 spi was well reproduced. In this embodiment, the plurality of photosensitive drums 20a,
20b, the photosensitive drum 20 does not need to rotate a plurality of times as in the other embodiments, and high-speed operation is realized.

In this embodiment, when a multicolor image is to be obtained with four color toners, for example, the image read by the image reading device 31 is temporarily stored in a memory, and the image of each color component is stored in each image dividing device. 80a and 80b, and the developing units 38a and 38b are, for example, rotary developing devices.
What is necessary is just to adopt the method of superimposing the color component divided visible images on a and 20b. When the number of image divisions is made variable, third and fourth image forming units may be added to the first and second image forming units as shown in FIG. The image forming process may be variably set with the fifteen configuration.

Embodiment 5 In each of the above embodiments, the machine operation control CPU 70
Is such that the CLK selection signal is switched for each divided visualization cycle. In this embodiment, for example, the configuration is substantially the same as that of the first embodiment.
SO transmitted from the S sensor 226 (see FIGS. 6 and 7)
The S signal is fetched, and the CLK selection signal is switched for each scanning line number based on the count value of the counter, for example.

FIGS. 17 (a) to 17 (d) all show 400 s.
7A shows the switching state of the CLK selection signal when the pi image is divided into two parts. FIG. 7A shows a case where there is no switching for each scan, FIG.
(C) shows the case of switching every two scans, and (d) shows the case of switching every three scans.

Each recording pixel is located at a different position and between the recording pixels of other visible images.
An image in which a line having a recording density of 400 spi was well reproduced was obtained on the recording paper. In particular, in the present embodiment, the displacement of the recording pixels in the main scanning direction became less noticeable.

FIGS. 18A and 18B show a specific example of the image forming process of this embodiment. FIG. 18A is an enlarged view of an output image formed by switching the CLK selection signal for each scan to divide the image into two, thereby obtaining a first visualized image and a second visualized image, and then combining them. Show. FIG. 18 (b)
FIG. 3B is an enlarged view of an output image formed by switching the CLK selection signal for each scan to divide the image into three to obtain first to third visualized images and then combining them.

Embodiment 6 This embodiment corresponds to each of the above-described embodiments (pulse width modulation exposure).
In contrast to this, the tone reproduction of an image is performed by light intensity modulation exposure, and FIG. 19 shows a schematic configuration of an image dividing device 80. In the figure, an image dividing device 80 includes a CLK generation circuit 81, a CLK selection circuit 82, an image density signal selection circuit 83, and a D / A converter 84 similar to those in the first embodiment, but differs from the first embodiment. , The image density signal (analog signal) from the D / A converter 84 is input to the switching circuit 91, and the ON operation time of the switching circuit 91 is controlled in accordance with the image density signal to thereby control the current value from the constant current circuit 92. Is adjusted to change the current value for emission of the semiconductor laser 221.

As described above, a latent image is formed on the photosensitive drum 20 (20a, 20b in the type of the fourth embodiment) by light intensity modulation exposure with a reduced recording density. Is reproduced as a good visual image through the recording paper 2
On 5, an image in which dots of the original recording density were effectively reproduced was obtained. Further, in the present embodiment, a smooth image was obtained because it did not have the area gradation structure.

FIGS. 20 and 21 show a specific example of the image forming process of this embodiment. 20 and 21 each show an image divided into two parts. Here, FIG.
Means that the image is not changed every two scans without switching the CLK selection signal.
FIG. 3 is an enlarged view of an image obtained by dividing and performing light intensity modulation exposure to obtain a first visible image and a second development, and then to synthesize and form the image. Also, FIG. 20B shows that the image is divided into three parts without switching the CLK selection signal for each scan, and light intensity modulation exposure is performed.
FIG. 4 is an enlarged view of an image formed by obtaining a visualized image to a third visualized image and then combining them.

On the other hand, FIG.
FIG. 11 is an enlarged view of an image formed by switching a selection signal, dividing an image into two, performing light intensity modulation exposure, obtaining a first visualized image and a second visualized image, and then synthesizing the image. FIG. 21B shows an example in which the image is divided into three parts by switching the CLK selection signal for each scan.
FIG. 3 is an enlarged view of an image formed by performing light intensity modulation exposure to obtain first to third visible images and then combining and forming the images.

Embodiment 7 This embodiment relates to the light beam scanning device 22 of each of the above embodiments.
Instead of using the LED image bar (LED array) 41, FIG. 22 shows a schematic configuration of an image dividing device 80. Image dividing device 80 used in this embodiment
Includes a CLK generation circuit 81, a CLK selection circuit 82, and an image density signal selection circuit 83 similar to those in the first embodiment, and further includes an LED driver circuit 94 including a timing generator 93, a latch circuit, a current control circuit, and the like. ing.

Therefore, according to this embodiment, the image density signal (serial signal) selected by the image density signal selection circuit 83 is input to the timing generator 93 and is converted into a parallel signal for each scanning line. Each LED of the LED image bar 41 is transmitted to the driver circuit 94.
Controls on / off of the device.

As described above, each latent image is formed on the photosensitive drum 20 (20a, 20b in the fourth embodiment type) by the LED image bar 41 having a reduced recording density, and each latent image is developed by the developing process. After that, the image was reproduced as a good visible image, and an image in which dots and lines of the original recording density were well reproduced on the recording paper 25 was obtained. Further, in this embodiment, since the scanning optical system is not used, downsizing is realized.

[0085]

As described above, according to the present invention, a plurality of low recording density latent images are formed by dividing a recording pixel group of a high recording density image into a plurality of parts so that a developing system can respond. Then, after forming the respective visualized images, the respective visualized images are synthesized and restored to the original high-density image, so that the visualized image of each recorded pixel can be obtained within a sufficient range of the response of the developing system. Good reproduction can be achieved, and high recording density of an image can be easily realized.

Further, as the image dividing means, a pixel selection signal corresponding to the number of image divisions is generated, and the image information of each pixel stored in the storage means is selectively extracted based on the pixel selection signal. In addition, the image can be divided efficiently. In particular, upon generation of a pixel selection signal, a pixel extraction timing signal is generated intermittently at each pixel interval corresponding to the number of pixel divisions, and the pixel extraction timing signal position is set in the main scanning direction at the time of forming each divided latent image. If the pixel is shifted in units, the pixel selection signal can be easily and reliably generated.

Further, if an image division number variable means for variably setting the image division number is provided and the division mode of the constituent pixel group of the image information is made variable according to the set image division number, the character The number of image divisions can be selected according to the type of image, such as an image, a photographic image, or a mixed image of both, and image formation matching the type of image can be easily realized with the optimal number of image divisions. .

[Brief description of the drawings]

FIG. 1A is an explanatory diagram illustrating an image forming method according to the present invention, and FIG. 1B is an explanatory diagram illustrating a configuration of an image forming apparatus according to the present invention.

FIG. 2 is a graph illustrating frequency response characteristics of an electrophotographic developing system.

FIG. 3 is an explanatory diagram showing an image forming process according to the present invention.

FIG. 4 is an explanatory diagram showing a relationship between recording density and reproducibility in a development system frequency response characteristic.

FIG. 5 is an explanatory diagram illustrating a schematic configuration of the image forming apparatus according to the first embodiment.

FIG. 6 is an explanatory diagram illustrating a specific example of the light beam scanning device according to the first embodiment.

FIG. 7 is an explanatory diagram illustrating a machine operation control system according to the first embodiment.

FIG. 8 is an explanatory diagram illustrating an image division device according to the first embodiment.

FIG. 9 is an explanatory diagram illustrating an image forming process according to the first embodiment.

FIGS. 10A and 10B are explanatory diagrams illustrating a specific example of an image forming process according to the first embodiment. FIG. 10A illustrates a case of two divisions, and FIG. 10B illustrates a case of three divisions.

FIG. 11 is an explanatory diagram illustrating a schematic configuration of an image forming apparatus according to a second embodiment.

FIG. 12 is an explanatory diagram illustrating an image forming process according to the second embodiment.

FIG. 13 is an explanatory diagram illustrating a schematic configuration of an image forming apparatus according to a third embodiment.

FIG. 14 is an explanatory diagram illustrating an image forming process according to the third embodiment.

FIG. 15 is an explanatory diagram illustrating a schematic configuration of an image forming apparatus according to a fourth embodiment.

FIG. 16 is an explanatory diagram illustrating an image forming process according to the fourth embodiment.

FIGS. 17A and 17B are explanatory diagrams illustrating a CLK selection process of the image dividing apparatus used in the image forming apparatus according to the fifth embodiment. FIG. 17A illustrates a case where switching is not performed for each scan, and FIG. (C), when switching every two scans, (d)
Indicates a case where switching is performed every three scans.

FIGS. 18A and 18B are explanatory diagrams illustrating a specific example of an image forming process according to the fifth embodiment. FIG. 18A illustrates a case of two divisions, and FIG.

FIG. 19 is an explanatory diagram illustrating an image dividing device used in an image forming apparatus according to a sixth embodiment.

20A and 20B are explanatory diagrams illustrating a specific example of an image forming process according to the sixth embodiment. FIG. 20A illustrates a case of two divisions without switching for each scan of the CLK selection signal, and FIG. The case of three divisions without switching is shown.

FIGS. 21A and 21B are explanatory diagrams illustrating a specific example of an image forming process according to a sixth embodiment. FIG. 21A illustrates a case where the CLK selection signal is divided into two for switching each scan, and FIG. The case of switching into three divisions is shown.

FIG. 22 is an explanatory diagram illustrating an image dividing device used in the image forming apparatus according to the seventh embodiment.

FIG. 23 is an explanatory view showing a conventional image forming process.

[Explanation of symbols]

A: image dividing step, B: divided visual image forming step, C: divided visual image synthesizing step, G: image information, Gd: divided image information, 1 ...
Latent image carrier, 2 latent image forming means, 3 developing means, 4 transfer means, 5 transfer medium, 6 image dividing means, 7 divided divided image formation control means, 8 divided divided image synthesis control means , 11 ... storage means, 12 ... pixel selection signal generation means, 13 ... image information selection means, 14 ... image division number variable means

Continued on the front page (72) Inventor Takayuki Yamashita 2274 Hongo, Ebina-shi, Kanagawa Prefecture Fuji Xerox Co., Ltd. ) Inventor Masahiko Kubo 2274 Hongo, Ebina-shi, Kanagawa Fuji Xerox Co., Ltd. Ebina Works (56) References JP-A-5-61339 (JP, A) JP-A-5-138932 (JP, A) (58) Surveyed field (Int.Cl. ⁶ , DB name) B41J 2/44 G03G 15/04 111

Claims (5)

(57) [Claims] In an image forming method for forming a latent image on a latent image carrier based on image information and developing the latent image to visualize the image, there is no adjacent pixel in the main scanning direction. Image dividing step (A) for dividing the constituent pixel group of the image information (G) into a plurality as described above, and forming a latent image based on each divided image information (Gd) divided in the image dividing step (A). A divided visualized image forming step (B) for repeating development and forming a visualized image corresponding to each divided image information, and each divided image information (Gd) formed in the divided visualized image forming step (B). A divided visual image synthesizing step (C) of aligning and superimposing a visual image on a transfer medium. 2. A latent image forming means (2) for forming a latent image according to image information on a latent image carrier (1), and developing the latent image on the latent image carrier (1) with toner. An image forming apparatus comprising: a developing unit (3) for developing a toner image by a developing device; and a transfer unit (4) for transferring a toner image developed by the developing unit (3) to a transfer medium (5). Image dividing means (6) for dividing the constituent pixel group of the image information (G) into a plurality of pixels such that there is no pixel adjacent to the image information (G); and each divided image information ( Gd) is sequentially supplied to the latent image forming means (2), and the latent image forming means (2) sequentially forms each divided latent image on the latent image carrier (1), and supplies the latent image to the developing means (3). A divided visual image forming control means (7) for sequentially developing each of the divided latent images with toner to form a visualized image; Transfer medium the toner image corresponding to each divided image information formed by (7) (Gd) (5)
An image forming apparatus comprising: a divided visual image synthesizing control means (8) for controlling the transfer means (4) so as to be aligned and superimposed thereon. 3. The image dividing means according to claim 2, wherein said image dividing means comprises: memory means for storing image information corresponding to each pixel; and a pixel selection signal corresponding to the number of image divisions. A pixel selection signal generating means (12) for generating a pixel selection signal, and image information of a pixel to be read out from the storage means (11) based on the pixel selection signal generated by the pixel selection signal generating means (12). An image forming apparatus comprising: an image information selecting unit (13) to be taken out. 4. A pixel selection signal from a pixel selection signal generation means (12) according to claim 3, wherein a pixel extraction timing signal is generated intermittently at every pixel interval corresponding to the number of image divisions, and An image forming apparatus which shifts the pixel take-out timing signal position in the main scanning direction for each pixel at the time of forming each divided latent image. 5. The image dividing means (6) according to claim 2, wherein said image dividing means (6) has an image dividing number variable means (14) for variably setting an image dividing number.
Image information (G) corresponding to the number of image divisions set in 4)
An image forming apparatus characterized in that the mode of dividing the constituent pixel group is made variable.