JP3474666B2 - Image forming device - 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 apparatus suitable for a digital copying machine or the like, and more particularly to an image forming apparatus capable of obtaining a stable image.

[0002]

2. Description of the Related Art Generally, in an electrophotographic digital image forming apparatus, image information of a document (original image) is divided into minute pixels of about several tens of microns, and an electric signal (image) corresponding to the density of each pixel is generated. Signal) to a digital signal,
The digital image signal is internally processed and converted, and then output using a laser beam or the like to obtain an image through an electrophotographic process.

In such a digital image forming apparatus, the internal signal processing is often changed depending on the type of the input image. For example, when reproducing image data mainly composed of characters, the density of the characters and the color level of the background are not so important, and it is desired that the characters are sharply reproduced.

Therefore, in the case of a printer having only binary output and on output, the input image information is binarized at a fixed level to reproduce the image. On the other hand, when trying to reproduce the image data of an input image that has so-called gradation such as a photographic image, it is important to reproduce halftones, and the purpose of processing is different from the case of character-centered processing. come.

For example, in the case of a binary printer, a pseudo halftone image is formed by using a known method such as a dither method or a density matrix method, and the image is reproduced by using the output thereof.

FIG. 9 is a characteristic diagram showing the gradation characteristics as described above, and shows the relationship between the original image density OD and the output image density CD. As a general γ characteristic, a characteristic curve A in FIG. 9 is obtained in a copying machine that performs analog processing or a copying machine that does not perform special processing even if it is digital processing.

The reason for such characteristics is considered to be the characteristics of the photosensitive member and the fact that the toner dots spread and overlap adjacent dots during the course of various processes such as development and fixing.

In the case of the characteristic shown by the characteristic curve A, it is difficult to express gradation. Therefore,
Treat two dots (pixels) of the image data of the original image as one unit for image processing and image formation, and form an image by changing the area of dots made by toner within the area of these two dots. Thus, an image having excellent gradation characteristics is formed.

FIG. 10 is a diagram showing an example of an output image when 2 dots in the horizontal direction are treated as one unit in image formation for image data of 8 × 8 dots. As described above, by using 2 dots as one unit, the gradation characteristic is improved although the resolution is reduced in the horizontal direction. The gradation characteristic in such a case is shown by a characteristic curve B in FIG. Further, in such a case, dots formed by toner are overlapped in the vertical direction to form vertical lines.

By the way, in recent years, in order to improve the output speed of the image forming apparatus, a two-beam system in which two laser beams are simultaneously used is used as shown in FIG. As a result, two horizontal lines are always output at the same time,
The speed in the sub-scanning direction can be doubled without changing the rotation speed of the polygon mirror.

In this case, the two laser beams are aligned using a half mirror or a prism. Therefore, when this alignment is good, vertical lines as shown in FIG. 10 are formed.

[0012]

However, if a relative displacement occurs in the alignment of the two laser beams,
The image will be rough. FIG. 12 shows an example in which the two laser beams are displaced in the lateral (main scanning) direction.
Further, FIG. 13 shows an example in which the two laser beams are displaced in the vertical (sub-scanning) direction.

In the case of an image having a gradation in which such image roughness occurs, it may be unsightly depending on the direction and angle of the shift. The present invention has been made in view of the above problems, and an object of the present invention is to realize an image forming apparatus capable of stably forming an image having gradation.

[0014]

The inventor of the present application has conducted earnest research to improve various problems in the image forming apparatus which have been conventionally proposed, and as a result, the gradation is reproduced by a 2-dot image. The present invention has been completed by finding a new method of image formation that is not affected by the relative deviation of the laser beam in the laser beam image forming apparatus.

That is, the present invention, which is a means for solving the problems, and its preferable range are as described in the following (1) to (7). (1) A first means for solving the problem is an image forming apparatus having an optical system that uses a plurality of laser beams in the sub-scanning direction, in a state where the output of at least one of the plurality of laser beams is reduced. An image forming apparatus characterized by performing image formation.

(2) A second means for solving the problem is an image forming apparatus having an optical system which uses a plurality of laser beams in the sub-scanning direction, and outputs at least one of the plurality of laser beams to another output. 90% of laser beam output
The image forming apparatus is characterized by having control means for controlling the laser light source driving means so as to form an image in the following state.

(3) A third means for solving the problem is to stop the output of at least one of the plurality of laser beams in an image forming apparatus having an optical system that uses a plurality of laser beams in the sub-scanning direction. The image forming apparatus is characterized by having control means for controlling the laser light source driving means so as to form an image in this state.

(4) A fourth means for solving the problem is an image forming apparatus having an optical system which uses a plurality of laser beams in the sub-scanning direction, and outputs at least one of the plurality of laser beams to another output. An image forming apparatus characterized by having a control means for controlling the laser light source driving means so as to form an image in a state where the output of the laser beam is lower than that, and for controlling each part so as to change other image forming conditions. Is.

(5) A fifth means for solving the problem is an image forming apparatus having an optical system which uses a plurality of laser beams in the sub-scanning direction, and outputs at least one of the plurality of laser beams to another output. Control means for controlling the laser light source driving means so as to form an image in a state where the output of the laser beam is lower than that, and for controlling the laser light source driving means so as to form an image in a state where the output of another laser beam is raised. An image forming apparatus comprising:

(6) A sixth means for solving the problem is an image forming apparatus having an optical system that uses a plurality of laser beams in the sub-scanning direction, and outputs at least one of the plurality of laser beams to another output. An image forming apparatus characterized by having control means for controlling a laser light source driving means so as to form an image in a state where the output of the laser beam is lower than the output, and for controlling so as to change the rotation speed of the developer carrying member. Is.

(7) A seventh means for solving the problem is an image forming apparatus having an optical system which uses a plurality of laser beams in the sub-scanning direction, and outputs at least one of the plurality of laser beams to another output. An image forming apparatus comprising: a control unit that controls a laser light source driving unit so as to form an image in a state where the output is lower than a laser beam output, and a control unit that changes a developing bias voltage of a developing unit. is there.

[0022]

[Action]

(1) In the first means for solving the problem, when using a plurality of laser beams in the sub-scanning direction, image formation is performed in a state in which the output of at least one of the plurality of laser beams is reduced. .

(2) In the second means for solving the problem, when a plurality of laser beams are used in the sub-scanning direction,
The laser light source driving unit is controlled by the control unit so that the output of at least one of the plurality of laser beams is 90% or less of the output of the other laser beam, and image formation is performed.

(3) In the third means for solving the problem, when a plurality of laser beams are used in the sub-scanning direction,
The laser light source drive means is controlled by the control means so that the output of at least one of the plurality of laser beams is stopped, and image formation is performed.

(4) In the fourth means for solving the problem, when a plurality of laser beams are used in the sub-scanning direction,
An image is formed by controlling the respective units by the control unit so that the output of at least one laser beam among the plurality of laser beams is made lower than the output of other laser beams and other image forming conditions are changed.

(5) In the fifth means for solving the problem, when a plurality of laser beams are used in the sub-scanning direction,
The control means controls the laser light source driving means so that the output of at least one of the plurality of laser beams is lower than the output of the other laser beams and the image formation is performed in the state where the output of the other laser beams is increased. Image formation is performed.

(6) In the sixth means for solving the problem, when a plurality of laser beams are used in the sub-scanning direction,
The laser light source drive means is controlled by the control means so as to form an image in a state where the output of at least one of the plurality of laser beams is lower than the output of the other laser beams, and the rotation speed of the developer carrier is changed. Thus, the image formation is performed under the control of the control means.

(7) In the seventh means for solving the problem, when a plurality of laser beams are used in the sub-scanning direction,
The laser light source drive means is controlled by the control means so as to form an image in a state where the output of at least one of the plurality of laser beams is lower than the output of the other laser beams, and the developing bias voltage of the developing means is changed. Is controlled by the control means to perform image formation.

[0029]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a block diagram showing the arrangement of an image forming apparatus according to an embodiment of the present invention.

Then, FIG. 2 and subsequent figures are explanatory views showing an enlarged image of the image formed by this embodiment. Although the present invention can be applied to all image forming apparatuses that use a plurality of laser beams in the sub-scanning direction, the description will be given here using an apparatus that uses two laser beams.

<Structure of Image Forming Apparatus> In FIG. 1, an operation unit 1 is an input means for receiving various instructions from an operator, and for example, a photograph in which a character mode for outputting an image in which contrast is emphasized and a gradation characteristic is emphasized. It is configured to receive various instructions such as mode switching with a mode.

The control unit 2 controls the image forming apparatus as a whole, and in the present embodiment, gives various instructions to each unit in the photographic mode. The memory 3 is a storage unit that stores image data.

The data processing unit 4 is a processing means for dividing the image data read from the memory 2 into two systems so as to form an image with two laser beams in the sub-scanning direction.

The PWM modulation section 5 is a modulation means for generating a signal (PWM signal) having a pulse width corresponding to the density of each pixel of the image data, and includes the PWM modulation section 5a and the PWM modulation section 5.
It is composed of two systems, b.

The driver section 6 is a drive means for receiving a PWM signal and generating a drive current for driving the laser diode, and is composed of two systems, a driver section 6a and a driver section 6b.

The laser diode 7a is a light emitting means for generating a first laser beam by the drive current from the driver section 6a, and the laser diode 7b is a light emitting means for generating a second laser beam by the drive current from the driver section 6b. Is. The laser beams from these laser diodes 7a and 7b are scanned in the main scanning direction by scanning means such as a polygon mirror not shown in FIG.

The printer unit 8 forms a toner image on the image bearing member (photosensitive drum) by the above-mentioned first and second laser beams, transfers the toner image onto paper, and transfers the toner image on the paper. Is an image output means for fixing an image with heat or pressure to form an image. The printer unit 8 includes a half mirror 8a that combines the two laser beams so as to be adjacent to each other in the sub-scanning direction, mirrors 8b and 8c that guide the combined laser beam onto the image carrier, and a laser beam. It has a photosensitive drum 8d as an image bearing member on which an electrostatic latent image is formed, a developing unit 8e for developing the electrostatic latent image on the photosensitive drum 8d with toner, and the like.

<Operation of Image Forming Apparatus (1)> The operation of the image forming apparatus configured as described above will be described below, focusing on the operation in the photographic mode.

The processing modes of the image forming apparatus are roughly classified into a character mode for outputting an image with emphasis on contrast and a photographic mode with emphasis on gradation characteristics. The operator's instruction from the input means 1 or image data discrimination Depending on the result, mode switching is performed in the control unit 2.

In this embodiment, the operation in the photo mode will be described. This operation is as follows.
Each step will be described in order. Image data read: Image data stored in the memory 3 is read according to a read control signal and an address signal from the control unit 2.

Data division process: In order to form an image with two laser beams, the data processing unit 4 outputs the image data for two lines in the main scanning direction with the timing aligned with respect to the image data that is sequentially read. To do.

PWM modulation processing: In the photographic mode, two dots (pixels) are conventionally treated as one unit in the main scanning direction in order to attach importance to gradation characteristics. By doing so, the overlap between adjacent dots formed by the toner finally output is reduced in the main scanning direction, and the intermediate gradation is well reproduced. In this embodiment, the outputs of the laser beams adjacent to each other in the sub-scanning direction are changed so that they do not overlap in the sub-scanning direction, as described below. Therefore, in the main scanning direction, one pixel of the image data is treated as it is as one unit and the PWM modulation is executed.

Since the pulse width of the PWM signal generated by the selection of the threshold value in this PWM modulation is different, in the case of the photographic mode, the control unit 2 outputs P.
The thresholds of the WM modulators 5a and 5b are changed. For example, one of the thresholds is changed so that the output of one of the two laser beams is reduced.

The ratio of the decrease in the output of the laser beam will be described in detail in an experimental example described later, but the output of the original laser beam is set to 0% to 90%. Although the case of using two laser beams has been described here, the output of at least one of the plurality of laser beams may be adjusted even when more laser beams are used.

Laser beam output: The driver unit 6 generates respective drive currents by the PWM signal generated as described above, and the laser diodes 7a and 7b output two laser beams by the drive currents. . This laser beam produces an electrostatic latent image on the photosensitive drum 8d.

Development-Transfer: The electrostatic latent image on the photosensitive drum 8d is developed by the developing unit 8e to become a toner image. Then, the toner image is transferred and fixed by the transfer unit and the fixing unit to form an image on the paper.

<Evaluation of Formed Image> Here, the evaluation of the image quality of the image formed according to this embodiment will be performed in several cases.

LD7a = 100%, LD7b = 0% FIG. 2 is an enlarged view of an image formed when the output of one laser beam is 0%, and shows an 8 dot × 8 dot portion. .

In this case, since one pixel in the main scanning direction is treated as one unit and the adjacent laser beam in the sub scanning direction is stopped, an image is formed by a horizontal line instead of the conventional vertical line.

In this case, a horizontal line is used instead of the conventional vertical line, so that the conventional 200 dpi (main) × 400 dpi (sub)
The resolution was 400 dpi (main) x 200 dpi
Since it is (sub), there is no significant change in the resolution of the entire screen.

Further, since there is a blank portion due to the laser beam being stopped for each pixel in the sub-scanning direction, there is no dot overlap and the gradation characteristics are good. And
Since one of the laser beams is stopped, the image does not become rough due to the relative displacement between the two laser beams in the main scanning direction and the sub scanning direction.

FIG. 3 shows an image formed when the operating laser beam is slightly deviated in timing every scan. When such a shift occurs, the conventional problem was that the vertical lines were misaligned.
In this case, since it is a horizontal line, problems such as image roughness do not occur.

LD7a = 100%, LD7b = 1 to 90% FIG. 2 is an enlarged view of an image formed when the output of one laser beam is set to any of 1 to 90%, and is 8 dots × 8 dots. Is shown.

In this case, since one pixel in the main scanning direction is treated as one unit and the output of the laser beam adjacent in the sub scanning direction is reduced, instead of the conventional vertical line, the horizontal line and the horizontal line overlap each other. An image is formed with independent dots that do not match.

In this case, the horizontal lines + independent dots are used instead of the conventional vertical lines, so that the conventional 200 dpi × 400 dpi
The resolution that was (sub) is 400 dpi (main) x 400d
Since it is pi (sub), the resolution of the entire screen is improved.

Further, since there is a blank portion due to the reduction of the laser beam output for each pixel in the sub-scanning direction, there is no dot overlap and the gradation characteristics are good. Since the output of one of the laser beams is reduced, even if a relative displacement between the two laser beams in the main scanning direction and the sub-scanning direction occurs, the displacement does not roughen the image.

FIG. 4 shows an image formed when the timings of the two laser beams are slightly deviated in the main scanning direction. Even if such a shift occurs, the horizontal lines and the independent dots do not cause a shift or overlap between the dots, and a problem such as image roughness does not occur.

FIG. 5 shows an image formed when the timings of the two laser beams are relatively deviated in the sub-scanning direction. Even if such a shift occurs, the horizontal lines and the independent dots do not cause a shift or overlap between the dots, and a problem such as image roughness does not occur.

Effect of Laser Beam Output on Image Quality An experiment was conducted on the relationship between the output ratio (reduced output / output before reduction) and image quality when the output of one laser beam was reduced as described above. As a result, the following results were obtained.

[0060]

[Table 1]

As shown in Table 1, it was confirmed that a relatively good image can be obtained by setting the output of either one of the laser beams to 90% or less. It was also confirmed that a better image can be obtained by setting the output of either one of the laser beams to 85% or less. It was confirmed that even better images can be obtained by setting (stopping) the output of either one of the laser beams to 0%.

The image formation in this case was performed under the conditions shown in Table 2 below.

[0063]

[Table 2]

The conditions of the fixing device and the developer were as follows.・ Fixer [Upper roller] Length: 324mm Diameter: φ50mm Core material: PFA coating 20μm [Lower roller] Length: 310mm Diameter: φ50mm Core material: LIV rubber 5mm (rubber hardness 30 °) + PFA
Tube 70 μm [Load] 3.7 kgf / cm [Heater] Upper roller: 1100 W Lower roller: 200 W ・ Developer [toner] Material: Polyester diameter: Average particle diameter 8.5 μm [Carrier] Material: Ferrite resin coating diameter: Average particle size 60 μm [Density] 6 wt% <Operation of image forming apparatus (2)> Comparing the conventional photographic mode using vertical lines with the photographic mode of the above operation (1), one can be seen in operation (1). Since the laser beam is stopped or the output is reduced, it has a characteristic that the concentration becomes low.

FIG. 6 is a characteristic diagram showing a density characteristic, a curve a shows the density characteristic in the photographic mode by the conventional apparatus, and a curve b shows one laser beam in the photographic mode in the above operation (1). It shows the concentration characteristics when the is stopped. In this way, the density is slightly lower than 2
This is caused by stopping one of the laser beams of the book.

Therefore, by increasing the output of the remaining laser beam, the density can be increased while leaving the advantage that the image can be prevented from being roughened. In this case, the control unit 2 gives an instruction to the PWM modulation unit 5 or the driver unit 6 to increase the drive current supplied to one of the laser diodes.

The characteristic curve c shown in FIG. 7 is LD7a = 1.
80% (1.8 times that of the prior art) and LD7b = 0% are shown. By doing so, the maximum density could be made the same as the conventional one.

The characteristic curve d shown in FIG. 8 shows the case where the number of revolutions of the developer carrying member (developing sleeve) in the developing unit 8e is 1.6 times the normal number. Also in this case, the maximum density could be made the same as the conventional one by improving the developing characteristics.

Similarly, by changing the developing bias voltage of the developing unit 8e, the developing characteristics can be improved and the maximum density can be made the same as the conventional one. These cases can also be realized by giving an instruction from the control unit 2 to the printer unit 8.

[0070]

According to the present invention, in an image forming apparatus having an optical system that uses a plurality of laser beams in the sub-scanning direction, image formation is performed with the output of at least one of the plurality of laser beams reduced. By carrying out the above, it was possible to realize an image forming apparatus capable of stably forming an image having gradation.

By setting the output of at least one of the plurality of laser beams to 90% or less, preferably 85% or less, and more preferably 0% of the output of the other laser beams, gradation is stably reproduced. We were able to.

When controlling the output of the laser beam as described above, the image is stably reproduced by changing other image forming conditions, the number of revolutions of the developer carrier, the voltage of the developing bias, and the like. At the same time, it has become possible to satisfactorily form a high-density image. Further, by increasing the output of the laser beam that does not decrease the output as compared with the conventional case, it has become possible to satisfactorily form a high density image in the high density region.

[Brief description of drawings]

FIG. 1 is a configuration diagram illustrating a configuration of an image forming apparatus according to an exemplary embodiment of the present invention.

FIG. 2 is an explanatory view showing an enlarged image formed according to an embodiment of the present invention.

FIG. 3 is an explanatory diagram showing an enlarged image formed by an embodiment of the present invention.

FIG. 4 is an explanatory view showing an enlarged image formed by an embodiment of the present invention.

FIG. 5 is an explanatory view showing an enlarged image formed by an embodiment of the present invention.

FIG. 6 is a characteristic diagram showing density characteristics of an image formed according to an embodiment of the present invention.

FIG. 7 is a characteristic diagram showing density characteristics of an image formed according to an embodiment of the present invention.

FIG. 8 is a characteristic diagram showing density characteristics of an image formed according to an embodiment of the present invention.

FIG. 9 is a characteristic diagram showing density characteristics of an image formed in a character mode and a photographic mode.

FIG. 10 is an enlarged view showing an image formed in a photographic mode of a conventional apparatus.

FIG. 11 is an explanatory diagram showing a scanning state of an image forming apparatus having an optical system that uses a plurality of laser beams in a sub-scanning direction.

FIG. 12 is an enlarged view showing a case where a laser beam is displaced in an image formed in a photographic mode of a conventional apparatus.

FIG. 13 is an explanatory diagram showing, in an enlarged manner, a case where a laser beam is displaced in an image formed in a photographic mode of a conventional apparatus.

[Explanation of symbols]

1 Operation part 2 control unit 3 memory 4 Data processing unit 5 PWM modulator 6 Driver part 7a, 7b Laser diode 8 Printer section

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshiko Matsuoka 2970 Ishikawa-cho, Hachioji-shi, Tokyo Konica Corporation (56) References JP-A-3-238967 (JP, A) JP-A-3-216680 (JP , A) JP-A 1-224780 (JP, A) JP-A 4-264466 (JP, A) JP-A 5-257356 (JP, A) JP-A 5-318818 (JP, A) JP-A 6-109994 (JP, A) JP 6-91926 (JP, A) JP 5-167809 (JP, A) JP 2-110424 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B41J 2/44 G02G 21/00 370 G03G 15/04-15/04 120

Claims (7)

(57) [Claims] 1. An image forming apparatus having an optical system using a plurality of laser beams in a sub-scanning direction, wherein a character mode and a gradation characteristic, which emphasize a contrast, are emphasized.
The control means for distinguishing between the photo mode and the main mode is used when the image is formed in the photo mode.
Treats one pixel of image data as one unit in the scanning direction
There, in Rukoto reduces the output of the at least one laser beam of the plurality, dots heavy adjacent in the main scanning direction
Dots that are adjacent to each other in the sub-scanning direction
Make sure that the laser light source drive hands so that images are formed without overlapping.
An image forming apparatus characterized by controlling steps . 2. An image forming apparatus having an optical system using a plurality of laser beams in a sub-scanning direction, wherein a character mode and a gradation characteristic, which emphasize a contrast, are emphasized.
The control means for distinguishing between the photo mode and the main mode is used when the image is formed in the photo mode.
Treats one pixel of image data as one unit in the scanning direction
By setting the output of at least one of the plurality of laser beams to 90% or less of the output of other laser beams ,
Adjacent dots in the main scanning direction overlap and sub scanning
Image in which dots adjacent to each other do not overlap independently
An image forming apparatus, characterized in that a laser light source driving unit is controlled to perform formation. 3. An image forming apparatus having an optical system using a plurality of laser beams in the sub-scanning direction, wherein a character mode and a gradation characteristic, which place importance on contrast, are emphasized.
The control means for distinguishing between the photo mode and the main mode is used when the image is formed in the photo mode.
Handling one pixel of image data as one unit 査direction
By stopping the output of at least one of the multiple laser beams , adjacent dots in the main scanning direction will overlap.
Dots that are adjacent to each other in the sub-scanning direction
Make sure that the laser light source drive hands so that images are formed without overlapping.
An image forming apparatus characterized by controlling steps . 4. An image forming apparatus having an optical system using a plurality of laser beams in a sub-scanning direction, wherein a character mode and a gradation characteristic, which emphasize a contrast, are emphasized.
The control means for distinguishing between the photo mode and the main mode is used when the image is formed in the photo mode.
Treats one pixel of image data as one unit in the scanning direction
The main run is achieved by lowering the output of at least one of the multiple laser beams compared to the output of other laser beams.
Adjacent dots in the scanning direction overlap and the sub-scanning direction
An image forming apparatus, characterized in that the laser light source driving means is controlled so as to form an image independently of dots adjacent to each other, and each part is controlled so as to change other image forming conditions. 5. An image forming apparatus having an optical system that uses a plurality of laser beams in the sub-scanning direction, wherein the character mode and the gradation characteristics, which emphasize the contrast, are emphasized.
The control means for distinguishing between the photo mode and the main mode is used when the image is formed in the photo mode.
Treats one pixel of image data as one unit in the scanning direction
There, the output of at least one laser beam of the plurality with lowering the output of the other laser beam, in Rukoto increase the output of the other laser beam, in a main scanning direction
Adjacent dots overlap and are adjacent in the sub-scanning direction.
The image forming apparatus is characterized in that the laser light source driving means is controlled so that the dots are independently formed without overlapping . 6. An image forming apparatus having an optical system using a plurality of laser beams in a sub-scanning direction, wherein a character mode and a gradation characteristic, which emphasize a contrast, are emphasized.
The control means for distinguishing between the photo mode and the main mode is used when the image is formed in the photo mode.
Treats one pixel of image data as one unit in the scanning direction
There, the output of at least one laser beam of the plurality in Rukoto reduce the output of the other laser beams, the main run
Adjacent dots in the scanning direction overlap and the sub-scanning direction
Controls the laser light source driving means so as to perform image formation while the adjacent dots do not overlap independently of, control to change the rotation speed of the developer carrying member, that the image forming apparatus according to claim. 7. An image forming apparatus having an optical system that uses a plurality of laser beams in a sub-scanning direction, wherein a character mode and a gradation characteristic, which emphasize a contrast, are emphasized.
The control means for distinguishing between the photo mode and the main mode is used when the image is formed in the photo mode.
Treats one pixel of image data as one unit in the scanning direction
There, the output of at least one laser beam of the plurality in Rukoto reduce the output of the other laser beams, the main run
Adjacent dots in the scanning direction overlap and the sub-scanning direction
Controls the laser light source driving means so as to perform image formation while the adjacent dots do not overlap independently of controls to change the developing bias voltage of the developing means, that the image forming apparatus according to claim.