JP2001147563A - Image forming method and device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming method by which image density easily and surely corresponding to even the soil correction of a laser writing system, the change of a developing property and the changeover of resolution can be obtained, the consumption of toner can be freely stabilized or reduced and image quality can be changed to the desired one. SOLUTION: By this image forming method, a developed image is obtained by forming electrostatic latent images corresponding to image information with plural kinds of resolution on a photoreceptor by laser beams and developing them. Then, the image patch of prescribed picture element density is formed on the photoreceptor by changing the output of the laser beams every resolution and developed. Besides, the density of the developed image patches is detected. Based on the detected density detection information, the output of the laser beam that the image patch of the prescribed picture element density becomes the prescribed density is obtained. By the obtained output of the laser beam, the image of every resolution is formed.

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 an image forming method for obtaining a stable high-quality image for each resolution and an image under an arbitrary density condition by adjusting the output of a laser beam of an image forming apparatus having a laser exposure system. The present invention relates to a forming apparatus. The resolution is represented by the number of identifiable dots lined up per 25.4 mm in length, and this number is defined as dpi.

[0002]

2. Description of the Related Art In Japanese Patent No. 2746942, each level signal of a reference pattern and a pattern not to be visualized in a main scanning line is detected on a photosensitive member and a ratio thereof is obtained.
Compute and compare which rank the ratio value belongs to,
A difference from a preset reference value is determined according to the rank, and the width of one line of a laser beam output from an LD (laser diode) is corrected. However, this has the following disadvantages.

That is, the one line forms a black and white line pair by a scanning line and a white portion between the scanning lines. In this line pair, the line width in the sub-scanning direction can be clearly detected. In the line width (spot width) in the main scanning direction, the spots are continuously connected on the line, and it is substantially impossible to detect the spot width in that direction. Therefore,
It is not possible to correct the density by changing the line width.
The density adjustment by changing the line width can be performed by both the pulse width modulation method (PWM) and the power modulation. However, for the above-described reasons, the accuracy is inaccurate and involves considerable difficulty.

In Japanese Patent Application Laid-Open No. 07-25063, a plurality of lasers are independently driven in odd and even rows to form a prescribed image density, and the density of each laser is detected and compared. Adjusted to match the level. However, this has the following disadvantages.

That is, by comparing the image densities of a plurality of laser beam outputs and adjusting the power, it is possible to equalize the densities of the individual lasers. However, various factors such as the sensitivity of the photoreceptor and the physical properties of the toner are obtained. As the conditions change over time,
The actually obtained image density changes, and such a change over time cannot be corrected.

Further, in Japanese Patent Application Laid-Open No. 61-189575,
Means for creating a halftone image and visualizing it, detecting the density with a sensor, and corresponding to the detected density, the laser emission intensity (the LD output, since the laser is a light emitting diode,
LD power). However, this has the following disadvantages.

That is, the generated halftone is formed by pulse width modulation, and its density is adjusted by adjusting the LD power. In this case, the halftone density of the image drawn by pulse width modulation can be corrected by increasing or decreasing the LD power, but it is formed by 1-bit dots corresponding to the dots created with the maximum value of pulse width modulation. The density of the image in the high density area is changed by changing the LD power as described above.
It is highly likely that the value will change to a value different from the desired value.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to eliminate the above-mentioned drawbacks of the prior art and to provide an image forming method and an image forming apparatus which solve the following problems. I do.

(1) The density and density of an image formed by 1-bit halftone dots are defined by the density of a halftone dot pattern of an image patch. , The halftone density changes, and the amount of toner consumed for forming an image per sheet also changes. Therefore, such a phenomenon is prevented from occurring. That is, by controlling the diameter of the dot to be constant, 1
It is possible to stabilize the halftone density in an image formed by bit halftone dots and to keep the toner consumption constant.

(2) The dot diameter of a 1-bit image varies depending on the sensitivity of the photosensitive member and the variation in adjustment of the writing system, and changes over time due to fluctuation factors such as contamination of the laser system and deterioration of the developer. Avoid these effects.

(3) Writing system is 400 dpi / 600
Since the diameter of the laser dot differs depending on the resolution such as dpi and it is necessary to optimize each dot, the switching can be performed smoothly, accurately and easily.

(4) It is certain that the dot diameter is controlled for each resolution of 400 dpi / 600 dpi, but it is desirable to reduce toner consumption when creating an image patch.
There is a demand for saving the time required for correction, etc. To realize this, only one of the corrections is performed on the image patch created on the photoconductor, and the other correction is the former, which has been experimentally accumulated in advance. This can be performed by inputting a difference between the correction amount and the correction amount.

(5) Further, once the value of the dot diameter is fixed, a thicker character image or an oppositely thinner character image, that is, a toner consumption amount is increased due to a user's request for use or discretion at the discretion. Also, it is possible to easily set a dot diameter with a high image density and a dot diameter with a reduced toner consumption.

[0014]

This object is achieved by any of the following technical means (1) to (12).

(1) In an image forming method for forming an electrostatic latent image corresponding to image information at a plurality of resolutions on a photosensitive member by a laser beam and developing the electrostatic latent image to obtain a visible image, Changing the output of the laser beam to form an image patch having a specified pixel density on the photoconductor, developing the image patch, detecting the density of the developed image patch, and detecting the detected density. Based on the detection information,
An image forming method comprising: obtaining an output of a laser beam at which an image patch having a specified pixel density has a specified density; and forming an image for each resolution with the obtained output of the laser beam.

(2) In an image forming method of forming an electrostatic latent image corresponding to image information at a plurality of resolutions on a photosensitive member by a laser beam and developing the electrostatic latent image to obtain a visible image, In the resolution, the output of the laser beam is changed, an image patch having a specified pixel density is created on the photoconductor, the image patch is developed, and the density of the developed image patch is detected. Based on the detection information, an output of a laser beam at which an image patch of a specified pixel density has a specified density is obtained, an image is formed with the obtained output of the laser beam, and the laser beam of another resolution is obtained. An image forming method, wherein an offset value is adjusted with respect to the output of the laser beam, and an image of another resolution is formed with the laser output value adjusted with the offset value.

(3) In an image forming method for forming an electrostatic latent image corresponding to image information at a plurality of resolutions on a photoreceptor by a laser beam and developing the electrostatic latent image to obtain a visible image, In each, by changing the output of the laser beam, create an image patch of a specified pixel density on the photoconductor, detect the potential of the image patch on the photoconductor, based on the detected potential detection information An image forming method for obtaining an output of a laser beam so that an image patch having a specified pixel density has a specified potential, and forming an image for each resolution with the obtained output of the laser beam.

(4) In an image forming method of forming an electrostatic latent image corresponding to image information at a plurality of resolutions on a photosensitive member by a laser beam and developing the electrostatic latent image to obtain a visible image, In the resolution, by changing the output of the laser beam, create an image patch of a specified pixel density on the photoconductor, detect the potential of the image patch on the photoconductor,
Based on the detected potential detection information, an output of a laser beam is obtained so that an image patch of a specified pixel density has a specified potential, an image is formed with the obtained output of the laser beam, and a laser beam of another resolution is formed. An image forming method, wherein an offset value is added to or subtracted from the obtained laser beam output, and an image of another resolution is formed with the laser output value obtained by adding or subtracting the offset value.

(5) In an image forming apparatus which forms an electrostatic latent image corresponding to image information at a plurality of resolutions on a photosensitive member by a laser beam and develops the electrostatic latent image to obtain a visible image, Image patch creating means for creating an image patch having a specified pixel density on the photoreceptor by changing the output of the laser beam, developing means for developing the image patch, and density of the developed image patch. Detecting means for detecting a laser beam having an image patch of a specified pixel density having a specified density based on the density detection information from the density detecting means. An image forming apparatus for forming an image for each resolution by beam output.

(6) In an image forming apparatus for forming a latent image by forming an electrostatic latent image corresponding to image information with a plurality of resolutions by a laser beam on a photoreceptor and developing the electrostatic latent image to obtain a visible image, In the resolution, by changing the output of the laser beam, an image patch creating means for creating an image patch of a specified pixel density on the photoconductor, a developing means for developing the image patch, and a density of the developed image patch Density detecting means for detecting, an output adjusting means for obtaining an output of a laser beam at which an image patch of a specified pixel density has a specified density based on density detection information from the density detecting means, and an output of the obtained laser beam. Resolution converting means for forming an image and adjusting the offset value with respect to the laser beam output obtained for a laser beam having a different resolution; An image forming apparatus for forming an image of another resolution with the laser output value. (7) In an image forming apparatus which forms an electrostatic latent image corresponding to image information at a plurality of resolutions on a photoreceptor by a laser beam and develops the electrostatic latent image to obtain a visible image, Image patch creating means for creating an image patch of a specified pixel density on the photoreceptor by changing the output of the laser beam, potential detecting means for detecting the potential of the image patch, and potential detection from the potential detecting means Output adjustment means for obtaining an output of a laser beam at which an image patch of a specified pixel density has a specified potential based on the information, and forming an image for each resolution with the obtained output of the laser beam. Characteristic image forming apparatus.

(8) In an image forming apparatus which forms an electrostatic latent image corresponding to image information with a plurality of resolutions on a photoreceptor by a laser beam and develops the electrostatic latent image to obtain a visible image, In the resolution, an image patch creating unit that creates an image patch of a specified pixel density on the photoconductor by changing the output of the laser beam, a potential detecting unit that detects the potential of the image patch, and the potential detecting unit. Output adjustment means for obtaining an output of a laser beam at which an image patch having a specified pixel density has a specified potential based on the potential detection information of the above, forming an image with the output of the obtained laser beam, and forming a laser beam of another resolution A resolution conversion unit for adjusting an offset value with respect to the obtained laser beam output, and forming an image of another resolution with the laser output value adjusted for the offset value. An image forming apparatus characterized by forming.

(9) In an image forming method for forming an electrostatic latent image corresponding to image information at a plurality of resolutions on a photosensitive member by a laser beam and developing the electrostatic latent image to obtain a visible image, By changing the output of the beam, an image patch of a specified pixel density is created on the photoreceptor, the image patch is developed, the density of the developed image patch is detected, and based on the detected density detection information. Calculating the output of the laser beam at which the image patch of the specified pixel density has the specified density, adjusting the offset value with respect to the obtained output of the laser beam,
An image forming method comprising: forming an image under an arbitrary density condition by using a laser output value obtained by adding or subtracting the offset value.

(10) forming an electrostatic latent image corresponding to image information at a plurality of resolutions on a photosensitive member by a laser beam;
In the image forming method for developing a latent image by developing the electrostatic latent image, an image patch having a specified pixel density is formed on the photoconductor by changing an output of the laser beam, and the image patch on the photoconductor is formed. , Based on the detected potential detection information, obtain the output of the laser beam so that the image patch of the specified pixel density becomes the specified potential, add or subtract the offset value with respect to the obtained output of the laser beam, An image forming method comprising: forming an image under an arbitrary density condition by using a laser output value obtained by adding or subtracting the offset value.

(11) An electrostatic latent image corresponding to image information at a plurality of resolutions is formed on a photosensitive member by a laser beam,
In an image forming apparatus for developing a latent image by developing the electrostatic latent image, an image patch creating means for creating an image patch of a specified pixel density on the photoreceptor by changing the output of the laser beam; Developing means for developing the patch; density detecting means for detecting the density of the developed image patch; and a laser beam having an image patch of a specified pixel density having a specified density based on density detection information from the density detecting means. Output adjusting means for obtaining the output, and means for adjusting the offset value with respect to the output of the obtained laser beam, and forming an image under an arbitrary density condition with the laser output value adjusted for the offset value. Characteristic image forming apparatus.

(12) forming an electrostatic latent image corresponding to image information at a plurality of resolutions on a photosensitive member by a laser beam;
In an image forming apparatus for developing a latent image by developing the electrostatic latent image, an image patch creating means for creating an image patch of a specified pixel density on the photoreceptor by changing the output of the laser beam; Potential detecting means for detecting a potential of the patch; output adjusting means for obtaining an output of a laser beam at which an image patch having a specified pixel density has a specified potential based on the potential detection information from the potential detecting means; Means for adjusting the offset value with respect to the output of the beam, and forming an image under an arbitrary density condition with the laser output value obtained by adjusting the offset value.

Here, the offset used in the present invention is defined as follows. In the case where correction values for various factor changes are obtained by the detecting means in each of the plurality of driving states of the device, when changing from one driving state to another driving state, the correction values are obtained in advance by the detecting means. By inputting the difference between the correction values as the offset value to the correction value of the one driving state, accurate correction conversion to another desired driving state can be easily performed. The conversion action is called an offset, and the difference between the correction values is called an offset value.

The resolution is represented by the number of identifiable dots lined up per 25.4 mm in length, and this number is defined as dpi.

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the image forming apparatus according to the present invention will be described first with reference to the schematic diagram shown in FIG.

The image forming apparatus shown in FIG. 1 is a digital image forming apparatus and comprises an image reading section A, an image processing section B, an image forming section C, and a transfer paper transport section D as transfer paper transport means. Have been.

An automatic document feeder for automatically feeding a document is provided above the image reading section A.
The original placed on the original 1 is moved by the original transport roller 12 to the original
The sheets are separated and conveyed, and the image is read at the reading position 13a. The document for which the reading of the document has been completed is discharged onto the document discharge tray 14 by the document conveying roller 12.

On the other hand, the image of the original when placed on the platen glass 13 is read out at a speed v of a first mirror unit 15 comprising an illumination lamp and a first mirror constituting a scanning optical system, and a V-shaped image is formed. Reading is performed by moving the second mirror unit 16 including the second mirror and the third mirror located at the speed v / 2 in the same direction.

The read image is formed on a light receiving surface of an image sensor CCD as a line sensor through a projection lens 17. The line-shaped optical image formed on the image sensor CCD is sequentially photoelectrically converted into an electric signal (brightness signal), and then A
After performing / D conversion and performing processing such as density conversion and filter processing in the image processing unit B, the image data is temporarily stored in the memory.

In the image forming section C, a drum-shaped photosensitive member 21 as an image forming unit, and a charger 22 as a charging unit, a potential detecting unit 85, a developing unit 23 as a developing unit, and a transfer unit around the photosensitive member 21 are provided. A transfer unit 24, a separator 25 as a separating unit, a cleaning unit 26, a density detecting unit 80
And a PCL (precharge lamp) 27 are arranged in the order of operation. The photoreceptor 21 is formed by applying a photoconductive compound on a drum substrate, and is formed of, for example, an organic photoreceptor (O
PC) is driven and rotated clockwise as shown.

After the rotating photoconductor 21 is uniformly charged by the charger 22, image exposure based on the recorded image signal called from the memory of the image processing unit B is performed by the exposure optical system 30. Done by the beam. An exposure optical system 30 serving as a writing unit is a laser diode (LD).
36A is a light emitting light source, and the rotating polygon mirror 31,
The optical path is bent by the reflection mirror 32 via the fθ lens 34 and the cylindrical lens 35 to perform main scanning. Image exposure is performed on the photoconductor 21 at the position Ao, and rotation of the photoconductor 21 (sub-scanning) Forms a latent image.

The latent image on the photosensitive member 21 is reversely developed by the developing device 23, and a visible toner image is formed on the surface of the photosensitive member 21. In the transfer paper transport section D, paper feed units 41 (A), 41 (B), and 4 as transfer paper storage means in which transfer papers P of different sizes are stored below the image forming unit.
1C is provided, and a manual paper feed unit 42 for performing manual paper feed is provided on the side, and the transfer paper P selected from any of them is guided along the transport path 40 by the guide roller 43. The transfer paper P is temporarily stopped by a pair of registration rollers 44 that corrects the inclination and the deviation of the transfer paper that is fed and fed.
The toner image on the photoreceptor 21 is transferred to the transfer sheet P by the transfer unit 24 at the transfer position Bo, guided by the pre-transfer roller 43a and the transfer entry guide plate 46, and then discharged by the separator 25, and the transfer sheet P is exposed to light. The sheet is separated from the surface of the body 21 and transported to the fixing device 50 by the transport device 45.

The fixing device 50 has a fixing roller 51 and a pressure roller 52. By passing the transfer paper P between the fixing roller 51 and the pressure roller 52, the transfer paper P is heated and pressed to remove toner. Weld. The transfer paper P on which the toner image has been fixed is discharged onto the discharge tray 64.

As shown in the front view around the photosensitive member in FIG. 2 and the top view around the photosensitive member in FIG.
A cleaning roller 26B and a cleaning blade 26A using conductive polyurethane as No. 6 are provided, and a density detecting means 80 or a potential detecting means 85 for detecting an average density of each image patch whose density is changed for a specific resolution is provided. Is provided.

The means for adjusting the output of the laser beam of the laser exposure system for obtaining an appropriate density corresponding to each resolution, which is a major feature of the present invention, will be specifically described below.

According to the present invention, the output of the laser beam is adjusted for each resolution so that the density is in the middle of the density-sensitivity diagram of FIG. 5 in a pattern as shown in FIG. 6 or FIG. By creating an image patch of a specified pixel density of a halftone for each resolution on the photoconductor, and obtaining the output of a laser beam whose development density or potential becomes the specified density or specified potential, the sensitivity change of the photoconductor and toner An image of an appropriate density which is not affected by changes in physical properties is always obtained.

This will be described more specifically as follows. [In the case where adjustment is individually performed at 400 dpi / 600 dpi] (1) At 400 dpi, the output of the laser beam is changed so that a plurality of (at least 2) image patches having the specified pixel density of the halftone as shown in the schematic diagram of FIG. ) Is formed on the photoconductor 21. Then, as shown in the block diagram showing the configuration of the process in FIG. 8, the image patch stored on the image
The image is written on the photoreceptor 21 by an image patch creating unit 90 including a PU 92, a laser beam output adjusting unit 36, and a writing unit (exposure optical system) 30, and is developed by a developing unit 23 as a developing unit. The density is detected by the density detecting means 80.

(2) Laser beam output adjusting means 36
Of the output may be at a fixed output interval within the range of the output variable width of the laser beam, or may be a value before or after the output value (initial value) currently used. Therefore, about five image patches are also formed on the photoconductor as shown by the five lines of arrows in FIG. 8 in the range of the output width of the laser beam or around the output value of the currently used laser beam. The size of one image patch is 20 mm × 30 m as shown in the schematic diagram of FIG.
m.

(3) The image patch is a one-bit halftone dot image, and this halftone image is created by an appropriate method such as an error diffusion method or a screen method. This is stored in advance in the image processing section B in the CPU 92 as shown in the process of FIG. 8, and is taken out when necessary and input to the laser beam output adjusting means 36 for use.

(4) The image patch to be created may not necessarily be an isolated point, but is a patch having a small density of dots and a constant density. The density of the image patch is preferably 0.5, and it is desirable to include a density detecting means 80 capable of detecting the density with high sensitivity.

(5) The density detecting means 80 may detect the average density instead of detecting the density of each dot, and a sensor using diffused light may be used.

(6) As shown in the front view of FIG. 2, the top view of FIG. 3, and the block diagram showing the structure of the process of FIG. 8, the density of each image patch created on the photoreceptor is determined by the density detecting means 80. The relationship between the laser beam output (spot diameter) and the image density is automatically determined to be an appropriate density when using a 400 dpi image patch shown in the graph of FIG. 4 showing the relationship between the laser beam output and the appropriate density. To choose. In this way, it is possible to determine the output of the laser beam that can obtain the necessary appropriate density.

(7) The determined laser power is 400d
The data is stored in the non-volatile memory 93 for pi.

(8) Next, at 600 dpi using an image patch having a specified pixel density as shown in the schematic diagram of FIG.
Similarly, (1) to (7) are performed, and the determined output of the laser beam is stored in the non-volatile memory 93 for 600 dpi.

(9) When one of 400 dpi / 600 dpi is selected, an output value is selected from the non-volatile memory of the selected resolution, and an image patch is formed on the photosensitive member. Then, an image patch is automatically created for every fixed number of copies or every certain time, and the output value of the LD is determined. As a result, the image density is more accurately maintained.

(10) After an image patch is formed on the photoreceptor by changing the output of the laser beam, without developing, the latent image is shown in a front view in FIG. 2, a top view in FIG. 3, and FIG.
The electrostatic potential of the image patch of the selected resolution is read by the potential detecting means 85 as shown in the two-dot chain line in the block diagram showing the process, and the output of the laser beam is controlled so that it becomes a specified potential. You may do it. [Case where 600 dpi is also used for correction at 400 dpi only] The following (1) to (7) are the same as those in the previous section, so only the outline thereof will be described.

(1) By changing the laser power at 400 dpi, a plurality (at least one) of image patches having a specified pixel density as shown in FIG.

(2) The power may be distributed at regular intervals within the range of the laser power variable width, or at a value before or after the power currently being used (initial value). Therefore, about five image patches are created in the range of the laser power variable width or around the power of the currently used value. The size of the creation is 2
It may be about 0 mm × 30 mm.

(3) A halftone dot image of one bit is formed on the photosensitive member. The halftone image is created by an appropriate method such as an error diffusion method and a screen method.

(4) The image patch to be created does not necessarily have to be an isolated point, but is an image patch having a small density of dots and a constant density. Image patch density is 0.5
It is desirable to provide a density detecting means 80 capable of detecting the density with high sensitivity.

(5) The density detecting means 80 may detect the average density, not the density of each dot, and may use a sensor using diffused light.

(6) As shown in the front view of FIG. 2, the top view of FIG. 3, and the block diagram showing the process of FIG. 8, the density of the image patch created on the photoreceptor is determined by the density detecting means 80.
FIG. 4 shows the relationship between laser power and image density.
And a density that is an appropriate density when the image patch of 400 dpi shown in the graph is used. In this way, the laser power for obtaining the necessary appropriate density can be determined.

(7) Determined laser power is 400d
It is stored in the pi nonvolatile memory 93.

(8) When 600 dpi is selected, a value is selected from the non-volatile memory 93 for 400 dpi as shown in the process configuration of FIG. 8, and a predetermined offset value is adjusted.

(9) As shown by the dotted line in FIG. 8, the resolution conversion means 94 by inputting the offset value adjusts the offset value to output a laser beam of 600 dpi, and sends the information to the laser beam output adjustment means 36. Used for routine image creation.

(10) Apart from the above, the output of the laser beam of 400 dpi is changed and the image patch is
8, the electrostatic potential of the image patch is read by a potential detecting means 85 in the state of a latent image as shown in FIG. May be controlled, and then the offset value may be adjusted to obtain a laser beam output of 600 dpi.

As the application means, the following (11) and (1)
Special usages such as those described in 2) and (13) can also be used.

(11) An offset value selected by the user or a serviceman reflecting the user's intention is input to adjust the image density.

(12) The means for selecting the offset value may be a ten-key input, a density button selection, a DipSW selection, or the like.

(13) The output of the laser beam with the adjusted offset value is used to create an image under any desired density condition.

As can be seen from the embodiment of the present invention constructed as described above, a plurality of image patches having a desired resolution are formed on the photosensitive member by changing the output of the laser beam.
The output of the laser beam corresponding to the appropriate density is automatically selected and fixed to the output of this laser beam, and thereafter, the proper image density is maintained by maintaining the dot diameter of the laser beam determined by the state, Since the periodic density test and the re-fixation of the output of the laser beam can be easily performed, the image density is hardly affected by the deterioration of the sensitivity of the photoreceptor, the dirt in the optical path of the laser optical system, and the change of the toner properties over time. Regardless, good high image quality can be maintained. In addition, the dot diameter can be accurately and easily determined by measuring and selecting the average density of image patches of a specified density formed on the photosensitive member. Further, instead of selecting the density of the image patch on the photoconductor, the electrostatic potential may be measured in an undeveloped state and an appropriate electrostatic potential may be selected to determine the output of the laser beam. Further, by inputting the offset value, it is possible to easily and accurately switch to an image having a different resolution. Further, it becomes possible to easily obtain a special-density image quality by the operation. These effects are summarized as follows.

[0065]

According to the present invention, (1) the laser beam output of the LD
The dirt correction of the laser writing system is possible, and an image of an appropriate density can always be formed with dots of a fixed size. (2) With the laser beam output of the LD, the dot diameter of the laser beam can be corrected in accordance with the change in the development characteristics, and an image of dots of a constant size can always be formed in accordance with an appropriate image density. (3) Since the dot size can be kept constant, the toner consumption can be kept at a constant rate. (4) Since the dot diameter is individually corrected at 400 dpi / 600 dpi, a stable dot diameter can be maintained for each. (5) If the laser beam output is determined based on the correction value of 400 dpi, and the correction value is added as an offset value to 600 dpi, an image patch for dot diameter correction is created a plurality of times, and the It is possible to prevent the consumption amount and the amount of recycled toner from increasing, and to shorten the time required for correction. (6) By adding an offset value according to the user's request, it is possible to obtain the image quality of the desired arbitrary density condition as follows. That is, 1) When the offset value is set to the plus side (the output of the laser beam is increased), a thick character image is obtained. Further, an image having a high density can be obtained.

2) When the offset value is set to the minus side (the output of the laser beam is reduced), a thin character image is obtained, and the toner consumption is suppressed.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram illustrating an overall configuration of an image forming apparatus of the present invention.

FIG. 2 is a front view illustrating a configuration around a photoconductor in the image forming apparatus of the present invention.

FIG. 3 is a top view illustrating an arrangement of a density detecting unit and a potential detecting unit around a photoreceptor in the image forming apparatus of the present invention.

FIG. 4 is a graph showing a relationship between a laser beam output and an appropriate image density in a halftone.

FIG. 5 is a graph illustrating a relationship between a sensor sensitivity and an image density of the image forming apparatus.

FIG. 6 is a schematic diagram illustrating an image patch having a specified pixel density of a halftone at a resolution of 400 dpi.

FIG. 7 is a schematic diagram showing an image patch having a specified pixel density of halftone at a resolution of 600 dpi.

FIG. 8 is a block diagram illustrating a process of adjusting a laser beam output based on density detection or electrostatic potential detection of an image patch on a photoconductor to obtain a proper image.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 21 Photoreceptor 22 Charger 23 Developing device 24 Transfer device 25 Separator 26 Cleaning means 26A Cleaning blade 27 Static elimination lamp (PCL) 30 Writing means (exposure optical system) 36 Laser beam output adjusting means 36A Laser diode 80 Concentration detecting means (Density control sensor) 85 Potential detecting means 90 Image patch creating means 92 CPU 93 Non-volatile memory 94 Resolution converting means by inputting an offset value

Continued on the front page F-term (reference) 2C362 AA54 AA63 AA65 CB05 CB73 2H027 DA02 DA09 DB01 DE02 DE05 EA02 EC04 2H076 AB02 DA01 DA06 DA07 DA21 5C074 AA05 AA07 BB03 BB17 BB26 CC26 DD04 DD05 DD08 DD14 DD24 EE11H02

Claims (12)

[Claims] 1. An image forming method for forming an electrostatic latent image corresponding to image information at a plurality of resolutions on a photoreceptor by a laser beam, and developing the electrostatic latent image to obtain a visible image. Changing the output of the laser beam to form an image patch having a specified pixel density on the photoreceptor, developing the image patch, detecting the density of the developed image patch, and detecting the detected density. An image forming method comprising: obtaining an output of a laser beam at which an image patch having a specified pixel density has a specified density based on information; and forming an image for each resolution with the obtained output of the laser beam. 2. An image forming method for forming an electrostatic latent image corresponding to image information at a plurality of resolutions on a photosensitive member by a laser beam and developing the electrostatic latent image to obtain a visible image. Changing the output of the laser beam to form an image patch having a specified pixel density on the photoreceptor, developing the image patch, detecting the density of the developed image patch, and detecting the detected density. Based on the information, the output of the laser beam at which the image patch of the specified pixel density has the specified density is obtained, an image is formed with the obtained output of the laser beam, and the laser beam of another resolution is obtained. An image forming method, wherein an offset value is added to or subtracted from a laser beam output, and an image of another resolution is formed by a laser output value obtained by adding or subtracting the offset value. 3. An image forming method for forming an electrostatic latent image corresponding to image information at a plurality of resolutions on a photoreceptor by a laser beam and developing the electrostatic latent image to obtain a visible image. By respectively changing the output of the laser beam, creating an image patch of a specified pixel density on the photoconductor, detecting the potential of the image patch on the photoconductor, based on the detected potential detection information, An image forming method comprising: obtaining an output of a laser beam so that an image patch having a specified pixel density has a specified potential; and forming an image for each resolution with the obtained output of the laser beam. 4. An image forming method for forming an electrostatic latent image corresponding to image information at a plurality of resolutions on a photoreceptor with a laser beam and developing the electrostatic latent image to obtain a visible image. In, changing the output of the laser beam, create an image patch of a specified pixel density on the photoconductor, detect the potential of the image patch on the photoconductor, based on the detected potential detection information, The output of the laser beam is obtained so that the image patch of the specified pixel density has the specified potential, an image is formed with the obtained output of the laser beam, and for the laser beam of another resolution, the obtained laser beam output is used. An image forming method, wherein an offset value is adjusted, and an image of another resolution is formed with a laser output value adjusted to the offset value. 5. An image forming apparatus which forms an electrostatic latent image corresponding to image information at a plurality of resolutions on a photoreceptor with a laser beam and develops the electrostatic latent image to obtain a visible image. Changing the output of the laser beam to form an image patch having a specified pixel density on the photoreceptor, developing means for developing the image patch, and density of the developed image patch. Density detecting means for detecting, and output adjusting means for obtaining an output of a laser beam at which an image patch of a specified pixel density has a specified density based on the density detection information from the density detecting means; An image forming apparatus which forms an image for each resolution with the output of the image forming apparatus. 6. An image forming apparatus which forms an electrostatic latent image corresponding to image information with a plurality of resolutions on a photosensitive member by a laser beam and develops the electrostatic latent image to obtain a visible image. An image patch creating means for creating an image patch having a specified pixel density on the photoreceptor by changing the output of the laser beam, a developing means for developing the image patch, and detecting the density of the developed image patch Density detecting means, output adjusting means for obtaining an output of a laser beam at which an image patch having a specified pixel density has a specified density based on density detection information from the density detecting means, and an image formed by the output of the obtained laser beam. To form a laser beam of another resolution.
Resolution conversion means for adjusting the offset value with respect to the laser beam output obtained, and forming an image of another resolution with the laser output value adjusted for the offset value. Image forming apparatus. 7. An image forming apparatus which forms an electrostatic latent image corresponding to image information at a plurality of resolutions on a photosensitive member by a laser beam and develops the electrostatic latent image to obtain a visible image, Image patch creating means for creating an image patch of a specified pixel density on the photoreceptor by varying the output of the laser beam, potential detecting means for detecting the potential of the image patch, Output adjustment means for obtaining an output of a laser beam at which an image patch having a specified pixel density has a specified potential based on the potential detection information, and forming an image for each resolution with the obtained output of the laser beam. An image forming apparatus comprising: 8. An image forming apparatus for forming an electrostatic latent image corresponding to image information with a plurality of resolutions on a photosensitive member by a laser beam, and developing the electrostatic latent image to obtain a visible image. An image patch creating means for creating an image patch having a specified pixel density on the photoreceptor by changing the output of the laser beam; a potential detecting means for detecting a potential of the image patch; Based on the potential detection information, an output adjusting means for obtaining an output of a laser beam at which an image patch of a specified pixel density has a specified potential, and forming an image with the obtained output of the laser beam, for a laser beam of another resolution Resolution conversion means for adjusting the offset value with respect to the obtained laser beam output, and forming an image of another resolution with the laser output value adjusted for the offset value. An image forming apparatus comprising: 9. An image forming method for forming an electrostatic latent image corresponding to image information with a plurality of resolutions on a photosensitive member by a laser beam and developing the electrostatic latent image to obtain a visible image, wherein the laser beam By changing the output of, to create an image patch of a specified pixel density on the photoreceptor, develop the image patch, detect the density of the developed image patch, based on the detected density detection information, The output of the laser beam at which the image patch of the specified pixel density becomes the specified density is obtained, the offset value is adjusted with respect to the obtained output of the laser beam, and the image of an arbitrary density condition is obtained with the laser output value obtained by adjusting the offset value. Forming an image. 10. An image forming method for forming an electrostatic latent image corresponding to image information at a plurality of resolutions on a photosensitive member by a laser beam, and developing the electrostatic latent image to obtain a visible image,
By changing the output of the laser beam, an image patch of a specified pixel density is created on the photoreceptor, the potential of the image patch on the photoreceptor is detected, and the specified pixel is detected based on the detected potential detection information. The output of the laser beam is determined so that the density of the image patch becomes a specified potential, an offset value is adjusted with respect to the determined output of the laser beam, and an image of an arbitrary density condition is formed with the laser output value obtained by adjusting the offset value. An image forming method characterized by forming. 11. An image forming apparatus for forming an electrostatic latent image corresponding to image information at a plurality of resolutions on a photosensitive member by a laser beam and developing the electrostatic latent image to obtain a visible image,
Changing the output of the laser beam to form an image patch having a specified pixel density on the photoreceptor; developing means for developing the image patch; and detecting the density of the developed image patch. Density detection means, output adjustment means for obtaining an output of a laser beam at which an image patch having a specified pixel density has a specified density based on density detection information from the density detection means, and offset with respect to the obtained output of the laser beam. An image forming apparatus comprising: means for adjusting a value; and forming an image under an arbitrary density condition using a laser output value adjusted by the offset value. 12. An image forming apparatus for forming an electrostatic latent image corresponding to image information at a plurality of resolutions on a photosensitive member by a laser beam and developing the electrostatic latent image to obtain a visible image,
By changing the output of the laser beam, image patch creating means for creating an image patch of a specified pixel density on the photoreceptor, potential detecting means for detecting the potential of the image patch,
Output adjusting means for obtaining an output of a laser beam at which an image patch having a specified pixel density has a specified potential based on the potential detection information from the potential detecting means; and means for adjusting an offset value with respect to the obtained output of the laser beam. An image forming apparatus that forms an image under an arbitrary density condition with a laser output value adjusted by adding or subtracting the offset value.