JP2007237400A - Image forming apparatus and method for forming image by suppressing reciprocity law failure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve image quality by a method wherein an amount of toner as a developer to be developed on a photosensitive body is sequentially derived in accordance with image data and power of an optical beam is modulated by each pixel based on the derived result and an actual amount of the toner including prestored reciprocity law failure or influence of variation of a photosensitive body. <P>SOLUTION: This image forming apparatus is configured to perform optical scanning and comprises a deriving means for deriving a correction coefficient by using image data on the N-th order which is the last in the m-th main scanning, a storage means for storing main scanning image data on the first order in the (m+1)-th main scanning which is the next to image data on the N-th order in the m-th main scanning, and an adjustment means for adjusting a light quantity of the first light flux of a main scanning exposure on the (m+1)-th order or later by using the correction coefficient derived by the deriving means. The letter "m" represents an integer equal to or greater than 1. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention reduces the occurrence of reciprocity law failure and an image forming apparatus that performs scanning exposure using a plurality of light beams modulated by a rotating polygon mirror, develops a developer on an electrostatic latent image formed on a recording medium, and forms an image. The present invention relates to an image forming method.

  Conventionally, in image formation by an electrophotographic method, in the simultaneous main scanning exposure method using a plurality of light sources, density variation characteristics due to so-called “reciprocity failure” have occurred, and image quality has been a problem. If the exposure amount follows the reciprocity law in which the logarithmic relationship between the exposure time and the aperture is a theoretical value, the obtained image becomes a good image. However, the above-described reciprocity failure is a phenomenon that shifts from such proper exposure, and generally occurs when the exposure time is extremely short or when the exposure time is long.

  When this phenomenon occurs, it can be said that the irradiation light quantity and the toner quantity are not proportional. For example, when two beam spots adjacent in the sub-scanning direction are simultaneously formed on the surface of the photoconductor, and when the two beam spots are formed on the surface of the photoconductor with a time difference, these surfaces The potential will be different. Therefore, when a latent image formed on such a photoreceptor is developed using toner, an image having density variation characteristics due to the above-described reciprocity law failure is formed.

  In the electrophotographic system in which the photosensitive member is simultaneously scanned and exposed with a plurality of light sources as shown in FIG. 1, the scanning exposure start timings of adjacent LD0 to LD3 are the same as shown in FIG. The interval from the scanning exposure start timing by the LD3 to the start of the scanning exposure of the LD0 of the (m + 1) th scanning is long after T time. In other words, a deviation occurs due to exposure timing having a different scanning cycle, and this different exposure timing causes density unevenness due to a so-called reciprocity failure, resulting in a problem of image quality.

  As conventional techniques for solving such problems, the inventions disclosed in Patent Documents 1 and 2 are known. For example, Patent Document 1 discloses that in a scanning exposure method using a plurality of light beams, m light beams are arranged in a line so that one portion of adjacent light beams overlaps on the photosensitive surface, and the arrangement direction of the light beams Image data representing exposure or non-exposure for each of the m light beams when performing two-dimensional scanning exposure by performing main scanning that scans in the intersecting direction and sub-scanning that scans in the arrangement direction of the light beams. And N is an integer equal to or greater than 1, and exposure of the m-th light beam in the light beam performing the N-th main scan and exposure of the first light beam in the light beam performing the N + 1-th main scan. , The power of at least one of the first light beam and the m-th light beam is changed, and the m-th light beam in the light beam for N-th main scanning is changed. Light beam and A plurality of light beams that maintain the power of the light beam corresponding to the exposure when one of the first light beams in the light beam that performs the + 1st main scanning is exposed and the other is not exposed. An invention of a scanning exposure method using a light beam is described.

Further, in Patent Document 2, a laser beam emitted from each light source of a laser diode array in which a plurality of light sources are arranged on one chip is periodically changed by a rotary polygon mirror in the sub-scanning direction. In an electrophotographic apparatus that irradiates a rotating photoconductor in the main scanning direction with a positional difference in the sub-scanning direction and forms an electrostatic latent image on the surface of the photoconductor, the number of the light emitting sources is set to n (n ≧ 2) When the interval in the sub-scanning direction of the laser beam from each of the light emitting sources adjacent on the photoconductor is d, and the amount the photoconductor advances in the time of one scan by the rotary polygon mirror is L, L = An invention of an electrophotographic apparatus characterized by having a relationship of nd / k (k is a natural number of 2 or more which is relatively prime with the number n of light emitting sources) is described.
Japanese Patent No. 2685346 JP 2004-20911 A

  However, in recent high density and high image quality, it is not possible to obtain an image quality that can ignore the influence of density unevenness by simply determining the presence or absence of image data and uniformly modulating the power of the light beam. .

  In view of such a problem, the present invention stores deriving means for deriving a correction coefficient from the Nth image data in the m-th main scan, and the first image data in the N-th next m + 1-th main scan. It is an object of the present invention to provide an image forming apparatus that adjusts the amount of light in the (m + 1) th and subsequent main scanning exposures using a correction coefficient, and an image forming method that reduces reciprocity failure.

  In order to solve the above problem, the invention according to claim 1 is directed to a light source that emits a plurality of light beams, a rotating polygon mirror that polarizes each light beam emitted from the light source, and each polarized light beam. A recording medium for forming an electrostatic latent image by main scanning exposure, and an image forming apparatus in which the electrostatic latent image is developed with a developer to form an image, which is the final in the m-th main scanning. Deriving means for deriving a correction coefficient using the Nth image data, and storing means for storing the first main scanning image data in the Nth next m + 1th main scanning in the mth main scanning. An image forming apparatus (where m is 1 or more), and a first adjusting unit that adjusts the amount of light of the first light beam in the m + 1 and subsequent main scanning exposures using the correction coefficient derived by the deriving unit. Represents an integer of .

  According to a second aspect of the present invention, a light source that emits a plurality of N light beams, a rotary polygon mirror that polarizes each light beam emitted from the light source, and main scanning exposure using each of the polarized light beams is electrostatically performed. A recording medium on which a latent image is formed and an image forming apparatus in which the electrostatic latent image is developed with a developer to form an image, the image corresponding to main scanning exposure with the N plurality of light beams on a one-to-one basis Among the data, the correction coefficient derived using the first main scan image data in the m + 1th main scan and the Nth image data in the mth main scan uses the correction coefficient derived in the m + 1th and subsequent main scan exposures. An image forming apparatus having a second adjusting means for adjusting a light amount of the first light beam and a light amount of the Nth light beam in the m-th and subsequent main scanning exposures (where m represents an integer of 1 or more); It is characterized by.

  According to a third aspect of the present invention, in the image forming apparatus according to the first or second aspect, the light amount adjustment by the adjusting unit is adjusted by changing a density level of the image data.

  According to a fourth aspect of the present invention, in the image forming apparatus according to the first or second aspect, the light amount adjustment by the adjusting unit is performed by adjusting the light amount adjustment of the light source by modulating a pulse width with a laser control signal. And

  According to a fifth aspect of the present invention, in the image forming apparatus according to the first or second aspect, the light amount adjustment by the adjusting unit is performed by adjusting the light amount adjustment by bias control of a laser control signal.

  According to a sixth aspect of the present invention, there is provided a static light source that emits at least N light beams, a rotary polygon mirror that polarizes a light beam emitted from the light source, and main scanning exposure using the polarized light beam. An image corresponding one-to-one to main scanning exposure with the N plurality of light beams using a recording medium for forming a latent image and an image forming apparatus in which the electrostatic latent image is developed with a developer to form an image. Among the data, the correction coefficient derived using the first main scan image data in the m + 1th main scan and the Nth image data in the mth main scan in the m + 1th and subsequent main scan exposures. An image forming method for reducing reciprocity failure including a light amount adjustment step of adjusting a light amount of a first light beam and a light amount of an Nth light beam in m-th and subsequent main scanning exposures (where m is an integer of 1 or more) Represents Characterized in that there.

  According to a seventh aspect of the present invention, in the image forming method in which the reciprocity law failure is reduced according to the sixth aspect of the invention, the light amount adjusting step is adjusted by changing a density level of the image data, or a light source The light quantity adjustment is adjusted by modulation of a pulse width by a laser control signal or by bias control of a laser control signal.

  As described above, according to the image forming apparatus and the image forming method with reduced reciprocity failure, the derivation means for deriving the correction coefficient from the Nth image data in the m-th main scan, the Nth next The amount of light in the m + 1th and subsequent main scanning exposures can be adjusted using the storage means for storing the first image data in the (m + 1) th main scanning and the correction coefficient.

  In the present embodiment, for example, the amount of toner to be developed on the photoreceptor is sequentially derived according to the image data, and the derivation result and actual effects including the influence of reciprocity law failure and photoreceptor variation stored in advance are included. The purpose is to further improve the image quality by modulating the power of the light beam for each pixel from the amount of toner.

  The image forming apparatus according to the present embodiment and the image forming method with reduced reciprocity law failure are electrophotographic image forming apparatuses, and can be applied to an image forming apparatus based on a simultaneous main scanning exposure method using a plurality of light sources. It becomes possible to improve the image quality problem caused by the influence of the reciprocity failure which has been a problem and the density unevenness caused by the characteristic variation of the recording medium and the developer.

  Hereinafter, the image forming apparatus of the present embodiment will be described in detail with reference to the drawings. In addition, this embodiment is not limited to what is described below, A various change is possible in the range which does not deviate from the meaning.

  The image forming apparatus according to the present embodiment includes a derivation unit that derives a correction coefficient using the Nth image data that is the last in the m-th main scan, and the Nth next m + 1 in the m-th main scan. Adjustment for adjusting the light quantity of the first light flux of the m + 1th and subsequent main scanning exposures using the storage means for storing the first main scanning image data in the main scanning for the first time and the correction coefficient derived by the deriving means. Means.

  Further, the image forming apparatus according to the present embodiment includes the first main scanning image data in the (m + 1) th main scanning among the image data corresponding to the one-to-one main scanning exposure with N multiple light beams, and the mth time. Based on the correction coefficient derived using the Nth image data in the main scanning, the light amount of the first light beam in the m + 1th and subsequent main scanning exposures, and the light amount of the Nth light beam in the mth and subsequent main scanning exposures It is characterized by adjusting.

  As an image forming apparatus of this embodiment and an image forming method with reduced reciprocity failure, as shown in the configuration example of the optical writing unit shown in FIG. 1, an LDA having a plurality of light sources, for example, four laser light sources. An image forming apparatus using one (laser diode array (number of light beams 4)) 101 will be described as an example.

FIG. 3 is a diagram schematically showing the configuration of the optical writing unit of the image forming apparatus having the optical writing unit shown in FIG.
As shown in FIG. 3, the optical writing unit according to the image forming apparatus of the present embodiment uses an image data input unit (not shown) to read an image existing on the paper surface and use image information divided for each color. Based on certain image data LDD0 to LDD3, the light beams from the laser light sources LD0 to LD3 in the LDA 101 are irradiated to the uniformly charged photoconductor to form a latent image. As shown in FIG. 3, for example, among the image data LDD0 to LDD3, LDD3 is stored in a storage medium (RAM) 1 for one main scan. Then, as shown in FIG. 4A, the LD3 scan line p and LD0 scan are performed as shown in FIG. 4B by using the (m + 1) th scan LDD0 data corresponding to the next line of the LDD3 which is m-th main scanned. A toner amount to be developed (hereinafter referred to as a polymerization (superposition) line toner amount) of an exposure line r (hereinafter referred to as a polymerization (superposition) line r) between the line q is predicted.

The amount of toner in the polymerization line developed in the polymerization line r can be determined as shown in FIG. 4, for example.
As shown in FIG. 4A, the m-th main scan q line follows the m-th main scan scan line p. As shown in FIG. 4B, the polymerization line toner amount D _est developed at the target pixel “D” of the polymerization line r is the image data j1 to j3 exposed by the main scan of LD3 and the main scan of LD0. It can be expressed by the following formula (1) obtained by multiplying the image data k1 to k3 to be exposed and the coefficients 1 to 6 and subtracting the threshold 1 which is the exposure sensitivity threshold of the photoreceptor from the obtained value.

D _est = (coefficient 1 × j1 + coefficient 2 × j2 + coefficient 3 × j3) + (coefficient 4 × k1 + coefficient 5 × k2 + coefficient 6 × k3) −threshold 1 (1)

  In the example of the above formula (1), the characteristic variation of the photoconductor, the toner, and the LDA is absorbed by reflecting each coefficient and the threshold value 1, in other words, the characteristic variation of the LDA is included in each coefficient and the threshold value 1. It is possible to express. The toner amount derivation method for the polymerization line shown here is an example, and the present embodiment is not limited to this formula.

Next, as shown in FIG. 3 and Tables 1 to 5, the polymerization line toner amount in the case of the influence of reciprocity failure is derived in advance from the measured value, and D _real is stored in a storage medium such as NVRAM (Non Volatile RAM). The polymerization line toner actual measurement unit is stored.

As shown in FIG. 3, the correction coefficient deriving unit obtains data from 3ch image data LDD3, which is one of image data of a plurality of channels, for example, 4ch (the number of light beams is the same as the number of laser light sources constituting the array). A RAM 1 to be stored, and a polymerization line toner amount calculation unit 2 that calculates the toner amount of the polymerization line from the image data from the 0ch image data LDD0 and the data value from the RAM 1. Further, this polymerization is provided. The line toner amount calculation unit 2 sequentially compares D _real stored in the RAM 1 with the polymerization line toner amount calculation value D _est , where the actually measured polymerization line toner amount D _real is shown in Table 1. Table 2 shows the predicted polymerization line toner amount _Dest .

The comparison result between D _real and D _est is sent to the correction coefficient deriving unit 3, and the correction coefficient deriving unit 3 derives the light amount correction coefficient of LD0. The comparison results are shown in Table 3.

  Examples of correction coefficients derived by the correction coefficient deriving unit 3 are shown in Tables 4 and 5.

  In this embodiment, it is possible to apply such a configuration in which such a correction coefficient is derived by an LUT (Look Up Table) or a configuration in which a correction coefficient is derived for each pixel.

  The derived correction coefficient is used and calculated by the light amount adjusting means of the LD0. This makes it possible to adjust the light amount of LD0 including the influence of errors due to variations in the characteristics of the photoconductor, and further improve the image quality.

For example, in the present embodiment, as illustrated in FIG. 3, the toner of the superposition line is obtained from the RAM 1 that stores data from the 3ch image data LDD3, the image data from the 0ch image data LDD0, and the data value from the RAM. The polymerization line toner amount calculation unit 2 that calculates the amount, and the polymerization line toner amount calculation unit 2 sequentially compares D _real stored in the RAM 1 with the polymerization line toner amount calculation value D _est and derives a correction coefficient. The correction coefficient deriving unit 3 derives the light amount correction coefficient of the LD0 that is sent to the unit 3.

  Further, in the present embodiment, as shown in FIG. 5, in addition to the configuration shown in FIG. 3, image data from the 0ch image data LDD0 and the correction coefficient for adjusting the light amount of LD0 derived by the correction coefficient deriving unit 3 are used. Further, a density modulation circuit 5 for increasing or decreasing the density level (density value) of the image data LDD0 is further added. The density modulation circuit 5 increases or decreases the density level (density value) of the image data LDD0, and the modulated image data (a signal obtained by digitizing the image data) is input to the LD driver circuit that drives the LDA. With this configuration, the image quality can be further improved.

  Further, in the present embodiment, as shown in FIG. 6, the output from the polymerization line toner calculation unit of the input 0ch image data LDD0 signal is input to the correction coefficient derivation unit together with the actually measured polymerization line toner amount and output. That is, using the derived LD0 light quantity adjustment correction coefficient, a signal subjected to pulse width modulation by the pulse width modulation circuit 7 is transmitted. The LDA drive signal of the LD driver circuit is controlled by outputting the transmitted signal to the LD driver. The operations of the other parts are the same as those shown in FIG.

  Further, in this embodiment, as shown in FIG. 7, the bias level of the LD driver circuit for adjusting the LDA drive signal level is controlled by a bias control circuit 8 instead of the pulse width modulation circuit 7 shown in FIG. Others are the same as those of the operation example of the circuit shown in FIG. As described above, the image quality can be improved also in the present embodiment shown in the configuration examples of FIGS.

  Next, in the image forming apparatus of this embodiment and the image forming method with reduced reciprocity failure, a plurality of RAMs or the like are provided as storage means for individually storing each data of the ch image data LDD0 to LDD3. A configuration example in the case of the above will be described with reference to FIGS. In the present embodiment, an example of an image forming apparatus using one LDA (laser diode array) having four laser light sources (number of light beams 4) in the configuration of the optical writing apparatus as shown in FIG. explain.

  As shown in FIG. 8, the image data LDD0 to LDD3 corresponding to the laser light sources LD0 to LD3 in the LDA are stored in the storage medium for one main scan, and as shown in FIG. Using the m + 1-th scan LDD0 data corresponding to the line, the amount of the polymerization line toner developed on the polymerization line r between the LD3 scan line p and the LD0 scan line q is predicted. The calculation of the polymerization line toner amount developed in the polymerization line r is as shown in the above-described embodiment.

Next, as shown in FIG. 8 and Tables 1 to 5, RAM 1 ′, 1 ′,... For storing data from image data 0 to 3ch image data LDD0 to LDD3 for each channel, 0ch A polymerization line toner amount calculation unit 2 that calculates the toner amount of the polymerization line from the image data from the image data LDD0 and the data value from the RAM 1 ′ that stores the data from the image data 3ch image data LDD3, and the polymerization line toner The amount calculation unit 2 sequentially compares D _real stored in the RAM 1 ′ with the polymerization line toner amount calculation value D _est , sends the result to the correction coefficient deriving unit 3, and the correction coefficient deriving unit 3 sets the LD 0 and LD 3. A light amount correction coefficient is derived.

Also in this configuration, the amount of polymerization line toner when there is an influence of reciprocity failure is derived in advance from the measured value and stored as D _{real in} a storage medium such as NVRAM. D _real and the polymerization line toner amount calculation value D _est are sequentially compared, the light amount correction coefficient of LD0 and LD3 is derived based on the result, and the light amount correction coefficient of LD0 is stored in the storage medium for one main scanning, thereby correcting the correction coefficient. The application timing is adjusted. The correction coefficients shown in Tables 4 and 5 can be applied to a configuration using a look-up table (LUT) or a configuration in which a correction coefficient is derived for each pixel.

  The derived LD3 light quantity correction coefficient is applied to the LD3 light quantity adjustment means, the LD0 light quantity correction coefficient delayed by one main scanning period is used as the LD0 light quantity adjustment means, and the LD3 light quantity correction coefficient is used as the LD3 light quantity adjustment means. This makes it possible to adjust the light amounts of LD0 and LD3, including the influence of errors due to variations in the characteristics of the photoconductor, and to improve the image quality by toner development.

  Further, as shown in FIG. 9, the density modulation circuit increases or decreases the density levels of the image data LDD0 and LDD3 using the derived LD3 light quantity adjustment correction coefficient and the LD0 light quantity adjustment correction coefficient delayed by one main scanning period. Then, the image quality can be improved by inputting the modulated image data to the LD driver circuit for driving the LDA. The derived 0ch light quantity correction coefficient (temporarily stored in the RAM) and 3ch light quantity correction coefficient are input to the density modulation section, and each density modulation section controls the LD driver using these correction coefficients. As described above, the RAM 1 ′ is provided so as to adjust the light amount of the first light beam in the (m + 1) th and subsequent main scanning exposures and the light amount of the Nth light beam in the mth and subsequent main scanning exposures.

  Further, in the present embodiment, as shown in FIG. 10, the derived light amount adjustment correction coefficient (the input 0ch image data LDD0 signal and the 3ch image data LDD3 stored in the RAM 1 ′ are corrected for the output from the superposition line toner calculation unit. The 0ch light amount correction coefficient and the 3ch light amount correction coefficient stored in the RAM and the 0ch image data LDD0 to LDD3 temporarily stored in the RAM 1 ′, respectively. Are used to control the LDA drive signal of the LD driver circuit by outputting the pulse width modulated signal by the pulse width modulation circuit to the LD driver. The operations of the other parts are the same as in the case shown in FIG.

  Furthermore, in this embodiment, as shown in FIG. 11, the LDA drive signal of the LD driver circuit is controlled in the same manner as in FIG. 10 except that the pulse width modulation circuit shown in FIG. 10 is replaced with a bias modulation circuit. The operation is the same as that shown in FIG.

  As described above, in the image forming apparatus and the image forming method with reduced reciprocity failure, the optical writing unit uses the image data for each channel to prevent the reciprocity failure. Deriving means for deriving a correction coefficient using the Nth image data which is the last in the m-th main scan, and the N-th next m + 1-th main scan in the m-th main scan. Using the storage means (RAM1, 1 ′, etc.) for storing the first main scanning image data and the correction coefficient derived by the deriving means, the light quantity of the first light flux of the m + 1th and subsequent main scanning exposures is adjusted. Adjusting means.

  In the above LDA, the number of channels (ch) N is described as 4. However, in order to increase the number of pixels that can be formed in one scan, the number of channels can be further increased. If the number of channels N increases, the number of image data LDD0 to LDD3 (when N = 4) becomes LDD0 to LDD (N-1).

  The optical writing unit used in the image forming apparatus of the present invention can also be used as a light irradiating device that illuminates a certain image data as a key, and the image forming apparatus having such an optical writing unit has the number of luminous fluxes. Depending on the number of independent arrays, high-quality images can be formed on various recording media.

FIG. 3 is a diagram illustrating a structure example of an optical writing unit in an image forming apparatus. It is a figure which shows the example which the density | concentration nonuniformity produced by the exposure timing from which a scanning period differs, and the reciprocity failure occurred. FIG. 3 is a diagram illustrating a configuration in which image data of the image forming apparatus of the present embodiment is stored in a storage medium for one main scan. FIG. 6 is a diagram for explaining prediction of the amount of toner developed at the exposure line r between the LD3 scan line p and the LD0 scan line q using the m + 1-th scan LD0 data of the next line of the m3 main-scanned LD3. It is. 1 is a diagram illustrating a configuration example of an image forming apparatus according to an exemplary embodiment, and illustrates an optical writing unit of an image forming apparatus using a plurality of laser light sources. FIG. 3 is a diagram illustrating a configuration example of an image forming apparatus according to an exemplary embodiment, and illustrates a driving signal of an LD driver circuit controlled by a signal that has been pulse width modulated using a derived light amount adjustment correction coefficient. 1 is a diagram illustrating a configuration example of an image forming apparatus according to an exemplary embodiment, and illustrates a bias control circuit controlling a bias level of an LD driver circuit. FIG. FIG. 2 is a diagram illustrating a configuration example of an image forming apparatus according to the present embodiment, storing image data in a storage medium for one main scan, and developing the image on a superposition line r using m + 1th scan data that is mth main scanned. It is the figure which estimated the amount of superposition | polymerization line toners. FIG. 4 is a diagram illustrating a configuration example of the image forming apparatus according to the present embodiment, and using the derived light amount adjustment correction coefficient and light amount adjustment correction coefficient, the density levels of the image data LD0 and LD3 are increased and decreased, and modulated to the LD driver circuit. It is a figure explaining inputting post-image data. FIG. 2 is a diagram illustrating a configuration example of an image forming apparatus according to the present embodiment, and controls LDA by performing pulse width modulation using a derived light amount adjustment correction coefficient and a light amount adjustment correction coefficient delayed by one main scanning period. It is the figure which showed that. 1 is a diagram illustrating a configuration example of an image forming apparatus according to an exemplary embodiment, and illustrates a bias level of an LD driver circuit that adjusts an LDA drive signal level by a bias control circuit. FIG.

Explanation of symbols

1,1 ', 9 Recording medium (RAM)
2 Polymerization line toner amount calculation unit 3 Correction coefficient deriving unit 4 Polymerization line toner amount actual measurement unit 5 Density modulation circuit 6 LD (laser diode) driver 100 Polygon mirror 101 Laser diode array (LDA)
102 synchronization detection sensor 103 photoconductor

Claims (7)

A light source that emits a plurality of light beams, a rotary polygon mirror that polarizes each light beam emitted from the light source, a recording medium that forms an electrostatic latent image by main scanning exposure of each polarized light beam, and the static An image forming apparatus in which an electrostatic latent image is developed with a developer to form an image,
deriving means for deriving a correction coefficient using the Nth image data which is the last in the m-th main scan;
Storage means for storing first main-scan image data in the N-th next m + 1-th main scan in the m-th main scan;
An image forming apparatus comprising: a first adjusting unit that adjusts a light quantity of a first light beam of m + 1 and subsequent main scanning exposures using a correction coefficient derived by the deriving unit (where m Represents an integer of 1 or more). A light source that emits N light beams, a rotary polygon mirror that polarizes each light beam emitted from the light source, a recording medium that forms an electrostatic latent image by main scanning exposure using each polarized light beam, An image forming apparatus in which the electrostatic latent image is developed with a developer to form an image,
Of the image data corresponding to the main scanning exposure with the N plural light beams on a one-to-one basis, the first main scanning image data in the (m + 1) th main scanning, and the Nth image data in the mth main scanning, The second adjustment means adjusts the light quantity of the first light beam in the (m + 1) th and subsequent main scanning exposures and the light quantity of the Nth light beam in the mth and subsequent main scanning exposures using the correction coefficient derived using An image forming apparatus characterized in that m represents an integer of 1 or more.   The image forming apparatus according to claim 1, wherein the light amount adjustment by the adjustment unit is performed by changing a density level of image data.   3. The image forming apparatus according to claim 1, wherein the light amount adjustment by the adjustment unit is performed by adjusting the light amount adjustment of the light source by modulating a pulse width with a laser control signal.   The image forming apparatus according to claim 1, wherein the light amount adjustment by the adjustment unit is performed by adjusting the light amount adjustment by bias control of a laser control signal. A light source that emits at least N light beams, a rotary polygon mirror that polarizes the light beam emitted from the light source, a recording medium that forms an electrostatic latent image by performing main scanning exposure with the polarized light beam, and Using an image forming apparatus in which the electrostatic latent image is developed with a developer to form an image,
Of the image data corresponding to the main scanning exposure with the N plural light beams on a one-to-one basis, the first main scanning image data in the (m + 1) th main scanning, and the Nth image data in the mth main scanning, And a light amount adjustment step of adjusting the light amount of the first light beam in the (m + 1) th and subsequent main scanning exposures and the light amount of the Nth light beam in the mth and subsequent main scanning exposures. An image forming method with reduced characteristic reciprocity failure (where m represents an integer of 1 or more).   The light amount adjusting step is adjusted by changing the density level of the image data, the light amount adjustment of the light source is adjusted by modulating a pulse width by a laser control signal, or adjusted by bias control of the laser control signal. The image forming method according to claim 6, wherein reciprocity failure is reduced.

Images