JP2012150181A - Image forming apparatus and image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus employing an electrophotographic system that accurately draws an edge part while reducing the edge effect.SOLUTION: An image forming apparatus employing an electrophotographic system includes a print engine 11 that specifies a distribution pattern of an electrostatic latent image based on an exposure signal before correction, specifies the degree of change of an electric field of a pixel of interest based on the distribution pattern of an electrostatic latent image, corrects the exposure signal based on the degree of change of the electric field, and supplies an exposure signal after correction to an exposure device 2. The exposure device 2 irradiates a photoreceptor drum with light based on the exposure signal and forms an electrostatic latent image.

Description

  The present invention relates to an image forming apparatus and an image forming method.

  In an electrophotographic image forming apparatus, it is known that an edge effect in which toner is excessively supplied by an edge electric field occurs at an edge portion of an electrostatic latent image formed on a photoreceptor.

  An image forming apparatus that corrects such an edge effect has been proposed (see, for example, Patent Documents 1 and 2).

  The image forming apparatus described in Patent Document 1 reduces the edge effect by applying a low-pass filter to image data before binarization.

  The image forming apparatus described in Patent Document 2 optically detects a toner image on a photosensitive drum, specifies the degree of edge effect based on the density distribution based on the detection result, and filters according to the degree. Is applied to the image data before binarization to reduce the edge effect.

JP 61-242468 A Japanese Patent Laid-Open No. 06-060181

  In the above-mentioned technique, the edge effect is reduced by image processing on the image data. However, since the edge portion is processed by simply filtering the image data, the electrostatic latent image (particularly the edge portion) is accurately drawn. There is a possibility that it will not be.

  The present invention has been made in view of the above problems, and by modeling the electrostatic latent image distribution pattern and the electric field strength distribution pattern based on the distribution pattern, the edge effect can be drawn while accurately drawing the edge portion. An object of the present invention is to obtain an image forming apparatus and an image forming method capable of reducing the above.

  In order to solve the above problems, the present invention is configured as follows.

  An image forming apparatus according to the present invention includes a photoconductor, an exposure device that irradiates the photoconductor with light based on an exposure signal to form an electrostatic latent image, and a control unit that supplies the exposure signal to the exposure device. Then, the control unit specifies the distribution pattern of the electrostatic latent image based on the exposure signal before correction, specifies the electric field variation of the target pixel based on the distribution pattern of the electrostatic latent image, and based on the electric field variation The exposure signal is corrected and the corrected exposure signal is supplied to the exposure apparatus.

  Thereby, since the distribution pattern of the electrostatic latent image and the electric field intensity distribution pattern based on the distribution pattern are modeled, the edge effect can be reduced while accurately drawing the edge portion.

  In addition to the image forming apparatus described above, the image forming apparatus according to the present invention may be configured as follows. In this case, the control unit calculates the exposure signal correction amount by multiplying the electric field variation by a predetermined gain.

  The image forming apparatus according to the present invention may be configured as follows in addition to any of the image forming apparatuses described above. In this case, the control unit calculates the exposure signal correction amount by multiplying the product of the electric field variation and the value of the target pixel in the distribution pattern of the electrostatic latent image by a predetermined gain.

  This makes it possible to accurately draw a portion such as an isolated dot that is difficult to be developed with toner.

  The image forming apparatus according to the present invention may be configured as follows in addition to any of the image forming apparatuses described above. In this case, the control unit specifies a distribution pattern of the electrostatic latent image by applying a low-pass filter to the distribution pattern of the exposure signal before correction.

  The image forming apparatus according to the present invention may be configured as follows in addition to any of the image forming apparatuses described above. In this case, the low pass filter is a Gaussian filter.

  Thereby, the distribution pattern of the electrostatic latent image formed on the photosensitive member by the light from the exposure apparatus is accurately specified.

  The image forming apparatus according to the present invention may be configured as follows in addition to any of the image forming apparatuses described above. In this case, the control unit specifies the electric field fluctuation degree of the target pixel based on the electric field intensity distribution pattern by each pixel in the distribution pattern of the electrostatic latent image.

  Thereby, the electric field fluctuation degree of the target pixel is accurately specified.

  The image forming apparatus according to the present invention may be configured as follows in addition to any of the image forming apparatuses described above. In this case, the control unit performs pulse width modulation on the corrected exposure signal, and controls the amount of light applied to the photosensitive member with the corrected exposure signal subjected to pulse width modulation.

  Thus, excessive supply of toner due to the edge effect is suppressed based on the corrected exposure signal.

  The image forming apparatus according to the present invention may be configured as follows in addition to any of the image forming apparatuses described above. In this case, the control unit performs pulse amplitude modulation on the exposure signal after correction, and controls the amount of light that is applied to the photoconductor with the exposure signal after correction subjected to pulse amplitude modulation.

  Thus, excessive supply of toner due to the edge effect is suppressed based on the corrected exposure signal.

  An image forming method according to the present invention is an image forming method in an image forming apparatus including a photoconductor and an exposure device that irradiates the photoconductor with light based on an exposure signal to form an electrostatic latent image, before correction. The distribution pattern of the electrostatic latent image is specified based on the exposure signal, the electric field fluctuation degree of the target pixel is specified based on the distribution pattern of the electrostatic latent image, and the exposure signal is corrected based on the electric field fluctuation degree. Then, the corrected exposure signal is supplied to the exposure apparatus.

  Thereby, since the distribution pattern of the electrostatic latent image and the electric field intensity distribution pattern based on the distribution pattern are modeled, the edge effect can be reduced while accurately drawing the edge portion.

  According to the present invention, since the distribution pattern of the electrostatic latent image and the electric field strength distribution pattern based on the distribution pattern are modeled in the image forming apparatus, the edge effect can be reduced while accurately drawing the edge portion. Can do.

FIG. 1 is a side view showing a part of a mechanical internal configuration of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a block diagram showing a part of the electrical configuration of the image forming apparatus according to the embodiment of the present invention. FIG. 3 is a block diagram showing a configuration of the exposure signal correction unit in the first embodiment. FIG. 4 is a diagram illustrating an example of the filter coefficient of the electrostatic latent image prediction unit in FIG. FIG. 5 is a diagram illustrating an example of the filter coefficient of the electric field fluctuation prediction unit in FIG. FIG. 6 is a diagram showing an example of a distribution pattern of exposure signal values before correction. FIG. 7 is a diagram showing an example of a distribution pattern of the electrostatic latent image obtained from the exposure signal of FIG. 6 by the electrostatic latent image prediction unit in the first embodiment. FIG. 8 is a diagram showing an example of a corrected exposure signal distribution pattern obtained from the exposure signal of FIG. 6 by the exposure signal correction unit in the first embodiment. FIG. 9 is a diagram showing a simulation result of the distribution pattern of the electrostatic latent image by the exposure signal before correction shown in FIG. FIG. 10 is a diagram showing a simulation result of the distribution pattern of the electrostatic latent image by the exposure signal after the exposure signal of FIG. 6 is corrected by the exposure signal correction unit in the first embodiment. FIG. 11 is a diagram showing another example of a distribution pattern of exposure signal values before correction. FIG. 12 is a diagram showing an example of a distribution pattern of the electrostatic latent image obtained from the exposure signal of FIG. 11 by the electrostatic latent image prediction unit in the first embodiment. FIG. 13 is a diagram showing an example of a corrected exposure signal distribution pattern obtained from the exposure signal of FIG. 11 by the exposure signal correction unit in the first embodiment. FIG. 14 is a diagram showing a simulation result of the distribution pattern of the electrostatic latent image by the exposure signal before correction shown in FIG. FIG. 15 is a diagram showing a simulation result of the distribution pattern of the electrostatic latent image by the exposure signal after the exposure signal of FIG. 11 is corrected by the exposure signal correction unit in the first embodiment. FIG. 16 is a block diagram showing a configuration of the exposure signal correction unit in the second embodiment. FIG. 17 is a diagram illustrating an example of a corrected exposure signal distribution pattern obtained from the exposure signal of FIG. 6 by the exposure signal correction unit according to the second embodiment. FIG. 18 is a diagram showing a simulation result of the distribution pattern of the electrostatic latent image by the exposure signal after the exposure signal of FIG. 6 is corrected by the exposure signal correction unit in the second embodiment. FIG. 19 is a diagram showing an example of a corrected exposure signal distribution pattern obtained from the exposure signal of FIG. 11 by the exposure signal correction unit according to the second embodiment. FIG. 20 is a diagram showing a simulation result of the distribution pattern of the electrostatic latent image by the exposure signal after the exposure signal of FIG. 11 is corrected by the exposure signal correction unit in the second embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

Embodiment 1 FIG.

  FIG. 1 is a side view showing a part of a mechanical internal configuration of an image forming apparatus according to an embodiment of the present invention. This image forming apparatus is an apparatus having an electrophotographic printing function, such as a printer, a facsimile machine, a copying machine, or a multifunction machine.

  The image forming apparatus of this embodiment has a tandem color developing device. The color developing device includes photosensitive drums 1a to 1d, an exposure device 2, and developing units 3a to 3d. The photoconductor drums 1a to 1d are four-color photoconductors of cyan, magenta, yellow, and black.

  The exposure apparatus 2 is an apparatus that forms an electrostatic latent image by irradiating the photosensitive drums 1a to 1d with laser light while scanning. The laser beam is scanned in a direction (main scanning direction) perpendicular to the rotation direction (sub-scanning direction) of the photosensitive drums 1a to 1d. The exposure apparatus 2 has a laser scanning unit including a laser diode that is a light source of laser light and optical elements (lenses, mirrors, polygon mirrors, etc.) that guide the laser light to the photosensitive drums 1a to 1d.

  Further, around the photosensitive drums 1a to 1d, a charger such as a scorotron, a cleaning device, a static eliminator and the like are arranged. The cleaning device removes residual toner on the photosensitive drums 1a to 1d after the primary transfer, and the static eliminator neutralizes the photosensitive drums 1a to 1d after the primary transfer.

  The developing units 3a to 3d attach the toner cartridge filled with toners of four colors of cyan, magenta, yellow and black, and the toner conveyed from the toner hopper in the toner cartridge to the photosensitive drums 1a to 1d. A developing unit, and the toner is attached to the electrostatic latent images on the photosensitive drums 1a to 1d to form a toner image.

  The photosensitive drum 1a and the developing unit 3a develop magenta, the photosensitive drum 1b and the developing unit 3b develop cyan, and the photosensitive drum 1c and the developing unit 3c develop yellow. Then, black development is performed by the photosensitive drum 1d and the developing unit 3d.

  The intermediate transfer belt 4 is an annular image carrier (intermediate transfer member) that comes into contact with the photosensitive drums 1a to 1d and primarily transfers the toner images on the photosensitive drums 1a to 1d. The intermediate transfer belt 4 is stretched around the driving roller 5 and circulates in the direction from the contact position with the photosensitive drum 1d to the contact position with the photosensitive drum 1a by the driving force from the driving roller 5.

  The transfer roller 6 brings the conveyed paper into contact with the intermediate transfer belt 4 and secondarily transfers the toner image on the intermediate transfer belt 4 to the paper. The sheet on which the toner image has been transferred is conveyed to the fixing device 9 and the toner image is fixed on the sheet.

  The roller 7 has a cleaning brush, and the cleaning brush is brought into contact with the intermediate transfer belt 4 to remove the toner remaining on the intermediate transfer belt 4 after the transfer of the toner image onto the paper.

  The sensor 8 irradiates the intermediate transfer belt 4 with a light beam, and detects reflected light from the surface of the intermediate transfer belt 4 or a toner pattern on the surface. For example, the sensor 8 irradiates a predetermined region of the intermediate transfer belt 4 with light when detecting toner density, detects reflected light of the light, and outputs an electrical signal corresponding to the amount of light.

  FIG. 2 is a block diagram showing a part of the electrical configuration of the image forming apparatus according to the embodiment of the present invention. The image forming apparatus includes a print engine 11 and a controller 12.

  In FIG. 2, a print engine 11 is a circuit that controls the electrophotographic process and paper conveyance drive system and the exposure apparatus 2 shown in FIG. 1. The print engine 11 executes printing according to the image data from the controller 12. For example, the drive system of the paper transport is a motor that drives a roller that feeds the print paper, transports the print paper to the developing device and the fixing device 9 described above, and discharges the print paper after printing is completed. is there. For example, the drive system of the electrophotographic process is a motor that drives the photosensitive drums 1a to 1d, the intermediate transfer belt 4, and the like, a laser scanning motor of the exposure apparatus 2, and the like.

  The controller 12 supplies image data for each color after image processing such as color correction and halftoning to the print engine 11.

  The print engine 11 includes an exposure signal generation unit 21 and an exposure signal correction unit 22. The exposure signal generation unit 21 generates an exposure signal based on the image data from the controller 12. The exposure signal indicates whether or not each pixel is irradiated with light based on the image data from the controller 12.

  The exposure signal correction unit 22 corrects the exposure signal generated by the exposure signal generation unit 21. The exposure signal correction unit 22 specifies the distribution pattern of the electrostatic latent image based on the exposure signal before correction, specifies the electric field variability of the target pixel based on the distribution pattern of the electrostatic latent image, and determines the electric field variability. Based on this, the exposure signal is corrected, and the corrected exposure signal is supplied to the exposure apparatus.

  FIG. 3 is a block diagram showing the configuration of the exposure signal correction unit 22 in the first embodiment.

  In FIG. 3, the electrostatic latent image predicting unit 31 specifies a distribution pattern of the electrostatic latent image from the exposure signal. The electrostatic latent image predicting unit 31 specifies a distribution pattern of the electrostatic latent image by applying a low-pass filter to the distribution pattern of the exposure signal before correction. In the first embodiment, the low-pass filter is a Gaussian filter.

  FIG. 4 is a diagram illustrating an example of the filter coefficient of the electrostatic latent image prediction unit 31 in FIG. The electrostatic latent image predicting unit 31 determines a filter coefficient based on Gaussian variance values in the main scanning direction and the sub-scanning direction that are set in advance. The filter coefficient shown in FIG. 4 is a filter coefficient of a Gaussian filter having a Gaussian variance value of 0.81. The sum of the filter coefficients is approximately 1. This Gaussian dispersion value is specified based on the profile of the laser light emitted from the exposure apparatus 2.

  The output value of the electrostatic latent image prediction unit 31 for the target pixel (that is, the output value for the center pixel (i = 0, j = 0) in FIG. 4) is the exposure signal for each peripheral pixel (i, j). And the sum of the product of the value of and the filter coefficient for that pixel (i, j).

  The electric field fluctuation prediction unit 32 calculates the electric field fluctuation degree of the target pixel based on the distribution pattern of the electrostatic latent image obtained by the electrostatic latent image prediction unit 31. The electric field fluctuation prediction unit 32 specifies the electric field fluctuation degree of the target pixel based on the electric field intensity distribution pattern of each pixel in the electrostatic latent image distribution pattern. Here, the electric field intensity distribution pattern by each pixel is inversely proportional to the square of the distance from the pixel.

  FIG. 5 is a diagram illustrating an example of the filter coefficient of the electric field fluctuation prediction unit 32 in FIG. The filter coefficient for the target pixel (center pixel in FIG. 5) is 0, and the sum of the filter coefficients is approximately 1.

  The output value of the electric field fluctuation prediction unit 32 for the target pixel (that is, the output value for the center pixel in FIG. 5) is the output value of the electrostatic latent image prediction unit 31 for each peripheral pixel (i, j) and the pixel. A value obtained by subtracting the output value of the electrostatic latent image prediction unit 31 for the pixel of interest from the sum of the products of (i, j) and the filter coefficient is used.

  The multiplication unit 33 calculates the exposure signal correction amount by multiplying the electric field fluctuation degree of the target pixel obtained by the electric field fluctuation prediction unit 32 by a predetermined gain.

  The subtraction unit 34 subtracts the correction amount of the target pixel obtained by the multiplication unit 33 from the value for the target pixel in the exposure signal. Thereby, the exposure signal is corrected.

  The exposure signal correction unit 22 performs pulse width modulation and / or pulse amplitude modulation on the corrected exposure signal, operates the exposure apparatus 2 with the corrected exposure signal thus modulated, and photosensitive drums 1a to 1d. Controls the amount of light that is irradiated. In the pulse width modulation, a signal having a constant amplitude for a time corresponding to the value of the exposure signal for each pixel is generated. The period having the amplitude is set around the center of the scanning period by the exposure apparatus 2 corresponding to the pixel.

  In this way, the light irradiation time or light intensity within the exposure period corresponding to each pixel is determined corresponding to the corrected value of the exposure signal for that pixel.

  Next, the operation of the image forming apparatus will be described.

  In the print engine 11, when image data is supplied from the controller 12, the exposure signal generator 21 generates an exposure signal based on the image data.

  The exposure signal correction unit 22 corrects the exposure signal. Then, the print engine 11 operates the exposure device 2 with a pulse width and / or pulse amplitude corresponding to the corrected exposure signal value to irradiate the photosensitive drums 1a to 1d with light, thereby forming an electrostatic latent image. Let

  In the exposure signal correction unit 22, the electrostatic latent image prediction unit 31 sequentially holds the exposure signal before correction in a line buffer having a predetermined number of lines, and displays the pixel value of the exposure signal held in the line buffer. 4 is applied to calculate the electrostatic latent image level (corresponding to the negative charge amount) of the pixel of interest (center pixel).

  Next, the electric field fluctuation prediction unit 32 sequentially holds the output of the electrostatic latent image prediction unit 31 in a line buffer having a predetermined number of lines, and filters the values held in the line buffer as shown in FIG. Is applied to calculate the fluctuation amount of the electric field strength of the target pixel (center pixel).

  Then, the multiplication unit 33 multiplies the fluctuation amount of the electric field strength of the target pixel by a predetermined gain to calculate the correction amount for the target pixel. The gain value is determined in advance by experiments or the like.

  The correction amount is subtracted from the value of the exposure signal before correction of the target pixel by the subtracting unit 34, and the value of the exposure signal after correction is calculated.

  Even if the value of the exposure signal before correction is multi-valued (for example, binarized), the value of the exposure signal after correction is an intermediate value of a plurality of values that can be taken in multi-value conversion. Sometimes. Then, the pulse width and pulse amplitude (intensity) of light emitted from the exposure apparatus 2 are adjusted according to the value of the corrected exposure signal.

  In this manner, the distribution pattern of the electrostatic latent image due to the light irradiation by the exposure apparatus 2 and the distribution pattern of the electric field strength based on the distribution pattern of the electrostatic latent image are modeled, so that the edge effect can be accurately predicted. Therefore, the edge effect is accurately reduced. Further, since the original image data before binarization is not processed, the print image is not deteriorated due to the processing of the original image data.

  Here, a specific example related to the first embodiment is shown.

  First example.

  FIG. 6 is a diagram showing an example of a distribution pattern of exposure signal values before correction. FIG. 7 is a diagram illustrating an example of a distribution pattern of the electrostatic latent image obtained from the exposure signal of FIG. 6 by the electrostatic latent image prediction unit 31 according to the first embodiment. FIG. 8 is a diagram showing an example of a corrected exposure signal distribution pattern obtained from the exposure signal of FIG. 6 by the exposure signal correction unit 22 in the first embodiment.

  FIG. 9 is a diagram showing a simulation result of the distribution pattern of the electrostatic latent image by the exposure signal before correction shown in FIG. FIG. 10 is a diagram showing a simulation result of the distribution pattern of the electrostatic latent image by the exposure signal after the exposure signal of FIG. 6 is corrected by the exposure signal correction unit 22 in the first embodiment.

  The exposure signal is corrected as shown in FIGS. As a result, as shown in FIGS. 9 and 10, the distribution pattern of the electrostatic latent images actually formed on the photosensitive drums 1a to 1d is corrected. The distribution pattern of the electrostatic latent image shown in FIG. 7, FIG. 9, and FIG. 10 shows the distribution of the negative charge amount. Compared with FIG. 9 and FIG. The edge of the pattern is gentle.

  Second example.

  FIG. 11 is a diagram showing another example of a distribution pattern of exposure signal values before correction. FIG. 12 is a diagram illustrating an example of a distribution pattern of the electrostatic latent image obtained from the exposure signal of FIG. 11 by the electrostatic latent image predicting unit 31 according to the first embodiment. FIG. 13 is a diagram showing an example of a corrected exposure signal distribution pattern obtained from the exposure signal of FIG. 11 by the exposure signal correction unit 22 in the first embodiment.

  FIG. 14 is a diagram showing a simulation result of the distribution pattern of the electrostatic latent image by the exposure signal before correction shown in FIG. FIG. 15 is a diagram showing a simulation result of the distribution pattern of the electrostatic latent image by the exposure signal after the exposure signal of FIG. 11 is corrected by the exposure signal correction unit 22 in the first embodiment.

  The exposure signal is corrected as shown in FIGS. As a result, as shown in FIGS. 14 and 15, the distribution pattern of the electrostatic latent images actually formed on the photosensitive drums 1a to 1d is corrected. The distribution pattern of the electrostatic latent image shown in FIG. 12, FIG. 14, and FIG. 15 shows the distribution of the negative charge amount. Comparing FIG. 14 and FIG. 15, the distribution of the electrostatic latent image of FIG. The edge of the pattern is gentle.

  As described above, according to the first embodiment, the print engine 11 specifies the distribution pattern of the electrostatic latent image based on the exposure signal before correction, and the target pixel based on the distribution pattern of the electrostatic latent image. And the exposure signal is corrected based on the electric field variation, and the corrected exposure signal is supplied to the exposure apparatus 2.

  Thereby, since the distribution pattern of the electrostatic latent image and the electric field intensity distribution pattern based on the distribution pattern are modeled, the edge effect can be reduced while accurately drawing the edge portion.

  Further, according to the first embodiment, since the exposure amount by the exposure apparatus 2 is directly controlled, even if the value before the correction of the exposure signal for the edge portion is an intermediate value, the edge shape changes. Is less.

Embodiment 2. FIG.

  The image forming apparatus according to the second embodiment of the present invention has the same basic configuration as the image forming apparatus according to the first embodiment. However, the exposure signal correction unit 22 in the second embodiment is different from the exposure signal correction unit 22 in the first embodiment. Hereinafter, the exposure signal correction unit 22 according to the second embodiment will be described, and the other configuration of the image forming apparatus according to the second embodiment is the same as that of the first embodiment, and thus the description thereof will be omitted.

  FIG. 16 is a block diagram showing the configuration of the exposure signal correction unit 22 in the second embodiment. The electrostatic latent image prediction unit 31, the electric field fluctuation prediction unit 32, the multiplication unit 33, and the subtraction unit 34 in FIG. 16 are the same as those in the first embodiment (FIG. 3).

  In the exposure signal correction unit 22 according to the second embodiment, the multiplication unit 41 calculates the product of the output value of the electric field fluctuation prediction unit 32 and the output value of the electrostatic latent image prediction unit 31 for the target pixel, and the multiplication unit 33. Calculates the exposure signal correction amount by multiplying the output value of the multiplier 41 by a predetermined gain.

  Here, a specific example related to the second embodiment will be described.

  First example.

  FIG. 17 is a diagram showing an example of a corrected exposure signal distribution pattern obtained from the exposure signal of FIG. 6 by the exposure signal correction unit 22 according to the second embodiment. FIG. 18 is a diagram showing a simulation result of the distribution pattern of the electrostatic latent image by the exposure signal after the exposure signal of FIG. 6 is corrected by the exposure signal correction unit 22 in the second embodiment.

  Compared to the first embodiment (FIGS. 8 and 10), the electrostatic latent image level of isolated dots is improved in the second embodiment.

  Second example.

  FIG. 19 is a diagram showing an example of a corrected exposure signal distribution pattern obtained from the exposure signal of FIG. 11 by the exposure signal correction unit 22 according to the second embodiment. FIG. 20 is a diagram showing a simulation result of the distribution pattern of the electrostatic latent image by the exposure signal after the exposure signal of FIG. 11 is corrected by the exposure signal correction unit 22 in the second embodiment.

  As described above, according to the second embodiment, the print engine 11 multiplies the product of the electric field fluctuation degree and the value of the target pixel in the distribution pattern of the electrostatic latent image by the predetermined gain, and thereby corrects the exposure signal correction amount. Calculate

  This makes it possible to accurately draw a portion such as an isolated dot that is difficult to be developed with toner. As a result, it is possible to suppress the adhesion of toner to the area around the edge where there is no dot.

  Each embodiment described above is a preferred example of the present invention, but the present invention is not limited to these, and various modifications and changes can be made without departing from the scope of the present invention. It is.

  For example, the image forming apparatus according to each of the above embodiments is a color image forming apparatus, but may be a monochrome image forming apparatus.

  In each of the above embodiments, the number of dots in the exposure signal may be counted, and the toner consumption amount may be calculated based on the count value. According to the above-described embodiment, since the toner supply amount at the edge portion and the portion other than the edge is constant, the toner consumption amount can be accurately calculated from the count value of the number of dots in the exposure signal.

  The present invention is applicable to, for example, an electrophotographic image forming apparatus.

1a to 1d Photosensitive drum (an example of a photosensitive member)
2 Exposure device 11 Print engine (an example of a control unit)

Claims (9)

A photoreceptor,
An exposure device that irradiates the photosensitive member with light based on an exposure signal to form an electrostatic latent image; and
A controller for supplying the exposure signal to the exposure apparatus;
The control unit specifies a distribution pattern of the electrostatic latent image based on the exposure signal before correction, specifies an electric field variation degree of a target pixel based on the distribution pattern of the electrostatic latent image, and the electric field variation Correcting the exposure signal based on the degree, and supplying the corrected exposure signal to the exposure apparatus;
An image forming apparatus.   The image forming apparatus according to claim 1, wherein the control unit calculates a correction amount of the exposure signal by multiplying the electric field variation by a predetermined gain.   The control unit calculates a correction amount of the exposure signal by multiplying a product of the degree of electric field variation and a value of a target pixel in the distribution pattern of the electrostatic latent image by a predetermined gain. The image forming apparatus described.   The control unit specifies a distribution pattern of the electrostatic latent image by applying a low-pass filter to the distribution pattern of the exposure signal before correction. The image forming apparatus according to claim 1.   The image forming apparatus according to claim 4, wherein the low-pass filter is a Gaussian filter.   The said control part specifies the electric field variation degree of a focused pixel based on the electric field strength distribution pattern by each pixel in the distribution pattern of the said electrostatic latent image, The any one of Claims 1-5 characterized by the above-mentioned. 2. An image forming apparatus according to item 1.   2. The control unit according to claim 1, wherein the control unit performs pulse width modulation on the corrected exposure signal, and controls the amount of light applied to the photoconductor with the corrected exposure signal subjected to pulse width modulation. The image forming apparatus according to claim 1.   2. The control unit according to claim 1, wherein the control unit performs pulse amplitude modulation on the exposure signal after correction, and controls the amount of light applied to the photoconductor with the exposure signal after correction subjected to pulse amplitude modulation. The image forming apparatus according to claim 1. In an image forming method in an image forming apparatus, comprising: a photoconductor; and an exposure device that irradiates the photoconductor with light based on an exposure signal to form an electrostatic latent image.
Identify the distribution pattern of the electrostatic latent image based on the exposure signal before correction,
Identify the electric field variation of the pixel of interest based on the distribution pattern of the electrostatic latent image,
Correcting the exposure signal based on the electric field variation,
Supplying the exposure signal after correction to the exposure apparatus;
An image forming method.