JP2012150182A - Image forming apparatus and calculation method for the amount of toner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus employing an electrophotographic system that accurately derives the toner consumption.SOLUTION: An image forming apparatus employing an electrophotographic system includes a toner amount calculation unit 22 that specifies a distribution pattern of an electrostatic latent image based on an exposure signal for controlling an exposure device 2, specifies the intensity of an electric field of a pixel of interest based on the distribution pattern of an electrostatic latent image, and specifies the toner consumption corresponding to the intensity of an electric field.

Description

  The present invention relates to an image forming apparatus and a toner amount calculation method.

  An electrophotographic image forming apparatus such as a printer or a multifunction peripheral forms an image by taking out toner from a toner cartridge. Some of such electrophotographic image forming apparatuses measure toner consumption. Usually, the toner consumption is indirectly measured from image data or the like.

  In an electrophotographic image forming apparatus, an electrostatic latent image is formed on a photosensitive drum or the like. An edge electric field is generated at the boundary between the dot-exposed portion and the dot-free portion of the electrostatic latent image, and toner is consumed more than necessary. This phenomenon is called an edge effect. For this reason, various methods for calculating the toner consumption in consideration of the edge effect have been proposed (see, for example, Patent Document 1). In the apparatus described in Patent Document 1, the toner consumption is calculated in consideration of the appearance frequency of edges.

  Also, in a certain image forming apparatus, the potential of the pixel of interest is calculated in consideration of the exposure of the laser light to the peripheral pixels, and the toner consumption is calculated from the potential (see, for example, Patent Document 2).

JP 2006-276422 A JP 2009-145667 A

  However, since the image forming apparatus described in Patent Document 1 does not consider the influence from peripheral pixels of the edge, there is a possibility that the toner consumption amount may not be accurately calculated. In the image forming apparatus described in Patent Document 2 described above, although the potential of the pixel of interest is calculated in consideration of the exposure of the laser light to the peripheral pixels, an electrostatic latent image (that is, charge) formed in the peripheral pixels is calculated. ) Is not considered.

  SUMMARY An advantage of some aspects of the invention is that it provides an image forming apparatus and a toner amount calculation method in which a toner consumption amount is accurately derived.

  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 photosensitive member, an exposure device that irradiates the photosensitive member with light based on an exposure signal to form an electrostatic latent image, and a toner amount calculation unit that calculates a toner consumption amount based on the exposure signal. With. The toner amount calculation unit specifies the distribution pattern of the electrostatic latent image based on the exposure signal, specifies the electric field strength of the target pixel based on the distribution pattern of the electrostatic latent image, and the toner corresponding to the electric field strength. Identify consumption.

  As a result, the toner consumption amount is specified in consideration of the electric field strength of the target pixel due to the distribution pattern of the electrostatic latent image spreading in the peripheral pixels, and thus the toner consumption amount is accurately derived.

  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 toner amount calculation unit specifies a distribution pattern of the electrostatic latent image by applying a low-pass filter to the distribution pattern of the 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 above-described 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 toner amount calculation unit specifies the electric field strength of the pixel of interest based on the electric field strength distribution pattern of each pixel in the electrostatic latent image distribution pattern.

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

  A toner amount calculation method according to the present invention is a toner amount calculation 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. The distribution pattern of the electrostatic latent image is specified based on the exposure signal, the electric field strength of the target pixel is specified based on the distribution pattern of the electrostatic latent image, and the toner consumption corresponding to the electric field strength is specified.

  As a result, the toner consumption amount is specified in consideration of the electric field strength of the target pixel due to the distribution pattern of the electrostatic latent image spreading in the peripheral pixels, and thus the toner consumption amount is accurately derived.

  According to the present invention, the toner consumption can be accurately calculated.

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 the configuration of the toner amount calculation unit in FIG. 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 illustrating an example of a correspondence relationship between the electric field strength and the toner consumption in the conversion unit in FIG. FIG. 7 is a diagram illustrating an example of a distribution pattern of exposure signal values. FIG. 8 is a diagram showing an example of a distribution pattern of the electrostatic latent image obtained from the exposure signal of FIG. 7 by the electrostatic latent image prediction unit in FIG. 9 is a diagram showing an example of an electric field intensity distribution obtained from the exposure signal in FIG. 7 by the toner amount calculation unit in FIG. FIG. 10 is a diagram showing another example of the distribution pattern of exposure signal values. FIG. 11 is a diagram showing an example of a distribution pattern of the electrostatic latent image obtained from the exposure signal of FIG. 10 by the electrostatic latent image prediction unit in FIG. FIG. 12 is a diagram showing an example of an electric field intensity distribution obtained from the exposure signal in FIG. 10 by the toner amount calculation unit in FIG.

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

  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 a toner amount calculation 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 print engine 11 operates the exposure apparatus 2 with this exposure signal.

  The toner amount calculation unit 22 calculates a toner consumption amount that accompanies printing by the image forming apparatus. Further, the toner amount calculation unit 22 calculates the remaining amount of toner in the toner cartridge from the toner consumption amount. Further, the toner amount calculation unit 22 displays the integrated value of the toner consumption amount and the toner remaining amount on an operation panel (not shown), or displays a warning message on the operation panel (not shown) when the toner remaining amount is low. I will let you.

  The toner amount calculation unit 22 specifies the distribution pattern of the electrostatic latent image based on the exposure signal, specifies the electric field strength of the target pixel based on the distribution pattern of the electrostatic latent image, and consumes toner corresponding to the electric field strength. Specify the amount.

  FIG. 3 is a block diagram showing the configuration of the toner amount calculation unit 22 in FIG.

  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. In this 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 multiplies the electric field variation degree of the target pixel obtained by the electric field variation prediction unit 32 by a predetermined gain.

  The addition unit 34 calculates the sum of the value obtained by the multiplication unit 33 and the output value of the electrostatic latent image prediction unit 31 as the electric field strength of the target pixel for the target pixel.

  The conversion unit 35 converts the electric field intensity value of the target pixel obtained by the addition unit 34 into the toner consumption amount for the target pixel. The conversion unit 35 has a lookup table, for example, and refers to the lookup table to derive the toner consumption amount.

  The toner counter 36 calculates the cumulative value of the toner consumption amount for each page or when the toner cartridge is replaced based on the toner consumption amount information for each pixel obtained from the conversion unit 35.

  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.

  Then, the exposure signal is supplied to the exposure device 2, and the exposure device 2 irradiates the photosensitive drums 1a to 1d with light based on the exposure signal to form an electrostatic latent image.

  On the other hand, in the print engine 11, the exposure signal is supplied to the toner amount calculation unit 22, and the toner amount calculation unit 22 calculates the toner consumption amount based on the exposure signal.

  In the toner amount calculation unit 22, the electrostatic latent image prediction unit 31 sequentially holds the exposure signal in a line buffer having a predetermined number of lines, and the pixel values of the exposure signal held in the line buffer are shown in FIG. By applying such a filter, the electrostatic latent image level (corresponding to the negative charge amount) of the target pixel (center pixel) is calculated.

  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 multiplier 33 multiplies the fluctuation amount of the electric field strength of the target pixel by a predetermined gain. The gain value is determined in advance by experiments or the like.

  The output value of the multiplication unit 33 is added to the output value of the electrostatic latent image prediction unit 31 for the target pixel by the addition unit 34, and the electric field strength of the target pixel is calculated.

  Then, the conversion unit 35 calculates a toner consumption amount corresponding to the electric field strength of the target pixel and supplies it to the toner counter 36. The toner counter 36 updates the accumulated value of the toner consumption amount based on the toner consumption amount of the target pixel.

  FIG. 6 is a diagram illustrating an example of a correspondence relationship between the electric field strength and the toner consumption in the conversion unit 35 in FIG. The electric field strength in FIG. 6 is a value normalized by the electric field strength at the time of solid coating (that is, the value when the electric field strength at the time of solid coating is 1). Further, the toner consumption in FIG. 6 is a value normalized by the toner consumption per pixel at the time of solid coating (that is, the value when the toner consumption at the time of solid coating is 1).

  Here, a specific example will be described.

  First example.

  FIG. 7 is a diagram illustrating an example of a distribution pattern of exposure signal values. FIG. 8 is a diagram showing an example of a distribution pattern of the electrostatic latent image obtained from the exposure signal of FIG. 7 by the electrostatic latent image predicting unit 31 in FIG. FIG. 9 is a diagram showing an example of an electric field intensity distribution obtained from the exposure signal in FIG. 7 by the toner amount calculation unit 22 in FIG.

  As shown in FIG. 9, the location where the edge effect occurs is specified. Therefore, it is possible to count the toner consumption amount corresponding to it.

  Second example.

  FIG. 10 is a diagram showing another example of the distribution pattern of exposure signal values. FIG. 11 is a diagram illustrating an example of a distribution pattern of the electrostatic latent image obtained from the exposure signal of FIG. 10 by the electrostatic latent image predicting unit 31 in FIG. FIG. 12 is a diagram showing an example of an electric field intensity distribution obtained from the exposure signal of FIG. 10 by the toner amount calculation unit 22 in FIG.

  As shown in FIG. 12, the location where the edge effect occurs is specified. Therefore, it is possible to count the toner consumption amount corresponding to it.

  As described above, according to the above-described embodiment, the toner amount calculation unit 22 specifies the distribution pattern of the electrostatic latent image based on the exposure signal, and the electric field of the target pixel based on the distribution pattern of the electrostatic latent image. The intensity is specified, and the toner consumption corresponding to the electric field intensity is specified.

  As a result, the toner consumption amount is specified in consideration of the electric field strength of the target pixel due to the distribution pattern of the electrostatic latent image spreading in the peripheral pixels (that is, the charge distribution of the peripheral pixels). To be derived.

  The above-described embodiments are preferred examples 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. is there.

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

  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 22 Toner amount calculator

Claims (5)

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 toner amount calculation unit for calculating a toner consumption amount based on the exposure signal,
The toner amount calculation unit identifies the distribution pattern of the electrostatic latent image based on the exposure signal, identifies the electric field strength of the target pixel based on the distribution pattern of the electrostatic latent image, and corresponds to the electric field strength Identifying the amount of toner consumed,
An image forming apparatus.   The image forming apparatus according to claim 1, wherein the toner amount calculation unit specifies a distribution pattern of the electrostatic latent image by applying a low-pass filter to the distribution pattern of the exposure signal.   The image forming apparatus according to claim 2, wherein the low-pass filter is a Gaussian filter.   The toner amount calculation unit specifies the electric field strength of the pixel of interest based on an electric field strength distribution pattern by each pixel in the distribution pattern of the electrostatic latent image. The image forming apparatus according to claim 1. In a toner amount calculation method in an image forming apparatus comprising: a photosensitive member; and an exposure device that irradiates the photosensitive member with light based on an exposure signal to form an electrostatic latent image.
Identify a distribution pattern of the electrostatic latent image based on the exposure signal;
Identify the electric field strength of the pixel of interest based on the distribution pattern of the electrostatic latent image,
Identifying a toner consumption corresponding to the electric field strength;
A toner amount calculation method characterized by the above.