JP2009168945A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of accurately and easily measuring a toner concentration or an amount of toner consumption in real time. <P>SOLUTION: A first counter 75 divides an image into a plurality of first small areas, which in turn are four pixels × four pixels, and counts written pixels in the first small area for each of the first small areas. Simultaneously, a second counter 76 obtains a second small area delayed horizontally and vertically relative to the first small area only by a fixed number of pixels, and counts the written pixels in the second small area. The arithmetic circuit 78 divides the sum of the written pixels in the first and second small areas respectively counted by the first and second counters 75 and 76 in half, and obtains a written pixel density and a value corresponding to the number of written pixels. The arithmetic circuit 78 integrates the values of the first small areas and obtains the integral value as an amount of toner consumption. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electrophotographic image forming apparatus that forms a visible image by developing a latent image on a latent image carrier with toner.

  Examples of this type of electrophotographic image forming apparatus include a copying machine, a printer, and a facsimile. In this image forming apparatus, an electrostatic latent image is formed on a photoconductor, the electrostatic latent image on the photoconductor is developed with toner, a toner image is formed on the photoconductor, and the toner image is removed from the photoconductor. The toner image is fixed on the recording paper by transferring to the recording paper and heating and pressurizing the recording paper.

  As a developing device for developing an electrostatic latent image, there is an apparatus using a two-component developer obtained by mixing toner and a carrier. In this developing device, a two-component developer is stored in a developing container, the two-component developer is supplied from the developing container to the photosensitive member, and the electrostatic latent image on the photosensitive member is developed with toner of the two-component developer. To do. Further, when the toner concentration is lowered due to the consumption of the toner of the two-component developer, the image quality is lowered. Therefore, the toner is replenished to keep the toner concentration substantially constant.

  Conventionally, for example, a patch-like electrostatic latent image having a predetermined image density is formed on an electrostatic latent image carrier such as a photosensitive drum, and developed to develop a patch-like visible image (toner image). The visible image is irradiated with the infrared light of the LED, the reflected light is received by the photodiode, and the density of the visible image is detected based on the received light output of the photodiode. The density of the detected visible image The toner of the two-component developer was replenished accordingly. Since the density of the visible image corresponds to the toner density of the two-component developer, the density of the visible image can be compared with a reference value to determine the toner density, and the toner can be determined according to the determination result. By controlling the replenishment amount, the toner density can be kept substantially constant.

  Alternatively, the image indicated by the image data is divided into a plurality of small areas, the number of write pixels visualized by toner is obtained for each small area, and the toner consumption is obtained based on the number of pixels of the write pixels. The toner was replenished by the amount consumed. A pixel that is visualized by toner is referred to as a writing pixel, and a white pixel that is not visible is referred to as a non-writing pixel.

  For example, as shown in FIG. 8, image data from the scanner 101 and the image generation circuit 102 is input to the image processing circuit 103, where the image data is processed, and then the image data is processed into the print processing unit 104 and the toner consumption counter. To 105. The print processing unit 104 forms an electrostatic latent image on the photosensitive member as described above, develops the electrostatic latent image on the photosensitive member with toner, and transfers the toner image from the photosensitive member to recording paper. The toner image is fixed on the recording paper. In addition, the toner consumption counter 105 receives the image data and also receives the horizontal synchronization signal and the vertical synchronization signal, and the image indicated by the image data is 4 × based on the synchronization timing of the horizontal synchronization signal and the vertical synchronization signal. It is divided into small areas of 4 pixels, the number of pixels to be written is obtained for each small area, the toner consumption amount is obtained based on the number of pixels of the writing pixel, and this toner consumption amount is converted into a toner supply mechanism (not shown). ).

In Patent Document 1, an image indicated by image data is divided into a plurality of determination areas, and for each determination area, the average density of the image in the determination area, the image type distinguished from the edge pattern of the image in the area, and the image type The spatial frequency and the like were measured, and the toner consumption was obtained from the measurement result.
Japanese Patent Laid-Open No. 06-11969

  However, when a patch-like visible image is formed as described above, the density of the visible image is detected, and the toner of the two-component developer is replenished according to the density of the visible image, the processing procedure is complicated. And the processing time became longer.

  Further, when the toner consumption amount is obtained based on the number of writing pixels as in the apparatus shown in FIG. 8, the toner consumption amount cannot be obtained accurately. This is because the toner consumption does not depend only on the number of pixels to be written and varies depending on other conditions.

  Further, in Patent Document 1, unless the number of image types to be measured is increased, the toner consumption cannot be measured accurately. However, it is considered that the measurement becomes more complicated and difficult as the number of image types is increased. In addition, since the image itself is originally a random pattern, even if the image is divided into a plurality of determination areas, it is considered difficult to measure the image type of the determination area, and implementation and achievement of the effect are not easy. .

  Accordingly, the present invention has been made in view of the above-described conventional problems, and an object thereof is to provide an image forming apparatus capable of accurately and easily measuring toner density or toner consumption in real time. To do.

  In order to solve the above problems, the present invention forms an image indicated by image data as a latent image on a latent image carrier, supplies toner to the latent image carrier, and uses the toner to form a latent image on the latent image carrier. In the image forming apparatus for visualizing the latent image, the image indicated by the image data is divided into a plurality of small areas, and the writing pixel density of the writing pixels visualized by the toner is obtained for each small area, and the writing pixel density is obtained. A calculation means for obtaining the toner consumption based on the calculation unit is provided.

  The computing means obtains the writing pixel density of the writing pixels visualized by toner for each of the small areas, obtains the image density or the number of writing pixels, and based on the writing pixel density and the image density or the number of writing pixels. The toner consumption is calculated.

  Further, the calculation means counts the first counting means for counting the number of write pixels in the small area, and the number of write pixels in other small areas shifted from the small area in the row direction or column direction of the arrangement of the pixels. The sum of the second counting means, the number of writing pixels counted by the first counting means and the number of writing pixels counted by the second counting means is obtained, and a value ½ of this sum is set as the writing pixel density and The number of pixels to be written is obtained.

  In addition, the calculation unit changes the shift amount of other small regions in the row direction or the column direction according to the resolution of the image indicated by the image data.

  Further, the arithmetic means changes the size of the small area according to the resolution of the image indicated by the image data.

  Further, the arithmetic means changes the amount of shift of other small regions in the row direction or the column direction according to the type of image indicated by the image data.

  Further, the computing means changes the size of the small area according to the type of image indicated by the image data.

  Further, the calculation means corrects either the number of write pixels counted by the first count means or the number of write pixels counted by the second count means by a weighting coefficient.

  Further, the image forming apparatus forms a color image composed of images of the respective colors indicated by the image data of the respective colors, and the calculation means obtains a toner consumption amount for each image of each color.

  According to such an image forming apparatus of the present invention, the image is divided into a plurality of small areas, and the writing pixel density of the writing pixels visualized by the toner is obtained for each small area, and the toner is based on the writing pixel density. Seeking consumption. A pixel that is visualized by toner is referred to as a writing pixel, and a white pixel that is not visible is referred to as a non-writing pixel.

  Here, the toner consumption varies depending on the writing pixel density. The writing pixel becomes an electrostatic latent image on the latent image carrier by laser beam irradiation. In the vicinity of the center of the irradiation spot where the irradiation intensity of the laser beam is the highest, the charging intensity of the electrostatic latent image of the writing pixel becomes maximum. Further, as the irradiation intensity of the laser beam is further away from the center, the charging intensity is weakened, and the charging intensity is reduced concentrically. Then, toner adhesion is large at a portion where the charging strength near the center is high, and the amount of toner adhesion decreases as the charging strength decreases away from the center.

  For this reason, for example, in the case of a single writing pixel, the toner consumption is large near the center of the writing pixel, and the toner consumption decreases as the distance from the center of the writing pixel becomes concentric.

  However, when a plurality of writing pixels are densely packed, the respective irradiation spots of the laser beam corresponding to each writing pixel approach each other, and the laser beam is irradiated repeatedly between the writing pixels. Compared to a single writing pixel, the charging intensity is not lowered around the center of the writing pixel, and the amount of toner attached is large. Accordingly, the toner consumption varies depending on the density of the writing pixels.

  Therefore, in the present invention, the writing pixel density is obtained for each small area, and the toner consumption amount is obtained based on the writing pixel density. As a result, the toner consumption can be accurately obtained.

  Further, since the toner consumption is obtained by the image data calculation process, the toner consumption can be obtained simultaneously with the development of the latent image by the toner, and the toner can be replenished immediately.

  Furthermore, since it is not necessary to determine the image pattern, type, etc., the processing procedure is simple and the processing time is short.

  Further, not only the writing pixel density but also the image density or the number of writing pixels may be obtained, and the toner consumption amount may be obtained based on the writing pixel density and the image density or the number of writing pixels. Since the toner consumption varies depending on the image density and the number of writing pixels, it is preferable to obtain the toner consumption based on the writing pixel density and the image density or the number of writing pixels.

  For example, the number of pixels to be written in the small area is counted by the first counting means, and the number of pixels to be written in the other small areas shifted from the small area in the row direction or the column direction of each pixel is counted by the second counting means. The sum of the number of writing pixels counted by the first counting means and the number of writing pixels counted by the second counting means is obtained, and a value ½ of this sum is obtained as the writing pixel density and the number of writing pixels. it can.

  In this case, it is preferable to change the shift amount of the other small areas in the row direction or the column direction or change the size of the small areas according to the resolution of the image. Alternatively, the shift amount of other small areas in the row direction or the column direction is changed or the size of the small areas is changed according to the type of image. The types of images include text, photographs, halftones (such as newspapers with gray paper).

  Further, if either the number of written pixels counted by the first counting means or the number of written pixels counted by the second counting means is corrected by the weighting coefficient, it becomes possible to obtain the toner consumption more accurately. .

  Furthermore, in an image forming apparatus that forms a color image, the amount of toner consumed is determined for each color image, that is, for each color toner.

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

  FIG. 1 is a cross-sectional view showing an embodiment of the image forming apparatus of the present invention. The image forming apparatus A records and forms an image of a document read by the document reading device B or an image received from the outside on a recording sheet in color or single color, and includes a laser exposure device 1, a developing device 2, and a photoreceptor. The drum 3, the charger 5, the cleaner device 4, the intermediate transfer belt device 8, the fixing device 12, the paper transport path S, the paper feed tray 10, the paper discharge tray 15, and the like.

  The image data handled in the image forming apparatus A uses data corresponding to a color image using each color of black (K), cyan (C), magenta (M), yellow (Y), or a single color (for example, black). This is in accordance with the monochrome image. Accordingly, the developing device 2 (2a, 2b, 2c, 2d), the photosensitive drum 3 (3a, 3b, 3c, 3d), the charger 5 (5a, 5b, 5c, 5d), the cleaner device 4 (4a, 4b, 4c and 4d) are provided in each of four types so as to form four types of latent images corresponding to the respective colors, a corresponding to black, b corresponding to cyan, c corresponding to magenta, and d corresponding to yellow. Four image stations are configured.

  The photoconductor drum 3 is disposed in the approximate center of the image forming apparatus A.

  The charger 5 is a charging means for uniformly charging the surface of the photosensitive drum 3 to a predetermined potential. In addition to a contact type roller type or brush type charger, a charger type charger is used. .

  The laser exposure apparatus 1 is a laser scanning unit (LSU) provided with a laser diode and a reflection mirror, which exposes the surface of a charged photosensitive drum 3 according to image data and statically responds to the surface according to the image data. An electrostatic latent image is formed.

  The developing device 2 develops the electrostatic latent image formed on the photosensitive drum 3 with (K, C, M, Y) toner. The cleaner device 4 removes and collects toner remaining on the surface of the photosensitive drum 3 after development and image transfer.

  The intermediate transfer belt device 8 disposed above the photosensitive drum 3 includes an intermediate transfer belt 7, an intermediate transfer belt driving roller 21, a driven roller 22, an intermediate transfer roller 6 (6a, 6b, 6c, 6d), and an intermediate A transfer belt cleaning device 9 is provided.

  The intermediate transfer belt drive roller 21, the intermediate transfer roller 6, the driven roller 22, etc. stretch and support the intermediate transfer belt 7, and move the intermediate transfer belt 7 in the direction of arrow C.

  The intermediate transfer roller 6 is rotatably supported in the vicinity of the intermediate transfer belt 7, is pressed against the photosensitive drum 3 via the intermediate transfer belt 7, and transfers the toner image on the photosensitive drum 3 to the intermediate transfer belt 7. A transfer bias is applied.

  The intermediate transfer belt 7 is provided so as to come into contact with the photosensitive drums 3a, 3b, 3c, and 3d, and the toner images on the surfaces of the photosensitive drums 3a, 3b, 3c, and 3d are sequentially superimposed on the intermediate transfer belt 7. Are transferred to form a color toner image (a toner image of each color). This transfer belt is formed in an endless belt shape using a film having a thickness of about 100 μm to 150 μm.

  The transfer of the toner image from the photosensitive drum 3 to the intermediate transfer belt 7 is performed by the intermediate transfer roller 6 that is in pressure contact with the back surface of the intermediate transfer belt 7. A high voltage transfer bias (a high voltage having a polarity (+) opposite to the toner charging polarity (−)) is applied to the intermediate transfer roller 6 in order to transfer the toner image. The intermediate transfer roller 6 is a roller whose base is a metal (for example, stainless steel) shaft having a diameter of 8 to 10 mm and whose surface is covered with a conductive elastic material (for example, EPDM, urethane foam, or the like). With this conductive elastic material, a high voltage can be uniformly applied to the recording paper.

  As described above, the toner images on the surfaces of the photosensitive drums 3a, 3b, 3c, and 3d are stacked on the intermediate transfer belt 7 to form a color toner image indicated by the image data. The toner images of the respective colors stacked in this way are transported together with the intermediate transfer belt 7 and transferred onto the recording paper by the secondary transfer device 11 that contacts the intermediate transfer belt 7.

  The intermediate transfer belt 7 and the transfer roller 11a of the secondary transfer device 11 are pressed against each other to form a nip region. Further, the transfer roller 11a of the secondary transfer device 11 has a voltage for transferring the toner image of each color on the intermediate transfer belt 7 onto a recording sheet (high polarity (+) opposite to the toner charge polarity (-)). Voltage) is applied. Further, in order to constantly obtain the nip region, either the transfer roller 11a of the secondary transfer device 11 or the intermediate transfer belt drive roller 21 is made of a hard material (metal or the like), and the other is a soft material such as an elastic roller. (Elastic rubber roller, foaming resin roller, etc.).

  In addition, the toner image on the intermediate transfer belt 7 may not be completely transferred onto the recording paper by the secondary transfer device 11, and the toner may remain on the intermediate transfer belt 7. Causes color mixing. Therefore, the residual toner is removed and collected by the intermediate transfer belt cleaning device 9. The intermediate transfer belt cleaning device 9 includes, for example, a cleaning blade that comes into contact with the intermediate transfer belt 7 as a cleaning member, and the back side of the intermediate transfer belt 7 is supported by a driven roller 22 at a portion where the cleaning blade comes into contact. .

  The paper feed tray 10 is a tray for storing recording paper, and is provided below the image forming unit of the image forming apparatus A. The paper discharge tray 15 provided on the upper side of the image forming unit is a tray for placing printed recording paper face down.

  Further, the image forming apparatus A is provided with an S-shaped sheet conveyance path S for sending the recording sheet in the sheet feeding tray 10 to the sheet discharge tray 15 via the secondary transfer apparatus 11 and the fixing apparatus 12. It has been. Along the sheet conveyance path S, a pickup roller 16, a registration roller 14, a fixing device 12, a conveyance roller for conveying a recording sheet, and the like are arranged.

  The transport rollers are small rollers for promoting and assisting the transport of the recording paper, and a plurality of transport rollers are provided along the paper transport path S. The pickup roller 16 is a call-in roller that is provided at the end of the paper feed tray 10 and supplies recording paper from the paper feed tray 10 to the paper transport path S one by one.

  The registration roller 14 temporarily stops the recording paper that has been conveyed, aligns the leading edge of the recording paper, and a color toner image on the intermediate transfer belt 7 in the nip area between the intermediate transfer belt 7 and the secondary transfer device 11. The recording paper is conveyed with good timing in accordance with the rotation of the photosensitive drum 3 and the intermediate transfer belt 7 so that the toner is transferred onto the recording paper.

  For example, the registration roller 14 records the leading end of the color toner image on the intermediate transfer belt 7 in the nip region between the intermediate transfer belt 7 and the secondary transfer device 11 based on a detection signal output from a pre-registration detection switch (not shown). The recording paper is conveyed so as to fit the leading end of the image forming range on the paper.

  The fixing device 12 includes a heat roller 31 and a pressure roller 32. The heat roller 31 and the pressure roller 32 sandwich and convey the recording paper.

  The heat roller 31 is controlled by the control unit so as to reach a predetermined fixing temperature based on a signal from a temperature detector (not shown), and the recording paper is thermocompression bonded together with the pressure roller 32. The toner image transferred onto the recording sheet is melted, mixed, and pressed to be thermally fixed to the recording paper.

  The recording paper after fixing the toner images of the respective colors is discharged onto the paper discharge tray 15 by the transport roller.

  On the other hand, in the document reading apparatus B, when the document is set on the document setting tray 41, the pickup roller 44 is pressed against the surface of the document to rotate, the document is pulled out from the tray 41, and the document passes between the suction roller 45 and the separation pad 46. Then, the sheets are separated one by one and then conveyed to the conveyance path 47.

  In this conveyance path 47, the leading edge of the document comes into contact with the registration roller 49, the leading edge of the document is aligned in parallel with the registration roller 49, and then the document is transported by the registration roller 49 and between the reading guide 51 and the reading glass 52. Pass through. At this time, the light of the light source of the first scanning unit 53 is irradiated on the surface of the document through the reading glass 52, and the reflected light is incident on the first scanning unit 53 through the reading glass 52. Then, the light is reflected by the mirrors of the second scanning units 53 and 54 and guided to the imaging lens 55, and an image on the surface of the original is formed on a CCD (Charge Coupled Device) 56 by the imaging lens 55. The CCD 56 reads an image on the document surface and outputs image data indicating the image on the document surface. Further, the document is conveyed by the conveyance roller 57 and is discharged to the paper discharge tray 59 via the paper discharge roller 58.

  In addition, it is possible to read a document placed on the platen glass 61. The registration roller 49, the reading guide 51, the paper discharge tray 59, and the like and the members above them are integrated into a cover body that is pivotally supported so as to be opened and closed on the back side of the document reading device. When the upper cover body is opened, the document table glass 61 is released, and a document can be placed on the document table glass 61. When the document is placed and the cover body is closed, the first scanning unit 53 exposes the surface of the document on the document table glass 61 while moving the first and second scanning units 53 and 54 in the sub-scanning direction. Reflected light from the document surface is guided to the imaging lens 55 by the first and second scanning units 53 and 54, and an image of the document surface is formed on the CCD 56 by the imaging lens 55. At this time, the first and second scanning units 53 and 54 are moved while maintaining a predetermined speed relationship with each other, and reflection of the document surface → the first and second scanning units 53 and 55 → the imaging lens 55 → the CCD 56 is performed. The positional relationship between the first and second scanning units 53 and 54 is always maintained so that the length of the optical path of the light does not change, and thereby the focus of the image on the document surface on the CCD 56 is always accurately maintained.

  The entire image of the original read in this way is sent and received as image data to the image forming apparatus A, and the image is recorded on the recording paper in the image forming apparatus A as described above.

  Next, a schematic configuration of the developing device 2 (2a, 2b, 2c, 2d) will be described with reference to FIG. The developing device 2 includes a developing container 23 that stores a two-component developer containing toner and a carrier, and the toner of the two-component developer is rubbed while the two-component developer is stirred and conveyed in the developing container 23. The charged toner is attached to the outer peripheral surface of the developing roller 24 and conveyed to the developing region D between the developing roller 24 and the photosensitive drum 3, and the electrostatic latent image on the photosensitive drum 3 is charged by the charged toner. Develop.

  In the two-component developer in the developing container 23, the toner weight ratio is usually set to about several percent. The carrier is obtained by coating the surface of magnetic particles with a resin coat layer that controls chargeability or suppresses adhesion of toner. Alternatively, a resin carrier in which magnetic fine powder is dispersed in resin particles can be used instead.

  The developing roller 24 has a rod-like multi-pole magnetized magnet fixed thereto, and a non-magnetic sleeve (aluminum alloy, stainless steel, etc.) is rotatably supported around the multi-pole magnetized magnet. While rotating, the two-component developer is attracted and carried on the outer periphery of the sleeve by the magnetic force of the magnet.

  With the rotation of the sleeve, the layer thickness regulating member 25 regulates the layer thickness of the two-component developer on the outer periphery of the sleeve, and then the two-component developer layer on the outer periphery of the sleeve is moved to the development region D between the sleeve and the photosensitive drum 3. And the toner of the two-component developer layer on the outer periphery of the sleeve is attached to the electrostatic latent image on the surface of the photosensitive drum 3.

  By the way, if the toner concentration decreases due to the consumption of the toner of the two-component developer, the image quality deteriorates. Therefore, it is necessary to accurately supply the toner to the developing container 23 and keep the toner concentration of the two-component developer substantially constant. There is. For this reason, the amount of toner consumption is accurately obtained, and the toner is replenished by the amount of consumption. Since toner adheres to the electrostatic latent image on the surface of the photosensitive drum 3, the amount of toner consumption can be obtained based on image data indicating an image (electrostatic latent image).

  In this embodiment, the image indicated by the image data is divided into a plurality of small areas, and for each small area, values corresponding to the write pixel density and the number of write pixels of the write pixels visualized by the toner are obtained. The integrated value is obtained as the toner consumption amount. A pixel that is visualized by toner is referred to as a writing pixel, and a white pixel that is not visible is referred to as a non-writing pixel.

  Here, the toner consumption varies not only with the number of pixels to be written, but also with the density of the pixels to be written. The writing pixel becomes an electrostatic latent image on the photosensitive drum 3 by the laser beam irradiation from the laser exposure apparatus 1. In the vicinity of the center of the irradiation spot where the irradiation intensity of the laser beam is the highest, the charging intensity of the electrostatic latent image of the writing pixel becomes maximum. Further, the further away from the center of the laser beam irradiation spot, the lower the irradiation intensity of the laser beam and the lower the charging intensity concentrically. Further, the toner adhesion amount is large in the portion where the charging strength is high near the center, and the toner adhesion amount decreases as the charging strength decreases away from the center.

  For example, in FIGS. 3A and 3B, the writing pixel is P, the irradiation spot of the laser beam irradiated to write the writing pixel P is S, and the vicinity of the center where the irradiation intensity of the laser beam is high is S1. Let S2 be the periphery where the laser beam irradiation intensity is low. As shown in FIG. 3A, when the writing pixels P in the small area are spaced apart from each other, the irradiation spots S of the writing pixels P are also separated from each other. Thus, the toner adhesion amount of the writing pixel P is determined only by the charging intensity of the irradiation spot S of the writing pixel P. Therefore, the toner consumption amount can be obtained by simply integrating the toner adhesion amount of each writing pixel P.

  However, when the writing pixels P are dense as shown in FIG. 3B, the irradiation spots S corresponding to the writing pixels P approach each other, and the irradiation spots S overlap each other. . For this reason, the charge intensity is also high in the space between the write pixels P (the periphery S2 of the write pixel P). Compared with the scattered write pixels P as shown in FIG. The amount of toner attached in S2 increases.

  In FIGS. 3A and 3B, the writing pixel P and the irradiation spot S are shown in a simplified manner. However, as the plurality of writing pixels P (irradiation spots S) approach each other, the periphery of each writing pixel P is increased. The amount of toner adhesion increases. For example, the writing pixels P are closer in either the horizontal direction (the row direction of the pixel matrix) or the vertical direction (the column direction of the pixel matrix) than the writing pixels P are scattered apart. The toner adhesion amount is larger when the toner adhesion amount is larger and each writing pixel P is closer in either the horizontal direction or the vertical direction. For this reason, it can be said that the toner consumption varies not only according to the number of pixels to be written but also according to the density of the pixels to be written.

  Furthermore, when calculating the toner consumption of the entire image by integrating the toner consumption of each small area, consider not only the toner consumption within the small area but also the toner consumption near the boundary between the small areas. There is a need to. As shown in FIGS. 3C and 4, even if the writing pixel density in the small region E is low, the writing pixel density between the small region E and another small region E adjacent to the small region E is low. This can be expensive.

  Therefore, in the present embodiment, for each small region E, the number of pixels to be written, the pixel density in the small region E, and the pixel density around the small region E are considered, and the writing pixel density and the number of writing pixels related to the small region E are set. Find the corresponding value. Accordingly, if the values of the small areas are integrated and the integrated value is obtained as the toner consumption, the toner consumption can be accurately obtained.

  FIG. 5 is a block diagram illustrating a configuration of a control system for obtaining the toner consumption amount. In FIG. 4, a document reading device B (also shown in FIG. 1) reads a document image and outputs image data representing the document image. The image generation circuit 71 outputs image data received from the outside or image data read from a storage device.

  The image processing circuit 72 receives image data from the document reading device B and the image generation circuit 71, performs various image processing on the image data, and outputs the image data to the print processing unit 73 and the toner consumption counter 74. To do. At the same time, the image processing circuit 72 outputs a horizontal synchronization signal and a vertical synchronization signal synchronized with the image data to the toner consumption counter unit 74.

  The feature amount extraction circuit 72 a of the image processing circuit 72 determines whether the resolution of the image indicated by the image data is 600 dpi or 1200 dpi, and outputs the determined resolution of the image to the toner consumption counter 74. To do.

  The print processing unit 73 corresponds to the laser exposure device 1, the developing device 2, the photosensitive drum 3, the charger 5, the cleaner device 4, the intermediate transfer belt device 8, the fixing device 12 and the like in FIG. The laser exposure apparatus 1 receives image data from the image processing circuit 72, irradiates the surface of the photosensitive drum 3 with a laser beam, and writes an image indicated by the image data on the surface of the photosensitive drum 3 as an electrostatic latent image. Include. The electrostatic latent image is developed by the developing device 2 to form a toner image on the photosensitive drum 3, the toner image is transferred to the recording paper, and the toner image on the recording paper is fixed by the fixing device 12. .

  When the toner consumption counter 74 receives the image data, the horizontal synchronization signal, and the vertical synchronization signal from the image processing circuit 72, the toner consumption counter unit 74 generates a plurality of images indicated by the image data based on the synchronization timing of the horizontal synchronization signal and the vertical synchronization signal. The values corresponding to the writing pixel density and the number of writing pixels are obtained for each small region, the values of the small regions are integrated, and the integrated value is obtained as the toner consumption amount.

  Further, when the resolution of the image is input from the feature amount extraction circuit 72a of the image processing circuit 72, the toner consumption amount counter unit 74 sets the size of the small area in accordance with the resolution of the image. For example, when the image resolution is 600 dpi, the size of the small area is set to 8 pixels × 8 pixels, and when the image resolution is 1200 dpi, the size of the small area is set to 4 pixels × 4 pixels. .

  FIG. 6 is a block diagram showing a configuration of the toner consumption counter unit 74. As shown in FIG. 6, the toner consumption counter 74 includes a first counter 75, a second counter 76, a delay adjustment circuit 77, and an arithmetic circuit 78.

  The first counter 75 inputs and sets the size of the small area from the image processing circuit 72. The first counter 75 receives the image data, the horizontal synchronization signal, and the vertical synchronization signal from the image processing circuit 72, and based on the synchronization timing of the horizontal synchronization signal and the vertical synchronization signal, the first counter 75 converts the image indicated by the image data. Dividing into a plurality of first small areas, the number of write pixels is obtained for each small area.

  The second counter 76 inputs and sets the size of the small area from the image processing circuit 72. The second counter 76 receives the image data from the image processing circuit 72 and also receives the horizontal synchronization signal and the vertical synchronization signal from the image processing circuit 72 via the delay adjustment circuit 77. Based on the synchronization timing of the delayed horizontal synchronization signal and vertical synchronization signal, the image indicated by the image data is divided into a plurality of second small areas, and the number of pixels to be written is obtained for each second small area.

  The delay adjustment circuit 77 is instructed by a CPU (not shown) that controls the image forming apparatus A in a horizontal direction (a pixel matrix row direction) and a vertical direction (a pixel matrix column direction). The horizontal synchronizing signal and the vertical synchronizing signal are delayed by the delay amount in the horizontal direction and the vertical direction and then added to the second counter 76. The second counter 76 divides the image into a plurality of second small areas on the basis of the delayed horizontal synchronization signal and vertical synchronization signal, thereby horizontally and vertically with respect to the first small area. It is possible to set a second small region that is shifted in pixel units.

  The arithmetic circuit 78 calculates the sum of the number of write pixels in the first small area counted by the first counter 75 and the number of write pixels in the second small area counted by the second counter 76 for each first small area. And a value obtained by halving the sum is obtained as a value corresponding to the writing pixel density and the number of writing pixels. Then, the arithmetic circuit 78 integrates the values of the first small areas, obtains the integrated value as a toner consumption amount consumed for developing the image indicated by the image data, and calculates the toner consumption amount as the image consumption amount. Output to the CPU of the forming apparatus A.

  For example, it is assumed that the resolution of the image is 1200 dpi and the small area is set to 4 pixels × 4 pixels. In this case, when the first counter 75 receives the image data from the image processing circuit 72 and also receives the horizontal synchronization signal and the vertical synchronization signal, the first counter 75 uses the image data based on the synchronization timing of the horizontal synchronization signal and the vertical synchronization signal. The displayed image is divided into a plurality of first small areas each consisting of 4 pixels × 4 pixels, and the writing pixels in the first small area are obtained for each first small area, and the writing pixels in the first small area are counted. . At the same time, the second counter 76 obtains a second small region delayed by a certain number of pixels in the horizontal direction and the vertical direction with respect to the first small region based on the synchronization timing of the horizontal synchronizing signal and the vertical synchronizing signal, The writing pixels in the small area are obtained, and the writing pixels in the second small area are counted.

  The arithmetic circuit 78 calculates the sum of the number of write pixels in the first small area counted by the first counter 75 and the number of write pixels in the second small area counted by the second counter 76 for each first small area. Is ½, and values corresponding to the writing pixel density and the number of writing pixels are obtained. Then, the arithmetic circuit 78 integrates the values of the first small areas, obtains the integrated value as a toner consumption amount, and outputs the toner consumption amount to the CPU of the image forming apparatus A.

  The toner consumption thus obtained is an accurate one reflecting the number of pixels to be written in the small area, the writing pixel density in the small area, and the writing pixel density near the boundary of each small area.

  When the image resolution is 600 dpi, the small area size is set to 8 pixels × 8 pixels, and when the image resolution is 1200 dpi, the small area size is set to 4 pixels × 4 pixels. Therefore, the toner consumption can be accurately obtained even if the resolution of the image is changed.

  Further, since the toner consumption amount is obtained by the calculation processing of the image data, the toner consumption amount can be obtained simultaneously with the development of the latent image with the toner, and the toner can be replenished immediately.

  Moreover, since it is not necessary to determine an image pattern or type as in Patent Document 1, the processing procedure is simple, and the processing time is short.

  Such toner consumption is determined for each color toner. As described above, in the image forming apparatus A, black (K), cyan (C), magenta (M), and yellow (Y) image stations are provided, and toner is consumed for each image station. Or replenished. Therefore, it is necessary to determine the toner consumption amount for each color toner. Therefore, the toner consumption counter unit 74 of FIG. 5 is provided for each toner of each color, and the image data of each color is output from the image processing circuit 72 to each toner consumption counter unit 74, and each toner consumption counter unit 74 is provided. Thus, the toner consumption of each color is obtained.

  By the way, in the present embodiment, the size of the small area is changed according to the resolution of the image, but the shift amount of the first and second small areas may be changed according to the resolution of the image. Thereby, even if the resolution of the image is changed, the toner consumption amount can be obtained more accurately. The shift amount between the first and second small regions is the shift amount in the horizontal direction or the vertical direction, but the shift amount may be set so that the first and second small regions overlap each other. The shift amount may be set so that the two small regions are adjacent to each other or the first and second regions are separated from each other.

  Also, the weighting coefficient is set according to the resolution of the image, and the number of write pixels in the first small area counted by the first counter 75 and the number of write pixels in the second small area counted by the second counter 76. A value obtained by accumulating a weighting coefficient in at least one of the two and halving the sum of the number of write pixels may be obtained as a value corresponding to the write pixel density and the write pixel number. For example, as shown in FIG. 7, a weighting coefficient is set by the CPU of the image forming apparatus A, and the weighting coefficient is output from the CPU to the arithmetic circuit 78. A weighting coefficient is integrated into at least one of the number of write pixels in the two small areas. Thereby, even if the resolution of the image is changed, the toner consumption amount can be accurately obtained.

  Further, instead of setting the size of the small area according to the resolution of the image, the type of the image indicated by the image data may be determined, and the size of the small area may be set according to the type of the image.

  The types of images include text, photographs, halftones (such as newspapers with gray paper). When the image type is text, the density of the image is binary (white or black), and the density of the black portion is always clipped at the highest density. The density of the writing pixel does not change greatly, and the toner consumption depends more on the number of writing pixels than the writing pixel density.

  When the image type is a photograph or a halftone, since the density of the pixel is an intermediate density, the influence of the density of other adjacent pixels increases, and as the writing pixel density increases, the writing pixel density increases. The toner consumption is dependent on both the writing pixel density and the number of writing pixels.

  Therefore, the size of the small area is set according to the type of image. For example, when an original image is read and copied by the original reading device B, the type of the image is determined depending on whether the original is a character, a photograph, a halftone, or the like. The feature amount extraction circuit 72 a determines the type of image based on the image data indicating the image of the document, and outputs this image type to the toner consumption amount counter unit 74. When the type of image from the feature amount extraction circuit 72a is input, the toner consumption amount counter unit 74 sets the size of the small area in accordance with the type of image.

  For example, when the image type is a photograph or a halftone, the size of the small area is set small, and the writing pixel density of each small area or each small area is smaller than the toner consumption obtained by the toner consumption counter 74. The writing pixel density in the vicinity of the boundary of the region is greatly reflected.

  Alternatively, similarly to the resolution of the image, the shift amount of the first and second small regions may be changed according to the type of the image. In addition, a weighting coefficient is set according to the type of image, and the number of write pixels in the first small area counted by the first counter 75 and the number of write pixels in the second small area counted by the second counter 76. A value obtained by accumulating a weighting coefficient in at least one of the two and halving the sum of the number of write pixels may be obtained as a value corresponding to the write pixel density and the write pixel number.

  Furthermore, the size of the small area, the shift amount between the first and second small areas, and the weighting coefficient may be set according to the resolution and type of the image.

  Also, the image density may be obtained for each first small area, and the toner consumption amount may be obtained in consideration of the image density. For example, for each first small area, the image density of the first small area is obtained, a coefficient corresponding to this image density is multiplied by a value corresponding to the writing pixel density and the number of writing pixels, and a correction value based on the image density is obtained. You may ask. Then, the correction values of the respective first small areas are integrated, and this integrated value is obtained as the toner consumption amount. In particular, in a multi-value image, correction based on the image density of a small region is useful.

  Note that the present invention can be applied not only to a color image forming apparatus but also to a monochrome-only image forming apparatus.

1 is a cross-sectional view showing an embodiment of an image forming apparatus of the present invention. FIG. 2 is a cross-sectional view schematically showing a developing device in the image forming apparatus of FIG. 1. (A) is a figure which shows each writing pixel scattered apart, (b) is a figure which shows each writing pixel densely, (c) is the density of the writing pixel between each adjacent small area | region becoming high. It is a figure which shows a state. It is a figure which shows the state from which the density of the writing pixel became high between each adjacent small area | region. FIG. 2 is a block diagram illustrating a configuration of a control system for obtaining toner consumption in the image forming apparatus of FIG. 1. FIG. 6 is a block diagram illustrating a configuration of a toner consumption counter unit in FIG. 5. FIG. 10 is a block diagram illustrating a modified example of a toner consumption amount counter unit. FIG. 10 is a block diagram illustrating a configuration of a control system for obtaining toner consumption in a conventional image forming apparatus.

Explanation of symbols

A Image forming apparatus B Document sketching apparatus S Paper conveyance path 1 (1a, 1b, 1c, 1d) Laser exposure apparatus 2 (2a, 2b, 2c, 2d) Developing apparatus 3 (3a, 3b, 3c, 3d) Photoconductor Drum 4 (4a, 4b, 4c, 4d) Cleaner device 5 (5a, 5b, 5c, 5d) Charger 7 Intermediate transfer belt 8 Intermediate transfer belt device 10 Paper feed tray 11 Secondary transfer device 12 Fixing device 15 Paper discharge tray 41 Document setting tray 44 Pickup roller 53 First scanning unit 54 Second scanning unit 55 Imaging lens 56 CCD
71 Image generation circuit 72 Image processing circuit 73 Print processing unit 74 Toner consumption counter 75 First counter 76 Second counter 77 Delay adjustment circuit 78 Arithmetic circuit

Claims (9)

In an image forming apparatus that forms an image indicated by image data as a latent image on a latent image carrier, supplies toner to the latent image carrier, and visualizes the latent image on the latent image carrier with toner.
Computing means for dividing an image indicated by the image data into a plurality of small areas, obtaining a write pixel density of a write pixel visualized by toner for each small area, and obtaining a toner consumption amount based on the write pixel density; An image forming apparatus comprising the image forming apparatus.   The computing means obtains the writing pixel density of the writing pixels visualized by toner for each of the small areas, obtains the image density or the number of writing pixels, and calculates the toner based on the writing pixel density and the image density or the number of writing pixels. An image forming apparatus characterized by obtaining a consumption amount.   The arithmetic means counts the first counting means for counting the number of write pixels in the small area, and the second count for counting the number of write pixels in the other small areas shifted from the small area in the row direction or column direction of the arrangement of the pixels. The sum of the counting means, the number of writing pixels counted by the first counting means and the number of writing pixels counted by the second counting means is obtained, and a value ½ of this sum is set as the writing pixel density and the writing pixel. The image forming apparatus according to claim 1, wherein the image forming apparatus is obtained as a number.   The image forming apparatus according to claim 3, wherein the calculation unit changes a shift amount of another small region in the row direction or the column direction according to a resolution of an image indicated by the image data. .   The image forming apparatus according to claim 1, wherein the calculation unit changes a size of the small area according to a resolution of an image indicated by the image data.   The image forming apparatus according to claim 3, wherein the arithmetic unit changes a shift amount of another small region in the row direction or the column direction according to a type of an image indicated by the image data. .   The image forming apparatus according to claim 1, wherein the calculation unit changes a size of the small area according to a type of an image indicated by the image data.   4. The calculation unit according to claim 3, wherein the calculation unit corrects either the number of write pixels counted by the first count unit or the number of write pixels counted by the second count unit by a weighting coefficient. Image forming apparatus. The image forming apparatus forms a color image composed of an image of each color indicated by the image data of each color,
The image forming apparatus according to claim 1, wherein the calculation unit obtains a toner consumption amount for each color image.

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