Image forming apparatus

Abstract

To provide a technique that allows simple and accurate acquisition of toner consumption.SOLUTION: An image forming apparatus comprises: a pixel number acquisition unit that acquires, from image information, the number of print pixels in which the brightness of exposure is equal to or more than a predetermined level, of pixels included in a predetermined image range; a specific pixel acquisition unit that acquires first pixel information related to an integrated value of a pixel included in the predetermined image range and in which a difference in the brightness of exposure from a pixel adjacent in a main scanning direction is equal to or more than a predetermined level, and second pixel information related to an integrated value of a pixel included in the predetermined image range as well and in which a difference in the brightness of exposure from a pixel adjacent in a sub-scanning direction is equal to or more than the predetermined level; a correction factor acquisition unit that acquires a correction factor of toner consumption corresponding to the brightness of exposure on the basis of the first pixel information and the second pixel information; and a consumption acquisition unit that corrects the toner consumption based on the brightness of exposure by using the correction factor acquired by the correction factor acquisition unit to acquire the toner consumption.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an image forming apparatus using an electrophotographic method.

Background Art

[0002] In an image forming apparatus employing an electrophotographic method, many configurations have been proposed that include toner remaining amount detecting means for detecting the remaining amount of toner (developer) in the toner storage section used for development and notifying the user. As a configuration of the toner remaining amount detecting means, in recent years, there has also been an increasing number of proposals to detect the toner remaining amount without using a physical toner remaining amount detecting means by counting the consumption amount of toner by counting the exposure pattern when forming an electrostatic latent image.

[0003] For example, Patent Document 1 discloses a method of counting a specific pixel among a plurality of pixels included in an image range as a horizontal edge or a vertical edge, and obtaining a correction amount of toner consumption based on information regarding the horizontal edge and the vertical edge.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, even if the number of counted pixels is the same, differences may occur in the actual toner consumption amount due to differences in the image content, such as character images, line images, halftone images, solid images, etc. To avoid this, there is a method of accumulating the consumption amount for each pixel, but there is a concern that the image processing will become complicated and enormous.

[0006] In addition, the method disclosed in Patent Document 1 suppresses the occurrence of a difference in consumption amount due to the ratio of vertical edges to the sum of horizontal edges and vertical edges, and it is difficult to say that it takes into account the number of pixels for a predetermined area, and it is not sufficient to consider the difference in image patterns.

[0007] An object of the present invention is to provide a technique that enables simple and highly accurate acquisition of toner consumption amount.

Means for Solving the Problems

[0008] To achieve the above object, an image forming apparatus of the present invention includes a photoreceptor, a charging unit that charges the photoreceptor, an exposure unit that exposes the surface of the photoreceptor charged by the charging unit based on image information to form an electrostatic latent image on the surface, a developing unit that develops the electrostatic latent image with toner to form a toner image on the surface, a transfer unit that transfers the toner image from the surface of the photoreceptor to a recording material, In an image forming apparatus comprising a pixel number acquisition unit that acquires the number of printed pixels in which the luminance of the exposure is equal to or greater than a predetermined value among the pixels included in a predetermined image range from the image information, a first pixel information using an integrated value of the number of pixels in which the luminance difference of the exposure with adjacent pixels in the main scanning direction included in a predetermined image range is equal to or greater than a predetermined magnitude, and an integrated value of the number of pixels in which the luminance difference with adjacent pixels in the sub-scanning direction included in a predetermined image range is equal to or greater than a predetermined magnitude a specific pixel acquisition unit that acquires second pixel information using, a correction rate acquisition unit that acquires a correction rate of toner consumption amount based on the luminance of the exposure based on the first pixel information and the second pixel information, a consumption amount acquisition unit that corrects and acquires the toner consumption amount based on the luminance of the exposure using the correction rate acquired by the correction rate acquisition unit, characterized by comprising.

Effects of the Invention

[0009] According to the present invention, it becomes possible to obtain the toner consumption amount simply and with high accuracy.

Brief Description of the Drawings

[0010]

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Modes for Carrying Out the Invention

[0011] Hereinafter, with reference to the drawings, embodiments for carrying out the present invention will be illustratively and in detail described based on examples. However, dimensions, materials, shapes, relative arrangements, etc. of the components described in this embodiment should be appropriately changed according to the configuration of the apparatus to which the invention is applied and various conditions. Also, not all combinations of features described in the embodiment are essential for the solution means of the invention. That is, the scope of the present invention is not intended to be limited to the following embodiments.

[0012] <Example 1> (Overall Configuration of Image Forming Apparatus) With reference to FIG. 2, the overall configuration of the image forming apparatus according to Example 1 of the present invention will be described. FIG. 2 is a schematic cross-sectional view of the image forming apparatus according to this example. Examples of the image forming apparatus to which the present invention is applied include image forming apparatuses that utilize an electrophotographic recording method such as a laser printer, a copier, and a facsimile.

[0013] The image forming apparatus A according to this example includes a photosensitive drum 1, a charging roller 2, an exposure device 3, a developing device 4, a transfer roller 5, and a fixing device 6. The charging roller 2 constitutes a charging device (charging unit) for charging the surface of the photosensitive drum 1 in the image forming apparatus A. The exposure device 3 is an exposure unit for exposing the surface of the charged photosensitive drum 1 based on exposure information corresponding to image data so as to form an electrostatic latent image corresponding to the image data (image information). The developing device 4 is a developing unit for developing the electrostatic latent image formed on the surface of the photosensitive drum 1 with toner (developer) T and forming a toner image on the surface of the photosensitive drum 1. The transfer roller 5 constitutes a transfer device (transfer unit) that sandwiches the recording material P between itself and the photosensitive drum 1 and transfers the toner image from the photosensitive drum 1 to the recording material P. The fixing device 6 is a fixing unit that heats and presses the recording material P to fix the toner image on the recording material P. Also, a power source (not shown) for applying a predetermined voltage to each of the charging roller 2, the developing device 4, the transfer roller 5, etc. is attached to the image forming apparatus A.

[0014] The photosensitive drum 1 is an image carrier on which an organic photosensitive member with negative charging property is formed on a cylindrical cylinder. Also, the photosensitive drum 1 has a diameter of φ24 mm and is rotationally driven by a motor in a predetermined direction (clockwise direction in the figure) at a predetermined process speed. The photosensitive drum 1 of this embodiment is rotationally driven at a process speed of 250 mm / sec.

[0015] The charging roller 2 is a charging means that is applied with a desired charging voltage by a power source (not shown), contacts the rotating photosensitive drum 1 with a predetermined pressure contact force, and uniformly charges the surface of the photosensitive drum 1 to a predetermined potential. In this embodiment, the photosensitive drum 1 is charged to a negative polarity by the charging roller 2. Also, the potential charged by the charging roller 2 is referred to as the dark part potential.

[0016] The exposure device 3 is an exposure means that performs exposure corresponding to image information input from an external device or a reading device. Examples of the exposure device 3 include a scanner unit that scans the surface of the photosensitive drum 1 with a semiconductor laser, and an LED exposure device having an LED array in which a plurality of LEDs are arranged along the longitudinal direction of the photosensitive drum 1. In this embodiment, as the exposure device 3, a scanner unit that performs scanning with a semiconductor laser is used. Also, the surface of the photosensitive drum 1 at the dark part potential is exposed by the exposure device 3, and the surface potential of the photosensitive drum 1 that has decayed near the ground potential is referred to as the bright part potential. That is, corresponding to the image information, by performing exposure with a predetermined amount of light, an image part formed at the bright part potential for positively attaching toner and a non-image part that is not exposed are formed on the photosensitive drum 1, thereby forming a so-called electrostatic latent image. Note that the non-image part may be formed to have a potential that does not positively attach toner by being exposed with a second amount of light that is less than the first amount of light when exposing the image part.

[0017] The developing device 4 is developing means including a developing roller 41 as a developer carrier for carrying a developer, a developing container serving as a frame of the developing device 4, a supply roller 42 capable of supplying the developer to the developing roller 41, and a developing blade 43 for regulating the amount of the developer. The developing roller 41 and the supply roller 42 are rotatably supported by the developing container. Further, the developing roller 41 is disposed at an opening of the developing container so as to face the photosensitive drum 1. The supply roller 42 is rotatably in contact with the developing roller 41, and toner as the developer stored in the developing container is applied onto the surface of the developing roller 41 by the supply roller 42. The developing blade 43 is an elastic member and is disposed in contact with the developing roller 41 while being elastically deflected against the developing roller 41. The toner carried on the surface of the developing roller 41 by the developing blade 43 has a predetermined layer thickness and is conveyed to a developing portion facing the photosensitive drum 1.

[0018] The developing device 4 of the present embodiment uses a contact developing method as a developing method. That is, the toner layer carried on the developing roller 41 carrying the toner contacts the photosensitive drum 1 in a developing portion (developing region) where the photosensitive drum 1 and the developing roller 41 face each other. A developing voltage is applied to the developing roller 41 by a power source (not shown). Under the developing voltage, the toner carried on the developing roller 41 is transferred from the developing roller 41 to the drum surface according to the potential of the surface of the photosensitive drum 1, so that the electrostatic latent image on the photosensitive drum is developed into a toner image.

[0019] As an example of the toner of the present embodiment, a polymer toner generated by a polymerization method, having a spherical particle size of 7 μm, and having a negative polarity as a normal charging polarity is used. Further, the toner of the present embodiment does not contain a magnetic component, and is a so-called non-magnetic one-component developer in which the toner is carried on the developing roller 41 mainly by intermolecular force and electrostatic force (image force). Further, in the one-component developer, in addition to the toner particles, additives (for example, waxes and silicas) for adjusting the fluidity and charging performance of the toner are also included. There may be cases where (fine particles). In addition, as the developer, a one-component magnetic developer containing a magnetic component or a two-component developer composed of a non-magnetic toner and a magnetic carrier may be used. When using a developer having magnetism, as the developer carrier, a cylindrical developing sleeve having a magnet disposed inside may be used in some cases.

[0020] The transfer roller 5 is a transfer means to which a transfer voltage is applied from a power source (not shown) and which transfers the toner image carried on the photosensitive drum 1 to the recording material P. The recording material P onto which the toner image has been transferred is conveyed to the fixing device 6.

[0021] The fixing device 6 is a heat fixing type fixing means for performing an image fixing process by heating and melting the toner on the recording material P. The fixing device 6 includes a fixing film, a fixing heater such as a ceramic heater for heating the fixing film, a thermistor for measuring the temperature of the fixing heater, and a pressure roller that presses against the fixing film. The recording material P that has passed through the fixing device 6 is discharged to the outside (outside the machine) of the image forming apparatus A by a pair of discharge rollers as discharge means and is stacked on a discharge tray as a stacking portion formed on the upper part of the printer main body.

[0022] On the other hand, the developer remaining on the photosensitive drum 1 without being transferred is removed from the photosensitive drum by a cleaning device 7 disposed on the downstream side of the transfer roller 5 with respect to the rotation direction of the photosensitive drum and is stored in the cleaning device 7. Although various configurations are conceivable for the cleaning device 7, here, a so-called cleaning blade configuration in which urethane rubber supported and fixed by sheet metal is brought into contact with the photosensitive drum in the counter direction with respect to the rotation direction of the photosensitive drum is used.

[0023] (Image signal generation unit, control unit, laser drive unit, calculation unit) FIG. 3 shows a block diagram of a control configuration related to image formation of the present image forming apparatus A. The breakdown thereof consists of an image signal processing unit 51, a control unit 52, a laser drive unit 53, and a calculation unit 54.

[0024] The image signal processing unit 51 receives print information from a host computer (not shown) and generates a VDO signal corresponding to the print information. The VDO signal is a signal for controlling the emission and extinction of the laser light of the semiconductor laser. The control unit 52 controls the image forming apparatus A and counts the presence or absence of pixels in the VDO signal. More specifically, the control unit 52 performs conversion from the VDO signal to a laser drive signal, conversion from the VDO signal to pixel count information, vertical edge count, and horizontal edge count. The laser drive unit 53 controls the emission and extinction of the laser light of the semiconductor laser based on the laser drive signal converted from the VDO signal, and forms a latent image on the scanned surface of the photosensitive drum 1 charged in advance.

[0025] The control unit 52 includes a pixel count unit 520 as a pixel number acquisition unit. The pixel count unit 520 acquires the number of pixels (printed pixels) among the pixels (pixels) included in a predetermined image range, for example, the range where an image can be formed on one recording material, for which the toner density to be attached becomes a predetermined value or more, from the VDO signal as image information.

[0026] Further, the control unit 52 includes a horizontal edge count unit 521 and a vertical edge count unit 522 as a specific pixel acquisition unit. In addition to the count of the presence or absence of pixels in the VDO signal by the pixel count unit 520, the control unit 52 performs the following processing by the horizontal edge count unit 521 and the vertical edge count unit 522.

[0027] That is, the horizontal edge count unit 521 counts that there is a horizontal edge for a certain pixel when the condition that there is a luminance difference of a certain level or more is satisfied among the pixels adjacent in the main scanning direction to the certain pixel. More specifically, the horizontal edge count unit 521 is for the pixels (printed pixels) whose exposure luminance becomes a predetermined value or more and the pixels adjacent in the main scanning direction Pixels with a difference in exposure luminance greater than or equal to a predetermined magnitude are counted as pixels with horizontal edges. Similarly, the vertical edge counter 522 counts a pixel as having a vertical edge when, for a certain pixel, there is a luminance difference of a certain magnitude or more among the pixels adjacent in the sub-scanning direction. More specifically, the vertical edge counter 522 counts, as pixels with vertical edges, pixels among the pixels (printed pixels) with an exposure luminance greater than or equal to a predetermined value, where the difference in exposure luminance between adjacent pixels in the sub-scanning direction is greater than or equal to a predetermined magnitude.

[0028] This operation will be described with reference to FIGS. 1(a) to 1(f). Note that the possible values of the pixels are 256 gradations from 0 to 255, and it is determined that there is an edge when the difference between adjacent luminance values is 240 or more.

[0029] In any of FIGS. 1(a) to 1(f), the pixel of interest is the pixel surrounded by a thick line.

[0030] In FIG. 1(a), since the luminance value of the pixel of interest is 255 and the pixels adjacent to it on the top, bottom, left, and right are also 255, the luminance difference between them is 0, and neither vertical nor horizontal edges are counted.

[0031] In FIG. 1(b), since the luminance value of the pixel of interest is 0 and the pixels adjacent to it on the top, bottom, left, and right are also 0, the luminance difference between them is 0, and neither vertical nor horizontal edges are counted. Note that pixels with a luminance value of 0 are not the target for counting pixels with edges in this embodiment, as will be described later.

[0032] In FIG. 1(c), since the luminance value of the pixel of interest is 255, the luminance value of the pixel adjacent above it is 0, and the bottom and left and right are 255, a vertical edge is counted and a horizontal edge is not counted.

[0033] In FIG. 1(d), since the luminance value of the pixel of interest is 255, the luminance value of the pixel adjacent on the left side is 0, and the upper, lower, and right values are 255, the vertical edge is not counted, and the horizontal edge is counted.

[0034] In FIG. 1(e), since the luminance value of the pixel of interest is 255, the luminance values of the pixels adjacent on the upper and lower sides are 0, and the left and right values are 255, the vertical edge is counted, and the horizontal edge is not counted. In FIG. 1(c), there was a luminance difference only above, but in FIG. 1(e), although there is a luminance difference both above and below, the same 1 is counted as the vertical edge count.

[0035] In FIG. 1(f), since the luminance value of the pixel of interest is 255, the luminance values of the pixels adjacent on the right and left sides are 255, and the upper and lower values are 0, the horizontal edge is counted, and the vertical edge is not counted. In FIG. 1(d), there was a luminance difference only on the left, but in FIG. 1(f), although there is a luminance difference both on the right and left, the same 1 is counted as the horizontal edge count.

[0036] In FIG. 1(g), since the luminance value of the pixel of interest is 255, the luminance value of the pixel adjacent on the upper and left sides is 0, and the luminance values of the pixels adjacent on the lower and right sides are 255, both the vertical edge and the horizontal edge are counted.

[0037] By repeating these, within a predetermined unit of the printed information (for example, one sheet of paper to be printed, etc.), the control unit 52 · The total count of VDO signals (hereinafter referred to as pixel count information) · The total count of horizontal edge counts (hereinafter referred to as horizontal edge count information) · The total count of vertical edge counts (hereinafter referred to as vertical edge count information) is calculated (acquired).

[0038] (Correction of toner consumption using edge count information) Here, a method for correcting the toner consumption using the previously calculated horizontal edge count information and vertical edge count information will be described.

[0039] As shown in FIG. 3, the calculation unit 54 includes a horizontal edge count rate calculation unit 541 and a vertical edge count rate calculation unit 542 that, together with the horizontal edge count unit 521 and the vertical edge count unit 522, constitute a specific pixel acquisition unit, and a correction rate calculation unit 543 as a correction rate acquisition unit. The calculation unit 54 receives pixel count information (the number of printed pixels), horizontal edge count information, and vertical edge count information from the control unit 52, performs predetermined calculation processing, and returns the calculated correction rate of the toner consumption amount to the control unit 52. Specifically, the horizontal edge count rate calculation unit 541 calculates and acquires the horizontal edge count rate as the first pixel information based on various information provided from the control unit 52. The horizontal edge count rate is the ratio of the number of pixels in which the difference in the exposure luminance from adjacent pixels in the main scanning direction included in a predetermined image range is equal to or greater than a predetermined magnitude, to the number of printed pixels in which the exposure luminance is equal to or greater than a predetermined value. Similarly, the vertical edge count rate calculation unit 542 calculates and acquires the vertical edge count rate as the second pixel information based on various information provided from the control unit 52. The vertical edge count rate is the ratio of the number of pixels in which the difference in the exposure luminance from adjacent pixels in the sub-scanning direction included in a predetermined image range is equal to or greater than a predetermined magnitude, to the number of printed pixels in which the exposure luminance is equal to or greater than a predetermined value. The correction rate calculation unit 543 calculates and acquires the correction rate of the toner consumption amount based on the horizontal edge count rate, the vertical edge count rate, and the like. The control unit 52 has a toner consumption amount calculation unit 523 as a consumption amount acquisition unit, and corrects and calculates the toner consumption amount based on the pixel count information that does not use the edge count rate by the correction rate provided from the correction rate calculation unit 543, and acquires it. The acquired toner consumption amount can be used, for example, to update the toner remaining amount information in the process cartridge in the image forming apparatus A. The updated toner remaining amount information can be used, for example, to notify the host computer of the toner remaining amount.

[0040] The horizontal edge count rate calculation unit 541 calculates the horizontal edge count rate = horizontal edge count information / pixel count information, and the vertical edge count rate calculation unit 542 calculates the vertical edge count rate = vertical edge count information / pixel count information. The horizontal edge count rate and the vertical edge count rate are defined as the ratio of pixels having a luminance difference of a certain level or more adjacent to each other in the horizontal or vertical direction with respect to the counted pixels, in other words, the ratio counted as horizontal edges or vertical edges. Here, the horizontal edge count rate and the vertical edge count rate are independently calculated parameters and are defined as parameters that simply represent what kind of image is the print information.

[0041] When both the horizontal edge count rate and the vertical edge count rate are large, it can be regarded as being composed of isolated one pixel or several pixels. Also, when the horizontal edge count rate is large but the vertical edge count rate is small, it can be regarded as being close to a so-called vertical line pattern. Conversely, when the vertical edge count rate is large and the horizontal edge count rate is small, it can be regarded as being close to a horizontal line pattern. Furthermore, when both the horizontal edge count rate and the vertical edge count rate are small, it can be seen that valid pixels are adjacent to each other, that is, it is in a state close to a solid image.

[0042] From the above description, it can be understood that even with the same pixel count, by using parameters such as the horizontal edge count rate and the vertical edge count rate in combination, in a predetermined printing range, information such as being close to an aggregate of isolated dots, being close to a line image, or being close to a solid image can be obtained.

[0043] Here, in an image forming apparatus that employs an electrophotographic method, it is obligatory to measure the consumption amount in a printing image and a printing mode defined in advance by a standard. For example, when calculating the consumption amount in the case of printing a predetermined printing image in a predetermined printing mode, the pixel count is normalized with 1, and it is considered and calculated what the consumption amount will be for various image patterns. Thus, it is possible to create a table regarding what the consumption amount will be when the edge count rate changes, in other words, what the correction rate will be.

[0044] Therefore, if the correction rate of the consumption amount can be determined according to the values of the vertical edge count rate and the horizontal edge count rate, it becomes possible to improve the accuracy of the consumption amount calculation by a relatively simple method for a simple pixel count.

[0045] The horizontal edge count rate and the vertical edge count rate used here are parameters calculated independently. As described above, prepare a table such as Table 1 in Fig. 10(a) corresponding to isolated dots, line images, and solid images. The table of Table 1 defines the correction rate of the toner consumption amount determined according to the correspondence between the horizontal edge count rate as the first pixel information and the vertical edge count rate as the second pixel information.

[0046] As can be understood from the explanations so far, the calculation method of the correction amount in this embodiment does not calculate the consumption amount per pixel. The method of this embodiment is characterized in that, for the pixel count obtained from the print information in a certain range, the horizontal edge count rate and the vertical edge count rate are obtained, and the table of Table 1 in Fig. 10(a) corresponding to each value is used to calculate the correction amount for the pixel count.

[0047] The present invention realizes a toner consumption measurement method using pixel counting, which enables correspondence to various image patterns by a relatively simple method without requiring complicated processing even as high speed and high definition progress. According to the present invention, by using a horizontal edge count and a vertical edge count, which are relatively easily calculable and independent parameters from each other, it is possible to easily determine whether pixels are discretely arranged or collectively arranged. As a result, it becomes possible to derive an appropriate correction rate for changes in consumption due to differences in printing patterns, and it becomes possible to improve the accuracy of consumption calculation using pixel counting.

[0048] (Actual application example) Regarding specific application examples of embodiments of the present invention, as a simplified example, two exemplary patterns shown in FIGS. 4 and 5, which are 15 pixels × 36 pixels = 540 pixels and are binary images, will be described.

[0049] In the description here, pixels indicated by blanks are shown in white, and pixels indicated as printed portions are shown in black. For the sake of explanation, the pixels indicated as printed portions are shown in a numbered form to refer to each pixel.

[0050] The pattern shown in FIG. 4 has 138 pixels as pixel count information counted as printed portions. On the other hand, from the pattern of FIG. 4, the pixels with both vertical and horizontal edges are 1, 12, 25, 36, 37, 41, 46, 47, 51, 55, 58 to 66, 68, 69, 71 to 73, 76, (partially omitted in the middle), 125, 131, 132, 138, a total of 43 pixels. Similarly, the pixels with only vertical edges are a total of 39 pixels including 2 to 11, 26 to 35, etc., and the pixels with only horizontal edges are a total of 21 pixels including 13, 24, etc. Therefore, in the pattern shown in FIG. 4, the vertical edge count, which is the integrated value of pixels with vertical edges, is 82 obtained by adding 43 and 39, and the horizontal edge count, which is the integrated value of pixels with horizontal edges, is 64 obtained by adding 43 and 21. Therefore, the vertical edge count rate is 8 The vertical edge count rate is 2 / 138 = 59.4%, and the horizontal edge count rate is 64 / 138 = 46.3%. The correction rate corresponding to the vertical edge count rate of 59.4% and the horizontal edge count rate of 46.3% is 0.9 by using Table 1 in Fig. 10(a).

[0051] In the case of the pattern shown in Fig. 5, the pixel count information counted as the printing part is 402 pixels. Similar to the pattern shown in Fig. 4, there are 26 pixels with both vertical and horizontal edges, 78 pixels with only vertical edges, and 107 pixels with only horizontal edges. Similarly, the vertical edge count of the pattern shown in Fig. 5 is 104, and the horizontal edge count is 133. Therefore, the vertical edge count rate is 104 / 402 = 25.9%, and the horizontal edge count rate is 133 / 402 = 33.1%. From Table 1 in Fig. 10(a), the correction rate is 1.2. The above results are summarized in Table 2 in Fig. 10(b).

[0052] Although the concept was shown in a 540-pixel image in this example, in reality, when it is a binary image of letter size at 600 dpi, it becomes an image such as 4000 pixels × 6000 pixels. Therefore, in the method of performing processing according to the pattern of the luminance difference between adjacent pixels for each pixel and accumulating the consumption amount for each pixel, the processing becomes complicated, and it becomes difficult to correct the toner consumption amount in real time. In other words, it is expected that it will be difficult to quickly calculate the toner consumption amount and provide the remaining amount information.

[0053] On the contrary, if the method as in this embodiment is used, for the target pixel, it is only necessary to count whether there are vertical or horizontal edges, and use the accumulated value as the edge count information. It can be seen that the accuracy can be improved far more than the simple accumulated value of pixel counts.

[0054] In the descriptions so far, examples have been shown that are applied to binary images determined by two gradations of 0 and 1. However, the present invention can be similarly applied even in the case of multi-valued images having 256 gradations from 0 to 255. As an example, when there is a luminance difference of a certain level or more (more specifically, an example where the luminance difference is 240 or more), it can be considered to count as a vertical edge or a horizontal edge when it exists for pixels above or below, right or left. Even in this case, since it is possible to effectively correct the consumption amount for the multi-valued image by the edge count rate in a manner similar to the previous description, it is also effective in the multi-valued image.

[0055] Also, in this example, correction is performed using the vertical edge count rate and the horizontal edge count rate as the first pixel information and the second pixel information. However, a correction table similar to Table 1 in Fig. 10(a) may be prepared using the vertical edge count and the horizontal edge count themselves. As an example, it is shown in Table 3 of Fig. 11.

[0056] As long as the configuration is such that pixel counting is always performed within a fixed printed image range, even without normalizing in the form of an edge count rate as in Table 1 of Fig. 10(a), it is possible to correct the consumption amount in the same way using the absolute values of the horizontal edge count and the vertical edge count.

[0057] In the examples shown so far, when α≠β, the same correction table was prepared for the case where the vertical edge and the horizontal edge are α and β, and the case where the vertical edge and the horizontal edge are β and α. However, a correction table with different weightings may be prepared. When considering factors such as crowding, it is also possible to increase the consumption amount correction for the vertical edge.

[0058] Furthermore, instead of fixing the correction table in Table 1 of Fig. 10(a), a plurality of these tables may be prepared according to the environment in which the image forming apparatus is installed. Alternatively, the correction table may be switched when toner is replenished. That is, various variations can be considered not limited to the examples shown in this example.

[0059] As shown above, it has been shown that an appropriate correction process regarding the consumption amount using pixel count can be realized by a relatively simple method of determining whether or not the pixel of interest has an edge.

[0060] <Example 2> The image forming apparatus according to Example 2 of the present invention will be described. In Example 2, the same components as those in Example 1 are denoted by the same reference numerals and the description thereof is omitted. Matters not particularly described herein in Example 2 are the same as those in Example 1.

[0061] In Example 1, when either the upper or lower direction was blank, the vertical edge was counted, and when either the left or right direction was blank, the horizontal edge was counted. On the other hand, in Example 2, a major difference from Example 1 is that the cases of only the upper or lower side and the cases of both the upper and lower sides are distinguished.

[0062] The counting of the vertical and horizontal edges in this example will be described with reference to FIGS. 6(a) to 6(h) in a form compared with FIG. 1 used for the description in Example 1.

[0063] In any of FIGS. 6(a) to 6(h), the pixel of interest is the pixel surrounded by a thick line.

[0064] In FIG. 6(a), since the luminance value of the pixel of interest is 255 and the pixels adjacent to it in the vertical and horizontal directions are also 255, the luminance difference between them is 0, and neither the vertical edge nor the horizontal edge is counted.

[0065] In FIG. 6(b), since the luminance value of the pixel of interest is 0 and the pixels adjacent to it in the vertical and horizontal directions are also 0, the luminance difference between them is 0, and neither the vertical edge nor the horizontal edge is counted. Note that the pixel with a luminance value of 0 is not the target for counting pixels with an edge also in this example.

[0066] In Fig. 6(c), since the luminance value of the pixel of interest is 255, the luminance value of the pixel adjacent above it is 0, and the luminance values of the pixels below and on the left and right are 255, vertical edges are counted and horizontal edges are not counted.

[0067] In Fig. 6(d), since the luminance value of the pixel of interest is 255, the luminance value of the pixel adjacent to its left is 0, and the luminance values of the pixels above, below, and to the right are 255, vertical edges are not counted and horizontal edges are counted.

[0068] In Fig. 6(e), since the luminance value of the pixel of interest is 255, the luminance values of the pixels adjacent above and below it are 0, and the luminance values of the pixels on the left and right are 255, vertical edges are counted twice (above and below), and horizontal edges are not counted.

[0069] In Fig. 6(f), since the luminance value of the pixel of interest is 255, the luminance values of the pixels adjacent to its right and left are 255, and the luminance values of the pixels above and below are 0, horizontal edges are counted twice (left and right), and vertical edges are not counted.

[0070] In Fig. 6(g), since the luminance value of the pixel of interest is 255, the luminance value of the pixel adjacent above and to the left is 0, and the luminance values of the pixels adjacent below and to the right are 255, both vertical and horizontal edges are counted once.

[0071] In Fig. 6(h), since the luminance value of the pixel of interest is 255, and the luminance values of the pixels adjacent above, below, to the right, and to the left are all 0, both horizontal and vertical edges are counted twice. respectively, so both horizontal and vertical edges are counted twice.

[0072] In this embodiment, for one pixel, the vertical edges can be the top and the bottom, and the horizontal edges can be the left and the right. Therefore, when it becomes an edge on both sides, that is, when both the top and the bottom, and the left and the right are counted as edges, the counted number is doubled and the edge count is set to 2. On the other hand, when only one side becomes an edge, that is, only the top or only the bottom, or only the left or only the right, the edge count is set to 1. By adding weighting or changing the content of the weighting according to the content of the edge in this way, it is assumed that it becomes easier to discriminate a pattern closer to an isolated pixel.

[0073] Therefore, for the effective pixel count, the vertical edge count rate = vertical edge count / (2 × number of pixel counts), and the horizontal edge count rate = horizontal edge count / (2 × number of pixel counts). As the count rate, the edge count rate may be applied in the range of 1 to 100% as shown in Table 1 of Fig. 10(a).

[0074] Items such as the configuration of the image forming apparatus itself, the image signal generation unit, the control unit, the laser driving unit, and the calculation unit, which are common to Embodiment 1, are omitted here.

[0075] Here, the effects in this embodiment are also explained by comparing with Embodiment 1 using some 540-pixel binary images. The explanation is given using three patterns of images in Figs. 7, 8, and 9 such that the pixel counts are the same (96 pixels) respectively.

[0076] Fig. 7 shows a case where there are four printing parts of 2 pixels × 12 pixels. When Embodiment 1 is applied, the vertical edge count is 96 and the horizontal edge count is 16. Also in Embodiment 2, the vertical edge count is 96 and the horizontal edge count is 16.

[0077] Fig. 8 shows a case where there are 24 printing parts of 2 pixels × 2 pixels. When Embodiment 1 is applied, the vertical edge count is 96 and the horizontal edge count is 96. Also in Embodiment 2, the vertical edge count is 96 and the horizontal edge count is 96.

[0078] FIG. 9 has 96 printing portions of 1 pixel × 1 pixel. When Example 1 is applied, the vertical edge count is 96 and the horizontal edge count is 96. Even in Example 2, the vertical edge count is 192 and the horizontal edge count is 192.

[0079] When calculating the edge count rate respectively, it becomes as shown in Table 4 of FIG. 12(a).

[0080] Even in Example 2, it is possible to use the table of Table 1 in FIG. 10(a). However, in the printed image of FIG. 8, in the case of Example 1, since both the vertical edge count rate and the horizontal edge count rate are 100%, the correction rate is 0.5.

[0081] On the other hand, in the case of Example 2, since the vertical edge count rate and the horizontal edge count rate are 50%, the correction rate becomes 1. Then, in the case of small pixels that form a shallow electrostatic latent image pattern, it may not be possible to reflect the actual situation where the toner consumption is small, which is not preferable.

[0082] Therefore, in this embodiment, as an example, a table different from Table 1 in FIG. 10(a) is prepared as Table 5 in FIG. 12(b). This is a form considering that in one pixel, there may be a maximum of 2 edges in both the vertical and horizontal directions. That is, for one pixel, the vertical edge and the horizontal edge can each be 0, 1, or 2, so that for the count of valid pixels, twice that is the maximum vertical edge and horizontal edge.

[0083] In the edge count in Example 1, in both FIGS. 6(c) and 6(e), the vertical edge count is 1, and in both FIGS. 6(d) and 6(f), the horizontal edge count is 1. On the other hand, in the edge count of this embodiment, the vertical edge count in FIG. 6(e) is 2, and the horizontal edge count in FIG. 6(f) is 2.

[0084] In FIGS. 7, 8, and 9, for each pattern, when the table 1 in FIG. 10(a) of Example 1 is applied and when the table 5 in FIG. 12(b) of Example 2 is applied, the correction rates are shown in Table 6 of FIG. 13.

[0085] In Example 1, for the pattern in FIG. 8 and the pattern in FIG. 9, the same edge count is obtained, so the same correction rate is obtained. In contrast, in this example, since the edge counts are different values, different correction rates can be set for the pattern in FIG. 8 and the pattern in FIG. 9.

[0086] For the edge count rate as in Table 5 of FIG. 12(b), in the case of an image with a low printing rate such as many isolated dots, the table evenly allocated has the advantage that it can be more finely classified compared to Table 1 in FIG. 10(a). However, when there are many high-printing images such as solid images, there is a possibility that the classification becomes coarser compared to Table 1 in FIG. 10(a).

[0087] In order to achieve both, a corrected table can be considered, which is deformed so that the portion of 1 to 50% of the edge count rate in Table 5 of FIG. 12(b) is made finer, and the correction rate is the same as that of Table 1 in FIG. 10(a) even in the case of an image with a relatively high printing rate.

[0088] Table 7 in FIG. 14 is obtained by classifying the portion of 1 to 50% of the edge count rate in Table 5 of FIG. 12(b) into 10 steps instead of 5 steps. Similarly, in this example, when the table in Table 7 of FIG. 14 is used instead of the table in Table 5 of FIG. 12(b), the result is as shown in Table 8 of FIG. 15.

[0089] From the above, it is shown that by setting an appropriate correction table even in the case of considering edges independently for up / down and left / right for each pixel, it becomes possible to correct the consumption amount based on the pixel count.

[0090] The above embodiments can be combined with each other in terms of their respective configurations.

[0091] The disclosure of the embodiments of the present invention includes the following configurations. (Configuration 1) A photoreceptor, A charging unit that charges the photoreceptor, An exposure unit that exposes the surface of the photoreceptor charged by the charging unit based on image information to form an electrostatic latent image on the surface, A developing unit that develops the electrostatic latent image with toner to form a toner image on the surface, A transfer unit that transfers the toner image from the surface of the photoreceptor to a recording material, In an image forming apparatus comprising: A pixel number acquisition unit that acquires the number of printed pixels in which the luminance of the exposure is equal to or greater than a predetermined value among the pixels included in a predetermined image range from the image information, First pixel information using an integrated value of the number of pixels in which the difference in the luminance of the exposure between adjacent pixels in the main scanning direction included in a predetermined image range is equal to or greater than a predetermined magnitude, and Second pixel information using an integrated value of the number of pixels in which the difference in the luminance between adjacent pixels in the sub-scanning direction included in a predetermined image range is equal to or greater than a predetermined magnitude, and a specific pixel acquisition unit that acquires the second pixel information, A correction rate acquisition unit that acquires a correction rate of the toner consumption amount based on the luminance of the exposure based on the first pixel information and the second pixel information, A consumption amount acquisition unit that corrects and acquires the toner consumption amount based on the luminance of the exposure using the correction rate acquired by the correction rate acquisition unit, An image forming apparatus characterized by comprising the above. (Configuration 2) The first pixel information is a ratio of the number of pixels in which the difference in the luminance of the exposure between adjacent pixels in the main scanning direction included in a predetermined image range is equal to or greater than a predetermined magnitude to the number of printed pixels in which the luminance of the exposure acquired by the pixel number acquisition unit is equal to or greater than a predetermined value, The second pixel information is a ratio of the number of pixels in which the difference in the luminance of the exposure between adjacent pixels in the sub-scanning direction included in a predetermined image range is equal to or greater than a predetermined magnitude to the number of printed pixels in which the luminance of the exposure acquired by the pixel number acquisition unit is equal to or greater than a predetermined value. The image forming apparatus according to Configuration 1, characterized in that. (Configuration 3) The first pixel information is the number of pixels in a predetermined image range where the luminance difference in exposure between adjacent pixels in the main scanning direction is equal to or greater than a predetermined magnitude, The second pixel information is the number of pixels in a predetermined image range where the luminance difference in exposure between adjacent pixels in the sub-scanning direction is equal to or greater than a predetermined magnitude, according to the image forming apparatus according to Configuration 1. (Configuration 4) The correction rate obtained by the correction rate acquisition unit is preset according to the correspondence between the first pixel information and the second pixel information, according to the image forming apparatus according to any one of Configurations 1 to 3. (Configuration 5) For the number of pixels where the luminance difference is equal to or greater than a predetermined magnitude only between pixels on one side in the main scanning direction in the first pixel information, a weight is added to the number of pixels where the luminance difference is equal to or greater than a predetermined magnitude between pixels on both sides in the main scanning direction, and then it is counted, The second pixel information is counted by adding a weight to the number of pixels where the luminance difference is equal to or greater than a predetermined magnitude only between pixels on one side in the sub-scanning direction, with respect to the number of pixels where the luminance difference is equal to or greater than a predetermined magnitude between pixels on both sides in the sub-scanning direction, according to the image forming apparatus according to any one of Configurations 1 to 4. (Configuration 6) The weighting is to count by doubling the number, according to the image forming apparatus according to Configuration 5.

Explanation of Signs

[0092] 1... Photoconductor, 2... Charging roller, 3... Exposure device, 4... Developing device, 5... Transfer roller, 51... Image signal processing unit, 52... Control unit, 53... Laser driving unit, 54... Calculation unit

Claims

1. A photoreceptor, a charging unit that charges the photoreceptor, an exposure unit that exposes the surface of the photoreceptor charged by the charging unit based on image information to form an electrostatic latent image on the surface, a developing unit that develops the electrostatic latent image with toner to form a toner image on the surface, a transfer unit that transfers the toner image from the surface of the photoreceptor to a recording material, In an image forming apparatus comprising: a pixel number acquisition unit that acquires the number of printed pixels in which the luminance of the exposure is equal to or greater than a predetermined value among the pixels included in a predetermined image range from the image information; a specific pixel acquisition unit that acquires first pixel information using an integrated value of the number of pixels in which the difference in the luminance of the exposure between adjacent pixels in the main scanning direction included in a predetermined image range is equal to or greater than a predetermined magnitude, and second pixel information using an integrated value of the number of pixels in which the difference in the luminance of the exposure between adjacent pixels in the sub-scanning direction included in a predetermined image range is equal to or greater than a predetermined magnitude; a correction rate acquisition unit that acquires a correction rate of toner consumption based on the luminance of the exposure based on the first pixel information and the second pixel information; a consumption amount acquisition unit that corrects and acquires the toner consumption based on the luminance of the exposure using the correction rate acquired by the correction rate acquisition unit; An image forming apparatus characterized by comprising the above.

2. The first pixel information is a ratio of the number of pixels in which the difference in the luminance of the exposure between adjacent pixels in the main scanning direction included in a predetermined image range is equal to or greater than a predetermined magnitude to the number of printed pixels in which the luminance of the exposure acquired by the pixel number acquisition unit is equal to or greater than a predetermined value, The second pixel information is a ratio of the number of pixels in which the difference in the luminance of the exposure between adjacent pixels in the sub-scanning direction included in a predetermined image range is equal to or greater than a predetermined magnitude to the number of printed pixels in which the luminance of the exposure acquired by the pixel number acquisition unit is equal to or greater than a predetermined value. The image forming apparatus according to claim 1.

3. The first pixel information is the number of pixels in which the difference in the luminance of the exposure between adjacent pixels in the main scanning direction included in a predetermined image range is equal to or greater than a predetermined magnitude, The second pixel information is the number of pixels in which the difference in the luminance of the exposure between adjacent pixels in the sub-scanning direction included in a predetermined image range is equal to or greater than a predetermined magnitude. The image forming apparatus according to claim 1.

4. The correction rate acquired by the correction rate acquisition unit is preset according to the correspondence relationship between the first pixel information and the second pixel information. The image forming apparatus according to any one of claims 1 to 3.

5. The first pixel information is counted by adding a weight to the number of pixels in which the luminance difference is equal to or greater than a predetermined magnitude only between pixels on one side in the main scanning direction, with respect to the number of pixels in which the luminance difference is equal to or greater than a predetermined magnitude between pixels on both sides in the main scanning direction. The second pixel information is counted by adding a weight to the number of pixels in which the luminance difference is equal to or greater than a predetermined magnitude only between pixels on one side in the sub-scanning direction, with respect to the number of pixels in which the luminance difference is equal to or greater than a predetermined magnitude between pixels on both sides in the sub-scanning direction. The image forming apparatus according to any one of claims 1 to 3, characterized in that.

6. The image forming apparatus according to claim 5, characterized in that the weighting is to count by doubling the number.

Images