JP4627180B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to a toner formed by forming an electrostatic latent image on the surface of a photosensitive drum rotatably supported, and attaching two or more predetermined number of different color toners to the formed electrostatic latent image. The present invention relates to an image forming apparatus that forms a color image by transferring an image onto a transfer material.

  In an image forming apparatus such as a color printer or a color copying machine that prints characters, images or the like on a transfer material such as recording paper in a predetermined number of two or more different colors, the change in the environment in which the apparatus is disposed, It is known that print output characteristics such as density characteristics change due to a change in state or the like. For example, when the temperature, humidity, etc. of the atmosphere in which the color copying machine is placed change, the amount of toner adhering to the recording paper changes, and the output characteristics may not be desired. Further, when printing is performed continuously for a long time, the temperature of each part of the apparatus rises, and the output characteristics may change accordingly.

In order to compensate for such a change in output characteristics, adjustment of the output characteristics (hereinafter referred to as calibration) is performed. As calibration, for example, a patch is formed on an intermediate transfer member, the density is read, and the developing bias value of the developing device is adjusted based on the result (see Patent Document 1).
JP 2002-229278 A

  However, when the above calibration is performed, toner is consumed to form a patch, and particularly when calibration is performed for each toner color, a long work time is required for the calibration. There was.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to reduce toner consumption and work time for calibration.

The image forming apparatus according to claim 1 forms an electrostatic latent image on a surface of a photosensitive drum rotatably supported, and two or more predetermined numbers of different color toners are formed on the formed electrostatic latent image. An image forming apparatus that forms a color image by transferring a toner image that has been attached to a transfer material, and generates a toner image on the photosensitive drum for each of the predetermined number of toners. A developing unit, a density adjusting unit that adjusts the density of each color toner image generated by the predetermined number of developing units, and the predetermined number of times to the density adjusting unit at a predetermined density adjusting timing. The adjustment instruction means for giving an instruction to adjust the density of each color toner image generated by the developing means, and the previous density adjustment timing and the current density adjustment timing for each of the predetermined number of toners. door between Comprising a consumption detecting means for determining the consumption of over, and a judgment means for judging whether the consumption is less than a predetermined value, said adjustment instruction means, the consumption by the determining means For the developing unit corresponding to the toner determined to be less than or equal to the predetermined value, the density adjusting unit is instructed to skip the adjustment at the current density adjustment timing.

  According to the above configuration, the predetermined number of developing units corresponding to the number of colors of toner generates a toner image on the photosensitive drum for each predetermined number of toners, and the density adjusting unit performs the predetermined number of developing units. The density of each color toner image to be generated is adjusted. Then, the adjustment instruction unit instructs the density adjustment unit to adjust the density of the toner images of the respective colors generated by the predetermined number of developing units at a predetermined density adjustment timing.

The consumption amount detecting means obtains the toner consumption amount between the previous density adjustment timing and the current density adjustment timing for each predetermined number of toners, and the determination means presets the toner consumption amount. It is determined whether the value is equal to or less than the predetermined value. Further, the density adjustment unit is instructed by the adjustment instruction unit to skip the adjustment at the current density adjustment timing for the developing unit corresponding to the toner whose toner consumption is determined to be equal to or less than the predetermined value by the determination unit. The

  Therefore, the adjustment at the current density adjustment timing is skipped for the developing means corresponding to the toner whose toner consumption is determined to be less than or equal to the predetermined value (that is, the developing means having a relatively low density adjustment necessity). Therefore, toner consumption and working time are reduced.

  According to a second aspect of the present invention, the image forming apparatus includes a timing setting unit that receives an operation input from the outside and sets the density adjustment timing.

  According to the above configuration, the density adjustment timing is set by receiving the input from the outside by the timing setting means, so that the density adjustment timing desired by the operator or the like can be set.

  The image forming apparatus according to claim 3 is characterized in that the timing setting unit sets, as a density adjustment timing, a timing at which the cumulative number of transfer materials on which an image has been formed is increased by a predetermined number.

  According to the configuration described above, the timing at which the cumulative number of transfer materials on which an image has been formed is set as the density adjustment timing by the timing setting means, so that an appropriate density adjustment timing is set.

  5. The image forming apparatus according to claim 4, wherein each time an image is formed, a dot count unit that counts and accumulates the number of dots of each color of toner included in the image data, and a dot count unit for each density adjustment timing. Dot number storage means for storing the dot count value of each color according to the above, wherein the consumption amount detection means is based on the dot count value at the previous density adjustment timing and the dot count value at the current density adjustment timing. It is characterized by calculating.

According to the above configuration, every time an image is formed by the dot count unit, the number of dots of each color of toner included in the image data is counted and integrated, and the dot number storage unit stores the dot for each density adjustment timing. The dot count value of each color by the counting means is stored. The consumption amount detecting means calculates the toner consumption amount based on the dot count value at the previous density adjustment timing and the dot count value at the current density adjustment timing.

  Accordingly, since the toner consumption is calculated based on the dot count values at the previous and current density adjustment timings, the toner consumption is easily and accurately calculated. For example, by subtracting the dot count value of the previous density adjustment timing from the dot count value of the current density adjustment timing, and multiplying the result by a predetermined value (average value of toner consumption per dot), The amount of toner consumption can be calculated easily and accurately.

  The image forming apparatus according to claim 5, wherein a replenishing unit that replenishes the developing unit with toner from a toner container that stores toner of each color, and a replenishment amount for determining a replenishing amount of toner to the developing unit by the replenishing unit. And a consumption means for calculating the consumption amount based on a toner supply amount by the supply means from a previous density adjustment timing to a current density adjustment timing. .

  According to the above configuration, the replenishing unit replenishes toner to the developing unit from the toner container that stores toner of each color, and the replenishing amount calculating unit obtains the replenishing amount of toner to the developing unit by the replenishing unit. The consumption amount detection means calculates the toner consumption amount based on the toner supply amount by the supply means from the previous density adjustment timing to the current density adjustment timing.

  Accordingly, since the toner consumption amount is calculated based on the toner replenishment amount from the previous density adjustment timing to the current density adjustment timing, the toner consumption amount is easily calculated.

  The image forming apparatus according to claim 6, a color determination unit that determines whether or not each color of toner is included in the image data every time an image is formed, and a determination that each color of toner is included in the image data. A sheet number counting means for counting the number of sheets formed by adding up the number of image formations, and a sheet number storing means for storing the count value of the number of each toner color. The consumption amount is calculated based on the count value of the number of sheets and the count value of the number of sheets at the current density adjustment timing.

  According to the above configuration, each time an image is formed by the color determination unit, it is determined whether or not each color of toner is included in the image data, and each color of toner is included in the image data by the number counting unit. When the determination is made, the number of image formations is integrated and the number of sheets is counted. Then, the count value of the number of sheets for each color of toner is stored in the number-of-sheets storage means. Further, the consumption amount detecting means calculates the toner consumption amount based on the count value of the number of sheets at the previous density adjustment timing and the count value of the number of sheets at the current density adjustment timing.

  Therefore, since the toner consumption is calculated based on the count value of the number of sheets at the previous density adjustment timing and the count value of the number of sheets at the current density adjustment timing, the toner consumption is calculated more easily.

  The image forming apparatus according to claim 7 is a tandem type color image forming apparatus in which the predetermined number of photosensitive drums are arranged.

  According to the above configuration, since the tandem type color image forming apparatus is provided with a predetermined number of photosensitive drums, toner consumption and working time are significantly reduced.

  According to the first aspect of the present invention, the developing means corresponding to the toner whose toner consumption is determined to be equal to or less than the predetermined value (that is, the developing means having a relatively low density adjustment necessity) Since adjustment at the density adjustment timing is skipped, toner consumption and work time can be reduced.

  According to the second aspect of the present invention, the density adjustment timing is set by accepting the input from the outside, so that the density adjustment timing desired by the operator or the like can be set.

  According to the third aspect of the present invention, the timing at which the cumulative number of transfer materials on which an image is formed is increased by a predetermined number is set as the density adjustment timing, so that an appropriate density adjustment timing can be set.

  According to the fourth aspect of the invention, since the toner consumption is calculated based on the dot count values at the previous and current density adjustment timings, the toner consumption can be calculated easily and accurately. .

  According to the fifth aspect of the present invention, since the toner consumption amount is calculated based on the toner replenishment amount from the previous density adjustment timing to the current density adjustment timing, the toner consumption amount can be easily calculated. The consumption can be calculated.

  According to the sixth aspect of the present invention, the toner consumption amount is calculated based on the count value of the number of sheets at the previous density adjustment timing and the count value of the number of sheets at the current density adjustment timing. Can be calculated.

  According to the seventh aspect of the present invention, since it is a tandem color image forming apparatus in which a predetermined number of photosensitive drums are arranged, it is possible to remarkably reduce toner consumption and working time.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram illustrating an example of a configuration of an image forming apparatus according to an embodiment of the present invention. The image forming apparatus is a tandem type color printer 1, which includes a paper feed cassette 10, a transfer transport unit 20 disposed above the paper feed cassette, and an image disposed above the transfer transport unit 20. The forming unit 30, the fixing unit 40 disposed on the left side of the transfer conveyance unit 20, the first conveyance path 50 that guides the recording paper P set in the paper feed cassette 10 to the transfer conveyance unit 20, and the fixing unit 40. And a second transport path 60 that guides the recording paper P on which the fixing process has been performed to the discharge tray 80.

  The paper feed cassette 10 has recording paper P stacked therein, picks up the stacked recording paper P one by one by a paper feed roller (not shown), and discharges it to the first transport path 50 side. The image forming unit 30 includes image forming units 30K, 30Y, 30M, and 30C that form toner images of black (K), yellow (Y), magenta (M), and cyan (C), respectively. . Since the image forming units 30K to 30C have the same configuration, the image forming unit 30K will be described below, and the description of the configuration of the image forming units 30Y, 30M, and 30C will be omitted.

  The image forming unit 30K includes a photosensitive drum 31K, a charging unit 32K, an exposure unit 33K, a developing unit 34K, and a cleaner unit 35K. The photosensitive drum 31K is a cylindrical member, and rotates in the clockwise direction (the direction of arrow A in the drawing) in response to a driving force from a motor (not shown). The exposure unit 33K includes a light source such as a laser diode. The exposure unit 33K irradiates the surface of the photosensitive drum 31K substantially uniformly charged by the charging unit 32K with an optical signal corresponding to the image data, thereby electrostatically charging the image data. It forms a latent image.

  The developing unit 34K includes a toner container 341K that stores black (K) toner, and supplies black (K) toner to the surface of the photosensitive drum 31K on which the electrostatic latent image is formed. A toner image is formed. A black (K) toner image formed on the photosensitive drum 31 is transferred to the recording paper P or the transfer belt 21 by a transfer roller 22K described later. The cleaner 35K removes the toner adhering to the surface of the photosensitive drum 31K to which the black (K) toner image is transferred.

  The transfer conveyance unit 20 includes a transfer belt 21, a transfer roller 22 (transfer rollers 22K, 22Y, 22M, and 22C are collectively referred to as transfer roller 22), a right roller 23, and a left roller 24. The right roller 23 is disposed below the image forming unit 30K, and the left roller 24 is disposed below the image forming unit 30C and is configured to be rotatable.

  The transfer belt 21 is an endless belt stretched between the right roller 23 and the left roller 24, and is rotated in the counterclockwise direction (the direction of arrow B in the figure) by the right roller 23 and the left roller 24. It is rotated at a predetermined speed. The transfer belt 21 is made of a heat-resistant resin material (for example, polyimide resin). Four transfer rollers 22K to 22C are arranged on the inner peripheral side of the transfer belt 21 and at positions facing the four photosensitive drums 31K to 31C. The transfer rollers 22 </ b> K to 22 </ b> C are made of a conductive rubber material or the like, and transfer the color toner images formed on the photosensitive drums 31 </ b> K to 31 </ b> C onto the recording paper P or the transfer belt 21.

  Two density sensors 70 are arranged in parallel in the width direction of the transfer belt 21 (perpendicular to the paper surface) on the outer peripheral side of the transfer belt 21 and in the vicinity of the left roller 24. The density sensor 70 is composed of, for example, a reflection type photosensor, and measures the density of the toner image formed on the transfer belt 21.

  The fixing unit 40 includes a heat shielding box 41, a fixing roller 42 with a built-in heater, and a pressure roller 43. The fixing unit 40 heats and conveys the recording paper P on which the toner image is formed, whereby the toner image is formed on the recording paper P. It is to fix.

  FIG. 2 is a block diagram illustrating an example of a functional configuration of the color printer 1 illustrated in FIG. The color printer 1 includes a scanner unit 300 that generates image data, an image memory 400 that stores image data, the density sensor 70 described above, a printing unit 200 that prints image data on recording paper P, and the color printer 1. And a control unit 100 that controls the operation.

  The scanner unit 300 reads an image of a document with a photoelectric conversion element such as a CCD, and outputs the obtained document image data to the control unit 100. The printing unit 200 includes the transfer conveyance unit 20, the image forming unit 30, and the fixing unit 40 illustrated in FIG. 1, reads out image data stored in the image memory 400 under the control of the control unit 100, and records paper P is to be printed. The image memory 400 stores image data of a document read by the scanner unit 300 under the control of the control unit 100.

  The control unit 100 counts the number of dots of each color (black (B), yellow (Y), magenta (M), and cyan (C)) of toner included in the image data, and counts TK, TY, TM, A dot count unit 101 (corresponding to dot count means) for obtaining TC, a dot number storage unit 102 (corresponding to dot number storage means) for storing count values TK, TY, TM, and TC of each color, and toner of each color Consumption amount detecting unit 103 (corresponding to consumption amount detecting means) for obtaining consumption amounts ΔTK, ΔTY, ΔTM, and ΔTC of toner, and toner consumption amounts ΔTK, ΔTY, ΔTM, and ΔTC of each color are set to predetermined values ΔTS1 to ΔT1. Instructions for adjusting the density of each color toner image to a determination unit 104 (corresponding to a determination unit) for determining whether or not ΔTS4 or less and a density adjustment unit 110 described later. Adjustment instruction unit 105 (corresponding to an adjustment instruction unit) for performing color adjustment, a timing setting unit 106 (corresponding to a timing setting unit) for setting density adjustment timing, a patch image storage unit 107 for storing patch image data, and each color And a density adjusting unit 110 (corresponding to density adjusting means) for adjusting the density of each toner image.

  Here, the control unit 100 includes a CPU (Central Processing Unit), a ROM (Read Only Memory) storing a control program, a RAM (Random Access Memory) used as a work area of the CPU, and the like. As a dot count unit 101, a dot number storage unit 102, a consumption amount detection unit 103, a determination unit 104, an adjustment instruction unit 105, a timing setting unit 106, a patch image storage unit 107, and a density adjustment unit 110 It functions.

  The dot count unit 101 counts the number of dots of each color of toner included in the image data to obtain the count values TK, TY, TM, and TC, and each color (here, black (K), yellow (Y), magenta ( M) and four cyan (C) colors) count values TK, TY, TM, and TC are stored in the dot number storage unit 102, respectively. Specifically, the dot count unit 101 counts the number of dots to which laser light is turned on (irradiated) by the exposure units 33K to 33C.

The consumption amount detection unit 103 uses the toner consumption amounts ΔTK, TK, TKi, TYi, TMi, TCi of the previous density adjustment timing and the count values TKj, TYj, TMj, TCj of the current density adjustment timing. ΔTY, ΔTM, and ΔTC are calculated. Specifically, the consumption amounts ΔTK, ΔTY, ΔTM, and ΔTC of the toners of the respective colors are calculated using the following equations (1) to (4).
ΔTK = C1 × | TKj−TKi | (1)
ΔTY = C2 × | TYj−TYi | (2)
ΔTM = C3 × | TMj−TMi | (3)
ΔTC = C4 × | TCj−TCi | (4)
Here, the constants C1 to C4 are preset constants (for example, an average value of toner consumption per dot).

  The determination unit 104 determines whether the toner consumption amounts ΔTK, ΔTY, ΔTM, and ΔTC of the respective colors are equal to or less than predetermined threshold values ΔTS1 to ΔTS4, respectively. Here, it is assumed that the threshold values ΔTS1 to ΔTS4 are set to predetermined values (for example, 3 mg) in advance.

  When the determination unit 104 determines that the toner consumption amounts ΔTK, ΔTY, ΔTM, and ΔTC of the respective colors are equal to or less than the predetermined thresholds ΔTS1 to ΔTS4, the adjustment instruction unit 105 is equal to or less than the predetermined thresholds ΔTS1 to ΔTS4. For the developing units 34K, 34Y, 34M, and 34C corresponding to the toner determined to be, the instruction is given to the density adjustment unit 110 to skip the adjustment at the current density adjustment timing.

  That is, the developing units 34K, 34Y, 34M, and the like corresponding to toners whose toner consumption amounts ΔTK, ΔTY, ΔTM, and ΔTC from the previous density adjustment timing to the current density adjustment timing are equal to or less than a predetermined threshold value ΔTS1 to ΔTS4. Regarding 34C, the adjustment at the current density adjustment timing is skipped (adjustment is not performed).

  The timing setting unit 106 accepts an operation input from the outside and sets the density adjustment timing. Here, it is assumed that the number of printed sheets is set by accepting an operation input from the outside, and the density adjustment timing is set every time the accumulated number of printed sheets increases by the set number of printed sheets (for example, 100 sheets). .

  The patch image storage unit 107 is a patch for each color (four colors of black (K), yellow (Y), magenta (M), and cyan (C)) printed on the transfer belt 21 by the density adjustment unit 110. It stores image data.

  The density adjusting unit 110 includes a patch image forming unit 111 that forms a patch image on the transfer belt 21, a density measuring unit 112 that measures the density of the patch image formed on the transfer belt 21 via the density sensor 70, and And a correction unit 113 that adjusts the developing bias value based on the measured density.

  The patch image forming unit 111 adjusts the patch image data of each color (other than the color determined to skip the adjustment at the current density adjustment timing) as the adjustment target by the adjustment instruction unit 105, respectively. And a patch image is formed on the transfer belt 21.

  The density measuring unit 112 measures the density of each color patch image formed on the transfer belt 21 via the density sensor 70.

  The correcting unit 113 adjusts the developing bias values of the corresponding developing units 34K, 34Y, 34M, and 34C based on the density of each color measured by the density measuring unit 112, and corrects the density of the formed image. Is.

  3 and 4 are flowcharts illustrating an example of the operation of the control unit 100 of the color printer 1. First, as shown in FIG. 3, whether or not it is the density adjustment timing set by the timing setting unit 106 by the adjustment instruction unit 105 (in this case, whether the number of printed sheets after the previous density adjustment timing has reached 100 sheets). No) is determined (step S101). If it is determined that it is not the density adjustment timing (NO in step S101), the process is set to a standby state.

  If it is determined that it is the density adjustment timing (YES in step S101), the consumption amount detection unit 103 calculates toner consumption amounts ΔTK, ΔTY, ΔTM, and ΔTC of each color (step S103). Then, the determination unit 104 determines whether or not the consumption amount ΔTK of black (K) toner is equal to or less than the threshold value ΔTS1 (step S105). If it is determined that it is not less than or equal to the threshold value ΔTS1 (exceeds the threshold value ΔTS1) (NO in step S105), the developing unit 34K is operated by the density adjustment unit 110 (step S107), and black (K) calibration is performed. Processing is performed (step S109). If it is determined that it is equal to or less than the threshold value ΔTS1 (YES in step S105), the adjustment instruction unit 105 instructs the density adjustment unit 110 to skip the adjustment at the current density adjustment timing (= developing unit 34K). Is stopped) (step S111).

  When the processing in step S109 or step S111 is completed, the determination unit 104 determines whether the consumption amount ΔTY of yellow (Y) toner is equal to or less than the threshold value ΔTS2 (step S113). If it is determined that it is not less than or equal to the threshold value ΔTS2 (exceeds the threshold value ΔTS2) (NO in step S113), the developing unit 34Y is operated by the density adjustment unit 110 (step S115), and yellow (Y) calibration is performed. Processing is performed (step S117). If it is determined that it is equal to or less than the threshold value ΔTS2 (YES in step S113), the adjustment instruction unit 105 instructs the density adjustment unit 110 to skip the adjustment at the current density adjustment timing (= developing unit 34Y). Is stopped) (step S119).

  Next, as shown in FIG. 4, when the processing of step S117 or step S119 is completed, the determination unit 104 determines whether the magenta (M) toner consumption amount ΔTM is equal to or less than the threshold value ΔTS3. This is performed (step S121). If it is determined that it is not less than or equal to the threshold value ΔTS3 (exceeding the threshold value ΔTS3) (NO in step S121), the developing unit 34M is operated by the density adjustment unit 110 (step S123), and magenta (M) calibration is performed. Processing is performed (step S125). If it is determined that the value is equal to or less than the threshold value ΔTS3 (YES in step S121), the adjustment instruction unit 105 instructs the density adjustment unit 110 to skip the adjustment at the current density adjustment timing (= developing unit 34M). Is stopped) (step S127).

  Next, when the process of step S125 or step S127 is completed, the determination unit 104 determines whether or not the cyan (C) toner consumption amount ΔTC is equal to or less than the threshold value ΔTS4 (step S129). . If it is determined that it is not less than the threshold value ΔTS4 (is greater than the threshold value ΔTS4) (NO in step S129), the developing unit 34C is operated by the density adjustment unit 110 (step S131), and cyan (C) calibration is performed. Processing is performed (step S133), and the processing is terminated. If it is determined that it is equal to or smaller than the threshold value ΔTS4 (YES in step S129), the adjustment instruction unit 105 instructs the density adjustment unit 110 to skip the adjustment at the current density adjustment timing (= the developing unit 34C Is stopped) (step S135), and the process is terminated.

  FIG. 5 is a detailed flowchart illustrating an example of the calibration process performed in steps S109, 117, 125, and 133 in the flowcharts of FIGS. The following processing is all performed by the density adjustment unit 110. First, the patch image forming unit 111 forms a black (K) (or yellow (Y), magenta (M), cyan (C)) patch image on the transfer belt 21 (step S201). Then, the density of the patch image formed on the transfer belt 21 is measured by the density measuring unit 112 via the density sensor 70 (step S203). Next, the correcting unit 113 adjusts the developing bias value of the corresponding developing unit 34K (or the developing units 34Y, 34M, and 34C) based on the density measured in step S203 (step S207), and the process is returned. The

  In this way, the current density of the developing units 34K, 34Y, 34M, and 34C corresponding to the toners for which the consumption amounts ΔTK, ΔTY, ΔTM, and ΔTC of the toners of the respective colors are determined to be equal to or less than the predetermined threshold values ΔTS1 to ΔTS4 are determined. Since the adjustment at the adjustment timing is skipped, the toner consumption and the work time are reduced.

  Here, since the developing unit 34 having a small amount of toner consumption ΔTK, ΔTY, ΔTM, and ΔTC has a short operation time (= integrated time during which the developing operation is performed), it is considered that the variation in development characteristics is relatively small. Therefore, by determining that the developing unit 34 having a small amount of toner consumption ΔTK, ΔTY, ΔTM, and ΔTC is relatively low in density adjustment and skipping density adjustment at the current density adjustment timing, Toner consumption and working time are reduced.

  Further, since the timing setting unit 106 accepts an external input and sets the density adjustment timing, the density adjustment timing desired by the operator or the like can be set.

  Furthermore, since the timing setting unit 106 sets the timing when the accumulated number of recording sheets P on which the image is formed is increased by a predetermined number (here, 100) as the density adjustment timing, an appropriate density adjustment timing is set. Is set.

  In addition, based on the previous density adjustment timing count values TKi, TYi, TMi, and TCi and the current density adjustment timing count values TKj, TYj, TMj, and TCj, toner consumption amounts ΔTK, ΔTY, ΔTM, and ΔTC are obtained. Since it is calculated, the toner consumption is calculated easily and accurately.

  In addition, this invention can take the following aspects.

  (A) In this embodiment, the case where the image forming apparatus is the printer 1 has been described. However, another type of image forming apparatus (for example, a facsimile, a copying machine, etc.) may be used.

  (B) In the present embodiment, the case where the printer 1 is the tandem printer 1 in which the photosensitive drums 31K, 31Y, 31M, and 31C are arranged for the number of colors (here, four) has been described. The drum may be a single printer 1.

  (C) In this embodiment, the density adjusting unit 110 continuously adjusts each color (here, four colors of black (K), yellow (Y), magenta (M), and cyan (C)) ( Although the case of performing in series has been described, it may be performed in parallel (in parallel).

  (D) In the present embodiment, the consumption amount detection unit 103 is based on the previous density adjustment timing count values TKi, TYi, TMi, TCi and the current density adjustment timing count values TKj, TYj, TMj, TCj. Although the case where the toner consumption amounts ΔTK, ΔTY, ΔTM, and ΔTC of the respective colors are calculated has been described, the toner consumption amounts ΔTK, ΔTY, ΔTM, and ΔTC of the respective colors may be calculated by other methods.

  For example, the printer 1 supplies toner to the developing units 34K, 34Y, 34M, and 34C from toner containers 341K, 341Y, 341M, and 341C that store toner of each color, and toner containers 341K, 341Y, 341M, and 341C, respectively. From the previous density adjustment timing to the current density adjustment timing. Alternatively, the consumption amounts ΔTK, ΔTY, ΔTM, and ΔTC of the toners of the respective colors may be calculated based on the toner supply amount by the supply roller.

  In this case, since the toner consumption amounts ΔTK, ΔTY, ΔTM, and ΔTC are calculated based on the toner replenishment amount from the previous density adjustment timing to the current density adjustment timing, the toner is simply Consumption amounts ΔTK, ΔTY, ΔTM, and ΔTC are calculated.

  Further, for example, when the printer 1 determines that each color of toner is included in the image data each time an image is formed, and when it is determined that each color of toner is included in the image data A consumption number counting unit that counts the number of image formations and counts the number of sheets and a sheet number storage unit that stores a count value of the number of toner colors are provided. The consumption amount detection unit 103 counts the number of sheets at the previous density adjustment timing. The toner consumption amounts ΔTK, ΔTY, ΔTM, and ΔTC may be calculated based on the value and the count value of the number of sheets at the current density adjustment timing.

  In this case, the toner consumption amounts ΔTK, ΔTY, ΔTM, and ΔTC are calculated based on the count value of the number of sheets at the previous density adjustment timing and the count value of the number of sheets at the current density adjustment timing. Toner consumption amounts ΔTK, ΔTY, ΔTM, and ΔTC are calculated.

  (E) Although the case where the threshold values ΔTS1 to ΔTS4 are set in advance has been described in the present embodiment, the threshold values ΔTS1 to ΔTS4 may be set based on an operation input from the outside. In this case, it is possible to set a criterion for determining whether or not to skip the adjustment at the density adjustment timing from the outside, so that convenience is improved.

1 is a schematic diagram illustrating an example of a configuration of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a block diagram illustrating an example of a functional configuration of the color printer illustrated in FIG. 1. 6 is a flowchart (first half) illustrating an example of the operation of the control unit of the color printer. 5 is a flowchart (second half) illustrating an example of the operation of the control unit of the color printer. 6 is a detailed flowchart illustrating an example of calibration processing performed in steps S109, 117, 125, and 133 in the flowcharts of FIGS.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Color printer 30 Image formation part 31 (31K, 31Y, 31M, 31C) Photosensitive drum 34 (34K, 34Y, 34M, 34C) Development part 70 Density sensor 100 Control part 101 Dot count part (dot count means)
102 dot number storage unit (dot number storage means)
103 Consumption detection unit (consumption detection means)
104 determination part (determination means)
105 Adjustment instruction section (adjustment instruction means)
106 Timing setting section (timing setting means)
107 Patch Image Storage Unit 110 Density Adjustment Unit (Density Adjustment Unit) ”
111 Patch Image Forming Unit 112 Density Measuring Unit 113 Correction Unit 200 Printing Unit 300 Scanner Unit 400 Image Memory

Claims (7)

An electrostatic latent image is formed on the surface of a photosensitive drum rotatably supported, and a toner image formed by attaching two or more predetermined number of different color toners to the formed electrostatic latent image is used as a transfer material. An image forming apparatus for forming a color image by transferring to
The predetermined number of developing means for generating a toner image on the photosensitive drum for each of the predetermined number of toners;
Density adjusting means for adjusting the density of each color toner image generated by the predetermined number of developing means;
An adjustment instructing unit for instructing the density adjusting unit to adjust the density of each color toner image generated by the developing unit at a predetermined density adjustment timing;
Consumption amount detecting means for determining the consumption amount of the toner between the previous density adjustment timing and the current density adjustment timing for each of the predetermined number of toners;
Determination means for determining whether or not the consumption is equal to or less than a predetermined value set in advance,
The adjustment instruction means instructs the density adjustment means to skip the adjustment at the current density adjustment timing for the developing means corresponding to the toner whose consumption is determined to be equal to or less than the predetermined value by the determination means. An image forming apparatus characterized by instructing.   The image forming apparatus according to claim 1, further comprising a timing setting unit that receives an operation input from the outside and sets the density adjustment timing.   The image forming apparatus according to claim 2, wherein the timing setting unit sets a timing at which the cumulative number of transfer materials on which an image has been formed by a predetermined number as a density adjustment timing. Dot count means for counting and integrating the number of dots of each color of toner included in the image data each time an image is formed;
Dot number storage means for storing the dot count value of each color by the dot count means for each density adjustment timing;
4. The consumption amount detecting unit calculates the consumption amount based on a dot count value at a previous density adjustment timing and a dot count value at a current density adjustment timing. The image forming apparatus described. Replenishing means for replenishing toner to the developing means from a toner container that stores toner of each color;
Replenishment amount calculation means for obtaining a replenishment amount of toner to the developing means by the replenishment means,
The said consumption amount detection means calculates the said consumption amount based on the replenishment amount of the toner by the said replenishment means between the previous density adjustment timing and this density adjustment timing. The image forming apparatus according to any one of the above. Color determination means for determining whether or not each color of toner is included in image data each time an image is formed;
A number counting means for counting the number of sheets by adding up the number of image formations when it is determined that each color of toner is included in the image data;
Sheet number storage means for storing a count value of the number of sheets for each color of toner,
4. The consumption amount detection unit calculates the consumption amount based on a count value of the number of sheets at the previous density adjustment timing and a count value of the number of sheets at the current density adjustment timing. An image forming apparatus according to claim 1.   7. The image forming apparatus according to claim 1, wherein the image forming apparatus is a tandem type color image forming apparatus in which a predetermined number of photosensitive drums are disposed.

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