JP2011048095A - Color material supply device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress a situation in which an amount of color material contained in a developing means for developing an image is run short of when forming an image group comprising a plurality of images on a plurality of recording media. <P>SOLUTION: A controller 11 of the image forming apparatus 1 calculates toner consumption on the basis of a ratio (hereinafter referred to as image density) of a pixel group constituting an image to be formed on recording paper in an area where the image can be formed on the recording paper. The controller 11 specifies an amount of toner equivalent to the toner consumption as an amount of toner (toner supply amount) to be supplied to a developing device. The controller 11 controls an image forming part 16 to supply the toner used to form all the images of a document comprising a plurality of pages to the developing device D in parallel with processing for forming the image of the document on the recording paper. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a color material supply device and an image forming apparatus.

  In the image forming apparatus, when the density of the color material accommodated in the developing device is remarkably lowered, there is a problem in that the quality of the image is deteriorated, such as unevenness in the density of the image formed on the recording paper. For example, in Patent Document 1, the amount of color material consumed when an image is formed on each recording sheet is predicted for each recording sheet, and the predicted amount of color material is developed in accordance with the image formation timing for each recording sheet. Refilling the vessel is disclosed.

JP 2006-220999 A

  The present invention suppresses the occurrence of a situation where the amount of color material contained in the developing means for developing an image is insufficient when an image group consisting of a plurality of images is formed on a plurality of recording media. Objective.

According to a first aspect of the present invention, there is provided color material amount calculating means for calculating the total amount of color material used for developing an image group formed on a plurality of recording media, and development using a developer containing the color material. A replenishing unit that replenishes the unit with a color material amount calculated by the color material amount calculating unit, the temporal change in the amount of color material used for the sequential development by the developing unit for the image group The color material amount calculated by the color material amount calculating means is supplied to the developing means in a replenishment distribution in which the total amount of color material calculated by the color material amount calculating means is divided into a plurality of times. A color material replenishing device comprising replenishing means for replenishing.
According to a second aspect of the present invention, in the configuration according to the first aspect, the replenishing means equalizes the color material replenishment amount per unit time with the color material amount calculated by the color material amount calculation means. In addition, the color material replenishing apparatus is characterized in that the developing means is replenished continuously in time after the development of the image group is started.
According to a third aspect of the present invention, in the configuration according to the first aspect, the replenishing unit replenishes the amount of color material used for development per unit time in the developing unit per unit time by the replenishing unit. When the amount of the color material is smaller than the amount of the color material, the amount of the color material calculated by the color material amount calculation unit is changed by the replenishment unit so that the amount of the color material used for development per unit time is the unit. Compared to the case where the amount of the color material to be replenished per hour is larger, the color material replenishment apparatus is characterized in that the developer is replenished in many times.
According to a fourth aspect of the present invention, in the configuration according to the first or second aspect of the present invention, the measurement unit includes a measuring unit that measures the amount of the color material accommodated in the developing unit, and the replenishing unit is measured by the measuring unit. When the amount of the color material is equal to or greater than the first threshold value, the replenishment of the color material is stopped, and the amount of the color material measured by the measuring unit is less than the second threshold value which is smaller than the first threshold value. In this case, the color material replenishing apparatus restarts the color material replenishment.
According to a fifth aspect of the present invention, there is provided the color material replenishing device according to any one of the first to fourth aspects, an image holding body for holding an image, a charging means for charging the image holding body, and the charging means. An electrostatic latent image forming unit that forms an electrostatic latent image by exposing the image carrier charged by the electrostatic latent image and an electrostatic latent image formed by the electrostatic latent image forming unit Developing means for developing using the color material replenished by the transfer means, transfer means for transferring a plurality of images obtained by development of the developing means to a corresponding plurality of recording media, and each recording medium by the transfer means A fixing unit that fixes the transferred image on the recording medium, and the exposure unit changes the light amount when performing exposure according to the density of the color material in the developer contained in the developing unit. An image forming apparatus characterized by .

According to the first aspect of the present invention, when the amount of the color material required for developing the image group is calculated for each recording medium, and this amount of the color material is supplied to the developing means in accordance with the development timing for each recording medium. In comparison, it is possible to suppress the occurrence of a situation where the amount of the color material accommodated in the developing unit is insufficient.
According to the invention of claim 2, the occurrence of a situation in which the concentration of the color material in the developer stored in the developing unit changes abruptly as compared with the case where the replenishment amount per unit time is varied. Compared with the case where the color material is replenished intermittently in time, the color material in the developing means can be used even when a high density image is continuously developed. The effect of suppressing the occurrence of shortage is high.
According to the third aspect of the present invention, since the amount of the color material used for development per unit time in the developing unit is smaller than the amount of the color material replenished per unit time by the replenishing unit, Even in a situation where the concentration of the color material in the developer accommodated is likely to be high, it is possible to suppress the occurrence of a situation in which the concentration of the color material rapidly increases.
According to the fourth aspect of the present invention, it is possible to suppress the occurrence of a situation in which the amount of the color material accommodated in the developing unit becomes excessive as compared with the amount of the color material required for developing the image group. .
According to the fifth aspect of the present invention, when an image group composed of a plurality of images is formed on a plurality of recording media, the amount of the coloring material required for forming the image is calculated for each recording medium, and this amount of the coloring material is calculated. As compared with the case where the developing unit is replenished with the timing of image formation on each recording medium, each image is recorded while suppressing the occurrence of a situation where the amount of color material contained in the developing unit is insufficient. It can be formed on a medium.

1 is a block diagram illustrating a configuration of an image forming apparatus 1 according to an embodiment of the present invention. It is a figure which shows the structure of the image development part 164 which concerns on the embodiment. 4 is a flowchart for explaining the operation of the image forming apparatus 1 according to the embodiment. FIG. 6 is a diagram illustrating a state of image formation, toner supply, and toner density transition according to the embodiment. FIG. 6 is a diagram illustrating a state of toner supply and toner density transition when a toner consumption amount is calculated for each page of a document and the toner consumption amount for each page is set as a toner supply amount for each page. FIG. 10 is a diagram illustrating a state of toner replenishment and toner density transition according to a modification of the embodiment.

Embodiments of the present invention will be described below with reference to the drawings.
(1) Configuration FIG. 1 is a block diagram illustrating a configuration of the image forming apparatus 1.
The image forming apparatus 1 uses, for example, printing or scanning to form an image on a recording sheet that is an example of a recording medium using toner that is an example of a color material, or to read an image formed on the recording sheet. It is a device that integrates functions such as copying. The image forming apparatus 1 includes a control unit 11, a storage unit 12, an operation unit 13, a display unit 14, an image reading unit 15, and an image forming unit 16.

  The control unit 11 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory), and the CPU executes a program stored in the ROM or the storage unit 12. Thus, each part of the image forming apparatus 1 is controlled. The storage unit 12 is a non-volatile auxiliary storage device such as an HD (Hard Disk), and stores various programs and data. The operation unit 13 includes a power switch and a plurality of keys. The operation unit 13 receives a user operation and supplies a signal corresponding to the operation to the control unit 11. The display unit 14 includes a VRAM (Video RAM), a liquid crystal display, and a liquid crystal drive circuit. Based on information supplied from the control unit 11, the display unit 14 displays the progress of processing, information for guiding operations to the user, and the like. To do. The image reading unit 15 includes an optical system member constituted by a CCD (Charge Coupled Device), reads an image formed on a recording sheet by the optical system member, and generates image data representing the read image.

  The image forming unit 16 includes a photosensitive drum 161, a charging unit 162, an exposure unit 163, a developing unit 164, a transfer unit 165, and a fixing unit 166, and an image generated by the image reading unit 15. An image based on the data and image data received from the outside by a communication unit (not shown) is formed on a recording sheet. The photoconductive drum 161 is an example of an image holding body that holds an image, and a photoconductive film in which a conductive drum base and an OPC (Organic Photo Conductor) are formed on the surface of the drum base. And a cylindrical member whose main scanning direction is the longitudinal direction. The main scanning direction is a scanning direction when the exposure unit 163 performs exposure scanning in accordance with the rotation of the polygon mirror, and is a direction that intersects the recording paper conveyance direction (sub-scanning direction). The photosensitive drum 161 functions as an example of an image carrier that rotates at a predetermined peripheral speed with the center of the drum base as a rotation axis while maintaining a state in contact with the intermediate transfer belt. The charging unit 162 is a charging member whose surface is in contact with the surface of the photosensitive drum 161, and charges the surface of the photosensitive drum 161 to a predetermined polarity and potential while rotating according to the rotation of the photosensitive drum 161. It functions as an example of charging means. The exposure unit 163 is an example of an electrostatic latent image forming unit. The exposure unit 163 includes a laser emission source, a polygon mirror, and the like, and irradiates an image-modulated laser beam toward the peripheral surface of the photosensitive drum 161 to generate an electrostatic latent image. Form. An electrostatic latent image is a latent image formed by the difference between the potential of an exposed area and the potential of an unexposed area.

  The transfer unit 165 is an example of a transfer unit, and includes an intermediate transfer belt, a support roll, a primary transfer roll, a secondary transfer roll, and a counter roll. The intermediate transfer belt is an endless belt member, and the inner peripheral surface of the intermediate transfer belt is revolved while being stretched by a plurality of support rolls, a primary transfer roll, and a secondary transfer roll. The primary transfer roll is provided at a position facing the photosensitive drum 161 with the intermediate transfer belt interposed therebetween, and primarily transfers the toner image formed on the surface of the photosensitive drum 161 onto the outer peripheral surface of the intermediate transfer belt. The secondary transfer roll secondarily transfers the toner image transferred to the outer peripheral surface of the intermediate transfer belt onto a recording sheet in a region where the intermediate transfer belt is sandwiched between the secondary transfer roll and the opposing roll. The fixing unit 166 is an example of a fixing unit, and includes a heating roll and a pressure roll that face each other across a conveyance path through which a recording sheet is conveyed. The fixing unit 166 fixes the toner image on the recording paper by applying pressure and heat to the recording paper on which the toner image is secondarily transferred by a heating roll and a pressure roll.

FIG. 2 is a diagram illustrating the structure of the developing unit 164.
The developing unit 164 is an example of a developing unit. Containers Cy, Cm, Cc, and Ck that store toner of each color of yellow (Y), magenta (M), cyan (C), and black (K), and these Development units Dy, Dm, Dc, and Dk to which toner is supplied from the respective containers Cy, Cm, Cc, and Ck. The developing devices Dy, Dm, Dc, and Dk develop the electrostatic latent image formed on the photosensitive drum 161 at a predetermined position facing the photosensitive drum 161. Since the developing devices Dy, Dm, Dc, and Dk have almost the same configuration, they are referred to as a developing device D when there is no need to distinguish between them. Similarly, since the containers Cy, Cm, Cc, and Ck have almost the same configuration, they are referred to as a container C when there is no need to distinguish between them.

  In this developing device D, the ratio of the amount of toner to the developer (hereinafter referred to as toner) is measured by measuring the magnetic permeability that changes in accordance with the amount of carrier that is a magnetic material in a two-component developer having toner and carrier. A toner density sensor D13 for calculating the density). The toner density sensor D13 functions as an example of a measurement unit. The container C is a member that is detachable from the developing unit D, and includes a cylindrical casing C1 that stores toner of each color and that extends in the main scanning direction, and a transport tool C2 that is stored in the casing C1. I have. The transport tool C2 is, for example, a wire wound spirally in accordance with the inner diameter of the housing C1. The transporting tool C2 is rotated in the direction of arrow i in the figure by driving means such as a motor (not shown), so that the toner contained in the casing C1 is provided at the end of the casing C1. It conveys to the discharge port C3 which is an opening part, stirring. The toner discharged from the discharge port C3 of the container C is supplied to the adjustment chamber D1 of the developing device D.

  The adjusting chamber D1 of the developing device D is formed in a cylindrical shape having the main scanning direction as a longitudinal direction. In the adjustment chamber D1, an adjustment chamber inlet D3 communicating with the discharge port C3 of the container C and an adjustment chamber outlet D4 communicating with the developing chamber D2 are formed at both ends in the longitudinal direction. The adjusting chamber D1 is provided with a replenishing screw D5 that is a conveying member. When the replenishing screw D5 is rotated in the direction of the arrow e in the figure, the replenishing screw D5 has a spiral blade for conveying the toner in the adjusting chamber D1 from the adjusting chamber inlet D3 toward the adjusting chamber outlet D4. The size and shape of the replenishing screw D5 and the number of revolutions per unit time are such that the adjusting chamber is rotated once when the replenishing screw D5 is rotated in the adjusting chamber D1 when a sufficient amount of toner exceeds a predetermined amount. It is designed so that a predetermined amount of toner is supplied from D1 to the developing chamber D2.

  To the developing chamber D2 of the developing device D, toner is supplied from the adjusting chamber D1, and a carrier is supplied from a supply source (not shown). The developing chamber D2 is provided with a partition D11 extending in the main scanning direction, and the partition D11 divides the developing chamber D2 into a first developing chamber D9 and a second developing chamber D10. However, a hole is provided in one end and the other end in the longitudinal direction of the partition wall D11, and the first developing chamber D9 and the second developing chamber D10 communicate with each other through the hole. Yes.

  The first developing chamber D9 is provided with a first stirring screw D6 having a longitudinal direction in the main scanning direction. The first agitating screw D6 rotates in the direction of the arrow f in the drawing, so that the toner and carrier (hereinafter collectively referred to as a developer) in the first developing chamber D9 are transferred to the first developing chamber D9. It is a conveyance member conveyed in the direction which goes to the other edge part from one edge part of the longitudinal direction. The second developing chamber D10 is provided with a second stirring screw D7 and a developing roll D8 having a longitudinal direction in the main scanning direction. The second agitating screw D7 rotates in the direction of the arrow g in the drawing, so that the developer in the second developing chamber D10 is transferred from the other end in the longitudinal direction of the second developing chamber D9 to one end. It is a conveyance member conveyed in the direction which goes to. That is, the first stirring screw D6 and the second stirring screw D7 respectively convey the developer in the developing chamber D2 by conveying the developer in opposite directions. Further, the first stirring screw D6 and the second stirring screw D7 charge the developer by stirring while conveying the developer. The developing roll D8 is composed of a magnet roll arranged in a fixed state inside and a developing sleeve provided rotatably on the outer periphery of the magnet roll. Further, the developing roll D8 attracts the developer to the surface by the magnetic attraction force of the magnet roll, and develops the toner by attaching the toner to an area corresponding to the electrostatic latent image formed on the surface of the photosensitive drum 161. Do.

A drive motor D12 (not shown) provided in the vicinity of the developing device D is a device that converts electrical energy into mechanical energy (hereinafter referred to as power), and supplies power according to a signal input from the control unit 11. generate. The power generated by the drive motor D12 is transmitted to the conveying tool C2 and the replenishing screw D5 by power transmission means (not shown) such as a gear and a shaft. Therefore, the control unit 11 controls the drive (for example, the rotation time and the rotation speed) of the conveying tool C2 and the replenishing screw D5 by controlling the driving motor D12, and further the toner replenished from the container C to the developing device D. It functions as an example of replenishment means for controlling the amount of water. The amount of toner that can be replenished from the container C to the developing device D per unit time (hereinafter referred to as replenishment capability) is determined in advance according to the shape of the transport tool C2 and the replenishment screw D5, the output of the drive motor D12, and the like. And stored in the storage unit 12. A state in which the controller 11 controls the drive motor D12 to supply toner from the container C to the developing device D is referred to as replenishment ON, and a state in which toner is not replenished is referred to as replenishment OFF.
In the configuration described above, the control unit 11, the casing C1, the transport tool C2, the adjustment chamber D1, and the supply screw D5 function as an example of a color material supply device.

(2) Operation FIG. 3 is a flowchart for explaining the operation of the image forming apparatus 1.
The control unit 11 of the image forming apparatus 1 determines whether or not it has been instructed to perform a process of forming an image based on image data received from the outside on a recording sheet (hereinafter, this process is referred to as printing) ( In step S301, the determination process in step S301 is repeated until a print instruction is issued (step S301; NO). Here, when the user operates the operation unit 13 to instruct printing of a document covering, for example, a plurality of pages, the control unit 11 detects that a printing instruction has been given (step S301; YES). Then, the control unit 11 calculates the amount of toner (hereinafter referred to as toner consumption) used to form an image representing the document on the recording paper. This toner consumption amount is calculated based on the ratio (hereinafter referred to as image density) of the pixel group constituting the image formed on each recording paper in the area where the image on each recording paper can be formed. The For example, if the document has 10 pages in total, the first page to the fifth page have an image density of 15%, and the sixth page to the tenth page have an image density of 85%. , 5 times the amount of toner that can cover 15% of the image-forming area on the recording paper and 5 times the amount of toner that can cover 85% of the image-forming area on the recording paper This is the toner consumption. Therefore, the control unit 11 is an example of a color material amount calculation unit that calculates the total amount of color materials used for development. The amount of toner stored in the developing device D is reduced by an amount corresponding to the toner consumption calculated as described above. When the amount of toner stored in the developing device D is insufficient, there arises a problem that the print quality is deteriorated, such as unevenness in the density of the image formed on the recording paper. Therefore, the control unit 11 specifies the amount of toner corresponding to the toner consumption amount as the amount of toner to be replenished from the container C to the developing device D (hereinafter referred to as toner replenishment amount) (step S302). As described above, the control unit 11 calculates the toner consumption amount for each page of the document, and does not set the toner consumption amount for each page as the toner replenishment amount for each page. And the toner consumption amount is set as the toner replenishment amount of the entire document.

  Next, the control unit 11 determines whether or not an instruction to stop the image formation or a failure that has to stop the image formation has occurred (step S303). When the control unit 11 determines that the corresponding event has occurred and it is necessary to stop the image formation (step S303; YES), the control unit 11 ends the process without performing the processes from step S304 to step S307. To do. On the other hand, when the control unit 11 determines that the corresponding event has not occurred and it is not necessary to stop the image formation (step S303; NO), the control unit 11 controls the image forming unit 16 to control the image according to the image data. Is formed on the recording paper, and the driving motor D12 is controlled to supply toner from the container C to the developing device D (step S304). The toner replenished at this time is an amount corresponding to the toner replenishment amount specified in step S302 described above. Therefore, the toner density inside the developing device D is increased by performing the process of step S304.

  Here, an operation in which the image forming unit 16 forms an image will be described. First, the exposure unit 163 irradiates the surface of the photosensitive drum 161 charged with a predetermined potential with a laser beam corresponding to the image data. An electrostatic latent image is formed on the surface of the photosensitive drum 161 by changing the potential corresponding to the exposure amount of the laser beam. The developing unit 164 performs development by transferring toner charged to a polarity opposite to that of the electrostatic latent image to the electrostatic latent image formed on the surface of the photosensitive drum 161. Here, the amount of toner transferred to the surface of the photosensitive drum 161 correlates with the exposure amount in the exposure unit 163 and the toner concentration of the toner stored in the developing unit 164 (more specifically, the developing device D). It will be. More specifically, the amount of toner transferred to the surface of the photosensitive drum 161 increases as the exposure amount in the exposure unit 163 increases, and as the toner concentration of the toner stored in the developing device D increases. Become more. Therefore, the control unit 11 controls the exposure unit 163 to decrease the exposure amount when the toner density of the developing device D is high and to increase the exposure amount when the toner concentration of the developing device D is low. That is, the light amount when the exposure unit 163 performs exposure is a light amount according to the amount of toner accommodated in the developing device D.

  Returning to the description of FIG. The control unit 11 measures the toner density of the developing device D using the detection value by the toner density sensor D13 disposed inside the developing device D at a predetermined timing (step S305). The predetermined timing may be every predetermined time or every time an image is formed on a recording sheet. Next, the control unit 11 determines whether the toner density measured in step S305 is equal to or higher than the upper threshold value (step S306). Here, the upper threshold value is provided in order to prevent the occurrence of a phenomenon in which the toner density in the developing device D increases and the toner scatters and stains the inside of the image forming apparatus 1 and the recording paper. The threshold value is a value stored in advance in the storage unit 12. When the controller 11 determines that the toner density measured in step S305 is equal to or higher than the upper threshold (step S306; YES), the controller 11 controls the drive motor D12 to supply toner from the container C to the developing device D. Is temporarily stopped (step S310). That is, this upper threshold value is an example of a first threshold value. On the other hand, the controller 11 continues to form an image on the recording paper by controlling the image forming unit 16 while the toner supply is temporarily stopped. Therefore, the toner density inside the developing device D decreases according to the processing for forming an image.

  As in step S305 described above, the control unit 11 measures the toner density inside the developing device D using the detection value by the toner density sensor D13 at a predetermined timing (step S309). Then, the control unit determines whether the toner density measured in step S309 is equal to or higher than the lower threshold value (step S308). Here, the lower threshold value is a value indicating a predetermined toner density for the control unit 11 to determine whether or not the container C restarts toner supply, and is stored in the storage unit 12. . When the control unit 11 determines that the toner density measured in step S309 is equal to or higher than the lower threshold (step S308; NO), the control unit 11 performs the process of step S309 again without causing the container C to resume toner supply. On the other hand, when the control unit 11 determines that the toner density is less than the lower threshold value (step S308; YES), the control unit 11 controls the drive motor D12 to restart the toner supply from the container C, so that the steps after step S303 are performed. The process is performed again. That is, this lower threshold value is an example of a second threshold value.

  On the other hand, when the control unit 11 determines that the toner density measured in step S305 is less than the upper threshold (step S306; NO), the image forming unit 16 forms an image, and the container C develops the image. It is determined whether or not all the processes for supplying toner to the container D have been completed (step S307). When the control unit 11 determines that either one of the process of forming an image by the image forming unit 16 and the process of supplying toner from the container C to the developing unit D is not completed (step S307; NO). The processing after step S303 is performed again. Further, when the control unit 11 determines that both the process of forming an image by the image forming unit 16 and the process of supplying toner from the container C to the developing unit D have been completed (step S307; YES). The process according to the instruction from the user is terminated.

Next, the state of image formation, toner supply, and toner density transition in the processing of steps S304 to S310 will be described in detail with reference to FIG.
FIG. 4 is a diagram illustrating the state of image formation, toner supply, and toner density transition. 4 (1) to 4 (3) is a time axis, and T41 to T46 attached to the time axis indicate the same time in each figure.
FIG. 4A is a diagram illustrating the relationship between the image density of an image formed on a recording sheet and the time when each image is formed on the recording sheet. The control unit 11 controls the image forming unit 16 to form an image according to the image data on the recording paper from time T41 to T46. The images formed at this time have an image density of 15% and 85%, similar to the above-described image, and five images are formed on each recording sheet.

  Next, FIG. 4B is a diagram illustrating a relationship between toner replenishment ON / OFF control and the time required for the control. The controller 11 replenishes toner from the container C to the developing device D by controlling the drive motor D12 based on the replenishment capability per unit time stored in the storage unit 12 and the toner replenishment amount specified in step S302. The time (hereinafter referred to as replenishment time) is calculated. That is, the replenishment time is a time required for the toner amount corresponding to the toner replenishment amount to be replenished from the container C to the developing device D, and is calculated from a value obtained by dividing the toner replenishment amount by the replenishment capability. . It is assumed that the replenishment time calculated in this way is a time from time T41 to T43 as shown in the upper part of FIG. In this case, the controller 11 may control the drive motor D12 from time T41 to T43 to replenish the toner from the container C to the developing device D. However, as described above, Depending on the relationship between the toner density and the upper and lower thresholds, it is necessary to stop and restart the toner supply. The timing at which toner replenishment is started is approximately T41 as shown in the figure, but more precisely, the timing at which the developing device D starts driving for development, that is, the rotation of the conveying device C2 described above. It is time to start.

  Next, FIG. 4 (3) is a diagram showing the relationship between the transition of the toner density in the developing device D and time. This figure shows the above-described upper threshold value and lower threshold value, and there is a value called reference toner density that is smaller than these threshold values. The reference toner density is a predetermined toner density inside the developing device, and is a density which is suitable for developing an electrostatic latent image or a density slightly lower than the lowest value. The toner density in the developing device D varies depending on the replenishment capability per unit time and the toner consumption per unit time. That is, when the replenishment capability is higher than the toner consumption amount, the toner concentration in the developing device D is high, and when the replenishment capability is lower than the toner consumption amount, the toner concentration in the development device D is low. Here, the replenishment capacity per unit time is higher than the toner consumption when forming an image with an image density of 15% and lower than the toner consumption when forming an image with an image density of 85%. In this case, the toner density in the developing device D changes as shown. This will be described in more detail below.

  In a period after time T41 and before T42, the control unit 11 controls the image forming unit 16 to form an image with an image density of 15%. At this time, since the toner density in the developing device D is less than the lower threshold value, the control unit 11 controls the driving motor D12 to supply toner from the container C to the developing device D. In this case, since the replenishment capability is higher than the toner consumption amount when an image having an image density of 15% is formed, the toner density in the developing device D is higher at time T42 than at time T41.

  Next, at time T42, the control unit 11 detects that the toner density has reached the upper threshold as a result of measuring the toner density in the developing device D by the toner density sensor D13. In accordance with the detection result, the control unit 11 controls the drive motor D12 to temporarily stop the process of supplying toner from the container C to the developing device D. That is, the replenishment time calculated by the control unit 11 is the time from time T41 to T43, but replenishment is temporarily interrupted at the time T42. On the other hand, the control unit 11 controls the image forming unit 16 to continue forming an image on the recording paper, so that the toner density inside the developing device D gradually decreases. Further, at a time after time T43 and before time T44, the control unit 11 controls the image forming unit 16 to form an image with an image density of 85%. It will drop more rapidly than the time before T43.

  At time T44, the control unit 11 detects that the toner concentration in the developing device D measured by the toner concentration sensor D13 has reached the lower threshold value. In accordance with the detection result, the control unit 11 controls the drive motor D12 to restart the process of supplying toner from the container C to the developing device D. However, since the replenishment capability is lower than the toner consumption amount when forming an image having an image density of 85%, the toner density in the developing device D gradually decreases after time T44 and before time T45. Become.

  When the time from time T41 to T42 and the time from time T44 to T45 are summed, the replenishment time calculated by the control unit 11 is reached. Accordingly, the control unit 11 determines that the amount of toner supplied to the developing device D has reached the toner supply amount at time T45, and controls the driving motor D12 to supply toner from the container C to the developing device D. Stop processing. Furthermore, the control unit 11 continues the control of the image forming unit 16 until time T46 when the formation of all images corresponding to the image data is completed. The toner density at the processing end time T46 and the toner density at the processing start time (T41) are both substantially equal to the reference toner density. This is because the control unit 11 specifies the amount of toner corresponding to the toner consumption amount as the toner replenishment amount.

  In FIG. 4 (3), the manner in which the control unit 11 controls the drive motor D 12 and the image forming unit 16 based on the toner density in the developing device D has been mainly described. The exposure unit 163 is also controlled. That is, the control unit 11 controls the exposure unit 163 to decrease the exposure amount when the toner concentration in the developing device D is high and to increase the exposure amount when the toner concentration in the developing device D is low.

Here, the toner consumption amount of the entire document of a plurality of pages is calculated as in the above-described embodiment, and the toner consumption amount is not used as the toner replenishment amount required for the development of the entire document. The case where the amount is calculated and the toner consumption amount for each page is set as the toner replenishment amount per page will be described.
FIG. 5 is a diagram illustrating the state of toner supply and toner density transition when the toner consumption amount is calculated for each page of the document and the toner consumption amount for each page is set as the toner supply amount for each page. . 5 (1) to 5 (3) is a time axis, and T51a to T60c attached to this time axis indicate the same time in each figure.
FIG. 5A is a diagram illustrating the relationship between the image density of an image formed on a recording sheet and the time when each image is formed on the recording sheet. The control unit controls the image forming unit to form an image for each page on the recording paper after time T51a and before time T60b. The images formed at this time have an image density of 15% and 85%, and five images are formed on each recording sheet. For example, the image corresponding to page P1 has an image density of 15%, and is formed on the recording paper in a period after time T51a and before T51b. Further, a period after time T51b and before T52a is a period between periods in which an image is formed on a recording sheet. For example, processing such as density adjustment and toner supply is performed. Hereinafter, the period between the formation of images on the recording paper is referred to as an adjustment period.

Next, FIG. 5B is a diagram showing the relationship between toner replenishment ON / OFF control and the time required for the control.
The control unit calculates a toner consumption amount for each page, and sets the toner consumption amount for each page as a toner replenishment amount for each page. Further, the control unit calculates a replenishment time for supplying toner from the container to the developing device by controlling the drive motor from the replenishment capability per unit time stored in the storage unit and the toner replenishment amount per page. . Here, the replenishment capacity per unit time is higher than the toner consumption when forming an image with an image density of 15% and lower than the toner consumption when forming an image with an image density of 85%. To do. Then, the replenishment time is shown as the upper part of FIG. Note that the same number is assigned to the replenishment time code “H” corresponding to a page in order to clarify the association with each page.
The control unit controls the image forming unit to form an image corresponding to the page P1 having an image density of 15% on the recording paper, and at the same time controls the drive motor to store the toner corresponding to the toner replenishment amount. To the developer unit. The replenishment capacity per unit time is higher than the toner consumption when forming an image having an image density of 15%. Accordingly, the replenishment time H1 corresponding to the page P1 (period after the time T51a and before T51c) is shorter than the time (period after the time T51a and before T51b) for forming an image corresponding to the page P1. Become.
On the other hand, the control unit controls the image forming unit to form an image corresponding to page P6 having an image density of 85% on the recording paper, and at the same time controls the drive motor to supply toner corresponding to the toner replenishment amount. Assume that the developer is supplied from the container. The replenishment capacity per unit time is lower than the toner consumption when forming an image having an image density of 85%. Accordingly, the replenishment time H6 corresponding to page P6 (period after time T56a and before T56c) is longer than the time required to form an image corresponding to page P6 on the recording paper (period after time T56a and before T56b). Become. This difference time (period after time T56b and before T56c) is referred to as difference time.

Next, FIG. 5 (3) is a diagram showing the relationship between the transition of the toner density in the developing device D and time.
The controller can control the drive motor to replenish the toner from the container to the developer during the adjustment time between image formations. However, when the difference time is longer than the adjustment time, the toner consumption exceeds the replenishment capability, so that the toner replenishment cannot be made in time. That is, the toner density in the developing device D is lower than a predetermined reference toner density because the toner is not supplied for a time (hereinafter, referred to as an insufficient supply time) where the difference time is longer than the adjustment time. turn into. This state is a toner shortage state. Therefore, in order to set the toner density in the developing device D to a predetermined reference toner density, the control unit needs to perform replenishment for the short replenishment time at any timing. In FIG. 5 (3), the controller replenishes an amount of toner corresponding to the short replenishment time after all pages of the image have been formed. An amount of toner corresponding to the minute may be supplied. However, in any case, the control unit needs to perform replenishment for the short replenishment time separately from the operation of the above embodiment.

  As described above, in the replenishment method shown in FIG. 5, the toner is replenished to the developing device with a replenishment distribution depending on the temporal change in the amount of the color material used for the sequential development for the image group. Therefore, when the toner consumption amount per unit time is less than the replenishment capability, the toner concentration in the developing device is kept approximately constant, but when the toner consumption amount per unit time exceeds the replenishment capability, the toner There will be a shortage. On the other hand, in the replenishment method shown in FIG. 4 described above, the control unit 11 supplies the toner to the developing device D by a replenishment distribution that does not depend on the temporal change in the amount of color material corresponding to each image included in the image group. Replenish. Therefore, even when the toner consumption amount per unit time exceeds the replenishment capability, the opportunity to replenish the toner prior to toner consumption increases, and the occurrence of a situation where the toner becomes insufficient is suppressed. In addition, the control unit 11 prevents the toner density inside the developing device D from exceeding the upper threshold, and reduces the chance that the toner amount becomes excessive.

(3) Modification (3-1) Modification 1
In the above embodiment, the control unit 11 determines whether the measured toner density is greater than or less than the upper threshold value and the lower threshold value, so that the toner inside the developing device D is scattered and the inside of the image forming apparatus 1 Occurrence of the phenomenon of dirty recording paper was suppressed. However, the method by which the control unit 11 controls the toner density is not limited to this.
For example, it is assumed that the amount of toner that can be stored in the developing device D is sufficiently larger than the amount of toner that can be supplied from the storing device C to the developing device D within the time for forming an image. In this case, even if the control unit 11 controls the drive motor D12 within the time for forming an image and continues to supply toner from the container C to the developing unit D, the toner density inside the developing unit D becomes abnormal. It will not be high. That is, the control unit 11 does not need to determine whether the measured toner density is equal to or higher than the upper threshold value. Further, since the control unit 11 controls the driving motor D12 to continue supplying toner from the container C to the developing device D, it is determined whether the measured toner density is equal to or lower than the lower threshold value, and resumption of supply is determined. There is no need to do it. Therefore, it is not necessary to previously store one or both of the upper threshold value and the lower threshold value in the storage unit 12.

(3-2) Modification 2
In the above embodiment, the control unit 11 measures the toner density inside the developing device D by the toner density sensor D13. However, the method by which the control unit 11 measures the toner density inside the developing device D is not limited to this.
For example, the control unit 11 determines the amount of toner consumed to form an image (toner cumulative consumption amount) and the amount of toner supplied from the container C to the developing device D (toner cumulative supply amount), respectively. Then, accumulation is performed from a predetermined time such as the installation time of the image forming apparatus 1 or the reset time of the apparatus, and a difference (cumulative difference) between the accumulated values is calculated. Then, the control unit 11 may calculate a value corresponding to the toner density inside the developing device D based on the calculated cumulative difference.

(3-3) Modification 3
In the above-described embodiment, the control unit 11 determines the amount of toner consumed when an image corresponding to the image data instructed to be printed is formed on the recording sheet from the container C during the print processing according to the instruction. The developer D was replenished. However, the time when the controller 11 replenishes toner from the container C to the developing device D is not limited to this.
For example, it is assumed that the user instructs the image forming apparatus 1 to perform a plurality of print processes in order to form images of different documents. In this case, the control unit 11 replenishes the toner amount consumed by the image forming process corresponding to the subsequent print instruction from the container C to the developing device D during the print process corresponding to the preceding print instruction. It may be.

(3-4) Modification 4
In the above embodiment, the control unit 11 determines whether or not the amount of toner replenished from the container C to the developing device D has reached a predetermined toner replenishment amount based on the toner replenishment amount and the replenishment capability. Judgment was made based on the calculated replenishment time. However, the method in which the control unit 11 measures the amount of toner supplied from the container C to the developing device D is not limited to this. For example, the control unit 11 may measure the amount of replenished toner based on the number of rotations of the replenishment screw D5 provided in the adjustment chamber D1.

(3-5) Modification 5
In the above-described embodiment, the control unit 11 controls the drive motor D12 to continuously supply toner from the container C to the developing unit D as long as the upper threshold is not exceeded. However, the method in which the control unit 11 replenishes toner from the container C to the developing device D is not limited to this, and in short, replenishment that does not depend on a temporal change in the amount of color material used for the sequential development for the image group. Any method of replenishment by distribution may be used.
For example, as shown in FIG. 6 (1), the control unit 11 repeats the replenishment ON / OFF intermittently so that the toner density in the developing device D does not become lower than the reference toner density. You may control to supply toner separately. In this case, as shown in FIG. 6B, the variation in the toner density in the developing portion D is smaller than that in the case where toner is continuously supplied.
In particular, when the toner consumption per unit time is smaller than the replenishment capacity per unit time, the control unit 11 does not easily run out of toner as shown in FIG.

DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus, 11 ... Control part, 12 ... Memory | storage part, 13 ... Operation part, 14 ... Display part, 15 ... Image reading part, 16 ... Image forming part, 161 ... Photosensitive drum, 162 ... Charging part, 163 DESCRIPTION OF SYMBOLS Exposure unit, 164: Development unit, C: Container, C1: Housing, C2: Transport tool, C3: Discharge port, D: Development unit, D1: Adjustment chamber, D2: Development chamber, D3: Adjustment chamber inlet, D4 ... adjusting chamber outlet, D5 ... replenishing screw, D6 ... first stirring screw, D7 ... second stirring screw, D8 ... developing roll, D9 ... first developing chamber, D10 ... second developing chamber, D11 ... Partition, D12 ... drive motor, D13 ... toner density sensor, 165 ... transfer section, 166 ... fixing section.

Claims (5)

A color material amount calculating means for calculating a total amount of color materials used for developing an image group formed on a plurality of recording media;
A replenishing unit that replenishes an amount of color material calculated by the color material amount calculating unit to a developing unit that performs development using a developer containing a color material, and the image group is sequentially performed by the developing unit. The color material amount calculating means is a replenishment distribution in which the total amount of color material calculated by the color material amount calculating means is divided into a plurality of times without depending on temporal changes in the amount of color material used for development. A color material replenishing apparatus comprising: a replenishing unit that replenishes the developing unit with the amount of color material calculated by The replenishing unit causes the color material amount calculated by the color material amount calculating unit to equalize the color material replenishment amount per unit time, and the time from the start of development of the image group. The color material replenishing device according to claim 1, wherein the developing means is continuously replenished. The replenishing unit calculates the color material amount when the amount of color material used for development per unit time in the developing unit is smaller than the amount of color material replenished per unit time by the replenishing unit. The amount of the color material calculated by the means is compared with the case where the amount of the color material used for development per unit time in the developing means is larger than the amount of the color material replenished per unit time by the replenishing means. The color material replenishing device according to claim 1, wherein the developing unit is replenished in many times. Measuring means for measuring the amount of the color material accommodated in the developing means,
The replenishing unit stops the replenishment of the color material when the amount of the color material measured by the measuring unit becomes equal to or greater than the first threshold, and the amount of the color material measured by the measuring unit is the first amount. The color material replenishing apparatus according to claim 1 or 2, wherein the color material replenishment is resumed when the color becomes less than a second threshold value less than a threshold value of 1. The color material replenishing device according to any one of claims 1 to 4,
An image carrier for holding an image;
Charging means for charging the image carrier;
An electrostatic latent image forming unit that exposes the image carrier charged by the charging unit to form an electrostatic latent image and an electrostatic latent image formed by the electrostatic latent image forming unit Developing means for developing using the color material replenished by the material replenishing device;
Transfer means for transferring a plurality of images obtained by development of the developing means to a plurality of corresponding recording media, respectively;
Fixing means for fixing the image transferred to each recording medium by the transfer means to the recording medium,
The image forming apparatus according to claim 1, wherein the exposure unit sets a light amount when performing exposure to a light amount according to a density of a color material in a developer contained in the developing unit.

Images