JP2011095400A - Image forming device and toner supply method for developing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming device capable of preventing the occurrence of "fogging" when forming an image by using a two-component developer. <P>SOLUTION: This image forming device includes a circulation control part 51 dividing a circulation space 23 into 32 areas along the direction of circulation of the two-component developer virtually and circulating the 32 areas together with the two-component developer existent in these areas virtually when circulating the two-component developer, a supply amount deciding part 53 computing amount of toner reduction per area with respect to the reduction of amount of toner in the circulation space 23 and deciding amount of toner supply per area in accordance with the amount of toner reduction, an upper limit exceeding determining part 59 determining whether amount of toner supply exceeds an upper limit value of the amount of toner to be supplied into each area a time or not per area, and a supply control part 63 supplying toner per area by feeding the decided amount of toner to be supplied to a supply position where each area passes through while the 32 areas circulate and supplying toner by providing two chances of supply or more concerning the area where the amount of toner supply exceeds the upper limit value. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an image forming apparatus using a two-component developer composed of toner and a carrier, and a toner replenishing method for a developing device provided in the image forming apparatus.

  As an image forming apparatus using an electrophotographic system, there is an apparatus that changes a toner replenishment amount according to a density of toner remaining in a developing device and corrects a toner replenishment amount according to an area ratio of an image (for example, Patent Documents). 1).

JP 2007-304524 A

  In the formation of an image using an electrophotographic system, a phenomenon called “fogging” in which toner adheres to a white region of an image may occur.

  An object of the present invention is to provide an image forming apparatus capable of preventing “fogging” when an image is formed using a two-component developer, and a toner replenishing method for the developing apparatus.

  An image forming apparatus according to an aspect of the present invention that achieves the above object includes a developing roller, a developing device having a circulation space that contains a two-component developer containing toner to be supplied to the developing roller, and two-component development. When the agent is circulated in the circulation space, a plurality of regions virtually divided into the circulation space along the circulation direction of the two-component developer are virtually combined with the two-component developer located in those regions. A circulation control unit that circulates the toner, and a toner reduction amount for each of the plurality of regions with respect to toner reduction in the circulation space due to the two-component developer being sent from the circulation space to the developing roller, A replenishment amount determination unit that determines a toner replenishment amount for each of the plurality of areas in accordance with a toner reduction amount, and the toner replenishment amount determined by the replenishment amount determination unit is once for each of the plurality of regions. Replenish An upper limit upper limit determination unit that determines whether or not the upper limit value of the toner amount is exceeded for each of the plurality of regions, and the plurality of cycles for each circulation cycle in which the circulation control unit virtually circulates the plurality of regions. An area for supplying toner to the area is provided, and when the plurality of areas are virtually circulated, toner of the replenishment amount determined by the replenishment amount determination unit is sent to a replenishment position through which each area passes. A replenishment control unit that replenishes toner for each of the plurality of regions, and the replenishment control unit includes a region where the toner replenishment amount determined by the upper limit value excess determination unit exceeds the upper limit value. The replenishment opportunity is provided twice or more to replenish toner.

  According to this configuration, the upper limit value of the toner amount to be replenished once for each region is determined, and the toner is replenished by providing the replenishment opportunity twice or more for the region where the toner replenishment amount exceeds the upper limit value. Thereby, in a region where the amount of toner replenishment is large, the toner is replenished by providing a replenishment opportunity twice or more. Therefore, insufficient charging of the toner due to insufficient stirring of the two-component developer in that region can be prevented, so that “fogging” can be prevented. The same can be said for a toner replenishing method for a developing device according to another aspect of the present invention described later.

  In the above configuration, the image forming apparatus includes a density measuring unit that measures toner density for each of the plurality of regions, and an upper limit determining unit that determines the upper limit value according to the toner density measured by the density measuring unit. Can be further provided.

  According to this configuration, since the upper limit value is determined according to the toner density in the region, the ratio of toner and carrier can be made appropriate. Thereby, insufficient charging of the toner can be prevented, so that “fogging” can be prevented. The same can be said for a toner replenishing method for a developing device according to another aspect of the present invention described later.

  A toner replenishing method for a developing device according to another aspect of the present invention is a toner replenishing method for a developing device having a developing roller and a circulation space containing a two-component developer containing toner to be supplied to the developing roller. In the case where the two-component developer is circulated in the circulation space, a plurality of regions virtually divided into the circulation space along the circulation direction of the two-component developer are divided into the two components located in those regions. A circulation control step for virtually circulating the developer together with the developer, and a toner reduction in the circulation space due to the two-component developer being sent from the circulation space to the developing roller. A replenishment amount determination step for determining a toner replenishment amount for each of the plurality of areas according to the toner reduction amount, and the toner replenishment amount determined in the replenishment amount determination step An upper limit upper limit determination step for determining for each of the plurality of regions whether or not the upper limit value of the amount of toner to be replenished in each region of the plurality of regions is exceeded, and the plurality of regions are virtually determined by the circulation control step. The replenishment amount determining step is performed at a replenishment position through which each region passes when the plurality of regions are virtually circulated in each circulation cycle. A replenishment control step of replenishing toner for each of the plurality of areas by sending a toner of a replenishment amount determined in step (a), wherein the replenishment control step is determined by the upper limit upper limit determination step. In a region where the replenishment amount exceeds the upper limit value, the replenishment opportunity is provided twice or more to replenish toner.

  In the above method, the toner replenishing method for the developing device includes a density measuring step for measuring a toner density for each of the plurality of regions before the upper limit value determining step, and a toner density measured in the density measuring step. And an upper limit value determining step for determining the upper limit value according to.

  According to the present invention, “fogging” can be prevented when an image is formed using a two-component developer.

1 is a diagram illustrating an outline of an internal structure of an image forming apparatus according to an embodiment of the present invention. FIG. 3 is an external perspective view of a developing device provided in the image forming apparatus. It is sectional drawing which cut | disconnected the developing device shown in FIG. 2 along the A1-A2 line. FIG. 4 is a cross-sectional view of the developing device shown in FIG. 3 cut along line B1-B2. It is a figure which shows an example of the virtual several area | region divided into the circulation space of the said developing device. 4 is a flowchart illustrating a toner replenishing method for a developing device according to an embodiment of the present invention. It is a figure which shows the image pattern used when implementing the said toner replenishment method. 7 is a table for explaining toner replenishment at the first (first round) replenishment opportunity for each region when the toner density in each region measured in step ST1 of FIG. 6 is about 10%. 10 is a table for explaining toner supply at the second (second round) supply opportunity. 7 is a table for explaining toner replenishment at the first (first round) replenishment opportunity for each region when the toner density in each region measured in step ST1 of FIG. 6 is about 8%. 10 is a table for explaining toner supply at the second (second round) supply opportunity. It is a figure which shows the functional block which implement | achieves the said toner replenishment method.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram showing an outline of the internal structure of an image forming apparatus 1 according to an embodiment of the present invention. The image forming apparatus 1 can be applied to, for example, a digital multifunction machine having a color copy, a color printer, and a color facsimile function. The image forming apparatus 1 includes an apparatus main body 100 and an image reading unit 200 disposed on the apparatus main body 100.

  The image reading unit 200 reads an image (character, figure, photograph, etc.) with a CCD (Charge Coupled Device) or the like and outputs it as image data. The image reading unit 200 has a function of reading a color image. As a result, color copy and color facsimile can be transmitted.

  The apparatus main body 100 includes a sheet storage unit 110, an image forming unit 130, and a fixing unit 160.

  The paper storage unit 110 is disposed at the lowermost part of the apparatus main body 100 and includes a paper tray 111 that can store a bundle of paper P. The paper tray 111 is inserted into the apparatus main body 100 and attached. When the paper P is replenished, the paper tray 111 is pulled out from the apparatus main body 100. In the bundle of sheets P stored in the sheet tray 111, the uppermost sheet P is fed out toward the sheet conveyance path 115 by driving the pickup roller 113. The paper P is transported to the image forming unit 130 through the paper transport path 115.

  The image forming unit 130 forms a toner image on the conveyed paper P. The image forming unit 130 includes a magenta unit 133M, a cyan unit 133C, a yellow unit 133Y, and a black unit 133K, which are arranged in the order in which the toner images are transferred to the transfer belt 131. These units have the same configuration, and a magenta unit 133M will be described as an example.

  The magenta unit 133M includes a photosensitive drum 135 and an exposure device 137. Around the photosensitive drum 135, a charger 139, a developing device 141, and a cleaner 143 are disposed. The charger 139 uniformly charges the peripheral surface of the photosensitive drum 135. The exposure device 137 generates light corresponding to magenta data in image data (image data output from the image reading unit 200, image data transmitted from a personal computer, image data received by facsimile, etc.), and is uniformly charged. Irradiate the peripheral surface of the photosensitive drum 135. As a result, an electrostatic latent image corresponding to magenta data is formed on the peripheral surface of the photosensitive drum 135. In this state, by supplying magenta toner from the developing device 141 to the peripheral surface of the photosensitive drum 135, a toner image corresponding to magenta data is formed on the peripheral surface.

  The transfer belt 131 can move clockwise while being sandwiched between the photosensitive drum 135 and the primary transfer roller 145. The toner image corresponding to the magenta data is transferred from the photosensitive drum 135 to the transfer belt 131. The magenta toner remaining on the peripheral surface of the photosensitive drum 135 is removed by the cleaner 143. The above is the description of the magenta unit 133M.

  Above the magenta unit 133M, the cyan unit 133C, the yellow unit 133Y, and the black unit 133K, containers that store toner of corresponding colors, that is, a magenta toner container 147M, a cyan toner container 147C, and a yellow toner. A container for toner 147Y and a container for black toner 147K are arranged. Each color developing device 141 is supplied with toner from a corresponding container.

  As described above, the toner image corresponding to the magenta data is transferred to the transfer belt 131, and the toner image corresponding to the cyan data is transferred over the toner image. Similarly, the toner image corresponding to the yellow data and the black data are transferred. A toner image corresponding to is transferred in an overlapping manner. As a result, a color toner image is formed on the transfer belt 131. This color toner image is transferred by the secondary transfer roller 149 onto the paper P conveyed from the paper storage unit 110 described above.

  The sheet P on which the color toner image is transferred is sent to the fixing unit 160. The fixing unit 160 has a structure in which a fixing belt 165 is hung on a heating roller 161 and a fixing roller 163. The fixing belt 165 is sandwiched between the fixing roller 163 and the pressure roller 167. The paper P onto which the color toner image is transferred is sandwiched between these rollers. Accordingly, heat and pressure are applied to the color toner image and the paper P, and the color toner image is fixed to the paper P. The paper P is discharged to a paper discharge tray 169.

  Next, the developing device 141 will be described in detail. FIG. 2 is an external perspective view of the developing device 141. FIG. 3 is a cross-sectional view of the developing device 141 shown in FIG. 2 cut along the line A1-A2. The developing device 141 includes a developing roller 11, a magnet roller 13, a pumping roller 15, a first stirring screw 17, and a second stirring screw 19. These are rotatably arranged inside the developing device 141.

  The first and second stirring screws 17 and 19 are disposed in the circulation space 23. This arrangement will be described with reference to FIG. FIG. 4 is a cross-sectional view of the developing device 141 shown in FIG. 3 cut along the line B1-B2.

  The circulation space 23 includes a first stirring space 27, a second stirring space 29, and a partition plate 25 that partitions these spaces. The first and second stirring spaces 27 and 29 and the first and second stirring screws 17 and 19 extend in the same direction as the developing roller 11. A first stirring screw 17 is disposed in the first stirring space 27, and a second stirring screw 19 is disposed in the second stirring space 29, respectively.

  In the circulation space 23, a two-component developer containing toner to be supplied to the developing roller 11 is accommodated. The developing device 141 is provided with a toner replenishing port 21, and toner is replenished to the circulation space 23 from the corresponding toner container via the toner replenishing port 21. For example, in the developing device 141 of the magenta unit 133M in FIG. 1, magenta toner is supplied from the magenta toner container 147M to the circulation space 23 via the toner supply port 21.

  As the first stirring screw 17 rotates, the two-component developer in the first stirring space 27 is conveyed in the direction of arrow L along the direction in which the first stirring space 27 extends while being stirred. As the second stirring screw 19 rotates, the two-component developer in the second stirring space 29 is conveyed in the direction of arrow M opposite to the direction of arrow L while being stirred. As a result, the two-component developer circulates in the circulation space 23 while being stirred in the circulation space 23.

  When the two-component developer is stirred, the toner and the carrier are frictionally charged, and the toner and the carrier are electrostatically coupled. In this state, referring to FIG. 3, the two-component developer is sucked up from the first agitation space 27 by the pumping roller 15 incorporating the magnet, and conveyed to the magnet roller 13. In the magnet roller 13, while the carrier is attracted to the magnet roller 13, only the toner is attracted to the developing roller 11 by the electric force and attracts to the developing roller 11. The developing roller 11 is disposed to face the peripheral surface of the photosensitive drum 135 in FIG. The toner attracted to the developing roller 11 is attracted by the electrostatic latent image formed on the peripheral surface of the photosensitive drum 135 and moves to the photosensitive drum 135. As a result, the electrostatic latent image on the peripheral surface of the photosensitive drum 135 is developed, and a toner image is formed on the peripheral surface.

  By the way, the circulation space 23 is virtually divided into a plurality of regions along the circulation direction of the two-component developer. By sending the two-component developer from the circulation space 23 to the developing roller 11, the two-component developer is lost from the circulation space 23. As a result of the toner reduction in the circulation space 23, the toner reduction amount is managed for each of a plurality of areas. FIG. 5 is a diagram illustrating an example of a plurality of virtual regions divided into the circulation space 23. In this example, the area is divided into 32 areas R1 to R32. The number after the symbol R may be omitted. For example, if it is not necessary to distinguish each of the regions R1 to R32, the region R may be described.

  The 32 regions R are arranged along the circulation direction (arrows L and M) of the two-component developer. In FIG. 5, 16 regions R <b> 1 to R <b> 16 are located in the first stirring space 27, and 16 regions R <b> 17 to R <b> 32 are located in the second stirring space 29.

  Virtually dividing into a plurality of areas does not mean that the areas R1 to R32 are physically divided by a partition or the like. In the program for controlling the operation of the image forming apparatus 1, this means that the circulation space 23 is divided into regions R1 to R32. In the above program, when the two-component developer is circulated, 32 regions R are virtually circulated together with the two-component developer located in those regions R.

  The two-component developer is sent from the first stirring space 27 in the circulation space 23 to the developing roller 11. In other words, the two-component developer is sent to the developing roller 11 from the region (regions R1 to R16 in FIG. 5) located in the first stirring space 27. The amount of the two-component developer supplied from each region R, that is, the amount of toner varies depending on the image data on which image formation is based.

  Accordingly, since the toner reduction amount is different in each of the regions R1 to R16, the toner reduction amount is calculated for each of these regions R. Then, the toner replenishment amount is determined for each region R according to the respective toner reduction amounts in the regions R1 to R16. Opportunities for supplying toner to the region R are provided for each circulation cycle in which the region R is virtually circulated. When the two-component developer is circulated (regions R1 to R32 are virtually circulated), the determined replenishment amount of toner is sent to the replenishment position through which each region R passes, so that the region R1 Toner is replenished for each region R16. The same applies when the regions R17 to R32 are located in the first stirring region 27.

  For example, when the toner is reduced by 0.2% in the region R6, when the two-component developer is circulated (the regions R1 to R32 are virtually circulated), 0.2% from the toner supply port 21. Is supplied to the region R6.

  However, when a large amount of toner is reduced in a certain region R, a large amount of toner is supplied to the region R. For this reason, toner is insufficiently charged due to insufficient stirring of the two-component developer, and “fogging” may occur.

  In the present embodiment, an upper limit value of the toner amount to be replenished once for each region R is determined. In the region R where the toner replenishment amount exceeds the upper limit value, “fogging” is prevented by replenishing the toner by providing replenishment opportunities two or more times. A method for supplying toner to the developing device 141 according to the present embodiment will be described with reference to FIGS. 4, 5, and 6. FIG. 6 is a flowchart illustrating the above method.

  First, the first and second stirring screws 17 and 19 shown in FIG. 4 are rotated to circulate the circulation space 23 while stirring the two-component developer. By stirring the two-component developer, the toner and the carrier are triboelectrically charged and electrostatically coupled. Due to the circulation of the two-component developer, the region R1 to the region R32 are virtually circulated together with the two-component developer located in the region R (circulation control step).

  As shown in FIG. 5, a density sensor 31 for measuring the toner density is arranged in the circulation space 23. In the circulation control step, every time each region R passes the location where the density sensor 31 is disposed, the toner concentration in that region R is measured (step ST1: density measurement step).

  For example, a magnetic permeability sensor can be used as the concentration sensor 31. The output of the magnetic permeability sensor changes according to the carrier concentration. If the carrier concentration is high, that is, if the toner concentration is low, the output becomes large. If the carrier concentration is low, that is, if the toner concentration is high, the output is small.

  It is determined whether the toner density measured in step ST1 is a value that requires toner replenishment (step ST3). If it is not necessary to replenish toner (No in step ST3), the end is reached. When it is necessary to replenish toner (Yes in step ST3), the toner reduction amount of the two-component developer is calculated for each of the regions R1 to R32 (step ST5). The toner reduction amount for each region R can be obtained from the printing rate of the image formed on the paper P. It can also be obtained from the dot count of the image. The amount of toner decrease in each of the regions R1 to R32 is set as a toner replenishment amount (replenishment amount determination step).

  In accordance with the toner density measured in step ST1, an upper limit value of the toner amount to be replenished for each region R is determined (step ST7: upper limit value determining step). For example, if the toner concentration in the regions R1 to R32 is about 10%, the upper limit value is equivalent to 0.3%, and if the toner concentration is about 8%, the upper limit value is equivalent to 0.4%. The toner amount. If the toner density is between 8% and 10%, the upper limit is set between 0.3 and 0.4. For example, if the toner density is about 9%, the upper limit value is set to a toner amount corresponding to 0.35%.

  It is determined for each of the regions R1 to R32 whether the toner reduction amount (toner supply amount) calculated in step ST5 exceeds the upper limit value determined in step ST7 (step ST9: upper limit value excess determination step).

  For the region R in which the toner reduction amount (toner replenishment amount) is less than or equal to the upper limit value (No in step ST9), a replenishment opportunity is provided once. When 32 regions R are virtually circulated in the circulation control step, all of the toner replenishment amount is replenished in the first round (step ST11: replenishment control step). On the other hand, if the toner decrease amount (toner replenishment amount) exceeds the upper limit value, the toner is replenished with two or more replenishment opportunities (step ST13: replenishment control step). The adjustment of the toner replenishment amount can be realized by adjusting the rotation speed of feeders provided in the respective color containers 147M, 147C, 147Y, and 147K shown in FIG.

  The toner replenishing method according to the present embodiment was performed using an example in which an image having the pattern shown in FIG. The development data for this image formation was as follows.

Two-component developer: 320 g
Number of regions R: 32 Weight of two-component developer per region R: 10 g
Toner weight per region R: 1 g
Print data: rectangular black pattern 41 with horizontal H of 2 cm and vertical V of 8 cm
Rectangular black pattern 43 with horizontal H of 2 cm and vertical V of 20 cm
The toner of region R6 was used for forming the black pattern 41, and the toner of region R14 was used for forming the black pattern 43.

  8 and 9 are tables for explaining toner replenishment to the regions R1 to R32 when the toner concentration in each region R measured in step ST1 is about 10%. FIG. 8 shows toner supply at the first (first round) supply opportunity, and FIG. 9 shows toner supply at the second (second round) supply opportunity. The upper limit value was a toner amount corresponding to 0.3%.

  On the other hand, FIGS. 10 and 11 are tables for explaining toner replenishment to the regions R1 to R32 when the toner concentration in each region R measured in step ST1 is about 8%. FIG. 10 shows toner supply at the first (first round) supply opportunity, and FIG. 11 shows toner supply at the second (second round) supply opportunity. When the toner concentration is about 8%, the upper limit is set to 0.4, which is higher than when the toner concentration is about 10%. The upper limit of the lower toner density is increased because the lower toner density has a relatively high carrier density, and even if a large amount of toner is replenished, there will be no shortage of frictional charging between the toner and the carrier. It is.

  In region R6, the toner replenishment amount (toner decrease amount) was 0.2, and in region R14, the toner replenishment amount (toner decrease amount) was 0.5. In the region R other than the region R6 and the region R14, the toner is not decreased, so the toner is not replenished. For these regions R, the description of data is omitted except for the toner density.

  When the toner density in each region R is about 8%, the upper limit is set to 0.4, and when it is about 10%, the upper limit is set to 0.3. In any case, the toner replenishment opportunity was provided twice for the region R14 where the toner replenishment amount is large. As a result, “fogging” could be prevented. In contrast, when the toner concentration in each region R is about 8%, the upper limit value is 0.5, and when the toner concentration is about 10%, the upper limit value is 0.4. “Cover” sometimes occurred.

  In this embodiment, the upper limit value is changed according to the toner concentration. For this reason, if the amount of toner replenishment to the region R14 is 0.35, for example, the number of replenishment opportunities is once when the toner density is about 8% and twice when the toner density is about 10%.

  As described above, according to the present embodiment, the upper limit value of the toner amount to be replenished for each region R in the regions R1 to R32 is determined, and the region R in which the toner replenishment amount exceeds the upper limit value is determined. Replenish the toner with more than one replenishment opportunity. As a result, in the region R where the toner replenishment amount is large, the toner is replenished by providing replenishment opportunities twice or more. Therefore, in the region R, insufficient charging of the toner due to insufficient stirring of the two-component developer can be prevented, so that “fogging” can be prevented. Furthermore, in this embodiment, since the upper limit value is determined according to the toner concentration, the ratio between the toner and the carrier can be made appropriate. Also from this point, it is possible to prevent the toner from being insufficiently charged, thereby preventing “fogging”.

  For the region R where the toner supply amount exceeds the upper limit value, various modes can be adopted as modes for supplying toner by providing a supply opportunity twice or more. For example, when the toner amount is reduced by 0.5% in a certain region R and the toner amount corresponding to 0.5% is supplied, the upper limit value is assumed to be the toner amount corresponding to 0.3%.

  (1) The toner amount corresponding to the upper limit value is replenished at the first time, and the remaining toner amount is replenished at the second time. In this example, the toner amount corresponding to 0.3% is replenished in the first time, and the toner amount corresponding to 0.2% is replenished in the second time.

  (2) Replenish a toner amount less than the upper limit in both the first time and the second time. In this example, a toner amount corresponding to, for example, 0.25% is supplied for the first time, and a toner amount corresponding to 0.25% is supplied for the second time.

  (3) Supply toner in three or more times. In this example, for example, a toner amount corresponding to 0.2% is replenished at the first time, a toner amount corresponding to 0.2% is replenished at the second time, and a toner amount corresponding to 0.1% is replenished at the third time. To do.

  Although the example in which the upper limit value is determined according to the toner density has been described, the upper limit value can be set to one value regardless of the toner density. In this case, step ST7 is omitted, and in step ST9, it is determined for each of the regions R1 to R32 whether the toner reduction amount (toner replenishment amount) calculated in step ST5 exceeds a predetermined upper limit value.

  Further, in the region R where the toner replenishment amount exceeds the upper limit value, after the first (first round) replenishment opportunity, the two-component developer is sent from the circulation space 23 to the developing roller 11, thereby reducing the toner in that region R. When a new toner occurs, the toner replenishment amount may be added and the toner replenishment may be executed at the replenishment opportunity after the next (next round).

  According to this configuration, since the newly generated toner reduction amount is added and toner supply from the next time is executed, it is possible to reduce the number of toner supply times in the region R where the toner reduction amount exceeds the upper limit value. .

  Finally, functional blocks for realizing the toner replenishing method for the developing device according to the present embodiment will be described. FIG. 12 is a diagram showing this functional block. The functional blocks described below can be realized by an MPU (Micro Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), or the like that controls the image forming apparatus 1.

  The circulation control unit 51 controls the circulation space 23 to circulate while stirring the two-component developer by the first and second stirring screws 17 and 19 disposed in the developing device 141. The circulation space 23 is virtually divided into 32 regions R along the circulation direction of the two-component developer (arrows M and L in FIG. 5). When the two-component developer is circulated, the circulation control unit 51 virtually circulates the 32 regions R together with the two-component developer located in those regions R.

  The replenishment amount determination unit 53 calculates the toner reduction amount for each of the 32 regions R with respect to the toner reduction in the circulation space 23 due to the two-component developer being sent from the circulation space 23 to the developing roller 11, and the toner reduction amount. Accordingly, the toner supply amount is determined for each of the 32 regions R.

  The replenishment amount determination unit 53 includes a printing rate calculation unit 55 that calculates the printing rate of an image formed on the paper P. The replenishment amount determination unit 53 obtains the toner reduction amount for each of the 32 regions R from the printing rate calculated by the printing rate calculation unit 55. The amount of toner reduction in each of the 32 regions R is used as the amount of toner replenished to each region R. In this embodiment, the toner replenishment amount is matched with the toner decrease amount, but a mode in which they do not match is also possible.

  The density measuring unit 57 includes the density sensor 31. The density sensor 31 outputs an output that correlates with the toner density in each of the 32 areas R. The density measuring unit 57 measures the toner density for each of the 32 regions R based on the output from the density sensor 31.

  The upper limit value excess determination unit 59 determines whether the toner supply amount determined by the supply amount determination unit 53 exceeds the upper limit value of the toner amount to be supplied to each region R of the 32 regions R. The determination is made for each region R. The upper limit excess determination unit 59 includes an upper limit determination unit 61. The upper limit determination unit 61 determines an upper limit value according to the toner density measured by the density measurement unit 57.

  The replenishment control unit 63 provides an opportunity to replenish toner to the region R for each circulation cycle in which the circulation control unit 51 virtually circulates the region R. The replenishment control unit 63 sends toner of the replenishment amount determined by the replenishment amount determination unit 53 to the replenishment position through which each region R passes when the circulation control unit 51 virtually circulates the 32 regions R. The toner is replenished every 32 areas R. The supply control unit 63 includes a supply amount distribution unit 65 and a feeder rotation control unit 67.

  The supply amount distribution unit 65 determines how many replenishment opportunities are provided for the region R in which the toner supply amount determined by the upper limit excess determination unit 59 exceeds the upper limit value, and the amount of toner to be supplied each time. The feeder rotation control unit 67 adjusts the toner replenishment amount to the circulation space 23 by adjusting the rotation speed of the feeder 69 provided in each color toner container 147M, 147C, 147Y, 147K. As a result, the amount of toner supplied to each region R is controlled.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 11 Developing roller 13 Magnet roller 15 Pumping roller 17 1st stirring screw 19 2nd stirring screw 21 Toner replenishment port 23 Circulation space 25 Partition plate 27 1st stirring space 29 2nd stirring space 31 Density sensor 51 Circulation Control Unit 53 Replenishment Amount Determination Unit 55 Print Rate Calculation Unit 57 Density Measurement Unit 59 Upper Limit Exceeding Determination Unit 61 Upper Limit Determination Unit 63 Replenishment Control Unit 65 Replenishment Amount Distribution Unit 67 Feeder Rotation Control Unit 69 Feeder 141 Developing Device R ( R1-R32) region

Claims (4)

A developing device having a developing roller and a circulation space for storing a two-component developer containing toner to be supplied to the developing roller;
When the two-component developer is circulated in the circulation space, a plurality of regions virtually divided into the circulation space along the circulation direction of the two-component developer, and the two-component developer located in those regions; A circulation control unit that virtually circulates together,
With respect to toner reduction in the circulation space due to the two-component developer being sent from the circulation space to the developing roller, a toner reduction amount is calculated for each of the plurality of regions, and the plurality of the plurality of developer is calculated according to the toner reduction amount. A replenishment amount determining unit for determining a toner replenishment amount for each region;
Exceeding an upper limit value for determining, for each of the plurality of regions, whether the toner supply amount determined by the replenishment amount determining unit exceeds the upper limit value of the toner amount to be supplied to each of the plurality of regions at a time. A determination unit;
The circulation control unit is provided with a toner replenishment opportunity for each of the plurality of regions for each circulation cycle in which the plurality of regions are virtually circulated, and each time when the plurality of regions are circulated virtually A replenishment control unit that replenishes toner for each of the plurality of regions by sending toner of a replenishment amount determined by the replenishment amount determination unit to a replenishment position through which the region passes;
The replenishment control unit
An image forming apparatus, wherein the toner supply amount is supplied by providing the supply opportunity twice or more in an area where the toner supply amount determined by the upper limit excess determination unit exceeds the upper limit value. The image forming apparatus includes:
A density measuring unit that measures toner density for each of the plurality of areas;
The image forming apparatus according to claim 1, further comprising: an upper limit value determining unit that determines the upper limit value according to a toner density measured by the density measuring unit. A toner replenishing method for a developing device having a developing roller and a circulation space containing a two-component developer containing toner to be supplied to the developing roller,
When the two-component developer is circulated in the circulation space, a plurality of regions virtually divided into the circulation space along the circulation direction of the two-component developer, and the two-component developer located in those regions; A circulation control step that virtually circulates together,
With respect to toner reduction in the circulation space due to the two-component developer being sent from the circulation space to the developing roller, a toner reduction amount is calculated for each of the plurality of regions, and the plurality of the plurality of developer is calculated according to the toner reduction amount. A replenishment amount determination step for determining a toner replenishment amount for each region;
Exceeding an upper limit value for determining, for each of the plurality of areas, whether the toner supply amount determined in the replenishment amount determination step exceeds an upper limit value of the toner amount to be supplied to each of the plurality of areas at a time. A determination step;
In the circulation control step, an opportunity for supplying toner to the plurality of regions is provided for each circulation cycle in which the plurality of regions are virtually circulated, and each time when the plurality of regions are virtually circulated A replenishment control step of replenishing toner for each of the plurality of regions by sending toner of the replenishment amount determined in the replenishment amount determination step to a replenishment position through which the region passes,
The replenishment control step includes
A toner replenishing method for a developing device, wherein toner is replenished by providing the replenishment opportunity twice or more in a region where the toner replenishment amount determined in the upper limit exceeded excess determination step exceeds the upper limit. The toner replenishing method to the developing device is
Before the upper limit exceeded determination step,
A density measuring step for measuring toner density for each of the plurality of areas;
4. The toner replenishing method for a developing device according to claim 3, further comprising an upper limit determining step for determining the upper limit according to the toner density measured in the density measuring step.

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