Developing apparatus, image forming apparatus, developing apparatus adjustment method, and developing apparatus adjustment program

Abstract

This suppresses the degradation of the quality of the toner image developed on the image carrier. [Solution] A developing apparatus for developing an electrostatic latent image on an image carrier with a developer supported on a developing roller comprises: a first circulation tank Sp1 having a supply port for supplying a portion of the developer to the developing roller while conveying the developer in the conveying direction; a second circulation tank Sp2 for conveying the developer conveyed from the first circulation tank Sp1 through a first opening 209 to the first circulation tank Sp1 through a second opening 207; and a detection unit 300Y for detecting information related to the speed of the developer being conveyed in the circulation path formed by the first circulation tank Sp1 and the second circulation tank Sp2.

Description

Technical Field

[0001] The present invention relates to a developing device, an image forming apparatus, a developing device adjustment method, and a developing device adjustment program. In particular, the present invention relates to a developing device used in an image forming apparatus that forms an image using toner, an image forming apparatus including the developing device, a developing device adjustment method for adjusting the developing device, and a developing device adjustment program executed by a computer that controls the developing device.

Background Art

[0002] An image forming apparatus typified by an MFP (Multi Function Peripheral) frictionally charges a developer composed of toner and a carrier by stirring the developer in a developing device, and forms a toner image on a photosensitive drum from a developing roller by imparting charges to toner particles.

[0003] While the developing device conveys the developer along a circulation path, the developing roller holds the developer, and toner among the developer held by the developing roller is supplied to the photosensitive drum. The fluidity of the developer changes while the developer is conveyed along the circulation path. Techniques corresponding to changes in the fluidity of the developer are known.

[0004] For example, Japanese Patent Publication No. 2009-36786 describes a developing apparatus comprising: a housing divided internally into a first storage chamber and a second storage chamber; a developer carrier disposed in the first storage chamber so as to face an image carrier; a first stirring and conveying member disposed in the first storage chamber substantially parallel to the developer carrier and stirring and conveying the developer in the thrust direction of the developer carrier; and a second stirring and conveying member disposed in the second storage chamber substantially parallel to the first stirring and conveying member and stirring and conveying the developer in the opposite direction to the first stirring and conveying member, wherein the developer is circulated between the first and second storage chambers by the first and second stirring and conveying members, and the developing apparatus is characterized by being provided with a detection means for detecting the accumulation of developer in the housing, and controlling the rotation direction or rotation speed of the first and second stirring and conveying members based on the detection result of the detection means. This detection means consists of a first piezoelectric sensor that detects the pressure when the developer circulates in a predetermined direction, and a second piezoelectric sensor that detects the pressure when the developer circulates in the opposite direction. When a pressure above a predetermined level is detected, the rotation speed is controlled.

[0005] A portion of the developer carried on the developing roller is recovered and returned to the circulation path. At the confluence region where the developer returned from the developing roller merges with the developer transported in the circulation path, the volume of developer tends to be higher than upstream of the confluence region. In the circulation path, the developer may flow upstream from the confluence region in the opposite direction to the transport direction. The developer contains a carrier and toner. Since the developer returned from the developing roller to the circulation path has a reduced toner concentration, the developer with the lower toner concentration may flow in the reverse direction in the transport path. If the confluence region is located downstream of the developing roller, the end of the developing roller may be supplied with developer with a lower toner concentration. In this case, a problem occurs where the image density is lower in the part corresponding to the end of the developing roller. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2009-36786 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] One of the objectives of this invention is to provide a developing apparatus that suppresses the deterioration of the quality of the toner image developed on the image carrier.

[0008] Another object of this invention is to provide an image forming apparatus that suppresses the degradation of image quality.

[0009] Another object of this invention is to provide a developing apparatus adjustment method that suppresses the deterioration of the quality of the toner image developed on the image carrier.

[0010] Another object of this invention is to provide a developing apparatus adjustment program that suppresses the deterioration of the quality of the toner image developed on the image carrier. [Means for solving the problem]

[0011] According to one aspect of this invention, a developing apparatus is a developing apparatus for developing an electrostatic latent image on an image carrier with a developer supported on a developing roller, comprising: a first circulation tank having a supply port for supplying a portion of the developer to the developing roller while conveying the developer in the conveying direction; a second circulation tank for conveying the developer conveyed from the first circulation tank through a first opening to the first circulation tank through a second opening; and a detection unit for detecting information related to the speed of the developer conveyed in a circulation path formed by the first circulation tank and the second circulation tank.

[0012] According to another aspect of this invention, the image forming apparatus comprises the above-described developing apparatus and a transfer unit that transfers the toner image developed on the image carrier with the developer to a recording medium.

[0013] According to another aspect of this invention, a developing apparatus adjustment method is a developing apparatus for developing an electrostatic latent image on an image carrier with a developer supported on a developing roller, wherein the developing apparatus comprises a first circulation tank having a supply port for supplying a portion of the developer to the developing roller while conveying the developer in a conveying direction, a second circulation tank for conveying the developer conveyed from the first circulation tank through a first opening to the first circulation tank through a second opening, and a detection unit for detecting information relating to the speed of the developer conveyed in a circulation path formed by the first circulation tank and the second circulation tank, and includes a conveying efficiency improvement step for improving the conveying efficiency of the developer downstream of the detection unit in accordance with predetermined conditions that the information relating to the speed of the developer detected by the detection unit satisfies.

[0014] According to another aspect of this invention, the developing apparatus adjustment program is a developing apparatus adjustment program executed by a computer that controls a developing apparatus for developing an electrostatic latent image on an image carrier with a developer supported on a developing roller, wherein the developing apparatus comprises a first circulation tank having a supply port for supplying a portion of the developer to the developing roller while transporting the developer in the transport direction, a second circulation tank for transporting the developer transported from the first circulation tank through a first opening to the first circulation tank through a second opening, and a detection unit for detecting information relating to the speed of the developer transported in a circulation path formed by the first circulation tank and the second circulation tank, and the computer is made to execute a transport efficiency improvement step to improve the transport efficiency of the developer downstream of the detection unit, in response to the information relating to the speed of the developer detected by the detection unit satisfying predetermined conditions. [Brief explanation of the drawing]

[0015] [Figure 1] This is a schematic front view of an image forming system in one embodiment of the present invention. [Figure 2] This diagram schematically shows the internal configuration of an image forming apparatus. [Figure 3] This is an XZ cross-sectional view of the developing apparatus. [Figure 4] This is a cross-sectional view along line AA in Figure 3. [Figure 5] It is an X-Y cross-sectional view with an enlarged vicinity of the recovery port of the developing device. [Figure 6] It is a cross-sectional view taken along the line C-C of FIG. 5. [Figure 7] It is a view showing the addition of a detection unit to the cross-sectional view of FIG. 3. [Figure 8] It is a perspective view of the paddle. [Figure 9] It is a front view of the paddle. [Figure 10] It is a view for explaining the first inclined surface and the second inclined surface of the blade part. [Figure 11] It is a block diagram showing an example of the main circuit included in the image forming apparatus. [Figure 12] It is a block diagram showing an example of the functions of the CPU included in the image forming apparatus. [Figure 13] It is a flowchart showing an example of the flow of the developing device adjustment process. [Figure 14] It is a view showing an example of experimental data. [Figure 15] It is an X-Z cross-sectional view of the developing device in the first modification example. [Figure 16] It is an X-Y cross-sectional view with an enlarged vicinity of the recovery port of the developing device in the first modification example. [Figure 17] It is a perspective view of a part of the detection unit. [Figure 18] It is a plan view showing another part of the detection unit enlarged. [Figure 19] It is a view showing an example of experimental data in the first modification example. [Figure 20] It is an X-Z cross-sectional view of the developing device in the second modification example. [Figure 21] It is an X-Y cross-sectional view with an enlarged vicinity of the recovery port of the developing device in the second modification example. [Figure 22] It is an X-Z cross-sectional view of the developing device in the third modification example. [Figure 23] It is a Y-Z cross-sectional view of the vicinity of the detection unit of the developing device in the third modification example. [Figure 24] It is an X-Z cross-sectional view of the developing device in the fourth modification example. [Figure 25] This is a YZ cross-sectional view of the developing apparatus in the fifth modified example. [Figure 26] This is a YZ cross-sectional view of the developing apparatus in the sixth modified example. [Figure 27] This is an XZ cross-sectional view of the developing apparatus in the seventh modified example. [Figure 28] This is a YZ cross-sectional view of the vicinity of the detection unit of the developer in the seventh modified example. [Modes for carrying out the invention]

[0016] Embodiments of the present invention will be described below with reference to the drawings. In the following description, identical parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed descriptions of them will not be repeated.

[0017] Figure 1 is a schematic front view of an image forming system in one embodiment of the present invention. Some of the drawings from Figure 1 onward are accompanied by arrows indicating the mutually orthogonal X, Y, and Z directions to clarify the positional relationships. The X and Y directions are mutually orthogonal in the horizontal plane, and the Z direction corresponds to the vertical direction. In the following description, in the X direction, the direction in which the arrow points is referred to as the right, and the opposite direction is referred to as the left. Similarly, in the Y direction, the direction in which the arrow points is referred to as the front, and the opposite direction is referred to as the back.

[0018] Referring to Figure 1, the image forming system 1 includes a paper feeder 2, an image forming apparatus 3, an image inspection apparatus 4, and a post-processing apparatus 5. The post-processing apparatus 5 includes a processing apparatus 6, a transport apparatus 7, a cutting apparatus 8, and a paper output tray 9. The paper feeder 2, image forming apparatus 3, image inspection apparatus 4, processing apparatus 6, transport apparatus 7, cutting apparatus 8, and paper output tray 9 are arranged in this order from the paper feeder 2 to the left.

[0019] The paper feeder 2 has multiple types of paper feed cassettes and supplies recording media contained in one of the multiple paper feed cassettes to the image forming apparatus 3. The image forming apparatus 3 forms an image on the recording media supplied from the paper feeder 2 and outputs the paper with the formed image to the image inspection apparatus 4. The image inspection apparatus 4 inspects the image formed on the recording media and transports the recording media to the processing apparatus 6. Recording media with images in which defects are detected by the inspection by the image inspection apparatus 4 are discharged into a predetermined output tray.

[0020] The processing device 6 performs punching and folding on multiple sheets of paper discharged from the image inspection device 4. Punching is the process of punching holes in multiple sheets of paper. Folding is the process of folding the booklet based on the center. The processing device 6 forms one booklet BK each time a predetermined number of sheets of paper are discharged from the image inspection device 4. In this embodiment, booklet BK refers to a stack of a predetermined number of sheets of paper. Note that booklet BK includes a stack of single sheets of paper.

[0021] The conveying device 7 has a built-in conveying belt and conveys the booklets BK discharged from the processing device 6 to the cutting device 8. The cutting device 8 performs flattening and cutting on the booklets BK received from the conveying device 7. In this example, the flattening process is the process of flattening the spine of the booklets BK, and the cutting process is the process of cutting the fore-edge of the booklets BK. The output tray 9 collects multiple booklets BK discharged from the cutting device 8.

[0022] Figure 2 is a schematic diagram showing the internal configuration of the image forming apparatus. Referring to Figure 2, the image forming apparatus 3 includes image forming units 20Y, 20M, 20C, and 20K, which correspond to yellow, magenta, cyan, and black, respectively. Here, "Y", "M", "C", and "K" represent yellow, magenta, cyan, and black, respectively. Printing data for yellow, magenta, cyan, and black is input to the image forming units 20Y, 20M, 20C, and 20K, respectively. Since the image forming units 20Y, 20M, 20C, and 20K only differ in the color of the toner they handle, we will describe the image forming unit 20Y, which is used to form a yellow image, here.

[0023] The image forming unit 20Y includes a developing device 21Y, a photosensitive drum 23Y which is an image carrier, a charging roller 22Y, an exposure device 24Y, a primary transfer roller 25Y, a toner bottle 41Y, and a toner hopper 42Y.

[0024] The toner bottle 41Y, toner hopper 42Y, and developer unit 21Y are arranged in this order along the path through which toner is transported. The toner hopper 42Y is positioned directly in front of the developer unit 21Y. Toner is supplied from the toner hopper 42Y to the developer unit 21Y via the toner transport path.

[0025] The developing device 21Y includes a first developing roller 51Y and a second developing roller 53Y (see Figure 3), which will be described later. The first developing roller 51Y and the second developing roller 53Y have built-in magnetic rollers that hold the charged developer stored in the developing device 21Y by magnetic force. The photoreceptor drum 23Y has a cylindrical shape, and the charging roller 22Y, exposure device 24Y, first developing roller 51Y, second developing roller 53Y, and primary transfer roller 25Y are arranged in order around the photoreceptor drum 23Y along the rotation direction of the photoreceptor drum 23Y.

[0026] The photoreceptor drum 23Y is charged on its surface by the charging roller 22Y, and then irradiated with laser light emitted by the exposure device 24Y. The exposure device 24Y exposes the image-corresponding portion of the surface of the photoreceptor drum 23Y to form an electrostatic latent image. This forms an electrostatic latent image on the photoreceptor drum 23Y. Subsequently, the developing device 21Y develops the electrostatic latent image formed on the photoreceptor drum 23Y with toner. Specifically, the toner contained in the developer held by the first developing roller 51Y and the second developing roller 53Y is placed on the electrostatic latent image formed on the photoreceptor drum 23Y by the action of an electric field, thereby forming a toner image on the photoreceptor drum 23Y. The toner image formed on the photoreceptor drum 23Y is transferred onto the intermediate transfer belt 27, which is an image carrier, by the action of an electric field using the primary transfer roller 25Y.

[0027] The intermediate transfer belt 27 is suspended by a drive roller R1 and a driven roller R2 to prevent slack. When the drive roller R1 rotates clockwise in the figure, the intermediate transfer belt 27 rotates clockwise in the figure at a predetermined speed. As the intermediate transfer belt 27 rotates, the driven roller R2 rotates clockwise.

[0028] As a result, the image forming units 20Y, 20M, 20C, and 20K transfer toner images onto the intermediate transfer belt 27 in this order. The timing at which each of the image forming units 20Y, 20M, 20C, and 20K transfers toner images onto the intermediate transfer belt 27 is adjusted by detecting reference marks attached to the intermediate transfer belt 27. As a result, yellow, magenta, cyan, and black toner images are superimposed on the intermediate transfer belt 27.

[0029] The receiving roller R5, timing roller 29, secondary transfer roller R3, fixing roller pair R4, and discharge roller R6 are arranged in this order along the transport path P1 in the transport direction. The receiving roller R5 receives the paper transported from the paper feed device 2 and transports the paper toward the timing roller 29. The timing roller 29 transports the paper toward the secondary transfer roller R3 at a predetermined timing.

[0030] The secondary transfer roller R3 is positioned opposite the drive roller R1. An electric field force is generated by the secondary transfer roller R3 between the secondary transfer roller R3 and the drive roller R1. As a result, when the paper being transported along the transport path P1 passes through the nip between the secondary transfer roller R3 and the drive roller R1, the toner image formed on the intermediate transfer belt 27 is transferred to the first surface of the paper by the action of the electric field force. The timing roller 29 starts transporting the paper in accordance with the timing when the toner image carried on the intermediate transfer belt 27 reaches the nip. The paper with the transferred toner image is transported to the fuser roller pair R4. The fuser roller pair R4 heats and pressurizes the paper as it passes between them. This melts the toner and fixes it to the first surface of the paper.

[0031] A switching claw 33 is positioned on the transport path P1 between the fuser roller pair R4 and the discharge roller R6. The image forming apparatus 3 includes a reversal mechanism 30 below the transport path P1. The reversal mechanism 30 includes a reversal path P2, a reversal roller R7 positioned in the reversal path P2, and a retractable tray 34. The switching claw 33 switches the direction of paper travel to either the transport path P1 or the reversal path P2. When the switching claw 33 has switched the direction of paper travel to the transport path P1, the paper transported by the fuser roller pair R4 travels along the transport path P1 and is received by the discharge roller R6. The discharge roller R6 receives the paper transported by the fuser roller pair R4 and transports the paper. The paper transported by the discharge roller R6 travels along the transport path P1 and is supplied to the image inspection apparatus 4.

[0032] When the switching claw 33 switches the direction of paper travel to the reverse path P2, the paper transported by the fuser roller pair R4 travels along the reverse path P2. The reverse path P2 includes a retraction path 31 and a resupply path 32. The retraction path 31 is a path from the upstream position of the switching claw 33 on the transport path P1 to the retraction tray 34. The resupply path 32 is a path from the retraction tray 34 to the upstream position of the receiving roller R5 on the transport path P1.

[0033] When the switching claw 33 switches the paper's direction of travel to the reversal path P2, the paper being transported by the fixing roller pair R4 enters the retraction path 31. Multiple rollers are arranged in the retraction path 31, and these multiple rollers transport the paper. The paper transported by the multiple rollers in the retraction path 31 moves along the retraction path 31 and is received by the reversal roller R7.

[0034] The reversing roller R7 rotates in the forward direction to transport the paper toward the retraction tray 34. After transporting a predetermined amount of paper to the retraction tray 34, the reversing roller R7 reverses its direction of rotation and rotates in the reverse direction. As the reversing roller R7 rotates in the reverse direction, the paper that has been partially placed in the retraction tray 34 is transported in the opposite direction to the direction it was previously transported and enters the resupply path 32. Multiple rollers are arranged in the resupply path 32, and these multiple rollers transport the paper. The paper transported by the multiple rollers is transported along the resupply path 32 and enters the transport path P1.

[0035] The receiving roller R5 receives the paper being transported along the resupply path 32 by multiple rollers in the resupply path 32 and transports the paper toward the timing roller 29. The upward-facing side of the paper received by the receiving roller R5 after passing through the resupply path 32 is the second side opposite to the first side that faced upward while the paper was being supplied from the paper feed device 2 and transported along the transport path P1. Therefore, an image is formed on the second side of the paper while it is being transported along the transport path P1 by the receiving roller R5 as it is being transported along the resupply path 32.

[0036] When forming a full-color image, the image forming apparatus 3 drives all of the image forming units 20Y, 20M, 20C, and 20K. When forming a monochrome image, the image forming apparatus 3 drives one of the image forming units 20Y, 20M, 20C, and 20K. It is also possible to form an image by combining two or more of the image forming units 20Y, 20M, 20C, and 20K.

[0037] Figure 3 is a cross-sectional view of the developing apparatus along the XZ line. Figure 4 is a cross-sectional view along the AA line of Figure 3. Figure 3 is a cross-sectional view along the BB line of Figure 4. Referring to Figures 3 and 4, the developing apparatus 21Y forms a toner image on the photoreceptor drum 23Y using a developer consisting of a carrier and toner. The developing apparatus 21Y is supplied with developer from the toner hopper 42Y. The developing apparatus 21Y includes a case 200Y, a first screw 201Y, a second screw 203Y, a first developing roller 51Y, a second developing roller 53Y, a recovery roller 55Y, and a recovery screw 57Y. Note that in Figure 4, the second developing roller 53Y, the recovery roller 55Y, and the recovery screw 57Y are omitted.

[0038] Case 200Y is a housing that contains the developer, the first screw 201Y, the second screw 203Y, the first developing roller 51Y, the second developing roller 53Y, the recovery roller 55Y, and the recovery screw 57Y. The first screw 201Y, the second screw 203Y, the first developing roller 51Y, the second developing roller 53Y, the recovery roller 55Y, and the recovery screw 57Y are each installed in parallel within Case 200Y. The direction in which the first screw 201Y, the second screw 203Y, the first developing roller 51Y, the second developing roller 53Y, the recovery roller 55Y, and the recovery screw 57Y extend is the Y direction. The first screw 201Y, the second screw 203Y, the first developing roller 51Y, the second developing roller 53Y, the recovery roller 55Y, and the recovery screw 57Y are pivotally supported in Case 200Y in a rotatable manner. The first screw 201Y, the second screw 203Y, the first developing roller 51Y, the second developing roller 53Y, the recovery roller 55Y, and the recovery screw 57Y each rotate using a motor as the driving source.

[0039] Case 200Y is a container extending in the Y direction and has a first circulation tank Sp1, a second circulation tank Sp2, and a recovery tank Sp3. The first circulation tank Sp1 and the second circulation tank Sp2 are spaces separated by a first partition wall 205 that extends in the Y direction. The first circulation tank Sp1 and the second circulation tank Sp2 are arranged side by side in the X direction with the first partition wall 205 in between. A first opening 209 and a second opening 207 are formed at both ends of the first partition wall 205 in the Y direction. The first opening 209 is an opening formed near the rear end of the first partition wall 205, and the second opening 207 is an opening formed near the front end of the first partition wall 205. The first circulation tank Sp1 and the second circulation tank Sp2 communicate with each other through the first opening 209 and the second opening 207, respectively. A replenishment port 217Y, which opens upward, is formed near the rear end in the Y direction of the second circulation tank Sp2. Developer is supplied to the second circulation tank Sp2 from the toner hopper 42Y through the replenishment port 217Y.

[0040] The recovery tank Sp3 is a space separated from the first circulation tank Sp1 by a second partition wall 206 that extends in the Y direction. The recovery tank Sp3 is located above the first circulation tank Sp1. The recovery tank Sp3 and the first circulation tank Sp1 are arranged side by side in the Z direction with the second partition wall 206 in between. A recovery port 213Y is formed near the rear end of the second partition wall 206 in the Y direction. The recovery port 213Y is an opening formed near the rear end of the second partition wall 206. The first circulation tank Sp1 and the recovery tank Sp3 are connected by the recovery port 213Y.

[0041] The first developing roller 51Y and the second developing roller 53Y are each cylindrical in shape and contain magnets with multiple magnetic poles. The first developing roller 51Y and the second developing roller 53Y are each driven to rotate while maintaining a small gap from the photoreceptor drum 23Y.

[0042] The first developing roller 51Y is positioned opposite the first screw 201Y, which is located in the first circulation tank Sp1. The first circulation tank Sp1 has a supply port 211Y between the first developing roller 51Y and the first screw 201Y. The supply port 211Y is an opening formed between the first circulation tank Sp1 and the first developing roller 51Y. The developer contained in the first circulation tank Sp1 is supplied to the first developing roller 51Y from the supply port 211Y. The first developing roller 51Y carries the developer supplied from the supply port 211Y. The first developing roller 51Y attracts magnetic carriers together with non-magnetic toner by magnetic force. As a result, the developer is carried by the first developing roller 51Y. The first developing roller 51Y and the second developing roller 53Y are attached to the case 200Y with a small gap between them. The second developing roller 53Y receives and carries the developer carried by the first developing roller 51Y.

[0043] The first developing roller 51Y and the second developing roller 53Y each have a portion of their circumference exposed from the case 200Y, and the portion exposed from the case 200Y faces the photoreceptor drum 23Y. The first developing roller 51Y and the second developing roller 53Y apply toner to the photoreceptor drum 23Y to develop the electrostatic latent image. Specifically, a development bias is applied to the first developing roller 51Y and the second developing roller 53Y. As a result, the potential of the circumferential surface of the first developing roller 51Y and the second developing roller 53Y is lower than the potential of the image-corresponding part of the photoreceptor drum 23Y (approximately 0V), and higher than the potential of the parts of the photoreceptor drum 23Y other than the image-corresponding part. The image-corresponding part is the portion of the circumferential surface of the photoreceptor drum 23Y that is irradiated with laser light by the exposure device 24Y. The toner in the developer carried by the first developing roller 51Y and the second developing roller 53Y is negatively charged, and therefore adheres to the image-corresponding portion on the circumferential surface of the photoreceptor drum 23Y. As a result, a toner image is formed on the circumferential surface of the photoreceptor drum 23Y by the negatively charged toner.

[0044] A recovery roller 55Y and a recovery screw 57Y are positioned in the recovery tank Sp3. The recovery roller 55Y is cylindrical in shape and elongated in the Y direction. The recovery roller 55Y is positioned opposite the second developing roller 53Y. The recovery roller 55Y peels off the developer, including toner and carrier, that was not carried on the photoreceptor drum 23Y from the second developing roller 53Y. The developer peeled off from the second developing roller 53Y slides down the bottom of the recovery tank Sp3. A portion of the toner contained in the developer carried on the first developing roller 51Y and a portion of the toner contained in the developer carried on the second developing roller 53Y are passed to the photoreceptor drum 23Y. Therefore, the toner concentration of the developer recovered from the second developing roller 53Y by the recovery roller 55Y is lower than the toner concentration supplied from the first circulation tank Sp1 to the first developing roller 51Y. Here, toner concentration is the proportion of toner in the developer.

[0045] The recovery screw 57Y is positioned below the recovery tank Sp3. The recovery screw 57Y has a cylindrical rotating shaft extending in the Y direction, with spiral blades on its outer circumference. The developer, recovered by the recovery roller 55Y and sliding down the bottom of the recovery tank Sp3, is transported backward in the Y direction within the recovery tank Sp3 by the rotation of the recovery screw 57Y. The developer transported backward in the Y direction within the recovery tank Sp3 falls into the first circulation tank Sp1 through the recovery port 213Y.

[0046] The first circulation tank Sp1 is a space that supplies developer to the first developing roller 51Y and collects any remaining developer after development is complete. An outlet 215Y for discharging the developer is located at the rear end of the first circulation tank Sp1 in the Y direction. The outlet 215Y communicates with a waste toner box (not shown). In this embodiment, the outlet 215Y is located downstream of the collection port 213Y in the transport direction.

[0047] The second circulation tank Sp2 is a space adjacent to the first circulation tank Sp1, separated by the first partition wall 205, and is a space for agitating and mixing the developer. The developer supplied from the toner hopper 42Y is replenished into the second circulation tank Sp2 through a replenishment port 217Y provided in the second circulation tank Sp2.

[0048] The first circulation tank Sp1 is equipped with a first screw 201Y, and the second circulation tank Sp2 is equipped with a second screw 203Y. Both the first screw 201Y and the second screw 203Y have a cylindrical rotating shaft extending in the Y direction, with spiral blades on the outer surface of the shaft. Both the first screw 201Y and the second screw 203Y transport the developer by rotating.

[0049] The first screw 201Y has three parts: a first section 221, a second section 223, and a third section 225. The first screw 201Y is provided with a first blade W1 on the first section 221 for transporting the developer towards the rear in the Y direction. The first section 221 is the portion of the first screw 201Y from the front end in the Y direction to the rear end of the first opening 209. The second section 223 is connected to the rear of the first section 221, and the third section 225 is connected to the rear of the second section 223. The second section 223 and the third section 225 are located behind the first opening 209. The second blade W2 is provided on the second section 223 of the first screw 201Y. The second blade W2 is wound in the opposite direction to the first blade W1. Therefore, the direction in which the first section 221 of the first screw 201Y transports the developer is opposite to the direction in which the second section 223 transports the developer. Therefore, the developer conveyed by the first part 221 of the first screw 201Y flows easily through the first opening 209 to the second circulation tank Sp2. In addition, a portion of the developer conveyed by the second part 223 of the first screw 201Y reaches the third part 225. The third part 225 has blades formed in the same direction as the first blade W1. The third part 225 conveys the developer backward in the Y direction and discharges it from the outlet 215Y connected to the waste toner box.

[0050] The second screw 203Y is located in the second circulation tank Sp2. The second screw 203Y has blades along its entire length. The second screw 203Y has a third blade W3 and a fourth blade W4. The third blade W3 is located in the direction-changing section corresponding to the second opening 207 of the second screw 203Y. The third blade W3 has a spiral shape that is opposite to that of the first blade W1. As the second screw 203Y rotates, the third blade W3 transports the developer forward in the Y direction. The fourth blade W4 is located in the direction-changing section and has a surface parallel to the Y direction. As the second screw 203Y rotates, the fourth blade W4 transports the developer to the left in the X direction. The developer transported by the fourth blade W4 proceeds towards the first circulation tank Sp1 side via the second opening 207. The second screw 203Y is responsible for agitating and conveying the developer in the second circulation tank Sp2 and the developer replenished from the replenishment port 217Y provided in the second circulation tank Sp2.

[0051] In the developing apparatus 21Y, the developer conveyed backward in the Y direction by the first screw 201Y in the first circulation tank Sp1 enters the second circulation tank Sp2 through the first opening 209. The developer that enters the second circulation tank Sp2 is conveyed forward in the Y direction by the second screw 203Y and returns to the first circulation tank Sp1 through the second opening 207. In this way, the developer circulates through the section from the second opening 207 to the first opening 209 in the first circulation tank Sp1 and the section from the first opening 209 to the second opening 207 in the second circulation tank Sp2.

[0052] Furthermore, if the pressure of the developer being transported by the first blade W1 within the first circulation tank Sp1 exceeds a predetermined value, a portion of the developer being transported within the first circulation tank Sp1 will not enter the second circulation tank Sp2 through the first opening 209, but will instead head toward the second blade W2. The developer that enters the second blade W2 will pass over the second blade W2 of the first screw 201Y and head toward the rear end of the first circulation tank Sp1 in the Y direction. The developer that has reached the rear end of the first circulation tank Sp1 in the Y direction will then be discharged from the opening into the waste toner box.

[0053] A detection unit 300Y is positioned between the supply port 211Y and the recovery port 213Y of the first circulation tank Sp1. The detection unit 300Y is positioned downstream of the supply port 211Y of the first circulation tank Sp1 in the direction of transport of the developer transported by the first screw 201Y. The detection unit 300Y is positioned at a distance of 1 unit downstream of the supply port 211Y of the first circulation tank Sp1. The detection unit 300Y is positioned upstream of the recovery port 213Y of the first circulation tank Sp1 in the direction of transport of the developer transported by the first screw 201Y. The detection unit 300Y is positioned at a distance of 2 units upstream of the recovery port 213Y of the first circulation tank Sp1.

[0054] Figure 5 is an enlarged XY cross-sectional view of the vicinity of the collection port of the developing unit. Figure 6 is a cross-sectional view along the CC line of Figure 5. Figure 7 is a diagram showing the cross-sectional view of Figure 3 with the detection unit added. Referring to Figures 5 to 7, the detection unit 300Y includes a paddle 301 and a photosensor 311. The photosensor 311 is fixed to the inner surface of the upper wall of the first circulation tank Sp1. The photosensor 311 has a light-emitting part and a light-receiving part. The photosensor 311 receives light emitted from the light-emitting part with the light-receiving part. The photosensor 311 detects the presence or absence of the paddle 301 in the detection area between the light-emitting part and the light-receiving part. The paddle 301 is rotatably mounted on the first screw 201Y. As shown in Figure 6, the outer diameter of the paddle 301 is determined to be the length over which the outer peripheral portion of the paddle 301 passes through the detection area of ​​the photosensor 311.

[0055] Figure 8 is a perspective view of the paddle. Figure 9 is a front view of the paddle. Referring to Figures 8 and 9, the paddle 301 has a bearing 303 and a plurality of fins 305. The plurality of fins 305 are arranged at multiple positions that divide the circumferential direction of the bearing 303 at equal intervals. The fins 305 extend radially outward from the bearing 303.

[0056] The bearing 303 is attached to the first screw 201Y such that its axis of rotation coincides with the axis of rotation of the first screw 201Y. Therefore, the paddle 301 is rotatable around the axis of rotation of the first screw 201Y. The paddle 301 rotates independently of the rotation of the first screw 201Y.

[0057] Multiple wing portions 305 have the same shape. Each wing portion 305 has a first inclined surface 307A and a second inclined surface 307B at the end opposite to the end connected to the bearing 303.

[0058] Figure 10 illustrates the first and second inclined surfaces of the wing portion. Referring to Figure 10, the first inclined surface 307A and the second inclined surface 307B of the wing portion 305 face opposite each other. The first inclined surface 307A faces forward in the Y direction, and the second inclined surface 307B faces backward in the Y direction. The first inclined surface 307A and the second inclined surface 307B each intersect the developer transport direction. The first inclined surface 307A and the second inclined surface 307B each are inclined at an angle less than 90 degrees with respect to the Y direction. The angles of inclination of the first inclined surface 307A and the second inclined surface 307B of each of the multiple wing portions 305 are the same.

[0059] As shown in Figure 5, the developer contained in the first circulation tank Sp1 is transported backward in the Y direction by the first screw 201Y. The multiple blades 305 receive force in the direction in which the developer flows from the developer transported by the first screw 201Y. As a result, the paddle 301 rotates around the rotation axis of the bearing 303. When the paddle 301 rotates, the multiple blades 305 pass through the detection area of ​​the photosensor 311 in sequence. The photosensor 311 detects when the blades 305 cross the detection area. The rotation speed of the paddle 301 is detected from the number of times the blades 305 cross the detection area of ​​the photosensor 311 per unit time.

[0060] Figure 11 is a block diagram showing an example of the main circuit of an image forming apparatus. Referring to Figure 11, the main circuit 110 is provided in one of the following: the paper feeder 2, the image forming apparatus 3, the image inspection apparatus 4, or the post-processing apparatus 5. Here, we will explain using the case where the main circuit 110 is provided in the image forming apparatus 3 as an example. Note that the main circuit 110 may be provided in a separate housing from the paper feeder 2, the image forming apparatus 3, the image inspection apparatus 4, and the post-processing apparatus 5.

[0061] The main circuit 110 includes a CPU (Central Processing Unit) 111 that controls the entire image forming system 1, a communication interface (I / F) unit 112, a ROM (Read Only Memory) 113, a RAM (Random Access Memory) 114, a hard disk drive (HDD) 115 as a large-capacity storage device, and an external storage device 117. The CPU 111 is connected to the paper feed device 2, the image forming apparatus 3, the image inspection apparatus 4, the post-processing device 5, and the operation panel 18, and controls the entire image forming system 1.

[0062] ROM113 stores the program that the CPU111 executes, or the data necessary to execute that program. RAM114 is used as a workspace when the CPU111 executes the program.

[0063] The control panel 18 is located on the upper part of the housing of the image forming apparatus 3. The control panel 18 includes a display unit 19a and an operation unit 19b. The display unit 19a is, for example, a liquid crystal display (LCD) and displays instruction menus for the user, information about acquired image data, etc. Instead of an LCD, any device that displays images may be used, such as an organic electroluminescent (EL) display.

[0064] The operating unit 19b includes a touch panel or hard keys. The touch panel detects a position indicated by the user on the display surface of the display unit 19a. The hard keys are, for example, contact switches.

[0065] The communication interface 112 is an interface for connecting the CPU 111 to a network. The communication interface 112 communicates with computers connected to the network using communication protocols such as TCP (Transmission Control Protocol) or FTP (File Transfer Protocol). The network to which the communication interface 112 is connected may be a local area network, a wide area network (WAN), a public switched telephone network (PSTN), the Internet, or other networks. Furthermore, the network connection method may be wired or wireless.

[0066] The external storage device 117 is fitted with a CD-ROM (Compact Disc Read Only Memory) 118. The CPU 111 can access the CD-ROM 118 via the external storage device 117. The CPU 111 loads the program recorded on the CD-ROM 118 fitted into the external storage device 117 into the RAM 114 and executes it.

[0067] Furthermore, the programs executed by the CPU 111 are not limited to those recorded on the CD-ROM 118. Instead of the CD-ROM 118, other media such as flexible disks, cassette tapes, optical disks, IC cards, optical cards, and semiconductor memory may be used. Optical disks include MO (Magnetic Optical Disc), MD (Mini Disc), and DVD (Digital Versatile Disc). Semiconductor memory includes flash memory and EPROM (Erasable Programmable Read Only Memory). Additionally, other computers connected to the network may rewrite programs stored on the HDD 115. Other computers connected to the network may also add and write new programs to the HDD 115. Furthermore, the CPU 111 may download programs from other computers connected to the network and store those programs on the HDD 115. The term "program" here includes not only programs that the CPU 111 can directly execute, but also source programs, compressed programs, encrypted programs, and so on.

[0068] Figure 12 is a block diagram showing an example of the functions of a CPU in an image forming apparatus. The functions shown in Figure 12 are realized by the CPU 111 of the image forming apparatus 3 when the CPU 111 executes a developing device adjustment program stored in the ROM 113 or HDD 115.

[0069] Referring to Figure 12, the CPU 111 of the image forming apparatus 3 includes a sensor control unit 61, a density acquisition unit 63, a size acquisition unit 65, a transport efficiency improvement unit 67, and a refresh unit 69. The sensor control unit 61 controls the photosensor 311. The sensor control unit 61 detects the rotational speed of the paddle 301 based on the output signal of the photosensor 311. The sensor control unit 61 outputs the rotational speed of the paddle 301 to the transport efficiency improvement unit 67. Here, the rotational speed includes the direction of rotation and the number of rotations per unit time. The rotational speed of the paddle 301 is positive in the transport direction of the developer transported by the first screw 201Y. The paddle 301 rotates by receiving force from the developer transported in the first circulation tank Sp1. Therefore, the rotational speed of the paddle 301 is information related to the speed at which the developer is transported.

[0070] The density acquisition unit 63 acquires the density of an image that the image forming apparatus 3 is intended to form. The density acquisition unit 63 processes image data included in a print job received from an external computer. The density acquisition unit 63 acquires the density of an edge region of the image data at a predetermined distance from the edge in the main scanning direction of the image data. The main scanning direction is parallel to the axis of the first developing roller 51Y. The density acquisition unit 63 acquires the density of the edge region on the rear side in the Y direction, among the two ends of the main scanning direction of the image data. The density acquisition unit 63 acquires the maximum value among the densities of multiple pixels included in the edge region. The density acquisition unit 63 may also acquire the average of the densities of multiple pixels included in the edge region. The density acquisition unit 63 outputs the acquired density to the transport efficiency improvement unit 67.

[0071] The size acquisition unit 65 acquires the size of the paper in the main scanning direction that the image forming apparatus 3 is to be used for image formation. The density acquisition unit 63 determines the size of the paper in the main scanning direction from the paper size and orientation specified in the print job received from an external computer. The size acquisition unit 65 outputs the size of the paper in the main scanning direction to the transport efficiency improvement unit 67.

[0072] The transport efficiency improvement unit 67 receives the rotation speed of the paddle 301 from the sensor control unit 61. When the rotation speed of the paddle 301 satisfies predetermined conditions, the transport efficiency improvement unit 67 improves the transport efficiency of the developer at least downstream of the supply port 211Y. The predetermined conditions are predefined conditions and are stored in the HDD 115. At the location where the detection unit 300Y is located, the developer may backflow. In particular, at the recovery port 213Y of the first circulation tank Sp1, the developer enters from the recovery tank Sp3, so the volume of developer increases, and the developer may backflow. The developer supplied from the recovery tank Sp3 through the recovery port 213Y has a low toner concentration. Therefore, when a developer with a low toner concentration is supplied to the first developing roller 51Y from the supply port 211Y, the toner concentration of the developer carried by the first developing roller 51Y becomes low. In this case, the quality of the toner image formed on the photoreceptor drum 23Y may deteriorate. Therefore, the specified conditions are those under which the developer flows backward, and a threshold value determined in advance through experimentation is set.

[0073] The transport efficiency improvement unit 67 includes a rotation control unit 71. The rotation control unit 71 increases the rotation speed of the first screw 201Y when the rotation speed of the paddle 301 falls below a threshold determined under predetermined conditions. This improves the transport efficiency of the developer contained in the first circulation tank Sp1 and eliminates backflow. As the transport efficiency of the developer contained in the first circulation tank Sp1 is improved, the transport efficiency of the developer downstream of the supply port 211Y in the circulation path is also improved.

[0074] The transport efficiency improvement unit 67 receives density input from the density acquisition unit 63. Even when the rotation speed of the paddle 301 meets predetermined conditions, the transport efficiency improvement unit 67 does not improve the transport efficiency of the developer if the density input from the density acquisition unit 63 is below the first threshold. If the density input from the density acquisition unit 63 is below the first threshold, it can be sufficiently covered by the toner in the developer carried on the first developing roller 51Y. Therefore, even if the toner density of the developer supplied to a part near the end of the first developing roller 51Y is low, it does not affect the formation of the toner image. In addition, increasing the rotation speed of the first screw 201Y accelerates the deterioration of the developer. Therefore, the lifespan of the developer can be extended as much as possible.

[0075] The transport efficiency improvement unit 67 receives the size of the recording medium from the size acquisition unit 65. Even if the rotation speed of the paddle 301 meets predetermined conditions, the transport efficiency improvement unit 67 does not improve the transport efficiency of the developer if the size of the recording medium input from the size acquisition unit 65 is less than or equal to the second threshold. If the size of the recording medium input from the size acquisition unit 65 is less than or equal to the second threshold, the portion of the developer carried on the first developing roller 51Y that carries a developer with a low toner concentration is not used for developing. Therefore, if the size of the recording medium input from the size acquisition unit 65 is less than or equal to the second threshold, even if the toner concentration of the developer supplied to the first developing roller 51Y is low, it does not affect the formation of the toner image. In addition, the lifespan of the developer can be extended as much as possible.

[0076] The transport efficiency improvement unit 67 outputs a refresh instruction to the refresh unit 69 if the rotation speed of the paddle 301 meets predetermined conditions after improving the transport efficiency of the developer. If the rotation speed of the paddle 301 meets predetermined conditions after improving the transport efficiency of the developer, there is a high probability that the developer has deteriorated.

[0077] The refresh unit 69 replaces the toner stored in the developing unit 21Y with new toner in response to a refresh instruction. Specifically, the refresh unit 69 consumes toner by creating a toner image on the photoreceptor drum 23Y that will not be transferred to the recording medium, while simultaneously replenishing new developer from the toner hopper 42Y through the replenishment port 217Y. Since the developer replenished from the toner hopper 42Y contains a carrier, the carrier is also replaced.

[0078] Figure 13 is a flowchart showing an example of the development device adjustment process. The development device adjustment process is performed by the CPU 111 of the image forming apparatus 3, which executes an adjustment program stored in the ROM 113 or HDD 115.

[0079] Referring to Figure 13, the CPU 111 of the image forming apparatus 3 sets the count flag to OFF and proceeds to step S02. The count flag is a flag that determines whether or not the transport efficiency improvement process, which will be described later, is executed. It is set to ON when the transport efficiency improvement process is executed, and to OFF before the transport efficiency improvement process is executed. In step S02, the paddle rotation speed is acquired, and the process proceeds to step S03. The rotation speed of the paddle 301 is acquired based on the output value of the photosensor 311.

[0080] In step S03, density is obtained, and the process proceeds to step S04. Based on the image data included in the print job, the density of a predetermined area is calculated from one end of the main scanning direction of the image data. The one end corresponds to the end of the first developing roller 51Y that is on the side of the collection port 213Y. The density of the area is the maximum value among multiple densities corresponding to each of the multiple pixels included in the area.

[0081] In step S04, the size of the recording medium to be image-formed is obtained, and the process proceeds to step S05. The size of the recording medium is determined by the print conditions included in the print job. The size of the recording medium is the size in the main scanning direction. The main scanning direction is the direction perpendicular to the direction in which the recording medium is transported.

[0082] In step S05, it is determined whether the rotational speed of the paddle 301 obtained in step S02 satisfies a predetermined condition. If the rotational speed of the paddle 301 satisfies the predetermined condition, the process proceeds to step S06; otherwise, the process returns to step S02. The predetermined condition is that the rotational speed is greater than or equal to a predetermined threshold. The predetermined threshold is a value determined in advance through experiments, etc., and is stored in the HDD 115 beforehand. The threshold is the rotational speed of the paddle 301 when the direction in which the developer flows is opposite to the direction in which it is transported by the first screw 201Y. Even when the direction in which the developer flows is opposite to the direction in which it is transported by the first screw 201Y, the rotational direction of the paddle 301 may not reverse. Therefore, it is preferable to determine the threshold experimentally.

[0083] In step S06, the process branches depending on the setting of the rotation flag. If the rotation flag is set to OFF, the process proceeds to step S07, but if the rotation flag is set to ON, the process proceeds to step S11.

[0084] In step S07, it is determined whether the concentration obtained in step S03 is less than or equal to the first threshold. If the concentration is less than or equal to the first threshold, the process proceeds to step S08; otherwise, the process proceeds to step S09. In step S08, it is determined whether the size of the recording medium obtained in step S04 is less than or equal to the second threshold. If the size of the recording medium is less than or equal to the second threshold, the process returns to step S02; otherwise, the process returns to step S09.

[0085] In step S09, the transport efficiency improvement process is executed, and the process proceeds to step S10. In this embodiment, the CPU 111 increases the rotation speed of the first screw 201Y. This increases the transport efficiency of the developer in the first circulation tank Sp1. The phenomenon of backflow of the developer near the paddle 301 is eliminated. In step S10, the count flag is set to ON, and the process returns to step S02.

[0086] The process proceeds to step S11 if the rotation speed of the paddle 301 meets the predetermined conditions and the count flag is set to ON. When the developer deteriorates, its fluidity decreases. If the rotation speed of the paddle 301 meets the predetermined conditions despite the transport efficiency improvement process being performed, it is often because the developer has deteriorated.

[0087] In step S11, a toner refresh process is performed, and the process returns to step S01. Specifically, the CPU 111 consumes toner by creating a toner image on the photoreceptor drum 23Y that will not be transferred to the recording medium, while replenishing new developer from the toner hopper 42Y through the replenishment port 217Y. By performing the toner refresh process, the CPU 111 replaces the toner stored in the developing unit 21Y with new toner.

[0088] Figure 14 shows an example of experimental data. Referring to Figure 14, the horizontal axis shows the rotational speed of the first screw 201Y, and the vertical axis shows the rotational speed of the paddle 301. The rotational speed is the number of rotations per unit time. Here, the normal range for the rotational speed of the paddle 301 is 65 (rpm) to 84 (rpm). The threshold is 65 rpm, which is the lower limit of the normal range. The normal range is the rotational speed of the paddle 301 when the flow direction of the developer is the same as the transport direction of the first screw 201Y. When the rotational speed of the paddle 301 is 65 (rpm) or less, there is a high probability that the flow direction of the developer will be opposite to the transport direction of the first screw 201Y.

[0089] Immediately after the toner refresh process was performed, the rotation speed of the first screw 201Y was 400 rpm, while the rotation speed of the paddle 301 was 82 rpm. Considering the lifespan of the developer, the rotation speed of the first screw 201Y should be as low as possible. Therefore, when the developer is not deteriorated, a rotation speed of 400 rpm for the first screw 201Y is sufficient.

[0090] The points indicated by the black circles show the rotation speed of paddle 301 relative to the rotation speed of the first screw 201Y, for developers with a low degree of deterioration. For example, when the rotation speed of the first screw 201Y is 400 rpm, the rotation speed of paddle 301 is 50 rpm. For example, when the rotation speed of the first screw 201Y is 450 rpm, the rotation speed of paddle 301 is 60 rpm. For example, when the rotation speed of the first screw 201Y is 500 rpm, the rotation speed of paddle 301 is 70 rpm. For example, when the rotation speed of the first screw 201Y is 550 rpm, the rotation speed of paddle 301 is 80 rpm.

[0091] For developers with a low degree of degradation, the rotation speed of the paddle 301 falls outside the normal range when the rotation speed of the first screw 201Y is 400 rpm and 450 rpm. When the rotation speed of the first screw 201Y is 500 rpm and 550 rpm, the rotation speed of the paddle 301 falls within the normal range. Therefore, it can be seen that if the rotation speed of the first screw 201Y is set to 500 rpm or higher, the direction in which the developer flows becomes the same as the transport direction of the first screw 201Y, and the transport efficiency is improved.

[0092] The points indicated by the black triangles show the rotation speed of the first screw 201Y and the rotation speed of the paddle 301 for developers with a high degree of deterioration. For example, when the rotation speed of the first screw 201Y is 400 rpm, the rotation speed of the paddle 301 is 40 rpm. For example, when the rotation speed of the first screw 201Y is 450 rpm, the rotation speed of the paddle 301 is 48 rpm. For example, when the rotation speed of the first screw 201Y is 500 rpm, the rotation speed of the paddle 301 is 56 rpm. For example, when the rotation speed of the first screw 201Y is 550 rpm, the rotation speed of the paddle 301 is 64 rpm.

[0093] For developers that have deteriorated significantly, the rotation speed of the paddle 301 falls outside the normal range when the rotation speed of the first screw 201Y is 400 rpm, 450 rpm, 500 rpm, and 550 rpm. Therefore, if the rotation speed of the paddle 301 does not fall within the normal range even when the rotation speed of the first screw 201Y is 550 rpm or higher, it can be determined that the developer has deteriorated. In this case, it is preferable to replace the deteriorated developer contained in the developing device 21Y with new developer by performing a toner refresh process.

[0094] <First variation> The detection unit 300Y of the developing device 21Y in the above-described embodiment has a paddle 301 that rotates around an axis parallel to the rotation axis of the first screw 201Y. In the first modified example, the detection unit 300Y of the developing device 21Y has a rotor 320 instead of a paddle 301.

[0095] Figure 15 is an XZ cross-sectional view of the developing apparatus in the first modified example. Figure 16 is an enlarged XY cross-sectional view of the vicinity of the collection port of the developing unit in the first modified example. Figure 17 is a perspective view of a part of the detection unit. Figure 18 is a plan view showing an enlarged view of another part of the detection unit. Referring to Figures 15 to 18, the detection unit 300Y in the first modified example includes a rotor blade 321, a blade rotation shaft 323, a detection unit 325, a first photosensor 331A, and a second photosensor 331B.

[0096] The blade rotation axis 323 is mounted on the case 200Y so as to be rotatable about an axis intersecting the rotation axis of the first screw 201Y. Four rotor blades 321 are mounted near the lower end of the blade rotation axis 323. The rotor blades 321 are plate-shaped members extending radially from the outer circumference of the blade rotation axis 323. The rotor blades 321 have a surface parallel to the blade rotation axis 323.

[0097] Four detection units 325 are attached near the upper end of the blade rotation axis 323. Each detection unit 325 is a plate-shaped member extending radially from the outer circumference of the blade rotation axis 323. Each detection unit 325 has a surface perpendicular to the blade rotation axis 323. The four detection units 325 are arranged at equal intervals in the circumferential direction of the blade rotation axis 323.

[0098] The first photosensor 331A and the second photosensor 331B are fixed to the outer surface of the upper wall of the first circulation tank Sp1. The first photosensor 331A and the second photosensor 331B are arranged at a predetermined distance apart in the circumferential direction of the blade rotation axis 323. Each of the first photosensor 331A and the second photosensor 331B receives light emitted from the light-emitting part with its light-receiving part. Each of the first photosensor 331A and the second photosensor 331B detects the presence or absence of the detected part 325 in the detection area between the light-emitting part and the light-receiving part.

[0099] The rotor blade 321 is positioned to contact the developer contained in the first circulation tank Sp1. When the developer contained in the first circulation tank Sp1 is transported by the first screw 201Y, the rotor blade 321 receives force from the developer and rotates. As the rotor blade 321 rotates, the detected parts 325 pass sequentially through the detection areas of the first photosensor 331A and the second photosensor 331B. Based on the outputs of the first photosensor 331A and the second photosensor 331B, the rotational speed of the blade rotation axis 323 is detected. In addition, the rotational direction of the blade rotation axis 323 is detected based on the order in which the four detected parts 325 pass through the detection areas of the first photosensor 331A and the second photosensor 331B. For example, by making the widths of the four detected parts 325 different, any of the four detected parts 325 can be detected by the first photosensor 331A and the second photosensor 331B, respectively.

[0100] Figure 19 shows an example of experimental data in the first modified example. Referring to Figure 19, the horizontal axis shows the rotational speed of the first screw 201Y, and the vertical axis shows the rotational speed of the blade rotation axis 323. The rotational speed is the number of rotations per unit time. Here, the normal range for the rotational speed of the blade rotation axis 323 is 30 (rpm) to 50 (rpm). The threshold is 30 rpm, which is the lower limit of the normal range. The normal range is the rotational speed of the blade rotation axis 323 when the flow direction of the developer is the same as the transport direction of the first screw 201Y. When the rotational speed of the blade rotation axis 323 is 30 (rpm) or less, there is a high probability that the flow direction of the developer will be opposite to the transport direction of the first screw 201Y.

[0101] Immediately after the toner refresh process was performed, the rotation speed of the blade rotation shaft 323 was 43 rpm compared to the rotation speed of the first screw 201Y at 400 rpm. Considering the lifespan of the developer, the rotation speed of the first screw 201Y should be as low as possible. Therefore, when the developer is not deteriorated, a rotation speed of 400 rpm for the first screw 201Y is sufficient.

[0102] The points indicated by the black circles show the rotation speed of the blade rotation shaft 323 relative to the rotation speed of the first screw 201Y, for a developer with a low degree of degradation. When the rotation speed of the first screw 201Y is 400 rpm, the rotation speed of the blade rotation shaft 323 is 15 rpm. When the rotation speed of the first screw 201Y is 450 rpm, the rotation speed of the blade rotation shaft 323 is 25 rpm. When the rotation speed of the first screw 201Y is 500 rpm, the rotation speed of the blade rotation shaft 323 is 35 rpm. When the rotation speed of the first screw 201Y is 550 rpm, the rotation speed of the blade rotation shaft 323 is 45 rpm.

[0103] For developers with a low degree of degradation, the rotation speed of the blade rotation shaft 323 falls outside the normal range when the rotation speed of the first screw 201Y is 400 rpm and 450 rpm. When the rotation speed of the first screw 201Y is 500 rpm and 550 rpm, the rotation speed of the blade rotation shaft 323 falls within the normal range. Therefore, it can be seen that if the rotation speed of the first screw 201Y is set to 500 rpm or higher, the direction in which the developer flows becomes the same as the transport direction of the first screw 201Y, and the transport efficiency is improved.

[0104] The points indicated by the black triangles show the rotation speed of the first screw 201Y and the rotation speed of the blade rotation shaft 323 for a developer with a high degree of deterioration. When the rotation speed of the first screw 201Y is 400 rpm, the rotation speed of the blade rotation shaft 323 is -4 rpm. When the rotation speed of the first screw 201Y is 450 rpm, the rotation speed of the blade rotation shaft 323 is 4 rpm. When the rotation speed of the first screw 201Y is 500 rpm, the rotation speed of the blade rotation shaft 323 is 11 rpm. When the rotation speed of the first screw 201Y is 550 rpm, the rotation speed of the blade rotation shaft 323 is 20 rpm.

[0105] For developers that have deteriorated significantly, the rotation speed of the blade rotation shaft 323 falls outside the normal range when the rotation speed of the first screw 201Y is 400 rpm, 450 rpm, 500 rpm, and 550 rpm. Therefore, if the rotation speed of the blade rotation shaft 323 does not fall within the normal range even when the rotation speed of the first screw 201Y is 550 rpm or higher, it can be determined that the developer has deteriorated. In this case, it is preferable to replace the deteriorated developer contained in the developing device 21Y with new developer by performing a toner refresh process.

[0106] In the first modified example, the detection unit 300Y has a first photosensor 331A and a second photosensor 331B, but the detection unit 300Y may have either the first photosensor 331A or the second photosensor 331B.

[0107] <Second variation> In the first modified example, the developing device 21Y has a detection unit 300Y positioned on the side of the first developing roller 51Y relative to the rotation axis of the first screw 201Y. In the second modified example, the developing device 21Y has a detection unit 300Y with the same configuration as in the first modified example, but is positioned on the side of the rotation axis of the first screw 201Y that is opposite to the first developing roller 51Y.

[0108] Figure 20 is an XZ cross-sectional view of the developing apparatus in the second modified example. Figure 21 is an enlarged XY cross-sectional view of the vicinity of the collection port of the developing unit in the second modified example. Referring to Figures 20 and 21, the detection unit 300Y in the second modified example is positioned on the opposite side of the first developing roller 51Y from the rotation axis of the first screw 201Y. The first screw 201Y is positioned between the detection unit 300Y and the first developing roller 51Y. The rotor blades 321 of the detection unit 300Y are not present between the first screw 201Y and the first developing roller 51Y.

[0109] In the second modified development apparatus 21Y, similar to the first modified development apparatus 21Y, the direction in which the developer contained in the first circulation tank Sp1 flows can be detected.

[0110] <Third variation> The detection unit 300Y of the developing apparatus 21Y in the above-described embodiment has a paddle 301 that rotates around an axis parallel to the rotation axis of the first screw 201Y. In the third modified example, the detection unit 300Y of the developing apparatus 21Y has a swinging mechanism instead of a paddle 301.

[0111] Figure 22 is an XZ cross-sectional view of the developing apparatus in the third modified example. Figure 23 is a YZ cross-sectional view of the vicinity of the detection unit of the developing unit in the third modified example. Referring to Figures 22 and 23, the detection unit 300Y in the third modified example includes a bearing 351, a contact unit 353, a detection unit 355, and a third photosensor 361. The detection unit 300Y in the third modified example is positioned between the rotation axis of the first screw 201Y of the first circulation tank Sp1 and the first developing roller 51Y. The third photosensor 361 is fixed to the inner surface of the upper wall of the first circulation tank Sp1 of the case 200Y. The third photosensor 361 has a light-emitting unit and a light-receiving unit.

[0112] The bearing 351 is fixed to the upper wall of the first circulation tank Sp1 of the case 200Y with its axis of rotation parallel to the X direction. A contact portion 353 and a detection portion 355 are connected to the outer circumference of the bearing 351. The contact portion 353 and the detection portion 355 are rod-shaped members that extend radially outward from the outer surface of the bearing 351. The contact portion 353 and the detection portion 355 form a predetermined angle in the circumferential direction of the bearing 351. The predetermined angle is 180 degrees or less. The contact portion 353 is heavier than the detection portion 355. For this reason, the contact portion 353 is located below the detection portion 355.

[0113] The third photosensor 361 receives light emitted from the light-emitting unit with its light-receiving unit. The third photosensor 361 detects the presence or absence of the detected unit 355 in the detection area between the light-emitting unit and the light-receiving unit. The length of the detected unit 355 is adjusted to correspond to the distance between the rotation center of the bearing 351 and the detection area of ​​the third photosensor 361.

[0114] The contact portion 353 has a length that allows it to contact the upper surface of the developer contained in the first circulation tank Sp1. Therefore, the contact portion 353 moves due to the force exerted by the developer contained in the first circulation tank Sp1. As the contact portion 353 moves, the bearing 351 rotates, and the detected portion 355 moves in the opposite direction to the movement of the contact portion 353. While the developer contained in the first circulation tank Sp1 flows in the same direction as the transport direction of the first screw 201Y, the third photosensor 361 detects the detected portion 355. While the developer contained in the first circulation tank Sp1 flows in the opposite direction to the transport direction of the first screw 201Y, the third photosensor 361 does not detect the detected portion 355.

[0115] In the third modified example, the transport efficiency improvement unit 67 of the CPU 111 improves the transport efficiency of the developer at least downstream of the supply port 211Y when the third photosensor 361 no longer detects the detection unit 355.

[0116] Furthermore, the third photosensor 361 may be configured to detect the detection unit 355 while the developer contained in the first circulation tank Sp1 is flowing in the opposite direction to the transport direction of the first screw 201Y. The third photosensor 361 does not detect the detection unit 355 while the developer contained in the first circulation tank Sp1 is flowing in the same direction as the transport direction of the first screw 201Y. In this case, the transport efficiency improvement unit 67 of the CPU 111 in the third modified example improves the transport efficiency of the developer at least downstream of the supply port 211Y in response to the third photosensor 361 detecting the detection unit 355.

[0117] In the first circulation tank Sp1, the developer entering from the recovery port 213Y accumulates on top of the developer in the first circulation tank Sp1. As a result, the toner concentration near the top surface of the developer becomes lower. Also, when the developer flows from a higher area to a lower area, the developer near the top surface moves downward. Therefore, detecting backflow near the top surface of the developer is effective.

[0118] <Fourth variation> In the third modified example, the developing apparatus 21Y has a detection unit 300Y positioned on the side of the first developing roller 51Y relative to the rotation axis of the first screw 201Y. In the fourth modified example, the developing apparatus 21Y has a detection unit 300Y with the same configuration as in the third modified example, but positioned on the side of the rotation axis of the first screw 201Y that is opposite to the first developing roller 51Y.

[0119] Figure 24 is a cross-sectional view of the developing apparatus in the fourth modified example, shown in Figure 24. Referring to Figure 24, in the fourth modified example, the detection unit 300Y is positioned on the opposite side of the rotation axis of the first screw 201Y from the first developing roller 51Y. The first screw 201Y is positioned between the detection unit 300Y and the first developing roller 51Y. There is no contact portion 353 of the detection unit 300Y between the first screw 201Y and the first developing roller 51Y.

[0120] In the fourth modified example, the developing apparatus 21Y can also detect the direction in which the developer contained in the first circulation tank Sp1 flows, similar to the developing apparatus 21Y in the third modified example.

[0121] <Fifth variation> Figure 25 is a YZ cross-sectional view of the developing apparatus in the fifth modified example. The difference from the detection unit 300Y of the developing apparatus 21Y in the third modified example shown in Figure 23 is that a floating member 357 is connected to the tip of the contact portion 353. The other configurations are the same as the detection unit 300Y of the developing apparatus 21Y in the third modified example.

[0122] The density of the floating member 357 is less than the density of the developer. The floating member 357 moves near the surface of the developer contained in the first circulation tank Sp1. In the fifth modified example, the developing apparatus 21Y makes it easy to detect the flow direction near the surface of the developer contained in the first circulation tank Sp1.

[0123] In addition, the detection unit 300Y in the developing device 21Y in the fifth modified example may be positioned on the opposite side of the rotation axis of the first screw 201Y from the first developing roller 51Y.

[0124] <Sixth variation> Figure 26 is a YZ cross-sectional view of the developing apparatus in the sixth modified example. The difference from the detection unit 300Y of the developing apparatus 21Y in the fifth modified example shown in Figure 25 is that the contact part 353 has been changed to a contact part 353A. The other configurations are the same as the detection unit 300Y of the developing apparatus 21Y in the fifth modified example.

[0125] The contact portion 353A is composed of a flexible material, at least in part. Here, an example is shown in which the entire contact portion 353A is made of a flexible material. As a result, the floating member 357 receives less force from the contact portion 353A, and therefore moves more easily in conjunction with the movement of the developer near the surface contained in the first circulation tank Sp1. This makes it easier to detect the flow direction near the surface of the developer contained in the first circulation tank Sp1.

[0126] <Seventh variation> The detection unit 300Y of the developing apparatus 21Y in the above-described embodiment has a paddle 301 that rotates around an axis parallel to the rotation axis of the first screw 201Y. In the seventh modified example, the detection unit 300Y of the developing apparatus 21Y has a pressure sensor instead of the paddle 301.

[0127] Figure 27 is an XZ cross-sectional view of the developing apparatus in the seventh modified example. Figure 28 is a YZ cross-sectional view of the vicinity of the detection unit of the developing unit in the seventh modified example. Referring to Figures 27 and 28, the detection unit 300Y in the seventh modified example includes a first pressure sensor 371 and a second pressure sensor 373. The first pressure sensor 371 and the second pressure sensor 373 are positioned between the rotation axis of the first screw 201Y of the first circulation tank Sp1 and the first developing roller 51Y. The first pressure sensor 371 and the second pressure sensor 373 are fixed to the inner surface of the upper wall of the first circulation tank Sp1 of the case 200Y. The first pressure sensor 371 and the second pressure sensor 373 are positioned near the upper surface of the developer being transported in the first circulation tank Sp1.

[0128] The first pressure sensor 371 and the second pressure sensor 373 have detection surfaces facing opposite directions. The detection surfaces intersect the transport direction of the developer conveyed by the first screw 201Y. Here, the first pressure sensor 371 has a detection surface facing away from the transport direction. The second pressure sensor 373 has a detection surface facing the transport direction. The first pressure sensor 371 and the second pressure sensor 373 are fixed to the inner surface of the case 200Y with their respective detection surfaces and the surfaces opposite to them facing each other.

[0129] In the seventh modified example, the transport efficiency improvement unit 67 of the CPU 111 calculates the transport speed of the developer being transported in the first circulation tank Sp1 from the difference between the pressure detected by the first pressure sensor 371 and the pressure detected by the second pressure sensor 373. If the calculated transport speed falls below a threshold, the transport efficiency improvement unit 67 improves the transport efficiency of the developer at least downstream of the supply port 211Y.

[0130] The first pressure sensor 371 and the second pressure sensor 373 may be positioned on the opposite side of the first developing roller 51Y from the rotation axis of the first circulation tank Sp1.

[0131] <Variation 8> In the above embodiment, the transport efficiency improvement unit 67 includes a rotation control unit 71, but the developing apparatus 21Y in this embodiment is not limited to this. In the circulation path formed by the first circulation tank Sp1 and the second circulation tank Sp2, a branching path tank connected to the portion downstream of the supply port 211Y of the first circulation tank Sp1 may be provided. The transport efficiency improvement unit 67 controls the developer being transported in the circulation path to enter the branching path tank when information related to the speed of the developer being transported in the circulation path satisfies predetermined conditions. This makes it possible to improve the transport efficiency of the developer in the region downstream of the supply port 211Y in the circulation path.

[0132] <Summary of Embodiments> (Item 1) A developing apparatus for developing an electrostatic latent image on an image carrier with a developer supported on a developing roller, A first circulation tank having a supply port for supplying a portion of the developer to the developing roller while conveying the developer in the transport direction, A second circulation tank that transports the developer, which is transported from the first circulation tank through a first opening, back to the first circulation tank through a second opening, A developing apparatus comprising: a detection unit that detects information related to the speed of the developer being transported in a circulation path formed by the first circulation tank and the second circulation tank.

[0133] In this configuration, the development apparatus includes a first circulation tank having a supply port for transporting developer while supplying a portion of the developer to the developing roller, and a second circulation tank that transports the developer from the first circulation tank through a first opening to the first circulation tank through a second opening. Information related to the speed of the developer in the circulation path formed by the first and second circulation tanks is detected. If the speed of the developer transported in the circulation path fluctuates, the appropriate amount of developer may not be supplied to the developing roller. Since information related to the speed of the developer is detected, the developer can be flowed at an appropriate speed. As a result, a developing apparatus can be provided that suppresses the deterioration of the quality of the toner image developed on the image carrier.

[0134] (Item 2) The detection unit has a rotating shaft and A wing portion having a surface that extends outward from the rotation axis and intersects the conveying direction, The developing apparatus according to claim 1, further comprising a speed detection unit for detecting the rotational speed of the blade portion around the rotation axis.

[0135] In this configuration, the blades extend outward from the rotation axis and have an inclined surface that is tilted relative to the direction of developer transport. As a result, the blades receive a force in the transport direction from the developer flowing through the circulation path and rotate around the rotation axis. Since the rotation speed of the rotation axis is detected, the speed in the direction of developer flow and the transport direction can be detected.

[0136] (Item 3) The developing apparatus according to Item 2, wherein the rotating shaft is parallel to the transport direction.

[0137] In this configuration, since the axis of rotation is parallel to the transport direction, the blades can be positioned in the area where the developer flows, allowing for efficient use of space.

[0138] (Item 4) The developing apparatus according to Item 2, wherein the rotating shaft intersects the transport direction.

[0139] Following this configuration, the axis of rotation intersects the conveying direction, increasing the degree of freedom in positioning the blades.

[0140] (Item 5) The detection unit has one end and the other end in one direction, and a driven member is attached to the first circulation tank, with an axis positioned between the one end and the other end and intersecting the transport direction, The developing apparatus according to claim 1, further comprising a position detection unit for detecting the position of the other end when one end is in contact with the developer being transported in the first circulation tank.

[0141] In this configuration, one end of the driven member comes into contact with the developer, and so that end moves with the flow of the developer. Since the position of the other end of the driven member is detected, the flow direction of the developer can be detected with a simple configuration.

[0142] (Item 6) At least a portion of the driven member between the shaft and one end is formed of a flexible member, The developing apparatus according to claim 5, wherein the detection unit further comprises a floating member attached to one end and having a specific gravity lighter than the developer.

[0143] In this configuration, at least a portion of the driven member between its shaft and one end is made of a flexible material, and a floating member is attached to the other end. Since the section between the middle and one end of the driven member is made of a flexible material, and the floating member has a lower specific gravity than the developer, the floating member moves along the surface of the flowing developer in accordance with the developer's flow. This allows for the detection of the flow direction on the surface of the developer.

[0144] (Item 7) The detection unit includes a first pressure sensor having a first detection surface facing the transport direction, The developing apparatus according to claim 1, comprising a second pressure sensor having a second detection surface facing opposite to the transport direction.

[0145] In this configuration, the first pressure sensor has a first detection surface facing the transport direction, and the second pressure sensor has a second detection surface facing the opposite direction of transport. Therefore, the pressure received from the developer in the transport direction and the pressure received in the opposite direction of transport can be detected. As a result, the direction and velocity of the developer flow can be detected.

[0146] (Item 8) The collection unit further includes a collection unit that collects a portion of the developer supplied to the developing roller and replenishes the collected developer to the first circulation tank through a collection port provided in the first circulation tank, The developing apparatus according to item 1, wherein the detection unit is located upstream of the recovery port in the first circulation tank.

[0147] In this scenario, a portion of the developer supplied to the developing roller is recovered, and the recovered developer is replenished into the first circulation tank from the recovery port. The volume of developer increases at and near the recovery port of the first circulation tank. Since the detection unit is located upstream of the recovery port in the first circulation tank, information regarding the developer velocity upstream of the region where the developer volume increases is detected. Therefore, it is possible to detect the velocity in regions where the developer velocity is prone to change. In addition, since the developer replenished from the recovery port has a lower toner concentration, it is possible to detect the backflow of developer with a relatively low toner concentration.

[0148] (Item 9) The developing apparatus according to Item 1, wherein the detection unit is located downstream of the supply port in the first circulation tank.

[0149] In this configuration, the detection unit is positioned downstream of the supply port in the first circulation tank. Since the developer is supplied from the supply port to the developing roller, it is preferable that the developer speed is constant in the supply port portion of the first circulation path. Because information regarding the developer speed downstream of the supply port is detected, the developer speed at the supply port can be predicted.

[0150] (Item 10) The developing apparatus according to any one of items 1 to 9, further comprising a transport efficiency improvement unit that improves the transport efficiency of the developer at least downstream of the supply port in response to the information regarding the speed of the developer detected by the detection unit satisfying predetermined conditions.

[0151] In this scenario, the transport efficiency of the developer downstream from the supply port is improved in response to the detection of a predetermined flow state of the developer. When the predetermined flow state is a decrease in speed in the transport direction or a reversal of the transport direction, the developer can be transported appropriately.

[0152] (Item 11) The system further comprises a screw having a shaft extending in the transport direction rotatably supported in the first circulation tank and having blades extending outward in a spiral manner from the shaft, The developing apparatus according to claim 7, wherein the transport efficiency improvement unit includes a rotation control unit that changes the rotation speed of the screw.

[0153] In this scenario, as the screw rotates, the helical blades transport the developer in the transport direction. Since the transport efficiency changes as the screw's rotation speed changes, the transport efficiency can be easily varied.

[0154] (Item 12) The developing apparatus according to item 11, wherein the detection unit is located upstream of the first opening in the first circulation tank.

[0155] In this configuration, the detection unit is positioned upstream of the first opening in the first circulation tank. The developer being transported in the first circulation tank is then transported to the second circulation tank through the first opening. Since the flow state of the developer upstream of the first opening is detected, it is possible to detect the flow state of the developer in areas where the developer is more likely to accumulate compared to other areas.

[0156] (Item 13) The developing apparatus according to item 10, further comprising a refresh unit that replaces the developer stored in the first circulation tank and the second circulation tank with new developer when the information regarding the speed of the developer detected by the detection unit after the transport efficiency improvement unit has improved the transport efficiency of the developer satisfies predetermined conditions.

[0157] In this scenario, if the developer transport efficiency is improved and the information regarding the developer's speed meets predetermined conditions, the developer stored in the first and second circulation tanks is replaced with new developer. If the developer transport efficiency is improved and the information regarding the developer's speed meets predetermined conditions, there is a high probability that the developer stored in the first and second circulation tanks is degraded. Therefore, the degraded developer can be replaced with new developer.

[0158] (Item 14) Further comprising a density acquisition unit that acquires the density of the edges of an image formed based on image data to be formed, The developing apparatus according to paragraph 10, wherein the transport efficiency improvement unit determines whether or not to improve the transport efficiency of the developer based on the acquired concentration when the information regarding the speed of the developer detected by the detection unit satisfies the predetermined conditions.

[0159] In this scenario, if the information regarding the developer's speed meets predetermined conditions, the decision to improve the developer's transport efficiency is made based on the density at the edges of the image formed based on the image data. When a predetermined flow state of the developer is detected, the image quality at the edges of the formed image deteriorates. The decision to improve the developer's transport efficiency is made based on the density at the edges of the formed image. Therefore, if the image quality of the formed image does not deteriorate, there is no need to improve the developer's transport efficiency, and thus the lifespan of the developer can be extended.

[0160] (Item 15) A size acquisition unit that acquires the size of the recording medium on which the image is to be formed, The developing apparatus according to paragraph 10, wherein the transport efficiency improvement unit determines whether or not to improve the transport efficiency of the developer based on the acquired size when the information regarding the speed of the developer detected by the detection unit satisfies the predetermined conditions.

[0161] In this scenario, if the information regarding the developer's speed meets certain conditions, the decision of whether or not to improve the developer's transport efficiency is made based on the size of the recording medium. When a predetermined flow state of the developer is detected, the image quality deteriorates at the end of the developing roller. If the size of the recording medium is small, the developer at the end of the developing roller is not used for image formation. Therefore, if the size of the recording medium is small, there is no need to improve the developer's transport efficiency, and the lifespan of the developer can be extended.

[0162] (Item 16) A developing apparatus as described in any of Items 1 to 15, An image forming apparatus comprising: a transfer unit for transferring a toner image developed on an image carrier with the developer to a recording medium.

[0163] Following this approach, it is possible to provide a developing device that suppresses the degradation of image quality.

[0164] (Item 17) A method for adjusting a developing apparatus that develops an electrostatic latent image on an image carrier with a developer supported on a developing roller, The developing apparatus includes a first circulation tank having a supply port for supplying a portion of the developer to the developing roller while conveying the developer in the transport direction, A second circulation tank that transports the developer, which is transported from the first circulation tank through a first opening, back to the first circulation tank through a second opening, The system includes a detection unit that detects information related to the speed of the developer being transported in the circulation path formed by the first circulation tank and the second circulation tank, A developing apparatus adjustment method, comprising a transport efficiency improvement step, which improves the transport efficiency of the developer downstream of the detection unit in accordance with the information regarding the speed of the developer detected by the detection unit satisfying predetermined conditions.

[0165] Following this approach, it is possible to provide a developing apparatus adjustment method that suppresses the deterioration of the quality of the toner image developed on the image carrier.

[0166] (Item 18) A developing apparatus adjustment program executed by a computer that controls a developing apparatus for developing an electrostatic latent image on an image carrier with a developer supported on a developing roller, The developing apparatus includes a first circulation tank having a supply port for supplying a portion of the developer to the developing roller while conveying the developer in the transport direction, A second circulation tank that transports the developer, which is transported from the first circulation tank through a first opening, back to the first circulation tank through a second opening, The system includes a detection unit that detects information related to the speed of the developer being transported in the circulation path formed by the first circulation tank and the second circulation tank, A developing device adjustment program that causes the computer to execute a transport efficiency improvement step to improve the transport efficiency of the developer downstream of the detection unit, in response to the information regarding the speed of the developer detected by the detection unit satisfying predetermined conditions.

[0167] Following this approach, it is possible to provide a developing device adjustment program that suppresses the deterioration of the quality of the toner image developed on the image carrier.

[0168] (Item 19) A partition wall is provided between the first circulation tank and the second circulation tank, The developing apparatus according to any one of claims 1 to 15, wherein the first opening and the second opening are formed in the partition wall.

[0169] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is indicated by the claims rather than by the foregoing description, and all modifications within the meaning and scope equivalent to the claims are intended to be included. [Explanation of symbols]

[0170] 1 Image forming system, 2 Paper feeder, 3 Image forming apparatus, 4 Image inspection apparatus, 5 Post-processing apparatus, 6 Processing apparatus, 7 Conveyor apparatus, 8 Cutting apparatus, 9 Paper output tray, 20Y, M, C, K Image forming unit, 21Y Developing apparatus, 22Y Charging roller, 23Y Photoreceptor drum, 24Y Exposure apparatus, 25Y Primary transfer roller, 41Y Toner bottle, 42Y Toner hopper, 51Y First developing roller, 53Y Second developing roller, 55Y Recovery roller, 57Y Recovery screw, 111 CPU, 200Y Case, 201Y First screw, 203Y Second screw, 205 First partition, 206 Second partition, 207 Second opening, 209 First opening, 211Y Supply port, 213Y Recovery port, 215Y Discharge port, 217Y Refill port, 221 Part 1, 223 Part 2, 225 Part 3, 300Y Detection unit, 301 Paddle, 303 Bearing, 305 Blade section, 307A First inclined surface, 307B Second inclined surface, 311 Photosensor, 320 Rotating blade, 321 Rotating blade, 323 Blade rotation axis, 325 Detected unit, 331A First photosensor, 331B Second photosensor, 351 Bearing, 353, 353A Contact section, 355 Detected unit, 357 Floating member, 361 Third photosensor, 371 First pressure sensor, 373 Second pressure sensor, Sp1 First circulation tank, Sp2 Second circulation tank, Sp3 Recovery tank, W1 First blade, W2 Second blade, W3 Third blade, W4 Fourth blade, 61 Sensor control unit, 63 Concentration acquisition unit, 65 Size acquisition unit, 67 Conveying efficiency improvement unit, 69 Refresh unit, 71 Rotation control unit.

Claims

1. A developing apparatus that develops an electrostatic latent image on an image carrier with a developer supported on a developing roller, A first circulation tank having a supply port for supplying a portion of the developer to the developing roller while conveying the developer in the transport direction, A second circulation tank that transports the developer, which is transported from the first circulation tank through the first opening, back to the first circulation tank through the second opening, A developing apparatus comprising: a detection unit for detecting information related to the speed of the developer being transported in a circulation path formed by the first circulation tank and the second circulation tank.

2. The detection unit has a rotating shaft and A wing portion having a surface that extends outward from the rotation axis and intersects the conveying direction, The developing apparatus according to claim 1, further comprising a speed detection unit for detecting the rotational speed of the blade portion around the rotation axis.

3. The developing apparatus according to claim 2, wherein the rotating shaft is parallel to the transport direction.

4. The developing apparatus according to claim 2, wherein the rotating shaft intersects the transport direction.

5. The detection unit has one end and the other end in one direction, and a driven member is attached to the first circulation tank, with an axis positioned between the one end and the other end that intersects the transport direction. The developing apparatus according to claim 1, further comprising a position detection unit that detects the position of the other end when one end is in contact with the developer being transported in the first circulation tank.

6. At least a portion of the driven member between the shaft and one end is formed of a flexible member, The developing apparatus according to claim 5, wherein the detection unit further comprises a floating member attached to one end and having a specific gravity lighter than the developer.

7. The detection unit includes a first pressure sensor having a first detection surface facing the transport direction, The developing apparatus according to claim 1, further comprising a second pressure sensor having a second detection surface facing opposite to the transport direction.

8. The system further includes a recovery unit that recovers a portion of the developer supplied to the developing roller and replenishes the recovered developer to the first circulation tank through a recovery port provided in the first circulation tank. The developing apparatus according to claim 1, wherein the detection unit is located upstream of the recovery port in the first circulation tank.

9. The developing apparatus according to claim 1, wherein the detection unit is located downstream of the supply port in the first circulation tank.

10. The developing apparatus according to any one of claims 1 to 9, further comprising a transport efficiency improvement unit that improves the transport efficiency of the developer at least downstream of the supply port in response to the information regarding the speed of the developer detected by the detection unit satisfying predetermined conditions.

11. The device further comprises a screw having a shaft extending in the conveying direction that is rotatably supported in the first circulation tank, and blades extending outward in a spiral manner from the shaft, The developing apparatus according to claim 10, wherein the transport efficiency improvement unit includes a rotation control unit that changes the rotation speed of the screw.

12. The developing apparatus according to claim 11, wherein the detection unit is located upstream of the first opening in the first circulation tank.

13. The developing apparatus according to claim 10, further comprising a refresh unit that, after improving the transport efficiency of the developer by the transport efficiency improvement unit, replaces the developer stored in the first circulation tank and the second circulation tank with new developer when the information regarding the speed of the developer detected by the detection unit satisfies the predetermined conditions.

14. The system further includes a density acquisition unit that acquires the density of the edges of an image formed based on image data to be used for image formation. The developing apparatus according to claim 10, wherein the transport efficiency improvement unit determines whether or not to improve the transport efficiency of the developer based on the acquired concentration when the information regarding the speed of the developer detected by the detection unit satisfies the predetermined conditions.

15. A size acquisition unit that acquires the size of the recording medium on which the image is to be formed, The developing apparatus according to claim 10, wherein the transport efficiency improvement unit determines whether or not to improve the transport efficiency of the developer based on the acquired size when the information regarding the speed of the developer detected by the detection unit satisfies the predetermined conditions.

16. A developing apparatus according to any one of claims 1 to 15, An image forming apparatus comprising: a transfer unit for transferring a toner image developed on an image carrier with the developer to a recording medium.

17. A method for adjusting a developing apparatus that develops an electrostatic latent image on an image carrier using a developer supported on a developing roller, The developing apparatus includes a first circulation tank having a supply port for supplying a portion of the developer to the developing roller while conveying the developer in the transport direction, A second circulation tank that transports the developer, which is transported from the first circulation tank through the first opening, back to the first circulation tank through the second opening, The system includes a detection unit that detects information related to the speed of the developer being transported in the circulation path formed by the first circulation tank and the second circulation tank, A developing apparatus adjustment method, comprising a transport efficiency improvement step, which improves the transport efficiency of the developer downstream of the detection unit in accordance with the information regarding the speed of the developer detected by the detection unit satisfying predetermined conditions.

18. A developing device adjustment program executed by a computer that controls a developing device that develops an electrostatic latent image on an image carrier with a developer supported on a developing roller, The developing apparatus includes a first circulation tank having a supply port for supplying a portion of the developer to the developing roller while conveying the developer in the transport direction, A second circulation tank that transports the developer, which is transported from the first circulation tank through the first opening, back to the first circulation tank through the second opening, The system includes a detection unit that detects information related to the speed of the developer being transported in the circulation path formed by the first circulation tank and the second circulation tank, A developing apparatus adjustment program that causes the computer to execute a transport efficiency improvement step to improve the transport efficiency of the developer downstream of the detection unit, in response to the information regarding the speed of the developer detected by the detection unit satisfying predetermined conditions.

Images