Developing device and image forming apparatus

Abstract

To provide a developing device that can adjust the discharge performance of developer from a developer container to appropriately control the amount of developer in the developer container, and an image forming apparatus including the developing device.SOLUTION: A developing device comprises: a developer container 101 that stores developer; a developer carrier (developing roller 102) that is arranged inside the developer container 101 and carries the developer inside the developer container 101; a discharge port 104 that discharges the developer inside the developer container 101 to the outside; a conveying member (supply screw 105) that supplies the developer inside the developer container 101 to the developer carrier and conveys the developer to the discharge port 104; an adjustment unit that adjusts the interval between a part of an outer wall located on the upstream side of the discharge port 104 in the developer container 101 in a direction in which the developer is conveyed by the conveying member and the conveying member facing the part of the outer wall; and a control unit that controls the adjustment unit.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a developing device and an image forming apparatus equipped with the developing device. [Background technology]

[0002] BACKGROUND ART Conventionally, electrophotographic image forming devices have been known in which an electrostatic latent image is formed on a charged photosensitive member by irradiating the photosensitive member with light, the formed electrostatic latent image is developed with toner to form a toner image, the formed toner image is transferred to paper, and the transferred toner image is heated and fixed, thereby forming an image on paper.

[0003] Conventional image forming devices have a developer forced discharge mode that stops the machine during printing to discharge the developer in order to control the amount of developer used for development. However, in recent years, some models have emerged that cannot stop printing while printing on a 3,000-meter roll of paper, making the developer forced discharge mode impossible. As a result, the amount of developer in the developer container may exceed its functional limit during printing, leading to poor charging performance and potential damage to the developer container due to packing or other issues. This problem tends to be particularly pronounced when forming images using white toner, which has a higher adhesion and trickle rate than other colors, or when forming images on paper using a continuous feed printer, which tends to feed high-coverage sheets.

[0004] An example of a graph showing the relationship between the number of prints (time) and the amount of developer is shown in Figure 21. In the figure, symbol G1 is a graph when the coverage is 10%, and symbol G2 is a graph when the coverage is 100%. At normal coverage (10%), printing is completed before the upper limit of the function is reached. Therefore, by adjusting the developer amount before the next job, operation can be carried out without any problems. On the other hand, with high coverage (100% coverage) such as the combination of white toner and continuous feed press, the developer amount increases so quickly that the upper limit of the functionality is exceeded during printing. It is possible to avoid exceeding the upper limit of the functionality during printing by shifting the initial weight, etc., toward the lower limit, but since the lower limit is regulated for a different function, it is not possible to shift the initial weight, etc., toward the lower limit.

[0005] Therefore, a configuration has been disclosed in which an outlet is provided on the upper surface of the developer transport path, and developer overflowing from the outlet is discharged to prevent the amount of developer from increasing too much (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-47891 Summary of the Invention [Problem to be solved by the invention]

[0007] However, the configuration described in Patent Document 1 is a configuration in which developer overflowing from a discharge port is discharged. While it can prevent the amount of developer from increasing beyond a certain level, it cannot target and control the amount of developer to an appropriate level. In particular, it cannot address cases in which the amount of developer decreases too much. When the amount of developer decreases too much, problems such as screw irregularities occur, resulting in poor image quality. Furthermore, when the amount of developer increases suddenly, the developer cannot be discharged in time, resulting in poor screw rotation.

[0008] The present invention aims to provide a developing device that can adjust the developer discharge performance from a developing container to appropriately control the amount of developer in the developing container, and an image forming device equipped with such a developing device. [Means for solving the problem]

[0009] The invention described in claim 1 has been made to achieve the above object, In the developing device, a developer container that contains a developer; a developer carrier disposed in the developer container and carrying the developer in the developer container; a discharge port for discharging the developer in the developing container to the outside; a conveying member that supplies the developer in the developing container to the developer carrier and conveys the developer to the discharge port; In a developing device comprising: an adjustment unit that adjusts a gap between a part of an outer wall located upstream of the discharge port of the developing container in a direction in which the developer is transported by the transport member and the transport member that faces the part of the outer wall; a control unit that controls the adjustment unit; Equipped with 、 The control unit controls the adjustment unit based on print information for a sheet on which an image is formed. It is characterized by the following.

[0010] The invention described in claim 2 is the developing device described in claim 1, A reverse conveying member that conveys the developer in a direction opposite to the conveying direction is provided at a portion of the conveying member that faces the part of the outer wall.

[0012] Claim 3 The invention described in claim 1 In the developing device described in The control unit calculates the timing for adjustment by the adjustment unit based on the print information, and controls the adjustment unit at the calculated adjustment timing.

[0013] Claim 4 The invention described in claims 1 to 3 In the developing device according to any one of the preceding claims, a developer amount detection unit that detects the amount of developer in the developer container, The control unit controls the adjustment unit based on the amount of developer detected by the developer amount detection unit.

[0014] Claim 5 The invention described in In the image forming apparatus, an image forming unit that forms an image on a sheet; The image forming unit includes: an image carrier; 1 to 3, wherein a developer is supplied to the electrostatic latent image formed on the image carrier to form a toner image. 4 a developing device according to any one of the preceding claims; The present invention is characterized by comprising: [Effects of the Invention]

[0015] According to the present invention, the developer discharge performance from the developer container can be adjusted, and the amount of developer in the developer container can be appropriately controlled. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a diagram showing a schematic configuration of an image forming system according to an embodiment of the present invention; [Figure 2] FIG. 1 is a diagram illustrating a schematic configuration of an image forming apparatus. [Figure 3] FIG. 2 is a functional block diagram showing a control structure of the image forming system according to the present embodiment. [Figure 4] FIG. 2 is a plan view showing a schematic configuration of a developing unit. [Figure 5] FIG. 2 is a side view showing the configuration of the vicinity of the discharge port of the developing unit (supply screw). [Figure 6] FIG. 4 is a side view of the developing unit as viewed from the discharge port side in the axial direction of each screw. [Figure 7] FIG. 10 is a graph showing an example of the relationship between the developer container-supply screw gap and the amount of developer. [Figure 8] 10A and 10B are diagrams illustrating the relationship between the position of the cover and the flow of developer. [Figure 9] FIG. 2 is a side view showing a schematic configuration of an adjustment unit. [Figure 10] 10A and 10B are diagrams illustrating an example of how an adjustment member moves up and down in response to rotation of a cam. [Figure 11] FIG. 10 is a diagram showing an example of a graph of the amount of developer in the developer container until the end of printing when printing is performed with 100% coverage. [Figure 12] FIG. 4 is a side view of the developing unit as viewed from the opposite side of the discharge port in the axial direction of each screw. [Figure 13] 4 is a flowchart showing the operation of the image forming system according to the present embodiment (Example 1). [Figure 14] 10 is a diagram showing an example of a table in which print information (coverage and number of sheets passed) is associated with the pressing amount; FIG. [Figure 15] 10A and 10B are diagrams showing an example of the correspondence relationship between the pushing amount and coverage and the amount of developer after one roll has passed; [Figure 16] 10 is a flowchart showing the operation of the image forming system according to the present embodiment (Example 2). [Figure 17] 10 is a diagram showing an example of a table in which the difference between the current value and the target value of the amount of developer in the developer container is associated with the adjustment value of the cover position. FIG. [Figure 18] 10 is a flowchart showing the operation of the image forming system according to the first modification. [Figure 19] FIG. 10 is a diagram showing an example of the correspondence relationship between the amount of push-in and coverage and the amount of developer that varies over approximately 1000 prints. [Figure 20] FIG. 10 is a diagram showing an example of a graph of the amount of developer in the developer container until the end of printing when printing is performed with a coverage of 70%. [Figure 21] FIG. 10 is a diagram showing an example of a graph showing the relationship between the number of prints (time) and the amount of developer in the prior art. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0018] As shown in FIG. 1, an image forming system 100 according to this embodiment includes an image forming apparatus 1, a paper feeder 2, and a winder 3.

[0019] The paper feeder 2 stores continuous paper M, such as roll paper or continuous forms, and feeds the continuous paper M to the image forming apparatus 1. The image forming apparatus 1 forms an image on continuous paper M fed from a paper feeder 2. The winding device 3 winds the continuous paper M sent out by the image forming device 1 into a roll in accordance with instructions from the image forming device 1.

[0020] As shown in Figures 2 and 3, the image forming device 1 is configured to include a control unit 11, an image reading unit 12, an image forming unit 13, a memory unit 14, an operation panel 15 (display unit 151, operation unit 152), and a communication unit 16.

[0021] The control unit 11 is configured to include a CPU, RAM, ROM, etc. The CPU reads out various processing programs stored in the ROM in response to an operation signal input from the operation unit 152 or an instruction signal received by the communication unit 16, and loads the programs into the RAM, and performs overall control of the operation of the image forming apparatus 1 in cooperation with the various programs loaded into the RAM. The control unit 11 controls, for example, the adjustment unit 107 to adjust the gap between the cover 101a of the developing container 101 and the supply screw 105 facing the cover 101a.

[0022] The image reading unit 12 scans and exposes an image of a document placed on a document table or an automatic document feeder (ADF), not shown, using the optical system of a scanning exposure device, and reads the reflected light using a line image sensor, thereby obtaining an image signal. This image signal undergoes A / D conversion, shading correction, compression, and other processes, and is then input to the control unit 11 as image data. Note that the image data input to the control unit 11 is not limited to data read by the image reading unit 12, and may also be data received from an external device (not shown) via the communication unit 16, for example.

[0023] The image forming unit 13 forms an image made up of five colors, Y, M, C, K, and W (white), on a sheet of paper in accordance with the pixel values ​​of the five colors of each pixel of the image-processed original image. As shown in FIG. 2, the image forming unit 13 includes five writing units 131, an intermediate transfer belt 132, a secondary transfer roller 133, a fixing unit 134, and the like.

[0024] The five writing units 131 are arranged in series (tandem) along the belt surface of the intermediate transfer belt 132, and form images of the colors Y, M, C, K, and W. The writing units 131 have the same configuration except for the colors of the images they form, and are each equipped with an optical scanning unit 131a, a photosensitive member (image carrier) 131b, a developing unit 131c, a charging unit 131d, a cleaning unit 131e, and a primary transfer roller 131f.

[0025] During image formation, in each writing unit 131, the photoconductor 131b is charged by the charging unit 131d, and then a light beam emitted by the optical scanning unit 131a is scanned over the photoconductor 131b based on the original image to form an electrostatic latent image. When the developing unit 131c supplies developer and develops the image, an image (toner image) is formed on the photoconductor 131b. The images formed on the photoconductors 131b of the five writing units 131 are transferred (primary transfer) onto the intermediate transfer belt 132 in a sequentially overlapping manner by the respective primary transfer rollers 131f. As a result, images made of each color are formed on the intermediate transfer belt 132. The intermediate transfer belt 132 is wound around multiple rollers and rotates. After the primary transfer, the cleaning unit 131e removes coloring material remaining on the photoconductors 131b.

[0026] The secondary transfer roller 133 is one of a pair of rollers, one of which is in pressure contact with the intermediate transfer belt 132 and the other of which is wound around the intermediate transfer belt 132. When the image is transferred (secondary transfer) from the intermediate transfer belt 132 onto the paper by the pressure of the secondary transfer roller 133, the paper is transported to the fixing unit 134 where it is fixed, and then the paper is discharged to the winding device 3 by the paper discharge roller R1. The fixing process is a process in which the fixing roller 134a applies heat and pressure to the paper to fix the image onto the paper.

[0027] The developing unit 131c is, for example, a developing device that uses a two-component development method. Fig. 4 is a plan view showing a schematic configuration of the developing unit 131c, and Fig. 5 is a side view showing the configuration of the developing unit 131c in the vicinity of the discharge port 104. Fig. 5 is an enlarged side view of the area indicated by the symbol E1 in Fig. 4. As shown in FIGS. 4 and 5, the developing unit 131c includes a developing container 101 containing a two-component developer consisting of toner and carrier; a developing roller (developer carrier) 102 rotatably disposed at the opening of the developing container 101, which carries the developer in the developing container 101 and deposits it on the surface of the opposing photoconductor 131b; an agitating screw 103 that agitates the supplied developer while transporting it to a supply screw 105; an outlet 104 that discharges the developer in the developing container 101 to the outside; a supply screw (transport member) 105 that transports the developer in the developing container 101 to the outlet 104 while supplying it to the developing roller 102; and a liquid level detection sensor (developer amount detection unit) 106 that detects the amount of developer in the developing container 101. The developer discharged from the outlet 104 is collected in a collection box (not shown) via a waste toner pipe TP. The arrow F1 in the figure indicates the flow of the developer. A part of the developer transported by the supply screw 105 is transported to the stirring screw 103 and then transported by the stirring screw 103 again.

[0028] As shown in FIGS. 5 and 6, a vertically movable cover 101a is provided on a portion of the outer wall located upstream of the discharge port 104 of the developing container 101 in the direction of developer transport by the supply screw 105. An elastic member 101b is provided at the contact portion between the tip of the cover 101a on the discharge port 104 side and the developing container 101, capable of sealing a gap to prevent developer leakage. The elastic member 101b is made of, for example, Moltoprene (registered trademark), which has excellent sealing properties. The positions of the shaft of the supply screw 105 attached to the developing container 101 and the bottom of the developing container 101 are fixed. The normal position of the cover 101a is a position where the elastic member 101b is pressed in by a predetermined amount (see FIG. 8A). The cover 101a is capable of moving up and down relative to the normal position (see FIGS. 8B and 8C). In the above configuration, by moving the cover 101a up and down, it is possible to adjust the distance N1 between a part of the outer wall of the developing container 101 (cover 101a) and the supply screw 105 facing that part of the outer wall. This makes it possible to change the developer discharge performance, and to adjust the amount of developer in the developing container 101 during printing so that it is within an appropriate range.

[0029] 7 shows an example of a graph of the relationship between the amount of developer and the gap between the developing container 101 and the supply screw 105. The horizontal axis in FIG. 7 indicates the variation of the gap between the developing container 101 and the supply screw 105 from the reference position (center). It is known that the behavior of developer amount discharge changes depending on the distance between the developer container 101 and the supply screw 105. For example, it is known that when the distance between the developer container 101 and the supply screw 105 is below a certain level, the amount of developer increases significantly. In normal usage (sheet-fed paper use, low coverage), this can be addressed by specifying upper and lower limits of the tolerance of the distance between the developer container 101 and the supply screw 105 to prevent excessive developer discharge. For example, in this embodiment, the target tolerance of the distance between the developer container 101 and the supply screw 105 is set to within ±0.7 mm (upper tolerance limit ≒ +0.7 mm, lower tolerance limit ≒ -0.7 mm).

[0030] If the gap between the developing container 101 and the supply screw 105 is within the upper and lower tolerance limits (within ±0.7 mm) and is used normally (coverage 10%), the effect of an increase or decrease in the amount of developer can be ignored. However, if the distance between the developing container 101 and the supply screw 105 exceeds the upper tolerance limit (+0.7 mm) or is less than the lower tolerance limit (-0.7 mm), the amount of developer increases or decreases significantly, and the risk of malfunction increases as the distance between the developing container 101 and the supply screw 105 increases from the center (±0 mm). If the gap between the developing container 101 and the supply screw 105 becomes too narrow, it becomes difficult for the developer to be discharged, and the amount of developer in the developing container 101 increases, which causes the developer to overflow from the developing container 101 and increases the torque load on the motor that turns the supply screw 105, resulting in a malfunction. On the other hand, if the gap between the developing container 101 and the supply screw 105 becomes too wide, the developer is easily discharged, and the amount of developer in the developing container 101 decreases, causing screw irregularities and resulting in poor images.

[0031] 8 is a diagram illustrating the relationship between the position of the cover 101a and the flow of the developer, where arrow F1 indicates the flow of the developer. Under normal circumstances (low coverage, image formation using toner other than white), the amount of developer does not increase excessively, so the position of the cover 101a is kept at the reference position HP as shown in FIG. 8(A). When the rate of increase in the amount of developer increases sharply, such as when white toner is combined with high coverage, the cover 101a is moved upward to widen the gap between the developer container 101 and the supply screw 105, as shown in Figure 8(B), making it easier to discharge the developer. When the amount of developer is likely to decrease due to high toner concentration, high temperature and humidity, etc., the cover 101a is moved downward to narrow the gap between the developing container 101 and the supply screw 105, as shown in Figure 8(C), making it difficult for the developer to be discharged.

[0032] Next, the adjustment unit 107 that moves the cover 101a up and down will be described with reference to FIGS. As shown in FIG. 9, the adjustment unit 107 is configured to include a cam 107a, a motor 107b that rotates the cam 107a, and an adjustment member 107c that moves up and down in response to the rotation of the cam 107a. Adjustment member 107c is fixed to the upper surface of cover 101a and adjusts the position of cover 101a by moving up and down in response to the rotation of cam 107a, as shown in Fig. 10. When the downward pressing force caused by the rotation of cam 107a weakens, cover 101a and adjustment member 107c are pushed back upward by the elasticity of elastic member 101b (see Figs. 5 and 6). By having the above-mentioned configuration, the adjustment unit 107 adjusts the distance between a part of the outer wall (cover 101a) located upstream of the discharge outlet 104 of the developing container 101 in the direction in which the developer is transported by the supply screw 105 and the supply screw 105 that faces the part of the outer wall (cover 101a).

[0033] 11 shows an example of a graph of the amount of developer in the developer container 101 until the end of printing when printing is performed at 100% coverage on roll paper (enough for approximately 15,000 prints) used in a continuous feed printer. In the figure, symbol L1 indicates the example, and symbol L2 indicates the comparative example (conventional example). In the comparative example in which the gap between the developing container 101 and the supply screw 105 is constant, it is clear that the target upper limit line and the malfunction occurrence line are exceeded early. On the other hand, in the embodiment in which the distance between the developing container 101 and the supply screw 105 is widened, the target upper limit line is not exceeded even after printing is completed, and it can be seen that it can be used even under conditions in which the developer increases excessively (coverage 100%). That is, by adjusting the distance between the developing container 101 and the supply screw 105, the amount of developer can be kept within a usable range for any condition (coverage).

[0034] 5, a reverse-winding screw (reverse conveying member) 105a that conveys the developer in the opposite direction to the conveying direction is provided at a portion of the outer wall of the supply screw 105 facing the cover 101a. By providing the reverse-winding screw 105a to the supply screw 105, a force is applied that pushes back the developer being conveyed to the discharge port 104, so that only the developer that has gone over the reverse-winding screw 105a is discharged from the discharge port 104, making it possible to prevent excessive discharge of the developer.

[0035] 4 and 12, a liquid level detection sensor 106 is provided on the outside of the side surface (side wall) of the developing container 101 on the side where the stirring screw 103 is housed, for monitoring the current liquid level state of the developer in the developing container 101 and detecting the amount of developer in the developing container 101. Note that the symbol H1 in FIG. 12 indicates the liquid level of the developer.

[0036] The developing device of the present invention is configured to include at least a developing unit 131c (developing container 101, developing roller (developer carrier) 102, discharge port 104, supply screw (conveying member) 105), an adjusting unit 107, and a control unit 11.

[0037] Next, the operation of the image forming system 100 according to this embodiment (Example 1) will be described with reference to the flowchart in Fig. 13. Example 1 is an adjustment performed before printing starts, and the adjustment unit 107 is controlled based on print information for the paper on which an image is formed.

[0038] First, the control unit 11 acquires print information (number of sheets passed, amount of toner attached, image coverage, etc.) for the paper on which an image is to be formed (step S101).

[0039] Next, the control unit 11 estimates the amount of developer increase based on the print information acquired in step S101 (step S102).

[0040] Next, the control unit 11 determines whether or not it is necessary to change the position of the cover 101a (the amount of pressing of the cover 101a by the adjustment unit 107) based on the amount of increase in the developer estimated in step S102 (step S103). When the control unit 11 determines that the position of the cover 101a needs to be changed (step S103: YES), the process proceeds to the next step S104. On the other hand, if the control unit 11 determines that the position of the cover 101a does not need to be changed (step S103: NO), the control unit 11 ends the process.

[0041] Next, the control unit 11 determines the position of the cover 101a based on the amount of developer increase estimated in step S102 (step S104).

[0042] In this embodiment, when the cover 101a is not pressed in by the adjustment unit 107 (push-in amount = 0), the gap between the developing container 101 and the supply screw 105 is at its maximum, resulting in the largest amount of developer being discharged. The normal position of the cover 101a is when it is pressed in by 0.7 mm by the adjustment unit 107 (push-in amount = 0.7). Therefore, when the amount of developer in the developing container 101 is too small, the pushing amount is increased (up to 1.4 mm), and when the amount of developer in the developing container 101 is too large, the pushing amount is decreased.

[0043] In the first embodiment, the position (push amount) of the cover 101a is determined based on the developer increase amount estimated in step S102, but this is not limiting. For example, instead of estimating the developer increase amount, the average coverage may be calculated from the output image at the start of printing, and the push amount may be determined by referring to a table that associates the calculated average coverage with the number of prints and the push amount. Fig. 14 shows an example of a table T1 that associates print information (coverage and number of sheets passed) with the push amount.

[0044] FIG. 15 shows an example of the correspondence relationship between the pushing amount and coverage and the amount of developer after one roll (approximately 15,000 prints) has passed. In the example shown in Fig. 15, the developer amount decreases as the pushing amount decreases and the coverage decreases. In other words, as shown in Fig. 14, by setting the pushing amount according to the coverage (and the number of sheets passed), it is possible to avoid exceeding the upper limit or falling below the lower limit of the specifications.

[0045] Next, the control unit 11 changes the position of the cover 101a based on the position of the cover 101a determined in step S104 (step S105).

[0046] Next, the operation of the image forming system 100 according to this embodiment (Example 2) will be described with reference to the flowchart in Fig. 16. Example 2 is an adjustment performed during printing, and the adjustment unit 107 is controlled based on the amount of developer in the developing container 101.

[0047] First, the control unit 11 starts printing based on the print job (step S201).

[0048] Next, the control unit 11 acquires the amount of developer in the developing container 101 detected by the liquid level detection sensor 106 (step S202).

[0049] Next, the control unit 11 determines whether the amount of developer acquired in step S202 is within a predetermined range (step S203). Here, the predetermined range refers to a range in which the amount of developer is within a specification range and adjustment of the position (pressing amount) of the cover 101a by the adjustment unit 107 is not required. If the control unit 11 determines that the amount of developer acquired in step S202 is within a predetermined range (step S203: YES), it determines that adjustment of the position of the cover 101a is not necessary, and proceeds to step S205. On the other hand, if the control unit 11 determines that the amount of developer acquired in step S202 is not within the predetermined range (step S203: NO), it determines that adjustment of the position of the cover 101a is necessary, and proceeds to the next step S204.

[0050] Next, the control unit 11 adjusts the position of the cover 101a based on the amount of developer acquired in step S202 (step S204), and then the control unit 11 proceeds to step S205. Specifically, the control unit 11 calculates the difference Δ between the current amount of developer acquired in step S202 and the target value, and adjusts the position of the cover 101a by referring to table T2 (see FIG. 17) which associates the calculated difference Δ with an adjustment value for the position of the cover 101a (normal position = 0 mm). For example, if the current amount of developer acquired in step S202 is 10,000 and the target value is 8,600, then the difference Δ = 10,000 - 8,600 = 1,400, and the adjustment value for the position of the cover 101a is determined to be -0.2 mm (moving it upward by 0.2 mm to widen the gap) by referring to table T2. This makes it easier to discharge the developer, so the current amount of developer decreases and the current value can approach the target value. On the other hand, for example, if the current value of the developer amount acquired in step S202 is 6800 and the target value is 10000, the difference Δ=6800-10000=-3200, and the adjustment value for the position of the cover 101a is determined to be +0.3 mm (moving it downward by 0.3 mm to narrow the gap) by referring to table T2. This makes it more difficult for the developer to be discharged, so the current value of the developer amount increases and can be brought closer to the target value. Note that if the adjustment value for the position of the cover 101a exceeds the upper or lower limits of the specifications, it is fixed at the upper or lower limits of the specifications.

[0051] Next, the control unit 11 determines whether printing is in progress (step S205). If the control unit 11 determines that printing is in progress (step S205: YES), the process proceeds to step S202, and the processes from step S202 onwards are repeated. On the other hand, if it is determined that printing is not in progress (step S205: NO), the control unit 11 determines that the print job has ended, and ends the process.

[0052] In the above-described first embodiment, an example is described in which the position of the cover 101a is determined based on print information, and in the second embodiment, an example is described in which the position of the cover 101a is adjusted based on the amount of developer in the developer container 101. However, the first embodiment and the second embodiment may be combined. That is, after performing the processes of steps S101 to S105 in FIG. 13, the processes of steps S201 to S205 in FIG. 16 may be performed. In this way, the position of the cover 101a can be estimated before the start of printing, and then the position of the cover 101a can be adjusted while constantly monitoring the actual amount of developer during printing, thereby enabling efficient adjustment of the position of the cover 101a.

[0053] As described above, the developing device of the image forming apparatus 1 according to this embodiment includes a developing container 101 that contains a developer, a developer carrier (developing roller 102) that is arranged in the developing container 101 and carries the developer in the developing container 101, an outlet 104 that discharges the developer in the developing container 101 to the outside, a transport member (supply screw 105) that transports the developer in the developing container 101 to the outlet 104 while supplying it to the developer carrier, an adjustment unit 107 that adjusts the distance between a part of the outer wall (cover 101a) located upstream of the outlet 104 of the developing container 101 in the direction in which the developer is transported by the transport member and the transport member that faces the part of the outer wall, and a control unit 11 that controls the adjustment unit 107. Therefore, according to the developing device of this embodiment, the developer discharge performance from the developing container 101 can be adjusted, making it possible to appropriately control the amount of developer in the developing container 101 and suppressing the occurrence of functional failures.

[0054] Furthermore, in the developing device according to this embodiment, a reverse conveying member (reverse winding screw 105a) that conveys the developer in the direction opposite to the conveying direction is provided at a portion facing a part of the outer wall of the conveying member. Therefore, according to the developing device of this embodiment, a pushing force can be applied to the developer being transported to the discharge port 104, so that only the developer that has overcome the reverse-winding screw 105a can be discharged from the discharge port 104, thereby preventing excessive discharge of developer.

[0055] Furthermore, in the developing device according to this embodiment, the control unit 11 controls the adjustment unit 107 based on print information for the paper on which the image is formed. Therefore, according to the developing device of this embodiment, the position of the cover 101a can be adjusted predictably before the start of printing, so that the amount of developer in the developing container 101 can be controlled efficiently.

[0056] Furthermore, the developing device according to this embodiment is provided with a developer amount detection unit (liquid surface detection sensor 106) that detects the amount of developer in the developer container 101. Furthermore, the control unit 11 controls the adjustment unit 107 based on the amount of developer detected by the developer amount detection unit. Therefore, according to the developing device of this embodiment, the position of the cover 101a can be adjusted while monitoring the actual amount of developer at any time during printing, so that the amount of developer in the developing container 101 can be appropriately controlled.

[0057] The above has been a specific description based on an embodiment of the present invention, but the present invention is not limited to the above embodiment and can be modified within the scope of the gist thereof.

[0058] (Variation 1) For example, in the above embodiment, a configuration (Example 1) in which the position of the cover 101a is determined based on print information before printing starts is described as an example, but the present invention is not limited to this. For example, the timing for adjusting the position (pressing amount) of the cover 101a by the adjustment unit 107 may be calculated based on the print information, and the adjustment unit 107 may be controlled at the calculated adjustment timing. The operation of the image forming system 100 according to the first modification will be described below with reference to the flowchart of FIG.

[0059] First, the control unit 11 acquires print information (number of sheets passed, amount of toner attached, image coverage, etc.) for the paper on which an image is to be formed (step S301).

[0060] Next, the control unit 11 calculates the timing for adjusting the position of the cover 101a by the adjustment unit 107 based on the print information acquired in step S301 (step S302). For example, the control unit 11 calculates the adjustment timing by referring to information (see FIG. 19) indicating the correspondence between the print information and the amount of developer that varies over a predetermined number of prints (e.g., 1,000 prints). FIG. 19 shows an example of the correspondence between the print information (push-in amount and coverage) and the amount of developer that varies over approximately 1,000 prints. The control unit 11 calculates the adjustment timing by referring to the amount of developer fluctuation estimated from the print information. For example, if the amount of developer fluctuation estimated from the print information is large, the control unit 11 calculates the adjustment timing so that the number of adjustments is increased. On the other hand, if the amount of developer fluctuation estimated from the print information is small, the control unit 11 calculates the adjustment timing so that the number of adjustments is decreased.

[0061] Next, the control unit 11 starts printing based on the print job (step S303).

[0062] Next, the control unit 11 determines whether or not it is time for the adjustment unit 107 to make an adjustment (step S304). When the control unit 11 determines that it is time for the adjustment unit 107 to make an adjustment (step S304: YES), the control unit 11 makes the adjustment unit 107 make an adjustment (step S305), and the process proceeds to step S306. On the other hand, if the control unit 11 determines that it is not time for adjustment by the adjustment unit 107 (step S304: NO), the process proceeds to step S306.

[0063] Next, the control unit 11 determines whether printing is in progress (step S306). If the control unit 11 determines that printing is in progress (step S306: YES), the process proceeds to step S304, and the processes from step S304 onwards are repeated. On the other hand, if it is determined that printing is not in progress (step S306: NO), the control unit 11 determines that the print job has ended, and ends the process.

[0064] 20 shows an example of a graph of the amount of developer in the developing container 101 until the end of printing when printing is performed with a coverage of 70%. In the figure, symbol L3 indicates the example, and symbol L4 indicates the comparative example (conventional example). In the comparative example where the gap between the developing container 101 and the supply screw 105 is constant, it is clear that the target upper limit line is exceeded around 2000 prints, and the developer continues to accumulate thereafter. On the other hand, in an embodiment in which the timing for adjusting the position of the cover 101a is determined based on the printing information (every 1000 prints in the example shown in Figure 20), and the distance between the developing container 101 and the supply screw 105 is adjusted during printing, the target upper limit line is not exceeded even after printing is completed, and it can be seen that the device can be used effectively even under conditions in which the developer increases excessively (70% coverage). That is, even if the liquid level detection sensor 106 does not have the function of detecting the amount of developer, the position of the cover 101a can be adjusted during printing using only the print information.

[0065] As described above, the control unit 11 calculates the adjustment timing by the adjustment unit 107 based on the printing information, and controls the adjustment unit 107 at the calculated adjustment timing, thereby gradually adjusting the position of the cover 101a during printing. This makes it possible to appropriately control the amount of developer in the developing container 101 while gradually changing it, thereby reducing the load on various mechanisms in the developing unit 131c and suppressing the occurrence of functional failures.

[0066] (Other variations) In the above embodiment, the cover 101a is provided on the portion of the outer wall of the developing container 101 that faces the reverse-winding screw 105a, but this is not limiting. That is, the cover 101a only needs to be provided on at least the portion that faces the reverse-winding screw 105a, and may be configured to extend to a portion that does not face the reverse-winding screw 105a.

[0067] In the above embodiment, a configuration in which the adjustment unit 107 is controlled based on the amount of developer in the developing container 101 detected by the liquid level detection sensor 106 has been described as an example, but the present invention is not limited to this. For example, instead of the liquid level detection sensor 106, a sensor that detects the amount of developer discharged from the developing container 101 to the photosensitive member 131b or the like may be provided, and the adjustment unit 107 may be controlled based on the amount of developer detected by the sensor.

[0068] In addition, the detailed configuration and operation of each device constituting the image forming system can be modified as appropriate without departing from the spirit of the present invention. [Explanation of symbols]

[0069] 100 Image forming system 1. Image forming device 11 Control section 12 Image reading unit 13 Image forming unit 131 Writing section 131a Optical scanning unit 131b Photosensitive member (image carrier) 131c Development section 101 Developer container 101a Cover (part of the exterior wall) 101b Elastic member 102 Developing roller (developer carrier) 103 Agitating screw 104 Outlet 105 supply screw (conveying member) 105a Reverse winding screw (reverse conveying member) 106 Liquid level detection sensor (developer amount detection unit) 107 Adjustment section 131d Charging part 131e Cleaning Department 131f Primary transfer roller 132 Intermediate transfer belt 133 Secondary transfer roller 134 Fixing section 14 Storage section 15 Operation panel 151 Display section 152 Operation section 16 Communications Department 2 Paper feeder 3 Winding device

Claims

1. a developer container that contains a developer; a developer carrier disposed in the developer container and carrying the developer in the developer container; a discharge port for discharging the developer in the developing container to the outside; a conveying member that supplies the developer in the developing container to the developer carrier and conveys the developer to the discharge port; In a developing device comprising: an adjustment unit that adjusts a gap between a part of an outer wall located upstream of the discharge port of the developing container in a direction in which the developer is transported by the transport member and the transport member that faces the part of the outer wall; a control unit that controls the adjustment unit; Equipped with The developing device, wherein the control unit controls the adjustment unit based on print information for a sheet of paper on which an image is formed.

2. 2. The developing device according to claim 1, wherein a reverse transport member for transporting the developer in a direction opposite to the transport direction is provided at a portion of the transport member facing the portion of the outer wall.

3. 2. The developing device according to claim 1, wherein the control unit calculates an adjustment timing for the adjustment unit based on the print information, and controls the adjustment unit at the calculated adjustment timing.

4. a developer amount detection unit that detects the amount of developer in the developer container, 4. The developing device according to claim 1, wherein the control unit controls the adjustment unit based on the amount of developer detected by the developer amount detection unit.

5. an image forming unit that forms an image on a sheet; The image forming unit includes: an image carrier; a developing device according to any one of claims 1 to 4, which supplies a developer to the electrostatic latent image formed on the image carrier to form a toner image; An image forming apparatus comprising:

Images