JP5516427B2 - Developer deterioration state detection device, image forming apparatus, and developer deterioration state detection method - Google Patents

Description

  The present invention relates to a developer deterioration state detection device that detects a deterioration state of a developer used in an electrophotographic system, an image forming apparatus including the same, and a developer deterioration state detection method using these devices.

  In general, in an electrophotographic development process, when development is repeated for a long period of time, there is a problem in that the developer deteriorates, the charging ability of the developer decreases, and the image quality decreases. There are two-component developers and one-component developers, but when two-component developers are used, in the normal development system, the toner is consumed for each development and new toner is replenished. Although updated, the carrier continues to be used. When the development is repeated for a long period of time, the resin coat layer on the carrier surface is worn away in the developer, or the toner constituents adhere to and aggregate on the carrier surface, and the charging ability of the carrier decreases. For this reason, various adverse effects such as fluctuations in the image density and missing of the rear end of the solid image occur. In order to solve the problem of the deteriorated carrier, it is only necessary to replace all the developers. However, this work is very time-consuming and problematic.

  In addition, in the case of a one-component developer, it is sufficient that the developer supplied to the developing device is consumed in order from the oldest, but the developer stays in the developing device without being smoothly circulated, or the developer The developer may deteriorate due to the fact that the toner is not consumed for a long time. In addition, deterioration may be accelerated depending on environmental conditions.

  As a countermeasure against the above problem when using a two-component developer, there is a trickle development method. In the trickle developing method, the carrier is supplied together with the toner supply, while the excess developer is discharged and the carrier in the developing device is replaced little by little to stabilize the charge amount. The carrier can be replenished by mixing the carrier with the replenished toner, or the carrier and the toner can be replenished separately. According to the trickle developing method, the deteriorated developer can be automatically replaced, so that the problem of time and effort is solved.

  However, the trickle developing method also has a problem that the developer deteriorates and the fluidity deteriorates due to factors such as environmental conditions, the printing rate of an image to be formed, or the durability of the developer. Deterioration of the developer fluidity leads to fluctuations in the toner chargeability of the developer and density unevenness of the output image.

  As a developing device that solves such problems, by controlling the amount of developer replenished and discharged, including the carrier, and the amount of developer in the developing device, fluctuations in the toner chargeability of the developer and image density unevenness can be prevented. A technique for avoiding this is disclosed (for example, see Patent Document 1). In the image forming apparatus described in Patent Document 1, the flowability of the developer is controlled in order to maintain the toner chargeability of the developer, and a numerical value is defined and adjusted so that the repose angle of the developer falls within a predetermined range. doing. The angle of repose of the developer is small when the fluidity of the developer is high, and is large when the fluidity is low. The technology of Patent Document 1 uses this phenomenon to measure the developer fluidity and control the amount of fluctuation of the developer to prevent the occurrence of fog or density unevenness in the output image. is there.

JP 2005-283865 A

  However, in Patent Document 1, when measuring the angle of repose (deposition state) of the developer, it is necessary to take out the developer in the developing device once and put it into a measuring instrument, which takes a lot of time. There is a problem that labor is required. Further, the technique of Patent Document 1 is based on the trickle development method and cannot be applied to a one-component developer.

  The object of the present invention is to solve the above-mentioned problems, detect the developer deposition state without taking it out of the developing device, and detect the developer degradation state from which the developer fluidity and degradation state can be detected. It is an object to provide a means, an image forming apparatus, and a developer deterioration state detection method. In addition, by detecting the deterioration state of the developer accurately using the developer deterioration state detecting means, the image forming conditions of the image forming apparatus are controlled to suppress the deterioration of the developer, and a continuously stable image. There is in getting.

  The object is achieved by the following invention.

1. Developer carrying means for carrying out the developer stored in the developing device from the developing device;
A developer discharge port that is disposed on the developer carry-out path of the developer carry-out means and causes the developer carried out by the developer carry-out means to fall downward;
A developer depositing stage disposed below the developer discharge port and depositing the developer falling from the developer discharge port;
A deposition state detecting means for detecting a deposition state of the developer deposited on the developer deposition table;
A deterioration state detecting means for detecting the deterioration state of the developer from the developer deposition state;
A developer deterioration state detecting device characterized by comprising:

  2. 2. The developer deterioration state detecting apparatus according to claim 1, wherein the accumulation state detecting unit measures an angle of repose of the developer deposited on the developer accumulation stand.

  3. 2. The developer deterioration state detection apparatus according to 1, wherein the accumulation state detection unit measures a mass of the developer deposited on the developer accumulation stand.

  4). 2. The developer deterioration state detection apparatus according to 1, wherein the accumulation state detection unit measures a magnetic permeability of the developer deposited on the developer accumulation stand.

  5. 5. An image forming apparatus comprising the developer deterioration state detecting device according to any one of 1 to 4 above.

6). Image forming condition changing means for changing image forming conditions;
Control means for controlling the operation of the image forming condition changing means,
6. The image forming apparatus according to 5, wherein the control unit controls an operation of the image forming condition changing unit according to a detection result by the deterioration state detecting unit.

7). A developer supply device for supplying the developer;
Control means for controlling the operation of the developer supply device,
The image forming condition changing means is a developer replenishing device that replenishes the developing device with developer.
7. The image forming apparatus according to 6, wherein the control unit controls a supply amount of the developer supplied by the developer supply device according to a detection result by the deterioration state detection unit.

8). The image forming condition changing unit changes a developing bias condition applied to the developing device,
7. The image forming apparatus according to 6, wherein the control unit changes a developing bias condition applied to the developing device according to a detection result by the deterioration state detecting unit.

  9. 5. A developer deterioration state, wherein the developer deterioration state is detected from the developer accumulation state deposited on the developer deposition table using the developer deterioration state detection device according to any one of 1 to 4. Detection method.

  10. 9. A developer deterioration state detection method, wherein a deterioration state is detected from a deposition state of a developer deposited on the developer deposition stand using the image forming apparatus according to any one of 5 to 8.

  According to the present invention, the fluidity of the developer can be easily detected in a short time with a simple configuration, and the deterioration state can be grasped from the fluidity of the developer. Further, the developer deterioration can be suppressed by correcting the developer replenishment amount and the image forming condition based on the detection result.

1 is a configuration diagram of an embodiment of an image forming apparatus including a developer deterioration state detecting device according to the present invention. It is an expanded sectional view for demonstrating the structure and operation | movement of embodiment of the image development apparatus concerning this invention. FIG. 3 is a schematic cross-sectional view for explaining the configuration of the first embodiment of a developer deterioration state detection device 410 according to the present invention. It is a schematic block diagram for demonstrating the structure of 2nd Embodiment of the developing agent degradation state detection apparatus 410 which concerns on this invention. It is a schematic block diagram for demonstrating the structure of 3rd Embodiment of the developer deterioration state detection apparatus 410 which concerns on this invention. It is a schematic block diagram for demonstrating the structure of 4th Embodiment of the developer deterioration state detection apparatus 410 which concerns on this invention. FIG. 4 is a block diagram for explaining control of a control unit 100 that controls the operation of the image forming apparatus according to the present invention. 5 is a graph showing the relationship between the angle of repose θ and the number of printed sheets in Table 4.

  The present invention will be described below based on the embodiments, but the present invention is not limited to the embodiments.

  FIG. 1 is a configuration diagram of an embodiment of an image forming apparatus including a developer deterioration state detecting device according to the present invention. The image forming apparatus according to the present embodiment includes an image forming apparatus main body A and a document reading unit B.

  The illustrated image forming apparatus main body A includes a photosensitive drum 1, a charging unit 2, an image exposure unit (image writing unit) 3, a developing unit 4, a transfer unit 5, a charge eliminating unit 6, a separation claw 7, a cleaning unit 8, and the like. And an image forming unit, a fixing unit, and a paper conveyance system.

  The paper transport system includes a first transport unit including a paper feed cassette 10, a first paper feed unit 11, a second paper feed unit 12, a transport unit 13, a paper discharge unit 14, and a manual paper feed unit 15; It is composed of a circulation refeeding section that circulates and refeeds paper.

  The paper feed cassette 10 and the first paper feed means 11 are formed by a plurality of paper feed means (three stages in the figure), and accommodate and feed a plurality of types of paper P. The paper size is input by manual setting by the operation unit 21 or automatic paper size setting by the paper size detecting means.

  The image data of the document read by the document reading unit B described later is read by the image sensor CCD. The analog signal photoelectrically converted by the image sensor CCD is subjected to analog processing, A / D conversion, shading correction, image compression processing, and the like in an image processing unit, and then sent to the image exposure means 3.

  In the image exposure means 3, the output light from the semiconductor laser is irradiated onto the photosensitive drum 1 of the image forming unit to form a latent image. In the image forming unit, processes such as charging, exposure, development, transfer, separation, and cleaning are performed. An image is transferred by the transfer means 5 on the paper P fed from the paper feed cassette 10 and the manual paper feed means 15. The paper P carrying the image is fixed by the fixing unit 9 and discharged from the paper discharge unit 14.

  Alternatively, the single-sided image processed paper P sent to the circulation refeed unit by the conveyance path switching unit 16 is reversed by the reverse conveyance roller 17 and then subjected to double-sided image processing in the image forming unit, and then fixed by the fixing unit 9. The paper is processed and discharged by the paper discharge means 14.

  The developing device 4 in this embodiment is based on a trickle developing method using a two-component developer, and the developer deterioration state detecting device of the present invention is disposed in the vicinity of the developing device 4 and is discharged from the developing device 4. Upon receiving the developer, the deterioration state of the developer is detected.

  A detailed configuration in an embodiment of the image forming apparatus main body A provided with the developer deterioration state detecting device according to the present invention will be described in one embodiment of the image forming apparatus main body A and other embodiments described later.

  The control unit 100 is disposed inside the image forming apparatus main body A, and performs transmission and reception of signals between the image forming apparatus main body A and the document reading unit B, and controls operations of each part of the image forming apparatus main body A.

  In the description of the image forming apparatus main body A in the present embodiment, the formation of a monochrome image has been described. However, the present invention can also be applied to the case of forming a color image.

  FIG. 2 is an enlarged cross-sectional view for explaining the configuration and operation of the embodiment of the developing device according to the present invention. The developing device 4 in the present embodiment has a so-called trickle developing system configuration, and supplies toner T from the toner replenishing device 60 and carrier C from the carrier replenishing device 70, and the deteriorated developer is disposed below. The developer is discharged from the developer carrying housing 41B.

  The developing device 4 is disposed at a position that maintains a predetermined gap with respect to the circumferential surface of the photosensitive drum 1, and a developing roller 42 whose circumferential surface moves in a direction opposite to the moving direction of the circumferential surface of the photosensitive drum 1 in the development region. It has. Reference numeral 40 denotes a developing device housing as a developer containing portion for containing a two-component developer, and 42 denotes a developer transport having a magnet roll having a fixed magnetic pole inside and a sleeve rotating outside thereof. A developing roller as a body. Further, 43 is a layer thickness regulating member as a layer thickness regulating means made of a magnetic material that regulates the developer layer thickness on the developing roller 42 to a predetermined amount, 45 is a conveyance supply roller, and 46 and 47 are a pair of stirring screws. is there.

  The sleeve of the developing roller 42 is made of a non-magnetic cylindrical member having an outer shape of 8 mm to 60 mm using, for example, a stainless material, and is not shown provided on both ends of the developing roller 42 with respect to the peripheral surface of the photosensitive drum 1. A predetermined gap is provided by the abutting roller. Since the developing roller 42 is rotated in the same rotation direction as the photosensitive drum 1 (counterclockwise direction indicated by an arrow in FIG. 2), the opposing outer peripheral surfaces move in the opposite directions. A magnet roll (not shown) included in the developing roller 42 has a plurality of magnetic poles N and S alternately arranged, and is fixed at a concentric position with a sleeve (not shown) of the developing roller 42, and is arranged on the peripheral surface of the nonmagnetic sleeve. Magnetic force is applied.

  The layer thickness regulating member 43, which is a layer thickness regulating means, is made of, for example, a rod-like or plate-like magnetic stainless steel material, is opposed to a predetermined magnetic pole of the magnet roll, and is disposed at a predetermined gap from the sleeve of the developing roller 42. The layer thickness of the two-component developer on the surface is regulated. The conveyance supply roller 45 conveys the developer peeled off from the developing roller 42 to the stirring screw 46 and supplies the developer stirred by the stirring screw 46 to the layer thickness regulating member 43. The conveyance supply roller 45 is formed with a blade portion for conveying the developer.

  The developer supply device according to the present invention includes a toner supply device 60 and a carrier supply device 70, and supplies the developer (toner T and carrier C) to the developing device 4. The toner T is supplied from the toner replenishing device 60 when the toner concentration detection sensor (not shown) detects that the toner concentration in the developing device housing 40 is lower than a predetermined toner concentration. On the other hand, for the carrier C, a new carrier C is replenished in a timely manner from the carrier replenishing device 70 based on the accumulated amount of copies.

  The toner T and carrier C replenished by the toner replenishing device 60 and the carrier replenishing device 70 are developed from the toner replenishing port H (T) and the carrier replenishing port H (C) opened in the top plate 41A above the stirring screw 47. It is supplied into the housing 40. The toner T and the carrier C supplied into the developing device housing 40 are agitated and mixed with the developer contained in the developing device housing 40 by the agitating screws 46 and 47 that rotate at opposite speeds in opposite directions. The developer has a uniform toner density. The developer is conveyed to the layer thickness regulating member 43 by the rotating conveyance supply roller 45, and is made a predetermined layer thickness by the layer thickness regulating member 43, and a stable developer layer is formed on the outer peripheral surface of the developing roller 42. . The latent image on the photosensitive drum 1 is developed by the developer layer, and the developer that has been developed is peeled off by the action of the repulsive magnetic field of the magnetic pole of the magnet roll inside the developing roller 42 and stirred again by the conveyance supply roller 45. It is conveyed to the screw 46.

  The electrostatic latent image on the photosensitive drum 1 is in contact with the developer layer mounted on the developing roller 42 in the developing region, and a developing bias voltage is applied to superimpose an alternating current (AC) bias on a direct current (DC) bias. Then, reversal development is performed.

  The developing bias voltage in the present embodiment is applied to the sleeve of the developing roller 42 by the developing bias changing means BH including the variable frequency AC bias power supply AC1 and the DC bias power supply E1.

  In the present embodiment, the development bias condition is changed by changing the frequency of the AC bias power supply AC1, but the voltage of the AC bias power supply AC1 or the DC bias power supply E1 may be changed.

  The amount of toner T replenished from the toner replenishing device 60 is similar to the amount of toner T consumed by the development, but the carrier C replenished from the carrier replenishing device 70 is not consumed. The amount of developer in 40 is increased.

  An opening 40b for discharging the developer is formed below the stirring screw 47 on the upstream side in the normal developer conveying direction. When the amount of developer in the developing device housing 40 increases due to the supply of the carrier C from the carrier supply device 70 and the interface level rises, the developer may be in an increased state by an interface level detection unit (not shown) that detects the interface level. Detected. When the increase in the developer is detected, the control means 100 controls the drive motor (not shown) to switch the rotation direction so that the stirring screws 46 and 47 are rotated in the direction opposite to that during normal development. By this control, the agitating screw 47 is rotated so as to feed the developer in the direction opposite to the normal developer conveying direction, and the developer is supplied from the opening 40b into the developer discharge housing 41B of the developer deterioration state detecting device 410. Will be dropped.

  FIG. 3 is a schematic cross-sectional view for explaining the configuration of the first embodiment of the developer deterioration state detecting device 410 according to the present invention. FIG. 3A is a diagram for explaining a connection configuration between the developer deterioration state detecting device 410 and the developing device 4, and is also a sectional view showing a YY section of the developing device 4 shown in FIG. FIG. 3B is a diagram for explaining the overall configuration of the developer deterioration state detecting device 410, and is also a cross-sectional view showing the XX cross section of FIG.

  The first embodiment of the developer deterioration state detection apparatus 410 according to the present invention includes a developer discharge housing 41B, a discharge screw 49, a developer discharge member 50, a developer accumulation platform 51, a discharged developer storage container 52, And laser distance meters LM1 and LM2 as the deposition state detecting means.

  The stirring screw 47 has a shape protruding outward toward the upstream side of the developer conveying direction of the stirring screw 47 located outside the developing device 4, and the protruding portion of the stirring screw 47 is formed in the developing device housing 40. It is surrounded by the cylindrical cover 40a which makes a part. An opening 40b for dropping the developer downward is provided in the lower part of the cylindrical cover 40a.

  The developer carrying-out means according to the present invention includes a developer carrying-out housing 41B disposed below the aforementioned opening 40b, a carrying-out screw 49 incorporated in the developer carrying-out housing 41B, and the like. The developer carrying-out housing 41B is connected to the developing device 4 at a position near the opening 40b of the cylindrical cover 40a, and has a cylindrical cover portion 41Ba. The cylindrical cover portion 41Ba surrounds the outer periphery of the unloading screw 49 that unloads the developer from the developing device 4 in the horizontal direction. An opening 41Bb that opens in the longitudinal direction along the developer unloading direction of the unloading screw 49 is formed in the lower portion of the cylindrical cover portion 41Ba on the downstream side in the developer unloading direction of the unloading screw 49. The unloading screw 49 is connected to a drive motor (not shown) and rotates to convey the developer received from the opening 40b in the cylindrical cover portion 41Ba in the developer unloading direction and drop downward from the opening 41Bb. Let

  A developer discharge member 50 as a developer discharge port according to the present invention is a member having upper and lower openings, and has a funnel shape with a wide upper opening (upper) and a lower lower opening (lower) 50a. It is formed and disposed on a carry-out path located below the opening 41Bb. The upper opening (upper) of the developer discharging member 50 is larger than the size of the opening 41Bb so that the developer falling from the opening 41Bb of the cylindrical cover 41Ba does not spill out from the developer discharging member 50. Is formed.

  In the present embodiment, the developer accumulation platform 51 is disposed horizontally directly below the developer discharge member 50 with the developer placement surface facing up. The center of the developer stack 51 and the center of the opening (lower) 50a of the developer discharge member 50 are located on the same vertical line. In the present embodiment, the developer deposit base 51 is made of a disk-shaped member having a diameter of approximately 20 mm. A pair of left and right rotating shafts 51a extending in the diameter direction is fixed at the center position in the thickness direction of the outer periphery of the disk-shaped member of the developer accumulation platform 51, and the developer accumulation platform 51 is connected to the developer deterioration state detection device 410. And hold it freely. The developer deposition stand 51 is provided with a stopper member (not shown) so that when depositing the developer G on the developer deposition stand 51, the developer deposition stand 51 stops at a horizontal position. The rotation shaft 51a is connected to a drive motor (not shown) that drives and rotates the rotation shaft 51a via a gear (not shown). The developer deposition table 51 is rotatably held, so that the developer G is deposited on the developer deposition table 51 in a state where the developer deposition table 51 is held horizontally, and the developer G is deposited in a state where it is rotated at a right angle or more. The developer G can be released downward. A discharged developer storage container 52 that stores the developer G for which the detection of the developer accumulation state has been completed is disposed below the developer accumulation platform 51.

  The laser distance meters LM1 and LM2 serving as the accumulation state detecting means in the first embodiment are disposed in the vicinity of the opening (lower) 50a of the developer discharge member 50 located above the developer accumulation stand 51. The laser distance meter LM2 is configured such that the position of the irradiated laser beam L1 is positioned at the laser distance so that the position of the irradiated laser beam L2 is a predetermined distance from the outer periphery of the developer deposition stand 51. They are arranged so as to be further inside by a predetermined distance from the total LM2. Two distance data measured by the laser distance meter LM1 and the laser distance meter LM2 are sent to the control means 100 as an electrical signal. In the memory built in the control means 100, a calculation formula for calculating the repose angle θ from the difference between the two distance data is stored as a program in advance, and the repose angle θ is calculated by inputting an electric signal of the distance data. Is done.

  Next, in the first embodiment, the operation from when the developer G is carried out from the inside of the developing device 4 until it is deposited on the developer depositing stand 51 and the operation of each part of the device will be described.

  The developer G is carried out to the developer deterioration state detecting device 410 periodically or when the deterioration of the developer is detected. The stirring screw 47 of the developing device 4 is turned on by a command from the control means 100. Reverse rotation is performed and unloading is started.

  In FIG. 3, the developer G in the developing device housing 40 is dropped into the developer carrying housing 41B of the developer deterioration state detecting device 410 from the opening 40b of the cylindrical cover 40a by the reverse rotation of the stirring screw 47. The The developer G dropped into the developer carrying-out housing 41B is conveyed by the carrying-out screw 49 toward the opening 41Bb through the cylindrical cover portion 41Ba, and downward from the opening 41Bb through the developer discharging member 50. The developer is dropped and deposited on the developer depositing stage 51. The developer G deposited on the developer deposition platform 51 is measured for the distance to the slope of the developer G deposited by the laser distance meters LM1 and LM2, and the repose angle θ is calculated. Thereafter, the developer depositing stage 51 is rotated around the rotation shaft 51a, and the developer G on the developer depositing stage 51 is dropped into the discharged developer storage container 52 and stored.

  When the developer in the developing device 4 is discharged by the above series of operations and the interface level detecting means detects that the developer G has been reduced to the standard level, the control means 100 controls the stirring screws 46 and 47. Stop reverse operation and then return to normal rotation.

  In the first embodiment, the height of the developer G deposited on the developer deposition platform 51 is always developed at the point measured by the laser distance meter LM1 rather than the point measured by the laser distance meter LM2. Since it is close to the center position of the agent deposition stand 51, it is at a high position. In order for the measurement in the present embodiment to be performed correctly, it is premised that the developer is deposited at a point measured by the laser distance meter LM2. This is because if the amount of developer G deposited is small and developer deposition is not observed at the point measured by the laser distance meter LM2, the difference in the distance to the slope of the developer deposited by the laser distance meters LM1 and LM2 This is because the comparison cannot be made. As a more preferable state, the developer G to be accumulated overflows from the developer accumulation stand 51 and falls to the discharged developer storage container 52 below. In this state, the slopes of the peaks of the developer G deposited on the developer deposition platform 51 are formed at stable and constant positions.

  In the present embodiment, the developer G is conveyed into the developer deterioration state detecting device 410 from the opening 40b of the cylindrical cover portion 41Ba by the reverse rotation of the stirring screw 47 of the developing device 4. However, it is good also as a structure which does not rotate the stirring screw 47 reversely. For example, the opening 40b is provided on the downstream side of the stirring screw 46, and a shutter member that can be opened and closed is provided in the opening 40b, and the shutter member is opened and closed as necessary. It is a configuration. The opening and closing of the shutter member in this configuration is controlled based on information such as the amount of developer G supplied from the developer supply device and the accumulation state of the developer G.

  Further, a small amount of developer G may be dropped from the opening 40b constantly or periodically without providing a shutter member in the opening 40b of the developing device 4 having the above-described configuration. At this time, the carrier C is replenished from the carrier replenishing device 70 by an amount corresponding to the amount of developer G discharged.

  According to the first embodiment of the developer deterioration state detecting device 410 according to the present invention, the repose angle θ can be easily obtained from the deposition of the developer G discharged from the developing device 4 on the developer depositing stand 51, and It is possible to measure accurately and to detect the deterioration state from the angle of repose θ and to take measures. The relationship between the angle of repose θ and the deterioration state will be described in the explanation of the experimental results described later.

  FIG. 4 is a schematic configuration diagram for explaining the configuration of the second embodiment of the developer deterioration state detecting device 410 according to the present invention. The configuration of the second embodiment is similar to the configuration of the first embodiment, and the members having the same functions are denoted by the same reference numerals, so the description thereof is omitted, and only different configurations are described. To do. The difference between the configuration of the second embodiment and the configuration of the first embodiment is the difference in the developer G accumulation state detection means. That is, the deposition state detection means is the laser distance meters LM1 and LM2 in the first embodiment, but is the mass sensor WM in the second embodiment. That is, in the second embodiment, by calculating the mass of the developer G deposited on the developer deposition stand 51, the volume and the repose angle θ on the developer deposition stand 51 can be calculated. Fluidity and deterioration state can be detected.

  In FIG. 4, reference numeral WM denotes a mass sensor as a deposition state detection unit that measures the mass of the developer G deposited on the developer deposition table 51. Since the area of the developer depositing stage 51 is constant, when the developer G is deposited up to the outer peripheral edge of the developer depositing stage 51, the volume and mass of the developer change according to the angle of repose θ. To do. Therefore, the angle of repose θ is calculated by measuring the mass of the developer, and the fluidity and deterioration state of the developer G can be detected.

  In the second embodiment, it is a necessary condition that the developer G is deposited up to the outer peripheral edge of the developer deposition table 51, and a more desirable state is that the developer G to be deposited is removed from the developer deposition table 51. In this state, it overflows and falls to the discharged developer storage container 52 below.

  According to the second embodiment of the developer deterioration state detection apparatus 410 according to the present invention, the repose angle θ can be easily and accurately measured with a simple configuration, and the deterioration state is determined from the repose angle θ. Can be estimated and linked to countermeasures.

  FIG. 5 is a schematic configuration diagram for explaining the configuration of the third embodiment of the developer deterioration state detecting device 410 according to the present invention. The configuration of the third embodiment is similar to the configuration of the first embodiment, and the members having the same functions are denoted by the same reference numerals, so that the description thereof is omitted, and only different configurations are described. To do. The difference between the configuration of the third embodiment and the configuration of the first embodiment is the difference in the developer G accumulation state detection means. That is, the deposition state detecting means is the laser distance meters LM1 and LM2 in the first embodiment, but the magnetic permeability sensors MM1 and MM2 in the third embodiment. That is, in the third embodiment, by detecting the magnetic permeability of the developer G deposited on the developer deposition stand 51 at two different locations, the deposition height of the developer G at two locations is determined, and the rest is rested. The angle θ is calculated, and the fluidity and deterioration state of the developer G are detected.

  In FIG. 5, reference numerals MM1 and MM2 are magnetic permeability sensors as accumulation state detecting means for calculating the magnetic permeability of the developer G deposited on the developer accumulation stand 51, and two magnetic permeability sensors MM1 and MM2 are used. Are disposed on the lower surface of the developer depositing stage 51. The positions of the two magnetic permeability sensors MM1 and MM2 are such that the magnetic permeability sensor MM1 is positioned at a predetermined distance from the outer periphery of the developer depositing base 51 so that the magnetic permeability sensor MM1 is positioned at the magnetic permeability sensor MM2. Further, they are arranged so as to be inside a predetermined distance. Two magnetic permeability data measured by the two magnetic permeability sensors MM1 and MM2 are sent to the control means 100 as electric signals. A memory (not shown) built in the control unit 100 stores a calculation formula as a program for calculating the deposition height of the developer G from the difference between the two magnetic permeability data and calculating the repose angle θ. The angle of repose θ is calculated by inputting an electrical signal of permeability data.

  In the third embodiment, similarly to the first embodiment, it is premised that developer is deposited at a point measured by the magnetic permeability sensor MM2, and desirably, the developer G is placed on the developer deposition table. It is in a state where it overflows from 51 and falls downward.

  According to the third embodiment of the developer deterioration state detection apparatus 410 according to the present invention, the repose angle θ can be easily measured with a simple configuration, and the deterioration state is estimated from the repose angle θ. It can lead to countermeasures.

  FIG. 6 is a schematic configuration diagram for explaining the configuration of the fourth embodiment of the developer deterioration state detecting device 410 according to the present invention. The configuration of the fourth embodiment is similar to the configuration of the first embodiment, and the members having the same functions are denoted by the same reference numerals, so that the description thereof is omitted, and only different configurations are described. To do. The difference between the configuration of the fourth embodiment and the configuration of the first embodiment is the difference in the developer G accumulation state detection means. That is, the deposition state detection means is the laser distance meters LM1 and LM2 in the first embodiment, but in the fourth embodiment, it is composed of the deposition developer contact plate TB and the deposition angle detection encoder EC. is there. That is, the accumulated developer contact plate TB directly contacts the inclined surface of the deposited developer G to detect the inclination angle thereof, and the accumulated angle detection encoder EC detects the inclination angle of the accumulated developer contact plate TB ( The repose angle θ) is detected.

  The accumulation state detection means according to the present invention comprises a accumulation developer contact plate TB and an accumulation angle detection encoder EC.

  In FIG. 6, the accumulated developer contact plate TB is integrally held by the support arm SA. The support arm SA is formed in a V shape, one end is fixed to the back of the developer contact surface of the deposited developer contact plate TB, and the shaft SAj attached in the vicinity of the other end It fits into a bearing member (not shown) attached to the notch on the side surface of the agent depositing stand 51. That is, the support arm SA is rotatably held with respect to the developer depositing base 51 by fitting the bearing member and the shaft SAj. In addition, a deposition angle detection encoder EC is connected to the shaft SAj so that the tilt angle of the deposition developer contact plate TB held integrally with the support arm SA can be detected.

  That is, in the fourth embodiment, the deposited developer abutting plate TB is brought into direct contact with the slope of the developer G deposited on the developer deposition stand 51, and the angle is detected by the deposition angle detection encoder EC. The inclination angle (rest angle θ) of the deposition of the agent G is detected, and the fluidity and the deterioration state of the developer G are detected.

  In the fourth embodiment, as in the second embodiment, it is a necessary condition that the developer G is deposited up to the outer peripheral edge of the developer deposition stand 51, and the more desirable state is the development to be deposited. In this state, the developer G overflows from the developer stack 51 and falls to the discharged developer storage container 52 below.

  According to the fourth embodiment of the developer deterioration state detection apparatus 410 according to the present invention, the repose angle θ can be easily and accurately measured with a simple configuration, and the deterioration state is estimated. It can lead to countermeasures.

  In the first to fourth embodiments, the toner replenishing device 60 and the carrier replenishing device 70 supply the toner T and the carrier C, respectively. However, a predetermined toner ratio is supplied to one developer replenishing device. The two-component developer may be loaded and a certain amount of the developer may be supplied. Further, instead of supplying a fixed amount of the two-component developer, an arbitrary amount of the two-component developer is supplied, and when it is detected by the interface level detection means that the predetermined amount of the two-component developer is supplied, A configuration in which the supply is stopped is also possible.

  When the two-component developer in the developing device 4 is to be completely discharged for the purpose of replacement after tens of thousands of prints have been imaged, the user selects and sets the developer discharge mode. Then, the developer is discharged via the control means 100. The control means 100 calls a developer discharge program from the built-in memory and discharges the two-component developer stored in the developing device 4. In the present embodiment, the control means 100 causes the transport drive motor that drives the agitation screws 46 and 47 to perform a reverse operation, and simultaneously starts the rotation of the unloading screw 49. Due to the reverse rotation of the agitating screw 47, the developer G in the developing device housing 40 falls from the opening 40b, is transported by the unloading screw 49, further falls from the developer discharge member 50, and is deposited on the developer deposition stand 51. Thereafter, the developer is stored in the discharged developer storage container 52.

  Control for the embodiment of the developing device described above is performed by a monochrome printer, and in a color printer, control is performed independently for each of the developing devices of a plurality of colors.

  Further, the developing device 4 in the present embodiment has been described with respect to a configuration in which a two-component developer is used, but the present invention can also be applied to a developing device configured to use a one-component developer.

  So far, the developer deterioration state detecting device of the present invention has been described, but the present invention is performed by using the developer deterioration state detecting device of the present embodiment, and developer deterioration that detects the developer deterioration state is performed. It can also be applied as a state detection method.

  Further, the developer deterioration state detecting device of the present invention has been described so far. Hereinafter, the image forming apparatus main body A provided with the image forming condition changing means according to the present invention when the developer deterioration state is detected will be described. This will be described with reference to the block diagram of FIG.

  As the image forming apparatus main body A provided with the image countermeasure means when the repose angle θ is detected by the accumulation state detecting means of the present invention and the deterioration state of the developer is detected, the developer supply devices 60 and 70 are controlled. There is a first embodiment and a second embodiment for controlling the developing bias changing means BH.

  FIG. 7 is a block diagram for explaining the control of the control means 100 for controlling the operations of the first and second embodiments of the image forming apparatus main body A according to the present invention.

  In FIG. 7, the control unit 100 determines the developer based on the deterioration state detection unit according to the present invention in accordance with the detection result of the accumulation state detection unit in the first to fourth embodiments of the developer deterioration state detection device 410. Judge the deterioration state.

  The deterioration state detection means here is means for determining the deterioration state of the developer by the control means 100 in accordance with the detection result of the accumulation state detection means, and specifically, the repose angle θ of the accumulated developer and This is a program stored in a memory by comparing the deterioration state of the developer. This program is experimentally programmed as a means for comparing and correlating the repose angle θ of the deposited developer with the deterioration state of the developer, and determining the deterioration state of the developer based on the repose angle θ. Is stored in advance in a memory built in the.

  The control unit 100 determines the deterioration state by the deterioration state detection unit according to the detection result of the accumulation state detection unit, and controls the operation of the developer supply devices 60 and 70 or the development bias change unit BH. The deposition state detection means here is the laser distance meters LM1 and LM2 in the first embodiment, the mass sensor WM in the second embodiment, and the permeability sensors MM1 and MM2 in the third embodiment. In the fourth embodiment, the accumulated developer contact plate TB and the accumulated angle detection encoder EC are indicated.

  In the first embodiment of the image forming apparatus main body A corresponding to the deterioration of the developer according to the present invention, the operations of the developer replenishing devices 60 and 70 are controlled, and in the second embodiment of the image forming apparatus main body A. The operation of the developing bias changing means BH is controlled.

(One Embodiment of Image Forming Apparatus Main Body A)
In one embodiment of the image forming apparatus main body A according to the present invention, the image is determined by the deterioration state detection unit based on the detection result of the accumulation state detection unit in the first to fourth embodiments of the developer deterioration state detection device 410. The operation of the developer supply devices 60 and 70 as the forming condition changing means is controlled. Specifically, for example, the carrier replenishing device 70 as one of the developer replenishing devices replenishes the carrier C into the developing device 4 based on the integrated number of copies as described with reference to FIG. The actual developer replenishment amount is controlled according to the toner concentration of the developer to be used and the value of the angle of repose θ. The numerical values of the embodiment will be described in the section of Embodiment 1 described later.

  According to the first embodiment of the image forming apparatus main body A according to the present invention, the developer replacement amount is controlled in accordance with the deterioration state of the developer, so that the developer can always be kept in a normal state.

(Another embodiment of image forming apparatus main body A)
In another embodiment of the image forming apparatus main body A according to the present invention, the image is determined by the deterioration state detection unit based on the detection result of the accumulation state detection unit in the first to fourth embodiments of the developer deterioration state detection device 410. The operation of the developing bias changing means BH as the forming condition changing means is controlled. Specifically, the variable frequency AC bias power supply AC1 as one of the developing bias changing means BH is configured to have a variable frequency as described with reference to FIG. The actual control of the frequency of the AC bias power supply AC1 is performed according to the toner concentration of the developer to be used and the value of the angle of repose θ. The numerical values of the embodiment will be described in the section of the embodiment 2 described later. .

  According to the second embodiment of the image forming apparatus main body A according to the present invention, even when the developer approaches a deteriorated state, the developing bias changing unit BH as the image forming condition changing unit is controlled to be stable. Image formation can be performed.

  The image forming apparatus provided with the developer deterioration state detection device of the present invention has been described so far, but the present invention detects the developer deterioration state performed using the image forming apparatus of the present embodiment. It can also be applied as a developer deterioration state detection method.

  The inventors conducted an experiment in which the first to fourth embodiments of the developer deterioration state detection apparatus 410 according to the present invention were mounted on the image forming apparatus main body A to examine the influence on the output image. The contents and results of the experiments for Examples 1 and 2 and the comparative example will be described below.

(Common conditions)
Common conditions for the experiment are as follows.

1. Environmental conditions: Temperature 30 ° C, humidity 80% RH
2. Photosensitive drum 1 diameter: 60 mm
3. Developing roller 42 diameter (sleeve outer diameter): 25 mm
4). Developing roller 42 circumferential speed: 720 mm / s (in the developing region, the sleeve surface of the developing roller 42 and the surface of the photosensitive drum 1 move in the opposite direction)
5. Gap between the developing roller 42 and the photosensitive drum 1: 0.3 mm
6). Developer transport amount on the surface of the developing roller 42: 220 g / m ²
7). Image forming apparatus: monochrome image forming apparatus (number of printed sheets: 80 sheets / min, process speed: 400 mm / s, see FIG. 1)
8). Toner average particle size: 6.5 μm
9. Carrier average particle size: 33 μm
10. Toner concentration: 7% by mass
11. Developer amount in the developing device 4: 600 g
12 Control of carrier replenishment amount according to printing rate (see Table 1)
The correction of increasing the carrier replenishment amount as a countermeasure against developer deterioration is greatly influenced by the print rate i of various output images, and is not directly related to the control of the image forming conditions of the present invention. Therefore, the control of the carrier replenishment amount according to the printing rate i shown in Table 1 is treated as a precondition common to both the example and the comparative example in order to remove the factor of developer deterioration due to the printing rate i.

  Table 1 shows preparatory work that is a precondition for the experiment, in order to change the reference carrier replenishment amount α serving as a reference in accordance with the print rate i of the output image, and to reduce the variation in carrier deterioration due to the print rate i. These are items uniformly applied to all of Examples 1 and 2 and Comparative Example 1. The printing rate i represents an average printing rate for every 1000 sheets printed. The reason for increasing the reference carrier replenishment amount α in accordance with the printing rate i has been found by experiments that the carrier deterioration rate increases as the printing rate i increases. In order to suppress the carrier deterioration rate, the printing rate This is because the carrier replacement amount is increased according to i.

(Individual conditions)
The individual conditions for the experiment are as follows.

Example 1
1. Developer deterioration state detection device 410: First embodiment (see FIG. 3)
2. Opening diameter of the opening (lower) of the developer discharging member 50: 5 to 10 mm
3. Developer deposit base 51: Disc 20 mm in diameter (non-magnetic member)
4). Correction of the amount of carrier replenishment according to the angle of repose θ (see Table 2)
5.4 Image Forming Apparatus Main Body A Incorporating Control of Correction of Carrier Replenishment Amount of Four Items
In the first embodiment, as shown in Table 2, the range of the repose angle θ is classified into four stages from the first stage to the fourth stage according to the toner density, and a certain amount of the carrier C is determined according to each repose angle θ. Correction to be added. The reason for this correction is that if the angle of repose θ is large, it is determined that the deterioration of the developer has progressed, and the replacement amount of the carrier C is increased.

  In Table 2, the symbol β represents the carrier correction amount. When the range of the repose angle θ is in the first stage, the carrier correction amount β is reduced in the value of the reference carrier replenishment amount α in Table 1 because the flowability of the developer G is high and the deterioration rate of the carrier C is slow. May be. Therefore, in the first stage of the range of the repose angle θ, the carrier correction amount β is set to −0.5 g, and 0.5 g is subtracted from the value of the reference carrier supply amount α.

  Similarly, when the range of the repose angle θ is in the second stage, the fluidity of the developer G is in an appropriate state, and the deterioration rate of the carrier C is normal. The value may be the same value. Therefore, in the second stage in the range of the repose angle θ, the carrier correction amount β is set to 0 g, and the value of the reference carrier supply amount α is not corrected.

  Similarly, when the range of the repose angle θ is in the third stage, the fluidity of the developer G is slightly low and the deterioration rate of the carrier C is slightly high. The amount α is increased by 0.5 g. Furthermore, when the range of the repose angle θ is in the fourth stage, the fluidity of the developer G is low and the deterioration rate of the carrier C is fast, so the value of the reference carrier replenishment amount α is increased by 1.0 g. .

(Example 2)
1. The specifications of the developer deterioration state detecting device 410, the opening (lower) of the developer discharging member 50, and the developer depositing stage 51 are the same as the conditions described in the first to third items of the first embodiment. Is omitted.

2. Correction of development bias frequency according to angle of repose θ (see Table 3)
Image forming apparatus main body A incorporating control of correction of development bias frequency of item 3.2
The difference between the second embodiment and the first embodiment is a correction method for the carrier replenishment amount according to the angle of repose θ. In the first embodiment, the correction to the reference carrier replenishment amount α corresponding to the angle of repose θ is corrected by the carrier correction amount β. In the second embodiment, the development bias frequency shown in Table 3 is changed to the development bias changing means. The image forming conditions are corrected by changing with BH. That is, the developing bias changing means BH in the second embodiment is composed of a variable frequency AC bias power supply AC1 and a DC bias power supply E1, and the image forming conditions are changed by changing the frequency of the AC bias power supply AC1. Yes.

  In Table 3, as in Table 2, the range of the repose angle θ is classified into four stages from the first stage to the fourth stage for each toner concentration, and the frequency of the AC bias power supply AC1 is changed according to each repose angle θ. Correction to make. That is, the frequency is set to 5 kHz in the first stage of the range of the repose angle θ, 6 kHz in the second stage, 7 kHz in the third stage, and 8 kHz in the fourth stage.

(Comparative example)
1. The specifications of the developer deterioration state detecting device 410, the opening (lower) of the developer discharging member 50, and the developer depositing stage 51 are the same as the conditions described in the first to third items of the first embodiment. Is omitted.

  2. The image forming apparatus main body A does not perform the correction by the carrier correction amount β in the first embodiment (Table 2) or the correction by the AC bias frequency in the second embodiment (Table 3), and does not perform the carrier supply amount according to the printing rate i. Only the control (Table 1) is performed.

  Table 4 shows the results of experiments in which the angle of repose θ was measured and the image quality was evaluated using Examples 1 and 2 and a comparative example.

  In Table 4, the image quality in the evaluation item column is the output image output rate is changed to 5%, 10%, 20%, 35%, 50% for every 10,000 prints, and the image is output 50,000 prints. The image unevenness was evaluated by the internal standard chart of solid black and halftone every time. The symbol indicating the evaluation of the image quality represents the evaluation result performed based on the in-house judgment standard. The pass level is indicated by ◯, the reject level is indicated by ×, and the non-defective product limit level is indicated by △.

  From the results shown in Table 4, in Comparative Example 1, the repose angle θ is 37 ° to 39 °, and there is a quality limit of the image quality. The image quality was also rejected. On the other hand, in Example 2, the number of prints is approximately 200,000 prints, and the angle of repose θ reaches 37 °. It became a non-defective product limit. In Example 1, the repose angle θ was about 33 ° even when 300,000 prints were made, and the image quality was good.

  From these results, the present inventors have found that there is a risk that the developer is in a deteriorated state when the angle of repose θ exceeds approximately 37 °, and the angle of repose θ according to the configuration of the present invention. It was confirmed that the deterioration of the developer can be suppressed by controlling the value of and improving the fluidity of the developer. Further, from the results of Examples 1 and 2 and Comparative Example 1, even if the developer is deteriorated, the image quality is improved by controlling the developing bias condition and the developer supply amount as the image forming condition changing means of the present invention. That you can keep in.

  Furthermore, the present inventors also performed the same experiment for the second to fourth embodiments of the developer deterioration state detection apparatus 410 according to the present invention, but obtained almost the same results as those of the first embodiment. It was. About the 2nd-4th experimental result, since it is similar to the experimental result of 1st Embodiment, description is abbreviate | omitted.

  FIG. 8 is a graph showing the relationship between the angle of repose θ and the number of printed sheets in Table 4. In Table 4, the horizontal axis represents the number of printed sheets and the vertical axis represents the angle of repose. Symbol a represents a graph of Example 1 (solid line), b represents a graph of Example 2 (broken line), and c represents a graph of Comparative Example 1 (dashed line).

  By comparing FIG. 8 with Table 4, it can be seen that the quality limit of the image quality of the output image is in the vicinity of the line of Example 2 or Comparative Example 1 in which the number of printed sheets is 200,000 to 300,000.

DESCRIPTION OF SYMBOLS 1 Photosensitive drum 4 Developing apparatus 40 Developing apparatus housing 40a Cylindrical cover 40b Opening part 41A Top plate 41B Developer carrying-out housing (Developer carrying-out means)
41Ba Cylindrical cover part 41Bb Opening part 42 Developing roller (developer carrier)
46, 47 Stirring screw 49 Unloading screw (developer unloading means)
50 Developer discharge member 50a Opening (bottom)
51 Developer Stacking Stage 51a Rotating Shaft 52 Discharged Developer Storage Container 60 Toner Supply Device (Developer Supply Device)
70 Carrier supply device (developer supply device)
DESCRIPTION OF SYMBOLS 100 Control means 410 Developer deterioration state detection apparatus A Image forming apparatus main body AC1 AC bias power supply BH Development bias change means C Carrier E1 DC bias power supply EC Deposition angle detection encoder (deposition state detection means)
G Developer H (C) Carrier supply port H (T) Toner supply port i Printing rate LM1, LM2 Laser distance meter (deposition state detection means)
MM1, MM2 Permeability sensor (deposition state detection means)
P paper SA support arm T toner TB accumulated developer contact plate (accumulated state detection means)
WM Mass sensor α Reference carrier replenishment amount β Carrier correction amount θ Repose angle

Claims (10)

Developer carrying means for carrying out the developer stored in the developing device from the developing device;
A developer discharge port that is disposed on the developer carry-out path of the developer carry-out means and causes the developer carried out by the developer carry-out means to fall downward;
A developer depositing stage disposed below the developer discharge port and depositing the developer falling from the developer discharge port;
A deposition state detecting means for detecting a deposition state of the developer deposited on the developer deposition table;
A deterioration state detecting means for detecting the deterioration state of the developer from the developer deposition state;
A developer deterioration state detecting device characterized by comprising:   The developer deterioration state detection apparatus according to claim 1, wherein the accumulation state detection unit measures an angle of repose of the developer deposited on the developer accumulation stand.   The developer deterioration state detection apparatus according to claim 1, wherein the accumulation state detection unit measures a mass of the developer deposited on the developer accumulation stand.   The developer deterioration state detection apparatus according to claim 1, wherein the accumulation state detection unit measures a magnetic permeability of the developer deposited on the developer accumulation stand.   An image forming apparatus comprising the developer deterioration state detecting device according to claim 1. Image forming condition changing means for changing image forming conditions;
Control means for controlling the operation of the image forming condition changing means,
The image forming apparatus according to claim 5, wherein the control unit controls an operation of the image forming condition changing unit according to a detection result by the deterioration state detecting unit. A developer supply device for supplying the developer;
Control means for controlling the operation of the developer supply device,
The image forming condition changing means is a developer replenishing device that replenishes the developing device with developer.
The image forming apparatus according to claim 6, wherein the control unit controls a developer replenishment amount by the developer replenishing device in accordance with a detection result by the deterioration state detection unit. The image forming condition changing unit changes a developing bias condition applied to the developing device,
The image forming apparatus according to claim 6, wherein the control unit changes a developing bias condition applied to the developing device according to a detection result by the deterioration state detecting unit.   5. A developer deterioration characterized in that a deterioration state is detected from a state of accumulation of the developer deposited on the developer depositing stage using the developer deterioration state detecting device according to claim 1. State detection method.   9. A developer deterioration state detection method, comprising: detecting a deterioration state from a developer accumulation state deposited on the developer deposition table using the image forming apparatus according to claim 5. .

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