JP2008310111A - Image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rotary development type image forming device for preventing effectively initial toner installation error even when deviation or blocking of friction preventive toner occurs in a developing device. <P>SOLUTION: This rotary type color image forming device is provided with a developing unit 4 including cartridge type developing devices 4a, 4b, 4c, 4d having the developing devices integrated with toner containers for respective yellow, magenta, cyan and black colors, and forms a toner image of each color by moving rotationally moving sequentially the developing devices 4a, 4b, 4c, 4d to a position facing a photoreceptor drum 1, and by depositing toner to an electrostatic latent image on the photoreceptor drum 1. The rotary type color image forming device executes a toner installation mode in which the developing unit 4 is rotated and the developing devices 4a, 4b, 4c, 4d after that are driven in one cycle before the first toner installation from a cartridge 5. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an image forming apparatus using an electrophotographic process such as a copying machine, a printer, or a facsimile machine, and more particularly to a method for initially installing toner in a rotary developing unit.

  Development devices used in image forming apparatuses such as copiers, printers, facsimiles, and composite machines using electrophotography use a two-component development system that uses toner and carrier as a developer, or a carrier. A one-component developing system using only toner is known.

  In the one-component development method, the toner contained in the main body of the developing device is sent to the surface of the developing roller by a supply roller, and a regulating member is pressed against the developing roller to regulate the amount of toner and frictionally charge, and the developing roller is rotated. The electrostatic latent image formed on the image carrier is developed by guiding the toner to the development area facing the image carrier, and the toner remaining on the surface of the development roller is separated from the surface of the development roller by the supply roller and newly developed. The toner is supplied to the developing roller. In this method, the toner concentration can be easily controlled, and mixing and stirring with carrier particles is unnecessary, so that the developing device can be easily downsized, and the developer does not contain magnetic powder, so that color superposition is possible. Therefore, it can be said that the developing system is most suitable for a small color printer.

  As a color image forming apparatus using this one-component developing method, a cartridge type developing device corresponding to the number of colors to be used is supported on a cylindrical rotary rack configured to be rotatable, and development of a toner supply unit corresponding to each color is performed. There has been developed an image forming apparatus including a rotary developing unit in which rollers are sequentially opposed to an image carrier.

  By the way, in the one-component developing system, since the regulating member and the supply roller are brought into contact with the developing roller, it is necessary to prevent the occurrence of damage due to friction between the members during the initial driving. For this reason, normally, at the time of shipment of the apparatus main body or the developing unit, an amount of toner capable of forming a toner layer on the developing roller (hereinafter referred to as initial filling toner) is filled in advance.

  In the case of a type in which toner is additionally supplied to the developing device, it is necessary to supply a predetermined amount of toner (initial toner installation) to each color developing device in the developing unit when the device is initially driven. In this case, the toner amount detecting means provided in the developing device detects the amount of toner filled in the developing device, and determines whether or not toner replenishment is necessary or not.

  However, deviation or blocking of the initially filled toner in the developing device may occur depending on the transportation state or storage environment at the time of shipment of the apparatus main body or the developing unit. As a result, there is a problem that erroneous detection of the toner amount detecting means is likely to occur at the time of initial toner installation, resulting in toner replenishment failure such as overfilling or underfilling.

As a method of preventing toner blocking in a rotary developing unit, for example, in Patent Document 1, after a predetermined number of single-color printings, the rotary developing unit is rotated a certain number of times, thereby blocking toner or heat. A method for preventing degradation is disclosed.
JP-A-10-26862

  However, in the method of Patent Document 1, although deterioration of the toner in the developing device that is not used for a long time during the printing operation can be prevented, it is not possible to prevent the deviation and blocking of the initial filling toner after transportation of the device main body, This is not an appropriate method for preventing the occurrence of defective toner replenishment during initial installation.

  In view of the above problems, the present invention provides a rotary developing type image forming apparatus that can effectively prevent the occurrence of initial toner installation failure even when the initial filling toner is offset or blocked in the developing device. The purpose is to provide.

  In order to achieve the above object, the present invention provides a rotary developing unit in which a plurality of developing devices containing a developer are arranged along the circumferential direction of a rotating body, and a developing device in the developing unit. An image for developing an electrostatic latent image on the image carrier by moving any one of the developing devices to a position facing the image carrier by rotation of the developing unit. In the forming apparatus, each developing device is preliminarily filled with a predetermined amount of toner, and before the first toner replenishing operation by the toner replenishing means, the developing unit is rotated and the rotational operation is continued. The toner installation mode in which the driving of each developing device is one cycle is executed at least once.

  According to the present invention, in the image forming apparatus configured as described above, the rotation speed of the developing unit in the toner installation mode is higher than the rotation speed at the time of image formation.

  According to the present invention, in the image forming apparatus configured as described above, the number of rotations of the developing unit in one cycle of the toner installation mode is set to 2 times or less, and the driving time of each developing device is set to 5 seconds to 10 seconds. The number of repetitions is 4 or less.

  According to the first configuration of the present invention, only the developing device is obtained by executing the toner installation mode in which the rotation operation of the developing unit and the driving of each developing device are used together to disperse the initial filling toner in the developing device. The continuous drive time of the developing device can be shortened compared with the case where the initial filling toner is dispersed by driving, and the toner in the developing device circulates due to the rotation operation of the developing unit, and mechanical stress on some toners Concentration is suppressed. Further, the number of unit rotations can be reduced as compared with the case where only the developing unit is rotated to disperse the initial filling toner. Accordingly, it is possible to effectively prevent the occurrence of toner replenishment failure at the time of initial installation while simultaneously suppressing the deterioration of the toner accompanying the continuous driving of the developing device and the generation of noise accompanying the rotation of the developing unit.

  According to the second configuration of the present invention, in the image forming apparatus having the first configuration, the developing unit is rotated at a rotational speed higher than the rotational speed at the time of image formation in the toner installation mode. The toner in the apparatus can be stirred more efficiently, and the rotation time can be shortened.

  According to the third configuration of the present invention, in the image forming apparatus having the first or second configuration, the number of rotations of the development unit in one cycle of the toner installation mode is 2 times or less, and the drive time of each development device. Is set to 5 seconds or more and 10 seconds or less, and the number of cycle repetitions is set to 4 times or less, so that a sufficient toner dispersion effect can be obtained while suppressing noise caused by unit rotation and toner deterioration due to driving of the developing device. Necessary and sufficient execution conditions.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a side sectional view showing an internal structure of a rotary developing type color printer according to the present invention. In the color printer 100, when an image forming operation is performed, the photosensitive drum 1 that rotates counterclockwise in the drawing in the apparatus main body is uniformly charged by the charging unit 2, and is sent from a personal computer (not shown) or the like. An electrostatic latent image is formed on the photosensitive drum 1 by the laser beam from the exposure unit 3 based on the image data.

  A rotary developing unit 4 that supplies a developer (hereinafter referred to as toner) onto the photosensitive drum 1 is disposed in the vicinity of the photosensitive drum 1. The developing unit 4 includes cyan, magenta, yellow and black developing cartridges 4a, 4b, 4c and 4d in which a developing device and a toner container are integrated in a rotatable rotary rack at equal intervals in the circumferential direction. By sequentially rotating the developing cartridges 4a to 4d to a position facing the photosensitive drum 1 (hereinafter referred to as a home position), toner is attached to the electrostatic latent image on the photosensitive drum 1 and each color is changed. A toner image is formed. Toner supply (toner installation) to the developing cartridges 4 a to 4 d is performed from the toner cartridge 5. When the toner is replenished, the replenishment pipe 5a of the toner cartridge 5 extends to the position of the thick line in FIG.

  An intermediate transfer belt 6 onto which a toner image is transferred is disposed below the photosensitive drum 1 and is rotated clockwise in the figure by driving means (not shown) while contacting the photosensitive drum 1. A sheet made of dielectric resin is used for the intermediate transfer belt 6, and a belt in which both ends thereof are overlapped and joined to form an endless shape, or a belt without a seam (seamless) is used.

  When the user inputs a color image formation, the developing device 4a is placed at the home position, and a cyan toner image is formed on the photosensitive drum 1 at a predetermined timing. After an electric field is applied to the intermediate transfer belt 6 at a predetermined transfer voltage, a cyan toner image on the photosensitive drum 1 is transferred onto the intermediate transfer belt 6 by the primary transfer roller 7a. Thereafter, the toner remaining on the surface of the photosensitive drum 1 is removed by the cleaning unit 8, the developing unit 4 is rotated by a predetermined amount (90 ° here), and the developing device 4b is moved to the home position. A magenta toner image is formed on the photosensitive drum 1 and transferred onto the intermediate transfer belt 6.

  Thereafter, yellow and black toner images are transferred onto the intermediate transfer belt 6 by the photosensitive drum 1 in the same manner as described above. These four color images are formed with a predetermined positional relationship predetermined for forming a predetermined full-color image. Reference numeral 7 b denotes a secondary transfer roller positioned below the intermediate transfer belt 6.

  A sheet is fed from a sheet feeding mechanism 9 including a sheet feeding cassette 9a and a manual feed tray (stack bypass) 9b provided above the sheet toward the intermediate transfer belt 6 on which the toner image is formed as described above. The toner image formed on the surface of the intermediate transfer belt 6 is transferred onto the sheet by the secondary transfer roller 7b. Then, the sheet on which the toner image is transferred is conveyed along the sheet conveying path 12 to the fixing unit 13 having the fixing roller pair 13a to fix the toner image. The paper that has passed through the fixing unit 13 is distributed in the conveyance direction by a branching unit 14 that branches in a plurality of directions. When an image is formed only on one side of the sheet, the sheet is directly discharged onto the discharge tray 17 via the sheet conveyance path 15 and the discharge roller pair 16.

  On the other hand, when images are formed on both sides of the paper, the paper that has passed through the fixing unit 13 is switched in the transport direction downward by the feed roller 18 in the paper transport path 15 and then the image surface is directed upward at the branching unit 14. Then, the sheet is distributed to the sheet re-conveying path 19 and further re-conveyed to the secondary transfer roller 7b through the reverse roller 20 and the registration roller pair 11 with the image surface facing downward. The next image formed on the intermediate transfer belt 6 is transferred to the surface on which the sheet image is not formed by the secondary transfer roller 7b, conveyed to the fixing unit 13, and the toner image is fixed. The paper is discharged from the pair 16 onto the discharge tray 17.

  FIG. 2 is a side sectional view of the developing device of the present invention. In the following description, the configuration and operation of the developing device 4a opposite to the photosensitive drum 1 in FIG. 1 will be described. However, the configuration and operation of the developing devices 4b to 4d are basically the same, and the description is omitted. To do.

  As shown in FIG. 2, the developing device 4 a is provided with a toner stirring unit 21 in which toner is stored and a toner supply unit 22 to which toner is supplied from the toner stirring unit 21 in a resin-made developing container 20. ing. The toner stirring unit 21 and the toner supply unit 22 are partitioned by a boundary wall 23, and an opening 23 a is formed in the boundary wall 23. The openings 23 a are provided at a plurality of locations in the longitudinal direction (paper surface direction in the drawing) of the boundary wall 23, so that the toner can go back and forth between the toner stirring unit 21 and the toner supply unit 22.

  In the toner agitation unit 21, an agitation paddle 24 in which an agitation blade such as a PET film is attached to a rotation shaft is rotatably supported in a counterclockwise direction in FIG. The toner supply unit 22 faces a photosensitive drum (see FIG. 1) on which a latent image is formed and develops the latent image, and toner supply for supplying toner to the developing roller 25. A metal regulating member 27 and the like for regulating the toner layer thickness on the roller 26 and the developing roller 25 and charging the toner are provided.

  The toner layer on the developing roller 25 is regulated in layer thickness by a regulating member 27 (for example, a SUS foil having a thickness of 0.08 mm and regulated pressure = 25 N / m) and is triboelectrically charged. 1 is used for development of an electrostatic latent image on 1. A seal member 30 (for example, a conductive high molecular weight PE film is used as a gap between the developing roller 25 and the developing container 20 on the side opposite to the regulating member 27 and is backed up with a urethane sponge so as to uniformly contact the developing roller 25. The seal member 30 prevents toner leakage.

  In the developing container 20, the toner is normally stored up to the level of the one-dot chain line shown in FIG. 2. The toner amount in the developing container 20 is detected by a toner amount detection sensor 31. As the toner amount detection sensor 31, for example, a piezoelectric sensor, a light transmission type sensor, a magnetic permeability sensor that detects a change in magnetic permeability due to an increase in the amount of toner, or the like is used.

  Next, the developing process of the developing device will be described. The toner in the toner stirring unit 21 is sent to the toner supply unit 22 through the opening 23 a by the rotation of the stirring paddle 24. The toner sent to the toner supply unit 22 side is conveyed to the developing roller 25 by the toner supply roller 26, is regulated to a thin layer by the regulating member 27, is conveyed to the development nip portion, and is electrostatic latent image on the photosensitive drum 1. Develop. The toner that is not used for development and remains on the developing roller 25 passes through the seal member 30 and is then returned to the toner supply unit 22.

  As described above, each of the developing devices 4a to 4d is filled with an initial filling toner in order to reduce damage to members during initial driving. If a deviation or blocking of the initial filling toner occurs inside the apparatus, the toner additionally replenished may also be displaced, and the toner amount detection sensor 31 may erroneously detect the toner amount. For this reason, there is a problem in that the amount of toner to be installed for the first time varies, or it is determined that the installation is completed although the toner is not installed.

  Further, the initial filling toner is filled in a minimum amount necessary for preventing friction between members such as the developing roller 25, the toner supply roller 26, and the regulating member 27 at the time of initial driving, and therefore the amount thereof is very small. . For this reason, when each of the developing devices 4a to 4d is driven (aged) for a predetermined time to disperse the initial filling toner, a large mechanical stress is applied to a small amount of the initial filling toner, and the deterioration of the toner rapidly proceeds. As a result, image defects such as background fog are likely to occur in the output image immediately after the initial installation of the toner. Although a method of rotating the developing unit 4 to disperse the initial filling toner is also conceivable, as described later, in order to sufficiently disperse the initial filling toner, it is necessary to rotate the developing unit 4 several tens of times. The generation of noise associated with the rotation operation becomes a problem.

  Therefore, in the present invention, prior to the first toner installation from the toner cartridge 5 (see FIG. 1), the toner in which the rotation operation of the developing unit 4 and the subsequent driving of the developing devices 4a to 4d are one cycle. You are going to run install mode.

  By rotating the developing unit 4 before driving each of the developing devices 4a to 4d, the toner in each of the developing devices 4a to 4d is softly and sufficiently stirred, so that the toner can be removed without damaging the toner. It becomes possible to disperse, and the subsequent drive time of each of the developing devices 4a to 4d can be shortened to suppress toner deterioration. Further, since the number of rotations of the developing unit 4 can be reduced as compared with the method in which the initial filling toner is dispersed only by the rotation of the developing unit 4, noise associated with the rotation of the developing unit 4 is also reduced.

  Here, when the developing unit 4 is rotated, the developing unit 4 may be continuously rotated, or may be an intermittent rotation operation in which the rotation is temporarily stopped and the rotation is started again. When the intermittent rotation is performed, the toner in each of the developing devices 4a to 4d is lifted by the rotation of the developing unit 4, and when the rotation stops, the toner adhered to the inner wall is repeatedly broken down by gravity, so that the toner is more effective. To be stirred.

  In addition, if the rotation of the developing unit 4 is stopped at the same position every time in the intermittent rotation operation, for example, if it is stopped at a position different from the immediately preceding stop position, the toner collapsed in each of the developing devices 4a to 4d is collected. Since the position is changed, more efficient stirring is possible.

  The rotation speed of the developing unit 4 in the toner installation mode may be the same as the rotation speed when the developing devices 4a to 4d are switched during image formation, but the rotation speed is higher than that during image formation by providing a speed change mechanism. It is preferable that the toner in the developing devices 4a to 4d can be stirred more efficiently and the rotation time can be shortened.

  The number of rotations of the developing unit 4 in one cycle of the toner installation mode, the driving time (aging time) of each of the developing devices 4a to 4d, and the number of cycle repetitions can be appropriately set according to the initial filling toner amount and the specifications of the developing device. However, as the number of rotations of the developing unit 4 increases, the toner dispersion effect increases, but noise associated with the unit rotation becomes a problem. Therefore, the number of rotations of the developing unit 4 is preferably 2 times or less.

  In addition, the longer the aging time, the higher the toner dispersion effect, but the toner deterioration due to mechanical stress becomes remarkable. By setting the aging time to 5 seconds or more and 10 seconds or less for each developing device, a sufficient dispersion effect can be obtained while suppressing toner deterioration.

  The greater the number of cycle repetitions, the higher the toner dispersion effect. However, the toner installation mode takes a long time and it takes time to install the toner. If the number of rotations of the developing unit 4 is 2 times or less and the aging time of each of the developing devices 4a to 4d is 5 seconds or more and 10 seconds or less, the number of repetitions of 4 times or less is sufficient to obtain a sufficient toner dispersion effect. is there.

  Next, the control path of the image forming apparatus of the present invention will be described. FIG. 3 is a block diagram showing an example of a control path used in the image forming apparatus of the present invention. Note that various control of each part of the apparatus is performed when the image forming apparatus 100 is used, so that the control path of the entire image forming apparatus 100 becomes complicated. Therefore, here, a portion of the control path that is necessary for the implementation of the present invention will be mainly described.

  The control unit 90 includes a central processing unit (CPU) 91 as a central processing unit, a read only memory (ROM) 92 that is a read-only storage unit, a random access memory (RAM) 93 that is a read / write storage unit, A plurality of (two in this case) that transmit a control signal to each device in the temporary storage unit 94, the counter 95, and the image forming apparatus 100 for storing image data and the like, and receive an input signal from the operation unit 50. The I / F (interface) 96 is provided. Further, the control unit 90 can be arranged at an arbitrary location inside the apparatus main body.

  The ROM 92 stores a control program for the image forming apparatus 100, data necessary for control, and the like that are not changed during use of the image forming apparatus 100. The RAM 93 stores necessary data generated during the control of the image forming apparatus 100, data temporarily required for controlling the image forming apparatus 100, and the like. The ROM 92 (or RAM 93) also stores the number of rotations of the developing unit 4 per cycle of the toner installation mode, the driving time (aging time) of each of the developing devices 4a to 4d, and the number of repetitions.

  The counter 95 is used for counting the number of printed sheets, and counting the number of rotations of the developing unit 4 and the number of repetitions of the toner installation mode. Note that the number of times may be stored in the RAM 93, for example, without providing the counter 95 separately.

  In addition, the control unit 90 transmits a control signal from the CPU 91 to the respective units and apparatuses in the image forming apparatus 100 through the I / F 96. In addition, a signal indicating the state and an input signal are transmitted from each part or device to the CPU 91 through the I / F 96. Examples of each part and device controlled by the control unit 90 include the photosensitive drum 1, the exposure unit 3, the developing unit 4 (developing devices 4a to 4d), the paper feeding mechanism 9, the fixing device 13, and the operation unit 50. It is done.

  The operation unit 50 is provided with a liquid crystal display unit 51, LEDs 52 indicating various states, and a numeric keypad 53, and the user operates the operation unit 50 to input instructions, thereby making various settings of the image forming apparatus 100. And execute various functions such as image formation. The liquid crystal display unit 51 displays the state of the image forming apparatus 100, displays the image forming status and the number of copies, and can be used as a touch panel to perform various settings such as functions such as double-sided printing and black-and-white reversal, magnification setting, and density setting. It has become. The numeric keypad 53 is used for setting the number of copies to be printed and for inputting the other party's FAX number when the image forming apparatus 100 also has a FAX function.

  In addition, the operation unit 50 includes a start button for instructing the user to start image formation, a stop / clear button used when the image formation is stopped, and various settings of the image forming apparatus 100 in a default state. A reset button or the like is provided for use.

  Next, the operation of the image forming apparatus of this embodiment will be described. FIG. 4 is a flowchart showing the operation at the time of initial toner installation of the image forming apparatus of the present invention. With reference to FIGS. 1 and 3, the procedure for executing the toner installation mode will be described in accordance with the steps in FIG.

  First, in an initial state of the image forming apparatus (a state where the power is turned on for the first time after the apparatus is shipped), an initial installation start signal for prompting toner installation to each of the developing devices 4a to 4d is automatically generated. When the CPU 91 detects an initial installation start signal (step 1), the CPU 91 calculates the rotation number n1 of the developing unit 4 stored in the ROM 92 (or RAM 93), the aging time of the developing devices 4a to 4d, and the toner installation mode repetition number n2. At the same time as reading, a control signal is transmitted to the developing unit 4, and the rotating operation of the developing unit 4 is started (step S2). At the same time, the counter 95 starts counting the number of rotations of the developing unit 4.

  Next, it is determined whether or not the number of rotations of the developing unit 4 has reached a predetermined number (here, n1) (step S3). If the number of rotations is not n1, the rotation is continued. When the number of rotations of the developing unit 4 reaches n1, the developing unit 4 is temporarily stopped and one of the developing devices 4a to 4d (for example, the developing device 4a) is moved to the home position (step S4). Then, the developing device is aged for a predetermined time (here, t seconds) at the home position. The other developing devices (4b to 4d) are sequentially moved to the home position and similarly aged for a predetermined time.

  Thereafter, it is determined whether or not aging has been completed for all the developing devices 4a to 4d (step S6). If there is a developing device that has not finished aging, the remaining developing devices are moved to the home position and aged. Repeat (steps S4, 5). When the aging of all the developing devices 4a to 4d has been completed in step S6, the number of repetitions of the toner installation mode in which the rotation operation of the developing unit 4 and the aging of each developing device 4a to 4d are one cycle is a predetermined number ( Here, it is determined whether or not n2 times has been reached (step S7). If the number of repetitions has not reached n2, the process returns to step S2, and the rotation operation of the developing unit 4 and the aging of the developing devices 4a to 4d are repeated (steps S2 to S5).

  When the number of repetitions reaches n2, the toner installation mode is terminated, the developing device 4a is moved to the home position, and then the supply pipe 5a is extended from the toner cartridge 5 to initially install cyan toner on the developing device 4a. . Similarly, the developing devices 4b to 4d sequentially move to the home position and initially install magenta, yellow, and black toners, respectively (step S8).

  By performing the above control, the initial filling toner filled in the developing devices 4a to 4d before the start of the initial installation is sufficiently dispersed, and the toner surface in the device is made uniform. Accordingly, erroneous detection of the toner amount detection sensor 31 during initial installation is prevented, and an accurate amount of toner is installed in each of the developing devices 4a to 4d.

  In addition, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the spirit of the present invention. For example, in the above-described embodiment, the case where the one-component developer composed only of the toner component is used has been described. However, the present invention can be similarly applied to the case where the two-component developer composed of the toner and the carrier is used. The present invention is not limited to the color printer as shown in FIG. 1, but can be applied to other image forming apparatuses using a rotary developing system such as a color copying machine and a facsimile. Hereinafter, the effects of the present invention will be described in more detail with reference to examples.

  Before the initial installation of toner in the image forming apparatus of the present invention shown in FIG. 1, the effect of executing a predetermined toner installation mode was investigated. As the toner installation mode, the rotation operation of the developing unit 4 and the aging of each of the developing devices 4a to 4d are defined as one cycle, and the present invention is set to 1 to 5 of the present invention. On the other hand, the case where only the aging of the developing devices 4a to 4d is performed is referred to as Comparative Example 1, and the case where only the rotation operation of the developing unit 4 is performed is referred to as Comparative Example 2. Table 1 shows the number of rotations of the developing unit, the driving time of each of the developing devices 4a to 4d, and the number of repetitions in the present inventions 1 to 5 and Comparative Examples 1 and 2.

  The evaluation of the toner installation mode is comprehensively evaluated with respect to four items of total operation time, toner dispersion effect (leveling effect) after operation, noise during operation, and toner deterioration, and three stages of ○, Δ, and ×. Judged by. Regarding the toner dispersion effect, the height of the toner surface in each developing device after the end of the operation was measured and compared with a target value of 20 mm that does not affect the detection of the toner amount. Toner deterioration was evaluated by the occurrence of background fog when the first toner installation was performed after the operation was completed and a test image was printed immediately thereafter. The results are shown in Table 2. FIG. 5 shows the relationship between the aging time and the toner surface height when only the developing device is aged, and FIG. 6 shows the relationship between the number of rotations and the toner surface height when only the developing unit is rotated. .

  As apparent from Table 2, in the present inventions 1 to 5 in which the toner installation mode in which the rotation of the developing unit and the aging of the developing device are combined is executed, the toner surface height is in the range of 18 mm to 25 mm, both of which are target values. In the present invention 2, 3, and 5, it was below the target value. Further, there was no occurrence of background fog immediately after the initial installation, and no toner deterioration was observed. Furthermore, noise during operation does not feel uncomfortable, and the total operation time does not feel long for the user.

  On the other hand, in Comparative Example 1 in which only the aging of the developing device was performed, the toner surface height was 20 mm, which was the target value. However, the toner deteriorated due to mechanical stress due to aging, and background fogging occurred immediately after the initial installation. Here, as shown in FIG. 5, it can be understood that the aging time of each developing device needs to be 20 seconds or more in order to set the height of the toner surface of the developing device to a target value of 20 mm or less. Accordingly, it has been confirmed that when only the aging of the developing device is performed, it is impossible to achieve both the toner dispersion effect and the suppression of toner deterioration.

  Further, in Comparative Example 2 in which only the development unit was rotated, the toner surface height was 17.5 mm, which was below the target value, but noise that was uncomfortable for the user was generated. Here, as shown in FIG. 6, it is understood that the developing unit needs to be rotated about 30 times in order to set the toner surface height of the developing device to 20 mm or less which is the target value. Accordingly, it has been confirmed that when only the developing unit is rotated, the toner dispersion effect and the noise reduction of the apparatus cannot be achieved at the same time.

  The total aging time of each developing device is 5 (sec / time) × 4 (times) = 20 sec in the present invention 5, which is the same as that in Comparative Example 1 (20 sec × 1 time), and 7 in the present invention 2. (Sec / times) × 3 (times) = 21 sec. In the third aspect of the invention, 10 (sec / times) × 3 (times) = 30 sec, which exceeds Comparative Example 1. The total aging time is one of the factors affecting the toner deterioration, but the developing device used in the present invention uses the rotation of the rotary developing unit to circulate the toner in the developing device. The toner is not configured to circulate efficiently when the device is driven. This is because, in a normal printing operation, the developing device is driven only during the time for printing one sheet of paper (for example, A4 size), so that the toner circulation performance is hardly required.

  However, when the developing device is continuously aged as in Comparative Example 1, since the toner hardly circulates, mechanical stress concentrates on a part of the toner, and the toner deterioration rate becomes faster than that during normal printing. On the other hand, when the rotating operation of the developing unit and the aging of the developing device are alternately performed as in the present invention, the toner circulates during the rotation of the developing unit. Therefore, even if the total aging time is longer than that in Comparative Example 1, It is considered that no deterioration occurs.

  The present invention relates to a rotary developing unit in which a plurality of developing devices containing a developer are arranged along the circumferential direction of a rotating body, and toner supply for additionally supplying toner to the developing devices in the developing unit. An image forming apparatus that develops an electrostatic latent image on the image carrier by moving one of the development devices to a position facing the image carrier by rotation of the development unit. In this case, a predetermined amount of toner is initially filled in advance, and before the first toner replenishment operation by the toner replenishing means, the rotation operation of the developing unit and the driving of each developing device following the rotation operation are set as one cycle. The toner installation mode is executed at least once.

  As a result, the initial filling toner is sufficiently dispersed to prevent the initial toner replenishment failure, and the image forming apparatus capable of suppressing the image failure due to the deterioration of the initial filling toner and the noise accompanying the dispersion with a simple configuration. Can be provided.

  Further, since the rotation speed of the developing unit in the toner installation mode is higher than the rotation speed at the time of image formation, the toner in the developing device can be stirred more effectively in a short time, and the execution time of the toner installation mode is also increased. Can be shortened.

  Further, since the number of rotations of the developing unit in one cycle of the toner installation mode is set to 2 times or less, the driving time of each developing device is set to 5 seconds to 10 seconds, and the cycle repetition number is set to 4 times or less, the toner installation mode The execution condition becomes a necessary and sufficient condition for the dispersion of the initial filling toner, and the time required for the initial toner installation can be minimized.

These are side cross-sectional views of the color image forming apparatus of the present invention provided with a rotary type developing unit. These are side surface sectional views of the developing device mounted in the developing unit. FIG. 3 is a block diagram showing a control path of the image forming apparatus of the present invention. These are flowcharts showing the operation of the image forming apparatus of the present invention during initial toner installation. These are graphs showing the relationship between the aging time and the toner surface height when only the aging of the developing device is performed. These are graphs showing the relationship between the number of rotations and the toner surface height when only the rotation operation of the developing unit is performed.

Explanation of symbols

1 Photosensitive drum (image carrier)
4 Developing unit 4a to 4d Developing device 5 Toner cartridge (toner supply means)
5a Supply pipe (toner supply means)
DESCRIPTION OF SYMBOLS 20 Developing container 25 Developing roller 26 Toner supply roller 27 Control member 30 Seal member 90 Control part 100 Image forming apparatus

Claims (3)

A rotary developing unit in which a plurality of developing devices containing a developer are disposed along the circumferential direction of the rotating body;
Toner replenishing means for additionally replenishing toner to the developing device in the developing unit,
In the image forming apparatus for developing the electrostatic latent image on the image carrier by moving any of the developing devices to a position facing the image carrier by the rotation of the developing unit,
Each developing device is initially filled with a predetermined amount of toner in advance, and before the first toner replenishing operation by the toner replenishing means, the developing unit is rotated, and each developing device following the rotating operation. An image forming apparatus that executes a toner installation mode in which at least one drive is performed in one cycle.   The image forming apparatus according to claim 1, wherein a rotation speed of the developing unit in the toner installation mode is higher than a rotation speed at the time of image formation.   The number of rotations of the developing unit in one cycle of the toner installation mode is 2 or less, the driving time of each developing device is 5 seconds or more and 10 seconds or less, and the number of repetitions of the cycle is 4 or less. The image forming apparatus according to claim 1.

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