JP2007249109A - Method for adjusting developing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for adjusting a developing device with which stable image quality is maintained by appropriately adjusting the amount of toner conveyed to a developing roll. <P>SOLUTION: Provided is the method for adjusting the developing device equipped with a magnetic roll 143 holding two-component developer 145 with which a developing tank 142 is filled and which is composed of carrier and toner in a brush state, and the developing roll 144 holding the toner conveyed from the magnetic roll 143 and developing an electrostatic latent image formed on an image carrier 110, and equipped with a bias voltage adjusting step for adjusting the conveying amount of toner from the magnetic roll 143 to the developing roll 144 by adjusting bias voltage Vdc3 and bias voltage Vdc4 applied to the magnetic roll 143 and the developing roll 144 respectively. In such a case, the method includes a revolving speed adjusting step for adjusting the conveying amount of toner by adjusting the difference of the rotating speed between the magnetic roll 143 and the developing roll 144. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a magnetic roll for holding a two-component developer composed of a carrier and toner filled in a developing tank in a brush shape, and an electrostatic formed on an image carrier holding the toner conveyed from the magnetic roll. A bias voltage adjusting step of adjusting a toner conveyance amount from the magnetic roll to the developing roll by adjusting a bias voltage applied to each of the magnetic roll and the developing roll, the developing roll including a developing roll for developing a latent image; The present invention relates to a method of adjusting a developing device provided.

  As a developing device incorporated in an electrophotographic image forming apparatus, Patent Document 1 discloses a stable image in which the toner layer thickness on the developing roller is always stabilized over a long period of time without making the developing device complicated, and there is no density change. In order to maintain the above, a solid pattern using a toner layer formed on the second turn after starting to apply the developing bias to the developing roll on the image carrier and the next rotation was formed. The toner layer thickness detection pattern arranged with the halftone pattern using the toner layer is visualized, and the toner layer thickness detection pattern on the image carrier or the toner layer thickness detection pattern transferred to the transfer body A developing method that detects the toner density with a density sensor and controls the difference voltage of the bias voltage between the magnetic roll and the developing roll based on the detected toner density, that is, the transport bias voltage. There has been proposed.

JP 2005-55841 A

  However, the above-described prior art is adjusted under the condition that the charge amount of the toner filled in the developing tank is controlled within an ideal charge amount range, and the toner charge amount varies. There was a problem that it could not be adjusted properly.

  For example, the density of the halftone pattern is detected, and the transport bias voltage is set based on the detection result. However, depending on the charge amount of the toner, the transport bias value to be adjusted becomes too high, and the developing roll and the magnetic roll Leaks occurred between the images, causing image defects such as black spots. In addition, the distance between the developing roll and the magnetic roll is narrowed, and there is a possibility that toner conveyance trouble occurs and toner scattering or agent leakage occurs. Conversely, if the transport bias voltage becomes too low, the toner supply amount cannot catch up with the toner consumption amount on the developing roll, and there is a possibility that a development ghost in which the previous development history affects the next development may occur.

  SUMMARY OF THE INVENTION In view of the above-described conventional drawbacks, the present invention is to provide a developing device adjustment method capable of maintaining a stable image quality by appropriately adjusting the amount of toner conveyed to a developing roll.

  In order to achieve the above-mentioned object, the first characteristic configuration of the developing device adjustment method according to the present invention comprises a carrier and a toner filled in a developing tank, as described in claim 1 of the claims. A magnetic roll that holds the two-component developer in a brush shape; and a developing roll that holds the toner conveyed from the magnetic roll and develops the electrostatic latent image formed on the image carrier. A developing apparatus adjustment method comprising a bias voltage adjustment step of adjusting a transfer amount of toner from the magnetic roll to the development roll by adjusting a bias voltage applied to each of the development rolls, A rotation speed adjustment step of adjusting the toner conveyance amount by adjusting a difference in rotation speed of the developing roll is provided.

  When the charge amount of the toner contained in the two-component developer is not appropriate, for example, the amount of toner transported from the magnetic roll to the developing roll is sufficiently adjusted by adjusting the bias voltage applied to each of the magnetic roll and the developing roll. Although it may not be able to be adjusted, according to the configuration described above, the toner conveyance amount can be reliably adjusted by adjusting the difference in rotational speed between the magnetic roll and the developing roll.

  According to the second characteristic configuration, as described in the second aspect, in addition to the first characteristic configuration described above, when the toner conveyance amount cannot be adjusted to a predetermined conveyance amount by the bias voltage adjustment step, the rotation speed is set. The adjustment step is performed.

  It is not desirable to apply a bias voltage that is too high or too low to maintain image quality by preventing the occurrence of toner scattering, black or white spots, development ghosts, and economics such as energy saving and durability of materials. Although it is desirable to apply the bias voltage within a preferable output range obtained through the above-described case, the toner transport amount may not be adjusted to a predetermined transport amount within the preferable output range. According to the above-described configuration, it is possible to adjust the bias voltage within the preferable output range to set the toner conveyance amount to a predetermined conveyance amount.

  In the third feature configuration, in addition to the first or second feature configuration described above, the bias voltage adjustment step applies at least a predetermined low-voltage bias voltage to the developing roll. The bias voltage applied to the magnetic roll is adjusted so that the density of the solid pattern formed on the image carrier in the state or the density of the solid pattern after transfer to the transfer body becomes a predetermined density.

  In a state where a predetermined low-voltage bias voltage is applied to the developing roll, that is, in a state where development efficiency is low, the bias voltage applied to the magnetic roll is adjusted so that the solid pattern has a predetermined density, that is, the developing roll In order to adjust the transport bias voltage, which is the difference voltage between the bias voltages applied to both of the magnetic rolls, the condition that the excessive toner is transported to the developing roll is eliminated, and the toner formed on the developing roll is removed. The layer thickness can be adjusted appropriately.

  As described above, according to the present invention, it is possible to provide a method of adjusting a developing device that can appropriately adjust the amount of toner conveyed to the developing roll and maintain stable image quality.

  The developing device adjustment method according to the present invention will be described below. A printer as an example of an electrophotographic image forming apparatus including a developing device according to the present invention forms a toner image of each color component of MCYK based on a print job input from an external device as shown in FIG. An image forming unit 1, a paper feeding unit 2 including a paper tray and a conveyance roller for supplying, conveying, and discharging a sheet as a recording medium, an endless transfer member 31 supported by three rollers 30, A transfer unit 3 including a plurality of transfer rollers 32 and 33 arranged in contact with the transfer body 31; a fixing unit 4 for fixing a recording medium to which a toner image is transferred; and the external device. An interface unit 5 that performs data transmission and reception and a system control unit 6 that includes a microcomputer that performs overall control of the printer are included.

  The image forming unit 1 includes four photoconductor units 100 corresponding to M (magenta), C (cyan), Y (yellow), and K (black) colors arranged along the circumferential direction of the transfer body 31. A toner density sensor 11 for detecting the density of each color based on the amount of reflected light from the toner pattern of each color carried on the transfer body 31 so that the density of the toner image to be formed is maintained at a predetermined density; As shown in FIG. 1, each photoconductor unit 100 includes an image carrier 110, a charging charger 120, and exposure along the circumferential direction of the image carrier 110. A head 130, a developing device 140, a cleaner 150, a charge removal lamp 160, and the like are arranged.

  The image carrier 110 includes a photosensitive drum having a photosensitive member in which an amorphous silicon layer, which is a positively chargeable photoconductor, is deposited on the surface of an aluminum cylinder, and is positively charged by the charging charger 120. By the exposure from 130, the charge in the exposed portion is grounded through the cylinder.

  The toner density sensor 11 is disposed on the downstream side of the photoreceptor unit 100 disposed along the circumferential direction of the transfer body 31. The toner density sensor 11 will be described in detail. The toner density sensor 11 projects a single polarized light at a predetermined inclination angle with respect to the normal direction of the transfer body 31 as shown in FIG. The light unit 13 is disposed on the opposite side to the light projecting unit 13 with respect to the normal direction, and the reflected light from the transfer body 31 is the same as the first polarized light and the light projecting light. And a first and second light receiving parts 15 for receiving the first and second polarized lights, and the first and second light receiving parts 15 for receiving the first and second polarized lights. The toner density is detected from the light amount difference of the second polarized light.

  As shown in FIG. 1, the developing device 140 provided in each of the photoreceptor units 100 of M (magenta), C (cyan), Y (yellow), and K (black) colors corresponds to the corresponding colors. A toner cartridge 141 filled with the toner, a developer tank 142 that stirs the toner and carrier supplied from the toner cartridge 141, and a two-component developer 145 composed of the carrier and toner filled in the developer tank 142. A magnetic roll 143 for holding the magnetic brush 143l, and a developing roll for developing the electrostatic latent image formed on the image carrier 110 by holding the toner conveyed from the magnetic roll 143 as a toner thin layer 144l. 144.

  The magnetic roll 143 is composed of a rotating sleeve including a fixed magnet roller in which N poles and S poles are alternately magnetized, and a DC bias voltage (hereinafter referred to as “bias voltage”) Vdc3 is applied to the rotating shaft thereof. A high voltage circuit 143v is connected, and the rotating shaft is connected to a drive mechanism 146m composed of a motor and a speed reduction mechanism so that the magnetic roll 143 rotates in one direction at a predetermined rotation speed. The rotational speed is configured to be controllable.

  The developing roll 144 is made of uniformly charged aluminum, and a high voltage circuit 144v for applying an AC bias voltage Vac4 and a bias voltage Vdc4 is connected to the rotation axis thereof. Further, the developing roll 144 is rotated at a predetermined rotation speed. The rotation shaft is connected to a drive mechanism 146s composed of a motor and a speed reduction mechanism so as to rotate in one direction, and the rotation speed thereof can be controlled by the control unit 12.

  The control unit 12 adjusts a transport bias voltage ΔVc, which is a difference voltage between bias voltages applied to both the magnetic roll 143 and the developing roll 144, so that the toner from the magnetic roll 143 to the developing roll 144 is adjusted. Adjust the transport amount.

  The control unit 12 executes calibration control at a preset period, that is, when the cumulative operation time of the developing device 140 reaches a predetermined time, or when the cumulative number of printed sheets reaches a predetermined number of printed sheets. Is configured to do.

  That is, the density of the solid pattern formed on the image carrier 110 or the solid pattern after transfer to the transfer body 31 with a predetermined low voltage bias voltage Vdc4 (L) applied to at least the developing roll 144 is a predetermined density. A bias voltage adjustment step of adjusting the bias voltage Vdc3 applied to the magnetic roll 143 is performed so that

Here, when the toner conveyance amount cannot be adjusted to a predetermined conveyance amount by the bias voltage adjusting step, the toner conveyance amount is adjusted by adjusting the difference in rotational speed between the magnetic roll 144 and the developing roll 143. By executing the rotation speed adjustment step and then executing the bias voltage adjustment step again, the toner conveyance amount is reliably adjusted to a predetermined conveyance amount.

  Further, after the bias voltage adjustment step, the density of a predetermined halftone pattern formed on the image carrier 110 or a predetermined halftone pattern after transfer to the transfer body 31 becomes a predetermined density. A second bias voltage adjustment step is performed in which both bias voltages are adjusted while maintaining the transport bias voltage ΔVc, which is a difference voltage between bias voltages applied to the magnetic roll 143 and the developing roll 144, constant.

  Note that the bias voltage adjustment step is not limited to the adjustment method described above, and in order to detect the toner layer thickness on the developing roller 144 on the image carrier 110 according to Patent Document 1, the development is performed. A toner layer in which a solid pattern using a toner layer formed on the second turn after applying the developing bias of the roller 144 and a halftone pattern using a toner layer formed during the next rotation are arranged The thickness detection pattern is visualized, and the toner layer thickness on the transfer body 31 to which the toner layer thickness detection pattern on the image carrier 110 or the toner layer thickness detection pattern on the image carrier 110 is transferred. The toner density in the detection pattern is detected by the toner density sensor 11, and the toner layer on the developing roller 144 is controlled to a predetermined layer thickness by the detected toner density. Such adjustment method of may be one using other adjustment methods.

  This will be described in detail below. When the cumulative operating time of the developing device 140 reaches a predetermined time or when the cumulative number of printed sheets reaches a predetermined number of printed sheets, the control unit 12 sets a predetermined number of rotations Ns (for each color photoconductor unit 100). The bias voltage Vdc4 is fixed to a predetermined low-voltage bias voltage Vdc4 (L) close to the minimum output voltage without changing the AC bias voltage Vac4 applied to the developing roll 144 that rotates at R), and is rotated at a predetermined speed. Several patterns of the bias voltage Vdc3 are applied to the magnetic roll 143 rotating at several Nm (R), and a toner image that becomes a solid pattern in each pattern is formed on the image carrier 110 and carried on the transfer member 31. .

  In order to monitor the amount of toner transported from the magnetic roll 143 to the developing roll 144, the toner density sensor 11 detects the toner density value of each toner image, and the detected toner density value is the control unit 12. The bias voltage Vdc3 (O) that is a predetermined toner density value at the time of solid pattern formation stored in a storage unit (not shown) is obtained, and the toner transport amount is adjusted.

  When the bias voltage Vdc3 (O) at which the density of the solid pattern formed on the image carrier 110 or the solid pattern after transfer to the transfer body 31 is a predetermined density is not required, the magnetic roll 143 or the developing roll The rotation number that adjusts the rotation speed difference between the magnetic roll 143 and the developing roll 144 by changing the rotation number of 144 or by changing both the rotation number of the magnetic roll 143 and the rotation number of the developing roll 144. An adjustment step is executed, and then the bias voltage adjustment step is executed again to adjust the toner conveyance amount. In this embodiment, only the rotational speed of the magnetic roll 143 is changed.

  More specifically, first, in the execution of the bias voltage adjustment step, the bias voltage Vdc4 is fixed to a predetermined bias voltage Vdc4 (L) close to the minimum output voltage, and the magnetic roll 143 is provided with first to fourth biases. By applying a pattern bias voltage Vdc3, four solid pattern toner images are formed on the image carrier 110, and the toner image is carried on the transfer member 31 as shown in FIG. The density sensor 11 detects the toner density value of the toner image of each of the four patterns.

  As shown in FIG. 5, from the characteristic curve obtained from the transport bias voltage ΔVc, which is the difference between the bias voltage Vdc3 and the bias voltage Vdc4 (L), and the detected toner density value, the control unit 12 stores the memory (not shown). An optimum transport bias voltage ΔVc (O) that is a predetermined toner density value at the time of solid pattern formation stored in the section is obtained, and from the optimum transport bias voltage ΔVc (O) and the bias voltage Vdc4 (L), The bias voltage Vdc3 (O) is obtained, and each of the bias voltages is applied to adjust the toner conveyance amount to a predetermined conveyance amount.

  Here, the transport characteristics of the toner transported from the magnetic roll 143 to the developing roll 144 change due to an increase or decrease in the toner charge amount of the two-component developer 145 in the developing tank 142, a carrier coat peeling, or the like. When the optimum transport bias voltage ΔVc (O) cannot be obtained without outputting the bias voltage Vdc3 that deviates from the output range, the rotational speed Nm (R) of the magnetic roll 143 is set to a preset value Nm. The conveyance characteristic is changed by executing the rotation speed adjustment step to be changed to (O), and then the bias voltage adjustment step is performed again to obtain the optimum conveyance bias voltage ΔVc (O). Adjust the toner transport amount.

  The rotation speed adjustment step will be described in detail. As shown in FIG. 6, since the toner transport characteristics are improved when the toner charge amount of the two-component developer 145 is lowered, the minimum transport bias voltage ΔVc (min) is used. Excess toner is transported. Conversely, when the toner charge amount is increased, the toner transport characteristics are deteriorated, so that sufficient toner is not transported even at the highest transport bias voltage ΔVc (max). Therefore, the controller 12 rotates the magnetic roll 144 based on the characteristic curve obtained when the bias voltage adjustment step is executed while the rotation speed Ns (R) of the developing roll 144 remains constant. Nm (R) is obtained through an experiment or the like, changed to a preset value Nm (O), and the rotational speed difference between the magnetic roll 143 and the developing roll 144 is low in the former case and high in the latter case. By changing the toner transport characteristics, the bias voltage adjustment step is executed again, the optimum transport bias voltage ΔVc (O) is obtained, and the density of the solid pattern transferred to the transfer body 31 is determined. Adjust to a predetermined density.

  Further, the optimum transport bias voltage ΔVc (O) is set so that the density of a predetermined halftone pattern formed on the image carrier 110 or a predetermined halftone pattern after transfer to the transfer body 31 becomes a predetermined density. The second bias voltage adjustment step for adjusting the bias voltages Vdc3 and Vdc4 is executed while maintaining the above, and the calibration control is terminated.

  Hereinafter, another embodiment will be described. In the configuration described above, a photosensitive drum having a photosensitive body in which an amorphous silicon layer, which is a positively chargeable photoconductor, is deposited on the surface of an aluminum cylinder is used as the image carrier 110. However, the photosensitive body is organic. OPC drums that are photoconductors or other types of photoconductive semiconductor drums in which the photoconductor is selenium or the like may be adopted. In this case, the photoconductor is used according to the charging characteristics of the photoconductor. The two-component developer to be used may be changed as appropriate.

  In the above-described embodiment, with respect to the adjustment of the rotational speed difference between the magnetic roll 143 and the developing roll 144, the control unit 12 keeps the rotation speed Nm (R) of the developing roll 143 constant, The rotational speed Nm (R) is changed to a preset value Nm (O) through an experiment or the like. However, the present invention is not limited to this, and only the rotational speed of the developing roll 144 is changed, or the magnetic roll A configuration may be employed in which both the rotational speed of 143 and the rotational speed of the developing roll 144 are changed. However, when the rotation speed of the developing roll 144 is changed, at least when the rotation speed is lowered, the rotation speed of the image carrier 110 or the like needs to be changed accordingly. This is because if the rotation speed of the developing roll 144 changes, the toner conveyance characteristics to the image carrier 110 change, and in particular, the influence is great when the rotation speed of the developing roll 144 is lowered. is there.

  In the above-described embodiment, four patterns of toner images are formed in the detection of the toner density value. However, the present invention is not limited to this, and an optimum pattern of toner images is selected according to various conditions such as device characteristics, use conditions, and costs. A configuration may be adopted in which the toner density values of the toner images of the respective patterns are detected, and the bias voltages Vdc3 and Vdc4 applied to the magnetic roll 143 and the developing roll 144 may be adjusted.

  In the above-described configuration, the rotation speed adjustment step is performed based on the characteristic curve obtained when the bias voltage adjustment step is executed while the rotation speed Ns (R) of the developing roll 144 remains constant. The rotational speed Nm (R) is obtained through an experiment or the like, changed to a preset value Nm (O), and the rotational speed difference between the magnetic roll 143 and the developing roll 144 is low in the former case, and in the latter case. However, the bias voltage Vdc3 is adjusted so that the transport bias voltage ΔVc becomes a predetermined value, and at the transport bias voltage ΔVc, the predetermined toner is changed. The rotational speed difference may be linearly changed so as to obtain the transport amount in this case. In this case, after the rotation speed adjustment step is performed, the bias is again applied. There is no need to perform a voltage adjustment step.

  In the above-described configuration, the rotation speed adjustment step is performed based on the characteristic curve obtained when the bias voltage adjustment step is executed while the rotation speed Ns (R) of the developing roll 144 remains constant. The rotational speed Nm (R) is obtained through an experiment or the like, changed to a preset value Nm (O), and the rotational speed difference between the magnetic roll 143 and the developing roll 144 is low in the former case, and in the latter case. However, the bias voltage Vdc3 is adjusted so that a predetermined toner conveyance amount can be obtained after the rotation speed difference is changed to a predetermined value. In this case, it is not necessary to perform the bias voltage adjustment step again after the rotation speed adjustment step.

  The above-described embodiments are merely examples of the present invention, and the scope of the present invention is not limited by the description, and the specific configuration of each part is appropriately changed within the scope of the effects of the present invention. It goes without saying that it can be done.

Explanatory drawing of developing device Explanatory drawing of the printer in this embodiment Explanatory drawing of the toner density sensor which detects the toner density on the transfer body in this embodiment Explanatory drawing of the toner image formed on the transfer body The graph which shows the relationship between a conveyance bias voltage and the toner density value (toner conveyance amount to a developing roll) of the solid pattern toner image on a transfer body Graph used to explain the transport characteristics of the toner transport amount to the developing roll

Explanation of symbols

12: Control unit 100: Photosensitive unit 140: Developing device 141: Toner cartridge 142: Developing tank 143: Magnetic roll 143l: Magnetic brush 143v: High voltage circuit (for magnetic roll)
144: Developing roll 144l: Toner thin layer 144v: High voltage circuit (for developing roll)
145: Two-component developer (toner and carrier)
146m: Drive mechanism (for magnetic roll)
146s: Drive mechanism (for developing roll)

Claims (3)

A magnetic roll that holds a two-component developer consisting of a carrier and toner filled in a developing tank in a brush shape, and an electrostatic latent image formed on an image carrier by holding the toner conveyed from the magnetic roll. And a developing device including a bias voltage adjusting step for adjusting a toner conveyance amount from the magnetic roll to the developing roll by adjusting a bias voltage applied to each of the magnetic roll and the developing roll. Adjustment method,
A developing device adjustment method comprising a rotation speed adjustment step of adjusting a toner conveyance amount by adjusting a rotational speed difference between the magnetic roll and the developing roll.   The developing device adjustment method according to claim 1, wherein the rotation speed adjustment step is executed when the toner conveyance amount cannot be adjusted to a predetermined conveyance amount by the bias voltage adjustment step.   In the bias voltage adjustment step, the density of the solid pattern formed on the image carrier or the solid pattern after transfer to the transfer body is a predetermined density at least in a state where a predetermined low-voltage bias voltage is applied to the developing roll. The method for adjusting a developing device according to claim 1, wherein a bias voltage applied to the magnetic roll is adjusted.

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