Image forming device

Abstract

To stabilize the printing density of an image forming apparatus.SOLUTION: An image forming apparatus comprises a drum cartridge, a toner cartridge; and a control unit. The drum cartridge has a photoreceptor drum and a drum memory that stores the cumulative number of drum rotations of the photoreceptor drum. The toner cartridge has a developing roller and a toner memory that stores the cumulative dot counts. When image formation is performed on the drum cartridge with the use of a first toner cartridge, the control unit can execute processing of determining an initial developing bias VG1 applied to the developing roller when image formation is performed with the first toner cartridge based on the cumulative number of drum rotations, and after the initial developing bias VG1 is determined, when image formation is performed with the use of a second toner cartridge, can execute processing of determining an initial developing bias VG2 different from the initial developing bias VG1 based on the cumulative number of drum rotations.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present disclosure relates to an image forming apparatus into which a drum cartridge and a toner cartridge can be attached. [Background technology]

[0002] Conventionally, there is known an image forming apparatus into which a drum cartridge and a toner cartridge can be attached (see Patent Document 1). In this image forming apparatus, the toner cartridge is assembled into the drum cartridge, and then the image forming apparatus is attached to the main body of the apparatus. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2009-265401 A Summary of the Invention [Problem to be solved by the invention]

[0004] Generally, the lifespan of a drum cartridge is longer than that of a toner cartridge. For this reason, multiple toner cartridges may be used in conjunction with one drum cartridge. However, if the first toner cartridge and the second or subsequent toner cartridges are used under the same conditions, the amount of toner supplied changes, resulting in unstable print density.

[0005] Therefore, an object of the present disclosure is to stabilize the print density of an image forming apparatus. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems, the image forming apparatus includes a main body, a drum cartridge, a toner cartridge, and a control device. The drum cartridge has a photosensitive drum and a drum memory that stores the cumulative number of drum rotations of the photosensitive drum, and is detachable from the main body. The toner cartridge has a developing roller and a toner memory that stores the cumulative dot count. When a first toner cartridge is used for image formation with respect to the drum cartridge, the control device determines an initial developing bias V to be applied to the developing roller when image formation is performed with the first toner cartridge based on the cumulative number of drum rotations. G1 and the process of determining the initial developing bias V G1 After the first toner cartridge is determined, when a second toner cartridge different from the first toner cartridge is used in the drum cartridge to form an image, the initial developing bias V is determined based on the cumulative number of drum rotations. G1 Different initial development bias V G2 and determining a process for determining whether the

[0007] According to this configuration, the initial developing bias V G1 and initial development bias V G2 By making the toner amount adhered to the photosensitive drum when the second toner cartridge is used different from the toner amount adhered to the photosensitive drum when the first toner cartridge is used, the print density of the image forming device can be stabilized.

[0008] In the above-mentioned configuration, the control device may be configured to change the developing bias applied to the developing roller in response to an increase in the cumulative number of drum rotations and the cumulative dot count.

[0009] According to this, since the developing bias is changed in response to both the deterioration of the photosensitive drum and the deterioration of the toner, the amount of toner adhering to the photosensitive drum can be made constant.

[0010] In the above-mentioned configuration, the control device may be configured to reduce the absolute value of the developing bias as the cumulative dot count increases.

[0011] In the above-mentioned configuration, the absolute value of the developing bias may be reduced as the cumulative number of drum rotations increases.

[0012] In the above-mentioned configuration, |V G2 |>|V G1 It may also be configured as follows: |

[0013] In the above-mentioned configuration, the toner cartridge includes a blade that regulates the thickness of the toner layer supplied to the developing roller, and the control device controls the initial blade bias V to be applied to the blade when the first toner cartridge is used for image formation with respect to the drum cartridge based on the cumulative number of drum rotations. B1 and the process of determining the initial blade bias V B1 After the first toner cartridge is determined, when a second toner cartridge different from the first toner cartridge is used in the drum cartridge to form an image, the initial blade bias V is determined based on the cumulative number of drum rotations. B1 Different initial blade bias V B2 The configuration may be such that the process of determining the above is executable.

[0014] According to this, the initial blade bias V B1 and initial blade bias V B2 By making the toner amount on the developing roller of the second toner cartridge different from the toner amount on the developing roller of the first toner cartridge, the amount of toner supplied from the developing roller to the drum cartridge can be stabilized. As a result, the print density of the image forming device can be stabilized.

[0015] In the above-mentioned configuration, the control device may be configured to change the blade bias applied to the blade in response to an increase in the cumulative number of drum rotations and the cumulative dot count.

[0016] According to this, since the blade bias is changed in response to the deterioration of the photosensitive drum and the toner deterioration, the amount of toner adhering to the photosensitive drum can be made constant.

[0017] In the above-mentioned configuration, the control device may be configured to reduce the absolute value of the blade bias as the cumulative dot count increases.

[0018] In the above-mentioned configuration, the control device may be configured to reduce the absolute value of the blade bias as the cumulative number of drum rotations increases.

[0019] In the above-mentioned configuration, |V B2 |>|V B1 It may also be configured as follows: |

[0020] In the above-mentioned configuration, a supply roller for supplying toner to the developing roller is provided, and the control device determines an initial supply bias V to be applied to the supply roller when an image is formed using the first toner cartridge based on the cumulative number of drum rotations when the first toner cartridge is used for image formation. K1 and the process of determining the initial supply bias V K1 After the first toner cartridge is determined, when a second toner cartridge different from the first toner cartridge is used for the drum cartridge to form an image, the initial supply bias V is determined based on the cumulative number of drum rotations. K1 Different initial supply bias V K2 The configuration may be such that the process of determining the above is executable.

[0021] According to this, the initial supply bias V K1 and the initial supply bias V K2By making the toner amount on the developing roller of the second toner cartridge different from the toner amount on the developing roller of the first toner cartridge, the amount of toner supplied from the developing roller to the drum cartridge can be stabilized. As a result, the print density of the image forming device can be stabilized.

[0022] In the above-mentioned configuration, the control device may be configured to change the supply bias applied to the supply roller in response to an increase in the cumulative number of drum rotations and the cumulative dot count.

[0023] According to this, since the supply bias is changed in response to deterioration of the photosensitive drum and toner deterioration, the amount of toner supplied to the photosensitive drum can be made constant.

[0024] In the above-mentioned configuration, the control device may be configured to increase the absolute value of the supply bias as the cumulative dot count increases.

[0025] In the above-mentioned configuration, the control device may be configured to increase the absolute value of the supply bias as the cumulative number of drum rotations increases.

[0026] In the above-mentioned configuration, |V K2 |>|V K1 It may also be configured as follows: |

[0027] In the above-described configuration, when the first toner cartridge is used for image formation with respect to the drum cartridge, the control device calculates an initial peripheral speed difference ΔV between the developing roller and the photosensitive drum when image formation is performed with the first toner cartridge based on the cumulative number of drum rotations. 1 The process of determining the initial peripheral speed difference ΔV 1 After the first toner cartridge is determined, when a second toner cartridge different from the first toner cartridge is used in the drum cartridge to form an image, the initial peripheral speed difference ΔV is determined based on the cumulative number of drum rotations. 1 The initial peripheral speed difference ΔV2 The configuration may be such that the process of determining the above is executable.

[0028] According to this, the initial peripheral speed difference ΔV 1 and the initial peripheral speed difference ΔV 2 By making the toner amount adhered to the photosensitive drum when the second toner cartridge is used different from the toner amount adhered to the photosensitive drum when the first toner cartridge is used, the print density of the image forming device can be stabilized.

[0029] In the above-mentioned configuration, the control device may be configured to change the difference in peripheral speed between the developing roller and the photosensitive drum in response to an increase in the cumulative number of drum rotations and the cumulative dot count.

[0030] According to this, since the difference in peripheral speed between the developing roller and the photosensitive drum is changed in response to deterioration of the photosensitive drum and toner deterioration, the amount of toner supplied to the photosensitive drum can be made constant.

[0031] In the above-mentioned configuration, the control device may be configured to reduce the peripheral speed difference as the cumulative dot count increases.

[0032] In the above-mentioned configuration, the control device may be configured to reduce the peripheral speed difference as the cumulative number of drum rotations increases.

[0033] In the above configuration, ΔV 2 >ΔV 1 The configuration may be as follows.

[0034] In the above-mentioned configuration, the toner cartridge may be configured to be detachable from the drum cartridge. Effect of the Invention

[0035] According to the image forming apparatus of the present disclosure, it is possible to stabilize the print density. [Brief description of the drawings]

[0036] [Figure 1] 1 is a cross-sectional view of an image forming apparatus according to an embodiment. [Diagram 2] FIG. 4 is a diagram illustrating a connection between an application circuit and a motor. [Diagram 3] 11 is a graph showing the relationship between the cumulative number of drum rotations and the charging bias. [Figure 4] Graph (a) shows the relationship between the cumulative dot count and the development bias reference value, graph (b) shows the relationship between the cumulative dot count and the blade bias reference value, graph (c) shows the relationship between the cumulative dot count and the supply bias reference value, and graph (d) shows the relationship between the cumulative dot count and the peripheral speed difference reference value. [Diagram 5] Graph (a) shows the relationship between the cumulative number of drum rotations and the amount of development bias correction, and graph (b) shows the dot count (cumulative number of drum rotations) and development bias when multiple development cartridges are replaced and used in conjunction with one drum cartridge. [Figure 6] Graph (a) shows the relationship between the cumulative number of drum rotations and the amount of blade bias correction, and graph (b) shows the dot count (cumulative number of drum rotations) and blade bias when multiple developing cartridges are replaced and used for one drum cartridge. [Figure 7] Graph (a) shows the relationship between the cumulative number of drum rotations and the supply bias correction amount, and graph (b) shows the dot count (cumulative number of drum rotations) and the supply bias when multiple developing cartridges are replaced and used for one drum cartridge. [Figure 8] Graph (a) shows the relationship between the cumulative number of drum rotations and the amount of peripheral speed difference correction, and graph (b) shows the dot count (cumulative number of drum rotations) and peripheral speed difference when multiple developing cartridges are replaced and used for one drum cartridge. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0037] Next, an embodiment of the present disclosure will be described in detail with reference to the drawings as appropriate. 1, the image forming apparatus 1 is a monochrome laser printer. The image forming apparatus 1 includes an apparatus main body 2, a feeder unit 3, an image forming unit 4, and a control device 100.

[0038] The device body 2 is in the shape of a hollow case. The device body 2 has a pair of left and right side walls 21 and a front wall 22 connecting the side walls 21. The front wall 22 has a body opening 22A. The front wall 22 is provided with a front cover 23 that opens and closes the body opening 22A.

[0039] The feeder unit 3 includes a supply tray 31 and a supply mechanism 32. The supply tray 31 is detachably attached to the lower part of the apparatus main body 2. The supply mechanism 32 supplies the supply tray 31 and the sheet S in the supply tray 31 toward the image forming unit 4.

[0040] The image forming section 4 includes a scanner unit 5, a fixing device 7, a drum cartridge 8, and a toner cartridge 9.

[0041] The scanner unit 5 is provided in the upper part of the apparatus body 2, and includes a laser emitting unit, a polygon mirror, a lens, a reflecting mirror, etc. (not shown). The scanner unit 5 irradiates a laser beam onto the surface of a photoconductor drum 81 (described later) at high speed.

[0042] The control device 100 includes, for example, a CPU, RAM, ROM, and input / output circuits, and performs arithmetic processing based on information about the installed cartridges and programs and data stored in the ROM, thereby executing print control.

[0043] The drum cartridge 8 is disposed between the feeder section 3 and the scanner unit 5. The drum cartridge 8 is detachable from the device main body 2. Specifically, the drum cartridge 8 is detachable from the device main body 2 through a main body opening 22A that is opened and closed by a front cover 23 of the device main body 2. The toner cartridge 9 is detachable from the drum cartridge 8. The toner cartridge 9 is detachable from the device main body 2 in a state where it is assembled to the drum cartridge 8.

[0044] The life of the drum cartridge 8 is longer than the life of the toner cartridge 9. A long life here means that the total number of pages that can be printed or the total printable dot count is large. For this reason, multiple toner cartridges 9 can be replaced with one drum cartridge 8 for use. For example, three to five toner cartridges 9 can be replaced with one drum cartridge 8 for use.

[0045] The drum cartridge 8 has a frame 80, a photosensitive drum 81, a transfer roller 82, a charger 83, and a drum memory 85. The toner cartridge 9 can be attached to the frame 80. The photosensitive drum 81 is supported by the frame 80 so as to be rotatable.

[0046] The toner cartridge 9 has a housing 90, a developing roller 91, a supply roller 92, a blade 93, and a toner memory 95. The housing 90 contains toner therein. The developing roller 91 supplies toner to the photoconductor drum 81. The supply roller 92 supplies the toner in the housing 90 to the developing roller 91. The blade 93 regulates the layer thickness of the toner supplied to the developing roller 91.

[0047] In this drum cartridge 8, the surface of the rotating photosensitive drum 81 is uniformly charged by the charger 83, and then exposed to high-speed scanning of a laser beam from the scanner unit 5. This reduces the potential of the exposed portion, and an electrostatic latent image based on image data is formed on the surface of the photosensitive drum 81.

[0048] Next, the toner in the toner cartridge 9 is supplied to the electrostatic latent image on the photosensitive drum 81 by the rotationally driven developing roller 91, and a toner image is formed on the surface of the photosensitive drum 81. Thereafter, the sheet S is transported between the photosensitive drum 81 and the transfer roller 82, and the toner image carried on the surface of the photosensitive drum 81 is transferred onto the sheet S.

[0049] The fixing device 7 includes a heating roller 71 and a pressure roller 72. The pressure roller 72 is positioned opposite the heating roller 71. The pressure roller 72 presses the heating roller 71. The fixing device 7 thermally fixes the toner transferred onto the sheet S while the sheet S passes between the heating roller 71 and the pressure roller 72.

[0050] The sheet S on which the toner image has been thermally fixed by the fixing device 7 is conveyed to a paper discharge roller 24 disposed downstream of the fixing device 7, and is sent from the paper discharge roller 24 onto a paper discharge tray 25.

[0051] The drum memory 85 is a medium for storing information, such as an IC chip, but is not limited to an IC chip. The drum memory 85 stores the cumulative number of drum rotations of the photoconductor drum 81.

[0052] The toner memory 95 is a medium for storing information, such as an IC chip, but is not limited to an IC chip. For example, the cumulative number of rotations of the developing roller 91, a dot count which is the number of developed dots, and a remaining amount of toner are stored in the toner memory 95. In this embodiment, the toner memory 95 stores the cumulative dot count of used toner.

[0053] As shown in FIG. 2, the image forming apparatus 1 further includes a charging bias application circuit 210, a developing bias application circuit 220, a blade bias application circuit 230, a supply bias application circuit 240, a first motor 250, and a second motor 260.

[0054] In this embodiment, a positively charged toner is used. In response to the positively charged toner, the charging bias application circuit 210, the developing bias application circuit 220, the blade bias application circuit 230, and the supply bias application circuit 240 apply a positive potential bias.

[0055] The charging bias application circuit 210 applies a charging bias V T The bias value of the charging bias application circuit 210 is controlled by the control device 100. Specifically, as shown in FIG. 3, the control device 100 gradually increases the charging bias V T Increase the charging bias V T The relationship between the charge potential and the cumulative number of drum rotations (Figure 3) is determined based on previously acquired experimental data so that the surface potential of the photoconductor drum is constant. In this way, the charging performance of the photoconductor drum 81, which deteriorates as the cumulative number of drum rotations increases, is compensated for.

[0056] Returning to FIG. 2, the developing bias application circuit 220 applies a developing bias V G The control device 100 controls the developing bias V to be applied to the developing roller 91 in accordance with the cumulative drum rotation number and the cumulative dot count. G Determine.

[0057] Specifically, the developing bias V G is the development bias reference value V according to the cumulative dot count Gn and the development bias correction amount V according to the cumulative drum rotation number MGN It is determined by adding (V G =V Gn +V MGN ).

[0058] As shown in FIG. 4(a), the development bias reference value V Gn is V when the cumulative dot count is zero (n=0). G0 The reference value of the developing bias V GnAs the cumulative dot count increases, the absolute value of V gradually decreases. Here, the development bias reference value when the cumulative dot count is n is V Gn The reference value of the development bias is V Gn The relationship between the cumulative dot count and the toner amount (FIG. 4(a)) is determined based on previously acquired experimental data. In this way, the amount of toner moving from the developing roller 91 to the photoconductor drum 81 is kept constant as the dot count increases, even if the toner deteriorates.

[0059] As shown in FIG. 5(a), the development bias correction amount V MGN is zero when the cumulative number of drum rotations is zero (N=0). MGN is set so that its absolute value gradually increases as the cumulative number of drum rotations increases. Here, the development bias correction amount when the cumulative number of drum rotations is N is V MGN The development bias correction amount V MGN The relationship between the cumulative number of drum rotations (FIG. 5(a)) is determined based on previously acquired experimental data. In this way, the amount of toner adhering to the photoconductor drum 81 is made constant as the cumulative number of drum rotations increases, even if the photoconductor drum 81 deteriorates.

[0060] In this embodiment, a first toner cartridge, which is the first toner cartridge for one drum cartridge, is used to form an image, and then a second toner cartridge different from the first toner cartridge is used to form an image.Furthermore, the third, fourth, and fifth toner cartridges are used in the same procedure to form images.

[0061] As shown in FIG. 5B, the control device 100 controls the initial developing bias V G1 and a process of determining an initial developing bias V when an image is formed using the second toner cartridge. G2Similarly, the initial developing bias V G3 ,V G4 ,V G5 It is possible to perform a process of determining

[0062] The initial developing bias of the toner cartridge is determined based on the cumulative number of drum rotations. When the drum cartridge is new, the cumulative number of drum rotations is zero, so the initial developing bias V G1 =V G0 The initial developing bias V G2 is derived from the development bias correction amount shown in FIG. 1 When the development bias correction amount is V MG1 The initial developing bias V MG2 =V G0 +V MG1 It becomes.

[0063] In other words, the initial developing bias V G2 is the initial developing bias V of the first drum cartridge G1 In this embodiment, the initial developing bias V G2 is the initial development bias V G1 is greater than (|V G2 |>|V G1 |).

[0064] Similarly, when the third, fourth, and fifth toner cartridges are attached to the first drum cartridge and image formation is performed, the control device 100 increases the absolute value of the initial developing bias in accordance with the cumulative number of drum rotations (|V G5 |>|V G4 |>|V G3 |>|V G2 |).

[0065] After the initial developing bias is determined, the control device 100 adjusts the developing bias V applied to the developing roller 91 in accordance with the increase in the cumulative drum rotation number and the cumulative dot count. G Specifically, the control device 100 changes the developing bias V G Absolute value of |V G As the cumulative number of drum rotations increases, the absolute value of the developing bias |V G Gradually decrease |.

[0066] Returning to FIG. 2, the blade bias application circuit 230 applies a blade bias V B The control device 100 controls the blade bias V applied to the blade 93 in accordance with the cumulative dot count and the cumulative number of drum rotations. B Determine.

[0067] Specifically, the Blade Bias V B is the blade bias reference value V according to the cumulative dot count. Bn and the blade bias correction amount V according to the cumulative drum rotation number. MBN It is determined by adding (V B =V Bn +V MBN ).

[0068] As shown in Fig. 4(b), the blade bias reference value V Bn is V when the cumulative dot count is zero (n=0). B0 The blade bias reference value V Bn As the cumulative dot count increases, the absolute value of decreases gradually. Here, the blade bias reference value when the cumulative dot count is n is V Bn The blade bias reference value V Bn The relationship between the dot count and the cumulative dot count (FIG. 4(a)) is determined based on previously acquired experimental data. In this way, the amount of toner adhering to the developing roller 91 is kept constant even if the toner deteriorates and the fluidity of the toner decreases as the dot count increases.

[0069] As shown in Fig. 6(a), the blade bias correction amount V MBN is zero when the cumulative number of drum rotations is zero (N=0). The blade bias correction amount V MBN is set so that its absolute value gradually increases as the cumulative number of drum rotations increases. Here, the blade bias correction amount when the cumulative number of drum rotations is N is V MBN The blade bias correction amount V MBN The relationship between the cumulative number of drum rotations (FIG. 6(a)) is determined based on previously acquired experimental data. In this way, the amount of toner adhering to the photoconductor drum 81 is made constant as the cumulative number of drum rotations increases, even if the photoconductor drum 81 deteriorates.

[0070] As shown in FIG. 6B, the control device 100 determines the initial blade bias V B1 and a process of determining an initial blade bias V when an image is formed using the second toner cartridge. B2 Similarly, the initial blade bias V B3 ,V B4 ,V B5 It is possible to perform a process of determining

[0071] The initial blade bias of the toner cartridge is determined based on the cumulative number of drum rotations. When the drum cartridge is new, the cumulative number of drum rotations is zero, so the initial blade bias V B1 =V B0 The initial blade bias V of the second toner cartridge B2 is derived from the blade bias correction amount shown in FIG. 6(a). 1 When the blade bias correction amount is V MB1 The initial blade bias V of the second toner cartridge MB2 =VB0 +V MB1 It becomes.

[0072] That is, the initial blade bias V of the second drum cartridge B2 is the initial blade bias V of the first drum cartridge B1 In this embodiment, the initial blade bias V B2 is the initial blade bias V B1 is greater than (|V B2 |>|V B1 |).

[0073] Similarly, when the third, fourth, and fifth toner cartridges are attached to the first drum cartridge and image formation is performed, the control device 100 increases the absolute value of the initial blade bias in accordance with the cumulative number of drum rotations (|V B5 |>|V B4 |>|V B3 |>|V B2 |).

[0074] After the initial blade bias is determined, the control device 100 adjusts the blade bias V applied to the developing roller 91 in accordance with the increase in the cumulative drum rotation number and the cumulative dot count. B Specifically, the control device 100 changes the developing bias V B Absolute value of |V B As the cumulative number of drum rotations increases, the absolute value of the blade bias |V B Gradually decrease |.

[0075] Returning to FIG. 2, the supply bias application circuit 240 applies a supply bias V K The control device 100 controls the supply bias V applied to the supply roller 92 in accordance with the cumulative dot count and the cumulative number of drum rotations. K Determine.

[0076] Specifically, the supply bias V Kis the supply bias reference value V according to the cumulative dot count Kn and the supply bias correction amount V according to the cumulative drum rotation number. MKN It is determined by adding (V K =V Kn +V MKN ).

[0077] As shown in Figure 4(c), the supply bias reference value V Kn is V when the cumulative dot count is zero (n=0). K0 The supply bias reference value V Kn As the cumulative dot count increases, the absolute value of gradually increases. Here, the supply bias reference value when the cumulative dot count is n is V Kn The supply bias reference value V Kn The relationship between the cumulative dot count and the toner charge amount (FIG. 4(c)) is determined based on previously acquired experimental data. In this way, as the dot count increases, the amount of toner adhering to the developing roller 91 is compensated for to be constant even if the toner deteriorates and the charging performance of the toner decreases.

[0078] As shown in FIG. 7(a), the supply bias correction amount V MKN is zero when the cumulative number of drum rotations is zero (N=0). The supply bias correction amount V MKN is set so that its absolute value gradually increases as the cumulative number of drum rotations increases. Here, the supply bias correction amount when the cumulative number of drum rotations is N is V MKN The supply bias correction amount V MKN The relationship between the cumulative number of drum rotations (FIG. 7(a)) is determined based on previously acquired experimental data. In this way, the amount of toner adhering to the photoconductor drum 81 is made constant as the cumulative number of drum rotations increases, even if the photoconductor drum 81 deteriorates.

[0079] As shown in FIG. 7B, the control device 100 controls the initial supply bias V K1and a process of determining an initial supply bias V when an image is formed using the second toner cartridge. K2 Similarly, the initial supply bias V K3 ,V K4 ,V K5 It is possible to perform a process of determining

[0080] The initial supply bias of the toner cartridge is determined based on the cumulative drum rotation number. When the drum cartridge is new, the cumulative drum rotation number is zero, so the initial supply bias V K1 =V K0 The initial supply bias V of the second toner cartridge K2 is derived from the supply bias correction amount shown in FIG. 1 When the supply bias correction amount is V MK1 The initial supply bias V MK2 =V K0 +V MK1 It becomes.

[0081] That is, the initial supply bias V of the second drum cartridge K2 is the initial supply bias V of the first drum cartridge. K1 In this embodiment, the initial supply bias V K2 is the initial supply bias V K1 is greater than (|V K2 |>|V K1 |).

[0082] Similarly, when the third, fourth, and fifth toner cartridges are attached to the first drum cartridge and image formation is performed, the control device 100 increases the absolute value of the initial supply bias in accordance with the cumulative drum rotation number (|V K5 |>|V K4 |>|V K3 |>|V K2 |).

[0083] After the initial supply bias is determined, the control device 100 adjusts the supply bias V applied to the developing roller 91 in accordance with the increase in the cumulative drum rotation number and the cumulative dot count. K Specifically, the control device 100 changes the supply bias V K Absolute value of |V K As the cumulative number of drum rotations increases, the absolute value of the supply bias |V K Gradually increase |.

[0084] Returning to FIG. 2, the first motor 250 is a drive source for supplying a drive force to the photoconductor drum 81. The speed of the first motor 250 is controlled by the control device 100. The second motor 260 is a drive source for supplying a drive force to the developing roller 91. The speed of the second motor 260 is controlled by the control device 100. The control device 100 determines the peripheral speed difference ΔV between the developing roller 91 and the photoconductor drum 81 in response to an increase in the cumulative dot count and the cumulative number of drum rotations.

[0085] Since the motors for driving the photosensitive drum 81 and the developing roller 91 are independent of each other, the control device 100 controls the peripheral speed V D and the peripheral speed V of the developing roller 91 E In this embodiment, the difference between the peripheral speed V of the photoconductor drum 81 and the peripheral speed V of the photoconductor drum 81 can be appropriately changed. D is set as a constant speed, and the peripheral speed of the developing roller 91 is V E The peripheral speed V of the developing roller 91 is changed. E is the peripheral speed V of the photoconductor drum 81 D That's it. E ≧V D In the following description, the peripheral speed V of the developing roller 91 is E and the peripheral speed V of the photoconductor drum 81. D Difference in peripheral speed V E -V D is simply called the "circumferential speed difference ΔV."

[0086] Specifically, the peripheral speed difference ΔV is a peripheral speed difference reference value ΔV according to the cumulative dot count. nand the peripheral speed difference correction amount ΔV according to the cumulative drum rotation number MN It is determined by adding (ΔV = ΔV n +ΔV MN ).

[0087] As shown in Fig. 4(d), the reference value of the peripheral speed difference ΔV n is ΔV when the cumulative dot count is zero (n=0). 0 The reference value of the peripheral speed difference ΔV n As the cumulative dot count increases, the absolute value of ΔV gradually decreases. Here, the reference value of the peripheral speed difference when the cumulative dot count is n is n The reference peripheral speed difference value ΔV n The relationship between the cumulative dot count and the cumulative dot count (FIG. 4(d)) is determined based on previously acquired experimental data. In this way, the amount of toner transported from the developing roller 91 to the photoconductor drum 81 is kept constant even if the toner deteriorates as the dot count increases.

[0088] As shown in FIG. 8(a), the peripheral speed difference correction amount ΔV MN is zero when the cumulative number of drum rotations is zero (N=0). MN is set so that its absolute value gradually increases as the cumulative number of drum rotations increases. Here, the peripheral speed difference correction amount when the cumulative number of drum rotations is N is ΔV MN The peripheral speed difference correction amount ΔV MN The relationship between the cumulative number of drum rotations (FIG. 8(a)) is determined based on previously acquired experimental data. In this way, the amount of toner adhering to the photoconductor drum 81 is made constant as the cumulative number of drum rotations increases, even if the photoconductor drum 81 deteriorates.

[0089] As shown in FIG. 8B, the control device 100 calculates the initial peripheral speed difference ΔV 1 and a process of determining the initial peripheral speed difference ΔV when image formation is performed with the second toner cartridge. 2Similarly, the initial peripheral speed difference ΔV when image formation is performed with the third, fourth, and fifth toner cartridges can be determined. 3 ,ΔV 4 ,ΔV 5 It is possible to perform a process of determining

[0090] The initial peripheral speed difference ΔV of the toner cartridge is determined based on the cumulative number of drum rotations. When the drum cartridge is new, the cumulative number of drum rotations is zero, so the initial peripheral speed difference ΔV of the first drum cartridge is 1 = ΔV 0 The initial peripheral speed difference ΔV of the second toner cartridge 2 is derived from the peripheral speed difference correction amount shown in FIG. 1 When the peripheral speed difference correction amount is ΔV M1 The initial peripheral speed difference ΔV of the second toner cartridge 2 = ΔV 0 +ΔV M1 It becomes.

[0091] That is, the initial peripheral speed difference ΔV of the second drum cartridge 2 is the initial peripheral speed difference ΔV of the first drum cartridge 1 In this embodiment, the initial peripheral speed difference ΔV 2 is the initial peripheral speed difference ΔV 1 It is larger than (ΔV 2 >ΔV 1 ).

[0092] Similarly, when the third, fourth, and fifth toner cartridges are attached to the first drum cartridge and image formation is performed, the control device 100 increases the initial peripheral speed difference in accordance with the cumulative number of drum rotations (ΔV 5 >ΔV 4 >ΔV 3 >ΔV 2 ).

[0093] After the initial circumferential speed difference ΔV is determined, the control device 100 changes the circumferential speed difference ΔV applied to the development roller 91 as the cumulative drum rotation count and the cumulative dot count increase. Specifically, the control device 100 gradually decreases the circumferential speed difference ΔV as the cumulative dot count increases, and gradually decreases the circumferential speed difference ΔV as the cumulative drum rotation count increases.

[0094] According to the image forming apparatus 1 of the present embodiment as described above, the following effects are achieved.

[0095] According to the image forming apparatus 1, the initial developing bias V G1 and initial development bias V G2 (Specifically, |V K2 |>|V K1 By setting the second toner cartridge to the first toner cartridge, the amount of toner adhering to the photosensitive drum when the second toner cartridge is used can be made to approach the amount of toner adhering to the photosensitive drum when the first toner cartridge is used. Therefore, even if multiple toner cartridges are replaced with one drum cartridge, the print density of the image forming device 1 can be stabilized.

[0096] In addition, the control device 100 changes the developing bias applied to the developing roller 91 in response to an increase in the cumulative drum rotation number and the cumulative dot count, so that the developing bias can be changed in response to both deterioration of the photosensitive drum 81 and toner deterioration. For example, the charging performance of the photoconductor drum 81 decreases with deterioration, so it is advisable to gradually increase the developing bias to compensate for the decrease in charging performance. On the other hand, the adhesive force of the toner increases with deterioration, so it is advisable to gradually decrease the developing bias to prevent excessive adhesion. By changing the developing bias in response to both of these, the amount of toner adhering to the photoconductor drum 81 can be kept constant.

[0097] Also, the initial blade bias V B1 and initial blade bias V B2By making the toner amount of the developing roller 91 of the second toner cartridge different from the toner amount of the developing roller 91 of the first toner cartridge, the amount of toner that adheres to the developing roller 91 of the second toner cartridge can be made closer to the amount of toner that adheres to the developing roller 91 of the first toner cartridge. Therefore, the amount of toner that is supplied from the developing roller 91 to the photoconductor drum 81 is stabilized. As a result, the print density of the image forming apparatus 1 can be stabilized.

[0098] Furthermore, the control device 100 changes the blade bias applied to the developing roller 91 in response to an increase in the cumulative drum rotation number and the cumulative dot count, so that the developing bias can be changed in response to both the deterioration of the photoconductor drum 81 and the deterioration of the toner. Therefore, the amount of toner adhering to the photoconductor drum 81 can be kept constant.

[0099] In addition, the initial supply bias V K1 and the initial supply bias V K2 By making the developing roller 91 of the second toner cartridge different from the developing roller 91 of the first toner cartridge, the amount of toner adhering to the developing roller 91 of the second toner cartridge can be made closer to the amount of toner adhering to the developing roller 91 of the first toner cartridge. This stabilizes the amount of toner supplied from the developing roller 91 to the drum cartridge 8. As a result, the print density of the image forming apparatus 1 can be stabilized.

[0100] Furthermore, the control device 100 changes the supply bias applied to the supply roller 92 in response to an increase in the cumulative drum rotation number and the cumulative dot count, so that the supply bias can be changed in response to deterioration of the photoconductor drum 81 and toner deterioration. Therefore, the amount of toner supplied to the photoconductor drum 81 can be kept constant.

[0101] In addition, the initial peripheral speed difference ΔV 1 and the initial peripheral speed difference ΔV 2By making the amount of toner adhered to the photosensitive drum when the second toner cartridge is used different from the amount of toner adhered to the photosensitive drum when the first toner cartridge is used, the amount of toner supplied from the developing roller 91 to the drum cartridge 8 is stabilized. As a result, the print density of the image forming apparatus 1 can be stabilized.

[0102] Furthermore, the control device 100 changes the peripheral speed difference between the developing roller 91 and the photosensitive drum 81 in response to an increase in the cumulative drum rotation number and the cumulative dot count, so that the peripheral speed difference can be changed in response to deterioration of the photosensitive drum 81 and toner deterioration. Therefore, the amount of toner supplied to the photosensitive drum 81 can be kept constant.

[0103] The present disclosure is not limited to the above-described embodiment, but can be used in various forms as exemplified below.

[0104] In the above embodiment, positively charged toner is used, but negatively charged toner may be used. In this case, the charging bias application circuit 210, the developing bias application circuit 220, the blade bias application circuit 230, and the supply bias application circuit 240 may apply a negative potential bias.

[0105] In the above-described embodiment, the control device 100 controls the developing bias V G Absolute value of |V G In the above example, | was set small, but the bias value may be determined according to the cumulative number of drum rotations or the amount of toner remaining, instead of the cumulative dot count. Similarly, the peripheral speed difference ΔV between the photosensitive drum and the developing roller may be determined according to the cumulative number of drum rotations or the amount of toner remaining, instead of the cumulative dot count.

[0106] In the above-described embodiment, the peripheral speed of the photosensitive drum 81 is constant, but it may be changed. Also, the peripheral speed of the developing roller 91 is equal to or higher than the peripheral speed of the photosensitive drum, but it may be set to be lower than the peripheral speed of the photosensitive drum.

[0107] In the above-described embodiment, the photoconductor drum 81 and the developing roller 91 are driven by separate motors, but they may be driven by a single motor. In this case, the developing roller and the motor may be connected via a transmission mechanism capable of changing the speed transmission ratio.

[0108] In the above-described embodiment, a monochrome laser printer has been exemplified as the image forming apparatus, but the image forming apparatus may be a color laser printer, a copier, or a multifunction machine.

[0109] The elements described in the above-mentioned embodiment and modified examples can also be implemented in any combination. [Explanation of symbols]

[0110] 1. Image forming device 2. Device body 4. Image forming section 8 Drum Cartridge 9 Toner Cartridge 81 Photoconductor drum 85 Drum Memory 91 Developing roller 92 Supply roller 93 Blade 95 Toner Memory 100 Control device V B Blade Bias V B1 Initial Blade Bias V B2 Initial Blade Bias V G Development Bias V G1 Initial Development Bias V G2 Initial Development Bias V K Supply bias V K1 Initial supply bias V K2 Initial supply bias ΔV peripheral speed difference ΔV 1 Initial peripheral speed difference ΔV 2 Initial peripheral speed difference

Claims

1. An image forming apparatus, A device body, a drum cartridge having a photosensitive drum and a drum memory for storing a cumulative number of rotations of the photosensitive drum, the drum cartridge being detachable from the main body of the apparatus; a toner cartridge having a developing roller and a toner memory for storing a cumulative dot count; A control device, The control device includes: a process of determining an initial developing bias VG1 to be applied to the developing roller when an image is formed by using the first toner cartridge for the drum cartridge, based on the cumulative number of drum rotations; a process of determining an initial developing bias VG2 different from the initial developing bias VG1 based on the cumulative drum rotation number further accumulated by the image formation performed using the first toner cartridge, when a second toner cartridge different from the first toner cartridge is used in the drum cartridge to form an image after the initial developing bias VG1 is determined; An image forming apparatus capable of executing the following: the control device changes a developing bias applied to the developing roller in response to an increase in the cumulative drum rotation number and the cumulative dot count; |VG2|>|VG1|, The image forming apparatus is characterized in that, while one of the toner cartridges is being used to form an image, the control device reduces the absolute value of the developing bias as the cumulative number of drum rotations increases.

2. 2. The image forming apparatus according to claim 1, wherein the control device reduces an absolute value of the developing bias as the cumulative dot count increases.

3. the toner cartridge includes a blade for regulating a thickness of a layer of toner supplied to the developing roller, The control device includes: When the first toner cartridge is used for the drum cartridge to form an image, the first toner cartridge is A process of determining an initial blade bias VB1 to be applied to the blade when an image is formed; a process of determining an initial blade bias VB2 different from the initial blade bias VB1 based on the cumulative drum rotation count further accumulated by the image formation performed using the first toner cartridge, when a second toner cartridge different from the first toner cartridge is used in the drum cartridge to form an image after the initial blade bias VB1 is determined; An image forming apparatus capable of executing the control device changes a blade bias applied to the blade in response to an increase in the cumulative drum rotation number and the cumulative dot count; |VB2|>|VB1|, 3. The image forming apparatus according to claim 1, wherein the control device reduces the absolute value of the blade bias as the cumulative number of drum rotations increases while one toner cartridge is being used to form an image.

4. 4. The image forming apparatus according to claim 3, wherein the control device reduces the absolute value of the blade bias as the cumulative dot count increases.

5. a supply roller for supplying toner to the developing roller, The control device includes: a process of determining an initial supply bias VK1 to be applied to the supply roller when an image is formed by using the first toner cartridge for the drum cartridge, based on the cumulative number of drum rotations; a process of determining an initial supply bias VK2 different from the initial supply bias VK1 based on the cumulative drum rotation number further accumulated by the image formation performed using the first toner cartridge, when a second toner cartridge different from the first toner cartridge is used for the drum cartridge to form an image after the initial supply bias VK1 is determined; An image forming apparatus capable of executing the control device changes a supply bias applied to the supply roller in response to an increase in the cumulative drum rotation number and the cumulative dot count; |VK2|>|VK1|, 5. The image forming apparatus according to claim 1, wherein the control device increases the absolute value of the supply bias as the cumulative number of drum rotations increases while one toner cartridge is being used to form an image.

6. 6. The image forming apparatus according to claim 5, wherein the control device increases the absolute value of the supply bias as the cumulative dot count increases.

7. The control device includes: When a first toner cartridge is used for forming an image with respect to the drum cartridge, a process of determining an initial peripheral speed difference ΔV1 between the developing roller and the photosensitive drum when an image is formed with the first toner cartridge based on the cumulative number of drum rotations; a process for determining an initial circumferential speed difference ΔV2 different from the initial circumferential speed difference ΔV1 based on the cumulative drum rotation count further accumulated by the image formation performed using the first toner cartridge, when a second toner cartridge different from the first toner cartridge is used in the drum cartridge to form an image on the drum cartridge after the initial circumferential speed difference ΔV1 is determined; An image forming apparatus capable of executing the following: the control device changes a peripheral speed difference between the developing roller and the photosensitive drum in response to an increase in the cumulative drum rotation number and the cumulative dot count; ΔV2>ΔV1, 7. The image forming apparatus according to claim 1, wherein the control device reduces the peripheral speed difference as the cumulative number of drum rotations increases while one toner cartridge is being used to form an image.

8. 8. The image forming apparatus according to claim 7, wherein the control device reduces the peripheral speed difference as the cumulative dot count increases.

9. 9. The image forming apparatus according to claim 1, wherein the toner cartridge is detachable from the drum cartridge.

Images