Patent Application
20210141336
The present disclosure relates to an image forming apparatus to which a drum cartridge and a toner cartridge are detachably attachable.
There has been conventionally known an image forming apparatus to which a drum cartridge and a toner cartridge are detachably attachable. In the conventional image forming apparatus, the drum cartridge is mounted on the image forming apparatus after the toner cartridge is attached to the drum cartridge.
Generally, the lifetime of a drum cartridge is longer than the lifetime of a toner cartridge. Accordingly, a plurality of toner cartridges are used in succession with respect to a single drum cartridge such that when toner runs out in one toner cartridge, for example, the toner cartridge is replaced with the next toner cartridge.
However, if the initial toner cartridge and the subsequent toner cartridges are used under the same conditions, the amount of toner supplied from a toner cartridge to the drum cartridge may vary among the respective toner cartridges, failing to stabilize print density.
The disclosure has been made in view of the above-described problem and an object thereof is to stabilize the print density of an image forming apparatus.
According to one aspect, the disclosure provides an image forming apparatus including an apparatus body, a controller, a drum cartridge and a toner cartridge. The drum cartridge is detachably attachable to the apparatus body. The drum cartridge includes a photosensitive drum and a drum memory. The drum memory stores data of a cumulative number of drum rotations of the photosensitive drum. The toner cartridge is configured to be used to perform image formation together with the drum cartridge. A first toner cartridge is used as the toner cartridge, before a second toner cartridge is used as the toner cartridge. The toner cartridge includes a developing roller and a toner memory. The developing roller is configured to be applied with a developing bias. A first developing bias is the developing bias applied to the developing roller of the first toner cartridge. A second developing bias is the developing bias applied to the second toner cartridge. The toner memory stores data of a cumulative dot count. An initial developing bias is the developing bias that is applied to the developing roller of the toner cartridge when the cumulative dot count stored in the toner memory of the toner cartridge is equal to zero. A first initial developing bias is the initial developing bias for the first toner cartridge. A second initial developing bias is the initial developing bias for the second toner cartridge. The controller is configured to perform determining a value of the first initial developing bias based on the cumulative number of drum rotations that is stored in the drum memory at the time when the cumulative dot count stored in the toner memory of the first toner cartridge is equal to zero. After determining the first initial developing bias, the controller is configured to perform determining a value of the second initial developing bias based on the cumulative number of drum rotations that is stored in the drum memory at the time when the cumulative dot count stored in the toner memory of the second toner cartridge is equal to zero. The value of the second initial developing bias is different from the value of the first initial developing bias.
According to another aspect, the disclosure provides an image forming apparatus including an apparatus body, a controller, a drum cartridge and a toner cartridge. The drum cartridge is detachably attachable to the main body. The drum cartridge includes a photosensitive drum, at least one of a transfer roller and a cleaning roller and a drum memory. Each of the transfer roller and the cleaning roller faces the photosensitive drum. The transfer roller is configured to be applied with a transfer current. The cleaning roller is configured to be applied with a cleaning bias. The drum memory stores data of a cumulative number of drum rotations of the photosensitive drum. The toner cartridge is configured to be used to perform image formation together with the drum cartridge. A first toner cartridge is used as the toner cartridge before a second toner cartridge is used as the toner cartridge. A first transfer current is the transfer current applied to the transfer roller when the first toner cartridge is used. A second transfer current is the transfer current applied to the transfer roller when the second toner cartridge is used. A first cleaning bias is the cleaning bias applied to the cleaning roller when the first toner cartridge is used. A second cleaning bias is the cleaning bias applied to the cleaning roller when the second toner cartridge is used. The toner cartridge includes a cartridge housing, a developing roller and a toner memory. The cartridge housing accommodates toner therein. The toner memory stores data of a cumulative dot count. An initial transfer current is the transfer current that is applied to the transfer roller when the cumulative dot count stored in the toner memory of the toner cartridge is equal to zero. A first initial transfer current is the initial transfer current that is applied to the transfer roller when the first toner cartridge is used. A second initial transfer current is the initial transfer current that is applied to the transfer roller when the second toner cartridge is used. An initial cleaning bias is the cleaning bias that is applied to the cleaning roller of the drum cartridge when the cumulative dot count stored in the toner memory of the toner cartridge is equal to zero. A first initial cleaning bias is the initial cleaning bias when the first toner cartridge is used. A second initial cleaning bias is the initial cleaning bias when the second toner cartridge is used. In a case where the drum cartridge includes the transfer roller, the controller is configured to perform determining a value of the first initial transfer current based on the cumulative number of drum rotations that is stored in the drum memory at the time when the cumulative dot count stored in the toner memory of the first toner cartridge is equal to zero. After determining the first initial transfer current, the controller is configured to perform determining a value of the second initial transfer current based on the cumulative number of drum rotations that is stored in the drum memory at the time when the cumulative dot count stored in the toner memory of the second toner cartridge is equal to zero. The value of the second initial transfer current is different from the value of the first initial transfer current. In a case where the drum cartridge includes the cleaning roller, the controller is configured to perform determining a value of the initial cleaning bias based on the cumulative number of drum rotations that is stored in the drum memory at the time when the cumulative dot count stored in the toner memory of the first toner cartridge is equal to zero. After determining the first initial cleaning bias, the controller is configured to perform determining a value of the second initial cleaning bias based on the cumulative number of drum rotations that is stored in the drum memory at the time when the cumulative dot count stored in the toner memory of the second toner cartridge is equal to zero. The value of the second initial cleaning bias is different from the value of the first initial cleaning bias.
The particular features and advantages of the disclosure will become apparent from the following description taken in connection with the accompanying drawings, in which:
Hereinafter, a first embodiment of the present disclosure will be described in detail with reference to
As illustrated in
The apparatus body 2 is a case formed into a hollow shape. The apparatus 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 an opening 22A. The front wall 22 is provided with a front cover 23 for opening/closing the opening 22A.
The feeder part 3 has a feed tray 31 and a feed mechanism 32. The feed tray 31 is detachably attached to a lower portion of the apparatus body 2. The feed mechanism 32 feeds a sheet S stored in the feed tray 31 toward the image forming part 4.
The image forming part 4 has a scanner unit 5, a fixing device 7, a drum cartridge 8, and a toner cartridge 9.
The scanner unit 5 is provided at an upper part of the apparatus body 2 and includes a laser emitting part, a polygon mirror, a lens, and a reflecting mirror, which are not illustrated. The scanner unit 5 irradiates the surface of a photosensitive drum 81 (described later) with laser beam in a high-speed scanning motion.
The controller 100 has, for example, a CPU, a RAM, a ROM, and an input/output circuit. The controller 100 performs arithmetic processing based on information related to the attached cartridge or program/data stored in the ROM to thereby execute print control. As described later, data shown in
The drum cartridge 8 is detachably attached to the apparatus body 2 of the image forming apparatus 1. Specifically, the drum cartridge 8 is detachably attached to the apparatus body 2 through the opening 22A opened by the front cover 23 of the apparatus body 2. The drum cartridge 8 is disposed at a position between the feeder part 3 and the scanner unit 5 when the drum cartridge 8 is attached to the apparatus body 2. The toner cartridge 9 is detachably attached to the drum cartridge 8. The toner cartridge 9 is detached from or attached to the apparatus body 2 in a state where the toner cartridge 9 has been assembled to the drum cartridge 8. That is, when the toner cartridge 9 is replaced with a next one, the drum cartridge 8 and the toner cartridge 9 are integrally removed from and attached to the image forming apparatus 1.
The lifetime of the drum cartridge 8 is longer than the lifetime of the toner cartridge 9. Here, the lifetime is determined from the total number of prints or the total number of printable dots. Thus, while the same, single drum cartridge 8 is used, a plurality of different toner cartridges 9 are used in succession such that when the lifetime of a toner cartridge 9 currently attached to the drum cartridge 8 has been reached, the toner cartridge 9 is replaced with a new one. For example, three to five toner cartridges 9 may be used in succession for one drum cartridge 8. This means that the lifetime of the drum cartridge 8 is approximately three to five times as long as the lifetime of the toner cartridge 9.
In the present embodiment, while one drum cartridge 8 is used in the image forming apparatus 1, a plurality of toner cartridges 9 are used in succession. A toner cartridge 9 that is used first among the plurality of toner cartridges 9 will be referred to as a first toner cartridge 9. A toner cartridge 9 that is used second among the plurality of toner cartridge 9 will be referred to as a second toner cartridge 9. A toner cartridge 9 that is used third among the plurality of toner cartridges 9 will be referred to as a third toner cartridge 9. A toner cartridge 9 that is used fourth among the plurality of toner cartridges 9 will be referred to as a fourth toner cartridge 9. A toner cartridge 9 that is used fifth among the plurality of toner cartridges 9 will be referred to as a fifth toner cartridge 9. To summarize, a toner cartridge 9 that is used X-th in the series of the toner cartridge 9 (where X is an integer greater than zero (0)) will be referred to as an X-th toner cartridge 9.
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 detachably attached to the frame 80. The photosensitive drum 81 is rotatably supported by the frame 80.
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 stores toner therein. The supply roller 92 supplies toner stored in the housing 90 to the developing roller 91. The developing roller 91 supplies toner to the photosensitive drum 81. The blade 93 restricts the layer thickness of the toner supplied to the developing roller 91.
In the drum cartridge 8, while the photosensitive drum 81 is rotating, the surface of the photosensitive drum 81 is uniformly charged by the charger 83 and then exposed by the high-speed scanning of the laser beam from the scanner unit 5. As a result, the potential of the exposed portion decreases and an electrostatic latent image based on image data is formed on the surface of the photosensitive drum 81.
Subsequently, the toner stored in the toner cartridge 9 is supplied to the electrostatic latent image on the photosensitive drum 81 by the rotationally driven developing roller 91, whereby a toner image is formed on the surface of the photosensitive drum 81. Thereafter, a sheet S is conveyed to a position 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.
The fixing device 7 has a heating roller 71 and a pressing roller 72. The pressing roller 72 is positioned so as to face the heating roller 71. The pressing roller 72 presses the heating roller 71. The fixing device 7 thermally fixes the toner image transferred onto the sheet S while the sheet S is passing between the heating roller 71 and the pressing roller 72.
The sheet S onto which the toner image has been thermally fixed by the fixing device 7 is conveyed to a sheet discharge roller 24 provided downstream from the fixing device 7 and then fed onto a sheet discharge tray 25 by the sheet discharge roller 24.
The drum memory 85 of the drum cartridge 8 is a medium that stores information of the drum cartridge 8. The drum memory 83 is, for example, an IC chip, but is not limited to the IC chip. The drum memory 85 stores therein data of a cumulative number of drum rotations “N” of the photosensitive drum 81 that is counted by the controller 100. Here, the cumulative number of drum rotations “N” indicates how many times the photosensitive drum 81 has been rotated since the drum cartridge 8 was newly attached to the image forming apparatus 1 and while the drum cartridge 8 has been used in the image forming apparatus 1. In other words, the cumulative number of drum rotations “N” is the total number of drum rotations that have been attained since the drum cartridge 8 was newly attached to the image forming apparatus 1 and while the drum cartridge 8 has been used in the image forming apparatus 1. Even when the drum cartridge 8 is removed from the image forming apparatus 1 and attached to the image forming apparatus 1 again before the lifetime of the drum cartridge 8 has been reached, the controller 100 continues updating the cumulative number of drum rotations “N” without initializing the cumulative number of drum rotations “N”. As described later, it is noted that charging capability of the photosensitive drum 81 degrades as the cumulative number of drum rotations “N” increases.
The toner memory 95 of the toner cartridge 9 is a medium that stores information of the toner cartridge 9. The toner memory 95 is, for example, an IC chip, but is not limited to the IC chip. The toner memory 95 stores therein, for example, a cumulative number of rotations of the developing roller 91, a cumulative dot count “n” which is the cumulative number of developed dots counted by the controller 100, and a toner residual amount. In the present embodiment, the toner memory 95 stores at least the cumulative dot count “n”. Here, the cumulative dot count “n” indicates the accumulated number of dots that have been developed since the toner cartridge 9 was newly mounted in the image forming apparatus 1 and while the toner cartridge 9 has been used. In other words, the cumulative dot count is the total number of dots that have been attained since the toner cartridge 9 was newly mounted in the image forming apparatus 1 and while the toner cartridge 9 has been used. Even when the toner cartridge 9 is removed from the image forming apparatus 1 and attached to the image forming apparatus 1 again before the lifetime of the toner cartridge 9 has been reached, the controller 100 continues updating the cumulative dot count “n” without initializing the cumulative dot count “n”.
As illustrated in
In the present embodiment, positively charged type toner is used. Correspondingly, the charging bias application circuit 210, developing bias application circuit 220, blade bias application circuit 230, and supply bias application circuit 240 are each applied with positive bias voltage.
The charging bias application circuit 210 is a circuit for applying a charging bias VT to the charger 83. The value of the charging bias applied by the charging bias application circuit 210 is controlled by the controller 100. Specifically, as illustrated in
Referring back to
Specifically, the controller 100 determines the value of the developing bias VGX for an X-th toner cartridge 9 by adding a developing bias reference value VG(n), which varies according to the cumulative dot count “n”, and a developing bias correction amount VMG(N), which varies according to the cumulative number of drum rotations “N” (VGX(n, N)=VG(n)+VMG(N)), wherein X is an integer greater than zero (0).
As illustrated in
When the lifetime of the first toner cartridge 9 is reached, the first toner cartridge 9 is replaced with the second toner cartridge 9. In the example of
Similarly, as the third, fourth, and fifth toner cartridges 9 are attached to the same drum cartridge 8 in this order to perform image formation, the controller 100 execute processings of determining initial developing biases VG3(n=0, N=N2), VG4(n=0, N=N3), and VG5(n=0, N=N4) for the third, fourth and fifth toner cartridges 9 by calculating formulas: VG(n=0)+VMG(N=N2), VG(n=0)+VMG(N=N3), and VG(n=0)+VMG(N=N4), respectively. The controller 100 determines the initial developing bias for the third, fourth and fifth toner cartridges 9 such that the absolute value of the initial developing bias increases according to the cumulative number of drum rotations “N”. That is, |VG5(n=0, N=N4)|>|VG4(n=0, N=N3)|>|VG3(n=0, N=N2)|>|VG2(n=0, N=N1)|.
As illustrated in
Referring back to
Specifically, the controller 100 determines the value of the blade bias VBX for the X-th toner cartridge 9 by adding a blade bias reference value VB(n), which varies according to the cumulative dot count “n”, and a blade bias correction amount VMB(N), which varies according to the cumulative number of drum rotations “N” (VBX(n, N)=VB(n)+VMB(N)), wherein X is an integer greater than zero (0).
As illustrated in
As described above, at the timing when the second toner cartridge 9 is newly attached to the drum cartridge 8, the cumulative number of drum rotations “N” is equal to N1 and the cumulative dot counts n is equal to zero (0). At this time, the controller 100 determines the initial blade bias VB2(n=0, N=N1) for the second toner cartridge 9 based on the blade bias reference value VB(n=0) and the developing bias correction amount VMB(N=N1). Specifically, the controller 100 determines the initial blade bias VB2(n=0, N=N1) for the second toner cartridge 9 by calculating the formula of VB(n=0)+VMB(N=N1). Thus, the initial blade bias VB2(n=0, N=N1) of the second toner cartridge 9 differs from the initial blade bias VB1(n=0, N=0) for the first toner cartridge 9 (see
Similarly, as the third, fourth, and fifth toner cartridges 9 are attached to the same drum cartridge 8 in this order to perform image formation, the controller 100 executes processings of determining initial blade biases VB3(n=0, N=N2), VB4(n=0, N=N3), and VB5(n=0, N=N4) for the third, fourth and fifth toner cartridges 9 by calculating formulas: VB(n=0)+VMB(N=N2), VB(n=0)+VMB(N=N3), and VB(n=0)+VMB(N=N4), respectively. The controller 100 determines the initial blade bias for the third, fourth and fifth toner cartridges 9 such that the absolute value of the initial blade bias increases according to the cumulative number of drum rotations “N”. That is, |VB5(n=0, N=N4)|>|VB4(n=0, N=N3)|>|VB3(n=0, N=N2)|>|VB2(n=0, N=N1)|.
As illustrated in
Referring back to
Specifically, the controller 100 determines the value of the supply bias VKX for the X-th toner cartridge 9 by adding a supply bias reference value VK(n), which varies according to the cumulative dot count “n”, and a supply bias correction amount VMK(N), which varies according to the cumulative number of drum rotations “N” (VKX(n, N)=VK(n)+VMK(N)), wherein X is an integer greater than zero (0).
As illustrated in
As described above, at the timing when the second toner cartridge 9 is newly attached to the drum cartridge 8, the cumulative number of drum rotations “N” is equal to N1 and the cumulative dot counts n is equal to zero (0). At this time, the controller 100 determines the initial supply bias VK2(n=0, N=N1) for the second toner cartridge 9 based on the supply bias reference value VK(n=0) and the supply bias correction amount VMK(N=N1). Specifically, the controller 100 determines the initial supply bias VK2(n=0, N=N1) for the second toner cartridge 9 by calculating the formula of VK(n=0)+VMK(N=N1). Thus, the initial supply bias VK2(n=0, N=N1) for the second toner cartridge 9 differs from the initial supply bias VK1(n=0, N=0) of the first toner cartridge 9. In the present embodiment, the absolute value of the initial supply bias VK2(n=0, N=N1) for the second toner cartridge 9 is larger than the absolute value of the initial supply bias VK1(n=0, N=0) for the first toner cartridge 9. That is, |VK2(n=0, N=N1)|>|VK1(n=0, N=0)|.
Similarly, as the third, fourth, and fifth toner cartridges 9 are attached to the same drum cartridge 8 in this order to perform image formation, the controller 100 executes processings of determining initial supply biases VK3(n=0, N=N2), VK4(n=0, N=N3), and VK5(n=0, N=N4) for the third, fourth and fifth toner cartridges 9 by calculating formulas: VK(n=0)+VMK(N=N2), VK(n=0)+VMK(N=N3), and VK(n=0)+VMK(N=N4), respectively. The controller 100 determines the initial supply bias for the third, fourth and fifth toner cartridges 9 such that the absolute value of the initial supply biases increases according to the cumulative number of drum rotations “N”. That is, |VK5(n=0, N=N4)|>|VK4(n=0, N=N3)|>VK3(n=0, N=N2)|>|VK2(n=0, N=N1)|.
As illustrated in
Referring back to
The motors 250 and 260 for driving the photosensitive drum 81 and developing roller 91 are independent from one another. Accordingly, when necessary, the controller 100 is able to change the difference between the circumferential velocity VD of the photosensitive drum 81 and the circumferential velocity VE of the developing roller 91 (i.e. the circumferential velocity difference ΔV). In the present embodiment, the circumferential velocity VD of the photosensitive drum 81 is made constant, and the circumferential velocity VE of the developing roller 91 is changed. The circumferential velocity VE of the developing roller 91 is equal to or higher than the circumferential velocity VD of the photosensitive drum 81 (VE VD). Hereinafter, the circumferential velocity difference VE−VD between the circumferential velocity VE of the developing roller 91 and the circumferential velocity VD of the photosensitive drum 81 is referred to merely as “circumferential velocity difference ΔV”.
Specifically, the controller 100 determines the value of the circumferential velocity difference ΔVX for an X-th toner cartridge 9 by adding a circumferential-velocity-difference reference value ΔV(n), which varies according to the cumulative dot count “n”, and a circumferential-velocity-difference correction amount ΔVM(N), which varies according to the cumulative number of drum rotations “N” (ΔVX(n, N)=ΔV(n)+ΔVM(N)), wherein X is an integer greater than zero (0).
As illustrated in
As described above, at the timing when the second toner cartridge 9 is newly attached to the drum cartridge 8, the cumulative number of drum rotations “N” is equal to N1, and the cumulative dot counts n is equal to zero (0). At this time, the controller 100 determines the initial circumferential velocity difference ΔV2(n=0, N=N1) for the second toner cartridge 9 based on the circumferential velocity difference reference value ΔV(n=0) and the circumferential velocity difference correction amount ΔVM(N=N1). Specifically, the controller 100 determines the initial circumferential velocity difference ΔV2(n=0, N=N1) of the second toner cartridge 9 by calculating the formula of ΔV(n=0)+ΔVM(N=N1). Thus, the initial circumferential velocity difference ΔV2(n=0, N=N1) for the second toner cartridge 9 differs from the initial circumferential velocity difference ΔV1(n=0, N=0) of the first toner cartridge 9. In the present embodiment, the initial circumferential velocity difference ΔV2(n=0, N=N1) for the second toner cartridge 9 is larger than the initial circumferential velocity difference ΔV1(n=0, N=0) for the first toner cartridge 9. That is, ΔV2(n=0, N=N1)>ΔV1(n=0, N=0).
Similarly, as the third, fourth, and fifth toner cartridges 9 are attached to the drum cartridge 8 in this order to perform image formation, the controller 100 executes processings of determining initial circumferential velocity differences ΔV3(n=0, N=N2), ΔV4(n=0, N=N3), and ΔV5(n=0, N=N4) for the third, fourth and fifth toner cartridges 9 by calculating formulas: ΔV(n=0)+ΔVM(N=N2), ΔV(n=0)+ΔVM(N=N3), and ΔV(n=0)+ΔVM(N=N4), respectively. The controller 100 determines the initial circumferential velocity difference for the third, fourth and fifth toner cartridges 9 such that the initial circumferential velocity differences increases according to the cumulative number of drum rotations “N”. That is, ΔV5(n=0, N=N4)>ΔV4(n=0, N=N3)>ΔV3(n=0, N=N2)>ΔV2(n=0, N=N1).
As illustrated in
According to the above-described image forming apparatus 1, the following advantages are achieved.
According to the image forming apparatus 1, by making the initial developing bias VG1(n=0, N=0) and the initial developing bias VG2(n=0, N=N1) different (specifically, by making |VG2(n=0, N=N1)| larger than |VG1(n=0, N=0)|), the amount of toner adhering to the photosensitive drum 81 when the second toner cartridge is used can be brought close to the amount of toner adhering to the photosensitive drum 81 when the first toner cartridge is used. This allows the print density of the image forming apparatus 1 to be stabilized while a plurality of toner cartridges are used in succession for one drum cartridge.
Further, the controller 100 changes the developing bias VGX(n, N) to be applied to the developing roller 91 according to an increase in the cumulative number of drum rotations “N” and to an increase in the cumulative dot count “n”, so that the developing bias can be changed according to both degradation of the photosensitive drum 81 and degradation of toner.
For example, the photosensitive drum 81 degrades in charging capability in accordance with degradation of the photosensitive drum 81. Accordingly, the developing bias should be gradually increased so as to compensate for the degradation in the charging capability. On the other hand, toner increases in adhesion force in accordance with degradation of toner. Accordingly, the developing bias should be gradually reduced so as to prevent excessive adhesion. By changing the developing bias according to both degradation in charging capability of the photosensitive drum 81 and degradation of toner, the amount of toner adhering to the photosensitive drum 81 can be made constant.
Further, by making the initial blade bias VB1(n=0, N=0) and the initial blade bias VB2(n=0, N=N1) different from each other, the amount of toner adhering to the developing roller 91 of the second toner cartridge can be brought close 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 photosensitive drum 81. As a result, the print density of the image forming apparatus 1 can be stabilized.
Further, the controller 100 changes the blade bias VBX(n, N) to be applied to the developing roller 91 according to an increase in the cumulative number of drum rotations “N” and to an increase in the cumulative dot count “n”, so that the developing bias can be changed according to both degradation of the photosensitive drum 81 and degradation of toner. This allows the amount of toner adhering to the photosensitive drum 81 to be made constant.
Further, by making the initial supply bias VK1(n=0, N=0) and the initial supply bias VK2(n=0, N=N1) different from each other, the amount of toner adhering to the developing roller 91 of the second toner cartridge can be brought close 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 photosensitive drum 81. As a result, the print density of the image forming apparatus 1 can be stabilized.
Further, the controller 100 changes the supply bias VKX(n,N) to be applied to the supply roller 92 according to an increase in the cumulative number of drum rotations and to an increase in the cumulative dot count, so that the supply bias can be changed according to both degradation of the photosensitive drum 81 and degradation of toner. This allows the amount of toner to be supplied to the photosensitive drum 81 to be made constant.
Further, by making the initial circumference velocity difference ΔV1(n=0, N=0) and the initial circumference velocity difference ΔV2(n=0, N=N1) different from each other, the amount of toner adhering to the photosensitive drum 81 when the second toner cartridge is used can be brought close to the amount of toner adhering to the photosensitive drum 81 when the first toner cartridge is used. This allows the amount of toner to be supplied from the developing roller 91 to the photosensitive drum 81 to be constant. As a result, the print density of the image forming apparatus 1 can be stabilized.
Further, the controller 100 changes the circumferential velocity difference ΔVX(n, N) between the developing roller 91 and the photosensitive drum 81 according to increases in the cumulative number of drum rotations and the cumulative dot count, so that the circumferential velocity difference can be changed according to both degradation of the photosensitive drum 81 and degradation of toner. This allows the amount of toner to be supplied to the photosensitive drum 81 to be made constant.
Next, a second embodiment of the present disclosure will be described in detail with reference to
As illustrated in
The image forming apparatus 1 of the second embodiment has the charging bias application circuit 210, a transfer current application circuit 270 and a cleaning bias application circuit 280. Similarly to the first embodiment, the controller 100 controls the charging bias application circuit 210 such that the value of the charging bias VT gradually increases as the cumulative number of drum rotations “N” of the photosensitive drum 81 increases as shown in
As illustrated in
Specifically, the controller 100 determines the value of the transfer current IX for an X-th toner cartridge 9 by adding a transfer current reference value I(n), which varies according to the cumulative dot count “n”, and a transfer current correction amount I(N), which varies according to the cumulative number of drum rotations (IX(n, N)=I(n)+I(N)), wherein X is an integer greater than zero (0).
As illustrated in
As described above, at the timing when the second toner cartridge 9 is newly attached to the drum cartridge 8, the cumulative number of drum rotations “N” is equal to N1, and the cumulative dot counts n is equal to zero (0). At this time, the controller 100 determines the initial transfer current I2(n=0, N=N1) for the second toner cartridge 9 based on the transfer current reference value I(n=0) and the transfer current correction amount I(N=N1). Specifically, the controller 100 determines the initial transfer current I2(n=0, N=N1) for the second toner cartridge 9 by calculating the formula of I(n=0)+I(N=N1). Thus, the initial transfer current I2(n=0, N=N1) of the second toner cartridge 9 differs from the initial transfer current I1(n=0, N=0) of the first toner cartridge 9. In the present embodiment, the initial transfer current I2(n=0, N=N1) for the second toner cartridge 9 is larger than the initial transfer current I1(n=0, N=0) for the first toner cartridge 9. That is, I2(n=0, N=N1)>I1(n=0, N=0).
Similarly, as the third, fourth, and fifth toner cartridges 9 are attached to the drum cartridge 8 in this order to perform image formation, the controller 100 executes processings of determining initial transfer currents I3(n=0, N=N2), I4(n=0, N=N3), and I5(n=0, N=N4) for the third, fourth and fifth toner cartridges 9 by calculating formulas: I(n=0)+I(N=N2), I(n=0)+I(N=N3), and I(n=0)+I(N=N4), respectively. The controller 100 determines the initial transfer current for the third, fourth and fifth toner cartridges 9 such that the initial transfer current increases according to the cumulative number of drum rotations “N”. That is, I5(n=0, N=N4)>I4(n=0, N=N3)>I3(n=0, N=N2)>I2(n0, N=N1).
As illustrated in
Referring back to
Specifically, the controller determines the value of the cleaning bias VCX for the X-th toner cartridge 9 by adding a cleaning bias reference value VC(n), which varies according to the cumulative dot count “n”, and a cleaning bias correction amount VC(N), which varies according to the cumulative number of drum rotations (VCX(n, N)=VC(n)+VC(N)) wherein X is an integer greater than zero (0).
As illustrated in
As described above, at the timing when the second toner cartridge 9 is newly attached to the drum cartridge 8, the cumulative number of drum rotations “N” is equal to N1, and the cumulative dot counts n is equal to zero (0). At this time, the controller 100 determines the initial cleaning bias VC2(n=0, N=N1) for the second toner cartridge 9 based on the cleaning bias reference value VC(n=0) and the cleaning bias correction amount VC(N=N1). Specifically, the controller 100 determines the initial cleaning bias VC2(n=0, N=N1) of the second toner cartridge 9 by calculating the formula of VC(n=0)+VC(N=N1). Thus, the initial cleaning bias VC2(n=0, N=N1) of the second toner cartridge 9 differs from the initial cleaning bias VC1(n=0, N=0) of the first toner cartridge 9 (see
Similarly, as the third, fourth, and fifth toner cartridges 9 are attached to the drum cartridge 8 in this order to perform image formation, the controller 100 executes processings of determining initial cleaning biases VC3(n=0, N=N2), VC4(n=0, N=N3), and VC5(n=0, N=N4) for the third, fourth and fifth toner cartridges 9 by calculating formulas: VC(n=0)+VC(N=N2), VC(n=0)+VC(N=N3), and VC(n=0)+VC(N=N4), respectively. The controller 100 determines the initial cleaning bias for the third, fourth and fifth toner cartridges 9 such that the absolute value of the initial cleaning bias increases according to the cumulative number of drum rotations “N”. That is, |VC5(n=0, N=N4)|>|VC4(n=0, N=N3)|>|VC3(n=0, N=N2)|>|VC2(n=0, N=N1)|.
As illustrated in
According to the above-described image forming apparatus 1 of the second embodiment, the following advantages are achieved.
After determining the initial transfer current I1(n=0, N=0) for the first toner cartridge 9, the controller 100 determines, based on the cumulative number of drum rotations “N”, the initial transfer current I2(n=0, N=N1) for the second toner cartridge 9 such that the initial transfer current I2(n=0, N=N1) is different from the initial transfer current I1(n=0, N=0) In this way, even when the photosensitive drum 81 degrades with an increase in the cumulative number of drum rotations “N”, the transfer amount of toner moved from the photosensitive drum 81 to a sheet S is made constant. Similarly, after determining the initial cleaning bias VC1(n=0, N=0) for the first toner cartridge 9, the controller 100 determines, based on the cumulative number of drum rotations “N”, the initial cleaning bias VC2(n=0, N=N1) for the second toner cartridge 9 such that the initial cleaning bias VC2(n=0, N=N1) is different from the initial cleaning bias VC1(n=0, N=0). In this way, even when the photosensitive drum 81 degrades with the increase in the cumulative number of drum rotations “N”, the amount of toner removed from the photosensitive drum 81 is made constant. This allows the print density of the image forming apparatus 1 to be stabilized while a plurality of toner cartridges are used in succession for one drum cartridge.
Further, the controller 100 changes the transfer current IX(n, N) to be applied to the transfer roller 82 according to an increase in the cumulative number of drum rotations “N” and to an increase in the cumulative dot count “n”, so that the transfer current IX(n, N) will be changed according to both degradation of the photosensitive drum 81 and degradation of toner. This allows the transfer amount of the toner moved from the photosensitive drum 81 to the sheet S is made constant. Similarly, the controller 100 changes the cleaning bias VCX(n, N) to be applied to the cleaning roller 84 according to the increase in the cumulative number of drum rotations and to the increase in the cumulative dot count, so that the cleaning bias VCX(n, N) will be changed according to both degradation of the photosensitive drum 81 and degradation of toner. This allows the cleaning amount of toner removed from the photosensitive drum 81 to be constant.
Further, the controller 100 gradually increases the transfer current IX(n, N) to be applied to the transfer roller 82 as the cumulative dot count “n” increases. In this way, even when the toner stored in the toner cartridge 9 degrades, the transfer amount of the toner moved from the photosensitive drum 81 to a sheet S is made constant. More specifically, even though charging performance of toner deteriorates as toner degrades, a resultant deterioration of the toner transfer is suppressed by increasing the transfer current IX(n, N). Similarly, the controller 100 gradually increases the absolute value of the cleaning bias VCX(n, N) as the cumulative dot count “n” increases. In this way, even when the toner stored in the toner cartridge 9 degrades, the cleaning amount of the toner is made constant. More specifically, even though charging performance of toner deteriorates as toner degrades, a resultant deterioration of the cleaning amount can be suppressed by increasing the absolute value of the cleaning bias VCX(n, N).
Further, the controller 100 gradually increases the transfer current IX(n, N) as the cumulative number of drum rotations “N” increases. In this way, even when the photosensitive drum 81 degrades, the transfer amount of the toner moved from the photosensitive drum 81 to a sheet S is made constant. More specifically, as the photosensitive drum 81 deteriorates, the surface of the photosensitive drum 81 becomes rough and the adhesion of toner increases. However, a resultant decrement of the toner transfer amount can be suppressed by increasing the transfer current IX(n, N). Similarly, the controller 100 gradually increases the cleaning bias VCX(n,N) as the cumulative number of drum rotations “N” increases. In this way, even when the photosensitive drum 81 degrades, the toner cleaning amount is made constant. More specifically, as the photosensitive drum 81 deteriorates, the surface of the photosensitive drum 81 becomes rough and the adhesion of toner increases. However, a resultant decrement of the toner cleaning amount can be suppressed by increasing the cleaning bias VCX(n,N).
It is noted that the drum cartridge has already deteriorated when the second and subsequent toner cartridges are installed. Accordingly, by making the initial transfer current I2(n=0, N=N1) larger than the initial transfer current I1(0, 0), the amount of toner transferring from the photosensitive drum 81 to a sheet S when the second toner cartridge is used can be brought close to the amount of toner transferring from the photosensitive drum to a sheet S when the first toner cartridge is used. This allows the print density of the image forming apparatus 1 to be stabilized while a plurality of toner cartridges are used in succession for one drum cartridge such that when toner runs out in one toner cartridge, the toner cartridge is replaced with the next toner cartridge. Similarly, by making the absolute value of the initial cleaning bias |VC2(n=0, N=N1) larger than |VC1(n=0, N=0), the cleaning amount of toner removed from the photosensitive drum 81 when the second toner cartridge is used can be brought close to the cleaning amount of toner removed from the photosensitive drum 81 when the first toner cartridge is used. This allows the print density of the image forming apparatus 1 to be stabilized while a plurality of toner cartridges are used in succession for one drum cartridge.
The present disclosure is not limited to the above-described embodiments and can be applied to various forms as exemplified below.
While the positively charged type toner is used in the first embodiment, negatively charged type toner may be used. In this case, the charging bias application circuit 210, developing bias application circuit 220, blade bias application circuit 230, and supply bias application circuit 240 may each be applied with negative bias voltage.
While the positively charged type toner is used in the second embodiment, negatively charged type tone may be used. In this case, the charging bias application circuit 210 and the cleaning bias application circuit may each be applied with negative bias voltage.
While the controller 100 reduces the absolute value |VGX(n, N)| of the developing bias VGX(n, N) as the cumulative dot count of the toner cartridge 9 increases in the first embodiment, the developing bias may be determined according to the cumulative number of drum rotations or the residual amount of toner stored in the toner cartridge 9, in place of the cumulative dot count. Similarly, the circumferential velocity difference ΔVX(n, N) between the photosensitive drum and the developing roller may be determined according to the cumulative number of drum rotations or the residual amount of toner stored in the toner cartridge 9, in place of the cumulative dot count.
While the circumferential velocity of the photosensitive drum 81 is constant in the first embodiment, the circumferential velocity of the photosensitive drum 81 may not necessarily be constant but may be changed. Further, while the circumferential velocity of the developing roller 91 is higher than the circumferential velocity of the photosensitive drum 81 in the first embodiment, the circumferential velocity of the developing roller 91 may be equal to or lower than the circumferential velocity of the photosensitive drum 81.
While the photosensitive drum 81 and developing roller 91 are driven by separate motors (i.e. the first motor 250 and the second motor 260) in the first embodiment, the photosensitive drum 81 and developing roller 91 may be driven by a single common motor. In this case, the developing roller and motor may be connected together through a transmission mechanism that is capable of changing a transmission ratio.
In the second embodiment, the drum cartridge 8 includes both of the transfer roller 82 and the cleaning roller 84. After determining both of the initial transfer current I1(n=0, N=0) and the initial cleaning bias VC1(n=0, N=0) for the first toner cartridge 9, the controller 100 determines for the second toner cartridge 9 the initial transfer current I2(n=0, N=N1) different from the initial transfer current I1(n=0, N=0) and the initial cleaning bias VC2(n=0, N=N1) different from the initial cleaning bias VC1(n=0, N=0) based on the cumulative number of the drum rotations N. However, the drum cartridge 8 may include at least one of the transfer roller 82 and the cleaning roller 84. If the drum cartridge 8 includes the transfer roller 82 but does not include the cleaning roller 84, after determining the initial transfer current I1(n=0, N=0), the controller 100 determines the initial transfer current I2(n=0, N=N1) different from the initial transfer current I1(n=0, N=0) based on the cumulative number of drum rotations “N. If the drum cartridge 8 includes the cleaning roller 84 but does not include the transfer roller 82, after determining the initial cleaning bias VC1(n=0, N=0), the controller 100 determines the initial cleaning bias VC2(n=0, N=N1) different from the initial cleaning bias VC1(n=0, N=0) based on the cumulative number of drum rotations “N”.
While the controller 100 increases the transfer current I as the cumulative dot count “n” of the toner cartridge 9 increases in the second embodiment, the current value may be determined according to the cumulative number of drum rotations “N” or according to the residual amount of toner stored in the toner cartridge 9, in place of the cumulative dot count “n”.
While the monochrome laser printer is exemplified as the image forming apparatus in each of the first and second embodiments, the image forming apparatus to be used in the present disclosure may be a color laser printer and, a copying machine, or a multifunction machine, or the like.
The components described in the first and second embodiments and modifications may arbitrarily be combined.
While the description has been made in detail with reference to the embodiments thereof, it would be apparent to those skilled in the art that many modifications and variations may be made therein without departing from the spirit of the disclosure.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2019-062588 | Mar 2019 | JP | national |
| 2019-062594 | Mar 2019 | JP | national |
This application is a continuation of U.S. patent application Ser. No. 16/828,198, filed Mar. 24, 2020, which claims priority from Japanese Patent Applications No. 2019-062588 filed Mar. 28, 2019 and No. 2019-062594 filed Mar. 28, 2019. The entire contents of the priority applications are incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | 16828198 | Mar 2020 | US |
| Child | 17152124 | US |
