JP2004062016A - Tandem full color image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tandem full color image forming apparatus by which the degree of freedom for the control of the potential of a photoreceptor surface at the time of image forming or the like is raised and also the need of complicated timing control for the application of potential to the photoreceptor surface is eliminated at the time of cleaning an electrifying means and a cleaning means. <P>SOLUTION: The tandem full color image forming apparatus is provided with several photoreceptors 1a-1d where photoreceptive layers 3a-3d are formed on respective supporting base bodies 2a-2d, the electrifying means 4a-4d provided at each photoreceptor, developing means 5a-5d, a power source for electrification bias 8 to supply each electrifying means with bias voltage and a power source for developing bias 9 to supply each developing means with bias voltage. Power sources for supporting base body bias 7a-7d to supply the supporting base bodies with bias voltage are respectively provided between the supporting base body and the grounding part of each photoreceptor, so that at least either the power source for the electrification bias 8 or the power source for the developing bias 9 is constituted as a common power source. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a tandem-type full-color image forming apparatus used for a color copying machine, a color printer, and the like.
[0002]
[Prior art]
The tandem type full-color image forming apparatus includes, for example, a photoconductor for forming an image for each color of yellow, magenta, cyan, and black.
[0003]
FIG. 11 is a cross-sectional view schematically showing a photoconductor of a conventional tandem-type full-color image forming apparatus and its periphery. In FIG. 11, reference numerals 101a to 101d denote photoconductors corresponding to yellow, magenta, cyan, and black from the left. Each of the photoconductors 101a to 101d is formed by coating a photosensitive layer 103a to 103d on a conductive support base 102a to 102d made of aluminum or the like, and the support bases 102a to 102d are grounded.
[0004]
Around the photoconductors 101a to 101d, charging members 105a to 105d such as charging rollers, developing members 106a to 106d such as developing rollers, and cleaning members 104a to 104d such as cleaning rollers are provided. A charging bias power supply 107a-107d for supplying a bias voltage to the charging members 105a-105d and a developing bias power supply 108a-108d for supplying a bias voltage to each of the developing members 106a-106d are provided for each of the photoconductors 101a-101d. Is provided. Further, a cleaning bias common power supply 109 for supplying a common bias voltage to each of the cleaning members 104a to 104d is provided.
[0005]
Then, at the time of image formation, a bias voltage is supplied from the charging bias power supplies 107a to 107d to the charging members 105a to 105d of the photoconductors 101a to 101d to charge the photoconductors 101a to 101d to a predetermined surface potential. The surfaces of the photoconductors 101a to 101d are exposed by an exposure unit (not shown) such as a laser or a light emitting diode according to the existence or non-existence of the image data to change the potential of the exposed portions. On the other hand, a bias voltage is supplied to the developing members 106a to 106d from the developing bias power sources 108a to 108d to develop the developer (toner), and thereafter, the toner image is transferred to the intermediate transfer belt 111 at a predetermined transfer position. .
[0006]
[Problems to be solved by the invention]
By the way, in the tandem type full-color image forming apparatus, it is necessary to change the relationship of the surface potential of the photoconductors 101a to 101d for image formation for each color. For example, the difference ΔV between the surface potential Vi after exposure and the potentials of the developing members 106a to 106d is set for each color according to environmental conditions and the like.
[0007]
However, in the conventional tandem-type full-color image forming apparatus shown in FIG. 11, the photoconductor surface potential at the time of image formation and the like is controlled by the charging bias power supplies 107a to 107d and the developing bias power supplies 108a to 108d. And the degree of freedom of control is small.
[0008]
In addition, when cleaning the charging members 105a to 105d and the cleaning members 104a to 104d, the timing of applying a potential to the surface of the photoconductors 101a to 101d is complicated in order to prevent carrier adhesion and toner scattering in the developing unit. I needed to control.
[0009]
The present invention has been made in order to solve such a drawback, and it is possible to increase the degree of freedom in controlling the surface potential of the photoconductor at the time of image formation and the like, and to clean the charging unit and the cleaning unit. It is another object of the present invention to provide a tandem-type full-color image forming apparatus that does not require complicated timing control of applying a potential to the surface of a photoconductor.
[0010]
[Problems to be solved by the invention]
The object is to provide a plurality of photoconductors each having a photosensitive layer formed on each support substrate, a plurality of charging units provided for each of the photoconductors and charging a photosensitive layer of the photoconductor, A plurality of developing means provided for each body, a charging bias power supply for supplying a bias voltage to the plurality of charging means, and a developing bias power supply for supplying a bias voltage to the plurality of developing means. In the tandem-type full-color image forming apparatus, a power supply for a support base bias for supplying a bias voltage to the support base is provided between a support base and a ground portion of each of the photoreceptors. At least one of the developing bias power supplies is configured as a common power supply that supplies a common bias voltage to each charging unit or each developing unit. It is solved by a tandem full-color image forming apparatus.
[0011]
In this tandem-type full-color image forming apparatus, a support base bias power supply for supplying a bias voltage to the support base is provided between the support base and the ground portion of each photoreceptor. Since a potential can be applied to the support base of the photoreceptor by the power supply, the surface potential and the like of the photosensitive layer after exposure can be controlled, and the degree of freedom of control increases accordingly.
[0012]
In addition, since the potential supply to the photoreceptor can be performed by the power supply for supporting substrate bias, the surface potential of the photoreceptor can be changed without complicated timing control, and the charging unit and the cleaning unit can be easily cleaned. become.
[0013]
Further, by providing the power supply for the bias of the support base between the support base of each photoconductor and the grounding portion, even if the charging potential and the developing potential are the same for each color, ΔV and other surface potentials for each color are different. Since the necessary conditions can be realized, at least one of the charging bias power supply and the developing bias power supply can be configured as a common power supply that supplies a common bias voltage to each charging unit or each developing unit. Therefore, the configuration of the charging bias power supply and / or the developing bias power supply is simplified as compared with the case where the charging bias power supply and the developing bias power supply are provided for each photoconductor. In particular, when both the charging bias power supply and the developing bias power supply are used as a common power supply for each color, one charging bias power supply is provided for a plurality of photoconductors, and the developing bias power supply is provided. Is reduced to one, which contributes to a reduction in the number of power supplies and a reduction in the number of components.
[0014]
In the tandem-type full-color image forming apparatus, a bias voltage supplied to each support substrate by the plurality of support substrate bias power sources may be variable. In this case, the variation of the surface potential setting of the photoconductor is further expanded.
[0015]
The tandem-type full-color image forming apparatus may have a configuration in which a cleaning unit is provided for each of the photoconductors, and a common power source for cleaning bias that supplies a common bias voltage to each cleaning unit. . In this case, the number of power supplies for the cleaning bias is small.
[0016]
A cleaning unit provided for each of the photoconductors; a cleaning bias power supply for supplying a bias voltage to each cleaning unit; a charging bias power supply; a developing bias power supply; a support base bias power supply; Control means capable of setting and controlling each bias voltage by a cleaning bias power supply, wherein the charging means or the cleaning means is in the form of a roller, and at a timing of removing an attached portion of the charging roller or the cleaning roller, the control means includes: The bias voltage of the support base bias power supply and the charging bias power supply is determined so that the potential of the charging unit is higher than the potential of the support base, or the potential of the cleaning unit is higher than the potential of the support base. The power supply for the support substrate bias and the It is good to determine the bias voltage of leaning bias power supply.
[0017]
In this case, it is possible to reliably remove adhered matter such as toner adhered to the charging roller or the cleaning roller.
[0018]
Further, the object is to provide a plurality of photoconductors each having a photosensitive layer formed on each support substrate, a plurality of charging means provided for each of the photoconductors, for charging a photosensitive layer of the photoconductor, A plurality of developing units provided for each photoconductor, a charging bias power supply for supplying a bias voltage to the plurality of charging units, and a developing bias power supply for supplying a bias voltage to the plurality of developing units; Wherein a common power supply for biasing the support substrate is provided between the support substrate of the photoreceptor and a ground portion, for supplying a common bias voltage to each support substrate. And a tandem type full-color image forming apparatus.
[0019]
In this tandem-type full-color image forming apparatus, a common power supply for supporting substrate bias for supplying a common bias voltage to each supporting substrate is provided between the supporting substrate of the photoreceptor and the grounding portion. Since a potential can be applied to the support base of the photoreceptor by the power supply, the surface potential and the like of the photosensitive layer after exposure can be controlled, and the degree of freedom of control increases.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a diagram schematically showing a photoconductor of a tandem-type full-color image forming apparatus according to an embodiment of the present invention and the periphery thereof.
[0021]
In FIG. 1, reference numerals 1a to 1d denote photoconductors corresponding to yellow (Y), magenta (M), cyan (C), and black (K) from the left. Each of the photoconductors 1a to 1d is formed by covering photosensitive drums 3a to 3d on conductive drum-shaped support bases 2a to 2d made of aluminum or the like.
[0022]
Around the photoconductors 1a to 1d, charging members 4a to 4d as charging units, developing members 5a to 5d as developing units, and cleaning members 6a to 6d as cleaning units are arranged, respectively. The charging members 4a to 4d include a charging roller and a scorotron charger, the developing members 5a to 5d include a developing roller, and the cleaning members 6a to 6d include a cleaning roller and a cleaning blade.
[0023]
Each of the charging members 4a to 4d is connected to one common power source 8 for charging bias. Each of the charging members 4a to 4d receives supply of a bias voltage from the common power source 8, and receives the photosensitive layers 3a to 3d. The surface is charged.
[0024]
Each of the developing members 5a to 5d is also connected to one common power source 9 for developing bias, and each of the developing members 5a to 5d receives a bias voltage from the common power source 9 at the time of image formation. Has become.
[0025]
Further, each of the cleaning members 6a to 6d is also connected to one common power source 10 for cleaning bias. At the time of cleaning, each of the cleaning members 6a to 6d receives supply of a bias voltage from this common power source 10. Has become.
[0026]
In each of the photoreceptors 1a to 1d, between the support bases 2a to 2d and the grounding section 12, support base bias power supplies 7a to 7d are interposed, respectively, and each of the support bases 2a to 2d A bias voltage can be supplied from the substrate bias power supplies 7a to 7d during image formation or cleaning.
[0027]
Each of the support base bias power supplies 7a to 7d is constituted by a voltage variable power supply capable of variably setting a bias voltage.
[0028]
In this embodiment, the voltage supply to each of the charging members 4a to 4d and the voltage supply to each of the developing members 5a to 5d are performed by a common charging bias common power supply 8 and a developing bias common power supply 9. However, only the voltage supply power supply to each of the charging members 4a to 4d may be made common, and a power supply may be individually provided for each of the developing members 5a to 5d, or vice versa. However, as shown in FIG. 1, the number of power supplies can be reduced by using both the charging bias power supply 8 and the developing bias power supply 9 as a common power supply. That is, in the conventional example shown in FIG. 11, the number of the power supplies for the charging bias and the power for the developing bias was eight in total. On the other hand, in the embodiment of FIG. 1, even if the increased number of the power sources 7 a to 7 d for the supporting substrate bias is added to the numbers of the common power source 8 for the charging bias and the common power source 9 for the developing bias, a total of six power sources are provided. Therefore, the number of power supplies can be reduced, and the number of parts can be reduced accordingly.
[0029]
Reference numeral 11 shown in FIG. 1 is a control unit. The control unit 11 controls the supply voltage of each of the charging bias power supply 8, the developing bias power supply 9, the cleaning bias power supply 10, and the support base bias power supplies 7a to 7d to the image forming mode or the cleaning mode. Control is performed according to various modes. In addition, the control unit 11 variably adjusts the supply voltage of each power supply according to environmental information such as temperature and humidity information input from a sensor or the like (not shown), image formation information such as image density information, durability information, and the like. It has been done.
[0030]
Reference numeral 13 shown in FIG. 1 denotes an intermediate transfer belt, and the toner images on the photoconductors 1a to 1d are transferred onto the intermediate transfer belt 13 and then onto a recording material (not shown).
[0031]
In the image forming apparatus shown in FIG. 1, a bias voltage is supplied from a charging bias power source 8 to the charging members 4a to 4d of the photoconductors 1a to 1d to form the photoconductors 1a to 1d at a predetermined surface potential. Charge. In this state, the surfaces of the photoconductors 1a to 1d are exposed by an exposure unit (not shown) such as a laser or a light emitting diode according to the existence or non-existence of the image data, and the potential of the exposed portions is changed to change the electrostatic latent image. Is formed.
[0032]
On the other hand, a bias voltage is supplied from the developing bias power supply 9 to the developing members 5a to 5d to develop with the developer, and then the developed image is transferred to the intermediate transfer belt 13 at a predetermined transfer position. The developer remaining on the photoconductors 1a to 1d that has not been transferred is collected by the cleaning members 6a to 6d.
[0033]
FIG. 2 shows three types of specific bias voltages to each member during image formation when no voltage is supplied to the cleaning members 6a to 6d, and the photoconductor surface potential Vi and ΔV after exposure at that time. It is.
[0034]
In FIG. 2A, a common power source 8 for charging bias supplies -600 V to the charging members 4a to 4d, a common power source 9 for developing bias supplies -450V to the developing members 5a to 5d, and -150 V, -100 V, -100 V, and -50 V were supplied to the respective support bases 2a to 2d by the power supplies 7a to 7d.
[0035]
The photoconductor surface potential Vi after exposure becomes -170 V, -120 V, -120 V, and -70 V, and ΔV becomes 280 V, 330 V, 330 V, and 380 V.
[0036]
Thus, by supplying a voltage to the support bases 2a to 2d, the ΔV of each color can be made variable. FIGS. 2 (2) and 3 (3) show examples of other bias voltages set based on environmental information and durability information. FIG. 2 (2) shows a case where the charge amount is set to a low absolute value on the negative side. FIG. 2 (3) shows a case where the charge amount is set to a high absolute value on the negative side.
[0037]
FIG. 3 shows a specific bias voltage applied to each member at the time of image formation when a bias voltage is supplied and a photoconductor surface potential Vi and ΔV after exposure at that time when a cleaning roller is used as the cleaning members 6a to 6d. , Three types.
[0038]
In FIG. 3A, a common power source 8 for charging bias supplies -600 V to the charging members 4a to 4d, and a common power source 9 for developing bias supplies -450V to the developing members 5a to 5d. The power supply 10 supplied 400 V to the cleaning rollers 6 a to 6 d, and the support base bias power supplies 7 a to 7 d supplied −150 V, −100 V, −100 V, and −50 V to each of the support bases 2 a to 2 d.
[0039]
The photoconductor surface potential Vi after exposure becomes -170 V, -120 V, -120 V, and -70 V, and ΔV becomes 280 V, 330 V, 330 V, and 380 V.
[0040]
By supplying a voltage to the support bases 2a to 2d in this manner, the ΔV of each color can be made variable. FIGS. 3 (2) and 3 (3) are examples of other bias voltages set based on environmental information and durability information, and FIG. 3 (2) shows a case where the charge amount is set to a low absolute value on the negative side. FIG. 3 (3) shows a case where the charge amount is set to a high absolute value on the negative side.
[0041]
FIG. 4 shows three types of specific bias voltages for each member when cleaning the charging roller when the charging members 4a to 4d are charging rollers and no voltage is supplied to the cleaning members 6a to 6d. is there.
[0042]
In FIG. 4A, GND is supplied from the common power source 8 for charging bias to the charging members 4a to 4d, -450 V is supplied from the common power source 9 for developing bias to the developing members 5a to 5d, and the power source for supporting base bias is supplied. -600 V was supplied to each of the support bases 2a to 2d by 7a to 7d. In this manner, the deposits on the charging rollers 4a to 4d can be collected on the photoconductors 1a to 1d, and can be collected from the photoconductor to a developing unit, a transfer unit, or a cleaning unit. FIGS. 4 (2) and 4 (3) show other examples of bias voltages set based on environmental information and durability information.
[0043]
FIG. 5 shows a specific bias voltage for each member when cleaning the charging roller and the cleaning roller when the charging members 4a to 4d are supplied to the charging roller and the cleaning members 6a to 6d are used as the cleaning roller to supply a voltage. The type is shown.
[0044]
In FIG. 5A, GND is supplied from the charging bias common power supply 8 to the charging rollers 4a to 4d, -450 V is supplied from the developing bias common power supply 9 to the developing members 5a to 5d, and the cleaning bias common power supply is supplied. 10, -800 V was supplied to the cleaning rollers 6a to 6d, and -600 V was supplied to each of the support bases 2a to 2d by the support base bias power supplies 7a to 7d. Therefore, the potential of each charging roller 4a-4d is set higher than the potential of each support base 2a-2d, and the potential of each cleaning roller 6a-6d is set lower than the potential of each support base 2a-2d.
[0045]
In this way, the deposits on the charging rollers 4a to 4d and the deposits on the cleaning rollers 6a to 6d are collected on the photoconductors 1a to 1d, and collected from the photoconductor to a developing unit, a transfer unit, a cleaning unit, or a charging unit. Then, it can be assumed that the image is cleaned at the time of image formation. By changing the timing of supplying a bias voltage to the charging members 4a to 4d, the cleaning members 6a to 6d, and the support bases 2a to 2d, cleaning can be performed before image formation (not shown). FIGS. 5 (2) and 5 (3) show other examples of bias voltages set based on environmental information and durability information.
[0046]
FIG. 6 shows another embodiment of the present invention. In this embodiment, the support base bias power supply for supplying a bias voltage to each of the support bases 2a to 2d is configured by one common power supply 15 having a variable voltage, and each of the support bases 2a to 2d is The grounding section 12 is grounded via a common power supply 15.
[0047]
On the other hand, the charging bias power supply and the developing bias power supply are not common power supplies, but one charging bias power supply 16a to each of the photosensitive members 1a to 1d and the developing members 5a to 5d. 16d, and developing bias power supplies 17a to 17d.
[0048]
Other configurations are the same as those of the embodiment shown in FIG.
[0049]
In the image forming apparatus shown in FIG. 6, a common bias voltage is supplied from the support base bias power supply 15 to each of the support bases 2a to 2d under the control of the control unit 11 during image formation, cleaning, and the like. A bias voltage is supplied from the charging bias power supplies 16a to 16d and the developing bias power supplies 17a to 17d to the charging members 4a to 4d and the developing members 5a to 5d.
[0050]
FIG. 7 shows a specific bias voltage to each member during image formation when no voltage is supplied to the cleaning members 6a to 6d in the image forming apparatus of FIG. 6, and a photoconductor surface potential Vi after exposure at that time. ΔV shows three types.
[0051]
In FIG. 7A, -480 V, -490 V, -490 V, and -500 V are supplied from the charging bias power supplies 16a to 16d to the charging members 4a to 4d, and the developing bias common power supplies 17a to 17d supply the charging members 4a to 4d. -360 V, -340 V, -340 V, and -430 V were supplied to the developing members 5a to 5d, and the support bases 2a to 2d were set to GND.
[0052]
The photoconductor surface potential Vi after exposure becomes −30 V, −50 V, −40 V, and −50 V, and ΔV becomes 330 V, 290 V, 300 V, and 380 V. Note that a voltage may be supplied from the support base bias power supply 15 to the support bases 2a to 2d without setting the support bases 2a to 2d to GND. 7 (2) and 7 (3) are examples of other bias voltages set based on environmental information and durability information. FIG. 7 (2) shows a case where the charge amount is set to a low absolute value on the negative side. FIG. 7 (3) shows a case where the charge amount is set to a high absolute value on the negative side.
[0053]
FIG. 8 shows a specific bias voltage applied to each member during image formation when a bias voltage is supplied using a cleaning roller as the cleaning members 6a to 6d, and the photoconductor surface potentials Vi and ΔV after exposure at that time. , Three types.
[0054]
In FIG. 8A, -480 V, -490 V, -490 V, and -500 V are supplied from the charging bias power supplies 16a to 16d to the charging members 4a to 4d, and the developing bias common power supplies 17a to 17d supply the charging members 4a to 4d. −360 V, −340 V, −340 V, and −430 V were supplied to the developing members 5 a to 5 d, and 400 V was supplied to the cleaning rollers 6 a to 6 d by the common power source 10 for cleaning bias, and the support bases 2 a to 2 d were set to GND.
[0055]
The photoconductor surface potential Vi after exposure becomes −30 V, −50 V, −40 V, and −50 V, and ΔV becomes 330 V, 290 V, 300 V, and 380 V. Note that a voltage may be supplied from the support base bias power supply 15 to the support bases 2a to 2d without setting the support bases 2a to 2d to GND. FIGS. 8 (2) and 8 (3) show examples of other bias voltages set based on environmental information and durability information. FIG. 8 (2) shows a case where the charge amount is set to a low absolute value on the negative side. FIG. 8 (3) shows a case where the charge amount is set to a high absolute value on the negative side.
[0056]
FIG. 9 shows three types of specific bias voltages for each member when cleaning the charging roller when the charging members 4a to 4d are charging rollers and no voltage is supplied to the cleaning members 6a to 6d. is there.
[0057]
In FIG. 9A, GND is supplied from the charging bias power sources 16a to 16d to the charging members 4a to 4d, and -380V and -450V are supplied from the developing bias power sources 17a to 17d to the developing members 5a to 5d. , −450 V, and −430 V, and −600 V to each of the support bases 2 a to 2 d by the common power supply 15 for support base bias.
[0058]
In this way, the deposits on the charging rollers 4a to 4d can be collected on the photoconductors 1a to 1d, and can be collected from the photoconductor to a developing unit, a transfer unit, or a cleaning unit. Since the developing bias power supplies 17a to 17d are not common, cleaning is performed by setting a fog margin for each color. However, a common fog margin may be used for each color. FIGS. 9B and 9C show other examples of bias voltages set based on environmental information and durability information.
[0059]
FIG. 10 shows a specific bias voltage to each member when cleaning the charging roller and the cleaning roller when the charging members 4a to 4d are supplied to the charging roller and the cleaning members 6a to 6d are used as the cleaning roller to supply a voltage. The type is shown.
[0060]
In FIG. 10A, GND is supplied from the charging bias power supplies 16a to 16d to the charging rollers 4a to 4d, and -380V and -450V are supplied from the developing bias power supplies 17a to 17d to the developing members 5a to 5d. , -450 V, -430 V, -800 V to the cleaning rollers 6a to 6d by the cleaning bias common power supply 10, and -600V to each of the support bases 2a to 2d by the support base bias common power supply 15. Therefore, the potential of each charging roller 4a-4d is set higher than the potential of each support base 2a-2d, and the potential of each cleaning roller 6a-6d is set lower than the potential of each support base 2a-2d.
[0061]
In this way, the deposits on the charging rollers 4a to 4d and the deposits on the cleaning rollers 6a to 6d are collected on the photoconductors 1a to 1d, and are collected from the photoconductor to a developing unit, a transfer unit, or a cleaning unit. It can be assumed that it has been cleaned at the time of image formation. By changing the timing of supplying a bias voltage to the charging members 4a to 4d, the cleaning members 6a to 6d, and the support bases 2a to 2d, cleaning can be performed before image formation (not shown). Since the developing bias power supplies 17a to 17d are not common, the fog margin is set for each color for cleaning, but the fog margin may be common for each color. FIGS. 10 (2) and 10 (3) show other examples of bias voltages set based on environmental information and durability information.
[0062]
The embodiments of the present invention have been described above, but the present invention is not limited to these embodiments. For example, in the embodiment, an image forming apparatus having a cleaner function using a cleaner member has been described, but a system without a cleaner member (cleanerless) may be used. Although the copying machine has been described, any tandem type full-color image forming apparatus such as a printer, a facsimile, or a multifunction peripheral of a copying machine, a printer, and a facsimile may be used. These may have a network connection function.
[0063]
Further, the supply voltage value in the embodiment is not limited to these examples. What is necessary is just to set arbitrarily according to various image forming apparatuses. Further, the bias voltage value may be changed in real time according to the number of prints, the operation time, or the like, which is the usage state of the apparatus.
[0064]
【The invention's effect】
According to the first aspect of the present invention, since a potential can be applied to the support substrate of each photoconductor by each power supply for biasing the support substrate, the surface potential of the photosensitive layer after exposure can be controlled, and the control can be made accordingly. The degree increases. In addition, since the potential supply to the photoreceptor can be performed by the power supply for supporting substrate bias, the surface potential of the photoreceptor can be changed without complicated timing control, and the charging unit and the cleaning unit can be easily cleaned. become. Further, at least one of the charging bias power supply and the developing bias power supply can be configured as a common power supply for supplying a common bias voltage to each charging unit or each developing unit. By using both the power supply for developing and the power supply for developing bias as a common power supply for each color, only one power supply for charging bias and one power supply for developing bias are required for a plurality of photoconductors. This can contribute to a reduction in the number of power supplies and a reduction in the number of parts.
[0065]
According to the second aspect of the invention, it is possible to further widen the variation of the surface potential setting of the photoconductor.
[0066]
According to the third aspect of the present invention, the number of power sources for the cleaning bias can be reduced.
[0067]
According to the fourth aspect of the present invention, it is possible to reliably remove adhered matter such as toner adhered to the charging roller or the cleaning roller.
[0068]
According to the invention according to claim 5, the surface potential of the photosensitive layer after exposure can be controlled, and the degree of freedom of control increases.
[Brief description of the drawings]
FIG. 1 is a schematic sectional view of a main part of an image forming apparatus according to an embodiment of the present invention.
FIG. 2 is a table showing an example of setting a bias voltage of each unit in the image forming apparatus shown in FIG. 1;
FIG. 3 is a table showing another example of setting a bias voltage.
FIG. 4 is a table showing another example of setting a bias voltage.
FIG. 5 is a table showing another example of setting a bias voltage.
FIG. 6 is a schematic sectional view of a main part of an image forming apparatus according to another embodiment of the present invention.
FIG. 7 is a table showing an example of setting a bias voltage of each unit in the image forming apparatus shown in FIG. 6;
FIG. 8 is a table showing another example of setting a bias voltage.
FIG. 9 is a table showing another example of setting a bias voltage.
FIG. 10 is a table showing another example of setting a bias voltage.
FIG. 11 is a schematic sectional view of a main part of a conventional image forming apparatus.
[Explanation of symbols]
1a-1d photoreceptor
2a to 2d Support base
3a-3d photosensitive layer
4a to 4d Charging member (charging means)
5a to 5d Developing member (developing means)
6a-6d Cleaning member (cleaning means)
7a-7d Power supply for supporting substrate bias
8 Common power supply for charging bias
9 Common power supply for developing bias
10 Common power supply for cleaning bias
11 control part (control means)
15 Common power supply for supporting substrate bias
16a to 16d Power supply for charging bias
17a-17d Power supply for developing bias

Claims (5)

A plurality of photoconductors each having a photosensitive layer formed on each support base, a plurality of charging means provided for each of the photoconductors, and a plurality of charging means for charging a photosensitive layer of the photoconductor, provided for each of the photoconductors; Tandem-type full-color printer comprising: a plurality of developing units; a charging bias power supply for supplying a bias voltage to the plurality of charging units; and a developing bias power supply for supplying a bias voltage to the plurality of developing units. In the image forming apparatus,
A support base bias power supply for supplying a bias voltage to the support base is provided between the support base and the ground portion of each photoconductor,
A tandem full-color image, wherein at least one of the charging bias power supply and the developing bias power supply is configured as a common power supply for supplying a common bias voltage to each charging unit or each developing unit. Forming equipment. 2. The tandem-type full-color image forming apparatus according to claim 1, wherein a bias voltage supplied to each support substrate by said plurality of support substrate bias power sources is variable. 3. The tandem-type full-color image forming apparatus according to claim 1, further comprising a cleaning unit for each of the photoconductors, and a cleaning bias common power supply for supplying a common bias voltage to each of the cleaning units. A cleaning unit provided for each photoconductor, a cleaning bias power supply for supplying a bias voltage to each cleaning unit, the charging bias power supply, the developing bias power supply, the support base bias power supply, and the cleaning bias Control means for setting and controlling each bias voltage by the power supply for
The charging unit or the cleaning unit has a roller shape, and at the timing of removing the attached portion of the charging roller or the cleaning roller, the control unit controls the supporting unit so that the potential of the charging unit becomes higher than the potential of the support base. The bias of the power supply for the support base and the bias of the power supply for the cleaning bias are determined such that the bias voltages of the power supply for the substrate bias and the power supply for the charging bias are determined, or the potential of the cleaning unit is lower than the potential of the support base. The tandem-type full-color image forming apparatus according to claim 1, wherein the voltage is determined. A plurality of photoconductors each having a photosensitive layer formed on each support base, a plurality of charging means provided for each of the photoconductors, and a plurality of charging means for charging a photosensitive layer of the photoconductor, provided for each of the photoconductors; Tandem-type full-color printer comprising: a plurality of developing units; a charging bias power supply for supplying a bias voltage to the plurality of charging units; and a developing bias power supply for supplying a bias voltage to the plurality of developing units. In the image forming apparatus,
A tandem-type full-color image forming apparatus, wherein a common power supply for biasing a support substrate is provided between the support substrate of the photoconductor and a grounding portion, for supplying a common bias voltage to each support substrate.

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