JP2002148888A - Printer and printing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a printer realizing the improved constitution of a power source and the improvement of print quality and preventing the deterioration of a photoreceptor. SOLUTION: By obtaining two-power source constitution consisting of a common power source to two colors including black and a common power source to other two colors, the load of the power source is reduced and the load of each power source device gets equal, so that the component parts of the power source device, for example, a transformer and an FET or the like are made low-ranked and respective circuits are made common, whereby the reduction of cost and miniaturization are realized. In a black-and-white mode, a developing device for only black is driven and the transfer devices and the electrifiers of respective image forming units for YMC are separated from the photoreceptor, so that the sleeve of a developing roll is not soiled, and the wear and the deterioration of the photoreceptor, the scattering of toner and the soiling of the paper are prevented, and then the improvement of the printing quality is realized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printing apparatus such as a printer and a copying machine, and a printing method. More specifically, the present invention relates to a printing apparatus and a printing method in which a high-voltage power supply applied to an image forming unit such as a printer or a copying machine having a color printing function is improved.

[0002]

2. Description of the Related Art Image forming apparatuses such as printers and copiers are
An electrostatic latent image is formed on a photosensitive drum by a contact charging device (hereinafter, charging device), a toner image is formed by a developing device, and a toner image is transferred to an intermediate transfer body by a primary contact transfer device (hereinafter, primary transfer device). I do. Further, after the image is transferred to the paper by the secondary transfer device, the paper is peeled from the intermediate transfer body by a peeling (detack) device, and an image is output.

In a color printing apparatus, a so-called image forming unit such as a photoconductor, a charging device, a developing device, and a transfer device is provided for each color of yellow (Y), magenta (M), cyan (C), and black (K). And color printing is performed by operating each of them.

[0004] Electrophotographic printers and copiers are
A high-voltage power supply for applying a specified voltage or current to a load around the photoconductor is provided. The voltage or current is
It is supplied for processing such as charging, development, transfer, peeling, and cleaning. In recent years, color printers and copiers have been improved in color and speed with the demand for high performance in the market. In order to meet the demand, a tandem type engine which prepares a photoreceptor and a block including charging, developing and transfer functions for each color (for example, YMCK color) and prints paper in one pass is becoming mainstream. An advantage of the tandem type is that since it is possible to print multiple colors (for example, four colors of YMCK) at a time, the same speed performance as a monochrome machine can be realized. Therefore, it is required to prepare a high-voltage power supply that responds to the load of the multicolor engine.

FIG. 17 is a diagram for explaining a conventional tandem power supply structure. FIG. 17 shows a high-voltage power supply (HVPS: High Voltage) for each image forming unit of YMCK.
tagePower Supply) and supplies power from a power supply dedicated to each unit.

The operation of the tandem-type printer shown in FIG. 17 will be briefly described. Around each photoconductor 1701, a charger 1702 having a charging roll is provided.
02, the photosensitive member 1701 is uniformly charged, and then is exposed by an exposure device (not shown), and the electrostatic latent image on the photosensitive drum is developed by a developing device 1703.
01 is transferred onto an intermediate transfer body by a primary transfer unit 1704. After these processes are successively performed for each of YMCK, they are transferred onto a sheet by a secondary transfer unit 1706, and the sheet is separated and output by a separation (detack) unit 1705.

In the above configuration, the charging device is in contact with the photosensitive drum, and a charging bias is applied by a charging power source to uniformly charge the photosensitive drum. Further, a developing roll constituting the developing device is disposed in proximity to the photosensitive drum, and rotates while supporting the charged toner on its surface,
The toner is transported to a developing position facing the photoconductor. Also,
A developing bias is applied to the developing roll from a developing power source. By the application of the developing bias, the toner carried on the surface of the developing roll flies toward the photosensitive drum, and a toner image is formed on the photosensitive drum.

The primary transfer device is arranged in contact with the photosensitive drum via the intermediate transfer member and rotates, and a primary transfer bias is applied by a primary transfer power supply to transfer a toner image to the intermediate transfer member. . These charging device power supplies,
The control circuit controls the bias application timing and the like of the developing device power supply and the primary transfer device power supply.

In the above-described charging and transfer processes, the power supply system based on the discharge of corotron wires and the like, which has conventionally been the mainstream, is directly supplied by a contact-type roll, and has a small gap due to advantages such as low power consumption and ozonelessness. At present, the minute discharge method has become mainstream. FIG. 18 shows a direct power supply configuration using a contact type roll (a), and a minute discharge method with a minute gap (b).
Is shown.

As described above, the image forming unit is required to supply a high-voltage power supply during its operation.
As shown in (1), when the image forming units of four colors of YMCK are provided, it is required to supply power to each of them.

Japanese Patent Application Laid-Open No. 5-33713 is one of prior arts which discloses a power supply configuration of a tandem engine. In this publication, an engine is provided for each color, and each has an independent power supply configuration. When the application timing is different for each color or the applied voltage is different for each color, it is effective to use an independent high-voltage power supply configuration. However, in this configuration, it is necessary to provide a power supply for each color, which leads to an increase in size and cost of the device.

In Japanese Patent Application Laid-Open No. 3-89264, an engine is provided for each color, and the same load (for example, a developing device for each color of YMCK) is used.
Power to each engine from a single high voltage power supply commonly connected to According to this configuration, a multi-color (for example, four-color) engine can be configured with a single high-voltage power supply, and can be downsized.
It can contribute to cost reduction.

However, even in a full-color machine having a color printing function, many users overwhelmingly execute a single-color mode (for example, black-and-white printing and black-and-white copying) as compared with color printing. There are many at present. Under such circumstances, there is a demand for a configuration in which power is supplied only to necessary units without supplying unnecessary power to each image forming unit of the printer. When a voltage is applied to all the image forming units even during single-color printing (copying), the life of the photosensitive member or the like is shortened and wasteful power is consumed.

When an engine of another color is operated in the black-and-white mode, the application of a potential to the photoreceptor causes abrasion of the photoreceptor layer due to a bias. Wear of the photoreceptor when it is not used for printing is a serious problem from the viewpoint of life and run costs of consumables. Even when the wear of the photoreceptor is small and there is no problem, if the developing device is driven for a long time while maintaining the cleaning potential, the phenomenon that the toner is developed on the developing roll (sleeve contamination) occurs. If the toner adheres to the sleeve, the toner adhered to the developing roll is developed at the next printing, so that there is a problem that the print density increases until the toner adhered to the developing sleeve is consumed. In addition, fog of another color is generated by applying a potential to the primary transfer device.

According to Japanese Patent Application Laid-Open No. 9-109512, when a full-color machine has an engine for each color, a total of two high-voltage power supplies of K color independent and common to Y, M, and C colors are used to reduce the size and cost. Has been realized. This configuration is designed for single-color printing (copying). In the single-color mode (for example, black-and-white printing and black-and-white copying), the output is applied only to the engine to be used. No power consumption.

[0016]

As described above, providing a power supply means for each color in a color printing machine leads to an increase in cost and an increase in the size of the apparatus, which is a problem. Further, if one high-voltage power supply is used for a common power supply configuration, for example, an engine of four colors or three colors, the power supply needs to have a large capacity configuration, and the cost of one power supply unit increases. If a voltage is applied to another color in the black and white mode in the common power supply configuration, the above-described problems such as deterioration of the photoconductor occur.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and has realized a reduction in the size of a color printing device such as a printer or a copying device, a reduction in the cost of a power supply device, and a reduction in the photoreceptor deterioration in a monochrome mode. It is an object of the present invention to provide a printing apparatus and a printing method capable of preventing the printing and improving the printing quality.

[0018]

According to a first aspect of the present invention, there is provided:
In a printing apparatus having an image forming mechanism for printing at least four colors including black and performing printing in a black-and-white printing mode and a color printing mode, a load on the image forming mechanism corresponding to black and another first color is reduced. A first power supply device for supplying power commonly to the first and second power supply devices, and a power supply device for supplying power commonly to the loads of the image forming mechanism corresponding to the second color and the third color other than the black and the first color. And a control unit for prohibiting the operation of the load of the image forming mechanism corresponding to the first color during the monochrome print mode operation, wherein the control unit is in the monochrome print mode or in the color print mode. The printing apparatus executes a process of prohibiting or canceling the operation of the load according to whether the mode is a mode. With this configuration, the load on each power supply unit is reduced and equalized, so that the ranks and commonality of parts can be reduced, and costs can be reduced, and operation around the photoreceptor in the non-printing state is prohibited. As a result, print quality deterioration due to deterioration of the photoreceptor is prevented.

Further, in one embodiment of the printing apparatus of the present invention, the load of the image forming mechanism corresponding to the first color includes a developing roll, and a developing device that rotates the developing roll with respect to the photosensitive member to perform development. Wherein the operation of the load is at least rotation of a developing roll of the developing device, and wherein the control means executes control for inhibiting rotation of the developing roll of the developing device in a black-and-white printing mode. I do. According to this configuration, since the rotation of the developing device around the photoconductor in the non-printing state is prohibited, the print quality is prevented from deteriorating due to sleeve contamination.

Further, in one embodiment of the printing apparatus according to the present invention, the load of the image forming mechanism corresponding to the first color is a transfer device, and the transfer device is separated from the photosensitive member by a distance from a transfer position. A retract mechanism that moves the transfer device to the retracted position, wherein the operation of the load is transfer to the photoconductor of the transfer device, and the control unit moves the transfer device from the transfer position to the retract position during the black-and-white printing mode. It is characterized in that the retractor mechanism is controlled so as to execute a moving retract. According to this configuration, the contact of the transfer unit in the non-printing state is prohibited, so that the print quality is prevented from deteriorating due to fog. The same effect can be achieved by the transfer device in both the primary transfer in the intermediate transfer system and the transfer device in the transfer belt system.

Further, in one embodiment of the printing apparatus of the present invention, a load of the image forming mechanism corresponding to the first color is a charger, and the charger is spaced apart from a photosensitive member from a charging position. A retract mechanism for moving the charger to the retracted position, wherein the operation of the load is charging of the photoreceptor of the charger, and the control unit moves the charger from the charging position to the retract position in the black-and-white printing mode. It is characterized in that the retractor mechanism is controlled so as to execute a moving retract. According to this configuration, the contact with the charger in the non-printing state is prohibited, so that deterioration of the print quality due to deterioration of the photoconductor is prevented.

Further, in an embodiment of the printing apparatus according to the present invention, the image forming mechanism is a tandem system of four or more stations having image forming means for each color. According to this configuration, high-speed printing can be performed by a series of printing mechanisms.

Further, a second aspect of the present invention is a printing method for performing printing in a black-and-white printing mode and a color printing mode while having separate image forming units of at least four colors including black, and A first power supply device common to the first color image forming unit;
A second power supply common to the image forming units for the black and the other colors other than the first color is separately provided, and in the black-and-white printing mode, the first power supply is turned on; A printing method characterized by performing switching control of turning off a second power supply and turning on both the first power supply and the second power supply in a color printing mode. With this configuration, the load on each power supply device is reduced and equalized, so that the ranks of the components can be reduced, the circuits can be shared, the cost can be reduced, and the power saving in the monochrome mode can be realized. You.

Further, in one embodiment of the printing method of the present invention, the printing method includes a control step of prohibiting an operation of a load in at least the first color image forming unit excluding black. According to another feature of the present invention, the operation of the load is prohibited or the prohibition cancellation is performed depending on whether the mode is the monochrome print mode or the color print mode. According to this configuration, since the operation around the photoconductor in the non-printing state is prohibited, print quality deterioration due to deterioration of the photoconductor is prevented.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of a printing apparatus and a printing method according to the present invention will be described below with reference to the drawings.

[0026]

FIG. 1 shows the configuration of a printing apparatus according to an embodiment of the present invention. As shown in FIG. 1, the printing apparatus described in the present embodiment has Y (yellow), M (magenta), C (cyan), and K (black) image forming units. As shown in the image forming unit of Y (yellow) in FIG.
1, a charging device 102, a developing device 103, and a primary transfer device 104. Other M (magenta), C (cyan), and K (black) image forming units have the same photoconductor, charger,
It has a developing device and a transfer device.

A high voltage power supply (HVPS: High Voltage Power Supply) as a power supply means for the photoreceptor, charging device, developing device and transfer device of each image forming unit is a common power supply 211 for C (cyan) and K (black). , 21
2, 213, and common power supplies 311, 312, and 313 for Y (yellow) and M (magenta).

For example, during color printing, Y (yellow), M (magenta), C (cyan), K (black)
In each of the image forming units, the charger 102 is the photosensitive member 1
01, a charging bias is applied by the charging power sources 212 and 312, and the photoconductor 101 is uniformly charged. A developing device 103 that is exposed by an exposing device (not shown) and constitutes a developing device is disposed in proximity to the photoconductor 101, carries charged toner on its surface, and rotates.
The toner is conveyed to a developing position facing the photoconductor 101.
The developing devices 193 include developing power supplies 213 and 313.
, A developing bias is applied. Due to the application of the developing bias, the toner carried on the surface of the developing device 103 flies toward the photoconductor 101, and a toner image is formed on the photoconductor 101.

The primary transfer device 104 is arranged in contact with the photosensitive member 101 via the intermediate transfer member and rotates, and a primary transfer bias is applied by the primary transfer power sources 211 and 311, and the primary transfer device 104 and the primary transfer device are connected to the primary transfer device. Transfer units 211 and 31
1 to transfer the toner image onto the intermediate transfer member. These charger power supplies 212 and 312, developer power supplies 213 and 3
13 and the primary transfer unit power supplies 213 and 313 are controlled by a control circuit (not shown) such as the timing of bias application.

FIG. 2 shows a circuit configuration example of the power supply device. The embodiment described below is described as a power supply device in a developing device, but is also applicable to a charging device and a primary transfer device. As shown in FIG. 2, the power supply device of the present invention comprises:
A common power supply for C (cyan) and K (black), and Y
(Yellow), common power supply for M (magenta)
Voltage and current are supplied to each image forming unit by one power supply. Common power supply (HVPS) 213
Is a common AC power supply AC-CK for each of C (cyan) and K (black) units, and a separation capacitor 25.
1, independent DC power supplies DC-C, DC-K for each of the C (cyan) and K (black) units.
Having. A common power supply (HVPS) 313 is a common AC power supply AC-CK for each of the Y (yellow) and M (magenta) units, and a Y (yellow) and M (magenta) connected via a separation capacitor 251. Each unit has an independent DC power supply DC-Y, DC-M.

In the case of the full-color mode, all the circuits of the common power supply (HVPS) 213 and the common power supply (HVPS) 313 in FIG. 2 operate, and power is supplied to YMCK and all the image forming units. In the case of the monochrome mode, the AC-C of the common power supply (HVPS) 213 in FIG.
Only K and DC-K operate.

According to this configuration, a common power supply for two colors K (black) and C (cyan), and M (magenta) and Y
(Yellow), the load is reduced and the load of each power supply device is equalized as compared with the conventional common power supply for three or four colors. It is possible to reduce the rank of the components of the device, such as transformers and FETs, and to make each circuit common, eliminating the need for large capacity specifications, reducing the number of heat sinks required for large capacity specifications, reducing costs and miniaturizing. Is realized. In the above example, K (black) and C (cyan) 2
Although a common power supply is provided as one set of colors, a common power supply is provided for a set of K (black) and M (magenta) or K (black) and Y (yellow), and the other two power supplies are provided. A configuration in which another common power supply is provided for the color may be adopted.

[Developer motor configuration] In the printing apparatus of the present invention, not only the power supply from the above-described power supply to each image forming unit is switched between the full color mode and the monochrome mode, but also The rotation and stop control of the developing device of each image forming unit is executed according to the mode.

FIG. 3 is a diagram for explaining a motor control configuration of a developing unit of each image forming unit in the printing apparatus of the present invention. Developing units 301K, 301C,
Each of 301M, 301Y has a separate motor 302K, 302C, 302M, 302Y as a respective drive reducer.

In the case of the full color mode, the motor 302
K, 302C, 302M, and 302Y all operate (ac
live), and the developing device 301 of each image forming unit.
K, 301C, 301M, and 301Y all drive (rotate).

On the other hand, in the case of the monochrome mode, the motor 302
Only K is driven and motors 302C, 302M, 302Y
Are stopped (non-active), and only the developing device 301K of the black (K) image forming unit rotates.

FIG. 4 is a diagram showing the operation states of the rotation of the photosensitive drum, the rotation of the developing unit, and the output of the high-voltage power supply to the developing unit in the full-color mode and the black-and-white mode in each image forming unit. FIG. 4A shows the rotation of the photosensitive drum of each image forming unit, the rotation of the developing unit, and the change of the output of the high voltage power supply to the developing unit in the full color mode, and FIG. 4B shows the image forming unit in the monochrome mode. 3 shows changes in the rotation of the photosensitive drum, the rotation of the developing device, and the output of the high-voltage power supply to the developing device.

(A) In the full-color mode, FIG.
Are operated, and power is supplied to all the image forming units YMCK. FIG.
All the motors of the developing device are also driven, and all the developing devices are rotated.

On the other hand, in FIG.
Only the power supply 213 provided in common to K (black) and C (cyan) supplies power to each of the KC developing units, while the power supply 213 is common to M (magenta) and Y (yellow). The installed power supply 313 is stopped, and the power supply to each of the MY developing units is stopped. Further, only the motor 302K shown in FIG.
C, 302M and 302Y all stop (non-act
ive), and only the developing device 301K of the black (K) image forming unit rotates. FIG. 4B shows this state.

FIG. 5 shows a control configuration for executing control of the power supply and the developing device motor according to the present embodiment. A control unit (MCU: machine control unit) 501 is based on a mode switching signal based on a user's input setting or an automatic setting such as original reading, and is M (magenta) or Y (yellow) according to a full color mode or a monochrome mode. High-voltage power supply of the developing device commonly installed with respect to YM502, K
(Black) and C (cyan), a high-voltage power supply-CK 503 of a developing unit commonly installed, and a developing unit K for driving the K (black) developing unit: a motor 504
And the developing device YMC for driving the developing devices of M (magenta), Y (yellow) and C (cyan): control of the motor 505.

In the full-color mode, an operation signal (ON) is output from the MCU 501 to the high-voltage power supply YM502 of the developing device and the high-voltage power supply CK503 of the developing device, and the high-voltage output is output to the image forming unit Y506 and the image forming unit M5.
07, image forming unit C508, image forming unit K
509. Developing device K: motor 504,
Developing unit YMC: An operation signal (ON) is also output from the MCU 501 to the motor 505, and the developing units of all units rotate.

On the other hand, in the monochrome mode, a stop signal (OF) is sent from the MCU 501 to the high voltage power supply-YM502 of the developing device.
F) is output, an operation signal (ON) is output only to the high-voltage power supply-CK503 of the developing device, and a high-voltage output is supplied only to the image forming units C508 and K509. The developing device K: the motor 504 includes an MCU.
Although an operation signal (ON) is output from the developing device 501, the developing device Y
MC: A stop signal (OFF) is output from the MCU 501 to the motor 505, so that only the developing device K rotates and the developing device YMC stops.

FIG. 6 shows a processing flow of this configuration. First,
The MCU determines whether the mode is the full color mode (S10).
1) If the mode is the full color mode, step S1
In 02, the developing motor YMC is turned on and the developing motor K is turned on. Further, step S1
At 03, the high voltage power supply YM and the high voltage power supply CK are turned on. On the other hand, if it is determined in step S101 that the mode is not the full color mode, that is, the mode is the monochrome mode,
In step S104, only the developing motor K is turned ON. Further, in step S105, the high voltage power supply CK
Only ON is set. Print these processes (S1)
The process is repeatedly executed until No in step 06).

According to this configuration, a common power supply for two colors K (black) and C (cyan), and M (magenta) and Y
(Yellow), the load is reduced and the load of each power supply device is equalized as compared with the conventional common power supply for three or four colors. It is possible to reduce the rank of components such as transformers and FETs, and to make each circuit common, eliminating the need for large-capacity specifications. Is realized.

Further, in the black and white mode, the developing device motor of only K (black) is driven, and C (cyan), M
Since the (magenta) and Y (yellow) developing unit motors are configured to be stopped, contamination of the sleeve of the developing roll is prevented.

Note that, in the configuration shown in FIG.
Although the individual motors are independently arranged for the developing units of each of the K image forming units, as shown in FIG. 7, an independent motor 70 is provided for the K (black) developing units.
1 and a common motor 702 for the developing units of the three image forming units C (cyan), M (magenta), and Y (yellow). , 702, and in the monochrome mode, only the motor 701 may be driven.

As shown in FIG. 8, K (black), C (cyan), M (magenta), Y (yellow)
Motor 8 common to the developing units of the respective image forming units.
The same effects as described above can also be obtained by providing a clutch 802 that transmits or stops the drive to the C (cyan), M (magenta), and Y (yellow) developing units in accordance with the mode switching by installing 01. It is possible.

FIG. 9 shows a control configuration for executing the control of the power supply and the developing device motor of the embodiment using the clutch. Control means (MCU: machine control unit) 901
Are M (magenta), Y (magenta) according to the full-color mode and the black-and-white mode based on a mode switching signal based on user input settings or automatic settings such as document reading.
(Yellow), a high-voltage power supply of a developing device commonly provided for YM902, K (black), and C (cyan). (Black), M (magenta), Y (yellow), and C (cyan) developing device motors 904 for driving the developing devices, and M (magenta), Y (yellow), and C (cyan) developing drive transmission to the developing devices The control of the developing device clutch 905 for switching the stop is executed.

In the full-color mode, an operation signal (ON) is output from the MCU 901 to the high-voltage power supply YM902 of the developing unit and the high-voltage power supply CK903 of the developing unit, and the high-voltage output is output to the image forming unit Y906 and the image forming unit M9.
07, image forming unit C908, image forming unit K
909. Also, an operation signal (ON) is output from the MCU 901 to the developing device motor 904 and the developing device clutch 905, and the developing devices of all units rotate.

On the other hand, in the monochrome mode, a stop signal (OF) is sent from the MCU 901 to the high voltage power supply-YM 902 of the developing device.
F) is output, an operation signal (ON) is output only to the high voltage power supply-CK903 of the developing device, and a high voltage output is supplied only to the image forming units C908 and K909. Further, the MCU 50 is connected to the developing device motor 904.
1 outputs an operation signal (ON), but the MCU 501 sends a stop signal (OF) to the developing device clutch 905.
F) is output, and the driving force of the motor is changed to the image forming unit Y.
Only the developing device K rotates without transmitting to the MC, and the developing device YM
C stops.

FIG. 10 shows a processing flow of this configuration. First, the MCU determines whether or not the mode is the full color mode (S
201) If the mode is the full color mode, in step S202, the developing motor is turned ON,
Turn on the developing clutch. Further, step S203
, The high voltage power supply YM and the high voltage power supply CK are turned on. On the other hand, if it is determined in step S201 that the mode is not the full color mode, that is, the mode is the black and white mode, in step S204, only the developing motor is turned ON, and
Turn off the developing clutch. Further, step S20
At 5, only the high voltage power supply CK is turned on. These processes are repeatedly executed until the printing is completed (No in S206).

As described above, by using the clutch mechanism, it becomes possible to use only one developing device motor, and in addition to the above-described effects, downsizing and labor saving of the device can be realized.

[Retract Configuration] Next, a description will be given of a retract configuration executed in the printing apparatus of the present invention in accordance with switching between the full color mode and the monochrome mode.

As described with reference to FIG. 1, Y (yellow), M (magenta), C (cyan), K (black)
In each of the image forming units, the charger 102 is the photosensitive member 1
01, a charging bias is applied by the charging power sources 212 and 312, and the photoconductor 101 is uniformly charged. A developing device 103 that is exposed by an exposing device (not shown) and constitutes a developing device is disposed in proximity to the photoconductor 101, carries charged toner on its surface, and rotates.
The toner is conveyed to a developing position facing the photoconductor 101.
The developing devices 193 include developing power supplies 213 and 313.
, A developing bias is applied. Due to the application of the developing bias, the toner carried on the surface of the developing device 103 flies toward the photoconductor 101, and a toner image is formed on the photoconductor 101.

Further, the primary transfer unit 104 is arranged in contact with the photosensitive member 101 via the intermediate transfer member and rotates, and a primary transfer bias is applied by the primary transfer power sources 211 and 311, and the primary transfer device 104 and the primary transfer device are connected to each other. Transfer units 211 and 31
1 to transfer the toner image onto the intermediate transfer member.

In the case of the full color mode, the processing of each color is executed in each image forming unit, and there is no problem.
In the black-and-white mode, in each of the YMC image forming units, the charging device, the transfer device, and the like contacting the photoconductor with the rotation of the photoconductor while applying the high-voltage power or stopping the application of the high-voltage power. Will rotate in contact with each other. The rotation of the charging device and the transfer device in a state in which the charging device and the transfer device are in contact with the photoconductor while applying a high-voltage power supply causes a problem such as deterioration of the photoconductor and fog.

As a configuration for solving these problems, a retraction configuration for separating the charger and the transfer unit of each YMC image forming unit from the photoconductor in the black and white mode is shown in FIG. Has a photoreceptor 1101, a charger 1102, a developing unit 1103, and a transfer unit 1104.

In the full color mode, in each of the YMCK image forming units, the charger 1102 and the developing device 1
103, the primary transfer device 1104 comes into contact with the photoconductor 1101, and executes respective processes.

In the printing apparatus of the present invention, in the black-and-white mode, the charger 1102YMC and the primary transfer unit 1104YM of each of the YMC image forming units that do not execute the printing process.
A process for separating C from the photoconductor 1101YMC is executed.

FIG. 12 shows the power supply and the power supply (B
(CR: contact charger) shows a control configuration for executing control. Control means (MCU: machine control unit) 120
Reference numeral 1 denotes M (magenta), Y according to a full-color mode or a black-and-white mode based on a mode switching signal based on a user input setting or an automatic setting such as original reading.
(Yellow) high voltage power supply-YM
1202, a high-voltage power supply-CK1203 commonly installed for K (black) and C (cyan) is controlled.
The control of the cam which is a retract mechanism individually set for (black), C (cyan), M (magenta), and Y (yellow) is executed.

FIG. 13 shows an example of a cam structure as a retract mechanism. FIG. 13A shows a state in which the charger 1302 keeps the contact state with the photoconductor 1301 and shows a chargeable state during the printing process. When the mode is switched here, the cam 1303 rotates and the support member 1304
The spring 1305 fixed to the
The charger 1302 connected to the photoconductor 1301 moves relative to the photoconductor 1301, and operates to separate the charger 1302 from the photoconductor 1301 as shown in FIG. The MCU of FIG. 12 outputs such a signal for controlling the cam rotation according to the mode switching. Note that the retract configuration in FIG. 13 is an example, and another mechanism, such as a plunger mechanism, may be employed.

Returning to FIG. 12, power supply and retract control will be described. In the full-color mode, the high-voltage power supply of the charger-YM1202 and the high-voltage power supply of the charger-CK120
3, an operation signal (ON) is output from the MCU 1201, and the high voltage output is output from the image forming unit Y 1208, the image forming unit M 1209, the image forming unit C 1210,
The image is supplied to the image forming unit K1211. Also, YM
CK All the chargers (B
CR) MCU 120 also for cams 1204 to 1207
1 outputs a contact maintaining signal (Down), and the chargers of all the units come into contact with the photoconductors.

On the other hand, in the black-and-white mode, a stop signal (OFF) is output from the MCU 1201 to the high voltage power supply YM1202 of the charger, and the high voltage power supply CK120 of the charger is output.
3, the operation signal (ON) is output, and only the image forming unit C1210 and the image forming unit K1211 are supplied with the high voltage output. Also, a charger (BCR) -K corresponding to the image forming unit 1211 of K (black).
A contact maintaining signal (Down) is output from the MCU 1201 only to the cam 1204, and a charger (BCR) -YMC cam 1205-1 corresponding to the YMC unit is also provided.
For 207, a contact release signal (U
p) is output. As a result, in the black and white mode,
The charger of only K (black) comes into contact with the photoconductor, and the chargers of the other units are separated from the photoconductor.

FIG. 14 shows a processing flow of this configuration. First, the MCU determines whether or not the mode is the full color mode (S
If the mode is the full-color mode, in step S302, each YMCK cam of the contact charger (BCR) is brought into contact with Down, that is, the photoconductor. Further, in step S303, the high-voltage power supply YM and the high-voltage power supply CK are turned on. On the other hand, if it is determined in step S301 that the mode is not the full color mode, that is, the mode is the monochrome mode, in step S304, only the K (black) cam of the contact charger (BCR) is set to Down,
That is, the photosensitive member is brought into contact with the photosensitive member. Further, step S30
At 5, only the high voltage power supply CK is turned on. These processes are repeatedly executed until the printing is completed (No in S306).

On the other hand, FIG. 1 shows a control configuration for controlling a transfer unit (BTR: bias transfer roll) and executing power supply control.
It is shown in FIG. A control unit (MCU: machine control unit) 1501 is provided with M (magenta) and Y (yellow) according to a full-color mode or a black-and-white mode based on a mode switching signal based on a user's input setting or automatic setting such as document reading. High-voltage power supply commonly installed for YM1502, K (black), C (cyan)
Control the high voltage power supply-CK1503 installed in common to
Further, the control of the cam which is a retract mechanism individually set for K (black), C (cyan), M (magenta), and Y (yellow) is executed.

In the full color mode, the high voltage power supply of the primary transfer device-YM1502 and the high voltage power supply of the primary transfer device-CK15
An operation signal (ON) is output from the MCU 1501 to the image forming unit 03, and the high voltage output is output from the image forming unit Y1508, the image forming unit M1509, and the image forming unit C151.
0, supplied to the image forming unit K1511. Also,
All transfer units (B
TR) MCU 150 is also used for cams 1504-1507.
1 outputs a contact maintaining signal (Down), and the primary transfer units of all units come into contact with the photoreceptor via the intermediate transfer member.

On the other hand, in the monochrome mode, a stop signal (OFF) is output from the MCU 1501 to the high voltage power supply -YM1502 of the primary transfer device, and the high voltage power supply -CK of the primary transfer device is output.
An operation signal (ON) is output only to the image forming unit 1503, and the image forming unit C1510 and the image forming unit K151 are output.
Only one is supplied with high voltage output. Also, K (black)
Primary transfer unit (B) corresponding to the image forming unit 1511
TR) -K cam 1504 outputs a contact maintaining signal (Down) from MCU 1501 only to Y cam
The MCU 1501 outputs a contact release signal (Up) to the primary transfer unit (BTR) -YMC cams 1505 to 1507 corresponding to the C unit. As a result, in the black-and-white mode, the primary transfer unit (BT) having only K (black) is used.
R) comes into contact with the photosensitive member via the intermediate transfer member, and the primary transfer unit (BTR) of the other units is separated from the photosensitive member.

FIG. 16 shows a processing flow of this configuration. First, the MCU determines whether or not the mode is the full color mode (S
401) If the mode is the full-color mode, in step S402, the YMCK cams of the primary transfer unit (BTR) are brought into contact with the photoconductor via the Down, that is, the intermediate transfer body. Further, in step S403, the high-voltage power supply YM and the high-voltage power supply CK are turned on. On the other hand, if it is determined in step S401 that the mode is not the full-color mode, that is, the mode is the black-and-white mode, in step S404, only the K (black) cam of the primary transfer unit (BTR) is set to Down, that is, the photoconductor via the intermediate transfer member. Make contact. Further, only the high voltage power supply CK is turned on in step S405. These processes are repeatedly executed until the printing is completed (No in S406).

In the above-described example, the retraction control of the transfer device and the charging device has been described as an individual control configuration with reference to FIGS. 12 and 15, but may be executed as one control configuration. Further, in the above-described embodiment, the transfer device is described as the primary transfer device in the configuration employing the intermediate transfer method. However, the transfer device of the transfer belt type not using the intermediate transfer method may be used. Achieved.

As described above, according to this configuration, in the black-and-white mode, the transfer device and the charger of each YMC image forming unit are separated from the photosensitive member.
The application of high-voltage power to the transfer device in contact with the photoconductor is prevented, and deterioration of the photoconductor, fogging, and the like can be prevented.

The present invention has been described in detail with reference to the specific embodiments. However, it is obvious that those skilled in the art can modify or substitute the embodiment without departing from the spirit of the present invention. That is, the present invention has been disclosed by way of example, and should not be construed as limiting. In order to determine the gist of the present invention, the claims described at the beginning should be considered.

[0072]

As described above, according to the printing apparatus and the printing method of the present invention, a common power supply for two colors of K (black) and C (cyan), M (magenta) and Y
(Yellow), the load is reduced and the load of each power supply device is equalized as compared with the conventional common power supply for three or four colors. It is possible to reduce the rank of component parts such as transformers and FETs and to make each circuit common, eliminating the need for special large-capacity specifications, reducing the number of heat sinks required for large-capacity specifications, and reducing costs. , Miniaturization is realized.

According to the printing apparatus and the printing method of the present invention, in the monochrome mode, only the K (black) developing device is driven, and the C (cyan), M (magenta), and Y (yellow) developing devices are driven. Is stopped, image quality loss due to sleeve contamination of the developing roll is prevented.

According to the printing apparatus and the printing method of the present invention, in the black-and-white mode, the transfer unit and the charger of each YMC image forming unit are separated from the photosensitive member. The application of the high voltage power in the state of contact with the photoconductor is eliminated, and the deterioration of the photoconductor and the occurrence of fogging are prevented.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a schematic configuration of a printing apparatus according to the present invention.

FIG. 2 is a diagram illustrating a configuration of a power supply device of the printing apparatus according to the present invention.

FIG. 3 is a diagram illustrating a configuration of a developing device motor (Example 1) of the printing apparatus according to the present invention.

FIG. 4 is a diagram illustrating an operation state transition of the printing apparatus of the present invention.

FIG. 5 is a diagram showing a power supply and motor control configuration of the printing apparatus of the present invention.

FIG. 6 is a diagram showing a power supply and motor control processing flow of the printing apparatus of the present invention.

FIG. 7 is a diagram showing a developing device motor configuration (Example 2) of the printing apparatus of the present invention.

FIG. 8 is a diagram illustrating a configuration of a developing device motor using a clutch of the printing apparatus of the present invention.

FIG. 9 is a diagram illustrating a power supply, a motor, and a clutch control configuration of the printing apparatus of the present invention.

FIG. 10 is a diagram showing a power supply, a motor, and a clutch control processing flow of the printing apparatus of the present invention.

FIG. 11 is a diagram illustrating a retract configuration of the printing apparatus of the present invention.

FIG. 12 is a diagram illustrating a power supply and a BCR retract control configuration of the printing apparatus according to the present invention.

FIG. 13 is a diagram showing a cam configuration in a retract of the printing apparatus of the present invention.

FIG. 14 is a diagram illustrating a power supply and a BCR retract control processing flow of the printing apparatus of the present invention.

FIG. 15 is a diagram illustrating a power supply and a BTR retract control configuration of the printing apparatus of the present invention.

FIG. 16 is a diagram showing a power supply and BTR retract control processing flow of the printing apparatus of the present invention.

FIG. 17 is a diagram illustrating a configuration of a conventional printing apparatus.

FIG. 18 is a diagram showing a direct power supply configuration using a contact type roll and a minute discharge method in a minute gap.

[Explanation of symbols]

101 photoconductor, 102 charger, 103, developing device, 10
4 Primary transfer device, 105 peeling device, 251 separation capacitor, 301 developing device, 302 motor, 501 M
CU, 502, 503 High voltage power supply, 504, 505 motor 506, 507, 508, 509 Image forming unit 701, 702 motor, 801 motor, 802 clutch, 901 MCU, 902, 903 High voltage power supply,
904 motor 905 clutch 906, 907, 908, 909 image forming unit 1101 photoreceptor, 1102 charging device, 1103 developing device, 1104 primary transfer device 1201 MCU, 1202, 1203 high voltage power supply,
1204, 1205, 1206, 1207 Cam 1208, 1209, 1210, 1211 Image forming unit 1301 Photoconductor, 1302 charger, 1303 Cam 1304 Support member, 1305 Spring, 1306 Spring connection part 1501 MCU, 1502, 1503 High voltage power supply,
1504, 1505, 1506, 1507 Cam 1508, 1509, 1510, 1511 Image forming unit 1701 Photoreceptor, 1702 Charger 1703 Developing device, 1704 Primary transfer device 1705 Peeling device, 1706 Secondary transfer device

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03G 21/00376 G03G 21/00 398 398 372 (72) Inventor Takashi Sakamoto 2274 Hongo, Ebina-shi, Kanagawa Fuji Fuji Xerox Co., Ltd. Ebina Works F-term (reference) 2H027 ED03 ED08 ED24 EE02 EE04 EF09 FA28 ZA01 2H030 AA05 AB02 AD02 AD08 AD16 AD19 BB33 BB53

Claims (7)

[Claims] 1. A printing apparatus having an image forming mechanism for printing at least four colors including black and executing printing in a black and white print mode and a color print mode, wherein the image forming mechanism corresponding to black and another first color is provided. A first power supply for supplying power to a load of the mechanism in common; and a load for the image forming mechanism corresponding to the second color and the third color other than the black and the other first color. A second power supply device for supplying power; and a control unit for prohibiting operation of a load of the image forming mechanism corresponding to the first color during a black-and-white print mode operation. A printing apparatus for performing a process of prohibiting or canceling the operation of the load depending on whether the operation is in a color printing mode. 2. A load of the image forming mechanism corresponding to the first color is a developing device having a developing roll and rotating the developing roll with respect to a photosensitive member to perform development. 2. The printing apparatus according to claim 1, wherein the control unit executes control for inhibiting rotation of the developing roll of the developing unit in a black-and-white printing mode. 3. 3. The transfer mechanism according to claim 1, wherein a load of the image forming mechanism corresponding to the first color is a transfer device, and the transfer device moves the transfer device to a photoreceptor at a retract position separated from the transfer position. The operation of the load is a transfer to a photoreceptor of a transfer device, and the control unit controls the retractor mechanism to execute a retract that moves the transfer device from a transfer position to a retract position in a black-and-white printing mode. The printing apparatus according to claim 1, wherein the control is performed. 4. A load of the image forming mechanism corresponding to the first color is a charger, and the charger moves the charger to a retract position separated from a charging position with respect to the photosensitive member. The operation of the load is charging of the photoreceptor of the charger, the control means, during the black and white printing mode, the retractor mechanism to perform a retract to move the charger from the charging position to the retract position. The printing apparatus according to claim 1, wherein the control is performed. 5. The printing apparatus according to claim 1, wherein said image forming mechanism is a tandem type of four or more stations having image forming means for each color. 6. A printing method having a separate image forming unit for at least four colors including black and performing printing in a black-and-white print mode and a color print mode. And a second power supply device common to the image forming units for each of the colors other than the black and the other first color. In the black and white print mode, the first power supply device is provided. And turning on the first power supply and the second power supply in the color print mode. And printing method. 7. The printing method according to claim 1, further comprising a control step of prohibiting a load operation in the image forming unit of at least the first color excluding black, wherein the control step is a monochrome printing mode or a color printing mode. 7. The printing method according to claim 6, wherein a process of prohibiting or canceling the operation of the load is executed according to whether the printing is performed.