JP3659587B2 - Image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a color image forming apparatus such as a copying machine, a printer, and a facsimile using an electrophotographic system.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, developing devices containing a two-component developer composed of toner and carrier for each color of yellow, magenta, cyan, and black are arranged in parallel around one photosensitive drum, and image formation is performed by an electrophotographic method. Color image forming apparatuses such as copying machines, printers, and facsimiles have been proposed. This image forming apparatus forms an electrostatic latent image on the surface of each photosensitive drum for each color, and sequentially supplies a developer of a color corresponding to each electrostatic latent image from each developing apparatus to form a toner image for each color. A color image is formed by superimposing the images of the respective colors on a transfer roller in contact with the photosensitive drum, and then the color image is transferred to a recording sheet.
[0003]
This image forming apparatus is often provided with a single-color mode printing function for performing printing with only one color designated by the user regardless of the color of the image on the document (image to be printed). When performing monochrome mode printing, it is necessary to prevent the developer from being supplied to the photosensitive drum from a developing device containing a developer other than the color used for printing. The developing device conveys the developer agitated by the agitation roller to the surface of the photosensitive drum by the developer supply roller (pumping roller). However, in the developing device containing the color developer not used for printing, the developing device By stopping the rotation of the developer supply roller, the conveyance of the developer is stopped and the developer is not supplied to the surface of the photosensitive drum.
[0004]
[Problems to be solved by the invention]
However, if the developer supply roller is stopped and only the stirring roller is rotated, the developer does not circulate in the developing device, so that the developer moves toward one end of the stirring roller and is biased. The “agent drop” occurs where the developer leaks outside. Therefore, at the time of printing in the single color mode, every time printing on one sheet of recording paper is completed, the photosensitive drum is rotated in a state where no electrostatic latent image is formed, and the colors not used in the single color mode printing are The developer supply roller and the agitation roller of the developing device in which the developer is accommodated are rotated to circulate the developer, thereby eliminating the bias of the developer in the developing device and preventing the occurrence of the “agent dropping”. . In other words, even during single color mode printing, the same operation as during full color printing in which developer is supplied from all the developing devices to the photosensitive drum is performed. As a result, even when performing mono-color mode printing, the same printing time as full-color printing is required, so printing in mono-color mode is an inefficient operation, and shortening of the printing time is desired. . In particular, when printing a large number of copies in the single color mode, a lot of wasted printing time occurs.
[0005]
The present invention has been made to solve the above-described problems, and improves the printing speed in the single-color mode while preventing the occurrence of the “agent dropout” problem without changing the configuration of the developing device. An object of the present invention is to provide an image forming apparatus that can perform the above-described process.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the invention described in claim 1 is configured to sensitize a two-component developer composed of toner and a carrier around one photosensitive drum and a developer agitated by the agitation roller. A plurality of developing devices each having a developer supply roller for supplying to the surface of the photosensitive drum are arranged in parallel, and each developing device is sequentially used to form a toner image of each color on the photosensitive drum, and each color toner image is transferred to the intermediate transfer member. In an image forming apparatus that forms a color image by transferring the image on top of it,
When there is a developing device that does not supply developer to the photosensitive drum during execution of a print job among the plurality of developing devices, a stirring roller and a developing roller that does not supply the developer after completion of the print job. Perform an aging operation to rotate the developer supply roller ,
When an image cannot be formed even if the print job is not completed, the developing device that does not supply the developer performs the aging operation .
[0007]
Conventionally, for example, when printing a plurality of copies in a single-color mode, an aging operation of a developing device that does not supply a developer is performed every time one sheet is printed, thereby preventing "agent dropping". Therefore, although it took a long time to finish the print job, in this configuration, during the execution of the print job, the aging operation of the developing device that does not supply the developer is not performed, and the multiple sheets are printed. The aging operation is performed after all the operations are completed. Therefore, since the aging operation is not performed during the execution of the print job, the print job can be completed in a shorter time than before. In addition, it is possible to improve the printing speed in the single color mode while preventing “agent dropping” without adding a special mechanism for preventing “agent dropping” to the developing device.
[0008]
Generally, when the developer supply roller of the developing device that does not supply the developer has been stopped for a long time, the aging operation time needs to be increased, and when the stop time of the developer supply roller is short, the aging of the developing device is required. The operation time is short (it may not be a problem if the aging operation is not performed depending on the stop time of the developing device), but this configuration changes the aging time according to the number of print jobs. Further, it is possible to avoid the aging operation being performed unnecessarily for a long time, and it is possible to prevent the occurrence of charge-up in which the charge amount of the toner in the developer becomes excessive due to long-time stirring.
[0009]
In addition , if the print job is not completed, it is impossible to form an image. Utilizing this, the developing device that does not supply the developer performs the aging operation, so that it is not necessary to secure time for the aging operation after the print job is completed.
[0010]
Further, an invention according to claim 2, in the image forming apparatus according to claim 1, even when the image forming apparatus body cover can not execute the print job is opened and closed, not replenished toner development The apparatus does not perform the aging operation.
[0011]
In this configuration, even when the image forming apparatus main body cover is opened and closed and the print job cannot be executed, the aging operation is not performed for the developing device not additionally supplied with toner, for example, additional toner is supplied. The aging operation is performed only for the developing device in which the charge amount is clearly insufficient. As a result, unnecessary aging operation can be avoided, and charging of the toner in the developer can be prevented.
[0012]
According to a third aspect of the present invention, in the image forming apparatus according to the first or second aspect , the fixing roller for fixing the developer transferred to the recording paper to the recording paper when the power of the image forming apparatus is input. The aging operation is not performed for a developing device that has reached a predetermined temperature and is not additionally supplied with toner.
[0013]
According to this configuration, even when the power of the image forming apparatus is input, the aging operation is not performed for the developing apparatus in which the fixing roller has reached a predetermined temperature and the developer is not additionally supplied. For example, the aging operation is performed only for a developing device in which toner is replenished and the charge amount is apparently insufficient. As a result, unnecessary aging operation can be avoided, and charging of the toner in the developer can be prevented.
[0014]
According to a fourth aspect of the present invention, an agitating roller for agitating a two-component developer composed of toner and a carrier and a developer agitated by the agitating roller are supplied to the surface of the photoreceptor drum around one photoreceptor drum. A plurality of developing devices each having a developer supplying roller are arranged side by side, and each developing device is used in order to form a toner image of each color on the photosensitive drum, and each color toner image is superimposed on the intermediate transfer member and transferred. In an image forming apparatus for forming a color image,
According to the total number of prints when all of these print jobs are executed when performing a plurality of print jobs in a single color mode in which printing is performed using only one color developer, without any time interval. Determining the time of the aging operation for rotating the stirring roller and the developer supply roller to be performed by the developing device that has not supplied the developer to the photosensitive drum after completion of all the print jobs. It is.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an image forming apparatus according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a schematic configuration of an image forming unit of an image forming apparatus according to the present invention. A copying machine (an example of an image forming apparatus) 1 according to an embodiment of the present invention includes a photosensitive drum 2 that is rotationally driven in the direction of arrow A in FIG. Around the photosensitive drum 2, the charging device 3, the exposure device 4, the developing devices 5Y, 5M, 5C, and 5K for each color of yellow, magenta, cyan, and black, the intermediate transfer roller 6 and the cleaning are arranged in the order of the image forming process. A device 7 is arranged. These developing devices 5Y, 5M, 5C and 5K contain a two-component developer composed of toner and carrier.
[0016]
At the time of image formation, the photosensitive drum 2 is uniformly charged by the charging device 3, and a laser beam or the like is irradiated from the exposure device 4 onto the surface of the photosensitive drum 2 to form an electrostatic latent image. The electrostatic latent image is formed for each color, and a developer of a color corresponding to each electrostatic latent image is supplied from the developing devices 5Y, 5M, 5C, and 5K, and a toner image is formed for each color. Is temporarily transferred onto the intermediate transfer body roller 6 in contact with the toner. A color image is formed on the intermediate transfer roller 6 by superimposing the images of the respective colors. A transfer roller 9 is provided below the intermediate transfer body roller 6 so as to be pressed against the photosensitive drum 2, and when the recording paper P is conveyed to the nip portion between the intermediate transfer body roller 6 and the transfer roller 9. Further, the color image on the intermediate transfer body roller 6 is transferred to the recording paper P.
[0017]
FIG. 2 is a schematic diagram showing the internal configuration of the developing device 5K. The developing device 5K containing the black developer is provided with a stirring roller 51, a developer supply roller 52, a developer conveying roller 53, and a developer peeling roller 54. By these rollers, the developing device 5K is provided. The toner and carrier inside are agitated and conveyed to the photosensitive drum 2, and the developer remaining after the development is circulated again in the developing device 5 </ b> K and conveyed to the photosensitive drum 2.
[0018]
The agitation roller 51 mixes toner and carrier and frictionally charges them. The stirring roller 51 extends in the direction of the rotation axis of the photosensitive drum 2, and a spiral blade 512 is attached around the rotation shaft 511 of the stirring roller 51. The developer 100 is agitated by the rotation of the spiral blade 512 in the direction of the arrow R 1 and is conveyed toward the developer supply roller 52.
[0019]
The developer supply roller 52 is provided above the stirring roller 51 so as to face the photosensitive drum 2. The developer supply roller 52 extends in the rotation axis direction of the photosensitive drum 2 and extends over substantially the entire development area. The developer supply roller 52 includes a cylindrical developing sleeve 521 made of a nonmagnetic material such as aluminum, and a magnet material 522 disposed inside the developing sleeve 521. The developer 100 is attracted to the surface of the developing sleeve 521 by the magnetic force of the magnet material 522, and the developer 100 adhering to the surface of the developing sleeve 521 is pumped up by rotating in the direction of arrow R2, and moves to the photosensitive drum 2 side. It is supposed to be. After supplying the developer 100 to the photosensitive drum 2, the surplus developer 100 is transported to the developer transport roller 53 by the developer supply roller 52.
[0020]
At a position facing the developer supply roller 52, a developer peeling roller 54 is provided that makes the amount of the developer 100 that the developer supply roller 52 supplies to the photosensitive drum 2 constant. The developer peeling roller 54 is disposed over substantially the entire region in the rotation axis direction of the developing sleeve 511 of the developer supply roller 52.
[0021]
The developer transport roller 53 is also disposed so as to extend in the direction of the rotation axis of the photosensitive drum 2. The developer transport roller 53 includes a cylindrical developing sleeve 531 made of a nonmagnetic material such as aluminum, and a magnet material 532 disposed inside the developing sleeve 531. The developer 100 is attracted to the surface of the developing sleeve 531 by the magnetic force of the magnet material 532, and the developer 100 on the surface of the developing sleeve 531 moves toward the stirring roller 51 by rotating in the direction indicated by the arrow R3 in FIG. . The developer conveyed to the stirring roller 51 by the developer conveying roller 53 is stirred and mixed by the stirring roller 51 and used for the next development. The toner supply is performed from the toner cartridge 55 above the stirring roller 51.
[0022]
Although the configuration of the developing device 5K has been described above, the developing devices 5Y, 5M, and 5C that contain developers of other colors have substantially the same configuration. However, the developing devices 5Y, 5M, and 5C need only move the developer in the horizontal direction from the stirring roller 51 for the convenience of arrangement with respect to the photosensitive drum 2. The roller 51, the developer supply roller 52, and the developer transport roller 53 may be arranged in parallel in the horizontal direction.
[0023]
FIG. 3 is a block diagram showing a schematic configuration of the copying machine 1. The copying machine 1 includes a control device 20 that controls the entire copying machine 1. The control device 20 controls the aging operation of the developing device described later. The control device 20 includes a charging device 3, an exposure device 4, and developing devices 5Y, 5M, 5C, and 5K, a fixing device 12 that pressurizes and heat-fixes the toner transferred onto the recording paper, and the intermediate transfer roller 6. And a transfer device 15 including a transfer bias unit and the like. The control device 20 also includes a drum motor 21 that drives the photosensitive drum 2, a static elimination device 22 that removes residual charges on the surface of the photosensitive drum 2 after the toner image is transferred, and a recording paper for image formation and recording paper discharge. The paper transport mechanism 23 for transporting the document and the document reading device 24 for reading the document image are driven and controlled.
[0024]
The control device 20 is also connected to a ROM 251 storing a program for controlling the operation of the copying machine 1 and a memory 25 including a RAM 252 used as a work area for each program. Further, the control unit 20 includes an operation unit 27 including a print key for inputting a print instruction, a numeric keypad for inputting the number of prints, and the like, various functions that can be operated by the copier 1, trouble situations such as a paper jam, and the like. A display device 28 composed of a liquid crystal panel or the like for display is connected.
[0025]
The stirring roller 51, the developer supply roller 52, and the developer transport roller 53 of the developing devices 5Y, 5M, and 5C are rotationally driven by the same stirring motor 60. The stirring roller 51, the developer supply roller 52, and the developer transport roller 53 of the developing device 5 </ b> K are rotationally driven by a stirring motor 61 that is separate from the stirring motor 60. In each developing device, the agitation roller 51 is configured to be rotatable and driven separately from the developer supply roller 52.
[0026]
Next, operation control of the developing devices 5Y, 5M, 5C, and 5K during image formation by the copying machine 1 will be described. The copying machine 1 according to the present invention uses the idle time during which image formation is not performed when there is a developing device that does not supply toner to the photosensitive drum 2 at the time of image formation at the time of monochromatic mode printing. An aging operation in which the agitation roller 51, the developer supply roller 52, and the developer transport roller 53 are rotationally driven on the developing device (the developer is put on the developer supply roller 52, but the surface of the photosensitive drum 2 is statically moved). An electrostatic latent image is not formed and the developer is not supplied to the photosensitive drum 2), and the developer is circulated in the developing device, whereby the developer leaks out of the developing device. Is prevented.
[0027]
Whether or not to execute the aging operation is controlled as follows. FIG. 4 is a flowchart of the aging operation control. At the time of image formation, it is determined in which print mode the print job to be executed is to be printed (S1). In this determination, when the print job is printing that requires the supply of the developer from all the developing devices 5Y, 5M, 5C, and 5K to the photosensitive drum 2, for example, full color printing, the photosensitive member. In order to supply the developer to the drum 2, the stirring roller 51, the developer supply roller 52, and the developer transport roller 53 of each of the developing devices 5Y, 5M, 5C, and 5K rotate. Since there is no fear, the aging operation is not performed for any of the developing devices (S5).
[0028]
In S1, when printing is performed in a single color mode in which printing is performed with only one color designated by the user regardless of the color of the image on the document (image to be printed), yellow, magenta, cyan, and black are printed. When printing using only one color developer, the process proceeds to S2 and subsequent steps. Also, in S1, when printing is performed in a single color mode and printing is performed in red, green, and blue, since the black developer is not supplied from the developing device 5K to the photosensitive drum 2, the process proceeds to S2 and subsequent steps.
[0029]
If it is determined in S1 that there is a developing device that does not supply developer to the photosensitive drum 2 such as a monochrome mode that uses a developer of only one of yellow, magenta, cyan, and black, it is currently being executed. After the print job is completed (YES in S2), it is determined how many sheets (number of copies) have been printed by executing the print job (S3). In this determination, if the number of printed sheets is 10 or less, no aging operation is performed for any of the developing devices (S5). When the number of printed sheets is 10 or less, the rotation of the developer supply roller 52 and the developer transport roller 53 of the developing device that does not supply the developer to the photosensitive drum 2 is stopped (only the stirring roller 51 is rotating). This is because the trouble of “drug removal” is unlikely to occur even if the aging operation is not performed.
[0030]
If it is determined in S3 that the number of printed sheets is 11 to 100, the developing device that has not supplied the developer to the photosensitive drum 2 is aged for about 30 seconds (S4), and the number of printed sheets is 101. In the above case, the developing device is aged for about 60 seconds (S8). Generally, when the developer supply roller 52 of the developing device that does not supply the developer has been stopped for a long time, it is necessary to lengthen the aging operation time. When the stop time of the developer supply roller 52 is short, the development is performed. Since the aging operation time of the apparatus is short, the developing apparatus that does not supply the developer stops the rotation of the developer supply roller 52 and the developer transport roller 53 (the time when only the stirring roller 51 is rotated). This is because the aging operation is performed at an appropriate time according to the above. However, the number of printed sheets and the aging operation time corresponding to the number of printed sheets are merely examples, and are appropriately changed according to the performance of each developing device, the properties of toner and carrier, and the like.
[0031]
It should be noted that the aging operations of the developing devices that did not supply the developer to the photosensitive drum 2 are preferably performed simultaneously (in this embodiment, the stirring roller 51, the developer supply roller 52, and the developing device 5Y, 5M, and 5C) Since the developer transport roller 53 is rotationally driven by the same stirring motor 60, the aging operations of the developing devices 5Y, 5M, and 5C are necessarily performed simultaneously. During this aging operation, an electrostatic latent image is not formed on the surface of the photosensitive drum 2, so that even if each developing device rotates the developer supply roller 52 at the same time, the developing device supplies the developer to the photosensitive drum 2. Does not adhere. However, the aging operation may be performed separately with a time difference for each developing device.
[0032]
In this way, by preventing the aging operation from being performed until the print job is completed, in the case of printing a plurality of sheets, the print job is more effective than the conventional image formation in which the aging operation is performed every time one print is completed. Can be completed in a short time. In addition, it is not necessary to add a special mechanism for preventing “agent dropping” to the developing device.
[0033]
Even if the print job has not ended (NO in S2), there is no recording paper of the specified size (NO in S6), and return is performed using printing paper of another size instead. When the priority mode is not set (NO in S7), an aging operation corresponding to the number of printed sheets is performed (S3, S4, S5, S8). Under such circumstances, a print job is interrupted, and a free time is generated in printing. Therefore, an aging operation can be performed without affecting printing by performing an aging operation using this free time. Can do.
[0034]
Further, since the copying machine 1 is provided separately from the stirring motor 60 of the developing devices 5Y, 5M, and 5C and the stirring motor 61 of the developing device 5K, even if one is driven, the other is stopped. It is also possible to make it. Therefore, when performing black single color mode printing, the aging operation for the developing devices 5Y, 5M, and 5C can be omitted by stopping the stirring motor 60 of the developing devices 5Y, 5M, and 5C. is there. Similarly, when performing monochrome mode printing of yellow, magenta, and cyan, the aging operation for the developing device 5K can be omitted if the stirring motor 61 of the developing device 5K is stopped (however, In this case, the stirring motor 61 of the developing device 5K is not used as a drive source for other mechanisms such as a cleaning mechanism for the intermediate transfer roller 6, and even if the stirring motor 61 is stopped, image formation is not hindered. Is a requirement).
[0035]
In addition, this invention is not restricted to the structure of the said embodiment, A various deformation | transformation is possible. For example, in order to prevent the toner in the developer from being charged up (overcharged), the aging operation may be controlled at a time other than the time of image formation. FIG. 5 is a flowchart showing an example of the aging operation control. For example, (1) Even when the main body cover of the copying machine 1 is opened and closed and image formation is stopped (YES in S11), if no additional toner is supplied (NO in S12), an aging operation is performed. (S13) (2) Even when the temperature of the fixing roller of the fixing device 12 is equal to or higher than a predetermined temperature even when warming up after the power of the copying machine 1 is turned on (YES in S14), that is, The aging operation may not be performed when the fixing roller temperature has reached a fixable temperature, or when the fixing roller temperature has reached the fixing temperature by a short warm-up operation (S13). By performing such an aging operation control, it is possible to avoid a situation where the stirring of the developer by the stirring roller 51 is performed unnecessarily for a long time, and to prevent the toner in the developer from being charged up.
[0036]
In the above embodiment, a case where one print job for printing in the single color mode is executed is described. For example, when a plurality of print jobs in the single color mode are continuously performed without a time interval, The aging operation time (or whether to perform the aging operation) of the developing device that does not supply the developer to the photosensitive drum 2 is determined according to the total number of printed sheets when all these print jobs are executed. Also good.
[0037]
【The invention's effect】
As described above, according to the present invention, during the execution of the print job, the aging operation of the developing device that does not supply the developer is not performed, and the aging operation is performed after all the printing of the plurality of sheets is completed. Since the aging operation is not performed during the execution of the job, the print job can be completed in a shorter time than before. In addition, it is possible to improve the printing speed in the single color mode while preventing “agent dropping” without adding a special mechanism for preventing “agent dropping” to the developing device.
[0038]
In addition, if the aging time is changed according to the number of print jobs, the aging operation can be avoided from being performed unnecessarily for a long time, and the charge amount of the toner in the developer becomes excessive due to long-time stirring. It is possible to prevent the occurrence of charge up.
[0039]
Further, when an image cannot be formed even if the print job has not ended, the aging operation is performed on the developing device that does not supply the developer by using the interruption time of the print job. By doing so, it is possible to eliminate the need to secure time for the aging operation after the print job is completed.
[0040]
Even if the image forming apparatus main body cover is opened and closed and a print job cannot be executed, if the above-described aging operation is not performed for a developing device that is not additionally supplied with toner, for example, additional toner is supplied. Thus, the aging operation is performed only for the developing device in which the charge amount is clearly insufficient, and unnecessary aging operation can be avoided to prevent the toner in the developer from being charged up.
[0041]
Further, even when the power of the image forming apparatus is input, if the developing roller that has reached the predetermined temperature and is not additionally supplied with the developer is not allowed to perform the aging operation, For example, the aging operation is performed only for the developing device in which the toner is replenished and the charge amount is apparently insufficient, and unnecessary aging operation can be avoided to prevent the toner in the developer from being charged up. become.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a schematic configuration of an image forming unit of an image forming apparatus according to the present invention.
FIG. 2 is a schematic diagram illustrating an internal configuration of a developing device.
FIG. 3 is a block diagram illustrating a schematic configuration of an image forming apparatus according to the present invention.
FIG. 4 is a flowchart showing aging operation control for the developing device.
FIG. 5 is a flowchart illustrating an example of aging operation control at a time other than image formation.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Copying machine 2 Photosensitive drum 5Y, 5M, 5C, 5K Developing device 6 Intermediate transfer body roller 9 Transfer roller 20 Control device 51 Stirrer roller 52 Developer supply roller 53 Developer transport roller 54 Developer peeling roller 60Y, 60M, 60C , 60K Stirrer motor 100 Developer

Claims (4)

A developing device provided with a developer roller for stirring a two-component developer composed of toner and a carrier, and a developer supply roller for supplying the developer stirred by the stirring roller to the surface of the photosensitive drum, around one photosensitive drum. In an image forming apparatus in which a plurality of toner images of each color are formed on a photosensitive drum using a plurality of developing devices in order, and a color image is formed by transferring each color toner image on an intermediate transfer member. ,
When there is a developing device that does not supply developer to the photosensitive drum during execution of a print job among the plurality of developing devices, a stirring roller and a developing roller that does not supply the developer after completion of the print job. Perform an aging operation to rotate the developer supply roller ,
An image forming apparatus that causes a developing device that does not supply the developer to perform the aging operation when an image cannot be formed even if the print job is not completed . Even if the image forming apparatus body cover can not execute the print job is opened and closed, the image forming apparatus according to I請 Motomeko 1 such to perform the aging operation in the developing device not replenished toner. When the power of the image forming apparatus is input, the fixing roller for fixing the developer transferred onto the recording paper reaches a predetermined temperature, and the aging operation is performed on the developing apparatus that is not additionally supplied with toner. the image forming apparatus according to Align a I請 Motomeko 1 or claim 2. A developing device provided with a developer roller for stirring a two-component developer composed of toner and a carrier, and a developer supply roller for supplying the developer stirred by the stirring roller to the surface of the photosensitive drum, around one photosensitive drum. In an image forming apparatus in which a plurality of toner images of each color are formed on a photosensitive drum using a plurality of developing devices in order, and a color image is formed by transferring each color toner image on an intermediate transfer member. ,
According to the total number of prints when all of these print jobs are executed when performing a plurality of print jobs in a single color mode in which printing is performed using only one color developer, without any time interval. Then, after all the print jobs are finished, an image for determining the time of the aging operation for rotating the stirring roller and the developer supply roller to be performed by the developing device that did not supply the developer to the photosensitive drum. Forming equipment.

Images