JP2007328197A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of minimizing wasteful cost and preventing image deterioration by optimizing the amount of toner adhering to a non-image part on a photoreceptor. <P>SOLUTION: In the image forming apparatus which uses an image carrier repeatedly to perform image forming by two or more times by forming an electrostatic latent image on an image carrier and making it a visible image with toner and also transferring a toner image to transfer material, the smaller the number of image forming times by a series of image forming operation from starting image-formation operation until finishing it is, the larger the amount of the toner adhering to the non-image part on the image carrier is made. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  In the present invention, an electrostatic latent image is formed on an image carrier and visualized with toner, and the toner image is transferred to a transfer material (transfer paper) and the image carrier is used repeatedly. In particular, the present invention relates to an image forming apparatus capable of preventing image deterioration by minimizing wasteful cost by optimizing the amount of toner to be deposited on a photoreceptor in a non-image area.

Conventionally, an image forming apparatus of a type in which an electrostatic latent image is formed on an image carrier and visualized with toner, and the toner image is transferred to a transfer material (transfer paper) and the image carrier is repeatedly used. Is well known. Such an image forming apparatus is configured as, for example, an electrophotographic copying machine, a printer, or a facsimile.
By the way, this type of image forming apparatus has various problems due to the toner adhering to the non-image portion photoconductor.

  As a prior art, Patent Document 1 discloses an image carrier capable of forming a latent image, and a developer carrier for visualizing the latent image formed on the image carrier as a developer image with a developer. And a transfer medium serving as a medium for transferring the developer image on the image carrier to a transfer material, and a movement amount detecting means for detecting a movement amount of the transfer medium, and the movement amount In the image forming apparatus in which the movement of the developer carrier is started based on the detection result by the detection unit, the image forming apparatus has a consumption detection unit for detecting the consumption amount of the developer, and the consumption detection unit detects the consumption amount detection unit. Based on the developer consumption amount and the movement amount of the transfer medium detected by the movement amount detecting means, an average value of the developer consumption amount is obtained, and when this average value is equal to or less than a predetermined value, the non-consumption on the image carrier is determined. The developer carried on the developer carrier adheres to the image forming area. It discloses a technique for.

  Patent Document 2 discloses that an activation current value of the drive motor of an image forming apparatus having means for cleaning residual toner on an image carrier with a motor-driven cleaning brush is detected, and this activation current value is a reference value (not filmed). If it is larger than the intermediate current value of the starting current value in the case of filming and filming, toner input is not performed. If it is smaller, it is determined that filming is about to occur and toner input to the cleaning means is performed. A technique for performing control to increase the amount and inputting toner at the end of the job is disclosed.

  In Patent Document 3, an image forming apparatus having an image carrier on which a developer image is formed on a surface, and a plate-like cleaning member that comes into contact with the image carrier and cleans the surface is further subjected to image formation. A print number detecting means for detecting the number of printed sheets and a developer consumption detecting means for detecting the amount of consumed developer, and depending on the detected number of printed sheets and developer consumption, A technique is disclosed in which a control developer image is formed on an image carrier at a timing other than the formation time, and the control developer image reaches a plate-like cleaning member.

Patent Document 4 discloses a fixing device in which a wall of a housing that stores an image forming unit (intermediate transfer belt) facing the cover wall of the fixing device is inclined and a space formed between the walls is opened upward. The high-temperature air containing water vapor generated in the process does not stagnate in the fixing device or between the image forming units, and is exhausted by convection to make it difficult to transfer heat to the image forming unit and to prevent the water vapor from adhering to the recording medium. Techniques for reducing are disclosed.
JP 2003-263027 A JP 2004-086107 A JP 2004-125900 A JP 2002-372818 A

As in the above conventional example, in order to prevent deterioration of image quality due to toner deterioration, to prevent melee of a blade for cleaning the photoconductor, and to prevent filming of the photoconductor, It is widely performed to form a toner consumption image pattern on a photoreceptor and to attach toner.
However, the toner deposited on the non-image area photoconductor does not become an image, and is discarded as waste toner in most cases, resulting in unnecessary costs for the user and poor ecology. was there. Therefore, it is necessary to minimize the amount of toner to be deposited on the non-image area photoreceptor.
The present invention has been made in order to solve the above-described conventional problems, and its purpose is to optimize the amount of toner deposited on the non-image portion photoconductor to minimize wasteful cost and to reduce image degradation. An object of the present invention is to provide an image forming apparatus that can be prevented.

In order to achieve the above-described object, the invention according to claim 1 forms an electrostatic latent image on an image carrier, visualizes the electrostatic latent image with toner, and uses the toner image as a transfer material. An image forming apparatus for transferring and repetitively using the image carrier to form an image a plurality of times, wherein the number of image formations by a series of image forming operations from the start to the end of the image forming operation is reduced. The amount of the toner to be deposited on the non-image area is increased.
According to a second aspect of the present invention, as the number of image formations by a series of image forming operations from the start to the end of the image forming operation is smaller, the toner is applied to the non-image portion on the image carrier at the end of image forming. The area of the consumption image pattern for attaching the ink is increased.
According to a third aspect of the present invention, as the number of image formations by a series of image forming operations from the start to the end of the image forming operation is smaller, the toner is applied to the non-image portion on the image carrier at the end of image forming. It is characterized in that the consumption image pattern for adhering is made longer.

According to the present invention, since simple detection means can be used, it is possible to optimize the amount of toner deposited on the photoconductor in the non-image area without increasing the complexity of the apparatus and the manufacturing cost. In addition to preventing this, it is possible to minimize wasteful costs caused to the user and reduce the burden on ecology.
Further, according to the present invention, the detection means for determining the amount of toner to be deposited on the non-image portion photoreceptor is only the number of images formed in a series of image forming operations from the start to the end of the image forming operation. Because this number of images is a means that most devices already have for the life of the device and for counter display for service price determination, no special detection means is required, thus complicating the device. There is no manufacturing cost.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a schematic view of an embodiment relating to a main part of an electrophotographic color printer which is an image forming apparatus according to the present invention.
As shown in FIG. 1, the configuration of the color printer of this embodiment is a color printer having a maximum sheet passing size of A3 size, and uses developers (toners) of yellow, magenta, cyan, and black colors. This is an intermediate transfer system configuration in which a developer image (toner image) is sequentially developed on a photoconductor as a first image carrier, and is superimposed on an intermediate transfer body as a second image carrier and transferred again to a transfer material. is there. The toner that cannot be transferred onto the transfer material and remains on the intermediate transfer member is removed by the cleaning device 9 to prepare for the next printing process.

  First, a developing process for forming a toner image on a photoconductor will be described. As the photoconductor, a drum-shaped photoconductor drum 1 is used. The photoconductor drum 1 rotates in the direction of an arrow R1 and is uniformly charged by a charger 2. Then, an image exposure L by a laser beam is given from the LD driver 3 serving as an exposure apparatus through the polygon mirror 18 and the reflection mirror 4 at the exposure position A, and an electrostatic latent image is formed.

The electrostatic latent image formed on the photosensitive drum 1 is developed by the developing device 5. The developing device 5 is a rotary developing device equipped with a yellow developing device 5Y, a magenta developing device 5M, a cyan developing device 5C, and a black developing device 5Bk, each containing yellow, magenta, cyan, and black toners. A developing unit corresponding to the color of the toner image to be formed is opposed to the photosensitive drum 1 to develop the electrostatic latent image on the photosensitive drum 1, and a yellow toner image, a magenta toner image, a cyan toner image, black A developer image (toner image) of each color as a toner image is formed.
In such an image forming apparatus, the direction in which the laser beam is scanned, that is, the direction intersecting the moving direction of the intermediate transfer belt 6 is the main scanning direction, and the direction in which the photosensitive drum 1 and the intermediate transfer belt 6 are moving is the sub-scanning direction. Called.

Next, a primary transfer process from the photoreceptor to the intermediate transfer body and a secondary transfer process from the intermediate transfer body to the transfer material will be described.
In the primary transfer nip portion B, the toner images of the respective colors formed on the photosensitive drum 1 are transferred to the intermediate transfer belt 6 as an intermediate transfer member in the direction R2 that is the forward direction and the rotational direction R1 of the photosensitive drum 1. During the circumferential rotation, the primary transfer roller 7 to which the primary transfer bias is applied from the power source 12 sequentially performs primary transfer on the surface thereof, and a full color toner image in which four colors are superimposed is formed on the intermediate transfer belt 6. The

Here, a belt-like intermediate transfer belt 6 is used as an intermediate transfer member that is a second image carrier, and the intermediate transfer belt 6 is stretched by a driving roller 6a, a secondary transfer counter roller 6b, and a tension roller 6c. It is a resin belt that rotates in the direction of arrow R2 by the rotational drive of the drive roller 6a.
The full-color toner image formed on the intermediate transfer belt 6 in this way is collectively transferred to the transfer material P to be fed at the secondary transfer nip C.

The secondary transfer nip C is a nip portion between the secondary transfer roller 8 serving as a transfer unit and the intermediate transfer belt 6. The secondary transfer roller 8 comes into contact with the intermediate transfer belt 8 from the back side of the transfer material P only at the time of image transfer, and the secondary transfer counter roller 6b is used as a counter electrode, and a positive polarity bias is applied to the secondary transfer roller 8 from a high voltage power source 13. Apply. The secondary transfer efficiency of the toner is about 90% in the image forming apparatus shown in this embodiment.
FIG. 2 is a schematic configuration diagram of a secondary transfer nip C where the toner is secondarily transferred from the intermediate transfer belt 6 to the transfer material P, and a downstream portion of the secondary transfer nip C in the moving direction of the intermediate transfer belt 6. 90% of the toner 21 is transferred from the intermediate transfer belt 6 onto the transfer material P, and the remaining 10% of the toner 22 remains on the intermediate transfer belt 6. The toner image 21 transferred onto the transfer material P is fixed onto the transfer material P by a fixing device (not shown).

Next, a description will be given of a cleaning device that is located downstream of the secondary transfer nip in the direction of movement of the intermediate transfer body and removes toner remaining on the intermediate transfer body after secondary transfer. The toner 22 remaining on the intermediate transfer belt 6 is And removed by the cleaning device 9 to prepare for the next cycle.
In such an image forming apparatus, in order to prevent deterioration in image quality due to toner deterioration, in order to prevent a blade from cleaning the photosensitive drum 1, or in order to prevent filming of the photosensitive drum 1. The toner consumption image pattern is formed on the photosensitive drum 1 in the non-image area to adhere the toner.

Next, as a feature of the present invention, the toner consumption image pattern formation time (sub-scanning length of the toner consumption image pattern) formed on the non-image portion on the photosensitive drum 1 at the end of image formation by the number of images per one-time image formation. A method for preventing image deterioration by minimizing useless cost will be described.
In such an image forming apparatus, in order to form an image in a place where the photosensitive drum 1 and the intermediate transfer belt 6 have been cleaned, the photosensitive drum 1 is used when the photosensitive drum 1 and the intermediate transfer belt 6 start to move by the start of image formation. In addition, it is necessary to wait until the position where the intermediate transfer belt 6 is in front of each cleaning unit first reaches the photosensitive drum 1, and during this time, each color developing device 5 rotates idly without consuming or replenishing toner.
In addition, when the image formation is finished, in order to finish cleaning the place where the image on the photosensitive drum 1 or the intermediate transfer belt 6 where the image is formed, wait until the place where the transfer is finished reaches each cleaning unit. During this period, each color developing device 5 rotates idly without consuming or replenishing toner.

In the image forming apparatus as shown in FIG. 1, the peripheral length of the intermediate transfer belt 6 is longer than the peripheral length of the photosensitive drum 1, and the time required for the start and end of image formation becomes longer as the peripheral length of the intermediate transfer belt 6 becomes longer. Become.
The time required to start and end the image formation is the same regardless of whether a large number of images are continuously formed or only one image is formed. Since the time required for the start end of the image is large, the time required for the start-end when only one image is formed in the case of image formation of a large number of sheets is negligibly small. Is added as it is. In the image forming apparatus as shown in FIG. 1, the time required for the start end is longer than the time required for the single image formation.

Even if the developing device 5 is idled for only one start / end time, the toner is hardly deteriorated and the image image is not deteriorated. The toner change due to the consumption and replenishment cannot catch up, and the toner deterioration due to idle rotation of the developing device due to the start-end time accumulates, and abnormal images such as missing characters (worm-eaten) and vomit are generated.
Depending on the time required for the start and end of the image forming apparatus, when 5 to 10 or more images are formed, toner consumption due to image formation and toner replacement due to replenishment are superior, and image deterioration due to toner deterioration is almost eliminated.
In view of such a situation, in the present invention, the toner consumption image pattern formation time (sub-order of the toner consumption image pattern) formed on the non-image portion on the photosensitive drum 1 at the end of image formation by the number of images per one image formation. (Scanning length) is changed to minimize wasteful cost and prevent image deterioration.

  That is, in this embodiment, as shown in FIG. 3, when the number of image formation is 1, the consumption image pattern sub-scanning length is 12 mm, and when the number of image formation is 2, the consumption image pattern sub-scanning length is 1 6 mm of 1/2 of 12 mm of the sheet, 3 mm of 1/3 for the 3 sheets, 3 mm of 1/4 for the 4 sheets, 2 mm at the average of 1/5 to 1/10 for the 5-10 sheets, For 10 sheets or more, the thickness was 1/10 of 1/10. The reason why the number is increased to 10 mm when the number of sheets is 10 or more is that the cleaning blade curling effect as described in JP-A-2004-125900 is aimed at, and for the purpose of preventing abnormal images due to toner deterioration, it is constant. The number of sheets or more may be 0 mm. FIG. 3 is a diagram showing a table in which the formation time of the toner-consumed image pattern formed on the non-image portion by the number of images per one-time image formation is set.

That is, as the number of image formations (number of image formations) by a series of image formation operations (image formation operations) from the start to the end of the image formation operation decreases, the toner adheres to the non-image portion on the photosensitive drum 1 (image carrier). Try to increase the amount of.
In other words, the smaller the number of image formations in a series of image forming operations from the start to the end of the image forming operation, the more toner adheres to the photosensitive drum 1 (image carrier) in the non-image area at the end of image forming. Therefore, the area of the consumed image pattern is increased.

The operation in this case will be described with reference to the flowchart of FIG.
FIG. 4 is an operation flowchart for determining the length of the toner consumption image pattern formed in the non-image portion at the end of image formation.
Here, the toner consumption image pattern has a substantially maximum image width in the LD main scanning direction, and all the toner of this pattern is collected by the cleaning device, so that the pattern is 50% so as not to overload the cleaning device.
In step 101 of FIG. 4, when an image formation start signal is received, driving is started by a subsequence of image formation start of the apparatus. In steps 103 and 105, an image formation signal is received and a subsequence is generated when the image formation timing comes. Perform image movement. At this time, one counter 20 (see FIG. 1) provided in the control system is counted up for each image forming signal. This will tell you how many images have been created. In the case of device control in which the number of image formations is known in advance, the counter is unnecessary and it is sufficient to bring the number of image formations as it is.

Next, when the image formation end signal is received, the image formation is terminated in step 107, the table of the number of image formations in the consumption image pattern length table shown in FIG. The sub-scan length (time) of the image pattern is determined, and in step 113, the pattern is output for this length, and then the drive of the apparatus is stopped by a sub-sequence for stopping the apparatus.
Further, as another embodiment for determining the sub-scanning length (time) of the consumption image pattern, the length of the toner consumption image pattern in the case of one image formation is Lmm (12 mm in this apparatus), and the number of image formation is N sheets. As an alternative, the length of the toner consumption image pattern in the case of N image forming may be set to L / Nmm.

1 is a schematic view of an embodiment relating to a main part of an electrophotographic color printer which is an image forming apparatus according to the present invention. FIG. 2 is a schematic configuration diagram of a secondary transfer nip in which toner is secondarily transferred from an intermediate transfer belt to a transfer material illustrated in FIG. 1 and a downstream portion of the secondary transfer nip in the moving direction of the intermediate transfer belt. It is a diagram showing a table in which the formation time of a toner consumption image pattern to be formed on a non-image part by the number of sheets per one-time image formation is set. 6 is an operation flowchart for determining the length of a toner consumption image pattern formed in a non-image portion at the end of image formation.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Photosensitive drum, 2 ... Charger, 3 ... LD driver, 4 ... Reflection mirror, 5 ... Developing device, 5Bk ... Black developing device, 5C ... Cyan developing device, 5M ... Magenta developing device, 5Y ... Yellow developing device, 6 ... intermediate transfer belt, 6a ... driving roller, 6b ... secondary transfer counter roller, 6c ... tension roller, 7 ... primary transfer roller, 8 ... intermediate transfer belt, 9 ... cleaning device, 12 ... power source, 13 ... high voltage power source, 18 ... polygon mirror, 20 ... counter, 21 ... toner, 21 ... toner image, 22 ... toner

Claims (3)

  An electrostatic latent image is formed on the image carrier, and the electrostatic latent image is visualized with toner. The toner image is transferred to a transfer material, and the image carrier is used repeatedly to form an image multiple times. In the image forming apparatus, the amount of the toner adhered to the non-image portion of the image carrier is increased as the number of times of image formation by a series of image forming operations from the start to the end of the image forming operation is decreased. An image forming apparatus.   As the number of times of image formation by a series of image forming operations from the start to the end of the image forming operation is smaller, the area of the consumed image pattern for attaching the toner to the non-image portion on the image carrier at the end of image forming The image forming apparatus according to claim 1, wherein:   The smaller the number of times of image formation by a series of image forming operations from the start to the end of the image forming operation, the longer the consumed image pattern for attaching the toner to the non-image portion on the image carrier at the end of image forming. The image forming apparatus according to claim 1.

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