JP3189851B2 - Multicolor image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-color image forming apparatus such as a copying machine, a facsimile, a printer, and the like.
The present invention relates to a multi-color image forming apparatus that collectively transfers the superimposed toner image onto a transfer material.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus using an electrophotographic system, a corona charger which can obtain uniform charging very easily is often used as a charger. This corona discharger also has the advantage that sufficient charge can be obtained even when the image carrier is run at a high speed. However, the disadvantage is that ozone is generated at the time of corona discharge and the photoconductor on the surface of the image carrier is damaged. This may affect the charging performance and cause deterioration of the photoreceptor such as a reduction in the charging potential. This tendency of deterioration is much stronger in negative discharge than in positive discharge. Recently, an organic photoreceptor (OPC) has been increasingly used as a photoreceptor, but since only OPC for negative charging has been put into practical use, deterioration of the photoreceptor has become a problem.

[0003] In the conventional image forming apparatus, in order to solve the above-mentioned problems, air is blown toward the charger, or ozone accumulated around the charger is sucked to contain ozone around the charger. Gas is discharged out of the device through the filter. During the image forming step, the blowing means is set at a low wind speed, and after the image forming step is completed, the blowing means is set at a high wind speed. There is known a device which prevents vibration (for example, see Japanese Patent Application Laid-Open No. 1-26).
No. 3668).

In addition, the conductive shield is electrically grounded via a floating or high resistance during an image forming operation, and is grounded directly or via a low resistance during a period other than the image forming operation. There is also known a device that controls corona wind, performs good charging during operation, and eliminates residual ozone when operation is stopped (for example, see Japanese Patent Application Laid-Open No. 60-189767).

[Problems to be solved by the invention]

However, when the conventional configuration is applied to a multicolor image forming apparatus which collectively transfers a plurality of color toner images formed on an image carrier surface to a transfer material, which has been recently developed, it is difficult to form the image in a previous process. Since the applied toner image area passes through the position of the charger, there is a problem in that the toner image is disturbed by an air current or a corona wind toward the surface of the image carrier during the passage.

In the multicolor image forming apparatus, since the charge is removed from the toner image area formed in the previous process, the toner image is removed by suction from the charger to remove ozone. There is also a problem that the toner in the area is likely to fly and adhere to the main wires and grids of the charger, and the main wires and the like are soiled, thereby causing background stain on the image.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide a multicolor image forming apparatus capable of efficiently removing ozone around a charger without deteriorating image quality. To provide.

[0008]

In order to achieve the above object, a first aspect of the present invention comprises an image carrier, a charger, an optical writing optical device, and a developing device. Multi-color image formation in which a multi-color superimposed toner image is formed on an image carrier surface by repeating an image forming process including each process of charging, image light writing, and development, and the superimposed toner image is collectively transferred to a transfer material In the device, forced ventilation means comprising at least one of blowing means for blowing air from around the charger to the outside and suction means for sucking air from the periphery of the charger to the outside,
When the charger faces the toner image area on the image carrier, the forced ventilation means is not operated.When the charger faces a non-toner image area on the image carrier, the forced ventilation is not applied. And forced ventilation control means for operating the ventilation means.

According to a second aspect of the present invention, there is provided an image carrier, a charging device, an optical writing optical device, and a developing device, and includes charging, image light writing, and developing steps for each color. In a multi-color image forming apparatus that repeats the image forming process to form a multi-colored toner image on the surface of the image carrier and collectively transfers the multi-colored toner image onto a transfer material, air is blown around the charger from outside. A forced air ventilation means comprising at least one of a blowing means and a suction means for sucking air from the periphery of the charger to the outside, and an air flow when the charger faces a toner image area on the surface of the image carrier. And a forced air ventilation control means for operating the forced air ventilation means with a smaller air flow than when the container faces a non-toner image area on the surface of the image carrier.

A third aspect of the present invention includes an image carrier, a charger, an optical writing optical device, and a developing device, and includes charging, image light writing, and developing steps for each color. In a multicolor image forming apparatus that repeats the image forming process to form a multi-color superimposed toner image on the surface of the image carrier and collectively transfers the superimposed toner image to a transfer material, air is blown from the outside to the periphery of the charger. And forced ventilation means for selecting suction from the periphery of the charger to the outside; and selecting the blower when the charger faces a toner image area on the surface of the image carrier; Is provided with a forced ventilation control means for selecting the suction when facing a non-toner image area on the surface of the image carrier.

According to a fourth aspect of the present invention, in the multi-color image forming apparatus according to the third aspect, the air blowing when the charger faces the toner image area on the surface of the image carrier by the forced ventilation control. The air flow of the suction is made smaller than the air flow of the suction when the charger faces the non-toner image area on the surface of the image carrier, and the forced ventilation means is operated.

[0012]

In the first aspect of the present invention, the forced ventilation control means prevents the forced ventilation means from operating when the charger faces the toner image area on the image carrier. This prevents the toner in the toner image area from being attracted to and adhered to the member of the charger.
And to prevent the toner image from being disturbed by the airflow generated by the forced ventilation means.

According to the second aspect of the present invention, when the charger faces the toner image area, the airflow is reduced to activate the forced ventilation means. Thus, when the charger faces the toner image, even if ozone or the like generated by the discharge by the charger easily stays, the ozone or the like is removed.

According to the third aspect of the present invention, when the charger faces the toner image area on the surface of the image carrier, only the blowing is performed. This prevents the toner in the toner image area from being attracted to and adhered to the members of the charger even when the toner image area receives the charge for neutralization and the attraction force is weakened. .

In the invention of claim 4, the amount of air blown when the charger faces the toner image area is reduced. Thereby, even when the toner image area receives the charge for static elimination and the attraction force is weak,
This is to prevent the toner image from being disturbed.

Further, in the invention of claims 1 to 4,
When the charger faces the non-toner image area, ventilation around the charger is performed by the forced ventilation means. Thereby, ozone and the like generated at the time of discharging by the charger can be efficiently removed.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to an electrophotographic copying machine having a full-color mode as a multicolor image forming apparatus (hereinafter referred to as a copying machine) will be described below. FIG. 1 is a schematic configuration diagram of a copying machine according to the present embodiment. First, an outline of the image forming operation in the full-color mode will be described.

In the full-color mode, a yellow (hereinafter referred to as Y) image is written by the laser beam L on the surface of the photosensitive drum 2 uniformly charged to -900 V by the scorotron charger 1, whereby toner adheres. An electrostatic latent image (hereinafter, referred to as a Y latent image) of a negative Y image in which the potential of the image portion, which is a power portion, is lowered is formed. Here, the potential of the image portion has dropped to -100. This Y latent image is reversely developed by a Y developing device 3 provided with negatively charged Y toner to be a Y toner image. The developer employs one non-magnetic component. Then, the transfer unit 7 and the cleaning unit 8 are retracted from the surface of the photosensitive drum 2 at the time of the overlap development, so that the transfer and cleaning are not performed, and the second color image formation (image forming process) is started.

The surface of the photosensitive drum 2 on which the Y toner image is formed is subjected to AC charge removal by the charge remover 12 before cleaning, and is then uniformly charged again to -900 V by the scorotron charger 1, and then the image is formed. A magenta (hereinafter, referred to as M) image is written by laser exposure L with the leading end together with the Y image, and a negative M electrostatic latent image (hereinafter, referred to as M latent image) is formed. This M latent image is a M image provided with a negatively charged M toner without disturbing the first color image due to non-contact.
The image is reversely developed by the developing device 4 to be an M toner image.

Thereafter, similarly, a cyan (hereinafter, referred to as C) toner image and, if necessary, a black (hereinafter, referred to as K) toner image are formed using the C developing device 5 and the K developing device 6.

The superimposed toner image on the surface of the photosensitive drum 2 is sent from the registration roller 9 by applying a positive DC bias to the transfer roller 7a of the transfer unit 7 returned to the normal operation position. Transferred to transfer paper. further,
The sheet is fixed by the fixing device 10 and is discharged by the discharge roller 11. On the other hand, the transfer residual toner on the surface of the photosensitive drum 2 is subjected to the pre-cleaning charge removal by the DC superimposed AC charge by the pre-cleaning charge remover 12, and then the conductive toner of the cleaning unit 8 is returned to the normal operation position. The cleaning is performed by the fur brush 8a.

In the above example, the toner images are formed in the order of Y, M, C and, if necessary, K. However, the present invention is not limited to this, and the toner images may be formed in any predetermined order. The formation may be performed.

The configuration of the scorotron charger 1 is as follows. As shown in FIG. 2 to FIG.
a covers the main wire 1b from three directions, and an opening is provided on the back surface. The grid 1c is formed using a wire, and is connected to have the same potential as the conductive shield 1a. A voltage of about −5 kV is applied to the main wire 1 b by a high-voltage power supply (not shown).
-800 is supplied to the grid 1c by an intermediate voltage power supply (not shown).
About V is applied. In order to remove ozone around the scorotron charger 1, a fan 13 as a forced ventilation means is installed behind the back of the scorotron charger 1 so that air can be blown or sucked toward the scorotron charger 1. It has become. The fan 13 is connected to a fan control unit 14 serving as a forced ventilation control unit, and the fan control unit 14 is configured to control ON / OFF, a rotation speed, a rotation direction, and the like of the fan 13.

In this embodiment, as described above, the toner image area such as the M toner image formed on the surface of the photosensitive drum 2 in the previous step passes through the position of the scorotron charger 1. Therefore, in the first embodiment, when the scorotron charger 1 faces the toner image area on the surface of the photosensitive drum 2 as shown in FIG. 2A, the rotation of the fan 13 is stopped, and as shown in FIG. When the scorotron charger 1 faces an area other than the toner image on the surface of the photosensitive drum 2 (hereinafter, referred to as a non-toner image area), the fan 13 is rotated so that, for example, the scorotron charger 1 sucks the scorotron. , And is controlled by the fan control unit 14. Here, the dashed line with an arrow near the scorotron charger 1 in FIG. 2 schematically shows the direction of the airflow and the magnitude of the airflow, and the same applies to FIGS. 3 to 5 hereinafter. FIG. 3 shows a timing chart of ON / OFF of each device of the copying machine in the present embodiment. ON / OFF of the fan 13 in the first embodiment is
This is performed at the timing indicated by the bottom line in FIG.

As described above, according to the first embodiment, when the scorotron charger 1 faces the toner image area, the rotation of the fan 13 is stopped, and the suction from the scorotron charger 1 is stopped. Of the toner on the main wire 1b and the grid 1c of the scorotron charger 1 does not adhere. As a result, abnormalities in the image such as background contamination do not appear. Further, when the scorotron charger 1 faces the non-toner image area, the fan 13 is operated to suck the scorotron from the scorotron charger 1, so that ozone and the like generated during the discharge can be removed. This allows
Deterioration of the photoconductor on the surface of the photoconductor drum 2 due to ozone or the like can be prevented.

Next, a second embodiment will be described. The basic configuration of the copying machine is the same as that of the first embodiment, and a description of those functions will be omitted. In the first embodiment, when the scorotron charger 1 faces the toner image area on the surface of the photosensitive drum 2 as shown in FIG. 2A, the operation of the fan 13 is completely stopped. Ozone and the like may stay around the vessel 1. Therefore, in the second embodiment, instead of controlling the stop / actuation of the blowing or suction by the fan 13, the scorotron charger 1 faces the toner image area on the surface of the photosensitive drum 2 as shown in FIG. At this time, the rotation of the fan 13 is slowed and the suction from the scorotron charger 1 is weakened.
As shown in (b), the scorotron charger 1 is connected to the photosensitive drum 2
When facing the non-toner image area on the surface, the fan control unit 14 controls the rotation speed of the fan 13 so that the rotation of the fan 13 is accelerated and the suction from the scorotron charger 1 is increased.

As described above, according to the second embodiment, even when the scorotron charger 1 faces the toner image area, the fan 13
Since the rotation of the roller is slowed and the weak suction from the scorotron charger 1 is performed, there is no possibility that ozone or the like stays around the scorotron charger 1.

In the first and second embodiments, the fan 1 is so drawn as to be sucked from the scorotron charger 1.
Although the fan 3 is rotated, the fan 13 may be rotated so as to blow air to the scorotron charger 1. In this case, when the scorotron charger 1 faces the toner image area on the surface of the photosensitive drum 2, the blowing is stopped or the blowing is reduced, so that the toner image is not disturbed.

Next, a third embodiment will be described. The basic configuration of the copying machine is the same as that of the first embodiment, and a description of those functions will be omitted. As described above, an AC charge is removed from the toner image formed on the surface of the photosensitive drum 2 by the pre-cleaning charge remover 12 before charging the next color. The AC charge removal is necessary to suppress an increase in toner charge when receiving the next color charge. Then, the charge amount of the toner that has been subjected to the AC neutralization charge becomes substantially zero, and the attraction force with the surface of the photosensitive drum 2 decreases. Therefore, there arises a problem that the toner in the toner image area that has been subjected to the AC charge removal is attracted to the main wire 1b and the grid 1c of the scorotron charger 1 and is likely to adhere thereto. Since the toner image area does not face the scorotron charger 1 unless it is the overlap development method, this problem can be said to be peculiar to the overlap development method.

Therefore, in the third embodiment, when the scorotron charger 1 faces the toner image area on the surface of the photosensitive drum 2 as shown in FIG. When the scorotron charger 1 faces the non-toner image area on the surface of the photosensitive drum 2 as shown in FIG. 5B, the suction from the scorotron charger 1 is performed.
The rotation direction of the fan 13 is controlled by the fan control unit 14. In addition, ON / OF of the fan 13 in the third embodiment.
F is performed at the timing indicated by the second line from the bottom in FIG.

As described above, according to the third embodiment, when the scorotron charger 1 faces the toner image area, air is blown to the scorotron charger 1, so that the toner image area receives the AC charge removal charge. Even if it is, the toner in the toner image area will not be attracted to and adhered to the main wire or grid of the scorotron charger 1. As a result, abnormalities in the image such as background contamination do not appear. Further, when the scorotron charger 1 faces the non-toner image area, the scorotron charger 1 sucks the ozone and the like, so that ozone and the like generated at the time of discharge can be removed. Thereby, deterioration of the photoconductor on the surface of the photoconductor drum 2 due to ozone or the like can be prevented.

Next, a fourth embodiment will be described. The basic configuration of the copying machine is the same as that of the first embodiment, and a description of those functions will be omitted. In the third embodiment, when the scorotron charger 1 faces the toner image area on the surface of the photosensitive drum 2, air is blown to the scorotron charger 1, so that the toner image is disturbed by the blow. There is fear. Therefore, in the fourth embodiment, FIG.
(A) As shown in FIG.
When facing the toner image area on the surface, the air is blown to the scorotron charger 1 and the rotation of the fan 13 is slowed down so that the blow is weakened.
When the scorotron charger 1 faces the non-toner image area on the surface of the photosensitive drum 2 as shown in FIG. 6B, suction is performed from the scorotron charger 1 and the fan 1
The fan control unit 14 controls the rotation direction and the rotation speed of the fan 13 so that the rotation of the fan 3 is accelerated to increase the suction.

As described above, according to the fourth embodiment, when the scorotron charger 1 faces the toner image area, the air is weakly blown to the scorotron charger 1, so that the toner image area is subjected to AC charge elimination. Even when the toner is charged, the toner in the toner image area is supplied to the scorotron charger 1
And the toner image is not disturbed. As a result, abnormalities in the image such as background contamination do not appear. Further, when the scorotron charger 1 faces the non-toner image area, the scorotron charger 1 sucks the ozone and the like, so that ozone and the like generated at the time of discharge can be removed. Thereby, deterioration of the photoconductor on the surface of the photoconductor drum 2 due to ozone or the like can be prevented.

In the above embodiment, one fan 13
Is used, but a plurality of fans may be used. Further, the ventilation and the suction may be separately assigned to these plurality of fans. The same operation and effect as described above can be obtained even if ventilation means other than a fan is used.

[0035]

According to the first aspect of the present invention, the toner in the toner image area is not attracted to and adhered to the member of the charger, and the toner image is not disturbed. There is an excellent effect that the abnormality of the image does not appear.

According to the second aspect of the present invention, even when ozone and the like generated by the discharge of the charger tend to stay when the charger faces the toner image, the ozone and the like are removed. Therefore, there is an excellent effect that deterioration of the photoreceptor on the surface of the image carrier due to the ozone or the like can be prevented.

According to the third aspect of the present invention, even when the toner image area is subjected to the charge removal and the attraction force is weakened, the toner in the toner image area remains on the member of the charger. Since the ink is not attracted and adhered, there is an excellent effect that abnormalities in the image such as background contamination do not appear.

According to the fourth aspect of the present invention, even when the toner image area receives the charge for neutralization and the attraction force is weakened, the toner image is not disturbed. There is an excellent effect that the abnormalities of the image such as the above do not appear.

According to the first to fourth aspects of the present invention, ozone and the like generated at the time of discharging by the charger can be efficiently removed. There is also an excellent effect that deterioration of the photoconductor can be prevented.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a copying machine according to an embodiment.

FIG. 2A is a diagram illustrating forced ventilation in a toner image area according to a first embodiment, and FIG. 2B is a diagram illustrating forced ventilation in a non-toner image region according to the first embodiment.

FIG. 3 is a timing chart of the operation of each device of the copying machine according to the embodiment.

FIG. 4A is an explanatory view of forced ventilation in a toner image area according to a second embodiment, and FIG. 4B is an explanatory view of forced ventilation in a non-toner image area according to the second embodiment.

FIG. 5A is an explanatory view of forced ventilation in a toner image area according to a third embodiment, and FIG. 5B is an explanatory view of forced ventilation in a non-toner image area according to the third embodiment.

FIG. 6A is an explanatory view of forced ventilation in a toner image area according to a fourth embodiment, and FIG. 6B is an explanatory view of forced ventilation in a non-toner image area according to the fourth embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Scorotron charger 1a Shield 1b Main wire 1c Grid 2 Photoreceptor drum 3 Y developing device 4 M developing device 5 C developing device 6 K developing device 12 Static electricity remover before cleaning 13 Fan 14 Fan control unit

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G03G 15/02 G03G 15/01 G03G 21/00 538

Claims (4)

(57) [Claims] An image forming process including an image carrier, a charging device, an optical writing optical device, and a developing device, and for each color, repeating an image forming process including charging, image light writing, and developing processes.
A multicolor image forming apparatus for forming a plurality of superimposed toner images on the surface of the image carrier and transferring the superimposed toner images to a transfer material at a time; Forced ventilation means comprising at least one of suction means for sucking from the periphery to the outside; and when the charger faces the toner image area on the surface of the image carrier, the forced ventilation means is not operated, and And a forced-ventilation control means for activating the forced-ventilation means when the container faces a non-toner image area on the surface of the image carrier. 2. An image forming process comprising an image carrier, a charger, an optical writing optical device, and a developing device, and repeating an image forming process including charging, image light writing, and developing processes for each color,
A multicolor image forming apparatus for forming a plurality of superimposed toner images on the surface of the image carrier and transferring the superimposed toner images to a transfer material at a time; A forced ventilation means comprising at least one of suction means for sucking from the periphery to the outside, and a flow rate when the charger faces the toner image area on the image carrier surface. And a forced air ventilation control means for operating the forced air ventilation means with a flow rate smaller than the air flow when facing the non-toner image area. 3. An image forming process including an image carrier, a charger, an optical writing optical device, and a developing device, and repeating an image forming process including charging, image light writing, and developing processes for each color,
In a multicolor image forming apparatus for forming a plurality of superimposed toner images on the surface of an image carrier and simultaneously transferring the superimposed toner images to a transfer material, air is blown from the outside to the periphery of the charger, and the periphery of the charger is And forced ventilation means that can select suction from the outside to the outside, and when the charger faces the toner image area on the image carrier surface, selects the air blowing, and the charger operates on the image carrier surface. A multicolor image forming apparatus, comprising: a forced ventilation control unit that selects the suction when facing a non-toner image area. 4. A flow rate of the air blown when the charger faces the toner image area on the surface of the image carrier by the forced ventilation control, and the air flow rate of the non-toner image on the surface of the image carrier is controlled by the charger. 4. The multicolor image forming apparatus according to claim 3, wherein said forced ventilation means is operated by reducing a flow rate of the suction air when facing the area.