JP2001166614A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device capable of removing a detecting pattern on which a transfer bias voltage for transferring to a transfer material is not applied without being stuck to an intermediate transfer body again. SOLUTION: The image forming device is provided with toner image forming means 2, 3 and 4, a toner concentration detecting means 5, the intermediate transfer body 11, a primary transfer member 12, a primary transfer bias voltage applying means 13a, a secondary transfer member 31, a secondary transfer bias voltage applying means 32 and a control means 81 for controlling the operation of each means. The primary transfer bias voltage applying means 13a can apply the voltage whose polarity is opposite to that of the toner and also the voltage whose polarity is the same as that of the toner. The control means 81 can form the detecting pattern 61 on the image carrier 11 other than a position transferred to the transfer material 51 by using the toner image forming means 2, 3 and 4, and can control, the primary transfer bias voltage applying means 13a so that the voltage whose polarity is opposite to that of the toner is applied when the toner image 71 formed on the image carrier 11 exists in a primary transfer position 91, besides the voltage whose polarity is the same as that of the toner is applied when the detecting pattern 61 exists in the primary transfer position 91.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus for forming an image by an electrophotographic method, such as a laser printer or a copying machine, and more particularly, to a method for transferring a toner image to a transfer paper or the like using an intermediate transfer member. Image forming method,
The present invention relates to an image forming apparatus having a configuration for reliably removing a density detection pattern formed on an image carrier.

[0002]

2. Description of the Related Art In an electrophotographic image forming apparatus, a toner image formed on an image carrier (photoreceptor) is transferred onto a transfer material such as transfer paper, and the toner image on the transfer material is fixed. To form an image. In recent years, color image forming apparatuses such as color printers and color copiers generally use an intermediate transfer member, and the toner image on the image carrier is temporarily transferred to the intermediate transfer member, After the toner image on the transfer member is transferred onto the transfer material, the toner image is fixed. Further, in the color image forming apparatus, in order to detect the density of each color toner adhered on the image carrier to form a toner image, the position of the transfer image area 92 on the image carrier (the transfer image A toner density detection pattern (hereinafter, referred to as a detection pattern) is formed at the rear position). Then, the detection pattern formed on the image carrier is converted to a toner density detection unit (hereinafter, referred to as a toner density detector) installed near the surface of the image carrier.
The density of the toner image is detected by detecting the density of the toner image. By the way, the detection pattern formed outside the transfer area on the image carrier becomes unnecessary after the density is detected by the detection means, and if left as it is, it adversely affects the next image forming process. There is a need to. Hereinafter, a configuration of a conventional image forming apparatus using an intermediate transfer body and an operation of removing a detection pattern will be described with reference to the drawings. FIG. 5 is a side view showing a schematic configuration of a conventional image forming apparatus using an intermediate transfer member. The image carrier 1 has a drum shape with a photosensitive layer formed on the outer peripheral surface,
A toner image is formed on the surface, carried and rotated in the direction of →. The charging unit 2 charges the photosensitive layer on the surface of the image carrier 1 to a uniform polarity. The optical writing unit 3 writes an electrostatic latent image on the previously charged image carrier 1 using optical image information such as laser light. When the detection pattern 61 is formed on the image carrier 1, an electrostatic latent image for the detection pattern 61 is also written on the image carrier 1 when writing with a laser beam or the like. The developing device 4 develops the electrostatic latent image on the image carrier 1 using toner to form a toner image 71 and a detection pattern 61. When a full-color image is formed by the color image forming apparatus, four color toners of cyan (C), magenta (M), yellow (Y), and black (K) are sequentially supplied from the developing device 4. The toner density detector 5 (toner density detector) is, for example, an optical sensor or the like, and detects the density of the detection pattern 61 formed on the image carrier 1. Detection pattern 61 formed on image carrier 1
Is transferred together with the toner image 71 at the primary transfer position 91 onto the intermediate transfer body 11 formed of an elastic belt or the like. The image carrier cleaning device 6 is, for example, a spatula made of an elastic dielectric such as rubber. One end of the cleaning device 6 is in contact with the surface of the image carrier 1. After the image 71 is transferred, the residual toner remaining on the image carrier 1 is removed.

The primary transfer member 12 is, for example, a roller-shaped transfer means. The primary transfer member 12 presses the intermediate transfer member 11 against the image carrier 1 at a primary transfer position 91, and also a toner image 71 on the image carrier 1 and a detection pattern. A primary transfer bias voltage is applied to 61. Primary transfer bias voltage applying device 1
3 (primary transfer bias voltage applying means) supplies a primary transfer bias voltage to the primary transfer member 12. The bias voltage for the primary transfer is a voltage having a polarity opposite to a charging voltage of the toner image on the image carrier, and becomes a positive voltage when the toner image is charged to a negative voltage. When the primary transfer voltage is applied to the toner image 71 and the detection pattern 61 on the image carrier 1, the toner image 71 and the detection pattern 61 are transferred onto the intermediate transfer body 11. Drive roller 1
Reference numerals 4, 15, and 16 each have a roller shape, and rotate the intermediate transfer body 11 by transmitting power from a motor or the like to at least one of the driving rollers 14, 15, and 16. . The detection pattern 61 transferred onto the intermediate transfer body 11 is transferred onto the transfer material 51 such as transfer paper at a secondary transfer position 92 together with the toner image 71. The intermediate transfer member cleaning device 17 is, for example, a spatula-shaped elastic dielectric such as rubber. One end of the cleaning device 17 is in contact with the surface of the intermediate transfer member 11.
After the toner image 71 is transferred, the detection pattern 61 remaining on the image carrier 1 and the remaining toner of the toner image 71 are removed. Intermediate transfer body cleaning device contact / separation device 2
0 designates the intermediate transfer member cleaning device 17 as the intermediate transfer member 1
1. For example, in a color image forming apparatus, four color toner images of cyan (C), magenta (M), yellow (Y), and black (K) are transferred to an intermediate transfer member. When the image is superimposed on the intermediate transfer body 11, the intermediate transfer body cleaning device 17 is separated from the intermediate transfer body 11 until all the colors are superimposed and the secondary transfer is completed.

The secondary transfer member 31 is, for example, a roller-shaped transfer means.
1 is pressed against the intermediate transfer body 11 and the intermediate transfer body 1
A secondary transfer bias voltage is applied to the upper toner image 71. The secondary transfer bias voltage applying device 32 (secondary transfer bias voltage applying unit) supplies a secondary transfer bias voltage to the secondary transfer member 31. The bias voltage for the secondary transfer is also a voltage having a polarity opposite to the charging voltage of the toner image similarly to the bias voltage for the primary transfer, and becomes a positive voltage when the toner image is charged to a negative voltage, for example. . When the secondary transfer voltage is applied to the toner image 71 on the intermediate transfer body 11, the toner image 71 is transferred onto the transfer material 51. The secondary transfer member contact / separation device 34 (secondary transfer member contact / separation means) is a device capable of moving the secondary transfer member 31 toward and away from the intermediate transfer member 11. After the transfer of the toner image 71 on the transfer material 51 onto the transfer material 51 is completed,
Before the detection pattern 61 on the intermediate transfer member 11 reaches the secondary transfer position 92, the secondary transfer member 31 is moved to the intermediate transfer member 1.
It is a device that is separated from 1. The separation unit 35 separates the transfer material 51 from the intermediate transfer body 11 by applying a voltage for separation to the transfer material 51 onto which the toner image 71 has been transferred. The fixing unit 36 fixes the toner image 71 on the transfer material 51 by applying pressure while heating with a heater or the like, for example. The transfer material 51 on which the toner image 71 is fixed is discharged out of the image forming apparatus. The control unit 81 includes, for example, a microprocessor or the like, and controls an image forming process or an operation timing of each of the units and each device. next,
An operation of removing a detection pattern in a conventional example will be described. Charging unit 2, optical writing unit 3, and developing device 4
The detection pattern 61 formed on the image carrier 1 by the toner image forming means is transferred to the intermediate transfer body 11 at the primary transfer position 91. The detection pattern 61 transferred onto the intermediate transfer body 11 is
6, the intermediate transfer body 11 is moved by rotating. The detection pattern 61 on the intermediate transfer body 11
When the secondary transfer member 31 reaches the secondary transfer position 92, it passes through the secondary transfer position 92 because the secondary transfer member 31 is in contact with or separated by the secondary transfer member contact / separation device 34. Secondary transfer position 9
2 for the detection pattern 61 on the intermediate transfer body 11
Is removed by the intermediate transfer member cleaning device 17. That is, when the secondary transfer member 31 and the toner image 71 on the intermediate transfer member 11 come into contact with each other, the controller 81 (control means) controls the intermediate transfer member 1 by the secondary transfer member contact / separation device 34.
1 and the secondary transfer member 31 are brought into contact with each other.
The secondary transfer member contact / separation device 34 before the intermediate transfer member 11 contacts the detection pattern 61 on the intermediate transfer member 11.
The secondary transfer member 31 is brought into contact with and separated from. In the case of a color image forming apparatus, the toner image 71 where each color overlaps is passed,
The intermediate transfer member cleaning device 17 is moved by the intermediate transfer member cleaning device contact / separation device 20 so that the detection pattern 61 for each color is removed. The above processing is performed by the control unit 81
This is carried out in accordance with instructions to each unit and each device.

FIG. 6 is a view of the position of the detection pattern 61 formed on the image carrier 1 as viewed from below. As shown in FIG. 6, a toner image 71 and a detection pattern 61 are formed on the image carrier 1 using a toner image forming unit. The toner image 71 is formed at a position (range) on the image carrier 1 to be transferred to the transfer material 51, and the detection pattern 61 is formed on the transfer material 5.
No. 1 is formed at the rear position (outside the transfer image area 92) that is not transferred. FIG. 7 is a view of the positions of the toner image 71 and the detection pattern 61 transferred onto the intermediate transfer member 11 as viewed from below. As shown in FIG. 7, a toner image 71 and a detection pattern 61 are transferred onto the intermediate transfer body 11. The toner image 71 in FIG. 7 is transferred to the transfer material 51 at the secondary transfer position 92 because the secondary transfer member 31 applies a transfer bias while pressing the transfer material 51 against the intermediate transfer body 11.
On the other hand, the detection pattern 61 of FIG.
Is in contact with or separated from the transfer material 51, so that the secondary transfer position 92
Pass through the intermediate transfer body 11 while being transferred. Thus, the toner image 71 on the intermediate transfer material 11 is transferred to the transfer material 51, and the detection pattern 61 on the intermediate transfer material 11 is removed by the intermediate transfer body cleaning device 17.

[0006]

However, the detection pattern 61 on the intermediate transfer material 11 is located at the secondary transfer position 92.
Since the secondary transfer bias is not applied from the secondary transfer member 31, the toner image 71 on the intermediate transfer material 11
Is different from the residual toner remaining on the intermediate transfer material 11 after being transferred onto the transfer material 51 in electrical characteristics (charge potential). Further, a primary transfer bias is applied to the intermediate transfer member 11 from the primary transfer member 12 at the primary transfer position 91, and a secondary transfer bias is applied from the secondary transfer member 31 at the secondary transfer position 92. The intermediate transfer body 11 itself is also charged. Further, in the color image forming apparatus, as described above, the intermediate transfer body cleaning device contact / separation device 20 is used.
Accordingly, the intermediate transfer body cleaning device 17 is brought into contact with or separated from the intermediate transfer body 11. Here, the detection pattern 61 on the intermediate transfer member 11 is removed by the intermediate transfer member cleaning device 17, and thereafter, the intermediate transfer member cleaning device 17 is separated from the intermediate transfer member 11 by the intermediate transfer member cleaning device contacting / separating device 20. It comes and goes. Further, a part of the toner removed from the detection pattern 61 adheres to the intermediate transfer body cleaning device 17. Since the secondary transfer bias is not applied to the toner attached to the intermediate transfer body cleaning device 17,
The charge that has been transferred onto the intermediate transfer body 11 is held as it is. Therefore, when the intermediate transfer member cleaning device 17 is brought into contact with or separated from the intermediate transfer member 11, a part of the toner attached to the intermediate transfer member cleaning device 17 is sucked by the charging voltage of the intermediate transfer member, and is again transferred to the intermediate transfer member. It may adhere to the body 11. In this way, the toner re-adhering to the intermediate transfer body 11 causes an inconvenience of adhering to the toner image 71 or the like and causing image contamination. The problem that the toner used for the detection pattern 61 on the intermediate transfer member 11 adheres again to the intermediate transfer member 11 is not considered at all in the conventional image forming apparatus. Japanese Patent Application Laid-Open No. 9-44007 discloses a method in which residual toner after transferring a toner image (to which a transfer bias voltage is applied) is reverse-transferred to an image bearing member. Is not for a detection pattern to which no transfer bias voltage is applied. The present invention has been made in order to solve the conventional problems as described above, and it is possible to remove a detection pattern to which a transfer bias voltage for transferring to a transfer material is not applied without re-adhering to an intermediate transfer body. It is an object to provide an image forming apparatus.

[0007]

According to another aspect of the present invention, there is provided an image forming apparatus, comprising: a toner image forming unit for forming a toner image on an image carrier; A toner density detecting means for detecting the density of the toner image formed thereon, and an intermediate for contacting the image carrier at the primary transfer position and receiving the transfer of the toner image and then moving the toner image to the secondary transfer position A transfer member, a primary transfer member for transferring a toner image formed on the image carrier onto the intermediate transfer member at a primary transfer position, and a primary transfer bias for supplying a bias voltage having a polarity opposite to that of the toner image to the primary transfer member Voltage applying means, a secondary transfer member for transferring the toner image transferred on the intermediate transfer member to a transfer material at a secondary transfer position, and a bias voltage having a polarity opposite to that of the toner image to the secondary transfer member. Next transfer bias voltage Application means, and control means for controlling the operation of each means, wherein the control means uses the toner image forming means to apply a toner density detection pattern to a position outside the transfer image area on the image carrier. In the image forming apparatus that controls formation, the primary transfer bias voltage applying unit may generate a voltage having the same polarity as the toner image in addition to a voltage having a polarity opposite to the polarity of the toner image on the image carrier. Can,
When the toner image formed on the image carrier is at the primary transfer position, the control unit generates a voltage having a polarity opposite to the polarity of the toner image from the primary transfer bias voltage applying unit,
When the toner density detecting pattern is at the primary transfer position, a voltage having the same polarity as the polarity of the toner is applied from the primary transfer bias voltage applying means. An image forming apparatus according to a second aspect of the present invention includes a toner image forming unit that forms a toner image on an image carrier, and a toner density detecting unit that detects the density of the toner image formed on the image carrier. An intermediate transfer member that contacts the image carrier at the primary transfer position and receives the transfer of the toner image, and then moves the toner image to the secondary transfer position; and a primary transfer of the toner image formed on the image carrier. A primary transfer member for transferring the toner image onto the intermediate transfer member at a position; a primary transfer bias voltage applying unit for supplying a bias voltage having a polarity opposite to that of the toner image to the primary transfer member; A secondary transfer member for transferring to a transfer material at a next transfer position, a secondary transfer bias voltage applying unit for supplying a bias voltage having a polarity opposite to that of the toner image to the secondary transfer member, and a control for controlling the operation of each unit Means and In the image forming apparatus, the control unit controls the formation of the toner density detection pattern at a position outside the transfer image area on the image carrier using the toner image forming unit. A primary transfer member contacting / separating unit that can freely contact / separate from the control unit, and the control unit includes:
When the toner image formed on the image carrier is at the primary transfer position, the primary transfer member is brought into contact with the image carrier by the primary transfer member contacting / separating means, and when the toner density detection pattern is at the primary transfer position. The primary transfer member is separated from the image carrier by the primary transfer member contacting / separating means.

According to a third aspect of the present invention, there is provided an image forming apparatus for forming a toner image on an image carrier, and a toner density for detecting a density of the toner image formed on the image carrier. Detecting means, an intermediate transfer member that contacts the image carrier at the primary transfer position, receives the transfer of the toner image, and moves the toner image to the secondary transfer position, and a toner image formed on the image carrier. A primary transfer member that transfers the toner image onto the intermediate transfer member at a primary transfer position, a primary transfer bias voltage applying unit that supplies a bias voltage having a polarity opposite to that of the toner image to the primary transfer member, and a toner that is transferred onto the intermediate transfer member. A secondary transfer member for transferring an image to a transfer material at a secondary transfer position,
A secondary transfer bias voltage applying unit configured to supply a bias voltage having a polarity opposite to that of the toner image to the secondary transfer member; and a control unit configured to control an operation of each unit. Removing the toner density detection pattern transferred onto the secondary transfer member in the image forming apparatus which controls the formation of the toner density detection pattern at a position outside the transfer image area on the image carrier using the means A secondary transfer member cleaning unit; and a secondary transfer member contacting / separating unit for allowing the secondary transfer member to come into and out of contact with the intermediate transfer member. The control unit includes a secondary transfer member and an intermediate transfer member. When the above-mentioned toner density detecting pattern comes into contact with the secondary transfer member, the secondary transfer member is not separated from the intermediate transfer member by the secondary transfer member contacting / separating means, so that the toner density detecting pattern is formed on the secondary transfer member. Turn It is allowed, and removing the toner density detection pattern on the secondary transfer member by the secondary transfer member cleaning means.

According to a fourth aspect of the present invention, there is provided an image forming apparatus, comprising: a toner image forming means for forming a toner image on an image carrier; and a toner density detecting a density of the toner image formed on the image carrier. Detecting means, an intermediate transfer member that contacts the image carrier at the primary transfer position, receives the transfer of the toner image, and moves the toner image to the secondary transfer position, and a toner image formed on the image carrier. A primary transfer member that transfers the toner image onto the intermediate transfer member at a primary transfer position, a primary transfer bias voltage applying unit that supplies a bias voltage having a polarity opposite to that of the toner image to the primary transfer member, and a toner transferred on the intermediate transfer member. A secondary transfer member for transferring an image to a transfer material at a secondary transfer position,
A secondary transfer bias voltage applying unit configured to supply a bias voltage having a polarity opposite to that of the toner image to the secondary transfer member; and a control unit configured to control an operation of each unit. An image forming apparatus that controls the formation of a toner density detection pattern at a position outside a transfer image area on an image carrier using a unit. Transfer member contacting / separating means,
Cleaning bias voltage applying means for supplying a bias voltage having a polarity opposite to that of toner to the toner density detection pattern transferred to the intermediate transfer member, and an intermediate transfer member cleaning device for removing the toner density detection pattern transferred to the intermediate transfer member Wherein the control means contacts the intermediate transfer member and the secondary transfer member by the secondary transfer member contacting / separating means when the secondary transfer member contacts the toner image on the intermediate transfer member. Before the secondary transfer member comes into contact with the toner density detecting pattern on the intermediate transfer member, the secondary transfer member is separated from the intermediate transfer member by the secondary transfer member contacting / separating means, and a cleaning bias is applied. By supplying a bias voltage from the voltage application unit to the toner density detection pattern on the intermediate transfer member, the toner density detection And removing by Utsushitai cleaning means. According to a fifth aspect of the present invention, in the image forming apparatus according to the fourth aspect, the cleaning bias voltage applying means for supplying a bias voltage to the toner density detection pattern is provided between the intermediate transfer body cleaning device and the intermediate transfer body. It is characterized in that a bias voltage is supplied to driving rollers installed at opposing positions.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described based on illustrated embodiments. FIG. 1 is a side view illustrating a schematic configuration of the image forming apparatus according to the first embodiment of the present invention. In FIGS. 1 to 4, parts having the same functions as those of the conventional image forming apparatus shown in FIG. 5 are denoted by the same reference numerals, and redundant description will be omitted. The primary transfer bias voltage applying device 13a used in the image forming apparatus of the present embodiment is a density detection pattern 6 formed on the image carrier 11 from the primary transfer bias voltage applying device 13 via the primary transfer member 12.
1; that is, a voltage having a polarity opposite to the charging polarity of the toner image forming the density detection pattern 61 on the image carrier 11, and the toner used for the density detection pattern 61. And a voltage having the same polarity as the charging polarity can be generated. When the toner image 71 formed on the image carrier 1 is at the primary transfer position 91, the control section 81 (control means) of the present embodiment transmits the toner image 71 to the primary transfer bias voltage applying device 13a (primary transfer bias voltage applying means). On the other hand, it outputs an instruction to apply a voltage having a polarity opposite to the charging polarity of the toner used for the toner image 71, and when the detection pattern 61 is at the primary transfer position 91, the primary transfer bias voltage applying device 13a , An instruction to apply a voltage having the same polarity as the polarity of the toner used in the detection pattern 61 is output. In this embodiment,
For the toner image 71 on the image carrier 1, the intermediate transfer member 1
1, the density detection pattern 61 is not transferred to the intermediate transfer member 11 and passes through the primary transfer position 91 as it is formed on the image carrier 1. Primary transfer position 91 while being formed on image carrier 1
Is removed by the image carrier cleaning device 6. Therefore, since the density detection pattern 61 does not reach the secondary transfer position 92, the toner removed from the density detection pattern 61 does not adhere to the intermediate transfer body cleaning device 17, and is transferred to the transfer material 51. Pattern 61 to which no secondary transfer bias voltage is applied can be removed from the intermediate transfer body cleaning device 17 without re-adhering to the intermediate transfer body 11.

FIG. 2 is a side view showing a schematic configuration of an image forming apparatus according to a second embodiment of the present invention. The primary transfer member 12 used in the image forming apparatus of the present embodiment and the roller 21 that presses the intermediate transfer member 11 to the image carrier 1 accompanying the primary transfer member 12 are moved by the primary transfer member contacting / separating device 18 to the primary transfer position. Can be moved toward and away from.
That is, the primary transfer member contact / separation device 18 is a device that can move the primary transfer member 12 and the roller 21 attached to the primary transfer member 12 so that the intermediate transfer member 11 can be brought into contact with or separated from the image carrier 1. is there. The control unit 81 (control means) of the present embodiment includes a primary transfer member contacting / separating device between the time when the toner image 71 formed on the image carrier 11 starts passing through the primary transfer position 91 and the time when the passage is completed. 18 (primary transfer member contacting / separating unit) to output an instruction to bring the intermediate transfer member 11 into contact with the image carrier 1,
During a period from when the sheet 1 enters the primary transfer position 91 to when the sheet 1 exits, the intermediate transfer member 11 is moved toward and away from the image carrier 1 with respect to the primary transfer member contacting / separating device 18 (primary transfer member contacting / separating means). Output instructions. Also in the present embodiment, the first
Similarly to the embodiment, the toner image 71 on the image carrier 1 can be transferred to the intermediate transfer member 11, while the density detection pattern 61 can be transferred to the intermediate transfer member 1.
1 and is passed through the primary transfer position 91 while being formed on the image carrier 1. Density detection pattern 6 that has passed primary transfer position 91 while being formed on image carrier 1
1 is removed by the image carrier cleaning device 6.
Therefore, since the density detection pattern 61 does not reach the secondary transfer position 92, the toner removed from the density detection pattern 61 does not adhere to the intermediate transfer body cleaning device 17, and is transferred to the transfer material 51. Pattern 61 to which no secondary transfer bias voltage is applied can be removed from the intermediate transfer body cleaning device 17 without re-adhering to the intermediate transfer body 11.

FIG. 3 is a side view showing a schematic configuration of an image forming apparatus according to a third embodiment of the present invention. The secondary transfer member 31 used in the image forming apparatus of the present embodiment includes a secondary transfer member cleaning device 33. The secondary transfer member cleaning device 33 is, for example, a spatula-shaped elastic dielectric such as rubber. One end of the cleaning device 33 is in contact with the surface of the secondary transfer member 31, and is transferred onto the secondary transfer member 31. The detected pattern 61 is removed. The control unit 81 (control means) of the present embodiment controls the toner image 7 on the intermediate transfer body 11.
When the secondary transfer member 31 and the detection pattern 61 on the intermediate transfer body 11 contact each other at the secondary transfer position 92 after the transfer of the first transfer member 1 to the transfer material 51, the secondary transfer member contact / separation device 34 To the secondary transfer member 31 so that the secondary transfer member 31 is not brought into contact with or separated from the intermediate transfer member 11. In this embodiment,
For the toner image 71 on the intermediate transfer body 11, the transfer material 5
1, while the density detection pattern 61 is transferred onto the secondary transfer member 31 and removed by the secondary transfer member cleaning device 33. Therefore, since the density detection pattern 61 does not reach the intermediate transfer body cleaning device 17, the toner removed from the density detection pattern 61 does not adhere to the intermediate transfer body cleaning device 17.
The detection pattern 61 to which the secondary transfer bias voltage for transferring to the intermediate transfer member 11 is not applied can be removed without reattaching to the intermediate transfer body 11. Further, in the present embodiment, a primary bias voltage application device capable of applying a voltage of the same polarity in addition to the voltage of the opposite polarity to the toner of the first embodiment, and a primary transfer member contacting / separating member of the second embodiment. Since no device is required, the image forming apparatus can be configured at low cost.

FIG. 4 is a side view showing a schematic configuration of an image forming apparatus according to a fourth embodiment of the present invention. A cleaning bias voltage applying device 19 (cleaning bias voltage applying means) is connected to the drive roller 16 used in the image forming apparatus of the present embodiment. The driving roller 16 is
Intermediate transfer member cleaning device 1 with intermediate transfer member 11 interposed
7 is a roller installed at a position opposite to 7. The cleaning bias voltage applying device 19 supplies the driving roller 16 with a cleaning bias voltage having the same polarity as the secondary transfer bias voltage applied to the secondary transfer member 31. The cleaning bias voltage is also a voltage of the opposite polarity to the toner charging voltage, like the primary transfer bias voltage and the secondary transfer bias voltage.For example, when the toner is charged to a negative voltage, the cleaning bias voltage is a positive voltage. Become. When the cleaning bias voltage is applied to the density detection pattern 61, the charge of the density detection pattern 61 on the intermediate transfer body 11 is changed to the residual toner after the transfer of the toner image 71 on the intermediate transfer body 11. The potential becomes the same, and after the toner is removed by the intermediate transfer member cleaning device 17, it is not transferred again to the intermediate transfer member 11. Control unit 81 of the present embodiment
When the secondary transfer member 31 and the toner image 71 on the intermediate transfer member 11 come into contact with each other, the control unit controls the secondary transfer member contacting / separating device, similarly to the conventional image forming apparatus shown in FIG. The intermediate transfer body 11 and the secondary transfer member 31 are brought into contact with each other by 34,
Before the secondary transfer member 31 and the detection pattern 61 on the intermediate transfer body 11 come into contact with each other, the secondary transfer member 31 is brought into contact with and separated from the intermediate transfer body 11 by the secondary transfer member contact / separation device 34, and the intermediate transfer After the residual toner of the toner image 71 on the body 11 is removed by the intermediate transfer body cleaning device 17, the cleaning bias voltage is applied before the detection pattern 61 on the intermediate transfer body 11 reaches the intermediate transfer body cleaning device 17. An instruction is supplied to the application device 19 to supply the cleaning bias voltage to the drive roller 16.

In the present embodiment, the toner image 71 on the intermediate transfer member 11 is removed by the intermediate transfer member cleaning device 17 as it is, while the density detection pattern 6 is removed.
As for No. 1, the cleaning bias voltage is applied to prevent the toner from re-adhering onto the intermediate transfer member 11 and then removed by the intermediate transfer member cleaning device 17. Further, as the applied voltage of the cleaning bias voltage applying device 19,
Since a voltage having the same polarity as that of the secondary transfer bias voltage applying device 32 is applied, the secondary transfer bias voltage applying device 3
2 may be used by switching.
Therefore, the density detection pattern 61 is
Since the charging potential when the cleaning bias voltage is applied is changed from the charging potential when the transfer is performed on
The charging potential of the toner removed from the density detection pattern 61 attached to the intermediate transfer body cleaning device 17 also becomes the charging potential when the cleaning bias voltage is applied.
For this reason, a cleaning bias voltage similar to the secondary transfer bias voltage is applied to the detection pattern 61 to which the secondary transfer bias voltage for transferring to the transfer material 51 is not applied. The removed toner can be removed by the intermediate transfer member cleaning device 17 without reattaching to the intermediate transfer member 11. Further, in the present embodiment, a primary bias voltage application device capable of applying a voltage of the same polarity in addition to the voltage of the opposite polarity to the toner of the first embodiment, and a primary transfer member contacting / separating member of the second embodiment. Since no device is required, the image forming apparatus can be configured at low cost.

[0015]

As described above, according to the first aspect of the present invention, since the toner image is not transferred to the intermediate transfer member, the toner removed from the density detection pattern does not adhere to the intermediate transfer member cleaning device, and the transfer is performed. The detection pattern to which the secondary transfer bias voltage for transferring to the transfer material is not applied can be removed without reattaching to the intermediate transfer body, and the risk of the transfer material becoming dirty can be reduced. Claim 2
According to the present invention, since the toner image is not transferred to the intermediate transfer member, the same effect as in claim 1 is obtained. Further, since the intermediate transfer member can be brought into contact with or separated from the image carrier, the image carrier and the intermediate Wear due to contact of the transfer member can be reduced. According to the third aspect of the present invention, since the toner density detection pattern is removed by the secondary transfer member, the density detection pattern does not reach the intermediate transfer body cleaning device, and is removed from the density detection pattern by the intermediate transfer body cleaning device. The adhered toner does not adhere. Therefore, the detection pattern to which the secondary transfer bias voltage for transferring to the transfer material is not applied can be removed without reattaching to the intermediate transfer body. According to a third aspect of the present invention, there is provided a primary bias voltage applying device capable of applying a voltage of the same polarity in addition to a voltage of the opposite polarity to the toner of the first aspect of the present invention. Since the primary transfer member contacting / separating device is not required, the image forming apparatus can be configured at low cost. According to the present invention of claims 4 and 5,
Since a cleaning bias voltage similar to the secondary transfer bias voltage is applied to the detection pattern to which the secondary transfer bias voltage for transferring to the transfer material is not applied, the density detection pattern adhered to the intermediate transfer body cleaning device. The charging potential of the toner removed from the toner becomes the charging potential when the cleaning bias voltage is applied, and the toner removed from the density detection pattern can be removed by the intermediate transfer body cleaning device without reattaching to the intermediate transfer body. . Further, when the cleaning bias voltage is generated by the secondary transfer bias voltage applying device, it is possible to add only a means for changing the minimum voltage application destination to the conventional image forming device, so that the image forming device can be manufactured at low cost. Can be configured.

[Brief description of the drawings]

FIG. 1 is a side view illustrating a schematic configuration of an image forming apparatus according to a first embodiment of the present invention.

FIG. 2 is a side view illustrating a schematic configuration of an image forming apparatus according to a second embodiment of the present invention.

FIG. 3 is a side view illustrating a schematic configuration of an image forming apparatus according to a third embodiment of the present invention.

FIG. 4 is a side view illustrating a schematic configuration of an image forming apparatus according to a fourth embodiment of the present invention.

FIG. 5 is a side view showing a schematic configuration of a conventional image forming apparatus using an intermediate transfer member.

FIG. 6 is a view of the position of the detection pattern formed on the image carrier as viewed from below.

FIG. 7 is a view of the positions of the toner image and the detection pattern transferred onto the intermediate transfer member as viewed from below.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Image carrier, 2 ... Charging part, 3 ... Optical writing part, 4 ... Developing device, 5 ... Toner density detection part (toner density detection means), 6 ... Image Carrier cleaning unit, 11: intermediate transfer member, 12: primary transfer member, 13, 13a: primary transfer bias voltage applying device (primary transfer bias voltage applying unit), 14, 15, 16
... Driving roller, 17 ... Intermediate transfer member cleaning device, 20 ... Intermediate transfer member cleaning device contact / separation device, 31 ... Secondary transfer member, 32 ... Secondary transfer bias voltage applying device ( Secondary transfer bias voltage applying means),
34: secondary transfer member contact / separation device (secondary transfer member contact / separation means), 35: separation unit, 36: fixing unit, 51 ...
・ Transfer material, 61 ・ ・ ・ Density detection pattern, 71 ・ ・ ・
Toner image, 81 ... Control unit (control means), 91 ...
Primary transfer position, 92 ... secondary transfer position

Claims (5)

[Claims] A toner image forming means for forming a toner image on the image carrier; a toner density detecting means for detecting a density of the toner image formed on the image carrier; and an image carrier at a primary transfer position. And transferring the toner image to a secondary transfer position after receiving the transfer of the toner image by contacting the toner image, and transferring the toner image formed on the image carrier onto the intermediate transfer member at the primary transfer position A primary transfer member, primary transfer bias voltage applying means for supplying a bias voltage having a polarity opposite to that of the toner image to the primary transfer member, and transferring the toner image transferred on the intermediate transfer member to a transfer material at a secondary transfer position A secondary transfer member, a secondary transfer bias voltage applying unit that supplies a bias voltage having a polarity opposite to that of the toner image to the secondary transfer member,
Control means for controlling the operation of each means, wherein the control means controls the formation of the toner density detection pattern at a position outside the transfer image area on the image carrier using the toner image forming means. In the image forming apparatus, the primary transfer bias voltage applying unit can generate a voltage having the same polarity as the toner image in addition to a voltage having a polarity opposite to the polarity of the toner image on the image carrier. The means generates a voltage having a polarity opposite to the polarity of the toner image from the primary transfer bias voltage applying means when the toner image formed on the image carrier is at the primary transfer position,
When the toner density detecting pattern is at the primary transfer position, a voltage having the same polarity as the toner is applied from the primary transfer bias voltage applying means. 2. A toner image forming means for forming a toner image on an image carrier, a toner density detecting means for detecting the density of the toner image formed on the image carrier, and an image carrier at a primary transfer position. And transferring the toner image to a secondary transfer position after receiving the transfer of the toner image by contacting the toner image, and transferring the toner image formed on the image carrier onto the intermediate transfer member at the primary transfer position A primary transfer member, primary transfer bias voltage applying means for supplying a bias voltage having a polarity opposite to that of the toner image to the primary transfer member, and transferring the toner image transferred on the intermediate transfer member to a transfer material at a secondary transfer position A secondary transfer member, a secondary transfer bias voltage applying unit that supplies a bias voltage having a polarity opposite to that of the toner image to the secondary transfer member,
Control means for controlling the operation of each means, wherein the control means controls the formation of the toner density detection pattern at a position outside the transfer image area on the image carrier using the toner image forming means. An image forming apparatus, comprising: a primary transfer member contacting / separating unit configured to allow the primary transfer member to freely contact / separate from an image carrier; wherein the control unit controls a toner image formed on the image carrier to a primary transfer position. When the primary transfer member is in contact with the image carrier by the primary transfer member contacting / separating means, and when the toner density detecting pattern is at the primary transfer position, the primary transfer member is contacted by the primary transfer member contacting / separating means. An image forming apparatus, which is brought into contact with and separated from an image carrier. 3. A toner image forming means for forming a toner image on an image carrier, a toner density detecting means for detecting the density of the toner image formed on the image carrier, and an image carrier at a primary transfer position. And transferring the toner image to a secondary transfer position after receiving the transfer of the toner image by contacting the toner image, and transferring the toner image formed on the image carrier onto the intermediate transfer member at the primary transfer position A primary transfer member, primary transfer bias voltage applying means for supplying a bias voltage having a polarity opposite to that of the toner image to the primary transfer member, and transferring the toner image transferred on the intermediate transfer member to a transfer material at a secondary transfer position A secondary transfer member, a secondary transfer bias voltage applying unit that supplies a bias voltage having a polarity opposite to that of the toner image to the secondary transfer member,
Control means for controlling the operation of each means, wherein the control means controls the formation of the toner density detection pattern at a position outside the transfer image area on the image carrier using the toner image forming means. A secondary transfer member cleaning unit that removes the toner density detection pattern transferred onto the secondary transfer member; and a secondary transfer member that allows the secondary transfer member to freely move toward and away from the intermediate transfer member. When the secondary transfer member comes into contact with the toner density detection pattern on the intermediate transfer member, the control unit controls the intermediate transfer member by the secondary transfer member contact / separation unit. The toner density detecting pattern is transferred onto the secondary transfer member by keeping the secondary transfer member from contacting and separating from the secondary transfer member, and the toner density detecting pattern on the secondary transfer member is removed by the secondary transfer member cleaning means. An image forming apparatus comprising Rukoto. 4. A toner image forming means for forming a toner image on an image carrier, a toner density detecting means for detecting the density of the toner image formed on the image carrier, and an image carrier at a primary transfer position. And transferring the toner image to a secondary transfer position after receiving the transfer of the toner image by contacting the toner image, and transferring the toner image formed on the image carrier onto the intermediate transfer member at the primary transfer position A primary transfer member, primary transfer bias voltage applying means for supplying a bias voltage having a polarity opposite to that of the toner image to the primary transfer member, and transferring the toner image transferred on the intermediate transfer member to a transfer material at a secondary transfer position A secondary transfer member, a secondary transfer bias voltage applying unit that supplies a bias voltage having a polarity opposite to that of the toner image to the secondary transfer member,
Control means for controlling the operation of each means, wherein the control means controls the formation of the toner density detection pattern at a position outside the transfer image area on the image carrier using the toner image forming means. A secondary transfer member contacting / separating means for freely contacting / separating from the secondary transfer member intermediate transfer body; and a bias having a polarity opposite to that of the toner to the toner density detection pattern transferred to the intermediate transfer body. A cleaning bias voltage applying unit that supplies a voltage; and an intermediate transfer body cleaning device that removes a toner density detection pattern transferred to the intermediate transfer body. The control unit includes a secondary transfer member and an intermediate transfer member. When the toner image comes in contact with the toner image, the intermediate transfer member and the secondary transfer member are brought into contact with each other by the secondary transfer member contacting / separating means, and the secondary transfer member and the toner concentration detecting member on the intermediate transfer member are detected. Before the contact with the turn, the secondary transfer member is brought into and away from the intermediate transfer member by the secondary transfer member contact / separation unit, and a bias is applied to the toner density detection pattern on the intermediate transfer member from the cleaning bias voltage applying unit. An image forming apparatus, wherein a pattern for toner concentration detection on an intermediate transfer member is removed by an intermediate transfer member cleaning unit by supplying a voltage. 5. The image forming apparatus according to claim 4, wherein the cleaning bias voltage applying unit that supplies a bias voltage to the toner density detection pattern is located at a position facing the intermediate transfer body cleaning device with the intermediate transfer body therebetween. An image forming apparatus, wherein a bias voltage is supplied to a driving roller installed in a printer.