JP2002169383A - Image forming device and method for controlling stop position of intermediate transfer body of image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device capable of forming a high-quality full color image over a long term, and a method for controlling the stop position of an intermediate transfer body of the image forming device. SOLUTION: An intermediate transfer belt 10 has an elastic layer and the stop position of the belt 10 is controlled so that the non-image area of the belt 10 comes into contact with a photoreceptor 1 based on the position information of the belt 10 obtained by a position detection means at the time of stopping image forming operation. The stop timing is calculated from time required until the turning of the belt 10 is perfectly stopped after a motor is stopped and positional relation between a belt position detecting mark 23 provided on the belt 10 and a mark sensor 24.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intermediate transfer type full-color image forming apparatus using an electrophotographic method such as a copying machine, a printer, and a facsimile, and a method of controlling a stop position of the intermediate transfer member.

[0002]

2. Description of the Related Art In a conventional image forming apparatus, a toner image formed on a first image carrier (hereinafter referred to as a photoconductor) is transferred to a second image carrier (hereinafter referred to as a paper) such as paper. (A transfer material), and thereafter, the toner image on the transfer material is heated and pressed by a fixing device to be fixed. In a conventional image forming apparatus for forming a full-color image, a transfer material held on a transfer material carrier such as a transfer drum is used to transfer developed yellow, magenta, cyan, and black colors to a photoconductor. 2. Description of the Related Art There is known a method in which a transfer material is sequentially transferred to a transfer material on a material carrier, and then the transfer material separated from the transfer material carrier is heated and pressed by a fixing device and fixed to obtain a full-color image.

On the other hand, instead of transferring a toner image to a transfer material on a transfer material carrier, for example, Japanese Patent Application Laid-Open No.
As disclosed in Japanese Unexamined Patent Publication, the respective colors of yellow, magenta, cyan, and black developed on the photoreceptor are sequentially superimposed on the intermediate transfer member (hereinafter, referred to as primary transfer), and formed on the intermediate transfer member. An image forming apparatus in which four color toner images are collectively transferred onto a transfer material (hereinafter, referred to as secondary transfer) and then fixed by a fixing device has also started to operate in the market.

A feature of the above-described color image forming apparatus is that it is not necessary to hold the transfer material on the transfer material carrier unlike the conventional image forming apparatus, and therefore, the thin paper (40 g / m ² ) and the thick paper (2
00g / m ² ), it can be transferred to various types of transfer materials such as postcards and envelopes, and has the advantage of high versatility of the transfer material.

Although the image forming apparatus using the intermediate transfer member has the above-mentioned advantages, it still has the following problems to be solved. 2. Description of the Related Art In recent years, as color electrophotographic apparatuses such as color copiers and color laser printers have increased their operation rates in the market, there has been an increasing demand from users for higher image quality. Further diversifying user needs,
High image quality has also been required for transfer materials such as OHP (overhead projector) sheets, thick paper such as postcards, and envelopes.

However, when a plurality of color toner images formed on the intermediate transfer member pass through the primary transfer nip, the toner images are pressed (hereinafter, referred to as toner aggregation) by a predetermined nip pressure. For this reason, when the toner image on the intermediate transfer member is transferred to the transfer material in the secondary transfer step, FIG.
It has been found that the image omission of a character image or a line image (hereinafter referred to as omission during transfer) occurs as shown in FIG.

In order to solve this problem, for example, an intermediate transfer member having an elastic layer as disclosed in Japanese Patent Application Laid-Open No. 8-262880 has been proposed. When the intermediate transfer member having the elastic layer is used, the nip portion between the photosensitive member and the intermediate transfer member, that is, the primary transfer portion, or the nip portion between the intermediate transfer member and the transfer material, that is, the nip portion in the secondary transfer portion By relieving the pressure, the problem of the conventional intermediate transfer member, that is, the problem of missing characters in the character, is improved.

However, in an image forming apparatus using an intermediate transfer member, as shown in FIG. 4, an intermediate transfer member (intermediate transfer belt 10) and a photosensitive member (belt-shaped photosensitive member 1) are connected to a primary transfer portion (primary transfer bias). Since the roller 11) is always in pressure contact with a predetermined contact pressure, if the contact state continues for a long time, the surface of the intermediate transfer member is dented as shown in FIG. It has been found that transfer omission corresponding to the above occurs. Specifically, as shown in FIG.
In a full solid image or full halftone image,
Transfer omission (streak-shaped portion indicated by X in the figure) occurs in a portion corresponding to the recess of the intermediate transfer member. Intermediate transfer belt 1
Japanese Patent Application Laid-Open No. Hei 9-138592 discloses a method of preventing image defects due to deformation caused by a support roller that stretches a belt. There is disclosed a technique of moving a computer.

However, this method has no effect in a state where the power of the machine is not turned on, that is, in a storage state. A method of keeping the primary transfer nip apart at times other than the printing operation is also conceivable. However, it is necessary to provide a contact / separation mechanism, which is a cost increase factor and is not a good measure.

An object of the present invention is to solve the above-mentioned problems and to provide an image forming apparatus capable of forming a high-quality full-color image for a long period of time and a method of controlling the stop position of the intermediate transfer member.

[0011]

According to a first aspect of the present invention, there is provided an image forming apparatus, comprising: a first image carrier and a first image carrier charged to a predetermined potential; Charging means for causing the electrostatic latent image to be formed on the charged first image carrier; developing means for visualizing the electrostatic latent image with toner of a plurality of colors; and the first image A primary transfer means for sequentially transferring the toner images on the carrier onto the intermediate transfer body; and a primary image transfer means for contacting the back surface of the second image carrier and transferring the toner image on the intermediate transfer body to the second image carrier. A secondary transfer unit, a position detection unit for the intermediate transfer body, a detection unit for detecting the position detection unit, and an image forming apparatus having a stop position control unit for the intermediate transfer body, wherein the intermediate transfer body is at least An elastic layer, and the position detecting means when the image forming operation is stopped From the position information of the resulting intermediate transfer member, characterized in that the non-image area of the intermediate transfer member to control the stop position of the intermediate transfer member in contact with the first image bearing member.

According to a second aspect of the present invention, in order to achieve the above object, in the image forming apparatus of the first aspect, the surface of the intermediate transfer member has a micro rubber hardness of 80 degrees or less.

According to a third aspect of the present invention, in order to achieve the above object, in the image forming apparatus of the first aspect, the surface of the intermediate transfer member has a micro rubber hardness of 75 degrees or less.

According to a fourth aspect of the present invention, in order to achieve the above object, in the image forming apparatus of the first aspect, the surface of the intermediate transfer member has a micro rubber hardness of 70 degrees or less.

According to a fifth aspect of the present invention, in order to achieve the above object, in the image forming apparatus according to any one of the first to fourth aspects, the intermediate transfer member is stretched by a plurality of rollers including at least a driving roller. This is an endless intermediate transfer belt that is bridged, and is characterized by comprising at least an elongation preventing layer and an elastic coating layer.

According to a sixth aspect of the present invention, in the image forming apparatus according to any one of the first to fourth aspects, the intermediate transfer body has at least elasticity on a conductive cylindrical substrate. An intermediate transfer drum provided with a coating layer having the same.

According to a seventh aspect of the present invention, there is provided a method for controlling a stop position of an intermediate transfer member of an image forming apparatus, wherein the first image bearing member and the first image bearing member are charged to a predetermined potential to achieve the above object. Charging means for causing the electrostatic latent image to be formed on the charged first image carrier; developing means for visualizing the electrostatic latent image with toner of a plurality of colors; and the first image A primary transfer means for sequentially transferring the toner images on the carrier onto the intermediate transfer body; and a primary image transfer means for contacting the back surface of the second image carrier and transferring the toner image on the intermediate transfer body to the second image carrier. A secondary transfer unit, a position detection unit for the intermediate transfer body, a detection unit for detecting the position detection unit, and an image forming apparatus having a stop position control unit for the intermediate transfer body, wherein the intermediate transfer body is at least When the image forming operation is stopped, the position From the position information of the resulting intermediate transfer member by a means, characterized in that the non-image area of the intermediate transfer member to control the stop position of the intermediate transfer member in contact with the first image bearing member.

[0018]

Embodiments and examples of the present invention will be described below with reference to the drawings. FIG. 3 shows a color image forming apparatus showing an embodiment of the present invention in which an intermediate transfer member is an intermediate transfer belt. In the figure, reference numeral 1 denotes a photosensitive member which rotates in a direction indicated by an arrow in the figure. In this embodiment, a photosensitive member belt provided with a photosensitive layer on an endless PET film is used. The photoconductor 1 is stretched by a plurality of support rollers including a drive roller. Around the photoconductor 1, a photoconductor cleaning unit 2, a charger 4, an exposure unit 5, an intermediate transfer belt 10, and the like are arranged.

The developing means comprises four developing units, a yellow developing unit 6, a magenta developing unit 7, a cyan developing unit 8, and a black developing unit 9. When forming a full-color image,
A visible image is formed in the order of a yellow developing device 6, a magenta developing device 7, a cyan developing device 8, and a black developing device 9, and the visible images of the respective colors are sequentially superimposed and transferred onto the intermediate transfer belt 10, whereby a full-color image is formed. It is formed.

Incidentally, the toner particle size is 4 by volume average particle size.
It is desirable to be in the range of 10 to 10 μm. If the particle diameter is smaller than this, it becomes a cause of background contamination during development, the fluidity is deteriorated, and further aggregation is apt to occur, so that hollow holes are easily generated. Conversely, if the particle size is larger than this, a high-definition image cannot be obtained due to scattering of toner or deterioration of resolution. In this embodiment, the toner having a volume average particle diameter of 7.5 μm is used.

In FIG. 1, reference numeral 3 denotes a blade of the photosensitive member cleaning unit 2. The intermediate transfer belt 10 includes the driving roller 1
3. It is stretched by a primary transfer bias roller 11 and a secondary transfer opposing roller 12, and is driven by a drive motor (not shown). Note that the primary transfer bias roller 11 is pressed in the direction of the photoconductor 1 by a pressure contact spring 27. Each roller is supported from both sides of the intermediate transfer belt by an intermediate transfer belt unit side plate (not shown).

As shown in FIG. 3, the intermediate transfer belt 10 is an elastic intermediate transfer belt having an elastic layer 41 on a core layer 40 and an elastic layer provided with a surface coating layer 42. The materials of the core layer 40, the elastic layer 41, and the surface coating layer 42 are not particularly limited. In this embodiment, the elastic layer 41 is made of NBR rubber and EPDM rubber, respectively.
A rubber compound kneaded by weight with 25 parts by weight was used. Further, 20 parts by weight of carbon black was added as a conductive agent. After covering this rubber compound tube on the outer periphery of a cylindrical mold, a diameter of 100 mm coated with an adhesive was applied.
An endless core layer 40 made of a plain weave of μm polyester yarn was covered, and the above rubber compound was further laminated and vulcanized. After completion of vulcanization, 100 parts by weight of polyurethane in MEK (methyl ethyl ketone)
A coating obtained by kneading 60 parts by weight of the FE fine powder was spray-coated, and a drying step for removing a solution was performed to form a surface coating layer 42. The thickness of the intermediate transfer belt 10 is 500 μm.
It was adjusted to be.

When the micro rubber hardness of the intermediate transfer belt 10 thus obtained was measured, the peak value was 62 degrees. Note that the measurement of the micro rubber hardness is MI
CRODUROMETER MD-1 type (manufactured by Kobunshi Keiki Co., Ltd.). The micro rubber hardness is an important numerical value for preventing missing characters, and the value is preferably 80 degrees or less, more preferably 75 degrees or less, and further preferably 70 degrees or less.

The method of manufacturing the intermediate transfer belt 10 is a casting method,
There is a centrifugal molding method or the like, and the surface may be polished if necessary. The volume resistivity of the intermediate transfer belt 10 is 10 × 10
Adjust so as to be in the range of ⁸ Ω · cm to 10 × 10 ¹³ Ω · cm. If the volume resistivity and the surface resistivity of the intermediate transfer belt 10 exceed the above ranges, the bias required for the transfer increases, which undesirably increases the power supply cost.
Further, the intermediate transfer belt 1 is used in a transfer process, a transfer material peeling process, and the like.
Since the charging potential of 0 becomes high and self-discharge becomes difficult, it is necessary to provide a charge removing means. When the volume resistivity and the surface resistivity are below the above ranges, the decay of the charging potential is quick, which is advantageous for static elimination by self-discharge.However, since the current at the time of transfer flows in the surface direction, toner scattering occurs. Would. Therefore, it is preferable that the volume resistivity and the surface resistivity of the intermediate transfer belt 10 be within the above ranges.

The volume resistivity and the surface resistivity were measured with a high resistivity meter (manufactured by Mitsubishi Chemical Corporation: Hiresta IP).
An RS probe (inner electrode diameter: 5.9 mm, ring electrode inner diameter: 11 mm) is connected,
00V (surface resistivity is 500V)
The value after seconds was used.

In the figure, reference numeral 19 denotes a belt cleaning unit which can be brought into contact with and separated from the intermediate transfer belt 10.
And a contact / separation mechanism 26 for contacting / separating the yellow image of the first color.
During the belt transfer of the second, third and fourth colors, the contact / separation mechanism 26 is used.
When the secondary transfer is performed, the intermediate transfer belt 10 is pressed away at a predetermined timing to clean the remaining toner. A belt position detection mark 23 is provided at an end of the intermediate transfer belt 10, and by starting an image forming process of each color at a timing when the mark is detected by the mark sensor 24, an accurate color overlap of each color image is performed. It becomes possible.

In the figure, reference numeral 15 denotes a secondary transfer unit, which comprises a secondary transfer bias roller 14 and a contact / separation mechanism 16 for bringing the secondary transfer bias roller 14 into and out of contact with the belt 10. The secondary transfer bias roller 14 is configured by coating a metal core such as SUS with an elastic body such as urethane adjusted to a resistance value of 10 ⁶ to 10 ¹⁰ Ω by a conductive material. If the resistance value of the secondary transfer bias roller 14 exceeds the above range, it becomes difficult for the current to flow, so that a higher voltage must be applied to obtain the necessary transferability, which leads to an increase in power supply cost. In addition, since a high voltage is applied, a discharge occurs in a gap before and after the transfer portion nip, and white spots are generated on the halftone image due to the discharge. Conversely, if the resistance value of the secondary transfer bias roller 14 falls below the above range, transferability between a multi-color image portion (for example, a three-color superimposed image) and a single-color image portion existing on the same image becomes incompatible. This is because the resistance value of the secondary transfer bias roller 14 is low, so that a sufficient current flows to transfer a single-color image portion at a relatively low voltage, but it is most suitable for a single-color image portion to transfer a multi-color image portion. Since a voltage value higher than the required voltage is required, if the voltage is set to a value at which the multi-color image portion can be transferred, the transfer current becomes excessive for a single-color image, resulting in a reduction in transfer efficiency.

The resistance value of the secondary transfer bias roller 14 was measured by placing the secondary transfer bias roller 14 on a conductive metal plate and placing 4.9 N on one side at both ends of the metal core (a total of 9.8 N on both sides). ) Is calculated from the value of the current flowing when a voltage of 1000 V is applied between the cored bar and the metal plate in a state where the load is applied. A driving force is applied to the secondary transfer bias roller 14 by a driving gear (not shown), and its peripheral speed is adjusted to be substantially the same as the peripheral speed of the intermediate transfer belt 10.

Although the secondary transfer bias roller 14 is normally separated from the surface of the intermediate transfer belt 10, the intermediate transfer belt 1
When the four-color superimposed images formed on the surface 0 are collectively transferred to the transfer material 22, they are pressed by the contact / separation mechanism 16 in a timely manner, and a predetermined bias voltage is applied by the high-voltage power supply 100 to the transfer material 22. Is performed.

The transfer material 22 is fed by the feed roller 25 and the registration roller 21 at the timing when the leading end of the four-color superimposed image on the surface of the intermediate transfer belt 10 reaches the secondary transfer position. The four-color superimposed image transferred to the transfer material 22 is discharged after being fixed by the fixing unit 17.

When forming a full-color image, first, the photosensitive member 1
Is uniformly charged to a surface potential of -500 V by the charger 4 and then exposed by the exposure means 5 to form an electrostatic latent image, thereby writing an image. Is visualized by a one-component developer composed of yellow toner by a yellow developing device 6 to become a yellow image (yellow toner image). At this time, the developing bias applied to the yellow developing device 6 is -300V. The transfer bias is applied to the primary transfer bias roller 11 from a high-voltage power supply (not shown), and the primary transfer bias roller 11 contacts the back surface of the intermediate transfer belt 10 to apply a charge to transfer the yellow image on the photoconductor 1 to the intermediate transfer belt 10. The primary transfer bias at this time is 1
000V. The photoconductor 1 is cleaned by the photoconductor cleaning unit 2 after the transfer of the yellow image.

Next, the photoreceptor 1 is uniformly charged to a surface potential of -500 V by the charger 4 and thereafter exposed by the exposure means 5 to form an electrostatic latent image, thereby writing an image. The electrostatic latent image on the photoreceptor 1 is
Is visualized with a one-component developer composed of magenta toner to form a magenta image (magenta toner image). The developing bias applied to the magenta developing device 7 is -300 V
It is. The primary transfer bias roller 11 transfers a magenta image on the photoreceptor 1 to the intermediate transfer belt 10 by applying a transfer bias from a high-voltage power supply and contacting the back surface of the intermediate transfer belt 10 to apply a charge. At this time, the primary transfer bias was set to 1200V. The photoconductor 1 is cleaned by the photoconductor cleaning unit 2 after the transfer of the magenta image.

Next, the photoreceptor 1 is uniformly charged to a surface potential of -500 V by the charger 4 and then exposed by the exposure means 5 to form an electrostatic latent image, thereby writing an image. The electrostatic latent image on the photoreceptor 1 is visualized by a cyan developing device 8 with a one-component developer composed of cyan toner to become a cyan image (cyan toner image). At this time, the developing bias applied to the cyan developing device 8 is -300V.
A transfer bias is applied to the primary transfer bias roller 11 from a high-voltage power supply, and the primary transfer bias roller 11 contacts the back surface of the intermediate transfer belt 10 to apply a charge, thereby converting the cyan image on the photoreceptor 1 to the intermediate transfer belt 10 with a yellow image and a magenta image. Transfer by overlapping. The primary transfer bias at this time is 1400
V was set. The photoconductor 1 is cleaned by the photoconductor cleaning unit 2 after the transfer of the cyan image.

Further, the photoreceptor 1 is uniformly charged to a surface potential of -500 V by the charger 4 and then exposed by the exposure means 5 to form an electrostatic latent image, thereby writing an image. The electrostatic latent image on the photoreceptor 1 is visualized by a black developing device 9 with a one-component developer composed of black toner to become a black image (black toner image). At this time, the developing bias applied to the black developing device 9 is -30.
0V. The primary transfer bias roller 11 is applied with a transfer bias from a high voltage power supply and contacts the back surface of the intermediate transfer belt 10 to apply an electric charge, thereby converting the black image on the photoconductor 1 to the intermediate transfer belt 10 to a yellow image, a magenta image, The image is transferred by being superimposed on the cyan image. At this time, the primary transfer bias was set to 1600V. The photoconductor 1 is cleaned by the photoconductor cleaning unit 2 after the transfer of the black image.

The full-color image (four-color superimposed image) on the intermediate transfer belt 10 is transferred by the secondary transfer bias roller 14 to the transfer material 22 fed from the paper feed device by the paper feed roller 25 and the registration roller 21. , Transfer material 2
2 is discharged after the image transferred from the intermediate transfer belt 10 is fixed by the transfer unit 17.

In this embodiment, a single-color mode for forming an image of any one of yellow, magenta, cyan and black, and a two-color mode for forming an image of any two colors of yellow, magenta, cyan and black are superposed. Mode, yellow,
There are a three-color mode in which three-color images of magenta, cyan, and black are formed in a superimposed manner, and a full-color mode in which a four-color superimposed image is formed as described above, and these modes can be designated by the operation unit. .

When one of the single-color mode, the two-color mode, and the three-color mode is designated, images of respective colors of yellow, magenta, cyan, and black are formed on the photosensitive member 1 in the full-color mode as described above. Intermediate transfer belt 1
0, an operation of forming an image on the photoconductor 1 in a single color corresponding to the single-color mode and transferring the image to the intermediate transfer belt 10, or an operation of transferring the two-color image corresponding to the two-color mode to the photoconductor 1 The operation of forming an image of three colors corresponding to the three-color mode on the photosensitive member 1 and transferring the image to the intermediate transfer belt 10 is performed until the operation of forming the image on the intermediate transfer belt 10 is performed. The single-color image, the two-color superimposed image, or the three-color superimposed image is transferred to the transfer material 22 by the secondary transfer bias roller 14 and fixed by the fixing unit 17 and then discharged.

When the image forming operation for forming the superimposed images of a plurality of colors on the transfer material 22 is continuously performed by the number of sheets set by the operation unit, the rear end of the transfer material 22 sufficiently passes through the secondary transfer bias roller 14. At a timing, the transfer bias voltage from the high-voltage power supply to the secondary transfer bias roller 14 is turned off, and then the toner image of the next page on the intermediate transfer belt 10 is not adhered to the secondary transfer bias roller 14.
The secondary transfer bias roller 14 is separated from the intermediate transfer belt 10 by the contact / separation mechanism 16.

At the end of the last page in single-sheet printing or continuous printing, the secondary transfer bias roller 14 is not separated from the surface of the intermediate transfer belt 10 and a cleaning bias having a polarity opposite to that of the transfer bias (-1 k in this embodiment).
V) is applied for a certain period of time to transfer the toner adhered to the surface of the secondary transfer bias roller 14 to the intermediate transfer belt 10, thereby cleaning the surface of the secondary transfer bias roller 14, and thereafter separating from the intermediate transfer belt 10. .
The toner transferred to the intermediate transfer belt 10 is collected from the belt surface by a belt cleaning unit 19. Then, after the above-described series of printing operations is completed, the rotation of the motor is stopped and the apparatus enters a standby state.

The circumference of the intermediate transfer belt 10 is
The maximum transfer paper length that can be printed is calculated in consideration of the time required for the contact / separation operation of the belt cleaning unit 19, the margin time for the variation, and the process speed. In this embodiment, the maximum transfer paper length is 18 inches (45 inches).
7.2 mm), time required for the contact / separation operation = 0.3 second, margin for variation = 0.1 second, process speed = 1
80 mm / sec, so the intermediate transfer belt circumference = 45
7.2+ (0.3 + 0.1) × 180 = 529.2 mm
Becomes

At this time, the non-image area is (0.3 + 0.1)
× 180 = 72 mm, so that this non-image area is in contact with the primary transfer nip when the motor is stopped. The stop timing can be easily calculated from the time Tb from the stop of the motor until the rotation of the intermediate transfer belt 10 is completely stopped, and the positional relationship between the belt position detection mark 23 provided on the intermediate transfer belt 10 and the mark sensor 24. It is.

When the image forming operation is completed, the non-image area Y of the intermediate transfer belt 10 is stopped so as to be in contact with the primary transfer nip as shown in FIG. Even if placed in a state,
The primary transfer nip portion of the intermediate transfer belt 10 does not cause image defects such as transfer omission due to deformation.

FIG. 8 is a diagram showing an outline of a second embodiment of the present invention. The difference from the first embodiment is that an elastic layer and a surface coat layer are provided on a metal drum instead of an intermediate transfer belt. This is the point that the intermediate transfer drum 37 is used. Note that the other components are assigned the same reference numerals, and duplicate descriptions are omitted.

In the present embodiment, as in the first embodiment, the object of the present invention is achieved by making the non-image area come into contact with the primary transfer nip when the motor is stopped. The stop timing is the time Td from the stop of the motor to the complete stop of the rotation of the intermediate transfer drum 37, and the time Td from the stop of the intermediate transfer drum 37.
It can be easily calculated from the positional relationship between the belt position detection mark 23 provided above and the mark sensor 24. Also,
By using the intermediate transfer drum as the intermediate transfer body as in the present embodiment, it is possible to obtain a good high-quality full-color image for a long time without color misregistration in the width direction and without omission during transfer. Was.

The embodiments described above are intended to facilitate understanding of the present invention, and the present invention is not limited to these embodiments. For example, in the above-described embodiment, the description has been made using the photosensitive belt or the photosensitive drum as the latent image carrier, but the present invention is not limited to this, and may be applied to all other latent image carriers. Applicable. Furthermore, transfer rollers were used as the primary transfer means and the secondary transfer means, but not only rotary contact transfer methods such as rotary transfer brushes, but also contact transfer methods such as transfer belts, transfer brushes, transfer blades, and transfer plates. The present invention can be applied to an image forming apparatus using the image forming apparatus.

[0046]

As described above, the image forming apparatus according to the first aspect of the present invention includes the first image carrier and the first image carrier.
Charging means for charging the image carrier at a predetermined potential, exposure means for forming an electrostatic latent image on the charged first image carrier, and developing means for visualizing the electrostatic latent image with a plurality of color toners Primary transfer means for sequentially transferring the toner image on the first image carrier onto the intermediate transfer member; and contacting the back surface of the second image carrier with the toner image on the intermediate transfer member to form a second image Secondary transfer means for transferring to the carrier, a position detection unit of the intermediate transfer body,
In an image forming apparatus having a detection unit for detecting a position detection unit and a stop position control unit for the intermediate transfer body, the intermediate transfer body has at least an elastic layer and is obtained by the position detection unit when the image forming operation is stopped. By controlling the stop position of the intermediate transfer member from the position information of the intermediate transfer member so that the non-image area of the intermediate transfer member is in contact with the first image carrier, it is possible to prevent the transfer omission due to toner aggregation. In addition, even when the image forming apparatus is left for a long time, a high-quality full-color image can be obtained.

In the image forming apparatus according to the second aspect, as described above, since the micro rubber hardness of the surface of the intermediate transfer member is 80 degrees or less, it is possible to prevent the omission during transfer due to the aggregation of the toner. There is an effect that a high-quality full-color image can be obtained.

In the image forming apparatus according to the third aspect, since the micro rubber hardness of the surface of the intermediate transfer member is set to 75 degrees or less as described above, it is possible to prevent omission during transfer due to toner aggregation. There is an effect that a high-quality full-color image can be obtained.

According to the image forming apparatus of the present invention, as described above, since the micro rubber hardness of the surface of the intermediate transfer member is set to 70 degrees or less, it is possible to prevent omission during transfer due to toner aggregation. There is an effect that a high-quality full-color image can be obtained.

According to a fifth aspect of the present invention, as described above, the intermediate transfer member is an endless intermediate transfer belt stretched by a plurality of rollers including at least a driving roller, and at least an elongation preventing belt. By using a layer and a coating layer having elasticity, the degree of freedom in the layout of the intermediate transfer member is increased, so that a space-saving design can be achieved, and a dropout during transfer can be prevented, and a high-quality full-color image can be obtained. There is.

According to the image forming apparatus of the present invention, as described above, the intermediate transfer member is an intermediate transfer drum in which at least an elastic coating layer is provided on a conductive cylindrical substrate, so that the width of the image forming apparatus in the width direction can be improved. There is an effect that no color misregistration occurs, omission during transfer can be prevented, and a high-quality full-color image can be obtained.

According to a seventh aspect of the present invention, as described above, the first image carrier and the charging means for charging the first image carrier to a predetermined potential are provided. Exposure means for forming an electrostatic latent image on the charged first image carrier, developing means for visualizing the electrostatic latent image with toner of a plurality of colors, and a toner image on the first image carrier Primary transfer means for sequentially transferring the toner image onto the intermediate transfer member, and contacting the back surface of the second image carrier to transfer the toner image on the intermediate transfer member to the second transfer member.
An image forming apparatus comprising: a secondary transfer unit for transferring the image to the image carrier; an intermediate transfer body position detection unit; a detection unit for detecting the position detection unit; and a stop position control unit for the intermediate transfer body. The body has at least an elastic layer, and based on the position information of the intermediate transfer body obtained by the position detecting means when the image forming operation is stopped, the non-image area of the intermediate transfer body is brought into contact with the first image carrier. By controlling the stop position of, the transfer omission due to toner aggregation can be prevented,
In addition, there is an effect that a high-quality full-color image can be obtained even when the image forming apparatus is left for a long time.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a laser printer using an intermediate transfer belt according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram for explaining a hollow phenomenon.

FIG. 3 is a diagram illustrating a cross-sectional configuration of an intermediate transfer belt.

FIG. 4 is an enlarged explanatory view of a pressure contact portion between an intermediate transfer belt and a photosensitive member.

FIG. 5 is an explanatory diagram of a state in which a permanent distortion occurs in the intermediate transfer belt.

FIG. 6 is an explanatory diagram of a transfer missing image due to permanent distortion of the intermediate transfer belt.

FIG. 7 is a diagram illustrating a contact state between a non-image area of the intermediate transfer belt and a photoconductor when the image forming apparatus is stopped.

FIG. 8 is a schematic diagram illustrating a configuration of a laser printer using an intermediate transfer belt according to a second embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 photoconductor 2 photoconductor cleaning unit 3 blade of photoconductor cleaning unit 4 charger 5 exposure means 6 yellow developing device 7 magenta developing device 8 cyan developing device 9 black developing device 10 intermediate transfer belt 11 primary transfer bias roller 12 secondary transfer Opposing roller 13 Drive roller 14 Secondary transfer bias roller 15 Secondary transfer unit 16 Contact / separation mechanism 17 Fixing means 19 Belt cleaning unit 21 Registration roller 22 Transfer material 23 Belt position detection mark 24 Mark sensor 25 Feed roller 26 Contact / separation mechanism 27 Pressing spring 37 Intermediate transfer drum 40 Core layer 41 Elastic layer 42 Surface coating layer

Claims (7)

[Claims] A first image bearing member, a charging means for charging the first image bearing member to a predetermined potential, and an exposure for forming an electrostatic latent image on the charged first image bearing member. Means, developing means for visualizing the electrostatic latent image with toner of a plurality of colors, primary transfer means for sequentially transferring the toner image on the first image carrier to an intermediate transfer body, and second image carrier Secondary transfer means for contacting the back surface of the body to transfer the toner image on the intermediate transfer body to the second image carrier, a position detection unit for the intermediate transfer body, and detection means for detecting the position detection unit And, in the image forming apparatus having the intermediate transfer body stop position control means, the intermediate transfer body has at least an elastic layer,
When the image forming operation is stopped, the stop position of the intermediate transfer body is controlled based on the position information of the intermediate transfer body obtained by the position detection unit so that the non-image area of the intermediate transfer body is in contact with the first image carrier. An image forming apparatus. 2. The image forming apparatus according to claim 1, wherein the surface of said intermediate transfer member has a micro rubber hardness of 80 degrees or less. 3. The image forming apparatus according to claim 1, wherein the surface of said intermediate transfer member has a micro rubber hardness of 75 degrees or less. 4. The image forming apparatus according to claim 1, wherein the surface of said intermediate transfer member has a micro rubber hardness of 70 degrees or less. 5. The image forming apparatus according to claim 1, wherein the intermediate transfer body is an endless intermediate transfer belt stretched by a plurality of rollers including at least a drive roller, and at least prevents elongation. An image forming apparatus comprising a layer and a coating layer having elasticity. 6. The image forming apparatus according to claim 1, wherein the intermediate transfer body is an intermediate transfer drum having a conductive cylindrical substrate provided with a coating layer having at least elasticity. Image forming apparatus. 7. A first image carrier, charging means for charging the first image carrier to a predetermined potential, and exposure for forming an electrostatic latent image on the charged first image carrier. Means, developing means for visualizing the electrostatic latent image with toner of a plurality of colors, primary transfer means for sequentially transferring the toner image on the first image carrier to an intermediate transfer body, and second image carrier Secondary transfer means for contacting the back surface of the body to transfer the toner image on the intermediate transfer body to the second image carrier, a position detection unit for the intermediate transfer body, and detection means for detecting the position detection unit And, in the image forming apparatus having the intermediate transfer body stop position control means, the intermediate transfer body has at least an elastic layer,
When the image forming operation is stopped, the stop position of the intermediate transfer body is controlled based on the position information of the intermediate transfer body obtained by the position detection unit so that the non-image area of the intermediate transfer body is in contact with the first image carrier. A method of controlling a stop position of an intermediate transfer member of an image forming apparatus.