JPH06295111A - Image forming device - Google Patents

Abstract

PURPOSE:To remove residual toner, a toner filming layer or the like by an optimum condition by comparing the detected value of surface potential with a reference value and removing the toner filming layer formed on a carrier based on the compared result. CONSTITUTION:An insulating contact member is constituted of a roller body (roller) 19 consisting of a rotatable and insulating body. The roller 19 is constituted so as to be freely brought into contact with an intermediate transfer belt 15. It is assumed that the detected potential value by a surface potential detection device 21 just after the belt 15 and the roller 19 are separated is defined as V0 and the previously set reference value is defined as Vs. When the detected value V0 becomes equal to or under the reference value Vs, it is detected by a surface state detection means based on the compared result from a comparison means that the toner filming layer is formed on the belt 15. Based on the output thereof, a toner filming removing member 24 abuts on the belt 15 while rotating, and the toner filming layer is removed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a copying machine, a printer,
The present invention relates to an image forming apparatus using an analog or digital electrophotographic system such as a facsimile, and more specifically, a carrier that carries a supported object such as a toner image or a recording medium and conveys the supported object until the next step. The present invention relates to an image forming apparatus having the same.

[0002]

2. Description of the Related Art Conventionally, when toner that has not contributed to transfer adheres to a carrier such as a photosensitive member or an intermediate transfer member, it is removed by a cleaning device by the next image forming cycle. However, such cleaning methods include various methods such as a blade cleaning method in which an edge of urethane rubber is pressed against a carrier to scrape off toner, and a fur brush cleaning method using a bristle brush.

Particularly, the blade cleaning method is widely used because it is mechanically simple and inexpensive.

However, when a toner melted by heat or pressure or a toner having a fine particle diameter adheres to a carrier such as a photoconductor or an intermediate transfer member in a state in which it is difficult to separate, it cannot be completely removed by the blade alone. A filming layer of toner is gradually formed on the carrier. In this case, the transfer performance when the toner image is transferred to the recording medium deteriorates, and the image quality deteriorates. In particular, in the case of the double transfer method using the intermediate transfer member, the transfer efficiency is greatly reduced even with a slight filming.

Further, when the toner filming layer is formed on the carrier, the coefficient of friction between the blade and the carrier increases, so that when the counter blade system is used, the entanglement of the blade is likely to occur. Further, when the carrier is a belt member stretched by a driving roller and a driven roller, the driving roller will idle due to an increase in frictional force between the blade and the carrier.

Therefore, conventionally, for example, Japanese Unexamined Patent Publication No. 2-214 is used.
As disclosed in Japanese Patent No. 882, the cleaning roller is rubbed against the carrier to remove the toner filming layer. However, when the toner filming layer is removed by the cleaning roller as described above, the carrier may be rubbed too much, which may deteriorate the carrier early.

Therefore, as disclosed in Japanese Patent Laid-Open No. 2-262180, the timing at which the cleaning roller rubs the carrier is set to once every several copies, and the carrier rubs. Techniques for preventing overshoot have also been proposed. However, even if such a configuration is adopted, the generation state of filming changes depending on the usage conditions of the image forming apparatus, so that it may not be applicable to all usage environments.

If it is possible to directly detect the amount of toner filming produced, it is possible to perform an optimum removal operation according to the detection result, but it has been difficult to detect the removal operation.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus capable of detecting a toner filming layer on a carrier and easily eliminating the above-mentioned conventional drawbacks. is there.

[0010]

In order to achieve the above object, the present invention provides a carrier for carrying a toner image or a recording medium as an object to be carried and driven so that the object is carried. A cleaning device for removing toner and other deposits remaining on the carrier, an insulative contact member that can be brought into contact with and separated from the carrier, and an insulating member in a state of being in contact with the carrier. Potential detecting means for detecting the surface potential of the insulating contact member portion brought into contact with the carrier when the conductive contact member is separated from the carrier, and detection by the potential detecting means. An image having a comparing means for comparing the value with a predetermined reference value, and a filming layer removing means for removing the toner filming layer formed on the surface of the carrier based on the comparison result by the comparing means. Forming equipment Suggest.

In order to achieve the same object, a carrier which carries a toner image or a recording medium as a supported object and is driven so that the supported object is conveyed, and a residual toner on the carrier. And a cleaning device for removing other deposits, a medium resistance contact member supported by a conductive support member and configured to come into contact with and separate from the carrier, and a medium resistance in a state of being brought into contact with the carrier. When the contact member is separated from the carrier, immediately after the separation, a potential detecting means for detecting the potential of the supporting member is compared with a detection value by the potential detecting means and a predetermined reference value. There is proposed an image forming apparatus having a means and a filming layer removing means for removing the toner filming layer formed on the surface of the carrier based on the comparison result by the comparing means.

At this time, it is advantageous that the contact member also serves as the filming layer removing means.

Further, in order to achieve the above-mentioned object, a carrier which carries a toner image or a recording medium as a supported object and is driven so that the supported object is conveyed, and a toner image on the carrier. Transfer means for transferring the toner, a cleaning device for removing the toner and other adhering substances remaining on the carrier after the transfer, and an insulating contact member that can be brought into contact with and separated from the carrier. When the insulating contact member in contact with the carrier is separated from the carrier, immediately after the separation, the surface potential of the insulating contact member portion in contact with the carrier is detected. Potential detection means,
An image forming apparatus is proposed which has a comparison means for comparing the detection value of the potential detection means with a predetermined reference value, and a control means for controlling the output of the transfer means based on the comparison result of the comparison means. .

Further, in order to achieve the above-mentioned object, a carrier for supporting a toner image or a recording medium as an object to be carried and driven so that the object to be carried is conveyed, and a toner image on the carrier. A transfer device for transferring the toner, a cleaning device for removing residual toner and other adhered substances on the carrier after the transfer, and a cleaning device configured to be contactable with and separated from the carrier and supported by a conductive support member. A medium resistance contact member and a medium resistance contact member in a state of being in contact with the carrier, and when separated from the carrier, immediately after this separation, a potential detecting means for detecting the potential of the supporting member, An image forming apparatus is proposed which has a comparison means for comparing the detection value of the potential detection means with a predetermined reference value, and a control means for controlling the output of the transfer means based on the comparison result of the comparison means. To do.

In this case, in each of the above constructions, the contact member is composed of a rotatable roller body, and a cleaning member for cleaning the surface of the roller body and a downstream side of the cleaning member in the rotation direction of the roller body. It is effective to have the roller body surface charge eliminating member provided on the.

The medium resistance contact member is a brush made of medium resistance fiber, and it is effective to bring a flicker member electrically floated into contact with the brush.

Further, in each of the above-mentioned constitutions, it is effective to provide a charge removing means for the carrier on the contact portion between the carrier and the contact member or on the upstream side of the contact portion in the moving direction of the carrier. is there.

Further, in each of the above-mentioned configurations, it is effective to provide a humidity detecting sensor for detecting the humidity in the vicinity of the contact member and a correcting means for correcting the reference value according to the detected value of the sensor.

Further, in each of the above-mentioned constitutions, the potential change for detecting the amount of potential change by comparing the detection value of the potential detection means immediately after the carrier and the contact member are separated from each other and the detection value after a fixed time. It is effective to have a detection unit and a correction unit that corrects the reference value according to the potential change amount.

Further, in each of the above-mentioned constitutions, the main component of the material constituting the carrier and the contact member is a polymer material, and the relative permittivity of the main component of the carrier and the main component of the contact member. It is effective that the difference of 0.5 is 0.5 or more.

[0021]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a diagram showing only a main part of a potential detecting component of a contact member provided in an image forming apparatus according to an embodiment of the present invention.

Prior to explaining the detection component,
The outline of the overall configuration of the image forming apparatus will be clarified below with reference to FIG.

In the figure, around a drum-shaped photoconductor 1 which is an example of a latent image carrier, a charging charger 2, a developing device 4, a belt transfer roller 5, a photoconductor cleaning device 6, and a discharging lamp 7 are provided. Are arranged respectively. The intermediate transfer belt 15 is stretched around the belt transfer roller 5, the driven roller 8, the belt driving roller 9, and the backup roller 10.

First, the surface of the photosensitive member 1 which is rotationally driven in the direction of the arrow in the figure is uniformly charged by the charging charger 2.
A predetermined electrostatic latent image is formed on the surface of the charged surface by performing a predetermined image exposure in the exposure unit 3. This electrostatic latent image is visualized as a toner image by the developing device 4 in the next step.

The toner image is transferred to the belt transfer roller 5 of the intermediate transfer belt 15 to which a transfer bias voltage is applied.
It is electrostatically transferred to the belt part that is stretched over. The cleaning device 6 removes the toner and other deposits remaining on the photoconductor 1 after the transfer of the toner image. Then, the toner image transferred onto the intermediate transfer belt 15 is electrostatically transferred onto the recording medium 16 which is sent between the belt portion which is wound around the belt driving roller 9 and the paper transfer roller 13 which faces the belt portion. Is transcribed to. At this time, the paper transfer roller 13 is pressed against the intermediate transfer belt 15 via the recording medium 16.

The recording medium 16 is made of, for example, a transfer paper, and the transfer paper is used after the transfer of the toner image.
While being electrostatically carried on the sheet 7, it is sent toward the fixing device 18, and the device fixes the transfer toner image on the transfer paper.
After the transfer, the toner remaining on the intermediate transfer belt 15 and other adhering substances are removed by the intermediate transfer belt cleaning device 11.

The above-mentioned cleaning devices 6 and 11 respectively have blades 6a and 11a which are pressed against the photoconductor 1 or the intermediate transfer belt 15 to remove the residual toner.

Here, the intermediate transfer belt 15 is an example of a carrier for carrying a toner image as a carried object, and is driven so as to convey such a carried object. That is, the intermediate transfer belt 15 is driven in the direction of the arrow in the figure by the rotation of the belt driving roller 9, and the photoconductor 1
The toner image transferred from is conveyed to the second transfer section of the next process section. Here, the second transfer portion is a transfer portion in the part of the paper transfer roller 13.

As the carrier, a latent image carrier such as the photoconductor 1 carrying the toner image may be used. In this case, the photoconductor includes a single-type photoconductor that does not use the intermediate transfer belt 15 in combination, and a belt-shaped photoconductor other than the drum is also applicable.
Further, although not shown in the figure, when the transfer paper is carried and conveyed to the transfer unit or the fixing device and the toner image is transferred from the photoconductor or the intermediate transfer belt to the transfer paper, the transfer paper is used as the photoconductor or the intermediate transfer belt. The transport belt and the like that come into contact with the carrier also constitute an example of the configuration of the carrier, and since toner remains on the transport belt, the toner and other deposits are removed by a cleaning device (not shown). .
Since the toner adheres to any of these examples of the carrier, a filming layer may be formed by the toner, and the above-described problems such as a decrease in the transfer efficiency of the toner image may occur due to the formation of the filming layer. May occur.

As described above, the present invention carries a toner image or a recording medium as a carried object, and the carrying body driven to convey the carried object is an intermediate transfer body such as an intermediate transfer belt. The present invention is widely applicable when it is composed of a latent image carrier such as a photoconductor or a recording medium transport member such as a transport belt. However, for the sake of convenience, the above-mentioned intermediate transfer belt 15 will be given as an example of the carrier. I will continue to explain.

Returning to FIG. 1, for the sake of convenience, the intermediate transfer belt 15 is in a state of being stretched around the belt portion wound around the driven roller 8 in this figure.

An insulating contact member 19 is disposed on the side of the belt surface facing the driven roller 8 with the intermediate transfer belt 15 interposed therebetween. In this example, the insulating contact member 19 is composed of a rotatable roller body (hereinafter referred to as “roller”) made of an insulating material. And
The roller 19 is configured to be in contact with the intermediate transfer belt 15. For example, a driving means such as a solenoid (not shown) is driven to displace the contact position shown by a solid line and the separated position shown by a broken line.

The roller 19 comes into contact with the intermediate transfer belt 15 whose surface is cleaned by the cleaning device 11 shown in FIG. 3 and which does not carry a toner image, at an appropriate time.

Here, the intermediate transfer belt 15 in the present example.
Is a medium resistance belt having a volume resistivity of about 10 ^{5 to} 10 ⁸ Ω · cm. When the intermediate transfer belt 15 is contacted with a roller 19 made of an insulating material, charge carriers are transferred from one side to the other side. A charge double layer is generated near the interface.
The time required for the charge transfer to reach an equilibrium state is expressed by the following equation. Relaxation time τ = ε ₀ ε ₁ ρ ε ₀ : Dielectric constant in vacuum ε ₁ : Dielectric constant ρ: Solid resistance (Ω · cm)

After τ hours from the start of contact, when the two are separated from each other, most of the transferred charges remain. This is because in the case of an insulating material, the charges are trapped in the traps and exist as space charges, so the distance between the centers of gravity of the positive and negative charges is large, and even if the separation is started, the backflow of charges due to the tunnel effect is desired. Because there is no. Further, it is unlikely that the charged electric charge bypasses the convex portion that is finally separated to neutralize. Therefore, the insulator is relatively easy to take out as static charge without losing the transferred charge. After separation, the amount of electric charge is attenuated due to leakage.

When the intermediate transfer belt 15 and the roller 19 are separated from each other, immediately after this, the roller 19 is rotated by about 90 ° in the clockwise direction in the drawing by a rotation driving means (not shown), and as shown in FIG. The roller portion 19A that was in contact with the intermediate transfer belt 15 is opposed to the sensor portion 22 of the surface potential detecting device 21.

The surface potential detecting device 21 comprises a sensor portion 22 also called a surface potential measuring probe and a sensor main body portion (surface potential meter) 23, and detects the surface potential of the roller portion 19A. Here, the toner image carrying surface of the intermediate transfer belt 15 is the surface on the roller 19 side, but this surface is the surface on which a filming layer of toner is formed.

If the toner filming layer is not present on such a surface or if it is relatively light, the surface potential of the roller portion 19A becomes large, but the filming layer is remarkably formed. Then, the surface potential tends to decrease. This point will be described in detail later.

The surface potential detecting device 2 measures the magnitude of such potential.
By detecting with 1, it is possible to detect whether or not the toner filming layer is formed. To detect the toner filming layer on the intermediate transfer belt 15 by measuring the residual charging potential of the insulating contact member after the separation, which is generated due to the contact potential difference between the intermediate transfer belt 15 and the insulating contact member. Can be done.

Even when the intermediate transfer belt 15 or the other carrier described above is not a medium resistance body but a high resistance body or a low resistance body, the filming layer can be detected in the same manner as described above. It is possible to detect the volume resistivity of the carrier at any time.

In the surface potential detecting device 21, the insulative contact member which is in contact with the carrier is used as the carrier 15.
This is an example of a potential detecting means for detecting the surface potential of the insulating contact member portion brought into contact with the carrier immediately after being separated from the carrier.

A value detected by such a potential detecting means,
By comparing a predetermined reference value with a comparison unit (not shown), the formation state of the toner filming layer can be detected, and the filming layer can be efficiently removed. Alternatively, the transfer conditions can be changed as described later. For example, assuming that the reference value is a reference value corresponding to a state immediately before the worst state of forming the toner filming layer, the potential detecting means determines that the potential (the degree of forming the toner filming layer is further increased) deviates from the reference value. When a potential in the worsening direction) is detected, for example, in FIG.
The toner filming layer can be removed by an appropriate filming layer removing means composed of the filming layer removing member 24 shown in FIG. 1 to prevent the worst filming layer formation state.

The filming layer removing member 24 is, for example, in the shape of a roller or a brush, and the intermediate transfer belt 15 is used.
The intermediate transfer belt 1 is supported so that it can come into contact with and separate from the surface of the intermediate transfer belt 1.
When the toner filming layer on 5 is removed, it comes into contact with the intermediate transfer belt 15 while rotating and gives a polishing action to the belt 15 to remove the filming layer.

More specifically, the intermediate transfer belt 15
The potential detection value by the surface potential detection device 21 immediately after the roller 19 is separated from the roller 19 is V ₀ , and a preset reference value is Vs.
Then, when V ₀ becomes equal to or lower than the reference value Vs, the surface state detection unit (not shown) detects that the toner filming layer is formed on the intermediate transfer belt 15 based on the result of the comparison unit. By the output, the filming layer removing member 24 contacts the intermediate transfer belt 15 while rotating as described above, and removes the toner filming layer.
Then, the filming layer removing member 24 is operated for a predetermined time, or when it is detected that the toner filming layer on the intermediate transfer belt has disappeared or has decreased, the filming layer removing member 24 is moved to the intermediate position. The transfer belt 15 is separated, and the filming layer removing operation is stopped.

As described above, it is possible to prevent the toner filming layer from being formed on the intermediate transfer belt 15 so as to reduce the transfer efficiency of the toner image, and only when the toner filming layer is formed. Since the filming layer removing operation is performed by the removing member 24, it is possible to prevent a problem that the intermediate transfer belt 15 is rubbed too much and deteriorates early. In this way, it is possible to prevent the transfer efficiency from being lowered due to the formation of the toner filming layer, and to prevent the blade 11a of the cleaning device 11 from being caught up, thereby ensuring stable image formation for a long period of time.

The filming layer removing operation is naturally performed on the intermediate transfer belt 15 on which the toner image obtained by the normal image forming operation is not formed.

The comparison means is composed of a known comparison circuit or the like, and the comparison means compares the value detected by the potential detection means with a predetermined reference value. Based on the comparison result, an intermediate value is obtained. The toner filming layer formed on the surface of the carrier such as the transfer belt 15 is removed by the filming layer removing means.

The contact member composed of the roller 19 may also have such a function of removing the filming layer. In this case, the filming layer removing member 24 becomes unnecessary and the structure of the image forming apparatus is further improved. It can be simplified and is advantageous in terms of cost.

By the way, the roller 19 and the intermediate transfer belt 1
If there is a residual potential on the surface of the roller 19 at the time of contact with the roller 5, it may not be possible to accurately detect the potential for detecting the toner filming layer.
Therefore, as illustrated in FIG. 4, when the static eliminating member 26 for static eliminating the roller surface is brought into contact with the surface of the roller 19, the residual potential on the surface of the roller 19 can be removed through the static eliminating member 26. it can.

Toner, dust, and other foreign matter are easily attached to the surface of the roller 19. Therefore, when the cleaning member 27 is brought into contact with the surface of the roller 19 and the roller 19 is rotated, the attached matter is removed. Can be cleaned. However, when such a cleaning member is brought into contact, it and the roller 1
There is a risk that electric charges may remain on the roller surface due to frictional charging with the roller 9. In such a case, the charge removing member 26 is provided downstream of the cleaning member 27 in the rotation direction of the roller 19.
Is provided, this can remove such charges.

In the example shown in FIG. 4, since the static elimination member 26 is composed of a blade made of a conductive material that is grounded, the static elimination member 2
6 also has a function of cleaning the roller 19, and a dedicated cleaning member 27
Is unnecessary, the configuration of the image forming apparatus can be simplified, and it is advantageous in terms of cost.

As described above, when there is a residual potential on the surface of the roller 19 when the roller 19 and the intermediate transfer belt 15 are in contact with each other, the potential for detecting the filming layer or the like is accurately determined. It may not be able to be detected. For the same reason, it is not preferable that the residual potential exists on the surface of the intermediate transfer belt 15. Therefore, FIG.
As shown in, when the neutralization means of the intermediate transfer belt 15 is provided on the upstream side in the running direction of the intermediate transfer belt 15 with respect to the contact portion between the intermediate transfer belt 15 and the roller 19,
Such residual potential can be removed.

The static elimination corona discharger 30 connected to the AC corona discharge power source 28 (FIG. 4) is an example of the static elimination means, and the above-mentioned residual potential can be removed by the discharge.

Further, in this example, since the intermediate transfer belt 15 is a medium resistance body, as shown in FIG. 4, the driven roller 8 facing the roller 19 and in contact with the intermediate transfer belt 15 is made conductive and is grounded. By doing so, the electrostatic charge on the intermediate transfer belt 15 can be removed through the driven roller 8 (see also FIG. 6). In this case, the roller 8 constitutes a charge eliminating means for the intermediate transfer belt 15, and the charge eliminating means is provided in the area of the contact portion between the intermediate transfer belt 15 and the roller 19.

The structure in which the contact member composed of the above-mentioned roller is cleaned by the cleaning member, or the intermediate transfer belt 15 is used.
The configuration in which the electricity is removed by the electricity removing means can be applied to each of the embodiments described later.

In the embodiment shown in FIGS. 5 and 6,
The contact member for detecting the toner filming layer on the intermediate transfer belt 15 is not an insulating material but a medium resistance contact member.

The medium-resistance contact member 29 shown in FIG. 5 is integrally supported around a conductive support member (core bar) 31, and the whole constitutes a roller 32, which is attached to the intermediate transfer belt 15. It is supported so that it can be moved freely.

The medium resistance contact member 39 shown in FIG. 6 is composed of a brush supported around a conductive support member (core bar) 41, which constitute a brush roller 42, which is an intermediate transfer belt 15. It is supported so that it can be moved toward and away from.

As the material of the medium resistance contact members 29 and 39, 10 ⁵ in which conductive fine particles or the like are dispersed in an insulating material is used.
A material having a resistivity of 10 ⁸ Ω · cm is desirable. When the medium resistance contact members 29 and 39 having the above-described configuration are used, after separating them from the intermediate transfer belt 15,
The charges remaining in the insulating portions of the medium resistance contact members 29, 39 move to the conductive support members 31, 41 through the conductive portions (conductive fine particles) of the same member. At this time, the medium resistance contact members 29 and 39 are in an electrically floating state. In this state, the potential detecting device 21 detects the potential of the same potential portion (potential measuring portion) 33 as the supporting members 31 and 41. If the toner filming layer is not present on the surface of the intermediate transfer belt 15 or if the toner filming layer is relatively slight, the detected value of the potential by the potential detecting device 21 becomes large, and the filming layer is not formed. If it is formed significantly, the detected value becomes small.

As described above, when the medium resistance contact members 29 and 39 in contact with the intermediate transfer belt 15 are separated from the belt 15, immediately after the separation, the potentials of the supporting members 31 and 41 are changed. The potential is detected by the potential detecting means including the potential detecting device 21, and the detected value is compared with the predetermined reference value by the comparing means. Based on the comparison result, the intermediate value is obtained in the same manner as in the previous embodiment. The presence or absence of the toner filming layer on the transfer belt 15 can be detected,
The filming layer can be removed.
According to this configuration, in order to detect the potentials of the contact members 29 and 39, it is not necessary to rotate them, and the potential can be easily detected.

The other configurations of the embodiment shown in FIGS. 5 and 6 are the same as those of the embodiment described above with reference to FIGS. 1 to 4. Further, also in the embodiment shown in FIGS. 5 and 6, as a means for removing the toner filming layer,
The filming layer removing member 24 as shown in FIG. 1 can be used, and the toner filming layer on the intermediate transfer belt 15 can be removed by the contact members 29 and 30 having medium resistance. At that time, since the contact member 39 shown in FIG. 6 is made of a brush, the contact film 39 can efficiently remove the toner filming layer.

Further, foreign matter such as toner or paper dust adheres to the contact member 39 composed of a brush. In particular, when the contact member 39 also serves as the filming layer removing means, foreign matter is likely to adhere to the contact portion.

Therefore, as shown in FIG. 6, a flicker member 34 is provided which is brought into contact with the contact member 39 made of a brush of medium resistance fiber and brought into contact with the contact member 39, and the brush roller 42 is rotated to allow the flicker member 34 to contact the contact member 39. It is preferably configured to remove deposits. At this time, in order to prevent frictional charging of the brush and leakage of the charging charge by the flicker member 34, it is desirable that the flicker member 34 is made of the same material as the brush of the contact member 39. Further, in this case, since the flicker member 34 is composed of a medium resistance body, if the grounding of the flicker member 34 may cause a charge for detecting the filming layer to leak to the ground side, the flicker member 34 is electrically floated. It is advantageous to prevent the occurrence of such leak.

Here, FIGS. 7 and 8 show the measurement results of the charging potential of the contact member 39, which was carried out by the structure shown in FIG. FIG. 7 shows the medium resistance contact member 39 shown in FIG.
That is, it shows an example of the correlation characteristic between the elapsed time after the brush is separated from the intermediate transfer belt 15 and the potential of the support member 41 which is the brush core metal. That is, it shows the change with time of the potential generated in the support member 41 when the brush is separated. The measurement results shown in FIGS. 7 and 8 are obtained when a loop brush made of carbon-containing acrylic fiber (trade name: SA-7 Toray Co., Ltd.) is used as the contact member 39 of medium resistance, and the following specification conditions are set. belongs to.

(1) The loop brush is 360D / 24
F, 600 loops / inch ² , and bristle length of 4.5 mm, the outer diameter of the brush roller 42 was 18 mm, and the outer diameter of the support member (core metal) 41 was 9 mm. (2) The biting amount was set so that the brush contact nip width when contacting the intermediate transfer belt was 9 mm. (3) As the intermediate transfer belt, a medium resistance intermediate transfer belt having a carbon-containing ethylene tetrafluoroethylene as a main component and a thickness of 150 μm was used. The contact operation of the contact member 39 with the intermediate transfer belt 15 was performed by a solenoid.

In FIG. 7, the potential of the support member 41 when the contact member 39 is in contact with the intermediate transfer belt 15 is 0.
V, the initial potential V ₀ at the same time as the contact member 39 is separated.
Occurs and then decays exponentially (solid line in the figure). The present invention utilizes the phenomenon that the initial potential V ₀ changes with the change of the surface condition of the intermediate transfer belt, that is, the change of the filming layer formation degree.

The charging potential of the contact member 39 is measured by the periodic contact / separation operation of the contact member 39 made of a brush, and the toner filming on the belt surface is determined from the decrease (or increase) of the initial potential V ₀ value. When the increase of the layer is detected, the filming layer removing operation is performed by the belt polishing action of the filming layer removing means described above. Also,
It is also possible to control the removal operation by detecting the V ₀ value after or during the removal operation. In this way, by using the contact member 39 shown in FIG. 6 as the filming layer removing means, the filming layer can be efficiently removed with a simple structure.

FIG. 8 shows the sliding contact time of the brush (contact member 39) with respect to the intermediate transfer belt when the medium resistance contact member 39 is used as the filming layer removing means, and the above V.
An example of measurement with ₀ (detection potential immediately after separation) value is shown. That is, it shows how the V ₀ value changes as the brush rubbing time elapses with respect to the intermediate transfer belt 15 on which the toner filming layer is formed. In the figure, the solid line is a measurement example when the brush is rotated at 900 rpm, the two-dot chain line is a measurement example when the brush is rotated at 600 rpm, and the broken line is the measurement example when the brush is rotated at 300 rpm. This is a measurement example. That is, the characteristic line is shown when the filming layer removal capacity (filming layer polishing capacity) is changed.

In the figure, Vn is the intermediate transfer belt 1.
5 is the detected potential value when the product is new, and is the detected potential value when the filming layer of toner is not formed (generated). When the toner filming layer is removed, the value of the detected potential (initial potential) V ₀ immediately after the contact member 39 is separated from the intermediate transfer belt 15 increases to the plus side. This increase rate reflects the toner filming removal ability (polishing ability), and the rubbing ability of the brush can be measured by the present invention. When the filming layer is completely removed, V ₀ becomes constant (Vn).

Therefore, as described above, when the initial potential V ₀ becomes equal to or lower than the predetermined reference value Vs, the filming removal operation is performed, and V ₀ is the value when the belt is new. To finish the removal operation when returning to Vn,
When the operation is controlled by the control circuit, the filming removal can be performed in the optimum operation time.

If the brush is rubbed against the intermediate transfer belt for a long period of time, the deterioration of the intermediate transfer belt may be accelerated and the life of the intermediate transfer belt may be shortened. If so, such early deterioration can be suppressed and the life of the intermediate transfer belt can be extended.

By the way, the intermediate transfer belt 15 used in each of the above-described embodiments has a main component made of a polymer material. For example, as described above, carbon-containing fluororesin such as carbon-containing ethylene tetrafluoroethylene (relative dielectric constant ε ₁
≒ 2). Further, the contact member 39 shown in FIG.
Similarly, the main component is also made of a polymer material, for example, a carbon-containing acrylic resin (relative permittivity ε ₁ ≈3), and its form is, for example, a loop brush.

Therefore, depending on these material conditions, the intermediate transfer belt 15 is negatively charged, and the brush 42 is positively charged. In the present invention, the materials of both are not limited to the above materials, but the larger the difference in the specific electric current between the two is, that is, the farther the relationship between the two in the triboelectric charging series is, the larger the potential is detected. be able to. In particular, it is desirable that the difference in relative permittivity between the two is 0.5 or more.

The brush material is not limited to an acrylic resin as long as it satisfies the above conditions, but an acrylic material having a relatively high hardness is preferable as a characteristic of the rubbing member, and such a brush is used. If the contact member 39 is used, the toner filming layer can be efficiently removed.

Here, when the toner filming layer is formed on the surface of the intermediate transfer belt 15, microscopically, as shown in FIG. 9A, the contact member 39 composed of the intermediate transfer belt and the brush. Directly contact the toner component T
And a portion in contact with the contact member (brush) 39. In this example, since the polyester resin (relative dielectric constant ε ₁ ≈3) is used as the main component of the toner, the toner component T
It is difficult for charge to move in the contact portion between the contact member 39 and the contact member 39, and charge transfer occurs only in the contact portion with the contact member (FIG. 9A). Therefore, the contact member 39 and the intermediate transfer belt 1
The potential V ₀ generated at the time of separation of 5 becomes relatively small. On the other hand, in the state where the toner component is not attached, the substantial contact area between the intermediate transfer belt and the contact member 39 increases, so that the amount of moving charges also increases (FIG. 9B),
As shown in FIG. 8, the potential V ₀ after the separation also increases to the positive side.

By the way, in each of the above-mentioned embodiments, when the humidity in the vicinity of the intermediate transfer belt and the contact member is changed, the amount of water adsorbed on the contact member and the surface of the belt and the amount of backflow charge when separating them are changed. The potential V ₀ immediately after the contact member is separated also changes. In addition, the potential decay after contact member separation is caused mainly by the charge leakage into the air, so it depends on the humidity of the atmosphere, and the charging half-time seems to decrease exponentially as the relative humidity increases. become. The broken line in FIG. 7 shows how the potential of the support member (core metal) 41 of the contact member 39 made of the brush shown in FIG. 6 changes with time when the humidity rises. Immediately after the separation, the potential V ₀ decreases and the decay rate increases.

As described above, the potential of the supporting member (core metal) 41 changes depending on the environmental conditions even with the intermediate transfer belt in the same toner filming state. Therefore, as illustrated in FIG. 6, the humidity detecting sensor 35 is provided in the vicinity of the contact member 39 made of a brush, and the reference values Vs and Vn described above are shifted according to the detected value. That is, according to the detection value of the sensor 35, the reference value Vs of the comparison means is corrected by the correction means (not shown). For example, when the humidity becomes high, the reference value Vs is corrected so that it becomes smaller than before.

When the temperature changes and the change in the potential of the supporting member of the contact member with time changes, such a correction can be performed by similarly providing a temperature detection sensor in the vicinity of the contact member.

In any case, by correcting the reference value Vs according to the difference in the environmental conditions around the brush, even if such environmental conditions change, the conditions for removing the toner filming layer and the residual toner at the time of cleaning It is possible to set optimal removal conditions and transfer conditions. Note that the relationship between the detected value such as humidity and temperature and the shift amount between the reference value and each other can be experimentally grasped in advance, and by inputting those data values into a predetermined memory circuit, it is possible. Can achieve the purpose of the period.

The configuration relating to the humidity or temperature detecting sensor described above can be applied to each of the above-described embodiments.

It should be noted that it is also possible to detect the change in environmental conditions in reverse by utilizing the potential decay process as shown in FIG. In FIG. 6 and FIG. 7, the support member 41 after a certain time has passed since the contact member 39 was separated from the intermediate transfer belt 15.
Let Vt be the potential of the potential of ΔV (= V ₀ −V
t) increases with increasing humidity. Therefore, the humidity can be detected from the magnitude of the change amount ΔV, and these can be shifted so that the reference values Vs and Vn described above are corrected according to the change amount ΔV. That is,
Immediately after the intermediate transfer belt 15 and the contact member 39 are separated from each other,
Provided is a potential change detection means (not shown) for comparing the detection value of the potential detection means with the detection value after a fixed time to detect the potential detection change amount, and according to the potential change amount, the reference value described above is provided. The Vs is corrected by the correction means. The relationship between the variation ΔV and the shift amount of the reference value can also be experimentally obtained in advance, and the intended purpose can be achieved by inputting these data into a predetermined storage circuit. In this case, it is not necessary to newly provide the humidity detection sensor 35 (FIG. 7), the temperature detection sensor, and the like.

It goes without saying that the configuration relating to the correction of the reference value described above can also be applied to each of the embodiments described above.

In the embodiment described above, the contact members 19,
The presence or absence of the filming layer on the intermediate transfer belt 15 is detected by 29 and 39, and the filming layer removing operation is controlled by the control means according to the result, but based on the detection result by the contact member. Alternatively, the output voltage of the transfer unit for transferring the toner image may be controlled as follows.

The paper transfer roller 13 shown in FIG.
A bias voltage power supply E ₂ applies a bias voltage having a polarity opposite to that of the toner on the intermediate transfer belt 15 to transfer the toner image on the intermediate transfer belt 15 to the recording medium 16. An example of a transfer unit for transferring the toner image on the body is configured.

Here, as described above, when the filming layer is formed on the surface of the intermediate transfer belt 15, the transfer efficiency of the toner image by the above-mentioned paper transfer roller 9 is lowered, and thereby the image is formed. Quality is reduced.

Therefore, the aforementioned contact members 19, 29, 3
9. When it is detected by the potential detecting means, the comparing means, etc., that the toner filming layer is formed on the intermediate transfer belt 15 to lower the transfer efficiency, the paper transfer roller 13 is driven by the power supply E _2. It is possible to prevent the transfer efficiency from decreasing by shifting the voltage value to be applied to and setting it to the optimum voltage value. For example, when the filming layer is formed on the intermediate transfer belt 15, the bias voltage applied to the paper transfer roller 13 is set higher than before, and the decrease in transfer efficiency is prevented. In this way, based on the comparison result by the comparison means for comparing the detection value by the aforementioned potential detection means and the predetermined reference value,
A control unit (not shown) can control the output of the transfer unit including the paper transfer roller 13 and prevent a decrease in transfer efficiency. At this time, the relationship between the detected value V ₀ and the shift amount of the transfer voltage value is experimentally obtained in advance,
This is input to the memory circuit.

As described above, the present invention can also be applied to an image forming apparatus having a latent image carrier such as the photoconductor 1 shown in FIG. 3 as a carrier, and the toner filming layer on the photoconductor 1 can be applied. The presence / absence of the toner can be detected by the above-described configurations. In this case, the belt transfer roller 5 illustrated in FIG. 3 is an example of a transfer unit for transferring the toner image on the carrier. Constitute. That is, the transfer roller 5 is applied to the photoconductor ₁ by the bias voltage power source E 1.
A voltage having a polarity opposite to that of the upper toner is applied to transfer the toner on the photoconductor 1 onto the intermediate transfer belt 15. In this case as well, the magnitude of the bias voltage for the paper transfer roller 9 was controlled. The magnitude of the bias voltage applied to the belt transfer roller 5 can be controlled in the same manner as described above. That is, based on the comparison result by the comparison means for comparing the detection value of the potential detection means and the predetermined reference,
When it is detected that a filming layer that reduces the transfer efficiency is formed on the photoconductor 1, the control unit controls the output of the transfer unit including the belt transfer roller 5. Also in this case, the bias voltage applied to the belt transfer roller 5 may be increased to prevent the transfer efficiency from decreasing.

The structure for controlling the output of the above-mentioned transfer means is also applicable to each of the above-mentioned embodiments, but this structure removes the filming layer by slidingly contacting a carrier such as the intermediate transfer belt 15. It is also applicable to the case where the filming layer removing means is not provided. This is because it is possible to prevent the transfer efficiency from being lowered by the transfer means without removing the filming layer.

[0090]

According to the image forming apparatus of the present invention, it is possible to detect the toner filming layer, which has been difficult to detect in the past, and to remove such residual toner and toner filming layer. It becomes possible to remove under optimum conditions.

According to the image forming apparatus of the second aspect,
In addition to the advantages described above, the potential of the contact member can be easily detected.

According to the image forming apparatus of the third aspect,
It is also possible to omit the dedicated filming layer removing means, which can simplify the configuration of the image forming apparatus and is advantageous in terms of cost.

According to the image forming apparatus of the fourth and fifth aspects, the optimum transfer conditions can be set according to the degree of formation of the filming layer, and even when the filming layer removing means is not provided, It is possible to always obtain stable and high-quality images.

According to the image forming apparatus of the sixth aspect,
The contact member can clean and remove deposits on the surface of the roller body, which is a contact member, and can also remove charges on the surface of the roller body caused by the contact member. The electric potential can be accurately detected.

According to the image forming apparatus of claim 7,
It is possible to remove deposits adhering to the brush roller, which is a contact member, and to effectively prevent leakage of charges for detecting the filming layer. In particular, the contact member constitutes the filming layer removing means. It is effective when done.

According to the image forming apparatus of claim 8,
The charges remaining on the carrier can be removed, and the filming layer on the surface of the carrier can be detected accurately.

According to the image forming apparatus of claim 9,
Even if the humidity condition changes, the filming layer removal condition and the transfer condition can always be optimally set.

According to the image forming apparatus of the tenth aspect, it is possible to cope with environmental changes without providing a humidity sensor or the like.

According to the image forming apparatus of the eleventh aspect, the degree of formation of the filming layer can be detected more accurately.

[Brief description of drawings]

FIG. 1 is a diagram showing only a main part of a potential detecting component of a contact member included in an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing a state in which the contact member is placed at a potential detection position.

FIG. 3 is a schematic configuration diagram of an electrophotographic image forming apparatus according to an embodiment of the present invention.

FIG. 4 is a diagram showing an example in which a cleaning member, a charge removing member, and the like are arranged around a contact member.

FIG. 5 is a diagram showing another example of a contact member potential detection component.

FIG. 6 is a view showing a contact member potential detection component of another example.

FIG. 7 is a diagram showing changes over time in the magnitude of the brush core metal potential after the brush, which is a contact member, is separated from the intermediate transfer belt.

FIG. 8 is a diagram showing how the initial potential changes with the lapse of time when a contact member made of a brush rubs the intermediate transfer belt.

FIG. 9 is a diagram for explaining a potential forming state at a contact interface between a contact member made of a brush and an intermediate transfer belt, depending on whether toner is present or not.

[Explanation of symbols]

 6 Cleaning Device 11 Cleaning Device 19 Roller 19A Part 26 Static Eliminator Member 27 Cleaning Member 29 Contact Member 31 Support Member 32 Roller 34 Flicker Member 35 Humidity Detection Sensor 39 Contact Member 41 Support Member

Claims (11)

[Claims] 1. A carrier for carrying a toner image or a recording medium as a carried object, which is driven so that the carried object is conveyed, and a toner and other adhering substances remaining on the carrying body. When the cleaning device for removing, the insulating contact member that can be brought into contact with and separated from the carrier, and the insulating contact member that is in contact with the carrier are separated from the carrier, Immediately after this separation, a potential detecting means for detecting the surface potential of the insulating contact member portion brought into contact with the carrier, and a comparing means for comparing a detection value by the potential detecting means with a predetermined reference value, An image forming apparatus comprising: a filming layer removing unit that removes the toner filming layer formed on the surface of the carrier based on the comparison result by the comparing unit. 2. A carrier which carries a toner image or a recording medium as a carried object and is driven so that the carried object is conveyed, and a residual toner and other adhering substances on the carrier are removed. And a medium resistance contact member supported by a conductive support member, and a medium resistance contact member in contact with the carrier. When separated from the body, immediately after the separation, a potential detection means for detecting the potential of the support member, a comparison means for comparing the detection value by the potential detection means with a predetermined reference value, and the comparison means An image forming apparatus comprising: a filming layer removing unit that removes a toner filming layer formed on the surface of the carrier based on a comparison result. 3. The image forming apparatus according to claim 1, wherein the contact member also serves as the filming layer removing unit. 4. A carrier which carries a toner image or a recording medium as a supported object and is driven so that the supported object is conveyed, and a transfer means for transferring the toner image on the carrier. A cleaning device that removes the toner and other adhered substances remaining on the carrier after the transfer, an insulating contact member that can freely contact and separate from the carrier, and contact the carrier. When the insulating contact member in the opened state is separated from the carrier, immediately after this separation, a potential detecting means for detecting the surface potential of the insulating contact member portion brought into contact with the carrier and the potential detecting means. An image forming apparatus comprising: a comparison unit that compares a detection value of the detection unit with a predetermined reference value; and a control unit that controls the output of the transfer unit based on the comparison result of the comparison unit. . 5. A carrier for carrying a toner image or a recording medium as a carried object and being driven so that the carried object is conveyed, and a transfer means for transferring the toner image on the carrying body. And a cleaning device for removing residual toner and other adhered substances on the carrier after the transfer, and a medium resistance contact member supported by an electrically conductive support member so as to be contactable with and separable from the carrier. When the medium resistance contact member that is in contact with the carrier is separated from the carrier,
Immediately after this separation, the potential detection means for detecting the potential of the supporting member, the comparison means for comparing the detection value by the potential detection means with a predetermined reference value, and the comparison result by the comparison means, based on the comparison result, An image forming apparatus comprising: a control unit that controls an output of a transfer unit. 6. The contact member comprises a rotatable roller body, a cleaning member for cleaning the surface of the roller body, and a roller body provided downstream of the cleaning member in the rotational direction of the roller body. A static elimination member for surface static elimination is provided.
The image forming apparatus according to any one of items 1 to 5. 7. The medium resistance contact member is composed of a brush made of medium resistance fiber, and the flicker member electrically floated is brought into contact with the brush.
The image forming apparatus according to item 1. 8. A contact portion between the carrier and the contact member,
Or, on the upstream side in the moving direction of the carrier with respect to this contact portion,
8. A charge removing means for a carrier is provided, according to claim 1.
The image forming apparatus described in 1. 9. A humidity detecting sensor for detecting humidity in the vicinity of the contact member, and a correcting means for correcting the reference value according to a detected value of the sensor. The image forming apparatus according to item 1. 10. A potential change detecting means for detecting the amount of potential change by comparing the detected value of the potential detecting means immediately after the supporting member and the contact member are separated from each other and the detected value after a predetermined time, and the potential change detecting means. The image forming apparatus according to claim 1, further comprising a correction unit that corrects the reference value according to a potential change amount. 11. The carrier and the contact member are composed of a polymer material as a main component of the material constituting the both, and the difference in relative dielectric constant between the main component of the carrier and the main component of the contact member is 0. The image forming apparatus according to claim 1, wherein the number is 5 or more.