JP2005172857A - Image forming apparatus and transfer stripping device used for the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To effectively prevent an image defect caused by a current leaked into a destaticizing device in an embodiment where a contact transfer member and the destaticizing device are provided. <P>SOLUTION: A transfer stripping device 2 includes: the contact transfer member 4 which sandwiches a transfer material 3 in a transfer area between an image carrier 1 and the member 4 itself and electrostatically transfers an image on the image carrier 1 to the transfer material 3; the destaticizing device 5 which is disposed downstream of the contact transfer member 4 in the direction in which the transfer material is conveyed, and destaticizes the transfer material 3 in the course of the passage of the transfer material; and a destaticization control means 6 by which supply of power to the destaticizing device 5 is controlled and supply of power to the destaticizing device is stopped when the transfer material 3 to be passed through the transfer area has a high probability of high moisture content. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus such as a copying machine or a printer, and in particular, an image effective in an aspect provided with a contact transfer unit and a static eliminator in which a transfer material is sandwiched in a transfer region between the image carrier and the image carrier. The present invention relates to an improvement of a forming apparatus and a transfer peeling apparatus (contact transfer member + static eliminator) used therein.

Conventionally, as an example of this type of image forming apparatus, for example, an electrophotographic system, an image carrier such as a photosensitive drum carrying an image, and an image on the image carrier are transferred to a transfer material and an image carrier. A device provided with a transfer peeling device for peeling the transfer material from has already been provided.
As a typical embodiment of this type of transfer peeling apparatus, a transfer device that electrostatically transfers a toner image formed on an image carrier onto a transfer material, and a transfer device that is disposed downstream of the transfer material in the transfer material conveyance direction, and There is known a device provided with a static eliminator that neutralizes the transfer material when passing through the transfer material (see, for example, Patent Documents 1 to 5).
Here, as the transfer device, there is a non-contact type device such as corotron, but from the viewpoint of suppressing the generation of ozone and the like, a transfer roll that holds a transfer material in a transfer area between the image carrier and the like. Such contact type devices are often used.
On the other hand, as a static eliminator, a corotron, a static eliminator (DTS: Detach Saw) and the like are widely used.

Japanese Patent Laid-Open No. 1-269969 (Example, FIG. 1) JP-A-2-264985 (Description of Examples, FIG. 2) JP 2001-228718 A (Embodiment of the Invention, FIG. 1) JP 2002-123115 A (Embodiment of the Invention, FIG. 2) Japanese Patent Laid-Open No. 11-258944 (Embodiment of the Invention, FIG. 1)

By the way, as this type of transfer peeling apparatus, for example, a transfer roll to which a transfer bias is applied and controlled at a constant current, and a static eliminator (for example, a static elimination needle) to which a neutralization bias having a polarity opposite to the transfer bias is applied are used. This is a technique that has been used for single-component toners (low-charge (low-tribo) toners), but in recent years, polymerized toners that are desired to be used in color image forming apparatuses and high-speed black-and-white image forming apparatuses. There is an increasing demand to adopt (highly charged (high tribo) toner).
However, when the above-described transfer peeling device is used for the use model of the highly charged toner, when the transfer material is water-containing paper, there is a technical problem that image defects such as white spots and toner scattering are likely to occur. It was issued.

More specifically, in a conventional transfer peeling apparatus, a high humidity environment (for example, temperature 28 ° C./humidity 85%) / low charged toner (7 μC / g) / water-containing paper (4024 paper 11 ″ × 17 ″ 9.6) Even if power is supplied to the transfer roll and the static eliminator under the use condition of “% seasoning paper”, as shown in FIG. 24, a good current region exists as the transfer current, and the transfer latitude can be secured.
On the other hand, in the same conventional transfer peeling apparatus, high humidity environment (for example, temperature 28 ° C./humidity 85%) / highly charged toner (25 μC / g) / water-containing paper (4024 paper 11 ″ × 17 ″ 9.6% seasoning) When the power is supplied to the transfer roll and the static eliminator under the usage condition of (paper), as shown in FIG. 25, there is almost no good current region as the transfer current, white spots and toner scattering are observed, and transfer latitude is ensured. Is extremely difficult.

The inventor analyzed the technical problem described above, a part of the transfer current flowing through the transfer roll flows into the static eliminator through the water-containing paper as a leakage current, and the effective transfer current is insufficient. It was found that this resulted in transfer failure.
As a countermeasure for solving such a technical problem, for example, as shown in Patent Document 2, the neutralization bias to the static eliminator is made variable according to the environmental condition or the image forming condition, so that the occurrence of a transfer defect can be prevented. Proposals have been made to prevent this.
However, with this measure, the static elimination bias of the static eliminator must be switchable, which not only increases the cost of the apparatus, but also changes that occur during the transfer operation (for example, changes in environmental conditions or transfer after peeling) (Gap change between transfer material and static eliminator accompanying change in material posture) cannot be handled.
Further, as another countermeasure for solving the above technical means, for example, as shown in Patent Documents 3 and 4, for example, a large resistance is provided in a power supply path of a static elimination needle as a static eliminator, and leakage current is caused by this resistance. Proposals have been made to suppress it.
However, in a mode in which a large resistance is simply provided, it is still insufficient to improve image defects in a model using a highly charged toner having a high charge amount.

Further, a fixing device (for example, a heat and pressure fixing roll method) is often disposed on the downstream side of the transfer peeling device in the transfer material conveyance path. For example, as shown in Patent Document 5, fixing is performed. There has already been proposed a mode in which a fixing bias having the same polarity as the transfer bias is applied to the pressure roll of the apparatus.
According to this aspect, even when the transfer material is water-containing paper, for example, when the toner image is fixed on the transfer material, the bubbles in the transfer material expand rapidly just before the fixing area in the fixing device. It is preferable in that the phenomenon that the toner on the surface of the transfer material is scattered can be suppressed.
However, in this embodiment, since a bias having the same polarity as the transfer bias is applied as the fixing bias, if a neutralizing bias having a reverse polarity is applied to the static eliminator during the transfer operation, the fixing current associated with the fixing bias of the fixing device is reduced. A part leaks to the static eliminator side, which causes image defects due to fixing failure by the fixing device.

  The present invention has been made in order to solve the above technical problem, and in an aspect including a contact transfer member and a static eliminator, to effectively prevent image defects due to a leakage current to the static eliminator. An image forming apparatus and a transfer peeling apparatus used for the image forming apparatus are provided.

  That is, according to the present invention, as shown in FIG. 1, an image carrier 1 that carries an image, an image on the image carrier 1 is transferred to a transfer material 3, and the transfer material 3 is peeled from the image carrier 1. In the image forming apparatus provided with the transfer peeling device 2, the transfer peeling device 2 holds the transfer material 3 in the transfer area between the image carrier 1 and the image on the image carrier 1 is transferred to the transfer material 3. A contact transfer member 4 to be electrostatically transferred, a static eliminator 5 disposed downstream of the contact transfer member 4 in the transfer material conveyance direction and neutralizing the transfer material 3 when passing through the transfer material, and power supply control for the static eliminator 5 are provided. And a static elimination control means 6 for stopping the power supply to the static eliminator 5 under a high moisture content condition with high probability that the transfer material 3 passing through the transfer zone has a high moisture content. Is.

In such technical means, the present application is directed to an image forming apparatus including the image carrier 1 and the transfer peeling device 2 (contact transfer member 4 + static eliminator 5).
Here, the image carrier 1 may be in the form of a belt that is stretched around a stretch roll in addition to the drum shape. In addition to an image forming carrier such as a photoconductor, an intermediate transfer member is also included.
Further, the contact transfer member 4 is only required to sandwich the transfer material 3 in the transfer area between the image carrier 1 and is normally placed in contact with the image carrier 1, but is placed close to the image carrier 1. It does not matter. The contact transfer member 4 typically includes a transfer roll, but also includes a transfer belt stretched around a stretch roll.
A predetermined transfer bias Vt is applied to the contact transfer member 4 by the transfer control means 7. In this case, the transfer control means 7 may be appropriately controlled. However, the contact transfer member 4 is preferably subjected to constant current control by the transfer control means 7. In this way, when performing constant current control, if there is a leakage current in the static eliminator 5, the transfer condition is likely to be affected, so the present application is particularly effective.

In addition, an image material such as toner is used for the image on the image carrier 1, and the charging characteristics of the image material are arbitrary. However, when a high tribo image material is used, a low tribo image material is used. Since a higher transfer voltage (current) is necessary, the technical problem of the present application (transfer failure due to leakage current to the static eliminator 5) is likely to occur. In this regard, the present application is particularly effective when a high tribo image material is used because the transfer failure associated with the leakage current to the static eliminator 5 can be improved. The high tribo image material here refers to a material having a charging characteristic of 10 to 40 μC / g under a high humidity environment (for example, temperature 28 ° C./humidity 85%). The low tribo image material refers to a material having charging characteristics of 3 to 10 μC / g under a high humidity environment.
Further, the present application is particularly effective because the average particle diameter of the image material is a small diameter of 8 μm or less, and the non-magnetic toner as the image material easily leads to high tribo.

The static eliminator 5 typically includes a static elimination needle, but also includes a corotron or other static elimination device. And as a preferable aspect of the static eliminator 5, what has connected 50-1000 Mohm high resistance in series to the electric power feeding path | route is mentioned. In this case, it is preferable for suppressing the leakage current to the static eliminator 5.
Furthermore, the static elimination control means 6 should just perform the function which stops the static eliminator 5 on high moisture content conditions on the assumption that normal electric power feeding control with respect to the static eliminator 5 is performed.
Here, the “high moisture content condition” refers to a condition with high probability regardless of whether or not the transfer material 3 actually has a high moisture content. In the case of “on the first surface transfer”. Note that the present application also includes control for measuring the moisture content of the transfer material 3 with a moisture content sensor or the like and stopping the operation of the static eliminator 5 if the moisture content is equal to or higher than a predetermined level.

Further, when the condition “when transferring the first surface of the transfer material 3 in a high humidity environment” is used as the high water content condition, the static elimination control unit 6 determines whether or not the environment is a high humidity environment. It is preferable to include means 8 and transfer surface discriminating means 9 for discriminating whether the transfer surface of the transfer material 3 is the first surface or the second surface.
Here, as a typical aspect of the environment discriminating means 8, there is one that discriminates whether or not the environment is a high humidity environment based on information from an environmental sensor for process control. In this aspect, the environmental sensor is typically a humidity sensor, but it is preferable to use this in combination with a temperature sensor.
Further, as another representative aspect of the environment discriminating means 8, there is one that discriminates whether or not the environment is a high humidity environment based on the environmental dependence of the contact transfer member 4 made of an ion conductive material. . The contact transfer member 4 made of an ion conductive material greatly changes its resistance according to the environmental change and has a large environmental dependency. Therefore, if this is used, the environmental change can be grasped.

Further, as a representative aspect of the static elimination control means 6, the static eliminator 5 has a static elimination member 5a to which the static elimination bias Vd is applied, and the static elimination control means 6 controls the static elimination bias Vd at a constant voltage. If constant voltage control is performed, it is preferable in that a constant discharge start voltage can be applied and the static elimination action can be effectively exhibited.
A more preferable aspect of the static elimination control means 6 is one in which the static elimination bias Vd is controlled at a constant voltage and switched to constant current control under a condition that exceeds a predetermined current value. Switching to constant current control may be performed by, for example, a current limiter. According to this aspect, it is preferable in that the discharge start is surely performed and the static elimination action is made uniform.

As described above, according to the model of the present invention shown in FIG. 2A, when the transfer material 3 satisfying the high water content condition passes through the transfer area between the image carrier 1 and the contact transfer member 4, the static elimination is performed. Since the controller 6 (see FIG. 1) stops the static eliminator 5, a part of the transfer current It from the contact transfer member 4 does not flow into the static eliminator 5 as a leakage current ΔIt, and the transfer current It is image-carrying. The image is surely injected into the body 1, and the image on the image carrier 1 is reliably transferred to the transfer material 3.
On the other hand, in the comparative model shown in FIG. 2B, the static eliminator 5 is operated as it is when the transfer material 3 that satisfies the high water content condition passes through the transfer area between the image carrier 1 and the contact transfer member 4. However, according to this comparative model, a part of the transfer current It from the contact transfer member 4 flows into the static eliminator 5 side as a leakage current ΔIt, so that the transfer current It injected to the image carrier 1 side is insufficient. Therefore, image defects associated with insufficient transfer current tend to occur accordingly.

Further, in the case of using the condition “during the transfer of the first surface of the transfer material 3 in a high humidity environment” as the high water content condition, the charge removal control means 6 is configured to be high under the condition that the transfer material 3 is an OHP sheet. It is preferable that the static eliminator 5 is operated even when the first surface of the transfer material 3 is being transferred in a wet environment. This is because when the transfer material 3 is an OHP sheet, the high water content condition is not achieved, and there is no problem in operating the static eliminator 5.
Furthermore, as a high moisture content condition, the condition “when transferring the first surface of the transfer material 3 in a high humidity environment” is used. In addition, in a mode in which a heater is provided in the transfer material supply tray, Under the condition that the heater (tray heater) of the material supply tray is operating, it is preferable to operate the static eliminator 5 in the high humidity environment, even when the first surface of the transfer material 3 is being transferred. . When the tray heater is in an operating state, even if the tray material is in a high humidity environment, the transfer material 3 accommodated in the transfer material supply tray is heated by the heater. This is because there is no problem in operating the static eliminator 5. In this case, on / off of the tray heater may be interlocked with an environmental sensor, or may be in response to an operation by SE or the like.

Further, the present invention is also effective for a structure for preventing an image scattering phenomenon that occurs between the “charger 5 and the fixing device 10”.
That is, a fixing device 10 is provided on the downstream side of the static eliminator 5 in the conveying direction of the transfer material 3. If the fixing member 11 to which is applied is provided, image scattering is effectively prevented by the presence of the fixing bias.
At this time, even if the transfer material 3 is water-containing paper, since the static eliminator 5 stops, current leakage from the fixing member 11 to the transfer material 3 (water-containing paper) → static eliminator 5 can be effectively prevented.

Further, the present invention is not limited to the image forming apparatus described above, but also targets a transfer peeling apparatus used for this.
In this case, as shown in FIG. 1, in the transfer peeling apparatus 2 for transferring the image carried on the image carrier 1 to the transfer material 3 and peeling the transfer material 3 from the image carrier 1 as shown in FIG. A contact transfer member 4 that clamps the transfer material 3 in a transfer area between the image carrier 1 and electrostatically transfers an image on the image carrier 1 to the transfer material 3, and a transfer material conveyance direction of the contact transfer member 4 A neutralizer 5 disposed on the downstream side and neutralizing the transfer material 3 when passing through the transfer material, and power supply control to the neutralizer 5 is performed, and the probability that the transfer material 3 passing through the transfer area has a high water content is likely. What is necessary is just to provide it with the static elimination control means 6 by which the electric power feeding to the said static eliminator 5 is stopped on high moisture content conditions.

According to the image forming apparatus of the present invention, in the aspect including the contact transfer member and the charge eliminator, the charge removal control unit for the charge eliminator has a high water content with a high probability that the transfer material passing through the transfer region has a high water content. Since the function of stopping the power supply to the static eliminator is added under conditions, it is possible to avoid a situation where the static eliminator is operated at least when a transfer material having a high water content passes through the transfer zone. For this reason, it is possible to effectively prevent a situation where the contact transfer member and the static eliminator are conducted through the transfer material and a leakage current flows to the static eliminator, and accordingly, image defects (white spots, image scattering) due to insufficient transfer current. Can be effectively avoided.
Also, in the case of a transfer material with a high water content, peeling discharge is difficult to occur, and there is little demand for static elimination action by the static eliminator. There is no concern about it.
Furthermore, according to the transfer peeling apparatus according to the present invention, an image forming apparatus that can suppress a leakage current to the static eliminator without using the static eliminator when a transfer material having a high water content passes through the transfer region can be simplified. Can be built.

Hereinafter, the present invention will be described in detail based on embodiments shown in the accompanying drawings.
Embodiment 1
FIG. 3 shows the overall configuration of the first embodiment of the image forming apparatus to which the present invention is applied.
In the figure, the image forming apparatus includes, for example, an electrophotographic image forming engine 21 in the apparatus main body 20, and supplies a transfer material (transfer paper, OHP sheet) below the image forming engine 21 in the apparatus main body 20. The tray 22 is provided, and the upper portion of the apparatus main body 20 is configured as a discharge tray 27. The transfer material sent from the supply tray 22 is formed on one side of the apparatus main body 20 (corresponding to the left side in FIG. 3). A conveyance path 23 leading to the engine 21 and the discharge tray 27 is provided in a substantially vertical direction.

In the present embodiment, the image forming engine 21 employs, for example, an electrophotographic system, and includes a photosensitive drum 31 as an image carrier and a charging device (in this example, a charging device) that charges the photosensitive drum 31. Roll) 32, an exposure device 33 such as a laser scanning device for writing an electrostatic latent image (hereinafter referred to as a latent image) on the charged photosensitive drum 31, and a developing device for developing the latent image on the photosensitive drum 31 with toner. 34, a transfer peeling device 35 for transferring a visible image (toner image) on the photosensitive drum 31 to a transfer material and peeling the transfer material from the photosensitive drum 31, and cleaning the residual toner on the photosensitive drum 31. And a cleaning device 36.
Here, the toner used in the developing device 34 is a high tribo nonmagnetic toner having a charge amount of 10 to 40 μC / g under a high humidity environment (for example, temperature 28 ° C./humidity 85%). Those having an average particle size of 8 μm or less are used.
As the supply tray 22, for example, a plurality of (three in this example) cassette trays 41 to 43 and two large capacity trays 44 and 45 are disposed, for example. Each supply tray 22 is provided with a feeder 46 for supplying a transfer material, and each supply tray 22 and a conveyance path 23 extending in a substantially vertical direction are connected to each other via a communication path 47. .

Further, a registration roll 24 for positioning and conveying the transfer material is provided on the upstream side of the photosensitive drum 31 in the conveyance path 23, and a fixing device 25 is disposed on the downstream side of the photosensitive drum 31 in the conveyance path 23. Established.
Immediately after the fixing device 25 in the conveyance path 23, the branch path is bifurcated, one branch path 51 extends toward the discharge tray 27, and the other branch path 52 extends toward one side wall of the apparatus body 20. Between both branch paths 51 and 52, a switching gate 53 for path switching is disposed. In addition, a straight path 54 that linearly connects the two branch paths 51 and 52 is provided, and discharge rollers 55 and 56 are disposed at the exit portions of the branch paths 51 and 52. Reference numeral 57 denotes a transport roll disposed as necessary in the transport path 23 and the communication path 47.
A door cover (not shown) is provided on the side wall of the apparatus main body 20 facing the conveyance path 23 extending in the substantially vertical direction so as to be openable and closable. A double-sided recording unit 60 is provided outside the door cover. Yes. A return conveyance path 61 communicating with the branch path 52 and communicating with the upstream side of the registration roll 24 in the conveyance path 23 is provided in the double-sided recording unit 60, and a discharge path is provided in the middle of the return conveyance path 61. 62 is branched, an appropriate number of transport rolls 63 are disposed in the return transport path 61, and a discharge roll 64 is disposed at the exit portion of the discharge path 62. A second discharge tray 65 is provided at a location corresponding to the outlet of the discharge path 62 of the duplex recording unit 60.
In FIG. 3, reference numeral 70 denotes a manual feed tray for manually transferring a transfer material, and 71 denotes a manual feeder provided on the manual feed tray 70.

In the present embodiment, as shown in FIG. 4, the transfer peeling device 35 includes, for example, a transfer roll 100 in which a transfer area is secured between the transfer drum 100 and the transfer path P of the transfer material P. And the static eliminator 110 disposed on the downstream side.
Here, a transfer power supply circuit 101 is connected to the transfer roll 100, and the transfer power supply circuit 101 applies a charge having a polarity opposite to the charge of the toner image T to the transfer material P when passing through the transfer material. The transfer bias Vt is applied and constant current control is performed so that the transfer current It is constant.

For example, a static elimination needle is used as the static eliminator 110. The static elimination needle 110 is composed of a needle electrode plate having a saw-toothed end sandwiched between a pair of insulating resin plates. The static electricity supply circuit 111 as a power source for the static elimination needle is provided on the needle electrode plate of the static elimination needle 110. And a high resistance 112 of 50 to 1000 MΩ is connected in series with the static elimination power supply circuit 111.
Here, the IV characteristic of the static elimination power supply circuit 111 may be arbitrarily selected. For example, as shown in FIGS. 4 and 6, the static elimination bias Vd is controlled at a constant voltage (about 2.4 kV in FIG. 6). It is preferable to control the static elimination bias Vd at a constant voltage, and more preferably to switch to constant current control under the condition that the static elimination current exceeds a predetermined current value (4 μA in FIG. 6). At this time, switching to the constant current control may be performed by, for example, a current limiter.
According to this aspect, when the static elimination needle 110 is actuated (for example, when the second surface of the transfer material P is transferred in a dry environment), the initial voltage at the start of discharge can be ensured by constant voltage control. The static elimination action can be made uniform by keeping the static elimination current constant when the static elimination current exceeds a predetermined level.
On the other hand, when the static elimination needle 110 is not in operation (for example, when transferring the first surface of the transfer material P in a high humidity environment), the power supply by the static elimination bias Vd may be stopped.
Further, the high resistance 112 avoids a situation in which the static elimination current flows suddenly when the static elimination action is performed by the static eliminator 110. If the resistance is less than 50 MΩ, the suppression effect on the rapid flow due to the static elimination current is small. If it exceeds 1000 MΩ, there is a concern that the static elimination action may be hindered, so it is selected in the range of 50 to 1000 MΩ.

  Further, in the present embodiment, as shown in FIG. 4, a transfer material guide device 140 is disposed on the upstream side of the transfer region in the transfer path 23 (see FIG. 3) of the transfer material P. The transfer material guide device 140 includes a pair of guide chutes 141 and 142 and guides the transfer material P directly toward the transfer region or indirectly while being in close contact with the photosensitive drum 31. The guide chutes 141 and 142 are grounded via a high resistance 143 of about 50 to 300 MΩ, and both prevent frictional charging of the transfer material P and prevent the transfer current It from flowing out.

  In this embodiment, the transfer power supply circuit 101 and the charge removal power supply circuit 111 are controlled by the control device 150. As shown in FIG. 4, the control device 150 is configured by, for example, a microcomputer system, and includes a humidity sensor 151 for process control, a temperature sensor 152 for the process control, and either the single-side recording mode or the double-side recording mode as the image forming mode. The operation mode selection switch 153 for selecting whether or not the transfer material P is an OHP sheet and each information from the OHP sheet selection switch 154 for selecting whether or not the transfer material P is an OHP sheet, (Refer to FIG. 5) and the like, and the power supply circuits 101 and 111 are controlled.

Next, the operation of the image forming apparatus according to the present embodiment will be described.
As shown in FIGS. 3 and 4, when creating an image, a start switch (not shown) may be operated to start a series of image forming cycles.
In this image forming cycle, a predetermined toner image (image) T is formed on the photosensitive drum 31 by the image forming engine 21, while the transfer material P is sent out from the supply tray 22, and the registration roll 24 passes through the conveyance path 23. The toner image T on the photosensitive drum 31 is transferred to the transfer material P through the transfer material guide device 140 and transferred to the transfer material P. Thereafter, the transfer material P is transferred to the transfer tray 27 through the fixing device 25, for example. To be discharged.
Assuming that the double-sided recording mode is selected for a plurality of transfer materials P in this image forming cycle, for example, the control device 150 has a transfer power supply circuit 101 and a charge removal control circuit 111 as shown in FIG. To control.
At this time, the control device 150 controls the transfer power supply circuit 101 so that the transfer current It in the transfer area becomes constant, and controls the static elimination power supply circuit 111 according to the procedure shown in FIG.
Here, when considering the static elimination control processing, first, the control device 150 checks whether or not the environment is a high humidity environment based on information from, for example, the humidity sensor 151 and the temperature sensor 152, and then the image forming mode. After checking whether or not the transfer surface of the transfer material P is the first surface with the selection switch 153 and further checking whether or not the transfer material P is an OHP sheet with the OHP sheet selection switch 154, “high humidity environment / transfer material” The transfer surface first surface (Side1) / not an OHP sheet ”(high moisture content condition in this example) is set to OFF by sending an OFF signal to the neutralization power supply circuit 111, In other conditions, the charge eliminator (static charge needle) 110 is set to ON.
However, in this example, whether or not the environment is a high humidity environment may be appropriately selected based on the criteria. However, for example, if the temperature is 20 ° C./humidity 60% or more, it is determined that the environment is a high humidity environment.

In this embodiment, if the transfer material P satisfies the high water content condition, as shown in FIG. 7, the switch 113 of the static elimination power supply circuit 111 is cut and the static eliminator (static elimination needle) 110 is turned off. It reaches.
At this time, the transfer material P is nipped and conveyed in the transfer area between the transfer roll 100 and the photosensitive drum 31 and passes through a portion corresponding to the static eliminator 110. However, the transfer material P has a high water content condition. Even if the transfer material P is disposed across the transfer area and the portion corresponding to the static eliminator 110, the static eliminator 110 is off, so that a part of the transfer current It Therefore, the leakage current ΔIt hardly flows out to the static eliminator 110 side, and the transfer current It is surely injected into the photosensitive drum 31 in the transfer area, and the toner image T on the photosensitive drum 31 is It is reliably transferred to the transfer material P.
In the present embodiment, whether or not the water content condition is high is determined based on information from environmental sensors such as the humidity sensor 151 and the temperature sensor 152 and the transfer surface information of the transfer material P. Therefore, it is not necessary to actually measure the moisture content of the transfer material P with a moisture content sensor or the like.

  On the other hand, in order to evaluate the performance of the model of the present embodiment, when the transfer material P that satisfies the high water content condition described above passes, the transfer material P of the transfer material P is compared with respect to the comparative model that operates the static eliminator (static charge needle) 110. When the transfer peeling behavior was examined, as shown in FIG. 8, a part of the transfer current It flows out to the charge eliminator 110 side as a leakage current ΔIt via the transfer material P. It becomes insufficient, leading to a cause of transfer failure (white spots, toner scattering).

Here, when a change in the transfer current (BTR (Bias Transfer Roll) effective transfer current) of the transfer roll 100 in the comparative form model was examined, as shown in FIG. 9, the leading edge of the transfer material P entered the transfer area. In the region (corresponding to the region in FIG. 9A) that does not reach the static eliminator (in this example, the static elimination needle: DTS) 110 (corresponding to the region in FIG. 9A), the transfer current It is maintained at a predetermined level, but the tip of the transfer material P When the region corresponding to the static eliminator 110 (corresponding to the region shown in FIG. 9B) is reached, a part of the transfer current It steeply flows out toward the static eliminator 110, and the transfer current It decreases for a moment by ΔI ₁ . Further, when the transfer material P advances through the portion corresponding to the static eliminator 110, the transfer current is transferred at other portions (corresponding to the region of FIG. 9C) other than the tip portion (corresponding to the region of FIGS. 9A and 9B) of the transfer material P. Since a part of It continues to flow out to the static eliminator 110 side, the transfer current It remains lowered to a level lower by ΔI ₂ than the normal level in the A region. Accordingly, it is understood that the transferability is lowered in the B and C regions of the transfer material P as the transfer current It is reduced.

By the way, in this embodiment, when the transfer material P is an OHP sheet, even if the transfer surface of the transfer material P is the first surface in a high humidity environment, the OHP sheet has a high water content. It is not treated, and it is treated as not satisfying the high water content condition.
Therefore, in the case of an OHP sheet, even if the transfer surface of the transfer material P is the first surface in a high-humidity environment, the static eliminator 110 operates, and the OHP sheet is neutralized by the static eliminator 110. It is peeled from the body drum 31. At this time, since the OHP sheet does not have a high water content, there is no concern that a part of the transfer current It flows out as a leakage current ΔIt to the static eliminator 110 side through the OHP sheet.

Further, in a mode in which a heater (tray heater) (not shown) is incorporated in all or part of the supply tray 22 (41 to 45) as shown in FIG. 3, the tray heater is shown in FIG. By turning on / off the switch 155, the tray heater can be selectively turned on / off.
In such an aspect, the on / off setting of the tray heater switch 155 is set to be on in a high humidity environment in conjunction with the humidity sensor 151 that is an environmental sensor, for example, or in the high humidity environment, for example, SE. It is possible to select as appropriate, such as setting to ON.
In such an embodiment, when the tray heater is on, the transfer material P accommodated in the supply tray 22 is heated by the tray heater, so that it may reach a high water content state. Absent.
Therefore, in this aspect, as shown by the phantom line in FIG. 5, it is determined whether or not the tray heater is on. If the tray heater is on, the transfer surface of the transfer material is assumed to be under a high humidity environment. Even if it is the first surface, the static eliminator 110 may be turned on as in the normal operation example.

Furthermore, in the present embodiment, the transfer sequence of the transfer material P in the double-sided recording mode may be arbitrarily selected. For example, when the transfer material P is a small size paper, the normal environmental conditions and the high humidity environment A method of changing the conveyance sequence depending on the condition is adopted.
For example, as shown in FIGS. 10A and 10B, when the transfer material P is a large size paper (for example, A3), an image forming process for the transfer material P (for example, P (1) to P (3)) is performed. Are performed alternately one by one on the first surface (Side1) and the second surface (Side2).
At this time, in the normal operation example (normal environment), the static eliminator (static charge needle: DTS) 110 is turned on (C / In: cycle in) after the main motor on timing t _{0 as} shown in FIG. ) Is started, the ON operation is continued during the image forming process of the first surface (Side 1) and the second surface (Side 2) of the transfer material P, and the timing t ₅ after the cycle-out process (for example, transfer to the transfer roll 100) The operation is turned off after a predetermined time elapses after the bias Vt is turned off.
On the other hand, in a high humidity environment, the static eliminator 110 is turned off during the image forming process of the first surface (Side1) of the transfer material P as shown in FIG. Switching is controlled so that the side 2) is turned on during the image formation process.
In FIG. 10B, t ₁ is the start of applying the transfer bias Vt to the transfer roll 100 (for example, before the registration clutch 24 is turned on), and t ₂ and t ₃ are the start of applying the transfer bias Vt to the transfer roll 100. simultaneous (registration clutch oN after a predetermined time has elapsed), the start timing t ₄ of the cycle-out process is the final transfer material P (3) is passed through at a predetermined time interval has elapsed the registration sensor resist roller 24, transfer roller in this timing The bias applied to 100 is switched to, for example, a cleaning bias having a polarity opposite to that of the transfer bias Vt.
In addition, in FIG. 10B, the transfer behavior of the transfer material P at reference numerals (I) and (II) is shown in FIG.

In addition, as shown in FIGS. 11A and 11B, when the transfer material P is a small size paper (for example, A4LEF: Long Edge Feed), the transfer material P (P (1) ˜ Image formation processing for P (3)) is performed alternately one by one on the first surface (Side1) and the second surface (Side2) (see FIG. 11A). At this time, the static eliminator 110 is in an ON operation state on both the first surface and the second surface of each transfer material P.
On the other hand, in a high humidity environment, as shown in FIG. 11B, the first surface (Side 1) of the first and second transfer materials P (P (1), P (2)) The image forming process continues, and then the second surface (Side2) of the first transfer material P (1), the first surface of the third transfer material P (3), and the second sheet. An image forming process is performed on the second surface (Side2) of the third transfer material P (2), P (3).
At this time, in a high-humidity environment, the static eliminator 110 is in an off operation state with respect to the first surface (Side1) of the transfer material P and is turned on with respect to the second surface (Side2) of the transfer material P. Are switched as follows.
Here, timings t _{0 to} t ₅ in FIGS. 11 (a) and 11 (b) correspond to the timings in FIGS. 10 (a) and 10 (b). In FIG. The transfer behavior of the transfer material P in (II) and (III) is shown in FIGS. 13 and 14, respectively.

Further, in this embodiment, the configuration of the transfer roll 100 is arbitrary, but as the transfer roll 100 in a particularly preferable aspect, at least a semiconductive elastic layer is formed on the outer periphery of a conductive support (roll base). A semiconductive member is used. The semiconductive member is a conductive and semiconductive member used as various devices of an image forming apparatus, such as a charging member, a transfer member, a primary transfer member and a secondary transfer member in an intermediate transfer system, a cleaning member, and a charge eliminating member. It is a conductive member (hereinafter referred to as a semiconductive member), and the shape thereof is not limited to a roll shape but may be a blade shape.
Next, the semiconductive member used in the present embodiment has the following components (A) to (C) as essential components, and the total amount of the components (A) and (B) is 100 parts by mass. The component (C) is formed of a rubber composition containing 10 to 80 parts by mass.
(A) Epichlorohydrin-allyl glycidyl ether copolymer (B) Acrylonitrile-butadiene rubber (NBR)
(C) Electroconductive agent

Thus, it is essential that the semiconductive member used in the present embodiment has a semiconductive elastic body layer containing the components (A) to (C).
As in the present embodiment, a semi-conductive rubber composition comprising a combination of epichlorohydrin-allyl glycidyl ether copolymer (component A) having high ion conductivity and NBR (component B) having low ion conductivity. By forming the elastic layer, the conductivity of the semiconductive elastic layer is governed by ionic conduction, and the voltage dependency of the electrical resistance is reduced. And by blending a predetermined amount of an electron conductive conductive agent (component C) into this rubber composition, the electrical resistance under low temperature and low humidity becomes low and close to the electrical resistance under high temperature and high humidity. As a result, the electrical resistance value does not fluctuate greatly even under high temperature and high humidity or low temperature and low humidity, and it is difficult to be influenced by the environment such as temperature and humidity, that is, the environmental dependency is reduced. Further, since no low molecular ion conductive agent is added, there is no problem of blooming, and as a result, contamination of the surface of the semiconductive member and the surface of the photoreceptor can be prevented.

The rubber components used in the present embodiment are epichlorohydrin-allyl glycidyl ether copolymer (component A) and NBR (component B). The epichlorohydrin-allyl glycidyl ether copolymer (component A) and NBR (component B) are highly compatible and are uniformly dispersed when blended. As a result, the rubber material has a small resistance variation. The compounding ratio of the epichlorohydrin-allyl glycidyl ether copolymer (component A) and NBR (component B) can be set in the range of (A) / (B) = 80/20 to 20/80 in terms of mass ratio. preferable. More preferably, (A) / (B) = 60/40 to 40/60.
That is, when the epichlorohydrin-allylglycidyl ether copolymer (component A) is less than 20 (NBR (component B exceeds 80)) in the blending ratio (blending ratio), the obtained semiconductive member In the case where the initial electrical resistance tends to increase, and the epichlorohydrin-allyl glycidyl ether copolymer (component A) exceeds 80 [NBR (component B) is less than 20), the ion conductivity becomes strong, The environmental dependency of electrical resistance tends to be high. Therefore, it is necessary to increase the addition amount of the electron conductive conductive agent, which may cause problems such as an increase in roll hardness.

Moreover, when the epichlorohydrin-allyl glycidyl ether copolymer (A component) and NBR (B component) are used together as a rubber composition which forms the said semiconductive elastic body layer like this Embodiment, NBR ( Since the component B) can be made into a low-viscosity polymer, the extrusion pressure can be reduced and the effect of improving the extrusion skin can be obtained in extrusion molding and the like.
As the forming material of the semiconductive elastic layer, as described above, epichlorohydrin-allyl glycidyl ether copolymer (component A), NBR (component B), and electron conductive conductive agent (component C) are used. With respect to 100 parts by mass (hereinafter, abbreviated as “part” as appropriate) of the above-mentioned components (A) and (B) that are essential components and rubber components, A rubber composition set in the range of 80 parts is used. More preferably, the component (C) is in the range of 30 to 70 parts. When the component (C) is within this range, it is possible to effectively reduce the fluctuation range of the electric resistance due to the environmental change and voltage change of the obtained semiconductive member.
That is, when the blending amount of the electron conductive conductive agent (C component) is less than 10 parts, there is a tendency that the effect of electron conduction that affects the fluctuation range is not observed. There may be a problem that the hardness of the conductive roller becomes hard and the nip pressure at the transfer portion increases.

Examples of the electron conductive conductive agent (component C) include metals such as carbon black, graphite, aluminum, nickel, and copper alloys, or alloys, tin oxide, zinc oxide, kalim titanate, tin oxide-indium oxide, and tin oxide. -Metal oxides, such as antimony oxide complex oxide, etc. are mentioned, Among these, carbon black is preferable.
Carbon black suitable as an electron conductive conductive agent (component C) has a property of binding in a chain form in the rubber composition to which this is added, and the resistance value of the rubber composition depends on the length of the chain bond. Will be different. If this chain bond is long, the conductivity of the semiconductive elastic layer is improved and its resistance value is lowered. On the other hand, if the chain bond is short, the conductivity of the semiconductive elastic layer is lowered and its resistance value is increased. That is, when carbon black that forms a long chain bond is added, the amount of carbon black added to develop a desired resistance value can be reduced compared to carbon black that forms a short chain bond. Since the resistance value changes greatly, it is impossible to reduce the variation in the resistance value in the semiconductive elastic layer described above.

In addition, as the electron conductive conductive agent (C component) in the present embodiment, it is also preferable to use two types of carbon blacks having different characteristics such as surface characteristics.
The length of the above-mentioned chain bond depends on the particle size and surface activity of the individual particles of carbon black. As one index indicating this, DBP (dibutyl phthalate) defined in ASTM D2414-6TT is used. ) Oil-absorbing. This DBP oil absorbency is expressed by whether the DBP amount (ml) absorbed by 100 g of carbon black is large or small. Carbon blacks with higher DBP oil absorption, that is, more oil absorption are considered to form longer chain bonds.
If only the carbon black having a high DBP oil-absorbing property is added to the rubber composition to adjust the resistance value of the elastic layer, the resistance value greatly changes even if the addition amount is slightly increased or decreased. Therefore, a predetermined resistance value cannot be imparted to the elastic layer unless the addition amount and dispersion state of carbon black are strictly defined. On the other hand, if only the carbon black having a low DBP oil absorbency is added and the resistance value of the elastic layer is adjusted, the carbon black is substantially less in the rubber composition than the case where only the carbon black having a high DBP oil absorbency is added. Since it disperses uniformly, the rate of change in resistance value with an increase or decrease in the amount added decreases. However, in order to impart a predetermined resistance value to the elastic layer, it is necessary to add a larger amount of carbon black than when adding only carbon black having high DBP oil absorption. As a result, since the blending ratio of carbon black in the rubber composition is increased, the rubber composition becomes highly viscous when kneaded with a Banbury mixer, a kneader or the like, so that processing becomes difficult. Moreover, the problem that the obtained elastic layer becomes high hardness may generate | occur | produce.
Therefore, it is preferable to use two or more types of carbon blacks having different DBP oil absorption properties of carbon black having a high DBP oil absorption property and carbon black having a low oil absorption property.

The carbon black added to the material for forming the semiconductive elastic layer may be any carbon black having a difference in DBP oil absorption, but if this difference is too small, it is the same as the case where one kind of carbon black is added. Will produce negative results. Accordingly, carbon black having a certain degree of difference in DBP oil absorption is preferable. Carbon oil with high DBP oil absorption has an oil absorption of 250 ml / 100 g or more, and carbon black with low oil absorption has an oil absorption of 100 ml / 100 g. It is preferable to combine the following.
Specifically, as carbon black having high oil absorption, for example, HS-500 (made by Asahi Carbon Co., Ltd.) with an oil absorption amount of 447 ml / 100 g, Ketjen Black (made by Lion Azo Co., Ltd.) with an oil absorption amount of 360 ml / 100 g And carbon black such as Vulcan XC-72 (manufactured by Cabot Corporation) having an oil absorption of 288 ml / 100 g and Vulcan XC-72 having an oil absorption of 265 ml / 100 g. Moreover, as carbon black with low oil absorption, Asahi Thermal FT (Asahi Carbon Co., Ltd.) having an oil absorption of 28 ml / 100 g, Asahi Thermal MT (Asahi Carbon Co., Ltd.) having an oil absorption of 35 ml / 100 g, etc. Thermal black etc. are mentioned.

In addition to the components (A) to (C), a cross-linking agent, a filler, a foaming agent, and the like are appropriately blended in the semiconductive elastic body layer as necessary. However, the component constituting the semiconductive elastic body layer in the present invention does not include an ion conductive conductive agent.
The crosslinking agent is not particularly limited, and conventionally known ones such as thiourea, triazine, sulfur and the like can be mentioned. Examples of the filler include insulating fillers such as silica, talc, clay and titanium oxide, and these may be used alone or in combination. Moreover, as said foaming agent, any of an inorganic type foaming agent and an organic type foaming agent may be used, for example, These may be used independently and may be used together 2 or more types.
In the present embodiment, the semiconductive elastic layer in the semiconductive member is produced by using a mixer such as a tumbler, a V-type blender, a nauter mixer, a Banbury mixer, a kneading roller, or an extruder. Can do. Moreover, when manufacturing the semiconductive elastic body layer in the present embodiment, the mixing method of each component and the order of mixing are not particularly limited. As a general method, all components are mixed in advance with a tumbler, V blender, etc., and uniformly melt-mixed by an extruder. Depending on the shape of the components, two or more types of molten mixtures in these components are used. Alternatively, a method of melt-mixing the remaining components can be used.

Hereinafter, the semiconductive member according to the present embodiment will be described in more detail.
The conductive support in the semiconductive member of the present embodiment is made of a metal such as SUS or SUM, for example. In the case of a semiconductive member having a roll-like structure, the conductive support is disposed so as to penetrate the axial direction of the semiconductive member, and can also function as a rotating shaft of the semiconductive member. Further, since an external power supply is connected to the conductive support and a desired bias is applied, it also functions as a voltage application means to the semiconductive member together with the external power supply.
The semiconductive elastic body layer is formed on a conductive support, and as described above, is composed of a specific rubber composition containing the components (A) to (C), and has a hardness according to the use of the semiconductive member. The surface characteristics (surface roughness, friction coefficient), electrical characteristics (electric resistance), etc. are adjusted. By appropriately adjusting various conditions such as electrical characteristics and surface characteristics of the semiconductive elastic layer, it can be suitably used not only for transfer rolls but also for various other members (charging members, charge removal members, etc.). .
Further, specifically, as the surface characteristics, the roll hardness is preferably adjusted to a range of 10 ° to 70 ° with an Asuka C hardness described in JISK-7312. For example, when used as a transfer roll More preferably, it is in the range of 10 ° to 50 °. When used as a charging member, it is more preferably in the range of 20 ° to 70 °.
Specifically, as the electrical characteristics, the volume resistance value of the semiconductive elastic layer is preferably adjusted to a range of 10 ³ to 10 ¹⁰ Ω, and more preferably 10 ⁶ to 10 when used as a transfer roll. The range is ¹⁰ Ω. When used as a charging member, it is more preferably in the range of 10 ⁵ to 10 ⁸ Ω.

The volume resistance value (R) of the semiconductive elastic layer is determined by applying a load of 500 g to both ends of the semiconductive member on the roll-like semiconductive member on a metal plate or the like. This is obtained by applying a voltage of 1.0 kV (V) to the sex member, reading the current value I (A) after 10 seconds, and calculating by the following equation.
R = V / I
The thickness of the semiconductive elastic layer is generally set to about 2 to 12 mm, and a suitable range is 3 to 5 mm.
Furthermore, the configuration of the semiconductive elastic body layer is not limited as long as the surface characteristics, electrical characteristics, and the like are adjusted according to the application, and the semiconductive elastic body layer may be composed of a single layer or a plurality of layers. Good.

Embodiment 2
FIG. 15 shows a main part of the second embodiment of the image forming apparatus to which the present invention is applied.
In the figure, the basic configuration of the image forming apparatus is provided with a transfer peeling device 35 and its control system similar to those in the first embodiment, but the discrimination method for the high water content condition is different from that in the first embodiment. Yes. Components similar to those in the first embodiment are denoted by the same reference numerals as those in the first embodiment, and detailed description thereof is omitted here.
In the present embodiment, the transfer roll 100 is composed of a semiconductive member having ion conductivity, as in the first embodiment. Since the transfer roll 100 is highly environment dependent, the resistance of the transfer roll 100 varies greatly depending on, for example, whether the environment is a high humidity environment.
In this example, the environmental dependency of the transfer roll 100 is used, and the environmental change information to the control device 150 is, for example, a transfer roll instead of the detection information from the humidity sensor 151 and the temperature sensor 152 (see FIG. 4). In 100 resistance measurement cycles, the current value of the transfer power supply circuit 101 is monitored, and the resistance value of the transfer roll 100 is determined based on this monitor value. As for the resistance indexing method of the transfer roll 100, a determination table for obtaining the relationship between the monitor current and the resistance of the transfer roll 100 is prepared in the memory of the control device 150 in advance, and this determination table is searched. It is possible to select as appropriate.
Therefore, even in the present embodiment, the control device 150 monitors the resistance change of the transfer roll 100, determines whether or not the moisture content condition is high, and performs a static elimination control process as shown in FIG. Is adopted. The OHP sheet and tray heater are preferably processed in the same manner as in the first embodiment.

Embodiment 3
FIG. 16 shows a main part of a third embodiment of the image forming apparatus to which the present invention is applied.
In the figure, the basic configuration of the image forming apparatus includes a transfer peeling device 35 and its control system similar to those of the first embodiment, but the configuration of the fixing device 25 is different from that of the first embodiment. Yes. Components similar to those in the first embodiment are denoted by the same reference numerals as those in the first embodiment, and detailed description thereof is omitted here.
In the present embodiment, the fixing device 25 includes a heat-fixing roll 161 and a pressure-fixing roll 162 disposed in pressure contact with the heat-fixing roll 161. The heat-fixing roll 161 has a heater 163 built in the roll body. On the other hand, the pressure-fixing roll 162 includes a high-resistance layer 164 on the surface of the roll body, and a fixing power supply circuit 165 is provided on the high-resistance layer 164. Connected. The fixing power supply circuit 165 applies a fixing bias Vf (for example, 200 to 1000 V) having the same polarity as the transfer bias Vt.
In the present embodiment, the distance between the transfer area between the photosensitive drum 31 and the transfer roll 100 and the fixing area between the fixing rolls 161 and 162 is arranged across the transfer material P to be used. It is selected to the extent.

Therefore, according to the present embodiment, the fixing device 25 basically has the following operation.
That is, the transfer material P that has passed through the transfer area passes through the fixing area between the fixing rollers 161 and 162. At this time, if it is assumed that the transfer material P satisfies the high water content condition, the transfer material P is heated by the fixing rolls 161 and 162 in the fixing region. The transfer material P that has not reached the fixing area is heated. Then, as shown in the area M of FIG. 17, a phenomenon occurs in which the moisture 170 in the transfer material P evaporates, and a part of the unfixed toner image T on the transfer material P is indicated by T ′ due to the wind pressure due to the water vapor explosion. There is a concern that the phenomenon of scattering will occur. In particular, in a toner image T composed of a continuous solid image such as a linear image, the wind pressure due to the water vapor explosion is completely blocked by the toner image T. Is easy to scatter.
However, in this embodiment, since the fixing power supply circuit 165 applies the fixing bias Vf having the same polarity as the transfer bias Vt to the pressure fixing roll 162, as shown in the N region of FIG. Since the fixing electric field E acts on the toner image T, the scattering of the toner image T is effectively suppressed, and the toner image T is fixed as a fixing toner image Tf in the fixing area.

  Further, in the present embodiment, when the transfer material P satisfies the high water content condition, as shown in FIG. 18, the static eliminator (static charge needle: DTS) 110 is set to be off. For this reason, even if the transfer material P that satisfies the high water content condition is disposed between the transfer region and the fixing region, a part of the fixing current accompanying the fixing bias Vf is passed through the transfer material P as a leakage current ΔIf. It does not flow out toward the static eliminator 110 side. Therefore, the electric charge e held on the back surface of the transfer material P positioned immediately after passing through the transfer area does not become excessive, and a leakage current flows out to the static eliminator 110 or the toner is charged to a reverse polarity, and the photosensitive drum There is no concern of shifting to the 31 side. Therefore, the transfer material P that has passed through the transfer area is guided to the fixing device 25 side while the toner image T is securely held.

On the other hand, for example, even if the transfer material P satisfies the high water content condition, the transfer material P satisfying the high water content condition as shown in FIG. Is disposed between the transfer region and the fixing region, there is a concern that a part of the fixing current accompanying the fixing bias Vf flows out toward the static eliminator 110 via the transfer material P as a leakage current ΔIf. . At this time, due to insufficient fixing electric field, the toner scattering phenomenon that occurs immediately before the fixing area cannot be effectively suppressed, and fixing failure may occur.
Further, when a part of the fixing current leaks out to the charge eliminator 110 side, the charge e becomes excessive on the back surface of the transfer material P located immediately after passing through the transfer region, and leaks to the charge eliminator 110. There is a concern that current flows out or that the toner is charged to a reverse polarity and transferred to the photosensitive drum 31 side. In particular, when a part of the fixing current flows out to the static eliminator 110 side, the transfer current leakage phenomenon is also increased and the amount of leakage current of the transfer current is further increased. It tends to lead to transfer failure.

In this example, the image forming apparatus model according to the first embodiment (DTS is used as a static eliminator) is used. High humidity environment / Side1 only DTS Off / P paper-A3 fresh (immediately after opening the encapsulated transfer paper) The transfer current was sequentially changed for each of the experimental conditions 1) in high humidity environment / Side 1 only, and DTS Off / 4024 paper 11 "× 17" 9.6% (seasoning paper). The transfer defects (transferability Side1, white-out Side1, ghost Side1) were evaluated visually.
Further, in evaluating the performance of the present embodiment, a model configuration substantially similar to that of the embodiment and a mode in which the static eliminator is turned on regardless of the transfer surface of the transfer material in all environments is used as a comparative example. The transfer current was sequentially changed for all-environment DTS On / P paper-A3 fresh experiment condition 3 and high-humidity environment / all-environment DTS On / 4024 paper 11 "x 17" 9.6% (seasoning paper) experiment condition 4. The transfer defects in each case (transferability Side1, white-out Side1, ghost Side1) were visually evaluated.
In Examples and Comparative Examples, the charging characteristics of the toner used are, for example, 25 μC / g under a high humidity environment, and the high humidity environment means a temperature of 28 ° C./85% humidity.

Here, the results of the experimental conditions 1 to 4 are shown in FIGS. The target grade of the transfer defect (image defect) was G2 (corresponding to a level at which most of the transfer defects cannot be visually confirmed).
First, considering this embodiment, in the case of the experimental conditions 1 and 2, as shown in FIGS. 20 and 21, for example, It (a) is selected as a good transfer current within the allowable level range W of each transfer defect. Is possible. In this case, the common good current region W in both experimental conditions 1 and 2 can be secured to some extent. For this reason, it is possible to prevent the deviation of the good transfer current between the water-containing paper (low resistance paper (experimental condition 2)) and the non-water-containing paper (high resistance paper (experimental condition 1)), and the transfer latitude is widened accordingly. In addition to being able to set, a good transfer image can be reliably obtained even with water-containing paper.

On the other hand, when the comparative example is examined, in the case of the experimental condition 3, as shown in FIG. 22, it is possible to select It (a) as a good transfer current within the allowable level range of each transfer defect, for example. It is. However, in the case of the experimental condition 4, as shown in FIG. 23, it is not possible to select a good transfer current within the allowable level range of each transfer defect. Even if one of the allowable levels is set lower, it ( It (b), which deviates significantly from a), must be selected.
That is, in the comparative example, it is not possible to prevent the deviation of the good transfer current between the water-containing paper (low resistance paper (experimental condition 4)) and the non-water-containing paper (high resistance paper (experimental condition 3)), and the transfer latitude is wide. It is difficult to ensure, and it is understood that it is difficult to maintain good transfer performance in the case of water-containing paper.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory view showing an outline of an image forming apparatus according to the present invention and a transfer peeling apparatus used for the image forming apparatus. (A) is explanatory drawing which shows the effect | action of the transfer peeling apparatus which concerns on this invention model, (b) is explanatory drawing which shows the effect | action of the transfer peeling apparatus which concerns on a comparison model. 1 is an explanatory diagram showing an overall configuration of Embodiment 1 of an image forming apparatus to which the present invention is applied. It is explanatory drawing which shows the transfer peeling apparatus which concerns on Embodiment 1, and its control system. 3 is a flowchart illustrating a static elimination control process used in the first embodiment. 6 is an explanatory diagram illustrating an example of IV characteristics of a power supply for a static elimination needle used in Embodiment 1. FIG. FIG. 6 is an explanatory diagram illustrating an operation example of the transfer peeling apparatus according to the first embodiment. It is explanatory drawing which shows the operation example of the transfer peeling apparatus which concerns on the form model of a comparison. It is explanatory drawing which shows the malfunction of the transfer peeling apparatus which concerns on the form model of a comparison. (A) is explanatory drawing which shows the example of a normal operation | movement in the case of a large size paper at the time of double-sided recording mode, (b) is explanatory drawing which shows the example of an operation | movement at the time of a high humidity environment in the same case. (A) is explanatory drawing which shows the normal operation example in the case of the small size paper at the time of double-sided recording mode, (b) is explanatory drawing which shows the operation example at the time of a high humidity environment in the same case. (I), (II) is explanatory drawing which shows typically the operation state of the corresponding | compatible part of FIG.10 (b). (I), (II) is explanatory drawing which shows typically the operation state of the corresponding | compatible part of FIG.11 (b). (III) is explanatory drawing which shows typically the operation state of the corresponding | compatible part of FIG.11 (b). It is explanatory drawing which shows the transfer peeling apparatus which concerns on Embodiment 2, and its control system. FIG. 5 is an explanatory diagram showing a transfer peeling device, a control system thereof, and a fixing device according to a third embodiment. FIG. 10 is an explanatory diagram illustrating an operation of a fixing device used in a third embodiment. 10 is an explanatory diagram illustrating an operation example of a transfer peeling apparatus according to Embodiment 3. FIG. It is explanatory drawing which shows the operation example of the transfer peeling apparatus which concerns on the form of a comparison. In the transfer peeling apparatus which concerns on an Example, it is explanatory drawing which shows the relationship between the transfer electric current at the time of using a fresh paper by DTS Off only in high humidity environment / Side1. In the transfer peeling apparatus which concerns on an Example, it is explanatory drawing which shows the relationship between the transfer current at the time of using seasoning paper (water-containing paper) by DTS Off only in high humidity environment / Side1. In the transfer peeling apparatus which concerns on a comparative example, it is explanatory drawing which shows the relationship between the transfer electric current at the time of using fresh paper by high humidity environment / all environment DTS On, and a transfer defect. In the transfer peeling apparatus which concerns on a comparative example, it is explanatory drawing which shows the relationship between the transfer electric current at the time of using seasoning paper (water-containing paper) by high-humidity environment / all environment DTS On. It is explanatory drawing which shows the relationship between the transfer current and the transfer defect in the use conditions of high humidity environment / low charge toner / seasoning paper (water-containing paper) with respect to the conventional model of the transfer peeling apparatus. It is explanatory drawing which shows the relationship between the transfer current and the transfer defect in the use conditions of high humidity environment / highly charged toner / seasoning paper (water-containing paper) with respect to the conventional model of the transfer peeling apparatus.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Image carrier, 2 ... Transfer peeling apparatus, 3 ... Transfer material, 4 ... Contact transfer member, 5 ... Static eliminator, 5a ... Static elimination member, 6 ... Static elimination control means, 7 ... Transfer control means, 8 ... Environment discrimination means , 9: Transfer surface discriminating means, 10: Fixing means, 11: Fixing member, Vd ... Static elimination bias, Vt ... Transfer bias

Claims (14)

In an image forming apparatus comprising: an image carrier that carries an image; and a transfer peeling device that transfers an image on the image carrier to a transfer material and peels the transfer material from the image carrier.
The transfer peeling device includes a contact transfer member that sandwiches a transfer material in a transfer region between the image carrier and electrostatically transfers an image on the image carrier to the transfer material;
A static eliminator disposed on the downstream side of the contact transfer member in the transfer material conveyance direction and neutralizing the transfer material when passing through the transfer material;
Power removal control is performed for the static eliminator, and the static eliminator control means for stopping the power supply to the static eliminator under a high water content condition with a high probability that the transfer material passing through the transfer region has a high water content,
An image forming apparatus comprising: The image forming apparatus according to claim 1.
An image forming apparatus characterized in that the high water content condition of the static elimination control means is at the time of transferring the first surface of the transfer material in a high humidity environment. The image forming apparatus according to claim 2.
The static elimination control unit includes an environment determination unit that determines whether the humidity environment is high, and a transfer surface determination unit that determines whether the transfer surface of the transfer material is the first surface or the second surface. An image forming apparatus. The image forming apparatus according to claim 3.
An image forming apparatus, wherein the environment determining means determines whether or not the environment is a high humidity environment based on information from an environment sensor for process control. The image forming apparatus according to claim 3.
An image forming apparatus characterized in that the environment discriminating means discriminates whether or not the environment is a high humidity environment based on the environmental dependence of the contact transfer member made of an ion conductive material. The image forming apparatus according to claim 1.
An image forming apparatus, wherein the static eliminator includes a static elimination member to which a static elimination bias is applied, and the static elimination control means controls the static elimination bias at a constant voltage. The image forming apparatus according to claim 6.
An image forming apparatus, wherein the charge removal control unit performs constant voltage control of a charge removal bias and switches to constant current control under a condition that exceeds a predetermined current value. The image forming apparatus according to claim 1.
An image forming apparatus characterized in that the static eliminator has a high resistance of 50 to 1000 MΩ connected in series to its power supply path. The image forming apparatus according to claim 1.
An image forming apparatus, wherein the contact transfer member is constant current controlled by a transfer control means. The image forming apparatus according to claim 2.
The image forming apparatus characterized in that the charge removal control means operates the charge remover under the condition that the transfer material is an OHP sheet, even during the transfer of the first surface of the transfer material in a high humidity environment. The image forming apparatus according to claim 2, wherein a heater is provided in the transfer material supply tray.
The neutralization control means operates the static eliminator under the condition that the transfer material supply tray heater is operating, even when the first surface of the transfer material is being transferred in a high humidity environment. Forming equipment. The image forming apparatus according to claim 1.
An image forming apparatus, wherein the image is formed of a high tribo image material. The image forming apparatus according to claim 1.
A fixing device is provided on the downstream side in the transfer material conveyance direction of the static eliminator, and this fixing device is provided with a fixing member that is in contact with the transfer material and to which a bias having a polarity opposite to the charging polarity of the image material is applied. An image forming apparatus. In a transfer peeling apparatus for transferring an image carried on an image carrier to a transfer material and peeling the transfer material from the image carrier,
A contact transfer member for electrostatically transferring an image on the image carrier to the transfer material by sandwiching the transfer material in a transfer area between the image carrier and the image carrier;
A static eliminator disposed on the downstream side of the contact transfer member in the transfer material conveyance direction and neutralizing the transfer material when passing through the transfer material;
Power removal control is performed for the static eliminator, and the static eliminator control means for stopping the power supply to the static eliminator under a high water content condition with a high probability that the transfer material passing through the transfer region has a high water content,
A transfer peeling apparatus comprising:

Images