JP2000214689A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain the occurrence of an abnormal image and to restrain the complication of structure by providing an electrically grounded erase member for performing the non-contact erase of the backside of transfer material passing between guides and setting the volume resistivity of the surface part of the guide with which the transfer material comes in contact to a specified value or more. SOLUTION: The 1st guide 40 is arranged at a position on a downstream side from a transfer belt 22 and the 2nd guide 41 is arranged at a position on more downstream side than the 1st guide 40, and the erase member 42 is arranged in space between the 1st and the 2nd guides 40 and 41. The 1st and the 2nd guides 40 and 41 are respectively fixed and supported by supporting members 43 and 44, and the member 42 is also fixed and supported by the member 44. The volume resistivity of the surface part of the 1st guide 40 with which the transfer material P separated from the belt 22 comes in contact is set to be equal to or above a middle resistance, that is, >=106 Ωcm. When the transfer material P passes between the 1st and the 2nd guides 40 and 41, erase action by discharge acts on the material P by the member 42.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transfer belt for carrying and transferring a transfer material so that the transfer material passes through a transfer portion and is formed of a material having a medium volume resistivity at least at a surface portion in contact with the transfer material. Having, by the action of the voltage applied to the transfer belt, the toner image formed on the surface of the image carrier, in the transfer unit, transferred to the surface of the transfer material,
The present invention relates to an image forming apparatus that fixes a toner image transferred to a transfer material by a fixing device.

[0002]

2. Description of the Related Art In an image forming apparatus of the above type configured as an electronic copying machine, various printers, facsimile machines, or a multifunction machine having at least two of these functions, a transfer material leaves a transfer belt, It is sent to the fixing device. On the surface of the transfer material leaving the charge removing member and heading toward the fixing device, a toner image adhered mainly by an electric coupling force is carried. At that time, since the transfer material leaves the transfer belt in a charged state, if the transfer material is not removed, the toner image on the transfer material is disturbed in the transport path to the fixing device,
An abnormal image such as image dust may occur.

From this viewpoint, a grounded conductive guide plate is provided downstream of the transfer belt in the transfer material transport direction, and the transfer material separated from the transfer belt is guided by the guide plate, and the transfer material is neutralized. (For example, Japanese Patent Laid-Open No. 7-271200).
However, according to this configuration, the charge is removed by contacting the transfer material with the guide plate, so when the transfer material lands on the guide plate, the charge is rapidly removed, thereby disturbing the toner image on the transfer material, An abnormal image may occur. Particularly, in a high-temperature and high-humidity environment, when a transfer material carrying an unfixed toner image on the back surface passes over the guide plate during duplex printing in which a toner image is formed on the back surface of the transfer material, the toner image is disturbed. Cheap. This is because, in a high-temperature and high-humidity environment, the electrical resistance of the guide plate surface decreases, but once the transfer material passes through the fixing device, the resistance of the transfer material increases, and the transfer material is easily charged. Because it is.

Further, if the transfer material is contacted with a charge removing member such as a guide plate to remove the charge, an abnormal image due to uneven contact between the charge removing member and the transfer material and frictional resistance due to the contact between the transfer material and the transfer material tend to occur. Become.

In order to avoid the above-mentioned problem, it is desirable that the transfer material separated from the transfer belt be gently discharged by a grounded discharging member which does not contact the transfer material. However, there are various types of transfer materials, from thick to small, and their stiffness is not constant.
The state of the transfer material leaving the transfer belt greatly varies. For this reason, it is difficult to keep the distance between the charge removing member and the transfer material constant, and it is difficult to uniformly remove the charge from the transfer material as a whole, which may disturb the toner image on the transfer material. . In order to eliminate such a problem, a high voltage having a polarity opposite to that of the transfer bias may be applied to the charge removing member. With this configuration, even if the distance between the charge removing member and the transfer material slightly varies, it is possible to uniformly remove the charge from the transfer material. However, applying a voltage to the charge removing member requires a high-voltage power supply and a leak prevention unit, which complicates the configuration of the image forming apparatus and inevitably increases the cost.

[0006]

SUMMARY OF THE INVENTION The present invention has been made on the basis of the above-described novel recognition, and an object of the present invention is to provide a transfer material which has been separated from a transfer belt in a constantly stable state. Another object of the present invention is to provide an image forming apparatus of the type described at the beginning, which can uniformly and gently neutralize electricity to suppress occurrence of an abnormal image, and suppress increase in cost and complexity of the structure.

[0007]

According to the present invention, in order to achieve the above object, in an image forming apparatus of the type described at the beginning, a first guide for supporting a transfer material after passing the transfer belt, a transfer material A second guide disposed downstream of the first guide and supporting the transfer material after passing through the first guide, between the transfer belt and the fixing device. An electrically grounded static elimination member for performing non-contact static elimination is provided from the back surface of the transfer material passing between the first guide and the second guide, and a surface portion of the first guide to which the transfer material contacts is provided. An image forming apparatus is proposed, wherein the volume resistivity is set to 10 ⁶ Ωcm or more (claim 1).

At this time, it is advantageous to provide a connecting portion for connecting the first guide and the second guide while leaving a charge eliminating space between the first guide and the second guide. Claim 2).

Further, in the image forming apparatus according to the second aspect, when one transfer material is supported by the first guide and the second guide, the transfer material does not contact the connection portion. It is advantageous to form the connecting part in the second embodiment (claim 3).

Further, in the image forming apparatus according to the second or third aspect, it is advantageous that the connecting portion extends obliquely with respect to the transfer material conveying direction (claim 4).

Further, in the image forming apparatus according to the first aspect, it is advantageous that a downstream portion of the first guide in the transfer material transport direction is bent downward (claim 5).

6. The image forming apparatus according to claim 1, wherein the first guide has a guide base material and a sheet material fixed on an upper surface of the guide base material. It is advantageous that the material projects further downstream in the transfer material transport direction than the most downstream portion of the guide base material in the transfer material transport direction (claim 6).

The image forming apparatus according to claim 1, 5 or 6, further comprising: a tangential plane at the most downstream portion of the transfer guide surface of the first guide in the transfer material transport direction;
It is advantageous to set the mounting position of the static elimination member so that the static elimination member is located in a space between the transfer material guide surface of the second guide and the tangential plane of the most upstream portion in the transfer material transport direction. (Claim 7).

Further, in the image forming apparatus according to any one of the first to seventh aspects, it is advantageous that the static elimination member comprises a static elimination brush extending in a direction transverse to a transfer material conveying direction. ).

Further, in the image forming apparatus according to any one of the first to seventh aspects, it is advantageous that the static elimination member comprises a static elimination needle extending in a direction transverse to a transfer material conveying direction (claim 9). ).

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a schematic sectional view showing an example of an image forming apparatus to which the present invention is applied, viewed from the front side. The image forming apparatus shown here reads a document image and performs a process based on the document image. It has a function of a copying machine for forming an image by an electrophotographic system and a function of a printer, but a function as a facsimile can be further added. Here, first, the configuration and operation common to each specific example directly related to the present invention described later will be clarified based on FIG.

In FIG. 1, an original (not shown) is placed on a contact glass 2 fixed on an upper portion of an image forming apparatus main body 1, and the original is illuminated by a light source 3 moving rightward in FIG. The reflected light image is reflected by the first mirror 4 moving rightward together with the light source 3,
After being reflected by the second and third mirrors 5 and 6 moving rightward at half the speed of the light, the light enters the reading device 7. The reading device 7 includes an image sensor (not shown) formed of, for example, a CCD for reading a reflected light image from a document,
It also has an imaging lens (not shown) for forming an optical image on this sensor.

A drum-shaped photosensitive member 14 which is an example of an image carrier rotatably supported by the image forming apparatus main body 1
Is driven to rotate clockwise in FIG. 1,
The surface of the photoreceptor 14 is uniformly charged to a predetermined polarity by a charging device 15, and the charged surface is irradiated with light-modulated laser light L emitted from the exposure device 8, whereby the photoreceptor 14 An electrostatic latent image is formed on the image. It is also possible to use an image carrier made of an endless belt-shaped photoconductor which is wound around a plurality of pulleys and driven to rotate.

The exposure apparatus 8 shown in FIG. 1 includes a scanning image forming lens system 1 including a rotary polygon mirror 9 for reflecting laser light emitted from a laser light source (not shown), an fθ lens, and the like.
0, mirror 1 for reflecting laser light passing through lens system 10
The laser beam L is formed on the photoreceptor 14. The laser light is optically modulated in accordance with the image signal read by the reading device 7, and an electrostatic latent image corresponding to the original image is formed on the surface of the photoconductor 14 irradiated with the laser light L. Is done.

The electrostatic latent image described above is
Is visualized as a toner image. The developing device 16 shown in FIG. 1 includes a developer case 18 containing a developer D and a developing roller 1 rotatably supported inside the developer case 18.
The developer is carried and conveyed on the peripheral surface of the developing roller 17 which is rotationally driven, and the electrostatic latent image formed on the photoreceptor 14 is visualized as a toner image by the conveyed developer. You. In the developing device 16 of the present embodiment, as the developer D, a powdery two-component developer having a toner and a carrier is used, but a one-component developer containing no carrier may be used. Further, a toner supply container 18A is attached to the developer case 18, and the toner T is stored therein. When the toner concentration of the developer D in the developer case 18 decreases, the toner supply roller 19 rotates to The toner T in the supply container 18A is supplied into the developer in the developer case 18.

On the other hand, a plurality of paper feed cassettes 20, 20A,
A transfer material P made of transfer paper, a resin sheet, or the like is fed from any one of the cassettes 20B in the direction of arrow A, and the transfer material P is aligned with the toner image on the photoconductor 14 by the registration roller pair 21. The photoconductor 14
The sheet is fed to a transfer section S between the transfer belt 22 and the transfer belt 22.

The endless transfer belt 22 is
3 and is driven in the direction of the arrow B, and is in contact with the surface of the photoconductor 14 at the transfer portion (transfer position) S. The transfer material P sent out by the registration roller pair 21 passes through a transfer portion S between the transfer belt 22 and the photoconductor 14 while being carried and conveyed by the transfer belt 22. At this time, a voltage having a polarity opposite to the polarity of the charged toner of the toner image on the photoconductor 14 is applied to the bias roller 25 disposed on the back surface side of the transfer belt 22.
As a result, a bias voltage having a predetermined polarity is applied to the transfer belt 22, and the toner image formed on the surface of the photoconductor 14 is electrostatically transferred on the surface of the transfer material P in the transfer unit S by the action. At least the surface portion of the transfer belt 22 in contact with the transfer material P has a volume resistivity of medium resistance (for example, 10%).
^{6 to} 10 ¹² Ωcm).

The transfer material P on which the toner image has been transferred is successively carried on the transfer belt 22 and conveyed in the direction of arrow B.
After leaving the transfer belt 22, the toner image passes through a fixing roller 30A of the fixing device 30 and a pressure roller 30B which is paired with the fixing roller 30A. At this time, the toner image is fixed on the transfer material P by the action of heat and pressure. You. Next, the transfer material P is transferred to the discharge roller pair 3
1 is discharged onto the discharge tray 32 as copy paper.

The transfer residual toner that has not been transferred to the transfer material P adheres to the surface of the photoreceptor after the transfer of the toner image. The transfer residual toner is removed by the cleaning device 33 for the carrier, and the surface of the photoreceptor is removed. Is cleaned. The surface of the photoreceptor after cleaning is initialized by receiving a charge removing action by a charge removing device 37 composed of a lamp, and the above-described operation is continuously performed.
The toner image is transferred onto the next transfer paper.

The carrier cleaning device 33 includes a cleaning member including a cleaning blade 34, a cleaning case 35, and a toner discharging member 36 disposed at the bottom of the cleaning case 35.
The cleaning blade 34 is made of an elastic material such as rubber, and extends in parallel with the photoconductor 14 over the entire image area in the axial direction of the photoconductor 14, that is, the area where the untransferred toner adheres. Is cleaning case 3
5 and the opposite end edge is the photosensitive member 1
4 is pressed against the surface, and the transfer residual toner attached to the surface is scraped off.

The drive roller 23, the driven roller 24, and the bias roller 25 around which the transfer belt 22 is wound are rotatably supported by a case 27. Transfer belt 22
Is slightly transferred to and adheres to the surface of the photoreceptor 14, and if left unattended, the toner becomes
Since the toner adheres to the back surface of the transfer material P sent to the transfer belt 22 and soils the transfer paper with toner, the toner adhered to the surface of the transfer belt 22 is removed by the belt cleaning device 26. The belt cleaning device 26 includes a cleaning member including a cleaning blade 28 pressed against the surface of the transfer belt 22;
It has a cleaning case 26A constituted by a part of the case 27 described above, and a toner discharge member 29 disposed at the bottom thereof. The cleaning blade 28
It is made of an elastic material such as rubber, and extends in parallel with the transfer belt 22 over the entire area of the transfer belt 22 to which the toner adheres, and its base end is fixed to the cleaning case 26A. The transfer belt 2 is at the leading edge
2 is pressed against the surface, and the toner adhering to the surface is scraped off.

The cleaning blades 28 and 3 of the belt cleaning device 26 and the carrier cleaning device 33 are provided.
Instead of 4, a cleaning member such as a fur brush or a cleaning roller may be used.

As described above, the image forming apparatus of the present embodiment is configured such that the transfer material P is formed of a material having a medium volume resistivity at least at the surface portion in contact with the transfer material P and passes through the transfer portion S. It has a transfer belt 22 that carries and conveys P, and by the action of a voltage applied to the transfer belt,
The toner image formed on the surface of the image carrier composed of the photoconductor 14 is electrostatically transferred to the surface of the transfer material P in the transfer section S, and the toner image transferred to the transfer material P is fixed to the fixing device 3.
It is configured to fix by 0.

Here, the transfer material P on which the toner image has been transferred from the surface of the photoreceptor 14 faces up with the surface carrying the toner image thereon, is carried on the transfer belt 22 as it is, and is conveyed as it is. The toner image is separated from the transfer belt 22 by the curvature separation at the position of the wound transfer belt portion, and is sent to the fixing device 30 with the surface carrying the toner image facing upward. At that time, the transfer material P separates from the surface of the transfer belt 22 in a charged state. Until the toner image on the transfer material P is fixed by the fixing device 30, the toner image adheres to the surface of the transfer material P mainly by only an electric coupling force. Therefore, when electric disturbance occurs in the transfer material P, the toner image on the transfer material P is disturbed, and an abnormal image such as toner dust occurs. The charging of the transfer material P is a factor. Specific examples include abruptly removing electricity from the transfer material P, and frictional charging caused by the transfer material slidingly contacting a transport guide or the like.
Therefore, it is necessary to gently remove the charge from the transfer material P separated from the transfer belt 22.

Therefore, in the first specific example of this embodiment,
2, the first guide 40 is disposed at a position downstream of the transfer belt 22 with respect to the transport direction of the transfer material P, and at a position further downstream of the first guide. A second guide 41 is disposed, and a charge removing member 42 is provided in a space between the first guide 40 and the second guide 41.
Is arranged. The first and second guides 40 and 41 and the charge removing member 42 are located upstream of the fixing device 30 in the transfer material transport direction. In the example of FIG. 1, the first and second guides 40, 41 are fixedly supported by support members 43, 44, respectively, and the charge removing member 42 is also fixedly supported by the support member 44. Further, although the charge removing member 42 shown in FIG. 2 is made of a charge removing brush, a charge removing member made of a charge removing needle can be used. The static elimination member may be a static elimination brush or a static elimination needle, which is the same in each specific example described later.

The neutralizing brush constituting the neutralizing member 42 is formed of a conductive brush. The neutralizing member 42 extends over the entire width of the transfer material P, and the neutralizing member 42 is electrically grounded. As shown in FIG. 3, the distal end of the charge removing member 42 is connected to the most downstream portion 40 of the first guide 40 in the transfer material transport direction.
A and the most upstream portion 41 of the second guide 41 in the transfer material transport direction
It is arranged so as to be farther from the transfer path of the transfer material by a distance E of 1 to 2 mm than a straight line C connecting to A.

The volume resistivity of the surface portion of the first guide 40 with which the transfer material P leaving the transfer belt 22 comes into contact is set to a medium resistance or more, that is, 10 ⁶ Ωcm or more. On the other hand, the second guide 41 may be conductive, insulative, or a medium resistor. In the illustrated example, the second guide 41 does not easily adhere to the zinc-treated steel sheet. Guide 41 made of plate material coated with resin
Is configured.

The transfer material P separated from the transfer belt 22 is first guided to the surface of the first guide 40, that is, the upper surface thereof, and then passes over the upper surface of the second guide 41, where the fixing roller 30A and the pressure roller It is sent during 30B. When the transfer material P passes over the first guide 40, the surface of the first guide 40 has an electrical characteristic of medium resistance or higher as described above. Not done. When the transfer material P passes between the first guide 40 and the second guide 41, the transfer material P is subjected to a charge removing operation by discharge by the charge removing member 42. That is, the transfer material P is moved from the back surface opposite to the front surface on which the toner image is formed on the charge removing member 4.
2 is subjected to non-contact static elimination. As described above, when the transfer material P passes through the first guide 40, the transfer material P is not positively discharged, and when the transfer material P passes through the charge removal member 42, the transfer material P becomes non-conductive. Since the contact is neutralized, the transfer material P is not sharply neutralized. Therefore, the unfixed toner image on the transfer material P is disturbed (toner dust).
Can be prevented, and a high-quality image can be obtained. In addition, when the transfer material is brought into contact with the charge removing member and the charge is removed from the transfer material, an abnormal image is likely to be generated due to uneven contact. However, depending on the configuration shown in FIG. Such a trouble does not occur.

Further, since the transfer material P is subjected to a charge removing operation while being supported by both the first guide 40 and the second guide 41, the transfer material P is transferred to the charge removing member 42 while being transported in a stable state. The distance from the material P can always be kept constant. Thus, the transfer material P can be uniformly discharged in a stable state, and the occurrence of an abnormal image can be prevented. Static elimination member 4
When the transfer material P is grounded and the transfer material P is subjected to non-contact charge elimination, the distance between the charge removing member 42 and the transfer material P needs to be reduced, and at the same time, the accuracy is also required. By discharging the transfer material P while supporting the transfer material P on the second guides 40 and 41, the above requirement can be satisfied without fail.

Further, since the charge removing member 42 is simply grounded and no voltage is applied thereto, there is no need to provide a high voltage power supply or a leak preventing means, and the configuration of the image forming apparatus can be simplified, The cost can be reduced.

When the first guide 40 is triboelectrically charged by contact with the transfer material P, and a large amount of electric charge is accumulated therein,
Since the toner image on the transfer material P may be disturbed by the action of the electric field due to this, the first guide 40
Is desirably formed of a member having a low capacitance and a medium resistance or more.

FIG. 4 shows a modification of the first embodiment when the charge removing member 42 comprises a charge removing needle. As shown in FIG. 5, the static elimination needle is composed of a large number of needles having sharp tips, and the interval H between the needles is, for example, 2 mm, and the height I is, for example, 3 m.
m, the radius J of the root portion is, for example, 0.5 mm, and the thickness is, for example, 0.1 mm. Such a static elimination needle is made of, for example, a conductive material such as stainless steel.

The other configuration shown in FIG. 4 is substantially the same as the configuration shown in FIG. 2, and the distal end of the static elimination member composed of the static elimination needle is connected to the most downstream portion of the first guide 40 and the second guide. Guide 41
There is no change in the distance from the transfer path of the transfer material by about 1 to 2 mm from the straight line connecting the uppermost stream of the transfer material, and the fact that the charge removing member 42 is grounded. In FIG.
Although the first guide 40 is fixedly supported on the upper end surface of the case 27, this is not an essential difference from the configuration shown in FIG.

As described above, in the image forming apparatus of the first specific example, the first guide 40 supporting the transfer material P after passing through the transfer belt and the first guide 40 And a second guide 41 disposed downstream of the transfer belt 2 and supporting the transfer material P after passing through the first guide.
2 is provided between the fixing device 30 and the fixing device 30, and is electrically non-contacted from the back surface of the transfer material P passing between the first guide 40 and the second guide 41.
2 and a first guide 4 with which the transfer material P contacts.
The volume resistivity of the surface portion of 0 is set to 10 ⁶ Ωcm or more.

The first and second guides 40 and 41 shown in FIGS. 2 to 4 are spaced apart from each other in the transfer material transport direction. As shown in FIG. 3, the height of the most downstream portion 40A of the first guide 40 is higher than the height of the most upstream portion 41A of the second guide 41 so that the second guide 41 can be transferred to and transported from the second guide 41. are doing. However, with this configuration, when the transfer material P to be conveyed comes into strong contact with the corner of the most downstream portion 40A of the first guide 40, and electric charges are accumulated in the first guide 40 due to the triboelectric charging. The toner image on the transfer material P may be disturbed by the action of the electric field. If the transfer belt 22 is not completely cleaned,
Although slightly, the toner adheres to the back surface of the transfer material P,
The transfer material P passes through the first guide 40. At this time, if the transfer material P strongly contacts the most downstream portion 40A of the first guide 40, the toner attached to the back surface of the transfer material is scraped off. The toner may reattach to the leading or trailing end of the transfer material, and the edge of the transfer material P may be stained with the toner.

Accordingly, in the second specific example shown in FIGS. 6 and 7, in the image forming apparatus of the first specific example, the first
A connecting portion 45 for connecting the first guide 40 and the second guide 41 in a state where a space between the guide 40 and the second guide 41, that is, the charge removing space S1 where the charge of the transfer material P is removed is left. Are provided, and the first guide 40 and the second guide 41 are integrated. In the example of FIG.
5 are provided, and a static elimination space S1 is defined therebetween. Other configurations are substantially the same as the first specific example. In the examples shown in FIGS. 6 and 7, the charge elimination brush is used as the charge elimination member, but a charge elimination member including a charge elimination needle may be used. This is the same in the examples shown in FIGS.

If the connecting portion 45 is provided as described above, the first
Even when the upper surfaces of the second guides 40 and 41 are continuously flush, the transfer material P can be transported without any trouble. That is,
As shown by an arrow in FIG.
Since it is possible to move from the first guide 40 to the second guide 41 while being guided by 5, the first and second guides 40 and 41 do not need to be provided with a large step as shown in FIG. As a result, the transfer material P does not come into strong frictional contact with the most downstream portion of the first guide 40, and the occurrence of the above-described problem can be prevented.

The first guide 40 and the second guide 41
Is small, the positional relationship between the charge removing member 42 and the transfer material P can be stabilized, and more stable charge removal of the transfer material can be performed.

It is preferable that the volume resistivity of the surface of the connecting portion 45 be equal to or more than 10 ⁶ Ωcm as in the case of the first guide 40.

If the connecting portion 45 is provided as described above, the connecting portion 45 may hinder the charge removing member 42 from removing the charge of the transfer material P. Therefore,
In the example shown in FIGS. 6 and 7, as clearly shown in FIG.
In addition to the configuration of the above-described second specific example, in a state where one transfer material P is simultaneously supported by the first guide 40 and the second guide 41, the transfer material P does not contact the connecting portion 45. Thus, the connecting portion 45 is formed. Connecting part 45
Of the first and second guides 40 and 41 in the vicinity thereof
Is set lower than the height of the transfer material guide surface. This is the third specific example. With this configuration, when the charge of the transfer material P is removed, the discharge can flow into the gap between the connection portion 45 and the transfer material P, and the charge removal function is deteriorated by the connection portion 45. Will be blocked.

As shown in FIGS. 10 and 11, when the connecting portion 45 is inclined with respect to the transfer direction B of the transfer material,
As shown by the arrow F in FIG. 12, any point of the transfer material P always passes through the static elimination space S1 between the first guide 40 and the second guide 41.
Therefore, there is no possibility that the static elimination function is reduced. This is the fourth
Is a specific example. In this case, the transfer material guide surfaces of the first guide 40, the connecting portion 45, and the second guide 41 are
As shown in FIG. 10 and FIG. 11, even in the flush state, the static elimination function does not decrease. By making the transfer material guide surface flat over the entire surface, the transfer material can be smoothly transported. Needless to say, the connecting portion 45 shown in FIGS. 10 and 11 is lowered below the transfer material guide surfaces of the first and second guides 40 and 41, similarly to the connecting portion 45 shown in FIGS. You can also.

As described above, the fourth embodiment is different from the second or third embodiment in that the connecting portion 45 extends obliquely with respect to the transfer direction of the transfer material P. It is characterized by.

FIG. 13 shows a fifth specific example. In this example, the static elimination member 42 is made of the static elimination needle shown in FIG. The distal end is arranged in a posture facing the static elimination space between the first guide 40 and the second guide 41. The static elimination member 42 is fixed on the end surface of the case 27, and the static elimination member 4
The spacer 46 is fixedly arranged on the second 2, and the first guide 40 is fixedly arranged thereon. At that time, the first
Of the guide 40 is bent downward, that is, in a direction away from the transfer material. Other configurations are not substantially different from the above-described first specific example.

When the first guide 40 is bent as described above, the bent portion and the transfer material P are smoothly contacted, and the most downstream portion of the first guide 40 and the transfer material P are connected. The above-mentioned problem caused by too strong contact can be prevented. In addition, the transfer behavior of the transfer material P supported by the first and second guides 40 and 41 is stabilized, and as a result, the positional relationship between the charge removing member 42 and the transfer material P is stabilized, and the transfer material P is more reliably secured. P can be uniformly discharged.

As described above, the fifth specific example is characterized in that, in the configuration of the first specific example, the downstream portion of the first guide 40 in the transfer material transport direction is bent downstream. I do.

FIGS. 14 and 15 show a sixth specific example. In this example, a base 47 is fixed to the upper end surface of the case 27, and a discharging member 42 made of a discharging needle is provided thereon. The first guide 40 is fixed
Guide base material 48 is fixed, and the guide base material 48
A sheet material 49 having an elasticity with a volume resistivity of 10 ⁶ Ωcm or more, for example, a resin sheet such as Mylar (trade name) is adhered and fixed on the substrate. The first guide 40 is constituted by the guide base material 48 and the sheet material 49. At this time, as in the example of FIG.
In FIG. 13, the downstream portion in the transfer material transport direction is bent downward, whereby the operation and effect described above with reference to FIG. 13 can be obtained.

The sheet material 49 projects further downstream than the most downstream portion of the guide base material 48 in the transfer material transport direction. With this configuration, the projecting length of the sheet material 49,
By appropriately selecting the hardness, thickness, and the like, the sheet material 49 can be used as a flexible guide, and the contact between the sheet material 49 and the transfer material P can be further reduced. The occurrence of an abnormal image due to strong contact between the first guide 40 and the transfer material P can be effectively prevented.

Further, a space is formed below the sheet material 49, so that a margin for arrangement of the charge eliminating member 42 disposed between the first guide 40 and the second guide 41 can be increased. That is, as shown in FIG. 16, if the sheet material 49 is not made to protrude, the distance from the leading end of the sheet material 49 to the charge removing member 42 is reduced.
Since the distance K along the end face of the guide base material 48 becomes short,
The charge of the transfer material P flows to the charge removing member 42 through a path corresponding to this distance, and the possibility of performing contact charge removal increases.
On the other hand, as shown in FIG. 15, when the sheet material 49 is made to protrude from the guide base material 48, the distance K from the leading end of the sheet material 49 to the static elimination member 42 along the end face of the guide base material 48 increases. Therefore, the transfer material P
Therefore, it is possible to eliminate the possibility that the electric charge moves directly to the charge eliminating member 42, and it is possible to reliably perform the non-contact charge removal.

As described above, the sixth example is different from the first or fifth example in the configuration of the first guide 40 in the first or fifth example.
Has a guide base material 48 and a sheet material 49 fixed to the upper surface of the guide base material 48, and the sheet material 49 is further transferred from the most downstream portion of the guide base material 48 in the transfer material transport direction. It is characterized by protruding downstream in the material transport direction.

FIGS. 17 and 18 show a seventh concrete example.
In this example, a static elimination member 42 composed of a static elimination needle is disposed below the first guide 40 via a spacer 50,
The static elimination member 42 is fixed to the upper end surface of the case 27. Here, the feature of the seventh specific example is shown in FIG.
As shown in FIG. 8, in addition to the configuration of the first, fifth or sixth specific example described above, a plane in the tangential direction of the most downstream portion 40A in the transfer material transport direction on the transfer material guide surface of the first guide 40 The charge removing member 42 is positioned such that the charge removing member 42 is located in a space sandwiched between L1 and a plane L2 in the transfer material guide surface of the second guide 41 in the tangential direction of the most upstream portion 41A in the transfer material transport direction. The point is that the mounting posture is set.

A test was performed to compare the occurrence of abnormal images between the case where the charge removing member 42 was disposed in the position shown in FIG. 4 and the case where the charge removing member was disposed in the position shown in FIG. In order to make it easier for abnormal images to occur,
The developing conditions are set so that a larger amount of toner than usual is on the transfer material P, and at the same time, 0.2 mm
The comparison was made with images of approximately black and white lines (alternate lines of 0.2 mm white and 0.2 mm black). As a result, less toner dust occurs when the charge eliminating member 42 is arranged as shown in FIG. 18 than when the charge eliminating member is arranged almost perpendicular to the transfer material as shown in FIG. And good images were obtained. However, when the amount of toner on the transfer material was returned to the normal state, no abnormal image was generated even when the charge removing member 42 shown in FIG. 4 was used.

From the above results, when the configuration of the seventh embodiment shown in FIGS. 17 and 18 is employed, the effect of eliminating the charge of the transfer material is further improved, and the transfer material and various external temperature and humidity conditions are improved. It can be understood that a high-quality image can be obtained with a margin. The seventh specific example is also employed in the examples shown in FIGS.

As described above, in any of the above-described embodiments, a static elimination member including a static elimination brush or a static elimination member including a static elimination needle can be used. When the discharging member is made of a brush extending in the lateral direction, the discharging member is soft, so that the discharging member can be easily handled when the device is mounted on the image forming apparatus main body or during maintenance. Conversely, when the static elimination member is formed of a static elimination needle extending in the transverse direction to the transfer material transport direction, an advantage that the occurrence of abnormal images due to abnormal discharge can be reduced more reliably than when a static elimination brush is used is obtained. Can be

The present invention can also be applied to various image forming apparatuses other than the type shown in FIG. 1. For example, the present invention is applied to an image forming apparatus in which an image carrier is formed by an intermediate transfer member for primarily transferring a toner image from a photosensitive member. The present invention can be applied without any problem.

[0061]

According to the image forming apparatus of the first aspect, the transfer material immediately after separation from the transfer belt is not positively discharged, and the transfer material is transferred between the first and second guides. Since non-contact static elimination is performed by the static elimination member, it is possible to eliminate the defect seen in contact static elimination. In addition, since the charge is removed while the transfer material is supported by the first guide and the second guide, the distance between the transfer material and the charge removing member can be maintained substantially constant at all times, and stable charge removal can be performed.

Since no voltage is applied to the neutralizing member,
A high-voltage power supply and leak prevention means are not required, and cost can be reduced.

According to the image forming apparatus of the second aspect,
It is possible to suppress occurrence of an abnormal image due to increased contact between the transfer material and the first guide.

According to the image forming apparatus of the third or fourth aspect, it is possible to prevent a reduction in the charge eliminating function due to the provision of the connecting portion.

According to the image forming apparatus of the fifth aspect,
It is possible to suppress occurrence of an abnormal image due to increased contact between the transfer material and the first guide.

According to the image forming apparatus of the sixth aspect,
Since the sheet material of the first guide protrudes from the guide base material, the contact between the first guide and the transfer material is smoothed, and the abnormal image due to the increased contact between the transfer material and the first guide. Can be suppressed.

According to the image forming apparatus of the seventh aspect,
The transfer material can be more efficiently discharged.

According to the image forming apparatus of the present invention,
Handling of the static elimination member becomes easy.

According to the image forming apparatus of the ninth aspect,
It is possible to more stably remove the charge of the transfer material.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an overall configuration of an image forming apparatus.

FIG. 2 is an enlarged view clarifying a configuration for removing a transfer material by a charge removing member.

FIG. 3 is an enlarged explanatory view of FIG. 2;

FIG. 4 is a view similar to FIG. 2, showing another example.

FIG. 5 is an enlarged view of a static elimination needle.

FIG. 6 is a view similar to FIG. 2, but showing still another example.

FIG. 7 is a perspective view for clarifying a connecting portion shown in FIG. 6;

FIG. 8 is a cross-sectional view illustrating an operation of the connecting portion shown in FIG.

FIG. 9 is a cross-sectional view showing details of a connecting portion shown in FIG. 7;

FIG. 10 is a view similar to FIG. 2, but showing still another example.

FIG. 11 is a cross-sectional view illustrating an operation of the connecting portion shown in FIG.

FIG. 12 is a view for explaining the operation of the connecting portion shown in FIG. 11;

FIG. 13 is a view similar to FIG. 2, but showing still another example.

FIG. 14 is a view similar to FIG. 2, but showing still another example.

FIG. 15 is a partially enlarged view of FIG. 14;

FIG. 16 is a diagram illustrating a problem when a sheet material is protruded.

FIG. 17 is a view similar to FIG. 2, but showing still another example.

18 is a partially enlarged view of FIG.

[Explanation of symbols]

 Reference Signs List 22 Transfer belt 30 Fixing device 40 First guide 40A Most downstream part 41 Second guide 41A Most upstream part 42 Static elimination member 45 Connecting part 48 Guide base material 49 Sheet material L1 Plane L2 Plane P Transfer material S Transfer part S1 Static elimination space

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Ichiro Komuro 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company (72) Inventor Hiroshi Saito 1-3-6 Nakamagome, Ota-ku, Tokyo Share F-term in Ricoh Company (reference) 2H032 AA05 BA05 BA18 BA21 BA23 BA29 CA04 DA16 2H033 AA01 BA08 BB01 BB28

Claims (9)

[Claims] 1. A transfer belt, which is formed of a material having at least a surface resistivity in contact with the transfer material and has a medium volume resistivity and carries and conveys the transfer material so as to pass through a transfer portion. Image formation in which the toner image formed on the surface of the image carrier is transferred to the surface of the transfer material in the transfer section by the action of the voltage applied to the transfer member, and the toner image transferred to the transfer material is fixed by a fixing device. In the apparatus, a first guide that supports the transfer material after passing the transfer belt and a transfer material that passes through the first guide and that is disposed downstream of the first guide in a transport direction of the transfer material. A second guide to be supported is provided between the transfer belt and the fixing device, and performs non-contact static elimination from the back surface of the transfer material passing between the first guide and the second guide. Grounded Provided electroconductive member, the first of the transfer material is in contact
Wherein the volume resistivity of the surface portion of the guide is set to 10 ⁶ Ωcm or more. 2. A connecting portion for connecting the first guide and the second guide in a state where a static elimination space is left between the first guide and the second guide. Image forming apparatus. 3. The connecting portion according to claim 2, wherein one transfer material is supported by the first guide and the second guide, and the connecting portion is formed such that the transfer material does not contact the connecting portion. The image forming apparatus as described in the above. 4. The image forming apparatus according to claim 2, wherein the connecting portion extends obliquely with respect to a transfer material transport direction. 5. The image forming apparatus according to claim 1, wherein a downstream portion of the first guide in a transfer material transport direction is bent downward. 6. The first guide has a guide base material and a sheet material fixed to an upper surface of the guide base material, and the sheet material is the most downstream portion of the guide base material in the transfer material transport direction. 6. The image forming apparatus according to claim 1, wherein the image forming apparatus further protrudes further downstream in the transfer material transport direction. 7. A tangential plane on the transfer material guide surface of the first guide in the tangential direction at the most downstream portion in the transfer material transport direction, and a tangential direction on the transfer material guide surface of the second guide in the most upstream portion in the transfer material transport direction. The image forming apparatus according to claim 1, wherein the mounting position of the charge removing member is set such that the charge removing member is located in a space sandwiched between the flat surface and the flat surface. 8. The image forming apparatus according to claim 1, wherein said static elimination member comprises a static elimination brush extending in a direction transverse to a transfer material conveying direction. 9. The image forming apparatus according to claim 1, wherein said static elimination member comprises a static elimination needle extending in a direction transverse to a transfer material transport direction.