JP5633151B2 - Transfer device and image forming apparatus - Google Patents

Description

  The present invention relates to a transfer device and an image forming apparatus, and more particularly to a jam clearing mechanism when a jam occurs on a recording paper used as one of recording media.

  In an image forming apparatus such as a copying machine, a printer, a facsimile machine, or a printing machine, an electrostatic latent image formed on a photosensitive member as a latent image carrier is subjected to visible image processing by a developing device, and a visible image is recorded. A recording output can be obtained by transferring to paper or the like which is one of the media.

  An image forming apparatus has a method of forming a full color image as well as a single color image on paper or the like. When full color image formation is performed, each color (for example, yellow, magenta, cyan, It is known that a visible image (such as black) is formed, these visible images are transferred onto an intermediate transfer member, and then transferred onto a recording sheet to obtain a full color image.

When the recording paper on which the images superimposed on the intermediate transfer member are collectively transferred is fed from the paper feeding device, the registration timing is set before reaching the batch transfer position, and the recording paper is fed out toward the batch transfer position.
As a configuration for setting the registration timing, a registration roller composed of a pair of rollers facing each other across the conveyance path of the recording paper is used.
The registration roller is configured so that the positional relationship between the leading edge of the image to be collectively transferred and the leading edge in the conveyance direction of the recording paper is adjusted by controlling the rotation start timing.

By the way, the recording paper, like the registration rollers, is nipped and conveyed by a pair of rollers facing each other across the conveyance path. However, if there is a warp or skew, the recording paper collides with the roller in the middle of the conveyance path and is prevented from proceeding. This can cause paper jams, so-called jams.
Therefore, when jamming occurs at the position of the roller used as the conveying member, as a configuration to eliminate this, the recording paper sandwiched between the rollers is fed out to the position where it can be picked up from the outside as follows. A configuration is proposed.
In the above-described configuration, a roller rotation operation knob is provided on a roller shaft equipped with a gear meshing with a gear interlocking with the drive mechanism at the shaft end, and the shaft end side on which the rotation operation knob is located can be opened and closed. A structure has been proposed in which the gears can be engaged and released by interlocking movement in the axial direction, and the roller is rotated using a rotation operation knob in the released state. (For example, patent document 1).

  As another configuration, a knob that can be engaged and disengaged is provided at the roller shaft end, and the knob and the roller shaft can be linked via a gear that meshes when the knob is pulled toward the outside of the shaft end. A configuration is proposed in which the transmission of the driving force transmission mechanism to the roller is released by a switch provided when the knob is pulled in the above-described direction (for example, Patent Document 2).

As another configuration, a roller rotation operation knob is provided on the roller shaft equipped with a gear that meshes with the gear interlocking with the drive mechanism, and the shaft end side where the rotation operation knob is located can be opened and closed. The gears can be meshed and disengaged by being moved in the axial direction in conjunction with a door, and the roller can be rotated using a rotation operation knob in the disengaged state (for example, Patent Document 2).
In the configurations disclosed in each of these patent documents, the roller can be rotated using the knob in a state where the transmission of the driving force is released by pulling the knob toward the outside of the shaft end.

In any of the configurations disclosed in each of the above patent documents, it is assumed that the transmission of the driving force to the roller is canceled in order to eliminate the jam.
For this reason, a clutch mechanism or the like for connecting / disconnecting the driving force is required, resulting in a complicated configuration.
In addition, the rotation operation of the roller at the time of jam removal requires a plurality of operations, i.e., release of driving force transmission and rotation operation of the roller shaft, and the work for jam removal becomes complicated.

  The configuration disclosed in Patent Document 1 is simpler than the configuration disclosed in Patent Document 2 in that the roller shaft is moved in the axial direction in conjunction with the opening / closing operation of the door that can be opened / closed. Since the meshing operation of the gears performed after the cancellation requires the meshing alignment of the clutch, it may be difficult to close the door.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a transfer device and an image forming apparatus having a configuration capable of eliminating a jam by a simple operation without complicating the configuration in view of the above-described problems in the conventional jam resolution. is there.

In order to achieve the above object, the present invention comprises the following arrangement.
(1) An image carrier and a pair of rollers facing each other across a conveyance path of a recording sheet onto which an image from the image carrier is transferred, toward a transfer position of the image carried on the image carrier. A conveying member composed of a pair of rollers capable of nipping and conveying a recording sheet, and one of the pair of rollers equipped on the conveying member can be brought into contact with and separated from another roller facing the roller. In the transfer device in which the swingable unit to be supported is provided on the cover side that forms the openable / closable outer shell of the housing body,
The unit is provided in a state which swings by its own weight in conjunction with the said cover rotation axis of said one roller of the pair of rollers as a fulcrum is opened,
The rotational axis of the one roller of the pair of rollers, spaced from each other from the pair of said one roller and a state in which said one other roller is brought into contact with each other opposed thereto of the roller depending on the swing amount of the unit in the direction to swing by rotating said one roller of the pair of rollers in nip conveyance direction of the recording sheet, to which said one roller of the pair of rollers A one- way clutch that idles one of the rollers in response to the unit swinging in a direction in which the other roller facing each other approaches each other ;
The one of the pair of rollers is configured to record the recording when the one roller of the pair of rollers and the other roller facing the roller abut each other when the unit swings. A transfer device characterized in that a rotation amount capable of pulling out a leading end portion of a sheet from a corresponding contact position is set.

(2) (1) Symbol in the transfer device of the mounting,
The one roller of the pair of rollers supported by the unit is given a habit of being brought into contact with the other roller facing the roller, and the unit reaches a predetermined swing angle. A pressure release member for releasing the contact habit is provided, and the pressure release member has a cam profile that changes a distance between the opposing surfaces of the image carrier and the transfer member according to a swing angle of the unit. A transfer device characterized in that a cam is used.

(3) In the transfer device according to (2),
The pressure release member is based on the cam profile, and when the unit is swung, the distance between the opposed shafts of the rollers corresponds to one roller of the roller pair corresponding to the non-swinging position and the other facing the other. A transfer device characterized in that the rollers are made larger than when the rollers are in contact with each other to separate the rollers.

(4) In the transfer device according to (2) or (3),
When the pressure release member reaches a predetermined swing angle of the unit, the distance between the opposing shafts of the one roller of the pair of rollers and the other roller facing the roller becomes the maximum. A transfer device characterized by having a configuration.

( 5 ) In the transfer device according to (1),
A transfer device, wherein a belt-like transfer member is used as the image carrier.

( 6 ) In the transfer device according to (1),
2. A transfer apparatus according to claim 1, wherein a belt-like photoconductor used in an image forming unit is used as the image carrier.

( 7 ) An image forming apparatus using the transfer device according to any one of (1) to ( 6 ).

According to the present invention, one roller rotates in the nipping / conveying direction of the recording sheet according to the swing of the unit in the conveying member provided with the rollers facing each other across the conveying path of the recording sheet, Since the recording sheet is rotated in the nipping / conveying direction according to the amount of rocking of the unit, even if it is desired to cause a jam on the recording sheet at the position where the conveying member is arranged, only the rocking operation of the unit is required. It is possible to feed the leading edge of the recording sheet to a position where it can be easily grasped by hand.
Further, one roller provided on the unit side is separated by maximizing the distance between the opposing shafts with the roller facing the one roller when the unit exceeds a predetermined swing angle by the pressure release member. Therefore, the clamping pressure from the roller to the recording sheet causing the jam is eliminated, and the jam can be easily eliminated.

1 is a schematic diagram illustrating an image forming apparatus using a transfer device according to an embodiment of the present invention. It is a schematic diagram for demonstrating the principal part structure of the transfer apparatus by this invention Example. It is a schematic diagram for demonstrating the driving force transmission mechanism of the conveyance member used for the principal part structure shown in FIG. FIG. 2 is a schematic diagram for explaining the characteristics of toner used in the image forming apparatus shown in FIG. 1. FIG. 6 is a schematic diagram for explaining a partial modification of the image forming apparatus illustrated in FIG. 1. It is a schematic diagram for demonstrating the principal part modification of the structure shown in FIG. It is a schematic diagram for demonstrating the modification regarding the driving force transmission mechanism shown in FIG.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described with reference to embodiments shown in the drawings.
FIG. 1 is a diagram showing an image forming apparatus to which a transfer apparatus according to the present invention is applied. An image forming apparatus 1000 shown in FIG. 1 is a color printer using a tandem system.
In FIG. 1, the image forming apparatus is intended for an intermediate transfer belt 5 </ b> A on which an image at an image forming station, which will be described later, is primarily transferred sequentially as an image carrier.

  In FIG. 1, an image forming station for each color along the extended surface of the intermediate transfer belt 5A used as an intermediate transfer member (for convenience, image forming stations for yellow, magenta, cyan, and black, which are complementary color toners, and processes described later). The cartridges are collectively indicated by symbols Y, M, C, and K).

  The image forming station includes a process cartridge having the same configuration. The process cartridge includes a photosensitive drum 1 and a charging device 2 and a writing device arranged around the photosensitive drum 1 (for the sake of convenience, writing light is indicated by L), A developing device 3 and a cleaning device 4 are provided. In FIG. 1, the reference numerals of the respective devices provided in the respective process cartridges are added with the reference numerals of the respective colors.

In the process cartridge, the photosensitive drum 1 is uniformly charged by the charging device 2, and an electrostatic latent image corresponding to the image information is formed by a writing operation from the writing device (L).
The electrostatic latent image formed on the photosensitive drum 1 is visualized by toner supplied from the developing device 3 and is transferred to an intermediate transfer belt 5A used as a visible image carrier in a transfer device 5 described later. The primary transfer is performed by receiving a transfer bias from the transfer roller 6 as a primary transfer device.
At the time of full color image formation, the visible images formed at the respective image forming stations are sequentially transferred onto the intermediate transfer belt 5A and superimposed.

  After the transfer, the photosensitive drum 1 is freed of residual toner by a cleaning blade 4A provided in the cleaning device 4 and is uniformly charged by the charging device 2 to be ready for the next image forming process.

The transfer device 5 includes an intermediate transfer belt 5A that is wound around a plurality of rollers 5B, 5C, 5D, and 5E, and a primary transfer roller 6 that faces each photosensitive drum with the intermediate transfer belt 5A interposed therebetween. ing.
In the configuration shown in FIG. 1, the intermediate transfer belt 5A is driven by a driving roller using one of a plurality of rollers, and a process speed of, for example, a moving speed of 150 mm / sec is set, and the surface of the intermediate transfer belt 5A extends in the direction indicated by the arrow. Is supposed to move.

  Among the rollers around which the intermediate transfer belt 5A is wound, the roller denoted by reference numeral 5B is used as the above-described drive roller and a secondary transfer device used as a secondary transfer device facing the intermediate transfer belt 5A. It is used as a backup roller for the roller 7. A roller denoted by reference numeral 5C is used as a tension roller that is urged in an extending direction by an elastic body such as a spring (not shown).

  A transfer roller 6 serving as a primary transfer device is biased toward the photosensitive drum 1 by an elastic body 6A such as a spring, and a visible image is transferred to the intermediate transfer belt 5A by a transfer bias fed from a bias power source 8. It is designed to transcribe. The primary transfer bias used in the configuration shown in FIG. 1 is, for example, + 1800V. A secondary transfer bias is also applied to the secondary transfer roller 7 by power supply from the bias power source 10.

The intermediate transfer belt 5A is composed of PVDF (vinylidene fluoride), ETFE (ethylene-tetrafluoroethylene copolymer), PI (polyimide), PC (polycarbonate) or the like in a single layer or a plurality of layers, such as carbon black. The conductive material is dispersed, and the volume resistivity is adjusted to be in the range of 10 ⁸ to 10 ¹² Ωcm, and the surface resistivity is adjusted to be in the range of 10 ⁹ to 10 ¹³ Ωcm. If necessary, a release layer may be coated on the surface of the intermediate transfer belt 10. Materials used for the coating include ETFE (ethylene-tetrafluoroethylene copolymer), PTFE (polytetrafluoroethylene), PVDF (vinylidene fluoride), PEA (perfluoroalkoxy fluororesin), FEP (four-fluorocarbon). Fluorine resin such as ethylene fluoride-propylene hexafluoride copolymer) or PVF (vinyl fluoride) can be used, but is not limited thereto.

  The method for manufacturing the intermediate transfer belt 5A includes a casting method, a centrifugal molding method, and the like, and the surface thereof may be polished if necessary. If the volume resistivity of the intermediate transfer belt 5A exceeds the above-mentioned range, it is not preferable because various power consumptions at the power source increase due to an increase in bias necessary for transfer, so that it is limited to the above-mentioned range. desirable. In addition, since the charging potential of the intermediate transfer belt 10 becomes high and self-discharge becomes difficult in the transfer process, the transfer paper peeling process, etc., it is necessary to provide a static eliminating means. Also, if the volume resistivity and surface resistivity are below the above ranges, the charge potential decays quickly, which is advantageous for static elimination by self-discharge, but toner scatter occurs because the current during transfer flows in the surface direction. End up. Accordingly, the volume resistivity and surface resistivity of the intermediate transfer belt 10 in the present invention are preferably within the above ranges. The volume resistivity and the surface resistivity were measured by connecting an HRS probe (inner electrode diameter 5.9 mm, ring electrode inner diameter 11 mm) to a high resistivity meter (manufactured by Mitsubishi Chemical Corporation: Hiresta IP). A measured value 10 seconds after applying a voltage of 100 V (surface resistivity is 500 V) to the front and back of the film was used.

The intermediate transfer belt 5 </ b> A is configured such that the residual toner is removed by the belt cleaning device 11 when all the transferred images have been subjected to the secondary transfer.
The cleaning device 11 includes a cleaning blade 11A made of an elastic material such as urethane rubber that comes into contact with the intermediate transfer belt 5A. The cleaning blade 11A can be contacted and separated by a swingable blade holder (not shown). The toner remaining on the intermediate transfer belt 5A is dammed up and cleaned by contacting the toner.
Instead of the cleaning blade, it is also possible to use a conductive brush or roller. By applying a bias, the toner that is electrostatically attached to the intermediate transfer belt 5A can be collected.
Although not shown, the toner collected from the intermediate transfer belt 5A is conveyed to the back side of the apparatus by a conveying member provided in the cleaning apparatus and is dropped downward by gravity. A toner collection bottle is disposed at a position where the toner falls, and although not shown, the toner collection bottle is provided with a fullness detection sensor so that it can be monitored so as to prompt replacement when full.

A lubricant application device 13 is provided in the vicinity of the belt cleaning device 11 in order to prevent rubbing damage by the cleaning blade 11A and to improve toner removal performance.
As shown in FIG. 1, the lubricant application device 13 scrapes the lubricant 13A by rotating while contacting the solid lubricant 13A and the solid lubricant 13A, and removes the scraped lubricant 13A on the surface of the intermediate transfer belt 5A. An application brush 13B for application is provided.

  In this embodiment, a fatty acid metal salt having a linear hydrocarbon structure is used as the lubricant. The fatty acid metal salt contains at least one fatty acid selected from stearic acid, palmitic acid, myristic acid and oleic acid, and at least one metal selected from zinc, aluminum, calcium, magnesium and lithium The fatty acid metal salt containing is mentioned. Among them, zinc stearate is the most preferable material in terms of cost, quality stability, and reliability because it is produced on an industrial scale and has been used in many fields. However, the higher fatty acid metal salt generally used industrially is not a single compound composition of its name, but includes other fatty acid metal salts, metal oxides, and free fatty acids that are more or less similar. Fatty acid metal salts are no exception.

  These lubricants 13A are supplied in the form of powder in small amounts. As a specific method, the lubricant 13A is lubricated solidly on the block by a lubricant application means such as the illustrated application brush 13B. There are a method of scraping and applying the agent, a method of supplying the toner by external addition, and the like. However, when supplying lubricant externally to the toner, the supply amount depends on the output image area and cannot always be supplied to the entire belt surface. When the lubricant is to be supplied stably, the method of scraping and applying the solid lubricant with a brush as described above is preferable.

  The application brush 13B is in contact with the solid lubricant 13A with a force of 1N to 4N by a pressure urging means (not shown). The width of the solid lubricant 13A is wider than the image width, and is set to 304 mm or more in this embodiment. Further, the width of the application brush 13B is made larger than the width of the solid lubricant 13A in order to enable uniform contact with the solid lubricant 13A.

On the other hand, the secondary transfer roller 7 is configured by coating an elastic body such as urethane adjusted to a resistance value of 10 ⁶ to 10 ¹⁰ Ω with a conductive material on a metal core such as SUS. .
Here, if the resistance value of the secondary transfer roller 7 exceeds the above range, it becomes difficult for the current to flow. Therefore, a higher voltage must be applied in order to obtain a required transfer property, resulting in an increase in power supply cost. . In addition, since a high voltage is applied, a discharge occurs in the gap before and after the transfer portion nip, so that white spots are lost due to the discharge on the halftone image. On the contrary, if the resistance value of the secondary transfer roller 7 is below the above range, the transferability between the multi-color image portion (for example, three-color superimposed image) and the single-color image portion existing on the same image cannot be achieved.

This is because the resistance value of the secondary transfer roller 7 is low, so that a sufficient current flows to transfer the monochrome image portion at a relatively low voltage. However, it is optimal for the monochrome image portion to transfer the multiple color image portion. Since a voltage value higher than the voltage is required, setting a voltage that can transfer a plurality of color image portions causes an excessive transfer current in a single-color image, resulting in a reduction in transfer efficiency. The resistance value of the secondary transfer roller 7 is measured by installing the secondary transfer roller 7 on a conductive metal plate and applying a load of 4.9 N on one side (total of 9.8 N on both sides) to both ends of the core metal. In this state, it was calculated from the value of the current flowing when a voltage of 1000 V was applied between the metal core and the metal plate. The secondary transfer roller 7 is given a driving force by a driving gear (not shown), and its peripheral speed is adjusted to be substantially the same as the peripheral speed of the intermediate transfer belt 10. The secondary transfer is controlled by a constant current, and in this embodiment, the set value is +30 μA.

The recording sheet S used as the recording sheet is conveyed by the paper feeding roller 14 and the transfer sheet conveying roller 15, and the leading end portion of the four-color superimposed image formed on the intermediate transfer belt 5A by the registration roller 16 reaches the secondary transfer position. Paper is fed according to the timing. The recording sheet S on which the four-color superimposed image has been transferred is conveyed to the fixing device 19 along the guide member 30 serving as a transfer outlet and a fixing inlet guide, and is fixed by the fixing device 19 and then discharged by the paper discharge roller 20. Is done.
Although not shown, it is also possible to remove the toner adhering to the back surface of the transfer paper by discharging the recording paper S after transfer.

The transfer device, which is a feature of the present invention, will be described for the configuration of the image forming apparatus as described above, and the configuration of the secondary transfer device including the registration roller 16 will be described.
The secondary transfer device includes a secondary transfer roller 7 as a main part, and a unit 31 including one roller 16A of the first and second rollers 16A and 16B facing each other across the conveyance path of the recording paper S. It has.

FIG. 2 is a schematic diagram illustrating the configuration of a secondary transfer apparatus (indicated by reference numeral 100 for convenience).
In FIG. 2, the secondary transfer apparatus 100 is provided so as to cover it, and is interlocked with an opening / closing operation of an openable / closable cover 101 that forms an outline of the image forming apparatus.
That is, the cover 101 can be opened with the upper end portion opened by the fulcrum shaft 101A supported on the image forming apparatus main body side, and the secondary transfer roller 7 in FIG. A guide member 102 that urges the unit 31 so as to abut on the 5A side is provided. The guide member 102 is given a habit of being constantly displaced toward the unit 31 as shown by an arrow S in FIG. 2A by a pressing biasing means such as a spring (not shown). It can come into contact with the unit 31 as a guide part at the time. The urging force of the pressing urging means is set to a force that does not prevent the unit 31 from rotating using its own weight in conjunction with the opening of the cover 101. As a result, the unit 31 can swing using its own weight as shown in FIG. 2 (B) in conjunction with the opening of the cover 101 from the closed position of the cover 101 shown in FIG. 2 (A). As shown in FIG. 2C, when the cover 101 is opened to a predetermined position, the cover 101 is stopped at the position of the maximum swing angle by a locking portion provided on the apparatus side (not shown).

  The unit 31 can swing on the image forming apparatus main body side with the rotation shaft of one of the registration rollers 16 composed of a pair of rollers 16A and 16B facing each other across the conveyance path of the recording paper S as a fulcrum. It is supported by. A secondary transfer roller 7 is supported on the swing end side of the unit 31.

  Of the rollers constituting the registration roller 16, the roller 16B facing the one roller 16A is given a habit of abutting toward the one roller 16A by an urging means (not shown). Accordingly, the roller 16B facing the one roller 16A is a member that can change the distance between the opposed shafts by moving in the contact / separation direction with respect to the one roller 16A against urging.

  The unit 31 is given a habit of swinging clockwise in FIG. 2 using a not-shown string spring or the like, and this swing is prevented when the cover 101 is in the closed position. The unit 31 may be rotated by inserting a hand through a gap generated when the cover 101 is opened, without using the clockwise biasing of the unit 31 as described above. In any case, the unit 31 can swing clockwise by its own weight.

One roller 16A of the rollers constituting the registration roller 16 can rotate in the nipping and conveying direction of the recording paper S in conjunction with the swing of the unit 31, that is, when the cover 101 is opened. Hereinafter, this configuration will be described.
Among the rollers constituting the registration roller 16, a rotation shaft of one roller 16A is equipped with a one-way clutch that transmits a rotational force only in a direction in which the recording paper S can be pinched and conveyed. Although the details of the one-way clutch are not described, the one-way clutch includes a base portion fixed to the unit 31 side and a rotating body that is inserted through the rotating shaft of one roller 16A, and the recording paper S is interposed between the base portion and the rotating body. A mechanism for rotating the rotating shaft of one roller 16A only in the nipping and conveying direction is provided.

FIG. 3 shows the direction in which the rotation shaft can rotate. In FIG. When the unit 31 swings, the rotating shaft rotates idle.
As a result, when the unit 31 swings in the opening direction of the cover 101, the swinging direction is clockwise as shown in FIG. Can rotate clockwise. In this case, the rotation amount of one roller 16 </ b> A corresponds to the swing amount of the unit 31.

On the other hand, the roller pair constituting the registration roller 16 is brought into contact with and separated from the unit 31 according to the swinging of the unit 31. In particular, when the cover 31 is opened, one roller 16A is separated from the opposite roller 16B. Is provided.
That is, in the unit 31, the pressure release member 103 formed of a cam fixed to the unit 31 is opposed to the rotation shaft of the roller 16 </ b> B that is opposed to one roller 16 </ b> A of the roller pair constituting the registration roller 16. It is in contact.

As shown in a balloon in FIG. 2A, the cam 103 causes the rollers to contact each other until the unit 31 reaches a predetermined swing angle (θ), and when the predetermined swing angle is exceeded, one roller 16A. Is provided with a cam profile that increases the distance between the opposed shafts by separating the roller 16B facing the roller 16B from the one roller 16A.
When the roller 16B facing one roller 16A is pushed by the cam profile of the pressure release member 103, the roller 16B moves in a direction away from the one roller 16A against its own behavior.

The predetermined swing angle (θ) described above is an angle smaller than a maximum opening angle (an angle indicated by β in FIG. 2C) when the cover 101 is opened, and this maximum opening angle (β) is This corresponds to the angle at which the guide member 102 is positioned at a position where the unit 31 can be held in a substantially horizontal position.
Accordingly, one roller 16A of the roller pair constituting the registration roller 16 is in contact with the other roller 16B in the nipping and conveying direction of the recording paper S until reaching a predetermined swing angle (θ). Since it rotates, the recording paper can be fed out by the registration roller 16.
In the present embodiment, as the above-described predetermined swing angle (θ), when the leading end of the recording sheet S is jammed at the position of the registration roller 16, the leading end of the recording sheet can be manually pulled out from the position. The angle is set so that the rotation amount of one roller 16A can be obtained. In FIG. 2, for the sake of convenience, the state where the pressure release member 103 is opposed to the peripheral surface of the other one roller 16B is shown. However, actually, as described above, the other roller 16B has the other roller 16B. It is provided corresponding to the rotation axis.

Since the present embodiment is configured as described above, as shown in FIG. 2, when a jam occurs on the recording paper S in the secondary transfer apparatus, the unit 31 is interlocked by opening the cover 101. Rock it.
When the unit 31 swings in the opening direction of the cover 101, one of the rollers constituting the registration roller 16 holds the recording paper S with a rotation amount corresponding to the swinging amount of the unit 31 via a one-way clutch. Rotates in the transport direction.

  Since the rollers are in contact with each other until the swing angle of the unit 31 reaches a predetermined angle (θ), the recording paper S is fed out, and the leading end can be fed out to a position where it can be taken out by hand.

  On the other hand, when the unit 31 exceeds a predetermined swing angle (θ), the pressure release member 31 separates the roller 16B facing the roller 16A from the roller 16A, and the distance between the opposing axes of the rollers is increased. Accordingly, since the rollers are separated from each other, the clamping pressure on the recording paper S is eliminated, so that the rollers can be taken out smoothly.

Next, the characteristics of the toner used in the image forming apparatus shown in FIG. 1 will be described.
The toner used in this embodiment is a polymerized toner produced by a polymerization method.
Further, the shape factor SF-1 of the toner used in this configuration is preferably in the range of 100 to 180, and the shape factor SF-2 is preferably in the range of 100 to 180.
FIG. 4 is a diagram schematically showing the shape of the toner in order to explain the shape factor SF-1 and the shape factor SF-2.

The shape factor SF-1 indicates the ratio of the roundness of the toner shape and is represented by the following formula (1). This is a value obtained by dividing the square of the maximum length MXLNG of the shape formed by projecting the toner on a two-dimensional plane by the figure area AREA and multiplying by 100π / 4.
SF-1 = {(MXLNG) ² / AREA} × (100π / 4) (1)
When the value of SF-1 is 100, the shape of the toner becomes a true sphere, and becomes larger as the value of SF-1 increases.
The shape factor SF-2 indicates the ratio of the unevenness of the toner shape, and is represented by the following formula (2). A value obtained by dividing the square of the perimeter PERI of the figure formed by projecting the toner onto the two-dimensional plane by the figure area AREA and multiplying by 100 / 4π.
SF-2 = {(PERI) ² / AREA} × (100 / 4π) (2)
When the value of SF-2 is 100, there is no unevenness on the toner surface, and as the value of SF-2 increases, the unevenness of the toner surface becomes more prominent.
Specifically, the shape factor is measured by taking a photograph of the toner with a scanning electron microscope (S-800: manufactured by Hitachi, Ltd.), introducing it into an image analyzer (LUSEX 3: manufactured by Nireco) and analyzing it. Calculated.

When the shape of the toner is close to a spherical shape, the contact state between the toner and the toner or the toner and the photoconductor becomes a point contact, so that the adsorbing force between the toners becomes weak and the fluidity increases, and the toner and the photoconductor The attraction force becomes weaker and the transfer rate becomes higher. If either of the shape factors SF-1 and SF-2 exceeds 180, the transfer rate is lowered and the cleaning property when attached to the transfer means is also lowered, which is not preferable.
The toner particle size is preferably in the range of 4 to 10 μm in terms of volume average particle size. When the particle size is smaller than this, it becomes a cause of background stains during development, fluidity is deteriorated, and further, it tends to agglomerate. On the other hand, when the particle size is larger than this, it is impossible to obtain a high-definition image due to toner scattering or resolution deterioration. In this embodiment, a toner having a volume average particle diameter of 6.5 μm is used.

Next, a modified example related to the main configuration of the present embodiment will be described.
FIG. 5 shows an image forming apparatus using a belt-like photoreceptor as an image carrier.
In the figure, the image forming apparatus uses a photosensitive belt 50A which is replaced with the intermediate transfer belt 5A shown in FIG.

  On one of the stretched surfaces of the photoreceptor belt 50A, a charging device 2 capable of forming an image for each color, a writing device (for the sake of convenience, writing light is indicated by L) and a developing device 3 are juxtaposed. The color image formed in each image forming section is superimposed by being transferred by the transfer roller 6 facing the image forming section on the inner side of the photoreceptor belt 50A, and then is recorded on the recording paper S by the secondary transfer roller. Are collectively transferred.

FIG. 6 is a diagram showing a modification of the main part of the configuration shown in FIG. 2, and the configuration shown in FIG. 6 is a configuration in which the cover 101 and the unit 31 swing independently. That is, as described in the configuration related to FIG. 2, the unit 31 is not forcedly urged, and is swung by its own weight through the user or the operator after the cover 101 is opened. It has become.
In this case, the configuration for the unit 31 is the same as the configuration shown in FIGS. As a result, the cost of parts can be reduced by the amount that does not require the clockwise urging structure provided to the unit 31.

FIG. 7 shows a configuration in which the cover 101 and the unit 31 shown in FIGS. 2 and 6 are integrated without being separated.
That is, in the configuration shown in FIG. 7, the cover 101 shown in FIG. 2 is replaced with the unit 31 (indicated by reference numeral 31 ′ for convenience). Also in this configuration, the same individuality as shown in FIG. 2 is used for the setting of the rotation direction of the rollers 16A and 16B constituting the registration roller 16 and the contact / separation mechanism. As a result, the number of parts can be reduced.

2 Photoreceptor as an example of an image carrier 7 Transfer roller 5A Intermediate transfer belt as another example of an image carrier 16 Registration roller 16A One roller 16B Roller facing one roller 31 Unit 101 Cover 101A Support point shaft 103 Pressure release Member θ Predetermined swing angle

Japanese Utility Model Publication 63-200844 Japanese Patent No. 3033996

Claims (7)

An image carrier and a pair of rollers facing each other across a conveyance path of a recording sheet to which an image from the image carrier is transferred, and the recording sheet is directed toward a transfer position of the image carried on the image carrier. A rocking member that supports a conveying member composed of a pair of rollers capable of nipping and conveying, and one roller of the pair of rollers equipped on the conveying member so as to be able to come into contact with and separate from another roller facing the roller. In the transfer device in which the movable unit is provided on the cover side that forms the openable / closable outline of the housing body,
The unit is provided in a state which swings by its own weight in conjunction with the said cover rotation axis of said one roller of the pair of rollers as a fulcrum is opened,
The rotational axis of the one roller of the pair of rollers, spaced from each other from the pair of said one roller and a state in which said one other roller is brought into contact with each other opposed thereto of the roller depending on the swing amount of the unit in the direction to swing by rotating said one roller of the pair of rollers in nip conveyance direction of the recording sheet, to which said one roller of the pair of rollers A one- way clutch that idles one of the rollers in response to the unit swinging in a direction in which the other roller facing each other approaches each other ;
The one of the pair of rollers is configured to record the recording when the one roller of the pair of rollers and the other roller facing the roller abut each other when the unit swings. A transfer device characterized in that a rotation amount capable of pulling out a leading end portion of a sheet from a corresponding contact position is set. The transfer apparatus according to claim 1, wherein
The one roller of the pair of rollers supported by the unit is imparted with a habit of being brought into contact with the other roller facing the roller, and the unit has a predetermined swing angle. A pressure release member is provided for releasing the contact behavior when the pressure reaches the value, and the pressure release member changes a distance between the opposing surfaces of the image carrier and the transfer member according to a swing angle of the unit. A transfer device using a cam having a cam profile. The transfer device according to claim 2.
Based on the cam profile, the pressure release member is opposed to one roller of the pair of rollers corresponding to the distance between the opposed axes of the rollers when the unit is swung, and the roller is opposed to the roller. A transfer device characterized in that the rollers are made larger than when the other rollers are in contact with each other. The transfer apparatus according to claim 2 or 3,
When the pressure release member reaches a predetermined swing angle of the unit, the distance between the opposing shafts of the one roller of the pair of rollers and the other roller facing the roller becomes the maximum. A transfer device characterized by having a configuration. The transfer apparatus according to claim 1, wherein
A transfer device, wherein a belt-like transfer member is used as the image carrier. The transfer apparatus according to claim 1, wherein
2. A transfer apparatus according to claim 1, wherein a belt-like photoconductor used in an image forming unit is used as the image carrier.   An image forming apparatus using the transfer device according to claim 1.

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