JPH02284181A - Tandem type electrostatic carrier/transfer device - Google Patents

Abstract

PURPOSE:To prevent color slurring in multiple transfer by making the rotation and drive of first and second rollers synchronized by timing belts. CONSTITUTION:The driving force transmitting means (timing belts) 58 and 60 synchronize the rotation and drive of the first and second rollers 24 and 26 out of plural rollers between which a suction belt 20 stretches, the first and second rollers 24 and 26 being positioned upstream and downstream, respectively, in a paper carrying path; therefore, change in a rotating speed ratio of the first roller 24 to the second roller 26 can be prevented. Since photosensitive bodies 36, 40, and 44 are arranged on the paper carrying path and between the first and second rollers 24 and 26, transfer can be performed without the occurrence of dislocation. Thus, color slurring does not occur in multiple transfer.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an electrostatic transport transfer device used in an image forming apparatus such as an electrophotographic copying machine.

Conventional technology For example, in an image forming apparatus such as an electrophotographic copying machine that applies the principle of xerography, an image carrier (
The photoreceptor is represented below. ) is exposed to light to form an electrostatic latent image, this electrostatic latent image is developed with charged toner to form a toner image, and the toner image is further transferred to a transfer material (hereinafter referred to as paper) and fixed to make a copy. I am getting things. Among these series of steps, full-color copying becomes possible by performing latent image formation, development, and transfer for each color component on the same sheet of paper. Electrostatic transfer transfer devices are used in full-color copying machines and other devices that require multiple transfers as described above, to synchronize the paper with the photoreceptor and transfer it to a predetermined transfer position at a predetermined timing. be done.

An electrostatic transfer transfer device uses a corotron or the like to generate an electric discharge on the back side of an adsorption belt made of a dielectric belt, a mesh belt, etc., electrostatically attracts the paper to the front side of the adsorption belt, conveys the paper, and transfers the paper to the transfer position. Applying an electric field between the above-mentioned discharge-based transfer and a plurality of electrodes formed on the back side of an adsorption belt made of a semiconductive resin film,
There is a known method in which paper is electrostatically attracted to the surface side of an adsorption belt, conveyed, and transferred at a transfer position.

Hereinafter, problems and the like will be specifically explained in a static N transport transfer device configured using an adsorption belt made of a semiconductive resin film.

FIG. 14 is a diagram showing an example of a conventional electrostatic transfer transfer device. As shown in FIG. 15, a semiconductive resin film 4 having a plurality of electrodes 2 arranged side by side at regular intervals on one side is supported on a rigid drum (not shown) to form a transfer drum 6.
is brought into contact with a photoreceptor 8 having the same diameter as this at a transfer position, and a transfer power supply means 10 is provided for supplying a voltage of opposite polarity to the toner polarity to the electrode 2 that has been moved to the transfer position among the electrodes 2, A power supply means 12 for attracting paper is provided for alternately supplying a high voltage (for example, positive potential) and a low voltage (for example, ground potential) to the electrode 2 that has been moved to the paper transport position among the electrodes 2. Since latent image formation and development are performed for each color component each time the photoreceptor 8 rotates once, the sheet of paper attracted onto the transfer drum 6 in the direction of arrow A is treated as the same original every time it passes through the transfer position. Transfer of toner images of different colors is made for the image. Then, the paper onto which the toner images of three to four colors have been multi-transferred is discharged in the direction of arrow B by, for example, releasing the paper suction power supply means 12.

In this type of drum-type electrostatic transfer transfer device, it is necessary to perform latent image formation, development, and transfer multiple times for each color component, so it takes a long time to obtain one copy. It has the disadvantage of being slow.

To overcome these drawbacks, there is a tandem electrostatic transfer transfer device as shown in FIG. In this conventional example, the resin film 4 is formed into an endless belt-like adsorption belt, which is mounted on at least two rollers 14 and 16, and a plurality of photoreceptors are formed on which latent images are formed and developed for each color component. 8 is brought into contact with the resin film 4 at its flat part, and the transfer power supply means 10 and the paper adsorption power supply means 12 are provided in correspondence with the arrangement of the resin film 4 and the photoreceptor 8. I try to do just that many times.

The paper that is moved in the direction of arrow A and attracted to the flat part of the resin film 4 is transferred multiple toner images of each color from each photoreceptor that operates in synchronization with the movement of the paper, and then transferred to the roller 1 on the exit side.
Due to the curvature of 6, it is ejected in the B direction. In this way, since a plurality of photoreceptors are provided for each color component, the copying speed is improved compared to the case where a single photoreceptor is used.

Problems to be Solved by the Invention However, in the conventional tandem type electrostatic transfer transfer device, the part that attracts and holds the paper is formed in the shape of a belt, so due to the flexible nature of the belt, If expansion and contraction occurs, and the rotational speeds of the rollers 14 and 16 shown in FIG. 16, for example, vary relative to each other, a positional shift will occur in the transferred images from each photoreceptor, resulting in a problem of color misregistration in multiple transferred images. there were.

Therefore, a first object of the present invention is to provide a tandem electrostatic transport transfer device that is free from the possibility of color misregistration in multiple transferred images.

On the other hand, when looking at the transfer position where the photoreceptor and the resin film come into contact, it is known that the contact force has a close relationship with the transfer quality. In other words, if the contact force is too high, hollow characters (a phenomenon of hollow images) tend to occur, and
If the contact force is too low, the transfer efficiency will decrease. Therefore, it is necessary to set the contact force between the photoreceptor and the resin film within an appropriate range.

Therefore, a second object of the present invention is to stabilize the contact force between the photoreceptor and the resin film, thereby contributing to improving the transfer quality.

Means to solve problems The above-mentioned technical problem is shown below (1).

This problem is solved by means (2).

(1) A suction belt that moves while electrostatically adsorbing the paper to which the toner image of the photoreceptor is transferred to the outer surface at least at the transfer position; and at least two sheets on which the suction belt is mounted.
the two rollers and the suction belt that has moved to the transfer position.
In a tandem electrostatic transfer transfer device comprising a transfer unit that performs transfer by supplying an electric charge having a polarity opposite to that of the toner, a first roller located upstream of the paper transfer path among the rollers; The second roller located on the downstream side of the paper conveyance path is driven to rotate in synchronization with the driving force transmission means.

(2) In the means of (,1) above, the circumferential speed of the portion of the first roller on which the suction belt is mounted is lower than the circumferential speed of the portion of the second roller on which the suction belt is mounted. .

According to the means of operation (1), among the rollers on which the suction belt is mounted, the first roller located on the upstream side of the paper conveyance path and the second roller located on the same downstream side are synchronized by the driving force transmission means. Since the first roller and the second roller are rotationally driven, fluctuations in the rotational speed ratio of the first roller and the second roller are prevented. and,
Since the photoreceptor is placed on the paper conveyance path, that is, between the first roller and the second roller, transfer can be performed without positional deviation, and there is no color deviation in multiple transferred images. The fear that arises will disappear.

According to the means (2), since the circumferential speed of the portion of the first roller on which the suction belt is mounted is made smaller than the circumferential speed of the portion of the second roller on which the suction belt is mounted, the first roller and second
When the rollers are rotated synchronously by the driving force transmission means, the suction belt slips on the first roller or the second roller, and the dynamic friction force applies a moderate tension to the suction belt between the first and second rollers. As a result, the contact force between the photoreceptor and the suction belt can be stabilized, and the transfer quality can be improved.

Example Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a side view of a tandem electrostatic transfer transfer device showing an embodiment of the means (1). 20 is a resin film belt as an adsorption belt formed by forming a semi-conductive resin film on an endless belt, and a plurality of electrodes 2 are arranged at regular intervals on the inside thereof.
2 are installed in parallel.

The resin film belt 20 includes a first roller 24 and a second roller 26.
, a driven roller 28 and a tension roller 30. A biasing member 34 is provided between the tension roller 30 and the frame 32, which biases itself in the direction in which it extends, so that an appropriate tension can be applied to the resin film belt 20 in the moving direction. It has become.

A cyan photoreceptor 36, which is developed with cyan toner, is in contact with the outside of the first roller 24 side of the resin film belt 20 mounted between the first roller 24 and the second roller 26. On the downstream side in the rotational direction of the photoconductor of the contact position (transfer position), there is a peeling claw 38 for cyan color that peels off the paper on which the toner image has been transferred so as not to wrap it around the photoconductor and returns it onto the resin film belt 20. It is in contact with the photoreceptor 36 so as to be able to move toward and away from it. Similarly, a magenta photoreceptor 40, a yellow emergency photoreceptor 44, and peeling claws 44 and 46 are provided on the downstream side of the cyan photoreceptor 36 in the paper conveyance direction. 48
is a brush power supply device provided inside the resin film belt 20 in this embodiment to supply power to the electrodes 22 of the resin film belt, and this brush power supply device 48 is connected to the first roller 2.
A conveyance unit 481 for conveying the paper fed near 4 to the turning position by the cyan photoconductor 36, transporting the paper from the transfer position by the cyan photoconductor 36 to the transfer position by the magenta photoconductor 40. a transport unit 482 for transporting;
and a conveyance section 483 for conveying the paper from the transfer position by the magenta photoconductor 40 to the transfer position for the yellow photoconductor 44, and transfer sections 484, 485, and 486 for performing transfer at each transfer position. ing.

In this embodiment, in order to rotate the first roller 24 and the second roller 26 synchronously, a grooved pulley 50.5 having the same effective diameter is used.
2 are fixed to the first roller 24 and the second roller 26, respectively, and a timing belt 58 is installed between the grooved pulley 56 and the grooved pulley 50 of a drive source 54 such as a motor, thereby forming the grooved boob IJ-56.

A timing belt 60 is installed between the resin film belt 2 and the grooved boolean 56 is rotated clockwise in the figure to transmit power through the timing belt.
0 in the same direction. As shown in FIG. 12, a plurality of protrusions 58a are formed at regular intervals on the inside of the timing belt 58, and the first roller 50
Since grooves 50a are formed on the outer periphery of the timing belt 58 at the same intervals as the intervals between the protrusions 58a, the timing belt 58 and the first roller 50 are engaged with each other, and the first roller 24 can be rotationally driven without slipping. Since the configurations of the grooved pulleys 52 and 56 and the timing belt 60 are the same,
No slip occurs in each power transmission portion, and therefore the first roller 24 and the second roller 26 can be rotated synchronously at the same rotational speed.

In this embodiment, since the outer diameters of the first roller 24 and the second roller 26 are the same, their circumferential speeds are also the same.

In the brush power supply device 48, the conveyance section and the transfer section each have a common configuration, so only a specific configuration example of the conveyance section 481 and the transfer section 484 will be described.

In the conveyance section 481, as shown in FIG. 3, a suction brush 62 connected to the high voltage side and a suction brush 64 connected to the low voltage side slide onto the electrode 22 from inside the resin film belt 20. They are arranged alternately. here,
High voltage and low voltage mean relatively + (plus) side voltage and relatively - (minus) side voltage. Therefore, specific combinations of high voltage and low voltage include +2000V, +500V, and +1500V.
and OV, +1000V and -500V, OV and -1500
V, -500V, -2000V, etc. In this embodiment, a positive voltage is supplied to the suction brush 62 from a suction power source 68 via a switch 66, and the suction brush 64 is grounded.

According to this configuration, by turning on the switch 66, an electric field can be generated between the electrode group that the suction brush 62 contacts and the electrode group that the suction brush 64 contacts. 20 and can be transported.

As shown in FIG. 4, the transfer unit 484 of the brush power supply device includes a transfer brush 70 that slides on the electrode 22 that has moved to the transfer position, and a transfer brush 70 that is provided immediately upstream of the transfer brush 70 in the paper conveyance direction. It consists of an auxiliary brush 76 and a stripping brush 76 provided on the downstream side. The transfer brush 70 can be supplied with a positive voltage from a transfer power source 74 via a switch 72, and the auxiliary transfer brush 76 and the peeling brush 76' are grounded.

The reason why a positive voltage is supplied to the transfer brush 70 is that in this embodiment, the image area on the photoreceptor is exposed and developed with toner of negative polarity. Further, the purpose of providing the auxiliary transfer brush 76 is to stabilize the electric field at the transfer position and obtain good transfer quality. That is, since transfer is generally performed by the charged toner particles on the photoreceptor moving along the lines of electric force that form the transfer electric field, by providing an auxiliary transfer brush, the transfer electric field is confined in a narrow space. This prevents gap transfer, where toner particles are transferred before they move to the transfer position, and causes defects such as blurring of the transferred image.

The resin film belt 20 is made of acrylic, vinyl chloride, polyester,
It is formed by adding an appropriate amount of an antistatic agent such as carbon black to a resin such as polypropylene or various rubbers so that its volume resistivity is 10 6 to 10 12 Ω·cm. The electrode 22 is formed on the resin film belt 20 by a conventional conductive pattern forming technique such as etching or screen printing, and has a width of about 0.5 mm. Regarding the spacing between each electrode, if the spacing is more than one color mark, electrode patterns (a phenomenon in which the transferred image has areas of high density and areas of low density depending on the pitch of the electrodes) are likely to occur, so the smaller the spacing, the better. If it is too small, secondary failures such as short circuits will occur, so set it to about 0.
．． 5 mm is optimal.

In the above configuration, when the paper 82 is fed from the paper cassette 78 by the paper feed roller 80, the leading edge of the paper is detected by a paper feed sensor (not shown), and an image is written on the photoreceptors 36, 40, 44 by this detection. The timing is determined. At the same time, a predetermined DC voltage is applied to each conveyance section and transfer section of the brush power supply device 48. Transport section 481
The paper attracted by the photoreceptor 36 is conveyed directly below the photoreceptor 36, and the cyan toner image is transferred by the transfer unit 484. The sheet of paper peeled off by the peeling brush 76' is conveyed directly below the photoreceptor 40 by the suction force of the conveyance section 482, and the magenta toner image is transferred by the transfer section 485. The paper is peeled off from the surface of the photoreceptor 40 by a peeling brush, and conveyed directly below the photoreceptor 44 by the suction force of the conveyance section 483. And here the transfer section 486
The yellow toner image is transferred to the paper. The writing of images onto the photoreceptors 36, 40, and 44 is performed sequentially with a delay corresponding to the paper withdrawal time, and is controlled so that each of the three colors overlaps. The paper on which multiple transfer has been completed is further sent to a fixing device (not shown), where fixing is performed. In this embodiment, multiple transfer of three colors is performed, but black may be added to these to perform multiple transfer of four colors.

According to this embodiment, the first roller 24 and the second roller 26
can be rotated almost completely synchronously, the load on the resin film belt 20 is reduced, and its smooth rotation becomes possible. Moreover, by synchronously rotating the first roller 24 and the second roller 26, there is no possibility that the resin film 20 located in the paper conveyance section will expand or contract. Therefore, toner images from each photoreceptor can be accurately transferred to desired positions on the paper, and color shift due to multiple transfers is prevented.

If the resin film belt needs to be reinforced, it may be done as shown in FIGS. 5 and 6, for example. A Cu electrode 8 is formed by etching on a support 84 made of an insulator such as polyester.
6a, and a Ni electrode 86b is formed on the surface of the Cu electrode 86a for the purpose of preventing oxidation and improving wear resistance to form the electrode 86. The support 84 and the electrode 86 are formed so that the vicinity of the end of the electrode 86 is exposed. It is coated with a resin film 88.

If such a resin film belt is used to supply power from the outside to the exposed portion of the electrode 86, the same operation as in the above embodiment can be achieved. Furthermore, since expansion and contraction of the resin film can be prevented, color shift can be further improved.

FIG. 7 and FIG. 8 are diagrams for explaining an embodiment of the means (2). In the embodiment shown in FIG. 7, the diameters of the portions of the first roller 24 and the second roller 26 on which the resin film is mounted are both Dl, and the grooved boot on the first roller 24 side is Dl. l
-50 and the effective diameter of the grooved pulley 56 on the drive source side are both d, and the effective diameter of the grooved pulley 52 on the second roller 26 side is d2, which is smaller than dl.

By doing this, the rotational speed of the first roller 24 is
As d2/d(ku1) of the rotational speed of the second roller 26,
The circumferential speed of the first roller 24 can be made smaller than the circumferential speed of the second roller 26.

In the embodiment shown in FIG. 8, the grooved pulley 50.52
．． The effective diameters of both rollers 56 are set to dl, and the outer diameter of the first roller 24° is set to 2, which is smaller than the outer diameter of the second roller 26. According to this configuration, since the rotational speeds of the first roller 24' and the second roller 26° are the same, the first roller 24' and the second roller 26' have the same rotational speed.
The circumferential speed of the second roller 26 is smaller than the circumferential speed of the second roller 26 due to the smaller outer diameter.

By making the circumferential speed of the first roller smaller than the circumferential speed of the second roller in this way, it is possible to apply a constant tension between the first roller and the second roller. The contact force can be easily set within a certain range, making it possible to prevent hollow characters or transfer defects from occurring.

In the previous embodiments, a timing belt was used as the driving force transmitting means, but a chain, a gear, or the like may be used as the driving force transmitting means in order to periodically rotate the first and second rollers.

In the embodiments described above, the power supply brushes, for example, the suction brushes 62 and 64, are arranged in one row or alternately in two rows, but as shown in FIG.
It may be arranged over the entire surface of the second forming surface. By doing this, the frequency of sliding of the electrode against the brush when the device is used for the same period of time is reduced, and the life span is improved.

The power supply brush 62 may be fixedly supported, but as shown in FIG. Then apply the suction brush 6 with appropriate pressure.
2 may be pressed against the electrode forming surface EL. According to this configuration, a substantially constant contact force can always be obtained even if the brush is worn out.

Electricity may be supplied to the electrodes of the resin film belt not only by a conductive brush but also by a conductive roll as shown in FIG. In place of the suction brush 62 in FIG. 3, conductive rolls 94 and 96 slightly displaced are brought into contact with the electrode forming surface EL, and in place of the suction brush 64, conductive rolls 94 and 96, also slightly displaced, are brought into contact with the electrode forming surface EL. roll 98,100
is brought into contact with the electrode forming surface EL. According to this configuration, since the conductive roll rotates as the electrode moves, there are no sliding parts, and the life of the power feeding section is improved. Here, the conductive rolls are used with their positions shifted.
This is to supply voltage to a desired range of electrode groups.

If a single conductive roll is required for the same potential portion, for example, as shown in FIG.
02 may be slightly inclined with respect to the direction in which the electrodes 22 of the resin film belt are formed and brought into contact with the entire surface. This results in
The conductive roll 102 and the plurality of electrodes 22 can be easily brought into contact.

In addition to the conductive brush and the conductive roll, components of the power supply section shown in FIG. 13, for example, can be used. A permanent magnet 106 is placed inside the conductive housing 104, and its magnetic force causes the ferromagnetic metal fluid 10 to
8 is supported and brought into contact with the electrode forming surface EL.

As the ferromagnetic metal fluid 108, for example, one in which fine iron particles are dispersed in mercury can be used. According to this configuration, there is no fear that the electrodes will be worn out, and a large amount of current can flow.

In the description of the embodiment, the suction belt is a resin film belt, but the present invention is not limited to this configuration, and is also effective when the suction belt is a dielectric belt or a mesh belt.

Effects of the Invention As detailed above, in the tandem electrostatic transfer transfer device of the present invention, since the first roller and the second roller are rotationally driven in synchronization by the timing belt, color misregistration is prevented in multiple transferred images. This has the effect of eliminating the fear that this may occur.

Further, by setting the circumferential speed of the first roller to be smaller than the circumferential speed of the second roller, it is possible to stabilize the contact force between the photoreceptor and the resin film and improve the transfer quality.

[Brief explanation of drawings]

Fig. 1 is a side view of a tandem electrostatic transfer transfer device showing an embodiment of the present invention, Fig. 2 is an enlarged view of the vicinity of the first roller, and Fig. 3 is a side view of the specific structure of the pumping section of the brush power feeding device. 4 is an explanatory diagram of the specific configuration of the transfer section of the brush power feeding device, FIG. 5 is a plan view showing a modified example of the resin film belt, and FIG. 6 is a diagram taken along the line ■-■ in FIG. 7 and 8 are diagrams for explaining an embodiment of the means of (2). Figures 9 to 13 are diagrams for explaining modified examples of the embodiment. 16 are diagrams for explaining the prior art. 0.88...resin film, 2.86...electrode, 4...first roller, 26...second roller, 6 ．．
40.44... Photoreceptor, 8... Brush power supply device, 8.60... Timing belt. Applicant: Fuji Xerox Co., Ltd. Agent: Patent Attorney Takashi Matsumoto

Claims (4)

[Claims] (1) A suction belt that moves while electrostatically adsorbing the paper to which the toner image of the photoreceptor is transferred to the outer surface at least at the transfer position; and at least two sheets on which the suction belt is mounted.
the two rollers and the suction belt that has moved to the transfer position.
In a tandem electrostatic transfer transfer device comprising a transfer unit that performs transfer by supplying an electric charge with a polarity opposite to that of the toner, a first roller located on the upstream side of the paper transfer path among the rollers; A tandem electrostatic transfer transfer device characterized in that a second roller located on the downstream side of a paper transfer path is rotationally driven in synchronization with a driving force transmission means. (2) The circumferential speed of the portion of the first roller on which the suction belt is mounted is made smaller than the circumferential speed of the portion of the second roller on which the suction belt is mounted. Tandem type electrostatic transfer transfer device. (3) The diameters of the portions of the first and second rollers on which the adsorption belt is mounted are made to match, and the diameter of the portion of the first roller on which the driving force transmission means is mounted is set to the diameter of the portion on which the driving force transmission means of the second roller is mounted. 3. The tandem electrostatic transfer transfer device according to claim 1, wherein the diameter of the portion on which the transmission means is mounted is larger than the diameter of the portion on which the transmission means is mounted. (4) The diameters of the portions of the first and second rollers on which the driving force transmission means are mounted are made to match, and the diameters of the portions of the first roller on which the suction belt is mounted are made to match the diameters of the portions on which the driving force transmission means of the first and second rollers are mounted.
3. The tandem electrostatic transfer transfer device according to claim 1, wherein the diameter of the roller is smaller than the diameter of the portion on which the suction belt is mounted.