JPS5836336B2 - Toner Zoutenshiya Sochi - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for electrically transferring an electrostatic toner image on an intermediate support surface onto a final support in the form of a sheet, and in particular to an electrostatic toner image on a relatively small diameter electrostatic drum. The present invention relates to an apparatus for electrically transferring an electrical toner image onto a final support in the form of a substantially planar sheet.

To explain the principle of electrostatic photography, first, an electrostatic latent image of the original image to be reproduced is formed on a photoconductive plate, and this electrostatic latent image is charged with a polarity opposite to that of the latent image. powder toner particles are deposited to develop this electrostatic latent image into a visible image.

When these powder toner particles come very close to the latent image, they are captured by the electric field of the electrostatic latent image and held in the same outline as the electrostatic latent image, so the latent image becomes a visible image. be.

Traditionally, a sheet of flat copy paper or other similar insulating support material has been superimposed on a toner image bearing plate image to electrically transfer the charged toner particles on the plate onto the copy paper.

Normally, when the copy sheet is in contact with the electrostatic plate surface, a corona discharge of opposite polarity to the charged toner is generated on the back side of the copy sheet to transfer the toner image.

Deposition of sufficient corona onto the sheet creates an electrostatic field between the copy paper and the grounded electrostatic plate, which causes toner particles to be electrically transferred from the electrostatic plate onto the copy sheet.

In order to faithfully transfer the toner image on the electrostatic plate to the copy sheet, the transfer must be completely or almost completely free of irregularities in the toner image.

It is therefore extremely important to ensure that the final support does not become electrically charged prior to contacting the final support with the electrostatic plate.

If the prematurely charged support sheet is moved towards the electrostatic plate, the toner particles on the electrostatic plate will be separated from the electrostatic plate before the support sheet comes into contact with the electrostatic plate.

Toner particles in the air away from the electrostatic plate are
Like electric charges, they have the property of repelling each other, so the size of the toner image finally formed on the support material tends to expand.

Therefore, the toner image ultimately transferred to the copy sheet is magnified, resulting in the generally undesirable no-low effect.

To prevent this type of image degradation, most automatic electrostatographic copiers require an appropriate positioning of the corona generator relative to the point of contact between the copy sheet and the electrostatic plate. A sufficient corona flow is applied to the copy sheet after the plates make contact.

However, in this case it must be ensured that the width of the contact area is relatively wider than the width of the corona flow, and the mounting position of the corona generator must be determined accurately.

Particularly in the case of small copying machines that use electrostatic drums with a relatively small diameter, the width of the transfer area, that is, the contact area, is narrower than the width of the corona flow because a corona generating device of conventional known technology is used. There is.

Therefore, under such conditions, the corona flow spreads beyond the boundaries of the contact area, resulting in premature charging of the support material.

It is therefore an object of the present invention to improve an apparatus for electrically transferring an electrostatic toner image on an electrostatic plate surface onto a final support sheet.

Another object of the present invention is to provide an electroimage transfer device for use in miniature copiers in which the size of the image transfer area is relatively limited.

Another object of the invention is to prevent premature charging of a copy sheet as it enters an electrostatic transfer station.

Still another object of the present invention is to copy. The size of the contact area between the sheet and the electrostatic plate supporting the toner image is smaller than the size of the corona flow used to make the transfer effective. be.

The above and other objects of the present invention provide a copy sheet feeder for stacking a sheet of final support material onto a moving electrostatic plate and a nip where the sheet of final support material contacts the electrostatic plate. It is installed near the surface of the static plate near the area, and the corona discharge current can be copied, sealed,
a corona generator that electrically transfers the toner image on the electrostatic plate surface onto the copy sheet surface; and a corona generator that extends into the corona stream and contacts the toner image-bearing electrostatic plate. Before that, the corona style was copied. This can be achieved by an image transfer system consisting of a corona generator and a grounded baffle body having a dielectric coating surface mounted between the corona generator and the static solder plate surface so as not to reach the sheet.

To better understand other objects and features of the present invention,
The present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 will be explained.

A relatively small diameter image recording drum 11 suitable for an automatic electrostatographic reproduction machine is rotated about a horizontal support shaft 12 in the direction shown and passed through a series of electrostatographic processing stations.

The drum consists of a grounded substrate 13 whose surface is coated with a photoconductive layer 14, such as selenium.

The photoconductive surface is first conventionally charged to a positive potential value and then exposed to a light image of the original to be reproduced, which records the image of the original as an electrostatic latent image on the photosensitive surface.

Next, as this electrostatic latent image passes through an electrostatographic development station 15, toner particles having the opposite polarity to the latent image, that is, negatively charged, are deposited on the latent image, thereby converting the electrostatic latent image into a visible image. Become.

The toner image bearing drum surface is then passed through a toner image transfer station 10 where the 1.toner image on the drum surface is transferred to a sheet of final support material in a manner described in detail below.

To explain the transfer operation, a sheet-shaped final support material 11 cut into a predetermined size is sent to a transfer station in synchronization with a toner image containing only developer on the surface of an electrostatic drum.

In order to carry out this sheet feeding, a pair of excitation forward rolls 2
A sheet feeding mechanism 19 consisting of 0 and 21 is provided.

In practice, this sheet-like support material is separated from a laminate sheet supply (not shown) and brought into suitable register with the moving drum surface before entering the two-way area between the rolls of the feed mechanism 19. Keep it.

After this, the sheet is engaged in the double area between the rolls and moves at the same speed as the drum toward the transfer station.

On the exit side of the advance roll assembly, a guide plate 24 is provided.
A plate is provided which allows the sheet to be moved precisely in the direction of the image transfer station.

This transfer station is provided with a pair of corona generators 30 and 31 parallel to each other as shown in FIG.

In terms of the rotation direction of the drum, the first corona generator 30 is
A transfer corona generator operative to electrically transfer toner particles on the drum surface onto the copy sheet surface, with one second corona generator 31 operative to attract the copy sheet to the drum surface during transfer. A sheet stripping corona generator operates to reduce or neutralize the electrostatic forces generated by the photoreceptor, thereby facilitating stripping of the sheet from the photoreceptor.

Next, the transfer corona generator 30 will be explained in detail.
The discharge device consists of a U-shaped conductive shield 31 extending longitudinally along the entire photoconductive drum surface.

The open end of the grounded U-shield 32 faces the drum surface near the dip area where the copy sheet advances and contacts the photoreceptor. A generating wire 33 is attached to which a high voltage applied causes a corona flow of positive charge to be emitted from the opening in the shield to the back side of the copy sheet.

A ground shield 32 provides electrical control of the corona discharge device and focuses the corona flow for uniform flow to the copy sheet.

The gap between the shield and the wire and the size of the opening in the shield are particularly related to the voltage of the power supply supplying the high voltage to the wire.

In the corona generator described in U.S. Pat. No. 2,836,725, invented by Vyverberg, approximately 800
A voltage of 0 volts was applied, and the width of the opening in the shield needed to be approximately 1.27 cIrL for optimal use.

If the opening of this shield were made narrower, the voltage of the corona generator would have to be significantly increased.

However, in reality, most copying machines are in a situation where it is not possible to increase the power supply voltage any further due to electrical risks.

In the case of a copying machine with a small diameter electrostatic drum as mentioned above,
Since the nip area between the electrostatic drum and the flat copy sheet is naturally narrow, the width of the corona flow that produces the transfer is considerably wider compared to this nip area.

This creates the potential for corona flow to extend beyond the boundaries of the nip area, resulting in undesirable premature charging of the copy sheet.

The apparatus according to the invention has a copy sheet tW'! A control baffle 40 is provided which allows the copy sheet to be physically and electrically shielded until it makes sufficient contact with the plate surface.

In this embodiment, the buffle is a guide device that orients the copy sheet and brings it into contact with the electrostatic plate surface before the copy sheet is exposed to the corona stream emanating from the corona generator 30.

This Batsuful 40 is placed close to the static drum, so
The final support material in the form of a sheet entering the toner image transfer station by means of a feed roll member is guided toward the tangential surface of the rotating photosensitive plate, comes into contact with the photosensitive surface, and then enters the corona stream.

As shown in FIG. 1, this buttful consists of an elongated body 41 whose one end is pivotally connected to a pivot pin 42, an extension arm 43 that projects horizontally between the corona generator and the photosensitive surface, and a boss portion 46. The position is adjusted using an adjustment pin 45 on which is placed.

When placing this buttful 40 on this adjustment pin 45, the extension arm 43 is located within the corona flow emitted from the corona generator 30, and physically unwraps the electrostatic plate portion from the corona flow. This prevents the copy sheet from becoming electrostatically charged in the front.

In particular, extending the tip of the arm to a part of the ion discharge port of the corona generator 30 limits the width of the ion discharge port of the corona generator and prevents ions from being discharged to the upstream side of the generator. It's for a reason.

As best seen in FIG. 2, the top surface of the buffle 40 is provided with an upwardly projecting surface 48 which engages the bottom surface of a copy sheet entering the transfer station.

This protruding surface 48 allows the copy sheet passing above to be
The arm 43 contacts the photoconductive plate in an area shielded from the ion current due to the corona discharge, such that the copy sheet contacts the photoconductive plate before being exposed to the ion stream due to the corona discharge. is achieved.

Note that the portion of the sheet that has contacted the photoconductive plate in front of the transfer area is advanced to the transfer area while remaining in contact with the plate.

This is because the strength of the copy sheet's beam or hips maintains that contact.

This baffle consists of a conductive metal substrate coated with a thin layer of dielectric material 50, and since the dielectric material is coated with a sufficiently thin layer, the static charge generated by the transfer corona generator is transferred into this substrate. I am drawn to it.

Since this substrate is grounded, it can act as a control device for the corona generator and limit the amount of charge that is deposited on the dielectric coating.

At the start of corona discharge, a predetermined amount of corona corresponding to the thickness of the dielectric coating is charged on this buffle, but after that, no more charge is charged due to the electrostatic field generated by this charged corona.

The device according to the invention has a diameter of about 8 mm. When used in an automatic electrostatic copying machine containing a 4 cm electrostatic drum, copying and
The width of the dip area between the sheet and the photoconductive surface is approximately 0.0 mm, depending on the thickness of the copy sheet. 3 mm to 0,41ILm
It changed to

A corona generator similar to that of U.S. Pat. No. 2,836,725 was provided near the nip area to electrically transfer the toner image on the electrostatic plate onto the copy sheet surface in a conventional manner.

The electrostatic plate was first charged to a positive potential of about 800 volts, and upon exposure, the value of the first potential in the background region was reduced to about 300 volts.

This electrostatic latent image is developed with negatively charged toner particles and is transferred from a single wire corona generator of 3 mil tungsten wire approximately 0.62 mm from the photosensitive surface to an electrostatic plate. A current of approximately 40 μA was applied to the toner image to transfer the toner image.

This corona generator is approximately 1.27 mm opposite the double area.
A bathoflu, similar to those previously described herein, was placed in a grounded shield with an aperture of n, extending approximately 2 mm from the electrostatic drum surface and into the corona flow to shield the corona flow.

This Batsuful has an electrostatic material of about 0. 7 mm to 1.
Manufactured with a conductive metal substrate spray-painted to a thickness of 5 mm, it acts as a physical and electrical barrier to corona flow, preventing premature charging of the copy sheet and ensuring that the reproduced image is not distorted. .

In this example, the buckle base was kept at ground potential, but
Some bias voltage other than ground potential may be applied to this substrate within the spirit of the invention.

The magnitude of the initial surge current flowing from the corona generator to this baffle can be minimized by applying a bias voltage to this substrate that is between ground potential and the potential of the corona generator wire and is applied to this buckle. The insulation requirements of the applied paint can be significantly lowered.

However, it is clear that this bias voltage alone is insufficient to prevent premature transfer of the toner image from occurring on the electrostatic plate surface.

Although the present invention has been described above based on one embodiment, the present invention is not limited to this embodiment, and various design changes can be made within the scope of the appended claims.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an image transfer device according to the present invention used in an automatic electrostatic copying machine using a drum-shaped replaceable photoreceptor having a relatively small diameter. Figure 2 shows the copy. FIG. 3 is a partially enlarged view of a baffle used to prevent early charging of the sheet. 17 - Sheet-like final support material, 30, 31 - Corona generator, 40 - Buttful body.

Claims (1)

[Scope of Claims] 1. A photoconductive plate, a sheet feeding device for contacting an image receiving sheet with the photoconductive plate, and a corona generator disposed to extend across the photoconductive plate in a transfer area. , wherein the ion emitting port of the corona generator faces the photoconductive plate, further comprising a baffle whose interior is made of a conductive material and whose surface is coated with a thin layer of a dielectric material; The baffle has an arm and a protrusion, the arm being located between the photoconductive plate and the corona generator and having a width across the plate, the distal end of the arm being located between the photoconductive plate and the corona generator. extending between the photoconductive plate and the ion emitting port of the corona generator in the sheet feeding direction, and surrounding a portion of the ion emitting port, and the protruding surface of the buttful being located at the rear end of the arm. and protrudes from the arm surface toward the photoconductive plate, and engages a surface of the image receiving sheet opposite to the surface to which the image is transferred so as to be formed on the protruding surface before being exposed to the ion stream from the corona generator. A transfer device characterized in that it comes into contact with a light guiding plate, which is an image receiving sheet that is becoming increasingly popular.