JPH07290755A - Image forming apparatus - Google Patents

Abstract

PURPOSE:To provide an image forming apparatus capable of always supplying a constant amt. of toner of constant charge quantity, reducing the irregularity or fluctuations of image density and capable of obtaining an image having necessary density and contrast or necessary printing speed. CONSTITUTION:A toner feed device 10 is constituted of a toner support film 13, a film supply roll 15 supplying a toner support film and a film taking-up roll 17 taking up the supplied toner support film. The toner support film 13 supports toner 16 and is fed toward an aperture electrode 1. A toner support belt 13 having toner not subjected to printing supported thereon is taken up by the film taking-up roll 17. Therefore, toner of constant charge quantity having no history can be always supplied to the aperture electrode 1 in constant thickness at the time of printing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus which can be used in copying machines, printers, plotters, facsimiles and the like.

[0002]

2. Description of the Related Art Conventionally, as one of image forming apparatuses, an electrode having a plurality of openings (hereinafter referred to as apertures) is used, and a voltage is applied to the electrode based on image data. U.S. Pat. No. 3,689,935 discloses controlling toner particles so that they can pass through the aperture and forming an image on a support by the toner particles that have passed.

This image forming apparatus comprises a flat plate made of an insulating material, a continuous reference electrode formed on one surface of the flat plate, and a plurality of control electrodes insulated from each other formed on the other surface. , An aperture electrode body having at least one row of apertures formed through each of the control electrodes, and a means for selectively applying a potential between the reference electrode and the control electrode. Positioning the support in the particle flow path by relatively moving the toner supplying means for supplying the charged toner particles so that the flow of the toner particles passing through the aperture is modulated by the potential and the support and the aperture electrode body And means for doing so.

Also, for example, US Pat. No. 4,743,926.
Nos. 4,755,837, 4,780,733, and 4,847,796 disclose an image forming apparatus in which an aperture electrode body is arranged with a control electrode on the support side and a reference electrode on the toner supply side. There is.

In contrast, US Pat. No. 4,912,489
In the specification of the above U.S. Pat. It is described that it can be suppressed to about 1/4 as compared with the image forming apparatus.

Here, the "off" means a time when the toner particles are not attached to the support, that is, a time when a blank portion of an image is formed, and conversely, "on" means that the support is on the support. It means a time point when a toner image is formed on.

In the conventional image forming apparatus as described above, the toner supplying means is a flat surface having a smooth surface or an appropriate roughness, or a brush shape, and is conveyed to the vicinity of the opening. A toner carrier for temporarily carrying the charged toner on the way is provided, and the toner charged by an appropriate toner charging means is carried on the toner carrier, and the toner is opened by a mechanical or electromagnetic force. The one that is configured to supply the vicinity of the part was generally used.

For example, the present applicant uses a toner carrying member for carrying toner to an aperture and a toner supplying member for supplying toner to the toner carrying member, and a toner layer carried on the surface of the toner carrying member. An image forming apparatus configured to supply toner by bringing the toner into close proximity or in contact / pressure contact with the aperture electrode body is disclosed in, for example, the specification and drawings attached to the application of Japanese Patent Application No. 4-254494. In this image forming apparatus, only a control electrode is provided on an insulating flat plate having an opening, and at least the surface of the toner carrying member is made conductive so that this surface is grounded to 0 V (volt) and grounded to the control electrode. An electric field formed between the toner carrier member surface, that is, an electric field directly applied to both ends of the toner layer causes ON / OFF of the toner flight.
It is configured to control OFF.

Here, the portion where the control electrode is formed may be on the surface of the insulating flat plate facing the support or on the surface facing the toner carrying member. Particularly in the latter case, the distance from the control electrode to the surface of the toner carrying member can be minimized, so that printing drive can be performed with a smaller control electrode applied voltage.

[0010]

However, in the conventional image forming apparatus as described above, when the printing operation is continued, the toner remaining on the surface of the toner carrying member without being printed is printed. Is adhered and fixed, and is a factor that causes fluctuations in the supply amount and charge amount of the toner that is subsequently carried. Due to fluctuations in the toner supply amount and charge amount,
There are problems that the image density is gradually reduced, and that the density of the output image is different immediately after the high-density solid is output and after the white background for a certain time.

The present invention has been made in order to solve the above-mentioned problems, and it is possible to always supply a constant amount of toner with a constant charge amount, and to reduce variations and fluctuations in image density.
An object of the present invention is to provide an image forming apparatus capable of obtaining an image having a required density and contrast and a printing speed.

[0012]

In order to achieve this object, an image forming apparatus of the present invention comprises a toner flow control means for controlling the flow of charged toner, and a toner flow control means arranged to face the toner flow control means. At least a surface of the toner bearing film facing the toner flow control means has a conductive or semi-conductive property, a film feeding means for feeding the toner carrying film, and a toner carrying film fed from the film feeding means. And a toner supply means for supplying the toner to the toner carrying film supplied from the film supply means.

Further, in this case, the toner carrying film and the toner flow control means may be arranged to be in pressure contact with each other via the toner.

[0014]

In the image forming apparatus of the present invention having the above-mentioned structure, the toner carrying film on which the toner is once carried by the toner supplying means is conveyed to the position of the toner flow control means to supply the toner for printing. The toner carrying film carrying the toner which was not carried is conveyed as it is,
It is wound up by the film winding means. Therefore, at the time of printing, toner having a constant thickness and charge amount with no history is always supplied to the toner flow control means, and residual toner not used for printing is used for the next printing. Does not affect the amount of charge or the amount of charge.

[0015]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing an outline of the image forming apparatus of the present invention.

In FIG. 1, a cylindrical back electrode roller 22 as a back electrode is provided on the upper side of the aperture electrode body 1 as a toner flow control means with a gap of about 1 mm, and is a chassis (not shown). It is rotatably disposed in the space and is configured to be able to convey the support body 20 inserted into the gap. Further, below the aperture electrode body 1,
A toner conveying device 10 is arranged along the longitudinal direction of the aperture electrode body 1, and a fixing device 26 is arranged at the destination of the support body 20 conveyed by the back electrode roller 22. Has been done. Further, all movable members, voltage application circuits, power supplies, detection means, and the like described later are controlled by the control unit 40.

The toner carrying device 10 has a toner case 11 which also serves as a housing for the entire toner carrying device 10.
And the toner 16 stored in the toner case 11.
A supply roller 12 as a toner supply means, a toner carrying film 13, a carrying film supporting roller 14,
A film supply roll 15 as a film supply means,
It is composed of a film take-up roll 17 as a film take-up means, a toner layer regulation blade 18 as a toner layer regulation means, which is attached to the inner wall of the toner case 11, a nip roller 19 and a tension roller 21.

Here, the toner carrying film 1
3 is a member for carrying the toner 16 and conveying it toward the aperture electrode body 1, and a conductive material such as metal, which is connected to the ground, on at least one surface of a plastic film substrate such as PET or polyimide. Alternatively, it is composed of a laminated film-like member having a thin film layer formed of a semiconductive material, or a metal film-like member having appropriate strength and rigidity such as stainless steel, and in any case, at least one surface Must be a conductive surface (or semi-conductive).

The toner-bearing film 13 before use is wound around a film holding roll 15, which is sequentially drawn out from the film holding roll 15 each time a printing operation progresses, and then nip roller 19 and tension roller 2 are used.
1, the carrier film supporting roller 14 is conveyed while being wound while being tensioned. On the conductive surface portion of the toner carrying film 13, the supply roller 1
The toner 16 is supplied by 2 and is used for printing at the position of the aperture 6. After that, the toner carrying film 13 carrying the toner which has not been used for printing is taken up by the film take-up roll 17. The tension roller 21 is made of a conductive material such as metal and is grounded. Therefore, the conductive surface portion of the toner carrying film 13 is grounded via the tension roller 21.

When the toner carrying film 13 is made of a metal film member, the carrying film supporting roller 14 is made of a conductive material such as grounded metal so that the toner carrying film 13 is grounded. You may do it.

The supply roller 12 supplies the toner 16 to the toner carrying film 13, and at the same time, rubs the toner 16 at the contact portion between the supply roller 12 and the toner carrying film 13. It is a member for charging.

The supply roller 12 and the carrier film supporting roller 14 are rotatably supported by the toner case 11 in the direction of the arrow shown in the figure, and both of them have the toner carrier film 13 wound around the carrier film supporting roller 14 as described above. They are arranged in parallel so as to be in contact with the supply roller 12 while pressing it with a constant pressure.

On the surface where the toner carrying film 13 and the carrying film supporting roller 14 are in contact with each other, the toner carrying film 1 is rotated by the rotation of the carrying film supporting roller 14.
3 has a constant frictional resistance so that 3 is pulled out from the film take-up roll 15, and the carrier film support roller is connected to the carrier member drive motor 36, and the supply roller 1
2 is also connected to a supply roller drive motor 37, and a film winding roll 17 for winding the used toner carrying film 13 is also a winding roll drive motor 38.
The respective rollers and the carrier film 13 are driven in the directions of the arrows in FIG. 1 by the respective motors based on the signal from the control unit 40.

Then, by the movement of the toner carrying film 13 and the supply roller 12 in the direction of the arrow shown in FIG. 1, the toner 16 sent from the supply roller 12 is rubbed against the toner carrying film 13 and negatively charged. The toner image is carried on the toner carrying film 13 by an adhesion force such as a mirror image force and a van der Waals force induced on the surface of the toner carrying film 13 by the charge.

The toner layer regulating blade 18 is for adjusting the amount of the toner 16 carried on the toner carrying film 13 so as to be uniform, and is in the toner case 11 in FIG. The toner layer regulating blade 18 is arranged on the upstream side of the position of the aperture 6 with respect to the moving direction of the film 13, that is, the supply direction of the toner 16, and the toner layer regulating blade 18 is pressed against the toner carrying film 13 with a uniform pressure. Is installed. The toner layer regulating blade 18 selects an appropriate material and coating so as to uniformly charge the toner 16 carried on the toner carrying film 13, and connects a power source (AC / DC and superposition thereof). You may perform the structure like this.

As shown in FIG. 2, the aperture electrode body 1 includes a polyimide insulating sheet 2 having a thickness of 12.5 to 75 μm, a circular shape having a diameter of 40 to 100 μm, or an elliptical or rectangular cross section having an area equivalent thereto. A plurality of apertures 6 are formed in one row, and the toner carrying film 13
A control electrode 4 having a thickness of 1 to 15 μm is formed for each aperture 6 on the surface opposite to, and the control unit is configured by the aperture 6 and the control electrode 4.

In the aperture electrode body 1, with the control electrode 4 facing the support body 20 side, as shown in FIG. 3, at the aperture position of the insulating sheet 2, the toner 16 and the toner carrying film 13 are interposed. Being pressed against.

The positional relationship between the apertures 6 of the aperture electrode body 1 and the carrier film supporting roller 14 will be described in detail. As shown in FIG. 3, each center line 30 of each aperture 6 supports the carrier film. The uppermost part of the peripheral surface of the roller 14 and the central axis 3 of the carrier film supporting roller 14
It is arranged so as to pass through 2 and. According to this
The respective apertures 6 are evenly arranged on the left and right with respect to the uppermost portion of the peripheral surface of the carrier film supporting roller 14, so that the distribution of the toner 16 passing through each aperture 6 is made uniform throughout the aperture. You can Further, since the wall surface of the aperture 6 and the flying direction of the toner 16 are parallel to each other, it is possible to stably fly the toner.

Further, as shown in FIG. 3, the aperture electrode body 1 itself is pressed against the carrier film support roller 14 so as to bend left and right about the aperture 6 by the same angle. As a result, the contact area between the aperture electrode body 1 and the toner carrying film 13 can be increased, and the lower peripheral portion of the aperture 6 can be pressed evenly to the left and right, so that uneven toner concentration is minimized. Can be suppressed.

The control electrode 4 and the toner carrying film 13
A control voltage applying circuit 8 as a control voltage applying means is connected between the control surface and the conductive surface. The control voltage applying circuit 8 applies 0 V to the control electrode 4 based on the image signal,
Alternatively, it is configured to apply a voltage of + 50V.

Further, a DC power source 24 is provided between the back electrode roller 22 and the conductive surface of the toner carrying film 13.
Is connected to the back electrode roller 22 in accordance with a signal from the control unit 40.
A voltage of kV can be applied.

Next, the operation of the image forming apparatus configured as described above will be described.

First, by the movement of the toner carrying film 13 and the supply roller 12 in the direction of the arrow shown in FIG. 1, the toner 16 sent from the supply roller 12 is rubbed against the toner carrying film 13 and negatively charged. Then, the toner is carried on the toner carrying film 13. The carried toner 16 is thinned by the layer regulating blade 18 and then conveyed toward the aperture electrode body 1 by the movement of the toner carrying film 13. Then, the toner on the toner-carrying film 13 is rubbed by the insulating sheet 2 of the aperture electrode body 1 and supplied below the aperture 6.

Here, in accordance with the image signal, the control voltage applying circuit 8 adds + to the control electrode 4 corresponding to the image portion.
A voltage of 50V is applied. As a result, due to the potential difference between the control electrode 4 and the toner carrying film 13, an electric force line from the control electrode 4 toward the toner carrying film 13 is formed near the aperture 6 corresponding to the image portion. As a result, the negatively charged toner receives an electrostatic force in the direction of higher electric potential, passes through the aperture 6 from the toner carrying film 13, and is drawn to the control electrode 4 side. The extracted toner 16 further flies toward the support body 20 due to the electric field formed between the support body 20 and the aperture electrode body 1 by the voltage applied to the back electrode 22.
Pixels are formed by depositing on the support 20.

A voltage of 0V is applied from the control voltage applying circuit 8 to the control electrode 4 corresponding to the non-image portion.
As a result, since no electric field is formed between the toner carrying film 13 and the control electrode 4, the toner 16 on the toner carrying film 13 does not receive the electrostatic force and therefore does not pass through the aperture 6.

Further, the support 20 is fed by one pixel in the direction perpendicular to the aperture row while the toner 16 forms one row of pixels on the surface thereof. Then, the toner image is formed on the entire surface of the support 20 by repeating the above process. Then, the formed toner image is fixed on the support 20 by the fixing device 26.

In the above process, since the aperture electrode body 1 and the toner 16 on the toner-carrying film 13 are in contact with each other at the entrance portion of the aperture 6, the toner 16 deposited at the entrance portion of the aperture 6 is a toner. Since the toner 16 is washed away by the toner sequentially supplied by the carrier film 13, the toner 16 does not accumulate and bridge to block the aperture 6.

Further, since the control electric field by the control electrode 4 is formed between the control electrode 4 and the toner carrying surface of the toner carrying film 13, the aperture electrode body 1 having the above-mentioned structure is formed.
In the case of using, the gap forming the electric field is only the thickness of the layer of the carried toner 16, and the control electric field can be directly applied to the toner 16 existing in this narrow gap.
Since control efficiency is high and a desired control electric field can be obtained with a small control voltage, a drive element such as an IC provided in the control voltage application circuit 8 for applying a voltage to the control electrode 4 should be inexpensive and low in breakdown voltage. Can be used.

As described above, the amount of toner 16 supplied from the supply roller 12 remains on the surface of the toner-carrying film 13 used for printing in the portion corresponding to the white background, and a dark black background is output. Even in the portion where the toner is carried, the toner 16 on the toner carrying film 13 is entirely supported by the support 20.
The toner does not fly upward, and the toner having a small particle size and a large charge amount per unit volume remains on the toner carrying film 13 due to the image force.

As described above, the surface of the toner carrying film 13 affected by the history of the immediately preceding output result is as it is in FIG.
In the direction of the arrow, the film is taken up by the film take-up roll 17 and a layer of the toner 16 newly carried on the toner carrying film 13 is always clean with respect to the aperture 6 in the printing operation immediately below the aperture 6. As a result, the problem that the carry amount / charge amount of the toner carried by the output result history changes as described above does not occur, and the carry amount / charge amount is always constant. The toner 16 can be supplied to the aperture 6.

Here, the toner 16 remaining on the toner carrying film 13 is pressed or heated by the nip roller 19 to press the toner 16 or heat the toner carrying film 1.
It may be fixed on the surface 3.

The present invention is not limited to the embodiments described in detail above, and various modifications can be made without departing from the spirit of the invention.

For example, although the control voltage of the aperture corresponding to the non-image portion is set to 0V in the above embodiment, it may be a negative voltage. In this case, an image with less fogging can be obtained.

In the above embodiment, the flexible substrate-shaped aperture electrode body is used as the toner flow control means. For example, a knitted electrode body as described in the specification of US Pat. No. 5,036,341 is used. It is also possible to use.

A suitable insulating spacer may be attached to the surface of the toner carrying member. As a result, it is possible to more reliably prevent a short circuit between the toner carrying member and the control electrode, and at the same time, to periodically peel off the toner adhering to the toner flow control means to assist the circulation of the toner in the toner supply means. .

Although the polarity of the toner is negative in the above embodiment, it may be positive by appropriately selecting the material of the other members.

Further, in the above-mentioned embodiment, the surface of the toner carrying member is made of a grounded conductive material.
This conductive material may be connected to a power source that provides an appropriate bias potential. In this case, the voltage applied to the control electrode is
It changes according to this bias potential.

[0049]

As is apparent from the above description, in the image forming apparatus of the present invention, the toner carrying film on which the toner is once carried by the toner supply means is conveyed to the position of the toner flow control means to remove the toner. The toner-carrying film that carries the toner that has been supplied and used for printing is conveyed as it is and wound up on the film take-up roll.
At the time of printing, since the toner having a constant thickness and charge amount without history is always supplied to the toner flow control means, the residual toner not used for the printing may be used for the next printing. In addition, the amount of the toner layer and the amount of charge are not affected.

Therefore, it is possible to provide an image forming apparatus which can always supply a constant amount of toner with a constant amount of charge, have little variation or fluctuation in image density, and can obtain an image having a desired density and contrast and a printing speed. You can

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment embodying the configuration of an image forming apparatus of the present invention.

FIG. 2 is a perspective view showing a configuration of an aperture electrode body used in the image forming apparatus of the present invention.

FIG. 3 is a diagram schematically showing a configuration of an aperture electrode body and a toner carrying roller used in the image forming apparatus of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Aperture electrode body 2 Insulating sheet 4 Control electrode 6 Aperture 8 Control voltage application circuit 10 Toner supply device 12 Supply roller 13 Toner carrying film 14 Toner carrying roller 15 Film holding roll 17 Film take-up roll 18 Toner layer regulating blade 19 Nip roller 22 Rear electrode roller 24 DC power supply 40 Control unit

Continuation of front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display location G03G 15/08 504 A

Claims (4)

[Claims] 1. A toner flow control means for controlling the flow of charged toner, and a toner flow control means arranged to face the toner flow control means. At least a surface facing the toner flow control means has a conductive or semi-conductive characteristic. A toner carrying film having, a film supplying means for supplying the toner carrying film, a film winding means for winding the toner carrying film supplied from the film supplying means, and a film supplying means supplied from the film supplying means. An image forming apparatus comprising: a toner supply unit for supplying toner to a toner carrying film. 2. The toner supply means is arranged upstream of a portion of the toner carrying film facing the toner flow control means in the toner carrying film supply direction. Image forming device. 3. The image forming apparatus according to claim 2, wherein a toner layer restriction unit is arranged on the toner carrying film between the toner supply unit and the toner flow control unit. 4. The image forming apparatus according to claim 1, wherein the toner carrying film and the toner flow control means are arranged so as to be in pressure contact with each other via the toner.