JPH07117268A - Image forming apparatus - Google Patents

Abstract

PURPOSE:To provide an image forming apparatus in which control of an aperture electrode is facilitated, necessary image density, contrast and printing speed can be obtained and a toner supply efficiency is high. CONSTITUTION:An image forming apparatus comprises an aperture electrode 1 for controlling a flow of charged toner, a toner carrier roller 14 for carrying toner and supplying the toner to the electrode 1, and further a sliding wire so disposed as to slide together upon rotation of the roller 14 at a position near apertures 6 at an upstream side of a toner supplying direction to the apertures 6. Toner 16 adhered to the roller 14 can be flown on a support by a small drive voltage.

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. A means for supplying the charged toner particles so that the flow of the toner particles passing through the aperture is modulated by the electric potential, and a means for relatively moving the support and the aperture electrode body to position the support in the particle flow path. It consists of and.

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

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.

[0007]

However, in the conventional image forming apparatus as described above, since a strong electrostatic attraction is generated between the surface of the toner carrier and the charged toner, the toner supply efficiency is increased. In order to obtain the required image density, contrast and printing speed, it is necessary to increase the voltage for driving the aperture electrode body and the driving potential difference between ON / OFF of the toner flow, and therefore the pressure resistance is high and the cost is high. Therefore, the cost of the entire device has increased.

Further, the toner having a high charge amount is adhered to the surface of the toner carrier, which is the closest to the surface of the toner carrier, by a strong image force, and the toner layer outside the lowermost toner layer has a low driving voltage. Therefore, about half of the toner supplied to the opening was not used for printing, and the toner supply efficiency was low.

The present invention has been made to solve the above-mentioned problems, and the control of the toner flow control means is easy, the required image density, contrast, and printing speed can be obtained, and the toner is supplied. An object is to provide an image forming apparatus with high efficiency.

[0010]

In order to achieve this object, an image forming apparatus of the present invention has a toner flow control means having a control section for controlling the flow of charged toner, and carries the toner. A toner carrier that supplies the toner to the toner flow control means, and is arranged in the vicinity of the control unit so as to contact the surface of the toner carrier near the toner source in the toner supply direction. And a carrier sliding member.

[0011]

In the image forming apparatus of the present invention having the above structure, the toner firmly attached to the surface of the toner carrier is
It is possible to slightly separate the surface of the toner carrier from the surface of the toner carrier by a mechanical force by the carrier sliding member located near the control unit and upstream of the toner supply direction. Therefore, the force (image force + van der Waals force) for confining all the toner on the toner carrier to the toner carrier can be dramatically reduced in the vicinity of the control unit, and thus the toner flow control can be performed. ON / O voltage for driving means and toner flow
The drive potential difference of the FF can be reduced.

[0012]

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

FIG. 1 is a diagram showing an outline of an image forming apparatus embodying the present invention. A cylindrical rear surface having a gap of 1 mm on the upper side of an aperture electrode body 1 as a toner flow control means. An electrode roller 22 is rotatably arranged on a chassis (not shown), and the support body 20 is inserted into the gap.
Are configured to be transported. Further, a toner supply device 10 is arranged below the aperture electrode body 1 along the longitudinal direction of the aperture electrode body 1, and further, a support body conveyed by the back electrode roller 22. A fixing device 26 is disposed at the destination of the movement of 20.

Next, the respective components will be described in detail. In the toner supply device 10, the toner case 11 also serving as a housing of the entire device, the toner 16 housed in the toner case 11, and the supply roller 12 are provided. And Toner
The toner carrier roller 14 as a carrier, the toner layer regulating blade 18, and the sliding wire 36 are included. Here, the toner carrying roller 14 carries the toner 16 and conveys it toward the aperture electrode body 1, and the supply roller 12 is the toner carrying roller 1.
The toner 16 is supplied to the No. 4 toner.

The supply roller 12 and the toner carrying roller 14 are rotatably supported by the toner case 11 in the direction of the arrow shown in FIG. Further, the toner carrying roller 14 is connected to a motor (not shown), the supply roller 12 is also connected to a motor (not shown), and each roller is driven by the motor.

The toner carrying roller 14 and the supply roller 1
The toner 16 that has been slid between 2 and is charged is carried on the surface of the toner carrying roller 14 by the mirror image force generated between the charged charge and the surface of the toner carrying roller 14 and the Van der Waals force. Are transported.

The toner layer regulating blade 18 is for adjusting the amount of the toner 16 carried on the toner carrying roller 14 so that it is uniform on the roller surface, and is pressed against the toner carrying roller 14.

The sliding wire 36 is a wire made of tungsten, and is upstream of the aperture electrode body 1 in the toner supply direction (the arrow direction showing the rotation direction of the toner carrying roller 14 in FIG. 1) and the aperture. At a position close to the aperture 6 of the electrode body 1, the toner carrying roller 14
It is arranged so as to be parallel to the axis line of
It is pressed against the outer peripheral surface of the toner carrying roller 14,
As a result, the toner carrying roller 14 is configured to slide on the outer peripheral surface of the toner carrying roller 14 as the toner carrying roller 14 rotates. The sliding wire 36 is connected to a power source 38, and a voltage having the same polarity as the charging polarity of the toner 16 is applied.

Power source 3 connected to the sliding wire 36
8, the control voltage application circuit 8, and the DC power supply 24 are controlled by a print control unit 40 including a well-known CPU and the like.

As shown in FIG. 2, the aperture electrode body 1 includes a polyimide insulating sheet 2 having a thickness of 25 to 100 μm, and a plurality of apertures 6 having a diameter of 30 to 100 μm arranged in a line or. The control electrodes 4 formed in a plurality of rows and having a thickness of 1 to 10 μm are formed on the upper surface of each aperture 6.
It is formed for each. As shown in FIG. 1, the aperture electrode body 1 has the toner layer 16 on the toner carrying roller 14 at the aperture 6 position of the insulating sheet 2 with the control electrode 4 facing the support body 20 side. Are in contact through.

A control voltage applying circuit 8 is connected between the control electrode 4 and the toner carrying roller 14.
The control voltage application circuit 8 is configured to apply 0V or a predetermined positive voltage to the control electrode 4 based on the image signal.

Further, a DC power supply 24 is connected between the back electrode roller 22 and the toner carrying roller 14, and this DC power supply can apply a voltage of +1 kV to the back electrode roller 22. It is like this.

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

First, as the toner carrying roller 14 and the supply roller 12 rotate 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 roller 14 and becomes negative. It is charged on the toner carrying roller 14 and carried on the toner carrying roller 14. The carried toner 16 is thinned by the layer regulation blade 18 and then conveyed toward the aperture electrode body 1 by the rotation of the toner carrying roller 14.

At this time, the thinned toner 16 is carried by the strong image force generated between the toner 16 and the toner carrying roller 14, and it is quite strong to peel it off by the force of the electric field. An electric field is needed.

However, in this embodiment, the toner 16 firmly adhered to the toner carrying roller 14 is stripped by the sliding wire 36 by a mechanical force. For toner that is even far from the roller surface, the image force is inversely proportional to the square of the distance. Therefore, the toner is supplied immediately below the aperture 6 with almost no restraint force on the roller surface, and a slight amount. Toner flow ON / OFF with control voltage
It becomes possible to control.

At this time, since the sliding wire 36 is located upstream of the aperture 6 in the toner supply direction, the aperture 6 is not clogged by the toner 16 held by the sliding wire 36.

The sliding wire 36 can be applied with an arbitrary voltage by a power source 38 connected thereto. For example, if the same polarity as the toner charging polarity, that is, a negative potential is applied to the sliding wire 36, the adhesion of the toner 16 to the sliding wire 36 is suppressed, and the front side of the sliding wire 36 ( The toner 16 does not accumulate on the upstream side with respect to the toner supply direction.

Further, by applying a negative high voltage (for example, -500V) to the sliding wire 36 and using a conductive or low resistance toner as the toner 16, charge injection can be performed here, so that the toner The charge amount of 16 becomes stable.

Here, in accordance with the image signal, the control voltage applying circuit 8 applies to the control electrode 4 corresponding to the image portion.
A control voltage when printing is turned on, which is controlled by the printing control unit 40, is applied. As a result, the control electrode 4 and the toner carrying roller 1 are provided near the aperture 6 corresponding to the image portion.
An electric force line from the control electrode 4 toward the toner carrying roller 14 is formed by the potential difference between the four. 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 roller 14, and is drawn out to the control electrode 4 side. Toner 1 pulled out
Further, 6 is caused to fly toward the support body 20 by an electric field formed between the support body 20 and the aperture electrode body 1 by the voltage applied to the back electrode 22, and is deposited on the support body 20. Pixels are formed.

A voltage of 0V is applied from the control voltage application 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 roller 14 and the control electrode 4, the toner 16 on the toner carrying roller 14 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.

If an insulating toner is used in the image forming apparatus constructed as described above, the toner carrying roller 14 is used.
The insulation between the control electrode 4 and the control electrode 4 is maintained, and the aperture 6 does not cause dielectric breakdown.

In the above process, the control electric field generated by the control electrode 4 is formed between the control electrode 4 and the inside of the aperture 6, and between the aperture 6 and the toner carrying surface of the toner carrying roller 14 which faces the aperture 6, and therefore the carrying is carried. Toner 1
Since the control electric field can be directly applied to 6, the control efficiency is good.

Further, even if a part of the supplied toner 16 receives mechanical force due to sliding with the aperture electrode body 1 and enters the aperture 6 corresponding to the non-image portion, inside the aperture 6 Since it can be controlled so as not to pass through the aperture 6 by the electric field, the toner controllability is good.

Further, since the toner carrying roller 14 and the aperture electrode body 1 are opposed to each other with the toner layer interposed therebetween, they can be arranged at a relatively short distance, so that the control voltage can be lowered and the driving element is inexpensive. Can be used.

In addition, the insulating sheet 2 of the aperture electrode body 1
Is directed to the toner carrying roller 14 side, so that even if the toner 16 does not exist on the toner carrying roller 14 due to a defect in the toner supply system, the control electrode 4 and the toner carrying roller 14 come into contact with each other and electrically short-circuit. However, the drive element is not destroyed.

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, this may be a negative voltage. In this case, an image with less fogging can be obtained. Further, in the above embodiment, the aperture electrode body is used as the toner flow control means, but it is also possible to use, for example, a knitted electrode body as described in the specification of US Pat. No. 5,036,341.

[0040]

As is apparent from the above description, according to the image forming apparatus of the present invention, the toner flow control means can be easily controlled and the required image density, contrast and printing speed can be obtained. Moreover, it is possible to provide an image forming apparatus having high toner supply efficiency.

[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.

[Explanation of symbols]

 1 Aperture Electrode Body 2 Insulating Sheet 4 Control Electrode 6 Aperture 14 Toner Carrier Roller 22 Back Electrode Roller 24 DC Power Supply 36 Sliding Wire

Claims (2)

[Claims] 1. A toner flow control unit having a control unit for controlling the flow of charged toner, a toner carrier for carrying the toner, and supplying the toner to the toner flow control unit. An image forming apparatus, comprising: a carrier sliding member disposed near the control unit and closer to the toner source in the toner supply direction so as to contact the surface of the toner carrier. 2. The toner carrier is composed of a roller, and the carrier sliding member is composed of a sliding wire arranged in contact with the toner carrier roller. The image forming apparatus according to claim 1, wherein: