JPH07261582A - Image forming device - Google Patents

Abstract

PURPOSE:To allow high-brilliance printing without disturbing the toner image formed directly on the image receiving paper by providing the first fixing device for heating a thermoplastic resin or an additive of toner to the glass transition temperature or above and the second fixing device for heating it to the temperature higher than that of the first fixing device. CONSTITUTION:The first fixing device 25 is constituted of a noncontact type heating device heating by radiation heat in no contact such as an infrared lamp. When a thermoplastic resin mainly made of a toner or the wax constituent of an additive is heated to the glass transition temperature or above, the resin or wax constituent contained in the toner indicates stickiness on the toner surface, and the toners together and the toner and a carrier 20 are stuck by the wax. A heating roller fixing unit can be used for the second fixing device 26, it heats the toner on the carrier 20 fed through the first fixing device 25 to the outflow starting temperature or above of the thermoplastic resin which is the principal constituent of the toner, and a toner image is fixed on the carrier 20.

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 an aperture) 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 has the following features as compared with an electrophotographic image forming apparatus which has been widely used in the past.

In the electrophotographic system, a photoconductor is used. The photoconductor is uniformly charged, then an electrostatic latent image is formed, and the latent image is visualized with toner on powder. The toner image adhered on the photoconductor is transferred onto the image receiving paper, and the toner image is heat-fixed or pressure-fixed to form the desired image on the image receiving paper. In the image forming apparatus in which the toner flow is controlled by the method, the target toner image can be directly formed on the image receiving paper, so that the image forming process is simplified and it is advantageous to downsize the apparatus. . In particular, in this process, since the photoreceptor is not required, the durability of the device is improved, and it is advantageous from the ecological point of view that only the toner needs to be replenished.

Further, in the electrophotographic system, the latent image is completely transferred to the toner image in the process of developing the electrostatic latent image formed on the photoconductor with powder toner. Instead, the toner image on the photoconductor is not completely transferred onto the image receiving paper even in the process of transferring the visualized toner image onto the image receiving paper with some noise. So, some noise enters here as well,
Even in the process of fixing the toner image on the image receiving paper, since the fixing is usually performed by bringing the high temperature heat roller into contact with the toner image, the contact between the image receiving paper and the heat roller causes a slip before the fixing. The toner image is disturbed.

As described above, in the electrophotographic system, the image is gradually disturbed from the initial electrostatic latent image (the entropy of information increases) in the process of three times in total. In the image forming apparatus in which the toner flow is controlled by the opening as described above, the visible image (toner image) is directly formed on the image receiving paper, and the fixing process is the only factor that disturbs the image. Therefore, it is possible to form a higher definition image than the electrophotographic method.

This image forming apparatus comprises a flat plate made of an insulator, 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 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 adhered 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.

[0011]

However, even in the conventional image forming apparatus in which the toner flow is controlled by the opening as described above, the toner image initially formed is disturbed in the fixing process. For example, even if the arrangement of the openings is set to 600 DPI, the heat roller comes into contact with the toner image in the fixing process and disturbs the toner image.
There was a problem that only a considerable image could be formed. This becomes a big problem especially when full-colored.

That is, in the case of monochromatic black and white, even if the above problems occur, an aperture array equivalent to 600 DPI is formed in order to obtain an image equivalent to 200 DPI. When stacking, 1 pixel is 4
Since the dots are formed, in order to output the pixels at 200 DPI, it is necessary to form an aperture array having a resolution of 600 × 4 = 2400 DPI per color, which causes a problem of extremely high manufacturing cost. occured.

The present invention has been made to solve the above-mentioned problems, and provides an inexpensive image forming apparatus capable of high-definition printing without disturbing a toner image directly formed on an image receiving paper. The purpose is to do.

[0014]

In order to achieve this object, the image forming apparatus of the present invention comprises a toner flow control means for controlling the flow of charged toner to form a desired toner image on a support. An image forming apparatus comprising: a toner supply unit for supplying toner to the toner flow control unit, wherein the toner adhered on the support is a thermoplastic resin or a toner which is a main component of the toner. A first fixing device for heating to a temperature equal to or higher than the glass transition temperature of the wax component which is the additive for the toner, and at least the temperature of the first fixing device or higher with respect to the toner on the support passing through the first fixing device. And a second fixing device for heating at 1.

[0015]

According to the image forming apparatus of the present invention having the above-mentioned structure, in the first fixing device, at least heat of such a degree that toner particles in a powder state and easily displaced from each other due to an external force are weakly fused to each other. Since the heat above the glass transition temperature of the thermoplastic resin which is the main component of the toner or the wax component which is the additive is preferably given to the toner on the support,
Here, the toner is in a half-kneaded state, and subsequently, it is completely fixed on the support or the image receiving paper by the second fixing device, and the mutual positions of the adhered toner are not disturbed.
It is possible to form a high-definition image without causing printing defects such as thickening of characters and images and fogging on a white background.

[0016]

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 of the present invention. A cylindrical rear electrode having a 1 mm gap above an aperture electrode body 1 as toner flow control means. The back electrode roller 22 is rotatably arranged on a chassis (not shown), and is configured to be able to convey the support body 20 inserted into the gap. 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. 20 is the destination of the first fixing device 25.
Also, a second fixing device 26 is provided.

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 a toner carrying roller 14 as a toner carrying member and a toner layer regulating blade 18. Here, the toner carrying roller 14 carries the toner 16 and conveys it toward the aperture electrode body 1, and the supply roller 12 has the toner 16 with respect to the toner carrying roller 14.
To supply.

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 layer regulating blade 18
Is for adjusting the amount of the toner 16 carried on the toner carrying roller 14 to be uniform on the roller surface and for uniformly charging the toner 16, and is pressed against the toner carrying roller 14. .

As shown in FIG. 2, the aperture electrode body 1 includes a 25 μm thick insulating sheet 2 made of polyimide and having a diameter of 1 μm.
A plurality of apertures 6 of 00 μm are formed in one row, and a control electrode 4 having a thickness of 1 μm is formed on each upper surface of the apertures 6, and the aperture 6 and the control electrode 4 constitute a control unit. Then, the aperture electrode body 1 is
As shown in FIG. 1, in a state where the control electrode 4 is opposed to the support body 20 side, the insulating sheet 2 is pressed against the toner carrying roller 14 at the aperture position.

Here, the positional relationship between the aperture 6 of the aperture electrode body 1 and the toner carrying roller 14 will be described in detail. As shown in FIG. 3, each center line 30 of each aperture 6 has a toner carrying roller 14. It is arranged so as to pass through the uppermost portion of the peripheral surface of and the central shaft 32 of the toner carrying roller 14. According to this, each aperture 6
Based on the uppermost part of the peripheral surface of the toner carrying roller 14,
By arranging them evenly on the left and right, the distribution of the toner 16 passing through each aperture 6 can be made uniform over the entire area of the aperture. In addition, the wall surface of the aperture 6 and the toner 16
Since the flying direction of the toner is parallel to the flying direction of the toner, it is possible to stably fly the toner.

Further, the aperture electrode body 1 itself has an aperture 6 with respect to the toner carrying roller 14 as shown in FIG.
It is pressed so that it bends to the left and right about the same angle. As a result, the contact area between the aperture electrode body 1 and the toner carrying roller 14 can be increased, and the lower periphery of the aperture 6 can be pressed uniformly to the left and right, so that uneven toner concentration is minimized. Can be suppressed.

A control voltage application circuit 8 as a control voltage application means is connected between the control electrode 4 and the toner carrying roller 14. This control voltage applying circuit 8
A voltage of 0V or + 50V is applied to the control electrode 4 based on the image signal.

Further, a DC power source 24 is connected between the back electrode roller 22 and the toner carrying roller 14, and this DC power source is + with respect to the back electrode roller 22.
A voltage of 1 kV can be applied.

Next, the structure of the fixing unit, which is the main part of the present invention, will be described with reference to FIG.

The first fixing device 25 is composed of a non-contact type heating device such as an infrared lamp or a xenon flash lamp which heats by radiant heat in a non-contact manner. By heating above the glass transition temperature of the wax component, the resin or wax component contained in the toner exhibits tackiness on the toner surface, and the toner particles and the toner and the support 20 are attached by the wax.

As the second fixing device 26, a hot roll fixing device can be used, but a non-contact type heating device such as the above-mentioned infrared lamp or xenon flash lamp may be used. In the second fixing device 26, the toner on the support 20 that has passed through the first fixing device 25 is heated to a temperature equal to or higher than the outflow start temperature of the thermoplastic resin, which is the main component of the toner, and then the support 20 is heated. The toner image is fixed on.

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

First, by rotating the toner carrying roller 14 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 roller 14 to be negatively charged. The toner is carried on the toner carrying roller 14. Toner 1 carried
The layer 6 is thinned by the layer regulation blade 18 and charged, and then is conveyed toward the aperture electrode body 1 by the rotation of the toner carrying roller 14. Then, the toner on the toner carrying roller 14 is supplied to the bottom of the aperture 6 while being rubbed by the insulating sheet 2 of the aperture electrode body 1.

Here, in accordance with the image signal, the control electrode 4 corresponding to the image portion is fed from the control voltage applying circuit 8 to +.
A voltage of 50V is applied. As a result, a line of electric force directed from the control electrode 4 to the toner carrying roller 14 is formed in the vicinity of the aperture 6 corresponding to the image portion due to the potential difference between the control electrode 4 and the toner carrying roller 14. 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 to the control electrode 4 side. The extracted toner 16 further flies toward the support 20 due to the electric field formed between the support 20 and the aperture electrode body 1 by the voltage applied to the back electrode 22, and the toner 16 on the support 20 rises. To form pixels.

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 carrying roller 1
The toner 16 on 4 does not pass through the aperture 6 because it is not subjected to electrostatic force.

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.

Thereafter, the toner image formed on the support 20 is heated by the first fixing device 25 at a temperature lower than the fixing temperature, as described above, and the thermoplastic resin which is the main component of the toner or the toner. After the wax component, which is the additive of (1), becomes sticky, and thereby adhesive force is generated between the toner particles and between the toner and the support 20, the toner image is not disturbed even when contacted with a heat roll or the like. And a second fixing device 2 including a heat roll fixing device
It is fixed on the support 20 by 6.

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, so that 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 a mechanical force or the like by sliding with the aperture electrode body 1 and enters the aperture 6 corresponding to the non-image portion, the inside of 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 an inexpensive drive element can be provided. Can be used.

In addition, the insulating sheet 2 of the aperture electrode body 1
Is directed toward the toner carrying roller 14 side, so that the toner
Even if 6 is not present, the control electrode 4 and the toner carrying roller 14 do not come into contact with each other and electrically short-circuit, and the drive element is not destroyed.

Further, since the aperture electrode body 1 and the toner 16 on the toner carrying roller 14 are in contact with each other at the entrance portion of the aperture 6, the toner 16 accumulated at the entrance portion of the aperture 6 is not supported. Since the toner 16 is pushed away by the toner sequentially supplied, the toner 16 does not accumulate and bridge to block the aperture 6.

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, in the above embodiment, the control voltage of the aperture corresponding to the non-image portion is set to 0V, but 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.

Further, instead of the support in the above embodiment, an intermediate transfer film made of a resin film having a small specific heat capacity is used, and the toner image semi-fixed on the intermediate transfer film is fixed to the second fixing device. In this case, the image may be transferred while being fixed on the image receiving paper composed of plain paper. An image forming apparatus having such a structure is shown in FIG. Here, members having the same numbers as in FIG. 1 have the same operation.

In FIG. 4, a toner image is formed on the entire surface of the intermediate transfer film 27 as in the above embodiment.

Thereafter, the toner image formed on the intermediate transfer film 27 is heated by the first fixing device 25 at a temperature lower than the fixing temperature, as described above, or the thermoplastic resin which is the main component of the toner, or Adhesiveness is generated in the wax component, which is an additive of the toner, and an adhesive force is generated between the toners and between the toner and the surface of the intermediate transfer film 27 so that the toner image is not disturbed even when contacted with a heat roll or the like. After that, the 2nd consists of a heat roll fixing device
The intermediate transfer film 27 and the image receiving paper 21 are placed on the fixing device 26, and the toner image carrying surface of the intermediate transfer film 27 is placed on the image receiving paper 2.
The toner on the intermediate transfer film 27 semi-fixed by the first fixing device 25 is heated to the flow start temperature of the thermoplastic resin, which is the main component of the toner, by supplying the toners in the state of facing 1 to the first fixing device 25. The image is transferred onto the image receiving paper 21. After that, the toner image is fixed on the image receiving paper 21 by being cooled.

Further, in the above embodiment, the image forming apparatus forms a single color image using one kind of toner, but it may be configured to form a multicolor image using toners of a plurality of colors. Good.

FIG. 5 is a diagram showing an outline of the configuration of an image forming apparatus of such a modified example. Here, the same parts as those in FIG. Further, regarding the toner supply device 10, the control voltage application circuit 8, and the first fixing device 25 in the above-described embodiment, when a plurality of color toners are used, the same number as the number of toner colors is required, and in FIG. Since the color toners are used, the numbers A, B, and C are added to the end of each member number.

In FIG. 5, toner supply devices 10A, 1
The toners (not shown) of yellow, magenta, and cyan colors, which are supplied by 0B and 10C and are controlled by the control voltage application circuits 8A, 8B, and 8C to form an image on the support 20, have different components. Therefore, naturally, the thermal characteristics such as the glass transition temperature and the flow starting temperature are different. Therefore, the first fixing devices 25A, 25B, and 2
5C are also set to different temperatures, and their operations are controlled by the control unit 40.

As described above, when a plurality of color toners are used, each time a toner image of one color is formed, semi-fixing is performed by the first fixing device, and then a toner image of the next color is formed. , The toner image of each color is not disturbed while the toner image of the next color is formed, and therefore a high-resolution color image can be formed with an inexpensive device.

Although three colors of toner are used in FIG. 5, four or more colors or two or less colors may be used.

[0050]

As is apparent from the above description, in the image forming apparatus of the present invention, in the first fixing device, at least toner particles which are in a powder state and are easily displaced from each other due to an external force are weakly fused. Since the heat of adhering, preferably the heat above the glass transition temperature of the thermoplastic resin which is the main component of the toner or the wax component which is an additive, is applied to the toner on the support, the toner here is in a half-kneaded state. become,
Subsequently, when the toner is completely fixed on the support or the image receiving paper by the second fixing device, the mutual positions of the adhered toners are not disturbed, and printing defects such as thickening of characters and images and fog on a white background do not occur. A high-definition image can be formed.

[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.

FIG. 4 is a diagram showing another embodiment of the present invention.

FIG. 5 is a diagram showing another embodiment 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 14 Toner carrying roller 20 Support 22 Back electrode roller 24 DC power supply 25 First fixing device 26 Second fixing device 27 Intermediate transfer film

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location G03G 9/087 9/08 15/05 15/01 K 114 A 15/08 502 Z G03G 9/08 365 15/00 115

Claims (3)

[Claims] 1. A toner flow control means for controlling a flow of charged toner to form a desired toner image on a support, and a toner supply means for supplying toner to the toner flow control means. An image forming apparatus comprising: a first toner for heating the toner adhered on the support to a temperature not lower than a glass transition temperature of a thermoplastic resin which is a main component of the toner or a wax component which is an additive of the toner. An image forming apparatus comprising: a fixing device; and a second fixing device for heating the toner on the support that has passed through the first fixing device at least at a temperature higher than that of the first fixing device. . 2. The support is an intermediate transfer film made of a material having a small heat capacity, and the toner image is transferred from the intermediate transfer film onto the image receiving paper in the second fixing device. The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus. 3. The first fixing device comprises a non-contact type heating device.
The image forming apparatus according to item 1.