JPS61226766A - Method and device for image formation - Google Patents

Abstract

PURPOSE:To obtain recording images of invariably high picture quality by forming a toner image on an image formation body while separating the image formation body and a transfer means from each other, and then forming a new toner image on said toner image, and transferring those toner images to a transfer material at a time after the image forming body and transfer means contacts each other. CONSTITUTION:A transfer roller 50 is brought into contact with the image formation body 1 through the operation of an eccentric cam 54, etc., after a toner image which is one color before a multi-color toner image is completed passes through a transfer position and right before the multicolor toner image is transferred, and rotates by being driven by the image formation body 1. Therefore, the transfer roller 50 neither damages a toner image nor is stained with toner, and the contamination of the reverse surface of the transfer material is evaded. Further, the transfer material which is fed while timed to transfer operation is entered into a transfer area smoothly by the transfer roller 50 which is already driven to rotate. Consequently, recording images of high picture quality are obtained with good transfer efficiency without the contamination of the back surface of the transfer material nor image shifting.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention relates to an image forming method for forming a multicolor toner image on an image forming member and transferring it to a transfer material to obtain a recorded image, and an image forming method thereof. It relates to devices and is used, for example, in fields such as electrophotography and electrostatic recording.

[Conventional technology]

Among the image forming methods described above, an important technique is a method of forming a multicolor image.

Conventionally, in order to form a multicolor image using PIi electrophotography, the steps of charging, principle, development, and transfer are repeated for each color component, and toner images of each color are superimposed on recording paper. i.e. blue,
An electrostatic latent image is formed according to color component data such as green and red.
, develop with toner such as yellow, magenta, cyan, or black, and transfer this to a transfer material.The above steps are performed for each color component to create a multicolor image on a transfer material such as recording paper or other overhead projector film. form an image.

(2) Each time the development of each color is completed, it is necessary to transfer the image to a transfer material, which increases the size of the device and increases the time required for image formation.

■ There are drawbacks such as the tendency for positional deviations to occur due to repeated movements.

Conventional Example 2 (Improvement of Conventional Example 1) There is a multicolor image forming method that solves the above drawback by superimposing and developing multiple toner images on the same image forming body such as a photoreceptor so that only one transfer step is required. .

Problems with Conventional Example 2 There are problems such as the toner image formed by the previous stage development being disturbed during the latter stage development, and the toner from the toner image developed in the former stage being mixed into the latter stage developer, destroying the color balance. be.

Conventional Example 3 (Improvement of Conventional Example 2) In the method of Conventional Example 2, a bias with an alternating current component superimposed is applied to the developing device during the second and subsequent development to reduce the electrostatic latent image formed on the image forming body. The present inventor has proposed a method of forming a multicolor image by employing a method of causing toner to fly.

In this method, the developer layer does not rub the toner image formed up to the previous stage, so that image disturbance does not occur.

The principle of this multicolor image forming apparatus will be explained below with reference to chart 70 in FIG. FIG. 7 shows changes in the surface potential of the image forming body, taking as an example the case where the charging polarity is positive. pH indicates the exposed area of the image forming body, DA indicates the unexposed area of the low formation body, and DUP indicates the increase in potential caused by the adhesion of the positively charged toner T1 to the pH of the exposed area during the first development.

The image forming body is uniformly charged by a scorotron charger and has a constant positive surface potential E as shown in (2). Next, a first image n light is applied using a laser, cathode ray tube, LED, etc. as an exposure source, and as shown in (2), the potential of the exposed portion PH decreases according to the amount of light. The electrostatic latent image formed in this way is shown on the surface of the dark area W! A developing device to which a positive bias approximately equal to the potential E is applied performs development. the result,
As shown in (2), the positively charged toner T1 adheres to the exposed area pH where the potential is relatively low, and a first toner image T1 is formed. The area where this toner image T is formed is the positively charged toner T.
, the potential increases by DUP due to the adhesion of ,
It does not have the same potential as the unexposed area DA. Next, the surface of the image forming body on which the first toner image has been formed is charged a second time by a charger, and as a result, the surface potential E becomes uniform regardless of the presence or absence of toner. This is shown in ■. A second image exposure is performed on the surface of this image forming body to form an electrostatic latent image (■), and in the same manner as in (■) above, a positively charged toner image of a color different from the toner T is formed. Development is performed to obtain a second toner image. This is shown in ■. By performing the above process multiple times, a multicolor toner image is obtained on the photoreceptor. A multicolor recorded image can be obtained by transferring this onto recording paper and further fixing it by heating or applying pressure. In this case, the toner and charges remaining on the surface of the image forming member are cleaned and used for the next multicolor image formation.

In the method illustrated in FIG. 7, at least the developing step (2) is carried out in such a way that the developer layer does not come into contact with the surface of the image forming member.

Note that in the multicolor image forming method, the second and subsequent charging steps can be omitted. Furthermore, the exposure sources used for each image exposure may be the same or different.

In the multicolor image forming method, for example, yellow.

Toners of four colors, magenta, cyan, and black, are often superimposed on an image forming body for the following reason. According to the principle of the subtractive color method, a black image should be obtained by overlapping the three primary colors of yellow, magenta, and cyan, but the toners for the three primary colors that are put into practical use have ideal absorption wavelength ranges. In addition, due to misalignment of the toner images of the three primary colors, it is not only difficult to reproduce the clear black required for characters and lines with only these three primary color toners, but also the density of color images is They tend to run out. Therefore, as described above, a multicolor image is formed using four colors, which are the three primary colors plus black.

In electrophotography, gas or semiconductor laser light, LED, CRT, liquid crystal, etc. are used as exposure means.

In addition to the above-mentioned electrophotographic method, methods for forming latent images for multicolor image formation include a method in which an electrostatic latent image is formed by injecting charges directly onto the image forming body using a multi-needle electrode, and a magnetic method. A method of forming a magnetic latent image using a head can be used.

FIG. 8 shows an example of a device that implements this method.

In this device, a multicolor image is formed as follows. The surface of the photoreceptor 1 is uniformly charged by a sufrotron charging electrode 2. Subsequently, the image forming body 1 is irradiated with image exposure light from the laser optical system 10 . In this way, an electrostatic latent image is formed. This electrostatic latent image is developed by a developing device A containing yellow toner. The image forming body 1 on which the toner image has been formed is uniformly charged again by the Suflotron charging electrode 2 and subjected to image exposure. The formed electrostatic latent image is developed by a developing device B containing magenta toner. As a result, a two-color toner image of yellow toner and magenta toner is formed on the image forming body 1. Thereafter, the cyan toner and the black toner are developed in a similar manner, and a four-color toner image is formed on the image forming member 1. This four-color toner image is Obi i! A charge is given by the pole 9, while the charge on the image forming member 1 is dissipated by the exposure lamp 3 and then transferred to the transfer pole 4.
The image is transferred onto the transfer material P. The transfer material P is separated from the image forming body 1 by the separation pole 5 and fixed by the fixing device 6. on the other hand,
The image forming body 1 is cleaned by a removing electrode 7 and a cleaning device 8.

The cleaning device 8 has a cleaning blade 81 and a fur brush 82. These are kept out of contact with the image forming body 1 during image formation, and when a multicolor image is formed on the image forming body 1, they come into contact with the image forming body 1 and scrape off residual toner after transfer. Thereafter, the cleaning blade 81 separates from the image forming body 1, and a little later, the fur brush 82 separates from the image forming body 1. The fur brush 82 is the cleaning blade 81
When the toner leaves the image forming body 1, it functions to remove the toner remaining on the image forming body 1.

The laser optical system [0 is shown in FIG. In the figure, O is a semiconductor laser oscillator, ρ is a rotating polygon mirror, and n is an fθ lens.

In this multicolor image forming apparatus, one color is developed each time the image forming member 1 rotates once, but the application of a large alternating current voltage that contributes to development to developing devices that are not in use is stopped. During image formation, each electrode other than charging electrode 2, paper feeding, paper transport,
None of the cleaning devices 8 acts on the image forming body 1.

In the conventional method described above in Conventional Example 3, the Cowana transfer method is used as the transfer method.

This has the following advantages: ■ The mechanism is simple; ■ It does not damage the image forming body 1; ■ The toner attached to the transfer means does not stain the back surface of the transfer material P. The adhesion between the image forming member 1 and the image forming member 1 is incomplete, which tends to cause uneven transfer; ■ The transfer characteristics tend to change due to the influence of the surrounding environment, such as humidity; O The toner image in the middle of image formation is at the transfer position. When passing through the toner, the toner adheres to the SI4 and the transfer efficiency decreases.■ In places where multiple types of toner overlap at the same position, it is difficult for the lower toner to transfer.■ The position of the toner may shift during transfer. There were problems such as toner scattering and disturbing images, and these problems remained unsolved.

Conventional Example 4 Instead of the transfer pole 4 in the multicolor image forming apparatus shown in FIG.
There is a method of transferring a toner image by using a transfer means in which a roller or a belt is brought into pressure contact with the image forming body 1, and conveying a transfer material P to a pressure contact position. A method is used to increase the transfer efficiency by applying a transfer bias to these rollers and belts, or injecting charges by corona discharge or the like to form an electric field at the transfer position.

[Problem that the invention seeks to solve]

By using such a transfer means, the problems encountered when using corona discharge are improved; for example, (1) the already formed toner image adheres to the transfer means, which stains the back surface of the transfer material P; C The difference in m speed between the image forming body 1 and the transfer means may cause the transfer material P to wrinkle or the transferred image to be misaligned. ■ The transfer bias or electric charge may leak from feces on the image forming body 1, causing scratches. There are several important problems that need to be solved, such as increasing the size and lowering the transfer efficiency.

[Means for solving the gap]

(Object of the Invention) The present invention solves the above-mentioned problems, and provides an image forming method that provides a good transfer state, does not stain the transfer material, and as a result, can always obtain high-quality recorded images. The purpose is to provide such equipment.

(Structure of the Invention) The present invention provides the following features: (1) Keeping the image forming body and the transfer means in non-contact\After forming a toner image on the image forming body, forming a new toner image on the toner image. and a step of bringing the image forming body and the transfer means into contact, and after the two steps,
An image forming method, wherein the transfer means holds the transfer material and transfers the toner image to the transfer material at once; a means for forming an image; at least one means for developing the latent image to form a toner image; The above object is achieved by an image forming apparatus equipped with a transfer means for transferring the image.

[For production]

The marks in FIG. 1 show an example of a multicolor image forming apparatus based on the present invention, and the same parts as in FIG. 8 are given the same reference numerals.

The difference from the conventional multicolor image forming apparatus shown in FIG. 8 is the transfer section, and the multicolor image forming apparatus according to the present invention operates as follows.

(1) The surface of the image forming body 1 having a photoconductive photosensitive layer is uniformly charged by the charging electrode 2.

(The image forming body 1 is irradiated with image exposure light from the two laser optical system 1O, and as a result, an electrostatic latent image is formed.

(3) This electrostatic latent image is developed by a developer bag WIA containing, for example, yellow toner.

(4) The image forming body 1 on which the toner image has been formed is neutralized by emitting light from the static eliminating lamp 3, and then uniformly charged again by the charging electrode 2 and subjected to imagewise exposure.

(5) The formed electrostatic latent image is developed by a developing device B containing, for example, magenta toner, and as a result, a two-color toner image of yellow toner and magenta toner is formed on the image forming body 1. .

(6) Similarly, the cyan toner and the black toner are developed in a superimposed manner to form a four-color toner image on the image forming body 1.

(7) The four-color toner image is charged by the charging electrode 9,
Further, the charge on the image forming body is erased by the charge eliminating lamp 3.

(8) On the other hand, the transfer roller is located away from the image forming body 1 until the three-color toner image passes through the transfer position.

(9) Thereafter, a fourth color toner image is formed, and its leading edge contacts the image forming body before reaching the transfer position. Here, the contact of the transfer roll with the image forming body 1 is preferably t = o, oi seconds to 1.0 seconds before the start of transfer. .

considered to be seconds.

(The transfer material P of l is transferred between the image forming body 1 and the transfer roller from the paper feeder 11 to the paper feed roller minor and the timing roller 13.
transported by.

(11) A bias voltage is applied to the transfer roller.

(12) The transfer material P is conveyed as the image forming body 1 and the transfer roller rotate, and the transfer is completed. Here, the timing of contact of the transfer roll with the image forming body 1 by the eccentric force is controlled by the control means 14 in relation to the timing roller 13 and the transfer bias.

(13) The transfer material P is separated from the image forming body 1 by a separation tool or the like, and is fixed by the fixing device 6.

(14) Meanwhile, the image forming body 1 is cleaned by the removing electrode 7 and the cleaning device 8. The cleaning device 8 has a cleaning blade 81 and a fur brush 82. These are kept out of contact with the image forming body 1 during image formation,
When a multicolor image is formed on the photoreceptor 1, it comes into contact with the image forming member 1,
Scrape off any residual toner. Thereafter, the cleaning blade 81 separates from the image forming body 1, and a little later, the fur brush 82 separates from the image forming body 1. The fur brush blades serve to remove toner remaining on the image forming body 1 when the cleaning blade 81 leaves the image forming body 1 .

(15) At the same time, the transfer plate is separated from the image forming body 1.

In the above professional sevens, the transfer roller father is the third color (-
During transportation, the toner image (one color before the multicolor toner image is completed) comes into contact with the image forming body 1 after passing through the transfer position, so the back surface of the transfer material P is contaminated due to toner adhering to the transfer roller. It has the effect of preventing It is desirable that the bias applied to the transfer roller father for transfer is not applied until just before the transfer material P reaches the transfer position, and furthermore, when not transferring, a bias of the same polarity as the charge of the toner is applied to prevent toner from adhering. It is effective to do so.

Preferred conditions regarding the transfer roller include: ■ Image forming body 1
be in close contact with the object with a constant pressure.

■ Toner easily separates from the surface.

■ Easily generate a uniform and sufficiently large electric field in the transfer area.

Examples include. In order to satisfy this, (6)
The shaft is a strong hollow cylinder made of aluminum or similar conductive metal.

(@ Use a conductive rubber such as silicone rubber, polyurethane rubber, or butyl rubber with a thickness of about 0.5 to 5 mm as an elastic layer around it.

The resistivity of the conductive rubber is desirably less than 1%, and more preferably less than lσ0, for the purpose of (1) above. It is desirable that the hardness is within the JIB standard (K6301/Doll). Also, the applied bias voltage is
In order to prevent leakage from scratches, etc., spreading the scratches and preventing a sufficient electric field from being generated in the transfer area, it is necessary to Lay down the dielectric layer.

This is desirable. In any case, in order to maintain good adhesion to the image forming body 1, it is desirable that the surface roughness be 100 βm or less.

In order to remove the toner adhering to the transfer roller surface, it is necessary to clean the roller surface with a blade, fur brush, etc. These blades and fur brushes are
There is no problem even if it is always in contact with the surface of the transfer roller (material). In addition, as the transfer means, a belt-shaped one can be used in addition to this.

The bias voltage applied to the roller during transfer depends on various conditions, but is usually set within the range of ±0.5 to 4 KV. Further, sufficient adhesion can be obtained by setting the pressure when the transfer roller gloss contacts the image forming body 1 within the range of 0.1 to 1.5 Kf/cd.

An enlarged sectional view of the transfer section as described above is shown in FIG. 1(B). Here, a state in which it is in contact with the image forming body 1 is shown by a solid line, and a state in which it is not in contact is shown by a dotted line.

A lever 55 is arranged on the shaft 51 and supports the shaft 52. The lever group is also receiving a downward force due to the spring %. Eight tubular rollers are rotatably arranged on the shaft 52 using ball bearings.

The transfer roller connection is provided on the roller core 53.

The roller core & is supported by an eccentric force. The eccentric force worm is eccentrically rotated by rotating its axis by a motor (not shown). Therefore, the rotation of the eccentric force worm changes the roller gloss and the distance from the I forming body 1. Also, the transfer roller father surface is cleaned by the blade m. This blade 57 is always in contact with the roller father surface.

Note that since the transfer roller gloss is rotatable, when it comes into contact with the rotating image forming body 1, it rotates as a result.

Here, the features of the present invention are as follows. That is, after the toner image of one color before the completion of the multicolor toner image has passed the transfer position, and preferably immediately before the multicolor toner image is transferred, the transfer roller unit performs image formation by the action of the eccentric force roller or the like. Since the transfer roller is brought into contact with the image forming body 1 and rotates following the image forming body 1, (1) the transfer roller will not damage the toner image and will not be contaminated by the toner.

Therefore, the occurrence of stains on the back side of the transfer material is also avoided.

(2) In addition, the transfer material fed at the same timing as the transfer is smoothly transferred to the transfer area by the transfer roller which is driven to rotate first.

Next, preferred development conditions in the present invention will be explained.

The four developing devices used in the multicolor image forming apparatus shown in FIG. 1(A) may be of the same or similar structure. As an example, a sectional view of the first developing device A is shown in FIG. Developer D
e is conveyed in the direction of the arrow by the rotation of the sleeve 42 and the magnetic roll 41 having 12 poles. Developer De
The developer layer is formed into a constant thickness developer layer by the spike control blade 43 during conveyance. A stirring screen L-45 is provided in the developer reservoir handle to sufficiently stir the developer De. When the developer De in the developer reservoir is consumed,
The toner supply roller 46 rotates and the toner hopper 47
Toner T is used for fusuma painting. A power source 48 for applying a developing bias is connected to the sleeve 42 . Further, the sleeve 42, magnetic row A/41, and stirring screw 45 are driven by a motor 49 integrated with the developing device.

On the other hand, there are two types of developer: a two-component developer mainly composed of non-magnetic toner and a magnetic carrier, and a one-component developer composed only of magnetic toner, and either one may be used in the present invention. In particular, two-component developers require control of the amount of toner relative to the carrier; however, ■ Toner charge control is easy. ■ There is no need to include a large amount of black magnetic material in the toner, so color toner without color turbidity can be produced. There are advantages such as being able to

Preferred structural examples of the above-mentioned two-component developer will be given below.

Toner■ Thermoplastic resin (binder) 80-90vt% Examples: Bo-styrene, styrene acrylic polymer, Ho.

Polyester, polyvinyl butyral, epoxy resin, polyamide resin, polyethylene, ethylene vinyl acetate copolymer, etc., or mixtures of the above C @ Pigment (coloring agent) 0 to 15 wt% Examples: Black: carbon black Yellow: benzidine derivative magenta; Rhodamine B Lake, Carmine 6B, etc. Cyan: Copper phthalocyanine, sulfonamide dielectric dye, etc.■ Charge control agent 0-5wt% Positive donor: Nigrosine-based electron donating dye, alkoxylated amine, alkylamide, chelate, pigment, quaternary ammonium salt, etc. Negative toner: Electron-accepting organic complex, chlorinated paraffin, chlorinated polynistyl, excess acid group ester, chlorinated steel phthalocyanine, etc. ■ Examples of fluidizers: Colloidal silica, hydrophobic silica, silicone varnish, metal soap, Nonionic surfactants, etc. ■ Cleaning agents (prevents toner filming on the image forming body 1) Examples: Fatty acid metal salts, silicic acid oxides with organic groups on the surface, fluorine surfactants, etc. ■ Fillers (image Examples: calcium carbonate, clay, talc, pigments, etc. In addition to these materials, magnetic powder may be included to prevent fogging on the image surface and toner scattering.

As such magnetic powder, triiron tetroxide, r-ferric oxide, chromium dioxide, nickel/I/ferrite, iron alloy powder, etc. with a particle size of 0.1 to 1 m are used, and the powder is 5 to 70 wt%.
Contains. The resistance of toner varies greatly depending on the type and content of magnetic powder, but in order to obtain a sufficient resistance of tol 001 or more, preferably 012 ΩG or more, the amount of magnetic material should be 55 wt% or less to maintain clear colors. In order to achieve this, it is desirable that the content be 30 wt% or less.

Suitable resins for pressure fixing toners that are plastically deformed and fixed to paper with a force of about 20 to 6 r/ffi include adhesive resins such as wax, polyolefins, ethylene acetic acid, vinyl copolymers, polyurethane, and rubber. etc. are used.

A toner can be made using the above-mentioned materials by a conventionally known manufacturing method.

In this apparatus, in order to obtain a more preferable image, it is desirable that the toner particle size (weight average) is about 1.5 μm or less. Furthermore, it is desirable to prevent toner scattering.

Note that the weight average particle diameter is a value measured with a Coulter Counter (manufactured by Coulter Co., Ltd.). In addition, the specific resistance of the particles is determined by placing the particles in a container with a cross-sectional area of 0.507, tapping the particles, applying a load of IKII/- on the packed particles to make the thickness about 1 cm, and comparing the load and the bottom surface. 10 between the electrodes
It is determined from the current value that flows when an electric field of 2 to 5v 7' cm is generated.

Carrier Basically, the materials listed as the constituent materials of the toner are used.

The carrier particles are mainly composed of magnetic particles and resin, and are preferably spherical in order to improve resolution and VA tone reproducibility, and have a weight average particle diameter of 50 μm or less, particularly preferably 5 μm or more. The following are preferred:

In addition, in order to prevent charges from being injected by bias voltage and carriers from adhering to the surface of the image forming body and from disappearing charges that form a latent image, the resistivity of the carrier is set to 10.
An insulating material with an insulation resistance of 10 Ω or more, preferably 10120 cm or more, and more preferably 0.14 Ω or more is preferable.

Such a carrier is produced by coating the surface of a magnetic material with a resin, or by dispersing the magnetic material and fine particles in a resin, and selecting the resulting particles using a known particle size selection means.

Furthermore, when the carrier is to be made into a spherical shape, it is carried out as follows.

■Resin carrier: Select spherical magnetic particles.

■Magnetic Powder Dispersion Carrier After forming the bidisperse resin, perform a spheroidization process using hot air or hot water, or directly form a spherical dispersed resin using a spray drying method.

Next, the developing method will be explained.

In the present invention, it is desirable to use a non-contact development method in which the developer layer on the sleeve 42 does not rub against the surface of the image forming body for at least the second and subsequent development. In the non-contact developing method, when there is no developing bias between the image forming body 1 and the sleeve 42, the thickness of the developer layer in the developing area is smaller than the gap between the image forming body 1 and the sleeve C. It is set so that In this case, the amplitude of the AC component of the developing bias applied to the sleeve 42 is vAc (v), the frequency is f (Hz), and the distance between the image forming body 1 and the sleeve is d.
(llIl), development with -component developer is 0
．． 2≦vAc/(d-f)≦1.6 Development with a two-component developer is performed under the condition of 0.2≦vAc/(d-f) ((vhc/'d)15001/f≦1.0. It is desirable to do so.

The above desirable conditions were determined for the following reasons. The present inventor conducted an experiment in which another toner image was superimposed on an image forming member 1 on which a toner image had been formed by non-contact development while changing conditions. FIG. 3 shows the results using a -component developer. The figure shows the frequency of the AC component on the horizontal axis and the amplitude (half between peaks) of the electric field (potential difference divided by distance) on the vertical axis. Areas where the effects of the components are not sufficient, ■ are areas where the toner image already formed on the image forming body is likely to be destroyed,
■ is an area where the toner image that has already been formed is not likely to be destroyed, and is fully developed.
is particularly well developed.

Moreover, FIG. 4 shows the results using a two-component developer. The symbols in the figure represent the same meanings as in Figure 3. As the two-component developer, one under the preferable conditions described above was used.

As a result of the above, the above-mentioned preferable developing conditions were obtained, but in the case of a -component developer, the toner image was further reduced under the condition of 0.4≦VAC/'(d-f)≦1.2. It will not be destroyed, and furthermore, if 0.6≦vAc//cd, f)≦1.0 is satisfied, sufficient image density can be obtained. In addition, when using a two-component developer, the toner image will not be destroyed under the condition of 0.5≦vAc/(d,f) ((vAC/a) -1500) /l≦1.0, Further, if 0.5≦vAc/(d−f) ((VAc/d) −15001/f≦0.8 is satisfied, sufficient image density can be obtained.

〔Example〕

EXAMPLES Hereinafter, the present invention will be specifically explained with reference to Examples, but the embodiments of the present invention are not limited thereto.

1, 2, 5, 6, and 9 are diagrams for explaining this embodiment. FIG. 5 is a block diagram showing the image forming system of this embodiment, and FIG. 6 is a block diagram showing the image forming system of this embodiment. 3 is a timing chart of the image forming process of this embodiment. Further, Tables 1 to 4 show specific setting conditions necessary in this embodiment.

First, the formation of a multicolor image in this embodiment is performed according to the image forming system shown in FIG. That is, the data obtained by the image data input section (FIG. 5 (a)) in which the image sensor scans the original image is processed by the image data processing section (FIG. 5 (b)) equipped with a computer to create an image. Data is created and temporarily stored in an image memory (FIG. 5(c)), which is a magnetic disk. The image memory is then taken out during recording and inputted into the multicolor image forming apparatus shown in FIG. 1(a), which is a recording section (FIG. 5(d)).

In recording by the multicolor image forming apparatus, first, a Suflotron charger 2 uniformly charges an image forming member 1 having a photoconductive photosensitive layer rotating in the direction of the arrow. Next, the charged surface is subjected to image exposure obtained by modulating the laser device having the configuration shown in FIG. 9 with the image data retrieved from the image memory (!: g4 (c)). to form an electrostatic latent image.

This electrostatic latent image is developed by a reversal development method using the developing device shown in FIG. 2 containing the two-component developer to form a toner image. This image forming process is repeated by rotating the image forming member 1 four times for each color of yellow, magenta, cyan, and black, thereby forming a multicolor toner image in which the toner images of each color are superimposed. This multicolor toner image is charged by the pre-transfer charger 9 to be easily transferred, and then
As shown in the table, before the start of transfer, the transfer roll mark is brought into contact with the image forming body 1 to be rotated, and is fed from the paper feeder 11 via the paper feed roller 2 and timing roller 13 in synchronization with image formation. The transfer material P shown in Fig. 1 (B
), preferably -0,
Transfer is performed by applying a transfer bias in the range of 5 to -3 KV.

Specific image forming conditions, developer, developing conditions, and transfer conditions required for the formation of the multicolor toner image and roll transfer described above are shown in Tables 1 to 4 below.

Note that three types of transfer roll groups, A1, A2, and flat 3, are prepared, and the conditions are set for each transfer roll in Table 4 above.

Further, the structure of the transfer roll is, for example, as follows.

That is, an elastic layer with a thickness of 1 mm is provided on the outer periphery of a core metal having a diameter of 2811I, and an elastic layer with a thickness of 50 μm is further provided on the outer periphery.
Table 2 Table 2 onwards, square F margin, ・' Table 3 onwards, bottom margin 4 Table The transfer material P to which the multicolor toner image has been transferred is separated from the transfer roll gloss and heated and fixed by the fixing device 6. Ru. On the other hand, the post-transfer image forming body 1 is neutralized by the pre-cleaning static eliminator 7, and then the blades 81 and 7 of the cleaning device 8
Residual toner is cleaned by a wiper 82 in preparation for the next image formation. Charging, image exposure, development, transfer, and image formation associated with the 10 rotations of the image forming body in the solid multicolor image forming process described above.

The leaning operation timing is shown in FIG.

In FIG. 6, the horizontal axis shows the rotational speed and elapsed time of the image forming body 1 in seconds, and the vertical axis shows each step for image formation.

In addition, T in Figure 1 is the time when the leading edge of the transfer material P comes into contact with the transfer roll mark and the image forming body 1, which coincides with the start of the transfer, and T/ is the time when the leading edge of the transfer material P comes into contact with the transfer roll mark and the image forming body 1. t is the time difference between the two. Through the above image forming process, a copy of an extremely clear multicolor image was obtained without any transfer deviation.

〔Effect of the invention〕

As explained above, the present invention provides a means for transferring a multicolor toner image formed on an image forming body by using an elastic member and an insulating member (dielectric material) on a surface that is brought into contact with the image forming body while supporting the transfer material. Since the transfer means is brought into contact with the image forming body immediately before transfer, the toner on the image forming body does not adhere to the transfer means, and the transfer material Does not stain the back of the device.

(2) Wrinkling of the transfer material or misalignment of the image does not occur due to the difference in S speed between the image forming body and the transfer means.

■ Bias and charge for transfer do not leak due to scratches on the image forming body.

■ Since toner images are transferred using both physical and electrical effects, transfer efficiency is high and high-quality recorded images can be obtained.

There are effects such as

[Brief explanation of the drawing]

FIG. 1(a) is a sectional view showing a multicolor image forming apparatus according to the present invention, FIG. 1(b) is an enlarged sectional view of a transfer section, and FIG.
3 is a graph showing the developing conditions using a one-component developer; FIG. 4 is a graph showing the developing conditions using a two-component developer; FIG. 5 is a block diagram showing the image forming system, and FIG. 6 is a timing chart of the image forming process. Further, FIG. 7 is a flowchart of image formation as a conventional technique, FIG. 8 is a sectional view of a multicolor image forming apparatus as a conventional technique, and FIG. 9 is a sectional view of a laser device. DESCRIPTION OF SYMBOLS 1... Image forming body, 2... Scorotron charger, 3... Exposure lamp, 6... Fixing device. 7... Pre-cleaning static eliminator, 8... Cleaning device, 81... Blade, 82
...7 aplash, 9...pre-transfer charger, 10.
...Laser device, 11...Paper feeding device, 12...
Paper feed roller, 13...timing roller, 14
... timing control device, 21 ... laser oscillator,
η...Rotating polygon mirror, n...fa lens, A, B
, C, D...Developer, P...Transfer material, 41...
Magnetic roll, 42... Sleeve, 43... Spilling regulation blade, ■... Developer reservoir, 45... Stirring screw, 46... Toner supply roller, 47... Toner hopper, 48...・Developer's ear, (fund)...Transfer roller, 51...Renoku single shaft, 52...Transfer roller shaft, Group...Roller core, She...Eccentric cam, 5
5...Renogu, Seki...Spring, 57...Blade, Akira...Eccentric camshaft. Applicant Konishiroku Photo Industry Co., Ltd. Figure 1 (A)

Claims (7)

[Claims] (1) After forming a toner image on the image forming body while keeping the image forming body and the transfer means in non-contact, forming a new toner image on top of the toner image, and forming a new toner image on the image forming body; and a step of bringing the toner image into contact with the transfer means, and after the two steps, the transfer means holds the transfer material and transfers the toner image to the transfer material all at once. An image forming method characterized by: (2) The image forming method according to claim 1, wherein the transfer means is a transfer roller, and when the transfer roller comes into contact with the image forming body, it rotates following the movement of the image forming body. . (3) The image forming method according to claim 1, wherein the toner image formed on the image forming body is a multicolor toner image formed by overlapping toner images of a plurality of colors. (4) a rotating image forming body, a means for forming a latent image on the image forming body, at least one means for developing the latent image to form a toner image, and a means for forming a toner image on the image forming body immediately before transfer; An image forming apparatus comprising: a transfer unit that contacts the transfer material and transfers the toner image onto the transfer material while holding the transfer material. (5) The image forming apparatus according to claim 4, wherein the transfer means is a transfer roller, and when the transfer roller comes into contact with the image forming body, the image forming apparatus rotates following the rotation of the image forming body. . (6) The image forming apparatus according to claim 5, wherein the transfer roller comprises a shaft, an elastic member covering the outer periphery of the shaft, and a dielectric layer covering the outer periphery of the elastic member. (7) The image forming apparatus according to claim 4, wherein the toner image formed on the image forming body is a multicolor toner image formed by overlapping toner images of a plurality of colors.