JP2002328502A - Color image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a color image apparatus which can form a color image with high glossiness equivalent to that obtained by a silver halide photographic paper photograph and causing no structure such as a boundary line appearing on the image surface on a transfer body. SOLUTION: In the apparatus, a transparent toner image consisting of transparent toner is formed in an area where the color image is not formed and the transparent toner image consisting of the transparent toner is formed to be overlapped party in a part where the density of the color image is rapidly varied.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color image forming apparatus for forming a color image by using a powder toner by an electrophotographic system or an electrostatic recording system, and more particularly to a color image forming device having good glossiness. The present invention relates to a color image forming apparatus that can be formed.

[0002]

2. Description of the Related Art Conventionally, when a color image is formed by such an electrophotographic system or an electrostatic recording system, for example, the following image forming process is performed. First, the color original is illuminated, the reflected light image is separated and read by a color CCD, and predetermined image processing and color correction are performed by an image processing device, and based on the obtained multi-color image signals,
For example, a semiconductor laser or the like is modulated for each color, and a laser beam modulated according to an image signal of each color is emitted from the semiconductor laser. By irradiating this laser beam multiple times, one color at a time, onto an inorganic photoreceptor such as Se or amorphous silicon, or an organic photoreceptor using a phthalocyanine pigment, bisazo pigment, or the like as a charge generation layer, a plurality of electrostatic latent images are formed. Form. A plurality of electrostatic latent images formed on the inorganic or organic photoreceptor are formed by, for example, yellow (Y),
Magenta (M), Sian (C), and Black (K)
Are sequentially developed with the four color toners. The developed toner image is transferred from an inorganic or organic photoreceptor onto a transfer member such as paper, and is heated and fixed by a fixing device including a heat fixing roll or the like, whereby a color image is formed on the transfer member. .

A color toner used in such a color image forming apparatus is prepared by dispersing a colorant in a binder resin composed of, for example, a polyester resin, a styrene / acrylic copolymer, a styrene / butadiene copolymer, or the like. Particles having an average particle size of 1 to 15 μm,
Fine particles, for example, inorganic fine particles such as silicon oxide, titanium oxide, and aluminum oxide, or PMMA, PVD
It is obtained by adhering fine resin particles such as F.

Examples of the coloring agent include benzidine yellow, quinoline yellow, and Hansa yellow as yellow (Y), rhodamine B, rose bengal, and pigment red as magenta (M), and phthalocyanine blue as cyan (C). , Aniline blue,
For example, carbon black, aniline black, a blend of color pigments, and the like are used as black (K) such as pigment blue.

Meanwhile, an image formed by a color image forming apparatus of an electrophotographic method using a silver halide photograph as an original has a high density because the amount of toner attached thereto is increased or decreased in accordance with the density of the silver halide photo original. Since the part has a large amount of toner attached,
The glossiness becomes high, and conversely, the low density portion has a low toner adhesion amount, so that the glossiness becomes low.
Therefore, the degree of glossiness of a color image is proportional to the image density of a color original, and an image having a glossy surface different from that of a silver halide photographic paper used as an original is obtained. There was a point.

Therefore, in order to solve the above-mentioned problems, for example, Japanese Patent Application Laid-Open Nos. 04-278967, 04-362960, 07-5738, 09-005551 and JP-A-10-2
As disclosed in Japanese Patent No. 13942, a method of transferring and fixing a transparent toner on a transfer member in addition to a color toner has been proposed.

[0007]

However, the prior art described above has the following problems. That is, JP-A-04-278967, JP-A-04-362960, JP-A-07-5538, JP-A-09-200551, and JP-A-10-2
As disclosed in Japanese Patent Application Laid-Open No. 13942/1999, in the case of a method of transferring and fixing a transparent toner on a transfer member in addition to a color toner, an image portion made of a color toner and an image portion made of a transparent toner When multiple transfer is performed, there is a problem that as shown in FIG. 6, unevenness 102 is formed at the boundary between the color toner portion 100 and the transparent toner portion 101 due to a slight positional shift (registration shift). I was

When the transparent toner is used so that the developing toner amount becomes substantially constant, the developing amount of the transparent toner becomes significantly larger than that of the color toner. For example, in a color image forming apparatus using four color toners of yellow (Y), magenta (M), sian (C), and black (K), the development amount of the transparent toner in the non-image portion is one color. The amount of toner development reaches about four times. In such a color image forming apparatus, there has been a problem that a gap between the color image portion and the transparent toner portion is formed due to the misregistration of the transparent toner, which greatly affects the surface shape of the image. In particular, there is a problem that a structure like a boundary line 102 shown in FIG. 6 occurs between an image part having a high density and an image part or a background part having a low density, and the image quality of a color image is reduced. Had a point.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and it is an object of the present invention to provide the same glossiness as a silver halide photographic paper photograph, An object of the present invention is to provide a color image forming apparatus capable of forming a color image in which a structure such as a boundary does not appear on an image surface on a body.

[0010]

Means for Solving the Problems In order to achieve the above object, the present inventors conducted a structural analysis of the image, and as a result, it was found that the structural lines seen in the image formed on the transfer body had a high density. Is caused by a gap between the color toner image and the transparent toner image due to misregistration between the color toner and the transparent toner at a boundary portion (pixel end portion) between the portion and the low density image portion or the background portion. I found that.

The inventors of the present invention have studied the means for achieving the above object, and as a result, have increased the amount of the transparent toner in the portion where the density of the color toner image changes rapidly, that is, The present inventors have found that by performing a process of superimposing a transparent toner image on a toner image, it is possible to eliminate an image defect due to misregistration, and reached the present invention.

As a means for adding and outputting a transparent toner image to a portion where the density of a color toner image changes rapidly, an edge emphasis effect at the time of development can be used. In generating an image, it is desirable that the image forming apparatus be provided with an image processing device that detects a portion where the density of the color toner image area changes rapidly.

According to a first aspect of the present invention, there is provided a single or a plurality of image carriers on which a plurality of toner images of different colors are formed based on image information of a color image; Image processing means for generating image information to form an image with a transparent toner based on the image information generated by the image processing means. A transparent toner image forming means for forming an image, and a transfer means for transferring a plurality of toner images of different colors and a transparent toner image formed on the image carrier onto a transfer body directly or via an intermediate transfer body And fixing means for fixing the plurality of different color toner images and the transparent toner image on a transfer member, wherein the area where the color image is not formed is formed by using a transparent toner. To form a that transparent toner image, the portion where the concentration of the color image is rapidly changed, a color image forming apparatus, and forming so as to partially overlap the transparent toner image formed of transparent toner.

According to a second aspect of the present invention, the image processing means detects a portion where the density of the color image changes abruptly and overlaps the portion where the density of the color image changes abruptly. 2. The color image forming apparatus according to claim 1, wherein a transparent toner image formed of a transparent toner is formed.

Further, according to the invention described in claim 3, the image processing means detects a portion where the density of the color image changes abruptly, and sets the transparent toner image composed of the color image and the transparent toner to 0.1. 3. The color image forming apparatus according to claim 1, wherein the color image forming apparatus is set to overlap by 1 mm or more.

[0016] Still further, the invention described in claim 4 is:
4. The image forming apparatus according to claim 1, wherein the sum of the toner amount of the color image transferred onto the transfer member and the toner amount of the transparent toner image is set to be 150% or less of the maximum toner amount of the color image. 3. The color image forming apparatus according to any one of 3.

Further, according to the invention described in claim 5, the image processing means detects a portion where the density of the color image changes rapidly, and tilts to a portion where the density of the color image changes rapidly. The color image forming apparatus according to claim 1, wherein a transparent toner image made of a transparent toner is formed so as to overlap in a state.

[0018]

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

Embodiment 1 This color image forming apparatus includes a single or a plurality of image carriers on which a plurality of toner images of different colors are formed based on image information of a color image; An image processing means for generating image information to form an image with a transparent toner based on the image information, and a transparent toner on the image carrier or a different image carrier based on the image information generated by the image processing means. Means for forming an image by means of a transparent toner image, and transfer means for transferring a plurality of toner images of different colors and a transparent toner image formed on the image carrier onto a transfer material directly or via an intermediate transfer body And a fixing unit for fixing the toner images and the transparent toner images of the plurality of colors on a transfer material.

FIG. 2 is a configuration diagram showing a color image forming apparatus according to one embodiment of the present invention.

The color image forming apparatus 1 is roughly divided into
A document reading device 2 for reading an image of a color document, and color image data read by the document reading device 2 and color image data sent from a personal computer (not shown) are subjected to predetermined image processing and color processing. An image processing device 3 for generating image information for forming an image with transparent toner based on the image information of the image; and at least yellow (Y) and magenta based on the image information processed by the image processing device 3. (M), a color toner image using Sian (C) color toner, and an image output device 4 also serving as a transparent toner image forming means for forming a transparent toner image made of transparent toner.

The document reading device 2 illuminates a document 5 placed on a platen glass (not shown) with an illumination lamp 6 and reflects a reflected light image from the document 5 by a color CCD 7 at a predetermined dot density (for example, 16 dots / mm)
It is configured to read by.

The reflected light image of the original 5 read by the original reading device 2 is, for example, an image as original reflectance data of three colors of red (R), green (G), and blue (B) (each 8 bits). The image processing apparatus 3 sends the reflectance data of the document 5 to the shading correction, the positional deviation correction, the brightness / color space conversion, the gamma correction,
Predetermined image processing such as color / movement editing is performed,
The image data is converted into image data of three colors of yellow (Y), magenta (M), and cyan (C) (each of 8 bits). The image processing device 3 may be configured to convert not only the three colors of yellow (Y), magenta (M), and cyan (C) but also the image data of black (K).

Inside the color image forming apparatus 1, there are provided three color toner images of yellow (Y), magenta (M), and cyan (C), and an image output device 4 capable of forming a transparent toner image. It is established. The image output device 4 mainly includes a ROS 9 as an image writing unit, a photosensitive drum 10 as an image carrier on which an electrostatic latent image is formed,
Developing means for developing the electrostatic latent image formed on the photosensitive drum 10 to form a three-color toner image of yellow (Y), magenta (M), and cyan (C) and a transparent toner image A developing device 11 of a rotary type, a transfer drum 13 as a transfer member carrier which rotates while holding a transfer sheet 12 as a transfer member on the surface, and different colors sequentially formed on the photosensitive drum 10 Multiple toner images
The image forming apparatus includes a transfer corotron 14 as a transfer unit that transfers the image onto the transfer sheet 12 held on the transfer drum 13, and a fixing device 15 that fixes a toner image on the transfer sheet 12.

The image data subjected to the predetermined image processing by the image processing device 3 as described above includes image data of three colors of yellow (Y), magenta (M), and cyan (C),
As described later, the image data is converted into image data of a transparent toner (T), and these image data are converted to ROS9 (Raster).
Output Scanner).

As shown in FIG. 2, the ROS 9 modulates the semiconductor laser 8 according to image data, and the semiconductor laser 8 emits a laser beam LB modulated according to the image data. The laser light LB emitted from the semiconductor laser 8 is deflected and scanned by a rotating polygon mirror (not shown), and is scanned and exposed on the photosensitive drum 10 via an optical system including an f · θ lens and a reflection mirror.

The photosensitive drum 10 on which the laser beam LB is scanned and exposed by the ROS 9 is driven to rotate at a predetermined speed in a direction indicated by an arrow by driving means (not shown). The surface of the photoconductor drum 10 is charged to a predetermined polarity (for example, negative polarity) and a potential by a charger (for example, scorotron) 16 for primary charging in advance, and then yellow (Y) in accordance with image data. ,
An electrostatic latent image is formed by sequentially scanning and exposing the laser light LB corresponding to each color of magenta (M), cyan (C), and transparent toner (T). The electrostatic latent image formed on the photoreceptor drum 10 includes yellow (Y), magenta (M), cyan (C), and transparent toner (T).
For example, by a rotary developing device 11 having color developing units 11Y, 11M, 11C, and 11T, for example, the developing device 11 is reversely developed with a toner charged to the same negative polarity as the charged polarity of the photoconductor drum 10 to form a predetermined color. It becomes a toner image. Note that the rotary type developing device 11 may be configured to further include a black (K) color developing device.

The color toner used in the developing device 11 is, for example, a powder particle containing at least a binder resin and a colorant, such as a cyan toner, a magenta toner, and a yellow toner. The composition, average particle size, and the like of these color toners are appropriately selected from a range that does not impair the purpose of the present invention.

Examples of the binder resin include those exemplified as the binder resin in the transparent toner described later.
The binder resin has a weight average molecular weight of 5,000 to 1200.
It is preferably a polyester of 0. The colorant is not particularly limited as long as it is a colorant generally used for toner, and can be selected from per se known Sian pigments or dyes, magenta pigments or dyes, yellow pigments or dyes.

Examples of the colorant include benzidine yellow, quinoline yellow, and yellow (Y).
Hansa Yellow, etc., Rhodamine B, Rose Bengal, Pigment Red, etc. as magenta (M), Phthalocyanine Blue, Aniline Blue as Sian (C),
For example, carbon black, aniline black, a blend of color pigments and the like are used as black (K) such as pigment blue.

In order to obtain more preferable color tone reproducibility, the colorant has a primary particle diameter in the range of 0.01 to 1 μm, preferably 0.1 to 1 μm, and
It is preferable to use a resin having a size equivalent to the primary particle diameter and melt-dispersed in a resin. The colorant melt-dispersed in the resin referred to here means that the resin is melted by heating or melted in a solvent, and the wet cake of the colorant obtained in the color material forming step is kneaded to form a colorant. It is a material that is dispersed in a resin in the form of primary particles, solidified by cooling or removing a solvent, and then pulverized.

When developing a color toner, for example, an inorganic powder may be attached as fine particles for imparting fluidity to the surface of the toner particles. The inorganic powder is made of silica, titanium oxide, tin oxide, aluminum oxide, or the like commonly used in the art, and has a particle size of 0.001.
０．１0.1 μm can be used.

As the inorganic powder to be attached to the toner particles, those treated with various treating agents may be used in order to impart stability to the charging environment.

The particle size of the color toner is not particularly limited, but is preferably 3 μm or more and 10 μm or less in consideration of the function of faithfully reproducing the electrostatic latent image by the ROS 9. If it is less than 3 μm, fogging due to the low-charged toner tends to occur, and if it exceeds 10 μm, it is difficult to obtain an image with less noise and good granularity.

In the present invention, the color toner may be prepared as appropriate, or may be a commercially available product.

The color toner is used after being combined with an appropriately selected carrier known per se to form a developer. Further, as a one-component developer, a unit that frictionally charges with a developing sleeve or a charging member to form a charged toner, and develops according to an electrostatic latent image may be applied.

The toner images of the respective colors sequentially formed on the photosensitive drum 10 are transferred onto a transfer sheet 12 held on a transfer drum 13 disposed below the photosensitive drum 10.
The image is multiplexly transferred by a transfer corotron 14 as a transfer unit. The transfer drum 13 is formed of a synthetic resin film or the like formed in a cylindrical shape, and is rotatably driven in the direction of the arrow at the same moving speed as the peripheral speed of the photosensitive drum 10.

The transfer paper 12 held on the transfer drum 10 has yellow (Y), magenta (M), and yellow (Y) formed on the photosensitive drum 10 according to the color of the image to be formed.
The toner images of all or a part of the three colors of Sian (C) are transferred by the transfer corotron 15 in a state of being sequentially superimposed. The black image is formed by superimposing three color toner images of yellow (Y), magenta (M), and cyan (C). As described above, a black developing device is separately provided. Of course, a black image may be formed directly.

In this embodiment, as a method of transferring the powder toner image formed on the photosensitive drum 10 as an image carrier onto the transfer body 12, a transfer method using electrostatic force is used. Of course, a transfer method using both electrostatic force and pressure may be used. The powder toner image formed on the photoreceptor drum 10 as the image carrier may be a belt-like or drum-like intermediate image even if it is not directly transferred onto a transfer body for forming an image. After the image is transferred onto the transfer member, a method of transferring the image onto a transfer member for forming an image may be used. Further, when the powder toner image formed on the photosensitive drum 10 as the image carrier is transferred onto the transfer body via a belt-shaped or drum-shaped intermediate transfer body, the image carrier is used as an image carrier. The number of photosensitive drums is not limited to one, and may be provided in a number corresponding to the color of the color toner to be formed.

As the image carrier, for example, a photosensitive drum is used. However, the present invention is not limited to this, and a dielectric drum used in an electrostatic recording system may be used. In this case, a means for forming an electrostatic latent image directly on the dielectric drum by an ion stream or the like is used as the image writing means.

In this embodiment, a transparent toner image composed of a transparent toner is formed on the photosensitive drum 10 as an image carrier. However, in particular, when a plurality of image carriers are provided, Alternatively, another image carrier for forming a transparent toner image made of a transparent toner may be provided.

Transfer paper 12 on which the toner image is transferred
As shown in FIG. 2, is supplied from an unillustrated paper feed tray, and is provided on a roll 17 for electrostatic adsorption provided on the front side of the transfer drum 13 and on the back side of the transfer drum 13. The electrostatic charger 18 for electrostatic attraction holds the transfer drum 13 in a state of being electrostatically attracted to the surface thereof.

The transfer member 1 used in this embodiment
It is preferable to use as No. 2 a transparent resin layer or a white resin layer provided on the surface of uncoated paper / coated paper at least on the surface to which an image is to be transferred. The resin layer can be formed on uncoated paper or coated paper by a method in which a resin dissolved in a solvent is applied using an applicator or a wire bar. When the resin forming the resin layer is a polyester resin, a known solvent that can dissolve the polyester resin, such as tetrahydrafuran or methyl ethyl ketone, can be used.

As a method of forming a resin layer on non-coated paper / coated paper other than coating, a method of transferring a resin layer previously formed on a plastic film to uncoated paper or coated paper by heating and pressing. Any method can be used as long as it can form a resin layer on uncoated paper or coated paper by other methods.

Further, in this embodiment, a glossy sheet having surface smoothness, heat resistance and release properties is superimposed on the transfer body 12, and the transfer body and the glossy sheet are heated and
After applying pressure, further cooling the image receiving material and the glossy sheet, and then peeling the glossy sheet from the transfer body, it is also possible to use fixing by a cooling and peeling device, which is characterized in that it is used.

Then, as described above, the transfer paper 12 to which the toner images of a predetermined number of colors have been transferred is peeled off from the surface of the transfer drum 13 by a peeling means (not shown), and is conveyed to the fixing device 15. In the fixing device 15, a color toner image and a transparent toner image are fixed on the transfer paper 12 by heat and pressure, and a color image having excellent gloss is obtained.

In the above embodiment, the case where the toner image transfer step and the fixing step are performed separately has been described. However, the toner image transfer step and the fixing step may be performed simultaneously.

The transparent toner used in this embodiment is configured to contain at least a thermoplastic binder resin.

Examples of the binder resin include styrene resin, acrylic resin, styrene-acryl resin, styrene-butadiene resin, vinyl chloride resin, vinyl acetate resin, polyester resin, polyurethane resin, polyamide resin, epoxy resin and the like. Although it can be used, in consideration of the fixability of the powder toner image on the transfer material 12, the viscosity of the powder toner at the time of fixing is 10 ² Pa · s or more,
Those having a density of not more than 0 ⁵ Pa · s can be suitably used.
When the viscosity of the powder toner at the time of fixing is less than 10 ² Pa · s, when the toner is fixed by the fixing roll of the fixing device 15,
There is a possibility that an offset to the fixing roll may occur. Also,
If the viscosity of the powder toner at the time of fixing exceeds 10 ⁵ Pa · s, the powder toner does not melt and soften when fixed by a fixing roll, and thus adheres to the transfer material 12 and adheres to each other. Is insufficient, and it is difficult to obtain a sufficient fixing strength.

When developing the transparent toner, for example, an inorganic powder may be attached as fine particles for imparting fluidity to the surface of the toner particles, similarly to the color toner. As the inorganic powder, silica commonly used in the industry,
It is possible to use titanium oxide, tin oxide, aluminum oxide or the like having a particle size of 0.001 to 0.1 μm.

As the inorganic powder to be attached to the toner particles, those treated with various treatment agents may be used in order to impart stability to the charging environment.

Further, the average particle size of the transparent toner used in this embodiment is desirably 3 μm or more and 15 μm or less. When the thickness is less than 3 μm, fogging due to the low-charged toner is apt to occur, and a transparent toner image is formed at a place other than around a desired pixel. If it exceeds 15 μm, it becomes difficult to control the amount of the transparent toner image formed around the pixel.

The above-mentioned transparent toner is used after being combined with an appropriately selected carrier known per se to form a developer. Further, as a one-component developer, a means for forming a charged toner by frictionally charging with a developing sleeve or a charging member and developing the toner in accordance with an electrostatic latent image can also be applied.

Further, in this embodiment, from the viewpoint of toner production, the particle diameters of the color toner and the transparent toner may be the same in order to enable production under the same conditions with the same equipment.

In this embodiment, a portion where the density of a color image changes rapidly is detected by the image processing means, and a portion where the color image is not formed is detected.
While forming a transparent toner image composed of transparent toner,
A transparent toner image made of a transparent toner is formed so as to partially overlap a portion where the density of the color image changes abruptly.

That is, in this embodiment, based on the input color image data, the area where the image is to be formed by the transparent toner and the amount of the transparent toner to be developed are calculated, for example, as follows. Is done.

In this color image forming apparatus, as shown in FIG. 2, the image of the color original 5 is read by the original reading device 2, and the image information of the color original 5 read by the original reading device 2 is transmitted to the image processing device. 3 is input. In the image processing device 3, the image information of the color document 5 read by the document reading device 2 is converted into three color image signals of yellow (Y), magenta (M), and cyan (C).

The image processing apparatus calculates the amount of transparent toner to be formed for each pixel based on the three color image signals of yellow (Y), magenta (M), and cyan (C). Image processing for increasing the amount of transparent toner is performed in an area where the development amount of the color toner changes abruptly.

Here, the area where the development amount of the color toner rapidly changes is, for example, as shown in FIG. 3A, the boundary area between the plain background portion 20 where no color toner exists and the color toner image 21. As shown in FIG. 3B, a transparent toner image 23 made of a fixed amount of transparent toner is formed on the plain background portion 20 where no color toner exists and the edge portion 22 of the color toner image 21. , Part 23
a are formed so as to always overlap. The overlapping amount of the color toner image and the transparent toner image is desirably 0.1 mm or more.

The area where the development amount of the color toner changes abruptly is, for example, as shown in FIG. 4A, the color image portion 24 where a large amount of color toner exists and the color image portion where only a small amount of color toner exists. The boundary region 26 between the color image portion 25 and the color image portion 24 where a large amount of color toner exists and the edge portion 26 of the color image portion 25 where only a small amount of color toner exists are shown in FIG.
As shown in (b), a transparent toner image 23 composed of a fixed amount of transparent toner is formed such that the portions 23a always overlap.

In the area where the development amount of the color toner changes abruptly, for example, the differentiation of the density of the color toner image at each pixel is performed by using a differentiation operator for detecting a change in the density of the color toner. A portion where the density changes rapidly (edge portion) is required.

It is also possible to check the pixel value of the peripheral area of the transparent toner within a certain radius, and to detect the maximum value of the image density in the peripheral area of the certain radius. Even with this Max operator processing, the transparent toner is not added to the portion where the amount of the color toner is constant, and the transparent toner image overlaps the color toner image by the radius in the portion where the density of the color toner changes rapidly. Can be formed. The overlapping amount of the color toner image and the transparent toner image is
It is desirable that it be 0.1 mm or more.

At this time, if the total toner amount in the overlapping portion of the color toner image 21 and the transparent toner image 23 is too large, an image flow at the edge portion is caused. The sum of the quantities is
As shown in FIG. 1, it is desirable to make adjustments so that the maximum toner amount of only the color toner is 150% or less at each point of the image. In addition, the transparent toner image added to the sharply changing density portion of the color toner image by the image processing does not simply overlap the color toner image at a constant density, but the development amount gradually decreases toward the end. The color toner image 21 and the transparent toner image 2
This is desirable because it can be made less noticeable than the boundary with 3.

The image signal of each color toner obtained by the image processing as described above is converted by the image processing device 3 into an optical signal for lighting the semiconductor laser 5 of the ROS 9 according to the image density.

The generated image signal of each color toner is temporarily stored in a memory provided in the image processing apparatus 3 in order to store the image signal. The stored data includes information on whether to perform image exposure at a position corresponding to each pixel on the photosensitive drum 10 or not, and to store an image at a position corresponding to each pixel on the photosensitive drum 10. The image data when performing the exposure is stored as “1”, and the image data when not performing the image exposure is stored as “0”. Then, the surface of the photoreceptor drum 10 exposed to the image becomes a portion to be developed with the toner of the corresponding color.

When a transparent toner image is formed, the order of development and transfer with a color toner image is arbitrary. Generally, an image formed of a color toner is formed on the photosensitive drum 10 and then transferred. Finally, develop and transfer the transparent toner image,
In other words, when developing and transferring so that the transparent toner comes to the surface,
A good image with less image blur and toner scattering is obtained.

Further, the transfer amount of the color toner and the transparent toner is obtained by cutting out the unfixed image portion transferred onto the transfer member together with the transfer member, and determining the difference between the weights of the transfer member before and after removing the unfixed image with compressed air or the like. It can be obtained by setting the amount.

The average particle size of the color toner and the transparent toner used in this embodiment was measured using a Coulter counter manufactured by Coulter Co., Ltd.
0 is used.

In the above configuration, in this embodiment, a structure like a boundary line appears on the image surface on the transfer body, having an appropriate gloss similar to that of a silver halide photographic paper photograph as follows. Thus, a color image with good graininess can be formed.

That is, in the color image forming apparatus 1 according to the present embodiment, as shown in FIG. 2, the yellow,
A transfer body on which an unfixed color image 21 made of three color toners of magenta and Sian and a transparent toner image 23 made of a transparent toner are formed, and an unfixed color image made of the color toner and the transparent toner is formed 12
Is transported to the fixing device 15 as shown in FIG.
By performing the pressure treatment, an unfixed color image including the color toner and the transparent toner is fixed on the transfer body 12.

In this embodiment, for example,
As shown in FIG. 3A, as a region where the development amount of the color toner changes abruptly, a plain background portion 20 where no color toner exists and an edge portion 22 of the color toner image 21
As shown in FIG. 3B, a transparent toner image 23 composed of a fixed amount of transparent toner is formed such that the portions 23a always overlap. For this reason, it is possible to form a color image with good graininess, having a moderate gloss similar to that of a silver halide photographic paper photograph, without the appearance of a structure like a boundary line on the image surface on the transfer body 12. Has become.

[0072]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings, but the present invention is not limited to these embodiments.

Example 1 Color Toner Developer The color toner developer used in the color image forming apparatus of Example 1 was A-Colo manufactured by Fuji Xerox Co., Ltd.
A cyan developer, a magenta developer, and a yellow developer for r were used. The average particle size of these color toners is 7 μm.
m.

The following resins were used as the binder resin for producing the color toner. Linear polyester obtained from terephthalic acid / bisphenol A ethylene oxide adduct / cyclohexanedimethanol as binder resin (Tg = 62)
° C, Mn = 4000, Mw = 35000, specific gravity 1.2)
Was pulverized by a jet mill, and then classified by an air classifier to produce a color toner having an average particle diameter d50 = 7 μm.

Transparent Toner A transparent resin was prepared by using the following binder resin obtained by changing the process for preparing Acolor toner resin, and having an average particle diameter of 11 μm. Linear polyester obtained from terephthalic acid / bisphenol A ethylene oxide adduct / cyclohexanedimethanol (Tg = 62 ° C., Mn = 2000, Mw = 1000)
0, specific gravity 1.2), pulverized with a jet mill, and then classified with an air classifier to obtain d50 = 11 μm.
m of transparent fine particles were produced.

This toner was mixed with the same carrier as the developer of the color toner to prepare a two-component developer.

Color Image Forming Apparatus The above-described color image forming apparatus shown in FIG. 2 was used as the image forming apparatus. In other words, Fuji Xerox's A
An apparatus modified from color630 was used.

With this device, the reflected light illuminated on the original 5 from the illumination 6 is read by the color CCD 7 and color-separated into three color signals of yellow, magenta and cyan by the image processing device 3 and the color toner of each pixel is read. After detecting the development amount, a transparent toner image was obtained by image processing. At this time, the pixel value of the peripheral area within a radius of 0.1 mm was checked, and the edge processing of the transparent toner image was performed using the Max operator that takes the maximum value. Further, as shown in FIG. 1, the transparent toner image 23 obtained by the image processing is subjected to a process of reducing the development amount toward the end of the color toner image 21 and further transferred onto the transfer body 12. The sum of the amount of color toner and the amount of transparent toner is 150% for chromatic color only at each point of the image
The amount of the transparent toner was adjusted as follows.

Light was output from the semiconductor laser 8 as an optical signal in order for each color. The optical signal was exposed through the optical system onto the photosensitive drum 10 charged in advance by the charger 16 to form an electrostatic latent image in which the image portion had a low potential. The developer containing the color toner is accommodated in the developing devices 11Y to 11C of the rotary developing device 11, the transparent toner is accommodated in the developing device 11T, and the developing is performed by applying a developing bias, and the powder toner is subjected to electrostatic force. The toner was attached to the electrostatic latent image on the photosensitive drum 10.

The transfer amount of the toner on the transfer body 12 is set to 5.0 (g / m ² ) for the color toner in the image portion having the area ratio of 100%, and 15.0 (g / m ² ) for the transparent toner. / M ² ).

The formed toner image is transferred to the transfer drum 13.
Each color was transferred to the transfer body 12 electrostatically adsorbed thereon by the electric field provided by the transfer corotron 15. This was repeated in the order of cyan, magenta, yellow, and transparent toner, and a powder toner image was obtained on the transfer body 21. Transfer body 12
Xerox's Never Tear paper was used. This is fixed at a temperature of 160 ° C. and a speed of 1
An image for evaluation was obtained by heating and fixing at 00 mm / s.

The evaluation manuscript is a photograph including a person,
A full-color evaluation image was created.

Example 2 An image was formed in the same manner as in Example 1 except that the process of reducing the development amount of the transparent toner image toward the edge of the color toner image was not performed.

Example 3 An image was formed in the same manner as in Example 2 except that the process of limiting the total amount of the color toner and the transparent toner transferred onto the transfer member to 150% was not performed. Created.

Example 4 In Example 1, when obtaining a transparent toner image, a radius of 0.
An image was created in the same manner as in Example 1 except that the pixel value of the peripheral region within 5 mm was examined, and the edge processing of the transparent toner image was performed using the Max operator that takes the maximum value.

Comparative Example 1 In Example 1, the processing for adding the transparent toner image to the sharply changing portion of the color toner image and outputting the same was not performed.
An image was formed in the same manner as in Example 1, except that the total amount of the developed toner was simply made constant.

Using the images created in Examples 1 to 4 and Comparative Example 1, the image quality was evaluated by visual evaluation. For 23 evaluators: Structural lines on the surface of the image are seen throughout the image, which is completely different from silver halide photographic paper photographs and is not preferred. 2. The structure line is partially seen and is annoying, which is not preferable unlike a silver halide photographic paper photograph. 3. 3. Structural lines are partially seen, but not bothersome, slightly closer to silver halide photographic paper photographs The structural lines were not visible at all, and they were classified into four categories, which are close to silver salt photographic paper photographs, and the average value was calculated. X when the average value is less than 2.5, o when 2.5 or more and less than 3.5,
The case of 3.5 or more was evaluated as ◎.

FIG. 5 is a table showing the results of evaluating the images created in the above Examples 1 to 4 and Comparative Example 1.

As is clear from the results shown in FIG.
It can be seen that Examples 1 to 4 according to the present invention have high evaluation of image quality overall, and particularly, Examples 1 and 2 have high evaluation of image quality.

[0090]

As described above, according to the present invention, it has the same good glossiness as a silver halide photographic paper photograph, and a structure like a boundary line appears on the image surface on the transfer body. It is possible to provide a color image forming apparatus capable of forming an uncolored image.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing a color image formed by a color image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a configuration diagram illustrating a color image forming apparatus according to an embodiment of the present invention.

FIG. 3 is a schematic sectional view showing a color image formed by the color image forming apparatus according to one embodiment of the present invention.

FIG. 4 is a schematic sectional view showing a color image formed by the color image forming apparatus according to one embodiment of the present invention.

FIG. 5 is a table showing evaluation results of the examples and the comparative examples of the present invention.

FIG. 6 is a schematic sectional view showing a color image formed by a conventional color image forming apparatus.

[Explanation of symbols]

12: transfer member, 21: color toner image portion, 22: image density change portion, 23: transparent toner image.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Satoshi Tsuda 430 Nakaicho, Ashigarakami-gun, Kanagawa Prefecture Green Tech Nakai Fuji Xerox Co., Ltd. F-term (reference) 2H030 AD01 AD12 AD16 BB36

Claims (5)

[Claims] An image carrier on which a plurality of toner images of different colors are formed based on image information of a color image, and an image carrier formed of transparent toner based on the image information of the color image. Image processing means for generating image information to be formed, and transparent toner image formation for forming an image with transparent toner on the image carrier or a different image carrier based on the image information generated by the image processing means Means, a transfer means for transferring a plurality of different toner images and a transparent toner image formed on the image carrier onto a transfer body directly or via an intermediate transfer body; and A fixing unit for fixing the toner image and the transparent toner image on a transfer body, wherein a transparent toner image made of a transparent toner is formed in an area where the color image is not formed. Both the portion in which the concentration of the color image is rapidly changed, the color image forming apparatus, and forming so as to partially overlap the transparent toner image formed of transparent toner. 2. The image processing means detects a portion where the density of a color image changes rapidly, and forms a transparent toner image made of transparent toner so as to overlap a portion where the density of the color image changes rapidly. The color image forming apparatus according to claim 1, wherein: 3. The image processing means detects a portion where the density of a color image changes rapidly, and sets the color image and a transparent toner image composed of a transparent toner so as to overlap by 0.1 mm or more. Claim 1 or 2
3. The color image forming apparatus according to 1. 4. The method according to claim 1, wherein the sum of the toner amount of the color image transferred onto the transfer member and the toner amount of the transparent toner image is set to be 150% or less of the maximum toner amount of the color image. The color image forming apparatus according to claim 1. 5. The image processing means detects a portion where the density of a color image changes abruptly, and comprises a transparent toner so as to overlap the portion where the density of the color image changes abruptly in an inclined state. 5. The color image forming apparatus according to claim 1, wherein the color image forming apparatus forms a transparent toner image.