JPH11334151A - Imaging system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an imaging system in which one imaging unit can be selected appropriately among a plurality of imaging units assigned to same color depending on the image quality and requirements for different image characteristics can be satisfied. SOLUTION: Process units 1a, 1b are assigned to cyan, process units 2a, 2b are assigned to magenta and process units 3a, 3b are assigned to yellow wherein two process units for same color have different mean grain size of toner, manufacturing method, material quality, and the like. Consequently, image characteristics suitable for high definition half-tone representation, for high density solid part representation, and the like, can be selected appropriately. An image developed on a photosensitive body 103 of each process unit 1a-3a is transferred temporarily to an intermediate transfer body 4. A color image on the intermediate transfer body 4 is transferred to a transfer roller 5 and fixed by means of a fixing unit 6 before a color image 15 formed finally on a recording sheet 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention belongs to the technical field of an image forming apparatus for forming an image on a recording medium, such as an electrophotographic apparatus using toner and an ink jet printer using ink.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus such as an electrophotographic apparatus or an ink jet printer, a plurality of image forming units corresponding to, for example, four colors of black, yellow, cyan, and magenta are formed in order to form a color image. Equipped
Generally, the entire image forming apparatus is configured to output a specific color. For example, an electrophotographic apparatus is provided with a plurality of developing processes capable of forming an image using toner of each color, and an inkjet printer is configured to include a plurality of inkjet heads capable of outputting ink of each color. It is common to use

[0003] The pigment or the like in the toner or the ink is set to an optimum average particle size and an optimum material for each specific color, and then, under appropriate conditions for obtaining good image quality. A color image is formed below.

[0004]

In the above-described conventional image forming apparatus, there are various requirements for image quality when forming an image. For example, image quality with different characteristics must be formed depending on the situation, for example, when there are many solid portions and a high density is required, or when there are many fine and high-definition halftone expressions.

On the other hand, as described above, a specific type of toner or ink which has the greatest influence on image quality is used for a specific color. However, when the emphasis is placed on the expression of the solid portion and when the emphasis is placed on the expression of the halftone, the characteristics required for the toner and the ink are different, so that it is difficult to appropriately select the toner and the ink.
To give a specific example, it is better to increase the average particle diameter of the toner or the like in order to increase the image density and appropriately express the solid portion, and conversely, in order to express the halftone with high accuracy, It is better to reduce the average particle size of the toner and the like. However, as described above, a toner having a different average particle size for a specific color cannot be used, and the same applies to the material and the manufacturing method.

Accordingly, the present invention has been made in view of such a problem, and according to the image quality of an image to be formed,
It is an object of the present invention to provide an image forming apparatus such as an electrophotographic apparatus and an ink jet printer which can form an image using an image forming unit using an appropriate toner, ink or the like for each color.

[0007]

According to a first aspect of the present invention, there is provided an image forming apparatus including a plurality of image forming units. At least two or more image forming units having different characteristics are allocated, and among the two or more image forming units, one image forming unit selected corresponding to an image part to be formed forms the image part. And

According to the present invention, two or more image forming units are assigned to a specific color of an image to be formed, and all have different image characteristics. By paying attention to a certain image portion, one image unit most suitable for image expression such as solid or halftone reproduction is selected, and an image of the image portion is formed. Therefore, when expressing a specific color of a color image, an image can be formed while satisfying both contradictory characteristics, and a high-quality image can be formed by various image expressions.

According to a second aspect of the present invention, in the image forming apparatus of the first aspect, the substantially same colors are
The color is characterized in that the color difference is 30 or less in a Lab space in which lightness is expressed by the L axis and saturation and hue are expressed by the a axis and the b axis.

According to the present invention, two or more image forming units are allocated to colors determined to be the same color in the Lab space defining objective color perception in an image to be formed. With the same operation as described above, different image characteristics can be handled, and high-quality image formation can be performed with various image expressions.

According to a third aspect of the present invention, in the image forming apparatus according to the first or second aspect, the image forming apparatus is an electrophotographic apparatus.

According to the present invention, in an electrophotographic apparatus, a plurality of processes can be selectively used for the same color, for example, by using toners having different characteristics, and a high-quality image can be displayed in various image expressions. It can be formed using a photograph.

According to a fourth aspect of the present invention, in the image forming apparatus according to the first or second aspect, the image forming apparatus is an ink jet printer.

According to the present invention, in an ink jet printer, a plurality of ink jet heads can be selectively used for the same color by using inks having different characteristics, and a high quality image can be formed by various image expressions. It can be formed by a printer.

According to a fifth aspect of the present invention, in the image forming apparatus of the third aspect, the two or more image forming units use toners having different average particle diameters.

According to the present invention, in the electrophotographic apparatus, the toners used by a plurality of image forming units for the same color have different average particle diameters. Therefore, when it is desired to form an image with a large solid portion and a high density for a specific color, use an image forming unit having a large average particle diameter of the toner, and to form an image expressing a halftone with high definition. Accordingly, an image forming unit having a small average particle diameter of the toner can be used, and an image capable of selectively expressing various characteristics can be formed.

According to a sixth aspect of the present invention, in the image forming apparatus of the third aspect, the two or more image forming units use toners manufactured by different methods.

According to the present invention, in the electrophotographic apparatus, the toners used by a plurality of image forming units for the same color have different manufacturing methods. Therefore, when it is desired to form a high-density image with a large amount of solid portion for a specific color, for example, use an image forming unit using a pulverized toner having a large particle size and an uneven shape, and a high definition halftone. When it is desired to form an expressed image, an image forming unit using a polymerized toner having a small particle size and a spherical shape can be used, and an image capable of selectively expressing various characteristics can be formed.

According to a seventh aspect of the present invention, in the image forming apparatus of the third aspect, the two or more image forming units use toners of different materials.

According to the present invention, in the electrophotographic apparatus, toners used by a plurality of image forming units for the same color have different materials. Therefore, for a specific color, for example, by changing the content of various mixtures such as a charge auxiliary agent in the toner for each image forming unit,
By using an appropriate image forming unit according to the image characteristics, it is possible to form an image capable of selectively expressing various characteristics.

According to an eighth aspect of the present invention, in the image forming apparatus according to the fourth aspect, the two or more image forming units use inks containing coloring agents having different average particle diameters. Features.

According to the present invention, in the ink jet printer, the inks used for a plurality of ink jet heads for the same color have different average particle sizes of the colorants. Therefore, if you want to form a high density image with a large solid portion for a specific color, use an inkjet head with a large average particle size of the colorant in the ink to form an image that expresses halftones with high definition. When desired, an ink jet head having a small average particle size of the colorant in the ink can be used, and an image capable of selectively expressing various characteristics can be formed.

According to a ninth aspect of the present invention, in the image forming apparatus of the fourth aspect, the two or more image forming units use inks containing colorants of different materials. I do.

According to the present invention, in the ink jet printer, the ink used for a plurality of ink jet heads for the same color has different colorant materials. Therefore, for a specific color, a variety of characteristics can be selectively selected by changing the type of a pigment or the like as a colorant for each ink jet head and using an appropriate ink jet head according to image characteristics. Thus, it is possible to form an image that can be expressed.

According to a tenth aspect of the present invention, in the image forming apparatus of the eighth or ninth aspect, the ink is a hot melt ink.

According to the present invention, a plurality of ink jet heads having different average particle diameters and materials of the colorant of the hot melt ink can be selectively used for the same color. Thus, high-quality images can be formed with various image expressions.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings.

First Embodiment First, as a first embodiment of the present invention, an embodiment in which the present invention is applied to an electrophotographic apparatus that forms an image using toner will be described.

FIG. 1 is a diagram showing the overall configuration of the electrophotographic apparatus according to the first embodiment. The electrophotographic apparatus shown in FIG. 1 is configured by providing two process units each for the same color of cyan, magenta, and yellow.

Here, when determining that the colors are the same, for example, a Lab space that defines objective perception of color can be used. That is, the color difference in the Lab space, which is a coordinate system that expresses lightness by the L axis and chroma and hue by the a / b axes, corresponds to the perceived color difference. In the first embodiment, a case where the color difference in the Lab space is, for example, 30 or less may be determined to be “the same color”.

As shown in FIG. 1, the electrophotographic apparatus according to the first embodiment has a process unit 1a, 1b for cyan.
And the process units 2a and 2b for magenta and the process units 3a and 3b for yellow
And a transfer roller 5, a fixing unit 6, and a recording sheet 7. In addition, two black process units (not shown) may be arranged around the intermediate transfer member 4.

The process units 1a to 3b function as image forming units.
, A developing roller 102, a photoconductor 103, an optical scanner 104, and a charger 105. Since the process units 1b, 2a, 2b, 3a, and 3b have the same structure, the process unit 1a will be described as a representative.

In the process unit 1a, the photosensitive member 103 is uniformly charged by the charger 105, and the photosensitive drum 103 is irradiated with laser light or the like in accordance with the image data to be formed by the optical scanner 104, and is statically charged. An electrostatic latent image is formed. On the other hand, a cyan toner 106 having predetermined characteristics is supplied from a toner storage chamber (not shown) to a charger 105 by a supply roller 101 and adheres to the surface of a developing roller 102. The toner 106 is adhered and developed.

The developed cyan toner image on the photosensitive member 103 is transferred to the intermediate transfer member 4. This intermediate transfer member 4
Is a medium made of a material such as polyimide, which is rotated and transferred by two rollers in the form of a belt, sequentially contacts and rotates with the photoconductor 103 of each of the process units 1a to 3b, and the developed toner image is transferred once. is there. Then, after the respective color toner images are transferred to the intermediate transfer member 4, the toner images are subsequently transferred to the recording paper 7 by the transfer roller 5. Thereafter, the recording paper 7 to which the color image has been transferred is pressed while being heated by the fixing unit 6, and the color image is fixed on the recording paper 7.

The process units 1a and 1b for cyan use cyan toners 106 having different characteristics such as average particle diameter and material, respectively, as described later. The characteristics are different. Similarly, the magenta process units 2a and 2b and the yellow process unit 3
a and 3b form a magenta image and a yellow image having different image characteristics while using the same color toner having different characteristics.

Accordingly, the color image transferred to the intermediate transfer member 4 and then transferred to the recording paper 7 can express different characteristics for each color. For example, for the same color, an image portion to be expressed with high density such as a solid portion and an image portion to be expressed with high definition such as halftone can be expressed by different image characteristics using different process units. In the first embodiment, for example, which one of the process units 1a and 1b is used for a cyan image is determined by a CPU (not shown) or appropriately set by a user using input means (not shown). Method can be selected.

Next, a description will be given of a specific example of the difference in the characteristics given to the toner used to form images having different image characteristics in the two process units 1a and 1b for cyan. In the following description, the situation is the same for the magenta process units 2a and 2b and the yellow process units 3a and 3b, and therefore, the description thereof is omitted, and the process units 1a and 1a for cyan are representatively described. 1b will be described.

First, the average particle size of the toner used in each of the process units 1a and 1b can be changed. That is, as the average particle size of the toner particles changes, the resolution varies, and the degree of the influence of electrostatic force acting on the toner particles, adhesion force due to van der Waals force, air resistance, gravity, etc. is relatively increased. As a result, the fluidity and the mixing property of the toner also vary, which greatly affects the image quality. When a toner having a small average particle size is used, the fluidity and image density are reduced, but the resolution is improved, which is suitable for halftone reproduction and fine-grained expression. On the other hand, when a toner having a large average particle size is used, the resolution is reduced, but a sufficient image density is obtained, which is suitable for expressing a solid portion.

Therefore, for example, in the process unit 1a, a toner having a small average particle size is used, and the process unit 1a is used.
In b, by using a toner having a large average particle size and selecting the toner according to the image portion to be formed, it is possible to form an image while achieving conflicting image quality. The average particle size of the toner is, for example, 5
What is necessary is just to set it to about 10-10 micro | micron | mu, and to make the larger one about 10-20 micron.

Second, the method of manufacturing the toner used in each of the process units 1a and 1b can be changed. That is, the toner is roughly classified into two types, depending on the manufacturing method, a pulverized toner obtained by mixing various materials and then mechanically pulverizing, and a polymerized toner obtained by polymerizing various materials by a chemical reaction. The average particle size of the pulverized toner is relatively large and the shape of the toner particles is irregular, whereas the average particle size of the polymerized toner is small and the shape of the toner particles is close to spherical. Therefore, when the polymerized toner is used, the image density is reduced, but the resolution is improved. When the pulverized toner is used, the resolution is reduced, but a sufficient image density is obtained.

Therefore, for example, by using the polymerized toner in the process unit 1a and using the pulverized toner in the process unit 1b and selecting according to the image portion to be formed, conflicting image quality can be achieved. An image can be formed.

Third, the material of the toner used in each of the process units 1a and 1b can be changed. That is, since the constituent components of the toner include a binder resin, a colorant, a charge auxiliary agent, an external additive, and the like, the image characteristics can be changed by changing the material, the mixing ratio, and the like. For example, by adjusting the content of the charge auxiliary, the amount of charge of the toner particles can be controlled to be large or small. The charge amount of the toner particles affects the attraction to the developing roller and the like, and if the charge amount of the toner particles is increased, the image density is reduced, but the resolution is improved, and the charge amount of the toner particles is reduced. Then, although the resolution decreases,
The image density increases.

Therefore, for example, the content of the charge auxiliary agent in the toner is appropriately adjusted so that the charge amount of the toner particles is increased in the process unit 1a and the charge amount of the toner particles is decreased in the process unit 1b. If the image quality is adjusted according to the image portion to be formed, an image can be formed with both conflicting image qualities.

In the first embodiment described above, the case where the system in which the transfer is performed from the plurality of process units 1a to 3b arranged in parallel to the intermediate transfer member 4 at one time is used has been described. Alternatively, a plurality of process units 1a to 3b may perform separate transfer, respectively, and form an image through all the processes in order.

Further, in the above description, a configuration in which two process units are provided for each same color has been described. However, the present invention is not limited to this. Further, process units corresponding to different image characteristics for the same color are further provided. A large number may be provided.

(Second Embodiment) Next, as a second embodiment of the present invention, an embodiment in which the present invention is applied to an ink jet printer that forms an image using ink will be described.

FIG. 2 is a diagram showing the overall configuration of an ink jet printer according to the second embodiment. The inkjet printer shown in FIG. 2 is configured by providing two inkjet heads for each of the same color of cyan, magenta, and yellow. The meaning of the “same color” may be considered in the same manner as in the first embodiment.

As shown in FIG. 2, the ink jet printer according to the second embodiment includes an ink jet head 10 for black, ink jets 11a and 11b for cyan,
Magenta inkjet heads 12a and 12b,
Inkjet heads 13a and 13b for yellow,
Intermediate transfer belt 14, drive roller 15, tension roller 16, guide plate 17, cooling fin 18,
, A transfer unit 19, a cleaning roller 20, a paper heater 21, and a recording sheet 22.

The ink-jet heads 10 to 13b function as image forming units, and pressurize ink of each color to eject ink droplets from nozzles to land on predetermined positions of the intermediate transfer belt 14.

The intermediate transfer belt 14 is driven to rotate in a direction indicated by an arrow in FIG. 2 by a driving roller 15 and guides ink droplets from each of the inkjet heads 10 to 13b while maintaining a constant tension by the tension roller 15. It is transported along the plate 17. As a result, a four-color image is transferred to the intermediate transfer belt 14. The landing of the ink droplets by each of the inkjet heads 10 to 13b is performed while being heated, so that the cooling is performed by the cooling fins 18.

The color image once transferred onto the intermediate transfer belt 14 is pressed by the transfer unit 19 while heating the recording paper 22 conveyed through the heating by the paper heater 21.
A color image is formed. Thereafter, the ink adhered to the intermediate transfer belt 14 by the cleaning roller 20 is removed, and the intermediate transfer belt 14 is subjected to another transfer.

As will be described later, the ink jet heads 11a and 11b for cyan use inks containing cyan colorants having different characteristics such as average particle diameter and material, respectively. Have different image characteristics. Similarly, magenta inkjet heads 12a, 12a
b, yellow inkjet heads 13a, 13b
Is to form a magenta image and a yellow image having different image characteristics while using inks containing the same colorant having different characteristics.

Therefore, the image is transferred to the intermediate transfer belt 14 and
Thereafter, the color image formed on the recording paper 7 can express different characteristics for each color, as in the first embodiment.
For the same color, an image portion to be expressed with high density such as a solid portion and an image portion to be expressed with high definition such as halftone can be expressed by different image characteristics using different ink jet heads. Further, the selection of the ink jet to be used for the same color is the same as in the first embodiment.
The judgment of the CPU not shown or the setting of the user, etc.
It is performed by an appropriate method.

Next, a description will be given of a specific example of the difference between the characteristics applied to the inks used to form images having different image characteristics between the two inkjet heads 11a and 11b for cyan. In the following description, the situation is the same for the magenta inkjet heads 12a and 12b and the yellow inkjet heads 13a and 13b.
11b will be described.

First, each of the ink jet heads 11a,
The size of the average particle size of the colorant contained in the ink used in 11b can be changed. That is, the ink contains a colorant such as a pigment and a solvent for dissolving the colorant as main components, and image characteristics mainly depend on the characteristics of the colorant. By changing the average particle size of the colorant, the resolution is changed, and the viscosity of ink, the surface tension, the speed at which ink droplets are ejected from the nozzles are affected, and the image quality is greatly affected. When an ink containing a colorant having a small average particle size is used, the image density is reduced, but the resolution is improved, and it is suitable for reproducing halftones and expressing finely. On the other hand, when an ink containing a colorant having a large average particle size is used, the resolution is reduced, but a sufficient image density is obtained, and the image is suitable for expressing a solid portion.

Therefore, for example, the ink jet head 1
1a uses an ink containing a colorant having a small average particle size, and the inkjet head 11b uses an ink containing a colorant with a large average particle size, so that the ink is selected according to the image portion to be formed. In this case, an image can be formed while achieving conflicting image quality. The colorant has an average particle size of the inkjet heads 11a, 1
It is necessary to set the nozzle diameter sufficiently smaller than 1b.

Second, each of the ink jet heads 11a,
The material of the colorant contained in the ink used in 1b can be changed. That is, there are a great number of types of pigments and the like for the same color, and the image quality is slightly different from each other. For example, by using coloring agents having different light transmission amounts, the transparency of the ink can be changed. An ink containing a colorant having a large light transmission amount has high transparency, and the image density is reduced, but the resolution is improved. On the other hand, an ink containing a colorant having a small light transmission amount has low transparency and resolution is reduced,
The image density increases.

Therefore, for example, the ink jet head 1
In 1a, an ink containing a colorant having a high light transmission amount is used, and in an ink jet head 11b, an ink containing a colorant having a low light transmission amount is used, and the ink is selected according to an image portion to be formed. By doing so, it is possible to form an image while achieving conflicting image quality.

In the second embodiment described above, the present invention can be applied to a case where a solid hot-melt type ink is used by using a hot-melt type ink-jet head which is heated and melted when used. .

Further, in the above description, the case of using the method of performing the transfer from the plurality of ink jet heads 10 to 13b arranged in parallel to the intermediate transfer belt 14 has been described. However, each of the ink jet heads 10 to 13b is directly applied to the recording paper. A method of ejecting ink droplets may be used.

In the above description, a configuration in which two ink jet heads are provided for each same color has been described. However, the present invention is not limited to this, and ink jet heads corresponding to different image characteristics for the same color are further provided. A large number may be provided.

[0062]

According to the first aspect of the present invention, two or more image forming units having different image characteristics are assigned to a specific color, and a specific image portion is formed by selecting one image unit. Therefore, it is possible to form an image while satisfying both contradictory characteristics, and to form a high-quality image with various image expressions.

According to the second aspect of the present invention, two or more image forming units are assigned to colors determined to be the same color in the Lab space. High-quality image formation can be performed with various image expressions.

According to the third aspect of the present invention, in the electrophotographic apparatus, a plurality of processes having different toner characteristics and the like can be selectively used for the same color. Image formation can be performed using electrophotography.

According to the fourth aspect of the present invention, in the ink jet printer, a plurality of ink jet heads having different ink characteristics and the like can be selectively used for the same color. Image formation can be performed by an inkjet printer.

According to the fifth aspect of the present invention, since the image forming units using toners having different average particle diameters are assigned to the same color, it is possible to form both a high-density image and a high-definition image. Thus, it is possible to form an image by electrophotography capable of selectively expressing various characteristics.

According to the sixth aspect of the present invention, since the image forming units using different toners for the same color are allocated to the same color, both a high-density image and a high-definition image can be formed. In addition, it is possible to form an image by electrophotography capable of selectively expressing various characteristics.

According to the seventh aspect of the present invention, since the image forming units using toners of different materials are assigned to the same color, both a high-density image and a high-definition image can be formed. It is possible to form an image by electrophotography that can selectively express various characteristics.

According to the eighth aspect of the present invention, since an ink jet head using an ink containing a colorant having a different average particle diameter is allocated to the same color, both a high-density image and a high-definition image can be obtained. It is possible to form an image using an inkjet printer that can selectively express various characteristics.

According to the ninth aspect of the present invention, an ink jet head using an ink containing a colorant of a different material is assigned to the same color, so that both a high-density image and a high-definition image are formed. Image formation using an ink jet printer capable of selectively expressing various characteristics.

According to the tenth aspect of the present invention, even when hot-melt ink using hot-melt ink is used, high-quality images can be formed with various image expressions.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of an electrophotographic apparatus according to a first embodiment of the present invention.

FIG. 2 is an overall configuration diagram of an inkjet printer according to a second embodiment of the present invention.

[Explanation of symbols]

 1a, 1b: Process unit for cyan 2a, 2b: Process unit for magenta 3a, 3b: Process unit for yellow 4 ... Intermediate transfer member 5 ... Transfer roller 6 ... Fixing unit 7, 22 ... Recording paper 10 ... Black inkjet head 11a .., 11b... Inkjet heads for cyan 12a, 12b... Inkjet heads for magenta 13a, 13b... Cleaning roller 21: Paper heater

Continued on the front page (51) Int.Cl. ⁶ Identification code FI G03G 21/14 G03G 21/00 372

Claims (10)

[Claims] An image forming apparatus including a plurality of image forming units, wherein at least two or more image forming units having different image characteristics are assigned to substantially the same color, and among the two or more image forming units, An image forming apparatus, wherein one image forming unit selected corresponding to an image portion to be formed forms the image portion. 2. The substantially identical color is a color having a color difference of 30 or less in a Lab space in which lightness is expressed by an L-axis and saturation and hue are expressed by an a-axis and a b-axis. The image forming apparatus according to claim 1. 3. The image forming apparatus according to claim 1, wherein the image forming apparatus is an electrophotographic apparatus. 4. The image forming apparatus according to claim 1, wherein the image forming apparatus is an ink jet printer. 5. The image forming apparatus according to claim 3, wherein the two or more image forming units use toners having different average particle diameters. 6. The image forming apparatus according to claim 3, wherein the two or more image forming units use toners manufactured by different methods. 7. The image forming apparatus according to claim 3, wherein the two or more image forming units use different toners. 8. The image forming apparatus according to claim 4, wherein the two or more image forming units use inks containing colorants having different average particle diameters. 9. The image forming apparatus according to claim 4, wherein the two or more image forming units use ink containing a colorant having a different material. 10. The image forming apparatus according to claim 8, wherein the ink is a hot melt ink.