JP4075547B2 - Image forming method and image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image forming method and an image forming apparatus for forming an image by transferring and fixing an image made of toner on an image support material, and in particular, can obtain a high quality image comparable to the image quality of a silver salt photograph. The present invention relates to a possible image forming method and an apparatus therefor.
[0002]
[Prior art]
[Patent Document 1]
JP 7-319316 A
[0003]
Conventionally, as an image forming method for forming a full-color image with color toner on an image support, the glossiness of the image support is Gp (%), and an image portion formed by transferring and fixing the toner on the support is used. When the glossy part is Gt (%),
1 / 3Gp ≦ Gt ≦ (4 / 5Gp + 15)
Has been proposed (see Patent Document 1). In this image forming method, the temperature of the fixing roller and the fixing linear velocity are changed as means for establishing the relationship.
[0004]
According to this image forming method, by suppressing the difference in glossiness between the non-image area and the image area, an image that does not give a sense of incongruity to the image viewing side is formed, and glossiness that matches the glossiness of the recording paper itself. Thus, an effect that does not hinder the purpose and function of the recording paper is obtained.
[0005]
However, although this image forming method suppresses the difference in glossiness between the image portion and the non-image portion, for example, even when recording paper having a Gp of 90% is used, as shown in FIG. Since the gloss range Gp allows a wide range from a value of slightly less than 30% to a value close to 90%, the resulting full-color image has a sense of incongruity and is inferior in comparison with the image quality of silver photographs. Further, the obtained full-color image has a difference in level between the image portion and the non-image portion even with the naked eye, and this is also inferior to the image quality of silver photographs.
[0006]
[Problems to be solved by the invention]
The present invention has been made in view of the circumstances as described above, and its main object is to form an image capable of obtaining a high-quality image that does not feel uncomfortable with the image quality of a silver salt photograph. It is to provide a method and apparatus thereof.
[0007]
[Means for Solving the Problems]
As a result of diligent research to achieve the above object, the present inventor has made possible the difference between the glossiness of the surface (non-image portion) of the image support material and the glossiness of the image portion formed on the image support material. It was found that the above-mentioned object can be achieved by reducing as much as possible and also reducing the level difference between the image portion and the non-image portion as much as possible, and the present invention has been completed.
[0008]
The image forming method of the present invention is an image forming method in which an image made of toner is transferred and fixed to an image support material to form an image. The image support material has a surface glossiness of Gp (%), and the image support material. Gp ≧ 90, Gt ≧ 90, and Gp ≦ Gt are established when the glossiness of the image portion formed on the surface is Gt (%), and the level difference between the image portion and the surface of the image support material is When h is set, an image that satisfies the relationship of h ≦ 3 μm is formed.
[0009]
The image forming apparatus according to the present invention is an image forming apparatus that forms an image by transferring and fixing an image made of toner onto an image support material. A belt, a heating and pressurizing unit that heat-presses the image support material after the toner image has been transferred to the surface of the fixing belt, and a state of being in close contact with the surface of the fixing belt by the heating and pressing unit At least a belt fixing device having a cooling means for cooling the image support material conveyed by the apparatus, the glossiness of the surface of the image support material is Gp (%), and the glossiness of the image portion formed on the image support material When Gt (%) is satisfied, the relationship of Gp ≧ 90, Gt ≧ 90 and Gp ≦ Gt is established, and when the level difference between the image portion and the image support material surface is h, h ≦ 3 μm Images that hold the relationship It is characterized in that the effect formation.
[0010]
In both the inventions, the glossiness Gp (%) and Gt (%) are measured in accordance with JIS Z8741 Method 2 (75 ° specular gloss). For example, a gloss meter (Murakami Color Research Laboratory) : MODEL GM-26D FOR75 °). The glossiness Gp of the image support material is measured at a non-image portion after image formation. On the other hand, the level difference h is obtained by measuring the height (thickness) of the image portion from the surface of the image support material using a laser focus displacement meter (manufactured by KEYENCE: LT-8010).
[0011]
In both the inventions, an image made of toner (toner image) is an image composed of toner as a developer, and usually uses one color (except black toner) or multiple color toners. Although it is a color image to be formed, it may be a black image. The image support material is not particularly limited as long as it basically satisfies the condition of the glossiness Gp and can transfer and fix the toner image.
[0012]
According to such an image forming method and apparatus of the present invention, the difference in glossiness between the image portion and the non-image portion and the level difference between the non-image portion of the image portion. But Since an extremely small number of images can be obtained, it is possible to form an image having an image quality that is not sensuously uncomfortable with the image quality of a silver salt photograph. In particular, such an image is obtained by using the belt fixing device described above as a fixing device. Than It can be obtained easily and reliably.
[0013]
In the image forming apparatus of the present invention, a fixing device other than the belt fixing device is provided as the fixing device, and at least fixing by the other fixing device is performed and then fixing by the belt fixing device is performed. It is good to configure. In this case, it is possible to more easily obtain the gloss difference and level difference images. In addition, it is possible to cope with only fixing by another fixing device when an image having a general level of image quality is formed.
[0014]
Furthermore, in both the image forming method and the apparatus of the present invention, a recording sheet in which an image receiving layer made of a polyolefin resin is formed on at least one surface of a sheet-like substrate may be used as the image support material. In this case, it is possible to form an image in which an image made of toner is embedded in the image receiving layer portion, so that it is possible to more easily and reliably obtain the above-described difference in glossiness and level difference.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1
FIG. 1 shows a color image forming apparatus used in an image forming method according to Embodiment 1 of the present invention.
[0016]
The color image forming apparatus includes an image forming system 2 using an intermediate transfer system, a paper feeding unit 3 for supplying a recording sheet P, a first fixing device 4, a second fixing device 5, and an image. A processing unit 6, a control unit 7 and the like are provided. Further, an original reading device 8, a digital still camera (DSC) data input unit 9, an operation display unit 100, and the like are disposed outside the housing 1.
[0017]
The image forming system 2 includes four image forming units 10Y, 10M, 10C, and 10K that exclusively form four color toner images of yellow (Y), magenta (M), cyan (C), and black (K). It is mainly composed of an intermediate transfer belt 20 that carries a toner image formed by two image forming units 10 (Y, M, C, K) and conveys it to a transfer position to a recording sheet P.
[0018]
Each of the image forming units 10 basically has a photosensitive drum 11 having an organic photosensitive layer or the like formed on the surface thereof and rotating in the direction of arrow A. The photosensitive drum 11 is subjected to the following electrophotographic process. An unfixed toner image is formed. That is, first, the surface of the rotating photosensitive drum 11 is uniformly charged by a charging device 12 such as a roll type, and then the laser beam LB based on the image forming data signal is scanned and exposed from the exposure device 13 to the charged surface. As a result, an electrostatic latent image is formed. Next, the latent image is developed with the toner component of the developer supplied from the developing device 14 and is visualized as a toner image of a predetermined color. Thus, the toner image formed by each image forming unit 10 is electrostatically primary-transferred to the intermediate transfer belt 20 passing between each photosensitive drum 11 and the primary transfer roll 15. Yes. After the transfer, the surface of the photosensitive drum 11 is cleaned by a drum cleaning device 16 and then discharged by a lamp-type discharging device 17. Reference numeral 18 (Y, M, C, K) in the figure denotes a toner cartridge in which toner to be supplied to each developing device 14 is stored.
[0019]
The intermediate transfer belt 20 is an endless belt having a two-layer structure in which a surface layer such as silicone rubber is laminated on a belt base material such as a polyimide film containing a conductive material and the like and adjusted in volume resistivity. The intermediate transfer belt 20 is stretched between a drive roll 21, a backup roll 22 of a secondary transfer section, and a plurality of driven rolls 23, 24,. The unit 10 is disposed in contact with the photosensitive drum 11 and rotates in the direction of arrow B.
[0020]
The paper feed unit 3 has a plurality of paper feed cassettes 31a and 31b for stacking and storing a plurality of recording sheets P by size. The sheet feeding unit 3 feeds recording sheets P from the sheet feeding cassette 31 one by one by a sheet feeding device 32, and passes a pair of registration rolls through a sheet feeding conveyance path R1 constituted by a plurality of conveyance roll pairs, guide members, and the like. Then, the recording sheet P is fed to the secondary transfer position by the registration roller pair 33 in accordance with the secondary transfer timing.
[0021]
The recording sheet P is not particularly limited as long as it can be conveyed through the image forming apparatus and can transfer and fix the toner image. As the recording sheet P, plain paper P1 or coated paper having a prescribed size such as A4 plate or B5 plate is usually used. When performing image formation (output) in a photographic print mode, which will be described later, as shown in FIG. 2, a sheet-like substrate (plain paper, coated paper, etc.) 71 is made of a polyolefin resin such as polyester on at least one side. Photographic recording paper P2 having a transparent image receiving layer 72 formed to a thickness of about 5 to 20 μm is used. Such a recording sheet P2 for photographic print has a uniform gloss feeling over the entire surface on which the image receiving layer 72 is formed.
[0022]
The toner image transferred to the intermediate transfer belt 20 is conveyed to a secondary transfer position between the belt 20 and the secondary transfer roll 25 disposed opposite to the backup roll 22 while being carried on the belt 20. Electrostatically with respect to a recording sheet P of a predetermined size (here, the above-described plain paper P1 is supplied) conveyed and supplied from the paper supply cassette 31 by the paper supply unit 3 to the secondary transfer position. Secondary transferred. The surface of the intermediate transfer belt 20 after the secondary transfer is cleaned by a belt cleaning device 26.
[0023]
In this image forming apparatus, four color toner images respectively formed by the four image forming units 10 (Y, M, C, K) are sequentially transferred onto the intermediate transfer belt 20, and then the multiple toner images are transferred to the recording sheet P. It is possible to form a full-color image by performing secondary transfer collectively. Further, only a part of the four image forming units 10 (Y, M, C, K), for example, the black image forming unit 10K is operated to form a black toner image, and the intermediate transfer belt. A monochrome image such as a black-and-white image can be formed by transferring it onto the recording sheet P via 20, and a multicolor image in which two to three color toner images are mixed can also be formed.
[0024]
The first fixing device 4 basically has a heating roll 41 and a pressure belt 42 arranged in pressure contact with each other. The heating roll 41 is formed by coating a metal cylindrical roll made of aluminum or the like with an elastic layer (for example, a silicone rubber layer) and a release layer (for example, a PFA tube), and arranging a heating source such as a halogen lamp inside the roll. It is. The pressure belt 42 is formed by forming a release layer (for example, a PFA tube) on a belt base material made of a polyimide film or the like. In addition, a pressure pad that presses the belt against the heating roll 41 to form a nip is disposed inside the pressure belt 42.
[0025]
The second fixing device 5 is disposed at a downstream side of the first fixing device 4 in the recording sheet conveyance direction, and is particularly effective for fixing a belt with high gloss and photographic image quality. Device. The second fixing device 5 basically includes a heating roll 51 rotating in the direction of arrow C, a peeling roll 52, a steering roll 53, a fixing belt 54 wound around each of the rolls 51 to 53, A pressure roll 55 that presses the fixing belt 54 against the heating roll 51 to form a nip, a cooler 56 that cools a portion of the fixing belt 54 downstream of the nip, and the like are provided.
[0026]
The heating roll 51 is formed by coating an elastic layer (for example, a silicone rubber layer) on a metal cylindrical roll having high thermal conductivity and arranging a heating source such as a halogen lamp inside the roll. The peeling roll 52 is for peeling the recording sheet P from the fixing belt 54 by the rigidity of the sheet itself. The outer dimension of the roll 52 is determined by the adhesion between the fixing belt 54 and the recording sheet P and the winding angle of the fixing belt 54 around the peeling roll 52. The steering roll 53 is for adjusting the traveling direction of the fixing belt 54 in order to prevent the end of the belt from being damaged due to the offset running that occurs when the fixing belt 54 rotates. Specifically, one shaft of the roll 53 is fixed in position, and the other shaft is displaced so as to be inclined with respect to the axis of the heating roll 51 by a displacement mechanism (not shown). The pressure roll 55 is formed by coating an elastic layer (for example, a silicone rubber layer) and a release layer (for example, a fluororesin tube such as PFA) on a metal cylindrical roll having high thermal conductivity, and a halogen lamp or the like inside the roll. The heating source is arranged.
[0027]
The fixing belt 54 is formed by coating a thermosetting polyimide endless film (75 μm or more) with a surface layer (30 μm or more) such as silicone rubber having a smooth surface. The cooler 56 is for cooling the recording sheet P that is actually in close contact with the fixing belt 54. The cooler 56 is disposed in the inner peripheral surface area of the fixing belt 54 between the heating roll 51 and the peeling roll 52, and contacts the inner peripheral surface to absorb the heat of the belt 54. It consists of a plate.
[0028]
Further, between the first fixing device 4 and the second fixing device 5, the second fixing conveyance path R2 for conveying the recording sheet P after the completion of the first fixing to the second fixing device 5 and the recording sheet P are provided. A discharge conveyance path R3 is provided which branches in the middle of the second fixing conveyance path R2 and is discharged and conveyed outside the housing 1. Further, there is provided a reverse retransmission path R4 for retransmitting the recording sheet P discharged on the discharge conveyance path R3 to the paper feed conveyance path R1 with the front and back surfaces thereof reversed. The reverse retransmission path R4 is provided in a state where it is branched in the middle of the discharge transport path R3 and joins at a position before the pair of registration rolls 33 on the paper feed transport path R1. Each of the transport paths R2 to R4 includes a pair of transport rolls and a guide member. Transfer direction switching for feeding the recording sheet P to the predetermined transfer path side at the branch point of the second fixing transfer path R2 and the discharge transfer path R3 and the branch point of the discharge transfer path R3 and the reverse retransmission path R4. Gates 35 and 36 are provided, respectively. In the figure, reference numerals 37 and 38 are discharge roll pairs, and 39 is a discharge tray.
[0029]
The recording sheet P on which the toner image is secondarily transferred is sent to the first fixing device 4 and is heated and pressed by passing through the nip between the heating roll 41 and the pressure belt 42. As a result, the toner image is fixed on the recording sheet P. The recording sheet P that has been subjected to the first fixing by the first fixing device 4 goes through one of the following three process patterns. One is transported to the second fixing device 5 through the second fixing transport path R2 by the guide of the transport direction switching gate 35, and second fixing is performed. The second is sent to the discharge conveyance path R3 side by the guide of the transfer direction switching gate 35 and discharged to the outside of the apparatus (discharge tray or the like) by the discharge roll pair 37. The third pattern is a process pattern for forming a double-sided image, and is retransmitted from the discharge conveyance path R3 to the sheet feeding conveyance path R1 through the reverse retransmission path R4 under the guidance of the conveyance direction switching gate 36. Image formation (secondary transfer of toner image) is performed.
[0030]
The second fixing by the second fixing device 5 is performed as follows. First, when the recording sheet P after the first fixing is fed into the second fixing device 5, the recording sheet P is heated and pressurized by passing through the nip between the fixing belt 54 and the pressure roll 55, and the nip After passing, the sheet is conveyed while being in close contact with the fixing belt 54. Subsequently, the recording sheet P in close contact with the fixing belt 54 is cooled to a predetermined temperature by the cooler 56, and then peeled off from the fixing belt 47 at a portion where the peeling roll 52 is located. As a result, the toner image fixed by the first fixing device is fixed again on the recording sheet P in a state in which the smooth surface of the fixing belt 54 is transferred to give a glossy feeling. The recording sheet P after the second fixing is discharged onto the discharge tray 39 by the discharge roll pair 38.
[0031]
The document reading device 8 illuminates a document to be copied with a light source, reads the reflected light of the image from the document with a CCD (charge coupled device) sensor, performs necessary image signal processing, and inputs it as image data. Is. Image data read by the document reading apparatus is transmitted to the image processing unit 6 through a transmission cable.
[0032]
The DSC data input unit 9 is for inputting data such as image data of a digital still camera via a memory medium or a communication means having various forms such as a card type and a stick type. The imaging data is image data obtained by imaging with DSC. The camera data input by the input unit 9 is sent to the image processing unit 6.
[0033]
The image processing unit 6 performs predetermined image processing (color conversion processing, resolution processing, scaling processing, processing / editing processing, etc.) on the image data sent from the document reading device 8 and the camera data sent from the DSC data input unit 9. ) And converted to image forming data, and then the image forming data is transmitted to the exposure device 13 in the image forming system 2.
[0034]
The control unit 7 controls the operation of the entire system of the image forming apparatus. The image forming system 2, the paper feeding unit 3, the first fixing device 4, the second fixing device 5, the image processing unit 6, and the image Necessary control signals are sent to the reader 8, the DSC data input unit 9, the operation display unit 100, and the like. The control unit 7 is composed of a microcomputer composed of a CPU, ROM, RAM, and the like. The control program stored in a memory such as a ROM and the contents of selection instruction information input from the operation display unit 100 are included in the control unit 7. The control operation is executed according to the above. A control program related to each operation described later is also stored in a memory such as a ROM.
[0035]
The operation display unit 100 includes an operation unit 110 provided with keys for inputting instructions for setting, selecting, determining, and executing various conditions when the image forming apparatus is used, as well as settings, operating states, and various conditions of the image forming apparatus. And a display unit 120 for displaying information input through the operation unit 110. The display unit 120 may be a general liquid crystal display screen or a lamp, but normally, a touch panel type liquid crystal display screen capable of instructing and inputting information in addition to displaying information is used. . The instruction information input from the operation unit 110 of the operation display unit 100 is transmitted to the control unit 7. In addition, a predetermined display is performed on the display unit 120 of the operation display unit 100 by a control operation of the control unit 7 or the like.
[0036]
In this color image forming apparatus, in addition to performing general image output (copying and printing) by giving a predetermined instruction from the operation display unit 100, camera data is taken in from the DSC and image output (photo printing) ) Can be done.
[0037]
That is, by performing an operation for switching setting of display contents in the operation unit 110 of the operation display unit 100, an image output mode (general print mode) other than output based on camera data from the DSC and the DSC are displayed on the display unit 120. A screen on which one of the related image output modes (photo print) can be selected is displayed, and one of the output modes can be selected and instructed. The selection instruction at this time is performed directly from the display unit 120 including a touch panel type liquid crystal display screen or from the operation unit 110.
[0038]
At this time, when a DSC-related image output mode is selected, a display (for example, a message) prompting the input of camera data from the DSC input unit 9 is displayed on the display unit 120. In accordance with this, the camera data input operation from the DSC input unit 9 is performed.
[0039]
Further, in this color image forming apparatus, an image forming operation is performed by selecting and setting a predetermined image forming process pattern in which the order and types of the image forming process and the fixing process are appropriately combined according to each output mode described above. It has become so.
[0040]
That is, when performing the image formation, when the general print mode is selected, a process pattern that executes only the first fixing by the first fixing device 4 after executing the image forming process is selected and executed. Further, when the photo print mode is selected, a process of performing the first fixing by the first fixing device 4 after performing the image forming process on the recording sheet P and further performing the second fixing by the second fixing device 5. A pattern is selected and executed.
[0041]
Hereinafter, main operations (operations after the image forming process) of the image forming apparatus when the above-described output modes are selected will be described.
[0042]
First, when a general print mode is selected, image forming data obtained by converting image data input by the document reading device 8 is sent from the image processing unit 6 to the exposure device 13 of the image forming system 2. It is done. In the image forming system 2, a toner image is formed based on the image forming data and is transferred to the plain paper P1 fed from the paper feed cassette 31A. Next, the plain paper P1 onto which the toner image has been transferred is fixed by the first fixing device 4 and then discharged through the discharge conveyance path R3 by the guidance of the conveyance direction switching gate 35. As a result, a general image based on the image data input by the document reading device 8 is formed on one side of the plain paper P1.
[0043]
Incidentally, when double-sided image formation is performed, after image formation (transfer of toner image and first fixing) on one side of the recording paper P2 is completed, the image is formed through the reverse conveyance path R4 by guidance of the conveyance direction switching gate 36. By being retransmitted to the image system 2 and sent to the first fixing device 4, an image is formed on the back surface thereof, and finally discharged through the discharge conveyance path R <b> 3. As a result, images are formed on both sides of the plain paper P1.
[0044]
On the other hand, when the photo print mode is selected, image forming data obtained by converting image data from the DSC input unit 9 to the exposure device 13 of the image forming system 2 from the image processing unit 6 is subjected to image processing. Sent from unit 6. In the image forming system 2, a toner image is formed based on the image forming data, and the surface of the photographic print recording paper P2 fed from the paper feed cassette 31B (formation surface of the image receiving layer 72) is formed. Transcription is performed. Next, the photographic print recording paper P2 to which the toner image has been transferred is sent to the first fixing device 4 and fixed, and then the second fixing is performed through the second fixing conveyance path R2 by the guidance of the conveyance direction switching gate 35. It is sent to the apparatus 5 for re-fixing and finally discharged onto the discharge tray 39.
[0045]
By executing this photographic print mode, a photographic image based on the imaging data is formed on one side (formation surface of the image receiving layer 72) of the photographic print recording paper P2. In particular, when photographic printing is performed using the photographic printing recording paper P2 on which the image receiving layer 72 is formed, the toner image is heated and melted in the first fixing as shown in FIG. The toner image T1 is slightly buried in the surface of the surface 72 and slightly protruded from the surface (toner image T1). However, as shown in FIG. And the surface is smooth (toner image T2).
[0046]
As shown in FIG. 4, the image receiving layer 72 and the image receiving layer 71 of the recording sheet P2 for photographic print melted by being heated and pressurized by the heating roll 51 and the pressure roll 55 in the second fixing device 5 are also melted. The first fixed toner image T1 in the pressed state is cooled by the cooler 56, so that the entire surface of the image receiving layer 72 including the toner image T1 is made smooth according to the surface of the fixing belt 54. This is presumed to be due to solidification in the surface state. As a result, it is possible to form a photographic image with high gloss. Reference numeral 57 in FIG. 7 denotes a halogen lamp as a heating source.
[0047]
Next, the following tests were performed using this image forming apparatus.
[0048]
First, a value obtained by averaging the maximum value and the minimum value of the glossiness of one recording sheet P (average gloss, which is actually a value obtained by averaging the glossiness Gt of the toner image portion and the glossiness Gp of the recording sheet) And the degree of discomfort of each image at that time compared to the image quality of silver halide photographs.
[0049]
Test 1 was performed based on samples (see FIG. 5) whose average gloss was different by 10% between a numerical range of 30 to 110. Actually, as the recording sheet P, the recording sheet P having a surface glossiness Gp of 25 to 95% was used. The toner image has a glossiness Gt of 40 to 115% (the toner image is magenta M and the toner adhesion amount is 0.45 mg / cm ² Solid image). At this time, the glossiness Gt of the toner image was changed by adjusting the second fixing temperature, the second fixing speed, and the type of the recording sheet to perform image formation. The glossiness was measured with the above-mentioned gloss meter.
[0050]
A sensory evaluation test was performed on each image obtained for each average gloss. In this sensory evaluation test, impressions when six sensory testers looked at each image to be tested and compared with the image quality of a silver salt photograph were evaluated based on the following grade (G) standards. An average of the evaluation results is shown in FIG. In this case, the allowable level is G2 or less.
G1: There is no image quality and inferiority of silver halide photographs.
G2: I feel a little uncomfortable, but I don't mind.
G3: There is a sense of incongruity and I am interested.
G4: Very uncomfortable.
[0051]
From the results of FIG. 5, it can be seen that the condition of the image having almost no sense of discomfort with the image quality of the silver salt photograph is that the average gloss difference is at least 90% or more, preferably 110% or more. Incidentally, the upper limit value of each glossiness Gp, Gt is not particularly limited. Further, the glossiness of ordinary silver salt photographs is about 95 to 105%.
[0052]
Subsequently, based on this result, the difference between the glossiness Gt of the toner image portion and the glossiness Gp of the sheet (gross difference: Gt−Gp), and each image at that time is compared with the image quality of the silver halide photograph. The relationship of whether or not to feel a sense of discomfort (gloss level difference) was examined.
[0053]
The test 2 was performed based on samples (see FIG. 6) in which the gross difference differs by 10% (including 0%) within a numerical range of −40 to +50. Actually, as the recording sheet P, a sheet having a glossiness Gp of 20 to 95% on the surface thereof was used. The toner image has a glossiness Gt of 40 to 115% (the toner image is magenta M and the toner adhesion amount is 0.45 mg / cm ² Solid image).
[0054]
The sensory evaluation test was performed in the same manner as in Test 1 for each image obtained for each gloss difference. In this sensory evaluation test, whether or not the difference in glossiness of the image was particularly felt was observed, and the result was evaluated based on the following grade (G) standard. The average of the evaluation results is shown in FIG. In this case, the allowable level is G2 or less.
G1: There is no difference in glossiness.
G2: I feel a slight difference in glossiness, but I don't mind.
G3: There is a difference in glossiness and it is anxious.
G4: It feels very glossy and feels strange.
[0055]
From the results shown in FIG. 6, it can be seen that the condition of the image having almost no sense of incongruity with the image quality of the silver salt photograph is that the gross difference is at least 30% or less, preferably 0%. When the glossiness Gt of the toner image portion is lower than the glossiness Gp of the recording sheet (Gt <Gp), the image appears to have sunk into the recording sheet, It was confirmed that the feeling of discomfort was stronger than the image quality. From the results shown in FIGS. 5 and 6, it is safe that the glossiness Gt of the toner image portion and the glossiness Gp of the sheet are both 90% or more as a condition that the feeling of discomfort with the image quality of the silver salt photograph is not reliably received. It can be seen that it is.
[0056]
Subsequently, based on these results, the level difference h between the toner image portion and the recording sheet, and how much discomfort (gloss level difference) each image has compared with the image quality of the silver halide photograph at that time. I investigated the relationship.
[0057]
In this test 3, different second fixing loads (loads of the pressure roll 55 of 30 to 200 kg weight) and second fixing speeds (the printing sheet P2 for photo print, Gp = 95%) and the second fixing speed ( 52 to 220 mm / sec) and the second fixing temperature (140 ° C. to 180 ° C.). As the toner image, an image of “ten” in magenta color was formed. Regarding the first fixing conditions, the pressure pad load was 33 kg and the fixing temperature was 140 ° C. The level difference h was measured with the laser focus displacement meter described above.
[0058]
For each image obtained for each step h, a sensory tester similar to that in Test 1 observes the state of the step, and contrasts the results assuming the image quality of a silver salt photograph, and the following grade (G) Evaluated by criteria. An average of the evaluation results is shown in FIG. In this case, the allowable level is G3 or less.
G1: A step cannot be visually recognized.
G2: A level difference can be visually recognized slightly.
G3: I can clearly see the difference in level, but I don't care.
G4: I'm worried about the step, but it's not uncomfortable.
G5: It is unpleasant that there is a step.
G6: It is quite uncomfortable that there is a step.
G7: It is very uncomfortable that there is a step.
[0059]
From the result of FIG. 7, as the condition of the image with almost no sense of incongruity between the image quality of the silver halide photograph and the presence or absence of the step, the step h Less It can be seen that this is at least 3 μm or less.
[0060]
When the above tests 1 to 3 are combined, at least Gp ≧ 90, Gt ≧ 90, and Gp ≦ Gt are satisfied, and h ≦ 3 μm as the image conditions that are almost uncomfortable with the image quality of the silver salt photograph. It was found that this was the time when the relationship was established. In particular, the conditions relating to the glossiness Gp and Gt at this time are shown in a graph as shown in FIG. The hatched portion S is a region that satisfies the above three conditions regarding the glossiness. For reference, the above-described conditions related to the glossiness of the prior art are also shown (the portion Z sandwiched between two dotted lines is a region that satisfies the conditions).
[0061]
From this point of view, image formation was performed in the photographic print mode under the following conditions, and the glossiness Gt of each image at that time was examined.
[0062]
As the recording sheet P, photographic printing recording paper P2 having a glossiness Gp of 93 was used. The glossiness Gp of the recording paper P2 varies slightly in the measurement stage after the second fixing (refer to the vertical axis values when the horizontal axis is zero in FIGS. 9 and 10: 93 to 96%). This is because the pressure distribution in the axial direction of the second fixing device 5 and the cooling temperature vary.
[0063]
As the toner image, the four-color (Y, M, C, B) single-color image and at least two of the four colors are used as red (R), green (G), blue (Bl), A color image (PK) composed of three color toners of Y, M, and C, and a full color (4FC) color image composed of four color toners of Y, M, C, and B were formed. As for the monochromatic image and the color image, as shown in FIG. 11, the gradations (Cin) of each gradation (Cin) within the range of 0 to 100% for each color on the same recording sheet are blocked in a line in the sheet feeding direction. Formed side by side. The horizontal (horizontal) direction in FIG. 11 shows the arrangement of blocks for each color, and the vertical direction shows a block row arranged for each gradation of each color.
[0064]
The first fixing conditions at this time were a pressure pad load of 33 kg, a fixing temperature of 140 ° C., and a fixing speed of 52 mm / sec. The second fixing conditions were a load of 120 kg of the pressure roll 55, a fixing speed of 52 mm / sec, a fixing temperature of 145 ° C., and a cooling target temperature by the cooling device 56 of 60 ° C.
[0065]
The glossiness Gt of each obtained image was measured with the above-mentioned gloss meter. FIG. 9 shows the results regarding the monochromatic image at this time, and FIG. 10 shows the results regarding the color image. Further, all of the obtained images have a step h of 3 μm or less. Each printed matter obtained in this manner was of a high quality without any discomfort with the image quality of the silver halide photograph.
[0066]
<< Other Embodiments >>
In the image forming apparatus according to the first embodiment, the case where the first fixing device 4 is provided in addition to the belt fixing device as the second fixing device 5 is illustrated, but the first fixing device 4 is not provided and the first fixing device 4 is not provided. It can also be configured as an image forming apparatus including only the two fixing device 5. In this case, the fixing process in the photo print mode is only the fixing by the belt fixing device as the second fixing device 5, but even in this case, the image receiving sheet P2 as the recording sheet P2 is used as the recording sheet P. If a recording sheet having a layer is used, it is possible to obtain a high-quality image that satisfies the above-described conditions and does not feel uncomfortable with the image quality of a silver salt photograph.
[0067]
In the first embodiment, the case where the drum-shaped photoconductor (11) is used as the image forming system 2 is exemplified. However, in the present invention, a belt-shaped photoconductor may be applied. Further, as the image forming system 2, there is a configuration in which a single photosensitive drum 11 is provided, and four developing devices (those that individually store the four color developers) are sequentially arranged around the photosensitive drum, A configuration may be used in which four developing devices are displaced and opposed to the photosensitive drum one by one.
[0068]
【The invention's effect】
As described above, according to the image forming method and apparatus of the present invention, it is possible to easily and reliably obtain a high-quality image that is not sensuously uncomfortable with the image quality of a silver salt photograph.
[Brief description of the drawings]
FIG. 1 is a schematic diagram illustrating a color image forming apparatus used in an image forming method according to a first embodiment.
FIG. 2 is a schematic cross-sectional view showing a photographic print recording paper as a recording sheet.
FIGS. 3A and 3B show a state when image fixing is performed by outputting an image on a photographic print recording sheet, FIG. 3A is a schematic sectional view showing a state after the first fixing, and FIG. 3B is a second fixing. FIG. 3 is a schematic cross-sectional view showing a state after (belt fixing).
FIG. 4 is a main part explanatory view showing a state of fixing processing by a belt fixing device.
FIG. 5 is a graph showing the relationship between the average gloss and the sensory blade (Test 1).
FIG. 6 is a graph showing the relationship between the gloss difference and the sensory blade (Test 2).
FIG. 7 is a graph showing a relationship (test 3) between an image step and a sensory blade.
FIG. 8 is a graph showing a preferable condition range for glossiness Gp, Gt and a condition range defined in the prior art.
FIG. 9 is a graph showing measurement results of glossiness of a single color image.
FIG. 10 is a graph showing the measurement result of the glossiness of a color image.
FIG. 11 is an explanatory plan view showing a state in which a single color image and a color image are formed on one recording sheet by gradation.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 2 ... Image forming system, 4 ... 1st fixing device (other fixing device), 5 ... 2nd fixing device (belt fixing device), 51 ... Heating roll (a part of heating-pressing means), 55 ... Pressure roll (Part of heating and pressing means), 54... Fixing belt, 56... Cooler (cooling means), P... Recording sheet (image support material), P 2 .. photographic printing recording paper (recording sheet on which image receiving layer is formed) , T: Toner image.

Claims (5)

In an image forming method of forming an image by transferring and fixing an image made of toner to an image support material,
Gp (%) is the glossiness of the surface of the image support material, and Gt (%) is the glossiness of an image portion formed of a toner image having a gradation in the range of 0 to 100% formed on the image support material. When Gp ≧ 90, Gt ≧ 90 and Gp ≦ Gt are established,
An image forming method comprising: forming an image satisfying a relationship of h ≦ 3 μm where h is a level difference between the image portion and the surface of the image support material. The image forming method according to claim 1, wherein the image supporting material is a recording sheet in which an image receiving layer made of a polyolefin resin is formed on at least one surface of a sheet-like substrate. In an image forming apparatus for forming an image by transferring and fixing an image made of toner to an image support material,
As a fixing device for performing the fixing, a rotating endless fixing belt having a smooth surface, and a heating and pressing unit that heat-presses and adheres the image support material after the toner image is transferred to the surface of the fixing belt; A belt fixing device having at least a cooling unit that cools the image supporting material conveyed in close contact with the surface of the fixing belt by the heating and pressing unit,
Gp (%) is the glossiness of the surface of the image support material, and Gt (%) is the glossiness of an image portion formed of a toner image having a gradation in the range of 0 to 100% formed on the image support material. If Gp ≧ 90, Gt ≧ 90, and Gp ≦ Gt, the relationship of h ≦ 3 μm is satisfied when the step difference between the image portion and the image support material surface is h. An image forming apparatus for forming an image. As the fixing device, another fixing device is provided separately from the belt fixing device,
The image forming apparatus according to claim 3, wherein fixing is performed by a belt fixing device after at least fixing by another fixing device.   The image forming apparatus according to claim 3 or 4, wherein the image supporting material is a recording sheet in which an image receiving layer made of a polyolefin resin is formed on at least one surface of a sheet-like base material.

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