JP2013015808A - Image formation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image formation device capable of obtaining favorable transferability similar to that of a toner image formed only by chromatic toner, even when using transparent toner.SOLUTION: An image formation device includes: means for forming a toner adhesion amount detection pattern on an intermediate transfer belt; a toner adhesion amount detection section for detecting the toner adhesion amount of the toner adhesion amount detection pattern formed on the intermediate transfer belt; and a control section for controlling image formation conditions on the basis of the detection result by the toner adhesion amount detection section. When forming an image by using chromatic toner, the device forms the toner adhesion amount detection pattern 91 using the chromatic toner. When forming an image by using both chromatic toner and transparent toner, the device forms the toner adhesion amount detection patterns 91 and 92 by using both chromatic toner and transparent toner.

Description

  The present invention relates to an electrophotographic image forming apparatus capable of forming a color image using an intermediate transfer member.

As an electrophotographic image forming apparatus, for example, a charging unit that uniformly charges the surface of a photoconductor as an image carrier, an exposure unit that forms a latent image on the charged photoconductor, and a latent image formed on the photoconductor. An image forming unit comprising: a developing unit that applies toner to an image to form a toner image; and a transfer unit that transfers a toner image formed on a photoreceptor onto an intermediate transfer belt as an intermediate transfer member; Some image forming units and corresponding photoconductors are arranged side by side along an intermediate transfer belt to form a plurality of image forming stations.
In recent electrophotographic apparatuses that form color images, such as copying machines and printers, the quality demanded by the market has been increasing, and gloss may be formed in the printed image. To meet this need, in electrophotography, a developing device that forms a transparent toner image is installed upstream of a developing device that forms a colored toner image, so that the gloss that is formed on the colored toner image with the transparent toner on the recording medium. A surface can be generated.

In order to obtain a high-quality image in an electrophotographic image forming apparatus, it is necessary to transfer toner images onto a recording medium. The toner image on the intermediate transfer member represented by the belt is transferred to the recording medium by applying a bias. This bias has an appropriate value depending on the image area ratio in the main scanning direction (longitudinal direction of the photosensitive member). Different.
Patent Document 1 discloses an image forming apparatus in which toner images having different image area ratios in the main scanning direction are formed on an intermediate transfer body, each toner image is read by a toner adhesion amount detection sensor, and appropriate transfer conditions are selected. Yes. However, this image forming apparatus is not configured to form an image using a transparent toner, and when using a transparent toner, it is not possible to obtain a good transfer property as with a toner image formed only with colored toner. There is a fear.

  The present invention has been made under the above-described background, and its object is to provide an image forming apparatus that obtains good transferability as well as a toner image formed only with a colored toner even when a transparent toner is used. It is in.

  The present invention forms a latent image on an image carrier, and transfers a toner image obtained by developing the latent image with only colored toner or both colored toner and transparent toner to an intermediate transfer member, In an image forming apparatus for forming an image on the recording medium by transferring the toner image transferred onto the intermediate transfer member to a recording medium and fixing the toner image by applying heat, the image is formed on the intermediate transfer member. Means for forming a toner adhesion amount detection pattern, a toner adhesion amount detection unit for detecting the toner adhesion amount on the intermediate transfer member, and a control unit for controlling image forming conditions based on the detection result of the toner adhesion amount detection unit When forming an image with only the color toner, a toner adhesion amount detection pattern is formed with the color toner, and when forming an image with both the color toner and the transparent toner, It is characterized in forming a toner adhesion amount detection pattern in both color toners and transparent toner.

  According to the present invention, when an image is formed only with colored toner, the toner adhesion amount of the toner adhesion amount detection pattern formed with the color toner is detected, and the image forming condition is controlled based on the detection result. In addition, when forming an image with both colored toner and transparent toner, the toner adhesion amount of the toner adhesion amount detection pattern formed with both colored toner and transparent toner is detected, and the image forming condition is determined based on the detection result. Control. As a result, even when a transparent toner is used, good transferability can be obtained as in the case of a toner image formed only with colored toner.

1 is a schematic diagram illustrating an example of an overall configuration of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a schematic configuration diagram schematically illustrating an example of a configuration of an image forming unit in the image forming apparatus according to the present embodiment. FIG. 2 is a side view showing a main configuration of a transfer device in the image forming apparatus according to the present embodiment. FIG. 4 is a schematic diagram illustrating a toner adhesion amount detection pattern on an intermediate transfer belt in the image forming apparatus according to the embodiment. FIG. 6 is a schematic diagram illustrating a toner adhesion amount detection pattern in a mode in which transparent toner on an intermediate transfer belt is used in the image forming apparatus according to the present embodiment. FIG. 6 is a schematic diagram illustrating a cross-sectional structure of a color toner, a transparent toner, and a recording medium on an intermediate transfer belt in a conventional apparatus. FIG. 4 is a schematic diagram illustrating an example of a cross-sectional structure of a color toner, a transparent toner, and a recording medium on an intermediate transfer belt in the present embodiment. FIG. 6 is a schematic diagram illustrating another example of the cross-sectional structure of the color toner and the transparent toner on the intermediate transfer belt and the recording medium in the present embodiment. FIG. 3 is a block diagram illustrating an example of a main configuration of a control system in the image forming apparatus according to the present embodiment. FIG. 4 is a schematic diagram illustrating a transparent toner image on a recording medium on an intermediate transfer belt and a leading end in a conveyance direction.

The best mode for carrying out the present invention will be described below with reference to the drawings.
Note that it is easy for a person skilled in the art to make other embodiments by changing or correcting the present invention within the scope of the claims, and these changes and modifications are included in the scope of the claims. The following description is an example of the best mode of the present invention, and does not limit the scope of the claims.

FIG. 1 is a schematic diagram illustrating an example of the overall configuration of an image forming apparatus according to an embodiment of the present invention.
FIG. 2 is a schematic configuration diagram schematically illustrating an example of a configuration of an image forming unit in the image forming apparatus.
The image forming apparatus 1 shown in FIG. 1 has an image forming unit 10 as a toner image forming unit that can also be used as a process cartridge arranged in parallel, and temporarily superimposes an image on an intermediate transfer belt 61 as an intermediate transfer member. This is a system in which it is collectively transferred to a recording medium 6 such as paper. In addition, the image forming apparatus 1 has process cartridges that serve as the image forming unit 10 arranged in parallel, and is a system in which toner images are sequentially transferred onto the conveyance belt 66 while the recording medium 6 is conveyed.

  As shown in FIG. 1, the image forming apparatus 1 includes an automatic document feeder (ADF) 5 that automatically feeds a placed document 7 from above, a scanner (reading device) 4 that reads the document 7, An image forming unit 3 that forms a toner image, and a recording medium 6 such as a recording sheet are provided below the image forming unit 3 and a paper feeding unit 2 that supplies the recording medium 6 is disposed.

Further, as shown in FIGS. 1 and 2, the image forming apparatus 1 has an image forming unit 3 disposed at the center thereof. In the image forming unit 3, there are four toners corresponding to the colored toners of yellow (Y), cyan (C), magenta (M), and black (K) and a transparent toner (colorless and transparent toner) in the center of the image forming unit 3. Five image forming units 10 as process cartridges combined with one corresponding to Tr) are arranged in a tandem type arranged in parallel in the horizontal horizontal direction.
This is an overcoat with a transparent toner (Tr) when the image surface of a colored toner such as yellow, cyan, magenta, black (Y, C, M, K) toner is covered with the transparent toner (Tr). The overcoat layer serves to protect the image surface of the colored toner. The surface shape of the recording medium 6 is changed by the transparent (Tr) toner.
Further, by creating a pattern with a transparent toner on the recording medium 6 having a smooth surface, a texture like fancy paper can be given. The texture can be changed by increasing / decreasing the amount of the transparent toner attached on the recording medium 6. In particular, when the amount of attached toner is large, the effect of the transparent toner on the recording medium 6 is more remarkable on the outermost surface.
However, the image forming order of the transparent toner may be other image forming orders, and is not particularly limited to the example described here.

  Above the five image forming units 10Tr, 10Y, 10C, 10M, and 10K, an exposure apparatus that exposes the surface of each charged electrostatic latent image carrier 11 based on the image data of each color to form a latent image. 12 is provided. Further, below the five image forming units 10Tr, 10Y, 10C, 10M, and 10K, endless belts made of a heat-resistant material such as polyimide and polyamide and having a base adjusted to a medium resistance are provided with rollers 651, 652, A transfer device 60 including an intermediate transfer belt 61 that is supported by being wound around 653 and rotated is disposed. Since any image forming unit 10 has the same configuration, the subscripts Tr, Y, C, M, and K are omitted in the description using FIG.

  Each of the image forming units 10Tr, 10Y, 10C, 10M, and 10K includes an electrostatic latent image carrier 11Tr, 11Y, 11C, 11M, and 11K. A charging device 20 for applying a charge to the surface of the image carrier 11; a developing device 30 for developing a latent image formed on the surface of the electrostatic latent image carrier 11 with each color toner to form a toner image; and a surface of the electrostatic latent image carrier 11 Further, a lubricant application device for applying a lubricant (not shown) and a cleaning device 40 having a cleaning blade for cleaning the surface of the electrostatic latent image carrier 11 after the toner image transfer are arranged. Thus, one image forming unit 10 is formed.

  The electrostatic latent image carrier 11 is made of a metal such as amorofus silicone or selenium, or an organic system. The organic electrostatic latent image carrier 11 has a resin layer in which a filler is dispersed, a photosensitive layer having a charge generation layer and a charge transport layer on a conductive support, and a protective layer in which a filler is dispersed on the surface.

The photosensitive layer may be a single-layered photosensitive layer containing a charge generation material and a charge transport material, but a laminated type composed of a charge generation layer and a charge transport layer is excellent in sensitivity and durability.
In the charge generation layer, a pigment having charge generation ability is dispersed in a suitable solvent together with a binder resin as necessary using a ball mill, an attritor, a sand mill, an ultrasonic wave, etc., and this is coated on a conductive support. It is formed by drying. As binder resin, polyamide, polyurethane, epoxy resin, polyketone, polycarbonate, silicone resin, acrylic resin, polyvinyl butyral, polyvinyl formal, polyvinyl ketone, polystyrene, polysulfone, poly-N-vinylcarbazole, polyacrylamide, polyvinyl benzal, polyester Phenoxy resin, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, polyphenylene oxide, polyamide, polyvinyl pyridine, cellulose resin, casein, polyvinyl alcohol, polyvinyl pyrrolidone and the like. The amount of the binder resin is suitably 0 to 500 parts by mass, preferably 10 to 300 parts by mass with respect to 100 parts by mass of the charge generating material.

The charge transport layer can be formed by dissolving or dispersing the charge transport material and the binder resin in a suitable solvent, and applying and drying the solution on the charge generation layer. Charge transport materials include hole transport materials and electron transport materials. As the binder resin, polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, Polyvinylidene chloride, polyarate, phenoxy resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl toluene, poly-N-vinyl carbazole, acrylic resin, silicone resin, epoxy resin, melamine resin, urethane resin, phenol Examples thereof include thermoplastic or thermosetting resins such as resins and alkyd resins.
In addition, a protective layer may be provided on the photosensitive layer. By providing the protective layer and improving the durability, the electrostatic latent image carrier 11 having high sensitivity and no abnormal defects of the present invention can be used effectively.
Materials used for the protective layer include ABS resin, ACS resin, olefin-vinyl monomer copolymer, chlorinated polyether, allyl resin, phenol resin, polyacetal, polyamide, polyamideimide, polyacrylate, polyallylsulfone, polybutylene, Examples thereof include resins such as polybutylene terephthalate, polycarbonate, polyarylate, polyethersulfone, polyethylene, polyethylene terephthalate, polyimide, acrylic resin, polymethylbenten, polypropylene, polyvinylidene chloride, and epoxy resin. Of these, polycarbonate or polyarylate can be most preferably used. Other protective layers include fluorine resins such as polytetrafluoroethylene, silicone resins, and inorganic fillers such as titanium oxide, tin oxide, potassium titanate, and silica for the purpose of improving wear resistance. What disperse | distributed the filler etc. can be added. The filler concentration in the protective layer varies depending on the type of filler used and the electrophotographic process conditions using the electrostatic latent image carrier 11, but the ratio of filler to the total solid content on the outermost layer side of the protective layer is 5 mass. % Or more, preferably 10% by mass or more and 50% by mass or less, preferably about 30% by mass or less.

  The charging device 20 includes a charging roller 21 configured by covering a conductive core bar with a medium-resistance elastic layer as a charging member. The charging roller is connected to a power source (not shown), and is applied with a predetermined direct voltage (DC) and / or alternating voltage (AC). The charging roller 21 that discharges ions uses an elastic resin roller as a material. In addition, the charging roller 21 may contain an inorganic conductive material such as carbon black or an ionic conductive material in order to adjust electric resistance.

  The charging roller 21 is disposed with a small gap with respect to the electrostatic latent image carrier 11. For example, the surface of the spacer member is brought into contact with the surface of the electrostatic latent image carrier 11 by winding a spacer member having a certain thickness around the non-image forming regions at both ends of the charging roller 21. This can be set. Further, the charging roller 21 may be brought into contact without being brought close to the electrostatic latent image carrier 11. The electrostatic latent image carrier 11 can be charged by discharging at a portion that is in the shape of a roller and is close to the electrostatic latent image carrier 11. Further, by making them close and not in contact with each other, it is possible to suppress the occurrence of contamination due to the transfer residual toner of the charging roller 21. In addition, the charging roller 21 is provided with a charging cleaner roller (not shown) that contacts the surface of the charging roller 21 for cleaning.

The developing device 30 uses a two-component developer having a magnetic carrier and toner. And in order to develop the electrostatic latent image carrier 11 which has a latent image, it is provided in the position which opposes.
Further, the developing device 30 includes a developer carrier 31 provided with a magnetic field generating means. Below the developer carrier 31, a stirring / conveying screw 34 having a mechanism for mixing toner introduced from a toner bottle (not shown) with the developer and pumping the toner to the developer carrier 31 while stirring is provided. Yes. The two-component developer composed of the toner and the magnetic carrier conveyed by the developer carrier 31 is regulated to a predetermined developer layer thickness by a pumping amount regulating member (not shown) and is carried on the developer carrier 31. The developer carrying member 31 carries and conveys the developer while moving in the same direction at a position facing the electrostatic latent image carrying member 11 and supplies the toner to the electrostatic latent image carrying member 11. In addition, toner cartridges for each color in which unused toner is stored are detachably stored in the space above the electrostatic latent image carrier 11. Toner is supplied as necessary to each developing device 30 by toner conveying means such as a mono pump or air pump (not shown). A toner cartridge for black toner that is highly consumed can be set to have a particularly large capacity.

  The cleaning device 40 includes a cleaning blade and a holder for holding the blade, and removes residual toner from the electrostatic latent image carrier 11 by pressing the blade member against the electrostatic latent image carrier 11. To do. In addition, the cleaning blade includes a mechanism for contacting / separating the electrostatic latent image carrier 11, and can be arbitrarily contacted / separated by a control unit described later of the image forming apparatus 1. The cleaning blade is brought into contact with the electrostatic latent image carrier 11 in a counter manner, whereby toner remaining on the electrostatic latent image carrier 11, talc of the recording medium adhering as dirt, kaolin, calcium carbonate, etc. The additive is removed from the electrostatic latent image carrier 11 and cleaned. The removed toner or the like is conveyed and stored in a waste toner container (not shown) by a waste toner collection coil (not shown).

  The toner that has been cleaned by the cleaning device 40 and removed from the electrostatic latent image carrier 11 is collected by a serviceman or the like by a toner conveying member, or is carried to a developing device or the like as recycled toner and used for development. .

  The transfer device 60 includes an intermediate transfer belt 61 on which toner images are stacked, a primary transfer roller 62 that transfers and stacks the toner images on the electrostatic latent image carrier 11 to the intermediate transfer belt 61, and the stacked toner images on a recording medium. A secondary transfer roller 63 as an opposing member to be transferred to 6 is provided. Further, the transfer device 60 is a portion facing the secondary transfer roller 63, and is provided inside the intermediate transfer belt 61 so that a support roller 653 serving as a facing member faces.

A primary transfer roller that primarily transfers a toner image formed on the electrostatic latent image carrier 11 onto the intermediate transfer belt 61 at a position facing each electrostatic latent image carrier 11 with the intermediate transfer belt 61 interposed therebetween. 62 are arranged. The primary transfer roller 62 is connected to a power source (not shown), and is applied with a predetermined direct current voltage (DC) and / or alternating current voltage (AC). The polarity of the voltage to be applied is opposite to the polarity of the charge of the toner, and the primary transfer is performed by drawing and moving from the electrostatic latent image carrier 11 to the intermediate transfer belt 61 side. The primary transfer roller 62 is preferably semiconductive by containing an inorganic conductive material such as carbon black and an ionic conductive material in order to adjust electric resistance. Even if the resistance value of the primary transfer roller 62 is different, the transfer efficiency is hardly changed. However, if the image area ratio is different, the transfer efficiency is greatly different, so that the transfer efficiency cannot be stably maintained. This is because the current flows preferentially to the portion where the toner is not present in the transfer nip portion. As a result, when the image area ratio is small, the transfer voltage value becomes low and the electric field necessary for transfer cannot be obtained sufficiently. is there. In particular, when the resistance value of the primary transfer roller 62 is low, the influence of the resistance value of the toner interposed in the transfer portion becomes large. When constant current control is employed in this way, it is desirable to use a primary transfer roller 62 having a high resistance value. However, if the resistance value exceeds 5 × 10 ⁸ Ω, a toner image is formed due to current leakage. The risk of disturbance is increased. Therefore, it is preferable to use a primary transfer roller having a resistance value in the range of 1 × 10 ⁵ Ω to 5 × 10 ⁸ Ω. The phenomenon that the current flows preferentially to the portion where the toner does not intervene is not only due to the above-described toner resistance, but also the primary transfer voltage applied to the metal core provided at the center of the primary transfer roller 62 and the electrostatic latent voltage. This is also because the potential difference from the image carrier 11 is larger at the portion where the toner is not developed than at the portion where the toner is developed, and thus the transfer current tends to flow toward the larger potential difference. This is because the toner image is the same as the charging polarity of the electrostatic latent image carrier 11, and the toner is developed at a place where the electrostatic potential is removed by receiving the image exposure of the electrostatic latent image carrier 11. This occurs when the image forming apparatus 1 forms a toner image on the electrostatic latent image carrier 11. The photosensitive member potential is high where the toner image is not formed and the photosensitive member potential is low where the toner image is formed, but the transfer potential is opposite to the photosensitive member potential, so the primary transfer voltage and the photosensitive member potential The difference is larger at the portion where the toner is not developed than at the portion where the toner is developed. In this case, the resistance value of the primary transfer roller 62 is desirably in the range of 5 × 10 ⁷ Ω to 5 × 10 ⁸ Ω.

  The toner image laminated on the intermediate transfer belt 61 is secondarily transferred to a recording medium by the secondary transfer roller 63. Similar to the primary transfer roller 62, the secondary transfer roller 63 is connected to a power source (not shown) and is applied with a predetermined DC voltage (DC) and / or AC voltage (AC). The polarity of the voltage to be applied is opposite to the polarity of the charge of the toner, and secondary transfer is performed by drawing and transferring from the intermediate transfer belt 61 to the conveyed recording medium side.

The secondary transfer roller 63 includes a cylindrical metal core made of metal, an elastic layer formed on the outer peripheral surface of the metal core, and a surface layer made of a resin material formed on the outer peripheral surface of the elastic layer. Has been.
The metal constituting the metal core is not particularly limited. For example, a metal material such as stainless steel or aluminum is used. Generally, a rubber material is used for the elastic layer formed on the cored bar to form a rubber layer. This is because the secondary transfer roller 63 is required to have an elastic function in order to deform the secondary transfer roller 63 and secure a secondary transfer nip portion, and the JIS-A hardness is 70 [ °] The following is desirable.
Further, when the cleaning blade 22 is used as a cleaning means for the secondary transfer roller 63, if the elastic layer is too soft, the contact state of the cleaning blade 22 becomes unstable and an appropriate cleaning angle cannot be obtained. Therefore, the hardness of the elastic layer is preferably JIS-A 40 [°] or more.
In addition, since the secondary transfer roller 63 cannot perform the function of transferring a toner image to a recording medium when an insulator is used, it is preferably a foamed resin agent having a conductive function and a thickness of 2 mm to 10 mm. As a material imparting a conductive function, EPDM or Si rubber in which carbon black is dispersed, NBR having an ionic conductive function, urethane rubber, or the like may be used.
Since most of the foamed resin agents used for the elastic layer have high chemical affinity for the toner and a large friction coefficient, the functions required for the surface layer with which the cleaning blade 22 is in contact are low friction coefficient, toner separation. Since the moldability is required, the surface layer of the secondary transfer roller 63 is used by adjusting the resistance by adding a resistance control material to the fluororesin resin.

  Further, since the secondary transfer roller 63 rotates in contact with the intermediate transfer belt 61, if a minute linear velocity difference occurs between the intermediate transfer belt 61 and the secondary transfer roller 63, the intermediate transfer belt 61. It will affect the driving of the. Therefore, since the sliding property with the intermediate transfer belt 61 is required for the surface layer of the secondary transfer roller 63, it is desirable to set the friction coefficient of the outermost surface layer to be 0.4 or less.

The intermediate transfer belt 61 is provided with an intermediate transfer belt cleaning device 64 that cleans the surface of the intermediate transfer belt 61 after the secondary transfer.
In addition, the support roller 653 includes a mechanism for contacting / separating with the intermediate transfer belt 61 and can be arbitrarily contacted / separated by the control unit of the main body of the image forming apparatus 1.

Further, the image forming apparatus 1 is provided with a lubricant applying device 45 that applies a lubricant to the intermediate transfer belt 61. The lubricant application device 45 includes a solid lubricant contained in a fixed case, a brush roller that contacts the solid lubricant, scrapes the lubricant, and is applied to the intermediate transfer belt 61 and a lubricant applied by the brush roller. A lubricant application blade for leveling is provided. The solid lubricant is formed in a rectangular parallelepiped shape and is urged toward the brush roller by a pressure spring. The solid lubricant is scraped off and consumed by the brush roller, and the thickness of the solid lubricant decreases with time. However, since the solid lubricant is pressurized by the pressure spring, the solid lubricant is always in contact with the brush roller. The brush roller applies the lubricant scraped off while rotating to the surface of the intermediate transfer belt 61.
Note that a lubricant application device having a similar function may be provided for the electrostatic latent image carrier 11.

  In this embodiment, a lubricant application blade (not shown) as a lubricant leveling means is brought into contact with the surface of the intermediate transfer belt 61 on the downstream side in the moving direction with respect to the lubricant application position by the brush roller. The lubricant application blade is made of rubber which is an elastic body, has a function as a cleaning means, and is in contact with the moving direction of the intermediate transfer belt 61 in the counter direction. As the solid lubricant, a dry solid hydrophobic lubricant can be used. In addition to zinc stearate, metal compounds having fatty acid groups such as stearic acid, oleic acid, and palmitic acid can also be used. . Further, waxes such as candelilla wax, carnauba wax, rice wax, wax, ooba oil, beeswax, and lanolin can be used.

The intermediate transfer belt 61 is composed of single layer or multiple layers of PVDF (vinylidene fluoride), ETFE (ethylene-tetrafluoroethylene copolymer), PI (polyimide), PC (polycarbonate), etc., and is made of conductive material such as carbon black. The volume resistivity is adjusted to be in the range of 10 ⁸ to 10 ¹² Ωcm, and the surface resistivity is adjusted to be in the range of 10 ⁹ to 10 ¹³ Ωcm. If necessary, a release layer may be coated on the surface of the intermediate transfer belt 61. Materials used for the coating include ETFE (ethylene-tetrafluoroethylene copolymer), PTFE (polytetrafluoroethylene), PVDF (vinylidene fluoride), PEA (perfluoroalkoxy fluorocarbon resin), FEP (four-fluorocarbon). Fluorine resin such as ethylene fluoride-propylene hexafluoride copolymer) or PVF (vinyl fluoride) can be used, but is not limited thereto.
The method of manufacturing the intermediate transfer belt 61 includes a casting method, a centrifugal molding method, and the like, and the surface thereof may be polished as necessary.
If the volume resistivity of the intermediate transfer belt 61 exceeds the above-described range, the bias necessary for transfer increases, which increases the power supply cost, which is not preferable. Further, since the charging potential of the intermediate transfer belt 61 becomes high in the transfer process, the recording medium peeling process, and the like, and self-discharge becomes difficult, it is necessary to provide a static elimination means. Also, if the volume resistivity and surface resistivity are below the above ranges, the charge potential decays faster, which is advantageous for static elimination by self-discharge, but toner scattering occurs because the current during transfer flows in the surface direction. End up. Therefore, the volume resistivity and the surface resistivity of the intermediate transfer belt 61 in the present invention must be within the above ranges.
The volume resistivity and surface resistivity were measured by connecting an HRS probe (inner electrode diameter 5.9 mm, ring electrode inner diameter 11 mm) to a high resistivity meter (manufactured by Mitsubishi Chemical Co., Ltd .: Hiresta IP). The measured value 10 seconds after applying the voltage of 100V (surface resistivity is 500V) to the front and back of the was used.

  On the left side of the transfer device 60 is provided a fixing device 70 that fixes the toner image on the recording medium 6 to the recording medium 6 semipermanently. Although not shown, the fixing device 70 is mainly composed of a fixing roller 71 having a halogen heater inside, and a pressure roller 72 disposed so as to be opposed to and pressed against the fixing roller 71. The fixing device 70 is controlled by a control unit (not shown) so as to control fixing conditions based on full-color and monochrome images, or single-sided or double-sided, and optimal fixing conditions according to the type of the recording medium 6.

When the double-sided copy mode is selected, the recording medium 6 having an image fixed on one side is conveyed to the recording medium reversing device 89 side by the switching claw 851, and a plurality of predetermined arrangements are provided in the reversing conveyance path 87. The recording medium surface 9 is reciprocated by a reversing transport path 87 formed in advance by a transport roller or a guide member (not shown) to reverse the vertical direction of the recording medium surface 9 and then switched again by the switching claw 852 to form an image. Is returned to the transfer path for the transfer, and transferred on the transfer path to the registration roller 84 again. Here, the position and direction of the recording medium 6 are aligned again and sent to the registration roller 84. Therefore, even when an image is formed on the back surface of the recording medium 6, the images on the front and back surfaces of the recording medium 6 can be aligned.
Further, after being guided to the transfer device 60 and this time transferring and fixing an image on the back surface of the recording medium 6, the image is finally discharged onto a paper discharge tray 86 by a paper discharge roller 85.
At this time, when the number of the recording medium 6 is one, the recording medium 6 surface is reversed upside down, and then passes through the reverse conveying path 87 of the recording medium reverse conveying device 89 and is again formed by the registration rollers 84. After the image is formed by the unit 10, the image is formed on the recording medium 6 by the transfer roller 63. This time, after the image is transferred and fixed on the back surface of the recording medium 6, it is finally discharged onto the paper discharge tray 86 by the paper discharge roller 85.
When there are a plurality of recording media 6, the recording medium reversing and storing device 88 in the recording medium reversing and conveying device 89 temporarily stores the recording medium 6 having a set number of toner images on one side, and then from there, The paper is fed by the paper feed roller 812, separated one by one by the separation roller 811, and after the image is formed again by the image forming unit 10 by the registration roller 84, the image is formed on the recording medium 6. Is done. This time, after the image is transferred and fixed on the back surface of the recording medium 6, it is finally discharged onto the discharge tray 86 by the discharge roller 85.
The process cartridge 10 serving as an image forming unit includes a charging device 20, a developing device 30, a cleaning device 40, and a lubricant coating device (not shown) with the electrostatic latent image carrier 11 as a center. The process cartridge 10 integrally supports at least the electrostatic latent image carrier 11 and the developing device 30 and is detachable from the image forming apparatus 1.

An image forming operation in the image forming apparatus 1 of the present invention configured as described above will be briefly described.
The photoconductor 11 of the image forming unit 10 is rotationally driven counterclockwise in the figure by a driving unit (not shown), and the surface of the photoconductor 11 is uniformly charged to a predetermined polarity by the charging device 20. The charged surface of the photoconductor is irradiated with scanning light from the exposure device 12, thereby forming an electrostatic latent image on the surface of the photoconductor 11. At this time, the image information exposed on each photoconductor 11 includes a total of five types of information, that is, single-color image information obtained by separating a desired full-color image into color information of yellow, magenta, cyan, and black, and transparent toner. Each color toner is applied from the developing device 30 to the electrostatic latent image formed in this way, and visualized as a toner image.
Further, the intermediate transfer belt 61 is driven to run clockwise in the drawing, and the respective color toner images are sequentially transferred from the photoreceptor 11 to the intermediate transfer belt 61 by the action of the primary transfer roller 62 in each image forming unit 10. In this way, the intermediate transfer belt 61 carries a full-color toner image on its surface.

A single color image can be formed using any one of the image forming units 10, or a two-color or three-color image can be formed using a plurality of image forming units 10. In the case of monochrome printing, image formation is performed using the black image forming unit 10K among the five image forming units 10.
Residual toner adhering to the surface of the photoconductor 11 after the toner image is transferred is removed from the surface of the photoconductor 11 by the cleaning device 40, and then the surface is subjected to the action of the static eliminator 13 to initialize the surface potential. In preparation for the next image formation.
The recording medium 6 is fed from the paper feed tray 81, and sent to the secondary transfer position by the registration roller 84 in a timing with the toner image carried on the intermediate transfer belt 61. The toner image on the surface of the intermediate transfer belt 61 is collectively transferred onto the recording medium 6 by the secondary transfer roller 63 as the second transfer unit. When the toner image is fed to the fixing device 70 and passes through the fixing device 70, the toner image is melted and fixed on the recording medium 6 by heat and pressure. The recording medium 6 on which the toner image is fixed is discharged to a paper discharge tray 86.
The use environment recognizing means of the image forming apparatus 1 is composed of a temperature / humidity sensor (not shown). The temperature / absolute humidity is read, and the image is developed under the development conditions, transfer conditions, and fixing conditions set based on the reading results. Form.

  FIG. 3 is a side view showing the main configuration of the transfer device in the image forming apparatus according to the present embodiment. As shown in this figure, the intermediate transfer belt 61 is stretched over a drive roller 651, a driven roller 652, an external stretching roller 653, a transfer counter roller 631, and a transfer guide roller 632, and the drive roller 651 is not shown. Is driven in the direction of arrow A in the figure. The driven roller 652 applies tension to the intermediate transfer belt 61 by a load applying unit (not shown), and generates a friction conveying force between the driving roller 651 and the intermediate transfer belt 61.

  As described with reference to FIG. 1, the photosensitive members 11 of the respective color image forming units 10 are arranged in parallel on the upper running side of the intermediate transfer belt 61 which is a belt stretching surface formed by the driving roller 651 and the driven roller 652. A primary transfer roller 62 serving as a primary transfer unit is disposed in the loop of the intermediate transfer belt 61 so as to face each photoconductor 11.

  A secondary transfer roller 63 is disposed below the transfer counter roller 631 and is pressed against the transfer counter roller 631 with the intermediate transfer belt 61 interposed therebetween. A predetermined high voltage is applied to the secondary transfer roller 63 from a transfer power source (not shown), and an electrostatic bias is applied between the secondary transfer roller 63 and the transfer counter roller 631. Further, the secondary transfer roller 63 conveys the recording medium 6 with a predetermined pressing force together with the transfer counter roller 631 and the intermediate transfer belt 61. Further, a transfer guide roller 632 is disposed on the back side of the intermediate transfer belt 61 and in the vicinity of the upstream side of the transfer counter roller 631 in the belt rotation direction. The secondary transfer roller 63, the transfer counter roller 631, and the transfer guide roller 632 constitute a secondary transfer portion. As can be seen from FIG. 3, the transfer guide roller 632 is disposed slightly outside the straight line connecting the outer peripheral surface of the drive roller 651 and the transfer counter roller 631, and the intermediate transfer belt 61 is moved from the belt inner side to the outer side. It is provided at a position where it is pushed out.

A belt cleaning device 64 for cleaning the intermediate transfer belt 61 is disposed outside the belt between the transfer counter roller 631 and the external stretching roller 653, and a backing roller corresponding to the cleaning blade 642 of the belt cleaning device 64. 641 is arranged inside the belt.
The recording medium 6 is conveyed in the direction of arrow B in the figure, and after the posture of the recording medium 6 is corrected by the registration roller pair 84, the recording medium 6 is conveyed between the secondary transfer roller 63 and the intermediate transfer belt 61. The upper toner image is electrostatically transferred onto the recording medium 6.

In the image forming apparatus 1 according to the present embodiment, toner adhesion amount detection units 67 and 68 are provided.
The toner adhesion amount detection unit 67 detects the amount of reflected light corresponding to the toner adhesion amount carried on the intermediate transfer belt 61. The toner adhesion amount detection unit 68 detects the reflected light amount corresponding to the untransferred toner adhesion amount on the intermediate transfer belt 61 after being transferred from the intermediate transfer belt 61 onto the recording medium 6. These are provided at an upstream portion in the rotational direction of a belt cleaning device 64 that removes untransferred toner from the intermediate transfer belt 61.
As the toner adhesion amount detection units 67 and 68, a light emitting element (LED) as a light emitting unit and a light receiving element (photodiode (PD) or phototransistor (PTr)) as a light receiving unit are combined to emit sensor light from the light emitting element. The sensor light is irradiated onto the toner image on the intermediate transfer belt, and the reflection type optical sensor that receives the sensor light passing through the toner image and reflected from the intermediate transfer belt by the light receiving element is structurally structured. It is preferable because it is simple.

  FIG. 4 is a schematic diagram showing a toner adhesion amount detection pattern on the intermediate transfer belt in the image forming apparatus according to the present embodiment. A toner adhesion amount detection pattern 91 is formed with colored toner in the main scanning direction on the photoreceptors 11Y, 11C, 11M, and 11K, which are image carriers, on the intermediate transfer belt 61. This adhesion amount detection pattern 91 is transferred to the intermediate transfer belt 61 which is an image carrier. Also, a plurality of toner adhesion amount detection patterns 91 may be arranged in parallel, and each toner adhesion amount detection pattern is detected and read by toner adhesion amount detection units 67 and 68 (see FIG. 2). For example, as shown in FIG. 4, when the toner adhesion amount detection patterns 91 are formed at two locations in the width direction orthogonal to the intermediate transfer belt surface movement direction, the toner adhesion amount detection units 67 and 68 have two locations, respectively. In order to be able to detect the toner adhesion amount detection pattern 91, detection portions are arranged at two locations where the two toner adhesion amount detection patterns 91 in the width direction pass.

FIG. 5 is a schematic diagram illustrating a toner adhesion amount detection pattern in a mode in which the transparent toner on the intermediate transfer belt is used in the image forming apparatus according to the present embodiment. Similar to FIG. 4, a color toner adhesion amount detection pattern 91 is generated on a toner adhesion amount detection pattern 92 generated in the main scanning direction with transparent toner.
In the mode using the transparent toner, the toner adhesion amount detection patterns 91 and 92 as shown in FIG. 5 are used to detect the adhesion amount, and the transfer condition is selected.
In a mode using transparent toner (such as a mode for generating gloss), colored toner is superimposed on the transparent toner image on the intermediate transfer belt 61. In this mode, when the image is formed only with the color toner, the transfer condition changes, and when the transparent toner is used for the toner adhesion amount detection pattern 9 so as to obtain an appropriate transfer condition in each case, it is not performed. Set separately.
This makes it possible to obtain appropriate transfer conditions for each of the modes in which the transparent toner is used or not, in which the transfer condition varies depending on whether the image is formed with only the colored toner or when the transparent toner is used. When the transparent toner is used, the adhesion amounts of the toner adhesion amount detection patterns 91 and 92 are detected by the color toner and the transparent toner, and the transfer current is adjusted only when the transparent toner is used. The transfer current may be adjusted for each recording medium 6, or the image forming area in the transport direction is divided into a plurality of parts in one recording medium 6, and the transfer current is changed in real time for each part. You may do as follows.

  By adjusting the transfer current described above, the transfer conditions change when an image is formed only with colored toner in a mode using transparent toner and when an image is formed with transparent toner and colored toner. The transfer current can be set based on the result of detection of the detection patterns 91 and 92 by the toner adhesion amount detection unit 67.

  In addition, the toner adhesion amount detection unit 68 is prepared after the image is transferred to the recording medium 6 and before the toner image remaining on the intermediate transfer belt 61 is cleaned, and the image forming condition is set based on the detection result of the toner adhesion amount. To do. Thereby, the versatility of the recording medium 6 is expanded. By selecting the transfer current from the result of taking the transfer state of the recording medium 6 into consideration, it is possible to obtain a good transfer property corresponding to each recording medium. The transferability of the image greatly depends on the characteristics of the recording medium 6. By detecting the amount of adhesion before and after transfer, the amount of transfer to the recording medium 6 can be determined from the difference between the amounts detected. That is, the transfer amount with respect to the passed paper is known. If the detection is made for each paper having different characteristics, the transfer amount for each paper can be known, so that it is possible to set transfer conditions corresponding to the difference in the characteristics of the paper.

6, 7 and 8 are schematic views of cross-sectional views of the color toner and the transparent toner on the intermediate transfer belt and the recording medium.
A toner adhesion amount detection unit 67 formed on the intermediate transfer belt 61 so as to face the recording medium 6 or a toner adhesion amount detection unit 68 provided so as to face the intermediate transfer belt 61 downstream from the secondary transfer position. Thus, the adhesion amounts of the toner adhesion amount detection patterns 91 and 92 are detected. The toner adhesion amount detection patterns 91 and 92 are provided only in a region that passes the reading position of the toner adhesion amount detection units 67 and 68.

FIG. 6 is a schematic diagram of cross-sectional views of the color toner and the transparent toner and the recording medium on the intermediate transfer belt in the conventional apparatus. In the conventional detection method using a detection pattern, a transparent toner adhesion amount detection pattern 92 is formed on the intermediate transfer belt 61 so as to overlap with a color toner adhesion amount detection pattern 91 read by the toner adhesion amount detection units 67 and 68. The images are transferred onto the recording medium 6 in a superimposed manner.
In this case, the resistance difference is greatly different between the toner adhesion amount detection patterns 91 and 92 of the overlapping patches and the portions other than the patch patterns. When the transfer amount is set by detecting the toner adhesion amount of the pattern formed in this way, the transparent toner is transferred onto a part of the recording medium 6 (for example, the transparent toner in the form of characters to be printed is placed). The transfer condition corresponding to is set. Accordingly, in an image of only colored toner that is not developed with transparent toner, the transfer current value is high, and the toner is scattered due to a burst phenomenon, and characters may be fainted or an abnormal image may occur due to fogging on a white background.

FIG. 7 is a schematic diagram illustrating an example of a cross-sectional structure of the intermediate transfer belt, the color toner / transparent toner, and the recording medium in the present embodiment. Therefore, here, the form of toner to be transferred in the image forming apparatus 1 of the present embodiment is shown.
As shown in FIG. 7, in the image forming apparatus 1 according to the present embodiment, the toner adhesion amount detection pattern 91 of the colored toner is applied to the recording medium 6 or the photosensitive member 11 in the width direction part of the main scanning direction. The toner adhesion amount detection pattern 92 is formed wider than the color toner adhesion amount detection pattern 91.
Therefore, the overlapping state of the colored toner and the transparent toner is different from that in FIG. As shown in FIG. 7, superimposing the toner adhesion amount detection pattern 92 of transparent toner on the toner adhesion amount detection pattern 91 of color toner is the same as in FIG. 6, but in FIG. In FIG. 7, there is a transparent toner region where only the transparent toner is developed.
Therefore, comparing FIG. 6 and FIG. 7, the difference in transfer current between the single portion of the colored toner and the overlapping portion of the colored toner and the transparent toner is different between the portion where the toner is not present, the colored toner and the transparent toner. This is smaller than the transfer current at the overlapping portion.
Therefore, if a single portion of colored toner and a pattern of overlapping portions where the colored toner and transparent toner overlap are formed, the amount of adhesion of each portion is detected, and the transfer condition is set based on the amount of adhesion, the main scanning It is possible to set a transfer condition suitable for the use form such that the transparent toner is transferred widely in the direction.
In particular, in the example shown in FIG. 7, in the image forming apparatus 1 of the present invention, the colored toner pattern is formed on the recording medium 6 or a part of the width direction that is the main scanning direction of the photoconductor 11 over the entire image forming area. The formation area of the colored toner varies depending on the image, but the transparent toner is formed on the entire area of the recording medium 6 or the photoreceptor 11 regardless of the image. Therefore, the image forming apparatus 1 that forms a pattern over the entire width is particularly effective. In this case, it is possible to set a transfer condition suitable for the use form such that the transparent toner is transferred to the entire image forming area.

FIG. 8 is a schematic diagram illustrating another example of the cross-sectional structure of the intermediate transfer belt, the color toner / transparent toner, and the recording medium according to the present exemplary embodiment.
When detecting the toner adhesion amount, an appropriate transfer bias varies depending on the width in the main scanning direction. For example, as shown in FIG. 8, the recording medium 6 is an example having a small width in the main scanning direction.
At this time, the transfer bias of the secondary transfer roller 63 requires a large amount of applied voltage because a large amount of current flows from the secondary transfer roller 63 in a portion where the recording medium 6 is not present in the main scanning direction where the resistance is low.
A toner adhering amount detection pattern 92 of transparent toner corresponding to the output image is attached to the main scanning width, and an appropriate transfer bias condition of the secondary transfer roller 63 is selected. As described above, the toner adhesion amount detection patterns 91 and 92 are formed in the overlapping portion where the color toner and the transparent toner overlap each other when the width of the image forming region in the main scanning direction is small. If the transfer amount is detected and the transfer condition is set based on the adhesion amount, the transfer condition suitable for the use form such that the transparent toner is transferred to the entire image forming area can be set.

  FIG. 9 is a block diagram illustrating an example of a main configuration of a control system in the image forming apparatus according to the present embodiment. The control unit 900 includes, for example, a CPU 901, a RAM 902, a ROM 903, an I / O interface 904, and the like. Further, the control unit 900 is connected to the control target portion of the image forming units 10Tr, 10Y, 10C, 10M, and 10K via the I / O interface 904. Furthermore, the control unit 900 applies predetermined transfer biases to the toner adhesion amount detection units 67 and 68, the primary transfer rollers 62Tr, 62Y, 62C, 62M, and 62K and the secondary transfer roller 63 via the I / O interface 904. It is connected to a bias power source 910 to be applied, a temperature / humidity sensor 920 for detecting a use environment such as temperature and humidity as a use environment recognition means. The control unit 900 executes a predetermined control program incorporated in advance, so that the primary transfer bias output from the bias power source 910 is detected based on the detection results of the toner adhesion amount detection units 67 and 68 and the temperature / humidity sensor 920. Various image forming conditions including transfer conditions such as setting a secondary transfer bias can be changed. Further, the control unit 900 can control each unit in the image forming unit 10 including toner pattern formation and transfer bias application during an image forming operation by executing a predetermined control program.

  As described above, the control unit 900 detects the toner adhesion amount on the intermediate transfer belt 61 and performs image quality adjustment by controlling image forming conditions such as transfer conditions based on the detection result. At this time, when the recording medium 6 does not pass through the secondary transfer portion, the toner adhesion amount detection pattern 9 formed on the intermediate transfer belt 61 is transferred to the secondary transfer roller 63, and then the secondary transfer. There is a risk that quality may be deteriorated such that the toner adheres to the recording medium 6 that has passed through the portion and stains occur. Therefore, a cleaning bias may be applied between the secondary transfer roller 63 and the intermediate transfer belt 61 so that the toner on the secondary transfer roller 63 is peeled off from the roller. By applying a cleaning bias between the secondary transfer roller 63 and the intermediate transfer belt 61, the toner on the secondary transfer roller 63 is transferred to the intermediate transfer belt 61, and the surface of the secondary transfer roller 63 is cleaned. be able to. Contamination such as toner on the intermediate transfer belt 61 transferred from the secondary transfer roller 63 is cleaned by the belt cleaning device 64. Since dirt such as toner remaining on the secondary transfer roller 63 after cleaning is cleaned by the cleaning blade 22, the dirt on the secondary transfer roller 63 can be reliably cleaned.

  When the cleaning bias is applied, when the color toner and the transparent toner are used in combination, more toner is transferred to the secondary transfer roller 63 than when only the color toner is used. Therefore, the cleaning conditions may be changed. For example, by changing the cleaning bias applied to the secondary transfer roller 63 and the intermediate transfer belt 61 when using both colored toner and transparent toner and when using only colored toner, Cleaning can be performed at an appropriate value. More specifically, when the color toner and the transparent toner are used together, the applied cleaning bias is increased as compared with the case where only the color toner is used. As a result, more toner can be cleaned from the secondary transfer roller 63. On the other hand, when only colored toner is used, the cleaning bias to be applied can be reduced and the current is not supplied more than necessary, so that the durability of the secondary transfer roller 63 can be improved.

  Further, at a necessary timing, a constant cleaning bias is applied between the secondary transfer roller 63 and the intermediate transfer belt 61 so that the toner attached to the secondary transfer roller 63 is transferred to the intermediate transfer belt 61 side. You may set the cleaning mode which carries out time idle. Thereby, the dirt of the secondary transfer roller 63 can be removed. At this time, the application bias and the idling time applied to the secondary transfer roller 63 and the intermediate transfer belt 61 are variably set depending on whether only the color toner is used or when the color toner and the transparent toner are used. The dirt on the secondary transfer roller 63 may be removed. For example, when the color toner and the transparent toner are used together, the cleaning bias to be applied is increased or the idling time is increased as compared with the case where only the color toner is used.

  Note that when the cleaning bias is applied to the secondary transfer roller 63 and the intermediate transfer belt 61, the cleaning bias may be applied to the cleaning blade 22 at the same time. Accordingly, the secondary transfer roller 63 can be cleaned by the intermediate transfer belt 61 and the cleaning blade 22, and can be cleaned more quickly and more reliably. Further, the secondary transfer roller 63 may be cleaned only by the cleaning blade 22, and the load on the intermediate transfer belt 61 can be reduced.

FIG. 10 is a schematic diagram showing a recording medium on the intermediate transfer belt and a transparent toner image formed at the leading end in the transport direction. In the drawing, a portion 90 ′ displayed in gray in the image portion 90 corresponding to the recording medium 6 is a colored toner portion, and a portion 90 ″ displayed in white is a transparent toner portion.
Usually, as a configuration for stabilizing the friction coefficient of the intermediate transfer belt 61, a lubricant application device 45 is provided, and the belt cleaning device 64 is configured using a cleaning blade 642.
In a high-temperature and high-humidity environment, there is a concern that the productivity may be lowered due to the cleaning blade 642 coming into contact with the intermediate transfer belt 61 having a high friction coefficient turned up. This phenomenon is likely to occur particularly in the small-sized recording medium 6. In a low-temperature and low-humidity environment, there is a risk of paper separation failure due to electrostatic force acting on the recording medium 6 and the intermediate transfer belt 61 due to transfer bias application during secondary transfer.
Therefore, if the toner adhesion amount detection pattern 92 of the transparent toner is formed at the leading end portion of the recording medium 6 in the main scanning direction larger than the width of the recording medium 6 as shown in FIG. Since the toner is formed of transparent toner, there is no possibility that the recording medium 6 picks up toner stains in the image forming apparatus 1.
That is, in a low-temperature and low-humidity environment, as shown in FIG. 10, the toner adhesion amount detection pattern 92 of the transparent toner is formed at the conveyance leading end portion of the recording medium 6, thereby reducing the electrostatic force at the time of secondary transfer and achieving good transfer. And sheet separation can be obtained. Further, even when an image is formed on a small-sized recording medium 6 in a high-temperature and high-humidity environment, a transparent toner adhering amount detection pattern 92 is formed at the conveyance leading end of the recording medium 6 so that it passes through the secondary transfer section. Thus, the transparent toner cleaned by the belt cleaning device 64 can reduce the frictional force between the intermediate transfer belt 61 and the cleaning blade 642, thereby avoiding blade turning.

What has been described above is merely an example, and the present invention has a specific effect for each of the following modes.
(Aspect A)
A toner image obtained by forming a latent image on an image carrier such as the photoreceptor 11 and developing the latent image with only the color toner or both the color toner and the transparent toner is used as an intermediate transfer belt 61 or the like. Image formation in which an image is formed on the recording medium 6 by transferring the toner image transferred onto the transfer member and transferring onto the recording medium 6 such as paper, and fixing the toner image by applying heat. The apparatus 1 includes a toner adhesion amount detection unit 67 that detects the toner adhesion amount on the intermediate transfer member, and a control unit 900 that controls image forming conditions based on the detection result of the toner adhesion amount detection unit 67. When an image is formed with only toner, a color toner adhesion amount detection pattern 91 is formed. When an image is formed with both color toner and transparent toner, a color toner adhesion amount detection pattern is formed. Forming one and the toner adhesion amount detection pattern 92 of the transparent toner. According to this, as described in the above embodiment, when an image is formed with only colored toner, the toner adhesion amount of the color toner adhesion amount detection pattern 91 is detected by the toner adhesion amount detection unit 67, and the detection result Based on the above, the control unit 900 controls image forming conditions such as transfer conditions. Further, when an image is formed with both colored toner and transparent toner, the toner adhesion amount detection unit 67 determines the toner adhesion amount of the portion where the toner adhesion amount detection patterns 91 and 92 formed with both the color toner and the transparent toner are superimposed. Based on the detection result, the control unit 900 controls image forming conditions such as transfer conditions. As a result, even when a transparent toner is used, good transferability can be obtained as in the case of a toner image formed only with colored toner.
(Aspect B)
In the above aspect A, the toner adhesion amount detection pattern 92 formed of transparent toner so that the formation area of the toner adhesion amount detection pattern 92 formed of transparent toner includes the formation area of the toner adhesion amount detection pattern 91 formed of colored toner. The width in the main scanning direction is made wider than the width in the main scanning direction of the toner adhesion amount detection pattern 91 formed of colored toner. When transparent toner is used, transfer conditions are different from when transparent toner is not used. In particular, since the transparent toner is often used to give gloss to the surface of the recording medium 6, it is often formed in a wider area on the recording medium 6 than the colored toner. Therefore, the transparent toner adhesion amount detection pattern 92 is formed so that the width of the transparent toner adhesion amount detection pattern 92 is wider than the width of the colored toner adhesion amount detection pattern 91 in the main scanning direction. As a result, it is possible to set an optimum transfer condition for image formation suitable for the usage pattern in which the transparent toner is transferred to the entire area of the image formation area.
(Aspect C)
In the above-described aspect A or B, when forming an image using transparent toner, the toner adhesion amount detection unit 67 uses the toner adhesion amount in the toner adhesion amount detection patterns 91 and 92 formed of both colored toner and transparent toner. Based on the detection result of the toner adhesion amount detection unit 67, the control unit 900 controls the transfer conditions when transferring the toner image formed of both the transparent toner and the color toner to the recording medium 6. According to this, when the transparent toner is used, the adhesion amount of the toner adhesion amount detection patterns 91 and 92 is detected for each recording medium 6 with the color toner and the transparent toner, and the transfer condition (only when the transparent toner is used) For example, it is possible to adjust a transfer bias voltage and a transfer current. Therefore, the transfer conditions when using the transparent toner can be adjusted, and better transferability can be obtained.
The transfer conditions (for example, transfer bias voltage and transfer current) can be adjusted for each recording medium 6, that is, for each image forming area corresponding to the recording medium 6. Further, in the image forming region on the intermediate transfer member such as the intermediate transfer belt 61, when the optimum transfer conditions (for example, the voltage of the transfer bias and the transfer current) are partially different in the surface movement direction of the intermediate transfer member, The above transfer conditions (for example, transfer bias voltage and transfer current) may be adjusted so as to be changed in real time during the transfer process in which the toner image is transferred to one recording medium 6.
(Aspect D)
In any one of the above aspects A to C, the toner adhesion amount detection unit 68 transfers the image from the intermediate transfer member such as the intermediate transfer belt 61 to the recording medium 6 and remains on the intermediate transfer member. The toner adhesion amount on the intermediate transfer member before cleaning the image is detected, and the control unit 900 forms an image based on the detection result of the toner adhesion amount on the intermediate transfer member after the transfer and before cleaning. Set conditions. According to this, the versatility of the recording medium 6 on which an image is formed can be expanded. Although the image transferability greatly depends on the characteristics of the recording medium 6, the transfer state to the recording medium 6 can be determined by detecting the toner adhesion amount on the intermediate transfer member after the transfer to the recording medium 6. By setting the transfer conditions (for example, the voltage of the transfer bias and the magnitude of the transfer current) in consideration of the state, it is possible to obtain good transfer properties according to the various recording media. The toner adhesion amount detection unit 67 detects the toner adhesion amount before transfer, and the toner adhesion amount detection unit 68 detects the adhesion amount after transfer, so that the transfer amount to the recording medium 6 can be determined from the difference between the two detection amounts. I understand. That is, the transfer amount with respect to the recording medium 6 that has passed the paper is known. If detection is performed for each recording medium 6 having different characteristics, the transfer amount for each recording medium 6 can be known, so that transfer conditions corresponding to the differences in characteristics of the recording medium 6 can be set.
(Aspect E)
In any of the above aspects A to D, the toner image transferred onto the intermediate transfer member such as the intermediate transfer belt 61 is opposed to the intermediate transfer member at a transfer unit such as a secondary transfer unit that transfers the toner image to the recording medium 6. And a counter member such as the secondary transfer roller 63 disposed so as to perform cleaning, and a cleaning unit for cleaning the surface of the counter member (a unit also serving as an intermediate transfer member or a separate cleaning blade 22). The cleaning condition (for example, the cleaning bias application condition) of the cleaning unit is changed between when the image is formed using only the color toner and when the image is formed using both the color toner and the transparent toner. According to this, when a cleaning bias is applied between the facing member such as the secondary transfer roller 63 and the intermediate transfer member such as the intermediate transfer belt 61, when both the color toner and the transparent toner are used, the color toner is used. When using only the cleaning roller, it is possible to change the cleaning condition such as the application condition of the cleaning bias and clean the surface of the opposing member such as the secondary transfer roller 63 under the appropriate cleaning condition. Accordingly, it is possible to clean the toner and the like adhering to the opposing member such as the secondary transfer roller 63, and to improve the durability of the opposing member such as the secondary transfer roller 63 by not energizing more than necessary. Can do.
(Aspect F)
In any of the above aspects A to E, when a transparent toner is used, a toner adhesion amount detection pattern 92 formed with the transparent toner is formed over the entire width of the image forming area. According to this, it is possible to set a transfer condition suitable for the use form such that the transparent toner is transferred over the entire image forming area width. Also, when transferring transparent toner over the entire image forming area width, the transfer current is almost constant over the entire image forming area width, compared to when transferring transparent toner over a part of the image forming area width. Can be maintained, and better transferability can be obtained.
(Aspect G)
In the aspect F, the formation width of the toner adhesion amount detection pattern 92 formed of transparent toner is changed according to the width of the recording medium 6 onto which an image is transferred from an intermediate transfer member such as the intermediate transfer belt 61. When the width of the recording medium 6 in the main scanning direction is smaller than the width of the intermediate transfer member, the resistance of the intermediate transfer member in the main scanning direction when the transfer bias is applied to the opposing member such as the secondary transfer roller 63. Since a large amount of current from the facing member flows in a small portion (portion where the recording medium 6 is not present), a necessary transfer bias voltage is increased. As described above, by applying the transparent toner in the main scanning direction according to the width of the recording medium 6 (the width of the output image), an appropriate transfer bias condition to be applied to the opposing member such as the secondary transfer roller 63 is selected. can do.
(Aspect H)
In any one of the above aspects A to G, the image forming apparatus 1 includes use environment recognition means such as a temperature and humidity sensor that recognizes the use environment, and the control unit 900 recognizes the use environment such as the temperature and humidity sensor 920. Based on the recognition result of the means, optimum transfer conditions are set. According to this, it is possible to set an optimal transfer condition according to the use environment and perform good transfer from the intermediate transfer member such as the intermediate transfer belt 61 to the recording medium 6.
(Aspect I)
In the aspect H, the image forming apparatus 1 uses the transparent toner to detect the toner adhesion amount detection pattern based on the recognition result of the use environment recognition unit such as the temperature / humidity sensor 920 and at least one of the material and size of the recording medium 6. The width 92 of the main scanning direction is set to be equal to or larger than the width of the recording medium 6 to form the toner adhesion amount detection pattern 92. The adhesion amount detection pattern 92 of the transparent toner formed on the intermediate transfer member such as the intermediate transfer belt 61 is not transferred to the recording medium 6 and remains on the intermediate transfer member. The remaining transparent toner can reduce the frictional force between the intermediate transfer member and the cleaning blade 642 in a high-temperature and high-humidity environment, avoid the turning-up of the cleaning blade 642, and prevent a decrease in productivity. . Further, by forming the toner adhesion amount detection pattern 92 of the transparent toner in the vicinity of the conveyance leading end portion of the recording medium 6 on the intermediate transfer member such as the intermediate transfer belt 61, good transfer property and paper separation property can be obtained. Is possible.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Paper feed part 3 Image forming part 4 Image reading apparatus (scanner part)
5 Automatic document feeder (ADF)
6 Recording medium 7 Document 9 Toner adhesion amount detection pattern 91 Color toner adhesion amount detection pattern 92 Transparent toner adhesion amount detection pattern 10 Image forming unit (process cartridge)
DESCRIPTION OF SYMBOLS 11 Photoconductor 12 Exposure apparatus 13 Static elimination apparatus 20 Charging apparatus 21 Charging roller 22 Cleaning blade 30 of a secondary transfer roller Developing apparatus 40 Cleaning apparatus 45 Lubricant coating apparatus 60 Transfer apparatus 61 Intermediate transfer belt 62 Primary transfer roller 63 Secondary transfer roller 631 Secondary transfer counter roller 632 Guide roller 64 Belt cleaning device 641 Cleaning backup roller 642 Cleaning blade 65 Roller 651 Drive roller 652 Driven roller 653 External stretch roller Support / tension roller 66 Conveyor belt 67, 68 Toner adhesion amount detection unit 70 Fixing Device 80 Paper feed device 81 Paper feed cassette 811 Separating roller 812 Paper feed roller 82 Transport path 83a, 83b, 83c, 83d Transport roller 84 Registration roller 85 Paper discharge low 851, 852 switching claw 86 discharge tray 87 reverse transport path 88 recording medium accommodating apparatus 89 recording medium inversion conveyor 900 controller 910 bias power source 920 temperature and humidity sensor

JP 2009-168906 A

Claims (9)

A latent image is formed on the image carrier, and a toner image obtained by developing the latent image with only colored toner or with both colored toner and transparent toner is transferred to an intermediate transfer member,
In the image forming apparatus for forming an image on the recording medium by transferring the toner image transferred onto the intermediate transfer member to a recording medium and fixing the toner image by applying heat.
Based on the detection result of the means for forming the toner adhesion amount detection pattern on the intermediate transfer member, the toner adhesion amount detection unit for detecting the toner adhesion amount on the intermediate transfer member, and the detection result of the toner adhesion amount detection unit A control unit for controlling the conditions,
When forming an image with only the colored toner, a toner adhesion amount detection pattern is formed with the colored toner,
An image forming apparatus, wherein when an image is formed using both the color toner and the transparent toner, a toner adhesion amount detection pattern is formed using both the color toner and the transparent toner. The image forming apparatus according to claim 1.
In the main scanning direction of the toner adhesion amount detection pattern formed with the transparent toner, the formation area of the toner adhesion amount detection pattern formed with the transparent toner includes the formation area of the toner adhesion amount detection pattern formed with the colored toner. An image forming apparatus, wherein the width is wider than the width in the main scanning direction of the toner adhesion amount detection pattern formed of the color toner. The image forming apparatus according to claim 1, wherein
When forming an image using the transparent toner, the toner adhesion amount detection unit detects a toner adhesion amount in a toner adhesion amount detection pattern formed of both the colored toner and the transparent toner, and the control unit The image forming apparatus controls transfer conditions for transferring a toner image formed of both the transparent toner and the colored toner to a recording medium based on a detection result of the toner adhesion amount detection unit. . The image forming apparatus according to any one of claims 1 to 3,
The toner adhesion amount detection unit detects the toner adhesion amount on the intermediate transfer member after the image is transferred from the intermediate transfer member to the recording medium and before the toner image remaining on the intermediate transfer member is cleaned. And
The image forming apparatus, wherein the control unit sets an image forming condition based on a detection result of a toner adhesion amount on the intermediate transfer member after the transfer and before cleaning. The image forming apparatus according to claim 1,
A facing member disposed to face the intermediate transfer member at a transfer portion for transferring the toner image transferred onto the intermediate transfer member to a recording medium;
Cleaning means for cleaning the surface of the opposing member facing the intermediate transfer member;
An image forming apparatus, wherein the cleaning condition of the cleaning unit is changed when an image is formed with only the color toner and when an image is formed with both the color toner and the transparent toner. The image forming apparatus according to claim 1,
An image forming apparatus, wherein when the transparent toner is used, a toner adhesion amount detection pattern formed with the transparent toner is formed over the entire width of the image forming area. The image forming apparatus according to claim 6.
An image forming apparatus, wherein a formation width of a toner adhesion amount detection pattern formed with the transparent toner is changed according to a width of a recording medium onto which an image is transferred from the intermediate transfer member. The image forming apparatus according to claim 1,
Use environment recognition means to recognize the use environment,
The image forming apparatus, wherein the control unit sets an optimum transfer condition based on a recognition result of the use environment recognition unit. The image forming apparatus according to claim 8.
Based on the recognition result of the use environment recognition means and at least one of the material and size of the recording medium, the width in the main scanning direction of the toner adhesion amount detection pattern formed of the transparent toner is set to be equal to or larger than the width of the recording medium. An image forming apparatus that forms the toner adhesion amount detection pattern.

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