JP2007148145A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of preventing the adhesion of a foreign matter to an image carrier and an abnormal image caused thereby by uniformly lowering the surface energy of an image carrier (photoreceptor) with minimum toner consumption even when a document where high image area and low image area are unevenly distributed is output consecutively. <P>SOLUTION: The image forming apparatus is provided with: the image carrier 14; an exposure unit 16 forming an electrostatic latent image on the image carrier 14; and a developing unit 13 developing the electrostatic latent image on the image carrier 14 by using developer. It is provided with an image information calculation means for calculating image information of each of regions divided into plurality in a direction orthogonal to the rotating direction of the image carrier 14, so that exposure and development are performed independently of image formation in each region based on the image information of each region. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention repeatedly forms a toner image on an image carrier by repeating charging, writing, development, transfer, cleaning, static elimination, and the like, and sequentially transfers the toner image and records it on a transfer sheet such as paper or an OHP film. The present invention relates to an electrophotographic image forming apparatus such as a copying machine, a printer, a facsimile, or a complex machine thereof.

Conventionally, in this type of electrophotographic image forming apparatus, an organic photoreceptor formed by using an organic photosensitive material because it is inexpensive, suitable for mass production, and does not cause pollution. Is widely used.
However, the organic photoreceptor has the disadvantages that the abrasion resistance is low and the durability is inferior compared to the inorganic photoreceptor. Particularly in recent years, there has been a strong demand for downsizing of image forming apparatuses, and the downsizing of photoconductors is inevitable, and it is strongly desired to improve wear resistance and improve mechanical durability. For this reason, various technologies corresponding to this have been proposed (see, for example, Patent Documents 1 to 6).
A conventional image forming apparatus contains a filler made of a metal or a metal oxide on the surface of the organic photoreceptor, as described in Patent Document 1, for example, in order to increase the wear resistance of the organic photoreceptor. A technique for providing a protective layer is disclosed.
However, when the protective layer is provided on the surface of the organic photoreceptor in this manner, the surface energy of the photoreceptor increases with time, the transfer rate may decrease, and an abnormal image such as a transfer defect may occur. there were.
For this reason, while providing a protective layer on the surface of the organic photoreceptor, for example, as described in Patent Document 2, a solid lubricant is applied using an application means such as a brush, or in Patent Documents 3 and 4. As described above, a technique is disclosed in which a lubricant is externally added to a toner and supplied to a photoreceptor.
However, supplying the lubricant reduces the surface energy of the photoconductor, reduces the wear of the photoconductor, prevents foreign matter from adhering to the photoconductor, and prevents the occurrence of abnormal images such as transfer loss. I was doing.
In addition, as described in Patent Document 5, there is a technique of providing an image area calculation unit for an image formed on an image carrier and supplying a lubricant according to the calculation result. This is because when the images of low image area are continuous, the toner supply to the photoconductor is small and the surface energy of the photoconductor is reduced, so that the image area is less than a predetermined value by the image area calculation means The toner is supplied after development.
However, in recent years, especially in color printers, the opportunity to be used for outputting presentation materials and the like has increased, and there are many cases of outputting a large amount of documents mixed with figures and photographs.

FIG. 12 is a schematic view showing photographs and figures arranged in the left half of the document and characters arranged in the right half. In addition, the format of these documents with a mixture of figures and photos is often determined. For example, as shown in FIG. 12, photographs and figures are arranged on the left half of the document, and characters are arranged on the right half. In some cases, these documents are output continuously.
When a document in which such a portion having a high image area and a portion having a low image area are continuously output, toner is always supplied to the photosensitive member corresponding to the left half of the document. The toner on the portion corresponding to the right half of the document is not supplied with much toner, resulting in a difference in the surface state of the photoconductor.
In particular, when the developer contains a lubricant, there is a large difference in the amount of lubricant applied to the photoreceptor between the portion corresponding to the left half of the document and the portion corresponding to the right half. Problems caused by the insufficient amount of lubricant applied include toner, additives, and paper dust on the surface of the photoconductor that adhere to a thin film. For example, an abnormal image such as a void is generated. In order to suppress these, it is important to apply the lubricant uniformly on the surface of the photoreceptor.
In Patent Document 5, the lubricant is applied in accordance with the image area. However, in the case of a document in which a high image area ratio portion and a low image area ratio portion are unevenly distributed as shown in FIG. Even if the image area ratio as a whole is not low, a defect may partially occur on the photoconductor.
Patent Document 6 includes a calculation unit that calculates an image area ratio for each area by dividing the image carrier into a plurality of areas in a direction perpendicular to the developer conveyance direction of the image carrier. A technique is disclosed in which a minimum image area rate is compared with a predetermined image area reference rate, and a solid image is formed on the entire screen according to the comparison result.
JP-A-1-170951 JP 2000-162881 A Japanese Patent No. 2859646 JP 2002-229241 A JP 2003-241570 A JP 2000-221769 A

However, if solid formation is performed on the entire screen, the toner consumption increases. Since an increase in toner consumption directly leads to an increase in CPP (cost per print), it is necessary to suppress toner consumption as much as possible.
In Patent Document 6, solid formation is performed for the purpose of preventing unevenness in image density due to uneven charge amount of toner on the developing sleeve. However, the purpose of applying lubricant to a photosensitive member by adding a lubricant to the developer is described. The same applies to the case.
Even when the toner charge amount variation and the unevenness of the lubricant coating on the surface of the photoreceptor can be made uniform by partial toner supply, since the entire surface is formed with solid toner, the amount of toner consumption increases when the toner is formed too frequently. There is a problem of end. Therefore, in order to suppress CPP (cost per print) which is very important for the user, there is still room for improvement from the viewpoint of reducing toner consumption.
On the other hand, when calculating the image information for each area of the image carrier, in order to accurately calculate the information of the image formed, the area is divided in the direction perpendicular to the transport direction and the exposure for each area is performed. It is sufficient to count the number of pixels. However, counting and storing pixel information that is continuously output at a high speed for each of many areas is a load at the time of image output.
In addition, more accurate image information can be obtained by detecting whether there is a solid image in the output image, but in order to determine the presence or absence of a solid image, not only the scanning direction during exposure but also It is necessary to store pixel information in the sub-scanning direction, and it takes physical time to store these in the memory individually in each area during continuous output. As color printers increase in speed, it is important to achieve high durability of the image carrier (photosensitive member) and to reduce toner consumption by obtaining accurate image information with as little load as possible.

Accordingly, an object of the present invention is to uniformize the surface energy of an image carrier (photoreceptor) with a minimum amount of toner consumption even when a document in which a high image area and a low image area are unevenly distributed is output continuously. It is an object of the present invention to provide an image forming apparatus that can prevent the adhesion of foreign matters to an image carrier and the occurrence of abnormal images associated therewith.
Another object of the present invention is to minimize toner consumption without imposing a load on the print output as much as possible even when a document in which a high image area and a low image area are unevenly output is output continuously. An object of the present invention is to provide an image forming apparatus capable of reducing the surface energy of a photoreceptor uniformly, preventing foreign matter from adhering to an image carrier (photoreceptor) and accompanying abnormal images, and capable of high-speed output.

In order to solve the above-described problems, an invention according to claim 1 is directed to an image carrier, an exposure unit for forming an electrostatic latent image on the image carrier, and a developer. An image forming apparatus comprising: a developing unit that develops an electrostatic latent image; and an image information calculating unit that calculates image information for each of a plurality of divided areas in a direction orthogonal to a rotation direction of the image carrier. An image forming apparatus that performs exposure and development separately from image formation for each region based on image information for each region.
According to a second aspect of the present invention, the image information calculating means calculates the image area information relative to the traveling area.
According to a third aspect of the present invention, there is provided an image carrier, an exposure unit for forming an electrostatic latent image on the image carrier, and development for developing the electrostatic latent image on the image carrier using a developer. An image information calculating means for calculating image information for each of a plurality of areas divided in a direction orthogonal to the rotation direction of the image carrier, and an average image information of each area And an image forming apparatus that performs exposure and development separately from image formation.
According to a fourth aspect of the present invention, there is provided an image carrier, an exposure unit for forming an electrostatic latent image on the image carrier, and development for developing the electrostatic latent image on the image carrier using a developer. An image forming apparatus comprising: a unit; and an image information calculating unit that calculates image information for each of a plurality of regions divided in a direction orthogonal to a rotation direction of the image carrier. The image forming apparatus calculates image information of each region from a photosensor arranged on the image carrier in a direction perpendicular to the rotation direction.
According to a fifth aspect of the present invention, the image information calculation means calculates image information of each region from a photosensor disposed on an intermediate transfer body that primarily transfers toner developed on the image carrier. The image forming apparatus according to claim 4 is characterized.
According to a sixth aspect of the present invention, in the image forming apparatus according to the fourth aspect, the image information calculating unit calculates the image information of each region from a photosensor arranged on the transfer paper in a direction orthogonal to the transport direction. Features.
According to a seventh aspect of the invention, there is provided the image forming apparatus according to any one of the first to sixth aspects, wherein the developer contains a lubricant.
According to an eighth aspect of the invention, there is provided an image forming apparatus according to any one of the first to seventh aspects, further comprising a cleaning device that removes toner remaining on the image carrier with a cleaning blade.
The invention according to claim 9 is an image according to any one of claims 1 to 8, wherein an organic photoreceptor is used as the image carrier, and a protective layer containing a filler is provided on the surface of the organic photoreceptor. Features a forming device.

According to the present invention, the image carrier is divided into a plurality of regions, and toner is supplied to each region of the image carrier separately from development for image formation, regardless of the size of the image area ratio. The surface state of the image carrier and the toner charge amount on the developing sleeve can be averaged even for a document in which the image area ratio is unevenly distributed. It is possible to provide an image forming apparatus that suppresses the occurrence of abnormal images to improve the durability of the image carrier and suppresses toner consumption as much as possible.
In addition, the image carrier is divided into a plurality of regions, and toner is supplied to each region of the image carrier separately from the development for image formation. The surface state of the image carrier and the toner charge amount on the developing sleeve can be averaged even for documents with uneven sizes.
Furthermore, the image area ratio is calculated from the image information read by a plurality of photosensors arranged on the image carrier in the direction orthogonal to the rotation direction, and the image information can be calculated without imposing a load on the memory. It is possible to cope with the speeding up of the printer, and it is possible to improve the durability of the image carrier and reduce the toner consumption even in a high-speed output printer.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic diagram showing the overall configuration of a small color printer as an example of an image forming apparatus according to the present invention. In the figure, reference numeral A denotes a printer main body. In the apparatus main body A, a transfer paper conveyance path P is provided obliquely from the lower right to the upper left in the drawing.
On the transfer paper conveyance path P, four monochrome image forming means 10Y, 10M, 10C, and 10B of yellow, magenta, cyan, and black are arranged in order from the lower right to the upper left along the conveyance path P to form a tandem type. I have.
Each monochromatic image forming means 10 includes image carrier units 12Y, 12M, 12C, and 12B and developing units 13Y, 13M, 13C, and 13B, and is detachable from the apparatus main body A. Each image carrier unit, which will be described in detail later, is provided with drum-shaped image carriers 14Y, 14M, 14C, and 14B, respectively. On such monochromatic image forming means 10Y, 10M, 10C, 10B, along with the monochromatic image forming means 10, a writing unit 16 described later in detail is provided obliquely.
On the other hand, an endless belt-shaped transfer paper carrier 18 is stretched under the monochromatic image forming means 10Y, 10M, 10C, and 10B with the transfer paper conveyance path P interposed therebetween. In the illustrated example, the transfer paper carrier 18 is wound around four support rollers 19 and is in contact with the image carriers 14Y, 14M, 14C, and 14B, and a part thereof is provided along the transfer paper conveyance path P. A non-driving device can be rotated and conveyed counterclockwise in the figure.
Inside the transfer paper carrier 18, backup rollers 20Y, 20M, 20C, and 20B and transfer brushes 21Y, 21M, 21C, and 21B are arranged corresponding to the image carriers 14Y, 14M, 14C, and 14B, respectively. ing. The backup rollers 20Y, 20M, 20C, and 20B bring the transfer paper carrier 18 and the transfer paper into close contact with the image carriers 14Y, 14M, 14C, and 14B.
The transfer brushes 21Y, 21M, 21C, and 21B are supplied with a transfer bias from a power source (not shown). In the illustrated example, it is a transfer brush, but it may be a non-contact charger.
A registration roller pair 23 is provided along the transfer paper conveyance path P at the upstream position of the transfer paper carrier 18, and a fixing unit 24 is provided at the downstream position. The fixing unit 24 is configured by pressing a pressure roller 26 against a fixing belt 25 that is an endless belt, and a discharge roller pair 27 at an outlet.

A reversing unit 29 is provided downstream of the fixing unit 24 and attached to the apparatus main body A. The reversing unit 29 discharges the transfer paper as it is, reverses and discharges it, or returns it to the apparatus main body A again.
Further, a reverse paper discharge path P1 is formed at a downstream position of the fixing unit 24 from the transfer paper transport path P, and the transfer paper is discharged to the paper discharge stack section 30 on the apparatus main body A. A discharge roller pair 31 is provided.
On the other hand, below the transfer paper carrier 18, a refeed unit 33 that refeeds the transfer paper that has been reversed by the reversing unit 29 along the extending direction between the pair of guide plates 32. Are arranged diagonally.
Below the re-feed unit 33, the paper feed cassettes 34 are provided in two upper and lower stages. In the paper feed cassette 34, different sizes of transfer paper such as paper and OHP film are stacked and stored. A sheet feeding unit 35 is provided for separating and feeding the transfer sheets one by one.
On the right side of the paper feed unit 35 in the figure, the transfer paper fed from the paper feed unit 35 and the transfer paper re-feeded through the re-feed unit 33 are guided to the registration roller pair 23 in the transfer paper transport path P. A paper feed path P2 is provided.
Further, a manual feed section is provided on the right side of the apparatus main body A in the figure, and a manual feed tray 36 is attached to the manual feed section so as to be opened and closed. The manual feed portion is provided with a paper feed portion 37 that separates and feeds the transfer sheets on the manual feed tray 36 one by one, and manually feeds the transfer paper fed from the paper feed portion 37 to the registration roller pair 23. A paper path P3 is provided.

Now, when recording an image on transfer paper using this color printer, for example, the paper feed unit 35 is selectively driven based on a signal from the host to transfer the transfer paper in one paper feed cassette 34. The sheets are separated and fed one by one, put into the paper feed path P2, and abutted against the registration roller pair 23 to stop.
Alternatively, the manual paper feed unit 37 is driven to separate and feed the transfer paper material on the manual tray 36 one by one, put into the manual paper feed path P3, and abut against the registration roller pair 23 to stop.
On the other hand, in each monochromatic image forming means 10Y, 10M, 10C, 10B, the individual image carriers 14Y, 14M, 14C, 14B are rotated, and yellow and magenta are respectively formed on the image carriers 14Y, 14M, 14C, 14B. , Cyan and black single color toner images are formed. At the same time, one of the support rollers 19 is rotationally driven by a drive motor (not shown), the other support rollers 19 are driven to rotate, and the transfer paper carrier 18 is rotated and conveyed.
At that time, the registration roller pair 23 is rotated in synchronization with the rotation of the image carriers 14Y, 14M, 14C, and 14B, the transfer material is put into the transfer material conveyance path P, and the monochromatic image forming means 10Y, 10M, 10C, 10B and the transfer material carrier 18, and the transfer paper carrier 18 is rotated and conveyed to convey the transfer paper.
At the same time, the monochrome toner images on the individual image carriers 14Y, 14M, 14C, and 14B are transferred by the transfer brushes 21Y, 21M, 21C, and 21B, and the combined full-color images are recorded on the transfer paper.

The transfer paper after the image transfer is sent to the fixing unit 24 to fix the transferred image, and is then discharged by the discharge roller pair 27. When discharging in the face-down state, the sheet is switched by a switching claw (not shown) and guided to the reverse discharge path P1, discharged by the discharge roller pair 31, and stacked on the discharge stack unit 30 in page order.
When discharging in the face-up state, it is switched with a switching claw (not shown), led to the reversing unit 29, and discharged straight as it is.
Six CISs (contact image sensors) 106 are arranged in a direction perpendicular to the transfer sheet conveyance direction as photosensors for detecting image information on the transfer sheet after fixing at a position immediately after passing through the fixing unit 24.
The image on the transfer sheet may be detected by a single line-shaped sensor corresponding to the maximum transfer sheet size, and the image information may be divided into a plurality of areas. The image area on the transfer paper is calculated based on the amount of light received by the photosensor, and the image area ratio of each region is calculated together with information on the running area of the transfer paper. This will be described in detail later.
Similarly, when recording on the back side of a transfer material on which single-sided recording has been performed, switching is performed with a switching claw (not shown) and led to the reversing unit 29, reversed by the reversing unit 29, and then led to the refeed unit 33. Then, the sheet is again put in the paper feed path P2 and abutted against the registration roller pair 23 and stopped.
The sheet is again put in the transfer material conveyance path P, sent between the monochrome image forming means 10Y, 10M, 10C, and 10B and the transfer paper carrier 18 to record a composite full color image on the back surface, and then fixed by the fixing unit 24. To do. Thereafter, for example, the paper is discharged by the discharge roller pair 31 through the reverse paper discharge path P <b> 1 and stacked on the paper discharge stack unit 30.

FIG. 2 is a schematic sectional view showing an image carrier unit used in the color printer of FIG. Next, the individual monochromatic image forming means 10Y, 10M, 10C, and 10B will be described in detail below. In each image carrier unit 12 (12Y, 12M, 12C, 12B) of each single color image forming means 10Y, 10M, 10C, 10B, as shown in FIG. 2, a drum-like image carrier 14 (14Y described later) will be described in detail. , 14M, 14C, 14B), a charging device 40 and a cleaning device 41 are provided.
The charging device 40 arranges a roller-shaped charging member 42 in the vicinity of the image carrier 14, and charges the image carrier 14 by applying a charging bias between the charging member 42 and the image carrier 14. The charging member 42 is brought into contact with a cleaner 43 made of sponge or the like for cleaning the surface thereof. In the illustrated example, the charging member 42 has a roller shape, but may be a known non-contact charger.
The cleaning device 41 includes a fur brush 44 that is rotatable in contact with the image carrier 14 on its outer periphery, and a cleaning blade 45 made of polyurethane rubber, for example, with its tip pressed against the image carrier 14. In the figure, reference numeral 46 denotes a toner recovery screw.
The fur brush 44 is rotated in the opposite direction to the image carrier 14 to remove transfer residual toner remaining on the image carrier 14 after image transfer. Thereafter, the toner still remaining on the image carrier 14 is scraped off and removed by the cleaning blade 45. In the illustrated example, the toner removed by the fur brush 44 and the cleaning blade 45 is discharged from the monochrome image forming units 10Y, 10M, 10C, and 10B by the rotation of the toner collecting screw 46, and is provided in the apparatus main body A. It passes through a waste toner transport path that is not present and is transported to a waste toner bottle.
Each image carrier unit 12 is provided with a portion 47 serving as a main positioning reference and two portions 48 serving as a secondary positioning reference, which can be accurately positioned and attached to the apparatus main body A. I am doing so.

On the other hand, in each of the developing units 13Y, 13M, 13C, and 13B that are the developing devices of the individual monochromatic image forming units 10Y, 10M, 10C, and 10B, a one-component developer may be used. And a two-component developer comprising a non-magnetic toner. As the non-magnetic toner, yellow toner is used in the developing unit 13Y, magenta is used in the developing unit 13M, cyan is used in the developing unit 13C, and black toner is used in the developing unit 13B.
In each single color image forming means 10Y, 10M, 10C, 10B, as the image carrier 14 rotates in the clockwise direction in FIG. 2, a charging bias is applied by the charging device 40, and the surface of the image carrier 14 is applied. Charge uniformly. Next, writing is performed with scanning light from the writing unit 16 (FIG. 1), and an electrostatic latent image is formed on the surface of the image carrier 14. Then, the developing unit 13 (13Y, 13M, 13C, 13B) attaches toner and develops the electrostatic latent image to form a monochromatic toner image on the image carrier 14.
A yellow single color toner image is formed on the image carrier 14Y of the monochromatic image forming unit 10Y, a magenta single color toner image is formed on the image carrier 14M of the single color image forming unit 10M, and an image carrier 14C of the single color image forming unit 10C is formed on the image carrier 14C. A cyan single color toner image and a black single color toner image are formed on the image carrier 14B of the single color image forming unit 10B. Although not shown, each developing unit 13 is provided with a toner density detection sensor.
On the image carrier 14, a photo sensor 107 for detecting image information is arranged in a direction orthogonal to the conveyance direction, and an image information calculation unit to be described later reads out the image of each region from the image information read from the photo sensor 107. Information is calculated.
Six CISs 107 as photosensors are arranged in series in the direction orthogonal to the rotation direction of the image carrier 14 at a position downstream of the developing roller 13 a of the developing unit 13 of the image carrier 14. The toner developed on the image carrier 14 by the developing roller 13a is read by the photo sensor 107, and the image area is estimated from the light amount data, thereby calculating the image area ratio.

  FIG. 3 is a schematic view showing a photosensor arranged on the intermediate transfer member of the image forming apparatus. Referring to FIG. 3, the image formed on the four-color image carrier 14 is temporarily transferred onto the intermediate transfer member 109 and further transferred onto the transfer paper by the secondary transfer roller 110. A charging roller, a developing unit, and a cleaning unit are arranged around the image carrier 14 as in FIG. Further, a photo sensor 108 provided near the right end of the intermediate transfer member 109 is shown. The photo sensor 108 will be described in detail later.

FIG. 4 is a schematic configuration diagram showing a writing unit used in the color printer of FIG. Next, the writing unit 16 will be described in detail. As shown in FIG. 4, the writing unit 16 is provided with two six-sided rotary polygon mirrors 51 and 52 that can be rotated by a polygon motor 50. Then, light emitted from a laser diode (not shown) is reflected by being divided into scanning light for yellow, magenta, cyan, and black by the rotation of the rotary polygon mirrors 51 and 52.
The yellow scanning light passes through the fθ lens 53, is reflected by the mirror 54, passes through the long WTL 55, is reflected by the mirrors 56, 57, and irradiates the image carrier 14Y of the image carrier unit 12Y.
The magenta scanning light is reflected by the mirror 58 through the fθ lens 53, is reflected by the mirrors 60 and 61 through the long WTL 59, and irradiates the image carrier 14M of the image carrier unit 12M.
The scanning light for cyan is reflected by the mirror 63 through the fθ lens 62, is reflected by the mirrors 65 and 66 after passing through the long WTL 64, and irradiates the image carrier 14C of the image carrier unit 12C.
The scanning light for black is reflected by the mirror 67 through the fθ lens 62, is reflected by the mirrors 69 and 70 through the long WTL 68, and irradiates the image carrier 14B of the image carrier unit 12B.

FIG. 5 is a schematic diagram showing control blocks in the color printer of FIG. As can be seen from FIG. 5, a main control board 80 is provided in the laser printer. The main control board 80 is supplied with power from a power supply unit 81 and is connected to a personal computer (PC) 83 via a controller board 82 via a network or the like. An operation / display panel 84 is also connected to the controller board 82.
For example, the main control board 80 is connected to the writing control unit 85 to control the writing unit 16 (FIG. 4), drives the polygon motor 50 of the writing unit 16, and the image carrier 14 and the developing unit 13 (FIG. 1). The image bearing member / development drive motor 87 for driving the motor is driven, the fixing device 24 (FIG. 1) and the fixing / paper feed drive motor 88 for driving the paper feed system roller are driven, and various clutches such as the development clutch 94 Turn on and off.
On the other hand, various detection sensors are operated to control the high voltage power supply unit 89 to apply various bias voltages, to control the toner replenishment motor 91 based on the output signal of the toner density sensor of the developing unit 13, and the thermistor of the fixing device 24. Based on the output signal 92, the fixing heater 93 is turned on and off.
Further, when an image is formed on transfer paper using this laser printer, the image carrier 14 is rotated by driving the image carrier / development drive motor 87 based on a signal from the personal computer 83 as a host. As the image carrier 14 rotates, the surface thereof is first uniformly charged by the charging device (charging roller) 40 by applying a charging bias by the high-voltage power supply unit 89.
Next, the writing control unit 85 is operated to perform writing by irradiating the writing light L with the writing device 16 to form an electrostatic latent image on the image carrier 14. Subsequently, by simultaneously driving the development unit 13 based on the image carrier / development drive motor 87, the development roller provided in the development unit 13 is driven, and the development bias is applied by the high-voltage power supply unit 89, thereby causing the image carrier. A toner is attached to the image carrier 14 to visualize the electrostatic latent image on the image carrier 14 to form a toner image on the image carrier 14.

FIG. 6 is a partial sectional view showing the structure of the image carrier used in the color printer of FIG. FIG. 7 is a partial cross-sectional view showing the configuration of another image carrier. Next, the image carrier 14 used in each image carrier unit 12 will be described in detail below.
For example, as shown in FIG. 6 or FIG. 7, the image carrier 14 is configured by forming a photosensitive layer 73 on a conductive support 72 and providing a protective layer 74 on the photosensitive layer 73. The photosensitive layer 73 is made of the charge generation layer 75 and the charge transport layer 76, but the charge transport layer 76 may be provided on the charge generation layer 75 as shown in FIG. 6, or conversely as shown in FIG. In addition, a charge generation layer 75 may be provided on the charge transport layer 76.
The conductive support 72 has a volume resistance of 10 ¹⁰ Ωcm or less, for example, a metal such as aluminum, nickel, chromium, nichrome, copper, silver, gold, platinum, or a metal oxide such as tin oxide or indium oxide. Surface of the product by cutting, super-finishing, polishing, etc. after forming a plate of aluminum or aluminum alloy, nickel, stainless steel, etc. It consists of a treated tube.

The charge generation layer 75 is a layer mainly composed of a charge generation material. As the charge generation material, an inorganic or organic material is used, and typical examples include monoazo pigments, disazo pigments, trisazo pigments, perylene pigments, perinone pigments, quinacridone pigments, quinone condensed polycyclic compounds, squaric. Examples include acid dyes, phthalocyanine pigments, naphthalocyanine pigments, azulenium salt dyes, selenium, selenium-tellurium alloys, selenium-arsenic alloys, and amorphous silicon. These charge generation materials may be used alone or in combination of two or more.
The charge generation layer 75 is obtained by dispersing a charge generation material together with a binder resin, using a solvent such as tetrahydrofuran, cyclohexanone, dioxane, 2-butanone, dichloroethane, or the like by a ball mill, an attritor, a sand mill, or the like, and applying a dispersion. Can be formed. Application is performed by dip coating, spray coating, bead coating, or the like.
The binder resin used as appropriate is polyamide resin, polyurethane resin, polyester resin, epoxy resin, polyketone resin, polycarbonate resin, silicon resin, acrylic resin, polyvinyl butyral resin, polyvinyl formal resin, polyvinyl ketone resin, polystyrene resin, polyacrylic resin. And polyamide resin. The amount of the binder resin is suitably 0 to 2 parts with respect to 1 part of the charge generating material on a weight basis. The charge generation layer 75 can also be formed using a known vacuum thin film manufacturing method. The film thickness of the charge generation layer 75 is usually 0.01 to 5 μm, preferably 0.1 to 2 μm.
The charge transport layer 76 can be formed by dissolving or dispersing a charge transport material and a binder resin in an appropriate solvent, and applying and drying the solution. Moreover, a plasticizer, a leveling agent, etc. can also be added as needed.

Among charge transport materials, low molecular charge transport materials include electron transport materials and hole transport materials. Examples of the electron transport material include chloroanil, bromanyl, tetracyanoethylene, tetracyanoquinodimethane, 2,4,7-trinitro-9-fluorenone, 2,4,5,7-tetranitro-9-fluorenone, 2, 4,5,7-tetranitroxanthone, 2,4,8-trinitrothioxanthone, 2,6,8-trinitro-4H-indeno [1,2-b] thiophene-4-one, 1,3,7-tri Examples thereof include electron accepting substances such as nitrodibenzothiophene-5,5-dioxide. These electron transport materials may be used alone or as a mixture of two or more.
Examples of hole transport materials include oxazole derivatives, oxadiazole derivatives, imidazole derivatives, triphenylamine derivatives, 9- (p-diethylaminostyrylanthracene), 1,1-bis- (4-dibenzylaminophenyl) propane. , Styrylanthracene, styrylpyrazoline, phenylhydrazones, α-phenylstilbene derivatives, thiazole derivatives, triazole derivatives, phenazine derivatives, acridine derivatives, benzofuran derivatives, benzimidazole derivatives, thiophene derivatives, and the like. These hole transport materials may be used alone or as a mixture of two or more.
When a polymer charge transport material is used as the charge transport material, the charge transport layer 76 may be formed by dissolving or dispersing in a suitable solvent, coating and drying the solution. The polymer charge transport material may be any material that has the charge transporting substituent in the main chain or side chain in the low molecular charge transport material. Further, if necessary, an appropriate amount of a binder resin, a low molecular charge transport material, a plasticizer, a leveling agent, a lubricant and the like can be added to the polymer charge transport material.
Examples of the binder resin used for the charge transport layer 76 together with the charge transport material include polystyrene resin, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester resin, and polyvinyl chloride resin. , Vinyl chloride-vinyl acetate copolymer, polyvinyl acetate resin, polyvinylidene chloride resin, polyarylate resin, phenoxy resin, polycarbonate resin, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral resin, polyvinyl formal resin, polyvinyl toluene resin, acrylic Examples thereof include thermoplastic or thermosetting resins such as resin, silicon resin, epoxy resin, melamine resin, urethane resin, phenol resin, and alkyd resin.

Examples of the solvent include tetrahydrofuran, dioxane, toluene, 2-butanone, monochlorobenzene, dichloroethane, methylene chloride and the like. The thickness of the charge transport layer 76 may be appropriately selected in the range of 5 to 30 μm according to desired image carrier characteristics.
As the plasticizer added to the charge transport layer 76 as desired, general-purpose plasticizers such as dibutyl phthalate and dioctyl phthalate can be used, and the amount used is 0 to 30 based on the weight of the binder resin. % Is appropriate.
The leveling agent added to the charge transport layer 76 as desired includes silicone oils such as dimethyl silicone oil and methylphenyl silicone oil, and polymers or oligomers having a perfluoroalkyl group in the side chain. About 0 to 1% is appropriate for the binder resin on a weight basis.
The amount of the charge transport material contained in the photosensitive layer 73 is preferably 40% by weight or more of the charge transport layer 76. If it is less than 40% by weight, a sufficient light decay time in the high-speed electrophotographic process cannot be obtained in pulsed light exposure in laser writing on the image carrier, which is not preferable.
The charge transport layer mobility in the image carrier 14 is 3 × 10 ⁻⁵ cm ² / V under the condition of the charge transport layer electric field strength in the range of 2.5 × 10 ^{5 to} 5.5 × 10 ⁵ V / cm. It is preferably s or more, and more preferably 7 × 10 ⁻⁵ cm ² / V · s or more. This mobility can be adjusted as appropriate to achieve this under each use condition. This mobility may be obtained by a conventionally known TOF method.
An undercoat layer can be formed on the image carrier 14 between the conductive support 72 and the photosensitive layer 73. In general, the undercoat layer is mainly composed of a resin. However, considering that the photosensitive layer is coated with a solvent on the resin, it is desirable that the resin be a resin having high solubility in general organic solvents. .
Examples of such resins include polyvinyl alcohol resins, caseins, water-soluble resins such as sodium polyacrylate, alcohol-soluble resins such as copolymer nylon and methoxymethylated nylon, polyurethane resins, melamine resins, alkyd-melamine resins, and epoxy resins. And a curable resin that forms a three-dimensional network structure.

Further, fine powder of metal oxide such as titanium oxide, silica, alumina, zirconium oxide, tin oxide, and indium oxide may be added to the undercoat layer in order to prevent moire and reduce residual potential.
This undercoat layer can be formed by using an appropriate solvent and coating method in the same manner as the photosensitive layer 73 described above. Furthermore, it is also useful to use a metal oxide layer formed by, for example, a sol-gel method using a silane coupling agent, a titanium coupling agent, a chromium coupling agent or the like as the undercoat layer.
In addition, the undercoat layer is formed by anodizing Al ₂ O ₃ , organic matter such as polyparaxylylene (parylene), inorganic matter such as SiO, SnO ₂ , TiO ₂ , ITO, CeO ₂ It is also effective to form the film by a vacuum thin film manufacturing method. The thickness of the undercoat layer is suitably from 0 to 5 μm.
On the image carrier 14, a protective layer 74 containing a filler is formed on the photosensitive layer 73 as a surface layer for the purpose of protecting the photosensitive layer 73 and improving durability. Materials used for the protective layer 74 include ABS resin, ACS resin, olefin-vinyl monomer copolymer, chlorinated polyether resin, allyl resin, phenol resin, polyacetal resin, polyamide resin, polyamideimide resin, polyacrylate resin. And resins such as polyallylsulfone resin, polybutylene resin, polybutylene terephthalate resin, and polycarbonate resin.

Moreover, as a material used for the protective layer 74, polyether sulfone resin, polyether resin, polyethylene terephthalate resin, polyimide resin, acrylic resin, polymethylpentene resin, polypropylene resin, polyphenylene oxide resin, polysulfone resin, AS resin, AB resin , BS resin, polyurethane resin, polyvinyl chloride resin, polyvinylidene chloride resin, epoxy resin and the like. A filler is added to the protective layer 74 for the purpose of improving wear resistance.
Examples of the filler include fluorine resins such as polytetrafluoroethylene, silicon resins, and fillers in which inorganic materials such as titanium oxide, tin oxide, and potassium titanate are dispersed in these resins.
The amount of filler added to the protective layer 74 is usually 10 to 40%, preferably 20 to 30% on a weight basis. If the amount of the filler is less than 10%, the wear is large and the durability is inferior, and if it exceeds 40%, the increase in the light potential at the time of exposure becomes remarkable and the sensitivity reduction cannot be ignored.
Furthermore, a dispersion aid can be added to the protective layer 74 in order to improve the dispersibility of the filler. As the added dispersion aid, those used in paints and the like can be used as appropriate, and the amount thereof is usually 0.5 to 4%, preferably 1 to 2% based on the amount of filler contained on a weight basis. is there.
It is also effective to add the above-described charge transport material to the protective layer 74, and an antioxidant can be added as necessary. The antioxidant will be described later.

As a method for forming the protective layer 74, a normal coating method such as a spray method is employed. The thickness of the protective layer 74 is 0.5 to 10 μm, preferably about 4 to 6 μm. It is important for the wear resistance and image characteristics that the form of the filler in the protective layer 74 be constant. That is, the presence of the protective layer 74 does not impair the sensitivity and electrostatic stability of the photosensitive layer 73, and does not impair the fineness of exposure. It can contribute.
In order to satisfy this requirement, it is necessary that the filler content in an arbitrary cross section of the protective layer 74 is 3 to 5% as an area occupation ratio in the plane. Further, the filler contained in the protective layer 74 has a peak at 0.2 to 0.3 μm in the particle size distribution including secondary particles, and the filler has a particle size of 0.3 μm or more in an arbitrary cross section of the protective layer 74. It is necessary that the occupied area by is 10 to 30% of the occupied area of all fillers in the plane. As a result of the study by the present inventors, when it was not in the above range, it was confirmed that the residual potential increased, the sensitivity decreased, the resolution decreased, the wear resistance decreased, and abnormal image generation due to filming occurred.
The control of the form of the filler in the protective layer 74 is possible by the particle size and distribution of the filler material used, the coating liquid formulation, and the coating apparatus, and the use of a dispersion aid is effective.
It is also possible to form another intermediate layer between the photosensitive layer 73 and the protective layer 74. In the intermediate layer, a binder resin is generally used as a main component. Examples of the binder resin include polyamide resin, alcohol-soluble nylon, water-soluble polyvinyl butyral resin, polyvinyl butyral resin, and polyvinyl alcohol resin. As a method for forming the intermediate layer, the above-described normal coating method is employed. The thickness of the intermediate layer is suitably about 0.05 to 2 μm.
In order to improve environmental resistance, antioxidants, plasticizers, lubricants, UV absorbers, low-molecular charge transporting substances and leveling agents are added to each layer, especially for the purpose of preventing a decrease in sensitivity and an increase in residual potential. can do.

Examples of the antioxidant that can be added to each layer include 2,6-di-t-butyl-p-cresol, butylated hydroxyanisole, 2,6-di-t-butyl-4-ethylphenol, and n-octadecyl- 3- (4-hydroxy-3,5-di-tert-butylphenol), 2,2-methylene-bis- (4-methyl-6-tert-butylphenol), 2,2-methylene-bis- (4-ethyl) -6-tert-butylphenol), 4,4-thiobis- (3-methyl-6-tert-butylphenol), 4,4-butylidenebis- (3-methyl-6-tert-butylphenol), 1,1,3- Tris- (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl Benzene, and the like.
Examples of the antioxidant that can be added to each layer include tetrakis- [methylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] methane, bis [3,3-bis (4 -Hydroxy-3-t-butylphenyl) butyric acid] phenol compounds such as glycol ester, tocopherols, N-phenyl-N-isopropyl-p-phenylenediamine, N, N-di-sec-butyl- p-phenylenediamine, N-phenyl-N-sec-butyl-p-phenylenediamine, N, N-di-isopropyl-p-phenylenediamine, N, N-dimethyl-N, N-di-t-butyl-p -Paraphenylenediamines, such as phenylenediamine, etc. are mentioned.
Furthermore, as an antioxidant which can be added to each layer, for example, 2,5-di-t-octyl hydroquinone, 2,6-didodecyl hydroquinone, 2-dodecyl hydroquinone, 2-dodecyl-5-chlorohydroquinone, 2-t -Hydroquinones such as octyl-5-methylhydroquinone and 2- (2-octadecenyl) -5-methylhydroquinone, dilauryl-3,3-thiodipropionate, distearyl-3,3-thiodipropionate, ditetradecyl- Organic sulfur compounds such as 3,3-thiodipropionate, triphenylphosphine, tri (nonylphenyl) phosphine, tri (dinonylphenyl) phosphine, tricresylphosphine, tri (2,4-dibutylphenoxy) phosphine, etc. And organic phosphorus compounds.

Examples of plasticizers that can be added to each layer include triphenyl phosphate, tricresyl phosphate, trioctyl phosphate, octyl diphenyl phosphate, trichloroethyl phosphate, cresyl diphenyl phosphate, tributyl phosphate, tri-2-ethylhexyl phosphate , Phosphate ester plasticizers such as triphenyl phosphate, dimethyl phthalate, diethyl phthalate, diisobutyl phthalate, dibutyl phthalate, diheptyl phthalate, di-2-ethylhexyl phthalate, diisooctyl phthalate, di-phthalate n-octyl, dinonyl phthalate, diisononyl phthalate, diisodecyl phthalate, diundecyl phthalate, ditridecyl phthalate, dicyclohexyl phthalate, butyl benzyl phthalate, butyl lauryl phthalate, methyl oleyl phthalate, octyl phthalate Decyl, dibutyl fumarate, phthalic acid ester plasticizers such as dioctyl fumarate.
Examples of the plasticizer that can be added to each layer include aromatic carboxylic acid ester plasticizers such as trioctyl trimellitic acid, tri-n-octyl trimellitic acid, and octyl oxybenzoate, dibutyl adipate, and di-n adipic acid. -Hexyl, di-2-ethylhexyl adipate, di-n-octyl adipate, -n-octyl-n-decyl adipate, diisodecyl adipate, dicapryl adipate, di-2-ethylhexyl azelate, dimethyl sebacate, Diethyl sebacate, dibutyl sebacate, di-n-octyl sebacate, di-2-ethylhexyl sebacate, di-2-ethoxyethyl sebacate, dioctyl succinate, diisodecyl succinate, dioctyl tetrahydrophthalate, dihydrotetrahydrophthalate -N-octyl, etc. Aliphatic dibasic acid ester plasticizers.
Furthermore, as a plasticizer that can be added to each layer, for example, butyl oleate, glycerin monooleate, methyl acetylricinoleate, pentaerythritol ester, dipentaerythritol hexaester, triacetin, tributyrin, etc. Oxyacid ester plasticizers such as methyl ricinoleate, butyl acetyl ricinoleate, butyl phthalyl butyl glycolate, tributyl acetyl citrate, epoxidized soybean oil, epoxidized linseed oil, butyl epoxy stearate, decyl epoxy stearate, epoxy Epoxy plasticizers such as octyl stearate, epoxy benzyl stearate, dioctyl epoxy hexahydrophthalate, didecyl epoxy hexahydrophthalate, diethylene glycol Examples include dihydric alcohol ester plasticizers such as rudibenzoate and triethylene glycol di-2-ethylbutyrate, and chlorine-containing plasticizers such as chlorinated paraffin, chlorinated diphenyl, chlorinated fatty acid methyl, and methoxychlorinated fatty acid methyl. .

Furthermore, examples of the plasticizer that can be added to each layer include polyester plasticizers such as polypropylene adipate, polypropylene sebacate, polyester, and acetylated polyester, p-toluenesulfonamide, o-toluenesulfonamide, and p-toluenesulfonethylamide. Sulfonic acid derivative plasticizers such as o-toluenesulfone ethylamide, toluenesulfone-N-ethylamide, p-toluenesulfone-N-cyclohexylamide, triethyl citrate, triethyl acetylcitrate, tributyl citrate, tributyl acetylcitrate Citric acid derivative plasticizers such as acetyltricitrate tri-2-ethylhexyl, acetylcitrate-n-octyldecyl, etc., terphenyl, partially hydrogenated terphenyl, camphor, 2-nitrate Diphenyl, dinonyl naphthalene, methyl abietate, and the like.
Examples of lubricants that can be added to each layer include hydrocarbon compounds such as liquid paraffin, paraffin wax, microwax, low-polymerized polyethylene, lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, and behenic acid. Fatty acid compounds, stearylamide, palmitylamide, oleinamide, fatty acid amide compounds such as methylenebisstearoamide, ethylenebisstearoamide, fatty acid lower alcohol esters, fatty acid polyhydric alcohol esters, fatty acid polyglycol esters, etc. Ester compounds, cetyl alcohol, stearyl alcohol, alcohol compounds such as ethylene glycol, polyethylene glycol, polyglycerol, lead stearate, cadmium stearate, barium stearate, Calcium stearate, zinc stearate, metal soaps such as magnesium stearate, carnauba wax, candelilla wax, beeswax, spermaceti, insect wax, natural waxes such as montan wax, and other silicon compounds, and fluorine compounds.

Examples of ultraviolet absorbers that can be added to each layer include 2-hydroxybenzophenone, 2,4-dihydroxybenzophenone, 2,2,4-trihydroxybenzophenone, 2,2,4,4-tetrahydroxybenzophenone, and 2,2-dihydroxy. Benzophenone UV absorbers such as 4-methoxybenzophenone, salsylate UV absorbers such as phenyl salsylate, 2,4 di-t-butylphenyl 3,5-di-t-butyl 4-hydroxybenzoate, (2-hydroxy Phenyl) benzotriazole, (2-hydroxy5-methylphenyl) benzotriazole, (2-hydroxy5-methylphenyl) benzotriazole, (2-hydroxy3-tertiarybutyl 5-methylphenyl) 5-chlorobenzotriazole, etc. Benzotria Lumpur-based ultraviolet absorbers.
Examples of the ultraviolet absorber that can be added to each layer include cyanoacrylate-based ultraviolet absorbers such as ethyl-2-cyano-3,3-diphenyl acrylate and methyl 2-carbomethoxy 3 (paramethoxy) acrylate, nickel (2, 2 Quencher (metal complex) UV absorbers such as thiobis (4-t-octyl) phenolate) normal butylamine, nickel dibutyldithiocarbamate, nickel dibutyldithiocarbamate, cobalt dicyclohexyldithiophosphate, bis (2,2,6,6) -Tetramethyl-4-piperidyl) sebacate, bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, 1- [2- [3- (3,5-di-t-butyl-4 -Hydroxyphenyl) propionyloxy] ethyl] -4- [ -(3,5-di-t-butyl-4-hydroxyphenyl) propionyloxy] -2,2,6,6-tetramethylpyridine, 8-benzyl-7,7,9,9-tetramethyl-3- HALS (hindered amine) UV absorbers such as octyl-1,3,8-triazaspiro [4,5] undecane-2,4-dione, 4-benzoyloxy-2,2,6,6-tetramethylpiperidine, etc. Can be mentioned.

As described above, the image carrier 14 is formed by forming the photosensitive layer 73 and the protective layer 74 on the conductive substrate, forming an undercoat layer and an intermediate layer as required, and adding a filler to the protective layer 74. Improves resistance to wear and improves durability. Further, the image carrier 14 has excellent durability and stability with respect to a high-speed electrophotographic process by making the presence form of the filler in the protective layer 74 constant as described above, and Excellent wear resistance.
Further, by supplying zinc stearate onto the protective layer 74, filming can be suppressed with good wear resistance. Further, in the electrophotographic process including the image carrier 14, non-image formation is possible. Occasionally, the toner adheres to the image carrier 14 and the toner collecting operation in the cleaning unit is repeated, which has an effect of suppressing the image flow while maintaining the wear resistance. In the illustrated example, the image carrier 14 is formed in a drum shape, but may be formed in a belt shape having a high surface hardness.

By the way, the toner used in the present invention is externally added with 0.05 to 0.2 wt% of a lubricant (for example, zinc stearate). In this way, the lubricant can be applied to the surface of the carrier 14. In the above-described color printer, when an image is formed, for example, a charging bias is applied by the charging device 40. At that time, discharge products such as ozone and nitrogen oxide are generated and adhere to the image carrier 14, The image quality of the toner image recorded on the transfer material is degraded.
It has also been found that the surface layer of the image bearing member 14, which is an organic photoreceptor, oxidizes due to discharge and wear proceeds. By forming a thin layer of lubricant on the image carrier 14, the surface energy of the image carrier 14 is reduced, filming is prevented, and deposits are difficult to attach. At the same time, the lubricant layer serves as a protective layer to prevent oxidation of the surface layer of the image carrier 14 due to electric discharge and reduce wear of the image carrier 14. By externally adding a lubricant to the toner, it is possible to reduce the size and cost by eliminating the need for a dedicated lubricant application device.
The toner includes a binder resin, a colorant, and a charge control agent as main components, and other additives are added as necessary. Specific examples of the binder resin include polystyrene, chloropolystyrene, poly-α-methylstyrene, styrene-chlorostyrene copolymer, styrene-propylene copolymer, styrene-butadiene copolymer, and styrene-vinyl chloride copolymer. Styrene-vinyl acetate copolymer, styrene-maleic acid copolymer, styrene-acrylic acid ester copolymer (styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer) Polymer, styrene-phenyl acrylate copolymer, etc.) can be used.

Specific examples of the binder resin include styrene-methacrylic acid ester copolymers (styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-methacrylic acid). Styrene-based resins (styrene or styrene-substituted monopolymers or copolymers) such as acid phenyl copolymers, styrene-α-chloroacrylic acid methyl copolymers, styrene-acrylonitrile-acrylic acid ester copolymers, etc. ), Vinyl chloride resin, rosin-modified maleic acid resin, phenyl resin, epoxy resin, polyester resin, low molecular weight polyethylene, low molecular weight polypropylene, ionomer resin, polyurethane resin, ketone resin, ethylene-ethyl acrylate copolymer, xylene resin, polyvinyl Butyral etc. It can be used.
As coloring materials (for example, yellow, magenta, cyan and black) used for the toner, those known for toner can be used. The amount of the coloring material is suitably 0.1 to 15 parts by weight, more preferably 0.15 to 9 parts by weight, with respect to 100 parts by weight of the binder resin.
Specific examples of the charge control agent include nigrosine dyes, chromium-containing complexes, quaternary ammonium salts, and the like, which are properly used depending on the polarity of the toner particles. The amount of the charge control agent is 0.1 to 10 parts by weight, more preferably 0.2 to 7 parts by weight with respect to 100 parts by weight of the binder resin.
In addition, it is advantageous to add a fluidity imparting agent to the obtained toner particles. As the fluidity-imparting agent, fine particles of metal oxides such as silica, alumina, magnesia, zirconia, ferrite, magnetite and the like, and silane coupling agent, titanate coupling agent, zircoaluminate, quaternary ammonium salt, fatty acid, Surface-treated or coated with a treatment agent such as a fatty acid metal salt, a fluorine-based activator, a solvent, or a polymer is used.

Examples of the fluidity-imparting agent include fine particles of fatty acids such as stearic acid and zinc stearate or metal salts thereof, and those fine particles obtained by surface treatment with the above-mentioned treatment agent, such as polystyrene, polymethyl methacrylate, and polyvinylidene fluoride. Polymer fine particles and those obtained by surface treatment or coating of the fine particles with the above-mentioned treatment agent are used. These fluidity imparting agents have a particle size in the range of 0.01 to 3 μm.
The addition amount of these fluidity imparting agents is preferably in the range of 0.1 to 7.0 parts by weight, particularly 0.2 to 5.0 parts by weight with respect to 100 parts by weight of the toner particles. The mixing method of the toner particles and the fluidity-imparting agent is carried out so that the powder is moved at high speed by an air flow or mechanical force in a fluid state, and does not substantially cause pulverization. Examples of the mixer include a high-speed flow type mixer such as a Henschel mixer and a UM mixer.
As a method for producing a toner for two-component developer, it can be produced by various known methods or a combination thereof. For example, in the kneading and pulverization method, a binder resin, a colorant such as carbon black, and the necessary additives are dry-mixed, heated and melt-kneaded with an extruder or two rolls, three rolls, etc., cooled and solidified, The toner is obtained by pulverization with a pulverizer such as a jet mill and classification with an airflow classifier. It is also possible to produce a toner directly from a monomer, a colorant, and an additive by suspension polymerization or non-aqueous dispersion polymerization.
The carrier core material is generally made of itself or having a coating layer on the core material. The core material of the resin-coated carrier that can be used in the present invention is ferrite or magnetite. The particle size of the core material is 20 to 65 μm, preferably about 30 to 60 μm.
Fluorine-containing monomers used for carrier coating layer formation include vinylidene fluoride, tetrafluoroethylene, hexafluoropropylene, perfluoroalkyl vinyl ether, vinyl ether substituted with fluorine atoms, and vinyl ketone substituted with fluorine atoms. There is.

As vinyl ketone polymers, vinylidene fluoride-tetrafluoroethylene copolymer, vinylidene fluoride-hexafluoropropylene copolymer, perfluoroalkyl vinyl ether-vinylidene fluoride-tetrafluoroethylene copolymer, vinylidene fluoride polymer , Tetrafluoroethylene copolymer, polymer containing vinyl ether substituted with fluorine atom, polymer containing vinyl ketone substituted with fluorine atom, fluorinated alkyl acrylate polymer, or fluorinated alkyl methacrylate polymer There is a coalescence.
The components copolymerized with the fluorine-containing monomer include styrene, methylstyrene, dimethylstyrene, trimethylstyrene, acrylic acid, methacrylic acid, methyl acrylate, methyl methacrylate, butyl acrylate, butyl methacrylate, and benzyl acrylate. Benzyl methacrylate, acrylic acid amide, methacrylic acid amide, cyclohexyl acrylate, cyclohexyl methacrylate, hydroxyethyl acrylate, glycidyl acrylate, glycidyl methacrylate, vinyl acetate, ethylene, propylene, and the like. As a method for forming the coating layer, a resin may be applied to the surface of the carrier core particles by a spraying method, a dipping method, or the like, as in the past.
In the illustrated example described above, the case where the present invention is applied to a color printer has been described. However, the present invention can be similarly applied to a copying machine, a facsimile, or other image forming apparatuses. Further, the present invention can be applied not only to full color but also to a two-color or monochrome image forming apparatus.

FIG. 8 is a block diagram showing control of lubricant supply. In this lubricant supply control block diagram, the pixel number counting means 100 counts the number of pixels to be written, and the image area calculating means 101 calculates the image area based on the output of the pixel number counting means 100.
Since the image area of the image developed by the developing unit 13 (FIG. 1) and formed on the image carrier 14 (FIG. 1) has a one-to-one relationship with the light amount of the photosensor, the image area is estimated from the photosensor output. can do.
The image area of the image developed by the developing unit 13 and formed on the image carrier 14 can be calculated from the following equation.
[Image area] = [Count pixel count] × [1 pixel area]
Here, since the area of one pixel is determined in advance, the image area can be known by counting the number of pixels to be written by the pixel number counting means 100.
Then, according to the calculation result of the image area calculating unit 101, the lubricant supply executing unit 105 is operated, and the developing unit 13 attaches the developer separately from the development purpose in the image formation and supplies the lubricant to the image carrier 14. .
In FIG. 8, there is a counting unit 102 that counts the number of rotations or the rotation time of the image carrier 14, and the traveling area calculation unit 103 calculates the traveling area of the image carrier 14 based on the output of the counting unit 102.
The traveling area of the image carrier 14 can be calculated from the following equation.
[Traveling area] = [traveling distance] x [imaging width]

Here, since the image forming width is determined in advance, the traveling area can be known by obtaining the traveling distance.
The travel distance can be calculated from the following equation.
[Travel distance] = [count rotation speed of image carrier] × [peripheral length of image carrier] or [travel distance]
Here, since the circumference of the image carrier 14 is determined in advance, the traveling distance can be known by counting the number of rotations of the image carrier 14 by the counting means 102. Alternatively, the travel distance may be calculated by counting the rotation time based on the linear velocity of the image carrier 14.
The outputs of the image area calculating unit 101 and the traveling area calculating unit 103 are input to the image area rate calculating unit 104, and an image area ratio that is a ratio of the image area to the traveling area of the image carrier 14 is calculated from the following equation. .
[Image area ratio] = [Image area] / [Running area]
Judging from the calculated image area ratio, the lubricant supply execution means 105 is operated, and the developing unit 13 attaches the developer separately from the development purpose in image formation and supplies the lubricant to the image carrier 14.
By using the image area ratio obtained by dividing the number of pixels by the traveling area as the image information, the toner is more accurately supplied, the surface state of the image carrier 14 and the toner charge amount on the developing unit 13 are averaged, and the toner is wasted. Therefore, it is possible to accurately determine whether or not to supply the toner without consuming it, and to provide an image forming apparatus with a stable image.

FIG. 9 is a flowchart showing an example of lubricant supply. Referring to FIG. 5, FIG. 8, and FIG. 9, when image data is received from controller 83 connected via network or the like, CPU of main control board 80 is stored in NVRAM (nonvolatile memory). The current lubricant supply conditions (whether or not to execute the exposure pattern) are read (S1).
Next, the pixel number counting means 100 starts counting the number of pixels P1 to Pn in the N-divided area in the direction orthogonal to the conveyance (rotation) direction of the image carrier 14, and the rotation number of the image carrier 14 or The rotation time counting means 102 starts counting the number of rotations or rotation time of the image carrier 14 (S2).
Subsequently, the image carrier 14 is rotated, and charging, writing, development, transfer, cleaning, static elimination, etc. are repeated to form a toner image on the image carrier 14, and the toner image is transferred and recorded on the transfer paper. (S3).

After finishing the image formation on the last transfer paper of one job (from the start of rotation of the image carrier 14 to the stop thereof), it is determined whether or not to supply the lubricant (S4), In the case of execution, the lubricant supply is executed by the lubricant supply execution means 105 (S5).
The rotation of the image carrier 14 is stopped (S6). That is, the lubricant supply execution means 105 finishes the developing operation for the latent image corresponding to the last transfer paper of one job, and then attaches the developer separately from the development purpose in the image formation by the developing unit 13. Lubricant is supplied to the carrier. If it is not necessary to supply the lubricant, the process proceeds from step S4 to step S6, and the rotation of the image carrier 14 is stopped.
After the rotation of the image carrier 14 is stopped, the number of pixels P1 to Pn written in each region is counted by the pixel number counting unit 100 described above, and the image area ratio calculating unit 104 based on the output outputs the image area of each region. S1 to Sn are calculated. On the other hand, the counting means 102 counts the number of rotations of the image carrier 14, and the traveling area calculation means 103 calculates the traveling area of the image carrier 14 based on the output.
Then, the image area ratio calculating unit 104 calculates the image area ratios H1 to Hn of the respective areas from the image areas S1 to Sn calculated by the image area ratio calculating unit 104 and the traveling area Sa calculated by the traveling area calculating unit 103. . When there is a region lower than the predetermined reference image area ratio Hs, the lubricant is supplied only in that region.
Also, new lubricant supply conditions are determined based on the calculation result. Then, the lubricant supply condition is updated by storing it in NVRAM (S7), and the count values of the pixel number counting means 100 and the counting means 102 are cleared.

FIG. 10 is a flowchart showing an example of determination of the lubricant supply condition in step S7 of FIG. Referring to FIGS. 5, 8, and 10, first, image area ratios H1 to Hn of regions S1 to Sn divided into N in a direction orthogonal to the conveying direction of image carrier 14 (FIG. 1) are calculated (S8). ).
Next, it is checked whether or not the minimum value Hmin of these H1 to Hn is smaller than a predetermined reference image area ratio Hs (S9). If Hmin> Hs is not satisfied, execution of lubricant supply by exposure and development is determined for the region Sx where Hx <Hs among S1 to Sn (S10).
After the next job is completed, the lubricant is supplied based on the updated new lubricant supply condition. In this way, by controlling the lubricant supply condition based on the previous job count result, the lubricant supply condition is determined by counting the number of rotations of the image carrier 14 and the number of writing pixels in real time during the job. Control can be performed, and the load on the CPU can be greatly reduced to simplify the program.
By the way, the lubricant supplied to the image carrier 14 is stretched using the cleaning blade 45 (FIG. 2) of the cleaning device, and the lubricant is uniformly applied to the surface of the image carrier 14. As a result, it is possible to provide an image forming apparatus capable of effectively reducing the surface free energy of the image carrier by uniformly applying a lubricant to the surface of the image carrier with minimal toner consumption.
Therefore, in an image forming apparatus using a contact type transfer device (transfer paper carrier) 18, the transfer device 18 is separated from the image carrier 14 during the lubricant supply operation, or during the transfer operation. It is preferable to increase the supply efficiency of the lubricant by applying a reverse polarity bias voltage to prevent the toner from adhering to the transfer device 18.
Assuming that the image area ratio is the same as the transfer paper area, the toner consumption will be different if the transfer paper size is different even if the image area ratio is the same. However, by obtaining the image area ratio with respect to the traveling area of the image carrier 14 as described above, it is possible to form images on transfer papers of various sizes, or to form images one after another in large quantities. In various cases, it is possible to more accurately detect the toner consumption amount and predict the influence on the image carrier wear.

FIG. 11 is a flowchart showing another example of lubricant supply. 8 and 11, when image data is received, first, an image forming process such as charging, writing, developing, transferring, and cleaning is started (S11), and counting of the number of pixels to be written (image area) is started. At the same time, counting of the number of rotations or rotation time of the image carrier 14 (FIG. 1) is started (S12).
Next, it is determined whether or not a predetermined time has elapsed since the start of the image forming operation (S13). A lubricant supply operation is executed (S15). Then, the count value is cleared (S16), and each count is restarted. When the image forming operation is finished (S17), the rotation of the image carrier 14 is stopped (S18), and the count value is cleared (S19).
In this way, the lubricant supply execution means 105 completes the image forming operation on the previous transfer paper in one job and then starts the image on the developing unit 13 before starting the image forming operation on the next transfer paper. Apart from the development purpose in formation, a developer may be attached to supply the lubricant to the image carrier 14.

<Example 1>
As shown in FIG. 6, an undercoat layer, a charge generation layer 75, a charge transport layer 76, and a protective layer 74 are applied in that order on an aluminum substrate (conductive support 72) having a diameter of 30 mm, and then dried. Then, the image carrier 14 including an undercoat layer of 3.5 μm, a charge generation layer 75 of 0.15 μm, a charge transport layer 76 of 20 μm, and a protective layer 74 of 5 μm was produced. At this time, coating of the protective layer 74 was performed by a spray method, and other than that was performed by a dip coating method. The protective layer 74 was added with 25 wt% of alumina having an average particle size of 0.3 μm.
The developing unit 13 used a two-component developing system, and 0.15 wt% zinc stearate was added to the toner. The writing light L was laser light having a wavelength of 655 nm, and charging was performed by applying AC (2 kHz, 1.8 kVpp) + DC (−750 V) to the charging roller. The process speed is 125 mm / s. In such an electrophotographic process, durability was evaluated using three types of charts.
Chart 1 is a chart with an average image area ratio of 5% in which characters are arranged on average.
Chart 2 is a chart having an average image area ratio of 1.5% in which characters are arranged almost averagely.
Chart 3. A chart in which image data is arranged in the left half and characters are arranged in the right half. The left half has an average image area ratio of 20% and the right half has an average image area ratio of 1.5%. The average image area ratio is about 11%.
If there are areas where the average image area ratios H1 to H6 are 2% or less in each area divided into six areas in the direction perpendicular to the rotation direction of the image carrier (photosensitive body) 14, only that area is included. It was set to perform exposure development and to perform a lubricant supply operation.
Specifically, when there is a region where the average image area ratio in the region is 2% or less every time one job is finished, a horizontal line of 4 dots of 600 dpi is provided for that region of the image carrier 14. Ten lines were exposed and developed at intervals of 32 dots, and toner and lubricant were supplied onto the image carrier 14.

Under these conditions, 5 sheets per job were evaluated, and a total of 60,000 sheets were evaluated. In the case of Chart 1 (average image area ratio 5%), the wear amount of the image carrier 14 was about 1.6 μm, and about 11,000 sheets of image could be formed per toner bottle. In the case of Chart 2 (average image area ratio 1.5%), the wear amount of the image carrier 14 was about 1.8 μm, and about 28,000 images could be formed per toner bottle.
In the case of chart 3 (the figure and characters are unevenly distributed, the average image area ratio of the entire chart is 11%), the wear amount of the image carrier 14 corresponding to the left side of the chart (average image area ratio of 20%) is 1.3 μm, the chart The amount of wear of the image carrier 14 corresponding to the right side (average image area ratio 1.5%) was 1.7 μm, and about 77,000 images could be formed per toner bottle. The image was good regardless of the image area ratio. One toner bottle contains 275 g of toner.
Table 1 summarizes the evaluation of each chart for Example 1 and Example 4.

<Comparative Example 1>
In Comparative Example 1, 60,000 sheets were evaluated in the same manner as in Example 1 except that the lubricant supply operation was not performed regardless of the image area ratio in Example 1. In the case of Chart 1 (average image area ratio 5%), the wear amount of the image carrier 14 was about 1.8 μm, and about 12,000 images could be formed per toner bottle.
In the case of Chart 2 (average image area ratio 1.5%), it was possible to form an image of about 30,000 or more per toner bottle, but the wear amount of the image carrier 14 was 4.6 μm, and the wear As a result, the protective layer 74 was partially lost. Also, vertical black streak-like stains were generated in the image.
In the case of chart 3 (the figure and characters are unevenly distributed, the average image area ratio of the entire chart is 11%), the wear amount of the image carrier 14 corresponding to the left side of the chart (average image area ratio of 20%) is 1.4 μm, the chart The wear amount of the portion of the image carrier 14 corresponding to the right side (average image area ratio 1.5%) is 4.2 μm, and the protective layer 74 is partially lost due to wear, and the image has vertical black stripes. It has occurred. About 88,000 images could be formed per toner bottle.

<Comparative example 2>
In Comparative Example 2, in the case of Example 1, when the average image area ratio of one chart is 2% or less, the lubricant supply operation is set to be performed on the entire surface. The sheet was evaluated.
In the case of Chart 1 (average image area ratio 5%), the wear amount of the image carrier was about 1.6 μm, and about 11,000 sheets could be formed per toner bottle, and the image was good. In the case of Chart 2 (average image area ratio 1.5%), the wear amount of the image carrier 14 was about 1.5 μm, the image was good, and about 280,000 images could be formed per toner bottle.
In the case of chart 3 (the figure and characters are unevenly distributed, the average image area ratio of the entire chart is 11%), the wear amount of the image carrier 14 is 1.3 μm at the portion corresponding to the right side of the chart (image area ratio of 20%), the left side of the chart The portion corresponding to (image area ratio 1.5%) was 4 μm, and vertical black stripes were generated on the image. About 88,000 images could be formed per toner bottle.

<Comparative Example 3>
In Comparative Example 3, when the image area ratios H1 to H6 of the region divided into six in Example 1 are 2% or less, the lubricant supply operation is set to be performed on the entire surface. In the same way, 60,000 sheets were evaluated.
In the case of Chart 1 (average image area ratio 5%), the wear amount of the image carrier was about 1.6 μm, and about 11,000 sheets could be formed per toner bottle, and the image was good. In the case of Chart 2 (average image area ratio 1.5%), the wear amount of the image carrier 14 was about 1.5 μm, the image was good, and about 270,000 images could be formed per toner bottle.
In the case of chart 3 (the figure and characters are unevenly distributed, the average image area ratio of the entire chart is 11%), the wear amount of the image carrier 14 is 1.3 μm at the portion corresponding to the right side of the chart (image area ratio of 20%), the left side of the chart The portion corresponding to (image area ratio 1.5%) was 1.7 μm, and no image abnormality was observed, but only about 5,000 images could be formed per toner bottle.
Table 2 summarizes evaluations regarding the respective charts for Comparative Examples 1 to 3.

<Example 2>
In Example 1, the condition for the lubricant supply operation was determined from the image area ratio of the previous image forming operation. In this case, since the lubricant supply condition is determined only from the image area rate of the immediately previous one image forming operation, once the image forming operation with a low image area is executed, the image forming operation before and after that is very Even in the case of an image forming operation with a high image area ratio, the lubricant supply operation is executed.
Therefore, the average of the image area ratio is calculated not only from the previous one image forming operation but also from a plurality of image forming operations, and the lubricant supply conditions are determined from the average image area ratio, thereby further minimizing toner consumption. It ’s better to stay on top.
For example, when obtaining the average image area ratio from the last five image forming operations, an area for storing the number of rotations or rotation time of the image carrier 14 and the count of the number of write pixels is secured on the NVRAM. The total traveling area and the total image area are obtained from the count values for the last five times.
[Total traveling area] = [Total of 5 traveling distances] x [Image width]
[Total image area] = [Total number of pixels counted five times] × [Area of one pixel]
The following average image area ratio is calculated from the total traveling area and the total image area thus obtained.
[Average image area ratio] = [Total image area] / [Total travel area]
The lubrication supply operation is the same as that in the first embodiment.

<Example 3>
In an image forming apparatus that is often used in a usage method in which one image forming operation is several to at most ten, it is effective to supply the lubricant for each job. However, in an image forming apparatus that is often used for large-scale printing in which the number of image forming operations at one time is at least several tens or more, the supply of lubricant before the image carrier 14 is stopped corresponds to the number of printed sheets. The frequency is low and sufficient effects cannot be obtained.
Therefore, in such an image forming apparatus, it is effective to temporarily interrupt the image forming operation and perform the lubricant supply operation during the image forming operation. Even when the lubricant supply operation is performed during the image forming operation, it is not necessary to stop the image carrier 14, and the toner is applied to the image carrier 14 between the transfer sheets with the paper feeding interval wider than usual while continuously rotating. What is necessary is just to adhere.
By controlling the exposure amount, the supply amount of the lubricant can be easily adjusted. As a control method, when the image forming operation continues even after a lapse of a predetermined time (for example, 100 seconds) from the start of the image forming operation, the image area ratio is determined. Stops the image forming operation and performs the lubricant supply operation. The calculation method of the image area ratio and the determination method of the supply condition of the lubricant are the same as those in the first and second embodiments.

<Example 4>
In Example 1, it was determined whether or not to supply the lubricant depending on whether or not the average image area ratio is 2% or less. Lubricant can also be supplied. As shown in Table 3, the toner consumption can be reduced by dividing the level according to the image area ratio in the region and finely setting the exposure pattern according to the level.
Table 3 shows that the supply of the lubricant is classified according to the image area ratio in the region.

As described above, according to the present invention, the exposure pattern is determined for each area according to the average image information of each area, and the surface state of the image carrier is accurately averaged with the minimum amount of toner supplied to each area. Thus, it is possible to provide an image forming apparatus capable of improving the durability of the image carrier by suppressing the occurrence of abnormal images and reducing the consumption of toner as much as possible.
Further, according to the present invention, the developer contains a lubricant, and the lubricant can be applied to the surface of the image carrier by exposure and development, and a document in which the size of the image area ratio is unevenly distributed. Even when output continuously, lubricant can be easily applied to each area of the image carrier, and the free energy on the surface of the image carrier is made uniform with minimal toner consumption, and uneven wear of the image carrier is achieved. In addition, it is possible to provide a stable image forming apparatus in which no abnormal image is generated due to foreign matter adhering to the surface of the photoreceptor.
Furthermore, according to the present invention, the cleaning device for removing the toner remaining on the image carrier with the cleaning blade is provided, and the lubricant supplied together with the toner to the image carrier is extended with the cleaning blade, thereby minimizing the toner consumption. It is possible to provide an image forming apparatus capable of effectively reducing the surface free energy of the image carrier by uniformly applying a lubricant to the surface of the image carrier.
In addition, according to the present invention, an organic photoreceptor is used as an image carrier, and a protective layer containing a filler is provided on the surface of the organic photoreceptor. An image forming apparatus capable of obtaining a stable image by further improving the effect of improving the durability of the image carrier by supplying a lubricant, using an image carrier having an improved image quality.
Further, other examples according to the present invention and other comparative examples will be described.

<Example 5>
As shown in FIG. 6, an undercoat layer, a charge generation layer 75, a charge transport layer 76, and a protective layer 74 are applied in that order on an aluminum substrate (conductive support 72) having a diameter of 30 mm, and then dried. Then, the image carrier 14 including an undercoat layer of 3.5 μm, a charge generation layer 75 of 0.15 μm, a charge transport layer 76 of 20 μm, and a protective layer 74 of 5 μm was produced. At this time, coating of the protective layer 74 was performed by a spray method, and other than that was performed by a dip coating method. The protective layer 74 was added with 25 wt% of alumina having an average particle size of 0.3 μm.
The developing unit 13 used a two-component developing system, and 0.15 wt% zinc stearate was added to the toner. The writing light L was laser light having a wavelength of 655 nm, and charging was performed by applying AC (2 kHz, 1.8 kVpp) + DC (−750 V) to the charging roller. The process speed is 125 mm / s. In such an electrophotographic process, durability was evaluated using three types of charts.
Chart 1 is a chart with an average image area ratio of 5% in which characters are arranged on average.
Chart 2 is a chart having an average image area ratio of 1.5% in which characters are arranged almost averagely.
Chart 3. A chart in which image data is arranged in the left half and characters are arranged in the right half. The left half has an average image area ratio of 20% and the right half has an average image area ratio of 1.5%. The average image area ratio is about 11%.
If there are areas where the average image area ratios H1 to H6 are 2% or less in each area divided into six areas in the direction perpendicular to the rotation direction of the image carrier (photosensitive body) 14, only that area is included. It was set to perform exposure development and to perform a lubricant supply operation.
Specifically, when there is a region where the average image area ratio in the region is 2% or less at the end of one job, a horizontal line of 4 dots of 600 dpi is set to 32 dots with respect to that region of the image carrier 14. Ten toners were exposed and developed at intervals, and toner and a lubricant were supplied onto the image carrier 14.

実施例５では図１に示したように、転写紙上に複数個配置されたフォトセンサ１０６により画像情報を読み取るので、フォトセンサ配置に際して設計レイアウト上の自由度が得られる。また、転写紙に最終的に転写定着された転写紙上の画像情報を取り込むことにより、異常画像のチェックや画像濃度の補正などにも情報をフィードバックすることが可能となる。 Under these conditions, five sheets were set for each job, and a total of 60,000 sheets were evaluated. In the case of Chart 1 (average image area ratio 5%), the wear amount of the image carrier 14 was about 1.8 μm, and about 12,000 images could be formed per toner bottle.
In the case of Chart 2 (average image area ratio 1.5%), the wear amount of the image carrier 14 was about 1.9 μm, and about 29,000 sheets of images could be formed per toner bottle.
In the case of chart 3 (the figure and characters are unevenly distributed, the average image area ratio of the entire chart is 11%), the wear amount of the image carrier 14 corresponding to the left side of the chart (average image area ratio of 20%) is 1.2 μm, the chart The amount of wear of the image carrier 14 corresponding to the right side (average image area ratio 1.5%) was 1.6 μm, and about 66,000 images could be formed per toner bottle. The image was good regardless of the image area ratio. One toner bottle contains 275 g of toner.
Table 4 summarizes the results of Example 5.

In the fifth embodiment, as shown in FIG. 1, image information is read by a plurality of photosensors 106 arranged on a transfer sheet, so that a degree of freedom in design layout can be obtained when the photosensors are arranged. Further, by taking in the image information on the transfer paper that is finally transferred and fixed on the transfer paper, it is possible to feed back the information to the check of the abnormal image and the correction of the image density.

<Comparative example 4>
In Comparative Example 4, 60,000 sheets were evaluated in the same manner as in Example 5 except that the lubricant supply operation was not executed in Example 5 regardless of the image area ratio. In the case of Chart 1 (average image area ratio 5%), the wear amount of the image carrier 14 was about 1.6 μm, and about 12,000 images could be formed per toner bottle.
In the case of Chart 2 (average image area ratio 1.5%), it was possible to form an image of about 30,000 sheets or more per toner bottle. However, the wear amount of the image carrier 14 was 4.8 μm, and the wear amount was about 4.8 μm. As a result, the protective layer 74 was partially lost. Also, vertical black streak-like stains were generated in the image.
In the case of chart 3 (the figure and characters are unevenly distributed, the average image area ratio of the entire chart is 11%), the wear amount of the image carrier 14 corresponding to the left side of the chart (average image area ratio of 20%) is 1.5 μm, the chart The wear amount of the image carrier 14 corresponding to the right side (average image area ratio 1.5%) is 4.1 μm, and the protective layer 74 is partially lost due to wear, and the image has vertical black stripes. It has occurred. About 88,000 images could be formed per toner bottle.

<Comparative Example 5>
In Comparative Example 5, in Example 5, when the average image area ratio of one chart is 2% or less, the lubricant supply operation is set to be performed on the entire surface, and 60,000 is performed in the same manner as in Example 5. The sheet was evaluated.
In the case of Chart 1 (average image area ratio 5%), the wear amount of the image carrier was about 1.6 μm, and about 11,000 sheets could be formed per toner bottle, and the image was good. In the case of Chart 2 (average image area ratio 1.5%), the wear amount of the image carrier 14 is about 1.9 μm, the image is good, and about 28,000 images can be formed per toner bottle. It was.
In the case of chart 3 (the figure and characters are unevenly distributed, the average image area ratio of the entire chart is 11%), the wear amount of the image carrier 14 is 1.5 μm at the right side of the chart (image area ratio of 20%), and the left side of the chart The portion corresponding to (image area ratio 1.5%) was 4.2 μm, and vertical black streak-like stains were generated on the image. About 77,000 images could be formed per toner bottle.

<Comparative Example 6>
In Comparative Example 6, when the image area ratios H1 to H6 of the region divided into six in Example 5 are 2% or less, the lubricant supply operation is set to be performed on the entire surface. In the same way, 60,000 sheets were evaluated.
In the case of Chart 1 (average image area ratio 5%), the wear amount of the image carrier was about 1.7 μm, and about 11,000 sheets could be formed per toner bottle, and the image was good. In the case of Chart 2 (average image area ratio 1.5%), the wear amount of the image carrier 14 is about 1.8 μm, the image is good, and about 27,000 images can be formed per toner bottle. It was. In the case of chart 3 (the figure and characters are unevenly distributed, the average image area ratio of the entire chart is 11%), the wear amount of the image carrier 14 is 1.4 μm at the right side of the chart (image area ratio of 20%), the left side of the chart The portion corresponding to (image area ratio 1.5%) was 1.8 μm, and no image abnormality was observed, but only about 4,000 images could be formed per toner bottle.
Table 5 summarizes the results of Comparative Examples 4 to 6.

<Example 6>
In the fifth embodiment, the image area ratio is calculated by reading the image on the transfer paper with a photosensor (CIS) and estimating the image area. However, the image area ratio may be detected on the image carrier. As shown in FIG. 2, six CISs 107 are arranged in series in the image carrier 14 at a position downstream of the developing roller 13 a of the developing unit 13 in the direction perpendicular to the rotation direction of the image carrier 14.
The toner developed on the image carrier 14 by the developing roller 13a is read by a photosensor (CIS) 107, and the image area is estimated from the light amount data, thereby calculating the image area ratio.
As a result, the image information can be calculated without imposing a load on the memory (CPU), so that it is possible to cope with the high speed of the printer, and the high durability of the image carrier 14 and the reduction in toner consumption can be achieved even in a high speed output printer. Can be planned. Further, the image formed on the image carrier 14 can be surely grasped by the photosensor 107, and the two-dimensional information of the image in the region difficult to grasp by the pixel count can be easily grasped.
Accordingly, it is possible to more accurately grasp the presence or absence of a solid image or a low image area portion and to perform fine lubricant supply. Further, by applying the photosensor 107 in a line at a position immediately before the transfer of the image carrier, the toner transferability and cleaning performance can be improved as in the pre-transfer exposure.
In the tandem color printer as in the present embodiment, it is necessary to dispose each image carrier, but each image carrier may be a monochrome sensor, and the toner developed on the image carrier is directly supplied. Since it can be read, more accurate image information can be obtained.

<Example 7>
In the fifth embodiment, the image area ratio is calculated by reading the image on the transfer paper with the photosensor CIS and estimating the image area. However, in the image forming apparatus having the intermediate transfer body 109, the image is detected on the intermediate transfer body 109. You may do it. As shown in FIG. 3, the image formed on the four-color image carrier 14 is temporarily transferred onto the intermediate transfer member 109 and further transferred onto the transfer paper by the secondary transfer roller 110.
The image area ratio is calculated from image information read by a plurality of photosensors 108 arranged on an intermediate transfer body 109 that is primarily transferred from the image carrier 14, and the image information can be obtained without imposing a load on the memory. It is possible to calculate, and it is possible to cope with the speeding up of the printer.
Further, even in a high-speed output printer, the durability of the image carrier and the toner consumption can be reduced. Since it is arranged on the intermediate transfer body 109, image information can be obtained without increasing the number of photosensors even in a printer in which a plurality of image carriers 14 are arranged, such as a tandem color printer. High durability of the body and reduction of toner consumption can be achieved.

1 is a schematic diagram illustrating an overall configuration of a small color printer as an example of an image forming apparatus according to the present invention. FIG. 2 is a schematic cross-sectional view showing an image carrier unit used in the color printer of FIG. 1. FIG. 2 is a schematic diagram illustrating a photosensor disposed on an intermediate transfer member of the image forming apparatus. It is a schematic block diagram which shows the writing unit used with the color printer of FIG. It is the schematic which shows the control block in the color printer of FIG. FIG. 2 is a partial cross-sectional view illustrating a configuration of an image carrier used in the color printer of FIG. 1. It is a fragmentary sectional view which shows the structure of the other image carrier. It is a block diagram which shows control of lubricant supply. It is a flowchart which shows an example of lubricant supply. 10 is a flowchart showing an example of determination of lubricant supply conditions in step (S7) of FIG. It is a flowchart which shows the other example of lubricant supply. It is the schematic which shows the photograph and figure arrange | positioned at the left half of a document, and the character arrange | positioned at the right half.

Explanation of symbols

  A image forming apparatus (printer main body), 10 monochrome image forming means, 12 image carrier unit, 13 developing unit (developing device), 14 image carrier, 16 writing unit (exposure unit), 45 cleaning blade, 74 protection Layer, 101 Image area calculation means, 104 Image area ratio calculation means, 105 Lubricant supply execution means, 106 Photo sensor (CIS), 107 Photo sensor (CIS), 108 Photo sensor (CIS), 109 Intermediate transfer member

Claims (9)

  An image forming apparatus comprising: an image carrier; an exposure unit that forms an electrostatic latent image on the image carrier; and a development unit that develops the electrostatic latent image of the image carrier using a developer. And image information calculating means for calculating image information for each area divided in a direction orthogonal to the rotation direction of the image carrier, separately from image formation for each area based on the image information for each area. An image forming apparatus that performs exposure and development.   The image forming apparatus according to claim 1, wherein the image information calculating unit calculates image area information with respect to a traveling area.   An image forming apparatus comprising: an image carrier; an exposure unit that forms an electrostatic latent image on the image carrier; and a development unit that develops the electrostatic latent image of the image carrier using a developer. An image information calculation means for calculating image information for each of the plurality of regions divided in a direction orthogonal to the rotation direction of the image carrier, and a determination for determining an exposure pattern for each region according to the average image information of each region An image forming apparatus, wherein exposure and development are performed separately from image formation.   An image forming apparatus comprising: an image carrier; an exposure unit that forms an electrostatic latent image on the image carrier; and a development unit that develops the electrostatic latent image of the image carrier using a developer. Image information calculation means for calculating image information for each of a plurality of regions divided in a direction orthogonal to the rotation direction of the image carrier, wherein the image information calculation means is configured to output the image in a direction perpendicular to the rotation direction. An image forming apparatus that calculates image information of each region from a photosensor arranged on a carrier.   5. The image information calculation unit calculates image information of each region from a photosensor disposed on an intermediate transfer member that primarily transfers toner developed on the image carrier. Image forming apparatus.   The image forming apparatus according to claim 4, wherein the image information calculation unit calculates image information of each region from a photosensor arranged on a transfer sheet in a direction orthogonal to the conveyance direction.   The image forming apparatus according to claim 1, wherein the developer contains a lubricant.   8. The image forming apparatus according to claim 1, further comprising a cleaning device that removes toner remaining on the image carrier with a cleaning blade.   9. The image forming apparatus according to claim 1, wherein an organic photoreceptor is used as the image carrier, and a protective layer containing a filler is provided on a surface of the organic photoreceptor.

Images