JP7056047B2 - Image forming device - Google Patents

Description

The present invention relates to an image forming apparatus.

In general, an image forming apparatus (printer, copier, facsimile, etc.) using electrophotographic process technology irradiates (exposes) a charged photoconductor drum (image carrier) with laser light based on image data. Form an electrostatic latent image. Then, by supplying toner from the developing device to the photoconductor drum on which the electrostatic latent image is formed, the electrostatic latent image is visualized and the toner image is formed. Further, after the toner image is directly or indirectly transferred to the paper, the toner image is formed on the paper by heating and pressurizing with the fixing nip to fix the toner image.

For example, Patent Document 1 discloses a technique for controlling the glossiness of the toner image surface on paper by forming an uneven pattern on the toner image surface by screen processing.

Japanese Unexamined Patent Publication No. 2012-145831

However, when the unevenness in the unevenness pattern becomes finer, when the paper on which the unevenness pattern is formed passes through the fixing nip, the surface of the fixing member cannot follow the fine unevenness, and the unevenness pattern is crushed by the fixing member. , The surface of the paper is smoothed. As a result, there arises a problem that the glossiness of the printed matter cannot be freely adjusted.

An object of the present invention is to provide an image forming apparatus capable of suppressing smoothing of an uneven pattern when the uneven pattern is formed on paper.

The image forming apparatus according to the present invention is
An image forming part that forms a toner image on paper,
A fixing portion having a fixing member that comes into contact with the toner image of the paper and fixes the toner image on the paper.
A control unit that controls the glossiness of the toner image surface on the paper by controlling the image forming unit so as to form an uneven toner image having unevenness on the paper.
Equipped with
The fixing member has a hardness that suppresses the crushing of the unevenness of the uneven toner image.
The micro hardness of the fixing member is 73 ° or more and 90 ° or less .
At least one of the width and depth of the unevenness of the uneven toner image is 30 μm or less .

According to the present invention, when an uneven pattern is formed on paper, it is possible to prevent the uneven pattern from being smoothed.

It is a figure which shows schematic the whole structure of the image forming apparatus which concerns on this embodiment. It is a figure which shows the main part of the control system of the image forming apparatus which concerns on this embodiment. It is a figure which shows an example of the unevenness pattern. It is a figure which shows an example of the unevenness pattern. It is a figure which shows an example of the unevenness pattern. It is a figure which shows an example of the unevenness pattern. It is a figure which shows an example of the unevenness pattern. It is a figure which shows the example which the unevenness pattern was formed in a plurality of image areas on a paper. It is a figure which shows the unevenness pattern on the paper before fixing. It is a figure which shows the unevenness pattern which is fixed by the conventional fixing belt. It is a figure which shows the unevenness pattern after being fixed by the conventional fixing belt. It is a figure which shows the unevenness pattern which is fixed by the fixing belt in this embodiment. It is a figure which shows the unevenness pattern after being fixed by the fixing belt in this embodiment. It is a figure which shows an example of the user selection screen in an operation part. It is a table that associates the type of paper, the basis weight, and the fixing temperature. It is a figure which shows the setting condition of a pressure by a load in a fixing nip, and a transport speed. It is a flowchart which shows an example of the operation example of glossiness control which concerns on an image forming apparatus. This is an experimental result when the width of the concave portion of the uneven pattern is changed for each fixing belt in which the micro hardness is changed. This is an experimental result when the depth of the concave portion of the uneven pattern is changed for each fixing belt in which the micro hardness is changed. It is an image pickup result of the toner image surface fixed by the fixing belt of the micro hardness 93 °. It is an image pickup result of the toner image surface fixed by the fixing belt of the micro hardness 90 °.

Hereinafter, the present embodiment will be described in detail with reference to the drawings. FIG. 1 is a diagram schematically showing an overall configuration of an image forming apparatus 1 according to the present embodiment. FIG. 2 is a diagram showing a main part of the control system of the image forming apparatus 1 according to the present embodiment.

As shown in FIG. 1, the image forming apparatus 1 is an intermediate transfer type color image forming apparatus using an electrophotographic process technique. That is, the image forming apparatus 1 primary transfers the Y (yellow), M (magenta), C (cyan), and K (black) color toner images formed on the photoconductor drum 413 to the intermediate transfer belt 421. After superimposing the toner images of four colors on the intermediate transfer belt 421, the image is formed by secondary transfer to the paper S sent from the paper feed tray units 51a to 51c.

Further, in the image forming apparatus 1, the photoconductor drums 413 corresponding to the four colors of YMCK are arranged in series in the traveling direction of the intermediate transfer belt 421, and the toner images of each color are sequentially transferred to the intermediate transfer belt 421 in one procedure. The tandem method is adopted.

As shown in FIG. 2, the image forming apparatus 1 includes an image reading unit 10, an operation display unit 20, an image processing unit 30, an image forming unit 40, a paper transport unit 50, a fixing unit 60, and a control unit 101.

The control unit 101 includes a CPU (Central Processing Unit) 102, a ROM (Read Only Memory) 103, a RAM (Random Access Memory) 104, and the like. The CPU 102 reads a program according to the processing content from the ROM 103, develops it in the RAM 104, and centrally controls the operation of each block of the image forming apparatus 1 in cooperation with the expanded program. At this time, various data stored in the storage unit 72 are referred to. The storage unit 72 is composed of, for example, a non-volatile semiconductor memory (so-called flash memory) or a hard disk drive.

The control unit 101 transmits / receives various data to / from an external device (for example, a personal computer) connected to a communication network such as a LAN (Local Area Network) or WAN (Wide Area Network) via the communication unit 71. conduct. The control unit 101 receives, for example, image data (input image data) transmitted from an external device, and causes the paper S to form an image based on the image data. The communication unit 71 is composed of a communication control card such as a LAN card.

As shown in FIG. 1, the image reading unit 10 includes an automatic document feeding device 11 called an ADF (Auto Document Feeder), a document image scanning device 12 (scanner), and the like.

The automatic document feeding device 11 conveys the document M placed on the document tray by the conveying mechanism and sends it out to the document image scanning device 12. The automatic document feeding device 11 makes it possible to continuously read a large number of images (including both sides) of the documents M placed on the document tray at once.

The document image scanning device 12 optically scans the document conveyed on the contact glass from the automatic document feeding device 11 or the document placed on the contact glass, and the reflected light from the document is a CCD (Charge Coupled Device). ) An image is formed on the light receiving surface of the sensor 12a, and the original image is read. The image reading unit 10 generates input image data based on the reading result of the original image scanning device 12. Predetermined image processing is performed on the input image data by the image processing unit 30.

As shown in FIG. 2, the operation display unit 20 is composed of, for example, a liquid crystal display (LCD: Liquid Crystal Display) with a touch panel, and functions as a display unit 21 and an operation unit 22. The display unit 21 displays various operation screens, image states, operation statuses of each function, and the like according to the display control signal input from the control unit 101. The operation unit 22 includes various operation keys such as a numeric keypad and a start key, receives various input operations by the user, and outputs an operation signal to the control unit 101.

The image processing unit 30 includes a circuit or the like that performs digital image processing according to initial settings or user settings for input image data. For example, the image processing unit 30 performs gradation correction based on the gradation correction data (gradation correction table) under the control of the control unit 101. Further, the image processing unit 30 performs various correction processes such as color correction and shading correction, compression processing, and the like, in addition to gradation correction, on the input image data. The image forming unit 40 is controlled based on the image data subjected to these processes.

As shown in FIG. 1, the image forming unit 40 has image forming units 41Y, 41M, 41C for forming an image with each colored toner of Y component, M component, C component, and K component based on the input image data. , 41K, intermediate transfer unit 42 and the like.

The image forming units 41Y, 41M, 41C, 41K for the Y component, the M component, the C component, and the K component have the same configuration. For convenience of illustration and description, common components are indicated by the same reference numerals, and when distinguishing between them, the reference numerals are given with Y, M, C, or K. In FIG. 1, reference numerals are given only to the components of the image forming unit 41Y for the Y component, and the reference numerals are omitted for the other components of the image forming units 41M, 41C, and 41K.

The image forming unit 41 includes an exposure device 411, a developing device 412, a photoconductor drum 413, a charging device 414, a drum cleaning device 415, and the like as an example of the exposure unit.

The photoconductor drum 413 is made of an organic photoconductor in which, for example, a photosensitive layer made of a resin containing an organic photoconductor is formed on an outer peripheral surface of a drum-shaped metal substrate.

The control unit 101 rotates the photoconductor drum 413 at a constant peripheral speed by controlling the drive current supplied to the drive motor (not shown) that rotates the photoconductor drum 413.

The charging device 414 is, for example, a charging charger, and by generating a corona discharge, the surface of the photoconductor drum 413 having photoconductivity is uniformly charged to a negative electrode.

The exposure apparatus 411 is composed of, for example, a semiconductor laser, and irradiates the photoconductor drum 413 with a laser beam corresponding to an image of each color component. As a result, an electrostatic latent image of each color component is formed in the image region irradiated with the laser beam on the surface of the photoconductor drum 413 due to the potential difference from the background region.

The developing device 412 is a two-component reversing type developing device, and a toner image is formed by visualizing an electrostatic latent image by adhering a developer of each color component to the surface of the photoconductor drum 413.

For example, a DC development bias having the same polarity as the charging polarity of the charging device 414 or a development bias in which a DC voltage having the same polarity as the charging polarity of the charging device 414 is superimposed on the AC voltage is applied to the developing device 412. As a result, reverse development is performed in which toner is adhered to the electrostatic latent image formed by the exposure apparatus 411.

The drum cleaning device 415 has a flat plate-shaped drum cleaning blade or the like which is abutted against the surface of the photoconductor drum 413 and is made of an elastic body, and remains on the surface of the photoconductor drum 413 without being transferred to the intermediate transfer belt 421. Remove the toner.

The intermediate transfer unit 42 includes an intermediate transfer belt 421, a primary transfer roller 422, a plurality of support rollers 423, a secondary transfer roller 424, a belt cleaning device 426, and the like.

The intermediate transfer belt 421 is composed of an endless belt and is stretched in a loop on a plurality of support rollers 423. At least one of the plurality of support rollers 423 is composed of a driving roller, and the other is composed of a driven roller. For example, it is preferable that the roller 423A arranged on the downstream side in the belt traveling direction with respect to the primary transfer roller 422 for the K component is the drive roller. This makes it easier to keep the running speed of the belt in the primary transfer unit constant. As the drive roller 423A rotates, the intermediate transfer belt 421 travels at a constant speed in the direction of arrow A.

The intermediate transfer belt 421 is a belt having conductivity and elasticity, and has a high resistance layer on the surface. The intermediate transfer belt 421 is rotationally driven by a control signal from the control unit 101.

The primary transfer roller 422 is arranged on the inner peripheral surface side of the intermediate transfer belt 421 so as to face the photoconductor drum 413 of each color component. The primary transfer roller 422 is pressed against the photoconductor drum 413 with the intermediate transfer belt 421 interposed therebetween, thereby forming a primary transfer nip for transferring the toner image from the photoconductor drum 413 to the intermediate transfer belt 421.

The secondary transfer roller 424 is arranged on the outer peripheral surface side of the intermediate transfer belt 421 so as to face the backup roller 423B arranged on the downstream side of the drive roller 423A in the belt traveling direction. The secondary transfer roller 424 is pressed against the backup roller 423B with the intermediate transfer belt 421 interposed therebetween, thereby forming a secondary transfer nip for transferring the toner image from the intermediate transfer belt 421 to the paper S.

When the intermediate transfer belt 421 passes through the primary transfer nip, the toner image on the photoconductor drum 413 is sequentially superimposed on the intermediate transfer belt 421 and the primary transfer is performed. Specifically, a primary transfer bias is applied to the primary transfer roller 422, and a charge having a polarity opposite to that of the toner is applied to the back surface side of the intermediate transfer belt 421, that is, the side in contact with the primary transfer roller 422. It is electrostatically transferred to the intermediate transfer belt 421.

After that, when the paper S passes through the secondary transfer nip, the toner image on the intermediate transfer belt 421 is secondarily transferred to the paper S. Specifically, the toner image is obtained by applying a secondary transfer bias to the secondary transfer roller 424 and applying a charge having the opposite polarity to the toner on the back surface side of the paper S, that is, the side in contact with the secondary transfer roller 424. Is electrostatically transferred to the paper S. The paper S on which the toner image is transferred is conveyed toward the fixing portion 60.

The belt cleaning device 426 removes the transfer residual toner remaining on the surface of the intermediate transfer belt 421 after the secondary transfer.

The fixing portion 60 is arranged on the fixing surface of the paper S, that is, the upper fixing portion 60A having the fixing surface side member arranged on the surface side on which the toner image is formed, and the back surface of the paper S, that is, on the opposite surface side of the fixing surface. It is provided with a lower fixing portion 60B having a back surface side support member, a heating source, and the like. By pressing the back surface side support member against the fixing surface side member, a fixing nip that sandwiches and conveys the paper S is formed.

The fixing unit 60 secondarily transfers the toner image and heats and pressurizes the conveyed paper S with the fixing nip to fix the toner image on the paper S. The fixing portion 60 is arranged as a unit in the fixing device F.

The upper fixing portion 60A has an endless fixing belt 61, a heating roller 62, and a fixing roller 63, which are members on the fixing surface side. The fixing belt 61 is stretched by a heating roller 62 and a fixing roller 63. The fixing belt 61 corresponds to the "fixing member" of the present invention.

The fixing roller 63 in the present embodiment exemplifies a sponge having a diameter of 60 mm, a thickness of 15 mm, and a cell diameter of 30 μm. The hardness of the fixing roller 63 is, for example, Asker C hardness of 30 °.

The lower fixing portion 60B has a pressure roller 64 which is a back surface side support member. The pressure roller 64 forms a fixing nip that sandwiches and conveys the paper S with the fixing belt 61.

The pressure roller 64 in the present embodiment has a diameter of 60 mm and a thickness of 2 mm, and exemplifies those made of silicon rubber and a surface layer PFA tube. The hardness of the pressure roller 64 is, for example, a JISA hardness of 30 °.

The paper transport unit 50 includes a paper feed unit 51, a paper discharge unit 52, a transport path unit 53, and the like. Paper S (standard paper, special paper) identified based on the basis weight, size, etc. is stored in the three paper feed tray units 51a to 51c constituting the paper feed unit 51 for each preset type. .. The transport path portion 53 has a plurality of transport roller pairs including a resist roller pair 53a. The resist roller portion in which the resist roller pair 53a is arranged corrects the inclination and deviation of the paper S.

The paper S housed in the paper feed tray units 51a to 51c is sent out one by one from the uppermost portion, and is conveyed to the image forming unit 40 by the transfer path unit 53. In the image forming unit 40, the toner image of the intermediate transfer belt 421 is collectively secondarily transferred to one surface of the paper S, and the fixing step is performed in the fixing unit 60. The image-formed paper S is discharged to the outside of the machine by the paper ejection unit 52 provided with the paper ejection roller 52a.

Further, in the present embodiment, in order to adjust the glossiness of the toner image surface formed on the paper S, the control unit 101 controls the image forming unit 40 so as to form a predetermined uneven pattern on the toner image surface. .. The uneven pattern is an uneven toner image having unevenness.

Specifically, the control unit 101 controls the image forming unit 40 so as to form a plurality of types of uneven patterns according to the image forming conditions. The plurality of types of uneven patterns are formed by adjusting the exposure amount of the exposure apparatus 411.

As the uneven pattern, for example, as shown in FIGS. 3A to 3E, the density of the predetermined toner image T formed at a predetermined density is different from the density of the predetermined toner image T in the region where the predetermined toner image T is formed. An example is a pattern provided with a recessed portion D.

A plurality of recessed portions D are provided in the region of the predetermined toner image T, and a step, that is, unevenness is formed between the recessed portion D and the predetermined toner image T. It should be noted that FIGS. 3A to 3E exemplify an example in which five recesses D are formed in the region of the predetermined toner image T.

For example, no toner image is formed in the substantially square recessed portion D1 shown in FIG. 3A. Further, the recessed portion D1 shown in FIG. 3A has a size corresponding to one dot, and has a width and a depth of 30 μm or less.

Further, in the recessed portion D2 shown in FIG. 3B, a toner image having a density smaller than that of the predetermined toner image T is formed. Therefore, the unevenness of the unevenness pattern shown in FIG. 3B is shallower than the unevenness of the unevenness pattern shown in FIG. 3A.

Since there is no toner image in the concave portion D1 of the uneven pattern as shown in FIG. 3A and a deep concave is formed, the unevenness is hard to be crushed, but the ground color of the paper S may be visible, so that the density is lowered or the density is reduced. Unevenness is likely to occur. On the other hand, the concave portion D2 of the uneven pattern as shown in FIG. 3B forms a toner image having a density smaller than that of the toner image T by weakening the exposure amount of the exposure apparatus 411 to be smaller than that of the toner image T portion. Therefore, the recessed portion D2 has a shallow recess, but since the toner image is formed, the density decrease and the density unevenness in the vicinity of the recessed portion D1 in FIG. 3A can be suppressed to the minimum.

Further, the recessed portion D3 shown in FIG. 3C is obtained by substantially dividing the recessed portion D1 shown in FIG. 3A into two parts. That is, the uneven pattern shown in FIG. 3C has finer unevenness than the uneven pattern shown in FIG. 3A.

Further, in the uneven pattern shown in FIG. 3D, a concave portion D1 and a convex portion C adjacent to the concave portion D1 are provided, respectively. The recessed portion D1 is the same as the recessed portion D1 shown in FIG. 3A, and a toner image having a density higher than that of the predetermined toner image T is formed in the convex portion C. Therefore, in the uneven pattern shown in FIG. 3D, unevenness is formed between the concave portion D1, the predetermined toner image T, and the convex portion C.

Further, in the uneven pattern shown in FIG. 3E, different concave portions are formed at five points in the region of the predetermined toner image T. The recessed portion D4 at the upper left position and the recessed portion D5 at the substantially central position in the predetermined toner image T of FIG. 3E are obtained by dividing the recessed portion D1 shown in FIG. 3A into four, but the shape of the portion without the toner image. Are different from each other. The recessed portion D4 has a rectangular shape in a portion without a toner image, and the recessed portion D5 has a triangular shape in a portion without a toner image.

The recessed portion D2 at the upper right position in the predetermined toner image T is the same as the recessed portion D2 shown in FIG. 3B, and the recessed portion D1 and the convex portion C at the lower left position are the recessed portion D1 and the convex portion C shown in FIG. 3D. Is similar to. Further, the recessed portion D6 at the lower right position in the predetermined toner image T is a recessed portion D2 divided into two.

Further, as shown in FIG. 3F, when the image region B has a plurality of regions, the control unit 101 may form any of the uneven patterns shown in FIGS. 3A to 3E in each region. FIG. 3F shows an example in which the uneven pattern shown in FIG. 3A and the uneven pattern shown in FIG. 3D are formed in two image regions on paper. This makes it possible to control the glossiness for each image area B.

By properly using a plurality of types of uneven patterns in this way, it is possible to freely adjust the glossiness on the surface of the toner image. However, as the unevenness in the unevenness pattern becomes finer or the dent becomes shallower, when the surface of the fixing belt 61 is made of a relatively hard material, the surface of the fixing belt 61 is less likely to be deformed. May not be able to follow.

Specifically, for example, as shown in FIG. 4A, when the uneven pattern is formed on the paper S before fixing, the recessed portion D is formed on the toner image T formed on the paper S. However, as shown in FIG. 4B, when the paper S passes through the fixing nip, the surface of the fixing belt 61 is deformed along the recessed portion D and does not enter, and the toner image T around the recessed portion D is displayed on one side. Will be crushed.

As a result, as shown in FIG. 4C, the flat toner image T1 is fixed on the paper S. That is, there arises a problem that the surface of the toner image of the paper S is smoothed. In this case, the diffused reflection of light on the surface of the toner image is reduced, and the surface of the toner image has a high glossiness, so that the glossiness cannot be freely adjusted.

Therefore, in the present embodiment, the fixing belt 61 has a hardness that suppresses the crushing of the unevenness of the unevenness pattern. The hardness at which the unevenness of the unevenness pattern is suppressed is such that the fixing belt 61 is deformed so as to follow the unevenness shape of the unevenness pattern, and the microhardness is 90 ° or less.

An example of the fixing belt 61 of the present embodiment is a polyimide substrate having a diameter of 99 mm and a thickness of 70 μm, a silicon rubber having a thickness of 200 μm, and a PFA tube as a surface layer.

As a result, as shown in FIG. 5, the surface of the fixing belt 61 enters the recessed portion D. That is, since the fixing belt 61 follows the unevenness of the unevenness pattern, the toner image T can be fixed on the paper S without crushing the concave portion D. As a result, as shown in FIG. 6, the recessed portion D can be left in the toner image T1 after fixing.

Therefore, for example, even in the case of an uneven pattern having a relatively small step as shown in FIG. 3B, the recessed portion D can be reliably left, so that desired glossiness control can be performed.

Further, the control unit 101 may control the image forming unit 40 according to the glossiness information input by the user from the operation unit 22, for example. For example, a case where the operation unit 22 is composed of an operation panel as shown in FIG. 7 will be described as an example of control.

As shown in FIG. 7, on the operation panel, the glossiness level can be selected by the user in each of the character portion constituting the character and the solid solid portion representing the portion where the toner is concentrated in the image area. The operation screen is displayed.

In FIG. 7, "low" indicates a relatively low level of gloss, "high" indicates a relatively high level of gloss, and "medium" is a level between "low" and "high". The glossiness of, which mainly indicates the level of glossiness set by default.

For example, when the user selects a medium-level glossiness for the character portion and a low-level glossiness for the solid solid portion, the control unit 101 acquires the glossiness information and based on the glossiness information. The image forming unit 40 is controlled. As a result, the glossiness desired by the user can be adjusted.

By the way, the glossiness is easily affected by the thickness of the paper, the surface shape, and the like. In the case of thick paper, since the heat capacity is large, the heat when the toner image is fixed on the paper S is easily taken away by the paper S, and in the case of a paper having a relatively rough surface, it enters the dents in the uneven portion of the surface. However, heat is not easily transferred to the toner.

In the case of such paper S, the toner is not completely melted or is difficult to be smoothed, so that the glossiness is relatively low. Therefore, with such a paper S, excessive low glossiness and deterioration of image quality occur by controlling the glossiness.

Therefore, the control unit 101 may automatically control the glossiness based on the image information and the type of the paper S. Examples of the image information include characters and solid solids. Examples of the type of paper S include various types such as plain paper and embossed paper.

Further, even if the same type of paper S is used, the basis weight, surface roughness and smoothness are different, so it is preferable to control the glossiness in consideration of these parameters. Therefore, the control unit 101 may determine whether or not to control the glossiness according to the basis weight of the paper S, the surface roughness of the paper S, and the smoothness of the surface of the paper S. ..

For example, in the control unit 101, the basis weight of the paper S is a predetermined amount (for example, 62 g / m ³ ) or more, the type of the paper S is, for example, book paper, rough paper or embossed paper, and the paper S. If the smoothness falls under any of a predetermined degree (for example, 11 seconds) or more, it is determined that the glossiness control is not executed. By doing so, it is possible to suppress excessive reduction in glossiness and deterioration of image quality.

Further, the control unit 101 changes at least one of the heating temperature of the fixing belt 61, the load on the fixing nip, and the conveying speed of the paper S on the fixing belt 61, depending on the type of the paper S.

For example, the control unit 101 determines the heating temperature of the fixing belt 61, the load at the fixing nip, and the transport speed of the paper S on the fixing belt 61 with reference to FIGS. 8 and 9. The "Beck smoothness" in FIG. 8 will be described simply as "smoothness" in the following description. Further, "pressure" in FIG. 9 indicates the pressure due to the load at the fixing nip, and "speed" indicates the conveying speed of the paper S in the fixing belt 61.

Specifically, the control unit 101 determines the heating temperature of the fixing belt 61 with reference to FIG. In FIG. 8, the paper S is plain paper having a basis weight in the range of 75 to 216 g / m ² , book paper having a basis weight in the range of 75 to 135 g / m ² , and has a basis weight of 75 to 91 g. For rough paper in the range of / m ² , the heating temperature is set to 200 ° C., and under other conditions, the heating temperature is set to 195 ° C.

Then, the control unit 101 determines the load at the fixing nip and the transport speed of the paper S on the fixing belt 61 by comparing each condition in FIG. 8 with the fixing condition shown in FIG. The fixing conditions are, for example, the conditions from the first condition to the fifth condition shown in FIG.

The first condition is that the pressure due to the load is the smallest and the transport speed is the highest. In the second condition, the pressure due to the load is larger than that in the first condition, and the transport speed is the same as that in the first condition.

In the third condition, the pressure due to the load is larger than that in the second condition, and the transport speed is the same as that in the second condition. In the fourth condition, the pressure due to the load is the same as that in the third condition, and the transport speed is smaller than that in the third condition. In the fifth condition, the pressure due to the load is the same as that in the fourth condition, and the transport speed is smaller than that in the fourth condition.

Further, the conditions for coated paper, woodfree paper and plain paper having a basis weight of 40 to 49 g / m ² in FIG. 8 are set as the first condition. The conditions for the coated paper and the woodfree paper in the range of the basis weight of 50 to 105 g / m ² in FIG. 8 are set as the second condition.

In FIG. 8, coated paper having a basis weight of 106 to 162 g / m ² , high-quality paper having a basis weight of 106 to 216 g / m ² , plain paper having a basis weight of 50 to 216 g / m ² , and a book having a basis weight of 40 to 91 g / m ² . The conditions for the paper, the rough paper having a basis weight of 40 to 80 g / m ² , and the embossed paper having a basis weight of 40 to 61 g / m ² are set as the third condition.

High-quality paper with a basis weight of 217 to 256 g / m ² in FIG. 8, book paper with a basis weight of 92 to 135 g / m ² , rough paper with a basis weight of 81 to 91 g / m ² , and embossed paper with a basis weight of 62 to 74 g / m ² . The condition of is set to the fourth condition.

In FIG. 8, coated paper having a basis weight of 163 to 350 g / m ² , high-quality paper having a basis weight of 257 to 350 g / m ² , plain paper having a basis weight of 217 to 350 g / m ² , and a book having a basis weight of 136 to 350 g / m ² . The conditions for the paper, the rough paper having a basis weight of 92 to 350 g / m ² , and the embossed paper having a basis weight of 75 to 350 g / m ² are set as the fifth condition.

As described above, the larger the basis weight of the paper and the smaller the smoothness, the larger the pressure due to the load and the lower the transport speed so that heat can be easily transferred to the toner image. That is, by setting the heating temperature, the fixing load, and the transport speed suitable for the type of paper as shown in FIGS. 8 and 9, the fixing conditions can be set according to the type of paper.

Further, the control unit 101 may control the glossiness with reference to FIG. For example, the control unit 101 determines that the glossiness control is not executed under the condition surrounded by the broken line in FIG. 8, which is a condition where the basis weight is relatively high and the smoothness is small, and other than that. It may be decided to execute the control of the glossiness under the condition of.

Next, an operation example when executing the glossiness control in the image forming apparatus 1 will be described. FIG. 10 is a flowchart showing an example of an operation example of glossiness control according to the image forming apparatus 1. The process in FIG. 10 is executed when the control unit 101 receives an execution instruction for the print process.

As shown in FIG. 10, the control unit 101 acquires paper information (step S101). Next, the control unit 101 sets the fixing conditions according to the acquired paper information (step S102).

Next, the control unit 101 determines whether or not to execute the glossiness control according to the paper information, that is, the type of paper (step S103). As a result of the determination, when the glossiness control is not executed (step S103, NO), the process proceeds to step S105.

On the other hand, when the glossiness control is executed (step S103, YES), the control unit 101 selects the optimum unevenness pattern from a plurality of types of unevenness patterns (step S104). Next, the control unit 101 executes an image forming process (step S105). After step S105, this control ends.

According to the present embodiment as described above, when the uneven pattern is formed on the paper S, the fixing belt 61 is inserted into the concave portion D of the uneven pattern. In particular, even in the case of the recessed portion D2 having a relatively shallow depth as shown in FIG. 3B, the fixing belt 61 firmly enters the recessed portion D2.

Therefore, since the toner image T can be fixed on the paper S while maintaining the shape of the recessed portion D, it is possible to prevent the unevenness pattern from being smoothed. As a result, the glossiness of the printed matter can be freely adjusted.

By the way, in order to maintain the shape of the recessed portion D, for example, a configuration is conceivable in which the recessed portion D is not crushed by using transparent toner or the like. In such a configuration, since the developing device 412 for transparent toner is required, the image forming device 1 may become large in size.

However, in the present embodiment, since the fixing belt 61 is inserted into the recessed portion D, it is not necessary to use transparent toner. Therefore, the glossiness of the toner image surface on the paper S can be controlled without increasing the size of the image forming apparatus 1.

In the above embodiment, the fixing belt 61 is exemplified as the fixing member, but the present invention is not limited to this, and for example, in the case of a roller fixing type fixing portion, a roller constituting the upper fixing portion may be used. ..

In addition, the above embodiments are merely examples of embodiment of the present invention, and the technical scope of the present invention should not be construed in a limited manner by these. That is, the present invention can be implemented in various forms without departing from its gist or its main features.

Finally, an evaluation experiment of the image forming apparatus 1 according to the present embodiment will be described. First, in the image forming apparatus 1 shown in FIG. 1, the glossiness of the surface of the toner image formed on the paper is measured for each fixing belt 61 by using a plurality of fixing belts 61 having different macro hardness, and the surface thereof is measured. It was confirmed whether or not was smoothed.

The experimental conditions were that the ambient temperature of the image forming apparatus 1 was 20 ° C., the humidity was 50% RH, and the paper had a basis weight of 186 g / m ² (Sunmat, manufactured by Hokuetsu Kishu Paper Co., Ltd.). The image formed in was a solid blue image. The measurement angle with a gloss meter (MULTI GLOSS 268Plus, manufactured by Konica Minolta Co., Ltd.) was set to 60 °.

Further, as the fixing belt 61, a belt whose micro hardness was measured by a micro rubber hardness tester (MD-1capa, manufactured by Polymer Meter Co., Ltd.) was used, and a belt having a micro hardness in the range of 73 to 93 ° was used. ..

FIG. 11 shows the experimental results when the width of the concave portion of the uneven pattern is changed for each fixing belt 61 having different micro hardness. FIG. 12 shows the experimental results when the depth of the concave portion of the uneven pattern is changed for each fixing belt 61 having different micro hardness. The horizontal axis in FIGS. 11 and 12 indicates the fixing belt 61 having a different micro hardness in terms of micro hardness. Further, when the measured glossiness was 35 ° or less, it was determined that the surface of the toner image was not smoothed, and when the glossiness was 36 ° or more, it was determined that the surface of the toner image was smoothed.

The black circles in FIGS. 11 and 12 indicate that the glossiness was in the range of 15 to 25 °, and the white circles indicate that the glossiness was in the range of 26 to 30 °. The triangles in FIGS. 11 and 12 indicate that the glossiness was in the range of 31 to 35 °, and the cross indicates that the glossiness was 36 ° or more.

As shown in FIGS. 11 and 12, in the case of the fixing belt 61 having a micro hardness of 93 °, when the width or depth of the recess is less than 30 μm, the glossiness gradually increases and the smoothing tends to be easy. Can be confirmed. It can be confirmed that the unevenness is small even by looking at the result of imaging by the scanning electron microscope shown in FIG.

On the other hand, as shown in FIGS. 11 and 12, in the case of the fixing belt 61 having a micro hardness of 90 ° or less, it can be confirmed that the fixing belt 61 is not smoothed even when the width or depth of the recessed portion is less than 30 μm. Looking at the results of imaging with the scanning electron microscope shown in FIG. 14, it can be confirmed that a dent for one toner (length 5 to 15 μm, width 5 to 15 μm, depth 5 to 15 μm) remains. Note that FIGS. 13 and 14 show a scanning electron microscope with a magnification of 1000 times.

From this, it was confirmed that the surface of the toner image was not smoothed when the micro hardness of the fixing belt 61 was 90 ° or less, and the effectiveness of the present invention was confirmed.

Further, it was confirmed that the thickness of the fixing belt 61 tends to increase as the micro hardness of the fixing belt 61 becomes smaller. Table 1 shows the thickness of the fixing belt 61 for each micro hardness.

It was confirmed that when the micro-hardness of the fixing belt 61 was 73 °, that is, the thickness of the fixing belt 61 was 550 μm, it took time for the fixing belt 61 to raise the temperature, and as a result, electric power was applied. It is considered that this is because the thicker the fixing belt 61, the larger the heat capacity. Therefore, it is considered preferable that the micro-hardness of the fixing belt 61 is 73 ° or more from the viewpoint of energy saving.

1 Image forming device 22 Operation unit 40 Image forming unit 60 Fixing unit 61 Fixing belt 101 Control unit 411 Exposure device

Claims (8)

An image forming part that forms a toner image on paper,
A fixing portion having a fixing member that comes into contact with the toner image of the paper and fixes the toner image on the paper.
A control unit that controls the glossiness of the toner image surface on the paper by controlling the image forming unit so as to form an uneven toner image having unevenness on the paper.
Equipped with
The fixing member has a hardness that suppresses the crushing of the unevenness of the uneven toner image.
The micro hardness of the fixing member is 73 ° or more and 90 ° or less .
At least one of the width and depth of the unevenness of the uneven toner image is 30 μm or less.
Image forming device. The control unit controls the image forming unit so as to form a plurality of types of the uneven toner images.
The image forming apparatus according to claim 1. The image forming portion has an exposed portion that exposes an image carrier on which the toner image is supported.
The control unit controls the image forming unit so as to form the uneven toner image by adjusting the exposure amount of the exposed unit.
The image forming apparatus according to claim 2 . When there are a plurality of image regions on the paper, the control unit controls the image forming unit so as to form an uneven toner image for each image region.
The image forming apparatus according to claim 2 or 3 . Equipped with an operation unit for the user to select and operate the glossiness of the toner image.
The control unit controls the image forming unit according to the glossiness input by the operation unit.
The image forming apparatus according to any one of claims 1 to 4 . The control unit controls the image forming unit so as to automatically control the glossiness based on the image information and the type of paper.
The image forming apparatus according to any one of claims 1 to 5 . The control unit determines whether or not to control the glossiness according to the basis weight of the paper, the surface roughness of the paper, and the smoothness of the paper surface.
The image forming apparatus according to any one of claims 1 to 6 . The control unit changes at least one of the heating temperature of the fixing member, the load on the fixing member, and the transport speed of the paper on the fixing member, depending on the type of the paper.
The image forming apparatus according to any one of claims 1 to 7 .

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