JP2023131420A - Transparent toner processing apparatus, image forming apparatus, transparent toner processing method, and transparent toner processing program - Google Patents

Abstract

To decrease the glossiness of an edge part to make inconspicuous the difference in level of glossiness.SOLUTION: An image forming apparatus 1 comprises: an image forming unit 20T that forms a transparent toner image on a recording medium; and a transparent toner processing section 131 that performs processing of placing transparent toner on an edge part of an image area of a toner image on a printing sheet. In the printing sheet having the transparent toner placed thereon by the image forming unit 20T, the transparent toner is placed from the edge part of the image area, and the number of dots at the edges of a transparent toner area and a non-image area is reduced compared with the other areas.SELECTED DRAWING: Figure 1

Description

The present invention relates to a transparent toner processing apparatus, an image forming apparatus, a transparent toner processing method, and a transparent toner processing program.

2. Description of the Related Art Conventionally, image forming apparatuses called multifunction peripherals have been installed in offices. A multifunction peripheral has, for example, a printing function, a copying function, a scanning function, and the like. A multifunction device prints an image on printing paper by transferring the image to printing paper, which is a recording medium. For example, when a multifunction device prints with an adhesion amount of 2.0 g/m ² or more, a difference in gloss may occur between a high-density area and a low-density area.

The summary of Patent Document 1 states, ``Four developing devices 4a, 4b, 4c, and 4d contain cyan, magenta, yellow, and transparent toner, respectively, and a toner image is formed on the image carrier 1 by each developing device. The image processing device 22 calculates the difference in the total amount of developed toner for each pixel between adjacent pixels of the color image, and when this difference exceeds a predetermined value, a transparent area is created around the pixel with a large amount of developed toner. A toner image is formed. By setting the range in which this transparent toner is formed, the amount of toner transfer, and the fixing conditions, the inclination angle of the toner layer in the toner image fixed on the recording medium is set to 1.5 degrees or less. Adjust accordingly.''

Japanese Patent Application Publication No. 2001-83760

According to the invention described in Patent Document 1, an electrophotographic color image forming apparatus has a moderate gloss similar to that of a silver salt photograph, and the boundary between a high-density area and a low-density area is difficult to recognize. , it is possible to form a color image with good graininess.

However, in the image forming apparatus disclosed in Patent Document 1, the transparent toner is arranged parallel to the edge in order to reduce the difference in gloss between the high adhesion amount and the low adhesion amount. Therefore, a difference in gloss between the transparent toner and the toner and a difference in the gloss between the transparent toner and the recording medium physically occur.

The present invention has been made in view of the above-mentioned problems, and provides a transparent toner processing device, an image forming device, a transparent toner processing method, and a transparent toner processing program that blur the gloss of the edge portion and make the difference in gloss less noticeable. The challenge is to provide the following.

That is, the above-mentioned problems of the present invention are solved by the following configuration.

(1) an image forming section that forms a transparent toner image on a recording medium;
a transparent toner processing unit that performs processing to place transparent toner on an edge portion of an image area of the toner image on the recording medium;
Equipped with
In the recording medium on which the image forming section has placed transparent toner, the transparent toner is placed from the edge portion of the image area, and the number of dots at the edge of the transparent toner area and the non-image area is reduced compared to other areas. has been,
A transparent toner processing device characterized by:

(2) The recording medium on which the image forming section has placed the transparent toner has edges between the transparent toner area and the non-image area on the recording medium being blurred by area gradation.
The transparent toner processing device according to (1), characterized in that:

(3) The recording medium on which the image forming section has placed transparent toner has transparent toner placed on edge portions of line image and/or solid image areas on the recording medium.
The transparent toner processing device according to (1) or (2), characterized in that:

(4) The recording medium on which the image forming section has placed the transparent toner has a mode in which the edge portion of the dot image area on the recording medium is different from the edge portion of the line image and/or solid image area. Contains clear toner,
The transparent toner processing device according to any one of (1) to (3).

(5) The recording medium on which the image forming section has placed transparent toner has transparent toner also placed on the image area on the recording medium.
The transparent toner processing device according to any one of (1) to (4).

(6) The recording medium on which the image forming section has placed the transparent toner has a dot number and/or range of the transparent toner adjusted from the non-image area to the image area on the recording medium.
The transparent toner processing device according to item (5).

(7) The recording medium on which the image forming section has placed the transparent toner has the transparent toner placed in a predetermined range from the edge of the image area on the recording medium toward the non-image area.
The transparent toner processing device according to any one of (1) to (6), characterized in that:

(8) The area on which the transparent toner is placed on the recording medium on which the image forming section places the transparent toner is changed based on the size of dots in the image area on the recording medium.
The transparent toner processing device according to (4), characterized in that:

(9) When the recording medium on which the image forming unit has placed transparent toner has any of the dot size, line width thickness, and solid patch size of the image area on the recording medium equal to or larger than a threshold value; does not contain transparent toner,
The transparent toner processing device according to (8), characterized in that:

(10) The recording medium on which the transparent toner is placed by the image forming section determines the number and range of dots on which the transparent toner is placed, based on the difference in gloss between the transparent toner on the recording medium and the toner in the image area. has been adjusted,
The transparent toner processing device according to any one of (1) to (9).

(11) comprising an image reading unit that reads the transparent toner formed on the recording medium and the toner in the image area and detects a difference in gloss between the transparent toner and the toner in the image area;
The transparent toner processing device according to item (10).

(12) The image forming section determines whether or not the transparent toner is placed on the edge of the image area, and whether or not the transparent toner is placed on the edge of the image area, according to image attribute information indicating the printing type. Either the number of dots of the transparent toner placed on the transparent toner or the use range of the transparent toner is adjusted.
The transparent toner processing device according to any one of (1) to (11).

(13) The recording medium on which the image forming section has placed the transparent toner may determine whether the transparent toner is placed on the edge of the image area or not, depending on the printing rate information of the toner image on the recording medium. Either the number of dots of transparent toner placed on the edge of the image area or the usage range of the transparent toner is adjusted;
The transparent toner processing device according to any one of (1) to (12), characterized in that:

(14) an image processing unit that processes edges of image data;
further comprising: the transparent toner processing section according to any one of claims 1 to 13;
The image forming unit further forms an image area of a toner image on the recording medium,
The transparent toner processing section includes:
Based on the edge processing of the image data by the image processing unit, determining whether to place transparent toner on the edge of the image area, the number of dots of transparent toner to be placed on the edge of the image area, and the size of the transparent toner area. adjust any
An image forming apparatus characterized by:

(15) The image forming section includes:
forming one or more types of toner images on the recording medium;
The image forming apparatus according to (14), characterized in that:

(16) comprising a media sensor that determines the type of the recording medium;
The transparent toner processing section includes:
Depending on the glossiness of the recording medium determined by the media sensor, whether or not to place the transparent toner on the edge of the image area, the number of dots of transparent toner to place on the edge of the image area, and use of the transparent toner. adjust any of the ranges,
The image forming apparatus according to (14) or (15), characterized in that:

(17) The transparent toner processing section includes:
When printing on both sides of the recording medium, depending on double-sided printing, whether or not the transparent toner is placed on the edge of the image area, the number of dots of the transparent toner placed on the edge of the image area, and/or the transparent toner Adjust the usage range of
The image forming apparatus according to any one of (14) to (16).

(18) an image forming section that forms a transparent toner image on a recording medium;
a transparent toner processing unit that performs processing to place transparent toner on an edge portion of an image area of the toner image on the recording medium;
A transparent toner processing method performed by a transparent toner processing device comprising:
a step in which the transparent toner processing unit selects an edge portion between the image area and the non-image area as an area on which transparent toner is to be placed;
reducing the number of dots on the edge of the area where the transparent toner is placed compared to other areas;
A transparent toner processing method characterized by carrying out.

(19) an image forming section that forms a transparent toner image on a recording medium;
a transparent toner processing unit that performs processing to place transparent toner on an edge portion of an image area of the toner image on the recording medium;
A transparent toner processing device equipped with
a step of selecting an edge portion between the image area and the non-image area as an area on which transparent toner is to be placed;
a step of reducing the number of dots at the edge of the area on which the transparent toner is placed and the non-image area compared to other areas;
A transparent toner processing program characterized by executing the following.

According to the present invention, it is possible to blur the gloss of the edge portion to make the difference in gloss less noticeable.

1 is a diagram schematically showing the overall configuration of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a functional block diagram showing an example of a hardware configuration of an image forming apparatus. FIG. 2 is a partially enlarged view showing a recording medium in which a transparent toner processing section randomly places transparent toner on edge portions of line image and/or solid image areas on printing paper; FIG. 2 is a partially enlarged view showing a recording medium in which a transparent toner processing section has applied transparent toner in a sawtooth pattern to the edge portion of a line image and/or solid image area on a printing paper. FIG. 2 is a partially enlarged view showing a recording medium in which a transparent toner processing unit has applied transparent toner in a mountain-like pattern to the edge portion of a line image and/or solid image area on a printing paper; FIG. 2 is an explanatory diagram showing a recording medium on which transparent toner is placed on the edge portion of a one-dot image. FIG. 2 is an explanatory diagram showing a recording medium on which transparent toner is placed on the edge portion of a 4-dot image. FIG. 2 is an explanatory diagram showing a recording medium on which transparent toner is placed on the edge portion of a 9-dot image. FIG. 2 is an explanatory diagram showing a recording medium on which transparent toner is placed on the edge portion of a 16-dot image. FIG. 4 is an explanatory diagram illustrating the number of dots of transparent toner arranged in a predetermined area of the dot images of FIGS. 4A to 4D. FIG. 3 is an explanatory diagram showing a recording medium on which a transparent toner processing section has placed transparent toner on the edge portion of a 25-dot image. FIG. 3 is an explanatory diagram showing a recording medium on which a transparent toner processing section has placed transparent toner on the edge portion of a 36-dot image. FIG. 3 is an explanatory diagram showing a recording medium on which a transparent toner processing section has placed transparent toner on the edge portion of a 49-dot image. FIG. 3 is an explanatory diagram showing a recording medium on which a transparent toner processing section has placed transparent toner on the edge portion of a 64-dot image. FIG. 3 is an explanatory diagram showing a recording medium on which a transparent toner processing section has placed transparent toner on the edge portion of an 81-dot image. FIG. 3 is an explanatory diagram showing a recording medium on which a transparent toner processing section has placed transparent toner on the edge portion of a 100-dot image. FIG. 3 is an explanatory diagram illustrating the number of dots of transparent toner to be placed on an area around a predetermined size of a dot image. FIG. 3 is an explanatory diagram showing a recording medium on which a transparent toner processing section carries transparent toner when the gloss of the transparent toner is higher than that of the toner (line image, solid image). FIG. 3 is an explanatory diagram showing a recording medium on which a transparent toner processing section carries transparent toner when the gloss of the transparent toner is higher than the gloss of the toner (dot image). FIG. 7 is an explanatory diagram illustrating a recording medium on which transparent toner is placed through correction processing by a transparent toner processing unit when the gloss of the transparent toner is higher than the gloss of the toner (line image, solid image). FIG. 3 is an explanatory diagram (dot image) showing a recording medium on which transparent toner is placed through correction processing by a transparent toner processing unit when the gloss of the transparent toner is higher than the gloss of the toner. 3 is a flowchart showing the basic operation of the image forming apparatus according to the present embodiment. 7 is a flowchart showing the operation of the image forming apparatus according to the present embodiment when there is a difference in gloss.

Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the respective figures.
FIG. 1 is a diagram schematically showing the overall configuration of an image forming apparatus 1 according to an embodiment of the present invention. FIG. 2 is a functional block diagram showing an example of the hardware configuration of the image forming apparatus 1. As shown in FIG. The configuration of the image forming apparatus 1 will be explained using FIGS. 1 and 2.

Although the present embodiment will be described using the image forming apparatus 1, the present invention is not limited to the image forming apparatus 1. For example, a transparent toner processing apparatus without an image forming unit, which will be described later as a modified example, may be used. .

The image forming apparatus 1 employs an intermediate transfer method using electrophotographic process technology. In the image forming apparatus 1, the image forming unit 20T primarily transfers the transparent toner image formed on the photoreceptor drum 23T onto the intermediate transfer belt 26, and then the image forming units 20Y, 20M, 20C, and 20K transfer the transparent toner image to each photoreceptor drum 23T. The toner images of Y (yellow), M (magenta), C (cyan), and K (black) formed on 23Y, 23M, 23C, and 23C are primarily transferred to the intermediate transfer belt 26.

The photoreceptor drum 23T corresponding to transparent toner and the photoreceptor drums 23Y, 23M, 23C, and 23C corresponding to the four colors of YMCK are arranged along the moving direction of the intermediate transfer belt 26. The image forming apparatus 1 employs a tandem system in which a transparent toner image and each color toner image are sequentially transferred to the intermediate transfer belt 26.

Image forming unit 20T is arranged upstream of image forming units 20Y, 20M, 20C, and 20K. Therefore, the image forming unit 20T first primarily transfers the transparent toner image formed on the photoreceptor drum 23T onto the intermediate transfer belt 26. Thereafter, on the transparent toner image placed on the intermediate transfer belt 26 by the image forming unit 20T, Y (yellow), M (magenta), and C ( The toner images of each color (cyan) and K (black) are primarily transferred. The image forming device 1 forms a transparent toner image and a toner image by overlapping a transparent toner image and four-color toner images on an intermediate transfer belt 26 and then performing secondary transfer onto printing paper (recording medium). .

As shown in FIG. 2, the image forming apparatus 1 mainly includes an image reading section 11, an operation display section 12, an image processing section 13, a transparent toner processing section 131, an image forming section 14, a transport section 15, and a control section 10. Equipped with etc.

The control unit 10 includes a CPU (Central Processing Unit) 101, a ROM (Read Only Memory) 102, a RAM (Random Access Memory) 103, and the like. The CPU 101 reads a program 161 according to the processing content from the storage unit 16, expands it to the RAM 103, executes the expanded program 161, embodies the image processing unit 13 and the transparent toner processing unit 131, and further implements the image processing unit 13 and the transparent toner processing unit 131. control each component of the At this time, various data stored in the storage unit 16 are referred to. The storage unit 16 includes, for example, a nonvolatile semiconductor memory (so-called flash memory) or a hard disk drive.

The control unit 10 transmits and receives various data to and from an external device (for example, a personal computer) connected to a communication network such as a LAN (Local Area Network) or a WAN (Wide Area Network) via the communication unit 17. conduct. For example, the control unit 10 receives image data transmitted from an external device, and forms a toner image on printing paper based on this image data (input image data). The communication unit 17 is composed of a communication control card such as a LAN card, for example.

The image forming section 14 includes a fixing device 5, an intermediate transfer unit 19, and image forming units 20T, 20Y, 20M, 20C, and 20K. The image forming unit 14 of this embodiment forms an image area of a toner image and a transparent toner image placed on the edge portion of the image area on printing paper (recording medium) based on image data.

The conveyance section 15 includes all rollers such as conveyance rollers 32 and 33 shown in FIG. The control unit 10 controls the conveyance of the paper along the conveyance path by driving the conveyance unit 15 .

The control unit 10 controls each component included in the image forming apparatus 1. The control unit 10 may also be called a control device or a controller.

The image reading unit 11 is, for example, a line sensor, and is installed downstream of the fixing device 5. The image reading unit 11 detects the difference in gloss between the transparent toner and the toner in the toner area by reading the transparent toner and the toner area (image area) formed on the printing paper.

The operation display unit 12 includes, for example, a liquid crystal display (LCD) with a touch panel. The operation display section 12 includes a display section 121 and an operation section 122. The display unit 121 displays various operation screens, image status display, operating status of each function, etc. under the control of the control unit 10. The operation unit 122 includes various operation keys such as a numeric keypad and a start key. The operation unit 122 receives various input operations by the user and outputs operation signals to the control unit 10.

The image processing unit 13 detects edges of input image data input from the outside. Then, the image processing unit 13 performs tone correction based on tone correction data (for example, tone correction table LUT) in the storage unit 16. The image processing unit 13 performs various correction processes such as color correction and shading correction, compression processing, etc. in addition to gradation correction on input image data. Based on the image data subjected to these processes, the image forming section 14 forms a toner image on printing paper.

The transparent toner processing unit 131 performs processing for placing transparent toner on the edge portion of the image area of the toner image formed on the recording medium. The transparent toner processing section 131 places the transparent toner on the printing paper by the image forming section 14 starting from the edge of the image area, and the number of dots at the edge of the transparent toner area and the non-image area is as follows. It has been reduced compared to other areas. This makes it possible to blur the gloss level difference at the edge portion of the image area and to blur the gloss level at the edge portion between the transparent toner area and the non-image area, thereby making the gloss level difference less noticeable.

Media sensors 18A, 18B, and 18C determine the type of printing paper. Each of the media sensors 18A, 18B, and 18C is attached to each of the paper feed tray units 31a to 31c, and measures the glossiness and paper size of the printing paper placed on the paper feed tray units 31a to 31c, and detects the printing paper. Determine the type of. Note that instead of the media sensors 18A, 18B, and 18C, one media sensor may be provided on the conveyance path to determine the type of printing paper being conveyed. Note that what is placed on each paper feed tray unit 31a to 31c is not limited to printing paper, and may be any recording medium such as an OHP (OverHead Projector) sheet.

Returning to FIG. 1, the explanation will be continued. The image forming section 14 includes an image forming unit 20T, image forming units 20Y, 20M, 20C, and 20K shown in FIG. 2, an intermediate transfer unit 19, and a fixing device 5. The image forming section 14 forms and fixes a toner image on printing paper.

The image forming unit 20T transfers transparent toner to the edge portion of the image area based on the input image data. The image forming units 20Y, 20M, 20C, and 20K perform transfer using colored toners of a yellow component, a magenta component, a cyan component, and a black component based on input image data. The image forming unit 20Y for the yellow component, the image forming unit 20M for the magenta component, the image forming unit 20C for the cyan component, and the image forming unit 20K for the black component have similar configurations.

In the following description, the constituent elements of the image forming unit 20Y for the yellow component will be explained, and the explanation of the constituent elements of the other similarly configured image forming units 20M, 20C, 20K, and 20T will be omitted.

The image forming unit 20Y includes an exposure device 21Y, a developing device 22Y, a photosensitive drum 23Y, a charging device 24Y, a drum cleaning device 25Y, and the like. This image forming unit 20Y forms a yellow component toner image on the intermediate transfer belt 26.

The photosensitive drum 23Y includes, for example, an under coat layer (UCL), a charge generation layer (CGL), and a charge transport layer on the circumferential surface of a conductive cylinder made of aluminum (for example, an aluminum tube). It is a negatively charged organic photoconductor (OPC) in which layers (CTL: Charge Transport Layer) are sequentially laminated. The charge generation layer is made of an organic semiconductor in which a charge generation material (eg, phthalocyanine pigment) is dispersed in a resin binder (eg, polycarbonate). The charge generation layer generates a pair of positive charges and negative charges by exposure by the exposure device 21Y. The charge transport layer is made of a hole transport material (electron-donating nitrogen-containing compound) dispersed in a resin binder (for example, polycarbonate resin), and transports the positive charges generated in the charge generation layer to the surface of the charge transport layer. do.

The control unit 10 rotates the photoreceptor drum 23Y at a constant circumferential speed by supplying a drive current to a drive motor (not shown) for the photoreceptor drum 23Y.

The charging device 24Y uniformly charges the surface of the photoconductive drum 23Y to a negative polarity. The exposure device 21Y is composed of, for example, a semiconductor laser, and irradiates the photoreceptor drum 23Y with a laser beam corresponding to an image of a yellow color component. Positive charges are generated in the charge generation layer of the photoreceptor drum 23Y and transported to the surface of the charge transport layer, thereby neutralizing the surface charges (negative charges) of the photoreceptor drum 23Y. An electrostatic latent image of a yellow color component is formed on the surface of the photoreceptor drum 23Y due to the potential difference with the surroundings.

The developing device 22Y is, for example, a two-component developing type developing device. The developing device 22Y forms a toner image by attaching toner of a yellow color component to the surface of the photoreceptor drum 23Y. A toner image is formed by visualizing an electrostatic latent image.

The drum cleaning device 25Y includes a drum cleaning blade and the like as a cleaning member that comes into sliding contact with the surface of the photoreceptor drum 23Y. The drum cleaning device 25Y uses a drum cleaning blade to remove toner remaining on the surface of the photoreceptor drum 23Y after the primary transfer.

Similarly, the image forming unit 20M includes an exposure device 21M, a developing device 22M, a photosensitive drum 23M, a charging device 24M, a drum cleaning device 25M, and the like. The image forming unit 20C includes an exposure device 21C, a developing device 22C, a photosensitive drum 23C, a charging device 24C, a drum cleaning device 25C, and the like. The image forming unit 20K includes an exposure device 21K, a developing device 22K, a photosensitive drum 23K, a charging device 24K, a drum cleaning device 25K, and the like. The image forming unit 20T includes an exposure device 21T, a developing device 22T, a photosensitive drum 23T, a charging device 24T, a drum cleaning device 25T, and the like.

The image forming unit 20T transfers the transparent toner image to the intermediate transfer belt 26 at the most upstream position, and then the image forming units 20Y, 20M, 20C, and 20K sequentially transfer the toner images to the intermediate transfer belt. A toner image is formed on the output printing paper, and transparent toner is placed on the edge portion of the image area of this toner image. In this case, on the printing paper on which the image forming unit 20T has placed the transparent toner, the transparent toner is placed from the edge of the toner area (image area), and the number of dots at the edge between the transparent toner area and the non-image area is It has been reduced compared to other areas. The image forming unit 20T uses transparent toner instead of colored toner. Note that details of the processing of the transparent toner processing section 131 that controls the image forming unit 20T will be explained using FIGS. 3A to 11, which will be described later.

The intermediate transfer unit 19 includes an intermediate transfer belt 26, primary transfer rollers 231T, 231Y, 231M, 231C, and 231K, a backup roller 27, a plurality of support rollers 29, a drive roller 28, and a secondary transfer roller 34. Be prepared. This intermediate transfer unit 19 forms a transparent toner image and a toner image on the intermediate transfer belt 26, and transfers the formed transparent toner image and toner image onto printing paper.

The intermediate transfer belt 26 is composed of an endless belt. The intermediate transfer belt 26 is stretched in a loop around a plurality of support rollers 29, a backup roller 27, a drive roller 28, and primary transfer rollers 231T, 231Y, 231M, 231C, and 231K. The plurality of support rollers 29 are composed of driven rollers. The drive roller 28 is preferably arranged, for example, on the downstream side in the belt running direction than the primary transfer roller 231K for the black component. This makes it easier to maintain a constant running speed of the belt in the primary transfer section. As the drive roller 28 rotates, the intermediate transfer belt 26 travels in the direction of arrow A at a constant speed.

The primary transfer roller 231T is arranged on the inner peripheral surface side of the intermediate transfer belt 26, facing the photosensitive drum 23T. The intermediate transfer belt 26 is sandwiched between the primary transfer roller 231T and the photosensitive drum 23T. A primary transfer nip is formed by the primary transfer roller 231T coming into pressure contact with the photoreceptor drum 23T. The primary transfer nip transfers the transparent toner image from the photosensitive drum 23T to the intermediate transfer belt 26.

The primary transfer roller 231Y is arranged on the inner peripheral surface side of the intermediate transfer belt 26, facing the photosensitive drum 23Y. The intermediate transfer belt 26 is sandwiched between the primary transfer roller 231Y and the photosensitive drum 23Y. A primary transfer nip is formed by the primary transfer roller 231Y coming into pressure contact with the photoreceptor drum 23Y. The primary transfer nip transfers the toner image from the photosensitive drum 23Y to the intermediate transfer belt 26. Similarly, the primary transfer rollers 231M, 231C, and 231K are arranged on the inner peripheral surface side of the intermediate transfer belt 26, facing the photosensitive drums 23M, 23C, and 23K of each color component, and similarly, toner images are transferred to the intermediate transfer belt 26. transcribe.

The secondary transfer roller 34 is arranged on the outer peripheral surface side of the intermediate transfer belt 26, facing the backup roller 27. The backup roller 27 is arranged downstream of the drive roller 28 in the belt running direction. The intermediate transfer belt 26 is sandwiched between the secondary transfer roller 34 and the backup roller 27. Furthermore, the secondary transfer roller 34 is pressed against the backup roller 27, thereby forming a secondary transfer nip. The secondary transfer nip transfers the toner image from the intermediate transfer belt 26 to the printing paper.

The transparent toner image formed on the transparent toner photoreceptor drum 23T and the toner images formed on the photoreceptor drums 23Y, 23M, 23C, and 23K of each color are sequentially superimposed and primarily transferred onto the intermediate transfer belt 26. . Specifically, by applying a primary transfer bias to the primary transfer roller 231Y and applying an electric charge of opposite polarity to the toner to the back side of the intermediate transfer belt 26 (the side that contacts the primary transfer roller 231Y), the yellow component is The toner image is electrostatically transferred to intermediate transfer belt 26. A transparent toner image and toner images of each color are also transferred in the same manner.

Thereafter, when the printing paper passes through the secondary transfer nip, the transparent toner image and toner image on the intermediate transfer belt 26 are secondarily transferred to the printing paper. Typically, by applying a secondary transfer bias to the secondary transfer roller 34 and applying transparent toner and an electric charge of opposite polarity to the toner to the back side of the printing paper (the side that comes into contact with the secondary transfer roller 34). , the transparent toner image and the toner image are electrostatically transferred to the printing paper. The transparent toner image and the printing paper onto which the toner image has been transferred are conveyed toward the fixing device 5 .

The fixing device 5 is disposed on the downstream side of the secondary transfer nip, and includes an upper fixing device 51, a lower fixing device 52, a heat source (not shown), and the like. The upper fixing device 51 has a fixing surface side member disposed on the fixing surface side of the printing paper (the surface on which the transparent toner image and the toner image are formed). The lower fixing device 52 has a back side support member disposed on the back side (the side opposite to the fixing surface) of the printing paper. The fixing side member and the back side supporting member form a fixing nip.

The fixing nip pinches and conveys the printing paper. The fixing device 5 fixes the transparent toner image and the toner image onto the printing paper by heating and pressurizing the printing paper to which the transparent toner image and the toner image have been secondarily transferred in a fixing nip. Further, the fixing device 5 is provided with an air separation unit that separates the printing paper from the fixing surface side member by blowing air.

An image reading section 11 is provided downstream of the fixing device 5 and reads the transparent toner and toner area (image area) on the printing paper. Thereby, the difference in gloss between the transparent toner and the toner in the toner area is detected.

The transport section 15 includes a paper feed section, a paper discharge section, and a transport path. The three paper feed tray units 31a to 31c constituting the paper feed section are loaded with printing paper (for example, standard long sheets, A4 paper, etc.) that are identified based on basis weight, size, etc., according to preset types. be accommodated in.

The conveyance path includes a plurality of conveyance rollers, paper feed conveyance paths 41 to 44, conveyance paths 45 and 46, and a reversal conveyance path for forming images on both sides of the printing paper. The plurality of conveyance rollers include a pair of conveyance rollers 32 and 33, a roller 38, a discharge roller 35, conveyance rollers 36 and 37, and the like. A pair of conveyance rollers refers to two conveyance rollers facing each other. Conveyance rollers 32 and 33 and roller 38 are provided upstream of the secondary transfer nip.

The printing paper stored in the paper feed tray units 31a to 31c is fed out one by one from the top, and is transported to the image forming section 14 through paper feed transport paths 41 to 44 and the like. The roller 38 corrects the inclination of the printing paper and adjusts the timing of conveyance of the printing paper. The paper feed conveyance path 44 is a path for conveying printing paper fed from the paper feed tray units 31a to 31c to conveyance paths 45 and 46. The paper feed conveyance path 44 is connected to one end of the conveyance paths 45 and 46.

The paper feed conveyance paths 41 to 44 are provided near one side of the apparatus main body. The paper feed conveyance paths 41 to 44 are provided in the vertical (substantially vertical) direction from the paper feed tray units 31a to 31c to the conveyance path 45. A portion of the paper feed transport paths 41 to 44 is exposed to the outside when an opening/closing door (not shown) provided on one side of the apparatus body is opened. be done. As a result, a portion of the paper feed conveyance paths 41 to 44 is exposed to the outside, allowing the user to perform jam removal and the like.

The upper ends of the paper feed conveyance paths 41 to 44 are connected to the conveyance path 45, and the lower ends thereof are connected to the paper feed tray units 31a to 31c.

Next, the conveyance paths 45 and 46 will be explained. The conveyance paths 45 and 46 are paths for conveying the printing paper to the secondary transfer nip. In other words, the conveyance paths 45 and 46 are paths for conveying printing paper to the image forming section 14. Conveyance paths 45 and 46 are main conveyance paths along which printing paper is conveyed. This main conveyance path is a path for conveying printing paper from the upstream side in the conveyance direction via conveyance rollers 33, rollers 38, a secondary transfer nip, and a fixing nip. The conveyance path 46 is connected to a reversal conveyance path that reverses the printing paper.

The transport paths 45 and 46 are provided inside the apparatus above the paper feed tray units 31a to 31c, and extend from one side of the apparatus main body to the other side. Further, the other ends of the conveyance paths 45 and 46 are connected to a discharge port of a paper discharge section provided on the other side of the apparatus main body.

The secondary transfer nip transfers the transparent toner image and the toner image on the intermediate transfer belt 26 to one side (for example, the front surface) of the printing paper all at once. The fixing nip fixes the transferred transparent toner image and toner image. Note that in this embodiment, the image forming process includes a process of transferring onto a printing paper using a secondary transfer nip, and a process of fixing a transparent toner image and a toner image using a fixing nip. The printing paper on which the image has been formed is discharged to the outside of the machine by a paper discharge roller 35.

The reverse conveyance path is provided inside the apparatus main body between the paper feed tray units 31a to 31c and the main conveyance path. The reversing conveyance path extends from the other side to the one side of the apparatus main body. The reversal conveyance path includes a first reflux conveyance path 47 , a second reflux conveyance path 49 , and a storage path 48 . The first reflux conveyance path 47 branches downward from the conveyance path 46 on the downstream side of the fixing device in the conveyance direction of the sheet conveyed by the conveyance path 46 . The second circulation conveyance path 49 joins the conveyance path 46 on the upstream side of the secondary transfer nip.

Next, a case will be described in which double-sided printing is performed on printing paper fed from the paper feed tray units 31a to 31c. In the following, when double-sided printing is performed on printing paper, the side on which an image is formed first is referred to as the first side (or also referred to as the front side), and the side on which an image is formed after the image is formed on the first side. is called the second side (or also called the back side).

The control unit 10 causes the printing paper to be conveyed within the conveyance path 46 in the direction toward the secondary transfer nip. The secondary transfer nip transfers the image to the first side of the printing paper, and the fusing nip fixes the transferred image. The printing paper is conveyed by the control unit 10 so as to be conveyed from the conveyance path 46 via the first recirculation conveyance path 47 to the reverse conveyance path.

The printing paper (recording medium) is transported within the second circulation transport path 49 and the printing paper is turned over, so that the first side is on the bottom side and the second side is on the top side. The printing paper is conveyed to the upstream side of the secondary transfer nip with the second side of the printing paper facing upward. The secondary transfer nip transfers the image to the second surface on which no image is formed. A fusing nip then fuses this transferred image.

Next, the transparent toner processed by the transparent toner processing section 131 in the image forming apparatus 1 of this embodiment will be described. 3A to 3C show a processing method for the transparent toner processing section 131 to apply transparent toner by the image forming unit 20T according to the image.

3A to 3C show the recording medium 6 on which the transparent toner processing section 131 has placed transparent toner on the edge portion of the line image and/or solid image area on the printing paper using the image forming unit 20T. This is a partially enlarged view.

As shown in FIGS. 3A to 3C, the image area 70 formed on the recording medium 6 is a row of two dots from the left side, and is, for example, a partial area of a solid image. Transparent toner is placed on transparent toner areas 80 to 82 of five dots from the edge of the image area 70. The row of one dot on the right side is a non-image area 90 on which no toner or transparent toner is placed.

In FIG. 3A, each dot of transparent toner placed on the transparent toner area 80 of the recording medium 6 is shown. The number of transparent toner dots placed on the transparent toner area 80, which is the edge of the image area 70, decreases toward the non-image area 90, and the number of transparent toner dots decreases toward the image area 70. is increasing. In this way, the number of dots at the edges of the transparent toner area 80 and the non-image area 90 is smaller than the number of dots in the other transparent toner areas 80.

Further, in the present embodiment, the transparent toner processing section 131 determines that the edges of the transparent toner area 80 and the non-image area 90 on the recording medium 6 on which the transparent toner is placed by the image forming unit 20T are area scale. It is blurred by the tone. Note that area gradation refers to setting a matrix containing a plurality of dots, and changing the density stepwise in this matrix depending on the number of dots on which transparent toner is placed.

This makes it possible to blur the gloss at the edges of the transparent toner area 80 and the non-image area 90 to make the difference in gloss less noticeable, and also to make the difference in gloss at the edge between the image area 70 and the non-image area 90 less noticeable. can do.

In FIG. 3A, the recording medium 6 on which the transparent toner processing section 131 places the transparent toner by the image forming unit 20T is blurred by area gradation in a random pattern according to the distance from the non-image area 90 to each matrix. ing. The present embodiment is not limited to this, and for example, blurring may be performed using a predetermined pattern of area gradation depending on the distance from the non-image area 90 to each matrix.

FIG. 3B is a diagram showing the recording medium 6 on which transparent toner is deposited in a sawtooth pattern in the transparent toner area 81 in rows of five dots. Further, FIG. 3C is a diagram showing the recording medium 6 on which the transparent toner processing unit 20 has placed transparent toner in a mountain-like repeating pattern in the transparent toner area 82 in a row of five dots.

As shown in FIG. 3B, the recording medium 6 on which the transparent toner processing section 131 places the transparent toner by the image forming unit 20T may be blurred by area gradation in a sawtooth pattern. Further, as shown in FIG. 3C, the recording medium 6 on which the transparent toner processing section 131 has placed the transparent toner by the image forming unit 20T may be blurred by area gradation of a mountain-like repeating pattern. Furthermore, although the transparent toner areas 80 to 82 are columns of five dots, they are not limited to this, and may be rows of a predetermined number of dots. Furthermore, the transparent toner areas 80 to 82 may be arranged in rows of 3 dots or 8 dots.

4A to 4D are explanatory diagrams showing a recording medium 6 on which transparent toner is placed on the edge portions of dot images. FIG. 5 is an explanatory diagram illustrating the number of transparent toner dots arranged in predetermined areas of the dot images of FIGS. 4A to 4D. Each row in FIG. 5 shows the number of dots in the dot image, and each column shows the relationship between the distance from the dot image and the number of transparent toner dots.

The recording medium 6 on which the transparent toner is placed by the image forming unit 20T is processed by the transparent toner processing section 131 so that the edge portion of the dot image area on the printing paper corresponds to the edge portion of the line image and/or solid image area. The transparent toner is applied in a manner different from that shown in the figure. As an example, transparent toner areas 83 to 86 in which transparent toner is placed around the edges of a dot image will be described.

As shown in FIGS. 4A to 4D, transparent toner areas 83 to 86 on which transparent toner is placed are arranged around image areas 71 to 74 of dot images formed on the recording medium 6. In the transparent toner areas 83 to 86, the number of transparent toner dots decreases as the distance from the edges of the image areas 71 to 74 of the dot images increases. In each of FIGS. 4A to 4D, a predetermined range from the edge of the image areas 71 to 74 of the dot image is transparent toner areas 83 to 86 on which transparent toner is placed, and the area of the line image and/or solid image is The transparent toner is placed in a manner different from that on the edge portion.

Referring to FIG. 5, for example, in the case of the image area 71 of the 1-dot image shown in FIG. It is being In the transparent toner area 83, eight dots of transparent toner are placed at a distance of one dot from the edge portion. In addition, in the transparent toner area 83, 6 dots of transparent toner are placed at a distance of 2 dots from the edge portion, 4 dots of transparent toner are placed at a distance of 3 dots from the edge portion, and 4 dots of transparent toner are placed at a distance of 4 dots from the edge portion. 2 dots of transparent toner are placed on it.

Further, in the case of the image area 72 of the 4-dot image shown in FIG. 4B, transparent toner is placed radially in a transparent toner area 84 of 4 dots horizontally by 3 dots vertically from the edge of the image area 72. In the transparent toner area 84, 12 dots of transparent toner are placed at a distance of 1 dot from the edge portion, and 8 dots of transparent toner are placed at a distance of 2 dots from the edge portion. Furthermore, in the transparent toner area 84, 4 dots of transparent toner are placed at a distance of 3 dots from the edge portion, and 2 dots of transparent toner are placed at a distance of 4 dots from the edge portion.

Further, in the case of the image area 73 of the 9-dot image shown in FIG. 4C, transparent toner is placed radially in a transparent toner area 85 of 4 dots horizontally by 4 dots vertically from the edge of the image area 73. In the transparent toner area 85, 16 dots of transparent toner are placed at a distance of 1 dot from the edge portion, and 12 dots of transparent toner are placed at a distance of 2 dots from the edge portion. Further, in the transparent toner area 85, 8 dots of transparent toner are placed at a distance of 3 dots from the edge portion, and 4 dots of transparent toner are placed at a distance of 4 dots from the edge portion.

Further, in the case of the image area 74 of the 16-dot image shown in FIG. 4D, transparent toner is placed radially in a transparent toner area 86 of 4 dots horizontally by 4 dots vertically from the edge of the image area 74. In the transparent toner area 86, 20 dots of transparent toner are placed at a distance of 1 dot from the edge portion, and 16 dots of transparent toner are placed at a distance of 2 dots from the edge portion. Furthermore, in the transparent toner area 86, 8 dots of transparent toner are placed at a distance of 3 dots from the edge portion, and 4 dots of transparent toner are placed at a distance of 4 dots from the edge portion.

As shown in FIGS. 4A to 4D, transparent toner areas 83 to 86 are arranged around the image areas 71 to 74 of the dot image, and the number of transparent toner dots decreases as the distance from the edge of the dot image increases. ing. This makes it possible to blur the gloss of the edge portion of the dot image and make the difference in gloss less noticeable.

As a result, the transparent toner processing section 131 processes the transparent toner areas 83 to 86 and the edge portions of the non-image area around them, even in the case of a dot image, on the recording medium 6 on which the transparent toner is placed by the image forming unit 20T. Since the gloss is blurred, the gloss level difference can be made less noticeable, and at the same time, the gloss level difference at the edge portions between the image areas 71 to 74 and the non-image area can be made less noticeable.

6A to 6F show a recording medium in which the transparent toner processing section 131 places transparent toner in transparent toner areas 87 to 89 on the edge portions of image areas 75 to 78, 170, and 171 of dot images using the image forming unit 20T. FIG. 6 is an explanatory diagram showing 6. FIG. 7 is an explanatory diagram illustrating the number of dots of transparent toner to be placed on the transparent toner areas 87 to 89 around the image areas 75 to 78, 170, and 171 of the dot image.

On the recording medium 6 on which the transparent toner has been placed by the image forming unit 20T, the transparent toner processing section 131 determines which area to place the transparent toner on based on the size of the dots in the image areas 75 to 78, 170, and 171 on the printing paper. Certain clear toner areas 87-89 have been modified. 6A to 6F, an example will be described in which the predetermined size of the dot image is, for example, 9 dots vertically by 9 dots horizontally or 10 dots vertically by 10 dots horizontally.

As shown in FIGS. 6A to 6F, on the recording medium 6, transparent toner is placed on transparent toner areas 87 to 89 arranged at the edge portions of the image area by the image forming unit 20T.

Referring to FIG. 7, for example, in the case of the image area 75 of the 25-dot (vertical 5 dots x horizontal 5 dots) image shown in FIG. 24 dots of transparent toner are placed at a distance of . Further, in the transparent toner area 87, 12 dots of transparent toner are placed at a distance of 2 dots from the edge portion. Neither toner nor transparent toner is placed on the other edge areas.

In addition, in the case of the image area 76 of the 36-dot (vertical 6 dots x horizontal 6 dots) image shown in FIG. Contains transparent toner. Further, in the transparent toner area 88, 16 dots of transparent toner are placed at a distance of 2 dots from the edge portion. Neither toner nor transparent toner is placed on the other edge regions.

In addition, in the case of the image area 77 of the 49-dot (7 dots vertically x 7 dots horizontally) image shown in FIG. Contains transparent toner. In addition, in the case of the image area 78 of the 64-dot (vertical 8 dots x horizontal 8 dots) dot image shown in FIG. Transparent toner is loaded.

As shown in FIGS. 6A to 6D, on the recording medium 6, transparent toner is placed in transparent toner areas 87 to 89, 188 at the edge portions of image areas 75 to 78 of the dot images. In the transparent toner areas 87 to 89, 188, the number of transparent toner dots is reduced as the distance from the edge portion of the image areas 75 to 78 of the dot image increases. As a result, even if the dot image is large, by placing transparent toner on the outside of the dot image, the gloss at the edge portion can be blurred and the difference in gloss level can be made less noticeable.

Further, the transparent toner processing unit 131 may not apply transparent toner if any of the dot size, line width, and solid patch size of the image area on the printing paper is equal to or larger than a threshold value.

For example, in the case of the image area 170 of the 81-dot (vertical 9 dots x horizontal 9 dots) image shown in FIG. 6E, and in the case of the image area 171 of the 100-dot (vertical 10 dots x horizontal dots) image shown in FIG. Media 6 shows that clear toner is not placed on the edge portion. For example, in a dot image of 81 dots or more, the dots themselves are large, so the gloss level difference is not noticeable in the halftone dot pattern made up of dots. Therefore, for example, the transparent toner processing unit 131 may be set to not perform the process of applying transparent toner by setting 81 dots as a threshold value. In other words, it is possible to set the transparent toner processing unit 131 not to treat a dot image of 81 dots or more as dots.

Further, when the thickness of the line width or the size of the solid patch is equal to or greater than a predetermined threshold value, the transparent toner processing unit 131 is set not to perform the process of applying transparent toner. Thereby, consumption of excess transparent toner by the image forming unit 20T can be suppressed.

The predetermined size of the dot image is, for example, 81 dots (9 dots vertically x 9 dots horizontally), but the predetermined size is not limited to this, and may be larger or smaller than this. It is not limited.

Further, in FIG. 7, the number of dots on which transparent toner is applied is partially different between 9 dots and 16 dots in FIG. 5, but this is an example and is not particularly limited.

Next, processing when there is a difference between the gloss of the transparent toner and the gloss of the toner will be described.
FIGS. 8A and 8B are explanatory diagrams showing the recording medium 6 on which the transparent toner processing section 131 has placed transparent toner by the image forming unit 20T when the gloss of the transparent toner is higher than the gloss of the toner. In this case, transparent toner is placed on the image areas 70 and 73 of the recording medium 6. Furthermore, in the transparent toner area 80 of the recording medium 6, the number and/or range of transparent toner dots is adjusted from the edges with the image areas 70 and 73 toward the edge with the non-image area 90.

When the gloss of the transparent toner is higher than the gloss of the toner, a difference in gloss occurs at the boundary between the transparent toner and the toner. For example, as shown in FIG. 8A, in the case of a line image or a solid image, in the image area 70, a transparent toner area 180 on which two rows of transparent toner are placed is placed from the edge of the image area 70 toward the center. It is provided. In this case, in the transparent toner area 180 of the recording medium 6, the number of transparent toner dots is gradually reduced from the edge portion of the image area 70 toward the center. As a result, the gloss at the edge portion of the image area 70 is blurred to make the difference in gloss less noticeable.

Further, as shown in FIG. 8B, in the case of the image area 73 of a dot image, a transparent toner area 181 on which transparent toner is placed is provided from the edge portion of the image area 73 toward the center. ing. In this case, on the recording medium 6 on which the transparent toner processing section 131 has applied transparent toner by the image forming unit 20T, the number of dots of transparent toner is reduced from the edge portion of the image area 73 toward the center. As a result, the gloss at the edge portion of the image area 73 is blurred to make the difference in gloss less noticeable.

Note that the difference in gloss between the gloss of the transparent toner and the gloss of the toner can be detected by reading the transparent toner printed on the recording medium and the toner using the image reading unit 11.

Further, the transparent toner processing unit 131 can adjust the number and/or range of transparent toner dots placed on the recording medium 6 from the non-image area to the image areas 70 and 73 on the recording medium 6. . In this case, on the recording medium 6, either the number or range of dots on which the transparent toner is placed is adjusted based on the difference in gloss between the transparent toner formed on the recording medium 6 and the toner in the image area.

9A and 9B are explanatory diagrams showing the recording medium 6 on which the transparent toner processing section 131 performs correction processing and the transparent toner is placed on by the image forming unit 20T when the gloss of the transparent toner is higher than the gloss of the toner. be. When the gloss of the transparent toner is higher than the gloss of the toner, a difference in gloss occurs at the boundary between the transparent toner and the toner.

For example, as shown in FIG. 9A, in the case of a line image or a solid image, three rows of transparent toner areas 182 are provided at the edge portion of the image area 70. In this case, the transparent toner area 182 is set narrower than the transparent toner area 80 shown in FIG.

Further, as shown in FIG. 9B, in the case of the image area 74 of the dot image, a transparent toner area 183 is provided at the edge portion of the image area 74, and the surrounding area is a non-image area. In this case, the transparent toner area 183 is set narrower than the transparent toner area 86 shown in FIG. 4D.

In addition, in this embodiment, the processing of 3 dots for line images and solid images, and 4 dots for dot images is an example, and is not limited to this, and the number of dots can be set to be larger or smaller as appropriate. You may.

(motion)
FIG. 10 is a flowchart showing the basic operation of the image forming apparatus 1 according to this embodiment. Note that FIG. 10 shows a control flow when there is no difference in gloss between the transparent toner and the toner.

As shown in FIG. 10, the image forming apparatus 1 acquires print image data in the transparent toner processing section 131 (step S001). The transparent toner processing unit 131 then processes each area of the print image data from steps S002 to S012.

The transparent toner processing unit 131 determines whether an edge is detected in this area based on the edge processing of the image data by the image processing unit 13 (step S003). For example, the transparent toner processing unit 131 performs edge detection every 5 dots in the main scanning direction, and when an edge is detected (Yes in step S003), the process proceeds to step S005 and determines whether the image area related to this edge is a dot. Determine whether or not.

On the other hand, if no edge is detected in this area (No in step S003), the transparent toner processing unit 131 does not execute the process for applying transparent toner (step S007), and proceeds to step S012.

In step S005, if the transparent toner processing unit 131 determines that the image area related to this edge is a dot (Yes in step S005), the process proceeds to step S009, and as illustrated in FIGS. 4A to 4D, the transparent toner processing unit 131 performs the detection Processing is performed to place transparent toner on the edge portions of the dot images (step S009). Thereafter, the transparent toner processing section 131 proceeds to step S012.

On the other hand, if it is determined that the image area related to this edge is not a dot (No in step S005), the transparent toner processing unit 131 proceeds to step S011, and applies transparent toner to the edge portion of the line image or solid image. Processing for loading is performed (step S011). Thereafter, the transparent toner processing section 131 proceeds to step S012.

That is, the transparent toner processing unit 131 adjusts whether to place transparent toner on the edge of the image area, the number of dots of transparent toner to be placed on the edge of the image area, and the size of the transparent toner area.

Then, if the transparent toner processing unit 131 has not processed any area of the print image data, the process returns to step S002. When the transparent toner processing unit 131 has executed all the processing for the print image data area, the process proceeds to step S013.

In step S013, the image forming unit 14 forms an image processed with transparent toner on printing paper, outputs this as a printed matter (step S013), and ends the process of FIG. 10.

Note that in FIG. 10, edge detection is performed every 5 dots in the main scanning direction, but this embodiment is merely an example and is not particularly limited to 5 dots. That is, the number of dots may be greater or less than 5 dots. Further, the transparent toner processing unit 131 may perform transparent toner processing on all printed images without detecting edges.

FIG. 11 is a flowchart showing the operation of the image forming apparatus 1 according to the present embodiment when there is a difference in gloss. The difference between the flowchart in FIG. 11 and the flowchart in FIG. 10 is that the difference in gloss between the transparent toner and the toner is detected, and if the detected difference in gloss is greater than a threshold, transparent toner is also placed on the image area. The point here is that the process is executed.

As shown in FIG. 11, the image forming apparatus 1 uses the image reading unit 11 to read an image already printed on printing paper by the image forming unit 14, and detects transparent toner and toner gloss from the printing paper (step S101). .

The transparent toner processing unit 131 calculates the gloss difference between the transparent toner and the toner (step S103). The transparent toner processing unit 131 acquires print image data (step S001). Then, the transparent toner processing unit 131 executes repeated processing regarding each area of the print image data from steps S002 to S012.
The transparent toner processing unit 131 determines whether the difference in gloss between the transparent toner and the toner in the image area is greater than or equal to a predetermined threshold (step S105).

If the difference in gloss between the transparent toner and the toner is greater than or equal to the predetermined threshold (Yes in step S105), the transparent toner processing unit 131 proceeds to step S107 and applies transparent toner to the image area as illustrated in FIG. 8A or 8B. Processing for loading is performed (step S107). The transparent toner processing unit 131 then proceeds to step S003 and executes the same process as that from step S003 in FIG. 10.

Note that in step S107, the transparent toner processing unit 131 performs processing for placing transparent toner on the image area, but the present embodiment is not limited to this. For example, the transparent toner processing unit 131 may correct the range in which the transparent toner is placed.

Specifically, if the gloss difference is equal to or greater than the threshold value, the transparent toner processing unit 131 may correct the number of dots on which transparent toner is placed from 5 dots to 3 dots in step S107.

As described above, the image forming apparatus 1 according to the present embodiment includes an image forming unit 20T that forms a transparent toner image on a recording medium, and a unit that places transparent toner on the edge portion of the image area of the toner image on printing paper. A transparent toner processing section 131 is provided for processing. The transparent toner processing section 131 prints the printing paper on which the transparent toner is placed by the image forming unit 20T, and the transparent toner is placed on the edge portion of the image area, and the dots on the edge portion between the transparent toner area and the non-image area. The number of dots is reduced compared to the number of dots in other areas.

This makes it possible to blur the gloss at the edges of the transparent toner area and the non-image area to make the difference in gloss less noticeable, and it is also possible to make the difference in gloss at the edges between the image area and the non-image area less noticeable. .

(Modified example)
The present invention is not limited to the above-described embodiments, and can be modified without departing from the spirit of the present invention. Examples include the following (a) to (g).

(a) In the present embodiment, the image forming apparatus 1 including the image forming section 14 of each color and the transparent toner processing section 131 has been described, but the present invention is not limited to this. For example, the image forming unit 20T It may be realized as a transparent toner processing device including a transparent toner processing section 131 and a transparent toner processing section 131. The transparent toner processing device can, for example, perform transparent toner processing on a printed recording medium to blur the gloss of the edge portion of the image area and make the gloss level difference less noticeable.

(b) The transparent toner processing unit 131 may switch whether or not to place the transparent toner on the edge of the image area, depending on the image attribute information indicating the print type, and the number of dots of the transparent toner to be placed on the edge of the image area. , and the usage range of the transparent toner may be adjusted. For example, characters, photographs, figures, etc. can be assigned as image attribute information. As a result, the transparent toner processing unit 131 can be set to not perform the process of applying transparent toner on a photograph, and can prevent deterioration of the image quality of the photograph due to the transparent toner. Further, for characters, the area on which transparent toner is placed can be relatively increased, and for graphics, the area on which transparent toner is placed can be relatively reduced, and deterioration in the image quality of graphics due to transparent toner can be suppressed. Further, the transparent toner processing section 131 may be configured to include a plurality of image forming units that form a plurality of transparent toner images, respectively, and to selectively use the plurality of transparent toners in the region on which the transparent toner is placed.

(c) The transparent toner processing unit 131 may switch whether or not to place the transparent toner on the edge of the image area according to the printing rate information of the toner image on the recording medium 6, and furthermore, the transparent toner processing unit 131 may switch whether or not to place the transparent toner on the edge of the image area. Either the number of toner dots or the usage range of transparent toner may be adjusted.

(d) The transparent toner processing unit 131 may switch whether or not to place the transparent toner on the edges of the image area based on the edge processing of the image data by the image processing unit 13. Either the number of dots or the size of the transparent toner area may be adjusted.
(e) The image forming unit 14 is not limited to forming a toner image made of four types of toner, but may form a toner image made of one or more types of toner on printing paper, for example.

(e) The transparent toner processing unit 131 may switch whether or not to place the transparent toner on the edge of the image area according to edge processing or the pattern of the image, and the number of dots of transparent toner to be placed on the edge of the image area. , and the usage range of the transparent toner may be adjusted. For example, depending on edge thinning or image processing, you can decide whether to place transparent toner on the edge of the image area, the number of dots of transparent toner to place on the edge of the image area, and the usage range of transparent toner. Can be adjusted.

(f) The transparent toner processing unit 131 includes media sensors 18A to 18C that determine the type of printing paper, and the transparent toner processing unit 131 applies transparent toner to the edges of the image area according to the glossiness of the printing paper determined by the media sensors 18A to 18C. The number of dots of transparent toner to be placed on the edge of the image area and the range of use of the transparent toner may be adjusted. Thereby, the amount of transparent toner to be used can be determined depending on the type of printing paper.

(g) When printing on both sides of printing paper, the transparent toner processing unit 131 may switch whether or not to place transparent toner on the edges of the image area depending on double-sided printing, The number of toner dots and/or the usage range of transparent toner may be adjusted. Thereby, for example, the gloss of the first side and the second side can be changed, and the amount of transparent toner used on the two sides can be reduced.

1 Image forming device (transparent toner processing device)
10 Control section 11 Image reading section 12 Operation display section 121 Display section 122 Operation section 13 Image processing section 14 Image forming section 15 Conveying section 16 Storage section 17 Communication section 19 Intermediate transfer unit 101 CPU
102 ROM
103 RAM
131 Transparent toner processing section 20Y, 20M, 20C, 20K, 20T Image forming unit (image forming section)
21Y, 21M, 21C, 21K, 21T Exposure device 22Y, 22M, 22C, 22K, 22T Developing device 23Y, 23M, 23C, 23K, 23T Photosensitive drum 231Y, 231M, 231C, 231K, 231T Primary transfer roller 24Y, 24M, 24C, 24K, 24T Charging devices 25Y, 25M, 25C, 25K, 25T Drum cleaning device 26 Intermediate transfer belt 27 Backup roller 28 Drive roller 29 Support rollers 31a to 31c Paper feed tray unit 34 Secondary transfer rollers 32, 33, 36, 37 Conveyance roller (conveyance section)
35 Paper discharge roller 38 Rollers 41 to 44 Paper feed conveyance paths 45, 46 Conveyance path 47 First return conveyance path 48 Accommodation path 49 Second return conveyance path 5 Fixing device 51 Upper fixing device 52 Lower fixing device 6 Recording medium

Claims (19)

an image forming section that forms a transparent toner image on a recording medium;
a transparent toner processing unit that performs processing to place transparent toner on an edge portion of an image area of the toner image on the recording medium;
Equipped with
In the recording medium on which the image forming section has placed transparent toner, the transparent toner is placed from the edge portion of the image area, and the number of dots at the edge of the transparent toner area and the non-image area is reduced compared to other areas. has been,
A transparent toner processing device characterized by: The recording medium on which the image forming section has placed transparent toner has edges between the transparent toner area and the non-image area on the recording medium being blurred by area gradation.
The transparent toner processing device according to claim 1, characterized in that: The recording medium on which the image forming section has placed transparent toner has transparent toner placed on edge portions of line image and/or solid image areas on the recording medium.
The transparent toner processing device according to claim 1 or 2, characterized in that: The recording medium on which the image forming section has placed the transparent toner is configured to apply the transparent toner to the edge portion of the dot image area on the recording medium in a manner different from that to the edge portion of the line image and/or solid image area. is listed,
The transparent toner processing device according to any one of claims 1 to 3. The recording medium on which the image forming section has placed transparent toner has transparent toner also placed on the image area on the recording medium.
The transparent toner processing device according to any one of claims 1 to 4. The recording medium on which the image forming section has placed the transparent toner has a dot number and/or range of the transparent toner adjusted from the non-image area to the image area on the recording medium.
The transparent toner processing device according to claim 5, characterized in that: The recording medium on which the image forming section has placed transparent toner has transparent toner placed in a predetermined range from the edge of the image area on the recording medium toward the non-image area.
The transparent toner processing device according to any one of claims 1 to 6. The recording medium on which the transparent toner is placed by the image forming section has an area on which the transparent toner is placed changed based on the size of a dot in the image area on the recording medium.
The transparent toner processing device according to claim 4, characterized in that: The recording medium on which the image forming section has placed the transparent toner, if any of the dot size, line width thickness, and solid patch size of the image area on the recording medium is equal to or larger than a threshold value, Clear toner is not loaded.
The transparent toner processing device according to claim 8, characterized in that: The recording medium on which the transparent toner is placed by the image forming section is determined based on the gloss difference between the transparent toner on the recording medium and the toner in the image area, and the number and range of dots on which the transparent toner is placed. has been adjusted,
The transparent toner processing device according to any one of claims 1 to 9. comprising an image reading unit that reads the transparent toner formed on the recording medium and the toner in the image area and detects a difference in gloss between the transparent toner and the toner in the image area;
The transparent toner processing device according to claim 10. The image forming section determines whether or not the transparent toner is placed on the edge of the image area, and whether or not the transparent toner is placed on the edge of the image area, according to image attribute information indicating the printing type. either the number of dots of the transparent toner or the use range of the transparent toner is adjusted;
The transparent toner processing device according to any one of claims 1 to 11. The recording medium on which the image forming section has placed the transparent toner can determine whether the transparent toner is placed on the edge of the image area or not, depending on the printing rate information of the toner image on the recording medium. Either the number of dots of the transparent toner placed on the edge or the usage range of the transparent toner is adjusted;
The transparent toner processing device according to any one of claims 1 to 12. an image processing unit that processes edges of image data;
further comprising: the transparent toner processing section according to any one of claims 1 to 13;
The image forming unit further forms an image area of a toner image on the recording medium,
The transparent toner processing section includes:
Based on the edge processing of the image data by the image processing unit, determining whether to place transparent toner on the edge of the image area, the number of dots of transparent toner to be placed on the edge of the image area, and the size of the transparent toner area. adjust any
An image forming apparatus characterized by: The image forming section includes:
forming one or more types of toner images on the recording medium;
The image forming apparatus according to claim 14. comprising a media sensor that determines the type of the recording medium,
The transparent toner processing section includes:
Depending on the glossiness of the recording medium determined by the media sensor, whether or not to place the transparent toner on the edge of the image area, the number of dots of transparent toner to place on the edge of the image area, and use of the transparent toner. adjust any of the ranges,
The image forming apparatus according to claim 14 or 15. The transparent toner processing section includes:
When printing on both sides of the recording medium, depending on double-sided printing, whether or not the transparent toner is placed on the edge of the image area, the number of dots of the transparent toner placed on the edge of the image area, and/or the transparent toner Adjust the usage range of
The image forming apparatus according to any one of claims 14 to 16. an image forming section that forms a transparent toner image on a recording medium;
a transparent toner processing unit that performs processing to place transparent toner on an edge portion of an image area of the toner image on the recording medium;
A transparent toner processing method performed by a transparent toner processing device comprising:
a step in which the transparent toner processing unit selects an edge portion between the image area and the non-image area as an area on which transparent toner is to be placed;
reducing the number of dots on the edge of the area where the transparent toner is placed compared to other areas;
A transparent toner processing method characterized by carrying out. an image forming section that forms a transparent toner image on a recording medium;
a transparent toner processing unit that performs processing to place transparent toner on an edge portion of an image area of the toner image on the recording medium;
A transparent toner processing device equipped with
a step of selecting an edge portion between the image area and the non-image area as an area on which transparent toner is to be placed;
a step of reducing the number of dots at the edge of the area on which the transparent toner is placed and the non-image area compared to other areas;
A transparent toner processing program characterized by executing the following.

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