JP5846079B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus.

  In recent years, image forming apparatuses have been required to print on high value-added printed materials such as labels and packages. In this package or the like, there are areas that are subjected to processing such as crease processing, perforation (dotted hole for cutting) processing or cutting processing after image formation. Since a force is applied to the image portion during processing such as cutting, the toner of the image is easily peeled off.

  To prevent the toner from being peeled off at the crease processing section, there is a technique for printing a toner having a high fixing strength (for example, see Patent Document 1) and a technique for adjusting the fixing temperature in the fixing device according to the paper (for example, Patent Document 2). It is disclosed.

  For example, Patent Document 3 discloses an image forming apparatus that outputs image data to a print engine after image processing is performed on print data received by the image forming apparatus to make it printable data. Further, for example, Patent Document 4 discloses a technique for specifying a banding tendency that occurs during image forming processing and selecting a screen according to the tendency.

JP 2011-95736 A JP-A-4-315186 JP 2004237758 A JP 2007-81830 A

  An object of the present invention is to provide a technique that can suppress or prevent the toner of an image in an area to be processed after image formation on a recording medium from being peeled off.

  In order to solve the above-described problems, an image forming apparatus according to the first aspect of the present invention includes an image carrier that holds an image formed of toner, and a transfer unit that transfers an image of the image carrier to a recording medium. The type or angle of the screen for image formation is changed in a fixing means for fixing the image transferred to the recording medium and in an image forming area of the recording medium that is processed after image formation. It is characterized by doing.

  According to a second aspect of the present invention, in the first aspect of the present invention, when the angle is changed, a processing direction of a region to be processed after the image formation and a screen direction for the image formation are changed. The angle is changed in a direction in which the angle difference becomes smaller.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, the range for changing the type or angle of the screen for image formation is changed according to the recording medium. To do.

  According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, the image forming area includes a region having a density higher than a predetermined density. Of the regions having a density higher than a predetermined density, the density of the region processed after the image formation is made lower than the density of the region other than the region processed after the image formation. To do.

  According to the first aspect of the present invention, it is possible to suppress or prevent the toner of the image in the area to be processed after image formation on the recording medium from being peeled off.

  According to the second aspect of the present invention, it is possible to more effectively suppress or prevent the toner of the image in the region to be processed after the image formation on the recording medium from being peeled off.

  According to the third aspect of the present invention, it is possible to suppress or prevent the toner of the image from being peeled without deteriorating the appearance of the area to be processed after the image formation on the recording medium.

  According to the fourth aspect of the present invention, it is possible to suppress or prevent the toner of the image in the region to be processed after the image formation from being peeled out of the region having the image density higher than the predetermined density. It becomes possible.

1 is a conceptual diagram of an example of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a block diagram illustrating a configuration of a control unit of the image forming apparatus in FIG. 1. It is the figure which showed an example of print data typically. It is the figure which showed typically an example of the process data given after image formation. It is the figure which showed typically the printing data after screen application. It is the figure which showed typically the process data given after image formation after adding a screen change area | region. It is the figure which showed the image formation data typically.

  Hereinafter, an embodiment as an example of the present invention will be described in detail with reference to the drawings. Note that components having the same function are denoted by the same reference symbols throughout the drawings for describing the embodiment, and the repetitive description thereof will be omitted.

  FIG. 1 is a conceptual diagram of an example of an image forming apparatus 1 according to an embodiment of the present invention.

  The image forming apparatus 1 according to the present embodiment is, for example, a tandem color printer, and includes a plurality of image forming units 20, an intermediate transfer belt (an example of an image carrier) 30, a backup roll 41, and a secondary transfer roll ( An example of transfer means) 42, a pair of paper supply trays 50 a and 50 b, a paper transport system 60, and a fixing device (an example of fixing means) 70 are provided.

  The image forming unit 20 includes, for example, four color image forming units 20Y, 20M, 20C, and 20K that form yellow, magenta, cyan, and black toner images, and a transparent color that transfers, for example, a transparent toner image. Image forming units 20CL and 20CL, and a toner image formed according to image information of each color is primarily transferred to the intermediate transfer belt 30. These six image forming units 20CL, 20Y, 20M, 20C, and 20K are arranged in the order of transparent color, transparent color, yellow, magenta, cyan, and black along the rotation direction of the intermediate transfer belt 30.

  Each image forming unit 20 irradiates a laser beam L onto the photosensitive drum 21, a charging device 80 that charges the surface of the photosensitive drum 21 to a predetermined potential, and a laser beam L on the charged photosensitive drum 21. An exposure device 23 that forms an electrostatic latent image, a developing device 24 that develops an electrostatic latent image formed on the photosensitive drum 21 by the exposure device 23 to form a toner image, and a toner image on the photosensitive drum 21 Is provided with a primary transfer roll 25 for transferring the toner image to the intermediate transfer belt 30 in the primary transfer portion, and a drum cleaner 26 for removing residual toner, paper dust and the like from the surface of the photosensitive drum 21 after the toner image is transferred. A toner cartridge 27 that supplies toner to the developing device 24 is installed above each image forming unit 20.

  The primary transfer roll 25 of each image forming unit 20 is arranged so that the intermediate transfer belt 30 is sandwiched between each photosensitive drum 21. An electric field is formed between the photosensitive drum 21 and the primary transfer roll 25 by applying a transfer bias voltage having a reverse polarity with respect to the charging electrode of the toner to each primary transfer roll 25, and the photosensitive drum 21. The charged toner is transferred onto the intermediate transfer belt 30 by Coulomb force.

  The intermediate transfer belt 30 is a member for sequentially transferring (primary transfer) the toner images of the respective color components formed by the respective image forming units 20 and holding them. The intermediate transfer belt 30 is formed in an endless shape in a state of being laid over a plurality of support rolls 31a to 31f and a backup roll 41, and image forming units 20CL and 20Y for the respective colors while rotating counterclockwise. , 20M, 20C, and 20K toner images are subjected to primary transfer.

  The pair of the backup roll 41 and the secondary transfer roll 42 forms a full-color image by collectively transferring (secondary transfer) the toner images transferred onto the intermediate transfer belt 30 onto a sheet (an example of a recording medium). And is disposed in a state of being opposed to each other with the intermediate transfer belt 30 interposed therebetween. The opposite portion between the backup roll 41 and the secondary transfer roll 42 is a secondary transfer portion.

  The backup roll 41 is rotatably installed on the back side of the intermediate transfer belt 30, and the secondary transfer roll 42 is rotatably installed in a state facing the toner image transfer surface of the intermediate transfer belt 30. The backup roll 41 and the secondary transfer roll 42 are arranged so that their respective rotational axis directions (directions perpendicular to the sheet of FIG. 1) are along each other.

  In transferring the toner image on the intermediate transfer belt 30, a voltage having the same polarity as the charging polarity of the toner is applied to the backup roll 41, or a voltage having a polarity opposite to the charging polarity of the toner is applied to the secondary transfer roll 42. To do. As a result, a transfer electric field is formed between the backup roll 41 and the secondary transfer roll 42, and the unfixed toner image held on the intermediate transfer belt 30 is transferred onto the paper.

  The sheet supply trays 50a and 50b contain sheets of various sizes and thicknesses. The paper in the paper supply trays 50a and 50b is pulled out by a pick-up roll (not shown) of the paper transport system 60, and then the timing is controlled by a resist roll 62 of the paper transport system 60 and introduced into the secondary transfer unit. The toner image is transferred and then conveyed to the fixing device 70 through the conveyance belts 63 and 64 of the paper conveyance system 60.

  The fixing device 70 is a device that fixes an unfixed toner image transferred onto a sheet or the like in a secondary transfer unit to the sheet by thermocompression bonding, and includes a heating roll 70a and a pressure roll provided at a position facing the heating roll 70a. 70b.

  The sheet after the secondary transfer is conveyed to the fixing nip portion between the heating roll 70a and the pressure roll 70b, and is discharged while being sandwiched between the heating roll 70a and the pressure roll 70b. At this time, the paper or the like is heated by the heating roll 70a and is pressed by the pressure roll 70b, whereby the toner image is fixed on the paper or the like. The sheet or the like that has passed through the fixing device 70 is sent to a discharge roll (not shown) through the conveyance belt 65 and discharged to the outside of the image forming apparatus 1.

  Next, FIG. 2 is a block diagram showing a configuration of the control unit 100 of the image forming apparatus 1 of FIG. 2 indicate the flow of processing data applied after image formation.

  The control unit 100 includes a job reception unit 101, a job management unit 102, an image development unit 103, an image processing unit 104, a screen control unit 105, a screen processing unit 106, and an output processing unit 107. Yes.

  The job reception unit 101 is a reception unit that receives the print data DA1 and the processed data DB1 that is applied after image formation. The output of the job reception unit 101 is electrically connected to the input of the job management unit 102, and the print data DA1 and the processed data DB1 received by the job reception unit 101 are sent to the job management unit 102. ing.

  For example, the print data DA1 includes information on the type, basis weight, thickness, and the like of the paper in addition to the information on the image forming area of the paper. Further, the processing data DB 1 applied after image formation has information (processing method, processing direction, etc.) of a region where processing is performed on the paper after image formation.

  Examples of the processing method performed after the image formation include folding processing, sewing machine processing (drilling processing for a broken line for cutting), cutting processing, and the like. The processing direction applied after the image formation indicates the direction of processing (fold line, perforation line, cutting line, etc.) applied to the paper or the like, and is described by position coordinates.

  The job management unit 102 is a management execution unit that manages the input print data DA1 and processing data DB1 and sequentially executes the jobs. The output of the job management unit 102 is electrically connected to the inputs of the image development unit 103, the screen control unit 105, and the output processing unit 107.

  The image development unit 103 is a development generation unit that develops and generates the print data DA1 and the processed data DB1 in accordance with the job management unit 102. The image development unit 103 manages print data (information such as each color density) relating to the image. The output of the image development unit 103 is electrically connected to the inputs of the image processing unit 104 and the screen control unit 105.

  The image processing unit 104 is a processing unit that performs processing such as various corrections and color conversion on the print data generated by the image development unit 103. The output of the image processing unit 104 is electrically connected to the input of the screen processing unit 106, and print data processed by the image processing unit 104 is sent to the screen processing unit 106.

  On the other hand, the screen control unit 105 determines a screen change area (that is, an area to be processed after image formation), and the screen type (coverage density, etc.), direction (screen angle) or the screen of the screen change area. Control to set both. Setting the screen direction and coverage density will be described in detail later.

  The screen control unit 105 includes print data (information such as paper type and basis weight) managed by the job management unit 102, print data (information such as each color density) managed by the image development unit 103, and after image formation. Processing data to be applied (information such as a processing method and a processing direction) is input.

  Further, the output of the screen control unit 105 is electrically connected to the input of the screen processing unit 106, and data relating to the screen change area generated by the screen control unit 105 is sent to the screen processing unit 106. Yes.

  The screen processing unit 106 is a processing unit that applies a screen to the print data subjected to image processing by the image processing unit 104 and performs screen processing. The output of the screen processing unit 106 is electrically connected to the input of the output processing unit 107, and image formation data (output data) generated by the screen processing unit 106 is sent to the output processing unit 107. ing.

  The output processing unit 107 is a processing unit that forms an image on actual paper or the like based on image formation data (output data) sent from the screen processing unit 106 in accordance with an instruction from the job management unit 102.

  Next, an example of a method for creating image formation data according to the present embodiment will be described with reference to FIGS.

  First, the print data DA1 shown in FIG. 3 and the processed data DB1 applied after the image formation shown in FIG. 4 are input to the job receiving unit 101 shown in FIG. 3 and 4 schematically show examples of the print data DA1 and the processed data DB1, respectively.

  The print data DA1 shown in FIG. 3 shows print data for forming a cubic package, for example. The solid area 201A where the toner is solidly applied, and the low coverage where the toner coverage density is lower than the solid area 201A. Density region 202A. The solid area 201A is an image area where the dot state (screen direction, etc.) is not visually recognized when viewed with a microscope, and is an example of an area where the image density is higher than a predetermined density in the image forming area. is there. The solid area 201A is arranged adjacent to a part of the low coverage density area 202A.

  However, here, the solid area 201A is illustrated, but the area is not limited to the solid area. For example, if the area has a density higher than a predetermined density, the image is larger than the solid area. A region having a low density may be used.

  On the other hand, the processing data DB1 applied after image formation shown in FIG. 4 includes a cutting portion (an example of a region to be processed after image formation) 301A indicated by a solid line and a fold line (processed after image formation) indicated by a broken line. For example, 302A. The trimming portion 301A is a cross-shaped contour (outer periphery) portion of a cubic package. Further, the fold line 302A is a bent portion for forming a cubic package.

  Subsequently, the print data DA1 and the processing data DB1 input to the job reception unit 101 are sent to the job management unit 102. In the job management unit 102, the jobs of the print data DA1 and the processed data DB1 are executed in order. The image development unit 103 develops and generates print data and processed data applied after image formation according to the job management unit 102. The image development unit 103 manages information related to the image (information such as each color density). In the image processing unit 104, various corrections, color conversion, and the like are performed on the print data generated by the image development unit 103.

  Subsequently, in the screen processing unit 106, a screen is applied to the print data that has been subjected to image processing by the image processing unit 104, and screen processing is performed. FIG. 5 schematically shows print data DA2 after application of the screen. This print data DA2 has a solid area 201B after application of the screen and a low coverage density area 202B adjacent thereto. Note that the hatching of the low coverage density region 202B schematically indicates the screen direction (screen angle) of the image.

  On the other hand, the screen control unit 105 prints the job management unit 102 (paper type and basis weight information), print data (information such as each color density) of the image development unit 103, and processing performed after image formation. After the screen change area (that is, the area to be processed after image formation) is determined by data (information such as processing method and processing direction), the screen type (coverage density) and direction of the screen change area (Screen angle) or both are set.

  Here, the range in which the type or angle of the screen for image formation is changed is changed according to the paper or the like. Specifically, the processing data DB 1 managed by the image development unit 103 and information such as the sheet of the print data DA 1 managed by the job management unit 102 are used for the range of the screen change area.

  For example, when the processing after image formation is folding, an area having a width of about 5 to 10 times the thickness of the sheet or the like with the crease line as the center is set as the screen change area. This is because the toner peeling width at the crease increases as the thickness of the paper or the like increases.

  Further, for example, when the processing after image formation is perforation processing or cutting processing, the toner peeling width is narrower than in the case of folding processing, so 3 to 10 times the thickness of the sheet with the perforation line or cutting line as the center. An area having a certain width is set as a screen change area.

  Here, FIG. 6 shows processing data applied after image formation after adding the screen change areas 301B and 302B (gray display portions) calculated using the processing data DB1 applied after image formation as described above. DB2 is schematically shown. The screen change areas 301B and 302B are areas having a width proportional to the thickness of the paper or the like with the cutting portion 301A and the fold line 302A as the centers. Thereby, the toner of the image is suppressed or prevented from being peeled off in the region to be processed after the image formation without impairing the appearance in the region to be processed after the image formation.

  However, the determination of the range of the screen change area is not limited to being controlled in accordance with the thickness of the paper or the like, and can be changed in various ways. For example, the screen change area can be controlled in accordance with the elasticity of the paper or the like. good.

  In the present embodiment, in the setting of the screen direction (screen angle) of the screen control unit 105 described above, the screen change areas 301B and 302B (that is, areas processed after image formation) are changed. The angle is changed so that the angle difference between the direction (screen angle) and the processing direction of the cut portions 301A and the folds 302A in the screen change areas 301B and 302B is reduced. Here, for example, the screen direction (screen angle) of the region to be processed after image formation is arranged so as to be along the processing direction of the region to be processed after image formation.

  Normally, the screen direction (screen angle) is determined for each color. Yellow is 0 degrees, cyan is 15 degrees, black is 45 degrees, and magenta is 75 degrees. In the present embodiment, In image formation in an area where processing is performed after image formation, the angle difference between the direction of the screen with the highest coverage density (screen angle) and the processing direction of the area processed after image formation is small. The angle is set in the direction. The screen directions (screen angles) of other colors are changed according to the color having the highest coverage density.

  In addition, if there are two or more colors with the highest coverage density, areas that are processed after image formation in the order of black, cyan, magenta, and yellow, in which toner separation is generally conspicuous with human eyes. The angle is changed so that the angle difference between the screen direction (screen angle) and the processing direction of the region to be processed after image formation is reduced.

  As described above, according to the present embodiment, the angle difference between the screen direction (screen angle) of the region to be processed after image formation and the processing direction of the region to be processed after image formation is small. By changing in this way, it is possible to suppress or prevent the toner of the image from being peeled off in the region to be processed when the paper after the image formation is formed in a cubic package.

  Furthermore, in the present embodiment, in the above-described setting of the coverage density of the screen control unit 105, the coverage density of the solid areas of the screen change areas 301B and 302B (that is, areas processed after image formation) is changed. It is set to be lower than the coverage density of the solid area other than the areas 301B and 302B (that is, the area to be processed after image formation).

  When the coverage density is maximum, the area becomes a solid area, and the above-described method for preventing the toner from being peeled off by controlling the direction of the screen is not effective. On the other hand, even if the coverage density of the solid area in the screen change area is reduced to the maximum 80%, the appearance of the image is not impaired.

  Therefore, in the present embodiment, the coverage density of the solid area in the screen change areas 301B and 302B (that is, the area to be processed after image formation) is reduced to a maximum of 80% as an example. As a result, the method for preventing the toner from peeling off by controlling the direction of the screen is effective.

  As described above, according to the present embodiment, the coverage density of the solid area in the area to be processed after the image formation is made lower than the coverage density of the solid area other than the area to be processed after the image formation. Since the toner peeling suppression prevention method by controlling the screen direction is effective in the area to be processed after image formation, the solid area in the area to be processed after image formation is maintained without deteriorating the appearance of the image. Toner peeling is suppressed or prevented.

  Next, the processing data DB 2 including the information on the screen change area, the screen direction information, and the coverage density information created in the screen control unit 105 is sent to the screen processing unit 106.

  The screen processing unit 106 creates image formation data DAB (output data) in FIG. 7 from the print data DA2 in FIG. 5 and the processed data DB2 in FIG. FIG. 7 schematically shows an example of the image formation data DAB. The image formation data DAB includes solid area 201B information, low coverage density area 202B information, cutting section 301A information, fold line 302A information, and screen change areas 301B and 302B information.

  In the screen change areas (that is, areas to be processed after image formation) 301B and 302B in the solid area 201B and the low coverage density area 202B, the angle difference between the screen direction (screen angle) and the processing direction is small. An angle is set in the direction. In FIG. 7, in the low coverage density region 202B, the screen directions of the screen change regions 301B and 302B are indicated by lines along the cutting portion 301A and the fold line 302A. It is schematically shown that it has changed with respect to (oblique hatching).

  Further, in the screen change areas (that is, areas to be processed after image formation) 301B and 302B in the solid area 201B, the coverage density is lowered to 80%, which is the maximum. In FIG. 7, the screen change areas 301B and 302B in the solid area 201B are indicated by lines along the cutting portion 301A and the fold line 302A, and are lower than the image density of the solid area 201B other than the screen change areas 301B and 302B. This is shown schematically.

  This image formation data DAB is sent to the output processing unit 107. The output processing unit 107 forms a package image on an actual sheet or the like based on the image forming data DAB generated by the screen processing unit 106 in accordance with an instruction from the job management unit 102.

  Although the invention made by the present inventor has been specifically described based on the embodiment, the embodiment disclosed in this specification is an example in all respects and is limited to the disclosed technology. Should not be considered. That is, the technical scope of the present invention should not be construed restrictively based on the description in the above-described embodiment, but should be construed according to the description of the scope of claims. All modifications are included without departing from the technical scope equivalent to the described technique and the gist of the claims.

  For example, in the above-described embodiment, the case where the toner image transferred to the intermediate transfer belt is applied to an intermediate transfer type image forming apparatus that transfers to a sheet is described. However, the present invention is not limited to this. The present invention may be applied to a direct transfer type image forming apparatus that directly transfers a toner image on a drum (an example of an image holding member) onto a sheet or the like by a transfer roll (an example of a transfer unit).

  In the embodiment, the case of forming a color image has been described. However, the present invention may be applied to the case of forming a monochrome image, for example.

  In the above-described embodiment, the case where the recording medium is applied to paper has been described. However, the present invention is not limited to this. For example, the present invention may be applied to various forms such as a film.

  Although the case where the present invention is applied to a color printer has been described above, the present invention may be applied to other image forming apparatuses such as a color copying machine, a facsimile, or an image forming apparatus having these functions.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 20,20Y, 20M, 20C, 20K, 20CL Image forming unit 21 Photosensitive drum 23 Exposure apparatus 24 Developing apparatus 25 Primary transfer roll 30 Intermediate transfer belt 41 Backup roll 42 Secondary transfer roll 50a, 50b Paper supply tray 60 Paper transport system 70 Fixing device 70a Heating roll 70b Pressure roll 80 Charging device 100 Control unit 101 Job reception unit 102 Job management unit 103 Image development unit 104 Image processing unit 105 Screen control unit 106 Screen processing unit 107 Output processing unit 201A, 201B Solid area 202A, 202B Low coverage density area 301A Cutting section 301B Screen change area 302A Crease 302B Screen change area DA1, DA2 Print data DB1, DB2 Processing data DAB Image formation data

Claims (4)

An image carrier for holding an image formed by toner;
Transfer means for transferring an image of the image carrier to a recording medium;
Fixing means for fixing the image transferred to the recording medium;
An image forming apparatus characterized in that, in an image forming area of the recording medium, an area to be processed after image formation changes the type or angle of a screen for image formation.   When the angle is changed, the angle is changed in a direction in which an angle difference between a processing direction of a region to be processed after the image formation and a screen direction for the image formation is reduced. Item 2. The image forming apparatus according to Item 1.   The image forming apparatus according to claim 1, wherein a range in which a type or an angle of the screen for image formation is changed is changed according to the recording medium.   In the case where there is a region having an image density higher than a predetermined density in the image forming region, the density of the region to be processed after the image formation is selected from the regions having a density higher than the predetermined density. The image forming apparatus according to claim 1, wherein the density is lower than a density of a region other than a region to be processed after the image formation.