JP4054160B2 - Printing apparatus and printing method - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a digital printing apparatus and a printing method for converting page data described in a page description language into print data and printing on paper.
[0002]
[Prior art]
Recently, there has been a digital printing apparatus that can convert page data described in a page description language into print data and directly print it on paper. More recently, digital printing apparatuses capable of printing on both sides of paper and digital printing apparatuses capable of multicolor printing on paper have been actively developed.
[0003]
In such a digital printing apparatus, various printing methods are used, but in order to improve productivity, an electrophotographic method capable of executing a printing process at high speed is often used.
[0004]
A general electrophotographic system will be described with reference to FIG. The printing unit 140 is a main process part that performs printing by electrophotography. The photoreceptor 1401 is supported by a housing so as to be rotatable by a drum having a surface coated with a photoconductive substance. First, the charger 1402 uniformly charges the photosensitive member 1401 with a positive or negative charge. The photoconductor 1401 is rotating, and the exposure device 1403 irradiates the surface with light rays. The exposure device 1403 selectively irradiates light so as to form a print image based on the print data.
[0005]
As a result, the uniformly charged photoreceptor 1401 is partially discharged, and as a result, a latent image is formed. Subsequently, the developing device 1404 attaches toner 1405 for forming a print image to the photoreceptor 1401. In the developing device 1404, the toner 1405 is charged with the same polarity as that of the photoconductor 1401, so that the toner 1405 adheres only to the discharged portion of the photoconductor 1401. The photoconductor 1401 continues to rotate and transfers the print image formed by the toner 1405 onto the paper 1400 in the transfer unit 1406. The photosensitive member 1401 continues to rotate, and the remaining toner is cleaned in the cleaning unit 1407. By repeating such a process, formation and transfer of a printed image are continuously performed.
[0006]
On the other hand, the toner 1405 that forms the print image is scattered on the sheet 1400 to which the print image is transferred. Therefore, the sheet 1400 is conveyed to the fixing unit 1410 and the toner is welded to the sheet by heating. This completes the electrophotographic printing.
[0007]
[Problems to be solved by the invention]
When printing is performed by the above-described electrophotographic method, there is a problem in that the paper expands / shrinks due to heat in the process of fixing the toner that forms the print image to the paper by heating, and the print image becomes an unexpected size. is there. In particular, in double-sided printing that prints on both sides of the paper, and digital printing devices that perform multicolor printing by overprinting the paper, the size of the printed image on the front and back sides is not uniform due to the expansion / contraction of the paper, or There arises a problem that the quality of the printed matter is deteriorated, for example, the color to be overprinted is shifted.
[0008]
SUMMARY OF THE INVENTION An object of the present invention is to provide a printing apparatus, a printing method, and a controller for a printing apparatus for solving such problems of the prior art.
[0009]
[Means for solving the problems and their functions and effects]
In order to solve such a problem, the invention according to claim 1 is a printing apparatus that converts page data described in a page description language into print data, and prints on paper based on the print data, A RIP unit that rasterizes page data at a specific scaling ratio and outputs print data; a print image forming unit that forms a print image based on the print data on a sheet with a colorant; and the formed print image on a sheet Prior to the formation of the first print image on the paper, the heat fixing unit that heats for fixing, and the information specifying the correspondence between the number of times of heat fixing of the paper by the heat fixing unit and the shrinkage rate of the paper are stored in advance. A printing device having storage means, The RIP unit classifies and groups page data for each number of heat-fixing processes to be processed later, rasterizes the grouped page data together at a specific scaling ratio, and outputs print data; and , Formed on paper All of multiple printed images The specific scaling factor applied is the reciprocal of the paper expansion / contraction rate corresponding to the number of heat-fixing times specified after the print image is formed, specified with reference to the information. It is said.
[0010]
In the invention disclosed in claim 1, the print data is output by rasterizing the page data by using the reciprocal of the expansion / contraction ratio of the paper by the heat fixing performed after the print image is formed as a specific scaling factor with respect to the page data. Since the print image is formed on the paper with the colorant based on the image, even if the paper expands and contracts due to heat fixing, the print image that has been scaled in consideration of the expansion / contraction ratio of the paper is fixed on the paper. There is an effect that a printed image having a desired size can be obtained.
[0011]
The invention according to claim 2 is applied when forming each print image in the printing apparatus according to claim 1, in which a print image based on a plurality of print data is sequentially formed on the same paper and repeatedly printed by heating and fixing. The specific scaling ratio is characterized by being the reciprocal of the expansion / contraction rate of the paper corresponding to the number of times of heat fixing processed after the print image is formed.
[0012]
In the invention disclosed in claim 2, it is noted that when a plurality of print images are sequentially printed on the same paper, heat fixing to the paper is performed a plurality of times, and a specific application applied when forming each print image By matching the magnification to the reciprocal of the expansion / contraction rate of the paper corresponding to the number of heat treatments performed after the print image is formed, even if the paper expands and contracts due to multiple heat fixings, the original desired size is achieved. There is an effect that a printed image can be obtained.
[0013]
According to a third aspect of the present invention, there is provided a printing apparatus for converting page data described in a page description language into print data and printing on paper based on the print data, and rasterizing the page data at a specific scaling factor. A RIP unit that processes and outputs print data, a print image forming unit that forms a print image based on the print data on a sheet with a colorant, and a heating and fixing unit that heats to fix the formed print image on the sheet In a printing apparatus having The RIP unit classifies and groups page data for each number of heat-fixing processes to be processed later, rasterizes the grouped page data together at a specific scaling ratio, and outputs print data; and , When a print image based on a plurality of print data is sequentially formed on the same paper and printed repeatedly by heating and fixing, a specific scaling factor applied when forming each print image and processing after the print image is formed The specific scaling ratio applied to each print image is determined so that the ratio of the reciprocal of the paper expansion / contraction ratio corresponding to the number of heating and fixing performed substantially coincides at all stages of forming each print image. It is characterized by that.
[0014]
In the invention disclosed in claim 3, the specific scaling ratio applied when the page data is rasterized and output as print data is applied to each print data when a print image is sequentially formed on the same sheet. By making the ratio of the reciprocal of the paper expansion / contraction ratio corresponding to a specific scaling ratio and the number of times of heat fixing substantially coincide at all stages of forming each print image, This is advantageous in that the general relationship is not affected by the expansion and contraction of the paper.
[0016]
Claim 1, claim 3 or In the invention disclosed in claim 4, after the page data is classified and grouped for each heat fixing frequency, a specific scaling ratio is efficiently applied by performing rasterization processing at a specific scaling ratio for each group. There is an effect that print data can be obtained.
[0017]
Also Claim 4 The present invention relates to a printing method in a printing apparatus that converts page data described in a page description language into print data and prints on paper based on the print data, and sequentially rasterizes the page data at a specific scaling factor. An RIP process for processing and outputting print data; a print image forming process for forming a print image based on the print data on a sheet with a colorant; and a heating and fixing process for heating to fix the formed print image on the sheet And a storage step of storing in advance information for identifying the correspondence between the number of times of heat fixing of the paper in the heat fixing step and the shrinkage rate of the paper prior to the formation of the first print image on the paper. In the printing method, In the RIP process, page data is classified and grouped for each number of heat-fixing times to be processed later, the grouped page data is collectively rasterized at a specific scaling ratio, and print data is output. , Formed on paper All of multiple printed images The specific scaling ratio applied is the reciprocal of the expansion / contraction ratio of the paper, which is specified with reference to the information and corresponds to the number of times of heat fixing processed after the printed image is formed. It is said.
[0018]
Claim 4 The invention disclosed in 1 is a method having the same effect as the invention described in claim 1.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
The first embodiment will be described below. FIG. 1 is a diagram showing an example of a printing system when the present invention is implemented. In FIG. 1, a printing system 100 includes a controller 1, a printing machine 2, a network 3, and a front end 4, and the front end 4 is connected to the controller 1 via the network 3. The controller 1 is connected to the printing press 2 via a communication line CL.
[0020]
The front end 4 is a general personal computer, and includes a display unit such as a display, an input unit such as a keyboard, and a storage unit such as a hard disk. The front end 4 creates page data PD by executing software such as a DTP application stored in the storage unit. Then, the document data DD including a plurality of created page data PD is transmitted to the controller 1 via the network 3. The document data DD and page data PD are data expressed in a page description language.
[0021]
The controller 1 rasterizes the page data PD included in the received document data DD to create print data PRD. The print data PRD created by the controller 1 is transmitted to the printer 2 via the communication line CL.
[0022]
Based on the received print data PRD, the printer 2 performs print image formation and heat fixing, and executes printing. The printing machine 2 can perform double-sided printing and multicolor printing by repeating print image formation and heat fixing on the same paper a plurality of times.
[0023]
FIG. 2 is a diagram for explaining the controller 1 in detail. Similarly to the front end 4, the controller 1 is also composed of a general personal computer. Specifically, the controller 1 includes a CPU 11, a display unit 12, an input unit 13, a network I / F 14, a media drive 15, a storage unit 16, and a RAM 17, and is further connected to the printing machine 2 through a communication line CL. ing.
[0024]
The CPU 11 controls the entire controller 1. The display unit 12 displays the state of the controller 1 for the operator or displays necessary for giving an input instruction. The input unit 13 is used to input various information for controlling the controller 1 and includes a keyboard and a mouse. The network I / F 14 is used when receiving document data DD from the front end 4 via the network 3. It is also used when downloading a program executed by the CPU 11 and various image data from a server (not shown) connected to the network 3. The media drive 15 is used when the page data PD created by the front end 4 is received offline. The storage unit 16 can store the page data PD received via the network I / F 14 and the media drive 15 and the print data PRD created by the rasterization process. It is also the role of the storage unit 16 to store a program to be executed by the CPU 11. The communication line CL is used for transmitting print data PRD to the printing machine 2.
[0025]
The RAM 17 is a work area for the CPU 11 to execute a program stored in the storage unit 16 in order to implement the present invention. The RIP unit 171, the page data classification unit 172, and the expansion / contraction rate table 173 are executed by the program executed by the CPU. Function is realized.
[0026]
The RIP unit 171 sequentially interprets the page data PD for each page described in the page description language created by the front end 4 and performs rasterization processing to output print data PRD for each page. If page setting (scaling factor) relating to scaling is performed separately from the page data PD, the RIP unit 171 performs scaling processing on the page data PD according to the setting.
[0027]
The page data classification unit 172 classifies each page data PD every time the print image of the page data PD is formed and subjected to the heat fixing process. This is because the printed images that have undergone the same number of heat-fixing processes are subjected to the scaling process at the same scaling ratio, so that the scaling process is performed collectively. Further, the page data classification unit 172 adds a page setting relating to scaling to each page data group PDG classified for each heating and fixing frequency.
[0028]
The expansion / contraction rate table 173 stores the expansion / contraction rate of the sheet by heat fixing. The CPU 11 refers to the expansion / contraction rate table 173, and the page data classification unit 173 adds page settings relating to scaling to each page data group PDG. The RIP unit 171 performs rasterization processing on the page data PD included in each page data group PDG based on the scaling ratio, and outputs the print data PRD that has been scaled to compensate for paper expansion and contraction by heat fixing. To do. Note that the expansion / contraction rate table 173 may be provided in the storage unit 16.
[0029]
FIG. 3 is a schematic configuration diagram of the printing press 2 connected to the controller 1 by the communication line CL. The printer 2 receives the print data PRD for each page data PD from the controller 1 and sequentially forms a print image of each page data. The printing machine 2 is a printing machine that employs an electrophotographic system, and includes two electrophotographic process units 21 and 22 for the front surface and the back surface. The process unit 21 includes a rotatable photoreceptor 51, and a charger 52, an exposure head 53, a developing unit 54, a transfer unit 55, a charge remover 56, and a cleaner 57 are disposed around the photoreceptor 51. The exposure head 53 includes an LED array and a lens array, and the light source of each LED is selectively ON / OFF controlled based on the print data PRD. As a result, an electrostatic latent image corresponding to the image of each page is formed on the photoreceptor 51. Subsequently, the developing unit 54 develops the electrostatic latent image with toner as a colorant to form a toner image (printed image) on the photoreceptor 51, and the paper P conveyed from the paper feeding unit 61 by the transfer unit 55. Transcript to. The paper P to which the toner image has been transferred is heated by the fixing device 62, whereby the toner image is heated and fixed on the paper P.
[0030]
In the case of single-sided printing, the paper P is discharged to the paper discharge tray 64 as it is. In the case of duplex printing, a toner image is further formed on the back surface of the paper P by the process unit 22 having the same configuration as the process unit 21, and the paper P is again heat-fixed by the fixing device 63 and discharged to the paper discharge tray 64. The
[0031]
In such a printing process, since the paper passes through the fixing units 62 and 63, the heating is performed twice, whereby the paper expands and contracts. Therefore, by setting the expansion / contraction rate of the paper in advance for each number of heating and fixing times, the scaling factor applied to each page data PD can be obtained.
[0032]
FIG. 4 is a diagram for showing the contents of the expansion / contraction rate table 173 stored in the RAM 17 of the controller 1. The paper expansion / contraction rate is a numerical value obtained by an equation (paper size after printing / paper size before printing). By comparing the paper size after heat fixing at the time of printing and the paper size before printing, the expansion / contraction ratio of the paper can be obtained. FIG. 4A is a table showing the expansion / contraction ratio of the sheet when the sheet A of a certain material / characteristic is heated and fixed 1 to 4 times. In this example, the expansion / contraction ratio of the paper A is the first fixing,
(Paper size after printing once / paper size before printing) = 0.98
Thus, the paper A is reduced to 98% of the original paper size after the first printing. Furthermore, in the second fixing,
(Paper size after second printing / paper size before printing) = 0.97
Thus, the paper A is reduced to 97% of the original paper size. Further, the size is reduced to 96% by the third fixing. Here, it is assumed that the paper A is a material having a constant expansion rate regardless of the paper size when heated.
[0033]
FIG. 4B is an expansion / contraction rate table assuming the paper B whose expansion / contraction rate changes for each paper size. In this table, the expansion / contraction rate of each fixing frequency is set for each paper size. FIG. 4C is an expansion / contraction rate table assuming a sheet C having different expansion / contraction ratios in the horizontal and vertical directions of the sheet. In this table, independent expansion / contraction ratios in the horizontal direction and the vertical direction are set for each number of fixings. The expansion / contraction ratio of the paper in the horizontal and vertical directions is calculated using the formula (paper width after printing / paper width before printing) and formula (paper height after printing / paper height before printing). Can be sought. Such an expansion / contraction rate table 173 sets the expansion / contraction rate of the paper obtained by performing the test printing before the printing by the printing machine 2.
[0034]
When rasterizing the page data PD and outputting the print data PRD, if the reciprocal of the paper expansion / contraction ratio is set as a variable magnification with reference to such an expansion / contraction ratio table 173, the expansion / contraction of the paper due to heat fixing is set. A printed image in which the influence is compensated can be obtained. This will be described with reference to FIG.
[0035]
FIG. 5 shows the paper before and after heat fixing and the size of the print image recorded on the paper. In this example, the expansion / contraction ratio of the sheet is 0.95, that is, the case where the sheet is reduced to 95% of the original sheet size by performing heat fixing is illustrated.
[0036]
Assuming that the paper size is 100 × 100 and the original size of the printed image formed on the paper, that is, the size represented by the page data PD is 50 × 50, as shown in FIG. When printing is performed without applying a scaling process, the paper size is reduced to 95% (95 × 95) by heat fixing even if a 50 × 50 print image is formed on the paper. End up. Along with this, the size of the printed image after heat fixing is also reduced by 95% to 47.5 × 47.5.
[0037]
In order to prevent the reduction of the print image due to such heat fixing, the RIP unit 171 rasterizes the page data PD using the reciprocal of the expansion / contraction ratio of the paper as a scaling factor, and outputs the scaled printing data PRD. FIG. 5B shows printed images before and after the heat fixing process when the expansion / contraction ratio of the paper is taken into consideration. Here, the print image formed on the 100 × 100 paper is not the original size of 50 × 50, but the rasterization process with a scaling factor that takes into account the expansion / contraction of the paper, that is, the reciprocal of the paper expansion / contraction ratio of 0.95. A print image is formed based on the print data PRD subjected to the scaling process. The size of this printed image is 52.63 × 52.63. After that, when the paper is reduced by heat fixing, this print image is also reduced by 95%. However, since this print image is subjected to a scaling process corresponding to the expansion / contraction ratio of the paper, printing of 50 × 50 size as the original size is performed. An image can be obtained.
[0038]
FIG. 6 is a diagram for illustrating the relationship among the number of times of heating and fixing, the expansion / contraction ratio, and the scaling factor for each print image formation order (stage) based on the print data PRD.
[0039]
As described with reference to FIG. 3, for example, when performing double-sided printing on a sheet, the sheet undergoes heat fixing twice, and thus expands and contracts in two stages. At this time, the print image formed on the paper in the first stage is most affected by the expansion and contraction of the paper. This is because, in order to make the size of the finally obtained print image coincide with the original size, the scaling factor of the print image formed in the first step is once when fixing the print image of itself. This is because when the printed image formed at the stage of fixing is fixed, it is heated and fixed twice. Accordingly, the print image formed in the first stage (front surface) takes into account the expansion and contraction of the paper by two heat fixings, and the print image formed in the second stage (back surface) is a sheet of paper by one heat fixing. The effect of stretching must be taken into account.
[0040]
Similarly, when a print image of four page data PD is obtained by sequentially repeating print image formation and heat fixing four times on the same sheet, as shown in FIG. 6A, first (first stage) When the printed image PI1 is formed on a sheet, the influence of heat fixing is four times. In the case of forming the second (second stage) print image PI2, the fixing frequency of the third (third stage) print image PI3 is twice, and the fourth (fourth stage) print image PI4 is fixed once. It turns out that. Note that a print image formed based on each page data PD included in the document data DD is subjected to one to four heat fixing processes, so that the page data PD is classified into four groups for each fixing frequency. Can do.
[0041]
FIG. 6B is a table showing the relationship between the number of heat-fixing times to which the print image formed at each stage is applied, the paper expansion / contraction rate determined by the number of heat-fixing times, and the scaling factor applied to the page data PD. It is a thing. The printed image PI1 formed first (first stage) undergoes four heat-fixing steps. For this reason, the expansion / contraction rate CS4 corresponding to the number of times of fixing four times is used for determining the scaling factor. Here, the scaling factor V1 of the printed image PI1 is 1 / CS4, which is the reciprocal of the expansion / contraction rate CS4.
[0042]
Similarly, if the expansion / contraction ratio of the fixing times of once, twice and three is CS1, CS2 and CS3, the second (second stage), the third (third stage) and the fourth (fourth stage) The scaling factors V2, V3, and V4 of the formed print images PI2, PI3, and PI4 are reciprocals of the expansion / contraction ratios of the respective sheets, and are thus determined as follows.
Variable magnification V2 = 1 / CS3
Variable magnification V3 = 1 / CS2
Variable magnification V4 = 1 / CS1
[0043]
At each stage, if printing is performed using the printing machine 2 based on the print data PRD processed at such a variable magnification, even if the paper expands or contracts due to heat fixing, the original page data PD is finally expressed. It is possible to obtain a printed image of the size that has been met. Further, the relative relationship between the sizes of the printed images formed at the respective stages substantially matches the relationship expressed by the original page data PD.
[0044]
In order to prevent at least the relative relationship between the sizes of a plurality of print images to be printed on the same sheet from being affected by the expansion and contraction of the sheet, each scaling factor should satisfy the following relationship: .
V1: V2: V3: V4 = 1 / CS4: 1 / CS3: 1 / CS2: 1 / CS1
This relationship
V1: 1 / CS4 = V2: 1 / CS3 = V3: 1 / CS2 = V4: 1 / CS1
It can also be expressed as That is, the ratio between the scaling factor and the expansion / contraction rate is substantially equal at all stages. Therefore, the scaling factor at each stage may be set so as to satisfy the above relationship.
[0045]
The scaling factor of each stage that satisfies this relationship is, for example,
Variable magnification V1 = 1
Variable magnification V2 = CS4 / CS3
Variable magnification V3 = CS4 / CS2
Variable magnification V4 = CS4 / CS1
It is.
[0046]
In this case, a print image having the same size as that represented by the original page data PD cannot be formed, but the relative relationship between the sizes of the print images at each stage can be substantially matched. Generation of misregistration in overprinting such as in color printing can be prevented.
[0047]
"Application example of the present invention by a duplex printer"
FIG. 7 is a flowchart for explaining the operation of the controller 1 when the printing machine 2 performs the printing process. In step S1, the controller 1 receives document data DD including a plurality of page data PD from the front end 4 via the network 3. The page data PD is data described in a page description language, and is described based on, for example, the specification of PostScript (registered trademark of Adobe Systems Incorporated).
[0048]
In step S2, the operator selects the type and size of paper used for printing. The operator can select a sheet to be used for printing by operating the input unit 13 of the controller 1. Further, if the document data DD includes information on the paper type / size, the document data DD may be configured to be automatically selected based on the information.
[0049]
In step S3, the operator sets the print image formation number P as the number of print images formed on the same sheet. Since the printing machine 2 shown in FIG. 3 can perform monochrome printing on the front and back surfaces of the paper, the print image formation number P is “2”, which is the sum of the front and back surfaces.
[0050]
In step S4, the page data PD is classified for each affected number of fixing times. The number n of fixing can be an integer between “1” and the number P of printed image formations. When the total number of page data PD is 2 m and the number of print image formations P is “2”, the CPU 11 executes the function of the page data classification unit 172, thereby printing 1, 3, 5, 7, ...... Page data PD (1), PD (3), PD (5), PD (7) describing 2m-1 pages. PD (2m-1) is temporarily stored as an odd page data group PDGo. Is stored in the storage unit 16. On the other hand, page data PD (2), PD (4), PD (6),... PD (2m) describing even pages are temporarily stored in the storage unit 16 as even page data group PDGe.
[0051]
Step S5 is a step of determining the scaling factors V1 and V2 for the odd page data group PDGo and the even page data group PDGe classified in step S4, respectively. The CPU 11 obtains a scaling factor applied to the odd page data group PDGo by referring to the sheet expansion / contraction rate table 173 selected in step S2. The scaling ratio V1 of the odd-numbered page data group PDGo can be determined by reading the expansion / contraction ratio of the paper corresponding to the heat fixing frequency “2” from the expansion / contraction ratio table 173 and calculating the reciprocal thereof. Further, the scaling factor V2 of the even-numbered page data group PDGe can be determined by reading the expansion / contraction rate CS1 having the fixing number n of “1” from the expansion / contraction rate table 173 and calculating the reciprocal thereof.
[0052]
Further, in this step, a scaling process command is prepared based on the determined scaling ratios V1 and V2. The scaling process command is described according to the same rule as that describing the page data PD. For example, in the case of PostScript, this scaling command is for the odd page data group PDGo.
V1 dup scale%
It becomes. Similarly, the scaling command for the even page data group PDGe is
V2 dup scale%
It becomes.
[0053]
If the paper expansion / contraction rate CS differs between the horizontal and vertical directions,
Vx1 Vy1 scale%
Can be described. Here, Vx1 and Vy1 are the expansion and contraction rates in the horizontal and vertical directions, respectively.
[0054]
In subsequent step S6, the RIP unit 171 performs rasterization processing on the odd page data group PDGo. The CPU 11 first outputs the scaling process command for the odd page data group PDGo prepared in step S5 to the RIP unit 171, and then outputs the page data PD for the odd page data group PDGo. The RIP unit 171 sequentially interprets the scaling process command and the page data PD, performs rasterization processing, and outputs an odd print data group PRDGo. At this time, since the RIP processing unit 171 performs the scaling process and the rasterizing process with the scaling ratio described by the scaling process command, that is, the reciprocal of the sheet stretching ratio, the odd print data group PRDGo that compensates for the sheet stretching ratio. Can be obtained. The output odd print data group PRDGo is temporarily stored in the storage unit 16. Alternatively, the odd print data group PRDGo may be transferred to the printer 2 via the communication line CL.
[0055]
Similarly, in step S7, the RIP unit 171 performs rasterization processing on the even page data group PDGe. The CPU 11 outputs the scaling process command for the even page data group PDGe prepared in step S5 to the RIP unit 171, and then outputs the page data PD for the even page data group PDGe. The RIP unit 171 sequentially interprets the scaling process command and the page data PD, rasterizes them, and outputs an even print data group PRDGe. At this time, since the RIP processing unit 171 performs the scaling process and the rasterization process with the scaling ratio described by the scaling process command, that is, the reciprocal of the sheet stretching ratio, the even print data group PRDGe that compensates for the sheet stretching ratio. Can be obtained. The output even print data group PRDGe is temporarily stored in the storage unit 16. Alternatively, the even print data group PRDGe may be transferred to the printing machine 2 via the communication line CL. Of course, either of steps S6 and S7 may be executed first.
[0056]
In step S8, the controller 1 transfers the odd print data group PRDGo and the even print data group PRDGe output in steps S6 and S7 to the printing machine 2, respectively. The printing machine 2 sequentially forms print images based on the print data PRD included in the odd-numbered page data group PRDGo on the front surface of the paper in the process unit 21 for front side printing, while the process unit 22 for back side printing Print images based on the print data PRD included in the even page data group PRDGo are sequentially formed on the back surface of the paper.
[0057]
As described above, the size of the print image formed by the front surface process unit 21 takes into account the expansion and contraction of the paper due to the heat fixing twice, and the print image formed by the back surface process unit 22. Since the size of the paper takes into account the expansion and contraction of the paper by one heating and fixing, the finally obtained print image is not affected by the expansion and contraction of the paper and is the original size expressed by the page data PD. It becomes.
[0058]
In each stage, when the scaling ratio is determined so that the ratio between the scaling ratio and the reciprocal of the expansion / contraction ratio of the paper substantially matches, the relative size of the print image formed in each stage is determined. The relationship is equal to the relative size relationship represented by the page data PD. Therefore, in the case of double-sided printing as in this application example, it is possible to obtain a good-looking printed material without the imbalance between the sizes of the printed images formed on the respective surfaces.
[0059]
"Application example of the present invention by a multicolor printing machine"
Next, an embodiment when the present invention is applied to multicolor printing will be described. FIG. 8 is a diagram for explaining the configuration of the controller 200 used when performing multicolor printing.
[0060]
In FIG. 8, a controller 200 includes a CPU 201, a display unit 202, an input unit 203, a network I / F 204, a media drive 205, a storage unit 206, and a RAM 207, and is connected to the printing machine 400 via a communication line CL. Yes. The functions of the CPU 201, display unit 202, input unit 203, network I / F 204, media drive 205, storage unit 206, and communication line CL are the same as the functions of the controller 1 described in FIG.
[0061]
A RAM 207 is a work area for the CPU 201 to execute a program stored in the storage unit 206. Functions of the RIP unit 2071, the scaling factor setting unit 2072, the expansion / contraction rate table 2073, and the processing counter 2074 are executed by the program executed by the CPU 201. To realize.
[0062]
The RIP unit 2071 performs rasterization processing by sequentially interpreting the page data PD described in the page description language created by the front end 4. The RIP unit 2071 executes a scaling process for the page data PD when page setting is performed for scaling. A scaling ratio setting unit 2072 sets a scaling ratio for each page data PD to be rasterized with reference to the scaling ratio table 2073. The expansion / contraction rate table 2073 stores the expansion / contraction rate of the sheet for each heating and fixing number. Further, depending on the case, the expansion / contraction rate of the paper may be stored for each paper type and size. The scaling factor setting unit 2072 refers to the expansion / contraction rate table 2073 based on the number of times of heating and fixing the sheet on which the print image is formed by the page data PD to be processed, and determines the scaling factor applied to the page data PD. . The variable magnification is the reciprocal of the expansion / contraction rate of the paper.
[0063]
The RIP unit 2071 can perform rasterization processing based on the scaling ratio determined for each page data PD, and can output print data PRD that has been scaled according to the expansion / contraction ratio of the paper. The processing counter 2074 is a counter for counting the page data PD included in the document data DD, and is incremented by “1” every time the rasterizing process for the page data PD is completed. The CPU 201 can confirm the end of the rasterizing process for all the page data PD included in the document data DD by comparing the processing counter 2074 with the total number mm of page data PD included in the document data DD.
[0064]
FIG. 9 is a diagram for explaining the printing press 400 connected to the controller 200 via the communication line CL. The printing machine 400 is for performing two-color double-sided printing, and is equipped with process units 401, 402, 403, and 404 having the same functions as the process units 21 and 22 in the printing machine 2 shown in FIG. Yes. Here, the process units 401 and 402 perform printing with the toner of the color CL1, and the process units 403 and 404 perform printing with the toner of the color CL2.
[0065]
In this printing machine 400, two-color double-sided printing is performed as follows. The print data PRD of each page is transmitted from the controller 200 to the printing machine 400 together with a command for instructing printing. The print data PRD can be classified into front surface print data PRDsa, front surface print data PRDsb, back surface print data PRDra, and back surface print data PRDrb for performing two-color duplex printing.
[0066]
The front surface print data PRDsa and the back surface print data PRDra are print data for forming a print image with the color CL1, and the front surface print data PRDsb and the back surface print data PRDsb are print data for forming a print image with the color CL2. The front surface print data PRDsa and the back surface print data PRDra are printed by the process units 401 and 402, respectively. As a result, the front surface print data PRDsa and PRDsb and the back surface print data PRDra and PRDrb are printed on the front surface of the paper, and as a result, two-color printing is performed on both surfaces of the paper.
[0067]
In such a printing process, the paper passes through 64 and 65 in addition to the fixing units 62 and 63, so that the heat fixing is performed four times, whereby the paper expands and contracts stepwise. Therefore, it is necessary to obtain the scaling ratio when rasterizing each page data PD with reference to the paper expansion / contraction rate table 2073 and output the print data PRD. In other words, the print images formed by the process units 401, 402, 403, and 404 need to be scaled by the reciprocal of the sheet expansion / contraction rate of 4, 3, 2, and 1, respectively. There is.
[0068]
FIG. 10 is an operation flowchart of the controller 200 when performing such two-color duplex printing. In step S11, the controller 200 receives document data DD including a plurality of page data PD. In this case, the page data PD included in the document data DD includes page data PDsa and PDsb for printing with colors CL1 and CL2 on the front side of the paper, and page data for printing with colors CL1 and CL2 on the back side of the paper, respectively. Includes PDra and PDsb. Assume that print data PRD for printing four page data PD on the same sheet is output based on these page data. This step also identifies that the total number of page data PD of the received document data DD is mm.
[0069]
In step S12, a paper type and size selection process is executed as in step S2 described in FIG. In step 13, the same print image formation number P is set. When printing on both sides of the printer 2002 color shown in FIG. 9, the print image formation number P is set to “4”. In addition, the page data PD is rearranged so that the front surface print data PRDsa, the back surface print data PRDrb, the front surface print data PRDsb, and the back surface print data PRDrb are in this order.
[0070]
In step S14, a processing counter PRTC for counting the number of sheets to be printed is initialized, and “1” is set. In step S15, the controller 200 rasterizes the page data PD at a scaling factor corresponding to the sheet expansion / contraction rate depending on the number of heat fixing.
[0071]
The processing in step S15 will be described in detail with reference to FIG. In step S51, a variable i for counting the number of page data PDs to be printed on the same sheet is initialized to “1”. In step S52, the value of the variable i is compared with the print image formation number P, thereby determining whether or not all the page data PD to be printed on the current common sheet has been processed. If the value of the variable i is equal to or greater than the print image formation number P, it is determined that the rasterization processing of all the page data PD printed on the common sheet is completed, and this routine ends. On the other hand, if the value of the variable i is smaller than the print image formation number P, it is determined that the processing of all the page data PD has not been completed, and the process proceeds to step S53.
[0072]
Step S53 is a step for obtaining the number n of heat fixing times of the paper on which the print image based on the current page data PD to be rasterized is formed. In the printing machine 400 shown in FIG. 11, print images of four page data PD are formed in stages on one sheet and fixed by heating. The printed images formed in the first, second, third, and fourth stages are subjected to heat fixing four times, three times, two times, and one time, respectively. Generally expressing this, the number n of heat-fixing times that the print image formed in the i-th stage is affected is expressed by the following equation:
n ← P−i + 1
Can be expressed as
[0073]
Subsequently, in step S54, the CPU 201 obtains the sheet expansion / contraction rate CS corresponding to the heating / fixing number n obtained in step S53 from the expansion / contraction rate table 2073. In step S55, the CPU 201 rasterizes the page data PD by the RIP unit 2071 using the reciprocal of the expansion / contraction rate CS acquired in step S54 as the scaling factor V.
[0074]
Subsequently, in step S56, the variable i is incremented by "1", and the process returns to step S52. Note that steps S52 to S56 are repeated until the processing of all the page data PD formed on the same sheet is completed. In the case of the two-color double-sided printing shown in FIG. 9, the loop composed of steps S52 to S56 is performed four times.
[0075]
Returning to the flowchart of FIG. 10, in step S16, the processing counter PRTC is incremented by “1”. In step S17, the processing counter PRTC is compared with the total number mm of page data PD. If the inequality {(processing counter PRTC) <(total page data mm)} is satisfied, the process returns to step S15 to repeat the rasterizing process in order to form a print image on the next sheet. Do. When the processing counter PRTC is equal to or greater than the total number of pages mm, the process proceeds to step S18.
[0076]
In step S18, the printing press 400 performs printing based on the print data PRD output by the rasterization process performed in step S15.
[0077]
The printed matter thus obtained forms a printed image having a size substantially the same as the size represented by the page data PD even if the paper expands and contracts due to heat fixing. Further, since the size of the two-color printed image formed on each surface is substantially the same as the original size, no color misregistration occurs. In addition, since the scaling process for compensating for the expansion and contraction of the paper is performed when the page data is rasterized, the image quality does not deteriorate due to the scaling process.
[0078]
In the application example of the present invention by this multi-color printing machine, in step S55, the heat fixing that is processed after the print image corresponding to the page data PD is formed as the variable magnification applied to each page data PD. Although the reciprocal of the expansion / contraction ratio of the number of sheets is used, as in the example described in the application example of the present invention by the above-described double-sided printing machine, the ratio between the expansion / contraction ratio of the sheet and the scaling ratio substantially matches at each stage. In this way, the scaling factor of each stage may be determined. In this case, it is not possible to form a print image having the same size as that represented by the original page data PD, but the relationship between the relative sizes of the print images at the respective stages is shown in the relative internal view of the original page data. Since the relationship can be matched, it is possible to prevent the occurrence of plate misregistration in the case of multiple colors or overprint printing.
[0079]
[Modification]
In the above embodiment, heat fixing in a printer using an electrophotographic process has been described as an example. However, after a printed image is formed by an inkjet method or the like, the paper is heated to be fixed or glossed. It can be applied to various technologies.
[0080]
In the printing apparatus described with reference to FIG. 3, for example, when the total number of pages to be printed is an odd number, for example, the total number of printed pages is 3, the paper on which the last third page is printed needs to be fixed only once. Even when such control is performed and output to the printing press, it is considered that fixing is performed twice, and the scaling factor for outputting the print data PRD to be printed on the third page is not suitable for the actual situation. It will be. In order to prevent this, if the total number of printed pages is an odd number of pages, the fixing number n of the last page may be determined to be 1. In this way, a printed image having a more accurate size can be obtained.
[0081]
Similarly, even in the printing apparatus described with reference to FIG. 11, when the total number of pages to be printed in two colors is an odd number, for example, the total number of printed pages is three pages, the sheet on which the last third page is printed is fixed only twice. There is no need to do. Even when such control is performed and output to the printing press, it is assumed that fixing is performed four times, and the scaling factor for outputting the print data PRD to be printed on the third page is not suitable for the actual situation. It will be. In order to prevent this, if the total number of printed pages is an odd number of pages, the number n of fixing times of the last page may coincide with the number P of printed image formations. In this way, a printed image having a more accurate size can be obtained.
[0082]
Further, regarding the setting of the expansion / contraction rate tables 173 and 2073, the sheet size is measured each time printing is performed by attaching a sheet size measuring unit to the sheet conveyance path of the printing machines 2 and 400, and the measurement result is used as the expansion / contraction rate table 173. And 2073 may be reflected. In this way, a more accurate expansion / contraction rate can be obtained, and thus a printed image having a more accurate size can be obtained.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a configuration of a printing system.
FIG. 2 is a block diagram for illustrating a configuration of a controller of the printing system from a functional aspect.
FIG. 3 is a diagram illustrating a configuration of a double-sided printing machine.
FIG. 4 is a diagram for illustrating a configuration of an expansion / contraction rate table.
FIG. 5 is a diagram illustrating that a print image that is free from the effects of paper expansion / contraction can be obtained by setting the reciprocal of the paper expansion / contraction rate as a variable magnification.
FIG. 6 is a diagram illustrating a relationship between the expansion / contraction ratio and the number of fixing times of a sheet when a print image is formed on the sheet, and the order of print image formation based on print data PRD and a scaling ratio.
FIG. 7 is a flowchart for explaining the operation of the controller 1 in the double-sided printing machine.
FIG. 8 is a block diagram illustrating a configuration of a controller of the printing system from a functional aspect.
FIG. 9 is a diagram illustrating a configuration of a multicolor printing machine.
FIG. 10 is a flowchart for explaining the operation of the controller 200 in the multicolor printing machine.
FIG. 11 is a flowchart for explaining in detail rasterization processing in the controller 200;
FIG. 12 is a diagram for explaining a general electrophotographic system.
[Explanation of symbols]
1,200 controller
2,400 printing machine
11, 201 CPU
13, 203 Input section
14, 204 Network I / F
16, 206 storage unit
171, 2071 RIP section
172 Page classification part
173, 2073 Stretch rate table
2072 Variable magnification setting section
2074 processing counter
DD Document data
PD page data
PDo Odd page data group
PDe Even page data group
PDsa front page data
PDsb Back page data
PDsa front page data
PDsb Front page data
PDra Back page data
PDrb Back page data
PRDGo Odd page print data group
PRDGe even page print data group
PRDs Surface print data
PRDr Back side print data
PRDsa surface print data
PRDsb Surface print data
PRDra Back side printing data
PRDrb Back side print data

Claims (4)

A printing apparatus that converts page data described in a page description language into print data, and prints on paper based on the print data,
A RIP unit that rasterizes the page data at a specific scaling ratio and outputs print data;
A print image forming unit that forms a print image based on the print data on paper with a colorant;
A heating and fixing unit that performs heating to fix the formed printed image on a sheet;
Storage means for preliminarily storing, prior to the formation of the first print image on the paper, information specifying the correspondence between the number of times of heat fixing of the paper by the heat fixing unit and the shrinkage rate of the paper;
In a printing apparatus having
The RIP unit classifies and groups page data for each number of heat-fixing processes to be processed later, rasterizes the grouped page data together at a specific scaling ratio, and outputs print data; and ,
The specific scaling ratio applied to all of a plurality of print images formed on the paper is a paper corresponding to the number of times of heat fixing processed after the print image is formed, specified with reference to the information. A printing apparatus characterized by being a reciprocal of the expansion / contraction ratio. When a print image based on a plurality of print data is sequentially formed on the same sheet and printed repeatedly by heating and fixing, a specific scaling ratio applied when forming each print image is processed after the print image is formed. The printing apparatus according to claim 1, wherein the printing apparatus is a reciprocal of the expansion / contraction rate of the paper corresponding to the number of times of heat fixing. A printing apparatus that converts page data described in a page description language into print data, and prints on paper based on the print data,
A RIP unit that rasterizes the page data at a specific scaling ratio and outputs print data;
A print image forming unit that forms a print image based on the print data on paper with a colorant;
A heating and fixing unit that performs heating to fix the formed printed image on a sheet;
In a printing apparatus having
The RIP unit classifies and groups page data for each number of heat-fixing processes to be processed later, rasterizes the grouped page data together at a specific scaling ratio, and outputs print data; and ,
When a print image based on a plurality of print data is sequentially formed on the same paper and printed repeatedly by heating and fixing, a specific scaling factor applied when forming each print image and processing after the print image is formed The specific scaling ratio applied to each print image is determined so that the ratio of the reciprocal of the paper expansion / contraction ratio corresponding to the number of heating and fixing performed substantially coincides at all stages of forming each print image. A printing apparatus. A printing method in a printing apparatus for converting page data described in a page description language into print data, and printing on paper based on the print data,
RIP process for sequentially rasterizing page data at a specific scaling ratio and outputting print data;
A print image forming step of forming a print image based on the print data on paper with a colorant;
A heating and fixing step of heating to fix the formed printed image on paper;
A storage step of storing in advance information for specifying the correspondence between the number of times of heat fixing of the paper in the heat fixing step and the expansion / contraction ratio of the paper prior to the formation of the first print image on the paper;
In a printing method having
In the RIP step, page data is classified and grouped for each number of heat-fixing processes to be processed later, the grouped page data is collectively rasterized at a specific scaling ratio, and print data is output. ,
The paper corresponding to the number of times of heat fixing processed after the print image is formed, in which the specific scaling ratio applied to all of the plurality of print images formed on the paper is specified with reference to the information. A printing method characterized by being a reciprocal of the expansion / contraction rate.

Images