Information processing system and program

Abstract

To provide a technique of obtaining an expansion / contraction rate of paper relative to the dimensions of the paper in a reference environment.SOLUTION: A predictive model 42 is created that predicts an expansion / contraction rate from an absorption amount based on actual measurements of an expansion / contraction rate of paper when it is in equilibrium at each humidity and an absorption amount in an absorption band due to H-O-H expansion / contraction motion of the paper at that time. A media sensor 10 measures an amount of light absorbed by the paper in the absorption band. An expansion / contraction rate prediction unit 44 receives information about the absorption amount, and obtains an expansion / contraction rate corresponding to the absorption amount, using the predictive model 42. An image correction unit 46 enlarges or reduces an image printed on the paper according to the obtained expansion / contraction rate.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present invention relates to an information processing system and a program. [Background technology]

[0002] Paper expands and contracts depending on the humidity of the environment. The property of how much paper expands and contracts in response to changes in humidity is called humidity expansion rate. The paper industry standard called JAPAN TAPPI No. 28 "Paper and cardboard - Test method for expansion rate due to changes in humidity" defines humidity expansion rate and specifies how to measure it. Japan Industrial Standards and International Organization for Standardization also have standards for the expansion rate of paper depending on humidity.

[0003] The expansion and contraction rate of paper affects print quality by causing paper jams on the paper transport path, curling due to fixing, etc. The expansion and contraction rate of paper varies greatly depending on the variation in conditions for each paper production lot, such as the factory where the paper was produced or the season, or the environment in which the paper is used.

[0004] The standard method for measuring the rate of expansion and contraction involves gradually changing the humidity of the environment in which the paper is placed, allowing the paper to acclimate to each humidity level before measuring the dimensions of the paper, which takes a significant amount of time.

[0005] Although there is no direct relationship between the expansion and contraction rate of paper and humidity, Patent Documents 1 to 3 disclose techniques for predicting the shrinkage of paper due to heating in the fixing unit and using the predicted shrinkage to control double-sided printing.

[0006] The device disclosed in Patent Document 1 includes a temperature measuring unit that measures the in-machine temperature, an image forming unit that forms a toner image and transfers it to paper, a fixing unit that fixes the toner image to the paper, a paper discrimination unit serving as a first detection unit that detects the size of the paper before it passes through the fixing unit, a paper reading unit serving as a second detection unit that detects the size of the paper after it passes through the fixing unit, a shrinkage rate calculation unit that calculates the shrinkage rate of the paper based on the detection results of the first detection unit and the second detection unit, a memory unit that stores shrinkage rate data by in-machine environment that associates the in-machine temperature environment with the shrinkage rate of the paper, and an image correction unit that corrects the formation conditions of the toner image based on the shrinkage rate of the paper stored in the memory unit in association with the in-machine temperature measured by the measurement unit.

[0007] The device disclosed in Patent Document 2 includes a transfer unit that transfers an image formed in an image forming unit onto paper, a fixing unit that heats the paper transported from the transfer unit to fix the image transferred onto the paper, and a paper re-feed path that transports the paper that has passed through the fixing unit back to the transfer unit.The device also includes a detection unit that is disposed downstream of the fixing unit in the paper transport direction and detects the environment within the machine or characteristics of the paper, and a correction value calculation unit that calculates an expected expansion / contraction rate of the paper when the back side image is transferred in the transfer unit from the value detected by the detection unit.

[0008] The device disclosed in Patent Document 3 is an image forming device for double-sided printing, which prints an image of the front side of an original on the front side of a sheet of paper and then prints an image of the back side of the original on the back side of the paper.The device is equipped with a sensor that acquires the characteristics of the paper to be double-sided printed, a shrinkage rate acquisition means that acquires, based on the acquired paper characteristics, a paper shrinkage rate that indicates the proportion of paper shrinkage that occurs from after the image on the front side is printed to after the image on the back side is printed, and a correction means that corrects image data corresponding to the image on the back side based on the acquired shrinkage rate.

[0009] Furthermore, Patent Document 4 discloses a technique for measuring the orientation of fibers in paper or the like by transmitting near-infrared rays through the paper or the like and analyzing the transmitted light. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] JP 2021-105629 A [Patent Document 2] JP 2019-45740 A [Patent Document 3] JP 2009-128874 A [Patent Document 4] Japanese Patent Application Publication No. 7-243187 Summary of the Invention [Problem to be solved by the invention]

[0011] Measuring the expansion rate according to the standard requires a dedicated measuring device and takes a very long time, so such a standardized measuring method is not suitable for cases where you want to know the expansion rate quickly, such as when you want to know the expansion rate of paper at the exact moment when you are going to print on the paper.

[0012] An object of the present invention is to provide a method for determining the expansion / contraction rate of paper relative to the dimensions of the paper in a reference environment. [Means for solving the problem]

[0013] The invention according to claim 1 is an information processing system comprising a processor and a sensor device, wherein the sensor device irradiates light onto a target paper and detects light in an absorption band caused by the expansion and contraction movement of an HOH that has passed through the paper, and the processor determines absorption information representing an amount of absorption of the absorption band by the paper based on a detection result by the sensor device, and determines an expansion and contraction rate of the paper corresponding to the determined absorption information using a prediction model that predicts the expansion and contraction rate of the paper from the absorption information of the absorption band of the paper.

[0014] The invention according to claim 2 is the information processing system according to claim 1, wherein the absorption band is a wavelength band near 1450 nm or near 2900 nm.

[0015] The invention according to claim 3 is the information processing system according to claim 1, characterized in that the processor enlarges or reduces the image to be printed on the paper in accordance with the calculated expansion / contraction ratio.

[0016] The invention of claim 4 is the information processing system described in claim 3, characterized in that the processor calculates the enlargement / reduction ratio of the image to be printed on the front side of the paper and the enlargement / reduction ratio of the image to be printed on the back side of the paper based on the expansion / contraction ratio, and enlarges or reduces the image to be printed on the front side of the paper and the image to be printed on the back side of the paper by the enlargement / reduction ratio calculated for each image, and the enlargement / reduction ratio of the image to be printed on the back side of the paper is determined so that the size of the image on the back side printed after the image on the front side of the paper is fixed is the same as the size of the image on the front side.

[0017] The invention of claim 5 is a program for causing a computer to execute a process of irradiating a target paper with light, acquiring a detection result by a sensor device that detects light in an absorption band due to the expansion and contraction movement of the HOH that has passed through the paper, determining absorption information representing an amount of absorption of the absorption band by the paper from the acquired detection result, and determining an expansion and contraction rate of the paper corresponding to the determined absorption information using a prediction model that predicts the expansion and contraction rate of the paper from the absorption information of the absorption band in the paper. Effect of the Invention

[0018] According to the invention as set forth in claim 1, 2 or 5, it is possible to provide a method for determining the expansion / contraction rate of paper relative to the dimensions of the paper in a reference environment.

[0019] According to the invention as set forth in claim 3, it is possible to print an image of a size according to the current expansion / contraction state of the paper.

[0020] According to the invention as set forth in claim 4, the sizes of images on the front and back of a sheet of paper in double-sided printing can be made the same. [Brief description of the drawings]

[0021] [Figure 1]FIG. 1 is a diagram illustrating an example of a configuration of a system for constructing a predictive model. [Diagram 2] FIG. 10 is a diagram illustrating a processing procedure for constructing a prediction model. [Diagram 3] FIG. 13 is a diagram illustrating the detection values ​​in the 1450 nm band and the measurement results of the expansion / contraction ratio. [Figure 4] FIG. 13 is a diagram illustrating the detection values ​​in the 1940 nm band and the measurement results of the stretching rate. [Diagram 5] FIG. 13 is a graph showing the correlation between the expansion / contraction rate predicted by a regression equation obtained using the 1450 nm band and the actually measured expansion / contraction rate. [Figure 6] FIG. 13 is a graph showing the correlation between the expansion / contraction rate predicted by a regression equation obtained using the 1940 nm band and the actually measured expansion / contraction rate. [Figure 7] FIG. 1 is a diagram illustrating an example of a configuration of an image forming apparatus that uses a prediction model. [Figure 8] 13A and 13B are diagrams illustrating examples of the contents of enlargement / reduction ratio information applied when printing on one side or when printing on the front side of double-sided printing. [Figure 9] 13A and 13B are diagrams illustrating examples of the contents of enlargement / reduction ratio information applied when printing on the back side of a double-sided print. [Figure 10] FIG. 4 is a diagram illustrating a processing procedure executed by the image forming apparatus; [Figure 11] FIG. 2 is a diagram illustrating an example of a hardware configuration of a computer. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] <Principle of expansion / contraction rate prediction> A method for predicting the expansion / contraction rate of paper in an embodiment of the present invention (hereinafter, referred to as an embodiment) will be described.

[0023] Water has the property of absorbing infrared rays, with particularly strong absorption at wavelengths around 1940nm (nanometers), 2900nm, and 1450nm. The 1940nm wavelength is an absorption band caused by the stretching and bending vibration of OH (hydroxyl group). The 2900nm wavelength is an absorption band caused by the stretching vibration of HOH (water molecule). The 1450nm wavelength is half the wavelength band of the 2900nm band, and water also absorbs infrared rays in this vicinity well.

[0024] Since the amount of infrared light absorbed is correlated with the amount of moisture contained in an object, the amount of moisture can be measured by accurately measuring the amount of infrared light absorbed.

[0025] Paper is made primarily of cellulose fibers. Cellulose contains OH groups, and when the paper does not contain moisture, the OH groups of adjacent cellulose fibers are directly bonded together by hydrogen bonds. When the paper contains moisture, the cellulose fibers are loosely bonded together by hydrogen bonds mediated by HOH (water molecules).

[0026] When the humidity level rises and the moisture content of paper increases, the paper expands, and when the moisture content of paper decreases, the paper shrinks. Therefore, the expansion and contraction rate of paper in response to humidity can be measured or predicted from the amount of infrared light absorbed.

[0027] When measuring or predicting the moisture content or shrinkage rate of paper by infrared spectroscopy, it is considered more accurate to use the 1450 nm or 2900 nm band rather than the 1940 nm band. This is because infrared rays in the 1940 nm band are also absorbed by the OH groups of the cellulose fibers that make up paper, whereas infrared rays in the 1450 nm or 2900 nm band are less absorbed by cellulose fibers and are considered to be mostly absorbed by the moisture contained in the paper.

[0028] In this embodiment, the 1450 nm band or the 2900 nm band, or both, are called the wavelength band of interest. In other words, the absorption band due to the expansion and contraction motion of the HOH is called the wavelength band of interest. Then, the amount of infrared light absorbed by the paper in the wavelength band of interest is measured, and the expansion and contraction rate of the paper is calculated based on the measured absorption amount.

[0029] Here, the expansion rate in this embodiment is a value indicating the extent to which the dimensions of the paper in the current environment expand or contract compared to the dimensions of the paper when the environment is in a reference state. The reference state is a combination of a specific temperature (e.g., 20 degrees Celsius) and humidity (e.g., 25%). The dimensions of the paper when the environment is in the reference state (referred to as the reference dimensions) are the dimensions of the paper when it has reached equilibrium in that reference state. The expansion rate may be calculated for both the vertical and horizontal directions of the paper, or may be a single value based on both (e.g., the average of the two). If the dimensions of the paper in the reference state are L0 and the dimensions of the paper in the current state are L1, the expansion rate is calculated using the following formula.

[0030] Stretching rate=100×(L1-L0) / L0

[0031] In this example, the stretch rate is expressed as a percentage: if the paper stretch rate is +1%, the paper is stretched 1% relative to the nominal dimensions, and if it is -1%, the paper is shrunk 1%.

[0032] The dimensions of paper change according to the change in the amount of moisture contained in the paper. The more moisture the paper contains, the more the paper stretches. The amount of moisture contained in the paper is strongly correlated with the amount of infrared radiation absorbed in a wavelength band of interest. Therefore, in this embodiment, a prediction model is constructed to predict or estimate the expansion / contraction rate of paper from the amount of infrared radiation absorbed in a wavelength band of interest that has passed through the paper.

[0033] <System configuration for building predictive models> A system configuration for estimating the expansion / contraction rate of paper from the amount of infrared radiation absorbed in a wavelength band of interest is shown in Fig. 1. This system includes a media sensor 10, an expansion / contraction tester 20, and an information processing system 30 for constructing a prediction model.

[0034] The media sensor 10 is a device for detecting one or more characteristics of a sheet of paper. The characteristics detected by the media sensor 10 include the amount of absorption of light in a wavelength band of interest (i.e., infrared light in this case). To detect this amount of absorption, the media sensor 10 includes a light source 12 that projects light (e.g., infrared light) in a wavelength band that includes the wavelength band of interest toward the sheet of paper, and a photodetector 14 that detects the light emitted from the light source 12 and transmitted through the sheet of paper. The photodetector 14 has a function of extracting and detecting at least the light in the wavelength band of interest. The media sensor 10 may also have a function of detecting one or more characteristics other than the amount of absorption of light in the wavelength band of interest, such as the thickness, surface smoothness, and basis weight of the sheet of paper. The media sensor 10 includes one or more sensors corresponding to the one or more characteristics to be detected.

[0035] The media sensor 10 is incorporated into an image forming device such as a printer or a multifunction device (i.e., a multifunction device having the functions of a printer, scanner, copier, etc.) and is used to detect the characteristics of the paper used in the device. The image forming device controls the printing process according to the detection results of the media sensor 10. The media sensor 10 provided in the system of Figure 1 is the same model as the media sensor installed in the image forming device for which the predictive model that this system is trying to build is used.

[0036] The expansion / contraction tester 20 is a device similar to that used to measure the expansion / contraction ratio or degree of expansion in accordance with standards such as the above-mentioned JAPAN TAPPI No. 28. The expansion / contraction tester 20 has a sealed measurement chamber capable of adjusting humidity to several levels, and is equipped with a mechanism for measuring the dimensions (e.g., vertical length) of a test paper set in the measurement chamber, or the amount of change in the dimensions of the paper in its current state relative to the reference dimensions of the paper (hereinafter collectively referred to as dimensions, etc.). The media sensor 10 is installed in the measurement chamber so as to measure the amount of light absorption in a wavelength band of interest by the paper set in the measurement chamber.

[0037] The amount of absorption in the wavelength band of interest detected by the media sensor 10 and the dimensions of the paper measured by the expansion / contraction test device 20 are input to the information processing system 30. The information processing system 30 calculates the expansion rate relative to the reference dimensions from the input dimensions, and stores the input absorption amount and the expansion rate as a pair. The information processing system 30 constructs a prediction model based on a set of pairs of the absorption amount and the expansion rate measured at each stage when the humidity in the measurement room is changed in stages.

[0038] FIG. 2 illustrates the procedure of the process of constructing a prediction model by this system. In this procedure, an operator sets a sheet in the measurement chamber of the expansion / contraction tester 20, and then operates the expansion / contraction tester 20 to adjust the humidity in the measurement chamber to the initial humidity set in the plan (S10). The plan defines a rule for gradually increasing the humidity, for example, starting from 25% humidity and increasing the humidity in steps of 5% each time up to 80% humidity. After adjusting the humidity in the measurement chamber to the specified humidity, the operator waits for a sufficient time (this time is known) for the sheet to reach equilibrium with the humidity (S12). After S12, the operator reads the values ​​of the sheet dimensions and the like displayed on the display unit of the expansion / contraction tester 20, and inputs the values ​​into the information processing system 30 (S14). Note that, in the case where the display unit of the expansion / contraction tester 20 displays the amount of change in the dimensions of the sheet in the current state relative to the reference dimensions of the sheet as the dimensions of the sheet, the sheet set in the measurement chamber is equilibrated to the reference state before S10, and the dimensions of the sheet at equilibrium are measured and input into the information processing system 30. If the initial humidity in the plan is to be the reference state, then when the humidity is initially equilibrated, the dimensions of the paper (for example, the length itself) at that time may be measured in S14 and input to the information processing system 30.

[0039] Next, the worker causes the media sensor 10 to measure the amount of absorption in the 1450 nm band, reads the value of the measurement result, and inputs it to the information processing system 30 (S16). In this example, the 1450 nm band is used as the wavelength band of interest. The 1450 nm band is a wavelength band with a predetermined width centered around a wavelength of 1450 nm. For example, the 1450 nm band may be a wavelength band with a wavelength range within ±3% of 1450 nm. The 1450 nm band may also be a wavelength band with a wavelength range within ±5% of 1450 nm. The 3% and 5% representing the width of the wavelength band are merely examples.

[0040] At this time, the media sensor 10 projects light of a wavelength band including the 1450 nm band from the light source 12 onto the paper, and the photodetector 14 extracts the light of the 1450 nm band from the light transmitted through the paper and measures its intensity. The media sensor 10 then calculates and outputs the amount of absorption of the 1450 nm band based on the intensity measured by the photodetector 14.

[0041] The information processing system 30 calculates the expansion rate of the paper from the input values ​​such as the paper dimensions, and stores the expansion rate thus obtained in association with the absorption amount input in S16 (S18).

[0042] Next, the worker checks whether measurements for all humidities specified in the plan have been completed (S20), and if not, returns to S10, adjusts the humidity in the measurement room to the next humidity, and repeats the processes from S12 onwards. If it is determined in S20 that measurements for all planned humidities have been completed, the worker instructs the information processing system 30 to execute construction of a prediction model based on the information on pairs of expansion / contraction rates and absorption amounts at each humidity that have been stored up to that point. The information processing system 30 executes a prediction model construction program (S22).

[0043] This program, for example, performs regression analysis on pairs of expansion rate and absorption amount at each humidity level to obtain a regression equation for calculating expansion rate from absorption amount.

[0044] In the above description, the procedures of the work required to construct a prediction model are managed by an operator, but some or all of them may be managed by the information processing system 30. That is, for example, the information processing system 30 may manage humidity control in the measurement room of the stretch testing apparatus 20, and the information processing system 30 may automatically acquire measurement values ​​from the stretch testing apparatus 20 and the media sensor 10.

[0045] An example of the regression equation will be described with reference to FIG. 3. The horizontal axis of the graph shown in FIG. 3 is the spectrum amount, i.e., the detection intensity, of the 1450 nm band, and the vertical axis is the value of the stretch rate actually measured by S14. The detection intensity of the 1450 nm band is the intensity of the light of the 1450 nm band detected by the photodetector 14. The remaining value obtained by subtracting the detection intensity from the intensity of the 1450 nm band component of the light emitted from the light source 12 is the absorption amount of the 1450 nm band by the paper. Since it can be assumed that the intensity of the light output from the light source 12 is constant (and therefore the intensity of the near-infrared light of the 1450 nm band contained in that light is also constant), the detection intensity of the 1450 nm band by the photodetector 14 has a one-to-one relationship with the absorption amount of the 1450 nm band by the paper. Each point plotted on the graph shown in FIG. 3 indicates the measurement result at each humidity, i.e., a pair of the detection intensity of the 1450 nm band and the stretch rate. In the following, the concept of absorption amount will be mainly used for explanation, but since there is a one-to-one relationship between the absorption amount and the detection intensity as described above, the same effect can be obtained even if the detection intensity is used instead of the absorption amount. The absorption amount and the detection intensity are examples of absorption information that represent the absorption amount of the paper for the wavelength band of interest.

[0046] When a linear regression analysis is performed on these points, a straight line 102 that fits the points is obtained. Y=-1.7508X+2.8664 is obtained. X is the detection intensity in the 1450 nm band, and Y is the stretch rate. Each point is quite close to this line 102, so this line 102 represents the group of points with fairly good accuracy. If the horizontal axis is the amount of absorption in the 1450 nm band, the resulting line will rise to the right and the intercept value will also change, but even in this case, the line will represent the group of points (amount of absorption, stretch rate) as well as in the case of Figure 3. This line becomes the prediction model for predicting the stretch rate of paper from the amount of absorption (or detection intensity).

[0047] FIG. 3 focuses on the 1450 nm band. As a comparative example, FIG. 4 shows an example focusing on the 1940 nm band, which is also easily absorbed by water. Each point on the graph in FIG. 4 indicates a pair of the detected intensity of the 1940 nm band (horizontal axis) and the expansion / contraction rate of the paper (vertical axis) at each humidity, obtained when a test similar to that described above is conducted focusing on infrared rays in the 1940 nm band. When a similar regression analysis is conducted on these point groups, a straight line 104, i.e. Y=-36.6991X+1.3118 As can be seen from a comparison with Fig. 3, in the example of Fig. 4, the points are quite far from the line 104. Therefore, the line 104 does not represent the points with high accuracy.

[0048] The graph shown in FIG. 5 shows the correlation between the actual measured value and the predicted value of the stretch rate in the example shown in FIG. 3, focusing on 1450 nm. The horizontal axis shows the actual measured value of the stretch rate, which is found using the above-mentioned procedure. The vertical axis shows the predicted value of the stretch rate, which is the stretch rate (i.e., Y in FIG. 3) found by using the detection intensity of the 1450 nm band detected by the photodetector 14 (i.e., X in FIG. 3) using the above-mentioned prediction model (i.e., line 102 in FIG. 3). Each point plotted on the graph in FIG. 5 represents a pair of the actual measured value and predicted value of the stretch rate at each humidity. When a regression analysis is performed on these points, line 106, i.e., y=1.0023x (x is the actual value, y is the predicted value) All of the plotted points are close to the straight line 106. Therefore, it can be seen that if the straight line 102 in FIG. 3 is used as a prediction model, predictions that are quite close to the actual measured values ​​can be made.

[0049] In contrast, FIG. 6 shows the correlation between the measured and predicted values ​​of the stretch ratio in an example focusing on 1940 nm. In the example of FIG. 6, when a regression analysis is performed on the point group, a straight line 108, i.e., y=0.9697x However, in the example of FIG. 6, many points are far from the line 108, and it is clear that the line 108 does not provide a highly accurate predicted value.

[0050] As described above, the system of FIG. 1 can provide a prediction model that can predict the expansion / contraction rate of paper with high accuracy from the amount of absorption in the 1450 nm band.

[0051] In the above example, the information processing system 30 obtains a linear regression equation as a prediction model by performing regression analysis, but this is merely one example. As another example, the information processing system 30 may construct a prediction model using, for example, a neural network. In this case, the information processing system 30 inputs the absorption amount measured at each humidity in a test to the neural network, and provides the actual measured values ​​of the expansion rate at each humidity as training data, thereby training the neural network to predict the expansion rate from the absorption amount.

[0052] A prediction model is constructed for each type of paper to be used in the assumed image forming device using the system in Fig. 1. The type of paper is expressed as a combination of the paper type (e.g., uncoated paper (such as fine paper) or coated paper) and the basis weight. The basis weight corresponds to the thickness of the paper.

[0053] <Image forming device using a prediction model> Next, an example of an image forming apparatus that uses the prediction model thus constructed will be described with reference to FIG.

[0054] 7 is a device such as a printer or a multifunction peripheral, and includes a printing mechanism 50 that prints an image on paper. The image forming device 200 also includes a media sensor 10 and an information processing system 40.

[0055] The media sensor 10 is the same model device as the media sensor 10 shown in the system of Fig. 1. That is, in the example of Fig. 7, the media sensor 10 also has the function of detecting light in a wavelength band of interest (for example, the 1450 nm band) that has passed through the paper, and determining and outputting the amount of that light absorbed by the paper (or the detected intensity). The media sensor 10 is disposed at a position on the paper transport path in the printing mechanism 50 so that it can project light onto the paper being transported and detect the light that has passed through the paper.

[0056] 7, which is merely an example, the expansion / contraction rate of the paper is predicted based on the measurement by the media sensor 10, and the image to be printed on the paper is controlled to be enlarged or reduced based on the expansion / contraction rate. For this reason, the media sensor 10 is placed in a position where it can measure the paper before the image is printed on it. For example, when an electrophotographic printing mechanism 50 is used, the media sensor 10 is placed somewhere on the paper transport path from the paper feed unit to the photoconductor. Also, in the case of a printing mechanism 50 with a double-sided printing function, the media sensor 10 is placed just before the photoconductor on the transport path through which the paper passes both when printing on the front side and when printing on the back side, so that the same media sensor 10 can measure the paper just before printing on the front side and just before printing on the back side.

[0057] The information processing system 40 is a computer that executes information processing to realize the functions of the image forming apparatus 200. The information processing system 40 controls each part in the image forming apparatus 200, such as the media sensor 10, the printing mechanism 50, and other units not shown. The information processing system 40 also performs processing to predict the expansion / contraction rate of the paper and control the image forming apparatus 200 according to the prediction result. Here, as an example of such control, an example of controlling the size of an image to be printed on the paper according to the predicted expansion / contraction rate will be described. For this control, the information processing system 40 includes a prediction model 42, an expansion / contraction rate prediction unit 44, an image correction unit 46, and an expansion / contraction rate information storage unit 48 as functional modules.

[0058] The prediction model 42 is a prediction model 42 constructed by the information processing system 30 for constructing a prediction model described above. The expansion / contraction rate prediction unit 44 predicts the expansion / contraction rate of the paper from the absorption amount input from the media sensor 10 using the prediction model 42. The image correction unit 46 corrects the image to be printed on the paper in accordance with the expansion / contraction rate predicted by the expansion / contraction rate prediction unit 44. In this correction, the image is enlarged or reduced in accordance with the expansion / contraction rate information stored in the expansion / contraction rate information storage unit 48. The image thus corrected is supplied to the printing mechanism 50 and printed on the paper.

[0059] 8 and 9 show examples of the enlargement / reduction ratio information stored in the enlargement / reduction ratio information storage unit 58. FIG. 8 is an example of the enlargement / reduction ratio information used when printing on one side or when printing on the front side in double-sided printing, and FIG. 9 is an example of the enlargement / reduction ratio information used when printing on the back side in double-sided printing. These examples are examples in which the paper is measured by the media sensor 10 before an image is printed on the front side of the paper, and the enlargement / reduction ratios of images to be printed on the front and back sides of double-sided printing on the paper are calculated based on the measurement results. That is, in this example, the absorption amount of the paper in the wavelength band of interest is measured before printing on the front side, and the expansion / contraction ratio of the paper at the time of measurement calculated from the absorption amount is used to calculate the enlargement / reduction ratios of the front and back images, respectively.

[0060] The expansion / contraction ratio information shown in Figs. 8 and 9 is in table format and is for a type of paper called non-coated paper. Each row of the table indicates a range of the expansion / contraction ratio of the paper, and each column indicates a basis weight range. In the illustrated example, the expansion / contraction ratio is divided into seven ranges from a range of 0.1% or more to a range of 1.0% or more. The basis weight range is a range of the basis weight of the paper, and is represented by a pair of a lower limit and an upper limit of the basis weight of each range. However, in the figure, to avoid complexity, it is represented by a name that indicates the thickness of the paper, such as "thin paper", "plain paper", "medium thickness paper", and "thick paper". The belt temperature shown in the row immediately below the basis weight range is the temperature of the fixing belt that fixes the printed image to the paper, and this belt temperature is automatically determined from the type of paper. In the figure, the belt temperature during the fixing process of plain paper is used as a reference, and the positive and negative temperature difference from that reference is shown as the belt temperature of each basis weight range.

[0061] 8 and 9, the image scaling ratio corresponding to the combination of the stretch ratio range and the basis weight band is registered in the cells where each row and column intersects. A scaling ratio of 100% indicates that the original image is left unchanged with no scaling, a value greater than 100% indicates scaling, and a value less than 100% indicates scaling. For example, a scaling ratio of 100.5% applied when the stretch ratio is 1.0% or greater and the basis weight band is thin paper indicates that the original image is scaled to 100.5% (i.e., 0.5% larger than the original size).

[0062] 8 and 9 are merely examples, but the lowest expected humidity state is set as the reference state, and the size of the image printed on the front side of the paper in the reference state is set as the reference, i.e., 100%. Since other humidities are higher than the humidity in the reference state, the paper stretches when printing on the front side, and the expansion / contraction rate is higher than 100%. In this embodiment, when printing on the front side of single-sided printing or double-sided printing, the size of the image printed on the paper is enlarged or reduced according to how much the paper has expanded or contracted from the reference state at the time of printing. This is why, in the example of FIG. 8, the image expansion rate is increased in sections with larger expansion / contraction rates.

[0063] Therefore, when the same image is printed on paper of the same type, basis weight, and size (e.g., paper from the same production lot), the images on each paper will be the same size when equilibrated to the same environmental conditions after printing, even if the environmental conditions (e.g., humidity) were different when each paper was printed. In other words, variation in the size of the printed image due to differences in the environmental conditions when printed is suppressed.

[0064] In addition, when the average humidity is the reference state, the humidity of the environment during printing may be lower than the reference state, in which case the paper shrinks more than in the reference state. Therefore, in an example in which the average humidity is the reference state, the enlargement / reduction ratio information illustrated in Figures 8 and 9 also includes a section including negative values ​​as a section of the predicted value of the expansion / reduction ratio.

[0065] The enlargement / reduction ratio of each cell in the enlargement / reduction ratio information for the back side shown in FIG. 9 is smaller than the enlargement / reduction ratio of the corresponding cell in the enlargement / reduction ratio information for the front side shown in FIG. 8. This reflects the fact that the moisture in the paper evaporates due to heating in the fixing unit (e.g., fixing belt) when printing on the front side, causing the paper to shrink. The thicker the paper, the more likely it is to shrink, so the reduction in the enlargement / reduction ratio is greater compared to the front side. By using the enlargement / reduction ratio information shown in FIG. 9, the size of the image printed on the back side of the paper can be made the same as the size of the image printed on the front side of the paper. This makes it possible to match the sizes when aligning the registration between the front and back sides.

[0066] The enlargement / reduction ratio information exemplified in FIGS. 8 and 9 may be created by conducting experiments or the like during development of the image forming apparatus.

[0067] In the case of an apparatus configuration that measures the absorption amount of the wavelength band of interest for the paper even at a position after printing on the front side and before printing on the back side, the value of the enlargement / reduction ratio for each cell in the enlargement / reduction ratio information for the back side will be larger than the value exemplified in Fig. 9. This is because the measurement at a position after printing on the front side and before printing on the back side measures the paper in a state where it has shrunk due to the heat fixing of the front side image, and the process of further shrinking the paper (e.g., fixing) is not included between the measurement and the printing of the back side image.

[0068] Next, an example of a procedure of a process executed by the information processing system 40 will be described with reference to Fig. 10. The information processing system 40 executes the procedure illustrated in Fig. 10, for example, every time it picks up a sheet of paper from a paper feed unit and performs a printing process on that sheet.

[0069] In this procedure, first, the expansion / contraction rate prediction unit 44 of the information processing system 40 acquires information on the basis weight of the paper to be printed and the fixing temperature to be applied to that paper (S30). The basis weight information should have been registered in the information processing system 40 by an operator when setting a stack of papers in the paper feeder, for example, so that information can be acquired. Alternatively, the basis weight of that paper may be measured by the media sensor 10. Also, since information on the fixing temperature corresponding to the basis weight of the paper is registered in advance in the information processing system 40, the information processing system 40 can ascertain the fixing temperature from that information.

[0070] Next, the expansion / contraction rate prediction unit 44 of the information processing system 40 acquires the value of the absorption amount in the wavelength band of interest from the media sensor 10 that measured the paper (S32), and determines the expansion / contraction rate of the paper corresponding to that absorption amount (S34) using the prediction model 42. For example, if the prediction model 42 is a regression equation that expresses the relationship between the absorption amount and the expansion / contraction rate, the expansion / contraction rate prediction unit 44 determines the expansion / contraction rate by substituting the absorption amount into the regression equation.

[0071] Next, the image correction unit 46 of the information processing system 40 reads out from the enlargement / reduction ratio information storage unit 48 the enlargement / reduction ratios for the front and back sides that correspond to the combination of the basis weight acquired in S30 and the expansion / reduction ratio calculated in S34 (S36). The image correction unit 46 then enlarges or reduces the image to be printed on the front side and the image to be printed on the back side of the paper by the enlargement / reduction ratio calculated in S36, respectively, and supplies these enlarged or reduced images to the printing mechanism 50 (S38). The printing mechanism 50 prints the images supplied from the image correction unit 46 on the front and back sides of the paper.

[0072] An example has been described above in which the size of an image to be printed on paper is controlled using the expansion / contraction rate of the paper predicted by the expansion / contraction rate prediction unit 44.

[0073] In the example of Fig. 10, the predicted value of the expansion / contraction ratio of the paper obtained from the measurement result before printing on the front side of the paper is used to control the expansion / contraction ratio of the image on not only the front side but also the back side. However, this is only one example. As another example, after the image printed on the front side of the paper is fixed and before printing on the back side, the amount of absorption of the paper in the wavelength band of interest may be measured, the expansion / contraction ratio may be predicted from this absorption amount, and the expansion / contraction ratio of the image on the back side may be controlled according to the predicted expansion / contraction ratio.

[0074] Although the embodiments of the present invention have been described above, these embodiments are merely illustrative. Various modifications are possible within the scope of the technical concept of the present invention. For example, in the example of FIG. 7, the expansion / contraction rate prediction unit 44 is located within the image forming apparatus 200, but the expansion / contraction rate prediction unit 44 may be located outside the image forming apparatus 200. For example, a server that provides the function of the expansion / contraction rate prediction unit 44 may exist on the network, and the information processing system 40 of the image forming apparatus 200 may send the measurement results of the media sensor 10 to the server and obtain the predicted value of the expansion / contraction rate from the server.

[0075] In the above example, the media sensor 10 determines the amount of absorption in the wavelength band of interest, but as another example, the media sensor 10 may detect transmitted light in the wavelength band of interest and output its intensity, and the information processing system 40 may determine the amount of absorption in the wavelength band of interest by the paper from the intensity. In other words, the process of determining the amount of absorption from transmitted light in the wavelength band of interest may be performed by a processor in the media sensor 10 or a processor in the information processing system 40.

[0076] The information processing systems 30 and 40 described above are configured using, for example, a general-purpose computer. As shown in FIG. 11, the computer has a circuit configuration in which a processor 1002, a memory (main storage device) 1004 such as a random access memory (RAM), a controller for controlling an auxiliary storage device 1006 which is a non-volatile storage device such as a flash memory, an SSD (solid state drive), or an HDD (hard disk drive), an interface with various input / output devices 1008, a network interface 1010 for controlling connection to a network such as a local area network, and the like are connected via a data transmission path such as a bus 1012. A program in which the contents of the processing of the above embodiment are described is installed in the computer via a network or the like and stored in the auxiliary storage device 1006. The program stored in the auxiliary storage device 1006 is executed by the processor 1002 using the memory 1004, thereby configuring the information processing mechanism of the present embodiment. The information processing systems 30 and 40 may also include an image processing processor for performing general-purpose or specific-purpose image processing at high speed, a dedicated processor for neural network processing, and the like.

[0077] Furthermore, each of the information processing systems 30 and 40 may be configured with a single computer or multiple computers. For example, some functions of the information processing system 40 may be provided in another computer outside the image forming apparatus 200.

[0078] In each of the above embodiments, the term "processor" refers to a processor in a broad sense, including general-purpose processors (e.g., CPU: Central Processing Unit, etc.) and dedicated processors (e.g., GPU: Graphics Processing Unit, ASIC: Application Specific Integrated Circuit, FPGA: Field Programmable Gate Array, programmable logic device, etc.).

[0079] In addition, the operations of the processor in each of the above embodiments may be performed not only by one processor, but also by multiple processors located at physically separate locations working together. Furthermore, the order of the operations of the processor is not limited to the order described in each of the above embodiments, and may be changed as appropriate.

[0080] (Additional Note) (((1))) A processor and a sensor device, The sensor device irradiates light onto a target paper sheet and detects light that is transmitted through the paper sheet and has an absorption band caused by the expansion and contraction movement of the HOH; The processor, determining absorption information representing an amount of absorption by the paper in the absorption band based on a detection result by the sensor device; determining an expansion / contraction rate of the paper corresponding to the obtained absorption information using a prediction model that predicts an expansion / contraction rate of the paper from absorption information of the absorption band of the paper; Information processing system. (((2))) 2. The information processing system according to claim 1, wherein the absorption band is a wavelength band near 1450 nm or near 2900 nm. (((3))) The processor, enlarging or reducing the image to be printed on the paper in accordance with the calculated expansion / contraction ratio; 2. The information processing system according to claim 1, (((4))) The processor, determining an enlargement / reduction ratio of an image to be printed on the front side of the paper and an enlargement / reduction ratio of an image to be printed on the back side of the paper based on the expansion / reduction ratio, and enlarging or reducing the image to be printed on the front side of the paper and the image to be printed on the back side of the paper by the determined enlargement / reduction ratio for each image; the enlargement / reduction ratio of the image to be printed on the back side of the paper is determined so that the size of the image on the back side to be printed after the image on the front side of the paper is fixed is the same as the size of the image on the front side of the paper; 4. The information processing system according to claim 3. (((5))) A detection result is obtained by a sensor device that detects light in an absorption band caused by the expansion and contraction movement of the HOH and that is transmitted through the paper, and absorption information that represents an amount of absorption by the paper in the absorption band is obtained from the obtained detection result; determining an expansion / contraction rate of the paper corresponding to the obtained absorption information using a prediction model that predicts an expansion / contraction rate of the paper from absorption information of the absorption band of the paper; A program that causes a computer to execute a process.

[0081] According to the information processing system described in (((1))) and the program described in (((5))), it is possible to provide a method for determining the expansion / contraction rate of paper relative to the dimensions of the paper in a reference environment. According to the information processing system described in (((3))), it is possible to print an image of a size according to the current expansion / contraction state of the paper. According to the information processing system described in (((4))), it is possible to match the size of images on the front and back of a sheet of paper in double-sided printing. [Explanation of symbols]

[0082] 10 media sensor, 12 light source, 14 photodetector, 20 expansion / contraction test device, 30 information processing system for constructing a prediction model, 40 information processing system, 42 prediction model, 44 expansion / contraction ratio prediction unit, 46 image correction unit, 48 expansion / contraction ratio information storage unit, 50 printing mechanism, 200 image forming apparatus.

Claims

1. A processor and a sensor device, The sensor device irradiates light onto a target paper sheet and detects light that is transmitted through the paper sheet and has an absorption band caused by the expansion and contraction motion of H-O-H; The processor, determining absorption information representing an amount of absorption by the paper in the absorption band based on a detection result by the sensor device; determining an expansion / contraction rate of the paper corresponding to the obtained absorption information using a prediction model that predicts an expansion / contraction rate of the paper from absorption information of the absorption band of the paper; Information processing system.

2. The information processing system according to claim 1 , wherein the absorption band is a wavelength band near 1450 nm or near 2900 nm.

3. The processor, enlarging or reducing the image to be printed on the paper in accordance with the calculated expansion / contraction ratio; 2. The information processing system according to claim 1 .

4. The processor, determining an enlargement / reduction ratio of an image to be printed on the front side of the paper and an enlargement / reduction ratio of an image to be printed on the back side of the paper based on the expansion / reduction ratio, and enlarging or reducing the image to be printed on the front side of the paper and the image to be printed on the back side of the paper by the determined enlargement / reduction ratio for each image; the enlargement / reduction ratio of the image to be printed on the back side of the paper is determined so that the size of the image on the back side to be printed after the image on the front side of the paper is fixed is the same as the size of the image on the front side of the paper; 4. The information processing system according to claim 3.

5. A detection result is obtained by a sensor device that detects light in an absorption band due to the expansion and contraction movement of H-O-H that has been transmitted through the paper, and absorption information that represents an amount of absorption by the paper in the absorption band is calculated from the obtained detection result; determining an expansion / contraction rate of the paper corresponding to the obtained absorption information using a prediction model that predicts an expansion / contraction rate of the paper from absorption information of the absorption band of the paper; A program that causes a computer to execute a process.

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