JP4957449B2 - Deformed curvature predicting device, medium conveying device, image forming apparatus, and deformed curvature predicting program - Google Patents

Description

  The present invention relates to a modified curvature prediction apparatus, a medium transport apparatus, an image forming apparatus, and a modified curvature prediction program.

  In general, it is known that a recording medium typified by printing paper used in an image forming apparatus has a change in hardness characteristics depending on environmental conditions such as temperature and humidity. For example, when the water content is large, even a recording medium having high flexibility is cured by increasing the bonding force of the composition structure in the medium due to high temperature or low humidity around the medium. Such a change in the hardness characteristic of the recording medium is a factor that causes deformation (for example, deformation called curl) in the shape of the recording medium due to the influence of the difference in shrinkage between the front and back surfaces.

  As for the deformation of the recording medium, conventionally, when the behavior of the recording medium is simulated, the deformation shape is expressed relatively simply (for example, refer to Patent Document 1), and the temperature of the heat fixing device and the sensor of the water content of the paper It has been proposed that a deformation occurrence state is predicted from a detection result or the like and the deformation is appropriately corrected (see, for example, Patent Document 2).

JP 2005-346500 A JP 2005-170525 A

  The present invention relates to a deformed curvature prediction apparatus and a medium transport apparatus capable of performing accurate deformation prediction as compared with the case where the deformation curvature of a recording medium is calculated without considering the contribution of both the change in curvature and the change in viscoelasticity. An object of the present invention is to provide an image forming apparatus and a deformation curvature prediction program.

The present invention is a deformed curvature predicting device, a medium conveying device, an image forming apparatus, and a deformed curvature predicting program devised to achieve the above object.
According to a first aspect of the present invention, there is provided a curvature history acquisition unit that obtains information relating to curvature change over time of a recording medium as curvature history information; Based on the elasticity history acquisition means, the curvature history information obtained by the curvature history acquisition means and the viscoelastic history information obtained by the viscoelastic history acquisition means, the internal stress of the recording medium that changes over time is integrated. An internal stress distribution calculating means for calculating the internal stress distribution of the recording medium after the lapse of time, and a deformation curvature calculating means for calculating a deformation curvature of the recording medium that balances with the internal stress distribution obtained by the internal stress distribution calculating means. It is a deformation | transformation curvature prediction apparatus characterized by providing.
The invention according to claim 2 is characterized in that the viscoelasticity history acquisition unit is configured such that the viscoelasticity change dependency of the recording medium with respect to at least one of the temperature, water content, or deformation amount of the recording medium, and the at least one time lapse. The deformation curvature prediction apparatus according to claim 1, wherein the viscoelastic history information is obtained on the basis of a change amount by.
The invention according to claim 3 is the deformation curvature prediction apparatus according to claim 1 or 2, wherein the deformation curvature calculation means includes the influence of the weight of the recording medium in the condition of balance.
According to a fourth aspect of the present invention, there is provided a medium carrying means for carrying a recording medium, and a curvature history for obtaining, as curvature history information, information relating to a change in curvature of the recording medium over time in the course of carrying the recording medium by the medium carrying means Obtaining means, viscoelasticity history obtaining means for obtaining information relating to viscoelasticity change of the recording medium over time as viscoelasticity history information, curvature history information obtained by the curvature history obtaining means, and the viscoelasticity history obtaining means. Internal stress distribution calculating means for calculating the internal stress distribution of the recording medium after the passage of time, by integrating the internal stress of the recording medium that changes over time based on the viscoelastic history information, and the internal stress A deformation curvature calculating means for calculating a deformation curvature of the recording medium that balances the internal stress distribution obtained by the distribution calculating means, and a deformation curvature calculated by the deformation curvature calculating means. One recording to reduce the amount of deformation of the paper deformation in the time after the recording medium was added, a medium transport device, characterized in that it comprises a deformation correcting means for correcting the deformation of the recording medium.
The invention according to claim 5 is an image forming unit that forms an image on a recording medium, a medium conveying unit that conveys the recording medium, and a time of the recording medium in the process of conveying the recording medium by the medium conveying unit. Curvature history acquisition means for obtaining information on curvature change due to passage as curvature history information, viscoelastic history acquisition means for obtaining information on viscoelasticity change over time of the recording medium as viscoelastic history information, and curvature history acquisition means Based on the obtained curvature history information and the viscoelastic history information obtained by the viscoelastic history acquisition means, the internal stress of the recording medium that changes over time is integrated, and the internal stress of the recording medium after the time has elapsed. An internal stress distribution calculating means for calculating the distribution, and a deformation curvature calculating means for calculating the deformation curvature of the recording medium that balances the internal stress distribution obtained by the internal stress distribution calculating means. And a deformation correction means for correcting the deformation of the recording medium by applying deformation to the recording medium after the lapse of time so as to reduce the deformation amount of the recording paper having the deformation curvature calculated by the deformation curvature calculation means. An image forming apparatus including the image forming apparatus.
According to a sixth aspect of the present invention, there is provided a computer, a curvature history acquisition unit that obtains information about a change in curvature of a recording medium over time as curvature history information, and information about a change in viscoelasticity of the recording medium over time. Viscoelasticity history acquisition means obtained as described above, curvature history information obtained by the curvature history acquisition means, and viscoelasticity history information obtained by the viscoelasticity history acquisition means, the internal stress of the recording medium that changes over time is obtained. An internal stress distribution calculating means for calculating the internal stress distribution of the recording medium after the lapse of time, and a deformation curvature for calculating the deformation curvature of the recording medium that is balanced with the internal stress distribution obtained by the internal stress distribution calculating means It is a deformation curvature prediction program characterized by functioning as calculation means.
The invention according to claim 7 determines a deformation amount to be applied to the recording medium after the lapse of time so that the computer reduces the deformation amount of the recording paper having the deformation curvature calculated by the deformation curvature calculation means. 7. The deformation curvature prediction program according to claim 6, wherein the deformation curvature prediction program is caused to function as a deformation correction means.

In this specification, “curvature” is a value indicating the degree of curvature of a curved surface, and may be expressed by the reciprocal of the radius of curvature, or may be expressed by a distortion gradient, surface extension, or the like. . Specifically, the “curvature change information” is a curvature given to a reference point on the recording medium (the position is not particularly limited as long as it is a preset point as a reference point). Value. However, since it is a “curvature change with the passage of time”, the value at each time point (each time point with a predetermined resolution) is associated with the passage of time with respect to the curvature of the recording medium that changes momentarily by the conveyance of the recording medium. It shall be comprised. That is, the “curvature history information” is information for specifying the history of the change in curvature of the recording medium over time.
“Viscoelasticity” has both the elastic property that determines the stress generated according to the amount of deformation and the viscous property that stress is generated according to the deformation rate and the generated stress relaxes over time. Refers to the general characteristics of an object. Many “physical models” expressing viscoelasticity are known as “information on changes in viscoelasticity”, and specific examples include a value of a viscosity coefficient and a value of an elastic coefficient in a recording medium. However, since it is a “curvature change with time”, it is assumed that a change with time in the value of the viscosity coefficient and the value of the elastic coefficient can be specified. That is, the “viscoelastic history information” is information for specifying a history of changes in viscoelasticity of the recording medium over time.
The “deformation curvature” refers to the curvature of the recording medium that has been deformed due to the change in shape and viscoelasticity of the recording medium, and specifically includes, for example, the value of the curl curvature of the recording medium.
“Temperature” includes not only the temperature of the recording medium itself but also the ambient temperature around the recording medium that directly affects the temperature.
“Water content” includes not only the water content of the recording medium itself but also the humidity around the recording medium that directly affects the water content.

In the inventions according to claims 1 and 6, it is possible to perform accurate deformation prediction as compared with the case where the deformation curvature of the recording medium is calculated without considering the contribution of both the change in curvature and the change in viscoelasticity.
According to the second aspect of the present invention, it is possible to improve the prediction accuracy of the deformation curvature as compared with the case where the dependency of the viscoelasticity change on the temperature, water content or deformation amount of the recording medium is not taken into consideration.
In the invention according to claim 3, the prediction accuracy of the deformation curvature can be improved as compared with the case where the influence of the weight of the recording medium is not included.
In the inventions according to claims 4, 5, and 7, it is possible to suppress the deformation of the recording medium as compared with the case where the deformation correcting means of this configuration is not used.

  Hereinafter, a deformed curvature predicting device, a medium conveying device, an image forming apparatus, and a deformed curvature predicting program will be described with reference to the drawings.

[First Embodiment]
Here, a modified curvature prediction apparatus and a modified curvature prediction program will be described as the first embodiment of the present invention.

  FIG. 1 is a block diagram illustrating a functional configuration example of the modified curvature prediction apparatus according to the present embodiment. The deformation curvature prediction apparatus is composed of, for example, a simulation apparatus having a computer function, and performs deformation prediction for a recording medium (printing recording paper or the like) whose curvature and viscoelasticity change with time. For this purpose, the deformation curvature prediction apparatus has functions as a curvature history acquisition means 1, a viscoelastic history acquisition means 2, an internal stress distribution calculation means 3, a deformation curvature calculation means 4 and an information holding storage means 5 as shown in the figure. It is prepared for.

  The curvature history acquisition unit 1 obtains information related to a change in curvature over time of the recording medium as curvature history information. Specifically, the “curvature change information” is a curvature given to a reference point on the recording medium (the position is not particularly limited as long as it is a preset point as a reference point). Value. However, since it is a “curvature change with the passage of time”, the value at each time point (each time point with a predetermined resolution) is associated with the passage of time with respect to the curvature of the recording medium that changes momentarily by the conveyance of the recording medium. It shall be comprised. That is, it can be said that the “curvature history information” is information for specifying the history of curvature change of the recording medium over time. Such curvature history information may be obtained by calculation from the shape of the conveyance path through which the recording medium is conveyed, or may be obtained by detecting the shape of the recording medium that is actually conveyed by a sensor or the like. Good. For example, when there is an input by a user or the like of the modified curvature prediction apparatus as a known value, the input value may be used.

  The viscoelastic history acquisition unit 2 obtains information relating to changes in viscoelasticity over time of the recording medium as viscoelastic history information. Many “physical models” expressing viscoelasticity are known as “information on changes in viscoelasticity”, and specific examples include a value of a viscosity coefficient and a value of an elastic coefficient in a recording medium. However, since it is a “curvature change with time”, it is assumed that a change with time in the value of the viscosity coefficient and the value of the elastic coefficient can be specified. This is because when the temperature, moisture content, and deformation of the recording medium change, the viscosity coefficient value and elastic modulus value of the recording medium change before and after the change. This is because the factors such as temperature, water content, and deformation amount (hereinafter referred to as “predetermined factors”) change as the time passes by the conveyance of the recording medium. That is, it can be said that the “viscoelastic history information” is information for specifying a history of changes in viscoelasticity of the recording medium over time.

Such viscoelasticity history information can be obtained by acquiring the above-described predetermined factor value and converting the predetermined factor value based on a preset correspondence. The above-mentioned predetermined factor, the value of the viscosity coefficient of the recording medium, and the value of the elastic coefficient are uniquely associated, and when the value of the predetermined factor changes with time, the viscosity coefficient of the recording medium depends on this. This is because the value of and the modulus of elasticity also change. That is, by acquiring the value of the predetermined factor, viscoelastic history information can be obtained based on the dependency of the viscoelastic change in the recording medium with respect to the value and the amount of change of the value over time.
Note that the predetermined factors acquired here do not have to be all of the temperature, water content, and deformation amount of the recording medium, but may be at least one. Further, a plurality of these (including all cases) may be acquired.
In addition to the temperature of the printing recording medium itself, the “temperature” of the printing recording medium here includes the environmental temperature around the printing recording medium that directly affects the temperature. The “water content” of the printing recording medium includes, in addition to the water content of the printing recording medium itself, the humidity around the printing recording medium that directly affects the water content. Therefore, the environmental temperature or the ambient humidity may be acquired as the temperature or moisture content of the printing recording medium, and the temperature or moisture content of the printing recording medium itself may be derived from the result. Examples of the “deformation amount” of the recording medium for printing include the amount of change in curvature in the recording medium.
The values of these predetermined factors may be acquired by detection with a sensor or the like, or may be acquired using a model formula. Further, for example, when there is an input by a user or the like of the modified curvature prediction apparatus as a known value, the input value may be used.
The “unique correspondence” between the predetermined factor and the value of the viscosity coefficient and the elastic coefficient of the recording medium is determined in advance based on, for example, an empirical rule obtained by a prior experiment or the like. It shall be. This unique correspondence differs depending on the type of recording medium (paper thickness, paper quality, etc.). Therefore, when a plurality of types of recording media are to be processed, it is assumed that a unique correspondence is defined for each type.

  The internal stress distribution calculating means 3 is based on the curvature history information obtained by the curvature history obtaining means 1 and the viscoelastic history information obtained by the viscoelastic history obtaining means 2, and the recording medium that increases or decreases in accordance with the curvature change of the recording medium. The internal stress is integrated to obtain the internal stress distribution of the recording medium after the curvature change. Details of the internal stress accumulation and internal stress distribution calculation methods by the internal stress distribution calculation means 3 will be described later.

  The deformation curvature calculation means 4 calculates the deformation curvature of the recording medium that balances with the internal stress distribution obtained by the internal stress distribution calculation means 3 as the deformation curvature of the recording medium after undergoing a change in curvature. The “deformation curvature” in a recording medium refers to the curvature of the recording medium that has undergone deformation due to a change in shape and viscoelasticity of the recording medium, and specifically includes, for example, the value of the curl curvature of the recording medium. . This deformation curvature is a prediction result of deformation occurring in the recording medium. The details of the calculation of the deformation curvature by the deformation curvature calculation means 4, that is, the method of calculating the deformation curvature of the recording medium that matches the internal stress distribution obtained by the internal stress distribution calculation means 3 will be described later.

  The information holding / storing means 5 holds and stores various information necessary for conversion by the viscoelastic history acquisition means 2, calculation by the internal stress distribution calculation means 3, calculation by the deformation curvature calculation means 4, and the like. is there. The format of the various information is not particularly limited, and may be a table format or an arithmetic expression format. For example, the unambiguous correspondence described above is specified by such various information.

  Each of the means 1 to 5 as described above has a function as a computer including a combination of a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), etc. included in the modified curvature predicting apparatus as a predetermined program. It is realized by executing. In this case, the predetermined program may be provided by being stored in a computer-readable storage medium prior to installation in the deformed curvature prediction apparatus, or distributed via wired or wireless communication means. It may be done. That is, the modified curvature prediction apparatus having the above-described functional configuration can be realized by a modified curvature prediction program that can be installed in the modified curvature prediction apparatus.

  Next, an example of processing operation in the case of predicting the curvature of deformation occurring in the recording medium in the modified curvature prediction apparatus (including the case realized by the modified curvature prediction program) having the above configuration will be described.

Here, as a recording medium to be predicted, a printing paper having a thickness of 98 [μm] used in a copying machine which is one of image forming apparatuses will be described as an example. Note that the paper type is not limited to this, and for example, it is conceivable to select or set from the operation panel of the copying machine.
2A and 2B are explanatory diagrams showing a specific example of viscoelastic characteristics in printing paper, where FIG. 2A shows an example of an elastic coefficient that is one of viscoelastic characteristics, and FIG. 2B shows viscoelastic characteristics. It is a figure which shows the example about the viscosity coefficient which is another one. According to the illustrated example, it can be seen that as the moisture content decreases, that is, the elastic coefficient and the viscosity coefficient both increase, that is, the printing paper tends to become harder.
Such an elastic coefficient and a viscosity coefficient can be obtained by measuring using a well-known viscoelasticity measuring apparatus that is widely used while changing the temperature and water content of the printing paper. Then, when the elastic coefficient and the viscosity coefficient for the printing paper are obtained, the result (for example, mapping data as shown in FIG. 2) is held and stored in the information holding and storing means 5. However, since the elastic coefficient and the viscosity coefficient differ depending on the type of the recording medium, when a plurality of types of recording media are to be processed, it is necessary to measure for each type. In addition, when it is necessary to consider the deformation of printing paper, the amount of deformation and the viscoelastic property are in a non-linear relationship, and it is considered that there is a difference in the viscoelastic property between the case where the amount of deformation is small and the case where the amount of deformation is large. Therefore, measure the viscoelastic characteristics according to each deformation amount, or prepare an arithmetic expression to correct the difference amount so that it can cope with the difference in viscoelastic properties due to deformation. And

  When such a printing paper is used in a copying machine, it is heated to, for example, about 98 [° C.] by a heat fixing device. Then, it is discharged through a conveyance path to the outside of the copying machine. However, the conveyance path often changes the curvature of the printing paper so that the printing paper is curved due to space restrictions in the copying machine.

Therefore, in the present embodiment, in predicting the deformation curvature generated in the printing paper, the curvature of the printing paper (having a specified viscoelastic property) from heating to being discharged through the conveyance path is as follows. Get history information.
FIG. 3 is an explanatory diagram showing a specific example of a change in curvature of the printing paper. For example, as shown in FIG. 3A, when the printing paper 6b heated through the heating roller 6a is guided by the conveyance path 6c, the curvature [1 / m] at a certain point on the printing paper 6b. For example, as shown in FIG. 3 (b), it changes every moment according to the passage of time after passing through the heating roller 6a. The curvature history acquisition unit 1 obtains such a change in curvature, that is, the correspondence between the curvature and time shown in FIG. 3B as curvature history information.
The curvature history information includes, for example, the time required for a certain point on the printing paper 6b to pass the heating path 6c from the heating roller 6a to 0.6 [seconds], 1.0 [seconds], and 1.5 [seconds]. The printing paper is conveyed while changing the speed so that the three values are obtained, and the curvature at the one point at that time is detected by a sensor or the like, or is obtained by performing a simulation calculation. Can be considered. In the example shown in FIG. 3B, the time change of the curvature when one point on the printing paper 6b passes at 1.0 [seconds] is shown.

In addition, after heating the printing paper, the temperature is lowered by natural heat dissipation during the conveyance process. Furthermore, the water content changes with this temperature change.
FIG. 4 is an explanatory diagram showing a specific example of temperature change and moisture content change of the printing paper, (a) is a diagram showing an example of temperature change, and (b) is a diagram showing an example of moisture content change. . The change in temperature and moisture content of the printing paper do not depend on the difference in the conveyance speed of the printing paper, and can be regarded as the same at any conveyance speed.
The correspondence relationship between the temperature change and the moisture content change and the passage of time is specified based on the actual measurement result or the calculation result based on the given condition, similarly to the viscoelastic property of the printing paper. That's fine. The result is held and stored in the information holding and storing means 5.

Thereafter, the viscoelastic history acquisition unit 2 acquires values of predetermined factors such as the temperature, water content, and deformation amount of the printing paper.
The temperature value may be obtained by directly measuring the temperature of the printing paper itself that changes every moment in the conveyance process or the ambient temperature around it, but the temperature change and time stored in the information holding storage means 5 It is conceivable that each temperature is obtained by estimating each temperature from the temperature of the printing paper itself immediately after heating or the surrounding ambient temperature based on information on the correspondence relationship with the process.
The moisture content value may be obtained by directly measuring the moisture content of the printing paper itself, which changes from moment to moment in the conveying process, or the moisture content of the printing paper may be derived from the surrounding environmental humidity. Based on the information on the correspondence between the change in water content and the passage of time that is stored and stored in the information storage and storage means 5, the water content of the printing paper itself immediately after heating or the surrounding environmental humidity It can be obtained by estimating the amount of water.
The amount of deformation of the printing paper can be obtained by using the curvature history information obtained by the curvature history acquisition unit 1. That is, based on the curvature history information held and stored in the information holding and storing means 5, the curvature of a point on the printing paper that changes from moment to moment immediately after heating can be known, so the value of the curvature is printed. The amount of deformation of the paper.

When the value of the predetermined factor is acquired, the viscoelasticity history acquisition unit 2 acquires the acquisition result and the viscoelastic characteristics of the printing paper held and stored in the information holding storage unit 5, that is, the predetermined factor and the viscosity of the printing paper. Based on the unambiguous correspondence between the elastic characteristics and the viscoelasticity history information, the value of the viscosity coefficient and the value of the elastic coefficient of the printing paper that change from moment to moment immediately after heating are obtained.
Note that the viscoelastic history information is not necessarily obtained based on the value of the predetermined factor described above, and may be obtained based on a factor other than the temperature, the water content, or the deformation amount. Other factors include, for example, those in which viscoelastic properties such as external force acting on the printing paper and chemical species concentration have dependency relationships.

  After the curvature history acquisition means 1 obtains the curvature history information, the curvature of the printing paper can be known from the curvature history information, so the internal stress distribution calculation means 3 calculates the amount of distortion generated inside the printing paper from the curvature. . At this time, the printing paper is bent, so that the stretched side is pulled, and the compressed side is compressed, and the bending radius of curvature, the amount of extension, and the amount of contraction are in a linear relationship. Then, the distortion amount is calculated using a known calculation method.

Then, the internal stress distribution calculating unit 3 calculates the internal stress in the printing paper from the amount of strain generated in the printing paper and the viscoelastic characteristics of the printing paper, that is, the viscoelastic history information acquired by the viscoelastic history acquisition unit 2. Calculate the stress.
FIG. 5 is an explanatory diagram showing an example of the concept of calculation of internal stress. Since printing paper has elasticity and viscosity, the internal stress in the printing paper can be calculated by considering the configuration of a spring and a dashpot as shown in the figure. That is, in the configuration of the example called the Maxwell model, the spring representing the hook elasticity and the dashpot representing the Newtonian viscosity are connected in series. Is the sum of the amount of strain determined by Hooke's law and the amount of strain determined by Newton's viscosity law from the viscosity coefficient η of the dashpot. Since these are in series, the stresses generated in the spring and the dashpot are equal, and if the stress relaxation in the dashpot is reflected by time differentiation, the internal stress σ is calculated from the values of strain ε, elastic constant E and viscosity coefficient η. Can be calculated.

However, in the Maxwell model, a spring indicates that a stress proportional to the amount of strain is generated, and a dashpot generates a force proportional to the rate of deformation or the magnitude of the stress is proportional to the magnitude of the deformation. Represents the property of relaxing with. This means that when the curvature (deformation amount) changes from moment to moment, and the amount of strain also increases or decreases with time, the internal stress at each time is not only the amount of strain at that moment, It means that it depends on the time history of the past distortion amount.
Therefore, the internal stress distribution calculation means 3 integrates the amount of increase / decrease in internal stress due to the increase / decrease in the amount of distortion of the printing paper with the passage of time after heating and the amount of relaxation of the internal stress with respect to time when calculating the internal stress in the printing paper. Do the calculation that goes. Thereby, the internal stress distribution calculating means 3 obtains the internal stress distribution of the printing paper after the printing paper has undergone the curvature change with the passage of time after heating, that is, the distribution of the stress inside the paper after discharging. Become.
In general, the curvature varies depending on the in-plane position of the printing paper, so the three-dimensional distribution is in the in-plane direction and the thickness direction. In this case, the curvature is approximated to be uniform in the thickness direction. Only the distribution of

  When the internal stress distribution is obtained by the procedure as described above, even if the deformation amount (curvature) of the printing paper after discharging is the same, the change in curvature up to that point (for example, see FIG. 3B) and viscosity When the elastic changes are different without matching, the internal stress distributions are also different without matching.

After obtaining the internal stress distribution of the printing paper in this way, the deformation curvature calculating means 4 obtains the deformation curvature of the printing paper that matches the internal stress distribution. The balanced state may be specified by using a known technique using beam stress calculation or the like, and thus detailed description thereof is omitted here.
FIG. 6 is an explanatory diagram showing a specific example of the internal stress distribution and the deformation curvature commensurate with the internal stress distribution. For example, when an internal stress distribution as shown in FIG. 6A is obtained, a stress balance state is established inside the printing paper by giving a deformation curvature as shown in FIG. 6B. It will be.
Then, the deformation curvature calculating means 4 calculates the deformation curvature that balances with the internal stress as the deformation curvature in the printing paper after undergoing the curvature change.

  FIG. 7 is an explanatory diagram showing a specific example of the calculation result and the measurement result of the deformation curvature. In the illustrated example, when a certain point on the printing paper 6b passes through the conveyance path 6c from the heating roller 6a is 0.6 [seconds], 1.0 [seconds], and 1.5 [seconds]. For each of these (see FIG. 3A), the calculation result of deformation curvature (see “calculation result” in the figure) and the actual measurement result (see “experiment result” in the figure) are shown. According to this example, it can be seen that a result close to the experimental result is obtained as the calculation result.

When determining the deformation curvature of a printing paper that balances the internal stress distribution of the printing paper, if there is a possibility that the printing paper bends due to its own weight, the balance condition may include the influence of gravity (the weight of the printing paper). It is done.
FIG. 8 is an explanatory diagram showing a specific example of the internal stress distribution and the deformation curvature that balances the internal stress distribution when the influence of gravity is included in the balance condition. For example, when an internal stress distribution causing deformation as shown in FIG. 8 (a) is obtained, the beam is calculated in consideration of conditions such as gravity and contact acting on the printing paper, whereby FIG. The stress balanced state is established by the shape given the deformation curvature as shown in b). Further, for example, when an internal stress distribution causing deformation as shown in FIG. 8C is obtained, the beam is calculated by taking into account conditions such as gravity and contact acting on the printing paper. The stress balance state is established by the shape given the deformation curvature as shown in FIG.

[Second Embodiment]
Next, as a second embodiment of the present invention, a medium transport device, an image forming apparatus, and a deformation curvature prediction program will be described.

  FIG. 9 is a block diagram illustrating a functional configuration example of the image forming apparatus according to the present embodiment. The image forming apparatus 10 includes, for example, a copying machine, a printer apparatus, a facsimile apparatus, or a combination of these functions, and prints out an image on a recording medium. For this purpose, the image forming apparatus 10 is configured to have functions as an image forming unit 11 and a medium conveying unit 12 as shown in the figure.

  The image forming unit 11 forms an image on a recording medium. Image formation is performed using, for example, electrophotographic technology. The image forming means 11 in the present embodiment has a heat fixing device for fixing the formed image on the medium, and the heat fixing device heats the recording medium.

  The medium conveying unit 12 conveys the recording medium, and examples thereof include a conveying roller that moves the recording medium and a conveying guide that guides the movement. Since the space in the image forming apparatus 10 is limited, it is assumed that the recording medium transport path by the medium transport unit 12 includes a portion that gives a curvature that curves the recording medium. .

  By the way, the recording medium to be transported by the medium transporting unit 12 includes a recording medium after image formation by the image forming unit 11, that is, a recording medium heated by a heat fixing device. Therefore, the temperature of the recording medium conveyed by the medium conveying means 12 is lowered by natural heat dissipation during the conveyance process, so that the viscoelastic characteristics change with time. Further, since the temperature, humidity, and the like of the environment where the image forming apparatus 10 is installed are not always constant and fluctuate, the viscoelastic characteristics of the recording medium may change over time due to the influence.

  Therefore, the image forming apparatus according to the present embodiment includes the medium deformation curvature prediction unit 12a and the deformation correction unit 12b. The medium conveyance unit 12, the medium deformation curvature prediction unit 12a, and the deformation correction unit 12b It corresponds to a transport device.

  The medium deformation curvature predicting unit 12a predicts the deformation curvature of the recording medium conveyed by the medium conveying unit 12. The prediction is performed as described in the first embodiment. That is, the medium deformation curvature prediction unit 12a of the present embodiment has the same functional configuration as the deformation curvature prediction apparatus described in the first embodiment.

  The deformation correction unit 12b applies deformation to the recording medium to be transported by the medium transport unit 12 so as to reduce the deformation amount specified from the deformation curvature calculated by the medium deformation curvature prediction unit 12a. Therefore, the deformation correcting unit 12b is configured to have a mechanism for deforming the recording medium and a function for controlling the operation of the mechanism.

  FIG. 10 is an explanatory diagram showing a configuration example of a mechanism for deforming the recording medium. As a mechanism for deforming the recording medium, for example, a guide plate 6d constituting a part of the transport path, and a drive source (not shown) for correcting the shape of the transport path by moving the position of the guide plate 6d. It is conceivable to have More specifically, for example, as shown in FIGS. 10A and 10B, the position of the guide plate 6d is moved so that the distance d from the heating roller 6a to the guide plate 6d can be changed. As shown in FIGS. 10C and 10D, it is conceivable to move the position of the guide plate 6d so as to vary the angle θ of the guide plate 6d with respect to the transport path.

  Of the means 11, 12, 12a and 12b as described above, the control function in the medium deformation curvature prediction means 12a and the deformation correction means 12b is a predetermined function as a computer comprising a combination of CPU, RAM, ROM and the like. It is realized by executing a program. In this case, the predetermined program may be provided by being stored in a computer-readable storage medium prior to installation in the image forming apparatus or a similar apparatus, or a wired or wireless communication means. It may be delivered via. That is, the functional configuration for controlling the medium conveyance in the medium conveyance unit 12 can be realized by a medium conveyance control program that causes a computer to function as a medium conveyance device.

  Subsequently, in the processing operation example in the image forming apparatus 10 having the above-described configuration, particularly the processing operation example in the medium transport unit 12, an example in which the recording medium is the printing paper described in the first embodiment is described. Will be described.

  In the image forming apparatus 10, when the printing paper is conveyed using the medium conveying unit 12, the shape of the sheet conveying path (curvature change) by the medium conveying unit 12, the temperature of the printing paper being conveyed, and the change in water content Based on these predetermined elements, the deformation curvature predicting means 12a predicts the deformation curvature of the printing paper after conveyance in the same procedure as in the first embodiment described above.

  After obtaining the deformation curvature prediction result, the deformation correction unit 12b deforms the printing paper to be conveyed by the medium conveyance unit 12 based on the prediction result. At this time, the deformation correcting means 12b moves the position of the guide plate 6d to deform the print paper, and obtains the final curvature of the print paper after moving the guide plate 6d, and further if necessary. Then, the curvature of the guide plate 6d is calculated by changing the position of the guide plate 6d, and the amount of movement of the guide plate 6d with the smallest curvature is obtained. Then, the drive source of the guide plate 6d is operated so that the moving amount of the guide plate 6d matches the obtained value. As a result, the deformation correcting unit 12b deforms the printing paper to be conveyed by the medium conveying unit 12 so as to reduce the deformation amount specified from the deformation curvature calculated by the medium deformation curvature predicting unit 12a. Become.

  FIG. 11 is an explanatory diagram illustrating a specific example of the deformation curvature of the printing paper after the deformation that reduces the deformation amount is given to the printing paper. In the illustrated example, when the image forming apparatus 10 is used in three different environments, the curvature of the printing paper before correction (before imparting deformation) is the value of “before correction” in the figure, As a result of the deformation correcting means 12b moving the guide plate 6d to correct the deformation of the printing paper, the curvature of the printing paper after the correction (after the deformation is applied) has a value of “after correction” in the figure. Is shown. Note that the curvature value predicted by the calculation at this time is indicated by “calculation result” in the figure.

  As described above, the deformation correction unit 12b gives the print sheet a deformation that reduces the deformation amount based on the deformation prediction result of the print sheet by the medium deformation curvature prediction unit 12a, thereby suppressing the occurrence of the deformation in the print sheet. It is.

In the above-described first and second embodiments, preferred specific examples of the present invention have been described. However, the present invention is not limited to the contents, and may be appropriately changed without departing from the gist thereof. Is possible.
For example, in the above description, printing paper is given as a specific example of the recording medium. However, the present invention is not limited to this, and can be applied to other recording media in exactly the same manner. Of course. In the above description, the case where the deformation is a curl having a curvature along one direction is taken as an example, but the deformation curvature is also applied to a three-dimensional deformation having a curvature in a plurality of directions by applying the present invention. It is possible to predict.

It is a block diagram which shows the function structural example of the deformation | transformation curvature prediction apparatus which concerns on 1st Embodiment. It is explanatory drawing which shows a specific example of the viscoelastic characteristic in printing paper, (a) is a figure which shows the example about the elastic coefficient which is one of the viscoelastic characteristics, (b) is another one of the viscoelastic characteristics. It is a figure which shows the example about the viscosity coefficient which is. It is explanatory drawing which shows a specific example of the curvature change of printing paper, (a) is a figure which shows the example about the conveyance path | route which gives a curvature change, (b) is a figure which shows the example of the curvature change by progress of time. It is explanatory drawing which shows a specific example of the temperature change and moisture content change of a printing paper, (a) is a figure which shows the example of a temperature change, (b) is a figure which shows the example of a moisture content change. It is explanatory drawing which shows an example of the concept of the calculation of the internal stress performed in consideration of a viscoelastic characteristic. It is explanatory drawing which shows a specific example of internal stress distribution and the deformation | transformation curvature which balances this, (a) is a figure which shows the example of internal stress distribution, (b) is a figure which shows the example of the deformation curvature which balances this. . It is explanatory drawing which shows a specific example about the calculation result and measurement result of a deformation | transformation curvature. It is explanatory drawing which shows a specific example of internal stress distribution and the deformation curvature which balances this in the case where the influence of gravity is included in the condition of balance, (a) is a figure which shows the example of internal stress distribution, (b) FIG. 7 is a diagram showing an example of a deformation curvature commensurate with this, (c) is a diagram showing another example of an internal stress distribution, and (d) is a diagram showing an example of a deformation curvature commensurate with this. 6 is a block diagram illustrating a functional configuration example of an image forming apparatus according to a second embodiment. FIG. It is explanatory drawing which shows the structural example of the mechanism which gives a deformation | transformation to a recording medium, (a) And (b) is a figure which shows the example, (c) And (d) is a figure which shows another example. It is explanatory drawing which shows the specific example about the deformation | transformation curvature in the said recording medium after giving the deformation | transformation which reduces a deformation amount to a recording medium.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Curvature history acquisition means, 2 ... Viscoelasticity history acquisition means, 3 ... Internal stress distribution calculation means, 4 ... Deformation curvature calculation means, 5 ... Information holding storage means, 10 ... Image forming apparatus, 11 ... Image formation means, 12 ... Medium conveying means, 12a ... Medium deformation curvature predicting means, 12b ... Deformation correcting means

Claims (7)

Curvature history acquisition means for obtaining information on curvature change over time of the recording medium as curvature history information;
Viscoelasticity history acquisition means for obtaining information on viscoelasticity change over time of the recording medium as viscoelasticity history information;
Based on the curvature history information obtained by the curvature history acquisition means and the viscoelastic history information obtained by the viscoelastic history acquisition means, the internal stress of the recording medium that changes over time is integrated, and after the time has elapsed. Internal stress distribution calculating means for calculating internal stress distribution of the recording medium;
A deformation curvature prediction apparatus comprising: a deformation curvature calculation means for calculating a deformation curvature of a recording medium that balances with the internal stress distribution obtained by the internal stress distribution calculation means. The viscoelasticity history acquisition means is based on the dependence relationship of the viscoelasticity change of the recording medium with respect to at least one of the temperature, water content, or deformation amount of the recording medium, and the amount of change over time. The deformation curvature prediction apparatus according to claim 1, wherein viscoelastic history information is obtained. The deformed curvature predicting apparatus according to claim 1, wherein the deformed curvature calculating means includes an influence of the weight of the recording medium in a balance condition. Medium conveying means for conveying the recording medium;
Curvature history acquisition means for obtaining, as curvature history information, information related to curvature change over time of the recording medium in the course of transporting the recording medium by the medium transport means;
Viscoelasticity history acquisition means for obtaining information on viscoelasticity change over time of the recording medium as viscoelasticity history information;
Based on the curvature history information obtained by the curvature history acquisition means and the viscoelastic history information obtained by the viscoelastic history acquisition means, the internal stress of the recording medium that changes over time is integrated, and after the time has elapsed. An internal stress distribution calculating means for calculating an internal stress distribution of the recording medium;
Deformation curvature calculating means for calculating a deformation curvature of the recording medium that balances with the internal stress distribution obtained by the internal stress distribution calculating means;
Deformation correction means for applying deformation to the recording medium after the lapse of time so as to reduce the deformation amount of the recording paper having the deformation curvature calculated by the deformation curvature calculation means, and correcting the deformation of the recording medium. A medium conveying apparatus characterized by the above. Image forming means for forming an image on a recording medium;
Medium conveying means for conveying the recording medium;
Curvature history acquisition means for obtaining, as curvature history information, information related to curvature change over time of the recording medium in the course of transporting the recording medium by the medium transport means;
Viscoelasticity history acquisition means for obtaining information on viscoelasticity change over time of the recording medium as viscoelasticity history information;
Based on the curvature history information obtained by the curvature history acquisition means and the viscoelastic history information obtained by the viscoelastic history acquisition means, the internal stress of the recording medium that changes over time is integrated, and after the time has elapsed. Internal stress distribution calculating means for calculating internal stress distribution of the recording medium;
Deformation curvature calculating means for calculating a deformation curvature of the recording medium that balances with the internal stress distribution obtained by the internal stress distribution calculating means;
Deformation correction means for applying deformation to the recording medium after the lapse of time so as to reduce the deformation amount of the recording paper having the deformation curvature calculated by the deformation curvature calculation means, and correcting the deformation of the recording medium. An image forming apparatus. Computer
Curvature history acquisition means for obtaining information on curvature change over time of the recording medium as curvature history information;
Viscoelasticity history acquisition means for obtaining information on viscoelasticity change over time of the recording medium as viscoelasticity history information;
Based on the curvature history information obtained by the curvature history acquisition means and the viscoelastic history information obtained by the viscoelastic history acquisition means, the internal stress of the recording medium that changes over time is integrated, and after the time has elapsed. Internal stress distribution calculating means for calculating internal stress distribution of the recording medium;
A deformation curvature prediction program that functions as deformation curvature calculation means for calculating a deformation curvature of a recording medium that balances the internal stress distribution obtained by the internal stress distribution calculation means. The computer,
The deformation curvature calculating means functions as a deformation correction means for determining a deformation amount to be applied to the recording medium after the lapse of time so as to reduce the deformation amount of the recording paper having the deformation curvature calculated by the deformation curvature calculating means. The deformation curvature prediction program according to claim 6.

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