Patent Application
20240198697
The present disclosure relates to a printing apparatus including a fixing unit configured to fix a printed image with heat and a control method of the same.
Among printing apparatuses configured to form an image by applying ink to a printing medium, there is a printing apparatus configured to fix the image by performing a heating process on the printing medium. In such a heating process, increasing an amount of heat applied to the printing medium promotes the evaporation of a solvent included in the ink, melting of a resin, and film formation, and the image tends to be fixed more surely in a shorter time.
However, depending on the heating temperature, there may occur a case where a molecular structure of the printing medium changes and the printing medium is deformed. Accordingly, it is preferable to adjust the amount of heating to a level at which no deformation of the printing medium occurs and preferable fixation is achieved. However, such a preferable amount of heating depends on a material of the printing medium. Moreover, the heat capacity of the printing medium varies depending on the thickness or size of the printing medium, even in the case of the same material. Accordingly, the printing apparatus configured to perform heating fixation is required to optimize the heating process depending on the printing medium to be used, that is to set an optimal heating temperature for each type of printing medium.
Japanese Patent Laid-Open No. 2017-140782 (hereinafter, referred to as Literature 1) discloses a technique as follows. A deformation amount of a printing medium is measured, whether the measured deformation amount has exceeded a deformation amount threshold defined in advance is determined. Then, the fixation temperature is determined to be a temperature lower than a glass transition point at which a molecular structure of the printing medium changes.
Among printing media used in the field of sign display, there is a printing medium with a glass transition point lower than a heating temperature range of a fixing unit. In Literature 1, a fixed value is used as a deformation amount threshold. Accordingly, the printing medium with the low glass transition point is determined as a printing medium to which an image cannot be fixed.
A printing apparatus of the present disclosure includes: a fixing unit configured to fix an image onto a printing medium by heating the printing medium on which the image is printed; a measuring unit configured to measure a length of the printing medium after heating of the printing medium in the fixing unit; a deriving unit configured to derive a characteristic of a deformation amount of the printing medium with respect to temperature based on the measured length; a receiving unit configured to receive a specification of a deformation amount threshold; and a determining unit configured to determine a fixation temperature in fixation of the image onto the printing medium by the fixing unit, based on the derived characteristic and the received deformation amount threshold.
Further features of the present disclosure will become apparent from the following description of exemplary embodiments with reference to the attached drawings.
Embodiments of the present disclosure are described below in detail with reference to the attached drawings. Note that the following embodiments do not limit the matters of the present disclosure, and not all of the combinations of features described in the following embodiments are necessarily essential for the solving means of the present disclosure. Note that the same constituent elements are denoted by the same reference numerals.
The printing apparatus 100 includes an input/output unit 109 in an upper portion. The input/output unit 109 is formed of, for example, an operation panel. Specifically, the input/output unit 109 includes a display, and an ink remaining amount, candidates of a type of printing medium, and the like are displayed on the display. The user can select the type of the printing medium and perform setting of printing by operating keys on the operation panel.
The carriage 101 includes an optical sensor 201 (
The printing medium 105 such as a roll paper is conveyed by a not-illustrated conveyance roller in the Y direction on a platen 106. The carriage 101 performs a printing operation by ejecting ink droplets from the print head 102 while moving in the X direction above the printing medium 105 conveyed onto the platen 106 by the conveyance roller. In the case where the carriage 101 moves to an end of a printing region on the printing medium 105, the conveyance roller conveys the printing medium 105 by a certain amount, and moves the printing medium 105 to such a position that the print head 102 can perform printing on a region to be subjected to next print scanning. The above operation is repeatedly performed to print an image. The ink used in image printing in the present embodiment is a latex ink. Applying heat to the ink causes a water content to evaporate and causes a latex resin to melt and mix with a pigment, and a film is formed and cured on the printing medium surface. In the case where a general aqueous ink is used, the printing medium needs to have an ink receiving layer for catching the ink and suppressing bleeding. Meanwhile, the latex printer can perform printing on a printing medium having no ink receiving layer. In the present embodiment, the printing medium 105 subjected to printing is conveyed to a fixing unit 108. The fixing unit 108 is arranged downstream, in the Y direction (conveyance direction), of the printing region in which the print head 102 performs the printing. Heat is applied to the conveyed printing medium 105 in the fixing unit 108, and is discharged from the fixing unit 108 in a state (finished state) where the ink is cured and fixed onto the printing medium.
In this section, a printing medium used in the field of sign display is briefly described. In a production step of a polymer film to be the printing medium, a process referred to as drawing in which the film is stretched in a certain direction is generally performed. In this case, a characteristic crystallization referred to as orientated crystallization occurs due to aligning of molecules of the film in a certain direction, and a unique structure referred to as fiber structure is formed. Such a fiber structure is in a state where entropy is suppressed to a low level at normal temperature. However, in the case where the temperature exceeds a temperature referred to as glass transition point, the entropy increases, and amorphous molecules become movable. As a result, contraction due to entropic elasticity (rubber elasticity) occurs, and this causes deformation and stiffness change of the film. In a printing medium with a glass transition point lower than a heating temperature range of the fixing unit 108, deformation tends to occur even in the case where the heating temperature is set to a minimum temperature. Accordingly, in a method of determining a fixation temperature from the glass transition point of the printing medium, the printing medium to be used is limited to a printing medium whose glass transition point is included in a heating temperature range of the fixing unit 108. In the present embodiment, description is given of an example in which an optimal fixation temperature can be determined also for a printing medium with a glass transition point lower than the heating temperature range of the fixing unit 108, the optimal fixation temperature being temperature at which deformation is suppressed to a desired deformation amount. Details are described later.
The second LED 302 is a light source having an angle of irradiation of 60° in the Z direction with respect to the surface (measurement surface) of the printing medium 105. The first photodiode 304 receives reflection of light emitted from the second LED 302 and reflected on the printing medium 105, at an angle of 60° in the Z direction. Specifically, the second LED 302 and the first photodiode 304 form an optical system in which an angle of light emission and an angle of light reception are equal and that detects a so-called specular reflection component of the reflected light from the printing medium 105. Although the angle is not limited to 60° , the angle of 60° is preferable in consideration of the size of the optical sensor 201 and an SN ratio of the received light.
The third LED 303 is a light source having an angle of irradiation of a normal line)(90° with respect to the surface (measurement surface) of the printing medium 105. The second photodiode 305 and the third photodiode 306 receive reflection of light emitted from the third LED 303 and reflected on the printing medium 105. Light receiving amounts of the respective second photodiode 305 and third photodiode 306 change depending on a distance between the optical sensor 201 and the printing medium 105. The distance between the optical sensor 201 and the printing medium 105 can be thereby measured.
Although an example in which the optical sensor 201 is installed in the carriage 101 is described in the present embodiment, other configurations may be employed. For example, the optical sensor may be installed by being fixed to the printing apparatus 100. Alternatively, there may be employed a configuration in which a measurement device for measuring characteristics of the printing medium that is separate from the printing apparatus 100 is used, and the characteristics measured by the measurement device are transmitted to the printing apparatus.
An axial-flow air blow fan 402, which takes in outside air and blows the air, and a heater 403, which heats the air blown from the air blow fan 402 to turn the air to dry air, are provided in a chamber 401. The dry air blown from an opening portion of the chamber 401 contributes to the fixation of the ink. The fixation temperature of the heater 403 can be changed, and is determined to be a heating temperature optimal for the target printing medium 105 based on a flowchart of determining the fixation temperature to be described later. The heater 403 includes a temperature sensor 404. Temperature feedback from the temperature sensor 404 enables more stable heater temperature control. Note that, although a non-contact ink fixing configuration using dry air and achieved by the combination of the air blow fan 402 and the heater 403 is employed in the present example, a configuration using a contact heater or a radiant heater may be employed.
An interface (I/F) circuit 510 connects the printing apparatus 100 and an external network such as a LAN to each other. The printing apparatus 100 exchanges various jobs, data, and the like with an external apparatus such as a host computer by using the I/F circuit 510.
The input/output unit 109 includes an input unit and an output unit. The input unit receives an instruction of power on, an instruction of print execution, and an instruction of setting various functions from the user. The output unit displays various pieces of apparatus information such as a power saving mode and a setting screen of various functions that can be executed by the printing apparatus 100. In the present embodiment, the input/output unit 109 is an operation panel included in the printing apparatus 100. The input/output unit 109 is connected to a system bus 519 via an input/output control circuit 505 to be capable of exchanging data with the system bus 519. In the present embodiment, the CPU 501 performs notification control of information of the output unit.
Note that the input unit may be a keyboard of an external host computer and be capable of receiving instructions of the user from the external host computer. The output unit may be an LED display, an LCD display, or a display connected to the host apparatus. Moreover, in the case where the input/output unit is a touch panel, the input/output unit can receive instructions from the user through software keys. Moreover, the input/output unit 109 may be formed of a speaker and a microphone and be configured such that an input from the user is a voice input and notification to the user is a voice output.
In the case where the measurement by the optical sensor 201 is to be executed, the CPU 501 drives an LED control circuit 507 to perform control such that a predetermined LED in the optical sensor 201 is turned on. Each of the photodiodes in the optical sensor 201 outputs a signal corresponding to the received light, an A/D conversion circuit 508 converts the signal to a digital signal, and the digital signal is temporarily saved in the RAM 503. Data to be saved also during power off of the printing apparatus 100 is stored in the EEPROM 504.
A print head control circuit 511 supplies a drive signal corresponding to print data to a nozzle drive circuit including a selector and a switch mounted in the print head 102, and performs control of a printing operation of the print head 102 such as drive order of nozzles. For example, in the case where print target data is transmitted from the outside to the I/F circuit 510, the print target data is temporarily saved in the RAM 503. Then, the print head control circuit 511 drives the print head 102 based on print data obtained by converting the print target data to print data for printing. In this case, a line feed (LF) motor drive circuit 512 drives an LF motor 513 based on a bandwidth of the print data or the like, and rotates the conveyance roller connected to the LF motor 513 to convey the printing medium 105. A carriage (CR) motor drive circuit 514 drives a carriage (CR) motor 515 to perform scanning of the carriage 101 via the carriage belt 103.
Data sent from the I/F circuit 510 includes not only the print target data but also data on contents set in a printer driver. Moreover, for example, the print target data is received from the outside via the I/F circuit 510 and stored in a storage unit such as the RAM 503, or is stored in advance in a storage unit such as a hard disk drive in some cases. The CPU 501 reads image data from the storage unit and controls an image processing circuit 509 to perform conversion (binarization process) of the image data to the print data for using the print head 102. The image processing circuit 509 executes various image processes such as color space conversion, HV conversion, gamma correction, and rotation of an image, in addition to the binarization process.
A fan drive circuit 516 controls the air blow amount from the air blow fan 402 by controlling the number of revolutions of the air blow fan 402. A heater drive circuit 517 performs temperature control of the heater 403 based on heating temperature setting information from the CPU 501 and the temperature feedback from the temperature sensor 404 installed near the heater 403. A timer 518 measures heating time by the fixing unit.
As described above, the printing medium has such a characteristic that the glass transition point varies depending on the type of the printing medium, and thus a deformation amount with respect to temperature varies. Accordingly, in the case where the user uses an unknown printing medium, the optimal fixation temperature needs to be determined in consideration of the deformation amount and the fixation temperature. In the present embodiment, description is given of an example in which the optimal fixation temperature is automatically derived by the process illustrated in
In S601, the CPU 501 prints a pattern for length measurement on the set printing medium 105.
In S602, after the printing of the patterns, the CPU 501 measures the inter-pattern length before heating (first temperature) by using the optical sensor 201. In the measurement of the length, light is emitted from the first LED 301 at an angle of 90° in the Z direction, and reflected light from the patterns on the printing medium 105 is received at an angle of 45° in the Z direction to detect a diffuse-reflection component. The CPU 501 detects the first pattern P1 on the downstream side and the second pattern P2 on the upstream side with the optical sensor 201 while conveying the printing medium 105 in the conveyance direction (Y direction). Then, the CPU 501 obtains a conveyance amount in a period from the detection of the first pattern P1 on the downstream side to the detection of the second pattern P2 on the upstream side, from a difference between encoder positions at time points of detection of the respective patterns. Then, the CPU 501 measures the inter-pattern length from the obtained conveyance amount.
In the case where the measurement of the length before the heating is completed, in S603, the CPU 501 performs a heating process on the printing medium 105 at a predetermined temperature (second temperature). In the case where the fixation is completed by the heating process, in S604, the CPU 501 conveys the printing medium in the -Y direction to a position directly below the optical sensor 201, and measures the inter-pattern length as in the measurement before the heating. Specifically, the CPU 501 measures the inter-pattern length after the heating (second temperature). Next, in S605, the CPU 501 calculates a deformation amount of the printing medium 105 after the heating with respect to the printing medium 105 before the heating, with the inter-pattern length before the heating being a reference.
Next, in S606, the CPU 501 determines whether the heating process is completed at two temperatures. In the above-mentioned example, the heating process is completed at one temperature that is the second temperature. Accordingly, the determination result is NO, and the CPU 501 proceeds to S607. In S607, the CPU 501 increases the heating temperature to a third temperature. Then, the CPU 501 performs the processes of S601 and beyond again. In this case, the heating process is performed at the third temperature in S603. Specifically, in second S604, the inter-pattern length after the heating at the third temperature is measured, and in second S606, a deformation amount at the third temperature is calculated. Then, in S606, determination of whether the heating process is completed at two temperatures is performed again. In the case where the heating process is completed at two temperatures, the CPU 501 proceeds to S608.
In the processes up to this point, the inter-pattern lengths at three temperatures are measured. Specifically, the inter-pattern lengths at the temperature (first temperature) before the heating and at the two temperatures (second temperature and third temperature) after the heating are measured. Accordingly, the deformation amounts of the printing medium 105 at a total of three temperatures including the first temperature, the second temperature, and the third temperature are calculated. Note that, assuming that the deformation amount (S602) at the first temperature is referred to as a first deformation amount for the sake of convenience, a second deformation amount (first S605) from the first temperature to the second temperature and a third deformation amount (second S605) from the first temperature to the third temperature are calculated.
Note that, in the present embodiment, description is given assuming that the inter-pattern length of the patterns printed on the printing medium 105 is 200 mm in the example of
Next, in S608, the CPU 501 calculates a deformation characteristic of the printing medium 105 with respect to temperature based on the deformation amounts at the three temperatures calculated up to this point.
In Formula 1, ΔL means the deformation amount and ΔT means an amount of change in temperature. Moreover, the coefficient A represents deformability due to temperature, and the coefficient q and the coefficient K represent the magnitude of the deformation amount due to temperature. Accordingly, the deformation characteristic of each type of printing medium with respect to temperature can be defined by using the values of the coefficients A, q, and K.
In the present embodiment, in the case where the sub-flow of S608 is started, in S614, the CPU 501 first sets K=80. This setting is made due to the following reason. The magnitude of the deformation amount is determined by a combination of the coefficient q and the coefficient K. Due to this relationship, the deformation characteristic of the printing medium 105 with respect to temperature can be calculated by using the coefficients A and q even in the case where the coefficient K is fixed to a certain value. As illustrated in S616, S616, S168, and S619, the CPU 501 executes a flow of a double loop in which an evaluation function R of Formula 2 is calculated in ranges of A=0 to 20 and q =−1 to 0. In S615, the CPU 501 changes the value of A in the range of A=0 to 20, and in S616, changes the value of q in the range q =−1 to 0 in the changing of the value of A to calculate the evaluation function R in S617. Specifically, the CPU 501 repeats the calculation of the evaluation function R in the ranges of A=0 to 20 and q =−1 to 0.
The evaluation function R is a root means square (RMS) of a difference between the calculation value AL of the deformation amount of Formula 1 and the deformation amount ΔL′ calculated from the inter-pattern length in S605. The larger the value of R is, the larger the error between the deformation amount of Formula 1 and the deformation amount in S605 is. In S618 and S619, the CPU 501 calculates the evaluation function R in the range of q=−1 to 0 and A=0 to 20, and in S620, determines each of the coefficients A and q at which R is the smallest as an optimal solution. In Formula 2, the values of the above-mentioned first deformation amount (ΔL′0), the second deformation amount (ΔL′1) calculated in S605, and the third deformation amount (ΔL′2) are put into ΔL′K. Note that the first deformation amount (ΔL′0) is 0. As described above, in Formula 2, the values obtained from Formula 1 by fixing the coefficient K to a certain value and changing the coefficient A and the coefficient q are put into ΔLK. Note that 0 is put into ΔT in case of ΔL0, 60 is put into ΔT in case of ΔL1, and 80 is put into ΔT in case of ΔL2., in the example explained above. In the case where the coefficient A and the coefficient q are obtained in S620, the coefficient K is also obtained.
In the case where the coefficients A, q, and K are determined as described above, the deformation amount ΔL with respect to the temperature change AT can be calculated according to Formula 1 (ΔL=q.(ΔT/K){circumflex over ( )}A). Accordingly, it is possible to calculate the deformation characteristic of the used printing medium with respect to temperature by performing the operation of S614 to S620.
Note that the process of calculating the deformation characteristic of the printing medium with respect to temperature described above is merely an example, and the process is not limited to this example. The method of deriving the deformation characteristic of the printing medium with respect to temperature and the initial values and the ranges in the deriving are not limited to those in the above example. The deformation characteristic may be derived by using a different formula or by applying a different algorithm. In any case, it is only necessary to find out the deformation characteristic of each type of printing medium with respect to temperature.
In the case where the process of S608 is completed, in S609, the CPU 501 sets a deformation amount threshold. The deformation amount threshold in the present embodiment is a threshold for calculating an optimal temperature at which the deformation amount of the printing medium 105 is suppressed, and the present embodiment is configured such that the user can specify a desired threshold as the deformation amount threshold. The configuration may be such that, in S609, the CPU 501 sets the deformation amount threshold already specified by the user before the process of the flowcharts of
For example, as illustrated in
Moreover, as illustrated in
In S610, the CPU 501 determines the optimal temperature for the deformation amount threshold set in S609 based on the deformation characteristic calculated in S608,
Next, in S611, the CPU 501 compares the optimal temperature determined in S610 with an ink melting temperature. The ink melting temperature is a minimum temperature at which the latex resin contained in the latex ink used in the present embodiment melts, and is assumed to be 60° C. in the present embodiment. In the case where the CPU 501 determines that the optimal temperature determined based on the deformation amount threshold is equal to or higher than the ink melting temperature, the CPU 501 proceeds to S612. In S612, the CPU 501 determines the optimal temperature determined in S610 as the fixation temperature, and stores the optimal temperature in the EEPROM 504. Then, the CPU 501 terminates the process of the flowcharts of
As described above, according to the present embodiment, the optimal fixation temperature can be determined. Specifically, in the present embodiment, the desired deformation amount threshold is determined by user specification. Then, the temperature at which the deformation characteristic does not reach the deformation amount indicated by the deformation amount threshold is derived as the fixation temperature. Accordingly, it is possible to determine the fixation temperature without depending on the glass transition point of the printing medium. Thus, the optimal fixation temperature can be determined also for a printing medium whose glass transition point is lower than the heating temperature range of the fixing unit.
Although the example in which the process of determining the fixation temperature of the printing medium to be used in the printing is performed in the printing apparatus configured to print the user image is described in the above embodiments, the present disclosure is not limited to this. The printing operation of the user image on the printing medium may be performed in an apparatus separate from the printing apparatus in which the process of determining the fixation temperature is performed. Specifically, the form may be such that the above process is performed in a fixation temperature determination apparatus configured to determine the fixation temperature, and the determined fixation temperature is transmitted to another printing apparatus or an external apparatus such as a server.
Embodiment(s) of the present disclosure can also be realized by a computer of a system or apparatus that reads out and executes computer executable instructions (e.g., one or more programs) recorded on a storage medium (which may also be referred to more fully as a ‘non-transitory computer-readable storage medium’) to perform the functions of one or more of the above-described embodiment(s) and/or that includes one or more circuits (e.g., application specific integrated circuit (ASIC)) for performing the functions of one or more of the above-described embodiment(s), and by a method performed by the computer of the system or apparatus by, for example, reading out and executing the computer executable instructions from the storage medium to perform the functions of one or more of the above-described embodiment(s) and/or controlling the one or more circuits to perform the functions of one or more of the above-described embodiment(s). The computer may comprise one or more processors (e.g., central processing unit (CPU), micro processing unit (MPU)) and may include a network of separate computers or separate processors to read out and execute the computer executable instructions. The computer executable instructions may be provided to the computer, for example, from a network or the storage medium. The storage medium may include, for example, one or more of a hard disk, a random-access memory (RAM), a read only memory (ROM), a storage of distributed computing systems, an optical disk (such as a compact disc (CD), digital versatile disc (DVD), or Blu-ray Disc (BD)™), a flash memory device, a memory card, and the like.
While the present disclosure has been described with reference to exemplary embodiments, it is to be understood that the disclosure is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.
This application claims the benefit of Japanese Patent Application No. 2022-203289, filed Dec. 20, 2022 which is hereby incorporated by reference wherein in its entirety.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2022-203289 | Dec 2022 | JP | national |
