JP2010167620A - Recording apparatus and control method of the recording apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a recording apparatus equipped with a drying device for drying a recording material after recording, wherein the recording material after recording is moderately dried by preventing insufficient drying and excessive drying. <P>SOLUTION: The temperature of a part in a first temperature measurement region is measured by a first temperature sensor 13 as a first measured temperature. When recording paper P is conveyed to a position where the part where the first measured temperature has been measured comes within a second temperature measurement region, the temperature of the part is measured by a second temperature sensor 14 as a second measured temperature (step S1). When it is determined that the first measured temperature and the second measured temperature are different from each other (Yes in step S2), and when the temperature difference is generated in consequence of a fall in the first measured temperature (Yes in step S3), the wind velocity of the warm wind from a warm wind unit 11 is raised (step S4). When the temperature difference is generated in consequence of a rise in the second measured temperature (No in step S3), the wind velocity of the warm wind from the warm wind unit 11 is lowered (step S5). <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a transport device that transports a recording material in a predetermined transport direction, a recording head that ejects ink onto the recording material transported by the transport device, and a downstream side in the transport direction from the ink ejection area of the recording head. The present invention relates to a recording apparatus including a drying device for drying ink ejected from a recording head onto a recording material, and a control method for the recording device.

In a recording apparatus such as an ink jet printer, a transport apparatus that transports a recording material in a predetermined transport direction, a recording head that ejects ink onto the recording material transported by the transport apparatus, and a transport direction from an ink ejection area of the recording head And a drying device for drying the ink ejected from the recording head onto the recording material on the downstream side of the recording device (see, for example, Patent Document 1 or 2). By providing such a drying device, it is possible to discharge the recording material after recording outside the device in a state where the ink ejected onto the recording material is sufficiently dried. Particularly in a recording apparatus that performs high-quality recording at high speed, such as a line head type ink jet printer, since a large amount of ink is ejected onto a recording material in a short time, recording is performed. The merit of providing is great.
JP 2002-292841 A JP 2001-341284 A

  However, for example, if the recording material after recording is discharged with insufficient drying by the drying device, the recording material is discharged in a state where the ejected ink is not sufficiently dried. In this case, when the user's hand touches the recording surface of the recording material after execution of the discharged recording, the recorded image or the like of the recording material is disturbed, or one of the inks jetted onto the recording material. There is a risk that the part may adhere to the user's hand. On the other hand, for example, if the recording material after execution of recording is excessively dried by the drying device, the moisture content of the recording material is greatly reduced by heat, and the recording material contracts beyond an allowable range, There is a risk of deformation such as warping and curling. Also, in a recording apparatus having a double-sided recording function, the recording material shrinks due to heat during front surface recording, which may reduce the recording dot formation position accuracy during back surface recording and reduce the recording accuracy. . Furthermore, excessive drying of the recording material by the drying device leads to wasteful energy consumption by the drying device, which is not preferable from the viewpoint of energy saving.

  In order to prevent the above-described insufficient drying and excessive drying and to achieve appropriate drying of the recording material after execution of recording, it is necessary to appropriately set the control parameters of the drying apparatus. Here, the control parameters of the drying device include, for example, the temperature of warm air, the amount of warm air in a drying device that sends warm air to the recording material and dries the recording material. Appropriate control parameters for the drying device include the characteristics of the ink used (water content, etc.), the characteristics of the recording material used (ink absorptivity, water content, etc.), the temperature of the environment in which the recording device is used, It depends on humidity etc.

  In this regard, Patent Document 1 describes that it is preferable to adjust the temperature and air volume of the warm air sent out by the drying device in consideration of these various conditions. However, in Patent Document 1, the interval between the recording material after execution of recording and the drying device is set to a predetermined interval or more, thereby preventing image quality deterioration due to ink flow on the recording material due to hot air. As long as it is disclosed. That is, Patent Document 1 discloses how to dry the recording material after execution of recording by preventing insufficient drying and excessive drying. There is no disclosure or suggestion about how to adjust the control parameters of the device.

  Patent Document 2 describes that the drying temperature and the air volume of the drying apparatus should be appropriately adjusted according to the conveyance speed of the recording material by the conveyance apparatus. However, Patent Document 2 describes that the setting of the drying temperature and the air volume of the drying apparatus is based on experience values and experimental values by experts, and specifically how and how the drying apparatus is dried. There is no disclosure or suggestion regarding the setting of temperature and air volume.

  The present invention has been made in view of such a situation, and its problem is to prevent insufficient drying and excessive drying in a recording apparatus including a drying apparatus for drying a recording material after recording is performed. Thus, it is intended to realize appropriate drying of the recording material after execution of recording.

  In order to achieve the above object, a first aspect of the present invention includes a transport device that transports a recording material in a predetermined transport direction, a recording head that ejects ink onto the recording material transported by the transport device, and A drying device for drying the ink ejected from the recording head onto the recording material downstream from the region in which the ink can be ejected by the recording head, and the ink can be dried by the drying device. Recording is performed in a first temperature measurement region set at a predetermined position in the region and a second temperature measurement region set downstream in the transport direction from the first temperature measurement region in the region that can be dried by the drying device. A temperature measuring device capable of measuring the temperature of the material; and a control device, wherein the control device measures a temperature of a portion of the recording material in the first temperature measurement region to obtain a first measured temperature. And the first measurement Means for measuring the temperature of the portion to be a second measured temperature when the recording material is conveyed to a position where the portion where the temperature is measured is within the second temperature measurement region; and the first measured temperature; And a means for adjusting the drying ability exhibited by the drying device so that the temperature difference relative to the second measurement temperature is sufficiently small.

  In general, the material drying process can be divided into three periods: a material preheating period, a constant rate drying period, and a reduced rate drying period. The material preheating period is the first stage of drying, and refers to the period from when the temperature of the material reaches the equilibrium temperature from the initial temperature. The constant rate drying period is the next stage of the material preheating period, and refers to a period during which all the heat flowing into the material is consumed for moisture evaporation while the material temperature is constant. The reduced rate drying period is the last stage in drying, and refers to a period during which part of heat is consumed for moisture evaporation and the rest is consumed for temperature rise of the material.

  The temperature of the recording material on which recording has been performed by ejecting ink from the recording head gradually rises as it begins to be heated by the drying device. However, until the temperature of the recording material reaches a certain temperature (equilibrium temperature), most of the heat energy is consumed for the temperature rise of the ink, so that the ink moisture hardly vaporizes due to the heat energy. That is, although the temperature of the recording material rises, the moisture content of the ink jetted onto the recording material is almost unchanged (material preheating period).

  Subsequently, when the temperature of the recording material reaches a certain temperature, the moisture of the ink ejected onto the recording material starts to vaporize little by little, and the ink is gradually dried. At this time, most of the heat energy is consumed when the moisture of the ink ejected onto the recording material is vaporized, so that the temperature of the recording material is maintained at a substantially constant temperature. In other words, the temperature of the recording material hardly changes at a substantially constant temperature, but the moisture content of the ink jetted onto the recording material gradually decreases and the ink gradually dries (the constant rate drying period). ).

  When the ink ejected onto the recording material is in a substantially dry state, the thermal energy that has been consumed for drying the ink until then is consumed for the temperature rise of the recording material (decreasing drying period). . If the recording material is further dried in this state, the temperature of the recording material gradually increases and the moisture content of the recording material decreases, thereby causing the recording material to shrink and warping the recording material. There is a risk of deformation such as curling.

  Recording is performed on the recording material conveyed by the conveying device by ejecting ink from the recording head. The recording material after recording is dried in the process of passing through the drying device and discharged outside the recording device. Here, for example, if the recording material drying process is still in the material preheating period when the recording material after recording has passed through the drying device, the ink jetted onto the recording material is almost dry. Therefore, the drying in the drying apparatus is insufficient. For example, when the drying temperature of the recording material in the drying device is low, or when the air volume of the drying device is small. On the contrary, when the recording material drying process has already reached the rate of drying when the recording material after recording has passed through the drying device, the recording material after recording has been excessively dried. There is a possibility that the recording material may be warped or curled. For example, when the drying temperature of the recording material in the drying device is high, or when the air volume of the drying device is large.

  That is, from the viewpoint of preventing the recording material after recording from being discharged in an insufficiently dried state, at least the recording material is dried before the recording material after recording passes through the drying device. The process needs to shift from the material preheating period to the constant rate drying period. Furthermore, from the viewpoint of preventing the recording material from being excessively dried, the portion where the recording material drying process proceeds to the reduced rate drying period before the recording material after recording passes through the drying device is minimized. It is desirable to reduce it.

  Therefore, in the present invention, in order to achieve appropriate drying of the recording material after execution of the recording as described above, first, the temperature of the portion in the first temperature measurement region of the recording material that is being dried by the drying device is set. The first measurement temperature is measured, and then the temperature of the recording material is measured when the recording material is transported to a position where the portion where the first measurement temperature is measured is within the second temperature measurement region. 2 Measurement temperature.

  Here, both the first temperature measurement region and the second temperature measurement region are set at predetermined positions in the region that can be dried by the drying device. Further, the second temperature measurement region is on the downstream side in the transport direction from the first temperature measurement region. And what is measured as the second measurement temperature is the temperature of the same part as the part where the first measurement temperature of the recording material is measured. Therefore, the second measured temperature is the temperature at the time when the drying time longer than that at the time of measuring the first measured temperature is equal to the distance in the transport direction between the first temperature measured region and the second temperature measured region.

  For this reason, for example, the fact that the second measurement temperature is lower than the first measurement temperature is not normally possible because the temperature of the recording material is lowered during drying by the drying device. it is conceivable that. On the other hand, for example, when the second measurement temperature is higher than the first measurement temperature, the temperature of the recording material rises between the first temperature measurement region and the second temperature measurement region. Therefore, the drying process of the recording material in this case is in a state where the drying before reaching the constant rate drying period is insufficient (material preheating period), or has already been transferred from the constant rate drying period to the decreasing rate drying period. Is considered excessive. For example, when the temperature difference between the first measurement temperature and the second measurement temperature is sufficiently small, the temperature of the recording material is substantially constant and almost changes between the first temperature measurement region and the second temperature measurement region. It will not be. Therefore, it is considered that the recording material drying process in this case has reached a constant rate drying period.

  That is, the recording material after recording is dried by adjusting the drying ability exhibited by the drying device so that the relative temperature difference between the first measurement temperature and the second measurement temperature is sufficiently small. It is possible to make the process reach the constant rate drying period. As a result, it is possible to reduce the possibility that the recording material will be discharged while the drying after the recording is insufficient. In addition, since the possibility that the drying process shifts to the decreasing rate drying period can be reduced as much as possible, there is a possibility that the recording material may be excessively dried and the recording material may be warped or curled. Can be reduced.

  Thus, according to the first aspect of the present invention, in the recording apparatus including the drying device for drying the recording material after the recording is performed, after the recording is performed by preventing insufficient drying or excessive drying. The effect of achieving appropriate drying of the recording material is obtained.

  According to a second aspect of the present invention, in the recording apparatus according to the first aspect described above, the control device has a sufficiently small relative temperature difference between the first measured temperature and the second measured temperature. When the relative temperature difference between the first measurement temperature and the second measurement temperature is caused by the decrease in the first measurement temperature, the drying is performed so as to improve the drying ability exhibited by the drying device. Means for changing a control parameter of the apparatus, and the first measurement temperature is increased by increasing the second measurement temperature from a state in which a relative temperature difference between the first measurement temperature and the second measurement temperature is sufficiently small. Means for changing a control parameter of the drying device so as to reduce a drying ability exhibited by the drying device when a relative temperature difference from the second measurement temperature occurs. Recording device That.

  When the relative temperature difference between the first measurement temperature and the second measurement temperature is sufficiently small to cause a relative temperature difference between the first measurement temperature and the second measurement temperature, the recording material is dried. Is considered to be in a state where it cannot reach the constant rate drying period from the material preheating period. In other words, it is considered that the drying ability exhibited by the drying device is insufficient due to, for example, a decrease in environmental temperature, an increase in environmental humidity, or an increase in ink jet density with respect to the recording material. At this time, the control parameters of the drying device are changed so as to improve the drying ability exhibited by the drying device. As a result, the drying device is maintained so that the relative temperature difference between the first measurement temperature and the second measurement temperature is sufficiently small, that is, the state where the recording material is appropriately dried by the drying device. The drying ability to be exhibited can be adjusted.

  The ink ejection density means an ink ejection amount per unit area of the recording surface of the recording material.

  On the other hand, if the relative temperature difference between the first measurement temperature and the second measurement temperature increases from a state in which the relative temperature difference is sufficiently small and a relative temperature difference occurs between the two, the recording material It is considered that some drying steps have already reached a decreasing rate drying period after a constant rate drying period. That is, it is considered that the drying ability exhibited by the drying device is in an excessive state due to, for example, an increase in environmental temperature, a decrease in environmental humidity, or a decrease in ink jet density with respect to the recording material. At this time, the control parameters of the drying device are changed so as to reduce the drying capacity exhibited by the drying device. As a result, the drying device is maintained so that the relative temperature difference between the first measurement temperature and the second measurement temperature is sufficiently small, that is, the state where the recording material is appropriately dried by the drying device. The drying ability to be exhibited can be adjusted.

  According to a third aspect of the present invention, in the recording apparatus according to the first aspect or the second aspect, the temperature measuring device is capable of measuring the temperature of the recording material in the first temperature measurement region. A recording apparatus comprising: a first temperature sensor; and a second temperature sensor capable of measuring the temperature of the recording material in the second temperature measurement region.

  According to such a feature, when the recording material after recording is discharged while being dried by the drying device, it is possible to continuously measure the first measurement temperature and the second measurement temperature, respectively. That is, when the dry state of the recording material by the drying device changes, it is possible to always detect the change in the dry state in real time. Thereby, for example, in comparison with an aspect in which the first measurement temperature and the second measurement temperature are alternately measured by reciprocating one temperature sensor between the first temperature measurement region and the second temperature measurement region, Responsiveness of detecting a change in the dry state can be further improved. Therefore, the state in which the recording material is appropriately dried by the drying device can be maintained with higher accuracy.

  According to a fourth aspect of the present invention, in the recording apparatus according to the third aspect, the temperature measuring device is movable in a direction in which the first temperature sensor and the second temperature sensor intersect the transport direction. The control device is configured to move the first ink to a portion having the highest ink ejection density within a range in which the temperature of the recording material can be measured by the first temperature sensor at the timing of measuring the first measurement temperature. In the recording apparatus, the temperature sensor is moved to measure the temperature of the portion as the first measurement temperature.

  According to such a feature, the control parameters of the drying apparatus are set based on the dry state of the portion where the ink ejection density is highest as much as possible, that is, based on the dry state of the portion of the recording material that is most difficult to dry. Can be adjusted. As a result, the drying process of the entire recording material after execution of recording that has passed through the drying device can be brought to the constant rate drying period with higher probability. Accordingly, it is possible to further reduce the possibility that the recording material is discharged while drying after recording is insufficient.

According to a fifth aspect of the present invention, there is provided a conveying device that conveys a recording material in a predetermined conveying direction, a recording head that ejects ink onto the recording material conveyed by the conveying device, and an ink that is ejected by the recording head. A drying device for drying the ink ejected from the recording head onto the recording material, and a predetermined position within the region that can be dried by the drying device, on the downstream side in the transport direction from the region that can be The temperature of the recording material can be measured in a second temperature measurement region that is set downstream of the first temperature measurement region and the first temperature measurement region in the region that can be dried by the drying device in the transport direction. And a temperature measuring device for measuring the temperature of a portion of the recording material in the first temperature measurement region of the recording material being dried by the drying device to be a first measured temperature. Process and A step of measuring the temperature of the recording material when the recording material is transported to a position where the portion where the first measurement temperature is measured is within the second temperature measurement region, and setting the temperature to the second measurement temperature; Adjusting the drying ability exhibited by the drying device so that the relative temperature difference between the first measurement temperature and the second measurement temperature is sufficiently small. This is a control method.
According to the invention described in the fifth aspect of the present invention, in the recording apparatus controlled by this control method, it is possible to obtain the same operational effects as the invention described in the first aspect described above.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

<Schematic configuration of inkjet printer>
First, a schematic configuration of an inkjet printer 50 as a “recording apparatus” according to the present invention will be described with reference to FIGS.
FIG. 1 is a plan view of a main part of an ink jet printer 50, and FIG. 2 is a side view of the main part.

  The ink jet printer 50 is a so-called line head type ink jet printer. The ink jet printer 50 includes an automatic feeding device 70 that feeds a recording paper P as a “recording material” to the inside of the ink jet printer 50. The ink jet printer 50 includes a transport driving roller 51, a transport driven roller 52, and a discharge device 57 that constitute a “transport device” that transports the recording paper P in the transport direction Y. Furthermore, the ink jet printer 50 includes a preheat driving roller 53 and a preheat driven roller 54 that heat the recording paper P before execution of recording to a predetermined temperature. Further, the inkjet printer 50 includes a first recording head row 61 and a second recording head that perform recording by forming dots on the recording surface of the recording paper P that is conveyed in the conveying direction Y while being supported by the first platen 55. A column 62 is provided.

  The automatic feeding device 70 includes a feeding cassette 71, a feeding roller 72, a guide slope 73, and feeding intermediate roller pairs 74 and 75. The feeding cassette 71 is placed and accommodated in a state where a plurality of recording papers P are stacked. The feeding roller 72 is rotated by a rotational driving force of a motor (not shown). The guide slope 73 is a slope for guiding the leading edge of the recording paper P to the nip point of the feeding intermediate roller pair 74. The feeding intermediate roller pair 74 and 75 is a roller pair including a driving roller that is rotated by a rotational driving force of a motor (not shown) and a driven roller that is rotatably supported.

  The recording paper P stacked on the feeding cassette 71 is in contact with the outer peripheral surface of the feeding roller 72 by the uppermost recording paper P, and along the guide slope 73 by the rotation of the feeding roller 72. Then, it is sent to the nip point of the pair of intermediate rollers 74 for feeding. The recording paper P advances along the feeding path by the feeding intermediate roller pairs 74 and 75 and is fed to a position where the leading end reaches the nip point between the transport driving roller 51 and the transport driven roller 52.

  The transport driving roller 51 is rotated by a rotational driving force of a motor (not shown) being transmitted. The transport driven roller 52 is pivotally supported so as to be driven to rotate, and is in contact with the outer peripheral surface of the transport drive roller 51 by a biasing force of a biasing means such as a spring (not shown). The preheat drive roller 53 is rotated by a rotational driving force of a motor (not shown) being transmitted. The preheat driven roller 54 is pivotally supported so as to be driven to rotate, and is in contact with the outer peripheral surface of the preheat drive roller 53 by a biasing force of a biasing means such as a spring (not shown). The recording paper P fed by the automatic feeding device 70 is transported in the transport direction Y on the first platen 55 by the drive rotation of the transport drive roller 51. The recording paper P is heated to a predetermined temperature by the preheat drive roller 53 and the preheat driven roller 54 on the upstream side of the first platen 55.

  The first recording head row 61 is a head row composed of a plurality of recording heads 611 to 614 arranged on the upstream side in the transport direction Y. The recording heads 611 to 614 are arranged at a constant interval in the width direction X (direction intersecting the transport direction Y). The second recording head row 62 is a head row including a plurality of recording heads 621 to 623 arranged on the downstream side in the transport direction Y. The recording heads 621 to 623 are arranged at a constant interval in the width direction X. The recording head 621 is disposed at a corresponding position between the recording head 611 and the recording head 612. Similarly, the recording head 622 is disposed at a position corresponding to between the recording head 612 and the recording head 613, and the recording head 623 is disposed at a position corresponding to between the recording head 613 and the recording head 614. Yes. In the recording heads 611 to 614 and 621 to 623, a nozzle row including a large number of ink ejecting nozzles (not shown) for ejecting ink is arranged on the head surface facing the first platen 55 for each ink color. ing. Ink of each color (cyan, magenta, yellow, black, etc.) is supplied from an ink cartridge (not shown) to the recording heads 611 to 614 and 621 to 623 via ink tubes.

  The first platen 55 is disposed at a position facing the first recording head row 61 and the second head row 62, and supports the recording paper P transported in the transport direction Y from the back side. The distance between the head surfaces of the recording heads 611 to 614 and 621 to 623 and the recording surface of the recording paper P is defined by the first platen 55. The first platen 55 is provided with caps CP1 to CP7 corresponding to the recording heads 611 to 614 and 621 to 623, respectively. The caps CP1 to CP7 are arranged to be movable up and down by a driving mechanism (not shown), and are raised during standby to seal the head surfaces of the recording heads 611 to 614 and 621 to 623. Thereby, nozzle clogging or the like due to solidification of the ink of the ink ejection nozzle is prevented. The caps CP1 to CP7 also function as ink discarding holes when performing so-called borderless recording or during preliminary ejection before recording.

  The windbreak plate 56 is a plate-like member disposed so as to block a space between the hot air unit 11 and the second recording head row 62 to be described later, and the hot air sent from the hot air unit 11 is the recording head 611. This is a member for preventing the ink from flowing into the ink ejection regions 614 and 621 to 623.

  The discharge device 57 includes a driven roller 571, a drive roller 572, a tension roller 573, a transport belt 574, and a suction fan 575. The driven roller 571 is pivotally supported so as to be driven to rotate, and the drive roller 572 rotates by receiving a rotational driving force of a motor (not shown). The conveyor belt 574 is suspended between a driven roller 571, a driving roller 572, and a tension roller 573 as shown in the figure, and a predetermined tension is applied by the tension roller 573. The transport belt 574 has a large number of small through holes, and suction force is generated on the outer peripheral surface side by suction with the suction fan 575 from the inner peripheral surface side. As a result, the recording sheet P after recording is attracted to the outer peripheral surface of the conveyance belt 574, and is conveyed and discharged in the conveyance direction Y by the rotation of the conveyance belt 574.

  The ink jet printer 50 further includes a warm air unit 11, a second platen 12, a first temperature sensor 13, and a second temperature sensor 14.

The hot air unit 11 and the second platen 12 as “drying devices” are disposed on the downstream side in the transport direction Y from the area where the recording heads 611 to 614 and 621 to 623 can eject ink. The warm air unit 11 sends warm air to the recording surface of the recording paper P after ink ejection, and dries the ink ejected on the recording surface of the recording paper P. The second platen 12 has a heater, thermistor, heater control circuit, and the like (not shown), and the recording paper P after ink ejection is discharged from the back surface side at a predetermined temperature via the transport belt 574 of the discharge device 57. The ink jetted onto the recording surface of the recording paper P is dried by heating.
The ink jet printer 50 according to the present invention may be configured to include only one of the hot air unit 11 and the second platen 12 as a “drying device”.

  The first temperature sensor 13 constituting the “temperature measuring device” is disposed in an area where the recording paper P can be dried by the hot air unit 11 and the second platen 12. The first temperature sensor 13 is supported by the slide rail 15 so as to be movable in the width direction X. A region in which the first temperature sensor 13 can measure the temperature of the recording paper P (a movable region of the first temperature sensor 13) is defined as a first temperature measurement region.

  The second temperature sensor 14 constituting the “temperature measurement device” is disposed downstream in the transport direction Y from the first temperature measurement region in the region where the recording paper P can be dried by the hot air unit 11 and the second platen 12. Is done. The second temperature sensor 14 is supported by the slide rail 15 so as to be movable in the width direction X. A region where the second temperature sensor 14 can measure the temperature of the recording paper P (a movable region of the second temperature sensor 14) is defined as a second temperature measurement region. The distance in the transport direction Y from the first temperature measurement region to the second temperature measurement region is preferably set to a longer distance as much as possible. Further, the second temperature measurement region by the second temperature sensor 14 is recorded by the hot air unit 11 and the second platen 12 in order to accurately grasp the dry state of the recording paper P by the hot air unit 11 and the second platen 12. It is preferable to provide the paper P on the downstream side in the transport direction Y as much as possible in the dry region.

  The first temperature sensor 13 and the second temperature sensor 14 may be any sensors that can measure the temperature of the recording paper P, but it is more preferable to employ a known radiation thermometer. Since the radiation thermometer measures the temperature of the recording paper P by measuring the intensity of infrared light and visible light radiated from the recording paper P, there is an advantage that the measurement can be performed at high speed and measurement is possible without contact. .

  The ink jet printer 50 is provided with a mechanism (not shown) that moves the first temperature sensor 13 and the second temperature sensor 14 in the width direction X by the rotational driving force of the motor. Specifically, an endless belt that is rotatably supported between pulleys is disposed along the slide rail 15, and a first temperature sensor 13 and a second temperature sensor 14 are connected to the endless belt. Yes. The first temperature sensor 13 and the second temperature sensor 14 can be moved in both directions in the width direction X by rotating the endless belt in both directions with a motor. The moving positions of the first temperature sensor 13 and the second temperature sensor 14 can be detected by, for example, a known linear encoder (not shown).

  The recording control unit 100 as a “control device” having a known microcomputer control circuit performs feeding control of the recording paper P, transport control of the recording paper P, ink ejection control from the recording heads 611 to 614 and 621 to 623, and the like. The recording on the recording paper P is performed. The recording control unit 100 controls the heating temperature of the recording paper P before recording by the preheat driving roller 53 and the preheat driven roller 54. Further, the recording control unit 100 controls the drying temperature of the hot air unit 11 and the second platen 12 and the air volume (wind speed) of the hot air sent out by the hot air unit 11. Output signals from the first temperature sensor 13 and the second temperature sensor 14 are input to the recording control unit 100.

FIG. 3 is a cross-sectional side view of a main part illustrating the structure of the hot air unit 11.
The hot air unit 11 includes a unit main body 111, a blower fan 112, and a heater 113. The unit main body 111 constitutes a hot air flow path having a substantially U-shaped side cross-sectional shape as shown in the figure. As the blower fan 112 rotates, air is sucked from the suction port 114, the sucked air is heated by the heater 113, and the heated air is sent as warm air from the warm air port 116 to the recording surface of the recording paper P. The Further, the warm air that has not been sent out from the warm air port 116 is discharged from the discharge port 115. The rotation control of the blower fan 112 and the temperature control of the heater 113 are executed by the recording control unit 100.

<Relationship between temperature of recording paper dried by drying device and ink moisture content>
When the ink of the recording paper P is dried by the warm air of the hot air unit 11 and the heating of the second platen 12, how the water content of the ink jetted onto the recording paper P and the temperature of the recording paper P change. It will be described with reference to FIG.

FIG. 4 is a graph schematically illustrating the relationship between the temperature of the recording paper P dried by the warm air of the warm air unit 11 and the heating of the second platen 12 and the ink moisture content.
The temperature of the recording paper P on which recording has been performed by ejecting ink from the recording heads 611 to 614 and 621 to 623 gradually increases due to the warm air of the warm air unit 11 and the heating of the second platen 12. However, until the temperature of the recording paper P reaches a certain temperature (equilibrium temperature), most of the heat energy is consumed for the temperature rise of the ink, so that the ink moisture hardly vaporizes due to the heat energy. That is, although the temperature of the recording paper P rises, the moisture content of the ink ejected onto the recording paper P is almost unchanged (material preheating period).

  Subsequently, when the temperature of the recording paper P reaches a certain temperature, the moisture of the ink jetted onto the recording paper P starts to vaporize little by little, and the ink gradually dries. At this time, most of the heat energy is consumed when the moisture of the ink ejected onto the recording paper P is vaporized, so that the temperature of the recording paper P is maintained at a substantially constant temperature. That is, the temperature of the recording paper P hardly changes at a substantially constant temperature, but the moisture content of the ink ejected onto the recording paper P gradually decreases and the ink gradually dries (the constant rate drying period). ).

  When the ink ejected onto the recording paper P is in a substantially dry state, the heat energy that has been consumed for drying the ink until then is consumed for the temperature rise of the recording paper P (decreasing drying period). . If the recording paper P is further dried in this state, the temperature of the recording paper P gradually rises and the moisture content of the recording paper P decreases, thereby causing the recording paper P to contract and warping the recording paper P. There is a risk of deformation such as curling.

  In other words, from the viewpoint of preventing the recording paper P after the recording from being discharged in an insufficiently dried state, the recording paper P after the recording is executed before passing the hot air unit 11 and the second platen 12. It is desirable that at least the drying process of the recording paper P shifts from the material preheating period to the constant rate drying period. Furthermore, from the viewpoint of preventing the recording paper P from being excessively dried, the drying process of the recording paper P is performed during the decreasing rate drying period until the recording paper P after the recording is performed passes through the hot air unit 11 and the second platen 12. It is desirable to minimize the number of parts that migrate.

<Control of Hot Air Unit 11 by Recording Control Unit 100>
Control of the hot air unit 11 by the recording control unit 100 will be described with reference to FIGS.

FIG. 5 is a grab schematically illustrating the relationship between the drying time by the hot air unit 11 and the second platen 12 and the temperature of the recording paper P.
In FIG. 5, a graph indicated by symbol A (a graph illustrated by a solid line) is a graph illustrating a state when the recording paper P is discharged in an appropriate dry state. The graph indicated by the symbol B (the graph shown by the alternate long and short dash line) shows the warm air unit 11 and the second airflow when the environmental temperature decreases, the environmental humidity increases, or when the recording is performed with a higher ink ejection density than usual. It is the graph which illustrated the state where the drying capacity which platen 12 exhibits is insufficient. A graph indicated by a reference symbol C (a graph illustrated by a broken line) indicates the warm air unit 11 and the second platen depending on, for example, a case where an increase in environmental temperature, a decrease in environmental humidity, or a recording with a lower ink ejection density than normal is performed. It is the graph which illustrated the state where the drying capacity which 12 exhibits is excessive.

  The region where the temperature of the recording paper P can be measured by the second temperature sensor 14 (second temperature measurement region) is larger than the region where the temperature of the recording paper P can be measured by the first temperature sensor 13 (first temperature measurement region). It is on the downstream side in the transport direction Y. The temperature measured by the second temperature sensor 14 as the second measured temperature is the same temperature as the part where the first measured temperature is measured by the first temperature sensor 13. Therefore, the second measured temperature is the temperature at the time when the drying time longer than that at the time of measuring the first measured temperature is equal to the interval in the transport direction Y between the first temperature sensor 13 and the second temperature sensor 14. .

  First, when the recording paper P is discharged in an appropriate dry state, the drying process of the recording paper P is in a state before reaching the constant rate drying period and before reaching the decreasing rate drying period. As described above, during the constant rate drying period, the temperature of the recording paper P is substantially unchanged at a substantially constant temperature with respect to the drying time. Therefore, for example, when the first measurement temperature measured by the first temperature sensor 13 and the second measurement temperature measured by the second temperature sensor 14 are both the temperature T1, and the temperature difference between the two is sufficiently small (FIG. 5). The temperature T1 is an equilibrium temperature, and most of the recording paper P is considered to be in a state where the temperature reaches the equilibrium temperature T1. That is, in this state, most of the recording paper P has a high possibility that the drying process has reached a constant rate drying period, and the recording paper P is highly likely to be discharged in an appropriate dry state.

  On the other hand, when the drying of the recording paper P is insufficient, it is considered that a part or the whole drying process of the recording paper P is a material preheating period before the constant rate drying period. As described above, during the material preheating period, the temperature of the recording paper P rises toward the equilibrium temperature T1 with respect to the drying time. Therefore, for example, when the second measured temperature measured by the second temperature sensor 14 is the equilibrium temperature T1, and the first measured temperature measured by the first temperature sensor 13 is a temperature T2 lower than the equilibrium temperature T1 (FIG. 5). The graph indicated by the reference symbol B), and at least a part of the drying process of the recording paper P is a material preheating period before the constant rate drying period, and therefore the recording paper P may be discharged in an insufficiently dried state. Is expensive.

  On the other hand, when the recording paper P is excessively dried, it is considered that the drying process of a part or the whole of the recording paper P exceeds the constant rate drying period and reaches the decreasing rate drying period. As described above, the temperature of the recording paper P rises above the equilibrium temperature T1 during the decreasing rate drying period. Therefore, for example, when the first measurement temperature measured by the first temperature sensor 13 is the equilibrium temperature T1, and the second measurement temperature measured by the second temperature sensor 14 is a temperature T3 higher than the equilibrium temperature T1 ( The graph indicated by the symbol C in FIG. 5), at least a part of the drying process of the recording paper P has reached the decreasing rate drying period, so that the recording paper P is likely to be discharged in an excessively dry state.

FIG. 6 is a grab schematically illustrating the relationship between the velocity of the warm air sent by the warm air unit 11 and the temperature of the recording paper P.
In the present invention, the recording paper P is moderately adjusted by increasing / decreasing the velocity (air volume) of the warm air as the “control parameter” of the warm air unit 11 according to the variation of the ambient temperature, the ambient humidity, the variation of the ink jet density, or the like. The state of being discharged in a dry state. On that basis, for example, the velocity of the warm air discharged from the warm air unit 11 is specified in advance in such a manner that the recording paper P is properly dried at a standard ambient temperature, humidity, etc. Then, it is preferable to increase / decrease the warm air speed of the warm air unit 11 using this as a reference value (initial value). Hereinafter, an example of a procedure for determining in advance the reference value of the wind speed of the hot air unit 11 will be described with reference to FIG.

  First, at a standard environmental temperature, environmental humidity, etc., the temperature of the hot air of the hot air unit 11 is fixed, and the temperature of the hot air of the hot air unit 11 is changed while the ink jet density is uniform. The pattern is recorded on the recording paper P. For example, a test pattern for forming ink dots at a constant ink ejection density while changing the warm air speed of the warm air unit 11 little by little from 1 to 10 m / s (for example, 5 m by 2 m / s) is recorded on the recording paper. Record in P. At this time, while the recording paper P on which the test pattern is recorded is dried by the hot air unit 11 and the second platen 12 and discharged, the change in the measurement temperature of the first temperature sensor 13 and the measurement temperature of the second temperature sensor 14 are detected. Get each change. The graph of FIG. 6 schematically illustrates the change in the measured temperature of the first temperature sensor 13 and the change in the measured temperature of the second temperature sensor 14. The range in which the measured temperature of the first temperature sensor 13 is constant at the equilibrium temperature (constant rate drying period) overlaps the range in which the measured temperature of the second temperature sensor 14 is constant at the equilibrium temperature (constant rate drying period). What is necessary is just to determine the reference value of the wind speed of the warm air unit 11 within the range of the wind speed (range of the wind speeds VL to VH).

  FIG. 7 is a flowchart illustrating a recording control procedure by the recording control unit 100. Hereinafter, description will be made with reference to the flowchart of FIG. 7 and also with reference to FIG. The procedure shown in the flowchart of FIG. 7 is a procedure that is repeatedly executed at a predetermined period from when the recording paper P is fed until it is discharged.

  First, with respect to the recording paper P that is being dried by the hot air unit 11 and the second platen 12, the temperature of the portion in the first temperature measurement region is measured by the first temperature sensor 13 as the first measurement temperature. When the recording paper P is conveyed to a position where the portion where the first measurement temperature is measured is within the second temperature measurement region, the temperature of the portion is measured by the second temperature sensor 14 to be the second measurement temperature ( Step S1) in FIG. More specifically, what is measured by the first temperature sensor 13 is the temperature at a measurement point arbitrarily selected within the first temperature measurement region (the movable region of the first temperature sensor 13). This measurement point can be selected by moving the first temperature sensor 13 in the width direction X, and it is preferable to select a portion having the highest ink ejection density in the first temperature measurement region. As a result, it is possible to further reduce the possibility that the recording paper P is discharged while drying after the recording is insufficient. The ink ejection density of the recording paper P after execution of recording can be specified from the contents of the recorded image data, for example. The temperature measured by the second temperature sensor 14 is the temperature of the same part as the part where the temperature is measured by the first temperature sensor 13.

  Subsequently, it is determined whether or not there is a temperature difference between the first measured temperature measured by the first temperature sensor 13 and the second measured temperature measured by the second temperature sensor 14 (step S2 in FIG. 7). In determining whether there is a temperature difference, the temperature difference is within a certain range (for example, a range of ± 1 ° C.) in consideration of variations in detection characteristics between the first temperature sensor 13 and the second temperature sensor 14. Whether or not the temperature difference is sufficiently small.

  When it is determined that the temperature difference between the first measured temperature measured by the first temperature sensor 13 and the second measured temperature measured by the second temperature sensor 14 is sufficiently small (No in step S2 in FIG. 7), recording is performed. There is a high possibility that the paper P is discharged in an appropriate dry state (state of graph A in FIG. 5). In this case, the procedure is terminated without changing the warm air speed of the warm air unit 11, and the current wind speed setting is maintained. On the other hand, it is determined that there is a temperature difference exceeding a certain range (for example, a range of ± 1 ° C.) between the first measurement temperature measured by the first temperature sensor 13 and the second measurement temperature measured by the second temperature sensor 14. In such a case (Yes in step S2 in FIG. 7), the temperature difference between the first measurement temperature and the second measurement temperature is in a range where the temperature difference is constant as the first measurement temperature decreases from a sufficiently small state. It is determined whether or not it has exceeded (step S3 in FIG. 7).

  When the temperature difference exceeds a certain range due to the decrease in the first measurement temperature (Yes in step S3 in FIG. 7), the drying capacity exhibited by the hot air unit 11 and the second platen 12 is insufficient. It is considered that this is a state (state of graph B in FIG. 5). Therefore, in this case, the warm air speed of the warm air unit 11 is increased (step S4 in FIG. 7). By increasing the speed of the warm air of the warm air unit 11, the drying ability exhibited by the warm air unit 11 is improved. Thereby, the hot air unit 11 exhibits so that the relative temperature difference between the first measurement temperature and the second measurement temperature is sufficiently small, that is, the state in which the recording paper P is appropriately dried is maintained. The drying ability to adjust can be adjusted.

  On the other hand, when the temperature difference does not exceed a certain range due to the decrease in the first measurement temperature, that is, when the temperature difference exceeds a certain range due to the increase in the second measurement temperature. (No in step S3 in FIG. 7), it is considered that the drying capacity exhibited by the hot air unit 11 and the second platen 12 is in an excessive state (state of graph C in FIG. 5). Therefore, in this case, the wind speed of the warm air of the warm air unit 11 is lowered (step S5 in FIG. 7). Decreasing the wind speed of the warm air unit 11 reduces the drying ability exhibited by the warm air unit 11. Thereby, the hot air unit 11 exhibits so that the relative temperature difference between the first measurement temperature and the second measurement temperature is sufficiently small, that is, the state in which the recording paper P is appropriately dried is maintained. The drying ability to adjust can be adjusted.

  It should be noted that, as a case where the temperature difference between the first measurement temperature and the second measurement temperature exceeds a certain range, it is usually not considered that the second measurement temperature is lower than the first measurement temperature. However, since there is a possibility of erroneous detection or the like, when such a state is detected, for example, the procedure returns to the procedure of step S1 in FIG. 7 to measure the first measurement temperature and the second measurement temperature again. Just do it. Or you may determine with the 1st temperature sensor 13 or the 2nd temperature sensor 14 having failed.

  As described above, the present invention maintains a state in which the relative temperature difference between the first measured temperature measured by the first temperature sensor 13 and the second measured temperature measured by the second temperature sensor 14 is sufficiently small. The warm air speed (air volume) of the warm air unit 11 is adjusted. As a result, even if environmental temperature, environmental humidity, or the like changes, the drying process of the recording paper P after execution of recording can be brought into a state where the constant rate drying period has been reached. That is, it is possible to reduce the possibility that the recording paper P is discharged while the drying after the recording is insufficient. In addition, since the possibility that the drying process shifts to the decreasing rate drying period can be reduced as much as possible, there is a possibility that the recording paper P is excessively dried after execution of the recording and the recording paper P is deformed such as warping or curling. Can be reduced.

  Therefore, according to the present invention, in the recording apparatus including the drying device for drying the recording paper P after the recording is performed, the drying of the recording paper P after the recording is performed is prevented by preventing insufficient drying and excessive drying. can do.

  In the present invention, the “temperature measuring device” includes a sensor for measuring the temperature of the recording paper P in the first temperature measurement area and a sensor for measuring the temperature of the recording paper P in the second temperature measurement area, as in the above embodiment. Are preferably provided separately. Thereby, the first measurement temperature and the second measurement temperature can be continuously measured individually and continuously. That is, when the dry state of the recording paper P by the hot air unit 11 and the second platen 12 changes, the change in the dry state can always be detected in real time. Therefore, the state in which the recording paper P is appropriately dried by the hot air unit 11 and the second platen 12 can be maintained with higher accuracy.

  Further, in the present invention, in order to further reduce the possibility that the recording paper P is discharged in an insufficiently dried state, the relative temperature difference between the first measurement temperature and the second measurement temperature is sufficiently small (constant rate drying). In the period), it is more preferable to maintain the state immediately before the second measured temperature starts to rise (shifts to the decreasing rate drying period). More specifically, for example, the control of the hot air unit 11 is performed so as to improve the drying ability exhibited by the hot air unit 11 from a state in which the relative temperature difference between the first measurement temperature and the second measurement temperature is sufficiently small. The parameters (warm air temperature, wind speed, etc.) may be changed stepwise, and when the second measured temperature starts to rise, adjustment may be made so that the control parameter is returned to the control parameter one step or several steps before that.

<Modification>
The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the invention described in the claims, and these are also included in the scope of the present invention. Needless to say. For example, the present invention can be implemented not only in the above-described line head type ink jet printer but also in a known serial head type ink jet printer, and the same effects can be obtained.

  In the present invention, the “drying device” may be any device as long as it can dry the ink ejected onto the recording paper P, and the hot air unit 11 and the second platen 12 of the above-described embodiment. It is not specifically limited to. For example, you may comprise using a well-known dehumidification dryer etc., and you may comprise combining a warm air unit and a dehumidification dryer.

  In the present invention, the “temperature measurement device” may be configured to alternately measure the temperature of the first temperature measurement region and the temperature of the second temperature measurement region with one temperature sensor. For example, this can be realized by providing a mechanism that supports the temperature sensor so as to be movable between the first temperature measurement region and the second temperature measurement region, and that can move the temperature sensor by the rotational driving force of the motor.

  In the present invention, the “temperature measuring device” is provided with two temperature sensors, ie, the first temperature sensor 13 and the second temperature sensor 14 as in the above embodiment, for example, the second temperature sensor 14 is moved in the transport direction. It is good also as a structure which can be supported by the support structure movable also to Y, and can adjust the relative space | interval of the conveyance direction Y of the 1st temperature sensor 13 and the 2nd temperature sensor 14. FIG.

  Further, in the above embodiment, the “control parameter” has been described by exemplifying the temperature (air volume) of the warm air of the warm air unit 11. However, for example, the temperature of the warm air unit 11 or the second platen 12 is exactly the same principle. The present invention can be applied. This is because by adjusting the temperature of the hot air unit 11 or the second platen 12, the drying ability exhibited by them can be adjusted. Therefore, for example, the present invention can be implemented by adjusting the temperature of the hot air unit 11 or the second platen 12 so that the relative temperature difference between the first measurement temperature and the second measurement temperature is kept sufficiently small. Is possible.

  More specifically, when it is determined that the temperature difference between the first measured temperature measured by the first temperature sensor 13 and the second measured temperature measured by the second temperature sensor 14 is sufficiently small (step of FIG. 7). No in S2), the procedure is terminated without changing the drying temperature of the hot air unit 11 and the second platen 12, and the current temperature setting is maintained. In addition, when the temperature difference exceeds a certain range due to the decrease in the first measurement temperature (Yes in step S3 in FIG. 7), the drying temperature of the hot air unit 11 or the second platen 12 is increased. On the other hand, when the temperature difference reaches a certain range due to the increase in the second measurement temperature (No in step S3 in FIG. 7), the drying temperature of the hot air unit 11 or the second platen 12 is lowered. Thereby, the warm air unit 11 and the first air temperature unit 11 and the second air temperature unit 11 are maintained so that the relative temperature difference between the first measurement temperature and the second measurement temperature is sufficiently small, that is, the state in which the recording paper P is appropriately dried. The drying capacity exhibited by the two platen 12 can be adjusted.

  Furthermore, in the inkjet printer 50 of the above-described embodiment, the present invention adjusts both the drying temperature of the hot air unit 11 and the second platen 12 and the air velocity (air volume) of the hot air of the hot air unit 11 to adjust the first temperature. A state where the relative temperature difference between the measurement temperature and the second measurement temperature is sufficiently small may be maintained. As a result, the range of increase / decrease adjustment of the drying ability exhibited by the hot air unit 11 and the second platen 12 can be made wider, so that the state in which the recording paper P is appropriately dried can be more reliably maintained. It becomes possible. In particular, the adjustment of the drying temperature of the hot air unit 11 and the second platen 12 is more effective for fluctuations in the environmental temperature, and the air velocity ( Adjustment of air volume is more effective.

The principal part top view of an inkjet printer. The principal part side view of an inkjet printer. The principal part side sectional view which illustrated the structure of the warm air unit. The graph which illustrated the relationship between the ink moisture content with respect to drying, and the temperature of a recording paper. A grab schematically illustrating the relationship between the drying time and the temperature of the recording paper. A grab schematically showing the relationship between the air speed of the hot air unit and the temperature of the recording paper. 6 is a flowchart illustrating a recording control procedure performed by a recording control unit.

DESCRIPTION OF SYMBOLS 11 Hot air unit, 12 2nd platen, 13 1st temperature sensor, 14 2nd temperature sensor, 50 inkjet printer, 51 conveyance drive roller, 52 conveyance driven roller, 53 preheat drive roller, 54 preheat driven roller, 55 1st platen 56 Windproof plate, 57 Ejector, 61 First recording head row, 62 Second recording head row, 70 Automatic feeding device, 100 Recording control unit, P recording paper, X width direction, Y transport direction,

Claims (5)

A transport device for transporting a recording material in a predetermined transport direction;
A recording head for ejecting ink onto a recording material conveyed by the conveying device;
A drying device for drying the ink ejected from the recording head to the recording material on the downstream side in the transport direction from the region where the ink can be ejected by the recording head;
A first temperature measurement region set at a predetermined position in an area that can be dried by the drying device and a first temperature measurement region that is set downstream of the first temperature measurement region in the region that can be dried by the drying device in the transport direction. A temperature measuring device capable of measuring the temperature of the recording material in two temperature measuring areas;
A control device,
The control device is configured to measure a temperature of a portion of the recording material in the first temperature measurement region to obtain a first measurement temperature;
Means for measuring the temperature of the portion to be measured when the recording material is conveyed to a position where the portion where the first measurement temperature is measured is within the second temperature measurement region;
Means for adjusting the drying ability exhibited by the drying device so as to maintain a sufficiently small relative temperature difference between the first measurement temperature and the second measurement temperature. Recording device. 2. The recording apparatus according to claim 1, wherein the control device is configured to reduce the first measurement temperature from a state in which a relative temperature difference between the first measurement temperature and the second measurement temperature is sufficiently small. Means for changing a control parameter of the drying device so as to improve a drying ability exhibited by the drying device when a relative temperature difference between the first measurement temperature and the second measurement temperature occurs;
When the second measurement temperature rises from a state where the relative temperature difference between the first measurement temperature and the second measurement temperature is sufficiently small, the relative relationship between the first measurement temperature and the second measurement temperature. And a means for changing a control parameter of the drying device so as to reduce a drying ability exhibited by the drying device when a temperature difference occurs.   3. The recording apparatus according to claim 1, wherein the temperature measuring device includes a first temperature sensor capable of measuring a temperature of the recording material in the first temperature measurement region, and a recording material in the second temperature measurement region. And a second temperature sensor capable of measuring the temperature of the recording apparatus. The recording apparatus according to claim 3, wherein the temperature measuring device is supported so that the first temperature sensor and the second temperature sensor can move in a direction intersecting the transport direction,
The control device moves the first temperature sensor to a portion having the highest ink ejection density within a range in which the temperature of the recording material can be measured by the first temperature sensor at the timing of measuring the first measurement temperature. The recording apparatus is characterized in that the temperature of the part is measured as the first measurement temperature. A transport device for transporting a recording material in a predetermined transport direction;
A recording head for ejecting ink onto a recording material conveyed by the conveying device;
A drying device for drying the ink ejected from the recording head to the recording material on the downstream side in the transport direction from the region where the ink can be ejected by the recording head;
A first temperature measurement region set at a predetermined position in an area that can be dried by the drying device and a first temperature measurement region that is set downstream of the first temperature measurement region in the region that can be dried by the drying device in the transport direction. In a method for controlling a recording apparatus, comprising: a temperature measuring device capable of measuring the temperature of a recording material in two temperature measurement regions;
Measuring a temperature of a portion in the first temperature measurement region of the recording material being dried by the drying device to be a first measurement temperature;
A step of measuring the temperature of the portion to be measured when the recording material is conveyed to a position where the portion where the first measurement temperature is measured is within the second temperature measurement region;
Adjusting the drying ability exhibited by the drying device so that the relative temperature difference between the first measurement temperature and the second measurement temperature is sufficiently small. Control method of recording apparatus.

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