JP2017065165A - Head and printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a head in which a temperature of a head unit end part can be accurately measured and the head unit can be prevented from being enlarged, and a printer.SOLUTION: The head comprises: a head row having a plurality of head units for discharging liquid arranged parallely in a first direction; a holding portion for holding the head row; and a temperature measuring portion, provided in the holding portion, which measures a temperature of each head unit. The head row has a first head row and a second head row arranged parallely in a second direction crossing the first direction. The head units are arranged zigzag so that end parts of the head units of the first head row in the first direction and end parts of the head units of the second head row in the first direction are arranged at the same position in the first direction. The temperature measuring portion is positioned adjacent to the end parts of the head units.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a head including a head unit that discharges liquid (for example, ink) and a printer including the head.

  Conventionally, a head having a plurality of line heads in which a plurality of head units are arranged in parallel in a first direction has been proposed. The plurality of line heads are juxtaposed in a second direction orthogonal to the first direction, and the head units are arranged in a staggered manner.

  The line head is provided with a thermistor for measuring the temperature of the head. The thermistor is provided between the two head units in the first direction or provided inside the head unit (see, for example, Patent Documents 1 and 2).

JP 2013-230656 A JP 2007-296639 A

  When it is provided between two head units, the temperature of the portion where the two head units overlap in the first direction (the end of the head unit) cannot be measured accurately, and the piezoelectric element of the nozzle located at the end of the head unit On the other hand, an accurate pulse could not be given. As a result, there arises a problem that the joint is visually recognized in the image recorded on the paper.

  Further, when the thermistor is provided inside the head unit, the head unit is enlarged and the pitch between nozzles in the paper transport direction is increased. Therefore, when the paper transport speed changes due to wear of the paper transport roller, etc., the liquid (ink) ejected from the nozzle adheres to the paper at a position greatly deviated from the target position and is recorded. The problem arises that white streaks appear in the image.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a head and a printer that can accurately measure the temperature of the end of the head unit and prevent an increase in the size of the head.

  A head according to the present invention is provided with a head row having a plurality of head units that discharge liquid arranged in parallel in a first direction, a holding portion that holds the head row, and the holding portion. A temperature measuring unit that measures temperature, and the head row includes a first head row and a second head row arranged in parallel in a second direction intersecting the first direction, and the head row in the first direction The head units are staggered so that the end of the head unit of the first head row and the end of the head unit of the second head row in the first direction are arranged at the same position in the first direction. It is arrange | positioned and the said temperature measurement part is located next to the edge part of the said head unit, It is characterized by the above-mentioned.

  In the head and printer according to the present invention, since the temperature measuring unit is close to the end of the head, the temperature at the end of the head can be measured with high accuracy, and the piezoelectric element of the nozzle can be accurately measured. A simple pulse voltage. Further, since the temperature measuring part is not provided inside the head, it is possible to prevent the head from being enlarged.

FIG. 2 is a plan view schematically showing the printer according to the first embodiment. It is the schematic sectional drawing which made the II-II line shown in FIG. 1 the cutting line. It is a bottom view of an inkjet head. FIG. 3 is an enlarged vertical sectional view schematically showing a configuration near a nozzle of a head unit. It is a flowchart which shows the 1st drive process of a head unit. 10 is a flowchart showing a second drive process of the head unit according to the second embodiment. 14 is a flowchart showing a third drive process of the head unit according to the third embodiment. FIG. 10 is a bottom view of an ink jet head according to a fifth embodiment. FIG. 10 is an enlarged bottom view of an ink jet head according to a sixth embodiment. It is a graph which shows the relationship between the nozzle number in the 1st head row-the 4th head row, and the amount of ink discharge. FIG. 10 is a bottom view of an ink jet head according to a seventh embodiment.

(Embodiment 1)
Hereinafter, the present invention will be described with reference to the drawings illustrating a printer according to a first embodiment. FIG. 1 is a plan view schematically showing a printer.

  In FIG. 1, the downstream side in the conveyance direction (second direction) of the recording paper 100 is defined as the front side of the printer 1, and the upstream side in the conveyance direction is defined as the rear side of the printer 1. Further, a paper width direction (first direction) that is parallel to the surface (the surface parallel to the paper surface of FIG. 1) on which the recording paper 100 is transported and orthogonal to the transport direction is defined as the left-right direction of the printer 1. . The left side of the figure is the left side of the printer 1, and the right side of the figure is the right side of the printer 1. Further, a direction orthogonal to the conveyance surface of the recording paper 100 (a direction orthogonal to the paper surface of FIG. 1) is defined as the vertical direction of the printer 1. In FIG. 1, the front side is the upper side and the back side is the lower side. Below, it demonstrates using front, back, left, right, up and down suitably.

  As shown in FIG. 1, the printer 1 includes a housing 2, a platen 3, four inkjet heads 4 (liquid ejection devices), two transport rollers 5 and 6, and a control device 7.

  The platen 3 is placed flat in the housing 2. A recording sheet 100 is placed on the upper surface of the platen 3. The four inkjet heads 4 are juxtaposed in the front-rear direction (conveying direction) above the platen 3. The two transport rollers 5 and 6 are respectively arranged on the rear side (upstream side in the transport direction) and the front side (downstream side) with respect to the platen 3. The two transport rollers 5 and 6 are respectively driven by a motor (not shown) to transport the recording paper 100 on the platen 3 forward.

  The control device 7 includes a non-volatile memory such as a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), an EEPROM (Electrically Erasable Programmable Read-Only Memory), and various control circuits. (Application Specific Integrated Circuit). The control device 7 is connected to an external device 9 such as a PC so as to be able to perform data communication, and controls each unit of the printer 1 based on print data transmitted from the external device 9.

  For example, the control device 7 controls a motor that drives the conveyance rollers 5 and 6 to convey the recording paper 100 in the conveyance direction by the conveyance rollers 5 and 6, and controls the inkjet head 4 toward the recording paper 100. Ink is ejected. As a result, an image is printed on the recording paper 100.

  A plurality of head holding portions 8 are attached to the housing 2. The plurality of head holding portions 8 are arranged in parallel in the front-rear direction above the platen 3 and at a position between the two transport rollers 5 and 6. The head holding unit 8 holds the inkjet head 4.

  The four inkjet heads 4 eject inks of four colors, cyan (C), magenta (M), yellow (Y), and black (K), respectively. Each inkjet head 4 is supplied with ink of a corresponding color from an ink tank (not shown).

  2 is a schematic cross-sectional view taken along the line II-II shown in FIG. 1, and FIG. 3 is a bottom view of the inkjet head 4. As shown in FIGS. 2 and 3, each inkjet head 4 includes a rectangular plate-like holder 10 that is long in the paper width direction, and a plurality of head units 11 (heads) attached to the holder 10.

  A plurality of nozzles 24 are formed on the lower surface of each head unit 11. The plurality of nozzles 24 of each head unit 11 are juxtaposed along the paper width direction (arrangement direction), which is the longitudinal direction of the inkjet head 4, and constitutes a first head row 81 and a second head row 82. ing. The first head row 81 and the second head row 82 are juxtaposed in the transport direction, and the first head row 81 is located behind the second head row 82.

  As shown in FIG. 3, the left end of the head unit 11 of the first head row 81 and the right end of the head unit 11 of the second head row 82 are in the same position in the left-right direction. In other words, the left end portion of the head unit 11 in the first head row 81 and the right end portion of the head unit 11 in the second head row 82 overlap in the front-rear direction (overlap).

  As shown in FIG. 3, in the first head row 81, the temperature sensor 20 (temperature measuring unit) is arranged next to each of both ends of the head unit 11. In the second head row 82, the temperature sensor 20 is arranged in front of each of both end portions of the head unit 11. That is, the temperature sensor 20 is located outside the first head row 81 and the second head row 82 in the transport direction (second direction). The temperature sensor 20 is attached to the holder 10. The distance d1 between the end of the head unit 11 in the transport direction and the temperature sensor 20 is smaller than half (d2 / 2) of the distance d2 between the adjacent head units 11 in the arrangement direction.

  In the first head row 81 and the second head row 82, a paper pressing roller 40 that presses the recording paper 100 is appropriately disposed between the head units 11 that are below the inkjet head 4 and adjacent in the arrangement direction. The paper pressing roller 40 prevents the recording paper 100 from floating when the recording paper 100 moves at a high speed.

  The holder 10 is provided with a slit 10a. The head unit 11 and the control device 7 are connected by the flexible substrate 51, and the flexible substrate 51 is inserted through the slit 10a. The temperature sensor 20 and the control device 7 are connected by a wiring 52, and the wiring 52 is also inserted through the slit 10a. That is, the slit 10a also functions as a hole for inserting the wiring 52, and it is not necessary to newly provide a hole for inserting the wiring 52.

  The plurality of head units 11 are arranged side by side along the arrangement direction. The plurality of head units 11 are alternately arranged on the front side and the rear side in the transport direction. The left and right (arrangement direction) positions are shifted between the plurality of head units 11 arranged on the front side and the plurality of head units 11 arranged on the rear side. In the present embodiment, the plurality of head units 11 are arranged in parallel along a direction (paper width direction) orthogonal to the transport direction, but along a direction intersecting the transport direction at an angle other than 90 degrees. In other words, a plurality of head units 11 may be arranged obliquely.

  As shown in FIGS. 1 and 2, the reservoir 12 is provided above the plurality of head units 11. In FIG. 3, the reservoir 12 is not shown.

  The reservoir 12 is connected to an ink tank (not shown) via a tube 16 and temporarily stores ink supplied from the ink tank. The lower part of the reservoir 12 is connected to a plurality of head units 11, and ink is supplied from the reservoir 12 to each head unit 11.

  FIG. 4 is an enlarged longitudinal sectional view schematically showing the configuration of the head unit 11 near the nozzles. The head unit 11 includes a plurality of piezoelectric elements 39 disposed corresponding to the plurality of pressure chambers 26, respectively. In the present embodiment, a plurality of thin films including a film to be the lower electrode 31, a film to be the piezoelectric film 32, and a film to be the upper electrode 33 are sequentially formed on the upper surface of the vibration film 30, thereby An element 39 is formed.

  The vibration film 30 constitutes the upper surface portion of the pressure chamber 26. The pressure chamber 26 is partitioned by a plurality of partition walls 25 arranged in parallel in the arrangement direction. The partition wall 25 extends in the transport direction. The upper end portion of the partition wall 25 is connected to the vibration film 30, and the lower end portion of the partition wall 25 is connected to the nozzle plate 21. The nozzle plate 21 is provided with a nozzle 24 penetrating vertically.

  In the arrangement direction, the piezoelectric element 39 and the nozzle 24 are located between the adjacent partition walls 25. In other words, the piezoelectric element 39 and the nozzle 24 are arranged in each pressure chamber 26 partitioned by the partition wall 25.

  A piezoelectric film 32 is provided above the vibration film 30. A lower electrode 31 is disposed between the center of the lower surface of the piezoelectric film 32 in the arrangement direction and the center of the upper surface of the vibration film 30 in the arrangement direction. The piezoelectric film 32 covers the upper surface of the lower electrode 31 and both ends in the arrangement direction.

  Between the piezoelectric elements 39 adjacent in the arrangement direction, on the upper side of the vibration film 30, a groove 34 having a rectangular shape in plan view extending in the front-rear direction is formed in the piezoelectric film 32. In other words, the groove 34 is formed in the upper end portion of the partition wall 25 and the connecting portion of the vibration film 30. An upper electrode 33 is formed above the vibration film 30, the piezoelectric film 32, and the groove 34.

  The upper electrode 33 is connected to a ground wiring of COF (not shown), and the potential of the upper electrode 33 is always maintained at the ground potential. A driver IC (not shown) is mounted on the COF. The COF is connected to the control device 7 (see FIG. 1) of the printer 1, and the driver IC is electrically connected to the control device 7 via wiring on the COF.

  The driver IC generates and outputs a drive signal for driving the piezoelectric element 39 based on the control signal sent from the control device 7. Ink is supplied from the reservoir 12 to the pressure chamber 26. The piezoelectric element 39 is driven by a drive signal, and ink is ejected from the pressure chamber 26 through the nozzle 24.

The nonvolatile memory of the control device 7 stores a table indicating the relationship between the temperature based on the detection value of the temperature sensor 20 and the pulse voltage (drive signal) applied to the piezoelectric element 39. In the table, for example, the pulse voltage V _n is associated with the temperature T _n (n is a natural number). Generally, when the temperature is high, the pulse voltage applied to the piezoelectric element 39 is low.

  FIG. 5 is a flowchart showing the first driving process of the head unit 11. The control device 7 executes a first drive process for each head unit 11.

  The control device 7 acquires measurement values from both temperature sensors arranged at the left and right ends of the head unit 11 (step S1). And the average value of the acquired measured value is calculated (step S2), and a table is referred (step S3). The table is set so that the higher the average value of the measured values, the lower the pulse voltage.

  The control device 7 determines a pulse voltage corresponding to the average value in the table as a pulse voltage to be applied to the voltage element 39 of the head unit 11 (step S4), and outputs a drive signal to the driver IC (step S5).

  In the printer 1 according to the first embodiment, since the temperature sensor 20 is close to the left and right end portions of the head unit 11, the left and right end portion temperatures of the head unit 11 can be accurately measured, and the nozzle 24 An accurate pulse voltage can be applied to the piezoelectric element 39. Further, since the temperature sensor 20 is not provided inside the head unit 11, an increase in the size of the head unit 11 can be prevented. Further, since the enlargement of the head unit 11 can be prevented, the paper pressing roller 40 for pressing the recording paper 100 can be disposed between the head units 11 and the recording paper generated when the recording paper 100 moves at high speed. 100 floating can be prevented.

  In addition, the temperature sensor 20 can be arranged outside the head unit 11 in the transport direction, so that the end temperature of the head unit 11 can be measured with high accuracy. Further, the amount of liquid ejected from the head unit 11 can be controlled based on the average temperature at both ends of the head unit 11.

(Embodiment 2)
Hereinafter, the present invention will be described with reference to the drawings showing a printer 1 according to a second embodiment. Of the configurations according to the second embodiment, configurations similar to those of the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted. FIG. 6 is a flowchart showing the second driving process of the head unit 11.

  The control device 7 executes the second drive process for each head unit 11. A signal indicating the amount of ink (ejection amount) ejected from each nozzle 24 of the head unit 11 is input from the external device 9 to the control device 7.

  The control device 7 acquires a signal indicating the discharge amount at both the left and right ends of the head unit 11 from the external device 9 (step S11), and compares the two acquired discharge amounts (step S12). Examples of the ejection amount include the volume, weight, or duty ratio of the ink. The left and right ends of the head unit 11 overlap with other head units 11 adjacent in the front-rear direction in the left-right direction. For example, when there are 100 nozzles 24 in the overlapped area of the head unit 11, when ink is ejected from the 40 nozzles 24, the duty ratio becomes 40%.

  The control device 7 selects the temperature sensor 20 located on the side with the larger discharge amount among the temperature sensors 20 located on the left and right ends (step S13), and acquires the temperature measured by the selected temperature sensor 20 (step S13). S14).

  The control device 7 refers to the table (step S15), determines the pulse voltage corresponding to the measured value as the pulse voltage to be applied to the voltage element 39 of the head unit 11 (step S16), and outputs the drive signal to the driver IC. (Step S17).

  In the printer according to the second embodiment, one of the temperatures measured by each temperature sensor 20 is selected according to the discharge amount from both ends of the head unit 11, and based on the selected temperature, The amount of liquid ejected from the head unit 11 is controlled. For example, excessive discharge of ink can be prevented by controlling the discharge amount of the entire head unit 11 in correspondence with the temperature on the side with the larger discharge amount.

(Embodiment 3)
Hereinafter, the present invention will be described with reference to the drawings showing a printer 1 according to a third embodiment. Of the configurations according to the third embodiment, configurations similar to those of the first or second embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  FIG. 7 is a flowchart showing the third driving process of the head unit 11. The control device 7 executes the third drive process for each head unit 11. A signal indicating the amount of ink (ejection amount) ejected from each nozzle 24 of the head unit 11 is input from the external device 9 to the control device 7.

  The control device 7 acquires a signal indicating the discharge amount from the left and right ends of the head unit 11 (for example, the two nozzles 24 located at the left and right ends of the head unit 11) from the external device 9 (step S21), and the head unit. The measured values are acquired from the two temperature sensors 20 located at the left and right ends of 11 (step S22).

  The control device 7 performs a weighting operation on each measurement value based on the ratio of the two discharge amounts (step S23). For example, when the temperature at the left end is 10 ° C., the temperature at the right end is 20 ° C., and the ratio of the discharge amount between the left end and the right end is 1: 4, 10 * 1/5 + 20 * 4/5 = 18 ° C. It becomes.

  The control device 7 refers to the table (step S24), determines the pulse voltage corresponding to the calculation result of the weighting calculation as the pulse voltage to be applied to the voltage element 39 of the head unit 11 (step S25), and sets the drive signal to the driver IC. (Step S26).

  In the printer 1 according to the third embodiment, a weighting operation is performed on each temperature measured by each temperature sensor 20 according to the amount of ink ejected from both ends of the head unit 11, and the calculation result Based on the above, the amount of ink ejected from the head unit 11 can be controlled.

  In the first to third driving processes described above, instead of the table, a function relating to temperature and pulse voltage is set in the nonvolatile memory of the control device 7, and an average value is applied to the function to determine the applied voltage. May be.

(Embodiment 4)
Of the configurations according to the fourth embodiment, the present invention will be described below with reference to the drawings showing the printer 1 according to the fourth embodiment. The detailed explanation is omitted. As shown in FIG. 3, the temperature sensor 20 disposed on the rear side of the right end portion of the head unit 11 of the first head row 81 is also referred to as a temperature sensor 20 </ b> A (first temperature measuring unit), and the head of the first head row 81 The temperature sensor 20 disposed on the rear side of the left end portion of the unit 11 is also referred to as a temperature sensor 20B (second temperature measuring unit).

  With respect to the head unit 11 of the second head row 82 located on the right front side of the head unit 11 of the first head row 81, the temperature sensor 20 located on the left front side is also referred to as a temperature sensor 20C (third temperature measuring unit). With respect to the head unit 11 of the second head row 82 located on the left front side of the head unit 11 of the first head row 81, the temperature sensor 20 located on the right front side is also referred to as a temperature sensor 20D (fourth temperature measuring unit).

  The temperatures at the left and right ends of the head unit 11 of the first head row 81 are calculated as follows. The temperature at the right end of the head unit 11 is the average (first average) of the temperatures measured by the temperature sensors 20A and 20C. The temperature at the left end of the head unit 11 is the average (second average) of the temperatures measured by the temperature sensors 20B and 20D.

  In the fourth embodiment, the first average and the second average are used as temperatures at the right end portion and the left end portion of the head unit 11, and the first to third drive processes are executed as in the first to third embodiments. .

(Embodiment 5)
Hereinafter, the present invention will be described with reference to the drawings showing a printer 1 according to a fifth embodiment. Of the configurations according to the fifth embodiment, configurations similar to those of the first to fourth embodiments are denoted by the same reference numerals, and detailed description thereof is omitted. FIG. 8 is a bottom view of the inkjet head 4. In the fifth embodiment, the head unit 11 constituting the first head row 81 is also referred to as 11A, and the head unit 11 constituting the second head row 82 is also referred to as 11B.

  In the first head row 81, a temperature sensor 20 (fifth temperature measuring unit) is provided on the rear side of the left end portion of each head unit 11A, but the temperature sensor is provided on the rear side of the left end portion of each head unit 11A. 20 is not provided.

  Similarly, in the second head row 82, a temperature sensor 20 (sixth temperature measuring unit) is provided on the front side of the left end portion of each head unit 11B, but on the rear side of the left end portion of each head unit 11B. The temperature sensor 20 is not provided.

  Even in this case, the distance d1 between the end of the head unit 11 and the temperature sensor 20 in the transport direction is smaller than half (d2 / 2) of the distance d2 between the adjacent head units 11 in the arrangement direction.

  The temperatures at the left and right ends of the head unit 11A are determined as follows. The temperature measurement value of the temperature sensor 20 disposed on the rear side of the head unit 11A is the temperature at the left end of the head unit 11A. The temperature measurement value of the temperature sensor 20 disposed on the front side of the head unit 11B located on the right front side of the head unit 11A is the temperature at the right end of the head unit 11A.

  On the other hand, the temperatures at the left and right ends of the head unit 11B are determined as follows. The temperature measurement value of the temperature sensor 20 disposed on the front side of the head unit 11B is the temperature at the left end of the head unit 11B. The temperature measurement value of the temperature sensor 20 disposed on the rear side of the head unit 11A located on the right rear side of the head unit 11B is the temperature at the right end of the head unit 11B.

  In the fifth embodiment, similarly to the first to third embodiments, the first to third driving processes can be executed. For example, when the first to third driving processes are performed on the head unit 11A, when the temperature measurement value of the temperature sensor 20 is acquired, the temperature measurement value of the temperature sensor 20 disposed on the rear side of the head unit 11A is acquired. And the temperature measurement value of the temperature sensor 20 arrange | positioned at the front side of the head unit 11B located in the right front side of the head unit 11A is acquired.

  When the first to third driving processes are performed on the head unit 11B, when the temperature measurement value of the temperature sensor 20 is acquired, the temperature measurement value of the temperature sensor 20 arranged on the front side of the head unit 11B is acquired, and the head The temperature measurement value of the temperature sensor 20 arranged on the rear side of the head unit 11A located on the right rear side of the unit 11B is acquired.

  The temperature sensor 20 may be provided on the rear side of the right end portion of the head unit 11A, and the temperature sensor 20 may be provided on the front side of the right end portion of the head unit 11B.

(Embodiment 6)
Hereinafter, the present invention will be described with reference to the drawings showing a printer 1 according to a sixth embodiment. Of the configurations according to the sixth embodiment, configurations similar to those of the first to fifth embodiments are denoted by the same reference numerals, and detailed description thereof is omitted. FIG. 9 is an enlarged bottom view of the inkjet head 4, and FIG. 10 is a graph showing the relationship between the nozzle number and the ink ejection amount in the first head row 81 to the fourth head row 84. On the upper side of FIG. 10, a graph showing the relationship between the ejection amount of ink ejected from the nozzles 24 of each of the first head row 81 and the second head row 82 and the nozzle number (in ascending order from left to right) is described. ing. On the lower side of FIG. 10, a graph showing the relationship between the ejection amount of ink ejected from the nozzles 24 of the third head row 83 and the fourth head row 84 and the nozzle number (in ascending order from left to right) is described. Has been.

  As shown in FIG. 9, the inkjet heads 4 are arranged in front and rear. The inkjet head 4 located on the rear side includes the first head row 81 and the second head row 82 as described above. The inkjet head 4 located on the front side also includes the first head row 81 and the second head row 82, but here, the inkjet head 4 located on the front side is referred to as a third head row 83 and a fourth head row 84.

  As shown in the center of FIG. 9, the left end of the head unit 11 of the first head row 81 (third head row 83) and the right end of the head unit 11 of the second head row 82 (fourth head row 84) Are in the same position in the left-right direction. In other words, the left end portion of the head unit 11 of the first head row 81 (third head row 83) and the right end portion of the head unit 11 of the second head row 82 (fourth head row 84) overlap in the front-rear direction. (Overlapping). In FIG. 9, the region at the same position (overlap region) is shown as the O region. The O region is divided into, for example, a right O1 region, a left O2 region, and a central O3 region. The O region may be divided not only into three regions but also into two regions or four regions or more.

  As shown in the upper graph of FIG. 10, in the first head row 81, with respect to the O region, ink is discharged from the O1 region, and the discharge amount of the ink increases toward the left side in the O1 region. Controlled to be less. On the other hand, in the second head row 82, with respect to the O region, ink is ejected from the O1 to O3 regions, and the ejection amount of the ink is controlled to gradually increase toward the left side in the O1 region. The Therefore, the temperature sensors 20 are provided before and after the O1 region.

  On the other hand, in the third head row 83 and the fourth head row 84, ink is ejected from a region different from the inkjet head 4 located on the rear side with respect to the O region. As shown in the lower graph of FIG. 10, in the third head row 83, with respect to the O region, ink is ejected from the O1 and O2 regions, and the amount of ink ejection increases toward the left side in the O2 region. The discharge amount is controlled to be small. On the other hand, in the fourth head row 84, with respect to the O region, ink is ejected from the O2 and O3 regions, and the ejection amount of the ink is controlled to gradually increase toward the left side in the O2 region. The

  The reason why the transition area for changing the ink discharge amount is provided and the transition area is different between the head rows is as follows. Due to manufacturing error or aging deterioration, the ink discharge amount or discharge speed varies among the heads, and white stripes or black stripes occur on the recording paper 100. By providing the transition area, the nozzles to be used gradually move between the heads, so that the white streak is not noticeable. However, even if a transition region is provided, white stripes or black stripes may occur.

If the front inkjet head 4 (head rows 81, 82) and the rear inkjet head 4 (head rows 83, 84) of the same color are different from the front inkjet head 4, the transition area is the same. Slight white or black streaks are concentrated and white or black streaks are conspicuous. In the present embodiment, the front inkjet head 4 and the rear inkjet head 4 have different transition areas, so that the front inkjet head 4 and the rear inkjet head 4 have the same transition area. Thus, the white stripes or black stripes are dispersed and become less noticeable. In the present embodiment, since the temperature sensor 20 is arranged in each transition region that is different for each head row, white stripes or black stripes can be made more inconspicuous.
Therefore, in the third head row 83 and the fourth head row, the temperature sensors 20 are respectively provided before and after the O3 region different from the O1 region.

  In the O region, ink is ejected from different regions for each inkjet head 4. In other words, since each inkjet head 4 ejects a different color, ink is ejected from the region corresponding to the color in the O region.

  In the sixth embodiment, in the O region, the temperature sensor 20 is arranged at a position close to the transition region (region corresponding to each color of ink), so that the temperature of the end portion of the head unit 11 is measured with higher accuracy. can do.

  Also in the sixth embodiment, the distance d1 between the end of the head unit 11 and the temperature sensor 20 in the transport direction is smaller than half (d2 / 2) of the distance d2 between the adjacent head units 11 in the arrangement direction. (See FIG. 3). Further, the printer 1 according to the sixth embodiment can execute the first to third driving processes.

(Embodiment 7)
Hereinafter, the present invention will be described with reference to the drawings illustrating a printer according to a seventh embodiment. Of the configurations according to the seventh embodiment, configurations similar to those of the first to sixth embodiments are denoted by the same reference numerals, and detailed description thereof is omitted. FIG. 11 is a bottom view of the inkjet head 4.

  Temperature sensors 20 are provided on the right side of the right end of the head unit 11 and on the left side of the left end of the head unit 11, respectively. In this case, the distance d3 between the right end portion or the left end portion of the head unit 11 in the transport direction and the temperature sensor 20 is smaller than half (d2 / 2) of the distance d2 between the adjacent head units 11 in the arrangement direction. .

  Since the temperature sensor 20 is close to the left and right ends of the head unit 11, the temperature of the left and right ends of the head unit 11 can be accurately measured, and an accurate pulse voltage is applied to the piezoelectric element 39 of the nozzle 24. Can be given.

  In the seventh embodiment, the paper pressing roller 40 is not provided. However, when the distance between two temperature sensors 20 adjacent in the arrangement direction is sufficiently large, the paper pressing roller is provided between the two temperature sensors 20. 40 may be provided.

  It should be thought that embodiment disclosed this time is an illustration and restrictive at no points. The technical features described in each embodiment can be combined with each other, and the scope of the present invention is intended to include all modifications within the scope of claims and the scope equivalent to the scope of claims. Is done.

1 Printer 4 Inkjet head (head)
7 Control device 10 Holder (holding part)
11 Head unit 20 Temperature sensor (temperature measuring unit)
81-84 1st head row-4th head row (head row)

Claims (18)

A head row having a plurality of head units for discharging liquid arranged in parallel in the first direction;
A holding unit for holding the head row;
A temperature measuring unit that is provided in the holding unit and measures the temperature of each head unit;
The head row includes a first head row and a second head row arranged in parallel in a second direction intersecting the first direction,
An end of the head unit of the first head row in the first direction and an end of the head unit of the second head row in the first direction are arranged at the same position in the first direction. , The head units are arranged in a staggered manner,
The head is characterized in that the temperature measuring unit is located next to an end of the head unit. The head according to claim 1, wherein two temperature measuring units are arranged between two head units adjacent in the first direction. The head according to claim 1, wherein the temperature measuring unit is located next to an end of the head unit in the second direction. The head according to claim 3, wherein the temperature measuring unit is located outside the first head row and the second head row in the second direction. The head row further includes a third head row and a fourth head row arranged in parallel in a second direction intersecting the first direction,
The end of the head unit of the third head row in the first direction and the end of the head unit of the fourth head row in the first direction are arranged at the same position in the first direction. , The head units are arranged in a staggered manner,
Liquids having different colors are supplied to the first head row and the second head row, and the third head row and the fourth head row, respectively.
An area corresponding to each color is set at the end of the head unit,
The head according to claim 3 or 4, wherein the temperature measuring unit is arranged at a position corresponding to each region. The position of the region in the first direction corresponding to the color supplied to the first head row and the second head row, and the first corresponding to the color supplied to the third head row and the fourth head row. The head according to claim 5, wherein a position of the region in the direction is different. The temperature measuring unit is located next to both ends of the head unit in the first direction,
For each of the head units, a control unit that calculates an average of the temperatures measured by the two temperature measuring units and controls the amount of liquid ejected from the head unit based on the calculation result is provided. The head according to any one of claims 1 to 6. The head according to claim 7, wherein the control unit is configured to eject an amount of liquid corresponding to the calculated average temperature from the head unit. The temperature measuring unit is located next to both ends of the head unit in the first direction,
Depending on the amount of liquid discharged from both ends, one of the temperatures measured by each temperature measuring unit is selected, and the amount of liquid discharged from the head unit is controlled based on the selected temperature. The head according to claim 1, further comprising a control unit. The control unit is configured to compare the amount of liquid ejected from each of the both ends, and to select the temperature of the temperature measuring unit located next to the end of the head unit with a large amount of liquid. The head according to claim 9. The temperature measuring unit is located next to both ends of the head unit in the first direction,
For each temperature measured by each temperature measuring unit, a weighting operation is performed according to the amount of liquid ejected from both ends, and the liquid ejected from the head unit is calculated based on the calculation result of the weighting operation. The head according to any one of claims 1 to 6, further comprising a control unit that controls the amount. In the weighting calculation, the controller controls the ratio of the amount of liquid ejected from each of the one end and the other end of the head unit and each measurement positioned next to the one end and the other end of the head unit. The head according to claim 11, wherein a product of the temperature measured at the warm part is calculated. First and second temperature measuring units provided next to both end portions of the first head unit in the first head row;
It is provided next to each end of the two second head units in the second head row, and is arranged at a position corresponding to each of the first and second temperature measuring units in the first direction. Third and fourth temperature measuring sections,
The first average of the first and third temperature measuring units is calculated, the second average of the second and fourth temperature measuring units is calculated, and the head is calculated based on the first average or the second average. A head according to any one of claims 3 to 6, further comprising: a control unit that controls the amount of liquid ejected from the unit. The control unit selects the first average or second average according to the amount of liquid ejected from both ends of the first head unit, and based on the selected first average or second average, The head according to claim 13, wherein the amount of liquid ejected from the first head unit is controlled. The control unit performs a weighting operation according to the amount of liquid ejected from both ends of the first head unit with respect to the first average or the second average, and based on a calculation result of the weighting operation, The head according to claim 13, wherein the amount of liquid ejected from the first head unit is controlled. The controller calculates a third average that is an average of the first average or the second average, and controls the amount of liquid ejected from the first head unit based on the third average. 14. The head according to claim 13, A fifth temperature measuring unit is provided next to one end of the first head unit in the first head row,
A sixth temperature measuring unit is provided next to one end of the second head unit in the second head row,
The sixth temperature measuring unit is arranged at a position corresponding to the other end of the first head unit in the first direction,
The temperature measuring unit is not provided next to the other end of the first head unit and the second head unit,
The control unit calculates a fourth average that is an average of the fifth and sixth temperature measuring units, and controls the amount of liquid ejected from the head unit based on the fourth average. The head according to any one of claims 3 to 6. A transport section for transporting paper;
A printer comprising: the head according to claim 1, wherein recording is performed on paper conveyed to the conveyance unit.

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