JP2008074053A - Inkjet recording apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make a driver chip hardly overheated when a flushing signal is fed to an actuator for delivering ink from an ink delivering opening. <P>SOLUTION: The driver chip selectively feeds a delivering signal Sg1, the flushing signal Sg2 and a flushing signal Sg3 with a smaller frequency than that for the flushing signal Sg2 to the actuator for delivering the ink from the ink delivering opening. A temperature sensor is provided on the driver chip. The driver chip is controlled so that the flushing signal Sg2 is fed when the temperature of the driver chip indicated by the temperature sensor is lower than a specified threshold value, and the flushing signal Sg3 is fed when the temperature is not lower than the specified threshold value. When the temperature of the driver chip reaches the specified threshold value or higher, such the flushing signal that suppresses heat generation from the driver chip is selected thereby. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an ink jet recording apparatus having a driver chip that outputs a signal for ejecting ink.

  An ink jet recording apparatus provided with an ejection head having an ejection port for ejecting ink has a driver chip that supplies an ejection signal for ejecting ink to an actuator for ejecting ink from the ejection port, as disclosed in Patent Document 1. There is something. When the ejection signal is supplied from the driver chip, the actuator is driven and ink is ejected from the ejection port of the ejection head, thereby forming a desired image on the printing paper.

  By the way, when the period during which the ejection signal is not supplied to the actuator exceeds a certain length, there may be a problem in the subsequent ejection of ink. This is because the ink around the ink flow path and the discharge port stays for a long time and the viscosity of the ink increases. In order to avoid such a problem, even when ink is not ejected over a long period of time, it is conceivable to perform flushing periodically by supplying a signal to the actuator. Accordingly, the actuator is driven even during a period when ink is not ejected, and the ink remaining around the ejection port is moved, so that problems such as an increase in the viscosity of the ink are less likely to occur.

  If a discharge signal is supplied to the actuator when performing the flushing as described above, ink may be discharged from the discharge port, and the print paper or the inside of the apparatus may be contaminated with unnecessary ink. It will also be consumed. Therefore, as in Patent Document 2, it is preferable that the flushing as described above is performed by supplying a signal having a pulse train that does not eject ink to the actuator.

JP 2006-62211 A JP 2006-142676 A

  On the other hand, when the driver chip supplies a signal having a pulse train for flushing as described above to the actuator, the temperature of the driver chip rises due to heat generation. As a result, if the driver chip is overheated, the driver chip may malfunction or be damaged.

  An object of the present invention is to provide an ink jet recording apparatus in which a driver chip is less likely to overheat when supplying a flushing signal.

  The inkjet recording apparatus of the present invention supplies a discharge head, which has a discharge port for discharging ink and an actuator for discharging ink from the discharge port, and a discharge signal, which is a signal for discharging ink from the discharge port, to the actuator. A driver chip that supplies the actuator with a flushing signal comprising a pulse train that does not eject ink from the ejection port, a temperature measuring unit that measures the temperature of the driver chip, and a driver chip measured by the temperature measuring unit. Supplying condition changing means for changing the frequency of a pulse included in the flushing signal supplied by the driver chip to a smaller one when the temperature becomes a predetermined threshold value or more is provided.

  According to the present invention, ink is stably ejected by supplying a flushing signal, and the frequency of the flushing signal is reduced so that heat generation from the driver chip is suppressed when the temperature of the driver chip exceeds a threshold value. Control is made. This makes it difficult for the temperature of the driver chip to become excessive.

  Further, in the present invention, the supply condition changing means may change the pulse frequency so that a product of the pulse frequency and the length of the supply period of the flushing signal is not less than a predetermined value after the pulse frequency is changed. It is preferable to change the supply period together with the frequency. According to this configuration, the supply period of the flushing signal is changed together with the frequency of the pulse so that the number of pulses included in the flushing signal supplied to the actuator is equal to or greater than a predetermined value. Therefore, after the frequency change, the number of pulses that can stabilize the ejection of ink is ensured.

  In the present invention, the transport unit that transports the recording medium to a position facing the ejection port, and the ejection signal to the actuator so as to form an image on the recording medium transported by the transport unit. Main control unit that controls the transport unit and the print control unit so that the print control unit to be supplied to the chip and the supply period after the change by the supply condition change unit and the period during which an image is formed on the recording medium do not overlap. It is preferable to further comprise a control means. According to this configuration, since the flushing signal is supplied between the image formations, the supply of the flushing signal prevents the ink from being ejected during the image formation while the ink is stably ejected during the image formation. Control is done so that there is no.

  The present invention further includes waveform generation means for supplying a plurality of the flushing signals having different waveforms to the driver chip, and the supply condition changing means is configured so that the temperature of the driver chip is less than the threshold value. A signal instructing which of the plurality of flushing signals transmitted by the waveform generation means is supplied to the actuator is supplied to the driver chip, and the driver chip generates the signal generated by the waveform generation means. Preferably, the flushing signal indicated by the signal from the supply condition changing means is selected from a plurality of flushing signals, and the selected flushing signal is supplied to the actuator. According to this configuration, the frequency of the flushing signal can be adjusted with a simple configuration by selectively supplying any one of the plurality of flushing signals generated by the waveform generation means to the actuator.

  Also, in the present invention, two pieces of flushing information respectively indicating any two of the plurality of flushing signals generated by the waveform generation unit are stored in a temperature region below the predetermined threshold and a temperature region above the predetermined threshold. Storage means for storing the information in association with each of the plurality of flushing signals generated by the waveform generation means, wherein the supply condition changing means is a temperature of the driver chip measured by the temperature measurement means. It is preferable that a signal instructing to supply the flushing signal indicated by the flushing information stored in the storage unit in association with the temperature region included is supplied to the driver chip. According to this configuration, a signal indicating which flushing signal should be supplied can be supplied to the driver chip with a simple configuration in which which flushing signal is appropriate for the temperature of the driver chip is stored.

  The following is a description of an inkjet printer 1 (hereinafter simply referred to as “printer 1”) that is an example of a preferred embodiment of the present invention. FIG. 1 is a diagram illustrating a schematic configuration of the entire printer 1.

  The printer 1 has four inkjet heads 100. These inkjet heads 100 are arranged along the sub-scanning direction (printing paper conveyance direction). In the present embodiment, the inkjet head 100 is fixed to a housing (not shown) of the printer 1. That is, it is fixed with respect to the printing paper in the main scanning direction (the width direction of the printing paper or the direction orthogonal to the transport direction), and the interval between the inkjet heads 100 is also fixed in the sub-scanning direction. The four inkjet heads 100 eject different colors of ink. For example, yellow, magenta, cyan, and black inks are ejected, respectively. In FIG. 1, the main scanning direction indicates the direction from the back to the front, and the sub-scanning direction indicates the direction toward the right.

  The inkjet head 100 has a head main body 100a (discharge head). The head main body 100a is formed with a plurality of ink discharge ports and ink flow paths (all not shown) communicating with the respective ink discharge ports. The ink discharge port is formed in the lower surface of the head main body 100a, and the ink flow path is formed in the head main body 100a. At one end of the ink flow path, an inflow port through which ink from an ink supply source (not shown) such as an ink tank flows is formed. Thus, ink from the ink supply source is ejected from the ink ejection port via the ink flow path. In the present embodiment, it is assumed that a large number of ink discharge ports are arranged on the lower surface of the head main body 100a along the main scanning direction and the sub-scanning direction.

  The printer 1 has a paper stocker 180 as a container for storing printing paper. A large number of printing sheets are stacked and stored in the sheet stocker 180. Further, the printer 1 has a paper transport unit 130. The paper transport unit 130 includes a pickup roller 131, a nip roller 132, a driven roller 133, a belt roller 134, and a transport belt 135.

  The pickup roller 131 is installed above the paper stocker 180 and is a roller for feeding the uppermost printing paper of the paper stocker 180 out of the paper stocker 180. The driven roller 133 and the belt roller 134 are disposed at the same position in the vertical direction and spaced apart from each other in the sub-scanning direction. Both the driven roller 133 and the belt roller 134 have a rotation shaft arranged in parallel with the main scanning direction, and are installed in the printer 1 so as to rotate around the rotation shaft. The rotation shaft of the belt roller 134 is connected to the rotation shaft of a drive motor (not shown). As a result, the drive motor rotates the belt roller 134 in the direction of the arrow in FIG. A conveyor belt 135 is wound around the driven roller 133 and the belt roller 134. When the drive motor rotates the belt roller 134, the transport belt 135 travels around the driven roller 133 and the belt roller 134 at a constant speed in the clockwise direction in the drawing. A paper receiver 190 is provided on the right side of the belt roller 134.

  The nip roller 132 has a rotating shaft arranged in parallel with the main scanning direction, and is installed in the printer 1 so as to rotate around the rotating shaft. Further, the lower end of the nip roller 132 is urged toward the upper surface of the conveying belt 135 by the urging means (not shown). When the conveyance belt 135 rotates, the nip roller 132 receives frictional force from the conveyance belt 135 and rotates counterclockwise around the rotation axis.

  The printer 1 also has a print control unit 120. The print control unit 120 controls the overall operation of the printer 1 such as ink ejection by the inkjet head 100 and paper conveyance by the paper conveyance unit 130. Then, as will be described later, the print control unit 120 receives image data from a PC (Personal Computer) or the like, and forms an image on a print sheet based on the image data, and the inkjet head 100 and the sheet transport unit 130. To control. The following is an outline of steps in which an image is formed on the printing paper P by the inkjet head 100 and the paper transport unit 130 controlled by the printing control unit 120. First, the pickup roller 131 sends out the printing paper P in the paper stocker 180 from the paper stocker 180 one by one. The fed printing paper P travels to a contact position between the nip roller 132 and the conveyance belt 135. Then, while being sandwiched between the nip roller 132 and the transport belt 135, the transport belt 135 moves to the right in the drawing.

  When the printing paper P is conveyed to a position where the conveyance belt 135 faces the lower surface of the inkjet head 100, ink is ejected from the inkjet head 100 based on image data. Thus, the printer 1 forms an image on the printing paper P while conveying the printing paper P to the right on the conveyance belt 135. The printing paper P on which the image is formed is further conveyed rightward by the conveying belt 135 and is discharged to the paper receiver 190.

  FIG. 2 is a block diagram illustrating configurations of the print control unit 120 and the inkjet head 100. Each functional block of the print control unit 120 shown in FIG. 2 is realized mainly on a main control board (not shown) installed in the printer 1. The main control board includes a processor, a ROM (Read Only Memory), a RAM (Random Access Memory), various I / O (Input / Output) interfaces, various buses, and the like. Various programs for realizing the functional blocks shown in FIG. 2 are stored in the ROM on the main control board. A part of the functional blocks is realized by hardware such as a processor functioning based on the program. The other part of the functional block shown in FIG. 2 is realized by a circuit configuration dedicated to the functional block constructed on the main control board. Note that each functional block of the print control unit 120 shown in FIG. 2 may be realized on another control board installed in the inkjet head 100.

  The print control unit 120 includes a main control unit 121 (main control unit), a head drive unit 122, a memory 123 (storage unit), and a waveform data generation unit 124. When the main control unit 121 receives image data transmitted from a PC or the like, the main control unit 121 stores it in a print image data storage area constructed in the memory 123. Then, the pixel data included in the stored image data is sequentially extracted, and print data for ejecting ink is generated. Such print data for ink ejection is output to the head drive unit 122.

  In addition, a flushing condition table storage area is formed in the memory 123, and a flushing condition table in which the flushing condition and the temperature of the driver IC 101 are associated with each other is stored. The main control unit 121 generates print data for flushing based on the flushing condition table and temperature information from a temperature sensor 102 (to be described later) during a period when print data for ink ejection is not output. Further, the flushing print data is output to the head drive unit 122. On the other hand, the waveform data generation unit 124 stores waveform pattern data for ink ejection corresponding to the print density during gradation recording. The waveform data generating unit 124 also stores a plurality of flushing waveform pattern data corresponding to combinations of flushing conditions and temperature conditions. Then, the waveform data generation unit 124 outputs the waveform pattern data for flushing to the head driving unit 122 together with the waveform pattern data corresponding to each gradation for ink ejection.

  The printing cycle is the time required for the paper transport unit 130 to transport the print paper by a length of one pixel in the sub-scanning direction in FIG. Therefore, the printing cycle varies depending on the traveling speed of the conveyor belt 135 and the like. For example, the faster the conveyor belt 135 travels, the shorter the printing cycle. Therefore, in order to drive the printer 1 with a desired printing cycle, the output timing of the waveform pattern data from the waveform data generation unit 124, the conveyance speed of the printing paper by the paper conveyance unit 130, and the like are set on a predetermined position on the printing paper. Therefore, it is necessary to perform control in synchronism with the printing cycle so that desired dots are formed. Even when there is no explicit statement in the following description, it is assumed that the main control unit 121 performs control while synchronizing as described above.

  The head drive unit 122 distributes the print data output from the main control unit 121 for each driver IC (Integrated Circuit) 101 described later, and outputs the print data to the corresponding driver IC 101. Further, the head drive unit 122 generates a driver IC drive signal corresponding to the waveform pattern data output from the waveform data generation unit 124, and outputs this signal to each driver IC 101. As described above, the driver IC driving signal includes an ink ejection signal and a flushing signal.

  The print data from the head drive unit 122 includes information indicating a signal to be selected from the driver IC drive signal corresponding to each actuator 103. This print data is serial data. The driver IC 101 generates a parallel signal corresponding to each actuator 103 from the serial signal. Then, according to the instruction of the parallel signal, a predetermined driver IC driving signal is selected from the signal from the head driving unit 122, further amplified in power, and output to each actuator 103. As a result, a voltage pulse signal for ink ejection or flushing corresponding to what the print data indicates is supplied from the driver IC 101 to each actuator 103.

  When a voltage pulse signal is supplied from the driver IC 101, the actuator 103 operates based on the voltage pulse signal, and pressure is applied to the ink in each ink flow path 104. At this time, if the voltage pulse signal supplied to the actuator 103 has a waveform for ejecting ink (ejection signal), ink is ejected from the ink ejection port. On the other hand, when the voltage pulse signal has a flushing waveform (flushing signal), ink is not ejected from the ink ejection port, and the ink in the ink flow path is agitated.

  A temperature sensor 102 is installed inside the inkjet head 100. The temperature sensor 102 measures the temperature of the driver IC 101 and transmits a signal indicating the measured temperature to the main control unit 121.

  In the present embodiment, the temperature sensor 102 uses a part of the semiconductor constituting the driver IC 101 as a sensor. The energy gap or energy barrier of a semiconductor changes with temperature and decreases with increasing temperature. This temperature characteristic shows good linearity in a relatively wide range. For this reason, the driver IC 101 outputs a voltage corresponding to the energy gap or energy barrier from one of the output terminals, and the temperature of the driver IC 101 can be directly known from this voltage.

  FIG. 3 shows the waveform pattern indicated by the waveform pattern data output by the waveform data generation unit 124 and the print data output by the main control unit 121. As an example, FIG. 3A shows waveform patterns A1 and A2 for ink ejection and waveform patterns B and C for flushing. Each waveform pattern shown in FIG. 3A is a unit waveform pattern corresponding to one printing cycle. The waveform data generation unit 124 outputs data corresponding to the unit waveform pattern for each printing cycle. In addition, the horizontal axis of Fig.3 (a) has shown time.

  As shown in FIG. 3A, each waveform pattern includes a plurality of pulses. Each pulse shown in FIG. 3A corresponds to a driver IC driving signal generated by the head driving unit 122 according to these waveform patterns. The height of each pulse included in the waveform patterns A1 and A2 is adjusted to such a size that an amount of ink corresponding to a desired gradation is ejected by power amplification. Further, the widths of the pulses included in the waveform patterns B and C and the interval between the pulses are adjusted so as to prevent ink from being ejected from the ink ejection port even when power is amplified as described above. The number of pulses included in the waveform pattern B is greater than that included in the waveform pattern C.

  FIG. 3B to FIG. 3D are diagrams showing the concept of print data generated by the main control unit 121. FIG. 3B shows print data for ink ejection corresponding to image data, and FIGS. 3C and 3D show print data for flushing. In FIG. 3 (b) to FIG. 3 (d), rows c1, c2, c3,... Correspond to the actuators 103 included in the inkjet head 100, and columns r1, r2, r3,. Corresponds to the period. Each cell indicates a waveform pattern of a voltage pulse signal to be supplied to a certain actuator 103 in a certain printing cycle.

  For example, the cell (c1, r1) in FIG. 3B indicates that the waveform pattern to be supplied to the actuator 103 corresponding to c1 in the printing cycle corresponding to r1 is the waveform pattern A1. . Note that “x” indicates that no voltage pulse signal for ink ejection is supplied to the actuator 103 in the printing cycle, that is, ink should not be ejected.

  The main control unit 121 generates and outputs print data as shown in FIG. 3B based on the image data stored in the memory 123. At this time, the main control unit 121 outputs print data in a predetermined order. For example, (c1, r1), (c2, r1), (c3, r1),..., (C1, r2), (c2, r2), (c3, r2),. . The head driving unit 122 distributes the serial print data transmitted from the main control unit 121 in a predetermined order to each driver IC 101 according to the predetermined order. The driver IC 101 supplies a corresponding voltage pulse signal to each actuator 103 based on the distributed print data.

  Sg1 in FIG. 4 indicates a voltage pulse train signal to be supplied to the actuator 103 corresponding to the row c1 when the main control unit 121 outputs the print data in FIG. 3B. As shown in FIG. 3B, the data in the data row c1 are arranged in the order of the waveform pattern A1, the waveform pattern A2, the waveform pattern A1,. Therefore, as indicated by Sg1, the voltage pulse signals of FIG. 3A corresponding to these waveform patterns are sequentially supplied to the actuator 103 corresponding to c1 for each printing cycle.

  On the other hand, the main control unit 121 generates and outputs print data for flushing as shown in FIGS. 3 (c) and 3 (d). At this time, the main control unit 121 outputs the print data serially in the same manner as the print data for ink ejection. Whether the print data shown in FIG. 3 (c) or the print data shown in FIG. 3 (d) is output is selected based on temperature information from the temperature sensor 102, as will be described later. The When the flushing print data is output, the driver IC 101 supplies a voltage pulse signal corresponding to the print data to each actuator 103 as in the case of the ink discharge print data.

  Sg2 and Sg3 in FIG. 4 indicate voltage pulse train signals to be supplied to the actuators 103 when the main control unit 121 outputs the print data in FIGS. 3C and 3D, respectively. Yes. The print data for flushing is selected according to the temperature of the driver IC 101 as described above. Then, depending on whether the print data corresponding to FIG. 3 (c) or the print data corresponding to FIG. 3 (d) is output, two flushing voltage pulse train signals having different pulse frequencies are: This is selectively supplied to the actuator 103.

  Table 1 below shows a flushing condition table indicating flushing conditions according to temperature information from the temperature sensor 102. As described above, the flushing condition table is stored in the memory 123. The main control unit 121 generates print data according to the detection result (temperature of the driver IC 101) by the temperature sensor 102 immediately before the start of flushing. For example, if the temperature information from the temperature sensor 102 indicates that the temperature of the driver IC 101 is less than 40 ° C., print data corresponding to the waveform pattern B shown in the flushing condition table is generated. Output. As a result, the print data shown in FIG. 3C is output. In FIG. 4, the voltage pulse signal supplied to each actuator 103 is shown in time series as Sg2. On the other hand, if the temperature information from the temperature sensor 102 indicates that the temperature of the driver IC 101 is 40 ° C. or higher, print data corresponding to the waveform pattern C shown in the flushing condition table is generated. Output. As a result, the print data shown in FIG. 3D is output. In FIG. 4, the voltage pulse signal supplied to each actuator 103 is shown in time series as Sg3. That is, when the temperature of the driver IC 101 becomes equal to or higher than a predetermined threshold (40 ° C. in Table 1), the main control unit 121 generates a voltage pulse train signal having a lower pulse frequency than when the temperature is lower than the predetermined threshold. Corresponding flushing print data is generated and output (supply condition changing means).

  In addition, the flushing condition table includes a supply time condition for supplying a voltage pulse train signal for flushing. Regarding the temperature information from the temperature sensor 102, a long supply time is associated with a high temperature (40 degrees or more), and a short supply time is associated with a low temperature (less than 40 degrees). The main control unit 121 outputs print data for flushing over the supply period shown in Table 1. Here, the supply period in Table 1 corresponds to the number of repetitions of the printing cycle. The supply period is adjusted so that the total number of pulses supplied does not change depending on the temperature of the driver IC 101. For example, as shown in Table 1, when the temperature of the driver IC 101 is less than 40 ° C., the supply period is set to 1200. At this time, since the waveform pattern B includes five pulses for one printing cycle, the voltage pulse train signal supplied for flushing includes a total of 5 pulses × 1200 printing cycles = 6000 pulses. . On the other hand, when the temperature of the driver IC 101 is 40 ° C. or higher, the supply period is set to 2000. At this time, since the waveform pattern C includes three pulses for one printing cycle, the voltage pulse train signal supplied for flushing includes a total of 3 pulses × 2000 printing cycles = 6000 pulses. .

  In this embodiment, in this way, the supply period is set so that the voltage pulse train signal including the same number of pulses as a whole is supplied to the actuator 103 no matter what frequency of print data is supplied. Yes. As a result, when the temperature of the driver IC 101 is low, the flushing process is completed in a short time, and even when the temperature is high, an appropriate flushing process can be performed without resting the driver IC 101. Even if the same number of pulses are not always supplied, it is sufficient that the supply period is set so that a voltage pulse train signal exceeding the required number of pulses is supplied. For example, when print data is generated based on waveform patterns X and Y each having m and n (both are natural numbers) pulses for one printing cycle, m × (wave pattern X supply period) and n Each supply period should just be set so that x (the supply period of the waveform pattern Y) is not less than a predetermined value (6000 in Table 1).

  FIG. 5 illustrates processing performed by the main control unit 121 from when the printer 1 receives image data and data indicating the number of printed sheets from a PC or the like until the image corresponding to the image data is formed on the printing paper for the required number of sheets. It is a flowchart which shows a series of steps.

  First, the main controller 121 determines the flushing condition based on the temperature information from the temperature sensor 102 (S1). Specifically, referring to a flushing condition table stored in the memory 123, a waveform pattern serving as a basis for print data for flushing and a supply period for supplying a signal for flushing are determined.

  Next, the main controller 121 generates and outputs flushing print data based on the waveform pattern determined in S1 (S2). Then, the output of the print data is repeated by the print cycle corresponding to the supply period determined in S1 (S3, NO). During this time, the driver IC 101 outputs a voltage pulse for flushing to each actuator 103 at every printing cycle. When the print cycle corresponding to the supply period determined in S1 is repeated (S3, YES), the main control unit 121 generates and outputs print data for ink ejection corresponding to one print sheet. (S4). At this time, the print data is output divided into the number of repetitions of the print cycle necessary to complete the print. Then, the steps S1 to S4 are repeated for the required number of printing sheets (S5, NO). When printing of all the printing papers is completed (S5, YES), the main control unit 121 ends a series of steps.

  By realizing the configuration as described above in the present embodiment, when the temperature of the driver IC 101 is equal to or higher than a predetermined threshold, the driver IC 101 outputs a voltage pulse train signal for flushing with a lower pulse frequency to the actuator 103. Will be supplied.

  On the other hand, as the number of pulses included in the voltage pulse train signal increases, the amount of heat generated from the driver IC 101 generally increases. In particular, as shown in Sg2 and Sg3 of FIG. 4, a voltage pulse train signal for flushing with a large number of pulses causes the driver IC 101 to overheat. Furthermore, when an ink jet head fixed in the apparatus is used as in the present embodiment, a large number of ink discharges to the ink jet head as compared with a printer configured to move the head along the main scanning direction. An exit will be formed. In such a case, the number of actuators 103 increases, and the number of voltage pulse train signals that the driver IC 101 has to supply increases, so the amount of heat generated by the driver IC 101 also increases.

  However, according to the above configuration, when the temperature of the driver IC 101 reaches a certain level, switching to a voltage pulse train signal having a low frequency is performed, so that the temperature increase of the driver IC 101 is suppressed and the driver IC 101 is prevented from overheating.

  In addition, since the signal supply period is set so that the total number of pulses included in the voltage pulse train signal for flushing is the same, the number of pulses necessary for flushing is ensured even if the frequency of the pulse is changed. . That is, the effect of flushing is maintained even when the pulse frequency is changed to a low one.

  Further, the waveform data generation unit 124 outputs a plurality of waveform pattern data for flushing simultaneously with the waveform pattern data for ink ejection. For this reason, the main control unit 121 may generate the flushing print data in the same manner as the ink discharge print data. Therefore, the flushing signal is generated with a simple configuration.

<Modification>
The above is a description of a preferred embodiment of the present invention. However, the present invention is not limited to the above-described embodiment, and various modifications can be made as long as the contents are described in the means for solving the problem. It can be changed.

  For example, in the above-described embodiment, two types of flushing waveform pattern data having different numbers of pulses in one printing cycle are used. However, three or more types of waveform pattern data having different numbers of pulses in one printing cycle may be used. This makes it possible to adjust the flushing signal in more detail according to the temperature of the driver IC 101.

  In the above-described embodiment, the flushing print data generated by the main control unit 121 has continuous data indicating one waveform pattern as shown in FIGS. 3C and 3D. It is a thing. However, data indicating a plurality of waveform patterns may be mixed. For example, when the print data as shown in FIG. 6 is generated, the flushing data having an average frequency between the frequency corresponding to FIG. 3C and the frequency corresponding to FIG. Thus, a voltage pulse train signal is generated. When the main control unit 121 generates and outputs print data for flushing based on, for example, Table 2 below, the driver IC 101 outputs a voltage pulse train signal for flushing with a more appropriate frequency according to the temperature of the driver IC 101. 103. Therefore, more appropriate flushing control is performed so as to shorten the supply period as much as possible while suppressing overheating of the driver IC 101.

  Further, as a modification of this embodiment, the temperature measurement of the driver IC 101 is continued even during the flushing process, and if it exceeds a predetermined threshold temperature, the waveform pattern corresponding to a longer supply period is switched from that point. It may be. At this time, the total number of flushing at the completion of the flushing process (the total number of pulses applied to the actuator) may be a predetermined value or more.

  In the above-described embodiment, the main control unit 121 performs selection of an appropriate waveform pattern and determination of a supply period. However, the waveform data generation unit 124 may be configured to output any one of a plurality of flushing waveform pattern data based on the temperature information of the temperature sensor 102. According to this, the main control unit 121 does not need to select an appropriate waveform pattern to generate print data, and only needs to determine the supply period. Therefore, the main control unit 121 may always output the same print data during the flushing over the supply period indicated by the flushing condition table.

  In the above-described embodiment, the main control unit 121 determines the flushing condition based on the temperature information of the temperature sensor 102 every time flushing is performed. However, the main control unit 121 may have a configuration in which the temperature information of the temperature sensor 102 is monitored and the flushing condition is reset only when the temperature of the driver IC 101 exceeds a predetermined threshold.

1 is a schematic configuration diagram illustrating an inkjet printer according to an embodiment of the present invention. It is a block diagram which shows the structure of the printing control part of FIG. 1, and an inkjet head. It is a figure which shows the printing data and waveform pattern data which the main control part and waveform data generation part of FIG. 2 output. It is a figure which shows the voltage pulse train signal which driver IC supplies to an actuator according to the printing data and waveform pattern data of FIG. 3 is a flowchart illustrating a series of steps of processing executed by a main control unit in FIG. 2 when an image is formed on a plurality of printing sheets in the inkjet head printer in FIG. 1. It is a figure which shows the printing data different from FIG. 3 which a main control part outputs.

Explanation of symbols

1 Inkjet printer (printer)
100 Inkjet head 100a Head body 101 Driver IC
102 Temperature Sensor 104 Ink Flow Channel 120 Print Control Unit 121 Main Control Unit 123 Memory 124 Waveform Data Generation Unit 130 Paper Conveyance Unit 131 Roller 132 Pickup Roller 133 Followed Roller 134 Belt Roller 135 Conveyance Belt

Claims (5)

An ink channel having an ejection port for ejecting ink, and an ejection head having an actuator for applying pressure to the ink filled in the ink channel;
A driver chip that supplies a discharge signal, which is a signal for discharging ink from the discharge port, to the actuator, and supplies a flushing signal including a pulse train that does not discharge ink from the discharge port to the actuator;
Temperature measuring means for measuring the temperature of the driver chip; and
Supply condition changing means for changing the frequency of a pulse included in the flushing signal supplied by the driver chip to a smaller one when the temperature of the driver chip measured by the temperature measuring means is equal to or higher than a predetermined threshold; An ink jet recording apparatus comprising: The supply condition changing means is
The supply period is changed together with the frequency of the pulse so that a product of the frequency of the pulse and the length of the supply period of the flushing signal becomes a predetermined value or more after the change of the frequency of the pulse. Item 10. The ink jet recording apparatus according to Item 1. A transport unit for transporting a recording medium to a position facing the ejection port;
Print control means for supplying the ejection signal to the actuator chip to the actuator so as to form an image on the recording medium conveyed by the conveyance unit;
And a main control means for controlling the transport unit and the print control means so that the supply period after the change by the supply condition changing means and the period during which an image is formed on the recording medium do not overlap. The ink jet recording apparatus according to claim 1, wherein: Waveform generation means for supplying a plurality of flushing signals having different waveforms to the driver chip;
The supply condition changing means outputs a signal indicating which of the plurality of flushing signals transmitted from the waveform generating means is supplied to the actuator so that the temperature of the driver chip is less than the threshold value. To the driver chip,
The driver chip selects the flushing signal indicated by the signal from the supply condition changing unit from the plurality of flushing signals generated by the waveform generation unit and supplies the selected flushing signal to the actuator. The ink jet recording apparatus according to claim 1, wherein the ink jet recording apparatus is an ink jet recording apparatus. Two pieces of flushing information respectively indicating any two of the plurality of flushing signals generated by the waveform generation unit are stored in association with each of a temperature region below the predetermined threshold and a temperature region above the predetermined threshold. A storage means,
The supply condition changing unit stores the storage unit in association with the temperature region including the temperature of the driver chip measured by the temperature measuring unit among the plurality of flushing signals generated by the waveform generating unit. 5. The ink jet recording apparatus according to claim 4, wherein a signal instructing to supply the flushing signal indicated by the flushing information is supplied to the driver chip.

Images